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Faculty Publications

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Articles 2131 - 2160 of 3295

Full-Text Articles in Engineering

Gene Order Phylogeny And The Evolution Of Methanogens, Haiwei Luo, Zhiyi Sun, William Arndt, Jian Shi, Robert Friedman, Jijun Tang Jun 2009

Gene Order Phylogeny And The Evolution Of Methanogens, Haiwei Luo, Zhiyi Sun, William Arndt, Jian Shi, Robert Friedman, Jijun Tang

Faculty Publications

Methanogens are a phylogenetically diverse group belonging to Euryarchaeota. Previously, phylogenetic approaches using large datasets revealed that methanogens can be grouped into two classes, “Class I” and “Class II”. However, some deep relationships were not resolved. For instance, the monophyly of “Class I” methanogens, which consist of Methanopyrales, Methanobacteriales and Methanococcales, is disputable due to weak statistical support. In this study, we use MSOAR to identify common orthologous genes from eight methanogen species and a Thermococcale species (outgroup), and apply GRAPPA and FastME to compute distance-based gene order phylogeny. The gene order phylogeny supports two classes of methanogens, but it …


Probability Density Functions For Snir In Ds-Cdma, David W. Matolak Jun 2009

Probability Density Functions For Snir In Ds-Cdma, David W. Matolak

Faculty Publications

Analytical expressions for the probability density function of block-wise signal-to-noise-plus-interference ratio for both synchronous and asynchronous direct-sequence spread spectrum code-division multiple access systems are developed, for equal average energy signals on the Gaussian and Rayleigh flat fading channels. Using the standard Gaussian approximation for multi-user interference, accurate density approximations are obtained, which agree very well with computer simulation results.


Transdisciplinary Green Engineering Education At San José State University, Belle Wei, Patricia Backer Jun 2009

Transdisciplinary Green Engineering Education At San José State University, Belle Wei, Patricia Backer

Faculty Publications

Climate change is a pressing issue for the world today. There are an increasing number of technological by-products posing a threat to the stability and quality of the world environment. According to the United Nations’ Intergovernmental Panel on Climate Change (IPCC), global warming appears to be accelerating, resulting in higher increases in global temperature and higher rises in the sea level. To effectively address this problem, there is a need for transdisciplinary, transnational approaches, reflecting the complexity of the problem and the interdependence of people’s lives around the world. Consequently, the Davidson College of Engineering at San José State University …


Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain Jun 2009

Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain

Faculty Publications

This paper presents a new concept for aerial recovery of Micro Air Vehicles (ARMAVs) using a large mothership and a recovery drogue. The mothership drags a drogue attached to a cable and the drogue is controlled to match the flight patten of the MAV. This paper uses Gauss’s Principle to derive the dynamic model of the cable-drogue systems. A controllable drogue plays a key role in recovering MAVs in windy conditions. We develop a control approach for the drogue using its drag coefficient. Simulation results based on multilink cable-drogue systems present the feasibility of the aerial recovery concept and the …


Nondestructive Electromagnetic Material Characterization Using A Dual Waveguide Probe: A Full Wave Solution, Milo W. Hyde Iv, James W. Stewart, Michael J. Havrilla, William P. Baker, Edward Rothwell, Dennis P. Nyquist Jun 2009

Nondestructive Electromagnetic Material Characterization Using A Dual Waveguide Probe: A Full Wave Solution, Milo W. Hyde Iv, James W. Stewart, Michael J. Havrilla, William P. Baker, Edward Rothwell, Dennis P. Nyquist

Faculty Publications

A nondestructive technique for determining the complex permittivity and permeability of a perfect electric conductor backed magnetic shielding material using a dual waveguide probe is presented. The dual waveguide probe allows for the simultaneous collection of reflection and transmission coefficients which distinguishes it from single probe methods common in the literature. Theoretical development of these coefficients, which is accomplished through a coupled magnetic field integral equations formulation using Love's equivalence principle and solved via the method of moments (MOM), is discussed. Evaluation of the resulting MOM impedance matrix elements is performed using complex plane integration leading to enhanced computational efficiency …


Time Domain Equalizer Design Using Bit Error Rate Minimization For Uwb Systems, Syed Imtiaz Husain, Jinhong Yuan, Jian Zhang, Richard K. Martin May 2009

