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Articles 2551 - 2580 of 8897

Full-Text Articles in Physical Sciences and Mathematics

Synthesis Of Keggin Polyoxometalates Modified Carbon Paste Electrode As A Sensor For Dopamine Detection, Peng-Fei Dong, Na Li, Hai-Yan Zhao, Min Cui, Cong Zhang, Ju-Jie Ren, Xue-Ping Ji Oct 2018

Synthesis Of Keggin Polyoxometalates Modified Carbon Paste Electrode As A Sensor For Dopamine Detection, Peng-Fei Dong, Na Li, Hai-Yan Zhao, Min Cui, Cong Zhang, Ju-Jie Ren, Xue-Ping Ji

Journal of Electrochemistry

Polyoxometalates, a class of anionic clusters with structure diversity and size variability, make them very attractive in many fields such as electrochemistry, catalysis and medicine. The Co(C15N6H12)2[PW12O38]·5H2O(Co[PW12O38]) modified carbon paste electrode was prepared in this work, and its electrochemical performances as the sensor for dopamine detection were characterized with electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry. The preparation conditions and test conditions were optimized respectively. Under the optimized conditions, the POMs modified carbon paste electrode exhibited good selectivity and sensitivity …


Electrical Characteristics Of A Balloon-Borne Radiation Instrument, Elena Pradhan, Jared Fuchs Oct 2018

Electrical Characteristics Of A Balloon-Borne Radiation Instrument, Elena Pradhan, Jared Fuchs

Von Braun Symposium Student Posters

No abstract provided.


Optical Wireless Data Center Networks, Abdelbaset S. Hamza Oct 2018

Optical Wireless Data Center Networks, Abdelbaset S. Hamza

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Bandwidth and computation-intensive Big Data applications in disciplines like social media, bio- and nano-informatics, Internet-of-Things (IoT), and real-time analytics, are pushing existing access and core (backbone) networks as well as Data Center Networks (DCNs) to their limits. Next generation DCNs must support continuously increasing network traffic while satisfying minimum performance requirements of latency, reliability, flexibility and scalability. Therefore, a larger number of cables (i.e., copper-cables and fiber optics) may be required in conventional wired DCNs. In addition to limiting the possible topologies, large number of cables may result into design and development problems related to wire ducting and maintenance, heat …


Signal Flow Graph Approach To Efficient Dst I-Iv Algorithms, Sirani M. Perera Oct 2018

Signal Flow Graph Approach To Efficient Dst I-Iv Algorithms, Sirani M. Perera

Sirani Mututhanthrige Perera

In this paper, fast and efficient discrete sine transformation (DST) algorithms are presented based on the factorization of sparse, scaled orthogonal, rotation, rotation-reflection, and butterfly matrices. These algorithms are completely recursive and solely based on DST I-IV. The presented algorithms have low arithmetic cost compared to the known fast DST algorithms. Furthermore, the language of signal flow graph representation of digital structures is used to describe these efficient and recursive DST algorithms having (n􀀀1) points signal flow graph for DST-I and n points signal flow graphs for DST II-IV.


Study Of Physical Layer Security And Teaching Methods In Wireless Communications, Zhijian Xie, Christopher Horne Oct 2018

Study Of Physical Layer Security And Teaching Methods In Wireless Communications, Zhijian Xie, Christopher Horne

KSU Proceedings on Cybersecurity Education, Research and Practice

In most wireless channels, the signals propagate in all directions. For the communication between Alice and Bob, an Eavesdropper can receive the signals from both Alice and Bob as far as the Eavesdropper is in the range determined by the transmitting power. Through phased array antenna with beam tracking circuits or cooperative iteration, the signals are confined near the straight line connecting the positions of Alice and Bob, so it will largely reduce the valid placement of an Eavesdropper. Sometimes, this reduction can be prohibitive for Eavesdropper to wiretap the channel since the reduced space can be readily protected. Two …


