Open Access Original Research Article

Non-relativistic Bose-Einstein Condensates, Kaon Droplets, and Q-balls

Zohar Nussinov, Shmuel Nussinov

Physical Science International Journal, Page 1-11
DOI: 10.9734/PSIJ/2016/24118

We note the similarity between BEC (Bose-Einstein Condensates) formed of atoms between which we have long-range attraction (and shorter-range repulsions) and the field theoretic ”Q balls”. This allows us in particular to address the stability of various putative particle physics Q balls made of non-relativistic bosons (K0’s, B0’s and D0’s) using variational methods of the many-body NRS equation.

Open Access Original Research Article

Electron Inertia Effects on the Gravitational Instability under the Influence of FLR Corrections and Suspended Particles

D. L. Sutar, R. K. Pensia

Physical Science International Journal, Page 1-12
DOI: 10.9734/PSIJ/2016/22850

In this paper, we investigate the effects of electron inertia on the gravitational instability of gaseous plasma under the influence of FLR (Finite Larmor Radius) corrections and suspended particles. A general dispersion relation has been derived through relevant linearized perturbation equations. The general dispersion relation is reduced for both longitudinal and transverse mode of propagation. Numerical calculations have been performed to show the effect of various parameters on the growth rate of the gravitational instability. It is found that the simultaneous effect of viscosity, finite conductivity and permeability of the medium does not essentially change the Jeans criterion of instability. From the curves, we find that relaxation time, Stoke drag, viscosity and FLR parameter have a stabilizing effect on the growth rate of instability, but the thermal conductivity and finite electron inertia parameter have a destabilizing effect on the growth rate of instability.

 

Open Access Original Research Article

F Theory Compactifications and Central Charges of BPS States

Tetiana V. Obikhod

Physical Science International Journal, Page 1-6
DOI: 10.9734/PSIJ/2016/24190

F-theory, as Theory of everything is compactified on Calabi-Yau threefolds or fourfolds. Using Batyrev’s toric approximation and mirror symmetry of Calabi-Yau manifolds it is possible to present Calabi-Yau in the form of dual integer polyhedra. With the help of Gelfand, Zelevinsky, Kapranov algorithm are calculated the numbers of BPS-states in F-theory, and by application of Tate’s algorithm are determined the enhanced symmetries. As the result, any integral dual polyhedron representing a Calabi-Yau manifold, is characterized by its own set of topological invariants - the numbers of BPS-states, whose central charges are classified by enhanced symmetries.

 

Open Access Original Research Article

Calculation the Thermal Conductivity of Nanofluids Containing Aligned Ultralong Single Walled Carbon Nanotubes

Nguyen Manh Hong, Bui Hung Thang, Phan Ngoc Minh

Physical Science International Journal, Page 1-8
DOI: 10.9734/PSIJ/2016/24520

The thermal conductivity of carbon nanotubes (CNTs) depends on their length and the diameter. At room temperature, the thermal conductivity of CNTs increases as its length increases as well as its diameter decreases. Aligned long single-walled carbon nanotubes (AL-SWCNTs) are expected to be an ideal candidate for heat transfer materials owing to their small diameter, very long length and high thermal conductivity. In this work, we propose a theory model for thermal conductivity of AL-SWCNTs in nanofluids. The calculation results showed that the thermal conductivity enhancement of AL-SWCNTs nanofluids was about 18.5 times higher than that of MWCNTs nanofluids. The calculation results have confirmed the advantage of the AL-SWCNTs as excellent additive for nanofluids.

 

Open Access Original Research Article

Stability Analysis of the Micro-Grid Operation in Micro-Grid Mode Based on Particle Swarm Optimization (PSO) Including Model Information

Seyed Morteza Moghimi, Seyed Mohammad Shariatmadar, Reza Dashti

Physical Science International Journal, Page 1-13
DOI: 10.9734/PSIJ/2016/24425

Aims: Create a control policy for improve the quality of optimal voltage - frequency (V-F) power supply and stability analysis in a micro-grid scenario include DG units.

Study Design: Control policy for respond to sudden changes such as starting micro-grid mode, and or in load change conditions was designed.

Place and Duration of Study: IAU, Iran, February 2015-January 2016.

Methodology: This paper with using of particle swarm optimization (PSO), model information analysis, and voltage and frequency stability of a micro-grid is controlled. Proposed controller of model include an inner current control loop and an outer power control loop based on synchronous reference frame and conventional PI regulators.

Results: Simulation results show satisfactory performance voltage and frequency of system. Also, results show that proposed control policies established by acceptable limits voltage and frequency of system, and support from output power per some of DG unit in duration of load changes. In addition, simulation results improved system stability under proposed power controller and reduce errors in the proposed controller. The proposed PSO algorithm has good performance for finding the desired optimal control parameters to achieve the control objectives. Thus, automated enforcement mechanism based on the model information has been developed to determine these limits.

Conclusion: The paper is presented a power (V-F) control policy for micro-grid based on PSO algorithm. This is done by proposed voltage and frequency controller based on PSO algorithm for real-time self-tuning. Besides, fast dynamic response and an acceptable level of harmonic distortion as two main basic system performance parameters were obtained. The main objectives are supplied power quality improvement and power stability, otherwise in faced to sudden changes such as transition from connection to grid mode to island mode or load change is located.

 

Open Access Original Research Article

Analysis of Electron Correlation in the Modified Single-band Hubbard Model

Edison A. Enaibe, Akpata Erhieyovwe, Nelson Nenuwe

Physical Science International Journal, Page 1-13
DOI: 10.9734/PSIJ/2016/24969

The major characteristic of the single-band Hubbard model (HM) is to redistribute electrons at a uniform lattice separation distance within the molecular lattice. Hence, it is only linearly dependent on lattice separations distance. Thus the single-band Hubbard model does not consider the lattice gradient encountered by interacting electrons as they hop from one lattice point to another. The linear dependence of the single-band HM only on lattice separations would certainly not provide a thorough understanding of the interplay between interacting electrons. Consequently, we have in this study developed a gradient Hamiltonian model to solve the associated defects pose by the limitations of the single band Hubbard model. Thus, we utilized the single-band HM and the gradient Hamiltonian model to study the behaviour of two interacting electrons on a two dimensional (2D) 9X9 square lattice.  It is revealed in this study that the results of the ground-state energies produced by the gradient Hamiltonian model are more favourable when compared to those of the single-band Hubbard model. We have also shown in this work, that the repulsive Coulomb interaction which in part leads to the strong electronic correlations, would indicate that the two electron system prefer not to condense into s-wave superconducting singlet state (s = 0), at high positive values of the interaction strength.