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Albannay, Mohammed Masoud. "Array of antenna arrays." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/75576/1/Mohammed_Albannay_Thesis.pdf.
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Antenna arrays are groups of antenna elements spaced in a geometrical pattern. By changing the phase excitation of each element, the array is capable of transmitting electromagnetic waves strongly in a chosen direction with little or no radiation in another direction, thus controlling the array's radiation pattern without physically moving any parts. An antenna array of sub-arrays replaces conventional antenna elements with compact circular arrays with potential for improved performance.
This thesis expands on the concept by exploring the development, realisation and operation of an array of subarrays. The overall size of the array essentially remains the same, but the array's performance is improved due to having steerable directive subarrays. The negative effects of strong mutual coupling between closely spaced elements of a subarray are analysed and a number of new solutions for element decoupling are proposed.
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Tzanidis, Ioannis. "Ultrawideband Low-Profile Arrays of Tightly Coupled Antenna Elements: Excitation, Termination and Feeding Methods." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316439948.
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Alsawaha, Hamad Waled. "Synthesis of Ultra-Wideband Array Antennas." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/54553.
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Acquisition of ultra-wideband signals by means of array antennas requires essentially frequency-independent radiation characteristics over the entire bandwidth of the signal in order to avoid distortions. Factors contributing to bandwidth limitation of arrays include array factor, radiation characteristics of the array element, and inter-element mutual coupling. Strictly speaking, distortion-free transmission or reception of ultra-wideband signals can be maintained if the magnitude of the radiated field of the array remains constant while its phase varies linearly with frequency over the bandwidth of interest. The existing wideband-array synthesis methods do not account for all factors affecting the array bandwidth and are often limited to considering the array factor and not the total field of the array in the synthesis process.
The goal of this study is to present an ultra-wideband array synthesis technique taking into account all frequency-dependent properties, including array total pattern, phase of the total radiated field, element field, element input impedance, and inter-element mutual coupling. The proposed array synthesis technique is based on the utilization of frequency-adaptive element excitations in conjunction with expressing the total radiated field of the array as a complex Fourier series. Using the proposed method, element excitation currents required for achieving a desired radiation pattern, while compensating for frequency variations of the element radiation characteristics and the inter-element mutual coupling, are calculated.
An important consideration in the proposed ultra-wideband array design is that the "phase bandwidth", defined as the frequency range over which the phase of the total radiated field of the array varies linearly with frequency, is taken into account as a design requirement in the synthesis process. Design examples of linear arrays with desired radiation patterns that are expected to remain unchanged over the bandwidth of interest are presented and simulated. Two example arrays, one with a wire dipole as its element and another using an elliptically-shaped disc dipole as the element are studied. Simulation results for far-field patterns, magnitude and phase characteristics, and other performance criteria such as side-lobe level and scanning range are presented.
Synthesis of two-dimensional planar arrays is carried out by employing the formulations developed for linear arrays but generalized to accommodate the geometry of planar rectangular arrays. As example designs, planar arrays with wire dipoles and elliptical-shaped disc dipoles are studied. The simulation results indicate that synthesis of ultra-wideband arrays can be accomplished successfully using the technique presented in this work. The proposed technique is robust and comprehensive, nonetheless it is understood that the achieved performance of a synthesized array and how closely the desired performance is met also depends on some of the choices the array designer makes and other constraints, such as number of elements, type of element, size, and ultimately cost.Ph. D.
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El-Makadema, Ahmed Talal. "Large scale broadband antenna array systems." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/large-scale-broadband-antenna-array-systems(d2586bcf-4d2f-4046-98bf-90860b52565b).html.
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Broadband antenna arrays have become increasingly popular for various imaging applications, such as radio telescopes and radar, where high sensitivity and resolution are required. High sensitivity requires the development of large scale broadband arrays capable of imaging distant sources at many different wavelengths, in addition to overcoming noise and jamming signals. The design of large scale broadband antenna arrays requires large number antennas, increasing the cost and complexity of the overall system. Moreover, noise sources often vary, depending on their wavelengths and angular locations. This increases the overall design complexity particularly for broadband applications where the performance depends not only on the required bandwidth, but also on the frequency band.This thesis provides a study of broadband antenna array systems for large scale applications. The study investigates different tradeoffs associated with designing such systems and drives a novel design approach to optimize both their cost and performance for a wide range of applications. In addition, the thesis includes measurements of a suitable array to validate the computational predictions. Moreover, the thesis also demonstrates how this study can be utilized to optimize a broadband antenna array system suitable for a low frequency radio telescope.
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Jafri, Ahsan. "Array signal processing based on traditional and sparse arrays." Thesis, University of Sheffield, 2019. http://etheses.whiterose.ac.uk/23072/.
