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  • Springer  (304)
  • Oxford University Press  (53)
  • 1995-1999  (253)
  • 1975-1979  (104)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 58 (1996), S. 1047-1074 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We develop a macroscopic model for delivering drug to brain tumors. The model accounts for bulk convective and diffusive transport across the blood-brain barrier and through the interstitial space. Through mathematical analysis and simulations, we assess the effects of changing parameters (within physiological bounds) on drug delivery. We find that there is an optimal treatment for convective drug delivery to the center of the tumor. We interpret this phenomenon in terms of traffic flow. The implications of our analyses on existing chemotherapeutic protocols are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We present a model for the formation of parallel rows of scale cells in the developing adult wing of moths and butterflies. Precursors of scale cells differentiate throughout each epithelial monolayer and migrate into rows that are roughly parallel to the body axis. Grafting experiments have revealed what appears to be a gradient of adhesivity along the wing. What is more, cell adhesivity character is maintained after grafting. Thus we suggest that it is a cell’s location prior to migration that determines its interactions during migration. We use nonlinear bifurcation analysis to show that differential origin-dependent cell adhesion can result in the stabilization of rows over spots.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    OR spectrum 17 (1995), S. 99-111 
    ISSN: 1436-6304
    Keywords: Robot acquisition planning ; equipment selection ; mathematical programming ; heuristic search ; tabu search ; simulated annealing ; Roboter Anschaffungsplanung ; CIM ; Bin packing ; Tabu search ; Simulated annealing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung Dieser Bericht beschreibt die Entwicklung eines mathematischen Programms und dreier effizienter Entscheidungsregeln für die Anschaffungsplanung von Robotern verschiedener Typen für ein CIM-System. In unserem Modell wird eine Kombination von Robotern verschiedener Typen zusammengestellt, die den operationalen Anforderungen (d.h. Zeit und Raum) einer bestimmten Anzahl von Arbeitsplätzen bei gleichzeitig minimalem Kostenaufwand gerecht wird. Im Detail bedeutet das: jeder Roboter zeichnet sich einerseits durch seinen festgesetzten Preis aus und andererseits unterliegt er zwei Kapazitätsbeschränkungen: seiner Maschinenzeit und seiner Arbeitsfläche; jeder Arbeitsplatz stellt bestimmte Anforderungen, die uns bekannt sind, sowohl an die Maschinenzeit als auch an die Arbeitsfläche und soll von nur einem Roboter bedient werden. Das Modell wird durch ein mathematisches 0–1-Programm dargestellt und hat sich als schwieriger als das bekannte NP-schwere zweidimensionale Bin Packing-Problem herausgestellt. Die drei entwickelten Entscheidungsregeln sind: ‘greedy heuristic’, ‘tabu thresholding’ und ‘simulated annealing’. Alle Entscheidungsregeln wurden anhand 450 zufällig generierter Problemfälle getestet. Die Computerergebnisse deuten darauf hin, daß alle Algorithmen für die Lösung von Problemen praktischer Größen (d.h. 50 Arbeitsplätze und maximal 20 Roboter) anwendbar und ausreichend sind. Hinsichtlich der zeitlichen Dauer und Qualität der Problemlösung hebt sich jedoch keine der Entscheidungsregeln wesentlich von den anderen beiden ab. Zukünftige Forschungsaspekte werden ebenfalls aufgeführt.
