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  • 1
    Electronic Resource
    Electronic Resource
    Stochastic investigations of pseudo-random number generators (1991)
    Springer
    Computing 46 (1991), S. 53-65 
    Details
    ISSN: 1436-5057
    Keywords: 65 C 10 ; Pseudo-random numbers ; sequential transform ; chi-square test ; 3σ-rule ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Im Bewertungs- und Einordnungsprozess von Pseudozufallsgeneratoren mit einer vorausgesetzten Gleichverteilung U[0, 1) verwendet man die in [1] von der Autorin eingeführteSequentielle g-Transformation. Auf diese Weise bekommt man eine diskrete Verteilung, genannt e(g), die unmittelbar zur Untersuchung lokaler Eigenschaften von Pseudozufall-szahlenfolgen dienen kann. Die globalen Eigenschaften dieser Folgen können mittels einiger neu eingeführter “Qualitätsstatistiken” bewertet werden, welche auf der e(g)-Verteilung basieren. Umfangreiche Erfahrungen mit den Qualitätsstatistiken haben uns zur Einführung von zwei numerischen Bewertungen der Generatoren geführt, welche im ArtikelQualität undStabilität genannt werden. Diese können zur globalen Einordnung der Generatoren dienen. Die entwickelen Methoden werden an Hand bekannter und neuer Generatoren vorgestellt.
    Notes: Abstract In the process of evaluation and ranking of pseudo-random number generators with assumed uniform distribution U[0, 1), we apply thesequential g-transformation discussed in the author's preceding paper [1]. Thus, the obtained discrete distribution named e(g) may immediately serve for investigations of local properties of pseudo-random sequences. The global properties of these sequences may be estimated by means of severalquality statistics based on the e(g)-distribution. Extensive experiences with the quality statistics lead to the introduction of two numerical estimates of a generator, calledquality andstability. These may serve for global ranking of generators. The developed methods are illustrated on numerous known and new generators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02239011
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  • 2
    Electronic Resource
    Electronic Resource
    Workload planning in small lot printed circuit board assembly (1997)
    Springer
    OR spectrum 19 (1997), S. 147-157 
    Details
    ISSN: 1436-6304
    Keywords: Key words: production ; scheduling ; printed circuit board assembly ; modelling ; linear programming ; aggregational error ; decision support ; Schlüsselwörter: Produktion ; Ablaufplanung ; Leiterplattenbestückung ; Modellierung ; lineare Programmierung ; Aggregationsfehler ; Entscheidungsunterstützung ; S′jm = Sjm ; SFj(r)(12)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung. Bei der Kleinserienmontage von Leiterplatten besteht das Problem der Einlastungsplanung darin, ein Tagesprogramm an Produktionsaufträgen zusammenzustellen, die gemeinsam in das Produktionssystem eingeschleust werden. Jeder Produktionsauftrag entspricht einem bestimmten Leiterplattentyp. Wechselt man bei der automatischen Bestückung von Leiterplatten zu einem neuen Leiterplattentyp, so fallen erhebliche Rüstzeiten an, die davon abhängen, wie viele Bauteilezuführungen im Magazin der Bestückungsautomaten ausgewechselt werden müssen. Zur Unterstützung dieses Entscheidungsproblems werden zwei unterschiedliche Modelle der linearen Optimierung entwickelt. Die beiden Modelle unterscheiden sich vor allem durch ihren Aggregationsgrad und ihren Rechenaufwand. Zur Verringerung des Aggregationsfehlers wird ein auf der Fuzzy-Set-Theorie beruhender Ansatz zur Abschätzung der bei automatischen SMD-Bestückungsautomanten auftretenden Rüstzeiten entwickelt. Hierbei wird als industrielles Anwendungsbeispiel die Leiterplattenbestückung in einem bedeutenden Elektronikunternehmen betrachtet. Die durchgeführte numerische Untersuchung zeigt, daß das hochaggregierte Fuzzy-LP-Modell zu hinreichend genauen Lösungen führt und erheblich geringeren Rechenaufwand verursacht als ein detaillierteres LP-Modell. Außerdem wird die praktische Eignung des Fuzzy-LP-Modells für den Einsatz innerhalb eines interaktiven Entscheidungsunterstützungssystems verdeutlicht.
