高温N2气氛下树脂结合刚玉材料中阿隆相的形成机制

以酚醛树脂为结合剂,分别以100wt%烧结刚玉细粉、100wt%电熔刚玉细粉和50wt%烧结刚玉加50wt%电熔刚玉混合细粉为原料制备试样,试样在N₂气氛下经1 500℃和1 600℃烧成,对烧后试样进行XRD、SEM和EDAS表征分析。结果表明：1 500℃烧后试样中生成了γ-AlON（Al₅O₆N）和12H多型体（Al₆O₃N₄）,1 600℃烧后试样中生成了γ-AlON（Al₅O₆N）、21R多型体（Al₇O₃N₅）和16H多型体（Al₈O₃N₆）。1 600℃烧成试样中生成的阿隆（AlON）含量较1 500℃烧成试样显著增多。在相同温度下,50wt%烧结刚玉加50wt%电熔刚玉混合细粉试样中生成的AlON含量最多,100wt%电熔刚玉细粉试样次之,100%烧结刚玉细粉试样中生成的AlON含量最少。分析了AlON的形成机制并建立了刚玉细粉与碳的反应模型。     

Threshold Filtering Semi-Supervised Learning Method for SAR Target Recognition

The semi-supervised deep learning technology driven by a small part of labeled data and a large amount of unlabeled data has achieved excellent performance in the field of image processing. However, the existing semi-supervised learning techniques are all carried out under the assumption that the labeled data and the unlabeled data are in the same distribution, and its performance is mainly due to the two being in the same distribution state. When there is out-of-class data in unlabeled data, its performance will be affected. In practical applications, it is difficult to ensure that unlabeled data does not contain out-of-category data, especially in the field of Synthetic Aperture Radar (SAR) image recognition. In order to solve the problem that the unlabeled data contains out-of-class data which affects the performance of the model, this paper proposes a semi-supervised learning method of threshold filtering. In the training process, through the two selections of data by the model, unlabeled data outside the category is filtered out to optimize the performance of the model. Experiments were conducted on the Moving and Stationary Target Acquisition and Recognition (MSTAR) dataset, and compared with existing several state-of-the-art semi-supervised classification approaches, the superiority of our method was confirmed, especially when the unlabeled data contained a large amount of out-of-category data.     

Joint range and angle estimation for an integrated system combining MIMO radar with OFDM communication

Multidimensional Systems and Signal Processing - To perform the integration of radar and communication in waveform, we design an integrated system combining multiple-input multiple-output radar...     

垂直型MoS2/C60范德华异质结的研究

研究了采用垂直堆垛方式构筑的MoS2/C60范德华异质结的特性。利用直流磁控溅射法制备Mo薄膜,对Mo薄膜进行硫化退火处理得到MoS2薄膜,采用真空蒸镀法在MoS2薄膜上沉积C60进而形成MoS2/C60范德华异质结,并制备了Au/MoS2/C60/Al结构的器件。对MoS2薄膜的晶体结构进行了分析,对MoS2,C60及MoS2/C60薄膜的喇曼光谱及光吸收特性进行了测试和表征。结果表明:经过750℃退火后的MoS2晶型为2H型;由于在MoS2和C60薄膜之间范德华力的存在,相对于生长在Si/SiO2衬底上,沉积在MoS2上的C60薄膜喇曼特征峰发生红移;MoS2/C60薄膜在可见光范围内具有明显的光吸收特性;异质结表现出良好的整流特性,通过电子导电模型分析得出电子的传输机制包含热电子发射,空间电荷限制电流传导(SCLC)和隧穿现象。     

聚丙烯轿车专用料的光老化和光稳定

介绍了用于轿车保险杠的ＰＰ／ＰＥ／ＥＰＤＭ共混物的氙灯人工加速老化及户外暴露实验结果，分析了不同抗老化体系对ＰＰ／ＰＥ／ＥＰＤＭ共混物光老化后拉伸性能、冲击性能及外观变化的影响。     

Effect of in situ synthesized macroactivator on morphology of PA6/PS blends via successive polymerization

