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Double Grating Expanders for Fourth-Order Dispersion Compensation in Chirped Pulse Amplifiers

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Chinese Physics Letters 2013年第4期30卷 99-101页

作者： WANG Cheng leng Yu-Xin State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800

A scheme of double grating expanders is first proposed for high energy chirped pulse *** is demonstrated that they can compensate for the amplifier's material dispersion up to the fourth-order,together with a suitable grating *** scheme makes it possible that the pulse expansion in Chirped pulse amplifiers(CPAs)is no longer restricted by the material dispersion,and the corresponding grating compressor can be independently optimized according to the available gratings'size and damage threshold.

关键词： amplifier compressor dispersion

Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacifi c diagnosed by ECCO2

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Journal of Oceanology and Limnology 2022年第3期40卷 870-890页

作者： Jie WANG Xuezhi BAI Hengling leng College of Oceanography Hohai UniversityNanjing 210098China Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210098China

Seasonal variations of the equatorial undercurrent(EUC) termination in the Eastern Pacific,and their mechanism were examined using the Estimating the Circulation and Climate of the Ocean,PhaseⅡ(ECCO2).The ECCO2 reproduced a weak and shallow eastward EUC east of the Galapagos Islands,with annual mean transport of half of EUC to the west of the *** diagnosis of zonal momentum equation suggests that the zonal advection(nonlinear terms) drives the EUC beyond the Islands rather than the pressure gradient *** EUC in the Far Eastern Pacific has the large st core velocity in boreal spring and the smallest one in boreal summer,and its volume transport exhibits two maxima in boreal spring and *** seasonal variability of the EUC in the Eastern Pacific is dominated by the Kelvin and Rossby waves excited by the zonal winds anomalies in the central and Eastern Pacific that are associated with the seasonal relaxation or intensification of the trade *** the Far Eastern Pacific to the east of 120°W,the eastward propagation Kelvin waves play a dominate role in the seasonal cycle of the EUC,results in a semiannual fluctuation with double peaks in boreal spring and autumn.A construction of water mass budget suggests that approximately 24.1% of the EUC water east of 100°W has upwelled to the mixed layer by0.35 m/*** estimated upwelling is stronge st during boreal autumn and weake st during boreal *** is also found that approximately 42.6% of the EUC turns westward to feed the south equatorial current(SEC),13.2% flows north of the equator,and 20.1% flows south of the equator,mainly contributing to Peru-Chile undercurrent.

关键词： equatorial undercurrent termination Eastern Pacific Ocean Estimating the Circulation and Climate of the Ocean,Phase II(ECCO2) Peru-Chile undercurrent Galapagos Islands

Surface properties of nitrogen-ion-implanted TiNi shape memory alloy

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Journal of University of Science and Technology Beijing 2006年第2期13卷 154-157页

作者： Chongyan leng Teruo Asaoka Rong Zhou School of Materials and Metallurgical Engineering Kunming University of Science and Technology Kunming 650093 China Department of Intelligent and Mechanical Engineering Tokyo Denki University Hatoyama Hiki-Gun Saitama 350-0394 Japan School of Mechanical Engineering Kunming University of Science and Technology Kunming 650093 China

X-ray diffraction （XRD）, auger electron spectroscopy （AES）, and X-ray photoelectron spectroscopy （XPS） were used to characterize the surface properties of the N^ ＋-ion-implanted TiNi alloy. There is a high nitrogen content region at the outermost surface of the N^＋-ion-implanted TiNi alloy. The detected nitrogen exists mainly in the form of TiN. Small amounts of Ti305 and TiO2 also exist on the surface of the N^＋-ion-implanted TiNi sample. The modified layer of the N^＋-ion-implanted sample can work as an obstacle layer of the nickel＇s dissolution, which obstructs Ni dissolving from the TiNi surface effectively.

