浅海水听器的研究

浅海水听器是一种利用压电敏感元件接受地质信号将机械震动转换为电信号的机电装置,是应用于海洋地震勘探以及工程测量领域的专用传感器.浅海水听器作为海洋地震勘探的关键设备之一,其性能直接关系到地震数据采集的质量.因此,浅海水听器的技术和应用一直倍受广大物探工作者的关注.目前.勘探市场上的水听器灵敏度普遍偏低,在某种程度上制约着勘探中微弱地震信号的数据采集.介绍了一种采用四块圃片状压电陶瓷敏感元件配接变压器的浅海水听器,研究了该浅海水听器的结构和等效电路.在相同条件下,通过与圆筒状水听器和配接前置放大器的水听器的比较分析,表明了采用此种结构的水听器在灵敏度上的优越性,提高了地震数据采集质量,以满足现代海洋勘探技术要求.     

基于VxWorks的CPCI多通道卡驱动设计与实现

为解决大规模海上拖缆地震勘探对控制系统的实时性和处理效率问题，提出了采用CPCI工控机箱为硬件平台，VxWorks实时操作系统为软件处理平台，设计和实现了一套CPCI多通道卡驱动程序。通过分析VxWorks驱动程序结构和CPCI总线设备特点，重点给出了从内存映射模块、中断注册初始化模块和中断处理模块等方面进行CPCI多通道卡驱动程序的设计方法、实现过程和关键代码。集成CPCI多通道卡驱动程序的“海燕”拖缆定位与控制系统具备12个通道数据处理能力，多次成功应用到海上生产作业中，其实时性和处理效率满足大规模海上拖缆地震勘探对控制系统的要求。CPCI多通道卡驱动程序设计合理，易于扩展到其他具有多通道、多任务、实时性要求高的嵌入式数据采集系统中。     

一种MEMS同振柱型仿生矢量水听器的研制

提出了一种结合MEMS技术、仿生原理和压阻原理的同振柱型矢量水听器,即由二维仿生水听器和声压水听器组合而成的柱体。在声学理论基础上详细介绍了该水听器的封装设计及制作过程,在国防水声一级计量站对该矢量水听器进行校准实验,实验结果表明:该同振型矢量水听器的工作频带范围为0～3 kHz;X通道灵敏度-177.9 dB(2 kHz),Y通道灵敏度-175.4 dB(2 kHz),声压通道灵敏度-175.8 dB(2 kHz);具有很好的"8"字指向性;可承受3 MPa压力。此新型MEMS同振矢量水听器适用于民用船只避障,渔业捕捞,海洋勘探等领域。     

用于海洋地震勘探系统的数据变采样率采集及自检控制模块

针对传统海洋地震勘探系统的不足之处,本文提出了一种用于海洋地震勘探系统的数据变采样率采集及自检控制模块。该模块采用一种基于锁相环的变采样率采集节点同步设计方法,实现了采样率可调节的数据采集功能,同时,该模块还实现了基于奇、偶通道控制模块的自检功能,完成了变道数采集以及系统自检测。试验现场的测试结果表明,系统的同步精度为4.86 ns,可灵活实现海洋地震勘探系统4 ksample/s（sample per second,每秒采样次数）、2 ksample/s、1 ksample/s、500 sample/s、250 sample/s 5种采样率可调的功能,同时能够进行包括奇、偶通道串扰,通道一致性,谐波失真,噪声、直流偏置六项系统自检功能,从而验证了本文所提出的海洋地震勘探系统的可行性。     

提高光栅数字地震检波器精度的方法研究

在地震勘探系统中,随着数据记录系统动态范围的突破,地震检波器的动态范围已不能满足系统的要求,提高检波器的精度和动态范围变成地震勘探技术研究的关键.光栅数字地震检波器的研制成功,提高了检波器的精度和动态范围.通过对光栅传感器机理的深入分析,采用5细分专用芯片为核心的细分电路,成功实现了光栅脉冲信号的20倍细分技术.在采用100线计量光栅的情况下,使检波器分辨率达到0.000 5 mm,动态范围达到75dB.并采用PIC单片机系统完成了振动信号的再现.该方法将有助于光栅数字地震检波器的性能完善,为实现高精度地震勘探技术奠定基础.     

