共查询到20条相似文献,搜索用时 117 毫秒
1.
L. Pereira A. Morozov M. M. Fraga T. Heindl R. Krücken J. Wieser A. Ulrich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(3):325-334
The temperature dependences of the quenching rate constants of the states
N2 (${\rm C} \ {^{3}{
\rm \Pi }_{u}}${\rm C} \ {^{3}{
\rm \Pi }_{u}} v′=0,1) by N2 (X) and of the state
N2 (${\rm C} \ {^{3}{
\rm \Pi }_{u}} \ v^{\prime}=0${\rm C} \ {^{3}{
\rm \Pi }_{u}} \ v^{\prime}=0) by O2 (X) are studied.
Time-resolved light emission from the gas was analyzed in the temperature
range from 300 K to 210 K keeping the gas at constant density. In case of
quenching by N2 (X), the quenching rate constant for the vibrational
level v′= 0 increases by (13 ±3)% with gas cooling whereas the
quenching rate constant for v′= 1 decreases by (5.0 ±2.5)% in this
temperature range. For quenching by O2 (X), the quenching rate constant
decreases by (3 ±2)% with gas cooling. The temperature variation of
the N2 (C 3Πu v′=0) emission intensity for pure nitrogen
and dry air are calculated using the obtained quenching rate constants and
is compared with the experimental data available in the literature. 相似文献
2.
For weakly non ergodic systems, the probability density function of a time average observable
is
where
is the value of the observable when the system is in state j=1,…L. p
j
eq is the probability that a member of an ensemble of systems occupies state j in equilibrium. For a particle undergoing a fractional diffusion process in a binding force field, with thermal detailed
balance conditions, p
j
eq is Boltzmann’s canonical probability. Within the unbiased sub-diffusive continuous time random walk model, the exponent 0<α<1 is the anomalous diffusion exponent 〈x
2〉∼t
α
found for free boundary conditions. When α→1 ergodic statistical mechanics is recovered
. We briefly discuss possible physical applications in single particle experiments. 相似文献
3.
Sergio Albeverio Saidakhmat N. Lakaev Tulkin H. Rasulov 《Journal of statistical physics》2007,127(2):191-220
A model operator H associated with the energy operator of a system describing three particles in interaction, without conservation of the number
of particles, is considered. The location of the essential spectrum of H is described. The existence of infinitely many eigenvalues (resp. the finiteness of eigenvalues) below the bottom τess(H) of the essential spectrum of H is proved for the case where the associated Friedrichs model has a threshold energy resonance (resp. a threshold eigenvalue).
For the number N(z) of eigenvalues of H lying below z < τess(H) the following asymptotics is found
Subject Classification: Primary: 81Q10, Secondary: 35P20, 47N50. 相似文献
4.
Dyson’s model is a one-dimensional system of Brownian motions with long-range repulsive forces acting between any pair of
particles with strength proportional to the inverse of distances with proportionality constant β/2. We give sufficient conditions for initial configurations so that Dyson’s model with β = 2 and an infinite number of particles is well defined in the sense that any multitime correlation function is given by
a determinant with a continuous kernel. The class of infinite-dimensional configurations satisfying our conditions is large
enough to study non-equilibrium dynamics. For example, we obtain the relaxation process starting from a configuration, in
which every point of
\mathbbZ{\mathbb{Z}} is occupied by one particle, to the stationary state, which is the determinantal point process with the sine kernel. 相似文献
5.
We consider the Glauber dynamics for the 2D Ising model in a box of side L, at inverse temperature β and random boundary conditions τ whose distribution P either stochastically dominates the extremal plus phase (hence the quotation marks in the title) or is stochastically dominated by the extremal minus phase. A particular case is when P is concentrated on the homogeneous configuration identically equal to + (equal to ?). For β large enough we show that for any ${\varepsilon >0 }We consider the Glauber dynamics for the 2D Ising model in a box of side L, at inverse temperature β and random boundary conditions τ whose distribution P either stochastically dominates the extremal plus phase (hence the quotation marks in the title) or is stochastically dominated
by the extremal minus phase. A particular case is when P is concentrated on the homogeneous configuration identically equal to + (equal to −). For β large enough we show that for any ${\varepsilon >0 }${\varepsilon >0 } there exists c=c(b,e){c=c(\beta,\varepsilon)} such that the corresponding mixing time T
mix satisfies limL?¥ P(Tmix 3 exp(cLe)) = 0{{\rm lim}_{L\to\infty}\,{\bf P}\left(T_{\rm mix}\ge {\rm exp}({cL^\varepsilon})\right) =0}. In the non-random case τ ≡ + (or τ ≡ −), this implies that Tmix £ exp(cLe){T_{\rm mix}\le {\rm exp}({cL^\varepsilon})}. The same bound holds when the boundary conditions are all + on three sides and all − on the remaining one. The result,
although still very far from the expected Lifshitz behavior T
mix = O(L
2), considerably improves upon the previous known estimates of the form
Tmix £ exp(c L\frac 12 + e){T_{\rm mix}\le {\rm exp}({c L^{\frac 12 + \varepsilon}})}. The techniques are based on induction over length scales, combined with a judicious use of the so-called “censoring inequality”
of Y. Peres and P. Winkler, which in a sense allows us to guide the dynamics to its equilibrium measure. 相似文献
6.
