Abstract: In certain rivers that drain very flat terrains in coastal areas, the streamflow series... more Abstract: In certain rivers that drain very flat terrains in coastal areas, the streamflow series observed at a flow-gauging station may come under the direct influence of the backwater effects of tides. The phenomena may be negligible under conditions of high flows but can be critical under some extreme low-flow conditions. The errors in low flow estimation are large if a proper de-noising is not implemented to remove the effects of the tidal effects. Scrutinizing the hydrologic time series using a standard time-frequency do-main based Fourier transform methodology cannot resolve conclusively the sources of the noise. However, a new perspective can be obtained by using a wavelet transformation to analyze the time series in the time-scale domain. By using this approach, a case study involving a streamflow series observed at Kapit, Sarawak, Malaysia yielded conclusive evidence of the influence of tides at the flow-gauging site during the low flow period. Upon confirma-tion that the n...
This paper investigated the incorporation of waste Polyethylene Terephthalate (PET) from plastic ... more This paper investigated the incorporation of waste Polyethylene Terephthalate (PET) from plastic bottles into concrete as a replacement for natural fine aggregate and found an optimal combination of components that produces a useful concrete product. Six components were considered: cement, water, coarse aggregate, fine aggregate, superplasticizer, and waste PET. A total of 31 mixes including waste PET were prepared based on a statistical mixture design approach. The responses of these mixtures were workability, compressive strength, and splitting tensile strength. The waste PET was first reduced in volume by shredding and then combined with the rest of the components. The responses from the experiments were statistically analysed and a model fitted to each response. Linear models were found to fit the responses best. Using the desirability function approach, four optimal options were selected and then verified in the lab by comparing the experimental with the predicted values. Excep...
Canadian Journal of Civil Engineering, Jun 1, 1986
The well-established occurrence of exceptionally high floods on the Red River prior to the record... more The well-established occurrence of exceptionally high floods on the Red River prior to the record of annual peak flows at Winnipeg is an important factor in the flood risk assessment for that city and for the entire Red River valley. But the weight given to this occurrence is quite dependent on the autocorrelation structure assumed for the spring peak time series. It is therefore important to decide whether the clustering of high peak flows, which can be observed in the record, is a mere chance phenomenon or indeed a characteristic of the runoff process. In earlier studies this clustering was found to be significant in a statistical sense. The present study aims at finding a physical explanation for this particular type of correlation structure. It presents the accumulated basin storage (ABS) as a physically based parameter that measures average soil moisture conditions in the drainage basin. The reconstructed record of ABS values just prior to the spring runoff shows a very high first-order autocorrelation coefficient. Relatively wet and relatively dry soil conditions therefore tend to persist over long periods. Since the magnitude of the spring peak is significantly affected by soil moisture conditions prior to snowmelt, the structure of the annual ABS time series can be expected to be reflected in the peak flow time series. This was found to be the case. The study thus supports earlier conclusions based on statistical evidence that the conventional assumption of serially independent spring peak floods seriously underestimates the flood risk for the City of Winnipeg and the Red River valley. Key words: accumulated basin storage, Red River floods, simulation, time series, clustering, streamflow persistence, serial correlation, flood risk.
Oil spills in the Arctic have drawn dramatic attention in recent years. Frazil ice, as the essent... more Oil spills in the Arctic have drawn dramatic attention in recent years. Frazil ice, as the essential formation of sea ice, may affect the effectiveness of dispersants during oil spill response and the associated behaviors of dispersed oil. However, these impacts remain poorly understood, limiting the appropriate usage of dispersants in ice-covered regions. Herein this work explored the effects of frazil ice on the dispersion effectiveness of two dispersants (Corexit 9500A and hydrolyzed shrimp waste) and the migration of dispersed oil within frazil ice. We discovered that frazil ice inhibited dispersion effectiveness by attenuating water velocity. Permeable frazil ice encapsulated 11-30% of dispersed oil, implying a lower oil bioavailability. We thus proposed and verified a microscopic mechanism to unravel the migration of dispersed oil toward permeable constrictions in frazil ice. We predicted the concentration of dispersed oil encapsulated in frazil ice using bed filtration theory and verified the prediction through experiments. Furthermore, the presence of frazil ice can lead to the breakup and coalescence of dispersed oil. Overall, our findings would facilitate the appropriate planning and decision-making of dispersant-based oil spill response and a better understanding of the fate of dispersed oil in the frazil ice-infested ocean.
