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.

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.

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.

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.

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.

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.

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

Joint inventory and transshipment decisions with consumer behavioral heterogeneity

Transshipment is an effective method for reducing mismatches between supply and demand among retailers.Consumers attempting to purchase out-of-stock items may wait for transshipment,purchase at another store,or choose not to buy.In this paper,the consumer behavioral heterogeneity is characterized using the transshipment request rate and consumer switching rate.It affects the replenishment and transshipment decisions,as well as the system profits.The inventory replenishment and transshipment decisions are studied in both centralized and decentralized two-location inventory systems with consumer behavioral heterogeneity.We characterize optimal replenishment decisions in a centralized system,prove the existence of a unique Nash equilibrium in a decentralized system with a specific demand distribution,and determine the coordinating transshipment price for some decentralized systems.In numerical studies,the performance of various systems is analyzed for consumers with identical(symmetric)or differing(asymmetric)behavior between retailers.For scenarios with symmetric consumers,a higher transshipment request rate and consumer switching rate resulted in increased total profit in all systems.For scenarios with asymmetric consumers,the retailer with the higher consumer switching rate should reduce ordering in a centralized system but increase ordering in a decentralized system.Moreover,the retailer with the higher transshipment request rate reduces ordering to increase profit,whereas the other retailer increases order quantity yet earns less profit.

E-Shop Transshipment Selection Evaluation Based on Cloud Model

In e-commerce, a critical problem is how to transship the products between different e-shops to lessen the risk of out of stock, especially in network shopping mall of China. Most of importance is how to select the optimal one in the waiting list of e-shops to make the transshipment economical. However, many factors that influence the effect of transshipment are uncertain and fuzzy, such as customer demand, product price and inventory level. Based on the cloud model theory, a novel method for evaluation of e-shop transshipment selection in the same network shopping mall is proposed to solve the problem. The factors that influence the transshipment effect are discussed in detail. An example of selecting the optimal e-shop to transship products to the out of stock e-shop is given on the basis of the steps of our evaluation calculation. Finally, the result shows that it can effectively optimize transshipment in online shopping economically.

Multi-Echelon Inventory Model with Emergency Lateral Transshipments

In multi-echelon inventory systems, since neighboring retailers are located at shorter distances than the supplier, a retailer may seek stock from them when it is out of stock, that is, emergency lateral transshipments between retailers are commonly practiced to provide improved order fill rate. In this paper, we develop a continuous review multi-echelon model for consumable products when emergency lateral transshipments between retailers are allowed. Approximations are derived for the expected level of cost and order fill rate of retailers. Simulations conducted to test the validity of the approximate analytical model indi-cate that it performs very well in the cases where fairly high service levels are required. Numerical examples are also presented to illustrate the effects of emergency lateral transshipments on the performance criteria of inventory systems. The results indicate that emergency lateral transshipments will lead to a significant in-crease in the retailer order fail rate and this initiative is most suitable for items with a high penalty cost, or where lost sales are likely.

Synthesis of indirect work exchange networks considering both isothermal and adiabatic process together with exergy analysis

In this paper, an efficient methodology for synthesizing the indirect work exchange networks(WEN) considering isothermal process and adiabatic process respectively based on transshipment model is first proposed. In contrast with superstructure method, the transshipment model is easier to obtain the minimum utility consumption taken as the objective function and more convenient for us to attain the optimal network configuration for further minimizing the number of units. Different from division of temperature intervals in heat exchange networks,different pressure intervals are gained according to the maximum compression/expansion ratio in consideration of operating principles of indirect work exchangers and the characteristics of no pressure constraints for stream matches. The presented approach for WEN synthesis is a linear programming model applied to the isothermal process, but for indirect work exchange networks with adiabatic process, a nonlinear programming model needs establishing. Additionally, temperatures should be regarded as decision variables limited to the range between inlet and outlet temperatures in each sub-network. The constructed transshipment model can be solved first to get the minimum utility consumption and further to determine the minimum number of units by merging the adjacent pressure intervals on the basis of the proposed merging methods, which is proved to be effective through exergy analysis at the level of units structures. Finally, two cases are calculated to confirm it is dramatically feasible and effective that the optimal WEN configuration can be gained by the proposed method.

