1,720,963 research outputs found
VALORISATION ENERGETIQUE ET ENVIRONNEMENTALE DES DECHETS PAPIERS ET CARTONS
No full textThe problem of paper and cardboard waste management presents local pollution, due to the presence of metal alloys used as binding and potentially dangerous for the environment and human health, and diffuse pollution, due to the presence of inks also potentially dangerous for the environment and human health. Not mastered, this management could be a real problem in the cities of developing countries. In a context where the quantities of paper and cardboard waste follow the population growth and that wood fuel is decreasing due to desertification anddeforestation, this work generally aims to propose an ecological alternative to the cutting firewood by recovering energy from paper and cardboard waste to contribute to the improvement of solid waste management and the fight against desertification. The quantification of the flow of paper and cardboard in the city of Maroua using a hypothetical-deductive methodology focused on a totalquantity of 81.7 tons of paper second generation rejected towards nature during all services in the city of Maroua between 2019-2020. During the same period, the recycling of paper and cardboard waste to produce briquettes could save between imports of raw materialsof papers and the gain in CO2 sequestration, more than 125,487.47 tons of CO2 in a sahelian citysuch as that of Maroua. The manufacture of fuel briquettes by a mechanical processallowed to determine their physical characteristics from which it emerges that their average density is 1.12 ± 0.40 with an average surface area/volume ratio of 3595.88 ± 19.90 mm-1. Their chemical characterizations made it possible to determine the rate dry average humidity of 4.00 ± 0.02%, and an average fixed carbon content of the order of 33.24 ± 1.31%. The average calorific value measured for pre-treated and optimized fuels is 41.18 ± 6.34 MJ/Kg while the average calorific value measured for fuels pretreated but not optimized is 12.65MJ / Kg. Briquettes made from paper and cardboard (90-98%) and plastic (2-10%) emit CO (1300-2110ppm), CO2 (0-1.99%) in the presence oxygen (18.4-25%) below the standard: therefore they are non-polluting forthe environment. With 81.7 tons of paper and cardboard waste produced per year, it could beproduces 102.14 tons of fuel briquettes, preserving around 153.2 tons of woodCooking. The economic benefit is guaranteed when the fuel briquettes based on deinked cardboard paper are sold at 60 FCFA / kg with a daily profit of 11,484 FCFA / Day.Le problème de gestion de déchets papier-cartons présente une pollution locale, due à la présence des alliages métalliques ayant servi de reliure et potentiellement dangereux pour l’environnement et la santé humaine, et une pollution diffuse, due à la présence des encres également potentiellement dangereux pour l’environnement et la santé humaine. Non maitrisé, cette gestion pourrait être un véritable problème dans les villes des pays en voie de développement. Dans un contexte où les quantités de déchets papier-cartons suivent la croissance démographique et que le bois-énergiediminuent du fait de la désertification et déforestation, le présent travail vise globalement àproposer une alternative écologique à la coupe du bois de chauffe par la valorisation énergétiquedes déchets papiers et cartons afin de contribuer à l’amélioration de la gestion des déchets solides et à la lutte contre la désertification.La quantification du flux de papier carton dans la ville de Maroua via l’usage d’une méthodologie hypothético-déductive a porté sur une quantité globale de 81,7 tonnes de papiers de seconde génération rejetés vers la nature pendant tous les services dans la ville de Maroua entre 2019-2020. Pendant la même période, le recyclage des déchets papiers et cartons pour la production des briquettes pourrait faire économiser entre les importations des matières à base de papiers et le gain de séquestration de CO2, plus de 125 487,47 tonnes de CO2 à une ville sahélienne telle que celle de Maroua. La fabrication des briquettes combustibles par un procédé mécanique a permis dedéterminer leurs caractéristiques physiques d’où il ressort que leur densité moyenne est de 1,12±0,40 avec un rapport surface/volume moyen de 3595,88±19,90mm-1. Leurs caractérisations chimiques a permis de déterminer le taux d’humidité moyen à sec de 4,00±0,02%, et un taux de carbones fixes moyen de l’ordre de 33,24±1,31%. Le pouvoir calorifique moyen mesuré pour les combustible prétraité et optimisés est de 41,18±6,34MJ/Kg tandis que le pouvoir calorifique moyen mesuré pour les combustibles prétraité mais non-optimisés est de 12,65MJ/Kg. Les briquettes composées de papier-cartons (90-98%) et plastique (2-10%) émettent du CO (1300-2110ppm), CO2(0-1,99%) en présence de l’oxygène (18,4-25%) en dessous de la norme : donc elles sont non polluantes pour l’environnement. Avec 81,7 tonnes des déchets papiers-cartons produits par an, il pourrait être produit 102,14 tonne de briquettes combustible, faisant préserver environ 153,2 tonnes de bois de cuisson. Le bénéfice économique est garanti lorsque les briquettes combustibles à base de papier carton désencrés sont vendues à 60 FCFA/kg avec un profit journalier de 11 484 FCFA/Jour
Conflits environnementaux en Afrique sahélienne : regards croisés sur les aires protégées sahéliennes camerounaises
