Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Gearing (3)
- Electromagnetism (2)
- Magnetic devices (2)
- Metamaterials (2)
- Spectroscopy (2)
-
- Terahertz spectroscopy (2)
- Topological photonics (2)
- Adversarial Example (1)
- Arrayed sensor (1)
- Atmosphere (1)
- Atomic spectroscopy -- Mathematical models (1)
- CIFAR10 (1)
- CNN (1)
- Chemical stimulation (1)
- Complex Light (1)
- Convolution Neural Network (1)
- Electrically small antennas (1)
- Electrodynamics -- Mathematical models (1)
- Electrolytic cells (1)
- Electromagnetic fields (1)
- Electromagnetic waves -- Mathematical models (1)
- Explosives -- Detection -- Technique (1)
- Explosives -- Nondestructive testing (1)
- Graphene nanoplatelets (1)
- Hyperbolic metasurface (1)
- Image Recognition (1)
- Kerr Effect (1)
- Lagrange equations (1)
- Laser (1)
- Lidar (1)
Articles 1 - 16 of 16
Full-Text Articles in Engineering
Design And Analysis Of High Performance Magnetic Gears For Magnetomechanical Thrusters, Ho Yin Wong
Design And Analysis Of High Performance Magnetic Gears For Magnetomechanical Thrusters, Ho Yin Wong
Dissertations and Theses
This dissertation is devoted to investigating the performance potential of coaxial radial flux modulating magnetic gears for use in propulsive thruster applications. The research has focused on studying magnetic gear designs suitable for use in electric aircraft drivetrains and electric boat thrusters. Consequent pole, flux concentration and Halbach rotor magnetic gear typologies have been analyzed and compared with respect to their torque density performance for the first time. It is shown that the Halbach rotor magnetic gear holds the greatest potential with respect to achieving volumetric and mass torque densities parity with an equivalent mechanical gear.
A high volumetric torque …
Topological Photonic Metasurfaces For Light Manipulation And Strong Light-Matter Interaction, Svetlana Kiriushechkina
Topological Photonic Metasurfaces For Light Manipulation And Strong Light-Matter Interaction, Svetlana Kiriushechkina
Dissertations and Theses
High-resolution nanopatterning techniques, such as electron beam lithography, extended opportunities for implementation of the various designs of photonic structures which exhibit exciting physical phenomena in the optical domain. A straightforward fabrication of on-slab nanostructures is advantageous for integration with various photonic on-chip devices. Last decade all-dielectric periodic nanostructures (photonic metasurfaces) boost a growth of novel optical technologies, from ultra-sensitive detectors to compact beam structured lasers. Moreover, they represent one of the most promising platforms in which topological phases can be explored and exploited.
Topological photonic structures attract a significant interest owing to their outstanding properties such as a resilience to …
Design And Experimental Observation Of Topological States In Photonic Metasurfaces, Anton Vakulenko
Design And Experimental Observation Of Topological States In Photonic Metasurfaces, Anton Vakulenko
Dissertations and Theses
Topological phases in photonics attract a lot of attention due to their unique properties which allow controlling optical coupling and electromagnetic field distributions in nanostructures. Diverse phenomena supported by photonic topological structures include robust scatter-free waveguiding, an extreme confinement of light, lasing and strong coupling with novel low- dimensional materials. A very convenient integration with on-chip optical devices and also with quantum dots or monolayers of van der Waals materials promise even brighter future for photonic topological insulators as a useful platform for innovative photonic and compact quantum devices.
