Derivation of Universal Error Parameters for Comprehensive Optical Analysis of Parabolic Troughs

A study is presented where potential optical errors in parabolic troughs are divided into two groups: random and nonrandom. It is shown that the intercept factor is a function of both random and nonrandom errors as well as geometric parameters such as concentration ratio and rim angle. Three error parameters, universal to all collector geometries, that is, “universal” error parameters which combine random and nonrandom errors with collector geometric parameters, are derived analytically. The mathematical derivation of these universal error parameters is presented. A numerical technique, a detailed ray-trace computer routine which maps rays from elemental reflector surfaces to the absorber surface, is used to validate the existence of the universal error parameters. The universal error parameters are made up of one universal random error parameter, σ* ( =σC), and two universal nonrandom error parameters, β* ( = βC) and d* (=(dr)y/D). The use of universal error parameters for comprehensive optical analysis of troughs is also presented.

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Optical Analysis of a Heliostat Array With Linked Tracking

Journal of Solar Energy Engineering ◽

10.1115/1.4023593 ◽

2013 ◽

Vol 135 (3) ◽

Cited By ~ 5

Author(s):

M. T. Dunham ◽

R. Kasetty ◽

A. Mathur ◽

W. Lipiński

Keyword(s):

Concentration Ratio ◽

Tracking System ◽

Average Concentration ◽

Solar Concentrator ◽

Optical Performance ◽

Optical Analysis ◽

Optical Efficiency ◽

The North ◽

The Individual ◽

East West

The optical performance of a novel solar concentrator consisting of a 400 spherical heliostat array and a linked two-axis tracking system is analyzed using the Monte Carlo ray-tracing technique. The optical efficiency and concentration ratio are compared for four different heliostat linkage configurations, including linkages of 1 × 1, 1 × 2, 2 × 2, 4 × 4, and 5 × 5 heliostats for 7-hour operation and the selected months of June and December. The optical performance of the concentrator decreases with the increasing number of heliostats in the individual groups due to increasing optical inaccuracies. In June, the best-performing linked configuration, in which 1 heliostat in the east-west direction and 2 heliostats in the north-south direction are linked, provides a monthly-averaged 7-hour optical efficiency and average concentration ratio of 79% and 511 suns, respectively. In December, the optical efficiency and the average concentration ratio decreases to 61% and 315 suns, respectively.

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Optical Analysis of a New Point Focus Fresnel Concentrator

Volume 1: Advances in Solar Buildings and Conservation; Climate Control and the Environment; Alternate Fuels and Infrastructure; ARPA-E; Combined Energy Cycles, CHP, CCHP, and Smart Grids; Concentrating Solar Power; Economic, Environmental, and Policy Aspects of Alternate Energy; Geothermal Energy, Harvesting, Ocean Energy and Other Emerging Technologies; Hydrogen Energy Technologies; Low/Zero Emission Power Plants and Carbon Sequestration; Micro and Nano Technology Applications and Materials ◽

10.1115/es2015-49340 ◽

2015 ◽

Cited By ~ 1

Author(s):

Hany Al-Ansary ◽

Shaker Alaqel ◽

Eldwin Djajadiwinata ◽

Abdullah Mohammed

Keyword(s):

