地面移动目标被动探测最优路径规划

提出了一种机载传感器对地面移动目标被动测量的最优路径规划方法。该方法考虑目标状态估计精度,采用扩展卡尔曼滤波算法进行传感器量测信息滤波,进而实时计算传感器目标探测跟踪的信息矩阵。在此基础上,考虑目标被动探测的环境及飞行器性能约束,以目标信息阵等为指标,进行被动探测最优路径规划,实现地面移动目标探测。最后,进行了该被动探测最优路径规划算法的仿真研究。研究结果表明,所提出的被动探测最优路径规划算法能够快速、有效地完成最优被动探测路径的规划计算。     

Washable Multilayer Triboelectric Air Filter for Efficient Particulate Matter PM2.5 Removal

Efficient removal of particulate matter (PM) is the major goal for various air cleaning technologies due to its huge impact on human health. Here, a washable high‐efficiency triboelectric air filter (TAF) that can be used multiple times is presented. The TAF consists of five layers of the polytetrafluoroethylene (PTFE) and nylon fabrics. Compared with traditional electrostatic precipitator, which requires a high‐voltage power supply, the TAF can be charged by simply rubbing the PTFE and nylon fabrics against each other. The electrical properties of the TAF are evaluated through the periodic contacting–separating of the PTFE and nylon fabrics using a linear motor, and an open‐circuit voltage of 190 V is achieved. After charging, the TAF has a removal efficiency of 84.7% for PM_0.5, 96.0% for PM_2.5, which are 3.22 and 1.39 times as large as the uncharged one. Most importantly, after washing several times, the removal efficiency of the TAF maintains almost the same, while the commercial face mask drops to 70% of its original efficiency. Furthermore, the removal efficiency of the PM_2.5 is very stable under high relative humidity. Therefore, the TAF is promising for fabricating a reusable and high‐efficiency face mask.     

Mesoporous Separation Membranes of Polymer‐Coated Copper Hydroxide Nanostrands

Extremely long and thin nanocomposite fibers are prepared by oxidative polymerization of pyrrole (or aniline) around the surfaces of copper hydroxide nanostrands. The individual nanostrands of 2.5 nm are uniformly coated with a polypyrrole layer of 3 to 4 nm, resulting in hybrid core/shell fibers of about 10 nm in diameter and a few micrometers in length, as confirmed by high‐resolution electron microscopy. The as‐prepared nanocomposite fibers are dispersive in water and can be converted into thin free‐standing films by simply filtering a small volume of the aqueous solution using a polycarbonate membrane filter. The films covering the submicrometer pores of the membrane filter have a thickness of a few tens of nanometers, and provide a mechanically stable nanofiber network with abundant pores of a few nanometers. The network is stable in acidic and basic media, and can be used for protein separation under pressures of at least 90 kPa. The permeation rates of cytochrome c, myoglobin, and ferritin were examined by changing the pH around their isoelectric points. It is seen that the nanofibrous free‐standing films on the polycarbonate membrane filter show clear size selectivity for the proteins, retaining extremely high filtration rates for water. We demonstrate herein durable mesoporous separation membranes made of organic–inorganic nanocomposite fibers and their outstanding performance.     

基于最大熵Kalman滤波的机载SINS自标定技术

针对在机载捷联惯导系统(SINS)自标定过程中,量测噪声呈非高斯分布,导致经典Kalman滤波性能降低的问题,该文提出了基于最大熵Kalman滤波(MCKF)的机载SINS自标定技术。该方法采用最大相关熵准则(MCC)替代经典Kalman滤波的最小均方误差准则,有效利用信号的高阶矩信息,并将其应用于机载SINS自标定系统中。仿真结果表明,在非高斯噪声条件下,该方法能够估计出机载SINS待标定参数,且算法的鲁棒性和误差项估计精度均优于经典Kalman滤波,具有一定的工程应用价值。     

