X射线双星系统的探测

搜寻X射线双星并建立大规模样本是解决众多科学问题(如\"银河系中有多少黑洞X射线双星?黑洞和中子星之间有无质量间隙?球状星团中有无黑洞?\"等)的基础.爱因斯坦探针卫星拥有更灵敏的探测能力,将在运行的几年之中,预计可以发现一批新的中子星和黑洞X射线双星,研究其空间和动力学质量分布成为解决上述问题的关键.国家重点研发计划(编号:2016YFA040080X);;国家自然科学基金(编号:1133305);;中国科学院战略性先导科技专项(编号:XDA15052100,XDB23040000)资助项

Ownership, Competition and Industrial Performance:An Empirical Analysis Based on the Data of Chinese Machinery Industry

本文利用中国机械产业四位数代码行业的数据,实证地比较了产权、市场竞争对产业绩效的相对重要性。研究结果显示,在转轨经济中,至少就中国机械行业而言,产权与竞争都是影响产业绩效的重要因素,其中产权似乎更为重要。Using the data of four-digit of China Machinery Industry,the author empirically compare the effect of competi-tion and ownership on the industry performance. The founding shows that in transition economy at least for China, ownership and competition are both the important factors affecting industry performance, and that ownership seems more important

ASSESSMENT ON COMPETENCY MODEL OF SENIOR MANAGERS

该文采用BEI行为事件访谈技术探讨了我国通信业高层管理者的胜任特征模型 ,研究结果表明 :(1)优秀组与普通组在访谈字数的长度上无明显差异 ,而胜任特征编码的频次与访谈长度上有显著性相关 ,编码指标采用平均分数具有更好的稳定性 ; (2)采用概化理论计算不同编码者的编码一致性 ,结果表明 ,胜任特征评价法具有较好的编码者一致性 ; (3)效标群体的分析结果证实 ,我国通信业高层管理者的胜任特征模型包括 :影响力、组织承诺、信息寻求、成就欲、团队领导、人际洞察力、主动性、客户服务意识、自信和发展他人</p

企业高层管理者胜任特征模型评价的研究

该文采用BEI行为事件访谈技术探讨了我国通信业高层管理者的胜任特征模型，研究结果表明：（1）优秀组与普通组在访谈字数的长度上无明显差异，而胜任特征编码的频次与访谈长度上有显著性相关。编码指标采用平均分数具有更好的稳定性；（2）采用概化理论计算不同编码者的编码一致性，结果表明，胜任特征评价法具有较好的编码者一致性；（3）效标群体的分析结果证实，我国通信业高层管理者的胜任特征模型包括：影响力、组织承诺、信息寻求、成就欲、团队领导、人际洞察力，主动性，客户服务意识、自信和发展他人

北方生态脆弱区农户兼业对耕地利用的影响(英文)

当前我国农户兼业现象十分普遍。本文基于在内蒙古太仆寺旗的农户调查数据,采用单因素方差分析法,对生态脆弱区农户兼业及其对耕地利用的影响进行了研究。结果表明:当前研究区农业劳动力非农就业和农户兼业现象十分突出,而兼业程度不同的农户,其经营土地的方式差异明显。非农就业户通过将其土地转给其他农户而脱离了农业耕作,这同时满足了其他农户扩大土地经营面积的愿望。种植结构差异不大,均体现为劳动生产率高的作物具有优势;对于有耕地利用行为的纯农业户、I兼型农户和II兼型农户,随着兼业程度的增加,物质投入增加,说明农户兼业使其资金约束减小,增加了资金投入能力,但是在劳动力约束下,兼业农户的劳动力投入减少,且务农劳动力妇女化、老龄化和文化低等现象突出;作物单产和土地净收益纯农业户大于兼业农户,说明劳动投入对土地产出更为重要。文章最后认为建立农业劳动力非农就业与耕地利用相互协调的机制,是解决生态脆弱区生态安全与农业生产之间矛盾的重要途径

Evolution of heat transfer at the stagnation point during the detached bow shock establishment

The diffraction of a shock wave over a stationary body is a problem of interest associated with the starting of shock tubes and expansion tubes which are well suited to studies of hypersonic flows. However, these facilities are characterized by very short test times. The transient parameters during the establishment of the detached bow shock in such impulsive facilities are important for both data processing and experimental design. In the present study, numerical simulations are conducted to investigate the diffraction of a normal shock wave over a sphere and the subsequent transient phenomena in a viscous perfect-gas flow field. The incident shock Mach number ranges from 3 to 5 with a specific heat ratio of 1.4. Based on the theoretical description of the reflected shock position during bow shock formation, approximate solutions for the time histories of the stagnation-point heat flux are also derived. The analytical and numerical results agree well. The results show that the stagnation-point pressure and heat flux approach their steady-state values much more rapidly than the shock detachment distance does

Investigation of dual ignition for a detonation-driven shock tunnel in forward driving mode

A detonation-driven shock tunnel is useful as a ground test facility for hypersonic flow research. The forward detonation driving mode is usually used to achieve high-enthalpy flows due to its strong driving capability. Unfortunately, the strong detonation wave front results in diaphragm fragments that disturb the test flow and scratch the nozzle or test models. In this study, a dual ignition system was developed to burst a metal diaphragm without fragmentation in the forward driving mode. A series of experiments were conducted to validate the proposed technique. The influences of the delay time setting on the test conditions were investigated in detail. Numerical simulations were also conducted to obtain a better understanding of the wave processes in the shock tube. The results showed that the dual ignition system solved the diaphragm issues in the forward driving mode. The test time was shortened due to the additional ignition close to the primary diaphragm; the smaller the delay time, the shorter the effective test time. However, a small amount of time loss is considered worthwhile because the severe diaphragm problems have been solved. (C) 2020 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd

传感器安装对平板气动热测量精度的影响

对高超声速飞行器来说,气动热的准确预测是其合理选择防热材料及热结构设计的重要依据,但目前在激波风洞试验中气动热的高精度测量仍较为困难,热流的测量精度受到诸多非理想因素的影响,但传感器安装对热流测量精度的影响却鲜见研究。选取平板模型来研究传感器非理想安装对气动热测量精度的影响,针对不同的传感器安装偏差(凸出或凹入模型表面0.1～0.5 mm),分析不同雷诺数下传感器安装对气动热测量精度的影响规律及机理。研究结果表明:传感器安装对气动热测量精度有较大影响,凸出安装会导致热流测量结果偏大,而凹入安装则会导致测量结果偏小,热流偏差会随着安装偏差的增大而增大,且高来流雷诺数下传感器非理想安装所引起的热流误差更大;以边界层当地厚度对凹凸程度无量纲化,非理想安装带来的测量偏差只与该无量纲参数相关。研究结果能够为气动热测量的实验方案设计及测量误差分析提供一定的理论指导