L. Duguay - Academia.edu (original) (raw)
Papers by L. Duguay
Canadian Journal of Public Health, 2002
The interactions between humans and the ocean are significant, and necessitate more comprehensive... more The interactions between humans and the ocean are significant, and necessitate more comprehensive study on an international scale. The world's oceans provide great health benefits to humans ranging from food and nutritional resources, to recreational opportunities and new treatments for human disease. However, recently, human health effects from exposure to substances present in the marine ecosystem such as synthetic organic chemicals (e.g., chlorobiphenyls, chlorinated dioxins and some industrial solvents), polycyclic aromatic hydrocarbons (PAHs), metals (both introduced and anthropogenic), marine toxins, and pathogens have been recorded and are of great concern. This paper reviews our state of knowledge of the interactions between oceans and human health and proposes indicators and a research strategy to investigate and monitor these relationships more closely. Four approaches to gathering information on indicators included here are: biomarkers; cellular pathology; physiological and behavioural responses; and changes in populations. All hold the potential to enhance our understanding of marine environmental quality and far-reaching effects on human health. Monitoring systems that include the rapid assessment of contaminants in the ecosystem and subsequent risk to human populations, with appropriate internationally distributed data bases, need to be developed and validated. Such tools would provide early detection of potential environmental threats, and enhance the ability to prevent human illness.
The Journal of Foraminiferal Research, 1983
... Light-en-hanced calcification in corals has been shown to be intimately linked with the photo... more ... Light-en-hanced calcification in corals has been shown to be intimately linked with the photosynthetic activity of the associated ... of laboratory experiments that clearly demonstrated the dependence of light-enhanced cal-cium uptake by the foraminifera, Archnias angularus. ...
Site characterization and biofouling studies were conducted at a site about seven miles north of ... more Site characterization and biofouling studies were conducted at a site about seven miles north of St. Croix, U.S. Virgin Islands, during July to September, 1977. The devices basically consisted of aluminum pipes (8' long x 1'' ID) through which seawater flowed at rates of 3 or 6 ft sec/sup -1/. The units were mounted on the deck of a barge, moored in water of depth about 4000 m, and seawater for the experiment was obtained from a depth of about 20 m ATP and carbon and nitrogen contents, microbial plate counts (bacteria, yeasts, filamentous fungi) were employed as measures of biofouling films within the aluminum pipes. Chlorophyll a and phaeo-pigment determinations indicated that viable and dead photosynthetic microbes were insignificant in the fouling films. No major differences in biofouling were observed between the two seawater flow rates, either in the CMU or RSMAS pipes. The general conclusion from the site characterization work is that the nutrient and microbial loa...
Applied and environmental microbiology, 1993
The Fe protein of nitrogenase in the marine nonheterocystous cyanobacterium Trichodesmium thiebau... more The Fe protein of nitrogenase in the marine nonheterocystous cyanobacterium Trichodesmium thiebautii is interconverted between two forms, which is reminiscent of the ADP-ribosylation described in the purple bacterium Rhodospirillum rubrum. In natural populations of T. thiebautii during the day, when nitrogenase activity (NA) is present and while photosynthetic rates are high, a low-molecular-mass form of the Fe protein is present. In the late afternoon, the low-molecular-mass form is partially converted to a higher-molecular-mass form (approximately equal distribution of high- and low-molecular-mass forms of the Fe protein subunits), concurrent with cessation of NA. Some of the higher-molecular-mass form persists through the night until the very early morning, when the lower-molecular-mass form appears. New synthesis of both the Fe and MoFe proteins of nitrogenase appears to occur at this time. The higher-molecular-mass form of the Fe protein is also produced rapidly in response to ...
