Comparative Study of Solar Optics for Paraboloidal Concentrators

1980 ◽  
Vol 102 (4) ◽  
pp. 305-315 ◽  
Author(s):  
L. Wen ◽  
L. Huang ◽  
P. Poon ◽  
W. Carley
Keyword(s):  
Flux Distribution ◽  
Computational Method ◽  
Optical Parameters ◽  
Solar Concentrator ◽  
Surface Slope ◽  
Algebraic Form ◽  
Reflector Surface ◽  
Slope Error ◽  
Definition Of ◽  
Limb Darkening

Different analytical methods for computing the flux distribution on the focal plane of a paraboloidal solar concentrator are reviewed. An analytical solution in algebraic form is also derived for an idealized model. The effects resulting from using different assumptions in the definition of optical parameters used in these methodologies are compared and discussed in detail. These parameters include solar irradiance distribution (limb darkening and circumsolar), reflector surface specular spreading, surface slope error, and concentrator pointing inaccuracy. The type of computational method selected for use depends on the maturity of the design and the data available at the time the analysis is made.

scholarly journals Radiative forcing of the desert aerosol at Ouarzazate (Morocco)

2018 ◽  
Vol 37 ◽  
pp. 03004
Author(s):  
Abdelouahid Tahiri ◽  
Mohamed Diouri
Keyword(s):  
Optical Properties ◽  
Atmospheric Aerosol ◽  
Radiative Forcing ◽  
Cloud Formation ◽  
Optical Parameters ◽  
Aerosol Radiative Forcing ◽  
Daily Average ◽  
Definition Of ◽  
Aerosol Radiative

The atmospheric aerosol contributes to the definition of the climate with direct effect, the diffusion and absorption of solar and terrestrial radiations, and indirect, the cloud formation process where aerosols behave as condensation nuclei and alter the optical properties. Satellites and ground-based networks (solar photometers) allow the terrestrial aerosol observation and the determination of impact. Desert aerosol considered among the main types of tropospheric aerosols whose optical property uncertainties are still quite important. The analysis concerns the optical parameters recorded in 2015 at Ouarzazate solar photometric station (AERONET/PHOTONS network, http://aeronet.gsfc.nasa.gov/) close to Saharan zone. The daily average aerosol optical depthτaer at 0.5μm, are relatively high in summer and less degree in spring (from 0.01 to 1.82). Daily average of the Angstrom coefficients α vary between 0.01 and 1.55. The daily average of aerosol radiative forcing at the surface range between -150W/m2 and -10 W/m2 with peaks recorded in summer, characterized locally by large loads of desert aerosol in agreement with the advections of the Southeast of Morocco. Those recorded at the Top of the atmosphere show a variation from -74 W/m2 to +24 W/m2

scholarly journals Elliptically Bent X-Ray Mirrors with Active Temperature Stabilization

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Sheng Yuan ◽  
Matthew Church ◽  
Valeriy V. Yashchuk ◽  
Kenneth A. Goldberg ◽  
Richard S. Celestre ◽  
...  
Keyword(s):  
Laboratory Testing ◽  
High Heat ◽  
Temperature Stabilization ◽  
Surface Slope ◽  
Peltier Element ◽  
X Ray ◽  
Slope Error ◽  
Temperature Controlled ◽  
Active Mirror ◽  
Active Temperature

We present details of design of elliptically bent Kirkpatrick-Baez mirrors developed and successfully used at the advanced light source for submicron focusing. A distinctive feature of the mirror design is an active temperature stabilization based on a Peltier element attached directly to the mirror body. The design and materials have been carefully optimized to provide high heat conductance between the mirror body and substrate. We describe the experimental procedures used when assembling and precisely shaping the mirrors, with special attention paid to laboratory testing of the mirror-temperature stabilization. For this purpose, the temperature dependence of the surface slope profile of a specially fabricated test mirror placed inside a temperature-controlled container was measured. We demonstrate that with active mirror-temperature stabilization, a change of the surrounding temperature by more than 3 K does not noticeably affect the mirror figure. Without temperature stabilization, the rms slope error is changed by approximately 1.5 μrad (primarily defocus) under the same conditions.

