In this study, for determining the best-input scenarios of the used parameters in predicting the Daily Global Solar Radiation (DGSR), a new approach based on Artificial Neural Networks (ANNs) was ...presented. The proposed approach is based on comparisons between all possible input combinations for determining the best scenarios that can give perfect correlations and approximations with DGSR. Recorded data from 35 stations belonging to different climatic zones (27 in Morocco and 8 in neighboring countries) were reported for training and testing the obtained results. The used input parameters include geographical coordinates, sun declination, day length, day number, clearness index (KI), Top Of Atmosphere (TOA), average ambient temperature (Ta), maximum temperature (Tmax), minimum temperature (Tmin), difference temperature (ΔT), temperature ratio (TR), relative humidity (Rh) and wind speed (Ws). The results revealed 128 best-input scenarios, where the first relevant input combination was found for KI, Ta, ΔT, TR and TOA. This result indicated that the best-input scenario for predicting DGSR is based only on three climatological parameters: KI, function of Ta f(Ta) and TOA. In addition, based on these found best-input scenarios and on the least square regression (LSR) technique, 128 new linear relationships between DGSR and the found best-input combinations were developed. The statistical analysis expressed through statistical criteria indicated perfect correlations and approximations between the predicted and measured values of DGSR.
•A new approach using ANNs for solar radiation prediction was presented.•128 best-input scenarios and new linear relationships for DGSR prediction were found.•Several statistical indexes were used to assess performances of the developed models.
This paper presents a new procedure to optimize the geometric parameters of a n-type coaxial HPGe detector. It is based on a statistical technique called “Design of Experiments” (DoE). This technique ...aims to identify the most influential parameters and to determine the optimal configuration. In this work, The effects of each parameter on the detector responses have been investigated by a fractional factorial design. Only the most influential factors contributing to the detector response have been selected. Precise modeling of these factors was then performed using a full factorial design. Based on the results obtained from this design, the full energy peak efficiencies according to the geometric parameters were modeled by a multiple-linear regression. These models have been statistically validated by analysis of variance (ANOVA). The optimal combination of the geometric parameters has been identified using the desirability function approach, which is a useful tool to optimize multi-response problems. A verification test was performed to validate the results obtained. It was observed that the relative deviation found between experimental and simulated values was less than 5%.
•Optimization of geometrical dimensions of an HPGe detector.•Application of Monte Carlo simulation and “Design of Experiments” technique.•Investigating influence of each detector parameter on the FEPE.•Achieving good agreement between the measured and the simulated results.
•Prediction of the Daily Global Solar Radiation on inclined surfaces to the south.•Multi-inclinations ranging from 0° to 90° in steps of 10°.•Five used solar radiation models and two conversion tilt ...factors.•Statistical indicators: MBE, RMSE, NRMSE, MAPE, TS, R2, Regression Coefficient.
Over the years, some authors have used different models to estimate the solar radiation intensity over inclined surfaces, but none of them has tested and evaluated the accuracy of these models for various inclinations. In this study, by using the acquired data from Meteonorm, five best models studied previously by the authors have been used in order to predict the daily global solar radiation intensity DGSRI received on an inclined surface to the south and to evaluate the day by day performance of these models using a statistical analysis performed by several statistical indicators. The analysis of results revealed that the selected models haven’t the same accuracy, and it is concluded that there are models that can be preferred for the prediction of the DGSRI received on a tilted surface with different angle of inclination at the considered site, Tetuan city in northern Morocco. Empirical correlations between solar radiation intensity fallen on south-facing plane surfaces with various inclination and that receive on horizontal surfaces have been developed. As mean of results of the statistical indicator errors and excluding 20°, 60° and 70° inclinations and the coefficient of determination R2 values, El Mghouchi model is performing comparatively better than the others for all inclinations ranging from 0° (horizontal plane) to 90° (vertical plane) in steps of 10°.
This study presents a comprehensive statistical analysis of the cosmogenic radioisotope 7Be measured in surface air in ten stations over Spain for a 9 years period (from January 2006 to December ...2014).
Besides the analysis of 7Be seasonal and inter-annual variability, 7Be frequency distributions and its correlations with meteorological variables observed in the 10 sampling sites were investigated.
The second part of this paper focuses on a feasibility study for the application of the Artificial Neural Networks (ANNs) to predict monthly 7Be activity concentrations using meteorological variables, PM10 concentrations and the sunspot number as input parameters. Notwithstanding the low correlations found between 7Be and input parameter, the performance of the ANNs, as evaluated by the relevant statistical parameters, demonstrates their capability to correctly predict 7Be monthly activities in the 10 Spanish sampling sites.
