NTFS文件系统剖析

针对Windows操作系统所使用的NTFS与FAT文件系统的簇、容量、安全、字符集等,分析了两种文件系统的区别与优缺点.分析了NTFS文件系统使用的数据结构,特别针对其主控文件表MFT、MFT记录、文件结构、目录结构进行了深入的剖析,给出了NTFS文件系统中文件与目录的MFT记录结构.     

基于MapReduce的增量数据挖掘研究

频繁项集挖掘是数据挖掘过程中的重要部分,传统数据挖掘算法中常用Apriori算法和FP增长算法来挖掘频繁项集。在实际应用中,传统算法往往不能用于频繁更新的数据库,采用IMBT数据结构能从不断更新的数据库中挖掘频繁项集,但是这将导致存储空间不足和运行效率低下的问题。基于MapReduce的增量数据挖掘能够有效解决这些问题,通过对比基于MapReduce的增量数据挖掘和传统增量数据挖掘的运行时间可以证明,基于Mapeduce的增量数据挖掘更高效。     

基于JTAG接口的YAFFS文件系统

基于JTAG接口实现YAFFS文件系统是一种崭新的设计思路。以MTD子系统的结构为基础,抽象出MTD设备层,专注于MTD芯片驱动程序的设计,给上层YAFFS文件系统提供了统一的操作接口。在此基础上实现的基于JTAG接口的MTD驱动程序结构,不仅支持C＊Core平台和YAFFS文件系统,而且经过简单移植可以扩充到ARM等平台和FAT等文件系统,具有非常好的开放性和适应性。     

Linux虚拟文件系统分析

首先简要地介绍Linux系统中虚拟文件系统（VFS）的分层抽象,然后详细分析VFS通用模型中的四个对象类型及内核中实现它们的数据结构,最后介绍它们之间是如何联系起来的。通过对其分析,使读者加深对VFS系统的理解。     

ZFS文件系统Snapshot技术的分析

快照是一种重要的存储数据的技术,可以在不停止应用程序的情况下对数据进行备份。本文对Solaris平台下的ZFS文件系统中的快照技术进行了分析,介绍了快照的工作原理、实现技术及数据结构,并在ZFS中进行快照创建、数据恢复的实例分析,结果表明ZFS文件系统中的快照技术能避免数据的丢失,可以有效地保护该系统下的数据,并且在操作系统的实验教学中对文件系统的分析具有较大的实践意义。     

使用冗余数据设计树型关系的数据结构

关系数据库设计时要遵守设计范式,要尽可能减少数据的冗余度,以使结构更合理,消除存储异常。但在具体的数据库设计实践中采用恰当的范式等级,适当的使用冗余数据,可以达到更好的使用效果。本文通过示例介绍了数据库设计案例中的树型关系的数据结构的设计,说明数据库设计中正确使用冗余数据的好处。     

多处理机环境下UNIX文件系统的设计和实现

本文论述了在多处理机环境下UNIX 文件系统的设计和实现,以保证文件系统运行的正确性和极大限度地开发信息处理的并发性。文中提出多处理机UNIX 文件系统的模型、结构及特点。着重论述多处理机UNIX 文件系统主要数据结构低层缓冲区和内部其他数据结构的组织和管理。最后论述了多处理机环境中出现的数据一致性问题。     

Linux虚拟文件系统实现技术探讨

文章论述了Linux文件系统的逻辑关系和逻辑结构，对VFS中几个主要的数据结构进行了分析，剖析了Linux文件系统中一个物理文件系统的安装与注册、VFS的产生，以及通过VFS管理和访问物理文件系统的内核工作机制。     

Linux操作系统的文件系统建立过程的研究

Linux文件系统的建立过程包括文件系统的注册和安装。该文深入研究了Linux文件系统的注册和注销、安装和卸载过程,并详细分析了整个过程中采用的数据结构,以及文件系统建立的整体结构。     

NTFS文件系统的主要数据结构

文章分析了NTFS文件系统的主要数据结构。从编写直接操作NTFS文件系统程序所需的知识出发,给出了NTFS文件系统中主要的数据结构,并对数据结构中的主要成员给出了详细的说明。     

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).