Postan - A Package for Postoptimal Analysis (An Extension of Minos)

This paper presents a new software package which has been developed in collaboration with IIASA The new package, POSTAN, is designed for postoptimal analysis of linear programming problems, and is embedded in the well-known linear and nonlinear programming code MINOS. POSTAN is composed of a number of FORTRAN subroutines which may be called by adding some new keywords to the original list of MINOS specifications. The main function of POSTAN is to determine the ranges in which certain parameters may be changed without affecting the optimal solution and/or the optimal basis. In this paper the authors outline the general form of the linear programming problems studied, describe the six new subroutines in some detail, and illustrate this description with a printout obtained in the solution of a sample problem. The mathematical theory behind the software package is given in an Appendix

Alternative Routes from Fossil Resources to Chemical Feedstocks

The chemical industry depends very heavily on hydrocarbon feedstocks, which are presently derived almost exclusively from crude oil. Although only about seven percent of the hydrocarbons suitable for chemical processing are actually used in this way, it is already clear that there is a potential conflict between the needs of the energy sector and those of the chemical industry: they are competing for increasingly scarce liquid hydrocarbon resources. The authors suggest that the supply of hydrocarbon feedstocks to the chemical industry could be protected against the effects of changing patterns of energy use by modifying the underlying industrial structure. They have developed an approach which takes a variety of production processes (either in use or under development), compares their efficiency their consumption of different resources, etc., and finds the combination of technologies that best satisfies a particular demand while staying within the limits imposed by resource availability. This approach uses the techniques of interactive decision analysis to incorporate the unquantifiable social and political factors that must influence any development decision. By way of illustration, the method is applied to one very small part of the problem area: the different routes to the production of methanol. This report does not attempt to provide any final answer to the problem of feedstock supply, but rather to explain one possible approach to the problem and discuss some intermediate results. It is addressed not only to researchers, but also, and in particular, to all decision makers and industrial consultants facing problems of this type

Postan 3 - Extended Postoptimal Analysis Package for Minos

This paper is one of the series of 11 Working Papers presenting the software for interactive decision support and software tools for developing decision support systems. These products constitute the outcome of the contracted study agreement between the System and Decision Sciences Program at IIASA and several Polish scientific institutions. The theoretical part of these results is presented in the IIASA Working Paper WP-88-071 entitled "Theory, Software and Testing Examples in Decision Support Systems" which contains the theoretical and methodological backgrounds of the software systems developed within the project. This paper presents the POSTAN 3 package. This package constitutes the tool for postoptimal analysis for linear and linear-fractional programming problems. POSTAN consists of a number of FORTRAN routines which are incorporated into MINOS, the well known linear and nonlinear programming code developed at the Stanford University. The postoptimal analysis is performed after MINOS has found an optimal solution and is initiated by extending the original MINOS specification file. The main function of POSTAN is ranging with respect to parameters specified by the user and computing the sensitivity coefficients

Generating Efficient Alternatives for Development in the Chemical Industry

Industrial development can be seen as the process of changing the production structure by means of investment over the course of time. To control this development to the benefit of society while maintaining the profitability of the industry, decision makers must learn how socioeconomic changes and market conditions affect the static and dynamic properties of the production structure. This paper reports on the progress of collaborative research into the design of tools which could help decision makers to control development in the chemical industry. The basic approach is to formulate a model of the equilibrium state of the industry or, in the case considered here, of a particular subsector of the industry. The development process is initially described by a static multiobjective optimization problem, from which a dynamic multiobjective optimization problem is then derived. An example illustrating the use of this method for the pesticide-producing sector is given. The optimization problem and method for controlling industrial development put forward in this paper were worked out as part of the research program on Growth Strategy Optimization Systems (GSOS), sponsored by the Ministry of the Chemical Industry in Poland. This program is actually carried out at the Institute for Control and Systems Engineering (ICSE), part of the Academy of Mining and Metallurgy (AMM) in Cracow. The multiobjective optimization method for generating efficient alternatives and the related software were developed by the System and Decision Sciences Area at IIASA. This collaborative research was carried out within the framework of the agreement on scientific cooperation cosigned by IIASA and the AMM in June 1980

Metabolome Analysis of the Interaction Between Perennial Ryegrass (\u3cem\u3eLolium Perenne\u3c/em\u3e) and the Fungal Endophyte \u3cem\u3eNeotyphodium Lolii\u3c/em\u3e

Perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.) frequently contain endophytic fungi (Neotyphodium lolii in perennial ryegrass and N. coenophialum in tall fescue). The presence of the endophyte has been shown to improve seedling vigour, persistence and drought tolerance in marginal environments as well as provide protection against some insect pests. Endophyte-infected grasses also produce a wide range of metabolites, including ergopeptine alkaloids, indole-isoprenoid lolitrems, pyrrolizidine alkaloids, and pyrrolopyrazine alkaloids. In contrast to information on alkaloids and animal toxicosis, the beneficial physiological aspects of the endophyte/grass interactions have not been well characterised. The physiological mechanisms which lead to increased plant vigour and enhanced tolerance to abiotic stresses unrelated to the reduction in pest damage to endophyte-infected grasses are unknown. Recent technological advances in metabolomics enable dynamic changes in the metabolome of an organism under varying experimental conditions to be studied. This provides opportunities for the investigation and validation of each and every detected metabolite, investigation of known metabolic pathways through searching of databases of known metabolites, molecular formula determination of unknown metabolites and creation of pathways from novel metabolites

Radiation from Excited Vortex in the Abelian Higgs Model

Excitation of a vortex in the Abelian Higgs model is investigated with the help of a polynomial approximation. The excitation can be regarded as a longitudinal component of the vector field trapped by the vortex. The energy and profile of the excitation are found. Back-reaction of the excitation on the vortex is calculated in the small $\kappa$ limit. It turns out that in the presence of the excitation the vortex effectively becomes much wider - its radius oscillates in time and for all times it is not smaller than the radius of the unexcited vortex. Moreover, we find that the vector field of the excited vortex has long range radiative component. Bound on the amplitude of the excitation is also found.Comment: Latex, 20 pages. 2 figures attached as .uu file to be decoded and used as input for epsfbox command which is already included in the main Latex fil

Fission Fragment Mass and Kinetic Energy Yields of Fermium Isotopes

A rapidly converging 4-dimensional Fourier shape parametrization is used to model the fission process of heavy nuclei. Potential energy landscapes are computed within the macroscopic-microscopic approach, on top of which the multi-dimensional Langevin equation is solved to describe the fission dynamics. Charge equilibration at scission and de-excitation by neutron evaporation of the primary fragments after scission is investigated. The model describes various observables, including fission-fragment mass, charge, and kinetic energy yields, as well as post-scission neutron multiplicities and, most importantly, their correlations, which are crucial to unravel the complexity of the fission process. The parameters of the dynamical model were tuned to reproduce experimental data obtained from thermal neutron-induced fission of $^{235}$U, which allows us to discuss the transition from asymmetric to symmetric fission along the Fm isotopic chain.Comment: Presented at the Mazurian Lakes Conference on Physics, 2023, Polan