The document discusses a study analyzing the properties of cake layers formed during ultrafiltration of polydisperse silica colloid dispersions. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze fouled membranes and directly compare the particle arrangement and average thickness of cake layers formed under different conditions. Results from SEM and AFM analysis corresponded in terms of particle arrangement and average cake thickness. A resistance model was used to estimate specific cake resistance from filtration rate and cake layer thickness analysis via SEM.
This paper addresses the fracture toughness ( ), or also known as critical stress intensity Factor, according to
conditions of Lineal Elastic Fracture Mechanics (LEFM). The characterization of the mechanical properties in
tensile and fracture toughness of structural steel pipes API-5L used in hydrocarbons transportation was
performed. For fracture toughness, the material was tested through fatigue crack propagation on standardized
compact specimen (CT) according to ASTM E-399 norm. A thickness (B) equal to and a crack size (a) equal
to 0.5w were used. With the porpoise of establishing the adequate conditions at the crack tip, the specimens were
subjected to fatigue pre-cracking by application of repeated cycles of load in tensile-tensile and constant load
amplitude with a load ratio of R = 0.1. The experimental Compliance method was used based on data obtained
from load vs. Crack Mouth Opening Displacement (CMOD). The results show a Stress Intensity factor of 35.88
MPa√m for a 25 mm crack size specimen. The device used for testing is a MTS-810 machine with capacity of
100KN and 6 kHz sampling rate, which meets the conditions of the ASTM E-399 standard. The cracking
susceptibility of steel is influenced by the size, morphology and distribution of non-metallic inclusions,
thermochemical interaction with the environment and microstructure.
1) The document analyzes the effect of brine solution concentration on the grain size formations in AISI 1080 low carbon steel samples through heat treatment and quenching.
2) Fractal analysis was used to characterize the grain sizes, with the sphericity and fractal dimension values providing information on the grain shape and complexity.
3) The results showed that quenching in a 5.5 mol/dm3 brine solution produced grain sizes with the closest to perfect spherical shapes and most regular distribution, as indicated by sphericity and fractal dimension values of 0.8386 and 1.0947 respectively.
Abstract The present research work is to determine buckling load per unit length in rectangular plate with circular cut-outs under bi-axial compression using 2D finite element analysis. The commercial finite element analysis software ANSYS has been successfully executed. The buckling factors are evaluated by changing the position of the holes, length to thickness ratio. The effect of changing the position of holes, a/b ratio, b/t ratio and buckling load per unit length is discussed. The results shows that buckling load per unit length is in clamped-clamped boundary conditions and buckling load is more at top positioned hole, decreases with increase in aspect ratio, decrease with increase breadth to thickness ratio. Keywords: Buckling analysis, Finite element method, Buckling load per unit length , carbon/epoxy composite plate, aspect ratio, b/t ratio, and Biaxial load.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
The document summarizes an investigation comparing experimental and computational modeling results of grain deformation in a cast nickel superalloy. Digital image correlation was used to experimentally measure strain distributions across a tensile sample, finding heterogeneous strain localized in certain grains. A crystal plasticity finite element model was developed to simulate the deformation using orientations from EBSD maps. The model showed improved agreement with experimental strain distributions at lower values of the strain rate sensitivity parameter m, but still some disagreement on strain localization. Including subsurface grains in the model further improved agreement, showing the importance of full 3D microstructure representation.
Prediction Models for Sliding Wear of AA3003/Al2O3 CompositesIJERA Editor
In the present work, the AA3003/Al2O3 metal matrix composites were manufactured at 10% and 30% volume
fractions of Al2O3. The composites were wear tested at different levels of normal load, sliding speed and sliding
distances. The microstructure of worn surfaces pertaining to AA3003/ Al2O3 composite reveals the fracture of
AA3033 alloy matrix as well as the detachment of Al2O3 particles from the matrix.
Framework for assessment of shear strength parameters ofIAEME Publication
This document discusses a framework for assessing the shear strength parameters of residual tropical soils. It begins by providing background on shear strength and how it is typically measured through laboratory tests like direct shear tests and triaxial tests. However, these tests have limitations in simulating field conditions. The objective of the paper is then presented - to develop a phenomenological model to predict shear strength parameters from index properties that are easier to measure, like liquid limit and maximum dry density. This could provide a way to rapidly estimate shear strength when traditional testing methods are not available or feasible. The paper reviews previous studies on correlating index properties with shear strength and predicting unsaturated soil strength. It then discusses soil state and volumetric strain, and defines bulk modulus as
Prof G.K.Pradhan successfully demonstrted the use of empty plastic bottles in explosives column during blasting. Resulted is savings in blasting cost and immense benefits attached environmental problems.
This paper addresses the fracture toughness ( ), or also known as critical stress intensity Factor, according to
conditions of Lineal Elastic Fracture Mechanics (LEFM). The characterization of the mechanical properties in
tensile and fracture toughness of structural steel pipes API-5L used in hydrocarbons transportation was
performed. For fracture toughness, the material was tested through fatigue crack propagation on standardized
compact specimen (CT) according to ASTM E-399 norm. A thickness (B) equal to and a crack size (a) equal
to 0.5w were used. With the porpoise of establishing the adequate conditions at the crack tip, the specimens were
subjected to fatigue pre-cracking by application of repeated cycles of load in tensile-tensile and constant load
amplitude with a load ratio of R = 0.1. The experimental Compliance method was used based on data obtained
from load vs. Crack Mouth Opening Displacement (CMOD). The results show a Stress Intensity factor of 35.88
MPa√m for a 25 mm crack size specimen. The device used for testing is a MTS-810 machine with capacity of
100KN and 6 kHz sampling rate, which meets the conditions of the ASTM E-399 standard. The cracking
susceptibility of steel is influenced by the size, morphology and distribution of non-metallic inclusions,
thermochemical interaction with the environment and microstructure.
1) The document analyzes the effect of brine solution concentration on the grain size formations in AISI 1080 low carbon steel samples through heat treatment and quenching.
2) Fractal analysis was used to characterize the grain sizes, with the sphericity and fractal dimension values providing information on the grain shape and complexity.
3) The results showed that quenching in a 5.5 mol/dm3 brine solution produced grain sizes with the closest to perfect spherical shapes and most regular distribution, as indicated by sphericity and fractal dimension values of 0.8386 and 1.0947 respectively.
Abstract The present research work is to determine buckling load per unit length in rectangular plate with circular cut-outs under bi-axial compression using 2D finite element analysis. The commercial finite element analysis software ANSYS has been successfully executed. The buckling factors are evaluated by changing the position of the holes, length to thickness ratio. The effect of changing the position of holes, a/b ratio, b/t ratio and buckling load per unit length is discussed. The results shows that buckling load per unit length is in clamped-clamped boundary conditions and buckling load is more at top positioned hole, decreases with increase in aspect ratio, decrease with increase breadth to thickness ratio. Keywords: Buckling analysis, Finite element method, Buckling load per unit length , carbon/epoxy composite plate, aspect ratio, b/t ratio, and Biaxial load.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
The document summarizes an investigation comparing experimental and computational modeling results of grain deformation in a cast nickel superalloy. Digital image correlation was used to experimentally measure strain distributions across a tensile sample, finding heterogeneous strain localized in certain grains. A crystal plasticity finite element model was developed to simulate the deformation using orientations from EBSD maps. The model showed improved agreement with experimental strain distributions at lower values of the strain rate sensitivity parameter m, but still some disagreement on strain localization. Including subsurface grains in the model further improved agreement, showing the importance of full 3D microstructure representation.
Prediction Models for Sliding Wear of AA3003/Al2O3 CompositesIJERA Editor
In the present work, the AA3003/Al2O3 metal matrix composites were manufactured at 10% and 30% volume
fractions of Al2O3. The composites were wear tested at different levels of normal load, sliding speed and sliding
distances. The microstructure of worn surfaces pertaining to AA3003/ Al2O3 composite reveals the fracture of
AA3033 alloy matrix as well as the detachment of Al2O3 particles from the matrix.
Framework for assessment of shear strength parameters ofIAEME Publication
This document discusses a framework for assessing the shear strength parameters of residual tropical soils. It begins by providing background on shear strength and how it is typically measured through laboratory tests like direct shear tests and triaxial tests. However, these tests have limitations in simulating field conditions. The objective of the paper is then presented - to develop a phenomenological model to predict shear strength parameters from index properties that are easier to measure, like liquid limit and maximum dry density. This could provide a way to rapidly estimate shear strength when traditional testing methods are not available or feasible. The paper reviews previous studies on correlating index properties with shear strength and predicting unsaturated soil strength. It then discusses soil state and volumetric strain, and defines bulk modulus as
Prof G.K.Pradhan successfully demonstrted the use of empty plastic bottles in explosives column during blasting. Resulted is savings in blasting cost and immense benefits attached environmental problems.
Evaluation of fracture toughness of sintered silica nickel nanocompositeseSAT Journals
The document evaluates the fracture toughness of silica-nickel nanocomposites using micro-Vickers indentation technique. It finds that fracture toughness increases with increasing nickel content. The Vickers indentation results in two types of cracks - Palmqvist cracks at low loads and median cracks at high loads. Equations are used to calculate fracture toughness values from the crack lengths and loads. The values range from 1.76 to 3.64 MPa√m and increase with nickel content and load, indicating that nickel improves fracture toughness of the silica composites.
Graphene is a material that attracts attention in technical textile applications as in many other areas due to its outstanding features. In this study, it was aimed to investigate the performance properties of graphene coated fabrics. Pre-treated polyester fabrics were coated with nano-graphene powders at different concentration rates (50, 100 and 200 g/kg) by knife-over-roll technique. According to test results, generally, the graphene coating had a positive effect on the performance properties of polyester fabrics.
This document summarizes research on developing a multi-scale modeling approach to predict the structural behavior of carbon fiber reinforced composite pipes used for offshore oil and gas risers. The approach models the pipe behavior at the micro, meso, and macro scales and links the scales together. Experiments were conducted to validate the modeling approach and determine material properties at each scale. Results showed good agreement between predicted and experimental properties and structural response at different loading conditions. The multi-scale modeling approach shows promise for designing composite risers while addressing current limitations in experience, standards, and design methodologies.
This document discusses applying the NCHRP-1-28 resilient modulus model to characterize blended unbound granular materials in Sudan. An experimental testing program measured the resilient modulus of blended samples using dynamic triaxial tests. The NCHRP-1-28 model was used to predict resilient modulus values, which showed good agreement with measured values, being 8-10% lower, providing conservative estimates. The materials tested included natural gravels blended with sand and crushed stone to meet gradation specifications for base materials. Measured properties like density, CBR and gradation are reported for the blended samples.
Numerical study of behavior of square footing on geogrid reinforced flyash be...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Statistical evaluation of compression index equationsIAEME Publication
This document discusses statistical evaluation of equations for predicting the compression index (Cc) of soils. Twelve commonly used equations that predict Cc based on parameters like liquid limit, plasticity index, dry density, and void ratio are considered. Statistical analysis is performed to evaluate the effectiveness of the equations. One-way and two-way analysis of variance (ANOVA) tests are conducted using a database of 178 soil samples to compare predicted and observed Cc values. The tests indicate that soil classification and prediction method have a significant influence on the deviation between predicted and observed Cc. Certain models are found to be applicable only to some soil classification groups. The best models for different soil groups and for all soil types are identified using statistical tests.
