旋转弹用横滚隔离捷联惯导稳定回路设计

旋转火箭弹高速自旋的特点限制了传统惯性导航系统在旋转弹上的应用,针对此问题研究了一种具有横滚隔离功能的捷联惯性导航系统.通过引入一个与自旋轴平行的隔离环可避免横滚轴向陀螺输出饱和,同时可极大的减少陀螺刻度系数误差及安装偏差引起的测量误差.着重研究了隔离环稳定回路的一种校正方案,通过采用超前滞后网络对横滚隔离光纤捷联惯导稳定回路进行校正.仿真结果表明稳定回路可有效跟踪阶跃信号,系统超调量小于,调节时间小于0.15 s;在2N·m常值干扰力矩作用下,平台稳态偏差角为0.67′.该方案具有一定的工程实用价值.     

利用红外热像技术快速预测材料的S-N曲线

研究材料疲劳一般采用试验的方法,但试验周期长, 所需试验试件和费用多,一直以来都是材料疲劳试验难以克服的困难,人们一直在探寻能快速得到材料疲劳性能的方法.本文在前人研究的基础上,采用红外热像技术,确定了材料的疲劳极限,并在"同种试件疲劳破坏消耗的塑性功不变"的假设下,通过建立塑性温升、热耗散、塑性功之间的关系给出了试件疲劳寿命的计算公式.由此经过简单的试验,理论上用一根试件,试验几个小时就可以快速确定材料的疲劳寿命,给出材料的S-N曲线.     

Mechanism of unsteady aerodynamic heating with sudden change in surface temperature

The characteristics and mechanism of unsteady aerodynamic heating of a transient hypersonic boundary layer caused by a sudden change in surface temperature are studied. The complete time history of wall heat flux is presented with both analytical and numerical approaches. With the analytical method, the unsteady compressible boundary layer equation is solved. In the neighborhood of the initial and final steady states, the transient responses can be expressed with a steady-state solution plus a perturbation series. By combining these two solutions, a complete solution in the entire time domain is achieved. In the region in which the analytical approach is applicable, numerical results are in good agreement with the analytical results, showing reliability of the methods. The result shows two distinct features of the unsteady response. In a short period just after a sudden increase in the wall temperature, the direction of the wall heat flux is reverted, and a new inflexion near the wall occurs in the profile of the thermal boundary layer. This is a typical unsteady characteristic. However, these unsteady responses only exist in a very short period in hypersonic flows, meaning that, in a long-term aerodynamic heating process considering only unsteady surface temperature, the unsteady characteristics of the flow can be ignored, and the traditional quasi-steady aerodynamic heating prediction methods are still valid.     

SELF-INSTABILITY AND BENDING BEHAVIORS OF NANO PLATES

This paper aims at investigating the size-dependent self-buckling and bending behaviors of nano plates through incorporating surface elasticity into the elasticity with residual stress fields. In the absence of external loading, positive surface tension induces a compressive residual stress field in the bulk of the nano plate and there may be self-equilibrium states corresponding to the plate self-buckling. The self-instability of nano plates is investigated and the critical self-instability size of simply supported rectangular nano plates is determined. In addition, the residual stress field in the bulk of the nano plate is usually neglected in the existing literatures, where the elastic response of the bulk is often described by the classical Hooke＇s law. The present paper considered the effect of the residual stress in the bulk induced by surface tension and adopted the elasticity with residual stress fields to study the bending behaviors of nano plates without buckling. The present results show that the surface effects only modify the coefficients in corresponding equations of the classical Kirchhoff plate theory.     

Weyl群的子群结构

对各种类型的不可约根系,讨论了其Ｗｅｙｌ群一类子群的极大性。     

Extinc非自治竞争Lotka- Volterra系统的灭绝性(英文)

研究了几个种群非自治 L otka- Volterra竞争系统 ,给出了竞争的 n个种群中任意 r个持续生存而 n- r个灭绝的一类充分条件     

一类k步k+2阶解刚性微分方程的混杂法

构造了一类带参数的k步k+2阶混杂方法,讨论了该方法的稳定性质．并给出了与其等价的二阶导数方法．数值实例说明,这类方法更适合求解非线性Stiff问题,对高震荡问题亦会更有效．     

冲击荷载作用下深埋洞室稳定性分析

建立了反映高应力状态下岩石材料塑性变形及损伤破坏的弹塑性损伤本构模型。通过ABAQUS显式有限元计算程序及其二次开发平台,使用FORTRAN语言编制本构计算程序,将本构模型导入ABAQUS计算软件当中。将本文提出的岩石材料弹塑性损伤本构模型应用于深埋地下洞室受冲击地压作用问题的计算分析。计算分析结果说明:在应力较低时,受冲击作用后的洞室围岩表现出明显的脆性开裂破坏特征;随着地应力水平的提高,围岩变形及承受冲击荷载的能力均明显变大,洞室在发生较大塑性变形后才出现整体性破坏。     

如何调控经济金融化？——基于中国经济的三方演化博弈视角

十九大以来,中国的改革开放进程不断加快,在金融领域体制改革也是不断深化,开放程度不断提高,期间实体经济金融化的问题在我国日益凸显,经济“脱实向虚”的现象愈发严重,而实体经济能否健康发展将决定一个国家综合国力的强弱。因此,通过研究实体企业金融化问题来探讨中国防范产业“空心化”的策略非常必要。运用演化博弈和模拟仿真的方法,构建基于政府监管部门、实体企业和金融企业金融化的三方演化博弈分析框架,重点分析政府监管对企业策略选择的影响,并对演化均衡过程进行模拟仿真。研究表明,政府对企业所采取措施譬如加大处罚、提高减税幅度或补贴等对促进实体企业和金融企业达成合作关系有积极作用,实体企业和金融企业对分利技术水平和社会禀赋倍增率的变化敏感。     

生成函数在稳定常数测定中的应用

介绍生成函数法的分类、基本原理、测定方法、各种方法的特点及应用实例。