空间飞行器追踪区设计

重点介绍了空间飞行器通过一次变轨机动与目标交会的可行机动方案，在对飞行时间普适公式分析的基础上，建立了一般性的轨道转移预测模型， 给出了一种寻求空间飞行器可行变轨点集的方法，并提出了追踪区的概念。通过仿真计算，分别对各种时间和燃料资源限制条件下的追踪区大小变化进行了分析，结果表明，利用该方法求出的变轨点能够满足空间交会对燃料和时间等各方面的要求，且方法简捷，易于实现。     

失速改出伞阻力特征面积估算方法

研究了高平尾布局飞机的气动特性。使用失速改出伞是飞机改出深失速的重要途径,但如何确定失速改出伞的关键参数(阻力面积等)却没有现成的方法。以ARJ21-700飞机为例,分别使用公式分析法、类比法综合估算出失速改出伞的关键参数,通过模型自由飞和模拟仿真分析验证其具有足够效能将飞机改出深失速状态。形成了一套新机失速改出伞的设计方法和关键数据图表,可供其他型号飞机失速改出伞的设计研制使用。     

Modeling urban heat islands in heterogeneous land surface and its correlation with impervious surface area by using night-time ASTER satellite data in highly urbanizing city,Delhi-India

The present study is an assessment and identification of urban heat island (UHI) in the environment of one of the fastest urbanizing city of India, Delhi Metropolis, employing satellite image of ASTER and Landsat 7 ETM+ in the thermal infrared region 3–14 μm. Temporal (2001 and 2005) ASTER datasets were used to analyze the spatial structure of the thermal urban environment subsequently urban heat island (UHI) in relation to the urban surface characteristics and land use/land cover (LULC). The study involves derivation of parameters governing the surface heat fluxes, constructing statistics of ASTER thermal infrared images along with validation through intensive in situ measurements. The average images reveal spatial and temporal variations of land surface temperature (LST) of night-time and distinct microclimatic patterns. Central Business District (CBD) of Delhi, (Connaught Place, a high density built up area), and commercial/industrial areas display heat islands condition with a temperature greater than 4 °C compared to the suburbs. The small increase in surface temperature at city level is mainly attributed to cumulative impact of human activities, changes in LULC pattern and vegetation density. In this study the methodology takes into account spatially-relative surface temperatures and impervious surface fraction value to measure surface UHI intensity between the urban land cover and rural surroundings. Both the spatial and temporal variation in surface temperature associated with impervious surface area (ISA) has been evaluated to assess the effect of urbanization on the local climate.     

Urban growth assessment around Winam Gulf of Kenya based on satellite imagery

Urban growth and population dynamics are among the most critical information needed for future economic development planning, natural resources allocation and environmental management. In the present work, two methods, the first based on night-time images produced by NOAA and population maps provided by Oak Ridge National Laboratory's (ORNL) LandScan, and the second one on SAR imagery, were used in order to assess the expansion of urban areas surrounding the Winam Gulf (Lake Victoria, Kenya) at different scales. In the time covered by night-time lights imagery, the study highlighted a period of constant growth rate between 2002 and 2006 and a negative trend after 2006 and 2008. This decrease may be related to two main events occurring in the study area between 2006 and 2007: the decline of the Lake Victoria level and the abnormal proliferation of the floating weeds within the Winam Gulf. Meanwhile, the urban feature extraction obtained at a different scale within a particular district from 1997 up to 2008 results in a constant growth rate. Population movements around this zone explain different dynamics that should be studied in detail in order to understand their particular roots.     

大型居住社区多元化管理模式研究——以上海市浦东新区为例

大型居住社区是郊区快速城市化的产物,其社区管理面临弱势群体集中、社区居民就业困难、社区自治程度低等困难.以上海市浦东新区为例,探讨一种多元化的社区管理模式,正确定位多元管理主体的关系,以实现社区复合治理为目标,促进社区自治.     

小积液情况下卧式转子的稳定性实验研究

盘腔积液现象在舰用燃气轮机工作过程中时有发生，汽化的滑油和水蒸气凝结形成积液。转子带动腔内的积液旋转，引发振动失稳，严重时会对发动机结构造成致命性破坏。为此，本文开展燃气轮机压气机盘腔积液的模拟实验研究，以双盘双支承的卧式柔性转子系统作为研究对象，重点关注小积液量的特点，对积液转子的动力学稳定性进行了研究。观测到转子的失稳现象，开展了不同积液体积、不同积液类型（水、植物油和滑油）等因素的影响规律研究，揭示了小积液的卧式转子动力学特征。研究结果表明：①对于积液失稳振动，存在失稳边界积液量，当积液量大于该边界值时，失稳将会发生。②失稳边界转速及恢复转速均高于临界转速。当转速高于失稳边界转速时，失稳将会发生。转速进一步增加，高于恢复转速时，失稳现象可能消失。③失稳时的振动特征为：出现幅值突增，次谐波成分也随之增加；基频和次谐波发生调制，表现出拍振特征。④随着积液体积的增加，失稳边界转速先减小后增加。⑤随着积液粘度系数增大，失稳边界转速和边界积液量均增大。     

氨合成-水热改性法制备氢氧化镁阻燃剂

为了解决氢氧化镁和聚合物之间的不相容问题, 对氨合成法-水热改性处理2步法制备高分散氢氧化镁阻燃剂进行了研究,分析了常温合成温度、水热改性温度和水热改性时间对制备大晶型、低比表面积氢氧化镁阻燃剂的影响.结果表明,经过水热改性处理改变了氢氧化镁晶体的生长习性,生成了形貌规则、粒径分布均匀、分散性良好的氢氧化镁六方片状颗粒.另外通过提高氯化镁浓度和氨水过量1倍,探讨了常温合成反应的转化率,认为应该在反应原料等当量下寻求提高转化率的可行方法.     

区域管制中Y2K问题的风险管理

Y2K将有可能造成管制区域中通信、导航、监视设备的全部或部分失效，为了保证飞行安全，必须进行风险管理。通过对假想空域中Y2K问题带来风险的分析，提出了几点控制风险的措施     

CX600车铣加工中心的回换刀点过程控制

本文介绍了在CX600车铣加工中心的制造过程中,利用用户程序和Part程序相配合，实现主轴刀具回换刀点过程的控制方案，该方案实际可行，并已用于生产实践。     

末端区域4D导引的水平轨迹计算方法

末端区域４Ｄ导引首先生成轨迹，然后生成沿该轨迹飞行的高度剖面，合理的速度剖面，最后生成自动引导飞机在规定时间着陆的４Ｄ导引指令。现简要讨论末端区域４Ｄ导引理论，主要推导了生成末端区域４Ｄ导引的首要算法－－水平飞行轨迹的计算方法。数值仿真结果表明，该方法只输入少量的航路点坐标数据和限制参数，就能计算出沿直线和曲线飞行的水平轨迹。