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61.
Let G be a graph. The connectivity of G, κ(G), is the maximum integer k such that there exists a k-container between any two different vertices. A k-container of G between u and v, Ck(u,v), is a set of k-internally-disjoint paths between u and v. A spanning container is a container that spans V(G). A graph G is k-connected if there exists a spanning k-container between any two different vertices. The spanning connectivity of G, κ(G), is the maximum integer k such that G is w-connected for 1≤wk if G is 1-connected.Let x be a vertex in G and let U={y1,y2,…,yk} be a subset of V(G) where x is not in U. A spanningk−(x,U)-fan, Fk(x,U), is a set of internally-disjoint paths {P1,P2,…,Pk} such that Pi is a path connecting x to yi for 1≤ik and . A graph G is k-fan-connected (or -connected) if there exists a spanning Fk(x,U)-fan for every choice of x and U with |U|=k and xU. The spanning fan-connectivity of a graph G, , is defined as the largest integer k such that G is -connected for 1≤wk if G is -connected.In this paper, some relationship between κ(G), κ(G), and are discussed. Moreover, some sufficient conditions for a graph to be -connected are presented. Furthermore, we introduce the concept of a spanning pipeline-connectivity and discuss some sufficient conditions for a graph to be k-pipeline-connected.  相似文献   
62.
The Service Allocation Problem (SAP) is a tactical problem arising in the yard management of a container transshipment terminal. The objective is the minimization of the container rehandling operations inside the yard. This study of the SAP was undertaken for the Gioia Tauro port which is located in Italy and is the main hub terminal for container traffic in the Mediterranean Sea. The SAP can be formulated as a Generalized Quadratic Assignment Problem (GQAP) with side constraints. Two mixed integer linear programming formulations are presented. The first one exploits characteristics of the yard layout at Gioia Tauro where the berth and the corresponding yard positions extend along a line. The second formulation is an adaptation of a linearization for the GQAP. In both cases only small instances can be solved optimally. An evolutionary heuristic was therefore developed. For small size instances the heuristic always yields optimal solutions. For larger sizes it is always better than a truncated branch-and-bound algorithm applied to the exact formulations.  相似文献   
63.
针对集装箱码头提箱作业过程中,由于外集卡的提箱顺序与目标箱在堆场的堆存位置不匹配导致大量翻箱这一难题,以码头的作业成本和外集卡的延误成本之和最小为目标,建立堆场翻箱与外集卡提箱顺序同步优化模型,优化外集卡的提箱顺序、龙门吊的任务分配以及翻箱方案。设计基于动态规划的启发式算法求解模型,并利用算例对模型与算法的有效性进行了验证。结果表明:与目前码头普遍采用的提箱方式相比,通过调整外集卡提箱顺序并同时优化翻箱方案以及龙门吊的任务分配可以降低堆场翻箱率,减少龙门吊的移动成本,从而节省提箱作业的总成本。  相似文献   
64.
针对内河集装箱运输增长与内河航道制约所导致的集装箱运输系统运作效率与航运安全问题,讨论长江上游集装箱码头泊位-锚地系统最优配置策略.通过构建码头泊位-锚地系统的船舶候泊排队服务模型,推导出队长水平状态的稳态概率分布,计算出平均等待队长,并建立泊位-锚地系统配置模型,采用数值算例考察相应的最优配置策略和锚泊溢出概率.  相似文献   
65.
绝热气缸-导热活塞系统的振动特性   总被引:1,自引:0,他引:1  
朱涵  周阳 《大学物理》2003,22(4):35-37
用计算机模拟的方法研究了绝热气缸中导热活塞的振动特性。在自由振动或受迫振动的情况下,系统在总体上都是和一个普通的阻尼振子相似的。与此同时,本也指明并分析了该热力学系统的一些独特而有趣的性质。  相似文献   
66.
