scholarly journals Geometrical optimization for a photovoltaic installation equipped with flat reflectors based on plane of array estimations

2020 ◽  
Vol 11 ◽  
pp. 1 ◽  
Author(s):  
Christine Abdel Nour ◽  
Anne Migan-Dubois ◽  
Jordi Badosa ◽  
Vincent Bourdin ◽  
Claude Marchand ◽  
...  
Keyword(s):  
Power Production ◽  
Geometrical Parameters ◽  
Estimation Model ◽  
Geometrical Characteristics ◽  
Pv Module ◽  
Geometrical Optimization ◽  
Reflector System ◽  
The Mean ◽  
Experimental Validations ◽  
Geographical Characteristics

In order to design, manage and optimize the performance of a photovoltaic (PV) installation and establish a precise power production estimation, irradiance on the plane of array (POA) in relation with the geometrical characteristics of the PV modules installation occupies a high importance. This study focuses on the development of an estimation model of the POA irradiance for a photovoltaic installation equipped with flat reflectors. The model includes solar irradiance components (global, direct and diffuse), geometrical parameters and geographical characteristics of the PV installation. Experimental validations have been performed with measurements taken at the SIRTA Observatory (48.7°N, 2.2°E) in Palaiseau, France, for the period starting from June 2017 to June 2018. Results show mean absolute errors (relative to the mean) of 6% and 7% for an installation without and with planar reflector. Finally, we present several geometrical optimization strategies of the PV-reflector installation relying on two major variables: the reflector's length (LR) compared to the length of the PV module (LPV) and the tilt angle adjustment frequency (monthly, seasonally, fixed) of the system (for both PV and the reflectors). The objective of such optimization is to discuss about a reasonable configuration to achieve a maximum POA irradiance. Results show that the length of the mirrors highly affects the efficiency and performances of the PV-Reflector system and the annual gain increased from 8.5% to 28.7% when going from LR = LPV/2 to LR = 2 × LPV compared to a monthly-optimized installation without mirrors. As for the adjustment frequency, we show that a monthly-varied architecture is the most advantageous option with a 28.2 and 31.6% increasing in annual gain compared to a seasonal varied or fixed ones, respectively.

scholarly journals Nonlinear analysis of magnetospheric data Part I. Geometric characteristics of the AE index time series and comparison with nonlinear surrogate data

1999 ◽  
Vol 6 (1) ◽  
pp. 51-65 ◽  
Author(s):  
G. P. Pavlos ◽  
M. A. Athanasiu ◽  
D. Kugiumtzis ◽  
N. Hatzigeorgiu ◽  
A. G. Rigas ◽  
...  
Keyword(s):  
Time Series ◽  
State Space ◽  
Null Hypothesis ◽  
Surrogate Data ◽  
Statistical Testing ◽  
Geometrical Parameters ◽  
Geometric Characteristics ◽  
Geometrical Characteristics ◽  
Ae Index ◽  
Index Time Series

Abstract. A long AE index time series is used as a crucial magnetospheric quantity in order to study the underlying dynainics. For this purpose we utilize methods of nonlinear and chaotic analysis of time series. Two basic components of this analysis are the reconstruction of the experimental tiine series state space trajectory of the underlying process and the statistical testing of an null hypothesis. The null hypothesis against which the experimental time series are tested is that the observed AE index signal is generated by a linear stochastic signal possibly perturbed by a static nonlinear distortion. As dis ' ' ating statistics we use geometrical characteristics of the reconstructed state space (Part I, which is the work of this paper) and dynamical characteristics (Part II, which is the work a separate paper), and "nonlinear" surrogate data, generated by two different techniques which can mimic the original (AE index) signal. lie null hypothesis is tested for geometrical characteristics which are the dimension of the reconstructed trajectory and some new geometrical parameters introduced in this work for the efficient discrimination between the nonlinear stochastic surrogate data and the AE index. Finally, the estimated geometric characteristics of the magnetospheric AE index present new evidence about the nonlinear and low dimensional character of the underlying magnetospheric dynamics for the AE index.