Time Domain Equalizer Design Using Bit Error Rate Minimization For Uwb Systems, Syed Imtiaz Husain, Jinhong Yuan, Jian Zhang, Richard K. Martin

Faculty Publications

Ultra-wideband (UWB) communication systems occupy huge bandwidths with very low power spectral densities. This feature makes the UWB channels highly rich in resolvable multipaths. To exploit the temporal diversity, the receiver is commonly implemented through a Rake. The aim to capture enough signal energy to maintain an acceptable output signal-to-noise ratio (SNR) dictates a very complicated Rake structure with a large number of fingers. Channel shortening or time domain equalizer (TEQ) can simplify the Rake receiver design by reducing the number of significant taps in the effective channel. In this paper, we first derive the bit error rate (BER) of …


Tobacco Mosaic Virus Templated Synthesis Of One Dimensional Inorganic-Polymer Hybrid Fibres, Jianhua Rong, Fiona Oberbeck, Xinnan Wang, Xiaodong Li, Jerry Oxsher, Zhongwei Niu, Qian Wang May 2009

Tobacco Mosaic Virus Templated Synthesis Of One Dimensional Inorganic-Polymer Hybrid Fibres, Jianhua Rong, Fiona Oberbeck, Xinnan Wang, Xiaodong Li, Jerry Oxsher, Zhongwei Niu, Qian Wang

Faculty Publications

Inorganic–polymer hybrid nanofibres were prepared by using a rod-like tobacco mosaic virus (TMV) as a template. With tetraethylorthosilicate (TEOS) as a precursor, long silica-coated TMVfibres were formed via a head-to-tail assembly, which showed a substantial increase of the elastic modulus. Furthermore, homogenous titania–TMV hybrid fibres could be prepared using polyaniline-coated TMV fibres as a template, which were used to form a composite film that was able to sense liquefied petroleum gases.


Parallel-Connected Solar Pv System To Address Partial And Rapidly Fluctuating Shadow Conditions, Lijun Gao, Roger A. Dougal, Shengyi Liu, Albena P. Iotova May 2009

Parallel-Connected Solar Pv System To Address Partial And Rapidly Fluctuating Shadow Conditions, Lijun Gao, Roger A. Dougal, Shengyi Liu, Albena P. Iotova

Faculty Publications

Solar photovoltaic (PV) arrays in portable applications are often subject to partial shading and rapid fluctuations of shading. In the usual series-connected wiring scheme, the residual energy generated by partially shaded cells either cannot be collected (if diode bypassed) or, worse, impedes collection of power from the remaining fully illuminated cells (if not bypassed). Rapid fluctuation of the shading pattern makes maximum power point (MPP) tracking difficult; generally, there will exist multiple local MPPs, and their values will change as rapidly as does the illumination. In this paper, a portable solar PV system that effectively eliminates both of the aforementioned …


Ultrasonic Drug Delivery To Tumors Via Stealth Liposomes, Peter Jones, Ghaleb A. Husseini, William G. Pitt, Beverly L. Roeder Apr 2009

Ultrasonic Drug Delivery To Tumors Via Stealth Liposomes, Peter Jones, Ghaleb A. Husseini, William G. Pitt, Beverly L. Roeder

Faculty Publications

Our research develops ultrasonically-controlled drug delivery systems. Previous micellar drug carriers released the drug upon ultrasonication. We have developed a liposomal drug carrier that is even more effective upon insonation in reducing tumors.


Barriers To Mitigation: A Pilot Study, James Lee, Crystal Paul, Guna Selvaduray Apr 2009

Barriers To Mitigation: A Pilot Study, James Lee, Crystal Paul, Guna Selvaduray

Faculty Publications

This pilot research was undertaken to discover barriers that prevent homeowners from mitigating earthquake hazards in their homes. There is a relatively significant body of literature on disaster mitigation, which is reviewed and summarized in this report. However, no studies address how these barriers may be overcome so that homeowners would be more proactive in mitigation. If the barriers can be identified, then future communications and policy actions that address these barriers can be taken, resulting in more widespread mitigation implementation that reduces the injury and damage potential that communities face, leading to a reduction in the post-disaster response requirement, …


