scholarly journals Superconducting Properties of 3D Low-Density Translation-Invariant Bipolaron Gas

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
V. D. Lakhno
Keyword(s):  
Heat Capacity ◽  
Transition Energy ◽  
High Temperature Superconductors ◽  
Bose Condensate ◽  
Three Dimensional ◽  
Low Density ◽  
Superconducting Properties ◽  
Translation Invariant ◽  
Thermodynamical Properties ◽  
Transition Heat

Consideration is given to thermodynamical properties of a three-dimensional Bose-condensate of translation-invariant bipolarons (TI-bipolarons). The critical temperature of transition, energy, heat capacity, and the transition heat of ideal TI-bipolaron gas are calculated. The results obtained are used to explain experiments on high-temperature superconductors.

scholarly journals Superconducting Properties of 3D Low-Density TI-Bipolaron Gas in Magnetic Field

2019 ◽  
Vol 4 (2) ◽  
pp. 43 ◽  
Author(s):  
Victor D. Lakhno
Keyword(s):  
Magnetic Field ◽  
High Temperature Superconductors ◽  
Bose Condensate ◽  
Three Dimensional ◽  
Superconducting Properties ◽  
London Penetration Depth ◽  
Translation Invariant ◽  
Thermodynamical Properties ◽  
Critical Magnetic Fields ◽  
Transition Heat

Consideration is given to thermodynamical properties of a three-dimensional Bose-condensate of translation-invariant bipolarons (TI-bipolarons) in magnetic field. The critical temperature of transition, critical magnetic fields, energy, heat capacity and the transition heat of TI-bipolaron gas are calculated. Such values as maximum magnetic field, London penetration depth and their temperature dependencies are calculated. The results obtained are used to explain experiments on high-temperature superconductors.

scholarly journals Translation-Invariant Bipolarons and Charge Density Waves in High-Temperature Superconductors

2021 ◽  
Vol 9 ◽  
Author(s):  
Victor D. Lakhno
Keyword(s):  
Charge Density ◽  
High Temperature Superconductors ◽  
Bose Condensate ◽  
Density Wave ◽  
Charge Density Waves ◽  
Superconducting Transition ◽  
Density Waves ◽  
Translation Invariant ◽  
Pseudogap Phase ◽  
Pair Density

A correlation is established between the theories of superconductivity based on the concept of charge density waves (CDWs) and the translation invariant (TI) bipolaron theory. It is shown that CDWs are originated from TI-bipolaron states in the pseudogap phase due to the Kohn anomaly and form a pair density wave (PDW) for wave vectors corresponding to nesting. Emerging in the pseudogap phase, CDWs coexist with superconductivity at temperatures below those of superconducting transition, while their wave amplitudes decrease as a Bose condensate is formed from TI bipolarons, vanishing at zero temperature.

DIMENSIONAL TRANSITIONS OF DENSITY OF STATES AND HEAT CAPACITY IN SPHERICAL QUANTUM DOTS

2008 ◽  
Vol 22 (15) ◽  
pp. 2373-2382
Author(s):  
SEUNG JOO LEE ◽  
HEE CHANG JEON ◽  
TAE WON KANG ◽  
SATOFUMI SOUMA
Keyword(s):  
Quantum Dots ◽  
Heat Capacity ◽  
Density Of States ◽  
Three Dimensional ◽  
Potential Barrier Height ◽  
Low Density ◽  
Barrier Thickness ◽  
Spherical Quantum Dot ◽  
Thin Barrier ◽  
Density Regime

We evaluate analytically and numerically the density of states (DOS) and the heat capacity in a spherical quantum dot formed by a spherical thin barrier. The control of the spherical barrier thickness or the potential barrier height is found to cause the dimensional transition from the three-dimensional (3D) behavior to the quasi-zero dimensional (Q0D) behavior in the DOS and the heat capacity. When the barrier is thick enough, the DOS shows the Q0D-like behavior but when the barrier is thin enough to allow electrons to tunnel through it, the temperature dependence of the heat capacity exhibits quite a distinct behavior depending on the electron density. Explicit numerical plots are given in the low density regime.

Computational Insights Into Air-Side Flow and Heat Transfer in Compact Heat Exchangers

2005 ◽  
Author(s):  
D. K. Tafti
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Computer Experiments ◽  
Transfer Coefficients ◽  
Substantial Impact ◽  
Compact Heat Exchangers ◽  
Thermal Phenomena ◽  
Side Flow

The paper describes two- and three-dimensional computer simulations which are used to study fundamental flow and thermal phenomena in multilouvered fins used for air-side heat transfer enhancement in compact heat exchangers. Results pertaining to flow transition, thermal wake interference, and fintube junction effects are presented. It is shown that a Reynolds number based on flow path rather than louver pitch is more appropriate in defining the onset of transition, and characteristic frequencies in the louver bank scale better with a global length scale such as fin pitch than with louver pitch or thickness. With the aid of computer experiments, the effect of thermal wakes is quantified on the heat capacity of the fin as well as the heat transfer coefficient, and it is established that experiments which neglect accounting for thermal wakes can introduce large errors in the measurement of heat transfer coefficients. Further, it is shown that the geometry of the louver in the vicinity of the tube surface has a large effect on tube heat transfer and can have a substantial impact on the overall heat capacity.

