检索结果-南通市图书馆

Delaunay graph-based moving mesh method with damping functions

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2018年第11期31卷 2093-2103页

作者： Yibin WANG ning QIN ning zhao College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Department of Mechanical Engineering The University of Sheffield

The fluid–structure interaction and aerodynamic shape optimization usually involve the moving or deforming boundaries, thus the dynamic mesh techniques are the key techniques to cope with such deformation. A novel dynamic mesh method was developed based on the Delaunay graph in this paper. According to the Delaunay graph, the mesh points were divided into groups. In each group, a factor ranging from 0 to 1 was calculated based on the area/volume ratio. By introducing a proper function for this factor, this method can control the mesh quality with high efficiency. Several test cases were compared with other dynamic mesh methods regarding mesh quality and CPU time, such as radial basis function method and Delaunay graph mapping method.

关键词： Delaunay graph mapping Dynamic mesh Grid deformation Mesh Moving mesh

A robust algorithm for moving interface of multi-material fluids based on Riemann solutions

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2006年第6期22卷 509-519页

作者： Xueying Zhang ning zhao College of Science Hohai University Nanjing 210098 China College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In the paper, the numerical simulation of interface problems for multiple material fluids is studied. The level set function is designed to capture the location of the material interface. For multi-dimensional and multi-material fluids, the modified ghost fluid method needs a Riemann solution to renew the variable states near the interface. Here we present a new convenient and effective algorithm for solving the Riemann problem in the normal direction. The extrapolated variables are populated by Taylor series expansions in the direction. The anti-diffusive high order WENO difference scheme with the limiter is adopted for the numerical simulation. Finally we implement a series of numerical experiments of multi-material flows. The obtained results are satisfying, compared to those by other methods.

关键词： Multi-material fluids Ghost fluidmethod Riemann problem Level set method WENO scheme

ON ENTROPY CONDITIONS OF HIGH RESOLUTION SCHEMES FOR SCALAR CONSERVATION LAWS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2001年第4期19卷 371-384页

作者： ning zhao Hua-mu Wu Department of Aerodynamics Nanjing University of Aeronautics and AstronauticsNanjing 210016China LSEC ICMSECAcademy of Mathematics and Systems SciencesChinese Acaderny of SciencesBeijing 100080China

Presents a method of proof which improves the estimates of entropy production for general total variation diminishing (TVD) schemes. Elements of the general theory of TVD schemes; Basis for obtaining the entropy inequality of a class of second order resolution-TVD schemes for strict convex conservation laws; Definition of discrete entropy inequality.

关键词： entropy condition high resolution schemes conservation laws

Digital Twin Technology of Human-Machine Integration in Cross-Belt Sorting System

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第2期37卷 195-212页

作者： Yanbo Qu ning zhao Haojue Zhang School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China Institute of Microelectronics of the Chinese Academy of Sciences Beijing 100029China Wayzim Technology Co. LtdWuxi 214108China Business School Beijing Technology and Business UniversityBeijing 100048China

The Chinese express delivery industry processes nearly 110 billion items in 2022,averaging an annual growth rate of 200%.Among the various types of sorting systems used for handling express items,cross-belt sorting systems stand out as the most ***,despite their high degree of automation,the workload for operators has intensified owing to the surging volume of express *** the era of Industry 5.0,it is imperative to adopt new technologies that not only enhance worker welfare but also improve the efficiency of cross-belt *** a balance between efficiency in handling express items and operator well-being is *** twin technology offers a promising solution in this respect.A realization method of a human-machine integrated digital twin is proposed in this study,enabling the interaction of biological human bodies,virtual human bodies,virtual equipment,and logistics equipment in a closed loop,thus setting an operating *** technologies in the proposed framework include a collection of heterogeneous data from multiple sources,construction of the relationship between operator fatigue and operation efficiency based on physiological measurements,virtual model construction,and an online optimization module based on real-time *** feasibility of the proposed method was verified in an express distribution center.

关键词： Industry 5.0 Cross-belt sorting system Human-machine integrated Digital twin Online optimization

Remarkably reducing carbon loss and H2 consumption on Ni–Ga intermetallic compounds in deoxygenation of methyl esters to hydrocarbons

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2020年第2期29卷 194-208页

作者： ning zhao Ying Zheng Jixiang Chen Tianjin Key Laboratory of Applied Catalysis Science and Technology Department of Catalysis Science and EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China

Ni–Ga alloy(Ni/Ga atomic ratio of 8),Ni3Ga and Ni5Ga3 intermetallic compounds(IMCs)catalysts were prepared from Ni–Mg-Al-Ga layered double hydroxides(LDHs)for the deoxygenation of methyl esters to *** the alloy and IMCs,the presence of Ga reduced the surface Ni atom density,and the charge transfer from Ga to Ni increased the electron density of *** the deoxygenation of methyl laurate,the Ni catalyst gave a complete hydrogenolysis of methyl laurate to CH4at 330°C and 3.0 MPa,while the presence of Ga promoted the HDO pathway and suppressed C–C bond hydrogenolysis and *** Ni5Ga3 catalyst exhibited the best desired *** at 400°C,it gave the yield of C11 and C12 hydrocarbons of ~99%,and the selectivity to CH4(SCH4) was only 2.4%.In the deoxygenation of methyl octanoate and methyl palmitate,the Ni5Ga3 catalyst also gave the yield of hydrocarbons above95%.Reactivity evaluation and methyl propionate-TPD and TPSR results indicate that the C–OCH3 bond instead of the O–CH3 one was cleaved on both Ni and bimetallic Ni–Ga *** is highlighted that methanol,derived from the C–OCH3 bond hydrogenolysis,mainly decomposed to CO and H2 on IMCs,while it was converted to methane on metallic Ni and *** is of great significance that H2 could be yielded from the methyl ester *** short,the utilization of Ni–Ga IMCs can effectively reduce carbon loss and H2 consumption,all of which are ascribed to the geometric and electronic effects of Ga.

