微裂纹前缘应力强度因子的多元回归分析

根据文[1]计算的应力强度因子(SIFs)的近似值，利用逐步回归分析方法，对厚壁和薄壁的管道进行了考查，建立了应力强度因子与参数α、ξ、K1(a)中n的回归模型，得到了令人满意的结果，并将拟合和预测值与其他作者的结果作了比较。计算机结果表明，这种方法是可行的。     

分子筛供氧爆炸减压过程的数值模拟

 建立了爆炸减压时肺泡氧分压随时间变化的房室数学模型,对于分子筛供氧情况下爆炸减压过程进行了数值模拟,模拟结果和实测结果能够很好的符合.分析了飞行高度及供氧浓度对过程的影响.此模型为求解爆炸减压时肺泡氧分压降到临界值的时间提供了一种简单的方法,对高空飞行医务监督和应急供氧装备的设计有实际意义.     

脉冲微分系统关于部分变元的强稳定性

介绍了一种新的稳定性——脉冲微分系统的解关于部分变元的强稳定性,并进而讨论了该类稳定性问题. 首先建立了两个重要的引理,然后再借助于逐段连续的Lyapunov函数,得到了脉冲微分系统的零解关于部分变元强稳定性的一些判定定理.最后阐述了这些定理的应用.      

Flood susceptibility mapping by ensemble evidential belief function and binomial logistic regression model on river basin of eastern India

Flooding is the overflow of water from stream, river, lake and sea that occurs all over the world and has disastrous effects on human society and environment. Frequent severe flood event in eastern India cause of death and damages every year so, the development of flood susceptibility method is needed for identifying the flood vulnerability areas to reduce the damages. Techniques of Remote Sensing (RS) and Geographical Information System (GIS) can help to flood susceptibility modeling by the accrued and analyzing huge amount of data in short time. The main objectives of this study are to determine the effectiveness of Evidence Belief Function (EBF), binomial Logistic Regression (LR) and ensemble of EBF and LR (EBF-LR) model with RS and GIS techniques for flood susceptibility mapping and spatial prediction of flood-susceptible areas in the Koiya river basin of West Bengal, India. Eight flood conditioning factors; Land use and land cover (LULC), soil, rainfall, normalized differences vegetation index (NDVI), distance to river, elevation, topographic wetness index (TWI) and stream power index (SPI) have been used, and total 264 historical flooding points were mapped, and randomly divided in to training (70%) and validating (30%) dataset. Flood susceptibility map has been generated by applying EBF, LR and ensemble EBF-LR method with the help of training and eight causative factors dataset. The maps have been divided in to six classes; extremely low, very low, low, moderate, high and very high. The receiver operating characteristic (ROC) curve has been used to accuracy assessment of the susceptibility map, and the area under curve (AUC) disclosures 87.9%, 85.2% and 84.1% prediction rate for the EBF-LR, EBF and LR model, respectively. This study is helpful to flood management program, dissection makers and planning in local administrative level.     

面向多电飞机的脉冲波形下局部放电规律

为满足多电飞机（MEA）的大功率用电需求，系统工作电压需要进一步提高，而较高电压会增加相关部件的绝缘失效风险。面向多电飞机特定工作场景和参数，搭建了模拟飞机电作动器中的绕组间绝缘故障测试平台，开展了1 kHz范围内的局部放电（PD）大量重复实验，研究了特定电压幅值、正弦波和方波脉冲波形下局部放电幅值、放电重复率和放电相位等统计特征，并计算评估了不同频率值下多电飞机中的局部放电行为。实验结果表明：在设定频域范围内，方波脉冲下的起始放电电压（PDIV）都低于正弦，方波脉冲波形对绝缘影响更大；随着频率升高，放电幅值逐渐降低，但放电重复率几乎呈线性增长；放电时刻集中于上升沿/下降沿末端。以50 Hz作为对比基准频率，1 kHz时的放电幅值降低80%，而放电重复率增加11.92倍，较高频率下多次累积的小幅值击穿成为威胁绝缘失效的主要原因。计算分析认为高频下空间电荷场强变化导致的放电延迟时间减少和周期数目增加分别导致局部放电脉冲幅值降低和放电重复率增加。本实验结果有助于针对多电飞机电气系统和相关装备开展针对性绝缘测试和评估，并有望为多电飞机向大功率高电压方向的设计提供参考和借鉴。     

