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A Study of Wind Statistics Through Auto-Regressive and Moving-Average (ARMA) Modeling

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China Ocean Engineering 2001年第1期16卷 61-72页

作者： john z.yim(尹彰) ChunRen CHOU(周宗仁) Department of Harbour and River Engineering National Taiwan Ocean University Keelung 20224 China Department of Harbour and River Engineering National Taiwan Ocean University Keelung 20224 China

Statistical properties of winds near the Taichung Harbour are investigated. The 26 years'incomplete data of wind speeds, measured on an hourly basis, are used as reference. The possibility of imputation using simulated results of the Auto-Regressive (AR), Moving-Average (MA), and/ or Auto-Regressive and Moving-Average (ARMA) models is studied. Predictions of the 25-year extreme wind speeds based upon the augmented data are compared with the original series. Based upon the results, predictions of the 50- and 100-year extreme wind speeds are then made.

关键词： Auto-Regressive and Moving-Average (ARMA) modeling probability distributions extreme wind speeds

Experimental Investigation of Wave Heights in A Directional Wave Field Through Image Sequences

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China Ocean Engineering 2005年第1期19卷 37-48页

作者： Chung-Ren CHOU Teng-Wei LIN Ruey-Syan SHIH john z. yima Department of Harbor and River Engineering National Taiwan Ocean UniversityKeeling 20299 ChinaDepartment of Harbor and River Engineering National Taiwan Ocean UniversityKeeling 20299 ChinaDepartment of Civil Engineering Tung Nan Institute of Technology Taipei 22202 ChinaDepartment of Harbor and River Engineering National Taiwan Ocean UniversityKeeling 20299 China

Measurements of wave heights with image sequences from a Charged Coupled Device(CCD) camera were made. Sinusoidal, as well as unidirectional and directional, waves were used for the experiments. A transfer function was obtained by calibration of the magnitudes of the gray values of the images against the results of wave gauge measurements for directional waves. With this transfer function, wave heights for regular waves were deduced. It is shown that the average relative errors are smaller than 16% for both unidirectional and directional waves.

关键词： charged coupled device remote sensing directional wave transfer function wave height measurements

An efficient method for computing excess free energy of liquid

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Science China Chemistry 2018年第1期61卷 135-140页

作者： Jianing Song Linqiong Qiu john z.H. z.ang School of Chemistry and Molecular Engineering East China Normal University Shanghai 200062 China NYU-ECNU Center for Computational Chemistry at NYU ShanghaL Shanghai 200062 China State Key Laboratory of Precision Spectroscopy East China Normal University Shanghai 200062 China Department of Chemistry New York University NY NY 10003 USA

We present a new theoretical method for efficient calculation of free energy of liquid. This interaction entropy method allows one to compute entropy and free energy of liquid from standard single step MD(molecular dynamics) simulation directly in liquid state without the need to perform MD simulations at many intermediate states as required in thermodynamic integration or free energy perturbation methods. In this new approach, one only needs to evaluate the interaction energy of a single(fixed) liquid molecule with the rest of liquid molecules as a function of time from a standard MD simulation of liquid and the fluctuation of distribution of this interaction energy is then used to calculate the interaction entropy of the liquid. Explicit theoretical derivation of this interaction entropy approach is provided and numerical calculations for the benchmark liquid water system were carried out using three different water models. Numerical analysis of the result was performed and comparison of the computational result with experimental data and other theoretical results were provided. Excellent agreement of calculated free energies with the experimental data using TIP4 P model is obtained for liquid water.

关键词： excess free energy liquid MD simulation interaction entropy

Calcium Phosphate Biomaterials: An Update

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Journal of Wuhan University of Technology(Materials Science) 2005年第B12期20卷 1-6页

作者： Racquel z.LeGeros john P LeGeros New York University College of Dentistry New York 10010 USA

Current calcium phosphate （ CaP ） biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite （ HA ） from synthetic or biologic origin, beta-tricaicium phosphate （ β- TCP ）, biphasic calcium phosphate （BCP）, and are available as granules, porous blocks, components of compashes （CaP/pollymer） cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3^- and F-substituted apatites, Mg-and z.-substituted β-TCP, calcium phosphate glasses, This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity , osteoconductivity , osteoinductivity.

关键词： calcium phosphates HA β- TCP BCP calcium phosphate cement implant coatings bonegrafts

Professor z.ao-Yin Wang,Ph.D.,*** Editor-in-Chief of the International Journal of Sediment Research

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International Journal of Sediment Research 2014年第1期29卷 133-134页

作者： john z.Shi Hong-Wei Fang Shanghai Jiao Tong University Tsinghua University

(January 1998-December 2013)Current developments in sediment research continue at a heady pace,and are reported in the International Journal of Sediment Research(IJSR)at about 500 pages per ***,as of January 2014,a major change has occurred:after16 years(January 1998 to December 2013)as Editor-in-Chief,Professor z.ao-Yin Wang has stepped down from the handling of manuscripts.

