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51.
52.
Sung D. Kwon Sung J. Song Dong H. Bae Young Z. Lee 《Journal of Mechanical Science and Technology》2002,16(9):1084-1092
The frequency dependency of Rayleigh surface wave is investigated indirectly by measuring the angular dependency of the backward
radiation of the incident ultrasonic wave in two kinds of degraded specimens by scuffing or corrosion. Then, the frequency
dependency is compared with the residual stress distribution or the corrosion-fatigue characteristics for the scuffed or corroded
specimens, respectively. The width of the backward radiation profile increases with the increase of the variation in residual
stress distribution for the scuffed specimens. In the corroded specimens, the profile width decreases with the increase of
the effective aging layer thickness and is inversely proportional to the exponent, m, in the Paris’ law that can predict the
crack size increase due to fatigue. The result observed in this study demonstrates high potential of backward radiated ultrasound
as a tool for nondestructive evaluation of subsurface gradient of material degradation generated by scuffing or corrosion. 相似文献
53.
Less may not be more,but it still counts: The state of social capital in Yeoville,Johannesburg 总被引:2,自引:2,他引:0
Kirsten Harrison 《Urban Forum》2002,13(1):67-84
54.
55.
Yanqiu Shao Jiqing Han Ting Liu Yongzhen Zhao 《International Journal of Speech Technology》2007,10(1):45-55
In real speech, not like lexical words (LWs), prosodic words (PWs) are basic rhythmic units. The naturalness of a Text-to-Speech
(TTS) system is directly influenced by the segmentation of the PWs. Most of the PWs are the combination of several LWs. In
this paper, three Lexical Combination Models are proposed to combine LWs into PWs, including a Directed Acyclic Graph Model,
a Segmentation Model and a Markov Model (MM). To cope with the situation where some long LWs should be segmented into two
or more PWs, a Lexical Split Model (LSM) is applied to the long LWs. Experimental results prove that relatively constant results
with various training data can be obtained from a MM. The Transformation-Based Error Driven Learning (TBED) algorithm, for
its high performance of individual property, is applied in combination with the MM to improve the precision of PW segmentation.
Experiments show that among the three proposed models, the MM combined with TBED and LSM, leads to the best performance, in
which a precision of 93.00% and a recall of 93.23% are achieved. The perception test indicates that by using PWs as the lowest
prosodic units a speech sounds more natural and acceptable than by using LWs.
This paper is supported by NSFC Project (60503071); 973 Natural Basic Research Program of China (2004CB318102); Postdoctor
Science Foundation of P. R. China (20070420275). 相似文献
56.
In this paper we describe, from a theoretical point of view, critical configurations for the projective reconstruction of
a set of points, for a single view, i.e. for calibration of a camera, in the case of projections from ℙk to ℙ2 for k ≥ 4. We give first a general result describing these critical loci in ℙk, which, if irreducible, are algebraic varieties of dimension k−2 and degree 3. If k=4 they can be either a smooth ruled surface or a cone and if k = 5 they can be a smooth three dimensional variety, ruled in planes, or a cone. If k≥ 6, the variety is always a cone, the
vertex of which has dimension at least k − 6. The reducible cases are studied in Appendix A.
These results are then applied to determine explicitly the critical loci for the projections from ℙk which arise from the dynamic scenes in ℙ3 considered in [13].
Marina Bertolini is currently Associate Professor of Geometry at the Department of Mathematics at the Università degli Studi di Milano, Italy.
Her main field of research is Complex Projective Algebraic Geometry, with particular interest for the classification of projective
varieties and for the geometry of Grassmann varieties. On these topics M. Bertolini has published more than twenty reviewed
papers on national and international journals. She has been for some years now interested also in applications of Algebraic
Geometry to Computer Vision problems.
Cristina Turrini is Associate Professor of Geometry at the Department of Mathematics of Università degli Studi di Milano, Italy. Her main
research interest is Complex Projective Algebraic Geometry: subvarieties of Grassmannians, special varieties, automorphisms,
classification. In the last two years she has started to work on applications of Algebraic Geometry to problems of Computer
Vision. She is author or co-author of about thirty reviewed papers. She is also involved in popularization of Mathematics,
and on this subject she is co-editor of some books. 相似文献
57.
啤酒酵母菌种用液体石蜡技术保藏具有设备简单、操作方便,成活率高,变异少,优良种性能保持较长时间的优点,实用价值高。本文从液体石蜡保藏菌种的机理、保藏效果、保藏等具体技术操作及其使用方法都作了较为详细的介绍,相信能为啤酒菌种的保藏带来较大的好处。 相似文献
58.
59.
Jon T. Carter Paul E. Krajewski Ravi Verma 《JOM Journal of the Minerals, Metals and Materials Society》2008,60(11):77-81
The hot blow forming of magnesium sheet offers significant opportunity for forming complex, lightweight parts for automotive
applications. This paper characterizes the elevated-temperature formability of AZ31 magnesium sheet materials and the effect
of processing conditions on the performance of these materials. In addition, magnesium sheet application development at General
Motors Corporation is reviewed. 相似文献
60.
Toshihiko Hoshide Junpei Fujita 《Journal of Materials Engineering and Performance》2008,17(5):627-632
Strength of ground ceramics may be affected by residual stress as well as surface flaws induced by grinding. Strength prediction
for ground ceramics is convenient for mechanical design of ceramic components. In this article, a numerical procedure based
on fracture mechanics was proposed to estimate strength distribution of ground ceramics by considering grinding-induced residual
stress. Bending strength and residual stress of ground ceramics were measured for three grinding-conditions. By comparison
of simulated results with experimental ones, it was revealed that strength characteristics in experiments were well simulated
by using the proposed procedure. 相似文献