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A Numerical Modeling of the Vortex-induced Vibration of Cascade in Turbomachinery using Immersed Boundary Method

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Journal of Thermal Science 2011年第3期20卷 229-237页

作者： Guotun Hu lin du Guohua Zhong Xiaofeng Sun School of Jet Propulsion Beihang University Beijing 100191 China

Based on the immersed boundary method,a fast simulation for solving unsteady,incompressible,viscous flow associated with the oscillating cascade is established on a quasi-three-dimensional coordinate *** numerical method is applied to the simulation of the flow passing an oscillating circular cylinder which is forced to move in X direction under prescribed motions in water at rest at low Keulegan-Carpenter *** vor-tex-induced vibration of a cylinder with two degrees of freedom which oscillates in in-line direction and transverse direction is simulated using this *** results are in good agreement with the previous *** the method is extended to the oscillating cascade simulation of making various *** is found that the IBPA(inter blade phase angle) will change as the time goes on,because of the non-uniformity of the flow in the circumferential direction,until the oscillating cascade goes to a stable *** reduced velocity and the number of blades are chosen to investigate the effects of them on *** results indicate that both the reduced velocity and the number of blades are the main factors which influence *** is worth noting that the coupling process is not necessary to generate any body-fitting grids,which makes it much faster in computational process for such a complicated fluid-structure interaction problem.

关键词： turbomachinery IB method vortex-induced vibration oscillating cascade

Effect of ytterbium on sodium current and its kinetics in rat hippocampal neurons

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Chinese Science Bulletin 2014年第7期59卷 625-629页

作者： Zhengqing du Kun Tian Department of Environmental Economics Shanxi University of Finance and Economics

This study addressed the effects of Yb3+ on voltage-gated sodium currents in rat hippocampal neurons using the whole-cell patch-clamp technique. Voltage-clamp recordings in single neurons were filtered and stored in a computer. Yb3+ increased the amplitude of sodium currents in a concentration-dependent and voltage-dependent manner. The 50 % enhancement concentration of Yb3+ on sodium currents was about 8.97 lmol/L, which was different from the inhibitory effects of Yb3+ on potassium current. The analysis on the activation and inactivation kinetics of Na+ current showed that 100 lmol/L Yb3+ did not change the process of activation and inactivation. In addition, the times reaching the peak of current(t) and inactivated time constant(s) were voltage dependent. 100 lmol/L Yb3+ significantly prolonged the time to peak at-70 and-80 mV. The effect disappeared at the positive direction of-70 mV. Furthermore, Yb3+ decreased s values to more positive values than-80 mV. In total, Yb3+ did not change the process of activation, but impelled inactivated process. Yb3+ mainly increased the Na+ current through changing its conductance. It might be one of the mechanisms that Yb3+ affected the hippocampal neurons.

关键词：海马神经元失活动力学钠电流大鼠全细胞膜片钳技术镱电压依赖性浓度依赖性

Vibration Characteristics and Power Transmission of Coupled Rectangular Plates with Elastic Coupling Edge and Boundary Restraints

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Chinese Journal of Mechanical Engineering 2012年第2期25卷 262-276页

作者： CHEN Yuehua JIN Guoyong du Jingtao liU Zhigang College of Power and Energy Engineering Harbin Engineering UniversityHarbin 150001China

Coupled-plate structures are widely used in the practical engineering such as aeronautical,civil and naval engineering *** works can be found on the vibration of the coupled-plate structure due to the increased mathematical complexity compared with the single plate *** order to study analytically the vibration characteristics and power transmission of the coupled-plate structure,an analytical model consisting of three coupled plates elastically restrained along boundary edges and elastically coupled with arbitrary angle is considered,in which four groups of springs are distributed consistently along each edge of the model to simulate the transverse shearing forces,bending moments,in-plane longitudinal forces and in-plane shearing forces *** elastic coupling condition and general boundary condition of both flexural and in-plane vibrations taken into account by setting the stiffness of corresponding springs,the double Fourier series solution to the dynamic response of the structure was obtained by employing the Rayleigh-Ritz *** order to validate the model,the natural frequency and velocity response of the model are firstly checked against results published in literatures and the ANSYS data,and good agreement was ***,numerical simulation of the effects of several relevant parameters on the vibration characteristics and power transmission of the coupled structure were performed,including boundary conditions,coupling conditions,coupling angle,and location of the external *** and energy transmission behaviors were analyzed *** results show that the power transmission can be significantly influenced by the boundary restraints and the location of *** the excitation is located at the central symmetry point of the model,the energy flow shows a symmetrical *** the location deviates from the central symmetry point,the power circumfluence occurs and the vortex energy field is formed

