关于雷达技术的论文英文版怎么写
关于雷达技术的论文英文版怎么写
地质雷达在水利工程质量检测中的应用1 前言 地质雷达作为近十余年来发展起来的地球物理高新技术方法,以其分辨率高、定位准确、快速经济、灵活方便、剖面直观、实时图象显示等优点,备受广大工程技术人员的青睐。现已成功地应用于岩土工程勘察、工程质量无损检测、水文地质调查、矿产资源研究、生态环境检测、城市地下管网普查、文物及考古探测等众多领域,取得了显著的探测效果和社会经济效益,并在工程实践中不断完善和提高,必将在工程探测领域发挥着愈来愈重要的作用。而地质雷达技术用于堤防隐患的探测尚属初步阶段,通过广大物探技术人员的共同努力,达到了解和掌握不同隐患类型在雷达图像上的反映特征,在不断总结探测经验的基础上,提高异常的判断能力和精度,较确切地推定堤防工程隐患的性质和位置,以便指导有关管理单位加强堤防工程重点部位的维护和防范,提高和巩固堤防工程的运行周期和防洪能力。本文以永定河堤防工程护砌质量检测为实例,说明地质雷达技术在堤防工程探测中的应用情况,以此与同行进行切磋,推动堤防工程探测技术的发展,不妥之处,敬请批评指正。2 基本原理地质雷达与探空雷达相似,利用高频电磁波(主频为数十数百乃至数千兆赫)以宽频带短脉冲的形式,由地面通过发射天线(T)向地下发射,当它遇到地下地质体或介质分界面时发生反射,并返回地面,被放置在地表的接收天线(R)接收,并由主机记录下来,形成雷达剖面图。由于电磁波在介质中传播时,其路径、电磁波场强度以及波形将随所通过介质的电磁特性及其几何形态而发生变化。因此,根据接收到的电磁波特征,既波的旅行时间(亦称双程走时)、幅度、频率和波形等,通过雷达图像的处理和分析,可确定地下界面或目标体的空间位置或结构特征。雷达波(电磁波)在界面上的反射和透射遵循Snell定律。实际观测时,由于发射天线与接收天线的距离很近,所以其电磁场方向通常垂直于入射平面,并近似看作法向入射,反射脉冲信号的强度,与界面的反射系数和穿透介质的衰减系数有关,主要取决于周围介质与反射目的体的电导率和介电常数,对于以位移电流为主的介质,既大多数岩石介质属非磁性、非导电介质,常常满足σ/ωε<<1,于是衰减系数(β)的近似值为:既衰减系数与电导率(σ)及磁导率(μ)的平方根成正比,与介电常数(ε)的平方根成反比。而界面的反射系数为:式中Z为波阻抗,其表达式为:显然,电磁波在地层中的波阻抗值取决于地层特性参数和电磁波的频率。由此可见,电磁波的频率(ω=2πf)越高,波阻抗越大。对于雷达波常用频率范围(25~1000MHz),一般认为σ<<ωε,因而反射系数r可简写成:上式表明反射系数r主要取决于上下层介电常数差异。应用雷达记录的双程反射时间可以求得目的层的深度H:式中:t为目的层雷达波的反射时间;c为雷达波在真空中的传播速度(3m/ns);εr为目的层以上介质相对介电常数均值。3 工程概况北京市界内永定河左、右堤防于清朝乾隆年间修筑,后经数次维修和加固形成现有规模,主体为梯形,顶宽约10m,可见堤高约5~6m,堤内坡坡度为1:5~1:0,外坡相对较缓为1: 0~1: 5。堤身为人工堆积,主要由粉细砂(中下游段)、卵砾石(上游段)组成。介质构成复杂多变,分布不均,且处于包气带中,极为干燥。堤基为第四系全新统地层,岩性以粉细砂为主,下游段出现黑色淤泥质粘土夹层,层厚约7~0m。地下水位埋深(自地表计):卢沟桥附近约0m,至下游逐渐变浅,达省/市界附近(石佛寺)一带约0m。永定河卢沟桥下游至省/市界左、右堤防共划定险工段12处23段,分布在左堤约60Km和右堤约30Km范围内,其险工段内坡为浆砌石(厚约40cm——原设计标准)结合铅丝石笼构成的护砌,并于1964~1989年间营建,浆砌石护坡除可见堤身部分露出外,其余部分与铅丝石笼水平护底均埋于河滩滩地以下,一般为0~0m,外铺0m的铅丝石笼护底。这些险工段在历史上均有决口或抢险加固的记载。为满足北京市对永定河防洪设计的需要,保证该堤防渡汛万无一失,故进行地球物理勘探工作,以检测堤防工程的护砌质量,便于99年6月份之前进行加固处理。4 测试技术及资料处理为判断险工段堤内坡护险浆砌石质量的优劣,沿内坡坡脚布置一条雷达探测剖面,并按其走向连续测试。外业施测使用瑞典MALA地质仪器有限公司生产的RAMAC/GPR地质雷达系统,天线的中心频率为250MHz,收发天线的间距为6m。实测采用剖面法,且收发天线方向与测线方向平行。记录点距为2m,采样频率为3893MHz,单一记录迹线的采样点数为512,迭加次数为16,记录时窗为180ns,若取堤身土体的雷达波速为08~10m/ns,表层浆砌石的雷达波速为10~12m/ns,综合考虑该地层剖面特征,选取雷达波速中值为10m/ns,则此时该雷达系统的最小纵向分辨率为8~10cm。雷达资料的数据处理与地震反射法勘探数据处理基本相同,主要有:①滤波及时频变换处理;②自动时变增益或控制增益处理;③多次重复测量平均处理;④速度分析及雷达合成处理等,旨在优化数据资料,突出目的体、最大限度地减少外界干扰,为进一步解释提供清晰可辨的图像。处理后的雷达剖面图和地震反射的时间剖面图相似,可依据该图进行地质解释。5 成果分析地质雷达资料的地质解释是地质雷达探测的目的。由数据处理后的雷达图像,全面客观地分析各种雷达波组的特征(如波形、频率、强度等),尤其是反射波的波形及强度特征,通过同相轴的追踪,确定波组的地质意义,构制地质——地球物理解释模型,依据剖面解释获得整个测区的最终成果图。地质雷达资料反映的是地下地层的电磁特性(介电常数及电导率)的分布情况,要把地下介质的电磁特性分布转化为地质分布,必须把地质、钻探、地质雷达这三个方面的资料有机结合起来,建立测区的地质——地球物理模型,才能获得正确的地下地质结构模式。雷达资料的地质解释步骤一般为:⑴ 反射层拾取根据勘探孔与雷达图像的对比分析,建立各种地层的反射波组特征,而识别反射波组的标志为同相性、相似性与波形特征等。⑵ 时间剖面的解释在充分掌握区域地质资料,了解测区所处的地质结构背景的基础上,研究重要波组的特征及其相互关系,掌握重要波组的地质结构特征,其中要重点研究特征波的同相轴的变化趋势。特征波是指强振幅、能长距离连续追踪、波形稳定的反射波。同时还应分析时间剖面上的常见特殊波(如绕射波和断面波等),解释同相轴不连续带的原因等。下部架空时的图像,该剖面第三反射同相轴自剖面点4m处断开,形成“背斜”状的强反射层,此现象延续到剖面点8m处,此段浆砌石与下部土体分离导致架空,其范围与已知情况吻合。 通过雷达测试成果的地质解释共圈定出73处浆砌石存在不同程度的隐患或质量较差,这些隐患的类型一般为:①浆砌石厚度较薄;②浆砌石与下部土体分离形成架空;③浆砌石胶结不良或松散;④浆砌石出现裂缝等不良现象。 护砌整体质量较差的堤段多为年久失修严重,浆砌石与下部堤身土体接触差,多形成架(悬)空状态,造成护砌断裂、塌陷等不良现象较普遍,且多具一定规模。而造成上述现象存在的原因,笔者分析后认为浆砌石面存在许多缝隙,且砂浆质量差、少浆,下部又无防渗护层,堤身土体多由粉细砂组成,经降水入渗,粉细砂局部被冲刷淘失,在砌石与堤身土体之间形成空洞,并有继续扩大发展之趋势。该物探成果经开挖验证(见图4——开挖照片),完全符合客观实际,受到了甲方的赞誉。6 结语地质雷达以其高效快速、高精度在护险工程探测中能够发挥重要作用,取得了良好的应用效果,且对浅层或超浅层的工程探测中有着十分广阔的应用前景,然而地质雷达的探测深度和精度与所采用的天线频率有很大关系,天线的频率越低探测深度越大,则精度越低;而天线的频率越高,探测深度越浅,则精度越高。本次采用中心频率250MHz的天线进仅供参考,请自借鉴。希望对您有帮助。