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Array signal processing is based on using an array of sensors to receive the impinging signals. The received data is either spatially filtered to focus the signals from a desired direction or it may be used for estimating a parameter of source signal like direction of arrival (DOA), polarization and source power. Spatial filtering also known as beamforming and DOA estimation are integral parts of array signal processing and this thesis is aimed at solving some key probems related to these two areas. Wideband beamforming holds numerous applications in the bandwidth hungry data traffic of present day world. Several techniques exist to design fixed wideband beamformers based on traditional arrays like uniform linear array (ULA). Among these techniques, least squares based eigenfilter method is a key technique which has been used extensively in filter and wideband beamformer design. The first contribution of this thesis comes in the form of critically analyzing the standard eigenfilter method where a serious flaw in the design formulation is highlighted which generates inconsistent design performance, and an additional constraint is added to stabilize the achieved design. Simulation results show the validity and significance of the proposed method. Traditional arrays based on ULAs have limited applications in array signal processing due to the large number of sensors required and this problem has been addressed by the application of sparse arrays. Sparse arrays have been exploited from the perspective of their difference co-array structures which provide significantly higher number of degrees of freedoms (DOFs) compared to ULAs for the same number of sensors. These DOFs (consecutive and unique lags) are utilized in the application of DOA estimation with the help of difference co-array based DOA estimators. Several types of sparse arrays include minimum redundancy array (MRA), minimum hole array (MHA), nested array, prototype coprime array, conventional coprime array, coprime array with compressed interelement spacing (CACIS), coprime array with displaced subarrays (CADiS) and super nested array. As a second contribution of this thesis, a new sparse array termed thinned coprime array (TCA) is proposed which holds all the properties of a conventional coprime array but with $\ceil*{\frac{M}{2}}$ fewer sensors where $M$ is the number of sensors of a subarray in the conventional structure. TCA possesses improved level of sparsity and is robust against mutual coupling compared to other sparse arrays. In addition, TCA holds higher number of DOFs utilizable for DOA estimation using variety of methods. TCA also shows lower estimation error compared to super nested arrays and MRA with increasing array size. Although TCA holds numerous desirable features, the number of unique lags offered by TCA are close to the sparsest CADiS and nested array and significantly lower than MRA which limits the estimation error performance offered by TCA through (compressive sensing) CS-based methods. In this direction, the structure of TCA is studied to explore the possibility of an array which can provide significantly higher number of unique lags with improved sparsity for a given number of sensors. The result of this investigation is the third contribution of this thesis in the form of a new sparse array, displaced thinned coprime array with additional sensor (DiTCAAS), which is based on a displaced version of TCA. The displacement of the subarrays generates an increase in the unique lags but the minimum spacing between the sensors becomes an integer multiple of half wavelength. To avoid spatial aliasing, an additional sensor is added at half wavelength from one of the sensors of the displaced subarray. The proposed placement of the additional sensor generates significantly higher number of unique lags for DiTCAAS, even more than the DOFs provided by MRA. Due to its improved sparsity and higher number of unique lags, DiTCAAS generates the lowest estimation error and robustness against heavy mutual coupling compared to super nested arrays, MRA, TCA and sparse CADiS with CS-based DOA estimation.
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Han, Yi. "Development of nonlinear reconfigurable control of reconfigurable plants using the FPGA technology." Thesis, [S.l. : s.n.], 2008. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1011&context=td_cput.
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Manninen, O. (Olli). "Modelling the antenna arrays using MATLAB-application Sensor Array Analyzer." Bachelor's thesis, University of Oulu, 2017. http://urn.fi/URN:NBN:fi:oulu-201705302196.
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In this thesis, the antenna arrays researched and modelled using Sensor Array Analyzer- application (SAA) from MATLAB. The objective is to explore the array modelling capabilities of the SAA application. This thesis shows that SAA is versatile software for modelling the radiation patterns using 2D or 3D plots, but there are couple of missing features. SAA allows user to import the used code to MATLAB for code modification. Data imported from MATLAB to SAA using variables, for example importing dipole, antenna locations for conformal array and complex coefficients for beamforming. Antenna array wideband usage at SAA discussed and example shown. At SAA, grating lobes seen at 2D and 3D plots and grating lobe- diagram is also used and explained. SAA has no built-in option for mutual coupling compensation. Other practical method for modelling and compensation of mutual coupling are discussedTässä kandidaatintyössä tutkittiin eri geometrian omaavia antenniryhmiä ja niiden mallinnusta MATLAB-ohjelmiston lisäosan SAA:n (Sensor Array Analyzer) avulla. Tehtävänä oli tutkia antenniryhmän eri osa-alueiden mallinnuksen mahdollisuuksia ja rajoituksia kyseisellä ohjelmistolla. Tutkimuksen tuloksena todetaan, että SAA on monipuolinen ohjelmisto antenniryhmien säteilykuvioiden graafiseen havainnollistamiseen 2D- tai 3D-muodossa, vaikkakin muutama perusominaisuus puuttui. Työssä tutkittiin, miten SAA-ohjelmistosta voidaan siirtää käytetty koodi MATLAB-ohjelmistoon sen mahdollista lisämuokkausta varten ja kuinka MATLAB-ohjelmistosta tuodaan tietoa SAA-ohjelmistoon erilaisina muuttujina. Muuttujia tarvitaan esimerkiksi, kun ohjelmistoon tuodaan antennin säteilykuvio, tai sovellettu antenniryhmä sekä niiden kompleksiset kertoimet keilanmuodostusta varten. Laajakaistaisten antenniryhmien säteilykuvion mallinnusta testattiin ja havainnollistettiin. Sivukeiloja, joilla on sama teho pääkeilan kanssa, tarkasteltiin ja niiden havainnollistamiseen luotua diagrammia testattiin. Antennien välisen keskinäiskytkennän mallintamisen mahdollisuuksia tarkasteltiin ja sen vaikutusta säteilykuvioon pohdittiin. Tämän työn tarkoituksena oli selvittää SAA-ohjelmiston pääpiirteiset ominaisuudet ja heikkoudet. Kyseistä tietoa käytetään antenniryhmien keilasynteesiä tutkiessa. Antenniryhmiä voi mallintaa huomattavasti nopeammin ja helpommin käyttämällä SAA-ohjelmistoa, kuin kirjoittamalla itse MATLAB-koodi tai simuloimalla antenniryhmän sähkömagneettinen 3D-malli. Ohjelmiston heikkoudetkin voidaan välttää muokkaamalla koodia haluamalla tavalla. Antenniryhmiä tullaan tulevaisuudessa hyödyntämään IoT-laitteissa ja langattomassa 5G teknologiassa
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Sharma, Akshay. "Place and route techniques for FPGA architecture advancement /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6108.