APPRAISAL ON THE STRENGTH OF CONCRETE PRODUCED WITH VARYING AGGREGATE SIZEIAEME Publication
Compressive strength is one of the important properties of concrete as it influences the durability requirements of concrete. This work presents the effects of varying size of aggregate on the strength of concrete. The coarse aggregates used for this study were 10mm, 12.5mm and 19mm uncrushed gravel with river sand as fine aggregate. Sieve analysis was carried out on the aggregates. A nominal mix of 1:2:4 was adopted for the mix and the mix proportions were calculated by weight. The concrete test cubes used were made in batches with each batch containing just one coarse aggregate size. Two test cubes each were made respectively for each batch making a total of 18 cubes and cur ed for 7, 21, and 28 days respectively.
This study used finite element modeling to analyze swelling behavior in a tunnel excavated through marl rock. Laboratory tests on marl rock samples were used to calibrate two finite element programs, FISS and Nisa-II. FISS modeled the tunnel using the laboratory swelling test results. Nisa-II modeled time-dependent creep behavior by defining a creep function relating stress, strain, and time. Both programs analyzed stresses around the tunnel and indicated higher stresses in the sidewalls compared to the roof and floor. The study demonstrated a method to numerically model swelling behavior in tunnels using laboratory test data.
Experimental and numerical evaluation of plasticity model with ductile damage...IJERA Editor
This work aims to develop a methodology for numerical evaluation via finite elements applied to projects shields sheet metal. To validate the methodology physical test were conduct and were compare with the numerical simulation. In the simulation, a plasticity material modelit was used at high strain rates, besides the insertion of a damage model through forming limit diagram (FLD) to capture the initiation of damage and energy criteria for propagation of the fracture. The tested shielding design is for the II-A protection level using the type 9mm ammunition.
Mathematical Relationships between the Compressive Strength and Some Other St...IOSR Journals
This document establishes mathematical relationships between the compressive strength and other properties (water absorption, flexural strength, and split tensile strength) of sand-quarry dust blocks through regression analysis. Tests were conducted on blocks with varying mix ratios of cement, sand, and quarry dust. Linear and quadratic models relating each additional property to compressive strength were developed. The models were found to have low standard error and high coefficient of determination, indicating they adequately predict relationships between compressive strength and other block properties. The relationships can be used when only compressive strength testing is conducted to estimate additional properties.
Taguchi Analysis of Erosion Wear Maize Husk Based Polymer CompositeIJMER
Amids the growing concern on environmental issues, science is seeking various alternatives to replace the synthetic and non degradable fibers composites with environment friendly biocomposites of comparable characteristics and performance. Visualizing the importance of polymer composites and owing to issue of ecological concerns, this experiment is an attempt to further investigate possibility of bio composites (Particularly maize husk) as an alternative of available synthetic polymer composites. Taking one leap forward the experiment also approximate qualities the effect of individual parameters on erosion by the application of Taguchi Technique. Experimental system were devised and designed to study the erosion rate of maize husk fiber Reinforced Polymer composites at various impingement angles, with profound variables such as particle velocity, fiber content, and particle size (erodent size) To cast the composite epoxy Resin LY 556 with corresponding hardener HY 551 was used. The erodent size was in range of it irregular shape. The tribological performance of sheets was investigated in respect to set of various variable parameters as suggested by L16 series of Taguchi Techniques. The morphological feature before and after the experiments were studies using SEM.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Size effect of plain concrete beams–an experimental studyeSAT Journals
Abstract
The paper analyses the size dependency of the fracture energy (GF) and the effective length of fracture process zone (Cf) of concrete
determined as per the Bazant’s Size effect method and RILEM Work-of-fracture methods. The fracture parameters (GF,Cf) are
determined by measuring the maximum loads of geometrically similar notched plain concrete (M25) specimens of different sizes in a
size ratio of 1:5 with different pre-cast notch depths (a/d=0.15, 0.30 and 0.45) under three point bending through load-deflection
curves. In each notch depth ratio, 15 beams are cast and tested with 03 similar specimens in each size of the beams. Total beams
tested are 45.The variation of both the fracture energy and the effective length of fracture process zone as a function of the specimen
size and notch depth is determined using Bazant’s Size effect method and RILEM Work-of-fracture method. Fracture energy and
Fracture process zone length determined by Size effect method are found to be decreasing with the increasing notch depth ratios.
Fracture energy calculated using Work-of-fracture method is increasing with the increase in size of specimen and decreasing with the
increasing notch depth ratios.
Improvement of bearing capacity of square footing on compacted pond ash with ...eSAT Journals
Abstract Pond ash is waste by product which is producing in huge quantity by thermal power plants. The disposal of pond ash is the major problem to the environment. The way for disposing pond ash would be as a structural fill for low lying areas and used as embankment material. In this paper laboratory investigations are carried out to improve the bearing capacity of pond ash reinforced with geo-grid by conducting load tests in a model tank. The parameters varied during the tests were number of reinforcement layers and overlapping of reinforcement. The improvement of ultimate bearing capacity is observed. The ultimate bearing capacity ratios were evaluated. Keywords: Pond ash, Geogrid, Square footing, u/B, h/B, b/B, Bearing capacity ratio
This document discusses several methods for estimating the fatigue life of Type 304LN stainless steel under strain-controlled cyclic loading, including the four-point correlation method, modified four-point correlation method, universal slopes method, modified universal slopes method, uniform material law, hardness method, median's method, and methods proposed by Mitchell and Basan. The results of estimating fatigue life using these methods are compared to experimental strain-controlled fatigue test results on Type 304LN stainless steel at various strain amplitudes. Most methods overestimate fatigue life except the median's method, which provides a reasonably accurate estimation of fatigue life, especially at higher strain amplitudes. Basan's method, modified universal slopes method, and uniform material law also predict fatigue life with reasonable accuracy
Modified maximum tangential stress criterion for fracture behavior of zirconi...dentalid
The veneering porcelain sintered on zirconia is widely used in dental prostheses, but
repeated mechanical loadings may cause a fracture such as edge chipping or delamination.
In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bilayered
components subjected to mixed mode loadings, the accuracy of a new and
traditional fracture criteria are investigated. A modified maximum tangential stress
criterion considering the effect of T-stress and critical distance theory is introduced, and
compared to three traditional fracture criteria. Comparisons to the recently published
fracture test data show that the traditional fracture criteria are not able to properly predict
the fracture initiation conditions in zirconia/veneer bi-material joints. The modified
maximum tangential stress criterion provides more accurate predictions of the experimental
results than the traditional fracture criteria
This document presents a study that evaluated the correlation between soaked California Bearing Ratio (CBRSoaked) and Undrained Shear Strength (Su) for artificially prepared soils with varying Plasticity Index. Soil samples were prepared with varying percentages of red powder, clay powder, and sand powder to change the Plasticity Index. Testing included Atterberg limits, compaction, CBR testing, and direct shear testing. The results showed a polynomial correlation between CBRSoaked and Su. The correlation was validated with a variation of less than 1.5% for test samples. The study concluded a non-linear correlation was obtained between CBRSoaked and Su for soils with varying Plasticity Index.
William Gaffney analyzed the deformation of P91 martensitic steel at high temperatures using finite element modeling of a three-point bend specimen. 3D finite element models of the specimen were created with and without pins to model the experimental setup. The model with pins and nonlinear geometry showed the best correlation with experimental load-displacement data. Analysis of plastic strain in the models found more localized strain at the notch tip with nonlinear geometry. The study aims to further understand deformation behavior of P91 steel used in power generation components.
This document summarizes research on the microstructure and damage initiation in a duplex stainless steel. Electron backscatter diffraction was used to correlate the local phase morphology with crystallographic properties. In situ tensile tests were performed to characterize strain fields and observe sites of damage nucleation. Damage was found to nucleate near stress concentrations rather than in highly deformed areas. Finite element modeling accounted for the bicrystal morphology and anisotropic plasticity of phases. Damage initiation was correlated with local crystallographic orientations and common slip systems between phases.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document discusses the assessment of seismic susceptibility of reinforced concrete (RC) buildings. It begins with an introduction to earthquakes and the importance of vulnerability assessment in mitigating earthquake risks and losses. It then describes modeling the nonlinear behavior of RC building elements and performing pushover analysis to evaluate building performance. The document outlines modeling RC frames and developing moment-curvature relationships. It also summarizes the results of pushover analyses on sample 2D and 3D RC frames with and without shear walls. The conclusions emphasize that pushover analysis effectively assesses building properties but has limitations, and that capacity spectrum method provides appropriate results for evaluating building response and retrofitting impact.
Evaluation of fracture toughness of sintered silica nickel nanocompositeseSAT Journals
The document evaluates the fracture toughness of silica-nickel nanocomposites using micro-Vickers indentation technique. It finds that fracture toughness increases with increasing nickel content. The Vickers indentation results in two types of cracks - Palmqvist cracks at low loads and median cracks at high loads. Equations are used to calculate fracture toughness values from the crack lengths and loads. The values range from 1.76 to 3.64 MPa√m and increase with nickel content and load, indicating that nickel improves fracture toughness of the silica composites.
Graphene is a material that attracts attention in technical textile applications as in many other areas due to its outstanding features. In this study, it was aimed to investigate the performance properties of graphene coated fabrics. Pre-treated polyester fabrics were coated with nano-graphene powders at different concentration rates (50, 100 and 200 g/kg) by knife-over-roll technique. According to test results, generally, the graphene coating had a positive effect on the performance properties of polyester fabrics.
This document summarizes research on developing a multi-scale modeling approach to predict the structural behavior of carbon fiber reinforced composite pipes used for offshore oil and gas risers. The approach models the pipe behavior at the micro, meso, and macro scales and links the scales together. Experiments were conducted to validate the modeling approach and determine material properties at each scale. Results showed good agreement between predicted and experimental properties and structural response at different loading conditions. The multi-scale modeling approach shows promise for designing composite risers while addressing current limitations in experience, standards, and design methodologies.
This document discusses applying the NCHRP-1-28 resilient modulus model to characterize blended unbound granular materials in Sudan. An experimental testing program measured the resilient modulus of blended samples using dynamic triaxial tests. The NCHRP-1-28 model was used to predict resilient modulus values, which showed good agreement with measured values, being 8-10% lower, providing conservative estimates. The materials tested included natural gravels blended with sand and crushed stone to meet gradation specifications for base materials. Measured properties like density, CBR and gradation are reported for the blended samples.
Numerical study of behavior of square footing on geogrid reinforced flyash be...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Statistical evaluation of compression index equationsIAEME Publication
This document discusses statistical evaluation of equations for predicting the compression index (Cc) of soils. Twelve commonly used equations that predict Cc based on parameters like liquid limit, plasticity index, dry density, and void ratio are considered. Statistical analysis is performed to evaluate the effectiveness of the equations. One-way and two-way analysis of variance (ANOVA) tests are conducted using a database of 178 soil samples to compare predicted and observed Cc values. The tests indicate that soil classification and prediction method have a significant influence on the deviation between predicted and observed Cc. Certain models are found to be applicable only to some soil classification groups. The best models for different soil groups and for all soil types are identified using statistical tests.
APPRAISAL ON THE STRENGTH OF CONCRETE PRODUCED WITH VARYING AGGREGATE SIZEIAEME Publication
Compressive strength is one of the important properties of concrete as it influences the durability requirements of concrete. This work presents the effects of varying size of aggregate on the strength of concrete. The coarse aggregates used for this study were 10mm, 12.5mm and 19mm uncrushed gravel with river sand as fine aggregate. Sieve analysis was carried out on the aggregates. A nominal mix of 1:2:4 was adopted for the mix and the mix proportions were calculated by weight. The concrete test cubes used were made in batches with each batch containing just one coarse aggregate size. Two test cubes each were made respectively for each batch making a total of 18 cubes and cur ed for 7, 21, and 28 days respectively.
