| 1. |
- Misiunas, Dalius, et al.
(författare)
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Assessing water mains condition using hydraulic transients
- 2007
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Ingår i: Proceedings of the Institution of Civil Engineers. Water Management. - : Thomas Telford Ltd.. - 1741-7589 .- 1751-7729. ; 160:2, s. 89-94
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the potential of using controlled hydraulic transients for non-intrusive assessment of the internal condition of water transmission pipelines. Deterioration of pipelines is a natural process. An effective tool for evaluating the state of pipeline interiors could be extremely useful for planning rehabilitation or identifying critical points in a system. A non-intrusive technique for evaluating the state of the internal surface of a pipeline is introduced. The total length of the pipeline was divided into a number of segments and the condition of each segment assessed based on the transient response corresponding to that interval. In addition to quantification of the deterioration level of different sections of the pipeline, critical points were identified where closer investigation was suggested. The proposed technique, although in an early stage of development, was tested on a real pipeline.
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| 2. |
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| 3. |
- Misiunas, Dalius
(författare)
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Burst Detection and Location in Pipelines and Pipe Networks - With Application in Water Distribution
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sudden pipe bursts occur in high-pressure water transmission pipelines and water distribution networks. The consequences of these bursts can be very expensive due to the outage time while the burst pipe is repaired, the cost of repair, and damage to surrounding property and infrastructure. As a result, it is advantageous to minimise the detection and location time after the burst occurs. Currently, there is no effective solution for the burst detection and location problem in water distribution systems. The applications in oil and gas pipelines and pipe networks show the advantages of continuous monitoring. A number of techniques are used to determine the location and size of a burst. One of the most promising approaches is fluid transient modelling and analysis. Pressure transient analysis has also been successfully applied for detection and location of existing leaks. A sudden pipe burst creates a negative pressure wave that travels in both directions away from the burst point. The analysis of this wave is the main principle for the techniques presented in this thesis. Experiences from previous research suggest that, to achieve the best performance, single pipelines and pipe networks have to be treated separately. Thus, two different approaches for burst detection and location are presented. When a burst occurs in a pipeline, the burst-induced pressure wave travels in both directions along the pipeline and is reflected at the boundaries. Using a pressure trace measured at one location along the pipeline, the timing of the initial and reflected burst-induced waves determines the location of the burst. The presented continuous monitoring technique uses the modified two-sided cumulative sum (CUSUM) algorithm to detect abrupt changes in the pressure data caused by the pipe break. The results from both laboratory and field pipelines are used to verify the proposed method. Different burst and measurement locations are tested. The results are promising for burst detection and location in real systems. In the network case, continuous pressure measurements at two locations are analysed. The burst detection and location algorithm is based on the difference between the arrival times of the burst-induced pressure wave at each measurement point and on the measured wave magnitude. The arrival times are determined automatically in real time. A method for determining optimal measurement locations is also presented. Results from numerical simulations show that the proposed technique has potential as a tool for effective detection and location of bursts in real pipe networks. Most transient-based techniques use transient modelling for analysis or validation. The development of a transient model comprises part of the work presented in this thesis. The Method of Characteristics is used to solve the governing unsteady flow equations. Models for unsteady friction, leakage and burst are included. The model is used to validate the results of burst detection and location. iv
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| 4. |
- Misiunas, Dalius, et al.
(författare)
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Burst detection and location in water distribution networks
- 2005
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Ingår i: Water Supply. - 1606-9749. ; 5:3-4, s. 71-80
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Konferensbidrag (refereegranskat)abstract
- An algorithm for the detection and location of sudden bursts in water distribution networks combining both continuous monitoring of pressure and hydraulic transient computation is presented. The approach is designed for medium and large bursts that are the result of the sudden rupture of the pipe wall or other physical element in the network and are accompanied by the transient pressure wave that propagates throughout the network. The burst-induced transient wave arrival times and magnitudes measured at two or more points are used to find the location of a burst. The wave arrival times and magnitudes are detected using the modified cumulative sum (CUSUM) change detection test. Results of validation on a real network show the potential of the proposed burst detection and location technique to be used in water distribution systems.
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| 5. |
- Misiunas, Dalius, et al.
