电能质量扰动的Block-Thresholding去噪方法

提出一种基于block-thresholding阈值估计量的电能质量扰动小波去噪算法。在小波域,各个尺度携带信号信息的小波系数其分布具有"簇聚"性质,即大部分系数成簇聚集在信号突变位置。所提算法将各个尺度的小波系数分成若干块,针对各个块进行阈值处理;而不像传统的小波阈值去噪算法,如Donoho等提出的VisuShrink那样预先确定一个阈值,对所有小波系数逐项比较进行去留处理。将所提算法与传统阈值去噪方法进行比较研究,仿真和实验结果表明所提算法在全局适应性和空间适应性方面的优越性。

Research on fiber optic gyro signal de-noising based on wavelet packet soft-threshold

Gyro＇s drift is not only the main drift error which influences gyro＇s precision but also the primary factor that affects gyro＇s reliability. Reducing zero drift and random drift is a key problem to the output of a gyro signal. A three-layer de-nosing threshold algorithm is proposed based on the wavelet decomposition to dispose the signal which is collected from a running fiber optic gyro （FOG）. The coefficients are obtained from the three-layer wavelet packet decomposition. By setting the high frequency part which is greater than wavelet packet threshold as zero, then reconstructing the nodes which have been filtered out noise and interruption, the soft threshold function is constructed by the coefficients of the third nodes. Compared wavelet packet de-noise with forced de-noising method, the proposed method is more effective. Simulation results show that the random drift compensation is enhanced by 13.1%, and reduces zero drift by 0.052 6°/h.

An Improved Double-Threshold Method Based on Gradient Histogram

This paper analyzes the characteristics of the output gradient histogram and shortages of several traditional automatic threshold methods in order to segment the gradient image better. Then an improved double-threshold method is proposed, which is combined with the method of maximum classes variance, estimating-area method and double-threshold method. This method can automatically select two different thresholds to segment gradient images. The computer simulation is performed on the traditional methods and this algorithm and proves that this method can get satisfying result. Key words gradient histogram image - threshold selection - double-threshold method - maximum classes variance method CLC number TP 391. 41 Foundation item: Supported by the National Nature Science Foundation of China (50099620) and the Project of Chenguang Plan in Wuhan (985003062)Biography: YANG Shen (1977-), female, Ph. D. candidate, research direction: multimedia information processing and network technology.

Above-threshold ionization of hydrogen atom in chirped laser fields

Above-threshold ionization （ATI） of a hydrogen atom exposed to chirped laser fields is investigated theoretically by solving the time-dependent Schrodinger equation. By comparing the energy spectra, the two-dimensional momentum spectra, and the angular distributions of photoelectron for the laser pulses with different chirp rates, we show a very clear chirp dependence both in the multiphoton and tunneling ionization processes but no chirp dependence in the single-photon ionization. We find that the chirp dependence in the multiphoton ionization based ATI can be attributed to the excited bound states. In the single-photon and tunneling ionization regimes, the electron can be removed directly from the ground state and thus the excited states may not be very important. It indicates that the chirp dependence in the tunneling ionization based ATI processes is mainly due to the laser pulses with different chirp rates,

Sub-threshold micro-pulse diode laser treatment in diabetic macular edema： a Meta-analysis of randomized controlled trials

