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Articles 20671 - 20700 of 27464

Full-Text Articles in Engineering

Math, Science, And Engineering Integration In A High School Engineering Course: A Qualitative Study, Clara G. Valtorta, Leema K. Berland Apr 2015

Math, Science, And Engineering Integration In A High School Engineering Course: A Qualitative Study, Clara G. Valtorta, Leema K. Berland

Journal of Pre-College Engineering Education Research (J-PEER)

Engineering in K-12 classrooms has been receiving expanding emphasis in the United States. The integration of science, mathematics, and engineering is a benefit and goal of K-12 engineering; however, current empirical research on the efficacy of K-12 science, mathematics, and engineering integration is limited. This study adds to this growing field, using discourse analysis techniques to examine whether and why students integrate math and science concepts into their engineering design work. The study focuses on student work during a unit from a high school engineering course. Video data were collected during the unit and were used to identify episodes of …

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Beyond Blackboards: Engaging Underserved Middle School Students In Engineering, Sarah Blanchard, Justina Judy, Chandra Muller, Richard H. Crawford, Anthony J. Petrosino, Christina K. White, Fu-An Lin, Kristin L. Wood Apr 2015

Beyond Blackboards: Engaging Underserved Middle School Students In Engineering, Sarah Blanchard, Justina Judy, Chandra Muller, Richard H. Crawford, Anthony J. Petrosino, Christina K. White, Fu-An Lin, Kristin L. Wood

Journal of Pre-College Engineering Education Research (J-PEER)

Beyond Blackboards is an inquiry-centered, after-school program designed to enhance middle school students’ engagement with engineering through design-based experiences focused on the 21st Century Engineering Challenges. Set within a predominantly lowincome, majority-minority community, our study aims to investigate the impact of Beyond Blackboards on students’ interest in and understanding of engineering, as well as their ability to align their educational and career plans. We compare participants’ and nonparticipants’ questionnaire responses before the implementation and at the end of the program’s first academic year. Statistically significant findings indicate a school-wide increase in students’ interest in engineering careers, supporting a shift in …

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Researches On In-Situ And Ex-Situ Characterization Techniques In Lithium Batteries, Wen-Jun Li, Jie-Yun Zheng, Lin Gu, Hong Li Apr 2015

Researches On In-Situ And Ex-Situ Characterization Techniques In Lithium Batteries, Wen-Jun Li, Jie-Yun Zheng, Lin Gu, Hong Li

Journal of Electrochemistry

Electrochemical performance of Lithium batteries is directly linked to interfacial transports, reactions and storing behaviors of electrons and ions at bulk-surface interfaces. It is extremely important to conduct evolution studies from atomic level to macro level in electron structures, crystal structures, microstructures and morphologies, chemical compositions and physical properties of battery materials at equilibrium and nonequilibrium in order to understand various structure-performance relations in lithium ion batteries. Advanced in-situ and ex-situ characterization techniques have been used widely to clarify scientific and technological problems in lithium batteries. This paper summarizes our efforts on battery researches using various experimental techniques, including in …

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Recent Research Progress For Non-Pt-Based Oxygen Reduction Reaction Electrocatalysts In Fuel Cell, Ping Song, Ming-Bo Ruan, Jing Liu, Guang-Jun Ran, Wei-Lin Xu Apr 2015

Recent Research Progress For Non-Pt-Based Oxygen Reduction Reaction Electrocatalysts In Fuel Cell, Ping Song, Ming-Bo Ruan, Jing Liu, Guang-Jun Ran, Wei-Lin Xu

Journal of Electrochemistry

The expensive Pt-based catalyst suffers from its susceptibility to time-dependent drift, methanol crossover, and carbon monoxide (CO) deactivation, which will block the large-scale commercial application of fuel cells. It is, therefore, necessary to develop efficient, low-cost, highly stable non-precious metal oxygen reduction reaction (ORR) catalysts with high catalytic performance. Here, we will pay attention to the research progress of non-precious metal and heteroatom-doped (N, B, P, S, F) metal-free ORR catalysts. Importantly, we mainly focus on the work developed by Xu’s group with the Fe-based non-precious metal and F/NF-doped metal-free ORR catalysts. The purpose of these works is to improve …

