9,693 research outputs found

    Mass influx obtained from low-light-level television observations of faint meteors

    Get PDF
    Low light level television systems offer the ability to observe meteors as faint as 10th magnitude which allows the extension of optical meteor data to masses as small as 0.0001 gram. The results of these observations, using image orthicons and intensified vidicons, are presented along with an interpretation in terms of mass flux. This interpretation includes the development of a relationship between peak luminosity of a meteor and mass, velocity, and zenith angle that was derived from single body meteor theory and compares favorably with results obtained from the artificial meteor program. Also included in the mass flux interpretation is an analysis of the observation response of a LLLTV system to fixed and moving point sources

    Vibration characteristics of Z-ring-stiffened 60 deg conical shell models of a planetary entry spacecraft

    Get PDF
    An experimental investigation of the vibration characteristics of a 60 deg conical shell model of a planetary entry vehicle is described and the results presented. Model configurations include the shell with or without one or two Z-ring stiffeners and with or without a simulated payload. Tests were conducted with the model clamped at the small diameter and with the model suspended at the simulated payload. Additionally, calculated results obtained from application of several analytical procedures reported in the literature are presented together with comparisons between experimental and calculated frequencies and meridional mode shapes. Generally, very good frequency agreement between experimental and calculated results was obtained for all model configurations. For small values of circumferential mode number, however, the frequency agreement decreased as the number of ring stiffeners increased. Overall agreement between experimental and calculated mode shapes was generally good. The calculated modes usually showed much larger curvatures in the vicinity of the rings than were observed in the experimentally measured mode shapes. Dual resonances associated with modal preference were noted for the shell without Z-ring stiffeners, whereas the addition of stiffeners produced resonances for which the model responded in two or more modes over different sections of the shell length

    The influence of expertise on brain activation of the action observation network during anticipation of tennis and volleyball serves

    Get PDF
    In many daily activities, and especially in sport, it is necessary to predict the effects of others' actions in order to initiate appropriate responses. Recently, researchers have suggested that the action-observation network (AON) including the cerebellum plays an essential role during such anticipation, particularly in sport expert performers. In the present study, we examined the influence of task-specific expertise on the AON by investigating differences between two expert groups trained in different sports while anticipating action effects. Altogether, 15 tennis and 16 volleyball experts anticipated the direction of observed tennis and volleyball serves while undergoing functional magnetic resonance imaging (fMRI). The expert group in each sport acted as novice controls in the other sport with which they had only little experience. When contrasting anticipation in both expertise conditions with the corresponding untrained sport, a stronger activation of AON areas (SPL, SMA), and particularly of cerebellar structures, was observed. Furthermore, the neural activation within the cerebellum and the SPL was linearly correlated with participant's anticipation performance, irrespective of the specific expertise. For the SPL, this relationship also holds when an expert performs a domain-specific anticipation task. Notably, the stronger activation of the cerebellum as well as of the SMA and the SPL in the expertise conditions suggests that experts rely on their more fine-tuned perceptual-motor representations that have improved during years of training when anticipating the effects of others' actions in their preferred sport. The association of activation within the SPL and the cerebellum with the task achievement suggests that these areas are the predominant brain sites involved in fast motor predictions. The SPL reflects the processing of domain-specific contextual information and the cerebellum the usage of a predictive internal model to solve the anticipation task. © 2014 Balser, Lorey, Pilgramm, Naumann, Kindermann, Stark, Zentgraf, Williams and Munzert

    Determination of the top quark mass from the t¯t cross section measured by CMS at √s = 7TeV

    Get PDF
    Higher-order QCD predictions are used to extract the top quark mass, both in the pole and in the MS scheme, from the top quark pair production cross section measured in the dilepton final state. The analyzed dataset corresponds to an integrated luminosity of 1.14 fb−1 collected by the CMS experiment in 2011 in pp collisions at √s = 7TeV

    Tropical free-tropospheric humidity differences and their effect on the clear-sky radiation budget in global strom-resolving models

