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Impact of welding equipment on power quality
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作者 Kovács Attila Molnár Judit Jármai Károly 《China Welding》 CAS 2024年第3期44-51,共8页
In an industrial facility,many electrical consumers can affect the quality of electricity.Therefore,the freedom from interference sources of these devices and equipment can be crucial for quality and uninterrupted ele... In an industrial facility,many electrical consumers can affect the quality of electricity.Therefore,the freedom from interference sources of these devices and equipment can be crucial for quality and uninterrupted electricity supply.Electric welding equipment is also a possible source of interference.The electrical harmonic injections created by welding equipment into the electrical network can affect the operation of other consumers connected to the given distribution points and cause unjustified overheating and shutdowns of some network components.The aim of the research is to analyse the current harmonic injection of welding equipment of different types and modes of operation connected to the internal distribution network of the industrial facility.The effectiveness of the active harmonic filter built into the welding equipment was also examined in the paper.The results showed that the built-in active harmonic filter of the DC045 laser welding equipment was ineffective because the total harmonic distortion(THD)was about three times the 8%allowed by IEEE 519−2022 standard.The current harmonic injection of MIG 320 and MM403 type welding equipment was more than five times the permissible value of 5%.The current harmonic distortion of the PLAS140 type plasma-jet cutter equipment was below the 5% value allowed in the standard,thus it complied with it.Based on the measurement results,it can be concluded that the use of protection against harmonics is also necessary for welding equipment.Finally,proposals were made in the paper to reduce the effect of harmonics. 展开更多
关键词 electrical transients harmonic distortion electrical network disturbances voltage breaks total harmonic distortion(THD)
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Persymmetric adaptive polarimetric detection of subspace range-spread targets in compound Gaussian sea clutter
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作者 XU Shuwen HAO Yifan +1 位作者 WANG Zhuo XUE Jian 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2024年第1期31-42,共12页
This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian mod... This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian model with different parameters,and the target is modeled as a subspace rangespread target model.The persymmetric structure is used to model the clutter covariance matrix,in order to reduce the reliance on secondary data of the designed detectors.Three adaptive polarimetric persymmetric detectors are designed based on the generalized likelihood ratio test(GLRT),Rao test,and Wald test.All the proposed detectors have constant falsealarm rate property with respect to the clutter texture,the speckle covariance matrix.Experimental results on simulated and measured data show that three adaptive detectors outperform the competitors in different clutter environments,and the proposed GLRT detector has the best detection performance under different parameters. 展开更多
关键词 sea clutter adaptive polarimetric detection compound Gaussian model subspace range-spread target persymmetric structure
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Research on Modulation Signal Denoising Method Based on Improved Variational Mode Decomposition
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作者 Canyu Mo Qianqiang Lin +1 位作者 Yuanduo Niu Haoran Du 《Journal of Electronic Research and Application》 2024年第1期7-15,共9页
In order to further analyze the micro-motion modulation signals generated by rotating components and extract micro-motion features,a modulation signal denoising algorithm based on improved variational mode decompositi... In order to further analyze the micro-motion modulation signals generated by rotating components and extract micro-motion features,a modulation signal denoising algorithm based on improved variational mode decomposition(VMD)is proposed.To improve the time-frequency performance,this method decomposes the data into narrowband signals and analyzes the internal energy and frequency variations within the signal.Genetic algorithms are used to adaptively optimize the mode number and bandwidth control parameters in the process of VMD.This approach aims to obtain the optimal parameter combination and perform mode decomposition on the micro-motion modulation signal.The optimal mode number and quadratic penalty factor for VMD are determined.Based on the optimal values of the mode number and quadratic penalty factor,the original signal is decomposed using VMD,resulting in optimal mode number intrinsic mode function(IMF)components.The effective modes are then reconstructed with the denoised modes,achieving signal denoising.Through experimental data verification,the proposed algorithm demonstrates effective denoising of modulation signals.In simulation data validation,the algorithm achieves the highest signal-to-noise ratio(SNR)and exhibits the best performance. 展开更多
