The influence of molecular structure of protein on the acoustic nonlinearity parameter B/A

I.IntroductionAcousticnonlinearityparameterB/Adescrjbesthenonlilleareffectsofasoundwavetrav-ellingthroughamedium.Withtheapplicationofhighmowerultrasonicwavetomedicine,thenonlineareffectsbecomemoreandmoreimportant.EspeciallybecauseB/Aissensitivetothepathologicalstateofbiologicaltissues[1-2])thisprovidesprospectiveapplicationinmedicaldiagnosis.Atpresent,thestudyinthisareaemphasizesontwoaspects.OneistodevelopnewmedicalimagingtechniquesbyusingthisnonlinearityparameterB/Al1'3-'];theotheristostu…     

溶胶—凝胶法制备CdS微晶掺杂TiO2／SiO2薄膜及其非线性光学特性

采用溶胶－凝胶方法在普通的载玻片上制备了ＣｄＳ微晶掺杂的ＴｉＯ２／ＳｉＯ２复合薄膜。用正硅酸乙酯、钛酸丁酯、醋酸镉作原料，比较了两种硫化剂：硫尿和硫代乙酰氨的硫化作用。Ｘ射线衍射谱和拉曼光谱揭示了ＣｄＳ微晶镶嵌在ＴｉＯ２／ＳｉＯ２薄膜的玻璃网络中。不同热处理温度、不同热处理时间的吸收光谱表明薄膜中存在着量子尺寸效应。采用Ｚ扫描技术测量了薄膜的非线性吸收及非线性折射率ｎ２＝－４．６７×１０－７ｅｓｕ。     

Propagation Dynamics of Ultrashort Optical Pulses in Nonlinear Coupled-Cavity-Type Multilayered Structures: a Numerical Study

A numerical study of the propagation dynamics of ultrashort pulses in a coupled-cavity-type multilayered structure doped with Kerr-type nonlinearity showed that such a structure improves the switching contrast of recently proposed optical-limiting and switching devices consisting of a nonlinear Bragg reflector.     

对力学非线性和磁场非线性综合作用下扬声器低频跳变的探讨

力学非线性和磁场非线性是扬声器非线性现象的两个因素。本文分析了仅力学非线性的扬声器低频振动方程的临界跳变条件，采用等效线性化法讨论了磁场非线性对扬声器跳变的影响。证实了抑制扬声器跳变的有效途径是增大电磁耦合因子B1。     

Asymptotic behavior of solutions to Schrödinger equations with a subcritical dissipative nonlinearity

We study the asymptotic behavior in time of solutions to the initial value problem of the nonlinear Schrödinger equation with a subcritical dissipative nonlinearity λ|u|^p−1u, where 1<p<1+2/n, n is the space dimension and λ is a complex constant satisfying Imλ<0. We show the time decay estimates and the large-time asymptotics of the solution, when the space dimension n?3, p is sufficiently close to 1+2/n and the initial data is sufficiently small.     

Adaptive Feedback Linearization for the Control of a Typical Wing Section with Structural Nonlinearity

Earlier results by the authors showed constructions of Lie algebraic, partial feedback linearizing control methods for pitch and plunge primary control utilizing a single trailing edge actuator. In addition, a globally stable nonlinear adaptive control method was derived for a structurally nonlinear wing section with both a leading and trailing edge actuator. However, the global stability result described in a previous paper by the authors, while highly desirable, relied on the fact that the leading and trailing edge actuators rendered the system exactly feedback linearizable via Lie algebraic methods. In this paper, the authors derive an adaptive, nonlinear feedback control methodology for a structurally nonlinear typical wing section. The technique is advantageous in that the adaptive control is derived utilizing an explicit parameterization of the structural nonlinearity and a partial feedback linearizing control that is parametrically dependent is defined via Lie algebraic methods. The closed loop stability of the system is guaranteed to be stable via application of La Salle's invariance principle.     

Interesting effect of optical Kerr nonlinearity in expanding single-mode regime of optical fibers using dispersion-flattened profiles

An interesting effect of optical Kerr nonlinearity is reported from theoretical investigation on the fundamental and first higher mode cutoff frequencies in single-mode fibers doped with highly nonlinear materials like CdS_xSe_1−x with W-type dispersion-flattened profiles. It is observed that whereas the single-mode regime decreases absolutely for dispersion-shifted profiles due to reduction of the first higher order mode cutoff frequency as is evident from earlier studies, it increases for W-type profiles for such nonlinearity taking its effect on the nonzero fundamental mode cutoff frequency into consideration. Thus, one can go further down below the fundamental mode cutoff frequency while using W-fibers in single mode nonlinear fiber devices involving evanescent field coupling in the low V region.     

新型含有砜基吲哚发色团侧基的聚硅氧烷的合成与非线性光学性能研究

采用后功能化的方法合成了两种含有砜基吲哚二阶非线性光学发色团侧基的聚硅氧烷分子，通过核磁、红外、紫外-可见、示差扫描量热分析等手段对所得的聚合物进行了表征．此合成方法简便易行，易于产物的分离提纯，为二阶非线性光学材料的合成提供了一种新方法．通过二次谐波产生(SHG)方法测得该聚合物的二阶非线性光学系数d33值分别为21和17pm／V．     

SPHERICAL NONLINEAR PULSES FOR THE SOLUTIONS OF NONLINEAR WAVE EQUATIONS Ⅱ, NONLINEAR CAUSTIC

This article discusses spherical pulse like solutions of the system of semilinear wave equations with the pulses focusing at a point and emerging outgoing in three space variables. In small initial data case, it shows that the nonlinearities have a strong effect at the focal point. Scattering operator is introduced to describe the caustic crossing. With the aid of the L∞norms, it analyzes the relative errors in approximate solutions.     

Optical solitons supported by finite waveguide lattices with diffusive nonlocal nonlinearity

We investigate the properties of fundamental, multi-peak, and multi-peaked twisted solitons in three types of finite waveguide lattices imprinted in photorefractive media with asymmetrical diffusion nonlinearity. Two opposite soliton self-bending signals are considered for different families of solitons. Power thresholdless fundamental and multi-peaked solitons are stable in the low power region. The existence domain of two-peaked twisted solitons can be changed by the soliton self-bending signals. When solitons tend to self-bend toward the waveguide lattice, stable two-peaked twisted solitons can be found in a larger region in the middle of their existence region. Three-peaked twisted solitons are stable in the lower (upper) cutoff region for a shallow (deep) lattice depth. Our results provide an effective guidance for revealing the soliton characteristics supported by a finite waveguide lattice with diffusive nonlocal nonlinearity.