环流问题与双小孔型脉冲管制冷机研究

１前言脉冲管制冷机已基本达到了实用化的程度。但在理论方面,仍有较多问题存在,其中双向进气型脉冲管制冷机内的环流问题成为一个讨论的热点和难点。１９９１年朱绍伟进行双向进气方案的实验验证时［１］,已经提到了环流问题,即进出双向阀门的流量不等造成的冷端温度...     

Stopping power of an electron gas: The sum rule approach

The stopping power of dense electron plasmas is determined using a simplified version of the method of moments based on some interpolation formulas for the sum rules of the loss function. The energy losses of ions are evaluated with various projectile charges moving in a plasma at different values of the coupling and degeneracy parameters. The losses of slowly moving charged particles are closely examined. The results obtained are compared with those of some alternative approaches and the particle‐in‐cell (PIC) simulation data.     

关于离散形式结点域定理证明的几点注记

本文指出了文[1]的主要定理(定理4与定理6)证明中的错误,并对其进行了修正,给出了正确的证明.     

Small fractional parts of additive forms

Letf(x)=θ₁ x ₁ ^k +...+θ _s x _s ^k be an additive form with real coefficients, and ∥α∥ = min {|α-u|:uεℤ} denote the distance fromα to the nearest integer. We show that ifθ ₁,…,θ _s , are algebraic ands = 4k then there are integersx ₁,…,x _s , satisfying l ≤x ₁,≤ N and ∥f(x)∥ ≤ N ^E , withE = − 1 + 2/e. Whens = λk, 1 ≤λ ≤ 2k, the exponentE may be replaced byλE/4, and if we drop the condition thatθ ₁,…,θ _s , be algebraic then the result holds for almost all values of θεℝ ^s . Whenk ≥ 6 is small a better exponent is obtained using Heath-Brown’s version of Weyl’s estimate.     

RELATIONS BETWEEN SOLUTIONS TO STOCHASTIC DIFFERENTIAL EQUATIONS DRIVEN BY SEMIMARTINGALE WITH NON-LIPSCHITZ COEFFICIENTS

In this paper, a class of stochastic differential equations (SDEs) driven by semi-martingale with non-Lipschitz coefficients is studied. We investigate the dependence of solutions to SDEs on the initial value. To obtain a continuous version, we impose the conditions on the local characteristic of semimartingale. In this case, it gives rise to a flow of homeomorphisms if the local characteristic is compactly supported.     

General Formalism for Setting Up Unitary Transform Operators from Classical Transforms via IWOP Technique

We present a general formalism for setting up unitary transform operators from classical transforms via the technique of integration within an ordered product of operators, their normally ordered form can be obtained too.     

DS-OCDMA系统中FBG编解码器的研究

详细阐述了平行结构和串联结构光纤布喇格光栅编解码器的设计思想,探讨了它们在直接序列扩频光纤码分多址系统中的应用,并推导了各自的编解码原理.通过分析相应系统在功率效率和误码率等方面的性能,得出了最佳的设计参量.结果表明,该编解码器除具有与同一结构类型的光纤延迟线编解码器相似的性能外,还具有相位编解码能力.