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排序方式: 共有1606条查询结果,搜索用时 8 毫秒
71.
研究了京东板栗在不同干燥条件下的失水规律。结果表明:板栗烘干、真空干燥、微波干燥的失水特性主要表现为降速干燥过程,干燥过程属于内部扩散控制。烘干和微波干燥动力学模型为Page方程;真空干燥为单项扩散模型。不同切片厚度具有相同的变化趋势,但对干燥速率的大小影响程度却存在差异。 相似文献
72.
利用ArcGIS平台探究山东省碳排放演化格局,根据山东省各市2005年、2007年、2010年和2012年四个年份各市碳排放时空格局演化趋势,得出山东省碳排放总量未来有进一步增加的趋势。利用系统动力学构建山东省能源-经济-社会-环境(碳排放)系统动力力学模型,运用VENSIM软件平台对山东省未来经济发展情景进行定量化动态模拟,研究山东省低碳经济发展的可行方案。设置四种不同的发展情景方案,预测在不同情景方案下山东省低碳经济综合发展状况。研究结果表明,在情景Ⅳ模式下,山东省2020年经济发展规模、能源消耗量、碳排放总量、单位GDP碳排放都要优于其他三种场景下模拟出的结果,得出山东省低碳经济协调发展的最优方案,为山东省低碳经济发展和规划提供决策支持。 相似文献
73.
The primary objective for modeling of machining processes is to develop a predictive capability of machining performance in order to facilitate effective planning of machining operations. This capability leads to faster implementation, higher performance, quality at a lower cost. This comes about due to improved selection of machining parameters, optimal fixture design and the avoidance of tool failure. The simulation system presented simultaneously considers the effect of cutter geometry, the cutter's initial position errors, workpiece geometry, machine tool dynamics, and workpiece/fixture system dynamics on the machining process.The integration of all of the above in one model provides an off-line tool to simulate and optimize the machining parameters and the fixture configuration cutting both lead and production time. The modular nature of the simulation system presented allows for the study of many different machining processes. The cutting forces in this system are modeled using a mechanistic approach. NURBS curves and surfaces are utilized for the geometric modeling and simulation of the machining process. While a finite element method is used to model and analyze the workpiece/fixture dynamics. Two case studies are presented to demonstrate the practical application of the presented simulation. The first case presents the optimization of the fixture configuration of a generic automotive component. While the second case presents the results of simulations performed on a novel mill/grind machining process. This process is a combination of face milling and grinding in one operation. Some simulated results are presented along with experimental validation. 相似文献
74.
Sonia Martinez Antoni Aguilo Lluis Rodas Leticia Lozano Carlos Moreno 《Journal of sports sciences》2018,36(3):333-339
Adequate dietary strategies are essential for the successful participation in ultra-endurance races. The aim of this study was to evaluate and compare the energy and water intakes of participants during three different mountain ultra-endurance runs. The study took place at the “Ultra Mallorca Serra de Tramuntana” (Mallorca, Spain), an ultra-endurance mountain event with runners participating either in a 44-km (Marathon, n = 51), a 67-km (Trail, n = 109) or a 112-km (Ultra, n = 53) run competition. Participants in the study answered a questionnaire focused on the nutritional intake within an hour after finishing the competition. Mean energy intake during the competitions was 183 kcal · h¯1, with an average carbohydrate intake of 31 g · h¯1 (52.1% of participants consumed less than 30 g · h¯1). No significant differences between competitions were found in these parameters. However, a higher percentage of energy from lipids in participants in the Trail and the Ultra was found (P = 0.034). Furthermore, significant differences were observed in water intake per hour of competition (P = 0.039), with the lowest value for the intake during the Ultra competition. In conclusion, the majority of the participants in the study present low carbohydrate intakes. However, fluid intake seems to be adequate. Different distances did not significantly influence the participants’ nutritional strategies. 相似文献
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利用Lyapunov函数研究了带有免疫反应及非线性传染项βV^qT^p(q≤1)的病毒动力学模型的全局稳定性. 相似文献
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