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Mixed nonlinear dynamic voltage phasor tracing method based on WAMS/SCADA

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 868-876页

作者： Xiao-gang CHEN yong-hui yi Wei WANG Quan-yuan JIANG Chuang-xin GUO yi-jia CAO School of Electrical Engineering Zhejiang University Hangzhou 310027 China Hangzhou Electric Power Bureau Hangzhou 310009 China Zhejiang Provincial Electric Power Company Hangzhou 310007 China

By considering the static voltage characteristic of the load, we propose a WAMS/SCADA mixed nonlinear method to estimate the voltage of unobservable buses caused by topology change or phasor measurement unit (PMU) malfunction in a power system. By modeling the load characteristic with data from SCADA, we employed the Gauss-Seidel method to solve the nonlinear equations and estimate the voltage of unobservable buses with the high precision voltages of neighboring buses measured by a PMU. Simulations were carried out on the IEEE 39-bus system, and the results show that this novel method can dynamically and accurately trace the variation of the voltage phasor of the unobservable buses.

关键词： Wide area measurement system (WAMS) Supervisory control and data acquisition (SCADA) system Observability Dynamic tracing Nonlinear equation

A Method with Parameter for Solving the Spectral Radius of Nonnegative Tensor

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Journal of the Operations Research Society of China 2017年第1期5卷 3-25页

作者： yi-yong Li Qing-Zhi Yang Xi He School of Mathematical Sciences and Lab of Pure Mathematics and Combinatic Nankai UniversityTianjin 300071China

In this paper,a method with parameter is proposed for finding the spectral radius of weakly irreducible nonnegative *** is more,we prove this method has an explicit linear convergence rate for indirectly positive ***,the algorithm is exactly the NQZ method(proposed by Ng,Qi and Zhou in Finding the largest eigenvalue of a non-negative tensor SIAM J Matrix Anal Appl 31:1090–1099,2009)by taking a specific ***,we give a modified NQZ method,which has an explicit linear convergence rate for nonnegative tensors and has an error bound for nonnegative tensors with a positive Perron ***,we promote an inexact power-type ***,some numerical results are reported.

关键词： Nonnegative tensor Indirectly positive tensors Linear convergence Perturbation Complexity

A Deblurring Procedure for Two-dimensional Small Angle X-ray Scattering Patterns

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Chinese Journal of Polymer Science 2016年第4期34卷 505-512页

作者： Ran Chen Zhi-yong yi Jia-xue Liu 刘震宇门永锋 State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

A general pre-processing procedure of the measured SAXS patterns for reducing the effect of beam stop and beam stop holder is described. A proper method for automatically choosing the regularization parameter is implemented. The method works out on the two-dimensional SAXS patterns. After deblurring, the corresponding two-dimensional patterns will be converted into one-dimensional integrated intensity distribution curves. We tested the program using both calculated artificial data and real experimental data such as polystyrene and poly（methyl methacrylate） latices. The deblurred results are satisfactory showing the effectiveness of the method. The deblurring process of a typical two-dimensional SAXS pattern using the Matlab based program can be completed in few seconds on normal personal computers.

关键词： Deblur PS latex PMMA colloidal dispersion SAXS.

DRILLING CHARACTERISTICS OF COMBINATIONS OF DIFFERENT HIGH PRESSURE JET NOZZLES

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Journal of Hydrodynamics 2011年第3期23卷 384-390页

作者： ZHANG Yu-ying LIU yong-wang XU yi-ji REN Jian-hua College of Petroleum Engineering China University of Petroleum （East China） Dongying 257061 China

