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The observational constraint on constant-roll inflation

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Science China(Physics,Mechanics & Astronomy) 2018年第7期61卷 38-43页

作者： qing gao School of Physical Science and Technology Southwest University Chongqing 400715 China

We discuss the constant-roll inflation with constant ∈1 and constant η. By using the method of Bessel function approximation, the analytical expressions for the scalar and tensor power spectra, the scalar and tensor spectral tilts, and the tensor to scalar ratio are derived up to the first order of ∈1. The model with constant ∈2 is ruled out by the observations at the 3σ confidence level, and the model with constant η is consistent with the observations at the 1σ confidence level. The potential for the model with constant η is also obtained from the Hamilton-Jacobi equation. Although the observations constrain the constant-roll inflation to be the slow-roll inflation, the ns-r results from the constant-roll inflation are not the same as those from the slow-roll inflation even when η- 0.01.

关键词： constant-roll inflation cosmological perturbations cosmological constraints

Primordial black holes and secondary gravitational waves from chaotic infiation

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Science China(Physics,Mechanics & Astronomy) 2021年第8期64卷 7-14页

作者： qing gao School of Physical Science and Technology Southwest UniversityChongqing 400715China

Chaotic inflation is inconsistent with the observational constraint at 68% CL. Here, we show that the enhancement mechanism with a peak function in the noncanonical kinetic term not only helps the chaotic model V(φ) = V0φ^(1/3) satisfy the observational constraint at large scales but also enhances the primordial scalar power spectrum by seven orders of magnitude at small *** enhanced curvature perturbations can produce primordial black holes of different masses and secondary gravitational waves with different peak frequencies. We also show that the non-Gaussianities of curvature perturbations have little effect on the abundance of primordial black holes and energy density of the scalar-induced secondary gravitational waves.

关键词： chaotic infiation primordial black holes secondary gravitational waves

Reconstruction of constant slow-roll inflation

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Science China(Physics,Mechanics & Astronomy) 2017年第9期60卷 17-21页

作者： qing gao School of Physical Science and Technology Southwest University

Using the relations between the slow-roll parameters and the power spectra for the single field slow-roll inflation, we derive the scalar spectral tilt n, and the tensor to scalar ratio r for the constant slow-roll inflation, and obtain the constraint on the slow-roll parameter ηfrom the Planck 2015 results. The inflationary potential for the constant slow-roll inflation is then reconstructed in the framework of both general relativity and the scalar-tensor theory of gravity, and compared with the recently reconstructed E model potential. In the strong coupling limit, we show that the η attractor is reached.

关键词： constant slow-roll inflation reconstruction scalar.tensor theories of gravity

Laws of the Iterated Logarithm for Locally Square Integrable Martingales

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Acta Mathematica Sinica,English Series 2009年第2期25卷 209-222页

作者： Fu qing gao School of Mathematics and Statistics Wuhan University Wuhan 430072 P. R. China

Three types of laws of the iterated logarithm （LIL） for locally square integrable martingales with continuous parameter are considered by a discretization approach. By this approach, a lower bound of LIL and a numbe... 详细信息

关键词： locally square integrable martingales law of the iterated logarithm

Moderate Deviations for Random Sums of Heavy-Tailed Random Variables

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Acta Mathematica Sinica,English Series 2007年第8期23卷 1527-1536页

作者： Fu qing gao School of Mathematics and Statistics Wuhan University Wuhan 430072 P. R. China

Let {Xn;n≥ 1} be a sequence of independent non-negative random variables with common distribution function F having extended regularly varying tail and finite mean μ = E（X1） and let {N（t）; t ≥0} be a random process taking non-negative integer values with finite mean λ（t） = E（N（t）） and independent of {Xn; n ≥1}. In this paper, asymptotic expressions of P（（X1 ＋… ＋XN（t）） -λ（t）μ 〉 x） uniformly for x ∈[γb（t）, ∞） are obtained, where γ〉 0 and b（t） can be taken to be a positive function with limt→∞ b（t）/λ（t） = 0.