基于强化Q学习的海上地震勘探航线自动规划方法

海上地震勘探航线规划作为综合导航系统的重要组成部分，一直是各家石油公司的研究重点。由于海上地震勘探的特殊作业环境，除洋流、障碍物、水下环境和渔业等因素的干扰外，拖缆作业实际施工效率较低，直接导致工区采集成本的增加。提出一种基于强化Q学习的海上地震勘探航线自动规划方法，以工区前绘测线为研究对象，自动规划拖缆船航行线路，减少人为因素干扰，提高拖缆作业的工作效率，有利于海上油气田勘探效益最大化和可持续发展。     

基于MPC8270的处理器板卡设计

随着海洋地震勘探发展,为了实现海洋地震勘探采集数据的实时传输和处理,设计了一种基于MPC8270的地震数据采集处理板卡;根据海洋地震数据采集处理的实时性和大数据量要求以及MPC8270处理器的特性,设计了基于MPC8270和FPGA的CPCI总线通信结构,能够实现地震数据的高速实时传输;详细介绍了MPC8270的关键外围电路、FPGA及CPCI总线电路的硬件设计及实现方法,并在实际应用中给出了板卡嵌入式操作系统VxWorks配置的实现方式;板卡以MPC8270作为核心处理器,以FPGA为控制核心电路,以VxWorks为实时操作系统,实现地震数据的高速处理和CPCI总线实时传输功能;经过多次实验室内部测试及海上实际生产应用,结果表明地震数据采集处理板卡能够实现地震数据的高速处理和实时传输,并且板卡性能稳定可靠;板卡的设计简单,结构通用,对数据处理、总线控制和信息交换等领域相关系统的开发具有一定的参考价值。     

地震多属性分析系统的面向对象设计及敏捷开发过程

地震多属性分析(Seis2A)系统采用现代数学、信息学工具,实现了多种地震属性提取分析方法,是用于高精度地震勘探和油藏描述的自主研发软件.基于面向对象的设计分析方法,介绍了需求分析、系统框架设计,类详细设计和C++/Qt/Coin3D代码实现的全过程.项目管理采用敏捷开发过程,进行了以人为中心、结对编程、快速原型、单元测试、代码重构、多次迭代、持续集成、小型团队的开发实践.     

基于MEMS仿生矢量水听器的水声定向研究

MEMS矢量水听器不仅可以测量声压信号,还可以测量质点的振速信号,它具有与频率无关的偶极子自然指向性.单一的矢量水听器就能够测量水中的声压和质点振速.利用矢量水听器的这种特性,结合波束形成原理,采用数字信号处理(DSP)技术,设计了基于MEMS仿生矢量水听器的水声定向系统,并进行了实际测试,结果表明:该系统能很好地实现对目标360°方位的定向功能.     

基于数字水听器的分布式水下声场测量系统

设计了一种自容式数字水听器分布式水声测量系统。海洋声学测量系统由多个数字水听器连接构成,各个数字水听器通过电缆逐个相连,可以调整阵元的间隔和阵元个数。数字水听器可对采集获得的数据进行自容式存储或实时上传,优化设计了可高速串行数据传输的RS-485总线,采用8B/10B链路编码,利用串行信号的上升/下降的时钟边沿作为高速时钟采样的起始标志,实现了数据帧的提取,可实现串行编码数据沿双绞线以15MB/s远距离传输,并在总线上参考IEEE1588授时协议给出了一种基元同步方案,同步最大误差为0.5μs。最终通过海上试验证明:采集效果良好,系统工作可靠、整体功耗低,各个阵元同步准确,可以广泛应用于水下阵元测量领域。     

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).