Computer Science Journal (AGH University of Science and Technology, Krakow)
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TIME EXTENSIONS OF PETRI NETS FOR MODELLING AND YERIFICATION OF HARD REAL-TIME SYSTEMS
Get PDFThe main aim ofthepaper is apresentation oftime extensions ofPetri nets appropriate for modelling and analysis o f hard real-time systems. It is assumed, that the extensions must provide a model o f time flow, an ability to force a transition to fire within a stated timing constraint (the so-called the strongfiring rule), and timing constraints represented by inte- rvals. The presented survey includes extensions o f classical Place/Transition Petri nets, as well as the ones applied to high-level Petri nets. An expressiveness o f each time extension is illustrated using simple hard real-time system. The paper includes also a brief description o f analysis and verification methods related to the extensions, and a survey o f software tools supporting modelling and analysis o f the considered Petri nets
Exploring Impact of Requirements Engineering on Other IT Project Areas – Case Study
Get PDFRequirements Engineering (RE) is recognized as one of the most important (yet difficult) areas of software engineering that has a significant impact on other areas of IT projects and their final outcomes. Empirical studies investigating this impact are hard to conduct, mainly due to the great effort required. It is thus difficult for both researchers and industry practitioners to make evidence-based evaluations about how decisions about RE practices translate into requirement quality and influence other project areas. We propose an idea of a lightweight approach utilizing widely-used tools to enable such an evaluation without extensive effort. This is illustrated with a pilot study where the data from six industrial projects from a single organization were analyzed and three metrics regarding the requirement quality, rework effort, and testing were used to demonstrate the impact of different RE techniques. We also discuss the factors that are important for enabling the broader adoption of the proposed approach
Computer Animation Basedon Particie Method
No full textThe article presents a program for animating the system of interacting flexible macroscopic objects and a liquid medium. Three-dimensional animation is carried out based on the simulation of physical phenomena. Its main task is faithful rendering of the dynamics of the objects present in the animation. Visualization is an important element of the animation program, but it has been significantly simplified by transferring its basic tasks (covering and shading) to graphic libraries. The simulation techniques used (particle and cellular automata method), detection and collision handling of objects were presented. In order to obtain faster animations, the program has also been implemented in a distributed version on a UNIX network of workstations
Optimistic and Pessimistic Result of Planning and Scheduling Dynamie Processes
Get PDFIn many real-life circumstances decision problems arise. Optimisation problems can be for- mulated as decision problems as well. An optimisation problem can be expressed in terms of a model and a performance index. While the model describes the problem, the perfor mance index assigns a value to each feasible realisation of the problem [1],An algorithm is a method to solve a class of problems with Computer. The computational complexity of an algorithm, which can be measured, is the cost. It is measured in runtime during which the algorithm is used to solve one of the problems. If the runtime is limited by a polynomial function of the amount of input data at most, the problem is said to be an easy one otherwise it is a hard problem. If a problem is easy it is enough to describe a method meeting such a constraint, when used to solve the problem. What does it mean that a problem is hard? The problem is hard when it is necessary to prove that it is impossible to find a fast method to perform the calculations which identify an optimal solution. There are a number of easy problems. Matrix inversion is easy: n * n matrix can be inverted with the Gaussian elimination method in time of cn at most. Sorting problem is easy as well. The fact that a computational problem is hard does not imply that its every instance has to be hard. The problem is hard when no algorithm can be pointed at, which could ensure a high performance for all instances of the problem. Notice that the amount of input data to the Computer in this example is smali [7].In recent years there has been a growth in research which deals with the development and complexity analysis of combinatorial algorithms. Complexity measures are of two kinds: static, independent of the size and characteristics of the input data, and dynamie, dependent on the input data [3]
USING THE I2C INTERFACE AND LOCALIZATION INFORMATION TO ACHIEVE PERSONALIZATION OF A DEVICE OPERATION
