军用飞行汽车设计研究

随着科学技术的发展,我国已出现多种样式的飞行汽车,但对飞行汽车发展现状的分析表明,我国自主研发的军用飞行汽车仍然相对缺乏、因此,开展对军用飞行汽车的设计研究具有重要意义在研究飞行汽车历史及现状的基础上,考虑了驾驶方式、重心等方面的问题,分析了军用飞行汽车未来发展趋势在技术方面,主要对军用飞行汽车的外部造型进行了设计,为后续设计提供了参考     

闽南红砖在现代室内空间中的表征与应用

从泉州所用闽南红砖的地方性表征与建筑的在地文化,浅谈红砖文化在室内空间设计中的可创造性和可复制性.文章从室内运用现状和材料特性方面探讨闽南红砖材质与尺寸在室内空间设计中的构成法则.     

ODS 反相键合相色谱柱的使用、维护

本文对ODS反相键合相色谱分析的核心部分——ODS色谱柱的使用、保存、维修及再生等方面的经验和技术作了详细的介绍,并总结了包括ODS柱在内的有关液相色谱柱的异常现象及原因一表,以利故障的查寻和排除。     

关停小火电厂址资源再利用规划设计浅谈

电力建设实施"上大压小",是电力工业落实国务院节能减排目标的关键工作,也是电力工业走资源节约型、环境友好型和构建和谐社会的重要举措.但随着大批小火电的关停,如何再利用老厂土地和既有设施资源建设大容量、高参数机组,是摆在总图运输设计工作者面前的一道难题.作者针对现有小机组电厂的现状条件,提出了在关停小机组场地上建设大机组的规划设计思路,希望与同行交流.     

压铸模使用寿命与优化压铸过程控制

分析了压铸过程中模具的热疲劳失效机理及其影响因素,讨论了优化压铸过程控制对模具寿命的影响.     

高温高压管道焊接坡口选择及焊条用量计算

从经济和技术角度分析火电厂高温高压管道焊缝宜采用的坡口形式,并对各种坡口形式的焊条用量估算推导出经验公式.     

型材挤压模工作带长度设计计算的数学建模

本文采用有限元方法 ,以型材挤压过程的有限元模拟为基础 ,研究了局部挤压比、挤压带面积和模孔距离对金属流动速度的影响 ,获得了型材挤压过程的变形流动规律。并综合主要模具结构参数对金属流动速度的影响 ,建立了铝型材挤压模模孔工作带设计计算的数学模型。选择实际型材零件按本文推导的公式设计了工作带长度 ,并与实验进行了验证 ,结果表明挤压效果良好。该公式可用于铝型材挤压模工作带长度设计计算     

Do Management Actions to Restore Rare Habitat Benefit Native Fish Conservation? Distribution of Juvenile Native Fish Among Shoreline Habitats of the Colorado River

Many management actions in aquatic ecosystems are directed at restoring or improving specific habitats to benefit fish populations. In the Grand Canyon reach of the Colorado River, experimental flow operations as part of the Glen Canyon Dam Adaptive Management Program have been designed to restore sandbars and associated backwater habitats. Backwaters can have warmer water temperatures than other habitats, and native fish, including the federally endangered humpback chub Gila cypha, are frequently observed in backwaters, leading to a common perception that this habitat is critical for juvenile native fish conservation. However, it is unknown how fish densities in backwaters compare with that in other habitats or what proportion of juvenile fish populations reside in backwaters. Here, we develop and fit multi‐species hierarchical models to estimate habitat‐specific abundances and densities of juvenile humpback chub, bluehead sucker Catostomus discobolus, flannelmouth sucker Catostomus latipinnis and speckled dace Rhinichthys osculus in a portion of the Colorado River. Densities of all four native fish were greatest in backwater habitats in 2009 and 2010. However, backwaters are rare and ephemeral habitats, so they contain only a small portion of the overall population. For example, the total abundance of juvenile humpback chub in this study was much higher in talus than in backwater habitats. Moreover, when we extrapolated relative densities based on estimates of backwater prevalence directly after a controlled flood, the majority of juvenile humpback chub were still found outside of backwaters. This suggests that the role of controlled floods in influencing native fish population trends may be limited in this section of the Colorado River. Copyright © 2014 John Wiley & Sons, Ltd.     

Agro-ecosystem modeling can aid in the optimization of biomass feedstock supply

Recent European Directives promoted the development of biofuels, requesting mandatory limits to their emissions ot greenhouse gases (GHG). Second-generation biofuels based on lignocellulosic biomass are prime candidates but their GHG emissions are variable and uncertain. Agro-ecosystem modeling can capture them and the performance of biofuel feedstocks.This study aimed at optimizing feedstock supply for a bioethanol unit in France, from agricultural residues, annual and perennial crops. Their productivity and environmental impacts were modelled on a regional scale using geo-referenced data on soil properties, crop management, land-use and future weather data. Several supply scenarios were tested. Cereal straw was the most efficient feedstock but had a low availability, and only miscanthus could meet the bioethanol plant's demand. Sorghum combined poor yields and high GHG emissions compared by miscanthus and triticale. A mix of three biomass sources used less than 3% of the regional agricultural land while abating GHG emissions by 60%.     

农田资源优化分配的计算机仿真

对于既定面积的农田资源,为使所产作物较能针对市场需求,并使种植经济效益最大化,需合理分配不同作物的种植面积.通过分析不同作物的种植成本,存贮成本,结合作物的收成与销售价格,获得各作物的种植经济效益对于种植面积的非线性关系,建立相应的计算机仿真数学模型.为了有效预测来年的作物收成和销售价格,简化假定来年的种植计划不影响来年的销售价格,根据往年的统计数据得到有关的预测数据.对资源分配问题用遗传算法进行优化求解,得到使净收益最大化的种植田亩分配方案结果.分析结论表明,最大经济效益对应的种植面积分配方案有一定的选择范围,更合理的种植面积分配方案必须面向市场需求.