稀疏成份分析及在雷达成像处理中的应用稀疏成份分析是一种新兴的信号分析方法。它以过完备词典为基础,能从有限的观测数据中获得信号的稀疏表示,有效地挖掘信号的自然属性和本质的驱动源,提高变换域的分辨率,为信号处理提供了有力的工具。作为信号处理的重要组成部分,雷达成像技术无论在军事还是民用上都有巨大的应用潜力。雷达成像本质上就是一个信号表示过程,由于高频区雷达目标散射行为具有局部特性,用稀疏成份分析方法能提高雷达图像的质量,有利于图像分析和目标识别。针对雷达成像的应用背景,本文研究了稀疏成份分析中稀疏性度量函数构造的一般准则等理论问题,以及基于稀疏成份分析的雷达成像算法,包括一维距离像、二维逆合成孔径雷达成像和多频段雷达信号综合技术等。研究了稀疏成份分析中度量函数的构造和算法分析等理论问题。利用稀疏成份分析方法研究了高分辨一维距离像稀疏表示的原子构造与相关算法,并对算法的参数估计性能进行了理论分析。研究了基于稀疏成份分析的逆合成孔径雷达成像算法。根据雷达目标散射信号的稀疏表示模型,研究了多频段多分辨雷达信号综合技术。根据雷达目标的理想点散射体模型和几何绕射模型,分析了多频段雷达回波观测信号的联系与差别,并利用稀疏成份分析方法提出了高分辨一维距离像的多频段信号综合成像技术。针对多频段窄带组网雷达检测海上目标的应用背景,根据雷达目标在低分辨回波中的稀疏分布特性和海杂波的分布特性,提出了多雷达距离分辨率匹配处理技术,提高了雷达回波的距离分辨率并实现了多雷达距离分辨率的匹配统一,为多频段窄带雷达信号综合提供了统一的基础。
田雨的作业都跑到这里来了……
关于雷达技术的论文英文版
About RadarThe concept of radar formed in the early 20th century, before and after the Second World War was the rapid The principle of radar, the device is a transmitter antenna through the electromagnetic energy of a shooting at the direction of the space, in the direction of objects encountered reflection of electromagnetic waves; radar antenna to receive the reflected waves, to the receiving equipment to carry out processing, extraction The object was related to some of the information (the target objects to the distance between radar, or the rate of change from the radial velocity, location, height, ) CW radar and radar is divided into two major categories of radar Radar pulse as a result of easy to achieve precise location and receive echo in the resting pulse during the launch, the receiving antennas and antenna can be used to launch the same deputy antennas, and therefore in the development of radar in the main UN Measuring the distance is a measure of the actual launch with the pulse-echo pulse of the time difference between, as a result of electromagnetic waves in order to spread the speed of light, which can be converted into the precise distance from the The goal is to position the antenna to use sharp beam position Elevation on the narrow beam angle of elevation According to the elevation and distance will be able to calculate the target When the radar and the relative motion between the target, the radar echoes received by the target frequency radar and launch a different frequency, known as the difference between the Doppler From the Doppler frequency can be extracted from the main message is one of the radar and the distance between the target rate of When the goal of interference with the clutter at the same time present in the same spatial resolution of the radar unit, among them the use of Doppler radar frequency interference from the different clutter in the detection and tracking the Radar has the advantage of both day and night to detect long-range goals, and not subject to fog, cloud and rain to stop, with all-weather, all the characteristics and a certain degree of As a result, it has become not only essential military electronic equipment, and is widely used in socio-economic development (such as weather forecasting, resource exploration, environmental monitoring, ) and scientific research (study of celestial bodies, atmospheric physics, ionospheric structure, ) And on-board airborne synthetic aperture radar remote sensing has become a very important The spatial resolution of up to a few tens of meters, and has nothing to do with Radar in the flood monitoring, sea ice monitoring, soil moisture survey of forest resources inventory, such as the Geological Survey shows a very good application 用翻译机翻得。你改一下明显的错误,很快可以搞定
