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矩形隧道中的多波模传播特性 被引量:17
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作者 霍羽 徐钊 郑红党 《电波科学学报》 EI CSCD 北大核心 2010年第6期1225-1230,共6页
分别推导出矩形隧道内多模式电磁波综合作用下的隧道壁反射衰减公式,以及由隧道壁粗糙度、倾斜度引起的散射衰减公式,建立了多波模传输理论。据此分析的电磁波传播特性显示:频率越高,高次模的影响越大,隧道壁粗糙度和倾斜度的影响亦随... 分别推导出矩形隧道内多模式电磁波综合作用下的隧道壁反射衰减公式,以及由隧道壁粗糙度、倾斜度引起的散射衰减公式,建立了多波模传输理论。据此分析的电磁波传播特性显示:频率越高,高次模的影响越大,隧道壁粗糙度和倾斜度的影响亦随之增大;且水平极化波和垂直极化波的衰减值之差逐渐减小,收敛在稳定值。所得结论与传统只分析基模衰减公式的电磁波传输理论相比,更接近于实际测量数据和几何光学的仿真结果。 展开更多
关键词 电波传播 多波模 衰减 传播特性 矩形隧道
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煤矿巷道壁粗糙度对电磁波传播的影响 被引量:5
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作者 霍羽 房咪咪 +1 位作者 刘逢雪 徐钊 《工矿自动化》 北大核心 2013年第3期43-45,共3页
根据多波模传输理论推导出多波模综合作用下因巷道壁粗糙度引起的电磁波衰减计算公式,并采用多波模模型仿真分析巷道壁粗糙度对电磁波衰减特性的影响。Matlab仿真结果表明,巷道壁粗糙度对电磁波衰减特性的影响随频率升高而增大,由于波... 根据多波模传输理论推导出多波模综合作用下因巷道壁粗糙度引起的电磁波衰减计算公式,并采用多波模模型仿真分析巷道壁粗糙度对电磁波衰减特性的影响。Matlab仿真结果表明,巷道壁粗糙度对电磁波衰减特性的影响随频率升高而增大,由于波导效应和巷道壁粗糙度的共同作用,煤矿井巷电波传播存在一个0.4~2GHz的低衰减频段。 展开更多
关键词 煤矿巷道 巷道壁粗糙度 电波传播 多波模模型 低衰减频段
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矿井巷道AF协作通信系统建模及信道容量优化 被引量:1
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作者 翟文艳 孙彦景 +2 位作者 徐钊 李松 徐岩 《太原理工大学学报》 CAS 北大核心 2015年第5期604-610,共7页
针对矿井巷道复杂受限环境中电磁波传播多径衰落问题,基于多波模信道模型,建立了矿井巷道放大转发(amplifying-and-forwarding,AF)协作通信系统模型,分别推导出矿井巷道单中继和多中继AF协作通信系统的信道容量公式。考虑矿井巷道内的... 针对矿井巷道复杂受限环境中电磁波传播多径衰落问题,基于多波模信道模型,建立了矿井巷道放大转发(amplifying-and-forwarding,AF)协作通信系统模型,分别推导出矿井巷道单中继和多中继AF协作通信系统的信道容量公式。考虑矿井巷道内的本质安全要求,在系统总功率和各节点功率双重受限的条件下,以信道容量为优化准则,分别提出了矿井巷道AF协作通信系统单中继和多中继环境的功率分配方法,并进行了仿真比较。实验证明,本方法能够显著提升系统的信道容量;系统总功率的大小影响功率分配方法对信道容量的优化效果和优化幅度:在一定总功率范围内,功率分配方法对信道容量的优化效果随着总功率的增加而减小,功率分配方法对信道容量的优化幅度随着总功率的增加而增加。 展开更多
关键词 矿井巷道 多波模 协作通信 放大转发 信道容量 功率分配
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粗糙度对矩形巷道电磁波传播特性影响的仿真 被引量:5
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作者 张冰丽 成凌飞 +1 位作者 高慧 贾琳 《计算机仿真》 CSCD 北大核心 2016年第2期216-220,339,共6页
在多波模损耗模型基础上,为了确定掠射角的大小,采用作图分析的方法,得出结论:在反射过程中,各波模在两侧壁和上下两壁的掠射角保持不变,且掠射角分别等于水平入射面和垂直入射面的初始入射角,同时推导验证了各模次波模的反射次数。不... 在多波模损耗模型基础上,为了确定掠射角的大小,采用作图分析的方法,得出结论:在反射过程中,各波模在两侧壁和上下两壁的掠射角保持不变,且掠射角分别等于水平入射面和垂直入射面的初始入射角,同时推导验证了各模次波模的反射次数。不同于以往只考虑频率因素,为了从频率和粗糙度方差σ2两个方面定量的研究巷道壁粗糙对传播损耗及粗糙度损耗的影响,运用公式推导及仿真的方法得出结论:粗糙度损耗和传播损耗随粗糙度的增加而增大;粗糙对传播损耗的影响随传播频率的增大而增大。在上述结论的基础上提出了频率拐点的概念并通过仿真分析得出结论:当频率小于频率拐点时,传播损耗随着频率的升高而减小,大于频率拐点时,传播损耗随着频率的升高而增大;频率拐点的大小与粗糙度有关,与其它因素无关。频率拐点的确定,有助于判断传播损耗的变化趋势,为井下无线传输的最佳频率提供理论依据。 展开更多
关键词 矩形巷道 电磁波传播 粗糙度 频率拐点 多波模
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氢氧旋转爆震传播特性研究 被引量:2
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作者 范良忠 史强 +2 位作者 林伟 王家森 聂万胜 《推进技术》 EI CAS CSCD 北大核心 2022年第11期236-245,共10页
为揭示基于氢氧推进剂的旋转爆震火箭发动机的应用潜力,在环形燃烧室内开展了氢气/氧气旋转爆震试验,并基于OpenFOAM代码进行了三维非预混高保真数值仿真工作。试验研究表明,燃烧室内存在6个以上同向旋转爆震波,频率约为36.6kHz。同等... 为揭示基于氢氧推进剂的旋转爆震火箭发动机的应用潜力,在环形燃烧室内开展了氢气/氧气旋转爆震试验,并基于OpenFOAM代码进行了三维非预混高保真数值仿真工作。试验研究表明,燃烧室内存在6个以上同向旋转爆震波,频率约为36.6kHz。同等工况的仿真结果显示,爆震波经过一系列对撞调整过程后演化为7个同向传播的爆震波,波头高度约7mm。稳定阶段的平均频率为45.7kHz,传播速度为Chapman-Jouguet爆震速度的87%。传播过程中爆震波保持着波阵面、接触面、滑移线等典型结构。然而,新鲜混气在接触面发生了显著爆燃,这可能导致氢氧旋转爆震发动机的性能损失。 展开更多
关键词 旋转爆震 氢气/氧气 非预混进气 爆燃 多波模
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Robust edge detection based on stationary wavelet transform 被引量:3
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作者 章国宝 刘泉 《Journal of Southeast University(English Edition)》 EI CAS 2006年第2期218-221,共4页
By combining multiscale stationary wavelet analysis with fuzzy c-means, a robust edge detection algorithm is presented. Based on the translation invafiance built in multiscale stationary wavelet transform, components ... By combining multiscale stationary wavelet analysis with fuzzy c-means, a robust edge detection algorithm is presented. Based on the translation invafiance built in multiscale stationary wavelet transform, components in different transformed sub-images corresponding to a pixel are employed to form a feature vector of the pixel. All the feature vectors are classified with unsupervised fuzzy c-means to segment the image, and then the edge pixels are checked out by the Canny detector. A series of images contaminated with different intensive Gaussian noises are used to test the novel algorithm. Experiments show that fairly precise edges can be checked out robustly from those images with fairly intensive noise by the proposed algorithm. 展开更多
关键词 edge detection stationary wavelet multiscale analysis fuzzy c-means
