中国无人机安全监管

 随着无人机产业的蓬勃发展，加快推进相关立法，加强行业安全监管，已变得十分必要和迫切。综合研究了中国现有无人机相关的监管法规制度情况，分析了各项管理措施和政策，剖析了监管存在的问题，并借鉴国外主流做法和经验，提出中国无人机安全监管应围绕“人、机、环”关键环节，从国家层面建立统一管控平台，加快相关法规标准制定，规范反制设备使用，通过安全检测、试点宣传等手段，推动建立健全安全监管体系。     

不同波长处的相对光谱功率对光源颜色的影响

从色度学理论出发,在1976（L*a*b*）颜色空间内,探讨了不同波长处的相对光谱功率分布变化对光源颜色的影响情况,建立了数学表达式,从而能准确地判断各个波长点对光源颜色的影响。并且以A光源和D65光源为例,判断了A光源和D65光源各个波长处的单位光谱功率的改变对颜色的影响。运用这个数学表达式,在模拟标准光源的过程,就可以对某些波长点实行重点匹配,以便更准确的对标准光源进行模拟。在标准光源的模拟过程中,发现不同波长处的相对光谱功率分布变化对光源的颜色有不同的影响。     

LAN 系统的故障容错及其排除方法

对ＬＡＮ网使用过程的常见故障以及操作系统容错技术进行了分析和总结,并提出了避免和解决问题的方法。     

既有朝阳嘉陵江大桥接触网悬挂安装研究

既有非电化铁路电气化扩能改造是当下中国铁路建设的重要方向。既有铁路桥上接触网悬挂安装设计是既有铁路电气化改造的重要一环,本文针对重庆枢纽既有朝阳嘉陵江大桥开展了接触网特殊悬挂安装研究,为国家重点建设项目节省了投资,缩短了建设工期。     

自制孔内摄像系统在钻孔施工中的应用

孔内摄像系统可以直接实时观察钻孔内部影像,能达到地质、测井、钻探无法做到的效果,在地质分析、钻探事故处理中起着非常重要的作用。本文从孔内摄像系统工作原理、工作流程、所用材料,制作过程、操作方法以及在实际施工中的应用加以叙述。     

风电场向孤岛输电的VSC-HVDC Light的建模与仿真

介绍了以VSC控制为基础的HVDC Light的系统结构和工作原理,在MATLAB中创建了风电场向孤岛输电的VSC-HVDC Light系统仿真模型,并对其进行了稳态仿真研究.对仿真结果进行分析可知,系统直流电压基本稳定在给定的电压值,两端直流电压实现了协调配合,有功功率实现了协调控制和自动平衡传输,各状态量都符合理论值,模型准确模拟出了VSC-HVDC Light系统的稳态工作状况,为实际工程提供了科学的理论依据.     

The leading correlation of the winter Aleutian Low with surface air temperature during the subsequent summer over the Arctic and its possible mechanism

The variations of surface air temperature(SAT)over the Arctic are closely related to global climate change.Based on reanalysis datasets and a newly defined Aleutian Low intensity index,we found a good correlation between intensity of winter Aleutian Low and the SAT over the Arctic during the subsequent summer.Explanations were given using correlation analysis,composite analysis,and singular value decomposition methods.When intensity of winter Aleutian Low was weaker,sea surface temperature appeared higher in the North Pacific in the subsequent spring and summer,resulting in mean meridional circulation anomalies and 500 hPa geopotential height anomalies in spring and summer.Anomalous upward motion in mid-latitudes and downward motion in high latitudes(Ferrel cell weakening)transported the warmer air to the north from lower layer to the upper layer followed by increases in the SAT over the Arctic.Anomalous downward motion over about 75°N also caused consequent adiabatic warming and contributed to inhibit the heat transportation from surface to upper layer.Negative 500 hPa geopotential height anomalies existed in mid-latitudes and positive anomalies existed in high latitudes.The pattern(low-in-south and high-in-north)benefited from increasing the inflow volume flux of the Bering Strait,which also made the SAT over the Arctic increase.The results of this study reveal the process that the summer SAT over the Arctic was modulated by interannual variability of intensity of winter Aleutian Low.     

Microstructure and oxidation resistance of SiC–MoSi2 multi-phase coating for SiC coated C/C composites

In order to improve the anti-oxidation of C/C composites, a SiC–MoSi2multi-phase coating for SiC coated carbon/carbon composites(C/C)was prepared by low pressure chemical vapor deposition(LPCVD) using methyltrichlorosilane(MTS) as precursor, combined with slurry painting from MoSi2 powder. The phase composition and morphology were analyzed by scanning electron microscope(SEM) and X-ray diffraction(XRD) methods, and the deposition mechanism was discussed. The isothermal oxidation and thermal shock resistance were investigated in a furnace containing air environment at 1500 1C. The results show that the as-prepared SiC–MoSi2coating consists of MoSi2 particles as a dispersing phase and CVD–SiC as a continuous phase. The weight loss of the coated samples is 1.51% after oxidation at 1500 1C for 90 h, and 4.79% after 30 thermal cycles between 1500 1C and room temperature. The penetrable cracks and cavities in the coating served as the diffusion channel of oxygen, resulted in the oxidation of C/C composites, and led to the weight loss in oxidation.     

基于HLLC近似Riemann解的自由面流动数值模拟

对于自由面流动问题,发展了一种新的数值模拟方法.在该方法中,自由面的捕捉通过求解Level Set方程实现.该方程与流体力学控制方程耦合形成双曲系统方程,并采用人工压缩方法进行求解.为了提高计算的分辨率,发展了一种有限体积框架下的高阶WENO格式,并构造了基于HLLC近似Riemann算子的通量函数.对若干典型自由面流动问题进行了数值模拟,计算结果表明了该方法的有效性.     

改进的低复杂度BP译码算法

基于对数似然比的BP译码算法与标准BP译码算法相比,降低了一定的运算量,但仍具有较高的计算复杂度,硬件实现时需要消耗较高的资源。针对此问题,提出了一种变量节点动态更新选择的对数似然比BP译码算法,根据每一次迭代后变量节点外信息的收敛情况及校验方程的满足情况,动态地选择置信度最低的部分节点参与更新,其他置信度较高的节点则不进行更新。仿真结果显示,该算法译码性能与对数似然比BP译码算法相比,在0.5码率,10-4误码率时,1 024码长有0.1dB的性能损失,2 048码长性能损失仅有0.07dB,但从第4次迭代开始归一化运算量至少降低了50%。