This study used finite element modeling to analyze swelling behavior in a tunnel excavated through marl rock. Laboratory tests on marl rock samples were used to calibrate two finite element programs, FISS and Nisa-II. FISS modeled the tunnel using the laboratory swelling test results. Nisa-II modeled time-dependent creep behavior by defining a creep function relating stress, strain, and time. Both programs analyzed stresses around the tunnel and indicated higher stresses in the sidewalls compared to the roof and floor. The study demonstrated a method to numerically model swelling behavior in tunnels using laboratory test data.
Experimental and numerical evaluation of plasticity model with ductile damage...IJERA Editor
This work aims to develop a methodology for numerical evaluation via finite elements applied to projects shields sheet metal. To validate the methodology physical test were conduct and were compare with the numerical simulation. In the simulation, a plasticity material modelit was used at high strain rates, besides the insertion of a damage model through forming limit diagram (FLD) to capture the initiation of damage and energy criteria for propagation of the fracture. The tested shielding design is for the II-A protection level using the type 9mm ammunition.
Mathematical Relationships between the Compressive Strength and Some Other St...IOSR Journals
This document establishes mathematical relationships between the compressive strength and other properties (water absorption, flexural strength, and split tensile strength) of sand-quarry dust blocks through regression analysis. Tests were conducted on blocks with varying mix ratios of cement, sand, and quarry dust. Linear and quadratic models relating each additional property to compressive strength were developed. The models were found to have low standard error and high coefficient of determination, indicating they adequately predict relationships between compressive strength and other block properties. The relationships can be used when only compressive strength testing is conducted to estimate additional properties.
Taguchi Analysis of Erosion Wear Maize Husk Based Polymer CompositeIJMER
Amids the growing concern on environmental issues, science is seeking various alternatives to replace the synthetic and non degradable fibers composites with environment friendly biocomposites of comparable characteristics and performance. Visualizing the importance of polymer composites and owing to issue of ecological concerns, this experiment is an attempt to further investigate possibility of bio composites (Particularly maize husk) as an alternative of available synthetic polymer composites. Taking one leap forward the experiment also approximate qualities the effect of individual parameters on erosion by the application of Taguchi Technique. Experimental system were devised and designed to study the erosion rate of maize husk fiber Reinforced Polymer composites at various impingement angles, with profound variables such as particle velocity, fiber content, and particle size (erodent size) To cast the composite epoxy Resin LY 556 with corresponding hardener HY 551 was used. The erodent size was in range of it irregular shape. The tribological performance of sheets was investigated in respect to set of various variable parameters as suggested by L16 series of Taguchi Techniques. The morphological feature before and after the experiments were studies using SEM.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Size effect of plain concrete beams–an experimental studyeSAT Journals
Abstract
The paper analyses the size dependency of the fracture energy (GF) and the effective length of fracture process zone (Cf) of concrete
determined as per the Bazant’s Size effect method and RILEM Work-of-fracture methods. The fracture parameters (GF,Cf) are
determined by measuring the maximum loads of geometrically similar notched plain concrete (M25) specimens of different sizes in a
size ratio of 1:5 with different pre-cast notch depths (a/d=0.15, 0.30 and 0.45) under three point bending through load-deflection
curves. In each notch depth ratio, 15 beams are cast and tested with 03 similar specimens in each size of the beams. Total beams
tested are 45.The variation of both the fracture energy and the effective length of fracture process zone as a function of the specimen
size and notch depth is determined using Bazant’s Size effect method and RILEM Work-of-fracture method. Fracture energy and
Fracture process zone length determined by Size effect method are found to be decreasing with the increasing notch depth ratios.
Fracture energy calculated using Work-of-fracture method is increasing with the increase in size of specimen and decreasing with the
increasing notch depth ratios.
Improvement of bearing capacity of square footing on compacted pond ash with ...eSAT Journals
Abstract Pond ash is waste by product which is producing in huge quantity by thermal power plants. The disposal of pond ash is the major problem to the environment. The way for disposing pond ash would be as a structural fill for low lying areas and used as embankment material. In this paper laboratory investigations are carried out to improve the bearing capacity of pond ash reinforced with geo-grid by conducting load tests in a model tank. The parameters varied during the tests were number of reinforcement layers and overlapping of reinforcement. The improvement of ultimate bearing capacity is observed. The ultimate bearing capacity ratios were evaluated. Keywords: Pond ash, Geogrid, Square footing, u/B, h/B, b/B, Bearing capacity ratio
This document discusses several methods for estimating the fatigue life of Type 304LN stainless steel under strain-controlled cyclic loading, including the four-point correlation method, modified four-point correlation method, universal slopes method, modified universal slopes method, uniform material law, hardness method, median's method, and methods proposed by Mitchell and Basan. The results of estimating fatigue life using these methods are compared to experimental strain-controlled fatigue test results on Type 304LN stainless steel at various strain amplitudes. Most methods overestimate fatigue life except the median's method, which provides a reasonably accurate estimation of fatigue life, especially at higher strain amplitudes. Basan's method, modified universal slopes method, and uniform material law also predict fatigue life with reasonable accuracy
Modified maximum tangential stress criterion for fracture behavior of zirconi...dentalid
The veneering porcelain sintered on zirconia is widely used in dental prostheses, but
repeated mechanical loadings may cause a fracture such as edge chipping or delamination.
In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bilayered
components subjected to mixed mode loadings, the accuracy of a new and
traditional fracture criteria are investigated. A modified maximum tangential stress
criterion considering the effect of T-stress and critical distance theory is introduced, and
compared to three traditional fracture criteria. Comparisons to the recently published
fracture test data show that the traditional fracture criteria are not able to properly predict
the fracture initiation conditions in zirconia/veneer bi-material joints. The modified
maximum tangential stress criterion provides more accurate predictions of the experimental
results than the traditional fracture criteria
This document presents a study that evaluated the correlation between soaked California Bearing Ratio (CBRSoaked) and Undrained Shear Strength (Su) for artificially prepared soils with varying Plasticity Index. Soil samples were prepared with varying percentages of red powder, clay powder, and sand powder to change the Plasticity Index. Testing included Atterberg limits, compaction, CBR testing, and direct shear testing. The results showed a polynomial correlation between CBRSoaked and Su. The correlation was validated with a variation of less than 1.5% for test samples. The study concluded a non-linear correlation was obtained between CBRSoaked and Su for soils with varying Plasticity Index.
William Gaffney analyzed the deformation of P91 martensitic steel at high temperatures using finite element modeling of a three-point bend specimen. 3D finite element models of the specimen were created with and without pins to model the experimental setup. The model with pins and nonlinear geometry showed the best correlation with experimental load-displacement data. Analysis of plastic strain in the models found more localized strain at the notch tip with nonlinear geometry. The study aims to further understand deformation behavior of P91 steel used in power generation components.
This document summarizes research on the microstructure and damage initiation in a duplex stainless steel. Electron backscatter diffraction was used to correlate the local phase morphology with crystallographic properties. In situ tensile tests were performed to characterize strain fields and observe sites of damage nucleation. Damage was found to nucleate near stress concentrations rather than in highly deformed areas. Finite element modeling accounted for the bicrystal morphology and anisotropic plasticity of phases. Damage initiation was correlated with local crystallographic orientations and common slip systems between phases.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document discusses the assessment of seismic susceptibility of reinforced concrete (RC) buildings. It begins with an introduction to earthquakes and the importance of vulnerability assessment in mitigating earthquake risks and losses. It then describes modeling the nonlinear behavior of RC building elements and performing pushover analysis to evaluate building performance. The document outlines modeling RC frames and developing moment-curvature relationships. It also summarizes the results of pushover analyses on sample 2D and 3D RC frames with and without shear walls. The conclusions emphasize that pushover analysis effectively assesses building properties but has limitations, and that capacity spectrum method provides appropriate results for evaluating building response and retrofitting impact.
Experimental investigation of thermal performance of petrol engine using fuel...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Implementation of lru algorithm for location update in wireless m2 m communic...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Study of mechanical and morphological properties of glass fiber reinforced mo...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
20160219 - F. Grati - Toma - Maternal MalignanciesRoberto Scarafia
Origin of cfDNA testing (Synonyms – NIPT or NIPS) for fetal aneuploidies
Performances of cfDNA testing for fetal aneuploidies
Maternal malignancies as a possible source for false positive cfDNA results
How to detect when the cause of FP result is a maternal malignancy
Implications for genetic counseling
Modeling the wettability alteration tendencies of bioproducts during microbia...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Detection of crossover & bifurcation points on a retinal fundus image by anal...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Analysis of factors for enhancing energy conservation in indian railway works...eSAT Publishing House
This document summarizes a study analyzing factors that influence energy conservation in Indian railway workshops. It discusses energy usage at the Carriage Repair Workshop in Hubli and Central Workshops in Mysore. 25 variables that could potentially impact energy conservation efforts were identified through interviews. A questionnaire was administered to 71 respondents at Hubli and 57 at Mysore to understand preferences on these variables. Principal component analysis identified 8 key factors: motivation for employees, knowledge and attitude, preventive measures, timely decision making, motivation for energy conservation, management role, procurement process, and human factors. The study aims to provide insights for improving energy conservation policies and strategies in Indian railway workshops.
Weight optimization of fix jaw of rear vice of horizontal band saw machine us...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Applying edge density based region growing with frame difference for detectin...eSAT Publishing House
1. The document presents a method for detecting moving objects in video surveillance systems using edge density based region growing with frame difference.
2. It involves preprocessing frames through edge detection, frame differencing to eliminate stationary backgrounds, and applying edge density based region growing to connect regions of moving objects.
3. Experimental results on videos of a moving person and cylinder show the method can accurately detect moving objects in complex backgrounds.
Low complexity digit serial fir filter by multiple constant multiplication al...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Increasing network efficiency by preventing attacks at access layereSAT Publishing House
This document discusses increasing network efficiency by preventing attacks at the access layer. It describes common attacks like MAC address flooding, DHCP starvation, and DHCP spoofing that switches are vulnerable to. It then provides configurations for switch port security, DHCP snooping, and disabling unused ports to mitigate these attacks. These configurations aim to secure access layer switches and prevent malicious users from overloading the network.
Evaluation of shear strength of model rock joints by experimental studyeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The impact of the diameter to height ratio on the compressibility parameters ...eSAT Journals
Abstract Compressibility parameters of fine-grained soils are mainly influenced by soil mineralogy, moisture content and soil diameter to height ratio (D/H). The British and American standards suggested that to obtain accurate engineering properties; it is necessary to use D/H ratio of 4 and 2.5 respectively to eliminate friction between the soil and the structure. In the current study, various D/H ratios were adopted ranging from 0.5 to 11. The D/H ratios effect on some compressibility parameters such as coefficient of consolidation (cv), compression index (cc) and coefficient of volume compressibility (mv) were analysed. Additionally, the impact of the D/H ratio on the acquire cv values were also presented where three methods were used namely: Casagrande, Taylor and Inflection method. The scaling effects based on cv ratio [cv (√t) / cv (log t)] from Oedometer tests using different D/H ratios are also presented. The results showed that Taylor’s method is the most appropriate way to achieve an accurate cv and an increase in pressure leads to a reduction in cc and a gradual decrease in mv. The validation of the experimental results on a finite element software package PLAXIS was completed. Keywords: Compressibility, D/H ratio, Fine-grained soil, Friction
Low cycle biaxial fatigue behavior of direct aged Nickel-based 718 superalloy IJERA Editor
In recent years, significant advances in the fabrication process of nickel-base supperalloy leading to grain size
reduction have been made in order to improve fatigue properties of aircraft turbine discs. Indeed, a change in
particle size affects the initiation mode of fatigue cracks as well as the fatigue life of the material. The present
study aims to investigate the fatigue behavior of a newly developed nickel-based superalloy under biaxial-planar
loading. Low Cycle Fatigue (LCF) tests are performed at different stress ratios to study the influence of the
multiaxial stress state on the fatigue life of the material. Full-field displacement and strain measurements as well
as crack initiation detection are obtained using Digital Image Correlation (DIC) techniques. Results related to
different load ratios are presented and an appropriate biaxial lifetime prediction is given. Crack detection, strain
amplitude and number of cycles to crack initiation vs. triaxial stress ratio for each loading case are mentionned.
