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The use of micro-simulation in determining the capacity of a roundabout with a multi-channel pedestrian flow
Tomaž Tollazzi, Tone Lerher, Matjaž Šraml, 2008, izvirni znanstveni članek

Opis: The main purpose of this paper is to analyse the influence of the multi-channel pedestrian flow on the capacity of the one-lane roundabout, using discrete simulation methods. The proposed model is based on the theory of the expected time void between the units of pedestrian traffic flow, which have the priority when crossing the arm of the roundabout. The proposed model represents an upgrade of the previous research in the field of modelling traffic flows in the one-lane roundabout. While the previous model of the pedestrian crossing is handled as the single-channel system in which the pedestrians arrive randomly from one side of the pedestrian crossing only, the proposed model deals with the multi-channel system in which the pedestrians arrive randomly from both sides of the pedestrian crossing. In thi sway the mathematical model can better illustrate the real conditions. The previous model considers only the disturbances of entry traffic flow of motorised vehicles caused by the pedestrian flow crossing the roundabout arm. The proposed model considers the disturbances caused by the circular traffic flow of motorised vehicles as well. A simulation analysis has been conducted on the roundabout at Koroška Street in Maribor, in which the counting of the motorised traffic flow and the pedestrian flow has been performed in the morning peek hour. The results of the analysis have indicated a high reserve of the capacity for pedestrians who arrive from the left and right sides of the roundabout with regard to motorised vehicles in the analysed arm of the roundabout. The real reserve of the capacity would otherwise be smaller in case of enlargement of the motorised vehicle flow in the future. Nevertheless it would be high enough for an undisturbed traffic flow of motorised vehicles through the roundabout to be possible. The presented methodology represents a practicable and adaptable tool for planning the roundabout capacity in practice and for the sensitivity analysis of individual variables on the throughput capacity of the roundabout.
Ključne besede: roundabout, pedestrian flow, traffic flow modeling, simulation models
Objavljeno: 31.05.2012; Ogledov: 1247; Prenosov: 26
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Model transformations require formal semantics
Yu Sun, Zekai Demirezen, Tomaž Lukman, Marjan Mernik, Jeffrey G. Gray, 2008, objavljeni znanstveni prispevek na konferenci

Opis: Despite the increasing interest in model-driven engineering, there are many open issues that need to be addressed to advance the technology and promote its adoption. This position paper outlines several current limitations of model transformation, with a specific emphasis on model optimization. A primary shortcoming that can be found in many model transformation approaches and tools is the lack of formal semantics to define the meaning of a modeling abstraction. This inadequacy is the source of many problems surrounding the practice of model engineering.
Ključne besede: domain-specific languages, program transformation, model transformation, model-driven engineering, modeling language
Objavljeno: 31.05.2012; Ogledov: 901; Prenosov: 22
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Is my DSL a modeling or programming language?
Yu Sun, Zekai Demirezen, Marjan Mernik, Jeffrey G. Gray, Barrett Richard Bryant, 2008, objavljeni znanstveni prispevek na konferenci

Opis: It is often difficult to discern the differences between programming and modeling languages. As an example, the term "domain-specific language" has been used almost interchangeably in academia and industry to represent both programming and modeling languages, which has caused subtle misconceptions. The borders between a modeling and programming language are somewhat vague and not defined crisply. This paper discusses the similarities and differences between modeling and programming languages, and offers some suggestions on how to better differentiate such languages. A list of criteria is presented for language classification, but it is suggested that a set of the criteria be used, rather than a single criterion. Several example domain-specific languages are used as case studies to motivate the discussion.
Ključne besede: domain-specific languages, programming languages, modeling language
Objavljeno: 31.05.2012; Ogledov: 784; Prenosov: 15
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A generalized neural network model of ball-end milling force system
Uroš Župerl, Franc Čuš, Bogomir Muršec, Anton Ploj, 2005, izvirni znanstveni članek

Opis: The focus of this paper is to develop a reliable method to predict 3D cutting forces during ball-end milling process. This paper uses the artificial neural networks (ANNs) approach to evolve an generalized model for prediction of cutting forces, based on a set of input cutting conditions. A set of ten input milling parameters that have a major impact on the cutting forces was chosen to represent the machining conditions. The training of the networks is performed with experimental machining data. This approach greatly reduces the time-consuming mathematical work normally required for obtaining the cutting force expressions. The estimation performance of the network is evaluated through a detailed simulation study. The accuracy of an analytical model, which is a feasible alternative to the network, is compared to that of the network. With similar system parameter estimates for both methods, the network is found to be considerably more accurate than the analytical model. The results of model validation experiments on machining Ck45 are also reported. Experimental results demonstrate that this method can accurately estimate feed cutting force within an error of 4%. The results also indicate that when the combination of sigmoidal and gaussian transfer function were applied, the prediction accuracy of neural network is as high as 98%.
Ključne besede: end-milling, cutting forces, cutting parameters, generalized neural networks, modeling
Objavljeno: 01.06.2012; Ogledov: 1365; Prenosov: 24
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Modeling and simulating the self-similar network traffic in simulation tool
Matjaž Fras, Jože Mohorko, Žarko Čučej, 2012, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Ključne besede: modeling, simulating, network traffic
Objavljeno: 01.06.2012; Ogledov: 709; Prenosov: 21
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Mathematical model of IRIS replication mechanism for the simulation of tactical networks
Jože Mohorko, Matjaž Fras, 2009, izvirni znanstveni članek

