Wavelet Shrinkage Denoising Using the Non-Negative Garrote

Abstract

In this article, we combine Donoho and Johnstone's wavelet shrinkage denoising technique (known as WaveShrink) with Breiman's non-negative garrote. We show that the non-negative garrote shrinkage estimate enjoys the same asymptotic convergence rate as the hard and the soft shrinkage estimates. Simulations are used to demonstrate that garrote shrinkage offers advantages over both hard shrinkage (generally smaller mean-square-error and less sensitivity to small perturbations in the data) and soft shrinkage (generally smaller bias and overall mean-square-error). The minimax thresholds for the non-negative garrote are derived and the threshold selection procedure based on Stein's unbiased risk estimate (SURE) is studied. We also propose a threshold selection procedure based on combining Coifman and Donoho's cycle-spinning and SURE. The procedure is called SPINSURE. We use examples to show that SPINSURE is more stable than SURE: smaller standard deviation and smaller range.     

An evaluation of the effects of three laryngeal lubricants on phonation threshold pressure (PTP)

Clinicians frequently offer advice to performers and voice-disordered patients aimed ostensibly to manipulate the water content and/or viscosity of the mucus blanket covering the vocal folds. To evaluate the relative effects of three potential laryngeal lubricants on phonatory function (ie, water, Mannitol--an osmotic agent, and Entertainer's Secret Throat Relief (Kli Corp., Carmel, IN)--a glycerin-based product), phonation threshold pressure (PTP) was measured in 18 healthy, vocally normal female participants twice before (baseline) and then four times after 2 ml of each substance were nebulized. PTP is the minimum subglottal pressure required to initiate vocal fold oscillation, and the lowering of PTP is assumed to correspond to physiologically more efficient phonation and reduced phonatory effort. Over a 3-week period, participants were tested on three separate occasions (at 1-week intervals). On each occasion, a different nebulized treatment was administered. PTP for both comfortable and high fundamental frequency productions was measured using an oral pressure-flow system (Perci-Sars, MicroTronics Corp., Chapel Hill, NC). Analysis of the results revealed that Mannitol, an agent that encourages osmotic water flux to the luminal airway surface, lowered PTP immediately after its administration (ie, p = 0.071, for high-pitched productions only). However, the duration of its PTP lowering effect was less than 20 minutes. The other two substances did not demonstrate any significant postadministration effect on PTP.     

Treatment of MZI sensor signal with an improved wavelet neighboring coefficients

In order to gain the wavelength drift of Mach–Zehnder interferometer (MZI) sensor system, achieve the measurement of ambient environment parameters precisely, so, need to treatment optical fiber sensing signal with noise. Firstly, introduce the method of neighborhood wavelet coefficient by analyzing the drawback of traditional wavelet de-noising methods. Secondly, an improved threshold is putted forward based on neighboring coefficients in this paper which is to overcome the shortcomings of traditional wavelet methods. Finally, the threshold function proposed by this paper deal with MZI sensing noisy signal together with improved threshold. The simulation result shows that the new method can get the better signal-to-noise ratios (SNR) and root of mean square error (MSE) simultaneously and gain the reconstruction signal of the higher correlation coefficient (CC). Compared with the soft and hard threshold method, its SNR increases by 2–4 db, and compared with NeighCoeff, its SNR improves by 1.2 db. The peak error is 1.6 pm. So, the system can meet the requirement of improving sensor detection precision.     

Development of a surface acoustic wave wireless and passive temperature sensor incorporating reflective delay line

based on optimal design on the core element of the sensor,a wireless and passive surface acoustic wave(SAW)temperature sensor integrated with ID Tag was presented.A reflective delay line,which consists of a transducer and eight reflectors on YZ LiNbO3 substrate.Was fabricated as the sensor element,in which,three reflectors were used for temperature sensing,and the other five were for the ID Tag using phase encoding.Single phase unidirectional transducers(SPUDTs)and shorted grating were used to structure the sAW device,leading to excellent signal to noise ratio(SNR).The performance of the SAW device was simulated by the coupling of modes(COM)prior to fabrication.Using the network analyzer,the response in time domain of the fabricated 434 MHz SAW sensor was characterized,the measured S11 agrees well with the simulated one,sharp reflection peaks,high signal/noise,and low spurious noise between the reflection peaks were observed.Using the radar system based on FSCW as the reader unit.the developed SAW temperature sensors were evaluated wirelessly.Excellent1 inearity and good resolution of士1℃ were observed.     

