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  • 2020-2023  (1)
  • 2015-2019  (1)
  • 1985-1989  (2)
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  • 1
    facet.materialart.
    Unknown
    Economic Development in Papua New Guinea: The New Orthodoxy: Review Article (1986)
    Honolulu, etc. : Periodicals Archive Online (PAO)
    Pacific Affairs. 59:3 (1986:Fall) 476 
    Details
    ISSN: 0030-851X
    Topics: Political Science , Sociology , Economics
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:5082-1986-059-03-000005
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Statistical graphics in geochemical journals (1987)
    Springer
    Mathematical geology 19 (1987), S. 1-24 
    Details
    ISSN: 1573-8868
    Keywords: mathematical geology ; statisics ; statistical graphics ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A quantitative investigation of types of statistical graphics and maps being used for presentation of geochemical data has been made for the 1984 volumes ofGeochemica et Cosmochimica Acta, Chemical Geology, Contributions to Mineralogy and Petrology, Geochemistry International, Journal of Geochemical Exploration, Journal of Petrology, and the 1983 volume ofOrganic Geochemistry. Although a number of significant differences exist between relative proportions of text, tables, statistical graphs and maps, and other illustrations in the various journals, overall figures are comparable broadly to those found by Cleveland (1984) in a recent survey of usage in 57 journals in natural, mathematical, and social sciences. Between 18% and 35% of 1463 graphs and maps in these journals contain at least one item of error or poor presentation, indicating the need for substantial improvement in both standards of preparation and refereeing of diagrams, and we suggest guidelines for both authors and referees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275431
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Unknown
    Adaptive Cut Selection in Mixed-Integer Linear Programming (2022)
    Details
    Publication Date: 2022-08-08
    Description: Cut selection is a subroutine used in all modern mixed-integer linear programming solvers with the goal of selecting a subset of generated cuts that induce optimal solver performance. These solvers have millions of parameter combinations, and so are excellent candidates for parameter tuning. Cut selection scoring rules are usually weighted sums of different measurements, where the weights are parameters. We present a parametric family of mixed-integer linear programs together with infinitely many family-wide valid cuts. Some of these cuts can induce integer optimal solutions directly after being applied, while others fail to do so even if an infinite amount are applied. We show for a specific cut selection rule, that any finite grid search of the parameter space will always miss all parameter values, which select integer optimal inducing cuts in an infinite amount of our problems. We propose a variation on the design of existing graph convolutional neural networks, adapting them to learn cut selection rule parameters. We present a reinforcement learning framework for selecting cuts, and train our design using said framework over MIPLIB 2017. Our framework and design show that adaptive cut selection does substantially improve performance over a diverse set of instances, but that finding a single function describing such a rule is difficult. Code for reproducing all experiments is available at https://github.com/Opt-Mucca/Adaptive-Cutsel-MILP.
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/pdf
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    OPUS
  • 4
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    Controlling transient gas flow in real-world pipeline intersection areas (2019)
    Details
    Publication Date: 2023-07-14
    Description: Compressor stations are the heart of every high-pressure gas transport network. Located at intersection areas of the network they are contained in huge complex plants, where they are in combination with valves and regulators responsible for routing and pushing the gas through the network. Due to their complexity and lack of data compressor stations are usually dealt with in the scientific literature in a highly simplified and idealized manner. As part of an ongoing project with one of Germany's largest Transmission System Operators to develop a decision support system for their dispatching center, we investigated how to automatize control of compressor stations. Each station has to be in a particular configuration, leading in combination with the other nearby elements to a discrete set of up to 2000 possible feasible operation modes in the intersection area. Since the desired performance of the station changes over time, the configuration of the station has to adapt. Our goal is to minimize the necessary changes in the overall operation modes and related elements over time, while fulfilling a preset performance envelope or demand scenario. This article describes the chosen model and the implemented mixed integer programming based algorithms to tackle this challenge. By presenting extensive computational results on real world data we demonstrate the performance of our approach.
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/pdf
    Format: application/pdf
    Format: application/pdf
    Library Location Call Number Volume/Issue/Year Availability
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    OPUS
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