Intermodal Competition: Cargo Airships versus Long-Haul Trucking for Perishable Commodities

Intermodal competition changes with changes in technology, economics, and environmental concerns. Trucks and airships are generally considered not to be competitors, but this depends on the distance of haul. The tonne-kilometer cost of trucking rises much more quickly with distance than it does the cost of a cargo airship. At some distance, the two modes are direct substitutes. The costs of the Mexico-Canada refrigerated truck supply chain are compared with the costs of a 100t-lift, electrically-powered airship. The flight characteristics of the Hindenburg Zeppelin are used as a model for a modern cargo airship. The supply chain cost of trucking tomatoes is used to test the theorical proposition. The cost difference works out to about US10￠/kg (5￠/lb) advantage for trucking Mexican tomatoes to Canada. However, this cost disadvantage of the airship could be made up by their vibrationless ride, better air circulation and one-day service versus four days by truck. This alternative form of transportation could have a positive impact on worldwide north-south distribution of food. Airships can overcome trade barriers and distance to open new markets for perishable food exports. In addition, they would reduce the carbon emissions of transport. Canada imports 160,000 refrigerated truckloads of fruits and vegetables by from the southern US and Mexico. With an average driving distance of 3,000 km, these trucks emit 606,000 MT of CO2 annually. Airships powered by hydrogen fuel cells would have zero-carbon emissions. Markets are not yet incorporating the environmental advantage of airships in any freight comparison, but inevitably this will be important.

Reliability supply chain network design model for perishable products

The classical supply chain network(SCN)design problem is extended,where the candidate facilities are subject to failure and the products are prone to elapsed time deteriorion.First,the reliable SCN design problem is defined by introducing the probability that a facility may be prone to inactivity based on the analysis of perishable product characteristics.The perishable product SCN design problem is formulated as a 0-1 integer programming model.The objective is to minimize the weighted sum of the operating cost(the fixed plus transportation cost)and the expected failure cost.And then,the perishable product SCN design model is discussed and solved using the genetic algorithm(GA).The results show how to generate the tradeoff curve between the operating costs and the expected failure costs.And these tradeoff curves demonstrate empirically that substantial improvements in reliability are often possible with minimal increase in the operating costs.

Publish or Perish被引分析工具在外语教学研究中的应用

被引分析是最常见的科学计量学研究方法,主要用来证明作者或其成果在所属专业领域内的影响力。Publish or Perish是一种在线被引分析软件,依据Google Scholar数据库来查询作者或成果的被引次数,并提供相关的统计数据分析。文章主要介绍了该工具的功能及使用方法,并结合实例探讨了其在外语教学研究中的应用。

Model of Combined Transport of Perishable Foodstuffs and Safety Inspection Based on Data Mining

There is still no effective means to analyze in depth and utilize domestic mass data about agricultural product quality safety tests in china now. The neural network algorithm, the classification regression tree algorithm, the Bayesian network algorithm were selected according to the principle of selecting combination model and were used to build models respectively and then combined, innovatively establishing a combination model which has relatively high precision, strong robustness and better explanatory to predict the results of perishable food transportation meta-morphism monitoring. The relative optimal prediction model of the perishable food transportation metamorphism monitoring system could be got. The relative perfect prediction model can guide the actual sampling work about food quality and safety by prognosticating the occurrence of unqualified food to select the typical and effective samples for test, thus improving the efficiency and effectiveness of sampling work effectively, so as to avoid deteriorated perishable food’s approaching the market to ensure the quality and safety of perishable food transportation. A solid protective wall was built in the protection of general perishable food consumers’ health.

A Note on an Economic Lot-sizing Problem with Perishable Inventory and Economies of Scale Costs:Approximation Solutions and Worst Case Analysis

This paper presents an economic lot-sizing problem with perishable inventory and general economies of scale cost functions. For the case with backlogging allowed, a mathematical model is formulated, and several properties of the optimal solutions are explored. With the help of these optimality properties, a polynomial time approximation algorithm is developed by a new method. The new method adopts a shift technique to obtain a feasible solution of subproblem and takes the optimal solution of the subproblem as an approximation solution of our problem. The worst case performance for the approximation algorithm is proven to be （4√2 ＋ 5）/7. Finally, an instance illustrates that the bound is tight.

