变电站导线力学计算软件设计

本文简单介绍了导线拉力计算对变电站设计中的重要性,原有导线拉力计算软件的不足。详细分拆了新版导线拉力计算软件的设计过程及技术特性。对新版导线拉力计算软件的使用作了详尽的说明。

架空配电线路导线力学特性计算

架空配电线路导线的力学特性不仅应符合相关国标的规定,还应满足运行档距的要求。文章就天津郊区架空导线跨越河道大档距设计时采用钢芯绝缘导线为例,进行导线力学特性计算。

基于VB的高压架空送电线路的导线力学计算

应用VB语言编程实现高压架空送电线路导线机械计算,讨论了状态方程求解方法的选择,阐述了控制气象条件的确定方法,给出临界档距以及适合实际工程应用的放线曲线的应力、弧垂的计算公式。提高了架空线路工程设计的速度和精度,最后通过工程上的具体实例对所编制的软件加以验证和说明。

Effect of Zr and Sc on mechanical properties and electrical conductivities of Al wires

In order to obtain the Al wires with good mechanical properties and high electrical conductivities, conductive wires of Al-0.16 Zr, Al-0.16 Sc, Al-0.12Sc-0.04Zr（mass fraction, %） and pure Al（99.996%） were produced with the diameter of 9.5 mm by continuous rheo-extrusion technology, and the extruded materials were heat treated and analyzed. The results show that the separate additions of 0.16% Sc and 0.16% Zr to pure Al improve the ultimate tensile strength but reduce the electrical conductivity, and the similar trend is found in the Al-0.12Sc-0.04 Zr alloy. After the subsequent heat treatment, the wire with the optimum comprehensive properties is Al-0.12Sc-0.04 Zr alloy, of which the ultimate tensile strength and electrical conductivity reach 160 MPa and 64.03%（IACS）, respectively.

输电线路覆冰监测新技术研究

针对现有输电线路覆冰监测方法的不足,提出了利用机载激光扫监测输电线路的导线覆冰厚度。首先研究了LiDAR点集分类理论和导线空间位置的提取算法,然后根据监测获得导线覆冰前后的弧垂变化量,结合导线力学分析模型建立导线覆冰厚度精细分析模型。最后对导线覆冰监测厚度与现场实测厚度结果进行一致性分析,验证该方法的可行性和准确性。

Nonlinear characteristics of induced spontaneous combustion process of sulfide ores

To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 ℃, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages： incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0 ~C/min, 2.0 ~C/min and 4.2 ~C/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.

Dynamics of phase transformation of Cu-Ni-Si alloy with super-high strength and high conductivity during aging

The precipitation behaviors of the Cu-Ni-Si alloys during aging were studied by analyzing the variations of electric conductivity.The Avrami-equation of phase transformation kinetics and the Avrami-equation of electric conductivity during aging were established for Cu-Ni-Si alloys,on the basis of linear relationship between the electric conductivity and the volume fraction of precipitates,and the calculation results coincide well with the experiment ones.The transformation kinetics curves were established to characterize the aging process.The characteristics of precipitates in the supersaturated solid solution alloy aged at 723 K were established,and the results show that the precipitates areβ-Ni3Si andδ-Ni2Si phases.

Non-linear Dynamics Method to Angles-Only Navigation for Non-cooperative Rendezvous of Spacecraft

Aiming at the problem of relative navigation for non-cooperative rendezvous of spacecraft,this paper proposes a new angles-only navigation architecture using non-linear dynamics method. This method does not solve the problem of poor observability of angles-only navigation through orbital or attitude maneuvering,but improves the observability of angles-only navigation through capturing the non-linearity of the system in the evolution of relative motion. First,three relative dynamics models and their corresponding line-of-sight(LoS)measurement equations are introduced,including the rectilinear state relative dynamics model,the curvilinear state relative dynamics model,and the relative orbital elements(ROE)state relative dynamics model. Then,an observability analysis theory based on the Gramian matrix is introduced to determine which relative dynamics model could maximize the observability of angles-only navigation. Next,an adaptive extended Kalman filtering scheme is proposed to solve the problem that the angles-only navigation filter using the non-linear dynamics method is sensitive to measurement noises. Finally,the performances of the proposed angles-only navigation architecture are tested by means of numerical simulations,which demonstrates that the angles-only navigation filtering scheme without orbital or attitude maneuvering is completely feasible through improving the modeling of the relative dynamics and LoS measurement equations.

Theoretical Analysis and Experimental Evidence of Non-Fourier Heat Conduction Behavior

This paper consists of two parts. (1) For a hollow sphere with sudden temperature changes on its inner and outer surfaces, the hyperbolic heat conduction equation is employed to describe this extreme thermal case and an analytical expression of its temperature distribution is obtained. According to the expression, the non-Fourier heat conduction behavior that will appear in the hollow sphere is studied and some qualitative conditions that will result in distinct non-Fourier behavior in the medium is ultimately attained. (2) A novel experiment to observe non-Fourier heat conduction behavior in porous material (mainly ordinary duplicating paper) heated by a microsecond laser pulse is presented. The conditions for observing distinct non-Fourier heat conduction behavior in the experimental sample agree well with the theoretical results qualitatively.

Modulating the thermal conductivity of silicon nanowires via surface amorphization

We perform non-equilibrium molecular dynamics calculations to study the heat transport in crystalline-core amorphous-shell silicon nanowires(SiNWs).It is found that the thermal conductivity of the core-shell SiNWs is closely related to the cross-sectional area ratio of amorphous shell.Through shell amorphization,an 80%reduction in thermal conductivity compared to crystalline SiNWs with the same size can be achieved,due to the non-propagating heat diffusion in the amorphous region.In contrast to the strong temperature-dependent thermal conductivity of crystalline SiNWs,the core-shell SiNWs only show weak temperature dependence.In addition,an empirical relation is proposed to accurately predict the thermal conductivity of the core-shell SiNWs based on the rule of mixture.The present work demonstrates that SiNWs with an amorphized shell are promising candidates for thermoelectric applications.