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Kämpfer, B.

doi:10.1002/1521-3889(200009)9:8<605::aid-andp605>3.0.co;2-6

Cited by 23 publications

(29 citation statements)

References 1 publication

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“…As predicted by the Standard Model of particle physics, before the QCD transition, g * (τ q ) = 51.25 at the time τ q ; and after the QCD transition, it becomes g * (τ x ) = 17.25 at the time τ x [45,46]. Applying Eq.…”

Section: Presented Inmentioning

confidence: 87%

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Modifications by the QCD transition ande+e−annihilation of the analytic spectrum of relic gravitational waves in the accelerating universe

et al. 2008

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As predicted by quantum chromodynamics(QCD), around T ∼ 190 MeV in the early universe, the QCD transition occurs during which the quarks are combined into the massive hadrons.This process reduces the effective relativistic degree of freedom, and causes a change in the expansion behavior of the universe. Similarly, the e + e − annihilation occurred around T ∼ 0.5 Mev has the same kind of effect. Besides, the dark energy also drives the present stage accelerating expansion. We study these combined effects on the relic gravitational waves (RGWs). In our treatment, the QCD transition and the e + e − annihilation, each is respectively represented by a short period of expansion inserted into the radiation era. Incorporating these effects, the equation of RGWs is analytically solved for a spatially flat universe, evolving from the inflation up to the current acceleration, and the spectrum of RGWs is obtained, covering the whole range of frequency > 10 −19 Hz. It is found that the QCD transition causes a reduction of the amplitude of RGWs by ∼ 20% in the range > 10 −9 Hz, and the e + e − annihilation causes a reduction ∼ 10% in the range > 10 −12 Hz. In the presence of the dark energy, the combination of the QCD transition and the e + e − annihilation, causes a larger reduction of the amplitude by ∼ 30% for the range > 10 −9 Hz, which covers the bands of operation of LIGO and LISA. By analysis, it is shown that RGWs will be difficult to detect by the present LIGO, but can be tested by LISA for certain inflationary models.

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Section: Presented Inmentioning

confidence: 87%

“…Ref. [45] gives a value of the ratio t x /t q ∼ 2; Ref. [46] estimated the typical duration of QCD transition to be the order of ∼ 0.1t q , i.e., t x /t q ∼ 1.1.…”

Section: Presented Inmentioning

confidence: 99%

Modifications by the QCD transition ande+e−annihilation of the analytic spectrum of relic gravitational waves in the accelerating universe

et al. 2008

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“…14,15 It has also been applied in other fields of physics, such as crystallization kinetics of lipids 16 or polymers, 17 the analysis of depositions on surface science, 18 the evolution of ecological systems, 19 and even in cosmology. 20 …”

Section: Solid State Isothermal Reactionsmentioning

confidence: 99%

“…ÀQc RT : (20) At this point, t m is still unknown. However, as the strain rate is minimum at t m , deriving again Eq.…”

Section: B Strain Rates As a Function Of Microstructural Parametersmentioning

confidence: 99%

Primary and secondary creep in aluminum alloys as a solid state transformation

Fernández

Bruno

González-Doncel

2016

Journal of Applied Physics

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Despite the massive literature and the efforts devoted to understand the creep behavior of aluminum alloys, a full description of this phenomenon on the basis of microstructural parameters and experimental conditions is, at present, still missing. The analysis of creep is typically carried out in terms of the so-called steady or secondary creep regime. The present work offers an alternative view of the creep behavior based on the Orowan dislocation dynamics. Our approach considers primary and secondary creep together as solid state isothermal transformations, similar to recrystallization or precipitation phenomena. In this frame, it is shown that the Johnson-Mehl-AvramiKolmogorov equation, typically used to analyze these transformations, can also be employed to explain creep deformation. The description is fully compatible with present (empirical) models of steady state creep. We used creep curves of commercially pure Al and ingot AA6061 alloy at different temperatures and stresses to validate the proposed model. Published by AIP Publishing.[http://dx.doi.org/10.1063/1.4961524] I. CREEP OF METALSCreep of metals is a key topic for different industries such as energy, transport, or chemical. The creep behavior of pure metals and alloys has been extensively investigated in the past. This behavior is usually described through the accumulated plastic deformation e (t) as a function of time t under given conditions of applied stress, r, and temperature, T. Three regions are typically distinguished, namely, a primary creep region (where € eðtÞ < 0Þ; a secondary regime, also called steady state (where € eðtÞ ¼ 0); and a tertiary region (where € eðtÞ > 0) before creep rupture occurs (double dot denotes second time derivative). Many authors, as Evans, 1 reduce the steady state regime to a single turning point from the primary to the tertiary regions in the creep curve. This is, then, called the minimum creep rate state. For simplicity, however, we will refer throughout this work to a steady state region. Most of the investigations aimed at correlating the creep behavior with microstructural parameters of the alloy under study restrict their analysis to the steady state regime, where the creep rate is independent of time, i.e., one can write _ e ¼ _ e ss ðr; TÞ (dot denotes first time derivative).

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“…In fact as shown in ref. [20], the sound speed near T c can become very small (e.g. even smaller than 0.2), whereby the time for attaining pressure equilibrium will become at least 10 −10 sec, which is much larger than the time taken to complete the bubble nucleation process in the region outside.…”

Section: Effect Of the Inhomogeneities On The Phase Transitionmentioning

confidence: 99%

Effect of pre-existing baryon inhomogeneities on the dynamics of quark-hadron transition

Sanyal

2003

Pramana - J Phys

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Baryon number inhomogeneities may be generated during the epoch when the baryon asymmetry of the universe is produced, e.g. at the electroweak phase transition. The regions with excess baryon number will have a lower temperature than the background temperature of the universe. Also the value of the quark hadron transition temperature T c will be different in these regions as compared to the background region. Since a first-order quark hadron transition is very susceptible to small changes in temperature, we investigate the effect of the presence of such baryonic lumps on the dynamics of quarkhadron transition. We find that the phase transition is delayed in these lumps for significant overdensities. Consequently, we argue that baryon concentration in these regions grows by the end of the transition. We briefly discuss some models which may give rise to such high overdensities at the onset of the quark-hadron transition.

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Cited by 23 publications

References 1 publication

Modifications by the QCD transition ande+e−annihilation of the analytic spectrum of relic gravitational waves in the accelerating universe

Modifications by the QCD transition ande+e−annihilation of the analytic spectrum of relic gravitational waves in the accelerating universe

Primary and secondary creep in aluminum alloys as a solid state transformation

Effect of pre-existing baryon inhomogeneities on the dynamics of quark-hadron transition

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