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Effects Of Temperature On Aqueous Freeform Extrusion Fabrication, Jie Li, Ming-Chuan Leu, Greg Hilmas Aug 2015

Effects Of Temperature On Aqueous Freeform Extrusion Fabrication, Jie Li, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An experimental study was conducted to investigate the effect of temperature on ceramic parts produced by paste extrusion based additive manufacturing followed by sintering. A computer-controlled gantry system equipped with a piston extruder was used to extrude aqueous alumina paste. The system includes a temperature control subsystem that allows for freeform extrusion fabrication inside a low-temperature (<0°C) chamber. It can also be used for fabricating parts on a hot plate at ambient or higher temperatures (≥20°C). Test specimens were fabricated from aqueous aluminum pastes at -20°C in the low-temperature chamber and also on the hot plate at 40°C. The minimum angles achievable by these two processes for part fabrication, without use of support material, were compared. Also compared were the relative density and mechanical properties of the parts obtained after sintering. Microstructures were examined via scanning electron microscopy in order to obtain a deeper understanding of the effect of fabrication temperature.

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Laser Metal Deposition Of Functionally Gradient Materials From Elemental Copper And Nickel Powders, Sreekar Karnati, Todd E. Sparks, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, William J. Seufzer Aug 2015

Laser Metal Deposition Of Functionally Gradient Materials From Elemental Copper And Nickel Powders, Sreekar Karnati, Todd E. Sparks, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, William J. Seufzer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This work deals with the planning and fabrication of a functionally gradient copper-nickel composition via Laser Metal Deposition (LMD). Various compositions of copper and nickel were made by blending different weight percentages which were then sequentially deposited to fabricate functionally gradient copper-nickel thin-wall structures. Analyses were performed by sectioning the thin-wall samples for metallographic, hardness, X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) studies. The fabrication was studied for identifying and corroborating the deposited compositions and their corresponding gradients. XRD analyses were performed to identify the crystal structure of the deposit. EDS analysis was instrumental in identifying the variation …

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Parameter Determination And Experimental Validation Of A Wire Feed Additive Manufacturing Model, Kannan Suresh Kumar, Todd E. Sparks, Frank W. Liou Aug 2015

Parameter Determination And Experimental Validation Of A Wire Feed Additive Manufacturing Model, Kannan Suresh Kumar, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser metal deposition with wire feed is one of the additive manufacturing methods with great scope and robustness. Process parameters plays an important role in controlling the process and obtaining an ideal manufactured part. Simulations tools are highly essential in determining the ideal parameters and melt pool conditions. The current work is a transient 3D model of wire feed additive manufacturing which realizes the heat transfer and fluid flow behavior of the process with varying laser power and power density. The model was programmed in Python and a 1 KW Gaussian beam fiber laser was used to conduct experiments. The …

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Optimal Rastering Orientation In Freeform Extrusion Fabrication Processes, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers Aug 2015

Optimal Rastering Orientation In Freeform Extrusion Fabrication Processes, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Many researchers have tried to optimize the build direction of additively manufactured parts to minimize the vertical staircase effect. However, the horizontal staircase effect should also be considered when fully dense parts are to be fabricated. In this paper, part inaccuracy due to the horizontal staircase effect is considered in order to determine the optimal rastering orientation in building the part. An algorithm is developed to estimate this inaccuracy and a technique is proposed to minimize it. The effect of rastering orientation on staircase errors is examined, and the particle swarm optimization method is used to determine the optimum rastering …

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Performance Metric For Powder Feeder Systems In Additive Manufacturing, Venkata Sivaram Bitragunta, Todd E. Sparks, Frank W. Liou Aug 2015

Performance Metric For Powder Feeder Systems In Additive Manufacturing, Venkata Sivaram Bitragunta, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In blown powder Direct Metal Deposition (DMD) process, parts are built by adding metal powder on the melt pool created by the laser system. At low feed rates powder feeder systems have perturbations. The study focused on relationship between the perturbation frequencies by inherent powder feeder designs and its impact on deposition quality. Performance metric determine the relation between perturbations in the powder flow and quality of the deposit. To determine performance metric, various powder feeder designs were analyzed. Perturbation frequencies were introduced to the disk feeder design. The quality of the deposit was determined by the surface roughness of …

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Modeling Of Powder Bed Processing -- A Review, Aaron Flood, Frank W. Liou Aug 2015

