Efficient Strip-Mode SAR Raw-Data Simulator of Extended Scenes Included Moving Targets Based on Reversion of Series

The Synthetic Aperture Radar(SAR)raw data generator is required to the evaluation of focusing algorithms,moving target analysis,and hardware design.The time-domain SAR simulator can generate the accurate raw data but it needs much time.The frequency-domain simulator not only increases the efficiency but also considers the trajectory deviations of the radar.In addition,the raw signal of the extended scene included static and moving targets can be generated by some frequency-domain simulators.However,the existing simulators concentrate on the raw signal simulation of the static extended scene and moving targets at uniform speed mostly.As for the issue,the two-dimensional signal spectrum of moving targets with constant acceleration can be derived accurately based on the geometric model of a side-looking SAR and reversion of series.And a frequency-domain algorithm for SAR echo signal simulation is presented based on the two-dimensional signal spectrum.The raw data generated with proposed method is verified by several simulation experiments.In addition to reveal the efficiency of the presented frequency-domain SAR scene simulator,the computational complexity of the proposed method is compared with the time-domain approach using the complex multiplication.Numerical results demonstrate that the present method can reduce the computational time significantly without accuracy loss while simulating SAR raw data.

Novel modelling strategies for high‑frequency stock trading data

Full electronic automation in stock exchanges has recently become popular,generat-ing high-frequency intraday data and motivating the development of near real-time price forecasting methods.Machine learning algorithms are widely applied to mid-price stock predictions.Processing raw data as inputs for prediction models(e.g.,data thinning and feature engineering)can primarily affect the performance of the prediction methods.However,researchers rarely discuss this topic.This motivated us to propose three novel modelling strategies for processing raw data.We illustrate how our novel modelling strategies improve forecasting performance by analyzing high-frequency data of the Dow Jones 30 component stocks.In these experiments,our strategies often lead to statistically significant improvement in predictions.The three strategies improve the F1 scores of the SVM models by 0.056,0.087,and 0.016,respectively.

Piecewise linear mapping algorithm for SAR raw data compression

When the saturation degree (SD) of space-borne SAR raw data is high, the per-formance of conventional block adaptive quantization (BAQ) deteriorates obviously. In order to overcome the drawback, this paper studies the mapping between the average signal magnitude (ASM) and the standard deviation of the input signal (SDIS) to the A/D from the original reference. Then, it points out the mistake of the mapping and introduces the concept of the standard deviation of the output signal (SDOS) from the A/D. After that, this paper educes the mapping between the ASM and SDOS from the A/D. Monte-Carlo experiment shows that none of the above two mappings is the optimal in the whole set of SD. Thus, this paper proposes the concept of piecewise linear mapping and the searching algorithm in the whole set of SD. According to the linear part, this paper gives the certification and analytical value of k and for nonlinear part, and utilizes the searching algorithm mentioned above to search the corresponding value of k. Experimental results based on simulated data and real data show that the performance of new algorithm is better than conventional BAQ when raw data is in heavy SD.

Motion estimation in wide band synthetic aperture sonar based on the raw echo data using the method of displaced phase center antenna

Phase errors in synthetic aperture sonar (SAS) imaging must be reduced to less than one eighth of a wavelength so as to avoid image destruction. Most of the phase errors occur as a result of platform motion errors, for example, sway yaw and surge that are the most important error sources. The phase error of a wide band synthetic aperture sonar is modeled and solutions to sway yaw and surge motion estimation based on the raw sonar echo data with a Displaced Phase Center Antenna (DPCA) method are proposed and their implementations are detailed in this paper. It is shown that the sway estimates can be obtained from the correlation lag and phase difference between the returns at coincident phase centers. An estimate of yaw is also possible if such a technique is applied to more than one overlapping phase center positions. Surge estimates can be obtained by identifying pairs of phase centers with a maximum correlation coefficient. The method works only if the platform velocity is low enough such that a number of phase centers from adjacent pings overlap.

