Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Faculty Publications

Discipline
Institution
Keyword
Publication Year
File Type

Articles 2581 - 2610 of 3294

Full-Text Articles in Engineering

Linear Voltage To Current Conversion Using Submicron Cmos Devices, David J. Comer, Donald Comer, Aaron Shreeve May 2004

Linear Voltage To Current Conversion Using Submicron Cmos Devices, David J. Comer, Donald Comer, Aaron Shreeve

Faculty Publications

Sponsorship: AMIS--American Micro-Systems, Inc. This paper investigates the linearity of submicron gate length CMOS devices and their behavior in open loop voltage to current (V-I) converters. Methods are developed to estimate the deviation from linearity in V-I converters due to short-channel effects. Using these methods, a converter is designed and fabricated on a 0.35 micron process. The measured deviation from linearity is less than 1% and the simulated bandwidth is 1 GHz.

Go to article

Control Strategies For Active Power Sharing In A Fuel-Cell-Powered Battery-Charging Station, Zhenhua Jiang, Roger A. Dougal May 2004

Control Strategies For Active Power Sharing In A Fuel-Cell-Powered Battery-Charging Station, Zhenhua Jiang, Roger A. Dougal

Faculty Publications

This paper presents an effective system design for a fuel-cell-powered battery-charging station and three control strategies for active power sharing among the batteries. This battery-charging station allows multiple batteries to be simultaneously charged. Three control strategies were investigated to coordinate the active power distribution among the battery-charging branches. The baseline control strategy Was equal rate charging. Two advanced control strategies, proportional rate charging and pulse current charging, were compared to the baseline strategy. These control strategies were realized in MaTLaB/Simulink, and the current and voltage regulations were implemented using the classical proportional-integral control approach. The system simulation was conducted in …

Go to article

On Noncoherent Detection Of Cpm, Michael D. Rice, Erik Perrins Apr 2004

On Noncoherent Detection Of Cpm, Michael D. Rice, Erik Perrins

Faculty Publications

This work was supported under a grant from the Air Force ARTM program (Contracts F04700-02-P-0080 and F04700-02-P-0081). It is well understood that the performance of noncoherent receivers with multi-symbol observation intervals approaches that of coherent receivers as the observation interval grows arbitrarily large. However, since complexity also grows exponentially with observation length, there are practical limits to this approach. In this paper we present a noncoherent receiver for continuous phase modulation (CPM) whose structure is a hybrid between existing coherent and noncoherent receiver architectures. The presentation is given in the most general M-ary multi-h terms, with some emphasis on the …

Go to article

Noble Metal Nanostructures Synthesized Inside Mesoporous Nanotemplate Pores, J. Arbiol, E. Rossinyol, A. Cabot, F. Peiro, A. Cornet, J. R. Morante, Fanglin Chen, Meilin Liu Apr 2004

Noble Metal Nanostructures Synthesized Inside Mesoporous Nanotemplate Pores, J. Arbiol, E. Rossinyol, A. Cabot, F. Peiro, A. Cornet, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Noble metal impregnation has resulted in the inclusion of metal nanostructures within the SBA-15 mesoporous silica hexagonal pores (from nanoclusters to nanowires). A bright-field transmission electron microscopy three-dimensional reconstruction is proposed to analyze the localization of nanostructures within the pores of mesoporous nanotemplates. The method allows corroboration whether the nanostructures are synthesized inside the pores or they are synthesized alternatively on the nanotemplate aggregates exterior surface.

Go to article

Molecular-Dynamics Simulation Of The Effect Of Ions On A Liquid–Liquid Interface For A Partially Miscible Mixture, Richard L. Rowley, Kent E. Wardle, Eric Carlson, Douglas Henderson Apr 2004

Molecular-Dynamics Simulation Of The Effect Of Ions On A Liquid–Liquid Interface For A Partially Miscible Mixture, Richard L. Rowley, Kent E. Wardle, Eric Carlson, Douglas Henderson

Faculty Publications

Molecular-dynamics simulations were performed to model the effect of added salt ions on the liquid-liquid interface in a partially miscible system. Simulations of the interface between saturated phases of a model 1-hexanol + water system show a bilayer structure of 1-hexanol molecules at the interface with OH heads of the first layer directed into the water phase and the opposite orientation for the second layer. The alignment of the polar OH groups at the interface stabilizes a charge separation of sodium and chloride ions when salt is introduced into the aqueous phase, producing an electrical double layer. Chloride ions aggregate …

