脆弱性检测工具研究

在进行风险评估过程中,脆弱性检测由于其检测过程客观、方法多样,已经成为风险评估中必不可少的一个环节.但由于脆弱性检测工具存在各种误报和漏报,大大影响了检测结果的准确性,并进而影响风险评估的有效性.通过对脆弱性检测工具的测试和深入研究,比较了多款典型脆弱性检测工具之间对不同目标系统的检测结果,分析得出了典型脆弱性检测工具之间检测结果的趋势和特点.     

A Receiver in a Millimeter Wave Radiometer for Atmosphere Remote Sensing

A millimeter wave radiometer system with high resolution is described in this paper, which was used for remote sensing of integrated water vapor and integrated liquid water in the troposphere. A novel receiver technique was adopted in the radiometer system to deracinate an impact of the receiver gain shift on its precision and improve its performance. Measured results show that this radiometer system has enough stability in long time measurement and capability to measure atmospheric brightness temperature.     

Geometric Algebra: A Powerful Tool for Representing Power Under Nonsinusoidal Conditions

Geometric algebra is used in this paper for a rigorous mathematical treatment of power in single-phase circuits under nonsinusoidal conditions, as complex algebra for sinusoidal conditions. This framework clearly displays the multidimensional nature of power, which is represented by a multivector. The power multivector with its three attributes (magnitude, direction and sense) provides the means to encode all the necessary information in a single entity. This property, in conjunction with the fact that there is a one-to-one correspondence between the terms of this multivector, the instantaneous and the apparent power equation, distinguishes it as a highly efficient mathematical tool. In this way one can successfully describe power phenomena and handle practical problems (e.g., power factor improvement). Two simple examples show some of these features. In short, the power multivector under nonsinusoidal situations can be perceived as the generalization of the complex power under sinusoidal situations     

Comparison of Ground-Based Millimeter-Wave Observations and Simulations in the Arctic Winter

During the Radiative Heating in Underexplored Bands Campaign (RHUBC), held in February–March 2007, three millimeter-wave radiometers were operated at the Atmospheric Radiation Measurement Program's site in Barrow, Alaska. These radiometers contain several channels located around the strong 183.31-GHz water vapor line, which is crucial for ground-based water-vapor measurements in very dry conditions, typical of the Arctic. Simultaneous radiosonde observations were carried out during conditions with very low integrated-water-vapor (IWV) content ( $≪ 2 hbox{mm}$). Observations from the three instruments are compared, accounting for their different design characteristics. The overall agreement during RHUBC among the three instruments and between instruments and forward model is discussed quantitatively. In general, the instrument cross-validation performed for sets of channel pairs showed agreement within the total expected uncertainty. The consistency between instruments allows the determination of the IWV to within around 2% for these dry conditions. Comparisons between these data sets and forward-model simulations using radiosondes as input show spectral features in the brightness-temperature residuals, indicating some degree of inconsistency between the instruments and the forward model. The most likely cause of forward-model error is systematic errors in the radiosonde humidity profiles.      

The GLOBCARBON Cloud Detection System for the Along-Track Scanning Radiometer (ATSR) Sensor Series

The GLOBCARBON initiative aims to develop a service to generate fully calibrated estimates of at-land products using, in combination, data from the Along-Track Scanning Radiometer (ATSR) sensor series, MERIS and VEGETATION. A fundamental requirement of such processing is the effective removal of extraneous effects introduced by cloud, cloud shadow, snow, and atmosphere in these data. This paper reports on the implementation and extension of a new cloud and snow processing system for land, which is for the ATSR sensor series. The snow processor is as implemented for the Moderate Resolution Imaging Spectrometer, whereas the cloud processor is based on APOLLO, with extensions to generate the probabilities of cloud presence and a further test to eliminate the cloud missed by APOLLO. The system was tested on 48 images representing a wide range of cloud types and forms over three contrasting biomes-boreal forest, desert savannah, and tropical evergreen forest. Excellent results are produced and represent a major improvement over the original flagging system. The approach has been adopted in GLOBCARBON for the processing of 500 000 ATSR scenes and 20 000 AATSR striplines.     

Microwave Radiometer Radio-Frequency Interference Detection Algorithms: A Comparative Study

Two algorithms used in microwave radiometry for radio-frequency interference (RFI) detection and mitigation are the pulse detection algorithm and the kurtosis detection algorithm. The relative performance of the algorithms is compared both analytically and empirically. Their probabilities of false alarm under RFI-free conditions and of detection when RFI is present are examined. The downlink data rate required to implement each algorithm in a spaceborne application is also considered. The kurtosis algorithm is compared to a pulse detection algorithm operating under optimal RFI detection conditions. The performance of both algorithms is also analyzed as a function of varying characteristics of the RFI. The RFI detection probabilities of both algorithms under varying subsampling conditions are compared and validated using data obtained from a field campaign. Implementation details, resource usage, and postprocessing requirements are also addressed for both algorithms.     

