The effects of atmospheric turbulence upon flight at low altitude and high speed.

Mode of access: Internet.

Equivalence of physical and perceived speed in binocular rivalry

The relative dominance of gratings engaged in binocular rivalry can be influenced by their surroundings. One striking example occurs when surrounding motion is congruent with one but not the other grating (C. L. Paffen, S. F. te Pas, R. Kanai, M. J. van der Smagt, & F. A. Verstraten, 2004). However, such center-surround stimulus configurations can also modulate perceived speed, via a directionally tuned process (H. P. Norman, J. F. Norman, J. T. Todd, & D. T. Lindsey, 1996). We recorded rivalry for Gabor patches embedded in a drifting noise texture. Gratings whose directions opposed the background motion tended to dominate more, and vice versa, consistent with previous findings. Observers then matched the speed of a drifting noise-embedded Gabor to that of a Gabor surrounded by mean luminance. Surround motion produced substantial changes in perceived speed, by at least a factor of two for all observers. We then asked whether perceived speed could account for the contextual effects on dominance. We measured the effects of speed on rivalry dominance by changing the physical speeds of rivaling gratings, as determined by the matching data. We found the same pattern of dominance as for the context experiment, indicating that perceived and true speed influence rivalry in the same manner. We propose a Bayesian interpretation of the perceived speed illusion.

Inward investment, industry concentration and the speed of adjustment

T his paper seeks to examine the relationship between foreign direct investment (FDI) and industry concentration. Previous work in the area is somewhat contradictory in terms of the effect that FDI may be expected to have on host-country market structure. In addition, work which seeks to use concentration as a determinant of FDI (or indeed entry in a more generic sense) is rather ambiguous. This paper seeks to resolve these issues, and argues that inward FDI is more likely to reduce concentration by increasing competition than it is to increase monopoly power. In addition, the paper will show that the role of concentration in explaining FDI is more complex than has previously been understood. This paper is constructed as follows: Section II discusses the hypothesized relationship between market concentration and FDI, while Sections III, IV and V develop the models employed and discuss the econometric issues. Finally Sections VI and VII discuss the results and present some conclusions.

Independent detectors for expansion and rotation, and for orthogonal components of deformation

It is well known that optic flow - the smooth transformation of the retinal image experienced by a moving observer - contains valuable information about the three-dimensional layout of the environment. From psychophysical and neurophysiological experiments, specialised mechanisms responsive to components of optic flow (sometimes called complex motion) such as expansion and rotation have been inferred. However, it remains unclear (a) whether the visual system has mechanisms for processing the component of deformation and (b) whether there are multiple mechanisms that function independently from each other. Here, we investigate these issues using random-dot patterns and a forced-choice subthreshold summation technique. In experiment 1, we manipulated the size of a test region that was permitted to contain signal and found substantial spatial summation for signal components of translation, expansion, rotation, and deformation embedded in noise. In experiment 2, little or no summation was found for the superposition of orthogonal pairs of complex motion patterns (eg expansion and rotation), consistent with probability summation between pairs of independent detectors. Our results suggest that optic-flow components are detected by mechanisms that are specialised for particular patterns of complex motion.

The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds’ Search Performance in Spatial Rotation Tasks

Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N D 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children.

Taajuusmuuttajat voimalaitosten pumppauksissa, erityisesti syöttöveden pyörimisnopeussäädön vaikutus ruiskutusvesijärjestelmiin

Työn ensimmäisessä osassa tutustutaan pumppauksen teoriaan ja esitellään kuristus- ja pyörimisnopeussäätö. Toisessa osassa perehdytään pyörimisnopeussäädössä käytettävän taajuusmuuttajan rakenteeseen ja sen eri osissa syntyviin häviöihin. Kolmannessa osassa tutkitaan kolmen eri tavoin säädetyn pumppauksen toimintaa Pelloksen voimalaitoksella. Lauhdepumpun kierrosnopeussäätöä verrataan vaihtoehtoiseen kuristussäätöön. Viimeisessä osassa selvitetään mahdollisuutta poistaa pyörimisnopeussäädön turhaksi tekemä syöttövesiventtiili voimalaitosten suunnittelusta. Erityisesti etsitään vaihtoehtoisia menetelmiä ruiskutusveden tuottamiseen. Uusia vaihtoehtoja ruiskutusvedelle esitetään kaksitoista. Ruiskutusvesitekniikoita vertaillaan keskenään ja parasta vaihtoehtoa verrataan nykyiseen menettelyyn.

