Computing and Informatics (E-Journal - Institute of Informatics, SAS, Bratislava)
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Algebraic Approach to Logical Inference Implementation
Get PDFThe paper examines the usage potential of n-tuple algebra (NTA) developed by the authors as a theoretical generalization of structures and methods applied in intelligence systems. NTA supports formalization of a wide set of logical problems (abductive and modified conclusions, modelling of graphs, semantic networks, expert rules, etc.). This article mostly describes implementation of logical inference by means of NTA. Logical inference procedures in NTA can include, besides the known logical calculus methods, new algebraic methods for checking correctness of a consequence or for finding corollaries to a given axiom system. Inference methods consider (above feasibility of certain substitutions) inner structure of knowledge to be processed, thus providing faster solving of standard logical analysis tasks. Matrix properties of NTA objects allow to decrease laboriousness of intellectual procedures as well as to efficiently parallel logical inference algorithms. In NTA, we discovered new structural and statistical classes of conjunctive normal forms whose satisfiability can be detected for polynomial time. Consequently, many algorithms whose complexity evaluation is theoretically high, e.g. exponential, can in practice be solved in polynomial time, on the average. As for making databases more intelligent, NTA can be considered an extension of relational algebra to knowledge processing. In the authors' opinion, NTA can become a methodological basis for creating knowledge processing languages
Compressed Skewed-Load Delay Test Generation Based on Evolution and Deterministic Initialization of Populations
Get PDFThe current design and manufacturing semiconductor technologies require to test the products against delay related defects. However, complex acpSOC require low-overhead testability methods to keep the test cost at an acceptable level. Skewed-load tests seem to be the appropriate way to test delay faults in these acpSOC because the test application requires only one storage element per scan cell. Compressed skewed-load test generator based on genetic algorithm is proposed for wrapper-based logic cores of acpSOC. Deterministic population initialization is used to ensure the highest achievable aclTDF coverage for the given wrapper and scan cell order. The developed method performs test data compression by generating test vectors containing already overlapped test vector pairs. The experimental results show high fault coverages, decreased test lengths and better scalability in comparison to recent methods
Energy Efficient Scheduling in Heterogeneous Systems with a Parallel Multiobjective Local Search
Get PDFThis article introduces ME-MLS, an efficient multithreading local search algorithm for solving the multiobjective scheduling problem in heterogeneous computing systems. We consider the minimization of both the makespan and energy consumption objectives. The proposed method follows a fully multiobjective approach, applying a Pareto-based dominance search that is executed in parallel by using several threads. The experimental analysis demonstrates that the new multithreading algorithm outperforms a set of fast and accurate two-phases deterministic heuristics based on the traditional MinMin. The new ME-MLS method is able to achieve significant improvements in both makespan and energy consumption objectives in reduced execution times for a large set of testbed instances, while exhibiting a near linear speedup behavior when using up to 24 threads
Educational Tools for Object-Oriented DSP Interactive DSL Framework
Get PDFThis paper presents DSP blocks which were developed to be used as basic elements for realization of the DSP algorithms. For this purpose the description DSL (Domain Specific Language) language was used. The goal of this paper is to define and present a high level language that allows description and development of signal processing algorithms. With the usage of a domain specific language, one can create a compact and easy to understand definition of algorithms. In the paper the authors present the advantages granted by DSL for DSP applications. The created definitions are hardware independent and they can be executed and functionally verified. Efficient code can be generated for various targets without porting. The design of the presented DSL allows code generation for multi-core targets in case of computing-intensive algorithms, code generation for multiple streams and threads. To validate the results these blocks were made available for use to students as an easy method for the introduction of the DSP algorithms in sound and image processing. The main purpose was for the students to gain some basic insight into elementary techniques needed for design, implementation and merging of hardware and software components used in testing of the algorithms for digital signal processing in real time. Through the work with the students it was concluded that the developed DSP blocks presented very good assistance in educational process and therefore this paper was elaborated on that idea. Since real hardware systems were used in this case noise was introduced in the system which does not exist in simulation software and therefore this option produced much larger capabilities for development of the robust algorithms
A Model to Overcome Integrity Challenges of an Untrusted DSMS Server