Additive technology applied to the realization of K-band microwave terminations: reproducibility improvement

2018 ◽  
Vol 10 (1) ◽  
pp. 3-8
Author(s):  
Azar Maalouf ◽  
Ronan Gingat ◽  
Vincent Laur
Keyword(s):  
3D Printing ◽  
Frequency Band ◽  
Rectangular Waveguide ◽  
Three Dimensional ◽  
Low Density ◽  
Support Material ◽  
Additive Technology ◽  
3D Printed ◽  
K Band

This study examines K-band rectangular waveguide terminations with three-dimensional (3D)-printed loads, and proposes an Asymmetrical Tapered Wedge topology. This geometry shows a good tradeoff between microwave performance and 3D-printing issues (printing directions and support material requirements), thus improving noticeably the reproducibility of the devices. The effect of the density of the 3D-printed load on the reflection parameter of the termination was investigated. Even for a low density, reflection level remained below −27.5 dB between 18 and 26.5 GHz. Reproducibility was demonstrated by the characterization of six loads that were 3D printed under the same conditions. Measurements demonstrate that a maximum reflection parameter level of −33.5 dB can be ensured over the whole frequency band without any post-machining of the 3D-printed devices.

λ-Transition to the Bose-Einstein Condensate

1995 ◽  
Vol 50 (10) ◽  
pp. 921-930 ◽  
Author(s):  
Siegfried Grossmann ◽  
Martin Holthaus
Keyword(s):  
Heat Capacity ◽  
Three Dimensional ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Condensation Temperature ◽  
Harmonic Oscillator Potential ◽  
Bose Einstein Condensate ◽  
Bose Einstein ◽  
Analytical Expressions ◽  
Grand Canonical

Abstract We study Bose-Einstein condensation of comparatively small numbers of atoms trapped by a three-dimensional harmonic oscillator potential. Under the assumption that grand canonical statis­tics applies, we derive analytical expressions for the condensation temperature, the ground state occupation, and the specific heat capacity. For a gas of TV atoms the condensation temperature is proportional to N1/3, apart from a downward shift of order N-1/3. A signature of the condensation is a pronounced peak of the heat capacity. For not too small N the heat capacity is nearly discon­tinuous at the onset of condensation; the magnitude of the jump is about 6.6 N k. Our continuum approximations are derived with the help of the proper density of states which allows us to calculate finite-AT-corrections, and checked against numerical computations.

Effect of ZnO Nano-Oxide Addition on the Superconducting Properties of the (Bi.Pb)2223 Phase

2011 ◽  
Vol 324 ◽  
pp. 241-244 ◽  
Author(s):  
R. Mawassi ◽  
R. Awad ◽  
Mohamad Roumie ◽  
M. Kork ◽  
I. Hassan
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
High Temperature Superconductors ◽  
Weak Links ◽  
Superconducting Properties ◽  
X Ray ◽  
Weight Percentage ◽  
Nano Oxide

The major limitation of Bi-system superconductor applications is the intergrain weak links and weak flux pinning capability producing low critical current density of the Bibased phases. In order to enhance these characteristics and other superconducting properties, effective flux pinning centers are introduced into high temperature superconductors. In this work, different weight percentages of ZnO nano oxide were introduced at the final stage of the Bi1.8Pb0.4Sr2Ca2Cu3O10-y superconductor preparation process. Phase characterization was completed by X-ray diffraction (XRD). Exact constitution of the samples was determined using particle induced X-ray emission (PIXE). Granular and microstructure were investigated using scanning electron microscopy (SEM). Electrical resistivity as function of the temperature was carried to evaluate the relative performance of samples, and finally, E-J characteristic curves were obtained at 77K. Using 0.4 ZnO weight percentage, the electrical and granular properties were greatly enhanced, indicating more efficient pinning mechanisms. A critical current density of 949 A/cm2 was obtained which represents more than twice the value obtained for the pure sample (Jc= 445 A/cm2).

scholarly journals Klein–Gordon particle near RN black hole, generalized sl(2) algebra and harmonic oscillator energy

2019 ◽  
Vol 34 (31) ◽  
pp. 1950196
Author(s):  
J. Sadeghi ◽  
M. R. Alipour
Keyword(s):  
Differential Equation ◽  
Information Theory ◽  
Black Hole ◽  
Energy Spectrum ◽  
Harmonic Oscillator ◽  
Three Dimensional ◽  
The Other ◽  
Thermodynamical Properties ◽  
Heun Functions ◽  
Klein Gordon

In this paper, we consider Klein–Gordon particle near Reissner–Nordström black hole. The symmetry of such a background led us to compare the corresponding Laplace equation with the generalized Heun functions. Such relations help us achieve the generalized [Formula: see text] algebra and some suitable results for describing the above-mentioned symmetry. On the other hand, in case of [Formula: see text], which is near the proximity black hole, we obtain the energy spectrum. When we compare the equation of RN background with Laguerre differential equation, we show that the obtained energy spectrum is same as the three-dimensional harmonic oscillator. So, finally we take advantage of harmonic oscillator energy and make suitable partition function. Such function help us to obtain all thermodynamical properties of black hole. Also, the structure of obtained entropy lead us to have some bit and information theory in the RN black hole.

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