Exploiting Matrix Symmetry To Improve Fpgaaccelerated Conjugate Gradient, Jason D. Bakos, Krishna K. Nagar Apr 2009

Exploiting Matrix Symmetry To Improve Fpgaaccelerated Conjugate Gradient, Jason D. Bakos, Krishna K. Nagar

Faculty Publications

In this paper we describe a new approach for accelerating the Conjugate Gradient (CG) method using an FPGA co-processor. As in previous approaches, our co-processor performs a double-precision sparse matrix-vector multiplication. However, our implementation doubles the amount of computation per unit of input data by exploiting the symmetry of the input matrix and computing the upper and lower triangle of the input matrix in parallel. Using a Virtex-2 Pro 100 FPGA, we have achieved an observed computational throughput of 1155 MFLOPS.


Payload Directed Flight Of Miniature Air Vehicles, Randal W. Beard, Clark Taylor, Jeff Saunders, Ryan Holt, Timothy W. Mclain Apr 2009

Payload Directed Flight Of Miniature Air Vehicles, Randal W. Beard, Clark Taylor, Jeff Saunders, Ryan Holt, Timothy W. Mclain

Faculty Publications

This paper describes three applications of payload directed flight using miniature air vehicles: vision-based road following, vision-based target tracking, and vision-based mapping. A general overview of each application is given, followed by simulation and flight-test results. Results demonstrate the viability of utilizing electo-optical video imagery to directly control the air vehicle flight path to enhance performance relative to the sensing objective.


La0.85Sr0.15Mno3− Infiltrated Y0.5Bi1.5O3 Cathodes For Intermediate-Temperature Solid Oxide Fuel Cells, Jiang Zhiyi, Changrong Xia, Fei Zhao, Fanglin Chen Mar 2009

La0.85Sr0.15Mno3− Infiltrated Y0.5Bi1.5O3 Cathodes For Intermediate-Temperature Solid Oxide Fuel Cells, Jiang Zhiyi, Changrong Xia, Fei Zhao, Fanglin Chen

Faculty Publications

Porous yttria-stabilized bismuth oxides (YSB) were investigated as the backbones for (LSM) infiltrated cathodes in intermediate-temperature solid oxide fuel cells. The cathodes were evaluated using anode-supported single cells with scandia-stabilized zirconia as the electrolytes. With humidified as the fuel, the cell showed peak power density of 0.33, 0.52, and at 650, 700, and , respectively. At , the cell polarization resistance was only , of the lowest value previously reported, indicating that YSB is a promising backbone for the LSM infiltrated cathode.


Sharing And Fusing Landmark Information In A Team Of Autonomous Robots, Damian M. Lyons Mar 2009

Sharing And Fusing Landmark Information In A Team Of Autonomous Robots, Damian M. Lyons

Faculty Publications

A team of robots working to explore and map a space may need to share information about landmarks so as register local maps and to plan effective exploration strategies. In this paper we investigate the use of spatial histograms (spatiograms) as a common representation for exchanging landmark information between robots. Each robot can use sonar, stereo, laser and image information to identify potential landmarks. The sonar, laser and stereo information provide the spatial dimension of the spatiogram in a landmark-centered coordinate frame while video provides the image information. We call the result a terrain spatiogram. This representation can be shared …


Mobility Handling In Mac For Wireless Ad Hoc Networks, Anjali Raja, Xiao Su Mar 2009

Mobility Handling In Mac For Wireless Ad Hoc Networks, Anjali Raja, Xiao Su

Faculty Publications

Wireless Sensor Networks (WSNs) are becoming popular in a wide variety of applications. In a WSN, sensor nodes can be static or mobile, depending on applications. Handling mobility in a sensor network can pose interesting challenges in sensor protocol design, and special algorithms are needed to adapt to mobility in the network. In this paper, we survey the current state of art in handling mobility in sensor networks. We first study how mobility affects the design of different layers in the sensor network architecture, and then take a closer look at mobility handling in the MAC layer. We also describe …


Deep Levels In Gate And Gate:In Crystals Investigated By Deep-Level Transient Spectroscopy And Photoluminescence, Y. Cui, D. D. Caudel, P. Bhattacharya, A. Burger, K. C. Mandal, D. Johnstone, S. A. Payne Mar 2009

Deep Levels In Gate And Gate:In Crystals Investigated By Deep-Level Transient Spectroscopy And Photoluminescence, Y. Cui, D. D. Caudel, P. Bhattacharya, A. Burger, K. C. Mandal, D. Johnstone, S. A. Payne

Faculty Publications

No abstract provided.