    Get PDF
    Reducing the model spread in free-tropospheric relative humidity (RH) and its response to warming is a crucial step toward reducing the uncertainty in clear-sky climate sensitivity, a step that is hoped to be taken with recently developed global storm-resolving models (GSRMs). In this study we quantify the inter-model differences in tropical present-day RH across GSRMs, making use of DYAMOND, a first 40-day intercomparison. We find that the inter-model spread in tropical mean free-tropospheric RH is reduced compared to conventional atmospheric models, except from the tropopause region and the transition to the boundary layer. We estimate the reduction to ∼50%–70% in the upper troposphere and 25%–50% in the mid troposphere. However, the remaining RH differences still result in a spread of 1.2 urn:x-wiley:19422466:media:jame21474:jame21474-math-0001 in tropical mean clear-sky outgoing longwave radiation (OLR). This spread is mainly caused by RH differences in the lower and mid free troposphere, whereas RH differences in the upper troposphere have a minor impact. By examining model differences in moisture space we identify two regimes with a particularly large contribution to the spread in tropical mean clear-sky OLR: rather moist regimes at the transition from deep convective to subsidence regimes and very dry subsidence regimes. Particularly for these regimes a better understanding of the processes controlling the RH biases is needed

    Runoff properties of extreme discharges on Parana and Uruguay rivers

    Get PDF
    Climate variability in different spatial scales is a study area which has reached interest in application, especially during de last years. River discharges can be considered as a robust integrator of the properties of the basin; under these premises the goal of this work is to analyse flows from the Parana and Uruguay rivers in several gauge stations ´ and study the behavior of positive and negative anomalies and their extremes. The variable to be analysed was defined as the number of anomalies with the same sign per year. Results show that the structures are different for both rivers, which implies a different stochastic process. Identical representativeness was found between the anomaly series in each river. The risk estimation of extremes in both rivers indicates that it is possible to establish a decision model. Additionally, the series of annual number of anomalies presented a climatic jump in the seventies, for both rivers.Fil: Vargas, Walter Mario. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bischoff, S.. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; ArgentinaFil: Naumann, Gustavo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Marcuzzi, E.. Plan Nacional de Manejo del Fuego; Argentin

    Mynewhome.com.au : exploring new ways of delivering architecture : creating a design interface for sustainable and affordable houses

    Get PDF
    The aim of this research project was to explore new ways of delivering architecture and the engagement of architects in everyday, affordable, sustainable housing in Australia. This dissertation speculates on the possibility of a design system integrated with a design interface, where customers can self-configure or customise their home online with the help of embedded programs and an architect consultancy service. This can be seen as an alternative option for the homebuyer to the volume built, standard house. The design system displayed in this masters research was developed in three testing modes: speculative designs, site specific designs and user experiments. The system consists of modules and components that would have the embedded knowledge of the architect. They are intended to allow non professionals to self-arrange their homes. This was then integrated into a user interface. A construction system which allows prefabrication was then applied, but the main focus of the research was on the delivery of design and client engagement and not on the technicalities, or the realisation of a prefab system. The aim was to combine as much of the quality and advantages of a one off architecturally designed house, in particular, the consideration of user and site needs with the affordability and predictability of a completely pre-designed volume builder house. Digital design, production and marketing have the potential to make this challenge a success. This new digital way of delivering architecture could lead to houses that are more adaptable to different users and site needs than volume builder housing. The knowledge of the architect could be applied to ordinary housing, without the huge financial cost of the one off, architect designed house. The web based interface would allow customer interaction as tested in user experiments. The internet widens the possibility of the clients' involvement in the design process. These new online procurement processes are more instant and accessible and could result in an enlightened purchaser. There is the possibility to educate people, so informed decisions could be made. It could lead to houses with better orientation, engagement with new building materials, prefabrication technologies and the promotion of smaller houses resulting in more sustainable homes that are still reasonable in price. This is a very complex issue in which different experts would have to work together. However, there is a real possibility for a design interface to open up a dialogue between the architect and the general public
    corecore