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1.
For a real measure with variation V(x) satisfying the estimate V(x) ≤ c 0 exp(Cx) and for the Laplace transform holomorphic in the disk {¦ -C¦ ≤ C} and having at least one pole of order m, we obtain lower bounds for the positive and negative parts of the measure V ± (x) > cx m , x > x 0. We establish lower bounds for V +- (x) on “short” intervals. Applications to number theory of the results obtained are considered. 相似文献
2.
The present study is aimed at expanding flexibility and application area of nonlinear acoustic modulation (NAM-) technique by combining the benefits of noncontact ultrasound excitation (remote locating and imaging of defects) with sensitivity of nonlinear methods in a new air-coupled NAM-version. A pair of focused air-coupled transducers was used to generate and receive (high-frequency) longitudinal or flexural waves in plate-like samples. Low-frequency (LF-) vibrations were excited with a shaker or a loudspeaker. Temporal and spectral analysis of the output signal revealed an extremely efficient nonlinear amplitude modulation and multiple frequency side-bands for sound transmission and flexural wave propagation through cracked defects. On the contrary, a negligible modulation was observed for large and medium scale inclusions and material inhomogeneities (linear defects). A new subharmonic mode of the NAM was observed at high excitation levels. It was also shown for the first time that nonlinear vibrations of cracks resulted in radiation of a very high-order harmonics (well above 100) of the driving excitation in air that enabled imaging of cracks remotely by registration their highly nonlinear "acoustic emission" with air-coupled transducers. 相似文献
3.
We consider the method for constrained convex optimization in a Hilbert space, consisting of a step in the direction opposite to an
k
-subgradient of the objective at a current iterate, followed by an orthogonal projection onto the feasible set. The normalized stepsizes
k
are exogenously given, satisfying
k=0
k = ,
k=0
k
2
< , and
k is chosen so that
k k for some > 0. We prove that the sequence generated in this way is weakly convergent to a minimizer if the problem has solutions, and is unbounded otherwise. Among the features of our convergence analysis, we mention that it covers the nonsmooth case, in the sense that we make no assumption of differentiability off, and much less of Lipschitz continuity of its gradient. Also, we prove weak convergence of the whole sequence, rather than just boundedness of the sequence and optimality of its weak accumulation points, thus improving over all previously known convergence results. We present also convergence rate results. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.Research of this author was partially supported by CNPq grant nos. 301280/86 and 300734/95-6. 相似文献
4.
A. A. Babin D. V. Kartashov A. M. Kiselev V. V. Lozhkarev A. M. Sergeev A. A. Solodov A. N. Stepanov 《JETP Letters》2002,76(9):548-552
The propagation of an intense (I≤106 W/cm2) femtosecond laser radiation with a duration of ~100 fs through gas-filled dielectric capillaries was studied. The radiation with a power up to 0.2 TW propagates along the paths up to 20 cm with a transmission efficiency of ~45%. The beam transverse structure at the output is close to the capillary fundamental mode under gas-ionization conditions. The transformation of pulse spectrum was studied as a function of input intensity. It is demonstrated experimentally that the pulse is compressed to a duration of ~30 fs due to the compensation of ionization-induced self-phase modulation in a linear dispersive element at the capillary output. 相似文献
5.
All nine elastic moduli of an orthotropic composite material, namely, polypropylene reinforced with glass fiber, are determined from the measured values of the bulk acoustic wave velocities along specific directions in the planes of symmetry of the material. These data are used to calculate the angular dependences of phase velocities, polarization vectors, and directions of ray velocities of bulk waves in the composite. It is demonstrated that the difference in the velocities of shear waves polarized along and across the glass fiber gives rise to an acoustic birefringence and can lead to an elliptical polarization of waves. The measurement of the phase velocities of shear waves as functions of the wave polarization is suggested as a method for the determination of the fiber orientation in a composite material. 相似文献
6.
