Optimal decision of retailer for replenishment cycle under a deteriorating product supply chain

In order to minimize the total cost of the retailer, an optimal replenishment cycle is studied by considering the deteriorating product, two-level trade credits, the limited storage capacity of their own warehouse and credit-linked order quantity simultaneously. A two-echelon supply chain model, which consists of a supplier and a retailer, is established. Then, the retailer＇s optimal replenishment cycle under all the cases are derived by using the optimization theory and method. On the basis of these, the effects of system parameters on the optimal replenishment cycle are examined by using the numerical studies. The results show that, when the retailer＇s trade credit period is longer （shorter） than the customer＇s trade credit period, the optimal replenishment cycle should he increased （decreased） as the retailer＇s trade credit period increases; if the minimum order quantity is high （low）, the optimal replenishment cycle should be increased （not changed） as the minimum order quantity increases.

Mechanical Modeling and Analysis of Stability Deterioration of Production Well During Marine Hydrate Depressurization Production

Different from oil and gas production,hydrate reservoirs are shallow and unconsolidated,whose mechanical properties deteriorate with hydrate decomposition.Therefore,the formations will undergo significant subsidence during depressurization,which will destroy the original force state of the production well.However,existing research on the stability of oil and gas production wells assumes the formation to be stable,and lacks consideration of the force exerted on the hydrate production well by formation subsidence caused by hydrate decomposition during production.To fill this gap,this paper proposes an analytical method for the dynamic evolution of the stability of hydrate production well considering the effects of hydrate decomposition.Based on the mechanical model of the production well,the basis for stability analysis has been proposed.A multi-field coupling model of the force state of the production well considering the effect of hydrate decomposition and formation subsidence is established,and a solver is developed.The analytical approach is verified by its good agreement with the results from the numerical method.A case study found that the decomposition of hydrate will increase the pulling-down force and reduce the supporting force,which is the main reason for the stability deterioration.The higher the initial hydrate saturation,the larger the reservoir thickness,and the lower the production pressure,the worse the stability or even instability.This work can provide a theoretical reference for the stability maintaining of the production well.

Fuzzy Inventory Model with Variable Production and Selling Price Dependent Demand under Inflation for Deteriorating Items

The main purpose of this paper is to develop an inventory model under fuzzy approach by considering the effect of inflation and time value of money, to determine the optimal time period for inventory cycle and minimum total average costs. The model is integrated production inventory model developed where;the Demand has a direct linear impact on production rate. The model can be divided into four stages. In the first two stages with original production rate and subsequent change in production rate, inventory level rises. Third stage is time after the accumulation of inventory and before the deterioration starts, where demand which selling price dependent is depreciating the inventory level, while in the fourth stage deterioration occurs, which is considered to follow two parameter Weibull distribution. The back-order is not considered. Hexagonal fuzzy numbers are used to derive optimum solution and defuzzification by graded mean integration representation method. A numerical example is given to demonstrate the applicability of the purposed model and sensitivity analysis is carried out to reveal the impact of change in parameter values.

Optimal production lot size with process deterioration under an extended inspection policy

A mathematical model to determine the optimal production lot size for a deteriorating production system under an extended product inspection policy is developed. The last-K product inspection policy is considered so that the nonconforming items can be reduced, under which the last K products in a production lot are inspected and the nonconforming items from those inspected are reworked. Consider that the products produced towards the end of a production lot are more likely to be nonconforming, is proposed an extended product inspection policy for a deteriorating production system. That is, in a production lot, product inspections are performed among the middle K1 items and after inspections, all of the last K2 products are directly reworked without inspections. Our objective here is the joint optimization of the production lot size and the corresponding extended inspection policy such that the expected total cost per unit time is minimized. Since there is no closed form expression for our optimal policy, the existence for the optimal production inspection policy and an upper bound for the optimal lot size are obtained. Furthermore, an efficient solution procedure is provided to search for the optimal policy. Finally, numerical examples are given to illustrate the proposed model and indicate that the expected total cost per unit time of our product inspection model is less than that of the last-K inspection policy.

