Electrical and Computer Engineering Commons^™

Fuel Cells Reactor For Chemicals And Electric Energy Cogeneration, Zhi-Lin Heng, Xiao-Zi Yuan, Yi-Mei Yin, Zi-Feng Ma

Journal of Electrochemistry

As an energy conversion device, fuel cells can efficiently convert chemical energy into electrical energy. With the developing of technology, it is used as a reactor to conduct the synthesis of high value-added chemicals while generating electrical energy. Having benefits such as mild reaction conditions, controllability of the reaction process, high selectivity of the product, as well as high efficiency of energy utilization, it is widely used in many fields such as preparation of high value-added industrial products, gas separation, water treatment, etc. This paper introduces the current trends and statuses of fuel cell reactors in the cogeneration of chemicals …

Durability Performance Of The High-Power Fuel Cell System, Ke-Yong Wang, Wei-Yu Shi, Ren-Fang Wang, Jia Liu, Zhong-Jun Hou

Journal of Electrochemistry

Fuel cell durability is the crucial challenge in fuel cell vehicle, and the lifetime of more than 5000 hours is believed to be necessary for vehicle application. Few works on durability test of the full fuel cell system have been reported. In this work, the long lifetime HySYS-30 fuel cell system was developed in Sunrise Power based on the improved MEA durability and system control strategy. The durability performance of the system was investigated under vehicle duty cycle for more than 6000 hours, and only 8.1% performance loss was observed, implying that the durability of HySYS-30 fuel cell system could …

A Review Of Proton Exchange Membrane Fuel Cell Catalyst Layer By Electrospinning, Yong Liu, Han Ding, De-Chun Si, Jie Peng, Jian-Bo Zhang

Journal of Electrochemistry

The limitation of catalyst layer for proton exchange membrane fuel cell (PEMFC) in cost, durability and performance constitutes the bottleneck for the commercialization of fuel cell vehicles. Electrospun catalyst layer, with high catalyst utilization, increased triple phase boundary (TPB) and triple phase channel (TPC), has been developed by many researchers. This paper reviews the research progress in the electrospun catalyst layer for PEMFC, combined with the author’s work. Firstly, the development progress of catalyst layer is summarized, and the catalyst layer is classified and analyzed based on its fabrication method and structure character. Next, the fabrication process, physical property characterization, …

Stabilization Strategies Of Pt Catalysts Forproton Exchange Membrane Fuel Cells, Da-Ping He, Shi-Chun Mu

Journal of Electrochemistry

The low service lifetime of proton exchange membrane fuel cells (PEMFCs) is the main bottleneck for their commercial applications. One of the main factors is that the expensive metal Pt catalyst is easy to degradation under the harsh working environment of PEMFC (such as variable voltage, strong acidity, gas-liquid two-phase flow), which leads to the inevitable decay of the catalytic performance, thus, seriously restricting the lifetime of PEMFC. Therefore, the electrochemical stability of Pt-based electrocatalysts has become an important and hot topic to improve the PEMFC lifetime. In this paper, we review the recent development in enhancing the stability of …

The Pilot Application Of Electrochemical Impedance Spectroscopy On Dynamic Proton Exchange Membrane Fuel Cell, Jian-Wei Guo, Jian-Long Wang

Journal of Electrochemistry

By analyzing Electrochemical Impedance Spectroscopy (EIS) in applications of dynamic proton exchange membrane fuel cell (PEMFC), bottlenecks which restrict EIS tool development have been pointed out in this paper. Though the high-frequency resistance in EIS is largely accepted as cell inner-resistance, this can only be applied for cell with low current. The low-frequency resistance is difficult to be realized due to its relation with mass transfer. Furthermore, the improved Randles equivalent circuits are built up preliminarily, thus, penetrating into studies for mass transfer reaction, cell operation/degeneration, and high temperature fuel cell. Inspiringly, EIS is becoming an analyzing tool for stack …

Morphological Control Of Ptcu2 Octahedron And Oxygen Reduction Electrocatalytic Performance Of Ptcu For Fuel Cell, Long-Sheng Cao, Lei Wan, Zhi-Gang Shao, Hong-Mei Yu, Ming Hou, Bao-Lian Yi

Journal of Electrochemistry

Platinum acetylacetonate (Pt(acac)₂) and copper acetylacetonate (Cu(acac)₂) were co-reduced to prepare PtCu₂ octahedron alloy catalyst in N,N-dimethylformamiade by solvothermal method. The PtCu₂ showed lattice compression, and high ratio of non-oxidized Pt with high electronic binding energy. All those structural features contributed to weak adsorption strength of oxygen species on Pt and lower d-band centre position. The influence of structure-directing agent on morphology of PtCu alloy was systematically studied. In the half cell test, as a result of the uniform morphology and regular octahedron of PtCu₂ formed, the mass activity and area specific activity …

