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Dissertations / Theses on the topic 'Pipe system and leak detection'
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1
Chatzigeorgiou, Dimitris M. "A reliable & autonomous robotic in-pipe leak detection system." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100118.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 145-151).
Leaks are the major factor for unaccounted losses in every pipe network around the world (oil, gas or water). In most cases the deleterious effects associated with the occurrence of leaks may present serious economical and health problems. Therefore, leaks must be quickly detected, located and repaired. Unfortunately, most state-of-the-art leak detection systems are of limited applicability, lack in reliability or depend on user experience for data interpretation. In this dissertation we present a new, autonomous, in-pipe, leak sensing system; the "MIT Leak Detector". The proposed system is able to perform autonomous leak detection in pipes and, thus, eliminates the need for user experience. In addition, the sensing methodology under consideration is independent of pipe material and surrounding medium, thus it is widely applicable. As shown in the experimental section of the thesis, the detection principle proves to be very reliable and sensitive to small leaks in pipes. Last but not least, the robotic system is equipped with intelligence in order to use the acquired sensor signals to estimate the leak size and flow rate without user intervention. We start the thesis by describing the fundamental concept behind detection and present the proposed design. The detection principle in based on the presence of a pressure gradient in the neighborhood of any leak in a pressurized pipe. This phenomenon is translated into force measurements via a carefully designed and instrumented mechanical embodiment. In addition, an analytic dynamic model of the robotic detector is derived. Further study and analysis show that the proposed system can sense leaks at any angle around the circumference of the pipe by utilizing two force measurements at specific locations. Finally, a prototype is built and experiments are conducted in controlled laboratory conditions in compressed air pipes.
by Dimitris M. Chatzigeorgiou.
Ph. D.
2
Choi, Changrak. "Robot design for leak detection in water-pipe systems." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70434.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 113-116).
Leaks are major problem that occur in the water pipelines all around the world. Several reports indicate loss of around 20 to 30 percent of water in the distribution of water through water pipe systems. Such loss of water represents critical waste of valuable resources, especially in countries such as Saudi Arabia where water is scarce. Moreover, leaks provide pathways for outside contaminants to enter into water pipe system which can deteriorate the quality of water and pose health risks to those drink from it. Considering these negatives, the importance of detecting where the leaks occur within vast network of water pipe system cannot be overemphasized. Further, for accurate and effective detection of the leaks, an in-pipe approach is taken which differs from previous detection methods. This thesis is on the design of mobile robotic platform that carries the necessary sensor and travels inside the water pipe systems. To begin with, experiments were carried out to investigate the suitability of using acoustic sensor to detect the leaks and favorable results were obtained. Then design specification of the mobile robotic platform that will carry the sensor is discussed with brief description of each components of the robot given. As components for the mobile robotic platform, a rigid-flexible robotic joint is developed that enables the robot to travel through bends and turns. Further, a novel braking mechanism using permanent magnet is presented. The mechanism results in a friction controllable leg that can be used to slow down and control the speed of robot in the presence of water flow. Finally, possible candidates for propulsion unit are discussed and evaluated with guidance for future work to be progressed.
by Changrak Choi.
S.M.
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Chatzigeorgiou, Dimitris M. "Analysis and design of an in-pipe system for water leak detection." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62529.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 131-133).
Leaks are a major factor for unaccounted water losses in almost every water distribution network. Pipeline leak may result, for example, from bad workmanship or from any destructive cause, due to sudden changes of pressure, corrosion, cracks, defects in pipes or lack of maintenance. The problem of leak becomes even more serious when it is concerned with the vital supply of fresh water to the community. In addition to waste of resources, contaminants may infiltrate into the water supply. The possibility of environmental health disasters due to delay in detection of water pipeline leaks have spurred research into the development of methods for pipeline leak and contamination detection. This thesis is on the analysis and design of a floating mobile sensor for leak detection in water distribution pipes. This work covers the study of two modules, namely a "floating body" along with its "sensing module". The Mobility Module or the floating body was carefully studied and designed using advanced CFD techniques to make the body as non-invasive to the flow as possible and to avoid signal corruption. In addition, experiments were carried out to investigate the effectiveness of using in-pipe measurements for leak detection in plastic pipes. Specifically, acoustic signals due to simulated leaks were measured and studied for designing a detection system to be deployed inside water networks of 100mm pipe size.
by Dimitris M. Chatzigeorgiou.
S.M.
4
Covas, DiÌdia Isabel Cameira. "Inverse transient analysis for leak detection and calibration of water pipe systems modelling special dynamic effects." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406338.
Full text
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Saleeby, Kyle Scott. "Design of soft-body robot with wireless communication for leak detection in large diameter pipe systems." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112547.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
Water leaks pose a major problem of efficiency and cost to municipalities and industries that cover significant area. While current commercial methods to address these problems do not provide convenient or low cost methods to detect leaks, a soft-body pipe leak detection robot has been developed to traverse small, 50mm diameter water pipe systems. This robot has proven to be effective in small diameter pipes, but its scalability for large diameter pipes is unknown. The focus of this thesis is to scale up the leak detection robot for 300mm diameter pipes and fabricate a robot prototype. In particular, the relationship between the shape of the robot and its maneuverability was explored, such that it was designed to passively travel through the pipe, driven by water flow. The robot was designed to successfully pass through changes in pipe diameter, pipe bends, and through partially clogged regions. To detect and distinguish pipe leaks from other debris in the pipe, two sensors were integrated in the robot. Experimental testing was conducted with the robot to verify functionality of its leak detection sensors. Supporting electronics were also implemented to wirelessly charge and communicate with the robot.
by Kyle Scott Saleeby.