Concentration Ratio ◽

Focal Point ◽

Tracking System ◽

Average Concentration ◽

The Sun ◽

Optical Performance ◽

Optical Analysis ◽

King Saud University ◽

Stirling Engines ◽

Current Design

This study describes preliminary optical analysis performed regarding a new collector called the Point Focus Fresnel Concentrator (PFFC). This collector combines the concepts of the linear Fresnel collector and central receiver systems to form a new concept of a focal point Fresnel concentrator with a dual-axis sun tracking system. It concentrates direct solar radiation using a number of flat mirrors positioned over a rotating frame. The frame tracks the sun in the azimuth direction, while each row of mirrors tracks the sun in the elevation direction, thereby allowing sunlight to be concentrated on the same point above the collector throughout the day. PFFC is considered suitable for a number of applications, such as power generation by concentrating photovoltaics (CPV) and Stirling engines, and process heat applications. In this study, the first attempt to characterize the optical performance of the collector is made. A prototype of the collector has already been built on the campus of King Saud University. It has a total footprint of 9 m2, and includes 900 mirrors, each of which is 7 cm × 7 cm. The receiver has a diameter of 10 cm. Optical performance is studied by ray tracing methods to obtain flux maps and intercept factors of the receiver. Results show that the average concentration ratio is in the order of 220 to 300 suns when mirrors with a 6-mrad optical error are used. For the same mirrors, the highest attainable average intercept factor (0.674) occurs in the winter due to the low particle loading in the atmosphere. When the optical error is reduced to 2 mrad, the average concentration ratio increases to 290 to 400 suns, and the average intercept factor increases to 0.892. In any case, if the current design of PFFC is to be used in conjunction with CPV, a secondary concentrator would be needed to achieve required concentration ratios in the order of 500 suns.

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Optical Analysis of Solar Parabolic Trough Collector with Flat Concentrating Photovoltaic Receiver

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.2396 ◽

2014 ◽

Vol 592-594 ◽

pp. 2396-2403 ◽

Cited By ~ 2

Author(s):

Nikhilesh R Kamnapure ◽

K. Srinivas Reddy

Keyword(s):

Concentration Ratio ◽

Total Error ◽

Analytical Data ◽

Numerical Results ◽

Distribution Model ◽

Local Concentration ◽

Optical Analysis ◽

Parabolic Trough ◽

Parabolic Trough Collector ◽

The Impact

In this paper, an optical analysis of parabolic trough collector with flat concentrating photovoltaic receiver is carried out by utilizing non-uniform intensity distribution model of the solar disk. The optical system simulation tool ASAP is used to analyze the parabolic trough system with single axis tracking having a mirror aperture of 1m and length of 3m. The impact of random errors including slope error, apparent change in sun’s width, tracking errors on the optical performance of trough system is carried out. The errors are assumed to follow Gaussian (normal) distribution and analyzed statistically. It is found that intercept factor increases with rim angle for given total error of 5, 10 and 20 mrad. Geometrical concentration ratio is varied to see the effect on the intercept factor and compared for various error values. The numerical results show that for De-focused performance (L=0.1f) the local concentration ratio value is 23 for the 45° rim angle. Numerical results are compared with the analytical data available in the literature which show good agreement.

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Lectin-Induced RBC Agglutination: Chemical vs. Cryofixation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600002920 ◽

1980 ◽

Vol 38 ◽

pp. 664-665

Author(s):

Dean A. Handley ◽

Lanping A. Sung ◽

Shu Chien

Keyword(s):

Lectin Binding ◽

Freeze Substitution ◽

Electrostatic Charge ◽

Geometric Parameters ◽

Comparative Approach ◽

Chemical Fixation ◽

Cell Surfaces ◽

Minimal Cell ◽

Membrane Stiffness ◽

Cell Contour

RBC agglutination by lectins represents an interactive balance between the attractive (bridging) force due to lectin binding on cell surfaces and disaggregating forces, such as membrane stiffness and electrostatic charge repulsion (1). During agglutination, critical geometric parameters of cell contour and intercellular distance reflect the magnitude of these interactive forces and the size of the bridging macromolecule (2). Valid ultrastructural measurements of these geometric parameters from agglutinated RBC's require preservation with minimal cell distortion. As chemical fixation may adversely influence RBC geometric properties (3), we used chemical fixation and cryofixation (rapid freezing followed by freeze-substitution) as a comparative approach to examine these parameters from RBC agglutinated with Ulex I lectin.