地质雷达在水利工程质量检测中的应用1 前言 地质雷达作为近十余年来发展起来的地球物理高新技术方法,以其分辨率高、定位准确、快速经济、灵活方便、剖面直观、实时图象显示等优点,备受广大工程技术人员的青睐。现已成功地应用于岩土工程勘察、工程质量无损检测、水文地质调查、矿产资源研究、生态环境检测、城市地下管网普查、文物及考古探测等众多领域,取得了显著的探测效果和社会经济效益,并在工程实践中不断完善和提高,必将在工程探测领域发挥着愈来愈重要的作用。而地质雷达技术用于堤防隐患的探测尚属初步阶段,通过广大物探技术人员的共同努力,达到了解和掌握不同隐患类型在雷达图像上的反映特征,在不断总结探测经验的基础上,提高异常的判断能力和精度,较确切地推定堤防工程隐患的性质和位置,以便指导有关管理单位加强堤防工程重点部位的维护和防范,提高和巩固堤防工程的运行周期和防洪能力。本文以永定河堤防工程护砌质量检测为实例,说明地质雷达技术在堤防工程探测中的应用情况,以此与同行进行切磋,推动堤防工程探测技术的发展,不妥之处,敬请批评指正。2 基本原理地质雷达与探空雷达相似,利用高频电磁波(主频为数十数百乃至数千兆赫)以宽频带短脉冲的形式,由地面通过发射天线(T)向地下发射,当它遇到地下地质体或介质分界面时发生反射,并返回地面,被放置在地表的接收天线(R)接收,并由主机记录下来,形成雷达剖面图。由于电磁波在介质中传播时,其路径、电磁波场强度以及波形将随所通过介质的电磁特性及其几何形态而发生变化。因此,根据接收到的电磁波特征,既波的旅行时间(亦称双程走时)、幅度、频率和波形等,通过雷达图像的处理和分析,可确定地下界面或目标体的空间位置或结构特征。雷达波(电磁波)在界面上的反射和透射遵循Snell定律。实际观测时,由于发射天线与接收天线的距离很近,所以其电磁场方向通常垂直于入射平面,并近似看作法向入射,反射脉冲信号的强度,与界面的反射系数和穿透介质的衰减系数有关,主要取决于周围介质与反射目的体的电导率和介电常数,对于以位移电流为主的介质,既大多数岩石介质属非磁性、非导电介质,常常满足σ/ωε<<1,于是衰减系数(β)的近似值为:既衰减系数与电导率(σ)及磁导率(μ)的平方根成正比,与介电常数(ε)的平方根成反比。而界面的反射系数为:式中Z为波阻抗,其表达式为:显然,电磁波在地层中的波阻抗值取决于地层特性参数和电磁波的频率。由此可见,电磁波的频率(ω=2πf)越高,波阻抗越大。对于雷达波常用频率范围(25~1000MHz),一般认为σ<<ωε,因而反射系数r可简写成:上式表明反射系数r主要取决于上下层介电常数差异。应用雷达记录的双程反射时间可以求得目的层的深度H:式中:t为目的层雷达波的反射时间;c为雷达波在真空中的传播速度(3m/ns);εr为目的层以上介质相对介电常数均值。3 工程概况北京市界内永定河左、右堤防于清朝乾隆年间修筑,后经数次维修和加固形成现有规模,主体为梯形,顶宽约10m,可见堤高约5~6m,堤内坡坡度为1:5~1:0,外坡相对较缓为1: 0~1: 5。堤身为人工堆积,主要由粉细砂(中下游段)、卵砾石(上游段)组成。介质构成复杂多变,分布不均,且处于包气带中,极为干燥。堤基为第四系全新统地层,岩性以粉细砂为主,下游段出现黑色淤泥质粘土夹层,层厚约7~0m。地下水位埋深(自地表计):卢沟桥附近约0m,至下游逐渐变浅,达省/市界附近(石佛寺)一带约0m。永定河卢沟桥下游至省/市界左、右堤防共划定险工段12处23段,分布在左堤约60Km和右堤约30Km范围内,其险工段内坡为浆砌石(厚约40cm——原设计标准)结合铅丝石笼构成的护砌,并于1964~1989年间营建,浆砌石护坡除可见堤身部分露出外,其余部分与铅丝石笼水平护底均埋于河滩滩地以下,一般为0~0m,外铺0m的铅丝石笼护底。这些险工段在历史上均有决口或抢险加固的记载。为满足北京市对永定河防洪设计的需要,保证该堤防渡汛万无一失,故进行地球物理勘探工作,以检测堤防工程的护砌质量,便于99年6月份之前进行加固处理。4 测试技术及资料处理为判断险工段堤内坡护险浆砌石质量的优劣,沿内坡坡脚布置一条雷达探测剖面,并按其走向连续测试。外业施测使用瑞典MALA地质仪器有限公司生产的RAMAC/GPR地质雷达系统,天线的中心频率为250MHz,收发天线的间距为6m。实测采用剖面法,且收发天线方向与测线方向平行。记录点距为2m,采样频率为3893MHz,单一记录迹线的采样点数为512,迭加次数为16,记录时窗为180ns,若取堤身土体的雷达波速为08~10m/ns,表层浆砌石的雷达波速为10~12m/ns,综合考虑该地层剖面特征,选取雷达波速中值为10m/ns,则此时该雷达系统的最小纵向分辨率为8~10cm。雷达资料的数据处理与地震反射法勘探数据处理基本相同,主要有:①滤波及时频变换处理;②自动时变增益或控制增益处理;③多次重复测量平均处理;④速度分析及雷达合成处理等,旨在优化数据资料,突出目的体、最大限度地减少外界干扰,为进一步解释提供清晰可辨的图像。处理后的雷达剖面图和地震反射的时间剖面图相似,可依据该图进行地质解释。5 成果分析地质雷达资料的地质解释是地质雷达探测的目的。由数据处理后的雷达图像,全面客观地分析各种雷达波组的特征(如波形、频率、强度等),尤其是反射波的波形及强度特征,通过同相轴的追踪,确定波组的地质意义,构制地质——地球物理解释模型,依据剖面解释获得整个测区的最终成果图。地质雷达资料反映的是地下地层的电磁特性(介电常数及电导率)的分布情况,要把地下介质的电磁特性分布转化为地质分布,必须把地质、钻探、地质雷达这三个方面的资料有机结合起来,建立测区的地质——地球物理模型,才能获得正确的地下地质结构模式。雷达资料的地质解释步骤一般为:⑴ 反射层拾取根据勘探孔与雷达图像的对比分析,建立各种地层的反射波组特征,而识别反射波组的标志为同相性、相似性与波形特征等。⑵ 时间剖面的解释在充分掌握区域地质资料,了解测区所处的地质结构背景的基础上,研究重要波组的特征及其相互关系,掌握重要波组的地质结构特征,其中要重点研究特征波的同相轴的变化趋势。特征波是指强振幅、能长距离连续追踪、波形稳定的反射波。同时还应分析时间剖面上的常见特殊波(如绕射波和断面波等),解释同相轴不连续带的原因等。下部架空时的图像,该剖面第三反射同相轴自剖面点4m处断开,形成“背斜”状的强反射层,此现象延续到剖面点8m处,此段浆砌石与下部土体分离导致架空,其范围与已知情况吻合。 通过雷达测试成果的地质解释共圈定出73处浆砌石存在不同程度的隐患或质量较差,这些隐患的类型一般为:①浆砌石厚度较薄;②浆砌石与下部土体分离形成架空;③浆砌石胶结不良或松散;④浆砌石出现裂缝等不良现象。 护砌整体质量较差的堤段多为年久失修严重,浆砌石与下部堤身土体接触差,多形成架(悬)空状态,造成护砌断裂、塌陷等不良现象较普遍,且多具一定规模。而造成上述现象存在的原因,笔者分析后认为浆砌石面存在许多缝隙,且砂浆质量差、少浆,下部又无防渗护层,堤身土体多由粉细砂组成,经降水入渗,粉细砂局部被冲刷淘失,在砌石与堤身土体之间形成空洞,并有继续扩大发展之趋势。该物探成果经开挖验证(见图4——开挖照片),完全符合客观实际,受到了甲方的赞誉。6 结语地质雷达以其高效快速、高精度在护险工程探测中能够发挥重要作用,取得了良好的应用效果,且对浅层或超浅层的工程探测中有着十分广阔的应用前景,然而地质雷达的探测深度和精度与所采用的天线频率有很大关系,天线的频率越低探测深度越大,则精度越低;而天线的频率越高,探测深度越浅,则精度越高。本次采用中心频率250MHz的天线进仅供参考,请自借鉴。希望对您有帮助。