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Research Progress Of Mn-Based Lithium-Rich Cathode Materials For Li-Ion Batteries, Luo-Zeng Zhou, Qun-Jie Xu, Wei-Ping Tang, Xue Jin, Xiao-Lei Yuan Apr 2015

Research Progress Of Mn-Based Lithium-Rich Cathode Materials For Li-Ion Batteries, Luo-Zeng Zhou, Qun-Jie Xu, Wei-Ping Tang, Xue Jin, Xiao-Lei Yuan

Journal of Electrochemistry

With rapid development of new energy industry like electric vehicles and energy storage station, these fields highly demand the next generation of high performance Li-ion battery systems with stronger energy density, higher power density, and longer cycling life. Lithium-rich Mn-based cathode materials, xLi2MnO3·(1-x)LiMO2(M=Mn, Co, Ni...), have become the hot topic and drawn attentions of scholars worldwide because of their high reversible capacity exceeding 240 mAh·g-1, excellent electrochemical properties, and low cost, which makes them most promising cathode material candidates for next Li-ion battery system. The cathode material Li[Li0.2Mn0.54Ni …

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Preparation And Properties Of Binary Oxides CoXCr1-XO3/2 Electrocatalysts For Oxygen Evolution Reaction, Tai-Lai Yang, Wen-Yan Dong, Hui-Min Yang, Li Zhang, Zhen-Hai Liang Apr 2015

Preparation And Properties Of Binary Oxides CoXCr1-XO3/2 Electrocatalysts For Oxygen Evolution Reaction, Tai-Lai Yang, Wen-Yan Dong, Hui-Min Yang, Li Zhang, Zhen-Hai Liang

Journal of Electrochemistry

Binary metal mixed oxides of Co and Cr with nominal compositional formulas, CoxCr1-xO3/2 (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0), were obtained by thermal decomposition method. The morphologies, crystal forms and valence states of the catalyst powders were analyzed by SEM, XRD and XPS, respectively. And the electrochemical properties, overpotentials and stabilities of CoxCr1-xO3/2 electrodes for oxygen evolution reaction (OER) in an alkaline solution were evaluated by linear sweep voltammetry (LSV), staircase voltammetry and chronoamperometry, respectively. The results indicated that the mixtures of Co3O4 and eskolaite-Cr2 …

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Synthesis And Electrochemical Properties Of Cnts/V2O5 Hollow Microspheres, Liang Hao, Lai-Fa Shen, Jie Wang, Jia-Jia Zhu, Xiao-Chen Zhao, Xiao-Gang Zhang Apr 2015

Synthesis And Electrochemical Properties Of Cnts/V2O5 Hollow Microspheres, Liang Hao, Lai-Fa Shen, Jie Wang, Jia-Jia Zhu, Xiao-Chen Zhao, Xiao-Gang Zhang

Journal of Electrochemistry

The carbon nanotubes/vanadium oxides (CNTs/V2O5) hollow microspheres (VOC) were prepared via solvothermal process. The effects of the ratio for CNTs to V2O5 on the morphologies, structures and electrochemical performances were systemically investigated. The results indicate that CNTs dramatically enhanced the rate performances of VOC composite electrodes. When the ratio of CNTs is 7.1%, the VOC composite electrode exhibited the best electrochemical performance, which delivered a specific capacitance of 346 F·g-1 at 0.5 A·g-1 and maintained 75% at 8 A·g-1 in 5 mol L-1 LiNO3. A hybrid capacitor …

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Electrochemical Performance Of Coal2O4-Coated Lini1/3Co1/3Mn1/3O2, Ji-Jun Cai, Wang-Jun Cui, Bing Li, Yang-Yang Yu, Jin-Bao Zhao Apr 2015

Electrochemical Performance Of Coal2O4-Coated Lini1/3Co1/3Mn1/3O2, Ji-Jun Cai, Wang-Jun Cui, Bing Li, Yang-Yang Yu, Jin-Bao Zhao

