1,721,301 research outputs found
Class fields from the fundamental Thompson series of level N = o(g)
No full textThompson series is a Hauptmodul for a genus zero group which lies between Gamma(0)(N) and its normalizer in PSL2(R) ([1]). We construct explicit ring class fields over an imaginary quadratic field K from the Thompson series T-g(alpha) (Theorem 4), which would be an extension of [3], Theorem 3.7.5 (2) by using the Shimura theory and the standard results of complex multiplication. Also we construct various class fields over K, over a CM-field K(zeta(N) + zeta(N)(-1)), and over a field K(zeta N). Furthermore, we find an explicit formula for the conjugates of T-g (alpha) to calculate its minimal polynomial where alpha(is an element of h) is the quotient of a basis of an integral ideal in K
Formation of e-satisfaction and repurchase intention: Moderating roles of computer self-efficacy and computer anxiety
No full textThe exploration of online customer satisfaction (called e-satisfaction hereafter) and repurchase becomes increasingly important in e-commerce. Yet, the process of e-satisfaction and repurchase formation and the context under which this process may vary have not been investigated rigorously. In order to fill this knowledge gap, this paper attempts to develop a conceptual model to decipher how e-satisfaction is formed. Furthermore, it investigates how computer-related individual differences such as computer self-efficacy and computer anxiety moderate this formation. The analysis results from a survey of 274 online buyers confirm that our antecedents play key roles in forming e-satisfaction and repurchase and the proposed moderators are important. (C) 2008 Elsevier Ltd. All rights reserved
Sintering kinetics by structural transition at grain boundaries in barium titanate
No full textFor its analysis and understanding, sintering has been conventionally assumed to occur in proportion to driving force [J. Appl. Phys. 36 (1955) 1205; Acta Metall. 13 (1965) 227; Mater. Sci. Eng. 48 (1981) 53; Ceramic Processing and Sintering, Marcel Dekker, New York, 2003, p. 470]. This investigation, however, shows for the first time that the conventional assumption does not apply to faceted boundaries and that the microstructure can be frozen for faceted boundaries. A structural transition from rough to faceted was induced in BaTiO(3), by changing oxygen partial pressure. As long as the boundary was rough, continuous grain growth and densification occurred with sintering time, in agreement with the conventional assumption. With the onset of the structural transition from rough to faceted, however, grain growth and densification rates were reduced and became zero at the completion of the transition. This result demonstrates that critical driving forces are present for grain growth and densification for faceted boundaries, unlike the conventional understanding. The result also suggests that the formation or maintenance of faceted boundaries is crucial to inhibit grain growth and thus to produce ultrafine-structured materials. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
A spatial scheduling system and its application to shipbuilding: DAS-CURVE
No full textSpatial scheduling considers not only traditional scheduling constraints like resource capacity and due dates, but also dynamic spatial layout of the objects. Automation of spatial scheduling is particularly important when the spatial resources are critical bottleneck resources, as is the case in the shipbuilding industry. To develop a spatial scheduling expert system for shipbuilding, a methodology for spatial layout of polygonal objects within rectangular plates is first developed. This study is then extended to the methodology for spatial scheduling, including the lime dimension. The methodology is applied to the scheduling of Daewoo shipbuilding to build a system DAS-CURVE. DAS-CURVE is successfully operational and its experimental performance is remarkable. Copyright (C) 1996 Elsevier Science Lt
The effects of socio-technical enablers on knowledge sharing: an exploratory examination
No full textRecently, the need for knowledge management has been drastically increasing so organizations may meet the high level of dynamic, complex business change and uncertainty. In particular, knowledge sharing has been recognized as a critical process through which organizational knowledge can be utilized. For successful knowledge sharing, companies need to capitalize on various socio- technical enablers. The primary objective of this paper is to provide a better understanding of how these enablers can affect knowledge sharing intention and behavior, and explore practical implications for knowledge sharing. For this purpose, the paper proposes a theoretical model to investigate these enablers from a socio-technical perspective. PLS (Partial Least Square) analysis was employed to validate the model. This field study involves 164 users. Furthermore, interviews with experts were investigated for practical implications. Our analysis reveals that social enablers such as trust and reward mechanisms are more important than technical support in isolation for facilitating knowledge sharing.
Kinetic formation and thickening of intergranular amorphous films at grain boundaries in barium titanate
No full textKinetic formation and distribution of amorphous films at grain boundaries during grain growth have been studied in a model ceramic system, BaTiO(3), using single crystal/polycrystal bi-layers. Single crystal containing BaTiO(3) powder compacts with different TiO(2) additions (0.1: 0.4 and 1.0 mol%) were heat-treated at 1250 degreesC for 10 h in H(2) and then annealed at 1350 degreesC, above the eutectic temperature, in air for up to 50 h. During the air-annealing the single crystals grew into fine matrix grains of similar to2.0 mum diameter while no grain growth occurred in the matrix. With the growth of the single crystal, an amorphous film formed at the boundaries between the crystal and the matrix grains, and its thickness increased. As the amount of TiO(2) increased from 0.1 to 1.0 mol%, the film thickness increased about ten times. These experimental results show for the first time that: (i) grain growth in solid-liquid two phase materials can induce the formation and thickening of intergranular amorphous films at dry grain boundaries, and (ii) the film thickening is mainly due to the penetration of liquid pockets at triple junctions into the films formed during grain growth. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Grain-growth behavior during stepwise sintering of barium titanate in hydrogen gas and air
No full textTo study the effect of oxygen partial pressure on grain growth in BaTiO3, TiO2-excess samples have been sintered in air with and without a prior H-2 heat treatment. Without prior H-2 treatment, abnormal grain growth occurs below and above the eutectic temperature (T-e). An introduction of H, treatment before air sintering, however, increases the average grain size and suppresses the formation of abnormal grains during subsequent air sintering below and above T-e. This H-2 treatment effect has been explained in terms of a decrease of the driving force for the growth of faceted grains below a critical value for formation of abnormal grains. The observed grain-growth behavior under various atmospheres demonstrates the possibility of having various microstructures via control of oxygen partial pressure and initial grain size
Abnormal grain growth in barium titanate doped with alumina
No full textThe effect of additions of <= 1 mol% Al2O3 on abnormal grain growth in BaTiO3 sintered for periods of <= 60 min at 1350 degrees C has been studied. Addition of <= 0.2 mol% Al2O3 caused an increase in the nucleation and growth rates of abnormal grains, with further additions causing a decrease. This behavior is explained by interface-controlled growth. Dopant adsorption reduces both the edge free energy and the step velocity of a grain, causing the nucleation and growth rates of abnormal grains to increase, pass through a maximum, and then decrease with increasing dopant concentration
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