Note on inventory models with Weibull distribution deterioration

This article explores the inventory model with a general demand rate function in which both the Weibull distributed deterioration and partial backlogging are considered. The inventory model discussed here is based on the important finding by Wu [Wu, K.S., 2001. An EOQ inventory model for items with Weibull distribution deterioration, ramp type demand rate and partial backlogging. Production Planning and Control, 12, 787–793]. There are four parts in our research. First, we derive the analytical framework of the inventory model for a general demand rate function1 1.?Based on detailed suggestions of Professor Wafik H. Iskander, Email: whiskander@mail.wvu.edu . Second, for the ramp type demand, we improve Wu's model to find the criterion to guarantee the existence and uniqueness of the optimal solution. Third, we develop a new model to compensate for the missing case in Wu's article. Fourth, we combine our results to show that our findings are applicable to the ramp type demand inventory model, so that the optimal solution is independent of the demand function. Finally, some numerical examples and graphs are provided to illustrate our discovery and demonstrate the application of our analytical framework.     

Health Risk Characterization of Chlorpyrifos Using Epidemiological Dose‐Response Data and Probabilistic Techniques: A Case Study with Rice Farmers in Vietnam

Various methods for risk characterization have been developed using probabilistic approaches. Data on Vietnamese farmers are available for the comparison of outcomes for risk characterization using different probabilistic methods. This article addresses the health risk characterization of chlorpyrifos using epidemiological dose‐response data and probabilistic techniques obtained from a case study with rice farmers in Vietnam. Urine samples were collected from farmers and analyzed for trichloropyridinol (TCP), which was converted into absorbed daily dose of chlorpyrifos. Adverse health response doses due to chlorpyrifos exposure were collected from epidemiological studies to develop dose‐adverse health response relationships. The health risk of chlorpyrifos was quantified using hazard quotient (HQ), Monte Carlo simulation (MCS), and overall risk probability (ORP) methods. With baseline (prior to pesticide spraying) and lifetime exposure levels (over a lifetime of pesticide spraying events), the HQ ranged from 0.06 to 7.1. The MCS method indicated less than 0.05% of the population would be affected while the ORP method indicated that less than 1.5% of the population would be adversely affected. With postapplication exposure levels, the HQ ranged from 1 to 32.5. The risk calculated by the MCS method was that 29% of the population would be affected, and the risk calculated by ORP method was 33%. The MCS and ORP methods have advantages in risk characterization due to use of the full distribution of data exposure as well as dose response, whereas HQ methods only used the exposure data distribution. These evaluations indicated that single‐event spraying is likely to have adverse effects on Vietnamese rice farmers.     

我国城乡老年人口生活质量比较研究

老年人口的核心问题是生活质量问题,对老年人口主观幸福感的关注有助于提高老年人口的生活质量.基于杭州市城乡老年人口主观幸福感的调查研究发现,城市老年人比农村老年人具有更强烈的主观幸福感.子女孝顺是影响城市和农村老年人主观幸福感的最主要因素;经济状况、对社区工作满意度、婚姻、性别等也是共同影响因素,但影响程度在城市和农村间存在差异.此外,在城市模型中,自我照料程度、子女个数等个人特征因素对老年人主观幸福感影响显著;在农村模型中,经济来源、对权益受侵害后的处理方式等经济和社会保障因素对老年人主观幸福感影响显著.总之,城乡老年人对提高生活质量的需求不同,城市老年人已侧重于对精神的需求,而农村老年人首先还需要物质的满足.     

打高尔夫的粉装丽人

女子打高尔夫的姿态是很美的,短裙高袜,束腰长发,挥竿伸臂的瞬间,展示了最活泼和最激情的霎那。但去过的几家高尔夫球场,见到打球的人多是男性,颇有些想不通。     

川中丘陵区小麦品种绵阳26号的产量构成因素分析

运用相关、通径分析的方法分析了四川省小麦主推品种绵阳 2 6号的产量及其构成因素之间的关系。结果表明 ,绵阳 2 6号小麦品种千粒重的变异不大 ,穗粒数是产量构成的最重要因素 ,合理的有效穗是高产的前提。     

商业企业自有品牌战略研究

深入分析品牌的作用和自有品牌的特性,并就自有品牌的创造、服务保障、法律保护等提出若干对策。     

Additive and Multiplicative Models and Multistage Carcinogenesis Theory

In light of the Armitage-Doll multistage carcinogenesis theory, this paper examines the assumption that an additive relative risk relationship is indicative of two carcinogens that affect the same stage in the cancer process. We present formulas to compute excess cancer risks for a variety of patterns for limited exposure durations to two carcinogens that affect the first and penultimate stages; and using an index of synergy proposed by Thomas (1982), we find a number of these patterns to produce additive, or nearly additive, relative risk relationships. The consistent feature of these patterns is that the two exposure periods are of short duration and occur close together.     

我国证券市场对中小投资者的权益保护

随着我国证券市场的不断发展,中小投资者逐渐成长为市场上一支重要的投资力量。但是,由于我国证券市场的相对不完善,对中小投资者的权益保护措施相对缺乏,中小投资者权益受损现象时有发生。保护中小投资者的合法权益,是规范证券市场的当务之急。     

我国公立高校收费行为分析

我国高等教育收费行为始于1980年高等教育经费由中央和地方分级核拨后,在需求诱致下各高校兴起的招收自费生、收取委培费的实践。这种制度创新正是所谓的免费制度无法实现潜在利益,从而使行为者产生了新的收费制度安排的需求。也正是由于学校单位从免费制度到收费制度的变迁收益,才提供了国家收费制度变迁的重要客观条件。此外,准市场化的内外环境也为高校收费制度改革提供了坚实的客观基础。