•9 years of monthly measurements of 7Be in 10 sampling sites were investigated.•Temporal, spatial, and frequency distribution of the 7Be activity were treated.•The ANN method was proposed to forecast 7Be activity.•The ANN model provides robust forecasts of 7Be air concentrations for all stations.
The main objective of this study is to analyse neutronic safety parameters of the Moroccan TRIGA Mark-II research reactor using the WIMSD-5B and CITATION computer codes. New 172-group libraries of ...multi-group constants for the lattice code WIMSD-5B have been generated for all isotopes presented in the TRIGA reactor core by processing nuclear data from ENDFB-VII.1, JENDL-4.0 and JEFF-3.1.1 using NJOY99. The lattice code WIMSD-5B was employed to generate multi-group cross sections in the suitable format that will be used by the 3-dimensional diffusion code CITATION. This later was used to calculate various neutronic safety parameters of the TRIGA Mark-II research reactor, such as reactivity excess and neutron fluxes profiles. The results of these calculations are compared to the results of Monte Carlo calculation based on MCNP code. A good agreement is achieved and the current computation scheme will be adopted for our further coupling neutronic/thermal-hydraulic study of the Moroccan TRIGA reactor.
•Simulation of the Moroccan TRIGA Mark-II research reactor.•WIMSD-5B code and CITATION have been utilized to model the core.•Calculations are performed by use of ENDFB-VII.1, JENDL-4.0 and JEFF-3.1.1 libraries.•Calculation results are compared to experiment and MCNP simulation results.
This research is focused on studying the preferred source regions and the pathways of the air masses with high particulate concentrations impacting on the activity concentrations of 7Be and 210Pb ...aerosols in Granada atmosphere. For this purpose, three different source-receptor methods have been used: Cluster Analysis, Potential Source Contribution Function (PSCF), and Concentration Weighted Trajectory (CWT). Air filter samples were weekly collected and analysed in Granada university (Spain 37.177N, 3.598 W, 687m a.s.l.) during 12 years (2006–2017) for the activity concentration of 7Be, and during 5 years (2010–2014) for the one of 210Pb. The time series of the collected data indicate that the concentration of both radiotracers present a cyclical and seasonal pattern, in association with their origins and atmospheric conditions. Clustering analysis showed that the air masses arriving to Granada can be classified as: (1) tropical continental air masses coming from the Mediterranean Sea, (2) tropical and warm polar maritime air masses produced over the Atlantic Ocean, and (3) continental air masses originated over Europe and Northern Africa. The PSCF and CWT methods confirmed that the main source areas of 7Be are located in the Atlantic coast of southern Morocco, and Northern Africa. On the other hand, southern France and the Algerian desert were found to be the main region sources of 210Pb. In addition, the Mediterranean Basin has been postulated as a strong source region for 7Be and 210Pb. Furthermore, the PSCF and CWT models show that the regions with larger 7Be/210Pb ratios are located in the Atlantic Ocean, due to frequent stratospheric intrusions specially during the winter months.
•A seasonal pattern of 7Be and 210Pb was identified in Granada, Spain.•Back trajectory analysis was used to identify the origin and pathway of air masses.•Potential sources regions of 7Be and 210Pb activity were investigated.•Granada is affected by Mediterranean Sea, Atlantic Ocean, and Sahara.•Mediterranean basin is the main source common of 210Pb and 7Be.
The main objective of this work is to perform a neutronic study of the 2 MW TRIGA MARK-II research reactor of the National Centre of Sciences, Energy and Nuclear Techniques (CNESTEN), Rabat, Morocco ...and then validate the results by comparing the experimental values and those published for an ordinary 2 MW TRIGA MARK II research reactor. The core diffusion code DONJON5 and the lattice code DRAGON5 were coupled to perform a full model of the TRIGA core and their consistency and accuracy were established by benchmarking the TRIGA experiments. In this study, the nuclear data libraries ENDF/B-VII.1 and JEFF3.1 based on 172 energy groups were used. The group constants of all the reactor components were generated using DRAGON5 code and the collision probability method. These group constants were used then in the DONJON5 core code to calculate the multiplication factor, core excess reactivity, total and integral control rods worth as well as power peaking factors. Good agreement found between the calculated and measured results.
•Neutronic calculations of the TRIGA MARK II research reactor.•Validation of the deterministic transport code DRAGON5 and diffusion code DONJON5.•Calculation and analysis of control rod worth, excess reactivity as well as power peaking factors by deterministic codes.•The good consistency of the results ensures that a thermal-hydraulic analysis will be performed for TRIGA reacteor.•To rely on DRAGON5 and DONJON5 codes for TRIGA Mark-II calculations.
