scholarly journals Sensitivity of steady states in a degenerately damped stochastic Lorenz system

2021 ◽  
pp. 2150055
Author(s):  
Juraj Földes ◽  
Nathan E. Glatt-Holtz ◽  
David P. Herzog
Keyword(s):  
Lyapunov Functions ◽  
Lorenz System ◽  
Invariant Probability Measure ◽  
The Other ◽  
Stability Of Solutions ◽  
Invariant State ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Positive Growth ◽  
Null Recurrence

We study stability of solutions for a randomly driven and degenerately damped version of the Lorenz ’63 model. Specifically, we prove that when damping is absent in one of the temperature components, the system possesses a unique invariant probability measure if and only if noise acts on the convection variable. On the other hand, if there is a positive growth term on the vertical temperature profile, we prove that there is no normalizable invariant state. Our approach relies on the derivation and analysis of nontrivial Lyapunov functions which ensure positive recurrence or null-recurrence/transience of the dynamics.

scholarly journals EFFECT OF DUST AEROSOL LAYER ON VERTICAL TEMPERATURE PROFILE

MAUSAM ◽  
2022 ◽  
Vol 53 (4) ◽  
pp. 539-542
Author(s):  
A. P. DIMRI ◽  
V. K. JAIN ◽  
B. B. DASH
Keyword(s):  
Temperature Profile ◽  
Dust Aerosol ◽  
Aerosol Layer ◽  
Vertical Temperature ◽  
Vertical Temperature Profile

scholarly journals A Hydrodynamical Model for Calculating the Vertical Temperature Profile in Lakes During Cooling

1983 ◽  
Vol 14 (4) ◽  
pp. 239-254 ◽  
Author(s):  
Jörgen Sahlberg
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Vertical Mixing ◽  
Hydrodynamical Model ◽  
Measured Temperature ◽  
Vertical Temperature ◽  
Mixing Rate ◽  
Mixing Processes ◽  
Vertical Temperature Profile ◽  
Radiation Fluxes

A one-dimensional hydrodynamical model is used for simulating the vertical temperature profile in a lake during cooling conditions. The vertical mixing rate is calculated by solving the equations for turbulent kinetic energy, k, and dissipation of energy, ε. The heat exchange between the water and atmosphere consists of the radiation fluxes, sensible and latent heat flux. Temperature measurements from Lake Väsman during November-December, 1981, were used in the verification study. The agreement between calculated and measured temperature profiles is very good. This indicates that both the mixing processes and the net heat flux are well described in the model.

Heteroclinic Trajectory and Hopf Bifurcation in an Extended Lorenz System

2018 ◽  
Vol 28 (09) ◽  
pp. 1850111
Author(s):  
Xianyi Li ◽  
Haijun Wang
Keyword(s):  
Hopf Bifurcation ◽  
Lyapunov Function ◽  
Numerical Simulations ◽  
Lorenz System ◽  
The Other ◽  
Hopf Bifurcations ◽  
Limit Sets ◽  
Initial Values ◽  
Heteroclinic Trajectory ◽  
The One

This note revisits an extended Lorenz system, which was presented in the paper entitled “Hopf bifurcations in an extended Lorenz system” by Zhou et al. [2017]. On the one hand, one points out and corrects some wrong results in that paper on the Hopf bifurcation at the symmetric equilibria [Formula: see text] and [Formula: see text]. On the other hand, combining Lyapunov function and the concepts of [Formula: see text]- and [Formula: see text]-limit sets, it is rigorously proved that there exists two and only two heteroclinic trajectories but no homoclinic trajectories under some certain conditions of its parameters and initial values. In addition, numerical simulations illustrate the consistence with the theoretical conclusions. The results together not only improve and complement the known ones, but also provide support in some future applications.

scholarly journals 2.5D retrieval of atmospheric properties from exoplanet phase curves: application to WASP-43b observations

2020 ◽  
Vol 493 (1) ◽  
pp. 106-125 ◽  
Author(s):  
Patrick G J Irwin ◽  
Vivien Parmentier ◽  
Jake Taylor ◽  
Jo Barstow ◽  
Suzanne Aigrain ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Water Vapour ◽  
Mole Fraction ◽  
Phase Curve ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Retrieval Technique ◽  
The Mean ◽  
Synthetic Phase ◽  
Model Phase