S.B.
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Nelson, Berg Joakim, and Jonathan Lee. "A pre-study on the compressed air system at Ljunghaell AB." Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-25648.
Full textAbstract:
The Swedish industry uses large volumes of compressed air. The compressed air process isenergy intensive and creates large amounts of excess heat. It is therefore important to utilizethe excess heat, optimize the operation of the compressors and to have a regular maintenanceon the system. This thesis is a pre-study to make a compressed air system energy efficient andis done in collaboration with Ljunghäll AB. Ljunghäll AB is one of Northern Europe's leadingdie casting companies and are located in Södra Vi, Sweden. The purpose is to describe andmap the compressed air system in the old part of the facility in Södra Vi. The thesis will alsogive an explanation of how Ljunghäll AB can improve the compressed air system. Providethem suggestions for energy savings and lower the environmental impact of production. Theobjective of the thesis is to create an understanding of how improvements in the compressedair system can be done by studying the operation, compressor, pipe system and leak detecting.The economic aspects of the solutions together with the effect of noise and engine operationof the compressors have not been taken into consideration. To reach improvement measures avisit to the facility in Södra Vi was made, where measuring and mapping was executed andthen compared with earlier studies and literature. The conclusions of the thesis show thatLjunghäll AB has a good operation and control of the compressors, through the variable speeddrive and steering system. It also showed that the choice of the existing compressors are goodfor their compressed air usage. The study also resulted in the following suggestions for theenergy efficiency and lowering of the environmental impact of production at Ljunghäll AB’scompressed air system: Water heat recovery, replacement of old pipes, cover the leakage,regular maintenance of compressors and fittings, training in compressed air for workers,centralized compressor central and sectioning of the pipe system.
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Garay, Luis I. (Luis Ignacio). "Evaluating an experimental setup for pipe leak detection." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/85780.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (page 33).
An experimental setup with 4 inch inner diameter PVC pipe modules is designed to mimic a real life piping system in which to test possible leak detection mechanisms. A model leak detection mechanism is developed which consists of a ring with threads that follow the streamlines of the flow inside the pipes, allowing for a visualization of the flow patterns. Two experiments were conducted in order to test the effect of the leak on the threads of the detection mechanism. The first experiment was successful in that the threads were clearly affected in the proximity of the leak; however, it was not realistic because of the lack of cross flow. The second experiment allowed for cross flow. On the other hand, this experiment failed in that the threads of the detection mechanism were not affected by the leak due to the small leak flow rate. A theoretical model of the second experimental setup is proposed in order to estimate how the exit hole diameter will affect the leak and outflow volumetric flow rates. From the model it is concluded that a small exit hole is needed to increase the leak flow rate; however this would reduce the cross flow rate inside the system to a value bellow real life conditions.
by Luis I. Garay.
S.B.
8
Kim, David Donghyun. "Flexible in-pipe leak detection sensor module design and fabrication." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101541.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 83-84).
Recent pipe bursts and explosions have caused not only financial losses but also a threat to public safety. Due to the recent incidents, governments have imposed strict laws with an increase in inspection regulation requirements. Large size networks make manual inspection of an entire complex system almost impossible. The need for autonomous automatic inspection systems is evident. A robust autonomous in-pipe leak detection robot was developed and reported in [1-5]. The developed system is able to accurately detect leaks in both pressurized gas and water pipes. This however was limited to 101.6mm (4in) internal diameter pipes. In practice, fouling of water pipes makes the internal pipe surface irregular. This thesis presents an analysis, design and experimental evaluation of a flexible detection system for pipes with large inner pipe diameter variation (80mm to 120mm). The system performance is evaluated through simulations and experiments. Experimental results show that the flexible sensor can detect leaks in pipes with simulated limescale. In addition, experiments were conducted to evaluate the effects of detector shift from the pipe centerline along with the effective area coverage of the leak by the sensor. The results show robust performance under large variations.
by David Donghyun Kim.
S.M.
9
Mittmann, Elizabeth(Elizabeth R. ). "Smart water network management with in-pipe leak detection robots." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122119.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 85-87).
In this thesis, I created methods and designs to implement smarter, more autonomous water distribution networks (WDNs) and also improved the robots which will travel within the WDN's pipes to better differentiate pipe leaks from bumps in the pipes. Starting from the unit of the in-pipe leak detection robot, I investigated ways to make its soft leak sensors able to differentiate between pulling (due to leaks) and bending (due to bumps), and showed how a new design of adding fabric to the soft sensor allows the sensors to differentiate bending from pulling. Zooming out to the larger picture I looked at feasible ways these robots could be used throughout a cities' WDN, and created cost analyzes to compare futuristic methods of WDN management with current methods of district metered areas (DMAs). However, going from our current state of minimally instrumented pipes, to pipes with many valves to direct in-pipe inspection robots is a big leap, and thus I also created a method to help evaluate the cost trade-off of valve placement and the optimal spots for adding valves in the case where it was ideal to place valves on only some of the intersections of the WDN..
by Elizabeth Mittmann.
S.M.
S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Moore, Frederick M. "Further development of an in-pipe leak detection sensor's mobility platform." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83830.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (page 68).
