A range of methodologies exist for estimating nonlinear responses of structural systems using num... more A range of methodologies exist for estimating nonlinear responses of structural systems using numerical simulations. However, efforts in relation to experimental methods in this regard still warrant further investigation. This paper presents an approach for assessing structural nonlinearities using the extremes of dynamic responses of the structural system under consideration. The approach allows revisiting and parameter tuning of theoretical models of structures based on experimental studies. A single degree of freedom system was excited in this study using broadband input excitations and the output dynamic responses were measured using different devices. The type and extent of experimentation required for implementation of the presented technique was investigated along with the effects of the estimates of the measured variables and the effects related to different measurement devices.
Study of wind farms is an area of active research. Researchers have proposed simplified wind farm... more Study of wind farms is an area of active research. Researchers have proposed simplified wind farm models that define the wake structure in a wind farm and how they affect the performance of the wind turbines. Interestingly, these models do not take into account an important aspect of fluid flow, i.e., the fluid–structure interaction (FSI) between the turbines and the wind, which has an important role to play. This motivated researchers to implement numerical analysis tools to model the geometry of the wind turbines in computational fluid dynamics (CFD) based models of a wind farm in order to better understand the wake structure and study the performance of the wind farms. However, modeling the complex geometry of the blades and the turbines makes these models computationally expensive. In this paper, we propose an FSI methodology which can simplify the blade resolving CFD models and eliminate the requirement for modeling these complex geometries during preliminary engineering phase....
Automated detection and recognition of traffic signals are of great significance in railway syste... more Automated detection and recognition of traffic signals are of great significance in railway systems. Autonomous driving solutions are well established for urban rail transportation systems. Many metro lines in service worldwide have reached the highest grade of automation where the train is automatically operated without any staff on board. However, autonomous driving is still an open challenge for mainline trains, due to the complexity of the mainline environment. In this context, automated recognition of wayside signals can help to minimise the risk of human error owing to low visibility and fatigue. It represents a key step towards the fully autonomous train. In this article we present a deep learning based approach for the above task. The You Only Look Once (YOLOv5) is used for detection and recognition of wayside signals. A heuristic is used to recognise blinking states. We consider FRSign dataset, a large collection of over 100,000 images of traffic signals from some of the tr...
Short-time, abrupt events—such as earthquakes and other shock loadings—often lead to damage that ... more Short-time, abrupt events—such as earthquakes and other shock loadings—often lead to damage that is difficult to detect in structures using output-only vibration measurements. The time-variant transmissibility is proposed to tackle this problem. The approach is based on two-dimensional wavelet power spectra. The time-frequency transmissibility and relevant coherence function are used for structural damage detection in structural elements in buildings. Numerical simulations and experimental tests are used in these investigations. The results are compared with the classical transmissibility and time-variant input-output wavelet approach. The paper shows that output-only measurements and wavelet-based transmissibility can be used to monitor abrupt damage-related changes to structural dynamics.
In this work, an algorithm for the scheduling of household appliances to reduce the energy cost a... more In this work, an algorithm for the scheduling of household appliances to reduce the energy cost and the peak-power consumption is proposed. The system architecture of a home energy management system (HEMS) is presented to operate the appliances. The dynamics of thermal and non-thermal appliances is represented into state-space model to formulate the scheduling task into a mixed-integer-linear-programming (MILP) optimization problem. Model predictive control (MPC) strategy is used to operate the appliances in real-time. The HEMS schedules the appliances in a dynamic manner without any a priori knowledge of the load-consumption pattern. At the same time, HEMS responds to the real-time electricity market and the external environmental conditions (solar radiation, ambient temperature etc). Simulation results exhibit the benefits of proposed HEMS by showing the reduction of up to 47% in electricity cost and up to 48% in peak power consumption.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2017
Bounds on estimates of wave heights (valid for large amplitudes) from pressure and flow measureme... more Bounds on estimates of wave heights (valid for large amplitudes) from pressure and flow measurements at an arbitrary intermediate depth have been provided. Two-dimensional irrotational steady water waves over a flat bed with a finite depth in the presence of underlying uniform currents have been considered in the analysis. Five different upper bounds based on a combination of pressure and velocity field measurements have been derived, though there is only one available lower bound on the wave height in the case of the speed of current greater than or less than the wave speed. This article is part of the theme issue ‘Nonlinear water waves’.
