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二氧化碳在多孔水泥充填材料中的扩散与反应动力学响应

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采矿与安全工程学报 2019年第2期36卷 381-387页

作者：王鹏 chen shen’en 陈占清茅献彪中国矿业大学力学与土木工程学院江苏徐州221116 美国北卡罗来纳大学夏洛特分校土木与环境工程学院北卡罗来纳夏洛特28262

综合运用反应动力学和连续介质力学理论,建立了CO_2在水泥孔隙介质扩散的过程中含有10个质量浓度和7个反应速率的化学反应动力学模型,并利用遗传算法对模型中9个决策参量分别进行了优化。通过数值模拟研究了孔隙度、扩散系数、扩散速率... 详细信息

综合运用反应动力学和连续介质力学理论,建立了CO_2在水泥孔隙介质扩散的过程中含有10个质量浓度和7个反应速率的化学反应动力学模型,并利用遗传算法对模型中9个决策参量分别进行了优化。通过数值模拟研究了孔隙度、扩散系数、扩散速率、反应级数、反应速率和组分浓度沿试样高度方向分布特征。研究表明:1)孔隙度、扩散系数和扩散速率沿试样高度方向单调减小,随时间单调增大。2)当反应持续到12,24,48 h,上下端CO_2质量浓度差依次减小3.03,1.99,1.62kg/m3。3)在试样上端面附近CO_2质量浓度随单调减小,在试样下端面附近质量浓度随单调增大,在中间截面上质量浓度先升后降。4)由于反应级数的跳跃,氢氧化钙、硅酸三钙和CO_2质量浓度及其变化率出现轻微的抖动。根据数值模拟结果与实验结果对比表明该模型可以精确的分析CO_2在多孔水泥充填材料中的吸附过程,可以定量定性的分析CO_2矿物碳酸化存储效果。

关键词：水泥充填胶结材料 CO2 扩散反应速率反应级数质量浓度

Experimental optimization and mathematical modeling of supercritical carbon dioxide extraction of essential oil from Pogostemon cablin

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Chinese Journal of Chemical engineering 2019年第10期27卷 2407-2417页

作者： Kangning Xiong Yun chen Shuai shen Department of Chemistry and Chemical engineering South China University of TechnologyGuangzhou 510640China

The supercritical carbon dioxide extraction was applied to obtain essential oil from Pogostemon cablin in this *** of extraction parameters including temperature,pressure,extraction time and particle size on extraction yield was investigated,and the response surface methodology with a Box–Behnken Design was used to achieve the optimized extraction *** maximum yield of essential oil was 2.4356%under the conditions of extraction temperature 47°C,pressure 24.5 MPa and extraction time 119 ***,based on the Brunauer–Emmett–Teller theory of adsorption,a mathematical modeling was performed to correlate the measured *** model shows a function relationship between extraction yield and time by a simple equation with three significantly adjustable *** model parameters have been optimized through simulated annealing *** predicted data from the mathematical model show a good agreement with the experimental data of the different extraction parameters.

关键词： Supercritical carbon dioxide extraction Pogostemon cablin Response surface methodology Mathematical modeling Simulated annealing algorithm

Reliability of weak signals detection in neurons with noise

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Science China(Technological Sciences) 2016年第3期59卷 411-417页

作者： shen YueLing YU LianChun chen Yong Department of Physics Gansu University of Chinese Medicine Lanzhou 730000 China Institute of Theoretical Physics Lanzhou University Lanzhou 730000 China Center of Soft Matter Physics and Application Beihang University Beijing 100191 China School of Physics and Nuclear energy engineering Beihang University Beijing 100191 China

Previous experimental and theoretical studies have demonstrated that a weak signal can be amplified and optimized by the assistance of noise. The response of the system undergoes stochastic resonance(SR) like behavior. The underlying mechanisms are fairly simple and robust. This phenomenon has been observed in a large variety of systems, including physical and biological systems. In the nervous system, the majority of synaptic input is too weak to make neurons fire a spike. This weak(or subthreshold) signals detection is very important for animal survival, and pulse detection is a simple but basic task of neuronal information transmission and processing. Some studies have found that subthreshold signals can be transmitted by the application of external noise. However, neurons are subjected to various kinds of inherent noise. Recently, theoretical work has revealed that this inherent noise improves signals detection ability. The detection ability of a single neuron is limited, and the neuronal circuit can perform this task very well by detecting the synchronization of presynaptic potentials. Here, we review recent studies of subthreshold detection by both single neurons and neuronal circuits.

