This paper introduces leak detection methods that involve the injection of a fluid transient into... more This paper introduces leak detection methods that involve the injection of a fluid transient into the pipeline, with the resultant transient trace analyzed in the frequency domain. Two methods of leak detection using the frequency response of the pipeline are proposed. The inverse resonance method involves matching the modeled frequency responses to those observed to determine the leak parameters. The peak-sequencing method determines the region in which the leak is located by comparing the relative sizes between peaks in the frequency response diagram. It was found that a unique pattern was induced on the peaks of the frequency response for each specific location of the leak within the pipeline. The leak location can be determined by matching the observed pattern to patterns generated numerically within a lookup table. The procedure for extracting the linear frequency response diagram, including the optimum measurement position, the effect of unsteady friction, and the way in which the technique can be extended into pipeline networks, are also discussed within the paper.
1. Am J Nurs. 1975 Mar;75(3):402-6. Drug and diet interactions. Lambert ML Jr. PMID: 234681 [PubM... more 1. Am J Nurs. 1975 Mar;75(3):402-6. Drug and diet interactions. Lambert ML Jr. PMID: 234681 [PubMed - indexed for MEDLINE]. MeSH Terms. Benzothiadiazines; Diet; Diuretics; Drug Therapy/adverse effects*; Food*; Glycyrrhiza; ...
Half a century ago Richard Skalak [see T.C. Skalak, A dedication in memoriam of Dr. Richard Skala... more Half a century ago Richard Skalak [see T.C. Skalak, A dedication in memoriam of Dr. Richard Skalak, Annual Review of Biomedical Engineering 1 (1999) 1-18] published a paper with the title ''An extension of the theory of water hammer'' [R. Skalak, An Extension of the Theory of Water Hammer, PhD Thesis, Faculty of Pure Science, Columbia University, New York, USA, 1954; R. Skalak, An extension of the theory of water hammer, Water Power 7/8 (1955/1956) 458-462/ 17-22; R. Skalak, An extension of the theory of water hammer, Transactions of the ASME 78 (1956) 105-116]
Proceedings of World Environmental and Water Resources Congress 2009 - World Environmental and Water Resources Congress 2009: Great Rivers, 2009
The unpredictable impact of biofilms on friction in pipes causes difficulty in accurately designi... more The unpredictable impact of biofilms on friction in pipes causes difficulty in accurately designing for pipe roughness in biofouled pipes. The effects of biofilm growth on pipe roughness were experimentally investigated with the variation of growth conditions of ...
Chemical beam epitaxy (CBE) is demonstrated here to be a suitable technique for the planarization... more Chemical beam epitaxy (CBE) is demonstrated here to be a suitable technique for the planarization of etched structures by selective overgrowth of InP layers. We present the fabrication of planar buried heterostructure laser diodes (PBH-LDs) with a separate confinement multiquantum well active layer grown by gas source molecular beam epitaxy and p-n InP current blocking layers grown by CBE. These
While artificial neural networks (ANNs) can be extremely valuable tools for water resources model... more While artificial neural networks (ANNs) can be extremely valuable tools for water resources modeling, it is difficult to determine the optimum complexity required to model a given problem. This paper presents a Bayesian model selection (BMS) method for ANNs that provides an objective approach for comparing models of varying complexity in order to select the most appropriate ANN structure. The approach uses MCMC posterior simulations to estimate the evidence in favor of competing models and, in this study, three known methods for doing this are compared in terms of their accuracy and appropriateness for being incorporated into the proposed framework. However, it is acknowledged that evidence approximations based on posterior simulations may be sensitive to factors associated with the MCMC simulation. Therefore, the proposed BMS approach for ANNs incorporates a further check of the evidence results by inspecting the marginal posterior distributions of the hidden-to-output layer weights, which indicate whether all of the hidden nodes in the model are necessary. The fact that this check is available is one of the greatest advantages of the proposed approach over conventional model selection methods, which do not provide such a test and instead rely on the modeler's subjective choice of selection criterion. The proposed BMS approach is demonstrated on two synthetic and one real world water resources case study.
Journal of Water Resources Planning and Management, 2000
... GENETIC ALGORITHMS By John P. Vıtkovský,1 Angus R. Simpson,2 Member, ASCE, and Martin F. Lamb... more ... GENETIC ALGORITHMS By John P. Vıtkovský,1 Angus R. Simpson,2 Member, ASCE, and Martin F. Lambert3 ABSTRACT ... change. Liggett and Chen (1994) proposed the inverse transient method as a calibration and leak detection technique. ...
