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Appendage

The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform

Mohammad Azadi – 1st expert on this subject based on the ideXlab platform

  • Dynamics and control of a smart flexible satellite moving in an orbit
    Multibody System Dynamics, 2015
    Co-Authors: Mohammad Eghtesad, Mohammad Azadi, S. Ahmad Fazelzadeh, E. Azadi

    Abstract:

    In this paper, the three axes maneuver control and vibration suppression of a smart flexible satellite moving in a circular orbit are studied. First, by using Lagrange–Rayleigh–Ritz technique and assumed mode method, the governing equations of a flexible satellite with PZT (lead zirconate titanate) piezoelectric patches are obtained. The flexibility of the Appendages and the assumption of a large angle trajectory cause the governing equations to be nonlinear and coupled. The piezoelectric layers, attached to both sides of the Appendages, are considered as sensors and actuators. A thorough look at the resulting equations reveals that the flexible satellite dynamics that include the Appendage vibrations and rigid maneuver occur in two different time scales. By using the singular perturbation theory, the system dynamics is divided into two fast and slow subsystems. The slow and fast subsystems are associated with rigid motion dynamics and flexible Appendages dynamics, respectively. A hybrid controller, which is proposed for use, consists of a variable structure controller (VSC) for maneuvering control of the slow subsystem, and a Lyapunov based controller for vibration suppression of the fast subsystem. The stability of the controllers is studied using the Lyapunov stability theory. Finally, the system behavior is simulated and the simulation results show the efficient performance of the proposed hybrid controller.

  • Vibration suppression of smart nonlinear flexible Appendages of a rotating satellite by using hybrid adaptive sliding mode/Lyapunov control
    JVC Journal of Vibration and Control, 2013
    Co-Authors: E. Azadi, Mohammad Eghtesad, S. Ahmad Fazelzadeh, Mohammad Azadi

    Abstract:

    In this paper, a hybrid adaptive sliding mode/Lyapunov controller is designed for both the rotational maneuver and the vibration control of smart flexible Appendages of a satellite moving in a circular orbit. The satellite is considered as a rigid hub and two flexible Appendages with attached piezoelectric layers as sensors and actuators. Each Appendage is considered as a nonlinear beam undergoing large deflection. These governing equations of motion are obtained using a Lagrange-Rayleigh-Ritz technique and assumed mode method. The dynamic equations of motion are nonlinear and coupled due to the large angle trajectory and Appendages large deflection. A through look at the resulting equations shows that the flexible satellite dynamics including the vibrations of the Appendages and their rigid maneuver occur in two different time scales. Using the singular perturbation theory, the dynamics of the flexible satellite are divided into two slow and fast subsystems, the former associated with rigid-body maneuver, while the latter is a result of the vibrations of the Appendages. Use of this hybrid controller allows us to cope with parameters uncertainty and disturbances of the system. The stability of the hybrid controller is studied by using the Lyapunov approach. Finally, the whole system is modeled and the simulation results show the efficient performance of the proposed hybrid controller. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Marja L Mikkola – 2nd expert on this subject based on the ideXlab platform

  • TNF superfamily in skin Appendage development.
    Cytokine & Growth Factor Reviews, 2008
    Co-Authors: Marja L Mikkola

    Abstract:

    Abstract The development of skin Appendages such as hairs, teeth, and mammary glands is regulated by signaling molecules of the Wnt, FGF, TGFβ, and Hedgehog pathways. Last decade has also revealed a pivotal role for the TNF family ligand ectodysplasin (Eda) in multiple steps of epithelial Appendage morphogenesis, from initiation to differentiation. Surprisingly, other members of the TNF superfamily such as Rank ligand, lymphotoxins, and TNF have recently been linked with specific aspects of skin Appendage biology including branching of the mammary gland, hair shaft formation, and hair follicle cycling. This review focuses on the novel discoveries of Eda and other TNF related cytokines in skin Appendage development made since the previous review on this topic in Cytokine and Growth Factor reviews in 2003.

  • TNF superfamily in skin Appendage development.
    Cytokine & growth factor reviews, 2008
    Co-Authors: Marja L Mikkola

    Abstract:

    The development of skin Appendages such as hairs, teeth, and mammary glands is regulated by signaling molecules of the Wnt, FGF, TGFbeta, and Hedgehog pathways. Last decade has also revealed a pivotal role for the TNF family ligand ectodysplasin (Eda) in multiple steps of epithelial Appendage morphogenesis, from initiation to differentiation. Surprisingly, other members of the TNF superfamily such as Rank ligand, lymphotoxins, and TNF have recently been linked with specific aspects of skin Appendage biology including branching of the mammary gland, hair shaft formation, and hair follicle cycling. This review focuses on the novel discoveries of Eda and other TNF related cytokines in skin Appendage development made since the previous review on this topic in Cytokine and Growth Factor reviews in 2003.