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Leonard, Cathy Wood. "Optical feeds for phased array antennas." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80079.
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This thesis investigates optical feed methods for phased array antennas. The technical and practical limitations are analyzed and an optimum design is determined. This optimum optical feed is a two-beam interferometric approach which uses acoustooptic phase control. The theory is derived; a computer model is developed; and the limitations are determined. Design modifications are suggested which reduce limitations and greatly extend the range of applications.Master of Science
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Takamizawa, Koichiro. "Array antenna synthesis including element and feed coupling." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/76146.
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Precise radiation pattern control for an array antenna requires precise control of array element excitations. One application is that of low side lobe patterns. Classical synthesis methods for the desired pattern may not be realized in practice due to coupling effects. Coupling occurs in two forms: the mutual coupling between array elements and the coupling introduced by the feed networks. Ideally one could account for such coupling within the array architecture during the design process and alter the feed network parameters to adjust for such coupling. Unfortunately, this is a nonlinear problem requiring special solution techniques.
This report presents the solution techniques for determining feed network parameter values that compensate for antenna-feed network coupling. Scattering parameter representations of the antenna array and the feed networks are used. Examples of various array configurations for microstrip antenna arrays and for dipole arrays are included.Master of Science
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Schodorf, Jeffrey Brian. "Array processing techniques for interference suppression in mobile communications systems." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12971.
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Walter, Thomas. "Dental reference array." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-139683.
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Liu, Guang. "Photovoltaic array simulators." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25103.
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Two basic types of photovoltaic (PV) array simulator have been designed and tested. The first involves the use of a pilot panel and variable light source. It is implemented with analogue circuits. A stability analysis based on Popov's method is presented for this simulator with resistance-inductance (R-L) loads. In the second, characteristic array curves are stored in the memory of a microprocessor-based simulator. The design of both simulators is based on the transfer function method. By using the computing facility available, a stability study for the Type I simulator and some dynamic simulations are carried out. Both simulators are capable of driving a special load, namely, an experimental solar pumping system. The experimental results for both types of' simulator are satisfactory in terms of steady state precision and dynamic behaviour when used with this load.
Compared with previously-reported PV array simulator designs [6,7,8,9,18], the two simulators described here have the following distinctive features:
1. A new method of sample curve generation for the Type II simulator results in relatively short sampling period and small memory size.
2. The sample curves of the type II simulator are based directly on the real PV array to be simulated. They are more accurate than the sample curves in references [6,7,9]. 3. Different loads (R, R-L and an experimental solar pumping system) have been considered in the design and have been tested in laboratory.
4. A stability analysis and some dynamic simulations are presented for the type I simulator. An analysis of this type has not been reported in previous studies [6,7,8,9,18].Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Manra, Vikas. "Efficient array-multipliers /." Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1240704201&sid=4&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Dowlut, Naushad Hussein. "Superresolution array design." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266213.
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Wan, Shuang. "Parametric array calibration." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/4902.
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The subject of this thesis is the development of parametric methods for the calibration of array shape errors. Two physical scenarios are considered, the online calibration (self-calibration) using far-field sources and the offline calibration using near-field sources. The maximum likelihood (ML) estimators are employed to estimate the errors. However, the well-known computational complexity in objective function optimization for the ML estimators demands effective and efficient optimization algorithms. A novel space-alternating generalized expectation-maximization (SAGE)-based algorithm is developed to optimize the objective function of the conditional maximum likelihood (CML) estimator for the far-field online calibration. Through data augmentation, joint direction of arrival (DOA) estimation and array calibration can be carried out by a computationally simple search procedure. Numerical experiments show that the proposed method outperforms the existing method for closely located signal sources and is robust to large shape errors. In addition, the accuracy of the proposed procedure attains the Cram´er-Rao bound (CRB). A global optimization algorithm, particle swarm optimization (PSO) is employed to optimize the objective function of the unconditional maximum likelihood (UML) estimator for the farfield online calibration and the near-field offline calibration. A new technique, decaying diagonal loading (DDL) is proposed to enhance the performance of PSO at high signal-to-noise ratio (SNR) by dynamically lowering it, based on the counter-intuitive observation that the global optimum of the UML objective function is more prominent at lower SNR. Numerical simulations demonstrate that the UML estimator optimized by PSO with DDL is optimally accurate, robust to large shape errors, and free of the initialization problem. In addition, the DDL technique is applicable to a wide range of array processing problems where the UML estimator is employed and can be coupled with different global optimization algorithms.
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Southwell, David Thomas. "Columnar array networks." Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297157.
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Wang, Ji-yong 1967. "Hybrid ultrasonic array." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84216.
