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111.
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114.
Vasile Dragan Aristide Halanay Vlad Ionescu 《Integral Equations and Operator Theory》1994,19(2):153-215
It is proved that for the discrete-time linear systems with time-varying coefficients the existence of a controller which simultaneously stabilizes and provides prescribed disturbance attenuation for the resultant closed-loop system, implies the existence of global solutions to several Kalman-Szegö-Popov-Yakubovich systems. It is also proved that this fact is equivalent to the existence of the positive semidefinite stabilizing solutions to corresponding game-theoretic Riccati equations. The family of all controllers with the above mentioned properties is constructed in terms of the solutions to the cited Kalman-Szegö-Popov-Yakubovich systems. The main tool is the generalized Popov-Yakubovich theory which is essentially developed in an operator-theoretic framework. 相似文献
115.
José Seade Mihai Tibăr Alberto Verjovsky 《Bulletin of the Brazilian Mathematical Society》2005,36(2):275-283
Using a geometric approach, we determine the relations between the local Euler obstruction Euf of a holomorphic function f and several generalizations of the Milnor number for functions on singular spaces.
*This work was partially supported by CNRS-CONACYT (12409) Cooperation Program. The first and third named authors partially
supported by CONACYT grant G36357-E and DGPA (UNAM) grant IN 101 401. 相似文献
116.
The P-V-T relations of high pressure polyethylene free of additives have been studied in a modified universal testing machine. These polymers show a rapid compression at the melting point of the crystalline phase. 相似文献
117.
Tudor Ionescu 《Linear algebra and its applications》1976,15(3):271-292
It will be shown that given any element X in a simple Lie algebra over C, there exists a Y ∈ such that the Lie algebra generated by X and Y is . The result is extended to the real semisimple Lie algebras. In some sense the main theorem of this paper can be regarded as an extension of Morozov-Jacobson theorem concerning three dimensional simple Lie algebras (see the remark at the end of Sec. 4). A new property of a special class of regular elements, known as the cyclic elements, is given. 相似文献
118.
D. V. Ionescu 《Acta Mathematica Hungarica》1967,18(3-4):283-295
Sans résumé
Présenté par
P. Turán 相似文献
119.
In real semialgebraic geometry it is common to represent a polynomial q which is positive on a region R as a weighted sum of squares. Serious obstructions arise when q is not strictly positive on the region R. Here we are concerned with noncommutative polynomials and obtaining a representation for them which is valid even when strict
positivity fails.
Specifically, we treat a ``symmetric' polynomial q(x, h) in noncommuting variables, {x1, . . . , } and {h1, . . . , } for which q(X,H) is positive semidefinite whenever
are tuples of selfadjoint matrices with ||Xj|| ≤ 1 but Hj unconstrained. The representation we obtain is a Gram representation in the variables h
where Pq is a symmetric matrix whose entries are noncommutative polynomials only in x and V is a ``vector' whose entries are polynomials in both x and h. We show that one can choose Pq such that the matrix Pq(X) is positive semidefinite for all ||Xj|| ≤ 1. The representation covers sum of square results ([Am. Math. (to appear); Linear Algebra Appl. 326 (2001), 193–203; Non commutative Sums of Squares, preprint]) when gx = 0. Also it allows for arbitrary degree in h, rather than degree two, in the main result of [Matrix Inequalities: A Symbolic Procedure to Determine Convexity Automatically
to appear IOET July 2003] when restricted to x-domains of the type ||Xj|| ≤ 1.
Partially supported by NSF, DARPA and Ford Motor Co.
Partially supported by NSF grant DMS-0140112
Partially supported by NSF grant DMS-0100367 相似文献
120.
Tao C Deselnicu M Fan H Mukarakate C Ionescu I Reid SA 《Physical chemistry chemical physics : PCCP》2006,8(6):707-713
To further investigate the Renner-Teller (RT) effect and barriers to linearity and dissociation in the simplest singlet carbene, we recorded fluorescence excitation spectra of bands involving the pure bending levels 2(n)(0) with n = 0-9 and the combination states 1(1)(0)2(n)(0) with n = 1-8 and 2(n)(0)3(1)(0) with n = 0-5 in the A(1)A'<-- X(1)A' system of CDF, in addition to some weak hot bands. The spectra were measured under jet-cooled conditions using a pulsed discharge source, and rotationally analyzed to yield precise values for the band origins and rotational constants; fluorescence lifetimes were also measured to probe for lifetime lengthening effects due to the RT interaction. The derived A state parameters are compared with previous results for CHF and with predictions of ab initio electronic structure theory. The approach to linearity in the A state is evidenced in a sharp increase in the A rotational constant with bending excitation, and a minimum in the vibrational intervals near 2(9). A fit of the vibrational intervals for the pure bending levels yields an A state barrier to linearity in good agreement both with that previously derived for CHF and ab initio predictions. From the spectra and lifetime measurements, the onset of extensive RT perturbations is found to occur at a higher energy than in CHF, consistent with the smaller A constant. 相似文献