Intermodal Freight Network Design for Transport of Perishable Products

The amount of perishable products transported via the existing intermodal freight networks has significantly increased over the last years. Perishable products tend to decay due to a wide range of external factors. Supply chain operations mismanagement causes waste of substantial volumes of perishable products every year. The heretofore proposed mathematical models optimize certain supply chain processes and reduce decay of perishable products, but primarily deal with local production, inventory, distribution, and retailing of perishable products. However, significant quantities of perishable products are delivered from different continents, which shall increase the total transportation time and decay potential of perishable products as compared to local deliveries. This paper proposes a novel optimization model to design the intermodal freight network for both local and long-haul deliveries of perishable products. The objective of the model aims to minimize the total cost associated with transportation and decay of perishable products. A set of piecewise approximations are applied to linearize the non-linear decay function for each perishable product type. CPLEX is used to solve the problem. Comprehensive numerical experiments are conducted using the intermodal freight network for import of the seafood perishable products to the United States to draw important managerial insights. Results demonstrate that increasing product decay cost may significantly change the design of intermodal freight network for transport of perishable products, cause modal shifts and affect the total transportation time and associated costs.

Study of the Option Ordering Policy concerning Perishable Farm Produce Based on Revenue Sharing Contract

This paper considers the two-echelon supply chain system which consists of single agricultural producers and retailers,and analyzes the impact of sharing ratio on the option ordering quantity,and retailers and producers' expected profits.Studies have shown that in the case of decentralization,when the revenue sharing ratio is between 0 and 0.3,the option ordering quantity of farm produce is a decreasing function of the sharing ratio; when the revenue sharing ratio is between 0.3 and 1,the option ordering quantity of farm produce is an increasing function of sharing ratio; when the revenue sharing ratio is between 0.421 and 1,the agricultural producers and retailers' expected profits are an increasing function of sharing ratio.Finally,through the numerical calculation,the applicability of the conclusions is verified,to provide a reference for the supply chain management practices.

An Inventory Model for Perishable Items with Time Varying Stock Dependent Demand and Trade Credit under Inflation

In the classical inventory models, it is assumed that the retailer pays to the supplier as soon as he received the items and in such cases the supplier offers a cash discount or credit period (permis-sible delay) to the retailer. In this paper we presented an inventory model for perishable items with time varying stock dependent demand under inflation. It is assumed that the supplier offers a credit period to the retailer and the length of credit period is dependent on the order quantity. The purpose of our study is to minimize the present value of retailer’s total cost. Numerical examples are also given to demonstrate the presented mode.

考虑个体客户满意度的多车程生鲜品配送路径优化

随着生鲜电商的兴起,生鲜品的道路运输量越来越大,其配送任务越来越复杂,提升客户满意度是生鲜品配送的重要目标组成。文章以一个具有配送自主权的生鲜品供应商为研究对象,以整个计划周期内生鲜品配送的车辆运输成本最小及客户满意度最大为双目标,且客户满意度从顾客的个体视角考虑,构建双目标多车程带时间窗及考虑订单打包时间的车辆路径优化模型。基于ε-约束方法,设计了两阶段变邻域搜索(VNS)和模拟退火(SA)相结合的元启发式算法,基于车辆构造初始路线,并针对性地提出了3点改进措施,包括通过数学性质推导下界、减少求解过程中不必要的搜索空间以及规避求解过程中被支配解的后优化处理。最后,以Solomon标准算例为基础构造算例对所设计的算法进行了计算实验,其求解结果表明:其设计的算法具有有效性,并通过敏感性分析得出相关管理启示。

多维技术赋能易腐水果智能包装设计研究

目的寻求易腐水果包装智能设计的创新策略,在更好保护水果的同时延长易腐水果的保鲜期,提升易腐水果的附加值。方法调研当今市场上樱桃、草莓、猕猴桃、杨梅等易腐水果包装的弊病,明确设计的新方向,以安全为出发点,以新型技术为着力点,结合实例探索易腐水果包装智能设计的策略与方法。结果将生物基PH响应智能膜运用其中,可以实时监测水果状态。通过创新的包装结构,在盒中设置多孔外壁有效防止了水果因大量乙烯释放造成的腐烂现象的发生。可折叠性的包装结构更加保证了水果在流通环节中的新鲜度,数字化信息技术的渗融使得防伪技术更好甄别产品真假。结论易腐水果对包装有着相对特殊的要求,宜于从安全性、环保性、人文性角度进行考量,通过功能性包装材料运用、智慧型包装结构创意以及数字化技术赋能等方法与技术,实现包装智能化,为水果保鲜、护形、溯源、防伪等提供帮助,构建多重安全屏障。在强化特定水果品牌意识的同时提升大众的购物体验和健康消费幸福感指数。

