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1.
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
2.
3.
Systems with constraints, the masses in which move only along guides, can execute strongly nonlinear vibrations. This means
that nonlinear phenomena manifest themselves at arbitrary small deviations from equilibrium. The form of vibrations of a single
mass is described by elliptical Jacobi functions. The spectrum of these vibrations is found. With an increase in amplitude,
the period of vibrations decreases. We deduce equations of strongly nonlinear vibrations of a chain of connected masses. In
the continuum limit, we obtain a new nonlinear equation in partial derivatives. We devise transformation of variables leading
to linearization of this equation. We implemented a factorization procedure that decreases the order of the equation in partial
derivatives from second to first. Exact solutions to the first-order equation describe the slow evolution of the displacement
profile in a distributed system. In the absence of preliminary tension of elastic elements in the continued model, traveling
waves cannot be achieved; however, time-oscillating solutions like standing waves are possible. We obtain an equation for
a field of strongly nonlinear deformations. Its exact solution describes periodic movement in time and space. As well, the
period of time oscillations decreases with an increase in amplitude, and the spatial period, in contrast, increases. The product
of the vibration frequency multiplied by the spatial period is a constant that depends on the deformation energy. We propose
a scheme of the mechanical system producing strongly nonlinear torsional vibrations. We experimentally measured the period
of torsional vibrations of a single disc. We show that with an increase in amplitude in the process of vibration attenuation,
an increase in the period occurs, which agrees with calculations. We measure the shapes of nonlinear vibrations of a chain
of connected discs. A strongly nonlinear behavior of the chain is observed. 相似文献
4.
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
5.
We propose a modification of the classical extragradient and proximal point algorithms for finding a zero of a maximal monotone operator in a Hilbert space. At each iteration of the method, an approximate extragradient-type step is performed using information obtained from an approximate solution of a proximal point subproblem. The algorithm is of a hybrid type, as it combines steps of the extragradient and proximal methods. Furthermore, the algorithm uses elements in the enlargement (proposed by Burachik, Iusem and Svaiter) of the operator defining the problem. One of the important features of our approach is that it allows significant relaxation of tolerance requirements imposed on the solution of proximal point subproblems. This yields a more practical proximal-algorithm-based framework. Weak global convergence and local linear rate of convergence are established under suitable assumptions. It is further demonstrated that the modified forward-backward splitting algorithm of Tseng falls within the presented general framework. 相似文献
6.
V. L. Ivanov R. R. Akhmetshin A. N. Amirkhanov A. V. Anisenkov V. M. Aulchenko V. S. Banzarov N. S. Bashtovoy D. E. Berkaev A. V. Bragin S. I. Eidelman D. A. Epifanov L. B. Epshteyn A. L. Erofeev G. V. Fedotovich S. E. Gayazov A. A. Grebenuk D. N. Grigoriev E. M. Gromov F. V. Ignatov S. V. Karpov V. F. Kazanin B. I. Khazin I. A. Koop O. A. Kovalenko A. N. Kozyrev E. A. Kozyrev P. P. Krokovny A. E. Kuzmenko A. S. Kuzmin I. B. Logashenko P. A. Lukin K. Yu. Mikhailov V. S. Okhapkin Yu. N. Pestov E. A. Perevedentsev A. S. Popov G. P. Razuvaev Yu. A. Rogovsky A. L. Romanov A. A. Ruban N. M. Ryskulov A. E. Ryzhenenkov V. E. Shebalin D. N. Shemyakin B. A. Shwartz D. B. Shwartz A. L. Sibidanov Yu. M. Shatunov P. Yu. Shatunov E. P. Solodov V. M. Titov A. A. Talyshev A. I. Vorobiov Yu. V. Yudin 《Physics of Atomic Nuclei》2016,79(2):251-259
We report preliminary results on the cross section of the process e+e? → φ(1020)η measured at 30 center-of-mass energy points in the range from 1.59 up to 2.0 GeV. Data analysis is based on the integrated luminosity of 22 pb?1 collected with the CMD-3 detector in 2011–2012. The obtained cross section agrees with the BaBar measurement and has better statistical accuracy. 相似文献
7.
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
8.
The coefficients of the water vapor line shifts induced by the pressure of oxygen, nitrogen, and argon are measured and calculated in the spectral range from 5000 to 5600 cm?1. The experimental data are obtained from the analysis of the absorption spectra of H2O-O2, H2O-N2, and H2O-Ar mixtures measured on a Fourier spectrometer with a resolution of 0.007 cm?1 in a wide pressure range of buffer gases at room temperature for an optical path length of 84.05 m. The calculations are performed according to the Anderson impact theory of broadening with the use of only one adjustable parameter—the effective mean dipole polarizability of the upper vibrational state. The shifts of one and the same lines induced by the pressure of different buffer gases are compared; the role played by different terms of the intermolecular potential in the formation of the shifts is analyzed. 相似文献
9.
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
10.
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