Radiation and mass transfer effects on unsteady MHD free convection flow of an incompressible viscous fluid past a moving vertical cylinder

The interaction of free convection with thermal radiation of a viscous incompressible unsteady MHD flow past a moving vertical cylinder with heat and mass transfer is analyzed. The fluid is a gray, absorbing-emitting but non-scattering medium and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing equations are solved using an implicit finite-difference scheme of Crank-Nicolson type. Numerical results for the transient velocity, the temperature, the concentration, the local as well as average skin-friction, the rate of heat and mass transfer for various parameters such as thermal Grashof number, mass Grashof number, magnetic parameter, radiation parameter and Schmidt number are shown graphically. It is observed that, when the radiation parameter increases the velocity and temperature decrease in the boundary layer. Also, it is found that as increase in the magnetic field leads to decrease in the velocity field and rise in the thermal boundary thickness

Sampling-Based Query Re-Optimization

Despite of decades of work, query optimizers still make mistakes on "difficult" queries because of bad cardinality estimates, often due to the interaction of multiple predicates and correlations in the data. In this paper, we propose a low-cost post-processing step that can take a plan produced by the optimizer, detect when it is likely to have made such a mistake, and take steps to fix it. Specifically, our solution is a sampling-based iterative procedure that requires almost no changes to the original query optimizer or query evaluation mechanism of the system. We show that this indeed imposes low overhead and catches cases where three widely used optimizers (PostgreSQL and two commercial systems) make large errors.Comment: This is the extended version of a paper with the same title and authors that appears in the Proceedings of the ACM SIGMOD International Conference on Management of Data (SIGMOD 2016

Star-forming Galaxies in the 'Redshift Desert'

We describe results of optical and near-IR observations of a large spectroscopic sample of star-forming galaxies photometrically-selected to lie in the redshift range 1.4 < z < 2.5, often called the ``redshift desert'' because of historical difficulty in obtaining spectroscopic redshifts in this range. We show that the former ``redshift desert'' is now very much open to observation.Comment: 10 pages, 6 figures, to appear in the Proceedings of the ESO/USM/MPE Workshop on "Multiwavelength Mapping of Galaxy Formation and Evolution", eds. R. Bender and A. Renzin

High speed script execution for GUI automation using computer vision

Software testing by using open source tool like Selenium windows applications cannot be automated, citrix based applications, flash websites and games. Computer vision based automation tools can be used to automate these kinds of applications.  These automation tools works based on screenshots of GUI objects like button, radio button, text box, images, dropdowns etc. In this paper a prototype of automation tool has been developed which can execute the automation scripts much faster than existing tools like Sikuli, which takes much time to run the Automation scripts. The execution time can be reduced by using this proposed tool

Performance Enhancement of TCP Friendly Rate Control Protocol over Wired networks

One of the main aims of transport layer protocol is achieving best throughput without any congestion or reduced congestion.  With rapid growing application needs and with increasing number of networks in Internet, there is a primary need to design new protocols to transport layer.  To transmit multimedia applications, one of the suitable congestion control mechanisms in transport layer is TCP Friendly Rate Control Protocol (TFRC).  It controls congestion based on its equation. However, every packet requires an acknowledgement in TFRC. It creates congestion in the network when the transmitted data is very large, which results in reduced throughput. This paper aims to increase the throughput when the transmitted data is large with minimal congestion by reducing the number of acknowledgements in the network.  We modified some fixed parameters in the TFRC equation. The results show the increased throughput with minimal congestion

An Enhanced Queue Management Scheme for Eradicating Congestion of TFRC over Wired Environment

To accomplish increasing real time requirements, user applications have to send different kinds of data with different speeds over the internet.  To effectuate the aims of the computer networks, several protocols have been added to TCP/IP protocol suite.  Transport layer has to implement emerging techniques to transfer huge amount of data like multimedia streaming. To transmit multimedia applications, one of the suitable congestion control mechanisms in transport layer is TCP Friendly Rate Control Protocol (TFRC).  It controls congestion based on its equation. To get more smoothed throughput, intermediate nodes (like Routers. etc.) have to use suitable procedures in all real time situations. To eradicate the level of congestion in the network, we introduce enhanced Holt-Winters equations to RED queue management algorithm and applied to TFRC. The simulation results have shown that this strategy reduces packet loss and increases throughput

Heating rate measurements over 30 deg and 40 deg (half angle) blunt cones in air and helium in the Langley expansion tube facility

Convective heat transfer measurements, made on the conical portion of spherically blunted cones (30 deg and 40 deg half angle) in an expansion tube are discussed. The test gases used were helium and air; flow velocities were about 6.8 km/sec for helium and about 5.1 km/sec for air. The measured heating rates are compared with calculated results using a viscous shock layer computer code. For air, various techniques to determine flow velocity yielded identical results, but for helium, the flow velocity varied by as much as eight percent depending on which technique was used. The measured heating rates are in satisfactory agreement with calculation for helium, assuming the lower flow velocity, the measurements are significantly greater than theory and the discrepancy increased with increasing distance along the cone

Carrier induced ferromagnetism in concentrated and diluted local-moment systems

For modeling the magnetic properties of concentrated and diluted magnetic semiconductors, we use the Kondo-lattice model. The magnetic phase diagram is derived by inspecting the static susceptibility of itinerant band electrons, which are exchange coupled to localized magnetic moments. It turns out that rather low band occupations favour a ferromagnetic ordering of the local moment systems due to an indirect coupling mediated by a spin polarization of the itinerant charge carriers. The disorder in diluted systems is treated by adding a CPA-type concept to the theory. For almost all moment concentrations x, ferromagnetism is possible, however, only for carrier concentrations n distinctly smaller than x. The charge carrier compensation in real magnetic semiconductors (in Ga_{1-x}Mn_{x}As by e.g. antisites) seems to be a necessary condition for getting carrier induced ferromagnetism.Comment: 9 pages (REVTeX), 6 figures, to be published in Phys. Rev.