Journal of Water Resources Planning and Management, 2005
A new blockage detection method using blockage-induced transient damping is developed based on a ... more A new blockage detection method using blockage-induced transient damping is developed based on a linear analytical solution for the transients in a pipeline with a blockage. The linear analysis indicates that pipe friction damping on a pipe transient is exactly exponential, while the blockage damping is exponential for each of the individual harmonic components. For each individual component, the blockage-induced damping depends on the blockage magnitude and position and is independent of measurement location and the transient event. The proposed blockage detection method is successful in detecting, locating and quantifying a pipe blockage based on the laboratory experiments.
Journal of Water Resources Planning and Management, 2003
The quality of leak detection and quantification, and calibration for friction coefficients, in p... more The quality of leak detection and quantification, and calibration for friction coefficients, in pipelines and networks by the inverse transient method are dependent on the quantity and location of data measurement sites. This paper presents an approach for determining the configuration of measurement sites that produces optimal results. Three performance indicators, two that are based on A-and D-optimality criteria and one that is based on the sensitivities of the heads with respect to the parameters, show which configurations are superior. These are illustrated by two case studies, the first of which is a small pipe network in which all configurations are considered directly (fully enumerable) and the second is a larger pipe network in which statistics are drawn from a sampling of configurations. For the large network, a genetic algorithm-with a new crossover operator-performs a search of
This paper presents a method of leak detection in a single pipe where the behaviour of the system... more This paper presents a method of leak detection in a single pipe where the behaviour of the system frequency response diagram (FRD) is used as an indicator of the pipe integrity. The presence of a leak in a pipe imposes a pattern on the resonance peaks of the FRD that can be used as a clear indication of leakage. Analytical expressions describing the pattern of the resonance peaks are derived. Illustrations of how this pattern can be used to individually locate and size multiple leaks within the system are presented. Practical issues with the technique, such as the procedure for frequency response extraction, the impact of measurement position, noise-and frequency-dependent friction are also discussed. r
The extreme value distributions of hydrologic variables such as rainfall and streamflow play a ke... more The extreme value distributions of hydrologic variables such as rainfall and streamflow play a key role in the design of water related infrastructure. The relationship between the intensity, frequency and duration of extreme values is commonly evaluated using observed annual maximum values. This paper considers maximum values that occur within a given season and the relationship between seasonal maxima and annual maxima. Using a climatic index, the seasonal and annual maxima are also partitioned into multiple climatic states so that comparisons of seasonal maxima both within and between climatic states can be made. The distributions of seasonal and annual rainfall maxima are investigated for numerous locations around Australia and a detailed analysis, involving both seasonal and climatic partitions, is given for the daily streamflows of the Murray-Darling Basin, Australia. The results demonstrate significant differences between seasonal distributions within and between climatic states. The application of seasonal extremes to an urban design scenario is illustrated for Scott Creek in the Adelaide Hills, South Australia. The methodology presented can be used in a general setting to gain insight into the relationship between extremes from seasonal and climatic periods to their annual counterparts.
The point rainfall model presented extends previous work on event-based rainfall models and overc... more The point rainfall model presented extends previous work on event-based rainfall models and overcomes some of their shortcomings. The model uses event-based data and can be calibrated using rainfall data substantially affected by missing or corrupted values. Particular attention was given to adequately simulating extreme storm rainfall events for use in hydrological risk assessment. The model is capable of simulating
This paper presents an experimental validation of the frequency response method for pipeline leak... more This paper presents an experimental validation of the frequency response method for pipeline leak detection. The presence of a leak within the pipe imposes a periodic pattern on the resonant peaks of the frequency response diagram. This pattern can be used as an indicator of leaks without requiring the "no-leak" benchmark for comparison. In addition to the experimental verification of the technique, important issues, such as the procedure for frequency response extraction and methods for dealing with frequency-dependent friction are considered in this paper. In this study, transient signals are generated by a side-discharge solenoid valve. Non-linearity errors associated with large valve movements can be prevented by a change in the input parameter to the system. The optimum measuring and generating position for two different system boundary configurations-a symmetric and an antisymmetric system-are discussed in the paper and the analytical expression for the leak-induced pattern in these two cases is derived.
Full-scale field acoustic Doppler velocimeter measurements of the radial, axial, and tangential f... more Full-scale field acoustic Doppler velocimeter measurements of the radial, axial, and tangential flow components were undertaken in a large-diameter turbulent swirling jet generated by a raft-mounted axial flow-mixing propeller discharging through a draft tube ...
