Reliability measure assignment to sonar for robust target differentiation

This article addresses the use of evidential reasoning and majority voting in multi-sensor decision making for target differentiation using sonar sensors. Classification of target primitives which constitute the basic building blocks of typical surfaces in uncluttered robot environments has been considered. Multiple sonar sensors placed at geographically different sensing sites make decisions about the target type based on their measurement patterns. Their decisions are combined to reach a group decision through Dempster-Shafer evidential reasoning and majority voting. The sensing nodes view the targets at different ranges and angles so that they have different degrees of reliability. Proper accounting for these different reliabilities has the potential to improve decision making compared to simple uniform treatment of the sensors. Consistency problems arising in majority voting are addressed with a view to achieving high classification performance. This is done by introducing preference ordering among the possible target types and assigning reliability measures (which essentially serve as weights) to each decision-making node based on the target range and azimuth estimates it makes and the belief values it assigns to possible target types. The results bring substantial improvement over evidential reasoning and simple majority voting by reducing the target misclassification rate.     

空间目标融合识别算法及实验研究

提出了基于红外与可见光图像的空间目标融合识别算法。算法针对空间目标的物理特征,利用红外和可见光图像提供的互补信息进行空间目标融合识别。方法以空间卫星为识别目标,采用不变矩和仿射不变矩来描述目标特征,提出了基于红外和可见光的特征级和决策级融合识别方案,并进行了半物理仿真实验和分析。实验证明这两种基于红外和可见光的融合识别算法可明显改善目标识别的精度和可靠性。     

基于可穿戴传感器的人体活动识别研究综述

人体活动识别（HAR）在医疗、安全、娱乐等方面有着广泛的应用。随着传感器器件的发展,各类能准确采集人体行为活动数据的传感器在手环、手表、手机等可穿戴设备上得到了广泛使用,相比基于视频图像的行为识别方法,基于传感器的行为识别具有成本低、灵活、可移植性好的特点,因此,基于可穿戴传感器的人体活动识别研究成为行为识别中的研究热点。介绍了人体活动识别研究中原始数据采集、特征提取、特征选择以及分类方法,对识别流程中每一部分常用的技术以及研究现状进行了综述总结,最后分析人体活动识别研究当前存在的主要问题并展望了今后可能的研究方向。     

基于分段平均微分值法的动态检测识别系统

本文将动态检测方法应用到电子鼻技术中,采用半导体气敏传感器MQ131、MQ135、MQ138组成阵列,设计了实时的动态检测、数据采集系统,测试了甲苯、乙酸酐、乙醚、丙酮四种气体.并且针对气体在动态检测方式下的气敏机理,提出了一种新的特征提取方法--分段平均微分值法,此方法既能获取动态响应过程的主流特征信息又有效地削弱了浓度的影响.最后,将分段平均微分法结合BP神经网络模式识别技术对不同浓度下的甲苯、乙酸酐、乙醚、丙酮四种气体进行了识别,识别率可达91.67%.     

Ranging through Gabor logons-a consistent, hierarchical approach

In this work, the correspondence problem in stereo vision is handled by matching two sets of dense feature vectors. Inspired by biological evidence, these feature vectors are generated by a correlation between a bank of Gabor sensors and the intensity image. The sensors consist of two-dimensional Gabor filters at various scales (spatial frequencies) and orientations, which bear close resemblance to the receptive field profiles of simple V1 cells in visual cortex. A hierarchical, stochastic relaxation method is then used to obtain the dense stereo disparities. Unlike traditional hierarchical methods for stereo, feature based hierarchical processing yields consistent disparities. To avoid false matchings due to static occlusion, a dual matching, based on the imaging geometry, is used.     

A robust method for coarse classifier construction from a large number of basic recognizers for on-line handwritten Chinese/Japanese character recognition

In this paper, a systematic method is described that constructs an efficient and a robust coarse classifier from a large number of basic recognizers obtained by different parameters of feature extraction, different discriminant methods or functions, etc. The architecture of the coarse classification is a sequential cascade of basic recognizers that reduces the candidates after each basic recognizer. A genetic algorithm determines the best cascade with the best speed and highest performance. The method was applied for on-line handwritten Chinese and Japanese character recognitions. We produced hundreds of basic recognizers with different classification costs and different classification accuracies by changing parameters of feature extraction and discriminant functions. From these basic recognizers, we obtained a rather simple two-stage cascade, resulting in the whole recognition time being reduced largely while maintaining classification and recognition rates.     

