Computer Science Journal (AGH University of Science and Technology, Krakow)
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Application of projection-based interpolation algorithm for non-stationary problem
Get PDFIn this paper we present a solver for non-stationary problems using L2 projection and h-adaptations. The solver utilizes the Euler time integration scheme for time evolution mixed with the projection based interpolation techniques for solving the L2 projections problem at every time step. The solver is tested on the model problem of the heat transfer in L-shape domain. We show that our solver delivers linear computational cost at every time step
Quality of Experience in the context of mobile applications
Get PDFMobile devices are among the most-popular means of browsing the Internet, sending and receiving e-mail, and sharing content on social networks. People use mobile devices and the applications installed on them in different situations throughout the day. In order to ensure that users are satisfied with a mobile application, its author has to ensure a high Quality of Experience level. The problem of automatic evaluation of the QoE parameter is a very interesting research area. Quality of Experience is a broad issue and requires the analysis of many aspects not only graphical user interfaces but also, inter alia, Quality of Service and user ratings
Source code reviews on mobile devices
Get PDFThis paper presents the results of an experiment-driven investigation on the efficiency of source code review practice performed on mobile devices. In particular, the conducted investigation tries to verify whether or not the small screens of mobile devices influence the speed and quality of the review process. Besides presenting the experiment itself and discussing the obtained results, this paper also describes the dedicated Android application for mobile code reviews that was implemented for research purposes
Building sentiment lexicons based on recommending services for the Polish language
Get PDFSentiment analysis has become a prominent area of research in computer science. It has numerous practical applications; e.g., evaluating customer satisfaction, identifying product promoters. Many methods employed in this task require language resources such as sentiment lexicons, which are unavailable for the Polish language. Such lexicons contain words annotated with their emotional polarization, but the manual creation of sentiment lexicons is very tedious. Therefore, this paper addresses this issue and describes a new method of building sentiment lexicons automatically based on recommending services. Next, the built lexicons were used in the task of sentiment classification
Implementing graph representation model for parallel and distributed systems using Erlang
Get PDFThis paper describes a new model of graph representation using the Erlang actor model. Benefits of using lightweight processes instead of traditional passive data structures are given. Examples of using this model are shown. The experimental part gives two examples of using early implementations of the offered model. As a conclusion, an analysis of applicability for tasks from different branches of science is given
A NOVEL ADAPTIVE CHECKPOINTING METHOD BASED ON INFORMATION OBTAINED FROM WORKFLOW STRUCTURE
Get PDFScientific workflows are data- and compute-intensive; thus, they may run for days or even weeks on parallel and distributed infrastructures such as grids, supercomputers, and clouds. In these high-performance computing infrastructures, the number of failures that can arise during scientific-workflow enactment can be high, so the use of fault-tolerance techniques is unavoidable. The most-frequently used fault-tolerance technique is taking checkpoints from time to time; when failure is detected, the last consistent state is restored. One of the most-critical factors that has great impact on the effectiveness of the checkpointing method is the checkpointing interval. In this work, we propose a Static (Wsb) and an Adaptive (AWsb) Workflow Structure Based checkpointing algorithm. Our results showed that, compared to the optimal checkpointing strategy, the static algorithm may decrease the checkpointing overhead by as much as 33% without affecting the total processing time of workflow execution. The adaptive algorithm may further decrease this overhead while keeping the overall processing time at its necessary minimum
Adapting a Constituency Parser to User-Generated Content in Polish Opinion Mining
Get PDFThe paper focuses on the adjustment of NLP tools for Polish; e.g., morphological analyzers and parsers, to user-generated content (UGC). The authors discuss two rule-based techniques applied to improve their efficiency: pre-processing (text normalization) and parser adaptation (modified segmentation and parsing rules). A new solution to handle OOVs based on inflectional translation is also offered
Statistical models to accelerate software development by means of iterative compilation
Get PDFMinimization of data-processing time and reduction of software-development time are important practical problems to be tackled by modern computer science.This paper presents the authors\u27 proposal of a family of statistical models for the estimation of program execution time, which is an approach focused on both of the above problems at the same time. The family consists of a general model and specific models and has been elaborated based on empirical data collected for pattern-program loops representing some arbitrarily selected features related to the program structure and the specificity of a program-execution environment.The paper presents steps to elaborate the aforementioned family as well as the results of the carried-out experimental research. The paper demonstrates how the elaborated models can be applied in iterative compilation for optimization purposes, allowing us to reduce the time of software development and produce code with minimal execution time
Hybrid computer system for the identification of metallic material models on the basis of laboratory experiments
Get PDFThe identification of the proper parameters of material models plays a crucial role in the design of production technologies, especially in the case of modern materials with diversified properties under different boundary conditions. The procedure of identification is usually based on an optimization algorithm that uses sophisticated numerical simulations as a part of the goal function and compares the obtained results with experimental tests. Despite its reliability, such an approach is numerically inefficient. This paper presents the concept of how to replace the most numerically-demanding part of the identification procedure with metamodels, allowing us to maintain uniform result quality. The computer system, which allows us to manage input data, metamodels, and calculations, is proposed and described in detail in this paper. Finally, the proposed approach is validated on the basis of tests performed in the laboratory
Parallel Patterns for Agent-based Evolutionary Computing
Get PDFComputing applications such as metaheuristics-based optimization can greatly benefit from multi-core architectures available on modern supercomputers. In this paper, we describe an easy and efficient way to implement certain population-based algorithms (in the discussed case, multi-agent computing system) on such runtime environments. Our solution is based on an Erlang software library which implements dedicated parallel patterns. We provide technological details on our approach and discuss experimental results