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矿井空巷道无线信道特性分析与仿真 被引量:1
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作者 姚述福 余伟健 《矿业工程研究》 2020年第2期73-78,共6页
随着现代通信技术的快速发展,矿井中通信方式也由原来的有线通信向无线通信转变.随着近些年我国矿产资源的不断开发与利用,建设安全可靠的矿井通信系统成为了矿产高效生产和井下救援的必要措施.根据电磁波在矿井巷道中的传播特征,介绍... 随着现代通信技术的快速发展,矿井中通信方式也由原来的有线通信向无线通信转变.随着近些年我国矿产资源的不断开发与利用,建设安全可靠的矿井通信系统成为了矿产高效生产和井下救援的必要措施.根据电磁波在矿井巷道中的传播特征,介绍了经典电磁波传播相关方程及多波模传输理论.为了简化巷道模型,重点分析了空矩形矿井巷道中的电磁波传播形式,并对巷道中存在的倾斜损耗、粗糙损耗等相关损耗进行了分析,最后通过MATLAB仿真分析,选择矿井巷道中适合电磁波传输的最佳频率段. 展开更多
关键词 无线通信 电磁波传播特征 多波模传输理论 矩形矿井巷道
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Multiple Kalman filters model with shaping filter GPS real-time deformation analysis 被引量:6
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作者 李丽华 彭军还 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第11期3674-3681,共8页
In order to detect the deformation in real-time of the GPS time series and improve its reliability, the multiple Kalman filters model with shaping filter was proposed. Two problems were solved: firstly, because the GP... In order to detect the deformation in real-time of the GPS time series and improve its reliability, the multiple Kalman filters model with shaping filter was proposed. Two problems were solved: firstly, because the GPS real-time deformation series with a high sampling rate contain coloured noise, the multiple Kalman filter model requires the white noise, and the multiple Kalman filters model is augmented by a shaping filter in order to reduce the colored noise; secondly, the multiple Kalman filters model with shaping filter can detect the deformation epoch in real-time and improve the quality of GPS measurements for the real-time deformation applications. Based on the comparisons of the applications in different GPS time series with different models, the advantages of the proposed model were illustrated. The proposed model can reduce the colored noise, detect the smaller changes, and improve the precision of the detected deformation epoch. 展开更多
关键词 multiple Kalman filters model Kalman filter shaping filter deformation detection
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Tapered Multimode Interference Combiners for Coherent Receivers 被引量:1
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作者 武志刚 张伟刚 +5 位作者 王志 开桂云 袁树中 董孝义 宇高胜之 和田恭雄 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第2期328-335,共8页
A new tapered multimode interference (MMl)-based coherent lightwave combiner is reported. A comprehensive theoretical analysis of mode behaviors in the tapered MMI waveguide is presented, and the output characterist... A new tapered multimode interference (MMl)-based coherent lightwave combiner is reported. A comprehensive theoretical analysis of mode behaviors in the tapered MMI waveguide is presented, and the output characteristics of the tapered MMI combiners with various structures are demonstrated. The combiner is fabricated on a silicon-on-insulator (SO1) substrate. Due to its advantages of having no end-facet reflection,easy extension to a multi-port configuration, high tolerance for fabrication errors, and compact size, the tapered MMI is a good candidate for a coherent lightwave combiner to be used in large-scale photonic integrated circuits. 展开更多
关键词 integrated optics multimode interference COMBINER SILICON-ON-INSULATOR
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A 900MHz CMOS PLL/Frequency Synthesizer Initialization Circuit 被引量:1
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作者 赵晖 任俊彦 章倩苓 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2003年第12期1244-1249,共6页
A 900MHz CMOS PLL/frequency synthesizer using current-adjustable charge-pump circuit and on-chip loop filter with initialization circuit is presented.The charge-pump current is insensitive to the changes of temperatur... A 900MHz CMOS PLL/frequency synthesizer using current-adjustable charge-pump circuit and on-chip loop filter with initialization circuit is presented.The charge-pump current is insensitive to the changes of temperature and power supply.The value of the charge-pump current can be changed by switches,which are controlled by external signals.Thus the performance of the PLL,such as loop bandwidth,can be changed with the change of the charge-pump current.The loop filter initialization circuit can speed up the PLL when the power is on.A multi-modulus prescaler is used to fulfill the frequency synthesis.The circuit is designed using 0.18μm,1.8V,1P6M standard digital CMOS process. 展开更多
