| The emergence and development of logistics industry stem from social division of labor and economic development. Generally speaking, traditional logistics activities are scatters in different kinds of economy departments, enterprises and its functional departments. And along with the rapid development of economy, the promotion of technology level and the increasing of proceeding of industrialization, tremendous producing and consuming render logistics scale in the economy is much huge and complicated. The traditional and disperse activities cannot adapt to the economic demand any more. High cost and low efficiency of the traditional one have played as a role having a negative effect on performance of economy and social reproduction, thus logistics is widely treated as "the dark continent in the economy".With the development of continuous globalization, promoted science technology and specialized division in labor, a revolution integrating various logistics functions with essences sweeps over the world. Such a kind of resource integration and unify shift logistics to the whole interconnected and farm-out industry chain rather than let it be confined to one extent of some enterprise. A resultant socialized system keeping supply chain management as a central task appeared due to this kind of integration, logistics activities thus gradually become the specialized activities born by independent economic organization, and those activities are independent of producing, trading and consuming.There are various reasons for enterprises to establish logistics center. In the second half of the twentieth century, because of the improvement of science technology and the development of economy, scale of exploitation and utilization of natural resource expanded rapidly and transport volume of freight increased significantly, number of transport services thus soared, while enterprises are faced with pressures from shorter delivery cycle, higher quality of commodity, lower cost and better service, market competition hence increasingly fierce. Various forms of retail trades, such as chain business, specialty store and non store sales, emerge as the times require, and this provides a diversification channel for commodity circulation, improving structure changes in producing and marketing, and it also prompts high efficiency and reshuffles during the circulation step. As a result, logistics distribution has a opportunity to develop and the traditional conceptions encircled with warehouse are abandoned. As a logistics node, development of warehouses rapidly changes from single reservation to multifunction including taking goods, sorting, loading, processing and distributing. Other kinds of logistics nodes in airport, harbor, train station and bus station are expanding their own functions, and most of them evolved into the modern distribution center little by little. Establishment of logistics center mainly bases on those factors:The urgent requirement of curtailing logistics cost, fierce increasing volume of commodities circulation, magnitude revolution in transport mode-the formation of multimodal transport and comprehensive transport system, impetus of science technology, appearance of new trade form and perfecting needs of cities’ function.As one node in logistics network, logistics distribution center accommodates itself to the development of economy, and with its improvement in centralization degree and function, ameliorations from distribution center disentangle warehouses and station yards from their original limitations, expanding various functions. The modem distribution center congregates nearly all functions that logistics trades have, thus it has a variety of circulation form and operation systems with logistics function. Modern distribution center also manages works like purchasing, stocking, reserving, sorting and distributing scientifically and standardly by advanced technology and modern information network so that proceeding of commodities can be high efficient, coordinating and ordered.Logistics center having multi-function, advanced scale, strength of aggregation and segregation and big service coverage plays absolutely crucial role in the development of regional economy, and examples of its functions are shown as follows:optimizations of regional logistics constitution, refinements of market system, promotions of economy rank of city and boosts of sustainable development of city.Nowadays, much more attention than ever before has been paid to modem logistics, which is named as the third resource of profit. Logistics is one of the most significant part of modern industry. In the modernization production, it is hard to evidently improve productivity and efficiency of facility in the workshop. The logistics system, however, reverses tremendous potential economic benefits.Logistics centers facilitate implementations of scale of operation and enhance efficiency. Characters of logistics centers can be best epitomized by scale of operation in that logistics centers have great deal of circulation channels and flux and they adopt assemble line method to integrate circulation volume of thousand families into a body so that scale of circulation and its efficiency can be obtained.Logistics centers is instrumental in optimizing resource configuration and improving competitive strength. Because of influences of traditional management theory, majority of old enterprises usually adopt operation modes like small and comprehensive style or big and complete one, and this reflects that a series of equipment and facilities from production to transportation are possessed in these concerns. In the era of rapid development of technology, of increasing drastic competition, of frequently varied demand of clients, the management mode commanding whole procedures which comprises purchasing, manufacturing, distributing and selling, however, does not have attractions any more, and it by contrast exposes several defections:the traditional mode increases investment burden of enterprises, the mode makes concerns undertake ventures of losing market opportunity and some subsidiaries are not similar with business the headquarters assigned to them and this may provokes vulnerable complexions in the competition. Enterprise does not have to appropriate funds to construct warehouse and logistics installation and training logistics staffs as long as it outsources non-core business to logistics centers, then concern could avail itself of finite resources to strengthen its specialty business and competitive strength, and the concern will be one of outstanding competitors in the trade. Meanwhile, usage of land resources and facilities are significantly heightened, and this decreases costs of hardware, software, relieving fund occupation in the circulation and manufacture concerns and advancing logistics techniques and management level.Logistics centers has great deal to do with output elasticity and tight combination of consumption and production. In condition of markets economy, prominent requirement properties of variety, small batch and vouge have been highlighted, which demand that modes of large scale production must have flexibilities in the