Jingru Zhou PhD final defense

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

Jingru Zhou

Advisor: V. John Mathews

 

 

 

Impact location estimation and damage classification for composite structures

 

 

Impacts that occur during service or maintenance are major causes of in-service damage of aerospace structures. Therefore, impact location estimation techniques and damage assessment are key components for structural health monitoring (SHM), especially for large and expensive structures such as aircraft and space vehicles. This dissertation focuses on composite structures, which typically are anisotropic and consequently have more complex wave propagation properties than isotropic structures. The SHM system employs a sensor array that acquires acoustic emission (AE) signals emitted from impact locations. In this dissertation, two impact location estimation algorithms that employ AE signals are proposed for anisotropic composite structures. The first one requires minimum velocity information, while the second one does not require any prior knowledge of the direction and location-dependent wave propagation properties within the structures and it is able to perform fast and accurate impact location estimation. The performance of the algorithms is first assessed by numerical simulations to understand the capabilities of the algorithms and to design the experimental setup. Experimental validation was also performed using different types of composite structures. The results demonstrated the ability of the methods to accurately estimate the impact location in composite structures without prior knowledge of the wave propagation properties of the structures.

 

The second goal of this dissertation is damage assessment from AE signals and focuses on damage classification. Specifically, the goal is to identify the most important features of the AE signals that identify impacts resulting in structural damage and also classify the damage as either delamination only or delamination plus fiber breakage. An efficient machine learning approach based on logistic regression is developed for this purpose. The experimental preparations which included composite structure selection, sensor selection, type of impacting experiments and inspection for damage were carefully and systematically set up for training and testing the method. The most useful features of the AE signals were obtained from the training data. Cross-validation experiments indicated that the methods identified impacts resulting in damage with 100% accuracy. Classification of damage type showed a 74% accuracy.

 

 

 

Wednesday January 4, 2017

1:30 PM, ECE conference room

Merrill Engineering Building (MEB) room 2109

The public is invited

 

Xiaojun Sun PhD final defense

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

 

Xiaojun Sun

Advisor: Priyank Kalla

 

 

Word-level Abstractions for Sequential Design Verification using Algebraic Geometry

 

 

Formal verification of hardware designs has become an essential component of the overall system design flow. The designs are generally modeled as finite state machines, on which property and equivalence checking problems are solved for verification. Reachability analysis forms the core of these techniques. However, increasing size and complexity of the circuits causes the state explosion problem. Abstraction is key to tackle the scalability challenge.

This dissertation presents new techniques for word-level abstraction with applications in sequential design verification. By bundling together k bit-level state-variables into one word-level constraint expression, the state-space is construed as solutions (variety) to a set of polynomial constraints (ideal), modeled over the finite (Galois) field of 2^k elements. Subsequently, techniques from algebraic geometry — notable, Groebner basis theory and technology — are researched to perform reachability analysis and verification of sequential circuits. This approach adds a `”word-level dimension” to state-space abstraction and verification to make the process more efficient.

While algebraic geometry provides powerful abstraction and reasoning capabilities, the algorithms exhibit high computational complexity. In the dissertation, we show that by analyzing the constraints, it is possible to obtain more insights about the polynomial ideals, which can be exploited to overcome the complexity. Using our algorithm design and implementations, we demonstrate how to perform reachability analysis of finite-state machines purely at the word-level. Using this concept, we perform scalable verification of sequential arithmetic circuits. As contemporary approaches make use of resolution proofs and unsatisfiable cores for state-space abstraction, we introduce the algebraic geometry analog of unsatisfiable cores, and present algorithms to extract and refine unsatisfiable cores of polynomial ideals. Experiments are performed to demonstrate the efficacy of our approaches.

