LMI based Stability and Stabilization of Second-order Linear Repetitive Processes

This paper develops new results on the stability and control of a class of linear repetitive processes described by a second-order matrix discrete or differential equation. These are developed by transformation of the secondorder dynamics to those of an equivalent first-order descriptor state-space model, thus avoiding the need to invert a possibly ill-conditioned leading coefficient matrix in the original model

Comparative seedling morphology of four species of Sida (Malvaceae) from Tripura, India and their taxonomic implications

Comparative seedling morphology of four Sida species occurring in Tripura were investigated. Seedling characters (germination pattern, position of cotyledon, hypocotyl, epicotyl and paracotyledon and eophylls development) were found to be important and promising from the taxonomic as well as evolutionary point of view. These characters provide important diagnostic character of the species of the genus. Phenogram based on UPGMA method has been prepared and correlation between the characters of seedling of four Sida species were studied

Seed and seedling morphology of some medicinal plants of family Malvaceae in Tripura, North-east India

Plants in their juvenile stage possess some important characters which are very important and promising from the taxonomic as well as evolutionary point of view. Seed and Seedling morphology of ten species of Malvaceae has been investigated on the basis of their germination pattern, position of cotyledon, hypocotyl, epicotyl and paracotyledon and eophylls development. An artificial key has been constructed for easier identification of plants in their juvenile stage. Phenogram has been made by using UPGMA analysis to investigate the correlation between the investigated taxa

Discrete Element Method (DEM) Analysis of Non-Cohesive Granular Material Flow in Hoppers

Hoppers, silos and bins are expected to store material and provide unrestricted and uniform flow of the same in mate-rial processing plants. Traditionally, the material flow from hopper is analyzed assuming the solid mass as contin-uum. However, the behavior of particulate solids deviates significantly from a continuous system, due to fluctuation in its bulk material properties (e.g. bulk density) throu-ghout the process. In the present work, a numerical techn-ique called discrete element method (DEM) is used to analyze granular material flow from hopper. DEM tracks the _trajectories of individual particles as they interact with their neighboring particles and hopper walls. These interactions ultimately translate to the overall displace-ment of the particles. The scheme is repeated in small time intervals covering the complete duration of the proc-ess. Here the simulations are limited to non-cohesive sphe-rical granular material. Material flow is studied as a function of hopper geometry. This article involves visua-lization and flow rate analysis of coarse particles for different hopper design

Exchange coupling between two ferromagnetic electrodes separated by a graphene nanoribbon

In this study, based on the self-energy method and the total energy calculation, the indirect exchange coupling between two semi-infinite ferromagnetic strips (FM electrodes) separated by metallic graphene nanoribbons (GNRs) is investigated. In order to form a FM/GNR/FM junction, a graphitic region of finite length is coupled to the FM electrodes along graphitic zigzag or armchair interfaces of width $N$. The numerical results show that, the exchange coupling strength which can be obtained from the difference between the total energies of electrons in the ferromagnetic and antiferromagnetic couplings, has an oscillatory behavior, and depends on the Fermi energy and the length of the central region.Comment: 4 pages, 6 figures, International Conference on Theoretical Physics 'Dubna-Nano2008

Metal-insulator transition in an aperiodic ladder network: an exact result

We show, in a completely analytical way, that a tight binding ladder network composed of atomic sites with on-site potentials distributed according to the quasiperiodic Aubry model can exhibit a metal-insulator transition at multiple values of the Fermi energy. For specific values of the first and second neighbor electron hopping, the result is obtained exactly. With a more general model, we calculate the two-terminal conductance numerically. The numerical results corroborate the analytical findings and yield a richer variety of spectrum showing multiple mobility edges.Comment: 4 pages, 3 figure

Temperature Profiles of Accretion Disks around Rapidly Rotating Neutron Stars in General Relativity and Implications for Cygnus X-2

We calculate the temperature profiles of (thin) accretion disks around rapidly rotating neutron stars (with low surface magnetic fields), taking into account the full effects of general relativity. We then consider a model for the spectrum of the X-ray emission from the disk, parameterized by the mass accretion rate, the color temperature and the rotation rate of the neutron star. We derive constraints on these parameters for the X-ray source Cygnus X-2 using the estimates of the maximum temperature in the disk along with the disk and boundary layer luminosities, using the spectrum inferred from the EXOSAT data. Our calculations suggest that the neutron star in Cygnus X-2 rotates close to the centrifugal mass-shed limit. Possible constraints on the neutron star equation of state are also discussed.Comment: 18 pages, 9 figs., 2 tables, uses psbox.tex and emulateapj5.sty. Submitted to Ap