An Micro-Bandpasss (6.3≈7.6μm) Filter for the Multichannel Scanning Radiometer

Optical coatings are designed and produced for the multichannel scanning radiometer meteorological space instrument operating in the spectral range 6.3≈7.6μm. First the choice of substrates and layers materials is discussed. Then the substrate temperatures dependent effects of three different Te-enriched PbTe single layers on the dispersion and absorption characteristics and carrier concentration are studied. The experimental results demonstrate that the performance of the coating made using PbTe + 0.3 at. % Te material is better than that of the others. Finally, details of the spectral design and manufacture of such a filter which meets the demanding bandwidth and transparency requirements of the application are presented. This design model is based on the optical and semiconductor properties of a multilayer filter containing PbTe layer materials in combination with the dielectric dispersion of ZnSe deposited on the a Ge substrate. Comparisons between the computed spectral performance of the model and spectral measurements from manufactured coatings over a wavelength range of 6.3≈7.6μm are presented.     

EXAFS as Powerful Analytical Tool for the Investigation of Organic–Inorganic Hybrid Materials

The potential and application of X‐ray absorption spectroscopy (XAS) for structural investigations of organic–inorganic hybrid materials, with a special emphasis on systems consisting of inorganic building blocks (clusters) embedded into polymer backbones, is extensively reviewed. In the first part of the paper, the main features of organic–inorganic hybrid materials, their classification, the synthetic approaches for their preparation, and their applications are concisely presented, whereas the particular issues related to their characterization are discussed in more detail. In the second section of the paper, the principles and the theoretical background of the XAS method, including experimental design, data reduction, evaluation, analysis, and interpretation are described and discussed. Examples of potentialities of the method for the short‐range structural investigation of inorganic nanostructures in hybrids are provided, and the state‐of‐the‐art in the field of hybrid materials is reviewed. In the third part, six different case studies belonging to our past and present experience in this field are presented and discussed, with a particular focus on their XAS investigation.     

噪声相加比较式微波辐射计体制研究

在微波辐射计的应用中,系统增益长期稳定性是一个重要设计指标。本文给出了一种噪声相加比较式微波辐射计体制。通过实验证明此体制具有测量的准确度与系统的增益变化无关、输出与接收机噪声温度无关的优点。     

The Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E), NASDA's contribution to the EOS for global energy and water cycle studies

The Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) was developed and provided to the National Aeronautics and Space Administration's EOS Aqua satellite by the National Space Development Agency of Japan, as one of the indispensable instruments for Aqua's mission. AMSR-E is a modified version of AMSR that was launched December 2002 aboard the Advanced Earth Observing Satellite-II (ADEOS-II). It is a six-frequency dual-polarized total-power passive microwave radiometer that observes water-related geophysical parameters supporting global change science and monitoring efforts. The hardware improvements over existing spaceborne microwave radiometers for Earth imaging include the largest main reflector of its kind and addition of 6.925-GHz channels. These improvements provide finer spatial resolution and the capability to retrieve sea surface temperature and soil moisture information on a global basis. This paper provides an overview of the instrument characteristics, mission objectives, and data products.     

The Dependency Model: A Tool for Calculating System Effectiveness

The Dependency Model (DM) is a mathematically unsophisticated but useful and practical tool for measuring the effectiveness (reliability, availability, maintainability, efficiency, etc.) of a complex system. Contrary to classical models, the DM does not require arbitrarily chosen statistical distributions or expensive simulations for its application. The large computer storage and running time requirements, the need for an accurate random number generator, and the inherent stochastic inaccuracy associated with such Monte Carlo techniques are thereby avoided. However, the DM does require the user to assign relative weights to the elements of the system, and to measure the performance of the lowest level elements considered. Common models such as GEM, TIGER, and REX assume a series-parallel structure. Although this might be sensible when applied to the lowest replaceable units (LRUs) in a hardware structure, it is unreasonable to apply it to components further up in the hierarchy, or to software. Thus, redundancy is not clearly defined for software. If there is an error in the code, placing identical programs in parallel does not eliminate that error. The series-parallel logic structure allows only for each component to be up or down, with no gradation. In contrast, the DM measures the degree of failure of a component or system, in addition to the probability and method of failure that can be determined from classical models. The elementary structure and flexibility of the DM yield additional benefits.     