Abstract: In this paper, a combined use of dimensional analysis (DA) and statistical design of ex... more Abstract: In this paper, a combined use of dimensional analysis (DA) and statistical design of experiments (DOE) is proposed for a hydrodynamics experiment where there are a large number of variables. While DA is well-known, DOE is still unfamiliar to most ocean engineers although it has been shown to be extremely useful in many engineering applications. To illustrate the method, a study concerning the thrust of a podded propeller is considered. Fifteen variables are involved in the problem and after dimensional analysis this reduces to 12 dimensionless parameters. Then, a two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent dimensionless parameter. With the remaining five statistically significant dimensional parameters, response surface methodology (RSM) was used to obtain a functional relationship between the dependent dimensionless thrust coefficient, and the five dimensionless parameters. The model was found to be of reasonable accuracy. The methodology presented in the paper can be applied to any system with a large number of control variables to derive an approximate mathematical model to predict the response of the system economically and accurately.
AbstractUnderstanding the persistence in land surface processes, such as that in the deep subsurf... more AbstractUnderstanding the persistence in land surface processes, such as that in the deep subsurface moisture storage, has great implications for seasonal weather prediction over a drainage basin. The Canadian Prairies is a region of intense and recurrent drought outbreaks with myriad negative impacts on the regional ecosystem as well as on all sectors of the Prairies’ economy due to high mitigation costs associated with these frequent outbreaks. Given that there are neither physical observations of soil moisture at depths of hydrological importance nor measurements of the total water storage over drought-prone Canadian Prairies subcatchments, this places constraints on studies that focus on the assessments of the interrelationship between the land surface and atmospheric processes. This study focuses on the estimation of the memory in the simulated deep soil moisture and total water storages over the 406,000 km2 Saskatchewan River Basin (SRB) in the Canadian Prairies using a physically based land surfac...
Graduate engineering programs at Memorial University's Faculty of Engineering and Applied Sci... more Graduate engineering programs at Memorial University's Faculty of Engineering and Applied Science are not accredited and as such there is no information available on non-technical professional skills development. These skills are essential for successful entry into the Canadian engineering community. To assess the current graduate program, an assessment methodology was developed based on the CEAB graduate attribute assessment process used for undergraduate program accreditation. An initial application of this methodology to Process Engineering indicates that all professional skills are not covered for all students. This lead to modifications for current programing that will ensure all students are exposed to the skills needed for a successful career in engineering.
Understanding the memory in land surface processes, such as that in the subsurface moisture stora... more Understanding the memory in land surface processes, such as that in the subsurface moisture storage has great implication for seasonal weather prediction over a catchment. The Canadian Prairies is a region of intense and recurrent drought outbreaks with myriad negative impacts on all sectors of the economy due to the associated high mitigation costs. However, given that there are no physical observations of soil moisture at depths of hydrological importance or measurements of the total water storage, it is infeasible to undertake studies on land-atmosphere interactions. This study is focused on estimating the memory in the simulated deep soil moisture and total water storages over the 406,000 km2 Saskatchewan River Basin (SRB) in the Canadian Prairies using a physically-based land surface model. Using relevant statistical techniques, it is possible to quantify the persistency in the anomalies of the meteorological variables, modeled moisture storage components as well as the memory ...
Graduate student teaching assistant (TA) training is a one-day intensive program at Memorial Univ... more Graduate student teaching assistant (TA) training is a one-day intensive program at Memorial University's Faculty of Engineering and Applied Science that introduces new graduate students to the roles and responsibilities of being an effective TA. This program uses online tools, case studies and theory discussions to orient new TA's to teaching and learning practices. A recent survey of graduate students taken after completion of the TA training led to modification of the current program. This paper will outline the program, proposed changes to the program and demonstrate how adapting student feedback can contribute to continuous improvements in student education.
