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2002

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Articles 1321 - 1350 of 1792

Full-Text Articles in Engineering

A Window-Based Software For Fatigue Crack Growth Data Reduction, B. Keeton, Tarun Goswami Jan 2002

A Window-Based Software For Fatigue Crack Growth Data Reduction, B. Keeton, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

The objective of this research is to develop a Windows-based program to present the fatigue crack growth rate and mode I stress intensity factor range data. Microsoft Visual Basic was used to write the code. The program developed in this study calls out the input data in terms of crack length (α) and the number of cycles (Ν). Secant and seven point polynomial distribution was used to fit the data. The installation procedure for the program was copied onto a disk to install the program. Future work is needed to further modify the a-N data and therefore to present da/dN-ΔΚ …

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Dwell Sensitivity Behavior And Modeling, E. Pyburn, Tarun Goswami Jan 2002

Dwell Sensitivity Behavior And Modeling, E. Pyburn, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Since engineering materials are exposed to dwell-times in service, it is important to understand the effects of dwell times on the fatigue life. The mechanisms controlling deformation and failure under dwell conditions are in terms of metallographic damage namely; transgranular fracture, intergranular fracture, mixed intergranular transgranular fracture modes, surface striated damage, creep damage and oxidation. These mechanisms are very difficult to include in a quantitative model to predict the dwell sensitivity behavior of high temperature materials. Published creep-fatigue data were compiled from various sources for a number of materials such as copper alloys (NARloy-Z, AMZ1RC), steel alloys (9Cr-lMo), and nickel …

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Statistical Modeling Of Fatigue Crack Growth, Ignacio Guerra, Tarun Goswami Jan 2002

Statistical Modeling Of Fatigue Crack Growth, Ignacio Guerra, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

The objective of this research is to fit normal and lognormal distributions to fatigue crack growth rate (da/dN) data and present the data in terms of cumulative frequency distribution (f (x)) and a variant of da/dN and mode I stress intensity factor range (ΔΚ), z. The probability density functions (F(da/dN)) were also plotted for the data. The data was compiled from open literature, conducted on a hot section turbine disk material Inconel 718 under a North Atlantic Treaty Organization (NATO) project, through the Advisory Group on Aerospace Research and Development (AGARD). Incomel 718 was tested at 650°C utilizing various specimen …

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Life Prediction Of Stainless Steels Used In Nuclear Reactors, Jonathan Clark, Tarun Goswami Jan 2002

Life Prediction Of Stainless Steels Used In Nuclear Reactors, Jonathan Clark, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Effects of dwell times and temperature on creep-fatigue behavior of stainless steels have been examined from published data. The temperatures of these materials varied from 430°C to 816°C. Within this temperature range creep and fatigue processes interact and failure occurs in the low-cycle regime. A least square best fit equation was developed from the compiled data fitting all the data points. The variables were temperature, strain rate, dwell time and strain range and were used with and without transformation functions to derive the equation. Statistical analysis was performed showing a very high coefficient of correlation value for the life prediction …

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Failure Modes Of Biomedical Implants, Andrew Gratton, Bert Buford, Tarun Goswami, Dana Gaddykurten, Larry Suva Jan 2002

Failure Modes Of Biomedical Implants, Andrew Gratton, Bert Buford, Tarun Goswami, Dana Gaddykurten, Larry Suva

Biomedical, Industrial & Human Factors Engineering Faculty Publications

The metallic biomaterials are very well known among various biomaterials. Stainless steel was used successfully as an implant material in the surgical field, then Vitallium, cobalt based alloys were used as implant materials. Titanium is the newest metallic biomaterial among three main metallic biomaterials, stainless steels, Co-based alloys and titanium alloys. These materials are used for the instrumentation replacing failed hard tissue, for example, artificial hip joints, artificial knee joints, bone plates, dental implants and in similar applications. Biocompatibility characteristics of titanium alloys make it the preferred choice for such applications, additional factors being light weight, excellent mechanical properties, corrosion …

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A Review Of Systems: New Paradigms For The Human Sciences, Martin Zwick Jan 2002

