The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform
Howard Brenner - One of the best experts on this subject based on the ideXlab platform.
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body versus surface forces in continuum mechanics is the maxwell stress tensor a physically objective cauchy stress
Physical Review E, 2002Co-Authors: Carlos Rinaldi, Howard BrennerAbstract:The Maxwell stress tensor (MST) ${\mathbf{T}}^{M}$ plays an important role in the dynamics of continua interacting with external fields, as in the commercially and scientifically important case of ``ferrofluids.'' As a Conceptual Entity in quasistatic systems, the MST derives from the definition ${\mathbf{f}}^{M}\stackrel{\mathrm{def}.}{=}\mathbf{\ensuremath{\nabla}}\ensuremath{\cdot}{\mathbf{T}}^{M},$ where ${\mathbf{f}}^{M}(\mathbf{x})$ is a physically objective volumetric external body-force density field at a point $\mathbf{x}$ of a continuum, derived from the solution of the pertinent governing equations. Beginning with the fact that ${\mathbf{T}}^{M}$ is not uniquely defined via the preceding relationship from knowledge of ${\mathbf{f}}^{M},$ we point out in this paper that the interpretation of ${\mathbf{T}}^{M}$ as being a physical stress is not only Conceptually incorrect, but that in commonly occuring situations this interpretation will result in incorrect predictions of the physical response of the system. In short, by elementary examples, this paper emphasizes the need to maintain the classical physical distinction between the notions of body forces $\mathbf{f}$ and stresses $\mathbf{T}.$ These examples include calculations of the torque on bodies, the work required to deform a fluid continuum, and the rate of interchange of energy between mechanical and other modes.
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body versus surface forces in continuum mechanics is the maxwell stress tensor a physically objective cauchy stress
Physical Review E, 2002Co-Authors: Carlos Rinaldi, Howard BrennerAbstract:The Maxwell stress tensor (MST) T(M) plays an important role in the dynamics of continua interacting with external fields, as in the commercially and scientifically important case of "ferrofluids." As a Conceptual Entity in quasistatic systems, the MST derives from the definition f(M)def=inverted Delta x T(M), where f(M)(x) is a physically objective volumetric external body-force density field at a point x of a continuum, derived from the solution of the pertinent governing equations. Beginning with the fact that T(M) is not uniquely defined via the preceding relationship from knowledge of f(M), we point out in this paper that the interpretation of T(M) as being a physical stress is not only Conceptually incorrect, but that in commonly occuring situations this interpretation will result in incorrect predictions of the physical response of the system. In short, by elementary examples, this paper emphasizes the need to maintain the classical physical distinction between the notions of body forces f and stresses T. These examples include calculations of the torque on bodies, the work required to deform a fluid continuum, and the rate of interchange of energy between mechanical and other modes.
Carlos Rinaldi - One of the best experts on this subject based on the ideXlab platform.
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body versus surface forces in continuum mechanics is the maxwell stress tensor a physically objective cauchy stress
Physical Review E, 2002Co-Authors: Carlos Rinaldi, Howard BrennerAbstract:The Maxwell stress tensor (MST) ${\mathbf{T}}^{M}$ plays an important role in the dynamics of continua interacting with external fields, as in the commercially and scientifically important case of ``ferrofluids.'' As a Conceptual Entity in quasistatic systems, the MST derives from the definition ${\mathbf{f}}^{M}\stackrel{\mathrm{def}.}{=}\mathbf{\ensuremath{\nabla}}\ensuremath{\cdot}{\mathbf{T}}^{M},$ where ${\mathbf{f}}^{M}(\mathbf{x})$ is a physically objective volumetric external body-force density field at a point $\mathbf{x}$ of a continuum, derived from the solution of the pertinent governing equations. Beginning with the fact that ${\mathbf{T}}^{M}$ is not uniquely defined via the preceding relationship from knowledge of ${\mathbf{f}}^{M},$ we point out in this paper that the interpretation of ${\mathbf{T}}^{M}$ as being a physical stress is not only Conceptually incorrect, but that in commonly occuring situations this interpretation will result in incorrect predictions of the physical response of the system. In short, by elementary examples, this paper emphasizes the need to maintain the classical physical distinction between the notions of body forces $\mathbf{f}$ and stresses $\mathbf{T}.$ These examples include calculations of the torque on bodies, the work required to deform a fluid continuum, and the rate of interchange of energy between mechanical and other modes.
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body versus surface forces in continuum mechanics is the maxwell stress tensor a physically objective cauchy stress
Physical Review E, 2002Co-Authors: Carlos Rinaldi, Howard BrennerAbstract:The Maxwell stress tensor (MST) T(M) plays an important role in the dynamics of continua interacting with external fields, as in the commercially and scientifically important case of "ferrofluids." As a Conceptual Entity in quasistatic systems, the MST derives from the definition f(M)def=inverted Delta x T(M), where f(M)(x) is a physically objective volumetric external body-force density field at a point x of a continuum, derived from the solution of the pertinent governing equations. Beginning with the fact that T(M) is not uniquely defined via the preceding relationship from knowledge of f(M), we point out in this paper that the interpretation of T(M) as being a physical stress is not only Conceptually incorrect, but that in commonly occuring situations this interpretation will result in incorrect predictions of the physical response of the system. In short, by elementary examples, this paper emphasizes the need to maintain the classical physical distinction between the notions of body forces f and stresses T. These examples include calculations of the torque on bodies, the work required to deform a fluid continuum, and the rate of interchange of energy between mechanical and other modes.