producing system, and thus products could be transported to markets. The implementation of flexible product system hinges on instant provision of market information. Logistics centers ought to tightly connect products and market demands by collecting the up to date market information from suppliers, manufacturers and sellers.The establish of logistics center relieves traffic pressure and improves development of the urban. The increasing development of economy enriches supplements of merchandise, and under this background, types of consumption demand are varied and volume of logistics explored drastically. The enlargement of logistics volume not only requires unobstructed channels to upgrade availability of capacity of logistic facilities, but also needs adjustments of logistics spacial distribution to control traffic demand. According to the reasonable planning of urban logistics center, logistics enterprise can be efficiently arranged and troubles like traffic congestions can be solved. Plus, the reasonable planning of urban logistics center avoid random distribution of various logistics facilities and this to some extent aids adjustment of structures of urban land use and avoid destructions and contaminations produced by chaotic configuration of the facility, the environmental conversation and sustainable development of city, therefore, can be obtained. Logistics center is helpful to the development of multimodal and combined transportation. With the rapid development of economic globalization, the emergence of multinational corporations significantly strengthen the adjustment of economy structures and transference of industries all around the world. This embodies in the activities of large scale of transnational producing, operating and selling, which propel not only the internationalized manufacture but also the development of international trade. In order to angle for advantages in competition, curtailing cost continually is important for manufacturers, and providing comprehensive services for demanders generates convergence of the world’s means of production market, making demands of whole consumers unified. The concentration of resource market and the convergence of product one impulse rapid development of intercontinental and multinational container transportation, and this needs higher requirement of its service level.Generally, logistics centers with large scales are located at conjunctive points between different transport modes:highway, railway, harbor and airport, and it is helpful for the development of multinational transport like highway-railway, sea-land and land-air. The using of multinational transport in the logistics center having large scales curtails logistics operation time by decreasing procedures of loading and storing and heightens logistics service levels. In addition, the stable development of combined transport just can be realized in the field like container system by the old restrictions and this discourages combined transportations for blended and scattered cargoes. While the establishment of logistics center expends object of combined transport by synthesizing artery delivering between logistics centers and corresponding distribution activities.The establishment of logistics center propels modernization logistics industries and fulfills clients demands. Because of huge logistics volume in logistics centers, adoptions of advanced science technologies and facilities are necessary. For example, the improvement of modernization level in logistics operation can be realized by the using of tiered warehouse, automatic sorting system and electronic distribution system, and clients’demands thus are satisfied by available services in ordering, checking, liquidating and unconditional refunding.As what has been represented, logistics center has a great deal to do with circulation of commodities in the way that all logistics activities, such as transportation, reservation, handling operation, distribution, order and information processing, are in the charge of it. And the usage of distribution center is instrumental in promoting storage turnover rate and circulation of commodities and in decreasing logistics cost. Thus it is of overriding importance for logistics center to have a appropriate location. And for this reason, an increasing number of logistics centers appeared in the developed countries.Taking Europe as an example, which has a larger population and a higher combined Gross Domestic Product (GDP) than the U.S., yet it has4.5times less Class-A logistics space. In this context, the reconfiguration of the European supply chain and the rise of e-commerce means there is significant development potential for modern, efficient distribution facilities across the region. The questions facing developers, owners, managers, and their customers, are:"Where are the most strategic logistics locations in Europe, and why?"The answers to these questions are essential for making well-informed investment and development decisions. Prologis, inc., the leading owner, operator and developer of industrial real estate, has partnered with Eyefortrans-port (EFT) to explore industry perceptions on the most desirable logistics locations around Europe, and to quantify the criteria which influence site selection. As well as demand, supply is equally important to investors since markets with tight supply and higher entry barriers generally outperform markets with weaker demand/supply dynamics. The conclusion of exploration is that there is an undersupply of Class-A logistics space in Europe, and the reconfiguration of the European supply chain and the rise of e-commerce means there is significant development potential for modern, efficient distribution facilities across the region. Thus lit is essential for logistics companies to constantly optimize their distribution strategies to ensure high service levels for minimal costs.Location plays a definitely important role in the whole logistics system, and it belongs to issues of logistics management on strategy level. Policy of location of distribution facility aims at determining numbers, position and formulas of facilities being allocated. And those facilities mainly denote nodes in the logistics system, for instance, manufactures, suppliers, warehouses, distribution centers, retailers, etc..As far as single enterprise is concerned, it determined structures of the whole logistics system, and by contrast, programs of the system will have effect on location policies. Hence location has a tight relationships with storage and transport cost. Volume and cost of storage usually advanced along with increased number of facilities in the logistics system. Consequently, combining numbers of facilities and enlarging their scales are treated as measures curtailing storage cost. And that is part of the reason why logistics enterprises build great deal of distribution centers to realize the large scale of distribution.While relationship between number of facilities and transport cost is different from establishment quantity and storage cost. With number of facilities increased (e.g. number of distribution center advanced), length and cost of transportation may be