Methods for Retrieval of Ozone Amount, Cloud and Aerosol Optical Depth from Ground-Based Irradiance Measurements : МЕТОДЫ ОПРЕДЕЛЕНИЯ КОЛИЧЕСТВА ОЗОНА, ОПТИЧЕСКОЙ ГЛУБИНЫ ОБЛАКОВ И АЭРОЗОЛЕЙ ПО ДАННЫМ НАЗЕМНЫХ ИЗМЕ

Sztipanov, Milos Stevens Institute of Technology ProQuest Dissertat 2023 해외박사(DDOD)

This dissertation explores the retrieval of ozone amount, aerosol optical depth, and cloud optical depth using radiative transfer, atmospheric physics, machine learning, irradiance meters, and simulations. The first few sections provide introduction to atmospheric physics, radiative transfer, instrumentation, and machine learning before diving into three distinct studies.The first study investigates the variations in the ozone layer (and ozone hole) over Troll research station in Antarctica and compares total ozone column (TOC) amounts retrieved from data collected by the Norwegian Institute for Air Research- Ultraviolet (NILU-UV) irradiance meter and the Ozone Monitoring Instrument (OMI) deployed on NASA’s AURA satellite.This research emphasizes the importance of monitoring the TOC and ozone hole over Antarctica due to the severe ozone depletion caused by human pollution. Ground-based instruments have proven to be useful in complementing satellite observations in monitoring the ozone layer. The study documents and discusses the variations in the ozone layer (and ozone hole), and investigates the possible reasons for differences in TOC amounts between ground-based NILU-UV and satellite-deployed OMI retrievals.The second study provides a straightforward and general algorithm for aerosol optical depth (AOD) retrieval from ground-based irradiance measurements using a NILU-UV instrument.Aerosols affect various aspects of life, including the transfer of radiation, climate, biosphere, and health. An algorithm for AOD retrieval based on irradiance measurements is provided, which can be easily applied, improved, and customized for different instruments and measurement circumstances. The algorithm is demonstrated using a NILU-UV instrument assuming properties of aerosols typically found in coastal urban areas.Finally, the third study proposes a neural network-based machine learning algorithm to determine TOC, radiation modification factor (RMF), and cloud optical depth (COD) using a NILU-UV instrument deployed on the rooftop of the Department of Physics of Stevens Institute of Technology.The findings suggest that the NILU-UV instruments are suitable for monitoring the ozone layer and COD trends, and the proposed method correlates well with the results of the OMI. Overall, this dissertation provides insights into the retrieval of ozone and aerosol optical depth using different methods and tools, which can be useful for monitoring and understanding components of the Earth’s atmosphere.

Haptic feedback system integration for a prototype robotic surgical unit

Desai, Jaydip Stevens Institute of Technology 2013 해외박사(DDOD)

Robotic surgery is computer-assisted surgery and tools used to enhance minimally invasive surgical procedures. Surgical robots provide exceptional control and precision of surgical instruments. Robotic surgery performs complicated and precise tasks to control and manipulate surgical tools but typically, surgeons do not feel any forces and instead can only rely on an imaging system for feedback. Haptic technology can provide sense of touch to the surgeon through the use of force feedback and tactile cues. The aim of the research presented in this study was to test, analyze and process object-instrument interaction forces to provide a haptic feedback experience to the user controlling robotic surgical tools. The goal of this research was to develop a system to be used as a test platform for evaluating and implementing force feedback mechanism using instrument-object interaction and robotics algorithms to process feedback signal to the user controlling surgical tools in real time. The experiment set up includes two Novint Falcon haptic feedback controllers with QUARC software, a Velmex XSlide assembly for an XYZ stage, an Arduino microcontroller with Linear Actuator Board, Firgelli linear actuators to control the surgical tools, forceps end effector, strain gages used for sensing, and data acquisition system to read amplified strain gage signals. Strain gages successfully record the instrument-object interaction forces and provide feedback to the Novint Falcon controllers through Matlab, SIMULINK and the microcontroller board. Experimental analysis includes use of digital force gauge device and hardcore wire to calibrate and measure instrument-object interaction in the range of 0 - 35 N. It shows linearity in output signals when instrument-object interaction occurs. Research proves application of haptic technology in medical robotics by successfully providing force feedback to the user's hand using strain gage technology. It is concluded that haptic technology with strain gage is capable of providing force feedback. Current robotic surgical set-up was limited to provide force feedback when instrument-object interaction occurs but further research on MEMS technology will provide miniaturization of surgical tool with sensor can be used to test force feedback mechanism during robotic surgery on animals.