Journal of Electrochemistry

A method to improve the electrochemical performance of LiNi1/3Co1/3Mn1/3O2 for high voltage lithium-ion battery by CoAl2O4 coating was present in this work. The effects of CoAl2O4 coatings on the structure and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were investigated in detail. The results show that CoAl2O4 forms a thin layer of 8 nm on the surface of LiNi1/3Co1/3Mn1/3O2 without destroying the structure of the core material. The CoAl2O4-coated LiNi1/3Co1/3Mn1/3O …

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Porous Co3O4 Hollow Nanospheres Cathode Catalyst For High-Capacity And Long-Cycle Li-Air Batteries, Tong Liu, Na Li, Qing-Chao Liu, Xin-Bo Zhang Apr 2015

Porous Co3O4 Hollow Nanospheres Cathode Catalyst For High-Capacity And Long-Cycle Li-Air Batteries, Tong Liu, Na Li, Qing-Chao Liu, Xin-Bo Zhang

Journal of Electrochemistry

In this paper, a high specific surface area of porous Co3O4 hollow nanospheres was successfully synthesized via hydrothermal carbonization at 140 °C, followed by calcination using cobalt nitrate hexahydrate (Co(NO3)2·6H2O), hexamethylenetetramine (HMT), sucrose, and sodium citrate (Na3C6H5O7). The porous Co3O4 hollow nanospheres consisted of nanoparticles with high specific surface area of mesoporous structure, and could provide active reaction sites for OER and ORR. When used as lithium-air battery cathode catalyst, the Co3O4/Super P (SP) electrode exhibited excellent cycle performance, resulting in high capacity and long life of lithium-air batteries.

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Electrodeposition Of Al-Mg Alloys From Acidic Alcl3-Emic-Mgcl2 Room Temperature Ionic Liquids, Rostomali M., P. Abbott Andrew, S. Ryder Karl Apr 2015

Electrodeposition Of Al-Mg Alloys From Acidic Alcl3-Emic-Mgcl2 Room Temperature Ionic Liquids, Rostomali M., P. Abbott Andrew, S. Ryder Karl

Journal of Electrochemistry

Electrodeposition of aluminium-magnesium alloys have been carried out onto platinum and copper cathodes from Lewis acidic aluminium(III) chloride-1-ethyl-3-methylimidazolium chloride ionic liquid containing magnesium(II) chloride by constant current and constant potential methods at room temperature. Magnesium content in the deposited alloy increases with increasing MgCl2 concentration in the ionic liquid and with increasing cathodic current density. The influences of various experimental conditions on electrodeposition and the morphology of the electrodeposited layers have been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDAX). On increasing the deposition current densities the dense, bright, adherent …

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Syntheses And Electrochemical Performances Of Li4Ti5O12 Anode Materials For Lithium Ion Battery, Yong-Long Zhang, Xue-Bu Hu, Yao-Qiong Wang, Dong-Hai Huang Apr 2015

Syntheses And Electrochemical Performances Of Li4Ti5O12 Anode Materials For Lithium Ion Battery, Yong-Long Zhang, Xue-Bu Hu, Yao-Qiong Wang, Dong-Hai Huang

Journal of Electrochemistry

Series of spinel lithium titanate (Li4Ti5O12) materials were synthesized by one-step solid-state reaction using lithium acetate and TiO2 as raw materials under different temperatures (750/800/850 °C) and atmospheres (N2/air). The as-prepared Li4Ti5O12 materials were investigated by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, cyclic voltammotry and charge-discharge test to analyze their crystal structures, microstructures and electrochemical performances. The results show that the Li4Ti5O12（L-800N）material obtained at 800 °C under nitrogen atmosphere exhibited better electrochemical performance and smaller particle size. The initial …

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Electrochemical Conversion Reactions And Their Applications For Rechargeable Batteries, Ting Li, Han-Xi Yang Apr 2015

Electrochemical Conversion Reactions And Their Applications For Rechargeable Batteries, Ting Li, Han-Xi Yang