In the course of my dissertation work, I investigated topological structures …
Nonlinear And Time-Modulated Metamaterials: Applications At Microwave Frequencies, Hady Mohammed Saied Sayed Moussa
Nonlinear And Time-Modulated Metamaterials: Applications At Microwave Frequencies, Hady Mohammed Saied Sayed Moussa
Dissertations and Theses
Metamaterials (the Greek prefix meta, means beyond) are artificially structured materials that interact with the incoming waves in extraordinary ways, beyond the properties of natural materials, yielding unusual and exotic electromagnetics phenomena. By careful engineering of the material properties, invoking nonlinear elements and/or time-modulating some of the material parameters, linearity and/or time-invariance can be broken in metamaterials, enabling extraordinary wave phenomena that open opportunities for the microwave engineering community, including the creation of nonreciprocal devices, frequency conversion, and more. In this dissertation, we explore, investigate, design, and fabricate metamaterials that open new applications for nonlinearity-based and time-varying devices, particularly in …
An Investigation Into Magnetic Gears And Magnetic Springs For Marine Hydrokinetic Power Generators, Hossein Baninajar
An Investigation Into Magnetic Gears And Magnetic Springs For Marine Hydrokinetic Power Generators, Hossein Baninajar
Dissertations and Theses
Marine hydrokinetic generators often use mechanical gears to convert the low-speed motion into the high-speed rotary motion that is required for conventional electrical generators. While mechanical gearboxes have a high torque density and can reach high efficiencies, they suffer from serious reliability issues. Recently, magnetic gearing technology has been proposed as a means of making hydrokinetic generators more reliable. As magnetic gears use magnetic field modulation to create speed change, they offer a high reliability, nonfriction, power transmission mechanism that limits the wear to only the bearings and makes the magnetic gears almost maintenance-free. During an over-torque condition, a magnetic …
Wave Engineering In Time Modulated, Nonlinear, And Anisotropic Metamaterials, Ahmed Mekawy
Wave Engineering In Time Modulated, Nonlinear, And Anisotropic Metamaterials, Ahmed Mekawy
Dissertations and Theses
Leveraging wave matter interactions is central to a myriad of electromagnetic wave-based applications. During the past decades, research on extreme wave manipulation has been revolutionized by artificially engineered materials (metamaterials) and by adding new aspects to the wave-matter interactions that showed intriguing results inaccessible in conventional linear, time invariant (LTI), passive and isotropic media. In this work, I will explore, numerically and experimentally, the possibility of realizing devices that perform beyond or close to their fundamental LTI limitations by adding periodic modulation, nonlinearity, and gain. I will demonstrate these concepts at radio frequencies (RF) and at optical frequencies. Specifically, at …
Nonlinear Light - Matter Interactions Of Ultrafast High Intensity Laser Pulses, Henry Meyer
Nonlinear Light - Matter Interactions Of Ultrafast High Intensity Laser Pulses, Henry Meyer
Dissertations and Theses
This thesis focuses on the key nonlinear optical effects that arise from the interactions of intense ultrafast laser pulses with various states of matter. These interactions involve electronic and molecular states and yield new information on the underlying fundamental processes that govern the molecular world. Modern day lasers offer ultrashort pulses, high intensities, and complex polarizations and wavefronts. These extreme conditions have profound effect on the optical properties and behaviors of electronic and molecular states within a material. The changes in these mechanisms effect generation of nonlinear optics, such supercontinuum (SC), stimulated Raman (SRS), self-focusing and filamentation, conical emission (CE), …
Development Of Light Actuated Chemical Delivery Platform On A 2-D Array Of Micropore Structure, Hojjat Rostami Azmand, Hojjat Rostami Azmand
Development Of Light Actuated Chemical Delivery Platform On A 2-D Array Of Micropore Structure, Hojjat Rostami Azmand, Hojjat Rostami Azmand
Dissertations and Theses
Localized chemical delivery plays an essential role in the fundamental information transfers within biological systems. Thus, the ability to mimic the natural chemical signal modulation would provide significant contributions to understand the functional signaling pathway of biological cells and develop new prosthetic devices for neurological disorders. In this paper, we demonstrate a light-controlled hydrogel platform that can be used for localized chemical delivery in a high spatial resolution. By utilizing the photothermal behavior of graphene-hydrogel composites confined within micron-sized fluidic channels, patterned light illumination creates the parallel and independent actuation of chemical release in a group of fluidic ports. The …
Innovative Applications Of Laser Remote Sensing Of Gases, Aerosols And Wind, Adrian Diaz Fortich
Innovative Applications Of Laser Remote Sensing Of Gases, Aerosols And Wind, Adrian Diaz Fortich
Dissertations and Theses
Over the years, a major component of the research carried out at the Optical Remote Sensing Laboratory of the City College of New York has been on active sensing technologies and their different applications in atmospheric studies. This thesis builds upon and looks to further advance this field by demonstrating innovative applications of laser remote sensing technologies for studies involving trace gases, aerosol particles and wind; which are key components of the Earth’s atmosphere. First, we present the demonstration of gas concentration measurements using a quantum cascade laser open path system with characteristics that make it promising for mobile and/or …
