Dynamics of a Charged Particle Around a Slowly Rotating Kerr Black Hole Immersed in Magnetic Field

The dynamics of a charged particle moving around a slowly rotating Kerr black hole in the presence of an external magnetic field is investigated. We are interested to explore the conditions under which the charged particle can escape from the gravitational field of the black hole after colliding with another particle. The escape velocity of the charged particle in the innermost stable circular orbit is calculated. The effective potential and escape velocity of the charged particle with angular momentum in the presence of magnetic field is analyzed. This work serves as an extension of a preceding paper dealing with the Schwarzschild black hole [Zahrani {\it et al}, Phys. Rev. D 87, 084043 (2013)].Comment: 20 pages, 12 figure

A study of positive energy condition in Bianchi V spacetimes via Noether symmetries

In this paper we use Noether symmetries of the geodesic Lagrangian in Bianchi V spacetimes to study various cosmological solutions of Einstein's field equations. Our first result is the identification of the subalgebras of Noether symmetries of the equations of motions in such spacetimes with dimension 4, 5, 6, 7, 9 or 10 of the maximal algebra of Lie point symmetries of dimension 13. Secondly we give physical interpretation of new cosmological solutions which satisfy positive energy condition and yield critical bounds on the expansion coefficient $\alpha$, in which the underlying non-flat spacetimes carry interesting physical properties. Specifically the energy density behaves in one of the following ways. (i) It is positive and constant for all time. (ii) It varies with time and attains a global maximum after some time and then asymptotically converges to zero. (iii) It increases for all time and attains a maximum value at the asymptotic limit $t\rightarrow \infty$. In particular a non-flat spacetime is obtained that mimics the expansion in a flat FRW universe dominated by vacuum energy such that the expansion factor has the same form in both. However, the energy density is dynamical in the former.Comment: Some typos are corrected. Some considerations into f(R) gravity is also carried out in the light of obtained results. Accepted for publication in EPJ

Time-constrained nature-inspired optimization algorithms for an efficient energy management system in smart homes and buildings

This paper proposes two bio-inspired heuristic algorithms, the Moth-Flame Optimization (MFO) algorithm and Genetic Algorithm (GA), for an Energy Management System (EMS) in smart homes and buildings. Their performance in terms of energy cost reduction, minimization of the Peak to Average power Ratio (PAR) and end-user discomfort minimization are analysed and discussed. Then, a hybrid version of GA and MFO, named TG-MFO (Time-constrained Genetic-Moth Flame Optimization), is proposed for achieving the aforementioned objectives. TG-MFO not only hybridizes GA and MFO, but also incorporates time constraints for each appliance to achieve maximum end-user comfort. Different algorithms have been proposed in the literature for energy optimization. However, they have increased end-user frustration in terms of increased waiting time for home appliances to be switched ON. The proposed TG-MFO algorithm is specially designed for nearly-zero end-user discomfort due to scheduling of appliances, keeping in view the timespan of individual appliances. Renewable energy sources and battery storage units are also integrated for achieving maximum end-user benefits. For comparison, five bio-inspired heuristic algorithms, i.e., Genetic Algorithm (GA), Ant Colony Optimization (ACO), Cuckoo Search Algorithm (CSA), Firefly Algorithm (FA) and Moth-Flame Optimization (MFO), are used to achieve the aforementioned objectives in the residential sector in comparison with TG-MFO. The simulations through MATLAB show that our proposed algorithm has reduced the energy cost up to 32.25% for a single user and 49.96% for thirty users in a residential sector compared to unscheduled load

Synthesis of Homophthalates, 2-(Arylsulfonyl)pyridines, 6-(Thien-2-yl)salicylates, Dibenzo[b,d]pyran-6-ones, Trifluoromethyl- and Fluoro-Substituted Biaryls by [4+2] and [3+3] Cyclizations of 1,3-Bis(silyloxy)-1,3-butadienes

One-pot cyclization reactions of 1,3-bis(silyl enol ethers) with the different electrophiles provide a convenient approach for the synthesis of various complex carbacycles and heterocycles from simple starting materials. 6-Hetaryl-salicylates and 4-Aryl and 4-Hetaryl-salicylates were prepared based on [3+3] cyclizations of 1,3-bis(sily enol ethers) in an efficient way. Dibenzo[b,d]pyran-6-ones were synthesized by formal [3+3] cyclization of 1,3-bis(silyl enol ethers) with 1-(2-methoxyphenyl)-1-(trimethylsilyloxy)alk-1-en-3-ones and subsequent BBr3-mediated lactonization. Aryl fluorides were synthesized by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 2-fluoro-3-silyloxy-2-en-1-ones. 1,3-Bis(silyl enol ethers) were used efficiently for the synthesis of highly functionalized homomphthalates and 4-hydoxypyridines based on [4+2] cyclization reactions.Ein-Topf Cyclisierungensreaktionen von 1,3-Bis(silylenolethern) mit unterschiedlichen Elektrophilen ermöglicht einen bequemen Zugang zu einer großen Bandbreite von Carba- und Heterocyclen ausgehend von einfachen Startmaterialien. 6-Hetaryl-salicylate und 4-Aryl und 4-Hetaryl-salicylate wurde durch [3+3] Cyclisierungen von 1,3-Bis(silyenolethern) auf effiziente Weise hergestellt. Weiterhin wurden Dibenzo[b,d]pyran-6-one durch formale [3+3] Cyclisierungen von 1,3-Bis(silylenolethern) mit 1-(2-Methoxyphenyl)-1-(trimethylsilyloxy)alk-1-en-3-onen und anschließende BBr3-vermittelte Lactonisierung synthetisiert. Arylfluoride wurden durch [3+3] Cyclisierungen von 1,3-Bis(silylenolethern) mit 2-Fluoro-3-silyloxy-2-en-1-onen hergestellt. 1,3-Bis(silylenolether) wurden weiterhin als Bausteine für die Synthese hochfunktionalisierter Homomphthalate und 4-Hydoxypyridine durch [4+2] Cycloadditionen erfolgreich eingesetzt

Detecting Spam Review through Spammer’s Behavior Analysis

Online reviews about the purchase of a product or services provided have become the main source of user opinions. To gain profit or fame usually spam reviews are written to promote or demote some target products or services. This practice is known as review spamming. In the last few years, different methods have been suggested to solve the problem of review spamming but there is still a need to introduce new spam review detection method to improve accuracy results. In this work, researchers have studied six different spammer behavioral features and analyzed the proposed spam review detection method using weight method. An experimental evaluation was conducted on a benchmark dataset and achieved 84.5% accuracy

Generalized Second Law of Thermodynamics for FRW Cosmology with Power-Law Entropy Correction

In this work, we have considered the power law correction of entropy on the horizon. If the flat FRW Universe is filled with the n components fluid with interactions, the GSL of thermodynamics for apparent and event horizons have been investigated for equilibrium and non-equilibrium cases. If we consider a small perturbation around the de Sitter space-time, the general conditions of the validity of GSL have been found. Also if a phantom dominated Universe has a polelike type scale factor, the validity of GSL has also been analyzed. Further we have obtained constraints on the power-law parameter {\alpha} in the phantom and quintessence dominated regimes. Finally we obtain conditions under which GSL breaks down in a cosmological background.Comment: 10 page