 

 

 

Friday December 16, 2016

12:30-2:30 PM, ECE conference room

Merrill Engineering Building (MEB) room 3235

The public is invited

Barun Gupta PhD final defense

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

Barun Gupta

Advisor: Ajay Nahata

 

 

CONTROLLING PROPAGATION PROPERTIES OF SURFACE PLASMON POLARITON AT TERAHERTZ FREQUENCY

 

Despite great scientific exploration since 1900’s, the terahertz range is one of the least explored regions of electromagnetic spectrum today. In the field of plasmonics, texturing and patterning allows for control over electromagnetic waves bound to the interface between a metal and the adjacent dielectric medium. These surface plasmon-polaritons (SPPs) display unique dispersion characteristics that depend upon the plasma frequency of the medium. In the long wavelength regime, where metals are highly conductive, such texturing can create an effective medium that can be characterized by an effective plasma frequency that is determined by the geometrical parameters of the surface structure. The terahertz (THz) spectral range offers unique opportunities to utilize such materials. While there has been significant work on developing coherent sources and detectors, relatively few other device technologies currently exist. A major issue that has constrained this development is the fact that most conventional dielectrics and semiconductors are highly lossy in this spectral range. Since metals are highly conductive, SPPs experience very low propagation loss when air acts as the adjacent dielectric medium.

                This thesis describes a number of terahertz plasmonic devices, both passive and active, fabricated using different techniques. As an example, inkjet printing is exploited for fabricating two-dimensional plasmonic devices. In this case, we demonstrated the terahertz plasmonic structures in which the conductivity of the metallic film is varied spatially in order to further control the plasmonic response. Using a commercially available inkjet printers, in which one cartridge is filled with conductive silver ink and a second cartridge is filled with resistive carbon ink, computer generated drawings of plasmonic structures are printed in which the individual printed dots can have differing amounts of the two inks, thereby creating a spatial variation in the conductivity. The silver ink has a DC conductivity that is only a factor of six lower than bulk silver, while the carbon ink acts as a lossy dielectric at THz frequencies. Both inks sinter at room temperature immediately after contact with the plastic film. Using a periodic array of subwavelength apertures as a test structure, patterns printed with different fractional amounts of the two inks show dramatically different enhanced optical transmission properties. These differences arise from changes in the propagation loss properties as a function of conductivity. This data is used to design and fabricate aperture arrays in which the conductivity varies spatially. The resulting plasmonic effect is found to dramatically alter the spatial beam profile of the transmitted THz radiation, as measured by THz imaging. These plasmonic devices are passive devices.

The inkjet printing technique is limited to the two-dimensional structurers. In order to expand the capability of printing complex terahertz devices, which cannot otherwise be fabricated using standard fabrication techniques, we employed 3D printing. This technique is an additive manufacturing approach, which allows for the fabrication of complex terahertz devices using polymers. The printed structures are then coated with ~ 1 µm of gold on all sides, in order to make it a plasmonic device. Using this printing methodology, we fabricated both planar and non-planar terahertz waveguide devices, including 3D bends, 3D y-splitters and curved waveguides. For the purposes of comparison, we fabricated terahertz waveguide devices and compared them with the standard waveguide devices fabricated using laser ablation techniques with stainless steel films. We find excellent agreement between these two types of devices. At a stage where THz technology is still maturing, the development of devices where the propagation properties can be easily modulated holds great promise for the development of terahertz optoelectronic devices.

In the realm of active plasmonic devices, a wide range of innovative approaches have been developed utilizing a variety of materials including liquid crystals semiconductors, liquid metals, photochromic and electrochromic molecules and phase-change materials. One of the most heavily studied phase change materials for active plasmonic and metamaterial device implementations is vanadium dioxide, VO2, which undergoes a thermally-driven metal–insulator transition near room temperature associated with a structural change in its crystal symmetry. Phase transitions can lead to a variety of different macroscopic effects, which may be useful for active optical applications. As an example, shape memory alloys (SMAs) can be thermally cycled between different physical geometries. As an example, Nitinol, a nickel-titanium alloy, has been shown to be associated with a transformation between the martensite phase below the transition temperature and the austenite phase above the transition temperature. The two most commonly used approaches to control these transitions are referred to as one-way memory and two-way memory. In the former approach, an SMA that has been deformed returns to its original shape after being heated.  This is most commonly demonstrated using wires, though numerous applications utilizing thin metal foils have also been shown. Two-way memory requires that the SMA undergo specific thermo-mechanical treatments, commonly referred to as training procedures, in order to thermally cycle between two different alloy geometries.

