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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4248-4254 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The early stage of electromigration in thin gold films on polyimide has been investigated at room temperature using the resistometric technique. While the resistance increase is initially linear, a saturation tendency is observed for longer stressing times at all stress current densities. A simple model is described which relates the saturation behavior in the resistance change to the buildup of mechanical stress gradients, which produce a counterflux of metal ions proportional to the stress gradient. The stress gradients arise due to nonuniformity in the grain size in the polycrystalline thin metal films which produces cluster regions of small grain size alternating with regions of large or near-bamboo grain size, which have larger and smaller metal ion diffusivities, respectively. The dependence of the maximum level of the resistance's change and the rate of resistance increase on the stress current density are experimentally characterized and compared with the model's predictions with good agreement. © 1998 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 9326-9333 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The in-plane optical loss was correlated with molecular orientation in a unidirectionally stretched poly(ethylene terephthalate-co-isophthalate) copolyester film. X-ray scattering was applied to ascertain the anisotropic and amorphous natures of the stretched film. The film was adhered onto a silicon wafer to fabricate a planar waveguide. Multiple TE and TM propagation modes were obtained on the planar waveguide using a prism coupler at 632.8 nm yielding in-plane refractive indices of 1.6545 and 1.5464, parallel and transverse to the stretch direction, respectively. For each waveguide mode, a propagation streak was generated and registered on photographic film. The in-plane linear attenuation coefficient, α(parallel)≡{ln[I(O)/I(x(parallel))]}/x(parallel), was derived from the propagation streak. The optical path of each mode was determined and used to normalize α(parallel). For the TE modes, α(parallel) increased with the mode number and was highly anisotropic, i.e., α(parallel) (parallel to the stretch direction)≤α(parallel) (transverse to the stretch direction). However, for the TM modes, α(parallel) was found to be a constant smaller than those of the TE modes, and was independent of mode number as well as molecular orientation. The bulk α(parallel) was extrapolated to remove the surface loss contributions for the planar waveguide. Dipole interaction between the stretched copolyester, surface irregularities, and the TE or TM polarization was analyzed to delineate the in-plane optical loss behavior. © 1996 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2550-2552 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of the sidegate voltage on the Schottky barrier in the ion-implanted active layer via the Schottky pad on the semi-insulating GaAs substrate was observed, and the mechanism for such an influence was proposed. © 1996 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 280-286 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Oxidatively stable and electrically insulating rigid-rod polymer poly(p-phenylenebenzobisthiazole) (PBT), was incorporated with electroactive triarylamino (TPA) moieties, (R)TPA-PBT with R=NMe2 and Me. Copolymers or homopolymers were synthesized with various TPA fractions changing the polymers to segmentally rigid configuration, and fabricated into films. On cast films, x-ray scattering revealed that the copolymers were random copolymers, microscopy showed "template effect" from the rigid segments. Iodine activation of the incorporated polymers led consistently to more than five order-of-magnitude increases in electrical conductivity. The activated conductivity also increased with TPA fraction. A conductivity value as high as 4.1×10−4 S/cm was realized for the activated (NMe2)TPA-PBT homopolymer. However, temporal stabilities were observed for the conductivity, which seemed to depend on the polymer composition and film morphology. Spectroscopic examination detected no new electronic state generated by iodine doping. Instead, optical absorbance was drastically increased for hν greater than 2 eV with a change in film color. Both enhanced conductivity and absorbance were not exhibited by the iodine-activated PBT polymer. © 1999 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 28 (1997), S. 0 
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Two consecutive 6-week feeding trials were conducted to determine the amount of haemoglobin powder (BM) that could replace fish meal (FM) in juvenile Japanese eel Anguilla japonica (Temminck et Schlegel) diets. Fish were fed 50% crude protein diets in which each of ten isonitrogenous diets was formulated to contain white fish meal and/or blood meal as the dietary protein source to replace FM by BM as follows: Diet 1 (control), 0% BM; diet 2,12.5% BM; diet 3,25% BM; diet 4, 50% BM; diet 5, 75% BM; diet6,100%BM;diet7,25%BM + 3 Essential Amino Acids (EAA); diet 8, 50% BM + 3 EAA; diet 9, 75% BM + 3 EAA; diet 10, 100 BM + 3 EAA. In the first 6-week period, the results were not consistent with the treatments, and poor adaptation of the fish to the experimental diets and conditions was observed. In the second 6-week period, weight gain, specific growth rate, protein efficiency ratio and protein productive value offish fed diets 2, 3, 4, 7, 8 and 9 were not significantly different from those of fish fed the control diet (P 〉 0.05). However, feed conversion ratios offish fed diets 6 and 10 were lower than that offish fed the control diet (P 〈 0.05). These results demonstrate that FM can be replaced by BM up to 50% without supplementation of three EAA, and up to 75% with three EAA supplementation in juvenile Japanese eel diets.