Applying Network Flow Optimization Techniques to Improve Relief Goods Transport Strategies under Emergency Situation

Given the seriously damaged emergency situation occurring after a large-scale natural disaster, a critical and important problem that needs to be solved urgently is how to distribute the necessary relief goods, such as drinking water, food, and medicine, to the damaged area and how to transport them corresponding to the actual supply and demand situation as quickly as possible. The existing infrastructure, such as traffic roads, bridges, buildings, and other facilities, may suffer from severe damage. Assuming uncertainty related with each road segment’s availability, we formulate a transshipment network flow optimization problem under various types of uncertain situations. In order to express the uncertainty regarding the availability of each road segment, we apply the Monte Carlo simulation technique to generate random networks following certain probability distribution conditions. Then, we solve the model to obtain an optimal transport strategy for the relief goods. Thus, we try to implement a necessary and desirable response strategy for managing emergency cases caused by, for example, various natural disasters. Our modeling approach was then applied to the actual road network in Sumatra Island in Indonesia in 2009, when a disastrous earthquake occurred to develop effective and efficient public policies for emergency situations.

Dual Based Procedures for Un-Capacitated Minimum Cost Flow Problem

In this article, we devise two dual based methods for obtaining very good solution to a single stage un-capacitated minimum cost flow problem. These methods are an improvement to the methods already developed by Sharma and Saxena [1]. We further develop a method to extract a very good primal solution from a given dual solution. We later demonstrate the efficacies and the significance of these methods on 150 random problems.

The status quo and prospect of transfer and shift in patients receiving hemodialysis in China

Hemodialysis is the main alternative therapy for patients with end-stage renal disease;most of the hemodialysis centers in China are not designed together with the inpatient ward.During the hospitalization period,hemodialysis patients often move back and forth between wards and hemodialysis rooms because of the treatment needed.Hemodialysis patients are a special group of hospitalized patients,most of them are elderly patients.The overall basic diseases of the patients vary very much,and the cause of the disease is complex.Moreover,the chronic inflammation progresses slowly,and immune function declines.Some of the patient are seriously ill or even hav organ failure.All these factors affect the patients in general.Therefore,the transfer safety of patients during hospitalization is facing great challenges.The researchers reviewed the status of transshipment research in Chinese hemodialysis patients and laid the foundation for the research and development of related handover tools and perfect handover mode in the future.

The Determination of Optimal Routes of an Undirected Network

In this research paper, a routing problem of undirected networks has been solved. The problem was to determine the optimal routes of a telecommunication network. A heuristic approach has been adopted,due to the specific uature of the problem.The problem is only concerned withdistant(remote) nodes of the network which are indirectly linked through a single intermediate node.To determine the optimal routes,the devised heuristic has been coded in FORTRAN language. Forthe validation of developed heuristic,it has been implemented on two sample networks. Finally, ithas been applied to the actual(gived) network. The achieved results have proved its application insepcific networking problem. It can also enhance the effective utilization of available resources.

A Proposed Benchmark to Evaluate Investment in Maritime Hub Ports

This paper concerns in studying the evaluation of investment in sea hub ports, in terms of investment＇s real cost, types of investments, their aims, the direct and indirect effects of these investments, and the various methods used to assess the expected returns from such projects, in order to propose a criterion for investment in sea hub ports. Through divining methodological framework into three sections： the first one covers the topic of investment in general, its types, purposes, and its determinants; While the second section covers the different definitions of ports and types of investment projects in them, their nature, purposes and effects; Section three concentrates on the appropriateness of the methods used to evaluate sea port project, concluding a benchmark formula to be used in evaluating maritime hub port investment projects.