基于梯度博弈的RFID室内定位算法

随着普适计算的不断发展,室内定位技术成为了当今研究的热点问题。室内空间的复杂性使得室内空间的定位精度一直无法满足应用的需求。为了获得更加高效稳定的算法,提出了一种基于梯度和博弈论的室内定位算法,其能够较为有效地提高室内空间的定位精度。在算法中,提出了一种室内的符号划分方法,并利用其对室内空间进行了分割以辅助定位算法。最后以室内为实验环境对算法进行了验证,分析结果表明,该算法拥有良好的定位效果,并且相对于现有算法更稳定。     

基于感知规则集策略的约束空间RFID室内符号定位算法

随着普适计算的不断发展,室内定位技术的研究也成为当今研究的热点问题。室内定位技术的不断进步使得RFID也开始部署到各种各样的室内场景。为了提高室内空间中的定位精度,提出了一种基于感知规则集策略的约束空间RFID室内符号定位方法。算法基于室内空间中的符号,通过定义感知情况来确立定位规则,使得算法具有良好的室内空间适应性,且使用少量的阅读器即可实现较高精度的定位。为了提高定位精度,引入了感知规则集的概念,对场景中的情况抽象提取,进一步增加算法定位精度。最后,以约束空间中的室内场景作为实验环境对算法进行验证,分析结果表明,在室内空间中算法的定位精度及抗干扰能力优于现有算法。     

基于改进支持向量机的Wi-Fi室内定位算法

针对室内复杂环境下无线信号不稳定、传统支持向量机定位算法计算复杂度高等难题,为了提高室内的定位精度,提出一种改进支持向量机的Wi-Fi室内定位算法。采用核主成分分析对特征进行降维处理,提取有用信息、降低计算量,采用支持向量机构建定位特征与物理位置的非线性映射模型,并采用粒子群算法对模型参数进行优化,进行了仿真实验。结果表明,该算法提高了室内定位精度和效率。     

三维空间RFID定位系统方法及其应用研究

为了提高室内定位系统的性能, 提出了一种三维空间内利用RFID技术定位目标物体的算法。算法通过接收信号强度获得天线和目标标签之间的距离, 然后采用梯度下降法计算得到目标电子标签的位置。仓库定位网络实验结果显示, 所建立的算法可以逐步逼近目标标签的真实位置, 有效提高了三维空间内目标的定位精度, 在仓库管理等室内定位系统中具有较强的实用性。     

基于权重参数实时更新的室内定位算法

为了提高室内节点的定位精度,提出一种基于权值参数实时更新的室内定位算法。选择3个最能反映待定位点信息的访问接入点,实时获取测距模型的参数,并采用最小二乘支持向量机对测距进行补偿,得到距离权重,三边定位算法根据权重对节点进行定位,并对计算中的距离进行加权处理,采用卡尔曼滤波法对定位误差的进行校正。实验结果表明,该算法可以较好地降低环境变化和测量误差对定位的不利影响,提高了室内节点的定位精度。     

基于无线传感器网络的自适应声源定位算法

基于声源能量的无线传感器网络（ WSNs）最大似然定位算法抗噪声干扰能力强,定位精度高,同时适用于多个目标定位,但是计算量大,不适用于实时定位。针对现有算法的缺点,提出了一种基于自适应迭代的最大似然定位算法。该算法将代价函数作为目标函数,在给定的梯度误差范围内自适应地搜索目标位置。为了提高算法的收敛速度和定位精度,提出了基于Sigmoid函数的变步长的搜索算法。仿真实验结果表明：与最大似然定位算法相比,自适应迭代算法运算量小,定位精度高,能满足对目标定位精度和速度要求较高的场合,具有一定的实际应用意义。     

基于XGBoost的客户所在店铺WiFi定位技术研究

为了减小室内复杂环境等因素对WiFi定位的影响,降低定位成本,提高定位精度并缩小定位区域,通过对室内定位系统和相关机器学习算法进行深入分析和探讨,提出了一种基于XGBoost的WiFi室内定位算法。根据WiFi信号强度分布不均匀的特点,此算法通过提取WiFi强度特征,并利用XGBoost分类器对信号来源进行定位。实验结果表明,该定位算法在WiFi强度特征可检测时达到了87.72%的定位精度,达到预期的定位效果,同时定位时间较短,稳定性较好,可以基本满足实时定位的要求。     

一种改进的室内无线定位算法

为提高室内无线定位精度并降低算法复杂度,提出一种改进的室内无线定位算法,包含2种分支算法。以视距路径数为标准,将室内无线环境划分为非视距污染较轻和较重2种环境。对污染较轻的环境,采用改进的Fang-Taylor级联算法;对污染较重的环境,采用新的迭代定位算法。仿真实验结果表明,该算法能达到甚至超过同类算法的定位精度,且适应多种室内无线环境,提高对环境的鲁棒性。     

基于UWB的LSM-Taylor级联车辆定位算法

为了满足智能车在室内的高精度定位要求,针对室内的伪三维定位场景,提出了一种基于超宽带(Ultra Wideband,UWB)的LSM-Taylor级联车辆定位算法.该算法以到达时间差(Time Difference of Ar-rival,TDOA)为定位方式,以多基站最小二乘法(Least Square Method,LSM)定位算法的计算结果为初始值,通过Taylor级数迭代估计车辆的精确位置.该算法主要解决多径效应和非视距产生的测量误差对定位精度的影响,从而提高定位精度.在仿真结果中,相比LSM定位算法,LSM-Taylor级联定位算法的定位结果分布更加紧密,定位精度更高.实际测试结果表明,该定位算法的均方根误差(Root Mean Squared Error,RMSE)在10 cm以下,能满足智能驾驶中的室内定位要求,验证了该方法的有效性.     

信号强度与运动传感器融合的智能手机室内定位算法

利用智能手机传感器实现高精度跟踪定位已经成为一个研究热点,本文针对室内定位中由于手机的运动引起采集信号强度不稳定造成的定位误差大的问题,提出了基于信号强度与加速度梯度融合综合的新的测距算法,结合手机方向信息、地图信息、信号强度的分布信息,利用测距信息与地图匹配算法,实现对智能手机的精确定位。在实验测试中,该算法平均定位精度为1.2m, 3.5m以下定位精度达95%。本算法有效的提高了智能手机的室内定位精度,并且相比指纹库定位算法减少了搜索次数,提高了定位速度。     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).