关键词： vibration power transmission coupled-plate structure elastic restraints

Numerical Simulation on the Effect of Tip Clearance Size on Unsteadiness in Tip Clearance Flow

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Journal of Thermal Science 2008年第4期17卷 337-342页

作者： Juan du Feng lin Hongwu Zhang Jingyi Chen Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China Key Laboratory of Advanced Energy and Power Chinese Academy of Sciences （Institute of Engineering Thermophysics） Beijing 100190 China Graduate School of Chinese Academy of Sciences Beijing 100190 China

Unsteadiness of tip clearance flow with three different tip clearance sizes is numerically investigated in this paper. NASA Rotor 67 is chosen as the computational model. It is found that among all the simulated cases, the un- steadiness exists when the size of the tip clearance is equal to or larger than design tip clearance size. The relative total pressure coefficient contours indicate that region of influence by tip leakage flow augments with the increase of tip clearance size at a fixed mass flow rate. Root Mean Square contours of static pressure distribution in the rotor tip region are provided to illustrate that for design tip clearance （1.1% tip chord） the strongest fluctuating region is located on pressure side of blade near leading edge, while for the larger tip clearance （2.2% tip chord）, it is in the region of the interaction between the shock wave and the tip leakage flow.

关键词： tip clearance flow tip leakage flow unsteadiness transonic rotor

Polar-coded forward error correction for MLC NAND flash memory

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Science China(Information Sciences) 2018年第10期61卷 224-239页

作者： Haochuan SONG Jen-Chien FU Shih-Jia ZENG Jin sha Zaichen ZHANG Xiaohu YOU Chuan ZHANG Lab of Efficient Architectures for Digital-communication(LEADS) National Mobile Communications Research Laboratory Southeast University Quantum Information Center of Southeast University National Mobile Communications Research Laboratory Southeast University lite-On Technology Corporation School of Electronic Science and Engineering Nanjing University

With the ever-growing storage density, high-speed, and low-cost data access, flash memory has inevitably become popular. Multi-level cell(MLC) NAND flash memory, which can well balance the data density and memory stability, has occupied the largest market share of flash memory. With the aggressive memory scaling, however, the reliability decays sharply owing to multiple interferences. Therefore, the control system should be embedded with a suitable error correction code(ECC) to guarantee the data integrity and accuracy. We proposed the pre-check scheme which is a multi-strategy polar code scheme to strike a balance between reasonable frame error rate(FER) and decoding latency. Three decoders namely binaryinput, quantized-soft, and pure-soft decoders are embedded in this scheme. Since the calculation of soft loglikelihood ratio(LLR) inputs needs multiple sensing operations and optional quantization boundaries, a 2-bit quantized hard-decision decoder is proposed to outperform the hard-decoded LDPC bit-flipping decoder with fewer sensing operations. We notice that polar codes have much lower computational complexity compared with LDPC codes. The stepwise maximum mutual information(SMMI) scheme is also proposed to obtain overlapped boundaries without exhausting search. The mapping scheme using Gray code is employed and proved to achieve better raw error performance compared with other alternatives. Hardware architectures are also given in this paper.

关键词： polar coding non-volatile memory error correcting code NAND flash memory

Ratiometric recognition of humidity by a europium-organic framework equipped with quasi-open metal site

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Science China Chemistry 2021年第10期64卷 1723-1729页

作者： Wei Zhang Jian Xie Zhuyin Sui Zhijun Xu Xiaoze Wang Min Lei Hongfa Zhang Zhongyue li Yanlong Wang Wei liu Wei du Shuao Wang School of Environmental and Material Engineering Yantai UniversityYantai 264005China State Key Laboratory of Radiation Medicine and Protection School for Radiological and Interdisciplinary Sciences(RAD-X)Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education InstitutionsSoochow UniversitySuzhou 215123China

Open metal site(OMS)seated in a luminescent lanthanide(Ln)metal center offers an opportunity for rationally tuning the spectroscopic behavior of lanthanide-organic frameworks aiming for a wide range of sensing ***,given the spherical nature of common coordination geometries of trivalent lanthanides and the generally strong Ln–O bonds,the lanthanide based OMS is rarely reported and difficult to be *** report here a unique europium-organic framework containing abundant quasi-OMS that is protected by an abnormal weak Eu–O *** quasi-OMSs offer reversible direct binding sites for water molecules probed by X-ray crystallography,leading to sensitive,visible,and ratiometric luminescent sensing toward humidity and water content in organic *** specific recognition of water based on quasi-luminescentOMSs gives rise to a superior water detection limit down to 0.0003%v/v,which is one order of magnitude lower than that of Karl Fischer method.

