A simple method to account for topography in the radiometric correction of radar imagery

This article presents a method to study and correct radiometric distortions caused by topography in SAR images. The method is easy to implement and requires neither sophisticated software nor code-level programming. It also considers the case of a flat surface having an elevation different from the one for which calibration parameters were derived. An ortho-image of the slant range distance is used with a Digital Elevation Model to generate images of the local incident angle along the range and azimuth directions. The method compensates for variations in the terrain area of each pixel and for the angular dependence of backscatter, allowing the choice of either an empirical or semi-empirical scattering model. The method is applied to high-resolution C-SAR subsets of an agricultural area in the Central Cordillera of Costa Rica. The removal of topographic features appears excellent for local incident angles up to 80°, but small-scale structures have pronounced effects on the radar return for higher local incident angles and are not adequately corrected.     

基于正交投影校正的算法及其应用

基于正交投影的校正算法是近年来在光谱处理上显得较活跃的一种方法。本文介绍了基于正交投影的校正算法的基本原理,并对S．Wold、Fearn等人的比较成熟的5种基于正交投影的校正算法作了比较详细地介绍。最后对5种算法在谷物和柴油的近红外数据上的应用进行了比较和讨论。     

A refined jacobi-davidson method and its correction equation

A central problem in the Jacobi-Davidson method is to expand a projection subspace by solving a certain correction equation. It has been commonly accepted that the correction equation always has a solution. However, it is proved in this paper that this is not true. Conditions are given to decide when it has a unique solution or many solutions or no solution. A refined Jacobi-Davidson method is proposed to overcome the possible nonconvergence of Ritz vectors by computing certain refined approximation eigenvectors from the subspace. A corresponding correction equation is derived for the refined method. Numerical experiments are conducted and efficiency of the refined method is confirmed.     

传感网络虚假信息避免与过滤方法研究与仿真

研究网络假信息过滤控制问题,由于无线传感网络中的节点分布随机性很强,很容易被捕获造成大量的虚假信息被输入,干扰正常通信.受到节点随机性部署的限制,传统算法中缺少节点布置位置风险检测功能和信息校验功能,一旦虚假信息被注入会大幅影响通信效果.提出一种利用位置约束与虚假信息过滤的无线传感网络虚假信息过滤算法,在节点布局过程中对布局的位置信息进行校验,加入位置校验修复因子对节点位置联系进行合理的风险分析,降低节点捕获风险.运用节点信息聚类关联性的特点,对虚假信息进行校验,判断是否为真实的信息关联,过滤虚假信息.实验结果表明,过滤算法能够分布更合理的位置信息,对虚假信息过滤精度较高,同时也改善了网络的稳定性.     

Ultrasonic sensor data integration and its application to environment perception

To move in an unknown or uncertain environment, a mobile robot must collect information from various sensors and use it to construct a representation of the external world. Ultrasonic sensors can provide range data for this purpose in a simple and cost-effective way. However, most ultrasonic sensors are not sufficient for environment recognition because of their large beam opening angles. In this article the beam-opening-angle problem is solved by fusing data from multiple ultrasonic sensors. We propose two methods for sensor data fusion. One uses an artificial neural network (ANN), and the other is based on a mathematical model. Simulations and experiments show that the mathematical model is more accurate when there is no noise in the sensor readings, but the ANN method is better when the sensors are subject to much noise. To extract line segments from the ultrasonic image, we develop a line extractor that is more efficient than traditional line fitting methods in this application. Experimental results show that this method is effective for environment perception in a robotic system. © 1996 John Wiley & Sons, Inc.     

MODIS observations of the bottom topography and its inter-annual variability of Poyang Lake

Using MODIS 250-m resolution data, we developed a novel approach to derive the bottom topography of Poyang Lake, the largest freshwater lake of China (> 3000 km² at maximum inundation) for every year between 2000 and 2009. The approach differs from other traditional methods (sonar, Lidar, optical inversion, and Radar) but takes advantage of the fast-changing nature of the lake's inundation area. On every image, the water/land boundary is effectively a topographic isobath after correction for the water level gradient. Thus, the ~ 10/year carefully selected MODIS images provided incremental topographic isobaths, from which bottom topography was derived every year. Such-derived topographic maps were validated using limited historical data and other consistency checks. Most of the lake bottom showed an elevation of 12 m to 17 m (referenced against the elevation reference of the Woosung Horizontal Zero). Significant inter-annual variability of the bottom topography from 2000 to 2009 was found for some of the lake's bottom, with more areas associated with bottom elevation increases than decreases. The changes and inter-annual variability in the bottom topography were attributed to the combined effect of human activities (e.g., sand dredging and levee construction) and weather events. One example was the increased bottom elevation from 2002 to 2003, which was apparently due to the excessive precipitation in 2002 and the impoundment of the Three-Gorges Dam in 2003. The 10-year record of the bottom topography of this highly dynamic lake provides baseline information to monitor the impact of future engineering and management activities, to estimate the lake's water and sediment budgets, and to aid ship navigation.     