稀疏成份分析及在雷达成像处理中的应用稀疏成份分析是一种新兴的信号分析方法。它以过完备词典为基础,能从有限的观测数据中获得信号的稀疏表示,有效地挖掘信号的自然属性和本质的驱动源,提高变换域的分辨率,为信号处理提供了有力的工具。作为信号处理的重要组成部分,雷达成像技术无论在军事还是民用上都有巨大的应用潜力。雷达成像本质上就是一个信号表示过程,由于高频区雷达目标散射行为具有局部特性,用稀疏成份分析方法能提高雷达图像的质量,有利于图像分析和目标识别。针对雷达成像的应用背景,本文研究了稀疏成份分析中稀疏性度量函数构造的一般准则等理论问题,以及基于稀疏成份分析的雷达成像算法,包括一维距离像、二维逆合成孔径雷达成像和多频段雷达信号综合技术等。研究了稀疏成份分析中度量函数的构造和算法分析等理论问题。利用稀疏成份分析方法研究了高分辨一维距离像稀疏表示的原子构造与相关算法,并对算法的参数估计性能进行了理论分析。研究了基于稀疏成份分析的逆合成孔径雷达成像算法。根据雷达目标散射信号的稀疏表示模型,研究了多频段多分辨雷达信号综合技术。根据雷达目标的理想点散射体模型和几何绕射模型,分析了多频段雷达回波观测信号的联系与差别,并利用稀疏成份分析方法提出了高分辨一维距离像的多频段信号综合成像技术。针对多频段窄带组网雷达检测海上目标的应用背景,根据雷达目标在低分辨回波中的稀疏分布特性和海杂波的分布特性,提出了多雷达距离分辨率匹配处理技术,提高了雷达回波的距离分辨率并实现了多雷达距离分辨率的匹配统一,为多频段窄带雷达信号综合提供了统一的基础。
关于雷达技术的论文英文怎么说
Weather radar has made many improvements in the last 10 There are more improvements on the All of the radars of the past and present work off the same basic principle: the radar equation The basic concept of weather radar works off of the idea of a reflection of The radar sends out a signal, as seen to the right, and the signal is then reflected back to the The stronger that the reflected signal is, the larger the For more basic information on weather radar, click here for a video from the Franklin Institute Science M Image at right is courtesy COMET At the heart of the principle of radar is the radar equation Pr=PtG^2Θ^2H∏^3K^2L/1024(In2)λ^2 * Z/R^2 This equation involves variables that are either known or are directly There is only one value that is missing, but it can be solved for Below is the list of variables, what they are, and how they are Pr: Average power returned to the radar from a The radar sends up to 25 pulses and then measures the average power that is received in those The radar uses multiple pulses since the power returned by a meteorological target varies from pulse to This is an unknown value of the radar, but it is one that is directly Pt: Peak power transmitted by the This is a known value of the It is important to know because the average power returned is directly related to the transmitted G: Antenna gain of the This is a known value of the This is a measure of the antenna's ability to focus outgoing energy into the The power received from a given target is directly related to the square of the antenna : Angular beamwidth of the This is a known value of the Through the Probert-Jones equation it can be learned that the return power is directly related to the square of the angular The problem becomes that the assumption of the equation is that precipitation fills the beam for radars with beams wider than two It is also an invalid assumption for any weather radar at long The lower resolution at great distances is called the aspect ratio H: Pulse Length of the This is a known value of the The power received from a meteorological target is directly related to the pulse K: This is a physical This is a known value of the This constant relies on the dielectric constant of This is an assumption that has to be made, but also can cause some The dielectric constant of water is near one, meaning it has a good The problem occurs when you have meteorological targets that do not share that Some examples of this are snow and dry hail since their constants are around L: This is the loss factor of the This is a value that is calculated to compensate for attenuation by precipitation, atmospheric gases, and receiver detection The attenuation by precipitation is a function of precipitation intensity and For atmospheric gases, it is a function of elevation angle, range, and Since all of this accounts for a 2dB loss, all signals are strengthened by 2 dB : This is the wavelength of the transmitted This is a known value of the The amount of power returned from a precipitation target