75,280 research outputs found
Axisymmetric stability criterion for two gravitationally coupled singular isothermal discs
Using the two-fluid formalism with the polytropic approximation, we examine
the axisymmetric stability criterion for a composite system of gravitationally
coupled stellar and gaseous singular isothermal discs (SIDs).Comment: 12 pages, 11 figures, accepted by MNRA
On the Implementation of AM/AM AM/PM Behavioral Models in System Level Simulation
The use of nonlinear device behavioral models offers an economical way of simulating the performance of complex communication systems. A concrete method for implementing the AM/AM AM/PM behavioral model in system level simulation using ADS is developed. This method seamlessly tansfers the data from the circuit level simulation to system level simulation, where the AM/AM AM/PM model is automatically built. The methodology is extendible for use in other software packages or between different software packages
Cavitation Scaling Experiments With Headforms: Bubble Acoustics
Recently Ceccio and Brennen [1][2][3] have
examined the interaction between individual traveling
cavitation bubbles and the structure of the boundary layer
and flow field in which the bubble is growing and
collapsing. They were able to show that individual
bubbles are often fissioned by the fluid shear and that this
process can significantly effect the acoustic signal
produced by the collapse. Furthermore they were able to
demonstrate a relationship between the number of
cavitation events and the nuclei number distribution
measured by holographic methods in the upstream flow.
Kumar and Brennen [4][5] have further examined the
statistical properties of the acoustical signals from
individual cavitation bubbles on two different headforms
in order to learn more about the bubble/flow interactions.
All of these experiments were, however, conducted in the
same facility with the same size of headform (5.08cm in
diameter) and over a fairly narrow range of flow
velocities (around 9m/s). Clearly this raises the issue of
how the phenomena identified change with speed, scale
and facility. The present paper will describe further
results from experiments conducted in order to try to
answer some of these important questions regarding the
scaling of the cavitation phenomena. These experiments
(see also Kuhn de Chizelle et al. [6][7]) were conducted
in the Large Cavitation Channel of the David Taylor
Research Center in Memphis Tennessee, on similar
Schiebe headforms which are 5.08, 25.4 and 50.8cm in
diameter for speeds ranging up to 15m/s and for a range
of cavitation numbers
Engineering the accurate distortion of an object's temperature-distribution signature
It is up to now a challenge to control the conduction of heat. Here we
develop a method to distort the temperature distribution signature of an object
at will. As a result, the object accurately exhibits the same temperature
distribution signature as another object that is predetermined, but actually
does not exist in the system. Our finite element simulations confirm the
desired effect for different objects with various geometries and compositions.
The underlying mechanism lies in the effects of thermal metamaterials designed
by using this method. Our work is of value for applications in thermal
engineering.Comment: 11 pages, 4 figure
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