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Articles 1 - 30 of 7510
Full-Text Articles in Engineering
Implications Of Electric Vehicles On Gasoline Tax Revenues, Florida Solar Energy Center, Kevin Schleith
Implications Of Electric Vehicles On Gasoline Tax Revenues, Florida Solar Energy Center, Kevin Schleith
FSEC Energy Research Center®
This report summarizes the results of research conducted to determine if current and near future EV sales will have an impact on gasoline (gas) tax revenues as part of the Federal Highway Trust Fund (HTF). Gasoline taxes account for $31.1 billion or about 87% of the HTF. The project results were accomplished through a review of existing industry and government reports that detail fuel tax revenues and through analysis of EV sales from 2010 to 2015.
14-08 Big Data Analytics To Aid Developing Livable Communities, Li Yang, Hyunkeun Cho, Jun-Seok Oh
14-08 Big Data Analytics To Aid Developing Livable Communities, Li Yang, Hyunkeun Cho, Jun-Seok Oh
Transportation Research Center Reports
In transportation, ubiquitous deployment of low-cost sensors combined with powerful computer hardware and high-speed network makes big data available. USDOT defines big data research in transportation as a number of advanced techniques applied to the capture, management and analysis of very large and diverse volumes of data. Data in transportation are usually well organized into tables and are characterized by relatively low dimensionality and yet huge numbers of records. Therefore, big data research in transportation has unique challenges on how to effectively process huge amounts of data records and data streams. The purpose of this study is to conduct research …
Atap Otomatis Sensor Suhu, Air Dan Tenaga Surya (Alas Tsusu), Koko Hendriawan
Atap Otomatis Sensor Suhu, Air Dan Tenaga Surya (Alas Tsusu), Koko Hendriawan
Elinvo (Electronics, Informatics, and Vocational Education)
Atap otomatis sensor suhu,sensor air dan surya(ALAS TSUSU) sebagai inovasi desain atap yang dapat membuka dan menutup secara otomatis.Atap adalah salah satu komponen yang sangat penting dalam sebuah bangunan. Dengan adanya dua musim yang di miliki Negara Indonesia Antara musim hujan dan kemarau atap tidak hanya sebagai fungsi utama dalam melidungi kita dari matahari dan hujan akan tetapi juga memiliki nilai estetika yang sangat tinggi misalnya intensitas cahaya yang diterima bumi kurang terang dengan rain probability (kemungkinan turun hujan) tinggi. Sedangkan pada musim kemarau, sinar matahari lebih terang dengan kemungkinan turun hujan sangat rendah, bahkan hampir tidak pernah turun hujan. …
Analisis Penerapan Sistem Informasi Akademik (Siakad) 2013 Menggunakan Model End-User Computing Satisfaction (Eucs) Di Program Studi Pendidikan Teknik Informatika, Handaru Jati
Elinvo (Electronics, Informatics, and Vocational Education)
Penelitian ini bertujuan untuk mengetahui: (1) pengaruh content terhadap user satisfaction; (2) pengaruh accuracy terhadap user satisfaction; (3) pengaruh format terhadap user satisfaction; (4) pengaruh ease of use terhadap user satisfaction; (5) pengaruh timeliness terhadap user satisfaction. Penelitian ini merupakan penelitian ex-post facto, yang dilaksanakan di Program Studi Pendidikan Teknik Informatika. Teknik pengambilan sampel dengan purposive sampling. Sampel yang diambil merupakan mahasiswa angkatan 2013 dan 2014 yang sudah menggunakan SIAKAD 2013 . Data diperoleh dengan kuesioner tertutup yang telah memenuhi persyaratan validitas dan reliabilitas. Teknik analisis data yang digunakan adalah Partial Least Square (PLS). Hasil penelitian menunjukkan bahwa: (1) content …
Penilaian Efisiensi Universitas Lptk Di Indonesia Dengan Menggunakan Data Envelopment Analysis, Handaru Jati
Penilaian Efisiensi Universitas Lptk Di Indonesia Dengan Menggunakan Data Envelopment Analysis, Handaru Jati
Elinvo (Electronics, Informatics, and Vocational Education)
Seiring meningkatnya keinginan untuk melanjutkan kuliah ke Perguruan Tinggi bagi lulusan sekolah menengah di Indonesia dan semakin tingginya biaya yang ditanggung oleh calon mahasiswa, pemerintah dihadapkan pada kondisi untuk mendorong universitas agar dapat beroperasi dengan lebih efisien dan lebih produktif. Tujuan penelitian ini adalah mengembangkan metode baru penilaian efisiensi universitas Lembaga Pendidikan Tenaga Keguruan (LPTK) di Indonesia dengan mempergunakan Data Envelopment Analysis yang secara teknis efektif untuk menghitung efisiensi sebuah Universitas. Penelitian ini merupakan penelitian research and development yang dilaksanakan dalam kegiatan yang meliputi analisis kebutuhan yaitu pengkajian variabel yang akan menjadi factor penilaian efisiensi beserta mekanisme pengumpulan datanya, disain …
Analysis Of Productivity In Dredging Project : A Case Study In Port Of Tanjung Perak Surabaya – Indonesia, Tiggi P. Hardya
Analysis Of Productivity In Dredging Project : A Case Study In Port Of Tanjung Perak Surabaya – Indonesia, Tiggi P. Hardya
World Maritime University Dissertations
No abstract provided.
