基于Xilinx FPGA DCM的研究与设计

为了使FPGA时钟在控制方面的设计更加简洁,介绍了一种基于Xilinx FPGA数字时钟的设计方法：数字时钟管理器（DCM）。对其工作原理、组成、使用方法及应用进行了系统描述,通过对DCM IP核的参数设置和程序设计实现了精准的倍频、分频和相位移动等功能,并在ISE13.1的开发环境下对其分别进行仿真,给出对应的清晰的仿真波形。用户可以根据实际设计的需要控制时钟完成任意的倍频和分频及相位移动,其操作简单、应用灵活,方便移植到其他应用中。     

Railcar reallocation optimization on water-rail network under uncertain busyness

Water-rail intermodal transportation can reduce cargo losses and transportation transferring costs. However, the imbalance between the capacity of the scheduled railway network and the large container freight demand greatly reduces operational efficiency. To minimize the total transportation cost and relocation cost, a railcar reallocation stochastic optimization model is formulated to deal with uncertain congestion in the railway network. To capture the uncertain busyness and queuing pattern, a hypercube spatial queue model is embedded in the optimization model by estimating the expected queue length and waiting time. To solve the proposed nonlinear nonconcave stochastic model, an approximate hypercube based iterative algorithm is proposed. A real-world case study is presented to show the effectiveness and efficiency of the proposed method. The proposed model outperforms the comparable deterministic model in the objective value. Sensitivity analyses on the ratio of the unit waiting cost and the unit travel cost for empty cars, and the total number of freight cars show the robustness of the proposed method.     

面向嵌入式系统绿色需求的数据分配方法

能耗和资源等绿色需求是嵌入式系统发展不容忽视的因素.数据分配作为编译后端的重要优化手段,对能耗以及资源的利用率有着重要影响.为提高资源和能源的有效利用率,构建了数据分配过程的绿色评估模型,并以此为指导,提出了一种迭代式多目标分配优化方法,从能源消耗和资源的均衡使用度2个方面出发,利用可交换类指令重排优化和寄存器重分配优化,对总线和存储系统的绿色指标进行改进.模拟实验表明,该方法相对于GCC编译器,能够获得23%左右的绿色指标提升值,为满足更高的绿色需求提供了保障.     

清单计价模式下施工合同风险再分担路径研究

通过分析2013版清单计价规范对风险分担的规定,以及因契约不完备性引致的基于风险再分担的各种履约机制的讨论,在施工合同中设置相应的适应性条款,并嵌入未来状态补偿的风险再分担方案,可形成清单计价模式下的基于风险再分担的合同适应性条款策略集。该思路是实现合同优化的重要方式,有助于控制投资失控的风险,提高项目管理绩效。     

基于SFA分析我国工业增长的资源再配置效应

生产要素流动和再配置对提高生产率、促进经济增长具有重要作用。根据1998-2007年面板数据,采用随机前沿法,测算我国工业的全要素生产率增长率,借助赛尔奎因的资源再配置效应模型,分析我国工业增长的资源再配置效应。分析发现：该时段我国工业部门间的资源再配置效应为负,资本、劳动在工业部门间的转移并没有导致部门间再配置效应的提高;由于资本和劳动,特别是劳动,在地区间的再配置趋于不合理,从而导致地区间的资源再配置效应不高;总体上,我国工业增长格局的转换速度与资源在部门间和地区间再配置的转换速度并不协调,从而引起部门间和地区间的再配置效应不佳,我国工业增长的资源再配置效应有待改进。     

Evaluating the role of resilience in reducing economic losses from disasters: A multi-regional analysis of a seaport disruption

Models to estimate economic impacts of disasters have recently been augmented to include resilience. However, most research has incorporated only a limited set of resilience tactics and has not estimated their individual loss reduction effect. We present a comprehensive framework for estimating the relative effects of a broad set of post-disaster resilience tactics. Our methodological innovation is illustrated by adapting the TERM multi-regional CGE model for a seaport disruption, distinguishing inherent resilience working through the price system from adaptive resilience and other inherent tactics to cope with input shortages. We also overcome a path-dependency problem in the modelling process.     

