检索结果-南通市图书馆

A New Analysis Method for Locating the Focus and for Estimating the Size of the Focus of the backscatter Light of a LIDAR System

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Electromagnetic Analysis and Applications 2010年第3期2卷 183-188页

作者： Nianwen Cao Weiyuan Wang Yonghua Wu Fred Moshary Zhongrong Chen Jiansong Huang 不详

This paper presents a new analysis method for locating the focus and estimating the size of the focus of the backscatter light of a Lidar system. The formula for calculating the uncertainty of the location of the focus of backscatter light of a Lidar system is given, and the estimation of the size of the focus is also presented. This calculation coincides with the analysis result of ZEMAX software. By the analysis, the experiment to exactly locate the focus of the backscatter light of Lidar is carried out.

关键词： backscatter Light Focus Telescope

The Influence of IR Absorption and backscatter Radiation from CO<sub>2</sub>on Air Temperature during Heating in a Simulated Earth/Atmosphere Experiment

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Atmospheric and Climate Sciences 2020年第2期10卷 168-185页

作者： Thorstein O. Seim Borgar T. Olsen

The Greenhouse Effect was simulated in a laboratory setup, consisting of a heated ground area and two chambers, one filled with air and one filled with air or CO2. While heating the gas the temperature and IR radiation in both chambers were measured. IR radiation was produced by heating a metal plate mounted on the rear wall. Reduced IR radiation through the front window was observed when the air in the foremost chamber was exchanged with CO2. In the rear chamber, we observed increased IR radiation due to backscatter from the front chamber. Based on the Stefan Boltzmann’s law, this should increase the temperature of the air in the rear chamber by 2.4 to 4 degrees, but no such increase was found. A thermopile, made to increase the sensitivity and accuracy of the temperature measurements, showed that the temperature with CO2 increased slightly, about 0.5%.

关键词： Greenhouse Effect Radiative Forcing CO2 backscatter IR Radiation

基于backscatter的无源阵列收发技术研究

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于backscatter的无源阵列收发技术研究

作者：张开麟电子科技大学

学位级别：硕士

随着通信技术发展,广播信号、电视信号以及手机信号等无线信号无处不在。每时每刻存在的这些无线信号能量除了满足正常的通信实际上有很大一部分被浪费。如果能收集利用这些信号能量来为通信提供能量将会节省很大的能量开销。现有的无... 详细信息

随着通信技术发展,广播信号、电视信号以及手机信号等无线信号无处不在。每时每刻存在的这些无线信号能量除了满足正常的通信实际上有很大一部分被浪费。如果能收集利用这些信号能量来为通信提供能量将会节省很大的能量开销。现有的无线收发系统中由于有低噪放,功放,本振发生器等,导致系统的功耗很大,同时体积也比较大。RFID只实现了读卡器与标签之间的通信,而且其之间的通信速率很低。针对以上存在的问题,本文提出一种基于ESPAR(electronically steerable passive array radiator)的无源阵列收发技术。首先无源阵列天线收集能量来供电,同时接收空间信号来进行再调制,这种调制基于backscatter由模拟电路来实现数字调制,相比较传统的数字调制其功耗很低。本文主要对于基于backscatter的无源阵列收发技术的研究。首先本文引入一种新型的天线ESPAR来作为backscatter模拟调制的天线,相比于其他阵列天线,其功耗很低。其是通过调节有源振子与无源阵子之间的耦合来对其方向性的控制来提高天线增益。本文的另一个研究内容是基于backscatter的模拟调制,其基本原理是利用电路匹配与反射系数来实现不同的数字调制。相比于简单RFID其传输速率更大,能实现通信。在数字通信的时代模拟调制实现数字通信的方式还有待进一步研究。本文希望在已有的研究基础上能在backscatter调制技术上有所突破以期能带来一种调制方式的同时实现功耗的降低。研究内容如下:1)介绍backscatter模拟调试的特点与国内外发展现状。同时分析了基于backscatter调制的通信链路,针对其特点提出一种与ESPAR阵列相结合的通信系统。并提出了其通信链路结构。2)基于ESPAR的backscatter模拟调制的设计基础。本文介绍了模拟调制的技术原理、不同调制方式的设计要求及其实现方式,同时介绍了ESPAR的原理及实现形式。并且仿真与实际制作测试ESPAR阵列天线。3)backscatter调制收发系统设计。本文设计分别设计了ASK、4ASK、4QAM、16QAM四种模拟方式的调制。首先对于不同的调制方式先设计计算不同的星座点同时计算出其对应的模拟调制所需的对应阻抗。其次画出四种模拟调制的原理图并进行PCB设计,最后利用ADS仿真软件辅助焊接调试。测试了系统直连情况和无线情况下的ASK、4ASK、4QAM三种调制的情况,并且依据测试结果对backscatter调制系统的链路进行计算和预算。

关键词：模拟调制 backscatter ESPAR 节能

Cold Seeps Associated with Structured Benthic Communities: More Accurate Identification and Evaluation Using a New Multibeam Survey Methodology in the Offshore Southern Colombian Caribbean

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

International Journal of Geosciences 2016年第5期7卷 761-774页

作者： Adrian Digby Vladimir Puentes Jorge León Lionel Fray Associates Katy Texas USA Aquabiosfera & Anadarko PC Inc. Woodlands Texas USA Anadarko Colombia Bogota Colombia