(författare)
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Burst detection and location in water transmission pipelines
- 2005
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Ingår i: EWRI 2005: Impacts of Global Climate Change. - Reston, VA : American Society of Civil Engineers.
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Konferensbidrag (refereegranskat)abstract
- This paper presents results from testing of a burst detection and location technique on a water transmission pipeline. The primary targets of the method are medium and large bursts that are the result of a sudden rupture of a pipe wall or other physical element in the pipeline system. The technique is based on the continuous monitoring of the pressure in the pipeline combined with a hydraulic transient modeling. Analysis of a burst-induced pressure transient wave and its reflections from the pipeline boundaries is used to derive the location and size of the burst. The method has earlier demonstrated promising results on a laboratory pipeline and a dead-end branch of a real water distribution network. Results presented here show that the approach has a potential to be used for burst detection and location in long transmission pipelines. Bursts of different sizes, locations and opening times were successfully detected and located. Different operational regimes of the pipeline were considered. The technique could help to minimize the response time to the pipe failure and therefore reduce the losses associated with a burst and improve reliability of the pipeline operation.
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| 6. |
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| 7. |
- Misiunas, Dalius
(författare)
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Failure Monitoring and Asset Condition Assessment in Water Supply Systems
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, different aspects of failure management in urban water supply systems are discussed. As assets are getting older, the number of pipe failures is increasing and an efficient failure management strategy becomes important. Two types of failure management strategies can be applied: proactive asset condition assessment and reactive failure detection and location. Currently available condition assessment techniques cannot be extensively applied in water supply systems due to high cost and slow speed of inspection. Existing failure detection and location approaches do not allow for quick reaction to failures. Automatic failure monitoring and systematic asset condition assessment methods are presented in this thesis. Due to the different topology and hydraulic characteristics of the transmission (pipelines) and distribution (network) components of a water supply system, separate failure detection and location techniques are proposed. For both pipeline and network cases, two types of failures are considered - sudden pipe ruptures and breaks that develop over a longer period of time. For the pipeline case, a periodical leak diagnosis system based on transient response difference monitoring, is presented together with a burst monitoring, detection and location system, which is designed for rapid reaction to sudden pipeline ruptures. A single continuous pressure monitoring station is sufficient to detect and locate a failure along the whole length of a pipeline. For the network case, two continuous failure monitoring approaches are developed, which are based on steady-state (first method) and unsteady-state (second method) analysis. Continuous monitoring of the pressure is performed at a number of locations within the network. The optimal placement of pressure monitoring stations, limits of burst sizes that will be detected, uncertainty of the results and implementation aspects are discussed for both approaches. A transient-analysis-based low-cost, long-range nondestructive pipe condition assessment technique is presented that can be used as a proactive failure management tool and for rehabilitation planning in water transmission pipelines. A comparative evaluation of different pipeline sections can be made and critical sections with a high degree of deterioration can be identified. Finally, a transient-based methodology is presented, which is designed to test the seal quality of inline valves that are used to isolate pipe failures. The techniques presented in this thesis contribute to different points in the pipe asset management cycle and can improve reliability, availability, safety and efficiency of the urban water supply.
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| 8. |
- Misiunas, Dalius, et al.
(författare)
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Failure monitoring in water distribution networks
- 2006
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 53:4-5, s. 503-511
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Tidskriftsartikel (refereegranskat)abstract
- An algorithm for the burst detection and location in water distribution networks based on the continuous monitoring of the flow rate at the entry point of the network and the pressure at a number of points within the network is presented. The approach is designed for medium to large bursts with opening times in the order of a few minutes and is suitable for networks of relatively small size, such as district metered areas (DMAs). The burst-induced increase in the inlet flow rate is detected using the modified cumulative sum (CUSUM) change detection test. Based on parameters obtained from the CUSUM test, the burst is simulated at a number of burst candidate locations. The calculated changes in pressure at the pressure monitoring points are then compared to the measured values and the location resulting in the best fit is selected as the burst location. The EPANET steady-state hydraulic solver is utilised to simulate the flows and pressures in the network. A sensitivity-based sampling design procedure is introduced to find the optimal positions for pressure monitoring points. The proposed algorithm is tested on a case study example network and shows potential for burst detection and location in real water distribution systems.
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