微型多轴旋翼无人机在山西省燃气输配管网安全管理提升中的应用

山西省内输气管网贯通全省南北，横跨东西，分布地区广，经过高后果区、采动采空区以及高陡边坡湿陷性黄土等不同的地形复杂区域，制约了常规人工巡护、风险识别、隐患预警等工作的进行，微型多轴旋翼无人机具有体积小、操作简单、机动性强、造价低、飞控智能化程度高的特点，具有搭载多种工作平台实时拍摄动态视频、高清晰照片及后台智能对比等功能。结合山西省输气管网管理工作的特点，分析了无人机在辅助管道巡护、高后果区风险识别、应急抢险中指挥和决策的应用，提高全省燃气管网的安全管理水平。     

Reaction Characteristic for Various Scale Explosive under Mild Impact

This work presents a varying trend of impact ignition threshold denoted by minimum impact velocity to trigger an ignition when the scale of the explosive changes. The effects of explosive scale factors on impact-induced reaction degree were investigated using Steven tests and numerical simulation for polymer-bonded explosive-C03 (a cyclotetramethylene tetranitramine [HMX]-based explosive) impacted by projectiles of various velocities. Two scale factors—that is, axial thickness and radius—were studied through various scale samples including Φ98 mm × 13 mm, Φ98 mm × 39 mm, Φ140 mm × 13 mm, and Φ140 mm × 39 mm. The velocities of projectiles and the impact and ignition processes were analyzed using a high-speed camera. The pressure histories were measured by embedded manganin pressure gauges and poly vinylidene fluoride stress gauges. The reaction overpressures of the explosive were obtained by blast pressure gauges to evaluate the reaction degree. The effects of explosive scale factor on reaction degree and characteristics under mild impact were summarized. In a certain range (larger than the diameter of the impact projectile), different sample diameters do not influence the velocity threshold, but the thickness of the samples does; that is, the velocity threshold increases with the thickness of the sample. The study also indicates that the ignition and explosion in Steven tests are mainly triggered by the overlapping of direct impact and reflected stress waves. Our numerical simulations results of pressure and ignition times are consistent with the experimental data. The obtained knowledge can be used to evaluate the safety of different scale HMX-based explosives under accidental impact or falls.     

基于“三带”理论的沉陷区边坡失稳过程分析

地下开采扰动给沉陷区内边坡稳定性带来不利影响。以抚顺老虎台矿开采沉陷区内某边坡失稳破坏为例，分析沉陷区内边坡失稳的动态演化过程。根据开采沉陷学“三带”理论，将处于开采沉陷区的东露天边坡岩土体划分为冒落带、裂隙带、弯曲下沉带和原生带4个特征区域,并分别计算出边坡处于3种“临界状态”时对应的地下开采深度。     

Scheme design considering network topology and multi-attribute decision-making for under frequency load shedding

Power system emergency control is one key defense strategy in contingencies for protecting the system from cascading blackout. Under Frequency Load Shedding (UFLS) is one such strategy to ensure system stability by shedding load to retrieve balance between power supply and demand. Novel UFLS scheme design and a scheme optimization approach are proposed in this paper to find the optimal load-shedding schemes for different network partition resulted from contingencies. To obtain all possible UFLS schemes for a certain area, a candidate scheme set design algorithm based on value assigning of scheme parameters is proposed and then a relatively complete candidate scheme set is constructed. Considering network splitting caused by protection, several subsystems may exist from the reconstruction of independent network areas. The concept of homological area is defined and a graph-based method is used to analyse system topology change. Then, a multi-attribute decision-making (MADM) algorithm is introduced for order preference by similarity to an ideal solution (TOPSIS) for global optimizing candidate schemes. Optimal schemes for an area in both isolated area and homological area cases can be derived from all feasible UFLS schemes by MADM method. Simulation results demonstrate that the UFLS schemes can effectively restore system frequency in different network topologies.     

非饱和土大气张力通用公式与库仑土压力

推出大气张力库仑土压力的近似计算方法：假设临界破裂角为已知,可以考虑多层粘性土、坡面任意荷载、水和气压力。提出粘性土的结合水膜可靠连接面积率修正系数等于粘粒含量。推出大气张力库仑抗剪强度公式的Cm 形式,Cm 是膜的抗剪强度贡献。     

Oxygen-related photoluminescence quenching in selectively grown GaN nanocolumns: Dependence on diameter

This work reports on the effects of air exposure on the photoluminescence intensity of GaN nanocolumns, with diameters ranging from below 40 nm up to around 230 nm, grown selectively on GaN/sapphire and GaN/Si(111). The high control of dimensions provided by selective area growth epitaxy allowed for a better study of the relationship between the observed phenomena, namely the photoluminescence intensity quenching due to oxygen photo-adsorption, and the nanocolumns properties (morphology and dimensions). For nanocolumns with diameters below 120 nm and lengths of about 300 nm, photoluminescence intensity dropped by more than 90% of the initial value, while for shorter nanocolumns a reduced drop value was found.     

含2个S副间隙6-SPS机构奇异性分析

6-SPS机构位姿矩阵采用四元数法描述,并将该矩阵和矢量坐标扩展为4维形式,推导出无间隙机构的运动方程,得到了机构运动的新型雅克比矩阵J_A和J_B;在此基础上,利用连续接触模型得到了两个含间隙S副共连杆和异杆时机构的运动系数矩阵。分别把各个运动系数的行列式展开,得到含间隙机构第一类奇异和第二类奇异的轨迹方程,利用MATLAB得到了机构在给定位置时的第一类位姿奇异轨迹和第二类位姿奇异三维轨迹曲面;通过将两类含间隙机构奇异轨迹曲面的比较,发现机构间隙对第二类奇异的影响大于对第一类奇异的影响;在两类奇异轨迹中,当S副异杆时,机构间隙的影响均大于S副共连杆时的影响。以无间隙机构奇异轨迹曲面上奇异点作为参考点,通过含间隙机构奇异轨迹曲面上与参考点相对应奇异点的相互比较,发现存在一个关于参考点的奇异域。     

山区输水管道工程的设计要点及陡坡直埋工艺

简要介绍了山区输水管道设计中常用的管道线路、管道材质、敷设方式、防冻方式及选取原则,重点介绍了一种适应山体陡坡段输水管直埋敷设的工艺。以供相关工程设计及施工人员借鉴。