基于历史数据的测试任务约简和故障诊断

针对部队航电组件测试任务繁重、故障定位率低的问题,提出一种利用历史数据来简化测试任务、提高故障定位率的方法。利用粗糙集信息系统理论,建立了航电组件故障信息系统模型;基于测试任务辨识函数和诊断允许误差对测试任务进行约简;基于最短测试时间选出最优测试任务集;利用贝叶斯最大后验概率进行故障诊断推理,将诊断问题归结为不等式约束极值问题;用0-1规划隐数算法求得最优解。最后以某型飞机惯导部件为例验证了方法的快速有效性。     

Calibration method of phase distortions for cross polarization channel of instantaneous polarization radar system

A novel poladmetric calibration method for new target property measurement radar system is presented.Its application in the real radar system is also discussed.The analysis indicates that instantaneous polarization radar (IPR) has inherent cross-polarization measurement error.The proposed method can effectively eliminate this error,and thus enhance the polarization scattering matrix (PSM) measurement precision.The phase error caused by digital receiver's direct iF sampling and mixing of two orthogonal polarization channels can be removed.Consequently,the inherent error of target polarization scattering measurement of the instantaneous polarization radar system is well revised.It has good reference value for further plcarimetric calibration and high practical application prospect.     

Secure and efficient elliptic curve cryptography resists side-channel attacks

An embedded cryptosystem needs higher reconfiguration capability and security. After analyzing the newly emerging side-channel attacks on elliptic curve cryptosystem (ECC), an efficient fractional width-w NAF (FWNAF) algorithm is proposed to secure ECC scalar multiplication from these attacks. This algorithm adopts the fractional window method and probabilistic SPA scheme to recondigure the pre-computed table, and it allows designers to make a dynamic configuration on pre-computed table. And then, it is enhanced to resist SPA, DPA, RPA and ZPA attacks by using the random masking method. Compared with the WBRIP and EBRIP methods, our proposals has the lowest total computation cost and reduce the shake phenomenon due to sharp fluctuation on computation performance.     

质子交换膜燃料电池温度的MPC控制

根据PEMFC热量传递机理建立电堆温度的simulink模型,由于实验模型属于非线性模型,很难对其设计控制器,因此在工作点附近将系统线性展开得到其线性模型.针对线性模型设计MPC控制器,调整得到合理参数后,利用此MPC控制器调节电堆温度模型的控制输入,得到对电堆温度的理想控制效果.     

一种新型射频识别读写器天线的仿真与设计

提出了一种由两组正交放置的双L天线构成的新型圆极化射频识别读写器天线,有效地克服了平面倒F天线缝隙加载等技术带来的两个谐振点频率相差大、带宽较窄的缺点.利用时域有限差分法对天线仿真和优化,天线的两个频段的中心工作频率分别位于我国分配给RFID技术使用的两个超高频频段内.在ISO/IEC推荐RFID使用频段内的反射损失小于-10dB,天线的相对带宽达到17%以上.优化3dB电桥馈电网络设计,在工作频段内为天线提供等功率、相位差为90°的激励信号,天线具有圆极化特性.仿真和测试结果表明:优化天线设计很好地缓解了天线带宽增加和天线效率下降的矛盾,在我国为RFID分配的频段内具有高的天线效率,并能够工作在ISO/IEC推荐使用的频段内,达到实用化要求.     

Capacity analysis of high-rank line-of-sight MIMO channels

Matrix perturbation theory is utilized to investigate high-rank line of sight multiple input multiple output channels in a microwave relay system. The upper and lower bounds of channel capacity are derived based on space time block codes technique and singular values decomposition. A useful constraint for designing LOS MIMO channels is developed by the use of the condition number of the MIMO channel matrix. The theoretical analysis of channel capacity is confirmed by the simulation. The results show that the proposed method is able to give a physical explanation of the high-rank LOS MIMO channel matrix characteristics.     

Codebook design for uplink of densely small cells

The shrinking of cell-size brings significant changes to the wireless uplink of densely small cells （DSCs）. A codebook design is proposed that utilizes the strong line of sight （LOS） chan- nel component existing in a DSC system for uplink of the DSC system. To further improve the uplink performance, the high-rank codebook is designed based on singular value decomposition （SVD） due to the unnecessary preservation of strict constant modulus in the DSC system. And according to the simulation result, the proposed codebook leads to significant sum-rate gain and appreciable block error rate （BLER） performance improvement in the DSC system.     

Single foggy image restoration based on spatial correlation analysis of dark channel prior

Focusing on the degradation of foggy images, a restora- tion approach from a single image based on spatial correlation of dark channel prior is proposed. Firstly, the transmission of each pixel is estimated by the spatial correlation of dark channel prior. Secondly, a degradation model is utilized to restore the foggy image. Thirdly, the final recovered image, with enhanced contrast, is obtained by performing a post-processing technique based on just-noticeable difference. Experimental results demonstrate that the information of a foggy image can be recovered perfectly by the proposed method, even in the case of the abrupt depth changing scene.     

阵列天线通道不一致性校正的辅加阵元法

MUSIC算法是一种基于特征值分解的超分辨DOA估计算法,在理想阵列条件下,其估计性能良好,但当信号模型与实际信号环境不匹配,即存在系统误差时,MUSIC算法的估计性能会严重下降,甚至失效。针对模型中普遍存在的通道不一致性误差,本文首先分析了此类误差对测向性能的影响,并提出了一种通道误差校正的简易算法,该方法通过对来自辅加阵元信号的数据信息进行处理,获取通道不一致性误差的估计,通过误差补偿有效地抑制了通道不一致性的影响,提高了DOA估计的性能。给出了应用该方法的具体步骤,计算机仿真结果证明了该算法的有效性。     

质子交换膜燃料电池混合建模研究

支撑向量机（SVM）理论完备,泛化能力强,很适合对燃料电池建模。但是建立高维SVM模型需要大量的实验数据,为了克服这一困难,使用SVM和压力增量机理模型相结合的方法对质子交换膜燃料电池进行混合建模：SVM模型只考虑电流和温度对电压的影响,而压力增量模型则在此基础上预测阴极压力和阳极压力对电压的影响。混合后的模型能够预测不同电流、温度、阴极压力和阳极压力下的输出电压。结果表明这种方法建立的数学模型误差小于1.6%,能够达到很好的拟合精度。