Low Temperature, Organic-Free Synthesis Of Ba3B6O9(Oh)6 Nanorods And Ss-Bab2O4 Nanospindles, Rui Li, Xinyoung Tao, Xiaodong Li Feb 2009

Low Temperature, Organic-Free Synthesis Of Ba3B6O9(Oh)6 Nanorods And Ss-Bab2O4 Nanospindles, Rui Li, Xinyoung Tao, Xiaodong Li

Faculty Publications

Using a low temperature, organic-free hydrothermal technique, single-crystalline barium polyborate Ba3B6O9(OH)6 (BBOH) nanorods were synthesized. It was found that β-BaB2O4(BBO) nanospindles can be achieved by annealing the BBOH nanorods at a relatively low temperature of 810 °C. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize these nanomaterials. The formation mechanisms are discussed in conjunction with the crystallographic characteristics and surface energy of the BBOH nanorods and BBO nanospindles. UV-vis absorption spectra demonstrated that both BBOH nanorods and BBO nanospindles are …


Unveiling The Formation Mechanism Of Pseudo-Single-Crystal Aragonite Platelets In Nacre, Xiaodong Li, Zaiwang Huang Feb 2009

Unveiling The Formation Mechanism Of Pseudo-Single-Crystal Aragonite Platelets In Nacre, Xiaodong Li, Zaiwang Huang

Faculty Publications

We demonstrate direct evidence that a single-crystal-like aragonite platelet is essentially assembled with aragonite nanoparticles. The aragonite nanoparticles are readily oriented and assembled into pseudo-single-crystal aragonite platelets via screw dislocation and amorphous aggregation, which are two dominant mediating mechanisms between nanoparticles during biomineralization. These findings will advance our understanding of nacre’s biomineralization process and provide additional design guidelines for developing biomimetic materials.


Correlating Threshold Power With Free-Space Bandwidth For Low-Directivity Antennas, Abu T.M. Sayem, Mark G. Douglas, Gernot Schmidt, Ben Petric, Mohammod Ali Feb 2009

Correlating Threshold Power With Free-Space Bandwidth For Low-Directivity Antennas, Abu T.M. Sayem, Mark G. Douglas, Gernot Schmidt, Ben Petric, Mohammod Ali

Faculty Publications

This paper develops a threshold power rationale that can be used to demonstrate inherent compliance for portable wireless devices with specific absorption rate (SAR) limits over the 300-6000-MHz frequency range. This is achieved first by understanding the relationship between basic antenna parameters (bandwidth, operating frequency, and distance to the body) and SAR. From this, an upper limit is determined for the power transmitted by a portable wireless device such that the SAR will not exceed the compliance limit. Based on the presented computational and measured data, an empirical formula is developed for the threshold power as a function of the …


Locating And Tracking Objects By Efficient Comparison Of Real And Predicted Synthetic Video Imagery, Damian M. Lyons, D. Paul Benjamin Jan 2009

Locating And Tracking Objects By Efficient Comparison Of Real And Predicted Synthetic Video Imagery, Damian M. Lyons, D. Paul Benjamin

Faculty Publications

A mobile robot moving in an environment in which there are other moving objects and active agents, some of which may represent threats and some of which may represent collaborators, needs to be able to reason about the potential future behaviors of those objects and agents. In this paper we present an approach to tracking targets with complex behavior, leveraging a 3D simulation engine to generate predicted imagery and comparing that against real imagery. We introduce an approach to compare real and simulated imagery and present results using this approach to locate and track objects with complex behaviors. In this …


Query Recommendations For Interactive Database Exploration, Gloria Chatzopoulou, Magdalini Eirinaki, Neoklis Polyzotis Jan 2009

Query Recommendations For Interactive Database Exploration, Gloria Chatzopoulou, Magdalini Eirinaki, Neoklis Polyzotis