关键词 Micro-motion modulation signal Variational mode decomposition Genetic algorithm Adaptive optimization
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Readout electronics for a high-resolution soft X-ray spectrometer based on silicon drift detector 被引量:3
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作者 Er-Lei Chen Chang-Qing Feng +4 位作者 Shu-Bin Liu Chun-Feng Ye Dong-Dong Jin Jian Lian Hui-Jun Hu 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第1期94-99,共6页
The readout electronics for a prototype soft X-ray spectrometer based on silicon drift detector(SDD),for precisely measuring the energy and arrival time of X-ray photons is presented in this paper.The system mainly co... The readout electronics for a prototype soft X-ray spectrometer based on silicon drift detector(SDD),for precisely measuring the energy and arrival time of X-ray photons is presented in this paper.The system mainly consists of two parts,i.e.,an analog electronics section(including a pre-amplifier,a signal shaper and filter,a constant fraction timing circuit,and a peak hold circuit)and a digital electronics section(including an ADC and a TDC).Test results with X-ray sources show that an energy dynamic range of 1-10 keV with an integral nonlinearity of less than 0.1%can be achieved,and the energy resolution is better than 160 eV @ 5.9 keV FWHM.Using a waveform generator,test results also indicate that time resolution of the electronics system is about 3.7 ns,which is much less than the transit time spread of SDD(<100 ns)and satisfies the requirements of future applications. 展开更多
关键词 Energy and time measurement SOFT X-ray detection Silicon DRIFT DETECTOR READOUT ELECTRONICS
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Optimization method of linear barrier coverage deployment for multistatic radar 被引量:2
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作者 LI Haipeng FENG Dazheng WANG Xiaohui 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2023年第1期68-80,共13页
To address the problem of building linear barrier coverage with the location restriction, an optimization method for deploying multistatic radars is proposed, where the location restriction splits the deployment line ... To address the problem of building linear barrier coverage with the location restriction, an optimization method for deploying multistatic radars is proposed, where the location restriction splits the deployment line into two segments. By proving the characteristics of deployment patterns, an optimal deployment sequence consisting of multiple deployment patterns is proposed and exploited to cover each segment. The types and numbers of deployment patterns are determined by an algorithm that combines the integer linear programming(ILP)and exhaustive method(EM). In addition, to reduce the computation amount, a formula is introduced to calculate the upper threshold of receivers’ number in a deployment pattern. Furthermore, since the objective function is non-convex and non-analytic, the overall model is divided into two layers concerning two suboptimization problems. Subsequently, another algorithm that integrates the segments and layers is proposed to determine the deployment parameters, such as the minimum cost, parameters of the optimal deployment sequence, and the location of the split point. Simulation results demonstrate that the proposed method can effectively determine the optimal deployment parameters under the location restriction. 展开更多
关键词 multistatic radar linear barrier coverage minimum deployment cost deployment sequence wireless sensor networks(WSNs)
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Manoeuvre decision-making of unmanned aerial vehicles in air combat based on an expert actor-based soft actor critic algorithm 被引量:2
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作者 Bo Li Shuangxia Bai +3 位作者 Shiyang Liang Rui Ma Evgeny Neretin Jingyi Huang 《CAAI Transactions on Intelligence Technology》 SCIE EI 2023年第4期1608-1619,共12页
