基于混合粒子滤波的运动火焰跟踪算法

提出一种基于混合粒子滤波的运动火焰跟踪算法。针对通用粒子滤波算法计算量大的问题,提出了混合粒子滤波,将Mean Shift算法嵌入到粒子滤波中,并用自适应运动模型和目标模型自动更新的策略改善算法性能。基于混合粒子滤波提出了火焰识别和火焰跟踪相结合的运动火焰自动跟踪算法,先火焰识别,再火焰跟踪,且跟踪时,如果估计目标与模型的相似度小于阈值则切换到火焰识别阶段。识别与跟踪的相互切换保证了跟踪结果的正确性。实验结果表明混合粒子滤波具有很好的跟踪效果,与粒子滤波和Mean Shift算法相比,提高了跟踪精度;基于混合粒子滤波的火焰跟踪算法能够跟踪复杂环境下的运动火焰,提供火焰的精确位置。     

基于背景优化的Mean Shift目标跟踪算法

针对传统的Mean Shift算法在目标快速运动且背景区域变化较大时,容易丢失跟踪目标的问题,提出了一种基于背景优化的Mean Shift目标跟踪算法。该算法引入混合直方图并对直方图重新量化,再通过减少背景像素在概率密度函数(PDF)中的权重来对背景进行优化,从而降低背景区域对跟踪的影响。实验结果表明,当目标快速运动,且背景区域变化较大时,该算法仍然能够实现对运动目标的准确跟踪。     

基于SIFT特征一致性的目标跟踪算法

针对光照条件突然变化情况下混合目标模型Mean Shift算法无法准确跟踪目标的缺点,提出了一种基于SIFT特征一致性的目标跟踪算法.算法用SIFT特征来匹配帧间的感兴趣区域,同时使用包含初始帧信息和前一帧信息的混合目标模型Mean Shift算法计算帧间感兴趣区域的直方图,以直方图分布距离最小为原则计算Mean Sh...     

基于改进Mean Shift视频目标跟踪算法的研究

针对传统的Mean Shift目标跟踪算法计算量大,难以实现对目标的实时跟踪,并且容易造成目标丢失,降低了目标跟踪的精确度;鉴于此,提出了一种改进Mean Shift的视频目标跟踪算法;首先,建立视频运动速度的系统动态模型,以便减少粒子维数粒子的数量;其次,在Mean Shift算法中核函数在目标特性的直方图表示的基础上来构建系统的观测值的获取;最后,利用Mean Shift算法的聚类作用,将粒子聚集在真实位置的区域以便更加靠近其跟踪目标;实验结果表明,验证了该算法在视频目标跟踪中,能够有效跟踪运动目标,满足实时性要求,明显优于传统的Mean Shift目标跟踪算法,减少了计算量,有助于提高其跟踪精度。     

基于边界变异的量子粒子群优化算法

将边界变异操作引入到量子粒子群优化算法中,提出基于边界变异的量子粒子群优化算法QPSOB。该算法将越界粒子随机分布在边界附近的可行域内,以增加种群的多样性、提高算法的全局搜索能力。仿真实验证明其全局收敛性能优于量子粒子群优化算法。     

基于粒子Mean Shift迁移的红外人体目标跟踪算法

提出了一种基于粒子Mean Shift迁移过程的红外人体跟踪方法.算法通过采样粒子迁移和聚类动态建立目标的状态模型和量测模型.在被跟踪区域随机布撒粒子,以各粒子对应像素的亮度作为特征值进行Mean Shift收敛性分析,使用收敛后的粒子集表达目标的当前状态;以状态粒子的坐标位置为特征值对其进行Mean Shift聚类,作为对目标的量测.连续跟踪时,下一帧的采样粒子基于上一帧的量测结果产生.与传统的基于序贯重要性采样的粒子滤波方法相比,算法不需要目标的相似性测度计算,仅用少数粒子即可实现对目标的可靠跟踪.     

基于粒子滤波的红外运动目标跟踪

提出一种基于粒子滤波及Mean Shift算法的红外运动目标跟踪方法。该方法首先利用目标区域的灰度分布,建立了一种基于统计直方图的系统观测概率模型,并针对红外目标机动性强,需要大量粒子才能保证算法鲁棒性的问题,将Mean Shift算法引入到粒子更新的过程中,使粒子分布在观测的局部区域内,在利用少量粒子实现分布多样性的同时,有效克服了粒子退化现象。序列图像的实验表明：该算法能够在目标高速运动或发生遮挡的情况下稳健跟踪目标,其总体性能优于传统的粒子滤波算法。     

基于DESO的Mean Shift目标跟踪算法研究

将基于DESO的运动预测算法和Mean Shift算法相结合,形成一种新的基于Mean Shift的快速目标跟踪算法.该算法以DESO预测位置作为Mean Shift算法下一帧候选模型的计算中心,实现了对快速运动目标的跟踪,并通过DESO对目标运动轨迹进行预测,较好地解决了目标完全遮挡时的跟踪问题.实验结果表明,该算法具有预测精度高、实时性好、抗遮挡能力强的优点.     

基于Mean Shift算法和粒子滤波器的目标跟踪

本文提出了一种综合Mean Shift算法和粒子滤波器的跟踪算法,该算法利用Mean Shift算法在重采样之后将粒子收敛到靠近目标真实状态的区域内,克服了传统粒子滤波器的退化现象并缩短了计算时间,而且算法在遮挡时能实现很好的跟踪．实验表明．算法的实时性得到了提高．     

基于DESO的Mean Shift目标跟踪算法研究

将基于DESO的运动预测算法和Mean Shift算法相结合,形成一种新的基于Mean Shift的快速目标跟踪算法.该算法以DESO预测位置作为Mean Shift算法下一帧候选模型的计算中心,实现了对快速运动目标的跟踪,并通过DESO对目标运动轨迹进行预测,较好地解决了目标完全遮挡时的跟踪问题.实验结果表明,该算法具有预测精度高,实时性好,抗遮挡能力强的优点.

     

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).