Water leakage is a major global problem and smaller sized leaks are difficult to find despite their prevalence in most water distribution systems. Previous attempts to develop a mobility platform for a sensor in use in such a pipe by the MIT Mechatronics lab have been met with less than desirable results and a new design was needed for functionality. A more integrated, streamlined, and powerful mobility platform was developed from the original design specifications and then constructed according to newly developed techniques. This new mobility platform was then evaluated in a series of tests to determine the experimental drag and thrust, values that would determine its functionality, as well as flow characteristics and waterproof functionality. The new platform was found to be waterproof, have a maximum thrust of 3.47 N and drag at the desired speed of 1.815 N. It was also found to move through a pipe at a speed of 0.9667 m/s, despite some stability concerns.
by Frederick M. Moore.
S.B.
11
Wu, You S. M. Massachusetts Institute of Technology. "Design and fabrication of a maneuverable robot for in-pipe leak detection." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92113.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 115-116).
Leaks in pipelines have been causing a significant amount of financial losses and serious damages to the community and the environment. The recent development of in-pipe leak detection technologies at Massachusetts Institute of Technology made it possible to find the accurate location of leaks in underground pipes. However, like all in-pipe leak sensors, they need a maneuverable robot to transport them inside the pipes. In the pipe networks, the robot must be able to perform complicated movements such as sharp turns at Tee junctions. This thesis presents a solution to this in-pipe leak detection challenge and the design and a prototype of such robot. The design and fabrication of a small in-pipe swimming robot of high maneuverability is presented. The robot is equipped with a pair of customized micro RIM driven propellers which provide a powerful and safe propulsion. A prototype robot that operates in 10 cm diameter pipes is built and tested experimentally. This robot demonstrated experimentally abilities to follow straight lines and make turns with radii smaller than a fraction of its body length.
by You Wu.
S.M.
12
Iwanaga, Mauricio Kiotsune. "Development of a virtual pipe test rig for testing acoustic correlators for leak detection in buried water pipes /." Ilha Solteira, 2019. http://hdl.handle.net/11449/183466.
Full textAbstract:
Orientador: Michael John BrennanResumo: Vazamentos em tubulações de água enterradas são considerados um importante problema já que uma grande quantidade de água é desperdiçada entre a planta de tratamento e os consumidores. Para lidar com tal problema, companhias de saneamento utilizam dispostivos para localizar vazamentos nas tubulações. Dispositivos de escuta e correlacionadores de ruídos são os equipamentos mais utilizados em campo pelas companhias de sanemaneto ao redor do mundo. Correlacionadores de ruídos são dispositivos usados na localização de vazamentos em tubulações enterradas através da estimativa do tempo de atraso entre os sinais medidos pelos sensores posicionados em ambos os lados de um suposto vazamento. Uma vez que as companhias de saneamento devem decidir qual tipo de correlacionador é o mais compatível com a sua rede de tubulações, elas devem realizar alguns testes para ajudar em tal decisão e para treinar os funcionários que operam estes dispositivos, os quais devem ser expostos a diferentes condições, tais como tubos de diferentes materiais e geometrias, diferentes tipos de solo, vazamentos com diferentes intensidades, etc. Neste contexto, o principal objetivo desta pesquisa é contribuir com esta necessidade através da elaboração de um dispositivo de bancada capaz de reproduzir as vibrações de um tubo causadas por um vazamento. O dispositivo, chamado de simulador virtual de vazamentos, é composto por um computador, um amplificador de potência com dois canais e dois shakers. Ruídos de vazamento... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Leakage in buried water pipes is an important problem since a large amount of water is wasted between the treatment plant and the consumers. To deal with such a problem, water companies have used some devices to localize leaks in the pipe network. Listening devices and leak noise correlators are the most popular equipment used in the field by the water companies around the world. Leak noise correlators are important devices used to localize leaks in buried pipes by calculating the time delay between the signals measured by the sensors positioned either side of a suspected leak. Since water companies have to decide which leak noise correlator is more suitable for each pipe network, they have to carry out some field tests to assist in this decision and to train the personnel that handles such a device, which ideally must be exposed to different conditions, such as pipes with different materials and geometries, different types of soil, different leak strengths, etc. The main objective of this research project is to contribute with the necessity of the water companies by designing an indoor bench-top device capable to reproduce the pipe vibrations generated by a leak in the field. The device, called virtual pipe test rig, comprises a computer and a dual-channel power amplifier supplying two shakers. In the computer, leak noise is synthesized by using a model of a buried leaking pipe implemented using the software Matlab®. Since the systems, composed by the power amplifiers and th... (Complete abstract click electronic access below)
Mestre
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Monteiro, Michele Roberta Pedroso dos Santos. "Estudo do método de resposta em freqüência para localizar e quantificar vazamentos através do monitoramento de pressões e vazões em adutoras de água tratada." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-08122006-160023/.