感知矿山物联网愿景与发展趋势

给出了矿山物联网的愿景,即实现矿山物与物相连,减少甚至消除监测盲区,运用云计算和大数据技术提取有用的监测信息,真正实现本质安全矿山;从技术和服务模式2个方面梳理了矿山物联网的发展趋势,阐述了雾计算技术、网络分形结构、矿山物体的本体描述与知识化、云计算与大数据技术等概念及其在矿山物联网中的应用与发展,对协同工作模式和购买服务模式进行了展望。     

Depth perception using blurring and its application in VLSI wafer probing

In this paper, we present a technique for measuring the amount of blur of an edge and using this information to determine the distance of a micromanipulator probe from a wafer surface in very large scale integration (VLSI) wafer probing. In this application, a soft and reliable touch of the probe with a metal pad in the wafer is a sensitive operation. The wafer is focused and several images of the probe while approaching the wafer are analyzed. In our theory, the amount of blur is calculated from the height of the step edge and the slope of the intensity profile at the zero crossing. Hence, our formula is simple and easy to use. We estimate the distance of the probe from the surface of the wafer and obtain a robust measure, i.e., one which is valid even in the presence of significant noise in the images. In order to validate our methods, we have experimented with various VLSI patterns as backgrounds.     

True multi-image alignment and its application to mosaicing andlens distortion correction

Multiple images of a scene are related through 2D/3D view transformations and linear and nonlinear camera transformations. We present an algorithm for true multi-image alignment that does not rely on the measurements of a reference image being distortion free. The algorithm is developed to specifically align and mosaic images using parametric transformations in the presence of lens distortion. When lens distortion is present, none of the images can be assumed to be ideal. In our formulation, all the images are modeled as intensity measurements represented in their respective coordinate systems, each of which is related to an ideal coordinate system through an interior camera transformation and an exterior view transformation. The goal of the accompanying algorithm is to compute an image in the ideal coordinate system while solving for the transformations that relate the ideal system with each of the data images. Key advantages of the technique presented in this paper are: (i) no reliance on one distortion free image, (ii) ability to register images and compute coordinate transformations even when the multiple images are of an extended scene with no overlap between the first and last frame of the sequence, and (iii) ability to handle linear and nonlinear transformations within the same framework. Results of applying the algorithm are presented for the correction of lens distortion, and creation of video mosaics     

Frame rate as a QoS parameter and its influence on speech perception

The preservation of QoS for multimedia traffic through a data network is a difficult problem. We focus our attention on video frame rate and study its influence on speech perception. When sound and picture are discrepant (e.g., acoustic ‘ba’ combined with visual ‘ga’), subjects perceive a different sound (such as ‘da’). This phenomenon is known as the McGurk effect. In this paper, the influence of degraded video frame rate on speech perception is studied. It is shown that, when frame rate decreases, correct hearing is improved for discrepant stimuli and is degraded for congruent (voice and picture are the same) stimuli. Furthermore, we studied the case where lip closure was always captured by the synchronization of sampling time and lip position. In this case, frame rate has little effect on mishearing for congruent stimuli. For discrepant stimuli, mishearing is decreased with degraded frame rate. These results indicate that the stiff motion of lips resulting from low frame rate cannot give enough labial information for speech perception. In addition, the effect of delaying the picture to correct for low frame rate was studied. The results, however, were not as definitive as expected, because of compound effects related to the synchronization of sound and picture. Finally, we inspected the still pictures of normal Japanese speech and determined a lower limit of frame rate from the view point of assisting hearing.     

Network recognition of an MOS integrated circuit from the topography of its masks

Technological data and geometric dimensions of mask patterns define the properties of integrated circuits. These parameters cannot, however, be used directly to analyse the circuits. The MASOB computer program can be used for recognizing the topology and parameters of a lumped-parameter network matched to the integrated circuits. The network can then be readily analysed. Silicon gate MOS technology is assumed. The paper presents the principles of the basic algorithms of the MASOB computer program, written in FORTRAN, and an example of application.     