No full textThe article refers to the part of the hardware and software research which concems the problem of personalization of a common used device operation. The proposed solution is bascd on the ABS system (Activc Badge System) developed by ORL (OUvetti research Laboratories) in the United Kingdom, which delivers localization and identification information, and the universal communication interface I2C (Inter Integrated Circuit) developed by PHILIPS. The two abovc mentioned elements were used to create both the system of the automatic video signal flow con- trol and the system to identify a TV program being currently viewe
GENERATION OF TRIANGULAR MESHES FOR COMPLEX DOMAINS ON THE PLANE
Get PDFMany physical phenomena can bc modelcd by partial diffcrcntial cąuations. The dcvclopmcnt of numcrical methods bascd on the spatial subdivision of a domain into fmitc clcmcnts immcdiatcly cxtcnded interests to the tasks of generating a mesh. With the availability of vcrsatilc field solv- crs and powerful computcrs, the simulations of cver inereasing gcometrical and physical com- plcxity arc attempted. At somc point the main bottleneck becomcs the mesh generation itsclf.The papcr prcsents a dctailcd description of the triangular mcsh gcneration schcmc on the piane bascd upon the Dclaunay triangulation. A mcsh generator should be fully automatic and simplify input data as much as possible. It should offer rapid gradation from smali to large sizes of elcmcnts. The generated mcsh must be always valid and of good quality. Ali thesc rcquiremcnts were taken into account during the selection and elaboration of utilized algorithms.Successive chapters describe procedures connected with the specification of a modeled domain, gcneration and triangulation of boundary vertices, introducing inner nodes, improving the quality of the crcated mcsh, and renumbering of vertices
Methods of the Straightening Transformation and Analysis of Outer Contours of Objects in Medical Image Recognitio
No full textOne of the most important problems appearing in computer systems for the recognition and analysis of medical images, supporting diagnostics and medical therapy, is the processing of obtained images or their series in such a way that it is possible to unambiguously determine the disease symptoms occurring in them. Based on the detected symptoms, it is then possible to identify various disease entities, which in turn is the starting point for planning further therapy. Characterizing the process of automatic medical diagnostics, it can be stated that information in computer diagnostic systems can come from data on the occurrence of disease symptoms obtained during the analysis of medical images thanks to the use of various methods of artificial intelligence. Where subjected to recognition there are images on which any morphological changes of any of the organs can be observed, i.e. in the recognition of diseases visible on images obtained by various computed tomography techniques or radiographic images (e.g. ERCP, angiograms), the purpose of analyzing such images is to identify and unequivocal recognition of such morphological changes occurring in the examined organ. To this end, syntactic image recognition methods are often used. However, before proceeding to the proper extraction of the sought-after features that indicate the occurrence of disease symptoms, it is usually necessary to pre-process the analyzed photos so as to improve their quality, remove unnecessary (from the point of view of the diagnosis made) details while separating the recognized objec
LOOKING IN THE n-DIMENSIONAL SPACE
No full textThe possibility of looking at the cxterior appearancc of the n-dimensional solids using the cyc- sight is introduccd in this article. The dcvcloped mathematical model allows to creatc the Com puter program that makes looking at any solid having any number of dimensions possible. The appearancc of hypothetical solids from various perspectives is shown as well, for instance the four-dimcnsional and the seven-dimensional dices which are the multidimensional equivalents of a cubc
HIRSCHBERG’S ALGORITHM FOR APPROXIMATE MATCHING
Get PDFThe Hirschberg algorithm was devised to solve the longest common subsequence problem. The paper discusses the way o f adopting the algorithm to solve the string matching problem in linear space to determine edit distancefor two strings and their alignment
SECURITY PROBLEM OF COMMUNICATION IN CORBA SYSTEM
Get PDFCORBA standard defines the mechanisms o f shearing services. The key rule plays ORB (Object Reąuest Broker) which enables location o f suitable serwer and transparent com- munication between client and serwer. This paper presents problems connected with security during communication between ORB systems. In the CORBA system the objects are identified by IOR (Interoperable Object Reference). For TCP/IP it contains IP serwer address, port and object key. Filtration may use such information as: type o f communicate, IP address o f client, object key to which client wants to access, type o f operation, clients principal. In proposed implementation thefirewall works as CORBA serwer and cooperates with half- bridge. It is registered in ORB system and provides the controlling functions fo r entering packages by IDL interface. In the paper also the structure o ffiltering module is presented. Its main part is ACL (Access Control List) with rules o f access. The performance evaluation results are also presented