Engineering Commons^™

Dc Power Bus Modeling Using A Circuit Extraction Approach Based On A Mixed-Potential Integral Equation Formulation And An Iterative Equation Solver, Jun Fan, James L. Drewniak, James L. Knighten

Electrical and Computer Engineering Faculty Research & Creative Works

A quick and simple approach is developed to perform circuit simulations for an equivalent circuit extracted from a first principles formulation for DC power bus structures. The simulations are done by solving the system equation using an iterative method. Good agreement between modeling and measurements demonstrate the effectiveness of the method, which is very suitable and computationally efficient for frequency-domain DC power modeling.

Evaluation Of Nickel Deposition By Electrochemical Impedance Spectroscopy, M. Holm, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

Electrochemical impedance spectroscopy was used to characterize the deposition of nickel from unbuffered acid sulfate electrolytes, from which a wide range of deposit morphologies and current efficiencies are possible. The operating parameters were in the range of 40 to 60 g L-1 Ni2+, 40 to 60 °C, and the pH from 2.0 to 3.5. The resulting impedance spectra for nickel deposition at 20 mA cm-2 consisted of one or two characteristic loops whose frequency and capacitance were dependent upon the electrowinning conditions and indicative of the resultant deposit morphology. A single high frequency capacitive loop, on the order of 1 …

Statcom Control For Power System Voltage Control Applications, Pranesh Rao, Zhiping Yang, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

A static compensator (STATCOM) is a device that can provide reactive support to a bus. It consists of voltage sourced converters connected to an energy storage device on one side and to the power system on the other. In this paper the conventional method of PI control is compared and contrasted with various feedback control strategies. A linear optimal control based on LQR control is shown to be superior in terms of response profile and control effort required. These methodologies are applied to an example power system

Laboratories Teaching Concepts In Microcontrollers And Hardware-Software Co-Design, Daryl G. Beetner, Hardy J. Pottinger, Kyle Mitchell

Electrical and Computer Engineering Faculty Research & Creative Works

Hardware software co-design is becoming increasingly important to the embedded systems industry. It will soon be fundamental to digital systems design. As such, students in electrical and computer engineering and in computer science should be introduced to hardware-software co-design early in their undergraduate education.

We are designing laboratory modules which introduce concepts of hardware-software co-design in an undergraduate's first course on microcontrollers and digital systems design. Students use design automation tools to develop FPGA-based hardware for use with an 8051-microcontroller and use common software development tools to develop microcontroller software in C or assembly language. Co-simulation of hardware and software …

Dc Power Bus Design With Fdtd Modeling Including A Dispersive Media, Xiaoning Ye, Jun Fan, Marina Koledintseva, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

DC power-bus modeling in high-speed digital design using the FDTD method is reported here. The dispersive medium is approximated by a Debye model to account for the loss. A wide band frequency response (100 MHz-5 GHz) is obtained through a single FDTD simulation. Favorable agreement is achieved between the modeled and measured results for a typical DC power-bus structure with multiple SMT decoupling capacitors mounted on the board. The FDTD tool is then applied to investigate the effects of local decoupling on a DC power-bus. The modeled results agree with the results from another modeling tool, the CEMPIE (a circuit …

Film Mass Transfer Coefficient Expressions For Electroosmotic Flows, Athanasios I. Liapis, Brian A. Grimes

Chemical and Biochemical Engineering Faculty Research & Creative Works

Expressions are developed and presented that could be used to determine the film mass transfer coefficient of a solute in electroosmotic flows. In contrast to pressure-driven flows at low Reynolds numbers where the film mass transfer coefficient is independent of the linear characteristic dimension of the channel for flow, in electroosmotically driven flows at low Reynolds numbers the film mass transfer coefficient is shown to be a function of the ratio R/λ, where R is the channel radius and λ is the Debye length. This result implies that for electroosmotically driven flows in a packed bed or porous monolith with …

Performance Monitoring In Umr's Solar Car, Louis Mccarthy, Josh Pieper, Aaron Rues, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

We describe the instrumentation in UMR's solar car. Accurate knowledge of the operating parameters inside the solar car is shown to be crucial to maintaining high efficiency and reliability. The power trackers keep the solar array operating at its highest efficiency by conditioning the input and maintaining the maximum power point of the solar cells.