基于改进视觉词袋模型的水声目标识别

水声目标识别的任务是通过采集到水声目标的信号来对目标进行分类,在海洋勘探,监听技术等领域有着非常重要和广泛的应用.由于海洋环境的复杂性,以及船只目标发动机的多样性以及噪声的存在,水声目标识别是一个困难的任务.传统的特征提取方法无法提取到足够有效的特征表示,充分地表示目标.为了解决这个问题,本文提出了一种基于改进的视觉化词袋模型的水声识别算法,通过使用视觉化词袋模型对频谱图进行高维的特征提取,然后使用了自然语言处理领域中常见的词频-逆文件频率(TF-IDF)算法来对得到的特征向量进行权重调整,然后输入到多层感知机中,对水声目标进行分类识别.实验结果表明,本文提出的识别算法取得了92.53％的正确率,相比于当前效果最好的深度玻尔兹曼机(DBM)算法有了明显的提升.     

基于曲率匹配的细胞几何形状特征提取方法

细胞轮廓的几何形状是细胞学涂片判读的重要参考,对研究宫颈病变的计算机辅助诊断具有重要意义。针对现有基于形状模板匹配的几何形状识别方法鲁棒性较差的问题,提出了基于曲率匹配的几何形状特征提取方法,通过比较模板轮廓和待识别轮廓的曲率,计算曲率曲线之间的相似度,进而得到细胞轮廓的形状特征,并采用依次旋转轮廓选取最佳匹配的方法来解决轮廓方向不一致的问题,采用以面积等效圆的半径比作为放大比率进行轮廓缩放的方法来解决轮廓大小不一致的问题。通过相关实验证明了该方法所提取的几何形状特征具有尺度不变性和旋转不变性,并与改进Hausdorff距离进行了实验对比,结果表明提取的形状特征能更加准确地识别出细胞轮廓的几何形状。     

Comparative analysis of different approaches to target differentiation and localization with sonar

This study compares the performances of different methods for the differentiation and localization of commonly encountered features in indoor environments. Differentiation of such features is of interest for intelligent systems in a variety of applications such as system control based on acoustic signal detection and identification, map building, navigation, obstacle avoidance, and target tracking. Different representations of amplitude and time-of-flight measurement patterns experimentally acquired from a real sonar system are processed. The approaches compared in this study include the target differentiation algorithm, Dempster-Shafer evidential reasoning, different kinds of voting schemes, statistical pattern recognition techniques (k-nearest neighbor classifier, kernel estimator, parameterized density estimator, linear discriminant analysis, and fuzzy c-means clustering algorithm), and artificial neural networks. The neural networks are trained with different input signal representations obtained using pre-processing techniques such as discrete ordinary and fractional Fourier, Hartley and wavelet transforms, and Kohonen's self-organizing feature map. The use of neural networks trained with the back-propagation algorithm, usually with fractional Fourier transform or wavelet pre-processing results in near perfect differentiation, around 85% correct range estimation and around 95% correct azimuth estimation, which would be satisfactory in a wide range of applications.     

SAR图像舰船目标检测的信息几何方法

目的 舰船目标检测是合成孔径雷达（SAR）图像在海事监测领域中的一项重要应用。由于海面微波散射的复杂性,SAR图像中海杂波分布具有非均匀性、非平稳性等特点,传统的基于恒虚警率（CFAR）的SAR图像舰船检测算法难以适应复杂多变的海杂波环境,无法实现实时有效的智能检测任务。鉴于此,本文提出了基于信息几何的SAR图像船舰目标检测方法,旨在分析统计流形及其在参数空间中的几何结构,探讨信息几何在SAR图像目标检测应用中的切入点,从新的角度提升该应用领域的理论与技术水平。方法 首先,运用威布尔分布族对SAR图像中的海杂波进行统计建模,利用最大似然方法估计SAR图像局部邻域像素的分布参数,并将不同参数下的统计分布作为威布尔流形上的不同点;其次,融合高斯分布的费歇耳度量来构造威布尔流形空间中概率分布之间的测度,实现目标与背景区域的差异性表征;最后,利用最大类间方差法,实现SAR图像舰船目标检测。结果 实验和分析表明,相比于传统的基于恒虚警率的检测算法,信息几何方法可以有效地区分舰船目标和海杂波背景,降低虚警率,实现舰船目标显著性表示与检测。结论 由于舰船目标的复杂后向散射特性,如何有效地表征这一差异,是统计类检测算法的关键所在。本文依据信息几何理论,将概率分布族的参数空间视为微分流形,在参数流形上构造合适的黎曼度量,对SAR图像中各像素局部邻域进行测度表征,可以显著性表示目标与背景杂波之间的统计差异,实现舰船目标检测。     

