This document summarizes a presentation on simulating hydrogen-assisted crack initiation in steel. It describes developing a finite element model to simulate hydrogen diffusion and crack propagation. Experimental results showed the base metal was resistant to hydrogen embrittlement while the heat-affected zone was susceptible. The model used cohesive elements with hydrogen-dependent properties to simulate cracking. Simulation results matched experiments and could evaluate fracture integrity of welded joints. The work was funded by industry to develop understanding of deepwater pipeline welding.
1) A model was developed to understand the sharp transition between copper oxide phases observed during CVD. The model considers oxygen transport and the single degree of freedom in the Cu2O-O2-CuO system.
2) 1D and 2D models were used to predict spatial oxygen profiles and examine the effects of temperature, oxygen flow, and surface/gas phase reaction rates on the transition location.
3) Comparisons to experimental film measurements suggest surface reactions play a primary role in the transition, though gas phase reactions may also contribute. Further work aims to estimate adsorption rates and refine surface/gas phase reaction mechanisms.
Preheating effects in Electron Beam Additive ManufacturingNinggang Shen
This document presents research on numerical thermal analysis of electron beam additive manufacturing with preheating effects. It includes background on the technology, objectives to study preheating processes and multi-layer scanning simulations, and outlines thermal modeling and finite element analysis methods. Simulation results show that preheating penetration is around 0.5mm, substrates thicker than 10mm critically affect results, and multi-layer scanning causes differences in melt pool geometry and temperature distributions compared to single scans.
1) The document describes a study to develop a continuous gradient assisted hydrophobic interaction chromatography process using Simulated Moving Bed (SMB-HIC) for the purification of recombinant streptokinase (rec-stk) from E. coli cell homogenate.
2) Key steps included producing and purifying rec-stk, estimating adsorption isotherms, designing a 3-zone open loop SMB system using a scanning program, and experimental realization of the SMB process.
3) Simulation studies were conducted to identify separation regions using equilibrium theory and stage models, and operating points were selected for experimental validation of the continuous purification of rec-stk via SMB-HIC.
This document summarizes a milling workshop that discussed:
1. Issues with milling processes like selecting appropriate mills through trial and error.
2. Factors that affect milling like energy utilization, material properties, and methods of stressing particles.
3. Models for describing energy utilization in milling and relationships between product characteristics and mill dynamics based on single particle breakage experiments and mechanical properties.
This document provides supplementary information for a research article on three-dimensional bicontinuous ultrafast charge and discharge bulk battery electrodes. It includes 6 tables and 8 figures that provide additional experimental details, results, and characterization data. Specifically, it reports electron conductivities and ion diffusion coefficients for various cathode materials, shows FCC structures of templates and relationships between porosity and template parameters, and includes discharge curves, cycling performance, and material characterization such as XRD and XPS for NiOOH and MnO2 electrodes fabricated in the study.
M A S S T R A N S F E R O P E R A T I O N S I J N T U M O D E L P A P E...guest3f9c6b
This document contains questions from a Mass Transfer Operations exam. It includes 8 questions related to various mass transfer topics like classification of mass transfer operations, diffusion, distillation design, and mass transfer correlations. The questions involve calculations related to diffusion rates, mass transfer coefficients, distillation column design parameters, and phase equilibrium data.
The International Journal of Engineering and Sciencetheijes
The document summarizes research on the dielectric, magnetic, electric, and structural properties of Ni0.2-Cox-Zn0.8-x ferrite nanoparticles synthesized using a sol-gel auto combustion method. X-ray diffraction analysis showed the particles crystallized in the spinel ferrite structure. Scanning electron microscopy revealed the particles had compact structures smaller than 60 nm. Fourier transform infrared spectroscopy confirmed the presence of ferrite functional groups. Magnetic properties such as saturation magnetization increased with higher Co-Zn concentration. Dielectric properties varied with sintering temperature.
1) A model was developed to understand the sharp transition between copper oxide phases observed during CVD. The model considers oxygen transport and the single degree of freedom in the Cu2O-O2-CuO system.
2) 1D and 2D models were used to predict spatial oxygen profiles and examine the effects of temperature, oxygen flow, and surface/gas phase reaction rates on the transition location.
3) Comparisons to experimental film measurements suggest surface reactions play a primary role in the transition, though gas phase reactions may also contribute. Further work aims to estimate adsorption rates and refine surface/gas phase reaction mechanisms.
Preheating effects in Electron Beam Additive ManufacturingNinggang Shen
This document presents research on numerical thermal analysis of electron beam additive manufacturing with preheating effects. It includes background on the technology, objectives to study preheating processes and multi-layer scanning simulations, and outlines thermal modeling and finite element analysis methods. Simulation results show that preheating penetration is around 0.5mm, substrates thicker than 10mm critically affect results, and multi-layer scanning causes differences in melt pool geometry and temperature distributions compared to single scans.
1) The document describes a study to develop a continuous gradient assisted hydrophobic interaction chromatography process using Simulated Moving Bed (SMB-HIC) for the purification of recombinant streptokinase (rec-stk) from E. coli cell homogenate.
