User Guide to a Mathematical Programming Package for Multicriteria Dynamic Linear Problems Hybrid Version 3.1

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 system developed within the project. This paper presents the HYBRID system for solving linear multiple criteria optimization problems, utilizing the reference point technique. This method, originally developed by the authors, is the non-simplex one and is based on the augmented Lagrangian technique with conjugate gradient optimization. Due to special properties of the method it was possible to make the implementation especially efficient for solving dynamic problems. In such cases the HYBRID outperforms such known packages, like MINOS. Since the method does not require to store large amount of information (like basis matrix in standard Simplex formulation) it is especially valuable for microcomputer applications, allowing to solve problems a magnitude bigger dimensionality than with standard methods

Implementation of an Algorithm for Scaling Matrices and Other Programs Useful in Linear Programming

Matrix scaling is an operation in which the rows and columns of a matrix are multiplied by positive scalars such that the elements of the scaled matrix are similar in absolute magnitude. This can be very important when dealing with models in which matrix elements can take a wide range of values, especially since certain mathematical codes, such as MINOS, require that the absolute values of all non-zero elements should be "reasonably" close to one. This paper describes the implementation of an optimal scaling method proposed by Curtis and Reid. The algorithm is outlined and a users' guide to the program implemented on the VAX at IIASA is given. (The scaling algorithm has been linked to the MINOS package at IIASA by Zenon Fortuna, who has also developed a rescaling routine linked to this package.) Two other programs useful in linear programming are also described: the first is designed to print out a matrix by rows, and also gives diagnostic aid; the second makes it possible to merge up to five LP models into one, generating a resultant MPSX file that may be used to solve multicriteria problems

A Mathematical Programming Package for Multicriteria Dynamic Linear Problems HYBRID. Methodological and User Guide to Version 3.03

One of the main problems in development the decision support software is the availability of efficient optimization algorithms. These algorithms, when applied in decision support systems should possess several criteria -- like robustness, efficiency, high speed and low memory requirements. Moreover, the special structure of the optimization problem arising in such applications should be taken into account. All these facts motivated the System and Decision Sciences Program to investigate all these topics. This paper presents the result of such collaborative effort. The HYBRID system, developed in the Institute of System Research of the Polish Academy of Sciences is the implementation of original, non simplex algorithm especially suited for solving dynamic multiple criteria problem. Except of high efficiency, this algorithm is especially interesting for microcomputers with small available memory. This research is being performed upon a contracted study agreement between the International Institute for Applied Systems Analysis and the Polish Academy of Sciences

HYBRID - A Mathematical Programming Package

This paper describes a new mathematical programming package developed by the authors and implemented both on the VAX at IIASA and at the Computing Center of the State Planning Commission in Warsaw. The new package, called HYBRID, is designed for the solution of linear programming problems, making use of a particular implementation of the Lagrange multiplier method. The version described here is limited to static LP problems (including multiobjective problems that may be reformulated as LP problems), but it will eventually be extended to deal with dynamic problems. HYBRID is intended for use with real-world problems that require scenario analysis. and is therefore oriented towards an interactive mode of operation in which a sequence of problems is to be solved under different conditions (e.g., with different objective functions, reference points, constraints or bounds). This report provides all the information necessary to use the HYBRID package at IIASA and also discusses the methodological issues associated with the chosen solution technique

Coordination of Sectoral Production Planning Using Prices and Quotas (A Case Study for the Polish Agricultural Model)

Understanding the nature and dimensions of the world food problem and the policies available to alleviate it has been the focal point of the IIASA Food and Agriculture Program 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. For greater realism the models in this scheme are being kept descriptive, rather than normative. In the end it is proposed to link models to twenty countries, which together account for nearly 80 per cent of important agricultural attributes such as area, production, population, exports, imports and so on. As part of the development of the Polish Agricultural Model, Marek Makowski and Janusz Sosnowski have investigated the coordination of sectoral production planning in Poland. Since this work involved methodological innovations, it was carried out in joint collaboration with the Food and Agriculture Program (FAP) and the Systems and Decision Sciences Area of IIASA. This paper presents intermediate results of research done within the framework of the elaboration of the Polish Agricultural model, which will not only be included in the system of models of the FAP, but will also be used for decision-making processes in Poland

Adolescent Expressive Reluctance Exacerbates Risk for Substance Use Following Daily Hassles