Journal of Electrochemistry

Electrochemical conversion reactions have received considerable interest as a new redox mechanism for constructing high capacity electrodes of rechargeable batteries. Without strict restrictions on the crystalline structure of the host lattice and the size of the associated ions, conversion reactions can take place in a variety of different metal compounds with different metal cations and deliver much higher reversible capacities through full utilization of all the oxidation states of the transition-metal compounds, opening up a new avenue for developing high capacity materials of rechargeable batteries. This paper briefly reviews the state of the art and challenges of conversion electrodes and …

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A Platinum-Hydrogen Reference Micro-Electrode For All Vanadium Redox Flow Battery, Zhi-Bin Lin, Yan-Qing Dong, Ming-Sen Zheng, Quan-Feng Dong Apr 2015

A Platinum-Hydrogen Reference Micro-Electrode For All Vanadium Redox Flow Battery, Zhi-Bin Lin, Yan-Qing Dong, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

A platinum-hydrogen reference micro-electrode was made with electroplating Pd on the surface of Pt wire and then coating anion membrane material. This reference electrode was built-in the porous electrode of the all vanadium redox flow batteries (VRFB), and monitored the charging /discharging and self-discharging of the VRFB. The results indicated that the capacity fading of VRFB occurred due to the graduate reduction of V(IV) active species in the electrolyte and the accumulation of V(V) in the positive electrode, leading to nonequilibrium of active species between the positive and negative electrodes.

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Living On Highways, Alexa Dicken Apr 2015

Living On Highways, Alexa Dicken

Binghamton University Undergraduate Journal

“Living on Highways” is a selection comprised of ten poems from my honors thesis. The poems focus on nature and views of human reality in the context of nature, two subjects that require attention to sustainability. I find my strongest inspiration in experiences of interaction with nature, simply being outside and observing the relationship between people and nature. Written in the environmental literary tradition of poets such as Billy Collins and Emily Dickinson, “Living on Highways” situates its poems within the context of nature but comes with a focused regard on humanity’s responsibility toward the appreciation of the environment and …

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Performance Study Of A Mems Low-Noise Sound Pressure Gradient Microphone Under An Ac Bias, Jonathan Michelson Apr 2015

Performance Study Of A Mems Low-Noise Sound Pressure Gradient Microphone Under An Ac Bias, Jonathan Michelson

Binghamton University Undergraduate Journal

An AC bias was introduced into microelectromechanical system (MEMS) low-noise sound pressure gradient microphone by Miles, Cui, Su and Hormentcovschi (2014), and its implications for the device's noise performance and directivity readings are discussed. The schematic involved demodulation of the microphone output with external circuitry, and subsequent computer software analysis of the microphone and circuitry outputs. Although insights into noise improvement were frustrated due to subpar noisy components used in the demodulation circuitry, the simultaneous measuring of the microphone's varying directivity patterns was shown to be achievable with this AC bias scheme.

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Orgin Of Subgap Features In Transparent Amorphous Oxide Semiconductors, Zachary Lebens-Higgins, Anne Dailey, Louis Piper Apr 2015

Orgin Of Subgap Features In Transparent Amorphous Oxide Semiconductors, Zachary Lebens-Higgins, Anne Dailey, Louis Piper

Binghamton University Undergraduate Journal

Amorphous indium gallium zinc oxide (a-IGZO) is a transparent amorphous oxide semiconductor (TAOS) that has shown promise as transparent thin film transistors (TTFTs) in various display applications. Within a-IGZO films, states can form in the band gap that hinder TTFT performance. In order to elucidate the origin of these states, we examined the formation of the subgap states for a-IGZO thin films with various compositions. We observed a positive correlation between the subgap formation and the percentage of oxygen ruling out oxygen deficiencies as a factor in the formation of subgap states. Furthermore, metallic indium crystallites were observed to form …

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The Economic Payoff Of Party Membership In China, Kevin Acker Apr 2015

