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2002

Missouri University of Science and Technology

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Articles 1 - 30 of 144

Full-Text Articles in Engineering

Interactive Learning Tools: Animating Statics, Nancy Hubing, David B. Oglesby, Timothy A. Philpot, Vikas Yellamraju, Richard H. Hall, Ralph E. Flori Dec 2002

Interactive Learning Tools: Animating Statics, Nancy Hubing, David B. Oglesby, Timothy A. Philpot, Vikas Yellamraju, Richard H. Hall, Ralph E. Flori

Business and Information Technology Faculty Research & Creative Works

Computer-Based Modules for Engineering Instruction Must Be Concise, Flexible, Educational and Engaging in Order to Effectively Supplement Traditional Classroom Teaching Tools. a Computer Example that Takes More Time Than a Chalkboard Presentation is Not Likely to Be Useful in Today's Engineering Classroom. Flexible Navigation is Necessary So that the Instructor Can Quickly and Easily Respond to Student Questions. Useful Modules Must Also Improve Problem-Solving Skills or Clarify Troublesome Concepts in Order to Be Considered Worthy of Inclusion in the Limited Class Time Available. Finally, and Perhaps Most Importantly, Effective Computer-Based Modules Must Meet the Challenge of Holding the Student's Attention. …

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Electrical Properties Of Srbi₂Ta₂O₉ Ferroelectric Thin Films At Low Temperature, Pingxiong Yang, David L. Carroll, John Ballato, Robert W. Schwartz Dec 2002

Electrical Properties Of Srbi₂Ta₂O₉ Ferroelectric Thin Films At Low Temperature, Pingxiong Yang, David L. Carroll, John Ballato, Robert W. Schwartz

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The temperature dependence of electrical properties for SrBi2Ta2O9 thin film capacitors with platinum electrodes (Pt/SBT/Pt) on silicon wafers was studied from 10 to 300 K. with a decrease in temperature from 300 to 200 K, the remanent polarization of the thin films shows about an 11% reduction from its 300 K value; however, it is reduced by about 87% reduction from its 200 K value when the temperature drops from 200 to 100 K. with a decrease to 200 K, the polarization fatigue was significant, and the capacitor shows an approximate 29% reduction in polarization from its initial value following …

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Dynamic Yield Analysis And Enhancement Of Fpga Reconfigurable Memory Systems, Minsu Choi, Nohpill Park Dec 2002

Dynamic Yield Analysis And Enhancement Of Fpga Reconfigurable Memory Systems, Minsu Choi, Nohpill Park

Electrical and Computer Engineering Faculty Research & Creative Works

This paper addresses the issues of field programmable gate arrays (FPGA) reconfigurable memory systems with faulty physical memory cells and proposes yield measurement techniques. Static yield (i.e., the yield which does not take into account the inherited redundancy utilization for repair) and dynamic yield (i.e., the yield which takes into account the inherited redundancy utilization for repair) of FPGA reconfigurable memory systems and their characteristics are extensively analyzed. Yield enhancement of conventional memory systems relies on additional redundancy, but FPGA reconfigurable memory systems have inherited redundancy and customizability. Thus, they can accommodate numerous target memory configurations, and redundant memory cells, …

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Segmented Roll For Casting Metal Strip, James R. Sauer, Ronald J. O'Malley, Robert S. Williams Nov 2002

Segmented Roll For Casting Metal Strip, James R. Sauer, Ronald J. O'Malley, Robert S. Williams

Materials Science and Engineering Faculty Research & Creative Works

Casting molten metal using a segmented roll for casting continuous metal strip. A strip caster (10) for producing a continuous strip (18) includes a tundish for containing a melt and a pair of horizontally disposed water cooled composite casting rolls (84). The casting rolls are juxtaposed relative to one another for forming a pouring basin (16) for receiving molten metal. The composite rolls are formed from a plurality of annular segments (45). Each segment preferably includes at least a pair of coolant openings (34) and means for aligning the coolant openings, such as a pair of alignment openings (26). The …

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Numerical Simulation Of Partial Discharge Propagation In Cable Joints Using The Finite Difference Time Domain Method, David Pommerenke, R. Jobava, R. Heinrich Nov 2002

Numerical Simulation Of Partial Discharge Propagation In Cable Joints Using The Finite Difference Time Domain Method, David Pommerenke, R. Jobava, R. Heinrich

Electrical and Computer Engineering Faculty Research & Creative Works

In this second of a series of three papers, the authors investigate partial discharge (PD) detection and propagation in cable joints. The complex nature of cable joints leads to errors when PD analysis is carried out using conventional equivalent circuits. The authors use the finite difference time domain method to determine the transient electromagnetic fields caused by simulated PD in model cable joints.