Go to article

Gradient-Based Non-Linear Microstructure Design, Brent L. Adams, M. Lyon Apr 2004

Gradient-Based Non-Linear Microstructure Design, Brent L. Adams, M. Lyon

Faculty Publications

The support of this research by the Army Research Office is gratefully acknowledged. M. Lyon is supported by a National Science Foundation Graduate Research Fellowship. Fourier analysis is implemented on the orientation distribution of a polycrystalline microstructure. The linearity and convexity of the Fourier space, with respect to orientation, allows one to consider all possible distributions by considering all linear combinations of single-grain orientations. The limits of the Fourier space are therefore defined by the solutions to a set of linear programming problems. A unique approach to the linear programming, similar to the Krylov subspace methods for obtaining solutions to …

Go to article

Gas-Diffusion Process In A Tubular Cathode Substrate Of A Sofc, Part Ii: Identification Of Gas-Diffusion Process Using Ac Impedance Method, Kevin Huang Apr 2004

Gas-Diffusion Process In A Tubular Cathode Substrate Of A Sofc, Part Ii: Identification Of Gas-Diffusion Process Using Ac Impedance Method, Kevin Huang

Faculty Publications

The effects of cathodic dc bias, bulk pO2, and effective O2 -diffusivity on ac impedance spectra of Siemens Westinghouse Power Corporation’s cathode-supported solid oxide fuel cells were systematically studied over a temperature range of 800 to 1000°C. It was found that the activation process dominated the overall electrode kinetics at 800°C, by which the applied dc bias reduced the electrode resistance considerably. With increasing the temperature to above 900°C, the activation process became effectively activated, leading to a visible arc at the lowest frequency on the impedance spectrum, which is relevant to the pore gas-diffusion process. …

Go to article

Gas-Diffusion Process In A Tubular Cathode Substrate Of An Sofc, Part I: Theoretical Analysis Of Gas-Diffusion Process Under Cylindrical Coordinate System, Kevin Huang Apr 2004

Gas-Diffusion Process In A Tubular Cathode Substrate Of An Sofc, Part I: Theoretical Analysis Of Gas-Diffusion Process Under Cylindrical Coordinate System, Kevin Huang

Faculty Publications

In this the first part of a two-part paper, the gas-diffusion process through a thick and porous tubular cathode substrate of a solid oxide fuel cell-(SOFC) was theoretically analyzed using classic Fick’s diffusion equation under the cylindrical coordinate system. The effects of current density, temperature, oxygen diffusivity or porosity, wall thickness, and bulk pO2 on the concentration (or pore in this paper) polarization were calculated and are presented graphically. The results clearly show a greater impact on pore polarization by current density, oxygen diffusivity, wall thickness, and bulk pO2, but not by temperature. In addition, …

Go to article

Metrics For Human Driving Of Multiple Robots, Dan R. Olsen Jr., Jonathan Turner, Stephen Bart Wood Apr 2004

Metrics For Human Driving Of Multiple Robots, Dan R. Olsen Jr., Jonathan Turner, Stephen Bart Wood

Faculty Publications

A goal of human-robot interaction is to expand the capability of human beings so that they can control multiple robots simultaneously. This provides leverage for human attention beyond single robot interaction. The number of such robots that can be operated is called the fan-out of a human-robot team. We define the concepts of neglect-tolerance as a measure of autonomy and interaction-effort as a measure of required human attention. A model for fan-out is presented that predicts a human's ability to control multiple robots. We validate this model using robot simulations and user studies. Using the validated model we demonstrate enhanced …

Go to article

Synthesis Of Tin Oxide Nanostructures With Controlled Particle Size Using Mesoporous Frameworks, A. Cabot, J. Arbiol, E. Rossinyol, J. R. Morante, Fanglin Chen, Meilin Liu Mar 2004

Synthesis Of Tin Oxide Nanostructures With Controlled Particle Size Using Mesoporous Frameworks, A. Cabot, J. Arbiol, E. Rossinyol, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin oxide nanostructures with controlled narrow particle size distribution were synthesized inside silica mesoporous templates. In this way, particle growth was blocked by physically corseting the tin compound inside the silica frameworks, the pore diameter of which determines the final tin oxide crystallite size distribution. Template structures were subsequently eliminated by chemical methods to collect the unsupported semiconductor nanoparticles. Thus obtained tin oxed nanopowders, with particle sizes in the range between 6 and 10 nm, were structurally, chemically, and electically characterized. The results are compared with those obtained from the characterization of larger crystallite materials.