How Can We Build A Moral Robot?, Kristen E. Clark
How Can We Build A Moral Robot?, Kristen E. Clark
Capstones
Artificial intelligence is already starting to drive our cars and make choices that affect the world economy. One day soon, we’ll have robots that can take care of our sick and elderly, and even rescue us in rescue us in emergencies. But as robots start to make decisions that matter—it’s raising questions that go far beyond engineering. We’re stating to think about ethics.
Bertram Malle and Matthias Scheutz are part of a team funded by the department of defense. It's their job to answer a question that seems straight out of a sci-fi novel: How can we build a moral …
Influence Of The Substrate Characteristics On The Bond Behavior Of Pbo Frcm-Concrete Joints, Tommaso D'Antino, Lesley H. Sneed, Christian Carloni, Carlo Pellegrino
Influence Of The Substrate Characteristics On The Bond Behavior Of Pbo Frcm-Concrete Joints, Tommaso D'Antino, Lesley H. Sneed, Christian Carloni, Carlo Pellegrino
Civil, Architectural and Environmental Engineering Faculty Research & Creative Works
Fiber Reinforced Cementitious Matrix (FRCM) composites can be employed as a valid alternative to Fiber Reinforced Polymers (FRP) composites for strengthening existing reinforced concrete (RC) structures. The weakness of FRCM-concrete joints has been reported to be at the matrix-fiber interface rather than within the concrete substrate, as is usually reported in the case of FRP-concrete joints. The experimental investigations regarding FRCM strengthening available in the literature have been performed by applying the FRCM composite onto a surface that was treated before the application, usually by grinding or sandblasting. However, the role of the substrate characteristics on the failure mechanism of …
Special Issue: Electrochemistry Of Carbon Materials, Wei Chen
Special Issue: Electrochemistry Of Carbon Materials, Wei Chen
Journal of Electrochemistry
Carbon materials are traditional electrode materials due to their excellent electrical conductivities, high electrochemical stabilities and wide potential windows. Glassy carbon, graphite, various activated charcoals, carbon fibers etc. have been widely used in electrochemistry serving as electrode substrates or supports. In addition to their applications in basic electrochemistry, carbon materials have also played important roles in electrochemical energy storage and conversion. In recent years, various types of carbon structures, from zero-dimensional carbon nanodots, one-dimensional nanotubes, two-dimensional graphene to three-dimensional porous carbons, have attracted increasing attention in electrochemical field. It has been found that carbon materials have outstanding properties as advanced …
Applications Of Carbon Materials In Electrochemical Energy Storage, Ji Liang, Lei Wen, Hui-Ming Cheng, Feng Li
Applications Of Carbon Materials In Electrochemical Energy Storage, Ji Liang, Lei Wen, Hui-Ming Cheng, Feng Li
Journal of Electrochemistry
An electrode material for electrochemical energy storage is one of the key components for high performance devices. In a variety of electrochemical energy storage systems, carbon materials, especially the lately emerged carbon nanomaterials including the carbon nanotube and graphene, have been playing a very important role and brought new vitality to the development and demonstration of the broad application prospects. In this review, we summarize the applications of various carbon materials in the typical electrochemical energy storage devices, namely lithium/sodium ion batteries, supercapacitors, and lithium-sulfur batteries, as well as flexible electrochemical energy storage and electrochemical catalysis. A perspective of novel …
Progress Of Self-Supported Supercapacitor Electrode Materials Based On Carbon Substrates, Shui-Jian He, Wei Chen
Progress Of Self-Supported Supercapacitor Electrode Materials Based On Carbon Substrates, Shui-Jian He, Wei Chen
Journal of Electrochemistry
Self-supported electrode materials have been widely used in supercapacitors. Carbon materials are promising substrates in building self-supported electrode materials attributed to their diverse structures, rich resource, relatively low cost and high stability. Combined with our own research in this field, we summarize here the recent progress on the synthesis of self-supported electrode materials and their supercapacitance properties. The overall synthetic strategy could be divided into two categories: “top-down” and “bottom-up”. We hope this review is helpful for the development and application of renewable sources in self-supported electrode materials.