关键词： Wang M.ASCE Editor-in-Chief of the International Journal of Sediment Research Professor z.ao-Yin Wang,Ph.D

Asymmetrical Fault Current Calculation Method and Influencing Factors Analysis of Droop-Controlled Inverters

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 562-573页

作者： Huimin z.ao z.ikang Shuai Jun Ge An Luo Weimin Wu z.john Shen College of Electrical and Information Engineering Hunan UniversityChangsha 410006China Electrical Engineering Department Shanghai Maritime UniversityShanghai 201306China Department of Electrical and Computer Engineering Ilinois Institute of TechnologyChicagoIL 60616 USA

Since the fault dynamic of droop-controlled inverter is different from synchronous generators (SGs), protection devices may become invalid, and the fault overcurrent may damage power electronic devices and threaten the safety of the microgrid. Therefore, it is imperative to conduct a comprehensive fault analysis of the inverter to guide the design of protection schemes. However, due to the complexity of droop control strategy, existing literatures have simplified asymmetric fault analysis of droop-controlled inverters to varying degrees. Therefore, accurate fault analysis of a droop-controlled inverter is needed. In this paper, by analyz.ng the control system, an accurate fault model is established. Based on this, a calculation method for instantaneous asymmetrical fault current is proposed. In addition, the current components and current characteristics are analyz.d. It was determined that fault currents are affected by control loops, fault types, fault distance and nonlinear limiters. In particular, the influences of limiters on the fault model, fault current calculation and fault current characteristics were analyz.d. Through detailed analysis, it was found that dynamics of the control loop cannot be ignored, the fault type and fault distance determine fault current level, and part of the limiters will totally change the fault current trend. Finally, calculation and experimental results verify the correctness of the proposed method.

关键词： Asymmetrical fault analysis droop control fault current calculation method limiter transient fault characteristics

Interaction specific binding hotspots in Endonuclease colicin-immunity protein complex from MD simulations

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Science China Chemistry 2013年第8期56卷 1143-1151页

作者： YAO XueXia JI ChangGe XIE DaiQian z.ANG john z.H. School of Chemistry and Chemical Engineering Nanjing University College of Engineering Nanjing Agricultural University State Key Laboratory of Precision Spectroscopy Department of PhysicsEast China Normal University Department of Chemistry New York University

The binding of Endonuclease colicin 9 (E9) by Immunity protein 9 (Im9) was found to involve some hotspots from helix III of Im9 on protein-protein interface that contribute the dominant binding energy to the *** the current work,MD simulations of the WT and three hotspot mutants (D51A,Y54A and Y55A of Im9) of the E9-Im9 complexes were carried out to investigate specific interaction mechanisms of these three hotspot *** changes of binding energy between the WT and mutants of the complex were computed by the MM/PBSA method using a polariz.d force field and were in excellent agreement with experiment values,verifying that these three residues were indeed hotspots of the binding *** decomposition analysis revealed that binding by D51 to E9 was dominated by electrostatic interaction due to the presence of the carboxyl group of Asp51 which hydrogen bonds to *** binding by hotspots Y54 and Y55,van der Waals interaction from the aromatic side chain of tyrosine provided the dominant *** comparison,calculation by using the standard (nonpolariz.ble) AMBER99SB force field produced binding energy changes from these mutations in opposite direction to the experimental *** hydrogen bond analysis showed that conformations sampled from MD simulation in the standard AMBER force field were distorted from the native state and they disrupted the inter-protein hydrogen bond network of the protein-protein *** current work further demonstrated that electrostatic polariz.tion plays a critical role in modulating protein-protein binding.

关键词： protein-protein interaction binding hotspot mutation Endonuclease Colicin immunity protein MD simulation

SiC JFETs Modular Cascaded Method with Active Clamp Control Strategy for DC Solid-state Circuit Breaker

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CSEE Journal of Power and Energy Systems 2023年第6期9卷 2435-2446页

作者： Hong Duan Wei Wang z.ikang Shuai Dong He Daixin Chen z.john Shen the College of Electrical and Information Engineering Hunan UniversityChangsha 410006China the Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616 USA.

Power semiconductor devices cascaded topology is one of the most common solutions for solid-state circuit breakers(SSCBs)working in medium-voltage DC ***,when the number of cascaded devices is large,current series technologies of power semiconductor devices will be difficult to be applied since with uneven voltage sharing ***,this paper proposes a novel cascade method of multi-SiC JFETs based on modules *** method consists of two parts:one is a single-gate driver cascaded SiC JFETs topology which is used to form the module,the other one is an active clamp control strategy which ensures that each module is protected from overvoltage when modules are *** proposed cascade method can effectively suppress voltage overshoot of cascading power devices in the switching *** on the proposed cascade method,a 5kV/63A SSCB prototype is ***,an experiment is conducted based on the designed *** results validate the effectiveness of the proposed cascaded method for SSCB.

关键词： Active control clamp DC solid-state circuit breaker modular SiC JFETs series connection

Transient Characteristics and Accommodative Current Limiting Strategy for Bidirectional Interlinking Converters in Hybrid AC/DC Microgrids

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1575-1588页

作者： Xia Shen z.ikang Shuai Wen Huang Chao Shen Yang Shen z.john Shen College of Electrical and Information Engineering Hunan UniversityChangsha 410082China Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616 USA

Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC ***,the variety of control modes and flexible bidirectional power flow complicate the influence of AC faults on BIC itself and on DC sub-grid,which potentially threaten both converter safety and system *** study first investigates AC fault influence on the BIC and DC bus voltage under different BIC control modes and different pre-fault operation states,by developing a mathematical model and equivalent sequence ***,based on the analysis results,a general accommodative current limiting strategy is proposed for BIC without limitations to specific mode or operation *** amplitude is predicted and constrained according to the critical requirements to protect the BIC and relieving the AC fault influence on the DC bus *** with conventional methods,potential current limit failure and distortions under asymmetric faults can also be ***,experiments verify feasibility of the proposed method.

关键词： Bidirectional interlinking converter current limiting fault characteristic hybrid AC/DC microgrid variation/oscillation of DC bus voltage