The present paper generalizes to semitopological and quasitopological groups some results achieved by Horst Herrlich and the second author for topological groups. The results concern preserving products in coreflective subcategories. Unlike in paratopological or topological groups, there are non-finitely productive bicoreflective subcategories of quasitopological groups. We desctribe bicoreflective subcategories of semitopological groups that are either finitely productive or productive or their productivity number is submeasurable. To achieve the results, several general factorization theorems for maps on products will be proved with the help of modification of NSS property of groups. 相似文献
It was conjectured by the first author and Peetre that the higher Laplace–Beltrami operators generate the whole ring of invariant operators on bounded symmetric domains. We give a proof of the conjecture for domains of rank ≤ 6 by using a graph manipulation of K¨ahler curvature tensor. We also compute higher order terms in the asymptotic expansions of the Bergman kernels and the Berezin transform on bounded symmetric domain. 相似文献
Bisimulations have been widely used in many areas of computer science to model equivalence between various systems, and to reduce the number of states of these systems, whereas uniform fuzzy relations have recently been introduced as a means to model the fuzzy equivalence between elements of two possible different sets. Here we use the conjunction of these two concepts as a powerful tool in the study of equivalence between fuzzy automata. We prove that a uniform fuzzy relation between fuzzy automata A and B is a forward bisimulation if and only if its kernel and co-kernel are forward bisimulation fuzzy equivalence relations on A and B and there is a special isomorphism between factor fuzzy automata with respect to these fuzzy equivalence relations. As a consequence we get that fuzzy automata A and B are UFB-equivalent, i.e., there is a uniform forward bisimulation between them, if and only if there is a special isomorphism between the factor fuzzy automata of A and B with respect to their greatest forward bisimulation fuzzy equivalence relations. This result reduces the problem of testing UFB-equivalence to the problem of testing isomorphism of fuzzy automata, which is closely related to the well-known graph isomorphism problem. We prove some similar results for backward-forward bisimulations, and we point to fundamental differences. Because of the duality with the studied concepts, backward and forward-backward bisimulations are not considered separately. Finally, we give a comprehensive overview of various concepts on deterministic, nondeterministic, fuzzy, and weighted automata, which are related to bisimulations. 相似文献
We propose a universal method of computation of thermal noise in mirrors of gravitational wave interferometers based on first principles. We imagine a situation where a mirror is part of a Fabry–Perot cavity. The movement of the mirror's surface produces variation of the eigen frequency of the cavity, which is computed by evaluating the variation of the energy stored in cavity. We consider two particular examples: first, the thermal noise from a dielectric slab inside the Fabry–Perot cavity, and second, the polarization-dependent thermal noise in the folded cavity. 相似文献
In this paper, we consider level-based preconditioning, which is one of the basic approaches to incomplete factorization preconditioning
of iterative methods. It is well-known that while structure-based preconditioners can be very useful, excessive memory demands
can limit their usefulness. Here we present an improved strategy that considers the individual entries of the system matrix
and restricts small entries to contributing to fewer levels of fill than the largest entries. Using symmetric positive-definite
problems arising from a wide range of practical applications, we show that the use of variable levels of fill can yield incomplete
Cholesky factorization preconditioners that are more efficient than those resulting from the standard level-based approach.
The concept of level-based preconditioning, which is based on the structural properties of the system matrix, is then transferred
to the numerical incomplete decomposition. In particular, the structure of the incomplete factorization determined in the
symbolic factorization phase is explicitly used in the numerical factorization phase. Further numerical results demonstrate
that our level-based approach can lead to much sparser but efficient incomplete factorization preconditioners. 相似文献
In this paper, we propose non-model-based strategies for locally stable convergence to Nash equilibrium in quadratic noncooperative games where acquisition of information (of two different types) incurs delays. Two sets of results are introduced: (a) one, which we call cooperative scenario, where each player employs the knowledge of the functional form of his payoff and knowledge of other players’ actions, but with delays; and (b) the second one, which we term the noncooperative scenario, where the players have access only to their own payoff values, again with delay. Both approaches are based on the extremum seeking perspective, which has previously been reported for real-time optimization problems by exploring sinusoidal excitation signals to estimate the Gradient (first derivative) and Hessian (second derivative) of unknown quadratic functions. In order to compensate distinct delays in the inputs of the players, we have employed predictor feedback. We apply a small-gain analysis as well as averaging theory in infinite dimensions, due to the infinite-dimensional state of the time delays, in order to obtain local convergence results for the unknown quadratic payoffs to a small neighborhood of the Nash equilibrium. We quantify the size of these residual sets and corroborate the theoretical results numerically on an example of a two-player game with delays.
The Lagrange theory of particle motion in the noninertial systems is applied to the Foucault pendulum, isosceles triangle
pendulum and the general triangle pendulum swinging on the rotating Earth. As an analogue, planet orbiting in the rotating
galaxy is considered as the giant galactic gyroscope. The Lorentz equation and the Bargmann-Michel-Telegdi equations are generalized
for the rotation system. The knowledge of these equations is inevitable for the construction of LHC where each orbital proton
“feels” the Coriolis force caused by the rotation of the Earth. 相似文献
Geometries, excitation energies, dipole moments and dipole polarisability tensor components of the ground and four lowest excited states 3B1, 1B1, 3A2, 1A2 of the H2O and H2S molecules were calculated at the CASSCF, CASPT2, CCSD and CCSD(T) level of approximation. Vertical excitation and equilibrium transition energies of these states, having the Rydberg character, are reported too. Properties of both molecules in the ground and in low lying excited states are compared and discussed from the point of view of their molecular electronic structure. Upon excitation we observe dramatic changes of dipole moments and polarisabilities with respect to the ground state. We stress the change of the polarity of H2O in all excited states accompanied by the enhancement of the dipole polarisability by an order of magnitude. Large, even if less pronounced, are changes of electric properties of H2S in its excited states. Dipole moments and dipole polarisabilities of 3B1, 1B1 states of H2S and H2O behave quite analogously in comparison to their respective ground state. The general pattern of properties for both molecules in their 3A2 and 1A2 excited states is more different due to a pronounced participation of the sulphur d-orbitals in these states of the H2S molecule. 相似文献
Textile blood vessels with a length of 30 cm were coated with amorphous diamond-like carbon (DLC) layers with thicknesses
up to 200 nm. The layers were created by pulsed laser deposition in vacuum or argon ambient. The percentage of sp3 carbon was evaluated using X-ray photoelectron spectroscopy, X-ray excited Auger electron spectroscopy and Raman spectroscopy.
Depending on the deposition conditions the sp3 content varied from ∼40% to 60%. The adhesion of the DLC layers to the textile vessels was checked. The preliminary biocompatibility
results from in vivo tests with sheep are also given. 相似文献