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Prodromos Daoutidis - One of the best experts on this subject based on the ideXlab platform.

  • modeling and control of a renewable hybrid energy system with hydrogen storage
    IEEE Transactions on Control Systems and Technology, 2014
    Co-Authors: Milana Trifkovic, Mehdi Sheikhzadeh, Khaled Nigim, Prodromos Daoutidis
    Abstract:

    This paper deals with system integration and controller design for power management of a stand-alone renewable energy (RE) hybrid system, which is at the construction stage in Lambton College (Sarnia, ON, Canada). The system consists of five main Components: photovoltaic arrays, wind turbine, electrolyzer, hydrogen storage tanks, and fuel cell. The model for each Process Component is developed, and all the Components are integrated in a Matlab/Simulink environment. A two-level control system is implemented, comprising a supervisory controller, which ensures the power balance between intermittent RE generation, energy storage, and dynamic load demand, as well as local controllers for the photovoltaic, wind, electrolyzer, and fuel cell unit. Simulations are performed to document the efficacy of the proposed power management strategy.

  • hierarchical control of a renewable hybrid energy system
    Conference on Decision and Control, 2012
    Co-Authors: Milana Trifkovic, Mehdi Sheikhzadeh, Khaled Nigim, Prodromos Daoutidis
    Abstract:

    This study deals with system integration and controller design for power management of a stand-alone renewable energy (RE) hybrid system, which is in its construction stage in Lambton College (Sarnia, Ontario, Canada). The system consists of five main Components: photovoltaic (PV) arrays, wind turbine, electrolyzer, hydrogen storage tanks, and fuel cell. The model for each Process Component is developed and all the hybrid energy system Components are integrated in a MATLAB/Simulink environment. A hierarchical control system is implemented, comprising of a supervisory controller, which ensures the power balance between intermittent renewable energy generation, energy storage and dynamic load demand, and local controllers for the PV, wind, electrolyzer and fuel cell units. A decentralized model predictive control (MPC) was designed and implemented on the electrolyzer and fuel cell to ensure optimal power flow.

Milana Trifkovic - One of the best experts on this subject based on the ideXlab platform.

  • modeling and control of a renewable hybrid energy system with hydrogen storage
    IEEE Transactions on Control Systems and Technology, 2014
    Co-Authors: Milana Trifkovic, Mehdi Sheikhzadeh, Khaled Nigim, Prodromos Daoutidis
    Abstract:

    This paper deals with system integration and controller design for power management of a stand-alone renewable energy (RE) hybrid system, which is at the construction stage in Lambton College (Sarnia, ON, Canada). The system consists of five main Components: photovoltaic arrays, wind turbine, electrolyzer, hydrogen storage tanks, and fuel cell. The model for each Process Component is developed, and all the Components are integrated in a Matlab/Simulink environment. A two-level control system is implemented, comprising a supervisory controller, which ensures the power balance between intermittent RE generation, energy storage, and dynamic load demand, as well as local controllers for the photovoltaic, wind, electrolyzer, and fuel cell unit. Simulations are performed to document the efficacy of the proposed power management strategy.

  • hierarchical control of a renewable hybrid energy system
    Conference on Decision and Control, 2012
    Co-Authors: Milana Trifkovic, Mehdi Sheikhzadeh, Khaled Nigim, Prodromos Daoutidis
    Abstract:

    This study deals with system integration and controller design for power management of a stand-alone renewable energy (RE) hybrid system, which is in its construction stage in Lambton College (Sarnia, Ontario, Canada). The system consists of five main Components: photovoltaic (PV) arrays, wind turbine, electrolyzer, hydrogen storage tanks, and fuel cell. The model for each Process Component is developed and all the hybrid energy system Components are integrated in a MATLAB/Simulink environment. A hierarchical control system is implemented, comprising of a supervisory controller, which ensures the power balance between intermittent renewable energy generation, energy storage and dynamic load demand, and local controllers for the PV, wind, electrolyzer and fuel cell units. A decentralized model predictive control (MPC) was designed and implemented on the electrolyzer and fuel cell to ensure optimal power flow.

Masahide Takadahidai - One of the best experts on this subject based on the ideXlab platform.