A Review Of Systems: New Paradigms For The Human Sciences, Martin Zwick

Complex Systems Faculty Publications and Presentations

This essay is a selective review of Systems: New Paradigms for the Human Sciences, edited by Gabriel Altmann and Walter A. Koch (Berlin: Walter de Gryter, 1998). It is selective because it is impossible to engage such a varied collection of systems-theoretic essays in a review of reasonable length. To invoke a relevant dialectical idea: the characteristic strength of any system is often also its characteristic weakness. One strength and weakness of the systems field is its great diversity, and this diversity is reflected in this volume by the range of subjects addressed in its 27 articles. I will not …

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Sar Simulations In Wireless Communication And Safety Discussions In The Society, M. O. Özyalçin, Funda Akleman, Levent Sevgi̇ Jan 2002

Sar Simulations In Wireless Communication And Safety Discussions In The Society, M. O. Özyalçin, Funda Akleman, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

Numerical simulation in cellular phone - human tissue interaction is discussed in this paper. The powerful time domain (TD) techniques, the transmission line matrix (TLM) and the finite-difference time-domain (FDTD) methods, are used to model mutual effects. The purpose is to calculate specific absorption rate (SAR; defined as the power absorbed by the unit mass of the tissue), validate the codes and verify the results. Also, effectiveness of the SAR parameter in determination of the exposure limits for human health and environmental pollution is discussed.

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Diabetic Patients Foot Care Using Smart Materials To Prevent Ulcerations/Amputations, Carrie Hahn, Ajay Mahajan, Marco P. Schoen Jan 2002

Diabetic Patients Foot Care Using Smart Materials To Prevent Ulcerations/Amputations, Carrie Hahn, Ajay Mahajan, Marco P. Schoen

Mechanical Engineering Faculty Research

A major cause of illness and disability in diabetic patients is complications affecting the lower limbs, particularly the feet where loss of feeling may result in ulcerations, and ultimately to partial or total amputation. Traditional remedies for this problem still remains in measuring the foot pressures and then designing a passive shoe insert that absorbs the high pressures. This process may then be repeated multiple times during the lifetime of the patient. This paper describes the conceptual design of an automatic system that monitors and controls the pressure levels in diabetic patients’ feet in real time. The scheme is based …

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Real-Time Measurement Of Surface Deformation Of Rotating Blades, Jay Maudlin, Ajay Mohan Mahajan, Tsuchin P. Chu Jan 2002

Real-Time Measurement Of Surface Deformation Of Rotating Blades, Jay Maudlin, Ajay Mohan Mahajan, Tsuchin P. Chu

Mechanical Engineering Faculty Research

This paper presents the results for the real-time measurement of surface deformation of rotating elements. A digital image correlation technique is used to estimate the surface displacements and strains. Speckle patterns are spray painted on the surface of interest and digital images taken before and during deformation caused by rotary motion. The digital image of the deformed blade is taken by freezing the speckled pattern with the help of a stroboscope. The technique provides several advantages over traditional methods in terms of obtaining whole-field deformation profiles, a non-invasive measurement scheme, and a simple and economical set-up. Results are presented for …

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Analysis Of Short Crack Growth In Particulate Composites, Ying Zhang, Tsuchin P. Chu, Ajay Mohan Mahajan, Chi Tsieh Liu Jan 2002

Analysis Of Short Crack Growth In Particulate Composites, Ying Zhang, Tsuchin P. Chu, Ajay Mohan Mahajan, Chi Tsieh Liu

Mechanical Engineering Faculty Research

This paper presents the analysis of the short-crack propagation and growth in particulate composite materials by using the image correlation techniques and fracture mechanics theory. The fracture mechanics model for a long crack does not work very well with short-crack propagation when the initial crack length is less than 5.1 mm (0.2 inch). In order to investigate the short crack effect, a series of tests of particulate composite specimens with long and short cracks have been performed and the results were recorded on a video tape. These test data were analyzed to determine the strain fields near the crack tip, …

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Effect Of Lcp Addition On The Properties Of Hybrid Composites, Sreekumar Pisharath, Shing Chung Josh Wong Jan 2002

Effect Of Lcp Addition On The Properties Of Hybrid Composites, Sreekumar Pisharath, Shing Chung Josh Wong

Mechanical Engineering Faculty Research

A hybrid composite consisting of rubber toughened nylon 6,6, glass fiber and LCP was investigated by varying LCP content. The hybrid system exhibited better processability than the glass fiber reinforced composite. A decrease in the total torque was observed with the LCP content indicating the reduction in the energy consumed during the processing of the hybrid composites. Thermal stability of the glass fiber reinforced composites improved with LCP addition. SEM observation of the tensile fracture surface revealed LCP fibrillation in the toughened matrix.