顺序扫描阵列配置方法研究

对于超宽带稀疏阵列,均匀无冗余阵列具有低栅瓣水平和高方位向分辨率。阵列配置的目的是设计双程阵列,使其单程等效阵列是均匀无冗余的。文中主要配置顺序扫描阵列,证明了若阵元总数大于4,没有均匀无冗余阵列的配置方法。然后给出了一种非均匀阵列配置方法,分析了其方位向分辨率和栅瓣水平。理论与仿真表明,文中提出的方法比与其阵元总数相同的端发多收阵列的栅瓣低。最后,根据所需要的方位向分辨率和栅瓣水平配置了一种实际顺序扫描阵列。     

陆装车载雷达操控车结构设计

介绍某陆军车载雷达操控车的结构设计方案。对雷达操控车结构组成、行驶性能、工作温控、载重分配、电磁屏蔽、人机工程等方面的性能作了详细论述。     

大气相对湿度与雷暴天气的统计关系研究

从理论上分析大气相对湿度与雷达反射率因子的关系,利用2009年济南地区气象站的观测资料,根据天气现象和降雨量计算出雨强,通过Z-I的关系,把降雨强度转换为回波强度,最后统计出在不同的温度下大气相对湿度与雷达反射率因子之间的关系,从而通过检测湿度转化为雷达回波强度,为雷电的预测提供理论依据.     

主动雷达导引头地面雷达站识别技术研究

该文针对主动雷达导引头对地面防空单元制导雷达站的识别问题,在天线电磁散射特性研究的基础上,提出了雷达天线的多特征融合识别算法。首先对相控阵雷达天线的电磁散射特性进行了建模和计算,然后采用多普勒波束锐化技术对目标进行2维成像以提高天线的检测概率并估计目标雷达天线的RCS序列,基于RCS序列的幅度特性与周期特性,构造了相控阵天线的4类特征,并提出了相应的识别算法及融合识别算法。仿真实验表明算法具有较高的识别概率。     

新型显示效果度量工具:空间标准观测仪

在显示器的设计过程中，“美景只出现在旁观者眼中”（意即只有设计者之外的旁观者才能评价图像质量的好坏）。但到目前为止，业界对人眼观测到的画面质量依然缺乏有效的评估手段。这里，我们将要详细介绍一种新型三维空间图像可见度的评估工具：空间标准观测仪（spatial standard observer，SSO）。与亮度、CIE色度的测量相同，SSO为我们提供了另一项对人类观察有意义的测量标准的尺度。     

空气中烧成锌电极浆料的研究

半导瓷用锌电极浆料可在空气中烧成。材料配方的选择和工艺的优化是实验的关键。实验中以硼硅铅玻璃和金属有机化合物作为锌电极浆料的粘结剂和抗氧化剂，取得了良好的效果。     

欧姆接触镍电极的研究

对镍电极浆料进行了实验研究。材料配方的选择和工艺的优化是实验的关键。实验中用玻璃粉和硼粉作为镍电极浆料的粘合剂和抗氧化剂，其中镍粉的质量分数不得低于65％，研制出的镍浆料可在大气中于810℃烧结在PTC等半导瓷上构成电极。通过扫描电镜(sEM)可以发现镍电极能牢固地附着在陶瓷体上并具有良好的欧姆接触性能。     

A Low-Cost Microwave Radiometer for the Detection of Fire in Forest Environments

This paper deals with the development of a microwave noise-adding radiometer, which is purposely designed for the fire detection in forest environments. The sensor operates at 12.65 GHz and exploits commercial Satellite Television (SAT-TV) components such as a parabolic dish and a low-noise block. First, a simple system model is presented to estimate the radiometric contrast due to the presence of fire (increase in the antenna noise temperature with respect to the background) at a certain distance from the receiving antenna. Then, the design of the sensor is addressed, underlining the key technologies that allow the required performance to be attained at low industrial costs. An experimental characterization of the developed radiometer is reported focusing on both accuracy and sensitivity issues. Due to a continuous gain calibration based on the noise-adding procedure, the antenna noise temperature can be retrieved with an absolute error of 4 K without any thermal stabilization of the instrument electronics. Last, real fire detection experiments have been carried out both in laboratory and open-space environments. A radiometric contrast of 8.8 K has been recorded for a wooden fire of 0.2 $hbox{m}^{2}$ placed at a distance of about 30 m from the antenna.