Abstract: In certain rivers that drain very flat terrains in coastal areas, the streamflow series... more Abstract: In certain rivers that drain very flat terrains in coastal areas, the streamflow series observed at a flow-gauging station may come under the direct influence of the backwater effects of tides. The phenomena may be negligible under conditions of high flows but can be critical under some extreme low-flow conditions. The errors in low flow estimation are large if a proper de-noising is not implemented to remove the effects of the tidal effects. Scrutinizing the hydrologic time series using a standard time-frequency do-main based Fourier transform methodology cannot resolve conclusively the sources of the noise. However, a new perspective can be obtained by using a wavelet transformation to analyze the time series in the time-scale domain. By using this approach, a case study involving a streamflow series observed at Kapit, Sarawak, Malaysia yielded conclusive evidence of the influence of tides at the flow-gauging site during the low flow period. Upon confirma-tion that the n...
This paper investigated the incorporation of waste Polyethylene Terephthalate (PET) from plastic ... more This paper investigated the incorporation of waste Polyethylene Terephthalate (PET) from plastic bottles into concrete as a replacement for natural fine aggregate and found an optimal combination of components that produces a useful concrete product. Six components were considered: cement, water, coarse aggregate, fine aggregate, superplasticizer, and waste PET. A total of 31 mixes including waste PET were prepared based on a statistical mixture design approach. The responses of these mixtures were workability, compressive strength, and splitting tensile strength. The waste PET was first reduced in volume by shredding and then combined with the rest of the components. The responses from the experiments were statistically analysed and a model fitted to each response. Linear models were found to fit the responses best. Using the desirability function approach, four optimal options were selected and then verified in the lab by comparing the experimental with the predicted values. Excep...
Canadian Journal of Civil Engineering, Jun 1, 1986
The well-established occurrence of exceptionally high floods on the Red River prior to the record... more The well-established occurrence of exceptionally high floods on the Red River prior to the record of annual peak flows at Winnipeg is an important factor in the flood risk assessment for that city and for the entire Red River valley. But the weight given to this occurrence is quite dependent on the autocorrelation structure assumed for the spring peak time series. It is therefore important to decide whether the clustering of high peak flows, which can be observed in the record, is a mere chance phenomenon or indeed a characteristic of the runoff process. In earlier studies this clustering was found to be significant in a statistical sense. The present study aims at finding a physical explanation for this particular type of correlation structure. It presents the accumulated basin storage (ABS) as a physically based parameter that measures average soil moisture conditions in the drainage basin. The reconstructed record of ABS values just prior to the spring runoff shows a very high first-order autocorrelation coefficient. Relatively wet and relatively dry soil conditions therefore tend to persist over long periods. Since the magnitude of the spring peak is significantly affected by soil moisture conditions prior to snowmelt, the structure of the annual ABS time series can be expected to be reflected in the peak flow time series. This was found to be the case. The study thus supports earlier conclusions based on statistical evidence that the conventional assumption of serially independent spring peak floods seriously underestimates the flood risk for the City of Winnipeg and the Red River valley. Key words: accumulated basin storage, Red River floods, simulation, time series, clustering, streamflow persistence, serial correlation, flood risk.
Oil spills in the Arctic have drawn dramatic attention in recent years. Frazil ice, as the essent... more Oil spills in the Arctic have drawn dramatic attention in recent years. Frazil ice, as the essential formation of sea ice, may affect the effectiveness of dispersants during oil spill response and the associated behaviors of dispersed oil. However, these impacts remain poorly understood, limiting the appropriate usage of dispersants in ice-covered regions. Herein this work explored the effects of frazil ice on the dispersion effectiveness of two dispersants (Corexit 9500A and hydrolyzed shrimp waste) and the migration of dispersed oil within frazil ice. We discovered that frazil ice inhibited dispersion effectiveness by attenuating water velocity. Permeable frazil ice encapsulated 11-30% of dispersed oil, implying a lower oil bioavailability. We thus proposed and verified a microscopic mechanism to unravel the migration of dispersed oil toward permeable constrictions in frazil ice. We predicted the concentration of dispersed oil encapsulated in frazil ice using bed filtration theory and verified the prediction through experiments. Furthermore, the presence of frazil ice can lead to the breakup and coalescence of dispersed oil. Overall, our findings would facilitate the appropriate planning and decision-making of dispersant-based oil spill response and a better understanding of the fate of dispersed oil in the frazil ice-infested ocean.
