| 1. |
- Catelani, Marcantonio, et al.
(författare)
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A Practical Solution for HVAC Life Estimation Using Failure Models
- 2020
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Ingår i: 17th IMEKO TC 10 and EUROLAB Virtual Conference. - : International Measurement Confederation (IMEKO). ; , s. 85-91
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Konferensbidrag (refereegranskat)abstract
- Heating, ventilation, and air conditioning (HVAC) is the technology of indoor and vehicular environmental comfort. The objectives of HVAC systems are to provide an acceptable level of occupancy comfort and process function, to maintain good indoor air quality, and to keep system costs and energy requirements to a minimum. Performing a reliability prediction provides an awareness of potential equipment degradation during the equipment life cycle. Reliability under a range of conditions is one of the most important requirements to guarantee in HVAC installed on trains. Predicting the reliability of mechanical equipment requires the consideration of its exposure to the environment and subjection to a wide range of stress levels such as impact loading. Often analysist find an unavailability of failure data in handbooks and problems for acquiring data for mechanical components, so the mentioned problems demonstrates the need for reliability prediction models. The paper deals with a HVAC installed on a high-speed train and evaluates the failure rates through the failure rate models suggested by the handbooks in order to assess a model which includes all the mechanical parts.
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| 2. |
- Catelani, Marcantonio, et al.
(författare)
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Estimate the useful life for a heating, ventilation, and air conditioning system on a high-speed train using failure models
- 2021
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Ingår i: Acta IMEKO. - : International Measurement Confederation (IMEKO). - 0237-028X. ; 10:3, s. 100-107
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Tidskriftsartikel (refereegranskat)abstract
- Heating, ventilation, and air conditioning (HVAC) is a widely used system used to guarantee an acceptable level of occupancy comfort, to maintain good indoor air quality, and to minimize system costs and energy requirements. If failure data coming from company database are not available, then a reliability prediction based on failure rate model and handbook data must be carried out. Performing a reliability prediction provides an awareness of potential equipment degradation during the equipment life cycle. Otherwise, if field data regarding the component failures are available, then classical reliability assessment techniques such as Fault Tree Analysis and Reliability Block Diagram should be carried out. Reliability prediction of mechanical components is a challenging task that must be carefully assessed during the design of a system. For these reasons, this paper deals with the reliability assessment of an HVAC using both failure rate model for mechanical components and field data. The reliability obtained using the field data is compared to the one achieved using the failure rate models in order to assess a model which includes all the mechanical parts. The study highlights how it is fundamental to analyze the reliability of complex system integrating both field data and mathematical model.
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| 3. |
- Catelani, Marcantonio, et al.
(författare)
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FMECA assessment for railway safety-critical systems investigating a new risk threshold method
- 2021
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Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 9, s. 86243-86253
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Tidskriftsartikel (refereegranskat)abstract
- This paper develops a Failure Mode, Effects and Criticality Analysis (FMECA) for a heating, ventilation and air conditioning (HVAC) system in railway. HVAC is a safety critical system which must ensure emergency ventilation in case of fire and in case of loss of primary ventilation functions. A study of the HVAC’s critical areas is mandatory to optimize its reliability and availability and consequently to guarantee a low operation and maintenance cost. The first part of the paper describes the FMECA which is performed and reported to highlight the main criticalities of the HVAC system under analysis. Secondly, the paper deals with the problem of the evaluation of a threshold risk value, which can distinguish negligible and critical failure modes. Literature barely considers the problem of an objective risk threshold estimation. Therefore, a new analytical method based on finite difference is introduced to find a univocal risk threshold value. The method is then tested on two Risk Priority Number datasets related to the same HVAC. The threshold obtained in both cases is a good tradeoff between the risk mitigation and the cost investment for the corrective actions required to mitigate the risk level. Finally, the threshold obtained with the proposed method is compared with the methods available in literature. The comparison shows that the proposed finite difference method is a well-structured technique, with a low computational cost. Furthermore, the proposed approach provides results in line with the literature, but it completely deletes the problem of subjectivity.
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| 4. |
- Catelani, Marcantonio, et al.
(författare)
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Optimizing Maintenance Policies for a Yaw System Using Reliability-Centered Maintenance and Data-Driven Condition Monitoring
- 2020
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 69:9, s. 6241-6249
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Tidskriftsartikel (refereegranskat)abstract
- System downtime and unplanned outages massively affect plant productivity; therefore, the reliability, availability, maintainability, and safety (RAMS) disciplines, together with fault diagnosis and condition monitoring (CM), are mandatory in energy applications. This article focuses on the optimization of a maintenance plan for the yaw system used in an onshore wind turbine (WT). A complete reliability-centered maintenance (RCM) procedure is applied to the system to identify which maintenance action is the optimal solution in terms of cost, safety, and availability. The scope of the research is to propose a new customized decision-making diagram inside the RCM assessment to reduce the subjectivity of the procedure proposed in the standard and save the cost by optimizing maintenance decisions, making the projects more cost-efficient and cost-effective. This article concludes by proposing a new diagnostic method based on a data-driven CM system to efficiently monitor the health and detect damages in the WT by means of measurements of critical parameters of the tested system. This article highlights how a reliability analysis, during the early phase of the design, is a very helpful and powerful means to guide the maintenance decision and the data-driven CM.
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| 5. |
- Catelani, Marcantonio, et al.
