供应链环境下供求双方面临的约束参数对产品质量的影响

供应链环境下一种产品的质量与供应商、生产商各自的质量策略选择有关。为了保证最终产品的质量,供求双方在供应合同中往往会设定一些人为的约束来保证各自的利益。同时,他们也会面临一些客观的自然约束。在这些约束下,各个约束参数的大小以及变化对供求双方的策略选择以及最终产品的质量都会构成影响。文章建立博弈模型来分析这种影响,并且给出相应的解决办法。     

Farmers' knowledge and perceptions of soil erosion and conservation measures in the Central Highlands,Kenya

A lack of appreciation of Kenyan farmers' knowledge and their perceptions of soil erosion and soil conservation measures was the reason for low adoption of recommended technologies. This research was carried out to identify the criteria that farmers used to distinguish farm‐types and to use these types to evaluate different knowledge levels and perceptions of soil erosion and existing soil and water conservation (SWC) measures in the Central Highlands of Kenya. Community meetings and semi‐structured household surveys were carried out in a small catchment, with 120 households. Results partly support the idea of using farmer‐developed criteria to distinguish among land managers with reference to a farm‐type classification. Criteria distinguishing three classes of land managers (good, moderate and poor) were significant with regard to the following land husbandry practices: use of hybrid or recycled seed and use of organic and/or inorganic fertilizers. Farmers were aware of on‐going soil erosion and of several erosion control measures. Whereas a majority of farmers preferred grass‐strips as a SWC measures, they did not recognize agroforestry as a form of SWC measure. Farmers perceived that SWC measures could successfully increase crop yields and soil‐water retention, and increase land value. In general, farmers did not perceive that SWC measures successfully prevented erosion phenomena, given the evidence of on‐site erosion indicators. They attributed the continued erosion to high rainfall, steep slopes, lack of maintenance and poorly designed SWC measures. They did not consider poor soil‐cover, up‐down tillage and tall trees to be the causes of erosion. Farmers faced several constraints in adopting SWC measures: lack of labour, tools, capital and know‐how to construct the measures. Copyright © 2005 John Wiley & Sons, Ltd.     

一非线性混合整数规划问题

对一有界约束非线性混合整数规划问题进行了研究。通过对该问题性质的分析,把它变成了一个等价的,易求解的纯整数规划问题,并给出了原问题相应的算法。     

Hybrid rice achievements,development and prospect in China

This article reviews the history and progress of hybrid rice development. Hybrid rice research was initiated back in 1964, and commercialized in 1976. Three-line and two-line system hybrid rice were developed in 1974 and 1995, respectively. Research on super hybrid rice, which was first launched by Ministry of Agriculture, China in 1996, is discussed, and the great progress of super hybrid rice had been achieved with a new yield record by 15.4 t ha–1 in the 6.84 ha demonstration location in Xupu, Hunan Province, China in 2014. And the mechanism of heterosis, the techniques of hybrid seed production and the modern field managements in hybrid rice over the past decades are also discussed. Additionally, this article dealt with the intellectual property protection(IPR) and development of hybrid rice seed industry in China. Major factors that constrain hybrid rice development are analyzed and possible solutions to this problems are proposed. Finally, the authors present methods to further increase production yield, and propose an improvement for breeding super high-yielding hybrid rice based on these methods.     

不同约束值变化对输油管道优化运行的影响

在提出结蜡处理方法的基础上，探讨了管壁结蜡及主要约束条件值变化对输油管道优化运行的影响，同时，又提出了结蜡危险区的概念，分析了管道承压能力与出站节流损失的关系。结果表明，由于结蜡、管道承压、进站压力、末站进站油温及泵特性等约束条件值不同，优化方案也不同。合理确定相关约束条件值对优化结果的实用性、安全性及经济性具有重要意义。在结蜡及管道低承压情况下，末站油温的确定尤应慎重，否则有可能形成末段瓶颈，影响管道的正常运行。     

线性支持向量分类机优化问题解的二阶充分条件

优化问题的二阶充分条件是研究灵敏度分析的基础,支持向量机是数据挖掘的新方法。针对线性支持向量分类机优化问题,研究了其解的二阶充分条件,给出了二阶充分条件成立的假设条件。研究表明,该假设条件很弱,用支持向量机算法求解实际问题时,通常假定这一条件成立,特别地,对线性可分支持向量分类机优化问题,其解一定满足这一条件,满足二阶充分条件成为当然成立的事实。     

基于混合并行遗传算法的多目标约束优化技术研究

多目标约束优化问题属于NP问题。并行遗传算法是解决该类问题的常用算法,它具有较强的全局搜索能力和并行性,但局部搜索能力差,禁忌搜索算法则比较适合于局部搜索。提出了一种基于混合并行遗传算法的多目标约束优化方法,该方法综合了并行遗传算法和禁忌搜索算法的优势,改进了并行遗传算法的性能,能有效避免局部最优解。     

二维工程图形中相切关系分析及计算机编码方法

相切约束从位置关系上来说是一种较复杂的约束，多数相切约束存在多解情况，从多解中确定出和原来图形相符的解是图形参数化系统能否正确进行尺寸驱动的关键。为此，在深入研究二维工程图形中常见相切位置关系的基础上，结合矢量叉积的概念，给出了一种确定图元相切位置关系的方法。     

Perceptual constraints on stream fish habitat selection: effects of food availability and water velocity

Abstract– Habitat selection theory assumes that individuals either know the quality of habitats a priori or can learn it through experience. This work tests the effects of total food supply and of water velocity on the ability of drift-feeding stream fish ( Rhinicthys atratulus ) to discriminate between two patches in a laboratory flow-tank that differ only in the amount of food in the patch. If the fish can discriminate between the patches, their distributions should be predicted by ideal free distribution models; otherwise, their distributions should be random. The results show that at high total food supply levels, fish distributions differ from random in general agreement with ideal free distribution models; total food supply decreases, fish distributions become random, indicating that total food supply levels affect the ability of fish to discriminate between habitats that differ only in food supply. Increased water velocity was expected to affect fish distributions similarly, but its effect was not significant. The results suggest that habitat selection theory should consider both differences between habitats and the ability of fish to perceive those differences.     

港航城市之竞合关系及其法律规制——以上海建设国际航运中心为切入点

长三角区域内外各大港航城市在合作与竞争问题上已经展开并将长期存在一系列博弈,但是这种博弈目前还处于低效和失范状态。这很大程度上源于背后的内在体制冲突、地方政府的盲目绩效冲动以及立法的缺失和滞后,需要《中华人民共和国宪法》、《中华人民共和国立法法》、《中华人民共和国反垄断法》对其做出一一回应。通过有效的法律规制引导合作向深度发展,变对抗的竞争为合作的竞争,确保港航城市合作与竞争在法制统一原则下进行,才能够最大程度地在良性竞合关系中实现国际竞争力的提高,并推动区域内外经济的协调发展和全国性统一大市场的形成和完善。