From fractographic investigations by scanning electron microscopy it is found that the mechanism of fatigue
crack initiation does not depend on the triaxial stress ratio and that most fatigue cracks initiate from subsurface
carbides.
Fatigue Study of Ijuk-Aren Interaction on Soil Cement Pavement Model for Elas...AM Publications
This document summarizes a study that examined the fatigue behavior of soil-cement mixtures with palm fiber reinforcement as a pavement material. Laboratory tests were conducted on sandy clay soil stabilized with 6% cement and 0% or 0.5% palm fibers by dry weight of soil. Repeated load testing was performed and resilient modulus and microstructural observations were analyzed. The results showed that 0.5% palm fiber reinforcement increased the resilient modulus degradation by 6.5% after 28 days. Microstructural observations indicated cement hydration bound soil particles and covered the surface of palm fibers, improving the strength of the soil-cement mixture. The fiber reinforcement improved the strength and longevity of the soil-cement pavement material.
This document describes research using a spectroscopic sensor and neural network model to monitor droplet size distributions (DSDs) in metal working fluid (MWF) emulsions. The sensor measured light absorption and scattering spectra of MWF samples. A neural network model was trained using spectroscopic data and reference DSD measurements. The model accurately estimated DSDs for new samples, distinguishing monomodal and bimodal distributions. This technique could monitor MWF emulsion aging and destabilization in industrial processes.
Spray Coated Nanocellulose Films Production Characterization and ApplicationKirubanandan Shanmugam
Spraying nanocellulose on a polished impermeable surface is a novel concept to produce a film which has two distinct surfaces. The spray coated surface is very smooth and replicates the nanoscale roughness from the base surface. This process reduces the operational time for film formation by one order of magnitude compared to vacuum filtration, which is the standard method. The spraying process was optimised to develop highly uniform sheets. The films were recyclable and sustainable. Spraying process has been successfully implemented to develop high performance nanocomposites for barrier applications and smooth films for electronics.
Flexibility Analysis In Industrial Piping Through The Finite Elements And Pho...IJERA Editor
This document analyzes the flexibility of industrial piping through finite element analysis, photoelasticity, and mathematical modeling. It presents the equations and properties used in each modeling method. The finite element model in ANSYS showed stress distributions that matched the mathematical model. The photoelasticity model allowed visualizing stress curves but values were difficult to obtain. The computational finite element model was determined to be best for industrial applications by providing reliable stress and deformation values and allowing complex analyses.
An experimental investigation on flexural behaviour of fibre reinforced robo ...eSAT Journals
Abstract Now a days due to many civil engineering constructions through out the globe the usage of natural sand is very large and so it is slowly becoming scarce. Because of this main reason in the present days the usage of Robo sand or Crushed or artificial sand has gained momentum. This paper presents a brief study on the flexural behaviour of fibre reinforced ferrocement elements made with artificial sand(Robo sand).Nearly 30 mortar cubes and 180 flexural specimens were cast and tested with the variables such as different percentages of steel fibre, number of wire mesh layers and different span to depth ratios (a/d) etc,. From the results it is observed that with the increase in percentage of fibres the compressive strength of mortar, first crack load, ultimate load in flexure, flexural stress at first crack load, flexural stress at ultimate load and energy absorption increase up to certain extent and afterwards get decreased. Also the above strength parameters are found to increase with number of wire mesh layers. More so the above strengths are found to decrease with the increase in a/d ratio except the flexural stresses at first crack load and ultimate load. Besides the paper presents the behaviour of load – deflection variation and crack pattern for number of variables studied. Further a comparative study of the behaviour of robo sand specimens with those of the natural sand has been studied. Finally an analytical model has been proposed for Mcr and Mu with the inclusion of the most of the variables used in the present investigation. Keywords: Robosand, Span to Depth ratio (a/d), Volume percentage of fibres (Vf), Number of Mesh Layers (N).
Damage detection in cfrp plates by means of numerical modeling of lamb waves ...eSAT Journals
Abstract
The paper presents an application of modeling acoustic waves propagation in a carbon fiber reinforced plastic (CFRP) plates for
damage detection. This task is a part of non-destructive testing (NDT) methods which are very important in many industry
branches. Propagation of Lamb waves is modeled using three-dimensional finite element method by means of commercial
software. In the paper three different cases of plate structures with and without flaws are considered to present review of selected
methods for the detection of defects in time and frequency domain. These are comparisons of: A-scans, B-scans, dispersion
curves, spectrograms, scalograms and energy plots. Developed numerical model first has been validated by means of analytical
solution for isotropic plate.
Keywords: Lamb waves, non-destructive testing, finite element method, damage detection
Investigation on effective thermal conductivity of foams using transient plan...eSAT Publishing House
The document describes an experimental setup used to determine the effective thermal conductivity of various foam materials (polyurethane foam, latex rubber foam, synthetic foam) using the transient plane heat source method. Thermal conductivity measurements were taken for each foam material at different concentrations (obtained by compressing the foam to different thicknesses). The results showed that increasing the concentration of the material (decreasing porosity) led to an increase in the effective thermal conductivity, as compressing the foam evacuated more of the low conductivity air pockets within the material.
THE INFLUENCE OF MICROSTRUCTURE IN THE HOMOGENEITY OF HARDNESS STANDARD BLOCKSTito Livio M. Cardoso
1. The document examines the influence of microstructural homogeneity on the uniformity of hardness values in hardness standard blocks.
2. Analysis of a certified 109 HB hardness standard found heterogeneous grain sizes and distributions, with some areas having much larger crystals than others.
3. Hardness measurements within coarse-grained areas showed values of 101 HB, significantly lower than the 108 HB measured in fine-grained areas. Excluding the outlier, the average was 108.5 HB, within specification.
4. The results demonstrate that microstructural heterogeneity can influence both the uniformity and magnitude of hardness values, which is particularly critical for certified reference materials like hardness standard blocks.
Tribologoical Properties of Vinyl Ester Based Hybrid Composite with Tio2, Al2...ijtsrd
This document summarizes a study on the tribological properties of vinyl ester-based hybrid composites filled with TiO2, Al2O3, and MoS2 particles. Pin-on-disc testing was conducted to evaluate the wear rate of composites with 7.5%, 10%, and 12.5% filler content under loads of 1KN, 2KN, and 3KN. The results showed that increasing the filler content decreased the wear rate, and increasing the load increased the wear rate. TiO2 filled composites exhibited the lowest wear rates compared to Al2O3 and MoS2 filled composites. Overall, adding filler particles improved the wear resistance of the vinyl ester matrix.
Estimation of flow accelerated corrosion (fac) in feeder pipes using cf dd so...Alexander Decker
This article summarizes a study on estimating flow accelerated corrosion (FAC) in feeder pipes of a nuclear reactor using computational fluid dynamics (CFD) software. The study had two objectives: 1) perform CFD analysis of a modeled feeder pipe using Fluent software to estimate maximum wall thinning, and 2) design an experimental setup to study FAC at low temperatures. The CFD analysis estimated a maximum wall thinning rate of 1.1 mm/year in a feeder pipe bend. Experimental tests on mild steel coupons in water at 90°C found corrosion rates up to 1.63 g/cm2/year but no evidence of FAC below this temperature.
This document presents a dimensional analysis of the sludge filtration process using a sand drying bed. The analysis derives an equation to model sludge filtration that incorporates the compressibility coefficient. Experimental data from a pilot-scale sand drying bed is used to validate the theoretical equation. The experimental and theoretical slopes and intercepts show close agreement, with correlation coefficients ranging from 0.94-0.98, validating the derived equation. The equation accounts for factors such as sludge compressibility believed to affect the filtration process.
Sensitivity of the MEMS based Piezoresistive Wind Speed Sensor with Comparati...IRJET Journal
This document presents a study comparing the sensitivity of a MEMS piezoresistive wind speed sensor using different shaped paddles (hexagonal, rectangular, triangular) through finite element analysis. The triangular paddle produced the highest stress levels and sensor sensitivity of 0.20402825 mV/ms-1. Simulation results showed that as wind speed increased from 20-40 m/s, stress, displacement, and sensor output voltage also increased, with the triangular paddle design performing best. The sensor was designed to detect wind speed changes through the resulting resistance changes in an on-chip piezoresistive layer.
This document discusses the gamma ray shielding and structural properties of PbO-BaO-P2O5 glass systems. Transparent glass samples were prepared with compositions of 55PbOxBaO(45-x)P2O5 (x = 1 to 5). Gamma ray shielding properties like mass attenuation coefficient and half value layer were calculated and compared to standard radiation shielding concrete. Characterization techniques like density, XRD, FTIR, Raman, UV-visible were used to study the structural properties and understand how the structure changes with the addition of BaO. The glass system showed improved gamma ray shielding with increasing BaO content and has potential to be a viable alternative to conventional concrete radiation shields
This document summarizes a numerical study of squeeze film dampers. Key points:
- Squeeze film dampers are used in turbomachinery to reduce vibration and improve stability by dissipating energy through viscous forces.
- A steady state solver was used to model the whirling motion of the rotor, allowing for more efficient computation compared to unsteady models.
- Results from simulations at 50Hz matched well with experimental pressure data, validating the steady state approach.
- Pressure and liquid fraction contours from the simulations showed the expected patterns, with high pressure before minimum clearance dropping rapidly afterward.
Computational fluid dynamics simulation of single screw extruders in cable in...eSAT Journals
Abstract The flow of polymer pellets along the solid conveying screw of a single screw extruder is studied by use of a numerical model
based on the Finite Volume Method (FVM). The screw profile of existing Nokia-Malifer plastic extrusion devices (for cable
industries) was mesured.Model predictions used is the Power law for Non-Newtonian Fluid, the results are compared with
experimental data, showing a good match. The feasiability of using CFD models for designing plastic extrusion devices is
analyzed. Basic parameters such as temperature, velocity profiles and pressure show high degree of similarity to practical results.
KeyWords: CFD, Single Screw Extruder, Ansys Fluent, Numerical Simulation
The document discusses particle coating using dry powder technology. It examines coating microcrystalline cellulose spheres using various modified polysaccharides in a pan coater. The pan coater achieved coating efficiencies of around 85%, higher than a Wurster bottom spray coater or rotary disk coater. Coating with polysaccharides like Matrix 2 and Matrix 3 produced a homogeneous, continuous coating layer. The dry coating process could provide innovative formulations for food and pharmaceutical applications while avoiding issues with solvent-based or aqueous coating methods.
The document discusses particle coating using dry powder technology. It examines coating microcrystalline cellulose spheres using various modified polysaccharides in a pan coater. The pan coater achieved coating efficiencies around 85% while other equipment like the Wurster bottom spray coater and rotary disk coater had much lower efficiencies below 5% and around 0% respectively due to issues like powder loss and abrasion. The modified polysaccharides Matrix 2 and Matrix 3 produced the most homogeneous coatings with a continuous film. Dry particle coating using a pan coater and these polysaccharides is a promising environmentally friendly method for applications in food and pharmaceuticals.
