On the Problem of Designing Matrix Generators

One of the main difficulties which arises when using a general purpose linear programming (LP) package is the need to prepare a special code to transform initially structured model data into a format appropriate for subsequent use by an LP solution system (for example, at IIASA we require an MPS-type input file for use with the MINOS LP system). These codes are usually in general purpose programming languages, are often rather complex, and are generally quite difficult to implement. There is a lack of advanced software capable of simplifying the preparation of information in the form required by the LP package, and this is a problem especially for those who use linear models in the solution of a wide variety of applied problems. In such cases it is highly desirable to have a flexible and convenient interface between user and LP software. Here we describe a tool which saves time for the analyst by making it possible to organize investigations with linear models in an interactive manner

Revised Version of the SOVAM

Understanding the nature and dimensions of the world food problem and the policies available to alleviate it has been the focal point of IIASA's Food and Agriculture Program (FAP) since it began in 1977. National food systems are highly interdependent, and yet the major policy options exist at the national level. Therefore, to explore these options, it is necessary both to develop policy models for national economies and to link them together by trade and capital transfers. Over the years FAP has, with the help of a network of collaborating institutions, developed and linked national policy models of twenty countries, which together account for nearly 80 percent of important agricultural attributes such as area, production, population, exports, imports and so on. The remaining countries are represented by 14 somewhat simpler models of groups of countries. The countries constituting the Council of Mutual Economic Assistance (CMEA) together are a major influence on the world market. An aggregate food and agriculture model of the CMEA, in which the CMEA is treated as one nation has been developed by the FAP, as part of the IIASA/FAP basic linked system. In addition, development of detailed models for some of the major nations constituting the CMEA was undertaken. The development of the Soviet Agricultural Model (SOVAM) was started in late 1983 in collaboration with a number of institutions in the Soviet Union. These include the All-Union Research Institute of Cybernetics in Agriculture, the Computer Center of the USSR Academy of Sciences, the All-Union Research Institute for Systems Studies, and the Central Economic Mathematical Institute. In this paper Vladimir Iakimets and Vladimir Lebedev describe a revised version of the SOVAM

Relativistic Laser-Matter Interaction and Relativistic Laboratory Astrophysics

The paper is devoted to the prospects of using the laser radiation interaction with plasmas in the laboratory relativistic astrophysics context. We discuss the dimensionless parameters characterizing the processes in the laser and astrophysical plasmas and emphasize a similarity between the laser and astrophysical plasmas in the ultrarelativistic energy limit. In particular, we address basic mechanisms of the charged particle acceleration, the collisionless shock wave and magnetic reconnection and vortex dynamics properties relevant to the problem of ultrarelativistic particle acceleration.Comment: 58 pages, 19 figure

Formation of Iron Silicides Under Graphene Grown on the Silicon Carbide Surface

The formation of iron silicide thin films under graphene grown on the silicon carbide surface is investigated. The thin films are synthesized by consecutive intercalation of iron and silicon atoms into the graphene. Experiments are carried out in situ in ultrahigh vacuum. The elemental composition and chemical state of the surface of prepared samples and their atomic structure are determined by low energy electron diffraction and high resolution X ray photoelectron spectroscopy using synchrotron radiation. The thickness of deposited iron and silicon layers varies in the range of 0.1 2 nm, and the sample annealing temperature is varied from room temperature to 600 C. We show that intercalation of silicon into the graphene Fe SiC system leads to the formation of a layer of Fe Si solid solution coated with the surface silicide Fe3Si. The films are effectively protected by graphene from exposure to ambient environment, which opens possibilities for their practical applicatio