2) Key steps included producing and purifying rec-stk, estimating adsorption isotherms, designing a 3-zone open loop SMB system using a scanning program, and experimental realization of the SMB process.
3) Simulation studies were conducted to identify separation regions using equilibrium theory and stage models, and operating points were selected for experimental validation of the continuous purification of rec-stk via SMB-HIC.
This document summarizes a milling workshop that discussed:
1. Issues with milling processes like selecting appropriate mills through trial and error.
2. Factors that affect milling like energy utilization, material properties, and methods of stressing particles.
3. Models for describing energy utilization in milling and relationships between product characteristics and mill dynamics based on single particle breakage experiments and mechanical properties.
This document provides supplementary information for a research article on three-dimensional bicontinuous ultrafast charge and discharge bulk battery electrodes. It includes 6 tables and 8 figures that provide additional experimental details, results, and characterization data. Specifically, it reports electron conductivities and ion diffusion coefficients for various cathode materials, shows FCC structures of templates and relationships between porosity and template parameters, and includes discharge curves, cycling performance, and material characterization such as XRD and XPS for NiOOH and MnO2 electrodes fabricated in the study.
M A S S T R A N S F E R O P E R A T I O N S I J N T U M O D E L P A P E...guest3f9c6b
This document contains questions from a Mass Transfer Operations exam. It includes 8 questions related to various mass transfer topics like classification of mass transfer operations, diffusion, distillation design, and mass transfer correlations. The questions involve calculations related to diffusion rates, mass transfer coefficients, distillation column design parameters, and phase equilibrium data.
The International Journal of Engineering and Sciencetheijes
The document summarizes research on the dielectric, magnetic, electric, and structural properties of Ni0.2-Cox-Zn0.8-x ferrite nanoparticles synthesized using a sol-gel auto combustion method. X-ray diffraction analysis showed the particles crystallized in the spinel ferrite structure. Scanning electron microscopy revealed the particles had compact structures smaller than 60 nm. Fourier transform infrared spectroscopy confirmed the presence of ferrite functional groups. Magnetic properties such as saturation magnetization increased with higher Co-Zn concentration. Dielectric properties varied with sintering temperature.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help boost feelings of calmness, happiness and focus.
1. The document discusses corporate blogging, providing statistics on corporate blogs and reasons why companies should have blogs.
2. It outlines the key elements of an effective corporate blog, including regular content updates, a clear focus or topic, and marketing the blog internally and externally.
3. Examples are given of large tech companies like Microsoft and HP that have many corporate blogs that track projects, share knowledge, and promote their brands.
We all know Agile leaders foster self-organization, so why do many have little effect on their teams, or worse, actually harm their effectiveness? People act in ways that are rational to them, but differences in internal mental models can make people seem irrational to us. By uncovering your team’s mental models, you can help them achieve a common rationale. This leads to stronger, integrated teams.
Team Mind - What Can Agile Teams Learn from Team ScienceDerek W. Wade
The document discusses several topics related to team mental models and shared understanding in teams, including:
1) The effects of shared mental models on team performance and processes in submarine attack teams.
2) What skills and knowledge science teams and agile teams share and can learn from each other.
3) The concept of boundary objects and how they can help develop shared understanding.
This document discusses the design of a lithium target and neutronics components for a boron neutron capture therapy (BNCT) facility. It outlines the agenda, describes the target geometry and materials, and discusses factors like target heat, neutron moderation, reflector design, and beam quality parameters. The goal is to optimize the design to produce the highest possible epithermal neutron flux within safety limits on fast neutron and gamma doses. A series of design studies are proposed to evaluate moderating materials, proton beam energy, reflector configuration, and other variables.
This document discusses 3D MAX phase materials and 2D MXene materials derived from MAX phases. MAX phases have a chemical formula of Mn+1AXn and are a class of materials that bridge the properties of metals and ceramics. They possess good electrical and thermal conductivity as well as high strength and oxidation resistance at high temperatures. The document outlines research being conducted on MAX phases including predicting new phases, studying solid solution strengthening, and investigating superconducting MAX phases. MXenes are 2D carbides, nitrides, and carbonitrides produced by etching away the A-group element from MAX phases. They exhibit promising properties for applications such as energy storage.
This document reviews computational fluid dynamics (CFD) analysis and experimental work on the laser ablation process for producing carbon nanotubes. It discusses how CFD can be used to simulate the plume dynamics and temperature/pressure profiles during laser ablation. While some studies have performed 2D analysis of the furnace geometry, the document suggests there is still scope for 3D CFD analysis to better understand the phenomena. It surveys several past experimental and computational investigations on laser ablation for nanotube production.
This document discusses opportunities for using nanotechnology to improve energy applications. It notes that nanomaterials have increased surface areas and unique interface and size effects that can be exploited. Examples highlighted include using nanostructures to improve photovoltaics, hydrogen storage, and thermoelectric devices. Challenges include developing scalable synthesis methods and understanding multiscale transport phenomena. Overall, the document argues that nanoscience research has potential to transform energy technologies by manipulating energy carriers at the nanoscale and linking structures to functions.