7.
We introduce a family of real random polynomials of degree n whose coefficients a
k
are symmetric independent Gaussian variables with variance
, indexed by a real α≥0. We compute exactly the mean number of real roots 〈N
n
〉 for large n. As α is varied, one finds three different phases. First, for 0≤α<1, one finds that
. For 1<α<2, there is an intermediate phase where 〈N
n
〉 grows algebraically with a continuously varying exponent,
. And finally for α>2, one finds a third phase where 〈N
n
〉∼n. This family of real random polynomials thus exhibits a condensation of their roots on the real line in the sense that, for
large n, a finite fraction of their roots 〈N
n
〉/n are real. This condensation occurs via a localization of the real roots around the values
, 1≪k≤n. 相似文献
8.
Let A
1,…,A
N
be complex self-adjoint matrices and let ρ be a density matrix. The Robertson uncertainty principle
gives a bound for the quantum generalized covariance in terms of the commutators [A
h
,A
j
]. The right side matrix is antisymmetric and therefore the bound is trivial (equal to zero) in the odd case N=2m+1.
Let f be an arbitrary normalized symmetric operator monotone function and let 〈⋅,⋅〉
ρ,f
be the associated quantum Fisher information. Based on previous results of several authors, we propose here as a conjecture
the inequality
whose validity would give a non-trivial bound for any N∈ℕ using the commutators i[ρ,A
h
]. 相似文献
9.
C?t?lin I. Carstea 《Communications in Mathematical Physics》2010,300(2):487-528
The existence of co-rotational finite time blow up solutions to the wave map problem from ${\mathbb{R}^{2+1} \to N}The existence of co-rotational finite time blow up solutions to the wave map problem from
\mathbbR2+1 ? N{\mathbb{R}^{2+1} \to N} , where N is a surface of revolution with metric d
ρ
2 + g(ρ)2
dθ2, g an entire function, is proven. These are of the form u(t,r)=Q(l(t)t)+R(t,r){u(t,r)=Q(\lambda(t)t)+\mathcal{R}(t,r)} , where Q is a time independent solution of the co-rotational wave map equation −u
tt
+ u
rr
+ r
−1
u
r
= r
−2
g(u)g′(u), λ(t) = t
−1-ν, ν > 1/2 is arbitrary, and R{\mathcal{R}} is a term whose local energy goes to zero as t → 0. 相似文献
10.
Magnetocaloric properties of as-quenched Ni50.4Mn34.9In14.7 ferromagnetic shape memory alloy ribbons
Sánchez Llamazares J. L. García C. Hernando B. Prida V. M. Baldomir D. Serantes D. González J. 《Applied Physics A: Materials Science & Processing》2011,103(4):1125-1130
The temperature dependences of magnetic entropy change and refrigerant capacity have been calculated for a maximum field change
of Δ
H=30 kOe in as-quenched ribbons of the ferromagnetic shape memory alloy Ni50.4Mn34.9In14.7 around the structural reverse martensitic transformation and magnetic transition of austenite. The ribbons crystallize into
a single-phase austenite with the L21-type crystal structure and Curie point of 284 K. At 262 K austenite starts its transformation into a 10-layered structurally
modulated monoclinic martensite. The first- and second-order character of the structural and magnetic transitions was confirmed
by the Arrott plot method. Despite the superior absolute value of the maximum magnetic entropy change obtained in the temperature
interval where the reverse martensitic transformation occurs
(|\varDelta SMmax|=7.2 J kg-1 K-1)(|\varDelta S_{\mathrm{M}}^{\max}|=7.2\mbox{ J}\,\mbox{kg}^{-1}\,\mbox{K}^{-1}) with respect to that obtained around the ferromagnetic transition of austenite
(|\varDelta SMmax|=2.6 J kg-1 K-1)(|\varDelta S_{\mathrm{M}}^{\max}|=2.6\mbox{ J}\,\mbox{kg}^{-1}\,\mbox{K}^{-1}), the large average hysteretic losses due to the effect of the magnetic field on the phase transformation as well as the narrow
thermal dependence of the magnetic entropy change make the temperature interval around the ferromagnetic transition of austenite
of a higher effective refrigerant capacity (RCmagneff=95J kg-1\mathrm{RC}^{\mathrm{magn}}_{\mathrm{eff}}=95\mbox{J}\,\mbox{kg}^{-1} versus RCstructeff=60J kg-1)\mathrm{RC}^{\mathrm{struct}}_{\mathrm{eff}}=60\mbox{J}\,\mbox{kg}^{-1}). 相似文献
11.