ICECS 2000. 7th IEEE International Conference on Electronics, Circuits and Systems (Cat. No.00EX445), 2000
This paper presents a PWM-based control system associated with a single-phase two-stage boost rec... more This paper presents a PWM-based control system associated with a single-phase two-stage boost rectifier. Linear regulators are designed on the basis of a frequency-domain dynamical model of the converter. The input impedance and the dynamical susceptibility of the controlled system are then computed and analysed
2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230), 2001
A new nonlinear control technique applied to a current-injection three-phase rectifier (CITPR) is... more A new nonlinear control technique applied to a current-injection three-phase rectifier (CITPR) is proposed. Based on a nonlinear low-frequency mathematical model of the converter, the design procedure of the proposed control technique is divided into two steps. Firstly, two internal feedback loops for current shaping are elaborated on the basis of an input-output system linearization method. Secondly, in order to ensure the regulation of the output voltage, an external loop is then designed taking into account the inner current loops. The control strategy is evaluated by simulation using Matlab/Simulink toolbox. The numerical results obtained show the superiority of the new control technique in comparison to the linear one
2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230), 2001
In this paper, a new mathematical nonlinear model of a three-phase rectifier with current injecti... more In this paper, a new mathematical nonlinear model of a three-phase rectifier with current injection network is elaborated. The approach adopted is based on the state-space-averaging method A small-signal approximate linear dynamic model is then generated in the frequency domain. The model is validated using harmonic identification technique. Simulation results, using the Power System Blockset tool, are compared to the
INTELEC. Twenty-Second International Telecommunications Energy Conference (Cat. No.00CH37131), 2000
In this paper, a new control strategy based on the pulse-width-modulation (PWM) control technique... more In this paper, a new control strategy based on the pulse-width-modulation (PWM) control technique and using a single feedback current loop is proposed. The control scheme is applied to a particular three-phase unity power factor (UPF) current injection AC-DC converter. For this purpose, a dynamical model of the converter is developed using the state-space averaging method. Simulation results are used
IEEE Transactions on Industrial Electronics, 2004
Abstract In this paper, a new control strategy based on the pulsewidth-modulation technique is pr... more Abstract In this paper, a new control strategy based on the pulsewidth-modulation technique is proposed and applied to an active-current-injection-based unity-power-factor three-phase ac-dc converter. The control circuit of the converter consists of a multivariable inner current ...
… 2004. 26th Annual …, 2004
Growth in the outside plant equipment has prompted a demand for longer battery backup which is me... more Growth in the outside plant equipment has prompted a demand for longer battery backup which is met by an outdoor battery enclosure (OBE). Maximizing battery life with minimum maintenance is the objective for every provider. This work presents factors ...
In this paper, a new linear control strategy applied to a three-phase current injection AC-DC con... more In this paper, a new linear control strategy applied to a three-phase current injection AC-DC converter is presented. The proposed control scheme is based on the elaboration of the converter small-signal mathematical model, derived from the application of the state-space-averaging technique. The control design methodology of both current and voltage loops uses linear control theory. More precisely, each regulator's parameters
... In this paper, two control laws based respectively on hysteresis and Pulse-Width-Modulation (... more ... In this paper, two control laws based respectively on hysteresis and Pulse-Width-Modulation (PWM) techniques ... of each technique, in terms of the line current ripple and the switching frequency. ... simulation is accomplished using the Power System Blockset tool of Matlab/Siniulink ...
