The long-term goal of the project is to create and justify a reliable mathematical model that expresses the efficiency of geometrical shapes of non-tracking flexible solar panels. However, the amount of solar energy absorbed by a non-tracking flexible solar panel depends on many parameters: the direction of the sun beam, reflected light, and temperature, etc., which would make a complete model mathematically complicated. In the current model, we limit our consideration to the direction of the sunbeam. In order to simulate the exposure of the panel, we describe the trajectory of the Sun and base the model on the mathematical flux that uses the sun rays as the vector field. To be precise, the efficiency of a geometrical panel is defined as the flux density, which is the ratio of the mathematical flux and the surface area. Our current model was evaluated for the latitude of New York City and we determined the efficiency of the optimized at panels, cylindrical panels, and conical panels. The analysis was largely done through geometrical studies and numerical integration with software programs Python, Maple, Mathematica, and MATLAB.
The purpose of this research is to analyze mathematically cylindrical shapes of flexible solar panels and compare their efficiency to the flat panels. The efficiency is defined to be the flux density, which is the ratio of the mathematical flux and the surface area. In addition we describe the trajectory of the Sun at specific locations: the North Pole, The Equator and a geostationary satellite above the Equator. The calculations were performed with software: Maple, Mathematica, and MATLAB.
The purpose of this study is to analyze various surfaces of flexible solar panels and compare them to the traditional at panels mathematically. We evaluated the efficiency based on the integral formulas that involve flux. We performed calculations for flat panels with different positions, a cylindrical panel, conical panels with various opening angles and segments of a spherical panel. Our results indicate that the best efficiency per unit area belongs to particular segments of spherically-shaped panels. In addition, we calculated the optimal opening angle of a cone-shaped panel that maximizes the annual accumulation of the sun radiation per unit area. The considered shapes are presented below with a suggestion for connections of the cells.
Interaction between the tropical ocean and atmosphere produces interannual climate variability dominated by the El Ni˜no Southern Oscillation (ENSO). We perform a Fourier analysis of the El Ni˜no events, which are characterized by positive sea-surface temperature (SST) anomalies. We consider an elementary nonlinear model for the ENSO phenomenon: the time rate of change of the SST depends on the existence of a strong positive feedback in the coupled ocean-atmosphere system, and on a nonlinear mechanism that limits the growth of unstable perturbations. A key element in this model is the inclusion of the effects of equatorially trapped oceanic waves propagating in a closed basin through a time delayed term. Numerical solution reveals solutions that are self-sustained oscillations. The model is extended by including external influences such as annual forcing, global warming, and stochastic effects. We investigate the range of the parameters that will cause drastic qualitative changes in the climate system, i.e. bifurcation.
Lidar daylight measurements are limited by sky background noise (BGN). Reducing the BGN is essential to improve Lidar signal-to-noise ratio (SNR). We report on an optimization technique to improve SNR in a monostatic/biaxial and bistatic Lidar systems by redesigning the geometrical scheme of Lidar receiver. A series of simulations to calculate the overlap area between both transmitter and receiver field of view (FOV) is conducted to determine optimal receiver aperture shapes, locations, and sizes within different lidar ranges. Techniques to vary receiver aperture shape, position, and size to accommodate backscattering signals over a given range, to maximize Lidar SNR, is introduced. At the same short range, numerical results show a better GF of the bistatic compared to the monostatic/biaxial configurations. A complete comparison between monostatic/biaxial and bistatic configurations, for low altitude measurements between 0.1km and 2km, is discussed.
We report on the measurements of aerosol and cloud vertical structure in New York City (NYC) using the first polarization Micro pulse Lidar (MPL) located at the City University of New York (CUNY). MPL operation, setup, data collection and correction will be introduced. Preliminary results and comparison analysis between 2015 and 2016 of cloud vertical structure and the Planetary Boundary Layer (PBL) above NYC will be discussed. An investigation analysis of the impact of NYC rush hour pollution on the level of PBL depth will be introduced using the MPL measurements (such as temporal and spatial trends in aerosol and cloud structure). Applications of the MPL tow-polarization channels will be investigated. Potential future studies and collaborations in protecting NYC against environmental disasters by employing more devices along with MPL real-time data will be emphasized. For pedagogical purposes, a lab module was developed to be implemented in the newly developed undergraduate track in Earth System Science and Environmental Engineering (ESE) at LaGuardia Community College of CUNY (LaGCC), more details will be presented.
