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ORDER-PICKING OPTIMIZATION FOR AUTOMATED PICKING SYSTEM WITH PARALLEL DISPENSERS

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 25-29页

作者： wu Yaohua zhang Yigong College of Control Science and Engineering Shandong University Jinan 250061 China

Based on the characteristics of parallel dispensers in automated picking system, an order-picking optimization problem is presented. Firstly, the working principle of parallel dispensers is introduced, which implies the time cost of picking each order is influenced by the order-picking sequence. So the order-picking optimization problem can be classified as a dynamic traveling salesman problem （TSP）. Then a mathematical model of the problem is established and an improved max-min ant system （MMAS） is adopted to solve the model. The improvement includes two aspects. One is that the initial assignment of ants depends on a probabilistic formula instead of a random deployment; the other is that the heuristic factor is expressed by the extra picking time of each order instead of the total. At last, an actual simulation is made on an automated picking system with parallel dispensers. The simulation results proved the optimization value and the validity of improvement on MMAS.

关键词： Automated picking system Parallel dispensers Max-min ant system

Effects of bacteria on nitrogen and phosphorus release from river sediment

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Journal of Environmental Sciences 2008年第4期20卷 404-412页

作者： wu Qunhe zhang Renduo HUANG Shan zhang Hengjun School of Environmental Science and Engineering Sun Yat-Sen （Zhongshan） University Guangzhou 510275 China

To better understand the mechanisms of eutrophication, we addressed the microbial processes that influence many key aspects of water-sediment systems. In this study, a large column experiment was conducted for 30 d. Along the column, solution samples were collected at different locations at different time. The samples were analyzed for physical, chemical, and biological properties of the sediment and overlying water. The results showed that the amount of nitrogen transforming bacteria was higher than that of phosphorous bacteria. The amount of nitrogen transforming bacteria was in the order： ammonifier 〉 denitrifying bacteria 〉 nitrobacteria and nitrosomonas. Principal component analysis indicated that the three main factors accounted for more than 90% overall contributions for bacterium growth, which represented nutrition, organics and oxygen, and pH and redox potential （Eh） of the environment. Corresponding to the bacteria, the concentrations of nitrogen in the system was in the order： ammonia （NH4＋-N）〉 nitrate （NO3^--N）〉 nitrite （NO2^--N）. The fluxes of N and P clearly showed a temporal release and adsorption processes in the water-sediment system. The large magnitude of N fluxes suggested that N might act as an important contamination source for the water quality. However, P exchange between the sediment and overlying water was less intensive during the experiment.

关键词： eutrophication sediment P and N transforming bacteria

Effects of additives on the phase transformation, occurrence state, and the interface of the Ti component in Ti-bearing blast furnace slag

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International Journal of Minerals,Metallurgy and Materials 2016年第9期23卷 1029-1040页

作者： Li zhang wu zhang Ju-hua zhang Guang-qiang Li School of Materials and Metallurgy Northeastern University School of Materials Science and Engineering Shenyang Ligong University School of Materials and Metallurgy Wuhan University of Science and Technology

The influences of additives on the phase transformation, occurrence state, and the interface of the Ti component in Ti-bearing blast furnace slag were investigated. After oxidation, most of the Ti component in the slag was enriched into the perovskite phase, which served as the Ti-rich phase during the crystallization process. The phase transformation, occurrence state, and the interface of the Ti component were observed to be affected by the addition of different types of agents. During the oxidation process, titanaugite and Ti-rich diopside phases gradually transformed into non-Ti phases（anorthite： CaMgSi2O6 and CaAl2Si2O8） in the form of dendrites or columns, which were observed to be distributed at the surface of the perovskite phase. Several more cracks appeared along the grain boundaries of the perovskite phase after the addition of P2O5, facilitating the liberation of the perovskite phase. Composite additives combining both an acid and a base, such as CaO ＋ CaF2 or P2O5 ＋ CaF2, were used. We observed that the disadvantages of using single additives were successfully overcome.

