The problem of the relaxation of a cold package of critical or supercritical fluid in a hotter environment of the same fluid is studied. An asymptotic theory valid in the limit of small values of the parameter ð=ðŸâð , where ðŸâ is the ratio between the characteristic thermal diffusion time and the life time of the droplet and ð the ratio between the fluid densities at the hot and cold regions is developed. Recession laws which are different from the classical ð2 law can be derived from the zeroth order approximation solution in subcritical case [6] as well in critical and supercritical ones. Except for the critical case, additional assumptions on the thermodynamical properties of the gas phase restore the classical ð2 law. A numerical resolution of the problem for a Van der Waals gas in supercritical conditions is performed to check the validity of the results of the asymptotic analysis. It is found that a transition region generally separate the two regions of the fluid in the supercritical conditions. The behavior of this region is numerically analyzed.
This document provides an introduction and table of contents to the book "Introduction to Transport Phenomena - Momentum, Heat and Mass" by Bodh Raj. The book covers momentum transfer, heat transfer, and mass transfer phenomena across four main sections. It is intended as an introductory text for undergraduate students and includes solved examples and problems for each chapter.
1. Mass transfer is the movement of a component from one location to another where the concentration is different. It occurs through molecular diffusion and eddy diffusion.
2. Molecular diffusion is the random movement of molecules due to thermal motion. Eddy diffusion is the random macroscopic fluid motion in turbulent flows.
3. Fick's first law states that the rate of molecular diffusion is proportional to the concentration gradient. The rate of mass transfer stops when concentrations are uniform.
The document discusses various analogies that can be drawn between the transport processes of momentum, heat, and mass. It explains that the basic transport mechanisms are the same and the governing equations are identical in form. Various analogies are presented, including the Reynolds analogy and modifications by Prandtl and von Korman that account for viscous sublayers and buffer layers in turbulent transport.
Thermohaline Convection With Variable Viscosityresearchinventy
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The problem of double diffusive convection with variable viscosity confined between the two horizontal plates is investigated by the linear stability analysis. The transformed governing equations are numerically solved by using the Galerkin method. We have studied both stationary convection and oscillatory convection. The threshold values of Rayleigh number and wave number are computed and presented for various boundary conditions viz. rigid-rigid (í /í ), rigid-free (í /í¹), free-rigid (í¹/í ) and free-free (í¹/í¹) and for different values of physical parameters viz., salinity Rayleigh numberí í , Lewis number L, viscosity ratio c and Prandtl numberíí . For rigid-rigid boundary conditions we have studied the effect of í, í í on the vertical velocity and temperature eigenfunctions at the onset. It is observed that the salinity concentration stabilizes the dynamical system. The occurrence of co-dimension two bifurcation point(í¶íí)is shown for various boundary conditions.
The document discusses transport phenomena and provides definitions and examples of key concepts in vector and tensor analysis used to describe transport phenomena. It defines transport phenomena as dealing with the movement of physical quantities in chemical or mechanical processes. There are three main types of transport: momentum, energy, and mass transport. Vector and tensor quantities like velocity, stress, and strain gradient are used to describe transport phenomena. Tensors have a magnitude and direction(s) and transform under coordinate system rotations. The document provides examples of scalar, vector, and tensor notation and the Kronecker delta, alternating unit tensor, and mathematical operations on vectors like addition, dot product, and cross product.
This document contains 19 multiple choice questions regarding mechanical properties of fluids. The questions cover topics such as pressure, density, buoyancy, and their relationships. Key details assessed include the definitions of fluid, gauge pressure, factors that influence pressure in liquids, and applications of fluid properties such as hydraulic jacks.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document provides an introduction and table of contents to the book "Introduction to Transport Phenomena - Momentum, Heat and Mass" by Bodh Raj. The book covers momentum transfer, heat transfer, and mass transfer phenomena across four main sections. It is intended as an introductory text for undergraduate students and includes solved examples and problems for each chapter.
1. Mass transfer is the movement of a component from one location to another where the concentration is different. It occurs through molecular diffusion and eddy diffusion.
2. Molecular diffusion is the random movement of molecules due to thermal motion. Eddy diffusion is the random macroscopic fluid motion in turbulent flows.
3. Fick's first law states that the rate of molecular diffusion is proportional to the concentration gradient. The rate of mass transfer stops when concentrations are uniform.
The document discusses various analogies that can be drawn between the transport processes of momentum, heat, and mass. It explains that the basic transport mechanisms are the same and the governing equations are identical in form. Various analogies are presented, including the Reynolds analogy and modifications by Prandtl and von Korman that account for viscous sublayers and buffer layers in turbulent transport.
Thermohaline Convection With Variable Viscosityresearchinventy
Â
The problem of double diffusive convection with variable viscosity confined between the two horizontal plates is investigated by the linear stability analysis. The transformed governing equations are numerically solved by using the Galerkin method. We have studied both stationary convection and oscillatory convection. The threshold values of Rayleigh number and wave number are computed and presented for various boundary conditions viz. rigid-rigid (í /í ), rigid-free (í /í¹), free-rigid (í¹/í ) and free-free (í¹/í¹) and for different values of physical parameters viz., salinity Rayleigh numberí í , Lewis number L, viscosity ratio c and Prandtl numberíí . For rigid-rigid boundary conditions we have studied the effect of í, í í on the vertical velocity and temperature eigenfunctions at the onset. It is observed that the salinity concentration stabilizes the dynamical system. The occurrence of co-dimension two bifurcation point(í¶íí)is shown for various boundary conditions.
The document discusses transport phenomena and provides definitions and examples of key concepts in vector and tensor analysis used to describe transport phenomena. It defines transport phenomena as dealing with the movement of physical quantities in chemical or mechanical processes. There are three main types of transport: momentum, energy, and mass transport. Vector and tensor quantities like velocity, stress, and strain gradient are used to describe transport phenomena. Tensors have a magnitude and direction(s) and transform under coordinate system rotations. The document provides examples of scalar, vector, and tensor notation and the Kronecker delta, alternating unit tensor, and mathematical operations on vectors like addition, dot product, and cross product.
This document contains 19 multiple choice questions regarding mechanical properties of fluids. The questions cover topics such as pressure, density, buoyancy, and their relationships. Key details assessed include the definitions of fluid, gauge pressure, factors that influence pressure in liquids, and applications of fluid properties such as hydraulic jacks.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
The document discusses gases and their properties according to the kinetic molecular theory. It defines the key concepts of gases including their state, composition of molecules, and random motion. It also outlines the assumptions of the kinetic molecular theory for ideal gases and describes the variables used in gas laws - temperature, pressure, volume, and moles. Real gases are known to deviate from ideal behavior at high pressures or low temperatures due to intermolecular forces and molecular size.
This document provides information about a fluid mechanics course. It includes the course instructor's contact information and recommended textbooks. It then introduces key concepts in fluid mechanics, defining it as the study of fluids at rest or in motion. It discusses the distinction between solids and fluids, and between gases and liquids. It also outlines several application areas of fluid mechanics in fields like biomechanics, household systems, mechanical engineering, and civil engineering.
Modeling of gas dynamics in a pulse combustion chamber (Kuts)Alex Fridlyand
Â
1) A mathematical model of gas dynamics in a pulse combustion chamber was developed to model the initial drying process. The model considers gas pressure, velocity, and temperature fluctuations over time.
2) The model equations account for gas viscosity and introduce a "second viscosity" term to describe compressions and rarefactions in the pulsating gas flow. This term helps stabilize the computational solution.
3) Numerical solution of the gas dynamics model shows that gas pressure and velocity vary sinusoidally over time, with the velocity exhibiting a phase shift relative to the pressure. The model can provide insights into optimizing pulse combustion chamber design and drying process parameters.
This document discusses simultaneous heat and mass transfer processes. It notes that heat conduction, mass diffusion, and fluid flow obey similar governing equations. While heat and mass transfer are mathematically analogous for gases, they are not as closely coupled for liquids due to lower mass diffusivity. The Chilton-Colburn analogy was developed based on experimental data to relate heat and mass transfer coefficients for liquids, with an exponent of 2/3. Cooling tower design examples demonstrate how heat and mass transfers are coupled in such systems.
Gas-Particulate Models of Flow through Porous StructuresIJERA Editor
Â
A recently developed general model of gas-particulate flow is sub-classified in this work. The model takes into
account both the Darcy resistance and the Forchheimer effects, and is valid for variable particle number density
and flow through variable porosity media. The form of governing equations is discussed when the particle
relaxation time is small.
Effect of Radiation on Mixed Convection Flow of a Non-Newtonian Nan fluid ove...IJMER
Â
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Chemistry involves experimentally studying the physical and chemical properties of substances and measuring them precisely. Measurements have some uncertainty depending on the skill of the person and instrument used. Significant figures refer to the digits that convey the accuracy of a measurement based on the instrument's least count. Chemical quantities and reactions follow various laws including the law of conservation of mass, law of definite proportions, law of multiple proportions, and Gay-Lussac's law of gas volumes in chemical combinations. Dalton's atomic hypothesis provided a theoretical basis for these laws by proposing that elements are made of atoms that combine in fixed ratios to form compounds.
This document provides an overview of key concepts from the kinetic molecular theory as it relates to the behavior and properties of gases. It discusses how gas particles are in constant, random motion and experience no intermolecular forces. The kinetic molecular theory can explain various gas properties like low density, compression/expansion, diffusion, effusion, gas pressure, and Dalton's law of partial pressures. Gas pressure is defined and can be measured using devices like barometers and manometers. Common pressure units are also introduced.
Chap 1(a) molecular-diffusion_in_gas(2)Charice Wan
Â
The document discusses principles of molecular diffusion in gases. It covers topics such as equimolar counter diffusion, diffusion through cross-sectional areas like spheres, and calculating diffusion coefficients. Examples and problems are provided to demonstrate how to calculate flux and diffusion rates in various scenarios, including diffusion between binary gas mixtures and evaporation from surfaces. Methods for estimating gas diffusivity are also presented.
This presentation is made to provide the overall conceptual knowledge on Chilton Colburn Analogy. It includes basis, importance, assumption, advantages, limitations and applications in addition to the derivation. Make It Useful!
