集中质量对不对称波形成的影响研究

采用 Rayleigh- Ritz法初步计算了集中质量对四边简支边界条件下的矩形板振型的影响 ,由计算结果绘制了矩形板的前两阶振型 ,并采用有限元法与计算结果进行了对比。分析表明 ,附加质量能导致波形的不对称且此不对称的振型波形主要是由两相邻阶的模态耦合而成 ,为压电驱动中不对称波的形成与作用的进一步研究奠定了基础。

额叶α波不对称与抑郁症自杀行为关系

目的通过对比有、无自杀行为抑郁症患者额叶α波不对称(frontal alpha asymmetry,FAA)指标,了解抑郁症患者FAA特征与抑郁症患者自杀行为的关系。方法纳入56例抑郁症患者,根据既往是否实施过自杀行为分为有自杀行为组(16例)、无自杀行为组(40例)。收集被试者的一般资料,使用脑电图检测FAA,评估贝克自杀意念量表(Beck scale for suicide ideation,BSS)。结果有、无自杀行为组抑郁症患者性别、年龄、受教育程度、汉密尔顿抑郁量表评分、汉密尔顿焦虑量表评分差异无统计学意义(P>0.05)。有、无自杀行为组BSS自杀意念评分差异无统计学意义(P>0.05),BSS自杀风险评分差异有统计学意义(43.62±19.81 vs.27.78±21.90,P=0.015)。有、无自杀行为组FP1/FP2位置FAA差异有统计学意义[0.06(-0.05,0.14)vs.0.16(0.06,0.32),P=0.006]。自杀行为与FP1/FP2位置FAA负相关(r=-0.349,P=0.008)。logistic回归分析显示抑郁症患者自杀行为与FP1/FP2位置FAA的关联有统计学意义(OR=0.008,P=0.024)。结论有自杀行为史的抑郁症患者左前额叶皮质活动减弱、右前额叶皮质活动增强。

广义Camassa-Holm方程的不对称孤立波和不对称扭波的存在性

利用动力系统定性理论和分支方法研究广义Camassa-Holm方程的行波.通过关键的分支值得到相应平面系统的相图,从而给出孤立波和扭波存在的充分条件;并且发现得到的孤立波和扭结波是不对称的,这与传统的对称孤立波和对称扭波是不一样的.

不对称式斩波放大的波形研究

本文以直流信号为例，研究了不对称式斩波方案，所得的交流抽样信号含有原来信号的全部信息，并具有传输效率高，抗干扰能力强的优点。

Peak Profile Analysis in High Field Asymmetric Wave Ion Mobility Spectrometry

High field asymmetric wave ion mobility spectrometry （FAIMS） is a powerful tool to detect and characterize gas-phase ions, while the unsolvable partial differential equation of ions moving in ion drift tube poses a big challenge to FAIMS spectral peak analysis. In this work, a universal and effective model of FAIMS spectral peak profile has been proposed by introducing ion trajectory and loss height. With this model, the influence of the structure of ion drift tube, dispersion voltages, compensation voltages, and carrier gas flow rate on the FAIMS spectral peak characteristics like peak shape, full width at half maximum and peak height is analyzed and discussed. The results show that the influence of different factors on the FAIMS spectral peak profile can be qualitatively described by the model which agrees with the experimental data.

Generation and detection of squeezed state

Soliton amplitude squeezed state is obtained and dctected by using asymmetric Sagnac interferometer and balanced homodyne detecting system. An improved photo detector circuit for quantum state detection is introduced. The circuit has a bandwidth of 10MHz and the saturation power is about 19 mW. A maximum photocurrent noise reduction of 1.1 dB below the shot noise is achieved. Taking the detection efficiency into account,the squeezing will be about 1.5 dB.

An Extended Method for Constructing Travelling Wave Solutions to Nonlinear Partial Differential Equations

In this paper, an extended method is proposed for constructing new forms of exact travelling wave solutions to nonlinear partial differential equations by making a more general transformation. For illustration, we apply the method to the asymmetric Nizhnik-Novikov-Vesselov equation and the coupled Drinfel＇d-Sokolov-Wilson equation and successfully cover the previously known travelling wave solutions found by Chen＇s method .

Theoretical and experimental investigation on nonlinear interaction among wave groups

Wave group is important in ocean wave theory and applications. In the past, nonlinear interaction among wave groups has been studied on the basis of the nonlinear Sehrrdinger equation. Using this theoretical approach, we found that the nonlinear interaction among wave groups causes asymmetry in the shape of the wave envelope （steeper in the front of the curve of the envelope）. An important consequence of this asymmetry is that the highest wave in a wave group appears one individual wave length ahead of the center of the wave group. Further results show that the degree of envelope asymmetry increases with increasing spectral width and the wave steepness. This theoretical analysis has been supplemented by a systematic experimental study of wind waves. Laboratory and some open sea wave data were analyzed. The results show that the shape of the wind wave envelope of wind waves has the same asymmetry predicted by the theoretical approach. The observed degree of deformation of the envelope also increases with increasing spectral width and the wave steepness as predicted by theory. These conclusions have important ramifications for practical applications of ocean wave theory.

