Purchasing Policy of New Containers Considering the Random Returns of Previously Issued Containers

A number of organizations sell products in containers that can be reused. The time from issue to return of an individual container is usually not known with certainty and there is a chance that the container is never returned (because of loss or irrepairable damage). Consequently, even under a level demand pattern new containers must be acquired from time to time. In this paper a purchasing policy of these new containers is determined for a finite time horizon so as to minimize the total purchasing and expected carrying costs under a prescribed service level. The associated stochastic model is reduced to a deterministic, dynamic lot-sizing problem with possible occurrence of negative net demand (demand minus return). A transformation into the usual nonnegative demand case allows us to apply well-known deterministic lot-sizing procedures to obtain the solution.     

A Statistical Methodology for the Analysis of the Life-Cycle of Reusable Containers

The effectiveness of recycling reusable containers as a means of spreading container costs depends on a knowledge of container life-cycle characteristics expressed through parameters such as trip-page, trip duration, loss rate, and expected useful life. Most existing estimation methods in industry are based on static ratios of inventory records. This paper describes, with numerical examples, a rigorous approach for data analysis and modeling which yields the needed parameters through a systematic examination of inherent statistical properties in routinely available data on container issues and returns. The results are important to functions such as pricing, marketing, accounting, and inventory and financial control in a container filling plant.     

A simulation study of container size in two-card kanban systems

Setting container sizes is one of the first decisions that users of kanban systems must address. Yet researchers have largely assumed container sizes to be given. This paper investigates the effect of container size on average inventory and customer service levels in a two-card kanban system processing multiple part types. Container size and the number of kanbans are varied in tandem so that total in-process inventory capacity remains constant. Simulation results show that smaller containers lead to smaller average total inventories. The surprise is that smaller containers do not always lead to poorer average customer service. Smaller container sizes can lead to better average customer service when the costs of greater total setup time are offset by the benefits of more frequent material handling, that is less frequent station material starvation, and improved finished goods part mix. This occurs primarily when container size is larger than average finished-goods order size and when setup times are relatively short.     

A comparative life cycle assessment of single‐use fibre drums versus reusable steel drums

This paper deals with a comparative analysis of two different packaging and transport scenarios, which exemplifies the implications of choosing between single‐use and reusable packaging. In particular, transport of a batch of chemicals by means of disposable fibre drums versus reusable steel drums is investigated from a life cycle perspective, and the associated environmental impact in terms of global warming potential, acidification potential, gross energy requirement and solid waste generation is assessed. Results prove beyond reasonable doubt that even in the case of durable packaging containers requiring the use of comparatively energy‐intensive materials for their production, the reuse scenario is characterized by lower environmental impact indicators across the board, and as such is the most advisable and environmentally sound option. Copyright © 2009 John Wiley & Sons, Ltd.     

Positioning empty containers among multiple ports with leasing and purchasing considerations

With the recent development of container transportation, the imbalance of empty containers among ports has become more serious. We consider the problem of positioning empty containers. The goal of this study is to propose a plan for transporting empty containers between container ports (terminals) to reduce the imbalance. There is currently a demand at each port and any backlog of containers is not permitted. The objective is to minimize the total relevant costs such as transportation cost, handling cost, and holding cost, etc. In this study, we develop a model with respect to the leasing and purchasing of containers. Mixed integer programming and genetic algorithms are used to solve the model. A hybrid GA is also proposed to reduce the computation time while still obtaining an acceptable result.     