关键词： shape memory alloys TiNi surface properties

4D printed shape memory polymers and their structures for biomedical applications

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Science China(Technological Sciences) 2020年第4期63卷 545-560页

作者： LI YueJia ZHANG FengHua LIU YanJu leng JinSong National Key Laboratory of Science and Technology on Advanced Composites in Special Environment Harbin Institute of Technology(HIT)Harbin 150080China Department of Astronautical Science and Mechanics Harbin Institute of Technology(HIT)Harbin 150001China

Shape memory polymers are smart materials that produce shape changes under external stimulus ***-dimensional(4D)printing is a comprehensive technology originate from deformable materials and three-dimensional(3D)printing *** present,4D printed shape memory polymers and shape-changing structures have been applied in various fields,especially in the field of biomedical science.4D printing technology has made a breakthrough of personalized customization in the traditional medical field,providing a new direction for the further development of the biomedical *** this review,the recent research and development of shape memory polymer,3D printing technology,4D printed shape memory polymers and shape-changing structures in biomedical area are *** examples and applications of 4D printed shape memory polymers and their structures in the area of biomedical are also *** on 4D printing,stimulated by different conditions,3D printed objects can be fabricated into various biomedical applications such as cell scaffolds,vascular stents,bone scaffolds,tracheal stents and cardiac stents by different 3D printing ***,the application prospects,existing technical restriction and future development directions of 4D printed shape memory polymers and their structures in the biomedical field are summarized.

关键词： 4D printing shape memory polymers shape-changing structures biomedical applications

Numerical and Experimental Investigation of High-efficiency Axial-flow Pump

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Chinese Journal of Mechanical Engineering 2010年第1期23卷 38-44页

作者： SHI Weidong ZHANGDesheng GUAN Xingfan leng Hongfei Technology and Research Center of Fluid Machinery Engineering Jiangsu University Zhenjiang 212013 China

The experimental investigation of axial-flow pump has been rapidly developed to meet the needs of South-to-North Water Diversion Project of China. Owing to the boundary conditions of hub, blade tip clearance, much of the physical phenomena and laws involved in this complex flow field can＇t be fully determined. The flow characteristics of the high efficiency axial-flow pump have been simulated by RNG k-e turbulence model and SIMPLEC arithmetic based on FLUENT software. Numerical results indicate that the data from the prediction show agreement with the experimental results, static pressure on pressure side of blades increases slightly at circumferential direction with radius increasing, and keep almost constant at the same radial while increasing gradually from inlet to exit on the suction side along flow direction at design conditions. The static pressure, total pressure and velocity at inlet, impeller outlet and vane outlet were measured by a five-hole probe, and a contrastive experiment was done to investigate the influence of hub leakage. The experimental results show that inlet flow is almost axial and the prerotation is very small at various conditions. The meridional velocity and circulation distribution are almost identical at impeller outlet at design conditions due to steady flow and high efficiency. The residual circulation exits at downstream of the guide vane, and the circumferential velocity component increases linearly from hub to tip at small flow rate conditions. Hub leakage in adjustable blades results in the decrease of the meridional velocity and circulation at blade exit near hub. The results of numerical simulation and experiments supply important flow structure information for the high-efficiency axial-flow pump.

关键词： axial-flow pump flow field multi-conditions high efficiency probe hub leakage

Support Vector Machine active learning for 3D model retrieval

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1953-1961页

作者： leng Biao QIN Zheng LI Li-qun Department of Computer Science and Technology Tsinghua University Beijing 100084 China School of Software Tsinghua University Beijing 100084 China

In this paper, we present a novel Support Vector Machine active learning algorithm for effective 3D model retrieval using the concept of relevance feedback. The proposed method learns from the most informative objects which are marked by the user, and then creates a boundary separating the relevant models from irrelevant ones. what it needs is only a small number of 3D models labelled by the user. It can grasp the user＇s semantic knowledge rapidly and accurately. Experimental results showed that the proposed algorithm significantly improves the retrieval effectiveness. Compared with four state-of-the-art query refinement schemes for 3D model retrieval, it provides superior retrieval performance after no more than two rounds of relevance feedback.