The demand for autonomous motion control of unmanned aerial vehicles in air combat is boosted as taking the initiative in combat appears more and more crucial.Unmanned aerial vehicles inability to manoeuvre autonomous... The demand for autonomous motion control of unmanned aerial vehicles in air combat is boosted as taking the initiative in combat appears more and more crucial.Unmanned aerial vehicles inability to manoeuvre autonomously during air combat that features highly dynamic and uncertain manoeuvres of the enemy;however,limits their combat capabilities,which proves to be very challenging.To meet the challenge,this article proposes an autonomous manoeuvre decision model using an expert actor-based soft actor critic algorithm that reconstructs empirical replay buffer with expert experience.Specifically,the algorithm uses a small amount of expert experience to increase the diversity of the samples,which can largely improve the exploration and utilisation efficiency of deep reinforcement learning.And to simulate the complex battlefield environment,a one-toone air combat model is established and the concept of missile's attack region is introduced.The model enables the one-to-one air combat to be simulated under different initial battlefield situations.Simulation results show that the expert actor-based soft actor critic algorithm can find the most favourable policy for unmanned aerial vehicles to defeat the opponent faster,and converge more quickly,compared with the soft actor critic algorithm. 展开更多
关键词 artificial intelligence techniques autonomous drone deep neural networks
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Temperature-Triggered Hardware Trojan Based Algebraic Fault Analysis of SKINNY-64-64 Lightweight Block Cipher
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作者 Lei Zhu Jinyue Gong +1 位作者 Liang Dong Cong Zhang 《Computers, Materials & Continua》 SCIE EI 2023年第6期5521-5537,共17页
SKINNY-64-64 is a lightweight block cipher with a 64-bit block length and key length,and it is mainly used on the Internet of Things(IoT).Currently,faults can be injected into cryptographic devices by attackers in a v... SKINNY-64-64 is a lightweight block cipher with a 64-bit block length and key length,and it is mainly used on the Internet of Things(IoT).Currently,faults can be injected into cryptographic devices by attackers in a variety of ways,but it is still difficult to achieve a precisely located fault attacks at a low cost,whereas a Hardware Trojan(HT)can realize this.Temperature,as a physical quantity incidental to the operation of a cryptographic device,is easily overlooked.In this paper,a temperature-triggered HT(THT)is designed,which,when activated,causes a specific bit of the intermediate state of the SKINNY-64-64 to be flipped.Further,in this paper,a THT-based algebraic fault analysis(THT-AFA)method is proposed.To demonstrate the effectiveness of the method,experiments on algebraic fault analysis(AFA)and THT-AFA have been carried out on SKINNY-64-64.In the THT-AFA for SKINNY-64-64,it is only required to activate the THT 3 times to obtain the master key with a 100%success rate,and the average time for the attack is 64.57 s.However,when performing AFA on this cipher,we provide a relation-ship between the number of different faults and the residual entropy of the key.In comparison,our proposed THT-AFA method has better performance in terms of attack efficiency.To the best of our knowledge,this is the first HT attack on SKINNY-64-64. 展开更多
关键词 SKINNY-64-64 lightweight block cipher algebraic fault analysis Hardware Trojan residual entropy
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Cuckoo search algorithm-based optimal deployment method of heterogeneous multistatic radar for barrier coverage
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作者 LI Haipeng FENG Dazheng 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2023年第5期1101-1115,共15页
This paper proposes an optimal deployment method of heterogeneous multistatic radars to construct arc barrier coverage with location restrictions.This method analyzes and proves the properties of different deployment ... This paper proposes an optimal deployment method of heterogeneous multistatic radars to construct arc barrier coverage with location restrictions.This method analyzes and proves the properties of different deployment patterns in the optimal deployment sequence.Based on these properties and considering location restrictions,it introduces an optimization model of arc barrier coverage and aims to minimize the total deployment cost of heterogeneous multistatic radars.To overcome the non-convexity of the model and the non-analytical nature of the objective function,an algorithm combining integer line programming and the cuckoo search algorithm(CSA)is proposed.The proposed algorithm can determine the number of receivers and transmitters in each optimal deployment squence to minimize the total placement cost.Simulations are conducted in different conditions to verify the effectiveness of the proposed method. 展开更多
关键词 heterogeneous multistatic radar(HMR) arc barrier coverage minimum deployment cost optimal deployment sequence cuckoo search algorithm(CSA)
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编码的非相干混合DS—SFH MFSK调制扩频通信系统在部分带宽多频干扰时的性能分析 被引量:6
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作者 Yang Wenge 杨文革 费元春 《兵工学报》 EI CAS CSCD 北大核心 2001年第1期57-61,共5页
本文针对部分带宽多频干扰 ( partial band multitone jamming)信道环境下 ,MFSK调制非相干混合 DS- SFH扩频通信系统性能研究的基础上 ,对使用 RS( V,K)码和双 k卷积码等几种不同前向纠错信道编码的 MFSK调制非相干混合 DS- SFH扩频通... 本文针对部分带宽多频干扰 ( partial band multitone jamming)信道环境下 ,MFSK调制非相干混合 DS- SFH扩频通信系统性能研究的基础上 ,对使用 RS( V,K)码和双 k卷积码等几种不同前向纠错信道编码的 MFSK调制非相干混合 DS- SFH扩频通信系统性能进行了分析、计算和比较。同时分析和讨论了部分带宽噪声干扰、前向纠错编码等对系统性能的影响 ,得到一些重要结果。 展开更多
