A mathematical model of inter-terminal transportation

We present a novel integer programming model for analyzing inter-terminal transportation (ITT) in new and expanding sea ports. ITT is the movement of containers between terminals (sea, rail or otherwise) within a port. ITT represents a significant source of delay for containers being transshipped, which costs ports money and affects a port’s reputation. Our model assists ports in analyzing the impact of new infrastructure, the placement of terminals, and ITT vehicle investments. We provide analysis of ITT at two ports, the port of Hamburg, Germany and the Maasvlakte 1 & 2 area of the port of Rotterdam, The Netherlands, in which we solve a vehicle flow combined with a multi-commodity container flow on a congestion based time–space graph to optimality. We introduce a two-step solution procedure that computes a relaxation of the overall ITT problem in order to find solutions faster. Our graph contains special structures to model the long term loading and unloading of vehicles, and our model is general enough to model a number of important real-world aspects of ITT, such as traffic congestion, penalized late container delivery, multiple ITT transportation modes, and port infrastructure modifications. We show that our model can scale to real-world sizes and provide ports with important information for their long term decision making.     

A mixed integer and multiple objective programming model to analyze coal handling in New England

Mandated electric generation coal conversions in New England could place a severe strain on the coal handling and transportation facilities in New England ports. This paper presents an analytical scheme leading to the development of optimal plans for the reuse and redevelopment of marine transport networks in New England. Utilizing the port inventory that provides information on existing coal handling facilities and the capability of the ports to increase capacity of existing facilities or locating new facilities, a mathematical programming model is used to determine the optimal capacity, placement and railrod and marine interface of coal handling facilities within and between the New England ports and converting power plants.Initially a mixed integer programming model with a least cost objective is formulated. It is then expanded to a multiobjective programming problem in order to provide information to the port planners and decision makers on the tradeoffs between the costs and temporal efficiency of coal transporation and handling for various locational configurations.     

21世纪海上丝绸之路沿线港口体系演化研究——基于Logistics、Lotka-Volterra模型

港口体系演化研究揭示21世纪海上丝绸之路沿线港口的发展规律,为我国相关企业海外港口投资提供决策支持,进而为我国“海上丝绸之路”战略的具体实施提供理论依据。本文利用生态种群演化相关理论,选取东南亚港口为数据样本来研究港口体系演化过程,研究发现港口规模演化趋势符合Logistics演化规律,2008年时增长速度达到峰值,2013年海上丝绸之路沿线港口体系进入衰退期,2030年左右港口体系规模将达到极限值;建立双种群增长的Lotka-Volterra模型和多种群增长模型研究新加坡港、巴生港、柔佛、槟城、丹戎帕拉帕斯的相互关系和演化趋势,提出我国在与这些港口合作时需要依据这种关系和演化趋势去统筹协调,才能达到效益最大化。     

基于低碳环保因素的“前港后厂”钢铁产成品运输网络优化

中国大部分钢铁企业深居内陆,出口钢材需远距离运输到港口,再通过海运发往世界各地,故建立港口与钢铁企业的合作关系将尤为重要。与铁路、水路运输相比,公路运输单位换算周转量的碳排放量更高。但中国内陆运输多采用公路运输,这将加剧大气污染。本文提出基于“前港后厂”联运的钢铁产成品运输问题,以加强港口与钢铁企业的合作。为降低运营成本和碳排放量,建立以碳排放成本、运输成本、仓储成本及时间窗惩罚成本最小为目标的钢铁产成品运输网络优化模型;并设计融合和声搜索的环形拓扑结构PSO算法进行求解;最后对仓储成本进行灵敏度分析,以探究其对“前港后厂”模式的影响。结果表明,“前港后厂”模式不仅能有效降低运输网络的总成本和碳排放量,且合理的仓储成本更能加强港口和钢铁企业间的紧密性。     

Chapter 11 Simulation studies of efficiency,returns to scale and misspecification with nonlinear functions in DEA

Using statistically designed experiments, 12,500 observations are generated from a 4-pieced Cobb-Douglas function exhibiting increasing and decreasing returns to scale in its different pieces. Performances of DEA and frontier regressions represented by COLS (Corrected Ordinary Least Squares) are compared at sample sizes ofn=50, 100, 150 and 200. Statistical consistency is exhibited, with performances improving as sample sizes increase. Both DEA and COLS generally give good results at all sample sizes. In evaluating efficiency, DEA generally shows superior performance, with BCC models being best (except at corner points), followed by the CCR model and then by COLS, with log-linear regressions performing better than their translog counterparts at almost all sample sizes. Because of the need to consider locally varying behavior, only the CCR and translog models are used for returns to scale, with CCR being the better performer. An additional set of 7,500 observations were generated under conditions that made it possible to compare efficiency evaluations in the presence of collinearity and with model misspecification in the form of added and omitted variables. Results were similar to the larger experiment: the BCC model is the best performer. However, COLS exhibited surprisingly good performances — which suggests that COLS may have previously unidentified robustness properties — while the CCR model is the poorest performer when one of the variables used to generate the observations is omitted.     