is inversely since the short wavelengths are subject to significant The longer the wavelength, the less attenuation caused by Z: This is the reflectivity factor of the This is the value that is solved for mathematically by the The number of drops and the size of the drops affect this This value can cause problems because the radar cannot determine the size of the The size is important since the reflectivity factor of a precipitation target is determined by raising each drop diameter in the sample volume to the sixth power and then summing all those values A ¼" drop reflects the same amount of energy as 64 1/8" drops even though there is 729 times more liquid in the 1/8" R: This is the target range of the This value can be calculated by measuring the time it takes the signal to The range is important since the average power return from a target is inversely related to the square of its range from the The radar has to normalize the power returned to compensate for the range Using a relationship between Z and R, an estimate of rainfall can be A base equation that can be used to do this is Z=200*R^ This equation can be modified at the user's request to a better fitting equation for the day or the For more information on the basic physics of Radar, check out the Cassini Radar Web P 回答者:coleyinhe2 - 魔法师 五级 5-26 23:18===========Nobody can be credited with "inventing" The idea had been around for a long time--a spotlight that could cut through But the problem was that it was too advanced for the technology of the It wasn't until the early 20th century that a radar system was first One of the biggest advocators of radar technology was Robert Watson-Watt, a British Great Britain made a big effort to develop radar in the years leading up to World War T Some people credit them with being pioneers in the As it was, the early warning radar system (called "Chain Home") that they built around the British Isles warned them of all aerial This gave the outnumbered Royal Air Force the edge they needed to defeat the German Luftwaffe during the Battle of B While radar development was pushed because of wartime concerns, the idea first came about as an anti-collision After the Titanic ran into an iceburg and sank in 1912, people were interested in ways to make such happenings In 1934 a large-scale Air Defence exercise was held to test the defences of Great Britain and mock raids were carried out on L Even though the routes and targets were known in advance, well over half the bombers reached their targets without Prime Minister Baldwin's statement "The bomber will always get through" seemed To give time for their guns to engage enemy aircraft as they came over, the Army was experimenting with the sound detection of aircraft by using massive concrete acoustic mirrors with microphones at their focal Dr HE Wimperis, the first Director of Scientific Research for the Air Ministry, and his assistant Mr AP Rowe arranged for Air Marshall Dowding to visit the Army site on the Romney Marshes to see a On the morning of the test the experiment was completely wrecked by a milk cart rattling Rowe was so concerned by this failure that he gathered up all the Air Ministry files on the subject of Air D He was so appalled that he wrote formally to Wimperis to say that if we were involved in a major war we would loose it unless something new could be discovered to change the He suggested that the best