关键词 部分带宽多频干扰 混合扩频 MFSK 调制 前向纠错编码 编码 通信系统 非相干混合
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Mathematic principle of active jamming against wideband LFM radar 被引量:12
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作者 Shixian Gong Xizhang Wei +1 位作者 Xiang Li Yongshun Ling 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第1期50-60,共11页
The inherent mathematic principle of active jamming against the wideband linear frequency modulated(LFM) radar is investigated. According to different generation strategies, the active jamming methods are reclassifi... The inherent mathematic principle of active jamming against the wideband linear frequency modulated(LFM) radar is investigated. According to different generation strategies, the active jamming methods are reclassified into three groups, i.e.,non-coherent jamming(NCJ), convolution jamming(CJ) and multiplying jamming(MJ). Based on the classification, the mathematic principles of different active jamming groups are put forward, which describe the relationships between the modulated signals and the jamming results. The advantages and disadvantages of different groups are further analyzed, which provides a new perspective for the study of jamming/anti-jamming methods and a potential for engineers to integrate similar jamming methods into one jammer platform. The analyses and simulation results of some typical active jamming methods prove the validity of the proposed mathematics principle. 展开更多
关键词 linear frequency modulated(LFM) mathematic principle active jamming
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High heat loading performance of actively cooled W/Cu FGM-based components 被引量:5
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作者 Zhang-jian Zhou Jun Tan +3 位作者 Dan-dan Qu Hua Li Young-jin yum Hyun-woo Lim 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2011年第4期467-471,共5页
A functionally graded material-based actively water-cooled tungsten-copper mockup with a dimension of 30 mm×30 mm×25 mm was designed and fabricated by infiltration-brazing method.The thicknesses of the pure ... A functionally graded material-based actively water-cooled tungsten-copper mockup with a dimension of 30 mm×30 mm×25 mm was designed and fabricated by infiltration-brazing method.The thicknesses of the pure W layer and W/Cu graded layer were 2 and 3 mm,respectively.High heat flux tests were performed on the mockup using an e-beam device.There is no damage occurring on the joint after heat loading at 5 MW/m2.The temperature on the pure W surface is less than 500°C after irradiation for 100 s at 5 MW/m2,while the temperature on the brazing seam/copper surface is around 200°C. 展开更多
关键词 TUNGSTEN COPPER functionally graded materials thermal load
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Multi-target localization for bistatic MIMO radar in the presence of unknown mutual coupling 被引量:3
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作者 Zhidong Zheng Jianyun Zhang Yuebo Wu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第5期708-714,共7页
A decoupling-estimation signal parameters via rotarional invariance technique(ESPRIT) method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output(MIMO)... A decoupling-estimation signal parameters via rotarional invariance technique(ESPRIT) method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output(MIMO) radar.Two steps are carried out in this method.The decoupling operation between angle and mutual coupling estimates is realized by choosing the auxiliary elements on both sides of the transmit and receive uniform linear arrays(ULAs).Then the ESPRIT method is resilient against the unknown mutual coupling matrix(MCM) and can be directly utilized to estimate the direction of departure(DOD) and the direction of arrival(DOA).Moreover,the mutual coupling coefficient is estimated by finding the solution of the linear constrained optimization problem.The proposed method allows an efficient DOD and DOA estimates with automatic pairing.Simulation results are presented to verify the effectiveness of the proposed method. 展开更多
关键词 bistatic multiple-input multiple-output(MIMO) radar angle estimation mutual coupling auxiliary element estimation signal parameters via rotarional invariance technique(ESPRIT)
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Analytical Expressions of Dual-Frequency Plasma Diagnostic Theory 被引量:3
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作者 程立 时家明 许波 《Plasma Science and Technology》 SCIE EI CAS CSCD 2012年第1期37-39,共3页
Based on the fundamental ideas concerning microwave attenuation in plasma, we obtain a new expression of transmission attenuation of microwaves as a function of the incident wave frequency. And with reasonable hypothe... Based on the fundamental ideas concerning microwave attenuation in plasma, we obtain a new expression of transmission attenuation of microwaves as a function of the incident wave frequency. And with reasonable hypothesis, analytical forms of the electron density and the electron-neutral collision frequency are derived from the equations of the transmission attenuation of microwaves at two near frequencies. This method gives an effective and easy approach to diagnose the unmagnetized plasma. 展开更多
