Engineering Commons^™

Design And Implementation Of Ccny Dc Microgrid Testbed, Mahmoud Saleh, Yusef Esa, Yassine Mhandi, Werner Brandauer, Ahmed Mohamed

Publications and Research

This paper presents the design, control, energy management, and implementation of the City College of New York (CCNY) direct current (DC) microgrid laboratory testbed. This facility was custom designed and implemented by researchers at CCNY with minimal off-the-shelf components to enable significant flexibility and reconfiguration capability. The microgrid consists of renewable energy resources, energy storage system and controllable loads, and can operate in either a grid-connected or an islanded mode. The design steps, requirements, and results of the developed testbed were discussed. Moreover, several operational scenarios were tested. The experimental results verify the applicability and flexibility of the developed microgrid …

Vector Beams For Fundamental Physics And Applications, Giovanni Milione

Dissertations, Theses, and Capstone Projects

Lights salient degrees of freedom are the independent parameters that completely de- scribe an electromagnetic wave (in the paraxial approximation) and include polarization, wavelength, and time. Most recently, lights space degree of freedom has received sig- nificant attention via the sub-discipline of optics that can be referred to as complex light or structured light. The study of complex light is a veritable renaissance of optics; us- ing lights space degree of freedom many classical optics phenomena have been revisited with novel results. In this thesis, a novel form of structured light referred to as vector beams will be investigated. It …

The Design, Fabrication And Characterization Of Integrated Photoconductive Antennas For On-Chip Terahertz Wave Radiation And Detection, Ruben Dario Velasquez Rios

Dissertations, Theses, and Capstone Projects

Terahertz (THz) wave (between 0.1 and 10 THz) is attracting a lot of attention due to its unique properties that are favorable to various applications. These include non-ionizing radiation, better resolution than a microwave, unique spectral absorption, and an ability to propagate through many types of materials. It has been intensively researched in sensing and imaging technology for a wide range of applications in areas such as biology, pharmaceutical, food and drug control, medical science, and security screening. Driven by mostly scientific research interests, the majority of THz systems are more focused on system performance rather than system size, integration, …

Light-Activated Photocurrent Degradation And Self-Healing In Perovskite Solar Cells, Wanyi Nie, Jean-Christophe Blancon, Amanda J. Neukirch, Kannatassen Appavoo, Hsinhan Tsai, Manish Chhowalla, Muhammad A. Alam, Matthew Y. Sfeir, Claudine Katan, Jacky Even, Sergei Tretiak, Jared J. Crochet, Gautam Gupta, Aditya D. Mohite

Publications and Research

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. However, a key challenge is their lack of stability over prolonged solar irradiation. Few studies have investigated the effect of light soaking on hybrid perovskites and have attributed the degradation in the optoelectronic properties to photochemical or field-assisted ion migration. Here we show that the slow photocurrent degradation in thin-film photovoltaic devices is due to the formation of light-activated meta-stable deep-level trap states. However, the devices can self-heal completely by resting them in the dark for <1 min or the degradation can be completely prevented by operating the devices at 0°C. We investigate several physical mechanisms to explain the microscopic origin for the formation of these trap states, among which the creation of small polaronic states involving localized cooperative lattice strain and molecular orientations emerges as a credible microscopic mechanism requiring further detailed studies.

Satellite Retrievals Of Karenia Brevis Harmful Algal Blooms In The West Florida Shelf Using Neural Networks And Comparisons With Other Techniques, Ahmed El-Habashi, Ioannis Ioannou, Michelle Tomlinson, Richard P. Stumpf, Sam Ahmed

Publications and Research

We describe the application of a Neural Network (NN) previously developed by us, to the detection and tracking, of Karenia brevis Harmful Algal Blooms (KB HABs) that plague the coasts of the West Florida Shelf (WFS) using Visible Infrared Imaging Radiometer Suite (VIIRS) satellite observations. Previous approaches for the detection of KB HABs in the WFS primarily used observations from the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS-A) satellite. They depended on the remote sensing reflectance signal at the 678 nm chlorophyll fluorescence band (Rrs678) needed for both the normalized fluorescence height (nFLH) and Red Band Difference algorithms (RBD) currently used. …

Impact Of Clustering Microgrids On Their Stability And Resilience During Blackouts, Mahmoud S. Saleh, Ammar Althaibani, Yusef Esa, Yassine Mhandi, Ahmed Mohamed

Publications and Research

In this paper, the impact of clustering multiple microgrids during blackouts, on their stability and supply availability, will be investigated. Microgrids have the capability of satisfying their emergency loads during blackouts. However, distributed energy resources (DERs)-dominated microgrids are affected by the uncertainty of their input energy supply, e.g. impact of solar irradiance on photovoltaic (PV) output. Moreover, an individual islanded microgrid is prone to instability issues due to large sudden load/generation changes. In order to increase the supply security, and enhance system stability, we propose to use the existing distribution grid infrastructure, if applicable, during blackouts to form microgrid clusters. …

Design And Analysis Of A Single-Camera Omnistereo Sensor For Quadrotor Micro Aerial Vehicles (Mavs), Carlos Jaramillo, Roberto G. Valenti, Ling Guo, Jizhong Xiao

Publications and Research

We describe the design and 3D sensing performance of an omnidirectional stereo (omnistereo) vision system applied to Micro Aerial Vehicles (MAVs). The proposed omnistereo sensor employs a monocular camera that is co-axially aligned with a pair of hyperboloidal mirrors (a vertically-folded catadioptric configuration). We show that this arrangement provides a compact solution for omnidirectional 3D perception while mounted on top of propeller-based MAVs (not capable of large payloads). The theoretical single viewpoint (SVP) constraint helps us derive analytical solutions for the sensor’s projective geometry and generate SVP-compliant panoramic images to compute 3D information from stereo correspondences (in a truly synchronous …

A Novel Compressed Sensing Method For Magnetic Resonance Imaging: Exponential Wavelet Iterative Shrinkage-Thresholding Algorithm With Random Shift, Yudong Zhang, Jiquan Yang, Jianfei Yang, Aijun Liu, Ping Sun

Publications and Research

Aim. It can help improve the hospital throughput to accelerate magnetic resonance imaging (MRI) scanning. Patients will benefit from less waiting time. Task. In the last decade, various rapid MRI techniques on the basis of compressed sensing (CS) were proposed. However, both computation time and reconstruction quality of traditional CS-MRI did not meet the requirement of clinical use.

Method. In this study, a novel method was proposed with the name of exponential wavelet iterative shrinkagethresholding algorithm with random shift (abbreviated as EWISTARS). It is composed of three successful components: (i) exponential wavelet transform, (ii) iterative shrinkage-thresholding algorithm, and (iii) randomshift. …

Band Gap Engineering Of N-Alloyed Ga2o3 Thin Films, Dongyu Song, Li Li, Bingsheng Li, Yu Sui, Aidong Shen

Publications and Research

The authors report the tuning of band gap of GaON ternary alloy in a wide range of 2.75 eV. The samples were prepared by a two-step nitridation method. First, the samples were deposited on 2-inch fused silica substrates by megnetron sputtering with NH3 and Ar gas for 60 minutes. Then they were annealed in NH3 ambience at different temperatures. The optical band gap energies are calculated from transmittance measurements. With the increase of nitridation temperature, the band gap gradually decreases from 4.8 eV to 2.05 eV. X-ray diffraction results indicate that as-deposited amorphous samples can crystallize into monoclinic and hexagonal …