593 research outputs found

    ALGORITHM OF THE SIMULATOR ON THE TOPIC “A STRAIGHT LINE IN SPACE”

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    The report considers the algorithm of the simulator on the topic “A straight line in space

    Microembossing of ultrafine grained Al: microstructural analysis and finite element modelling

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    Ultra fine grained (UFG) Al-1050 processed by equal channel angular pressing (ECAP) and UFG Al-Mg-Cu-Mn processed by high pressure torsion (HPT) were embossed at both room temperature and 300 °C, with the aim of producing micro-channels. The behaviour of Al alloys during the embossing process was analysed using finite element (FE) modelling. The cold embossing of both Al alloys is characterised by a partial pattern transfer, a large embossing force, channels with oblique sidewalls and a large failure rate of the mould. The hot embossing is characterised by straight channel sidewalls, fully transferred patterns and reduced loads which decrease the failure rate of the mould. Hot embossing of UFG Al-Mg-Cu-Mn produced by HPT shows a potential of fabrication of microelectromechanical system (MEMS) components with micro channels

    Numerical Models for Predicting the Fate of Ammonia Nitrogen for Biological Treatment Processes in Urbanized Rivers in China

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    Volume 1 • Issue 6 • 2012 found to remove over 70% of nutrients during restoration exercises. The growing technology, Biological Treatment Method (BTM) is not new to history but it is beginning to receive attention in river and wastewater treatment nowadays. The BTM has been successfully used in many countries worldwide including China for domestic and industrial wastewater treatment. For instance, the method has been used in urban streams in Shenzen, Rui'an and Wuxi of China. This method has been known to rapidly reduce the concentrations of effluent BOD and COD There is however lack of requisite mathematical algorithms to support the forecasting and monitoring of water quality variables under the BTM. Nutrient flux in urban rivers is very important for monitoring water quality. Nitrogen is one of these nutrients that promote cellular growth and thus eutrophication in water bodies. In wastewater, nitrogen has the capability to exist in different forms -ammonia, organic, nitrate and nitrite. In this particular case, the ammonia-nitrogen widely known to contribute towards eutrophication is considered. Mathematical algorithms are developed and tested to determine their predicative Keywords: Fate; Ammonia-nitrogen; Numerical models; Biological treatment method Introduction Developing economies face the challenge of poor surface water quality of water bodies. Environmental degradation coupled with industrial growth and infrastructural development further adds more challenge to water planners and managers in urban communities. China for instance, is undergoing water related challenges due to urban expansion and the rapid growing industrial activity. It is also partly because the transport of household and industrial wastewater from both point and non-point sources into rivers have increased their vulnerability and support for aquatic life Abstract One of the sustainable approaches towards polluted urbanized rivers restoration is the use of biological treatment method. The method has been successfully used in China since the past decade and has received growing recognition among university and government authorities. Field campaigns during biological treatment methods to measure water quality variables are expensive as in most water quality measurements. Therefore, the availability of mathematical models helps to provide a basis for forecasting and planning for such campaigns. Ammonia-nitrogen is a key variable supporting eutrophication of rivers. In this research, mathematical models were developed to describe the fate of ammonia-nitrogen given a set of water quality variables (i.e. transparency, water temperature, COD, DO, total nitrogen and total phosphorus). Selected six models were chosen based on adjusted R2, Akaike Information Criterion (AICc) and Bayesian Information Criterion (BIC). The selected models were tested with independent dataset. The results show that the prediction errors range from ±20% to ±36%. The errors found in this research are comparable to previous studies and are considered to be largely due to the large sampling and measurement errors usually encountered in water quality testing and measurements. The results in this research support on-going numerical modelling in wastewater treatment, water quality modelling and water resources planning and management

    Households’ Livelihood Vulnerability to Climate Change and Climate Variability: A Case Study of the Coastal Zone, The Gambia

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    Climate change and its variability are negatively influencing climate-dependent activities such as agriculture and fishing in Africa, of which The Gambia is no exception. Households are vulnerable to its impacts. With the impacts of climate change and its variability in The Gambia, livelihoods of people will be negatively affected. There is the need to know which regions are more vulnerable than others are so livelihood improvement actions can be taken in areas they are needed the most in the wake of present and future climate change impacts, thus, the objective of this study. This will aid in eluding maladaptation and waste of limited developmental resources for climate change adaptation. The results of the study will also assist the Government and other development partners in making decisions that are more informed as to areas where and the kind of assistance needed between the districts in the coastal zone of The Gambia. The study employed the Livelihood Vulnerability Index (LVI) in the estimation of household vulnerability to Climate Change (CC) and its variability based on their: Socio-Demographic Profile; Livelihood strategies; Social Networks; Health; Water; Natural disasters and Climate Variability and; Knowledge and Skills. This approach is divided into the Intergovernmental Panel on Climate Change (IPCC) three main components of vulnerability, namely: Exposure; Sensitivity and; Adaptive Capacity. The primary data used is based on a survey of 355 household heads in agriculture or fishing activities in the coastal zone of The Gambia, while the secondary data used was on rainfall and temperature. Microsoft Office Excel 2016 was the software employed in estimating the livelihood vulnerability index, developing the vulnerability spider (radar) chart and the vulnerability triangle in this study. The findings of the study reveal households in Kombo South may be more vulnerable to climate change and its variability than Lower Niumi districts in the study area. The LVI revealed Kombo South district may be more vulnerable to: Health; Food and; Knowledge and Skills while Lower Niumi district is more vulnerable to: Socio-Demographic Profile; Livelihood Strategies; Social Networks; Water and; Natural Disasters and Climate Variability. The overall LVI-IPCC main components of vulnerability reveals households in Kombo South may be more vulnerable than households in Lower Niumi district in the coastal zone of The Gambia. Keywords: Vulnerability, Climate Change, Climate Variability, Livelihood Vulnerability Index, Coastal Zone, Households, Farmers, The Gambi

