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Liu C.,Hunan Normal University | Liu C.,Hunan Institute of Humanities, Science and Technology | Chen S.,Hunan Normal University | Jing J.,Hunan Normal University
Astrophysical Journal | Year: 2012

The properties of the ergosphere and energy extraction by the Penrose process in a rotating non-Kerr black hole are investigated. It is shown that the ergosphere is sensitive to the deformation parameter ε and the shape of the ergosphere becomes thick as parameter ε increases. It is of interest to note that, compared with the Kerr black hole, the deformation parameter ε can enhance the maximum efficiency of the energy extraction process greatly. Especially for the case of a > M, the non-Kerr metric describes a superspinning compact object and the maximum efficiency can exceed 60%, while it is only 20.7% for the extremal Kerr black hole. © 2012. The American Astronomical Society. All rights reserved..


Liu C.,Hunan Normal University | Liu C.,Hunan Institute of Humanities, Science and Technology | Chen S.,Hunan Normal University | Ding C.,Hunan Institute of Humanities, Science and Technology | Jing J.,Hunan Normal University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We study the collision of two particles with the different rest masses moving in the equatorial plane of a Kerr-Taub-NUT spacetime and get the center-of-mass (CM) energy for the particles. We find that the CM energy depends not only on the rotation parameter, a, but also on the NUT charge of the Kerr-Taub-NUT spacetime, n. Especially, for the extremal Kerr-Taub-NUT spacetime, an unlimited CM energy can be approached if the parameter a is in the range [1,2], which is different from that of the Kerr and Kerr-Newman black holes. © 2011 Elsevier B.V.


Ding C.,Hunan Institute of Humanities, Science and Technology | Jing J.,Hunan Normal University
Journal of High Energy Physics | Year: 2011

Abstract: We study the influence of the spacetime noncommutative parameter on the strong field gravitational lensing in the noncommutative Reissner-Nordström black-hole spacetime. Supposing that the gravitational field of the supermassive central object of the Galaxy is described by this metric, we estimate the numerical values of the coefficients and observables for strong gravitational lensing. Our results show that with the increase of the parameter √θ, the observables θ∞ and rm decrease, while s increases. Our results also show that i) if √θ is strong, the observables are close to those of the noncommutative Schwarzschild black hole lensing; ii) if √θ is weak, the observables are close to those of the commutative Reissner-Nordström black hole lensing; iii) the detectable scope of √ in a noncommutative Reissner-Nordström black hole lensing is 0.12 ≤ √θ ≤ 0.26, which is wider than that in a noncommutative Schwarzschild black hole lensing, 0.18 ≤ √θ ≤ 0.26. This may offer a way to probe the spacetime noncommutative constant √ by the astronomical instruments in the future. © 2011 SISSA.


Yao W.,Hunan Normal University | Chen S.,Hunan Normal University | Liu C.,Hunan Normal University | Liu C.,Hunan Institute of Humanities, Science and Technology | Jing J.,Hunan Normal University
European Physical Journal C | Year: 2012

Department of Physics and Information Engineering, Hunan Institute of Humanities Science and Technology, Loudi, Hunan 417000, P.R. China Received: 27 October 2011 / Revised: 7 January 2012 Abstract We study the collision of two geodesic particles in the accelerating and rotating black hole spacetime and probe the effects of the acceleration of black hole on the center-of-mass energy of the colliding particles and on the high-velocity collision belts. We find that the dependence of the center-of-mass energy on the acceleration in the near event-horizon collision is different from that in the near acceleration-horizon case. Moreover, the presence of the acceleration changes the shape and position of the highvelocity collision belts. Our results show that the acceleration of black holes brings about richer physics for the collision of particles. © Springer-Verlag / Società Italiana di Fisica 2012.