Design, fabrication, and testing of VDP MEMS pressure sensors

In this paper, a four-terminal piezoresistive sensor commonly known as a van der Pauw (VDP) structure is presented for its application to MEMS pressure sensing. In a recent study, our team has determined the relation between the biaxial stress state and the piezoresistive response of a VDP structure by combining the VDP resistance equations with the equations governing silicon piezoresistivity and has proposed a new piezoresistive pressure sensor. It was observed that the sensitivity of the VDP sensor is over three times higher than the conventional filament type Wheatstone bridge resistor. To check our theoretical findings, we fabricated several (100) silicon diaphragms with both the VDP sensors and filament resistor sensors on the same wafer so both the sensor elements have same doping concentration. Several diaphragms had VDP sensors of different sizes and orientations to find out their geometric effects on pressure sensitivity. The diaphragms were subjected to known pressures, and the pressure sensitivities of both types of sensors were measured using an in-house built calibration setup. It was found that the VDP devices had a linear response to pressure as expected, and were more sensitive than the resistor sensors. Also, the VDP sensors provided a number of additional advantages, such as its size independent sensitivity and simple fabrication steps due to its simple geometry.     

Fusion of FLIR automatic target recognition algorithms

In this paper, we investigate several fusion techniques for designing a composite classifier to improve the performance (probability of correct classification) of forward-looking infrared (FLIR) automatic target recognition (ATR). The motivation behind the fusion of ATR algorithms is that if each contributing technique in a fusion algorithm (composite classifier) emphasizes on learning at least some features of the targets that are not learned by other contributing techniques for making a classification decision, a fusion of ATR algorithms may improve overall probability of correct classification of the composite classifier. In this research, we propose to use four ATR algorithms for fusion. The individual performance of the four contributing algorithms ranges from 73.5% to about 77% of probability of correct classification on the testing set. The set of correctly classified targets by each contributing algorithm usually has a substantial overlap with the set of correctly identified targets by other algorithms (over 50% for the four algorithms being used in this research). There is also a significant part of the set of correctly identified targets that is not shared by all contributing algorithms. The size of this subset of correctly identified targets generally determines the extent of the potential improvement that may result from the fusion of the ATR algorithms. In this research, we propose to use Bayes classifier, committee of experts, stacked-generalization, winner-takes-all, and ranking-based fusion techniques for designing the composite classifiers. The experimental results show an improvement of more than 6.5% over the best individual performance.     

Aerobic activity monitoring: towards a long-term approach

With recent progress in wearable sensing, it becomes reasonable for individuals to wear different sensors all day, and thus, global activity monitoring is establishing. The goals in global activity monitoring systems are among others to tell the type of activity that was performed, the duration and the intensity. With the information obtained this way, the individual’s daily routine can be described in detail. One of the strong motivations to achieve these goals comes from healthcare: To be able to tell if individuals were performing enough physical activity to maintain or even promote their health. This work focuses on the monitoring of aerobic activities and targets two main goals: To estimate the intensity of activities, and to identify basic/recommended physical activities and postures. For these purposes, a dataset with 8 subjects and 14 different activities was recorded, including the basic activities and postures, but also examples of household (ironing, vacuum cleaning), sports (playing soccer, rope jumping), and everyday activities (ascending and descending stairs). Data from 3 accelerometers—placed on lower arm, chest, and foot—and a heart rate monitor were analyzed. This paper presents the entire data processing chain, analyses and compares different classification techniques, concerning also their feasibility for portable online activity monitoring applications. Results are presented with different combinations of the sensors. For the intensity estimation task, using the sensor setup composed of the chest accelerometer and the HR-monitor is considered the most efficient, achieving a performance of 94.37 %. The overall performance on the activity recognition task, using all available sensors, is 90.65 % with boosted decision trees—the classifier achieving the best classification results within this work.     

