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991.
飞行器表面三维流场与固壁温度场的耦合分析 总被引:1,自引:0,他引:1
分析了飞行器表面温度场形成的物理机制,建立了飞行器蒙皮温度场耦合计算的理论模型,较为完整的考虑了各种热源对飞行器蒙皮温度的作用.采用有限体积法和重整化群RNG(Renormalization Group)k-ε湍流模型对流场求解N-S方程,蒙皮固壁中采用热传导模型,采用离散坐标法DOM(Discrete Ordinates Method)计算蒙皮固体壁面对外界大气的辐射.通过数值计算研究了飞行高度、马赫数和内热源对蒙皮温度分布的影响,以及高度及马赫数对飞行器表面气动加热的作用.结果表明,该方法适合考虑飞行器外部流场、固壁等多种热源作用的温度场数值模拟. 相似文献
992.
993.
With the increase of complexity of electromagnetic environment and continuous appearance of advanced system radars, signals received by radar reconnaissance receivers become even more intensive and complex. There- fore, traditional radar sorting methods based on neural network algorithms and support vector machine (SVM) cannot process them effectively. Aiming at solving this problem, a novel radar signal sorting method based on the cloud model theory and the geometric covering algorithm is proposed. By applying the geometric covering algo- rithm to divide input signals into different covering domains based on their distribution characteristics, the method can overcome a typical problem that it is easy for traditional sorting algorithms to fall into the local extrema due to the use of complex nonlinear equation to describe input signals. The method uses the cloud model to describe the membership degree between signals to be sorted and their covering domains, thus it avoids the disadvantage that traditional sorting methods based on hard clustering cannot deinterleave the signal samples with overlapped param- eters. Experimental results show that the presented method can effectively sort advanced system radar signals with overlapped parameters in complex electromagnetic environment. 相似文献
994.
航空发动机的放气活门调节规律是一个较为复杂的控制过程。依据大量QAR数据,采用数学分析的方法初步探索了PW4077D型发动机2.5级放气活门开度控制规律。通过对大量数据的统计分析可知,放气活门开度与低压转子转速N1关系最为密切。首先通过数据解码和修正得到各航班标准状态下的N1值;采用非线性回归的数理统计方法分段拟合,得到2.5级放气活门开度与N1的数学模型。经检验,该模型在一定范围内良好地反映了该型发动机2.5级放气活门开度大小的调节规律。 相似文献
995.
青年学生的德育培养是思想政治工作的一项重要而紧迫的任务,本文阐述了“八荣八耻”社会主义荣辱观对青年学生道德培养的现实意义和深远影响,以及在培养青年学生的优良品质上学校和社会的重要责任。 相似文献
996.
For maritime radiation source target tracking in particular electronic counter measures(ECM)environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frst problem is the poor observability of the radiation source.The second one is the measurement uncertainty which includes the uncertainty of the target appearing/disappearing and the detection uncertainty(false and missed detections).A novel approach is proposed in this paper for tracking maritime radiation source in the presence of measurement uncertainty.To solve the poor observability of maritime radiation source target,using the radiation source motion restriction,the observer altitude information is incorporated into the bearings-only tracking(BOT)method to obtain the unique target localization.Then the two uncertainties in the ECM environment are modeled by the random fnite set(RFS)theory and the Bernoulli fltering method with the observer altitude is adopted to solve the tracking problem of maritime radiation source in such context.Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source,and also demonstrate the superiority of the method compared with the traditional integrated probabilistic data association(IPDA)method.The tracking performance under different conditions,particularly those involving different duration of radiation source opening and switching-off,indicates that the method to solve our problem is robust and effective. 相似文献
997.
Canonical correlation analysis ( CCA ) based methods for low-resolution ( LR ) face recognition involve face images with different resolutions ( or multi-resolutions ), i.e.LR and high-resolution ( HR ) .For single-resolution face recognition , researchers have shown that utilizing spatial information is beneficial to improving the recognition accuracy , mainly because the pixels of each face are not independent but spatially correlated.However , for a multi-resolution scenario , there are no related works.Therefore , a method named spatial regularization of canonical correlation analysis ( SRCCA ) is developed for LR face recognition to improve the performance of CCA by the regularization utilizing spatial information of different resolution faces.Furthermore , the impact of LR and HR spatial regularization terms on LR face recognition is analyzed through experiments. 相似文献
998.
在虚拟仪器技术进步的过程中,由于需求的复杂性、成本的限制、技术生命期和设备寿命期等诸多因素的共同作用,新、老技术并存的情况必然存在,所以研究ATS的升级问题是一项具有现实意义和经济价值的工作.介绍了一种基于混合总线的自动测试系统升级设计,从硬件和软件两个方面详细说明了系统的实现过程.系统从硬件系统设计到软件开发都遵循了标准化和通用化的设计思想. 相似文献
999.
强实时条件下光纤通道仲裁环带宽分配方法 总被引:7,自引:0,他引:7
光纤通道是一个为适应高性能信息传输要求而提出的计算机通讯协议,仲裁环是光纤通道的基本拓扑结构之一.为解决网络消息集实时发送的问题,研究了光纤通道仲裁环拓扑在强实时条件下的通信性能.依据实时系统中的周期任务模型和光纤通道仲裁环协议规定的访问公平机制,采用负载匹配算法提出了一种适用于仲裁环网络的带宽分配方法.推导并证明了采用该方法时在最坏情况下消息集强实时的网络可达负载率不低于50%. 相似文献
1000.