传统NIDS漏报和误报起因及改进技术

传统的网络入侵检测系统大都采用模式匹配的方法进行入侵检测,有着非常高的漏报率和误报率。本文通过对模式匹配算法检测过程的描述,对其产生漏报和误报的原因进行了分析。针对模式匹配算法带来的高漏报率和误报率,引入了协议分析的方法。协议分析方法通过辨别数据包的协议类型,然后使用相应的数据分析程序进行检测。这种方法可以大幅度地降低漏报率和误报率,大大地提高了入侵检测系统的效率。     

多波束天线通道幅相一致性校正及实现

本文针对多波束天线接收机的通道幅相一致性校正,提出了一种基于自适应算法的校正方法并在FPGA中实现了该方法.在满足系统要求的前提下,该方法不但实现起来相对容易,而且算法的精度和动态范围也有一定的保证.仿真和试验结果表明,该方法是可行的.     

Characterization of the spatial variability of surface topography and moisture content and its influence on potato crop yield

ABSTRACT

Addressing the cause of the spatial variability of crop (Solanum tuberosum L.) yield is of a great importance to farmers who plan to apply precision agriculture techniques. Therefore, a study on two centre pivot irrigated potato fields in Saudi Arabia was conducted to detect and assess the spatial dependencies among three variables (surface topography, moisture content, and potato yield) and to examine the influence of surface topography and moisture on the potato yield. In addition to surface elevation data in the form of digital elevation model, cloud-free satellite images of Landsat-8 with a spatial resolution of 30 m were acquired throughout the study period. Samples of potato yield were collected 2 days prior to the harvest time and upscaled into yield maps using the interpolation technique in ArcGIS software program. Soil field capacity (F_C) and permanent wilting point (PWP) were determined for the study area and utilized to generate moisture content maps using thermal inertia method. The study employed the bivariate Moran’s Index (Moran’s I) and the Bivariate Local Indicator of Spatial Autocorrelation in order to measure the strength of the spatial autocorrelation and to quantify the spatial dependency between each two of the acquired variables. The interpretation of the mapped topography, cumulative moisture, and yield revealed a substantial agreement along the spatial distribution of the high moisture and yield values with the adverse value of the surface elevation. Results of the spatial autocorrelation indicated that the spatial patterns of moisture-yield over the two study fields were strongly associated with high-high clustering level covering an area of 42% of field 68-S and 39% of field 44-S, while topography-yield patterns over field 68-S and 44-S covered only 25% and 22% of the areas, respectively, with a confidence level of 0.01 for all patterns at both fields.     

On the Behavior of True and False

Uzquiano (Analysis 70:39–44, 2010) showed that the Hardest Logic Puzzle Ever (HLPE) [in its amended form due to Rabern and Rabern (Analysis 68:105–112, 2008)] has a solution in only two questions. Uzquiano concludes his paper by noting that his solution strategy naturally suggests a harder variation of the puzzle which, as he remarks, he does not know how to solve in two questions. Wheeler and Barahona (J Philos Logic, to appear, 2011) formulated a three question solution to Uzquiano’s puzzle and gave an information theoretic argument to establish that a two question solution for Uzquiano’s puzzle does not exist. However, their argument crucially relies on a certain conception of what it means to answer self-referential yes–no questions truly and falsely. We propose an alternative such conception which, as we show, allows one to solve Uzquiano’s puzzle in two questions. The solution strategy adopted suggests an even harder variation of Uzquiano’s puzzle which, as we will show, can also be solved in two questions. Just as all previous solutions to versions of HLPE, our solution is presented informally. The second part of the paper investigates the prospects of formally representing solutions to HLPE by exploiting theories of truth.     

OCR error correction using correction patterns and self-organizing migrating algorithm

Optical character recognition (OCR) systems help to digitize paper-based historical achieves. However, poor quality of scanned documents and limitations of text recognition techniques result in different kinds of errors in OCR outputs. Post-processing is an essential step in improving the output quality of OCR systems by detecting and cleaning the errors. In this paper, we present an automatic model consisting of both error detection and error correction phases for OCR post-processing. We propose a novel approach of OCR post-processing error correction using correction pattern edits and evolutionary algorithm which has been mainly used for solving optimization problems. Our model adopts a variant of the self-organizing migrating algorithm along with a fitness function based on modifications of important linguistic features. We illustrate how to construct the table of correction pattern edits involving all types of edit operations and being directly learned from the training dataset. Through efficient settings of the algorithm parameters, our model can be performed with high-quality candidate generation and error correction. The experimental results show that our proposed approach outperforms various baseline approaches as evaluated on the benchmark dataset of ICDAR 2017 Post-OCR text correction competition.