Skulls Symmetry of ＂White Rasquera＂ Goat

Three common categories of bilateral asymmetry have been described： directional asymmetry, antisymmetry, and FA （fluctuating asymmetry）. FA is the most subtle of the three types of asymmetry, and differs from the patterns of the others in that paired structures tend to be symmetric in size. The analysis of FA allows to estimate the influence of stress factors on animal development and enables evaluation of resistance to stress. The aim of this work was to estimate the symmetry of skulls of a contemporary pure goat breed, as there is currently no study of FA as an estimate of individual quality for domestic goats. For this purpose, 11 landmarks were digitized in two dimensions from the crania of 24 adult goats （12 males and 12 females） belonging to the ＂White Rasquera＂ breed. The skulls showed nearly perfect bilateral symmetry. The low detected values of FA in skulls revealed a weak influence of developmental stress on this goat contemporary population and its strong ability to compensate stress.

Asymmetry in Negative Refraction of Nonlinear Waves

Recently, inwardly propagating waves （called antiwaves, AWs） in nonlinear oscillatory systems have attracted much attention. An interesting negative refraction phenomenon has been observed in a bidomain system where one medium supports forwardly propagating waves （normal waves, NWs） and the other AWs. In this paper we find that negative refraction （NR） in nonlinear media has an asymmetric property, i.e., NR can be observed only by applying wave source with proper frequency to one medium, but not the other. Moreover, NR appears always when the incident waves are dense and the refractional waves are sparse. This asymmetry is a particular feature for nonlinear NR, which can neither be observed in linear refraction processes （both positive and negative refractions） nor in nonlinear positive refraction. The mechanism underlying the asymmetry of nonlinear NR are fully understood based on the competition of nonlinear waves.

Polarization Analysis of an Asymmetrically Etched Rib Waveguide Coupler for Sensing Applications

Deeply etched rib waveguides on silicon on insulator platform were not addressed well in research publications. We have analyzed single mode condition and polarization independence of a deeply etched rib waveguide （DE-RW） structure from biosensing perspective. With this rib structure, an asymmetrically etched integrated optic directional coupler has been numerically modeled to have the same coupling length for quasi- TE and TM modes. The coupling coefficients with the glucose solution as an upper cladding were calculated using a full vector mode solver, and the bulk refractive index sensitivity of the sensor was found as 28.305 × 10^-2/RIU for a fundamental quasi-TE mode.

The Study of “Coulomb Asymmetry” in an Elliptically Polarized Laser Field

Due to the effect of Coulomb potential, the angular distribution of electron ionized in an elliptically polarized field presents an asymmetric structure, which is called "Coulomb asymmetry". In this paper, we study how to modulate the asymmetric degree of the electron angular distribution by using a semi-classical simplified tunneling model. It is found that the asymmetric structure is easily affected by three parameters: the ionization potential, the laser ellipticity,and the laser wavelength. However, the laser intensity has little effect on the asymmetric structure. To explain these phenomena we have derived an analytical formula, which clearly demonstrates the relationship between the asymmetric degree and these parameters. Moreover, we find that in elliptically polarized laser field only those electrons that are released in a certain narrow window of initial field phase are greatly effected by the Coulomb potential and play the key role in the formation of asymmetric structure. This study provides some reference values in the development of attoclock technique, which can be used to probe the tunneling process.

Meridional movement of northern and southern equatorial ionization anomaly crests in the East-Asian sector during 2002-2003SSW

The present paper investigates the asymmetrical variability of the location of the north and the south equatorial ionization anomaly(EIA) crests in the East-Asian sector,along with their association with simultaneous observations of equatorial electrojet(EEJ) strength,geomagnetic activity index,and solar flux index during the 2002-2003 sudden stratospheric wanning(SSW) event.Analysis of these observations indicates the existence of a large-scale quasi 16-day periodic meridional movement in both EIA crests,and also reveals a strong correlation between the quasi 16-day oscillation in geomagnetic latitudes of the EIA crest and EEJ strength.The latitude of the northern/southern EIA crest and the EEJ strength indicate that obvious synchronous periodic oscillations were in-phase in the northern and southern hemisphere when the SSW occurred.In addition,it is also found that both the EIA crest location and amplitude of the periodic movement of the EIA locations exhibit hemispheric asymmetry.The amplitude of the periodic movement of the EIA location in the southern hemisphere is larger than that of the northern hemisphere,and the southern EIA crest is further off from the equator than the north one.Understanding these asymmetries requires a combination of mechanisms that involve at least trans-equator meridional winds and the position of a sub-solar point;however,potential disturbances in neutral winds associated with the SSW may additionally complicate the equatorial ionospheric dynamics.