91. Specification PEARL constructs for embedded real-time systems co-designRoman Gumzej, Matjaž Colnarič, 2002, original scientific article Abstract: In the article a HW/SW co-design methodology is presented, which enables early reasoning about system integration as well as verification of the designs. Specification PEARL methodology is based on a specification language with the same name, whose ori-gins are in the standard Multiprocessor PEARL language. It has been enhanced by addi-tional components for asymmetrical multiprocessor systems design as well as by additional parameters for RTOS parameterisation and feasibility analysis. Timed State Transition Diagrams have been introduced for program/task modelling, supporting the PEARL pro-cess model. The resulting task models are easily translated to PEARL task prototypes. The methodology and its specification language components are being presented.
Keywords: embedded systems, real-time systems, co-design, modelling, PEARL
Published in DKUM: 01.06.2012; Views: 2614; Downloads: 25
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92. Workloads and standard time norms in garment engineeringZvonko Dragičević, Daniela Zavec Pavlinič, Jelka Geršak, 2002, original scientific article Abstract: Posibilities of new methods for measuring loading and standard time norms are presented, as applied in the field of garment engineering. Measurements deescribed are performed on modern measuring equipment designed to measure and perform computer analysis of temporal values of processing parameters in sewing operation and simultaneously record in two planes using a video system. The measuring system described was used to investigate sewing operation for the seam on a ladies' fashion suit, 52 cm long. For the operation investigated, method of work employing the MTM (Methods Time Measurements) system with analysis of basic movements was selected. The MTM system used shows that normal time for the operation in question is around 429.3 TMU (15.5 s). Investigations of workload imposed on the worker according to the OADM method were done simultaneously, and total ergonomic loading coefficients of Ker=0.082 was established, thus determining the time necessary to organise the process of work as 464.5 TMU (16.7 s). Simultaneous measurements of time and dynamic changes of processing parameters, as well as logical sets of movements, are important for defining favourable operation structures, time norms ergonomically designed systems of work and workplaces in garment engineering, as early as in the phase of designing operation. The investigations described make possible to find optimal distribution of working elements and zones of reach important for ergonomic designing and/or re-designing of workplaces, which results in considerably reduced level of fatigue in work optimal quality level, higher degree of utilisation of equipment installed and lower manufacturing costs.
Keywords: garment engineering, sewing, standard time norms, norms, time study, work study, MTM, motion timestudy measurement
Published in DKUM: 01.06.2012; Views: 2050; Downloads: 57
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93. Extended Lindstedt-Poincare method for non-stationary resonances of dynamical systems with cubic nonlinearitRudi Pušenjak, 2008, original scientific article Abstract: This paper presents the extended Lindstedt-Poincare (EL-P) method, which applies multiple time variables to treat non-stationary oscillations arising in dynamical systems with cubic nonlinearities due to the slowly varied excitation parameters. The method is applied extensively in research of non-stationary vibrations of clamped-hinged beams. Recognizing the aperiodic nature of non-stationary oscillations, the new formulation is presented by adding an additional, slow time scale beside time scales of the nonlinear system, which generally correspond to the incommensurate nonlinear frequencies of the response. Using this concept, a generalized approach of the study to the passage through fundamental, superharmonic and subharmonic resonances is presented in the paper. Effects of slowly varying excitation frequency and slowly varying excitation amplitude on the non-stationary oscillations are studied with the computation of deviations from the stationary response. Although the method is formulated for N-dof dynamical systems having weak cubic nonlinearities, it is applied for non-stationary vibrations, where two-mode shape approximation of damped and undamped clamped-hinged beam, respectively, is used and the simultaneous appearance of internal resonance is taken into account. Stability analysis of stationary solutions is performed and comparisons of stationary resonance curves by results obtained with the incremental harmonic balance (IHB) method show good agreement. The passage through the fundamental resonance of damped and undamped clamped-hinged beam, respectively, is investigated in detail.
Keywords: dynamical systems with cubic nonlinearities, nonlinear oscillations, nonstationary nonlinear oscillations, time scales, excitation frequency, resonance, Lindstedt-Poincare method
Published in DKUM: 01.06.2012; Views: 2114; Downloads: 36
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94. Analytical travel time models for multi aisle automated storage and retrieval systemsTone Lerher, Matjaž Šraml, Janez Kramberger, Iztok Potrč, Matej Borovinšek, Blaž Zmazek, 2005, original scientific article Abstract: Multi aisle automated storage and retrieval systems correspond to multiple picking aisles served by a single storage and retrieval machine. These systemsare used in practice when the need for pallet places is high and the throughput capacity is relatively low. Therefore, considerable savings of initial investment costs due to single aisle systems can be achieved using such systems. The objective of the presented study is to develop analytical travel time models for multi aisle automated storage and retrieval systems considering the operating characteristics of the storage and retrieval machine. With the proposed analytical travel time models, average travel time of the storage and retrieval machine, from which the performance of multi aisle automated storage and retrieval systems can be evaluated is determined. A simulation model of multi aisle automated storage and retrieval systems was developed to compare the performances of the proposed analytical travel time models. An example of multi aisle automated storage and retrieval systems withfive picking aisles was presented for the evaluation purpose. The results show that proposed analytical travel time models perform satisfactory according to the results of simulation analysis and could be very useful toolsfor designing of multi aisle automated storage and retrieval systems in real-world applications.