Effects Of So2 In Air On Performance Of Direct Methanol Fuel Cell, Bin Qin, Fen-Ning Jing, Xue-Jing Sun, Gong-Quan Sun, Hai Sun

Journal of Electrochemistry

Direct methanol fuel cells (DMFC) generally use oxygen as an oxidant. Contaminants such as sulfides and nitrides in the air can affect the performance of the DMFC. In this work, the effects of SO₂ on the performance of DMFC were investigated and the mechanism of poisoning was analyzed, by means of constant current discharge curve, polarization performance curve, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the CV scan, the permeated methanol was oxidized at a low potential to eliminate its effect on the SO₂ poisoning behavior test. The results showed that the SO₂ poisoning resulted …

Facile Synthesis Of Pt-Cu Alloy Nanodendrites As High-Performance Electrocatalysts For Oxygen Reduction Reaction, Liu-Xuan Luo, Guang-Hua Wei, Shui-Yun Shen, Feng-Juan Zhu, Chang-Chun Ke, Xiao-Hui Yan, Jun-Liang Zhang

Journal of Electrochemistry

Structures and compositions have significant effects on the catalytic properties of nanomaterials. Herein, a facile etching-based method was employed to synthesize Pt-Cu nanodendrites (NDs) with uniform and homogeneous alloy structures for enhancing oxygen reduction reaction (ORR). The formation of dendritic morphology was ascribed to the etching effect caused by the oxidative etchants of the Br^-/O₂ pair. The atomic ratio of Pt/Cu in Pt-Cu NDs could be easily tuned by altering the ratio of the Pt/Cu precursors, without deteriorating the dendritic morphology. The most active carbon-supported Pt₁Cu₁ NDs (Pt₁Cu₁ NDs/C) exhibited the …

Acid Treated Carbon As Anodic Electrocatalysts Toward Direct Ascorbic Acid Alkaline Membrane Fuel Cells, He-Mu Chen, Chen-Xi Qiu, Yuan-Yuan Cong, Hui-Yuan Liu, Zi-Hui Zhai, Yu-Jiang Song

Journal of Electrochemistry

In order to improve the hydrophilicity and electrocatalytic activity, commercial carbon black (BP 2000) was subjected to acid treatment to obtain acid-treated carbon (ATC). The generation of rich oxygen-containing groups on the surface of the ATC was proved by X-ray photoelectron spectra (XPS), Fourier transform-infra red spectra (FTIR), thermogravimetric analysis (TG) and contact angle measurement. UV-vis spectra were firstly recorded to calculate activation energy (Ea) of ascorbic acid (AA) chemical oxidation in alkaline conditions by oxygen in air and the Ea value was determined to be 37.1 kJ·mol^-1. Additionally, electrochemical impedance spectra (EIS) were used to evaluate unprecedented …

Pd/C Catalysts For Co2 Electroreduction To Co:Pd Loading Effect, Dun-Feng Gao, Cheng-Cheng Yan, Guo-Xiong Wang, Xin-He Bao

Journal of Electrochemistry

Nanostructured heterogeneous catalysts have been widely used in the electrochemical carbon dioxide (CO₂) reduction reaction (CO₂RR), which can simultaneously achieve the electrocatalytic conversion of CO₂ to fuels and the storage of renewable energy sources. Carbon supported palladium nanoparticles (Pd/C) catalysts have been previously reported to show excellent CO₂RR performance. However, the crucial role of the metal loading in supported electrocatalysts has been rarely reported. In this work, we study the Pd loading effect on the structure of Pd/C catalysts as well as their activity and selectivity of CO₂RR to CO. The …

Caging Porous Co-N-C Nanocomposites In 3d Graphene As Active And Aggregation-Resistant Electrocatalyst For Oxygen Reduction Reaction, Lu-Yang Xiu, Meng-Zhou Yu, Peng-Ju Yang, Zhi-Yu Wang, Jie-Shan Qiu

Journal of Electrochemistry

Oxygen reduction reaction (ORR) is the cornerstone reaction of many renewable energy technologies such as fuel cells and rechargeable metal-air batteries. The Pt-based electrocatalysts exhibit the highest activity toward ORR, but their large implementation is greatly prohibiting by unaffordable cost and inferior durability. During electrode manufacturing and electrochemical reaction, severe aggregation of catalyst nanoparticles induced by size effect further limits the operational performance of electrocatalysts. We report a new strategy for fabrication of active and aggregation-resistant ORR electrocatalyst by caging metal-organic frameworks derived Co-N-C nanocomposites in permeable and porous 3D graphene cages via sprayed drying the mixed colloids of ZIF-67 …