This paper proposes the use of fluid transients as a noninvasive technique for locating blockages... more This paper proposes the use of fluid transients as a noninvasive technique for locating blockages in transmission pipelines. By extracting the behavior of the system in the form of a frequency response diagram, discrete blockages within the pipeline were shown to induce an oscillatory pattern on the peaks of this response diagram. This pattern can be related to the location and size of the blockage. A simple analytical expression that can be used to detect, locate, and size discrete blockages is presented, and is shown able to cater for multiple blockages existing simultaneously within the system. The structure of the expression suggests that the proposed technique can be extended to situations where system parameters may not be known to a high accuracy and also to more complex network scenarios, although future studies may be required to verify these possibilities.
Hydraulic transient field tests have been conducted in a water distribution network. Existing tra... more Hydraulic transient field tests have been conducted in a water distribution network. Existing transient models are applied to model the measured responses, but poor matches are obtained apart from the estimation of the initial rise of pressure. Possible reasons for these discrepancies include the effects of demands, entrained air, unsteady friction, friction losses associated with small lateral pipes, and mechanical damping caused by the interaction of pipes and joints with surrounding soils (including the effects of vibration and different degrees of restraint). These effects are systematically investigated by inclusion of the previously mentioned phenomena in conceptual transient models and calibration to the measured field responses. A mechanical damping-based conceptual transient model is shown to be the only model that can be accurately calibrated to the measured field responses.
Leaks in pipelines contribute to damping of transient events. That fact leads to a method to find... more Leaks in pipelines contribute to damping of transient events. That fact leads to a method to find location and magnitude of leaks. Because the problem of transient flow in pipes is nearly linear, the solution of the governing equations can be expressed in terms of a Fourier series. All Fourier components are damped uniformly by steady pipe friction, but each component is damped differently in the presence of a leak. Thus, overall leakinduced damping can be divided into two parts. The magnitude of the damping indicates size of a leak whereas different damping ratios of the various Fourier components are used to find location of a leak. This method does not require rigorous determination and modeling of boundary conditions and transient behavior in the pipeline. The technique is successful in detecting, locating and quantifying a 0.1% size leak with respect to the crosssectional area of a pipeline.
This paper introduces leak detection methods that involve the injection of a fluid transient into... more This paper introduces leak detection methods that involve the injection of a fluid transient into the pipeline, with the resultant transient trace analyzed in the frequency domain. Two methods of leak detection using the frequency response of the pipeline are proposed. The inverse resonance method involves matching the modeled frequency responses to those observed to determine the leak parameters. The peak-sequencing method determines the region in which the leak is located by comparing the relative sizes between peaks in the frequency response diagram. It was found that a unique pattern was induced on the peaks of the frequency response for each specific location of the leak within the pipeline. The leak location can be determined by matching the observed pattern to patterns generated numerically within a lookup table. The procedure for extracting the linear frequency response diagram, including the optimum measurement position, the effect of unsteady friction, and the way in which the technique can be extended into pipeline networks, are also discussed within the paper.
1. Am J Nurs. 1975 Mar;75(3):402-6. Drug and diet interactions. Lambert ML Jr. PMID: 234681 [PubM... more 1. Am J Nurs. 1975 Mar;75(3):402-6. Drug and diet interactions. Lambert ML Jr. PMID: 234681 [PubMed - indexed for MEDLINE]. MeSH Terms. Benzothiadiazines; Diet; Diuretics; Drug Therapy/adverse effects*; Food*; Glycyrrhiza; ...
Half a century ago Richard Skalak [see T.C. Skalak, A dedication in memoriam of Dr. Richard Skala... more Half a century ago Richard Skalak [see T.C. Skalak, A dedication in memoriam of Dr. Richard Skalak, Annual Review of Biomedical Engineering 1 (1999) 1-18] published a paper with the title ''An extension of the theory of water hammer'' [R. Skalak, An Extension of the Theory of Water Hammer, PhD Thesis, Faculty of Pure Science, Columbia University, New York, USA, 1954; R. Skalak, An extension of the theory of water hammer, Water Power 7/8 (1955/1956) 458-462/ 17-22; R. Skalak, An extension of the theory of water hammer, Transactions of the ASME 78 (1956) 105-116]
Proceedings of World Environmental and Water Resources Congress 2009 - World Environmental and Water Resources Congress 2009: Great Rivers, 2009
The unpredictable impact of biofilms on friction in pipes causes difficulty in accurately designi... more The unpredictable impact of biofilms on friction in pipes causes difficulty in accurately designing for pipe roughness in biofouled pipes. The effects of biofilm growth on pipe roughness were experimentally investigated with the variation of growth conditions of ...