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Pacheco, Shaun, and Shaun Pacheco. "Array Confocal Microscopy." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/623252.
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Confocal microscopes utilize point illumination and pinhole detection to reject out-of-focus light. Because of the point illumination and detection pinhole, confocal microscopes typically utilize point scanning for imaging, which limits the overall acquisition speed. Due to the excellent optical sectioning capabilities of confocal microscopes, they are excellent tools for the study of three-dimensional objects at the microscopic scale. Fluorescence confocal microscopy is especially useful in biomedical imaging due to its high sensitivity and specificity. However, all designs for confocal microscopes must balance tradeoffs between the numerical aperture (NA), field of view (FOV), acquisition speed, and cost during the design process. In this dissertation, two different designs for an array confocal microscope are proposed to significantly increase the acquisition speed of confocal microscopes. An array confocal microscope scans an array of beams in the object plane to parallelize the confocal microscope to significantly reduce the acquisition time. If N beams are used in the array confocal microscope, the acquisition time is reduced by a factor of N. The first design scans an array of miniature objectives over the object plane to overcome the trade-off between FOV and NA. The array of objectives is laterally translated and each objective scans a small portion of the total FOV. Therefore, the number of objectives used in the array limits the FOV, and the FOV is increased without sacrificing NA. The second design utilizes a single objective with a high NA, large FOV, and large working distance designed specifically for whole brain imaging. This array confocal microscope is designed to speed up the acquisition time required for whole brain imaging. Utilizing an objective with a large FOV and scanning using multiple beams in the array significantly reduces the time required to image large three-dimensional volumes. Both array confocal microscope designs use beam-splitting gratings to efficiently split one laser beam into a number of equal energy outgoing beams, so this dissertation explores design methods and analyses of beam-splitting gratings to fabrication errors. In this dissertation, an optimization method to design single layer beam-splitting gratings with reduced sensitivity to fabrication errors is proposed. Beam-spitting gratings are typically only designed for a single wavelength, so achromatic beam-splitting grating doublets are also analyzed for possible use in array confocal microscopes with multiple excitation wavelengths. An analysis of the lateral shift between grating layers in the achromatic grating doublet proves grating profiles with constant first spatial derivatives are significantly less sensitive than continuous phase profiles. These achromatic grating doublets have designed performance at two wavelengths, but the diffraction angles at the two wavelengths differ. To overcome that limitation, scale-invariant achromatic gratings are designed, which not only provide designed performance at two wavelengths, but also equal diffraction angles at two wavelengths.
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Willerton, Marc. "Array auto-calibration." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11684.
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In this thesis, efficient methods are presented to calibrate large or small aperture array systems containing different types of uncertainties. specifically the challenge of reducing the number of external sources required to calibrate an array is addressed and array calibration methods suitable for use when sources may be operating in the "near-far" field of the array are developed. Together, this can ease the overheads involved in calibrating and recalibrating an array system. In addition to presenting novel array calibration algorithms, this thesis also presents a novel transformation allowing a planar array to be expressed as a virtual uniform linear array of a much larger number of elements. This allows the array manifold of a planar array, which in general consists of non-hyperhelical curves, to be expressed using a number of hyperhelices which each correspond to the array manifold of a linear array. This hyperhelical structure has the potential to ease calibration overheads as well as having many other potential applications in array processing. This thesis presents novel pilot and auto array calibration schemes for estimating different types of array uncertainties. A novel pilot calibration algorithm is proposed whereby a single source transmitting from a known location (i.e. a pilot) at two carrier frequencies is used to estimate geometrical uncertainties in a planar array. This is achieved by exploiting the frequency dependence on the boundary between the "near-far" and "far" field of the array. In addition, an auto-calibration method is presented which doesn't require any external sources to estimate array uncertainties. Here, geometrical, complex gain and local oscillator (i.e. frequency and phase) uncertainties associated with the array elements are considered. In this approach, array elements transmit in turn to the others which operate as an array receiver. Large and small array apertures are investigated. Throughout the thesis, extensive computer simulations are presented to analyse the performance of the algorithms developed.
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Efstathopoulos, Georgios. "Extended array manifolds." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11240.
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Amin, H. "Investigations into the hardware implementation of artificial neural networks." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263389.
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Eng, Cher Shin. "Digital antenna architectures using commercial off-the-shelf hardware." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FEng.pdf.
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Thesis (M.S. in Engineering Science (Electrical Engineering)--Naval Postgraduate School, December 2003.Thesis advisor(s): David C. Jenn, Roberto Cristi. Includes bibliographical references (p. 75-76). Also available online.
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Yasar, Temel Kaya. "Improvements In Doa Estimation By Array Interpolation In Non-uniform Linear Arrays." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607524/index.pdf.
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In this thesis a new approach is proposed for non-uniform linear arrays (NLA) which employs conventional subspace methods to improve the direction of arrival (DOA) estimation performance.
