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11.
Ivar Jacobson Shihong Huang Mira Kajko-Mattsson Paul McMahon Ed Seymour 《Programming and Computer Software》2012,38(1):1-12
The purpose of writing this Three Year Vision paper is threefold. Firstly, it briefly recaps the progress Semat has made thus
far; secondly, it lays out the future directions for people working actively within the Semat community; thirdly, it provides
the background for seeking funding support from agencies, such as the European Community and the like. Funding support is
necessary to sustain the ongoing activities of Semat and its growth into a broader community effort, as most people working
within Semat are volunteers. As such, the paper may be both too much and too little for the wider supporter base. However,
we intend to make our work fully transparent, hence, we publish it widely. We seek feedback and comments from supporters and
signatories in order to improve the vision. In this context, other companion papers are being written to better address the
specific needs for the practitioners, the industry and the academia. 相似文献
12.
John J. Petrovic Maria I. Pena Ivar E. Reimanis Michael S. Sandlin Samuel D. Conzone H. Harriet Kung Darryl P. Butt 《Journal of the American Ceramic Society》1997,80(12):3070-3076
The mechanical behavior of MoSi2 reinforced–Si3 N4 matrix composites was investigated as a function of MoSi2 phase content, MoSi2 phase size, and amount of MgO densification aid for the Si3 N4 phase. Coarse-phase MoSi2 -Si3 N4 composites exhibited higher room-temperature fracture toughness than fine-phase composites, reaching values >8 MP·am1/2 . Composite fracture toughness levels increased at elevated temperature. Fine-phase composites were stronger and more creep resistant than coarse phase composites. Room-temperature strengths >1000 MPa and impression creep rates of ∼10−8 s−1 at 1200°C were observed. Increased MgO levels generally were deleterious to MoSi2 -Si3 N4 mechanical properties. Internal stresses due to MoSi2 and Si3 N4 thermal expansion coefficient mismatch appeared to contribute to fracture toughening in MoSi2 -Si3 N4 composites. 相似文献
13.
Mechanical and optical properties in precipitated regions of alumina‐rich magnesium aluminate spinel
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Jesse Miller Ivar Reimanis Weiguo Miao Jonathan Salem 《International Journal of Applied Ceramic Technology》2017,14(2):236-244
The toughening and strengthening of transparent ceramics is challenging because microstructural alterations typically lead to light scattering. Here, controlled precipitation of α‐Al2O3 from nonstoichiometric spinel is explored to demonstrate unique control over the evolution of second phase Al2O3 and how the microstructure might be altered to enhance fracture toughness while minimizing light scatter. Alumina‐rich magnesium aluminate spinel, MgO·nAl2O3, where n=2, was hot pressed and HIPed to produce fully dense, single‐phase material. The material was then heat treated in air at 1573 K for up to 20 hours to create a two‐phase spinel‐Al2O3 composite. The fracture toughness varies from 0.88 to 2.47 MPa√m depending on the microstructure; enhanced toughness at the surface was due to increased crack tortuosity at phase boundaries, but residual tensile stresses were observed in the interior of the material. Precipitation causes local volume contraction and the formation of porosity, decreasing optical transmission, especially for heat treatment times longer than 5 hours. 相似文献
14.
Ivar Jacobson Steve Cook 《程序员》2010,(7):134-136
UML(统一建模语言)成为标准已经超过12年了。在这些年里,人们对UML的看法各不相同,有喜爱的,也有讨厌的。在这篇文章中,我们将讨论当前UML规范的不足之处.并建议如何让它敏捷、更精益、更智慧、更有弹性——简而言之, 相似文献
15.
Subramanian Ramalingam Corinne E. Packard Ivar E. Reimanis 《Journal of the American Ceramic Society》2013,96(6):1909-1915
β‐eucryptite (LiAlSiO4), a member of the family of lithium aluminum silicates, is known to undergo a reversible pressure‐induced phase transformation at ~0.8 GPa to ε‐eucryptite. This study correlates the results between two techniques, in situ diamond anvil cell–Raman spectroscopy and nanoindentation experiments, to explore how doping (substituting Zn for Li) influences this pressure‐induced phase transformation. Diamond anvil cell tests carried up to 3 GPa hydrostatic stress under Raman spectroscopy were compared with nanoindentation results, which provide a more localized, multiaxial stress state. The results indicate that the magnitude of hysteresis observed (difference between the pressures required for the forward and reverse transformation) is lower for Zn‐doped β‐eucryptite; however, the onset of the phase transformation is unchanged by doping with Zn. Furthermore, calculations of activation volume from nanoindentation experiments yield similar values (~0.1 nm3) for pure and Zn‐doped β‐eucryptite, suggesting that the nucleation event that establishes the onset of the phase transformation is the same for both materials. 相似文献
16.
