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排序方式: 共有240条查询结果,搜索用时 8 毫秒
41.
Dominic Phelan Mark Reid Nicole Stanford Rian Dippenaar 《JOM Journal of the Minerals, Metals and Materials Society》2006,58(9):67-69
An in-situ laser-scanning confocal microscopy study has been undertaken on the phase transformations in highpurity titanium. Observations of the β-Ti to α-Ti were observed to proceed with a pronounced Widmanstätten plate morphology due to the large β-Ti grain size. An anomalous transformation was also observed, with the α-Ti growing with a defined ledge-like surface relief. The observed transformation morphologies are discussed with reference to the crystallography of the regions, analyzed using electron-backscatter diffraction. 相似文献
42.
Roelofs Jeffrey; Braet Caroline; Rood Lea; Timbremont Benedikte; van Vlierberghe Leen; Goossens Lien; van Breukelen Gerard 《Canadian Metallurgical Quarterly》2010,22(4):866
This study aimed to (a) assess relationships between the Children's Depression Inventory (CDI) and DSM-oriented depression and anxiety scales of the Youth Self Report, (b) develop reliable norms for the CDI, and (c) determine CDI cutoff scores for selecting youngsters at risk for depression and anxiety. A total of 3,073 nonclinical and 511 clinically referred children and adolescents from The Netherlands and Belgium were included. Results showed that CDI scores were significantly related to DSM-oriented symptoms of both depression and anxiety. CDI scores correlated highly with depression symptoms and moderately with anxiety symptoms. Norms for the CDI were determined by means of multiple regression analysis and depended on sex, age, and country. CDI cutoff scores for selecting individuals at risk for depression and anxiety as measured by the DSM-oriented depression and anxiety scales of the Youth Self Report were determined by means of multiple regression analysis and receiver operating characteristic analysis. A CDI score of 16 was found to have the most optimal balance between sensitivity and specificity for depression, whereas a score of 21 provided the best sensitivity and specificity for anxiety in a subsample of children. We conclude that the CDI is an effective instrument for screening depression and to a lesser extent anxiety in primary and secondary care centers, before applying further assessment of high-risk individuals. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
43.
Kun Yan Dave G. Carr Saurabh Kabra Mark Reid Andrew Studer Robert P. Harrison Rian Dippenaar Klaus‐Dieter Liss 《Advanced Engineering Materials》2011,13(9):882-886
The α–β phase transformation behavior of Zr‐2.5Nb (in mass%) has been characterized in real time during an in situ neutron diffraction experiment. The Zr‐2.5Nb material in the current study consists, at room temperature, of α‐Zr phase (hcp) and two β phases (bcc), a Nb rich β‐Nb phase and retained, Zr rich, β‐Zr(Nb) phase. It is suggested that this is related to a quench off the equilibrium solubility of Nb atoms in the Zr bcc unit cells. Vegard's law combined with thermal expansion is applied to calculate the composition of the β‐phase, which is compared with the phase diagram, revealing the system's kinetic behavior for approaching equilibrium. 相似文献
44.
W. S. Christian Roelofs Willem H. Adriaans René A. J. Janssen Martijn Kemerink Dago M. de Leeuw 《Advanced functional materials》2013,23(33):4133-4139
Light emission from ambipolar organic field‐effect transistors (OFETs) is often observed when they are operated in the unipolar regime. This is unexpected, the light emission should be completely suppressed, because in the unipolar regime only one type of charge carrier is accumulated. Here, an electroluminescent diketopyrrolopyrrole copolymer is investigated. Local potential measurements by scanning Kelvin probe microscopy reveal a recombination position that is unstable in time due to the presence of injection barriers. The electroluminescence and electrical transport have been numerically analyzed. It is shown that the counterintuitive unipolar light emission is quantitatively explained by injection of minority carriers into deep tail states of the semiconductor. The density of the injected minority carriers is small. Hence they are relatively immobile and they recombine close the contact with accumulated majority carriers. The unipolar light output is characterized by a constant efficiency independent of gate bias. It is argued that light emission from OFETs predominantly originates from the unipolar regime when the charge transport is injection limited. 相似文献
45.
T. Schmitz S. Tiedke K. Prume A. Roelofs K. Szot R. Waser 《Integrated ferroelectrics》2013,141(1):371-378
Ferroelectric capacitors of submicron size for nonvolatile memory applications are entering the structure size of nanotechnology. Therefore the signal level for hysteresis measurements is getting much smaller than the influence of the parasitic capacitance of the measurement setup, e.g. caused by the cantilever of a scanning force microscope (SFM) used for contacting. A novel compensation method significantly increases the signal to noise ratio by active cancellation of the parasitic capacitance of the setup during the measurement. 相似文献
46.
Rian Van Staden 《Refocus》2001,2(8):45
The International Solar Energy Society has been experiencing an extraordinary period of change of late, in this article, Rian Van Staden, new Executive Director of ISES highlights current developments and initiatives at the organisation. 相似文献
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J. C. Roelofs 《Behaviour & Information Technology》1987,6(4):403-410
The aim of this study was to determine the degree of acceptance of synthetic speech in a practical application and to clarify some of the factors which are important for its acceptance. Synthetic speech was used in two simulated telephone services. The availability of interrrupt facilities, the speaking rate and service type were varied. The performance (success in writing down the requested data) and some subjective reactions were recorded. Performance was worse with synthetic speech in comparison with normal speech. Neither the interrupt facilities nor the speaking rate had any influence on performance. The interrupt facilities were appreciated, although they were hardly used. Having the possibility of interrupting the synthetic speech caused the subjects to judge the system as more flexible and to rate the experienced tempo as slower. The answers on the questions about acceptance suggested a positive effect of the interrupt variable, but this was not significant. Suggestions concerning the use of synthetic speech are given. 相似文献