Abstract: In this paper, a combined use of dimensional analysis (DA) and statistical design of ex... more Abstract: In this paper, a combined use of dimensional analysis (DA) and statistical design of experiments (DOE) is proposed for a hydrodynamics experiment where there are a large number of variables. While DA is well-known, DOE is still unfamiliar to most ocean engineers although it has been shown to be extremely useful in many engineering applications. To illustrate the method, a study concerning the thrust of a podded propeller is considered. Fifteen variables are involved in the problem and after dimensional analysis this reduces to 12 dimensionless parameters. Then, a two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent dimensionless parameter. With the remaining five statistically significant dimensional parameters, response surface methodology (RSM) was used to obtain a functional relationship between the dependent dimensionless thrust coefficient, and the five dimensionless parameters. The model was found to be of reasonable accuracy. The methodology presented in the paper can be applied to any system with a large number of control variables to derive an approximate mathematical model to predict the response of the system economically and accurately.
AbstractUnderstanding the persistence in land surface processes, such as that in the deep subsurf... more AbstractUnderstanding the persistence in land surface processes, such as that in the deep subsurface moisture storage, has great implications for seasonal weather prediction over a drainage basin. The Canadian Prairies is a region of intense and recurrent drought outbreaks with myriad negative impacts on the regional ecosystem as well as on all sectors of the Prairies’ economy due to high mitigation costs associated with these frequent outbreaks. Given that there are neither physical observations of soil moisture at depths of hydrological importance nor measurements of the total water storage over drought-prone Canadian Prairies subcatchments, this places constraints on studies that focus on the assessments of the interrelationship between the land surface and atmospheric processes. This study focuses on the estimation of the memory in the simulated deep soil moisture and total water storages over the 406,000 km2 Saskatchewan River Basin (SRB) in the Canadian Prairies using a physically based land surfac...
Graduate engineering programs at Memorial University's Faculty of Engineering and Applied Sci... more Graduate engineering programs at Memorial University's Faculty of Engineering and Applied Science are not accredited and as such there is no information available on non-technical professional skills development. These skills are essential for successful entry into the Canadian engineering community. To assess the current graduate program, an assessment methodology was developed based on the CEAB graduate attribute assessment process used for undergraduate program accreditation. An initial application of this methodology to Process Engineering indicates that all professional skills are not covered for all students. This lead to modifications for current programing that will ensure all students are exposed to the skills needed for a successful career in engineering.
Understanding the memory in land surface processes, such as that in the subsurface moisture stora... more Understanding the memory in land surface processes, such as that in the subsurface moisture storage has great implication for seasonal weather prediction over a catchment. The Canadian Prairies is a region of intense and recurrent drought outbreaks with myriad negative impacts on all sectors of the economy due to the associated high mitigation costs. However, given that there are no physical observations of soil moisture at depths of hydrological importance or measurements of the total water storage, it is infeasible to undertake studies on land-atmosphere interactions. This study is focused on estimating the memory in the simulated deep soil moisture and total water storages over the 406,000 km2 Saskatchewan River Basin (SRB) in the Canadian Prairies using a physically-based land surface model. Using relevant statistical techniques, it is possible to quantify the persistency in the anomalies of the meteorological variables, modeled moisture storage components as well as the memory ...
Graduate student teaching assistant (TA) training is a one-day intensive program at Memorial Univ... more Graduate student teaching assistant (TA) training is a one-day intensive program at Memorial University's Faculty of Engineering and Applied Science that introduces new graduate students to the roles and responsibilities of being an effective TA. This program uses online tools, case studies and theory discussions to orient new TA's to teaching and learning practices. A recent survey of graduate students taken after completion of the TA training led to modification of the current program. This paper will outline the program, proposed changes to the program and demonstrate how adapting student feedback can contribute to continuous improvements in student education.
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Papers by Leonard Lye