Uniform linear arrays (ULA) are composed of evenly spaced sensor elements located on a straight line. ULA's covariance matrix have a Vandermonde matrix structure, which is required by fast subspace DOA estimation algorithms. NLA differ from ULA only by some missing sensor elements. These missing elements cause some gaps in covariance matrix and Vandermonde structure is lost. Therefore fast subspace DOA algorithms can not be applied in this case. Linear programming methods and array interpolation methods can be used to solve this problem. However linear programming is computationally expensive and array interpolation is angular sector dependent and requires the same number of sensor in the virtual array. In this thesis, a covariance matrix augmentation method is developed by using the array interpolation technique and initial DOA estimates. An initial DOA estimate is obtained by Toeplitz completion of the covariance matrix. This initial DOA estimates eliminates the sector dependency and reduces the least square mapping error of array interpolation. A Wiener formulation is developed which allows more sensors in the virtual array than the real array. In addition, it leads to better estimates at low SNR. The new covariance matrix is used in the root-MUSIC algorithm to obtain a better DOA estimate. Several computer simulations are done and it is shown that the proposed approach improves the DOA estimation accuracy significantly compared to the same number of sensor ULA. This approach also increases the number of sources that can be identifed.
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Akyildiz, Isin. "Drection Of Arrival Estimation By Array Interpolation In Randomly Distributed Sensor Arrays." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607963/index.pdf.
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In this thesis, DOA estimation using array interpolation in randomly distributed sensor arrays is considered. Array interpolation is a technique in which a virtual array is obtained from the real array and the outputs of the virtual array, computed from the real array using a linear transformation, is used for direction of arrival estimation. The idea of array interpolation techniques is to make simplified and computationally less demanding high resolution
direction finding methods applicable to the general class of
non-structured arrays.In this study,we apply an interpolation
technique for arbitrary array geometries in an attempt to extend root-MUSIC algorithm to arbitrary array geometries.Another issue of array interpolation related to direction finding is spatial smoothing in the presence of multipath sources.It is shown that due to the Vandermonde structure of virtual array manifold vector obtained from the proposed interpolation method, it is possible to use spatial smoothing algorithms for the case of multipath sources.
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Sinclair, David Robert. "A study of the square kilometre array low-frequency aperture array." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:7b5047f4-5643-49be-aea8-e31512180267.
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This thesis primarily comprises simulations of SKA1-Low, the low-frequency aperture array of the Square Kilometre Array (SKA) radio telescope. Simulations assess how different design specifications would affect the telescope's performance and ability to undertake one of its key science projects: observing the Epoch of Reionisation (EoR). The simulations are based on the previous baseline design of ~ 260 000 dipole antennas in 1024 stations of 256 antennas each. It is found that errors in the gain and phase of signals at each antenna can significantly affect observations, with the greatest impact at the lowest frequencies. The EoR signal will be detectable at limited redshifts with gain errors of 10% and phase errors of 6 degrees, however to ensure the systematic noise contribution from these errors is always weaker than the EoR signal between z ~ 10 - 21 and spherical harmonic multipole coefficients l ~ 102 - 104 , the gain and phase errors may need to be less than or equal to approximately 5 x 10-6 and less than or equal to approximately 3 x 10-4 degrees, respectively. Alternative telescope layouts to the SKA1-Low baseline design of 1024 stations containing 256 antennas each are evaluated. Some telescope models which share antennas between stations, allowing stations to be formed in a flexible manner, are found to provide superior thermal noise sensitivity than the current design, but suffer greater detrimental effects from gain and phase errors when imaging. The implementation of the digital signal processing of a station beamformer is also discussed. Calculations show that five or nine Field Programmable Gate Arrays (FPGAs) with specifications comparable to the Virtex UltraScale+ XCVU13P could be used to beamform a single 256-antenna SKA1-Low station, depending on the utilisation rate of the FPGAs and the number of channels required.
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Goshi, Darren S. "Advanced retrodirective array and phased array architectures for wireless communication systems." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1414125501&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Terrell, Stephen John. "Design of a bistatic nearfield array for an expanded volume." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-03172005-140730/unrestricted/terrell%5Fstephen%5Fj%5F200505%5Fmast.PDF.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005.Rogers, Peter, Committee Chair ; Ginsberg, Jerry, Committee Member ; Trivett, David, Committee Member. Includes bibliographical references.
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Yang, Zhenchao. "High-Efficiency Passive and Active Phased Arrays and Array Feeds for Satellite Communications." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5741.
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Satellite communication (Satcom) services are used worldwide for voice, data, and video links due to various appealing features. Parabolic reflector antennas are typically used to serve a cost effective scheme for commercial applications. However, mount degradation, roof sag, and orbital decay motivate the need for beam steering. Limited scan range beam steering opens a third option for electronic beam steering with lower cost than full aperture phased arrays and higher tracking speed and accuracy than mechanical-only steering.Multiple high efficiency passive patch array feeds were designed, fabricated, and measured, including a 2x2 MSA array, a stacked shorted annular patch antenna, and an SIW-fed hexagonal array feed based on PTFE material, achieving performance comparable to a horn feed. For multiband dual polarization applications, passive MSA feed solutions are also provided. Multiple MSA array feeds with high isolation were designed for dual band dual polarization applications. More functionality can be realized with multi-layer PCB techniques for complex communication scenarios.Limited scan range electronic beam-steering with a parabolic reflector fed by an active array feed which only needs gain control was demonstrated experimentally, leading to a low cost and effective solution for active beam scanning. A cost-effective flat-panel phased array with limited scan range electronic beam-steering was proposed by tiling high efficiency 4x4 passive subarrays and performing beam scanning at the tile level. The sidelobe issue was also investigated to comply with the pattern mask requirement set by FCC.To enable better use of circularly polarized (CP) MSAs for electronically beam-formed antenna systems, the impact of mutual coupling on the performance of high-sensitivity dual-polarized receivers for satellite communications applications was analyzed. A new analysis method for intrinsically dual-CP MSAs based on an equivalent circuit model and Jones matrices was proposed and validated to overcome the port isolation challenge. The model provides accurate estimates of impedances and S-parameters, as well as field parameters such as axial ratio. The feasible region for XPI and impedance mismatch factor is found for dual CP antennas. The circuit model enables multiple useful applications. Effective decoupling and matching schemes was proposed and demonstrated, leading to a high isolation, good match, and wide AR bandwidth dual CP MSA for satellite communications.