Carbon Aerogel/Nickel Foam As Electrode For High-Performance Supercapacitor, Zhong Wu, Xin-Bo Zhang
Carbon Aerogel/Nickel Foam As Electrode For High-Performance Supercapacitor, Zhong Wu, Xin-Bo Zhang
Journal of Electrochemistry
Herein, a facile synthesis has been explored to prepare carbon aerogel/Ni foam. Graphene oxide, resorcinol and formaldehyde serve as precursors and polymerize in-situ on the Ni foam after hydrothermal synthesis at 85 ℃. After lyophilization treatment, the carbon aerogel/Ni foam with porous structure can be obtained. Electrochemical investigations reveal that the carbon aerogel/Ni foam exhibits superior performances in both aqueous and organic electrolytes involving high specific capacitance and long-term cycling stability. The excellent properties can be ascribed to the unique formation and porous structure, which allows more effective transportations of electron and electrolyte ion.
Fast And Accurate Evaluation Of Lifepo4 Cathode Materials By Single Particle Microelectrode, Fu-Qing Wang, Yi-Min Wei, Yu-Zhuan Su, Bing-Wei Mao, Kai Wu, Feng-Gang Zhao, Chun-Lei Chen, Xing-Lu Li, Jin Chong
Fast And Accurate Evaluation Of Lifepo4 Cathode Materials By Single Particle Microelectrode, Fu-Qing Wang, Yi-Min Wei, Yu-Zhuan Su, Bing-Wei Mao, Kai Wu, Feng-Gang Zhao, Chun-Lei Chen, Xing-Lu Li, Jin Chong
Journal of Electrochemistry
Single particle microelectrode enables to evaluate the electrochemical responses for single particle of active material without binder and conductive agent. Thus, the influences of additive and electrode structure on the electrochemical performance of active materials can be ignored. Furthermore, this technology can be used to evaluate active materials fast. Therefore, single particle microelectrode allows fast and accurate determination of the intrinsic performance of active material. Cyclic voltammogram (CV), cycle performance, and kinetic behavior of LiFePO4 cathode materials were evaluated by the single particle microelectrode. CV curve of LiFePO4 particle with a pair of oxidation and reduction peaks was …
Electrochemical Properties Of Graphene/Porous Nano-Silicon Anode, Chun-Li Li, Guang Yang, Ping Zhang, Zhi-Yu Jiang
Electrochemical Properties Of Graphene/Porous Nano-Silicon Anode, Chun-Li Li, Guang Yang, Ping Zhang, Zhi-Yu Jiang
Journal of Electrochemistry
Porous nano-silicon (Si) was prepared by acid etching Al-Si alloy powder method, and used as an active material for fabricating a grapene/porous nano-Si electrode. The results of SEM and TEM measurements indicated that porous nano-Si powder was uniformly mixed with graphene by emulsification dispersion-ultrasonication method. As an anode for lithium ion battery, the graphene/porous nano-Si electrode presented relatively high performance in 1 mol•L-1LiPF6/EC:DMC = 1:1(by volume) + 1.5% (by mass) VC solution. At the charge and discharge current densities of 0.5A•g-1, the first discharge capacity was 1768.6mAh•g-1with coulombic efficiency of 68.3%. The discharge capacity …
Colloidal Ionic Supercapacitors, Kun-Feng Chen, Dong-Feng Xue
Colloidal Ionic Supercapacitors, Kun-Feng Chen, Dong-Feng Xue
Journal of Electrochemistry
Supercapacitors have high power density and long cycle life compared with battery systems, but they still suffer from low energy density at the same time. In order to increase the energy density of supercapacitors, we have developed a new type of pseudocapacitor, called colloidal ion supercapacitor, which can directly use commercial metal salts as electrode materials and form electroactive matter by in-situ electrochemical reactions without the need of additional materials synthesis processes. Colloidal ion supercapacitor can fully utilize the redox reaction of metal cations with multiple oxidation states, which can completely release the stored electrical energy of multiple-valence cations, leading …
Electrodeposition Of Lanthanum In Deep Eutectic Solvents, Li Wang, You-Jun Fan, Lu Wei, Hai-Xia Liu, Shi-Gang Sun
Electrodeposition Of Lanthanum In Deep Eutectic Solvents, Li Wang, You-Jun Fan, Lu Wei, Hai-Xia Liu, Shi-Gang Sun
Journal of Electrochemistry
With the choline chloride/urea deep eutectic solvents (DESs) as the medium, the olive-like lanthanum particles with uniform shape and size were successfully prepared through a potentiostatic deposition method. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). At the same time, the effect of deposition potential, temperature and time on the size and morphology of samples was investigated. The results demonstrated that the optimum conditions for the preparation of olive-like lanthanum particles were as follows: deposition potential of -1.7 V, temperature of 80 °C and …