Pricing and inventory decisions for non-instantaneous deteriorating items with price and promotional effort stochastic demand

This study investigates an inventory model for a non-instantaneous deteriorating item with partial backlogging wherein the demand is stochastic in nature and depends on price and promotional effort whereas the deterioration rate is time proportional.Under these settings,a mathematical model is developed with the objective to maximise the expected profit per unit time by determining the optimal price and the length of replenishment cycle.Some useful theoretical results are established to deduce the optimal replenishment schedule.An effective algorithmic procedure is developed to find the optimal solutions to the proposed model.The applicability of the proposed model is illustrated by numerical example.Sensitivity analysis of the optimal solution with respect to key parameters has been carried out and the implications are discussed.The study indicates that though promotional effort stimulates the market demand,it is beneficial in an economic sense when it applies in a conservative manner.

Progress on odor deterioration of aquatic products:Characteristic volatile compounds,analysis methods,and formation mechanisms

Odor is important in production,consumption,and science research of aquatic products.With the change in freshness in the storage and processing,the unique odor of aquatic products fade,fishy,foul odor,and other characteristic odor increased gradually,and the quality deteriorated.It greatly affected the development and utilization of aquatic products.At present,there are few summaries and explanations related to odor deterioration in aquatic products,which influence the progress of research on odor of aquatic products and understanding of odor deterioration.This study reviewed the characteristic odor compounds,various volatile compounds analysis techniques,and odor deterioration mechanisms of aquatic products.Through qualitative and quantitative analysis of volatile compounds,odor analysis technology creates the aroma fingerprint and flavor profile,reveals the source of sample aroma,and analyzes odor changes.It mainly focused on the effects of lipids,proteins,and microorganisms on the odor quality,to provide theoretical basis for the regulation of odor quality of aquatic products.

水产品劣变机制及其保鲜技术研究进展

水产品因其低脂肪、高蛋白、肉质鲜美等特点深受消费者喜爱,但水产品水分含量高、营养丰富等特性导致其在贮藏、运输过程中易受自身或环境因素影响而发生腐败变质。本文综述近年来国内外水产品保鲜技术研究现状,重点阐述冰晶形成、脂质氧化、蛋白质氧化、微生物侵染等造成水产品劣变机制,展望水产品保鲜技术发展趋势,旨在为水产品加工保鲜技术研究提供参考。

预制水产品在贮藏过程中的品质劣变机理及调控研究进展

预制水产品因营养丰富、味道鲜美而逐渐成为市场消费的“新宠”,但水产品原料富含水分和蛋白质,贮运过程中易发生腐败、变味、变色,因此,保鲜技术是保障预制水产品高质量的关键。本文综述导致预制水产品在贮藏过程中品质劣变的原因及保鲜技术的研究现状,以期为深入研究预制水产品在储藏过程中品质劣变机理及合理控制利用提供参考,进一步推动预制水产品的发展。

水产品劣变机制及其保鲜剂研发研究进展

水产品因其味道鲜美、富含蛋白质、必需氨基酸、多不饱和脂肪酸及微量元素而备受消费者青睐。低温贮藏是水产品最常见的贮藏手段,然而水产品肌肉组织薄、水分含量高、蛋白含量高等特点使其易在低温贮藏过程中出现汁液流失、蛋白质变性、脂质氧化、微生物生长繁殖等品质劣变现象。为充分探究水产品劣变机制,低场核磁共振技术(low field nuclear magnetic resonance,LF-NMR)、核磁共振成像技术(magnetic resonance imaging,MRI)、基于16S的二代高通量测序技术、蛋白质组学与脂质组学等新技术逐步应用于水产品低温贮藏过程中水分迁移、微生物作用、蛋白质与脂质生物大分子氧化降解反应的研究中。基于水产品劣变现象及其机制的研究,水产品保鲜技术得以开发应用。水产品保鲜剂按性质可分为盐类保鲜剂、酚类保鲜剂、糖类保鲜剂、蛋白类保鲜剂等,因具有成本低廉、操作简便的优势而被广泛开发应用。本文对水产品贮藏过程中常见的劣变现象及其机制的研究进展进行了综述,总结了水产品保鲜剂的研发现状,并对未来水产品劣变机制研究与水产品保鲜剂的发展前景进行了展望,以期为水产品保鲜剂的开发利用提供参考。

