3,805 research outputs found
On unitary convex decompositions of vectors in a -algebra
No full textsummary:By exploiting his recent results, the author further investigates the extent to which variation in the coefficients of a unitary convex decomposition of a vector in a unital -algebra permits the vector decomposable as convex combination of fewer unitaries; certain -algebra results due to M. Rørdam have been extended to the general setting of -algebras
Effects of the spacer and mixing vanes on critical heat flux for low-pressure water at low-velocities
No full textThe effects of spacer grids and mixing vanes on critical heat flux (CHF) have been experimentally investigated for low-pressure water at low, using two different types of test sections: an annulus (19-mm I.D., 33.5-mm O.D., 0.7-m long) and a round tube (10.8-mm I.D. and 0.7-m long). An obstruction-type spacer and a split-vane-type mixing vane were used for the annulus and round tube test sections, respectively. The spacer or mixing vane generally increase the CHF for flow rates higher than a threshold; however, they do not affect or even decrease the CHF under lower flow rates. The major contributing mechanisms would be (a) directing entrained liquid droplets to the heated wall (positive effect) and (b) break-up of the liquid film in annular flow (negative effect)
Removal of sulfur fume by reactive absorption using cobalt-containing absorbents
No full textCobalt sulfide supported on alumina was found to have a potential use as a device trapping elemental sulfur over the temperature range 300-400 (degrees)C. Elemental sulfur in the gas phase can be removed during the deep sulfidation reaction with an accompanying phase change from Co(9)S(8) to CoS(2). Constant removal efficiency above 90% was achieved regardless of concentration difference in the inlet sulfur within a tested range of 900-4500 ppm. The sorbent can be easily regenerated by using hydrogen gas at the temperature range of 350-400 degreesC in a very short time period of less than 1 h. A repeated multicyclic test of absorption and regeneration has shown that the process is reversible and there is no appreciable sintering of particle size.X112sciescopu
Desulfurization of H2S using cobalt-containing sorbents at low temperatures
No full textThe sulfidation of cobalt oxide with H2S was proposed for the desulfurization process at low temperatures. The reaction is studied with a packed-bed reactor and TGA (thermogravimetric analysis) equipped with in situ reactor experiments in the range 300-500 degreesC. Due to larger particle size, the bulk cobalt oxide showed slower sulfidation rate having insufficient removal efficiency. Supported cobalt oxide exhibited high removal efficiency and degree of sulfidation at 300-400 degreesC primarily because of its smaller grain size. Among the three sorbents tested, extremely low values of activation energy and frequency factor were observed in Co3O4/TiO2; the rate was almost independent of temperature. The experimental data were successfully predicted by shrinking core model having a bimodal distribution in grain size. From the calculated effective diffusivity, D-e, and kinetic constant, k, the diffusion resistance controlled the overall reaction rate of bulk oxide sorbent. (C) 2004 Elsevier Ltd. All rights reserved.X1131sciescopu
Erratum: Half-supersymmetric solutions in five-dimensional supergravity (Journal of High Energy Physics (2007) 12 (025))
No full text[No abstract available]Gutowski JB, 2007, J HIGH ENERGY PHYS11
Surjective isometries between unitary sets of unital JB∗-algebras
No full textWe would like to thank Prof. Lajos Molnár for encouraging us to explore this problem.
We are also indebted to the anonymous reviewer for several useful comments.
First and fifth authors partially supported by the Spanish Ministry of Science, Innovation and Universities (MICINN) and European Regional Development Fund project
no. PGC2018-093332-B-I00, Programa Operativo FEDER 2014-2020 and Consejería de
Economía y Conocimiento de la Junta de Andalucía grant numbers A-FQM-242-UGR18
and FQM375. First author partially supported by EPSRC (UK) project “Jordan Algebras, Finsler Geometry and Dynamics” ref. no. EP/R044228/1. Second author partially
supported by JSPS KAKENHI Grant Number JP 21J21512. Fourth author partially
supported by JSPS KAKENHI (Japan) Grant Number JP 20K03650.