Investigation of heat transfer through cnt composites focusing on conduction ...iaemedu
This document summarizes a study that investigated the heat transfer properties of carbon nanotube (CNT) composites, with a focus on conduction mode heat transfer. Multi-wall carbon nanotubes were synthesized using chemical vapor deposition inside anodic aluminum oxide templates to create aligned CNT composites. Randomly oriented CNT and graphite films were also prepared. Specific heat capacity and thermal conductivity measurements from 300-400K revealed that aligned CNT composites had higher thermal conductivity than randomly oriented films, demonstrating the anisotropic heat transfer properties of aligned CNT structures. Randomly oriented CNT and graphite films showed similar thermal properties.
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
1. The document investigates heat transfer through carbon nanotube composites, focusing on the conduction mode.
2. It summarizes the synthesis and preparation of aligned multi-walled carbon nanotube samples embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The specific heat and thermal conductivity of the samples are measured from 300 to 400K. The specific heat of the aligned nanotube sample has weaker temperature dependence than the random films and bulk graphite. The thermal conductivity of the aligned sample increases with temperature, while the random films and graphite show a
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
This document summarizes a study that investigated the heat transfer properties of carbon nanotube (CNT) composites, with a focus on conduction mode heat transfer. Multi-wall carbon nanotubes were synthesized using chemical vapor deposition inside anodic aluminum oxide templates to create aligned CNT composites. Randomly oriented CNT and graphite films were also prepared. Specific heat capacity and thermal conductivity were measured for the different materials from 300-400K using an AC calorimetric technique. Results showed the aligned CNT composite had higher thermal conductivity than the random films, demonstrating the anisotropic heat transfer along the CNT axes.
Investigation of heat transfer through cnt composites focusing on conduction ...iaemedu
1. The document investigates the heat transfer properties of carbon nanotube composites, focusing on the conduction mode of heat transfer.
2. It analyzes the specific heat and thermal conductivity of aligned multi-walled carbon nanotubes embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The results show that the specific heat of the randomly oriented films is similar to bulk graphite powder, while the aligned nanotubes have a weaker temperature dependence. The thermal conductivity of the randomly oriented films behaves similarly to graphite and is dominated by phonon boundary scattering, while
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
1. The document investigates the heat transfer properties of carbon nanotube composites, focusing on the conduction mode of heat transfer.
2. It analyzes the specific heat and thermal conductivity of aligned multi-walled carbon nanotubes embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The results show that the specific heat of the randomly oriented films is similar to bulk graphite powder, while the aligned nanotubes have a weaker temperature dependence. The thermal conductivity of the randomly oriented films behaves similarly to graphite and is dominated by phonon boundary scattering, while
Study of Boron Based Superconductivity and Effect of High Temperature Cuprate...IOSR Journals
This paper illustrates the main normal and Boron superconducting state temperature properties of magnesium diboride, a substance known since early 1950's, but lately graded to be superconductive at a remarkably high critical temperature Tc=40K for a binary synthesis. What makes MgB2 so special? Its high Tc, simple crystal construction, large coherence lengths, high serious current densities and fields, lucidity of surface boundaries to current promises that MgB2 will be a good material for both large scale applications and electronic devices. Throughout the last seven month, MgB2 has been fabricated in various shape, bulk, single crystals, thin films, ribbons and wires. The largest critical current densities >10MA/cm2 and critical fields 40T are achieved for thin films. The anisotropy attribution inferred from upper critical field measurements is still to be resolved, a wide range of values being reported, γ = 1.2 ÷ 9. Also there is no consensus about the existence of a single anisotropic or double energy cavity. One central issue is whether or not MgB2 represents a new class of superconductors, being the tip of an iceberg that waits to be discovered. Until now MgB2 holds the record of the highest Tc among simple binary synthesis. However, the discovery of superconductivity in MgB2 revived the interest in non-oxides and initiated a search for superconductivity in related materials, several synthesis being already announced to become superconductive: TaB2, BeB2.75, C-S composites, and the elemental B under pressure.
201606_Ferrites,_CMC,_and_Power_Transformer_(1)eRay Lai
The document discusses soft ferrite specifications for CMCs, power chokes, and transformers. It begins by explaining the importance but also limitations of the B-H curve as a characterization of ferrite materials. Key specifications discussed include permeability, saturation flux density, core loss density, and effective bandwidth. However, the document notes that permeability is nonlinear and dependent on factors like temperature, frequency, and load/current. Real applications also involve more complex geometries compared to an idealized toroid shape. Overall, both material properties from the B-H curve as well as mechanical design aspects are important for magnetic component design.
Development of high temperature magnetic bearingsjinfangliu
The document discusses a NASA/Electron Energy Corporation (EEC) Small Business Innovation Research (SBIR) project to develop high temperature permanent magnet biased magnetic bearings and motors. The project aims to utilize EEC's patented SmCo magnets that can operate up to 550°C to develop a technology demonstrator operating at 540°C, including a motor and radial/thrust magnetic bearings. Bench tests of a designed radial bearing show it can produce over 2800N of force at 500°C, around 86% of room temperature performance. A solid model and test apparatus are presented, demonstrating progress toward the project goals.