We discuss the use of SMAs for terahertz (THz) plasmonics that allows for switching between different physical geometries corresponding to different electromagnetic responses. We use Nitinol, a metal alloy of nickel and titanium composed of approximately equal atomic percentages, as the SMA medium that is structured to give the desired electromagnetic response. Nitinol has a DC conductivity of ~1.25 x 106 S/m for both phases which is similar to the value for stainless steel, making it well suited for THz plasmonic applications. As an SMA, it undergoes a structural transition between the martensite phase to the austentite phase that is bistable and reproducible at temperatures that are only slightly above room temperature. Using a two-way training protocol that we developed, we created samples that transition between either a one-dimensional (1D) or two-dimensional (2D) sinusoidally corrugated geometry and a flat substrate. In order to observe a plasmonic response, the foils are patterned either with a periodic array of subwavelength apertures or a single aperture and their transmission properties are measured using THz time-domain spectroscopy

Friday December 16, 2016

3-5 PM, ECE conference room

Merrill Engineering Building (MEB) room 2109

The public is invited

Shashank Pandey PhD final defense 12/15/2016

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

 

Shashank Pandey

Advisor: Ajay Nahata

 

 

Terahertz Plasmonic Waveguides

 

This dissertation presents work on a new class of terahertz (THz) waveguides based on structured metal geometries. The waveguides are designed with the core idea that adoption of planar layout in fabrication can lead to exponential growth in device capabilities, analogous to the growth in device capabilities based in electronics. From a functional point of view, the waveguides rely upon propagation of surface waves along the surface of metals. This approach is preferred, since dielectrics tend to be lossy at THz and the loss parameters scales almost quadratically with frequency for most dielectrics. The loss in propagating wave is minimized by utilizing metals, which are highly conducting at THz frequencies. Structuring the metal surface with periodic array of apertures of sub-wavelength dimension allows bound surface wave to propagate as the wave can evanescently decay into the metal. This phenomenon is referred as the coupling of propagating wave to surface plasmon polariton (SPP) like mode at the interface of structured metal surface and air. Thus, these propagating THz waves are simply surface plasmon-polaritons (SPPs) . Similarly, complimentary structures that do not perforate the metal, but rather stand on the metal surface also support SPPs. The wavelength of SPPs can be controlled by changing the dimension of these apertures/structures, since the dispersion relationship of the medium depends on the geometrical size. This engineering capability has been exploited in creating all the waveguides presented in this thesis. The devices presented are categorized based on the fabrication technique. Each technique is unique in its own regard and can be selected based on functional needs. A commonly adopted process of laser ablation covers a wide set of waveguides presented here. In one of the waveguides fabricated using ablation technique, the role of disorder is discussed. The waveguide with introduction leads to observance of localized mode with spectral and spatial feature like Anderson localized modes of photons. It is the first report of localized mode at THz frequency. 3D rapid prototyping involving 3D printer is used to create waveguides with complex layout that can allow for multi-plane signal routing. This also is the first demonstration of 3D printing in the development of THz devices. In another approach a unique fabrication technique had to be developed to create waveguides mediums with negative index of refraction (NIM) as they require feature sizes which cannot easily be attained using conventional clean room techniques and 3D printing. This new fabrication approach uses a sacrificial layer technique that is used create an effective medium with negative index of refraction and length on the order of tens of wavelength. Again, this happens to be the first demonstration of a waveguide with NIM capability at THz length scales, as well as a figure of merit (FOM) defined in terms of loss parameter that is an order of magnitude better than the previous reported NIM’s in the THz spectral range.

 

 

 

 

Thursday December 15, 2016

3-5 PM, Wiggins Seminar Room

Warnock Engineering Building (WEB) room 2470

The public is invited

 

 

Apratim Majumder PhD final defense 12/8

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

 

Apratim Majumder

Advisor: Rajesh Menon

 

 

Super-Resolution Optical Lithography Beyond the Far-Field Diffraction Limit Using Photochromic Molecules and Absorbance Modulation Optical Lithography

 

Photolithography has been the main driving force behind the growth and progress in the semiconductor industry. However, as the sizes of circuit elements have been shrunk down every few years, the state of the art of patterning ever-small structures has now almost reached its final limit. This limit to the size of the smallest feature that can be patterned using photolithography is imposed by the diffraction limit of light and is generally accepted to be about half the wavelength of the patterning light. In order to push the size of patterned features below 50 nm, a number of expensive methods are being used in the semiconductor industry, such as double patterning, use of deep ultraviolet wavelengths, and similar others, all of which are limited by the increased cost of equipment, complexity of process and are generally accessible by only the select few with sufficient revenue. Thus, there is a need to develop a low-cost, low-energy super-resolution lithography technique that can pattern features with sizes below the diffraction limit of light.

