Solitonic Information Transmission in General Relativity

An exact solution of the vacuum Einstein＇s field equations is presented, in which there exists a congruence of null geodesics whose shear behaves like a travelling wave of the KdV equation. On the basis of this exact solution, the feasibility of solitonic information transmission by exploiting the nonlinearity intrinsic to the Einstein field equations is discussed.     

Correspondence Between Oscillations and Emitted Photon Closed-Orbits in Spontaneous Emission Rate of an Atom Near a Dielectric Slab

We study the oscillations in the spontaneous emission rate of an atom near a dielectric slab. The emission rate is calculated as a function of system size using quantum electrodynamics. It exhibits multi-periodic oscillations. Four frequencies of the oscillations are extracted by Fourier transforms. They agree with actions of photon closed-orbits going away and returning to the atom. These oscillations are explained as manifestations of quantum interference effects between the emitted photon wave near the atom and the returning photon waves travelling along various closed-orbits.     

Suppression of Phase and Amplitude Damping Decoherence in a Three-Level Atom in A-Configuration Using Bang-Bang Controls

In this paper, we present decoupling bang-bang operations for the suppression of general decoherence, both amplitude and phase damping, in a three-level system in A-configuration. We give a program to design a sequence of periodic twinborn pulses to suppress the decoherence in such the system.     

Al/AlN多层膜的摩擦磨损性能研究

采用柱状靶磁控溅射系统制备Al/AlN纳米多层膜,采用纳米压痕仪测量Al/AlN纳米多层膜的纳米硬度,在UMT-2M型摩擦磨损试验机上评价其摩擦磨损性能.结果表明:当AlN层较厚时,薄膜在很短时间内被磨穿;调节Al/AlN层厚比为2.9/1.1时,薄膜的摩擦磨损性能明显提高;当保持Al/AlN层厚比为2.9/1.1、变化多层膜的调制周期时,薄膜的摩擦系数较低,但硬度较低的薄膜由于承载能力不够,不能够保持优良的摩擦磨损性能.     

含纳米添加剂的润滑体系在摩擦过程中的接触电阻研究

采用UMT-2型微摩擦磨损试验机考察了4种纳米颗粒LaF3、Ag、SiO2 及Al2O3作为润滑油添加剂在摩擦过程中的接触电阻随时间变化的情况,并由此监测摩擦副表面的成膜状况;采用X射线光电子能谱仪分析4种纳米添加剂润滑下磨损表面典型元素的化学状态,并结合接触电阻测试结果分析纳米油润滑添加剂的润滑机理.结果表明:接触电阻测试能够适时监测添加剂在摩擦副表面的成膜过程,4种纳米润滑油添加剂在边界润滑条件下均能够在磨损表面沉积成膜,其在试验过程中的化学状态没有发生变化,但4种纳米润滑油添加剂在摩擦过程中的成膜性能不同,Ag和LaF3在摩擦过程中的沉积速率、沉积膜厚度及其在摩擦副表面的结合强度优于SiO2和Al2O3.     

关于BCI逻辑的一种偏序代数

通常,人们认为Kiyoshi Iséki在20世纪60年代引入的BCI-代数是组合逻辑中BCI逻辑的代数对等物。然而这种广为人知的断言却是有问题的,因为BCI逻辑关于BCI代数是不完备的。在本文中,我们引入一种称为MPE的偏序代数。在MPE中的每个不等式对应BCI逻辑中的一个重言式且反之亦然,从而MPE代数是与BCI逻辑完备的代数类。     

基于方向信息测度的最小模糊度准则边缘检测

将像素点的方向信息测度作为判别边缘点的特性指标,借用Huang等构造的自适应确定分割阈值的思想,本文提出了一种基于方向信息测度的最小模糊度准则边缘检测方法。文中提出的方法,一方面由于采用了方向信息测度,可以很好地将边缘点和非边缘点区分开来;另一方面通过最小化模糊度,自适应地将给定图像的所有像素点按照方向信息测度分成两类,从而达到提取边缘的目的。实验结果证明,我们提出的方法能够很好地判别边缘点,有效地提取图像的边缘。     

信息时代的铌酸锂晶体:进展与展望

铌酸锂晶体具有非线性效应、电光效应、声光效应、光折变效应、压电效应与热释电效应等多种物理特性,在表面声波器件、光电器件、声光器件等方面获得广泛的应用.经历了六十多年的发展,铌酸锂晶体历久弥新,随着材料特性的不断开发,新功能、新器件、新应用层出不穷,尤其是铌酸锂单晶薄膜在薄膜滤波器、集成光电器件等领域的性能具有明显优势,...     

Weak Graph Map Homotopy and Its Applications∗

The authors introduce a notion of a weak graph map homotopy (they call it M-homotopy), discuss its properties and applications. They prove that the weak graph map homotopy equivalence between graphs coincides with the graph homotopy equivalence defined by Yau et al in 2001. The difference between them is that the weak graph map homotopy transformation is defined in terms of maps, while the graph homotopy transformation is defined by means of combinatorial operations. They discuss its advantages over the graph homotopy transformation. As its applications, they investigate the mapping class group of a graph and the 1-order MP-homotopy group of a pointed simple graph. Moreover, they show that the 1-order MP-homotopy group of a pointed simple graph is invariant up to the weak graph map homotopy equivalence.     

桑蚕种良卵率调查中样本间卵粒数的偏差控制方法

桑蚕种良卵率是蚕种质量检验的重要指标,控制样本间卵粒数的偏差是保证良卵率准确性的关键。通过对桑蚕卵粒重的调查分析,得出其分布服从正态分布。若从一批蚕种中抽取1g卵作为样本,则来自同一总体的2个样本的卵粒数之差不超过16粒,其置信概率为95%;当置信概率取99%时,两个样本的卵粒数之差不超过21粒。文章为蚕业生产提供了一种实用的克卵粒数偏差控制方法。