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排序方式: 共有304条查询结果,搜索用时 15 毫秒
1.
Dr. D. L. Clements 《Acta Mechanica》1985,56(1-2):31-40
Summary An examination of possible forms of traction free surface wave in anisotropic elastic materials is undertaken. The results yield some interesting features of a certain arbitrariness which exists in displacement waves on a traction free surface in anisotropic media. 相似文献
2.
B. E. Clements H. Godfrin E. Krotscheck H. J. Lautert P. Leiderer C. J. Tymczak 《Journal of Low Temperature Physics》1996,102(1-2):1-9
We compare microscopic calculations of the dynamic structure function of helium films adsorbed to a graphite substrate with neutron scattering data. Starting from a generalized Feynman theory of collective excitations, we include successively, three-phonon interactions, self-energy corrections, and experimental broadening and thereby improve the agreement between theoretical predictions and experiments. The inclusion of three-phonon vertices allows high-lying excited states to decay into lesser energetic ones and thus leads to a natural linewidth. It is shown that the theoretical linewidth of the excitations is typically smaller than the experimental resolution, and that much structure of the spectrum in the neutron scattering data is obscured under a broad plateau between the ripplon and the phonon excitations. This analysis leaves little doubt of the existence of layer-phonons and that the observed shoulder in the dynamic structure function, near the roton minimum, is actually a 2D roton propagating in the inner-most liquid layer. 相似文献
3.
The growing involvement of psychologists in the management of human services, particularly in the public sector, has not been reflected in the development of corresponding academic or practicum training focusing on issues of service delivery. This article gives an overview of the practitioner-manager role and develops a rationale for management-oriented training in doctoral programs. An introductory course is briefly noted, and a review of models, knowledge and skills, and training resources is provided. Also described are practitioner-manager trends, training alternatives, and competing demands of the graduate curriculum. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
R Clements 《Canadian Metallurgical Quarterly》1998,22(5):985-993
Four alcohol screening instruments (the AUDIT, CAGE, MAST, and Svanum's scale) were administered to a sample of 306 undergraduate students at a Midwestern university and were compared with regard to several test characteristics, using the alcohol section of the CIDI-SAM (DSM-IV version) as the criterion measure. The performance of these instruments was evaluated using two subsets of subjects: (1) students who currently met diagnostic criteria for alcohol dependence (n = 35); and (2) students who met diagnostic criteria for alcohol dependence in the past and/or at present (i.e., lifetime diagnosis; n = 50). The AUDIT performed significantly better than the other three instruments in identifying students who were currently alcohol dependent, providing a moderate degree of clinical utility with this group. The four instruments did not differ significantly in their ability to identify students with a lifetime diagnosis; each measure provided only a modest degree of clinical utility with this group. 相似文献
5.
Linda L. Clements 《Journal of Materials Science》1986,21(6):1853-1862
The tensile failure surfaces of (0°)8 T300/5208 graphite-epoxy specimens were examined using both optical and scanning electron microscopy. Fractography was used to determine how moisture content and temperature as well as specimen preparation technique, prepreg batch and cure condition affected the failure mode. A distinctive low-energy failure morphology was found in defective specimens and also in those whose edges were poorly prepared. This morphology was predominant in failures at elevated temperature or moisture content for specimens which had been made from one suspect batch of prepreg. This finding combined with unusual end-tab failures from such specimens indicated that this batch was indeed defective, but that such defective batches could in the future be identified by tests under hot, wet conditions. For specimens made from good prepreg, temperature or moisture appeared to decrease flaw sensitivity and thus increase strength, even though moisture also seemed to increase interfacial debonding between filament and matrix. When combined, moisture and temperature appeared to degrade performance by increasing interfacial debonding and making the epoxy matrix more prone to fracture. 相似文献
6.
7.
As organic farming prohibits the use of synthetic fertilisers, animal slurries and manures must be used. Digestate offers an alternative to these and this study reports on three experiments conducted to determine its usability in terms of: (1) the effect on earthworm populations, (2) its fertilising effects on Italian Ryegrass and wild Creeping Thistle, and (3) the suppression effects digestate has on weed emergence. The results for digestate application to field plots were intermediate between slurry and no treatment for earthworm attraction and wild thistle suppression. In glasshouse trials it led to increased ryegrass growth compared with undigested slurry. Analysis showed that the digestate had improved nitrogen availability, leading to increased plant growth, but a reduced organic matter content compared with the slurry, leading to a positive though less beneficial impact on the earthworms. Digestate therefore provides a suitable fertiliser for organic farming. This suitability could be improved by drying or separation to increase the OM content making its properties closer to those of slurry whilst still retaining the higher content of plant available nitrogen. 相似文献
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9.
Product line engineering has become an important and widely used approach for efficiently developing portfolios of software products. The idea is to develop a set of products as a single, coherent development task from a core asset base (sometimes called a platform), a collection of artifacts specifically designed for use across a portfolio. This approach produces order-of-magnitude economic improvements compared to one-at-a-time software system development. Because the product line approach isn't limited to specific technical properties of the planned software but rather focuses on economic characteristics, high return on investment has become the anthem of the approach's protagonists. Our software product line cost model can calculate the costs and benefits (and hence the ROI) that we can expect to accrue from various product line development situations. It's also straightforward and intuitive. 相似文献
10.
It is a matter of common knowledge that in laboratory hot-dip aluminizing, great difficulties are often encountered in preparing specimens that are free of surface oxides and other ubiquitous contaminants such as oils, grease and dust. Inadequate preparation of specimens will inevitably lead to the prevention of alloy layer growth during hot dipping and poor coatings following withdrawal. This paper describes a method for the production on a laboratory scale of hot-dipped type 1 aluminized sheet- steel specimens of commercial quality. 相似文献