Modelling particulate erosion–corrosion regime transitions for Al/Al2O3 and Cu/Al2O3 MMCs in aqueous conditions

Very little research effort has been directed at development of models of erosion–corrosion of composite materials. This is because, in part, the understanding of the erosion–corrosion mechanisms of such materials is poor. In addition, although there has been a significant degree of effort in the development of models for erosion of MMCs, there are still difficulties in applying such models to the laboratory trends on erosion rate.In this paper, the methodology for mapping erosion–corrosion processes in aqueous slurries was extended to particulate composites. An inverse rule of mixtures was used for the construction of the erosion model for the particulate MMCs. The corrosion rate calculation was evaluated with reference to the matrix material.The erosion–corrosion maps for composites showed significant dependency on pH and applied potential. In addition, the corrosion resistance of the matrix material was observed to affect the regime boundaries. Materials maps were generated based on the results to show the optimum composite composition for exposure to the environment.     

Mammalian Navigation,Neural Models and Biorobotics

Within their home range, rodents and other mammals navigate by updating their position through (internal) signals derived from locomotion and by using landmark-place associations. Single unit recordings in freely moving rats show that motion cues and external, mainly visual information act on place and head direction cells in the hippocampus and functionally related brain areas. Currently, a number of partially converging and diverging neural network models aim at representing the neural system that controls rodent navigation. It is argued that the attempt to build self-steering robots on the basis of behavioural and neurophysiological results from rodents and of computer simulations of these results is premature, given the lack of consensus in the literature on mammalian navigation.     

A new method for assessing the trophic state of large dams in Cyprus using satellite remotely sensed data

A timely low-cost method providing information on water quality and trophic state to various users of reservoir or dam water is a must. Conventional methods involved tedious and expensive in situ and laboratory studies. Satellite-borne sensors have the capability of providing repetitive, low-cost, multispectra, timely and reliable information over areas. This paper shows the development of a new method for assessing the trophic state in inland water bodies such as dams. The method is based on matching the atmospheric corrected reflectance values obtained from Landsat-5 Thematic Mapper (TM) image data with the defined spectral signature ranges obtained from ground spectro-radiometric measurements in order to assess the trophic state conditions. The proposed method has been applied to Landsat TM and Enhanced Thematic Mapper (ETM) satellite images of the Kourris and Asprokremmos Dams in Cyprus, acquired during the winter, spring, summer and autumn period. The reflectance values for the images acquired on 3 June 1985, 11 September 1998, 11 May 2000 and 31 January 2001 for the Asprokremmos Dam were found to be 4.5, 3.5, 3.7 and 11.2%, and those for the Kourris Dam were found to be 5, 3.5, 3.1 and 5.2%, respectively. Reflectance values between 3 and 7% correspond to a eutrophic state and values >7% to a hypertrophic state. The results obtained from the proposed method were found to comply with those found using the trophic state index (TSI) approach. For example, the trophic state for the Landsat TM images of Asprokremmos Dam acquired on 11 May 2000 and 31 January 2001, was determined to be TSI=68 and 79, respectively, using the available secchi disc depths (SDDs) and the Carlson TSI. Such values correspond to eutrophic and hypetrophic trophic states that comply with the same outcomes found from the proposed method.     

Fuzzy Cognitive Maps for stereovision matching

This paper outlines a method for solving the stereovision matching problem using edge segments as the primitives. In stereovision matching the following constraints are commonly used: epipolar, similarity, smoothness, ordering and uniqueness. We propose a new matching strategy under a fuzzy context in which such constraints are mapped. The fuzzy context integrates both Fuzzy Clustering and Fuzzy Cognitive Maps. With such purpose a network of concepts (nodes) is designed, each concept represents a pair of primitives to be matched. Each concept has associated a fuzzy value which determines the degree of the correspondence. The goal is to achieve high performance in terms of correct matches. The main findings of this paper are reflected in the use of the fuzzy context that allows building the network of concepts where the matching constraints are mapped. Initially, each concept value is loaded via the Fuzzy Clustering and then updated by the Fuzzy Cognitive Maps framework. This updating is achieved through the influence of the remainder neighboring concepts until a good global matching solution is achieved. Under this fuzzy approach we gain quantitative and qualitative matching correspondences. This method works as a relaxation matching approach and its performance is illustrated by comparative analysis against some existing global matching methods.     

