Modeling the lossy transmission of correlated sources in multiple access fading channels

In this paper, we develop accurate distortion models for the lossy transmission of two correlated sources in a multiple access Rayleigh fading channel. We focus on a class of real-life communication systems, where the source and channel coders have already been designed separately and can only be configured during the system operation. We investigate three different source coding schemes: distributed source coding (DSC), layered source coding, and independent compression through quantization. With the later scheme the sources are jointly decoded with minimum mean square error (MMSE) estimation at the receiver. We also consider two different transmission schemes: Orthogonal transmissions and interfering transmissions decoded with a successive interference cancellation (SIC) decoder. Our final closed-form analytical models are used to determine the optimal combination of source coding and transmission schemes, as well as their optimal configuration. Hence, we exercise joint source and channel coding (JSCC) by optimizing the system configuration. Through simulations, we first validate the analytical model and illustrate the performance of different schemes. Finally, we demonstrate the JSCC gains achieved by our system.     

磁控溅射法制备二氧化钒薄膜最佳参量的研究

用X射线电子能谱仪(XPS)对不同条件下用磁控溅射法制备的VO₂薄膜进行测试,得到VO₂薄膜内部组成成份的信息.研究了获得高含量VO₂薄膜的最佳制备参量.同时还观察到V₂O₃、VO₂、V₂O₅以接近含量共存的现象,这与以前研究所给出的薄膜几乎只由V₂O₃、VO₂、V₂O₅中的两种组成的结论有所不同.     

On the continuity of a Lagrangian multiplier function in input optimization

We show that a Lagrangian multiplier function in input optimization is generally discontinuous on regions of stability and then we find conditions for its continuity.Research partly supported by the Natural Sciences and Engineering Research Council of Canada.Presented at TIMS/ORSA Meeting in Boston, Massachusetts, April 29-May 1, 1985.The contribution of this author is part of his M.Sc. thesis in Applied Mathematics at McGill University.     

Conjugate direction methods with variable storage

In this paper we study conjugate gradient algorithms for large optimization problems. These methods accelerate (or precondition) the conjugate gradient method by means of quasi-Newton matrices, and are designed to utilize a variable amount of storage, depending on how much information is retained in the quasi-Newton matrices. We are concerned with the behaviour of such methods on the underlying quadratic model, and in particular, with finite termination properties.     

A differential equation approach to nonlinear programming

A new method is presented for finding a local optimum of the equality constrained nonlinear programming problem. A nonlinear autonomous system is introduced as the base of the theory instead of usual approaches. The relation between critical points and local optima of the original optimization problem is proved. Asymptotic stability of the critical points is also proved. A numerical algorithm which is capable of finding local optima systematically at the quadratic rate of convergence is developed from a detailed analysis of the nature of trajectories and critical points. Some numerical results are given to show the efficiency of the method.     

A lower bound for the controlling parameters of the exact penalty functions

The purpose of this paper is to present new exact penalty functions and discuss their properties. A lower bound on the controlling parameters is given, for which above this value, the optimum of the exact penalty function coincides with the optimum of the nonlinear programming problem.This work was supported by the National Research Council of Canada under Grant A4414.     

The fundamental continuity theory of optimization on a compact space. I

Optimizers on a compact feasible region are abstractly specified and, as set-valued mappings, are studied for sufficient conditions yielding them (as well as certain associated maps and certain restrictions of all these) continuous, using function space methods. In particular, the study concerns the continuity of the set of optimal solutions as a function of the three arguments: (i) objective function used, (ii) an incentive (or penalty/reward) function imposed, and (iii) an abstract parameter. An interpretation of the mathematical apparatus is suggested and a brief game-theoretic illustration is given.     

From the main equation to the Klein-Gordon equation

The purpose of this paper is to bring out some connections between the work of Isaacs and physics. The first five sections are devoted to classical dynamics. The theories of Hamilton and Jacobi are revisited via the geometrical approach to optimal control and de Broglie's ideas. The other sections contain a stochastic-type generalization, leading to the Klein-Gordon equation of relativistic wave mechanics.     

On optimizing certain nonlinear convex functions which are partially defined by a simulation process

This paper considers the problem of optimizing a nonlinear convex function which is, in part, defined by a simulation process. An iterative technique, based on contractive mapping properties, is given by which a selected class of such functions can be optimized.