Tuan Anh Nguyen - One of the best experts on this subject based on the ideXlab platform.
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Adding support to XACML for multi-domain user to user dynamic delegation of authority
International Journal of Information Security, 2009Co-Authors: David W. Chadwick, Sassa Otenko, Tuan Anh NguyenAbstract:We describe adding support for dynamic delegation of authority (DOA) between users in multiple administrative domains, to the XACML model for authorisation decision making. DOA is enacted via the issuing of credentials from one user to another, and follows the role based access control model. We present the problems and requirements that such a delegation model demands, the policy elements that are necessary to control the delegation chains and a description of the architected solution. We propose a new Conceptual Entity called the credential validation service (CVS) to work alongside the XACML PDP. We describe our implementation of the CVS and present performance measurements for validating delegated chains of credentials.
Paolo Papotti - One of the best experts on this subject based on the ideXlab platform.
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SEBD - Searching Entities on the Web by Sample
2008Co-Authors: Lorenzo Blanco, Valter Crescenzi, Paolo Merialdo, Paolo PapottiAbstract:Several Web sites deliver a large number of pages, each publishing data about one instance of some real world Entity, such as an athlete, a stock quote, a book. Despite it is easy for a human reader to recognize these instances, current search engines are unaware of them. Technologies for the Semantic Web aim at achieving this goal; however, so far they have been of little help in this respect, as semantic publishing is very limited. The paper describes a method to automatically search on the Web for pages that publish data representing an instance of a certain Conceptual Entity. Our method takes as input a small set of sample pages: it automatically infers a description of the underlying Conceptual Entity and then searches the Web for other pages containing data representing the same Entity. We have implemented our method in a system prototype, which has been used to conduct several experiments that have produced interesting results.
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WIDM - Supporting the automatic construction of Entity aware search engines
Proceeding of the 10th ACM workshop on Web information and data management - WIDM '08, 2008Co-Authors: Lorenzo Blanco, Valter Crescenzi, Paolo Merialdo, Paolo PapottiAbstract:Several web sites deliver a large number of pages, each publishing data about one instance of some real world Entity, such as an athlete, a stock quote, a book. Although it is easy for a human reader to recognize these instances, current search engines are unaware of them. Technologies for the Semantic Web aim at achieving this goal; however, so far they have been of little help in this respect, as semantic publishing is very limited. We have developed a method to automatically search on the web for pages that publish data representing an instance of a certain Conceptual Entity. Our method takes as input a small set of sample pages: it automatically infers a description of the underlying Conceptual Entity and then searches the web for other pages containing data representing the same Entity. We have implemented our method in a system prototype, which has been used to conduct several experiments that have produced interesting results.
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EDBT - Flint: Google-basing the Web
Proceedings of the 11th international conference on Extending database technology Advances in database technology - EDBT '08, 2008Co-Authors: Lorenzo Blanco, Valter Crescenzi, Paolo Merialdo, Paolo PapottiAbstract:Several Web sites deliver a large number of pages, each publishing data about one instance of some real world Entity, such as an athlete, a stock quote, a book. Even though it is easy for a human reader to recognize these instances, current search engines are unaware of them. Technologies for the Semantic Web aim at achieving this goal; however, so far they have been of little help in this respect, as semantic publishing is very limited. We have developed a system, called Flint, for automatically searching, collecting and indexing Web pages that publish data representing an instance of a certain Conceptual Entity. Flint takes as input a small set of labeled sample pages: it automatically infers a description of the underlying Conceptual Entity and then searches the Web for other pages containing data representing the same Entity. Flint automatically extracts data from the collected pages and stores them into a semi-structured self-describing database, such as Google Base. Also, the collected pages can be used to populate a custom search engine; to this end we rely on the facilities provided by Google Co-op.
Paul Jackson - One of the best experts on this subject based on the ideXlab platform.
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Transactive directories of organizational memory: Towards a working data model
Information & Management, 2012Co-Authors: Paul JacksonAbstract:Transactive memory system is a term from group psychology that describes a system that helps small groups maintain and use personal directories to allocate and retrieve knowledge. Such systems have been observed at the level of whole organizations, suggesting that they provide a means for Conceptualizing the exploitation of organizational memory. In this paper, I describe a longitudinal investigation of a global engineering consulting firm in which I used inductive analysis of interview data to map and then develop a Conceptual Entity-relationship model of organizational memory. This model formed the basis for a transactive directory to facilitate knowledge retrieval and allocation in the firm.
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An Exploratory Survey of the Structure and Components of Organizational Memory
Becoming Virtual, 1Co-Authors: Paul JacksonAbstract:This chapter uses the concepts of organizational memory (OM) and organizational learning to analyze social, practical and technical issues facing corporate memory utilization in the distributed organizational setting of Unit 2. It advances our understanding of how to Conceptualize, map and therefore manage and use OM by using inductive analysis of qualitative data to develop a Conceptual Entity-relationship model. This model refines and specifies our understanding of the concept of OM and its constituent elements, providing a theoretically based and empirically validated description which can be used as a platform for designing solutions to facilitate knowledge sharing in distributed organizations.