Mask stretching for next generation lithography masks

Next generation lithography tools, such as X-ray, ion, or electron beam lithography equipment set different standards for mask fabrication. A thin film membrane is now the carrier of the pattern to be copied on a substrate. Systematic aberrations are inevitable due to heat distortion during exposure and other influences. The possibility of integrating an active correction system in the mask is investigated and the mechanics for the elastic in-plane stretching of the mask are developed. Equations that relate actuator displacements to the displacement of a finite number of measurement points (or precision points) are derived for in-plane actuation of the mask membrane. A large-scale experimental model as well as a finite-element model was used to demonstrate the validity of this method     

基于TCASⅡ和ADS-B的组合监视防撞系统研究

为了有效地保持空中运行航空器的最小安全间隔和增加空域容量,急需发展独立可靠的空空监视和冲突检测与防撞系统.提出一种集合TCASⅡ和ADS-B技术的组合监视防撞系统,它以TCAsⅡ为基础,将ADS-B信息和TCASⅡ信息融合送入TCASⅡ决策单元,提供机栽监视、冲突检测和决策信息;同时以基于当前统计模型的卡尔曼滤波算法为...     

用金刚石薄膜制造X射线掩模版

用金刚石薄膜作为支撑层，金作为吸收体；同时，采用Ｎｉ合金过渡层来解决金刚石与金之间结合力小，热匹配性能差等问题。制作的掩模版具有较好的反差效果。同时，还具有工艺简单，成品率高等特点。     

Study on deflection of X-ray mask membrane in stepper motion

Deflection of the X-ray mask membrane caused by stepper motion, i.e., changing the mask-to-wafer gap and stepping the wafer parallel to the mask, was evaluated. The effects of film tension, mask configuration and velocity of wafer stage movement on the membrane behavior were examined. The deflection caused by parallel stepping in the proximity gap is very sensitive to the parallelism between the mask and the wafer. The membrane deflection of less than 2 μm and the relaxation time of less than 0.2 sec were observed under the condition of a 20 μm gap and within 0.2 μm/20 mm of mask inclination. It was confirmed that the relaxation time is inversely proportional to the tension of the film. It was also found that the mesa-type mask is capable of reducing the relaxation time to about 30 % less than that of a conventional mask, and that the membrane deflection of the mesa-type mask becomes almost half that of the conventional one. The mesa-type mask is thought to effectively reduce the membrane deflection and the relaxation time.     

Fabrication and Characterization of Nanopillars for Silicon-Based Thermoelectrics

Si-based nanopillars of various sizes were fabricated by lateral structuring using anisotropic etching and thermal oxidation. We obtained pillars of diameter <500 nm, about 25 μm in height, with an aspect ratio of more than 50. The distance between pillars was varied from 500 nm to 10 μm. Besides the fabrication and structural characterization of silicon nanopillars, implementation of adequate metrology for measuring single pillars is described. Commercial tungsten probes, self-made gold probes, and piezoresistive silicon cantilever probes were used for measurements of nanopillars in a scanning electron microscope (SEM) equipped with nanomanipulators.     

洁净室气态分子污染物的监测技术

随着微电子工业工序复杂性的增加和产品尺寸的不断缩小,气态分子污染物(AMC)对产品的影响成为洁净室环境控制中重点关注的问题。文章介绍了洁净室中AMC的定义,重点阐述了AMC的监测技术。     

Standing‐Wave‐Assisted Creation of Nanopillar Arrays with Vertically Integrated Nanogaps for SERS‐Active Substrates