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Biological Fixed Film Systems, Mark W. Fitch, Ellen England Jan 2002

Biological Fixed Film Systems, Mark W. Fitch, Ellen England

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

No abstract provided.

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Behavior Of Screw Connections In Residential Construction, Roger A. Laboube, M. A. Sokol Jan 2002

Behavior Of Screw Connections In Residential Construction, Roger A. Laboube, M. A. Sokol

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Self-drilling screws are the primary means of fastening cold-formed steel members in residential construction. Because the fabrication of connections is the most labor-intensive aspect of the construction process, a better understanding of the behavior of screw connections could lead to more optimum connection design. Therefore, studies have been performed at the University of Missouri-Rolla aimed at developing a better understanding of the behavior of single-shear connections using self-drilling screws in cold-formed steel construction. The study's focus was on design parameters typically employed in residential construction. Fastener patterns, screw spacing, stripped screws, and the number of screws in a connection was …

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Preface, Alexander Kurz Jan 2002

Preface, Alexander Kurz

Engineering Faculty Articles and Research

No abstract provided.

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Definability, Canonical Models, And Compactness For Finitary Coalgebraic Modal Logic, Alexander Kurz, Dirk Pattinson Jan 2002

Definability, Canonical Models, And Compactness For Finitary Coalgebraic Modal Logic, Alexander Kurz, Dirk Pattinson

Engineering Faculty Articles and Research

This paper studies coalgebras from the perspective of the finitary observations that can be made of their behaviours. Based on the terminal sequence, notions of finitary behaviours and finitary predicates are introduced. A category Behω(T) of coalgebras with morphisms preserving finitary behaviours is defined. We then investigate definability and compactness for finitary coalgebraic modal logic, show that the final object in Behω(T) generalises the notion of a canonical model in modal logic, and study the topology induced on a coalgebra by the finitary part of the terminal sequence.

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Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor Jan 2002

Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor

Conference papers

A non-linear predictive controller is presented. It judiciously combines predictive controllers with a local model network utilizing a neural-network-like gating system. It avoids the time consuming quadratic optimization calculation, which is normally necessary in non-linear predictive control. A controller simulation on a Continuous Stirred Tank Reactor (CSTR) case study was shown to be satisfactory both in terms of set point tracking and regulation performance over the entire operating range. Moreover, the inherent integration action in the local predictive controller provides zero static offsets.

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Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer Jan 2002

Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer

Conference papers

This paper discusses the estimation of the parameters of a first order plus dead-time process model using the closed-loop step response data of the process under proportional plus integral (PI) control. The proportional gain and the integral time, in the PI controller, are chosen such that the closed-loop step response exhibits an under-damped response. From this response data, five characteristic points are used to determine a second order plus dead-time model and subsequently, the frequency response of the closed-loop system. Knowing the dynamics of the closed-loop system and the dynamics of the controller, the open-loop dynamics of the process can …

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Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer Jan 2002

Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer

Conference papers

This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification.

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Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis Jan 2002

Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis

Chemical & Biomedical Engineering Faculty Publications

Magnetic resonance (MR) phase-velocity mapping (PVM) is routinely being used clinically to measure blood flow velocity. Conventional nonsegmented PVM is accurate but relatively slow (3–5 min per measurement). Ultrafast k-space segmented PVM offers much shorter acquisitions (on the order of seconds instead of minutes). The aim of this study was to evaluate the accuracy of segmented PVM in quantifying flow from through-plane velocity measurements. Experiments were performed using four straight tubes (inner diameter of 5.6–26.2 mm), under a variety of steady (1.7–200 ml/s) and pulsatile (6–90 ml/cycle) flow conditions. Two different segmented PVM schemes were …