Comparison Of Switched Reluctance Motor And Double Stator Switched Reluctance Motor, Nirdesh Neupane

LSU New Orleans Theses and Dissertations

This thesis is concerned with the design and analysis of Switched Reluctance Motor (SRM) and its improved structure Double Stator Switched Reluctance Motor (DSSRM). Three configurations of SRM viz. Inner Stator, Outer stator and Double Stator are designed and simulated in ANSYS Maxwell Suite. Design parameters are chosen by aiming optimum performance of motor after literature review and analytical study of the motor. SRM is not a line start machine, so power converter circuit is required to excite the motor. Without proper switching of current, desired torque is not obtained in SRM. The converter circuit and switching unit is built …

Performance Optimization Of The Differential Protection Schemes, Monir Hossain

LSU New Orleans Theses and Dissertations

Current differential protection principle is superior in terms of sensitivity and speed of operation in comparison with other protection principle used in power systems. From the last five decades, various current differential protection schemes are widely used to protect busbars, transformers, and short-transmission lines. The deployment of high capacity microwave and optical fiber technologies redefined

the line protection systems by facilitating the use of current differential protection schemes for long transmission lines. The common application issue of these schemes is mis-operation due to current transformer (CT) saturation during close-in external faults. Moreover, transformer differential protection schemes face mis-trip due to …

2018 Fall Engr333 Project Final Report (Section A), 2018 Fall Engr333 Section A

ENGR 333

Calvin College currently spends 2.35 million dollars on energy every year. Physical Plant is under pressure to reduce the amount of energy that Calvin purchases from the electrical grid since the college is facing many budget constraints. In addition, President Le Roy signed the President’s Carbon Commitment to achieve carbon neutrality by 2057. With this need to save money on energy and reduce the college’s carbon footprint, the objective of this project was to determine the largest possible reduction in Calvin’s annual energy costs given a five-million-dollar investment in renewable energy.

2018 Fall Engr333 Project Final Report (Section B), Alexander Cooper, Katie Diekema, Grace Fasipe, Daniella Sugijanto, Alec Dejonge, Timothy Dykhuis, Breanna Kooiman, Samuel Olson, Brennan Boice, Tyler Gustman, Daniel Norton, Christopher Vanwhye, Robert Capozzoli, Jared Minderhoud, Clark Richeson, Nathan Schuyten

ENGR 333

What is the largest possible reduction in Calvin College’s annual energy costs from a $5M initial investment in renewable energy? Renewable energy systems are essential for Calvin College to reduce greenhouse gas emissions and achieve carbon neutrality to meet the Carbon Commitment that President Le Roy signed in December 2017. Also, a significant cost reduction could be a positive result of transitioning to renewable energy sources such as geothermal, wind, solar, and biomass. Four renewable energy sources were studied throughout the semester to determine a feasible renewable energy plan for Calvin with a $5M investment.

Noise And Gain Characterization Of Interband Cascade Infrared Photodetectors, Eli A. Garduño

Electrical and Computer Engineering ETDs

Infrared (IR) detectors are an enabling technology for a broad and growing list of applications including gas detection, night vision, and space-based missile warning. There are ongoing efforts in IR detector research to explore the potential of new material systems and energy band structures in addition to continuously improving their sensitivity through increasing their quantum efficiency and lowering their dark current and noise. This dissertation examines an emerging class of IR detectors known as Interband Cascade Infrared Photodetectors (ICIPs).

ICIPs contain multiple regions to facilitate the collection of photogenerated electrons and to limit unwanted dark current. Theory regarding their performance …

Optical Micro-Seismometer Based On Evanescent Field Perturbation Of Whispering Gallery Modes, Jaime Da Silva

Mechanical Engineering Research Theses and Dissertations

This thesis proposes a light-weight, compact, and accurate optical micro-seismometer that could be used in many applications, such as planetary exploration. The sensor proposed here is based on the principle of whispering gallery optical mode (WGM) resonance shifts of a dielectric micro-resonator due to disturbances of its evanescent field. The micro-seismometer could be used in place of the traditional bulky seismometers. The design of a waveguide-resonator and mechanical structure to disturb the evanescent field are presented. A proof-of-concept a seismometer model that uses a 5µm ring resonator is numerically tested with actual seismic data. The results show that a WGM-based …