Is new product development the solution to a crisis or is crisis the solution to new product development?

Samra, Yassir M Stevens Institute of Technology 2005 해외박사(DDOD)

Crises often have debilitating effects on organizations. At such a critical turning point, the new product development team, as a part of the organization, is under pressure to develop successful new products to deliver the organization from the crisis. But what factors are more effective during a crisis? The scholarship has identified several factors that are associated with project outcomes but has yet to observe these factors in a crisis setting. The purpose of this dissertation is to identify factors that are common to both the NPD and organizational crisis response scholarship and test these factors in a sample of managers from a wide cross section of technology-based companies. By studying the practices of 67 NPD teams in a crisis setting and 62 NPD teams in a low crisis setting (N = 129), we found that speed to market can improve new product success rates under times of crisis. In addition, we found a quadratic effect under times of low crisis. The other factors in the model which include team improvisation, top management involvement, and team communications were significantly associated with crisis but did not have any significant effect on new product success.

Theoretical investigations for shot noise in correlated resonant tunneling through a quantum coupled system

Djuric, Ivana M Stevens Institute of Technology 2005 해외박사(DDOD)

In recent years the study of shot noise in mesoscopic quantum systems has become an emerging topic in mesoscopic physics, because a measurement of shot noise can reveal more information of transport properties which is not available through the conductance measurement alone [1, 2]. Besides, special interest has recently been put on the investigation of tunneling through a two-level system (TLS), when the coherent coupling between the two levels is presented. It is quite desirable to find a way of evaluating current correlation in arbitrary bias-voltages, particularly in moderately small bias-voltage region, where the coherence plays a more prominent role in quantum tunneling processes. Accordingly, the purpose of this work is to develop a general scheme to study the quantum shot noise spectrum of coupled small quantum systems based on the recently established quantum rate equations with a bias-voltage and temperature dependent version [22]. Actually, a numerical method, named generation-recombination approach, was established for analysis of shot noise in two-terminal single-electron tunneling devices with the classical rate equation (classical shot noise) in Refs. [23, 24, 25]. These earlier papers proposed a powerful method to evaluate the double-time current correlation function by switching the time-dependent current to a time evolution propagator of the density matrices in a consistent way. In the present work, we will modify this traditional approach to suit the underlying quantum rate equations for properly accounting for the quantum coherence effects, i.e., the nondiagonal elements of density matrix, in calculation of quantum shot noise and develop a tractable computation technique in matrix form. As applications, analytical and numerical investigations have been given in detail for three cases: (1) electron tunneling through a quantum dot connected to ferromagnetic leads with intradot spin-flip scattering, (2) spinless fermions tunneling through seriesly coupled quantum dots, and (3) side-coupled quantum dots, focusing on the shot noise as functions of bias-voltage and frequency. (Abstract shortened by UMI.).

An optimal and cost effective optical performance monitoring (OPM) methodology for an all-optical wavelength routed meshed network

Dorleus, Joseph Alphonse Raoul Stevens Institute of Technology 2005 해외박사(DDOD)

All-Optical Networks are the next generation optical networks that will provide a transport mechanism to deliver a variety of users' data telecommunications and quality of service requirements reliably. Their desirable features such as transparency to the information transfer, enormous bandwidth make them a natural choice among telecommunications service providers. However, all-optical networks' wide commercial deployments are hampered by their inadequacy to provide a cost effective optical performance monitoring of the user's data and the negotiated quality of service requirements. Many optical monitoring techniques designed to measure the optical signal quality have been proposed in the literature. All of the proposed methods require either the use of monitoring devices by tapping into a portion of the optical fiber link to estimate optical power levels, optical signal to noise ratio, or performing Q-factor measurements using histograms, among other methods. Most of these techniques require the use of a great deal of electronic processing at the device level, or some level of access to the information bit stream in the core network. As a result, these optical monitoring methods hinder transparency to data bit rate, code or modulation format as well as the speed of the information transfer. Additionally, all the currently proposed optical performance monitoring approaches limits to point-to-point physical layer monitoring, ignoring the rest of the networks. In this dissertation, we propose to perform analysis of an optical monitoring methodology that incorporates the user access layer, the physical layer and the network layer on integrated optical meshed network architecture. We investigated the performance parameters that need to be monitored at each layer. We modeled a wavelength routed transparent network, and performed cost optimization at three separate layers; the optical transport layer, the multiplex layer, and the optical channel layer. We then determined the optimum transparency reach that minimizes network equipment cost, node cost, and link cost based on random traffic distributions. We performed physical layer performance simulations of WDM systems and optical meshed-networks to collect statistics on optical performance parameters that most affect the signal quality in the present of noise, distortion, and non-linearity and during network failures. We performed analysis and evaluation of these parameters using physical layer network simulation of WDM systems and optical fiber transmission systems under various optical amplifier noise conditions. Simulation results of our optical performance analysis architecture have shown greater improvement in accuracy in monitoring and measurements of the performance parameters, in addition to being more cost effective compared to other proposed optical performance monitoring approaches.

