Sm原子在电离限附近的光电离谱

用两脉冲激光两步激发和光电离的方法,观察了Sm原子在电离限附近的光电离谱,测定了在45321.8～45802.9cm~(-1)能量区间的70余个能级位置.     

Calibration error analysis of electro-optical detection systems

We present detailed analysis of calibration process error for electro-optical detection systems, which can be simplified as the plane rotation around a non-orthogonal axis. By means of octonions it firstly proves that the plane rotation around a non-orthogonal axis can be decomposed into rotations around two perpendicular axes. The rotation is further divided into three steps, and the calibration error is hence discussed and obtained. The simulation and test results indicate that there are large calibration errors in calibration process. The pointing error can be effectively improved after separating error components, which provides a more accurate set data for further comDensation.     

Random walks on lattices with randomly distributed traps I. The average number of steps until trapping

For a random walk on a lattice with a random distribution of traps we derive an asymptotic expansion valid for smallq for the average number of steps until trapping, whereq is the probability that a lattice point is a trap. We study the case of perfect traps (where the walk comes to an end) and the extension obtained by letting the traps be imperfect (i.e., by giving the walker a finite probability to remain free when stepping on a trap). Several classes of random walks of varying dimensionality are considered and special care is taken to show that the expansion derived is exact up to and including the last term calculated. The numerical accuracy of the expansion is discussed.     

A micromechanical model of surface steps

The surface of an epitaxial thin film typically consists of terraces separated by steps of atomic height and it evolves largely by the motion of steps. Steps are sources of stress that interact with other residual stress fields, and these interactions have a profound effect on surface evolution. A model of the elastic field arising from a two-dimensional step is presented as a departure from the commonly used half-plane point-multipole model. The field is calculated asymptotically for small step height up to second order in terms of ‘structural’ parameters that can be determined from empirical data or atomistic calculations. Effects of a lattice mismatch and surface stress are included. The model is shown to be in remarkable agreement with atomistic predictions. It is demonstrated that second-order terms are necessary for understanding non-trivial step-step interactions, and that these second-order fields cannot be described by point sources on a half-plane.     

Controllable magnetic properties of cobalt ferrite particles derived from layered double hydroxide precursors

Cobalt ferrite CoxNi1-xFe2O4 (x=0, 0.5, 1) particles with controllable magnetic properties have been pre-pared by calcination of co-substituted NiFe2+Fe3+-layered double hydroxide (NiFe2+Fe3+-LDH) precursors prepared via a scalable method involving separate nucleation and aging steps (SNAS). Their structural and magnetic characteristics were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Measurements of magnetic properties show that the saturation magnetization (Ms) and coercivity (Hc) of the calcined products increased with increasing cobalt content. The LDH precursor-based product obtained by calcination of a mixture of CoFe2+Fe3+-LDH and NiFe2+Fe3+-LDH powders with a Co/Ni molar ratio of 1:1, exhibits a moderate value of Ms and an increased value of Hc compared to the corresponding values for an Ni0.5Co0.5Fe2O4 material prepared by calcination of a Co0.5Ni0.5Fe2+Fe3+-LDH precursor, and a physical mixture of CoFe2O4 and NiFe2O4 with a Co/Ni molar ratio of 1 : 1. These results may provide a way to regulate magnetic anisotrupy of ferrite spinels by varying the composition of the LDH precursors.     

High-temperature X-ray diffraction study of thermolysis of the double complex salt [Rh(NH3)5Cl][PtCl4]

The formation process of a nanosize powder of the equilibrium solid solution Pt_0.50Rh_0.50 by thermolysis of the double complex salt [Rh(NH₃)₅Cl][PtCl₄] under hydrogen or helium and in vacuo was studied in situ by X-ray diffraction and synchrotron radiation. The reduction temperature of the metals in the cationic and anionic moieties of the starting complex is the main factor responsible for the mechanism of solid solution formation. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1069–1073, July, 2006.     

The two steps thermal decomposition of titanium hydride and two steps foaming of Al alloy

1 Introduction Al alloy foam with closed pores prepared by melt foaming, realizing the lightness, high specific strength and multifunction of structure material, is becoming one of the hotspots[1―11]. In order to meet the demand of high-tech, preparing s…     

Rate constants of elementary steps of the reversible chain reaction of N-phenyl-1,4-benzoquinonemonoimine with 2,5-dichlorohydroquinone

The kinetics of reversible chain reactions in quinoneimine-hydroquinone systems has first been studied for the reaction of N-phenyl-1,4-benzoquinonemonoimine with 2,5-dichloro-hydroquinone used as an example. The dependences of the reaction rate on the concentration of the initial reactants, initiator, and each product were studied. The reliable estimates of the rate constants of 11 (of 12) elementary steps of this reaction were obtained from the experimental data using the earlier derived formulas and the method of equal concentrations developed in the present work. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 849–855, May, 2007.     

一种新的快速逼近真值的程序算法──分布误差法

本文介绍一种新的逼近真值的快速程序算法及其应用。     

The Modified Upwind Finite Difference Fractional Steps Method for Compressible Two-phase Displacement Problem

For compressible two-phase displacement problem,the modified upwind finite difference fractionalsteps schemes are put forward.Some techniques,such as calculus of variations,commutative law of multiplicationof difference operators,decomposition of high order difference operators,the theory of prior estimates and tech-niques are used.Optimal order estimates in L~2 norm are derived for the error in the approximate solution.Thismethod has already been applied to the numerical simulation of seawater intrusion and migration-accumulationof oil resources.