KEYWORDS: LIDAR, Polarization, Signal to noise ratio, Receivers, Signal detection, Scattering, Polarizers, Control systems, Phase modulation, Interference (communication)
Recently, there has been significant interest in lidar signal-to-noise ratio (SNR) improvements, particularly for lidar
daytime operations. Previously, we devised in the remote sensing laboratory at the City College of New York a
polarization discrimination technique to maximize lidar detected SNR taking advantage of the natural polarization
properties of scattered skylight radiation to track and minimize detected sky background signal (BGS). This tracking
technique was achieved by rotating, manually, a combination of polarizer and analyzer on both the lidar transmitter and
receiver subsystems, respectively. The polarization orientation at which the minimum BGS occurs, follows the solar
azimuth angle, even for high aerosol loading. This has been confirmed, in our previous work, both theoretically,
assuming single scattering theory, and experimentally. In this paper, a design to automate the polarization discrimination
technique by real time tracking of the azimuth angle to attain the minimum BGS is presented. We introduce a feedback
control system to track the minimum BGS by rotating the detector analyzer and the transmission polarizer
simultaneously to maximize the SNR and attainable lidar ranges, thus achieving the same results as would be done
manually. Analytical results for New York City are summarized and an approach for applying the proposed design
globally is investigated.
We examine the potential, range of application, and limiting factors of a polarization selection technique, recently devised by us, which takes advantage of naturally occurring polarization properties of scattered sky light to minimize the detected sky background signal and which can be used in conjunction with linearly polarized elastic backscatter lidars to maximize lidar receiver SNR. In this approach, a polarization selective lidar receiver is aligned to minimize detected skylight, while the polarization of the transmitted lidar signal is rotated to maintain maximum lidar backscatter signal throughput to the receiver detector, consequently maximizing detected signal to noise ratio. Results presented include lidar elastic backscatter measurements, at 532 nm which show as much as a factor of √10 improvement in signal-to-noise ratio over conventional un-polarized schemes. For vertically pointing lidars, the largest improvements are limited to symmetric early morning and late afternoon hours. For non-vertical scanning lidars, significant improvements are achievable over much more extended time periods, depending on the specific angle between the lidar and solar axes. A theoretical model that simulates the background skylight within the single scattering approximation showed good agreement with measured SNR improvement factors. Diurnally asymmetric improvement factors, sometimes observed, are explained by measured increases in PWV and subsequent modification of aerosol optical depth by dehydration from morning to afternoon. Finally, since the polarization axis follows the solar azimuth angle even for high aerosol loading, as demonstrated using radiative transfer simulations, it is possible to conceive automation of the technique. In addition, it is shown that while multiple scattering reduces the SNR improvement, the orientation of the minimum noise state remains the same.
The impact and potential of a polarization selection technique to reduce sky background noise (BGN) for monostatic elastic backscatter lidar measurements is examined. Taking advantage of naturally occurring polarization patterns in scattered sky light, we devised a polarization discrimination technique in which both the lidar transmitter and receiver track and minimize detected sky background noise while maintaining maximum lidar signal throughput. Lidar elastic backscatter measurements, carried out continuously during daylight hours at 532 nm, with a vertically pointing lidar in an urban atmosphere, show that changes of a factor of 10 in detected sky background noise power can occur between different polarization orientations for large solar zenith angles. This translates to over a factor of three improvement in signal to noise ratios (SNR) over conventional un-polarized schemes, depending on inclination of the lidar axis and the solar angle, with potential corresponding improvements in lidar range for elastic backscatter schemes including Raman and DIAL. The experimental measurements show that the diurnal variations in improved signal to noise ratio, including the impact of relative humidity, are consistent with theoretical estimates employing Radiative Transfer (RT) and using an urban aerosol model based on adjacent and simultaneous CIMEL measurements.
Range and sensitivities of lidar measurements are limited in daytime use by sky background noise (BGN). We report on a polarization technique to reduce the detected sky BGN by making use of the fact that daylight sky noise is polarized by atmospheric scattering to a greater or lesser degree, depending on the solar zenith angle. With suitable rotation of a beam polarizer at the entrance of the detector, the sky noise reaching the detector is minimized. At the same time, the polarization of the outgoing lidar signal is rotated to align the polarizations of both the outgoing and elastically scattered return signals with that of the polarizer in front of the detector. This ensures unhindered passage of lidar returns to the detector while at the same time minimizing detected BGN. Daylight measurements with a vertically oriented elastic backscatter lidar at 532 nanometers show that as much as tenfold improvements in signal to noise ratio (SNR), and consequent improvements in effective lidar range, can be obtained for high solar zenith angles (less for angles closer to the zenith) in typical urban atmospheric conditions. The variations in SNR as a function of different solar angles were found to be consistent with theoretical estimates of the variation of the polarization factor for incoming vertical skylight for an urban atmosphere based on adjacent CIMEL measurements of the atmospheric optical depth over the same period.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.