No full textInternational audienceEn Afrique sahélienne, les aires protégées jouent un rôle central dans la conservation de la biodiversité. Cependant, leur mise en oeuvre suscite de nombreux conflits entre les communautés locales et les gestionnaires de l'environnement. Cette étude analyse les types, causes et conséquences des conflits environnementaux liés aux aires protégées sahéliennes camerounaises, en particulier dans le Parc National de Waza, la Réserve de Kalamaloué et les zones de chasse de l'Extrême-Nord. À partir d'une méthodologie qualitative basée sur des enquêtes de terrain, des entretiens semi-directifs et une revue documentaire, nous montrons que les conflits intercommunautaires (5,2 ±1,2) sont souvent exacerbés par l'exclusion des populations des ressources vitales(8,7 ±1,0), à l'inadéquation des politiques de conservation (7,9±1,4), et à l'influence des dynamiques climatiques et sécuritaires. L'analyse révèle aussi l'émergence d'initiatives communautaires et de mécanismes de gestion participative (5,9±1,9) encore embryonnaires. Les résultats soulignent la nécessité d'une gouvernance environnementale inclusive, tenant compte des réalités locales et des enjeux géopolitiques sahéliens.</div
ENVIRONMENTAL EDUCATION, MANAGEMENT OF PLANT RESOURCES FOR COOKING AND CLIMATE CHANGE PERCEPTIONS IN SAHEL
No full textInternational audienceThe author, aware of the current environmental challenges, wrote this book to raise awareness about the impact of daily practices, particularly the use of plant resources for cooking, on the environment and climate. It fits into a global context marked by deforestation and poor management of natural resources. The objective is to inform and propose concrete strategies for better management of so-called invasive plant resources, with a strong emphasis on environmental education. This book is intended for students, researchers, professionals, and nature enthusiasts, providing them with tools to take effective action. The author expresses gratitude to the NGO *Sahel Nature Consulting for Communities* for its support, as well as to those who contributed to data collection and proofreading. Finally, this book is an invitation to rethink our cooking practices, adopt more sustainable methods, and recognize the crucial importance of managing plant resources in the fight against climate change. The author hopes to inspire new initiatives towards a future that is more respectful of the environment
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Comparative Study of the Impacts Resulting from Failures in the Municipal Solid Waste Management System in the Sudano-Sahelian Cities of Cameroon and Associated Environmental Impacts
No full textInternational audienceThe study analyzes the failures of municipal solid waste management systems in the Sudano-Sahelian cities of Cameroon (Maroua, Garoua, and Kousséri) and assesses their environmental impacts. By combining quantitative and qualitative approaches, we demonstrate that the lack of adequate infrastructure, insufficient community awareness, and the inadequacy of effective public policies contribute to adverse consequences for public health, as well as for soil quality, air quality, and water resources. The findings reveal a strong correlation between systemic management dysfunctions and the uncontrolled accumulation of waste, thereby promoting pollution, the spread of diseases, and ecosystem degradation. Based on a comparative diagnostic assessment, practical recommendations are proposed to strengthen local waste management structures, promote circular economy principles, and implement integrated waste management policies.</div
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Heatwave Intensification in the Cameroonian Sahelian Zones: Biodiversity Survival Index, Required Vegetation Cover Standards in Human-Settled Environments, and Community Resilience Capacities
No full textInternational audienceRecent extreme heatwaves in the Sahel, with maximum temperatures exceeding 45 °C, are exposing biodiversity, human populations, and agricultural systems to severe thermal stress. This article synthesizes recent climatic evidence demonstrating the intensification of heatwaves in the region. It proposes a methodological framework combining in situ observations, remote sensing, and modeling to estimate a Biodiversity Survival Index (BSI) under 35-45 °C temperature scenarios. The results indicate that operational vegetation cover standards for human-inhabited environments (defined through minimum thresholds and desirable target levels) can significantly reduce urban and periurban heat island effects and enhance overall resilience. Practical and policy-oriented recommendations are provided to strengthen community resilience, including agroforestry practices, water resource management, climate-sensitive urban planning, and early warning systems. The evidence further suggests that the intensity and frequency of recent heat extremes would not have occurred without anthropogenic climate forcing, and that substantial gains in local heat mitigation can be achieved through vegetationbased strategies and strengthened local governance.</div
Hausses caniculaires en zones sahéliennes camerounaises : indice de survie de la biodiversité, normes requises du couvert végétal en milieux habités et capacités de résilience communautaire
No full textInternational audienceLes récentes vagues de chaleur extrême dans le Sahel, avec des maxima dépassant 45 °C, exposent la biodiversité, les habitants et les systèmes agricoles à des stress thermiques sévères. Cet article propose une synthèse des preuves climatiques récentes montrant l’intensification des canicules dans la région. Un protocole méthodologique combinant observations in situ, télédétection et modélisation pour estimer un Indice de Survie de la Biodiversité (ISB) face à des scénarii 35–45 °C. Les résultats montrent que des normes opérationnelles de couvert végétal pour milieux habités (seuils minimaux et cibles souhaitables) permettent de réduire l’îlot de chaleur et d’améliorer la résilience Des recommandations pratiques et politiques pour renforcer la résilience communautaire (agroforesterie, gestion de l’eau, aménagements urbains et systèmes d’alerte). Les preuves montrent que l’intensité et la fréquence des épisodes chauds récents ne seraient pas survenues sans le forçage climatique anthropique, et que des gains substantiels en atténuation locale de la chaleur peuvent être obtenus par des stratégies basées sur la végétation et la gouvernance locale
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