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

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 separately.But there is little research on comparative study between sequential zoning and simultaneous zoning.In order to help the designers to choose the suitable zoning policy for picker-to-parts system reasonably and quickly,a systemic selection method is presented.Essentially,both zoning and batching are order clustering,so the customer order sheet can be divided into many unit grids.After 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 grids.In 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 models.As it is convergent enough,genetic algorithm is adopted to find the optimal value of order picking time.In 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 orders.After parameters setting,experimental orders inputting and iterative computations,the optimal order picking time for each zoning policy was gotten.By observing whether the delta time between them is greater than 0 or not,the suitability of zoning policies for picker-to-parts system were obtained.The significant effect of batch size b,zone number z and density d on suitability was also found by experimental study.The proposed research provides a new method for selection between sequential zoning and simultaneous zoning for picker-to-parts system,and improves the rationality and efficiency of selection process in practical design.     

An overview of seismic ground motion design criteria for transportation infrastructures in USA

This paper provides an overview of current seismic ground motion criteria for transportation infrastructures in USA.This is to facilitate an understanding of current seismic performance levels and design practices in USA for transportation professionals world-wide,especially those in Asian and Pacific regions.Seismic vulnerability of a transportation infrastructure is determined by the risk associated with the seismic ground motion and specified performance criteria.Determining an acceptable seismic risk is...     

Advanced strain engineering for state-of-the-art nanoscale CMOS technology

The introduction and advancement of strain engineering has been one of the most critical features for the state-of-the-art nanoscale CMOS transistors. This paper provides an overview of the major strain engineering techniques that have remarkably re-shaped the advanced CMOS transistor architecture, including embedded SiGe (eSiGe), embedded Si:C (eSi:C), stress memorization technique (SMT), dual stress liners (DSL), and stress proximity technique (SPT). The advent of high-K/metal-gate (HKMG) also brings in a...     

具有热调节性能的膜材料在建筑结构中的应用

最新开发的用于建筑膜结构材料的含有PCM的硅橡胶涂层的基布使得以前的建筑膜结构织物的热性能得到了明显的提高.热性能的提高同样会导致使用膜材料作为屋顶或外围的建筑物的热能管理得到明显改善.增强的热能管理可以有效降低建筑物空调和供暖的需求,从而使建筑物更加节能.     

回收再利用PET瓶片的增值

消费后PET瓶子的回收再利用一般用于纺织品（或服装）、地毯、薄膜以及注塑制品。相对于其他级别的PET,瓶级PET质量较高,并具有较好的性能。为生产高性能的PET产品,恢复这种等级很重要。PET瓶片的等级可以通过固相聚合（SSP）进一步提高。     

直角折线斯戴纳问题和最小化直角折线斯戴纳树（MRST）布线

直角折线斯戴纳问题是高密度多层布线，组合图论和计算理论的基础，本文介绍直角折线斯戴纳问题的通解理论，对给定精度有效求解的方法和它们在高密度布线中的应用。     

大学与国家公园的合作伙伴关系：课堂、户外实验室与世界之窗

2016年美国国家公园系统庆祝其成立100周年。在过去的100年间,作为国家公园的合作伙伴,美国的大学一直致力于为国家公园提供科学、教育和培训方面的支持。在中小学阶段,国家公园就成为学生们的学习场所。大学生在读期间会以实习生和季节工的身份参加国家公园的实践。研究生在完成论文和论文项目时为国家公园提供必要的研究,而所有参与者也就成了传递国家公园价值的更好的老师。这种支持有助于实现公园保护目标、解决公园面临的问题。同时,为在校学生和毕业后的学生提供了丰富学习经验的平台。为此还成立了专门的行政机构,以促进学校与公园的沟通、签订合约、建立合作伙伴。美国的大学与国家公园共同创造了一种有利于学术研究和管理实践的强有力合作伙伴关系,为世界以及中国国家公园体制的建设树立了很好的榜样。     

构建中国国家公园体系路径中的挑战与机遇

新的国家公园体系是中国在自然和文化遗产保护方面迈出的重要一步,为自然和文化遗产保护提供了重要的基石,同时也为游客提供了全新的体验机会。"为什么(建立国家公园体系)""怎么样(国家公园体系未来有哪些特征)"和"做什么(来建立国家公园体系)"是帮助建立国家公园体系、应对相关挑战和机遇的3条可行路径。此外,为了同步整合这3条路径,还需要一条路径解决政策和程序方面的问题。值得一提的是,在"为什么"方面,国家公园体系不仅应当保护生态完整性,也应当致力于提供转变性的游客体验机会。这些体验能够激励游客学习,掌握更多的信息,激励他们去探索更多地方。而"做什么"的问题涉及路径的其他方面,其中最重要的是要在充满不确定性和变化的全球背景下建立规划和管理的能力。