恒速偏频激光陀螺系统航向敏感误差的在线标定与补偿

以单轴恒速偏频激光陀螺系统为研究对象,建立了静基座初始对准时系统中标定参数变化误差对航向敏感误差影响的数学模型。为克服外场测试环境下难以分别精确估计各标定参数的限制,提出将安装关系矩阵参数误差对航向敏感误差的作用视为一个整体进行标定;不需要外部基准,即可基于最小二乘算法实现航向敏感误差系数的在线标定。采用标定得到的航向敏感误差系数,利用原理样机进行了在线补偿精度实验测试。实验结果表明,所提出的在线标定与补偿方法能够有效消除航向敏感误差,提高初始对准航向角精度。     

转子动不平衡条件下的末制导炮弹弹道特性

针对因工艺导致的惯导陀螺存在不平衡质量的问题,讨论了转子在不平衡力偶作用下的运动特性。通过建立转子形体坐标系、惯性主轴坐标系以确定转子主轴相对惯性空间的方位,并分析了转子定向性的变化对惯导飞行控制过程的影响。同时,利用末制导炮弹刚体弹道模型进行了仿真,结果表明:转子铅垂方向以及水平方向的动不平衡角对末制导炮弹的射程和侧偏具有重要的影响。     

含内置式耐压液舱舱段耐压船体结构应力分析

为研究静压下内置式耐压液舱结构的力学规律,采用有限元方法对内置式耐压液舱及船体结构进行强度计算,分析了不同工况下耐压壳的变形和应力特征,比较了不同区域耐压壳的应力情况。结果表明:液舱内外相连通时的工况更危险,耐压壳应力水平也更高。同时,内置式耐压液舱的存在使液舱底部耐压壳的应力水平高于耐压壳其他区域。该研究结果可为内置式耐压液舱结构设计提供指导。     

Signal‐to‐interference‐plus‐noise ratio estimation for wireless communication systems: Methods and analysis

The Signal‐to‐Interference‐plus‐Noise Ratio (SINR) is an important metric of wireless communication link quality. SINR estimates have several important applications. These include optimizing the transmit power level for a target quality of service, assisting with handoff decisions and dynamically adapting the data rate for wireless Internet applications. Accurate SINR estimation provides for both a more efficient system and a higher user‐perceived quality of service. In this paper, we develop new SINR estimators and compare their mean squared error (MSE) performance. We show that our new estimators dominate estimators that have previously appeared in the literature with respect to MSE. The sequence of transmitted bits in wireless communication systems consists of both pilot bits (which are known both to the transmitter and receiver) and user bits (which are known only by the transmitter). The SINR estimators we consider alternatively depend exclusively on pilot bits, exclusively on user bits, or simultaneously use both pilot and user bits. In addition, we consider estimators that utilize smoothing and feedback mechanisms. Smoothed estimators are motivated by the fact that the interference component of the SINR changes relatively slowly with time, typically with the addition or departure of a user to the system. Feedback estimators are motivated by the fact that receivers typically decode bits correctly with a very high probability, and therefore user bits can be thought of as quasipilot bits. For each estimator discussed, we derive an exact or approximate formula for its MSE. Satterthwaite approximations, noncentral F distributions (singly and doubly) and distribution theory of quadratic forms are the key statistical tools used in developing the MSE formulas. In the case of approximate MSE formulas, we validate their accuracy using simulation techniques. The approximate MSE formulas, of interest in their own right for comparing the quality of the estimators, are also used for optimally combining estimators. In particular, we derive optimal weights for linearly combining an estimator based on pilot bits with an estimator based on user bits. The optimal weights depend on the MSE of the two estimators being combined, and thus the accurate approximate MSE formulas can conveniently be used. The optimal weights also depend on the unknown SINR, and therefore need to be estimated in order to construct a useable combined estimator. The impact on the MSE of the combined estimator due to estimating the weights is examined. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

考虑Reissner效应的功能梯度柱壳裂纹高阶渐近场

针对考虑Reissner效应的功能梯度柱壳裂纹问题,通过分离变量和级数展开法构造广义位移函数,求得了裂纹尖端高阶渐近场。结果表明：该解类似于Williams解,为此类问题的特征函数,能够描述此类材料各种含裂纹结构的整个应力场和位移场;材料非均匀性对高阶项有显著影响。     

某型火炮制退机节制环磨损故障分析与处理

制退机的性能好坏直接关系到火炮作战效能的发挥。针对目前装备保障方式大多停留在维修层面而理论研究不够深入的实际,对节制环磨损故障的机理进行分析。以某型火炮短节制杆式制退复进机为对象,利用MATLAB数值计算平台,编程仿真节制环磨损故障对后坐的影响。同时探讨了故障后对火炮的处理方案。研究表明,节制环磨损对后坐诸元都将产生不同影响,针对影响的程度可制定相应的故障处理方案。仿真模拟和方案探讨对装备保障工作具有参考意义。     

联合编队作战行动方案建模

研究联合编队的作战行动方案问题,首先需要建立合理的任务模型。在基本作战样式基础上,针对联合编队任务特点,设计了一种联合编队作战行动方案的建模方法。该模型包含对海攻击和对空防御等5种基本作战样式,结合规划和调度两方面的特点,提供了资源和系统状态的描述机制。实例证明建模方案不仅具有可行性,而且丰富了作战行动方案的建模理论,对联合编队作战系统的研究、决策和建设具有一定的参考价值。     

纵桁对环肋圆柱壳体水下振动与声辐射的影响

采用结构有限元耦合流体边界元的附加质量附加阻尼算法,对具有不同数量纵桁的加筋环肋圆柱壳水下振动与声辐射噪声进行了数值计算,并对数值计算结果进行了初步的比较和分析,讨论了纵桁的数量对圆柱壳水下振动与声辐射的影响.结果表明:纵桁对圆柱壳水下的减振降噪有较好的效果,并且纵桁的数量越多,减振降噪效果越好,但增加纵桁的数量也相应增加了艇体的重量,在潜艇结构设计时须在降噪及艇体重量间综合权衡.     

轴向冲击载荷下圆柱壳的塑性动力屈曲

对于轴向冲击载荷下圆柱壳的轴对称塑性动力屈曲问题,将临界应力和屈曲惯性项指数参数作为双特征参数求解.由相邻平衡准则导出失稳控制方程、边界条件和波阵面上的连续条件.由失稳瞬间的能量转换和守恒准则,导出波阵面上的一个屈曲变形约束方程.由此得出定量求解2个特征参数和动力屈曲模态的完备定解条件.关于屈曲应力和屈曲波数的理论计算结果与已有实验吻合良好.     

加肋凹锥-环-柱结合壳结构参数分析

采用分区样条等参元法,分析了加肋凹锥 环 柱结合壳的应力和稳定性特点,研究了各项结构参数变化对结合壳应力和稳定性的影响,认为加肋凹锥 环 柱结合壳能有效降低锥柱结合部的纵向弯曲应力,但对于降低环向应力效果有限,建议在环壳段中部增加一档肋骨;半锥角的凹结合壳越大,嵌入环壳段的优势越明显;增大环壳与柱壳半径比可以有效降低环壳段中部的纵向弯曲应力.