ABSTRACT We present a novel retrieval technique that attempts to model phase curve observations of exoplanets more realistically and reliably, which we call the 2.5-dimensional (2.5D) approach. In our 2.5D approach we retrieve the vertical temperature profile and mean gaseous abundance of a planet at all longitudes and latitudes simultaneously, assuming that the temperature or composition, x, at a particular longitude and latitude (Λ, Φ) is given by $x(\Lambda ,\Phi) = \bar{x} + (x(\Lambda ,0) - \bar{x})\cos ^n\Phi$, where $\bar{x}$ is the mean of the morning and evening terminator values of x(Λ, 0), and n is an assumed coefficient. We compare our new 2.5D scheme with the more traditional 1D approach, which assumes the same temperature profile and gaseous abundances at all points on the visible disc of a planet for each individual phase observation, using a set of synthetic phase curves generated from a GCM-based simulation. We find that our 2.5D model fits these data more realistically than the 1D approach, confining the hotter regions of the planet more closely to the dayside. We then apply both models to WASP-43b phase curve observations of HST/WFC3 and Spitzer/IRAC. We find that the dayside of WASP-43b is apparently much hotter than the nightside and show that this could be explained by the presence of a thick cloud on the nightside with a cloud top at pressure <0.2 bar. We further show that while the mole fraction of water vapour is reasonably well constrained to (1–10) × 10−4, the abundance of CO is very difficult to constrain with these data since it is degenerate with temperature and prone to possible systematic radiometric differences between the HST/WFC3 and Spitzer/IRAC observations. Hence, it is difficult to reliably constrain C/O.

Influence de la variété de Vigna unguiculata dans l'expression de trois associations endomycorhiziennes à vésicules et arbuscules

1983 ◽  
Vol 61 (1) ◽  
pp. 354-358 ◽  
Author(s):  
B. Ollivier ◽  
Y. Bertheau ◽  
H. G. Diem ◽  
V. Gianinazzi-Pearson
Keyword(s):  
Electrophoretic Mobility ◽  
Vigna Unguiculata ◽  
Glomus Mosseae ◽  
The Other ◽  
Growth Effect ◽  
Alkaline Phosphatases ◽  
Va Mycorrhizas ◽  
Vesicular Arbuscular ◽  
Positive Growth ◽  
Mycorrhizal Roots

Vesicular–arbuscular (VA) mycorrhizas formed by Glomus E3, G. mosseae, and G. epigaeus have been studied in two cultivars of Vigna unguiculata L. Walp. (58-185 and Bambey 30). Glomus mosseae and Glomus E3 stimulated the growth of both cultivars while G. epigaeus only gave a positive growth effect with the cultivar 58-185. With G. epigaeus, infection levels were lower and growth effects smaller than with the other VA fungi. Growth stimulations were accompanied by the appearance of additional soluble alkaline phosphatases in extracts of mycorrhizal roots. The number and the electrophoretic mobility of these enzymes varied depending on the VA fungus involved, suggesting that they were of fungal origin.

An Experimental Research on Wall Radiant Cooling and Wall-Attached-Jet Air-Conditioning System

2014 ◽  
Vol 501-504 ◽  
pp. 2244-2251 ◽  
Author(s):  
Xiang Lei Kong ◽  
Xin Li Zi ◽  
Long Yun ◽  
Xiao Song Zhang
Keyword(s):  
Indoor Air ◽  
Air Conditioning ◽  
Stable Operation ◽  
Displacement Ventilation ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Air Conditioning System ◽  
Radiant Cooling ◽  
Operation Period ◽  
The Subject

Taking the radiant cooling combined with wall-attached-jet air-conditioning system as the subject in a laboratory of Jiangsu university, an experimental study was carried out on pre-dehumidifying period, stable operation period and system shutdown period, along with analysis. The objective is to analyze the pre-dehumidification of the system, indoor air temperature and humidification change, vertical temperature profile and condensation sensitivity. The results show that the hybrid air-conditioning can provide high thermal comfort and avoid condensation effectively, which shows the better performance compared to the system of radiant cooling combined with displacement ventilation to some extent.

Sign in / Sign up

Export Citation Format

Share Document