Transshipment Strategy for Managing Supply Disruption Risk

Inventory transshipment among retailers is an effective strategy to manage supply disruption risks. The expected profit functions and the optimal ordering decisions of two newsvendors who adopt transshipment strategy to cope with upstream unreliability are derived. It is proved that transshipment strategy enhances the retailer's profit,improves the service level for customers,and under special conditions improves the supplier's profit as well. It is therefore claimed that transshipment strategy may achieve a Pareto improvement.

Controlling the coal dust at transshipment point: A study of the foam-sol foaming device

In order to effectively control the dust at the transshipment point with foam-sol, this paper attempted to study the characteristics of dust diffusion at transshipment point and the foam-sol foaming device with diffusion outlet was also designed in this paper. To study the diffusion rules of coal dust, fluent discrete phase model was utilized in the numerical simulation, as the coal dust was thrown down at a horizontal velocity of 2.5 m/s. A foam-sol foaming device was designed, through which foaming agent could be automatically sucked into the Venturi by the negative pressure. The automatic controller was also equipped,which could transform the energy of the compressed air into the constant pressure difference so that the gelling agent could be qualitatively added into the gel container. The diffusion outlet that could spray out foam-sol in a continuous, conical and 3D manner was also designed. Moreover, this paper also carried out the contrast experiments on dust removal efficiency among water, aqueous foam and foam-sol. The results clearly show that the symmetrical whirlpools appeared below the inlet where the largest whirlpool diameter was 0.52 m, and the horizontal distance from swirl range to the inlet was approximately0.69 m. By using the self-designed foaming device, the foaming was multiplied by 30 times and the volume ratio with water and foaming agent reached 95%:5%. In this context, the gas pressure was controlled at 0.3 MPa, with gas flow at 15 m3/h and water flow at 0.5 m3/h, with water pressure controlled between0.34 and 0.36 MPa. The foam-sol has the highest dust removal efficiency than other agents.

Step-wise synthesis of work exchange networks involving heat integration based on the transshipment model

Due to the deterioration of serious energy dilemma,energy-conservation and emission–reduction have been the strategic target in the past decades,thus people have identified the vital importance of higher energy efficiency and the influence of lower carbon development.Since work exchange network is a significant part of energy recovery system,its optima design will have dramatically significant effect on energy consumption reduction in chemical process system.With an extension of the developed transshipment model in isothermal process,a novel step-wise methodology for synthesis of direct work exchange network(WEN)in adiabatic process involving heat integration is first proposed in this paper,where a nonlinear programming(NLP)model is formulated by regarding the minimum utility consumption as objective function and optimizing the initial WEN in accordance with the presented matching rules to get the optimized WEN configuration at first.Furthermore,we focus on the work exchange network synthesis with heat integration to attain the minimal total annual cost(TAC)with the introduction of heat-exchange equipment that is achieved by the following strategies in sequence:introducing heat-exchange equipment directly,adjusting the work quantity of the adjacent utility compressors or expanders,and approximating upper/lower pressure limits consequently to obtain considerable cost savings of expanders or compressors and work utility.Finally,a case taken from the literature is studied to illustrate the feasibility and effectiveness of the proposed method.

A Model for Analyzing the Transshipment Competition Relationship Between the Port of Hong Kong and the Port of Kaohsiung

The transshipment is an important issue in the current marine transportation. This paper constructed a mathematical programming model to elaborate the transshipment port selection for the shipping company. This model is tested by the data collected from the ports of Hong Kong and Kaohsiung. The results show that this model can be used to explain the transshipment competition relationship between the ports of Hong Kong and Kaohsiung well. A sensitivity analysis was also executed. The sensitivity analysis results showed that both the port of Hong Kong and Kaohsiung should decrease the charges of port and increase the effi- ciency of loading and discharging. Based on the sensitivity analysis results, some interesting conclusions and helpful suggestions were obtained for the managers of the ports of Hong Kong and Kaohsiung to improve their port management.