Modeling Of Powder Bed Processing -- A Review, Aaron Flood, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Many models have been developed to model powder beds and these methods can be implemented to model a powder bed for Selective Laser Sintering, Selective Laser Melting and any other technique of additive manufacturing which uses powder beds. Two of the main systems are the Discrete Element Method (DEM) and the Geometric Method. The purpose of this paper is to analyze each of the methods. It will first highlight how each of the models creates the powder bed. The next aspect reviewed is the computational time and its causes. And lastly, each of the methods will be examined for their …

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Methods Of Extrusion On Demand For High Solids Loading Ceramic Paste In Freeform Extrusion Fabrication, Wenbin Li, Amir Ghazanfari, Ming-Chuan Leu, Robert G. Landers Aug 2015

Methods Of Extrusion On Demand For High Solids Loading Ceramic Paste In Freeform Extrusion Fabrication, Wenbin Li, Amir Ghazanfari, Ming-Chuan Leu, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Fabrication of highly dense parts with complex geometry by paste-extrusion-based solid freeform fabrication processes requires a precise control of the extrusion flow rate to dispense material on demand, which is often referred as Extrusion-On-Demand (EOD). The extrusion process for aqueous ceramic pastes is complex and difficult to control due to their non-Newtonian behavior, compressibility and inhomogeneity. In this study, three methods of EOD (based on ram extruder, needle valve, and auger valve) are introduced and investigated for the extrusion of high solids loading (i.e., > 50%, volumetric) aqueous alumina paste. Optimal extrusion process parameters for these methods are determined through printing …

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Depth Of Cut Monitoring For Hybrid Manufacturing Using Acoustic Emission Sensor, Haythem Gaja, Frank W. Liou Aug 2015

Depth Of Cut Monitoring For Hybrid Manufacturing Using Acoustic Emission Sensor, Haythem Gaja, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser Metal Deposition LMD is a hybrid manufacturing process consist of a laser deposition system combined with a 5-axis CNC milling system. During laser deposition many parameters and their interaction affect the dimensional accuracy of the part produced, powder flow rate, laser power and travel speed are some of these parameters. Sensing the acoustic emission during milling marching gives feedback information regarding depth of metal being cut subsequent part dimensions, if an error in dimensions is found certain actions, such as remaching, close loop control, or laser remelting can be carried out to correct it. Thus a reliable hybrid manufacturing …

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Planning Freeform Extrusion Fabrication Processes With Consideration Of Horizontal Staircase Effect, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers Aug 2015

Planning Freeform Extrusion Fabrication Processes With Consideration Of Horizontal Staircase Effect, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An algorithm has been developed to estimate the “horizontal” staircase effect and a technique is proposed to reduce this type of geometrical error for freeform extrusion fabrication processes of 3D “solid” parts. The adaptive rastering technique, proposed in this paper, analyzes the geometry of each layer and changes the width of each line of the raster adaptively in order to reduce the staircase error and increase the productivity simultaneously. For each line, the maximum width that results in a staircase error smaller than a predefined threshold is determined for decreasing the fabrication time or increasing the dimensional accuracy, or both. …

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Direct Laser Deposition Of Ti-6al-4v From Elemental Powder Blends, Lei Yan, Xueyang Chen, Wei Li, Frank W. Liou, Joseph William Newkirk Aug 2015

Direct Laser Deposition Of Ti-6al-4v From Elemental Powder Blends, Lei Yan, Xueyang Chen, Wei Li, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A thin-wall structure composed of Ti-6Al-4V has been deposited using direct laser deposition (DLD) from blended Ti, Al, and V elemental powders. The microstructure and composition distribution along the build height direction were intensively investigated using optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and Vickers hardness testing. The microstructures of the as-deposited Ti-xAl-yV were studied using EDS to determine appropriate weight percentage for Al and V in the blended powders before mixing. The effects of laser power and laser transverse speed on the microstructure were investigated and optimized laser processing parameters were concluded.