Current analysis of DC negative corona discharge in a wire-cylinder configuration at high ambient temperatures

To study the characteristics of DC negative corona discharge in a wire-cylinder configuration at an ambient temperature range of 350–850 °C, the I–V characteristics and the current composition are analyzed under different conditions. A simple method is proposed to determine the DC corona onset threshold voltage. At high ambient temperatures, in the DC negative corona discharge gap, some electrons are not attached to the electronegative gas molecules and move to the anode tube. Thus, these electrons form an electron current, which may account for most of the total discharging current. The ratio of the electron current to the total discharging current increases with increasing temperature. In a mixture of O₂ and N₂ and a mixture of CO₂ and N₂, the ratio of electron current increases with increasing N₂ content in the mixtures. The cathode material has little influence on the corona discharge characteristics at high ambient temperatures.     

基于LEACH路由协议的多跳节能路由算法

当无线传感器网络部设在不同环境中时,需要提出新的算法以适应特殊环境,减少节点能量消耗;算法针对LEACH路由算法的局限性,提出了一种适用网络覆盖范围较大,节点间距离较远,需要远距离传输的路由算法;本算法利用节点到基站的距离因素,修改簇头阈值信息;并利用簇头竞争重新设定簇头,使剩余能量较高的节点成为簇头;同时,运用多跳的方式传输数据,这样可以适应远距离传输;仿真结果表明,相对LEACH算法,算法将节点死亡时间推后了300~400轮,网络存活周期延长了400轮左右,很明显的减少了网络的能量消耗,延长了网络的生存周期和稳定性。     

随机化的Eigen模型研究

为了使Eigen模型能够更真实地描述物种的演化过程,将确定性Eigen模型改造成随机模型.以Eigen模型为理论框架,把基因序列中每一个位点的突变率看作一个高斯随机变量,从而导出随机性Eigen模型.对于此随机性Eigen模型,当突变率的涨落强度较小时,准物种的误差阈位置几乎没有改变,仍是个相变点;而当突变率的涨落强度变大时,误差阈由一个相变点变为一个转变区域.在真实的物种演化过程中,误差阈应是一个转变区域,而且在解决实际问题时应考虑该转变区域的上限.     

交通流突变点的无标度特征分析

交通流时间序列在不同时间尺度上具有不同的波动特征.为了分析交通流的突变特征,以一段实际的交通流量序列为研究对象进行实证研究.采用小波变换的方法求得交通流在不同尺度上的突变点,按照小波函数过零点数目将交通流的尺度划分为若干层次,并分析了交通流突变的层次性.计算表明:以突变点数目为测度时,在一定的尺度范围内,交通流在突变层次上的突变点数目满足自相似性特征.因此,交通流的突变在不同尺度上具有无标度性.     

-1不同温度生长DKDP晶体的性质

用点籽晶快速生长法在不同温度区间生长了四块氘含量60% DKDP晶体,观察了不同温度下晶体生长过程,同时测量了晶体的透过光谱、摇摆曲线和1053 nm激光损伤阈值。结果表明,在高温区间晶体生长外形优于低温生长的晶体。不同温区晶体的透过光谱并无明显变化,但是随着生长温度的降低,晶体的结构完整性变差,1053 nm激光损伤阈值降低。     

辐照激光能量对SiO2薄膜特性及结构的影响

 为了认识SiO2薄膜在激光辐照下的变化,本文以K9玻璃为基底,采用电子束热蒸发方法制备了SiO2薄膜,并将此组在相同实验条件下制备的薄膜加以不同能量的激光辐照,研究在激光辐照前后样片的透射率、折射率、消光系数、膜厚、表面形貌及激光损伤阈值（LIDT）的变化。结果表明,样片膜厚随激光能量的增加而减小,辐照激光能改善薄膜表面形貌,并使样片LIDT值提高,最终能使样片的LIDT值从16.96 J/cm2提高至18.8 J/cm2。