Dynamics of arrays of legs powered by a discrete electrical model of nerve

This paper studies the dynamics of an array of legs connected through magnetic coupling at nodes of a discrete electrical model of nerve fibre or a linear electric line. Considering legs fixed on spring, it is found that they exhibit pulse like behavior when the electrical signal propagates in the array. The amplitude of the pulse like motion increases with the magnitude of magnetic field. Legs without spring undergo a step motion at the passage of the electrical signal, advancing in a given distance before they stop. The magnitude of the step also increases with the magnetic coupling. Considering a linear electrical line excited at a single node, it is found that the legs oscillate with decreasing amplitude till the center of the line and increasing amplitude from the center to the first node of the linear line.     

Generalized thermo-visco-elastic problem of a spherical shell with three-phase-lag effect

This problem deals with the thermo-visco-elastic interaction due to step input of temperature on the stress free boundaries of a homogeneous visco-elastic isotropic spherical shell in the context of generalized theories of thermo-elasticity. Using the Laplace transformation the fundamental equations have been expressed in the form of vector–matrix differential equation which is then solved by eigen value approach. The inverse of the transformed solution is carried out by applying a method of Bellman et al. [R. Bellman, R.E. Kolaba, J.A. Lockette, Numerical Inversion of the Laplace Transform, American Elsevier Publishing Company, New York, 1966]. The stresses are computed numerically and presented graphically in a number of figures for copper material. A comparison of the results for different theories (TEWED (GN-III), three-phase-lag method) is presented. When the body is elastic and the outer radius of the shell tends to infinity, the corresponding results agree with the result of existing literature.     

A Model of Subdiffusive Interface Dynamics with a Local Conservation of Minimum Height

We define a new model of interface roughening in one dimension which has the property that the minimum of interface height is conserved locally during the evolution. This model corresponds to the limit q of the q-color dimer deposition-evaporation model introduced by us earlier [Hari Menon and Dhar, J. Phys. A: Math. Gen. 28:6517 (1995)]. We present numerical evidence from Monte Carlo simulations and the exact diagonalization of the evolution operator on finite rings that growth of correlations in this model is subdiffusive with dynamical exponent z2.5. For periodic boundary conditions, the variation of the gap in the relaxation spectrum with system size appears to involve a logarithmic correction term. Some generalizations of the model are briefly discussed.     

Room-Temperature Near-Infrared Metastable Species Measured by Phase-Sensitive Lock-in and Fourier Transform Techniques

An ultrasensitive detecting system coupled with either a lock-in or Fourier transform technique has been used to detect near-infrared (1000-2500 nm) metastable species in room temperature solutions. These species include O₂(¹Δ_g), O₂(¹σ⁺_g), the solvent induced satellite peak of molecular singlet oxygen (¹Δ_g) emission, and the triplet state of bis(triisobutylsiloxy)silicon-2,-3-naphthalocyanine (SilNC). Using the O₂(¹Δ_g) emission in benzene as a standard, the quantum yield and radiative decay rate of SiINC triplet state have been determined. Depending on types of spectral acquisition, special techniques such as phase-distinguishing and step scan capabilities were utilized. Their advantages and disadvantages are discussed.     

光栅单色仪最佳分度的判断

本文利用波动光学的简单方法讨论光栅单色仪的分辨极限与步进电机参数的联系,为最佳利用分辨极限提供了简单可行的实验方法,也给出了用步栅单色仪的分辨率可供参考的例证。     

高功率激光装置中超快电脉冲发生器的研究

报导了一种基于雪崩晶体管和阶跃恢复二极管的超快前沿、低触发晃动方波电脉冲产生技术.利用雪崩晶体管的电触发雪崩导通特性得到脉冲主体,再用阶跃恢复二极管的超快阶跃恢复特性对脉冲前沿整形,从而得到输出脉冲幅度23 V、输出阻抗50Ω、脉冲前沿小于160 ps的方波脉冲,脉冲触发晃动小于4.5 ps(rms),脉冲宽度5 ns,幅度稳定性优于3%,顶部不平坦度优于5%.该脉冲发生器在“神光Ⅲ”高功率激光原型装置前端系统中获得成功应用.     

刺状Pd纳米粒子的室温合成及其对乙醇氧化的电催化性能

室温下以氯化胆碱为稳定剂,用化学还原法合成了刺状Pd纳米粒子(Pdtnh0o0r0n).透射电子显微镜和电化学循环伏安研究结果表明Pdtnh0o0r0n具有较高密度的台阶位,与商业Pd黑催化剂相比较,Pdtnh0o0r0n对乙醇氧化的电催化活性显著提高,氧化电流密度是商业Pd黑催化剂的1.2倍(-0.40--0.30V)-1.5倍(-0.65--0.40V),起始氧化电位和峰电位均负移50mV.相同电流密度下,Pdtnh0o0r0n催化剂对乙醇的氧化电位均更低.     

Search for adsorption potential energy minima of NO on Pt(9 9 7) at 11 K

We observed four kinds of adsorbed NO molecules on Pt(9 9 7) at 11 K using infrared reflection absorption spectroscopy (IRAS). The peaks at 1690, 1484 and 1615 cm⁻¹ are assigned to the N-O stretching modes of the on-top site and the hollow site on the terrace and the bridge site at the step, respectively. The 1385 cm⁻¹ peak is observed below ∼70 K. We assign the 1385 cm⁻¹ peak to the hollow site of the (1 1 1) microfacet at the step or the lower-terrace hollow site nearest to the step. By heating, site-to-site hopping to the more stable site occurs and the relative stability of four adsorption sites can be determined.     

Scaling,propagation, and kinetic roughening of flame fronts in random media

We introduce a model of two coupled reaction-diffusion equations to describe the dynamics and propagation of flame fronts in random media. The model incorporates heat diffusion, its dissipation, and its production through coupling to the background reactant density. We first show analytically and numerically that there is a finite critical value of the background density below which the front associated with the temperature field stops propagating. The critical exponents associated with this transition are shown to be consistent with meanfield theory of percolation. Second, we study the kinetic roughening associated with a moving planar flame front above the critical density. By numerically calculating the time-dependent width and equal-time height correlation function of the front, we demonstrate that the roughening process belongs to the universality class of the Kardar-Parisi-Zhang interface equation. Finally, we show how this interface equation can be analytically derived from our model in the limit of almost uniform background density.     

多晶薄膜表面粗化与生长方式转变

采用原子力显微镜研究了磁控溅射多晶薄膜表面粗化行为对归一化沉积温度T_s/T_m(T_s是沉积温度，T_m是材料熔点)的依赖性与薄膜生长方式转变行为.随着T_s/T_m增加，薄膜表面粗糙度增加，而表征粗糙度随时间演化特征的生长指数β历经了先减小再增加的过程.β对T_s/T_m的依赖关系反映了薄膜生长方式的转变行为，即薄膜生长依次由随机生长方式向表面扩散驱动生长方式与异常标度行为生长方式转变.在低于体扩散控制薄膜生长的温度时，晶界扩散机理导致多晶薄膜的表面粗化的异常标度行为. 关键词： 多晶薄膜 表面粗化 温度 生长