近红外KTP单共振光参量振荡器

本文报道了角度调谐KTP单共振参量振荡器(SRO)的实验结果,并对结果进行了分析讨论.采用调QNd:YAG激光的二次谐波作为泵浦源.受腔镜涂膜带宽的限制,调谐范围为785～1010nm.最大的参量光脉冲能量为2.4mJ.最大的能量转换效率为26.3%.     

On a Problem of Statistical Inference in Null Recurrent Diffusions

We consider a particular example of statistical inference in null recurrent one-dimensional diffusions. In a first parametric model, we prove local asymptotic mixed normality (LAMN) and efficiency of the sequence of maximum likelihood estimates (MLE): its speed of convergence is n ^/2 with ranging over (0, 1). In a second semiparametric model (where in addition an unknown nuisance function with known compact support is included in the drift), we prove a local asymptotic minimax bound and specify asymptotically efficient estimates for the unknown parameter.     

Pivot rules for linear programming: A survey on recent theoretical developments

The purpose of this paper is to discuss the various pivot rules of the simplex method and its variants that have been developed in the last two decades, starting from the appearance of the minimal index rule of Bland. We are mainly concerned with finiteness properties of simplex type pivot rules. Well known classical results concerning the simplex method are not considered in this survey, but the connection between the new pivot methods and the classical ones, if there is any, is discussed.In this paper we discuss three classes of recently developed pivot rules for linear programming. The first and largest class is the class of essentially combinatorial pivot rules including minimal index type rules and recursive rules. These rules only use labeling and signs of the variables. The second class contains those pivot rules which can actually be considered as variants or generalizations or specializations of Lemke's method, and so they are closely related to parametric programming. The last class has the common feature that the rules all have close connections to certain interior point methods. Finally, we mention some open problems for future research.On leave from the Eötvös University, Budapest, and partially supported by OTKA No. 2115.     

Strong unicity and alternation for linear optimization

We consider linear semi-infinite optimization problems and prove characterizations for strong unicity. One of these is a weak alternation property. This result suggests the introduction of the property of regular strong unicity, which is equivalent to a stronger alternation property. The theorems are used in order to prove a Haar-type theorem for linear optimization problems. An application to best Chebyshev approximation is given.Communicated by A. V. Fiacco     

Nonlinear interactions between drift waves and zonal flows

Phase coherent interactions between drift waves and zonal flows are considered. For this purpose, mode coupling equations are derived by using a two-fluid model and the guiding center drifts. The equations are then Fourier analyzed to deduce the nonlinear dispersion relations. The latter depict the excitation of zonal flows due to the ponderomotive forces of drift waves. The flute-like zonal flows with insignificant density fluctuations have faster growth rates than those which have a finite wavelength along the magnetic field direction. The relevance of our investigation to drift wave driven zonal flows in computer simulations and laboratory plasmas is discussed. Received 5 April 2002 Published online 28 June 2002     

An Alternate Method to the Alternating Time-Frequency Method

A variational approach is developed which permits the calculation of thesteady-state time domain response of nonlinear ordinary differentialequations (ODE). Unlike numerical integration, transient calculationsare avoided and unlike harmonic balance, all calculations are performedin a single domain, namely the time domain. The relationships areestablished between the developed method and existing techniques such asfinite element in time (FET), standard finite differences (FD) and theharmonic balance method (HBM). The proposed technique also includes anarclength continuation algorithm allowing efficient parametric studiesto be performed. Local stability of the solutions is also assessed.     

Acousto-optic amplitude modulation and demodulation of electromagnetic wave in magnetised diffusive semiconductors

Using hydrodynamical model of semiconductor plasma analytical investigations are made for the amplitude modulation as well as demodulation of an electromagnetic wave in a transversely magnetised acousto-optic semiconducting plasma. The inclusion of carriers diffusion adds new dimension in the analysis presented here. Analysis are made under different wave number regions over a wide range of cyclotron frequency. It has been seen that diffusion of charge carriers modifies amplitude modulation and demodulation processes effectively. Numerical estimations are made for n-InSb crystal irradiated by pump wave of frequency 1.6 T s^-1. Complete absorption of the waves takes place in all the possible wave lengths regimes when the cyclotron frequency becomes exactly equal to (v ² + )^1/2. Received 28 February 2002 Published online 19 July 2002     

On the optimal value function for certain linear programs with unbounded optimal solution sets

Often, the coefficients of a linear programming problem represent estimates of true values of data or are subject to systematic variations. In such cases, it is useful to perturb the original data and to either compute, estimate, or otherwise describe the values of the functionf which gives the optimal value of the linear program for each perturbation. If the right-hand derivative off at a chosen point exists and is calculated, then the values off in a neighborhood of that point can be estimated. However, if the optimal solution set of either the primal problem or the dual problem is unbounded, then this derivative may not exist. In this note, we show that, frequently, even if the primal problem or the dual problem has an unbounded optimal solution set, the nature of the values off at points near a given point can be investigated. To illustrate the potential utility of our results, their application to two types of problems is also explained.This research was supported, in part, by the Center for Econometrics and Decision Sciences, University of Florida, Gainesville, Florida.The author would like to thank two anonymous reviewers for their most useful comments on earlier versions of this paper.     

An O(n) algorithm for quadratic knapsack problems

An algorithm is presented which solves bounded quadratic optimization problems with n variables and one linear constraint in at most O(n) steps. The algorithm is based on a parametric approach combined with well-known ideas for constructing efficient algorithms. It improves an O(n log n) algorithm which has been developed for a more restricted case of the problem.     

On the differentiability of optimal values for bounded nonlinear programs with equality constraints

We consider a parametrized family of nonlinear programs where the feasible region is defined by equality constraints in a ball. The global optimal value is shown to be twice continuously differentiable over an open and dense set in the perturbation parameter space.