Vol. 21, No 3, 2017 < Volumes
(ISSN 1428-6394)



hLeonardo Pasini Queuing networks to evaluate web applications: modelling

The aim of this work is to define a procedure for the modelling of a computer network for the simulation of the network traffic induced by the execution of web applications. The work consists in describing the objects of a library defined for modelling both the hardware and the software of the system. These are specific objects with an architecture based on complex queuing service structures. The objects of the library are used to both build the computer network model and describe the operation of a web application executed on the network in a distributed fashion.


hTomasz Dziubich Qualitative evaluation of distributed clinical systems supporting research teams working on large-scale data

In this paper, five contemporary scalable systems to support medical research teams are presented. Their functionalities extend from heterogeneous unstructured data acquisition through large-scale data storing, to on-the-fly analyzing by using robust methods. Such kinds of systems can be useful in the development of new medical procedures and recommendation rules for decision support systems. A short description of each of them is provided. Further, a set of the most important features is selected, and a comparison based-on it is performed. The need for high performance computing is emphasized. A general discussion how to improve the existing solutions or develop new ones in the future is also presented.


hSergey Leble and Maged Shaban An algorithm of velocity field evaluation via temperature field mesurement on the basis of streamline-defined coordinates

A new algorithm is presented for evaluating the velocity field of the heat convection flow from a vertical solid flat plate using the temperature field. Using the coordinate transformation of Cartesian coordinates, to coordinates defined via streamlines, and visible in such coordinate approximations, it is possible to express the basic flow fields in terms of the temperature gradients only. After discretization we formulate approximated sufficient finite-difference formulas to evaluate the velocity field using the experimental data.


hBeata Krawczyk-Bryłka Comparative Study of Traditional and Virtual Teams

The paper presents two kinds of cooperating teams: traditional and virtual, and proposes a new measure of the team virtuality level. Some representative teamwork characteristics, such as team member competencies, team diversity, leadership, and team decision-making are analyzed and compared depending on the degree of virtuality. Moreover, the team climate as one of the team performance measures is also analyzed and compared in virtual and traditional teamwork conditions. The considerations show that the virtuality level is crucial for virtual and face-to-face team comparison, virtual and hybrid team analysis and answering the question how to improve online collaboration processes and performance.


hThe Hung Tran and Szymon Winczewski Central-force decomposition of the Tersoff potential

Central forces play important role in the analysis of results obtained with particle simulation methods, since they allow evaluating stress fields. In this work we derive expressions for a central-force decompositon of the Tersoff potential, which is often used to describe interatomic interactions in covalently bonded materials. We simplify the obtained expressions and discuss their properties.


hSławomir Dykas, Mirosław Majkut, Krystian Smołka and Michał Strozik Assessment of the Capability of Available Methods of Flow Field Numerical Modelling on the Example of Air Flow through a Channel with a Circular Bump

This paper is an attempt at a systematic approach to the flow field analysis in the case of air flowing through a straight channel with a circular bump. The results of the authors' own experimental measurements are compared to those obtained by means of both an in-house and a commercial CFD code. Apart from the RANS method, which is commonly used in engineering applications, a decision was made to use the URANS and LES methods, which are available both in the in-house academic code and in the commercial program. The comparison between the calculation results is performed using what is referred to as the numerical Schlieren image, which for the RANS calculations is compared to the Schlieren image obtained from experimental testing.


The Current Issue