Absorbance Modulation Optical Lithography (AMOL) is a novel technique of super-resolution maskless photolithography that promises to achieve some of these goals. AMOL makes use of a unique family of organic molecules called photochromes that can switch between two isomeric states based on the wavelength of light that the states absorb. Specifically, the type of photochromes used in AMOL switch between a state that is opaque to ultraviolet (UV) light when absorbing a long wavelength photon (of wavelength λ2) and a state that is transparent to UV when absorbing a short wavelength photon (of wavelength λ1). When a thin layer of this photochromic molecule, termed the absorbance modulation layer (AML) is subjected to simultaneous illumination by a focal spot at λ1 and a ring shaped spot at λ2, it is rendered opaque everywhere except at very close to the center of the optical node in the ring shaped λ2 spot. This competing behavior of the absorbance of the layer to the two wavelengths and the state transitions allows only λ1 photons to penetrate through the λ2 node, creating a nanoscale illumination spot, the dimensions of which are far below the diffraction limit. A recording medium placed under this layer, such as photoresist, can record this illumination. Although the two beams themselves are inherently limited in size by the diffraction limit of the optical system used, the final nanoscale spot that is recorded is not diffraction limited, but controlled by the chemistry of the AML and the ratio of intensities of the two beams.

In this thesis, a number of issues related to the development of AMOL as a cost effective super-resolution photolithography process are addressed. Firstly, an improvement to the AMOL process is affected by the removal of a barrier layer that was present in previous demonstrations in between the AML and the photoresist. This is achieved by investigating different photoresist combinations and identifying a compatible resist-AML combination. Secondly, experimental verification of the AMOL feature-scaling trend is presented. Such an investigation is important to the characterization of any lithography method. Next, a comprehensive model to simulate the AMOL process is constructed using finite element method based full electromagnetic wave solutions. This model and accompanying simulation results present an insight to the effect of various illumination and AML material properties on the performance of AMOL. A couple of methods to realize AMOL patterning at very low light intensity levels are also demonstrated with both simulation and experimental verifications. Lastly, an optical system is described that is capable of extending the AMOL process to patterning aperiodic arbitrary features. 

 

 

Thursday December 8, 2016, 2:00 PM

Sorenson Molecular Bioengineering Building (SMBB) room 2660

The public is invited

 

Fatemeh Koohestan Mahalian MS final defense 12/9

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

MASTER OF SCIENCE

 

by

 

Fatemeh Koohestan Mahalian

Advisor: Neil Cotter

 

 

 

Mathematical Characterization of a Spiking Neuron

 

 

In this thesis, a single neuron with an arbitrary number of inputs is mathematically characterized, and a direct mapping from input firing times to the output firing time is introduced.  Our mapping is referred to as a response surface and, for our model neuron, surface graphs for N-input neurons are hyper-planes intersecting with hyper-cubes where \textit{N} could be any arbitrary positive integer. This thesis answers the question of how to visualize and plot the response to the neuron’s inputs. An accurate mathematical description of a single neuron gives us a tool to design a neural network that produces spikes at desired times, or finding the output spike time for any given pattern of inputs, or deduce the pattern of input spikes that results in a given network output spike pattern by finding intersections of response surfaces for multiple neurons. In our model, spikes are simulated as impulse functions that carry information solely by timing. We use two key ideas to calculate the response surfaces: first, we put the reference time of the synaptic responses at the centers of the triangles, making the math more tractable and symmetric, and second, we shift the output pulse time to zero eliminating the problem of a time reference. Thus, a point on the response surface causes the neuron to spike at time zero and there is no axis of time for the output pulse. We present the response surface graph for a 3-input neuron, with each axis representing a synaptic input’s timing.