Indirect Imaging Using Computational Imaging Techniques, Aparna Viswanath Oct 2018

Indirect Imaging Using Computational Imaging Techniques, Aparna Viswanath

Electrical Engineering Theses and Dissertations

The work describes various methods employed towards solving the problem of indirect imaging. Computational techniques are employed to indirectly decipher information about an object hidden from view of a camera. Notion of virtualizing the source of illumination and detectors on real world rough surfaces was exploited to construct a non line of sight computational imager. Diversity was explored from the stand point of both illumination of the object and imaging of light reflected from the object. To understand the impact of scattering by real world rough surfaces, an instrument was developed that allows characterization of isoplanatic angle for different surface …


Implementation Of Secure Dnp3 Architecture Of Scada System For Smart Grids, Uday Bhaskar Boyanapalli Oct 2018

Implementation Of Secure Dnp3 Architecture Of Scada System For Smart Grids, Uday Bhaskar Boyanapalli

Master of Science in Computer Science Theses

With the recent advances in the power grid system connecting to the internet, data sharing, and networking enables space for hackers to maliciously attack them based on their vulnerabilities. Vital stations in the smart grid are the generation, transmission, distribution, and customer substations are connected and controlled remotely by the network. Every substation is controlled by a Supervisory Control and Data Acquisition (SCADA) system which communicates on DNP3 protocol on Internet/IP which has many security vulnerabilities. This research will focus on Distributed Network Protocol (DNP3) communication which is used in the smart grid to communicate between the controller devices. We …


No2- And No3- Enhance Cold Atmospheric Plasma Induced Cancer Cell Death By Generation Of Onoo-, Dehui Xu, Qingjie Cui, Yujing Xu, Zhijie Liu, Zeyu Chen, Wenjie Xia, Hao Zhang, Dingxin Liu, Hailan Chen, Michael G. Kong Oct 2018

No2- And No3- Enhance Cold Atmospheric Plasma Induced Cancer Cell Death By Generation Of Onoo-, Dehui Xu, Qingjie Cui, Yujing Xu, Zhijie Liu, Zeyu Chen, Wenjie Xia, Hao Zhang, Dingxin Liu, Hailan Chen, Michael G. Kong

Bioelectrics Publications

Cold atmospheric plasma (CAP) is a rapidly developed technology that has been widely applied in biomedicine especially in cancer treatment. Due to the generation of various active species in plasma, CAP could induce various tumor cells death and showed a promising potential in cancer therapy. To enhance the biological effects of gas plasma, changing the discharging parameters is the most commonly used method, yet increasing discharging power will lead to a higher possibility of simultaneously damage surrounding tissues. In this study, by adding nontoxic concentration of additional nitrite and nitrate in the medium, we found that anti-tumor effect of CAP …


Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren Oct 2018

Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren

Mechanical & Aerospace Engineering Faculty Publications

Modeling works which simulate the proton-exchange membrane fuel cell with the computational fluid dynamics approach involve the simultaneous solution of multiple, interconnected physics equations for fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts vary by how they treat the physics within and adjacent to the membrane-electrode assembly (MEA). Certain approaches treat the MEA not as part of the computational domain, but rather an interface connecting the anode and cathode computational domains. These approaches may lack the ability to consistently model catalyst layer losses and MEA ohmic resistance. This work presents an upgraded interface formulation …


Electrostatic Design And Conditioning Of A Triple Point Junction Shield For A −200 Kv Dc High Voltage Photogun, G. Palacios-Serrano, F. Hannon, C. Hernandez-Garcia, M. Poelker, H. Baumgart Oct 2018

Electrostatic Design And Conditioning Of A Triple Point Junction Shield For A −200 Kv Dc High Voltage Photogun, G. Palacios-Serrano, F. Hannon, C. Hernandez-Garcia, M. Poelker, H. Baumgart

