共查询到20条相似文献,搜索用时 62 毫秒
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本文结合小波包变换和离散余弦变换,提出了一种基于听觉模型的混合域自适应音频盲水印算法,在不引入听觉失真的前提下,实现了自适应的水印嵌入。算法首先对音频信号进行小波包分解,使得分解后的子带更接近人耳临界频带。其次对每个子带的小波包系数进行离散余弦变换,计算出子带掩蔽阈值。根据子带掩蔽阈值自适应的选取噪声敏感度小的音频段作为水印嵌入段,选取功率值低于掩蔽阈值的频域系数作为水印嵌入位置,同时采用噪声掩蔽比调整水印嵌入强度。二值水印图像通过量化索引调制的方法嵌入到音频信号的中低频系数中,提取水印时不需要原始音频载体。本算法在水印容量、不可感知性和鲁棒性之间达到了很好的平衡,水印容量在576.7bps到689.5bps之间,算法对添加噪声、重新量化、重新采样、低通滤波和MP3压缩均具有很好的鲁棒性。 相似文献
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为保证DCT域水印的鲁棒性,研究水印信号的嵌入位置非常必要.对音频载体,尽管有许多文献提出将水印嵌在中频系数或对听觉效果重要的系数上,但始终缺乏一个统一的方法.本文在DCT噪声信号模型研究的基础上,提出了一种新的音频水印嵌入位置选择策略和一个应用该策略的自适应音频水印算法.通过定义DCT系数的噪声敏感度,建立了水印嵌入位置和嵌入水印后的音频信号的听觉感知性之间的关系,根据音频水印的不可听性的要求选择最优的嵌入位置,然后调节水印强度来满足鲁棒性的要求,从而最大程度地保持音频水印的不可听性和鲁棒性,为解决音频水印嵌入过程中不可听性和鲁棒性之间的矛盾提供了一种策略.应用该策略,本文提出了一个自适应音频水印算法.实验证实了算法的鲁棒性. 相似文献
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一种心理声学模型的自同步音频数字水印 总被引:2,自引:2,他引:0
提出了一种基于心理声学模型的自同步音频水印算法。在掩藏水印信息的同时,嵌入一个同步信号.使水印具有自同步能力。根据人耳听觉系统的心理声学模型,将水印信号和同步信号嵌入到中低频子波系数中.嵌入强度由掩蔽闻值自适应控制。仿真实验证明了算法的不可觉察性和鲁棒性。 相似文献
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基于听觉掩蔽效应和小波变换的数字音频水印 总被引:7,自引:0,他引:7
提出了一种基于听觉掩蔽效应和小波变换相结合的音频数字水印算法。根据人耳听觉系统的掩蔽效应,计算载体音频信号的掩蔽阈值,利用小波变换将掩蔽门限映射到小波系数中,然后将水印信号嵌入到中低频子波系数中.嵌入强度由掩蔽阈值自适应控制。实验结果表明:该算法隐藏水印具有很强的掩蔽性;叠加了水印的音频信号对数据压缩、加噪、重采样、低通滤波等常用音频信号处理技术具有很好的鲁棒性。 相似文献
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一种新的扩频音频水印算法 总被引:5,自引:2,他引:3
音频水印提供了一种数字保密的方法,用来保护作者和版权所有者的权利。在本文中。基于扩频技术提出了一种新的音频水印算法.即应用音频的瞬时平均频率(IMF)来嵌入数字水印,其目标是最大限度的满足水印的不可觉察性和健壮性。本文算法对原始的音频信号进行短时傅立叶变换,从而估计出信号的加权瞬时平均频率(IMF)。基于心理声学模型的掩蔽特性。可以得出水印被要求的相应的声压级。根据这些结果调制产生一个依赖于信号的不可觉察的水印。本算法允许在5秒钟的音频信号中嵌入25位信息。实验结果表明本文算法对于常见的信号处理攻击包括滤波、MP3压缩和添加噪声具有很好的健壮性。 相似文献
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文中提出了一种基于离散小波变换的同步数字音频盲水印算法.嵌入的水印为视觉上可辨的二值图像.算法中引入了嵌入同步信号的思想,利用同步信号定位水印的嵌入位置,为了提高信号的鲁棒性,把同步信号与水印隐藏在DWT域的低频系数中;同时,检测水印时不需要原始音频.仿真实验表明:所提出的方法具有较强的鲁棒性和不可感知性,并能有效抵御各种常见攻击. 相似文献
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本文提出了一种基于离散小波变换的同步数字音频盲水印算法。嵌入的水印为视觉上可辨的二值图像。算法中引入了嵌入同步信号的思想,利用同步信号定位水印的嵌入位置。为了提高信号的鲁棒性,把同步信号与水印隐藏在DWT域的低频系数中。同时,检测水印时不需要原始音频。仿真实验表明,所提出的方法具有较强的鲁棒性和不可感知性,并能有效抵御各种常见攻击。 相似文献
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在音频信号中添加水印后能保持不可感知性,满足一定的水印容量且同时具有较好的鲁棒性,是数字音频水印研究领域中的一项重要课题.针对这一问题,提出一种基于范数的离散小波变换(Discrete Wavelet Transformation,DWT)域鲁棒音频水印算法.首先对音频信号分帧,然后对每帧信号进行6级DWT分解,并选取低频系数构造成两个向量,分别计算向量范数,通过量化向量范数实现嵌入水印的目的,保证水印的鲁棒性.此外,利用Arnold变换和Logistic混沌序列对水印进行置乱和加密,提高水印的安全性.仿真实验结果表明,所提算法的水印安全性高,能在平均信噪比为30.01 dB,水印容量为43.07 b·s-1的情况下,对添加噪声、低通滤波、重采样、重量化以及MP3压缩等各种常见的音频信号处理攻击具有良好的鲁棒性. 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