  • spectroscopic studies of extremely metal poor stars with the subaru high dispersion spectrograph ii the r Process elements including thorium
    The Astrophysical Journal, 2004
    Co-Authors: Satoshi Honda, Wako Aoki, Toshitaka Kajino, Hiroyasu Ando, Timothy C Beers, Hideyuki Izumiura, Kozo Sadakane, Masahide Takadahidai
    Abstract:

    We have obtained high-resolution, high signal-to-noise near-UV-blue spectra of 22 very metal-poor stars ([Fe/H] < -2.5) with the Subaru High Dispersion Spectrograph and measured the abundances of elements from C to Th. The metallicity range of the observed stars is -3.2 < [Fe/H] < -2.4. As found by previous studies, the star-to-star scatter in the measured abundances of neutron-capture elements in these stars is very large, much greater than could be assigned to observational errors, in comparison with the relatively small scatter in the α- and iron-peak elements. In spite of the large scatter in the ratios of the neutron-capture elements relative to iron, the abundance patterns of heavy neutron-capture elements (56 ≤ Z 72) are quite similar within our sample stars. The Ba/Eu ratios in the 11 very metal-poor stars in our sample in which both elements have been detected are nearly equal to that of the solar system r-Process Component. Moreover, the abundance patterns of the heavy neutron-capture elements (56 ≤ Z ≤ 70) in seven objects with clear enhancements of the neutron-capture elements are similar to that of the solar system r-Process Component. These results prove that heavy neutron-capture elements in these objects are primarily synthesized by the r-Process. In contrast, the abundance ratios of the light neutron-capture elements (38 ≤ Z ≤ 46) relative to the heavier ones (56 ≤ Z ≤ 70) exhibit a large dispersion. Our inspection of the correlation between Sr and Ba abundances in very metal-poor stars reveals that the dispersion of the Sr abundances clearly decreases with increasing Ba abundance. This trend is naturally explained by hypothesizing the existence of two Processes, one that produces Sr without Ba and another that produces Sr and Ba in similar proportions. This result should provide a strong constraint on the origin of the light neutron-capture elements at low metallicity. We have identified a new highly r-Process element enhanced, metal-poor star, CS 22183-031, a giant with [Fe/H] = -2.93 and [Eu/Fe] = +1.2. We also identified a new, moderately r-Process-enhanced, metal-poor star, CS 30306-132, a giant with [Fe/H] = -2.42 and [Eu/Fe] = +0.85. The abundance ratio of the radioactive element Th (Z = 90) relative to the stable rare-earth elements (e.g., Eu) in very metal-poor stars has been used as a cosmochronometer by a number of previous authors. Thorium is detected in seven stars in our sample, including four objects for which the detection of Th has already been reported. New detections of thorium have been made for the stars HD 6268, HD 110184, and CS 30306-132. The Th/Eu abundance ratios [log(Th/Eu)], are distributed over the range -0.10 to -0.59, with typical errors of 0.10 to 0.15 dex. In particular, the ratios in two stars, CS 31082-001 and CS 30306-132, are significantly higher than the ratio in the well-studied object CS 22892-052 and those of other moderately r-Process-enhanced metal-poor stars previously reported. Since these very metal-poor stars are believed to be formed in the early Galaxy, this result suggests that the abundance ratios between Th and stable rare-earth elements such as Eu, both of which are presumably produced by r-Process nucleosynthesis, may exhibit real star-to-star scatter, with implications for (1) the astrophysical sites of the r-Process, and (2) the use of Th/Eu as a cosmochronometer.

  • spectroscopic studies of extremly metal poor stars with subaru hds ii the r Process elements including thorium
    arXiv: Astrophysics, 2004
    Co-Authors: Satoshi Honda, Wako Aoki, Toshitaka Kajino, Hiroyasu Ando, Timothy C Beers, Hideyuki Izumiura, Kozo Sadakane, Masahide Takadahidai
    Abstract:

    We present the abundance analyses for the neutron-capture elements, and discuss the observed abundance distributions in very metal-poor stars with excesses of r-Process elements. As has been found by previous abundance studies, the star-to-star scatter in the abundances of neutron-capture elements are very large. The abundance patterns of the heavy neutron-capture elements (56 $\leq$ Z $\leq$ 70) in seven objects with moderate to large excesses of the neutron-capture elements are similar to that of the solar system r-Process Component. These results strongly suggest that the heavy neutron-capture elements in these objects are primarily synthesized by the r-Process. On the other hand, the abundance ratios of the light neutron-capture elements (38 $\leq$ Z $\leq$ 46) exhibit a rather large dispersion. Our inspection of the correlation between Sr and Ba abundances in very metal-poor stars reveals that the dispersion of the Sr abundances clearly decreases with increasing Ba abundance. This results support previous suggestions that the light neutron-capture elements are likely to have been produced in different astrophysical sites from those associated with the production of the heavier ones. The Th/Eu abundance ratios (log(Th/Eu)) measured for the seven r-Process-enhanced stars range from -0.10 to -0.59. Since these very metal-poor stars are believed to be formed in the early Galaxy, this result means that a small dispersion appears in the abundance ratios between Th and rare-earth elements, such as Eu, in very metal-poor stars. In order to apply the Th/Eu ratios to estimates of stellar ages, further understanding for the Th production by the r-Process nucleosynthesis is required.

William R Ketterhagen - One of the best experts on this subject based on the ideXlab platform.

  • simulation of powder flow in a lab scale tablet press feed frame effects of design and operating parameters on measures of tablet quality
    Powder Technology, 2015
    Co-Authors: William R Ketterhagen
    Abstract:

    Abstract The feed frame of a pharmaceutical tablet press is an important Process Component critical in defining both the total tablet mass and the amount of the active pharmaceutical ingredient (API) within the tablets. In addition to these quantities, the mechanical agitation of the feeder can cause attrition or over-lubrication of the powder blend or granulation flowing through the device. In order to better understand these effects, the discrete element method is used to model powder flow in a single paddle wheel feed frame of a laboratory-scale tablet press with varying particle, Process, and equipment parameters. Results show that widely varying particle flow patterns and residence time distributions are achieved for varying paddle wheel shape, rotation direction, and rotation speed. Faster paddle wheel speeds generally lead to more uniform tablet masses whereas slower paddle wheel speeds perform less work on the particles (a surrogate for attrition) and move the particles a smaller distance (a surrogate for the extent of lubrication) in the feed frame before they enter a die and are compressed into a tablet. Finally, the effects of paddle wheel design and powder cohesion are also described.

Mehdi Sheikhzadeh - One of the best experts on this subject based on the ideXlab platform.

  • modeling and control of a renewable hybrid energy system with hydrogen storage
    IEEE Transactions on Control Systems and Technology, 2014
    Co-Authors: Milana Trifkovic, Mehdi Sheikhzadeh, Khaled Nigim, Prodromos Daoutidis
    Abstract:

    This paper deals with system integration and controller design for power management of a stand-alone renewable energy (RE) hybrid system, which is at the construction stage in Lambton College (Sarnia, ON, Canada). The system consists of five main Components: photovoltaic arrays, wind turbine, electrolyzer, hydrogen storage tanks, and fuel cell. The model for each Process Component is developed, and all the Components are integrated in a Matlab/Simulink environment. A two-level control system is implemented, comprising a supervisory controller, which ensures the power balance between intermittent RE generation, energy storage, and dynamic load demand, as well as local controllers for the photovoltaic, wind, electrolyzer, and fuel cell unit. Simulations are performed to document the efficacy of the proposed power management strategy.

  • hierarchical control of a renewable hybrid energy system
    Conference on Decision and Control, 2012
    Co-Authors: Milana Trifkovic, Mehdi Sheikhzadeh, Khaled Nigim, Prodromos Daoutidis
    Abstract:

    This study deals with system integration and controller design for power management of a stand-alone renewable energy (RE) hybrid system, which is in its construction stage in Lambton College (Sarnia, Ontario, Canada). The system consists of five main Components: photovoltaic (PV) arrays, wind turbine, electrolyzer, hydrogen storage tanks, and fuel cell. The model for each Process Component is developed and all the hybrid energy system Components are integrated in a MATLAB/Simulink environment. A hierarchical control system is implemented, comprising of a supervisory controller, which ensures the power balance between intermittent renewable energy generation, energy storage and dynamic load demand, and local controllers for the PV, wind, electrolyzer and fuel cell units. A decentralized model predictive control (MPC) was designed and implemented on the electrolyzer and fuel cell to ensure optimal power flow.