边坡工程加固需求度评价及其应用

稳定程度不足的边坡通常都需要进行加固。但在加固系统设计时工程师们必须搞清边坡的哪些部位应进行重点加固 ,哪些部位只需要一般加固 ,甚至不需要加固 ,以便合理地布置加固措施。在工程地质力学综合集成方法论 (EGMS)的基础上 ,作者提出了边坡工程加固需求度 (DRD)的概念及其应用方法。     

快速测定工业废水化学需氧量

通过实验得出消解最佳实验条件为:催化剂NiSO4-CuSO4配比为80∶20,消解温度185℃、消解时间15min.本法测定的CODCr值与标准回流法所得结果一致,但本法比标准回流法省时.     

基于损耗率和需求不确定情况下的订购批量

库存管理模型在现实生活中有着广泛的运用。然而,在实际生活中,由于种种不确定性原因的影响,使得经典的确定型的EOQ模型的运用越来越不符合现实的需要;本文将需求和损耗率看成模糊数的同时,将物品的销售价格分成两部分来进行处理,即:没有损耗的产品以一种较高价格出售,对于有部分损耗的产品则按较低的价格出售;采用概率论置信区间估计的方法构建模糊变量的波动区间,构建使得总的利润达到最大的模糊库存模型,并利用三角模糊数、符号距离的方法以及最优化理论进行处理,得出满足条件的最优订购批量。最后,给出了模型分析和算例分析;通过分析,我们发现模糊库存模型的优点在于它自生所具有的不确定性;从数据上看,模糊库存模型比经典的库存模型更能反映出实际情况。     

Conditions that cause risk pooling to increase inventory

We say product A is a partial substitute for product B if a fraction of the customers who prefer B are willing to accept A when B is out of stock. When demand is uncertain, it is intuitive and true that a larger “willing to substitute” fraction implies larger expected profits. A higher “willing to substitute” fraction allows one to pool the risk of individual products. It may also be intuitive that a larger “willing to substitute” fraction might result in lower optimal total inventory. For the full substitution structure, several researchers have shown that for certain distributions such as the exponential, this latter intuition is not true. We show that this full substitution anomaly can occur with any right skewed demand distribution. We assume i.i.d. demand distributions unless we indicate otherwise. We also show that the anomaly can occur for a number of realistic situations of partial substitution with commonly used demand distributions such as Normal, exponential, Poisson, and uniform. We also demonstrate the anomaly for more than one period, with backlogging, lost sales, more than two products, and with setup costs.     

A note on Liu–Iwamura’s dependent-chance programming

Sometimes a complex stochastic decision system undertakes multiple tasks called events, and the decision-maker wishes to maximize the chance functions which are defined as the probabilities of satisfying these events. Originally introduced by Liu and Iwamura [B. Liu, K. Iwamura, Modelling stochastic decision systems using dependent-chance programming, European Journal of Operational Research 101 (1997) 193–203], dependent-chance programming is aimed at maximizing some chance functions of events in an uncertain environment. In this work, we show that the original dependent chance-programming framework needs to be extended in order to capture an exact reliability measure for a given plan.     

基于全光谱分析的水质化学耗氧量在线监测技术

针对水体中化学需氧量在线监测的迫切需求,设计了一种基于全光谱分析的水质化学耗氧量监测系统.该系统通过测量已知化学耗氧量的水质吸收光谱,利用最小二乘法建立吸光度与化学耗氧量的传输方程;针对待测水样,通过已建立的传输方程来反演水体化学耗氧量的浓度.通过模拟复杂水样进行化学耗氧量值测量,并将测量值与实验室结果进行比较,验证了该系统的可靠性.结果表明,该全光谱法水质监测系统不需要消耗任何试剂,无二次污染,测量准确度高、速度快,可广泛应用于水质化学耗氧量的实时、现场监测分析.     

Proactive data envelopment analysis: Effective production and capacity expansion in stochastic environments

Demand fluctuations that cause variations in output levels will affect a firm’s technical inefficiency. To assess this demand effect, a demand-truncated production function is developed and an “effectiveness” measure is proposed. Often a firm can adjust some input resources influencing the output level in an attempt to match demand. We propose a short-run capacity planning method, termed proactive data envelopment analysis, which quantifies the effectiveness of a firm’s production system under demand uncertainty. Using a stochastic programming DEA approach, we improve upon short-run capacity expansion planning models by accounting for the decreasing marginal benefit of inputs and estimating the expected value of effectiveness, given demand. The law of diminishing marginal returns is an important property of production function; however, constant marginal productivity is usually assumed for capacity expansion problems resulting in biased capacity estimates. Applying the proposed model in an empirical study of convenience stores in Japan demonstrates the actionable advice the model provides about the levels of variable inputs in uncertain demand environments. We conclude that the method is most suitable for characterizing production systems with perishable goods or service systems that cannot store inventories.     

Spare parts management: Linking distributional assumptions to demand classification

Spare parts are known to be associated with intermittent demand patterns and such patterns cause considerable problems with regards to forecasting and stock control due to their compound nature that renders the normality assumption invalid. Compound distributions have been used to model intermittent demand patterns; there is however a lack of theoretical analysis and little relevant empirical evidence in support of these distributions. In this paper, we conduct a detailed empirical investigation on the goodness of fit of various compound Poisson distributions and we develop a distribution-based demand classification scheme the validity of which is also assessed in empirical terms. Our empirical investigation provides evidence in support of certain demand distributions and the work described in this paper should facilitate the task of selecting such distributions in a real world spare parts inventory context. An extensive discussion on parameter estimation related difficulties in this area is also provided.     

Buyback contracts with price-dependent demands: Effects of demand uncertainty

We explore buyback contracts in a supplier–retailer supply chain where the retailer faces a price-dependent downward-sloping demand curve subject to uncertainty. Differentiated from the existing literature, this work focuses on analytically examining how the uncertainty level embedded in market demand affects the applicability of buyback contracts in supply chain management. To this end, we seek to characterize the buyback model in terms of only the demand uncertainty level (DUL). With this new research perspective, we have obtained some interesting new findings for buyback. For example, we find that (1) even though the supply chain’s efficiency will change over the DUL with a wholesale price-only contract, it will be maintained constantly at that of the corresponding deterministic demand setting with buyback, regardless of the DUL; (2) in the practice of buyback, the buyback issuer should adjust only the buyback price in reaction to different DULs while leave the wholesale price unchanged as that in the corresponding deterministic demand setting; (3) only in the demand setting with an intermediate level of the uncertainty (which is identified quantitatively in Theorem 5), buyback provision is beneficial simultaneously for the supplier, the retailer, and the supply chain system, while this is not the case in the other demand settings. This work reveals that DUL can be a critical factor affecting the applicability of supply chain contracts.     

规模企业要积极主动挑“大梁”责任

概述了中国规模企业在资本主义经济危机中的社会责任。资本主义经济危机给带来了世界市场萎缩和下滑,使我国PCB工业带来了困难和问题。我们应抓住"机遇",积极开辟国内外市场的同时,加快产品升级、转型和创新,迎接世界市场"复苏"的到来。另外,在中国共产党领导下,正在加快推进城-镇化和民生工程等的建设,提高人民生活,会快速扩大内需,减少或避免资本主义经济危机的冲击和影响。