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2008

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Articles 1531 - 1560 of 4190

Full-Text Articles in Engineering

Calcium Phosphate Film Coating On Titanium Substrate By Electrochemical Deposition, D P. Kashima, A Rakngarm Jul 2008

Calcium Phosphate Film Coating On Titanium Substrate By Electrochemical Deposition, D P. Kashima, A Rakngarm

Journal of Metals, Materials and Minerals

Calcium phosphate film on titanium substrate was achieved by electrochemical method in four different kinds of electrolyte. The pure titanium metal (99.99%) with 0.8 cm in width and 2 cm in length was used as a substrate and it was subsequently etched by 2M HF for 1 minute before electrochemical deposition. Calcium phosphate film could form at a different current density for each kind of electrolyte as follows: 10 mA/cm2 for MCPM based aqueous solution, 20 mA/cm2 for MCPM based aqueous solution with ions addition, 10 mA/cm2 and 20 mA/cm2 for MCPM based 20%V/V ethanol and 50%V/V ethanol solution, respectively. …

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Improved L-929 Cell Growth From Self Assembled Pdadmac/Gelatin Thin Films, P Kittitheeranun, P Potiyaraj, T Bunaprasert, N Sanchavanakit, S T. Dubas Jul 2008

Improved L-929 Cell Growth From Self Assembled Pdadmac/Gelatin Thin Films, P Kittitheeranun, P Potiyaraj, T Bunaprasert, N Sanchavanakit, S T. Dubas

Journal of Metals, Materials and Minerals

This article demonstrates the advantages of using PDADMAC/gelatin over chitosan/gelatin multilayer thin films to improve L-929 mouse fibroblast growth. Although chitosan-based materials are often preferred in cell culture, we put in evidence the problematic low stability and decomposition of chitosan based film under physiological pH. Two kinds of coating were assembled using either chitosan or Poly(diallyldimethylammonium chloride) (PDADMAC) as polycationic polyelectrolyte and gelatin as the anionic counterpart. The non-toxic nature of each coating was confirmed by MTT assay for cell viability and cell proliferation. Using optical microscopy, it was observed that the L-929 fibroblast spread preferentially on the PDADMAC/gelatin surface …

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Effects Of Tin Powder On Properties Of Sintered Stainless Steels, N Tosangthum, P Muangtong, O Coovattanachai, M Morakotjinda, T Yodkaew, P Wila, R Krataitong, B Vetayanugul, R Tongsri Jul 2008

Effects Of Tin Powder On Properties Of Sintered Stainless Steels, N Tosangthum, P Muangtong, O Coovattanachai, M Morakotjinda, T Yodkaew, P Wila, R Krataitong, B Vetayanugul, R Tongsri

Journal of Metals, Materials and Minerals

It was found that addition of 4 wt.% of gas-atomized tin (Sn) powder to stainless steel powders could alter sintered properties of P/M stainless steels. For stainless steel series 300 powders, Sn powder addition resulted in improved tensile properties and hardness. It was speculated that the liquid Sn, formed during sintering process, acted as either a sintering activator or a solvent for nickel (Ni) dissolution. Sintering activation existed because the liquid Sn acted as a diffusion path for powder particle constituent atoms. Dissolution of Ni in Sn was simply due to diffusion of Ni atoms from stainless steel series 300 …

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Sintered Properties Of 409l Powder Compacts Influenced By Metal Powder Additives, O Coovattanachai, T Yodkaew, M Morakotjinda, N Tosangthum, R Krataitong, A Daraphan, B Vetayanugul, R Tongsri Jul 2008

Sintered Properties Of 409l Powder Compacts Influenced By Metal Powder Additives, O Coovattanachai, T Yodkaew, M Morakotjinda, N Tosangthum, R Krataitong, A Daraphan, B Vetayanugul, R Tongsri

Journal of Metals, Materials and Minerals

Sintering of powder compacts, prepared by admixing of 409L powder with 2-6 wt.% of copper and nickel powders was investigated. It was observed that the strength of the 409L-Cu specimens increased with increasing Cu content. In contrast, sintered density and elongation decreased with increasing Cu content due to swelling effect. When 2 wt.% of Ni powders were added, sintered density and strengths were maximized. When Ni contents higher than 2 wt.% , the decrease of sintered density and strengths were attributed to the number of pores left by the original sites of Ni powder particles.

