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A MODEL AND AN ANALYTICAL METHOD FOR CONVEYOR SYSTEMS IN DISTRIBUTION CENTERS

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Journal of Systems Science and Systems Engineering 2010年第4期19卷 408-429页

作者： Ying WANG chen zhou Manheim Consulting USA Stewart School of Industrial and Systems Engineering Georgia Institute of Technology USA

The design and operation of high volume conveyor systems in distribution centers are important due to its high cost, large footprint and critical role in the system. However, there is no analytical model available. In this paper, we study the characteristics of the conveyor sortation system, develop a generic model of a complex conveyor network. We then use the Delay and Stock abstraction to develop an approximate analytical method using sample path analysis and dynamic network flow model. The decision variables include length of accumulation segments and the speeds of conveyor components aforementioned decision variables. This analytical solution provides faster analysis, insights and useful subgradient with respect to the decision variables.

关键词： Conveyor system sortation system network accumulation sample path analysis dynamic network flow

Model for the static friction coefficient in a full stick elastic-plastic coated spherical contact

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Friction 2019年第6期7卷 613-624页

作者： zhou chen Izhak ETSION Department of Mechanical Engineering Technion

Finite element analysis is used to investigate an elastic-plastic coated spherical contact in full stick contact condition under combined normal and tangential loading. Sliding inception is associated with a loss of tangential stiffness. The effect of coating thickness on the static friction coefficient is intensively investigated for the case of hard coatings. For this case, with the increase in coating thickness, the static friction coefficient first increases to its maximum value at a certain coating thickness, thereafter decreases, and eventually levels off. The effect of the normal load and material properties on this behavior is discussed. Finally, a model for the static friction coefficient as a function of the coating thickness is provided for a wide range of material properties and normal loading.

关键词： contact mechanics elastic‐plastic contact spherical contact static friction hard coatings

Multidisciplinary design optimization of adaptive wing leading edge

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Science China(Technological Sciences) 2013年第7期56卷 1790-1797页

作者： SUN RuJie chen GuoPing zhou chen zhou LanWei JIANG JinHui State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics

Adaptive wing can significantly enhance aircraft aerodynamic performance, which refers to aerodynamic and structural opti-mization designs. This paper introduces a two-step approach to solve the interrelated problems of the adaptive leading edge. In the first step, the procedure of airfoil optimization is carried out with an initial configuration of NACA 0006. On the basis of the combination of design of experiment (DOE), response surface method (RSM) and genetic algorithm (GA), an adaptive air-foil can be obtained whose lift-to-drag ratio is larger than the baseline airfoil's at the given angle of attack and subsonic *** next step is to design a compliant structure to achieve the target airfoil shape, which is the optimization result of the previous step. In order to minimize the deviation of the deformed shape from the target shape, the load path representation topology method is presented. This method is developed by way of GA, with size and shape optimization incorporated in it simul-taneously. Finally, a comparison study with the Solid Isotropic Material with Penalization (SIMP) method in Altair OptiStruct is conducted, and the results demonstrate the validity and effectiveness of the proposed approach.

关键词： adaptive wing multidisciplinary design optimization aerodynamic optimization structural optimization genetic algorithm

Inversion of near-field waveform data for earthquake source rupture process(Ⅱ):Inversion of Chi Chi earthquake source,20 September,1999,Taiwan

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Science China Earth Sciences 2006年第3期49卷 272-282页

作者： zhou Shiyong chen Xiaofei Department of Geophysics Peking University Beijing 100871 China Department of Geophysics Peking University Beijing 100871 China

The new inversion algorithm developed based on the recent progress in thenonlinear programming study by us is used to invert the earthquake source process of Chi Chiearthquake M_w7.6, 20 Semptember,1999, Taiwan. A curve fault model is constructed in our inversionto make the fault model close to the real rupturing fault to reduce the influence from thediscrepancy between the constructed fault model and the real rupturing fault. The results show that(1) the rupture process of the Chi Chi earthquake source lasted about 32 seconds and the mainfaulting occurred between 6th to 21st second after the start of the ruptures and the high slip areawere mainly located at the northern segment of the fault. (2) The slip was dominated by thrustfaulting. The average rake angle was 64.5°, which was very consistent with those inverted by USGS,Harvard and CWB (Central Weather Bureau of Taiwan). The amount of the moment inverted in this paperwas 7.76x10^(20) NM, which was a slightly bigger than those inverted by USGS and Harvard. (3) Aclear nucleation step existed in the source faulting process and it lasted about 6 seconds. Themoment release rate accelerated obviously at the end of the nucleation step. The faulting startedfrom the southern segment and mainly occurred at the northern segment after 10 seconds. At the endof this paper, we analyzed the reliability of the inversion result via comparing with the GPSobservations and discussed its scientific signification.

关键词： Chi Chi earthquake, source rupture process, waveform inversion, near-source data, source mechanism.

Engineering graphene oxide and hydrogel coatings on fabrics for smart Janus textiles with superior thermal regulation

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Chinese Journal of Chemical Engineering 2024年第10期74卷 1-12页

作者： Weidong Wu Yukun Zeng chen zhou Xin zhou Shengyang Yang Department of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China College of Veterinary Medicine Yangzhou UniversityYangzhou 225009China Department of Physical Sciences University of Central MissouriWarrensburgMO 64093USA

Fabric multifunctionality offers resource savings and enhanced human *** study innovatively integrates cooling,heating,and antimicrobial properties within a Janus fabric,surpassing previous research focused solely on cooling or *** effects are achieved by applying distinct coatings to each side of the *** graphene oxide(GO)coating exhibits exceptional light-to-heat conversion,absorbing and transforming light energy into heat,thereby elevating fabric temperature by 15.4℃,22.7℃,and 43.7℃ under 0.2,0.5,and 1 sun irradiation,***,a hydrogel coating on one side absorbs water,facilitating heat dissipation through evaporation upon light exposure,reducing fabric temperature by 5.9℃,8.4℃,and 7.1℃ in 0.2,0.5,and 1 sun irradiation,***,both sides of Janus fabric exhibit potent antimicrobial properties,ensuring fabric *** work presents a feasible solution to address crucial challenges in fabric thermal regulation,providing a smart approach for intelligent adjustment of body comfort in both summer and *** integrating heating and cooling capabilities along with antimicrobial properties,this study promotes sustainable development in textile techniques.