Minimum entropy deconvolution and simplicity: A noniterative algorithm

Geophysics ◽  
1985 ◽  
Vol 50 (3) ◽  
pp. 394-413 ◽  
Author(s):  
Carlos A. Cabrelli
Keyword(s):  
Synthetic Data ◽  
Computational Method ◽  
Minimum Entropy ◽  
Autocorrelation Matrix ◽  
Numerical Tests ◽  
Convolution Model ◽  
Single Input ◽  
Definition Of ◽  
Single Matrix ◽  
New Criterion

Minimum entropy deconvolution (MED) is a technique developed by Wiggins (1978) with the purpose of separating the components of a signal, as the convolution model of a smooth wavelet with a series of impulses. The advantage of this method, as compared with traditional methods, is that it obviates strong hypotheses over the components, which require only the simplicity of the output. The degree of simplicity is measured with the Varimax norm for factor analysis. An iterative algorithm for computation of the filter is derived from this norm, having as an outstanding characteristic its stability in presence of noise. Geometrical analysis of the Varimax norm suggests the definition of a new criterion for simplicity: the D norm. In case of multiple inputs, the D norm is obtained through modification of the kurtosis norm. One of the most outstanding characteristics of the new criterion, by comparison with the Varimax norm, is that a noniterative algorithm for computation of the deconvolution filter can be derived from the D norm. This is significant because the standard MED algorithm frequently requires in each iteration the inversion of an autocorrelation matrix whose order is the length of the filter, while the new algorithm derived from the D norm requires the inversion of a single matrix. On the other hand, results of numerical tests, performed jointly with Graciela A. Canziani, show that the new algorithm produces outputs of greater simplicity than those produced by the traditional MED algorithm. These considerations imply that the D criterion yields a new computational method for minimum entropy deconvolution. A section of numerical examples is included, where the results of an extensive simulation study with synthetic data are analyzed. The numerical computations show in all cases a remarkable improvement resulting from use of the D norm. The properties of stability in the presence of noise are preserved as shown in the examples. In the case of a single input, the relation between the D norm and the spiking filter is analyzed (Appendix B).

Optical Analysis of Solar Concentrators Using Photogrammetry Process

2017 ◽  
pp. 175-201
Author(s):  
Safa Skouri ◽  
Salwa Bouadila
Keyword(s):  
Measurement Technique ◽  
Measurement Techniques ◽  
High Impact ◽  
Geometric Errors ◽  
Solar Concentrator ◽  
Optical Analysis ◽  
Optical Efficiency ◽  
Solar Concentrators ◽  
Displacement Error ◽  
Slope Error

As the optical efficiency of solar concentrators has a high impact on its thermal performance. However a qualification method determining the geometrical accuracy of a solar concentrator system is necessary. The purpose of this chapter is to gives an optical analysis of solar concentrator with an imaging process in order to improve the thermal efficiency of the solar concentrator. In this order measurement techniques used to determine geometric errors of the solar concentrating system have been described. Intercept factor, slope error and displacement error have been identified and analyzed. Examples of the intercept factor for concentrator reflector along with optical efficiency has been developed and determined related to the experimental results given by photogrammetry measurement technique.

scholarly journals Verification of optical modelling of sunshape and surface slope error for concentrating solar power systems

Solar Energy ◽  
2020 ◽  
Vol 195 ◽  
pp. 461-474 ◽  
Author(s):  
Ye Wang ◽  
Daniel Potter ◽  
Charles-Alexis Asselineau ◽  
Clotilde Corsi ◽  
Michael Wagner ◽  
...  
Keyword(s):  
Power Systems ◽  
Solar Power ◽  
Surface Slope ◽  
Concentrating Solar Power ◽  
Optical Modelling ◽  
Slope Error

Способ обработки результатов магнитной дефектоскопии для достоверного обнаружения опасных дефектов сплошности в реальном времени

2020 ◽  
pp. 58-64
Author(s):  
А.Н. Печенков
Keyword(s):  
Magnetic Field ◽  
Inverse Problem ◽  
Inverse Problems ◽  
Computer Program ◽  
Real Time ◽  
High Precision ◽  
Computational Method ◽  
On Line ◽  
Definition Of ◽  
Minimization Of Functional

The inverse problems of magnetostatics for defects of a continuum can be formulated in various ways. It is possible to set a task of definition of defects with high precision and permission,or it is possible to limit the task to detection of several types of defects («dangerous» defects) with good probability. At the same time «small» defects will be passed by the computer program. The problem of minimization of functional for both experimental and computational magnetic field differences is the main problem for the solution of any inverse problem, both in on – line (real time), and in off - line modes. Computational method of calculations in real time of the simplified inverse problem, without accumulation of experimental databases is considered.