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Sintered Fe-Al2o3and Fe-Sic Composites, T Yodkaew, M Morakotjinda, N Tosangthum, O Coovattanachai, R Krataitong, P Siriphol, B Vetayanugul, S Chakthin, N Poolthong, R Tongsri Jul 2008

Sintered Fe-Al2o3and Fe-Sic Composites, T Yodkaew, M Morakotjinda, N Tosangthum, O Coovattanachai, R Krataitong, P Siriphol, B Vetayanugul, S Chakthin, N Poolthong, R Tongsri

Journal of Metals, Materials and Minerals

The presence of non-reactive (Al2O3) and reactive (SiC) hard particles affected properties of sintered Fe-base composites. With the same compacting and sintering conditions, addition of Al2O3 particles caused reduction of sintered densities. Tensile strengths, elongation and hardness of the sintered Fe-Al2O3 materials decreased with increasing Al2O3 particle amounts. The presence of Al2O3 particles prohibited compacting and sintering processes of the Fe powder. In contrast, addition of SiC particles resulted in reaction between Fe and SiC particles. Sintered density of the sintered Fe-SiC composites was significantly lower than that of the sintered Fe-Al2O3 materials. However, tensile strengths and hardness, except elongation, …

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Sintered Materials Prepared From Stainless Steel Series 300 And 400 Powders, M Morakotjinda, N Kuljittipipat, N Poolthong, N Tosangthum, P Wila, R Krataitong, T Yodkaew, O Coovattanachai, B Vetayanugul, R Tongsri Jul 2008

Sintered Materials Prepared From Stainless Steel Series 300 And 400 Powders, M Morakotjinda, N Kuljittipipat, N Poolthong, N Tosangthum, P Wila, R Krataitong, T Yodkaew, O Coovattanachai, B Vetayanugul, R Tongsri

Journal of Metals, Materials and Minerals

Some sintered materials were prepared from mixtures of stainless steel series 300 and series 400 powders. The sintered stainless steels consisted of both austenitic and ferritic phases so they were designated as sintered duplex stainless steels (SDSSs). Microstructures and properties of the SDSSs were characterized and tested. Most SDSSs, except the 310L powder-base SDSSs, showed improved tensile strengths and hardness but exhibited inferior ductility, compared to those of the sintered stainless steels series 300. The 304L-410L SDSS showed promising mechanical properties. This SDSS were further investigated by varying weight ratio of 304L and 410L powders. It was found that sintered …

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Multiple Reference Frame-Based Control Of Three-Phase Pwm Boost Rectifiers Under Unbalanced And Distorted Input Conditions, Peng Xiao, Keith Corzine, Ganesh K. Venayagamoorthy Jul 2008

Multiple Reference Frame-Based Control Of Three-Phase Pwm Boost Rectifiers Under Unbalanced And Distorted Input Conditions, Peng Xiao, Keith Corzine, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

Many control algorithms and circuits for three-phase pulse width modulation active rectifiers have been proposed in the past decades. In most of the research, it is often assumed that the input voltages are balanced or contain only fundamental frequency components. In this paper, a selective harmonic compensation method is proposed based on an improved multiple reference frame algorithm, which decouples signals of different frequencies before reference frame transformation. This technique eliminates interactions between the fundamental-frequency positive-sequence components and harmonic and/or negative-sequence components in the input currents, so that fast and accurate regulation of harmonic and unbalanced currents can be achieved. …

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Comparison Of Ultracapacitor Electric Circuit Models, Lisheng Shi, Mariesa Crow Jul 2008

Comparison Of Ultracapacitor Electric Circuit Models, Lisheng Shi, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Due to ultracapacitors' unique features, the electrical performances and reliabilities of electrical systems using ultracapacitors can be improved. It is important to have a good ultracapacitor model for simulation and assisting electrical system design and product development. Several kinds of ultracapacitor models are given these years. Especially, electric circuit models are the interested ones for electrical engineers. This paper concentrates on the electric circuit model. Three basic RC network models are discussed in detail, including modeling ideas, circuit formation, linear/nonlinear factors and evaluations of each model. The general electric circuit model considering the inductance and leakage current effects are given. …