Electrical & Computer Engineering Faculty Publications

Nuclear physics experiments performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at the Jefferson Lab require a DC high voltage photogun to generate polarized electron beams from GaAs photocathodes. The photogun uses a tapered ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. Increasing the operating voltage from nominal −130 kV to −200 kV will provide lower beam emittance, better transmission through injector apertures, and improved photocathode lifetime. This desire to increase the photogun operating voltage led to the design of a triple-point-junction shield electrode which minimizes the electric field at the delicate insulator-metal-vacuum …


Wireless Sensor Networks For Smart Communications, Mu Zhou, Qilian Liang, Hongyi Wu, Weixiao Meng, Kunjie Xu Oct 2018

Wireless Sensor Networks For Smart Communications, Mu Zhou, Qilian Liang, Hongyi Wu, Weixiao Meng, Kunjie Xu

Electrical & Computer Engineering Faculty Publications

(First paragraph) In the first edition of the special issue titled “Wireless Sensor Networks for Smart Communications”, a total of 22 manuscripts were received and 6 of these were accepted. This issue demonstrated that network congestion, user mobility, and adjacent spectrum interference are the main reasons for the degradation ofcommunication quality inWireless Sensor Networks (WSNs).


Tailoring The Asymmetric Magnetoimpedance Response In Exchange-Biased Ni - Fe Multilayers, Ufuk Kilic, Carolina Ross, Carlos Garcia Sep 2018

Tailoring The Asymmetric Magnetoimpedance Response In Exchange-Biased Ni - Fe Multilayers, Ufuk Kilic, Carolina Ross, Carlos Garcia

Ufuk Kilic

The dependence of the asymmetric magnetoimpedance (MI) response on the directions of both the magnetic field and the exchange bias is studied for an [NiFe(60nm)/IrMn(35nm)]×5 multilayer system. The antiferromagnetic (AFM) layers create an exchange bias that shifts both the hysteresis loop and the MI response of NiFe; the strength of this coupling depends on the thicknesses of both the ferromagnetic layer and the AFM layer. Tuning the exchange-bias angle and the applied-magnetic-field direction provides a practical method to control the symmetry and the magnitude of the MI response. The observed asymmetric response can …


A Nonlinear Systems Framework For Cyberattack Prevention For Chemical Process Control Systems, Helen Durand Sep 2018

A Nonlinear Systems Framework For Cyberattack Prevention For Chemical Process Control Systems, Helen Durand

Chemical Engineering and Materials Science Faculty Research Publications

Recent cyberattacks against industrial control systems highlight the criticality of preventing future attacks from disrupting plants economically or, more critically, from impacting plant safety. This work develops a nonlinear systems framework for understanding cyberattack-resilience of process and control designs and indicates through an analysis of three control designs how control laws can be inspected for this property. A chemical process example illustrates that control approaches intended for cyberattack prevention which seem intuitive are not cyberattack-resilient unless they meet the requirements of a nonlinear systems description of this property.


2018 Fall Engr333 Project Assignment, Matthew K. Heun Sep 2018

2018 Fall Engr333 Project Assignment, Matthew K. Heun

ENGR 333

The Fall 2018 ENGR333 project focused on renewable energy generation.

I asked the students “What is the largest possible reduction in Calvin’s annual energy costs from a $5M investment in renewable energy?”

Customer

The customer for this project was Russell Bray, Director of Calvin’s Physical Plant.


