| 51. |
- Löfstrand, Magnus, et al.
(författare)
-
User-driven design of a flexible distance education environment : rationale, lessons learned and future implications
- 2008
-
Ingår i: Proceedings. - Piscataway, NJ : IEEE Communications Society. - 769531156 ; , s. 85-92, s. 85-92
-
Konferensbidrag (refereegranskat)abstract
- This paper discusses the challenges inherent in distributed education and presents the development of a distance education environment to meet the needs of educators and geographically dispersed students at Luleå University of Technology in northern Sweden. The design rationale and experiences from teaching in the environment are discussed. During the course of the research, several prerequisites for quality distance education were identified, one of which is the main topic of this paper. Here, the needs identified by the educators who are to se the created environment are discussed. Those needs have led to the design of the environment, including physical spaces, tools and technologies. Our results indicate that it is now possible to design a highly useful environment for distributed education at a much lower cost-to-quality ratio than only a few years ago. Such a system may be created in a way that allows teachers to earn to use the environment selfsufficiently. Thereby, the need for support staff is greatly diminished. The results indicate that the use of appropriate methods and tools lets teachers work in a distributed environment in a way that closely resembles their normal way of work in a teaching situation. In addition, a strategy for future development of the environment, based on the results presented here and on previous research, is suggested.
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| 52. |
- Paul, Satyam, et al.
(författare)
-
A Vibration Based Automatic Fault Detection Scheme for Drilling Process Using Type-2 Fuzzy Logic
- 2022
-
Ingår i: Algorithms. - : MDPI. - 1999-4893. ; 15:8
-
Tidskriftsartikel (refereegranskat)abstract
- The fault detection system using automated concepts is a crucial aspect of the industrial process. The automated system can contribute efficiently in minimizing equipment downtime therefore improving the production process cost. This paper highlights a novel model based fault detection (FD) approach combined with an interval type-2 (IT2) Takagi–Sugeno (T–S) fuzzy system for fault detection in the drilling process. The system uncertainty is considered prevailing during the process, and type-2 fuzzy methodology is utilized to deal with these uncertainties in an effective way. Two theorems are developed; Theorem 1, which proves the stability of the fuzzy modeling, and Theorem 2, which establishes the fault detector algorithm stability. A Lyapunov stabilty analysis is implemented for validating the stability criterion for Theorem 1 and Theorem 2. In order to validate the effective implementation of the complex theoretical approach, a numerical analysis is carried out at the end. The proposed methodology can be implemented in real time to detect faults in the drilling tool maintaining the stability of the proposed fault detection estimator. This is critical for increasing the productivity and quality of the machining process, and it also helps improve the surface finish of the work piece satisfying the customer needs and expectations.
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| 53. |
- Paul, Satyam, 1981-, et al.
(författare)
-
Discrete Time Sliding Mode Control of Milling Chatter
- 2020
-
Ingår i: ICCSAMA 2019. - Cham : Springer-Verlag New York. - 9783030383633 - 9783030383640 ; , s. 381-390
-
Bokkapitel (refereegranskat)abstract
- The technique of mitigating chatter phenomenon in an effective manner is an important issue from the viewpoint of superior quality machining process with quality production. In this paper, an innovative solution to control chatter vibration actively in the milling process is presented. The mathematical modelling associated with the milling technique is presented in the primary phase of the paper. In this paper, an innovative technique of discrete time sliding mode control(DSMC) is blended with Type 2 fuzzy logic system. Superior mitigation of chatter is the outcome of developed active controller. The Lyapunov scheme is implemented to validate the stability criteria of the proposed controller. The embedded nonlinearity in the cutting forces and damper friction are compensated in an effective manner by the utilization of Type-2 fuzzy technique. The vibration attenuation ability of DSMC-Type-2 fuzzy (DSMC-T2) is compared with the Discrete time PID (D-PID) and DSMC-Type-1 fuzzy (DSMC-T1) for validating the effectiveness of the controller. Finally, the numerical analysis is carried out to validate that DSMC-T2 is superior to D-PID and DSMC-T1 in the minimization of the milling chatter.
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| 54. |
- Paul, Satyam, 1981-, et al.
(författare)
-
Intelligent Fault Detection Scheme for Drilling Process
- 2019
-
Ingår i: ICCMA 2019. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781728137889 - 9781728137872 ; , s. 347-351
-
Konferensbidrag (refereegranskat)abstract
- Automatic fault detection system is an important aspect of industrial process and can contribute significantly for minimizing equipment downtime thus makingit a cost effective process. In this paper, an innovative model-based faultdetection (FD) system in combination with interval type-2 (IT2) Takagi-Sugeno(T-S) fuzzy system is developed for the detection of the faults in the drillbit of the drilling system. The proposed methodology validates the stabilityof the fault detection system in the presence of system uncertainties. Numerical analysis is carried out to prove the effectiveness of the theoretical approach. The effective methodology can be implemented in real time for detecting faults during downhole drilling operations.
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| 55. |
- Reed, Sean, et al.
