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Search Results: 1 - 10 of 80856 matches for " LIU Mengcheng "
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Genetic Algorithm for Scattered Storage Assignment in Kiva Mobile Fulfillment System  [PDF]
Mengcheng Guan, Zhenping Li
American Journal of Operations Research (AJOR) , 2018, DOI: 10.4236/ajor.2018.86027
Abstract: Scattered storage means an item can be stored in multiple inventory bins. The scattered storage assignment problem based on association rules in Kiva mobile fulfillment system is investigated, which aims to decide the pods for each item to put on so as to minimize the number of pods to be moved when picking a batch of orders. This problem is formulated into an integer programming model. A genetic algorithm is developed to solve the large-sized problems. Computational experiments and comparison between the scattered storage strategy and random storage strategy are conducted to evaluate the performance of the model and algorithm.
Pod Layout Problem in Kiva Mobile Fulfillment System Using Synchronized Zoning  [PDF]
Mengcheng Guan, Zhenping Li
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.612213
Abstract: This article studies the pod layout problem in the Kiva mobile fulfillment system which adopts the synchronized zoning strategy. An integer programming model for the pod layout problem is formulated under the premise of knowing the relationship of the pods and items. A three-stage algorithm is proposed based on the Spectral Clustering algorithm. Firstly, the pod similarity matrix and the Laplacian matrix are constructed according to the relationship of the pods and items. Secondly, the pods are clustered by the Spectral Clustering algorithm and assigned to each zone based on the cluster results. Finally, the exact locations of pods in each zone are determined by the historical retrieval frequency of items, using the real data of a large-scale Kiva mobile fulfillment system to simulate and calculate the order picking efficiency before and after the adjustment of the pod layout. The results showed that the pod layout using synchronized zoning strategy can effectively improve the picking efficiency.
STUDY ON SHEAR BEHAVIORS OF ROCKFILL IN LARGE-SCALE TRIAXIAL TESTS UNDER DIFFERENT STRESS PATHS
应力路径条件下堆石料剪切特性大型三轴试验研究

LIU Mengcheng,GAO Yufeng,LIU Hanlong,
刘萌成
,高玉峰,刘汉龙

岩石力学与工程学报 , 2008,
Abstract: 依据宜兴抽水蓄能电站上库主坝主堆石料原型级配,联合采用相似级配和等量替代的级配模拟技术制备大型三轴试样,利用YS-30型应力路径大型试验机开展应力路径条件下堆石料剪切特性大型三轴试验研究.研究结果表明:应力路径与固结应力共同作用,成为影响堆石料剪切特性的主要外部因素.堆石料抗剪强度具有显著的非线性特征,而应力路径对其抗剪强度影响极小.随着σc与k的增加,应力-应变关系由低压应变软化、高压应变硬化型向完全应变硬化型转变;体积应变关系由低压剪胀、高压剪缩型向完全剪缩型转变;随着应力比k的增加,堆石料塑性变形性质逐渐由剪切塑性变形变化为主转变为压缩塑性变形变化为主,破坏形式则由剪切破坏转变为压缩破坏.堆石料剪胀剪缩转化关系由临界应力比kcrit与临界固结应力(σc)crit共同决定.
LARGE-SCALE TRIAXIAL TEST STUDY ON DEFORMATION AND STRENGTH CHARACTERISTICS OF ROCKFILL MATERIALS
堆石料变形与强度特性的大型三轴试验研究

