Semi-analytic Solution of Steady Temperature Fields During Thin Plate Welding

Usually, it is very difficult to find out an analytical solution to thermal conduction problems during high temperature welding. Therefore, as an important numerical approach, the method of lines (MOLs) is introduced to solve the temperature field characterized by high gradients. The basic idea of the method is to semi-discretize the governing equation of the problem into a system of ordinary dif-ferential equations (ODEs) defined on discrete lines by means of the finite difference method, by which the thermal boundary condition with high gradients are directly embodied in formulation. Thus the temperature field can be obtained by solving the ODEs. As a numeri-cal example, the variation of an axisymmetrical temperature field along the plate thickness can be obtained.     

Hall MHD reconnection with an initial guide field By0

An uniform out-of-plane magnetic field component B_y0 is added to the equilibrium Harris sheet with plasma β = 0.5 and L_c = 0.5d_i (where L_c is the half-width of the equilibrium current layer and d_i is the ion inertial length). Driven by the continuous boundary inflows, the magnetic reconnections with the guide field B_y0/B₀ ranging from 0 to 4.0 are investigated using a 2.5D Hall magnetohydro-dynamic (MHD) code developed from a multi-step implicit scheme. The features of the reconnection field are substantially altered in the presence of the guide field. The openness of the magnetic separatrix angle is slightly reduced and the anti-symmetric quadrupolar structure of B_y field and the symmetric distribution of plasma pressure P are replaced by an asymmetric B_y four-wing structure and an asymmetric P plot as a non-zero B_y0 is added. The decoupling of electrons and ions also occurs near the X line in the case with a finite B_y0, but the effect of initial B_y0 on the electron flow is greater than that on the ion flow. The reconnection rates at the X-line drops from 0.151 to 0.06, namely, ∂A/∂t is reduced by a factor of 2.5 as B_y0/B₀ increases from 0 to 4.0. The reduction of reconnection rate might be related to the reducing openness of reconnection layer with the increasing B_y0.     

浅论红色文化产品的创新设计与价值实现——以河北省为例

本文通过对红色文化领域物质与精神两方面产品的研发现状与经验的分析,结合未来设计领域的发展趋势,提出开发体验性和个性化的红色文化产品。以河北省为例,探讨如何在实现红色文化产品的价值同时,更好的使红色文化为当代精神文明建设服务。     

Planetary Magnetic Dynamo Effect on Atmospheric Protection of Early Earth and Mars

In light of assessing the habitability of Mars, we examine the impact of the magnetic field on the atmosphere. When there is a magnetic field, the atmosphere is protected from erosion by solar wind. The magnetic field ensures the maintenance of a dense atmosphere, necessary for liquid water to exist on the surface of Mars. We also examine the impact of the rotation of Mars on the magnetic field. When the magnetic field of Mars ceased to exist (about 4 Gyr ago), atmospheric escape induced by solar wind began. We consider scenarios which could ultimately lead to a decrease of atmospheric pressure to the presently observed value of 7 mbar: a much weaker early martian magnetic field, a late onset of the dynamo, and high erosion rates of a denser early atmosphere.     

一种热电势的简易表达法

当具有不同温度分布的多种导体连接在一个环路中时,按照帕尔贴电势和汤姆逊电势分析环路中的总的热电势是困难的。选择一些导体作为标准电极,就能把总的热电势分成一系列单一导体的独立热电势,用这个方法,分析工作将变得十分简单。     

航天电连接器的选用

为确保航天系统工程广泛使用的重要配套接口元件－－电连接器的使用可靠性，详细介绍了其选用的一般要求和特殊要求，各项技术参数（电参数、安全参数、环境参数等）的选择方法，最后讨论了电连接器在使用前和使用过程中的注意事项。     

航天电子产品整机的装联布线

文章介绍了航天电子产品整机装联布线的原则、注意要点、方法、顺序及常见问题的处理。     

某型飞机导航误差对CCD稳瞄系统目标搜索域的影响

分析了DG-1型多普勒／GPS组合导航系统，在不同工作方式下导航误差所引起的搜索方位角的误差；讨论了由于搜索方位角的变化引起的搜索域的变化。通过对机理的研究提出了解决办法。     

双翼金属圆柱体散射场的整体计算

本文利用keller的几何绕射理论（GTD）推求出双翼金属圆柱体散射场高频快收敛整体解，弥补了传统分离解（把系统分解为一个金属圆柱和两个金属半平面，分别求解再简单迭加）的不足之处，最后，给出了整体解和分离解的散射电场的模值数值计算结果。     

电子回旋共振中和器内静磁场及微波电磁场的数值计算

为了研究电子回旋共振中和器内静磁场和微波电磁场的分布规律,设计合理的磁路结构以形成电子回旋共振区,并使微波强电场区与电子回旋共振区重合,采用有限元分析软件对中和器内的静磁场和微波电磁场进行了数值计算。计算结果表明:永磁体及磁轭的尺寸均影响电子回旋共振区的分布;天线伸入长度越长,微波电场越强。微波频率为4.2GHz时,六块相同的长12mm,宽8mm,高5mm的条形永磁铁与磁轭组成的磁路结构,可以产生合理的电子回旋共振区。L型天线伸入长度为5mm时微波强电场区可与电子回旋共振区重合。