Obtenção de filmes finos de TiO2 nanoestruturado pelo método dos precursores poliméricos

This work focuses in optimizing setup for obtaining TiO2 thin films by polymeric precursor route due to its advantages on stoichiometric and morphological control. Precursor stoichiometry, synthesis pH, solids concentration and rotation speed at deposition were optimized evaluating thin films morphology and thickness. Thermogravimetry and RMN were applied for precursor's characterization and AFM, XRD and ellipsometry for thin films evaluation. Results showed successful attainment of homogeneous nanocrystalline anatase TiO2 thin films with outstanding control over morphological characteristics, mean grain size of 17 nm, packing densities between 57 and 75%, estimated surface areas of 90 m²/g and monolayers thickness within 20 and 128 nm.

Obtenção de filmes finos de TiO2 nanoestruturado pelo método dos precursores poliméricos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Misturador para análise de propriedades reológicas

This study aimed to evaluate the use of a mixer to determine the rheological properties of fluids. The mixer is comprised of an agitation tank and an anchor type impeller. The tests were performed with honey and fruit juices (orange, guava and peach). The rheological characterization was performed using data from the torque and rotation speed required for the operation of fluid agitation. Tests were also made with a concentric cylinder rotational viscometer with the samples being subjected to various shear rates. The rheological parameters were obtained from the flow curves fitted to the power law model. Analyses of results showed that the mixer can be used, within its limitations, to determine rheological properties.

Escrubagem da bauxita de Paragominas - PA. Parte 1: influência de variáveis operacionais na desagregação da bauxita

The aim of this study was to investigate the bauxite scrubbing process on samples from Miltonia 3, a Vale operation in the State of Para, Brazil. The experimental program included the design of a standard laboratory test, from which parameters were derived for predicting the operation of a scrubber in steady state conditions. Three main variables were selected for the laboratory experimental program using the factorial design technique. These were load fraction, residence time and rotation speed. The amount of fines was determined through screening both the feed and the product of the scrubbing test. The former was considered to be a characteristic material, while the second was the dependent variable, i.e. the result of the scrubbing process. According to experiments, the load fraction was the most important variable for the scrubbing process.

Design of axial-flux permanent-magnet low-speed machines and performance comparison between radial-flux and axial-flux machines

This thesis presents an alternative approach to the analytical design of surface-mounted axialflux permanent-magnet machines. Emphasis has been placed on the design of axial-flux machines with a one-rotor-two-stators configuration. The design model developed in this study incorporates facilities to include both the electromagnetic design and thermal design of the machine as well as to take into consideration the complexity of the permanent-magnet shapes, which is a typical requirement for the design of high-performance permanent-magnet motors. A prototype machine with rated 5 kW output power at 300 min-1 rotation speed has been designed and constructed for the purposesof ascertaining the results obtained from the analytical design model. A comparative study of low-speed axial-flux and low-speed radial-flux permanent-magnet machines is presented. The comparative study concentrates on 55 kW machines with rotation speeds 150 min-1, 300 min-1 and 600 min-1 and is based on calculated designs. A novel comparison method is introduced. The method takes into account the mechanical constraints of the machine and enables comparison of the designed machines, with respect to the volume, efficiency and cost aspects of each machine. It is shown that an axial-flux permanent-magnet machine with one-rotor-two-stators configuration has generally a weaker efficiency than a radial-flux permanent-magnet machine if for all designs the same electric loading, air-gap flux density and current density have been applied. On the other hand, axial-flux machines are usually smaller in volume, especially when compared to radial-flux machines for which the length ratio (axial length of stator stack vs. air-gap diameter)is below 0.5. The comparison results show also that radial-flux machines with alow number of pole pairs, p < 4, outperform the corresponding axial-flux machines.

Mathematical modeling of electro-rotation spectra of small particles in liquid solutions: Application to human erythrocyte aggregates

Electro-rotation can be used to determine the dielectric properties of cells, as well as to observe dynamic changes in both dielectric and morphological properties. Suspended biological cells and particles respond to alternating-field polarization by moving, deforming or rotating. While in linearly polarized alternating fields the particles are oriented along their axis of highest polarizability, in circularly polarized fields the axis of lowest polarizability aligns perpendicular to the plane of field rotation. Ellipsoidal models for cells are frequently applied, which include, beside sphere-shaped cells, also the limiting cases of rods and disks. Human erythrocyte cells, due to their particular shape, hardly resemble an ellipsoid. The additional effect of rouleaux formation with different numbers of aggregations suggests a model of circular cylinders of variable length. In the present study, the induced dipole moment of short cylinders was calculated and applied to rouleaux of human erythrocytes, which move freely in a suspending conductive medium under the effect of a rotating external field. Electro-rotation torque spectra are calculated for such aggregations of different length. Both the maximum rotation speeds and the peak frequencies of the torque are found to depend clearly on the size of the rouleaux. While the rotation speed grows with rouleaux length, the field frequency nup is lowest for the largest cell aggregations where the torque shows a maximum.