Simulation Of Temperature And Stress Fields During Rcc Dam Construction, Ronaldo Luna, Yongfu Wu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The worldwide experience in the construction of roller-compacted concrete (RCC) dams together with the use of numerical solutions, allows the simulation of different scenarios in a computer. It is well documented that thermal control is one of the most important problems for RCC dam construction. The dam temperature changes due to the heat produced by the internal hydration of concrete and the environmental boundary conditions influencing the elastic modulus and creep properties of concrete. The construction process was simulated to study how the temperature and stress change during dam construction. The numerical methodology considers the effect of temperature on the …

Determination Of The Intraparticle Electroosmotic Volumetric Flow-Rate, Velocity And Peclet Number In Capillary Electrochromatography From Pore Network Theory, B. A. Grimes, J. J. Meyers, Athanasios I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

The results obtained from the pore network model employed in this work, clearly show that the magnitudes of the intraparticle electroosmotic volumetric flowrate, Q(intrap), and velocity, < v (intrap,x) >, in the pores of the charged porous silica particles considered in this study are greater than zero. The intraparticle Peclet number, Pe(intra), of a solute in these charged porous silica particles would be greater than zero, and, in fact, the magnitude of the intraparticle Peclet number, Pe(intrap), of lysozyme is greater than unity for all the values of the pore connectivity, n(T), of the intraparticle pores and of the applied electric potential difference …

Study On Water Deposit In Rapid Freeze Prototyping Process, Guanghua Sui, Weihan Zhang, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Rapid Freeze Prototyping (RFP) builds a three-dimensional ice part according to its CAD model by depositing and rapidly freezing water in a layer-by-layer manner. To study the water deposit in RFP, assumptions are made based on the deformation of water droplet impinging on a flat substrate, the thermal analysis of a new layer of water deposit, and the characteristics of solidification of a water drop. The equations governing the cross-sectional profile of the water deposit are then established. A model of water deposit is proposed by simplifying the equations under our experimental conditions in RFP. By using this model, equations …

Laser Additive Manufacturing Process Planning And Automation, Jun Zhang, Jianzhong Ruan, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a Laser Additive Manufacturing Process Planning (LAMPP) being developed at the University of Missouri-Rolla. The off-line planning recognizes difficult-to-build features from an STL file, selects optimal part orientation and building directions based on the skeleton information of the object geometry, and optimizes the sub-process sequences for deposition and machining. During the optimization of the subpart building processes, collaboration between the deposition process planner and the machining process planner is needed to check the deposition availability and machinability. As a result, tool paths for both the laser head and the machining head are automatically generated.

Determination And Improvement Of Building Speed In Rapid Freeze Prototyping, Wei Zhang, Guanghua Sui, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Rapid freeze prototyping (RFP) is a solid freeform fabrication process that builds an ice part by rapidly freezing water in a layer by layer manner. One advantage of this process is the ability to build ice parts faster than other SFF processes. The factors that affect the speed of contour building and interior filling in RFP are identified. The influence of these factors is analyzed through heat transfer and material flow analyses. A model based on heat transfer analysis is proposed to determine the maximum achievable speed of contour building under stable conditions. Experiments are conducted to validate the performance …

Investment Casting With Ice Patterns Made By Rapid Freeze Prototyping, Wei Zhang, Ming-Chuan Leu, Chao Feng, Rong Ren, Renjie Zhang, Qingping Lu, Jubu Jiang, Yongnian Yan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

One of the most promising applications of rapid freeze prototyping (RFP) is making metal parts by investment casting with the built ice parts. The integration of RFP and investment casting allows fast creation of complex net-shape metal parts directly from their CAD models. The advantages of doing so include no part geometric complexity limitation, no experience of parting line design and assembling needed, clean and low-cost of process operation, and good performance. In this paper, we will present our recent study on binder selection, slurry making, ceramic shell making, and the casting results of the metal parts.

Process Modeling, Monitoring And Control Of Laser Metal Forming, N. Munjuluri, Sanjeev Agarwal, Frank W. Liou

Electrical and Computer Engineering Faculty Research & Creative Works

Laser Metal Forming (LMF) process is one of the prominent Rapid Prototyping (RP) process that can be used to develop functional and fully dense metal parts. This paper addresses process modeling, monitoring and control of a laser metal forming system currently under development at Laser Aided Manufacturing Processes (LAMP) laboratory at University of Missouri--Rolla. This LMF system is based on a 2.5kW Nd:YAG laser as energy source and integrates five axis metal deposition and five axis machining. The current paper is aimed at characterization of effects of operating parameters such as traverse speed, mass flow-rate and laser power on the …

Distoritonal Buckling Of Cold-Formed Steel Columns, Benjamin W. Schafer

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

No abstract provided.