A Study of Pulse by Pulse Microscale Patch Transfer Using Picosecond LaserIJERA Editor
This document summarizes a study on using picosecond laser-induced forward transfer to deposit Ti/Ni shape memory alloy patches with high precision on a substrate. The researchers investigated how laser power and distance between the donor film and substrate affect the size of deposited patches. They found that spot size decreases linearly with lower laser power but has a non-linear relationship with distance, initially increasing then decreasing. Repeated deposits showed similar Ti/Ni composition, demonstrating the feasibility of precisely depositing smart materials for applications like active molds for micro-injection molding.
Similar to Properties of the cake layer in the ultrafiltration of polydisperse colloidal silica dispersions (20)
Hudhud cyclone caused extensive damage in Visakhapatnam, India in October 2014, especially to tree cover. This will likely impact the local environment in several ways: increased air pollution as trees absorb less; higher temperatures without tree canopy; increased erosion and landslides. It also created large amounts of waste from destroyed trees. Proper management of solid waste is needed to prevent disease spread. Suggested measures include restoring damaged plants, building fountains to reduce heat, mandating light-colored buildings, improving waste management, and educating public on health risks. Overall, changes are needed to water, land, and waste practices to rebuild the environment after the cyclone removed green cover.
Impact of flood disaster in a drought prone area – case study of alampur vill...eSAT Publishing House
1) In September-October 2009, unprecedented heavy rainfall and dam releases caused widespread flooding in Alampur village in Mahabub Nagar district, a historically drought-prone area.
2) The flood damaged or destroyed homes, buildings, infrastructure, crops, and documents. It displaced many residents and cut off the village.
3) The socioeconomic conditions and mud-based construction of homes in the village exacerbated the flood's impacts, making damage more severe and recovery more difficult.
The document summarizes the Hudhud cyclone that struck Visakhapatnam, India in October 2014. It describes the cyclone's formation, rapid intensification to winds of 175 km/h, and landfall near Visakhapatnam. The cyclone caused extensive damage estimated at over $1 billion and at least 109 deaths in India and Nepal. Infrastructure like buildings, bridges, and power lines were destroyed. Crops and fishing boats were also damaged. The document then discusses coping strategies and improvements needed to disaster management plans to better prepare for future cyclones.
Groundwater investigation using geophysical methods a case study of pydibhim...eSAT Publishing House
This document summarizes the results of a geophysical investigation using vertical electrical sounding (VES) methods at 13 locations around an industrial area in India. The VES data was interpreted to generate geo-electric sections and pseudo-sections showing subsurface resistivity variations. Three main layers were typically identified - a high resistivity topsoil, a weathered middle layer, and a basement rock. Pseudo-sections revealed relatively more weathered areas in the northwest and southwest. Resistivity sections helped identify zones of possible high groundwater potential based on low resistivity anomalies sandwiched between more resistive layers. The study concluded the electrical resistivity method was useful for understanding subsurface geology and identifying areas prospective for groundwater exploration.
Flood related disasters concerned to urban flooding in bangalore, indiaeSAT Publishing House
1. The document discusses urban flooding in Bangalore, India. It describes how factors like heavy rainfall, population growth, and improper land use have contributed to increased flooding in the city.
2. Flooding events in 2013 are analyzed in detail. A November rainfall caused runoff six times higher than the drainage capacity, inundating low-lying residential areas.
3. Impacts of urban flooding include disrupted daily life, damaged infrastructure, and decreased economic activity in affected areas. The document calls for improved flood management strategies to better mitigate urban flooding risks in Bangalore.
Enhancing post disaster recovery by optimal infrastructure capacity buildingeSAT Publishing House
This document discusses enhancing post-disaster recovery through optimal infrastructure capacity building. It presents a model to minimize the cost of meeting demand using auxiliary capacities when disaster damages infrastructure. The model uses genetic algorithms to select optimal capacity combinations. The document reviews how infrastructure provides vital services supporting recovery activities and discusses classifying infrastructure into six types. When disaster reduces infrastructure services, a gap forms between community demands and available support, hindering recovery. The proposed research aims to identify this gap and optimize capacity selection to fill it cost-effectively.
Effect of lintel and lintel band on the global performance of reinforced conc...eSAT Publishing House
This document analyzes the effect of lintels and lintel bands on the seismic performance of reinforced concrete masonry infilled frames through non-linear static pushover analysis. Four frame models are considered: a frame with a full masonry infill wall; a frame with a central opening but no lintel/band; a frame with a lintel above the opening; and a frame with a lintel band above the opening. The results show that the full infill wall model has 27% higher stiffness and 32% higher strength than the model with just an opening. Models with lintels or lintel bands have slightly higher strength and stiffness than the model with just an opening. The document concludes lintels and lintel
Wind damage to trees in the gitam university campus at visakhapatnam by cyclo...eSAT Publishing House
1) A cyclone with wind speeds of 175-200 kph caused massive damage to the green cover of Gitam University campus in Visakhapatnam, India. Thousands of trees were uprooted or damaged.
2) A study assessed different types of damage to trees from the cyclone, including defoliation, salt spray damage, damage to stems/branches, and uprooting. Certain tree species were more vulnerable than others.
3) The results of the study can help in selecting more wind-resistant tree species for future planting and reducing damage from future storms.
Wind damage to buildings, infrastrucuture and landscape elements along the be...eSAT Publishing House
1) A visual study was conducted to assess wind damage from Cyclone Hudhud along the 27km Visakha-Bheemli Beach road in Visakhapatnam, India.
2) Residential and commercial buildings suffered extensive roof damage, while glass facades on hotels and restaurants were shattered. Infrastructure like electricity poles and bus shelters were destroyed.
3) Landscape elements faced damage, including collapsed trees that damaged pavements, and debris in parks. The cyclone wiped out over half the city's green cover and caused beach erosion around protected areas.
1) The document reviews factors that influence the shear strength of reinforced concrete deep beams, including compressive strength of concrete, percentage of tension reinforcement, vertical and horizontal web reinforcement, aggregate interlock, shear span-to-depth ratio, loading distribution, side cover, and beam depth.
2) It finds that compressive strength of concrete, tension reinforcement percentage, and web reinforcement all increase shear strength, while shear strength decreases as shear span-to-depth ratio increases.
3) The distribution and amount of vertical and horizontal web reinforcement also affects shear strength, but closely spaced stirrups do not necessarily enhance capacity or performance.
Role of voluntary teams of professional engineers in dissater management – ex...eSAT Publishing House
1) A team of 17 professional engineers from various disciplines called the "Griha Seva" team volunteered after the 2001 Gujarat earthquake to provide technical assistance.
2) The team conducted site visits, assessments, testing and recommended retrofitting strategies for damaged structures in Bhuj and Ahmedabad. They were able to fully assess and retrofit 20 buildings in Ahmedabad.
3) Factors observed that exacerbated the earthquake's impacts included unplanned construction, non-engineered buildings, improper prior retrofitting, and defective materials and workmanship. The professional engineers' technical expertise was crucial for effective post-disaster management.
This document discusses risk analysis and environmental hazard management. It begins by defining risk, hazard, and toxicity. It then outlines the steps involved in hazard identification, including HAZID, HAZOP, and HAZAN. The document presents a case study of a hypothetical gas collecting station, identifying potential accidents and hazards. It discusses quantitative and qualitative approaches to risk analysis, including calculating a fire and explosion index. The document concludes by discussing hazard management strategies like preventative measures, control measures, fire protection, relief operations, and the importance of training personnel on safety.
Review study on performance of seismically tested repaired shear wallseSAT Publishing House
This document summarizes research on the performance of reinforced concrete shear walls that have been repaired after damage. It begins with an introduction to shear walls and their failure modes. The literature review then discusses the behavior of original shear walls as well as different repair techniques tested by other researchers, including conventional repair with new concrete, jacketing with steel plates or concrete, and use of fiber reinforced polymers. The document focuses on evaluating the strength retention of shear walls after being repaired with various methods.
Monitoring and assessment of air quality with reference to dust particles (pm...eSAT Publishing House
This document summarizes a study on monitoring and assessing air quality with respect to dust particles (PM10 and PM2.5) in the urban environment of Visakhapatnam, India. Sampling was conducted in residential, commercial, and industrial areas from October 2013 to August 2014. The average PM2.5 and PM10 concentrations were within limits in residential areas but moderate to high in commercial and industrial areas. Exceedance factor levels indicated moderate pollution for residential areas and moderate to high pollution for commercial and industrial areas. There is a need for management measures like improved public transport and green spaces to combat particulate air pollution in the study areas.
Low cost wireless sensor networks and smartphone applications for disaster ma...eSAT Publishing House
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Properties of the cake layer in the ultrafiltration of polydisperse colloidal silica dispersions
1. IJRET: International Journal of Research in Engineering and Technology eISSN:2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Issue: 10 | Oct-2014, Available @ http://www.ijret.org 233
PROPERTIES OF THE CAKE LAYER IN THE ULTRAFILTRATION
OF POLYDISPERSE COLLOIDAL SILICA DISPERSIONS
N.H. Ramli1
, A. Lord2
, L. Powell3
, P.M. Williams4
1
Faculty of Chemical and Natural Resources Engineering, University Malaysia Pahang, Tun Razak Highway, 26300
Kuantan, Pahang, Malaysia
2
Multidisciplinary Nanotechnology Centre, Swansea University, Swansea, SA2 8PP, UK
3
Multidisciplinary Nanotechnology Centre, Swansea University, Swansea, SA2 8PP, UK
4
Multidisciplinary Nanotechnology Centre, Swansea University, Swansea, SA2 8PP, UK
Abstract
The properties of the cake layer formed during the ultrafiltration of polydisperse silica colloid using the Karman Cozeny equation
have been studied and are compared to the experimental results obtained from SEM and AFM analysis. AFM analysis is used to
give a direct comparison to SEM analysis in order to give a better understanding of the cake properties formed at different
compositions and different pH’s. The trend of the filtration rate of binary mixtures of silica particles (W30 and X30) were
analysed and correlated to the results of the specific resistance obtained from SEM analysis. The study involves analysing the
fouled membrane from the top view and from the cross sectional view. This present work has found that results from the SEM and
AFM analysis corresponded to each other in terms of particle arrangement and the average cake thickness.
Keywords: polydisperse; cake resistance, colloidal -interaction
------------------------------------------------------------------***--------------------------------------------------------------------
1. INTRODUCTION
Ultrafiltration is one of the pressure driven membrane
separation processes which has been commercially used in
many industries including the pharmaceutical, dairy, and
dye industries. This type of the membrane process is capable
of separating the solutes with a molecular weight greater
than 1000 Da (Coulson et al. 2002). Many works have been
reported on the flux decline in ultrafiltration (Bowen and
Jenner 1995; Bowen and Williams 1996a; Shen and
Probstein 1977; Wijman et al. 1984) but only a few studies
have been reported in the literature on modelling the
behaviour of polydisperse feeds containing suspended
colloidal particles (Dickinson 1979; Dickinson et al. 1988;
McDonogh et al. 1998). Studies on the effect of
polydispersity on the rate of filtration have been conducted
by researchers in order to introduce a new parameter into the
classic filtration model to consider for polydispersity effect
(Mc Donogh et al. 1998, Dickinson, 1979). There are two
approaches which can be used to include the effect of
polydispersity which are the Resistance Model as introduced
by McDonogh et al. (1998) or the Osmotic Pressure Model
used by Dickinson (1979. In this work, the effect of
polydispersity is examined in terms of a resistance model by
estimating the specific cake resistance directly from the
filtration rate and the cake layer thickness analysis under the
SEM.