A Distributed Real-Time Short-Term Solar Irradiation Forecasting Network For Photovoltaic Systems, Michael Adelbert Gacusan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solar irradiation forecasting is essential for PV connected electrical grids to maintain reliability, stability, and effective matching of real-time demand to power distribution. This research paper develops and evaluates proposed forecasting methods using wireless sensor networks. Each node of the network is capable of monitoring illuminance data and communicate it through RF and/or WiFi. The nodes are calibrated with respect to irradiance data from an industry-standard pyranometer. Power consumption of each node type is also collected at different operating states. The proposed sensor network can estimate a cloud motion vector or a cloud shadow’s speed and direction from the data …

Accurate Vehicle Detection Using Multi-Camera Data Fusion And Machine Learning, Hao Wu

Electrical Engineering Theses and Dissertations

Computer-vision methods have recently been extensively used in intelligent transportation systems for vehicle detection. However, the detection of severely occluded or partially observed vehicles due to the limited camera fields of view remains a significant challenge. This paper presents a multi-camera vehicle detection system that significantly improves the detection performance under occlusion conditions. The key elements of the proposed method include a novel multi-view region proposal network that localizes the candidate vehicles on the ground plane. We also infer the vehicle occupancies by leveraging multi-view cross-camera context. Experiments are conducted on a dataset captured from a roadway in Richardson, TX, …

Basis Vector Model Method For Proton Stopping Power Estimation Using Dual-Energy Computed Tomography, Shuangyue Zhang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Accurate estimation of the proton stopping power ratio (SPR) is important for treatment planning and dose prediction for proton beam therapy. The state-of-the-art clinical practice for estimating patient-specific SPR distributions is the stoichiometric calibration method using single-energy computed tomography (SECT) images, which in principle may introduce large intrinsic uncertainties into estimation results. One major factor that limits the performance of SECT-based methods is the Hounsfield unit (HU) degeneracy in the presence of tissue composition variations. Dual-energy computed tomography (DECT) has shown the potential of reducing uncertainties in proton SPR prediction via scanning the patient with two different source energy spectra. …

Optimal Placement Of Distributed Energy Storage Systems In Distribution Networks Using Artificial Bee Colony Algorithm, Choton K. Das, Octavian Bass, Ganesh Kothapalli, Thair S. Mahmoud, Daryoush Habibi

Research outputs 2014 to 2021

The deployment of utility-scale energy storage systems (ESSs) can be a significant avenue for improving the performance of distribution networks. An optimally placed ESS can reduce power losses and line loading, mitigate peak network demand, improve voltage profile, and in some cases contribute to the network fault level diagnosis. This paper proposes a strategy for optimal placement of distributed ESSs in distribution networks to minimize voltage deviation, line loading, and power losses. The optimal placement of distributed ESSs is investigated in a medium voltage IEEE-33 bus distribution system, which is influenced by a high penetration of renewable (solar and wind) …

Analysis And Design Of Analog Front-End Circuitry For Avalanche Photodiodes (Apd) And Silicon Photo-Multipliers (Sipm) In Time-Of-Flight Applications, Vikas Vinayaka

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis reports the analysis and design of analog front-end circuitry for reading out signals from avalanche photodiodes (APD) or silicon photomultiplier (SiPM) in time-of-flight (ToF) applications. An integrated circuit was designed using AMS SiGe 0.35 um BiCMOS process. The chip measured 2 mm x 2 mm (2000 umx2000 um). The chip mainly contains the following circuits: an APD with photoactive area measuring 24 umx24 um, an SiPM with 8x8 APDs with 236 k ohm quench resistors, a transimpedance amplifier (TIA), a comparator and a R-2R digital to analog converter (DAC). The TIA is based on the shunt-shunt feedback topology. …

Nanopower Analog Frontends For Cyber-Physical Systems, Kenji Aono

McKelvey School of Engineering Graduate Student Theses & Dissertations

In a world that is increasingly dominated by advances made in digital systems, this work will explore the exploiting of naturally occurring physical phenomena to pave the way towards a self-powered sensor for Cyber-Physical Systems (CPS). In general, a sensor frontend can be broken up into a handful of basic stages: transduction, filtering, energy conversion, measurement, and interfacing. One analog artifact that was investigated for filtering was the physical phenomenon of hysteresis induced in current-mode biquads driven near or at their saturation limit. Known as jump resonance, this analog construct facilitates a higher quality factor to be brought about without …

Design And Analysis Of First And Second Order K-Delta-1-Sigma Modulators In Multiple Fabrication Processes, Shada Sharif