An optical method is used to create multi‐dimensional metal structures with three distinct periodicities for surface‐enhanced Raman scattering (SERS). Periodic arrays of nanopillars are formed by phase‐shift interference lithography on sub‐micrometer length scales. With the help of a standing wave, each nanopillar is made to be a disk‐stacking structure consisting of a series of 20‐nm‐thick metal nanogaps; the nanopillars consequently resemble a pagoda. The vertically integrated metal nanogaps of the metal‐deposited pagoda‐like nanopillars enable strong localization of an electromagnetic field and effective enhancement of Raman signals for molecules adsorbed on the metal surface. Moreover, the nanopillars are arranged in a regular lattice, which results in a low spatial variation of the SERS intensity and provides high reproducibility in measurements. Arrays of the nanopillars can be further micropatterned to have a periodicity ranging from tens of micrometers to a millimeter by subsequently employing photo‐lithography. The nanopillar arrays promote the wetting of sample fluids, which enables the selective confinement of fluids on the array regions of the micropatterns without spreading. Consequently, numerous fluid samples can be separately deposited, enabling SERS‐based analysis of multiple samples using a single substrate.     

天津市某医院空气品质调查

对某一新建医院不同室内场合空气中尘、菌及CO2等污染浓度进行了测试，通过对数据的分析，指出加设一级中效过滤器可有效提高室内空气品质。     

Self‐Assembled Monolayer Coatings on Nanostencils for the Reduction of Materials Adhesion

Nanostencils (shadow masks with submicrometer apertures in a thin silicon nitride membrane) are promising tools for the facile one‐step generation of nanopatterns of various materials by physical vapor deposition. Evaporation through a shadow mask is accompanied by gradual clogging of the apertures due to adhesion of evaporated material. In order to reduce this effect, nanostencils were coated with alkyl and perfluoroalkyl self‐assembled monolayers (SAMs). The formation and properties of SAMs on planar silicon nitride substrates were studied by contact angle goniometry, X‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The SAMs are stable under evaporation of gold at various angles. SAM‐coated nanostencils showed considerably less adhesion of gold compared to bare Si_xN_y stencils.     

基于OpenFilters的He-Ne气体辉光压制窄带滤光片

为了解决环形激光器小型化中信号信噪比随腔长减小而下降的问题,设计了一种能压制He-Ne气体放电辉光而不影响激光光强的窄带滤光片。基于OpenFilters软件独有的step自动膜系设计方法,以初始膜层厚度为线索,设计了符合光谱特性实际应用要求的多个非规整膜系结构。考虑膜层数、膜层厚度及应力等因素,选出便于石英晶振监控的窄带滤光片。在45的入射角下,该滤光片对s偏振光在632.8nm处的峰值透射率为99.9%,通带半峰值全宽为5.2nm,截止带平均透射率为1.35%。结果表明,该滤光片可有效压制He-Ne气体的放电辉光,提高小型环形激光器的信噪比。     

Electrically Activated Ultrathin PVDF‐TrFE Air Filter for High‐Efficiency PM1.0 Filtration

Ultrafine particulate matter (PM) in indoor air has become a serious concern for public health. Therefore, there is a growing interest in filters that can be installed on the window frames of ordinary homes to improve the indoor air quality by natural passive ventilation without using expensive forced air circulation systems. Thus, these filters require a high filtering efficiency and high air permeability and visibility, which do not compromise the original functionality of the windows. The filters developed for this purpose to date have demonstrated a high filtering efficiency for PM_2.5 but a relatively low efficiency for PM_1.0. Here, the performance of the ultrathin poly[(vinylidenefluoride‐co‐trifluoroethylene) (PVDF‐TrFE) nanofiber air filter capable of high‐efficiency PM_1.0 filtration is reported. To enhance the PM_1.0 filtering efficiency, the filter is electrically activated by the polarization of dipoles and triboelectrification using the ferroelectric nature and triboelectrically negative property of the PVDF‐TrFE filter layer. The electrically activated PVDF‐TrFE filter demonstrates a PM_1.0 filtering efficiency of over ≈88% after polarization, which is further improved to ≈94% after triboelectrification. In addition, the filter is ultrathin and air‐permeable with 65% light transmittance. The methods introduced in this work can be adopted to develop high performance, highly visible, and air‐permeable filter media.     

