Computing and Informatics (E-Journal - Institute of Informatics, SAS, Bratislava)
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Enhanced Methodology for Ontology Development
Get PDFThe creation of an initial glossary of terms is a preliminary phase of domain ontology building. Existing methodologies assume that such a glossary has been created by analysing existing documents or using expert knowledge. Some methods have been defined for this step of ontology building; these methods are mostly based on the analysis of existing documents. We propose to utilise the existing pieces of knowledge obtained in the area of object-oriented analysis; the description of a domain structure, behaviour and rules. Domain structure, behaviour and rules all together represent a complex and systematic view of the domain that makes it possible to create a high-quality glossary. This method is demonstrated using the domain of a road traffic system. Our method has been developed as an extension of the well-known METHONTOLOGY method. Our extension is general enough to be relevant for other ontology-building methodologies
A New Linear-Time Dynamic Dictionary Matching Algorithm
Get PDFThis research presents inverted lists as a new data structure for the dynamic dictionary matching algorithm. The inverted lists structure, which derives from the inverted index, is implemented by the perfect hashing table. The dictionary is constructed in optimal time and the individual patterns can be updated in minimal time. The searching phase scans the given text in a single pass, even in a worst case scenario. In experimental results, the inverted lists used less time and space than the traditional structures; the searches were processed and showed an efficient linear time
A Statistical Approach for the Maximization of the Financial Benefits Yielded by a Large Set of MMFs and AEs
Get PDFThis article introduces a statistical approach for the maximization of the financial benefits yielded by software projects that have been broken down into a considerable number of minimum marketable features modules (MMFs) and architectural elements (AEs). As the statistical approach requires a polynomial computational effort to run and provides approximation solutions with an arbitrarily chosen degree of confidence, it allows managers and developers to be more confident about the rightness of the decisions they make with little additional computational effort
HMS: A Hierarchical Mapping System for the Locator/ID Separation Network
Get PDFThe current Internet is facing serious scalability problems and the overloading of Internet Protocol (IP) addresses is regarded as an important reason. The Locator/ID Separation Protocol (LISP) is proposed as a network-based solution that separates IP addresses into Routing Locators (RLOCs) and Endpoint Identifiers (EIDs) to address the routing scalability problems. It is a critical challenge for LISP to design a scalable and efficient mapping system. In this paper, we propose a hierarchical mapping system (HMS). HMS consists of two levels with the bottom level maintaining the EID-to-RLOC mappings in an Autonomous System (AS) and the upper level storing the mappings between EID-prefixes and ASs in the global network. We adopt one-hop Distributed Hash Table (DHT) to organize EID-to-RLOC mappings in the bottom level and use a protocol like Border Gateway Protocol (BGP) to propagate EID-prefix-to-AS mappings in the upper level. HMS aggregates the prefixes in an AS and decreases the global mapping entries in the upper level. The evaluation results show that the number of mapping entries in HMS grows slower than the routing table size, which makes HMS scalable. In addition, the mobility in HMS does not cause mapping changes in the upper level. It makes HMS efficient in supporting host mobility. We estimate the map-requests sent to the mapping system, which show the load on HMS is small. Last, we compare HMS with LISP-TREE and LISP+ALT by quantitative analysis, in terms of resolution cost, and qualitative analysis. The results show that HMS has a good performance
A Needle in the Haystack: Higgs Boson Searches in the ATLAS Experiment
Get PDFA preliminary combination of Standard Model Higgs searches with the ATLAS experiment, in a dataset collected at energy sqrt(s) = 7 TeV at the LHC in year 2011, is presented. The paper refers to the status of Higgs boson searches as from March 2012, before the Higgs discovery at LHC. The Higgs boson mass ranges from 112.7 GeV to 115.5 GeV, 131 GeV to 237 GeV and 251 GeV to 468 GeV are excluded at the 95 % confidence level. An excess of events is observed for a Higgs boson mass hypothesis close to 126 GeV. This successful analysis was possible due to the excellent performance of the GRID distributed computing system, in which two Polish sites ACK Cyfronet from Krakow and PSNC from Poznan have participated. The ATLAS analysis chain and the usage of grid for ATLAS data processing are described in this paper
Research on Tracking and Synchronization of Uncertain Chaotic Systems
