共查询到20条相似文献,搜索用时 78 毫秒
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为了提高电子对抗设备对辐射源的识别能力,采用小波包变换法提取信号的时频谱特征,并引入支持向量机完成对辐射源的分类。小波包变换对信号局部的时频特征具有较好的分辨率,支持向量机分类器结构简单、可获得全局优化、泛化能力强。仿真结果表明,基于支持向量机的辐射源分类方法的正确率优于传统算法。 相似文献
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基于二维小波变换的激光成像雷达目标识别算法 总被引:1,自引:0,他引:1
提出了基于二维小波变换的激光成像雷达目标识别算法,首先对激光成像雷达目标的距离像进行二维小波变换;然后从近似分量和细节分量中提取奇异值特征,利用遗传算法对支持向量机参数进行智能优化;最后应用支持向量机对三种地面目标进行识别.仿真实验表明,该方法与直接应用距离像奇异值特征进行识别的方法相比,在高载噪比20dB时的平均识别... 相似文献
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提出了一种基于离散曲波变换和支持向量机的掌纹识别方法.首先将所有掌纹样本图像和测试图像通过基于Wrapping的快速离散曲波变换进行分解,从而获得不同尺度、不同角度的曲波变换系数;掌纹重要特征信息包含在曲波变换分解系数中的低频系数中,因此将分解系数变换形成特征向量后作为特征参数送入支持向量机中进行学习训练;最后将训练好的支持向量机用于掌纹分类.基于香港理工大学Palmprint掌纹数据库进行了大量实验,实验结果证实所提方法的识别正确率相对优于小波变换方法和其它几种经典方法. 相似文献
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利用光纤布拉格光栅(FBG)构建传感器网络,结合小波变换、频谱分析和支持向量机分类算法,对碳纤维复合材料板低速冲击区域定位进行了研究。根据划分区域进行冲击试验,探索冲击区域与信号特征之间的关系。在对低速冲击信号进行小波变换去除基线干扰的基础上,采用傅里叶变换提出提取冲击信号幅频特性作为信号特征进行低速冲击区域定位识别的方法,将提取的信号幅频特性作输入、冲击区域类别作输出构建支持向量多分类机实现低速冲击区域定位识别。实验结果表明:在500mm×500mm×2mm的碳纤维复合材料板上对36个测试样本进行低速冲击区域定位识别,实现33个低速冲击区域准确定位,正确率达90%以上,低速冲击定位系统的区域识别精度为40mm×40mm,且每个区域定位时间小于1011ms。研究结果为碳纤维复合材料板的低速冲击区域定位检测提供了一种科学可靠的方法。 相似文献
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针对目前临床上对特发性、帕金森病、生理性等3种常见震颤误诊断的问题,本文提出了一种基于双谱分析和支持向量机识别3种不同类型震颤的新方法.首先测量3种震颤类型志愿受试者手震颤的加速度信号并分别对其用Hinich方法检验,发现该类信号具有非高斯、非线性特性,然后用适合处理该类信号的双谱分析方法提取手震颤加速度信号的双谱对角切片的特征信息,最后采用"一对一"和"一对多"两种多分类的支持向量机算法对受试人的手震颤特征进行分类.交叉验证表明"一对一"算法的平均分类正确率高于"一对多"算法,分类正确率最高达到93.13%.该方法为临床医生提供了辅助识别不同类型震颤的新途径. 相似文献
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提出了一种基于小波包的变换方法。该方法通过对不同脉内调制方式进行频带能量的提取,并引入支持向量机来完成对辐射源的分类。该小波包变换对信号局部的时频特征具有较好的分辨率。仿真结果表明,文中的小波包变换信号时频特征的分析精度优于传统算法。 相似文献
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High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET > PDMAT > TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center. 相似文献
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In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal (200) (2d = 0.4027 nm) is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line(w), the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line(x), the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines(y), the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line(z) in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line(q) in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution(λ/△ 2) is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy. 相似文献
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This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors. 相似文献
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YUXiao-hua XIANGYu-qun 《半导体技术》2005,30(2):30-32,37
An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB. 相似文献
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The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO>6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs. 相似文献
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Meihua Shen Wilfred Pau Nicolas Gani Jianping Wen Shashank Deshmukh Thorsten Lill Jian Zhang Hanming Wu Guqing Xing 《半导体技术》2004,29(8)
This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration. 相似文献
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White organic light-emitting devices based on fac tris(2- phenylpyridine) iridium sensitized 5,6,11,12-tetraphenylnap -hthacene 总被引:1,自引:0,他引:1
We have fabricated the white organic light-emitting devices (WOLEDs) based on 4,4' -bis(2,2 -diphenyl vinyl)-1,1' - biphenyl (DPVBi) and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene (rubrene). The device structure is ITO/2T-NATA (20 nm)/NPBX (20 nm)/CBP: x%Ir(ppy)3:0.5% rubrene (8 nm)/NPBX (5 nm)/DPVBi (30 nm)/Alq(30 nm)/LiF(0.5 nm)/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)3], acts as a yellow light-emitting layer, and N,N' -bis- (1-naphthyl)- N,N' -diphenyl -1, 1' -biphenyl-4,4' -diamine (NPBX) acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir (PPY)3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V. 相似文献
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Complete approach to automatic identification and subpixel center location for ellipse feature 总被引:1,自引:0,他引:1
XUE Ting WU Bin SUN Mei YE Sheng-hua 《光电子快报》2008,4(1):51-54
To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction. 相似文献
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We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network. 相似文献