EFFICIENT STRIP-MODE SAR RAW SIGNAL SIMULATION OF MIXED TARGETS BASED ON ACCURATE 2-D SPECTRUM

An accurate and efficient Synthetic Aperture Radar(SAR)raw data generator is of considerable value for testing system parameters and verifying imaging algorithms.Nevertheless,the existing simulator cannot exactly handle the case of the fast moving targets in high squint geometry.As for the issue,the analytical expression for the two Dimensional(2-D)signal spectrum of moving targets is derived and a fast raw echo simulation method is proposed in this study.The proposed simulator can accommodate the moving targets in the high squint geometry,whose processing steps of the simulation are given in detail and its computational complexity is analyzed.The simulation data for static and moving targets are processed and analyzed,and the results are given to validate the effectiveness of the proposed approach.

平板扫描仪RAW和默认参数捕获数据差异

本文测量了三种平板扫描仪RAW和默认参数扫描数据捕获的差异,估计两种扫描方式对中性灰再现的影响。实验结果表明,默认参数扫描和参数关闭扫描对中性灰影响不大,因为默认调整参数主要作用于高光和暗调区域。

RAWS异常强降水数据现场核验方法及应用

区域自动气象站记录到历史罕见、超历史或显著超过邻近站的异常强降水时,常规数据质量控制(QC)方法一般判为疑误数据。本文对这种情况提出了现场核验的方法,包括核验的启动,传感器误差核查,仪器性能和探测环境评估,其他资料辅助判别,以及作出核验结论、形成核验报告等步骤。并利用一次实例对这种方法的有效性和适用性进行了检验。

冲量法固体推进剂燃速测试原始数据有效性判定

为了定义并明确冲量法燃速测试的应用边界,通过对“推进剂药柱点火不同步”、“存在侵蚀”、“推进剂药柱同心度不好”3种情况下终了燃面偏离设计值的分析,提出以最大压强尤其是最大推力处的下降速率作为冲量法燃速测试数据有效性的判据,该判据同时解决了“裸露的推进剂药柱表面同步点火”无法评判的问题。根据燃烧室在无加质条件下燃气质量的变化规律,计算获得燃烧室压强随时间的改变趋势,与试验压强-时间曲线进行对比,提出数据有效性因子K,给出了原始数据有效性的数值判定方法。研究表明,当数据有效性因子K=1~1.2时,冲量法燃速测试结果与恒压发动机燃速测试结果一致性较好,数据有效。同时验证了喷管烧蚀会影响冲量燃速测试的压强范围,但不影响燃速测试结果。

遥感卫星图像原始数据误码率检测方法

在分析遥感卫星原始数据质量检测的基础上,文章提出了一种基于空帧数据统计在轨遥感卫星图像原始数据误码率的检测方法,该方法利用空帧数据在原始数据中有较多的占比的特征,利用空帧数据的误码率代表原始数据的误码率。经多颗卫星工程应用验证,结果表明:该方法简单实用,既统计出误码率,又记录了误码出现的具体位置和错误情况,可支撑接收站设计最优数据接收方案,为提高遥感卫星图像质量提供基础。

数码单反相机焦平面光电转换函数的测量及分析

为了在光学实验中合理应用数字成像设备,需要获取并处理其物理输入量与数字输出量之间的关系。基于ISO 14524:2009标准,对数码单反相机Canon EOS 500D的焦平面光电转换函数进行了实验测量及数据分析。通过比较不同尺寸像素区域及不同图片格式对测量结果的影响,发现焦平面光电转换函数的测量偏差随像素区域尺寸的减小而增大,而RAW和JPEG两种文件格式的数字输出值与焦平面曝光量的关系分别为线性和非线性。当单反相机用作光分布记录测量的仪器时,采用直接反应传感器接收的辐照度信息的RAW格式作为输出数据,可以获得较大的动态范围,理论上可以避免相机非线性变换等后续处理带来的影响,经过必要的校正可以更精确地表示场景信息。