The document provides an introduction to fluid dynamics and fluid mechanics. It defines key fluid properties like density, viscosity, pressure and discusses the continuum hypothesis. It also introduces important concepts like the Navier-Stokes equations, Bernoulli's equation, Reynolds number, and divergence. Applications of fluid mechanics in various engineering fields are also highlighted.
Mathematical modelling and analysis of three dimensional darcyIAEME Publication
Â
This document presents a mathematical model and numerical analysis of three-dimensional natural convection in an inclined porous box using the Darcy-Brinkman flow model. Governing equations for mass, momentum and energy are derived in dimensionless form using parameters like Rayleigh number, Darcy number, and aspect ratios. Numerical solutions are obtained for varying parameters like Rayleigh number, Darcy number, and angle of inclination. Results show that average Nusselt number first increases and then decreases with inclination angle, due to a transition from multicellular to unicellular flow patterns. Three-dimensional effects are more pronounced at lower aspect ratios.
Evaporation effects on jetting performanceRobert Cornell
Â
This document discusses evaporation effects on inkjet performance and image quality. It summarizes that as nozzles sit idle, water evaporation causes large localized viscosity variations in the inkjet ejector. This has a negative impact on jetting performance and print quality. The document then goes into detail explaining the multi-physics involved, including heat and mass convection/diffusion at the ink-air interface, and how this affects the transient viscosity fields and ultimately jetting and image quality. Models are used to predict and understand these relationships and tradeoffs between ink formulation, environmental effects, and ejector design.
This document discusses mass transfer and diffusion. It begins by introducing mass transfer and explaining that it occurs due to concentration gradients, with the rate of transfer proportional to the gradient according to Fick's law. It then draws analogies between heat and mass transfer, discussing conduction, convection, and other concepts. The document provides various equations to calculate mass transfer rates and explains concepts like boundary conditions, diffusion coefficients, and steady diffusion through walls. It is intended to help understand the physical mechanisms and analyze problems involving mass transfer and diffusion.
Includes the principles of the KMT and their application to molecular behavior.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
The document describes a project to design, simulate, and test a water rocket. A control volume analysis and flight model from previous research was used to simulate the rocket's performance in MATLAB and predict a maximum height of 55±2 meters. Two test launches were conducted, with heights of 22±5 meters and 43±6 meters, which did not match the predicted height due to non-vertical flight and mass changes not accounted for in the model. Adjusting the model to account for these factors resulted in a predicted height of 51±3 meters, closely matching the higher test result and demonstrating the model's usefulness when assumptions are validated with test conditions.
The document discusses gases and their properties according to the kinetic molecular theory. It defines gases as being composed of particles in constant, random motion that collide elastically. The particles are considered to have negligible volume and no intermolecular forces. It describes the variables used in gas laws - temperature, pressure, volume, and moles - and how they relate to the kinetic molecular theory and behavior of gas particles. It also discusses gas measurement techniques like manometers and the different units used to measure pressure.
Role of Natural and Synthetic Fillers on Erosive Wear Behavior of Basalt -Epo...IJRES Journal
Â
An investigation was made to evaluate the effect of the incorporation of bio-based jatropha oil cake (JOC), Titanium dioxide (TiO2) and Clay on the erosive wear behavior of Basalt-epoxy (BE) hybrid composites. A Vacuum-Assisted Resin Infusion (VARI) technique was employed to obtain a filled and unfilled B-E composites. The effect of different impact velocities (20 and 40 m/s) and angle of impingement from 300 to 900 on the performance of the wear resistance of the composites were measured. The results of erosive wear losses, angle of impingement, and impact velocity and erosion rate of 3% of TiO2 and JOC filled and unfilled B-E composites are analyzed and discussed. The worn surface features of unfilled and filled B-E composites were examined using Scanning Electron Microscopy (SEM).
Power Aware Cluster to Minimize Load In Mobile Ad Hoc NetworksIJRES Journal
Â
Mobile ad hoc networks (MANETs) are popularly known to their mobility and ease of usage. These networks are a set of identical nodes that move freely to communicate among networks and they are represented as a set of clusters. However, their wireless and active natures cause them to be more susceptible to various types of security attacks and transmission energy consumption so that they drop out of the network easily. Now-a-days the major challenge of MANETS is to endow with the assurance to the secure network services and also to provide a nearby balance of load for the cluster-heads. To meet this confront, certificate revocation with load balancing is an important central component to provide security and energy conservation in the network communications. In this paper, we focus on load balancing clustering to widen the lifetime of the cluster-head for a maximum time before allowing it to withdraw so as to distribute the responsibility to other legitimate nodes in the cluster to act as a cluster-head along with the issue of certificate revocation process. For quick, accurate, secure certificate revocation and to conserve energy, we propose the CCRV with Load Balancing Clustering scheme where we can reduce the burden of the cluster along with secure certificate revocation. In particular, to minimize the transmission energy consumption, we use the master slave model to operate the network with longer lifetime and we propose load balancing mechanism to enhance the lifetime of the cluster-head.
A Revisit To Forchheimer Equation Applied In Porous Media FlowIJRES Journal
Â
This document presents an experimental study that revisits the Forchheimer equation for modeling flow through porous media. The study aims to express the coefficients in the Forchheimer equation in terms of measurable media properties. Experiments were conducted using different sizes of coarse materials and glass spheres in a specially designed permeameter. For Reynolds numbers below 10, the results agreed with Darcy's linear law. For higher Reynolds numbers, the inverse of hydraulic gradient varied linearly with velocity, supporting the Forchheimer equation. The coefficients decreased with increasing media size. Equations were proposed relating the coefficients to media properties.
Analysis Of 3C-Sic Double Implanted MOSFET With Gaussian Profile Doping In Th...IJRES Journal
Â
The present work aims at the design of 3C-SiC Double Implanted Metal Oxide Semiconductor Field Effect Transistor (DIMOSFET) with Gaussian doping profile in drift region for high breakdown voltages. By varying the device height âhâ, function constant m and peak concentration ð0, analysis has been done for an optimum profile for high breakdown voltage. With Gaussian profile peak concentration ð0 = 1016 ððâ3 at drain end and m as 1.496 Ã10â2cm, highest breakdown voltage of 6.84kV has been estimated with device height of 200ÎŒm.
The document discusses gases and their properties according to the kinetic molecular theory. It defines the key concepts of gases including their state, composition of molecules, and random motion. It also outlines the assumptions of the kinetic molecular theory for ideal gases and describes the variables used in gas laws - temperature, pressure, volume, and moles. Real gases are known to deviate from ideal behavior at high pressures or low temperatures due to intermolecular forces and molecular size.
This document provides information about a fluid mechanics course. It includes the course instructor's contact information and recommended textbooks. It then introduces key concepts in fluid mechanics, defining it as the study of fluids at rest or in motion. It discusses the distinction between solids and fluids, and between gases and liquids. It also outlines several application areas of fluid mechanics in fields like biomechanics, household systems, mechanical engineering, and civil engineering.
Modeling of gas dynamics in a pulse combustion chamber (Kuts)Alex Fridlyand
Â
1) A mathematical model of gas dynamics in a pulse combustion chamber was developed to model the initial drying process. The model considers gas pressure, velocity, and temperature fluctuations over time.
2) The model equations account for gas viscosity and introduce a "second viscosity" term to describe compressions and rarefactions in the pulsating gas flow. This term helps stabilize the computational solution.
3) Numerical solution of the gas dynamics model shows that gas pressure and velocity vary sinusoidally over time, with the velocity exhibiting a phase shift relative to the pressure. The model can provide insights into optimizing pulse combustion chamber design and drying process parameters.
This document discusses simultaneous heat and mass transfer processes. It notes that heat conduction, mass diffusion, and fluid flow obey similar governing equations. While heat and mass transfer are mathematically analogous for gases, they are not as closely coupled for liquids due to lower mass diffusivity. The Chilton-Colburn analogy was developed based on experimental data to relate heat and mass transfer coefficients for liquids, with an exponent of 2/3. Cooling tower design examples demonstrate how heat and mass transfers are coupled in such systems.
Gas-Particulate Models of Flow through Porous StructuresIJERA Editor
Â
A recently developed general model of gas-particulate flow is sub-classified in this work. The model takes into
account both the Darcy resistance and the Forchheimer effects, and is valid for variable particle number density
and flow through variable porosity media. The form of governing equations is discussed when the particle
relaxation time is small.
Effect of Radiation on Mixed Convection Flow of a Non-Newtonian Nan fluid ove...IJMER
Â
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Chemistry involves experimentally studying the physical and chemical properties of substances and measuring them precisely. Measurements have some uncertainty depending on the skill of the person and instrument used. Significant figures refer to the digits that convey the accuracy of a measurement based on the instrument's least count. Chemical quantities and reactions follow various laws including the law of conservation of mass, law of definite proportions, law of multiple proportions, and Gay-Lussac's law of gas volumes in chemical combinations. Dalton's atomic hypothesis provided a theoretical basis for these laws by proposing that elements are made of atoms that combine in fixed ratios to form compounds.
This document provides an overview of key concepts from the kinetic molecular theory as it relates to the behavior and properties of gases. It discusses how gas particles are in constant, random motion and experience no intermolecular forces. The kinetic molecular theory can explain various gas properties like low density, compression/expansion, diffusion, effusion, gas pressure, and Dalton's law of partial pressures. Gas pressure is defined and can be measured using devices like barometers and manometers. Common pressure units are also introduced.
Chap 1(a) molecular-diffusion_in_gas(2)Charice Wan
Â
The document discusses principles of molecular diffusion in gases. It covers topics such as equimolar counter diffusion, diffusion through cross-sectional areas like spheres, and calculating diffusion coefficients. Examples and problems are provided to demonstrate how to calculate flux and diffusion rates in various scenarios, including diffusion between binary gas mixtures and evaporation from surfaces. Methods for estimating gas diffusivity are also presented.
This presentation is made to provide the overall conceptual knowledge on Chilton Colburn Analogy. It includes basis, importance, assumption, advantages, limitations and applications in addition to the derivation. Make It Useful!
The document provides an introduction to fluid dynamics and fluid mechanics. It defines key fluid properties like density, viscosity, pressure and discusses the continuum hypothesis. It also introduces important concepts like the Navier-Stokes equations, Bernoulli's equation, Reynolds number, and divergence. Applications of fluid mechanics in various engineering fields are also highlighted.