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  • 6
    ISSN: 1436-6304
    Keywords: Production scheduling ; dynamic setup change ; Produktionsablaufplanung ; stochastisches Flow-Shop-Problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung Wir betrachten ein zweistufiges Produktionssystem, in dem zwei Produkte mit konstanten produktspezifischen Produktionsgeschwindigkeiten und Rüstzeiten bearbeitet werden. Zwischen den beiden Maschinen sind zwei produktspezifische Puffer angeordnet. Die Nachfragerate für jedes Produkt ist abschnittsweise konstant. Jede Maschine unterliegt zeitabhängigen Störungen. Die fehlerfreien Laufzeiten und die Reparaturzeiten sind exponentialverteilte Zufallsvariablen, wobei Rüst- und Bearbeitungsvorgänge nach einer störungsbedingten Unterbrechung ohne Verlust fortgesetzt werden. Wir modellieren das Produktionssystem als zeit- und mengenkontinuierlichen Prozeß. Es wird das Problem der Bestimmung der optimalen Kontrollpolitik mit dem Ziel der Minimierung der diskontierten Kosten bei unendlichem Horizont formuliert. Zur Bestimmung der Struktur der optimalen Kontrollpolitik wird eine diskretisierte Version des Problems mit Hilfe der dynamischen Programmierung unter Berücksichtigung einer stückweise linearen Strafkostenfunktion gelöst. Anschließend wird ein Algorithmus entwickelt, mit dem geringe Lagerbestände bei gleichzeitiger Erfüllung der Nachfrage erreicht werden können. Der Algorithmus, der auf einer hierarchischen Kontrollstruktur basiert, dient zur Bestimmung der Produktionszeitpunkte, wobei in Echtzeit auf zufällige Störungen im System reagiert werden kann. Die Leistungsfähigkeit des Verfahrens wird anhand eines Simulationsmodells mit alternativen Politiken verglichen.