不同乳酸菌添加剂对青贮黑麦草和青贮玉米发酵产物和有氧稳定性的影响

在青贮黑麦草(Lolium perenne)和青贮玉米(Zea mays)中添加鼠李糖乳杆菌和布氏乳杆菌,研究其对发酵产物与有氧稳定性的影响。青贮饲料贮藏时间为14,56和120d。无添加青贮黑麦草发酵产物中乙醇含量较多,在14d开封时,乙醇和2,3-丁二醇含量为乳酸和挥发性脂肪酸总和的7倍。添加鼠李糖乳杆菌与布氏乳杆菌可以抑制乙醇型发酵,使乳酸型与乙酸型发酵占主导。无添加青贮黑麦草与添加鼠李糖乳杆菌的黑麦草发生了有氧腐败,但是添加布氏乳杆菌的黑麦草保持了有氧稳定。在青贮玉米中,添加鼠李糖乳杆菌未影响发酵品质,但添加布氏乳杆菌增加了发酵产物中乙酸含量,降低了乳酸含量。添加布氏乳杆菌的青贮玉米从56d开封开始保持了有氧稳定,其它组在120d开封时保持了有氧稳定,所有组乙酸含量都增加。

几种海产品储藏期间组胺含量及其品质的变化

本文测定了7种海产品在冷藏、冻藏、室温等条件下储藏或放置期间组胺含量的变化,观察了各海产品在上述条件下其品质的劣变情况。结果显示:冻藏是海产品较为理想储藏方法,其组胺含量增加缓慢,品质的劣变不明显;冷藏下海产品的组胺含量增加及品质劣变较快;室温下和室温盐水中放置,组胺含量的增加很快,品质的劣变明显,24h内就直接影响其可食性。

干旱、半干旱草原退化、沙化区的重要选择——设施草业生产

针对干旱、半干旱草原退化、沙化区传统的靠天然草地的放牧型草原畜牧业走到了一个十分困难境地的现实 ,指出了在严重缺水地区发展露天人工草地会带来新的沙漠化和土地退化。提出了具有高技术、高投入、高产出特征的牧草生产新观念——设施草业。设施草业生产方式是牧草在日光温室内生长 ,如同在工厂内进行草业生产。其生产系统包括加热系统、降温系统、通风系统、遮阳系统、微灌系统和中心控制系统。设施草业生产技术包含了现代农业的主要技术特征 ,主要包括种子工程、栽培技术、病虫害防治、加工保存和利用技术等。中国农科院草原研究所在内蒙古苏尼特左旗草场极度退化区开展了设施草业生产的初步试验 ,引种的高丹草在 2 0 0 1年 4月 2 5日～ 9月 2 4日期间收获 4茬 ,获得了 180 t/ hm2 的收获量。

易变质性产品生产商和销售商库存协调模型

本文基于如下假定:1)生产商的生产率为有限值且采取两阶段生产供货模式;2)生产的产品具有易变质性.在此假定下,建立了单生产商单销售商生产销售协调模型.讨论了如何利用价格折扣策略来激励销售商的订货行为.在保证销售商利润不减的前提下,给出了求解使得生产商利润达到最大化的最优价格折扣算法,同时给出了生产商的最优供给批量和销售商的最优订货批量.最后,用数值实例来验证模型的求解过程.

