基于GPRS的GPS车辆定位监控系统

详细介绍了基于GPRS的GPS车辆定位监控系统的系统组成和工作原理,该系统集成了GPS应用技术、GPRS移动通信技术、微处理器技术及传感器技术等,是目前较实用的车辆定位产品,可广泛应用于金融部门、公安部门、长途客运、货运、车辆出租等领域,提供车辆的定位、跟踪、监控、防盗防劫报警等业务。     

基于超声测距的三维精确定位系统与设计

讨论了一种新型的基于超声测距的高精度三维定位系统的原理与设计。该定位系统采用波头计数与零交叉点检测的方法来提高超声测距精度,并通过三角形方法来实现三维定位。这种三维定位系统具有精度高、成本低、易于安装、体积小、抗电磁干扰能力强、对光线不敏感、无电磁辐射等优点。     

A synoptic picture of the impact of the 26th December 2004 Indian Ocean tsunami on the coast of Sri Lanka

A numerical simulation of the 26th December 2004 Indian Ocean tsunami for the entire coast of Sri Lanka is presented. The simulation approach is based on a fully nonlinear Boussinesq tsunami propagation model and a robust coseismic source. The simulation is first confronted to available measured wave height. The agreement between observations and the predicted wave heights allowed a reasonable validation of the simulation. As a result a synoptic picture of the tsunami impact is provided over the entire coast of Sri Lanka. It is found that amplification due to shoaling applies mainly in the Eastern and Southern coast because, here, the wave is propagating across the sea floor slope, while propagating along the slope for the Western coast. Spots of high waves are due to wave focusing in some coastal areas while local submarine canyons in other areas inhibit the wave amplification.     

A high-speed 3-D image measurement method

With the recent popularization of digital cameras and projectors, practical applications of three-dimensional (3-D) image measurements based on intensity-modulation pattern projection are eagerly anticipated. Such an approach would permit a projection pattern to contain more measurement data, allowing 3-D data to be calculated with greater accuracy. However, to achieve a high level of accuracy using this approach, it is essential that an ideal observation pattern image should be obtained with a certain minimum number of stripes and a certain intensity distribution. To satisfy these requirements, an intensity correction method with two observation pattern images has previously been used. It is difficult to measure a fast-moving object in such calculations because the correspondence relation of the measured object is not established between the two photographic images, and consequently the pattern intensity is not corrected accurately. This study proposes an image analysis method for correcting intensity using an image synthesis technique that extracts precise stripes from a single observation pattern image. This analysis method allows 3-D shape measurements to be performed from a single projection pattern and a single image capture.     

嵌入式高精度GPS异地时间测量系统的设计

通过GPS授时系统实现异地时间测量的方法。利用GPS可靠性、高精度、全球覆盖等特点,辅以ARM系统高性能低成本的优势,改进并实现了基于ARM的嵌入式GPS异地时间测量系统,使异地时间测量精度和性价比明显提高。对系统存在的影响精度部分进行了分析和测试并做出相应改进,为进一步提高精度提供了理论和工程依据。     

基于定向天线WSNs的水稻田温湿度监测系统设计

针对水稻田中存在的远距离通信问题,利用定向天线通信距离远、方向性好,抗干扰能力强等优点,设计了一种适合水稻田温湿度监测的无线传感器网络(WSNs)系统。节点以MSP430F149单片机作为主控芯片,并以该节点为硬件平台编写了定向天线分簇路由协议和监控终端软件。利用该系统在水稻3个典型生长期:苗期、拔节期和抽穗期进行实验,节点天线所处高度分别为0.5,1,1.5 m,节点的最大通信距离分别为207.4,235.6,258.2 m。进行了温湿度测试实验,结果表明:该系统能够准确监测水稻田中温湿度的变化,各节点间测得的温湿度显示稳定,能够满足水稻田环境信息监测的应用要求。     

A coastal radar system for tsunami warning

A high-frequency radar system which has been used at coastal locations for measurement of surface current and wave fields is suggested and analyzed as a tsunami detection and warning system. This system would detect the presence and magnitude of a tsunami as it approaches the shore by observing the to-fro current pattern produced by the orbital velocity of the tsunami wave. For the radar system presently in existence, typical warning times exceeding 45 min are shown to be possible for Pacific United States coastal locations.     