Site characterization and biofouling studies were conducted at a site about seven miles north of ... more Site characterization and biofouling studies were conducted at a site about seven miles north of St. Croix, U.S. Virgin Islands, during July to September, 1977. The devices basically consisted of aluminum pipes (8' long x 1'' ID) through which seawater flowed at rates of 3 or 6 ft secâ»Â¹. The units were mounted on the deck of a barge, moored
An analysis was made of nitrogen (N) and phosphorus (P) dynamics in the water column of the Patux... more An analysis was made of nitrogen (N) and phosphorus (P) dynamics in the water column of the Patuxent River, Maryland, over a 2 year cycle. Specifically, inorganic N and P assimilation were determined by isotopic tracer methods at 3 stations along the salinity gradient of the river on a monthly basis. The authors determined the concentrations of particulate N and
Canadian Journal of Public Health, 2002
The interactions between humans and the ocean are significant, and necessitate more comprehensive... more The interactions between humans and the ocean are significant, and necessitate more comprehensive study on an international scale. The world's oceans provide great health benefits to humans ranging from food and nutritional resources, to recreational opportunities and new treatments for human disease. However, recently, human health effects from exposure to substances present in the marine ecosystem such as synthetic organic chemicals (e.g., chlorobiphenyls, chlorinated dioxins and some industrial solvents), polycyclic aromatic hydrocarbons (PAHs), metals (both introduced and anthropogenic), marine toxins, and pathogens have been recorded and are of great concern. This paper reviews our state of knowledge of the interactions between oceans and human health and proposes indicators and a research strategy to investigate and monitor these relationships more closely. Four approaches to gathering information on indicators included here are: biomarkers; cellular pathology; physiological and behavioural responses; and changes in populations. All hold the potential to enhance our understanding of marine environmental quality and far-reaching effects on human health. Monitoring systems that include the rapid assessment of contaminants in the ecosystem and subsequent risk to human populations, with appropriate internationally distributed data bases, need to be developed and validated. Such tools would provide early detection of potential environmental threats, and enhance the ability to prevent human illness.
The Journal of Foraminiferal Research, 1983
... Light-en-hanced calcification in corals has been shown to be intimately linked with the photo... more ... Light-en-hanced calcification in corals has been shown to be intimately linked with the photosynthetic activity of the associated ... of laboratory experiments that clearly demonstrated the dependence of light-enhanced cal-cium uptake by the foraminifera, Archnias angularus. ...
Site characterization and biofouling studies were conducted at a site about seven miles north of ... more Site characterization and biofouling studies were conducted at a site about seven miles north of St. Croix, U.S. Virgin Islands, during July to September, 1977. The devices basically consisted of aluminum pipes (8' long x 1'' ID) through which seawater flowed at rates of 3 or 6 ft sec/sup -1/. The units were mounted on the deck of a barge, moored in water of depth about 4000 m, and seawater for the experiment was obtained from a depth of about 20 m ATP and carbon and nitrogen contents, microbial plate counts (bacteria, yeasts, filamentous fungi) were employed as measures of biofouling films within the aluminum pipes. Chlorophyll a and phaeo-pigment determinations indicated that viable and dead photosynthetic microbes were insignificant in the fouling films. No major differences in biofouling were observed between the two seawater flow rates, either in the CMU or RSMAS pipes. The general conclusion from the site characterization work is that the nutrient and microbial loa...
Applied and environmental microbiology, 1993
The Fe protein of nitrogenase in the marine nonheterocystous cyanobacterium Trichodesmium thiebau... more The Fe protein of nitrogenase in the marine nonheterocystous cyanobacterium Trichodesmium thiebautii is interconverted between two forms, which is reminiscent of the ADP-ribosylation described in the purple bacterium Rhodospirillum rubrum. In natural populations of T. thiebautii during the day, when nitrogenase activity (NA) is present and while photosynthetic rates are high, a low-molecular-mass form of the Fe protein is present. In the late afternoon, the low-molecular-mass form is partially converted to a higher-molecular-mass form (approximately equal distribution of high- and low-molecular-mass forms of the Fe protein subunits), concurrent with cessation of NA. Some of the higher-molecular-mass form persists through the night until the very early morning, when the lower-molecular-mass form appears. New synthesis of both the Fe and MoFe proteins of nitrogenase appears to occur at this time. The higher-molecular-mass form of the Fe protein is also produced rapidly in response to ...