关键词： metal-organic framework luminescence detection

Cloud Det ection Using Super Pixel Classification and Semantic Segmentation

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Journal of Computer Science & Technology 2019年第3期34卷 622-633页

作者： Han liu Hang du Dan Zeng Qi Tian Key Laboratorij of Specialty Fiber Optics and Optical Access Networks Shanghai UniversityShanghai 200444China shanghai Institute of Advanced Communication and Data Science Shanghai UniversityShanghai 200444China Department of Computer Science The University of Texas at San AntonioSan AntonioU.S.A.

Cloud detection plays a very significant role in remote sensing image *** paper introduces a cloud detection method based on super pixel level classification and semantic ***,remote sensing images are segmented into super *** super pixels compose a super pixel level remote sensing image *** cloud detection is essentially a binary classification task,our database is labeled into four categories to improve the generalization ability:thick cloud,cirrus cloud,building,and other ***,the super pixel level database is used to train our cloud detection models based on convolution neural network(CNN)and deep *** fusion CNN is proposed considering super pixel level images contain less semantic information than normal *** full advantage of low-level features like color and texture information,it is more applicable for super pixel level ***,a distance metric is proposed to refine ambiguous super ***,an end-to-end cloud detection model based on semantic segmentation is *** model has no restrictions on the input size,and takes less *** results show that compared with other cloud detection *** proj)osed method acliieves better performance.

关键词： cloud detection convolution neural network deep forest semantic segmentation

Constructing S-scheme charge separation in cobalt phthalocyanine/oxygen-doped g-C_(3)N_(4) heterojunction with enhanced photothermal-assisted photocatalytic H_(2) evolution

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Rare Metals 2024年第1期43卷 198-211页

作者： Wei-Long Shi Zheng Xu Yu-Xing Shi ling-ling li Jia-lin Lu Xin-Hai Sun Xin du Feng Guo Chang-Yu Lu School of Material Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China School of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina College of Chemistry Zhengzhou UniversityZhengzhou 450001China School of Water Resource and Environment Hebei Province Key Laboratory of Sustained Utilization and Development of Water RecourseHebei Center for Ecological and Environmental Geology ResearchHebei Geo UniversityShijiazhuang 050031China

Hydrogen acquisition from solar energy is an effective way to address energy crisis,which makes the development of efficient photocatalysts become the main direction of scientific ***,cobalt phthalocyanine/oxygen-doped g-C_(3)N_(4)(CoPc/OCN) S-scheme heterojunction photocatalyst was designed by coupling multi-step calcination with solvothermal method for enhanced photothermal-assisted photocatalytic H_(2) *** multistep calcined g-C_(3)N_(4) is easier for O-doping formation,and the ethanol solvothermal strategy is utilized to enhance the dispersion of CoPc on OCN nano sheet surface and forms sufficient S-scheme heterojunction through *** addition,the active sites and excellent photothermal properties of CoPc itself further improve the integrated photocatalytic activity of CoPc/OCN S-scheme *** optimal photocatalytic hydrogen evolution rate of CoPc/OCN S-scheme heterojunction photocatalyst reached 9.56 mmol·g^(-1)·h^(-1),which is 2.69 and 1.23 times higher than that of CN and OCN,*** work provides a valuable design idea and scheme for enhancing the multi-factor co-assisted photocatalytic H_(2) evolution performance.

关键词： Photothermal Photocatalytic H_(2)evolution Cobalt phthalocyanine Oxygen-doped g-C_(3)N_(4) Sscheme heterojunction

Star-factorization of the Complete Bipartite Multigraphs

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Acta Mathematicae Applicatae Sinica 2023年第2期39卷 239-248页

作者： Jing SHI Jian WANG Bei-liang du School of Science Nantong UniversityNantong 226007China Department of Mathematics Suzhou UniversitySuzhou 215006China Mathematics Teaching and Research Office Nantong Vocational CollegeNantong 226007China

LetλK_(m,n)be a complete bipartite multigraph with two partite sets having m and n vertices,respectively.A K_(p,q)-factorization ofλK_(m,n)is a set of K_(p,q)-factors ofλK_(m,n)which partition the set of edges ofλK_(m,n).Whenλ=1,Martin,in[Complete bipartite factorizations by complete bipartite graphs,Discrete Math.,167/168(1997),461–480],gave simple necessary conditions for such a factorization to exist,and conjectured those conditions are always *** this paper,we will study the K_(p,q)-factorization ofλK_(m,n)for p=1,to show that the necessary conditions for such a factorization are always sufficient whenever related parameters are sufficiently large.

关键词： complete bipartite multigraph star factorization