Investigation of Structural,Electronic and Mechanical Properties of Rubidium Metal Hydrides RbMH_4(M=B,Al, Ga)

Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of rubidium metal hydrides RbMH4(M = B, Al, Ga) for five different crystal structures, namely hexagonal(P63mc), tetragonal(P42/nmc), tetragonal(P421c), orthorhombic(Pnma) and monoclinic(P21/c). Among the considered structures, tetragonal(P421c) phase is found to be the most stable one for these metal hydrides at normal pressure. A pressure-induced structural phase transition from tetragonal(P421c) to monoclinic(P21/c) phase is observed in all the three metal hydrides. The electronic structure reveals that these hydrides are wide band gap semiconductors. The calculated elastic constants indicate that these alkali metal tetrahydrides are mechanically stable at normal pressure.     

A novel cascade encryption algorithm for digital images based on anti-synchronized fractional order dynamical systems

In this paper, an active control technique is employed for anti-synchronization between two identical fractional order reverse butterfly-shaped hyperchaotic systems. We have shown that the convergence rate of anti-synchronization error is very faster by increasing the value of an active controller gain. A new algorithm for image encryption and decryption is introduced and established by anti-synchronized fractional order dynamical systems. Experimental results show that the proposed encryption algorithm has high level security against various attacks. Further, it confirms that the new algorithm is more efficient compared to other existing algorithms.     

A new journal power-weakness ratio to measure journal impact

Scientometrics - Journal impact indicators are useful measures to determine the relative importance of journals within a given discipline. By recasting the journal cross-citation matrix as a...     

The structure of collaboration in the Journal of Finance

This paper studies the structure of collaboration in the Journal of Finance for the period 1980–2009 using publication data from the Social Sciences Citation Index (SSCI). There are 3,840 publications within this period, out of which 58% are collaborations. These collaborations form 405 components, with the giant component capturing approximately 54% of total coauthors (it is estimated that the upper limit of distinct JF coauthors is 2,536, obtained from the total number of distinct author keywords found within the study period). In comparison, the second largest component has only 13 members. The giant component has mean degree 3 and average distance 8.2. It exhibits power-law scaling with exponent α = 3.5 for vertices with degree ≥5. Based on the giant component, the degree, closeness and betweenness centralization score, as well as the hubs/authorities score is determined. The findings indicate that the most important vertex on the giant component coincides with Sheridan Titman based on his top ten ranking on all four scores.     

International research collaborations of ASEAN Nations in economics, 1979–2010

This study examines the research performance and international research collaborations (IRC) of ASEAN nations in the area of economics. Over the last 3 decades international collaborated papers have increased in the region, while locally-co-authored papers have declined. Singapore towered among ASEAN nations in research efficiency based on geographical area, population and GDP. Vietnam performed relatively better in research efficiency than research productivity (number of papers produced), while Indonesia performed poorly. Overall, internationally co-authored papers were cited twice as often as locally authored papers except that both The Philippines and Indonesia exhibited almost no difference in how their local and internationally co-authored papers were cited. The study also examined IRC from the perspective of social networks. Centrality had a strong correlation with research performance; however, vertex tie-strength (a result of repeat collaboration) showed maximum correlation with research performance. While Malaysia emerged as the nation with the highest betweenness centrality or ‘bridging’ power, the US emerged as the most favoured international partner of ASEAN nations. However, collaboration between ASEAN countries accounted for just 4 % of all international collaborations. Increased academic mobility and more joint scientific works are suggestions to consider to boost educational co-operation among the ASEAN nations.     

Mode-Dependent H_{\infty } Filtering for Stochastic Markovian Switching Genetic Regulatory Networks with Leakage and Time-Varying Delays

In this paper, the \(H_{\infty }\) filtering problem is considered for Markovian switching genetic regulatory networks (GRNs) with mode-dependent leakage and time-varying delays along intrinsic molecular fluctuations and extrinsic molecular noises. The aim of this paper is to design a filter to estimate the true concentrations of mRNAs and proteins. By choosing suitable Lyapunov–Krasovskii functionals and reciprocally convex combination approach, sufficient conditions are obtained to ensure that the filtering error system is globally stochastically stable in the mean-square sense with the prescribed \(H_{\infty }\) disturbance attenuation levels. The existence of the designed \(H_{\infty }\) filters is expressed in terms of linear matrix inequalities (LMIs), which can be easily solved by using Matlab LMI toolbox. Also the corresponding results are obtained for the GRNs without leakage delays. Finally, two numerical examples are given, which include a repressilator model of Escherichia coli to illustrate the effectiveness of the proposed theoretical results.