IRJET- Thermomagnetic-Gravitational Convection in a Vertical Layer of Fer...IRJET Journal
This document summarizes research on thermomagnetic-gravitational convection in a vertical layer of ferrofluid between two differentially heated plates in an applied magnetic field. It investigates the linear stability of the system for varying governing parameters. Three main types of instability patterns are observed corresponding to thermo-gravitational, magnetic, and magneto-gravitational convection. An oblique external magnetic field introduces asymmetry and qualitatively changes stability characteristics compared to a normal field case, preferentially shifting instability structures toward the hot wall. For each field inclination angle, there exists an orientation angle that most promotes magneto-gravitational instability onset. Dimensionless governing equations are derived and linearized perturbation equations in normal mode
IRJET- Thermomagnetic-Gravitational Convection in a Vertical Layer of Ferrofl...IRJET Journal
This document summarizes research on thermomagnetic-gravitational convection in a vertical layer of ferrofluid between two differentially heated plates in an applied magnetic field. It investigates the linear stability of the system for varying governing parameters. Three main types of instability patterns are observed corresponding to thermo-gravitational, magnetic, and magneto-gravitational convection. An oblique external magnetic field introduces asymmetry and qualitatively changes stability characteristics compared to a normal field case, preferentially shifting instability structures toward the hot wall. For each field inclination angle, there exists an orientation angle that most promotes magneto-gravitational instability onset. Dimensionless governing equations are derived and linearized perturbation equations in normal mode
There is nowadays a growing need for sensing devices offering rapid and portable analytical functionality in real-time as well as massively parallel capabilities with very high sensitivity at the molecular level. Such devices are essential to facilitate research and foster advances in fields such as drug discovery, proteomics, medical diagnostics, systems biology or environmental monitoring.
In this context, an ideal solution is an ion-sensitive field-effect transistor sensor platform based on silicon nanowires to be integrated in a CMOS architecture. Indeed, in addition to the expected high sensitivity and superior signal quality, such nanowire sensors could be mass manufactured at reasonable costs, and readily integrated into electronic diagnostic devices to facilitate bed-site diagnostics and personalized medicine. Moreover, their small size makes them ideal candidates for future implanted sensing devices. While promising biosensing experiments based on silicon nanowire field-effect transistors have been reported, real-life applications still require improved control, together with a detailed understanding of the basic sensing mechanisms. For instance, it is crucial to optimize the geometry of the wire, a still rather unexplored aspect up to now, as well as its surface functionalization or its selectivity to the targeted analytes.
This project seeks to develop a modular, scalable and integrateable sensor platform for the electronic detection of analytes in solution. The idea is to integrate silicon nanowire field-effect transistors as a sensor array and combine them with state-of-the-art microfabricated interface electronics as well as with microfluidic channels for liquid handling. Such sensors have the potential to be mass manufactured at reasonable costs, allowing their integration as the active sensor part in electronic point-of-care diagnostic devices to facilitate, for instance, bed-side diagnostics and personalized medicine. Another important field is systems biology, where many substances need to be quantitatively detected in parallel at very low concentrations: in these situations, the platform being developed fulfills the requirements ideally and will have a strong impact and provide new insights, e.g. into the metabolic processes of cells, organisms or organs.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help boost feelings of calmness, happiness and focus.
1. The document discusses corporate blogging, providing statistics on corporate blogs and reasons why companies should have blogs.
2. It outlines the key elements of an effective corporate blog, including regular content updates, a clear focus or topic, and marketing the blog internally and externally.
3. Examples are given of large tech companies like Microsoft and HP that have many corporate blogs that track projects, share knowledge, and promote their brands.
We all know Agile leaders foster self-organization, so why do many have little effect on their teams, or worse, actually harm their effectiveness? People act in ways that are rational to them, but differences in internal mental models can make people seem irrational to us. By uncovering your team’s mental models, you can help them achieve a common rationale. This leads to stronger, integrated teams.
Team Mind - What Can Agile Teams Learn from Team ScienceDerek W. Wade
The document discusses several topics related to team mental models and shared understanding in teams, including:
1) The effects of shared mental models on team performance and processes in submarine attack teams.
2) What skills and knowledge science teams and agile teams share and can learn from each other.
3) The concept of boundary objects and how they can help develop shared understanding.
This document discusses the design of a lithium target and neutronics components for a boron neutron capture therapy (BNCT) facility. It outlines the agenda, describes the target geometry and materials, and discusses factors like target heat, neutron moderation, reflector design, and beam quality parameters. The goal is to optimize the design to produce the highest possible epithermal neutron flux within safety limits on fast neutron and gamma doses. A series of design studies are proposed to evaluate moderating materials, proton beam energy, reflector configuration, and other variables.