Basic considerations on the calculation of the trippage number for returnable containers

The trippage number of returnable containers has a central position in economic, calculations and in comparing the environmental impacts of disposable and returnable container systems. Extremely varying trippage numbers are frequently reported for the same type of container, usually without any reference to the method of calculation. Only a few authors have published basic considerations on the calculation of the trippage number. Different methods of calculation have been recommended and different definitions of what should be understood by the ‘trippage number’ have been given. To investigate what is really achieved by these kinds of calculation, a model system, performing all the functions of a returnable container system in practice, for system analysis by computer simulation was established. By means of this model system it was found that in the lifetime of a container population one can differentiate between three kinds of populations, each one with an individual mean trippage number:

• (i) the average trippage number of all containers put into circulation
• (ii) the average trippage number of all lost containers
• (iii) the average trippage number of all existing containers, representing the total stock of circulating containers

Emanating from these basic considerations, it was found that the actual average trippage number of all containers put into circulation after ‘x’ fillings (U_x) can be calculated exactly by the quotientof the sum of all filled containers (ΣN) and the sum of all containers put into circulation (ΣE) since the first day of use of a container type according to the following expression It must be stated that correct results can only be achieved by taking into account all containers filled or put into circulation from the very first day of use. Despite this drawback, this kind of calculation has the advantage of being based on figures that are available and easily retraceable for almost all filling-plants. After the first circulation, the average trippage number (U_x) is equal to 1.0, rising with each circulation because of its tendency to approximate to a constant final value after an infinite number of fillings (U_x→∞), which can be calculated by the quotient of the sum of all filled containers (ΣN) and the sum of all lost containers (ΣA) since the first day of use of a container type, represented by the inverse value of the proportion of lost containers (a) or its complement, the share of refillable containers (r), according to This (theoretical) final value is approximated by each partial population (the population of all input new containers, of all lost and all existing containers) but with a different velocity, dependent on the parameters a=1?r (the loss rate) and r_z =1?b (the rate of containers returning to the filling-plant from the total stock of existing containers). The number of circulations needed to approach this final value rises with a decreasing share of lost containers (a) and with a decreasing share of containers returning to the filling plant (r_z) from the total container stock. The calculation by the inverse value of the share of lost containers (l/a ) is therefore not relevant to the calculation of the actual average trippage number of any partial population (number of new containers put into circulation, lost containers or stock of all existing containers). To receive correct results, also for this calculation, it is necessary to take into account all containers filled or lost from the very first day of use. This may be troublesome with a container type used by many filling-plants and with traditional old containers, where the necessary figures are no longer available. A further drawback of this kind of calculation is that the number of lost containers cannot be calculated exactly, because of the uncertainty of whether all containers, for which the plant holds the deposit, exist or not. Therefore the share of lost containers is mostly set too low, which results in the calculation of too high a trippage number.     

Estimating cycle time and return rate distributions for returnable transport items

A return rate distribution for returnable transport items (RTI) is estimated from radio frequency identification (RFID) data. The technique is dependent on estimating a probability density function for backward fill-to-fill cycle times for the returnable containers. The cycle time distribution yields an estimate of a time period where most containers will return to the manufacturer. To obtain return rate observations, the number of returns in a production lot is observed by tracking the fill and return of uniquely tagged containers over this time period, adjusting for containers with long cycle times. The process also gives an estimate of the percentage of RTI tagged in the population or fleet of containers. The effects of estimation errors due to a partial RFID-tagging of the fleet are examined, and satisfactory results can be obtained when not all containers are tagged. The use of the cycle time and return rate distributions for creating a forecast of container returns is illustrated, and implementation of cycle time and return rate as indicators of supply chain performance is discussed.     

A reusable flow-through polymerase chain reaction instrument for the continuous monitoring of infectious biological agents

Continuous monitoring of the environment for infectious diseases and related biowarfare agents requires the implementation of practical cost-effective methodologies that are highly sensitive and specific. One compatible method employed in clinical diagnostics is real-time polymerase chain reaction (PCR) analysis. The utility of this technique for environmental monitoring is limited, however, by the utilization of single-use consumables in commercial PCR instruments. This greatly increases mechanical complexity, because sophisticated robotic mechanisms must replenish the disposable elements. An alternative strategy develops an autonomous monitoring system consisting of reusable modules that readily interface with fluidic circuitry in a flow-through scheme. The reduced complexity should increase reliability while decreasing operating costs. In this report, we describe a reusable, flow-through PCR module that functions as one component in such a system. This module was rigorously evaluated with Bacillus anthracis genomic DNA and demonstrated high repeatability, sensitivity, and efficiency, with no evidence of sample-to-sample carryover.     