Synthesis Of Porous Carbon Nanosheets And Its Application In Sodium-Ion Battery, Jing-Fei Zhang, Jing Lu, Xiao-Yu Yang, Yun-Di Huang, Lin Xu, Dong-Mei Sun, Ya-Wen Tang
Synthesis Of Porous Carbon Nanosheets And Its Application In Sodium-Ion Battery, Jing-Fei Zhang, Jing Lu, Xiao-Yu Yang, Yun-Di Huang, Lin Xu, Dong-Mei Sun, Ya-Wen Tang
Journal of Electrochemistry
Owning to sodium’s high abundance, relatively low cost, similar chemical properties to Li and very suitable redox potential of E0(Na+/Na) = -2.71 V versus SHE which is only 0.3 V above that of lithium, rechargeable sodium ion battery hold much promise as potential alternatives to current lithium ion batteries for energy storage applications. Carbon material is regarded as the most promising anode candidate for sodium ion battery. Particularly, carbon nanosheet with porous structure and high conductivity is expected to have improved sodium ion storage properties. In this paper, we present a two-step pyrolysis-based method for facile …
Intercalation Of Clo4- Into Hopg Investigated By Ec-Stm, Xiao-Yan Hu, Alice Aliwowe, Jia-Wei Yan, Bing-Wei Mao
Intercalation Of Clo4- Into Hopg Investigated By Ec-Stm, Xiao-Yan Hu, Alice Aliwowe, Jia-Wei Yan, Bing-Wei Mao
Journal of Electrochemistry
The electrochemical intercalation and surface morphology of highly oriented pyrolytic graphite (HOPG) electrode in 2 mol⋅L-1 HClO4 were studied by in situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV). Based on the step-height changes observed before and after the intercalation, the effects of different step sites on intercalation are compared. The feasibility, reversibility and speed of intercalation are discussed. The intercalation ofClO4- into HOPG can be divided into three types depending on the number of graphite layers at the step site: When the layers of graphite are more than three, the intercalation becomes feasible; when …
Effect Of Mno2 Content On Electrochemical Capacitance Behavior Of Active Carbon Electrode, Kun Shen, Xian-Liang Zhou, Qi-Shun Duan
Effect Of Mno2 Content On Electrochemical Capacitance Behavior Of Active Carbon Electrode, Kun Shen, Xian-Liang Zhou, Qi-Shun Duan
Journal of Electrochemistry
In this work, the manganese dioxide (MnO2) materials were prepared by solution approach at low temperature, thermal decomposition and electrochemical deposition. The actived carbon (AC) and MnO2composite electrodes were used for aqueous supercapacitors. The morphologies and structures of the prepared materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the electrochemical behaviors were tested by cyclic voltammetry (CV) and galanostatic charge-discharge tests. Electrochemical test data show that the maximum specific capacitances of 151, 172 and 141 F•g-1were obtained with the contents of MnO2being 70, 60 and 70% in …
System-Wide Prediction Of General, All-Cause, Preventable Hospital Readmissions, Ken Musselman, Brandon Pope, Steve Witz, Zhiyi Tian, Lingsong Zhang, Linda Leon, Ann Davis
System-Wide Prediction Of General, All-Cause, Preventable Hospital Readmissions, Ken Musselman, Brandon Pope, Steve Witz, Zhiyi Tian, Lingsong Zhang, Linda Leon, Ann Davis
RCHE Publications
Existing studies of hospital readmissions typically focus on specific diagnoses, age groups, discharge dispositions, payer classes, or hospitals, and often use small samples. It is not clear how predictive models generated from such studies generalize across diseases, hospitals, or time periods. In this study, a logistic regression model of readmission risk within 30 days based on hospital administrative data was constructed and validated across hospitals and time periods. The hospitals included both general and specialty hospitals such as long-term care, women’s, and children’s hospitals. The administrative data included information on patient’s demographics, diagnoses, procedures, and discharge disposition. Derivation and validation …
Collecting Unsolicited User-Generated Change Requests, Joseph W. Goldsmith
Collecting Unsolicited User-Generated Change Requests, Joseph W. Goldsmith
Theses and Dissertations