Androparse - An Android Feature Extraction Framework & Dataset, Robert Schmicker, Frank Breitinger, Ibrahim Baggili Sep 2018

Androparse - An Android Feature Extraction Framework & Dataset, Robert Schmicker, Frank Breitinger, Ibrahim Baggili

Electrical & Computer Engineering and Computer Science Faculty Publications

Android malware has become a major challenge. As a consequence, practitioners and researchers spend a significant time analyzing Android applications (APK). A common procedure (especially for data scientists) is to extract features such as permissions, APIs or strings which can then be analyzed. Current state of the art tools have three major issues: (1) a single tool cannot extract all the significant features used by scientists and practitioners (2) Current tools are not designed to be extensible and (3) Existing parsers do not have runtime efficiency. Therefore, this work presents AndroParse which is an open-source Android parser written in Golang …


I Know What You Did Last Summer: Your Smart Home Internet Of Things And Your Iphone Forensically Ratting You Out, Gokila Dorai, Shiva Houshmand, Ibrahim Baggili Aug 2018

I Know What You Did Last Summer: Your Smart Home Internet Of Things And Your Iphone Forensically Ratting You Out, Gokila Dorai, Shiva Houshmand, Ibrahim Baggili

Electrical & Computer Engineering and Computer Science Faculty Publications

The adoption of smart home Internet of Things (IoT) devices continues to grow. What if your devices can snitch on you and let us know where you are at any given point in time? In this work we examined the forensic artifacts produced by Nest devices, and in specific, we examined the logical backup structure of an iPhone used to control a Nest thermostat, Nest Indoor Camera and a Nest Outdoor Camera. We also integrated the Google Home Mini as another method of controlling the studied Smart Home devices. Our work is the primary account for the examination of Nest …


Digital Forensics In The Next Five Years, Laoise Luciano, Ibrahim Baggili, Mateusz Topor, Peter Casey, Frank Breitinger Aug 2018

Digital Forensics In The Next Five Years, Laoise Luciano, Ibrahim Baggili, Mateusz Topor, Peter Casey, Frank Breitinger

Electrical & Computer Engineering and Computer Science Faculty Publications

Cyber forensics has encountered major obstacles over the last decade and is at a crossroads. This paper presents data that was obtained during the National Workshop on Redefining Cyber Forensics (NWRCF) on May 23-24, 2017 supported by the National Science Foundation and organized by the University of New Haven. Qualitative and quantitative data were analyzed from twenty-four cyber forensics expert panel members. This work identified important themes that need to be addressed by the community, focusing on (1) where the domain currently is; (2) where it needs to go and; (3) steps needed to improve it. Furthermore, based on the …


Complex Coordination Silver Electrocrystallization Mechanism On Glassy Carbon Electrode Surface, Shuai-Shuai Huang, Cheng Liu, Lei Jin, Fang-Zu Yang, Zhong-Qun Tian, Shao-Min. Zhou Aug 2018

Complex Coordination Silver Electrocrystallization Mechanism On Glassy Carbon Electrode Surface, Shuai-Shuai Huang, Cheng Liu, Lei Jin, Fang-Zu Yang, Zhong-Qun Tian, Shao-Min. Zhou

Journal of Electrochemistry

Cyclic voltammetry and potential step methods were successfully used to study the electrochemical crystallization mechanism of silver deposition on glassy carbon electrode (GCE) in the practical cyanide-free silver plating electrolyte containing composite complexing agents. Scharifker-Hill (SH) theory was used to fitting the experimental data. The results showed that the electrodeposition of silver is a diffusion controlled irreversible electrode process according to three-dimensional instantaneous nucleation mechanism. When the step potential shifted from -750 mV to -825 mV, the peak deposition current Im was increased, while the induced nucleation time tm shortened. The calculated kinetic parameters showed that the diffusion coefficient (D) …


Electrochemical Performances Of Neodymium Doped Lead Dioxide Composite Anode, Hong-Hui Wang, Ming-Jie Ma, Jie Feng, Huang-Ya Kang, Wen-Jie Huang Aug 2018

Electrochemical Performances Of Neodymium Doped Lead Dioxide Composite Anode, Hong-Hui Wang, Ming-Jie Ma, Jie Feng, Huang-Ya Kang, Wen-Jie Huang

