Fault detection using transfer function techniques

SIGLEAvailable from British Library Document Supply Centre- DSC:D75688/87 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Time-Varying System Identification Using Modulating Functions and Spline Models With Application to Bio-Processes

Time dependent parameters are frequently encountered in many real processes which need to be monitored for process modeling, control and supervision purposes. Modulating functions methods are especially suitable for this task because they use the original continuous-time differential equations and avoid differentiation of noisy signals. Among the many versions of the method available, Pearson–Lee method offers a computationally efficient alternative. In this paper, Pearson–Lee method is generalized for non-stationary continuous-time systems and the on-line version is developed. The time dependent parameters are modeled as polynomial splines inside a moving data window and recursion formulae using shifting properties of sinusoids are formulated. The simple matrix update relations considerably reduce the number of computations required when compared with repeatedly using FFT. The method is illustrated for estimating the kinetic rates and yield factors as time-varying parameters in a fermentation process. The Monod law along with temperature dependency models were used to simulate the data. The simulation study shows that it is not necessary to assume a growth model in order to estimate the kinetic rate parameters

Intermodulation distortion from receiver non-linear phase characteristics Final report

Computation of intermodulation distortion levels produced by telemetry system predetection filte

Development of a scanning system for use in the Terahertz region of the Electromagnetic Spectrum

This thesis concerned the development of a scanner system for use in the Terahertz region of the Electromagnetic spectrum. The approach used by the prototype developed, utilises two tilting mirrors for the purposes of scanning a target under investigation. An object is scanned by tilting an incident beam of radiation to a point of interest on the target, on this basis an image can be formed on a point by point basis. The Thesis begins with an Introduction to THz radiation and its associated properties. The need for a Terahertz scanner and the potential applications in the biomedical, security and space research are outlined. The reader is then introduced to various approaches utilised by currently existing scanners and the approach used for the work carried out in this thesis outlined in detail. The techniques used for computationally modelling diffraction limited optical systems are discussed namely Fresnel Diffraction, Gaussian Beam Mode Analysis (GBMA) and Physical Optics. The effectiveness of these techniques are highlighted by using each method to model elementary optical systems. The techniques are then used to computationally model the optical system used for the prototype developed and results presented. The final section is concerned with the development of the prototype including background theory on components used, implementation of the components and verification of alignment procedure. The development of the computer controlled tilting mirror system and its integration with the prototype is also outlined. Finally the results of the operational scanning prototype are presented and discussed

Development of a scanning system for use in the Terahertz region of the Electromagnetic Spectrum

This thesis concerned the development of a scanner system for use in the Terahertz region of the Electromagnetic spectrum. The approach used by the prototype developed, utilises two tilting mirrors for the purposes of scanning a target under investigation. An object is scanned by tilting an incident beam of radiation to a point of interest on the target, on this basis an image can be formed on a point by point basis. The Thesis begins with an Introduction to THz radiation and its associated properties. The need for a Terahertz scanner and the potential applications in the biomedical, security and space research are outlined. The reader is then introduced to various approaches utilised by currently existing scanners and the approach used for the work carried out in this thesis outlined in detail. The techniques used for computationally modelling diffraction limited optical systems are discussed namely Fresnel Diffraction, Gaussian Beam Mode Analysis (GBMA) and Physical Optics. The effectiveness of these techniques are highlighted by using each method to model elementary optical systems. The techniques are then used to computationally model the optical system used for the prototype developed and results presented. The final section is concerned with the development of the prototype including background theory on components used, implementation of the components and verification of alignment procedure. The development of the computer controlled tilting mirror system and its integration with the prototype is also outlined. Finally the results of the operational scanning prototype are presented and discussed

The next generation of interferometry : multi-frequency optical modelling, control concepts and implementation

[no abstract

Design, implementation and characterization of the advanced LIGO 200 W laser system

[no abstract

Adaptive Mode Matching in Advanced LIGO and Beyond

The era of gravitational wave astronomy was ushered in by the LIGO (Laser Interferometer Gravitational-Wave Observatory) collaboration with the detection of a binary black hole collision [2]. The event that shook the foundation of space-time allowed mankind to view the cosmos in a way that had never been done previously. Since then, another remarkable event was found by the LIGO and Virgo detectors where two neutron stars collided, sending both gravitational and electromagnetic waves to earth [3]. LIGO was built with the purpose of detecting the ripples in space-time caused by astrophysical events with the hopes of understanding the complexities hidden within the cosmos. In 2011, the primary stages of Advanced LIGO were installed and commissioned to start the first observing run (O1). During the writing of this thesis, the detectors had hardware replaced in order to mitigate noise from scattered light and new optics which reduced the losses from absorption. The upgrades were in preparation for the third observing run (O3) and the work presented here is primarily focused on experimental techniques for operating at higher power and mode matching Gaussian beams in the dual-recycled Michelson interferometer for the Advanced LIGO era and beyond. The first two chapters discuss the fundamentals of gravitational waves and the LIGO detector configurations. The third chapter introduces the reader to fundamentals in mode matching Gaussian laser beams. The fourth and fifth chapter summarizes the author\u27s work at Syracuse University. The sixth chapter deals with work at the LIGO Hanford observatory with an emphasis on mode sensing and high-power operation

Homodyne detection for laser-interferometric gravitational wave detectors

Gravitational waves are ripples of space-time predicted by Einstein\u27s theory of General Relativity. The Laser Interferometer Gravitational-wave Observatory (LIGO), part of a global network of gravitational wave detectors, seeks to detect these waves and study their sources. The LIGO detectors were upgraded in 2008 with the dual goals of increasing the sensitivity (and likelihood of detection) and proving techniques for Advanced LIGO, a major upgrade currently underway. As part of this upgrade, the signal extraction technique was changed from a heterodyne scheme to a form of homodyne detection called DC readout. The DC readout system includes a new optical filter cavity, the output mode cleaner, which removes unwanted optical fields at the interferometer output port. This work describes the implementation and characterization of the new DC readout system and output mode cleaner, including the achieved sensitivity, noise couplings, and servo control systems