 

 

Friday December 9, 2016

11:00 AM

Merrill Engineering Building (MEB) room 2325

The public is invited

 

 

Devavrat Likhite PhD final defense

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

 

Devavrat Likhite

Advisor: Edward DiBella

 

 

Challenges in quantitative cardiovascular magnetic resonance perfusion

 

 

Medical imaging has evolved with leaps and bounds in the last century. Several medical imaging modalities such as X-rays, single photon emission computer tomography (SPECT), positron emission tomography (PET), computer tomography (CT), magnetic resonance imaging (MRI) have developed. However, MRI has a distinct advantage over most of these imaging techniques. MRI does not use ionizing radiation and hence is considered a safer option for non-invasive imaging. However, every imaging modality comes with its set of limitations and challenges. Although quantitative myocardial perfusion MRI has been studied by researchers over a few decades now, it has still not developed into a clinical tool. There is no consensus on the choice of imaging protocol to be used. The scientific community is still divided on the choice of pharmacokinetic model to be used for quantification of myocardial perfusion. In this dissertation, novel techniques were developed and implemented to address few of the challenges faced by fully quantitative myocardial perfusion MRI. We strive to make it more simple and more accurate. It is with the development of such easy-to-use techniques that cardiac perfusion MR will find more and more clinical use. These developments are in a direction to transition quantitative myocardial perfusion MRI from an ‘evolving tool’ to an ‘evolved and matured tool’.

 

 

 

Thursday December 1, 2016

11:00 AM

Imaging and Neurosciences Center (Building 888),

729 Arapeen drive,

Downstairs large conference room

The public is invited

Jotham Vaddaboina Manoranjan PhD final defense

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

 

Jotham Vaddaboina Manoranjan

Advisor: Ken Stevens

 

 

Relative Timing Based Verification and Design with Delay Insensitive Signal Path Modeling with Application for FPGAs

 

 

The relative timing (RT) based asynchronous design methodology has been successfully been used to create ASIC designs that are a process generation ahead of their synchronous counterparts in terms of power, performance and energy. However, while the implementation of RT asynchronous circuits has been dealt with successfully in the ASIC domain, there has been limited exploration of utilizing the design methodology on FPGAs. This dissertation seeks to address the challenges in implementing RT asynchronous circuits on FPGAs. 

Relative Timing uses path based timing constraints to guarantee that a circuit conforms to its behavioral specification. A methodology for the design of glitch free burst-mode asynchronous controllers on FPGAs is presented. Path based timing constraints are implement to ensure circuit functionality. A flow for the modeling of the circuit, extraction of relative timing constraints and implementation of the extracted constraints is presented. Optimizations that enable faster implementation and more robust designs are discussed. 

The dissertation also presents a framework to evaluate and rank relative timing constraint sets for a given circuit. Multiple constraint sets are possible for a single circuit. The constraint sets are evaluated on the basis of robustness of the constraints and conflicts between constraints in the same set. The methodology is used to optimize the extraction of relative timing constraints. 

An FPGA architecture capable of relative timing based digital implementations is designed. Modifications are made to a traditional synchronous FPGA architecture to make it asynchronous capable, while retaining its capability as a fully functional synchronous FPGA. A MIPS design is used to test the FPGA. A performance improvement of 1.7× and a power improvement of 2.3×.

Furthermore, a novel reconfigurable circuit capable of implementing the entire family of 2-phase and 4-phase latch protocols is presented. The circuit is implemented on the IBM Artisan 65nm node and its performance is compared with implementations on a Xilinx Virtex-5 chip that is manufactured on a similar node. A 4× improvement in speed and 2.7× improvement in energy per cycle is achieved.

 

 

 

Wednesday November 30, 2016

12-2 PM, Eccles Boardroom

Warnock Engineering Building (WEB) room 1605

The public is invited

Arslan Majid PhD final defense

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

Arslan Majid

Advisor: Behrouz Farhang

 

 

Secure Communications In Filter-Bank Multi-Carrier

Spread Spectrum Systems

 

 

 

A fundamental characteristic of wireless communications are in their broadcast nature,

which allows accessibility of information without placing restrictions on a user’s location.