关键词： blast furnace slag titanium additives phase transformation interfaces

Effect of methamidophos on soil fungi community in microcosms by plate count,DGGE and clone library analysis

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Journal of Environmental Sciences 2008年第5期20卷 619-625页

作者： LI Xinyu zhang Huiwen wu Minna zhang Yan zhang Chenggang Microbial Resources and Ecology Group Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China

Methamidophos was widely used a pesticide in northern China. The potential influences of methamidophos on soil fungal community in black soil were assessed by plate count, 28S rDNA-PCR-DGGE, and clone library analysis. Three methamidophos levels （50, 150, and 250 mg/kg） were tested in soil microcosms. Results from plate count during a 60-d microcosm experiment showed that high concentrations of methamidophos （250 mg/kg） could significantly stimulate fungal populations. DGGE （denaturing gradient gel electrophoresis） fingerprinting patterns showed a significant difference between the responses of culturable and total fungi communities under the stress of methamidophos. Shannon diversity indices calculated from DGGE profiles indicated that culturable fungi in all microcosms with methamidophos treatment increased after 1 week of incubation. However, the diversity indices of total fungi decreased in the first week, as compared to the stimulation of culturable fungi. At the 8th week, however, all the microcosms treated by methamidophos were similar to the control microcosms in community structure as suggested by the Shannon diversity indices for both culturable and total fungi. In contrast, after 1 week the fungal structure of culturable and unculturable both were disturbed to different extent under the stresses of methamidophos by clustering analysis. Clone sequencing analysis indicated the stimulation of pathogenic and unculturable fungal populations by methamidophos treatment, suggetsing potential risks of plant disease outbreak.

关键词： methamidophos clone sequencing DGGE (denaturing gradient gel electrophoresis) fungi diversity

Effect of mineral admixtures and repeated loading on chloride migration through concrete

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第9期11卷 683-690页

作者： wu-man zhang Heng-jing BA School of Transportation Science and Engineering Beihang University Beijing 100191 China School of Civil Engineering Harbin Institute of Technology Harbin 150006 China

The effect of fly ash (FA) and ground granulated blast furnace slag (GGBFS) on chloride migration through concrete subjected to repeated loading was examined. Portland cement was replaced by three percentages (20%, 30%, and 40%) of mineral admixtures. Five repeated loadings were applied to concrete specimens using a WHY series fully automatic testing machine. The maximum loadings were 40% and 80% of the axial cylinder compressive strength (f′c). Chloride migration through concretes was evaluated using the rapid chloride migration test and the chloride concentration in the anode chamber was measured. The results showed that the replacement percentages of mineral admixtures, the curing time and repeated loading had a significant effect on chloride migration through concrete. The transport number of chloride through concrete cured for 28 d increased with increasing FA replacement and markedly decreased with extension of the curing time. 20% and 30% GGBFS replacement decreased the transport number of chloride through concrete, but 40% GGBFS replacement increased the transport number. Five repeated loadings at 40% or 80% f′c increased the transport number of chloride for all mixes.

关键词： Concrete Fly ash (FA) Ground granulated blast furnace slag (GGBFS) Chloride migration Repeated loading

Modeling and Analysis of a Micromotor with an Electrostatically Levitated Rotor

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Chinese Journal of Mechanical Engineering 2009年第1期22卷 1-8页

作者： HAN Fengtian wu Qiuping zhang Rong Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China

The modeling and evaluation of a prototype rotary micromotor where the annular rotor is supported electrostatically in five degrees of freedom is presented in order to study the behavior of this levitated micromotor and further optimize the device geometry. The analytical torque model is obtained based on the principle of a planar variable-capacitance electrostatic motor while the viscous damping caused by air film between the stator and rotor is derived using laminar Couette flow model. Simulation results of the closed-loop drive motor, based on the developed dynamic model after eliminating mechanical friction torque via electrostatic suspension, are presented. The effects of the high-voltage drive, required for rotation of the rotor, on overload capacity and suspension stiffness of the electrostatic bearing system are also analytically evaluated in an effort to determine allowable drive voltage and attainable rotor speed in operation. The analytical results show that maximum speed of the micromotor is limited mainly by viscous drag torque and stiffness of the bearing system. Therefore, it is expected to operate the device in vacuum so as to increase the rotor speed significantly, especially for those electrostatically levitated micromotors to be used as an angular rate micro-gyroscope.