基于立体视觉的水下三维测量系统研究

随着我国海洋战略的提出,对于海洋观测技术和装备的需求日趋迫切。针对现有水下成像系统无法实现精确三维测量这一难题,该文提出了一种基于双目立体视觉原理的水下三维测量系统研究方法,并对其可行性进行了验证。针对水下成像过程存在的水体界面折射问题,该文提出了相应的相机成像模型及系统参数标定方法,建立了防水深度达 30 m 的双目水下测量及照明装置,并在水池、近海条件下进行了实地测试。实验结果显示,在水体条件较好的情况下,系统观测距离可达 8 m 以上,有效测量距离为 0.5～4.5 m,在 0.5 m 和 4.5 m 距离处的测量误差分别为 2 mm 和 20 mm。实验验证了 水下双目成像模型、立体标定、测量模型等方法的有效性和精确性,可为水下检修作业等海洋工程行业提供一种有效的三维测量技术手段。     

基于最大似然估计的雷达高度计跟踪处理

根据Brown海面回波模型,分析了海面回波中的噪声分布特性,即功率谱分别呈指数分布的 海面回波噪声和呈均匀分布的热噪声,并对此进行了仿真研究。在此基础上对海面回波的最大似然 跟踪处理方法进行了分析,提出了基于最大似然估计的跟踪器的实现方法,介绍了其工作原理、硬 件实现方法以及主要工作指标。该跟踪器在校飞实验中获得成功,获得了大量实验数据;展示了回 波波形、跟踪轨迹等校飞数据,从这些结果上反映出该跟踪器的精确性和健壮性。     

SAR detection and characterization of sea surface slicks

In this paper we demonstrate SAR system capability for detecting and characterizing marine surface slicks. During an aircraft measurement campaign over the Gulf of Genoa (Italy), a multi-frequency SAR system, operating in P-, L- and C-bands, explored a sea area heavily covered by slicks. At the same time in situ measurements were performed with an interferential microwave probe, installed on board a small boat, capable of measuring high resolution sea spectra up to frequencies of capillary waves. By plotting SAR pixel intensity versus sea wave Bragg frequency we obtained wide portions of the sea spectrum region affected by the surface film damping. Spectra derived from SAR imagery and from gauge data present comparable slopes and furthermore the ratio between clean to slicked water spectrum obtained with the two techniques were surprisingly similar. This demonstrates the multi-frequency SAR systems ability to detect and characterize sea surface films assuming the Bragg mechanism in the radar backscatter. The outlined analysis suggests a simple methodology to monitor coastal water quality by using airborne SAR.     

Underwater bottom topography in coastal areas from TerraSAR-X data

In this article, wave refraction and shoaling in coastal areas were investigated and used to derive the bathymetry. With its high spatial resolution, which can achieve up to 1 m in SpotLight mode, and its low cut-off wavelength, the TerraSAR-X satellite provides images that are particularly suitable for the observation of wave behaviour in transient and shallow waters. By computing the two-dimensional (2D) spectra, shoaling waves were tracked from the open sea to the shoreline. The observed wave refraction and shoaling were compared with wave refraction laws and first-order wave theory (Airy theory). The retrieved bathymetry was compared against depth data from other sources such as ETOPO1, the US Coastal Relief Model and sea charts from the British Admiralty. A further aim of this article was the investigation of breaking waves showing up as near-shore image patterns. A theory is presented of how to derive the height of breaking waves by use of this pattern. Synthetic aperture radar (SAR) images with azimuth as well as range travelling waves were investigated. As test sites, we chose the entrance of Port Phillip near Melbourne (Australia) and the Duck Research Pier in North Carolina (USA).     

一种新型波高测量系统的设计

波高测量是海洋工程模型试验中的一项重要内容,为了能够准确、稳定地实时测量实验水池中的波浪,采用了一种新型的波高测量系统设计方法:首先利用液位高度与波高传感器电容量的线性关系将波高测量问题转化为电容量测量问题;其次利用波高传感器的电容量与其充放电时间的关系将波高传感器的电容量测量问题转化为充放电时间的检测问题;然后运用单片机片内模拟比较器和定时器的输入捕获功能将电容充放电时间转化为计数值;接下来将计数值通过USB接口送到上位机进行数据处理及波形显示;最后进行实验测试,实验结果表明所采用的波高测量方法是有效的,且具有线性度好、灵敏度高、精度高的优点。     

Numerical investigation of the interactions between solitary waves and pile breakwaters using BGK-based methods

The interactions between a solitary wave, which can be used to model a leading tsunami wave, and a pile breakwater made of circular cylinders are numerically investigated. We use the depth-averaged shallow water equations, which are solved by the finite volume method based on the Bhatnagar–Gross–Krook (BGK) model. The numerical results are compared with the experimental data, which yields very good agreement between them when the ratio of wave height to water depth is small (<0.25). As this ratio exceeds the value of 0.25, the larger the ratio is, the bigger deviation of numerical results from experimental data is observed, the possible reasons for this observation are discussed. Both numerical and experimental results indicate that the transmission of the solitary wave decreases and the reflection of the wave increases with reducing gaps between the adjacent cylinders, and that both transmission and reflection coefficients are not very sensitive to the variation in wave height.     