An inventory positioning and location decision model based on centralized storage and lateral transshipment in multi-echelon supply chain

The two-echelon inventory system considered in this work is based on one single supplier, multiple distribution centers, and multiple retailers. In each echelon safety inventory is centralized stored in several centralized storage centers and lateral transshipment of safety stock is permitted between centralized storage site and non-centralized storage sites. The inventory positioning and location decision model developed focuses on safety stock cost, lateral transshipment cost, transportation cost, construction cost and shortage cost in multi-echelon supply chain. Numerical experiments show that: no matter whether in the echelon of distribution centers or retailers the factors which affect the selection from one single centralized storage center or multiple centralized storage centers are distance between distribution centers or retailers, unit transshipment cost and unit inventory carrying cost.

Efficient Heuristic Based Methods for Two-Stage Transshipment Problem

In this article, we propose efficient methods for solving two stage transshipment problems. Transshipment problem is the special case of Minimum cost flow problem in which arc capacities are infinite. We start by proposing a novel problem formulation for a two stage transshipment problem. Later, special structure of our problem formulation is utilized to devise two dual based heuristics solutions with computational complexity of O (n2), and O (n3) respectively. These methods are motivated by the methods developed by Sharma and Saxena [1], Sinha and Sharma [2]. Our methods differ in the initialization and the subsequent variation of the dual variables associated with the transshipment nodes along the shortest path. Lastly, a method is proposed to extract a very good primal solution from the given dual solutions with a computational complexity of O (n2). Efficacy of these methods is demonstrated by our numerical analysis on 200 random problems.

A Transshipment Model of Seven-Up Bottling Company, Benin Plant, Nigeria

This research work seeks to model the distribution of 50 cl Pepsi soft drink as a transhipment problem. The transshipment problem is an extension of the traditional transportation problem which takes into account a multi-phase transport system in which the flows of goods and services are taken through an intermediate point (transhipment points) between the origin and the destination with varying objective functions. The main focus in this research was to obtain the minimum cost of transporting 10,000 crates of the product from the Benin plant (source) through deports (transshipment points) to the Sapele-Warri region (sinks) where the product is demanded. Data collected were analyzed using TORA Windows Version 2.00 software. The analysis shows that the minimum cost of transporting the product can be achieved if the product is shipped directly from the source to the sink. This forms that basis for the conclusions and recommendations of the research.

A HUB FOR TRANSSHIPMENT

One of Dalian Port’s major targets is to push forward the containers traffic in Dalian or even Northeast China as well as become an important international transshipment hub in the region. The Dailian municipal government signed a framework agreement with the China Ocean Shipping (Group) Company (COSCO) on July 21, 2004. Two days later, the municipal government signed a co-operative

加油站补货管理系统中在途库存的实时转运策略

加油站补货管理系统中的在途库存实时转运问题需要考虑转运时间以及未来不确定的需求,且需要实时响应转运需求。针对该难题,以最大化剩余决策时段内整体收益为目标,提出一种结合需求预测模型和随机需求分布以分段衡量整体收益的方法,解决了加油站补货管理系统中在途库存的实时转运难题。首先,将剩余决策时段划分为两个时段。其次,基于需求预测模型量化第1个时段内的需求,以衡量该时段的利润总和,并确定第2个时段初站点的库存水平;采用随机分布衡量需求的不确定性,基于近似动态规划算法求解库存水平的值函数,以衡量第2个时段的利润总和;设计拟被转运走部分在途库存的站点的选择规则,缩小决策空间以提高策略的响应效率。最后,对比实验验证了本文方法产生的转运策略在不同站点规模和初始库存范围下的有效性,并得出管理启示。本研究可为加油站补货管理系统中在途库存的实时转运提供决策支持,对类似需同时考虑转运时间和未来需求的实时转运问题具有启发意义。

石油污染土壤微生物修复技术及机理研究进展

综述了环境微生物技术在石油污染土壤修复中的应用方法,介绍了人为干预提高石油降解微生物治理油污土壤的原位和异位修复技术和微生物去除石油组分的作用机理。针对微生物修复的研究热点多为石油降解微生物的选取及多种微生物的复合菌对石油组分的去除效果,但对微生物技术的实际应用和机理研究相对较少。提出了未来微生物技术修复石油污染土壤的研究和发展方向,包括特定材料对微生物的固定化、利用宏组学与示踪技术进一步明确微生物的降解机理和质粒拼接手段构建高效基因工程菌。

