煤矿巷道顶板离层监测系统设计

针对煤矿巷道顶板离层监测的重要性,提出了一种顶板离层监测系统的设计方案;给出了该系统结构及测点布置方案,详细介绍了用于准确测量顶板离层位移量的围岩移动传感器的硬件及软件设计,并分析了顶板离层位置及顶板离层位移报警阈值的确定方法。实际测试结果表明,该系统实现了对顶板离层位移量的实时监测,测量精度达2.5%。     

基于分布式光纤技术的煤矿巷道顶板监测系统

当前巷道顶板变形监测方式为基于井下工业环网的在线实时监测,采用电子式和光纤光栅式的位移传感器并以无线方式连接,存在有较多监测盲点、误差较大、依靠连续供电等问题。针对上述问题,设计了一种基于分布式光纤技术的煤矿巷道顶板监测系统。该系统以布里渊光时域反射计(BOTDR)作为数据采集和分析的核心监测工具,采用5 mm钢绞线光纤作为感测光纤,以锚杆、锚索为固定点布设光缆,通过顶板光纤的应变变化来监测顶板变形状况,实现了对煤矿巷道顶板的实时在线分布式监测。现场应用结果表明,光纤应变变化能够实时准确地反映顶板变形情况,基于光纤应变的顶板监测结果与顶板离层仪监测结果、十字法观测结果一致。用光纤应变表征顶板变形程度消除了人为因素和断电等影响,保证了监测结果的客观性,这种长距离、耐腐蚀、抗干扰、无需供电的分布式光纤应变监测方式为煤矿提供了一种全新的巷道监测手段。     

采用SmartMesh网络的顶板离层监测系统设计

针对煤矿井下有线巷道顶板离层监测系统存在安装复杂、成本高,以及无线系统存在传感器功耗高、可靠性差、实用性不佳的问题,采用无线低功耗通信技术,开发了以Smart Mesh低功耗链状无线网络为主要通信链路的无线顶板离层监测系统。系统以磁敏角度传感器为核心部件,对顶板位移信息进行监测,并采用Smart Mesh低功耗无线自组网技术进行数据传输。通过地面中心站,实现了顶板离层数据显示、位移变化量和速度变化分析。现场应用结果证明,该系统具有实用性佳、可靠性高、传感器功耗低等特点。该系统对煤炭企业建设矿山物联网(IOT)具有重要参考价值。     

KJ132顶板离层监测系统研究与应用

为了实现井下巷道顶板离层的实时动态监测,自主研发了基于CAN总线的KJ132顶板离层监测系统。详细介绍了系统的组成与原理,并给出了该系统的煤矿上的应用效果,表明了KJ132顶板离层监测系统能准确及时的监测井下巷道顶板的运动情况。     

KJ132顶板离层监测系统的研究与应用

为了实现井下巷道顶板离层的实时动态监测,自主研发了基于CAN总线的KJ132顶板离层监测系统。详细介绍了系统的组成与原理,并给出了该系统的煤矿上的应用效果,表明了KJ132顶板离层监测系统能准确及时的监测井下巷道顶板的运动情况。     

基于FBG传感器网络的煤矿巷道在线监测系统设计

在掘进和采煤的过程中,巷道围岩的受力情况复杂多变,因此,巷道离层位移和围岩压力的实时监测是保证巷道正常工作的一个重要因素。设计了一种基于FBG传感器网络的煤矿巷道在线监测系统。该系统实现井下700 m数据采集,井上分析处理,可提供时序趋势变化、结构分布变化和阈值报警等功能。根据朱仙庄煤矿巷道的特点,系统安装4只FBG位移传感器、4只FBG土压力传感器和4只FBG温度传感器,对巷道掘进区域的离层位移、围岩压力和温度变化进行在线监测。监测结果表明:系统对离层位移、围岩压力和巷道温度变化反映灵敏,能够有效保证巷道掘进的正常进行,且为后续巷道施工提供数据支持和理论依据。     

基于ZigBee技术的煤矿巷道安全监测系统设计

针对煤矿巷道顶板安全监测采用有线网络采集数据存在布线工作繁琐、操作不方便、成本高和效率低等问题,设计了基于ZigBee技术的煤矿巷道安全监测系统。该系统通过无线应力计自动测量煤矿巷道顶板应力,利用计算机分析煤矿巷道顶板的应力应变参数,评估煤矿巷道的安全性。测试结果表明,该系统具有误差小、操作方便、成本低、效率高等优点。     

煤矿掘进巷道围岩压力在线监测预警系统

针对现有煤矿掘进工作面围岩压力监测技术难以实现有效监测、预警能力弱等问题,采用无线传感器技术,设计了一种煤矿掘进巷道围岩压力在线监测预警系统,详细介绍了系统组成、技术原理、数据传输方式、功能模块设计及预警流程。应用表明,该系统实现了对掘进巷道顶板离层、应力和声发射参数的实时监测,其多参量综合预警流程有效提高了预警的准确率。     

崔家沟煤矿巷道围岩变形规律研究

以崔家沟煤矿2209工作面回风巷为工程背景,采用"十字布点法"和顶板离层仪对巷道表面和顶板深部围岩变形进行了为期30d的现场监测。结果表明:顶底板累计移近量为142～222mm,两帮累计移近量为140～294mm,累计底鼓量为54～94mm,顶板累计离层量为44～77mm,巷道顶底板和两帮移近量、底鼓量、离层量呈递增趋势;在顶板和两帮变形大的地方底鼓较明显,深基点和浅基点范围内均发生离层;在监测前期,巷道顶底板和两帮变形处于缓慢收敛阶段,在监测后期,巷道顶底板和两帮变形处于加速收敛阶段,说明巷道已进入二次变形阶段。     

基于WSN的煤矿巷道离层监测系统的设计

针对目前煤矿巷道离层监测大多为有线监测的现状,设计了一种基于WSN的煤矿巷道离层监测系统。介绍了系统的整体架构,详细阐述了以CC2430为核心的传感器节点、以CC2430和MCP2515为核心的Sink节点的软硬件设计和工作流程。通过在兴隆庄煤矿的井下实验,测得了2.4G频率在井下的传输特性,并确定井下两个无线传感器节点的距离为15米时,可实时、可靠的监测巷道的离层情况。     

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).