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A Framework For Large Scale Fused Pellet Modeling (Fpm) By An Industry Robot, Zhiyuan Wang, Renwei Liu, Todd E. Sparks, Frank W. Liou Aug 2015

A Framework For Large Scale Fused Pellet Modeling (Fpm) By An Industry Robot, Zhiyuan Wang, Renwei Liu, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Fused pellet modeling (FPM) is an important method in additive manufacturing technology, where granular material is used instead of filaments. In FPM, prototypes are constructed by the sequential deposition of material layers. As the size of the part increases, the problem of long build times and part deformation becomes critical. In this paper, methods for eliminating the void density during deposition and accuracy control principles for large scale FPM processes are studied. By analyzing the ab initio principles of this process, a mini extruder with variable pitch and progressive diameter screw for the large scale fused deposition is proposed. Based …

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Solid Freeform Fabrication Of Transparent Fused Quartz Using A Filament Fed Process, J. Luo, L. J. Gilbert, C. Qu, B. Morrow, Douglas A. Bristow, Robert G. Landers, J. Goldstein, A. Urbas, Edward C. Kinzel Aug 2015

Solid Freeform Fabrication Of Transparent Fused Quartz Using A Filament Fed Process, J. Luo, L. J. Gilbert, C. Qu, B. Morrow, Douglas A. Bristow, Robert G. Landers, J. Goldstein, A. Urbas, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Glass is a critical material for many scientific and engineering applications including optics, communications, electronics, and hermetic seals. Despite this technological relevance, there has been minimal research toward Additive Manufacturing (AM) of glass, particularly optically transparent glass. Additive Manufacturing of transparent glass offers potential advantages for lower processing costs for small production volumes, increased design freedom, and the ability to locally vary the optical properties of the part. Compared to common soda lime glass, fused quartz is better for AM since it has lower thermal expansion and higher index homogeneity. This paper presents a study of additive manufacturing of transparent …

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Dc-Gain Layer-To-Layer Stability Criterion In Laser Metal Deposition Processes, Patrick M. Sammons, Douglas A. Bristow, Robert G. Landers Aug 2015

Dc-Gain Layer-To-Layer Stability Criterion In Laser Metal Deposition Processes, Patrick M. Sammons, Douglas A. Bristow, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In Laser Metal Deposition (LMD), a blown powder metal additive manufacturing process, functional metal parts are fabricated in a layer-by-layer fashion. In addition to the in-layer dynamics, which describe how the process evolves within a given layer, the additive-fabrication property of LMD creates a second set of dynamics which describe how the process evolves from layer-to-layer. While these dynamics, termed layer-to-layer dynamics, are coupled with both the in-layer dynamics and the process operating conditions, they are not widely considered in the modeling, process planning, or process control of LMD operations. Because of this, seemingly valid choices for process parameters can …

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Freeform Extrusion Fabrication Of Titanium Fiber Reinforced Bioactive Glass Scaffolds, Albin Thomas, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas Aug 2015

Freeform Extrusion Fabrication Of Titanium Fiber Reinforced Bioactive Glass Scaffolds, Albin Thomas, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although implants made with bioactive glass have shown promising results for bone repair, their application in repairing load-bearing long bones is limited due to their low fracture toughness and fairly fast degradation response in vivo. In this paper, we describe our investigation of freeform extrusion fabrication of silicate based 13-93 bioactive glass scaffolds reinforced with titanium fibers. A composite paste was prepared with 13-93 bioactive glass filled with titanium fibers (~16 µm in diameter and aspect ratio of ~250) having a volume fraction of 0.4 vol. %. This paste was then extruded to fabricate scaffolds with an extrudate diameter …

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A Microstructure And Hardness Study Of Functionally Graded Materials Ti6al4v/Tic By Laser Metal Deposition, Jingwei Zhang, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, William J. Seufzer Aug 2015

A Microstructure And Hardness Study Of Functionally Graded Materials Ti6al4v/Tic By Laser Metal Deposition, Jingwei Zhang, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, William J. Seufzer

Materials Science and Engineering Faculty Research & Creative Works

Crack free functionally graded material (FGM) Ti6Al4V-TiC has been fabricated by laser metal deposition (LMD) using TiC and Ti6Al4V powder which were premixed for different ratios. This study focuses on the influence of laser processing parameters and TiC compositional distribution on microstructure, Vickers hardness and phase. The microstructure is analyzed by scanning electron microscopy (SEM), x-ray diffraction (XRD) and hardness tests. Primary carbide, eutectic carbide and unmelted carbide are found in the deposit area. When laser power increased, the primary and secondary dendrite arm spacing increased. The laser power and scanning speed did not influence the Vickers hardness distribution significantly.

