Capacity investment decisions under risk aversion

This article studies the optimal capacity investment problem for a risk‐averse decision maker. The capacity can be either purchased or salvaged, whereas both involve a fixed cost and a proportional cost/revenue. We incorporate risk preference and use a consumption model to capture the decision maker's risk sensitivity in a multiperiod capacity investment model. We show that, in each period, capacity and consumption decisions can be separately determined. In addition, we characterize the structure of the optimal capacity strategy. When the parameters are stationary, we present certain conditions under which the optimal capacity strategy could be easily characterized by a static two‐sided (s, S) policy, whereby, the capacity is determined only at the beginning of period one, and held constant during the entire planning horizon. It is purchased up to B when the initial capacity is below b, salvaged down to Σ when it is above σ, and remains constant otherwise. Numerical tests are presented to investigate the impact of demand volatility on the optimal capacity strategy. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 218–235, 2016     

曲面拟合法和梯度法相结合的图像亚像素配准算法

针对传统亚像素配准算法存在精度不高、计算复杂的问题,提出了一种曲面拟合法和梯度法相结合的图像亚像素配准算法。采用9点相关系数曲面拟合法对图像进行粗配准,求得一个相对粗略的亚像素配准位置;在两幅图像中选取相同尺寸的子区图像,在粗略的亚像素配准位置基础上,采用梯度法最终获得精确的亚像素配准位置。不同平移关系下的样本图像亚像素配准对比实验结果表明,该算法实现了曲面拟合法和梯度法的优势互补,有效提高了图像配准的精度,最大配准绝对误差由0.17像素降低为0.02像素。     

NICALON SiC/Al 预制丝热膨胀特性研究

本文研究了NICALON SiC束丝纤维增强铝预制丝在15～400℃温度区间内的热膨胀特性。研究表明预制丝两次热循环后得到的膨胀曲线不一致,该曲线在15～400℃范围的平均热膨胀系数分别为3.2×10~(-6)℃~(-1)、4.1×10~(-6)℃~(-1)。本文对预制丝的热膨胀行为进行了理论分析和探讨,计算值和实验值较为符合。     

多维六角形节块动力学程序系统的开发及验证

以多维六角形节块中子动力学程序HENKO的理论模型为基础,研制成功六角形组件的反应堆多维瞬态分析程序系统,提出了一种处理控制棒尖点问题的方法.通过VVER一号国际基准问题的验算,验证了本程序的正确性.     

KCl 和KBr 晶体热膨胀系数的计算

本文利用Gordon-Kim 模型给出的离子间相互作用势,计算了KCl 和KBr 晶体在室温下的热膨胀系数。所得的结果与实验值进行了对照。     

高双折射光子晶体光纤用于温度传感的研究

文中分析了高双折射光子晶体光纤用于温度传感的应用。在高双折射光子晶体光纤的特定空气孔中填充折射率温度系数高的液体材料,温度的变化会导致光纤传输特性的变化,通过检测其双折射的变化从而实现温度传感。文中运用平面波扩展法计算分析了该新型光子晶体光纤的双折射特性随温度变化的关系。     

脉冲工况晶闸管扩展速度的影响因素研究

为研究不同因素对其电流扩展速度的影响,根据晶闸管的结构特点和工作原理,建立晶闸管器件模型及脉冲成形网络等效电路模型并进行了仿真模拟.数值仿真结果表明,当正向阻断电压从3000 V增加至5000 V时,扩展速度可增加24.6％;当基区宽度从500μm增加至900μm时,扩展速度降低了31.7％;当载流子寿命从1μs增加至...     

Expansion planning for waste‐to‐energy systems using waste forecast prediction sets

We consider an expansion planning problem for Waste‐to‐Energy (WtE) systems facing uncertainty in future waste supplies. The WtE expansion plans are regarded as strategic, long term decisions, while the waste distribution and treatment are medium to short term operational decisions which can adapt to the actual waste collected. We propose a prediction set uncertainty model which integrates a set of waste generation forecasts and is constructed based on user‐specified levels of forecasting errors. Next, we use the prediction sets for WtE expansion scenario analysis. More specifically, for a given WtE expansion plan, the guaranteed net present value (NPV) is evaluated by computing an extreme value forecast trajectory of future waste generation from the prediction set that minimizes the maximum NPV of the WtE project. This problem is essentially a multiple stage min‐max dynamic optimization problem. By exploiting the structure of the WtE problem, we show this is equivalent to a simpler min‐max optimization problem, which can be further transformed into a single mixed‐integer linear program. Furthermore, we extend the model to optimize the guaranteed NPV by searching over the set of all feasible expansion scenarios, and show that this can be solved by an exact cutting plane approach. We also propose a heuristic based on a constant proportion distribution rule for the WtE expansion optimization model, which reduces the problem into a moderate size mixed‐integer program. Finally, our computational studies demonstrate that our proposed expansion model solutions are very stable and competitive in performance compared to scenario tree approaches. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 47–70, 2016     

一类带容量限制的运输问题

考虑一类带容量限制的运输问题.采用构造辅助网络的方法,将运输网络中的每个配送中心均拆分成两个节点,构造出新弧,形成新的网络,把此类运输问题转换为最小费用流问题来解决.并在此基础上,考虑运输网络中配送中心的容量扩张问题.     

一类带配送中心运输问题的容量扩张模型研究

运输问题一般采用表上作业法来解决,考虑一类带配送中心的运输问题,若仍采用表上作业法,会使问题复杂化.文中采用一种构造辅助网络的方法:在运输网络中将每个配送中心均拆分成两个点,连接两点形成新弧,构造出新的网络,并给每条弧赋予参数,将此类运输问题转换为最小费用流模型来解决,可以使问题模型和运算简单化.在此基础上,考虑运输网络中配送中心和边的容量扩张问题.