The application of the SEM for membrane characterisation
has played an important role in membrane development and
fouling control. SEM analysis enables investigation of the
separation characteristics and the mechanical strength of the
membrane, which are controlled by the surface morphology
and chemical make up of the membrane. Performance of the
developed membrane can be optimized by knowing some
useful information observed in a SEM. Many works have
been reported on the SEM analysis for membrane
characterization (Kim et al. 2006; Madaeni 1998a; Madaeni
1998b; Meng et al. 2005; Schossig-Tiedemann and Paul
2001; Wickramasinghe et al. 2009; Ziel et al. 2008).
A number of studies have been conducted on AFM
characterization related to membrane analysis (Bessibres et
al. 1996; Binning et al. 1982; Bowen et al. 1996a; Bowen et
al. 1996b; Bowen et al. 1998a; Bowen et al. 1998b). The
AFM can be used to give high resolution nanometer scale
images of the topography of a range of surfaces with little
surface preparation and no surface coating. AFM imaging
technology has been utilised for the quantification of surface
morphology, pore size distributions and surface roughness
for various types of membranes, such as NF, RO and UF
(Bowen and Doneva, 2000, Norberg et al. 2007, Vrijenhoek
et al. 2001). However no study has investigated the cross-
section of flat sheet membrane by AFM, with the majority
of research groups utilising SEM for cross-sectional
membrane characterisation. Khulbe et al. (2006) examined
the cross-section of polyetherimide hollow fibers prepared
by two methods using AFM, however due to difficulties in
sample preparation only 3µm images of the fibers could be
obtained. In this present study, the morphology, roughness
and peak-to-valley height of the cross-section of the flat
sheet membrane complete with cake layers were studied by
AFM and compared to the findings observed from the SEM
analysis.
2. IJRET: International Journal of Research in Engineering and Technology eISSN:2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Issue: 10 | Oct-2014, Available @ http://www.ijret.org 234
2. THEORETICAL ASPECTS
2.1 Cake Resistance Model
The basic flux equation is given by equation 1 in which flux
decline is controlled by applied pressure difference and
resistance.
.
1
m c m
P dV
J
R R A dt
(1)
However, many researchers agreed that osmotic pressure
can be ignored if the cake resistance is already considered in
the model (Bowen and Jenner, 1995, Bowen and Williams
1996). The cake resistance model is described by equation
(2) where the osmotic pressure term is eliminated from
equation 1
1
m s m
p dV
J
R R A dt
(2)
where,
b
c
m
VC
R
A
(3)
The relationship between Darcy’s Law and Carman Kozeny
is used to express , in which is the specific resistance
of the deposited mass.
2 3
180 1
p sd
(4)
where is void volume, p is the particle density, sd is the
mean particle diameter, V and mA are the total filtered
volume and membrane area respectively.
Wutzel and Samhaber (2009) have modified the filtration
theory of equation to take into account the cake thickness
, formed during the process
m c m
1 dV P
A dt ( R )
(5)
where c represents the specific resistance of the cake layer
and mR is the resistance of the membrane. The thickness of
the porous cake layer can rewritten as,
The thickness of the porous cake layer can rewritten as,
p m
m
A (1 )
(6)
where m is the mass of the layer, p is the particle density
and is the porosity of the layer. , the specific resistance
of the deposited mass is defined by the Carman Kozeny law
(Carman, 1938) as described in Equation (4).
However equation (4) is only applicable for monodisperse
system. Endo and Alonso (2001) have proposed a theoretical
model of cake filtration in the laminar flow regime which is
applicable for polydisperse systems. The model assumes the
cake consists of non-spherical particles with a log-normal
size distribution. This results in an alteration of Equation (4)
to:
2 2
p vg g
180 (1
d exp(4ln )
(7)
where is a shape factor (which is equal to 1 for spheres),
dvg is the geometric mean diameter of dp on a number basis
and g is the geometric standard deviation. If the particles
are monodisperse Equation (7) becomes identical to
Equation (4).
The parameters, dvg and g can be calculated using:
i
ipi
vg
n
dn
d
ln
exp (8)
i
vgii
g
n
ddn 2
)]/[ln(
exp (9)
The specific resistance, is calculated from the slope of the
plot of t/V versus V, where the gradient is defined as:
b c
2
m
C
gradient
2A P
(10)
Therefore, porosity can be predicted by using Equations (7)-
(10) , and the porosity can be substituted into equation (6) to
estimate the thickness of the cake layer form in the filtration
process. The combination of cake thickness and the specific
cake resistance can be used to calculate the cake resistance.
Note that, cake resistance cR is described in Equation (3),
and the cake volume term in Equation (3) shown above can
be determined as
mV A (11)
Substituting Equation (11) into Equation (3) yields:
c c bR C (12)
3. IJRET: International Journal of Research in Engineering and Technology eISSN:2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 10 | Oct-2014, Available @ http://www.ijret.org 235
The aim of the presents work is to investigate the influence
of polydispersity to the cake resistance properties. For these
reasons the fouled membrane is observed under the SEM
and AFM to investigate the particle arrangement and the
thickness of the cake layer deposited on the membrane due
to the variation in the feed composition and pH change.
3. EXPERIMENTAL
3.1 Silica Dispersion
Sodium chloride electrolyte solutions were made by
dissolving a weighed amount of sodium chloride, obtained
from Fisons Scientific Equipment (Grade:- Fisons AR), in
high purity water (produced by a Millipore Elix 3 system) to
make a solution of the required ionic strength. The ionic
strength of the electrolyte used was verified from specific
conductivity measurements performed using a Portec PI-
8140 digital conductivity meter in connection with a Philips
conductivity cell (type: 4550/60).
The colloidal particles used were W30 and X30 colloidal
silica (purchased from Morrisons Gas Related Products Ltd).
These came as liquid dispersions with the following
properties: concentration 30 % by weight, dispersion
medium 0.03M NaCl solution (plus other stabilizers) at
pH 9.5, particle diameter X30 15 nm, W30 50 nm. The
exact concentration of this stock solution was determined in
the following manner. Five petri dishes were taken and
weighed using an electronic balance (Mettler Toledo P303
Delta Range, accurate to 0.001g). A known amount of the
stock silica solution was then added to each petri dish. The
dishes were then placed in an oven set at 120C and left
overnight to dry. The dishes were then weighed again the
following day and the difference between this new weight
and the clean petri dish weight was found. This corresponds
to the mass of dry silica in the solution. The mass weight %
was then found by dividing the weight of dry silica by the
total solution weight. Finally, the average value of the five
measurements was taken and used subsequently as the
concentration of the stock silica solution. Dilutions of this
stock solution were made by adding known amounts of
0.03M NaCl to a known mass of the stock silica solution.
The pH of the final silica solution was adjusted to the
desired value by the dropwise addition of NaOH and HCl
(both of Grade:- Fisons AR). The pH measurements were
carried out using a Philips PW 9421 digital high precision
pH meter (pH resolution 0.01) in connection with a Russell
CMAWL/4/5 pH probe.
3.2 Size Measurements
Dynamic light scattering measurements were performed
with a Malvern HPPS system (Malvern Instruments Limited,
UK). The light source was an Argon laser operating with
vertically plane polarised light at a wavelength of 488 nm.
All the dynamic light scattering measurements were carried
out at a low laser power (~ 13.3 mW), so the results are not
influenced by local heating of the samples which would be
caused by use of a more powerful beam. The scattering
angle used was 90. The temperature of the samples was
automatically kept at 25.0 0.1 C. Prior to each
experiment, the measurement cell was flushed with high-
purity water to remove dust in the cell. Dynamic light
scattering measurements were performed on 4g/L silica
dispersions in 0.03M NaCl at various pH values. Only
solutions containing 100% W30 or 100% X30 were used for
these experiments. The data measured was analysed
according to BS 3406 (1997) in order to determine the
particle size.
3.3 Zeta Potential Measurements
The same silica dispersions as used for the size
measurements were used for the electrophoretic mobility
measurements. Electrophoretic mobility measurements were
made using a Zetasizer 2000 (Malvern Instruments, UK).
Electrophoretic mobility values were converted to zeta-
potentials using the WinMobil programme (Department of
Mathematics, University of Melbourne) which is an
extended implementation of an advanced theory of
electrophoresis (O’Brien and White, 1978).
3.4 Filtration
Filtration measurements were carried out using a 50 mL
filtration cell (Amicon Corp., Model 8050) connected to a
reservoir with a maximum capacity of 250 mL. The
effective membrane area was 13.4 cm2
. The system was
pressurised with nitrogen gas and the cell was not stirred.
The temperature of the system was kept constant at 25.0
0.1 C via a water jacket on the filtration cell and a water
bath around the reservoir. The filtration time was coupled to
the amount of permeate collected - experiments were
stopped usually after 25 - 30 mL of permeate was collected.
The total filtration time was therefore in the range of 1 - 3
hours, depending on the solution conditions. Rates of
filtration were determined by continuously weighing the
filtrate on an electronic balance connected to a micro-
computer.
NADIR polyethersulphone membranes of molecular weight
cut-off 4000D were obtained from MICRODYN-NADIR
GmbH (Germany). Before use the membrane was cleaned
using pure water and then soaked for at least 16 hours. The
hydraulic resistance of the NADIR 4000D membrane discs
was determined by filtration of pure electrolyte solution
through the membrane. The clean water flux or solvent flux
rates are determined by filtering the water/electrolyte alone
through a fresh membrane at five different pressures (50,
100, 200, 300 and 400 kPa) until 20 mL of permeate sample
is collected at each pressure.
Filtrations were then carried out on silica solutions
containing a total silica concentration of 4g/L. These
solutions consisted of a 0.03M NaCl electrolyte with the
following mixing ratio of X30:W30 by weight: (i) 100%
X30, (ii) 100% W30, (iii) 20%:80% (iv) 40%:60%, (v)
60%:40% and (vi) 80%:20%. The filtration experiments
were repeated at least three times to confirm the validity of
the experimental data.
4. IJRET: International Journal of Research in Engineering and Technology eISSN:2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Issue: 10 | Oct-2014, Available @ http://www.ijret.org 236
3.5 SEM Analysis
3.5.1 Solution Properties
The properties of the feed solution for W30 and X30
solutions were observed under a SEM machine (Model
S4800 Hitachi). A drop of the diluted solution (with a
concentration 0.1g/L) was placed onto a silicon wafer and
spread evenly using a spin coater (GME Limited, PRS14E).
The sample was dried using a hot plate (Stuart Scientific)
before being imaged with the SEM. A low concentration of
solution was required for the purpose of imaging the
characteristics of the silica particles on the silicon wafer
surface in order to reduce charging problems during the
imaging process so that a high resolution image can be
obtained. The measurement of the individual particle size of
silica particles under the SEM can also be done easily as the
low concentration solution avoids particles from being
clumped to each other.
3.5.2 Clean Membrane Properties
The clean NADIR 4000D MWCO membrane used in the
dead-end filtration experiments was imaged under the SEM.
A fresh and cleaned membrane was initially soaked
overnight in water. The membrane was then compacted in a
filtration experiment using a NaCl electrolyte solution of
0.03M concentration and pressurised at 200kPa until 15mL
of permeate solution was collected. The membrane was
removed and square fragments with an area of several
square milimeters were cut out of the membrane. Cutting of
the membrane was greatly aided by freezing in liquid
nitrogen for a few minutes which makes the sample brittle.