Data envelopment analysis of AGV fleet sizing at a port container terminal

A decision-making approach based on Data Envelopment Analysis (DEA) for determining the efficient container handling processes (considering the number of employed Automated Guided Vehicles (AGVs)) at a port container terminal (PCT) is presented in this paper. Containers are unloaded from the ship by quay cranes and transported to the storage area by AGVs. We defined performance measures of proposed container handling processes and analysed the effects when changing the number of AGVs. The values of performance measures were collected and/or calculated from simulation. Container handling process, with a fixed number of quay cranes, when a different number of AGVs is used to transport containers from berth to assigned locations within storage area, represents a decision-making unit (DMU). We applied the basic CCR (Charnes, Cooper and Rhodes) DEA model with two inputs: average ship operating delay costs and average operating costs of employed equipment at a PCT, and two outputs: average number of handled import containers per ship and weighted average utilisation rate of equipment at a PCT. DEA method proved to be useful when testing different DMUs and when determining efficient DMUs for planning purposes. This study shows that efficiency evaluation of AGV fleet sizing and operations is useful for planning purposes at PCTs.     

Life cycle inventory and analysis of re‐usable plastic containers and display‐ready corrugated containers used for packaging fresh fruits and vegetables

Today's demanding distribution challenges require engineers to choose from various types of materials, design and construction methods, to develop containers that can deliver goods with minimal damage. The challenge is even greater when packing and shipping goods which are perishable and sensitive to both physical and climatic changes in environment. In recent years the type of packaging material used to design and construct containers has undergone more scrutiny than ever, due to environmental challenges. This study focuses on two types of containers that have been designed and are being used to pack and ship fresh fruits and vegetables. The study compares the re‐usable plastic containers to single‐use display‐ready paper corrugated trays. Results show that, based on the scope of this study and comparing 10 different produce items, such as apples, carrots, grapes, oranges, onions, tomatoes, strawberries, etc., the re‐usable plastic containers require 39% less total energy, produce 95% less total solid waste and generate 29% less total greenhouse gas emissions. This study focused on the North American market. Major European nations have been using a large number of re‐usable plastic containers for these types of fresh produce for the past three decades. This study was initiated by the Franklin Associates, an independent consulting firm for allowing an in‐depth review of all data and results from a two year study titled: Life Cycle Inventory of Reusable Plastic Containers and Display‐Ready Corrugated Containers Used for Fresh Produce Applications. Copyright © 2006 John Wiley & Sons, Ltd.     

海陆联运下可折叠集装箱的空箱调运研究

目的针对空箱调运问题,找出影响可折叠集装箱使用的关键因素。方法利用因素分析法、整数规划法对标准集装箱和可折叠集装箱的总成本及影响因素进行分析,影响因素包括运输成本、折叠/展开成本、运输能力、存储成本及租箱成本等。结果租箱成本是影响可折叠集装箱使用的关键因素,当租箱成本降低10%以上时,使用可折叠集装箱比标准集装箱具有明显的经济性。结论可折叠集装箱的使用受多种因素的影响,在一定条件下使用可折叠集装箱优于标准集装箱。     

Environmental Balances of Thermal Superinsulations

This paper introduces environmental balances for three different thermal insulation concepts (evacuated multi-foils, evacuated glass fibers, and a conventional foam insulation) of a 300 L LN₂ storage tank. The calculations are based on material consumptions in the manufacturing phase and thermal losses of the tank during the use phase. Materials consumption is identified from the design of the tank taking into account stainless steel containers, thickness of container walls, mechanical supports, bellows, getter, and insulation materials. Thermal losses are calculated using finite element methods. It is demonstrated that evacuated multi-foil insulation is, from energetic and environmental considerations, by far superior to evacuated glass fibers and to conventional foam insulation. Its environmental “amortization time” (a return on investment when outbalancing environmental impacts by corresponding savings) is in the order of 80–160 weeks of operation. This also demonstrates that it is important to apply an environmental life cycle perspective, and not analyze only the energetic and materials aspects, when new technologies are assessed. Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Development of a human information processing model for cognitive task analysis and design