  • The Mammary Bud as a Skin Appendage: Unique and Shared Aspects of Development
    Journal of Mammary Gland Biology and Neoplasia, 2006
    Co-Authors: Marja L Mikkola, Sarah E. Millar

    Abstract:

    Like other skin Appendages, the embryonic mammary gland develops via extensive epithelial–mesenchymal interactions. Early stages in embryonic mammary development strikingly resemble analogous steps in the development of hair follicles and teeth. In each case the first morphological sign of development is a localized thickening in the surface epithelium that subsequently invaginates to form a mammary, hair follicle or tooth bud. Similar sets of intersecting signaling pathways are involved in patterning the mammary, hair follicle and dental epithelium, directing placode formation, and controlling bud invagination. Despite these similarities, subsequent events in the formation of these Appendages are diverse. The mammary bud extends to form a sprout that begins to branch upon contact with the mammary fat pad. Hair follicles also extend into the underlying mesenchyme, but instead of branching, hair follicle epithelium folds around a condensation of dermal cells. In contrast, teeth undergo a more complex folding morphogenesis. Here, we review what is known of the molecular and cellular mechanisms controlling early steps in the development of these organs, attempt to unravel both common themes and unique aspects that can begin to explain the diversity of Appendage formation, and discuss human genetic diseases that affect Appendage morphogenesis.

E. Azadi – 3rd expert on this subject based on the ideXlab platform

  • Dynamics and control of a smart flexible satellite moving in an orbit
    Multibody System Dynamics, 2015
    Co-Authors: Mohammad Eghtesad, Mohammad Azadi, S. Ahmad Fazelzadeh, E. Azadi

    Abstract:

    In this paper, the three axes maneuver control and vibration suppression of a smart flexible satellite moving in a circular orbit are studied. First, by using Lagrange–Rayleigh–Ritz technique and assumed mode method, the governing equations of a flexible satellite with PZT (lead zirconate titanate) piezoelectric patches are obtained. The flexibility of the Appendages and the assumption of a large angle trajectory cause the governing equations to be nonlinear and coupled. The piezoelectric layers, attached to both sides of the Appendages, are considered as sensors and actuators. A thorough look at the resulting equations reveals that the flexible satellite dynamics that include the Appendage vibrations and rigid maneuver occur in two different time scales. By using the singular perturbation theory, the system dynamics is divided into two fast and slow subsystems. The slow and fast subsystems are associated with rigid motion dynamics and flexible Appendages dynamics, respectively. A hybrid controller, which is proposed for use, consists of a variable structure controller (VSC) for maneuvering control of the slow subsystem, and a Lyapunov based controller for vibration suppression of the fast subsystem. The stability of the controllers is studied using the Lyapunov stability theory. Finally, the system behavior is simulated and the simulation results show the efficient performance of the proposed hybrid controller.

  • Vibration suppression of smart nonlinear flexible Appendages of a rotating satellite by using hybrid adaptive sliding mode/Lyapunov control
    JVC Journal of Vibration and Control, 2013
    Co-Authors: E. Azadi, Mohammad Eghtesad, S. Ahmad Fazelzadeh, Mohammad Azadi

    Abstract:

    In this paper, a hybrid adaptive sliding mode/Lyapunov controller is designed for both the rotational maneuver and the vibration control of smart flexible Appendages of a satellite moving in a circular orbit. The satellite is considered as a rigid hub and two flexible Appendages with attached piezoelectric layers as sensors and actuators. Each Appendage is considered as a nonlinear beam undergoing large deflection. These governing equations of motion are obtained using a Lagrange-Rayleigh-Ritz technique and assumed mode method. The dynamic equations of motion are nonlinear and coupled due to the large angle trajectory and Appendages large deflection. A through look at the resulting equations shows that the flexible satellite dynamics including the vibrations of the Appendages and their rigid maneuver occur in two different time scales. Using the singular perturbation theory, the dynamics of the flexible satellite are divided into two slow and fast subsystems, the former associated with rigid-body maneuver, while the latter is a result of the vibrations of the Appendages. Use of this hybrid controller allows us to cope with parameters uncertainty and disturbances of the system. The stability of the hybrid controller is studied by using the Lyapunov approach. Finally, the whole system is modeled and the simulation results show the efficient performance of the proposed hybrid controller. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.