Development of Nuclear Magnetic Resonance Downhole Logging Tool For Hydrocarbones Search

This thesis presents a new development in the design of Nuclear Magnetic Resonance (NMR) downhole logging tools for the oil and gas industry and operates in a high temperature environment. Two main improvements of this tool is suggested and analyzed in this thesis. They are a new NMR antenna containing a Faraday shield placed between the antenna coil and the analyzed fluid and an improved NMR transmitter operating at 175 °C ambient temperature. This is based on multi-module, multilevel topology, which combines the outputs of several identical power modules, which operate at a 50% duty cycle at its fundamental frequency. The NMR antenna equipped with Faraday shield decreases the resonant frequency shift to less than 1%, which makes it possible to perform measurements without engaging a special tuning system for the compensation of antenna detuning. It was shown experimentally that the implementation of the Faraday shield makes the NMR echo signal less dependant on the type of the well fluid being measured. For the multi-module NMR transmitter, a method of DC/AC conversion based on the multi-vector synthesis of the sinusoidal voltage with sequential elimination of the higher harmonics in the output voltage was used. This was done in order to decrease the power dissipation occurring in the resonant loads. The present study reevaluates the prior investigations of a silicon MOSFET’s drain-to-source resistance (Rdson) in a temperature range of up to 200 °C as a function of the temperature and the drain current (Id). An imp-roved Rdson behavioral model in which Rdson and power index (P) of Rdson dependence on the temperature proposed as a function of Id was tested and validated for the temperature range from 25 °C to 200 °C. The multilayer X7R type capacitors, used as the high power NMR transmitter’s filters, were investigated for excessive losses and ways to mitigate these losses were suggested. It was demonstrated that these capacitors behave as piezoelectric resonators when biased with DC voltage and that their mechanical resonances increase the capacitors’ losses and propability of failure. The multimodule NMR transmitter, which uses a combination of the fixed phase shift method for the cancellation of the higher harmonics an increase of the NMR tool signal to noise ratio and NMR transmitter life expectancy. The higher harmonics cancelation in the multimodule NMR transmitter was validated experimentally by testing transmitters with different topologies

Consideraciones acerca de la viabilidad de un sensor plenóptico en dispositivos de consumo

Doctorado en Ingeniería IndustrialPassive distance measurement of the objects in an image gives place to interesting applications that have the potential to revolutionize the field of photography. In this thesis a prototype of plenoptic camera for mobile devices was created and studied. This technique has two main disadvantages: the need for modifying the camera module and the loss of resolution. Because of this, the prototype was discarded in order to utilize another technique: depth from focus. In this technique the capture method consists in taking several images while varying the focus distance. The set of images is called focal-stack. Different focus operators are studied, which give a measure of defocus per pixel and plane of the focal-stack. The curvelet based focus operator is chosen as the most adequate. It is computationally more intensive than other operators but it is capable of decomposing natural images using few coefficients. In order to make viable its usage in mobile devices a new curvelet transform based on the discrete Radon transform is built. The discrete Radon transform has logarithmic complexity, does not use the Fourier transform and uses only integer sums. Lastly, different versions of the Radon transform are analyzed with the goal of achieving an even faster transform. These transforms are implemented to be executed on mobile devices. Additionally, an application of the Radon transform is presented. It consists in the detection of bar-codes that have any orientation in an image.La medida pasiva de distancia a los objetos en una imagen da lugar a interesantes aplicaciones con capacidad para revolucionar la fotografía. En esta tesis se creó y estudió un prototipo de cámara plenóptica para dispositivos móviles. Esta técnica presenta dos inconvenientes: la necesidad de modificar el módulo de cámara y la pérdida de resolución. Por ello, el prototipo fue descartado para utilizar otra técnica: la profundidad a partir del desenfoque. En esta técnica el método de captura consiste en tomar varias imagenes variando la distancia de enfoque. El conjunto de imágenes se denomina focal-stack. Se estudian distintos operadores de desenfoque, que dan una medida de desenfoque por pixel y por plano del focal-stack. Siendo elegido como óptimo el operador de desenfoque curvelet, que es computacionalmente más intensivo que otros operadores pero es capaz de descomponer imagenes naturales utilizando muy pocos coeficientes. Para hacer posible su uso en dispositivos móviles se construye una nueva transformada curvelet basada en la transformada discreta de Radon. La transformada discreta de Radon tiene complejidad linearítmica, no utiliza la transformada de Fourier y usa sólo sumas de enteros. Por último, se analizan distintas versiones de la transformada de Radon con el objetivo de conseguir una transformada aún más rápida y se implementan para ser ejecutadas en dispositivos móviles. Además se presenta una aplicación de la transformada de Radon consistente en la detección de códigos de barras con cualquier orientación en una imagen

