148 research outputs found
Hypocoercivity for Kolmogorov backward evolution equations and applications
In this article we extend the modern, powerful and simple abstract Hilbert
space strategy for proving hypocoercivity that has been developed originally by
Dolbeault, Mouhot and Schmeiser. As well-known, hypocoercivity methods imply an
exponential decay to equilibrium with explicit computable rate of convergence.
Our extension is now made for studying the long-time behavior of some strongly
continuous semigroup generated by a (degenerate) Kolmogorov backward operator
L. Additionally, we introduce several domain issues into the framework.
Necessary conditions for proving hypocoercivity need then only to be verified
on some fixed operator core of L. Furthermore, the setting is also suitable for
covering existence and construction problems as required in many applications.
The methods are applicable to various, different, Kolmogorov backward evolution
problems. As a main part, we apply the extended framework to the (degenerate)
spherical velocity Langevin equation. The latter can be seen as some kind of an
analogue to the classical Langevin equation in case spherical velocities are
required. This model is of important industrial relevance and describes the
fiber lay-down in the production process of nonwovens. For the construction of
the strongly continuous contraction semigroup we make use of modern
hypoellipticity tools and pertubation theory
RITUAL, TIME, AND ENTERNITY
It is argued here that the construction of time and eternity are among ritual's entailments. In dividing continuous duration into distinct periods ritual distinguishes two temporal conditions: (1) that prevailing in mundane periods and (2) that prevailing during the intervals between them. Differences in the frequency, length, and relationship among the rituals constituting different liturgical orders are considered, as are differences between mundane periods and ritual's intervals with respect to social relations, cognitive modes, meaningfulness, and typical interactive frequencies. Periods, it is observed, relate to intervals as everchanging to never-changing, and close relationships of never changing to eternity, eternity to sanctity, and sanctity to truth are proposed. In the argument that ritual's âtimes out of timeâ really are outside mundane time, similarities to the operations of digital computers and Herbert Simon's discussion of interaction frequencies in the organization of matter are noted.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72989/1/j.1467-9744.1992.tb00996.x.pd
Integration of the environmental management aspect in the optimization of the design and planning of energy systems
The increasing concerns regarding the environmental pollution derived from anthropogenic activities, such as the use of fossil fuels for power generation, has driven many interested parties to seek different alternatives, e.g. use of renewable energy sources, use of âcleanerâ fuels and use of more effective technologies, in order to minimize and control the quantity of emissions that are produced during the life cycle of conventional energy sources. In addition to these alternatives, the use of an integrated procedure in which the environmental aspect will be taken into account during the design and planning of energy systems could provide a basis on which emissions reduction will be dealt with a life cycle approach. The work presented in this paper focuses on the examination of the possibilities of integrating the environmental aspects in the preliminary phase of the conventional design and planning of energy systems in conjunction with other parameters, such as financial cost, availability, capacity, location, etc. The integration of the environmental parameter to the design is carried out within a context where Eco-design concepts are applied. Due to the multi-parameter nature of the design procedure, the tools that are used are Life Cycle Analysis and Multi-criteria Analysis. The proposed optimization model examines and identifies optimum available options of the use of different energy sources and technologies for the production of electricity and/or heat by minimizing both the financial cost and the environmental impacts, with regard to a multiple objective optimization subject to a set of specific constraints. Implementation of the proposed model in the form of a case study for the island of Rhodes in Greece revealed that an optimized solution both cost and environmental-wise, would be an almost balanced participation of renewables and non-renewable energy sources in the energy mix
Conférence de M. Haym Soloveitchik
Soloveitchik Haym. ConfĂ©rence de M. Haym Soloveitchik. In: Ăcole pratique des hautes Ă©tudes, Section des sciences religieuses. Annuaire. Tome 107, 1998-1999. 1998. pp. 231-233
Conférence de M. Haym Soloveitchik
Soloveitchik Haym. ConfĂ©rence de M. Haym Soloveitchik. In: Ăcole pratique des hautes Ă©tudes, Section des sciences religieuses. Annuaire. Tome 107, 1998-1999. 1998. pp. 231-233
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