Full textAbstract:
Neste trabalho são apresentados diversos métodos de localização de vazamentos, desde as técnicas e equipamentos mais elementares, como a inspeção visual e o geofone mecânico, até o uso dos sofisticados armazenadores de ruídos e de modelação computacional. Algumas dessas técnicas são amplamente difundidas e largamente utilizadas pelas empresas de saneamento, outras porém, constituem-se em ótimas promessas para o aperfeiçoamento do controle das perdas físicas nos sistemas de abastecimento. É dada ênfase na utilização do diagrama de resposta em freqüência para localizar e quantificar vazamentos, com especial aplicação às adutoras de água tratada. A técnica de utilização da resposta em freqüência desenvolvida por Lee et al. (2005) é esmiuçada, inclusive acerca do impacto que um vazamento impõe ao diagrama de resposta em freqüência. São abordadas as formas de obtenção do referido diagrama, tanto do ponto de vista do modelo matemático e computacional, quanto dos ensaios de campo necessários.This work presents some methods for leak location, from de most elementary techniques and equipments, as visual inspection and mechanical geophone, until using sophisticated noise data-logger and computational modeling. Some of these techniques are very well issued and largely used by water companies, but others play excellent promises for the improvement of leak control in systems of water supply. The pattern of the frequency response diagram is used for leak location and quantification, with special application in drinking water pipelines. The frequency response technique developed by Lee et al. (2005) is studied in details, including the impact produced by the leak on the frequency response diagram. The ways to obtain the frequency response diagram, by using mathematical and computational models or necessary field data survey, are also discussed.
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Coimbatore, Subramanian Shankar Ram. "A diagnostic system for air brakes in commercial vehicles." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5857.
Full textAbstract:
This dissertation deals with the development of a model-based diagnostic system
for air brake systems that are widely used in commercial vehicles, such as trucks,
tractor-trailers, buses, etc. The performance of these brake systems is sensitive to
maintenance and hence they require frequent inspections. Current inspection techniques
require an inspector to go underneath a vehicle to check the brake system
for possible faults, such as leaks, worn brake pads, out-of-adjustment of push rods,
etc. Such inspections are time consuming, labor intensive and difficult to perform
on vehicles with a low ground clearance. In this context, the development of an onboard/
handheld diagnostic tool for air brakes would be of significant value. Such a
tool would automate the brake inspection process, thereby reducing the inspection
time and improving the safety of operation of commercial vehicles. In this dissertation,
diagnostic schemes are developed to automatically detect two important and
prevalent faults that can occur in air brake systems â leaks and out-of-adjustment of
push rods.
These diagnostic schemes are developed based on a nonlinear model for the pneumatic
subsystem of the air brake system that correlates the pressure transients in the
brake chamber with the supply pressure to the treadle valve and the displacement of the treadle valve plunger. These diagnostic schemes have been corroborated with
data obtained from the experimental facility at Texas A&M University and the results
are presented.
The response of the pneumatic subsystem of the air brake system is such that it
can be classified as what is known as a âÂÂSequential Hybrid SystemâÂÂ. In this dissertation,
the term âÂÂhybrid systemsâ is used to denote those systems whose mathematical
representation involves a finite set of governing ordinary differential equations corresponding
to a finite set of modes of operation. The problem of estimating the push
rod stroke is posed as a parameter estimation problem and a transition detection
problem involving the hybrid model of the pneumatic subsystem of the air brake system.
Also, parameter estimation schemes for a class of sequential hybrid systems are
developed. The efficacy of these schemes is illustrated with some examples.
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Vijayaraghavan, Vishnu Karthik. "Methodology to quantify leaks in aerosol sampling system components." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1195.
Full textAbstract:
Filter holders and continuous air monitors (CAMs) are used extensively in the nuclear industry. It is important to minimize leakage in these devices and in recognition of this consideration, a limit on leakage for sampling systems is specified in ANSI/HPS N13.1-1999; however the protocol given in the standard is really germane to measurement of significant leakage, e.g., several percent of the sampling flow rate. In the present study, a technique for quantifying leakage was developed and that approach was used to measure the sealing integrity of a CAM and two kinds of filter holders. The methodology involves use of sulfur hexafluoride as a tracer gas with the device being tested operated under dynamic flow conditions. The leak rates in these devices were determined in the pressure range from 2.49 kPa (10 In. H2O) vacuum to 2.49 kPa (10 In. H2O) pressure at a typical flow rate of 56.6 L/min (2 cfm). For the two filter holders, the leak rates were less than 0.007% of the nominal flow rate. The leak rate in the CAM was less than 0.2% of the nominal flow rate. These values are well within the limit prescribed in the ANSI standard, which is 5% of the nominal flow rate. Therefore the limit listed in the ANSI standard should be reconsidered as lower values can be achieved, and the methodology presented herein can be used to quantify lower leakage values in sample collectors and analyzers. A theoretical analysis was also done to determine the nature of flow through the leaks and the amount of flow contribution by the different possible mechanisms of flow through leaks.
16
Mounce, Stephen Robert. "A hybrid neural network fuzzy rule-based system applied to leak detection in water pipeline distribution networks." Thesis, University of Bradford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.695062.
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Kleczyk, Ewa Jadwiga. "Incidence and Costs of Pinhole Leak Corrosion and Corporate Cost of Capital Borrowing." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29901.
Full textAbstract:
The first part of this doctorate dissertation examines the factors influencing the occurrence and costs of pinhole leak corrosion as well as the household decisions for corrosion prevention and plumbing material selection. Three mail surveys of households were used to elicit the experiences with leaks as well as the optimal corrosion prevention and material choices. Probability modeling (i.e. MNL) and linear regression analysis were used to analyze survey responses. Pinhole leak occurrences were found associated with pipe type installed, property age, pipe failure history, and dwelling distance from a water treatment plant. The number and location of pinhole leaks in the dwelling and the pipe type are associated with the financial costs of pinhole leaks. The corrosion prevention choices as well as the plumbing materials depended on the risk of corrosion and cost associated with each option. Previous experiences with pinhole leak impacted the decision for household choices. Faster responses to pinhole leak outbreaks by utility managers and policymakers in terms of advising homeowners on the best ways of responding to leaks would assist homeowners in reducing costs of pinhole leak repairs and associated damages.
