ZigBee无线传感器网络在瓦斯监控系统中的应用

为了提高煤矿瓦斯监控系统的安全性和稳定性,采用符合ZigBee技术的芯片CC2430,设计了煤矿瓦斯监控系统.该系统采用典型的无线传感器网络结构,以基于分簇的能量控制路由算法,降低了网络系统的能耗,延长了网络使用寿命.分析表明,ZigBee技术在煤矿瓦斯监控系统中应用,可有效地减少煤矿安全事故的发生,降低井下人员的伤亡,保证系统传递信息的实时性和有效性.     

Zigbee网络应用在煤矿井下环境的技术优势

现代煤矿企业对于信息自动化的要求越来越高,很多技术集中的生产场所都要求实现无人化的智能管理。建设井下大范围环境监测监控和人员监测监控系统,可以减少下井人员数量,降低井下人员工作强度,并做到精确监控与有效管理。现有的井下监控系统对传感器以及设备信息的采集主要依靠硬接线,存在着布线工作量巨大而且复杂,维护困难的缺点。近年来无线通讯技术陆续用于部分井下系统,而针对井下生产设备监控和环境安全监控的无线监控系统基本处于试验阶段。ZigBee作为一种新兴的近距离、低复杂度、低功耗、低数据速率、低成本的无线网络技术,相对其他无线传输技术更适合煤矿井下环境。本文将从技术原理、传输速度、传输距离以及功耗等方面论证其优势。     

基于Zigbee的井下人员定位考勤系统的设计

本文基于ZigBee技术,设计了煤矿井下人员定位考勤系统,实时对井下人员进行定位、身份识别。实现了井下人员的考勤统计,并为监控井下的人员分布提供了依据,适用于煤矿井下的安全管理。     

煤矿井下Zigbee网络技术研究

文章开展了Zigbee技术在矿井井下应用时工作对象分析、产品性能选取的工程实践工作,力求在现有Zigbee产品以及通用的工业控制产品的基础上合理选择设备参数,满足井下监测系统要求.文章分析了矿井井下监控应用的需求,确定了井下ZigBee监控网络的构成方案;并分析了井下环境因素(如巷道的形状和走向、井下粉尘及湿气等)对ZigBee无线传输的影响以及监控数据量的需求,在此基础上确定了井下无线监控网络的主要技术参数以及节点设备构成.     

基于组态的煤矿安全监控系统的研究

我国矿井分布广阔、地质条件复杂,煤矿的安全生产与井下工作人员的人身安全息息相关。因此,煤矿事故的多发成了煤炭开采中的最大隐患经过研究发现对煤矿开采中的井下环境状况实时监控,可以有效地降低事故的发生率．本文采用组态软件作为上位机对煤矿生产过程中的可能诱发煤矿事故的几项致灾因素进行监测,通过实时刷新使得监测人员掌握井下的安全生产状况,最终达到降低煤矿开采的事故率、     

基于ZigBee技术的井下人员定位安全监测系统

采用德州仪器(TI)公司CC2431芯片,构建了基于ZigBee协议的井下人员定位及安全监控系统.网络由网络协调器、定位参考基站、人员终端组成,通过在井下建立线状和网状ZigBee无线网络,实现井下人员定位、环境监测和通信等功能.通过人员终端测定附近定位基站的信号强度,可以用监控系统上位机软件实时观测井下人员的活动,并进行数据采集和传输.通过对天线的近场效应进行补偿性修正,定位误差降低了约50%.模拟井下环境的性能测试结果表明,该系统可以达到0.25 m的测量分辨率,定位误差小于2 m,可以支持4 kbps的数据传输,满足井下人员定位和事故发生时的疏散调度要求.     

ZigBee技术在煤矿井下通信系统中的应用

ZigBee是一种成熟的无线通信技术。本文介绍ZigBee技术特点,协议模型及应用,并以该技术为基础,设计了一种应用于煤矿井下的无线通信系统。     

矿井下ZigBee的Mesh网络安全监控系统设计

针对煤矿井下安全监控的需求,通过方案和系统设计、NS仿真分析,开发了一种基于ZigBee技术与Mesh网络相结合的安全监控系统。该系统通过安装在终端节点上的传感器采集井下数据,将采集到的数据通过Mesh网络传输到井上监控中心,实现对井下环境数据的实时监控。该系统具有可靠性高、网络覆盖范围大、移动性好的特点。对煤矿井下安全监控及安全事故的预防具有指导意义。     

井下瓦斯浓度监测机器人控制系统的设计

针对煤矿瓦斯爆炸事故问题,本文将ZigBee无线传感技术与履带式机器人探测技术相结合,研究了一种具有独立越障、避障能力的井下瓦斯浓度监测机器人。机器人以S3C2440为核心控制单元,结合CC2430射频芯片,在嵌入式系统Linux下控制机器人,快速准确地探测井下瓦斯浓度并及时想地上监控中心传送数据,一旦监测到井下有瓦斯异常情况,可及时发出警报,能够较好的完成井下瓦斯爆炸事故的预测和报警工作,对保障工人安全具有重要的现实意义。     

基于ZigBee技术的矿井安全监控系统

针对煤矿复杂的工作环境及安全生产的要求,提出一种基于ZigBee技术的矿井安全监控系统.首先介绍了ZigBee技术的特点,重点对井下数据采集子系统进行了设计,其中主要包括井下人员携带的ZigBee终端移动节点、ZigBee路由器以及ZigBee协调器的设计,并通过CAN总线将采集的数据传送到地面监控中心,最后给出了井上...     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to