共查询到20条相似文献,搜索用时 15 毫秒
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一些学者对双绞线电磁干扰进行研究,建立了精确的干扰模型,但并不适合工程应用.为此根据电磁兼容优势效应理论,推导出双绞线传导干扰主要由差模电流引起,辐射干扰主要由共模电流引起.分别利用广义二端口网络模型和电流元分析方法建立双绞线串扰和辐射的简化模型,从而有效估算双绞线串扰电压和对外辐射场的大小,最后给出滤波连接器的选择方法,为工程人员采取有效措施抑制互连设备电磁干扰提供了理论帮助. 相似文献
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D. S. Polydorou P. G. Babalis C. N. Capsalis 《Journal of Infrared, Millimeter and Terahertz Waves》1999,20(3):461-472
Propagation Line Of Sight (LOS) indoor environment is studied through a new statistical model for the fast fading statistics which is based on the assumption of a small number of scatterrers. The analytical expression for the probability density function of fast fading statistics is presented and is applied in a mixture probability density function for the received signal envelope in order to incorporate shadowing. The new models are validated by measurements which have been conducted at NTUA in three different frequency bands, 1.8 GHz, 30 GHz and 60 GHz, in corridors. Finally the new models are compared with the traditional Rice and Rice-Lognormal respectively. 相似文献
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为预测无线传感器网络通信质量并指导节点部署与拓扑控制,研究提出小麦农田信道多尺度建模方法.根据农田作物生长态势及其与信号传播路径的相对关系,提取环境关联参数.按作物遮挡程度不同,分别提出和采用对数模型与概率分布模型进行描述分析,结合实测样本数据对模型因子进行拟合,建立了小麦农田多径衰落信道下的经验模型并进行模型评价.结果表明,无遮挡条件下采用环境关联参数拟合的大尺度模型结果的相关系数在0.98以上;遮挡条件下,采用多尺度概率分布模型描述的平均偏差在0.04以下,达到了对小麦农田多径信道准确描述的预期研究目标. 相似文献
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基于OpenGL与3DS Max的三维场景建模 总被引:7,自引:0,他引:7
介绍了如何利用OpenGL技术与3DS Max软件快速地构建三维场景,并对3DS模型在OpenGL程序中的应用作了介绍。通过降低OpenGL建立复杂三维模型的难度,减少建模的工作量。通过利用专业建模软件3DS Max的优点,较快地建立复杂的模型,并利用OpenGL的编程接口对建立的模型进行实时绘制和交互控制,降低建模时间,加快系统开发进程。 相似文献
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This paper reports the results of measurements of 900 MHz narrow-band radio wave propagation in four tunnels with pedestrians and vehicles. Analysis of the measured data files shows that the power distance factor ranges from 1.87 to 4.44. The power attenation rate with distance is insensitive to the location of the transmit antenna in the cross section of a tunnel, but the transmit antenna insertion loss is. The log-normal distribution fits slow variation of the received signals. The Racian distribution closely describes fast fading in the straight sections of tunnels. However, the Rayleigh distribution does not fit the fast fading in the curved sections of tunnels, as expected. 相似文献
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SAR图像统计建模研究综述 总被引:2,自引:0,他引:2
SAR图像统计建模旨在通过统计的方法描述SAR图像数据,以揭示SAR图像的统计特性,进而为地物散射机理的深入理解、有效SAR图像解译算法的构建、大样本SAR图像的仿真等提供技术支持.SAR图像统计建模是SAR图像解译的基础研究之一,具有较大的应用价值.本文首先从SAR图像统计建模技术的历史沿革、研究现状开始,以由乘积模型发展的SAR图像统计模型为主线,对SAR图像统计建模相关技术进行了较为全面的综述. 相似文献
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Har Dongsoo Bertoni Henry L. Kim Seongcheol 《International Journal of Wireless Information Networks》1997,4(2):113-123
Linear microcells employing low base stationantennas have been proposed for emerging PCS systems. Insuch systems, the characteristics of the propagation online-of-sight (LOS) radio links will fundamentally determine the system performance. In thiscontext, it is meaningful to discuss the effect onsystem design of the two commonly used propagationmodels, the two-slope model and the single-slope model.In this paper we present several methods tocompare the frequency reuse pattern and base stationseparation based on these two propagation models, andverify the importance of correct propagation modeling for efficient system design. We considerinterfering signals coming from two cochannel basestations in the first tier, and include slow fading losswhen comparing system performances. Based on systemdesign results and subsequent performance, thetwo-slope model is recommended for LOS PCSmicrocells. 相似文献
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为建立更为准确的全覆盖、全应用、全频谱的5G无线信道模型,提出通过认知无线电与深度神经网络相结合的方法研究无线电波传播特性。根据传统无线传播模型并考虑到不同传播环境,根据信道大尺度衰落特性(包括路径损耗、阴影衰落和小尺度衰落特性)的统计结果,通过BP算法提取特征,并应用FeatureTools进行深度特征综合建立特征方程,计算特征变量与传播损耗的相关系数,进行相关系数的置信区间及变量独立性检验,最终筛选出22个特征并排序。基于深度残差网络建立传播路径损耗的回归模型,结合批正则化过拟合测算平均接收功率,为建立更精确的无线信道模型提供了量化依据,并最终在测试数据集上取得均方根误差8.36(本地)和10.03(云端)的成绩,对工程实践具有较强的参考价值。 相似文献
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在针对一种全转动副三平移并联解耦机器人进行了研究,在运动学正解和逆解分析的基础上讨论了其运动学特性,并应用SimMechanics仿真平台对并联机器人的控制策略进行了研究。该机构由三个相同形式的支链构成,连杆与连杆之间,连杆与基座之间均为转动副连接,动平台只做三个方向的平移运动。通过对建立的Matlab/SimMechanics并联机器人模型进行仿真,验证了机构运动学分析的正确性。最后设计了PID控制器,实现了对动平台轨迹的控制。研究结果表明,此建模方法和控制方案是可行的,为并联机构的建模、控制提供了借鉴和参考。 相似文献
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扩展频谱通信技术是一种信息传输方式。其系统占用的频带宽度远远大于要传输的原始信号带宽(或信息比特率)。本论文工作的重点是在Max plus2开发平台上具体实现这个扩频系统,并对系统中的每个模块进行相应的功能仿真。 相似文献
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The random variability of fetal heart rate (FHR) is of practical importance in obstetric management. The variability is not white, however, and cannot be adequately described by its variance alone. We have modeled FHR variability as the scalar output of a multivariate, nonlinear stochastic process. An adaptation of the Kalman filter algorithm is used as part of an approximate maximum likelihood estimator of the process parameters. The filter algorithm permits recording artifacts to be disregarded, by treating them as "missing" observations. 相似文献