衍射光学元件衍射效率影响混合光学系统性能的一种分析方法

本文从衍射光学元件的衍射效率入手,详细地分析了衍射光学元件衍射效率同混合光学系统光学传递函数的关系,并通过一个实际例子对所分析的结果进行了深入讨论.     

Spin dependent fragmentation functions for heavy flavor baryons and single heavy hyperon polarization

Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are carculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. Λ _b , Λ_c and Ξ _c production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted Λ_c polarization is roughly in agreement with experiment.     

Reliability analysis of stochastic structural system considering static strength, stiffness and fatigue

Multi-failures are possible to appear in the process of using the structural system, such as dead load failure, fatigue failure and stiffness failure. The expression of residual resistance is given based on the impact of random crack propagation in- duced by the fatigue load on the critical limit stress and section modulus in this paper. The failure modes of every element of the structural system are analyzed under dead and fatigue loads, and the influence of the correlation of failure modes on reliability of the element is considered. Failure mechanism and the correlation of failure modes under dead and fatigue loads are discussed, and the method of reli- ability analysis considering static strength, fatigue and stiffness is given. A nu- merical example is analyzed, which indicates that the failure probability is different for different use life and the influence of dead and fatigue loads on reliability of the structural system is different as well. This method of reliability analysis, in the pa- per, is better than the method only considering a single factor (or static strength, or fatigue, or stiffness, etc.) in the case of practical engineering.     

Structural properties of silver iodide and copper iodide

The structural changes within the Silver iodide (AgI) and Copper iodide (CuI) induced by pressure have been investigated using an effective interaction potential. CuI and AgI in their parent zinc blende (ZnS) to rock salt (NaCl) through an intermediate structure have been reported. The calculated values for the phase transition pressures and associate volume collapses are generally in good agreement with measured data.      

Control of spontaneous emission in a five-level system

We study the control of spontaneous emission in a five-level atomic system driven by four fields. We show that with the variation of dynamical variables, namely, Rabi frequencies and carrier phases of driven fields, a wide variety of the spectral behavior can be obtained, including extreme spectral narrowing. Our system can be found easily in real atoms.     

Analysis of an FRW cosmological model

The Einstein field equations for the Friedmann universe reduce to a system of three first-order equations for the space-like components and a constraint from the temporal component. We analyse the system from the viewpoints of symmetry and singularity analyses. The solutions of particular relevance to Cosmology are highlighted.      

Linear polarization Yb<Superscript>3+</Superscript>-doped fiber laser with novel innerclad structures

Results on high radiance Yb³⁺-doped fiber lasers with novel double innerclad structures (double-D clad and four hole) and polarized output at ≈1090 nm are presented. We have demonstrated >40% of the total output power being polarized, making the fiber laser suitable for LIDAR and second-harmonic generation (SHG) applications. It also showed a 10-nm tuning range with low (less than 10 mW) average power variations. The narrow linewidth source was pumped with a low cost, low brightness laser diode, and exhibited a relatively low slope efficiency, which gives room for improvement by using a 976-nm pump source where Yb³⁺ has a narrower linewidth and at least five times higher absorption.     

Double-Alekseev inverse scattering method in the stationary axi-symmetric vacuum gravitation field equations

We present a new improvement to the Alekseev inverse scattering method. This improved inverse scattering method is extended to a double form, followed by the generation of some new solutions of the double-complex Kinnersley equations. As the double-complex function method contains the Kramer-Neugebauer substitution and analytic continuation, a pair of real gravitation soliton solutions of the Einstein’s field equations can be obtained from a double N-soliton solution. In the case of the flat Minkowski space background solution, the general formulas of the new solutions are presented.      

First-Passage and Extreme-Value Statistics of a Particle Subject to a Constant Force Plus a Random Force

We consider a particle which moves on the x axis and is subject to a constant force, such as gravity, plus a random force in the form of Gaussian white noise. We analyze the statistics of first arrival at point x ₁ of a particle which starts at x ₀ with velocity v ₀. The probability that the particle has not yet arrived at x ₁ after a time t, the mean time of first arrival, and the velocity distribution at first arrival are all considered. We also study the statistics of the first return of the particle to its starting point. Finally, we point out that the extreme-value statistics of the particle and the first-passage statistics are closely related, and we derive the distribution of the maximum displacement m=max  _t [x(t)].