基于Android系统的船用雷达仿真系统研究

现有的船用雷达模拟器大多是基于桌面系统研发。随着移动互联网的迅速发展,基于移动终端的船用雷达仿真系统具有潜在的应用价值。参照JRC-JMA-9100型号雷达,基于Android移动平台设计并实现了一个船用雷达仿真系统APP。采用一种改进的道格拉斯 普克算法对岸线数据抽稀,使用圆周扫描算法对物标进行扫描求交,提高了雷达模拟器岸线回波的绘制效率。采用瑞利分布、正态分布数学模型,利用模型叠加的方式,实现了海杂波、雨雪杂波的仿真。采用分层显示的方式实现了电子方位线、活动距标圈、平行索引线、自动捕获区、偏心显示等雷达刻度系统功能。仿真结果表明,系统在移动终端上运行稳定,仿真效果良好。     

基于POMDP的主动雷达制导弹干扰措施优化方法

以主动雷达弹对抗为背景,研究了单平台机载电子对抗资源的调度问题。为解决导弹导引头状态观测不确定性问题,引入部分可观测马尔科夫决策过程(POMDP)理论,分析了POMDP模型的要素,建立了针对主动雷达制导导弹的干扰资源优化POMDP模型,并利用最优策略可达空间的连续近似法(SARSOP)进行求解。将电子支援措施(ESM)的观测值输出与电子干扰措施(ECM)的优化策略相结合,提出了一种基于POMDP的电子对抗资源实时调度优化算法。仿真结果表明,该方法能够实现目标状态不确定情况下的干扰资源有效调度,相比现有的调度策略,可以使导引头更多维持在搜索状态,更少停留在稳定跟踪状态。     

基于数据链的预警机协同协作战下的发现目标能力的效能评估

为研究加装数据链后,预警机协同作战情况下的敌我双方实力对比和战斗进程,在对数法的基础上,给出了预警机协同情况下的作战效能评估方法。通过计算有无预警机协同情况下的雷达探测范围,给出了发现目标能力参数变化量的具体表达式。基于Lanchester方程,建立了预警机协同情况下的空战模型,并在5种给定的实力对比条件下,对空战进程进行了仿真,给出了仿真数据及耗损图。结果表明:加装数据链后预警机协同作战的情况下,红方实力只需要大于蓝方实力的77.3%即可获得胜利。     

基于模糊逻辑法的粒子识别研究

毫米波雷达相比于微波雷达对云的探测具有更高的敏感性,本文利用Chilbolton观测场的94GHz毫米波云雷达的基本探测量,结合探空仪的温度廓线数据,根据Shupe总结得到的云粒子相态识别的阈值,采用模糊逻辑算法对一次实际探测进行了反演研究.该模糊逻辑算法采用的主要隶属函数为不对称的梯形函数,识别粒子的相态类别主要分成雨、毛毛雨、液态水、混合相态、冰、雪等6种,对比经典的阈值算法反演的过冷水区域结果后认为,本文所研究的模糊逻辑算法对云中水凝物粒子的相态识别分类基本合理,其反演的结果对于人工影响天气作业以及飞机安全飞行等方面具有重要的意义.     

A PARAFAC estimator for MIMO radar under direction-dependent mutual coupling

Among the various research branches in multiple-input multiple-output (MIMO) radar, Direction finding is an interesting topic and has attracted extensive concerns. However, many previous strategies are only effective to deal with scenarios without model error, such as well-calibrated sensor array, which is unrealistic in practice. This paper revisits the direction finding issue in a bistatic MIMO radar, in which the direction-dependent mutual coupling (MC) effect in both the transmitting array and the receiving array are considered. An estimator based on parallel factor (PARAFAC) decomposition is introduced. Benefit from the fact that the multidimensional structure of the tensor measurement can be explored, the proposed PARAFAC estimator can offer closed-form solution to direction finding without additional pairing calculation, so it is much more accurate and efficient than the state-of-the-art spectrum search method and the rotational invariance algorithm. The improved PARAFAC approach is mathematically analyzed in detail, Several computer trials are carried out to show the theoretical advantages.     