基于FlexSim 的军队自动化立体仓库货位优化研究

为提高军队自动化立体仓库出货速度和运行稳定性,提出了在堆垛机闲时对货位进行以分类存储L 形分区为导向的再分配优化设计。根据用户需求,程序自动生成分类存储的L 形分类存储货位分区信息,并调用堆垛机对在存货品逐一判断、搬运,让所有货品按照L 形区域排列,完成货位优化。利用FlexSim 软件对具体实例进行了仿真,结果表明,优化后的货位能较大程度地提高仓库的输出效率。     

Modelling and a tabu search solution for the slab reallocation problem in the steel industry

This paper considers a slab reallocation problem arising from operations planning in the steel industry. The problem involves reallocating steel slabs to customer orders to improve the utilisation of slabs and the level of customer satisfaction. It can be viewed as an extension of a multiple knapsack problem. We firstly formulate the problem as an integer nonlinear programming (INLP) model. With variable replacement, the INLP model is then transformed into a mixed integer linear programming (MILP) model, which can be solved to optimality by MILP optimisers for very small instances. To obtain satisfactory solutions efficiently for practical-sized instances, a heuristic algorithm based on tabu search (TS) is proposed. The algorithm employs multiple neighbourhoods including swap, insertion and ejection chain in local search, and adopts solution space decomposition to speed up computation. In the ejection chain neighbourhood, a new and more effective search method is also proposed to take advantage of the structural properties of the problem. Computational experiments on real data from an advanced iron and steel company in China show that the algorithm generates very good results within a short time. Based on the model and solution approach, a decision support system has been developed and implemented in the company.     

Improving Wheat Productivity in Pakistan: Econometric Analysis Using Panel Data from Chaj in the Upper Indus Basin

Abstract

Increasing water scarcity, degradation of land and water resources, continuing low agricultural productivity, and increasing populations are posing the largest ever challenges for development of agricultural economies in many developing countries including Pakistan. Using panel data from irrigated settings in Chaj sub-basin of the Indus basin in Pakistani Punjab, we attempt to: (a) analyze the causes of low productivity; (b) disentangle factors (both land, water and other factors) contributing to productivity variations; and (c) identify limits and opportunities for narrowing productivity gaps and increasing overall wheat production, with a view to enhance food security for the poor. The results of the study indicate that locational inequities in distribution of canal water, use of groundwater of varying quality, differences in use of seed varieties, and other inputs lead to significant variations in wheat productivity. Key implications are that large gains in wheat productivity are possible by (a) improving the production environment at the tail-end through integrated water management practices; (b) adjusting the mix of canal and groundwater use; and (c) using technological interventions to improve the adoption of modern wheat varieties and dissemination of knowledge on planting dates and timings and application rates of inputs, especially water and fertilizer. Not only such interventions are economically, financially, and environmentally desirable, they are also pro-poor. What is needed is a strong political will and commitment.     

Evolution of Water Planning in New Mexico and Implications for Transboundary Groundwater Allocation

Abstract

Before 1983, the market allocated water in New Mexico under the prior-appropriation system; we prohibited export of groundwater to other states. We found, however, that the simple prohibition is unconstitutional, and that water can be withheld only if shown to be needed for the “public welfare.” Water planning began in 1987, to determine which waters (perhaps all) would be needed during the next 40 years. It has become clear that water planning has another value —the reconciliation of future supply with expected demands—which may provide more orderly reallocation than the market would, especially for aesthetic and environmental water uses that are not directly represented in the market. Our water planning seems to be supplanting the legal processes with negotiation, and to be shifting the emphasis from administration of water rights to management of real water. Diverse water-use interests within the planning regions in New Mexico are learning to negotiate their future water-management, and the 16 regions are beginning to interact with each other toward the same end. A strictly technical “wet-water” management plan that shows how the needs of all interests can be best met with the water and the capital available, and at least temporarily setting aside the legal issues, seems to be the best foundation for negotiation. The tentative settlement of a long, unfruitful legal struggle over the Pecos River is a case in point. The same principal seems promising for dealing with transboundary groundwater allocation on a larger scale.