考虑刚度影响的双输入转矩分流式齿轮系统均载特性

为了对转矩分流齿轮系统均载特性进行更加深入的研究,建立系统非线性动力学模型,采用数值仿真方法计算系统的均载系数,分析联动轴扭转刚度、输出轴支撑刚度、输入转速以及轴位角对均载系数的影响规律,并对齿轮系统进行实验研究。研究结果表明:输出端的均载系数大于输入端的均载系数,高压输入端的均载系数大于低压输入端的均载系数;均载系数随联动轴扭转刚度的增加而增加,随支撑刚度的增加先减小后平缓;在不同转速下均载系数呈现波动变化,在4 100 ~ 4 400 r/min输入转速区间出现了谐振峰;轴位角a₂的值会影响均载系数随a₁变化的规律,尽可能减小轴位角可以提高系统的均载性能。通过实验测试验证了本文分析模型的正确性。     

复合材料层合板疲劳寿命形状参数与门槛值分析方法

复合材料性能具有较大的分散性,在表征复合材料疲劳寿命时,必须考虑分散性的影响。以M21C复合材料开孔层合板为研究对象,采用Sendeckyj等效静强度模型和随机变量函数的概率分布方法推导了复合材料层合板疲劳寿命形状参数和剩余强度形状参数的关系,通过试验和统计的方法获得了M21C复合材料开孔层合板的疲劳寿命形状参数和疲劳门槛值,对载荷放大系数以及低载截除水平的确定提供了数据支持。     

救生伞背带参数对假人动载的影响研究

针对救生伞假人高速开伞空投试验,建立降落伞-背带-假人系统的动力学模型,分析背带及脱离锁参数对假人质心过载的影响。在合理简化的基础上,采用多体动力学方法建立降落伞、背带脱离锁和假人的十五自由度动力学模型;采用质量-阻尼弹簧模型建立背带模型,连接降落伞、脱离锁和假人;利用实测过载计算降落伞开伞力。利用所建立的动力学模型仿真典型状态下假人和背带的动力学响应,验证所建立模型的合理性。分析脱离锁位置、背带松紧程度、背带材料特性对假人质心最大过载的影响,用于指导背带设计以及确定最佳的背带脱离锁位置。     

救生伞背带分系统对假人动载的影响

为了改善救生伞背带分系统的安全性,建立降落伞-背带-假人系统的动力学模型,分析背带及脱离锁参数对假人质心过载的影响。针对救生伞假人高速开伞空投试验,采用多体动力学方法建立降落伞、背带脱离锁和假人的十五自由度动力学模型;采用半质量-阻尼弹簧模型建立背带模型,连接降落伞、脱离锁和假人;利用实测过载计算降落伞开伞力。利用所建立的动力学模型仿真典型状态下假人和背带的动力学响应,验证所建立模型的合理性。分析了脱离锁位置、背带松紧程度、背带材料特性对假人质心最大过载的影响,可用于指导背带设计以及确定最佳的背带脱离锁位置。     

可实现以期望角度过顶迂回打击的制导律设计

在已有的小型导弹角度约束制导律设计中,对敌方目标打击角度约束范围往往有限.为了扩大角度约束的可行范围,实现对目标的全方位打击,基于双圆弧原理设计了可实现过顶迂回打击的制导律.首先,建立了导弹的末制导段相对运动模型,然后对双圆弧曲线拟合的原理进行了介绍和推导证明,对于两段圆弧的关键参数进行了推导,最后基于该原理设计了一种...     

Dynamic parameters of multi-cabin protective structure subjected to low-impact load – Numerical and experimental investigations

The dynamic response of a multi-cabin protective structure subjected to impact load directly affects the protective performance of materials; thus, studying the dynamic response and communication law of wave effect of the load plays an important role in the prediction of protective performance. In this study, the protection experiments of box-structure under air- and/or water-medium are conducted, the dynamic response of the structure subjected to low-impact load is analyzed, and the corresponding numerical simulations are analyzed using the theory of finite element method (FEM). Combined with experimental and FEM simulations, the shock strain distribution, acceleration attenuation, and signal energy in defensive materials are determined. Based on the results, the metal structure exhibits good absorption characteristics for shock vibration. Using the experimental data, we also show that the attenuation of shock wave in water medium should be significantly better than that in air medium, and the protective structure should be designed for a combination of water and air mediums. Meanwhile, the numerical simulation can provide a quantitative analysis process for dynamic analysis of defensive materials.     

某家具城火灾危险性研究

对西部家具城进行现场调研,了解其建筑概况以及内部可燃物种类、材质、数量等,统计火灾荷载,对其潜在的火灾危险性进行分析,提出减少火灾荷载、明确疏散路线和出入口、加强火源管理、提高消防安全意识等防火措施。     

舰船电力系统运行负荷估算方法研究

针对舰船电力系统的运行负荷估算常见算法的不足,提出了改进算法.改进算法用随机模型和回归模型描述舰船电力负荷,用回归模型描述的负荷采用回归算法,用随机模型描述的负荷采用逐步聚类法进行计算,并对获得随机负荷的计算参数提出了具体方法.通过对某船的计算和实测,进行了各算法的比较,验证了改进算法的可信性.     

军体课程密度与运动负荷初探

对军事体育课中运动负荷与课的密度进行研究,阐述了军事体育课合理运用课的密度与运动负荷的重要性,为进一步深化军事体育训练提供借鉴。     

“This program will not be a threat to them”: Ballistic Missile Defense and US relations with Russia and China

Although the Obama Administration has differed from its predecessor in a number of respects, on the specific issue of Ballistic Missile Defense (BMD), there is a striking continuity. The Obama Administration has remained committed to the BMD project, even as it has modified the schedule of deployments and prioritized different systems from the Bush Administration. Significantly, this has led to Chinese and Russian balancing in the nuclear sphere. As a result, there is evidence of a security dilemma-type dynamics in US relations with China and Russia. At present, there is no study that analyzes Russian and Chinese hard internal balancing against the USA in the sphere of missile defense during the Obama Administration. This article fills this gap.