However, the ease of accessibility also makes it vulnerable to eavesdropping. This dissertation

considers the security issues of spread spectrum systems and in this context, a secure information transmission system compromised of two main parts is presented. The first component makes use of the principle of reciprocity in frequency-selective wireless channels to derive a pair of keys for two legitimate parties. The proposed key generation algorithm allows for two asynchronous transceivers to derive a pair of similar keys. Moreover, a unique augmentation – called strongest path cancellation (SPC) – is applied to the keys and has been validated through simulation and real-world measurements to significantly boost the security level of the design. In the second part of the secure information transmission system, the concept of artificial noise is introduced to multi-carrier spread spectrum

systems. The keys generated in the first part of the protocol are used as spreading code sequences for the spread spectrum system. Artificial noise is added to further enhance the security of the communication setup. Two different attacks on the proposed security system are evaluated. First, a passive adversary following the same steps as the legitimate users to detect confidential information is considered. The second attack studies a more sophisticated adversary with significant blind detection capabilities.

 

 

 

 

 

Tuesday November 22, 2016

9:00 AM, ECE conference room

Merrill Engineering Building (MEB) room 3235

The public is invited

Suresh Venkatesh PhD final defense

UNIVERSITY OF UTAH

ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT

 

DISSERTATION DEFENSE FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

 

by

Suresh Venkatesh

Advisor: David Schurig

 

 

Metamaterials and their Applications in Imaging

 

Microwave/millimeter-wave imaging systems have become ubiquitous and have found applications in areas like astronomy, bio-medical diagnostics, remote sensing, and security surveillance. These areas have so far relied on conventional imaging devices (employing Nyquist principles) which at best can provide diffraction-limited images. With the advent of metamaterials, unique and extraordinary electromagnetic responses can be achieved which can potentially revolutionize imaging devices. Such extraordinary responses include: negative refraction, strong anisotropy, gradient-index response, perfect absorption, magneto-electric effects (chirality), and many more. When adopted into imaging devices, these response characteristics could potentially: beat diffraction-limits, improve imaging performance or lead to unprecedented control over light propagation. Along with metamaterials, mathematical tools like transformation optics or torsion optics (which leverages Riemannian geometry under the geometrical optics limit) facilitate the design and development of systems with exclusive effects such as invisibility cloaking, perfect and/or aberration-free lensing, near-field magnification, and total control of the polarization field. When metamaterial devices are combined with computational imaging techniques, the resulting systems can exploit apriori information to reach previously unattainable trade-off positions in the space of: image quality, size, weight, power and cost. In this dissertation we present and discuss metamaterial based imaging devices, and associated principles and techniques that achieve such enhanced imaging performance (See Fig.0.1).

In Chapters. [1 & 2], we present a novel “medium-as-device” approach to experimentally demonstrate a metamaterial, perfect-absorber-based focal plane array. The microwave focal plane array was demonstrated both as an intensity detector and as a vector signal detector. The former setup was used to perform interferometric direction finding of RF emitters.

In Chapter. [3], we present a transformation optics designed near-field magnifier, for sub-wavelength imaging. We discuss and present various design parameters and trade-offs associated with such magnifiers. We adopt grid relaxation techniques that result in material properties that are more amenable to implementation. In Chapter. [4], we present a novel “Torsion Optics” design method, leveraging Riemannian geometric concepts, which facilitates the design of devices with gradient chiral material properties, giving an unprecedented control over the polarization field.

In Chapter. [5], we demonstrate a prototype W-band (75 -110 GHz) sparse, syntheticaperture, computational imaging system that leverages intrinsic frequency diversity in the sparse aperture. We also formulate an information-based metric to evaluate the performance of a given image transfer matrix for noise-limited, computational imaging systems. In Chapter. [6], we describe a computationally-fast approach for propagation of vector electromagnetic fields through an axi-symmetric medium (such as a lens) using cylindrical harmonic decomposition techniques. The motivating application is to computational imaging systems, where the forward propagation model must be computed quickly, for real time results. This approach was also applied in the near-field magnifier design and analysis.

In Chapter. [7], as a part of future directions, we exploit all of the above approaches to propose a multi-functional RF system leveraging commercial off-the-shelf integrated circuits. We propose to investigate, in particular, the synergies that result when a single hardware platform can support: focusing-optic-free computational imaging, satellite links on mobile platforms, and electronic targeting of non-lethal force.

 

 

 

Wednesday October 26, 2016

9:30 AM, ECE conference room

Merrill Engineering Building (MEB) room 2109

The public is invited