The square fragments of membrane were then adhered to the
SEM’s aluminium sample stub using standard microscopy
silver paint and dried at room temperature.
3.5.3 Fouled Membrane Properties
At the end of the dead end filtration experiments where
colloidal silica solutions were used as the feed solution, the
fouled membrane was removed from the filtration cell. The
filtration was stopped when the volume of permeate solution
reached about 15 to 20 mL. This ensured that the cake
formed under constant pressure. Again, the sample was
frozen in liquid nitrogen, fractured into small fragments and
stuck on the SEM sample stub using silver paint with the
surface of the cake layer facing upwards. As the sample
consisted of nonconductive material, the deceleration mode
at 1.5kV current was applied when observing the sample
under the SEM to reduce the charging problem.
Topographical and cross sectional imaging analysis of the
fouled membrane was carried out at different feed
compositions depending on the trend of filtration seen in the
previous work (Ramli and Williams 2012, Ramli 2012)
3.6 AFM Analysis
Similar to SEM, AFM was used to observe the fouled
membrane from two different perspectives which are the
topographical view and cross sectional view. The properties
of the solutions (W30 and X30) and the clean membrane
were imaged under the AFM initially. This preliminary
experimental work was required in order to get information
on the active layer and support layer of the membrane along
with the silica properties.
3.6.1 Experimental Procedure
The Dimension 3100 AFM (Digital Instruments – Veeco
Metrology group, Santa Barbara, California) and non
contact cantilevers (RTESPA, Veeco) were used for cross-
sectional membrane imaging. The membrane images were
obtained using tapping mode, at a scan rate of 0.5Hz and an
image resolution of 512 x 512 pixels. However, for the
largest scan size of 60 60 μm2, a scan rate of 0.3Hz was
used to achieve a higher quality image. The captured images
were analysed using Nanoscope offline software. The mean
measurements of the software computed Peak-to-Valley
height and Root-mean-square (RMS) roughness, from eight
10 10 μm2 images of the silica covered membrane.
3.6.2 Solution Properties
Properties of the W30 and X30 particles were observed
under the AFM. A drop of the stock silica solution was
diluted with 300 mL of deionised water. Then a drop of this
diluted solution was taken and deposited on a glass slide and
dried at room temperature before being analysed under the
AFM.
3.6.3 Clean Membrane Properties
Analysis of the clean membrane under the AFM is straight
forward, where the dry membrane was cut into square
fragments with an area of several square milimeters and
stuck on a glass slide using double sided tape with the active
layer facing upwards.
3.6.4 Fouled Membrane Properties
For cross sectional analysis the sample was prepared in the
same way as the SEM samples by fracturing a small part of
the membrane in liquid nitrogen. The cross sectional sample
was fixed in a vertical position on the glass slide using
double sided tape, with the exposed part of the membrane
facing upwards. Then the membrane sample was
sandwiched between two glass slides to stabilize the sample
for AFM imaging (Ramli 2012).
4. RESULTS AND DISCUSSION
4.1 Solution Characteristic
The particle size and zeta potential results are shown in
Table 1 for the X30 and W30 colloidal silica. Table 1 shows
that W30 is approximately 3.3 times the size of X30. Ten
measurements were made on each sample at pH 4, 6 and 9
and the average of all these measurements are shown in
Table 1, as there is no appreciable difference in size between
the measurements made at the three different pH values.
Table 5.1 also shows the zeta potentials measured at the
different pH values. The zeta potential values are an average
of at least 35 measurements on each sample. The magnitude
of the zeta potential of W30 at pH 9 is appreciably higher
than the value for X30 (by~ 10mV), whilst at pH 6 the
values are similar.
5. IJRET: International Journal of Research in Engineering and Technology eISSN:2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 10 | Oct-2014, Available @ http://www.ijret.org 237
Table 1: Size and zeta potential results for X30 and W30
colloidal silica in a 0.03M NaCl electrolyte solution (the
values show the standard deviation away from the average
value).
X30 W30
Particle Diameter
(nm)
15.6 0.9 51.7 1.7
Zeta Potential
(mV)
pH 4 -15.9 1.4 -7.2 1.2
pH 6 -29.4 3.3 -29.8 1.4
pH 9 -89.3 5.9 -98.3 7.3
Figure 1 (a-d) illustrates the images of silica particles
contained in W30 and X30 solutions as viewed under SEM
(Figures 1a and b) and AFM (Figure 1c and d). Figure 1a&c
shows that the W30 solution is found to be polydisperse in
nature from the SEM and AFM results.
Fig 1: Solution characteristics for W30 and X30 viewed under the SEM for a) W30 and b) X30 , and the AFM for c)W30 and
d)X30
This finding contradicts the work by Bowen and Jenner
(1995) who assumed that the W30 solution is a
monodisperse system, a result which was also found within
the work in Ramli and Williams (2012). The reason for this
is due to the limitations in using dynamic light scattering to
analyse the particle size in the solution
4.2 Filtration Results
Figure 2(a)-(c) depicts the normalized filtration rate of
binary mixtures W30 and X30 silica at pH 9, pH 6 and pH 4,
respectively (Ramli and Williams 2012). Normalized data is
obtained by eliminating the effect of the hydraulic
membrane resistance of the clean membrane, which is
determined from the flux rate of the clean membrane using
the electrolyte alone. Figure 2(a) shows the fastest filtration
is given by 100% composition of W30. The slowest
filtration rate was exhibited by the 100% composition of
X30. The rate of filtration decreased gradually as the amount
of X30 added increased. As the magnitude of the zeta
potential for both types of silica particle is very high (> 80
mV), the filtration is controlled by the interactions between
the particles rather than the way in which the particles pack
(Ramli and Williams 2012).
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Fig 2: Normalised flux for the filtration of silica binary
mixtures (X30 and W30) at a) pH 9, b) pH 6 and c) pH 4
A different pattern of filtration rates is seen for the filtration
at pH 6 as shown in Figure 2(b). The fastest filtration is
given by 100% composition of X30. The filtration rate of
W30 is slower but is not the slowest value seen. When a
small amount of X30 is added to W30 i.e. 20 % by weight,
the filtration rate of this solution is markedly slower than the
filtration rates of 100% W30 and 100%X30 (Ramli and
Williams 2012). This is likely to be due to the filling of
interstices in W30 filter cake in the bidisperse mixture
(McDonogh et al. 1998).
Figure 2(c) shows the normalized results for the binary
mixtures of X30 and W30 silica at pH 4. The 100% W30
and 100% X30 give similar filtration rates in this case.
Again, as with the data at pH 6, addition of a small amount
of X30 to the feed solution causes a sharp decrease in the
filtration rate, most likely due to the reasons as discussed for
pH 6. The 80% and 60% by weight W30 feed solutions give
similar slow filtration rates, whilst the 40% and 20% by
weight W30 feed solutions gave intermediate filtration rates
between the extremes.
4.3 Properties of the Cake Layer under SEM
Analysis
Figures 3 (a)&(d) illustrate SEM images of the clean and
fouled membrane. The reason for imaging the clean
membrane prior to use is in order to get information on the
active layer and support on the membrane under the SEM.
Therefore, the cake thickness measurement does not include
the support layer together. In Figure 3(c), the thickness of
the cake layer can be seen by knowing that the support layer
has more porous and uniform structure. In this work, the
same imaging procedures were repeated at each condition
(at pH 4, 6 and 9) and are summarised in the Tables (1)-(3).
This analysis was only carried out at the compositions which
gave the maximum, intermediate and minimum filtration
rates as shown in Figures 2(a)-(c).
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Fig 3: SEM images of clean and fouled membrane; a)clean
b) cake thickness and c) silica particle arrangement
4.3.1 At pH 9
For pH 9, SEM observation is carried out for three feed
compositions which are; 100%W30, 20%W30and 80%X30,
and 100%X30 in order to investigate significant effect of the
cake properties on the filtration rate. Table 2 summarizes the
overall properties of the cake measured experimentally and
predicted from theory at pH 9 at various different
compositions. There is a huge difference between the
calculated and measured cake thickness shown in Table 2.
The measured thickness is much less than the predicted
value calculated from the mass balance. There are two
reasons why this might be the case. First, the cake might
have been washed off during the sample preparation, or
came off from the surface when the membrane has been
fractured in liquid nitrogen during the sample preparation.
Second, there is also a possibility that the cake shrinks under
the vacuum pressure in the SEM machine. The estimated
thickness was calculated based on the mass balance for
filtering 20 mL of the feed through the membrane without
considering any other phenomena.
The cake resistance calculated from the mass balance and
filtration rate data are quite comparable to each other and
both resistances increase as the X30 concentration increased
in the feed solution. This corresponds with the filtration
trends shown in Figure 2(a) where 100% W30 gives the
fastest filtration rate at pH 9. However, the resistance
calculated from the cake thickness (thickness from SEM
images) contradicts these trends. This is very likely to be
due to the difficulty of preparing the samples for SEM
image observation.
Table 2: Properties of the cake layer obtained at pH 9, 0.03M NaCl.
Sample
Estimated
Porosity
Estimated
Thickness
(μm)
Actual
Thickness
(μm)
Cake Resistance
1
cR ( m )
from mass
balance
13 -1
×10 (m )
from
filtration
rate
13 -1
×10 (m )
from
cake
thickness
11 -1
×10 (m )
100%W30 0.303 38.93 0.22±0.04 4.66 5.54 2.63
20%W30 0.552 60.57 0.26±0.03 5.07 6.62 2.18
0%W30 0.549 60.17 0.13±0.02 5.43 6.82 1.17
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4.3.2 At pH 6
SEM analysis for cake formation at pH 6 was carried out at four different compositions which were 100% W30, 80% W30, 20%
W30 and 100% X30.
Table 3: Properties of the cake layer obtained at pH 6, 0.03M NaCl
Sample
Estimated
Porosity
Estimated
Thickness
(μm)
Actual
Thickness
(μm)
Cake Resistance
1
cR ( m )
from mass
balance
13 -1
×10 (m )
from
filtration
rate
13 -1
×10 (m )
from
Cake
thickness
11 -1
×10 (m )
100%W30 0.228 35.15 0.32±0.05 11.4 10.3 10.4
80%W30 0.354 42.01 0.51±0.08 13.7 12.1 16.7
20%W30 0.447 49.07 0.34±0.01 11.8 9.34 8.15
0%W30 0.471 51.3 0.11±0.05 10.1 9.67 2.18
Table 3 summarizes the cake properties at various
compositions for pH 6 in a 0.03M NaCl electrolyte solution.
Again, the estimated thickness was much bigger than the
measured thickness. Overall, the cake seen at this pH was
more compact when compared to the cake observed at pH 9.
Madaeni (1998b) reported that increasing pH causes a slight
increase in flux, due to the extra charge gained by the
particles when the pH increases causing greater porosity in
the cake leading to a reduction in resistance. From the
resistances calculated in Table 3, the maximum value of
resistance was obtained for the 80% W30 sample, which
gave the slowest filtration (see Figure 2(b)). This can be
explained by the filling interstices effect which was more
prominent at this composition due to the difference in
particle size distribution and surface charge effects present
between the particles. The estimated porosity increases with
an increase in the X30 composition as shown in Table 3.
This was correlated to the reduction in cake resistance
calculated from the cake measurement, theory and flux
experiments due to the increase in voids when more X30
particles are present.
4.3.4 At pH 4
For pH 4, the trend of filtration was similar to the trend seen
at pH 6 (see Figures 2(b&c). Therefore, samples with the
same compositions which are 100% W30, 80% W30, 20%
W30 and 100% X30 were observed under the SEM.