关键词 PLL charge-pump loop filter multi-modulus prescaler
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SOI Waveguides Fabricated by Wet-Etching Method
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作者 王小龙 严清峰 +2 位作者 刘敬伟 陈少武 余金中 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2003年第10期1025-1029,共5页
SOI waveguides fabricated by wet-etching method are demonstrated.The single mode waveguide and 1×2 3dB MMI splitter are analyzed and designed by three dimensional beam propagation method to correct the error of e... SOI waveguides fabricated by wet-etching method are demonstrated.The single mode waveguide and 1×2 3dB MMI splitter are analyzed and designed by three dimensional beam propagation method to correct the error of effective index method and guided mode method.The devices are fabricated.Excellent performances,such as low propagation loss of -1.37dB/cm,low excess loss of -2.2dB,and good uniformity of 0.3dB,are achieved. 展开更多
关键词 SOI wet-etching multimode interference single mode waveguide
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An interacting multiple model-based two-stage Kalman filter for vehicle positioning 被引量:2
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作者 徐启敏 李旭 +1 位作者 李斌 宋向辉 《Journal of Southeast University(English Edition)》 EI CAS 2017年第2期177-181,共5页
To address the problem that a general augmented state Kalman filter or a two-stage Kalman filter cannot achieve satisfactory positioning performance when facing uncertain noise of the micro-electro-mechanical system(... To address the problem that a general augmented state Kalman filter or a two-stage Kalman filter cannot achieve satisfactory positioning performance when facing uncertain noise of the micro-electro-mechanical system(MEMS) inertial sensors, a novel interacting multiple model-based two-stage Kalman filter(IMM-TSKF) is proposed to adapt to the uncertain inertial sensor noise. Three bias filters are developed based on different noise characteristics to cover a wide range of noise levels. Then, an accurate estimation of biases is calculated by the interacting multiple model algorithm to correct the bias-free filter. Thus, the vehicle positioning system can achieve good performance when suffering from uncertain inertial sensor noise. The experimental results indicate that the average position error of the proposed IMMTSKF is 25% lower than that of the general TSKF. 展开更多
关键词 interacting multiple model(IMM) two-stage filter uncertain noise vehicle positioning
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Design and Fabrication of Ultracompact 3-dB MMI Coupler in Silicon-on-Insulator 被引量:1
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作者 严清峰 余金中 刘忠立 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2003年第2期133-136,共4页
An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is... An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is ~40% shorter in length.The device exhibits uniformity of 1 3dB and excess loss of 2 5dB. 展开更多
关键词 multimode interference coupler line tapered waveguide silicon on insulator
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An Efficient MMI SOI Splitter with Multimode Input/Output Waveguides
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作者 方青 贺月娇 +2 位作者 辛红丽 李芳 刘育梁 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第2期276-280,共5页
A 1×8 multimode interference power splitter with multimode input/output waveguides in SOI material is designed by the beam propagation method and fabricated by the inductive coupled plasma etching technology for... A 1×8 multimode interference power splitter with multimode input/output waveguides in SOI material is designed by the beam propagation method and fabricated by the inductive coupled plasma etching technology for use in fiber optics communication systems.The fabricated device exhibits low loss and good coupling uniformity.The excess loss is lower than 0 8dB,and the uniformity is 0 45dB at the wavelength of 1550nm.Moreover,the polarization dependent loss is lower than 0 7dB at 1550nm.The device size is only 2mm×10mm. 展开更多
关键词 multimode interference power splitter SOI multimode input/output waveguides
