316 research outputs found
Optimization of parameters of asymptotically stable systems
This work deals with numerical methods of parameter optimization for asymptotically stable
systems.We formulate a special mathematical programming problem that allows us to determine
optimal parameters of a stabilizer. This problem involves solutions to a differential equation. We
show how to chose the mesh in order to obtain discrete problem guaranteeing the necessary
accuracy. The developed methodology is illustrated by an example concerning optimization of
parameters for a satellite stabilization system.FCT, QREN, FEDER, COMPET
Physical Signals and their Thermonuclear Astrochemical Potentials: A Review on Outer Space Technologies
The article reviews on the technical attributes on current technologies deployed in outer space and those that are being developed and mass produced. The article refutes the Chinese state-controlled Xinhua News’ propaganda several years ago on objecting America’s deployment of nuclear technologies in outer space with rigorous scientific evidence. Furthermore, the article warns on the dangers of physical signals applied in outer space technologies that can threaten the solar system, especially the Mozi quantum satellite with photon beams. The article concludes with the illicit practices by the Chinese state party with militant ambitions in the supposedly scientific institutions. It violates the spirit on the peaceful use of outer space, and goes against the 2222 (XXI) resolution adopted by the general assembly, including the 1967 Outer Space Treaty banning the stationing of weapons of mass destruction in outer space
Inflation:Generic predictions and nilpotent superfields
Met de observaties van de Planck satelliet begint de kosmologie aan een nieuw tijdperk waarin het universum bestudeerd kan worden met hoge precisie. Dit levert interessante informatie op over het zeer vroege universum, inclusief de inflatieperiode. Deze kosmologische inflatie werd in dit doctoraat op twee manieren theoretisch bestudeerd. Met de eerste methode wordt een groot aantal inflatiemodellen met de data van de CMB, zoals gemeten door de Planck satelliet, met elkaar vergeleken. Hieruit kunnen generieke voorspellingen worden afgeleid voor de verschillende parametrisaties waarmee deze modellen zijn verkregen. Door verschillende parametrisaties van de potentiaal te vergelijken, wordt geconcludeerd dat modellen behorende tot de groep van de plateau inflatiemodellen beter overeenkomen met de CMB dan de zogeheten polynomische modellen. De tweede benadering bestudeert inflatiemodellen in supergravitatie, hetgeen een extensie is van zowel het standaardmodel van de deeltjesfysica als van de algemene relativiteitstheorie door middel van een nieuwe symmetrie genaamd supersymmetrie. In dit onderzoek bestuderen we een bepaalde inbedding van inflatie in supergravitatie en bestuderen we de theoretische consistentie. Daarnaast zijn we in staat om donkere materie, een ander probleem in de kosmologie, te bestuderen. In een deel van de parameterruimte van ons model wordt deze donkere materie verklaard door een deeltje in de supersymmetrische sector. Hierdoor zijn wij in staat om in ons model zowel supersymmetriebreking, inflatie als donkere materie te beschrijven
Longitudinal control effectiveness and entry dynamics of a single-stage-to-orbit vehicle
The classical theory of flight dynamics for airplane longitudinal stability and control analysis was extended to the case of a hypervelocity reentry vehicle. This includes the elements inherent in supersonic and hypersonic flight such as the influence of the Mach number on aerodynamic characteristics, and the effect of the reaction control system and aerodynamic controls on the trim condition through a wide range of speed. Phugoid motion and angle of attack oscillation for typical cases of cruising flight, ballistic entry, and glide entry are investigated. In each case, closed form solutions for the variations in altitude, flight path angle, speed and angle of attack are obtained. The solutions explicitly display the influence of different regions design parameters and trajectory variables on the stability of the motion
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Non-linear discrete-time observer design by sliding mode
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 09/02/2007.Research into observer design for non-linear discrete-time systems has produced many design methods. There is no general design method however and that provides the motivation to search for a new simple and realizable design method. In this thesis, an observer for non-linear discrete-time systems is designed using the sliding mode technique. The equation of the observer error is split into two parts; the first part being a linearized model of the system and the second part an uncertain vector. The sliding mode technique is introduced to eliminate the uncertainty caused by the uncertain vector in the observer error equation. By choosing the sliding surface and the boundary layer, the observer error is attracted to the sliding surface and stays within the sliding manifold. Therefore, the observer error converges to zero. The proposed technique is applied to two cases of observers for nonlinear discrete-time systems. The second case is chosen to be a particular practical system, namely the non-linear discrete-time ball and beam system. The simulations show that the sliding mode technique guarantees the convergence of the observer error for both systems
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