基于逆变器多模态输出电压的IGBT微小故障特征提取

针对逆变器IGBT模块发生微小故障引起特征信号变化,相较于电路正常运行信号十分微弱、难以检测的问题,提出一种通过采样逆变器端口输出电压来提取IGBT微小故障特征参数的方法。方波控制策略下,逆变器输出电压包含稳态和暂态两种工作模态,可进一步划分为6个暂态模态和6个稳态模态,因此利用Elman神经网络完成工作模态划分。暂态工作模态中,通过将开关状态下的逆变器等效成二阶系统,完成系统的参数辨识;基于此提出一种输出电压原始数据和系统辨识参数相融合的方法,提取二阶系统的超调量、峰值时间以及暂态电压斜率作为暂态故障特征参数,既降低了实际系统原始数据噪声的干扰,又避免了等效二阶系统参数辨识误差对故障特征提取效果的影响。仿真和实验验证了所提方法的有效性。

Rapid prediction of floating and sinking components of raw coal

A model that rapidly predicts the density components of raw coal is described.It is based on a threegrade fast float/sink test.The recent comprehensive monthly floating and sinking data are used for comparison.The predicted data are used to draw washability curves and to provide a rapid evaluation of the effect from heavy medium induced separation.Thirty-one production shifts worth of fast float/sink data and the corresponding quick ash data are used to verify the model.The results show a small error with an arithmetic average of 0.53 and an absolute average error of 1.50.This indicates that this model has high precision.The theoretical yield from the washability curves is 76.47% for the monthly comprehensive data and 81.31% using the model data.This is for a desired cleaned coal ash of 9%.The relative error between these two is 6.33%,which is small and indicates that the predicted data can be used to rapidly evaluate the separation effect of gravity separation equipment.

公路工程施工定额测定及原始数据处理方法

随着我国经济的快速发展,给我国基础设施建设,特别是公路交通设施建设提供了稳定的保障。施工定额作为公路工程定额体系的重要基础,在企业的市场竞争中起到关键作用。而在公路施工定额原始数据测定过程中存在一定影响因素,导致观测的原始数据存在一定的差异。因此,为做好公路施工定额原始数据处理工作,本文通过相关理论基础知识阐述,并结合具体工程案例进行分析,从而得出应用格拉布斯准则处理公路定额原始数据,使原始数据更收敛,界定更科学,保证公路工程施工定额数据更加可靠,从而提高机械设备和生产能力的利用率。

头颅CT原始数据重建技术在眼眶细小骨折诊断中的应用

目的探讨头颅CT原始数据重建技术在眼眶细小骨折诊断中的应用效果。方法收集2021年8月至2022年1月苏北人民医院经头颅CT提示“可疑眼眶骨折”的45例(56处)患者的临床和影像资料,利用头颅CT原始数据作重建分析,通过多参数优化对眼眶区进行图像重建,总结分析重建后的图像在眼眶细小骨折诊断中的价值。结果所有患者利用头颅CT原始数据重建技术均成功对眼眶区进行优化重建。眼眶区的主要结构及细小结构均能在重建图像上完整、清晰显示,其中检出眼眶骨折直接征象32例,眼眶骨折间接征象37例,未见骨折8例,可疑骨折5例。结论头颅CT原始数据重建技术能提高兴趣区重建图像的空间分辨率及清晰度,应用于眼眶细小骨折的诊断时能为临床提供更为优质全面的影像资料,显著提高骨折检出率。

基于数据挖掘探讨辅助润肠通便保健食品组方规律及用药特点

目的:通过数据挖掘分析辅助润肠通便保健食品的组方规律及用药特点,为辅助润肠通便保健食品的组方及新产品开发提供参考。方法:通过检索国家市场监督管理总局(SMAR)上发布的辅助润肠通便保健食品信息,筛选含有中药原料的有效组方数据,使用中医传承辅助平台V2.5进行数据的统计和分析,总结出配方的规律和特点,并挖掘新组方。结果:检索辅助润肠通便保健食品共273个,其中,208个保健食品中含中药原料,占比76.2%;仅有辅助润肠通便功能的154种,2种及以上保健功能的119种;使用频次≥15的中药原料有12味,累计使用352次(占总数的45.7%),分别为:芦荟(76)、决明子(62)、火麻仁(45)、莱菔子(24)、郁李仁(22)、山楂(19)、茯苓(18)、蜂蜜(18)、当归(17)、黄芪(17)、何首乌(17)、番泻叶(17);通过关联规则中的组方规律分析,得出9个新组方。结论:该研究能够为含中药原料的辅助润肠通便保健食品开发,以及方剂配伍研究提供数据基础和新思路,也可为该类保健食品的辨证分型开发及选用提供依据。

