26,335 research outputs found
Controllability and stabilizability of distributed bilinear systems: Recent results and open problems
This paper describes recent results for controlling and stabilizing control systems of the form ú(t) = Au(t) + p(t) B(u(t)) where A is the infinitesimal generator C∞ semigroup
on a Banach space X, B' map from X into X, and p(t) is a real valued control. Application to a vibrating beam problem is given for illusstration of the theory
Controllability for Distributed Bilinear Systems
This paper studies controllability of systems of the form where is the infinitesimal generator of a semigroup of bounded linear operators on a Banach space , is a map, and is a control. The paper (i) gives conditions for elements of to be accessible from a given initial state and (ii) shows that controllability to a full neighborhood in of is impossible for . Examples of hyperbolic partial differential equations are provided
A Summary of the Pioneer 10 Maneuver Strategy
The Pioneer Project placed a number of interesting and precise requirements on the navigation of the Pioneer 10 spacecraft flyby mission to Jupiter during 1972-1973. To satisfy these requirements the Pioneer navigation team employed a number of versatile computer programs to evaluate the strategies and maneuver sequences required to execute midcourse corrections. The Pioneer 10 mission objectives and the midcourse strategies used to satisfy these objectives are summarized
Quantum Walks with Entangled Coins
We present a mathematical formalism for the description of unrestricted
quantum walks with entangled coins and one walker. The numerical behaviour of
such walks is examined when using a Bell state as the initial coin state, two
different coin operators, two different shift operators, and one walker. We
compare and contrast the performance of these quantum walks with that of a
classical random walk consisting of one walker and two maximally correlated
coins as well as quantum walks with coins sharing different degrees of
entanglement.
We illustrate that the behaviour of our walk with entangled coins can be very
different in comparison to the usual quantum walk with a single coin. We also
demonstrate that simply by changing the shift operator, we can generate widely
different distributions. We also compare the behaviour of quantum walks with
maximally entangled coins with that of quantum walks with non-entangled coins.
Finally, we show that the use of different shift operators on 2 and 3 qubit
coins leads to different position probability distributions in 1 and 2
dimensional graphs.Comment: Two new sections and several changes from referees' comments. 12
pages and 12 (colour) figure
Variable frequency microwave (VFM) processing facilities and application in processing thermoplastic matrix composites
Microwave processing of materials is a relatively new technology advancement alternative that provides new approaches for enhancing material properties as well as economic advantages through energy savings and accelerated product development. Factors that hinder the use of microwaves in materials processing are declining, so that prospect for the development of this technology seem to be very promising. The two mechanisms of orientation polarisation and interfacial space charge polarisation, together with dc conductivity, form the basis of high frequency heating. Clearly, advantages in utilising microwave technologies for processing materials include penetration radiation, controlled electric field distribution and selective and volumetric heating. However, the most commonly used facilities for microwave processing materials are of fixed frequency, e.g. 2.45 GHz. This paper presents a state-of-the-art review of microwave technologies, processing methods and industrial applications, using variable frequency microwave (VFM) facilities. This is a new alternative for microwave processing
Current research in cavitating fluid films
A review of the current research of cavitation in fluid films is presented. Phenomena and experimental observations include gaseous cavitation, vapor cavitation, and gas entrainment. Cavitation in flooded, starved, and dynamically loaded journal bearings, as well as squeeze films are reviewed. Observations of cavitation damage in bearings and the possibility of cavitation between parallel plates with microasperities were discussed. The transcavity fluid transport process, meniscus motion and geometry or form of the film during rupture, and reformation were summarized. Performance effects were related to heat transfer models in the cavitated region and hysteresis influence on rotor dynamics coefficients. A number of cavitation algorithms was presented together with solution procedures using the finite difference and finite element methods. Although Newtonian fluids were assumed in most of the discussions, the effect of non-Newtonian fluids on cavitation was also discussed
- …