Assessing NASA strategic project leadership in an era of 'better, faster, cheaper'

Sauser, Brian J Stevens Institute of Technology 2005 해외박사(DDOD)

Assessing NASA Strategic Project Leadership in an Era of "Better, Faster, Cheaper" The purpose of this study was to develop a better understanding of the management of strategic system projects (and programs) at NASA and, in particular, what makes such projects successful or not in an era of "better, faster, cheaper" (BFC). Such projects are typically characterized by advanced technology, new types of missions, complex integration of hardware and software systems, and inflexible time frames that are often dictated by "launch windows." To analyze strategic projects, this investigation used the framework of Strategic Project LeadershipRTM (SPL)1 correlated to the success of a systems development project through case study research. Four NASA projects were investigated that were managed as BFC projects. Two of them were successes (Mars Pathfinder and Lunar Prospector), and two failures (CONTOUR and Mars Climate Orbiter). The objectives were to (1) develop a better conceptual understanding of strategic system innovation through the study of BFC projects, (2) understand how SPL can describe BFC projects, and (3) provide feedback, recommendations, and lessons learned to NASA and the aerospace industry on potential success criteria for BFC projects. Of particular interest in this study was the analysis of fit between project type and the appropriate project management style. This research found that there was a good fit between project type and project management style in the two successful projects while in the unsuccessful projects this fit was apparently missing. It seems there is a need to develop a specific NASA framework to assess a project's risk and its appropriate project management style. 1Shenhar, A. J. (2004) "Strategic Project Leadership RTM Toward A Strategic Approach to Project Management." Accepted for publication in R&D Management.

Holographic control of motive shape in plasmonic nanogap arrays

Zhang, Xi Stevens Institute of Technology 2013 해외박사(DDOD)

Plasmonic nanostructures have attracted increasing research attention due to their unique ability to generate surface plasmons and to concentrate the electromagnetic energy well below the diraction limit, leading to novel applications such as chemical sensing, photovoltaic devices with enhanced eciency, and miniaturizing of on-chip photonic circuits. Clearly, those applications will benet tremendously from the advent of novel high-throughput wafer-scale nanofabrication techniques. To this end, holographic lithography is an appealing low-cost approach to create nanopattern at wafer scale without the need for scanning of electron or ion beams, prefabricated masks, pre-patterned wafers, or atomic layer deposition. The goal of this thesis was therefore to explore if holographic lithography is suitable to create plasmonic nanostructures. In this thesis, I developed a 4-beam holographic lithography system and fabricated various nanoarray templates featuring a large degree of freedom to control pattern shape and size. I demonstrate a novel theoretical approach based on decomposing the interference pattern into groups of sub-functions each representing the sub-lattices of a compound lattice. Basic design rules of the phase and polarization control are presented to show how the degeneracy and spatial positions of these sub-lattices can be controlled in such a way that twin, triplet, and quadruplet motive shapes emerge. The key novelty is the discovery that the compound lattice can be utilized to create arbitrarily small feature sizes well below the diraction limit predicted by the Bragg equation. Beyond theory, I demonstrate experimentally patterning of those motive shapes into polymer lms featuring up to four nanogaps in the unit cell as well as dened electric eld orientation. Polymer templates were transferred into gold nanogap arrays resulting in nanogap features down to 7 nm, which are 70 times smaller than the laser wavelength (488 nm). In addition, the optical resonances of these plasmonic nanostructures have been simulated and compared to transmission measurements, providing further guidance how to engineer plasmonic arrays towards enhancing the light emission from carbon nanotubes. These results extend the utility of high-throughput, wafer-scale holographic lithography into the realm of nanoplasmonics, and open up novel possibilities to fabricate various nanostructures required for plasmonics enabled applications.