基于Google Maps API的车辆监控管理系统设计与实现

车辆实时监控是车队现代化管理的重要手段,能有效提高车队的生产力。本文基于CoogleMapsAPI和Ajax技术设计车辆监控平台和数据通信服务,涉及GPS数据采集服务、协议解码、实时车辆定位、轨迹回放、围栏设置等功能的设计和实现方法,为车辆监控平台的设计提供参考。     

In search of better route guidance instructions

Safety concerns have prompted designers of in-vehicle route guidance and information systems (IVRGIS) to make more use of an ‘audible interface’ to convey guidance instructions. Previous research has shown that, contrary to expectations, detailed guidance instructions can have a detrimental effect upon wayfinding performance, particularly for elderly individuals. In response to these findings a second series of experiments was carried out to try to improve the effectiveness of route guidance. Using the same procedure, 40 male and 40 female drivers aged 18–35 years watched video footage of journeys through an unfamiliar area, while hearing guidance that linked direction instructions to landmarks visible at the decision point. Results showed that those who heard these amended instructions performed significantly better than other groups at a wide range of tasks designed to measure the spatial knowledge they had acquired. This group performed better than groups who heard nothing, and groups who heard full guidance. The results support the view that, whereas full guidance instructions can have a negative impact upon wayfinding performance, less complex instructions that link landmarks to directions have the capacity to enhance wayfinding performance. This is because instructions of this form strengthen the associations made between directions to be taken and the spatial location of these turns, resulting in the formation of a strong representation of the route. The results also showed that those who had been driving for 1 year or less were significantly less accurate at these tasks than those with more driving experience. This result has important implications for the widespread implementation and use of IVRGIS: suggesting that, for newly qualified drivers, who have not yet developed the ability to attend to and process information while controlling the vehicle, attending to route guidance instructions might have a detrimental effect upon driver safety.     

农产品价格信息采集与预警系统设计与实现

为了实现农产品价格信息采集发布的及时性和有效性,提高农产品数据质量,提出一种农产品信息采集与预警系统的设计方法.通过运用Google Maps提供的应用程序开发接口和ASP.NET技术,并集成移动通讯技术和智能客户端技术,设计了农产品信息的采集、处理、发布,系统数据的预警以及基础数据维护等功能模块,保证了系统的实用性、兼容性和可扩展性.实验结果表明,在农产品价格信息采集方面,该系统实现了农产品价格信息的实时采集、处理、发布及预警功能,保证了数据的有效性和准确性,解决了农产品价格信息采集的滞后性等问题,有利于农产品信息的快速交流.     

Quality assessment of several methods to recover surface reflectance using synthetic imaging spectroscopy data

A synthetic data spectral cube that represents at-sensor radiance data of AVIRIS was used to examine the accuracy of several methods to recover absolute surface reflectance data of terrestrial targets. Soil and vegetation targets, selected to represent the images of ground variation and their spectra, were retrieved using HATCH, Empirical Line (EL) and their hybrids methods. After a synthetic radiance data cube was generated, reflectance recovery was carried out and compared with the true (input) reflectance information. It was found that even under controlled and ideal conditions, the spectral recovery using HATCH code provided differences of up to 40%. The EL methods, using the two end-members that represent the scene reduced this difference to about 4%, and in some cases, even to 0.1% It was found that selecting the calibration targets over low water vapor content improved the results. Applying EL on radiance data provided a severe difference of more than 200% in areas located outside the calibration target water vapor zone. Only over similar water vapor zones were the EL methods found to reasonably recover the surface reflectance. Examining the spectral variability in the calibration targets showed that using of spectral features targets with relative spectral similarity is almost as effective as using spectrally featureless targets for the EL process. Applying EL, using external spectral information of possible known targets, revealed a relatively high difference, as compared to the true reflectance data. However, thematic analysis using a SAM classifier proved that even under non-ideal conditions, the EL correction can yield a reasonable spatial mapping capability relative to those obtained under real reflectance domains. It was concluded that EL must be run on reflectance data (generated from absolute based method) over low water vapor zones to provide the most precise reflectance information. Also, it was found that it is not mandatory to select calibration targets that are totally featureless or characterized by low or high albedo response.     

SOM网络在透平机械状态监测中的应用

讨论了SOM网络的可视化技巧,结合该技巧研究了SOM网络在透平机械状态监测中的应用。仿真分析和实例研究表明,应用SOM网络能较好地识别出透平机械的不同状态,并及时监测到透平机械状态发生的变化。     

基于Google Maps API的高速公路WebGIS设计与应用

设计了基于Google Maps API技术的WebGIS系统,同时讨论了Google Maps的定制方法和功能设计,给出了定制设计的部分代码。文章结合高速公路WebGIS的设计实例,给出了整体系统示意图并对系统的各项功能做了详细介绍。