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81.
Qin L Hagel K Wada R Natowitz JB Shlomo S Bonasera A Röpke G Typel S Chen Z Huang M Wang J Zheng H Kowalski S Barbui M Rodrigues MR Schmidt K Fabris D Lunardon M Moretto S Nebbia G Pesente S Rizzi V Viesti G Cinausero M Prete G Keutgen T El Masri Y Majka Z Ma YG 《Physical review letters》2012,108(17):172701
Clustering in low density nuclear matter has been investigated using the NIMROD multidetector at Texas A&M University. Thermal coalescence modes were employed to extract densities, ρ, and temperatures, T, for evolving systems formed in collisions of 47A MeV (40)Ar+(112)Sn, (124)Sn and (64)Zn+(112)Sn, (124)Sn. The yields of d, t, (3)He, and (4)He have been determined at ρ=0.002 to 0.03 nucleons/fm(3) and T=5 to 11 MeV. The experimentally derived equilibrium constants for α particle production are compared with those predicted by a number of astrophysical equations of state. The data provide important new constraints on the model calculations. 相似文献
82.
An analytic model termed the ‘integrated quasi-steady-state’ (IQSS) model for the comprehensive quantification of both linear and nonlinear regime laser-induced fluorescence (LIF) is presented. The IQSS model is optimized for the hydroxyl radical (OH), subject to nanosecond A2Σ+←X2Π(1,0) excitation at pressures close to atmospheric. The IQSS model is particularly relevant to experimental conditions where the LIF signal is both spectrally and temporally integrated, such as in planar laser-induced fluorescence experiments. The IQSS model is based around a quasi-steady-state solution to a four-level rate-equation approximation of the OH molecule; this quasi-steady-state solution is then integrated with a triangular functional form for both the spatial and temporal variations to produce an analytic solution. In order to accurately predict LIF in the nonlinear regime, it is shown that both the temporal and the spatial variations of the laser pulse—or ‘wings’ of the laser pulse—must be adequately accounted for in the LIF model formulation. The IQSS model is successfully verified against detailed numerical simulations for variations in the laser irradiance, quenching environment and temperature. Experimentally, the IQSS model is successfully validated by comparing the predicted and measured OH LIF vs. irradiance dependence in the product gases of a methane–air laminar flame. 相似文献
83.
Let p(n) denote the number of partitions of a positive integer n. In this paper we study the asymptotic growth of p(n) using the equidistribution of Galois orbits of Heegner points on the modular curve X
0(6). We obtain a new asymptotic formula for p(n) with an effective error term which is
O(n-(\frac12+d)){O(n^{-(\frac{1}{2}+\delta)})} for some δ > 0. We then use this asymptotic formula to sharpen the classical bounds of Hardy and Ramanujan, Rademacher, and Lehmer on
the error term in Rademacher’s exact formula for p(n). 相似文献
84.
In this paper we study the central values of L-functions associated to a large class of algebraic Hecke characters of imaginary quadratic fields. When these central values
are nonzero, the Bloch–Kato conjecture predicts an exact formula for the algebraic parts of the central values in terms of
periods and arithmetic data, most notably the Selmer groups corresponding to the Hecke characters. We investigate the nonvanishing
of these central values, and prove the p-part of the Bloch–Kato conjecture in these cases for primes p which split in K. 相似文献
85.
Quaranta Giuseppe Formica Giovanni Machado J. Tenreiro Lacarbonara Walter Masri Sami F. 《Nonlinear dynamics》2020,101(3):1583-1619
Nonlinear Dynamics - The outbreak of COVID-19 in Italy took place in Lombardia, a densely populated and highly industrialized northern region, and spread across the northern and central part of... 相似文献
86.
We establish an asymptotic formula with a power savings in the error term for traces of CM values of a family of Maass–Poincaré series which contains the modular j-function as a special case. By work of Borcherds (1998) [2], Zagier (2002) [31], and Bringmann and Ono (2007) [4], these traces are Fourier coefficients of half-integral weight weakly holomorphic modular forms and Maass forms. 相似文献
87.
Building on the basic idea behind the Restoring Force Method for the non-parametric identification of non-linear systems, a general procedure is presented for the direct identification of the state equation of complex non-linear systems. No information about the system mass is required, and only the applied excitation(s) and resulting acceleration are needed to implement the procedure. Arbitrary non-linear phenomena spanning the range from polynomial non-linearities to the noisy Duffing-van der Pol oscillator (involving product-type non-linearities and multiple excitations) or hysteretic behavior such as the Bouc-Wen model can be handled without difficulty. In the case of polynomial-type non-linearities, the approach yields virtually exact results for sufficiently rich excitations. For other types of non-linearities, the approach yields the optimum (in least-squares sense) representation in non-parametric form of the dominant interaction forces induced by the motion of the system. Several examples involving synthetic data corresponding to a variety of highly non-linear phenomena are presented to demonstrate the utility as well as the range of validity of the proposed approach. 相似文献
88.
Measurements of mean velocity components, turbulent intensity, and Reynolds shear stress are presented in a turbulent lifted
H2/N2 jet flame as well as non-reacting air jet issuing into a vitiated co-flow by laser doppler velocimetry (LDV) technique. The
objectives of this paper are to obtain a velocity data base missing in the previous experiment data of the Dibble burner and
so provide initial and flow field data for evaluating the validity of various numerical codes describing the turbulent partially
premixed flames on this burner. It is found that the potential core is shortened due to the high ratio of jet density to co-flow
density in the non-reacting cases. However, the existence of flame suppressed turbulence in the upstream region of the jet
dominates the length of potential core in the reacting cases. At the centreline, the normalized axial velocities in the reacting
cases are higher than the non-reacting cases, and the relative turbulent intensities of the reacting flow are smaller than
in the non-reacting flow, where a self-preserving behaviour for the relative turbulent intensities exists at the downstream
region. The profiles of mean axial velocity in the lifted flame distribute between the non-reacting jet and non-premixed flame
both in the axial and radial distributions. The radial distributions of turbulent kinetic energy in the lifted flames exhibit
a change in distributions indicating the difference of stabilisation mechanisms of the two lifted flame. The experimental
results presented will guide the development of an improved modelling for such flames. 相似文献
89.
J. Pezoldt Ch. Zgheib V. Lebedev P. Masri O. Ambacher 《Superlattices and Microstructures》2006,40(4-6):612
Heteroepitaxially grown 3C-SiC and 2H-AlN layers on Ge modified Si(111) substrates were investigated by Fourier transform infrared spectroscopic ellipsometry. The obtained phonon frequencies increase with increasing Ge pre-deposition indicating a decrease of the residual stress in both wide band gap materials. Additionally, it is shown that infrared ellipsometry allows the analysis of the polytype content of the grown epitaxial layers. 相似文献
90.
Paul R. Medwell Assaad R. Masri Phuong X. Pham Bassam B. Dally Graham J. Nathan 《Experiments in fluids》2014,55(11):1-11
To study the behavior of thixotropic yield stress fluids, information at the local scale is required in order to determine precisely the yield point value, and the shear rate and stresses can be obtained all over the flow. This study focuses on the flow in a large shear cell of a Laponite suspension. In order to be able to construct a local rheogram for this suspension, two different methods issued from fluid mechanics and solid mechanics are used. Local velocities are determined with a PIV technique, and local stresses are determined with the photoelasticimetry technique. 相似文献