High costs and long cycle times of software development are factors hindering the analysis and design of the complete cognitive aspects related to task performances. Reusable software has been proposed as a solution to the problem of high software development and maintenance costs. One of the paradigms for reusable software, object-oriented modelling, has emerged as an important method for specifying, creating and reusing software modules. Using Unified Modelling Language, this paper develops an object-oriented cognitive task analysis and design (OOCTAD) model based on human information-processing theory. First, human task performance-related cognitive aspects are classified into modules and logically linked together; secondly, cognitive aspects within these modules were further decomposed into packages and classes based on object-oriented technology. Finally, one case study was presented to compare and contrast different cognitive analysis models to illustrate the advantages of the OOCTAD model developed in the current research over the other five cognitive task analysis models. These reusable classes in the OOCATD model were shown to be reused to reduce software development costs and cycle times for cognitive task analysis and design. The current research should be of use to both developers and users of cognitively based tasks, systems and tools and researchers and practitioners in the broader discipline of cognitive tasks design and analysis.     

船舶冷藏集装箱内部温度分布的模拟与优化

文章采用数值模拟的方法,采用CFD对20英尺冷藏集装箱进行建模和数值分析,采用旁通调节、两端回风和合理利用箱内温度梯度方式,通过仿真对冷藏集装箱内部温度分布进行优化分析,得到旁通调节在不增加机组负荷的情况下,能够增大送风速度,使箱内温度分布更合理均匀;下送风两端回风的方式可以明显改善箱内温度的分布,整体温度差能够控制在1．5℃以内,提高回风温度并能提高机组效率;通过分析模拟结果得到冷藏集装箱不同距离方向上的平均温度变化情况,根据冷藏温度和温度波动可以划分箱内区域,以达到合理利用冷藏集装箱内部温度和空间的目的。     

Collaborative solutions for inter terminal transport

Major ports contain multiple container terminals, sea terminals, train, truck and barge terminal, and empty container depots, operated by different companies. Port authorities try to streamline inter terminal container transport (ITT) within congested port areas by offering expensive common road and rail infrastructure. Alternatively, individual stakeholders can set up private or collaborative container transport systems. This paper develops a framework to analyse and determine feasibility conditions of a common ITT system in a port area, depending on total transport volumes. First, we develop a simulation model to evaluate the costs of transporting containers using different modes of transport including trucks, automated guided vehicles, and multi trailer systems. Next, the required number of vehicles per mode is determined for a given throughput and waiting time. The results of the simulation are used in a game-theoretic setting to determine the cost savings per stakeholder operating in a coalition. By comparing cost savings for all possible coalitions, it is possible to determine, for each stakeholder, the attractiveness of using a common system. We find the coalitions that result in the highest savings and compare them with the infrastructure cost required to realise them. We apply the method to determine the feasibility of a common ITT system for terminals in the Port of Rotterdam and show that it only pays off in case of high demand for container transports.     

Using artificial neural networks to predict container flows between the major ports of Asia

Container flow information is a critical issue for port operators and liners to support their strategic planning and decision-making. This study uses artificial neural networks (ANNs) to predict container flows by considering GDP, interest rates, the value of export and import trade, the numbers of export and import containers and the number of quay cranes. ANNs are developed for data mining purposes, and the developed model can simultaneously predict container flows between the major ports of Asia. The forecasting results indicate that the prediction errors are relatively small in most selected ports, and thus shipping companies can use the container flow prediction model to make decisions concerning operations. The results can be further applied to the trend analysis of container flows among the major ports of Asia, and a community analysis of the containers was conducted for the purpose of supply chain management.     