Go to article

Method Of Non-Data-Aided Carrier Recovery With Modulation Identification, Kenta Umebayashi, Robert H. Morelos-Zaragoza, Ryuji Kohno Mar 2004

Method Of Non-Data-Aided Carrier Recovery With Modulation Identification, Kenta Umebayashi, Robert H. Morelos-Zaragoza, Ryuji Kohno

Faculty Publications

A non-data aided carrier recovery technique using digital modulation format identification called multi-mode PLL (Phase Locked Loop) is proposed. This technique can be interpreted as a modulation identification method that is robust against static phase and frequency offsets. The performance of the proposed technique is studied and the analytical expressions are derived for the probability of lock detection, acquisition time over AWGN channel in the cases of M-PSK and M-QAM modulations with respect to frequency offset and signal-to-noise ratio.

Go to article

Symbolically Aided Model Development For An Induction Machine In Virtual Test Bed, Wenzhong Gao, Eugene V. Slovodnik, Roger A. Dougal Mar 2004

Symbolically Aided Model Development For An Induction Machine In Virtual Test Bed, Wenzhong Gao, Eugene V. Slovodnik, Roger A. Dougal

Faculty Publications

A new phase-domain induction machine model for use in power system dynamic simulation is developed with the aid of a symbolic tool. The symbolic tool can automatically construct a time-domain power system component model in the resistive companion form (RCF) that is widely used in time-domain simulators. The automatic differentiation technique (aDT) is utilized within the context of a symbolic modeling language, and the tool has been implemented for the virtual test bed (VTB) simulation environment. The new induction machine model was used to study start-up transients of an induction motor. The new model was verified by comparing the simulation …

Go to article

Development Of Commercially Viable Compliant Mechanisms Using The Pseudo-Rigid-Body Model: Case Studies Of Parallel Mechanisms, Christopher A. Mattson, Larry L. Howell, Spencer P. Magleby Mar 2004

Development Of Commercially Viable Compliant Mechanisms Using The Pseudo-Rigid-Body Model: Case Studies Of Parallel Mechanisms, Christopher A. Mattson, Larry L. Howell, Spencer P. Magleby

Faculty Publications

Analysis and synthesis of compliant mechanisms has recently been the subject of significant study in the research community. This focus has led to a number of design approaches for developing compliant mechanisms. This paper describes the value of using the Pseudo-Rigid-Body Model (PRBM) to design compliant mechanisms for commercial products. Application of the PRBM is illustrated through the development of two parallel mechanisms: a bicycle derailleur and parallel-motion bicycle brakes. The PRBM allows compliant mechanisms to be modeled and analyzed as rigid-body mechanisms and significantly reduces the complexity of analysis. Mechanisms with straightforward properties are used to demonstrate the use …

Go to article

Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson Mar 2004

Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson

Faculty Publications

This paper provides an analytical framework useful for assessing the use of all six electric and magnetic electromagnetic field polarizations for multiantenna communications systems. The approach uses a mapping between the induced signal currents and the received electromagnetic field in order to formulate a diversity interpretation of the six-polarization problem. Application of the framework to a simple, yet representative, channel model demonstrates that for full multipath elevation and azimuthal angle spread, six communication modes are theoretically possible. However, to implement the system requires more antenna design work since a straightforward implementation is found to reduce the potential number of modes …

Go to article

Surface States In Template Synthesized Tin Oxide Nanoparticles, A. Cabot, J. Arbiol, R. Ferre, J. R. Morante, Fanglin Chen, Meilin Liu Feb 2004

Surface States In Template Synthesized Tin Oxide Nanoparticles, A. Cabot, J. Arbiol, R. Ferre, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin–oxide nanoparticles with controlled narrow size distributions are synthesized while physically encapsulated inside silica mesoporous templates. By means of ultraviolet-visible spectroscopy, a redshift of the optical absorbance edge is observed. Photoluminescence measurements corroborate the existence of an optical transition at 3.2 eV. The associated band of states in the semiconductor gap is present even on template-synthesized nanopowders calcined at 800 °C, which contrasts with the evolution of the gap states measured on materials obtained by other methods. The gap states are thus considered to be surface localized, disappearing with surface faceting or being hidden by the surface-to-bulk ratio decrease.

