Design-balanced capacitated multicommodity network design with heterogeneous assets

Management of assets plays an essential role in determination of service plans operated by carriers in the transportation and logistics system. In this paper, we introduce certain issues related to management of heterogeneous assets in the well-known design-balanced capacitated multicommodity network design, where design-balanced requirements are explicitly defined based on heterogeneous assets.Taking vehicles as an example of heterogeneous assets, we first present an arc-based formulation for the proposed problem and discuss two associated subproblems. We then propose a tabu search based metaheuristic for this problem. Over a wide range of network design instances, we respectively compare our approach with CPLEX with one-hour and ten-hour time limits. Computational results demonstrate that the proposed approach performs very well in terms of solution quality and computing time, especially for large instances.     

Structural constraints and excess capacity: an international comparison of manufacturing firms

Excess capacity results in real and opportunity costs as well as lower factor productivity. Conventionally, variation in capacity utilisation rates has been explained with reference to the business cycles and market imperfections. In this article, we show that these two factors do not always fully explain the causes of idle capacity. Our findings suggest that manufacturing firms in low‐income countries tend to have lower capacity utilisation (CU) rates than those in middle‐ and upper‐middle‐income groups. To explain this peculiarity, it is proposed in this article that the level of excess capacity partly depends on supply‐side conditions and institutional variables. The findings provide strong support for this view and suggest that there are gains to be made in the manufacturing industries of the lower‐income countries through improvements in the structural conditions.     

伊迪丝·华顿在《纯真年代》中对人性的理解

伊迪丝·华顿是美国文学史上最具影响力的女性作家之一,她的作品体裁广泛,尤以小说见长.其中《纯真年代》是最具代表性的一部.通过分析华顿对几位主人公的细致刻画和描写来探寻她在这部小说中对人性的理解,认为其理解具有明显的矛盾性和局限性.这些在三位主人公身上有着很好的体现.纽兰·阿切尔是一个勇敢的懦夫和理想主义者；梅·伟兰是一个复杂的社会产物,貌似单纯无知的外表下深藏心机；艾伦·奥兰斯卡是一个对社会传统的温和的反派人物,神秘、勇敢、崇尚自由却最终只能向传统低头.这与当时的社会背景以及她本人的人生经历是密不可分的.     

Partial central subspace and sliced average variance estimation

Sliced average variance estimation is one of many methods for estimating the central subspace. It was shown to be more comprehensive than sliced inverse regression in the sense that it consistently estimates the central subspace under mild conditions while slice inverse regression may estimate only a proper subset of the central subspace. In this paper we extend this method to regressions with qualitative predictors. We also provide tests of dimension and a marginal coordinate hypothesis test. We apply the method to a data set concerning lakes infested by Eurasian Watermilfoil, and compare this new method to the partial inverse regression estimator.     

Estimation of partially linear single-index additive hazards model with current status data

In this paper, we introduce a partially linear single-index additive hazards model with current status data. Both the unknown link function of the single-index term and the cumulative baseline hazard function are approximated by B-splines under a monotonicity constraint on the latter. The sieve method is applied to estimate the nonparametric and parametric components simultaneously. We show that, when the nonparametric link function is an exact B-spline, the resultant estimator of regression parameter vector is asymptotically normal and achieves the semiparametric information bound and the rate of convergence of the estimator for the cumulative baseline hazard function is optimal. Simulation studies are presented to examine the finite sample performance of the proposed estimation method. For illustration, we apply the method to a clinical dataset with current status outcome.     

Looking Upstream: Optimal Policies for a Class of Capacitated Multi‐Stage Inventory Systems

We consider a multi‐stage inventory system with stochastic demand and processing capacity constraints at each stage, for both finite‐horizon and infinite‐horizon, discounted‐cost settings. For a class of such systems characterized by having the smallest capacity at the most downstream stage and system utilization above a certain threshold, we identify the structure of the optimal policy, which represents a novel variation of the order‐up‐to policy. We find the explicit functional form of the optimal order‐up‐to levels, and show that they depend (only) on upstream echelon inventories. We establish that, above the threshold utilization, this optimal policy achieves the decomposition of the multidimensional objective cost function for the system into a sum of single‐dimensional convex functions. This decomposition eliminates the curse of dimensionality and allows us to numerically solve the problem. We provide a fast algorithm to determine a (tight) upper bound on this threshold utilization for capacity‐constrained inventory problems with an arbitrary number of stages. We make use of this algorithm to quantify upper bounds on the threshold utilization for three‐, four‐, and five‐stage capacitated systems over a range of model parameters, and discuss insights that emerge.     

Nonparametric causal effects based on marginal structural models

A parametric marginal structural model (PMSM) approach to Causal Inference has been favored since the introduction of MSMs by Robins [1998a. Marginal structural models. In: 1997 Proceedings of the American Statistical Association. American Statistical Association, Alexandria, VA, pp. 1–10]. We propose an alternative, nonparametric MSM (NPMSM) approach that extends the definition of causal parameters of interest and causal effects. This approach is appealing in practice as it does not require correct specification of a parametric model but instead relies on a working model which can be willingly misspecified. We propose a methodology for longitudinal data to generate and estimate so-called NPMSM parameters describing so-called nonparametric causal effects and provide insight on how to interpret these parameters causally in practice. Results are illustrated with a point treatment simulation study. The proposed NPMSM approach to Causal Inference is compared to the more typical PMSM approach and we contribute to the general understanding of PMSM estimation by addressing the issue of PMSM misspecification.     

再论过去分词形容词的语用制约

制约是一种对语言使用产生某种限制或规约的语言运作机制。“语用制约”是指HN（名词中心词）与其前置修饰语之间在使用过程中形成的互动和限制。纵聚合语义信息制约要求APP（过去分词式形容词）必须能刻画出HN所指的超越典型的区分性特征和非常状态。最简结构制约要求APP＋HN实现语符数最小化，同时达到所承载的语义信息量最大化。从属性上看，纵聚合语义信息制约为语义性制约；而最简结构制约则为结构性制约。     

西部水电开发的生态制约与对策

水电资源开发对生态环境的影响，既有积极一面，又有消极一面。从总体上说，大型水坝给有关生态系统，特别是物种所造成的影响往往是负面多于正面。西部水电建设进入了一个与过去的技术、资金、市场机制制约完全不同的阶段——生态制约阶段。鉴于水电开发已经面临生态之忧，应当适当调整开发政策，采取相应对策，以便加强开发中的生态保护。     

边缘贫困群体的形成原因及扶助对策——以江苏省南京市为例

边缘贫困群体是一个新出现的困难群体.结合江苏省南京市的具体情况,分析了这一群体形成的主要原因,认为"低保"标准偏低、界定的单一化、就业不稳定以及政府缺乏专业工作人员,是这一群体形成的主要原因.探讨了针对边缘贫困群体的4点扶助对策,即推行"发展性社会政策"、实行差别救助、积极发挥社区援助功效以及强化非正式社会支持网络.