    Notes: Abstract. The problem of workload planning in small lot printed circuit board (PCB) assembly concerns the determination of the daily mix of production orders to be released into the production system. When switching from one production order (board type) to another, a considerable set-up time is incurred based on the number of component feeders to be replaced in the component magazine of the assembly machines. To support the order-mix decision faced by a major electronics manufacturer, two versions of a linear programming model are developed. The models differ primarily in their degree of aggregation and their computational effort. In order to reduce the aggregational error incurred, a fuzzy approach is developed to estimate the number of component set-ups at automatic SMD placement machines. Our numerical investigation reveals that sufficiently accurate solutions may be obtained from a highly aggregate fuzzy LP-model and this is achieved with considerably less computational effort than with a more detailed LP-model. We also demonstrate the potential suitability of the fuzzy LP-model for implementation within an interactive decision support system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545517
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  • 3
    Electronic Resource
    Electronic Resource
    Workload planning in small lot printed circuit board assembly (1997)
    Springer
    OR spectrum 19 (1997), S. 147-157 
    Details
    ISSN: 1436-6304
    Keywords: production ; scheduling ; printed circuit board assembly ; modelling ; linear programming ; aggregational error ; decision support ; Produktion ; Ablaufplanung ; Leiterplattenbestückung ; Modellierung ; lineare Programmierung ; Aggregationsfehler ; Entscheidungsunterstützung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung Bei der Kleinserienmontage von Leiterplatten besteht das Problem der Einlastungsplanung darin, ein Tagesprogramm an Produktionsaufträgen zusammenzustellen, die gemeinsam in das Produktionssystem eingeschleust werden. Jeder Produktionsauftrag entspricht einem bestimmten Leiterplattentyp. Wechselt man bei der automatischen Bestückung von Leiterplatten zu einem neuen Leiterplattentyp, so fallen erhebliche Rüstzeiten an, die davon abhängen, wie viele Bauteilezuführungen im Magazin der Bestückungsautomaten ausgewechselt werden müssen. Zur Unterstützung dieses Entscheidungsproblems werden zwei unterschiedliche Modelle der linearen Optimierung entwickelt. Die beiden Modelle unterscheiden sich vor allem durch ihren Aggregationsgrad und ihren Rechenaufwand. Zur Verringerung des Aggregationsfehlers wird ein auf der Fuzzy-Set-Theorie beruhender Ansatz zur Abschätzung der bei automatischen SMD-Bestückungsautomanten auftretenden Rüstzeiten entwickelt. Hierbei wird als industrielles Anwendungsbeispiel die Leiterplattenbestückung in einem bedeutenden Elektronikunternehmen betrachtet. Die durchgeführte numerische Untersuchung zeigt, daß das hochaggregierte Fuzzy-LP-Modell zu hinreichend genauen Lösungen führt und erheblich geringeren Rechenaufwand verursacht als ein detaillierteres LP-Modell. Außerdem wird die praktische Eignung des Fuzzy-LP-Modells für den Einsatz innerhalb eines interaktiven Entscheidungsunterstützungssystems verdeutlicht.