Go to article

Comments On Hilbert Transform Based Signal Analysis, David G. Long Feb 2004

Comments On Hilbert Transform Based Signal Analysis, David G. Long

Faculty Publications

The use of the Hilbert transform for time/frequency analysis of signals is briefly considered. While the Hilbert transform is based on arbitrary continuous signals, most practical signals are digitially sampled and time-limited. To avoid aliasing in the sampling process the signals must also be bandlimited. It is argued that it is reasonable to consider such sampled signals as periodic (this is the basis of the Discrete Fourier Transform [DFT]) since any other interpretation is inconsistent. A simple derivation of the Hilbert transform for a sampled, periodic is then given. It is shown that the instantaneous frequency can be easily computed …

Go to article

Evaluating The Effect Of Rain On Seawinds Scatterometer Measurements, David G. Long, David Draper Feb 2004

Evaluating The Effect Of Rain On Seawinds Scatterometer Measurements, David G. Long, David Draper

Faculty Publications

A simple wind/rain backscatter model is used with co-located precipitation radar (PR) data from the Tropical Rainfall Measuring Mission (TRMM) satellite to evaluate the effect of rain on SeaWinds on QuikSCAT σ° observations. The model incorporates wind-induced surface scattering, the surface rain perturbation, and atmospheric rain attenuation and scattering. The co-located PR measurements afford direct computation of SeaWinds-scale averaged rain rate and atmospheric rain attenuation and scattering. An estimate of the wind-induced surface backscatter is computed via numerical weather prediction (NWP) winds. By synergistically combining the SeaWinds, NWP, and PR data, estimates of surface rain perturbation and combined surface/atmospheric scattering …

Go to article

Ultra-Wide (Uwb) Communications: New Paradigms And Opportunities., Robert H. Morelos-Zaragoza Feb 2004

Ultra-Wide (Uwb) Communications: New Paradigms And Opportunities., Robert H. Morelos-Zaragoza

Faculty Publications

In this talk, the unique characteristics of ultra wideband (UWB) communications systems are introduced. Receiver design considerations are presented. Focus is on the relation between the symbol duration and the delay spread of the channel. This determines whether the receiver should use a Rake receiver (Spread-spectrum system) or an equalizer (multiple carrier or OFDM system).

Go to article

Wide-Band/Dual-Band Packaged Antenna For 5-6 Ghz Wlan Application, Mohammod Ali, Tuangsit Sittironnarit, Huan-Sheng Hwang, Robert A. Sadler, Gerard James Hayes Feb 2004

Wide-Band/Dual-Band Packaged Antenna For 5-6 Ghz Wlan Application, Mohammod Ali, Tuangsit Sittironnarit, Huan-Sheng Hwang, Robert A. Sadler, Gerard James Hayes

Faculty Publications

A wide-band/dual-band packaged antenna is proposed for wireless local-area network (WLAN) applications in the 5.15-5.35 GHz and 5.725-5.825 GHz frequency range. The antenna is internal to the housing of a personal digital assistant, such as a Palm organizer, and has the dimensions of 28 by 9 by 3 ram on an FR4 substrate. The antenna meets or exceeds the bandwidth requirements for the dual-band IEEE 802.11a WLAN applications (5.15-5.35 GHz and 5.725-5.825 GHz) within 2:1 voltage standing-wave ratio.

Go to article

Laboratory Project In Wireless Fsk Receiver Design, Michael A. Jensen, Cynthia Fuse, Raymond Woodward Feb 2004

Laboratory Project In Wireless Fsk Receiver Design, Michael A. Jensen, Cynthia Fuse, Raymond Woodward

Faculty Publications

This paper describes a wireless local area network laboratory project that provides senior and first-year graduate students in microwave engineering courses the opportunity to design, build, and test several passive microstrip components and integrate them into a working system. Students design filters, couplers, amplifiers, diode detectors, quarter-wave transformers, antennas, and stub matching networks in weekly labs that parallel-lectures in a one-semester microwave engineering course. This paper also describes simple inexpensive prototyping and testing methods that have been used in this course. Laboratory materials and technical details of the design are provided on the web for students and educators.

