双排叉排孔气膜冷却特性研究 (二) 绝热有效温比

本文介绍双排叉排孔气膜冷却绝热有效温比η的测量结果和数值计算。根据η沿主流和横向的变化, 特别是在近孔区的分布规律分析了前后排孔二次射流的不同流动特点。数值计算采用求解椭圆方程的三维差分程序, 吹风比M等于0.6。      

低信噪比情况下识别模态参数的时域平均方法

 <正> 1.引官 模态参数识别方法在应用中需要解决的一个重要问题是观测噪声的干扰问题。为了有效地抑制观测噪声的影响,各种时域参数识别方法普遍引入了估计方法,以ITDM为代表的利用脉冲响应包括对脉冲激励的响应和脉冲响应函数)识别模态参数的识别方法还引入了噪声模态     

非系统RS码的删／错译码算法

研究了非系统RS码的删/错译码算法。详细阐明了删/错译码原理,推导了各步的计算公式。该算法特别适用于干扰严重的组合信道中级连RS码的译码。     

Review of shock wave detection method in CFD post-processing

In the present computational fluid dynamics (CFD) community, post-processing is regarded as a procedure to view parameter distribution, detect characteristic structure and reveal physical mechanism of fluid flow based on computational or experimental results. Field plots by contours, iso-surfaces, streamlines, vectors and others are traditional post-processing techniques. While the shock wave, as one important and critical flow structure in many aerodynamic problems, can hardly be detected or distinguished in a direct way using these traditional methods, due to possible confusions with other similar discontinuous flow structures like slip line, contact discontinuity, etc. Therefore, method for automatic detection of shock wave in post-processing is of great importance for both academic research and engineering applications. In this paper, the current status of methodologies developed for shock wave detection and implementations in post-processing platform are reviewed, as well as discussions on advantages and limitations of the existing methods and proposals for further studies of shock wave detection method. We also develop an advanced post-processing software, with improved shock detection.     

基于图像分析的雷达假目标逼真度计算

在对目标雷达图像进行分析的基础上,提取其图像特征,并通过一定的变换使其转化为假目标的逼真度指标,从而对雷达假目标的设计提供参考.     

Analysis of the brightness temperature features of the lunar surface using 37 GHz channel data from the Chang'E-2 microwave radiometer

Compared with other remote observations, brightness temperatures (T_B) derived from microwave emission measurements provide a unique means to characterize the physical properties of the lunar surface. Using Chang’E-2 microwave radiometer data, we produced 12 global T_B images of the lunar surface during a diurnal cycle with different local times separated by approximately 2?h. There are two types of remarkable T_B units on the lunar surface, the “hot regions” occurring during the lunar day in the lunar Maria regions and the “microwave cold spots” occurring during the nighttime typically related to young craters. Compared with their surroundings, the hot regions are much warmer during the lunar day and slightly colder at night, while the microwave cold spots are much colder during the lunar night and slightly warmer in the daytime. Moreover, the T_B heating and cooling rates of these two units are larger than others at the same average latitude where they are located during the lunar day, especially after sunrise and before sunset. The hot regions have a good agreement with the mare regions with high TiO₂ abundance. Besides, brightness temperatures in the lunar Maria correlate closely with their TiO₂ abundance. For most microwave cold spots, they agree with the young craters, and their brightness temperature distributions have a significant negative correlation with the lunar surface nighttime temperature and rock abundance.     

Inter-satellite calibration of FengYun 3 medium energy electron fluxes with POES electron measurements

We perform an L-shell dependent inter-satellite calibration of FengYun 3 medium energy electron measurements with POES measurements based on rough orbital conjunctions within 5?min?×?0.1?L?×?0.5 MLT. By comparing electron flux data between the U.S. Polar Orbiting Environmental Satellites (POES) and Chinese sun-synchronous satellites including FY-3B and FY-3C for a whole year of 2014, we attempt to remove less reliable data and evaluate systematic uncertainties associated with the FY-3B and FY-3C datasets, expecting to quantify the inter-satellite calibration factors for the 150–350?keV energy channel at L?=?2–7. Compared to the POES data, the FY-3B and FY-3C data generally exhibit a similar trend of electron flux variations but more or less underestimate them within a factor of 5 for the medium electron energy 150–350?keV channel. Good consistency in the flux conjunctions after the inter-calibration procedures gives us certain confidence to generalize our method to calibrate electron flux measurements from various satellite instruments.     

建构主义理论背景下廊坊市大学生信息素养教育改革路径

文章阐述廊坊市大学生信息素养教育存在的问题,并针对当前存在的教学问题提出建构主义理论背景下大学生信息素养教育改革的具体路径:一是树立以学生为中心,教师为主导的信息素养教学理念;二是应用建构主义学习理论鼓励和引导大学生挖掘和评估信息的能力;三是建设以"师生信息素养能力提升"为前提的队伍建设机制;四是强化个体的自我培育,注重信息道德素养的自主提升。     

Analysis of direct operating cost of wide-body passenger aircraft: A parametric study based on Hong Kong

Analysis of the Direct Operating Cost(DOC) of aircraft is an important step towards achieving financially sustainable aviation operations. However, the value of the DOC for different aircraft types and flight scenarios is not widely available. In this study, we perform a systematic analysis of the DOC of every wide-body passenger aircraft currently in production, using the method of the Association of European Airlines(AEA). The elements of the DOC, e.g. financial costs, maintenance costs, and flight costs, are evaluated individually. Several realistic flight scenarios are considered, each with differences in route distance, fuel price, passenger number, and seating arrangement. For each flight scenario, the most cost-efficient aircraft type is identified and evaluated in the context of operations from Hong Kong International Airport. The information provided in this study could be useful to airline operators and policy makers.