advisors obtainable should review the whole situation to see whether any new initiatives could be On 12th November Wimperis put this proposal to the Secretary of State and a Committee was set up under Henry TThe idea of using rays to kill or disable people or machines was very popular, so to start things off Wimperis got Professor Hill to estimate the radio energy needed to cause damage to He sent this to Mr Watson-Watt, Superintendent of the Radio Research Station at Slough for his views on the possibility of developing a radio "Death Ray" to melt metal or incapacitate an aircraft Watson-Watt passed the letter to AF Wilkins who reported that there was no possibility of achieving these destructive effects at a distance but that energy reflected from aircraft should be detectable at useful This was reported to the first meeting of the Tizard Committee on 28th January and Rowe was instructed to get quantitative estimates for Wilkins made further calculations from which Watson-Watt wrote a memorandum proposing a system of radio-location using a pulse/echo The Committee gave this a very favourable reception and Wimperis asked Dowding for £10,000 to investigate this new method of Dowding, though very interested, said he must have a simple practical demonstration to show feasibility before committing scarce funds to the For this demonstration Watson-Watt and Wilkins decided to make use of transmissions from the powerful BBC short-wave station at Daventry and measure the power reflected from a Heyford bomber flying up and down at various Detection was achieved at up to 8 miles and the £10,000 was A site at Orfordness was chosen to do the detection experiments over the Aerials mounted on three pairs of 75ft wooden lattice masts were installed and detection ranges of 17 miles were These were rapidly increased to 40 miles by J Work was done to show how map position and height might be determined and Watson-Watt submitted proposals for a chain of stations to be erected round the coast to provide warning of attack and to tell fighters where to engage the He suggested that a full-scale station should be built at once, to be followed, if successful, by a group of stations to cover the Thames Estuary and then by a final chain covering the South and East Construction of 5 stations was authorised and the one at Bawdsey was in operation by August The others followed shortly Plots were to be telephoned to a central operations room and combined with data from the Royal Observer Corps and the radio direction-finding In February 1936 Bawdsey Manor became the centre for the expanding research team and Tizard inspired the RAF at Biggin Hill to investigate fighter control and interception Their results convinced him that effective interceptions could be obtained against mass raids by day, but not against dispersed attackers at He therefore pressed for equipment to go into fighters for them to find and engage targets when positioned within a few Initial tests using a large television transmitter on the ground operating on a wavelength of 6 metres and a receiver in a Heyford Bomber with an aerial between its wheels gave detection ranges of over 10 To get a transmitter into an aircraft and reduce the size of the aerial a much lower wavelength was Bowen installed a crude equipment operating at 1 metre in an Anson and in the autumn of 1937 aircraft were detected and also Naval ships several miles away in appalling From then on Air Interception (AI) and Air to Surface Vessel (ASV) equipments were Further Air Defence Trials showed that better detection of low flying aircraft was needed and Chain Low (CHL) stations were evolved from Coastal Defence (CD) equipments which had been developed for the A Gun laying equipments (GL) were developed and also equipments to improve navigation (GEE) and bombing (OBOE) and (H2S) These are dealt with in the following