关键词： electrostatic levitation electrostatic micromotor variable-capacitance motor micro-gyroscope

Spatial–temporal characteristics of haze and vertical distribution of aerosols over the Yangtze River Delta of China

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Journal of Environmental Sciences 2018年第4期30卷 12-19页

作者： Yueqian Cao wu zhang Wenjing Wang Key Laboratory for Semi-Arid Climate Change of the Ministry of Education College of Atmospheric Sciences Lanzhou University

Variation of haze events occurred in the Yangtze River Delta（YRD） of China, the characteristics of meteorological elements and the vertical distribution of aerosols during haze episodes were analyzed by utilizing data of ground observation, radiosonde and CALIPSO. The results illustrate that the frequency of haze events between 1981 and 2010 peaked in winter but bottomed out in summer and decreased from north to south in the YRD region, reaching at the lowest point in ＂low frequency center＂ - Shanghai. When haze happened, the most seriously affected area was 2-4 km above the ground and the concentrated range of total backscattering coefficient（TBC） that decreased with altitude was 0.8 × 10^（-3）-2.5 × 10^（-3） km^（-1）·sr^（-1）. Particulate depolarization ratio（PDR） was less than 40%in a large part and 93% aerosols over the YRD area were regular particles, while the irregular ones concentrated on 2 km above the surface and the irregularity rose up but the diversity diminished when altitude increased. Color ratio（CR） was lower than 1.2 mostly at all altitudes and distributed asymmetrically above the ground. Nearly 80% aerosols under10 km were fine particles（CR 〈1.0） clustered at 2-4 km. Large particles（CR 〉 1.2） aggregated in lower troposphere massively yet relatively smaller ones gathered in middle and upper troposphere. In the YRD region, aerosols with more powerful capabilities were wider and less regular than the ones of Northwestern China.

关键词： Yangtze River Delta Haze Aerosol Spatial-temporal characteristics Vertical distribution

Frequency Analysis and Anti-Shock Mechanism of Woodpecker＇s Head Structure

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Journal of Bionic Engineering 2014年第2期11卷 282-287页

作者： Zhaodan Zhu Chengwei wu Wei zhang State Key Lab of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 P. R. China

The mechanical properties of the skull and the anti-shock characteristics of woodpecker＇s head were investigated by ex- periment and numerical simulation. We measured the micro-Young＇s modulus of the skull by nano-indentation method and calculated the macro-equivalent Young＇s modulus of the skull at different positions using homogenization theory. Based on the Computerized Tomography （CT） images of woodpecker head, we then built complete and symmetric finite element models of woodpecker＇s skull and its internal structure and performed modal analysis and stress spectrum analysis. The numerical results show that the application of pre-tension force to the hyoid bone can increase the natural frequency of woodpecker＇s head. The first natural frequency under the pre-tension force of 25 N reaches 57 Hz, which is increased by 21.3% from the non-pre-tension state and is more than twice the working frequency of woodpecker （20 Hz 25 Hz）. On the application of impact force to the tip of beak for 0.6 ms, high magnitudes of stress component occur at around 100 Hz and 8,000 Hz, far away from both the working frequencies and the natural frequencies of woodpecker head. The large gaps among the natural, working and stress response frequencies enable the woodpecker to effectively protect its brain from the resonance injury.

关键词： woodpecker anti-shock frequency modal analysis stress spectrum

Technical advancements and significance of circumlunar return and reentry spacecraft

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Science China(Technological Sciences) 2015年第4期58卷 738-745页

作者： YANG Meng Fei zhang wu PENG Jing zhang Gao China Academy of Space Technology Institute of Spacecraft System Engineering China Academy of Space Technology

As one of the vital steps in the 3rd phase of China＇s lunar exploration program （CLEP）, the circumlunar return and reentry spacecraft, developed by China Academy of Space Technology （CAST）, is used to demonstrate the key technologies of by- per-speed return and reentry spacecraft. The system configuration and flight process are presented in this paper, as well as the analysis of mission characteristics, the key technologies and the technical advancement during the R＆D progress. The significance of circumlunar return and reentry spacecraft is given at the end.

关键词： circumlunar return skip reentry technical advancement China's lunar exploration program (CLEP)