Get PDFThe tracking and synchronization problem of uncertain chaotic system, which is considered to be applied in secure communication in the future by many researchers, is considered in this paper. A double integral sliding mode controller is adopted to cope with the uncertainties of the chaotic system. Adaptive and robust strategies, such as Nussbaum gain method, are used to solve the unmodeled dynamic problem and unknown control direction problem. Meanwhile, the stability of the whole system is guaranteed by constructing of a big Lyapunov function for the whole system. Finally, a four dimension super-chaotic system is used as an example to do the numerical simulation and it testifies the rightness and effectiveness of the proposed method
Robust Fixed Point Transformations-based Control of Chaotic Systems
Get PDFNowadays, nonlinear control is a very important task because machines are playing more and more role in life. Lyapunov's 2nd method is a popular tool by the use of which various controllers can be designed like the adaptive Neural Networks, Fuzzy Controllers, and Neuro-Fuzzy solutions, or the Sliding Mode Controllers and the well-known PID feedback controllers. Robust Fixed Point Transformation is a procedure which can be built for almost any type of controller in case an approximate model is used to estimate the controlled system's behavior. In this paper a new approach to Robust Fixed Point Transformations (RFPT) is introduced by integrating a second controller in the system. Authors show that this additional, "recalculated" controller not just improves the original controller's results, but halves the tracking errors achieved by the previous RFPT methods
Depth-First Event Ordering in BDD-Based Fault Tree Analysis
Get PDFIn BDD-based fault tree analysis, the size of BDD encoding fault trees heavily depends on the chosen ordering. From a theoretical point of view, finding the best ordering is an intractable task. So, heuristics are used to get good orderings. The most simple, and often one of the best heuristics is depth first left most (DFLM) heuristic. Although having been used widely, the performance of DFLM heuristic is still only vaguely understood, and not much formal work has been done. This paper starts from two different research objects: fault tree without repeated events (NRFT) and fault tree with repeated events (RFT). For NRFT, the BDD generated according to DFLM ordering is proved to be the smallest BDD with the size equal to the total number of events. For RFT, a randomized algorithm is firstly proposed to create reliable benchmarks including large number of random fault trees with different specificities. Then, these benchmarks are used to perform two types of experiments to study the performance of DFLM heuristic. For RFT with small number of repeated events, it is found that the sizes of the BDD built over DFLM orderings are only slightly larger than the sizes of the RFT with different specificities. However, with the increase of the number of repeated events, we encounter the size explosion problem, and the change of repeated event distribution patterns will have a significant impact on the sizes of the BDD built over DFLM orderings. We also find that the number of repeated events is the more important measure than some other specificities (shape, logical type of top gate and OR/AND gate distribution) to estimate the level of the difficulty in BDD-based fault tree analysis
Decomposable Naive Bayes Classifier for Partitioned Data
Get PDFMost learning algorithms are designed to work on a single dataset. However, with the growth of networks, data is increasingly distributed over many databases in many different geographical sites. These databases cannot be moved to other network sites due to security, size, privacy, or data ownership consideration. In this paper, we propose two decomposable versions of Naive Bayes Classifier for horizontally and vertically partitioned data. The goal of our algorithms is to achieve the learning objectives for any data distribution encountered across the network by exchanging minimum local summaries among the participating sites
Semantic Web Service Engineering: Annotation Based Approach
Get PDFWeb services are an emerging paradigm which aims at implementing software components in the Web. They are based on syntactic standards, notably WSDL. Semantic annotation of Web services provides better qualitative and scalable solutions to the areas of service interoperation, service discovery, service composition and process orchestration. Manual annotation is a time-consuming process which requires deep domain knowledge and consistency of interpretation within annotation teams. Therefore, we propose an approach for semi-automatically annotating WSDL Web services descriptions. This is allowed by Semantic Web Service Engineering. The annotation approach consists of two main processes: categorization and matching. Categorization process consists in classifying WSDL service description to its corresponding domain. Matching process consists in mapping WSDL entities to pre-existing domain ontology. Both categorization and matching rely on ontology matching techniques. A tool has been developed and some experiments have been carried out to evaluate the proposed approach