An experimental investigation into the passive damping properties of various fluids, including ma... more An experimental investigation into the passive damping properties of various fluids, including magnetorheological (MR) fluid, in a tuned liquid column damper (TLCD) is undertaken. The coefficient of head loss for different fluids used in TLCDs to reduce structural responses in single-degree-of-freedom (SDOF) structures subjected to base excitation is experimentally determined. Experimental results are used to calculate the nonlinear coefficient of head loss based on a theoretical formulation. The numerical simulations of the responses of the structure-TLCD system with various fluids used in TLCDs are validated with the experimental results. Water has traditionally been used in TLCDs although semiactive control and additional functional requirements (antifreezing) of TLCDs can be achieved with MR fluids and glycol as resident TLCD liquids, respectively. The semiactive MR-TLCD works by utilizing the ability to change the damping properties (i.e., head loss) of the MR fluid by applying...
In the last decades the use of composite materials has increased especially in light-weight struc... more In the last decades the use of composite materials has increased especially in light-weight structural applications, such as wind turbine blades. These structural components require reliable methods for damage assessment to avoid progressive or sudden and catastrophic failures. In this paper, a model of a fiber-reinforced composite cantilever beam with a bridged edge crack, representing an existing damage state, is considered. The composite matrix of the beam exhibits a linear-elastic behavior, whereas a fracture mechanics-based theoretical model incorporating the crack bridging forces in the fiber-reinforcement is used to describe the elastic-plastic response of the cracked beam section subjected to bending moment. This model is employed to simulate the nonlinear static deflection of cantilever beams with different crack locations and depths. Wavelet and kurtosis-based identification techniques are employed in the localization and calibration of this damage in presence of noise. Th...
A range of methodologies exist for estimating nonlinear responses of structural systems using num... more A range of methodologies exist for estimating nonlinear responses of structural systems using numerical simulations. However, efforts in relation to experimental methods in this regard still warrant further investigation. This paper presents an approach for assessing structural nonlinearities using the extremes of dynamic responses of the structural system under consideration. The approach allows revisiting and parameter tuning of theoretical models of structures based on experimental studies. A single degree of freedom system was excited in this study using broadband input excitations and the output dynamic responses were measured using different devices. The type and extent of experimentation required for implementation of the presented technique was investigated along with the effects of the estimates of the measured variables and the effects related to different measurement devices.
Study of wind farms is an area of active research. Researchers have proposed simplified wind farm... more Study of wind farms is an area of active research. Researchers have proposed simplified wind farm models that define the wake structure in a wind farm and how they affect the performance of the wind turbines. Interestingly, these models do not take into account an important aspect of fluid flow, i.e., the fluid–structure interaction (FSI) between the turbines and the wind, which has an important role to play. This motivated researchers to implement numerical analysis tools to model the geometry of the wind turbines in computational fluid dynamics (CFD) based models of a wind farm in order to better understand the wake structure and study the performance of the wind farms. However, modeling the complex geometry of the blades and the turbines makes these models computationally expensive. In this paper, we propose an FSI methodology which can simplify the blade resolving CFD models and eliminate the requirement for modeling these complex geometries during preliminary engineering phase....
Automated detection and recognition of traffic signals are of great significance in railway syste... more Automated detection and recognition of traffic signals are of great significance in railway systems. Autonomous driving solutions are well established for urban rail transportation systems. Many metro lines in service worldwide have reached the highest grade of automation where the train is automatically operated without any staff on board. However, autonomous driving is still an open challenge for mainline trains, due to the complexity of the mainline environment. In this context, automated recognition of wayside signals can help to minimise the risk of human error owing to low visibility and fatigue. It represents a key step towards the fully autonomous train. In this article we present a deep learning based approach for the above task. The You Only Look Once (YOLOv5) is used for detection and recognition of wayside signals. A heuristic is used to recognise blinking states. We consider FRSign dataset, a large collection of over 100,000 images of traffic signals from some of the tr...
