Vol. 35 · No. 2

Conventional utilization-based power model is effective for measuring the power consumption of physical machines. However, in virtualized environments its accuracy cannot be guaranteed because of the recursive resource accessing among multiple virtual machines. In this paper, we present a novel virtual machine scheduling algorithm, which uses Performance-Monitor-Counter as heuristic information to compensate the recursive power consumption. Theoretical analysis indicates that the error of virtual machine power model can be quantitative bounded when using the proposed scheduling algorithm. Extensive experiments based on standard benchmarks show that the error of virtual machine power measurements can be significantly reduced comparing with the classic credit-based scheduling algorithm.

Availability and performance are key issues in SOA cloud applications. Those applications can be represented as a graph spanning multiple Cloud and on-premises environments, forming a very complex computing system that supports increasing numbers and types of users, business transactions, and usage scenarios. In order to rapidly find, predict, and proactively prevent root causes of issues, such as performance degradations and runtime errors, we developed a monitoring solution which is able to elicit the end-to-end behavior of those applications. We insert lightweight components into SOA frameworks and clients thereby keeping the monitoring impact minimal. Monitoring data collected from call chains is used to assist in issues related to performance, errors and alerts, as well as business and IT transactions.

The contemporary large scale measuring systems in the real-time environment make extensive use of histogramming as a tool for the experimental data quality monitoring. The processing of a large number of data channels requires a suitable computing power where the graphical processors seem to be well suited. Histogramming operations run on the central and graphics processing units are discussed. Results of the performance measurements including various configurations of the allocation of the histograms in various parts of the memory of used devices are presented.

The software development approach called model-driven engineering has become increasingly widespread. The continuous integration practice has also been gaining the importance. Some works have shown that both can improve the software development process. The problem is that the model-driven engineering is still a very active research topic lacking its maturity, what translates into difficulties in optimal incorporation of the continuous integration practice in the process. We present an experience report in which we show the problems we have detected in a real project and how we have solved them. Thus, we increase the productivity of development and the non-technical people are able to modify already deployed applications. Finally, we incorporate an evaluation that shows the benefits of the proposed union.

Modeling timing constraints of distributed systems and multi-clock electronic systems aims to describe different time requirements aspects at a higher abstraction level. An important aspect is the logical time of the behavior of these systems. To model the time requirements, a specification language with multiple clock domains called Clock Constraint Specification Language (CCSL) has been introduced, in order to enrich the formalisms of existing modeling tools and also to facilitate the description and analysis of temporal constraints. Once the software has been modeled, the difficulty lies in both expressing the relevant properties and verifying them formally. For that purpose formal transformation techniques must be introduced. However, it remains difficult to exploit initial models as such, and to integrate them into a formal verification process. This paper introduces a methodology and the original tool chain for exploiting UML MARTE models enriched with CCSL specification. These will be integrated together with a range of tools for expressing and verifying time constraints. We propose a more general translation approach that verifies not only CCSL constraints implementations but also properties of the complete model including all the functional components. We evaluate our approach with a case study.

In large-scale grid environments, accurate failure prediction is critical to achieve effective resource allocation while assuring specified QoS levels, such as reliability. Traditional methods, such as statistical estimation techniques, can be considered to predict the reliability of resources. However, naive statistical methods often ignore critical characteristic behavior of the resources. In particular, periodic behaviors of grid resources are not captured well by statistical methods. In this paper, we present an alternative mechanism for failure prediction. In our approach, the periodic pattern of resource failures are determined and actively exploited for resource allocation with better QoS guarantees. The proposed scheme is evaluated under a realistic simulation environment of computational grids. The availability of computing resources are simulated according to real trace that was collected from our large-scale monitoring experiment on campus computers. Our evaluation results show that the proposed approach enables significantly higher resource scheduling effectiveness under a variety of workloads compared to baseline approaches.

Biclustering, which is simultaneous clustering of columns and rows in data matrix, became an issue when classical clustering algorithms proved not to be good enough to detect similar expressions of genes under subset of conditions. Biclustering algorithms may be also applied to different datasets, such as medical, economical, social networks etc. In this article we explain the concept beneath hybrid biclustering algorithms and present details of propagation-based biclustering, a novel approach for extracting inclusion-maximal gene expression motifs conserved in gene microarray data. We prove that this approach may successfully compete with other well-recognized biclustering algorithms.

UML-B is a graphical formal modelling notation which is based on UML and relies on Event-B and its verification tools. In this paper, we propose annealing and introduce subtyping rules as well-known refactoring rules which can improve and assist the derivation of object-oriented design from an abstract specification written in UML-B. We prove that the proposed annealing rules are behavior preserving. We also demonstrate the applicability and effectiveness of our refactoring rules by applying them on two UML-B specifications.

The paper presents an attempt to automate all data creation processes of a rule-based shallow-transfer machine translation system. The presented methods were tested on four fully functional translation systems covering language pairs: Slovenian paired with Serbian, Czech, English and Estonian language. An extensive range of evaluation tests was performed to assess the applicability of the methods.

The paper is concerned with safety appraisal of safety-related communication systems (SRComSs) with open transmission system, where except in addition to message transmission integrity also confidentiality is recommended to be provided. The authors focused on safety analysis of safety-related messages transmission secured using cryptographic and safety code mechanisms and on the possibilities of modelling safety-related industrial communication system, where a high safety integrity level SIL3 is required to be guaranteed. The paper features mathematical procedures to calculate the rate of hazardous transmission failure of safety-related messages in the result of electromagnetic interference (EMI) effects in the communication channel and by the presence of random hardware failures of SRComS. The theoretical techniques and safety analyses emerge from risk analysis and are compared with the knowledge gained by the authors during safety verifications of such systems for transportation applications. It is a little explored area, because the standards concerning safety-related control systems (SRCSs) did not support any cryptography-based methods. A quantitative safety integrity analysis of SRComS is based on utilisation of Markov's processes. The proposed Markov's model is applied on an open transmission system built on the IEEE 802.11g standard, which is complemented by cryptographic and safety code. The calculations are performed using Mathematica software tool. The proposed base model is universal and can be modified (simplified) in dependence on the parameters of a specific SRComS.