一种8毫米波变张角,半径突变多模圆锥馈源

我们研制了一种8毫米波变张角、半径突变的多模圆锥馈源。计算出其模比并推导出其辐射方向图公式;给出其在两个主平面——E平面与H平面上的辐射方向图和波束场分布特性的测试结果以及电压驻波比VSWR的测量结果;同时给出频带和旁瓣特性。分析与测试共同表明,在34.5GHz～37GHz频带里,该多模馈源的辐射图在大于24dB范围内获得幅度等化且不出现旁瓣,因此具有一定的应用价值。     

Pore‐free mold‐pattern‐transfer method for barrier ribs of HD PDPs

Abstract— Among various barrier‐rib manufacturing processes, the mold‐pattern‐transfer method has potential to reduce processing cost as well as the manufacture of high‐resolution pixels. In this study, the effects of major processing variables of the mold‐pattern‐transfer process on the formation of air‐trapped pores within barrier ribs were examined. The results indicated that with an optimum combination of the processing variables, barrier ribs without trapped defects can be produced, demonstrating the possibility of reducing the number of processing steps and costs of barrier ribs.     

Target differentiation with simple infrared sensors using statistical pattern recognition techniques

This study compares the performances of various statistical pattern recognition techniques for the differentiation of commonly encountered features in indoor environments, possibly with different surface properties, using simple infrared (IR) sensors. The intensity measurements obtained from such sensors are highly dependent on the location, geometry, and surface properties of the reflecting feature in a way that cannot be represented by a simple analytical relationship, therefore complicating the differentiation process. We construct feature vectors based on the parameters of angular IR intensity scans from different targets to determine their geometry and/or surface type. Mixture of normals classifier with three components correctly differentiates three types of geometries with different surface properties, resulting in the best performance (100%) in geometry differentiation. Parametric differentiation correctly identifies six different surface types of the same planar geometry, resulting in the best surface differentiation rate (100%). However, this rate is not maintained with the inclusion of more surfaces. The results indicate that the geometrical properties of the targets are more distinctive than their surface properties, and surface recognition is the limiting factor in differentiation. The results demonstrate that simple IR sensors, when coupled with appropriate processing and recognition techniques, can be used to extract substantially more information than such devices are commonly employed for.     

State observability and condition observability for a class of interacting discrete event systems

This paper introduces the concepts of state observability and condition observability for condition systems, a class of systems composed of discrete state components which interact via discrete binary signals called conditions. Given a set of externally observed conditions, state observability implies that the state of the system can be determined from the observations, and condition observability implies that all unobserved input and output conditions of the system can be determined from the observations. In this paper, we present a class of systems which is state observable and condition observable. We present a method to synthesize an observer system to provide state and condition signal estimates for a single component subsystem.     

程控交换机收号系统模拟的研究

本文提出了一种模拟程控交换机收号系统的有效方法,采用消息驱动收号事件表的思想,运用并发控制技术,实现了在没有话路硬设备的条件下多用户同时拨号在线模拟收号控制的功能。本文提出的收号系统模拟方案已成功应用于某国产中大容量程控交换机的呼叫模拟系统中。     

Intercardinal面上最大副瓣电平的分析方法

对天线方向图计算中涉及的最大副瓣电平的分析方法进行了探讨，提出了用方向图搜索求解最大副瓣电平；同时给出了用该方法求得在同相矩形口径两种分布形式下Ｉｎｔｅｒｃａｒｄｉｎａｌ面上的最大副瓣电子平，并给出了Ｉｎｔｅｒｃａｒｄｉｎａｌ面的定义。     

基于GRACE的京津冀地下水储量变化

基于2003—2019年GRACE陆地水储量变化数据和全球陆地水文模型（global land data assimilation system,GLDAS）数据反演京津冀地下水储量变化,运用时空分析方法对地下水等效水高变化进行时空演变特征分析。在空间变化上,整个京津冀地下水等效水高变化速率约为-51.77 mm/a,其中：北京市变化速率最低,约为-38.15 mm/a;天津市变化速率最高,约为-62.85 mm/a;河北省变化速率与区域平均变化水平相当,约为-52.42 mm/a。基于Sen Slope和Mann-Kendall非参数检验法分析得出西部、西南部和中部地区地下水等效水高下降[JP]趋势最明显,东北部下降趋势最小。在时间变化上,地下水等效水高变化具有一定的季节性规律：夏季变化速率最大,约为-75.99 mm/a;冬季变化速率最小,约为-37.24 mm/a;春秋两季的变化速率大致相同,分别为-52.34 mm/a和-48.21 mm/a。在影响因素分析中,人类活动是引起京津冀地区地下水等效水高变化的主要因素。研究结果可为科学掌握京津冀地下水储量时空变化规律提供数据支撑。     

Incorporating statistical information into expert classification systems to reduce classification costs

Interactive expert systems seek relevant information from a user in order to answer a query or to solve a problem that the user has posed. A fundamental design issue for such a system is therefore itsinformation-seeking strategy, which determines the order in which it asks questions or performs experiments to gain the information that it needs to respond to the user. This paper examines the problem of optimal knowledge acquisition through questioning in contexts where it is expensive or time-consuming to obtain the answers to questions. An abstract model of an expert classification system — considered as a set of logical classification rules supplemented by some statistical knowledge about attribute frequencies — is developed and applied to analyze the complexity and to present constructive algorithms for doing probabilistic question-based classification. New heuristics are presented that generalize previous results for optimal identification keys and questionnaires. For an important class of discrete discriminant analysis problems, these heuristics find optimal or near-optimal questioning strategies in a small fraction of the time required by an exact solution algorithm.     

Selection of optimized features for fusion of palm print and finger knuckle‐based person authentication

The impact of digital technology in biometrics is much more efficient at interpreting data than humans, which results in completely replacement of manual identification procedures in forensic science. Because the single modality‐based biometric frameworks limit performance in terms of accuracy and anti‐spoofing capabilities due to the presence of low quality data, therefore, information fusion of more than one biometric characteristic in pursuit of high recognition results can be beneficial. In this article, we present a multimodal biometric system based on information fusion of palm print and finger knuckle traits, which are least associated to any criminal investigation as evidence yet. The proposed multimodal biometric system might be useful to identify the suspects in case of physical beating or kidnapping and establish supportive scientific evidences, when no fingerprint or face information is present in photographs. The first step in our work is data preprocessing, in which region of interest of palm and finger knuckle images have been extracted. To minimize nonuniform illumination effects, we first normalize the detected circular palm or finger knuckle and then apply line ordinal pattern (LOP)‐based encoding scheme for texture enrichment. The nondecimated quaternion wavelet provides denser feature representation at multiple scales and orientations when extracted over proposed LOP encoding and increases the discrimination power of line and ridge features. To best of our knowledge, this first attempt is a combination of backtracking search algorithm and 2D²LDA has been employed to select the dominant palm and knuckle features for classification. The classifiers output for two modalities are combined at unsupervised rank level fusion rule through Borda count method, which shows an increase in performance in terms of recognition and verification, that is, 100% (correct recognition rate), 0.26% (equal error rate), 3.52 (discriminative index), and 1,262 m (speed).     

入侵检测主流技术及发展动态

入侵检测技术是网络安全的主要技术和网络研究的热点,入侵检测方法包括基于数据挖掘、粗糙集、模式识别、支持向量机和人工免疫等主要技术,详细分析了各种检测方法在入侵检测应用中的优缺点。通过回顾研究人员近期的研究成果,提出了该技术的主要发展方向,为进一步研究提供参考。