RESEARCH ON THE DYNAMIC MATHEMATICAL MODEL OF REHEATING FURNACE

Introduction　　With the increasing global competition amongsteel companies,the enhancement of productivityof the process has become an essential task to sur-vive and succeed in the world trade market.Due tothe energy consumption of furnaces accounting fora large percent in steel plants,it has been a trendto improve the heating quality of slab in the fur-nace and reduce the energy consumption as can aspossible. Owing to:(a) the many different typesof slabs to be processed,(b) the strong intera…     

一种新型船模水动力性能测试装置研究

目前,国内外的船模水动力性能测试装置均为平面运动机构,使得船舶水动力导数的测量范围有限,而一种新型船模水动力性能测试装置,即六自由度船模水动力性能测试装置可以扩大这一测量范围.从六自由度平台的工作原理,六分力天平量程的确定和测试装置总体设计3个方面来具体研究和设计六自由度船模水动力性能测试装置.首先具体介绍六自由度平台的工作原理,即平台6根运动杆的运动与船舶六自由度运动的对应关系;然后建立船舶六自由度运动所受力和力矩的初步计算公式,以国内外平面运动机构的具体技术性能指标为依据,确定试验装置中的六分力天平的量程;最后确定测验装置的整体设计,设计出现有船池拖车平台的具体形状与尺寸.以此为依据,综合考虑拖车平台的受力情况及拖车架和六自由度平台的安装方式,确定拖车架的具体结构形式与尺寸大小,得到三维示意图、二维安装图与尺寸图,进行结构强度分析.     

燃烧室外冷却热防护数值模拟研究

本文建立了夹套式外冷却燃气发生器燃烧室热防护的CFD数值模拟模型,并用该模型对影响热防护效果的各因素进行了研究。用有限容积法离散二维轴对称N-S方程,用标准k-ε模型模拟湍流,用可压缩耦合求解器求解控制方程。研究了燃烧室内壁材料热导率、燃烧室内壁壁厚以及冷却水流量对热防护效果的影响。结果表明材料热导率对热防护效果的影响较大,高热导率的材料能够明显降低燃烧室内壁壁温和温度梯度;当燃烧室内壁为高热导率材料时,壁厚和冷却水流量对热防护效果的影响相对较小。     

Elemental composition, biochemical composition and caloric value of Antarctic krill.: Implications in Energetics and carbon balances

Samples of Antarctic krill were analyzed for elemental composition, biochemical composition, weight and caloric content. Sexes and maturity stages were separated. Mature females showed the highest caloric values (Joules) and juveniles the lowest in a per animal basis. On unit of wet weight per animal basis, spent females showed the lowest caloric values. For the caloric values by animal, a significant difference was found between males, mature females, spent females and juveniles, either on a per animal basis or in the basis of 1 g of wet weight, showing a real difference between the groups, regardless of their individual size. Significant differences were found for carbon, nitrogen and lipids, but not for proteins, analyzed in % of dry weight. Carbon was lowest for spent females and highest for mature females. On the contrary, nitrogen values were lowest for mature females and highest for males. Mature females had the highest lipid content and males the lowest. All variables were significantly correlated. For the linear regression analysis, the best correlation found was between Joules and carbon, followed by carbon vs. dry weight and Joules vs. dry weight. In an analysis with two independent variables, the best correlation was found for Joules vs. lipids and dry weight, followed by Joules vs. carbon and nitrogen, and Joules vs. lipids and proteins. The results obtained were used to make an analysis of the energy and carbon fluxes through the food chain in the sampled area, showing higher energetic and carbon “densities” in frontal areas, the POM calorific values showed an opposite pattern than that of krill.     

扭矩标准装置优化设计研究

文章介绍了通过优化设计研制成功的高准确度2kN·m扭矩标准装置的结构、特点和关键技术.该装置采用传统的静重平衡式结构,对力臂杠杆、刀口支承和砝码等进行了优化,并采用了自动加载、对中调整、对偶平衡以及PLC控制程序等技术,使该装置的校准可信度和准确度都有所提高.     

运输船电力负荷计算探讨

文章对电力负荷计算的计算方法、计算工况、设备本身功率的选取、计算表中涉及的相关系数的确定等四个方面的问题进行探讨,分别阐述了它们对电站配置的重要影响,并提出了合理配置电站的基本思考原则。     

基于系统规划的公路桥收费策略

在我国有公路桥的城市很多,为此制定相应的基于系统最优的公路桥收费策略,不仅可以方便居民的正常出行,还有助于政府利用桥梁收费达到城市交通平衡和解决市政桥梁建设资金问题的双重目的。     

基于两级温差发电的船舶废热回收试验研究

对于船舶柴油机而言,其所做功的30%都以废热的形式随尾气排放到了大气中。利用温差发电(TEG)技术回收船舶余热进行发电具有极其广阔的发展前景。因此提出了一种利用船舶柴油机尾气废热进行两级温差发电的新型装置。在对两级温差发电系统进行建模后,搭建了两级温差发电装置并进行了测试。理论分析和实验结果表明该装置利用温差发电技术对船舶余热回收是可行的。当热端温度达到473 K时,该温差发电实验装置可输出功率250 W,系统热效率为5.35％,相比单级TEG在相同条件下4.04％的热效率,该系统提高了32％。最后,对系统优化和装置的进一步改进进行了探讨。     

不同间隙比竖井内水流与平衡重二维流固耦合

目前,水力式升船机在国内外尚无投入实际运行,无实际设计、安装、运行经验可循。建立不同间隙比竖井与平衡重之间二维流固耦合数学模型,在非恒定流作用下,对不同间隙比时平衡重上升过程的水动力响应进行动态模拟。得出有利于该类升船机稳定运行的最优间隙比。     

水力式升船机平衡重波动机理

水力式升船机是一种新型的通航建筑物,它完全利用水的浮力来驱动承船厢运行,与传统形式升船机相比具有十分明显的优越性。设计并建立了水力式升船机单竖井概化物理模型,初步探讨影响水力式升船机运行稳定性的主要因素,对比不同试验工况下竖井水力学特性及平衡重波动等特性。结果显示:竖井与平衡重间隙比为0.061时,在一定范围内增大流量对平衡重上升过程波动几乎没有影响,且平衡重上升过程相对稳定。