    Notes: Abstract The problem of workload planning in small lot printed circuit board (PCB) assembly concerns the determination of the daily mix of production orders to be released into the production system. When switching from one production order (board type) to another, a considerable set-up time is incurred based on the number of component feeders to be replaced in the component magazine of the assembly machines. To support the order-mix decision faced by a major electronics manufacturer, two versions of a linear programming model are developed. The models differ primarily in their degree of aggregation and their computational effort. In order to reduce the aggregational error incurred, a fuzzy approach is developed to estimate the number of component set-ups at automatic SMD placement machines. Our numerical investigation reveals that sufficiently accurate solutions may be obtained from a highly aggregate fuzzy LP-model and this is achieved with considerably less computational effort than with a more detailed LP-model. We also demonstrate the potential suitability of the fuzzy LP-model for implementation within an interactive decision support system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545517
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  • 4
    Electronic Resource
    Electronic Resource
    Fast and accurate reflectivity calculations for shaped core optical fibres (2000)
    Springer
    Optical and quantum electronics 32 (2000), S. 1245-1255 
    Details
    ISSN: 1572-817X
    Keywords: facet reflectivity ; optical fibres ; analysis ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A novel scalar (i.e. paraxial) free space radiation mode method is presented for calculating the normal incidence facet reflectivity of the main guided mode of a step-index optical fibre with generally shaped smooth core. Numerical results are presented and discussed for several cases of the Nth order super-elliptical core shape, including the circular, elliptical, rectangular-type and slab limiting cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007066020238
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  • 5
    Electronic Resource
    Electronic Resource
    Modelling of optical amplification in Er/Yb co-doped LiNbO3 waveguides (2000)
    Springer
    Optical and quantum electronics 32 (2000), S. 819-827 
    Details
    ISSN: 1572-817X
    Keywords: channel waveguide ; energy transfer ; Er/Yb ; lithium niobate ; modelling ; optical amplifier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The optical amplification of LiNbO3:Er3+/Yb3+ channel waveguides has been modelled in the small signal regime using the overlapping integrals method and the rate-equation formalism. It has been found that Yb3+ -sensitisation improves the pump efficiency at 980 nm and a higher gain is achievable in the high power-limit compared to singly-doped LiNbO3:Er3+ amplifiers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007066529097
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  • 6
    Electronic Resource
    Electronic Resource
    A New Approach for the Modelling of Sediment Reworking Induced by a Macrobenthic Community (1997)
    Springer
    Acta biotheoretica 45 (1997), S. 295-319 
    Details
    ISSN: 1572-8358
    Keywords: bioturbation ; modelling ; macrobenthic ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new model of bioturbation has been developed to describe short term sediment reworking induced by macrobenthic communities. The design of the model had to consider the mixing processes, firstly, at the organism level, and secondly, at community level. This paper describes the mixing mode of the four types of bioturbators defined by the authors: the biodiffusors, the upward-conveyors, the downward-conveyors and the regenerators. The mathematical formulation of these sub-models consists of ordinary differential equations. They take into account the size of the bioturbated zone, the output fluxes to the water column, tracer decay, physical mixing due to local currents and the type and intensity of the bioturbation processes. These sub-models make it possible to describe correctly the mixing events that have occurred in cores with each type of bioturbator. They also provide the basis for general bioturbation model, that will take into account the respective degrees of involvement of (i) the different bioturbation processes and their characteristics, (ii) the interference between the different processes, and (iii) make possible to predict the particle reworking in order to include it in studies of organic matter in early diagenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000636109604
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  • 7
    Electronic Resource
    Electronic Resource
    The apple sawfly, Hoplocampa testudinea: a temperature driven model for spring emergence of adults (1996)
    Springer
    Entomologia experimentalis et applicata 78 (1996), S. 301-307 
    Details
    ISSN: 1570-7458
    Keywords: Apple sawfly ; Hoplocampa testudinea ; phenology ; post-diapause development ; sex ratio ; mortality temperature ; thermal threshold ; modelling ; Hymenoptera ; Tenthredinidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature on post-diapause development of the apple sawfly Hoplocampa testudinea Klug was studied under controlled conditions. Survival was found to decrease at temperatures higher than 15°C, the lethal temperature being close to 25°C. The lower thermal threshold was 4.5°C; the values for males and females did not differ significantly. However, different values were established for unprotected individuals, in vermiculite and in potting compost respectively. Based on the overall mean and variance of the developmental time and the overall thermal threshold a simple soil temperature driven phenology model was constructed using a time- varying distributed delay. The validation with independent field and semi-field data revealed the model to be a reliable tool to predict apple sawfly phenology and hence to determine the optimal time for the installation of white sticky traps or for control measures such as insecticide treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193449