This document discusses 3D MAX phase materials and 2D MXene materials derived from MAX phases. MAX phases have a chemical formula of Mn+1AXn and are a class of materials that bridge the properties of metals and ceramics. They possess good electrical and thermal conductivity as well as high strength and oxidation resistance at high temperatures. The document outlines research being conducted on MAX phases including predicting new phases, studying solid solution strengthening, and investigating superconducting MAX phases. MXenes are 2D carbides, nitrides, and carbonitrides produced by etching away the A-group element from MAX phases. They exhibit promising properties for applications such as energy storage.
This document reviews computational fluid dynamics (CFD) analysis and experimental work on the laser ablation process for producing carbon nanotubes. It discusses how CFD can be used to simulate the plume dynamics and temperature/pressure profiles during laser ablation. While some studies have performed 2D analysis of the furnace geometry, the document suggests there is still scope for 3D CFD analysis to better understand the phenomena. It surveys several past experimental and computational investigations on laser ablation for nanotube production.
This document discusses opportunities for using nanotechnology to improve energy applications. It notes that nanomaterials have increased surface areas and unique interface and size effects that can be exploited. Examples highlighted include using nanostructures to improve photovoltaics, hydrogen storage, and thermoelectric devices. Challenges include developing scalable synthesis methods and understanding multiscale transport phenomena. Overall, the document argues that nanoscience research has potential to transform energy technologies by manipulating energy carriers at the nanoscale and linking structures to functions.
Investigation of heat transfer through cnt composites focusing on conduction ...iaemedu
This document summarizes a study that investigated the heat transfer properties of carbon nanotube (CNT) composites, with a focus on conduction mode heat transfer. Multi-wall carbon nanotubes were synthesized using chemical vapor deposition inside anodic aluminum oxide templates to create aligned CNT composites. Randomly oriented CNT and graphite films were also prepared. Specific heat capacity and thermal conductivity measurements from 300-400K revealed that aligned CNT composites had higher thermal conductivity than randomly oriented films, demonstrating the anisotropic heat transfer properties of aligned CNT structures. Randomly oriented CNT and graphite films showed similar thermal properties.
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
1. The document investigates heat transfer through carbon nanotube composites, focusing on the conduction mode.
2. It summarizes the synthesis and preparation of aligned multi-walled carbon nanotube samples embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The specific heat and thermal conductivity of the samples are measured from 300 to 400K. The specific heat of the aligned nanotube sample has weaker temperature dependence than the random films and bulk graphite. The thermal conductivity of the aligned sample increases with temperature, while the random films and graphite show a
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
This document summarizes a study that investigated the heat transfer properties of carbon nanotube (CNT) composites, with a focus on conduction mode heat transfer. Multi-wall carbon nanotubes were synthesized using chemical vapor deposition inside anodic aluminum oxide templates to create aligned CNT composites. Randomly oriented CNT and graphite films were also prepared. Specific heat capacity and thermal conductivity were measured for the different materials from 300-400K using an AC calorimetric technique. Results showed the aligned CNT composite had higher thermal conductivity than the random films, demonstrating the anisotropic heat transfer along the CNT axes.
Investigation of heat transfer through cnt composites focusing on conduction ...iaemedu
1. The document investigates the heat transfer properties of carbon nanotube composites, focusing on the conduction mode of heat transfer.
2. It analyzes the specific heat and thermal conductivity of aligned multi-walled carbon nanotubes embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The results show that the specific heat of the randomly oriented films is similar to bulk graphite powder, while the aligned nanotubes have a weaker temperature dependence. The thermal conductivity of the randomly oriented films behaves similarly to graphite and is dominated by phonon boundary scattering, while
Investigation of heat transfer through cnt composites focusing on conduction ...IAEME Publication
1. The document investigates the heat transfer properties of carbon nanotube composites, focusing on the conduction mode of heat transfer.
2. It analyzes the specific heat and thermal conductivity of aligned multi-walled carbon nanotubes embedded in anodic aluminum oxide templates, as well as randomly oriented films of multi-walled carbon nanotubes, single-walled carbon nanotubes, and graphite powder.
3. The results show that the specific heat of the randomly oriented films is similar to bulk graphite powder, while the aligned nanotubes have a weaker temperature dependence. The thermal conductivity of the randomly oriented films behaves similarly to graphite and is dominated by phonon boundary scattering, while
Study of Boron Based Superconductivity and Effect of High Temperature Cuprate...IOSR Journals
This paper illustrates the main normal and Boron superconducting state temperature properties of magnesium diboride, a substance known since early 1950's, but lately graded to be superconductive at a remarkably high critical temperature Tc=40K for a binary synthesis. What makes MgB2 so special? Its high Tc, simple crystal construction, large coherence lengths, high serious current densities and fields, lucidity of surface boundaries to current promises that MgB2 will be a good material for both large scale applications and electronic devices. Throughout the last seven month, MgB2 has been fabricated in various shape, bulk, single crystals, thin films, ribbons and wires. The largest critical current densities >10MA/cm2 and critical fields 40T are achieved for thin films. The anisotropy attribution inferred from upper critical field measurements is still to be resolved, a wide range of values being reported, γ = 1.2 ÷ 9. Also there is no consensus about the existence of a single anisotropic or double energy cavity. One central issue is whether or not MgB2 represents a new class of superconductors, being the tip of an iceberg that waits to be discovered. Until now MgB2 holds the record of the highest Tc among simple binary synthesis. However, the discovery of superconductivity in MgB2 revived the interest in non-oxides and initiated a search for superconductivity in related materials, several synthesis being already announced to become superconductive: TaB2, BeB2.75, C-S composites, and the elemental B under pressure.
