A solar energy resources assessment in Mozambique

Just as with other Southern African Development Community (SADC) countries, Mozambique faces severe, interrelated problems of energy and environment linked, with massive consumption of fuel wood biomass. The conventional power grid provides less than 7% of the energy needs for the country’s 17 million inhabitants, and about 83% of the energy consumed in the country comes from biomass. Renewable energy resources can play an important role in the process of development of the country. From the vast renewable energy resources available in the country, solar energy represents one of those with the highest potential. Thus, the evaluation of the potential of solar energy systems in small-scale applications suitable for villages is a strategically good starting point for promotion of sustainable rural development. One of the major impediments in carrying out such studies is the fact that the exact behaviour of solar energy resources throughout the country has not been well studied. In this paper a general characterisation of the global, diffuse and direct solar radiation fields in Mozambique is presented. The study is based on experimental data measured by the National Institute of Meteorology (INAM) in the period 1970- 2000. For these analyses global, diffuse and direct solar radiation data from three stations along the coast line and three stations in the interior of the country have been used. The six stations were representative of the three main regions of the country, namely south, centre and north. Furthermore, sunshine hours data of one selected station was analysed

Fabrication and characterization of CuInSe₂/CdS/ZnO thin film solar cells

M.Sc.I-III-VI2 compound semiconductors are important photovoltaic (PV) materials with optical and electrical properties that can be tuned for optimum device performance. Recent studies indicated that the efficiencies (1) > 18%) of CuInSe2/CdS/ZnO thin film devices are in good agreement with that of standard silicon cells. In this study, CuInSe 2 absorber films with excellent material properties were produced by relatively simple and reproducible two-stage growth techniques. In these approaches, metallic precursors (Cu/InSe, InSe/Cu, Cu/InSe/Cu and InSe/Cu/InSe) were deposited by thermal evaporation from specially designed graphite heaters at temperatures around 200°C. In the second stage of the process, the alloys were exposed to elemental Se vapour or H2Se/Ar gas. A systematic study was conducted in order to determine optimum growth parameters for the different deposition processes. Optimum material properties (homogeneous and dense films with a high degree of compositional uniformity) were obtained when InSe/Cu/InSe precursors were selenized in elemental Se vapour or H2Se/Ar gas. Comparative studies also indicated that the reaction kinetics is enhanced when H2Se/Ar is used as chalcogen source. Fully selenized films were obtained at temperatures as low as 450°C in a H2Se/Ar atmosphere, compared to temperatures of 600°C in the case of Se vapour. The optical and electrical properties of the absorber layers were accurately controlled by small variations in the bulk composition of the films. A standard CdS/ZnO window layer technology was also developed in our laboratories and preliminary solar cell devices were fabricated and evaluated

Optimization of quaternary and pentenary chalcopyrite for applications in thin film solar cells

Ph.D.One of the solutions to the high cost of solar modules is the development of thin film solar cell technologies, which enable material saving, few processing steps, good stability in outdoor testing, high conversion efficiency and flexibility for large area coatings. Polycrystalline CuInSe2 (CIS) thin films and related quaternary and pentenary compounds such as Cu(In,Ga)Se2 (CIGS) and Cu(In,Ga)(Se,S)2 (CIGSS) are the most promising thin film candidates to fulfil the requirements of economically viable solar modules. Presently CIS, CIGS and CIGSS thin film solar cells are prepared mostly by two – stage deposition processes, where Cu-In-Ga alloys are deposited, followed by selenization and/or sulfurization using H2Se/Ar and/or H2S/Ar gases, Se and/or S vapours. Key problems related to this approach are (1) the widely reported compositional change and loss of material during the annealing and selenization stages, and (2) the formation of a graded film structure with most of the Ga residing at the back of the film, due to the difference in the reaction rates between the binary selenides. The present study aims to develop CIGS quaternary and CIGSS pentenary thin film absorbers which are substantially homogeneous and single phase. In order to achieve this aim different deposition processes were developed. This included thermal evaporation of pulverized compound materials from a single crucible with and without subsequent reaction of the precursors in Se vapour or H2Se/Ar atmosphere. Alternatively, controlled partial selenization/sulfurization of the Cu-In-Ga magnetron sputtered precursor films under controlled conditions of reaction time, temperature and gas phase concentration were applied to produce CIGSS films. The latter approach allowed homogeneous incorporation of Ga and S species into CIS compound material, and with that a corresponding increase of band gap of the material in the active region of the solar cell. CIGS quaternary and CIGSS pentenary based solar cells were completed by depositing a CdS buffer layer of around 50 nm thickness, high resistivity ZnO and low resistivity Al – doped ZnO with thicknesses of about 50 nm and 0.5 μm respectively. I-V measurements on fabricated solar cells, under standard A.M. 1.5 conditions, demonstrated good solar cell device quality with efficiencies of about 10 % and 15% respectively