Using data mining for digital ink recognition: Dividing text and shapes in sketched diagrams

The low accuracy rates of text-shape dividers for digital ink diagrams are hindering their use in real world applications. While recognition of handwriting is well advanced and there have been many recognition approaches proposed for hand drawn sketches, there has been less attention on the division of text and drawing ink. Feature based recognition is a common approach for text-shape division. However, the choice of features and algorithms are critical to the success of the recognition. We propose the use of data mining techniques to build more accurate text-shape dividers. A comparative study is used to systematically identify the algorithms best suited for the specific problem. We have generated dividers using data mining with diagrams from three domains and a comprehensive ink feature library. The extensive evaluation on diagrams from six different domains has shown that our resulting dividers, using LADTree and LogitBoost, are significantly more accurate than three existing dividers.     

嗅觉神经网络在电子鼻识别多品牌绿茶中的应用研究

生物模式识别机理引入人工嗅觉系统将提高其仿生化程度,并被认为是有前途的传感阵列信息处理方法。本文尝试将一种嗅觉神经网络应用到电子鼻检测和识别多种品牌的绿茶气味。通过包含8个MOS型气敏传感器的自制电子鼻仪器,测量了来着不同地方的5种不同品牌的绿茶样品,在传感阵列信号稳态部分提取特征向量,并使用雷达图考察指纹图谱异同,验证传感阵列及特征提取方法的有效性。采用生物相似性学习算法训练该神经网络,考察了样本训练次数和识别率的关系,发现经过4～7次训练,该网络对这5种绿茶的识别率平均值都在97%以上。     

Stereo and Specular Reflection

The problem of accurate depth estimation using stereo in the presence of specular reflection is addressed. Specular reflection, a fundamental and ubiquitous reflection mechanism, is viewpoint dependent and can cause large intensity differences at corresponding points, resulting in significant depth errors. We analyze the physics of specular reflection and the geometry of stereopsis which lead to a relationship between stereo vergence, surface roughness, and the likelihood of a correct match. Given a lower bound on surface roughness, an optimal binocular stereo configuration can be determined which maximizes precision in depth estimation despite specular reflection. However, surface roughness is difficult to estimate in unstructured environments. Therefore, trinocular configurations, independent of surface roughness are determined such that at each scene point visible to all sensors, at least one stereo pair can produce correct depth. We have developed a simple algorithm to reconstruct depth from the multiple stereo pairs.     

Design and Construction of Electronic Nose for Multi-purpose Applications by Sensor Array Arrangement Using IBGSA

Technological progresses in the gas sensor fields provide the possibility of designing and construction of Electronic nose (E-nose) based on the Biological nose. E-nose uses specific hardware and software units; Sensor array is one of the critical units in the E-nose and its types of sensors are determined based on the application. So far, many achievements have been reported for using the E-nose in different fields of application. In this work, an E-nose for handling multi-purpose applications is proposed, and the employed hardware and pattern recognition techniques are depicted. To achieve higher recognition rate and lower power consumption, the improved binary gravitational search algorithm (IBGSA) and the K-nearest neighbor (KNN) classifier are used for automatic selecting the best combination of the sensors. The designed E-nose is tested by classifying the odors in different case studies, including moldy bread recognition in food and beverage field, herbs recognition in the medical field, and petroleum products recognition in the industrial field. Experimental results confirm the efficiency of the proposed method for E-nose realization.     

改进YOLOV3算法在行人识别中的应用

为了避免人与物体之间相互遮挡，对小目标检测不准确，以及复杂光照强度对行人检测的影响，针对这一问题，提出了一种多尺度聚类卷积神经网络MK-YOLOV3算法，来实现对行人的识别与检测。该算法是对YOLOV3进行改进，首先通过简单聚类对图像特征进行提取，得到相应的特征图，再通过抽样[K]-means聚类算法结合核函数确定锚点位置，以达到更好的聚类。针对小目标的浅层特征信息进行多尺度融合，提高小目标的检测效果。仿真结果验证了该算法在VOC数据集上对小目标识别的精度和速度上有较大提高，以及视频智能分析中有较高的召回率和精确度。