The effect of solar and geomagnetic parameters on total electron content over Ankara,Turkey

In this study, the relationship between total electron content (TEC) and solar and geomagnetic parameters for Ankara station (39.7 N, 32.76 E), Turkey located in the mid-latitude ionosphere is investigated. In this context, F10.7 solar flux and Interplanetary Magnetic Fields (IMF) from solar parameters and Kp and Dst indices from geomagnetic parameters affecting on TEC are considered. The relationship between the variables is investigated by means of the statistical multiple regression model at the universal time (UT) (Local Time = UT + 2 h) 1200 and 2400 in the years when the 24th solar cycle was minimum (2007–2009) and maximum (2015). As a result, it is found that explainable rates by solar and geomagnetic parameters of TEC changes in 2007–2009 are lower than in 2015 at daytime, while the explainable rates in the solar minimum years are higher than those the maximum year at nighttime. To be higher than the solar maximum of explainable rate in the solar minimum years at nighttime may be related to the fact that the dynamics of the ionosphere is significantly different than expected in this deep minimum period. As expected in 2015, the relationship between TEC and independent parameters is greater at daytime than at nighttime.     

基于支持向量回归代理模型的气动力优化设计

目前,气动力优化设计中通常基于经验风险最小化原则构建代理模型,预测精度的提高需要更多的训练样本,计算代价较大,同时盲目降低代理模型的训练误差难以避免过学习问题。针对上述问题,首先提出采用支持向量回归(SVR)方法基于结构风险最小化原则构建代理模型的思路,然后对测试函数和翼型阻力进行预测,最后对某型运输机机翼进行优化设计试验。结果表明:与其他代理模型对比,基于SVR的代理模型在小样本情况下具有较好的泛化能力,并且能够快速准确地预测气动特性,在飞机优化设计中,可以提高工作效率,优化结果可靠、可控。     

Multi-view space object recognition and pose estimation based on kernel regression

The application of high-performance imaging sensors in space-based space surveillance systems makes it possible to recognize space objects and estimate their poses using vision-based methods. In this paper, we proposed a kernel regression-based method for joint multi-view space object recognition and pose estimation. We built a new simulated satellite image dataset named BUAA-SID 1.5 to test our method using different image representations. We evaluated our method for recognition-only tasks, pose estimation-only tasks, and joint recognition and pose estimation tasks. Experimental results show that our method outperforms the state-of-the-arts in space object recognition, and can recognize space objects and estimate their poses effectively and robustly against noise and lighting conditions.     

基于管制员工作负荷的终端区容量评估

对现有的基于管制员工作负荷的空域容量评估方法进行分析,并比较各自的特点。提出了改进的基于管制员工作负荷的容量评估模型,模型的建立不仅考虑了管制员工作负荷的不同类别,即通信负荷、非通信负荷和思考负荷,还考虑了空域内航路结构的复杂性,即区分空域内不同航路走向上运行的航空器数量。描述了基于新建模型的容量评估方法。以哈尔滨机场终端区为背景,在雷达管制的基础上,使用新建立的模型,采用回归分析方法,计算了终端区容量,验证了所提模型和方法的可行性与适用性。     

含石蜡燃料初步研究

含石蜡燃料具高退移速率特性且成本低,是固液混合发动机理想能源。制取了在气氧矩形燃烧器中燃烧时不发生融化的含石蜡燃料。实验表明：将50％HTPB置换为石蜡,退移速率可提高1．37倍;在燃料中添加金属镁铝合金,可提高燃料密度和退移速率;添加碳黑可提高燃料密度,但退移速率略有下降。