微冻技术在水产品保鲜中的研究进展

本文概括介绍了微冻保鲜技术的原理与发展现状,从反映鲜度的K值、TVB-N值、p H、微生物指标、汁液损失与质构等指标着手,结合水产品肌肉组织结构的微观观察,分析微冻贮藏期间冰晶的形成机理,阐述微冻保鲜对水产品贮藏期间品质影响的应用研究进展与存在的问题。

肉制品腐败变质原因分析

对真空软包装肉制品腐败变质原因分析表明:生物性因素是主要原因之一,污染微生物是乳酸球菌和芽胞杆菌;变质产品中的微生物数量及因此造成的酸化,不足以单方面造成产品变质,与产品含水量有关,是生物因素与非生物因素联合作用导致产品液化胀袋而变质;乳酸球菌由污染的冻结肉携带,而污染的芽胞杆菌是生产器具消毒不彻底造成的。

基于需求预测的短生命周期产品订货策略研究

本文针对短生命周期产品的特点,考虑与需求因子相关的库存短缺拖后和无形变质,根据缺货时间点、订货时间点与产品到达成熟期的时间点之间的关系,建立基于短生命周期产品需求预测的3种订货策略模型:乐观订货策略,悲观订货策略和中庸订货策略模型,对模型进行了分析求解,对最优解的存在性进行了证明.然后根据实际销售数据进行需求预测和算例分析,分析各因子对于总库存成本、订货量、短缺拖后量、销售损失量以及最优订货策略的影响.最后通过订货策略分析,分析各因子对于最优订货策略的影响,并将它们划分为3种订货策略影响因子,分析结果可以指导企业在不同因子水平情况下如何调整订货策略,以降低总库存成本.

易变质新产品定价与补货联合决策模型

考虑新产品情境下,产品扩散,重复购买和产品变质特征对企业定价与补货决策的影响.将重复购买率引入包含价格效应的Bass模型构建了需求演化函数,从而建立了易变质新产品定价与动态批量补货联合决策模型,设计了求解算法,并给出了算例分析.结果显示,定价与补货联合决策是必要的.最优价格与产品扩散速度及重复购买率呈先减小后增大的U型关系.最优价格随着消费者主动购买意愿的增加而增大,随着产品易变质程度的增加而减小.

水泥砂浆TSA侵蚀破坏过程的性能演变

研究了不同水灰比的掺石灰石粉水泥砂浆在低温硫酸盐溶液中长期浸泡后的外观、强度与矿物成分变化过程,分析了水泥砂浆受TSA侵蚀后的宏、微观性能演变规律.结果表明:TSA侵蚀是一种由外及里、逐渐发展的腐蚀破坏过程,降低水灰比可有效减缓TSA侵蚀破坏速率.从微观角度分析,将TSA侵蚀过程分为四个阶段:离子迁移期,钙矾石生成期,石膏生成期和碳硫硅酸钙生成期.根据力学性能变化与外观破损过程,TSA侵蚀又可分为三个阶段:潜伏期、膨胀开裂期和软化解体期.

随机生产中拖后需求的变质产品最优生产策略

针对部分短缺量拖后的变质产品,建立随机生产状态下的生产-库存模型.所谓随机生产状态,是指生产过程会随机地从一种可控状态向另一种不可控状态转移,当生产处于不可控状态时,会生产出一定比例的次品.其中,生产状态的转移服从均匀分布.通过生产-库存模型得到了随机生产状态下总成本函数,分析得到,该总成本函数是一个关于生产次数的凹函数,并由此提出了最优生产次数算法.最后给出了算例.算例结果表明,最优生产次数算法能够有效地将一个4n+1维的最优问题转化为一个一维问题,为变质商品的生产-库存决策提供了简便有效的方法.

变质性物品的生产库存系统的最优管理

将生产速度和销售速度相匹配 ,并使库存量保持在一定的水平 ,利用最优控制理论研究了具有变质性的物品的生产 库存系统的最优管理问题 ,导出了最优管理策略及最优生产率的解析解 ,指出要求的生产速度须在销售速度的基础上依库存量的大小进行校正·最后将最优生产率与不考虑变质时系统的最优生产率进行了比较·结果表明 ,变质现象并不能使最优生产率绝对地大于或小于不考虑变质时系统的最优生产率 。