集装箱海铁联运运输组织优化研究综述

多式联运是集装箱运输组织的高级形态,而海铁联运作为两种运输批量最大的运输方式的组合,具有其他联运方式所无法比拟的规模与成本优势。近年来,随着中欧集装箱班列规模的不断扩大,我国海铁联运虽然得到了迅猛发展,但是与发达经济体20%~40%海铁联运占比相比较,我国占比不到3%还有巨大的增长空间。鉴于此,基于海铁联运运输组织优化的“软衔接”视角,从港站堆场资源配置协同、换装作业协同、班列开行方案优化三个维度对集装箱海铁联运相关研究进行梳理和评述,并提出潜在研究方向,以期对集装箱海铁联运的运输组织优化提供决策参考。

考虑中转的集装箱码头多资源集成调度

为高效利用码头资源,提高集装箱码头作业效率,以大型转运港为背景,针对码头资源分配的战术决策问题,考虑到船期表稳定性、船舶间集装箱转运流量、泊位调度和堆场分配的相互影响,基于码头主动管理策略,建立了以所有集装箱转运任务完成时间最小化为目标的码头多资源协同优化模型。在此基础上,设计了一种基于禁忌搜索的人工免疫算法对模型进行求解,通过六种不同规模的数值实验,以及与遗传算法和人工免疫算法的比较实验,验证了模型和算法的有效性。通过多情景案例分析,检验了协同调度模型的全面性和优越性,情景分析结果表明,综合决策模型最小可缩短4.33%的转运作业时间,最大可缩短20.19%,为集装箱码头多资源分配提供了有效的解决方法。

基于多目标优化的多码头转运港泊位资源分配研究

集装箱的水水中转是一种经济高效的水路运输模式,为有效降低水水中转下中转箱在大型转运枢纽港的码头间中转成本,提出了基于多目标优化的多码头转运港泊位资源分配方案。该方案考虑了船舶安全靠泊时间与距离以及中转箱与船舶的匹配关系等约束,建立了多目标混合整数规划模型,旨在最小化船舶在港时间成本与中转箱码头间运输成本;使用非支配排序遗传算法(NSGA-Ⅱ)对模型进行求解,得到了多组不同规模下的船舶靠泊与中转箱转运方案。研究表明:该算法能够得到多组帕累托前沿解,为港口运营商和船舶公司提供多个优化方案,以船舶在港时间成本的增长为代价,中转箱码头间中转运输成本呈减少的趋势;相较于基于最小时间成本的传统调度方案,提出的调度方案能够有效降低多码头下船舶靠泊的运营成本,同时在不确定情景下具有良好的鲁棒性;具体而言,在不同船舶规模下,能够减少作业总成本的38.25%~69.48%;以较小程度的船舶在港时间成本损失为代价,明显减少中转箱的码头间中转成本,为水水中转下的泊位分配和码头间运输集成优化提供参考。

考虑横向供应的多阶段装备维修器材供应优化方法研究

装备维修器材的精确、定量和快速供应是部队遂行作战、训练等任务的重要物质保证。针对多阶段装备维修器材供应问题,考虑多种器材供应方式,构建装备维修器材多级供应模式。为提升器材供应方案的全局最优性,将野战仓库选址、器材库存控制及运输车辆路径规划等关键问题融合为一类选址-库存-路径组合优化问题,以总成本最小为目标,考虑部队级仓库间的横向供应方式,构建混合整数线性规划模型。设计一种基于逻辑的Benders分解算法,将原问题分解为主问题和子问题,通过生成Benders切割迭代求解。通过示例分析证明:(1)本文所提出的LBBD算法能够有效降低问题复杂度,提升求解质量,LBBD算法得出的供应方案总成本比CPLEX求解器得出方案成本低41.62%;(2)考虑横向供应能够有效降低保障费用,考虑横向供应能够使总成本降低6.24%,同时,考虑横向供应可提高装备维修器材供应系统的灵活性。