Opis: The Multilateral Interoperability Programme (MIP) was established to promote more successful and better harmonized operational functions for international peace-keeping forces. The C2IEDM/JC3IEDM (Command and Control Information Exchange Data Model) ensures the interconnection of Command and Control Information Systems (C2ISs) throughout all levels, from the corps down to the lower ranks. The usability of C2ISs highly correlates with the capacities of data information carriers, and the need is growing for greater capacity and reliability of transmission media and cryptographic message security. Simulation of tactical networks is an important task in planning military missions. Such methodologies assure a higher probability of success during critical tactical operations. This article focuses on a new radio network modeling method for the C2IS, which is verified by the OPNET simulation environment. This modeling method can be used in tactical radio network planning and optimization processes.
Ključne besede: communications, tactical networks, tactical radio networks, traffic modelling, radio network modeling, simulations, C2IS
Objavljeno: 01.06.2012; Ogledov: 1124; Prenosov: 25
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Modeling distributed real-time applications with specification PEARL
Roman Gumzej, Shourong Lu, 2007, izvirni znanstveni članek

Opis: The methodology of hardware/software co-design of embedded control systems with Specification PEARL is presented. Hardware and software are modeled with the language Specification PEARL, which has its origins in standard Multiprocessor PEARL. Its usefulness is enhanced for modeling hierarchical and asymmetrical multiprocessor systems, and by additional parameters for schedulability analysis. Graphical symbols are introduced for its constructs to enable graphical modeling while maintaining the semantical background. It is meant to be a superlayer for programs, based on the PEARL programming model. To model program tasks, Timed State Transition Diagrams have been defined. The model of a co-designed system is verified for feasibility with co-simulation. The resulting information should be used when considering changes in a current design with the goal of producing a temporally feasible model. To support dynamic re-configurations, configuration management is introduced into the models. Since UML is becoming a de facto standard also for designing embedded control systems, and since Timed State Transition Diagrams and State Chart Diagrams share great similarity, an interface of the methodology to UML 2 is defined, using UML's extension mechanisms.
Ključne besede: specification language, application modeling, co-design, co-simulation, configuration management, PEARL, UML
Objavljeno: 01.06.2012; Ogledov: 898; Prenosov: 31
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Critical plane modelling of fatigue initiation under rolling and sliding contact
Matjaž Šraml, Jože Flašker, Iztok Potrč, 2004, izvirni znanstveni članek

Opis: Contact fatigue is a phenomenon of important practical significance for engineering applications involving localized contacts, such as gears, rail wheel system and rolling bearings. The service lifetime of such components is related to damage, which results from the contact fatigue. The process in the material structure that causes this kind of failure is quite complicated. The aim of the present paper is to describe a contact fatigue initiation criterion, based on the critical plane approach for the general contact problem. On the basis of contact stress analysis with modified Hertzian boundary conditions, the loading cycle of characteristic material points in the contact area is determined. The Dang Van damage initiation criterion is based on the critical plane approach, which combines the largest allowable shearing and hydrostatic stresses (tensile and compressive), with an assumed elastic shakedown behaviour and it is used in this work. The material point of initial fatigue damage is then determined at the transition of the loading cycle stresses over the critical plane. The model assumed a homogeneous and elastic material model, without any imperfections or residual stresses, and elastic shakedown is considered. A proper determination of loading cycles and their characteristic values is of significance for contact fatigue initiation analysis. Finally, determination of the most critical material point on or under the contact surface and related number of loading cycles required for fatigue damage initiation is calculated with the strain-life (▫$epsilon$▫-N) method.
Ključne besede: machine elements, contact fatigue, crack initiation, strain life method, critical plane approach, numerical modeling
Objavljeno: 01.06.2012; Ogledov: 1076; Prenosov: 34
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Impact of stator pole shape of synchronous motor on torque
Anton Hamler, Mladen Trlep, Bojan Štumberger, Marko Jesenik, 2002, objavljeni znanstveni prispevek na konferenci

Opis: The paper presents pole modelling of small one phase 10 poles synchronous motor with permanent magnets. The purpose of stator pole modelling is to provide a reliable operation of the motor with in advance prescribed direction of rotation with 80 % of the rated voltage. For analysis of magnetic conditions the 2D finite element method was used. Intuitive and trial modelling procedures were used for pole modelling.
Ključne besede: synchronous motors, permanent magnets, magnetic analysis, finite element method, stator pole, stator pole modeling
Objavljeno: 01.06.2012; Ogledov: 1272; Prenosov: 23
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Modeling of forming efficiency using genetic programming
Miran Brezočnik, Jože Balič, Zlatko Kampuš, 2001, izvirni znanstveni članek

Opis: This paper proposes new approach for modeling of various processes in metal-forming industry. As an example, we demonstrate the use of genetic programming (GP) for modeling of forming efficiency. The forming efficiency is a basis for determination of yield stress which is the fundamental characteristic of metallic materials. Several different genetically evolved models for forming efficiency on the basis of experimental data for learning were discovered. The obtained models (equations) differ in size, shape, complexity and precision of solutions. In one run out of many runs of our GP system the well-known equation of Siebel was obtained. This fact leads us to opinion that GP is a very powerful evolutionary optimization method appropriate not only for modeling of forming efficiency but also for modeling of many other processes in metal-forming industry.
Ključne besede: metal forming, yield stress, forming efficiency, mathematical modeling, adaptation, genetic methods, genetic algorithm, genetic programming, artificial intelligence, process optimisation
Objavljeno: 01.06.2012; Ogledov: 934; Prenosov: 36
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