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Heat Transfer In A Thin Liquid Film In The Presence Of Electric Field For Non-Isothermal Interfacial Condition, Rama S.R. Gorla, Jorge E. Gatica, Bahman Ghorashi, Pijarn In-Eure, Larry W. Byrd Jan 2002

Heat Transfer In A Thin Liquid Film In The Presence Of Electric Field For Non-Isothermal Interfacial Condition, Rama S.R. Gorla, Jorge E. Gatica, Bahman Ghorashi, Pijarn In-Eure, Larry W. Byrd

Chemical & Biomedical Engineering Faculty Publications

Heat transfer enhancement in an evaporating thin liquid film using the electric field under non-isothermal interfacial condition is presented. A new mathematical model subjected to van der Waals attractive forces, the capillary pressure and the electric field is developed to describe the heat transfer enhancement in the evaporating thin liquid film. The effect of an electrostatic field on the curvature of the thin film, evaporative flux, pressure gradient distribution, heat flux, and heat transfer coefficient in the thin film is presented. The results show that the electric field can enhance heat transfer in the thin liquid film significantly. In addition, …

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Annular Planar Monopole Antennas, Z. N. Chen, Max Ammann, W.Y. W. Chia, T.S. P. See Jan 2002

Annular Planar Monopole Antennas, Z. N. Chen, Max Ammann, W.Y. W. Chia, T.S. P. See

Conference papers

A type of annular planar monopole antenna is presented. The impedance and radiation characteristics of the monopole with different holes and feed gaps are experimentally examined. The measured results demonstrate that the proposed antenna is capable of providing significantly broad impedance bandwidth with acceptable radiation performance.

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Precise Chemical Analysis Development For Si And Gaas Surfaces, T. A. Briantseva, Z. M. Lebedeva, D. V. Lioubtchenko, M. Nolan, T. S. Perova, R. A. Moore, Kevin Berwick Jan 2002

Precise Chemical Analysis Development For Si And Gaas Surfaces, T. A. Briantseva, Z. M. Lebedeva, D. V. Lioubtchenko, M. Nolan, T. S. Perova, R. A. Moore, Kevin Berwick

Articles

Precise chemical analysis (PCA) was developed to allow the study of non-interconnected atoms on crystalline semiconductor surfaces, such as those produced during rapid thermal processing (RTP) of silicon and electron beam lithography on gallium arsenide (GaAs). The PCA method is based on selectively dissolving the different components present on the semiconductor surface using preferential etchant solutions. After etching, the etchant solution, containing the etched component, is analyzed by a photometric technique. In this paper, we present photometric measurements of the amount of “free” (non-interconnected) atoms that remain on semiconductor surfaces following electron beam and RTP processing. In this context, “free” …

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An Efficient Procedure For Viscous Propeller Flow Field Calculations, Fergal Boyle Jan 2002

An Efficient Procedure For Viscous Propeller Flow Field Calculations, Fergal Boyle

Conference Papers

An efficient procedure has been developed for the computation of the three-dimensional, compressible, viscous flow field around a general propeller geometry with the inflow at zero angles of incidence and yaw. The solution procedure combines a recently developed Reynolds-Averaged-Navier-Stokes equations solver with a commercially available grid generator designed specifically for turbomachinery configurations. Preliminary results from the calculation of laminar and turbulent incompressible flow over a flat plate demonstrate that the flow solver is capable of capturing boundary-layer behaviour accurately. Results from the prediction of the transonic flow over a two-bladed propeller geometry show that the procedure is accurate and efficient …

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Safety Behaviour In The Construction Industry, Nick Macdonald, Victor Hrymak Jan 2002

Safety Behaviour In The Construction Industry, Nick Macdonald, Victor Hrymak

Reports

The influences on safety standards and employee safety behaviour was analysed on 18 large construction sites on the island of Ireland. The safety management and documentation of these sites was also analysed. The results are discussed at length together with comprehensive recommendations for the industry.