The economic burden of injury: Health care and productivity costs of injuries in the Netherlands

BackgroundDetailed information on health care costs and productivity costs for the whole spectrum of injuries is lacking. We measured the total costs of injuries by external-cause, injury groupings, age and sex.MethodInjury patients visiting an Emergency Department in the Netherlands were included. Health service use and work absenteeism were estimated with national database data and a prospective follow-up study. Health care costs (direct costs) and productivity costs (indirect costs) were determined using the incidence-based Dutch Cost of Injury Model.ResultsTotal costs of injuries were €3.5 billion annually (€210/capita and €4300/patient); €2.0 billion healthcare costs and €1.5 billion productivity costs. Home and leisure injury subcategory falls caused 41% of total costs. Traffic injury was prominent in the 15–54 age group, mainly due to bicycle injuries. Sports injuries, in special football/soccer injuries, resulted in high costs in the 15–24 age group. Although costs per patient were comparable between males and females, health care costs were higher in females, whereas males have more than twice as high productivity costs. Health care costs were highest for hip fractures (€20,000/patient). Extremity fractures had high costs due to high incidences and high productivity costs per patient.ConclusionOur detailed cost model identified known risk groups, such as elderly females with hip fractures resulting from falls, as well as less obvious important high risk groups, such as young children falling from furniture, young males who sustained football/soccer injuries and bicycle injuries among all ages. This information is essential to assess additional priority areas for prevention.     

预应力钢丝缠绕剖分-组合大型挤压筒的热应力分析

预应力钢丝缠绕剖分-组合挤压筒与传统挤压筒相比具有重量轻、疲劳性能好、制造难度与成本低等优势.传统的预应力钢丝缠绕筒体理论计算方法忽略了温度的影响,不适宜于热挤压筒的设计计算.该文采用线性热弹性理论、预应力钢丝缠绕理论以及弹性力学理论对挤压筒在预紧状态、预热状态和工作状态下的应力分布分别进行了分析,得出应力分布的解析公...     

Mixed integer programming for strategic decision support in the slaughter by-product chain

A mixed integer linear programming model to support strategic decision making is presented, in order to find the optimal processing structure for a slaughter byproduct business. In an integrated approach environmental objectives (such as odour emission, water pollution and energy consumption), market outlets, quality requirements (both for product and process), costs of processing, transportation, environmental measures and governmental restrictions are modelled to find the optimal investment strategy for future ways of processing slaughter by-products. Emphasis has not been put on development of new models or techniques. The value of this contribution is how to find new cost-effective logistical solutions within a framework of environmental restrictions, quality and technological opportunities.     

Life cycle inventory of HDPE bottle‐based liquid milk packaging systems

This study aims at providing a relatively straightforward methodology to serve as a decision‐making tool when more than one packaging solution could be available to a user. It involves a life cycle inventory (LCI) analysis and comparison of three currently available 3.79 l (1 gallon) packaging systems for liquid milk. Two of the primary container types studied use reusable plastic crates (RPCs) for stacking and shipping, while the third type is a heavier duty container that does not require secondary shipping containers. The three primary containers studied are identified as original, cube and stackable throughout this paper. The study shows that the use of RPCs for controlled environment distribution reduces the material requirements of the primary containers and therefore reduces the overall CO₂ emissions. It was also found that though the transportation‐related emissions varied between the packaging systems for the two end‐of‐life scenarios considered, it had the lowest overall effect on the CO₂ emissions and use of energy. The study concludes that transportation weight limits must be considered as a limiting factor in package design for liquid products, as trailers ‘weigh out’ before they ‘cube out.’ As related to the LCI impacts, this study found that the original and cube container‐based packaging systems have better overall per functional unit performance in comparison with the stackable design. It was also noted that scorecards based on the Wal‐Mart format do not accurately define the environmental impacts posed by packaging systems. Copyright © 2010 John Wiley & Sons, Ltd.