考虑横纵向一体化的港航联盟的收益模型

随着港航业竞争的加剧,港口间的联盟与合作、港口与航运企业纵向一体化不断发展。尤其是,航运企业以收购或投资模式参与港口间的资源整合,形成了更为复杂的港航混合联盟。针对港口间的资源整合与竞争、航运企业与港口一体化等因素,构建港航混合联盟模式的收益模型,对比分析在区域港口竞争模式和港航混合联盟模式下港口和航运企业的收益变化,揭示地理位置、内陆运输成本、航运企业投资效果等因素的作用。结果表明,港航混合联盟模式能够实现整合港口和航运企业的双赢。同时,当港口与内陆的集疏运基础设施薄弱、航运企业的影响力较大时,非合作港口也会受益,此时港航横纵向混合联盟模式有利于推动整个区域港口经济的发展。     

Tandem queues in bulk port operations

The study is motivated by the operations at the bulk material handling port of Kamsar in Guinea. Bauxite ore is brought to port to load vessels that arrive on a semischeduled basis. Vessels go through several stages of delays due to sailing, tide and due to time in a waiting berth before and after they are loaded. We propose bounds and an approximation for a modified port time which is a significant measure of performance in bulkmaterial port operations.     

Combined Sea and Land Transportation

An important problem today in the field of transportation is the standardization of the cargo, e.g. by using containers, and the design of the handling and transportation equipment for the specific cargo to be transported.The paper presents a method for determining the transportation system with emphasis on sea transport. Thus the cargo is to be transported by sea from the factory to customers spread over a large region, e.g. Europe. The problem is to select the ports of call, the quantities to be delivered at the ports, as well as the size and type of vessel.This problem resembles the warehouse location problem (the location of ports) but requires in addition the determination of ship size, type of ship and whether one or more ports should be called at on each journey with a single ship. A discussion is also presented as to the possibility of considering randomness in the system with respect to customer demand and weather conditions.The method used resembles that suggested by Baumol and Wolfe for the ware-house location problem. A concave function of the quantities delivered at each port is derived and this is then shown to converge to a local optimum.An example is solved to illustrate the method.     

Cooperative game theory approach to allocating benefits of horizontal cooperation

Logistics costs in general, and transportation costs in particular, represent a large fraction of the operating costs of many companies. One way to try to reduce these costs is through horizontal cooperation among shippers. Thus, when the transportation needs of two or more companies are merged, their collective transportation requirements can be met at lower cost. The attainable cost savings are due to economies of scale, which translate into cheaper rates due to increased negotiation power, use of larger vehicles and bundling of shipments. In this paper, a linear model is presented and used to study the cost savings that different companies may achieve when they merge their transportation requirements. On the one hand, solving this optimization model for different collaboration scenarios allows testing and quantifying the synergies among different potential partners, thus identifying the most profitable collaboration opportunities. On the other, the problem of allocating the joint cost savings of the cooperation is tackled using cooperative game theory. The proposed approach is illustrated with an example in which different cooperative game solution concepts are compared. Extensive numerical experiments have also been carried out to gain insight into the properties of the corresponding cost savings game and the behavior of the different solution concepts.     

海运服务链中的运力定价和空箱调运责任研究

本文研究了单个承运商和两个货运代理在双向港口间提供往返货运服务的航运服务链。由于港口间货运需求的内在不平衡,货运公司在多港口间的空箱调运会产生巨大的空箱调运费用。分别构建了承运商承担和承运商与货运代理共同承担空箱调运的数学模型,通过数学模型和数值算例分析了不同市场条件下的空箱调运责任和运力定价策略。研究发现承运商和货运代理是否采用定价策略来平衡需求取决于双向港口间货运市场的潜在需求差异。同时,承运商与货运代理的空箱调运分摊为非此即彼策略,当空箱调运成本大于某阈值时,承运商独自承担空箱调运责任;反之,货运代理承担空箱调运责任。而且货运代理承担模式增加整个海运链的利润,但进一步加剧空箱的不平衡状况。     

Location of speed-up subnetworks

Let a network with edge weights, a set of point-to-point transportation requests and a factor \(\alpha \) be given. Our goal is to design a subnetwork of given length along which transportation costs are reduced by \(\alpha \) . This reduces the costs of the network traffic which will choose to use edges of the new subnetwork if this is the more efficient option. Our goal is to design the subnetwork in such a way that the worst-case cost of all routing requests is minimized. The problem occurs in many applications, among others in transportation networks, in backbone, information, communication, or electricity networks. We classify the problem according to the types of the given network and of the network to be established. We are able to clarify the complexity status in all considered cases. It turns out that finding an optimal subtree in a tree already is NP-hard. We therefore further investigate this case and propose results and a solution approach.     