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A Comparison Of Linear And Nonlinear Statcom Control For Power Quality Enhancement, Atousa Yazdani, Mariesa Crow, Jianjun Guo Jul 2008

A Comparison Of Linear And Nonlinear Statcom Control For Power Quality Enhancement, Atousa Yazdani, Mariesa Crow, Jianjun Guo

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces a multilevel STATCOM for electric arc furnace power quality enhancement. An eleven level cascaded multilevel converter is used to alleviate the impacts of an unbalanced arc furnace load. The STATCOM provides a power electronic-based means of embedded control for reactive power support.

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Self-Tuned Projected Cross Point -- An Improved Current-Mode Control Technique, Kai-Tak Wan, Mehdi Ferdowsi Jul 2008

Self-Tuned Projected Cross Point -- An Improved Current-Mode Control Technique, Kai-Tak Wan, Mehdi Ferdowsi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Self-tuned projected cross point control for power electronic converters is introduced. Projected cross point control (PCPC) combines the advantages of both analog and digital current-mode control techniques. Despite several advantages, accuracy of the PCPC method depends on the power stage inductor value. However, ferromagnetic characteristics of the inductor core material make the inductor measurement inaccurate. Furthermore, the inductor value is subject to change due to temperature variations or other environmental effects. To overcome the dependence of the PCPC method on the inductor value, self- tuned PCPC approach is introduced in this paper. Unlike the conventional PCPC scheme, self-tuned PCPC method …

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Application Of Statcom For Improved Reliability Of Power Grid Containing A Wind Turbine, Aditya P. Jayam, Badrul H. Chowdhury, Nikhil Kumar Ardeshna Jul 2008

Application Of Statcom For Improved Reliability Of Power Grid Containing A Wind Turbine, Aditya P. Jayam, Badrul H. Chowdhury, Nikhil Kumar Ardeshna

Electrical and Computer Engineering Faculty Research & Creative Works

Larger wind farms when integrated to the power system pose stability and control issues. This paper investigates the use of a static synchronous compensator (STATCOM) with wind farms for the purpose of stabilizing the grid voltage after a grid-side disturbance viz., a three phase short circuit fault and load changes. The strategy focuses on a fundamental grid operational requirement to maintain proper voltages at the point of common coupling by regulating the voltage at the collector bus of a wind farm. The DC voltage at individual wind turbine (WT) inverters is also stabilized which facilitates the continuous operation of each …

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A Computational Approach To Optimal Damping Controller Design For A Gcsc, Swakshar Ray, Ganesh K. Venayagamoorthy, Edson H. Watanabe Jul 2008

A Computational Approach To Optimal Damping Controller Design For A Gcsc, Swakshar Ray, Ganesh K. Venayagamoorthy, Edson H. Watanabe

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a computational approach for an offline measurement-based design of an optimal damping controller using adaptive critics for a new type of flexible ac transmission system device-the gate-controlled series capacitor (GCSC). Remote measurements are provided to the controller to damp out system modes. The optimal controller is developed based on the heuristic dynamic programming (HDP) approach. Three multilayer-perceptron neural networks are used in the design-the identifier/model network to identify the dynamics of the power system, the critic network to evaluate the performance of the damping controller, and the controller network to provide optimal damping. This measurement-based technique provides …

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A Dstatcom Controller Tuned By Particle Swarm Optimization For An Electric Ship Power System, Pinaki Mitra, Ganesh K. Venayagamoorthy Jul 2008

A Dstatcom Controller Tuned By Particle Swarm Optimization For An Electric Ship Power System, Pinaki Mitra, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

In an all-electric ship power system, the power quality problems mainly arise due to the pulsed loads, which cause the degradation of the overall system performance. The paper proposes the application of DSTATCOM to improve these power quality problems of an electric ship. DSTATCOM is a shunt compensation device, which regulates the bus voltage by injecting reactive power during the pulsed load operations. The control strategy of DSTATCOM plays an important role to meet the objectives. The paper proposes a controller design strategy which is based on particle swarm optimization (PSO). PSO, an algorithm that falls into swarm intelligence family, …