Performance and Evaluation of Concentrating Solar Collectors for Power Generation

1965 ◽  
Vol 87 (1) ◽  
pp. 1-7 ◽  
Author(s):  
B. Y. H. Liu ◽  
R. C. Jordan
Keyword(s):  
Power Generation ◽  
Focal Plane ◽  
Flux Distribution ◽  
Solar Concentrator ◽  
Solar Collectors ◽  
Optimum Size ◽  
Target Error ◽  
Performance And Evaluation ◽  
Normal Law ◽  
General Method

The geometrical accuracy of a real solar concentrator is defined quantitatively in terms of two equivalent parameters: the standard target error and the angular error; and the relationships between these parameters and the flux distribution on the focal plane are developed. A general method for determining the optimum size and efficiency of an absorber for any given concentrator is described. Specific numerical results are obtained; however, only for the case where the function describing the flux distribution on the focal plane is given by Gauss’ normal law of error. Criteria for determining the applicability of the results are proposed. Finally, experimental techniques (both optical and thermal) of evaluating concentrators are briefly described.

Multi-segmented piezoelectric mirrors as active/adaptive optics components

1998 ◽  
Vol 5 (3) ◽  
pp. 797-800 ◽  
Author(s):  
Riccardo Signorato ◽  
Olivier Hignette ◽  
José Goulon
Keyword(s):  
Surface Quality ◽  
Adaptive Optics ◽  
Full Range ◽  
Low Frequency ◽  
Optical Surface ◽  
Surface Slope ◽  
Adaptive Compensation ◽  
Angular Acceptance ◽  
Shape Errors ◽  
Slope Error

The angular acceptance of piezoelectric (Pzt) bimorph mirrors is limited by the maximum length of commercially available Pzt ceramic plates. To overcome this limit and manufacture longer devices, several (2n + 1) 150 mm-long bimorph Pzt stacks were assembled side-to-side. Two prototype mirrors, 450 (n = 1) and 750 (n = 2) mm long, were designed, assembled, polished and optically characterized. They are fully UHV compatible and are now installed in the monochromatic section of the ESRF beamlines ID26 and ID32. Both mirrors cover the full range of required bending radii (1 km concave–3.5 km convex). Junctions between segments do not spoil the optical surface quality. The surface slope error r.m.s. can be kept well below 1 arcsec over the full bending range. Adaptive compensation for low-frequency figure errors was shown to be easy and reliable. After compensation, residual shape errors are of the order of 40 nm r.m.s. over 700 mm.

scholarly journals Practical Estimation of Landslide Kinematics Using PSI Data

Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 214
Author(s):  
Chiara Crippa ◽  
Federico Agliardi
Keyword(s):  
Field Data ◽  
Rock Slope ◽  
Site Investigation ◽  
Landslide Hazard ◽  
Suitable Model ◽  
Surface Slope ◽  
Persistent Scatterer ◽  
Complex Landslide ◽  
Landslide Kinematics ◽  
Definition Of

Kinematics is a key component of a landslide hazard because landslides moving at similar rates can affect structures or collapse differently depending on their mechanisms. While a complete definition of landslide kinematics requires integrating surface and subsurface site investigation data, its practical estimate is usually based on 2D profiles of surface slope displacements. These can be now measured accurately using Persistent Scatterer InSAR (PSI), which exploits open access satellite imagery. Although 2D profiles of kinematic quantities are easy to retrieve, the efficacy of possible descriptors and extraction strategies has not been systematically compared, especially for complex landslides. Large, slow rock slope deformations, characterized by low displacement rates (<50 mm/year) and spatial and temporal heterogeneities, are an excellent testing ground to explore the best approaches to exploit PSI data from Sentinel-1 for kinematic characterization. For three case studies, we extract profiles of different kinematic quantities using different strategies and evaluate them against field data and simplified numerical modelling. We suggest that C-band PSI data allow for an effective appraisal of complex landslide kinematics, provided that the interpretation is (a) based on decomposed velocity vector descriptors, (b) extracted along critical profiles using interpolation techniques respectful of landslide heterogeneity, and (c) constrained by suitable model-based templates and field data.

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