The Economic Payoff Of Party Membership In China, Kevin Acker

Binghamton University Undergraduate Journal

Because political party membership could potentially confer large economic benefits, economists have increasingly turned their attention to the role of political and social status in one’s life. The Chinese Communist party is the biggest political party in the world, and members are often motivated to join for economic reasons. Previous studies examine the relationship between Communist party membership and earnings and find positive correlation but this correlation may be partly or totally spurious, thereby generating upwards-biased estimates of the importance of political party membership – political party membership is likely to be correlated with a variety of other variables, which …

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Residue, Donovan Borger Apr 2015

Residue, Donovan Borger

Binghamton University Undergraduate Journal

Residue is a flash fiction piece, exploring loss, specifically the loss of the protagonist’s sons and his teeth. To write this piece, I read a large number of anthologized flash fiction pieces written by contemporary authors including David Foster Wallace, Lydia Davis, Tobias Wolff, and George Saunders with the intent of understanding and reproducing their takes on the flash fiction form while adding my own nuances. For purposes of characterization and setting, I also researched logging done on the land of what is now Algonquin Park in Ontario. My research and writing show that flash fiction functions most effectively when …

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Morality Of A Carbon Tax: Transition To A Sustainable Economy, Timothy Lamendola Apr 2015

Morality Of A Carbon Tax: Transition To A Sustainable Economy, Timothy Lamendola

Binghamton University Undergraduate Journal

A carbon tax is needed to address the negative externalities caused by carbon emissions. Increased carbon dioxide concentrations in the atmosphere have a direct and negative impact on net social benefit to current and future generations. Our current human population has a moral obligation to future generations and, therefore, is responsible for excess burning of fossil fuels. This essential carbon tax is needed to help wean humans off their fossil fuel reliance. One should not be concerned with the economic losses this could cause because an economy based off unlimited growth is unsustainable and must be altered. A new, sustainable …

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Numerical Model Derived Altimeter Correction Maps For Non-Standard Atmospheric Temperature And Pressure, Thomas A. Guinn, Frederick R. Mosher Apr 2015

Numerical Model Derived Altimeter Correction Maps For Non-Standard Atmospheric Temperature And Pressure, Thomas A. Guinn, Frederick R. Mosher

International Journal of Aviation, Aeronautics, and Aerospace

Altimeter corrections for non-standard temperature pose a challenge because accurate calculations require detailed knowledge of the temperature structure of the atmosphere between the surface and the aircraft. By applying basic hypsometric formulae to high resolution numerical model temperature and moisture output, detailed maps of current and forecasted corrected D-values are created. Corrected D-values provide the altitude difference between the true altitude and the indicated altitude from a pressure altimeter. Unlike standard D-values, the corrected D-value corrects for non-standard pressure in addition to non-standard temperature and is therefore useful for flights below class A airspace. Maps of corrected D-value may help …

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Diffusion In A Solid Cylinder Part I: Advancing Model, Cho-Liang Tsai, Ching-Chang Lin Apr 2015

Diffusion In A Solid Cylinder Part I: Advancing Model, Cho-Liang Tsai, Ching-Chang Lin

Journal of Marine Science and Technology–Taiwan

An advanced diffusion model is used to calculate the concentration of a substance diffused in a solid cylindrical medium. The mathematical process in this study adopts Neumann’s algorithm for applying the advancing model to revise the solution derived by Carslaw and Jaeger. The modified solution clearly indicates a diffusion front which does not exist in the original model. Calculating the diffusion depth becomes possible and is novel for a solid cylindrical medium. The major contribution of this study is the application of the advancing model to solve the diffusion problem of a cylindrical medium in cylindrical coordinate system.