Chemical beam epitaxy (CBE) is demonstrated here to be a suitable technique for the planarization... more Chemical beam epitaxy (CBE) is demonstrated here to be a suitable technique for the planarization of etched structures by selective overgrowth of InP layers. We present the fabrication of planar buried heterostructure laser diodes (PBH-LDs) with a separate confinement multiquantum well active layer grown by gas source molecular beam epitaxy and p-n InP current blocking layers grown by CBE. These
While artificial neural networks (ANNs) can be extremely valuable tools for water resources model... more While artificial neural networks (ANNs) can be extremely valuable tools for water resources modeling, it is difficult to determine the optimum complexity required to model a given problem. This paper presents a Bayesian model selection (BMS) method for ANNs that provides an objective approach for comparing models of varying complexity in order to select the most appropriate ANN structure. The approach uses MCMC posterior simulations to estimate the evidence in favor of competing models and, in this study, three known methods for doing this are compared in terms of their accuracy and appropriateness for being incorporated into the proposed framework. However, it is acknowledged that evidence approximations based on posterior simulations may be sensitive to factors associated with the MCMC simulation. Therefore, the proposed BMS approach for ANNs incorporates a further check of the evidence results by inspecting the marginal posterior distributions of the hidden-to-output layer weights, which indicate whether all of the hidden nodes in the model are necessary. The fact that this check is available is one of the greatest advantages of the proposed approach over conventional model selection methods, which do not provide such a test and instead rely on the modeler's subjective choice of selection criterion. The proposed BMS approach is demonstrated on two synthetic and one real world water resources case study.
Journal of Water Resources Planning and Management, 2000
... GENETIC ALGORITHMS By John P. Vıtkovský,1 Angus R. Simpson,2 Member, ASCE, and Martin F. Lamb... more ... GENETIC ALGORITHMS By John P. Vıtkovský,1 Angus R. Simpson,2 Member, ASCE, and Martin F. Lambert3 ABSTRACT ... change. Liggett and Chen (1994) proposed the inverse transient method as a calibration and leak detection technique. ...
Journal of Water Resources Planning and Management, 2005
A new blockage detection method using blockage-induced transient damping is developed based on a ... more A new blockage detection method using blockage-induced transient damping is developed based on a linear analytical solution for the transients in a pipeline with a blockage. The linear analysis indicates that pipe friction damping on a pipe transient is exactly exponential, while the blockage damping is exponential for each of the individual harmonic components. For each individual component, the blockage-induced damping depends on the blockage magnitude and position and is independent of measurement location and the transient event. The proposed blockage detection method is successful in detecting, locating and quantifying a pipe blockage based on the laboratory experiments.
Journal of Water Resources Planning and Management, 2003
The quality of leak detection and quantification, and calibration for friction coefficients, in p... more The quality of leak detection and quantification, and calibration for friction coefficients, in pipelines and networks by the inverse transient method are dependent on the quantity and location of data measurement sites. This paper presents an approach for determining the configuration of measurement sites that produces optimal results. Three performance indicators, two that are based on A-and D-optimality criteria and one that is based on the sensitivities of the heads with respect to the parameters, show which configurations are superior. These are illustrated by two case studies, the first of which is a small pipe network in which all configurations are considered directly (fully enumerable) and the second is a larger pipe network in which statistics are drawn from a sampling of configurations. For the large network, a genetic algorithm-with a new crossover operator-performs a search of
This paper presents a method of leak detection in a single pipe where the behaviour of the system... more This paper presents a method of leak detection in a single pipe where the behaviour of the system frequency response diagram (FRD) is used as an indicator of the pipe integrity. The presence of a leak in a pipe imposes a pattern on the resonance peaks of the FRD that can be used as a clear indication of leakage. Analytical expressions describing the pattern of the resonance peaks are derived. Illustrations of how this pattern can be used to individually locate and size multiple leaks within the system are presented. Practical issues with the technique, such as the procedure for frequency response extraction, the impact of measurement position, noise-and frequency-dependent friction are also discussed. r
The extreme value distributions of hydrologic variables such as rainfall and streamflow play a ke... more The extreme value distributions of hydrologic variables such as rainfall and streamflow play a key role in the design of water related infrastructure. The relationship between the intensity, frequency and duration of extreme values is commonly evaluated using observed annual maximum values. This paper considers maximum values that occur within a given season and the relationship between seasonal maxima and annual maxima. Using a climatic index, the seasonal and annual maxima are also partitioned into multiple climatic states so that comparisons of seasonal maxima both within and between climatic states can be made. The distributions of seasonal and annual rainfall maxima are investigated for numerous locations around Australia and a detailed analysis, involving both seasonal and climatic partitions, is given for the daily streamflows of the Murray-Darling Basin, Australia. The results demonstrate significant differences between seasonal distributions within and between climatic states. The application of seasonal extremes to an urban design scenario is illustrated for Scott Creek in the Adelaide Hills, South Australia. The methodology presented can be used in a general setting to gain insight into the relationship between extremes from seasonal and climatic periods to their annual counterparts.
