LOWERING OF BOSON-FERMION SYSTEM ENERGY WITH A GAPPED COOPER RESONANT-PAIR DISPERSION RELATION

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2335-2347 ◽  
Author(s):  
T. A. MAMEDOV ◽  
M. DE LLANO
Keyword(s):  
Pair Formation ◽  
Positive Energy ◽  
Total System ◽  
Fermion System ◽  
Number Density ◽  
Temperature Dependent ◽  
Continuous Processes ◽  
Free Fermions ◽  
Composite Bosons ◽  
System Energy

Applying two-time Green-function techniques to the Friedberg-T.D. Lee phenomenological Hamiltonian of a many-fermion system, it is shown that positive-energy resonant bosonic pairs associated with four-fermion excitations above the Fermi sea are energetically lower in a ground-state that is a mixture of two coexisting and dynamically interacting many-particle subsystems: a) unpaired fermions and b) composite bosons. It is argued that an interaction between free fermions and bosons excited above the Fermi sea in the mixture, namely, the continuous processes of pair-formation from, and disintegration into, two unpaired electrons, results in a substantially lowering the total system energy. The positive-energy composite bosons begin to appear incoherently below a depairing temperature T* as their coupling- and temperature-dependent number density gradually increases from zero. This leads quite naturally to the pseudogap phenomenon observed in high-Tc cuprates.

scholarly journals Non-dissipative hydrodynamic equations based on a nonlocal collision integral

2018 ◽  
Vol 26 (1) ◽  
pp. 11-18
Author(s):  
V. N. Gorev ◽  
A. I. Sokolovsky
Keyword(s):  
Particle Number ◽  
Evolution Equations ◽  
Particle Number Density ◽  
Collision Integral ◽  
Second Order ◽  
Total System ◽  
Hydrodynamic Equations ◽  
Number Density ◽  
Total Energy Density ◽  
System Energy

We consider a slightly non-uniform one-component gas with weak potential interaction. The basis of the investigation is the known kinetic equation in the case of small interaction which is truncated up to the second order of smallness. This equation contains a nonlocal collision integral of the second order in small interaction. In this paper we consider the hydrodynamic stage of the system evolution, and, in contrast to the standard hydrodynamics, we take into account the non-locality of the collision integral. We propose the following set of the reduced description parameters which are the densities of the conserved quantities: the particle number density, the momentum density, and the total energy density. It should be stressed that in contrast to the standard hydrodynamics, the kinetic energy is not conserved, and only the total system energy is conserved if the nonlocal collision integral is used. Definitions of the system velocity and temperature are proposed; it should be stressed that the proposed temperature definition is based on the total system energy rather than on the kinetic one. The hydrodynamics in the leading order in small gradients is investigated, and it is shown that the system one-particle distribution function in the leading-in-gradients order coincides with the Maxwellian one. Particle number density, velocity and temperature time evolution equations (hydrodynamic equations) are derived in the non-dissipative case. The leading-in-interaction orders of the obtained equations coincide with the corresponding equations in the framework of the standard hydrodynamics. The corrections of the first and second order in small interaction are also obtained.

TEMPERATURE OF NONEQUILIBRIUM LATTICE SYSTEMS

2006 ◽  
Vol 17 (12) ◽  
pp. 1703-1715 ◽  
Author(s):  
ALBERTO PETRI ◽  
M. J. DE OLIVEIRA
Keyword(s):  
Monte Carlo ◽  
Heat Bath ◽  
Bath Temperature ◽  
Total System ◽  
Local Distribution ◽  
Lattice Systems ◽  
Potts Models ◽  
Monte Carlo Dynamics ◽  
Instantaneous Temperature ◽  
System Energy

We investigate the thermal quench of Ising and Potts models via Monte Carlo dynamics. We find that the local distribution of the site-site interaction energy has the same form as in the equilibrium case, a result that allows us to define an instantaneous temperature θ during the systems relaxation. We also find that, after an undercritical quench, θ equals the heat bath temperature in a finite time, while the total system energy is still decreasing due to the coarsening process.

Parametric Control of Structural Vibrations via Adaptable Stiffness Dynamic Absorbers

1996 ◽  
Vol 118 (1) ◽  
pp. 41-47 ◽  
Author(s):  
J. S. Lai ◽  
K. W. Wang
Keyword(s):  
Fuzzy Logic ◽  
Vibration Amplitude ◽  
Control Law ◽  
Total System ◽  
Structural Vibrations ◽  
Main Structure ◽  
Parametric Control ◽  
Control Actions ◽  
System Energy ◽  
Globally Stable

An energy-based algorithm is developed for dynamic absorbers with adaptable stiffness to suppress structural vibrations via real-time parametric control actions. A controller with multi-objective fuzzy logic is created to reduce the main structure energy while constraining the total system energy. To ensure stability, an adaptive-passive supervisor is designed to provide guidelines for implementing the control law. It is proved that the system using this supervisor is globally stable in the sense that all signals involved are bounded. The performance of the controller is demonstrated on a beam example. It is shown that the structure energy level and vibration amplitude can be suppressed effectively.