scholarly journals Estimation of Above-Ground Mangrove Biomass Using Landsat-8 Data- Derived Vegetation Indices: A Case Study in Quang Ninh Province, Vietnam

2021 ◽  
pp. 506-525
Author(s):  
Hai-Hoa Nguyen ◽  
Huy Duc Vu ◽  
Achim Röder
Keyword(s):  
Vegetation Indices ◽  
Landsat 8 ◽  
Mangrove Forests ◽  
Estimation Model ◽  
The Status ◽  
Good Potential ◽  
The Mean ◽  
Accuracy Assessments ◽  
Quang Ninh

This study aimed to map the status of mangrove forests over the coasts of Hai Ha District and Mong Cai City in Quang Ninh Province by using 2019 Landsat-8 imagery. It then developed the AGB estimation model of mangrove forests based on the AGB estimation-derived plots inventory and vegetation indices-derived from Landsat-8 data. As results, there were five land covers identified, including mangrove forests, other vegetation, wetlands, built-up, and water, with the overall accuracy assessments of 80.0% and Kappa coefficient of 0.74. The total extent of mangrove forests was estimated at 4291.2 ha. The best AGB estimation model that was selected to estimate the AGB and AGC of mangrove forests for the whole coasts of Hai Ha District and Mong Cai City is AGB= 30.38 + 911.95*SAVI (R2=0.924, PValue <0.001). The model validation assessment has confirmed that the selected AGB model can be applied to Hai Ha and Mong Cai coasts with the mean difference between AGB observed and AGB predicted at 16.0 %. This satisfactory AGB model also suggests a good potential for AGB and AGC mapping, which offer the carbon trading market in the study site. As the AGB model selected, the total AGB and AGC of mangrove forests were estimated at about 14,600,000 tons and 6,868,076 tons with a range of from 94.0 - 432.0 tons ha-1, from 44.2 - 203.02 tons ha-1, respectively. It also suggests that the newly-developed AGB model of mangrove forests can be used to estimate AGC stocks and carbon sequestration of mangrove forests for C-PFES in over the coasts of Hai Ha District and Mong Cai City, which is a very importantly financial source for mangrove forest managers, in particular for local mangrove protectors.

scholarly journals Outdoor Performance Test of Bifacial n-Type Silicon Photovoltaic Modules

2019 ◽  
Vol 11 (22) ◽  
pp. 6234 ◽  
Author(s):  
Hyeonwook Park ◽  
Sungho Chang ◽  
Sanghwan Park ◽  
Woo Kyoung Kim
Keyword(s):  
Tilt Angle ◽  
Performance Test ◽  
Power Production ◽  
Energy Yield ◽  
Concrete Floor ◽  
Photovoltaic Modules ◽  
Pv Module ◽  
Pv Modules ◽  
Solar Tracker ◽  
One Year

The outdoor performance of n-type bifacial Si photovoltaic (PV) modules and string systems was evaluated for two different albedo (ground reflection) conditions, i.e., 21% and 79%. Both monofacial and bifacial silicon PV modules were prepared using n-type bifacial Si passivated emitter rear totally diffused cells with multi-wire busbar incorporated with a white and transparent back-sheet, respectively. In the first set of tests, the power production of the bifacial PV string system was compared with the monofacial PV string system installed on a grey concrete floor with an albedo of ~21% for approximately one year (June 2016–May 2017). In the second test, the gain of the bifacial PV string system installed on the white membrane floor with an albedo of ~79% was evaluated for approximately ten months (November 2016–August 2017). During the second test, the power production by an equivalent monofacial module installed on a horizontal solar tracker was also monitored. The gain was estimated by comparing the energy yield of the bifacial PV module with that of the monofacial module. For the 1.5 kW PV string systems with a 30° tilt angle to the south and 21% ground albedo, the year-wide average bifacial gain was determined to be 10.5%. An increase of the ground albedo to 79% improved the bifacial gain to 33.3%. During the same period, the horizontal single-axis tracker yielded an energy gain of 15.8%.