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Live Wire Segmentation Tool For Osteophyte Detection In Lumbar Spine X-Ray Images, Santosh Seetharaman, R. Joe Stanley, Soumya De, Sameer Antani, L. Rodney Long, George R. Thoma Jul 2008

Live Wire Segmentation Tool For Osteophyte Detection In Lumbar Spine X-Ray Images, Santosh Seetharaman, R. Joe Stanley, Soumya De, Sameer Antani, L. Rodney Long, George R. Thoma

Electrical and Computer Engineering Faculty Research & Creative Works

Computer-assisted vertebra segmentation in x-ray images is a challenging problem. Inter-subject variability and the generally poor contrast of digitized radiograph images contribute to the segmentation difficulty. In this paper, a semi-automated live wire approach is investigated for vertebrae segmentation. The live wire approach integrates initially selected user points with dynamic programming to generate a closed vertebra boundary. In order to assess the degree to which vertebra features are conserved using the live wire technique, convex hull-based features to characterize anterior osteophytes in lumbar vertebrae are determined for live wire and manually segmented vertebrae. Anterior osteophyte discrimination was performed over 405 …

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Performance Analysis And Effect Of Multi-User Interference For Ultra Wideband Communications, Mukta Athavale Jul 2008

Performance Analysis And Effect Of Multi-User Interference For Ultra Wideband Communications, Mukta Athavale

Electrical Engineering Theses - Archive

Ultra-Wideband (UWB) is an upcoming technology for short-range high data rate applications like Wireless Personal Area Networks or medium/long-range low data rate applications like sensor networks. UWB has many captivating characteristics such as very short duration pulses (order of nanoseconds), multipath channel, large instantaneous bandwidth and time hopping pulse trains resulting in coexistence with the existing narrow band users. The Ultra Wideband communication systems employ the technique of Impulse radio of transmitting short duration pulses which result in extremely wide bandwidth and many performance benefits. Since UWB systems operate in dense multipath environments, RAKE receiver is the optimum choice for …

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Cs 242: Computer Programming Iii, Guozhu Dong Jul 2008

Cs 242: Computer Programming Iii, Guozhu Dong

Computer Science & Engineering Syllabi

No abstract provided.

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Cs 480/680: Comparative Languages, Krishnaprasad Thirunarayan Jul 2008

Cs 480/680: Comparative Languages, Krishnaprasad Thirunarayan

Computer Science & Engineering Syllabi

This course will introduce fundamental concepts and paradigms underlying the design of modern programming languages. For concreteness, we study the details of an object-oriented language (e.g. Java), and a functional language (e.g., Scheme). The overall goal is to enable comparison and evaluation of existing languages. The programming assignments will be coded in Java 5 and in Scheme.

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Cs 415: Social Implications Of Computing, Leo Finkelstein Jul 2008

Cs 415: Social Implications Of Computing, Leo Finkelstein

Computer Science & Engineering Syllabi

CS 415 is a communication skills course using as its subject matter current salient issues associated with the social implications of computing. In addition to the course text, you will need to use certain reading materials in the library and elsewhere, and you will be responsible for using concepts and theories provided in class lectures and discussions.

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Cs 240: Computer Programming I, Travis E. Doom Jul 2008

Cs 240: Computer Programming I, Travis E. Doom

Computer Science & Engineering Syllabi

Basic concepts of programming and programming languages are introduced. Emphasis is on structured programming and stepwise refinement. Prerequisite: MTH 130 or MPL 5.

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Cs 205-02: Introduction To Computers And Office Productivity Software, John P. Herzog Jul 2008

Cs 205-02: Introduction To Computers And Office Productivity Software, John P. Herzog

Computer Science & Engineering Syllabi

Focus on learning MS Office software applications including word processing (intermediate), spreadsheets, database and presentation graphics using a case study approach where critical thinking and problem solving skills are required. Computer concepts are integrated throughout the course to provide an understanding of the basics of computing, the latest technological advances and how they are used in industry. Ethics and issues encountered in business are discussed to challenge students on societal impact of technology.

