11,983 research outputs found
Measurements on fully wetted and ventilated ring wing hydrofoils
Force measurements and visual observations were made in a water tunnel on fully wetted and ventilated flows past a family of conical ring wings having a flat plate section geometry. The diameter-chord ratio was varied from one to three, and the total included cone angle was 12 degrees. The fully wetted flows all exhibited separation from the leading edge except for the largest diameter-chord ratio, a result which was in agreement with previous work. The effect of ventilation is to reduce markedly the lift curve slope. Pressure distribution measurements were also made under ventilating conditions for one member of this series. The effect of ventilation over only a portion of the circumference of the ring was also briefly investigated. Large cross forces were developed by such ventilation and some comparisons are made between this method of obtaining control forces and more conventional methods
On signals of new physics in global event properties in pp collisions in the TeV energy domain
In the framework of the weighted superposition mechanism of different classes
of minimum bias events (or substructures), described by the negative binomial
multiplicity distribution, in possible scenarios for pp collisions in the TeV
energy domain, we explore global properties of an eventual new class of events,
characterised by high hadron and clan densities, to be added to the soft
(without minijets) and semihard (with minijets) ones. It turns out that the
main signal of the mentioned new physical expectations at 14 TeV c.m. energy
would be an ``elbow structure'' in the tail of the total charged particle
multiplicity distribution in complete disagreement with the second shoulder
structure predicted by Pythia Monte Carlo calculations: a challenging problem
for new experimental work.Comment: 14 pages, 6 ps figures include
On the Effect of Cavitation on the Radial Forces and Hydrodynamic Stiffness of a Centrifugal Pump
The asymmetric flow within a volute exerts a radial force on a centrifugal impeller. The present paper presents experimental measurements of the radial forces on the impeller in the presence of cavitation
Compensation of relector antenna surface distortion using an array feed
The dimensional stability of the surface of a large reflector antenna is important when high gain or low sidelobe performance is desired. If the surface is distorted due to thermal or structural reasons, antenna performance can be improved through the use of an array feed. The design of the array feed and its relation to the surface distortion are examined. The sensitivity of antenna performance to changing surface parameters for fixed feed array geometries is also studied. This allows determination of the limits of usefulness for feed array compensation
Rotordynamic Forces on Centrifugal Pump Impellers
The asymmetric flow around an impeller in a volute exerts a force upon the impeller. To study the rotordynamic force on an impeller which is vibrating around its machine axis of rotation, the impeller, mounted on a dynamometer, is made to whirl in a circular orbit within the volute. The measured force is expressed as the sum of a steady radial force and an unsteady force due to the eccentric motion of the impeller. These forces were measured in separate tests on a centrifugal pump with radically increased shroud clearance, a two-dimensional impeller, and an impeller with an inducer, the impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Enginer). In each case, a destabilizing force was observed over a region of positive whirl
Uso do sistema integrado de análise e recomendação (DRIS) para quatro nutrientes na cultura do milho em áreas demonstrativas no Noroeste do Rio Grande do Sul.
Periodic Chaotic Billiards: Quantum-Classical Correspondence in Energy Space
We investigate the properties of eigenstates and local density of states
(LDOS) for a periodic 2D rippled billiard, focusing on their quantum-classical
correspondence in energy representation. To construct the classical
counterparts of LDOS and the structure of eigenstates (SES), the effects of the
boundary are first incorporated (via a canonical transformation) into an
effective potential, rendering the one-particle motion in the 2D rippled
billiard equivalent to that of two-interacting particles in 1D geometry. We
show that classical counterparts of SES and LDOS in the case of strong chaotic
motion reveal quite a good correspondence with the quantum quantities. We also
show that the main features of the SES and LDOS can be explained in terms of
the underlying classical dynamics, in particular of certain periodic orbits. On
the other hand, statistical properties of eigenstates and LDOS turn out to be
different from those prescribed by random matrix theory. We discuss the quantum
effects responsible for the non-ergodic character of the eigenstates and
individual LDOS that seem to be generic for this type of billiards with a large
number of transverse channels.Comment: 13 pages, 18 figure
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