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Ng, Kwong-Tai. "Admittance properties of a slot array with parasitic wire arrays in a stratified medium /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487259580262744.
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Hanson, Timothy B. "Cascade adaptive array structures." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1173207031.
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Malik, Usama Computer Science & Engineering Faculty of Engineering UNSW. "Configuration encoding techniques for fast FPGA reconfiguration." Awarded by:University of New South Wales. School of Computer Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/26212.
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This thesis examines the problem of reducing reconfiguration time of an island-style FPGA at its configuration memory level. The approach followed is to examine configuration encoding techniques in order to reduce the size of the bitstream that must be loaded onto the device to perform a reconfiguration. A detailed analysis of a set of benchmark circuits on various island-style FPGAs shows that a typical circuit randomly changes a small number of bits in the {\it null} or default configuration state of the device. This feature is exploited by developing efficient encoding schemes for configuration data. For a wide set of benchmark circuits on various FPGAs, it is shown that the proposed methods outperform all previous configuration compression methods and, depending upon the relative size of the circuit to the device, compress within 5\% of the fundamental information theoretic limit. Moreover, it is shown that the corresponding decoders are simple to implement in hardware and scale well with device size and available configuration bandwidth. It is not unreasonable to expect that with little modification to existing FPGA configuration memory systems and acceptable increase in configuration power a 10-fold improvement in configuration delay could be achieved. The main contribution of this thesis is that it defines the limit of configuration compression for the FPGAs under consideration and develops practical methods of overcoming this reconfiguration bottleneck. The functional density of reconfigurable devices could thereby be enhanced and the range of potential applications reasonably expanded.
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Koh, Shannon Computer Science & Engineering Faculty of Engineering UNSW. "Generating the communication infrastracture for module-based dynamic reconfiguration of FPGas." Publisher:University of New South Wales. Computer Science & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41418.
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Current approaches to supporting module-based FPGA reconfiguration focus on various aspects and sub-problems in the area but do not combine to form a coherent, top-down methodology that factors low-level device parameters into every step of the design flow. This thesis proposes such a top-down methodology from application specification to low-level implementation, centered around examining the problem of generating a point-to-point communications infrastructure to support the changing interfaces of dynamically placed modules. Low-level implementation parameters are considered at every stage to ensure that area, timing and budget constraints of the application are met. The approach advocates the regular layout of modules surrounded by a wiring harness supporting the communications for those modules, and thus provides an advanced understanding of how to implement the "fixed wiring harness" model of reconfigurable computing proposed by Brebner. Results have shown that compared to flattened net lists the regularity of the layout does not impose significant overheads on critical path delays. At high communication densities it can even result in lower delays. The core of the methodology is an infrastructure generation process that allocates modules to slots and merges configuration graphs to form wiring harnesses that support the communications for these merged configurations. This thesis suggests methods and evaluates algorithms for configuration graph merging so as to reduce run-time reconfiguration overheads. Initial experiments with a greedy merging algorithm performed on an optical flow application resulted in a substantial reduction of 64% in reconfiguration time. The effects of graph merging with the initial greedy algorithm and an improved dynamic programming algorithm were explored for a range of device sizes and architectural parameters. Results show that configuration merging using the greedy method results in significant reductions to the reconfiguration delay. The dynamic programming algorithm provides consistent improvements above and beyond the savings provided by the greedy method. In addition, a strong correlation was identified between the quality of front-end design activities such as partitioning and the effectiveness of back-end implementations. The methodology is integrated into the Xilinx commercial tool flow for partial reconfiguration, and is effective for implementing applications for module-based FPGA reconfiguration where the modules and their communications requirements are known at design time. It also allows a system designer to consider alternate device sizes and parameters until a set is found that satisfies the application constraints.
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Wood, Christopher Landon. "Runtime partial FPGA reconfiguration." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15051.
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Galindo, Juan Manuel. "A novel partial reconfiguration methodology for FPGAs of multichip systems /." Online version of thesis, 2008. http://hdl.handle.net/1850/7784.
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Rajagopalan, Kamal. "An FPGA architecture for improved arithmetic performance /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16460.pdf.
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Khan, Iqtidar Ahmad. "Analysis and Synthesis of a New Class of Low Side Lobe Planar Arrays." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/93222.
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Numerical techniques for designing planar arrays with low side lobe level often require memory intensive optimization algorithms and also initialization in the form of some known values of radiation pattern parameters beforehand - information that may not be available when designing arrays. A few analytical methods exist in the literature that can be used to design rectangular lattices of isotropic elements for desired half-power beamwidth and side lobe level, but the number of elements of the array often should be known before the design process. Some array designs based on analytical techniques may suffer from severe performance limitations, an example is the uniformly excited array which cannot produce side lobe levels below ̶13.3 dB.