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Initial Experiences Gained And Initiatives Employed In The Teaching Of Java Programming In The Institute Of Technology Tallaght, Eamonn Hyland, Gary Clynch Jan 2002

Initial Experiences Gained And Initiatives Employed In The Teaching Of Java Programming In The Institute Of Technology Tallaght, Eamonn Hyland, Gary Clynch

Conference Papers

This paper describes recent experiences gained and initiatives employed in the teaching of Java programming to first and second year students in the Institute of Technology Tallaght from September 2000 to March 2002. It outlines some elearning, technological and pedagogical initiatives that were undertaken within the department and the resultant preliminary outcomes. The outcomes have been determined after detailed analysis of the results of a survey which was commissioned to determine the effectiveness of the initiatives and also to identify those parts of the Java language which were causing students particular difficulty. The students surveyed are currently completing their fourth …

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Calculation For The Parameter "Deflection" In A New Theory Of The Earth's Magnetic Field, Annraoi De Paor, Ted Burke Jan 2002

Calculation For The Parameter "Deflection" In A New Theory Of The Earth's Magnetic Field, Annraoi De Paor, Ted Burke

Articles

In a recent paper on the theory of the Earth’s magnetic field and key features of Sunspot activity (de Paor, 2001), a central role in the calculation of secular variations of the geomagnetic field was played by a newly-introduced parameter called the deflection (abbreviated def ). In this note, the significance of def is elucidated and the method used to calculate it is explained

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Ancient Astronomical Alignments: Fact Or Fiction?, Frank Prendergast Jan 2002

Ancient Astronomical Alignments: Fact Or Fiction?, Frank Prendergast

Articles

No abstract provided.

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Sub-Band Independent Subspace Analysis For Drum Transcription, Derry Fitzgerald, Robert Lawlor, Eugene Coyle Jan 2002

Sub-Band Independent Subspace Analysis For Drum Transcription, Derry Fitzgerald, Robert Lawlor, Eugene Coyle

Conference papers

While Independent Subspace Analysis provides a means of separating sound sources from a single channel signal, making it an effective tool for drum transcription, it does have a number of problems. Not least of these is that the amount of information required to allow separation of sound sources varies from signal to signal. To overcome this indeterminacy and improve the robustness of transcription an extension of Independent Subspace Analysis to include sub-band processing is proposed. The use of this approach is demonstrated by its application in a simple drum transcription algorithm.

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Walkthrough In Complex Environments At Interactive Rates Using Level-Of-Detail, Alper Selçuk, Uğur Güdükbay, Bülent Özgüç Jan 2002

Walkthrough In Complex Environments At Interactive Rates Using Level-Of-Detail, Alper Selçuk, Uğur Güdükbay, Bülent Özgüç

Turkish Journal of Electrical Engineering and Computer Sciences

One of the biggest problems in computer graphics is displaying huge geometric models at interactive rates. A lot of work has been done to achieve the required frame-rates in architecture, simulation, computer-aided design and entertainment applications. In this paper, a system that enables walkthrough in complex environments using level-of-detail approximations is explained. The system uses hierarchical triangulated models as input. In the preprocessing phase, multiresolution models of objects are created using polygonal simplification techniques. During walkthrough, fast frustum culling based on bounding boxes is performed to eliminate branches of hierarchy that are not visible. An appropriate level for detail of …

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A New Petri-Net-Based Synthesis Technique For Supervisory Control Of Discrete Event Systems, Murat Uzam, Anthony H. Jones Jan 2002

A New Petri-Net-Based Synthesis Technique For Supervisory Control Of Discrete Event Systems, Murat Uzam, Anthony H. Jones

Turkish Journal of Electrical Engineering and Computer Sciences

A new Petri-net-based top-down synthesis technique for supervisory control of Discrete Event Systems (DES) is proposed to solve the forbidden state problem. The supervisors obtained are compiled supervisors, whose control policy is represented as a net structure, as opposed to mapping supervisors, whose control policy is computed as a feedback function of the marking of the system. The compiled supervisors obtained by using the technique proposed in this paper are both nonblocking and maximally permissive. The supervisors to be synthesised consist of a controlled Automation Petri Net model of the system. Automation Petri Nets (APN) include the following extensions to …

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