Electron scattering contrast in unstained mesoscopic polymers

Chou, Tseng-Ming Stevens Institute of Technology 2002 해외박사(DDOD)

Due to the fact that polymers scatter electrons weakly, heavy-element staining is usually required when preparing polymer specimens for transmission electron microscopy (TEM). Staining enhances image contrast but can introduce artifacts. These artifacts are especially problematic in high-resolution imaging of polymer nanostructures and interfaces. This thesis begins with an experimental demonstration of such staining artifacts. Phase-contrast imaging is one alternative method in TEM for imaging unstained polymer structures. This thesis compares two phase-contrast imaging techniques: off-axis transmission electron holography and focal-series imaging. The focal-series method retrieves the image phase from the recorded image intensity at different values of microscope focus. It can be understood in terms of image transfer theory. Off-axis transmission electron holography retrieves the image phase by interfering the image wave with a reference wave. A field-emission TEM is required, because of its high coherence. Using arborescent graft poly(styrene) nanoparticles as model specimens, phase-contrast images from both methods have been analyzed and compared. Holographic imaging shows significantly higher contrast of unstained polymer samples than does the focal-series method. Holography also provides 3-D information from 2-D projected TEM images when the specimen mean inner potential is known. High-resolution holography has significant opportunity to study nanospecimens like viruses, proteins, and dendritic polymers. This thesis concludes with a discussion of the possibility of using spatially-resolved electron energy-loss spectroscopy, an another alternative method of studying unstained polymer structure using chemical or bonding maps, to image polymer fine structure without staining.

Development of a video technique to study bed load sediment transport

Roarty, Hugh John Stevens Institute of Technology 2001 해외박사(DDOD)

A video technique has been developed to study the motion of individual sediment particles under waves. The technique was developed for moveable bed conditions under waves in the Davidson Laboratory's Large Wave Tank. Experiments were conducted with grain sizes of 1, 2 and 3 mm. All runs were applied to a Shields diagram and accurately predicted the region of motion and no motion. This proves that shear stress is an accurate predictor of grain movement initiation for a flat bed. The individual particle velocities were also measured. An ensemble average of particle velocity with respect to wave phase compared well with Sleath's (1986) expression for instantaneous bed load transport. Particles of this size lead the free stream velocity by approximately 25° and travel at approximately 30% of the free stream fluid velocity. Additional experiments were conducted to study the motion of particles under waves with no intergranular forces affecting the motion of the particles. An equation of motion for a sediment particle under waves, offered by Grant and Madsen (1982), was used to predict the sediment particles acceleration.

Multiuser code-timing acquisition for DS-CDMA systems

Wang, Rensheng Stevens Institute of Technology 2005 해외박사(DDOD)

Multiuser code-timing acquisition, which parallels the well acknowledged research on multiuser detection (e.g., [57] and references therein) for direct-sequence (DS) code-division multiple-access (CDMA) systems, has been receiving increasing interest recently. A multitude of near-far resistant code-timing acquisition techniques have been proposed in the last few years (see [43] [48] [64] [3] [50] [2] [30) [25] [20] [37]). However, most of these techniques assume short or periodic spreading codes, whereby the code sequence periodically repeats itself for every symbol duration. In addition, most existing schemes assume rectangular chip waveforms that are not bandlimited. This is in contrast to bandlimited chip waveforms, such as the square-root raised cosine pulse, that are used in real CDMA systems. In this dissertation, we have made an intensive study on the code-timing estimation problem for asynchronous DS-CDMA systems and proposed a number of codetiming acquisition schemes from different perspectives. Code acquisition is essentially to determine the propagation path delays between transmitters and receivers, which are prerequisite for all the multiuser detection and estimation schemes. We have considered both time-domain filterbank based and frequency-domain filterbank based approaches. We have studied both training-based and blind schemes. We have developed both decorrelating based and interference resistant methods. We have examined both deterministic multiuser estimator and Large-Sample Maximum Likelihood based single user estimator. In addition, we have investigated the derivation of the lower bound for all unbiased estimators and the efficient implementations with respect to computational complexity. In particular, we have paid close attention to CDMA with bandlimited chip pulse modulation, which is usually neglected by some of the existing multiuser code synchronization schemes assuming rectangular chip waveforms. Note that extending these schemes to deal with bandlimited waveform is in general difficult, due to highly nonlinear complexity. Finally, we have presented the numerical results of all the proposed schemes respectively and evaluated them by comparing with the existing techniques in Monte Carlo simulations.