Jacek Kitowski

Grid organizational memory-provision of a high-level Grid abstraction layer supported by ontology alignment

In this paper the problem of managing ontological descriptions for a dynamically-changing Grid environment is addressed. The focus of the research is on unification of semantic descriptions for Grid services and resources through ontologies. The Grid Organizational Memory (GOM) has been designed and implemented to enable storing and accessing Grid metadata, kept in the form of ontologies. In GOM, ontology storage and management are designed to support the natural evolution process both in the knowledge structure and knowledge management services. An important element of the GOM framework is the ontology separation schema, specifying the internal vertical and horizontal dependencies according to the Virtual Organization thematic domains, efficiency of knowledge retrieval and ontology development support. The separation schema is applied in the knowledge base distribution model on the Grid. An ontology alignment-based approach is proposed to minimize user commitment on the Grid ontological metadata, to support ontology usage and development. In particular the ontology similarity based approach is presented as support for ontology updates, e.g. extension with new facts from external ontologies and environments, as well as a more efficient and complete, less implementation-bounded querying process. This paper presents research on semantic description of the Grid environment within the scope of the K-Wf Grid project that addresses knowledge-based semiautomatic workflow construction for applications on the Grid.

Diagnostics of faulty states in complex physical systems using fuzzy relational equations

ABSTRACT The paper presents a method for diagnostics of physical system failures based on the fuzzy relational equation with the max-mm composition. The heuristic algorithm for inverse problem solving is briefly described. Since proper description of the plant properties is significant to increase efficiency of the diagnostics two versions of the relationship matrix extension are proposed. The first one considers different directions of failure and symptom deviations from their nominal values. The second one deals with on-line extensions of the relationship matrix in a case of unexpected failure occurrence. Finally the diagnostic system with some elements of fuzzy logic is discussed in order to improve man-machine communications. For test purposes the systems have been applied for failure analysis of the THTR-300 nuclear power plant modelled by a computer code.

Translation of Common Information Model to Web Ontology Language

This paper presents a brief overview of the work on translation of Common Information Model (CIM) to Web Ontology Language (OWL) standard. The main motivation for the work is given, along with discussion of major issues faced during this work. The paper contains also comparison of existing approaches to conversion of CIM to OWL and presents the CIM2OWL tool that performs the conversion of CIM schema and allows convertion of CIM instances - representing for instance configurations of particular systems - to OWL individuals.

Complex fluid-dynamical phenomena modeled by large-scale molecular-dynamics simulations

We carried out large-scale molecular-dynamics simulations of the classical Rayleigh–Taylor (RT) phenomenon in a Lennard-Jones molecular liquid. We have observed from these simulations, involving 106–107 particles, the development of hydrodynamic instabilities from two different kinds of interacting particles. A free surface is introduced by deploying an overlying void. For a box with a dimension up to about 1 μm and two layers having different particle sizes, the fingering type of instability is observed as a result of oscillations caused by the gravitational field. In this gridless scheme, surface waves can be captured self-consistently. For equally sized particles, a spontaneous “fluctuation driven” mixing with a long start-up time is observed. These molecular- dynamics results suggest the possibilities of upscaling the RT phenomenon. For conducting these numerical experiments, which require at least ∼105 time steps, a single simulation would require 100–200 Tflops of massively parallel computer power. ...

Access cost estimation for unified grid storage systems

In typical data grids large amounts of replicated data are stored all over the globe in different storage systems with access latencies ranging from seconds to hours. The task of a replica management system is not only to keep track of the replicas but also to select those replicas that can be accessed by an application program with a minimal response or transfer time. Most wide-area replication research focuses on network-based replica selection. However, our past experience with data grids has shown that often hierarchical storage systems are the main bottleneck rather than network links. This is due to the fact that access latencies of hierarchical storage systems can be of the order of seconds up to hours in case the data resides on a tape that is not mounted yet. We give an overview of our replica management framework called Reptor and a storage system cost estimator that is used. Furthermore, we give details on access estimation of file replicas that reside on hierarchical storage systems. The results show that the access estimates provide a good basis for a replica management system to perform efficient replica selection.

PL-Grid: foundations and perspectives of national computing infrastructure

The Polish Grid Initiative commenced in 2009 as part of the PL-Grid project funded within the framework of the Innovative Economy Operational Programme. The main objective is to provision a persistent heterogeneous computational platform for the Polish scientific community with a unified interface, enabling easy access to the distributed large-scale computing infrastructure. The project establishes a countrywide computing platform which supports scientific research through integration of experimental data and results of advanced computer simulations carried out by geographically distributed computer infrastructure and teams. The solutions applied in setting up this e-infrastructure facilitate integration with other, similar platforms around the world. In this chapter the foundations of the PL-Grid architecture, a brief history of the project and its most important objectives are presented.

Agent-Based simulation platform evaluation in the context of human behavior modeling

In this paper we provide a brief survey of agent based simulation (ABS) platforms and evaluate two of them --- NetLogo and MASON --- by implementing an exemplary scenario in the context of human behavior modeling. We define twelve evaluation points, which we discuss for both of the evaluated systems. The purpose of our evaluation is to identify the best ABS platform for parametric studies (data farming) of human behavior, but we intend to use the system also for training purposes. That is why we also discuss one of serious game platform representatives --- VBS2.

Implementation of replication methods in the grid environment

Data replication methods are often used in Grid environments for improving the access time and data protection level. Dynamic replication allows the system to automatically create and delete replicas in order to follow dynamically changing system parameters and user access patterns keeping the performance high and resource usage in reasonable limits. In this paper we present the replication aspects of the Virtual Storage System developed within one of the grid projects. We also present results from replication tests done in a real grid environment.

Self-scalable services in service oriented software for cost-effective data farming

Abstract Software maintenance is one of the major concerns in service oriented ecosystem with an ever-increasing importance. In many cases, the cost of software maintenance is higher than the cost of software development. In particular, long-lasting services, which operate in a dynamically changing environment, require continuous management and administration. One of the important administration actions is scaling management. The problem lies in responding to workload changes of the hosted services as fast as possible. This is especially important in regard to (but not limited to) cloud environments where unnecessary resource usage leads to unnecessary costs. In this paper, we are introducing the self-scalable services and scaling rules, which are intended to support development of self-scalable systems based on Service Oriented Architecture. We propose a design of a self-scalable service based on some of the well-known software development practices along with a definition of scaling rules, which express scaling policy for the service. Both concepts were evaluated in the context of a massively scalable platform for data farming. The evaluation demonstrates advantages of utilizing the proposed concepts to manage the platform in comparison with traditional platform management strategies based on fulfilling peak load.

Dynamic VO Establishment in Distributed Heterogeneous Business Environments

As modern SOA and Grid infrastructures are being moved from academic and research environments to more challenging business and commercial applications, such issue as control of resource sharing become of crucial importance. In order to manage and share resources within distributed environments the idea of Virtual Organizations (VO) emerged, which enables sharing only subsets of resources among partners of such a VO within potentially larger settings. This paper describes the Framework for Intelligent Virtual Organizations (FiVO), focusing on its functionality of enforcing security (Authentication and Authorization) in dynamically deployed Virtual Organizations. The paper presents the overall architecture of the framework along with different security settings which FiVO can support within one Virtual Organization.