液态氧气 护顶板 感应光束
About RadarThe concept of radar formed in the early 20th century, before and after the Second World War was the rapid The principle of radar, the device is a transmitter antenna through the electromagnetic energy of a shooting at the direction of the space, in the direction of objects encountered reflection of electromagnetic waves; radar antenna to receive the reflected waves, to the receiving equipment to carry out processing, extraction The object was related to some of the information (the target objects to the distance between radar, or the rate of change from the radial velocity, location, height, ) CW radar and radar is divided into two major categories of radar Radar pulse as a result of easy to achieve precise location and receive echo in the resting pulse during the launch, the receiving antennas and antenna can be used to launch the same deputy antennas, and therefore in the development of radar in the main UN Measuring the distance is a measure of the actual launch with the pulse-echo pulse of the time difference between, as a result of electromagnetic waves in order to spread the speed of light, which can be converted into the precise distance from the The goal is to position the antenna to use sharp beam position Elevation on the narrow beam angle of elevation According to the elevation and distance will be able to calculate the target When the radar and the relative motion between the target, the radar echoes received by the target frequency radar and launch a different frequency, known as the difference between the Doppler From the Doppler frequency can be extracted from the main message is one of the radar and the distance between the target rate of When the goal of interference with the clutter at the same time present in the same spatial resolution of the radar unit, among them the use of Doppler radar frequency interference from the different clutter in the detection and tracking the Radar has the advantage of both day and night to detect long-range goals, and not subject to fog, cloud and rain to stop, with all-weather, all the characteristics and a certain degree of As a result, it has become not only essential military electronic equipment, and is widely used in socio-economic development (such as weather forecasting, resource exploration, environmental monitoring, ) and scientific research (study of celestial bodies, atmospheric physics, ionospheric structure, ) And on-board airborne synthetic aperture radar remote sensing has become a very important The spatial resolution of up to a few tens of meters, and has nothing to do with Radar in the flood monitoring, sea ice monitoring, soil moisture survey of forest resources inventory, such as the Geological Survey shows a very good application 用翻译机翻得。你改一下明显的错误,很快可以搞定
关于雷达技术的论文怎么写的
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同学,我是田雨,请你独立完成作业,如果有不懂的可以直接来问我
田雨的作业都跑到这里来了……
关于雷达技术的论文英文翻译怎么写
