Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 78 for “"phased arrays"”.
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Nanophotonic visible light phased arrays
Previously demonstrated integrated optical phased arrays have primarily been implemented in silicon-based platforms and have therefore been limited to operation at infrared wavelengths, where silicon provides low-loss transmission. Developing integrated optical phased arrays for visible wavelengths …
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Integrated optical phased arrays for lidar applications
… receiving increasing interest are Nanophotonic Phased Arrays (NPAs), which offer free space emission of a manipulated beam that can be steered, focused, have controlled angular momentum and even create holograms. Still, some substantial challenges remain in applying these NPAs to real systems. …
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Intracavitary ultrasound phased arrays for thermal therapies
Thesis (Ph. D.)--Massachusetts Institute of Technology, Whitaker College of Health Sciences and Technology, 1997.
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Modeling of acoustic waves for linear phased arrays
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.
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Modeling and Optimization of Electromagnetic Phased Arrays for Hyperthermia
Progress in the modeling and optimization of phased arrays for electromagnetic hyperthermia is reported. The electromagnetic phased array has the potential to overcome many of the difficulties associated with noninvasive hyperthermia, but is only effective if the driving amplitudes and phases of …
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Integrated optical phased arrays for three-dimensional display applications
… development of silicon-based integrated optical phased arrays (OPAs) for light detection and ranging (LiDAR) and free-space communications. However, silicon is limited to operating at infrared wavelengths since its bandgap prevents visible light transmission. The development of integrated OPAs …
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Integrated optical phased arrays : augmented reality, LiDAR, and beyond
Integrated optical phased arrays, fabricated in advanced silicon-photonics platforms, enable manipulation and dynamic control of free-space light in a compact form factor, at low costs, and in a non-mechanical way. As such, integrated optical phased arrays have emerged as a promising technology for …
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Integrated LIDAR with optical phased arrays in silicon photonics
… is then extended by utilizing optical phased arrays as a transmitter and receiver for solid-state beam steering. The phased array utilized has a grouped cascaded phase shifter architecture and is shown to have a steering range of 46°x36°. This is the first integrated coherent LIDAR …
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Ultrasonic phased arrays of the condition assessment of concrete structures
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.
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Reduction of Near-Field Grating Lobes in Sparse Acoustic Phased Arrays
<p>Acoustic phased arrays with inter-element spacings of greater than one half-wavelength will produce grating lobes that decrease the usefulness of the array. With many array configurations, the near-field and far-field character of these lobes is significantly different -- an optimization of the …
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Analysis and Design of Ultrasound Phased Arrays for Hyperthermia Cancer Therapy
Acoustic phased arrays, which can be focused and steered electronically, offer an attractive alternative to the mechanically scanned focused ultrasound systems currently in use in hyperthermia cancer therapy. This thesis introduces a new method which will allow the direct synthesis, without …
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Spatially-Adaptive LiDAR and Underwater Communications Using Integrated Optical Phased Arrays
… systems. In particular, integrated optical-phased-array-based (OPA-based) technologies, such as solid-state LiDAR and free-space optical communications (FSOC) systems, show promise to revolutionize the way we sense and communicate. This thesis enables new integrated-OPA-based solid-state …
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Development and experimental characterizaton of ultrasonic phased arrays for nondestructive testing
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.
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Analysis of Power Deposition Patterns and Ultrasonic Phased Arrays for Localized Hyperthermia
… precision local hyperthermia by using ultrasonic phased arrays. A method for calculating ultrasonic fields and examples of field patterns produced by square ultrasonic sources are presented. Temperature distributions are calculated from power deposition patterns by using a finite difference …
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Silicon-Based PALNA Transmit/Receive Circuits for Integrated Millimeter Wave Phased Arrays
Phased array element RF front ends typically use single pole double throw (SPDT) switches or circulators with high isolation to prevent leakage of transmit energy into the receiver circuits. However, as phased-array designs scale to the millimeter-wave range, with high degrees of integration, the …
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Deep localized hyperthermia with ultrasound-phased arrays using the pseudoinverse pattern synthesis method
… points in the treatment volume using ultrasound phased arrays. This method, called the pseudoinverse pattern synthesis method, reduces the pattern synthesis problem to one of estimating the minimum-norm least-square solution to a matrix equation of the form, Hu = p, where u is the array …
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Fresnel-focusing and bessel-beam integrated optical phased arrays for optical trapping applications
… microns of the chip surface. Integrated optical phased arrays, which manipulate and dynamically steer light, provide one possible approach to scaling and arbitrary tweezing of optical traps. However, current on-chip optical phased array demonstrations have focused on systems which form and steer …
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Power efficient Transmit/Receive (T/R) Elements for Integrated mm-Wave Phased Arrays
… and high-resolution imaging systems. Large-scale phased arrays have been exploited in such application for their beam forming and null steering capabilities, resulting in high directivity and improved SNR. But growing DC power consumption (Pdiss) in such large scale arrays has become an on-going …
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A Novel Unit Cell Antenna for Highly Integrated Phased Arrays in the SHF Band
<p>Phased arrays are electromagnetic antenna systems comprised of many radiating elements and processing electronics. Radiating elements are typically positioned in an orderly grid within the antenna aperture. In the receive mode of operation, radiating elements capture some of the signal energy …
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Design and simulation of three-dimensional hologram emitting phased arrays in the near field
… technologies to generate a method to design a phased array that will emit three-dimensional holograms and investigate the scalability of the phased arrays. This thesis will cover the design and functionality of optical phased arrays and how they have been previously used to emit patterns in the …
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