Keywords: warehousing, logistics, high rack storage, simulations, travel time models
Published in DKUM: 01.06.2012; Views: 2425; Downloads: 95
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95. Chemical composition of Juniperus communis L. fruits supercritical CO2 extracts: dependence on pressure and extraction timeBranislava Barjaktarović, Milan Sovilj, Željko Knez, 2005, original scientific article Abstract: Ground fruits of the common juniper (Juniperus communis L), with a particle size range from 0.2500.400 mm, forming a bed of around 20.00 +/- 0.05 g, were extracted with supercritical CO2 at pressures of 80,90, and 100 bars and at a temperature of 40 De. The total amount of extractable substances or global yield (mass of extract/mass of raw material) for the supercritical fluid extraction process varled from 0.65 to 4.00"10 (wt). At each Investigated pressure, supercriticaI CO2 extract fractions collected In successive time intervals over the course of the extraction were analyzed by capillary gas chromatography, using flame ionization (GO-FIO) and mass spectrometric detection (GC-MS). More than 200 constituents were detected In the extracts, and the contents of 50 compounds were reported in the work. Dependence of the percentage yields of monoterpene, sesquiterpene, oxygenated monoterpene, and oxygenated sesquiterpene hydrocarbon groups on the extraction time was investigated, and conditions that favored the yielding of each terpene groups were emphasized. At all pressures, monoterpene hydrocarbons were almost completely extracted from the berries in the first 0.6 h. It was possible to extract oxygenated monoterpenes at 100 bar in 0.5 h and at 90 bar in 1.2 h. Contrary to that, during an extraction period of 4 h at 80 bar, it was possible to extract only 75% of the maximum yielded value of oxygenated monoterpene at 100 bar. Intensive extraction of sesquiterpenes could be by no means avoided at any pressure, but at the beginning of the process (the first 0.5 h) at 80 bar, they were extracted about a and 3 times slower than at 100 and 90 bar, respectively. Oxygenated sesquiterpenes were yielded at fast, constant extraction rates at 100 and 90 bar In 1.2 and 3 h, respectively. This initial fast extraction period was consequently foIlowed by much slower extraction of oxygenated sesquiterpenes.
Keywords: chemical processing, high pressure technology, CO2, supercritical fluid extraction, pressure, extraction time, Juniperus communis, oxygenated terpenes, juniper berry oil, carbon dioxide
Published in DKUM: 01.06.2012; Views: 2229; Downloads: 57
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96. A safety shell for UML-RT projectsRoman Gumzej, Wolfgang A. Halang, 2008, published scientific conference contribution Abstract: A safety shell pattern was defined based on a reconfiguration management pattern, and inspired by the architectural specifications in Specification PEARL. It is meant to be used for real-time applications to be developed with UML-RT as described. The implementation of the safety shell features as defined by in [8], namely its timing and state guards as well as I/O protection and exception handling mechanisms, is explained. The pattern is parameterised by defining the properties of its components as well as by defining the mapping between software and hardware architectures. Initial and alternative execution scenarios as well as the method for switching between them are defined. The goal pursued with the safety shell is to obtain clearly specified operation scenarios with well defined transitions between them. To achieve safe and timely operation, the pattern must provide safety shell mechanisms for an application designed, i.e., enable its predictable deterministic and temporally predictable operation now and in the future.
Keywords: real-time systems, embedded systems, UML profiles, UML patterns, safety
Published in DKUM: 31.05.2012; Views: 1770; Downloads: 172
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97. Discussion on: "Analysis of control relevant coupled nonlinear oscillatory systems"Rudi Pušenjak, Maks Oblak, 2008, original scientific article Abstract: The paper by I. D. Landau et al. presents an analysis of two structures of coupled van der Pol oscillators done by using the Krylov-Bogoliubov (K-B) averaging method. They devise the K-B method to effectively compute self-excited and externally driven oscillations, respectively on systems presumably subjected to control, where amplitudes and phases are slowly varying functions of time. After they present feedback structures of single and coupled generalized van der Pol equations, respectively, they perform the K-B analysis of these equations, which results in explanation of various regimes of self-excited and externally driven oscillations including the analysis of the combustion instability model. Although the proposed K-B methodmay be considered as a step forward in modeling self-oscillating systems, this discussion wants to show, that problems solved by the K-B method can be treated also in an alternative way. Based on the paper [1], it is obvious that coupled van der Pol oscillators, driven by an external excitation with slowly varying frequency or amplitude, can be analyzed by using Extended Lindstedt- Poincare (EL-P) method with multiple time scales.