关键词： 3D model retrieval Shape descriptor Relevance feedback Support Vector Machine (SVM) Active learning

Mean width inequalities for symmetric Wulff shapes

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Science China Mathematics 2014年第8期57卷 1649-1656页

作者： GUO LuJun leng GangSong College of Mathematics and Information Science Henan Normal University Department of Mathematics Shanghai University

We establish the mean width inequalities for symmetric Wulff shapes by a direct *** also yield the dual inequality along with the equality *** new inequalities have Barthe’s mean width inequalities for even isotropic... 详细信息

关键词： isotropic measure Wulff shape mean width Ball-Barthe inequalities

Stability Control Method for Hybrid AC-DC Transmission Systems Considering Cross-region Multi-energy Coordination

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 753-760页

作者： Peng Sun Yun Teng Ouyang leng Zhe Chen Shenyang University of Technology Shenyang 110870China State Grid East Inner Mongolia Economic Research Institute Huhhot 010020China Department of Energy Technology Aalborg UniversityAalborgDenmark

China has built the largest hybrid AC-DC power systems with the highest voltage levels in the *** to effectively guarantee the stable operation of the hybrid AC-DC power systems is a critical undertaking and technical *** view of the stability problems of hybrid AC-DC transmission systems with a high percentage of wind power,a hybrid AC・DC transmission system's stability control method that considers cross-region multi-energy coordination is established in this *** at the uncertainty of a high percentage of wind power,the dynamic inversion method is used as the inner loop for robust control,and the battery energy storage and regenerative electric boiler are used as multiple energy sources to coordinate,and the outer loop robust control is used for uncertainty *** hybrid AC-DC weak-sending terminal system with wind power is analyzed and designed by//-synthesis based on the Hg control,and a stability control method for hybrid AC-DC transmission systems,considering cross-region multi-energy coordination,is *** results show that the model proposed in this paper can guarantee the robustness of the dynamic inversion method and improves the control performance of AC-DC transmission systems.

关键词： AC-DC transmission system multi-energy coordination robust control uncertainty

Electronic and Optical Properties of B- and/or In-Doped GaAs Calculated Using Many-body Green＇s Function Theory

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Chemical Research in Chinese Universities 2016年第6期32卷 996-1004页

作者： LIANG Dongmei leng Xia MA Yuchen School of Chemistry and Chemical Engineering Shandong University Jinan 250100 P. R. China College of Physics and Electronic Engineering Kaili University Kaili 556011 P. R. China

Using ab initio many-body Green＇s Function theory, the electronic and optical properties of pure BAs,InAs as well as B- and/or In-doped GaAs supercells were studied. The results show that the calculated quasiparticleband gaps of BAs and InAs are in agreement with the experiments. The electronic and optical absorption properties of B-and/or In-doped GaAs are very sensitive to the lattice constant models used in the calculations, which can explainthe controversies in previous theoretical and experimental works. Under the lattice constant condition based on theVegard＇s Law, the reduced band gap and the redshift of the first excited state E0 can be observed for InyGa1-y As withIn concentrations（atomic fractions） ranging from 0 to 15.625%, while the band gap increase and the blueshift of stateE0 can be realized for BxGal-xAs. However, an opposite trend can be found when the lattice constant is fixed to theexperimental value, i.e., In doping leads to a band gap increase and a blueshift of the E0 state, while B doping resultsin a band gap decrease and a redshift of the E0 state. For BxGal-x-y InyAs, the values of the band gap variation and theshift of state E0 are well located between the B and In mono-doping cases. It is worth mentioning that B doping doesnot introduce new impurity states in the band gap of GaAs or InyGa1-2As.

关键词： GaAs Doping Electronic structure Optical property First principles calculation