Mathematical modelling and analysis of three dimensional darcyIAEME Publication
Â
This document presents a mathematical model and numerical analysis of three-dimensional natural convection in an inclined porous box using the Darcy-Brinkman flow model. Governing equations for mass, momentum and energy are derived in dimensionless form using parameters like Rayleigh number, Darcy number, and aspect ratios. Numerical solutions are obtained for varying parameters like Rayleigh number, Darcy number, and angle of inclination. Results show that average Nusselt number first increases and then decreases with inclination angle, due to a transition from multicellular to unicellular flow patterns. Three-dimensional effects are more pronounced at lower aspect ratios.
Evaporation effects on jetting performanceRobert Cornell
Â
This document discusses evaporation effects on inkjet performance and image quality. It summarizes that as nozzles sit idle, water evaporation causes large localized viscosity variations in the inkjet ejector. This has a negative impact on jetting performance and print quality. The document then goes into detail explaining the multi-physics involved, including heat and mass convection/diffusion at the ink-air interface, and how this affects the transient viscosity fields and ultimately jetting and image quality. Models are used to predict and understand these relationships and tradeoffs between ink formulation, environmental effects, and ejector design.
This document discusses mass transfer and diffusion. It begins by introducing mass transfer and explaining that it occurs due to concentration gradients, with the rate of transfer proportional to the gradient according to Fick's law. It then draws analogies between heat and mass transfer, discussing conduction, convection, and other concepts. The document provides various equations to calculate mass transfer rates and explains concepts like boundary conditions, diffusion coefficients, and steady diffusion through walls. It is intended to help understand the physical mechanisms and analyze problems involving mass transfer and diffusion.
Includes the principles of the KMT and their application to molecular behavior.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
The document describes a project to design, simulate, and test a water rocket. A control volume analysis and flight model from previous research was used to simulate the rocket's performance in MATLAB and predict a maximum height of 55±2 meters. Two test launches were conducted, with heights of 22±5 meters and 43±6 meters, which did not match the predicted height due to non-vertical flight and mass changes not accounted for in the model. Adjusting the model to account for these factors resulted in a predicted height of 51±3 meters, closely matching the higher test result and demonstrating the model's usefulness when assumptions are validated with test conditions.
The document discusses gases and their properties according to the kinetic molecular theory. It defines gases as being composed of particles in constant, random motion that collide elastically. The particles are considered to have negligible volume and no intermolecular forces. It describes the variables used in gas laws - temperature, pressure, volume, and moles - and how they relate to the kinetic molecular theory and behavior of gas particles. It also discusses gas measurement techniques like manometers and the different units used to measure pressure.
Role of Natural and Synthetic Fillers on Erosive Wear Behavior of Basalt -Epo...IJRES Journal
Â
An investigation was made to evaluate the effect of the incorporation of bio-based jatropha oil cake (JOC), Titanium dioxide (TiO2) and Clay on the erosive wear behavior of Basalt-epoxy (BE) hybrid composites. A Vacuum-Assisted Resin Infusion (VARI) technique was employed to obtain a filled and unfilled B-E composites. The effect of different impact velocities (20 and 40 m/s) and angle of impingement from 300 to 900 on the performance of the wear resistance of the composites were measured. The results of erosive wear losses, angle of impingement, and impact velocity and erosion rate of 3% of TiO2 and JOC filled and unfilled B-E composites are analyzed and discussed. The worn surface features of unfilled and filled B-E composites were examined using Scanning Electron Microscopy (SEM).
Power Aware Cluster to Minimize Load In Mobile Ad Hoc NetworksIJRES Journal
Â
Mobile ad hoc networks (MANETs) are popularly known to their mobility and ease of usage. These networks are a set of identical nodes that move freely to communicate among networks and they are represented as a set of clusters. However, their wireless and active natures cause them to be more susceptible to various types of security attacks and transmission energy consumption so that they drop out of the network easily. Now-a-days the major challenge of MANETS is to endow with the assurance to the secure network services and also to provide a nearby balance of load for the cluster-heads. To meet this confront, certificate revocation with load balancing is an important central component to provide security and energy conservation in the network communications. In this paper, we focus on load balancing clustering to widen the lifetime of the cluster-head for a maximum time before allowing it to withdraw so as to distribute the responsibility to other legitimate nodes in the cluster to act as a cluster-head along with the issue of certificate revocation process. For quick, accurate, secure certificate revocation and to conserve energy, we propose the CCRV with Load Balancing Clustering scheme where we can reduce the burden of the cluster along with secure certificate revocation. In particular, to minimize the transmission energy consumption, we use the master slave model to operate the network with longer lifetime and we propose load balancing mechanism to enhance the lifetime of the cluster-head.
A Revisit To Forchheimer Equation Applied In Porous Media FlowIJRES Journal
Â
This document presents an experimental study that revisits the Forchheimer equation for modeling flow through porous media. The study aims to express the coefficients in the Forchheimer equation in terms of measurable media properties. Experiments were conducted using different sizes of coarse materials and glass spheres in a specially designed permeameter. For Reynolds numbers below 10, the results agreed with Darcy's linear law. For higher Reynolds numbers, the inverse of hydraulic gradient varied linearly with velocity, supporting the Forchheimer equation. The coefficients decreased with increasing media size. Equations were proposed relating the coefficients to media properties.
Analysis Of 3C-Sic Double Implanted MOSFET With Gaussian Profile Doping In Th...IJRES Journal
Â
The present work aims at the design of 3C-SiC Double Implanted Metal Oxide Semiconductor Field Effect Transistor (DIMOSFET) with Gaussian doping profile in drift region for high breakdown voltages. By varying the device height âhâ, function constant m and peak concentration ð0, analysis has been done for an optimum profile for high breakdown voltage. With Gaussian profile peak concentration ð0 = 1016 ððâ3 at drain end and m as 1.496 Ã10â2cm, highest breakdown voltage of 6.84kV has been estimated with device height of 200ÎŒm.
Finite Element Simulation of Serrated Chip Formation in High Speed CuttingIJRES Journal
Â
The description of high speed cutting process with simulation based on finite element method provides huge superiorities compared to analytical and experimental models. This work focused on the study of high speed cutting process with finite element method, using commercial software ABAQUS/Explicit. The chip morphology is predicted, and the stress, strain and temperature in the chip are all simulated vividly when cutting stably. The serrated chip formation is explained by the adiabatic shear theory. The results showed that it is better to use the adiabatic shear theory to explain the formation of serrated chip.
Estimation Of Optimum Dilution In The GMAW Process Using Integrated ANN-SAIJRES Journal
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This document presents a study that aimed to optimize process parameters in gas metal arc welding (GMAW) cladding to achieve optimum dilution. Experiments were conducted using a central composite design to develop mathematical models relating welding current, speed, angle, contact tip distance, and pinch to clad bead geometry responses like width, penetration, reinforcement, and dilution percentage. Artificial neural networks and simulated annealing algorithms were then integrated (ANN-SA) to estimate optimal parameters to minimize dilution. The developed models were checked for adequacy and significance. The study aimed to improve corrosion resistance in carbon steel by depositing a corrosion-resistant stainless steel clad layer with minimum dilution.
A Review of Engineering Geology in TanzaniaIJRES Journal
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This paper briefly summaries the engineering geology importance to the development of Tanzania. Tanzania is situated in geologically active region and hence it is subjected to various earthquake and volcanic related hazards. Other factors such as high annual rainfall, rugged topography and intense weathering when combined with earthquake and volcanic related hazards makes Tanzania an extremely challenging and interesting environment for geological engineers. Several large open pit mining operations such as Geita and Buzwagi and the design of tailing dams have involved considerable input from geological engineers both in terms design and development of necessary infrastructures. The construction and maintenance of roads is an important factor in the growth of Tanzania and both major and minor roads have been affected by slope instability problems. The development of hydroelectric power has also involved a significant input from geological engineers in the design and construction of dams and its related structures.
Quantum-inspired artificial fish swarm algorithm based on the Bloch sphere se...IJRES Journal
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To enhance the performance of the intelligent optimization algorithm, a new model of performing search on the Bloch sphere is proposed. Then, by integrating the model into the artificial fish swarm optimization, we present a quantum-inspired artificial fish swarm optimization algorithm. In proposed method, the fishes are encoded with the qubits described on the Bloch sphere. The vector product theory is adopted to establish the axis of rotation, and the Pauli matrices are used to construct the rotation matrices. The four fish behaviors, such as moving, tracking, capturing, aggregating, are achieved by rotating the current qubit about the rotation axis to the target qubit on the Bloch sphere. The Bloch coordinates of qubit can be obtained by measuring with the Pauli matrices, and the optimization solutions can be presented through the solution space transformation. The highlight advantages of this method are the ability to simultaneously adjust two parameters of a qubit and automatically achieve the best match between two adjustment quantities, which may accelerate the optimization process. The experimental results show that the proposed method obviously outperforms the classical one in convergence speed and achieves better levels for some benchmark functions.
Peripheral Review and Analysis of Internet Network SecurityIJRES Journal
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This paper is on the exploration of Internet Network security. With the advent of the internet, security became a major concern for computer users, organizations and the Military. The internet structure itself allow for many security threats to occur. Knowing the attack methods, the architecture of the internet when modified can reduce the possible attacks that can be sent across the network. The internet can be secured by the means of VPN, IPSec, AntiâMalware Software and scanners, Secure Socket Layer, intrusionâdetection, security management, firewalls and cryptography mechanisms. The essence of this research is to forecast the future of internet network security.
Photoinduced Grafting of Methyl Methacrylate onto Dehydrochlorinated poly (Vi...IJRES Journal
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Polyvinyl chloride (PVC) has been dehydrochlorinated in alkaline medium followed by photo-induced graft copolymerization of methyl methacrylate. The grafting has been achieved using a combination of dimethyl amine and benzoyl peroxide, as radical initiator system. The effects of various parameters such as concentrations of monomer, initiator, substrate, and solvent as well as time of light irradiation on the grafting yield, expressed as grafting percentage and grafting efficiency, have been investigated, and the optimum grafting conditions were determined. The dehydrochlorinated PVC and graft products were characterized using FTIR, TGA, DTA, XRD and SEM and the mechanism of grafting was proposed.