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Chemoselective Transfer Hydrogenation Of Nitroarenes Catalyzed By Highly Dispersed, Supported Nickel Nanoparticles, Chengjun Jiang, Zeyu Shang, Xinhua Liang Aug 2015

Chemoselective Transfer Hydrogenation Of Nitroarenes Catalyzed By Highly Dispersed, Supported Nickel Nanoparticles, Chengjun Jiang, Zeyu Shang, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

A recyclable highly dispersed Ni/SiO2 catalyst was prepared by atomic layer deposition. Chemo selective reduction of nitroarenes was studied using the prepared Ni/SiO2 as the catalyst and hydrazine hydrate as a hydrogen donor. Different kinds of nitroarenes were converted to the corresponding anilines with high yields. The high activity of the catalysts could be a result of the highly dispersed Ni nanoparticles. (Chemical Presented).

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4h-Sic Electrostatic Cantilever Actuator Released By Photoelectrochemical Etching And Application For Frequency Mixing, F. Zhao, A. Lim, Q. Tran, C. F. Huang Aug 2015

4h-Sic Electrostatic Cantilever Actuator Released By Photoelectrochemical Etching And Application For Frequency Mixing, F. Zhao, A. Lim, Q. Tran, C. F. Huang

Electrical and Computer Engineering Faculty Research & Creative Works

This paper reports an electrostatically actuated single crystal 4H-SiC cantilever performing frequency mixing. In order to achieve electrostatic actuation and solve the challenge of releasing MEMS structures due to the extreme chemical hardness of 4H-SiC, an n-p-n homoepitaxial structure was chosen, with cantilever actuators released by photoelectrochemical (PEC) etching. The middle p-SiC layer acts as a sacrificial layer in PEC etching to release actuators and also isolates the top n-SiC cantilever from the bottom n-SiC substrate to realize electrostatic actuation. This study shows that electrostatically actuated RF MEMS capable of operating in harsh environments are attainable by single crystal 4H-SiC …

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An Improved Variable Step-Size Zero-Point Attracting Projection Algorithm, Jianming Liu, Steven L. Grant Aug 2015

An Improved Variable Step-Size Zero-Point Attracting Projection Algorithm, Jianming Liu, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes an improved variable step-size (VSS) scheme for zero-point attracting projection (ZAP) algorithm. The proposed VSS is proportional to the sparseness difference between filter coefficients and the true impulse response. Meanwhile, it works for both sparse and non-sparse system identification, and simulation results demonstrate that the proposed algorithm could provide both faster convergence rate and better tracking ability than previous ones.

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Work In Progress -- Does A Technology-Rich Transportation Engineering Experiences Increase Interest In Civil Engineering, Marissa K. Orr, Sanjay Tewari, David E. Hall, Norman D. Pumphrey Aug 2015

Work In Progress -- Does A Technology-Rich Transportation Engineering Experiences Increase Interest In Civil Engineering, Marissa K. Orr, Sanjay Tewari, David E. Hall, Norman D. Pumphrey

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper examines whether a technology-rich transportation engineering experience generates interest among college freshman students towards transportation related degrees and careers, specifically, whether it increases interest in civil engineering. Louisiana Tech’s first-year engineering experience provides relevant, project-focused education for over 500 students each year and an opportunity to introduce transportation-related projects. The six semester-hour, three-course sequence, called “Living with the Lab,” boosts experiential learning through student ownership of inexpensive laboratory equipment. In one section of the Living with the Lab course, a transportation engineer visited the class and the students were led through a technology-rich transportation engineering activity. They used …

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The Fast Contour Deformation Method For Calculating The High Frequency Scattered Field From The Fock Current On The Convex Scatterer, Yu Mao Wu, Weng Cho Chew, Li (Lijun) Jun Jiang Aug 2015

The Fast Contour Deformation Method For Calculating The High Frequency Scattered Field From The Fock Current On The Convex Scatterer, Yu Mao Wu, Weng Cho Chew, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the Fock current from the 3-D convex cylinder is considered. By using the incremental length diffraction coefficient technique (ILDC), the resultant high frequency scattered fields are expressed in terms of the Fock current from convex scatterer. To efficiently solve the scattered fields, we propose the efficient NSDP method. Numerical examples from the convex cylinder scatterer illustrate that the proposed NSDP method for calculating the high frequency scattered fields could achieve the frequency independent computational workload and error controllable accuracy.