Previous research has established a link between adolescent’s perceived daily hassles and subsequent adjustment, but less is known about factors that exacerbate this relationship. The purpose of the present study was to identify if adolescent’s reluctance to express emotions moderated the association between their perceived daily hassles and subsequent substance use (i.e., alcohol, marijuana, tobacco). Cross-sectional data were obtained from a larger study that examined the effects of exposure to community violence among low-income, urban adolescents (N = 260, Mage = 14.14, SD = 1.62 years; 92% African American; 54% female). Linear regression analyses controlling for adolescent age, biological sex, and previous levels of drug use and daily hassles revealed that expressive reluctance moderated the association between perceived daily hassles and adolescent substance use. Specifically, for adolescents who were least likely to express their emotions, increases in perceived daily hassles were associated with significant increases in substance use. Further examination of domain-specific hassles revealed that expressive reluctance moderated the effects of academic, parental, and general neighborhood hassles on drug use, while no significant effects were detected for hassles related to friends or neighborhood danger. The present findings clarify which perceived daily hassles adversely affect adolescents, and how emotional expression can play an integral role in determining risk for poor coping behaviors.https://scholarscompass.vcu.edu/uresposters/1280/thumbnail.jp

Survival of Phoma koolunga, a causal agent of ascochyta blight, on field pea stubble or as pseudosclerotia in soil

Phoma koolunga is a recently recognized pathogen in the ascochyta blight complex of field pea (Pisum sativum). Unlike the other three ascochyta blight pathogens, survival of P. koolunga is poorly understood. Survival of this fungus was examined on field pea stubble and as pseudosclerotia on the surface of, and buried in, field soil. Pseudosclerotia were formed in plates containing potato dextrose agar (PDA) mixed with sand or amended with fluorocytocin. After 1 month, P. koolunga was recovered on amended PDA from 93% of stubble sections retrieved from the soil surface, 36% of buried stubble sections and 100% of pseudosclerotia buried in field soil, pasteurized or not. The frequency of recovery of P. koolunga decreased over time and the fungus was not recovered from stubble on the soil surface at 15 months, nor was it recovered from stubble buried in soil at 11 months or later, or from pseudosclerotia buried for 18 months. In a pot bioassay, most ascochyta blight lesions developed on plants inoculated with stubble retrieved from the soil surface after 1 month. Infectivity of the inoculum decreased over time. Disease on plants inoculated with stubble that had been buried or left on the soil surface for up to 6 and 5 months, respectively, and pseudosclerotia retrieved at 14 months and later from field soil did not differ from the non-inoculated control. These results suggest that field pea stubble may play a role in survival of P. koolunga, especially if it remains on the soil surface. In addition, pseudosclerotia were able to persist in soil and infect field pea plants into the next season.M. Khani, J. A. Davidson, M. R. Sosnowski and E. S. Scot

Survival, transmission and control of Phoma koolunga in field pea seed and reaction of field pea genotypes to the pathogen

Little is known about the epidemiology of Phoma koolunga, a component of the ascochyta blight complex of field pea in southern Australia. The aims of this research were to investigate seed infection, efficacy of fungicides as seed dressings and the reaction of current field pea genotypes to this fungus. The frequency of isolation of P. koolunga from individual seed samples from South Australia, Victoria and Western Australia ranged from 0 to 6 %. Disease was transmitted to 98% of seedlings that emerged from artificially inoculated seeds (AIS) in growth room conditions. The necrotic index on seedlings that emerged from AIS at 8°C was greater than that for seedlings at 12, 16 and 20°C. P-Pickel T® and Jockey Stayer® were the most effective fungicides for reducing disease incidence and severity on seedlings emerged from AIS sown in soil and on germination paper, respectively. The response of 12 field pea genotypes to one isolate of P. koolunga was assessed by spraying plants with pycnidiospore suspension in controlled conditions and examining symptoms from 3 to 21 days post-inoculation (dpi). Genotypes Sturt, Morgan and Parafield showed more severe disease on the lowest three leaves than the other genotypes at 21 dpi. In another experiment, four genotypes of short, semi-leafless type field peas were inoculated with three isolates of P. koolunga which differed in virulence and assessed as described above. Kaspa showed significantly less disease than Morgan or WAPEA2211 at 21 dpi when inoculated with two of the three isolates tested. Isolates of P. koolunga differed in aggressiveness based on % leaf area diseased until 14 dpi, but differences were not significant at 21 dpi.M. Khani, J. A. Davidson, M. R. Sosnowski, E. S. Scot