Signal Subspace Processing in the Beam Space of a True Time Delay Beamformer Bank

A number of techniques for Radio Frequency (RF) source location for wide bandwidth signals have been described that utilize coherent signal subspace processing, but often suffer from limitations such as the requirement for preliminary source location estimation, the need to apply the technique iteratively, computational expense or others. This dissertation examines a method that performs subspace processing of the data from a bank of true time delay beamformers. The spatial diversity of the beamformer bank alleviates the need for a preliminary estimate while simultaneously reducing the dimensionality of subsequent signal subspace processing resulting in computational efficiency. The pointing direction of the true time delay beams is independent of frequency, which results in a mapping from element space to beam space that is wide bandwidth in nature. This dissertation reviews previous methods, introduces the present method, presents simulation results that demonstrate the assertions, discusses an analysis of performance in relation to the Cramer-Rao Lower Bound (CRLB) with various levels of noise in the system, and discusses computational efficiency. One limitation of the method is that in practice it may be appropriate for systems that can tolerate a limited field of view. The application of Electronic Intelligence is one such application. This application is discussed as one that is appropriate for a method exhibiting high resolution of very wide bandwidth closely spaced sources and often does not require a wide field of view. In relation to system applications, this dissertation also discusses practical employment of the novel method in terms of antenna elements, arrays, platforms, engagement geometries, and other parameters. The true time delay beam space method is shown through modeling and simulation to be capable of resolving closely spaced very wideband sources over a relevant field of view in a single algorithmic pass, requiring no course preliminary estimation, and exhibiting low computational expense superior to many previous wideband coherent integration techniques

Signal Subspace Processing in the Beam Space of a True Time Delay Beamformer Bank

A number of techniques for Radio Frequency (RF) source location for wide bandwidth signals have been described that utilize coherent signal subspace processing, but often suffer from limitations such as the requirement for preliminary source location estimation, the need to apply the technique iteratively, computational expense or others. This dissertation examines a method that performs subspace processing of the data from a bank of true time delay beamformers. The spatial diversity of the beamformer bank alleviates the need for a preliminary estimate while simultaneously reducing the dimensionality of subsequent signal subspace processing resulting in computational efficiency. The pointing direction of the true time delay beams is independent of frequency, which results in a mapping from element space to beam space that is wide bandwidth in nature. This dissertation reviews previous methods, introduces the present method, presents simulation results that demonstrate the assertions, discusses an analysis of performance in relation to the Cramer-Rao Lower Bound (CRLB) with various levels of noise in the system, and discusses computational efficiency. One limitation of the method is that in practice it may be appropriate for systems that can tolerate a limited field of view. The application of Electronic Intelligence is one such application. This application is discussed as one that is appropriate for a method exhibiting high resolution of very wide bandwidth closely spaced sources and often does not require a wide field of view. In relation to system applications, this dissertation also discusses practical employment of the novel method in terms of antenna elements, arrays, platforms, engagement geometries, and other parameters. The true time delay beam space method is shown through modeling and simulation to be capable of resolving closely spaced very wideband sources over a relevant field of view in a single algorithmic pass, requiring no course preliminary estimation, and exhibiting low computational expense superior to many previous wideband coherent integration techniques

The Deep Space Network

Deep Space Network progress in flight project support, tracking and data acquisition, research and technology, network engineering, hardware and software implementation, and operations is cited. Topics covered include: tracking and ground based navigation; spacecraft/ground communication; station control and operations technology; ground communications; and deep space stations