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Fast Data Pattern Based Electromagnetic Interference Evaluation For Ic Packaging, Nick K.H. Huang, Li (Lijun) Jun Jiang Aug 2015

Fast Data Pattern Based Electromagnetic Interference Evaluation For Ic Packaging, Nick K.H. Huang, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic interference (EMI) is becoming more serious when the data rate of the digital system continues increasing. However, its modeling and analysis are very challenging. In this paper, a novel electromagnetic superposition method is developed to model the IC packaging electromagnetic emission. It employs the equivalence principle to obtain the electromagnetic field response over a broad spectrum. Then it uses the linear property of the passive parasitic system to superpose the contribution of different signals on the packaging. As a result, with certain pre-calculations, it is convenient to compute the electromagnetic emission efficiently from different signals with various data pattern …

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Fall 2015 E-Certi Newsletter, Center For Educational Research And Teaching Innovation Aug 2015

Fall 2015 E-Certi Newsletter, Center For Educational Research And Teaching Innovation

CAFE Faculty Newsletters

Hello S&T Instructors - It’s the start of another academic year with new challenges and opportunities, including a record number of incoming students. In this issue we feature some innovative and award-winning instructors, including Joel Burken, Theresa Swift and Greg Story. Also find information about the upcoming Curators’ Teaching Summit and learn about projects that have been funded where S&T instructors will be examining and assessing best teaching practices.

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Uncertainty Quantification For Electromagnetic Systems Using Asgc And Dgtd Method, Ping Li, Li (Lijun) Jun Jiang Aug 2015

Uncertainty Quantification For Electromagnetic Systems Using Asgc And Dgtd Method, Ping Li, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an adaptive hierarchical sparse grid collocation (ASGC) method combined with the discontinuous Galerkin time-domain method is leveraged to quantify the impacts of random parameters on the electromagnetics systems. The ASGC method approximates the stochastic observables of interest using interpolation functions over a set of collocation points determined by the Smolyak's algorithm integrated with an adaptive strategy. Instead of resorting to a full-tensor product sense, the Smolyak's algorithm constructs the collocation points in a hierarchical scheme with the interpolation level. Enhanced by an adaptive strategy, the Smolyak's algorithm will sample more points along important dimensions with sharp variations …

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Anharmonic Properties In Mg₂X (X= C, Si, Ge, Sn, Pb) From First-Principles Calculations, Aleksandr V. Chernatynskiy, Simon R. Phillpot Aug 2015

Anharmonic Properties In Mg₂X (X= C, Si, Ge, Sn, Pb) From First-Principles Calculations, Aleksandr V. Chernatynskiy, Simon R. Phillpot

Physics Faculty Research & Creative Works

Thermal conductivity reduction is one of the potential routes to improve the performance of thermoelectric materials. However, detailed understanding of the thermal transport of many promising materials is still missing. In this paper, we employ electronic-structure calculations at the level of density functional theory to elucidate thermal transport properties of the Mg2X (X=C, Si, Ge, Sn, and Pb) family of compounds, which includes Mg2Si, a material already identified as a potential thermoelectric. All these materials crystallize into the same antifluorite structure. Systematic trends in the anharmonic properties of these materials are presented and examined. Our calculations …

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Silver Nanoparticle Coated Bioactive Glasses - Composites With Dex/Cmc Hydrogels: Characterization, Solubility, And In Vitro Biological Studies, Anthony W. Wren, Pegah Hassanzadeh, Lana M. Placek, Timothy J. Keenan, Aisling Coughlan, Lydia R. Boutelle, Mark R. Towler Aug 2015

Silver Nanoparticle Coated Bioactive Glasses - Composites With Dex/Cmc Hydrogels: Characterization, Solubility, And In Vitro Biological Studies, Anthony W. Wren, Pegah Hassanzadeh, Lana M. Placek, Timothy J. Keenan, Aisling Coughlan, Lydia R. Boutelle, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Silver (Ag) coated bioactive glass particles (Ag-BG) were formulated and compared to uncoated controls (BG) in relation to glass characterization, solubility and microbiology. X-ray diffraction (XRD) confirmed a crystalline AgNP surface coating while ion release studies determined low Ag release (/L). Cell culture studies presented increased cell viability (127 and 102%) with lower liquid extract (50 and 100 ml/ml) concentrations. Antibacterial testing of Ag-BG in E. coli, S. epidermidis and S. aureus significantly reduced bacterial cell viability by 60-90%. Composites of Ag-BG/CMC-Dex Hydrogels were formulated and characterized. Agar diffusion testing was conducted where Ag-BG/hydrogel composites produced the largest inhibition zones …

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Distributive Radiation And Transfer Characterization Based On The Peec Method, Ying S. Cao, Li (Lijun) Jun Jiang, Albert E. Ruehli Aug 2015