(författare)
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Reliability improvement of wind turbine control system based on standby redundancy
- 2019
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Ingår i: ISSE 2019 - 5th IEEE International Symposium on Systems Engineering. - : IEEE. - 9781728117836
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Reliability analysis is widely used in many industrial fields to predict the remaining life of complex systems by assessing their current health status. This paper deals with one of the best-known techniques for reliability analysis: the reliability block diagram. This method models the reliability of the system based on the system's architecture and the reliability of its components. The work analyses the control system of a 2MW wind turbine, proposing two different reliability models. The first draws on a standard control system architecture. The second introduces a cold standby redundancy architecture for the data acquisition subsystem and a warm standby redundancy architecture for the power supply subsystem. With these configurations, it is possible to improve the system reliability by neglecting some failure modes because one of the branches of the redundant configuration will be either inactive or partially active.
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| 6. |
- Catelani, Marcantonio, et al.
(författare)
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Risk Assessment of a Wind Turbine : A New FMECA-Based tool with RPN threshold estimation
- 2020
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Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 8, s. 20181-20190
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Tidskriftsartikel (refereegranskat)abstract
- A wind turbine is a complex system used to convert the kinetic energy of the wind into electrical energy. During the turbine design phase, a risk assessment is mandatory to reduce the machine downtime and the Operation & Maintenance cost and to ensure service continuity. This paper proposes a procedure based on Failure Modes, Effects, and Criticality Analysis to take into account every possible criticality that could lead to a turbine shutdown. Currently, a standard procedure to be applied for evaluation of the risk priority number threshold is still not available. Trying to fill this need, this paper proposes a new approach for the Risk Priority Number (RPN) prioritization based on a statistical analysis and compares the proposed method with the only three quantitative prioritization techniques found in literature. The proposed procedure was applied to the electrical and electronic components included in a Spanish 2 MW on-shore wind turbine.
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| 7. |
- Ciani, Lorenzo, et al.
(författare)
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Improving context awareness reliability estimation for a wind turbine using an RBD model
- 2019
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Ingår i: 2019 IEEE International Instrumentation and Measurement Technology conference (I2MTC). - New York : IEEE. ; , s. 245-250
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Konferensbidrag (refereegranskat)abstract
- All devices are fabricated from materials that degrade with time. Degradation will continue until some critical device parameter can no longer meet the required specification for proper device functionality. Reliability estimation can assess the current health of a system and predict its remaining life. This kind of analysis is critical to improve safety, optimize scheduled maintenance, reduce life-cycle cost and minimize down time. This work analyses the reliability of a 2NIW wind turbine using the Reliability Block Diagram method. The paper compares the reliability estimated in standard environmental conditions and the reliability evaluated considering the real temperature and humidity values acquired using a SCADA system.
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| 8. |
- Ciani, Lorenzo, et al.
(författare)
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Improving Human Reliability Analysis for railway systems using fuzzy logic
- 2021
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Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 9, s. 128648-128662
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Tidskriftsartikel (refereegranskat)abstract
- The International Union of Railway provides an annually safety report highlighting that human factor is one of the main causes of railway accidents every year. Consequently, the study of human reliability is fundamental, and it must be included within a complete reliability assessment for every railway-related system. However, currently RARA (Railway Action Reliability Assessment) is the only approach available in literature that considers human task specifically customized for railway applications. The main disadvantages of RARA are the impact of expert’s subjectivity and the difficulty of a numerical assessment for the model parameters in absence of an exhaustive error and accident database. This manuscript introduces an innovative fuzzy method for the assessment of human factor in safety-critical systems for railway applications to address the problems highlighted above. Fuzzy logic allows to simplify the assessment of the model parameters by means of linguistic variables more resemblant to human cognitive process. Moreover, it deals with uncertain and incomplete data much better than classical deterministic approach and it minimizes the subjectivity of the analyst evaluation. The output of the proposed algorithm is the result of a fuzzy interval arithmetic, α-cut theory and centroid defuzzification procedure. The proposed method has been applied to the human operations carried out on a railway signaling system. Four human tasks and two scenarios have been simulated to analyze the performance of the proposed algorithm. Finally, the results of the method are compared with the classical RARA procedure underline compliant results obtain with a simpler, less complex and more intuitive approach.
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| 9. |
- Ciani, Lorenzo, et al.
(författare)
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Reliability evaluation of an HVAC ventilation system with FTA and RBD analysis
- 2020
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Ingår i: 2020 International Symposium on Systems Engineering (ISSE) Proceedings. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- Rail industry is rapidly developing, and rail becomes ever more viable in a wide range of regions. Therefore, the passenger experience and comfort has become a major concern for operators in the world. Heating, ventilation and air conditioning systems are used in railways to provide passengers thermal comfort and proper air motion. The ventilation system is one of the main elements of the system. Its components include both mechanical and electronic devices. All components are subjected to stress, and this tends to reduce their life cycle; the reliability of the ventilation system must be evaluated to plan and schedule appropriate maintenance activities. The paper evaluates reliability of the ventilation system using fault tree analysis and a reliability block diagram. Both techniques analyse data qualitatively; moreover, with specific algorithms they also provide quantitative results in term of reliability and probability of system failure. The paper compares the two reliability evaluation methods to verify their accuracy.
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| 10. |
- Fornlöf, Veronica, et al.
(författare)
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Maintenance, prognostics and diagnostics approaches for aircraft engines
- 2016
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Ingår i: 3rd IEEE International Workshop on Metrology for Aerospace, MetroAeroSpace 2016. - : IEEE. - 9781467382922 - 9781467382939 ; , s. 403-407
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Konferensbidrag (refereegranskat)abstract
- In avionics application one of the most important competition factors is the reliability, given that the failure occurrence may leads to a critical state for the functioning of the aircraft. Different maintenance, prognostics and diagnostics approaches are possible with the final aim to optimize both system's availability and safety. Aircraft engines represent a safety critical part of the airplane. For this reason it is a key issue to allocate the proper amount of maintenance at each individual maintenance event. In this paper a mathematical replacement model is proposed to guarantee that the correct amount of maintenance is performed.
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