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COMPUTATION OF TURBULENT FLOWS WITH COMPLEX BOUNDARIES

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Journal of Hydrodynamics 1991年第2期3卷 99-106页

作者： Fu, Song zhang, Zhao-shun Liu, Guo-hua Tsinghua Univ Beijing China

Numerical simulations of steady, incompressible turbulent flows with complex boundaries are presented in this article. The complex boundary geometries are accurately represented via a boundary-fitted orthogonal coordinate system generated by the solution of a set of elliptic partial-differential equations (PDEs). Thus, an irregular physical space can be mapped into a rectangular computational domain. The Turbulent flow is described by time-averaging technique in which the κ-Ε two-equation-type Boussinesq-viscosity model (BVM) is employed to represent the resulting turbulence quantities, Reynolds stresses u,uj¯. Numerical solution is then obtained by solving the transport equations in their physical-component forms derived through the coordinate transformation from Cartesian coordinates to the orthogonal ones. Solution algorithm employs finite-volume method, with SIMPLE procedure to determine pressure field. The combined procedures are tested in a single-sided sudden-expansion flow situation. Computational results show favourable agreement with experiment data, indicating that curvilinear-orthogonal coordinate system can be incorporated into turbulent flow computations. A further computation of a pipe flow with rapidly converging/diverging wall provides confirming results.

关键词： Mathematical Techniques Geometry Viscosity

Design and experimental study of the control system for precision seed-metering device

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International Journal of Agricultural and Biological Engineering 2014年第3期7卷 13-18页

作者： Zhai Jianbo Xia Junfang Zhou Yong zhang shun College of Engineering Huazhong Agricultural UniversityWuhan430070HubeiProvinceChina

The precision seeding technique has been developed at full speed along with the continuous development of new agricultural technologies,especially those concerning cultivated *** seed-metering device is the key component of a precision seeder.A ground wheel is used to drive the seed-metering device of the conventional direct ***,the wheel bears high resistance and easily ***,the adjustment of the precision seeder’s seeding rate is more *** order to solve these problems,a control system which could keep the rotational speed of the seed-metering device consistent with the seeder’s working speed for the precision seed-metering device was *** control system includes a Hall sensor,a single chip microcomputer system,a motor control module,a stepper motor and a *** control system used a Hall sensor to measure the seeder’s working speed and employed a single chip microcomputer system to predict the rotational speed of seed-metering *** would then determine the relationship between the seeder’s working speed and the rotational speed of the seed metering-device according to the seeder’s working state,distance between seeds and the requirement of sowing *** system could effectively reduce the influence of inhomogeneous sowing caused by the ground wheel’s *** system was found to be reliable by the *** seeding control system could also make the speed of the seed-metering device and seeder’s uniform,improving the uniformity of the amount of seeding,and achieving the goal of *** new design provides a platform to solve problems of the seed-metering device and the seeder.

关键词： agricultural machinery precision seeder seed-metering device sensor control system stepper motor

Optimal Power Allocation for Multiuser OFDM-Based Cognitive Heterogeneous Networks

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China Communications 2017年第9期14卷 52-61页

作者： Yongjun Xu Yuan Hu Qianbin Chen shun zhang Chongqing Key Lab of Mobile Communications Technology Chongqing University of Posts and Telecommunications State Key Laboratory of Integrated Services Networks Xidian University

Heterogeneous network(HetNet) as a promising technology to improve spectrum efficiency and system capacity has been concerned by many scholars, which brings huge challenges for power allocation and interference management in multicell network structures. Although some works have been done for power allocation in heterogeneous femtocell networks, most of them focus centralized schemes for single-cell network under interference constraint of macrocell user. In this paper, a sum-rate maximization based power allocation algorithm is proposed for a downlink cognitive Het Net with one macrocell network and multiple microcell networks. The original power allocation optimization problem with the consideration of cross-tier interference constraint, maximum transmit power constraint of microcell base station and inter-cell interference of microcell networks is converted into a geometric programming problem which can be solved by Lagrange dual method in a distributed way. Simulation results demonstrate the performance and effectiveness of the proposed algorithm by comparing with the equal power allocation scheme.

关键词： cognitive heterogeneous net-works power allocation geometric program-ming lagrange dual method

Aerial Visible-to-Infrared Image Translation:Dataset,Evaluation,and Baseline

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Journal of Remote Sensing

Journal of Remote Sensing 2023年第1期3卷 411-432页

作者： Zonghao Han Ziye zhang shun zhang Ge zhang Shaohui Mei School of Electronics and Information Northwestern Polytechnical UniversityXi’anChina

Aerial visible-to-infrared image translation aims to transfer aerial visible images to their corresponding infrared images,which can effectively generate the infrared images of specific *** some image-to-image translation algorithms have been applied to color-to-thermal natural images and achieved impressive results,they cannot be directly applied to aerial visible-to-infrared image translation due to the substantial differences between natural images and aerial images,including shooting angles,multi-scale targets,and complicated *** order to verify the performance of existing image-to-image translation algorithms on aerial scenes as well as advance the development of aerial visible-to-infrared image translation,an Aerial Visible-to-Infrared Image Dataset(AVIID)is created,which is the first specialized dataset for aerial visible-to-infrared image translation and consists of over 3,000 paired visible-infrared *** the constructed AVIID,a complete evaluation system is presented to evaluate the generated infrared images from 2 aspects:overall appearance and target *** addition,a comprehensive survey of existing image-to-image translation approaches that could be applied to aerial visible-to-infrared image translation is *** then provide a performance analysis of a set of representative methods under our proposed evaluation system on AVIID,which can serve as baseline results for future ***,we summarize some meaningful conclusions,problems of existing methods,and future research directions to advance state-of-the-art algorithms for aerial visible-to-infrared image translation.