Ccfss Technical Bulletin August 2000, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.

Ccfss News August 2000, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.

Emi From Airflow Aperture Arrays In Shielding Enclosures-Experiments, Fdtd, And Mom Modeling, Min Li, Joe Nuebel, James L. Drewniak, Richard E. Dubroff, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Aperture arrays designed to provide airflow through shielding enclosures can provide part of the coupling path from interior sources to external electromagnetic interference (EMI). In this work, radiation through aperture arrays is investigated numerically and experimentally. FDTD modeling is compared with measurements on aperture arrays in a test enclosure. The method of moments (MoM) is also utilized to study radiation from apertures and to investigate the mutual coupling between apertures in an infinite conducting plane. A simple design equation for the relation between aperture size and number and shielding effectiveness is proposed.

Experimental And Numerical Study Of The Radiation From Microstrip Bends, H. Wang, Yun Ji, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

This paper investigates the radiation from microstrip lines with 90-degree bends. A 1-GHz TEM cell is used to measure the radiation from microstrip lines with different kinds of bends. A full wave hybrid FEM/MoM code is used to compute the radiation. Both experimental and numerical results show that there is no significant difference between the radiation from right angle bends and bends with two 45-degree corners at frequencies and trace dimensions that are likely to be found on printed circuit boards.

Fdtd And Fem/Mom Modeling Of Emi Resulting From A Trace Near A Pcb Edge, Daniel P. Berg, Motoshi Tanaka, Yun Ji, Xiaoning Ye, James L. Drewniak, Todd H. Hubing, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

PCB traces routed near board edges and carrying high-speed signals are considered to contribute to EMI problems. Consequently, design maxims state that traces that might have intentional or unintentional high frequency components on them be kept away from board edges. This costs valuable surface area as boards become more densely designed. Further, design maxims concerning traces near board edges are not well quantified. The increase in EMI as a trace is routed increasingly closer to the PCB edge has been studied experimentally and with numerical modeling.

Experimental And Fdtd Study Of The Emi Performance Of An Open-Pin-Field Connector For Modules-On-Backplanes, Xiaoning Ye, Jim Nadolny, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Experimental measurements and numerical modeling were used to study the EMI performance of a module-on-backplane connector for various configurations of signal-return pin-outs. A commercially available open-pin-field connector was used in these results to connect between the mother-board and the daughter-card. The experimental techniques, based on measuring |S₂₁|, included both common-mode current measurements and monopole near-field probe measurements. The FDTD method was used to provide numerical support of the near-field measurements and generally agreed with the measured results for frequencies up to 3 GHz. The FDTD method was also used to investigate the relationship between the radiated EMI at …

Distributed Arithmetic Implementation Of Multivariable Controllers For Smart Structural Systems, Lingfeng Yuan, Sridhar Sana, Hardy J. Pottinger, Vittal S. Rao

Electrical and Computer Engineering Faculty Research & Creative Works

Smart structural systems require the electronic control systems which are integrated into the structures to be small, lightweight and power-efficient. The field programmable gate array (FPGA) is a good platform to implement such controllers. In our previous work, FPGA-based digital controllers were built and tested on a simple structural system. In order to implement multivariable controllers, the hardware resources for FPGA-based architecture need to be further reduced. Distributed arithmetic (DA) has long been proven to be a very efficient means to mechanize computations that are dominated by inner products involving constant multiplicand. The computational requirements of the smart structural controllers …

Emc Analysis Of An 18" Lcd Monitor, Theodore M. Zeeff, Todd H. Hubing, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes a case study covering the evaluation and reduction of the radiated EMI from an 18 inches Liquid Crystal Display (LCD) monitor. The evaluation was completed in two parts: first potential EMI sources at the Printed Circuit Board (PCB) level were identified, then the EMI antennas driven by these sources were analyzed. Methods for reducing the EMI were described in detail, and where applicable, those modifications were applied. Radiated measurements demonstrate the effectiveness of these recommendations.

