广域电磁法接收机数字信号FFT实时实现技术

针对广域电磁法（WFEM）接收机各频组数字信号快速傅里叶变换（FFT）点数不统一、低频组点数大不适合现场可编程门阵列（FPGA）实时实现的技术难题,本文采用插值和抽取相结合的抽样率转换方法,提出了满足广域电磁法接收机要求的等长度FFT变换技术,将各频组FFT变换点数统一变换到1024点,并以广域电磁法接收机实际采集到的电场信号进行了测试,最终在EP2C35F484C8 FPGA芯片上实现了1024点FFT变换,最高响应频率达到了93.84 MHz,完成1024点广域电磁信号FFT运算最快只需34 μs,并且能够有效提取广域电磁信号的振幅和相位信息.结果表明：在对广域电磁法接收机信号进行FIR低通滤波后,能够通过插值和抽取相结合的方法,将各个频组FFT变换的长度统一变换成1024点,实现广域电磁信号的FFT实时变换.本文提出的等长度FFT变换技术能够满足新一代高性能广域电磁法接收机FFT实时变换的需求.     

提升气象卫星高速数据解调性能的研究与试验

随着风云气象卫星事业的飞速发展,卫星观测通道数量不断增加、时间和空间分辨率不断提高,原始数据码速率已经由每秒几十兆比特上升为几百兆比特,不久将达到千兆以上.卫星的主要任务是获取遥感数据,从某种角度而言,卫星的价值等价于遥感数据的质量和大小.原始数据通过无线电载波传输至地面站,从载波中准确无误地解调出原始数据,是风云卫星...     

高性能FPGA处理器在叠前可希霍夫偏移中的应用

笔者提出了SONIC可重新设置协处理器，它用来通过现场可编程(FPGA)技术加速三维叠前可希霍夫时间偏移(PSTM)。PSTM程序中费时最多的核心部分被编人基于FPGA的协处理器平台中。它作为一个硬件加速器附加在工作站上，通过并行合到一个FPGA芯片上来改善其运算性能。计算机模拟结果显示出SONIC平台在50MHz运行时，每秒钟可以计算5千万点的可希霍夫加法运算。这比参考的2．4GHz奔腾4工作站快15．6倍，该平台具有可重置性能，加上令人满意的运算速度，显示了它在地震数据处理业的广泛应用前途。     

苏州东方之门基坑工程的变形监测与分析

苏州东方之门基坑工程是一个开口型的超大深基坑工程,长约205m,宽约130m,基坑开挖深度除局部落深区外为20.5m.对基坑工程施工过程中获得的基坑周围地面变形、地下管线的变形和立柱沉降的监测数据进行整理和分析,得到了一些有益的结论,可为苏州地区软土场地深基坑工程的设计、施工和监测提供参考.     

三分量磁通门磁变仪探头正交误差对定向的影响

本文分析了磁通门磁变仪探头三分量正交度误差对定向的影响并提出了减小其影响的措施。     

WWW服务器CGI程序设计语言分析

通用网关接口是Ｗｅｂ管理员最有用的工具之一,它是ｗｗｗ服务器上维护主页Ｈｏｍｅｐａｇｅ,提供基于ＷＢ的交互式操作,定单输入系统,Ｗｅｂ电子商务、ＳＱＬ数据库接口、多媒体Ｗｅｂ动画的源泉,本文分析ＷＷＷ服务器进行ＣＧＩ程序设计的各种编程语言的优势和局限性,指出Ｊａｖａ编程语言将是网上ＣＧＩ程序设计的最佳编程工具。     

一种固定选图数的实时幸运成像算法

幸运成像技术是一种从大量短曝光图像中选取少量幸运好图进行配准、叠加的高分辨率图像恢复技术,能够有效减小大气湍流对图像质量的影响,但传统的基于中央处理器(Central Processing Unit,CPU)的幸运成像算法难以实现实时化.利用现场可编程门阵列(Field Programmable Gate Array,...     

数字化地磁仪器的调试维护与应用

本文总结了大连地震台安装，调试，维护与应用CTM－DI磁力仪和GMB磁通门磁力仪的基本做法与经验。     

The Middle Triassic (Anisian) Otter Sandstone biota (Devon,UK): review,recent discoveries and ways ahead

The Middle Triassic (Anisian) Otter Sandstone was laid down mostly by braided rivers in a desert environment and is now well exposed along the south-east Devon coast in south-west England, part of the ‘Jurassic Coast’ World Heritage Site. It yields uncommon and generally fragmentary fossils, principally of vertebrates, including fish, temnospondyl amphibians and reptiles such as rhynchosaurs, predatory archosaurs, and small superficially lizard-like forms. These provide important information about a freshwater and terrestrial ecosystem that marks recovery from the end-Permian mass extinction, but pre-dated the appearance of dinosaurs and mammals. The constantly eroding Otter Sandstone exposures continue to reveal new taxa (for example, freshwater sharks). Furthermore, microvertebrate material obtained by sieving bone-bearing levels has the potential to further expand the faunal list. Newly discovered associated and articulated vertebrate remains, including small tetrapods, improve knowledge of whole-body anatomy and facilitate systematic work. Invertebrate burrows and reptile footprints provide information on ecological interactions and detailed bed-by-bed collecting casts light on taphonomic processes and faunal changes over time.     

Eolian transport of salts—A case study in the area of Lake Ebinur (Xinjiang, Northwest China)

In the Ebinur region of Western Dzungaria, strong wind flows from Dzungarian Gate predetermine the widespread development of deflation processes. As a result of human-induced desiccation of Lake Ebinur, a new source of the loose material—the dry lakebed—has formed, which has intensified dust storms in this region. Annual dynamics of the frequency and intensity of dust storms and the amount and chemical composition of salts in the eolian material deposited in the area have been studied. The frequency of dust storms and the intensity of dust and salt deposition regularly decrease with an increase in the distance from the dry lake bottom (playa). The amount of dust deposition ranges from 600 (near the lake) to 70 (100–200 km from the lake) g/m²/a. The amount of salts precipitating with dust is mainly from 14 to 27 g/m²/a; the maximum registered amount of salt deposition is 77 g/m²/a. As shown in our study, the farther from the lake, the higher the portion of sulfate and calcium and the smaller the portion of chloride and sodium ions in the composition of salts.