TASK Quarterly   Scientific Bulletin of the Centre of Informatics - Tricity Academic Supercomputer & networK   ISSN 1428-6394

Volume 22, Number 2, 2018


Contents:



Abstracts:

  • Wojciech Gwizdała, Violetta Raczyńska, Przemysław Raczyński, Krzysztof Górny and Zbigniew Dendzik On the Ordering of 𝑛-Cyanobiphenyl Mesogene Molecules on Graphene – a Computer Simulation Study

    We studied ultrathin layers of 𝑛-cyanobiphenyl (𝑛 = 5,6,7,8) mesogene molecules forming thin films on a graphene plane using molecular dynamics simulations in a wide temperature range (220–420 K). Each modeled ensemble was heated to the maximum temperature and then cooled (reverse procedure). We calculated the second rank order parameter as a measure of the molecular order of mesogene molecules and we discuss the distribution of angles between them and the global sample director.

  • Donato Pera Design and Performance Evaluation of a Linux HPC Cluster

    In this paper after a short theoretical introduction about modern techniques used in parallel computing, we report a case study related to the design and development of the Caliban Linux High Performance Computing cluster, carried out by the author in the High Performance Computing Laboratory of the University of L'Aquila. Finally we report some performance evaluation tests related to the Caliban cluster performed using HPL (High-Performance Linpack) benchmarks.

  • George J. Papadopoulos Tunneling through a barrier under transverse magnetic field and 𝐼-𝑉 characteristic

    The case whereby the transmission coefficient through a barrier, sandwiched by semiconductor reservoirs, under bias is provided by a general formula involving the logarithmic wave function derivative at the barrier entrance is now extended to include the influence of magnetic field perpendicular to the longitudinal barrier direction. Under the circumstances, the equation governing the logarithmic wave function derivative is appropriately modified via an effective potential energy which takes account of the magnetic field. Subsequently, the procedure for obtaining the transmission coefficient is applied to the case involving a smooth double, as well as quadruple, barrier for which the 𝐼-𝑉 characteristic is obtained. The results show reduction in current with increase in the magnetic field, up to a certain value of bias. Furthermore, increase in temperature exhibits increase in current as well as movement of the current peaks in the 𝐼-𝑉 curves towards lower bias.

  • Leonardo Pasini Evaluation of the Impact of Changes in the City Road System on Traffic Flows

    This paper outlines a study carried out to answer the questions asked by an architect of the Siena Municipality Office during a conference at our Department on the management of traffic flows through the Siena North city road system. The purpose of the study was to ascertain if changes in the road system introduced and included in the new City Development Plan would resolve the current traffic congestion issues. In order to answer this question, we used the technology for the development of vehicle traffic system simulators which was introduced during our previous projects (TASK Quart. 14 (4) 405, 17 (3) 155, 20 (1) 9, 20 (3) 273).