The goal of this study is to present an analytical technique for synthesis of planar arrays that, for specified radiation pattern requirements, not only provides quick solutions for the required number of elements and its distribution along the length and width of the array rectangular lattice, but also produces low side lobes without any limitation. A new class of non-uniformly excited equally spaced planar arrays is introduced and investigated in this study. The new array uses the patterns of uniformly excited linear arrays as its building blocks and has a separable element current distribution, hence making it mathematically convenient to analyze its radiation properties in terms of those of its constituent linear arrays. The proposed planar array does not suffer from the side lobe level limitation of uniformly excited planar arrays, and its synthesis, due to the analytical nature of description of its radiation properties, does not require iterative procedures that are inherent to numerical techniques.
Radiation characteristics of the proposed planar array, including directivity, side lobe level, half-power beamwidths, far-field three dimensional radiation patterns, and element excitation currents, are examined and simulation results for several example cases are presented. The analysis culminates with successfully mapping a continuous radiation pattern to discrete element currents in a rectangular lattice geometry.
The synthesis procedure is validated by successfully designing various planar arrays with desired requirements in terms of side lobe level and half-power beamwidths in the principal planes. Several design examples are presented. Radiation characteristics of the synthesized arrays are compared with the desired design requirements which were used as input information in the synthesis process. For the cases studied, the achieved performance characteristics are close to the desired ones.MS
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Khan, Asim Ali. "Performance optimisation of small antenna arrays." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/performance-optimisation-of-small-antenna-arrays(759e6929-04ab-408c-aee3-404c72711cdb).html.
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This thesis addresses radiation pattern synthesis problems for small linear periodic phased arrays (with array elements less then 10). Due to the small array size conventional pattern synthesis techniques fail to produce the required results. In the case of practical small arrays, mutual coupling and element pattern asymmetric effect degrade the array radiation performance. The main performance metrics considered in this thesis include side lobe level (SLL), gain, halfpower beamwidth (HPBW) and mainbeam scan direction. The conventional pattern synthesis approaches result in sub optimal gain, SLL and HPBW due to the limited number of elements and the mutual coupling involved. In case of difference pattern synthesis these factors resulted in lower difference pattern slope, degraded SLL and difference peak asymmetry. The sum and difference patterns are used in monopulse arrays and a simplified feed that could produce both patterns with acceptable radiation properties is of interest and has been examined (chapter 5). A conventional technique is applied to small arrays to synthesise a sector beam and there is limited control over the radiation pattern. It is shown that the mutual coupling has significant effect on the array radiation pattern and mitigation is necessary for optimum performance (chapter 6). Furthermore, wideband phased arrays may have a natural limitation of the HPBW in low gain applications and minimisation of the variation becomes important. Also the SLL variations for wideband antenna arrays in the presence of mutual coupling considerably degrade the radiation pattern. The mutual coupling degrades significantly the radiation pattern performance in case of small scanning wideband arrays (chapter 7). It is the primary goal of this thesis to develop an optimisation scheme thatis applied in the above scenarios (chapters 3 & 4). The only degree of freedom assumed is the array excitation. Optimised amplitude and phase for each element in the array are determined by the proposed scheme, concurrently. The deterministic optimisation techniques reported in the literature for the pattern synthesis may involve complicated problem modelling. The heuristic opti-misation techniques generally are computationally expensive. The proposedIntelligent z-space Boundary Condition-Particle Swarm Optimiser (IzBC-PSO)is based on a heuristic algorithm. This scheme can be applied to a wider rangeof problems without significant modifications and requires fewer computationscompared to the competing techniques.In order to verify the performance of IzBC-PSO antenna array measure-ments were performed in the receiving mode only using the online and offlinedigital beamforming setups described in chapter 8. The measurement resultsshow that the proposed scheme may be successfully applied with both onlineand offline digital beamformers for a practical small array (chapter 8).
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Dalevi, Mathias. "S-Band Antenna Array." Thesis, Uppsala University, Astronomy and Space Physics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126302.
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This report presents concepts for a planar active electronically scanned antenna(AESA). The goal of the project was to devlop a low-weight, low profile, thin, S-band antenna with wide-scan angle capabilities. In the final concept the service aspects of the T/R-modules was also taken into acount in order to allow easy and fast replacements of these components. The antenna was designed and optimised using the commercial software Ansoft HFSS. A prototype of the antenna was constructed and later measured and verified. The final concept is a 2m×2m antenna with an estimated weight of around 320 kg, around 11 cm thick (where the thickness of the antenna element is 1.76 cm) and has a maximum scan angle range of more than 45 degrees (with <–10dB active reflection) in the frequency band 3–3.5 GHz.
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Otsuka, Takuma. "Bayesian Microphone Array Processing." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188871.
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Kyoto University (京都大学)0048
新制・課程博士
博士(情報学)
甲第18412号
情博第527号
新制||情||93(附属図書館)
31270
京都大学大学院情報学研究科知能情報学専攻
(主査)教授 奥乃 博, 教授 河原 達也, 准教授 CUTURI CAMETO Marco, 講師 吉井 和佳
学位規則第4条第1項該当
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More, Daesha. "Microhotplate Sensor Array Fabrication." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/MoreD2007.pdf.
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Mony, Madeleine. "Reprogrammable optical phase array." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103276.