Experimental Evaluation Of Power Bus Decoupling On A 4-Layer Printed Circuit Board, Juan Chen, Minjia Xu, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The switching of active devices on printed circuit boards (PCBs) can cause a momentary surge or drop in the power bus voltage. Decoupling capacitors are often utilized to alleviate this problem. They help to stabilize the power bus voltage by supplying transient current to active devices. The decoupling strategy, including where to place the high-frequency decoupling capacitors, is often a topic of debate. This paper examines the effect of decoupling capacitor placement on a 4-layer printed circuit board. Some design guidelines are provided.

Finite Element Modeling Of Patch Antenna And Cavity Sources, Yun Ji, Todd H. Hubing, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

This paper examines two different approaches that can be used to model patch antennas and cavities fed by a coaxial cable. The probe model represents the feed as a current filament along the center conductor of the coaxial cable. The coaxial-cable model enforces the analytical field distribution at the cable opening. These two models have been implemented in a hybrid FEM/MoM code. A power bus structure and a cavity geometry with coaxial-cable feeds are investigated. Numerical results obtained for these two examples are compared with measurements. It is shown that the probe model should only be applied to electrically short …

High Efficiency Separation Of Microbial Aggregates Using Capillary Electrophoresis, J. M. Schneiderheinze, Daniel W. Armstrong, G. Schulte, David J. Westenberg

Chemistry Faculty Research & Creative Works

Recent advances in the technique of capillary electrophoresis have demonstrated fast, highly efficient separation of mixtures of intact microbes. This paper describes the application of this technique for the separation of microbial aggregates of Micrococcus luteus, Saccharomyces cerevisiae, or Alcaligenes faecalis. The aggregates of these microbes were resolved into several highly efficient peaks with analysis times under 10 min and efficiencies approaching 1 000 000 plates m-1 in some cases. A reproducible relationship was found between the electrophoretic mobility and the aggregation number or size of the cluster under a given set of experimental conditions. Often, cellular aggregation was reversible …

Development Of A Closed-Form Expression For The Input Impedance Of Power-Ground Plane Structures, Minjia Xu, Yun Ji, Todd H. Hubing, Thomas Van Doren, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

This paper analyzes the fundamental behavior of PCB power bus structures using the modal expansion method. The results are validated by experiments and full-wave numerical modeling. It is shown that the power bus can be modeled as a series L_eC circuit below the first board resonance frequency. C is the interplane capacitance and L_e is an effective inductance contributed by all the cavity nodes. The effects of the layer thickness, port location, board size and the feeding wire radius on the value of L_e are discussed in this study. L_e can be estimated from the …

The Emi Benefits Of Ground Plane Stitching In Multi-Layer Power Bus Stacks, Xiaoning Ye, David M. Hockanson, Min Li, Wei Cui, S. Radu, James L. Drewniak, Thomas Van Doren, Todd H. Hubing, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The effect on EMI of stitching multiple ground planes together along the periphery of multi-layer PCB stacks is studied. Power bus noise induced EMI and radiation from the board edges is the major concern herein. The EMI at 3 meters for different via stitch spacing and layer thickness is modeled with FDTD modeling. It is shown that the ground plane stitching effectively reduces the radiated EMI that results from fringing fields at the power bus edges. Two families of curves are generated to demonstrate the variation of the radiated EMI as a function of layer thickness and stitch spacing. Further …

Quantifying Decoupling Capacitor Location, Jun Fan, James L. Knighten, Antonio Orlandi, Norman W. Smith, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Decoupling capacitor location in DC power bus design is a critical design choice for which proven guidelines are not well established. The mutual inductance between two closely spaced vias can have a great impact on the coupling between an IC and a decoupling capacitor. This coupling is a function of the spacing between the IC and capacitor, and spacing between power and ground layers. The impact of the mutual inductance on decoupling, i.e., local versus global decoupling, was studied, using a circuit extraction approach based on a mixed-potential integral equation. Modeling indicates that local decoupling has benefits over global decoupling …

Information Models For Planning And Scheduling Of Chemical Processes, Neil L. Book, Vivek Bhatnagar

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Process Data Exchange Institute (pdXi) has developed an information model for process engineering data. The pdxi information model is designed to facilitate the storage and exchange of steady-state process engineering data. Batch and real-time operating data can be stored and exchanged using the pdXi model as snapshots (data that characterizes the process at a specific point in time). Snapshots are an inefficient method for storing and exchanging batch and real-time data. Also, snapshots do not contain data that describe the processes that occur between snapshots. Sharma and Book modified the basic structure of the pdXi information model to make …