    Notes: Abstract In this paper, we study a manufacturing system consisting of two machines separated by two intermediate buffers, and capable of producing two different products. Each product requires a constant processing time on each of the machines. Each machine requires a constant non-negligible setup change time from one product to the other. The demand rate for each product is considered to be piecewise constant. Each machine undergoes failure and repair. The time-to-failure and time-to-repair are exponentially distributed random variables. The setup change and processing operations are resumable. We model our system as a continuous time, continuous flow process. An optimal control problem is formulated for the system to minimize the total expected discounted cost over an infinite horizon. To determine the optimal control policy structure, a discrete version of the problem is solved numerically using a dynamic programming formulation with a piecewise linear penalty function. A real-time control algorithm is then developed with the objective of maintaining low work-in-process inventory and keeping the production close to the demand. The algorithm uses a hierarchical control structure to generate the loading times for each product on each machine in real time and to respond to random disruptions in the system. The system is simulated using this algorithm to study its performance. The performance of the algorithm is also compared to alternative policies.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    OR spectrum 18 (1996), S. 187-195 
    ISSN: 1436-6304
    Keywords: Stochastic production scheduling ; work-in-process inventory control ; Stochastische Maschinenbelegungsplanung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung In diesem Beitrag wird ein hierarchischer Planungsansatz zur Steuerung eines Produktionssystems mitN Maschinen betrachtet. Für jede von vielen herzustellenden Produktarten ist die Maschinenfolge durch den jeweiligen Produktionsprozeß fest vorgegeben. Gegebenenfalls sind Maschinen mehrmals zu durchlaufen. Außerdem sind zufällige Maschinenausfälle und Reparaturzeiten zu beachten. Solche Systeme treten z.B. bei der Halbleiterfertigung auf. Ziel der Planung ist eine möglichst bedarfssynchrone Produktion bei niedrigen Lagerbeständen an Halbfertigfabrikaten und hohen Produktionsraten. In der obersten Ebene einer dreistufigen Planungshierarchie werden im Rahmen einer Kapazitätsplanung wünschenswerte Puffergrößen und Produktionsraten der Maschinen ermittelt. In der mittleren Ebene erfolgt eine Anpassung der Produktionsraten, um Störungen des Systems durch Maschinenausfälle oder Blockierung von Maschinen zu beseitigen. In der untersten Planungsebene wird eine Durchlaufterminierung vorgenommen. Eine Simulationsuntersuchung zeigt, daß der vorgeschlagene Planungsansatz gute Ergebnisse liefert.
    Notes: Abstract In this paper, we propose a procedure for production flow control in reentrant manufacturing systems. The system under study consists ofN machines and producesM product types simultaneously. Each part goes through the system following a predefined process and may visit a machine many times. All machines are subject to random failures and need random repair times. The scheduling objectives are to keep the production close to demand and to keep the WIP inventory level and cycle times at low values. The model is motivated by semiconductor fabrication production. A three-level hierarchical controller is constructed to regulate the production. At the top level of this hierarchy, we perform capacity planning by selecting the desirable buffer sizes and the target production level for each operation. A production flow rate controller is at the middle level which recalculates the production rates whenever a machine fails or is starved or blocked. The loading times for individual parts are determined at the bottom level of the hierarchy. Comparison with alternative control is made through simulation and it shows that the control policy performs well.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 17 (1998), S. 1805-1807 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2925-2933 
    ISSN: 0887-6266
    Keywords: ionic conductivity ; DC conductivity ; rigid-rod polymer ; depletion measurement ; X-ray scattering ; anisotropic ; polymer electrolyte ; polyelectrolyte ; conducting polymers ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conductivity study results of lithium-doped sulfonated PBI, a conjugated rigid rod polymer, poly[(1,7-dihydrobenzo[1,2-d:4,5-d′]dimidazole-2,6-diyl)-2-(2-sulfo)-p-phenylene], derivatized with pendants of propane sulfonate Li+ ionomer are reported. The room-temperature DC four-probe conductivity parallel to the surface of cast films was as large as 8.3 × 10-3 S/cm. Similar measurements with an eight-probe configuration showed no difference between bulk and surface conductivity. The ionic nature of the conductivity was indicated by constant voltage depletion experiments and by secondary ion mass spectroscopy measurements of the residues near the electrodes. The DC two-probe conductivity measured transverse to the sample surface was three to four orders of magnitude smaller than longitudinal conductivity, while the AC two-probe conductivity was even less. Electron microscopy indicated that the films had a layered structure parallel to the surfaces. This structural anisotropy was confirmed by refractive index values obtained from wave-guide experiments and by wide angle X-ray scattering. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2925-2933, 1997
    Additional Material: 11 Ill.
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  • 10
    Publication Date: 1999-09-01
    Print ISSN: 0888-5885
    Electronic ISSN: 1520-5045
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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