A Mathematical Model for the Hormonal Responses During Neurally Mediated Sync...IJRES Journal
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The purpose of this study is to find a Mathematical model for the participation of central serotonergic activity in neurocardiogenic syncope by comparing cortisol and prolactin plasma levels in patients with positive and negative tilt test by using Multivariate Normal Distribution.
Optimal Data Collection from a Network using Probability Collectives (Swarm B...IJRES Journal
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This paper contains the implementation of the BeeAdhoc algorithm for data routing in mobile Ad Hoc Network (MANet). The algorithm was inspired by the foraging behaviour of honey bees and its implementation mimics this behaviour. The integration was done on Network Simulator version 2 (NS-2.34) where different scenarios were considered in comparison with other existing state-of-the-art routing algorithms that have been implemented in the chosen simulator. The comparison was carried out between DSR, DSDV, AOMDV which are all multipath routing algorithms as the BeeAdhoc; this gave a better insight to the different behaviour of the algorithms on a common application environment. Throughput, end-to-end delay and routing overhead constitute the indices used for the performance evaluation. Experimental results showed the best performance of BeeAdhoc over, DSDV and AOMDV algorithms.
Vehicle Recognition at Night Based on Tail LightDetection Using Image ProcessingIJRES Journal
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Automatic recognition of vehicles in front can be used as a component of systems for forward collisions prevention. When driving in dark conditions, vehicles in front are generally visible by their back lights. Present an algorithm that detects vehicles at night using a camera by searching for tail lights. Develop an image processing systems that can efficiently spot vehicles at different distances and in weather and lightning conditions.
Transparent electronics is the next level of technology that the world requires. It is a technology which helps in producing invisible electronic circuits and optoelectronic devices. Numerous applications can be built upon transparent electronics which would change the style of the world we are living in today. The applications contain consumer electronics such as transparent windows which would sense the trespassing and would send a message to the owner of the house regarding the intruding action of someone, transparent windshields, electronic spectacles similar to Google glass, e-Wear or e-Skin etc. However the materials for such type of technology must be transparent and also possess the conductivity characteristics which are quite contradictory. Transparent conductors are neither 100% optically transparent nor metallically conductive. But some of the compounds have been discovered which possess these two properties to a satisfactory extent. And the research of such materials is still going on. The key performance metrics of transparent thin film transistors would be high device mobility and low temperature fabrication. Generally high device mobility enables fast device operation and low power consumption, which broadens the application area of TTFTs. On the other hand, low temperature fabrication is essential for transparent devices made on flexible substrates which would enable novel applications. Low temperature fabrication also lowers the fabrication expense significantly. Despite the above mentioned success, the reported mobility values are still low compared to those of non-transparent devices indicating further room for improvement.
Network on Chip Architecture and Routing Techniques: A surveyIJRES Journal
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This document summarizes research on Network on Chip (NOC) architecture and routing techniques. It discusses NOC topology options including mesh, torus, ring and irregular networks. It also reviews router architecture, switching techniques, virtual channels, buffering, error correction, quality of service implementations, and routing algorithms. Specific NOC implementations discussed include QNOC, Ethereal NOC, and SPIN NOC. The document provides an overview of research on improving performance and efficiency in NOC design.
A Simple Control Strategy for Boost Converter Based Wind and Solar Hybrid Ene...IJRES Journal
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This paper deals about the improvement of output from hybrid (Wind and PV) system through the maximum power point technique (MPPT). Though various power tracking techniques are available, Constant Voltage method is simple and effective way to track the maximum power. In this method output voltage is compared with the maximum voltage and based on the comparison gate signal is generated to the boost converter switch. Two boost converters are used individually for PV and Wind system. The whole system is modeled by using the Matlab/Simulink Model.
Role Of Private Sector Banks In Financial Inclusion: A Case Study On West-BengalIJRES Journal
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The banking industry has shown tremendous growth in volume and complexity during the last few decades, the main concern is that the banks have not been able to reach and bring vast segment of the society into the fold of basic banking sector. Financial inclusion, of late has become one of the major attentions in academic research, public policy, seminars in view of its important role in aiding economic development of the resource poor developing economies. RBI has also taken up different measures to improve the financial inclusiveness of the economy of the country. Rangarajan Committee (2008) on financial inclusion stated that âFinancial inclusion may be defined as the process of ensuring access to financial services and timely and adequate credit where needed by vulnerable groups such as weaker sections and low income groups at an affordable costâ. West-Bengal is one of the most dispersed state in terms of financial inclusion, where only North 24 Parganas and Kolkata showed high levels of inclusiveness (RBI Working Papers). This paper puts emphasis on the present scenario of financial inclusion in the state and outreach of private sector banks (member of SLBC, West-Bengal) in reaching out the different excluded section of the society.
Operational Research and Organizational SystemIJRES Journal
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Organizational systems, as well as specific integration of social and technical systems are extremely important for the development of human society. The most part, the problems of managing these systems are reduced to operations research - a generic term for activities that define the processes involved in the functions of organizational systems, and hence the term operations research. Field of study operations research as a scientific discipline, the organizational processes and activities that are being carried out and an important determinant of the intention to find the best decisions in managing the operations undertaken to achieve the set goals of the system. The generality of operations research is reflected in the fact that apply to all types of organizational systems - commercial, industrial, agricultural, military, medical, educational, government, and the like. Users of operations research decision makers - managers, whose task is to efficiently and effectively manage organizational systems. In this paper we consider operational research and conceptual foundations that enable its effective use in solving the problem of organizational systems.
Design and performance of Four-Stage Adsorption SystemIJRES Journal
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A design of four-stage adsorption system was proposed to utilize very low temperature waste heat or solar heat. A simulation model for the proposed cycle was developed to analyse the influence of cycle time and driving heat source temperature on the performance of system identifying the specific cooling power (SCP) and coefficient of performance (COP). It was found that the proposed cycle could be driven by waste heat temperature as low as 35oC with the coolant at 30oC. Both SCP and COP of the proposed system is very low at lower heat source temperature, which can be improved through optimization of cycle time with other design parameters.
Mathematical modelling and analysis of three dimensional darcyIAEME Publication
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This document presents a mathematical model and numerical analysis of three-dimensional natural convection in an inclined porous box using the Darcy-Brinkman flow model. Governing equations for mass, momentum and energy are derived in dimensionless form using parameters like Rayleigh number, Darcy number, and Prandtl number. Numerical solutions are obtained for varying Rayleigh number, aspect ratios, Darcy number and angle of inclination. Results show average Nusselt number increases with Rayleigh number and angle of inclination up to a critical angle, then decreases as flow transitions from multicellular to unicellular circulation. Three-dimensional effects are more pronounced at lower aspect ratios.
This document provides a review of turbulent combustion modeling closures for large eddy simulations (LES), with a focus on models applicable to propulsion applications. It identifies three classes of models that can provide broad-based modeling: flamelet-library/presumed PDF models, linear eddy based (LEM) models, and transported PDF or filtered density function (FDF) based models. The document discusses the fundamental physical assumptions of these models, particularly regarding the presumed size of the turbulent scalar manifold. It also provides novel results from direct numerical simulations testing some assumptions using flames with detailed and reduced chemistry models.
Asphaltic Material in the Context of Generalized Porothermoelasticity ijsc
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In this work, a mathematical model of generalized porothermoelasticity with one relaxation time for poroelastic half-space saturated with fluid will be constructed in the context of Youssef model (2007). We will obtain the general solution in the Laplace transform domain and apply it in a certain asphalt material which is thermally shocked on its bounding plane. The inversion of the Laplace transform will be obtained numerically and the numerical values of the temperature, stresses, strains and displacements will be illustrated graphically for the solid and the liquid.
This document discusses the development and history of the SPRAY Lagrangian dispersion model code over several decades. It began in the 1980s as a collaboration between researchers in France and Italy to develop a particle-based Lagrangian model. The code was further developed in the 1990s by additional researchers in Italy. It has been used to model dispersion for applications like predicting pollutant concentrations. Key publications discussing updates to the model, like adding chemical reactions and testing against experimental data, are also summarized.
1) The document analytically solves the nonisothermal Buckley-Leverett problem for two-phase immiscible flow in porous media including a tracer component and temperature effects.
2) Mass balances for the fluids and tracer and a convective heat balance equation are formulated and solved using the method of characteristics.
3) The solutions can be used to analyze pressure transients, interpret formation testing, calculate temperature front propagation during waterflooding, and benchmark simulators.
This document discusses hydrothermal waves observed during the evaporation of sessile droplets. Key points include:
- Hydrothermal waves have been observed during the evaporation of methanol, ethanol, and FC-72 droplets using infrared thermography. These waves have been interpreted as surface oscillatory instabilities.
- Additional experiments are presented that support the original findings and interpretation. The data suggest the presence of traveling waves resulting from a Marangoni instability at the liquid-gas interface.
- A theoretical 3D stability analysis in spherical coordinates is proposed to better understand the phenomenon. This would define new scaling factors and dimensionless numbers accounting for substrate thermal diffusivity and evaporation rate.
Porous media has two specifications: First its dissipation area is greater than the conventional fins that enhance heat convection. Second the irregular motion of the fluid flow around the individual beads mixes the fluid more effectively. Nanofluids are mixtures of base fluid with a very small amount of nanoparticles having dimensions from 1 to 100 nm, with very high thermal conductivities, so it would be the best convection heat transfer by using porous media and nanofluids. Thus studies need to be conducted involving nanofluids in porous media. For that, the purpose of this article is to summarize the published subjects respect to the enhancement of convective heat transfer using porous media and nanofluids and identifies opportunities for future research.
Thermodynamic systems, boundaries, and states are introduced.
1) A thermodynamic system is a quantity of matter or a region of space distinguished from its surroundings. It is enclosed by a real or imaginary boundary.
2) Systems are classified as closed, open, or isolated depending on whether mass and/or energy can cross their boundaries.
3) The thermodynamic state of a system is specified by its thermodynamic variables like pressure, volume, and temperature. Variables are either intensive (invariant to system size) or extensive (dependent on system size).
This document summarizes key concepts from Chapter 3 of the source text. It begins by deriving a closed system of averaged hydrodynamic equations to describe turbulent flows in multicomponent media. These equations account for factors like compressibility, heat and mass transfer, and chemical reactions. The document then discusses choosing an appropriate averaging operator for the equations. It argues that using weighted-mean averaging simplified the form and analysis of the equations for compressible, variable density media like those found in astrophysics. This approach defines weighted means for some fluctuating quantities based on the local density. The document aims to establish a general phenomenological theory of turbulent transport in multicomponent mixtures at the first-order closure level.
