多孔硅发光峰温度行为的研究

实验研究了多孔硅（Ｐｏｒｏｕｓ Ｓｉｌｉｃｏｎ）光致发光峰随测量温度的变化,发现发光峰位随温度的移动与发光峰的能量有关。随温度升高,发光峰波长较长的样品它们的发光峰都移向高能,面发光峰能量较高的样品它们的发光峰都移向低能,发光峰波长位于７４０ｎｍ附近的样品,它们的发光峰与测量温度无关。对上术结果的起源作了讨论。     

Storage of ultracold neutrons in vessels whose walls are made from graphite,fluorine polymer oil,or heavy-water ice

The possibility of attaining the calculated probabilities of the losses of ultracold neutrons (UCN) stored in vessels whose walls are made from graphite, fluorine polymer oil, or heavy-water ice is tested experimentally. It is found that UCN hitting the walls of a graphite vessel undergo additional inelastic scattering not predicted by the theory. It is shown that this scattering may be due to the presence of surface hydrogen that provides a channel of UCN leakage slightly varying with temperature. For vessels whose walls are coated with fluorine polymer oil, additional inelastic UCN scattering is also observed and is found to be efficiently suppressed with decreasing temperature. The experimentally observed and calculated values of the probabilities of UCN losses are shown to be in good agreement for vessels whose walls are made from heavy-water ice.     

Quantum mechanical measurement of non-orthogonal states and a test of non-locality

We propose a model of measurement of a non-hermitan observable whose states are described by non-orthogonal vectors. This model is used to analyse a proposal for testing non-locality in quantum mechanics using a system whose physically observable states are not mutually orthogonal.     

Singular filaments organize chemical waves in three dimensions: III. Knotted waves

This is the third of a series of papers on the anatomy of three-dimensional organizing centers in excitable media. We here ask whether all self-consistent waves in excitable media are topologically equivalent to the experimentally-verified scroll ring, whose axis lies in a plane. As a test case we examine a scroll ring whose axis contains a knot. It proves to be incompatible with the requirements of physical chemistry unless simultaneously twisted by an amount equal to the “writhing number” of its axis (which is zero for planar closed curves). Appropriate initial conditions are suggested for experimentally creating a wave whose source is a scroll ring knotted and twisted in this way.     

非设计工况下低比速泵叶轮内不稳定流动和湍流度试验

采用两维激光流速仪，在非设计工况下对三种泵叶轮不稳定流动和湍流度进行了测试，结果表明：叶轮内不稳定流动和湍流度受旋转和曲率及入流状态的综合影响，呈十分复杂的空间分布，偏离设计点时湍流强度和流动脉动与叶轮内流场相互关联，相对于设计工况都更要高些。     

Plasma resonance of granular indium films deposited on rough surfaces of NaCl and KCl single crystals

Granular films whose bands of plasma resonance are anisotropic are obtained by vacuum deposition of indium on rough surfaces of NaCl and KCl single crystals. On electron-microscopic pictures of samples, sections whose granules form chains with distances between them somewhat larger than the distances between the ganules in the chains are found. The maximum of the absorption band in polarized light along the chains is shifted into the low-frequency region of the spectrum in comparison to the abosorption band’s maximum in polarized light perpendicular to the chains. A second band of plasma resonance whose frequency is equal to the free-running frequency of electrons in a granule is found in the high-frequency region of the spectrum. Kharkov State University, 4, Svoboda Ave., 310077, Kharkov, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 5, pp. 799–803, September–October, 1998.     

The Most General Set of Lagrange Functions Yielding Galilei Covariant Equations of Motion Having the Same Set of Solutions

The nonrelativistic case of two point particles in the (1 + 1)-dimensional space is considered. The existence of an autonomous Lagrange function is assumed, whose Euler-Lagrange Equations are forminvariant under the Galilei group. We show how to find all autonomous Lagrange functions, giving rise to Euler-Lagrange Eqzations, which again are Galilei covariant and whose set of solutions coincides with the set of solutions of the original equations, we started with. We are going to construct explicitly the most general expressions for the Lagrange functions as well as for the Equations of Motion. We supplement our considerations by some simple examples. We give also a short account on an extension of our formalism to the case of Equations of Motion, which are no longer Galilei covariant but whose solutions belong still to the same set as the previous one.     

Fluctuation,relaxation, and extensivity of macrovariables in nonequilibrium systems

The extensive property of a macrovariable is proved for a quantal system whose Hamiltonian depends on time and for a stochastic system whose temporal evolution operator depends on time. These generalized situations are concerned with bulk-contact open systems. The extensive property, fluctuation, and nonlinear relaxation are investigated explicitly by calculating rigorously generating functions in exactly soluble models such as the linear stochastic model and linearXY model. The relation between the nonlinear critical slowing down and linear critical slowing down is also discussed.     

自旋相关的电子隧穿和自旋极化

研究了电子的自旋相关的隧穿和极化。在外加磁场的作用下，自旋向上的电子与自旋向下的电子具有不同的隧穿系数。当电子的自旋方向与磁场方向相反时，其隧穿概率受到磁场的抑制而变小；反之，当两平行时，电子的了隧穿系数增大。这种差异可以用本中定义的自旋极化率来表示。本对不同磁场下的自旋极化率进行了计算，结果也表明当电子的动能较小，这种自旋极化的效应越显。     

Longitudinal—transverse dynamics of two-component pulses in uniaxial crystals

Based on the Ritz—Whitham variational principle, a set of equations is derived that describe the longitudinal-transverse dynamics of parameters of anelectromagnetic pulse whose ordinary component is a quasi-monochromatic pulse and whose extraordinary component is a videopulse. The critical parameters that determine the pulse stability relative to self-focusing are determined.     

