177,043 research outputs found
Inquinamento ambientale e gravidanza: effetti embrio-feto-tossici nel Mus rattus albinus, di gas di motore a scoppio e di fumo tabagico passivo
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Multi-objective optimisation of a semi-planing hull using CFD RANSE simulations with low number of cells
No full textABSTRACT: An integrated use of a CFD software with an algorithm for multi-objective optimization is proposed in this paper.
Currently, optimisations regarding hydrodynamic performance for a given ship or marine vehicle design (eg. choice of best shape for the minimization of wave resistance) can be carried out interfacing multiobjective algorithms with parametric 3D modelers and suitable hydrodynamic solvers. Having to manipulate a great number of alternatives, the requirement for the computing chain is to rely on fast and tested methodologies especially for the flow solvers.
The use of RANS viscous CFD simulations offers more complete and detailed information to evaluate the resistance and the flow around ships hulls and is now well established. These methods, however generally require to represent the flow domain by a high number of cells with consequent substantial increase of hardware and computing time requirements.
A research has been carried out to define and standardize operating modes to carry out viscous simulations with a number of cells as low as possible. It has allowed to obtain adequate results within a reasonable short time and without the necessity of requiring high computing resources.
In this way it is possible to achieve adequate RANS simulations in a short time so as to make them competitive as far as computational costs with panel methods also in optimization problems, especially in the evaluation phase of many different design alternatives.
The optimization of a hard-chine semi-planing hull, based on the reduction of the total resistance at two different speeds through the integration of software optimisation with the RANS simulations with low number of cells has been performed and is presented and discussed.
The results obtained are validated by experimental tests in towing tank
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Topographic Fingerprint of Deep Mantle Subduction
No full textThe dynamic topography links with the mantle structures at various temporal and spatial scales. However, it is still unclear how it relates to the dynamics of subducting lithosphere when plates reach the mantle transition zone and lower mantle. Seismic tomography images show how slab morphologies vary from sinking subvertically into the lower mantle, to lying flat above the upper-lower mantle discontinuity, to thickening in the shallow lower mantle. These slab shapes have been considered to be the result of variable interaction of the slab with the upper-lower mantle discontinuity at ~670 km depth. Previous studies show that periodic deep slab dynamics can explain a variety of enigmatic geological and geophysical observations such as periodic variations of the plate velocities, trench retreat and advance episodes, and the scattered distribution of slab dip angle in the upper mantle. In this study, we use two-dimensional subduction models to investigate the surface topography expression and its evolution during slab transition zone interaction. Our models show that topography does not depend on slab morphology; indeed, the dynamic topography cannot distinguish between a slab sinking straight into the lower mantle and slab stagnation at the upper-lower mantle boundary. However, topographic oscillations are related to episodes of the trench advance and retreat, which in turn are linked to the slab folding behavior at transition zone depths. Our results suggest that the surface transient signal observed by geological studies could help to detect deep subduction dynamics
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Recipient-born bloodstream infection due to extensively drug-resistant Acinetobacter baumannii after emergency heart transplant: report of a case and review of the literature.
No full textLetter from R. R. Zellick, Assistant Trust Officer, Anglo California National Bank of San Francisco, to Joseph R. Goodman, October 2, 1942
No full textLetter from R. R. Zellick, Assistant Trust Officer at The Anglo California National Bank of San Francisco, to Joseph R. Goodman, regarding property owned by Dave Tatsuno. Zellick mentions a dispute between current tenants and Tatsuno, and that Tatsuno has asked Goodman to help locate trustworthy tenants.Personal correspondence, organizational records, government documents, publications, and other papers created or collected by Joseph R. Goodman documenting the forced removal and incarceration of Japanese Americans during World War II, as well as organized resistance to incarceration. Included in the collection are records of the Japanese Young Men's Christian Association and the Japanese American Citizens' League in San Francisco, including papers of the Japanese YMCA's executive secretary Lincoln Kanai; Sakai family papers; Goodman's correspondence to and from Japanese American incarcerees, organizations opposing forced removal and incarceration of Japanese Americans, the War Relocation Authority, and others; publications, photographs, and ephemera from the Topaz Relocation Center, where Goodman taught high school; War Relocation Authority records and publications; and newspaper clippings, pamphlets, and reports about forced removal and incarceration created by various government, religious, and civic organizations, in California and nationwide
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