A new methodology was developed to identify cold seeps and structured benthic communities associated, which was applied for the first time in the offshore southern Colombian Caribbean. The integral method consists on a new processing of double-coverage (200%) high-resolution backscatter data combined with bathymetric information;validation was done correlating identified gas plumes, seabed cores and drift camera surveys. Results showed that the elimination of artefacts and the increased signal of the backscatter data allowed accurate plotting of seep boundaries and categorization of seeps into an activity catalogue, with more than 200 seeps identified. Most seeps have chemosynthetic communities associated and data analysis from a previous survey showed two ridges with hard ground as the only possible areas for the development the of deep- water corals. Seep results were compared with designated Areas of Significance for Biodiversity (ASB) identifying seeps both within and outside the ASBs, and showing that the presence of seeps and chemosynthetic communities associated were driven more by geological processes than for big-scale seabed morphology, since they were found in both plains and ridges. This methodology allows an accurate seabed map of structured benthic communities, which may work as a precise geo-hazard map to ensure the oil & gas industry can avoid these areas of shallow gas for further developments, and as a map of deep-water structured benthic communities with environmental significance.

关键词： backscatter Cold Seeps Chemosynthetic Communities Southern Colombian Caribbean

Separability of Dominant Crop Cultures in Southern Germany Using TerraSAR-X Data

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Remote Sensing 2015年第2期4卷 97-107页

作者： Kuria Thiong’o René Pasternak Alfred Kleusberg Frank Thonfeld Gunter Menz Department of Geography Bonn University Bonn Germany Institute of Navigation Stuttgart University Stuttgart Germany Center for Remote Sensing of Land Surfaces Bonn University Bonn Germany

The research aims at differentiating dominant crop cultures in two test sites of Baden-Wuert- temberg, Southern Germany by creating crop signatures from radar backscatter values. It seeks to establish whether the crop signatures collected in one test site are comparable or transferable to another test site. The two test sites are located in different agro-ecological zones as described in the climate maps of the “Klimaatlas Baden-Wuerttemberg”. TerraSAR-X images (VV polarization) for the months of July and August 2010 were overlaid with crop fields’ ground truth data. As pre-processing steps, radiometric correction was carried out on the images in order to normalize the topographical effects. Classification of the crops was performed on a field scale, according to the mean and standard deviation of their backscatter values. From the results, potatoes could be uniquely differentiated from the cereals in the two different test sites for both the months of July and August 2010. Cereals (rapes, maize, barley, wheat and oats) had comparable backscatter values and their differentiation varied from one test site to another. The results’ accuracy obtained with a maximum kappa coefficient of 0.82 agrees with results of a similar research carried out in North East Germany.

关键词： TerraSAR-X Radar backscatter Crop Signatures Crop Differentiation

ROCKS & MINERALS DETERMINATION AND ANALYSIS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Abstracts of Chinese Geological Literature 2007年第4期23卷 53-60页

20072502 Cao Shuyun(State Key Laboratory of Geological Processes and Mineral Resources(GPMR),Beijing 100083,China);Liu Junlai Modern Techniques for the Analysis of Rock Microstructure:EBSD and Its Application(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,21(10),2006,p.1091-1096,18 refs.)Key words:scanning electron microscopy The application of EBSD(electron backscatter diffraction)technique has pioneered a

关键词： EBSD backscatter SHRIMP zircon isotopic silver geo

Estimation of Above Ground Biomass in Forests Using Alos Palsar Data in Kericho and Aberdare Ranges

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Open Journal of Forestry 2017年第2期7卷 79-96页

作者： Eunice Wamuyu Maina Patroba Achola Odera Mwangi James Kinyanjui Department of Geomatic Engineering and Geospatial Information Systems Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Division of Geomatics School of Architecture Planning and Geomatics University of Cape Town Cape Town South Africa Department of Forestry School of Natural Resources and Environmental Studies Karatina University Karatina Kenya

Above Ground Biomass is one of the six pools identified in the inventory of forest resources and estimation of greenhouse gas emissions and sinks from the forestry sector. The pool varies by management practices in different agro-ecological or agro-climatic zones in forests. The quantification of above ground biomass (AGB) hence carbon sequestration in forests has been very difficult due to the immense costs required. This research was done to estimate AGB using ALOS PALSAR L band data (HH, HV polarisation) acquired in 2009 in relation with ground measurements data in Kericho and Aberdares ranges in Kenya. Tree data information was obtained from ground measurement of DBH and tree heights in 100 circular plots of 15 m radius, by use of random sampling technique. ALOS PALSAR image is advantageous for its active microwave sensor using L-band frequency to achieve cloud free imageries, and the ability of long wavelength cross-polarization to estimate AGB accurately for tropical forests. The variations result between Natural and plantation forest for measured and estimated biomass in Kericho HV band regression value was 0.880 and HH band was 0.520. In Aberdare ranges HV regression value of 0.708 and HH band regression value of 0.511 for measured and estimated biomass respectively. The variations can be explained by the influence of different management regimes induced human disturbances, forest stand age, density, species composition, and trees diameter distribution. However, further research is required to investigate how strong these factors affect relationship between AGB and Alos Palsar backscatters.

关键词： Above Ground Biomass Estimation Green House Gas Carbon Credits Alos Palsar backscatter Cross-Polarization Regression Analysis

Effect of surface roughness on the measurement of high power laser with a cone-shaped cavity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Effect of surface roughness on the measurement of high power...