关键词 PLASMA diagnosis DUAL-FREQUENCY ATTENUATION electron density electron-neutral collision frequency
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Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application 被引量:4
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作者 Weihao TIE Cui MENG +4 位作者 Chengguang ZHAO Xiaogang LU Jun XIE Dan JIANG Zirang YAN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2019年第9期110-121,共12页
We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line(GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate,... We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line(GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters(rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a?>?90 k V RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m^-1 and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge. 展开更多
关键词 gyro-magnetic nonlinear transmission line (GNLTL) SHARPENING CHARACTERISTICS sub-nanosecond pulse high REPETITION rate
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Program evaluation and its application to equipment based on super-efficiency DEA and gray relation projection method 被引量:4
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作者 Linbing Tang Dong Guo +1 位作者 Jie Wu Qingmei Tan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第6期1037-1042,共6页
For the gray attributes of the equipment program and its difficulty to carry out the quantitative assessment of the equipment program information, the gray relation projection method is simply reviewed. Combining the ... For the gray attributes of the equipment program and its difficulty to carry out the quantitative assessment of the equipment program information, the gray relation projection method is simply reviewed. Combining the super-data envelopment analysis(DEA) model and the gray system theory, a new super-DEA for measuring the weight is proposed, and a gray relation projection model is established to rank the equipment programs. Finally, this approach is used to evaluate the equipment program. The results are verified valid and can provide a new way for evaluating the equipment program. 展开更多
关键词 index weight discriminate coefficient gray relation projection method program evaluation
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Radar group target recognition based on HRRPs and weighted mean shift clustering 被引量:7
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作者 GUO Pengcheng LIU Zheng WANG Jingjing 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第6期1152-1159,共8页
When range high-resolution radar is applied to target recognition,it is quite possible for the high-resolution range profiles(HRRPs)of group targets in a beam to overlap,which reduces the target recognition performanc... When range high-resolution radar is applied to target recognition,it is quite possible for the high-resolution range profiles(HRRPs)of group targets in a beam to overlap,which reduces the target recognition performance of the radar.In this paper,we propose a group target recognition method based on a weighted mean shift(weighted-MS)clustering method.During the training phase,subtarget features are extracted based on the template database,which is established through simulation or data acquisition,and the features are fed to the support vector machine(SVM)classifier to obtain the classifier parameters.In the test phase,the weighted-MS algorithm is exploited to extract the HRRP of each subtarget.Then,the features of the subtarget HRRP are extracted and used as input in the SVM classifier to be recognized.Compared to the traditional group target recognition method,the proposed method has the advantages of requiring only a small amount of computation,setting parameters automatically,and having no requirement for target motion.The experimental results based on the measured data show that the method proposed in this paper has better recognition performance and is more robust against noise than other recognition methods. 展开更多
关键词 CLUSTERING group target recognition high resolution range profile(HRRP) mean shift(MS)
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Determination of spatial resolution of plastic scintillation fiber array with a simple method 被引量:3
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作者 TANG Shibiao MA Qingli +1 位作者 YIN Zejie HUANG Huan 《Nuclear Science and Techniques》 SCIE CAS CSCD 2007年第2期111-114,共4页