UNLV Theses, Dissertations, Professional Papers, and Capstones

Analog to digital converters (ADC) are an important category of electronic circuits that are required in order to convert real-world analog signals into the digital domain. One of the main trade-offs in ADC design is between data conversion speed and resolution. Delta Sigma ADCs are commonly used for high precision data conversion of low bandwidth signals such as those found in audio, industrial and biomedical applications. A major disadvantage of traditional Delta Sigma ADC architectures is that they have limited signal bandwidth and are not suited for high speed applications such as communication systems. The continuous time K-Delta-1-Sigma (KD1S) modulator …

Variable Transition Time Inverters In A Digital Delay Line With Analog Storage For Processing Fast Signals And Pulses, James Kenton Mellott

UNLV Theses, Dissertations, Professional Papers, and Capstones

As the electronics industry moves forward there is an increasing need to process information faster and more accurately. High speed signals are used in scientific instrumentation, range finding devices, radar applications, and electro-optical interfaces. High-speed state of the art analog-to-digital converters are required to process these signals in real time. High frequency signals or very fast pulses are not able to be processed accurately due to either Nyquist-rate limitations or practical power consumption limits. For applications where signals are transient in nature and design size and power consumption are major factors, the proposed Variable Fast Transient Digitizer (VFTD) will be …

High Speed Fast Transient Digitizer Design And Simulation, Eric Clark Monahan

UNLV Theses, Dissertations, Professional Papers, and Capstones

In microelectronics, analog-to-digital converters (ADCs) are used as interfaces to convert analog inputs into discrete time or digital values that can be read via microcontrollers. As speed requirements and processing times in electronics continue to increase, high speed ADCs are increasingly critical components in the design of application-specific integrated circuits (ASICs). However, high speed ADCs introduce quantization error and are inefficient relative to size, cost, and power dissipation when compared to a High Speed Fast Transient Digitizer (HSFTD).

This thesis presents the design, layout, and simulation of a HSFTD designed to sample, in time at a fast rate, a high-speed …

Design, Layout, And Testing Of Sige Apds Fabricated In A Bicmos Process, Dane Laurence Gentry

UNLV Theses, Dissertations, Professional Papers, and Capstones

This Thesis is concerned with the design, layout, and testing of avalanche photodiodes (APDs). APDs are a type of photodetector and, thus, convert light signals into electrical signals (current or voltage). APDs can be fabricated using silicon (Si). In this Thesis, however, three integrated circuit (IC) chips containing various silicon-germanium (SiGe) APDs with different sizes, structures, and geometries were designed, laid out, and fabricated using the Austriamicrosystems (AMS) 0.35μm SiGe BiCMOS (S35) process. This was done in order to compare SiGe APDs to Si only APDs and investigate the hypothesis that SiGe APDs are capable of detecting longer wavelengths than …

Extraction Of Vital Signs Using Real Time Video Analysis For Neonatal Monitoring, Bhushan Lohani

Electrical Engineering Theses

Video data is now commonly used for analysis in surveillance, security, medical and many other fields. The development of low cost but high-quality portable cameras has contributed significantly to this trend. One such trend includes non-invasive vital statistics monitoring of infants in Neonatal Intensive Care Units (NICU). National Center for Health Statistics Publications has reported a high infant death rate (23,215 in 2014). This statistic has drawn the interest of health system professionals. Due to occurrence of conditions like bradycardia, apnea and hypoxia, these preterm infants are kept in an NICU for constant monitoring. One of the problems faced at …

Structure-Mediated Excitation Of Air Plasma And Silicon Plasma Expansion In Femtosecond Laser Pulses Ablation, Qingsong Wang, Lan Jiang, Changji Pan, Weina Han, Guoyan Wang, Feifei Wang, Kaihu Zhang, Ming Li, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number, which in turn significantly affects successive laser-material interactions. By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy, here we present direct visualization of the excitation of air plasma induced by the reflected laser during the second pulse irradiation. The interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction, showing anisotropic expansion dynamics in different directions. We further demonstrate the vanishing of air plasma as the pulse number …

2018 Fall Engr333 Poster, Alexander Cooper, Katie Diekema, Grace Fasipe, Daniella Sugijanto, Alec Dejonge, Timothy Dykhuis, Breanna Kooiman, Samuel Olson, Brennan Boice, Tyler Gustman, Daniel Norton, Christopher Vanwhye, Robert Capozzoli, Jared Minderhoud, Clark Richeson, Nathan Schuyten, 2018 Fall Engr333 Section A

ENGR 333

• $158k initial investment in Geothermal systems for various Calvin-owned residential buildings
• $3.34M initial investment in solar panels for Calvin’s rooftops
• The overall savings would be $233,850 per year
• Emissions would be reduced by 864 tons of CO2 emissions per year
• The recommended investment would be fully paid back in 11-15 years