Frobenius pour les sommes de Selberg

Sans résumé

---

     

A Cholesky dual method for proximal piecewise linear programming

Summary. A quadratic programming method is given for minimizing a sum of piecewise linear functions and a proximal quadratic term, subject to simple bounds on variables. It may be used for search direction finding in nondifferentiable optimization algorithms. An efficient implementation is described that updates a Cholesky factorization of active constraints and provides good accuracy via iterative refinement. Numerical experience is reported for some large problems. Received March 29, 1993 / Revised version received December 18, 1993     

Facial reduction in partially finite convex programming

We consider the problem of minimizing an extended-valued convex function on a locally convex space subject to a finite number of linear (in)equalities. When the standard constraint qualification fails a reduction technique is needed to derive necessary optimality conditions. Facial reduction is usually applied in the range of the constraints. In this paper it is applied in the domain space, thus maintaining any structure (and in particular lattice properties) of the underlying domain. Applications include constrained approximation and best entropy estimation.Research partially supported by the Natural Sciences and Engineering Research Council of Canada.     

Series expansions for functional differential equations

In this paper we prove convergence results for the series expansion of the solution to a linear functional differential equation. The results are consequences of an analysis of eigenfunction expansions for the generator of the solution map. This abstract approach unifies the treatment of retarded and neutral functional differential equations.The research of S.M. Verduyn Lunel has been made possible by a fellowship of the Royal Netherlands Academy of Arts and Sciences     

On a nonlinear hyperbolic problem arising in two-phase flows in naturally fractured reservoirs

A system of two first-order quasilinear equations consisting of one nonhomogenous hyperbolic conservation law and an ordinary differential equation is investigated in two spatial dimensions. The initial boundary-value problem is solved for the system and existence, uniqueness, and stability theorems are proved. We also obtain a result on the behavior of the solution when time goes to infinity which agrees with practical experience. These results offer mathematical validation to computer models in current usage for the numerical simulation of multiphase flow in naturally fractured reservoirs.     

宽波段多步激发K_2-系统产生的钾原子高位态辐射

本文首次报道以690.0～715.0nm宽波段范围内任何波长的脉冲染料激光激发K_2—K系统,由高位钾分子与钾原子碰撞以及分子-原子的混合激发等过程而产生钾原子404.4,404.7和470.05～590.0nm波段内高位态辐射的实验结果,并对激发机制进行了探讨.     

REACTION KINETICS OVER PRECIPITATED Fe/Mn/K CATALYST FOR THE FISCHER-TROPSCH SYNTHESIS

The kinetics of the Fischer-Tropsch Synthesis reaction is studied in an internally recycled reactor (CSTR) over a commercial, precipitated Fe/Mn/K catalyst. Kinetic data are obtained with 1 47-4.04 H2/CO feed gas over a temperature range of 265-320℃, a pressure range of 1.0-2.6 MPa, and a space velocity range of 300-800 h-1 . The kinetic model which fits the experimental data well is the same as that of the intrinsic kinetics, i.e. -RH2 CO=kPH2PCO/(PCO bPH2O, where k is the kinetic constant for the rate-determining step and b is a function of temperature only. This model may be derived by assuming that the rate-determining step is the hydrogenation of adsorbed CO according to the enol mechanism. It is found that the CO usage ratio is probably independent of synthesis gas conversion and total pressure, and the catalyst shows high water-gas-shift activity.