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Photoreflectance Spectroscopy Of Strained (In)Gaasn/Gaas Multiple Quantum Wells, J. B. Heroux, Xiaodong Yang, W. I. Wang Oct 2002

Photoreflectance Spectroscopy Of Strained (In)Gaasn/Gaas Multiple Quantum Wells, J. B. Heroux, Xiaodong Yang, W. I. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The effect of a variation of the indium and nitrogen concentrations in Inᵪ Ga1-x As1-y Ny /GaAs multiquantum wells grown by molecular beam epitaxy is studied systematically by room temperature photoreflectance spectroscopy. The band gap redshift caused by a nitrogen fraction of 1.5% decreases by as much as 30% as the indium fraction increases from 0% to 20%. A moderate increase of electron effective mass (Δmₑ ~ 0.03m₀) is found in all samples containing nitrogen (y ≳ 1%). In compressively strained quantum wells, the energy separation between the first confined heavy and light hole energy levels decreases …

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Standard Test Method For Determining The Web Crippling Strength Of Cold-Formed Steel Members, Roger A. Laboube, R. Schuster Oct 2002

Standard Test Method For Determining The Web Crippling Strength Of Cold-Formed Steel Members, Roger A. Laboube, R. Schuster

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

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Standard Test Method For Determining The Web Crippling Strength Of Cold-Formed Steel Members, R. M. Schuster, Roger A. Laboube Oct 2002

Standard Test Method For Determining The Web Crippling Strength Of Cold-Formed Steel Members, R. M. Schuster, Roger A. Laboube

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

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Metrics-Based Framework For Decision Making In Cots-Based Software Systems, Sahra Sedigh, Arif Ghafoor, Raymond A. Paul Oct 2002

Metrics-Based Framework For Decision Making In Cots-Based Software Systems, Sahra Sedigh, Arif Ghafoor, Raymond A. Paul

Electrical and Computer Engineering Faculty Research & Creative Works

The growing reliance on Commercial-Off-The-Shelf (COTS) components for developing large-scale projects introduces a new paradigm in software Engineering; which requires the design of new software development and business processes. Large scale component reuse leads to savings in development resources, enabling these resources to be applied to areas such as quality improvement. These savings come at the price of integration difficulties, performance constraints, and incompatibility of components from multiple vendors. Relying on COTS components also increases the system's vulnerability to risks arising from third-party development, which can negatively affect the quality of the system, as well as causing expenses not incurred …

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Application Of Maxwell Solvers To Pd Propagation. I. Concepts And Codes, David Pommerenke, S. Sakaguchi Oct 2002

Application Of Maxwell Solvers To Pd Propagation. I. Concepts And Codes, David Pommerenke, S. Sakaguchi

Electrical and Computer Engineering Faculty Research & Creative Works

This article reviews the basic approaches to solving electromagnetic propagation in the context of PD detection. It also investigates available commercial software, introduces the steps required to obtain trustworthy computational results, and gives an example of detailed analysis of PD propagation.

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Magnetic Order In Yba₂Cu₃O₆₊ₓ Superconductors, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Jeffrey W. Lynn, Seunghun Lee, Fatih Dogan Oct 2002

Magnetic Order In Yba₂Cu₃O₆₊ₓ Superconductors, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Jeffrey W. Lynn, Seunghun Lee, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Polarized and unpolarized neutron diffraction has been used to search for magnetic order in YBa2Cu3O6+x superconductors. Most of the measurements were made on a high quality crystal of YBa2CU3O6.6. It is shown that this crystal has highly ordered ortho-II chain order, and a sharp superconducting transition. Inelastic scattering measurements display a very clean spin-gap and pseudogap with any intensity at 10 meV being 50 times smaller than the resonance intensity. The crystal shows a complicated magnetic order that appears to have three components. A magnetic phase is found at …

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Introducing Molecular Biology To Environmental Engineers: Through Development Of A New Course, Daniel B. Oerther Sep 2002

Introducing Molecular Biology To Environmental Engineers: Through Development Of A New Course, Daniel B. Oerther

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The introduction of a course "Molecular Methods in Environmental Engineering" is discussed. The course is developed to address the growing national need for integrating geonomics and molecular biology into the engineering curriculum. Fifteen graduate students were successfully introduced to molecular biology through lectures and hands-on laboratory excercises following the "full-cycle 165 rRNA approach". The course helps in providing supportive and independent learning environment to the students.