Design And Performance Evaluation Of Linear And Axial-Flux Magnetic Gears, Mojtaba Bahrami Kouhshahi
Design And Performance Evaluation Of Linear And Axial-Flux Magnetic Gears, Mojtaba Bahrami Kouhshahi
Dissertations and Theses
The conversion from low speed to high speed and vice versa in various forms, including rotary and linear motion, is a requirement for a wide range of applications. For example, wind power generation requires a conversion of low speed rotation of turbine blades to high speed generator rotation, and ocean wave power generation is achievable by conversion of low speed linear motion to either high speed rotation or high speed linear motion. Mechanical gearboxes, hydraulic and pneumatic actuators are commonly used to achieve these conversions. However, these systems suffer from reliability issues, high maintenance requirements, noise, and lack of overload …
Understanding Adversarial Training: Improve Image Recognition Accuracy Of Convolution Neural Network, Naoki Ishibashi
Understanding Adversarial Training: Improve Image Recognition Accuracy Of Convolution Neural Network, Naoki Ishibashi
Dissertations and Theses
Traditional methods of computer vision and machine learning cannot match human performance on tasks such as the recognition of handwritten digits. Recently many researchers work on Convolution Neural Network for image recognition, and get results as good as human being. Additionally, Image recognition task is getting more popular and high demand to apply to other fields, but also there are still many problems to utilize in everyday life. One of these problems is that several machine learning models, including neural networks, consistently misclassify adversarial examples—inputs formed by applying small but intentionally worst-case perturbations to examples from the dataset, such that …
Physics-Based Imaging Methods For Terahertz Nondestructive Evaluation Applications, Gabriel Paul Kniffin
Physics-Based Imaging Methods For Terahertz Nondestructive Evaluation Applications, Gabriel Paul Kniffin
Dissertations and Theses
Lying between the microwave and far infrared (IR) regions, the "terahertz gap" is a relatively unexplored frequency band in the electromagnetic spectrum that exhibits a unique combination of properties from its neighbors. Like in IR, many materials have characteristic absorption spectra in the terahertz (THz) band, facilitating the spectroscopic "fingerprinting" of compounds such as drugs and explosives. In addition, non-polar dielectric materials such as clothing, paper, and plastic are transparent to THz, just as they are to microwaves and millimeter waves. These factors, combined with sub-millimeter wavelengths and non-ionizing energy levels, makes sensing in the THz band uniquely suited for …
Optics And Spectroscopy In Massive Electrodynamic Theory, Adam Caccavano
Optics And Spectroscopy In Massive Electrodynamic Theory, Adam Caccavano
Dissertations and Theses
The kinematics and dynamics for plane wave optics are derived for a massive electrodynamic field by utilizing Proca's theory. Atomic spectroscopy is also examined, with the focus on the 21 cm radiation due to the hyperfine structure of hydrogen. The modifications to Snell's Law, the Fresnel formulas, and the 21 cm radiation are shown to reduce to the familiar expressions in the limit of zero photon mass.
3-D Terahertz Synthetic-Aperture Imaging And Spectroscopy, Samuel C. Henry
3-D Terahertz Synthetic-Aperture Imaging And Spectroscopy, Samuel C. Henry
Dissertations and Theses
Terahertz (THz) wavelengths have attracted recent interest in multiple disciplines within engineering and science. Situated between the infrared and the microwave region of the electromagnetic spectrum, THz energy can propagate through non-polar materials such as clothing or packaging layers. Moreover, many chemical compounds, including explosives and many drugs, reveal strong absorption signatures in the THz range. For these reasons, THz wavelengths have great potential for non-destructive evaluation and explosive detection. Three-dimensional (3-D) reflection imaging with considerable depth resolution is also possible using pulsed THz systems. While THz imaging (especially 3-D) systems typically operate in transmission mode, reflection offers the most …
A Lagrangian For A System Of Two Dyons, Rainer Georg Thierauf
A Lagrangian For A System Of Two Dyons, Rainer Georg Thierauf
Dissertations and Theses
Maxwell's equations for the electromagnetic field are symmetrized by introducing magnetic charges into the formalism of electrodynamics. The symmetrized equations are solved for the fields and potentials of point particles. Those potentials, some of which are found to be singular along a line, are used to formulate the Lagrangian for a system of two dyons (particles with both electric and magnetic charge). The equations of motion are derived from the Lagrangian. It is shown that the dimensionality constants k and k * , which we r e introduced to define the units of the electromagnetic fields, have to be equal …
Effects On Electrolytic Cells Of Magnetic Fields Applied To Single Electrodes, Craig Allen Cousins
Effects On Electrolytic Cells Of Magnetic Fields Applied To Single Electrodes, Craig Allen Cousins
Dissertations and Theses
The primary goal of this research was to investigate the effects associated with the application of magnetic fields to single electrodes.