Keywords: van der Pol oscillators, external excitation, multiple time scales
Published in DKUM: 31.05.2012; Views: 1623; Downloads: 69
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98. A novel approach for assuring and following inoculum activity during kefir grains growth studies : application of dynamic pH profilesMarko Tramšek, Andreja Goršek, 2007, original scientific article Abstract: The profiles of kefir grains growth curves strongly depend on bioprocess conditions and inoculum viability. Therefore, accurate growth curve studies require the use of optimally active kefir grains as inoculum. Accordingly, the main objective of our study was experimental optimization of classic kefir grains activation procedure and afterwards, comparison among growth curves of differently activated kefir grains. For this purpose some experiments were initially performed in computer-controlled RC1 reactor provided data of dynamic pH profiles during batch propagation of differently activated grains. Experimental data were mathematically analyzed and using the special methodology of minimizing the absolute deviation of pH(t) profiles the minimal time for grains activation was determined. We established that optimal inoculum activity could be ensured only by the kefir grains, which were previously activated at least over eleven successive days. In the second part of research the growth curve of optimally activated kefir grains was constructed using experimental measurements and fitted with Gompertz model. The present results were compared with the results obtained by our previous study, where classically activated grains were used. We established that, inspite of equal daily kefir grain mass increase, considerable difference in growth curves of differently activated kefir grains exist.
Keywords: chemical processing, kefir grains, growth curve, minimal activation time, dynamic pH profiles, Gompertz model
Published in DKUM: 31.05.2012; Views: 2134; Downloads: 119
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99. Some aspects of fabric drapeDarja Žunič-Lojen, Simona Jevšnik, 2007, original scientific article Abstract: Drape is one of the important factors influencing the aesthetics and functionality of fabrics. Therefore, investigation into drape parameters is important for analysing its behaviour. Drape parameters were investigated from different aspects using the Cusick Drape meter and Image Analyser. Firstly, the influence of time on the drape coefficient and number of folds was studied over 24 hours. Usually, drape is considered as a static, time-independent problem. However, this investigation shows that the drape coefficient of a fabric changes si-gnificantly over a longer time period. Furthermore, the comparison of drape parameters is shown using samples with two different diameters. The larger samples have smaller drape coefficient than those with smaller diameters, and their drape is less changeable over time. Basically, the three-dimensional fabric drape is not an independent fabric property, there-fore, the connection between bending rigidity and drapecoefficient was studied. The last aspect of this investigation was the repeatability of drape measurements, and the establish-ment of the required number of measurements for drape coefficient and fold numbers.
Keywords: fabric drape, drape parameters, time-dependence, bending rigidity, measurement repeatibility
Published in DKUM: 31.05.2012; Views: 1892; Downloads: 57
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100. A reconfiguration pattern for distributed embedded systemsRoman Gumzej, Matjaž Colnarič, Wolfgang A. Halang, 2007, original scientific article Abstract: A reconfiguration pattern for UML-based projects of embedded (real-time) systems is defined. It enables to set up hardware/software configurations, and to specify conditions and methods for dynamic reconfiguration. The reconfiguration pattern was inspired by the reconfiguration management solution of the Specification PEARL methodology, which is based on the standard for Multiprocessor PEARL whose original idea it was to extend the language to enable the programming of distributed real-time applications in PEARL. In Specification PEARL, the possibility for abstract descriptions of hardware and software architectures and for defining mappings from software to hardware components has been enhanced in correspondence with the standard. Here, a UML pattern for reconfiguration management in distributed embedded applications based on concepts from Specification PEARL is presented. Its behavioural, structural and functional aspects are outlined. It addresses stereotype entities from the Specification PEARL language, which were joined in a UML profile, and outlines the related reconfiguration management mechanisms, which were carried over to the mentioned UML pattern. The proposed reconfiguration pattern is to facilitate the development of distributed embedded application in UML with consistent and temporally predictable reconfiguration support. It should also support and enhance the applicationsć flexibility and portability.
Keywords: real-time, distributed, embedded systems, dynamic reconfiguration, UML profiles and patterns, UML-RT, specification PEARL
Published in DKUM: 31.05.2012; Views: 2018; Downloads: 108
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