不确定环境下柔性生产配置风险与损失

消费者需求的多样性和不确定性以及激烈的市场竞争促使企业在多样化产品生产中采取更加灵活的柔性生产策略。本文分析了流程柔性的实现方式,构建了需求不确定环境下多阶段、多产品柔性生产配置模型。将柔性生产配置风险分为需求不确定导致的浮动风险以及生产多阶段和设备能力限制导致的阶段分解风险两类,给出了不同类别风险的度量方法。通过配置损失指标来比较不同的柔性配置方式,采用数值仿真方法证明了链式配置是一种有效的配置方式,其具有较小的配置风险和配置损失,容易实现且生产成本相对较低。

土地资源配置的效率损失与优化途径

研究目的:通过构建土地资源配置效率损失模型探讨土地资源配置过程中的效率损失测算与优化途径选择,为加强与改善土地宏观调控提供参考。研究方法:数理分析与计量方法。研究结果:(1)2004年以后土地资源部门收益差距比规模配置欠优导致的配置效率损失更大;(2)部门收益差距效率损失增大导致了土地资源部门配置效率损失增大;(3)中、西部建设用地边际收益小于东部导致了建设用地空间效率损失。研究结论:(1)通过测算土地资源配置效率损失能够找到最佳的优化配置途径;(2)当前提升农用地边际收益和重点提升中、西部建设用地边际收益是优化土地资源配置的最佳途径。

我国葡萄酒制造业市场势力和配置效率损失测度——基于新经验产业组织模型

市场势力的定量测度以及福利损失的有效估算是政府经济管制和反垄断的基础。本文依据2000~2014年的行业整体数据,采用NEIO模型,对我国的葡萄酒制造业的市场势力和配置效率及其损失进行了测评。结果显示,我国葡萄酒制造业有一定的市场势力,但这种市场势力并不强,其配置效率损失也介于以往文献测算过的烟草加工业和啤酒制造业之间。

中国烟草加工业的市场力量与配置效率损失估测

中国烟草行业的专卖制度在限制产量的基础上确保了中央和地方财政收入的稳步增长,其代价是消费者利益受损和配置效率的降低。本文根据1985～1999年的行业整体数据,运用 NEIO 模型和 AEL 模型,定量估测了中国烟草加工业的市场力量和资源配置效率损失。结果显示中国烟草加工业富于市场力量,由此而造成的配置效率损失高达20%以上并出现不断加剧的趋势。

Productivity prediction model and optimal configuration of herringbone multilateral well

In order to accurately predict the productivity of herringbone multilateral well,a new productivity prediction model was founded.And based on this model,orthogonal test and multiple factor variance analysis were applied to study optimization design of herringbone multilateral well.According to the characteristics of herringbone multilateral well,by using pressure superposition and mirror image reflection theory,the coupled model of herringbone multilateral well was developed on the basis of a three-dimensional pseudo-pressure distribution model for horizontal wells.The model was formulated in consideration of friction loss,acceleration loss of the wellbore and mixed loss at the confluence of main wellbore and branched one.After mathematical simulation on productivity of the herringbone multilateral well with the coupled model,the effects of well configuration on productivity were analyzed.The results show that lateral number is the most important factor,length of main wellbore and length of branched wellbore are the secondary ones,angle between main and branched one has the least influence.

Optimal Allocation of EG in Distribution System Using Genetic Algorithm Technique

The interconnection of Embedded Generation （EG） in a distribution network would change the radiality of the convention power flows in the system. Instead of helping to reduce the system losses, it also improves the quality of the overall system network. However, improper allocation and sizing of its interconnection to the system could oppositely change those advantages. The total system may experience higher losses and instability. In this paper, a new technique to determine the optimal allocation of EG in distribution system by using Genetic Algorithm （GA） technique is proposed. The effectiveness of the technique is demonstrated using IEEE-69 bus distribution test system and simulated in MATLAB.

我国经济增长中的效率损失问题探析

改革开放以来,我国经济增长取得了举世瞩目的成就,但在经济增长中仍然存在一些缺憾,即社会经济资源并未达到最充分的利用状态,突出地表现为经济周期波动下的资源配置效率损失和不均衡发展下的经济结构效率损失。为了进一步提升我国经济增长的效率,应以科学发展观为指导,确定适宜的经济增长目标区间,熨平经济周期波动,提升宏观资源配置效率;改善投资和消费关系,降低储蓄率,提高投资效率,优化产业结构与就业结构,提升经济结构效率等。

Evaluation of convective heat transfer in a tube based on local exergy destruction rate

In this study, exergy efficiency is defined to evaluate convective heat transfer in a tube based on the local exergy destruction rate from the equilibrium equation of available potential. By calculating this destruction rate, the local irreversibility of convective heat transfer can be evaluated quantitatively. The exergy efficiency and distribution of local exergy destruction rate for a smooth tube, an enhanced tube into which short-width twisted tape has been inserted, and an optimized tube with exergy destruction minimization are analyzed by solving the governing equations through a finite volume method(FVM). For the smooth tube, the exergy efficiency increases with increasing Reynolds number(Re) and decreases as the heat flux increases, whereas the Nusselt number(Nu) remains constant. For the enhanced tube, the exergy efficiency increases with increasing Reynolds number and increases as the short-width rate(w) increases. An analysis of the distribution of the local exergy destruction rate for a smooth tube shows that exergy destruction in the annular region between the core flow and tube wall is the highest. Furthermore, the exergy destruction for the enhanced and optimized tubes is reduced compared with that of the smooth tube. When the Reynolds number varies from 500 to 1750, the exergy efficiencies for the smooth, enhanced, and optimized tubes are in the ranges 0.367–0.485, 0.705–0.857, and 0.885–0.906, respectively. The results show that exergy efficiency is an effective evaluation criterion for convective heat transfer and the distribution of the local exergy destruction rate reveals the distribution of local irreversible loss. Disturbance in the core flow can reduce exergy destruction, and improve the exergy efficiency as well as heat transfer rate. Besides, optimization with exergy destruction minimization can provide effective guidance to improve the technology of heat transfer enhancement.