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Ceg 720-01: Computer Architecture I, Soon M. Chung Jul 2008

Ceg 720-01: Computer Architecture I, Soon M. Chung

Computer Science & Engineering Syllabi

Review of sequential computer architecture and study of parallel computers. Topics include memory hierarchy, reduced instruction set computer; pipeline processing, multiprocessing, various parallel computers, interconnection networks, and fault-tolerant computing. 3 hours lecture and 2 hours lab.

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Ceg 233-01: Linux And Windows, Bin Wang Jul 2008

Ceg 233-01: Linux And Windows, Bin Wang

Computer Science & Engineering Syllabi

Introduction to Linux and Windows systems. GUI and Windowing Systems. Files and Directories. Ownership and Sharing. Programs and Processes. System calls, Libraries. Loading. Dynamic linking. Command Line Shells. Scripting languages. Regular expressions. Clients and Servers. Web browser clients and HTTPS. System Administration. 4 credit hours. 3 hours labs, 2 hours labs. Prerequisites: None.

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Ceg 460/660-01: Computer Engineering, Eric Maston Jul 2008

Ceg 460/660-01: Computer Engineering, Eric Maston

Computer Science & Engineering Syllabi

This course is concerned with the techniques of designing and constructing large program. Some of the required basic concepts necessarily have to be developed using small programs as examples. To this extent, we also study programming-in-the-small. The overall objectives are to present an overview of issues in the development of software, to discuss terminology, to illustrate via example case studies, and to give sufficiently detailed advice on how to develop quality software. Hands-on experience is emphasized through the use of homework and a class project.

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Ceg 720-01: Computer Architecture, Jack Jean Jul 2008

Ceg 720-01: Computer Architecture, Jack Jean

Computer Science & Engineering Syllabi

No abstract provided.

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Ceg 433/633-01: Operating Systems, Yong Pei Jul 2008

Ceg 433/633-01: Operating Systems, Yong Pei

Computer Science & Engineering Syllabi

This course provides an introduction to operating system design. Topics to be covered include: Operating system structures, Operating system interfaces, Process management and scheduling, Inter-process communication, File systems and Memory management and Device access.

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Ceg 360/560-01: Digital System Design, Travis E. Doom Jul 2008

Ceg 360/560-01: Digital System Design, Travis E. Doom

Computer Science & Engineering Syllabi

Design of digital systems. Topics include flip-flops, registers, counters, programmable logic devices, memory devices, register-level design, and microcomputer system organization. Students must show competency in the design of digital systems. 3 hours lecture, 2 hours lab. Prerequisite: CEG 260.

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Cs 241: Computer Programming Ii, Eric Maston Jul 2008

Cs 241: Computer Programming Ii, Eric Maston

Computer Science & Engineering Syllabi

This is the second course in the Introduction to Computer Programming series. A continuation of CS240. The emphasis is on data abstraction and software development. Prerequisite: CS240.

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Design And Evaluation Of A Low-Tension Cable Guardrail End Terminal System, Rebecca A. Hitz, Kirk J. Molacek, Cody S. Stolle, Karla A. Polivka, Ronald K. Faller, John R. Rohde, Dean L. Sicking, John D. Reid Jul 2008

Design And Evaluation Of A Low-Tension Cable Guardrail End Terminal System, Rebecca A. Hitz, Kirk J. Molacek, Cody S. Stolle, Karla A. Polivka, Ronald K. Faller, John R. Rohde, Dean L. Sicking, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

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Implementation Of Conductive Concrete For Deicing (Roca Bridge), Christopher Y. Tuan Jul 2008

Implementation Of Conductive Concrete For Deicing (Roca Bridge), Christopher Y. Tuan

Nebraska Department of Transportation: Research Reports

No abstract provided.

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Design Evaluation Of A Low-Tension Cable Guardrail End Terminal System, Cody S. Stolle, Karla A. Polivka, Ronald K. Faller, John R. Rohde, Dean L. Sicking, Rebecca A. Hitz, Kirk J. Molacek, John D. Reid Jul 2008

Design Evaluation Of A Low-Tension Cable Guardrail End Terminal System, Cody S. Stolle, Karla A. Polivka, Ronald K. Faller, John R. Rohde, Dean L. Sicking, Rebecca A. Hitz, Kirk J. Molacek, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

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