《Electroanalysis》2004,16(16):1299-1304
As a result of industrialization lead is one of the most widely dispersed toxic heavy metals in the environment. There is a pressing need for a reliable, affordable and portable analytical technique for routine determination of lead at trace levels in biological and environmental samples. Despite their potential for portability and low cost, the currently available electrochemical stripping methods still have limited commercial availability. Among the reasons are the relatively large sample volumes and the large amount of reagents needed (1–3 mL), lower than required precision, and the inconvenience of a rotated electrode system. The Rotating Sample System is a unique approach to electrochemical stripping, devised for 20 μL sample droplets utilizing a large surface area electrode. This design combines the advantages of a microelectrode and a rotated electrode system. The semispherical sample drop itself is rotated by a fine gas jet directed at it tangentially, eliminating the need for a sample container. Neither fine moving mechanical parts nor sophisticated controls are required. The detection limit for lead(II) was found low enough and the reproducibility is sufficient for routine determinations in biomedical samples (5 ppb, 6%). The system can support a CDC recommended screening for blood lead levels and an on‐site analysis of environmental samples as well. Under suitable conditions calibration free direct determinations can also be performed.  相似文献   
67.
张坤鳌  李俊  方欣 《应用声学》2016,24(8):60-60
为降低PLC控制单容器液位控制系统的设计难度及成本,本系统选用STM32和STC89C51分别作为上位机与下位机的处理器,设计了基于Modbus-RTU协议的液位监控系统;实现了数据实时采集、显示与报警功能;采用PID算法很好的实现了凝结水液位恒值控制,满足了设计要求;最后给出了系统的实物图和测试结果。实验表明,该系统经济实用,抗干扰能力强,可以在工业控制中广泛使用。  相似文献   
68.
既有的交通运输行业绩效评价指标多是基于单种运输方式进行定义和统计, 不能满足未来以“协同”为典型特征的集装箱运输发展要求. 本文从运输能力、集疏运成本、服务质量和可持续性4个方面入手, 为集装箱港口3种集疏运方式建立统一的绩效评价指标体系. 为了充分反映客观信息和决策者的主观经验, 将层次分析法(主观赋权法)与熵值法(客观赋权法)相结合形成综合集成赋权法计算每个指标的复合权重, 并以宁波舟山港为研究对象, 对方法的合理性和有效性进行了案例验证和敏感性分析. 研究结果与宁波舟山港集疏运发展现状基本一致, 从而验证了指标体系的可行性, 为深入研究未来集装箱多式联运系统绩效评价提供了科学有效的指标依据.  相似文献   
69.
本文从球形容器中理想气体入手,用一种简单易懂且不失一般性的方法,推导出理想气体压强公式。  相似文献   
70.
Xuejun Liu 《Tetrahedron》2009,65(35):7303-5095
The syntheses of two water-soluble octahedral polyammonium nanocapsules 5e and 5f are described. Nanocapsule 5e was prepared via the TFA-catalyzed condensation reaction of six MOM-protected 4-hydroxybutyl-footed tetraformyl cavitands 3c with 12 ethylene diamines, followed by reduction and acidic hydrolysis of the intermediate octahedral polyimino nanocapsule. Nanocapsule 5f was prepared from 5e via the oxidation of the 4-hydroxybutyl feet to 3-carboxypropyl feet. Both nanocapsules are soluble in water below pH 5. 5f is also water-soluble above pH 7. In acidic aqueous solution, nanocapsule 5e encapsulates small negatively charged, partially hydrophobic guests, such as p-toluenesulfonic acid, N-BOC-aspartic acid, or 4-methylumbelliferyl phosphate. The single site microscopic binding constants for the latter guests are 150±30, 510±50, 1550±150 M−1, respectively and were determined from 1H NMR titrations and DOSY experiments by assuming a 6:1 binding model with six identical, independent binding sites per nanocapsule (statistical binding). 5e doesn't bind small neutral hydrophobic molecules in aqueous solution. However, both nanocapsules bind to nucleotides, such as ATP, dAMP, dGMP or TTP. NMR experiments support that nucleotides are not encapsulated, but bind to the outside of the nanocapsules.  相似文献   
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