Search results for "Dynamic response"
showing 10 items of 11 documents
Characterization of BOLD-fMRI signal during a verbal fluency paradigm in patients with intracerebral tumors affecting the frontal lobe.
2002
Previous studies have indicated that the BOLD-fMRI signal can be modified by tumor processes in close vicinity to functional brain areas. This effect has been investigated primarily for the perirolandic area but there is only a limited number of studies concerning frontal cortical regions. Therefore, the aim of the current study was to characterize BOLD-fMRI signal and activation patterns in patients with frontal brain tumors while performing a verbal fluency task. Six patients (ages 31-56 years) suffering from frontal (5 left sided and 1 right sided) intracerebral tumors were examined with fMRI while performing a verbal fluency task in a blocked paradigm design. Eight healthy volunteers se…
A Strain Sensing Structural Health Monitoring System for Delaminated Composite Structures
2012
Structural Health Monitoring (SHM) for composite materials is becoming a primary task due to their extended use in safety critical applications. Different methods, based on the use of piezoelectric transducers as well as of fiber optics, has been successfully proposed to detect and monitor damage in composite structural components with particular attention focused on delamination cracks.In the present paper a Structural Health Monitoring model, based on the use of piezoelectric sensors, already proposed by the authors for isotropic damaged components, is extended to delaminated composite structures. The dynamic behavior of the host damaged structure and the bonded piezoelectric sensors is m…
A perturbation approach for the response of dynamically modified structural systems
1998
The problem of the structural analysis under changes of dynamical parameters is of particular interest. This is due to the fact that often the real structures are different from the predicted ones. In this paper, an unconditionally stable step-by-step procedure, able to evaluate the deterministic response of linear structures with modifications, is presented. The proposed procedure requires the evaluation of the transition matrix, which is the fundamental operator of the step-by-step solution, by means of a perturbation approach. This technique overcomes the difficulties connected with the evaluation of the eigenproperties of the modified structures usually required to obtain the transition…
Dynamic analysis of damaged magnetoelectroelastic laminated structures
2010
In the present paper a boundary element analysis of the dynamic response of damaged magnetoelectroelastic laminate structures is presented. The problem is formulated employing generalized displacements. The mass matrix is computed by the Dual Reciprocity Method. Due to the non-homogeneous nature of the laminate the multidomain boundary element technique is employed which also straightforwardly allows the modeling of interface cracks and delaminations. The multidomain boundary element technique is implemented with imperfect interlaminar interfaces and unilateral interface conditions to prevent the physical inconsistence of the overlapping between interface nodes belonging to two different pl…
Coupling between simultaneously recorded BOLD response and neuronal activity in the rat somatosensory cortex
2007
Abstract Understanding the link between the hemodynamic response and the underlying neuronal activity is important for interpreting functional magnetic resonance (fMRI) signals in human and animal studies. Simultaneous electrophysiological and functional imaging measurements provide a knowledge of information processing and communication in the brain with high spatial and temporal resolution. In this study, a range of neural and blood oxygenation level-dependent (BOLD) responses were elicited in the rat somatosensory cortex by changing the type of anesthesia (urethane or alpha-chloralose) and the electrical forepaw stimulus frequency (1–15 Hz). Duration of the stimulus was 30 s. Electrical …
Design, modelling, and analysis of a large floating dock for spar floating wind turbine installation
2020
Installation of floating wind turbines at the offshore site is a challenging task. A significant part of the time efficiency and costs are related to the installation methods which are sensitive to weather conditions. This study investigates a large floating dock concept, which can be used to shield a floating wind turbine during installation of tower, nacelle, and rotor onto a spar foundation. In this paper, the concept is described in detail, and a design optimisation is carried out using simple design constraints. Hydrodynamic analysis and dynamic response analysis of the coupled system of the optimum dock and spar are conducted. Two spars of different sizes are considered, and the motio…
A correction method for dynamic analysis of linear continuous systems
2005
A method to improve the dynamic response analysis of continuous classically damped linear system is proposed. As in fact usually, following a classical approach, a reduced number of eigenfunctions are accounted for and the response is evaluated by integrating the uncoupled differential equations of motion in modal space, neglecting the contribution of high frequency modes (truncation procedure). Here, starting from the given system, it is proposed to set up two differential equations governing the motion of two new continuous systems: the first one contains only the first m non-zero eigenvalues of the given system and the second one contains the remainder non-zero infinity - m eigenvalues. …
Integrated thermodynamic and electrical modelling of a variable-speed reversible heat pump: analysis of the cooling mode operation
2022
Variable-speed reversible heat pumps are increasingly adopted for space heating and cooling in residential and tertiary sectors. It is recognized that these systems will play a key role in medium- and small-scale 4th generation district heating and cooling networks. Indeed, with the high penetration of intermittent renewable energy sources, such technology could help reduce issues related to the surplus of electricity from renewable energy sources by converting it into heat or cold. To reliably assess the benefits achievable in these emerging applications, it is necessary to develop models which can simulate not only the steady-state operation but also the dynamic response of the system wit…
Flow characteristics and dynamic responses of a parked straight‐bladed vertical axis wind turbine
2019
Abstract With the development of urbanization and the application of renewable energy, wind turbine is becoming an important approach for wind energy reservation and utilization. This study provides a numerical investigation on understanding the surface pressure distribution, flow characteristics and dynamic responses of a parked straight‐bladed vertical axis wind turbine (VAWT), which is helpful for its design. Together with the two‐way coupling method between simulation platforms such as STAR‐CCM+ and ABAQUS, the SST k‐ω turbulence model is used to obtain the surface pressure and surrounding flow of the VAWT, and the finite element method is used to obtain the dynamic responses of its str…
Muscle Oxygen Delivery in the Forearm and in the Vastus Lateralis Muscles in Response to Resistance Exercise: A Comparison Between Nepalese Porters a…
2020
Altitude ascending represents an intriguing experimental model reproducing physiological and pathophysiological conditions sharing hypoxemia as the denominator. The aim of the present study was to investigate fractional oxygen extraction and blood dynamics in response to hypobaric hypoxia and to acute resistance exercises, taking into account several factors including different ethnic origin and muscle groups. As part of the “Kanchenjunga Exploration & Physiology” project, six Italian trekkers and six Nepalese porters took part in a high altitude trek in the Himalayas. The measurements were carried out at low (1,450 m) and high altitude (HA; 4,780 m). Near-infrared spectroscopy (NIRS)-d…