Mekanika Fluida 1 P2. Oke.pdf, Presentasi kuliah pertemuan 2 untuk mata kulia...ujiburrahman2
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The document discusses properties of fluids including density, specific gravity, vapor pressure, cavitation, compressibility, viscosity, and speed of sound. Some key points:
- Density is mass per unit volume and specific gravity is the ratio of a substance's density to that of water. Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid form.
- Cavitation can occur when pressure drops below vapor pressure, causing vapor bubbles to form and implode violently.
- Compressibility refers to change in volume or density with pressure change. Viscosity is a measure of a fluid's internal resistance to motion.
- Newtonian fluids have viscosity that is independent of stress or
This document summarizes research on oblique shock waves that appear in supersonic carbon dioxide two-phase flow, as occurs in ejector refrigeration cycles. It presents:
1) Theoretical analyses showing that two types of oblique shock waves can occur - weak shocks where flow remains supersonic, and strong shocks with large pressure recovery and subsonic flow.
2) An experiment using a carbon dioxide two-phase flow channel to observe these shock waves.
3) Equations governing compressible two-phase flow and the conditions under which strong and weak oblique shock waves form, to compare with experimental results.
STEADY FLOW OF A VISCOUS FLUID THROUGH A SATURATED POROUS MEDIUM AT A CONSTAN...Journal For Research
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In this paper the Steady flow of a viscous fluid through a porous medium over a fixed horizontal, impermeable and thermally insulated bottom. The flow through the porous medium satisfies the general momentum and energy equations are obtained when the temperature on the fixed bottom and on free surface prescibed. By using Galerkin Method, the expression for Velocity and Drag force are obtained. The Galerkin Method endowed with distinct features that account for its superiority over competing methods. The effect of different parameters on Velocity and Drag force are discussed with the help of graphs.
International Journal of Engineering Research and DevelopmentIJERD Editor
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This document presents a statistical study of the helix-coil transition in agarose. It summarizes two statistical models used to describe the transition: an independent-residue model where each unit can be helical or coil, and a two-state model where the entire chain is either helical or coil. Experimental results on agarose are shown measuring the equilibrium constant and helical fraction as temperature varies. The helical fraction decreases with increasing temperature and increasing chain length. Solvent composition, like DMSO, is also found to affect the helix-coil transition temperature in agarose.
Effect of Geometry on Variation of Heat Flux and Drag for Launch Vehicle -- Z...Abhishek Jain
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Above Research Paper can be downloaded from www.zeusnumerix.com
The research paper aims at studying the variation of the geometry of the launch vehicle nose and its effect on heat flux. CFDExpert software is first validated on NASA's hyperballistic model and then used on proposed geometries. Various nose radius and blending shapes are studied for effect on drag and heat flux. Cone ogive shape is found to decrease heat flux with an insignificant increase in drag. Authors Abhishek Jain (Zeus Numerix), Rohan Kedar and Prof V Kalamkar (SPCOE).
[Harry edmar]hydrodynamics concepts and experimentsEnrique Buenaonda
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This chapter develops a coupled fluid-structure model to simulate the interaction between water flow and a flexible fishing net. The model combines a porous media fluid model and a lumped-mass mechanical model. The porous media fluid model uses the Navier-Stokes equations to simulate flow around a rigid net, while the lumped-mass model simulates net deformation. An iterative scheme is used to solve for the steady fluid-net interaction. The model aims to better understand hydrodynamic forces on nets and flow patterns, which has significance for net cage and aquaculture design.
This document presents a methodology for numerically predicting Nusselt number equations for stirred tanks with helical coils using computational fluid dynamics (CFD). The approach uses a validated CFD model to obtain heat transfer coefficients, which has advantages over experimental methods by allowing testing of different configurations without physical experiments. A literature review covers previous experimental and numerical studies on heat transfer in stirred tanks. Key factors in CFD simulations like mesh refinement, discretization schemes, turbulence models, and approaches to model impeller-baffle interaction are discussed. The methodology is illustrated by comparing a generated Nusselt number correlation to experimental data with an average 10.7% deviation.
Heat transefer of a dusty fluid over a stretching sheet with internal heat ge...eSAT Journals
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Abstract This paper pertains to investigate the heat transfer characteristics of two dimensional two phase flow in a porous medium over a stretching sheet with internal heat generation. The novelty of the present study is to consider the permeability parameter, space and temperature dependent internal heat generation along with various parameters like Froud number ,heat source/sink parameter, Grashof number, Prandtl number, Eckert number, Volume fraction, fluid interaction parameter etc. The method of solution involves similarity transformation which reduces the partial differential equations into non linear ordinary differential equations. These non linear ordinary differential equations have been solved by applying Runge-Kutta 4-th order method with help of shooting technique. The temperature profiles for different values of flow parameters are presented in figures. It is observed from all the figures that the boundary conditions are satisfied asymptotically in all the cases which supporting the accuracy of the numerical results. All the figures shows that increasing values of any parameter increase the thermal boundary layer except the prandtl number and permeability parameter. AMS classification 76T10, 76T15 Keywords: Heat source/sink, Volume fraction, Fluid â particle interaction parameter, Dusty fluid, Boundary layer flow, Stretching sheet, Eckert number, Grashof number, Prandtle number, Shooting techniques, Froud number, permeability parameter.
Similar to Supercritical Evaporation of a Drop (20)
Exploratory study on the use of crushed cockle shell as partial sand replacem...IJRES Journal
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The increasing demand for natural river sand supply for the use in construction industry along
with the issue of environmental problem posed by the dumping of cockle shell, a by-product from cockle
business have initiated research towards producing a more environmental friendly concrete. This research
explores the potential use of cockle shell as partial sand replacement in concrete production. Cockle shell used
in this experimental work were crushed to smaller size almost similar to sand before mixed in concrete. A total
of six concrete mixtures were prepared with varying the percentages of cockle shell viz. 0%, 5%, 10%, 15%,
20% and 25%. All the specimens were subjected to continuous water curing. The compressive strength test was
conducted at 28 days in accordance to BS EN 12390. Finding shows that integration of suitable content of
crushed cockle shell of 10% as partial sand replacement able to enhance the compressive strength of concrete.
Adopting crushed cockle shell as partial sand replacement in concrete would reduce natural river sand
consumption as well as reducing the amount of cockle shell disposed as waste.
Congenital Malaria: Correlation of Umbilical Cord Plasmodium falciparum Paras...IJRES Journal
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The vertical (trans-placental) transmission of the parasite Plasmodium falciparum from
pregnant mother to fetus during gestational period was investigated in a clinical research involving 43 full term
pregnant women in selected Hospitals in Jimeta Yola, Adamawa State Nigeria. During the observational study,
parasitemia was determined by light microscopic examination of umbilical and maternal peripheral blood film
for the presence of the trophozoites of Plasmodium falciparum. Correlational analysis was then carried on the
result obtained at p<0.05.><0.05) was established between maternal peripheral blood and umbilical cord
blood parasitemia with Pearsonâs correlation coefficient of 0.762. Thus, in a malaria endemic area like Yola,
Adamawa State, Nigeria, with a stable transmission of parasite, there is a high probability of vertical
transmission of Plasmodium falciparum parasite from mother to fetus during gestation that can be followed by
the presentation of the symptoms of malaria by the newborn and other malaria related complications. Families
are advised to consistently sleep under appropriately treated insecticide mosquito net to avoid mosquito bite and
subsequent infestation.
Review: Nonlinear Techniques for Analysis of Heart Rate VariabilityIJRES Journal
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Heart rate variability (HRV) is a measure of the balance between sympathetic mediators of heart
rate that is the effect of epinephrine and norepinephrine released from sympathetic nerve fibres acting on the
sino-atrial and atrio-ventricular nodes which increase the rate of cardiac contraction and facilitate conduction at
the atrio-ventricular node and parasympathetic mediators of heart rate that is the influence of acetylcholine
released by the parasympathetic nerve fibres acting on the sino-atrial and atrio-ventricular nodes leading to a
decrease in the heart rate and a slowing of conduction at the atrio-ventricular node. Sympathetic mediators
appear to exert their influence over longer time periods and are reflected in the low frequency power(LFP) of
the HRV spectrum (between 0.04Hz and 0.15 Hz).Vagal mediators exert their influence more quickly on the
heart and principally affect the high frequency power (HFP) of the HRV spectrum (between 0.15Hz and 0.4
Hz). Thus at any point in time the LFP:HFP ratio is a proxy for the sympatho- vagal balance. Thus HRV is a
valuable tool to investigate the sympathetic and parasympathetic function of the autonomic nervous system.
Study of HRV enhance our understanding of physiological phenomenon, the actions of medications and disease
mechanisms but large scale prospective studies are needed to determine the sensitivity, specificity and predictive
values of heart rate variability regarding death or morbidity in cardiac and non-cardiac patients. This paper
presents the linear and nonlinear to analysis the HRV.
Dynamic Modeling for Gas Phase Propylene Copolymerization in a Fluidized Bed ...IJRES Journal
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The document presents a dynamic two-phase model for a fluidized bed reactor used to produce polypropylene. The model divides the reactor into an emulsion phase and bubble phase, with reaction assumed to occur in both phases. Simulation results show the temperature profile is lower than previous single-phase models due to considering both phases. Approximately 13% of the produced polymer comes from the bubble phase, demonstrating the importance of accounting for both phases.
Study and evaluation for different types of Sudanese crude oil propertiesIJRES Journal
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Sudanese crude oil is regarded as one of the sweet types of crude in the world, Sulphur containing
compounds are un desirable in petroleum because they de activate the catalyst during the refining processes and
are the main source of acid rains and environmental pollution.(Mark Cullen 2001),Since it contains considerable
amount of salts and acids, it negatively impact the production facilities and transportation lines with corrosive
materials. However it suffers other problems in flow properties represented by the high viscosity and high
percentage of wax. Samples were collected after the initial and final treatment at CPF, and tested for
physical and chemical properties.wax content is in the range 23-31 weight % while asphalting content is about
0.1 weight% . Resin content is 13-7 weight % and deposits are 0.01 weight%. The carbon number distribution in
the crude is in the range 7-35 carbon atoms. The pour point vary between 39°C-42°C and the boiling point is in
the range 70 °C - 533 °C.