关键词： Ni–Ga intermetallic compounds Methyl ester Decarbonylation/decarboxylation Hydrodeoxygenation C–C bond hydrogenolysis Methanation

Hybrid Cartesian Grid Method for Moving Boundary Problems

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2016年第1期33卷 37-44页

作者： Shen Zhiwei zhao ning College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems. The near body region is discretized by using the body-fitted structured grids, while the remaining computational domain is tessellated with the generated Cartesian grids. As the body moves, the structured grids move with the body and the outer boundaries of inside grids are used to generate new holes in the outside adaptive Cartesian grid to facilitate data communication. By using the alternating digital tree （ADT） algorithm, the computational time of hole-cutting and identification of donor cells can be reduced significantly. A compressible solver for unsteady flow problems is developed. A cell-centered, second-order accurate finite volume method is employed in spatial discreti- zation and an implicit dual-time stepping low-upper symmetric Gauss-Seidei （LU-SGS） approach is employed in temporal discretization. Geometry-based adaptation is used during unsteady simulation time steps when boundary moves and the flow solution is interpolated from the old Cartesian grids to the new one with inverse distance weigh- ting interpolation formula. Both laminar and turbulent unsteady cases are tested to demonstrate the accuracy and efficiency of the proposed method. Then, a 2-D store separation problem is simulated. The result shows that the hybrid Cartesian grid method can handle the unsteady flow problems involving large-scale moving boundaries.

关键词： hybrid Cartesian grid l moving boundary alternating digital tree (ADT) algorithm unsteady flow

Emergency Local Searching Approach for Job Shop Scheduling

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2013年第5期26卷 918-927页

作者： zhao ning CHEN Siyu DU Yanhua School of Mechanical Engineering University of Science and Technology Beijing

Existing methods of local search mostly focus on how to reach optimal ***,in some emergency situations,search time is the hard constraint for job shop scheduling problem while optimal solution is not *** this situation,the existing method of local search is not fast *** paper presents an emergency local search(ELS) approach which can reach feasible and nearly optimal solution in limited search *** ELS approach is desirable for the aforementioned emergency situations where search time is limited and a nearly optimal solution is sufficient,which consists of three ***,in order to reach a feasible and nearly optimal solution,infeasible solutions are repaired and a repair technique named group repair is ***,in order to save time,the amount of local search moves need to be reduced and this is achieved by a quickly search method named critical path search(CPS).Finally,CPS sometimes stops at a solution far from the optimal *** order to jump out the search dilemma of CPS,a jump technique based on critical part is used to improve ***,the schedule system based on ELS has been developed and experiments based on this system completed on the computer of Intel Pentium(R) 2.93 *** experimental result shows that the optimal solutions of small scale instances are reached in 2 s,and the nearly optimal solutions of large scale instances are reached in 4 *** proposed ELS approach can stably reach nearly optimal solutions with manageable search time,and can be applied on some emergency situations.

关键词： emergency local search job shop scheduling problem schedule critical path critical constraint part

Adaptive cancellation of Es layer interference using auxiliary horizontal antennas

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2006年第2期17卷 313-315页

作者： zhao Long Zhang ning Inst. of Electronic Engineering Harbin Inst. of Technology Harbin 150001 P. R. China

Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.

关键词： dual-polarization auxiliary horizontal antennas adaptive cancellation signal-to-interference ratio.

Solar Flux Measuring and Optical Efficiency Forecasting of the Linear Fresnel Reflector Concentrator after Dust Accumulation

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2022年第3期31卷 663-677页

作者： zhao Xiaoyan YAN Suying ZHANG Na zhao ning GAO Hongwei College of Energy and Power Engineering Inner Mongolia University of TechnologyHohhot010051China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China

The linear Fresnel reflector concentrator(LFRC)is widely used in the field of solar energy utilization due to its simple structure,low cost,and excellent wind ***,the LFRC operates outdoors all year round,and the dust accumulation on the mirror will reduce the optical efficiency of the system,so it needs to be perfected and *** this paper,a focal plane energy flux experimental device was designed to test the energy flux of the system under different dust accumulation *** results indicate that,the dust density on the mirror increased and the energy flux on the focal plane decreased with increase of dust accumulation *** undergoing dust accumulation for 35 days,the dust density on the mirror reached 4.33 g/m^(2)and the average energy flux on the focal plane decreased to 1.78 kW/m^(2).Additionally,the variation of reflectivity caused by dust accumulation on mirror was taken as the quantitative index,and a prediction model for the impact of dust on the optical efficiency of the system was *** results will provide guidance for improving the optical efficiency of the LFRC.

关键词： dust accumulation energy flux linear Fresnel reflector concentrator optical efficiency forecast