关键词： Janus fabric Heat transfer Membranes Gels Evaporation Bacterial resistance

Selecting between Sequential Zoning and Simultaneous Zoning for Picker-to-parts Order Picking System Based on Order Cluster and Genetic Algorithm

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Chinese Journal of Mechanical Engineering 2011年第5期24卷 820-828页

作者： SHEN Changpeng WU Yaohua zhou chen School of Control Science and Engineering Shandong University Jinan 250061 China School of Industrial and Systems Engineering Georgia Institute of Technology Atlanta GA 30332 USA

The existing research of sequential zoning system and simultaneous zoning system mainly focuses on some optimization problems such as workload balance,product assignment and simulation for each system *** there is little research on comparative study between sequential zoning and simultaneous *** order to help the designers to choose the suitable zoning policy for picker-to-parts system reasonably and quickly,a systemic selection method is ***,both zoning and batching are order clustering,so the customer order sheet can be divided into many unit *** the time formulation in one-dimensional unit was defined,the time models for each zoning policy in two-dimensional space were established using filling curves and sequence models to link the one-dimensional unit *** consideration of ＂U＂ shaped dual tour into consideration,the subtraction value of order picking time between sequential zoning and simultaneous zoning was defined as the objective function to select the suitable zoning policy based on time *** it is convergent enough,genetic algorithm is adopted to find the optimal value of order picking *** the experimental study,5 different kinds of order/stock keeping unit（SKU） matrices with different densities d and quantities q following uniform distribution were created in order to test the suitability of sequential zoning and simultaneous zoning to different kinds of *** parameters setting,experimental orders inputting and iterative computations,the optimal order picking time for each zoning policy was *** observing whether the delta time between them is greater than 0 or not,the suitability of zoning policies for picker-to-parts system were *** significant effect of batch size b,zone number z and density d on suitability was also found by experimental *** proposed research provides a new method for selection between sequential zoning and simultaneous zoning for picker-to-parts syst

关键词： selecting sequential zoning simultaneous zoning order cluster genetic algorithm picker-to-parts

Numerical study of radio wave propagation in clear air acoustic scatterer

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Journal of Systems Engineering and Electronics 2018年第4期29卷 684-692页

作者： WANG Panpan zhou chen ZHAO Zhengyu Department of Space Physics School of Electronic Information Wuhan University

This paper numerically investigates the radio wave scattering by the artificial acoustic disturbance in the atmospheric boundary layer. The numerical model is based on the finitedifference time-domain（FDTD） method for radio wave propagation and fluid simulation for atmospheric disturbance by acoustics waves. The characteristics of radio wave scattering propagation in the artificial acoustic perturbations are investigated by this numerical model. The numerical simulation results demonstrate that the radio wave propagation scattered by acoustic scatterer has the characteristic of forward tropospheric scatter. When the radio waves are scattered, they distribute in all directions; a majority of radio waves continues to propagate along the original direction, and only a small part of the energy is scattered. For the same acoustic scatterer, if we merely change the radio wave emission elevation, the horizontal spans of forward scattering radio wave packets centers gradually decrease with the increasing of emission elevations; and the energy of wave packets increases firstly and then decreases with launching elevation, reaching the maximum at a certain angle. If we merely change the wave emitting position, the horizontal spans decrease with the increasing of emission positions, and the energy of wave packets also increases firstly and then decreases with launch position, reaching the maximum at a certain position. This approach can be very promising for atmospheric scatter communications.

关键词： radio waves scattering propagation clear air atmo-sphere acoustic scatterer scatter communication.

How Can Machine Learning and Optimization Help Each Other Better?

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Journal of the Operations Research Society of China 2020年第2期8卷 341-351页

作者： zhou-chen Lin Key Laboratory of Machine Perception School of Electronics Engineering and Computer SciencePeking UniversityBeijing 100871China

Optimization is an indispensable part of machine learning as machine learning needs to solve mathematical models *** the other hand,machine learning can also provide new momenta and new ideas for *** paper aims at inv... 详细信息

关键词： Optimization Machine learning Generalization ability Data

TWO IMPROVED ALGORITHMS AND IMPLEMENTATION FOR A SINGULARLY PERTURBED PROBLEM ON MOVING MESHES

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Journal of Systems Science & Complexity 2011年第6期24卷 1232-1240页

作者： Qin zhou Yanping chen Yin YANG School of Mathematics Hunan International Economics University Changsha 410205 China School of Mathematical Sciences South China Normal University Guangzhou 510631 China School of Mathematics and Computational Science Xiangtan University Xiangtan 411105 China

This paper applies a difference scheme to a singularly perturbed problem. The authors provide two algorithms on moving mesh methods by using Richardson extrapolation which can improve the accuracy of numerical solution. In traditional algorithms of moving meshes, the initial mesh is a uniform mesh. The authors change it to Bakhvalov-Shishkin mesh, and prove that it improves efficiency by numerical experiments. Finally, the results of the two algorithms are analyzed.

关键词： Algorithm equidistribution principle moving mesh method Richardson extrapolation singularly perturbed problem.