Faculty of Natural Sciences

Secure environment is top-priority for all the forms of grid computing. To establish trust, traditional grids use various methods, mostly central oriented ones, such as certification authorities, VO management servers or credentials pools. Ad hoc grid environment is characterized by the absence of a central trusted authority; therefore collaborating entities must establish and maintain a trust relationship among themselves. The paper presents a short overview of the ad hoc grid, the definitions as well as authentication and authorization mechanisms of the environment. We design a proposal of support authorization mechanism for faster and easier formation of virtual organizations in ad hoc grid based on SPKI delegation chains where the delegation chains act as trust chains, even if they do not refer to target users.

The aim of this work is the depth of the snow cover computing in the desired point based on the geographical characteristics of a specific geographical point in a modeled area. The measured data are known on few places. These places are coincident with raingauge stations. These data have been collected by many continuous observations and measurements at the specific climatologic raingauging stations of Slovak Hydrometeorogical Institute. An interpolation method is necessary to obtain a representation of real situation about whole surface. The main characteristic of the interpolation computing is the fact that it is timeconsuming. In paper, we present two cheap approaches of HPC. The first solution is a utilization of graphics processing units (GPUs) where the availability of enormous computational performance of easily programmable GPUs can rapidly decrease time of computing. The second one is a utilization of multi-thread CPUs. In our article we demonstrate how to deploy the CUDA architecture, which utilizes the powerful parallel computation capacity of GPU, to accelerate computational process of snow cover depth using the inversedistance weighting (IDW) method. The performance of GPU we face with OpenMP implementation of IDW method. We consider variable number of threads per CPU. The outputs are visualized by the GIS Grass tool.

Information security, and Cryptography as a part of it, is a critical topic for computer science students to understand. Different teaching approaches can be effective in helping the students understand abstract principles. In this paper, we present our approach to Cryptography education that is based on the idea that the stages of growth of the individual might recapitulate the stages of growth of the science. The Cryptography is apprehended as pilot model for further proposal of Computer Science education.

Trust in grid computing plays a significant role. Traditional grids use various methods for this, mostly centrally oriented ones, such as certification authorities, VO management servers or credentials pools. Ad hoc grids are characterized by absence of a central trust authority; therefore collaborating entities must establish and maintain a trust relationship among themselves. The paper presents a short overview of ad hoc grids and authorization mechanisms. We design a supported authorization mechanism for easier formation of virtual organizations based on VOMS certificates. The mechanism can facilitate the establishment of a trust relationship in cases when standard solutions have failed.

Trust is an integral part of grid computing systems. Traditional grid environment uses various, mostly centrally oriented methods for trust establishment, e.g. certification authorities, VO management servers or credentials pools. On the other side, ad hoc grids demand minimal administrative requirements; especially an absence of a central trust authority, where collaborating entities must establish and maintain a trust relationship among themselves. The paper presents a design of a supported authorization mechanism for easier formation of virtual organizations based on attribute certificates. Moreover, an evaluation of the mechanism based on simulation results as well as insights into the configuration of such scheme in ad hoc grid environment are described.

Abstract: The optimization of the irregular connection network of the multiprocessor systems with the distributed memory is the NP complete problem which is generally compute-intensive process. Graphics processing units provide a large computational power at a very low price allowing the fine-grained parallelism. This work investigates the use of the GPU in the parallelisation of the optimal irregular network configurations up to 128 processors.

This paper deals with parallelization of the Quine-McCluskey algorithm. This boolean function minimization algorithm has a limitation when dealing with more than four variables. The problem computed by this algorithm is NP-hard and runtime of the algorithm grows exponentially with the number of variables. The goal is to show that parallel implementation of the Quine-McCluskey algorithm on graphics processing units (GPUs) brings significant acceleration of computing process. Parallelization of the algorithm is implemented through Compute Unified Device Architecture (CUDA), which is a parallel computing platform and programming model created by NVIDIA and implemented by graphics processing units (GPUs).

This paper presents the solution of interpolating algorithm of snow cover computing
on different parallel computing architectures, eg cluster, graphics processing units (GPUs),
multi-core CPU Moreover, testing Algorithm was tested and deployed on grid technologies
connected toEGEE/Voce virtual organization utilizing high processing performance and
storage capacity. The comparison of performance of the computing is presented in the
article.

The OurGrid distributed environment is an open source grid middleware that
enables the creation of P2P computational grids to speed up the execution of bag-of-tasks
applications. Bag-of-tasks is an application model composed of several independent tasks
not communicating with each other during their execution, tolerating network delays and
faults. The paper shows that the main advantage to avoid bottlenecks is if the data gets
larger or computations become more complex and the conclusion is made based on the ...

In a short span of time, cloud computing has grown, particularly for commercial web
applications. But the cloud computing has the potential to become a greater instrument for
scientific computing as well. A pay-as-you-go model with minimal or no upfront costs creates
a flexible and cost-effective means to access compute resources. In this paper, we carry out
a study of the performance of the spatial data interpolation of depth of the snow cover on the
most widely used cloud infrastructure (Amazon Elastic Compute Cloud). The main ...

In this paper, we try to present the problems of the modern approach to treating various phobias. Virtual environments created by virtual reality (VR) tools can help to make the treatment of certain types of phobias more efficient. Attention to this form of phobia treatment with the help of VR is on the rise in the world, so we are also monitoring its development, as well. Our paper introduces the necessary hardware and software that has been piloted in our department, but also methods of creating virtual environments, models and application designed for medical therapies of patients. In ourworkwe have searched for and tested the following methods for creating virtual environments: A) modelling using computer graphics, B) modelling animation using animation programs, C) taking pictures of static objects and scenes, D) filming moving objects and scenes using classic video or special scanning techniques to create 360∘ panoramas or E) any combination of these methods.

Paleolimnological research in the territory of Slovakia has relatively short history with the beginning in the 1990s primarily as a response to the ecological changes in mountain lakes due to air pollution and missing data from the pre-industrial period as well as a need to quantify anthropic impact on the landscape. In the present paper, we reviewed 53 publications, including research papers, monographs, conference abstracts and theses, dealing with aquatic proxies in Holocene lake sediments to identify (1) the location of surveyed sites, (2) proxies used, and (3) the object of the paleolimnological reconstructions. The vast majority (37) of the analysed paleolimnological localities (51) took place in the High Tatra Mountains, focusing on the alpine lakes of glacial origin. The most frequently used biological proxy was Chironomidae remains (44%). In contrast, Cladocera, Ostracoda, loss-on-ignition, molluscs and stable isotopes were used only in 10–12% of studies. Most studies (84%)...