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The evolving needs of network carriers are changing the design of optical networks. In order to reduce cost, latency, and power consumption, electrical switches are being replaced with optical switching fabrics at the core of the networks. An example of such a network is an Agile All-Photonic Network (AAPN).This thesis presents a novel device that was designed to operate as an optical switch within the context of an AAPN network. The device is a Reprogrammable Optical Phase Array (ROPA), and the design consists of applying multiple electric fields of different magnitudes across an electro-optic material in order to create a diffractive optical element. The configuration of the electric fields can change to modify the properties of the diffractive device.
Such a device has a wide range of potential applications, and two different ROPA designs are presented. Both designs are optimized to function as 1xN optical switches. The switches are wavelength tunable and have switching times on the order of microseconds. The ROPA devices consist of two parts: a bulk electro-optic crystal, and a high-voltage CMOS chip for the electrical control of the device. The design, simulation, fabrication and testing of both the electrical and optical components of the devices are presented.
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Alexiou, Angeliki. "Bounds in array processing." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249378.
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Aytun, Alper. "Frequency diverse array radar." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/5113.
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Approved for public release; distribution is unlimitedElectronic scanning is the most desirable feature of state-of-the-art radar systems. With electronic scanning, it is possible to steer the main beam of an array antenna instantaneously into a desired direction where no mechanical mechanism is involved in the scanning process. Electronic scanning methods including phase scanning, time delay scanning, and frequency scanning have been used in various radar applications; however new and cheaper scanning methods are still being investigated. It is the purpose of this thesis to investigate an array configuration called frequency diverse array (FDA), which gives rise to range-, time-, and angle-dependent scanning without using phase shifters. In this thesis, first, frequency diverse array as a time-modulated array is presented. A general analysis and the theory of time domain scanning is given. Equations derived for a time-modulated frequency diverse array are simulated using MATLAB. Amplitude tapering and Fourier series expansion is implemented in MATLAB and the results are provided for comparison. Secondly, analysis of a frequency diverse array is presented. Time-, range-, and angle-dependent electronic scanning is achieved by applying a small amount of frequency shift among the antenna elements. The simulation results for radiation patterns with various excitation types are given. Lastly, the radar applications of FDA are considered. The received power from a target at a fixed range is simulated in MATLAB and the results are presented.
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Li, Yan 1978 July 15. "Gene expression array simulator." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87263.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2002."May 10, 2002.
Includes bibliographical references (leaf 141).
by Yan Li.
M.Eng.
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Fofonoff, Timothy Andrew 1977. "Brain microelectrode array systems." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/41031.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (leaves 110-114).
New methods for manufacturing microelectrode array assemblies, passive devices designed for intracortically recording brain activity in nonhuman primates, were developed and explored. Wire electrical discharge machining (EDM), chemical etching, micromilling, parylene deposition, and laser ablation were some of the processes employed to create distinctive microstructures with fine features and high aspect ratios. These microstructures, constructed from a variety of metals and polymers, were assembled to form the mechanical front end of a brain-machine interface (BMI). The developed techniques were used to produce microelectrode array assemblies for the Telemetric Electrode Array System (TEAS), a surgically implantable wireless device to be used for motor cortex studies in nonhuman primates. Two prototypes of the TEAS microelectrode array assemblies were implanted in animals in order to validate the design and the manufacturing processes. Neural activity was successfully recorded. Future work is required in order to refine and further automate the processes. Similar devices could one day develop into neural prostheses for clinical use by outputting motor intent captured from brain activity in paralyzed patients.
by Timothy Andrew Fofonoff.
S.M.
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Rusholme, Benjamin Alan. "The very small array." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621310.
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Schluntz, Justine Oakley. "Tidal turbine array modelling." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:b342fda1-a311-4783-8249-9b1515e0ad62.
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Computational fluid dynamics (CFD) is used in this thesis to model wind and tidal stream turbines and to investigate tidal turbine fence performance. There are two primary objectives of this work. The first is to develop and validate an actuator line method for the simulation of wind and tidal turbines which applies the blade forces to the flow field without the need for a regularisation kernel. The second is to examine tidal fences using, in part, the newly developed actuator line method. A potential flow equivalence method for determining the relative velocity to the blade chord and flow angle at the rotor blades in the actuator line method is proposed and validated. Results for simulations using this method compare favourably with those from both experiments and alternative computational methods, although the present model’s results deviate from experimental results in the vicinity of the blade tips. A CFD-embedded blade element-momentum tool is used to design rotors for operation in infinitely wide tidal fences spanning a tidal channel. Rotors are designed for fences with several different blockage ratios, with those designed for high blockage flows having greater solidity than those designed for operation in fences with lower blockage. It is found that designing rotors for operational blockage conditions can significantly improve the power output achieved by a tidal fence. Improved power output for higher blockage conditions is achieved by the application of greater thrust to the flow. Actuator line simulations of short (up to 8 turbines) fences with varying intra-rotor spacing and number of rotors confirm that hydrodynamic performance of the rotors improves as the spacing is reduced and as rotors are added to a fence. The position of a rotor within the fence impacts its performance; rotors at the ends of a fence extract reduced power compared to those at the centre of the fence, particularly for tip speed ratios greater than the design tip speed ratio.
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Lin, Yuanzhi. "Active Antenna Oscillator Array." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1231873914.
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Smith, Edward J. "The diode array velocimeter." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040337/.
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