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A Novel Multi-Stage Interpolation Filter Design Technique for High-Resolution Σ-Δ DAC 被引量:2
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作者 陈润 刘力源 李冬梅 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第11期1735-1741,共7页
This paper presents an efficient way to implement an interpolation filter in a 20bit ∑-△ DAC with an oversampling ratio of 128. A multistage structure is used to reduce the complexity of filter coefficients and the ... This paper presents an efficient way to implement an interpolation filter in a 20bit ∑-△ DAC with an oversampling ratio of 128. A multistage structure is used to reduce the complexity of filter coefficients and the fi- nite word length effect. A novel method based on mixed-radix number representation is proposed to realize a poly- phase multiplier-free half-band subfilter with a high resolution. This approach reduces the complexity of the con- trol system and saves chip area dramatically. The IC is realized in a standard 0.13μm CMOS process and the inter- polation filter occupies less than 0.63mm^2 . This realization has desirable properties of regularity with simple hard- ware devices which are suitable for VLSI and can be applied to many other high resolution data converters. 展开更多
关键词 interpolation filter mixed-radix MULTISTAGE ∑-△ DAC
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Maneuvering target tracking using threshold interacting multiple model algorithm
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作者 徐迈 山秀明 徐保国 《Journal of Southeast University(English Edition)》 EI CAS 2005年第4期440-444,共5页
To avoid missing track caused by the target maneuvers in automatic target tracking system, a new maneuvering target tracking technique called threshold interacting multiple model (TIMM) is proposed. This algorithm i... To avoid missing track caused by the target maneuvers in automatic target tracking system, a new maneuvering target tracking technique called threshold interacting multiple model (TIMM) is proposed. This algorithm is based on the interacting multiple model (IMM) method and applies a threshold controller to improve tracking accuracy. It is also applicable to other advanced algorithms of IMM. In this research, we also compare the position and velocity root mean square (RMS) errors of TIMM and IMM algorithms with two different examples. Simulation results show that the TIMM algorithm is superior to the traditional IMM alzorithm in estimation accuracy. 展开更多
关键词 maneuvering target tracking Kalman filter interacting multiple model (IMM) threshold interacting multiple model (TIMM)
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A molding method to fabricate the waveguide multilayer card 被引量:1
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作者 ZHOU Wang-ren LIANG Zhong-cheng GU Min-fen 《Optoelectronics Letters》 EI 2008年第2期153-154,共2页
Waveguide multilayer optical card (WMOC) is a new kind of three-dimensional storage device. A method of fabricating the WMOC using the molding technique is introduced in this paper. The fabrication of WMOC mainly incl... Waveguide multilayer optical card (WMOC) is a new kind of three-dimensional storage device. A method of fabricating the WMOC using the molding technique is introduced in this paper. The fabrication of WMOC mainly includes data writing with hot embossing method and multilayer bonding with PDMS material. The structure of the WMOC is consisted with Polycarbonate (PC) as the core layer material and Polydimethylsiloxane (PDMS) as cladding layer. The experimental results demonstrate that the molding fabrication method is feasible and effective. 展开更多
关键词 波导 多层卡 制模方法 结构
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Adaptive load forecasting of the Hellenic electric grid 被引量:1
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作者 S.Sp.PAPPAS L.EKONOMOU +2 位作者 V.C.MOUSSAS P.KARAMPELAS S.K.KATSIKAS 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第12期1724-1730,共7页