Distributive Radiation And Transfer Characterization Based On The Peec Method, Ying S. Cao, Li (Lijun) Jun Jiang, Albert E. Ruehli

Electrical and Computer Engineering Faculty Research & Creative Works

Power radiation and radiated coupling among different structures represent an important area for research study. The partial element equivalent circuit method (PEEC) is a powerful technique which bridges the gap between the electromagnetic and circuit theories. In this paper, we develop a new approach for PEEC to calculate the distributive power radiation and couplings. With this approach, formulations for both the radiated power and the transferred power can be evaluated. Further, the physical meanings of the power results are interpreted according to the conservation of energy law. We use electric dipoles, magnetic dipoles and patch antennas as well as coupled …

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Leveraging Social Capital To Obtain Top Management Support In Complex, Cross-Functional It Projects, Gloria H. W. Liu, Eric T. G. Wang, Cecil Eng Huang Chua Aug 2015

Leveraging Social Capital To Obtain Top Management Support In Complex, Cross-Functional It Projects, Gloria H. W. Liu, Eric T. G. Wang, Cecil Eng Huang Chua

Business and Information Technology Faculty Research & Creative Works

Research argues that a major reason for IT project failure is the lack of top management support. However, obtaining top management support is often considered outside the IT project team's control. In this paper, we investigate how IT project teams can obtain such support. We find that creating and mobilizing social capital through repeated interaction with top managers and their confidants helps a project obtain top management support. Also, a failure to use social capital to engage top management can cause a decrease in their support. We demonstrate these points through a natural experiment of the support of three division …

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Strain Distribution And Crack Detection In Concrete Overlays With Pulse Pre-Pump Brillouin Optical Time Domain Analysis, Yi Bao, Genda Chen Aug 2015

Strain Distribution And Crack Detection In Concrete Overlays With Pulse Pre-Pump Brillouin Optical Time Domain Analysis, Yi Bao, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This report is focused on the measurement of strain distributions and crack detection in unbonded and bonded pavement overlays. The main objectives of this study are: (a) to characterize the strain sensing properties of distributed fiber optic sensors with recently developed pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA), (b) to develop an installation method for real world applications, (c) to document the performance of the PPP-BOTDA technology in unbonded/bonded pavement applications, and (d) to develop a numerical model to facilitate the analysis of mechanical behavior of unbonded pavement overlay under vehicle wheel loads. A thin concrete layer can be …

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Method Of Effective Roughness Dielectric In A Pcb: Measurement And Full-Wave Simulation Verification, Marina Koledintseva, Tracey Vincent, Antonio Ciccomancini Scogna, Scott Hinaga Aug 2015

Method Of Effective Roughness Dielectric In A Pcb: Measurement And Full-Wave Simulation Verification, Marina Koledintseva, Tracey Vincent, Antonio Ciccomancini Scogna, Scott Hinaga

Electrical and Computer Engineering Faculty Research & Creative Works

Surface roughness topography of printed circuit boards (PCBs) needs to be included in signal integrity simulations in order to accurately predict the insertion loss of the structure and its delay time. An effective roughness dielectric (ERD) model can be used to substitute an inhomogeneous interface between copper foil and laminate dielectric in a PCB. Herein, this approach is tested for verification using 3-D full-wave numerical simulations. These ERD layers with the appropriate complex permittivity are included in the modeling of strip line examples. The parameters of an ambient laminate dielectric refined from conductor roughness in the strip line are determined …

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System And Process For Upgrading Hydrocarbons, Dennis N. Bingham, Kerry M. Klingler, Joseph D. Smith, Terry D. Turner, Bruce M. Wilding Aug 2015

System And Process For Upgrading Hydrocarbons, Dennis N. Bingham, Kerry M. Klingler, Joseph D. Smith, Terry D. Turner, Bruce M. Wilding

Chemical and Biochemical Engineering Faculty Research & Creative Works

In one embodiment, a system for upgrading a hydrocarbon material may include a black wax upgrade subsystem and a molten salt gasification (MSG) subsystem. The black wax upgrade subsystem and the MSG subsystem may be located within a common pressure boundary, such as within a pressure vessel. Gaseous materials produced by the MSG subsystem may be used in the process carried out within the black wax upgrade subsystem. For example, hydrogen may pass through a gaseous transfer interface to interact with black wax feed material to hydrogenate such material during a cracking process. In one embodiment, the gaseous transfer interface …

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