智能控制器在水泥生料在线配料中的应用

从水泥生料配料行业背景,引出工业级智能控制器在水泥生料自动配料中的应用。介绍了智能控制器产生的原因、特点及软硬件组成;通过水泥生料的配比案例,分析了智能控制器实时采集、处理、计算、调整水泥生产数据的过程,以实现水泥生料的自动配制与控制。应用结果显示,智能控制器协同在线分析仪的应用,缩短了取样周期,实现了精准、快速的实时管理,保证了产品质量的稳定;同时能自动完成多个标号水泥生料的配料和生产数据的采集并及时上传至管理者,以便技术人员对工艺流程作进一步优化和调整。智能控制器比上位机更加稳定可靠,在先控行业具有良好的应用前景。

基于DBN的故障特征提取及诊断方法研究

随着装备日趋复杂化,依靠专家经验或信号处理技术人工提取和选择故障特征变得越来越困难。此外,以BP神经网络、SVM为代表的浅层模型难以表征被测信号与装备健康状况之间复杂的映射关系,且面临维数灾难等问题。结合深度置信网络(DBN)在提取特征和处理高维、非线性数据等方面的优势,提出一种基于深度置信网络的故障特征提取及诊断方法。该方法通过深度学习利用原始时域信号训练深度置信网络并完成智能诊断,其优势在于能够摆脱对大量信号处理技术与诊断经验的依赖,完成故障特征的自适应提取与健康状况的智能诊断,该方法对时域信号没有周期性要求,具有较强的通用性和适应性。在仿真数据集和轴承数据集上进行了故障特征提取和诊断实验,实验结果表明:本文提出的方法能够有效地从原始信号中进行多种工况、多种故障位置和多种故障程度的故障特征提取和诊断,并且具有较高的故障识别精度。

SAFIRE与FBP重建法对CT图像噪声及扫描剂量影响的比较研究

目的评价应用原始数据迭代重建法(SAFIRE)与滤波反投影法(FBP)对CT图像噪声及扫描剂量的影响。方法应用128层双源Flash CT,在120kV、100kV、80kV、70kV条件下,分别采用200mAs、170mAs、140mAs、110mAs、80mAs、50mAs、20mAs扫描剂量扫描水模,采用原始数据迭代重建法与滤波反投影法分别重建,不同管电压条件下,以预设扫描管电流200mAs FBP重建图像作为对照,比较不同扫描剂量、不同重建方法图像噪声并分析扫描剂量降低的潜力。结果原始数据迭代重建法随着迭代次数的增多,120kV管电压时降低45%～75%的扫描剂量,100kV管电压时降低45%～75%的扫描剂量,80kV管电压时降低45%～60%的扫描剂量,70kV管电压时降低15%～60%的扫描剂量,可以得到与200mAs FBP重建法噪声无统计学差异的图像。结论 SAFIRE重建法与FBP重建法比较可以显著降低图像噪声,从而降低扫描剂量并同时得到满意图像。

区域海洋地质数据库建设纲要

区域海洋地质数据库是中国地质调查局基础数据库的一个重要组成部分,是实现地质调查基础性与公益性战略部署的依托。根据区域海洋地质数据库建设的目标与任务,在数据结构和实施步骤等方面进行了初步研究。区域海洋地质数据库及其管理信息系统适合采取基于Web系统的三层体系结构,在数据构成上亦分为区域海洋地质调查原始资料与成果资料,其中元数据库的建设对数据库的应用非常重要,用户可以通过元数据了解数据的存在性、适宜性、有效性等,确定数据的使用方法,因此,元数据库的建设应采用国际已经普遍认可的ISO/TC211发布的ISO19115空间元数据标准。

中药数据优化处理探讨

要获得高信息含量的、有用的知识,理想情况就是原始数据是不含噪声的正确数据。中药数据库系统是数据库技术在中药领域的运用,是在中药信息研究过程中,对大量不规范的原始数据进行分析、整理、补充、完善建立起来的。本研究结合在建的中草药信息系统回顾中药数据处理加工中的若干关键问题。