Organizing debate, debating organization

International audienceControversy analysis is a broad topic where the opinions of different stakeholders are analyzed to identify the various arguments that are stated and classify the positions taken on the subject. Gathering this data can be very time-consuming to do manually and usually is error-prone and not exhaustive. Automated text classification can enhance this process and make it possible to analyze controversial topics by analyzing lists of relevant documents in a short timeframe. In this paper, we propose a 2-step approach to optimize the extraction and classification of arguments in textual data from controversial topics. First, we extract the most relevant paragraphs for the controversy with a retrieval model and then we use an argument mining model to find and classify the relevant arguments. With this method, we are able to successfully characterize long documents and understand the various opinions that are recorded

Variation of chickpea nodulation in a mediterranean agroecosystem: Relationship with soil characteristics and thresholds for significant contribution to plant growth

International audienceThis study was designed to investigate the influence of some environmental constraints on chickpea (Cicer arietinum L.) growth and nodulation in a reference agroecosystem. This multi-local field experiment, realized in the agroecosystem of Chlef in northern Algeria, involved 24 sites where the local well-adapted genotype Ain temouchent is grown. Determination of soil properties allowed the identification of three clusters of sites. Plant biomass (SDW) varied significantly among sites from 6.7 to 39.4 g SDW plant-1 and was highly correlated with nodule biomass (NDW). The slope of the regression function between NDW and SDW, defined as the efficiency in use of the rhizobial symbiosis (EURS) inside clusters ranged from 67 to 200 g SDW g-1 NDW. Analysis of the EURS highlighted the existence of a low nodulation threshold of 0.1 g NDW plant-1 below which the contribution of nodulation to the host plant growth was not significant and a high threshold above which the nodule biomass increase was not linked with an increase in shoot biomass. Thus, the significant regression of shoot growth as a function of nodulation ranged from 0.10 to 0.35 g NDW plant-1 (R2 = 0.54, P < 0.001). Moreover, nodule biomass was positively correlated with soil Olsen-P, more particularly in cluster A (R2 = 0.50, P < 0.05) and B (R2 = 0.61, P < 0.01). This approach proved to be a rapid and efficient way to identify the major factors affecting nodulation in order to develop strategies to optimize nodule contribution to chickpea growth and yield

A solar energy resources assessment in Mozambique

Just as with other Southern African Development Community (SADC) countries, Mozambique faces severe, interrelated problems of energy and environment linked, with massive consumption of fuel wood biomass. The conventional power grid provides less than 7% of the energy needs for the country's 17 million inhabitants, and about 83% of the energy consumed in the country comes from biomass. Renewable energy resources can play an important role in the process of development of the country. From the vast renewable energy resources available in the country, solar energy represents one of those with the highest potential. Thus, the evaluation of the potential of solar energy systems in small-scale applications suitable for villages is a strategically good starting point for promotion of sustainable rural development. One of the major impediments In carrying out such studies is the fact that the exact behaviour of solar energy resources throughout the country has not been well studied. In this paper a general characterisation of the global, diffuse and direct solar radiation fields in Mozambique Is presented. The study Is based on experimental data measured by the National Institute of Meteorology (INAM) In the period 1970-2000. For these analyses global, diffuse and direct solar radiation data from three stations along the coast line and three stations in the interior of the country have been used. The six stations were representative of the three main regions of the country, namely south, centre and north. Furthermore, sunshine hours data of one selected station was analysed

General characterisation of the solar radiation components in Mozambique

Just as with the other Southern African Development Community (SADC) countries, Mozambique faces severe and interrelated problems of energy and environment linked with the massive consumption of fuel wood biomass. The conventional power grid provides less than 7% of the energy needs for the country's 17 million inhabitants, and about 83% of the energy consumed in the country comes from biomass. Areas around the major urban centres and along the main development corridors are the most affected by energy shortages. This hinders the country's economic and social development as it is generally acknowledged that no development can be sustainable without linking it to energy planning and environmental management. Renewable energy resources can play an important role in the process of development of the country. From the vast renewable energy resources available in the country, solar energy represents one of those with the highest potential. Thus the evaluation of the potential of solar energy systems in small-scale applications suitable for villages is a strategically good starting point for promotion of a sustainable rural development. One of the major impediments in carrying out such studies is the fact that the exact behaviour of solar energy resources throughout the country has not been well studied yet. In this paper a general characterisation of the global, diffuse and direct solar radiation fields in Mozambique is presented. The study is based on experimental data measured by the National Institute of Meteorology (INAM) in the period 1970-2000. Data from 11 stations recording global solar radiation, from 6 stations measuring diffuse solar radiation, as well as data from 80 sunshine hours stations have been used for this work. For this purpose the country has been divided into four main climate zones. The northern and coastal regions, representing 60% of the total surface of the country, have a tropical rain savanna climate. The inland parts of the central and southern edimentary terrains, with a share of 28%, have a dry savanna climate. A small area around the border crossing of the Limpopo River, representing 2% of the country's surface, has a dry desert climate, whereas the upland areas, with a share of 10%, have a humid temperate climate. Results of the present work reveal that the country has substantial solar energy resources for a variety of solar energy technologies. Areas with the dry savanna and dry desert climates, representing in total around 30% of the country's surface are particularly appropriate for dense placement of solar energy technologies