(författare)
-
A modelling language for maintenance task scheduling
- 2012
-
Ingår i: 11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012. - New York : Curran Associates, Inc.. - 9781622764365 ; , s. 201-211
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a modelling language for representing the details necessary to analyse and model the implementation of maintenance strategies for generic hardware. The maintenance strategy determines which, and when, restorations and inspections should take place whilst the scheduling of maintenance tasks implements these goals. The manner of maintenance strategy implementation therefore has important implications for maintenance cost and other performance metrics. Despite this, maintenance strategy optimisation models found in the literature lack detailed maintenance implementation models, which may lead to inaccurate and misleading results. The presented modelling language permits the representation of all common constraints and outcomes between maintenance tasks that influence task schedules. In doing so, it provides a platform for the future development of maintenance task schedule modelling, planning and decision support tools. The modelling language is demonstrated through application to part of a car braking system
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| 56. |
- Reed, Sean, et al.
(författare)
-
A modelling language for maintenance task scheduling
- 2012
-
Ingår i: 11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012. - New York : Curran Associates, Inc.. - 9781622764365 ; , s. 201-211
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a modelling language for representing the details necessary to analyse and model the implementation of maintenance strategies for generic hardware. The maintenance strategy determines which, and when, restorations and inspections should take place whilst the scheduling of maintenance tasks implements these goals. The manner of maintenance strategy implementation therefore has important implications for maintenance cost and other performance metrics. Despite this, maintenance strategy optimisation models found in the literature lack detailed maintenance implementation models, which may lead to inaccurate and misleading results. The presented modelling language permits the representation of all common constraints and outcomes between maintenance tasks that influence task schedules. In doing so, it provides a platform for the future development of maintenance task schedule modelling, planning and decision support tools. The modelling language is demonstrated through application to part of a car braking system.
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| 57. |
- Reed, Sean, 1982-, et al.
(författare)
-
An efficient algorithm for computing exact system and survival signatures of K-terminal network reliability
- 2019
-
Ingår i: Reliability Engineering & System Safety. - : Elsevier. - 0951-8320 .- 1879-0836. ; 185, s. 429-439
-
Tidskriftsartikel (refereegranskat)abstract
- An efficient algorithm is presented for computing exact system and survival signatures of K-terminal reliability in undirected networks with unreliable edges. K-terminal reliability is defined as the probability that a subset K of the network nodes can communicate with each other. Signatures have several advantages over direct reliability calculation such as enabling certain stochastic comparisons of reliability between competing network topology designs, extremely fast repeat computation of network reliability for different edge reliabilities and computation of network reliability when failures of edges are exchangeable but not independent. Existing methods for computation of signatures for K-terminal network reliability require derivation of cut-sets or path-sets which is only feasible for small networks due to the computational expense. The new algorithm utilises binary decision diagrams, boundary set partition sets and simple array operations to efficiently compute signatures through a factorisation of the network edges. The performance and advantages of the algorithm are demonstrated through application to a set of benchmark networks and a sensor network from an underground mine.
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| 58. |
- Reed, Sean, 1982-, et al.
(författare)
-
Discrete Event Simulation Using Distributional Random Forests to Model Event Outcomes
- 2022
-
Konferensbidrag (refereegranskat)abstract
- In discrete event simulation (DES), the events are random (aleatory) and typically represented by a probability distribution that fits the real phenomena that is studied. The true distributions of event outcomes, which may be multivariate, are often dependent on the values of covariates and this relationship may be complex. Due to difficulties in representing the influence of covariates within DES models, often only the averaged distribution or expected value of the conditional distribution is used. However, this can reduce modelling accuracy and prevent the model from being used to study the influence of covariates. Distributional random forests (DRF) are a machine learning technique for predicting the multivariate conditional distribution of an outcome from the values of covariates using an ensemble of decision trees. In this paper, the benefits of utilizing DRF in DES are explored through comparison with alternative approaches in a model of a powder coating industrial process.
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| 59. |
|
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| 60. |
- Reed, Sean, et al.
(författare)
-
Estimating the availability of hydraulic drive systems operating under different functional profiles through simulation
- 2015
-
Ingår i: Safety and Reliability. - : Taylor & Francis Group. - 0961-7353 .- 2469-4126. ; 35:2, s. 4-19
-
Tidskriftsartikel (refereegranskat)abstract
- Hydraulic drive systems are widely used in a variety of industrial applications where high torque and low speed rotational power are required. The advantages include maximum torque from zero speed, continuously variable speed within wide limits, high reliability and insensitivity to shock loads. A drive system consists of a hydraulic circuit, electric motors, hydraulic pumps, hydraulic motors and auxiliary components. The stress on the components, and hence wear and failure rate, varies with the torque and speed output by the drive. The reliability of a hydraulic drive system of a particular design can therefore vary significantly between installations operating in applications with different functional requirements. Predicting the availability of a drive system in a particular application is useful for several purposes such as optimising the system design and estimating support costs. This paper describes a simulation model, developed to estimate the availability of a hydraulic drive system in a given functional profile, consisting of output torque and speed time phase requirements. It outputs statistics on system availability and component failure rates. As an example, the simulation model is used to compare these statistics for a drive design operating under two distinct operational profiles.
