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排序方式: 共有357条查询结果,搜索用时 11 毫秒
1.
基于MVC模式的Struts框架研究 总被引:5,自引:0,他引:5
Struts框架是当前Web应用开发中最流行的开发框架之一。在介绍了MVC模式的基础上对Struts框架的体系结构和工作流程作了介绍,并结合数据库连接池实现了一个电子商务网站的客户登录系统。 相似文献
2.
The main purpose of this paper is to investigate numerically the effects of solidification on the heat transfer characteristics of the liquid metal layer, for use in accident analyses. The situation is very similar to an overlying liquid melt pool that could be fooned in the reactor lower head during the late phase of a severe nuclear accident. Based on a computational model, MPCOOL, the numerical predictions were then assessed through a comparison with the experimental data that was obtained with various boundary temperature conditions and geometrical aspect ratios, especially for the Ra-Nu relationship. For the cases with solidification, the results of the comparison show that(a) the computational model does show a good agreement with heat transter rates inferred from the experimental data, with a few exceptions at the Ra numbers which suggest a turbulent transport; and also (b) the computational model underpredicts the heat transfer rates by about 6% than that inferred from the experimental data when it is integrally evaluated with the Ra-Nu correlation. The foregoing results are mainly due to the currently limited applicability of the computational model up to the laminar-to-turbulence transition flows and its application to the turbulence flows because it is always subjected to a model uncertainty between the laminar and turbulence. Next, an additional comparison for the cases with and without solidification was made to examine the effects of the solidification on the energy partition within the liquid metal layer and its effects on the directional heat transfer rates. The results of the comparison show that the computational model for the case without solidification predicts higher heat transfer rates by about 15% than when solidification is included, but there isn't any experimental data that directly supports this trend. 相似文献
3.
为保证49-2游泳池式反应堆在超寿期下的安全运行,需进行超设计基准事故分析。由于难以采用概率安全评价(PSA)方法进行分析,所以本文无条件假设最严重事故来得到一保守结果。主要分析了全厂断电下未能紧急停堆的预期瞬变(ATWS)、水平孔道断裂和停堆后堆芯完全裸露的事故,以及应急能力。结果表明:在全厂断电ATWS下堆芯是安全的;水平孔道断裂及其他因素造成失水时,只要2.5h内堆芯不裸露即可保证燃料元件不熔化;非能动破坏虹吸能力和多样的应急补水方式能保证堆芯不裸露。 相似文献
4.
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两种池沸腾强化换热管的传热性能实验研究 总被引:1,自引:0,他引:1
对两种用于池沸腾换热的强化管在蒸发温度为5℃的工况下进行了水平管外传热性能的实验研究.两种管子为管内外双侧强化管,管外表面同属于TURBO-B类的强化换热管,但表面形状有区别.利用威尔逊图解法确定这两种管型的管内外换热系数的关联式,同时,根据实验测得的数据对这两种管型的换热性能进行比较.结合金相显微镜拍摄的外观形状,分析尺寸结构对强化换热管的换热性能的影响.结果得出:在相同工况下,准三角形形状的管内螺纹换热性能要比梯形好,且管内螺纹数越多,换热性能越好;在一定热流密度范围内,管外换热系数随着热流密度的增加而变大,这主要与管子外表面结构的凹穴半径、凹穴开口尺寸、次级表面通道的宽度和形状等因素有关,且翅顶表面刻画的浅槽有利于池沸腾换热. 相似文献
6.
随着建筑业向智能化、信息化的转型发展,BIM逐渐成为行业中的重要工具和方法。通过BIM技术进行三维设计,可作为发展装配式建筑信息化的一种方式,现阶段单一的Revit软件还无法满足装配式建筑的所有设计功能。但Revit作为BIM领域最常用的软件之一,拥有丰富的开发接口,可导出多种文件格式,可以通过二次开发实现一个模型运用到整个项目的效果。本文采用C#语言通过Visual Studio平台对Revit进行二次开发,创建装配式预制构件库及参数化建模插件,实现柱、梁、板、剪力墙、楼梯等预制构件的快速绘制和标准化建模。同时在模型建立的基础上,通过插件实现参数化建模,重复性工作被自动化技术所取代,提高了建模的效率。 相似文献
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8.
Small-scale pool fire tests of ethanol-water mixtures are described in this paper. The main goal of the tests was to obtain data on the heat release rate per unit area, the total heat release per unit area, and the effective heat of combustion of such mixtures with ethanol percentage of 20 vol% or more. The results can be utilised in the interpolation and extrapolation of these quantities for different ethanol percentages and irradiance levels. In addition, the results give information on the heat release of possible pool fires of alcoholic beverages in a retail store in the case of a fully developed fire. It was concluded that significant fire load is not formed until the ethanol percentage of the alcoholic beverage is ca. 20 vol% or more. The data reported can also be used as an input to simulations of ethanol-water mixture pool fires in the performance-based fire safety design. 相似文献
9.
The radiative characteristics of laboratory-scale pool fire flames have been studied in detail. Experiments were conducted in the ASTM E2058/ISO 12136 Fire Propagation Apparatus (FPA). Eleven liquid fuels with different sooting propensities, including alcohols and alkanes, burning in a 9.5 cm diameter quartz dish were considered. Radiative power distribution (along the flame axis) and global radiant emission were measured for all the fuels by using slit and wide-view-angle radiometers, respectively. The effects of measurement location and fuel type on the measured data were investigated. Radiation distribution profiles for a given fuel, when adequately normalized, show little sensitivity to the horizontal separation distance of the slit radiometer. Fuels with similar chemical structures exhibit similar distributions, consistent with flame image analyses. The radiative power distributions along with the wide-view-angle radiometer data were used to derive radiant fractions for the pool fires studied by applying a multiple-point source (MPS) radiation model. To examine the sensitivity of the calculated radiant fractions to the measurement location, the position of the wide-view-angle radiometer was considerably varied both vertically and horizontally. The results show that the radiant fractions derived based on the measured radiative power distribution are independent of the location of the wide-view-angle radiometer and consistent with literature values. Therefore, the approach developed in this study presents a flexible methodology apt for the accurate determination of radiation properties of diffusion flames in a laboratory setting. 相似文献
10.