The effect of illumination on the depth profile of thermally annealed MEH‐PPV/dPS blends

Due to its simplicity and cost‐effectiveness, single solution casting of organic optoelectronics has grown in popularity for device fabrication to produce technologies such as organic photovoltaics and thin film transistors. In order to explore the structural evolution that occurs in the film formation of a blend composed of polystyrene and the benchmark conjugated polymer MEH‐PPV, we have performed a series of neutron reflectivity experiments focused on studying the film structure as it changes through the thermal annealing process both in the presence and absence of white light. Results indicate the formation of a nonhomogeneous blend upon casting, which becomes stratified with thermal annealing. More importantly, the extent of stratification varies with illumination, where exposure to white light increases stratification. This data suggests in situ illumination is a potential novel tool to manipulate device‐relevant morphologies of optoelectronic active layers throughout the fabrication process, offering a cheap nondestructive tool to effectively tune desired structural parameters. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1142–1149     

DWMT系统中滤波器组的新设计

研究了ＤＷＭＴ系统中的综合／分析滤波器组．基于系统对运算复杂度和子信道间频谱隔离特性的要求，我们采用了ＥＬＴ快速算法，并在滤波器优化设计过程中，用最大误差最小化准则替代了原ＥＬＴ算法中的最小均方误差准则     

Interface development in polycarbonate/poly(methyl methacrylate) bilayer films

We report the effect of annealing over a range of temperatures and times on the mixing, stability, and interfacial width in thin bilayer films of bisphenol A–polycarbonate (PC) on deuterated poly(methyl methacrylate) (dPMMA). These bilayer films were highly stable when annealed at temperatures of up to 438 K, the temperature at which the degradation of the blends of these materials was first detectable by thermogravimetric analysis. At higher temperatures, dewetting of the PC upper layer of the film occurred at an increasing rate. Nuclear reaction analysis showed that the PC and dPMMA layers remained segregated. Neutron reflectometry data showed that the interfacial width between the two polymer layers grew rapidly from 0.5 nm for an unannealed sample to approximately 4.0 nm, the latter value being in good agreement with the predicted value for the interfacial width in the absence of any reaction. Extended annealing at 438 K and lower temperatures had no effect on the interfacial width, whereas at higher temperatures, the interfacial width increased to approximately 5.5 nm before the films became unstable. The broadening of the interface found at higher annealing temperatures was attributed to an increase in the miscibility of the polymers induced by the monomer from the unzipping of the dPMMA chains. There was no evidence of a thermally induced chemical reaction between the two polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2351–2362, 2001     

Characterization of thin polymer‐like films formed by plasma polymerization of methylmethacrylate: A neutron reflectivity study

The microstructure of the plasma‐polymerized methylmethacrylate (ppMMA) films is characterized using neutron reflectivity (NR) as a function of the plasma reaction time or film thickness. Variation in the crosslink density normal to the substrate surface is examined by swelling the film with a solvent, d‐nitrobenzene (dNB). In the presence of dNB, uniform swelling is observed throughout the bulk as well as at the air surface, and silicon oxide interfaces. The results indicate that the MMA film prepared by plasma polymerization (ppMMA) has a uniform crosslink density from air surface to substrate surface. Additionally, the scattering length density of the plasma‐polymerized MMA film (SLD ≈ 0.750 × 10⁻⁶ Å⁻²) is much lower than that of a conventional PMMA film (SLD = 1.177 × 10⁻⁶ Å⁻²). The increase in film thickness following dNB sorption is 7.5% and at least 36% for the ppMMA and PMMA films, respectively. This suggests that the films formed by plasma polymerization are different from conventional polymers in chemical structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2522–2530, 2004     

Iron sulphide formation in the ferric stearate Langmuir-Blodgett films

Ferric stearate (FeSt) Langmuir-Blodgett (LB) films have been reacted chemically with H₂S gas for making iron sulphide within the organic matrix. Films, before and after the reaction with H₂S, have been analyzed with the X-ray reflectivity (XRR), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) studies. After sulphidation, more ‘pinhole’ defects form which changes the film morphology and the number of layers increases due to the rearrangement of the molecules. Formation of less ordered iron sulphide within the stearic acid multilayers after sulphidation increases the interfacial roughness that decreases the reflectivity. XPS analysis shows that polysulphide forms within the microenvironment of the FeSt LB films after reaction with H₂S whereas both mono and polysulphide are produced when the reaction occurs with FeSt in bulk.