A new mixed integer program and extended look-ahead heuristic algorithm for the block relocation problem

This paper considers the block relocation problem (BRP), in which a set of identically-sized items is to be retrieved from a set of last-in-first-out (LIFO) stacks in a specific order using the fewest number of moves. The problem is encountered in the maritime container shipping industry and other industries where inventory is stored in stacks. After surveying the work done on the BRP, we introduce “BRP-III”—a new mathematical formulation for the BRP—and show that it has considerably fewer decision variables and better runtime performance than the other formulation in the literature. We then introduce a new look-ahead algorithm (LA-N) that is an extension of the algorithms from the literature and show that the new algorithm generally obtains better solutions than the other algorithms and has minimal CPU runtime.     

An integrated model for screening cargo containers

This paper focuses on detecting nuclear weapons on cargo containers using port security screening methods, where the nuclear weapons would presumably be used to attack a target within the United States. This paper provides a linear programming model that simultaneously identifies optimal primary and secondary screening policies in a prescreening-based paradigm, where incoming cargo containers are classified according to their perceived risk. The proposed linear programming model determines how to utilize primary and secondary screening resources in a cargo container screening system given a screening budget, prescreening classifications, and different device costs. Structural properties of the model are examined to shed light on the optimal screening policies. The model is illustrated with a computational example. Sensitivity analysis is performed on the ability of the prescreening in correctly identifying prescreening classifications and secondary screening costs. Results reveal that there are fewer practical differences between the screening policies of the prescreening groups when prescreening is inaccurate. Moreover, devices that can better detect shielded nuclear material have the potential to substantially improve the system’s detection capabilities.     

A Closed Metallomolecular Cage that can Open its Aperture by Disulfide Exchange

A closed metallomolecular cage based on the tris(saloph) framework, in which its aperture can be opened by disulfide exchange, was designed. At the apertures of the molecular cage, bridging diamine ligands having a disulfide bond were introduced to close the cage structure. These bridging ligands efficiently blocked the uptake of a guest, Cs⁺, but the presence of a thiolate anion significantly accelerated the guest uptake. This clearly means that this cage complex became open by the addition of the thiolate anion, because the cage closure becomes more dynamic due to the disulfide exchange reaction.     

Multi-compartment containers from a mixture of natural and synthetic lipids

Small anionic liposomes were electrostatically adsorbed on the surface of larger cationic liposomes thus forming multi- compartment complexes composed exclusively of natural and synthetic lipids. The complexes contained two dozen anionic liposomes per a single cationic liposome and showed low cytotoxicity and ability to enzyme-induced bio-degradation. The liposomal multi-compartment complexes demonstrate great application potential as containers for drug encapsulation and delivery.     

基于可调谐二极管激光吸收光谱技术的密闭玻璃容器中水汽浓度及压力的探测

冻干法处理过的药品瓶中残存的水汽(H₂O)是药品变质的主要影响因素之一, 如何快速准确地测量瓶中的水汽浓度及压力, 是检测药瓶是否泄漏的关键. 本文报道了利用1.39 μm半导体激光器作为光源, 结合波长调制吸收光谱技术, 实现了对密闭玻璃容器(药瓶)中水汽浓度及压力的探测, 并通过转台模拟生产线对系统在动态条件下的性能进行了测试. 研究结果表明, 在0.2%-12%的H₂O浓度范围内真实值与测量值之间的相关度和标准偏差为0.9978 和4.81%, 在0.1-100 atm (1 atm=1.01325×10⁵ Pa)的压力范围内两者之间的相关度和标准偏差为0.982和5.6%, 系统对应的压力及浓度的最低检测限约为2.5 Torr (1 Torr=1.33×10² Pa)和400 ppm. 通过利用转台以及Labview编写的快速在线处理软件进行了动态条件下的测试, 一分钟可以处理300个左右的药瓶, 可以很好地满足快速实时探测的要求. 该方案可以直接应用于药瓶在线检测, 并且使用2台激光器可以实现多组分同时探测分析(如H₂O、氧气等).     

Principles of Combinatorial Optimization Applied to Container-Ship Stowage Planning

In this paper, a methodology for generating automated solutions to the container stowage problem is shown. The methodology was derived by applying principles of combinatorial optimization and, in particular, the Tabu Search metaheuristic. The methodology progressively refines the placement of containers, using the Tabu search concept of neighbourhoods, within the cargo-space of a container ship until each container is specifically allocated to a stowage location. Heuristic rules are built into objective functions for each stage that enable the combinatorial tree to be explored in an intelligent way, resulting in good, if not optimal, solutions for the problem in a reasonable processing time.     

Influence of container material on the heat transfer characteristics of nanofluids

The average and local thermal conductivity measurements of water-based Ag-nanofluid held in polypropylene and metallic containers using transient hot-wire method revealed a new phenomenon. The local thermal conductivity of water-based Ag nanofluid measured at different locations of containers was found to depend strongly upon the metallic container, but not on the polypropylene container. Similar observations have been found in water-based NiAl nanofluid, but not in water-based Al₂O₃ nanofluid. In contrast, this phenomenon was not observed for ethylene glycol-based Ag nanofluid, possibly due to the insignificant charge on the container wall, which partly explains the diversity in thermal conductivity by different researchers.     

适用于真空管道交通的高温超导磁悬浮车低温液氮容器

真空管道运输系统的建成以及在全球的普及与应用,将是继火车、汽车、飞机和IT之后人类的又一大福祉。将使今天面临的交通困境从根本上得以解决,也将给全球经济与社会生活方式带来全新的变化。磁悬浮车是真空管道交通系统的运行主体,在各种不同模式的磁悬浮车中,高温超导磁悬浮车非常适合于真空管道交通。然而,由于真空管道中是低压环境,用于常压环境的高温超导磁悬浮车低温液氮容器不适合直接用于真空管道交通系统。提出在真空管道交通中,采用带压力阀的高温超导磁悬浮车低温液氮容器。这是一种压力容器,器壁要承受压差,当前常用的矩形高温超导磁悬浮车低温液氮容器则不适合,进一步提出能承受较高压力的圆柱形低温液氮容器的设计构想。还对真空管道交通中真空环境对提高液氮容器保温效果的意义进行了讨论。     

沿海港口集装箱空箱调运策略优化模型

我国沿海港口进出口箱分布非常不均衡,由此产生了集装箱空箱调运现象,合理的空箱调运策略能够有效地降低航运成本。本文研究了沿海港口间的空箱调运问题。在传统确定目的港策略的基础上,提出了一种新的空箱调运策略,不确定目的港策略。针对两种不同调运策略分别建立了以总调运费用最小为目标的规划模型。并以中国沿海港口空箱调运为例,运用遗传算法,在不同的空箱供需情况下,对两种调运策略费用进行了优化求解。结果表明,供需平衡模式下,固定目的港策略略有优势;在供需不平衡模式中,不确定目的港策略优势更加明显。此研究能够为港口间空箱调运提供辅助决策。     

ICP-MS法测定陶瓷食品包装容器中的重金属

采用电感耦合等离子体质谱法(ICP-MS)同时测定了陶瓷食品包装容器中的重金属元素铅、镉、铬、钴、镍、锌、锑,并对影响测量的各因素进行了详细的研究。该方法的检出限为0.002～0.18 μg·L-1,加标回收率为95.8%～104.4%,相对标准偏差为1.1%～3.3%。该方法快速、简便、具有较好的准确度和精密度,对进出品陶瓷制品的日常检验提供了依据。