Weakly Coupled Dusty Plasma With a High Dust Temperature and Low Thermal Energy Density

2013 ◽  
Vol 41 (4) ◽  
pp. 784-787 ◽  
Author(s):  
Ross Fisher ◽  
Edward Thomas
Keyword(s):  
Energy Density ◽  
Dusty Plasma ◽  
Thermal Energy ◽  
Random Motion ◽  
The Other ◽  
Space Distribution ◽  
Weakly Coupled ◽  
Plasma Species ◽  
Dust Component ◽  
Area Of Concern

Relatively large values of the temperature for the dust component of plasma systems are an area of concern in the understanding of such systems. Dust temperatures are regularly observed to be several orders of magnitude higher than the temperatures of the other plasma components, leading to questions of the validity of the measurements. In order to address such concerns, the phase space distribution was measured for a weakly coupled dusty plasma system. The measurements are used to illustrate the differences between two metrics of the thermal motion of the dust component, namely, the temperature and the thermal energy density. It is shown that, by considering the thermal energy density, instead of the temperature, the energy associated with the random motion of the dust component is comparable to that of the other plasma species.

scholarly journals Supernova constraints on an axion-photon-dark photon interaction

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Anson Hook ◽  
Gustavo Marques-Tavares ◽  
Clayton Ristow
Keyword(s):  
Longitudinal Mode ◽  
Transverse Mode ◽  
The Other ◽  
Unusual Feature ◽  
Dark Sector ◽  
Longitudinal Modes ◽  
Dark Photon ◽  
Transverse Modes ◽  
Weakly Coupled ◽  
Photon Coupling

Abstract We present the supernova constraints on an axion-photon-dark photon coupling, which can be the leading coupling to dark sector models and can also lead to dramatic changes to axion cosmology. We show that the supernova bound on this coupling has two unusual features. One occurs because the scattering that leads to the trapping regime converts axions and dark photons into each other. Thus, if one of the two new particles is sufficiently massive, both production and scattering become suppressed and the bounds from bulk emission and trapped (area) emission both weaken exponentially and do not intersection The other unusual feature occurs because for light dark photons, longitudinal modes couple more weakly than transverse modes do. Since the longitudinal mode is more weakly coupled, it can still cause excessive cooling even if the transverse mode is trapped. Thus, the supernova constraints for massive dark photons look like two independent supernova bounds super-imposed on top of each other.

A New Method for Displacement Analysis of Multi-Loop Spatial Linkages Based on Ordered Simple-Opened-Chains

1996 ◽  
Author(s):  
Xian-Wen Kong ◽  
Ting-Li Yang
Keyword(s):  
Continuation Method ◽  
The Other ◽  
New Method ◽  
New Approach ◽  
Strongly Coupled ◽  
Displacement Analysis ◽  
Cpu Time ◽  
Base Points ◽  
Weakly Coupled ◽  
Spatial Linkages

Abstract This paper presents systematically a new method for the displacement analysis (DA) of multi-loop spatial linkages (MLSLs) based on ordered simple-opened-chains (SOCs). In performing DA, a MLSL is converted into not a set of base points, a set of isolated links or a tree with/without isolated links in common use, but a weakly coupled MLSL in this paper. The characteristics of the proposed method are: (a) The number of unknowns in the set of equations for displacement analysis (EDA) of a MLSL is reduced to the minimum; (b) All the possible configurations corresponding to a given set of inputs of a weakly coupled MLSL or a strongly coupled MLSL with the coupled degree k = 1 can be obtained quickly. As compared with the other two methods available to find all the solutions to the DA in the case of MLSL with k = 1, the proposed method is superior to the resultant method in that it is applicable to more complex MLSLs and superior to the continuation method in that it takes much less CPU time to find all the solutions; (c) The set of EDA can be formulated and solved automatically; and (d) The new approach makes it possible to perform the kinematic and kineto-static analyses in a unified and simplified way.

scholarly journals On the Definition of Energy Flux in One-Dimensional Chains of Particles

Entropy ◽  
2019 ◽  
Vol 21 (11) ◽  
pp. 1036
Author(s):  
Paolo De Gregorio
Keyword(s):  
Energy Density ◽  
Integral Operator ◽  
Energy Flux ◽  
Ad Hoc ◽  
The Other ◽  
Energy Density Distribution ◽  
One Dimensional ◽  
Integral Quantity ◽  
Definition Of ◽  
Local Quantity

We review two well-known definitions present in the literature, which are used to define the heat or energy flux in one dimensional chains. One definition equates the energy variation per particle to a discretized flux difference, which we here show it also corresponds to the flux of energy in the zero wavenumber limit in Fourier space, concurrently providing a general formula valid for all wavelengths. The other relies somewhat elaborately on a definition of the flux, which is a function of every coordinate in the line. We try to shed further light on their significance by introducing a novel integral operator, acting over movable boundaries represented by the neighboring particles’ positions, or some combinations thereof. By specializing to the case of chains with the particles’ order conserved, we show that the first definition corresponds to applying the differential continuity-equation operator after the application of the integral operator. Conversely, the second definition corresponds to applying the introduced integral operator to the energy flux. It is, therefore, an integral quantity and not a local quantity. More worryingly, it does not satisfy in any obvious way an equation of continuity. We show that in stationary states, the first definition is resilient to several formally legitimate modifications of the (models of) energy density distribution, while the second is not. On the other hand, it seems peculiar that this integral definition appears to capture a transport contribution, which may be called of convective nature, which is altogether missed by the former definition. In an attempt to connect the dots, we propose that the locally integrated flux divided by the inter-particle distance is a good measure of the energy flux. We show that the proposition can be explicitly constructed analytically by an ad hoc modification of the chosen model for the energy density.

