水面舰艇规避鱼雷最优策略

规避机动是水面舰艇对鱼雷防御的基础和前提,通过对水面舰艇规避鱼雷过程的分析,建立了水面舰艇规避鱼雷的战术基础模型,并采用变分法进行解算,从所有可能的规避轨线中选取最优的规避轨线.水面舰艇规避鱼雷的战术基础模型,为水面舰艇防御鱼雷作战方案的仿真论证、防御鱼雷最优规避轨线的方案生成提供依据.对研究水面舰艇规避鱼雷战术具有一定的参考价值.     

基于李亚普诺夫最优反馈控制的中制导

基于李亚普诺夫最优反馈控制的2种实现方法,即时间最速下降法与空间最速下降法,提出了一种混合策略。应用于导弹中制导,获得了满意的结果,可以极大地缩短中制导飞行时间并大幅度地提高中制导末端速度。仿真结果表明,该方法有一定的工程应用参考价值。     

一种基于组合降维的图像识别方法

为克服图像识别中传统方法需要进行高维矩阵奇异值分解的困难,提出了先局部降维再总体降维的组合变换方法.ORL人脸图像数据库的实验表明,这一方法不仅减少了运算量,而且能较好地解决人脸这样一类复杂的图像识别问题;总体来说优于传统的基于KL变换的识别方法.     

Aircraft routing under the risk of detection

The deterministic problem for finding an aircraft's optimal risk trajectory in a threat environment has been formulated. The threat is associated with the risk of aircraft detection by radars or similar sensors. The model considers an aircraft's trajectory in three‐dimensional (3‐D) space and represents the aircraft by a symmetrical ellipsoid with the axis of symmetry directing the trajectory. Analytical and discrete optimization approaches for routing an aircraft with variable radar cross‐section (RCS) subject to a constraint on the trajectory length have been developed. Through techniques of Calculus of Variations, the analytical approach reduces the original risk optimization problem to a vectorial nonlinear differential equation. In the case of a single detecting installation, a solution to this equation is expressed by a quadrature. A network optimization approach reduces the original problem to the Constrained Shortest Path Problem (CSPP) for a 3‐D network. The CSPP has been solved for various ellipsoid shapes and different length constraints in cases with several radars. The impact of ellipsoid shape on the geometry of an optimal trajectory as well as the impact of variable RCS on the performance of a network optimization algorithm have been analyzed and illustrated by several numerical examples. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

飞船再入制导最佳反馈增益系数规律

为了获取基于标准轨道返回舱再入纵向制导的最佳反馈增益系数 ,建立了纵平面运动方程 ,推导了对应于纵向制导规律的摄动微分方程。根据Pontryagin极小值原理 ,给出了最优反馈控制律 ,求解Riccati方程 ,即可得到最佳反馈增益系数。考虑到实现的可行性 ,将时变的增益系数逼近成常数或分段常数 ,得到次优反馈增益系数 ,取得了满意的制导效果。     

三组元液体火箭发动机实现单级入轨的优化分析

建立了三组元液体火箭发动机性能计算模型、单级入轨可重复使用运载器质量模型和弹道模型,以起飞质量为目标函数,优化得到了实现单级入轨的发动机基本参数。结果显示:三组元发动机性能比氢氧发动机高10%。本研究是三组元发动机系统设计和分析的基础。     

截尾序贯验后加权检验截尾点的优化设计

选取截尾点是截尾序贯验后加权检验很关键的一步,目前理论上尚无有效的选取方法。本文用优化技术确定截尾点Ｃ,克服了实践中确定停时Ｎ和截尾点Ｃ遇到的计算困难,避免了一般取Ｃ＝１的盲目性,使截尾点Ｃ的选取有了理论根据。优选的截尾点不仅使双方承担的风险之和最小,而且使双方承担的风险值相对合理,易于接受。     

基于模糊推理规则的舰艇规避策略

应用模糊系统理论,给出了声纳报警时鱼雷速度、报警距离等信息不足条件下,舰艇有效规避自导鱼雷的数学模型和决策方法。     

Dynamic learning,pricing, and ordering by a censored newsvendor

We address the problem of determining optimal ordering and pricing policies in a finite‐horizon newsvendor model with unobservable lost sales. The demand distribution is price‐dependent and involves unknown parameters. We consider both the cases of perishable and nonperishable inventory. A very general class of demand functions is studied in this paper. We derive the optimal ordering and pricing policies as unique functions of the stocking factor (which is a linear transformation of the safety factor). An important expression is obtained for the marginal expected value of information. As a consequence, we show when lost sales are unobservable, with perishable inventory the optimal stocking factor is always at least as large as the one given by the single‐period model; however, if inventory is nonperishable, this result holds only under a strong condition. This expression also helps to explain why the optimal stocking factor of a period may not increase with the length of the problem. We compare this behavior with that of a full information model. We further examine the implications of the results to the special cases when demand uncertainty is described by additive and multiplicative models. For the additive case, we show that if demand is censored, the optimal policy is to order more as well as charge higher retail prices when compared to the policies in the single‐period model and the full information model. We also compare the optimal and myopic policies for the additive and multiplicative models. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

织女一号气象火箭设计中的若干技术

织女一号气象火箭是一种小型无控固体火箭,由于采用了若干先进的技术,使其总体性能达到了国际先进水平。本文介绍了其总体性能,重点介绍了总体方案设计中采用的包括最优推力程序等若干先进技术。