Journal of Electrochemistry

Neodymium (Nd) doped titanium (Ti)-based lead dioxide (PbO2) composite anode was prepared by electrodeposition. The surface morphologies and crystal structures of the as-prepared anodes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique, respectively. The electrochemical performances of PbO2-Nd anode were studied by electrochemical impedance spectroscopy, linear sweep voltammetry and cyclic voltammetry. Additionally, the electrocatalytic activity and durability of PbO2-Nd anode were investigated through the degradation of simulative refractory organic wastewater of phenol. The results showed that Nd doping made the PbO2 anode surface structure dense and uniform with smaller …


Assemblies And Properties Of Asymmetric Supercapacitors Based On Wo3/Carbon Cloth, Wen-Ke Shao, Lei Zhao, Chao Liu, Yan-Ying Dong, Yuan-Jie Zhu, Qiu-Fan Wang Aug 2018

Assemblies And Properties Of Asymmetric Supercapacitors Based On Wo3/Carbon Cloth, Wen-Ke Shao, Lei Zhao, Chao Liu, Yan-Ying Dong, Yuan-Jie Zhu, Qiu-Fan Wang

Journal of Electrochemistry

The demand for a new generation of flexible, portable, and high-capacity power sources increases rapidly with the development of advanced wearable electronic devices. One dimensional (1D) nanowires structures have been demonstrated as one of the most ideal electrode materials in energy storage systems due to their advantages in both micorstructures and their high surface areas. Here we report a simple process for large-scale fabrication of self-standing composite film electrodes composed of WO3 nanorods on carbon cloth. In order to improve the energy density of supercapacitor, we assembled an asymmetric supercapacitor using WO3 nanorods and activated carbon cloth as …


An Aqueous All-Metal Oxide Asymmetric Supercapacitor With High Gravimetric And Volumetric Energy Densities, Jing Xin, Xu Zhang, Wang Wei, Lang Jun-Wei Aug 2018

An Aqueous All-Metal Oxide Asymmetric Supercapacitor With High Gravimetric And Volumetric Energy Densities, Jing Xin, Xu Zhang, Wang Wei, Lang Jun-Wei

Journal of Electrochemistry

Only with both high gravimetric and high volumetric energy densities, can supercapacitors find more extensive applications.In this paper, by making good use of the interesting nanostructures and the high packing densities of RuO2 (nanoshpheres,1.69 g·cm-3) and Co-Ni oxide (nanoflakes, 2.14 g·cm-3), the RuO2//KOH//Co-Ni oxide all-metal oxide asymmetric supercapacitors with high performance were successfully fabricated, which led to the maximum specific capacitance of 217.5 F·g-1 (412.3 F·cm-3) and specific energy density of 61.8 Wh·kg-1 (121 Wh·L-1) in a cell voltage between 0 and 1.5 V in KOH electrolyte. …


Electrochemical Preparation And Photo-Electro Catalytic Properties Of Flexible Znni/Al-Ldhs/Carbon Fibers Composite, Jing-Jing Tian, Tao Chen, Xing-Chen Bao, Meng-Xu Gao, Ye-Xiao Yu, Si-Yao Peng, Guan-Ping Jin Aug 2018

Electrochemical Preparation And Photo-Electro Catalytic Properties Of Flexible Znni/Al-Ldhs/Carbon Fibers Composite, Jing-Jing Tian, Tao Chen, Xing-Chen Bao, Meng-Xu Gao, Ye-Xiao Yu, Si-Yao Peng, Guan-Ping Jin

Journal of Electrochemistry

In this work, a promising flexible composite consisting of zinc (Zn), nickel (Ni) and aluminum (Al) layered double hydroxide coated carbon fibers (ZnNi/Al-LDHs/CFs) was prepared by electrochemical method with convenient recovery and separation. The structures, morphologies, and photo-electro catalytic properties of ZnNi/Al-LDHs/CFs were characterized by X-ray diffraction, infrared spectroscopy, field emission scanning electron microscopy, inductively coupled plasma atomic emission spectrometry and electrochemical impedance spectroscopy techniques. The excellent photo-electro bifunctional catalytic properties were obtained with the ZnNi/Al-LDHs/CFs composite as compared to that of Zn/Al-LDHs/CFs (photo catalyst) or Ni/Al-LDHs/CFs (electrocatalyst) alone, which could be used in the electro-catalytic oxidations of methanol and …