201606_Ferrites,_CMC,_and_Power_Transformer_(1)eRay Lai
The document discusses soft ferrite specifications for CMCs, power chokes, and transformers. It begins by explaining the importance but also limitations of the B-H curve as a characterization of ferrite materials. Key specifications discussed include permeability, saturation flux density, core loss density, and effective bandwidth. However, the document notes that permeability is nonlinear and dependent on factors like temperature, frequency, and load/current. Real applications also involve more complex geometries compared to an idealized toroid shape. Overall, both material properties from the B-H curve as well as mechanical design aspects are important for magnetic component design.
Development of high temperature magnetic bearingsjinfangliu
The document discusses a NASA/Electron Energy Corporation (EEC) Small Business Innovation Research (SBIR) project to develop high temperature permanent magnet biased magnetic bearings and motors. The project aims to utilize EEC's patented SmCo magnets that can operate up to 550°C to develop a technology demonstrator operating at 540°C, including a motor and radial/thrust magnetic bearings. Bench tests of a designed radial bearing show it can produce over 2800N of force at 500°C, around 86% of room temperature performance. A solid model and test apparatus are presented, demonstrating progress toward the project goals.
IRJET- Thermomagnetic-Gravitational Convection in a Vertical Layer of Fer...IRJET Journal
This document summarizes research on thermomagnetic-gravitational convection in a vertical layer of ferrofluid between two differentially heated plates in an applied magnetic field. It investigates the linear stability of the system for varying governing parameters. Three main types of instability patterns are observed corresponding to thermo-gravitational, magnetic, and magneto-gravitational convection. An oblique external magnetic field introduces asymmetry and qualitatively changes stability characteristics compared to a normal field case, preferentially shifting instability structures toward the hot wall. For each field inclination angle, there exists an orientation angle that most promotes magneto-gravitational instability onset. Dimensionless governing equations are derived and linearized perturbation equations in normal mode
IRJET- Thermomagnetic-Gravitational Convection in a Vertical Layer of Ferrofl...IRJET Journal
This document summarizes research on thermomagnetic-gravitational convection in a vertical layer of ferrofluid between two differentially heated plates in an applied magnetic field. It investigates the linear stability of the system for varying governing parameters. Three main types of instability patterns are observed corresponding to thermo-gravitational, magnetic, and magneto-gravitational convection. An oblique external magnetic field introduces asymmetry and qualitatively changes stability characteristics compared to a normal field case, preferentially shifting instability structures toward the hot wall. For each field inclination angle, there exists an orientation angle that most promotes magneto-gravitational instability onset. Dimensionless governing equations are derived and linearized perturbation equations in normal mode
There is nowadays a growing need for sensing devices offering rapid and portable analytical functionality in real-time as well as massively parallel capabilities with very high sensitivity at the molecular level. Such devices are essential to facilitate research and foster advances in fields such as drug discovery, proteomics, medical diagnostics, systems biology or environmental monitoring.
In this context, an ideal solution is an ion-sensitive field-effect transistor sensor platform based on silicon nanowires to be integrated in a CMOS architecture. Indeed, in addition to the expected high sensitivity and superior signal quality, such nanowire sensors could be mass manufactured at reasonable costs, and readily integrated into electronic diagnostic devices to facilitate bed-site diagnostics and personalized medicine. Moreover, their small size makes them ideal candidates for future implanted sensing devices. While promising biosensing experiments based on silicon nanowire field-effect transistors have been reported, real-life applications still require improved control, together with a detailed understanding of the basic sensing mechanisms. For instance, it is crucial to optimize the geometry of the wire, a still rather unexplored aspect up to now, as well as its surface functionalization or its selectivity to the targeted analytes.
This project seeks to develop a modular, scalable and integrateable sensor platform for the electronic detection of analytes in solution. The idea is to integrate silicon nanowire field-effect transistors as a sensor array and combine them with state-of-the-art microfabricated interface electronics as well as with microfluidic channels for liquid handling. Such sensors have the potential to be mass manufactured at reasonable costs, allowing their integration as the active sensor part in electronic point-of-care diagnostic devices to facilitate, for instance, bed-side diagnostics and personalized medicine. Another important field is systems biology, where many substances need to be quantitatively detected in parallel at very low concentrations: in these situations, the platform being developed fulfills the requirements ideally and will have a strong impact and provide new insights, e.g. into the metabolic processes of cells, organisms or organs.