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Four-Terminal Quantum Resistor Network For Electron-Wave Computing, Diwakar Ramamurthy, Cheng-Hsiao Wu Sep 2002

Four-Terminal Quantum Resistor Network For Electron-Wave Computing, Diwakar Ramamurthy, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

Interconnected ultrathin conducting wires or, equivalently, interconnected quasi-one-dimensional electron waveguides, which form a quantum resistor network, are presented here in four-terminal configurations. The transmission behaviors through such four-terminal networks are evaluated and classified. In addition, we show that such networks can be used as the basic building blocks for a possible massive wave computing machine in the future. In a network, each interconnection, a node point, is an elastic scatterer that routes the electron wave. Routing and rerouting of electron waves in a network is described in the framework of quantum transport from Landauer-Buttiker theory in the presence of multiple …

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Composite Structures Using Asphalt Based Roofing Scrap Materials: Eiera -- Final Report, V. J. Flanigan, K. Chandrashekhara, Susan L. Murray Sep 2002

Composite Structures Using Asphalt Based Roofing Scrap Materials: Eiera -- Final Report, V. J. Flanigan, K. Chandrashekhara, Susan L. Murray

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The uses of recycled materials in composites provide the potential for large cost savings and a solution to the ever-growing disposal problem. Shingles contain petroleum based binders and fillers, which used as a valuable resource in composite production. Composites offer inherent advantages over traditional materials in regard to corrosion resistance, design flexibility and extended service life. Use of scrap-roofing shingles as a core material in glass fiber reinforced composite materials offer potential low cost composite products such as sound barrier system, railroad ties and other building materials including blocks. In the present work, processes have been developed for shredding scrap …

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Laser Aided Part Repair -- A Review, Jinglei Wang, Sashikanth Prakash, Yashodhan Joshi, Frank W. Liou Aug 2002

Laser Aided Part Repair -- A Review, Jinglei Wang, Sashikanth Prakash, Yashodhan Joshi, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser aided part-repair is an emerging trend that has great potential for future industrial applications. Part-repair technologies are currently used in repairing military and civilian equipment. The focus of this paper is to review the current repair processes, which use the laser-aided metal deposition technology. Many metal parts, which are worn by continual use, can be restored to working condition by the deposition of metal with a laser and machining. This not only extends the life of the part, but also, saves on cost. A comparison between various processes, their parameters, efficiency, cost, and etc. are also presented. The process …

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Object-Oriented Modeling And Fauly Detection Of A Powder Feeder For A Laser Metal Deposition System, Robert G. Landers, Michael Gene Hilgers, Frank W. Liou, Bruce M. Mcmillin Aug 2002

Object-Oriented Modeling And Fauly Detection Of A Powder Feeder For A Laser Metal Deposition System, Robert G. Landers, Michael Gene Hilgers, Frank W. Liou, Bruce M. Mcmillin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

One of the most critical components of a laser metal deposition system is the powder feeder unit. Techniques are required to efficiently design and analyze these systems and to ensure fault tolerance during the operation. In this paper, a model of the powder feeder unit, based on object- oriented abstractions of it components, is developed. This model is modular in that specific components can be efficiently updated or replaced with components that perform a similar function. In addition, the model can be used for simulation allowing for efficient design and analysis. Assurance of the correctness of the powder feeder system …

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A Study On Effects Of Process Parameters In Rapid Freeze Prototyping, Frances D. Bryant, Guanghua Sui, Ming-Chuan Leu Aug 2002

A Study On Effects Of Process Parameters In Rapid Freeze Prototyping, Frances D. Bryant, Guanghua Sui, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Rapid Freeze Prototyping (RFP) is a relatively new solid freeform fabrication process, which builds a three-dimensional part according to a CAD model by depositing and freezing water droplets layer by layer. A study on the effects of RFP process parameters including the nozzle scanning speed, droplet size, and droplet frequency in building ice parts with a single-nozzle work head is made. Presented in this paper are the results of this study which indicate that these process parameters determine the ice layer thickness and ice line width, which in turn determine the surface roughness and the waiting time required after depositing …