Preparation And Characterization Of Self-Supporting Flexible Nitrogen-Doped Carbon Fabric Electrodes, Bo Yang, Zhi-Hang Jin, Ya-Ping Zhao, Zai-Sheng Cai Aug 2018

Preparation And Characterization Of Self-Supporting Flexible Nitrogen-Doped Carbon Fabric Electrodes, Bo Yang, Zhi-Hang Jin, Ya-Ping Zhao, Zai-Sheng Cai

Journal of Electrochemistry

With the wide applications of intelligent wearable devices in various fields, developing a new generation of flexible energy storage devices has become a major challenge for the current technology. As a wide application of wearable flexible substrate, cotton fabric has the advantages over low price, non-toxic and environmental friendly, but the poor conductivity becomes a major problem limiting its development. As a nitrogen-containing conducting polymer, polypyrrole is traditionally used as electrode materials, but poor mechanical performance and cycle stability severely limit its application in electrode materials. In this article, a self-supporting flexible nitrogen-doped carbon fabric electrode was prepared by in …


Hybrid Battery-Capacitor System Based On Liti5O12 Anode And Ptpan Cathode, Xiu-Li Su, Xiao-Li Dong, Yao Liu, Yong-Gang Wang, Ai-Shui Yu Aug 2018

Hybrid Battery-Capacitor System Based On Liti5O12 Anode And Ptpan Cathode, Xiu-Li Su, Xiao-Li Dong, Yao Liu, Yong-Gang Wang, Ai-Shui Yu

Journal of Electrochemistry

Owing to its high safe, high rate and long life characteristics, lithium titanate (Li4Ti5O12) anode material has attracted extensive attention in recent years, and many efforts are being made to develop the Li4Ti5O12 based high performance hybrid supercapacitors and Li-ion batteries. Herein, we prepared the organic cathode material polytriphenylamine (PTPAn) through chemical oxidation and polymerization of triphenylamine (TPAn), and investigated its charge storage mechanism and electrode kinetics withthe typical electrochemical methods in an organic electrolyte. It was demonstrated that the PTPAn exhibited the reversible capacity of 85 mA·g-1 …


Highly Crystalline Nickel Borate Nanorods As Oxygen Evolution Reaction Electrocatalysts, Xi Xu, Juan Liu, Hua-Zong Wu, Wen-Jie Jiang Aug 2018

Highly Crystalline Nickel Borate Nanorods As Oxygen Evolution Reaction Electrocatalysts, Xi Xu, Juan Liu, Hua-Zong Wu, Wen-Jie Jiang

Journal of Electrochemistry

Hydrogen energy, a kind of clean and renewable energy, is considered to be the solution to the problems of energy crisis and environmental deterioration. Electrochemical water splitting is an efficient and promising technology for the production of high-purity hydrogen. However, oxygen evolution reaction (OER) at the anode of water electrolyzer limits the efficiency of water splitting due to the high overpotential. Therefore, the challenges still remain for the exploration of highly active, stable and low-cost catalysts with superior activity for OER. Herein, nickel borate nanorods with high crystallinity were prepared via high-temperature calcination. The as-obtained nickel borate nanorods with 2 …


Chaos Firefly Algorithm With Self-Adaptation Mutation Mechanism For Solving Large-Scale Economic Dispatch With Valve-Point Effects And Multiple Fuel Options, Yude Yang, Bori Wei, Hui Liu, Yiyi Zhang, Junhui Zhao, Emad Manla Aug 2018

