Procédé de l’étude de la rupture des fibres à partir d’un essai en traction sur mèches

Le travail consiste à solliciter en traction des mèches de fibres de verre, en utilisant l’émission acoustique pour suivre en temps réel l’endommagement du matériau. En effet, les ruptures de fibres s’accompagnent de libération d’énergie sous formes d’ondes acoustiques, qui sont localisés et analysés ensuite. Les objectifs sont de suivre en temps réel par émission acoustique les ruptures de fibres et les localiser dans un premier temps, et de caractériser le comportement des fibres en fin de vie, afin de comparer les résultats avec les autres travaux. Deux types d’essais doivent être réalisés, ceci afin de pouvoir comparer les méthodes et les résultats avec ceux déjà obtenus. La procédure expérimentale est un aspect primordial des essais sur mèches, au niveau de la réalisation des échantillons et tout au long de l’essai. Des essais de traction devront être réalisés sur des mèches de 1000 fibres de verre E de longueur de jauge 60 mm ; ensuite les mèches seront lubrifiées par du pétrole avant la mise en charge, afin de réduire les frictions entre fibres, d’éviter les ruptures en cascade, et de favoriser la propagation des ondes. Deux capteurs résonnants placés aux extrémités de l’éprouvette permettent de détecter l’onde acoustique émise par la rupture d’une fibre, et de la transformer en signal électrique.Mots clés : fibres de verre E, résine, rupture, essai en traction, capteurs résonants, extensomètre

EVALUATING THE PERFORMANCE OF SOME LOCAL AND IMPORTED EMITTERS TO IMPROVE THEIR HYDRAULIC PERFORMANCE

Due to the climatic changes in Egypt, the remarkable population growth and the high demand for water, especially for irrigation water. To rationalize the use of irrigation water, it has been  applied efficient irrigation systems such as trickle irrigation system for irrigating trees and plants by securing the least amount of water for the plant without wasting and saturation of the surrounding area. This study aims to evaluate the performance of some local and imported emitters. In this study, 16 emitters were used (9 imported emitters and 7 local emitters) divided into (9 non-pressure compensating and 7 pressure compensating), for evaluation under different operating pressures (0.5, 0.75, 1, 1.25 and 1.5 bar), in addition to measure the hydraulic performance of the manufacture's coefficient of variation (CV %), emitter flow variation (     %), and the emission uniformity (EU %). The results showed that the highest emission uniformity value for emitters of (OT1, OT2, KF, TKY, CKF and OT3), with discharge of (2) L / h non- pressure compensating (NPC), 4 l/h non-pressure compensating (NPC), 4 l / h pressure compensating (PC), 8 l/ h non- pressure compensating (NPC),  8 l / h pressure compensating (PC) and 16 l / h non-pressure compensating (NPC) respectively, while, the lowest manufacture's coefficient of variation value (CV%), emitter flow variation (     %) were used with 6  emitters in the second part of the laboratory experiment to evaluate the side lines under the length of the hoses (50, 75, 100 m) at a distance between the emitters (4 m), for the calculation of the emission uniformity (EU%), friction  losses and consumption of power. From the last result in laboratory and through evaluation the 6 emitters under study in terms of prices and emission uniformity (EU%), a randomized field study was conducted on the farms where the three emitters (OT2, KF and OT1) under lateral length (50 m) and emitter spacing (4 m). The purpose of the field test was carried out to determine the degree of clogging throughout the operating period (after 2 and 4 years). A field test used an emitter (OT1, OT2 and KF) found for two months and has been used again for two years when farming in the farm was expanded and used four years ago by expanding the farm, the emitter (OT2) clogging ratio was 3.09% within two months, 6.95% within two years and 10.49% within 4 years, the emitter (OT1) clogging ratio was 5.26% within two months, 11.11% within two years and 17.64% within 4 years, the emitter (KF) clogging ratio was 6.83% within two months, 13.63% within two years and 20.96% within 4 years. The results showed that the lowest degree of clogging ratio of the emitter (OT2) was within two months of operation. In general, and as expected, the results indicate that clogging ratio increased with increasing the time of installation of the field emitter and the range of factors affecting the periodic maintenance and design of good and components of irrigation network with high quality and ratio of manufacture's coefficient of variation (CV%)

Modern insulation materials for warming of walls

Biodiversity hotspots understandably attract considerable conservation attention. However, deserts are rarely viewed as conservation priority areas, due to their relatively low productivity, yet these systems are home to unique species, adapted to harsh and highly variable environments. While global attention has been focused on hotspots, the world's largest tropical desert, the Sahara, has suffered a catastrophic decline in megafauna. Of 14 large vertebrates that have historically occurred in the region, four are now extinct in the wild, including the iconic scimitar-horned oryx (Oryx dammah). The majority has disappeared from more than 90% of their Saharan range, including addax (Addax nasomaculatus), dama gazelle (Nanger dama) and Saharan cheetah (Acinonyx jubatus hecki) - all now on the brink of extinction. Greater conservation support and scientific attention for the region might have helped to avert these catastrophic declines. The Sahara serves as an example of a wider historical neglect of deserts and the human communities who depend on them. The scientific community can make an important contribution to conservation in deserts by establishing baseline information on biodiversity and developing new approaches to sustainable management of desert species and ecosystems. Such approaches must accommodate mobility of both people and wildlife so that they can use resources most efficiently in the face of low and unpredictable rainfall. This is needed to enable governments to deliver on their commitments to halt further degradation of deserts and to improve their status for both biodiversity conservation and human well-being. Only by so-doing will deserts be able to support resilient ecosystems and communities that are best able to adapt to climate change. © 2013 John Wiley & Sons Ltd

Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993-2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTISD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTISD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTISD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming.Peer reviewe

Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993-2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTISD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTISD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTISD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming

The future distribution of wetland birds breeding in Europe validated against observed changes in distribution

Wetland bird species have been declining in population size worldwide as climate warming and land-use change affect their suitable habitats. We used species distribution models (SDMs) to predict changes in range dynamics for 64 non-passerine wetland birds breeding in Europe, including range size, position of centroid, and margins. We fitted the SDMs with data collected for the first European Breeding Bird Atlas and climate and land-use data to predict distributional changes over a century (the 1970s-2070s). The predicted annual changes were then compared to observed annual changes in range size and range centroid over a time period of 30 years using data from the second European Breeding Bird Atlas. Our models successfully predicted ca. 75% of the 64 bird species to contract their breeding range in the future, while the remaining species (mostly southerly breeding species) were predicted to expand their breeding ranges northward. The northern margins of southerly species and southern margins of northerly species, both, predicted to shift northward. Predicted changes in range size and shifts in range centroids were broadly positively associated with the observed changes, although some species deviated markedly from the predictions. The predicted average shift in core distributions was ca. 5 km yr(-1) towards the north (5% northeast, 45% north, and 40% northwest), compared to a slower observed average shift of ca. 3.9 km yr(-1). Predicted changes in range centroids were generally larger than observed changes, which suggests that bird distribution changes may lag behind environmental changes leading to 'climate debt'. We suggest that predictions of SDMs should be viewed as qualitative rather than quantitative outcomes, indicating that care should be taken concerning single species. Still, our results highlight the urgent need for management actions such as wetland creation and restoration to improve wetland birds' resilience to the expected environmental changes in the future

Risk of biodiversity collapse under climate change in the Afro-Arabian region

Abstract For 107 endemic mammal species in the Afro-Arabian region, Sahara-Sahel and Arabian Desert, we used ensemble species distribution models to: (1) identify the hotspot areas for conservation, (2) assess the potential impact of the projected climate change on the distribution of the focal species, and (3) assign IUCN threat categories for the focal species according to the predicted changes in their potential distribution range. We identified two main hotspot areas for endemic mammals: the Sinai and its surrounding coastal area in the East, and the Mediterranean Coast around Morocco in the West. Alarmingly, our results indicate that about 17% of the endemic mammals in the Afro-Arabian region under the current climate change scenarios could go extinct before 2050. Overall, a substantial number of the endemic species will change from the IUCN threat category “Least Concern” to “Critically Endangered” or “Extinct” in the coming decades. Accordingly, we call for implementing an urgent proactive conservation action for these endemic species, particularly those that face a high risk of extinction in the next few years. The results of our study provide conservation managers and practitioners with the required information for implementing an effective conservation plan to protect the biodiversity of the Afro-Arabian region

Monitoring of the endemic Sinai Baton Blue butterfly Pseudophilotes sinaicus in the St Katherine Protectorate, South Sinai

Results of the monitoring of the Sinai Baton Blue butterfly in its stronghold of Farsh Shoeib on Gebel Safsafa in the St Katherine Protectorate between 2004-9 is analysed to compare them with the detailed study of Mike James in 2002-3. The butterfly appears to have a three-year population cycle, with its population crashing regularly to very low levels. The conservation implications are discussed

A pilot study to survey the carnivore community in the hyper-arid environment of South Sinai mountains

Carnivores are one of the taxa most affected by habitat fragmentation and human persecution; as a result, most carnivore species are declining; for this reason monitoring changes in carnivore population is paramount to plan effective conservation programs. Despite being one of the most threatened habitat, arid environment are often neglected and the carnivore species living in this environment are generally poorly studied. We conducted a pilot study to survey the carnivore guild in the St Katherine Protectorate, the largest Egyptian national park and a hotspot for biodiversity and conservation in an arid environments. Three species were detected using both camera trapping and morphological identification of scats: Red fox, Striped hyena and Arabian wolf, while through genetic analysis we were able to confirm the presence of Blandford fox as well. Arabian wolf appeared to be the most elusive and rarer species and should be a conservation priority. We also provide guidelines for a monitoring program: we estimated that a survey period of 8-10 weeks would be enough to detect foxes and hyenas with a 95% probability, but it would take at least 26 weeks to detect the presence of wolves. This is the first comprehensive carnivore survey in South Sinai and provides an important baseline for future studies in this unique hyper-arid environment at the conjunction between the African and Eurasian continents