Frequency-dependent (ac) Conduction in Disordered Composites: a Percolative Study

In a recent paper [Phys. Rev. B{\bf57}, 3375 (1998)], we examined in detail the nonlinear (electrical) dc response of a random resistor cum tunneling bond network ($RRTN$, introduced by us elsewhere to explain nonlinear response of metal-insulator type mixtures). In this work which is a sequel to that paper, we consider the ac response of the $RRTN$-based correlated $RC$ ($CRC$) model. Numerical solutions of the Kirchoff's laws for the $CRC$ model give a power-law exponent (= 0.7 near $p = p_c$) of the modulus of the complex ac conductance at moderately low frequencies, in conformity with experiments on various types of disordered systems. But, at very low frequencies, it gives a simple quadratic or linear dependence on the frequency depending upon whether the system is percolating or not. We do also discuss the effective medium approximation ($EMA$) of our $CRC$ and the traditional random $RC$ network model, and discuss their comparative successes and shortcomings.Comment: Revised and reduced version with 17 LaTeX pages plus 8 JPEG figure

Scheduling and efficient energy utilization in cloud system

Cloud computing is an emerging topic on software and distributed computing based on Internet, which means users can access storages and applications from remote servers by web browsers or other fixed or mobile terminals. In a cloud framework different services such as servers, storage in the form of data as well as Big data, resources etc are given to a management's computers and different devices on interest through the Internet. Multiple clients want to run their jobs or cloudlets in the cloud at a particular instant of time. The tasks are executed depending on the number of processors available and the scheduling policy of the cloud. In a cloud simulation software such as CloudSim a two level scheduling in the form of Space-shared and Time-shared can be used in collaboration with First Come First Serve(FCFS). An efficient way of job scheduling in cloud is to assign weightage or priority to the various parameters coming along with the job also taking into consideration the priority value set by the client to the task. In this thesis an attempt has been made to develop an efficient priority algorithm for the jobs running in the cloud. Also an attempt has been made to reduce the energy consumption at a particular over utilized node as well as switching idle nodes to the sleep mode thereby optimizing resource usage and reducing energy consumption

Cosmic optical activity from an inhomogeneous Kalb-Ramond field

The effects of introducing a harmonic spatial inhomogeneity into the Kalb-Ramond field, interacting with the Maxwell field according to a `string-inspired' proposal made in earlier work are investigated. We examine in particular the effects on the polarization of synchrotron radiation from cosmologically distant (i.e. of redshift greater than 2) galaxies, as well as the relation between the electric and magnetic components of the radiation field. The rotation of the polarization plane of linearly polarized radiation is seen to acquire an additional contribution proportional to the square of the frequency of the dual Kalb-Ramond axion wave, assuming that it is far smaller compared to the frequency of the radiation field.Comment: 9 pages, Revtex, no figure