Chaos Firefly Algorithm With Self-Adaptation Mutation Mechanism For Solving Large-Scale Economic Dispatch With Valve-Point Effects And Multiple Fuel Options, Yude Yang, Bori Wei, Hui Liu, Yiyi Zhang, Junhui Zhao, Emad Manla

Electrical & Computer Engineering and Computer Science Faculty Publications

This paper presents a new metaheuristic optimization algorithm, the firefly algorithm (FA), and an enhanced version of it, called chaos mutation FA (CMFA), for solving power economic dispatch problems while considering various power constraints, such as valve-point effects, ramp rate limits, prohibited operating zones, and multiple generator fuel options. The algorithm is enhanced by adding a new mutation strategy using self-adaptation parameter selection while replacing the parameters with fixed values. The proposed algorithm is also enhanced by a self-adaptation mechanism that avoids challenges associated with tuning the algorithm parameters directed against characteristics of the optimization problem to be solved. The …


Robust Engineering Of Dynamic Structures In Complex Networks, Walter Botongo Bomela Aug 2018

Robust Engineering Of Dynamic Structures In Complex Networks, Walter Botongo Bomela

McKelvey School of Engineering Theses & Dissertations

Populations of nearly identical dynamical systems are ubiquitous in natural and engineered systems, in which each unit plays a crucial role in determining the functioning of the ensemble. Robust and optimal control of such large collections of dynamical units remains a grand challenge, especially, when these units interact and form a complex network. Motivated by compelling practical problems in power systems, neural engineering and quantum control, where individual units often have to work in tandem to achieve a desired dynamic behavior, e.g., maintaining synchronization of generators in a power grid or conveying information in a neuronal network; in this dissertation, …


Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott Aug 2018

Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott

Arts & Sciences Electronic Theses and Dissertations

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) using the higher polarization of electron radical spins compared to nuclear spins. The addition of electron radicals for DNP to the sample can cause hyperfine broadening, which decreases the resolution of the NMR resonances due to hyperfine interactions between electron and nuclear spins. Electron decoupling has been shown to attenuate the effects of hyperfine coupling in rotating solids. Magic angle spinning (MAS) DNP with electron decoupling requires a high electron Rabi frequency provided by a high-power microwave source such as a frequency-agile gyrotron. This dissertation describes the development …


Self-Powered Time-Keeping And Time-Of-Occurrence Sensing, Liang Zhou Aug 2018

Self-Powered Time-Keeping And Time-Of-Occurrence Sensing, Liang Zhou

McKelvey School of Engineering Theses & Dissertations

Self-powered and passive Internet-of-Things (IoT) devices (e.g. RFID tags, financial assets, wireless sensors and surface-mount devices) have been widely deployed in our everyday and industrial applications. While diverse functionalities have been implemented in passive systems, the lack of a reference clock limits the design space of such devices used for applications such as time-stamping sensing, recording and dynamic authentication. Self-powered time-keeping in passive systems has been challenging because they do not have access to continuous power sources. While energy transducers can harvest power from ambient environment, the intermittent power cannot support continuous operation for reference clocks. The thesis of this …


The Hilbert-Huang Transform: A Theoretical Framework And Applications To Leak Identification In Pressurized Space Modules, Kenneth R. Bundy Aug 2018

The Hilbert-Huang Transform: A Theoretical Framework And Applications To Leak Identification In Pressurized Space Modules, Kenneth R. Bundy

Electronic Theses and Dissertations

Any manned space mission must provide breathable air to its crew. For this reason, air leaks in spacecraft pose a danger to the mission and any astronauts on board. The purpose of this work is twofold: the first is to address the issue of air pressure loss from leaks in spacecraft. Air leaks present a danger to spacecraft crew, and so a method of finding air leaks when they occur is needed. Most leak detection systems localize the leak in some way. Instead, we address the identification of air leaks in a pressurized space module, we aim to determine the …