Faculty Publications

Relational database systems are becoming increasingly popular in the scientific community to support the interactive exploration of large volumes of data. In this scenario, users employ a query interface (typically, a web-based client) to issue a series of SQL queries that aim to analyze the data and mine it for interesting information. First-time users, however, may not have the necessary knowledge to know where to start their exploration. Other times, users may simply overlook queries that retrieve important information. To assist users in this context, we draw inspiration from Web recommender systems and propose the use of personalized query recommendations. …


A Trade-Off Analysis Of Energy Detectors And Partitioned Search For Primary Detection, Birsen Sirkeci-Mergen, Vishal Sawant, Robert H. Morelos-Zaragoza Jan 2009

A Trade-Off Analysis Of Energy Detectors And Partitioned Search For Primary Detection, Birsen Sirkeci-Mergen, Vishal Sawant, Robert H. Morelos-Zaragoza

Faculty Publications

Cognitive radios aim to coexist in the unused spectrum bands which are licensed to primary users without harming the primary transmission/reception. For a cognitive radio, it is important to detect the band in which the primary is operating as fast as possible and with high reliability in order to adapt its transmission. In this work, we propose P-partitioning method in combination with energy detectors for the search of the band that the primary user is operating. In the P-partitioning method, the spectrum bands are categorized into P groups and the group that the primary band belongs to is detected in …


An Adaptive Adjacent Channel Interference Cancellation Technique, Robert H. Morelos-Zaragoza, Shobha Kuruba Jan 2009

An Adaptive Adjacent Channel Interference Cancellation Technique, Robert H. Morelos-Zaragoza, Shobha Kuruba

Faculty Publications

In this paper, an adaptive adjacent channel interference (ACI) technique is proposed. Results for BPSK modulation with rectangular and square-root raised-cosine pulse shaping, under AWGN conditions, are obtained showing the proposed method to be effective in improving performance under high levels of interference. Basically, the idea is to send pilot signals and then to use them in estimating the amount of ACI in the frequency domain. The estimated spectral error is used to modify tap weights of an adaptive frequency-domain filter. Our simulation results reported suggest that ACI can be effectively reduced with the proposed technique. At the system level, …


Reduction Of Model Order Based On Proper Orthogonal Decomposition For Lithium-Ion Battery Simulations, Long Cai, Ralph E. White Jan 2009

Reduction Of Model Order Based On Proper Orthogonal Decomposition For Lithium-Ion Battery Simulations, Long Cai, Ralph E. White

Faculty Publications

A reduced-order model (ROM) is developed using proper orthogonal decomposition (POD) for a physics-based lithium-ion battery model. The methodology to obtain the proper orthogonal modes and to analyze their optimality is included. The POD-based ROM for a lithium-ion battery is used to simulate a charge/discharge process and the behavior of a battery pack. Compared to the physics-based model, the computational time to solve the ROM is significantly less, and the two models show excellent agreement.


Effect Of Water Transport On The Production Of Hydrogen And Sulfuric Acid In A Pem Electrolyzer, John A. Staser, John W. Weidner Jan 2009

Effect Of Water Transport On The Production Of Hydrogen And Sulfuric Acid In A Pem Electrolyzer, John A. Staser, John W. Weidner

Faculty Publications

The thermochemical cycle involving the interconversion between sulfur dioxide and sulfuric acid is a promising method for efficient, large-scale production of hydrogen. A key step in the process is the oxidation of sulfur dioxide to sulfuric acid in an electrolyzer. Gaseous SO2 fed to a proton exchange membrane (PEM) electrolyzer was previously investigated and was shown to be a promising system for the electrolysis step. A critical factor in the performance of this gas-fed electrolyzer is the management of water since it: (i) is needed as a reactant, (ii) determines the product sulfuric acid concentration, …


Electrochemical Removal Of Carbon Monoxide In Reformate Hydrogen For Fueling Proton Exchange Membrane Fuel Cells, Sivagaminathan Balasubramanian, Charles E. Holland, John W. Weidner Jan 2009

Electrochemical Removal Of Carbon Monoxide In Reformate Hydrogen For Fueling Proton Exchange Membrane Fuel Cells, Sivagaminathan Balasubramanian, Charles E. Holland, John W. Weidner