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Object-Oriented Modeling And Fault Detection Of A Powder Feeder For A Laser Metal Deposition System, Robert G. Landers, Michael Gene Hilgers, Frank W. Liou, Bruce M. Mcmillin Aug 2002

Object-Oriented Modeling And Fault Detection Of A Powder Feeder For A Laser Metal Deposition System, Robert G. Landers, Michael Gene Hilgers, Frank W. Liou, Bruce M. Mcmillin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

One of the most critical components of a laser metal deposition system is the powder feeder unit. Techniques are required to efficiently design and analyze these systems and to ensure fault tolerance during the operation. In this paper, a model of the powder feeder unit, based on object-oriented abstractions of it components, is developed. This model is modular in that specific components can be efficiently updated or replaced with components that perform a similar function. In addition, the model can be used for simulation allowing for efficient design and analysis. Assurance of the correctness of the powder feeder system is …

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System Integration And Real-Time Control Architecture Of A Laser Aided Manufacturing Process, Mallikharjuna R. Boddu, Robert G. Landers, Srinivas Musti, Sanjeev Agarwal, Jianzhong Ruan, Frank W. Liou Aug 2002

System Integration And Real-Time Control Architecture Of A Laser Aided Manufacturing Process, Mallikharjuna R. Boddu, Robert G. Landers, Srinivas Musti, Sanjeev Agarwal, Jianzhong Ruan, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper discusses a hybrid deposition–removal manufacturing system being developed at the University of Missouri--Rolla. The system consists of a laser system, five-axis CNC machining center, and powder feeder system. A description of the control software, real-time control architecture, and integration of various subsystems to build the hybrid system is given. The interaction of the real-time controller with various sensors and subsystems to monitor and regulate the process is presented. The communication between integrated process planning for the system and real–time control is also discussed in this paper.

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Investigation Of Part Accuracy And Surface Roughness In Rapid Freeze Prototyping Based Investment Casting, Qingbin Liu, Ming-Chuan Leu, Stephen M. Schmitt Aug 2002

Investigation Of Part Accuracy And Surface Roughness In Rapid Freeze Prototyping Based Investment Casting, Qingbin Liu, Ming-Chuan Leu, Stephen M. Schmitt

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The study as described in this paper is aimed at investigating the dimensional accuracy and surface finish of metal parts made by investment casting with ice patterns generated by rapid freeze prototyping. The process of investment casting with ice patterns is described and contrast with conventional investment casting with wax patterns is made. The selection of binder material for ceramic slurries and the need for an interface agent to separate the ice pattern from the ceramic slurry in the mold making process are discussed. The accuracy and surface finish of ice patterns and of the metal castings are presented and …

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New Plane Wave Representation Of Point Sources, L. (Lijun) J. Jiang, W. C. Chew Aug 2002

New Plane Wave Representation Of Point Sources, L. (Lijun) J. Jiang, W. C. Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A new method to decompose the spherical wave of a 3D point source into plane waves is discussed. Using Cauchy's theorem, it represents spherical waves as the summation of surface-direction-wave integrals. Results show that only 6 directions waves needed storage. Thus, the method provides a good cost reduction for plane-wave related algorithms.

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Ccfss Technical Bulletin August 2002, Wei-Wen Yu Center For Cold-Formed Steel Structures Aug 2002

Ccfss Technical Bulletin August 2002, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.

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Fdtd Analysis Of Printed Circuit Boards Containing Wideband Lorentzian Dielectric Dispersive Media, Marina Koledintseva, David Pommerenke, James L. Drewniak Aug 2002

Fdtd Analysis Of Printed Circuit Boards Containing Wideband Lorentzian Dielectric Dispersive Media, Marina Koledintseva, David Pommerenke, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A Lorentzian model as the general case of a frequency-dependent behavior of a dispersive dielectric material is considered in this paper. Recursive convolution algorithms for the finite-difference time-domain (FDTD) technique for two cases of a Lorentzian medium, narrowband and wideband, depending on the ratio of a resonance line half-width at -3 dB and the resonance frequency of the material, are detailed. It is shown that a wideband Lorentzian model of a dielectric FR-4 used in printed circuit boards is more flexible and gives good agreement with experimental curves, and may be preferable as compared to a Debye model.