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  • 8
    Electronic Resource
    Electronic Resource
    Intelligent modelling and optimization of the gas tungsten arc welding process (1999)
    Springer
    Journal of intelligent manufacturing 10 (1999), S. 73-79 
    Details
    ISSN: 1572-8145
    Keywords: Counter-propagation ; modelling ; simulated annealing ; optimization ; gas tungsten arc welding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper describes an application of neural networks and simulated annealing (SA) algorithm to model and optimize the gas tungsten arc welding (GTAW) process. The relationships between welding process parameters and weld pool features are established based on neural networks. In this study, the counter-propagation network (CPN) is selected to model the GTAW process due to the CPN equipped with good learning ability. An SA optimization algorithm is then applied to the CPN for searching for the welding process parameters with optimal weld pool features. Experimental results have shown that GTAW performance can be enhanced by using this approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008920631259
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  • 9
    Electronic Resource
    Electronic Resource
    Computer-assisted manufacturing process optimization with neural networks (1998)
    Springer
    Journal of intelligent manufacturing 9 (1998), S. 289-294 
    Details
    ISSN: 1572-8145
    Keywords: Manufacturing process chain ; modelling ; optimization ; neural networks ; evolutionary algorithms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Today's manufacturing methods are caught between the growing need for quality, high process safety, minimal manufacturing costs, and short manufacturing times. In order to meet these demands, process setting parameters have to be chosen in the best possible way, according to demand on quality. For such optimization it is necessary to represent the processes in a model. Due to the enormous complexity of many processes and the high number of influencing parameters, however, conventional approaches to modelling and optimization are no longer sufficient. In this article it is shown how, by means of applying neural networks for process modelling, even these highly complex interdependencies can be learned. That way both process and quality parameters can be assessed before or during processing. By connecting them with corresponding cost models, it is possible to optimize processes with the help of evolutionary algorithms. Using examples of different manufacturing processes, the possi bilities for process modelling and optimization with neural networks and evolutionary algorithms are demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008966407212
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  • 10
    Electronic Resource
    Electronic Resource
    Developing a quantitative intelligent system for implementing concurrent engineering design (1994)
    Springer
    Journal of intelligent manufacturing 5 (1994), S. 251-267 
    Details
    ISSN: 1572-8145
    Keywords: Concurrent engineering design ; knowledge reasoning ; optimization ; feature ; modelling ; design function ; production costs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This research focuses on the development of a quantitative intelligent system for implementing concurrent engineering design. The paper first discusses the task of concurrent engineering design and the basic requirements for conducting integrated concurrent engineering design. The proposed quantitative intelligent system approach combines qualitative reasoning, based upon design and manufacturing knowledge, and quantitative evaluation and optimization, conducted using design information and manufacturing data generated in the knowledge-based reasoning. The method allows considerations on non-operating principle aspects of a product to be incorporated into the design phase, such as manufacturing, maintenance, service, recycle, etc., with an emphasis on production costs. The proposed method serves as a convenient software tool for gathering information required in the concurrent engineering design process and integrates tasks from different parts of the product development life cycle, particularly function design, manufacturability analysis and production cost estimation. A prototype software system is developed based upon this method using Smalltalk-80. In the prototype system, concurrent engineering design is carried out by: (1) describing and representing design requirements; (2) generating feasible design candidates and evaluating their design functions; (3) representing design geometry; (4) finding the associated production processes and predicting the production costs of each feasible design; and (5) identifying the costeffective design that satisfies given design requirements and requires minimum production costs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123697
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