975 resultados para COLLISION STRENGTHS


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Detecting a looming object and its imminent collision is imperative to survival. For most humans, it is a fundamental aspect of daily activities such as driving, road crossing and participating in sport, yet little is known about how the brain both detects and responds to such stimuli. Here we use functional magnetic resonance imaging to assess neural response to looming stimuli in comparison with receding stimuli and motion-controlled static stimuli. We demonstrate for the first time that, in the human, the superior colliculus and the pulvinar nucleus of the thalamus respond to looming in addition to cortical regions associated with motor preparation. We also implicate the anterior insula in making timing computations for collision events.

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In this paper, a forward-looking infrared (FLIR) video surveillance system is presented for collision avoidance of moving ships to bridge piers. An image preprocessing algorithm is proposed to reduce clutter background by multi-scale fractal analysis, in which the blanket method is used for fractal feature computation. Then, the moving ship detection algorithm is developed from image differentials of the fractal feature in the region of surveillance between regularly interval frames. When the moving ships are detected in region of surveillance, the device for safety alert is triggered. Experimental results have shown that the approach is feasible and effective. It has achieved real-time and reliable alert to avoid collisions of moving ships to bridge piers.

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A new autonomous ship collision free (ASCF) trajectory navigation and control system has been introduced with a new recursive navigation algorithm based on analytic geometry and convex set theory for ship collision free guidance. The underlying assumption is that the geometric information of ship environment is available in the form of a polygon shaped free space, which may be easily generated from a 2D image or plots relating to physical hazards or other constraints such as collision avoidance regulations. The navigation command is given as a heading command sequence based on generating a way point which falls within a small neighborhood of the current position, and the sequence of the way points along the trajectory are guaranteed to lie within a bounded obstacle free region using convex set theory. A neurofuzzy network predictor which in practice uses only observed input/output data generated by on board sensors or external sensors (or a sensor fusion algorithm), based on using rudder deflection angle for the control of ship heading angle, is utilised in the simulation of an ESSO 190000 dwt tanker model to demonstrate the effectiveness of the system.

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This paper provides a solution for predicting moving/moving and moving/static collisions of objects within a virtual environment. Feasible prediction in real-time virtual worlds can be obtained by encompassing moving objects within a sphere and static objects within a convex polygon. Fast solutions are then attainable by describing the movement of objects parametrically in time as a polynomial.

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Semi-empirical weighted oscillator strengths (gf) and lifetimes presented in this work for all experimentally known electric dipole P XII spectral lines and energy levels were computed within a multiconfiguration Hartree-Fock relativistic approach. In this calculation, the electrostatic parameters were optimized by a least-squares procedure in order to improve the adjustment to experimental energy levels. The method produces lifetime and gf values that are in agreement with intensity observations used for the interpretation of spectrograms of solar and laboratory plasmas.

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The southwestern margin of the Eastern Ghats Belt characteristically exposes mafic dykes intruding massif-type charnockites. Dykes of olivine basalt of alkaline composition have characteristic trace element signatures comparable with Ocean Island Basalt (OIB). Most importantly strong positive Nb anomaly and low values of Zr/Nb ratio are consistent with OIB source of the mafic dykes. K-Ar isotopic data indicate two cooling ages at 740 and 530 Ma. The Pan-African thermal event could be related to reactivation of major shear zones and represented by leuco-granite vein along minor shear bands. And 740 Ma cooling age may indicate the low grade metamorphic imprints, noted in some of the dykes. Although no intrusion age could be determined from the present dataset, it could be constrained by some age data of the host charnockite gneiss and Alkaline rocks of the adjacent Prakasam Province. Assuming an intrusion age of similar to 1.3 Ga, Sr-Nd isotopic composition of the dykes indicate that they preserved time-integrated LREE enrichment. In view of the chemical signatures of OIB source, the mafic dykes could as well be related to continental rifting, around 1.3 Ga, which may have been initiated by intra-plate volcanism.

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A sample of 917 children, aged 7 to 17 years, their parents, and their teachers each completed the appropriate version of the Strengths and Difficulties Questionnaire (SDQ), and 120 from each group did so again 2 weeks later. The results indicate that the SDQ demonstrates sound interinformant and test-retest reliability. Younger children, whose self-reports have not been assessed in previous studies, were reliable in their responding, although not as reliable as older children by these measures. However, the internal reliability of the various subscales, in particular, the peer problems subscale, is questionable for both older and younger child respondents. Overall the findings suggest that the SDQ's use may be extended cautiously to include self-report from younger children.

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The purpose of this study was to establish Australian norms for the Strengths and Difficulties Questionnaire (SDQ), a recently developed screening instrument for child and adolescent mental health problems. A random sample consisting of 910 children aged 7-17 years recruited through government schools across Victoria, their parents and their teachers completed the appropriate version of the SDQ. The sample contained the expected spread of normal and abnormal scores according to the UK norms for the SDQ. As previous analyses have suggested that scores on the five subscales and the total difficulties scale of the SDQ may very with age and gender, separate norms for each of the three informant versions, by age and gender are presented in tabular form for children aged 7-17 years.

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As increased work demands and longer working hours become the reality for many employees, the concept of work-life balance has received increasing attention. This paper presents findings from an exploratory study of Australian middle managers, which investigated the impact of middle managers’ daily organisational experiences on their lives both in and beyond the workplace. We focus on respondents’ concerns for the encroachment of work on their personal lives, both through the advent of new technologies and the introduction of flexibility initiatives in the workplace. The unwelcome effects of frustration, stress and fatigue highlight the need for organisations to gain a better understanding of employees’ experiences related to work-life balance.

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The Strengths and Difficulties Questionnaire (SDQ) has been widely adopted as a measure of child and adolescent mental health and behavioral problems. However, despite an impressive number of studies demonstrating its psychometric properties, appropriate analyses of the instrument's underlying structure have not been reported. We conducted confirmatory factor analyses on matched data obtained from a large community sample of 7-17-year-olds, their parents, and their teachers. The analyses indicated that the reputed factor structure was not supported, with none of the subscales being unidimensional. Further, each informant group appeared to respond differently to the questionnaire. Considering the findings in relation to the stringency of the tests used to evaluate the SDQ, its utility, and previous research on its clinical validity, it is suggested that the SDQ be used with caution and in conjunction with other forms of assessment.