This paper presents a case study of applying Genetic Algorithm (GA) coupled with Monte Carlo N-Particle Transport (MCNP) and PARET codes for a thermal-hydraulic and safety analysis to optimize the ...fuel reload for the TRIGA Mark II Moroccan research reactor. Based on the radial distribution of the 238U burnup ratio inside the reactor core, the five most burned fuel elements were replaced by others fresh fuel elements (12 % wt of uranium) using the Multi-Objective Genetic Algorithms (MOGA) method. Three aspects for the fuel reload optimization were considered in this study including 1) maximization of the effective multiplication factor (Keff), 2) minimization of maximum Centre Fuel Temperature (CFT) and 3) maximization of the Departure from Nuclear Boiling Ratio (DNBR).
The GA programming process developed in this work was adapted to handle the constraints concerning the safety limits for the successive core configurations (CCs) automatically generated by the code. MOGA method works with an elitist selection based on the Binary Tournament Selection (BTS) method, a modified two-point crossover and a simple mutation operator. The results obtained indicate that the MOGA can successfully find an optimal CC with a Keff of 1.03498, a maximum CFT of 554 °C and a DNBR of 2.94 when five fresh fuel elements are inserted. The variation of neutron fluxes with respect to radial distance for the best CC and the fresh core was illustrated.
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•Optimum core configurations were generated for the Moroccan TRIGA Mark II research reactor.•Calculations were performed using a global reactor calculation, formed by MCNP and PARET codes.•Genetic Algorithms were used to optimize three parameters at once.•Keff and the safety constraints on the CFT and DNBR were considered for optimization.•The optimal core configuration was determined and compared with the fresh core map.
We have carried out a study to figure out the influence of crystal inactive-layer thickness on gamma spectra measured by an HPGe detector. The thickness of this dead layer (DL) is not known (no ...information about it was delivered by the manufacturer) due to the existence of a transition zone where photons are increasingly absorbed. To perform this analyses a virtual model of a Canberra HPGe detector was produced with the aid of MCNPX 2.7 code.
The main objective of this work is to produce an optimal modeling for our GPGe detector. To this end, the study included the analysis of the total inactive germanium layer thickness and the active volume that are needed in order to obtain the smallest discrepancy between calculated and experimental efficiencies. Calculations and measurements were performed for all of the radionuclides included in a standard calibration gamma cocktail solution. Different geometry sources were used: a Marinelli and two other new sources represented as S(1) and S(2). The former was used for the determination of the active volume, whereas the two latter were used for the determination of the face and lateral DL, respectively. The model was validated by comparing calculated and experimental full energy peak efficiencies in the 50–1900keV energy range. the results show that the insertion of the DL parameter in the modeling is absolutely essential to reproduce the experimental results, and that the thickness of this DL varies from one position to the other on the detector surface.
•Modeling of a HpGe detector was realized with the manufacture’s data.•Inclusion of dead layer has improved the simulation of the experimental efficiencies.•Dead layer and volume of crystal are the parameters most influent on calculations.•Lower energies are more sensitive to the change in the dead layer thickness.•Variation of the active volume has a clear effect on the higher energies.
The current research has been developed in the southern of the Iberian Peninsula in order to better understand the atmospheric processes and also the influence of the air masses origin and pathways ...in the transport of 210Pb-aerosols in the atmosphere. Simultaneous measurements of the radionuclides 7Be and 210Pb on airborne have been routinely carried out at Granada (Spain 37.177N, 3.598 W, 687 m a.s.l.) from 2010 to 2014. The long term monitoring evolution on 210Pb is discussed in this study and also the useful ratio 7Be/210Pb.
The maximum monthly activity concentration for 210Pb at ground level in Granada was detected during summer and early autumn (September), whereas minimum activity was measured in the winter. The monthly mean activity concentration for 210Pb was 617.8 ± 33.0 μBq·m−3. The results show that the annual average 210Pb concentrations in samples collected during the same period were almost constant.
The lowest activity concentration for 210Pb are associated with maritime air masses coming from Atlantic and Norwest of Spain, while the highest activity concentrations for this radiotracers were positively correlated with the arrival of mineral dust linked to continental air masses coming from Mediterranean, Africa and Local area. The concentrations values show a nice agreement with the relevant reported results.
•The influence of air masses origin over the 210Pb levels was studied.•The 7Be/210Pb ratio reflects the influence of air masses origin.•The Norwest and Atlantic air masses are associated to low values of 210Pb.•The local area and Africa dust inputs increase the radioactivity levels.•Mediterranean and African air masses favor the arrival of 210Pb and 7Be.
