热丝法氢处理多晶硅锗薄膜

优化了热丝法氢处理多晶硅锗薄膜工艺条件.通过测试材料暗电导的温度特性得出多晶硅锗材料的电导激活能,从而考察氢处理效果.结果表明,采用此技术可有效减少多晶硅锗薄膜中的缺陷态.在优化氢处理时衬底和热丝的温度后,可以把处理时间缩短致30min之内,明显短于其他氢处理技术.     

Ultrawide-band synthetic aperture radar for detection of unexplodedordnance: modeling and measurements

Electromagnetic (EM) scattering from subsurface unexploded ordnance (UXO) is investigated both theoretically and experimentally. Three EM models are considered: the multilevel fast multipole algorithm (MLFMA), the method of moments (MoM), and physical optics (PO). The relative accuracy of these models is compared for several scattering scenarios. Moreover, the model results are compared to data measured by an experimental synthetic aperture radar (SAR) system, SAR images have been generated for subsurface UXO targets, in particular 155-mm shells. We compare SAR images from the measured data with theoretical images produced by the MoM and PO simulations, using a standard back-projection imaging technique. In addition to such comparisons with measurement, we consider additional buried-UXO scattering scenarios to better understand the underlying wave phenomenology     

大功率全固态广播发射机的综合防雷措施

文中对雷电的种类、分布规律及其入侵途径进行了介绍,说明了广播发送设备的雷电防护原理,结合实际工作情况详细阐述了大功率全固态广播发射机的防雷措施,说明了防霉维护检查应注意的事项。     

Modeling the Effect of Human Body on TOA Based Indoor Human Tracking

In time-of-arrival (TOA) based indoor human tracking system, the human body mounted with the target sensor can cause non-line of sight (NLOS) scenario and result in significant ranging error. However, the previous studies on the behavior of indoor TOA ranging did not take the effects of human body into account. In this paper, measurement of TOA ranging error has been conducted in a typical indoor environment and sources of inaccuracy in TOA-based indoor localization have been analyzed. To quantitatively describe the TOA ranging error caused by human body, we introduce a statistical TOA ranging error model for body mounted sensors based on the measurement results. This model separates the ranging error into multipath error and NLOS error caused by the creeping wave phenomenon. Both multipath error and NLOS error are modeled as a Gaussian variable. The distribution of multipath error is only relative to the bandwidth of the system while the distribution of NLOS error is relative to the angle between human facing direction and the direction of transmitter–receiver, signal to noise ratio and bandwidth of the system, which clearly shows the effects of human body on TOA ranging.     

An improved look-up table predistortion technique for HPA with memory effects in OFDM systems

It is well known that HPAs (High Power Amplifiers) are inherently nonlinear devices and many researches have focused on the predistortion for memoryless HPAs. However, memory effects of HPAs can no longer be ignored when communication systems have wider bandwidth. Memoryless predistortion techniques proposed previously seldom have satisfactory effectiveness for typical wideband applications such as OFDM (Orthogonal Frequency Division Multiplexing) systems. In this paper, an improved adaptive predistortion method called 2D LUT (2-dimension look-up table) with different accuracy levels is presented to linearize HPAs with memory effects. Simulation and experimental results show that 2D LUT implements excellent performance in mitigating the signal deterioration caused by memory effects, both rectifies the signal constellation distortion and suppresses the spectrum emission. Large scale matrix computation is also avoidable in these adaptive algorithms, which makes them feasible when a real-time system is necessary.     

MOEMS光学系统的发展与应用

概述了MOEMS光学系统的种类和特点,介绍了几种主要的MOEMS光学产品、机理和应用方向,阐明了其作为光电技术的前沿所具有的重要作用和广阔前景,提出了相关的研究建议。     

Si（111）-(3×3)R30°-Ga表面原子结构

利用自动张量低能电子衍射(ATLEED)定量地研究Si（111）-（3×3）R30°-Ga重构表面的原子结构．证实了Ga原子吸附在T4位即第二层Si原子所对的空位上,同时给出了表面最顶层7个原子层的详细坐标．可靠性因子RVHT＝0.143表明理论计算和实验符合得非常好．     

Room‐Temperature Tailoring of Vertical ZnO Nanoarchitecture Morphology for Efficient Hybrid Polymer Solar Cells

A ZnO nanoarchitecture, i.e., ZnO nanosheet (NS) framework, is demonstrated to be a promising electron acceptor and direct electron transport matrix for polymer‐inorganic hybrid solar cells. The ZnO NS framework is constructed on nanoneedles/indium tin oxide substrate via a room‐temperature chemical bath deposition (RT CBD). The framework morphology can be simply tailored by varying the concentration of precursor solution in the RT CBD. The ZnO nanoarchitecture with an appropriate free space between the NSs is consequently demonstrated to facilitate poly(3‐hexylthiophene) (P3HT) infiltration, resulting in superior interface properties, i.e., more efficient charge separation and less charge recombination, in the hybrid. Moreover, apart from the characteristics similar to the ZnO nanorod (NR) array, including vertical feature and single crystalline structure, the ZnO NS framework exhibits a slightly larger absorption edge and a faster electron transport rate. A notable efficiency of 0.88% is therefore attained in the ZnO NS‐P3HT hybrid solar cell, which is higher than that of the ZnO NR‐P3HT hybrid solar cell.     

Superior Low-Temperature Reversible Adhesion Based on Bio-Inspired Microfibrillar Adhesives Fabricated by Phenyl Containing Polydimethylsiloxane Elastomers

Gecko-inspired microfibrillar adhesives have achieved great progress in microstructure design and adhesion improvement over the past two decades. Space applications nowadays show great interest in this material for the characteristics of reversible adhesion and universal van der Waals interactions. However, the impact of harsh environment of space on the performance of microfibrillar adhesives, especially the extreme low temperature, is rarely addressed. Herein, microfibrillar adhesives fabricated by phenyl containing polydimethylsiloxane (p-PDMS) elastomers with superior low-temperature reversible adhesion is proposed. p-PDMS elastomers are synthesized through one-pot anionic ring-opening copolymerization, and the resulting elastomers become non-crystallizable with excellent low-temperature elasticity. Low-temperature adhesion tests demonstrate that the adhesion strength of microfibrillar adhesives fabricated by p-PDMS elastomers can be well maintained to as low as −120 °C. In contrast, the adhesion strength of pure PDMS microfibrillar adhesive reduces more than 50% below its crystallization temperature. The low-temperature cyclic adhesion tests further demonstrate that p-PDMS microfibrillar adhesives exhibit superior reversible adhesion compared to that of PDMS microfibrillar adhesives, owing to the sustainable conformal contact and even distribution of loads over repeated cycles. This study provides a new fabrication strategy for microfibrillar adhesives, and is beneficial for the practical application of microfibrillar adhesives.     

基于风云系列静止卫星的信息传输研究

在阐述卫星通信对海军完成远海行动具有重要意义的基础上,通过对风云二号、四号等系列气象静止卫星及其信息传输结构、流程与能力的深入研究,提出了基于风云系列静止卫星 UHF 专用转发器众多信道的信息传输设想,并从信息传输设备的适装性、信息传输能力、通信覆盖范围、信息传输安全性、电磁兼容性、可扩展性等6个方面进行了可行性论证,给出了一些比较典型的军事应用场景,以期增强我海军的军事信息传输能力。