耕地地块细碎程度及其对山区农业生产成本的影响

在务农成本持续上涨和省工性技术普及的背景下,山区地块细碎化逐渐成为抑制农民增收的重要因素。厘清山区耕地细碎程度及其对农业生产的影响,对于降低农业生产成本具有指导价值。基于重庆市武隆区、巫山县和酉阳县的1015份农户调研数据,分别从地块权属和空间分布两个角度测算耕地细碎程度,并采用半对数经济计量模型评估耕地细碎差异对农业生产成本的影响。结果表明：研究区耕地细碎程度严重,辛普森指数和地块距离指数分别为0.71和0.19,户均耕地面积6.19亩、地块数8.89块,地块与家庭平均相距430 m,即呈现出“块数多、规模小和距离短”的特征;耕地细碎程度加剧提高了农业生产成本,当辛普森指数和地块距离指数每增加一个标准差时,单位产量总成本依次上升33.8%和16.6%;具体到各单项成本,耕地细碎程度加剧显著提高了劳动力、化肥和种子成本,而限制机械及其他要素的使用。分作物的实证显示,耕地细碎化效应存在明显的作物异质性。此外,优质耕地能缓解地块细碎带来的成本上升,同时扩大地块面积有助于降低生产成本。政策启示：降低农业经营成本是缓解山区耕地撂荒的重要举措,政府应建立低成本的农地流转网络,并鼓励农户或村庄之间的土地互换,提高地块规模和减少耕作距离,同时政府还应推广和普及适合山区农业的微耕机械。     

煤矿企业安全管理的代理成本影响因素及激励措施研究

为减少煤矿企业的代理成本,激励代理人的努力程度,从信息对称和信息不对称2个层面建立煤矿集团委托人和代理人之间的委托代理模型。并通过对2个模型的比较分析发现,代理成本的影响因素主要是由煤矿代理人的风险厌恶程度、事故发生的高度不确定性和努力的边际成本难以提高等3个因素决定的。从代理成本的3个影响因素角度出发,给出促进煤矿代理人努力开展安全管理的激励措施。     

面向新型航空装备系统的安全保障模式研究

四代机和大型运输机作为新型的航空装备,因其具有更为先进的技术性能,导致服役风险的增大。为促进国内四代机装备部队后战斗力的迅速形成,提出了一种基于和谐交互机制的安全保障模式。通过建立系统安全度模型,揭示了航空装备系统本质安全化的规律,即注重系统组元本质安全化的同时,强调系统组元内部及其与外界环境间的和谐交互作用。分析了系统安全保障模式中的人的本质安全化和环境的本质安全化,阐述了三类本质安全人的职责和相互关系;借用辐射理念,建立了系统安全辐射模型,提出安全辐射是扩大安全效益的有效手段;对航空装备系统本质安全化中的总效用和边际效用进行了数学描述,认为系统组元达到有机耦合是安全效用最大化的唯一途径,所述观点为新型航空装备的安全服役有一定指导意义。     

农地开发整理新增耕地价格评估

有序的农地流转市场需要有价格体系支持.以国家投资的一个重点农地整理项目为例,探讨了农地整理新增耕地价格的内涵、特点、价格评估的必要性、原则和估价方法的选择,并运用成本法评估了新增耕地的价格,旨在为目前我国全面开展的农地开发整理新增耕地入市价格评估提供实践依据.     

Does marginal price matter? A regression discontinuity approach to estimating water demand

Although complex pricing schedules are increasingly common among water and electricity providers, it is difficult to determine whether consumers respond to changes in the pricing schedule because price changes are often confounded with simultaneous demand shocks or non-price policies. To overcome this challenge, we exploit a natural experiment - the introduction of a third price block in an increasing block pricing schedule for water - in Santa Cruz, California. Using a regression discontinuity design, we find that consumers do respond to changes in marginal price. Doubling marginal price leads to a 12% decrease in water use (500 cubic feet per bill) among high-use households.     

基于多需求点的震灾应急物资调度模型研究

为了解决震后应急物资调度中,因不考虑各应急需求点灾情差异和需求差异带来的决策结果不够合理的问题,采用改进的专家打分法将收集到的灾情信息量化为灾情因子,在此基础上建立应急成本和应急延误时间的多目标模型。采用逐步法求解,为每一个应急需求点确定提供应急物资的供应点及供应量。将此方法运用到云南发生的某地震灾后救援中,计算得出与3个应急需求点对应的应急供应点及其供应量。     

Cardiovascular Load During Summer Work of Two Age Groups of Van-Rickshaw Pullers in West Bengal,India

Van-rickshaw is a popular mode of transport of people and merchandise in developing countries. The purpose of this study was to assess the effect of age on cardiovascular load of van-rickshaw pullers in the summer season (March-June) in real situations. In 142 participants, divided into 2 age groups (25-40 and 41-55 years), cardiovascular load was assessed on the basis of working and partial recovery heart rate (HR), predicted maximal HR, working maximal HR, average working HR, percentage of reserved HR, sum of recovery heart beats, percentage of recovery, relative and net cardiac cost, etc. Except for percentage of recovery, all parameters differed significantly between the groups and were significantly correlated with age. As this activity is very stressful, it places a heavy demand on the cardiovascular system. Therefore, age is an important factor for sustainability of the work, especially in a hot environment. Some ergonomic interventions are necessary to reduce cardiovascular load.     

Cost and Benefits of Implementing an Occupational Safety and Health Management System (OSH MS) in Enterprises in Poland

Abstract

This article presents a method of assessing the economic outcome of implementing an occupational safety and health management system (OSH MS). Developed at the Central Institute for Labour Protection – National Research Institute (Poland), this method focuses on identifying the economic expenses comprising bookkeeping and alternative cost incurred to implement and improve an OSH MS. The method was next used in a study in 20 enterprises. While varying greatly among those enterprises, the alternative cost of implementing and maintaining an OSH MS was much higher than the bookkeeping cost, which was also much lower than the cost of statutory prevention measures. The implementation of an OSH MS resulted in both tangible and intangible benefits, including reduced premiums for work accident insurance.     

The Polluter-Pays Principle and its Environmental Consequences for Industrial Waste Management

The paper maintains that, as a means toward achieving the ideal of a sustainable development, industrial waste should best be regarded in business-economic terms as having the same basic status as regular products. It is shown how an approach to proportioning industrial costs to waste that is described can be applied to the Polluter-Pays Principle in a way incorporating this principle into a company's internal estimation system. In two case studies presented, use of this approach is found to generate a waste-reducing incentive through showing waste to have a negative impact on estimates of profit.     

ALTERNATIVE DEMAND MODEL ESTIMATORS FOR BLOCK RATE PRICING1

ABSTRACT: Three alternative demand model estimators for water sold under block rate tariffs are examined. The models are conceptually discussed and empirically estimated using cross-section and time-series data from Tucson, Arizona. While all three techniques produce plausible elasticity estimates, the ordinary least squares and censored sample techniques are shown to produce statistically biased results.