An electronically focused multiple beam side scan sonar

Phased arrays have been in use since World War II but their commercial application has been constrained by the bulk and cost of the beam forming system. High resolution side scan sonar systems have many operational parameters that may only be extended with the aid of phased arrays, the resolution and the imaging rate being the most important. This thesis describes a microprocessor controlled dynamically focused side scan sonar where high resolution and high image acquisition rates are achieved. Dynamic focusing prevents the depth of field limitations of fixed focus arrays by updating the array phases at regular intervals so as to create a focal point which recedes from the array in synchronism with the returning echoes from the transmitted pulse. A high image acquisition rate is achieved through the simultaneous formation of multiple beams. Using a microprocessor as a low-cost controller demands rapidly executable software and a little specialized hardware. Programmable quadrature phase shifters give phase and amplitude control. A beam forming board combines the phase shifted signals into a beam and samples it. A 'time domain multiplexed' transmitter solves the problem of efficient insonification of swaths. The system timing is complex; while image samples are captured data is formatted and presented for recording on a chart recorder. This occurs in real-time, while the focus of each of the multiple beams is changed almost every two meters. Tank tests of the completed system provide confirmation of the resolution predicted with theory and computer simulation. Sea trials confirm that resolution close to that predicted may be obtained under operational circumstances. The results obtained fully justify the assertion that low cost microprocessor controlled dynamically focused multiple beam phased arrays are both an attainable and an attractive solution to the problems faced by the designer of high resolution side scan sonar systems

Portable Ultrasound Imaging

This PhD project investigates hardware strategies and imaging methods for hand-held ultrasound systems. The overall idea is to use a wireless ultrasound probe linked to general-purpose mobile devices for the processing and visualization. The approach has the potential to reduce the upfront costs of the ultrasound system and, consequently, to allow for a wide-scale utilization of diagnostic ultrasound in any medical specialties and out of the radiology department. The first part of the contribution deals with the study of hardware solutions for the reduction of the system complexity. Analog and digital beamforming strategies are simulated from a system-level perspective. The quality of the B-mode image is evaluated and the minimum specifications are derived for the design of a portable probe with integrated electronics in-handle. The system is based on a synthetic aperture sequential beamforming approach that allows to significantly reduce the data rate between the probe and processing unit. The second part investigates the feasibility of vector flow imaging in a hand-held ultrasound system. Vector flow imaging overcomes the limitations of conventional imaging methods in terms of flow angle compensation. Furthermore, high frame rate can be obtained by using synthetic aperture focusing techniques. A method is developed combining synthetic aperture sequential beamforming and directional transverse oscillation to achieve the wireless transmission of the data along with a relatively inexpensive 2-D velocity estimation. The performance of the method is thoroughly assessed through simulations and measurements, and in vivo investigations are carried out to show its potential in presence of complex flow dynamics. A sufficient frame rate is achieved to allow for the visualization of vortices in the carotid bifurcation. Furthermore, the method is implemented on a commercially available tablet to evaluate the real-time processing performance in the built-in GPU with concurrent wireless transmission of the data. Based on the demonstrations in this thesis, a flexible framework can be implemented with performance that can be scaled to the needs of the user and according to the computing resources available. The integration of high-frame-rate vector flow imaging in a hand-held ultrasound scanner, in addition, has the potential to improve the operator’s workflow and opens the way to new possibilities in the clinical practice

Engineering coherent control of quantum information in spin systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.Includes bibliographical references (p. 151-161).Quantum Information Processing (QIP) promises increased efficiency in computation. A key step in QIP is implementing quantum logic gates by engineering the dynamics of a quantum system. This thesis explores the requirements and methods of coherent control in the context of magnetic resonance for: (i) nuclear spins of small molecules in solution and (ii) nuclear and electron spins in single crystals. The power of QIP is compromised in the presence of decoherence. One method of protecting information from collective decoherence is to limit the quantum states to those respecting the symmetry of the noise. These decoherence-free subspaces (DFS) encode one logical quantum bit (qubit) within multiple physical qubits. In many cases, such as nuclear magnetic resonance (NMR), the control Hamiltonians required for gate engineering leak the information outside the DFS, whereby protection is lost: It is shown how one can still perform universal logic among encoded qubits in the presence of leakage. These ideas are demonstrated on four carbon-13 spins of a small molecule in solution. Liquid phase NMR has shortcomings for QIP, like the lack of strong measurement and low polarization. These two problems can be addressed by moving to solid-state spin systems and incorporating electron spins. If the hyperfine interaction has an anisotropic character, it is proven that the composite system of one electron and N nuclear spins (le-Nn) is completely controllable by addressing only to the electron spin. This 'electron spin actuator' allows for faster gates between the nuclear spins than would be achievable in its absence. In addition, a scheme using logical qubit encodings is proposed for removing the added decoherence due to the electron spin. Lastly, this thesis exemplifies arbitrary gate engineering in a le-ln ensemble solid-sate spin system using a home-built ESR spectrometer designed specifically for engineering high-fidelity quantum control.by Jonathan Stuart Hodges.Ph.D

NASA Tech Briefs, April 1990

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