一种水水中转比例高且可调的自动化集装箱码头交通分流工艺

为确保装卸作业安全,自动化集装箱码头设计的重点在于如何将港内自动化水平运输设备和外集卡交通流分离。水水中转是世界上许多集装箱枢纽港的主要集散方式。水水中转比例不同,码头海陆侧进出港箱量的比例随之不同,对水平运输系统的要求也不同。针对目前已建或在建自动化集装箱码头的交通分流工艺对水水中转比例适应性的局限性,提出了一种水水中转比例高且可调的自动化集装箱码头交通分流工艺,并对该工艺水水中转比例调整的适应性进行分析,可为类似自动化集装箱码头的规划建设提供参考。

青龙寺煤矿带式输送机转载点封闭微负压除尘技术研究

为了解决青龙寺煤矿带式输送机转载点粉尘问题,提出了封闭微负压除尘理论。首先对转载点封闭微负压空间模型进行了分析,确定了确保空间内保持微负压状态时排风量与诱导风量和挤占同体积空气量之间的关系;其次对诱导风流的计算开展研究,拟定了诱导风量计算方程,并结合青龙寺煤矿转载点实际数据,开展保持微负压状态时的最小排风量及控尘点保持最低控尘风速时所需排风量计算,经过对比确定了排风量不得小于153 m^(3)/min;最后根据计算结果,现场选取了KCS-180D除尘风机为主要除尘设备的除尘系统,转载点降尘效率达到90%以上,取得了理想效果。

基于FEM的某装卸过驳船卸船机基座结构设计

为论证卸船机基座结构形式的安全合理性,拓宽卸船机基座结构设计的思路和方法,以一艘44米装卸过驳船作为分析对象,采用有限元分析方法,首先建立包含卸船机基座结构的舱段模型,通过对主甲板与横纵强结构相交的高应力区域进行应力计算分析,根据结构应力分布特点提出若干种结构加强方案,可为该类船舶的卸船机基座结构设计提供参考。

基于差分进化算法的铝矾土转运船队规模优化研究

针对干散货船运输航线上船舶转运中的船队规模问题,以年度总租船成本最小为目标,考虑转运过程中的不确定需求、港口堆存限制和潮汐时间窗等约束,建立整数线性规划模型。以渤海湾地区进口铝矾土从烟台港转运至滨州套尔河港区的转运航线为例对模型进行应用和验证,并采用差分进化算法求解问题模型。结果表明:该转运航线上船舶每月航行13个简单航次;转运船队的规模受运价的影响最大;货主应选择提前转运货物以减轻堆存压力的同时保证租船成本最小。

基于不完全转运的民机可修备件库存优化研究

结合保障实际,为进一步优化航空公司备件库存策略及运营成本,研究多基地间允许相互调拨但不完全共享可修备件的单级保障系统库存优化问题。根据泊松分布函数及马尔可夫过程理论分别对系统和基地进行库存分析,在此基础上建立以综合保障率和各基地保障率为约束,以最小化系统总成本为目标的不完全转运备件库存优化模型。进一步构造迭代算法和粒子群算法进行优化求解。AnyLogic算例仿真及对关键参数进行敏感性分析的统计结果表明,在不同情况的最优配置策略下,对比优化方法和仿真计算得到的各基地保障率最大误差为0.06,系统总成本最大相对误差为0.31%,并能达到或十分接近于目标保障率要求。敏感性分析及误差分析表明所提模型及算法均可行有效。

航线联营下基于转运的飞机航线路径优化

为解决航空运输成本高,运输资源闲置、浪费多的问题,对航线联营下基于转运的飞机航线路径优化问题进行研究。基于货物转运问题,考虑联盟对运营的影响,引入航空联盟选择概率,确定转运前后航段运输的承运及托运问题,并考虑托运运输的衔接问题。由于航空网络中双机场容量限制,运行中全货机飞行时段及空域容量的限制,以总成本最小化为目标,建立了航线联营下基于转运的航线路径优化模型(T-AAAFRP)。设计了改进的遗传算法求解模型。通过实例分析,研究选址和路径优化问题。研究结果表明:设计的算法具有较高的收敛性;转运点数量变化的过程中,双机场城市总被选择作为转运点;需求量、飞机固定成本的变化对优化决策有较大影响;飞机载重量、联盟承运与托运的分摊系数、决策者风险偏好的变化对优化决策有较小影响;总体上转运点数量越多,所承担的总成本越小,使用的飞机数量越少。