We construct a family of self-adjoint operators D N , ${N\in{\mathbb Z}}We construct a family of self-adjoint operators D
N
,
N ? \mathbb Z{N\in{\mathbb Z}} , which have compact resolvent and bounded commutators with the coordinate algebra of the quantum projective space
\mathbb CPlq{{\mathbb C}{\rm P}^{\ell}_q} , for any ℓ ≥ 2 and 0 < q < 1. They provide 0+-dimensional equivariant even spectral triples. If ℓ is odd and
N=\frac12(l+1){N=\frac{1}{2}(\ell+1)} , the spectral triple is real with KO-dimension 2ℓ mod 8. 相似文献
12.
B. Ananthanarayan S. Ramanan 《The European Physical Journal C - Particles and Fields》2009,60(1):73-81
The Taylor coefficients c and d of the EM form factor of the pion are constrained using analyticity, knowledge of the phase of the form factor in the time-like
region, 4m
π
2≤t≤t
in and its value at one space-like point, using as input the (g−2) of the muon. This is achieved using the technique of Lagrange multipliers, which gives a transparent expression for the
corresponding bounds. We present a detailed study of the sensitivity of the bounds to the choice of time-like phase and errors
present in the space-like data, taken from recent experiments. We find that our results constrain c stringently. We compare our results with those in the literature and find agreement with the chiral perturbation-theory results
for c. We obtain
when c is set to the chiral perturbation-theory values. 相似文献
13.
S. Rajesh K. P. Murali R. Ratheesh 《Applied Physics A: Materials Science & Processing》2011,104(1):159-164
Rutile filled PTFE composites have been fabricated through Sigma Mixing, Extrusion, Calendering and Hot pressing (SMECH) process.
Dielectric constant (er¢\varepsilon_{r}') and loss tangent (tan δ) of filled composites at microwave frequency region were measured by waveguide cavity perturbation technique using a Vector
Network Analyzer. The temperature coefficient of dielectric constant (ter¢\tau_{\varepsilon_{r}'}) was measured in the 0–100°C temperature range. In order to tailor the temperature coefficient of dielectric constant of
the composite, thermoplastic Poly (ether ether ketone) (PEEK) has been used as a secondary polymer. Flexible laminate having
a dielectric constant, er¢ ~ 10.4\varepsilon_{r}'\sim10.4, loss tangent tan δ∼0.0045 and ter¢ ~ -40 ppm/K\tau_{\varepsilon_{r}'}\sim-40\mbox{ ppm}/\mbox{K} was realized in Polytetrafluroethylene (PTFE)/rutile composites with the addition of 8 wt% PEEK. The reduction in ter¢\tau_{\varepsilon_{r}'} is mainly attributed to the positive ter¢\tau_{\varepsilon_{r}'} of PEEK and increased interface region in the composites as a result of the PEEK addition. 相似文献
14.