scholarly journals The DN − σ and Fundamental Plane Relations as Distance Indicators of Early Type Galaxies in the Virgo and Fornax Clusters

1996 ◽  
Vol 171 ◽  
pp. 366-366
Author(s):  
M. D'Onofrio ◽  
S. Zaggia ◽  
M. Capaccioli ◽  
G. Longo ◽  
N. Caon
Keyword(s):  
Rotation Velocity ◽  
Geometrical Parameters ◽  
Early Type ◽  
Homogeneous Sample ◽  
Fundamental Plane ◽  
Total Luminosity ◽  
The Mean ◽  
Distance Indicators ◽  
Light Profiles

We investigate the properties of early-type galaxies as distance indicators by applying the Dn – σ, Fundamental Plane (FP), and log(m) – log re relations to a complete and fairly homogeneous sample of galaxies members of the Virgo and Fornax clusters. The relative mean distance of the two clusters can be derived with an accuracy up to ∼ 3% provided that the internal kinematics of the galaxies is taken into account and a correct statistical approach is used.The residuals of the Dn – σ and FP relationships do not correlate with many structural and geometrical parameters of the galaxies: the mean effective surface brightness, the total luminosity, the average ellipticity and the Fourier coefficient a4 of the isophotes, and, the exponent m of the r1/m law which parametrizes the shape of the light profiles. On the other hand, the kinematics of the galaxies affect both relations producing residuals that correlate with the maximum rotation velocity Vmax and the (V/σ) ratio.Once confirmed by future more accurate observations, this effect would introduce a sistematic bias in the distance determination of the clusters; a problem difficult to manage if the internal kinematics of the cluster members is unknown.

Transient Performance of a Finned PCM Heat Sink

2005 ◽  
Author(s):  
V. Shatikian ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Phase Change ◽  
Melting Temperature ◽  
Phase Change Material ◽  
Heat Sink ◽  
Geometrical Parameters ◽  
Transient Performance ◽  
The Mean ◽  
Liquid States ◽  
Fin Thickness ◽  
Change Material

The present study explores numerically the transient performance of a heat sink based on a phase change material (PCM), during the process of melting. Heat is transferred to the sink through its horizontal base, to which vertical fins made of aluminum are attached. The phase change material is stored between the fins. Its properties, including the melting temperature, latent and sensible specific heat, thermal conductivity and density in solid and liquid states, are based on a commercially available paraffin wax. A parametric investigation is performed for melting in a relatively small system, 10mm high, where the fin thickness is 1.2mm, and the distance between the fins varies from 2mm to 8mm. The temperature of the base varies from 12°C to 24°C above the mean melting temperature of the PCM. Transient numerical simulations are performed, yielding temperature evolution in the fins and the PCM. The computational results show how the transient phase-change process, expressed in terms of the volume melt fraction of the PCM, depends on the thermal and geometrical parameters of the system, which relate to the temperature difference between the base and the mean melting temperature, and to the thickness of the PCM layer.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.

scholarly journals Retrieving the characteristics of slab ice covering snow by remote sensing

2016 ◽  
Vol 10 (5) ◽  
pp. 2113-2128 ◽  
Author(s):  
François Andrieu ◽  
Frédéric Schmidt ◽  
Bernard Schmitt ◽  
Sylvain Douté ◽  
Olivier Brissaud
Keyword(s):  
Thick Layer ◽  
Radiative Transfer Model ◽  
Inversion Method ◽  
Transfer Model ◽  
Retrieval Method ◽  
Water Ice ◽  
Air Interface ◽  
The Mean ◽  
Experimental Validations ◽  
Grain Diameter