    Notes: Abstract In this paper, a planning model and three efficient heuristics are developed for equipment acquisition planning for a CIM system using multiple-type robots. Our planning model considers selection of a proper mix of multiple-type robots such that operational requirements (i.e., time and space) from a given number of work stations are satisfied at minimal system cost. In specific, each robot is characterized by its fixed charge and subject to two capacity constraints on machine time and work space; and each work station has known demands for both machine time and work space, and is to be served by only one robot. The model is formulated as a pure 0–1 mathematical program and is shown to be harder than two-dimensional bin packing, a well-known NP-hard problem. The three heuristics developed are: a greedy heuristic, tabu thresholding, and simulated annealing. All heuristics are tested by solving 450 randomly generated problems. Computational results indicate that all three heuristics are effective and efficient in solving problems of a practical size (i.e., 50 work stations and a maximum of 20 robots). However, none of the heuristics are overwhelmingly better than the others in terms of both solution time and quality. Future research issues are also discussed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 10 (1978), S. 179-180 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Agriculture and human values 16 (1999), S. 141-150 
    ISSN: 1572-8366
    Keywords: Community food security ; Hunger ; Food security ; Food systems ; Planning ; Theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Practitioners and advocates of community food security (CFS) envision food systems that are decentralized, environmentally-sound over a long time-frame, supportive of collective rather than only individual needs, effective in assuring equitable food access, and created by democratic decision-making. These themes are loosely connected in literature about CFS, with no logical linkages among them. Clear articulation in a theoretical framework is needed for CFS to be effective as a guide for policy and action. CFS theory should delimit the level of analysis (i.e., what are the boundaries of “community”); show how CFS relates to individual, household, and national food security and explain emergent properties, which are important at the community level of analysis; point to the best indicators of CFS or its lack; clarify the determinants of CFS; and clarify the stages of movement toward CFS. This theoretical base would allow researchers to develop valid and reliable measures, and allow practitioners to weigh alternative options to create strategic plans. A theoretical base also would help establish common ground with potential partners by making the connections to anti-hunger work, sustainable agriculture, and community development clear.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent manufacturing 9 (1998), S. 413-430 
    ISSN: 1572-8145
    Keywords: Manufacturing control ; discrete-event systems ; artificial intelligence ; machine planning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper*, we provide tools for integrating machine planning and manufacturing. Specifically, we show how assembly trees can be coded into operators for machine planners and how machine planners can represent flow-lines, assembly and job-shop choices. We provide a polynomial-time algorithm for succinctly combining multiple plans; the resulting plan can be expressed as four matrices that are equivalent to a Petri net. We also provide a dynamic supervisory controller that can execute a single plan or switch between multiple plans as real-time conditions change.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-8145
    Keywords: Radial basis function network ; kernel function ; conscience function ; generalized delta rule ; time series forecasting ; response surface methodology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A radial basis function (RBF) neural network was designed for time series forecasting using both an adaptive learning algorithm and response surface methodology (RSM). To improve the traditional RBF network‘s forecasting capability, the generalized delta rule learning method was employed to modify the radius of the kernel function. Then RSM was utilized to explore the mean square error response surface so that the appropriate combination of network parameters, such as the number of hidden nodes and the initial learning rates, could be found. Extensive studies were performed on the effect of the initial values of connection weights on the accuracy of the backpropagation learning method that was employed in the training of the RBF artificial neural network. The effectiveness of the neural network with the proposed radius-modification technique and the RSM method was demonstrated with an example of forecasting intensity pulsations of a laser. It was found that, by utilizing the proposed techniques, the neural network provided a more accurate prediction of the response.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 8 (1978), S. 253-263 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A form of alkaline creepage, other than that governed by electrocapillary phenomena, has been studied on partially immersed negatively polarized electrodes. This extra-creepage is believed to result from concentration gradients generated in the thin spreading film above the intrinsic liquid meniscus by the electrochemical reduction of oxygen and/or water. Consequent transport of water into the spreading film allows it to expand and advance further along the electrode.
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  • 9
    ISSN: 1572-8854
    Keywords: Isomeric oximes ; X-ray diffraction ; heterocyclic isomer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of two isomeric oximes, C11N10N2OS have been studied by X-ray diffraction. The open-chain thiocyanato derivative is somewhat'less dense and crystallizes with the orthorhombic space group Pbcn;a,b,c=18.718(1), 10.601(3), 11.528(1) Å,Z=8. The heterocyclic isomer occurs as pseudo-orthorhombic (Cmma)twinned crystals of space group P21/n, a, b, c, β=12.11(1), 7.46(1), 12.12(1) Å, 100.09(1)o,Z=4. Twinning occurs as a result of the near-equality of the monoclinica andc cell constants.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of insect behavior 12 (1999), S. 767-779 
    ISSN: 1572-8889
    Keywords: fecundity ; longevity ; multiple mating ; sperm competition ; paternal investment, apyrene, eupyrene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I investigated two possible reasons for remating in female Plodia interpunctella: i) females remate to obtain sufficient sperm to maintain fertility; and ii) male investment in non-sperm components increases female fecundity and longevity. The number of sperm and the mass of the spermatophore transferred by males decreases on successive matings. Sperm numbers and potential male investment were varied by allowing females to mate either once or twice with males either on their first or second mating. Females receiving a single small spermatophore containing few sperm (from a male on his second mating) had sufficient sperm to fertilize all their eggs. Females did not show increased fecundity or longevity as a result of obtaining more spermatophore material. I discuss why females remate when they already have sufficient sperm to fertilize all their eggs.
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