In situ polymerization and in situ compatibilization was adopted for preparation of ternary PA6/PS‐g‐PA6/PS blends by means of successive polymerization of styrene, with TMI and ε‐caprolactam, via free radical copolymerization and anionic ring‐opening polymerization, respectively. Copolymer poly(St‐g‐TMI), the chain of which bears isocyanate (? NCO), acts as a macroactivator to initiate PA6 chain growth from the PS chain and graft copolymer of PS‐g‐PA6 and pure PA6 form, simultaneously. The effect of the macroactivator poly(St‐g‐TMI) on the phase morphology was investigated in detail, using scanning electron microscopy. In case of blends with higher content of PS‐g‐PA6 copolymer, copolymer nanoparticles coexisting with the PS formed the matrix, in which PA6 microspheres were dispersed evenly as minor phase. The content of the compositions (homopolystyrene, homopolyamide 6, and PS‐g‐PA6) of the blends were determined by selective solvent extraction technique. The mechanical properties of PA6/PS‐g‐PA6/PS blends were better than that of PA6/PS blends. Especially for the blends T10 with lower PS‐g‐PA6 copolymer content, both the flexural strength and flexural modulus showed significantly improving because of the improved interfacial adhesion between PS and PA6. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

稳健的InSAR动目标检测与测速方法

针对干涉合成孔径雷达(InSAR)构型下动目标检测与测速中存在相位耦合以及地形起伏引起的杂波非平稳问题,提出一种动目标检测方法.首先利用两幅SAR图像的相关性进行图像配准,然后进行去平地相位及高程相位补偿,采用噪声子空间投影法,有效地抑制了起伏杂波,实现了InSAR构型中运动目标的检测,进一步提高了动目标检测性能和测速精度.理论分析和实测数据结果证明了该方法的有效性和实用性.     

摄影机同步控制系统的研究

对160经纬仪摄影机同步控制系统作了全面的分析,提出了几种可行的控制方案,并进行了讨论和比较分析。着重对一种直流电机作为执行机构,8098作为中央处理单元的控制方案作了实验。起动过程引入电流检测反馈,使电机实现大电流快速起动,接近给定转速后电流环开环,引入转速、位置负反馈,缩短了同步时间,完成了同步控制系统性能的改善。     

Optical performances of mono‐dispersed spherical YAG:Ce3+ nano‐phosphor achieved by one‐pot synthesis

Mono‐dispersed spherical YAG:Ce³⁺ nano‐phosphors were successfully synthesized by a one‐pot glycol‐thermal process using aluminum isopropoxide, yttrium, and cerium acetate hydrates as the precursor, (1,4)‐butanediol as the solvent, ethidenediamine as the additive agent that can both control the morphology and improve the optical performances of the as‐achieved products. The as‐prepared YAG:Ce³⁺ nano‐phosphors displayed mono‐dispersed spheres of about 150 nm and an improved optical performance with a quantum yield (QY) of 41% and good photostability, indicating that they have a considerable potential to be applied in solid‐state lighting or used as coatings in other optical electronic devices.     

Sum and difference coarray based MIMO radar array optimization with its application for DOA estimation

Based on the sum and difference coarrays, multiple-input multiple-output (MIMO) radar with minimum redundancy (MR) concept, referred to as MR MIMO, can considerably increase the spatial degrees of freedom (DOFs). However, traditional MR MIMO needs computational search to determine the position of each element. In this paper, a modified MR monostatic MIMO configuration is proposed, referred to as MMRM MIMO. In the proposed system, the MMRM MIMO radar is consisted of several levels of uniform linear array, which brings the advantage that the position of each element can be determined without computational search. Furthermore, it offers more than \(N^{2}\) DOFs for an N-elemental array. In order to utilize the extended DOFs of MMRM MIMO radar for direction-of-arrival (DOA) estimation, an average Toeplitz approximation method (TAM) is employed, which achieves robust performance even under low signal-to-noise ratio, few snapshots and array error. Numerous simulation results are provided to demonstrate the effectiveness of the proposed method for DOA estimation.