The document summarizes a workshop on limiting factors in high temperature electrolysis. It discusses environmental and resource concerns motivating hydrogen production from electrolysis. Renewable and nuclear energy could power electrolysis to produce hydrogen for storage or conversion to synthetic fuels. Key challenges include electrolyzer durability, thermodynamics, heat management, and costs. Large-scale electrolysis tests demonstrate feasibility but further advances are needed for commercialization.
Analysis of polymer polymethyl metha-acralyte and single-wall cnt compositesIAEME Publication
This document discusses analysis of polymer composites made of polymethyl-metha-acrylate (PMMA) and single-wall carbon nanotubes (SWCNTs). Modulation calorimetry techniques such as ACC and MDSC are used to study the thermal properties and glass transition dynamics of the composites. The ACC results show that the effective thermal conductivity of the composites increases with higher SWCNT content, agreeing with theoretical models. MDSC indicates the SWCNTs may quench glassy structural dynamics in PMMA and reduce the hysteresis between heating and cooling curves. Overall the study analyzes the thermal properties of PMMA-SWCNT composites using advanced calorimetry methods.
This document reviews carbon nanotube gas sensors for large-scale applications. It discusses fabrication methods for carbon nanotubes including chemical vapor deposition and dielectrophoresis assembly. Experimental results are presented for carbon nanotube mat gas sensors that detect NO2 at concentrations as low as 50 ppb. Decorating the carbon nanotubes with palladium nanoparticles is shown to enhance the gas sensing performance and response times. Applied voltages are found to control the sensor responses by changing the Schottky barrier formation between the carbon nanotubes and electrodes.
Enhancing the working temperature span and refrigerant capacity of two-phase...Universidad de Oviedo
The document discusses enhancing the working temperature span and refrigerant capacity of two-phase composite systems based on amorphous FeZrBCu ribbons. It first introduces the magnetocaloric effect and improving the relative cooling power through composite compounds. It then presents results on the magnetocaloric properties of FeZrBCu amorphous alloys, including their tunable Curie temperatures and large magnetic entropy changes. The advantages of using these alloys in two-phase composite systems are discussed.
Magnetic,Optical And Thermal Studies of Ppy/Bafetio NanocompositeIJERDJOURNAL
ABSTRACT: This paper presents investigations on magnetic,optical and thermal properties of Ti doped barium ferrite substituted PPY nanocomposite prepared by impregnation technique
Magnetic,Optical And Thermal Studies of Ppy/Bafetio Nanocomposite
Euro Corr2010
1. Cohesive simulation of hydrogen
assisted crack initiation in X70
steel and welded joints
Presentation at EuroCorr2010, Moscow, 13.-17.
September 2010
V. Olden(SINTEF), O. M. Akselsen (SINTEF/NTNU), H. Fjær
(IFE)
Materials and Chemistry 1
2. Content
Background
Description of the FE model
Experimental and FE simulation results
Main conclusions
Materials and Chemistry 2
3. Deep water repair welding and hot tapping
(DEEPIT 2009-2013)
The overall objective is to establish basic
understanding of deep water pipeline repair Budget: 26 mill NOK
welding and hot tapping.
Subgoals:
Develop fundamental knowledge on Participants:
hyperbaric welding technology for full SINTEF, IFE,
remote control in welding of normal pipes
and clad pipes. NTNU, StatoilHydro,
Study the behaviour of different Gassco, Technip and EFD
consumables and shielding gas
Develop mathematical models for
electromagnetic induction heating. The project is open for new
Develop relevant models for simulation of participants
heat flow in hyperbaric MIG with different
bevel configurations.
To develop models tailored for cold
cracking susceptibility predictions
capturing hydrogen pickup, diffusion,
microstructure evolution, restraint
intensity, and integrity assessment.
Materials and Chemistry
4. PRS
Recent large projects:
Hyperbaric Welding Langeled (2004-2007)
North stream (2009-2012)
SINTEF is responsible for all
welding procedure Strategy:
development and Qualify MIG and TIG welding
qualifications for pipeline
tie-ins and repair welding
for the operators on the
Norwegian shelf.
Materials and Chemistry 4
5. Nord Stream: Sub-sea gas pipeline from Russia to Germany
under construction
1200 km
Two lines in parallel
48”, ID 1153 mm, X70
WT 26.8 – 41.0 mm
Max. sea depth: 210 m
Design pressure:
Up to 220 bar
Two hyperbaric weld
tie-ins:146 and 76msw.
Line I: June 2011
Line II: April 2012
Installation of the first
line started in April
2010
Materials and Chemistry 5
6. The remote PRS welded sleeve concept
Sleeve
Materials and Chemistry 6
7. Nord Stream Hyperbaric Welding Procedures -
Development/qualification
Materials and Chemistry 7
8. Hydrogen pick up
If moisture is present in the hyperbaric weld chamber it
can cause hydrogen pick up during welding, which gives a
risk of cold cracking in the weld and heat affected zone.
A possible hydrogen source during service is hydrogen
evolution and absorbtion due to cathodic protection.