Doz. Kand. Techn. Nauk. A. P. Solodov Dr.-Ing. D. Gorenflo 《Heat and Mass Transfer》1976,9(3):151-158
Zusammenfassung Experimentelle Ergebnisse zum überkritischen Wärmeübergang weisen für den Zustandsbereich nahe dem kritischen Punkt zum Teil große Abweichungen von der für unterkritische Fluide bekannten Abhängigkeit des Wärmeübergangskoeffizienten von der Wärmestromdichte auf. Am Beispiel des Kältemittels RC318 (C4F8) wird gezeigt, daß auch diese Ergebnisse mit den bekannten Beziehungen zwischen der Nußelt-, der Grashof- und der Prandtl-Zahl beschrieben werden können, wenn der thermische Ausdehnungskoeffizient und die spezifische Wärme in Gr bzw. Pr durch Differenzenquotienten ersetzt und zwei zusätzliche Parameter zur Beschreibung der Dichteänderung innerhalb der beheizten Fluidzone eingeführt werden. Da ein Teil der in den Kennzahlen benötigten Stoffwerte von RC318 im interessierenden Zustandsbereich nicht bekannt ist, werden die fehlenden Stoffwerte mit Hilfe des allgemeinen Korrespondenzprinzips berechnet.
Formelzeichen F Korrekturfaktor - R individuelle Gaskonstante - T Temperatur - Z Realfaktor - Gr, Nu, Pr Kennzahlen - a Temperaturleitzahl - cv, Cp spezifische Wärme - d Rohrdurchmesser - g Erdbeschleunigung - h spezifische Enthalpie - m Molekülmasse - p Druck - q Wärmestromdichte - u innere Energie - v spezifisches Volumen - Wärmeübergangskoeffizient - k Riedel-Parameter - thermischer Ausdehnungskoeffizient - Realanteil - Differenz zwischen einer Zustandsgröße des Fluids an der Heizwand und außerhalb der beheizten Zone - Asymmetrieparameter - Viskosität, dynamische - Wärmeleitzahl - Viskosität, kinematische - Dichte Indizes-hochgestellt normierte Größe - * auf den Wert am kritischen Punkt normierte Größe - 0 im Zustand des idealen Gases Indizes-tiefgestellt B, + Bezugswert - f Fluid außerhalb der beheizten Zone - k am kritischen Punkt - W an der Wand Herrn Professor Dr.-Ing. H. Glaser, Stuttgart, zum 70. Geburtstag gewidmet.Die Autoren danken Herrn Prof. Dr. K. Bier für die unterstützung der Arbeit und für wertvolle Diskussionsbeiträge. 相似文献
Calculation of free convective heat transfer near the critical state
For certain conditions free convective heat transfer from horizontal tubes to fluids near the critical state differs widely from the well-known dependency of heat transfer coefficient from heat flux. It is shown that experiments with refrigerant RC318 (C4F8) even for these conditions can be described by one of the often applied relationships between Nusselt and Rayleigh numbers, if the special form of density variation within the heated region of the fluid is taken into account. Most of the thermophysical properties of RC318 being unknown near the critical state, thermodynamic similarity considerations are used to calculate these data.
Formelzeichen F Korrekturfaktor - R individuelle Gaskonstante - T Temperatur - Z Realfaktor - Gr, Nu, Pr Kennzahlen - a Temperaturleitzahl - cv, Cp spezifische Wärme - d Rohrdurchmesser - g Erdbeschleunigung - h spezifische Enthalpie - m Molekülmasse - p Druck - q Wärmestromdichte - u innere Energie - v spezifisches Volumen - Wärmeübergangskoeffizient - k Riedel-Parameter - thermischer Ausdehnungskoeffizient - Realanteil - Differenz zwischen einer Zustandsgröße des Fluids an der Heizwand und außerhalb der beheizten Zone - Asymmetrieparameter - Viskosität, dynamische - Wärmeleitzahl - Viskosität, kinematische - Dichte Indizes-hochgestellt normierte Größe - * auf den Wert am kritischen Punkt normierte Größe - 0 im Zustand des idealen Gases Indizes-tiefgestellt B, + Bezugswert - f Fluid außerhalb der beheizten Zone - k am kritischen Punkt - W an der Wand Herrn Professor Dr.-Ing. H. Glaser, Stuttgart, zum 70. Geburtstag gewidmet.Die Autoren danken Herrn Prof. Dr. K. Bier für die unterstützung der Arbeit und für wertvolle Diskussionsbeiträge. 相似文献
7.