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Reversion Toward the Mean Independently of Regression Toward the Mean

Methodology ◽

10.1027/1614-2241.5.1.3 ◽

2009 ◽

Vol 5 (1) ◽

pp. 3-6 ◽

Cited By ~ 2

Author(s):

Merton S. Krause

Keyword(s):

Random Error ◽

Evaluation Studies ◽

Internal Validity ◽

Intervention Evaluation ◽

Population Mean ◽

Experimental Intervention ◽

Sample Data ◽

The Mean ◽

Regression Toward The Mean

There is another important artifactual contributor to the apparent improvement of persons subjected to an experimental intervention which may be mistaken for regression toward the mean. This is the phenomenon of random error and extreme selection, which does not at all involve the population regression of posttest on pretest scores but involves a quite different and independent reversion of subjects’ scores toward the population mean. These two independent threats to the internal validity of intervention evaluation studies, however, can be detected and differentiated on the sample data of such studies.

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Evaluation of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings by the multi-frequency radio wave method of a slow surface electromagnetic waves

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-8-51-58 ◽

2020 ◽

pp. 51-58

Author(s):

Aleksandr I. Kazmin ◽

Pavel A. Fedjunin

Keyword(s):

Radio Wave ◽

Noise Level ◽

Electromagnetic Waves ◽

Dielectric Materials ◽

Geometric Parameters ◽

Experimental Investigations ◽

Wave Method ◽

Dielectric Coatings ◽

Surface Electromagnetic Waves ◽

Multilayer Dielectric

One of the most important diagnostic problems multilayer dielectric materials and coatings is the development of methods for quantitative interpretation of the checkout results their electrophysical and geometric parameters. The results of a study of the potential informativeness of the multi-frequency radio wave method of surface electromagnetic waves during reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings are presented. The simulation model is presented that makes it possible to evaluate of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings. The model takes into account the values of the electrophysical and geometric parameters of the coating, the noise level in the measurement data and the measurement bandwidth. The results of simulation and experimental investigations of reconstruction of the structure of relative permittivitties and thicknesses of single-layer and double-layer dielectric coatings with different thicknesses, with different values of the standard deviation (RMS) of the noise level in the measured attenuation coefficients of the surface slow electromagnetic wave are presented. Coatings based on the following materials were investigated: polymethyl methacrylate, F-4D PTFE, RO3010. The accuracy of reconstruction of the electrophysical parameters of the layers decreases with an increase in the number of evaluated parameters and an increase in the noise level. The accuracy of the estimates of the electrophysical parameters of the layers also decreases with a decrease in their relative permittivity and thickness. The results of experimental studies confirm the adequacy of the developed simulation model. The presented model allows for a specific measuring complex that implements the multi-frequency radio wave method of surface electromagnetic waves, to quantify the potential possibilities for the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric materials and coatings. Experimental investigations and simulation results of a multilayer dielectric coating demonstrated the theoretical capabilities gained relative error permittivity and thickness of the individual layers with relative error not greater than 10 %, with a measurement bandwidth of 1 GHz and RMS of noise level 0,003–0,004.

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Optical analysis of ink and other contaminants in process waters

TAPPI Journal ◽

10.32964/tj11.8.51 ◽

2012 ◽

Vol 11 (8) ◽

pp. 51-58

Author(s):

ANTTI HAAPALA ◽

MIKA KÖRKKÖ ◽

ELISA KOIVURANTA ◽

JOUKO NIINIMÄKI

Keyword(s):

Optically Active ◽

Process Water ◽

Paper Machine ◽

Optical Analysis ◽

Direct Process ◽

Active Components ◽

Water Contaminants ◽

Dependent Measurement ◽

Measurement Methodology

Analysis methods developed specifically to determine the presence of ink and other optically active components in paper machine white waters or other process effluents are not available. It is generally more interest¬ing to quantify the effect of circulation water contaminants on end products. This study compares optical techniques to quantify the dirt in process water by two methods for test media preparation and measurement: direct process water filtration on a membrane foil and low-grammage sheet formation. The results show that ink content values obtained from various analyses cannot be directly compared because of fundamental issues involving test media preparation and the varied methodologies used to formulate the results, which may be based on different sets of assumptions. The use of brightness, luminosity, and reflectance and the role of scattering measurements as a part of ink content analysis are discussed, along with fine materials retention and measurement media selection. The study concludes with practical tips for case-dependent measurement methodology selection.

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