Surface electron states produced by a Rayleigh wave

The electronic properties of a semiconductor bounded by an uneven surface representing an infinitely high potential barrier are investigated. The surface irregularities are produced by a Rayleigh acoustic wave. It is shown that, on the boundary of a semiconductor, surface electron states (waves) may arise whose dispersion laws are obtained under the conditions when conduction electrons are located either in or outside the field of the acoustic wave. Existence domains of surface electron states are found that are distinguished by their physical properties. These domains are separated by a band gap whose width is determined by the height of irregularities.     

Generalizations of the finite nonperiodic Toda lattice and its Darboux transformation

In this paper, we construct Hamiltonian systems for 2 N particles whose force depends on the distances between the particles. We obtain the generalized finite nonperiodic Toda equations via a symmetric group transformation. The solutions of the generalized Toda equations are derived using the tau functions. The relationship between the generalized nonperiodic Toda lattices and Lie algebras is then be discussed and the generalized Kac-van Moerbeke hierarchy is split into generalized Toda lattices, whose integrability and Darboux transformation are studied.     

Phase retrieval of non-continuous fringe patterns by a genetic data reduction algorithm

In this work we focus on the possibilities of recovering the phase from a single fringe pattern that do not have a fringe order sequence or whose fringes are broken. The phase is obtained with a polynomial fitting method whose coefficients are calculated with a genetic algorithm technique that constrains the smoothness of the solutions of a merit function. It is explained how conjugate gradient methods fail in the solution of the proposed merit function. Experimental results are presented using discontinuous fringe patterns obtained from a grazing incidence interferometer while testing a polishing tool.     

Resonant x-ray diffraction studies on the charge ordering in magnetite

Here we show that the low temperature phase of magnetite is associated with an effective, although fractional, ordering of the charge. Evidence and a quantitative evaluation of the atomic charges are achieved by using resonant x-ray diffraction (RXD) experiments whose results are further analyzed with the help of ab initio calculations of the scattering factors involved. By confirming the results obtained from x-ray crystallography we have shown that RXD is able to probe quantitatively the electronic structure in very complex oxides, whose importance covers a wide domain of applications.     

Emergent polarization singularities

Polarization singularities are shown to emerge spontaneously from the incoherent addition of uncorrelated optical fields that individually need not contain singularities. Examples of this phenomenon are given for both vector and ellipse fields. The incoherent addition of vector fields whose singularities have integer winding numbers is shown to yield fields whose singularities have half-integer winding numbers. These findings are used to make predictions about the singularities of the polarized component of the cosmic microwave background.     

A Time-Dependent Born–Oppenheimer Approximation with Exponentially Small Error Estimates

We present the construction of an exponentially accurate time-dependent Born–Oppenheimer approximation for molecular quantum mechanics. We study molecular systems whose electron masses are held fixed and whose nuclear masses are proportional to ε⁻⁴, where ε is a small expansion parameter. By optimal truncation of an asymptotic expansion, we construct approximate solutions to the time-dependent Schr?dinger equation that agree with exact normalized solutions up to errors whose norms are bounded by , for some C and γ >0. Received: 13 February 2001 / Accepted: 13 July 2001     

Limit Sets of Cellular Automata Associated to Probability Measures

We introduce the concept of limit set associated to a cellular automaton (CA) and a shift invariant probability measure. This is a subshift whose forbidden blocks are exactly those, whose probabilities tend to zero as time tends to infinity. We compare this probabilistic concept of limit set with the concepts of attractors, both in topological and measure-theoretic sense. We also compare this notion with that of topological limit set in different dynamical situations.     

On one-dimensional integrable quantum systems with infinitely many degrees of freedom

We study one-dimensional quantum systems whose S-operator conserves the incoming momenta and particle identities. A survey of systems with known S-operators and an approach for solving them rigorously are presented, and several problems and conjectures are formulated. Subsequently, this approach is used to arrive at relativistic dynamics whose S-operators are those of the Ising model in the scaling limit and of the Federbush model. An invariance property of the wave and scattering operators is discovered and argued to hold at the classical level, too.     

Quantum entanglement in the multiverse

We show that the quantum state of a multiverse made up of classically disconnected regions of the space-time, whose dynamical evolution is dominated by a homogeneous and isotropic fluid, is given by a squeezed state. These are typical quantum states that have no classical counterpart and therefore allow analyzing the violation of classical inequalities as well as the EPR argument in the context of the quantum multiverse. The thermodynamical properties of entanglement are calculated for a composite quantum state of two universes whose states are quantum-mechanically correlated. The energy of entanglement between the positive and negative modes of a scalar field, which correspond to the expanding and contracting branches of a phantom universe, are also computed.     

Modular Constraints on Calabi-Yau Compactifications

We derive global constraints on the non-BPS sector of supersymmetric 2d sigma-models whose target space is a Calabi-Yau manifold. When the total Hodge number of the Calabi-Yau threefold is sufficiently large, we show that there must be non-BPS primary states whose total conformal weights are less than 0.656. Moreover, the number of such primary states grows at least linearly in the total Hodge number. We discuss implications of these results for Calabi-Yau geometry.