关键词： large deviations moderate deviations extended regular variation Poisson process

Laws of the Iterated Logarithm for High-Dimensional Wiener Sausage

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Acta Mathematica Sinica,English Series 2011年第8期27卷 1599-1610页

作者： Yan qing WANG Fu qing gao School of Mathematics and Statistics Wuhan University Wuhan 430072 P. R. China

Let {β（s）,s ≥ O} be the standard Brownian motion in R^d with d ≥ 4 and let ｜Wr（t）｜ be the volume of the Wiener sausage associated with {β（s）, s ≥ O} observed until time t. Prom the central limit theorem of Wiener sausage, we know that when d ≥ 4 the limit distribution is normal. In this paper, we study the laws of the iterated logarithm for ｜Wr（t）｜ - e｜Wr（t）｜ in this case.

关键词： Wiener sausage Kolmogorov's law of the iterated logarithm Chung's law of the iterated logarithm

A damage-coupled multi-axial time-dependent low cycle fatigue failure model for SS304 stainless steel at high temperature

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Acta Metallurgica Sinica(English Letters) 2011年第2期24卷 169-174页

作者： Yujie LIU qing gao Guozheng KANG School of Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

Based on the time-dependent strain cyclic characteristics and fatigue behaviors of SS304 stainless steel under multi-axial cyclic loading at 700 ？ C, and in the frame of unified visoco-plastic cyclic constitutive model and continuum damage mechanics theory, the damage-coupled multi-axial time-dependent constitutive model and fatigue failure model were proposed. In the model, the evolution equation of damage was introduced in and the time-dependent effects, e.g. holding time, loading rate, were taken into account. The model was applied to the simulation of whole-life cyclic deformation behaviors and prediction of LCF life for SS304 stainless steel in multiaxial time-dependent low cycle fatigue tests. It is shown that the simulated results agree well with experimental ones.

关键词： SS304 stainless steel Constitutive model Low cycle fatigue Failure model Damage-coupled High temperature

Simulation and Analysis of Dual-Evaporator Refrigeration System for Electric Vehicles

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Automotive Innovation 2020年第4期3卷 347-355页

作者： Ming Shen qing gao State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025China College of Automotive Engineering Jilin UniversityChangchun 130025China Department of Thermal Engineering Jilin UniveristyChangchun 130022China

Thermal management system is a crucial part in electric vehicles to ensure battery safety and driving comfort.A refrigerant-based thermal management system of electric vehicles with two evaporators connected in series(series system)or in parallel(parallel system)is *** performances of the two systems are investigated and *** results reveal that the optimal refrigerant charge is approximately 600 ***,there is no correlation between the optimal refrigerant charge,and in the arrangement of heat sinks or the heat *** the optimal refrigerant charge,the coefficient of perfor-mance of the series system ranges from 3.47 to *** coefficient of performance of the parallel system ranges from 3.40 to 4.59,which is lower than that of the series ***,the series system has higher exergy efficiency and better cooling *** heat source(cabin)with a small thermal mass placed in the rear evaporator of the series system can weaken the lag of its cooling *** additional serial evaporator is an alternative solution to the dual-evaporator thermal management system of electric vehicles.

关键词： Lithium-ion battery Thermal management Dual evaporators Simulation analysis

Some embedding theorems for W～(1,p)(Ω, H～n)

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Applied Mathematics(A Journal of Chinese Universities) 2010年第1期25卷 85-92页

作者： JIA gao ZHANG Guo-qing College of Science University of Shanghai for Science and Technology Shanghai 200090 China

For the maps on the Heisenberg group target, we prove a Poincare type inequality. Applying this Poincare type inequality, we obtain the corresponding versions of Sobolev and Rellich embedding theorems.

关键词： Heisenberg group HSlder continuity embedding theorem.