The point rainfall model presented extends previous work on event-based rainfall models and overc... more The point rainfall model presented extends previous work on event-based rainfall models and overcomes some of their shortcomings. The model uses event-based data and can be calibrated using rainfall data substantially affected by missing or corrupted values. Particular attention was given to adequately simulating extreme storm rainfall events for use in hydrological risk assessment. The model is capable of simulating
This paper presents an experimental validation of the frequency response method for pipeline leak... more This paper presents an experimental validation of the frequency response method for pipeline leak detection. The presence of a leak within the pipe imposes a periodic pattern on the resonant peaks of the frequency response diagram. This pattern can be used as an indicator of leaks without requiring the "no-leak" benchmark for comparison. In addition to the experimental verification of the technique, important issues, such as the procedure for frequency response extraction and methods for dealing with frequency-dependent friction are considered in this paper. In this study, transient signals are generated by a side-discharge solenoid valve. Non-linearity errors associated with large valve movements can be prevented by a change in the input parameter to the system. The optimum measuring and generating position for two different system boundary configurations-a symmetric and an antisymmetric system-are discussed in the paper and the analytical expression for the leak-induced pattern in these two cases is derived.
Full-scale field acoustic Doppler velocimeter measurements of the radial, axial, and tangential f... more Full-scale field acoustic Doppler velocimeter measurements of the radial, axial, and tangential flow components were undertaken in a large-diameter turbulent swirling jet generated by a raft-mounted axial flow-mixing propeller discharging through a draft tube ...
This paper proposes the use of fluid transients as a noninvasive technique for locating blockages... more This paper proposes the use of fluid transients as a noninvasive technique for locating blockages in transmission pipelines. By extracting the behavior of the system in the form of a frequency response diagram, discrete blockages within the pipeline were shown to induce an oscillatory pattern on the peaks of this response diagram. This pattern can be related to the location and size of the blockage. A simple analytical expression that can be used to detect, locate, and size discrete blockages is presented, and is shown able to cater for multiple blockages existing simultaneously within the system. The structure of the expression suggests that the proposed technique can be extended to situations where system parameters may not be known to a high accuracy and also to more complex network scenarios, although future studies may be required to verify these possibilities.
Hydraulic transient field tests have been conducted in a water distribution network. Existing tra... more Hydraulic transient field tests have been conducted in a water distribution network. Existing transient models are applied to model the measured responses, but poor matches are obtained apart from the estimation of the initial rise of pressure. Possible reasons for these discrepancies include the effects of demands, entrained air, unsteady friction, friction losses associated with small lateral pipes, and mechanical damping caused by the interaction of pipes and joints with surrounding soils (including the effects of vibration and different degrees of restraint). These effects are systematically investigated by inclusion of the previously mentioned phenomena in conceptual transient models and calibration to the measured field responses. A mechanical damping-based conceptual transient model is shown to be the only model that can be accurately calibrated to the measured field responses.
Leaks in pipelines contribute to damping of transient events. That fact leads to a method to find... more Leaks in pipelines contribute to damping of transient events. That fact leads to a method to find location and magnitude of leaks. Because the problem of transient flow in pipes is nearly linear, the solution of the governing equations can be expressed in terms of a Fourier series. All Fourier components are damped uniformly by steady pipe friction, but each component is damped differently in the presence of a leak. Thus, overall leakinduced damping can be divided into two parts. The magnitude of the damping indicates size of a leak whereas different damping ratios of the various Fourier components are used to find location of a leak. This method does not require rigorous determination and modeling of boundary conditions and transient behavior in the pipeline. The technique is successful in detecting, locating and quantifying a 0.1% size leak with respect to the crosssectional area of a pipeline.
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Papers by Martin LAMBERT