Designers are required to plan for future expansion and also to estimate the grid's future utilization. This means that an effective modeling and forecasting technique, which will use efficiently the information c... Designers are required to plan for future expansion and also to estimate the grid's future utilization. This means that an effective modeling and forecasting technique, which will use efficiently the information contained in the available data, is required, so that important data properties can be extracted and projected into the future. This study proposes an adaptive method based on the multi-model partitioning algorithm (MMPA), for short-term electricity load forecasting using real data. The grid's utilization is initially modeled using a multiplicative seasonal ARIMA (autoregressive integrated moving average) model. The proposed method uses past data to learn and model the normal periodic behavior of the electric grid. Either ARMA (autoregressive moving average) or state-space models can be used for the load pattern modeling. Load anomalies such as unexpected peaks that may appear during the summer or unexpected faults (blackouts) are also modeled. If the load pattern does not match the normal be-havior of the load, an anomaly is detected and, furthermore, when the pattern matches a known case of anomaly, the type of anomaly is identified. Real data were used and real cases were tested based on the measurement loads of the Hellenic Public Power Cooperation S.A., Athens, Greece. The applied adaptive multi-model filtering algorithm identifies successfully both normal periodic behavior and any unusual activity of the electric grid. The performance of the proposed method is also compared to that produced by the ARIMA model. 展开更多
关键词 Adaptive multi-model filtering ARIMA Load forecasting Measurements Kalman filter Order selection SEASONALVARIATION Parameter estimation
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Using interacting multiple model particle filter to track airborne targets hidden in blind Doppler 被引量:16
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作者 DU Shi-chuan SHI Zhi-guo +1 位作者 ZANG Wei CHEN Kang-sheng 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第8期1277-1282,共6页
In airborne tracking,the blind Doppler makes the target undetectable,resulting in tracking difficulties. In this paper,we studied most possible blind-Doppler cases and summed them up into two types:targets' intent... In airborne tracking,the blind Doppler makes the target undetectable,resulting in tracking difficulties. In this paper,we studied most possible blind-Doppler cases and summed them up into two types:targets' intentional tangential flying to radar and unintentional flying with large tangential speed. We proposed an interacting multiple model(IMM) particle filter which combines a constant velocity model and an acceleration model to handle maneuvering motions. We compared the IMM particle filter with a previous particle filter solution. Simulation results showed that the IMM particle filter outperforms the method in previous works in terms of tracking accuracy and continuity. 展开更多
关键词 Interacting multiple model Particle filter Blind Doppler
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A novel maneuvering multi-target tracking algorithm based on multiple model particle filter in clutters 被引量:2
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作者 胡振涛 Pan Quan Yang Feng 《High Technology Letters》 EI CAS 2011年第1期19-24,共6页
To solve the problem of strong nonlinear and motion model switching of maneuvering target tracking system in clutter environment, a novel maneuvering multi-target tracking algorithm based on multiple model particle fi... To solve the problem of strong nonlinear and motion model switching of maneuvering target tracking system in clutter environment, a novel maneuvering multi-target tracking algorithm based on multiple model particle filter is presented in this paper. The algorithm realizes dynamic combination of multiple model particle filter and joint probabilistic data association algorithm. The rapid expan- sion of computational complexity, caused by the simple combination of the interacting multiple model algorithm and particle filter is solved by introducing model information into the sampling process of particle state, and the effective validation and utilization of echo is accomplished by the joint proba- bilistic data association algorithm. The concrete steps of the algorithm are given, and the theory analysis and simulation results show the validity of the method. 展开更多
关键词 maneuvering multi-target tracking multiple model particle filter interacting multiple model IMM) joint probabilistic data association
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