AIM：To examine possible differences in clinical outcomes between sub-threshold micro-pulse diode laser photocoagulation（SDM） and traditional modified Early Treatment Diabetic Retinopathy Study（mETDRS）treatment protocol in diabetic macuiar edema（DME）.METHODS：A comprehensive literature search using the Cochrane Collaboration methodology to identify RCTs comparing SDM with mETDRS for DME.The participants were type Ⅰ or type Ⅱ diabetes mellitus with clinically significant macuiar edema treated by SDM from previously reported randomized controlled trials（RCTs）.The primary outcome measures were the changes in the best corrected visual acuity（BCVA） and the central macuiar thickness（CMT） as measured by optical coherence tomography（OCT）.The secondary outcomes were the contrast sensitivity and the damages of the retina.RESULTS：Seven studies were identified and analyzed for comparing SDM（215 eyes） with mETDRS（210 eyes）for DME.There were no statistical differences in the BCVA after treatment between the SDM and mETDRS based on the follow-up：3mo（MD,-0.02;95% Cl,-0.12 to 0.09;P=0.77）,6mo（MD,-0.02;95% Cl,-0.12 to 0.09;P=0.75）,12mo（MD,-0.05;95% Cl,-0.17 to 0.07;P=0.40）.Likewise,there were no statistical differences in the CMT after treatment between the SDM and mETDRS in 3mo（MD,-9.92;95% Cl,-28.69 to 8.85;P=0.30）,6mo（MD,-11.37;95% Cl,-29.65 to 6.91;P=0.22）,12mo（MD,8.44;95% Cl,-29.89 to 46.77;P=0.67）.Three RCTs suggested that SDM laser results in good preservation of contrast sensitivity as mETDRS,in two different followup evaluations：3mo（MD,0.05;95% Cl,0 to 0.09;P=0.04） and 6mo（MD,0.02;95% Cl,-0.10 to 0.14;P=0.78）.Two RCTs showed that the SDM laser treatment did less retinal damage than that mETDRS did（OR,0.05;95% Cl,0.02 to 0.13;P〈0.01）.CONCLUSION：SDM laser photocoagulation shows an equally good effect on visual acuity,contrast sensitivity,and reduction of DME as compared to conventional mETDRS protocol with less retinal damage.

The Coulomb effect on a low-energy structure in above-threshold ionization spectra induced by mid-infrared laser pulses

We investigate the low-energy structure （LES） in the above-threshold ionization spectrum at a mid-infrared laser wavelength with a semiclassical model. Using a softened Coulomb potential （CP） and changing the softening parameter, we show that though the very low-energy structure （VLES） and high low-energy structure （HLES） are both due to the interaction between the ionic CP and the electron, the two structures have different physical mechanisms： the VLES can be attributed to the electron-ion Coulomb interaction at a rather small distance and the HLES is more likely to be ascribed to the electron-ion Coulomb interaction at a large distance.

Influence of Stress Ratio and Loading Condition on Near-threshold Fatigue Crack Growth Behaviour

Near-threshold fatigue crack propagation behaviour of a cold-worked copper tested with distinct fa- tigue testing systems under different stress ratios has been investigated.The emphasis was placed on the evaluation of crack closure effect as well as the effective fatigue threshold,It was found that the fatigue threshold for R=0 is higher than those for R=-1 and R=0.4,for which almost the same threshold value was derived.Compared with the conventional closure evaluation method,the pro- posed new closure evaluation method can generally interpret the dependence of the fatigue thresh- old on stress ratio and loading condition,and leads to a higher and relatively constant effective fa- tigue threshold of about 3 MPa·m^(1/2) for the cold-worked copper at different stress ratios and loading conditions.

Dependence of above-threshold ionization spectrum on polarization directions of two-color laser fields

Using the frequency-domain theory, we investigate the above-threshold ionization（ATI） process of an atom in twocolor laser fields. When both photon energies of the two-color laser fields are much smaller than the atomic ionization threshold, the ATI spectrum depends on the angle between the two lasers＇ polarization directions. While when the photon energy of one laser is comparable with or larger than the atomic ionization threshold, the ATI spectrum is independent of the angle, and only several dips appear at certain angles. By analyzing the contributions of different quantum channels, we find that, for the case that both frequencies of the two color lasers are low, the quantum interferences between the channels are strong, and hence the spectrum changes with the angle between the two lasers＇ polarization directions. While for the case that the frequency of one of the two color lasers is high, the contributions of the channels to the ATI spectrum decrease dramatically with increasing channel order, hence the interferences between the channels disappear, and the ATI spectrum has a step-like structure, which is independent of the angle between the two lasers＇ polarizations. These results can shed light on the study of the corresponding relation between classical and quantum mechanisms of the matter–laser interaction in high-frequency laser fields.