Tailoring Nanonets-Engineered Superflexible Nanofibrous Aerogels with Hierarchical Cage-Like Architecture Enables Renewable Antimicrobial Air Filtration

Purification of pathogenic air has become an essential part of infection prevention and control. Most present air filters can hardly achieve excellent air filtration performance and the effective inactivation of the airborne pathogens at the same time. Herein, a bottom-up approach is reported upon to construct cage-like structured superflexible nanofibrous aerogels (CSAs) with renewable antimicrobial properties by combining electrospun silica nanofibers, bacterial cellulose nanofibers, and the hydrophobic Si O Si elastic binder. The following efficient grafting of N-halamine compounds endows the CSAs with biocidal function. The resultant aerogels exhibit intriguing features of high porosity, hydrophobicity, superelasticity, foldability, renewable chlorination ability (>5400 ppm), high filtration performance toward PM0.3 (>99.97%, 189 Pa), and excellent antibacterial and antiviral activity (6 logs reduction within 5 min contact), enabling the aerogels to intercept and inactivate the pathogenic contaminants in air. The successful synthesis of CSAs provides a new possibility to design high-performance air filtration materials for public health protection.     

Micromachined W-band filters

Results are presented for high performance planar W-band filters based on silicon micromachining techniques common in microsensor fabrication. Two types of micromachined planar transmission lines are studied: microshield line and shielded membrane microstrip (SMM) line. In both of these structures, the conducting lines are suspended on thin dielectric membranes. These transmission lines are essentially “floating” in air, possess negligible levels of dielectric loss, and do not suffer from the parasitic effects of radiation and dispersion. A 90 GHz low pass filter and several 95 GHz bandpass filters are tested and display excellent performance which cannot be achieved with traditional substrate supported circuits in CPW or microstrip configurations. A full-wave finite-difference time-domain (FDTD) technique verifies the measured performance of the W-band circuits and provides a basis for comparison between the performances of membrane supported circuits and equivalent substrate supported circuits     

Fabrication of suspended thin film resonator for application of RF bandpass filter

Characteristics of AlN thin film and thin film resonator for RF bandpass filter have been studied. AlN thin films were deposited by RF magnetron sputter system. Deposition parameters such as N₂ contents, Ar and N₂ partial pressures, and the distance between metal target and substrate were found to affect the piezoelectric response. To fabricate the suspended thin film resonator (STFR) using the piezoelectric AlN thin film, the etching of AlN and the surface micromachining process were conducted. The thickness of AlN film and membrane for the STFR are 2 and 15 μm, respectively. This membrane was fabricated by SOI technology. The device with the dimension of 160 × 160 μm² has a resonant frequency of 1.653 GHz, a K_eff² of 2.4%, a bandwidth of 17 MHz, and a quality factor of 91.7. The device with the dimension of 200 × 200 μm² has a resonant frequency of 1.641 GHz, a K_eff² of 1.2%, and a bandwidth of 9 MHz, and a quality factor of 50.2.     

一种稳健的两维两脉冲杂波相消方法

两维两脉冲杂波对消方法,可以有效地杂波迹进行杂波预滤波,进一步提高后续空时自适应算法的动目标检测性能。但在实际中不准确的载机速度和偏航角等雷达系统参数信息,会制约其杂波抑制性能。为了解决这一问题,文中提出了一种稳健的两维两脉冲杂波相消方法,该方法进一步将载机速度和偏航角误差作为先验知识加入到滤波器系数矩阵设计中,提高了TDPC在雷达系统参数存在误差时的稳健性。并分别利用仿真数据和MCARM实测数据进行了验证。实验结果表明,在载机速度和偏航角存在误差的情况下,相比较TDPC,RTDPC能更加有效地对消杂波,改善了后续空时自适应算法的动目标检测性能。     

纳米TiO2光催化机理及其在空气净化中的应用

分析了纳米TiO2光催化降解空气污染物的典型催化机理,介绍了一种克服前人所采用的一维净化面的缺点而采用三维净化面的新型的空气净化装置mop fan.描述mop fan优点的同时指出在今后的理论研究中要解决的问题.