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A Linearly Constrained Signal Subspace Projection Approach Developed To Detect Targets In Hyperspectral Images, Zay-Shing Tang, Lena Chang, Hsien-Sen Hung Apr 2015

A Linearly Constrained Signal Subspace Projection Approach Developed To Detect Targets In Hyperspectral Images, Zay-Shing Tang, Lena Chang, Hsien-Sen Hung

Journal of Marine Science and Technology–Taiwan

Hyperspectral images have been widely used for target detection. In general, target signatures should be known a priori for filter-based detection methods. However, the uncertainty of target signatures caused by the influence of atmospheric interference or other random noise degrades the detection performance. Therefore, developing a robust detection method is crucial in hyperspectral image analysis. In this study, a linearly constrained signal subspace projection approach for target detection is proposed. Instead of using a single constraint on target detection, an optimal filter with multiple constraints is designed using signal subspace projection (SSP). The SSP approach fully exploits the orthogonal property …

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Voltage Sag Planning Of A Power System With Specially Connected Transformers Using Hybrid Differential Evolution Considering Iti Curve, Yao-Hung Chan, Chi-Jui Wu, Ying-Pin Chang Apr 2015

Voltage Sag Planning Of A Power System With Specially Connected Transformers Using Hybrid Differential Evolution Considering Iti Curve, Yao-Hung Chan, Chi-Jui Wu, Ying-Pin Chang

Journal of Marine Science and Technology–Taiwan

This paper outlines the voltage sag planning of a power system with a three-phase to two-phase transformer. We compared systems with V-V and Scott connection schemes using the hybrid differential evolution (HDE) method to determine the design parameters by taking into account the ITI curves and coordination of over-current relays. The proposed model comprises a node admittance matrix for the calculation of voltage sag in order to determine the severity of system sag after single or two-phase faults. These analytical equations are useful in the mathematical determination of optimal design parameters. We also used the proposed method to obtain suitable …

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Experimental Study Of Seismic Performances Of Rc Bridge Columns With Cfst Column Embedded Lnside, Wen-Liang Qiu, Chin-Sheng Kao, Chang-Huan Kou, Jeng-Lin Tsai Apr 2015

Experimental Study Of Seismic Performances Of Rc Bridge Columns With Cfst Column Embedded Lnside, Wen-Liang Qiu, Chin-Sheng Kao, Chang-Huan Kou, Jeng-Lin Tsai

Journal of Marine Science and Technology–Taiwan

To improve the seismic performances of reinforced concrete (RC) bridge columns and to prevent columns from shear failure and core concrete crushing, high strength concrete filled steel tube (CFST) is put into RC columns to form a new kind of composite column. Through cyclical loading tests, the seismic performances of four columns are studied. The first column tested is a conventional RC column, the second one is a bonded composite column, the third one is an unbonded composite column, and the fourth one is an unbonded composite column whose axial force is composed of only bone by its CFST column. …

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An O(T2) Boundary Layer In Sliding Mode For Time-Delay Systems, Ming-Chang Pai Apr 2015

An O(T2) Boundary Layer In Sliding Mode For Time-Delay Systems, Ming-Chang Pai

Journal of Marine Science and Technology–Taiwan

A new discrete-time integral sliding mode control scheme is proposed for a class of linear multi-input systems with state delays. Based on the Lyapunov stability theory and one-step delayed disturbance approximation, a sliding mode controller not only drives the sliding mode into the O(T2 ) boundary, but also achieves the O(T2 ) boundary for state regulation. A novel integral sliding surface is introduced so that reaching phase is eliminated. Chattering phenomenon is eliminated and the knowledge of upper bound of external disturbances is not required. The validity of the proposed control methodology is demonstrated by simulation results.

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Numerical Simulation Of Water Entry Of Wedges Based On The Cip Method, Zhao-Yu Wei, He-Ye Xiao, Zhi-Dong Wang, Xiu-Hua Shi Apr 2015

Numerical Simulation Of Water Entry Of Wedges Based On The Cip Method, Zhao-Yu Wei, He-Ye Xiao, Zhi-Dong Wang, Xiu-Hua Shi

Journal of Marine Science and Technology–Taiwan

The hydrodynamic problems for water entry of wedges are studied by a constrained interpolation profile (CIP) based on Cartesian grid method. The CIP scheme was applied to the Cartesian grid based on flow solver, which was first described. The tangent of hyperbola for interface capturing (THINC) scheme was applied to capture the free surface. The CIP method was extended to capture the dynamics in the water entry approach. The simulations were performed in three aspects. First, pressure distributions for the wedges entering into water with constant speed were predicted, and the results were compared with the similarity solutions by the …