A. A. Solodov T. M. Petrova Yu. N. Ponomarev A. M. Solodov E. A. Glazkova 《Molecular physics》2017,115(14):1708-1712
The absorption spectra of CO and CO2 confined in nanopores of SiO2/Al2O3 xerogel have been measured using a Bruker IFS-125 HR Fourier spectrometer. Dependences of the half-width values on rotational quantum numbers and the line shift mean values are studied and compared with the data available in literature. Possible causes which can affect the rotational dependences are discussed. 相似文献
8.
T. M. Petrova A. M. Solodov A. A. Solodov V. M. Deichuli V. I. Starikov 《Molecular physics》2018,116(10):1409-1420
The water vapour line broadening and shifting for 97 lines in the ν1 + ν2 + ν3 band induced by hydrogen pressure are measured with Bruker IFS 125 HR FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm?1 and in a wide pressure range of H2. The calculations of the broadening γ and shift δ coefficients were performed in the semi-classical method framework with use of an effective vibrationally depended interaction potential. Two potential parameters were optimised to improve the quality of calculations. Good agreements with measured broadening coefficients were achieved. The comparison of calculated broadening coefficients γ with the previous measurements is discussed. The analytical expressions that reproduce these coefficients for rotational, ν2, ν1, and ν3 vibrational bands are presented. 相似文献
9.
Nonlinear acoustic approach to material characterisation of polymers and composites in tensile tests
The paper reports on experimental study of elastic nonlinearity of polymers and glass fibre-reinforced (GFR-) composites in a wide range of tensile stress applied (up to a fracture limit). Focused slanted transmission mode (FSTM) of air-coupled ultrasound is adapted for remote generation and detection of flexural waves in the samples of plastics. Local noncontact measurements of flexural wave velocity as a function of static strain are used to calculate the second-order nonlinearity parameters beta2 and study their behaviour through a loading cycle. Molecular untangling and crazing phenomena are identified, respectively, with maxima of positive and negative beta2 in thermoplastics. In composites, mechanics of fibre-matrix interaction is considered for brittle and plastic fractures. Hysteresis in velocity variation during loading-unloading cycle is used as an indicator of residual defect accumulation. 相似文献
10.
We consider the class of quadratically-constrained quadratic-programming methods in the framework extended from optimization
to more general variational problems. Previously, in the optimization case, Anitescu (SIAM J. Optim. 12, 949–978, 2002) showed superlinear convergence of the primal sequence under the Mangasarian-Fromovitz constraint qualification and the quadratic
growth condition. Quadratic convergence of the primal-dual sequence was established by Fukushima, Luo and Tseng (SIAM J. Optim.
13, 1098–1119, 2003) under the assumption of convexity, the Slater constraint qualification, and a strong second-order sufficient condition.
We obtain a new local convergence result, which complements the above (it is neither stronger nor weaker): we prove primal-dual
quadratic convergence under the linear independence constraint qualification, strict complementarity, and a second-order sufficiency
condition. Additionally, our results apply to variational problems beyond the optimization case. Finally, we provide a necessary
and sufficient condition for superlinear convergence of the primal sequence under a Dennis-Moré type condition.
Research of the second author is partially supported by CNPq Grants 300734/95-6 and 471780/2003-0, by PRONEX–Optimization,
and by FAPERJ. 相似文献