Scientometrics - At the Leibniz Institute for Baltic Sea Research Warnemünde (the home institute of this paper), scientists have been exploring the common denominator between microplastics and... 相似文献
17.
Ove Wolfgang Arne Haugstad Birger Mo Anders Gjelsvik Ivar Wangensteen Gerard Doorman 《Energy》2009,34(10):1642
The Norwegian Energy Act that came into force in 1991 deregulated the electricity market and removed the former obligation power companies had to supply electricity to the geographical area they were responsible for. Hence producers can supply electricity on the basis of profitability. In 2007 the Energy Act was evaluated by the Government. As a part of this, a study concerning hydro reservoir handling before and after deregulation was carried out by SINTEF. Public statistics show that average hydro reservoir levels measured in per cent of reservoir capacity have been reduced after 1990. We have used the power-market model EMPS1 (EFI's Multi-area Power-market Simulator) to analyze if this reduction can be explained by natural variation in climatic variables or by structural changes that have occurred after 1990. Simulation results show that the reduced reservoir levels cannot be explained by natural variation in climatic variables. Structural changes such as increased transmission capacities can, however, explain some of the reduction. Our study does not indicate that the present reservoir handling gives reservoir levels that are too low. In this paper we also describe the stochastic dynamic optimization problem for long-term hydropower scheduling, and we explain how this problem actually is solved by the EMPS model. 相似文献
18.
A review of the densification mechanisms and the microstructural development for transparent spinel made by free sintering and by hot pressing is given. The paper is divided into two main parts. The first part considers spinel without any sintering additives because there still is some controversy concerning the role of cation stoichiometry on sintering and grain growth. The second part discusses the role of the classic sintering aid, LiF, in processing transparent spinel. LiF is shown to have multiple behaviors: (1) it initially wets spinel and forms a liquid phase at relatively low temperatures, which affects early-stage densification and also grain growth; (2) upon cooling from intermediate temperatures, or even from higher temperatures if microstructure evolution (e.g., formation of closed porosity) prevents volatization, the LiF-containing liquid dewets and resides in isolated pockets; (3) LiF alters the cation stoichiometry, thereby enhancing diffusion via an increase in the concentration of oxygen vacancies; this affects both the densification rate and grain growth; and (4) it reacts with impurities in the system, thereby acting as a cleanser. For the production of transparent spinel, it is critical that LiF or associated reaction products not be retained as a secondary phase. 相似文献
19.
Use of Electric Fields to Monitor the Dynamical Aspect of Cell Behavior in Tissue Culture 总被引:6,自引:0,他引:6
Mammalian cells can be cultured and therefore studied in vitro. Normally, the cells' morphology and other static properties are observed with the aid of a light microscope. A method is described here that allows observation of the dynamical aspects of cultured cells. Mammalian fibroblasts are cultured in polystyrene dishes that contain evaporated gold electrodes. As the cells attach to the electrodes, their presence and their motion is directly reflected in the measured impedance. 相似文献
20.
Application of proteomics to understand the molecular mechanisms behind meat quality 总被引:1,自引:0,他引:1
The proteome is expressed from the genome, influenced by environmental and processing conditions, and can be seen as the molecular link between the genome and the functional quality characteristics of the meat. In contrast to traditional biochemical methods where one protein is studied at a time, several hundred proteins can be studied simultaneously. Proteomics is a promising and powerful tool in meat science and this is reflected by the increasing number of studies emerging in the literature using proteomics as the key tool to unleash the molecular mechanisms behind different genetic backgrounds or processing techniques of meat. Thus understanding the variations and different components of the proteome with regard to a certain meat quality or process parameter will lead to knowledge that can be used in optimising the conversion of muscles to meat. At present, there has been focus on development of techniques and mapping of proteomes according to genotypes and muscle types. In the future, focus should be more towards understanding and finding markers for meat quality traits. This review will focus on the methods used in the published proteome analyses of meat, with emphasis on the challenges related to statistical analysis of proteome data, and on the different topics of meat science that are investigated. 相似文献