Liu Mengcheng,GaoYufeng,Liu Hanlong,Chen Yuanhong,
刘萌成
,高玉峰,刘汉龙,陈远洪

岩石力学与工程学报 , 2003,
Abstract: The test results of two rockfill samples are obtained with large-scale testing equipment. Based on these results, some useful conclusions are drawn from the analysis of deformation in each direction and shear strength properties of the rockfills. Thus, the exponent formulations of the relationship between deviator stress and axial strain or lateral strain and axial strain are proposed, respectively. Besides, the failure envelopes of rockfills in the coordinate plane of octahedral shear stress and octahedral normal stress also can be described by the exponent formulation. At the same time, the inherent mechanism of experimental phenomena is discussed. The relations among dilation, particle breakage and rearrangement are analysed, and the concept of reciprocal transformation of elastic dilatancy and plastic dilatancy is put forward.
Unsupervised Multi-Level Non-Negative Matrix Factorization Model: Binary Data Case  [PDF]
Qingquan Sun, Peng Wu, Yeqing Wu, Mengcheng Guo, Jiang Lu
Journal of Information Security (JIS) , 2012, DOI: 10.4236/jis.2012.34031
Abstract: Rank determination issue is one of the most significant issues in non-negative matrix factorization (NMF) research. However, rank determination problem has not received so much emphasis as sparseness regularization problem. Usually, the rank of base matrix needs to be assumed. In this paper, we propose an unsupervised multi-level non-negative matrix factorization model to extract the hidden data structure and seek the rank of base matrix. From machine learning point of view, the learning result depends on its prior knowledge. In our unsupervised multi-level model, we construct a three-level data structure for non-negative matrix factorization algorithm. Such a construction could apply more prior knowledge to the algorithm and obtain a better approximation of real data structure. The final bases selection is achieved through L2-norm optimization. We implement our experiment via binary datasets. The results demonstrate that our approach is able to retrieve the hidden structure of data, thus determine the correct rank of base matrix.
STABILITY ANALYSIS OF THE SUBLEVEL CAVING METHOD

CHEN Junyan,SUN Mengcheng,

金属学报 , 1983,
Abstract: Ground control problems in subievel caving become evident as the rock pressure increases with depth. Recently, a finite element analysis of the stability problems of the sublevel caving method was completed by the authors. This paper summarizes the results of stress analysis in sublevel extraction drifts under different stress field conditions by using linear elastic and nonlinear elasto-plastic finite element modeling techniques. A critical stress concentration will occur in the uppermost sublevel drifts beneath the caved area or blasted ore area. During the blasting and drawing cycle, a tensile and shear failure condition could develop in the central extraction drift when it would be mined last. Under a high horizontal stress field condition, almost all tensile stress in the back of the extraction drifts will be eliminated and only slight yield can be seen in the floor of the extraction drifts. Compared to the cases under the gravitational stress field condition, the total yielding zone will be grtly reduced because of the increase of horizontal confining stress with depth. However, it is predicted that the centre of each ore column side will experience excessive shear stress that probably will result in ore failure.The two major conclusions drawn from this study to improve the overall stability of sublevel caving are: (1) the width of extraction drifts must be carefully controlled and an appropriate stoping sequence selected; and (2) the sublevel caving method can be used in deep mining if the pillar width is increased correspondingly with mining depth.
穿江隧道对堤防工程影响研究
Study on the influence of the cross-river tunnel to the embankment project

张贵金,刘丽玲,陈宏任,李梦成,
ZHANG Guijin
,LIU Liling,CHEN Hongren,LI Mengcheng

- , 2016,
Abstract: 采用数值方法,通过多工况模拟,分别对隧道的覆土厚度、隧道匝道出入口离堤防的距离、隧道主出入口与堤防的相对距离以及地下水等因素进行影响分析,研究堤防工程的渗透稳定及变形趋势。研究结果表明:在堤防工程的护堤地范围内,穿江隧道匝道出入口离堤防的距离越近且地下水位越低时,水力坡降越大,对堤防的渗流稳定越不利;但地下水位越高时,堤顶与地表沉降越大,对堤防的沉降稳定越不利。隧道覆土厚度几乎不影响堤防的水力坡降,但会影响堤防的沉降变形,覆土厚度必须按规范或经验限定。隧道主出入口与堤防的相对距离越近且地下水位越低时,水力坡降越大,但相对距离及地下水位的改变对沉降影响很小。
In this article the numerical method is used to simulate the seepage stability and deformation of the embankment engineering through multiple operating condition. By analysing tunnel''''s cover thicknees, distance from the entrance of ramp to the embankment, relative distance from the major entrance to the embankment and ground water, the seepage stability and deformation of the embankment is studied. It turns out that within the scope of the levee engineering, with closer distance from cross-river tunnel ramp entrances and exits to dike and lower underground water level. The hydraulic grade will be greater, which has worse effect on the seepage stability of the dike. But the higher underground water level, the greater the settlement of levee crest and ground surface are, which has worse effect on settlement stabilization. The tunnel’s cover thickness almost has no effect on the embankment’s hydraulic gradient, but it does affect the embankment’s settlement deformation. So that the cover thickness must be defined according to specifications or experience. With closer the distance from major entrance to the embankment and lower ground water level, the hydraulic gradient will be greater, and the change of relative distance and groundwater level has little effect on settlement
Microbial communities in microcosm soils treated with battery waste