A Short Report on Different Wavelets and Their StructuresIJRES Journal
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This article consists of basics of wavelet analysis required for understanding of and use of wavelet
theory. In this article we briefly discuss about HAAR wavelet transform their space and structures.
A Case Study on Academic Services Application Using Agile Methodology for Mob...IJRES Journal
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Recently, Mobile Cloud Computing reveals many modern development areas in the Information
Technology industry. Several software engineering frameworks and methodologies have been developed to
provide solutions for deploying cloud computing resources on mobile application development. Agile
methodology is one of the most commonly used methodologies in the field. This paper presents the MCCAS a
Web and Mobile application that provide feature for the Palestinian higher education/academic institutions. An
Agile methodology was used in the development of the MCCAS but in parallel with emphasis on Cloud
computing resources deployment. Also many related issues is discussed such as how software engineering
modern methodologies (advances) influenced the development process.
Wear Analysis on Cylindrical Cam with Flexible RodIJRES Journal
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Firstly, the kinetic equation of spatial cylindrical cam with flexible rod has been established. Then, an
accurate cylindrical cam mechanism model has been established based on the spatial modeling software
Solidworks. The dynamic effect of flexible rod on mechanical system was studied in detail based on the
mechanical system dynamics analytical software Adams, and Archard wear model is used to predict the wear of
the cam. We used Ansys to create finite element model of the cam link, extracted the first five order mode to
export into Adams. The simulation results show that the dynamic characteristics of spatial cylindrical cam
mechanical system with flexible rod is closed to ideal mechanism. During the cam rotate one cycle, the collision
in the linkage with a clearance occurs in some special location, others still keep a continuous contact, and the
prediction of wear loss is smaller than rigid body.
DDOS Attacks-A Stealthy Way of Implementation and DetectionIJRES Journal
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Cloud Computing is a new paradigm provides various host service [paas, saas, Iaas over the internet.
According to a self-service,on-demand and pay as you use business model,the customers will obtain the cloud
resources and services.It is a virtual shared service.Cloud Computing has three basic abstraction layers System
layer(Virtual Machine abstraction of a server),Platform layer(A virtualized operating system, database and
webserver of a server and Application layer(It includes Web Applications).Denial of Service attack is an attempt
to make a machine or network resource unavailable to the intended user. In DOS a user or organization is
deprived of the services of a resource they would normally expect to have.A Successful DOS attack is a highly
noticeable event impacting the entire online user base.DOS attack is found by First Mathematical Metrical
Method (Rate Controlling,Timing Window,Worst Case and Pattern Matching)DOS attack not only affect the
Quality of the service and also affect the performance of the server. DDOS attacks are launched from Botnet-A
large Cluster of Connected device(cellphone,pc or router) infected with malware that allow remote control by an
attacker. Intruder using SIPDAS in DDOS to perform attack.SIPDAS attack strategies are detected using Heap
Space Monitoring Algorithm.
An improved fading Kalman filter in the application of BDS dynamic positioningIJRES Journal
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Aiming at the poor dynamic performance and low navigation precision of traditional fading
Kalman filter in BDS dynamic positioning, an improved fading Kalman filter based on fading factor vector is
proposed. The fading factor is extended to a fading factor vector, and each element of the vector corresponds to
each state component. Based on the difference between the actual observed quantity and the predicted one, the
value of the vector is changed automatically. The memory length of different channel is changed in real time
according to the dynamic property of the corresponding state component. The actual observation data of BDS is
used to test the algorithm. The experimental results show that compared with the traditional fading Kalman filter
and the method of the third references, the positioning precision of the algorithm is improved by 46.3% and
23.6% respectively.
Positioning Error Analysis and Compensation of Differential Precision WorkbenchIJRES Journal
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The document analyzes positioning errors in differential precision workbenches and proposes a compensation method. It discusses sources of error in workbench transmission systems and guides. Through theoretical analysis and experimentation, it is shown that positioning errors increase with travel distance due to factors like guideway errors. A method is developed to sample positioning at multiple points, compare values to identify errors, and implement reverse error correction through motion control cards. This allows positioning accuracy better than 15 micrometers over 150mm of travel to be achieved. The compensation method can improve precision for a range of machine tool designs.
Status of Heavy metal pollution in Mithi river: Then and NowIJRES Journal
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The Mithi River runs through the heart of suburban Mumbai. Its path of flow has been severely
damaged due to industrialization and urbanization. The quality of water has been deteriorating ever since. The
Municipal and industrial effluents are discharged in unchecked amounts. The municipal discharge comprises
untreated domestic and sewage wastes whereas the industries are majorly discharge chemicals and other toxic
effluents which are responsible in increasing the metal load of the river. In the current study, the water is
analysed for heavy metals- Copper, Cadmium, Chromium, Lead and Nickel. It also includes a brief
understanding on the fluctuations that have occurred in the heavy metal pollution, through the compilation of
studies carried out in the area previously.
The Low-Temperature Radiant Floor Heating System Design and Experimental Stud...IJRES Journal
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In order to analyze the temperature distribution of the low-temperature radiant floor heating system
that uses the condensing wall-hung boiler as the heat source, the heating system is designed according to a typical
house facing south in Shanghai. The experiments are carried out to study the effects of the supply water
temperature on the thermal comfort of the system. Eventually, the supply water temperature that makes people in
the room feel more comfortable is obtained. The result shows that in the condition of that the outside temperature
is 8~15â and the relative humidity is 30~70%RH, the temperature distribution in the room is from high to low
when the height is from bottom to top. The floor surface temperature is highest, but its uniformity is very poor.
When the heating system reaches the steady state, the air temperature of the room is uniform. When the supply
water temperature is 63â The room is relatively comfortable at the above experimental condition.
Experimental study on critical closing pressure of mudstone fractured reservoirsIJRES Journal
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This study examines the critical closing pressure of fractures in mudstone reservoir cores from the Daqing oilfield in China. Laboratory experiments subjected fractured and unfractured mudstone cores to increasing external pressures while measuring permeability. The critical closing pressure is defined as the pressure when fractured core permeability matches unfractured permeability, indicating fracture closure. Results show fractured cores have higher permeability than unfractured cores due to fractures. Permeability generally decreases exponentially with increasing pressure. By calculating sensitivity equations relating permeability and production pressure difference, the study estimates critical closing pressures under reservoir conditions are lower than values from external pressure experiments. The study provides guidance but notes limitations in fully simulating complex in-situ stress conditions.
Correlation Analysis of Tool Wear and Cutting Sound SignalIJRES Journal
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With the classic signal analysis and processing method, the cutting of the audio signal in time
domain and frequency domain analysis. We reached the following conclusions: in the time domain analysis,
cutting audio signals mean and the variance associated with tool wear state change occurred did not change
significantly, and tool wear is not high degree of correlation, and the mean-square value of the audio signal
changes in the size and tool wear the state has a good relationship.
Reduce Resources for Privacy in Mobile Cloud Computing Using Blowfish and DSA...IJRES Journal
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Mobile cloud computing in light of the increasing popularity among users of mobile smart
technology which is the next indispensable that enables users to take advantage of the storage cloud computing
services. However, mobile cloud computing, the migration of information on the cloud is reliable their privacy
and security issues. Moreover, mobile cloud computing has limitations in resources such as power energy,
processor, Memory and storage. In this paper, we propose a solution to the problem of privacy with saving and
reducing resources power energy, processor and Memory. This is done through data encryption in the mobile
cloud computing by symmetric algorithm and sent to the private cloud and then the data is encrypted again and
sent to the public cloud through Asymmetric algorithm. The experimental results showed after a comparison
between encryption algorithms less time and less time to decryption are as follows: Blowfish algorithm for
symmetric and the DSA algorithm for Asymmetric. The analysis results showed a significant improvement in
reducing the resources in the period of time and power energy consumption and processor.
Resistance of Dryland Rice to Stem Borer (Scirpophaga incertulas Wlk.) Using ...IJRES Journal
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Rice stem borer is one of the important pests that attack plants so as to reduce production. One way
to control pests is to use organic fertilizers that make the plant stronger and healthier. This study was conducted
to determine the effects of organic fertilizers with various doses without the use of pesticides in controlling stem
borer, Scirpophaga incertulas. Methods using split-split plot design which consists of two levels of the whole
plot factor (solid and liquid organic fertilizers), two levels of the subplot factor (conventional and industry,
Tiens and Mitraflora), and four levels of the sub-subplot factor of conventional and industry (5, 10, 15, 20
tonnes/ha), and one level of the sub-subplot factor of Tiens and Mitraflora (each 2 ml/l). Based on the results
Statistical analysis there were no significant differences among treatments and this shows that the use of organic
fertilizers that only a dose of 5 tonnes/ha is sufficient available nutrients that make plants more robust and
resistant to control stem borer, besides that can reduce production costs and friendly to the environment when
compared with using inorganic fertilizers.
A novel high-precision curvature-compensated CMOS bandgap reference without u...IJRES Journal
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A novel high-precision curvature-compensated bandgap reference (BGR) without using op-amp
is presented in this paper. It is based on second-order curvature correction principle, which is a weighted sum of
two voltage curves which have opposite curvature characteristic. One voltage curve is achieved by first-order
curvature-compensated bandgap reference (FCBGR) without using op-amp and the other found by using W
function is achieved by utilizing a positive temperature coefficient (TC) exponential current and a linear
negative TC current to flow a linear resistor. The exponential current is gained by using anegative TC voltage to
control a MOSFET in sub-threshold region. In the temperature ranging from -40â to 125â, experimental
results implemented with SMIC 0.18ÎŒm CMOS process demonstrate that the presented BGR can achieve a TC
as low as 2.2 ppm/â and power-supply rejection ratio(PSRR)is -69 dB without any filtering capacitor at 2.0 V.
While the range of the supply voltage is from 1.7 to 3.0 V, the output voltage line regulation is about1 mV/ V
and the maximum TC is 3.4 ppm/â.
