偏转弹头导弹控制系统设计与仿真

根据弹头的可偏转特性,利用无根多刚体系统动力学方法建立了偏转弹头导弹的动力学模型,并对通道间的耦合特性及弹头偏转对弹体运动的影响进行了分析。在此基础上,将通道间的耦合及弹头偏转对弹体运动的影响作为干扰项处理,将气动参数的非线性变化等效为标称参数的摄动,利用变结构控制理论设计了偏转弹头导弹的控制器。仿真结果表明,所设计的变结构控制器能够有效地减小和消除俯仰、偏航通道对滚转通道的耦合作用以及弹头偏转对弹体运动的影响,较好地抑制了导弹气动参数的摄动,具有较高的稳态精度和良好的动态性能。     

谈语用教学中的情景运用

语用学的发展为语用的教学奠定了比较好的基础,语用的教学需要不断完善和发展;语用学的特点决定了语用教学的方法和教学方式的不同;语用教学中的情景运用主要包括课堂教师语言的情景运用、多媒体中的情景运用、课堂情景的组织运用。     

大型工程装备可拓制造模型研究

在大型工程装备快速变批量生产需求环境下,基于可拓协同制造资源概念,提出了装备可拓制造"超网络"链制造模式,研究了可拓制造能力单元的RKCQ流模型,构建了可拓制造"超网络"链的参考模型与组建过程模型,并指出使能技术框架体系,可拓制造"超网络"链模式提出的目的在于为大型工程装备制造系统应对不确定性的需求提供制造能力储备.     

基于几何无关模型的GNSS三频模糊度解算方法研究

针对模糊度估计受多径误差以及基线长度等影响而无法可靠保障运动情况复杂多变的动态测量问题,提出了一种新的三频模糊度动态快速求解算法。该方法利用模糊度估计成功率确定CIR法和LAMBDA法的适用范围。仿真及试验结果表明,该方法在保证模糊度估计可靠性的同时,还缩短了处理时间,适用于周围环境变化剧烈及载体运动情况复杂多变的实时动态测量。     

直升机静力试验杠杆加载系统的载荷配重计算方法

介绍了直升机静力试验加载杠杆系统配重计算的必要性，包括杠杆系统重心偏离合力中心而引起的后果以及消除该后果的处理方法。然后介绍了载荷系数法的原理以及在大型静力试验中的应用情况。结果表明，利用载荷系数法进行杠杆配重计算，并在加载合力点进行集中扣重，能够消除杠杆系统重量对试验加载的影响，保证试验加载精度。     

Joint Iterative Decoding for Network-Coding-Based Multisource LDPC-Coded Cooperative MIMO

A network-coding-based multisource LDPC-coded cooperative MIMO scheme is proposed,where multiple sources transmit their messages to the destination with the assistance from a single relay.The relay cooperates with multiple sources simultaneously via network-coding.It avoids the issues of imperfect frequency/timing synchronization and large transmission delay which may be introduced by frequency-division multiple access(FDMA)/code-division multiple access(CDMA)and time-division multiple access(TDMA)manners.The proposed joint″Min-Sum″iterative decoding is effectively carried out in the destination.Such a decoding algorithm agrees with the introduced equivalent joint Tanner graph which can be used to fully characterize LDPC codes employed by the sources and relay.Theoretical analysis and numerical simulation show that the proposed scheme with joint iterative decoding can achieve significant cooperation diversity gain.Furthermore,for the relay,compared with the cascade scheme,the proposed scheme has much lower complexity of LDPC-encoding and is easier to be implemented in the hardware with similar bit error rate(BER)performance.     

新兴媒体影响下的大学生思想状况调查研究

在全球化的文化背景下,公共传媒对传统的思想道德、文化底线产生着强大的冲击,而青年学生又是公共传媒的主要受众群体和组成部分。基于当前形势,针对新兴媒体对大学生思想政治教育所产生的影响开展了相应的调查和研究,提出了新形势下高校大学生思想政治教育的思路。调查结果显示:新兴媒体已经对大学生的学习、生活产生了较大的影响,高校应该开辟多种渠道以适应新兴媒体对高等院校思想政治教育所提出的新要求。     

基于CBI的大学英语拓展课程体系研究

以CBI为基本理论依据,探讨了大学英语拓展课程体系设置的基本思路和框架模块构建。从学生的英语水平和学习需求出发,通过把语言知识和学科知识相结合,使学生完成大学英语拓展阶段课程的学习,促进其语言水平和综合素养的全面提高。     

Enhanced multipath mitigation method based on multi-resolution CNR model and adaptive statistical test strategy for real-time kinematic PPP

This study proposes an enhanced multipath mitigation method based on multi-resolution carrier-to-noise-ratio (CNR) model and adaptive statistical test strategy for real-time kinematic precise point positioning (PPP) applications. The multi-resolution CNR model is established with GPS observation data collected from DOY 152 to 181 of 2019 by 230 globally distributed IGS stations, which used to analyze the relevant factors affecting CNR. Statistical results indicate that the CNR is not only related to the satellite elevation, but also closely related to the receiver types and specific satellite. The maximum difference between different receivers can reach 20 dB for the same satellite at the same elevation. In addition, the performance of the CNR is also obviously different between each satellite, and the maximum difference between different satellites is about 10 dB for the same receiver at the same elevation. Hence, in terms of the method which is based on CNR information for multipath detection and mitigation, the independence of receiver types, satellite and frequency must be considered. With the above analysis, this study developed a multi-resolution CNR model based on different receiver types, different satellites and different elevation firstly. Then, combined with the adaptive statistical test strategy which is based on the difference of CNR between inter-frequency and the difference of CNR between adjacent epochs, the multipath can be detected effectively. For the epoch which affected by multipath, the down-weighted strategy based on CNR is adopted to mitigate the influence of multipath on positioning. Real-time kinematic PPP data are collected to assess the proposed method, and the results demonstrate that the proposed method can detect the multipath effectively, and the detection rate can reach 90.28%. Moreover, after adopting the mitigation strategy, the RMS bias of the east, north and up components are improved about 19.95%, 17.89% and 23.07% compared to the original results, respectively. It is worth noting that this proposed method is also suitable for other GNSS, such as GLONASS and BDS, but the corresponding CNR model must be established simultaneously.     

超声辅助刻蚀对Ti3C2Tx微观结构的影响

二维层状材料MXene由于其独特的物理化学性质,受到了广泛关注。本文通过超声辅助刻蚀Ti_3AlC_2的方法制备了多层的Ti_3C_2T_x,利用X射线衍射仪、N_2吸脱附测试、扫描电子显微镜和透射电子显微镜对其微观结构的变化特征进行了详细的表征和分析,并与磁力搅拌刻蚀制备的Ti_3C_2T_x样品相对比。结果表明,与磁力搅拌刻蚀相比,超声辅助刻蚀可以进一步减小Ti_3C_2T_x平均薄层厚度和增加原子层间距,主要原因是超声处理能够促进未发生反应的薄片层中Al原子层的刻蚀。刻蚀过程中同一Al原子层有些区域先发生刻蚀,而一些区域依然存在Al原子。探明了附着在Ti_3C_2T_x表面几十纳米的颗粒是空间群为■的六方结构AlF_3,并且随着刻蚀时间的增加,其逐渐向非晶体转变。