Unlike aircrew directly associated with acquisitions, line operators are not fully engaged in the methods to push materiel hardware or software change requests up the chain, to a decision maker, and then to the engineers. The Air Force trains these end users to logically apply expert systems knowledge to execute the mission but has not fully leveraged this resource for properly identifying and correcting operational shortfalls in an aircraft's design. Focusing on the Remotely Piloted Aircraft (RPA) community, the research goal is to determine if the Air Force should establish a formal program for collecting and prioritizing unsolicited user change …
Comparison Of Novel Carboneous Structures To Treat Nitroaromatic Impacted Water, Benjamin M. Doane
Comparison Of Novel Carboneous Structures To Treat Nitroaromatic Impacted Water, Benjamin M. Doane
Theses and Dissertations
Carboneous materials such as carbon nanotube (CNT), granular activated carbon (GAC), and biochar are promising materials for the removal of organic contaminants from aqueous phase solutions. CNTs have astonishing mechanical strength, chemical and thermal stability and high surface area. While biochar, similar to GAC, having an extremely porous structure and high surface area, can be produced in more austere conditions with native materials. In this study, novel CNT-Hybrid structures (CNT-HS), hardwood pellet (HWP) Biochar and standard GAC (F-600 GAC) were used as adsorbents to treat water contaminated by a model nitroaromatic compound, 2,4-dinitrotoluene (DNT).
Effects Of Automation On Aircrew Workload And Situation Awareness In Tactical Airlift Missions, David R. Meyer
Effects Of Automation On Aircrew Workload And Situation Awareness In Tactical Airlift Missions, David R. Meyer
Theses and Dissertations
In tactical aviation, decision superiority brought upon by high situation awareness remains the arbiter of combat effectiveness. The advancement of sophisticated avionics and highly automated cockpits has allowed for the reduction of aircrew size, and in certain platforms, removal of the crew from the aircraft entirely. However, these developments have not reduced the complex and dynamic interaction between situation awareness and crew workload. While many predictive and experimental methods of evaluating workload exist, situation awareness can only be measured by conducting trials with human operators in a functional prototype. This thesis proposes an innovative methodology to predicatively determine situation awareness …
Design And Implementation Of A Unified Command And Control Architecture For Multiple Cooperative Unmanned Vehicles Utilizing Commercial Off The Shelf Components, Jeremy Gray
Theses and Dissertations
Small unmanned systems provide great utility to military applications due to their portable and expendable design. These systems are, however, costly to develop, produce, and maintain, making it desirable to integrate available commercial off the shelf (COTS) components. This research investigates the integration of COTS components through the development of a modular unified command and control (C2) architecture for heterogeneous and homogeneous vehicle teams to accomplish formation flocking and communication relay scenarios. A vehicle agnostic architecture was developed to be applied across different vehicle platforms, different vehicle combination, and different cooperative missions. COTS components consisting primarily of open source hardware …
Feature Selection And Classifier Development For Radio Frequency Device Identification, Trevor J. Bihl
Feature Selection And Classifier Development For Radio Frequency Device Identification, Trevor J. Bihl
Theses and Dissertations
The proliferation of simple and low-cost devices, such as IEEE 802.15.4 ZigBee and Z-Wave, in Critical Infrastructure (CI) increases security concerns. Radio Frequency Distinct Native Attribute (RF-DNA) Fingerprinting facilitates biometric-like identification of electronic devices emissions from variances in device hardware. Developing reliable classifier models using RF-DNA fingerprints is thus important for device discrimination to enable reliable Device Classification (a one-to-many looks most like assessment) and Device ID Verification (a one-to-one looks how much like assessment). AFITs prior RF-DNA work focused on Multiple Discriminant Analysis/Maximum Likelihood (MDA/ML) and Generalized Relevance Learning Vector Quantized Improved (GRLVQI) classifiers. This work 1) introduces a …