The high speed fluid jet for directly or indirectly breaking rock is one of the most effective ways to improve the deep penetration rate. In order to maximize the efficiency of energy use, the flow characteristics of different combinations of high pressure jet nozzles are analyzed through numerical simulations. According to the velocity vectors at the bottom and the bottom hole pressure diagram, the effects of the high pressure nozzle combinations on the flow structure and the penetration rate are analyzed. It is shown that the combination of three vertical edge nozzles is very efficient, but inefficient in cleaning the bottom hole and eroding the wall. The jet velocity is 400 m/s and the radius is 5 mm, with a center nozzle added, the problem can be solved, but the high-pressure fluid displacement would increase. The center nozzle＇s jet velocity is 200 m/s and the radius is 8 ram, the combination of two vertical edge nozzles and a center tilt nozzle or that of a vertical edge nozzle and a center tilt nozzle would provide a flow structure favorable for drilling. The angle of inclination is 10°. To take advantage of high pressure jet energy to improve the efficiency of drilling, it is important to select a suitable nozzle combination according real conditions.

关键词： Rate Of Penetration (ROP) rock breaking high pressure jet nozzle combination numerical simulation energy use

Novel AC Servo Rotating and Linear Composite Driving Device for Plastic Forming Equipment

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Chinese Journal of Mechanical Engineering 2017年第4期30卷 843-853页

作者： Jin-Tao Liang Sheng-Dun Zhao yong-yi Li Mu-Zhi Zhu School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049China School of Mechano-electronic Engineering Xidian UniversityXi'an 710071China Beijing Institute of Space Launch Technology Beijing 100076China

The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.

关键词： Plastic forming Direct drive - Permanentmagnet motor Linear feeding Servo control

Early ultrasound diagnosis of conjoined twins at eight weeks of pregnancy: A case report

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World Journal of Clinical Cases 2020年第21期8卷 5389-5393页

作者： Xiao-Wen Liang yong-yi Cai Yao-Zhang Yang Zhi-yi Chen Department of Ultrasound Medicine The Third Affiliated Hospital of Guangzhou Medical UniversityGuangzhou 510000Guangdong ProvinceChina Department of Ultrasound Liwan Hospital of the Third Affiliated Hospital of Guangzhou Medical UniversityGuangzhou 510000Guangdong ProvinceChina

BACKGROUND Conjoined twins are a rare occurrence,and the majority of these malformations are detected during second trimester *** SUMMARY Herein we report a case of conjoined twins,which was diagnosed by ultrasound at 8 wk gestation and was normal at 7 wk *** two fetuses shared one heart and were diagnosed as thoracopagus *** is the first report of conjoined twins diagnosed at 8 wk *** pregnancy was terminated electively at 9 wk *** some congenital malformations can be diagnosed earlier,a prenatal ultrasound examination at an early gestational stage cannot be *** This case demonstrates that a 7-8 wk gestation might be the earliest period when conjoined twins can be diagnosed by ultrasound.

关键词： Conjoined twins Ultrasound Thoracopagus Early diagnosis Congenital malformation Case report

Two-dimensional Nitrogen-doped Mesoporous Carbon/Graphene Nanocomposites from the Self-assembly of Block Copolymer Micelles in Solution

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Chinese Journal of Polymer Science 2018年第3期36卷 266-272页

作者： Nan Wang Hao Tian Shu-Yan Zhu De-Yue Yan yi-yong Mai School of Chemistry and Chemical Engineering Shanghai Key Laboratory of Electrical Insulation and Thermal AgeingShanghai Jiao Tong University Shanghai 200240China

The self-assembly of block copolymer in solution has proven to be an effective strategy for building up a wide range of nanomaterials with diverse structures and *** paper reports a facile self-assembly approach towards two-dimensional(2D)sandwich-like mesoporous nitrogen-doped carbon/reduced graphene oxide nanocomposites(denoted as mNC/rGO)with well-defined large *** strategy involves the synergistic self-assembly ofpolystyrene-block-poly(ethylene oxide)(PS-b-PEO)spherical micelles,m-phenylenediamine(mPD)monomers and GO in solution and the subsequent carbonization at 900~*** resultant mNC/rGO nanosheets have an average pore size of 19 nm,a high specific surface of 812 m^(2)'g^(-1)and a nitrogen content of 2.2 wt%.As an oxygen reduction reaction(ORR)catalyst,the unique structural features render the metal-free nanosheets excellent electrocatalytic *** a 0.1 mol.L-~KOH alkaline medium,mNC/rGO exhibits a four-electron transfer pathway with a high half-wave-potential(El/2)of+0.77 V versus reversible hydrogen electrode(RHE)and a limiting current density(JL)of 5.2 mA'cm^(-2),which are well comparable with those of the commercial Pt/C catalysts.