About RadarThe concept of radar formed in the early 20th century, before and after the Second World War was the rapid The principle of radar, the device is a transmitter antenna through the electromagnetic energy of a shooting at the direction of the space, in the direction of objects encountered reflection of electromagnetic waves; radar antenna to receive the reflected waves, to the receiving equipment to carry out processing, extraction The object was related to some of the information (the target objects to the distance between radar, or the rate of change from the radial velocity, location, height, ) CW radar and radar is divided into two major categories of radar Radar pulse as a result of easy to achieve precise location and receive echo in the resting pulse during the launch, the receiving antennas and antenna can be used to launch the same deputy antennas, and therefore in the development of radar in the main UN Measuring the distance is a measure of the actual launch with the pulse-echo pulse of the time difference between, as a result of electromagnetic waves in order to spread the speed of light, which can be converted into the precise distance from the The goal is to position the antenna to use sharp beam position Elevation on the narrow beam angle of elevation According to the elevation and distance will be able to calculate the target When the radar and the relative motion between the target, the radar echoes received by the target frequency radar and launch a different frequency, known as the difference between the Doppler From the Doppler frequency can be extracted from the main message is one of the radar and the distance between the target rate of When the goal of interference with the clutter at the same time present in the same spatial resolution of the radar unit, among them the use of Doppler radar frequency interference from the different clutter in the detection and tracking the Radar has the advantage of both day and night to detect long-range goals, and not subject to fog, cloud and rain to stop, with all-weather, all the characteristics and a certain degree of As a result, it has become not only essential military electronic equipment, and is widely used in socio-economic development (such as weather forecasting, resource exploration, environmental monitoring, ) and scientific research (study of celestial bodies, atmospheric physics, ionospheric structure, ) And on-board airborne synthetic aperture radar remote sensing has become a very important The spatial resolution of up to a few tens of meters, and has nothing to do with Radar in the flood monitoring, sea ice monitoring, soil moisture survey of forest resources inventory, such as the Geological Survey shows a very good application 用翻译机翻得。你改一下明显的错误,很快可以搞定
最小斑点重量 - 确定细胞的最小数目(其中一个细胞是单一功率读数在任一范围或方位角),必须是在一个情节之前它被认为是用于提取
This paper discusses the basic principles of ultrasonic distance measurement, measurement, calculation method, and based on the detailed application of ultrasonic distance measurement reversing radar system The system will be the microprocessor technology and ultrasonic distance measurement technology, sensor technology, combining vehicle can be detected in the reverse process, the obstacles with the motor car the distance, through the LCD display barrier distance, direction, and in accordance with obstacles and rear distance issued immediately different grades the warning