Current Search: Wind-pressure (x)
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- Title
- Control of response of tall multi-story buildings under wind excitation.
- Creator
- Qiu, Xin., Florida Atlantic University, Lin, Y. K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Theoretical investigation is carried out into the extent to which floor accelerations of a wind-excited tall building can be reduced by increasing damping in those components in a building which are generally regarded to be non-structural elements, and by using active control. The wind loads are modeled as stochastic processes, which are correlation-stationary in time. Only the drag wind forces are considered in the analyses. The spectral densities and cross-spectral densities of two commonly...
Show moreTheoretical investigation is carried out into the extent to which floor accelerations of a wind-excited tall building can be reduced by increasing damping in those components in a building which are generally regarded to be non-structural elements, and by using active control. The wind loads are modeled as stochastic processes, which are correlation-stationary in time. Only the drag wind forces are considered in the analyses. The spectral densities and cross-spectral densities of two commonly used models, proposed by Davenport and by Simiu, are compared. The Davenport spectrum is used in the numerical calculation for illustration purposes. Several structural models are discussed: an ideal spatially periodic model, an ideal piece-wise spatially periodic model, a nominal spatially periodic model with random disorder in periodicity, and an ideal spatially periodic model equipped with an active mass damper control system. The problems are formulated using the transfer matrix approach in the frequency domain. Analytical solutions are obtained for the spectral densities and the mean-square values of the floor accelerations and those of the active control force. Numerical examples are given for illustration.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/12495
- Subject Headings
- Tall buildings--Aerodynamics, Wind-pressure, Damping (Mechanics)
- Format
- Document (PDF)
- Title
- On long-term net flow over Great Bahama Bank.
- Creator
- Smith, Ned P.
- Date Issued
- 1995
- PURL
- http://purl.flvc.org/FCLA/DT/3321410
- Subject Headings
- Water currents--Measurement, Great Bahama Bank (Bahamas), Wind-pressure--Measurement, Salinity
- Format
- Document (PDF)
- Title
- Experimental determination of motion-induced force coefficients of long-span bridge models in a water channel.
- Creator
- Wei, Li., Florida Atlantic University, Su, Tsung-Chow, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Wind loads on a bridge may be classified into two types: the buffeting loads and the self-excited loads. The research reported in this thesis is concerned with experimental determination of the self-excited loads in the frequency domain, in particular, their non-dimensional coefficients, called flutter derivatives. The experiments were conducted in a water channel with water substituting for air. Five bridge-section models of different shapes were tested, each of which was driven to move...
Show moreWind loads on a bridge may be classified into two types: the buffeting loads and the self-excited loads. The research reported in this thesis is concerned with experimental determination of the self-excited loads in the frequency domain, in particular, their non-dimensional coefficients, called flutter derivatives. The experiments were conducted in a water channel with water substituting for air. Five bridge-section models of different shapes were tested, each of which was driven to move harmonically by linkages, and the forces on the linkages were measured to determine the fluid loads. A thin-plate model, simulating an airfoil, was also tested and the results were compared with those obtained from the thin airfoil theory. The setup of the experiments and data acquisition, processing and analysis are presented herein.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14959
- Subject Headings
- Bridges, Long-span, Wind-pressure, Bridges--Vibration, Structural dynamics
- Format
- Document (PDF)
- Title
- Wind Feedforward Control of a USV.
- Creator
- Qu, Huajin, von Ellenrieder, Karl, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
In this research, a wind feedforward (FF) controller has been developed to augment closed loop feedback controllers for the position and heading station keeping control of Unmanned Surface Vehicles (USVs). The performance of the controllers was experimentally tested using a 16 foot USV in an outdoor marine environment. The FF controller was combined with three nonlinear feedback controllers, a Proportional–Derivative (PD) controller, a Backstepping (BS) controller, and a Sliding mode (SM)...
Show moreIn this research, a wind feedforward (FF) controller has been developed to augment closed loop feedback controllers for the position and heading station keeping control of Unmanned Surface Vehicles (USVs). The performance of the controllers was experimentally tested using a 16 foot USV in an outdoor marine environment. The FF controller was combined with three nonlinear feedback controllers, a Proportional–Derivative (PD) controller, a Backstepping (BS) controller, and a Sliding mode (SM) controller, to improve the station-keeping performance of the USV. To address the problem of wind model uncertainties, adaptive wind feedforward (AFF) control schemes are also applied to the FF controller, and implemented together with the BS and SM feedback controllers. The adaptive law is derived using Lyapunov Theory to ensure stability. On-water station keeping tests of each combination of FF and feedback controllers were conducted in the U.S. Intracoastal Waterway in Dania Beach, FL USA. Five runs of each test condition were performed; each run lasted at least 10 minutes. The experiments were conducted in Sea State 1 with an average wind speed of between 1 to 4 meters per second and significant wave heights of less than 0.2 meters. When the performance of the controllers is compared using the Integral of the Absolute Error (IAE) of position criterion, the experimental results indicate that the BS and SM feedback controllers significantly outperform the PD feedback controller (e.g. a 33% and a 44% decreases in the IAE, respectively). It is also found that FF is beneficial for all three feedback controllers and that AFF can further improve the station keeping performance. For example, a BS feedback control combined with AFF control reduces the IAE by 25% when compared with a BS feedback controller combined with a non-adaptive FF controller. Among the eight combinations of controllers tested, SM feedback control combined with AFF control gives the best station keeping performance with an average position and heading error of 0.32 meters and 4.76 degrees, respectively.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004623, http://purl.flvc.org/fau/fd/FA00004623
- Subject Headings
- Wind turbines--Control., Adaptive control systems., Adaptive signal processing., Intelligent control systems., Wind-pressure., Intelligent sensors.
- Format
- Document (PDF)