Delay-independent decentralised output feedback control for large-scale systems with nonlinear interconnections

In this paper, a stabilisation problem for a class of large-scale systems with nonlinear interconnections is considered. All the uncertainties are nonlinear and are subject to the effects of time delay. A decentralised static output feedback variable structure control is synthesised and the stability of the corresponding closed-loop system is analysed based on the Lyapunov Razumikhin approach. A set of conditions is developed to guarantee that the large-scale interconnected system is stabilised uniformly asymptotically. Further study shows that the conservatism can be reduced by employing additive controllers if the known interconnections are separated into matched and mismatched parts. It is not required that the subsystems are square. The designed controller is independent of time delay and thus it does not require memory. Simulation results show the effectiveness of the proposed approach

Fill the void: improved scheduling for optical switching

With ever-increasing demand for bandwidth, optical packet/burst switching is proposed to utilize more of the available capacity of optical networks in the future. In these packet-based switching techniques, packet contention on a single wavelength is resolved effectively by means of Fiber Delay Lines. The involved scheduling algorithms are typically designed to minimize packet loss and/or packet delay. By filling so-called voids, void-filling algorithms are known to outperform their non-void-filling counterparts. This however comes at a large computational cost as the void-filling algorithms have to keep track of beginnings and endings of all voids. This is opposed to the non-void-filling algorithms which only have to keep track of a single system state variable. We therefore propose a new type of algorithm that selectively creates voids that are larger than strictly needed, only when these will likely be filled. Results obtained by Monte Carlo simulation show that selective void creation can jointly reduce packet loss by 50% and packet delay by 18%, without imposing a high computational cost

Mind the gap: void-creating algorithms for optical switching

With ever-increasing demand for bandwidth, optical packet/burst switching is proposed to utilize more of the available capacity of optical networks in the future. In these packet-based switching techniques, packet contention on a single wavelength is resolved effectively by means of Fiber Delay Lines. The involved scheduling algorithms are typically designed to minimize packet loss and/or packet delay. By filling so-called voids, void-filling algorithms are known to outperform their non-void-filling counterparts. This however comes at a large computational cost as the void-filling algorithms have to keep track of beginnings and endings of all voids. This is opposed to the non-void-filling algorithms which only have to keep track of a single system state variable. We therefore propose a new type of algorithm that selectively creates voids that are larger than strictly needed, only when these will likely be filled. Results obtained by Monte Carlo simulation show that selective void creation can jointly reduce packet loss by 50% and packet delay by 18%, without imposing a high computational cost

Simulation on probabilistic anti collision protocols of RFID using variable delay

In RFID System, it is important to avoid tag collision for identifying tag faster. In this paper, we proposed concept of variable delay for tag estimation & identification. The scheme is based on the Multi-level dynamic framed ALOHA protocol. Simulation results indicate that the time delay is added to each tag for avoiding collision. The main advantage of this is the delay is in microseconds which will not create problem of more time consumption

Theoretical study of ionization of an alkali atom adsorbed on a metal surface by laser assisted subfemtosecond pulse

The first numerical simulation of the process of ionization of an atom adsorbed on a metal surface by the subfemtosecond pulse is presented. The streaking scheme is considered, when a weak sub-femtosecond pulse comes together with a strong IR pulse with a variable delay between them. The problem is analyzed with numerical solving the non-stationary Schroedinger equation in the cylindrical coordinate. The results obtained are compared with ones in the gas phase. We show that the surface influences the DDCS, but the observation of this influence, beside the trivial polarization shift of the energy of the initial state, requires a quite high experimental resolution

Stochastic Liouville Equations for Femtosecond Stimulated Raman Spectroscopy

Electron and vibrational dynamics of molecules are commonly studied by subjecting them to two interactions with a fast actinic pulse that prepares them in a nonstationary state and after a variable delay period $T$, probing them with a Raman process induced by a combination of a broadband and a narrowband pulse. This technique known as femtosecond stimulated Raman spectroscopy (FSRS) can effectively probe time resolved vibrational resonances. We show how FSRS signals can be modeled and interpreted using the stochastic Liouville equations (SLE) originally developed for NMR lineshapes. The SLE provides a convenient simulation protocol that can describe complex dynamics due to coupling to collective coordinates at much lower cost that a full dynamical simulation. The origin of the dispersive features which appear when there is no separation of timescales between vibrational variations and dephasing is clarified

Computer aided design and simulation of an intergrated photonic delay line system for phased array antenna and other microve signal processing applications

Over the past few years, phased array antennas and variable RF/Microwave delay lines have been the subject of much research. This thesis presents a photonic solution to the generation of multiple, compact delay lines. Variable time delays are generated by optically tapping points on an acousto-optic cell by the use of a deformable mirror device. Isolation of a particular time delay is accomplished by the conversion of a time delay point into a corresponding spatial frequency by the use of appropriate optics. The desired time delay is recovered by heterodyning a local oscillator with the desired spatial frequency, selected by a tiltable mirror device. Multiple delay lines are produced by the use of a binary optic device. The design and simulation of the integrated optical system was carried out using a real ray tracing program written by the author. Theoretical signal to noise calculations are also carried out