Generalized constructal optimization of strip laminar cooling process based on entransy theory

A strip laminar cooling process is investigated in this paper. Entransy theory and generalized constructal optimization are introduced into the optimization. Total water flow amount(WFA) in the laminar cooling zone(LCZ) and complex function are taken as the constraint and optimization objective, respectively. The entransy dissipation(ED) and maximum temperature different(MTD) of the strip are simultaneously considered in the complex function. WFA distributions of the headers in the LCZ are optimized. The effects of the total WFA, strip thickness and cooling water temperature on the optimal results are analyzed.The optimal cooling scheme is the eleventh cooling mode for the considered total 257 cooling schemes, and the complex function,ED and MTD of the strip are decreased by 11.59%, 5.59% and 17.58% compared with the initial cooling scheme, respectively.The total WFA and strip thickness have the obvious influences on the optimal cooing scheme, but the cooling water temperature has no influence in the parameter analysis range of this paper. The “generalized optimal construct” derived by minimum complex function shows a compromise between the energy retention and quality of the strip.     

乙烯装置原料多样性优化分析

武汉800 kt/a乙烯装置在开车成功后,结合中原地区原料来源多样,原料组成复杂的特点,通过对原料组成和裂解炉产品收率分析,得到原料种类优化方向,并对裂解炉工艺操作等方面进行细化,配合原料多样性的调整。     

基于MGE管理的地形图数据转换到ArcGIS平台的方法及实现

在对本院原有的MGE平台管理下的地形图数据进行分析和探讨后,借助MGE的升级平台GeoGraphics输出ArcGIS认可的shape格式,从而实现dgn数据到ArcGIS平台的转换.     

BEPCⅡ SSM磁体控制阀箱内氦冷却管线热应力分析

北京正负电子对撞机重大改造工程(BEPCⅡ)超导螺线管磁体(SSM)的控制阀箱是该磁体低温冷却系统的主要设备之一,用来分配、调节和控制超导磁体及其电流引线的冷却介质流量.低温下磁体超导导线及其冷却管会产生冷缩变形,变形量要在控制阀箱内给与补偿.同时阀箱内来流和回流氦冷却管线布置紧凑,需要判断是否要采取措施来补偿冷缩变形.本文运用有限元分析软件ANSYS对BEPCⅡ SSM控制阀箱内冷却管线的热应力进行模拟及分析,从而为该阀箱内冷却管线的设计及布局提供理论依据.     

管线数据建库过程中的质量控制

管线探测成果的质量直接关系到地下管网信息系统建设的成功与否,对进入空间数据库的管线数据的质量检查及控制,是系统建立过程中的一个重要环节。本文结合长沙市地下管网信息系统建设的实例,详细阐述了管线数据建库过程中的质量控制方法,提出了一套有效的质量控制检查手段,并研制出成果自动检查程序,确保了成果的完整性、可靠性和准确性,并大大减少了检查的工作量。     

竹集成材家具的技术问题及其对策

通过讨论竹集成材家具的生产工艺，分析了竹集成材家具生产中遭虫蛀、霉变和变形的主要原因及相应对策。     

Constructal entransy dissipation rate minimization of a rectangular body with nonuniform heat generation

Based on construtal theory, a nonuniform heat generation problem in a rectangular body is investigated in this paper. Entransy dissipation rate (EDR) is taken as the optimization objective. The optimal body shapes with constant and variable widths of the high conductivity channel (HCC) are derived. For the rectangular first order assembly (RFOA) with constant cross-section HCC, the shape of the RFOA and width ratio of the HCCs are optimized, and the double minimum EDR is obtained. The heat transfer performance of the RFOA becomes worse when the nonuniform coefficient increases. For the RFOA with variable cross-section HCC, the EDR of the RFOA can be minimized for four times. Compared the optimal construct based on minimum EDR of the RFOA with that based on minimum maximum temperature difference, the shape of the former optimal construct is tubbier, and the average temperature difference is lower. In the practical design of electronic devices, when the thermal safety is ensured, the constructal design scheme of the former optimal construct can be adopted to improve the global heat transfer performance of an electronic device.     

Entransy dissipation minimization for generalized heat exchange processes

This paper investigates the MED(Minimum Entransy Dissipation) optimization of heat transfer processes with the generalized heat transfer law q ∝(△(T~n))~m T. For the fixed amount of heat transfer, the optimal temperature paths for the MED are obtained. The results show that the strategy of the MED with generalized convective law q ∝(△T)~m T is that the temperature difference keeps constant, which is in accordance with the famous temperature-difference-field uniformity principle, while the strategy of the MED with linear phenomenological law q ∝△(T~(-1)) is that the temperature ratio keeps constant. For special cases with Dulong-Petit law q ∝(△T)~(1.25) and an imaginary complex law q ∝(△(T~4))~(1.25), numerical examples are provided and further compared with the strategies of the MEG(Minimum Entropy Generation), CHF(Constant Heat Flux) and CRT(Constant Reservoir Temperature) operations. Besides, influences of the change of the heat transfer amount on the optimization results with various heat resistance models are discussed in detail.     

An estimation model of time-varying origin -destination flows in expressway corridors based on unscented Kalman filter

On the basis of measurable time series of mainline and ramp flows from traffic counts and the assumption of travel time distributions, this research presents a dynamic system model and its on-line estimation algorithm for recursive estimation of time-varying origin-destination (OD) matrices in expressway corridors. The proposed model employs a macro-traffic flow model to estimate travel times of OD flows and uses parameters of the traffic model as state variables, which are added to the constrained function of the system. To improve the model efficiency, we revise the travel time distribution based on the feature of normal distribution. The research employs a newly developed filtering technique, called unscented Kalman filter. The proposed model is evaluated with simulation experiments. Numerical analyses with respect to the sensitivity of the selection of initial parameters on the estimation results indicate that the proposed model is sufficiently reasonable and stable for real-world applications. Supported by the National Natural Science Foundation (Grant No. 60674011)