Application Of Executable Architectures In Early Concept Evaluation, Ryan M. Pospisal
Application Of Executable Architectures In Early Concept Evaluation, Ryan M. Pospisal
Theses and Dissertations
This research explores use of executable architectures to guide design decisions in the early stages of system development. Decisions made early in the system development cycle determine a majority of the total lifecycle costs as well as establish a baseline for long term system performance and thus it is vital to program success to choose favorable design alternatives. The development of a representative architecture followed the Architecture Based Evaluation Process as it provides a logical and systematic order of events to produce an architecture sufficient to document and model operational performance. In order to demonstrate the value in the application …
Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Theses and Dissertations
Ultra high temperature ceramics (UHTCs) are leading candidates for aerospace structural applications in high temperature environments, including the leading edges of hypersonic aircraft and thermal protection systems for atmospheric re-entry vehicles. Before UHTCs can be used in such applications, their structural integrity and environmental durability must be assured, which requires a thorough understanding and characterization of their creep and oxidation behavior at relevant service temperatures.
Optimal Attitude Control Of Agile Spacecraft Using Combined Reaction Wheel And Control Moment Gyroscope Arrays, Cole C. Doupe
Optimal Attitude Control Of Agile Spacecraft Using Combined Reaction Wheel And Control Moment Gyroscope Arrays, Cole C. Doupe
Theses and Dissertations
This dissertation explores the benefits of combined control moment gyroscope (CMG) and reaction wheel array (RWA) actuation for agile spacecraft. Agile spacecraft are capable of slewing to multiple targets in minimum time. CMGs provide the largest torque capability of current momentum exchange actuation devices but also introduce singularity events in operation. RWAs produce less torque capability than CMGs but can achieve greater pointing accuracy. In this research, a combined RWA and CMG (RWCMG) system is evaluated using analytical simulations and hardware experiments. A closed-loop control scheme is developed which takes advantage of the strengths of each actuator set.The CMGs perform …
Optimal Uas Assignments And Trajectories For Persistent Surveillance And Data Collection From A Wireless Sensor Network, Nidal M. Jodeh
Optimal Uas Assignments And Trajectories For Persistent Surveillance And Data Collection From A Wireless Sensor Network, Nidal M. Jodeh
Theses and Dissertations
This research developed a method for multiple Unmanned Aircraft Systems (UAS) to efficiently collect data from a Wireless Sensor Networks (WSN). WSN are composed of any number of fixed, ground-based sensors that collect and upload local environmental data to over flying UAS. The three-step method first uniquely assigns aircraft to specific sensors on the ground. Second, an efficient flight path is calculated to minimize the aircraft flight time required to verify their assigned sensors. Finally, sensors reporting relatively higher rates of local environmental activity are re-assigned to dedicated aircraft tasked with concentrating on only those sensors. This work was sponsored …
Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 800°C In Air And In Silicic Acid-Saturated Steam, Scott J. Robertson
Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 800°C In Air And In Silicic Acid-Saturated Steam, Scott J. Robertson
Theses and Dissertations
A facility was demonstrated that successfully resolved problems highlighted by previous attempts to study SiC fibers in steam. Monotonic tension and creep tests were conducted to characterize the fibers. The tensile strength of the fibers showed little dependence on applied stress rate, indicating a resistance to environmentally assisted crack growth. Climb-controlled diffusion in air and grain boundary sliding in silicic acid-saturated steam were the dominant damage mechanisms. Silicic acid-saturated steam had a degrading effect on the mechanical performance of the fibers, but much less than unsaturated steam environments. The Monkman-Grant relationship was demonstrated for Hi-NicalonTM S fibers and may be …