* Funding for open access charge: Universidad de Granada / CBUAThis paper is, in a first stage, devoted to establishing a topological–algebraic characterization of the principal component, U0(M), of the set of unitary elements, U(M), in a unital JB⁎-algebra M. We arrive to the conclusion that, as in the case of unital C⁎-algebras, U0(M)=M1−1∩U(M)={Ue⋯Ue(1):n∈N,hj∈Msa∀1≤j≤n}={u∈U(M): there exists w∈U0(M) with ‖u−w‖<2} is analytically arcwise connected. Actually, U0(M) is the smallest quadratic subset of U(M) containing the set eiM. Our second goal is to provide a complete description of the surjective isometries between the principal components of two unital JB⁎-algebras M and N. Contrary to the case of unital C⁎-algebras, we shall deduce the existence of connected components in U(M) which are not isometric as metric spaces. We shall also establish necessary and sufficient conditions to guarantee that a surjective isometry Δ:U(M)→U(N) admits an extension to a surjective linear isometry between M and N, a conclusion which is not always true. Among the consequences it is proved that M and N are Jordan ⁎-isomorphic if, and only if, their principal components are isometric as metric spaces if, and only if, there exists a surjective isometry Δ:U(M)→U(N) mapping the unit of M to an element in U0(N). These results provide an extension to the setting of unital JB⁎-algebras of the results obtained by O. Hatori for unital C⁎-algebras.CBUAConsejería de Economía y Conocimiento de la Junta de Andalucía
A-FQM-242-UGR18, FQM375Ministerio de Ciencia, Innovación y UniversidadesEngineering and Physical Sciences Research Council
EP/R044228/1Universidad de GranadaMinisterio de Ciencia e InnovaciónJapan Society for the Promotion of Science JP 20K03650, JP 21J21512European Regional Development Fund
PGC2018-093332-B-I0
Zu ni zhen zi de xian kong jian jie gou yu ha mi dun li lun
No full textChee Shiu Chung = 阻尼振子的線空間結構與哈密頓理論 / 朱兆中.Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.Includes bibliographical references (leaves 88).Text in English; abstracts in English and Chinese.Chee Shiu Chung = Zu ni zhen zi de xian kong jian jie gou yu ha mi dun li lun / Zhu Zhaozhong.Chapter 1 --- Introduction --- p.1Chapter 2 --- Conservative Systems --- p.4Chapter 2.1 --- General Formalism --- p.4Chapter 2.2 --- One Simple Harmonic Oscillator --- p.7Chapter 2.3 --- Two Coupled Harmonic Oscillators --- p.9Chapter 3 --- Dissipative Systems --- p.12Chapter 3.1 --- Elimination of Bath --- p.12Chapter 3.2 --- One Oscillator with Dissipation --- p.16Chapter 3.3 --- Two Oscillators with Dissipation --- p.19Chapter 4 --- Eigenvector Expansion and Bilinear Map --- p.21Chapter 4.1 --- Formalism --- p.21Chapter 4.2 --- Inner Product and Bilinear Map --- p.23Chapter 4.3 --- Normalization and Phase --- p.25Chapter 4.4 --- Matrix Representation --- p.25Chapter 4.5 --- Duality --- p.28Chapter 5 --- Applications and Examples of Eigenvector Expansion --- p.31Chapter 5.1 --- Single Oscillator --- p.31Chapter 5.2 --- Two Oscillators --- p.32Chapter 5.3 --- Uneven Damping --- p.33Chapter 6 --- Time Evolution --- p.36Chapter 6.1 --- Initial-Value Problem --- p.36Chapter 6.1.1 --- Green's Function --- p.37Chapter 6.2 --- Sum Rules --- p.39Chapter 7 --- Time-Independent Perturbation Theory --- p.41Chapter 7.1 --- Non-degenerate Perturbation --- p.41Chapter 7.2 --- Degenerate Perturbation Theory --- p.46Chapter 8 --- Jordan Block --- p.48Chapter 8.1 --- Jordan Normal Basis --- p.48Chapter 8.1.1 --- Construction of Basis Vectors --- p.48Chapter 8.1.2 --- Bilinear Map --- p.50Chapter 8.1.3 --- Example of Jordan Normal Basis --- p.55Chapter 8.2 --- Time Evolution --- p.56Chapter 8.2.1 --- Time Dependence of Basis Vectors --- p.56Chapter 8.2.2 --- Initial-Value Problem --- p.58Chapter 8.2.3 --- Green's Function --- p.59Chapter 8.2.4 --- Sum Rules --- p.60Chapter 8.3 --- Jordan Block Perturbation Theory --- p.61Chapter 8.3.1 --- Lowest Order Perturbation --- p.61Chapter 8.3.2 --- Higher-Order Perturbation --- p.65Chapter 8.3.3 --- Non-generic Perturbations --- p.66Chapter 8.4 --- Examples of High-Order Criticality --- p.66Chapter 8.4.1 --- Fourth-order JB --- p.67Chapter 8.4.2 --- Third-order JB --- p.74Chapter 8.4.3 --- Two Second-order JB --- p.79Chapter 9 --- Conclusion --- p.81Chapter A --- Appendix --- p.83Chapter A.l --- Fourier Transform and Contour Integration --- p.83Chapter B --- Degeneracy and Criticality --- p.86Bibliography --- p.8
Flexible time–space network formulation and hybrid metaheuristic for conflict-free and energy-efficient path planning of automated guided vehicles
No full textOperations of Automated Guided Vehicles (AGVs) are desired to be more energy-efficient while maintaining high transport productivity, motivated by the green production requirements. This paper investigates a new energy-efficient planning problem for determining conflict-free paths of the AGVs in its transport roadmap. In this problem, the vehicle path and transport time in the roadmap are jointly optimized, based on a flexible time–space network (FTSN). We provide the mathematical problem formulation of the energy-efficient path planning problem. The resulting optimization problem is proved to be a non-convex mixed-integer nonlinear programming which is computationally intractable. We further propose a hybrid metaheuristic that integrates the genetic algorithm and estimation of the distribution algorithm to improve its computational efficiency. Numerical results show the effectiveness of the developed algorithm based on the FTSN framework, compared to the existing metaheuristics, the conventional path planning method, and a commercial solver. The proposed method has a wide application in improving energy use of material handling, providing a guiding significance on promoting cleaner production of flexible manufacturing systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
Decoupling of genome size and sequence divergence in a symbiotic bacterium
No full textAuthor Posting. © American Society for Microbiology, 2000. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Journal of Bacteriology 182 (2000): 3867-3869, doi:10.1128/JB.182.13.3867-3869.2000.In contrast to genome size variation in most bacterial taxa, the small genome size of Buchnera sp. was shown to be highly conserved across genetically diverse isolates (630 to 643 kb). This exceptional size conservation may reflect the inability of this obligate mutualist to acquire foreign DNA and reduced selection for genetic novelty within a static intracellular environment.Financial support was provided by a National Institute of Health
postdoctoral training grant to J.J.W. (Center for Insect Science, University
of Arizona) and a National Science Foundation grant (DEB-
9815413) to N.A.M
- …