Xue-Mei Deng 《Brazilian Journal of Physics》2011,41(4-6):333-348
A modified generalized Chaplygin gas (MGCG) is considered as the unified dark matter–dark energy revisited. The character of MGCG is endued with the dual role, which behaves as matter at early times and as a quiessence dark energy at late times. The equation of state for MGCG is p?=???αρ/(1?+?α)????(z)ρ ???α /(1?+?α) , where $\vartheta(z)=-[\,\rho_{\,\rm 0c}(1+z)^{3}]\,^{(1+\alpha)}(1-\Omega_{\,\rm 0B})^{\alpha}\{\alpha\Omega_{\,\rm 0DM}+ \Omega_{\,\rm 0DE}[\,\omega_{\,\rm DE}+\alpha(1+\omega_{\rm DE})](1+z)^{3\omega_{\rm DE}(1+\alpha)}\}$ . Some cosmological quantities, such as the densities of different components of the universe Ω i (i, respectively, denotes baryons, dark matter, and dark energy) and the deceleration parameter q, are obtained. The present deceleration parameter q 0, the transition redshift z T, and the redshift z eq, which describes the epoch when the densities in dark matter and dark energy are equal, are also calculated. To distinguish MGCG from others, we then apply the Statefinder diagnostic. Later on, the parameters (α and ω DE) of MGCG are constrained by combination of the sound speed $c^{2}_{\rm s}$ , the age of the universe t 0, the growth factor m, and the bias parameter b. It yields $\alpha=-3.07^{+5.66}_{-4.98}\times10^{-2}$ and $\omega_{\rm DE}=-1.05^{+0.06}_{-0.11}$ . Through the analysis of the growth of density perturbations for MGCG, it is found that the energy will transfer from dark matter to dark energy which reach equal at z eq~0.48 and the density fluctuations start deviating from the linear behavior at z~0.25 caused by the dominance of dark energy. 相似文献
15.
Lixin Xu Wenbo Li Jianbo Lu 《The European Physical Journal C - Particles and Fields》2009,60(1):135-140
In this paper, the holographic dark-energy model is considered in Brans–Dicke theory, where the holographic dark-energy density
ρ
Λ
=3c
2
M
pl2
L
−2 is replaced by ρ
h=3c
2
Φ(t)L
−2. Here
is the time-variable Newton constant. With this replacement, it is found that no accelerated expansion for the universe will
be achieved when the Hubble horizon is taken to play the role of an IR cut-off. When the event horizon is adopted as the IR
cut-off, accelerated expansion for the universe is obtained. In this case, the equation of state of holographic dark energy,
w
h, takes the modified form
. In the limit α→0, the ‘standard’ holographic dark energy is recovered. In the holographic dark-energy dominated epoch, power-law and de
Sitter time-space solutions are obtained. 相似文献
16.
We consider a random walk X
n
in ℤ+, starting at X
0=x≥0, with transition probabilities
and X
n+1=1 whenever X
n
=0. We prove
as n
↗∞ when δ∈(1,2). The proof is based upon the Karlin-McGregor spectral representation, which is made explicit for this random walk. 相似文献
17.
Let μ
0 be a probability measure on ℝ3 representing an initial velocity distribution for the spatially homogeneous Boltzmann equation for pseudo Maxwellian molecules.
As long as the initial energy is finite, the solution μ
t
will tend to a Maxwellian limit. We show here that if
, then instead, all of the mass “explodes to infinity” at a rate governed by the tail behavior of μ
0. Specifically, for L0, define
Let B
R
denote the centered ball of radius R. Then for every R,
The explicit rate is estimated in terms of the rate of divergence of η
L
. For example, if η
L
≥Const.L
s
, some s>0,
is bounded by a multiple of e
−[κ3s/(10+9s)]t
, where κ is the absolute value of the spectral gap in the linearized collision operator. Note that in this case, letting B
t
denote the ball of radius e
rt
for any r<κ
s/(10+9s), we still have
.
This result shows in particular that the necessary and sufficient condition for lim
t→∞
μ
t
to exist is that the initial data have finite energy. While the “explosion” of the mass towards infinity in the case of infinite
energy may seem to be intuitively clear, there seems not to have been any proof, even without the rate information that our
proof provides, apart from an analogous result, due to the authors, concerning the Kac equation. A class of infinite energy
eternal solutions of the Boltzmann equation have been studied recently by Bobylev and Cercignani. Our rate information is
shown here to provide a limit on the tails of such eternal solutions.
E. Carlen’s work is partially supported by U.S. National Science Foundation grant DMS 06-00037.
E. Gabetta’s and E. Regazzini’s work is partially supported by Cofin 2004 “Probleme matematici delle teorie cinetiche” (MIUR). 相似文献
18.
B. Sitamtze Youmbi Serge Zékeng Samuel Domngang Florent Calvayrac Alain Bulou 《Ionics》2012,18(4):371-377
To date, the fastest lithium ion-conducting solid electrolytes known are the perovskite-type ABO3 oxide, with A = Li, La and B = Ti, lithium lanthanum titanate (LLTO)
Li3x La( 2 \mathord