关键词： stochastic resonance synchrony coincidence detection reliability precision

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

Flexural Mechanical Properties of Functional Gradient Hydroxyapatite Reinforced Polyetheretherketone Biocomposites

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Journal of Materials Science & Technology 2016年第1期32卷 34-40页

作者： Yusong Pan Yan chen Qianqian shen Laboratory of Multiscale Materials and Molecular Catalysis School of Material Science & EngineeringAnhui University of Science and Technology

Functional gradient hydroxyapatite reinforced polyetheretherketone is one of the most promising or- thopedic implant biomaterials. In this study, functional gradient hydroxyapatite reinforced polyetheretherketone biocomposites were prepared by layer-by-layer method with the incorporation of hot press molding technology. Studies on the flexural mechanical properties of the functional gradient biocomposites revealed that the flexural stress-stain behavior of the biocomposites presented linear elastic characteristics. The fracture mechanism of the functional gradient biocomposites was predominated by brittle rupture. Furthermore, both flexural strength and break strain of the functional gradient HA/PEEK biocomposites obviously decreased with the rise of the total HA content. The effect of hydroxyapatite concentration difference between adjacent layers （HCDBAL） on the flexural strength obviously relied on the level of HCDBAL and total HA content in the functional gradient HA/PEEK biocomposites. The higher the total HA content in the functional gradient biocomposites is, the less the influence degree of HCDBAL on the flexural strength is. Moreover, total HA content and HCDBAL played synergistic influence on the flexural modulus of the functional gradient HA/PEEK biocomposites.

关键词： Hydroxyapatite Functional gradient HA/PEEK biocomposites Flexural strength Flexural modulus

Evaluation of commutation failure risk in single-or multi-infeed LCC-HVDC systems based on equivalent-fault method

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Science China(Technological Sciences) 2018年第8期61卷 1207-1216页

作者： ZHenG Kuan shen chen LIU Feng State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University

In single-or multi-infeed line-commutated converter-based high-voltage direct current(LCC-HVDC) systems, commutation failure(CF) induced by alternating current(AC) faults may lead to serious consequences. Considering the randomness of fault occurrences, an accurate evaluation of the CF risk(CFR) from the system point of view becomes necessary in power system planning and operation. This paper first provides a definition of the CF severity(CFS) index corresponding to an AC fault. Then,on the basis of electromagnetic transient(EMT) simulation, an approach to calculate the CFS index considering the randomness of fault-occurrence time is presented. A novel equivalent-fault method is further put forward to make the EMT simulation scalable to calculate the CFS index in terms of a fault occurring in a large-scale receiving-end grid. Thereafter, the CFR index is introduced, which is defined as the sum of the products of the CFS index of each AC fault and the corresponding fault ***, the proposed method is verified on the modified IEEE 9-bus and modified IEEE 39-bus systems using PSCAD/EMTDC.

关键词： commutation failure severity equivalent-fault method commutation failure risk fault randomness electromagnetictransient simulations

NUMERICAL SIMULATION OF 3-D TURBULenT FLOW IN THE MULTI-INTAKES SUMP OF THE PUMP STATION

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Journal of Hydrodynamics 2007年第1期19卷 42-47页

作者： chen Hong-xun shen Xin-rong Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

In this article, a numerical model forthree-dimensional turbulent flow in the sump of the pumpstation was presented. A reasonable boundary condition for the flow in the sump with several water intakes at different flowrates was proposed. The finite volume method was employed tosolve the governing equations with the body fitted gridgenerated by the multi-block grid technique. By using theFluent software, the fluid flow in a model sump of the pumpstation was calculated. Compared with the experimental result,the numerical result of the example is fairly good.

关键词： pumping station sump suction pipe turbulentmodel numerical simulation

Learning and fatigue inspired method for optimized HTN planning

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Journal of Systems engineering and Electronics 2012年第2期23卷 233-241页

作者： Wanpeng Zhang Lincheng shen Jing chen College of Mechatronic engineering and Automation National University of Defense TechnologyChangsha 410073P.R.China

Learning is widely used in intelligent planning to shorten the planning process or improve the plan quality. This paper aims at introducing learning and fatigue into the classical hierarchical task network （HTN） planning process so as to create better high- quality plans quickly. The process of HTN planning is mapped during a depth-first search process in a problem-solving agent, and the models of learning in HTN planning is conducted similar to the learning depth-first search （LDFS）. Based on the models, a learning method integrating HTN planning and LDFS is presented, and a fatigue mechanism is introduced to balance exploration and exploitation in learning. Finally, experiments in two classical do- mains are carried out in order to validate the effectiveness of the proposed learning and fatigue inspired method.

关键词： hierarchical task network (HTN) planning learning fatigue.

EXISTenCE AND ANALYTICAL APPROXIMATIONS OF LIMIT CYCLES IN A THREE-DIMenSIONAL NONLINEAR AUTONOMOUS FEEDBACK CONTROL SYSTEM

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Journal of Systems Science & Complexity 2014年第6期27卷 1158-1171页

作者： chen Huaxiong shen Jianhe ZHOU Zheyan School of Mathematics and Computer Science Fujian Normal University

This paper is concerned with the existence and the analytical approximations of limit cycles in a three-dimensional nonlinear autonomous feedback control *** on three-dimensional Hopf bifurcation theorem,the existence of limit cycles is first *** the homotopy analysis method(HAM) is applied to obtain the analytical approximations of the limit cycle and its *** deriving the higher-order approximations,the authors utilized the idea of a perturbation procedure proposed for limit cycles' approximation in van der Pol *** comparing with the numerical integration solutions,it is shown that the accuracy of the analytical results obtained in this paper is very high,even when the amplitude of the limit cycle is large.

关键词： Homotopy analysis method Hopf bifurcation limit cycle three-dimensional nonlinearautonomous system.