Go to article

Transcriptome-Based Determination Of Multiple Transcription Regulator Activities In Escherichia Coli By Using Network Component Analysis, Katy Kao, Young-Lyeol Yang, Riccardo Boscolo, Chiara Sabatti, Vwani Roychowdhury, James Liao Jan 2004

Transcriptome-Based Determination Of Multiple Transcription Regulator Activities In Escherichia Coli By Using Network Component Analysis, Katy Kao, Young-Lyeol Yang, Riccardo Boscolo, Chiara Sabatti, Vwani Roychowdhury, James Liao

Faculty Publications

Cells adjust gene expression profiles in response to environmental and physiological changes through a series of signal transduction pathways. Upon activation or deactivation, the terminal regulators bind to or dissociate from DNA, respectively, and modulate transcriptional activities on particular promoters. Traditionally, individual reporter genes have been used to detect the activity of the transcription factors. This approach works well for simple, non-overlapping transcription pathways. For complex transcriptional networks, more sophisticated tools are required to deconvolute the contribution of each regulator. Here, we demonstrate the utility of network component analysis in determining multiple transcription factor activities based on transcriptome profiles and …

Go to article

Open-Ended Problem-Solving Skills In Thermal-Fluids Engineering, Nikos J. Mourtos, Nicole Dejong-Okamoto, Jinny Rhee Jan 2004

Open-Ended Problem-Solving Skills In Thermal-Fluids Engineering, Nikos J. Mourtos, Nicole Dejong-Okamoto, Jinny Rhee

Faculty Publications

Problem-solving skills have always been important in many professions. However, ABET EC 2000 recently placed a new focus on these skills in engineering education with outcome 3e, which states that engineering graduates must have an ability to identify, formulate and solve engineering problems. Problem-solving is defined as a process used to obtain a best answer to an unknown or a decision that is subject to some constraints. Problem-solving is not the same as textbook exercise solving, which is very common in engineering curricula. In the article, the authors first define engineering problem-solving and, in particular, what it means to identify …

Go to article

Effect Of Porosity On The Capacity Fade Of A Lithium-Ion Battery: Theory, Godfrey Sikha, Branko N. Popov, Ralph E. White Jan 2004

Effect Of Porosity On The Capacity Fade Of A Lithium-Ion Battery: Theory, Godfrey Sikha, Branko N. Popov, Ralph E. White

Faculty Publications

A mathematical model is presented to predict the performance of a lithium-ion battery. It includes the changes in the porosity of the material due to the reversible intercalation processes and the irreversible parasitic reaction. The model was also extended to predict the capacity fade in a lithium-ion battery based on the unwanted parasitic reaction that consumes Li+ along with the changes in the porosities of the electrodes with cycling due to the continuous parasitic side reaction. The model can be used to predict the drop in the voltage profile, change in the state of charge, and the effects of …

Go to article

Multiagent Systems With Workflows, José M. Vidal, Paul A. Buhler, Christian Stahl Jan 2004

Multiagent Systems With Workflows, José M. Vidal, Paul A. Buhler, Christian Stahl

Faculty Publications

Industry and researchers have two different visions for the future of Web services. Industry wants to capitalize on Web service technology to automate business processes via centralized workflow enactment. Researchers are interested in the dynamic composition of Web services. We show how these two visions are points in a continuum and discuss a possible path for bridging the gap between them.

Go to article

Design And Analysis Of An R-Shaped Dual-Band Planar Inverted-F Antenna For Vehicular Applications, Mohammod Ali, Guangli Yang, Huan-Sheng Hwang, Tuangsit Sittironnarit Jan 2004

Design And Analysis Of An R-Shaped Dual-Band Planar Inverted-F Antenna For Vehicular Applications, Mohammod Ali, Guangli Yang, Huan-Sheng Hwang, Tuangsit Sittironnarit

Faculty Publications

A dual-band R-shaped planar inverted-F antenna is proposed for vehicular application. Utilization of this unique geometry dual-frequency operation is achieved with a single feed. The proposed antenna operates in the 225- and 450-MHz bands. Input impedance and return loss data as function of various antenna parameters are presented, which show that parameters can be adjusted in order to obtain optimum tuning. Radiation pattern data for the antenna mounted on the roof of two types of vehicles are given. The pattern in the low-frequency band is essentially omnidirectional while that in the high-frequency band is directional and normal to the antenna …