”Cold cracking in hyperbaric welds: A critical combination of residual
stress after welding, applied load, a sensitive microstructure and
hydrogen from welding and/or CP”
Materials and Chemistry 8
9. The model
The cohesive element is
Described by an energy criterion, the traction separation law, TSL
A traction separation law (TSL) is a
function described by the cohesive
stress, σ, and separation, δ.
The area below the curve
represents the critical separation
energy, Гc.
Embedded in a continuum element model
Materials and Chemistry 9
10. Energy reduction due to hydrogen
Estimation of the cohesive energy (Γc) without hydrogen influence
σθ
= 1 − 1.0467θ + 0.1687θ 2
σc
Yiang & Carter, 2004
C
θ=
C + exp(−∆g 0 / RT )
b
Materials and Chemistry 10
11. Estimation of initial cohesive energy
J-r SENT testing in air at 4°C 9
Γc = σ c δ c
16
Measured streching
zone width
prior to ductile
fracture (~0.1mm)
Materials and Chemistry 11
12. Stress and diffusion
Elastic plastic
Mises material model (ABAQUS 6.9)
Material specific stress strain curves
E=205000 MPa, Poisson’s rate= 0.3
Fick’s law
With influence of hydrostatic stress (ABAQUS 6.9):
∂C V
H
V
H
= D∇ C + D ⋅
2
∇C ⋅∇p + D ⋅ C∇ 2 p
∂t (
R⋅ T −T Z ) R ⋅ T −T Z ( )
Trapping
Hydrogen concentration is corrected with respect to plastic strain
within the cohesive element formulation.
Materials and Chemistry 12
13. Experiments
C Mn Si P S Cu Mo Ni Cr Ti Pcm
X70 0.047 1.74 0.10 0.01 7 0.32 0.04 0.25 0.05 0.01 0.16
(CGHAZ) ppm
X70 0.09 1.71 0.30 0.01 10 0.02 0.05 0.07 0.02 0.20
(BM) ppm
BM CGHAZ
Upper
bainite
Martensite
Pearlite UB M
Ferrite
10µm
10µm
Rp 0.2=485 MPa Rp 0.2=810 MPa
Materials and Chemistry 13
14. Testing
•SENT samples, pre charged
at 80°C and -1050mVSCE (1.5
ppm)
•Constant load testing at 4°C
and -1050mVSCE
Fracture
Materials and Chemistry 14
15. FE model geometry
Crack
tip
Element size: 15-20 μm close
to the crack tip to ensure sufficient
resolution of the local stress field.
Materials and Chemistry 15
16. Net section stress and cohesive
parameters
BM CGHAZ
625 Mpa~1.3σRp0.2 550 Mpa~0.7σRp0.2
δc = 0.3 mm, σc = 1700 MPa δc = 0.3 mm and σc = 3900 MPa
Materials and Chemistry 16
17. Application of the model for simulation of cold
cracking in pipe after welding Distribution of hydrogen
Residual stress distribution after welding concentration
WeldSimS
Materials and Chemistry 17
18. Cohesive simulation of crack
susceptability in weld toe
Material:
CGHAZ material and
diffusion properties
(Rp0.2=809 MPa, E=208000 MPa,
ν=0.3, D=3.4 ×10-6 mm2/s)
Load:
10 ppm H in weld, cooling down
to RT, storage for 24 hrs, tensile
loading at 500 and 600 MPa for 1 year
at subsea conditions (1.5 ppm H
at surface)
Materials and Chemistry 18
19. With 30 μm surface ”crack”
No cracking
when loaded at 600 MPa for
1 year
Materials and Chemistry 19
20. Conclusions
The tested base metal X70 steel revealed low sensitivity to hydrogen
embrittlement. Did not fail at net section stresses lower than 1.29
times the 0.2% yield strength.
Weld simulated coarse grained heat affected zone is prone to fracture
at stresses above 70% of the yield strength, which indicates hydrogen
embrittlement susceptibility.
A polynomial traction separation law with intrinsic hydrogen
dependant energy works well for the cohesive FE simulations.
Cohesive parameters best fitting the experiments for base metal:
δc=0.3 mm and σc=1700 MPa (3.5∙σy)
Cohesive parameters applied for CGHAZ: δc=0.3mm and σc=3900
MPa (4.8∙σy).
An example is given proving that the model, given the correct input,
can be applied in evaluating the fracture integrity of a welded joint.
Materials and Chemistry 20
21. Acknowledgements
The present work was financed by the Research Council of Norway
(Petromaks project 192967/S60), Statoil, Technip and EFD Induction.
Materials and Chemistry 21
22. WeldsimS
WeldsimS is a finite element code
developed by IFE and SINTEF for simulating
welding of steels.
Features include:
Phase transformations
Thermal expansion
Transformation plasticity
Flow stress as a function of temperature,
strain rate, and deformation.
Input:
Geometry, material data, welding parameters,
H concentration in weld pool
Output:
Temperature, residual stress/strain,
hardness, phase composition, H distribution
Materials and Chemistry 22