Abstract. We present an effort to validate a previously developed radiative transfer model, and an innovative Bayesian inversion method designed to retrieve the properties of slab-ice-covered surfaces. This retrieval method is adapted to satellite data, and is able to provide uncertainties on the results of the inversions. We focused on surfaces composed of a pure slab of water ice covering an optically thick layer of snow in this study. We sought to retrieve the roughness of the ice–air interface, the thickness of the slab layer and the mean grain diameter of the underlying snow. Numerical validations have been conducted on the method, and showed that if the thickness of the slab layer is above 5 mm and the noise on the signal is above 3 %, then it is not possible to invert the grain diameter of the snow. In contrast, the roughness and the thickness of the slab can be determined, even with high levels of noise up to 20 %. Experimental validations have been conducted on spectra collected from laboratory samples of water ice on snow using a spectro-radiogoniometer. The results are in agreement with the numerical validations, and show that a grain diameter can be correctly retrieved for low slab thicknesses, but not for bigger ones, and that the roughness and thickness are correctly inverted in every case.

Discharge Coefficient Correlations for Circular-Arc Venturi Flowmeters at Critical (Sonic) Flow

1974 ◽  
Vol 96 (2) ◽  
pp. 111-123 ◽  
Author(s):  
B. T. Arnberg ◽  
C. L. Britton ◽  
W. F. Seidl
Keyword(s):  
Discharge Coefficient ◽  
Reynolds Numbers ◽  
Critical Flow ◽  
Geometrical Parameters ◽  
Circular Arc ◽  
Property Data ◽  
Operational Variables ◽  
Optimum Approach ◽  
The Mean ◽  
Flow Functions

Data are presented which tend to verify the theoretically predicted discharge coefficients for circular-arc venturi flow meters operating in the critical flow regime (sonic) at throat Reynolds numbers above 1.5 105. Extensive analysis of the data is presented using methods that are presently in process of international standardization. The data tend to verify the theoretically predicted decrease of 0.25 percent in the discharge coefficient during transition from laminar to a turbulent boundary layer. The transition occurred at a throat Reynolds number of 2.2 106, but the transition point probably changes as a function of several influences. The mean line of the measured data fell between the theoretical values for laminar and turbulent boundary layers. The scatter in 55 data points was ±0.212 percent (95 percent confidence level) from the mean line equation for Reynolds numbers from 4.1 104 to 3.4 106, which included the effects of several variables. Data were obtained from 17 venturis with throat sizes from 0.15 to 1.37 in. with Beta ratios ranging from 0.014 to 0.25. Four different test gases and three primary flow measurement facilities were used. Additional data are presented extending down to throat Reynolds numbers of 1.3 104 and throat diameters of 0.05 in. which indicate special problems in these regions. The state of the art for measuring venturi throat diameters presented a major limitation to the correlation effort. Calibration is necessary in many cases depending on various parameters and requirements. Additional study is needed to determine the optimum geometrical parameters at low Reynolds numbers, the optimum approach configuration for Beta ratios above 0.1, the effect of surface roughness on the discharge coefficient, and the effect of various operational variables such as flow pulsation and approach velocity profile. Also, a continuous effort should be made to improve the critical flow functions for real gases as better gas property data become available, and to extend these calculations to broader ranges of pressures and temperatures, and to other gases.

Numerical Modelling of Metal Foams with Weaire-Phelan Cell

2013 ◽  
Vol 334-335 ◽  
pp. 122-126 ◽  
Author(s):  
Sid Ali Kaoua ◽  
Haddad Meriem ◽  
Dahmoun Djaffar ◽  
Azzaz Mohammed
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Metal Foam ◽  
Metallic Foam ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Geometrical Characteristics ◽  
Structural Network ◽  
Regular Network

The mechanical properties of open-cell metal foam structures are investigated using the finite element method. The foam structure is modelled by a regular network of anisotropic Weaire-Phelan cells in which the strands are modelled as 3D finite element beams. We consider four types of strand cross sections: (i) circular, (ii) square, (iii) triangular and (iv) Plateau border shape. The numerical results obtained with our proposed mathematical model are checked against the experimental results obtained on real Nickel metallic foam and an excellent agreement is found. In addition, we conducted a parametric analysis to study the effect of some geometrical characteristics on the elasticity of the metal foam. Among these geometrical parameters, the shape, the dimensions of strand cross section, the inertia, the alignment of strands and the structural network irregularities are investigated, discussed and documented.