Adsorption-Oxidation of CH3OH on V2O5; Reactivity of the Structural Defects

1998 ◽  
Vol 05 (02) ◽  
pp. 515-518
Author(s):  
Jorge Sambeth ◽  
Luis Gambaro ◽  
Horacio Thomas
Keyword(s):  
Oxidation Process ◽  
Structural Defects ◽  
Electron Delocalization ◽  
Total System ◽  
Extended Hückel ◽  
Extended Hückel Method ◽  
Hückel Method ◽  
System Energy

In previous work the CH 3 OH adsorption–oxidation process on the (010) plane of V 2 O 5 was studied both theoretically and experimentally. In the present work, we have studied this process on idealized structural defects (kinks, steps, corners) of the (010) plane of V 2 O 5. The study was based on calculations of the variation of the total system energy by the extended Hückel method (ASED — atom superposition and electron delocalization). The results demonstrated that the oxidation of CH 3 OH to H 2 CO on the (010) plane is more favorable than on the structural defects and that the kink can be suitable for the oxidation of CH 3 OH to CO 2.

Exploring The Consequences of Negative Triple Junction Energy

2001 ◽  
Vol 703 ◽  
Author(s):  
Gaurav K. Gupta ◽  
Alexander H. King
Keyword(s):  
Grain Size ◽  
Free Energy ◽  
Grain Growth ◽  
Triple Junction ◽  
Driving Force ◽  
Three Dimensional ◽  
Total System ◽  
System Energy ◽  
Dimensional Models ◽  
Three Dimensional Models

ABSTRACTWe have investigated the consequences of negative triple junction energy in grain growth. Two and three-dimensional models for total system energy, incorporating varying triple junction energy are developed. These models show that there is a decrease in overall system energy with grain size corresponding to the driving force for grain growth. Although the free energy available to drive grain growth is reduced under some conditions, it is never removed for any reasonable values of the triple junction energy.

scholarly journals L 2 C: Combining Lossy and Lossless Compression on Memory and I/O

2022 ◽  
Vol 21 (1) ◽  
pp. 1-27
Author(s):  
Albin Eldstål-Ahrens ◽  
Angelos Arelakis ◽  
Ioannis Sourdis
Keyword(s):  
Execution Time ◽  
State Of The Art ◽  
Real Life ◽  
Lossless Compression ◽  
General Purpose ◽  
Constrained Systems ◽  
Access Time ◽  
Total System ◽  
Compression Scheme ◽  
System Energy

In this article, we introduce L 2 C, a hybrid lossy/lossless compression scheme applicable both to the memory subsystem and I/O traffic of a processor chip. L 2 C employs general-purpose lossless compression and combines it with state-of-the-art lossy compression to achieve compression ratios up to 16:1 and to improve the utilization of chip’s bandwidth resources. Compressing memory traffic yields lower memory access time, improving system performance, and energy efficiency. Compressing I/O traffic offers several benefits for resource-constrained systems, including more efficient storage and networking. We evaluate L 2 C as a memory compressor in simulation with a set of approximation-tolerant applications. L 2 C improves baseline execution time by an average of 50% and total system energy consumption by 16%. Compared to the lossy and lossless current state-of-the-art memory compression approaches, L 2 C improves execution time by 9% and 26%, respectively, and reduces system energy costs by 3% and 5%, respectively. I/O compression efficacy is evaluated using a set of real-life datasets. L 2 C achieves compression ratios of up to 10.4:1 for a single dataset and on average about 4:1, while introducing no more than 0.4% error.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

Mass Determination by Direct Measurement of Electron Scattering

1975 ◽  
Vol 33 ◽  
pp. 240-241
Author(s):  
M. K. Lamvik ◽  
A. V. Crewe
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Mass Density ◽  
Variable Mass ◽  
Scattering Cross Section ◽  
Mass Determination ◽  
Number Density ◽  
Cross Sectional ◽  
Thin Slice ◽  
Scattering Cross

If a molecule or atom of material has molecular weight A, the number density of such units is given by n=Nρ/A, where N is Avogadro's number and ρ is the mass density of the material. The amount of scattering from each unit can be written by assigning an imaginary cross-sectional area σ to each unit. If the current I0 is incident on a thin slice of material of thickness z and the current I remains unscattered, then the scattering cross-section σ is defined by I=IOnσz. For a specimen that is not thin, the definition must be applied to each imaginary thin slice and the result I/I0 =exp(-nσz) is obtained by integrating over the whole thickness. It is useful to separate the variable mass-thickness w=ρz from the other factors to yield I/I0 =exp(-sw), where s=Nσ/A is the scattering cross-section per unit mass.

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