The second part of this document deals with the debt financing issues. Debt financing decisions are made simultaneously by lenders and borrowers. Since lenders are unable to observe directly the firms’ investment decisions, the banks offer contracts based up on firms’ observable characteristics (i.e. wealth and size) and the prevailing market conditions. When deciding on the financing decisions, firms also take into account the changes in macroeconomic variables in order to lower the cost of borrowing. As a result, the goal for this article is to examine empirically the hypothesis of the effect of the debt determinant as well as the macroeconomic variables on the debt maturity structure. A reduced form of the simultaneous financing decisions model is estimated by employing several OLS estimation methods. The empirical findings offer strong support for firms with few growth options, large, and of low quality having more long-term debt in their capital structure. There was, however, no clear support for the impact of macroeconomic variables on debt maturity as some variables were not statistically significant.Ph. D.
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Okeya, Olanrewaju Isaac. "Detection and localisation of pipe bursts in a district metered area using an online hydraulic model." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/33823.
Full textAbstract:
This thesis presents a research work on the development of new methodology for near-real-time detection and localisation of pipe bursts in a Water Distribution System (WDS) at the District Meters Area (DMA) level. The methodology makes use of online hydraulic model coupled with a demand forecasting methodology and several statistical techniques to process the hydraulic meters data (i.e., flows and pressures) coming from the field at regular time intervals (i.e. every 15 minutes). Once the detection part of the methodology identifies a potential burst occurrence in a system it raises an alarm. This is followed by the application of the burst localisation methodology to approximately locate the event within the District Metered Area (DMA). The online hydraulic model is based on data assimilation methodology coupled with a short-term Water Demand Forecasting Model (WDFM) based on Multi-Linear Regression. Three data assimilation methods were tested in the thesis, namely the iterative Kalman Filter method, the Ensemble Kalman Filter method and the Particle Filter method. The iterative Kalman Filter (i-KF) method was eventually chosen for the online hydraulic model based on the best overall trade-off between water system state prediction accuracy and computational efficiency. The online hydraulic model created this way was coupled with the Statistical Process Control (SPC) technique and a newly developed burst detection metric based on the moving average residuals between the predicted and observed hydraulic states (flows/pressures). Two new SPC-based charts with associated generic set of control rules for analysing burst detection metric values over consecutive time steps were introduced to raise burst alarms in a reliable and timely fashion. The SPC rules and relevant thresholds were determined offline by performing appropriate statistical analysis of residuals. The above was followed by the development of the new methodology for online burst localisation. The methodology integrates the information on burst detection metric values obtained during the detection stage with the new sensitivity matrix developed offline and hydraulic model runs used to simulate potential bursts to identify the most likely burst location in the pipe network. A new data algorithm for estimating the ‘normal’ DMA demand and burst flow during the burst period is developed and used for localisation. A new data algorithm for statistical analysis of flow and pressure data was also developed and used to determine the approximate burst area by producing a list of top ten suspected burst location nodes. The above novel methodologies for burst detection and localisation were applied to two real-life District Metred Areas in the United Kingdom (UK) with artificially generated flow and pressure observations and assumed bursts. The results obtained this way show that the developed methodology detects pipe bursts in a reliable and timely fashion, provides good estimate of a burst flow and accurately approximately locates the burst within a DMA. In addition, the results obtained show the potential of the methodology described here for online burst detection and localisation in assisting Water Companies (WCs) to conserve water, save energy and money. It can also enhance the UK WCs’ profile customer satisfaction, improve operational efficiency and improve the OFWAT’s Service Incentive Mechanism (SIM) scores.
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Lima, Simone Rodrigues. "Análise tempo-frequência de ondas acústicas em escoamentos monofásicos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-04022011-152245/.
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A presente dissertação tem como objetivo principal estudar a propagação acústica em escoamentos monofásicos. Para tal, são analisados sinais transientes de pressão fornecidos por sensores instalados em posições conhecidas na linha de teste, através do estudo de técnicas de análise de sinais, a fim de investigar se as variações do conteúdo espectral dos sinais são influenciadas pela ocorrência de vazamentos no duto. A análise dos sinais foi realizada nos planos temporal, frequencial, tempo-frequência e estatístico. Os resultados experimentais foram obtidos no oleoduto piloto do NETeF - Núcleo de Engenharia Térmica e Fluidos da USP - Universidade de São Paulo, com uma seção de testes com 1500 metros e diâmetro de 51,2 mm, com escoamento monofásico de água. Os resultados obtidos através da análise tempo-frequência mostraram-se satisfatórios, sendo esta técnica capaz de identificar a composição espectral instantânea de um sinal, ou seja, foi eficiente na identificação de picos de amplitude da frequência ao longo do eixo temporal. Além disso, a análise probabilística, através do desvio-padrão do sinal também mostrou-se eficiente exibindo uma disparidade significativa entre os sinais com e sem vazamento.The present dissertation reports on the study of the acoustic propagation in single-phase flow. It analyzes the transient signals provided by pressure sensors in known locations in the test line through the study of signal analysis techniques to investigate if the variations in spectral content of the signals are influenced by the occurrence of leaks in the pipe. The analysis of signals was performed in the time, frequency, time-frequency and statistical plans. The experimental results were obtained in a 1500 meter-long and 51.2 millimeter-diameter pilot pipeline at the Center of Thermal Engineering and Fluids, with single-phase flow of water. The results obtained by time-frequency analysis were satisfactory, allowing identifying the spectral composition of an instantaneous signal, i.e., the analysis was effective in identifying the frequency amplitude peaks along the time axis. Moreover, probabilistic analysis using the standard deviation of the signal was also efficient, displaying a significant disparity between the signals with and without leakage.