Radioprotection des professionnels de santé en France : Exposition, connaissances et habitudes – étude EXPERTS: Epidémiologie des rayonnements ionisants et Radioprotection des professionnels de santé en France

International audienceIntroductionLes professionnels de santé exposés aux rayonnements ionisants (RI) représentent plus de la moitié de l’ensemble des travailleurs exposés aux RI artificiels en France. L’utilisation des RI en médecine s’est développé rapidement ces 10 dernières années, en raison de l’introduction de nouvelles pratiques diagnostiques et thérapeutiques. En parallèle, la radioprotection des travailleurs a progressé (lois, dispositifs et outils) dans le but de réduire leur exposition aux RI. L’étude EXPERTS (EXposition des Professionnels de santE aux RayonnemenTs ioniSants) a plusieurs objectifs, notamment d’étudier les connaissances et habitudes de ces professionnels vis-à-vis de la radioprotection – ce que propose de faire ce présent travail. Matériel et MéthodesL’étude EXPERTS a inclus tous les professionnels de santé ayant au minimum un enregistrement dosimétrique dans le Système d'Information de la Surveillance de l'Exposition aux Rayonnements Ionisants (SISERI) pour chaque année 2009, 2014 et 2019, dans l’un des neuf établissements participant à l’étude. Les professionnels ayant changé d’emploi entre 2009 et 2019 ont été exclus. Les caractéristiques socio-professionnelles ont été recueillies via SISERI et CHIMED© (logiciel dédié aux hôpitaux). Tous les professionnels ont été invités à compléter un questionnaire portant sur divers aspects de la radioprotection.Résultats293/1268 professionnels contactés ont répondu au questionnaire (taux de participation : 23%). Des différences dans les taux de réponse ont été notées seulement selon le métier et le service. Les répondants étaient âgés en moyenne de 39,2 (±8,1) ans en 2009, avec une majorité de femmes (59%), et 85% étaient des manipulateurs d'électroradiologie médicale, infirmiers, ou médecins. Parmi les répondants, 12% déclarent porter leur dosimètre rarement ou jamais, et 15% déclarent ne pas utiliser de moyens de protections : en cause, manque de temps ou moyens de protection/dosimètres jugés inadaptés, sans intérêt, ou en nombre insuffisant. 71% des agents se considèrent exposés aux RI, 82% se disent suffisamment informés des risques liés au RI, 86% jugent leur exposition à risque acceptable/négligeable, tandis que 26% souhaiteraient recevoir prochainement une formation en radioprotection. Les questions de culture sur les RI révèlent seulement 40% de bonnes réponses.ConclusionsCe résumé présente les résultats préliminaires des réponses au questionnaire diffusé dans l’étude EXPERTS. Ceux-ci confirment un port non-systématique du dosimètre chez les professionnels de santé, et une faible proportion de travailleurs n’utilisant pas de moyens de protections. Le caractère inadapté des tabliers, lunettes plombées, et dosimètres étant mis en cause. Quelques lacunes au niveau des connaissances dans le domaine des RI et des risques ont été montrées. Ces résultats encouragent de nouvelles formations en radioprotection auprès des travailleurs du secteur santé, et l’utilisation de matériels de protection plus ergonomique. A noter la non-réponse d’une partie importante de la population d’étude - les résultats de cette étude sont ainsi à interpréter avec prudence

Exposition professionnelle aux rayonnements ionisants chez le personnel médical : tendances au cours de la période 2009-2019 dans une étude multicentrique