考虑策略型消费者后悔行为的易逝品零售商最优库存策略

易逝品零售商降价销售时,策略型消费者往往会经历高价后悔和缺货后悔,这两种后悔行为均会降低他们的购买效用,从而影响零售商库存决策和利润。因此,本文分别研究了价格外生和内生两种情形下高价后悔和缺货后悔对策略型消费者行为以及零售商库存决策和利润的影响。研究表明,对于高利润产品,零售商应实施瞄准短视型消费者(target myopic consumers,TMC)的策略。相反,对于低利润产品,零售商应实施瞄准短视和策略型消费者(target both myopic and strategic consumers,TBC)的策略。此外,随着高价(缺货)后悔水平的增加,策略型消费者原来认为是低(高)利润的产品,现在可能认为是高(低)利润产品,因此零售商最优策略可能会相应地改变。其次,对于低利润产品,当高价(缺货)后悔显著时,后悔行为对零售商产生负(正)影响,且高价后悔和缺货后悔呈现相反的作用;对于高利润产品,后悔行为不对零售商造成影响。再次,对于低利润产品,高价后悔加剧了(缺货后悔缓解了)策略型消费者行为的负影响;对于高利润产品,后悔行为不影响策略型消费者行为的负影响。最后,当零售商拥有全价决策权时,零售商总是能够利用决策全价的优势来消除高价后悔的负影响或发挥缺货后悔的正影响。

寻找消失的遗产:基于多重证据的湮废园林复原研究方法

【目的】湮废园林涉及历史上因各种原因消失的园林,以及现存园林经重大改变前的早期风貌。中国园林早期的历史风貌是中国风景园林遗产的重要组成部分,其复原研究是风景园林历史理论研究的核心领域。【方法】探索多重证据在湮废园林复原研究中的运用:首先将复原证据分为现场实存、遗址考古、诗文文献、绘画图像、口述证言、相关实存和造园理论7种类型,按性质可分为实物证据、文献证据和言辞证据,按关联性可分为直接证据和间接证据;进而逐一辨析7类证据的特点,结合实例分析它们在复原研究中的应用。【结果】指出湮废园林复原过程中应注意证据的可用性与可靠性,关注证据之间的相互印证和证据的持续更新。【结论】尝试建立一套依据可靠、过程可操作的研究方法,为湮废园林复原研究提供方法论的参考。

代销平台参与下易腐农产品供应链决策研究

易腐农产品存在生命周期短、损耗率高等特性,所以对易腐农产品采用预售成为非常受欢迎的销售方式。在众多预售方法中,代销平台开展线上直播“预售+直销”的促销方式,使得易腐农产品能够更好地售卖。鉴于此,文章考虑由供应商和代销平台主导的二级供应链中,构建直播“预售+直销”模式下的供应链博弈模型,并对供应商和代销平台的利润和价格进行决策研究。研究发现:直销模式相比预售模式需要更高的佣金水平才能使销量提高。直销模式下折扣次数过多会导致供应商利润下降,但销量会增加。合理的佣金能够促进代销平台促销,且不会降低供应商最终利润。文章的研究结果可以为进行线上直播售卖并促销的代销平台提供支持,并为供应商和平台的最终利润提供理论依据。

热解温度对不同种类易腐垃圾生物质炭理化特性的影响

随着垃圾分类政策的推行,易腐垃圾减量化、无害化、资源化处理越来越重要,热解炭化是一条具有环境效益和经济效益的处理途径.本研究利用扫描电镜、X射线衍射、傅里叶红外光谱及比表面积分析等表征方法,系统地分析了热解温度对6种易腐垃圾生物质炭(甘蔗皮炭、豌豆荚炭、橘子皮炭、柚子皮炭、桂圆皮炭和厨余垃圾炭)理化特性的影响.结果表明:①热解温度是影响生物质炭理化特性的关键因子,随热解温度的升高,易腐垃圾炭产率降低,灰分含量、pH和EC值增大,表面-OH、C-H、C=O、C=C和C-O-C等官能团含量减少,CaC_(2)O_(4)和K_(2)C_(2)O_(4)等草酸盐逐步分解为CaCO_(3)和K_(2)CO_(3).当热解温度为650℃时,厨余垃圾炭的产率、灰分含量、pH分别为41.7%、57.4%、9.8.②生物质原料种类是影响生物质炭理化特性的另一关键因子,不同种类的生物质炭表面元素含量、比表面积和形貌结构等参数均不相同,厨余垃圾炭的产率、灰分含量、表面钠元素和钙元素含量明显高于其他易腐垃圾炭.③易腐垃圾热解炭化主要包括脱水、脱羧、聚合、芳构化等过程,采用热解炭化技术处理易腐垃圾的毛利润约为630元/t,既具有环境效益又具有经济效益.上述研究结果为拓宽易腐垃圾炭资源化利用途径提供了基础数据,可有效助力无废城市建设.