Han Xuemei,Guo Weihua,Wang Renqing,Wang Mengcheng,

自然科学进展 , 2007,
Abstract: Battery waste is one of the most destructive hazards to our environment, especially to the soil. In order to understand the effects of the battery waste on the microbial communities in soil, microcosm soils were treated with the powder made from the battery waste. Microbial biomass and respiration were measured after 15, 30, 45, and 60 days of the treatment, and catabolic capability and Biolog profile were determined after 60 days. Microbial biomass was declined by all treatments, while microbial respiration and catabolic capability were enhanced. Although microbial biomass recovered after a period of incubation, microbial respiratory quotient, catabolic capability and community structure remained significantly affected. Our results also suggest that microbial respiratory quotient and Biolog parameters are more sensitive than microbial biomass to the battery stress on bioavailability.
Synonymous codon usage bias is correlative to intron number and shows disequilibrium among exons in plants
Qin Zhen,Cai Zhengqiu,Xia Guangmin,Wang Mengcheng
BMC Genomics , 2013, DOI: 10.1186/1471-2164-14-56
Abstract: Background Evidence has been assembled to suggest synonymous codon usage bias (SCUB) has close relationship with intron. However, the relationship (if any) between SCUB and intron number as well as exon position is at present rather unclear. Results To explore this relationship, the sequences of a set of genes containing between zero and nine introns was extracted from the published genome sequences of three algal species, one moss, one fern and six angiosperms (three monocotyledonous species and three dicotyledonous species). In the algal genomes, the frequency of synonymous codons of the form NNG/NNC (codons with G and C at the third position) was positively related to intron number, but that of NNA/NNT was inversely correlated; the opposite was the case in the land plant genomes. The frequency of NNC/NNG was higher and that of NNA/NNT lower in two terminal exons than in the interstitial exons in the land plant genes, but the rule showed to be opposite in the algal genes. SCUB patterns in the interstitial and two terminal exons mirror the different evolutionary relationships between these plant species, while the first exon shows the highest level of conservation is therefore concluded to be the one which experiences the heaviest selection pressure. The phenomenon of SCUB may also be related to DNA methylation induced conversion of CG to AT. Conclusions These data provide some evidence of linkage between SCUB, the evolution of introns and DNA methylation, which brings about a new perspective for understanding how genomic variation is created during plant evolution.
Development and psychometric properties of the health-risk behavior inventory for Chinese adolescents
Mengcheng Wang, Jinyao Yi, Lin Cai, Muli Hu, Xiongzhao Zhu, Shuqiao Yao, Randy P. Auerbach
BMC Medical Research Methodology , 2012, DOI: 10.1186/1471-2288-12-94
Abstract: Adolescents, ages 14–19?years (n?=?6,633), were recruited from high schools across 10 cities in mainland China. In addition, a clinical sample, which included 326 adolescents meeting DSM-IV criteria for Conduct Disorder, was used to evaluate predictive validity of the HBICA. Psychometric properties including internal consistency (Cronbach’s alpha), test-retest reliability, convergent validity, and predictive validity were analyzed.Based upon item analysis and exploratory factor analysis, we retained 33 items, and 5 factors explained 51.75% of the total variance: Suicide and Self-Injurious Behaviors (SS), Aggression and Violence (AV), Rule Breaking (RB), Substance Use (SU), and Unprotected Sex (US). Cronbach’s alphas were good, from 0.77 (RB) to 0.86 (US) for boys, and from 0.74 (SD) to 0.83(SS) for girls. The 8?weeks test–retest reliabilities were moderate, ranged from 0.66 (AV) to 0.76 (SD). External validities was strong, with Barratt Impulsiveness Scale-11 was 0.35 (p?<?0.01), and with aggressive behavior and rule-breaking behavior subscales of the Youth Self Report were 0.54 (p?<?0.01) and 0.68 (p?<?0.01), respectively. Predictive validity analysis also provided enough discriminantity, which can distinguish high risky individual effectively (cohen’ d?=?0.79 – 2.96).These results provide initial support for the reliability and validity of the Health-Risk Behavior Inventory for Chinese Adolescents (HBICA) as a comprehensive and developmentally appropriate assessment instrument for risk behaviors in Chinese adolescents.
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