Theoretical and Experimental Crushing Analysis of Metal Square Honeycombs Under Quasi-Static Loading

2010 ◽  
Author(s):  
M. Zarei Mahmoudabadi ◽  
M. Sadighi ◽  
A. Eyvazian
Keyword(s):  
Flow Stress ◽  
Static Loading ◽  
Experimental Tests ◽  
High Energy ◽  
Geometrical Parameters ◽  
External Work ◽  
Modified Model ◽  
Curvature Effects ◽  
The Mean ◽  
Honeycomb Material

Honeycomb cellular structures, due to their light weight and high energy absorbing, have been used extensively as energy absorbers or cushions to resist external loads. In this paper, the mean crushing stress and the wavelength of the folding mode, as two important parameters in the study of metal square honeycomb crushing under quasi-static loading have been investigated theoretically and experimentally. Firstly, by considering the true cylindrical curvature effects and the flow stress in the folding mode of the honeycomb material, the Wierzbicki’s model in the study of metal hexagonal honeycomb crushing under quasi-static loading is modified. This modification is performed by rewriting the internal energy terms and the external work in the energy method through the basic element folding by considering the true cylindrical curvature effects and the flow stress of the honeycomb material. Comparison of the results obtained by this modified model and Wierzbicki’s model with the experimental data shows better prediction by the model presented in this paper. Subsequently, this modified model has been extended to the study of metal square honeycombs crushing under quasi-static loading and the mean crushing stress and the wavelength of the folding mode of these structures have been predicted. This analytical model predicts the mean crushing stress of the metal square honeycomb as a function of both the geometrical parameters and its material, while the predicted wavelength of the folding mode is just a function of the geometrical parameters. Finally, the experimental tests have been performed to verify the preciseness of this theoretical model.

scholarly journals Modeling cache performance for embedded systems

2021 ◽  
Vol 10 (5) ◽  
pp. 2910-2920
Author(s):  
Ogechukwu Kingsley Ugwueze ◽  
Chijindu C. V. ◽  
Udeze C. C. ◽  
Ahaneku A. M. ◽  
Eneh N. J. ◽  
...  
Keyword(s):  
Embedded Systems ◽  
Performance Model ◽  
Replacement Policy ◽  
Cumulative Probability ◽  
Estimation Model ◽  
Cache Performance ◽  
The Mean ◽  
Design Options ◽  
Cache Design ◽  
Cache Configurations

This paper presents a cache performance model for embedded systems. The need for efficient cache design in embedded systems has led to the exploration of various methods of design for optimal cache configurations for embedded processor. Better users’ experiences are realized by improving performance parameters of embedded systems. This work presents a cache hit rate estimation model for embedded systems that can be used to explore optimal cache configurations using Bourneli’s binomial cumulative probability based on application of reuse distance profiles. The model presented was evaluated using three mibench benchmarks which are bitcount, basicmath and FFT for 4kb, 8kb, 16kb, 32kb and 64kb sizes of cache under 2-way, 4-ways, 8-ways and 16-ways set associative configurations, all using least recently-used (LRU) replacement policy. The results were compared with the results obtained using sim-cheetah from simplescalar simulators suite. The mean errors for bitcount, basicmath, and FFT benchmarks are 0.0263%, 2.4476%, and 1.9000% respectively. Therefore, the mean error for the three benchmarks is equal to 1.4579%. The margin of errors in the results was below 5% and within the acceptable limits showing that the model can be used to estimate hit rates of cache and to explore cache design options.

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