Structural aspect on carbon dioxide capture in nanotubesIJRES Journal
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In this work we reported the carbon dioxide adsorption (CO2) in six different nanostructures in order
to investigate the capturing capacity of the materials at nanoscale. Here we have considered the three different
nanotubes including zinc oxide nanotube (ZnONT), silicon carbide nanotube (SiCNT) and single walled carbon
nanotube (SWCNT). Three different chiralities such as zigzag (9,0), armchair (5,5) and chiral (6,4) having
approximately same diameter are analyzed. The adsorption binding energy values under various cases are
estimated with density functional theory (DFT). We observed CO2 molecule chemisorbed on ZnONT and
SiCNTâs whereas the physisorption is predominant in CNT. To investigate the structural aspect, the tubes with
defects are studied and compared with defect free tubes. We have also analyzed the electrical properties of tubes
from HOMO, LUMO energies. Our results reveal the defected structure enhance the CO2 capture and is
predicted to be a potential candidate for environmental applications.
Thesummaryabout fuzzy control parameters selected based on brake driver inten...IJRES Journal
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In this paper, the brake driving intention identification parameters based on the fuzzy control are
summarized and analyzed, the necessary parameters based on the fuzzy control of the brake driving intention
recognition are found out, and I pointed out the commonly corrupt parameters, and through the relevant
parameters , I establish the corresponding driving intention model.
BIRDS DIVERSITY OF SOOTEA BISWANATH ASSAM.ppt.pptxgoluk9330
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Ahota Beel, nestled in Sootea Biswanath Assam , is celebrated for its extraordinary diversity of bird species. This wetland sanctuary supports a myriad of avian residents and migrants alike. Visitors can admire the elegant flights of migratory species such as the Northern Pintail and Eurasian Wigeon, alongside resident birds including the Asian Openbill and Pheasant-tailed Jacana. With its tranquil scenery and varied habitats, Ahota Beel offers a perfect haven for birdwatchers to appreciate and study the vibrant birdlife that thrives in this natural refuge.
The shorelines of Titanâs hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titanâs seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titanâs seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ⌠106Mâ black hole (BH) that is currently in the process of âturning onâ. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1âW2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ⌠3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ⌠106Mâ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: activeâ accretion, accretion discsâ galaxies: individual: SDSS J133519.91+072807.4
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the RâI spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional âdarkâ gravitational force describing the âelasticâ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newtonâs constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional âdark gravity forceâ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...PsychoTech Services
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A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
2. Supercritical Evaporation of a Drop
www.ijres.org 42 | Page
the subcritical evaporation: the initial density inhomogeneity due to the pocket can be assimilated to a droplet
when the surrounding atmosphere is hotter [7, 8, 9].
The assumption of quasi-steadiness of the gaseous environment surrounding the droplet is essential for the
establishment of the ð2
law. The validity of this hypothesis which seems to be limited to the case of low
pressure where the density of the liquid is at least three times higher than the density of the gas [13] persists in
the critical and supercritical evaporation at very high pressures when the densities of the cold and hot fluids are
comparable [10, 11].
The rest of the paper is organized as follows. In Section 2, using the formalism developed in [6], we show
that the ð2
law remains valid under certain conditions in the supercritical evaporation while it could not be
established for the critical evaporation. In section 3, we study numerically the behavior of a supercritical fluid
pocket in a hotter environment of the same fluid. Particular emphasis was placed on the description and analysis
of the transition zone.
II. RECESSION LAW IN CRITICAL AND SUPERCRITICAL EVAPORATION
1. Position of the problem
A pocket of critical or supercritical fluid at a uniform temperature is suddenly introduced into a hotter
infinite atmosphere of the same fluid initially at rest. The physical model adopted assumes the spherical
symmetry of the pocket and the flow, the absence of viscosity and gravity and a uniform pressure in the flow
domain. We denote by ðâ² the distance to the center of the pocket and ð â² its radius. A law of state which will be
specified in section 3 gives the pressure ðâ² in the flow as a function of the density ðâ² and temperature ðâ² ; ð£â² is
the velocity of the flow. The radius, the density and temperature of the cold pocket at the initial time are
respectively ð â²
0 = ð â²ðð , ðâ²
0 = ðâ²ðð
and ðâ²
0 = ðâ²ðð . The conservation equations of the model are
written in a reference frame tied to the border of the pocket and we introduce the variable ð¥â²
= ðâ²
â ð â²
.
We retain as in [6] two characteristic times in the description of the relaxation: the characteristic time of
thermal diffusion ð¡â² ððð and the pocket life time ð¡â² ððð . To take into account the gradient of density in the
environment, we use two characteristic densities: ðâ²ð
in the pocket and ðâ²â
in the surrounding gas. We introduce
the dimensionless numbers ðŸâ =
ð¡â² ððð
ð¡â² ððð
, â =
ðâ²â
ðâ²ð
, ðð =
ð¶ðâ²â ð â²ðð ðâ²â
ðâ²â ð¡â² ððð
and the following dimensionless variables :
ð¡ =
ð¡â²
ð¡â² ððð
, ð0 =
ð â²
ð â²ðð
, ð¥ =
ð¥â²
ð â²ðð
, ð£ =
ð£â²ð¡â² ððð
ð â²ðð
, ð0 =
ð â² ð¡â² ððð
ð â²ðð
, ð¢ = ð£ â ðŸâ ð0 , ð =
ðâ²
ðâ²â
, ð =
ðâ²
ðâ
et ð =
ðâ²
ðâ²ð
.
The dimensionless equations of the problem as in [6] take the form:
ðŸâ
ð
ðð
ðð¡
+
2ð ð0
ð¥ + ð0
+ ð0
ð
ðð¥
+
1
(ð¥ + ð0)2
ð (ð¥ + ð0)2
ð ð¢
ðð¥
= 0
ðŸâ
ð
ð
ðð¢
ðð¥
ð0 + ðŸâ ð0 + ð ðŸâ
ðð¢
ðð¡
+ ð¢
ðð¢
ðð¥
= 0
ðŸâ
ð
ðð
ðð¡
+ ð0
ðð
ðð¥
+ ð¢
ðð
ðð¥
=
1
ðð ð ð¶ð(ð¥ + ð0)2
ð
ðð¥
(ð¥ + ð0)2
ð
ðð
ðð¥
(1)
With the initial conditions :
ð 0, ð¥ =
ððð ð¥ , 𥠆0
ðâ ð¥ , ð¥ > 0
(2)
ð 0, ð¥ =
ððð ð¥ , 𥠆0
ðâ ð¥ , ð¥ > 0
(3)
ð¢ 0, ð¥ =
ð¢ðð ð¥ , 𥠆0
ð¢â ð¥ , ð¥ > 0
(4)
The boundary conditions are :
ð ð¡, ð¥ = ðð ð¡, ð¥ , 𥠆0 (5)
lim
ð¥â+â
ð ð¡, ð¥ = ðâ(ð¡) (6)
ð ð¡, ð¥ = ðð ð¡, ð¥ , 𥠆0 (7)
3. Supercritical Evaporation of a Drop
www.ijres.org 43 | Page
lim
ð¥â+â
ð ð¡, ð¥ = ðâ(ð¡) (8)
ð¢ ð¡, ð¥ = ð¢ ð¡, ð¥ , 𥠆0 (9)
lim
ð¥â+â
ð¢ ð¡, ð¥ = ð¢â(ð¡) (10)
And the jump relations are:
ðð ð¢ð = ð ð ð¢ ð (11)
ðð(
ðð
ðð¥
)ð + ðð ðð ð¢ð ð¿0 = ð ð(
ðð
ðð¥
) ð , ð¿0 =
ðâ²ð â ðâ² ð
ð¶ðâ²â
ðâ²â
(12)
ðâ² is the total enthalpy corresponding to the relative motion.
The formalism developed in [6] applies and we obtain in first approximation, the quasi steady equations of the
model:
1
(ð¥ + ð0)2
ð (ð¥ + ð0)2
ð0 ð¢0
ðð¥
= 0
ð0 ðŸâ
ðð¢0
ðð¡
+ ð¢0
ðð¢0
ðð¥
= 0
ð¢0
ðð0
ðð¥
=
1
ðð ð0 ð¶ð0(ð¥ + ð0)2
ð
ðð¥
(ð¥ + ð0)2
ð0
ðð0
ðð¥
, ð0 = ð0
(13)
2. The recession laws
The model equations have been established without the need to clarify the law of state. The developed
formalism is valid in both subcritical and critical or supercritical regimes taking into account the changes that
the critical phenomena introduce in the thermodynamic coefficients.
In critical and supercritical regimes, the thermal conductivity can be written [7, 10] :
ðâ²0 = ðâ²0
ððð
+ ðâ²0
ð¶
+ ðâ²0
ðž
(14)
With :
ðâ² ððð
= ðâ²
â
ðâ²
ðâ
or ðâ²
â
ðâ²
ðâ
, ðâ² ð¶
= ðâ²
ðð |
ðâ²âðâ²
ð¶
ðâ²
ð¶
|â1
3 , ðâ² ðž
= ðâ²
1
ðâ²
ðâ²
ð¶
The first two terms depend only on the temperature while the latter depends only on the density. When the
pressure is constant, ðâ² depends only on the temperature. The heat capacity at constant pressure ð¶â² ð depends
also on the temperature. Experiments and numerical results [7, 8, 9] suggest the existence of two distinct regions
in the flow at critical and moderate supercritical conditions and the existence of a sphere of radius depending on
the initial and boundary conditions out of which the macroscopic variables of the flow do not depend on time.
This ensures the non vanishing of the latent heat ð¿0 and the quasi steady evolution of the flow to the vanishing
of the cold pocket after an unsteady transitional phase.