“冰上丝绸之路”货物吸引的中国沿海港口空间分异及类型识别

通过构建港口货物吸引潜力模型,预测“冰上丝绸之路”建设完成后,中国沿海港口体系针对中国-西北欧海运贸易的货运空间格局并识别货运空间类型。结果显示:在空间格局方面,吸引潜力分布呈由北向南逐次递减趋势;液化天然气、煤炭、铁矿石、木材和潜力总值具有显著的空间正相关性,石油和集装箱在空间上表现为随机分布模式;环渤海和长三角已具有一定的港口层级结构特征,东南沿海、珠三角和西南沿海低值集聚特征较明显。在货运空间类型方面,港口体系结构的重心在北部港口地区,环渤海大型港口的综合性货流聚集能力要强于其他地区,沿海港口基本符合货运规模越大,其综合货运等级越高的趋势。     

Antichain sequences

For any finite partially ordered set S we display a dual transportation system of linear inequalities, and a bijection A(x) from the maximal integer-valued solutions x of this system onto the maximal sequences of k antichains in S. This provides a simple translation to a dual transportation problem of the problem: find a maximum weight union of k antichains.Research supported by the Natural Sciences and Engineering Research of Canada.     

Net subgroups of Chevalley groups. II. Gauss decomposition

This paper is a continuation of RZhMat 1980, 5A439, where there was introduced the subgroup () of the Chevalley group G(,R) of type over a commutative ring R that corresponds to a net , i.e., to a set =(),, of ideals of R such that ₊ whenever ,,+ . It is proved that if the ring R is semilocal, then () coincides with the group ₀ considered earlier in RZhMat 1976, 10A151; 1977, 10A301; 1978, 6A476. For this purpose there is constructed a decomposition of () into a product of unipotent subgroups and a torus. Analogous results are obtained for sub-radical nets over an arbitrary commutative ring.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 114, pp. 62–76, 1982.In conclusion, the authors would like to thank Z. I. Borevich for his interest in this paper.     

Delay Embeddings for Forced Systems. II. Stochastic Forcing

Takens Embedding Theorem forms the basis of virtually all approaches to the analysis of time series generated by nonlinear deterministic dynamical systems. It typically allows us to reconstruct an unknown dynamical system which gave rise to a given observed scalar time series simply by constructing a new state space out of successive values of the time series. This provides the theoretical foundation for many popular techniques, including those for the measurement of fractal dimensions and Liapunov exponents, for the prediction of future behaviour, for noise reduction and signal separation, and most recently for control and targeting. Current versions of Takens Theorem assume that the underlying system is autonomous (and noise-free). Unfortunately this is not the case for many real systems. In a previous paper, one of us showed how to extend Takens Theorem to deterministically forced systems. Here, we use similar techniques to prove a number of delay embedding theorems for arbitrarily and stochastically forced systems. As a special case, we obtain embedding results for Iterated Functions Systems, and we also briefly consider noisy observations.     

Transaction cost analysis of supply chain logistics services: firm-based <Emphasis Type="Italic">versus</Emphasis> port-focal

With the overwhelming findings that systemic risk dominates idiosyncratic risk in individual firms along a supply chain or in an industrial sector, and noting the fact that supply chain literature so far has been firm-based, it is critical to analyse inter-firm transactions and related risks which have largely been omitted from current supply chain research. To advance along this critical dimension, we develop a transaction cost frontier model that allows inter-firm transaction facilities in terms of a port-focal supply chain modelling framework. The key findings are as follows. (1) Environment heterogeneity is a characteristic transaction attribute, and logistics efficiency is critically dependent on both intra-firm asset specificity (Williamson, 2002) and inter-firm environment heterogeneity when ports are considered as transaction facilities. Port logistics demonstrates that horizontal integration (as opposed to vertical integration) becomes more cost effective as environment heterogeneity increases, given the same degree of asset specificity among individual ports. (2) An adaptive advantage (eg, transaction efficiency) is identified and characterized through the port-focal industrialization of supply chains, and is found to be an explanatory cause for the geographically concentrated horizontal specialization and differentiation, as increasingly observed in practice. Logistics industrialization will bring about the growth of port-focal urbanization.     

A nonlinear bilevel model for analysis of electric utility demand-side planning issues

An application of bilevel programming in the electric utility industry is presented. The model is nonlinear and is used to analyze various economic issues that affect electric utility planning. The electric utility at the upper level of the model seeks to minimize costs or maximize benefits while controlling electric rates and subsidizing energy conservation programs. Customers at the lower level attempt to maximize their net benefit by consuming electricity and investing in conservation. This model considers factors such as free riders and the rebound effect which affect the net benefits of utility resource plans but are ignored by most planning models. The model's solutions shed light on utility issues including whether there can be a practical difference between various objectives, including minimizing cost (least cost planning) and maximizing net social welfare (value based planning).     

Application of a quantification SWOT analytical method

In this paper we present a Quantified SWOT (Strengths, Weaknesses, Opportunities and Threats) analytical method which provides more detailed and quantified data for SWOT analysis. The Quantified SWOT analytical method adopts the concept of Multiple-Attribute Decision Making (MADM), which uses a multi-layer scheme to simplify complicated problems, and thus is able to perform SWOT analysis on several enterprises simultaneously. Container ports in East Asia are taken as a case study in this paper. Quantified SWOT analysis is used to assess the competing strength of each port and then suggest an adoptable competing strategy for each.