928 resultados para Passive revolution
Resumo:
A year of satellite-borne lidar CALIOP data is analyzed and statistics on occurrence and distribution of bulk properties of cirri are provided. The relationship between environmental and cloud physical parameters and the shape of the backscatter profile (BSP) is investigated. It is found that CALIOP BSP is mainly affected by cloud geometrical thickness while only minor impacts can be attributed to other quantities such as optical depth or temperature. To fit mean BSPs as functions of geometrical thickness and position within the cloud layer, polynomial functions are provided. It is demonstrated that, under realistic hypotheses, the mean BSP is linearly proportional to the IWC profile. The IWC parameterization is included into the RT-RET retrieval algorithm, that is exploited to analyze infrared radiance measurements in presence of cirrus clouds during the ECOWAR field campaign. Retrieved microphysical and optical properties of the observed cloud are used as input parameters in a forward RT simulation run over the 100-1100 cm-1 spectral interval and compared with interferometric data to test the ability of the current single scattering properties database of ice crystal to reproduce realistic optical features. Finally a global scale investigation of cirrus clouds is performed by developing a collocation algorithm that exploits satellite data from multiple sensors (AIRS, CALIOP, MODIS). The resulting data set is utilized to test a new infrared hyperspectral retrieval algorithm. Retrieval products are compared to data and in particular the cloud top height (CTH) product is considered for this purpose. A better agreement of the retrieval with the CALIOP CTH than MODIS is found, even if some cases of underestimation and overestimation are observed.
Resumo:
The dynamics of a passive back-to-back test rig have been characterised, leading to a multi-coordinate approach for the analysis of arbitrary test configurations. Universal joints have been introduced into a typical pre-loaded back-to-back system in order to produce an oscillating torsional moment in a test specimen. Two different arrangements have been investigated using a frequency-based sub-structuring approach: the receptance method. A numerical model has been developed in accordance with this theory, allowing interconnection of systems with two-coordinates and closed multi-loop schemes. The model calculates the receptance functions and modal and deflected shapes of a general system. Closed form expressions of the following individual elements have been developed: a servomotor, damped continuous shaft and a universal joint. Numerical results for specific cases have been compared with published data in literature and experimental measurements undertaken in the present work. Due to the complexity of the universal joint and its oscillating dynamic effects, a more detailed analysis of this component has been developed. Two models have been presented. The first represents the joint as two inertias connected by a massless cross-piece. The second, derived by the dynamic analysis of a spherical four-link mechanism, considers the contribution of the floating element and its gyroscopic effects. An investigation into non-linear behaviour has led to a time domain model that utilises the Runge-Kutta fourth order method for resolution of the dynamic equations. It has been demonstrated that the torsional receptances of a universal joint, derived using the simple model, result in representation of the joint as an equivalent variable inertia. In order to verify the model, a test rig has been built and experimental validation undertaken. The variable inertia of a universal joint has lead to a novel application of the component as a passive device for the balancing of inertia variations in slider-crank mechanisms.
Resumo:
The monitoring of cognitive functions aims at gaining information about the current cognitive state of the user by decoding brain signals. In recent years, this approach allowed to acquire valuable information about the cognitive aspects regarding the interaction of humans with external world. From this consideration, researchers started to consider passive application of brain–computer interface (BCI) in order to provide a novel input modality for technical systems solely based on brain activity. The objective of this thesis is to demonstrate how the passive Brain Computer Interfaces (BCIs) applications can be used to assess the mental states of the users, in order to improve the human machine interaction. Two main studies has been proposed. The first one allows to investigate whatever the Event Related Potentials (ERPs) morphological variations can be used to predict the users’ mental states (e.g. attentional resources, mental workload) during different reactive BCI tasks (e.g. P300-based BCIs), and if these information can predict the subjects’ performance in performing the tasks. In the second study, a passive BCI system able to online estimate the mental workload of the user by relying on the combination of the EEG and the ECG biosignals has been proposed. The latter study has been performed by simulating an operative scenario, in which the occurrence of errors or lack of performance could have significant consequences. The results showed that the proposed system is able to estimate online the mental workload of the subjects discriminating three different difficulty level of the tasks ensuring a high reliability.
Resumo:
L'interazione in maniera sicura e compliante è una caratteristica sempre più richiesta per i sistemi robotici. La modellazione di sistemi eseguita tramite l'uso di sistemi port-Hamiltoninani permette di comprendere cosa avviene a livello energetico durante l'interazione e aiuta nella progettazinoe di un controllore tale che il comportamento del sistema controllato sia passivo e sicuro durante essa. Ciò sfocia nel cosiddetto Controllore Intrinsicamente Passivo (IPC). Dal momento che questo un controllo impone la rigidezza desiderata al sistema controllato, è possibile, tra le altre cose, replicare il comportamento del dispositivo RCC (Centro Remoto di Complianza) e di migliorarlo in modo tale che durante l'azione di peg-in-hole il buco sia meno sollecitato dal robot.
Resumo:
A new 2-D hydrophone array for ultrasound therapy monitoring is presented, along with a novel algorithm for passive acoustic mapping using a sparse weighted aperture. The array is constructed using existing polyvinylidene fluoride (PVDF) ultrasound sensor technology, and is utilized for its broadband characteristics and its high receive sensitivity. For most 2-D arrays, high-resolution imagery is desired, which requires a large aperture at the cost of a large number of elements. The proposed array's geometry is sparse, with elements only on the boundary of the rectangular aperture. The missing information from the interior is filled in using linear imaging techniques. After receiving acoustic emissions during ultrasound therapy, this algorithm applies an apodization to the sparse aperture to limit side lobes and then reconstructs acoustic activity with high spatiotemporal resolution. Experiments show verification of the theoretical point spread function, and cavitation maps in agar phantoms correspond closely to predicted areas, showing the validity of the array and methodology.
Resumo:
In the early decades of the twentieth century, as Japanese society became engulfed in war and increasing nationalism, the majority of Buddhist leaders and institutions capitulated to the status quo. One notable exception to this trend, however, was the Shinkō Bukkyō Seinen Dōmei (Youth League for Revitalizing Buddhism), founded on 5 April 1931. Led by Nichiren Buddhist layman Seno’o Girō and made up of young social activists who were critical of capitalism, internationalist in outlook, and committed to a pan-sectarian and humanist form of Buddhism that would work for social justice and world peace, the league’s motto was “carry the Buddha on your backs and go out into the streets and villages.” This article analyzes the views of the Youth League for Revitalizing Buddhism as found in the religious writings of Seno’o Girō to situate the movement in its social and philosophical context, and to raise the question of the prospects of “radical Buddhism” in twenty-first century Japan and elsewhere.
Resumo:
Neuroeconomics is a rapidly growing new research discipline aimed at describing the neural substrate of decision-making using incentivized decisions introduced in experimental economics. The novel combination of economic decision theory and neuroscience has the potential to better examine the interactions of social, psychological and neural factors with regard to motivational forces that may underlie psychiatric problems. Game theory will provide psychiatry with computationally principled measures of cognitive dysfunction. Given the relatively high heritability of these measures, they may contribute to improving phenotypic definitions of psychiatric conditions. The game-theoretical concepts of optimal behavior will allow description of psychopathology as deviation from optimal functioning. Neuroeconomists have successfully used normative or near-normative models to interpret the function of neurotransmitters; these models have the potential to significantly improve neurotransmitter theories of psychiatric disorders. This paper will review recent evidence from neuroeconomics and psychiatry in support of applying economic concepts such as risk/uncertainty preference, time preference and social preference to psychiatric research to improve diagnostic classification, prevention and therapy.