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Surface Switching Characteristics Of Variable Permittivity Dielectrics, Wayne Huebner, Eric J. Carleton Aug 2002

Surface Switching Characteristics Of Variable Permittivity Dielectrics, Wayne Huebner, Eric J. Carleton

Materials Science and Engineering Faculty Research & Creative Works

Flashover voltage, lifetimes, and switch performance of insulators utilizing square thin and thick film electrodes were examined to determine the viability of using thin electrodes for reliable surface discharge switching. Gold, silver, and platinum were sputtered (0.25 µm) and screen printed (15 µm) onto Al2O3, TiO2, and modified BaTiO3 (MBT), then tested in air at 105 Pa, under vacuum (10-3/ torr), and while immersed in an insulating fluid, SF-2 (manufactured by 3M). For the measured range of 0.5 to 3 mm in air, the flashover voltage for all three insulators …

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Ccfss News August 2002, Wei-Wen Yu Center For Cold-Formed Steel Structures Aug 2002

Ccfss News August 2002, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.

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The Woman's Guide To Navigating The Ph.D. In Engineering & Science [Book Review], Mariesa Crow Aug 2002

The Woman's Guide To Navigating The Ph.D. In Engineering & Science [Book Review], Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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Estimating Dc Power Bus Noise, Jingkun Mao, Bruce Archambeault, James L. Drewniak, Thomas Van Doren Aug 2002

Estimating Dc Power Bus Noise, Jingkun Mao, Bruce Archambeault, James L. Drewniak, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Simultaneous switching noise (SSN) resulting from IC devices can result in significant power bus noise, as well as radiation problems. An approach for estimating the power bus noise spectrum is presented in this paper. The power bus noise caused by digital circuits injecting high-frequency noise onto the DC buses feeding digital devices is calculated. The transient current drawn by an IC device is modeled using the load current and the shoot-through current through the power dissipation capacitance. Modeling and experimental results for several digital chips are shown. The modeling agrees well with the experimental results.

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Modeling Noise Coupling From Non-Parallel Pcb Trace Routing, Shaofeng Luan, Fengchao Xiao, W. Liu, Jun Fan, Yoshio Kami, James L. Drewniak, Richard E. Dubroff Aug 2002

Modeling Noise Coupling From Non-Parallel Pcb Trace Routing, Shaofeng Luan, Fengchao Xiao, W. Liu, Jun Fan, Yoshio Kami, James L. Drewniak, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

Coupling between PCB signal traces in proximity is of concern to PCB designers and EMC engineers. The behavior of noise coupling between non-parallel microstrip lines is studied in this paper by a full-wave numerical modeling method CEMPIE, designating a circuit extraction approach based on a mixed-potential integral equation formulation. Good agreement between the numerical results and measurements was obtained.

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Transmission Line Modeling Of Vias In Differential Signals, Chen Wang, James L. Drewniak, Jun Fan, James L. Knighten, Norman W. Smith, Ray Alexander Aug 2002

Transmission Line Modeling Of Vias In Differential Signals, Chen Wang, James L. Drewniak, Jun Fan, James L. Knighten, Norman W. Smith, Ray Alexander

Electrical and Computer Engineering Faculty Research & Creative Works

Signal layer transitions in differential lines are modeled using both FDTD and equivalent circuit methods. The equivalent circuit is developed based on transmission-line reasoning regarding via behavior. Parameters of each transmission-line segment are obtained based on its corresponding physical geometry. The mixed-mode S-parameters from the equivalent circuit and the FDTD modeling are compared. Good agreement is demonstrated in the frequency range from 1 GHz to 20 GHz. The results indicate that vias in differential lines can be modeled as a transmission line for a quick and easy engineering estimation of the differential signal behavior in an environment of signal layer …

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External Parasitic Inductance In Microstrip And Stripline Geometries Of Finite Size, Marina Koledintseva, James L. Drewniak, Thomas Van Doren, David M. Hockanson Aug 2002

External Parasitic Inductance In Microstrip And Stripline Geometries Of Finite Size, Marina Koledintseva, James L. Drewniak, Thomas Van Doren, David M. Hockanson

Electrical and Computer Engineering Faculty Research & Creative Works

An external parasitic ground (return) plane inductance, or a mutual inductance associated with fringing magnetic fields in planar transmission line structures, is the culprit of common-mode voltage (ground plane noise) that leads to parasitic radiation of the corresponding unintentional "antennas" in high-speed electronic equipment. Mutual inductance of this sort in microstrip and stripline structures is studied here using an analytical quasi- magnetostatic approach and FDTD modeling. Closed-form expressions for mutual inductance in symmetrical and asymmetrical microstrip and stripline structures are presented.

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