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Robust Bearing Estimation In Shallow Water Using Vector Optimization, Hai-Yan Song, Jie Shi, Chang-Yi Yang, Bo-Sheng Liu, Ming Diao Apr 2015

Robust Bearing Estimation In Shallow Water Using Vector Optimization, Hai-Yan Song, Jie Shi, Chang-Yi Yang, Bo-Sheng Liu, Ming Diao

Journal of Marine Science and Technology–Taiwan

Correlated multi-paths may cause a biased bearing estimation in shallow water, so most existing methods make fully use of the multi-path nature and the underwater channel property to provide an unbiased bearing estimation. However, an imprecise knowledge of the underwater channel parameters or the array model mismatches will cause performance degradation, especially for the high-resolution methods. Therefore development of robust bearing estimation methods in shallow water is critically important. In this paper, a new approach to robust bearing estimation is proposed in the presence of underwater channel parameter uncertainties or array model mismatches. The proposed method is based on the …

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Solving The Inverse Cauchy Problem Of The Laplace Equation Using The Method Of Fundamental Solutions And The Exponentially Convergent Scalar Homotopy Algorithm (Ecsha), Weichung Yeih, I-Yao Chan, Cheng-Yu Ku, Chia-Ming Fan Apr 2015

Solving The Inverse Cauchy Problem Of The Laplace Equation Using The Method Of Fundamental Solutions And The Exponentially Convergent Scalar Homotopy Algorithm (Ecsha), Weichung Yeih, I-Yao Chan, Cheng-Yu Ku, Chia-Ming Fan

Journal of Marine Science and Technology–Taiwan

In this paper, the inverse Cauchy problem of the Laplace equation is considered. Using the method of fundamental solutions, a system of linear algebraic equations can be obtained by satisfying the Cauchy boundary conditions on the overprescribe boundary points. The resulting linear algebraic equation is ill-posed and is treated by the exponentially convergent scalar homotopy algorithm (ECSHA). Four examples are adopted to show the validity of the proposed numerical scheme and it is concluded that the current approach can successfully resolve the ill-posedness of the inverse Cauchy problem even when the noise exists.

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Nonlinear Breaker Characteristics And Impulse On A Sloping Bottom, Wen-Jer Tseng Apr 2015

Nonlinear Breaker Characteristics And Impulse On A Sloping Bottom, Wen-Jer Tseng

Journal of Marine Science and Technology–Taiwan

This paper presents an experimental and theoretical investigation of nonlinear surface-wave propagation over a sloping bed. First, a second-order analytical solution for nonlinear surface-wave propagation over a sloping bed is derived using a perturbation method for the bottom slope  and the wave steepness  in an Eulerian system. Then, by transforming the flow field solution from an Eulerian system into a Lagrangian system, more accurate wave profiles are determined. New theoretical breaker characteristics and breaker impulses are derived using the kinematic stability parameter. Subsequently, a series of experiments to measure breaker characteristics and the breaker impulse are conducted in …

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Effects Of The Cathodic Current On Alkali-Silica Aggregate Reaction, Jiang-Jhy Chang, Weichung Yeih, Cheng-Chin Chang Apr 2015

Effects Of The Cathodic Current On Alkali-Silica Aggregate Reaction, Jiang-Jhy Chang, Weichung Yeih, Cheng-Chin Chang

Journal of Marine Science and Technology–Taiwan

In this study, we investigated whether the cathodic current accelerates the alkali-silica aggregate reaction. Variables considered were the water/cement (w/c) ratio, initial alkali content, and cathodic current. The crack initiation time, crack mouth opening history, and microhardness values were monitored to examine the effect of the cathodic current on crack initiation and propagation due to the alkali-silica aggregate reaction. In addition, chemical titration was performed to determine the amount of accumulated sodium and potassium ions to support our viewpoints. The results showed that the crack initiation time shortened with an increase in the initial alkali content, w/c ratio, and/or cathodic …

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