Table 4: Properties of the cake layer obtained at pH 4, 0.03M NaCl.
Sample
Estimated
Porosity
Estimated
Thickness
(μm)
Actual
Thickness
(μm)
Cake Resistance
1
cR ( m )
from mass
balance
13 -1
×10 (m )
from
filtration
rate
13 -1
×10 (m )
from
Cake
thickness*f
11 -1
×10 (m )
100%W30 0.215 34.57 0.12±0.02 14.7 12.5 5.09
80%W30 0.329 40.44 0.79±0.09 17.9 17.4 35.0
20%W30 0.405 45.61 0.41±0.08 17.1 12.7 15.4
0%W30 0.418 46.63 0.15±0.02 16.2 11.9 5.21
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Table 4 summarizes the cake properties observed at pH 4 at
various compositions. As expected, the resistance calculated
from the theory and filtration experiment has shown that the
resistance at 80% and 60% W30 were very close to each
other and gave the maximum resistance when compared to
the other compositions. This prediction agrees well with the
filtration rate results shown in Figure 2(c) where these two
values gave the slowest filtration rate. The same happened
with the resistance measured from the cake thickness where
the 80% W30 solution gave the maximum value compared
to the other compositions. However, the data for the cake
resistance at 60% W30 is not available as no cake thickness
measurement has been made at this composition as a similar
filtration rate to the 80% W30 results was shown (see Figure
2(c)).
The thickness measurement of the cake layer shows that at
80%W30 composition at pH 4, the cake layer thickness was
55% greater when compared to the cake layer obtained at
pH 6 for the same composition. Hence, the porosity
calculated at this pH is even smaller when compared to pH
6. This was caused by the agglomeration phenomenon
between the smaller particles compared to the filling void
effect, resulting in the cake becoming thicker and more
porous. For these reasons the resistance calculated at pH 4 is
greater than the resistance calculated at pH 6. However, the
estimated thickness from theory has shown that the cake
obtained at pH 4 is thinner than that obtained at pH 6. This
was due to the estimation by the theory being calculated
only via the mass balance and measured porosity without
considering any other phenomenon such as particle
interaction and void filling effects which can effect the cake
layer formation.
4.4 Properties of the Cake Surface under the AFM
Analysis
For pH 9 and 0.03M NaCl, the AFM image analyses are
carried out for 100% W30 and 100% X30 as shown in
Figures 4 (a) and (b). More gaps appear between the
particles in the 100% W30 filtration. This is due to the
higher surface charge in conjunction with the
nonhomogeneity in particle size at this condition. Therefore,
the particles tend to be forced apart from each other making
the cake more porous. The cake was more compact for
100% X30 since the particles have a lower surface charge
compared to the W30 silica and the particle size is more
uniform. This finding was supported by the surface
roughness values shown in Table 5 where 100% X30 has a
smaller surface roughness when compared to the 100% W30
cake surface, which indicates that the cake is less porous
than the 100% W30. Again, these two images explain the
trend of the filtration obtained at different compositions at
pH 9, where the fastest filtration is given by 100% W30 and
the slowest rate is given at 100% X30.
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Fig 4: AFM images on the cake surface yielded from the filtration at pH 9 for a)W30 and b)X30, at pH 6 for c)80%W30 and d)
100%X30 and at pH 4 for e)80%W30 and f)100%W30
Table 5: Surface roughness of the cake obtained at pH 9,6 and 4, 0.03M NaCl.
Sample pH
Surface roughness
qR (nm)
100% W30 9 8.16
100% X30 9 3.37
80% W30 6 12
100% X30 6 8.88
80% W30 4 26.7
100% W30 4 35
Figures 4 (c) and (d) depict the AFM images for the cakes
formed at feed compositions of 80% W30 and 100% X30 at
pH 6. The images show that the cake was flatter for 100%
X30 compared to 80% W30, as the measured surface
roughness at 100% X30 was smaller when compared to 80%
W30 (see Table 5). The particles in the 80% W30, cluster to
each other due to the lower surface charge at pH 6 making
the surface become rougher. As a result the particles deposit
randomly at this condition and build a higher cake layer
compared to 100% X30 and give a maximum flux decline in
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the filtration experiments. Hence, this also promotes the
filling of interstices in the W30 filter cake in the
polydisperse mixture which will increase the cake resistance
(McDonogh et al. 1998). This has been proved by the cake
thickness measurements given in Table 3, where the 80%
W30 shows a greater cake thickness when compared to the
100% X30.
At pH 4 and 0.03M NaCl, the AFM image analysis was
carried out for the filter cake at compositions of 80% W30
and 100% W30 as shown by Figures 4 (e) and (f). Similar to
pH 6, the same composition, 80% W30, has given the
slowest filtration rate at pH 4. However, the cake found at
pH 4 is rougher when compared to the cake formed at pH 6,
where the cake at pH 4 gave a roughness value 55% greater
when compared to pH 6 at the same composition. This
might due to more particles clustering to each other at the
much lower surface potential due to the decrease in pH and
hence surface charge. The attractive force dominates the
total interaction at the lower pH (Bowen and Jenner 1995)
resulting in the particles being closer to each other. The
filtration rate at feed concentrations of 100% W30 and
100% X30 are quite similar at pH 4, but the 100% W30 was
chosen for AFM study since this composition was quite
similar to that which gave the lowest filtration rate (80%
W30). Therefore, the effect of a small change in
composition can be studied. The findings reveal that
addition of a small amount of X30 particles can alter the
particle arrangement in the cake structure causing an
enhanced in cake compactness and resulting the decreases in
surface roughness as depicted in Table 5.
4.5 Direct Comparison between the AFM and SEM
Images
The cake layer obtained from the filtration of 100% X30 at
pH 9 was chosen for direct comparison between the SEM
and AFM images. This was because the X30 filter cake was
smoother so the AFM tip can handle the surface very well.
However, the cake obtained from the 100% W30 solution is
much rougher and the tip has a risk of breaking when it
scans over the surface.
Fig 5: AFM Crosss section topographical image of the a)
60um image of membrane fouled with 100%X30 silica, b)
10 um image of membrane fouled with 100%X30 silica
Figures 5 (a) and (b) show the AFM image for the cross
section of the membrane fouled by X30 particles. Figure 5
(a) shows that membrane was made of finger like macro
voids and nodular structures. Khulbe et al. (2006) reported
the image of the cross section for the hollow fiber
membranes by AFM, and the studies confirm the existence
of finger like macro voids and nodular structures. The AFM
picture in Khulbe et al. 2
but the image is not well defined. The AFM images
presented in this study represent the first time that good
images of the cross sectional area for a fouled membrane
have been obtained, even at higher scan areas in the range of
2 2
. Figure 5 (b) shows the close up
2
.
The nodules surface looks very rough which was due to the
fabrication process in manufacturing to form the air gap
structure (Khulbe et al. 2006).
The surface roughness data for the different areas labelled in
Figure 5 (a) are shown in Table 6 in order to show that the
different composition in all these sections can be quantified
in terms of surface roughness. The cake layer has given the
highest surface roughness when compared to the finger
shaped layer and nodule structure. However, it should be
noted that the surface roughness for the cake in this case was
not the same as the surface roughness from the top view as
this image represents the cross section area. Therefore, the
roughness of the cake formed here was affected by the
breaking process involved in preparing the sample, so the
surface became far rougher when compared to the top view
surface roughness.
Table 6: Surface roughness of various areas of the fouled
membrane
Section Surface roughness qR (nm)
Finger shaped layer 151
Porous layer 105
Cake layer 263
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The image of the cake layer in Figure 5 (a) was not very
clear. Phase imaging, which is a variant of tapping mode
AFM imaging, was employed as this type of imaging can be
used as an enhancement technique to detect variations in
composition and also to provide a clearer observation of fine
features which can be obscured by rough topography.
Figures 6 (a) and (b) show the phase images of Figure 5 (a).
These phase images clearly show the differences in surface
composition which consists of a layer of finger shaped
structures, porous structures (nodule layer) and cake layer as
labelled in Figure 6 (a). The AFM Nanoscape software
application allows the thickness measurement for the cake
layer and porous structure in the AFM images as shown in
Figure 6 (b). The cake thickness areas are labelled as p and
q, and the porous structure thicknesses are labelled as r and
s. All values labelled in Figure 6 (b) are summarized in
Table 7. The average thickness for the cake layer and porous
structure was 6.45 m and 25.34 m respectively.
Fig 6: AFM cross-sect 2
) of the
fouled membrane for 100% X30 at pH 9: a) image with
structures labelled, b) thickness of the cake layer and porous
structure measurement.
Table 7: Measurement of cake layer and porous structure
thickness
Label Area Thickness (µm)
p Cake layer 6.28
q Cake layer 6.63
r Porous layer 25.7
s Porous layer 24.9
In contrast to AFM images, the images from the SEM
analysis are more distinctive for observing the existence of
the different layers shown in Figures 7 (a) and (b). The
average thickness for the cake layer obtained from the SEM
image was 6.39 m . It should be noted that the cake layer
obtained for direct comparison for SEM-AFM analysis was
thicker when compared to the cake measured in Table 2 for
X30 at pH 9. This was because the procedure to obtain the
cake layer was slightly different between these two
experiments.
Fig 7: Cross sectional image for the SEM with the same
sample use in the AFM cross section where ; a) Label
diagram , b) Cake thickness
For direct comparison analysis, the cake was collected after
all the solution was filtered through in order to avoid the
cake layer been washed away from the membrane surface.
As a result, the cake obtained from this analysis is 50 times
thicker when compared to the cake measured in Table 2 for
100% X30. However, the cake was still not as thick as the
amount predicted theoretically. The average thickness for
the porous structure is 27.65 m . A better image of the
porous structure and the finger shaped layer are visible in
the SEM images due to the limitation of the tips in AFM to
reach the area which was deeper than the surrounding area.
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5. CONCLUSION
As a conclusion, the AFM images confirm the current
findings obtained from the SEM regarding the W30 and X30
silica particles. There is not much difference in the thickness
for the cake or porous structures measured using AFM or
SEM. However, the imaging process is much easier with the
SEM compared to the AFM as the surface roughness for the
cross sectional area of the membrane is very rough. This is
due to the limitation of the tip in AFM to reach this area
especially for the finger shaped regions. Meanwhile with
SEM, as the beam can travel through this surface this leads
to this method being more successful for studying the cross
section of the membrane. However, the phase image which
was obtained by AFM also showed the different structures.
Hence, AFM can provide data such as surface roughness,
3D images and z-scale data which is very useful in data
analysis. Nonetheless, sample preparation techniques before
imaging the cross section in AFM and SEM need to be
improved in order to consistently produce high resolution
images of the cross section membranes and filter cakes.
ACKNOWLEDGEMENTS
We would like to thank to University Malaysia Pahang for
funded a scholarship for Nor Hanuni Ramli
NOMENCLATURE
Units
mA Membrane area
2
m
Cb Solution feed concentration m3
m-3
pid Mean diameter of particle i m
ds Mean particle diameter m
vgd Geometric mean diameter m
J Flux
-1
m s
m Mass of the cake layer kg
in Number of particle type i -
Rm Resistance of Membrane m-1
Rc Resistance due to cake layer m-1
t Filtration time s
T Temperature K
V Volume filtered m3
Viscosity of the solvent kg m-1
s-1
c Specific resistance of the deposited mass
m-2
Fractional cake voidage at the membrane
surface -
Zeta potential mV
thickness m
Density kg m-3
g Geometric standard deviation -
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