Short-time, abrupt events—such as earthquakes and other shock loadings—often lead to damage that ... more Short-time, abrupt events—such as earthquakes and other shock loadings—often lead to damage that is difficult to detect in structures using output-only vibration measurements. The time-variant transmissibility is proposed to tackle this problem. The approach is based on two-dimensional wavelet power spectra. The time-frequency transmissibility and relevant coherence function are used for structural damage detection in structural elements in buildings. Numerical simulations and experimental tests are used in these investigations. The results are compared with the classical transmissibility and time-variant input-output wavelet approach. The paper shows that output-only measurements and wavelet-based transmissibility can be used to monitor abrupt damage-related changes to structural dynamics.
In this work, an algorithm for the scheduling of household appliances to reduce the energy cost a... more In this work, an algorithm for the scheduling of household appliances to reduce the energy cost and the peak-power consumption is proposed. The system architecture of a home energy management system (HEMS) is presented to operate the appliances. The dynamics of thermal and non-thermal appliances is represented into state-space model to formulate the scheduling task into a mixed-integer-linear-programming (MILP) optimization problem. Model predictive control (MPC) strategy is used to operate the appliances in real-time. The HEMS schedules the appliances in a dynamic manner without any a priori knowledge of the load-consumption pattern. At the same time, HEMS responds to the real-time electricity market and the external environmental conditions (solar radiation, ambient temperature etc). Simulation results exhibit the benefits of proposed HEMS by showing the reduction of up to 47% in electricity cost and up to 48% in peak power consumption.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2017
Bounds on estimates of wave heights (valid for large amplitudes) from pressure and flow measureme... more Bounds on estimates of wave heights (valid for large amplitudes) from pressure and flow measurements at an arbitrary intermediate depth have been provided. Two-dimensional irrotational steady water waves over a flat bed with a finite depth in the presence of underlying uniform currents have been considered in the analysis. Five different upper bounds based on a combination of pressure and velocity field measurements have been derived, though there is only one available lower bound on the wave height in the case of the speed of current greater than or less than the wave speed. This article is part of the theme issue ‘Nonlinear water waves’.
An experimental investigation into the passive damping properties of various fluids, including ma... more An experimental investigation into the passive damping properties of various fluids, including magnetorheological (MR) fluid, in a tuned liquid column damper (TLCD) is undertaken. The coefficient of head loss for different fluids used in TLCDs to reduce structural responses in single-degree-of-freedom (SDOF) structures subjected to base excitation is experimentally determined. Experimental results are used to calculate the nonlinear coefficient of head loss based on a theoretical formulation. The numerical simulations of the responses of the structure-TLCD system with various fluids used in TLCDs are validated with the experimental results. Water has traditionally been used in TLCDs although semiactive control and additional functional requirements (antifreezing) of TLCDs can be achieved with MR fluids and glycol as resident TLCD liquids, respectively. The semiactive MR-TLCD works by utilizing the ability to change the damping properties (i.e., head loss) of the MR fluid by applying...
In the last decades the use of composite materials has increased especially in light-weight struc... more In the last decades the use of composite materials has increased especially in light-weight structural applications, such as wind turbine blades. These structural components require reliable methods for damage assessment to avoid progressive or sudden and catastrophic failures. In this paper, a model of a fiber-reinforced composite cantilever beam with a bridged edge crack, representing an existing damage state, is considered. The composite matrix of the beam exhibits a linear-elastic behavior, whereas a fracture mechanics-based theoretical model incorporating the crack bridging forces in the fiber-reinforcement is used to describe the elastic-plastic response of the cracked beam section subjected to bending moment. This model is employed to simulate the nonlinear static deflection of cantilever beams with different crack locations and depths. Wavelet and kurtosis-based identification techniques are employed in the localization and calibration of this damage in presence of noise. Th...
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