随机参差重频法抗雷达导引头距离波门前拖研究

文章分析了DRFM距离拖引干扰的工作原理,建立了干扰的信号模型。根据自动增益控制(AGC)变化对干扰进行了检测,在此基础上利用随机参差重频的方法对距离波门前拖进行抑制,在不同的干信比下分别进行了外场试验验证,通过对试验结果的分析表明了该方法能够有效的抑制干扰。     

西安市过渡季节办公建筑室内热环境研究

根据在过渡季节里对所选取的办公建筑进行现场测试所得的数据,并通过分析调查问卷内容得出:西安地区过渡季节气候相对比较舒适。这个季节室内主观热感觉中性温度与当PMV=0时的室内温度值较接近,分别为25.6℃、25.24℃。     

Gas Sensing of NiO‐SCCNT Core–Shell Heterostructures: Optimization by Radial Modulation of the Hole‐Accumulation Layer

Hierarchical core–shell (C–S) heterostructures composed of a NiO shell deposited onto stacked‐cup carbon nanotubes (SCCNTs) are synthesized by atomic layer deposition (ALD). A film of NiO particles (0.80–21.8 nm in thickness) is uniformly deposited onto the inner and outer walls of the SCCNTs. The electrical resistance of the samples is found to increase of many orders of magnitude with the increasing of the NiO thickness. The response of NiO–SCCNT sensors toward low concentrations of acetone and ethanol at 200 °C is studied. The sensing mechanism is based on the modulation of the hole‐accumulation region in the NiO shell layer upon chemisorption of the reducing gas molecules. The electrical conduction mechanism is further studied by the incorporation of an Al₂O₃ dielectric layer at NiO and SCCNT interfaces. The investigations on NiO–Al₂O₃–SCCNT, Al₂O₃–SCCNT, and NiO–SCCNT coaxial heterostructures reveal that the sensing mechanism is strictly related to the NiO shell layer. The remarkable performance of the NiO–SCCNT sensors toward acetone and ethanol benefits from the conformal coating by ALD, large surface area of the SCCNTs, and the optimized p‐NiO shell layer thickness followed by the radial modulation of the space‐charge region.     

Oriented Crystallization of Mixed‐Cation Tin Halides for Highly Efficient and Stable Lead‐Free Perovskite Solar Cells

As the most promising lead‐free branch, tin halide perovskites suffer from the severe oxidation from Sn²⁺ to Sn⁴⁺, which results in the unsatisfactory conversion efficiency far from what they deserve. In this work, by facile incorporation of methylammonium bromide in composition engineering, formamidinium and methylammonium mixed cations tin halide perovskite films with ultrahighly oriented crystallization are synthesized with the preferential facet of (001), and that oxidation is suppressed with obviously declined trap density. MA⁺ ions are responsible for that impressive orientation while Br^‐ ions account for their bandgap modulation. Depending on high quality of the optimal MA_0.25FA_0.75SnI_2.75Br_0.25 perovskite films, their device conversion efficiency surges to 9.31% in contrast to 5.02% of the control formamidinium tin triiodide perovskite (FASnI₃) device, along with almost eliminated hysteresis. That also results in the outstanding device stability, maintaining above 80% of the initial efficiency after 300 h of light soaking while the control FASnI₃ device fails within 120 h. This paper definitely paves a facile and effective way to develop high‐efficiency tin halide perovskites solar cells, optoelectronic devices, and beyond.     

Revisiting the Worksite in Worksite Health Campaigns: Evidence From a Multisite Organ Donation Campaign

This article advances the beginnings of a general theory of organizational features to aid in understanding why health campaigns that work well in one organization may be ineffectual in another organization. The physical, social, and information structures of organizations are theorized to create an interaction environment that is distinct to each organization and that influences health campaigns. To test this argument, an organ donation campaign was conducted in 46 organizations. Multilevel modeling yielded mixed findings. Physical structure was negatively associated with signing an organ donor card. Social structure and information structure were positively associated with communication with coworkers about donation and communicative peer influence. Industry type was positively associated with knowledge change.     

大曲面检测技术研究

大曲面的检测对于三坐标测量机是一个难题,以电子经纬仪作为传感器的工业测量是一种新的方法,可以解决这个难题.这种测量属于非接触测量,因此被测工件的状态是不受约束的.另外一个优点是它可以在较大的测量范围内达到较高的测量精度.在本文中,检测了处于架设状态下的大曲面,同时研究了相关的检测技术.由于直接得到的测量结果是采样点的三维坐标,所以首先需要分析其坐标与被检测量之间的关系,根据曲面的特征,其坐标偏差的标准偏差值作为评价型面质量的参数;然后建立相应的检测系统.在建立的过程中,需要考虑检测精度和曲面与经纬仪的位置关系.检测结果表明,这些技术可以实现对大曲面的高精度检测,并且具有广泛的应用前景.     

Location and calculation-free node-scheduling schemes in large wireless sensor networks

In wireless sensor networks that consist of a large number of low-power, short-lived, unreliable sensors, one of the main design challenges is to obtain long system lifetime without sacrificing system original performance (sensing coverage and sensing reliability). To solve this problem, one of the potential approaches is to identify redundant nodes at the sensing interface and then assign them an off-duty operation mode that has lower energy consumption than the normal on-duty mode. In our previous work [J. Wireless Commun. Mobile Comput. 3 (2003) 271; Processing of ACM Wireless Sensor Network and Application Workshop 2002, September 2002], we proposed a node-scheduling scheme, which can provide a 100% sensing coverage preservation capability. This, however, requires each node to be aware of its own and its neighbors’ location information. Also, in that scheme, each node has to do accurate geometrical calculation to determine whether to take an off-duty status. In this paper, we propose and study several alternative node-scheduling schemes, which cannot completely preserve the original system coverage, but are nonetheless light-weighted and flexible compared with the previous one. Our simulation results compare these schemes with the previous one and demonstrate their effectiveness.     

Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.     

集成成像立体显示技术研究进展

集成成像立体显示是一种水平和垂直方向同时具有运动视差的真三维立体显示技术。本文概述了集成成像立体显示在显示三维图像时存在的景深范围小,视角范围窄,赝像等问题,介绍了提升景深范围、扩大视角、消除赝像的技术方法。介绍了利用子图像阵列进行计算机三维虚拟重建的最新研究进展。通过研究指出,具有二维和三维显示模式转换功能的集成成像立体显示技术是超薄型真三维立体显示器的重要发展方向。