Characterization of Metal-PCMs for Thermal Energy Storage Applications

2015 ◽  
Vol 830-831 ◽  
pp. 505-508 ◽  
Author(s):  
R. Sudheer ◽  
K. Narayan Prabhu
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Cooling Curve ◽  
Energy Storage Materials ◽  
Energy Storage Applications ◽  
Temperature Applications

In recent years phase change materials have emerged to be ideal energy storage materials for their higher energy density over sensible heat storing materials. Use of phase change materials (PCM) have been successfully implemented at lower temperature applications with various organic compounds. On the other hand, high temperature applications have been solely dominated by various salts, their eutectics and mixtures as phase change materials. This work discusses the suitability of metals and alloys for thermal energy storage applications as the phase change material. Metals offer superior thermal conductivities with considerable energy density compared to salts. Here, two alloys namely, Sn-0.3Ag-0.7Cu (SAC) solidifying over 212-224°C and ZA8 (Zn-8%Al) solidifying over 378-405°C have been studied. Thermal analysis of PCMs using Computer Aided Cooling Curve Analysis (CA-CCA) and DSC technique were performed to predict the solidification path. In addition to this, Newtonian technique was employed to estimate the latent heat of fusion for these phase change materials. Cooling rate curves and Fraction Solid curves offered a better insight into their ability to receive and discharge heat over the concerned temperature range.

scholarly journals Applications of light speed expansion and gravitational self-energy density in black hole cosmology

2015 ◽  
Vol 3 (2) ◽  
pp. 123
Author(s):  
Satya Seshavatharam UV ◽  
Terry Tatum E ◽  
Lakshminarayana S
Keyword(s):  
Black Hole ◽  
Energy Density ◽  
Thermal Energy ◽  
Planck Scale ◽  
Cosmic Inflation ◽  
Self Energy ◽  
Light Speed ◽  
Cosmological Observations ◽  
The Universe ◽  
Matter Energy

<p>From the beginning of Planck scale to the scale of the current Hubble radius: 1) Considering the relation, subjects of black holes and cosmology, both can be integrated into evolving black hole cosmology and cosmic horizon problem can be relinquished. 2) Considering ‘continuous light speed expansion’ of the cosmic black hole horizon, attributed results of cosmic inflation can be re-addressed completely. If ‘nature’ of the universe is to expand with light speed, then there is no need to think about the existence of currently believed ‘Lambda term’. In addition, ‘light speed expanding cosmic space’ can be called as ‘flat space’. 3) Considering the ratio of gravitational self-energy density and thermal energy density to be  (where  is the Planck scale temperature, and is cosmic temperature at any time). Quantum gravity can be implemented in low energy scale current cosmological observations. Considering the above concepts, currently believed dark matter energy density and visible matter energy density both can be accurately fitted with the ratio of current gravitational self-energy density and current thermal energy density. To proceed further, the authors would like to highlight the following three points: 1) Deep-space red shift non-linearity can be expected to be connected with cosmological gravitational and relativistic effects and cannot be considered as a major criterion of cosmic evolution. 2) Until one finds solid applications of super luminal speeds and super luminal expansions in other areas of physics like astrophysics and nuclear astrophysics, currently believed ‘cosmic inflation’ cannot be considered as a real physical model and alternative proposals of inflation can be given a chance in exploring the evolving history of the universe. 3) Implementing Planck scale in current paradigm of cosmological observations and standard cosmology is very challenging and is inevitable.</p>

scholarly journals STATIC CYLINDRICALLY SYMMETRIC INTERIOR SOLUTIONS IN f(R) GRAVITY

2012 ◽  
Vol 27 (25) ◽  
pp. 1250138 ◽  
Author(s):  
M. SHARIF ◽  
SADIA ARIF
Keyword(s):  
Energy Density ◽  
Exact Solutions ◽  
Perfect Fluid ◽  
Functional Form ◽  
Ricci Scalar ◽  
The Other ◽  
New Exact Solutions ◽  
Cylindrically Symmetric ◽  
Theory Of Gravity ◽  
Interior Solutions

We investigate some exact static cylindrically symmetric solutions for a perfect fluid in the metric f(R) theory of gravity. For this purpose, three different families of solutions are explored. We evaluate energy density, pressure, Ricci scalar and functional form of f(R). It is interesting to mention here that two new exact solutions are found from the last approach, one is in particular form and the other is in the general form. The general form gives a complete description of a cylindrical star in f(R) gravity.

HOMOCLINIC BIFURCATION AND CHAOS IN COUPLED SIMPLE PENDULUM AND HARMONIC OSCILLATOR UNDER BOUNDED NOISE EXCITATION

2005 ◽  
Vol 15 (01) ◽  
pp. 233-243 ◽  
Author(s):  
W. Q. ZHU ◽  
Z. H. LIU
Keyword(s):  
Harmonic Oscillator ◽  
Random Motion ◽  
Homoclinic Bifurcation ◽  
Mean Square ◽  
Bounded Noise ◽  
Bifurcation And Chaos ◽  
Simple Pendulum ◽  
Onset Of Chaos ◽  
Weakly Coupled ◽  
Threshold Amplitude

The homoclinic bifurcation and chaos in a system of weakly coupled simple pendulum and harmonic oscillator subject to light dampings and weakly external and (or) parametric excitation of bounded noise is studied. The random Melnikov process is derived and mean-square criteria is used to determine the threshold amplitude of the bounded noise for the onset of chaos in the system. The threshold amplitude is also determined by vanishing the numerically calculated maximal Lyapunov exponent. The threshold amplitudes are further confirmed by using the Poincaré maps, which indicate the path from periodic motion to chaos or from random motion to random chaos in the system as the amplitude of bounded noise increases.

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