关键词： Block copolymer Self-assembly 2D materials Mesoporous carbon ORR

Synthesis of Novel Chitosan Microspheres Grafted with β-Cyclodextrins and Their Adsorption for Iodine for Antibacterial Activities

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Wuhan University Journal of Natural Sciences 2005年第3期10卷 591-596页

作者： yiying WANGYu-ting ZHANGXue-yong PANGZhi-yi PENGQi LIUHui CollegeofResourcesandEnvironmentalSciences WuhanUniversityWuhan430072HubeiChina

The novel chitosan microspheres grafted with beta-cyclodextrins (CMGC) wereprepared by means of the reaction of chitosan microspheres and mono-(6-p-tosyl)- beta-cyclodextrins(beta-CD-OTs-6). beta-CD-OTs-6 were gained by the reaction of p-toluenesul-fonyl chloride (TsCl) andbeta-cyclodextrins (beta-CDs). Their structures were proved by Fourier transform infrared spectralanalysis (FT-IR), X ray powder diffraction analysis, and ^(13)C NMR; the configuration of CMGC wascharacterized by scanning electron micrograph (SEM) and transmittance electron micrograph (TEM). Theinclusion complex of CMGC with iodine was prepared and its inclusion ability was studied. Theexperimental results showed that some iodine was included with CMGC and formed a stable *** stable complex of CMGC and iodine (CMGC-1) shows good antibacterial effect.

关键词： beta-cyclodextrin chitosan microspheres iodine anti-bacteria

Lipase and photodecarboxylase coexpression: A potential strategy for alkane-based biodiesel production from natural triglycerides

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Chinese Journal of Chemical Engineering 2024年第3期67卷 238-246页

作者： yong-yi Zeng Xin-yi Xu Jin-Xuan Xie Wen-Li Chen Lan Liu Xin-Jian yin Bi-Shuang Chen School of Marine Sciences Sun Yat-Sen UniversityZhuhai 519080China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China

Alkane-based biodiesel is considered the next generation of biodiesel owing to its potential environmental benefits and the fact that it exhibits much higher specific caloric values than traditional ***,the formidable obstacle impeding the commercialization of this cutting-edge fuel alternative lies in the cost associated with its *** this study,an engineered strain Escherichia coli(***)showcasing harmonized coexpression of a lipase(from Thermomyces lanuginosus lipase,TLL)and a fatty acid photodecarboxylase(from Chlorella variabilis,CvFAP)was first constructed to transform triglycerides into *** potential of *** BL21(DE3)/pRSFDuet-1-TLL-CvFAP for alkane synthesis was evaluated with tripalmitin as a model substrate under various process *** a comprehensive examination of the reaction parameters,the scope of the biotransformation was expanded to‘real’substrates(vegetable oils).The results showed that bioderived oils can be transformed into alkanes with high yields(0.80-10.20 mmol·L^(-1))under mild conditions(35℃,pH 8.0,and 36 h)and blue light *** selected processes were performed on an increased lab scale(up to 100 ml)with up to 24.77 mmol·L^(-1) tripalmitin,leading to a yield of 18.89 mmol·L^(-1) *** the employment of a method for efficiently producing alkanes under mild conditions and a simple procedure to isolate alkanes from the reaction system,the utilization of sustainable biomass as a fundamental feedstock emerges as the primary solution to lower the cost of alkane-based ***,this study proposes a readily implementable and highly effective approach for alkane-based biodiesel production.

关键词： Alkane-based biodiesel Renewable biomass Co-overexpression Lipase Photodecarboxylase