易腐浆果类可食涂膜保鲜技术研究进展

浆果类水果皮薄多汁、质地柔软,易受到机械损伤与病原菌侵染,是最难保存的果蔬种类。可食涂膜保鲜具有安全可食、隔绝保护、抑菌杀菌及增加营养价值等特点。概述了易腐浆果常用的保鲜技术,重点梳理了可食性涂膜最新研究结果,以期为易腐浆果保鲜提供参考。

双渠道供应链下易腐品的库存和定价决策

以现实易腐产品供应链为背景,研究单一零售商和单一供应商组成的双渠道供应链模型,即供应商可通过直接在线渠道和间接零售渠道销售易腐产品,除了产品数量下降外,产品质量也会随着时间的推移而下降,同时,产品质量的下降会影响零售渠道的需求率。分别建立集中式和分散式两类模型,并提出相应算法求解最佳价格、订购频率和订购周期等。结果显示,分散式的供应链不仅会侵蚀两家公司的利润,并且产品的浪费率也较高。通过采用收入分享和二部定价法的方式能够协调供应链,减少供应链的总浪费率。同时,随着产品劣化率的提高,两家公司会更倾向于进行供应链协调,协调合同对零售商利润的提升更为显著。在模型扩展部分考虑直接渠道的交货时间,结果表明,分散式模型的供应商会投入更多资金以缩短交货时间。

生产能力约束下易逝品动态批量决策研究

针对易逝品在生产能力有限的情况下的决策问题,首先通过构建包含生产成本和库存持有成本在内的成本最小化模型,分析了生产成本和库存持有成本为一般化的单调递增凹函数的最优动态批量决策和相互影响。然后通过求解模型得出了最优解的结构特性,并设计出前向动态规划算法以及分析了无投机性成本结构的特殊情形。研究发现:在生产计划中,不同周期生产的产品库存应按照先进先出的原则满足各周期需求;若任意周期的需求都不大于生产能力,则著名的零库存性质在时间依赖的库存损失率及库存持有成本和生产能力双重约束下仍然成立。

努力水平影响损耗的低值易逝品TPL协调合同

对于一类低值易逝品,损耗与物流服务价格是影响这类产品订购与销售价格决策的重要影响因素.主要研究了第3方物流服务提供商的努力水平会影响到客户企业产品的数量和质量损耗情形下的物流外包渠道优化与协调问题.通过建立动态博弈模型,分析了传统交易价格合同下双方的决策行为,结果表明双方的决策冲突会导致产品订购量和销售价格的扭曲,但不存在努力水平的扭曲,进而会导致次优渠道绩效.为了解决这一问题,设计了收入共享与努力成本共担合同,并论证了在一定条件下这一合同可以实现渠道协调、双方共赢.最后,相应的算例表明努力水平影响产品质量和数量损耗的程度会对双方、集中式系统的决策行为和绩效产生重要的影响.

基于RFID技术的易逝品供应链库存协调

针对易逝品供应链节点企业库存数据不准确的问题,考虑采用射频识别技术和不采用射频识别技术两种情形,建立了集中决策下供应链系统以及分散决策下零售商、供应商的订货(生产决策)模型;分析了分散决策下节点企业的最优策略。通过分析和比较采用射频识别技术前后的最优收益,确定了射频识别技术在供应链中的应用条件和应用策略;进一步建立了推进射频识别技术应用的供应链协调模型,给出了上下游企业达到协调的条件。最后通过算例分析,验证了射频识别技术应用策略与供应链协调策略的有效性。

易腐物品物流配送中心选址的遗传算法

在分析物流配送中心的作用及其现存选址方法的基础上，建立了一种求解易腐物品配送中心选址问题的算法，此算法为和ＡＬＡ法相结合而成的遗传算法。实验结果表明这一启发式算法明显优于ＡＬＡ法，不失为求解易腐物品配送中心选址问题的一种好方法。