CPL冷凝单管融化过程的双倒易边界元分析

1引言CPL（毛细泵两相流回路）能传输较高的热负荷，而且不需要循环泵、阀门等运动部件，重量轻可靠性好；在飞行器热控制方面有很好的应用前景[1]。CPL在恶劣的空间环境中运行，需要防止工作介质出现冷冻，为此，我们已经用解析[2]和数值的方法[3]进行了初步的分析，得到了一些可供工程设计参考应用的结果。另外，在恶劣的空间环境中，如果出现冻结，需要融化起动，热管的安全设计需要研究它的融化特性，以确保热管在空间能正常运行。双倒易边界元方法用Laplace基本解[4]，通过对一类偏微分方程两侧进行转化，将它全部转化为纯边界积分…     

Palaeogeothermal response and record of the effusing of Emeishan basalts in the Sichuan basin

Thermal history of the Sichuan basin is reconstructed based on vitrinite reflectance from boreholes in the basin using a paleo-heat flow method.The results show that the Sichuan basin experienced a relatively low heat flow period in the Early Paleozoic,and an elevated paleo-heat flow,ranging 60-80 mW/m2 with a maximum as high as 100 mW/m2 around 259 Ma,from the beginning of the Late Paleozoic to the end of the early Permian,and a decreased paleo-heat flow from the late Permian to the late Triassic,and then ...     

Calibration of a γ-Re_θ transition model and its application in low-speed flows

The prediction of laminar-turbulent transition in boundary layer is very important for obtaining accurate aerodynamic characteristics with computational fluid dynamic(CFD)tools,because laminar-turbulent transition is directly related to complex flow phenomena in boundary layer and separated flow in space.Unfortunately,the transition effect isn’t included in today’s major CFD tools because of non-local calculations in transition modeling.In this paper,Menter’sγ-Re_θtransition model is calibrated and incorporated into a Reynolds-Averaged Navier-Stokes(RANS)code-Trisonic Platform(TRIP)developed in China Aerodynamic Research and Development Center(CARDC).Based on the experimental data of flat plate from the literature,the empirical correlations involved in the transition model are modified and calibrated numerically.Numerical simulation for low-speed flow of Trapezoidal Wing(Trap Wing)is performed and compared with the corresponding experimental data.It is indicated that theγ-Re_θtransition model can accurately predict the location of separation-induced transition and natural transition in the flow region with moderate pressure gradient.The transition model effectively imporves the simulation accuracy of the boundary layer and aerodynamic characteristics.     

液相前驱体转化法制备ZrB_2粉末

采用液相前驱体转化法制备ZrB2粉末。首先以聚乙酰丙酮锆、硼酸、酚醛树脂为原料制备了ZrB2前驱体,通过在高温下发生碳热还原反应热解前驱体得到ZrB2粉末。采用傅里叶红外光谱仪(FT-IR)、差热-热重分析仪(TG-DTA)、X射线衍射仪(XRD)、电感耦合等离子光谱发生仪(ICP)和扫描电镜(SEM)对ZrB2前驱体及热解产物进行了表征和分析。结果表明,该ZrB2前驱体易溶于常用溶剂,加工性能优良,可在相对较低的温度(1600℃)下热解得到纯度较高的ZrB2粉末;ZrB2前驱体在pH值不大于4的反应环境下,反应时间越长制备的ZrB2陶瓷粉末纯度越高;ZrB2粉末颗粒尺寸为2～4μm,粉末中存在ZrC晶体、游离碳和少量氧杂质。     

由二苯二羟硅烷与钛酸四丁酯反应合成硅钛低聚物的研究

以二苯二羟硅烷Ph2Si(OH)2和钛酸四丁酯Ti(OBu)4为原料,利用本体聚合法合成了一种有机硅钛低聚物,并采用凝胶渗透色谱仪(GPC)、扫描电子能谱仪(EDS)、傅里叶红外光谱仪(FT-IR)、核磁共振仪(NMR)、质谱仪(MS)、X射线衍射仪(XRD)、热重分析仪(TGA)等对该低聚物进行了表征。结果表明,该低聚物由一系列分子量在517~1248之间的化合物构成,有些由Si—Ti键连接而成,也有些仅是二苯二羟基硅烷的低聚体。TGA研究表明,该低聚物在1000℃氮气氛中质量保持率为48.9%,具有较好的耐热性能。     

Scientometric analysis of physics (1979–2008): A quantitative description of scientific impact

Citations are a way to show how researchers build on existing research to further evolve research.The citation count is an indication of the influence of specific articles.The importance of citations means that it is valuable to analyze the articles that are cited the most.This research investigates highly-cited articles in physics (1979-2008) using citation data from the ISI Web of Science.In this study,1544205 articles were examined.The objective of the analysis was to identify and list the highly-product...