International audienceObjectives Health workers exposed to ionizing radiation account for + 50% of workers exposed to man-made radiation in France. Over the last decade, the use of radiation in medicine has increased due to the introduction of new practices. The EXposition des Professionnels de santE aux RayonnemenTs ioniSants study aims to evaluate and characterize the trends in radiation exposure of health workers in France between 2009 and 2019. Methods This retrospective study includes all health workers with at least one dosimetric record in the system for occupational dosimetry registration (Système d'information de la surveillance de l'exposition aux rayonnements ionisants) database for each of the years 2009, 2014, and 2019, in the hospitals included in the study. Individual external doses and socio-professional data were collected. Statistical analyses include descriptions, graphs, and logistic regressions. Results A total of 1457 workers were included (mean age: 39.8 years, 59% women). The average exposure significantly decreased between 2009 and 2019 (−0.008 mSv/year, p < 0.05). There were large discrepancies in trends according to professions, departments, hospitals, and gender. Over the 10-year study period, radiologic technologists and physicians were the most exposed (0.15 mSv (95%CI 0.14-0.16) and 0.13 mSv (0.06-0.21), respectively), but their exposure tended to decrease. Workers in nuclear medicine departments had the highest radiation exposure (0.36 mSv (0.33-0.39)), which remained stable over time. Thirty-eight percent of recorded doses were nonzero in 2009, decreasing to 20% in 2019. Conclusions This study allowed to identify physicians and radiologic technologists in nuclear medicine departments as the most exposed medical workers in France, and to show an overall decrease trend in radiation exposure. This should be instructive for radiation monitoring and safety of exposed medical workers. Key Points • Radiation exposure of healthcare workers in most medical departments has steadily decreased between 2009 and 2019 in several French hospitals. • The number of zero doses consistently increased during the study period. • Workers in nuclear medicine departments are the most exposed, especially radiologic technologists and physicians

Radioprotection des professionnels de santé en France : Exposition, connaissances et habitudes – étude EXPERTS: Epidémiologie des rayonnements ionisants et Radioprotection des professionnels de santé en France

International audienceIntroductionLes professionnels de santé exposés aux rayonnements ionisants (RI) représentent plus de la moitié de l’ensemble des travailleurs exposés aux RI artificiels en France. L’utilisation des RI en médecine s’est développé rapidement ces 10 dernières années, en raison de l’introduction de nouvelles pratiques diagnostiques et thérapeutiques. En parallèle, la radioprotection des travailleurs a progressé (lois, dispositifs et outils) dans le but de réduire leur exposition aux RI. L’étude EXPERTS (EXposition des Professionnels de santE aux RayonnemenTs ioniSants) a plusieurs objectifs, notamment d’étudier les connaissances et habitudes de ces professionnels vis-à-vis de la radioprotection – ce que propose de faire ce présent travail. Matériel et MéthodesL’étude EXPERTS a inclus tous les professionnels de santé ayant au minimum un enregistrement dosimétrique dans le Système d'Information de la Surveillance de l'Exposition aux Rayonnements Ionisants (SISERI) pour chaque année 2009, 2014 et 2019, dans l’un des neuf établissements participant à l’étude. Les professionnels ayant changé d’emploi entre 2009 et 2019 ont été exclus. Les caractéristiques socio-professionnelles ont été recueillies via SISERI et CHIMED© (logiciel dédié aux hôpitaux). Tous les professionnels ont été invités à compléter un questionnaire portant sur divers aspects de la radioprotection.Résultats293/1268 professionnels contactés ont répondu au questionnaire (taux de participation : 23%). Des différences dans les taux de réponse ont été notées seulement selon le métier et le service. Les répondants étaient âgés en moyenne de 39,2 (±8,1) ans en 2009, avec une majorité de femmes (59%), et 85% étaient des manipulateurs d'électroradiologie médicale, infirmiers, ou médecins. Parmi les répondants, 12% déclarent porter leur dosimètre rarement ou jamais, et 15% déclarent ne pas utiliser de moyens de protections : en cause, manque de temps ou moyens de protection/dosimètres jugés inadaptés, sans intérêt, ou en nombre insuffisant. 71% des agents se considèrent exposés aux RI, 82% se disent suffisamment informés des risques liés au RI, 86% jugent leur exposition à risque acceptable/négligeable, tandis que 26% souhaiteraient recevoir prochainement une formation en radioprotection. Les questions de culture sur les RI révèlent seulement 40% de bonnes réponses.ConclusionsCe résumé présente les résultats préliminaires des réponses au questionnaire diffusé dans l’étude EXPERTS. Ceux-ci confirment un port non-systématique du dosimètre chez les professionnels de santé, et une faible proportion de travailleurs n’utilisant pas de moyens de protections. Le caractère inadapté des tabliers, lunettes plombées, et dosimètres étant mis en cause. Quelques lacunes au niveau des connaissances dans le domaine des RI et des risques ont été montrées. Ces résultats encouragent de nouvelles formations en radioprotection auprès des travailleurs du secteur santé, et l’utilisation de matériels de protection plus ergonomique. A noter la non-réponse d’une partie importante de la population d’étude - les résultats de cette étude sont ainsi à interpréter avec prudence