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91.
This paper studies the existence of bounded solutions of a forced non-linear differential equation of arbitrary order. Necessary and sufficient conditions for the existence of such solutions are obtained. These results are inspired by classical results on the periodic problem, both in the resonant and non-resonant cases.
92.
José Luis Sánchez Bote Antonio Pedrero González Juan José Gómez Alfageme 《Applied Acoustics》2012,73(9):977-985
This paper presents a new verification procedure for sound source coverage according to ISO 140–5 requirements. The ISO 140–5 standard applies to the measurement of façade insulation and requires a sound source able to achieve a sufficiently uniform sound field in free field conditions on the façade under study. The proposed method involves the electroacoustic characterisation of the sound source in laboratory free field conditions (anechoic room) and the subsequent prediction by computer simulation of the sound free field radiated on a rectangular surface equal in size to the façade being measured. The loudspeaker is characterised in an anechoic room under laboratory controlled conditions, carefully measuring directivity, and then a computer model is designed to calculate the acoustic free field coverage for different loudspeaker positions and façade sizes. For each sound source position, the method provides the maximum direct acoustic level differences on a façade specimen and therefore determines whether the loudspeaker verifies the maximum allowed level difference of 5 dB (or 10 dB for façade dimensions greater than 5 m) required by the ISO standard. Additionally, the maximum horizontal dimension of the façade meeting the standard is calculated and provided for each sound source position, both with the 5 dB and 10 dB criteria. In the last section of the paper, the proposed procedure is compared with another method used by the authors in the past to achieve the same purpose: in situ outdoor measurements attempting to recreate free field conditions. From this comparison, it is concluded that the proposed method is able to reproduce the actual measurements with high accuracy, for example, the ground reflection effect, at least at low frequencies, which is difficult to avoid in the outdoor measurement method, and it is fully eliminated with the proposed method to achieve the free field requisite. 相似文献
93.
Mercedes Landete Juan Francisco Monge Antonio M. Rodríguez-Chía 《Annals of Operations Research》2013,207(1):137-160
An alternative formulation for the set packing problem in a higher dimension is presented. The addition of a new family of binary variables allows us to find new valid inequalities, some of which are shown to be facets of the polytope in the higher dimension. We also consider the Winner Determination Problem, which is equivalent to the set packing problem and whose special structure allows us to easily implement these valid inequalities in a very easy way. The computational experiments illustrate the performance of the valid inequalities and obtain good results. 相似文献
94.
Antonio Lanteri Roberto Muñ oz 《Transactions of the American Mathematical Society》2006,358(12):5565-5585
Let be a smooth complex projective variety, let be an ample and spanned line bundle on , defining a morphism and let be its discriminant locus, the variety parameterizing the singular elements of . We present two bounds on the dimension of and its main component relying on the geometry of . Classification results for triplets reaching the bounds as well as significant examples are provided.
95.
José María Gómez-Ros Roberto Bedogni Montserrat Moraleda Ana Romero Antonio Delgado Adolfo Esposito 《Radiation measurements》2010,45(10):1220-1223
This communication describes a new neutron spectrometer consisting of pairs of 7Li and 6Li based thermoluminescent dosemeters (MCP-6, MCP-7) located at selected positions within a single moderating polyethylene sphere. The spatial arrangement of the dosemeters has been designed using the MCNPX Monte Carlo code to calculate the response matrix in order to obtain a nearly isotropic response for neutrons in the energy range up to 20 MeV. A partial validation of the calculated response matrix has been performed with the calibrated 241Am–Be neutron source at the INFN–LNF Laboratory, using the shadow cone technique. 相似文献
96.
Daniele Di Gioacchino Augusto Marcelli Antonio Bianconi 《Journal of Physics and Chemistry of Solids》2010,71(8):1046-1052
In this contribution we present the analysis of the third harmonic susceptibility data of the new superconductor NdFeAs1−0.14F0.14. ‘Cole-Cole’ polar plots respect to the magnetic frequency of the exciting field are presented and discussed. Data show that NdFeAs1−0.14F0.14 exhibit a ‘bulk pinning’ with a 3D flux dynamic character. A comparison of the responses of high Tc materials and an evaluation of theoretical critical states is also presented. 相似文献
97.
Let A be a unital C*-algebra with non-zero socle (soc(A)). We introduce the essential conorm of an element a in A (denoted by γ
e
(a)), as the conorm of the element π(a), where π denotes the canonical projection of A onto . It is established that for every von Neumann regular element , γ
e
(a) = max . We characterize the continuity points of the conorm and essential conorm for extremally rich C*-algebras. Some formulae for the distance from zero to the generalized spectrum and Atkinson spectrum are also obtained.
Authors partially supported by I+D MEC projects no. MTM2005-02541 and MTM2007-65959, and Junta de Andalucía grants FQM0199
and FQM1215. 相似文献
98.
Antonio J. Durn 《Journal of Approximation Theory》2009,161(1):88-113
The method developed in [A.J. Durán, F.A. Grünbaum, Orthogonal matrix polynomials satisfying second order differential equations, Int. Math. Res. Not. 10 (2004) 461–484] led us to consider matrix polynomials that are orthogonal with respect to weight matrices W(t) of the form , , and (1−t)α(1+t)βT(t)T*(t), with T satisfying T′=(2Bt+A)T, T(0)=I, T′=(A+B/t)T, T(1)=I, and T′(t)=(−A/(1−t)+B/(1+t))T, T(0)=I, respectively. Here A and B are in general two non-commuting matrices. We are interested in sequences of orthogonal polynomials (Pn)n which also satisfy a second order differential equation with differential coefficients that are matrix polynomials F2, F1 and F0 (independent of n) of degrees not bigger than 2, 1 and 0 respectively. To proceed further and find situations where these second order differential equations hold, we only dealt with the case when one of the matrices A or B vanishes.The purpose of this paper is to show a method which allows us to deal with the case when A, B and F0 are simultaneously triangularizable (but without making any commutativity assumption). 相似文献
99.
Balsells JM Jurado-Navas A Paris JF Castillo-Vázquez M Puerta-Notario A 《Optics letters》2012,37(4):719-721
In this paper, the performance of the variable weight multiple pulse-position modulation (MPPM) coding technique in an atmospheric optical communication environment under gamma-gamma optical scintillation is analyzed, proposing a closed-form expression for the average bit error rate (BER). This study is based on a hyperexponential fitting of the conditional BER in absence of turbulence fluctuations, leading to closed-form expressions that characterize the behavior of this nonlinear coding scheme. Finally, conditional and average BER expressions proposed here are corroborated with Monte Carlo simulations results. 相似文献
100.