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Thantulage, Gishantha I. F. "Ant colony optimization based simulation of 3d automatic hose/pipe routing." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4282.
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This thesis focuses on applying one of the rapidly growing non-deterministic optimization algorithms, the ant colony algorithm, for simulating automatic hose/pipe routing with several conflicting objectives. Within the thesis, methods have been developed and applied to single objective hose routing, multi-objective hose routing and multi-hose routing. The use of simulation and optimization in engineering design has been widely applied in all fields of engineering as the computational capabilities of computers has increased and improved. As a result of this, the application of non-deterministic optimization techniques such as genetic algorithms, simulated annealing algorithms, ant colony algorithms, etc. has increased dramatically resulting in vast improvements in the design process. Initially, two versions of ant colony algorithms have been developed based on, respectively, a random network and a grid network for a single objective (minimizing the length of the hoses) and avoiding obstacles in the CAD model. While applying ant colony algorithms for the simulation of hose routing, two modifications have been proposed for reducing the size of the search space and avoiding the stagnation problem. Hose routing problems often consist of several conflicting or trade-off objectives. In classical approaches, in many cases, multiple objectives are aggregated into one single objective function and optimization is then treated as a single-objective optimization problem. In this thesis two versions of ant colony algorithms are presented for multihose routing with two conflicting objectives: minimizing the total length of the hoses and maximizing the total shared length (bundle length). In this case the two objectives are aggregated into a single objective. The current state-of-the-art approach for handling multi-objective design problems is to employ the concept of Pareto optimality. Within this thesis a new Pareto-based general purpose ant colony algorithm (PSACO) is proposed and applied to a multi-objective hose routing problem that consists of the following objectives: total length of the hoses between the start and the end locations, number of bends, and angles of bends. The proposed method is capable of handling any number of objectives and uses a single pheromone matrix for all the objectives. The domination concept is used for updating the pheromone matrix. Among the currently available multi-objective ant colony optimization (MOACO) algorithms, P-ACO generates very good solutions in the central part of the Pareto front and hence the proposed algorithm is compared with P-ACO. A new term is added to the random proportional rule of both of the algorithms (PSACO and P-ACO) to attract ants towards edges that make angles close to the pre-specified angles of bends. A refinement algorithm is also suggested for searching an acceptable solution after the completion of searching the entire search space. For all of the simulations, the STL format (tessellated format) for the obstacles is used in the algorithm instead of the original shapes of the obstacles. This STL format is passed to the C++ library RAPID for collision detection. As a result of using this format, the algorithms can handle freeform obstacles and the algorithms are not restricted to a particular software package.
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Araujo, Gabriell John Medeiros de. "Sistema de aquisi??o de dados para estudos de transiente de press?o e detec??o de vazamentos em oleodutos." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18536.
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Previous issue date: 2012-03-05In February 2011, the National Agency of Petroleum, Natural Gas and Biofuels (ANP) has published a new Technical Rules for Handling Land Pipeline Petroleum and Natural Gas Derivatives (RTDT). Among other things, the RTDT made compulsory the use of monitoring systems and leak detection in all onshore pipelines in the country. This document provides a study on the method for detection of transient pressure. The study was conducted on a industrial duct 16" diameter and 9.8 km long. The pipeline is fully pressurized and carries a multiphase mixture of crude oil, water and natural gas. For the study, was built an infrastructure for data acquisition and validation of detection algorithms. The system was designed with SCADA architecture. Piezoresistive sensors were installed at the ends of the duct and Digital Signal Processors (DSPs) were used for sampling, storage and processing of data. The study was based on simulations of leaks through valves and search for patterns that characterize the occurrence of such phenomena
Em fevereiro de 2011, a Ag?ncia Nacional de Petr?leo, G?s Natural e Biocombust?veis (ANP) publicou o novo Regulamento Tecnico de Dutos Terrestres para Movimenta??o de Petr?leo, Derivados e Gas Natural (RTDT). Entre outros aspectos, o RTDT tornou obrigat?rio o emprego de sistemas de monitoramento e detec??o de vazamentos em todos os dutos terrestres do pa?s. Este documento traz um estudo sobre o m?todo de detec??o por transiente de press?o. O estudo foi realizado num duto industrial de 16" de di?metro e 9,8 Km de extens?o. O duto e totalmente pressurizado e transporta uma mistura multif?sica de ?leo bruto, ?gua e g?s natural. Para a realiza??o do estudo, foi constru?da uma infraestrutura de aquisi??o de dados e valida??o de algoritmos de detec??o. O sistema foi concebido com arquitetura SCADA. Sensores piezoresistivos foram instalados nas extremidades do duto e Processadores Digitais de Sinais (DSPs) foram usados para a amostragem, armazenamento e processamento dos dados. O estudo se baseou na realiza??o de simula??es de vazamentos por meio de valvulas e busca por padr?es que caracterizassem a ocorr?ncia de tais fen?menos
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Tseng, Kuan-Hua, and 曾冠樺. "The Measurement of the Fluid Pipes of the Distributed Fiber Optic Leak Detection System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/42098756501256017162.