Go to article

Exploration Of Artificial Multiferroic Thin-Film Heterostructures Using Composition Spreads, K.-S. Chang, M. A. Aronova, C.-L. Lin, M. Murakami, M.-H. Yu, Jason R. Hattrick-Simpers, O. O. Famodu, S. Y. Lee, R. Ramesh, M. Wuttig, I. Takeuchi, C. Gao, L. A. Bendersky Jan 2004

Exploration Of Artificial Multiferroic Thin-Film Heterostructures Using Composition Spreads, K.-S. Chang, M. A. Aronova, C.-L. Lin, M. Murakami, M.-H. Yu, Jason R. Hattrick-Simpers, O. O. Famodu, S. Y. Lee, R. Ramesh, M. Wuttig, I. Takeuchi, C. Gao, L. A. Bendersky

Faculty Publications

We have fabricated a series of composition spreads consisting of ferroelectric BaTiO3 and piezomagnetic CoFe2O4 layers of varying thicknesses modulated at nanometer level in order to explore artificial magnetoelectricthin-film heterostructures. Scanning microwavemicroscopy and scanning superconducting quantum interference device microscopy were used to map the dielectric and magnetic properties as a function of continuously changing average composition across the spreads, respectively. Compositions in the middle of the spreads were found to exhibit ferromagnetism while displaying a dielectric constant as high as ≈120.

Go to article

Series Solution To The Transient Convective Diffusion Equation For A Rotating Disk Electrode, Shiriram Santhanagopalan, Ralph E. White Jan 2004

Series Solution To The Transient Convective Diffusion Equation For A Rotating Disk Electrode, Shiriram Santhanagopalan, Ralph E. White

Faculty Publications

A series solution to the transient convective diffusion equation for the rotating disc electrode system is presented and compared to previously reported solutions. The solution presented here is for the entire time domain and agrees well with both the short and long time solutions presented earlier in the literature.

Go to article

Parameter Estimates For A Pemfc Cathode, Qingzhi Guo, Vijay A. Sethuraman, Ralph E. White Jan 2004

Parameter Estimates For A Pemfc Cathode, Qingzhi Guo, Vijay A. Sethuraman, Ralph E. White

Faculty Publications

Five parameters of a model of a polymer electrolyte membrane fuel cell (PEMFC) cathode (the volume fraction of gas pores in the gas diffusion layer, the volume fraction of gas pores in the catalyst layer, the exchange current density of the oxygen reduction reaction, the effective ionic conductivity of the electrolyte, and the ratio of the effective diffusion coefficient of oxygen in a flooded spherical agglomerate particle to the square of that particle radius) were determined by least-squares fitting of experimental polarization curves. The values of parameters obtained in this work indicate that ionic conduction and gas-phase transport are two …

Go to article

Analytical Solution For The Impedance Of A Porous Electrode, Sheba Devan, Venkat R. Subramanian, Ralph E. White Jan 2004

Analytical Solution For The Impedance Of A Porous Electrode, Sheba Devan, Venkat R. Subramanian, Ralph E. White

Faculty Publications

A macrohomogeneous model is presented for a porous electrode that includes coupled potential and concentration gradients with linear kinetics. The equations are solved to obtain an analytical expression for the impedance of a porous electrode. Complex plane plots are presented that illustrate two well-defined arcs: a kinetic arc and a diffusion arc with their time constants far apart. The effects of parameters such as exchange current density, porosity, diffusion coefficient, thickness, and interfacial area on the impedance spectra are presented. The usefulness of the analytical solution in investigating the effect of solution phase diffusion is also presented.

Go to article

A Steady-State Impedance Model For A Pemfc Cathode, Qingzhi Guo, Ralph E. White Jan 2004

A Steady-State Impedance Model For A Pemfc Cathode, Qingzhi Guo, Ralph E. White

Faculty Publications

A model for the simulation of the steady-state impedance response of a polymer electrolyte membrane fuel cell (PEMFC) cathode is presented. The catalyst layer of the electrode is assumed to consist of many flooded spherical agglomerate particles surrounded by a small volume fraction of gas pores. Stefan-Maxwell equations are used to describe the multicomponent gas-phase transport occurring in both the gas diffusion layer and the catalyst layer of the electrode. Liquid-phase diffusion of O2 is assumed to take place in the flooded agglomerate particles. Newman’s porous electrode theory is applied to determine over-potential distributions. © 2004 The Electrochemical Society. All …

Go to article

First Prev Next Last