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| 61. |
|
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| 62. |
- Reed, Sean, et al.
(författare)
-
Logical Representation of Maintenance Procedures for Verification and Analysis
- 2016
-
Ingår i: 2016 11th IEEE System of Systems Engineering Conference (SoSE), IEEE. - : IEEE. - 9781467387279
-
Konferensbidrag (refereegranskat)abstract
- This paper describes a methodology using Petri nets, multi-valued logic and simulation to validate the correctness and measure the performance of maintenance procedure designs. A maintenance procedure design specifies a sequence of tasks for diagnosing faults, restoring availability or extending the time to failure for a particular hardware system. These procedures can be complex if they feature multiple possible task outcomes, concurrent task execution and application to multi-component multi-state hardware systems. The modelling language provides a means of testing the design of such procedures to ensure they are completely specified and optimised for efficient performance in terms of achieving desired outcomes, completion time, resource usage and safety.
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| 63. |
|
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| 64. |
- Reed, Sean, 1982-, et al.
(författare)
-
Modelling cycle for simulation digital twins
- 2021
-
Ingår i: Manufacturing Letters. - : Elsevier. - 2213-8463. ; 28, s. 54-58
-
Tidskriftsartikel (refereegranskat)abstract
- Digital twins (DT) form part of the Industry 4.0 revolution within manufacturing and related industries. A DT is a digital model (DM) of a real system that features continuous and automated synchronisation and feedback of optimisations between the real and digital domains. A core technology for predictive capabilities from DT is discrete event simulation (DES). The modelling cycle for developing and analysing DES models is significantly different compared to DM. A DT specific DES modelling cycle is introduced that is evolved from that of DM. The availability of specialised software tools for DT tailored to these differences would benefit industry.
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| 65. |
- Reed, Sean, 1982-, et al.
(författare)
-
Modelling stochastic behaviour in simulation digital twins through neural nets
- 2022
-
Ingår i: Journal of Simulation. - : Taylor & Francis. - 1747-7778 .- 1747-7786. ; 16:5, s. 512-525
-
Tidskriftsartikel (refereegranskat)abstract
- In discrete event simulation (DES) models, stochastic behaviour is modelled by sampling random variates from probability distributions to determine event outcomes. However, the distribution of outcomes for an event from a real system is often dynamic and dependent on the current system state. This paper proposes the use of artificial neural networks (ANN) in DES models to determine the current distribution of each event outcome, conditional on the current model state or input data, from which random variates can then be sampled. This enables more realistic and accurate modelling of stochastic behaviour. An application is in digital twin models that aim to closely mimic a real system by learning from its past behaviour and utilising current data to predict its future. The benefits of the approach introduced in this paper are demonstrated through a realistic DES model of load-haul-dump vehicle operations in a production area of a sublevel caving mine.
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| 66. |
- Reed, Sean, 1982-, et al.
(författare)
-
Service support system modelling language for simulation-driven development of functional products
- 2013
-
Ingår i: 2nd International Through-life Engineering Services Conference. - : Elsevier. ; 11, s. 420-424
-
Konferensbidrag (refereegranskat)abstract
- A functional product (FP) comprises of an integrated package of hardware and support services sold under a performance-based contract. A barrier to the adoption of FP is the lack of tools for obtaining predictions of availability and support costs during product development. A previous paper by the authors described a simulation-driven development strategy for designing FP that are optimised for functional availability and support costs. This iterative strategy involves representing the FP design in a modelling language; using a software code to automatically generate and analyse a simulation model from this representation to produce detailed performance predictions; and using these predictions as feedback to improve the design. The use of a modelling language facilitates the representation of the design details within the hardware and support system that influence availability and support costs. This includes the maintenance process design, maintenance strategy design and maintenance resource availability design. In this paper, an overview of a modelling language the authors have developed for this purpose is described.
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| 67. |
|
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| 68. |
- Törlind, Peter, et al.
(författare)
-
Towards true collaboration in global design teams?
- 2005
-
Ingår i: Proceedings ICED 05, the 15th International Conference on Engineering Design. - Barton : Institution of Engineers, Australia. - 0858257882
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Today’s collaboration tools can support formal meetings to a certain extent, though there is still an immense potential for improvement when it comes to designing virtual and physical places where global design teams can collaborate in more ‘natural’ ways than existing distributed environments allow. One challenge for global product development is to support true collaboration within global design teams, where diversity and competences of the whole team can be utilized and where team members can think together rather then merely exchange information, opinions and divide work. This paper summarizes the results of several case studies and development projects performed within the Polhem Laboratory over the last four years and proposes challenges for future research. From our findings some of the most important challenges are how to support users with communication tools for more natural formal and informal communication (i.e. as a co-located team communicates), while automatically storing information and context from the distributed meetings.
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