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碩士國立中山大學
電機工程學系研究所
90
The main frame of the distributed fiber optic leak detection system adopted the hybrid Mach-Zehnder & Sagnac interferomtric. We use the sensing fiber of In-Line frame to detect leak physical field. We can measure the position of the leak physical field through our sensing system and signal process system. In the cause of improving detective ability of leak detection system, we modify three elements of the system, including (1) the choice of the acoustic response of sensing fiber, (2) modification of the PZT phase modulator, and (3) modification of the PGC demodulator. The frame of our experiment is composed of the distributed fiber optic leak detection system and leak system of the fluid pipes. In which leak system of fluid pipes is designed the leaky frame of high-pressure fluid pipes. The main of experiment introduce the leak detection system to measure the leak acoustics of the fluid pipes. Then we can discuss the experimental result. The measurable minimum range of our distributed fiber optic leak detection system is3.3x10^-4(rad/√Hz), and the dynamic range is above 75 dB. The dynamic range of this system can improve the original system to above 15 dB.
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HSU, TSUNG-YAO, and 許琮堯. "Long-distance pipeline route mapping and magnetic leak detection system." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/26n2wn.
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碩士國立臺北科技大學
機電整合研究所
105
This study establish an intelligent underground pipeline inspection system and the purpose is to use motor drive force and media transmission force in the pipeline to support the carrier movement and we use MATLAB to analyze data about magnetic flux and map pipe diameter route in the 4-inch pipeline for research. In this study, the main principle is to detect magnetic leakage and draw the defect map. We combine the gyroscope and the acceleration sensor to carry out in the pipeline to know the defect location. Carrier is divided into three parts. The first part is that the positioning system equipped with jy61 chip to record carrier operating path and monitor the system location and posture. The second part is that the driving system equipped with micro-motor and battery so that we can control the carrier to move and use the encoder to record walking distance. The third part is that the detection system is equipped with six Hall sensor and servo motor to achieve cyclic inspection and recording in the tube within 180 °. The defects detected in this experiment were blind hole with 2mm,4mm, 6mm,8mm, depth with 2mm, 4mm,6mm.
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Wen-Wei-Kao and 高文為. "A New Leak Detection System for Pipelines Utilizing Horizontal Porous Tubes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/6uxj4a.
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碩士國立成功大學
資源工程學系
104
This paper presents the results of laboratory tests using an innovative leak-detection system for a long-distance pipeline utilizing soil-gas techniques. Based on the laboratory observations, the effective detection distance of the new system is at least 30 meters and 20 meters for gasoline and diesel, respectively. Because the effective detection radius from the conventional soil-gas probes is only around 5 meters, applying the new detection system to a long-distance pipeline for leak detection minimizes the large number of soil-gas samples and analyses which are required when conventional soil-gas probes are employed.
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Wei-ChenChen and 陳威臣. "A New Leak Detection System for Pipelines Utilizing Horizontal Porous Tubes." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/98484601309651544023.
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碩士國立成功大學
資源工程學系
103
This project presents a new leak detection system for a long-distance pipeline using soil-gas techniques. The new leak detection system runs underground along the nearby pipeline and consists of intermittent porous tubes connected in series with impermeable polyethylene tubes. The effective detection radius from the conventional soil-gas probes is only ~5 m. Applying conventional soil-gas techniques to long-distance pipelines for leak detection usually requires a large number of soil-gas samples and analyses. Laboratory leak tests were conducted using the new system. The effective detection distance of the new system is at least 20 m. Applying the new detection system to long-distance pipelines for leak detection minimizes the large number of soil-gas samples and analyses that are required when conventional soil-gas probes are employed.
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Kang, Hsien-Wen, and 康獻文. "The Novel Configuration Design of the Distributed Fiber Optic Leak Detection System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/54201620220277935820.
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碩士國立中山大學
電機工程學系研究所
89
The technique of the distributed fiber optic sensor system, the principle that we use Sagnac interferometer to sense time-varying physical field, can be used to measure the position of the disturbed physical field and have the ability of detecting continuous position. Based on the configuration of the Sagnac interferometer, sensing optic fiber is loop design, which is hard to be set in real surroundings, and a half length of loop fiber have to be the isolated protection of the physical field. Therefore, this essay brings up the In-Line conception to be the design direction. And we make use of the physical field of pipeline leak acoustic to detect disturbance position. The measurable range of systematic structure signal is 3×10-4 ~ 3×10-2 , and the dynamic range is 40 dB. On the other hand, the structure of polarization insensitive is brought up, the measurable range is 1.5×10-3 ~ 3×10-2 , and the dynamic range is 26 dB.
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Khan, Asar, Peter D. Widdop, Andrew J. Day, Alastair S. Wood, Steve R. Mounce, and James Machell. "Performance assessment of leak detection failure sensors used in a water distribution system." 2005. http://hdl.handle.net/10454/2258.
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KE, SHIUE-SHENG, and 柯學勝. "The Application of the PTP to the Real-time Pipeline Leak Detection System." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/65281572413684912801.
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碩士明志科技大學
電機工程系碩士班
105
Leakage is difficult to detect. It is not only increase the waste of water resources, but also make water resources pollution and even the road collapse, resulting in major public safety accidents. Therefore, the establishment of leak detection system is an urgent task. Taiwan's water company uses rods, leak detectors, and other equipment to detect leaks and thereby find the water leakage point in the small area pipe network. Nevertheless, this method requires narrow the scope again and again until a accumulate the sufficient data for effective detection. This way requires a long time to detect the water leakage point. Given that the above method requires a long time to detect the leakage range, this paper presents a set of Raspberry Pi 3 as the processing core, and established the analysis system in the Linux system in which the measurement equipment combined with accurate time synchronization. By doing so, all sensed data has a the same timestamp, and synchronized with the analysis system to the same time. The same calibration time in the analysis system and can reduce the time-consuming to analyze leaks. The results of the study found that all data in the system had the same exact time, so there is no need to accumulate a large amount of data to be able to analyze, thereby enabling immediate monitoring of the pipeline.