Hu C.,Hunan Institute of Humanities, Science and Technology | Guo J.,Hunan Institute of Humanities, Science and Technology | Wen J.,Hunan Institute of Humanities, Science and Technology | Peng Y.,Hunan Institute of Humanities, Science and Technology
Journal of Materials Science and Technology | Year: 2013

A hydrometallurgical process for the recovery of cobalt oxalate from spent lithium-ion batteries was used to recycle cobalt compound by using alkali leaching, reductive acid leaching and chemical deposition of cobalt oxalate. The recycled cobalt oxalate was used to synthesize nano-Co3O4 anode material by sol-gel method. The samples were characterized by thermal gravity analysis and differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and charge/discharge measurements. The influence of molar ratio of Co2+ to citric acid and calcination temperature on the structure and electrochemical performance of nano-Co3O4 was evaluated. As the molar ratio of Co2+ to citric acid is 1:1, the face-centered cubic (fcc) Co3O4 powder shows the discharge capacity of 760.9 mA h g-1, the high coulombic efficiency of 99.7% in the first cycle at the current density of 125 mA g-1, and the excellent cycling performance with the reversible capacity of 442.3 mA h g-1 after 20 cycles at the current density of 250 mA g-1. © 2013.


Zhou Y.,Hunan Institute of Humanities, Science and Technology
Proceedings - 2013 5th Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2013 | Year: 2013

One of the most important reason which restricting engineering application is that matrix converter voltage transfer ratio can not be greater than 0.866. Therefore, to improve the voltage transfer ratio method has important practical significance. There are three effective methods to improve the matrix converter voltage transfer ratio. They are harmonic injection method and a new topology. The feasibility and effectiveness of two methods are proving from analyzing their basic principles, comparing their characteristics and Simulation study. The simulation results show that the first method can increase the voltage transfer ratio to 1.0 or so, but the output voltage of the harmonic content is increased accordingly, the second method of the voltage transfer ratio can reach or exceed 1.0, and the output voltage of the harmonic content is small, The comparative research of the two methods can provide some reference for project application. © 2013 IEEE.


Li S.,Hunan Institute of Humanities, Science and Technology
2013 IEEE 3rd International Conference on Information Science and Technology, ICIST 2013 | Year: 2013

Pairwise key establishment is a fundamental security service for sensor networks. However, establishing pairwise key in sensor networks is a challenging problem, due to the resource constraints on nodes and the threat of node capture. In this paper, a new pairwise key establishment scheme is proposed. Analysis and simulation show that the proposed scheme can achieve higher security as compared with the existing schemes. © 2013 IEEE.


Hu C.,Hunan Institute of Humanities, Science and Technology | Guo J.,Hunan Institute of Humanities, Science and Technology | Wen J.,Hunan Institute of Humanities, Science and Technology
Ionics | Year: 2013

Copper oxide particles with different morphology (flower-like, peach kernel-like, and dandelion-like) are prepared with hydrothermal method by adjusting chitosan ((C6H11NO4)n) concentration in aqueous mixed solutions of ammonia and Cu(NO3)2. Various morphologies of porous cupric oxide (CuO) particles are formed by agglomerated nanosheet primary particles and lead to different electrochemical performance of electrodes. The peach kernel-shaped CuO exhibits high reversible capacity and rate capability. The reversible capacity is 722. 7 mAh g-1 at 0. 1 C in the first cycle and 339 mAh g-1 after 50 cycles at 0. 2, 0. 5, 1. 0, and 2. 0 C ratio. The higher reversible capacities and good cycling performance are attributed to the larger specific surface area, leading to better contact between CuO and electrolyte. © 2012 Springer-Verlag.


Liu C.-Q.,Hunan Institute of Humanities, Science and Technology
Chinese Physics Letters | Year: 2010

The low energy absorption cross section and the decay rate of the stationary Axisymmetric Einstein-Maxwell Dilaton Axion black hole for massless scalar particles is calculated analytically. It is shown that the partial absorption cross section increases as the rotating parameter a and the absolute value of the dilaton D decreases. It is also shown that the partial absorption cross section is not always positive due to superradiance factor ω-mΩ. However, the decay rate of this black hole is always positive. © 2010 Chinese Physical Society and IOP Publishing Ltd.


Liu C.-Q.,Hunan Institute of Humanities, Science and Technology
Chinese Physics Letters | Year: 2013

Collision of two general geodesic particles around the Kerr - Newman black hole is studied and the center-of-mass (cm.) energy of the non-marginally and marginally bound critical particles in the direct collision and the last stable orbit collision scenarios is obtained. The constraint conditions that arbitrarily high cm. energy can be obtained for the near-horizon collision of two general geodesic particles in the extremal Kerr - Newman black hole is found, and it is noted that the charge decreases the value of the latitude in which arbitrarily high cm. energy can occur. © 2013 Chinese Physical Society and IOP Publishing Ltd.

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