关键词： visible Infrared meaningful

Approximate Symmetry Reduction for Initial-value Problems of the Extended KdV-Burgers Equations with Perturbation

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Chinese Physics Letters 2011年第3期28卷 1-4页

作者： LI Ji-Na zhang shun-Li Center for Nonlinear Studies Department of MathematicsNorthwest UniversityXi’an 710069 Center of Nonlinear Science Ningbo UniversityNingbo 315211

Approximate generalized conditional symmetry is developed to study the approximate symmetry reduction for initial-value problems of the extended KdV-Burgers equations with *** equations can be reduced to initial-value problems for some systems of first-order perturbed ordinary differential equations in terms of a new *** classification theorems are obtained and an example is taken to show the main reduction procedure.

关键词： perturbation. value symmetry

Coarsening kinetics and strengthening mechanisms of core-shell nanoscale precipitates in Al-Li-Yb-Er-Sc-Zr alloy

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Journal of Materials Science & Technology 2021年第2期61卷 197-203页

作者： Yang Wang shun zhang Ruizhi Wu Nodir Turakhodjaev Legan Hou Jinghuai zhang Sergey Betsofen Key Laboratory of Superlight Materials&1 Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin 150001China College of Science Heihe UniversityHeihe 164300China Department of Machine Building Tashkent State Technical UniversityTashkent 100056Uzbekistan Moscow Aviation Institute National Research UniversityMoscow 109383Russia

The tailored nanoparticles with a complex core/shell structure can satisfy a variety of demands, such as lattice misfit, shearability and coarsening resistance. In this research, core-shell nanoscale Al3(Yb, Er, Sc,Zr, Li) composite particles were precipitated in Al-2 Li-0.1 Yb-0.1 Er-0.1 Sc-0.1 Zr(wt%) alloy through the double-aging treatment, in which the core was(Yb, Er, Sc, Zr)-rich formed at 300°C and the shell was Li-rich formed at 150°C. The coarsening kinetics and precipitate size distributions(PSDs) of Al3(Yb, Er, Sc,Zr, Li) particles aged at 150°C previously aged at 300°C for 24 h showed a better fit to the relation of 2∝ kt and normal distribution, indicating that the coarsening of precipitates was controlled by interface reaction, not diffusion. The Orowan bypass strengthening was operative mechanism at 150°C.

关键词： Al-Li alloys Aging Core-shell structure Coarsening kinetics Strengthening mechanisms

Influence of induced ciprofloxacin resistance on efflux pump activity of Klebsiella pneumoniae

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第9期14卷 837-843页

作者： Hai-qin ZHONG shun zhang Hong PAN Ting CAI Department of Internal Medicine School of MedicineNingbo University Stem Cell Laboratory Ningbo No.2 Hospital Clinical Laboratory Ningbo No.2 Hospital Emergency Department Ningbo No.2 Hospital

Objective:The efflux pump(EP) is one of the major mechanisms of antibiotic resistance in Klebsiella ***,there are few reports on the effect of the abuse of antibiotic use on the activity of *** determine whether the use of low efficacy antibiotics has any effect on the activity of EPs and induces drug resistance in ***,we investigated the effect of ciprofloxacin on the activity of EPs in *** ***:Sixteen susceptible *** strains were isolated from patients and their minimum inhibitory concentrations(MICs) of ciprofloxacin were measured in the absence and presence of the pump inhibitor carbonyl cyanide m-chlorophenyl hydrazone(CCCP).The strains were then induced with a gradient of ciprofloxacin until the MICs of the strains showed no further increase,to obtain induced resistant *** EP activities of the strains before and after induction were compared using EP inhibition and ethidium bromide(EtBr) accumulation ***:The MIC values of the strains were 16 256 times higher after induction than before *** the presence of CCCP,the MIC values of 50% of the induced strains were 2 4-fold lower than that in the absence of this *** EtBr accumulation assay showed that the fluorescence of EtBr in the induced cells was lower than that in the cells before ***:EPs are widespread in susceptible and drug-resistant *** *** with ciprofloxacin may increase the activity of EPs in *** EtBr accumulation assay is more sensitive than the EP inhibition assay in evaluating the activity of EPs in ***.

关键词： Klebsiella pneumoniae Efflux pump Ciprofloxacin Antibiotic resistance

Invariant Sets and Exact Solutions to Higher-Dimensional Wave Equations

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Communications in Theoretical Physics 2008年第5期49卷 1119-1124页

作者： QU Gai-Zhu zhang shun-Li ZHU Chun-Rong Center for Nonlinear Studies Department of Mathematics Northwest University Xi＇an 710069 China Center of Nonlinear Science Ningbo University Ningbo 315211 China Department of Mathematics Anhui Normal University Wuhu 241000 China

The invariant sets and exact solutions of the （1 ＋ 2）-dimensional wave equations are discussed. It is shown that there exist a class of solutions to the equations which belong to the invariant set E0 = {u ： ux = ... 详细信息

关键词： wave equation invariant set exact solution

Symmetry Breaking for Black-Scholes Equations

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Communications in Theoretical Physics 2007年第6期47卷 995-1000页

作者： YANG Xuan-Liu zhang shun-Li QU Chang-Zheng School of Economics and Management Tsinghua University Beijing 100084 China Center for Nonlinear Studies Northwest University Xi＇an 710069 China Department of Mathematics Northwest University Xi＇an 710069 China

Black-Scholes equation is used to model stock option pricing. In this paper, optimal systems with one to four parameters of Lie point symmetries for Black-Scholes equation and its extension are obtained. Their symmetry breaking interaction associated with the optimal systems is also studied. As a. result, symmetry reductions and corresponding solutions for the resulting equations are obtained.

关键词： Black-Scholes equation symmetry optimal system symmetry breaking solution