When ð0 and ð¶ð0 depend only on the temperature, the third relation of the equations (13) can be developed as:
ð2
ð
ðð¥2
+ ð
ðð
ðð¥
+ ð(
ðð
ðð¥
)2
= 0, ð =
2
ð¥ + ð0
â
ð0 ð¶ð0 ð(ð¡)
ð0(ð¥ + ð0)2
, ð =
1
ð0
ðð0
ðð
(15)
We infer from this :
ðð
ðð¥
=
ðð¥ð â ð ð¡, ð£ ðð£
ð¥
0
ð ð¡ + ðœ(ð¡, ð¥)
, ðœ ð¡, ð¥ = ð ð¡, ð€ ðð¥ð â ð ð¡, ð£ ðð£
ð¥
0
ð¥
0
ðð€ (16)
This gives by using the jump relation on the energy conservation
ð ð¡ ð0 = â
ðð0
0
ðŸâ ð¿0
, ð0
0
ð¡ = lim
ð¥â0+
ð0 (17)
By integrating equation (16) we obtain
ð(ð¡)
ð0
0
(ð¡)
=
ðœ(ð¡, ð¥)
ð0(ð) â ð0
0
(ð¡)
(18)
We infer from this by making ð¥ tend towards +â
ð ð¡ =
ð0
0
ðœ(ð¡)
ð0
â
â ð0
0 , ð0
â
= lim
ð¥â+â
ð0 ð(ð¡, ð¥) , ðœ ð¡ = lim
ð¥â+â
ðœ ð¡, ð¥ (19)
In the particular case where ð and
ð¶ð0
ð0
do not depend explicitly on ð¥ , we obtain :
4. Supercritical Evaporation of a Drop
www.ijres.org 44 | Page
ðœ ð¡ =
ð0
2
â ð0
â (
ðð0
ðð
)â exp
â
ð0
â 1 , â=
ðð ð(ð¡)ð¶ð0
â
ð0
â , (
ðð0
ðð
)â = lim
ð¥â+â
ðð0
ðð
(20)
Returning to dimensional variables, we have:
â
ð0
=
ð¢â²0 ðâ²0
ðŸâ²
, ðŸâ² being the thermal diffusivity. Hence we have:
- Near the critical point, ðŸâ² tends towards zero, so
â
ð0
tends towards infinity. The recession law of the
pocket radius is given by the implicit relation :
1
â
exp
â
ð
â 1 ð 2
ðð =
ð
ðð ðŸâ
ð0
â
(ð0
â
â ð0
0
)
ð¿0(
ðð0
ðð
)â
ð¡
0
ðð
ð0
1
(21)
which obviously is not a polynomial law.
- In supercritical regime , ðŸâ² is non zero and as
â
ð0
is small near the critical point, we can make the
approximation exp
â
ð0
â 1 â
â
ð0
and obtain
ð0
2
= 1 â
2ð
ðð ðŸâ
ð0
â
(ð0
â
â ð0
0
)
ð¿0(
ðð0
ðð
)â
ð¡
0
ðð (22)
In the case where the integrand
ð0
â(ð0
ââð0
0
)
ð¿0(
ð ð0
ðð
)â
is constant, we obtain the classical ð2
law.
The formalism we have used doesnât allow establishing the classical recession law of ð2
near the
critical point. Nevertheless, it confirms the validity of the ð2
law in supercritical evaporation.
III. NUMERICAL STUDY OF THE SURPERCRITICAL DROPLET EVAPORATION
The asymptotic analysis made in Section 2 allowed us to deduce the recession laws of the pocket radius of
cold fluid in hotter environment of the same fluid. We now numerically solve the system of conservation
equations to study the macroscopic variables of the flow and to test the validity of the assumptions used in the
previous section. When we introduce a drop or a pocket of cold fluid in a hotter isobaric atmosphere at
supercritical pressure of the same fluid, there may be several types of qualitative behavior depending on the
initial conditions. If the drop is subcritical and the gaseous environment is supercritical initially, the drop passes
through critical state during the evaporation process. If the droplet and its environment are supercritical, there is
a relaxation phenomenon which never passes through the critical state. In our study, we consider only the
second case to avoid taking into account critical divergency and complex laws of recession.
1. Position of the problem
We consider a spherical pocket of carbon dioxide (ð¶ð2 ) of initial radius ðâ²
0 = ð â²ðð , initial density
ðâ²
0 = ðâ²ðð
and initial uniform pressure ðâ²
0 = ðâ²ðð suddenly introduced into a combustion chamber filled
with the same hotter supercritical fluid but at the same constant pressure ðâ²ðð and at uniform density ðâ²â
. The
dimensions of the pocket and the chamber are chosen such that their ratio
ð â²ðð
ð â² ðð
is 10â2
, ð â² ðð is the radius of the
chamber, this gives a ratio 10â6
for the initial volumes of spheres. It is therefore reasonable to assume that the
effects of the disturbance caused by the presence of the pocket reach the walls of the room infinitesimally. We
consider that the process is isobaric throughout its duration at pressure ðâ²ðð . The temperature ðâ²â of the wall of
the room is kept constant. The ratio of initial densities
ðâ²â
ðâ²ðð
of the fluid far from the pocket and in the pocket is
0,6. We have to solve the system of the equations of mass, momentum and energy conservation, the equation of
Van der Waals is the law of the state chosen. The system is written in spherical coordinates and we have:
ððâ²
ðð¡â²
+
1
ðâ²2
ð(ðâ²2
ðâ²
ð£â²
)
ððâ²
= 0
ðâ²
ðð£â²
ðð¡â²
+ ð£â²
ð£â²
ðâ²
= â
ððâ²
ððâ²
ðâ²
ð¶â²
ð£
ððâ²
ðð¡â²
+ ð£â²
ððâ²
ððâ²
=
1
ðâ²2
ð
ððâ²
ðâ²2
ðâ²
ððâ²
ððâ²
â ðâ²
+ ðâ²
ðâ²2 2ð£â²
ðâ²
+
ðð£â²
ððâ²
ðâ²
=
ðâ²ð â²ðâ²
1 â ðâ²ðâ²
â ðâ²
ðâ²2
(23)
The initial conditions on the density and temperature are given by:
5. Supercritical Evaporation of a Drop
www.ijres.org 45 | Page
ðâ²
ðâ²
, 0 =
ðâ²ðð
ðâ²
†ð â²
ðð
ðâ²â
ðâ²
> ð â²
ðð
(24)
ðâ²
ðâ²
, 0 =
ðâ²ðð ðâ²
†ð â²
ðð
ðâ²â ðâ²
> ð â²
ðð
(25)
The thermal conductivity is calculated as
ðâ²
ðâ²
= ðâ²
0
ðâ²
ðâ²
ð
+ 0,078
ðâ²
ðâ²
ð
+ 0,014
ðâ²
ðâ²
ð
â 1
â1
3
(26)
As in [11], the specific heat at constant volume ðâ² ð£ is assumed constant and equal to the ideal gas specific heat.
Similarly, the parameters ðâ²and ðâ² are calculated using experimental values of the critical temperature and
pressure for ð¶ð2. We put the macroscopic variables into dimensionless form by setting ð =
ðâ²
ðâ² ð
, ð =
ðâ²
ðâ²â
,
ð =
ðâ²
ðâ² ð ð â²ðâ² ð
, ðâ² ð
and ðâ² ð are the critical values of the density and temperature of ð¶ð2. We introduce the
characteristic velocity ðâ² of the flow and the Mach number ðð =
ðâ²
ð¶â²0
, where ð¶â² ð is the sound velocity
calculated in the ideal gas at temperature ðâ² ð . Then, the dimensionless time and velocity are given by ð¡ =
ðâ²ð¡â²
ð â²ðð
and ð£ =
ð£â²
ðâ²0
. It is assumed that the flow is a low Mach number flow. The formalism used is the same as in [11,
14]. An asymptotic expansion in terms of the parameter ðð allows having in first approximation the following
system [14, 15]:
ðð0
ðð¡
+
1
ð2
ð(ð2
ð0 ð£0)
ðð
= 0
ðð0
ðð
= 0
ð0
ðð£0
ðð¡
+ ð£0
ðð£0
ðð
= â
1
ðŸ
ðð1
ðð
ð0
ðð0
ðð¡
+ ð£0
ðð0
ðð
=
ð¡â²
ð
ð¡â²
ððð
ðŸ
ðð
1
ð2
ð
ðð
ð2
ð
ðð0
ðð
â ðŸ â 1 ð0 +
9
8
ð0
2
2ð£0
ð
+
ðð£0
ðð
ð0 =
ð0 ð0
1 â
ð0
3
â
9
8
ð0
2
(27)
This system is then solved by a finite volume code using the SIMPLER algorithm [12, 14].
2. The numerical results
The numerical computations have been performed for ð =
ðâ²â
ðâ²ðð
= 0,6 and
ðâ²ââðâ²ðð
ðâ²ðð
= 10â5
. The initial
configuration is slightly supercritical and we assume that the initial density of the drop is the critical density
of ð¶ð2. Hence we have ððð = 1.
2.1 Results for the temperature and the density
Figure 1 and figure 2 represent respectively the evolution of the temperature (ðððð = ð =
ðâ²
ðâ²â
) and the
density (ððð =
ðâ²
ðâ²ðð
) of the flow at different times versus ð, the ratio of the distance to the center of the droplet
and the initial radius of the droplet (
ðâ²
ð â²ðð
).
6. Supercritical Evaporation of a Drop
www.ijres.org 46 | Page
Figure 1: Temperature evolution at different times Figure 2: density evolution at different times
The initial conditions induce the partition of the flow domain into three separate zones: two steady zones
which are the inner of the drop and the surrounding gas separated by a very thin transition layer in the beginning
of the process. This transition layer whose thickness depends on the time, gradually expands to invade the entire
flow field.
In contrast with the quasi-steady approximation and surely due to the constancy of the macroscopic
variables in the drop and in the gaseous environment far from the drop and out of the transition zone, the
temperature and density profiles are monotonic. They are increasing for the temperature and decreasing for the
density in the transition layer.
2.2 Results for the mass flow
The figures 3.a and 3.b show the evolution of the mass flow at different times as function of ð. The initial
velocity was taken zero throughout the flow so the initial mass flow is zero both in the drop and in the hotter gas
environment. Subsequent changes are therefore due to the discontinuities in the initial and boundary conditions
of the temperature and the density. The profiles of the mass flow show generally at the beginning of the process
two shocks which are represented by a maximum and a minimum of the mass flow. These shocks occur in a
very small neighborhood on both sides of the drop border. The first shock is due to thermal discontinuities in the
vicinity of the border of the pocket and leads to a maximum of the mass flow. The value of this maximum is not
a monotonic function of time. It increases from the beginning of the process until a time ð¡ ððð¥ at which it begins
to decrease.
Figure 3: Mass flow evolution at different times
The second shock is due to mass discontinuities in the vicinity of the border and leads to a minimum of the
mass flow. Its value is also a non-monotonic function of time and behaves as the maximum. The only difference
is that it is canceled before the maximum which disappears with the drop. In addition, we clearly notice on the