基于GSM网络分布式无线通信系统

结合滑坡监测系统,重点论述了一种基于GSM网络远程无线数据通信的实现。无线远程数据采集和监控与传统有线方式相比具有不受地理环境、气候等因素限制,具有运行成本低、系统可靠、通信范围广以及更广泛的适应性等优势,它为远程监控、远程数据采集提供了一种可行的技术手段。本文利用GSM网络短消息和拨号数据通信两大功能,实现了对滑坡体的实时监测。该无线数据通信系统可以应用于其它远程监控等中小流量数据通信系统中。     

基于北斗卫星的GPS轨迹数据异常双频定位方法

当前GPS轨迹定位方法均采用单频定位,在数据异常情况下不能保障定位精度,故此提出一种基于北斗卫星的GPS轨迹数据双频定位方法研究。先基于北斗卫星的定位原理建立用于空间几何距离测量和地面监测点精准定位的数学模型,并确定出伪距和载波相位的观测值的权重;利用北斗卫星确定出标的物的空间几何距离,及空间位置信息;由于定位系统本身及大气电离层的影响,得到空间定位信息内包含有误差项,基于北斗卫星系统可以修正GPS轨迹误差项和异常数据,实现对标的物位置信息的精准定位。测试数据表明提出定位方法的精度更高,综合定位偏差值为0.56%,同时定位误差的均值和方差控制表现更好。     

行波故障测距装置现场校验技术研究

为解决行波故障测距装置的现场检测问题,本文讨论了行波测距装置的测距原理,分析了行波测距装置内双端测距的测距方法,研究了故障行波信号特性及电流互感器及二次电缆等二次传变回路对故障行波传递的影响,探究了一套针对行波测距装置的现场校验平台和方法。检测平台主要包括基于高频线性电流放大器为基础的故障行波再现装置、电磁暂态仿真软件以及GPS卫星同步装置。高频线性电流放大器作为故障行波再现装置,至少能同时输出多路高频电流且配备GPS卫星同步系统,以及考虑了二次传变回路的基于电磁暂态仿真软件的故障模拟仿真系统。检测结果验证了现场校验方法和平台的可行性和正确性。行波测距装置现场校验能够有效发现行波测距装置的技术缺陷、检测行波测距装置测距精度及可靠性。     

Evaluations of OpenCL-written tsunami simulation on FPGA and comparison with GPU implementation

When a tsunami occurred on a sea area, prediction of its arrival time is critical for evacuating people from the coastal area. There are many problems related to tsunami to be solved for reducing negative effects of this serious disaster. Numerical modeling of tsunami wave propagation is a computationally intensive problem which needs to accelerate its calculations by parallel processing. The method of splitting tsunami (MOST) is one of the well-known numerical solvers for tsunami modeling. We have developed a tsunami propagation code based on MOST algorithm and implemented different parallel optimizations for GPU and FPGA. In the latest study, we have the best performance of OpenCL kernel which is implemented tsunami simulation on AMD Radeon 280X GPU. This paper targets on design and evaluation on FPGA using OpenCL. The performance on FPGA design generated automatically by Altera offline compiler follows the results of GPU by several kernel modifications.     

基于DSP的智能饮水机纸杯水位检测方法

为了提高传统饮水机的智能化水平,采用DSP芯片TMS320C6416作为处理核心设计了智能饮水机纸杯水位线自动检测系统,系统由摄像头、编码、处理器、阀门开关和显示模块组成.通过对放在出水口处纸杯的原始图像进行灰度化处理、边缘检测、连通域提取和噪声去除算法,分割出杯口内边缘和水位线,并根据像素点的个数计算纸杯内边缘线与水位线的距离.实验结果表明,该智能饮水机具有良好的鲁棒性,平均测量误差为0.88％,也为灌装饮料和食品的满度检测提供了思路和方法.     

Near real-time tropospheric water vapour profiling using a ground-based GPS receiver

This article presents a remote-sensing tool employing an artificial neural networks algorithm for near real-time determination of the relative humidity (RH) profile above a site using global positioning system (GPS) data recorded by a ground-based GPS receiver. GPS data were processed to obtain Integrated Water Vapour. The integrated water vapour in conjunction with ground level information for temperature, pressure, and RH was fed as inputs to the developed neural network which in turn generated the instantaneous RH profile, at six standard pressure levels of 100, 150, 200, 300, 500, and 700 hPa, as output. GPS and radiosonde data for the years 2009 and 2010 were used to train the system while the same data for 2011 were used to validate the system. The relative humidity profile results for 2011 generated using GPS data and the neural network, upon comparison with recorded in situ radiosonde RH profile measurements for the same days and times in the year 2011, had root mean square error of less than 4%, which falls within the margin of error of the Vaisala RS92 Radiosonde’s humidity measurement regime.