The spatial resolution of a position sensitive gamma-ray detector configuration based on plastic scintillation fiber array was measured using a Monte Carlo simulation method. Both point spread function and modulation ... The spatial resolution of a position sensitive gamma-ray detector configuration based on plastic scintillation fiber array was measured using a Monte Carlo simulation method. Both point spread function and modulation transfer function (MTF) were presented. The factors that influence the spatial resolution were also discussed. The results of the simulation showed that the intrinsic spatial resolution was consistent with the size of the physical pixels and a few centimeters spatial resolution could be obtained under certain circumstances. 展开更多
关键词 塑料闪烁光纤阵 空间分辨率 测定 简单方法
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Improved Measurement Performance of Inorganic Elements in Coal by Laser-Induced Breakdown Spectroscopy Coupled with Internal Standardization 被引量:3
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作者 姚顺春 徐嘉隆 +1 位作者 白凯杰 陆继东 《Plasma Science and Technology》 SCIE EI CAS CSCD 2015年第11期938-943,共6页
Laser-induced breakdown spectroscopy was employed to determine the inorganic elements in coal. To improve the measurement's accuracy and precision, a new internal standardization scheme, which we named changed intern... Laser-induced breakdown spectroscopy was employed to determine the inorganic elements in coal. To improve the measurement's accuracy and precision, a new internal standardization scheme, which we named changed internal standardization, was compared with the traditional internal standardization and no internal standardization for the analysis of inorganic elements. The new internal standardization scheme used the atomic line of carbon at 247.86 nm and the molecular band of CN at 388.34 nm and C2 at 516.32 nm to normalize the lines of inorganic elements that were distributed in the same spectral channel. The performance of the utilization of the new internal standardization scheme was evaluated using a set of coal samples, including twenty calibration samples and five validation samples. The results show that the coefficients of determination R2 and the slope of calibration models coupled with changed internal standard- ization are better than that of the calibration models coupled with fixed internal standardization and no internal standardization. Moreover, the measurement accuracy and reproducibility of changed internal standardization for the analysis of five validation samples also yielded further improvement. The results that we obtained suggest that changed internal standardization could compensate for the matrix effects, as well as the influence of the difference in the spectral response of the light collection system. 展开更多
关键词 laser-induced breakdown spectroscopy COAL internal standardization inorganic elements
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A DATA MINING METHOD BASED ON CONSTRUCTIVE NEURAL NETWORKS 被引量:4
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作者 Wang Lunwen Zhang Ling 《Journal of Electronics(China)》 2007年第1期133-137,共5页
In this letter,Constructive Neural Networks (CNN) is used in large-scale data mining. By introducing the principle and characteristics of CNN and pointing out its deficiencies,fuzzy theory is adopted to improve the co... In this letter,Constructive Neural Networks (CNN) is used in large-scale data mining. By introducing the principle and characteristics of CNN and pointing out its deficiencies,fuzzy theory is adopted to improve the covering algorithms. The threshold of covering algorithms is redefined. "Extended area" for test samples is built. The inference of the outlier is eliminated. Furthermore,"Sphere Neighborhood (SN)" are constructed. The membership functions of test samples are given and all of the test samples are determined accordingly. The method is used to mine large wireless monitor data (about 3×107 data points),and knowledge is found effectively. 展开更多
关键词 Data mining Neural networks Constructive Neural Networks (CNN) Wireless monitoring
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Numerical Simulation of Ionospheric Electron Concentration Depletion by Rocket Exhaust 被引量:2
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作者 黄勇 时家明 袁忠才 《Plasma Science and Technology》 SCIE EI CAS CSCD 2011年第4期446-450,共5页
In terms of the diffusive process of the gases injected from rocket exhaust into the ionosphere and the relevant chemical reactions between the gases and the composition of ionosphere, the modifications in ionosphere ... In terms of the diffusive process of the gases injected from rocket exhaust into the ionosphere and the relevant chemical reactions between the gases and the composition of ionosphere, the modifications in ionosphere caused by the injected hydrogen and carbon dioxide gas from the rocket exhaust are investigated. The results show that the diffusive process of the injected gases at the ionospheric height is very fast, and the injected gases can lead to a local depletion of electron concentration in the F-region. Furthermore, the plasma 'hole' caused by carbon dioxide is larger, deeper and more durable than that by the hydrogen. 展开更多
关键词 ionospheric modification rocket exhaust ionospheric hole diffusion process
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