ICECS 2000. 7th IEEE International Conference on Electronics, Circuits and Systems (Cat. No.00EX445), 2000
This paper presents a PWM-based control system associated with a single-phase two-stage boost rec... more This paper presents a PWM-based control system associated with a single-phase two-stage boost rectifier. Linear regulators are designed on the basis of a frequency-domain dynamical model of the converter. The input impedance and the dynamical susceptibility of the controlled system are then computed and analysed
2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230), 2001
A new nonlinear control technique applied to a current-injection three-phase rectifier (CITPR) is... more A new nonlinear control technique applied to a current-injection three-phase rectifier (CITPR) is proposed. Based on a nonlinear low-frequency mathematical model of the converter, the design procedure of the proposed control technique is divided into two steps. Firstly, two internal feedback loops for current shaping are elaborated on the basis of an input-output system linearization method. Secondly, in order to ensure the regulation of the output voltage, an external loop is then designed taking into account the inner current loops. The control strategy is evaluated by simulation using Matlab/Simulink toolbox. The numerical results obtained show the superiority of the new control technique in comparison to the linear one
2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230), 2001
In this paper, a new mathematical nonlinear model of a three-phase rectifier with current injecti... more In this paper, a new mathematical nonlinear model of a three-phase rectifier with current injection network is elaborated. The approach adopted is based on the state-space-averaging method A small-signal approximate linear dynamic model is then generated in the frequency domain. The model is validated using harmonic identification technique. Simulation results, using the Power System Blockset tool, are compared to the
INTELEC. Twenty-Second International Telecommunications Energy Conference (Cat. No.00CH37131), 2000
In this paper, a new control strategy based on the pulse-width-modulation (PWM) control technique... more In this paper, a new control strategy based on the pulse-width-modulation (PWM) control technique and using a single feedback current loop is proposed. The control scheme is applied to a particular three-phase unity power factor (UPF) current injection AC-DC converter. For this purpose, a dynamical model of the converter is developed using the state-space averaging method. Simulation results are used
IEEE Transactions on Industrial Electronics, 2004
Abstract In this paper, a new control strategy based on the pulsewidth-modulation technique is pr... more Abstract In this paper, a new control strategy based on the pulsewidth-modulation technique is proposed and applied to an active-current-injection-based unity-power-factor three-phase ac-dc converter. The control circuit of the converter consists of a multivariable inner current ...
… 2004. 26th Annual …, 2004
Growth in the outside plant equipment has prompted a demand for longer battery backup which is me... more Growth in the outside plant equipment has prompted a demand for longer battery backup which is met by an outdoor battery enclosure (OBE). Maximizing battery life with minimum maintenance is the objective for every provider. This work presents factors ...
In this paper, a new linear control strategy applied to a three-phase current injection AC-DC con... more In this paper, a new linear control strategy applied to a three-phase current injection AC-DC converter is presented. The proposed control scheme is based on the elaboration of the converter small-signal mathematical model, derived from the application of the state-space-averaging technique. The control design methodology of both current and voltage loops uses linear control theory. More precisely, each regulator's parameters
... In this paper, two control laws based respectively on hysteresis and Pulse-Width-Modulation (... more ... In this paper, two control laws based respectively on hysteresis and Pulse-Width-Modulation (PWM) techniques ... of each technique, in terms of the line current ripple and the switching frequency. ... simulation is accomplished using the Power System Blockset tool of Matlab/Siniulink ...
Site characterization and biofouling studies were conducted at a site about seven miles north of ... more Site characterization and biofouling studies were conducted at a site about seven miles north of St. Croix, U.S. Virgin Islands, during July to September, 1977. The devices basically consisted of aluminum pipes (8' long x 1'' ID) through which seawater flowed at rates of 3 or 6 ft secâ»Â¹. The units were mounted on the deck of a barge, moored
An analysis was made of nitrogen (N) and phosphorus (P) dynamics in the water column of the Patux... more An analysis was made of nitrogen (N) and phosphorus (P) dynamics in the water column of the Patuxent River, Maryland, over a 2 year cycle. Specifically, inorganic N and P assimilation were determined by isotopic tracer methods at 3 stations along the salinity gradient of the river on a monthly basis. The authors determined the concentrations of particulate N and