Applied Physics A 51, no. 2 (1990)

Applied Physics A 51, no. 2 (1990)     

On the Solution of Some Diffusion Equations with Concentration-dependent Diffusion Coefficients--II

On the basis of further analytical results an improved algorithmfor the numerical solution of a non-linear differential systemarising from some diffusion systems with concentration-dependentdiffusion coefficients is presented. In comparison with thepreviously reported approach the present method does not requirethe solution of an approximate equation and is simpler and moreeffective in its iteration processes. An example of numericalsolutions of a diffusion system from the investigation of protonsdiffusion is demonstrated.     

K+介子衰变的分枝比

The branching ratio of the following three modes of K⁺-meaon decay K⁺→μ⁺+π⁰+ν K⁺→e⁺+π⁰+ν K⁺→μ⁺+ν is calculated by using the theory of the universal Fermi weak interaction proposed by Feymann and others. Perturbation method with cut-off is used. The ratio obtained is 1:1.5:12, which is in fair agreement with the experimental value 1:1:15. It is shown, other conbinations of Fermi interactions can not give result in agreement with experiment.     

Amplification Characteristics of Optical Fibres Doped with Nano Materials of InP

We take an enhanced structure of existing optical fibres to investigate the amplification characteristics. Nano and optical fibre technologies both are employed in our structure, i.e. the so-called nano-film amplification fibre where nano-film is inserted between the core and the inner cladding of the optical fibre. In the developed model, InP is chosen as a doped semiconductor to examine its amplification performance and 69.7nm is chosen as the thickness of the film. From our experimental results, the optical fibre structure shows its significant amplification characteristics for wavelength between 1080nm and 1491 nm. Amplification characteristics are also found in wavelengths 906-1044 nm and 1524-1596nm.     

Isoscaling Parameter α as a Possible Probe of Medium Effect of Nucleon--Nucleon Cross Section

The medium effect of nucleon-nucleon cross section reed σ^medNN （αm） on the isoscaling parameter α is investigated for two central nuclear reactions ^40 Ca＋ ^40Ca, ^60Ca＋^60Ca within isospin-dependent quantum molecular dynamics at beam energies from 40 to 50 MeV/nucleon. It is found that there is the very obvious medium effects of nucleonreed nucleon cross section σ^medNN （αm） on the isoscaling parameters a. In this case the isoscaling parameter a is a possible probe of the medium effect of nucleon-nucleon cross section σ^medNN （αm） in the heavy ion collisions. The mechanism of the above-mentioned properties is studied and discussed.     

△-Resonance Effective Mass in Medium

Based on the relativistic chiral effective field theory, we study the effective mass of the △-resonance in medium by investigating the self-energy of the △-resonance related to the πN decay channel in symmetric nuclear matter. We find that the effective mass of △-resonance decreases evidently with increasing nuclear density p. In our calculation, we also consider the influence of the shifts of the nucleon mass, pion mass and its decay constant due to the restoration of chiral symmetry in medium. The results are roughly consistent with the data given by Lawrence Berkeley National Laboratory.     

ACTIVE IMPACT CONTROL SYSTEM DESIGN WITH A HYDRAULIC DAMPER

We propose a new active impact control (or absorber) system that is able to respond to a highly rapid impact and a large flow rate. The system has advantage over a passive system regarding a feasible pressure and displacement regulation. The impact control system constructs both internal and external dampers, that is its orifice is placed inside and outside the hydraulic cylinder. The designed system has a set of logic valves, which respond rapidly to an external impact and are capable of discharging an instant excessive hydraulic flow, and a servo valve to control the pilot chamber of the logic valve. The impact control system is designed and fabricated based on an appropriate mathematical modelling and its dynamic analysis, and on various control performances. The control performance is verified by simulations and experiments.     

A NEW METHOD FOR IN-PLANE VIBRATION ANALYSIS OF CIRCULAR RINGS WITH WIDELY DISTRIBUTED DEVIATION

A new analytical method was developed to predict the in-plane mode shapes and the natural frequencies of a ring with widely distributed deviation. The Laplace transform was used to find the exact solution of eigenvalue problem without assuming any trial functions and finite elements. The widely distributed deviation was effectively formulated in the theory using Gauss-Legendre quadrature. The validity of the proposed method was examined through finite element analysis and modal test. The effects of partial change of the density, the stiffness, and the thickness on the natural frequencies of the ring were investigated.     

NON-LINEAR AEROELASTIC ANALYSIS USING THE POINT TRANSFORMATION METHOD, PART 1: FREEPLAY MODEL

A point transformation technique is developed to investigate the non-linear behavior of a two-dimensional aeroelastic system with freeplay models. Two formulations of the point transformation method are presented, which can be applied to accurately predict the frequency and amplitude of limit cycle oscillations. Moreover, it is demonstrated that the developed formulations are capable of detecting complex aeroelastic responses such as periodic motions with harmonics, period doubling, chaotic motions and the coexistence of stable limit cycles. Applications of the point transformation method to several test examples are presented. It is concluded that the formulations developed in this paper are efficient and effective.     

含"单"及"双"吡唑啉基化合物的光致发光和电致发光的比较研究

对7种含"单"或"双"吡唑啉化合物在溶液和在固体器件[ITO/TPD/TPBI-2%EP/TPBI/Mg-Ag]中作为掺杂发光材料的电致发光特性进行了研究.结果表明,由吡唑啉化合物所构成的器件具有优良的电致发光特性.特别是在5-位处联有芳基的双吡唑啉化合物,由于它们具有良好的成膜能力和较高的玻璃化转变温度,因此所制得的器件有很好的稳定性.结果还表明,含双吡唑啉基化合物的荧光量子产率较含单吡唑啉基者为低.由它们所构成器件的电致发光能力也大体反映出相同的趋势.