MICROFRACTOGRAPHY OF NEAR-THRESHOLD FATIGUE CRACK PROPAGATION IN DUAL-PHASE STEELS

SEM microfractography of near-threshold fatigue crack propagation were carried out in the dual-phase steels of 3 martensite morphologies and 6 volume fractions of martensite (V_m). All of them are featured by cyclic cleavage characteristics in near-threshold region,i.e.,main- ly controlled by mode Ⅱ stress.In the higher ΔK regions,the fracture surfaces are character- ized by mixed modes including cyclic cleavage facets,two types of secondary cracks and striations,etc..The roughness-induced crack closure of fracture surface is attributed primarily to extreme high fatigue crack growth threshold values.

MICROFRACTOGRAPHY OF NEAR-THRESHOLD FATIGUE CRACK GROWTH

The fracture surface micromorphology in the near-threshold FCG region was studied in LD-10 aluminum alloy and Ti-6Al-4V allov.The SEM examinations reveal that the frac- ture surface of both alloys at low crack growth rates(1×10^(-7)-1×10^(-5)mm/cycle)takes on a cyclic facet appearance.The typical morphologies were either sawtoothedfacets or terraced facets for LD-10 aluminum alloy and isolated island facets for Ti-6Al-4V alloy.The mech- anism of near-threshold fatigue crack growth is explicated on the basis of experimental ob- servations.

Angle-resolved spectra of the direct above-threshold ionization of diatomic molecule in IR + XUV laser fields

The direct above-threshold ionization(ATI) of diatomic molecules in linearly-polarized infrared and extreme ultraviolet(IR+XUV) laser fields is investigated by the frequency–domain theory based on the nonperturbative quantum electrodynamics. The destructive interference fringes on the angle-resolved ATI spectra, which are closely related to the molecular structure, can be well fitted by a simple predictive formula for any alignment of the molecular axis. By comparing the direct ATI spectra for monochromatic and two-color laser fields, we found that the XUV laser field can both raise the ionization probability and the kinetic energy of the ionized electron, while the infrared(IR) laser field can broaden the energy distribution of the ionized electron. Our results demonstrate that, by using IR+XUV two-color laser fields, the angle-resolved spectra of the direct ATI can image the structural information of molecules without considering the recollision process of the ionized electron.

Asymmetric structure of atomic above-threshold ionization spectrum in two-color elliptically polarized laser fields

According to the frequency-domain theory, we investigate the asymmetric structure of above-threshold ionization(ATI) spectrum of an atom in two-color elliptically polarized(EP) laser fields. When both laser fields are linearly polarized(LP), the spectrum shows that the multi-plateau structure is symmetric about the emitted angle of electron at π/2, while the spectrum becomes asymmetric and shifts rightwards with the increase of the EP degree of the IR laser field. Since the total ATI process is regarded as including direct ATI and the rescattering ATI, we analyze the spectrum structure of direct ATI and rescattering ATI separately. Using the saddle-point approximation, we find that for direct ATI, the fringes on the spectrum are mainly attributed to the fact that the ionization probability becomes very small when the direction of emitted electrons is perpendicular to the direction of the XUV laser polarization;while for the rescattering ATI, the interference fringes on the spectrum mainly come from the superposition of the waist structures on the spectra of all sub-channels.

Characterization of Fundamental Logics for the Sub-Threshold Digital Design

Digital circuits operating in the sub-threshold regime consume the least energy. The strict energy constraints are desired in the applications which work at the lowest possible supply voltage. On the other hand, the conventional design flow utilizes the technology library provided by the foundry with a fixed voltage boundary, which causes problems when the supply scales down to the sub-threshold regime. In this paper, we present a design methodology to characterize the existing cell library with Liberty NCX to facilitate the standard design flow. It is demonstrated in 0.13 μm complementary metal-oxide-semiconductor （CMOS） technology with the supply voltage of 300 mV.

Influence of multi-photon excitation on the atomic above-threshold ionization

Using the time-dependent pseudo-spectral scheme, we solve the time-dependent Schrodinger equation of a hydrogen- like atom in a strong laser field in momentum space. The intensity-resolved photoelectron energy spectrum in abovethreshold ionization is obtained and further analyzed. We find that with the increase of the laser intensity, the abovethreshold ionization emission spectrum exhibits periodic resonance structure. By analyzing the population of atomic bound states, we find that it is the multi-photon excitation of bound state that leads to the occurrence of this phenomenon, which is in fairly good agreement with the experimental results.