decreased. The transport cost, however, will bounce up when number of facilities expanded to a critical extent. This is because the quantities of orders are so small that frequency of transport raises. So determining number of facilities rationally is also one of the main targets in location programming.Before having studies on logistics center location, conception about logistics supposed to be clear in the article. Conceptions of logistics were formed in developed countries like America and Japan, and with the increasing reinforcements of international interconnections and communications, concepts of logistics was introduced into other countries, now it is widely used as conception of economy. Because of the differences in perspective of the observation, in different countries even among different organizations of a country, however, interpretations on conception of logistics are various, and a resultant variety of theoretical definitions appeared, which have been recited in the article. And it also summarizes the conception of logistics.In order to give a feasible location planning for logistics center, relative factors about logistics center location are illustrated in the article. As far as impact factors are concerned, locating logistics center is a planning course which is affected by comprehensive factors, and those factors can be proximately divided into two groups:external factor and internal one. The former includes factors deriving from macro politics, economy, environment, infrastructure and competitors. And the later comprises factors like development strategies of enterprises and properties of productions, techniques and services. In the act of planning location of logistics centers, various kinds of factors, therefore, ought to be comprehensively concerned. Factors having an effect on location of logistics centers will be analyzed in the article one by one. And here the article mainly introduces external factors about locating planning.Principles and notes are also needed in logistics location, that is because logistics center is regarded as an essential node in the act of organizing social logistics activities, and unlike management that especially deals with socialized commodities production, the operation mode of logistics center is characterized by centralized activities like congregating various commodities from manufacturers, assorting and distributing and it aims at realizing economical scale of logistics activities and curtailing whole logistics cost significantly. Thus with impacts including distribution of merchandise resource, demand status and natural conditions, different kinds of planning formula of logistics center in the same region may generate big difference in operation cost of logistics system. How to setting up layout of logistics center to minimize logistics cost of whole system and to further service efficiency of clients and society have been a primary issue planner withed with.According to introduction and illustration of importance, principles and notes about logistics center location. Logistics center location model basing on distribution cost is proposed in the article to deal with location problems having geographical interdiction. Before that, relative theories and models in logistics center location are grossly depicted.Researches of models basing on function and cost in logistics center location field have been lasted for sixty years. And now a variety systems of models and theories are formed, they can be roughly divided as following:continuous models, discrete models and network models. The theory of continuous model deems that location to be determined can be treated as a facet and other factors such as structures are irrespective, thus the number of alternative locations is infinite. Because of continuity of the model, generally it can be efficiently analyzed. The representative algorithms of such kind of models are gravity method and crossing median method. And one prototype of application is preliminary logistics center location of enterprise; the conception of discrete model is that object location is a set of discrete alternative locations. Because the number of alternative locations is usually finite or even exiguous, such type of model is feasible. The cost of data collection and computation, however, is exorbitant. Actual distance can be used in the object function and restraint condition of model, and it also includes complex areas having barriers and infeasible locations.Logistics center location is one of the most important logistics plannings, and it has attracted much more attention due to its complexity and function. Hance specific and objective formula is needed before establishing logistics center. Location planning, however, is one of integral elements. What is more, impact factors in different kind of logistics center location are various and they are diverse in logistics operation performance. If blind imitation is committed in location, hardly could logistics centers be established economically. That is akin to saying that location methods which is feasible in non-geographical interdiction paradigm could not be introduced into geographical interdiction cases due to their differences in computation of linear distance.The article introduces continuous model and discrete one and concludes defections of current methods and theories. Traditional location models generally have slack contacts with realistic cases, that is, they are lack of feasibilities during applying. And then it discusses location modes with geographical interdiction, and then gives corresponding model for single logistics center and multi logistics centers.For the location model of single logistics center, realistic geographical condition of locations should be concerned, and thus location issue with geographical interdiction is proposed in the article. The article adopts modified distance function which derives minimum distance. And by the analysis of modified distance function, non-convexity and non-continuity of object function in whole convex region can be obtained, and then it makes the method applicable and feasible. The proposition of theories like approximate searching and minimum effective path method effectively give solution of single location models in geographical interdiction conditions. In order to facilitate study, the article combining actual geographical conditions modified distance function. The model of multi-logistics centers location is also given and discussed in geographical interdiction condition. And the article mainly focuses on solving single paradigm issue by genetic algorithm.The author introduces theories and procedures of genetic algorithm, and then gives a numerical example about single logistics center location having geographical interdiction, which will be solve be the algorithm to prove the correctness of model. The example includes one river-the geographical interdiction-having two bridges on it and seven distribution nodes. By the genetic algorithm computation, finally the coordinate of logistics center is obtained And thus the feasibility and correctness of the model is proved. |
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