Get PDFDespite the fact that using the services of outsourced data stream servers has been welcomed extremely, still the problem of obtaining assurance about the received results from these untrusted servers in unsecure environment is one of the basic challenges. In this paper, we present a probabilistic model for auditing received results from an outsourced data stream server through unsecure communication channels. In our architecture, the server is considered as a black box and the auditing process is fulfilled by cooperation between the data stream owner and users. Our method imposes an ignorable overhead on the user and needs no change in the structure of the server. The probabilistic modeling of the system proves algorithms convergence and the experimental evaluations show very acceptable results
Securing Controls Middleware of the Large Hadron Collider
Get PDFThe distributed control system of the Large Hadron Collider (LHC) presents many challenges due to its inherent heterogeneity and highly dynamic nature. One critical challenge is providing access control guarantees within the middleware. Role-based access control (RBAC) is a good candidate to provide access control. However, in an equipment control system transactions are often dependent on user context and device context. Unfortunately, classic RBAC cannot be used to handle the above requirements. In this paper we present an extended role-based access control model called CMW-RBAC. This new model incorporates the advantages of role-based permission administration together with a fine-grained control of dynamic context attributes. We also propose a new technique called dynamic authorization that allows phased introduction of access control in large distributed systems. This paper also describes motivation of the project, requirements, and overview of its main components: authentication and authorization
A Cover-Merging-Based Algorithm for the Longest Increasing Subsequence in a Sliding Window Problem
Get PDFA longest increasing subsequence problem (LIS) is a well-known combinatorial problem with applications mainly in bioinformatics, where it is used in various projects on DNA sequences. Recently, a number of generalisations of this problem were proposed. One of them is to find an LIS among all fixed-size windows of the input sequence (LISW). We propose an algorithm for the LISW problem based on cover representation of the sequence that outperforms the existing methods for some class of the input sequences
Semantic-Based Storage QoS Management Methodology -- Case Study for Distributed Environments
Get PDFThe distributed computing environments, e.g. clouds, often deal with huge amounts of data, which constantly increase. The global growth of data is caused by ubiquitous personal devices, enterprise and scientific applications, etc. As the size of data grows new challenges are emerging in the context of storage management. Modern data and storage resource management systems need to face wide range of problems -- minimizing energy consumption (green data centers), optimizing resource usage, throughput and capacity, data availability, security and legal issues, scalability. In addition users or their applications can have QoS (Quality of Service) requirements concerning the storage access, which further complicates the management. To cope with this problem a common mass storage system model taking into account the performance aspects of a storage system becomes a necessity. The model described with semantic technologies brings a semantic interoperability between the system components. In this paper we describe our approach at data management with QoS based on the developed models as a case study for distributed environments
Variable Precision Rough Set Model for Incomplete Information Systems and Its Beta-Reducts
Get PDFAs the original rough set model is quite sensitive to noisy data, Ziarko proposed the variable precision rough set (VPRS) model to deal with noisy data and uncertain information. This model allowed for some degree of uncertainty and misclassification in the mining process. In this paper, the variable precision rough set model for an incomplete information system is proposed by combining the VPRS model and incomplete information system, and the beta-lower and beta-upper approximations are defined. Considering that classical VPRS model lacks a feasible method to determine the precision parameter beta when calculating the beta-reducts, we present an approach to determine the parameter beta. Then, by calculating discernibility matrix and discernibility functions based on beta-lower approximation, the beta-reducts and the generalized decision rules are obtained. Finally, a concrete example is given to explain the validity and practicability of beta-reducts which is proposed in this paper
nMIBAS: A Novel Multi-Receiver ID-Based Anonymous Signcryption with Decryption Fairness
Get PDFBased on the ring signature technology, the multi-receiver ID-based anonymous signcryption (MIBAS) is proposed, and its goal is to protect the privacy of the sender or so-called signer. In an MIBAS scheme, every receiver can verify whether the sender is a member of a trusted group and thus ensure the reliability of the message source, but he could not get the real sender. However, MIBAS paid no attention to privacy of the receivers and has not taken the privacy of the receivers into account during its design. Our analyses show that there widely exist the receiver privacy exposure and decryption unfairness problems in the existing multi-receiver ID-based signcryption schemes. Motivated by these concerns, a new multi-receiver ID-based anonymous signcryption (nMIBAS) is proposed to protect the identity of the receivers. The nMIBAS scheme can not only solve the problem that the existing schemes cannot protect the privacy of receivers, but also meet the fairness of decryption to prevent the possible cheating behavior of the sender effectively. Analysis shows that this scheme is a secure and effective signcryption scheme