Semiclassical investigation of Coulomb focusing effects in atomic above-threshold ionization with elliptically polarized laser fields

We investigate atomic above-threshold ionization in elliptically polarized strong laser fields with a semiclassical approach.With increasing laser intensity,the Coulomb focusing（CF） effects are found to become stronger in both parallel and perpendicular directions with respect to the polarization plane.The dependence of CF effects on tunnel exit,initial transverse momentum distribution and laser electric field is analyzed.It was revealed that the effects of tunnel exit are most prominent with variation of the laser intensity,and the other two factors both play non-negligible roles.Our results provide a deeper insight to the recent experiments of Coulomb asymmetry[Shafir D,et al.,2013 Phys.Rev.Lett.111 023005 and Li M,et al,2013 Phys.Rev.Lett.111 023006].

Multi-Threshold Algorithm Based on Havrda and Charvat Entropy for Edge Detection in Satellite Grayscale Images

Automatic edge detection of an image is considered a type of crucial information that can be extracted by applying detectors with different techniques. It is a main tool in pattern recognition, image segmentation, and scene analysis. This paper introduces an edge-detection algorithm, which generates multi-threshold values. It is based on non-Shannon measures such as Havrda & Charvat’s entropy, which is commonly used in gray level image analysis in many types of images such as satellite grayscale images. The proposed edge detection performance is compared to the previous classic methods, such as Roberts, Prewitt, and Sobel methods. Numerical results underline the robustness of the presented approach and different applications are shown.

Hormesis has emerged as a more common and fundamental dose-response model than the threshold or linear-no-threshold(LNT) models

在回顾传统的有阈和线性无阈的剂量-反应关系的基础上,分析此类该模型被毒理学领域认同的主要原因和其在预测低剂量效应中的缺陷,进而提出了高剂量接触呈现抑制效应,而低剂量却呈现促进或刺激作用这一全面的激效兴奋性剂量-反应关系,弥补了现有模型的不足,并充分论证这种激效性剂量-反应关系在不同种属、接触因素和生物学终点中的普遍性,并探讨了不同物质的激效兴奋作用的可能机制以及激效兴奋模型的三大优点,最后提出了激效模型谋求广泛接受的现实困难和发展趋势。

A time-over-threshold technique for PMT signals processing

A novel front-end circuit designed for PMT signals processing considering the solution of "Time Walk" correction is discussed in this paper. We are trying to apply the TOT (Time over Threshold) technique to our research. Different from traditional ways, where amplitude is measured, time width is measured for slew correction here, which takes the advantage of TDC. Expensive fast ADCs are abandoned and the whole time measurement electronics design becomes more effective and economical. Test boards have been developed and a convenient method is introduced to evaluate our TOT technique. Results have shown that a 10ps slew correction resolution is achieved throughout the amplitude range from -108mV to -2000mV for negative signals of both 5 ns leading and trailing edge with 10 ns 50%-50% pulse width.

Genuine (k,m)-Threshold Controlled Teleportation and Multipartite Entanglement

我们求婚真( k ， m )为经由多粒子的控制远距传物的阀值控制计划纠缠了状态，在到接收装置(鲍勃)的从一个发送者(艾莉斯)的一个量状态的远距传物在 m 监督人的控制下面以便这些监督人的 k ( k m )或更多能帮助跳的地方，恢复转移状态。由建设，我们的量隧道的任何人是任何二部分是无法分开的一个真多国参加的纠缠的状态。他们的性质著名 GHZ， W，和线性簇状态与那些被作比较并且形成对照，并且也，几个另外的真多国参加的纠缠的状态最近在文学介绍了。

Adaptive Dual-Threshold Edge Detection Based on Wavelet Transform

In order to solve the problems of local maximum modulus extraction and threshold selection in the edge detection of finite resolution digital images, a new wavelet transform based adaptive dual threshold edge detection algorithm is proposed. The local maximum modulus is extracted by linear interpolation in wavelet domain. With the analysis on histogram, the image is filtered with an adaptive dual threshold method, which effectively detects the contours of small structures as well as the boundaries of large objects. A wavelet domain's propagation function is used to further select weak edges. Experimental results have shown the self adaptivity of the threshold to images having the same kind of histogram, and the efficiency even in noise tampered images.