Faculty Publications

A twin-cell electrochemical filter is demonstrated to reduce the CO concentration in reformate hydrogen. In this design, the potential and gas flow are switched between the two filter cells so that alternative CO adsorption and oxidation occur in each cell while providing a continuous flow of H2 to a fuel cell. The effects of filter switching time and applied potential on the CO concentration of gas exiting the filter are presented here for a CO concentration of 1000 ppm in nitrogen flowing at 100 cm3/min. The parasitic loss of hydrogen from a corresponding reformate stream was estimated to be 1.5%.


Agents And Service-Oriented Computing For Autonomic Computing: A Research Agenda, Frances M.T. Brazier, Jeffrey O. Kephart, H. Van Dyke Parunak, Michael N. Huhns Jan 2009

Agents And Service-Oriented Computing For Autonomic Computing: A Research Agenda, Frances M.T. Brazier, Jeffrey O. Kephart, H. Van Dyke Parunak, Michael N. Huhns

Faculty Publications

Autonomic computing is the solution proposed to cope with the complexity of today's computing environments. Self-management, an important element of autonomic computing, is also characteristic of single and multiagent systems, as well as systems based on service-oriented architectures. Combining these technologies can be profitable for all - in particular, for the development of autonomic computing systems.


An Infrared Imaging Method For High-Throughput Combinatorial Investigation Of Hydrogenation-Dehydrogenation And New Phase Formation Of Thin Films, H. Oguchi, Jason R. Hattrick-Simpers, I. Takeuchi, E. J. Heilweil, L. A. Bendersky Jan 2009

An Infrared Imaging Method For High-Throughput Combinatorial Investigation Of Hydrogenation-Dehydrogenation And New Phase Formation Of Thin Films, H. Oguchi, Jason R. Hattrick-Simpers, I. Takeuchi, E. J. Heilweil, L. A. Bendersky

Faculty Publications

We have developed an infrared imaging setup enabling in situ infrared images to be acquired, and expanded on capabilities of an infrared imaging as a high-throughput screening technique, determination of a critical thickness of a Pd capping layer which significantly blocks infrared emission from below, enhancement of sensitivity to hydrogenation and dehydrogenation by normalizing raw infrared intensity of a Mg thin film to an inert reference, rapid and systematic screening of hydrogenation and dehydrogenation properties of a Mg–Ni composition spread covered by a thickness gradient Pd capping layer, and detection of formation of a Mg2Si phase in a …


A Miniature Spiral Diversity Antenna System With High Overall Gain Coverage And Low Sar, Abu T.M. Sayem, Sadia Khan, Mohammod Ali Jan 2009

A Miniature Spiral Diversity Antenna System With High Overall Gain Coverage And Low Sar, Abu T.M. Sayem, Sadia Khan, Mohammod Ali

Faculty Publications

A miniature spiral diversity antenna system operating at 1.85 GHz is proposed. Two 10 mm 6.25 mm antennas were placed at two corners of a printed circuit board at a height of 7 mm from the ground plane. Each antenna achieves nearly 7% bandwidth within 6 dB return loss. The mutual coupling between the two antennas is less than 10 dB. The proposed diversity antenna scheme exhibits high overall gain performance in all three principal planes compared to a single antenna solution. Computed specific absorption rate (SAR) data against a specific anthropomorphic mannequin (SaM) phantom and a hand model show …


Inhomogeneous Degradation Of Polymer Electrolyte Membrane In Pem Fuel Cells, Xinyu Huang, Wonseok Yoon Jan 2009

Inhomogeneous Degradation Of Polymer Electrolyte Membrane In Pem Fuel Cells, Xinyu Huang, Wonseok Yoon

Faculty Publications

Membrane durability is one of the technical barriers for the commercialization of polymer electrolyte membrane (PEM) fuel cells. Membrane embrittlement (a form of mechanical weakening) can lead to the frequently observed “sudden death” behavior of PEM fuel cells. It is the objective of this study to explore the fundamental mechanisms of the mechanical weakening of perfluorosulfonic acid (PFSA) based electrolyte membranes during the accelerated degradation test.