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Su, Jie-Cheng, and 蘇傑誠. "Use of Infrared Gas Leak Detection System for detecting organic from leaking equipment components." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/29244280202216895719.
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碩士崑山科技大學
環境工程研究所
102
In now process of petrochemical industry contains huge pipelines and units. In order to satisfy “Volatile Organic Compound Air Pollution Control and Emission Standards” of Environmental Protection Agency and other relevant laws and regulations, it is unavoidable that units and “VOCs” must to be reduce. Therefore, There it is the demand of “Determination of volatile organic compounds leak－Flame ionisation detector (NIEA A706.73C)” and conventional detections. “Determination of volatile organic compounds leak－Flame Ionisation Detector” adopt common detectors, for example, “Photoionization detector ”and “ Flame ionisation detector ” are most major detectors in detection. In now petrochemical industries, the most common detector to detect is “Portable flame ionization detector”. But this kinds kind of detector is restricted by itself design, it results in limitations of this detection. If only in random sampling, it cannot exactly confirm how leaking situation of every unit is. Some parts of equipments are located at high position and top of tank, situated in high temperature, overcrowd pipelines, and over wet environment. All of them result in limitation of detection and we cannot detect in close distance, or it is affected by other gas of surrounding and we cannot precise to define which unit is leakage. Therefore, the units of sampling tests and self-maintenance in factory are common with blind section, so the quantity of emissions are reported much more lower. In the research, we use “Infrared ray” to scan how leaking situations in different units of industry process is. and work with “Portable flame ionization detector (FID)” in“Flame ionization detection method (NIEA A706.73C)” to detect operations. The research cooperates with 84 factories (147 sessions) process units detections. It was divided into 21,886 process sections, 8,135 storage tank sections, and 5,819 load sections. Leakage rate on units, the loading section (1.27%) was significantly higher than the process section (0.97%) and the storage tank section (0.91%), to explore all types of leakage unit, To study every types of leakage units, and we got the result of that the highest of “Pressure relief valve” for 11.2% , and second is “Pump” for 7.4%, and then are “Opening the valve” for 7.4%, “Valve” for 0.9%, other connecting pipe for 0.8% and “Flange” for 0.6%. Total of 214 leakage detection units are classified into general and difficult detection and to do research. The number of general units are 200, the leakage rate is about 93%; difficult to detect total there are 14, the leakage rate of 7%, compiled 101 year in southern counties 43 sessions process components leakage rate and leak rate comparison over the years, that there are 30 sessions in 101 year screening process units leakage values above over the years of the process leakage rate, the leakage rate of the process with different values of up to 10.5% in difference year. Studies have shown that use of “Eye C Gas” with NIEA A706.73C conventional detection methods, the process can be shortened schedule screening area source of the leak, there are more significant detection rate for spatial location elusive element, helps plant fugitive VOC control.
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Hsieh, Yen-Li, and 謝彥吏. "The Modification Scheme for a Hybrid Mach-Zehnder & Sagnac Interferomtric Fiber Optical Leak Detection System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/09375883795073736027.
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碩士國立中山大學
電機工程學系研究所
89
The reason of the essay research find position of leakage point, and design a fiber optical leakage detection system. The research of fiber optical detection system in past year, because property of structure produce SNR smaller, quality of detection system is too bed. The essay brings to a hybrid Mach-Zehnder & Sagnac interferomtric can improve the SNR to 10dB. Therefore, it provides the better SNR. The experiment is added to signal process, such as PTL, PGC structure. To provide the systematic characteristic, such as dynamic range(60dB), percentage error(0.025%). The focal of the essay provide leak detection systematic characteristics how we make use of signal process.
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BUI, QUANG-NHA, and 裴光雅. "Leak Detection in Water Distribution System based on Bayesian Network Learning and Hybrid Multivariate Regression Particle Swarm Optimization Approach." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/18359183872586142886.
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博士國立臺灣科技大學
營建工程系
104
Leaks in the water distribution systems (WDSs) not only cause waste of resource and energy, but also potential health risk due to polluted water ingress through cracks. Thus, leakage control in the water distribution systems become a compelling but challenging issue in water conservation. This research proposes two models to deal with water leakage problems: The first model called expert structural expectation-maximization (ExSEM) for predicting water leakage in WDSs, and the second one for dealing with leak detection problem by coupling a hybrid multivariate linear regression particle swam optimization (MLR-PSO) with a data-driven optimal sensor placement (DOSP) algorithm. The first model can take into account the uncertainty of leakage-related factors and balance the contribution of monitoring data and prior information in a Bayesian learning process to maximize leakage prediction accuracy, while the combination of two sub-models in the second model help overcome the drawbacks of traditional leak detection methods by significantly reducing the computation time and maintaining robust leak detection capability. The optimal sensor placement strategy bases on exploiting historical data to maximize the leak detectability of the second model. The results of this study could benefit water utilities by aiding them in establishing an effective active leakage control plan to minimize the risk of water leakage. Case studies are presented to demonstrate the robustness and effectiveness of the proposed methods.