    Subsurface chlorophyll maximum and hydrodynamics of the water column

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    The vertical distributions of chlorophyll a (in vivo fluorescence) and hydrodynamic properties were monitored in the Gulf of St. Lawrence (Canada) from 6 to 10 August 1983, using an automatic yo-yo profiling system and a chain of 4 current meters. Spectral analyses of temperature and in vivo fluorescence series showed that dominant frequencies were associated with internal waves (∼16 h inertial frequency). A subsurface chlorophyll maximum was continuously observed in the lower part of the 20 m thick photic layer, at a depth corresponding with maximum vertical stability of the water column, just above the nutricline.The depth of maximum phytoplankton production, at least on sunny days, corresponded to that of the subsurface chlorophyll maximum and of the maximum in vertical stability. This close association persisted despite strong horizontal advection and vertical movements caused by internal waves. Photosynthetic adjustment did occur in the water column: higher vertical stability at depth favored shade adaptation of the phytoplankton in the layer of maximum stability, as compared to the more light-adapted cells of the upper well-mixed layer. At our sampling station, vertical turbulent diffusion seemed to be high enough to replenish nutrients in the photic layer, so that they never became completely exhausted, even in surface waters. Therefore, the observed subsurface chlorophyll maximum not only resulted from environmental conditions more favorable for phytoplankton accumulation and growth, but it also involved active photosynthetic responses of phytoplankton

    Aménagements hydro-agricoles et santé (vallée du fleuve Sénégal)

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    Près de 1 500 personnes résidant dans les villages rattachés au périmètre irrigué MO 6bis (périmètre de Diomandou, département de Podor) ont fait l'objet de prélèvements d'urine et/ou de selle afin de déterminer la prévalence de la bilharziose urinaire, de la bilharziose intestinale ainsi que des autres parasitoses entériques. Chez les riverains du périmètre, 1 295 urines ont été examinées, parmi lesquelles sept contenaient des oeufs viables de #Schistosoma haematobium,cequirepreˊsenteuntauxdepreˊvalencede0,5, ce qui représente un taux de prévalence de 0,5%. L'enquête épidémiologique a montré qu'il s'agissait de cas importés. Les examens de selles ont concerné 1 181 sujets. 316 d'entre eux (soit plus de 26% des personnes examinées) hébergeaient un ou plusieurs parasites intestinaux. Un seul éliminait des oeufs de #S. mansoni, ce qui correspond à un indice d'infestation de 0,1%. Il s'agissait là aussi d'un individu dont la contamination avait eu lieu en dehors de la zone d'étude. #Eschirichia coliestlaparasiteenteˊriqueleplusreˊpanduavec17,2 est la parasite entérique le plus répandu avec 17,2% de porteurs de kystes. Les autres espèces rencontrées, à savoir #Hymenolepis nana, #Strongyloïdes stercoralis, #Ascaris lumbricoïdes et #Trichiuris trichiura$ sont rares et ne concernent qu'un peu moins de 2% des sujets examinés. Ces résultats démontrent l'absence, pour l'instant tout au moins, de foyers de transmission des bilharzioses dans les villages du périmètre de Diomandou. Le risque d'apparition de ces maladies est cependant important et dépend à la fois de l'évolution des infrastructures et de l'éventuelle apparition d'hôtes intermédiaires encore absent du réseau hydrographique de ce périmètre mis en place récemment. (Résumé d'auteur

    Vulnérabilité des troupeaux transhumants aux mutations climatiques : analyse des perceptions et adaptations locales dans le bassin de la Sota à Malanville

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    L’élevage bovin occupe une place importante parmi les activités des populations du Nord-Est du Bénin. Cette activité est très vulnérable aux mutations climatiques dans le bassin de la Sota à Malanville situé à l’extrême Nord-Est du Bénin. La présente recherche vise, d’une part, à appréhender, les perceptions des agro-éleveurs et des éleveurs sur les mutations climatiques et à analyser, d’autre part, leurs stratégies pour y faire face. Les données sur les perceptions et les stratégies d’adaptation ont été collectées au moyen d’enquêtes faites par entretiens, focus groupes et questionnaires dans cinq (5) villages choisis de manière aléatoire. Le calcul du taux moyen de réponse et l’analyse en composantes principales ont été utilisés pour analyser ces données. Les résultats montrent une grande similitude des manifestations des mutations climatiques perçues par les agro-éleveurs et éleveurs. Les manifestations les plus citées sont: la hausse des températures (citée par 99,16% des agro-éleveurs et 100% des éleveurs), les poches de sécheresse prolongée (citée par 67,5% des agro-éleveurs et 91,66% des éleveurs), les vents forts et violents (citée par 70% des agro-éleveurs et 87,08% des éleveurs). Pour ce qui concerne les effets des mutations climatiques, les agro-éleveurs et les éleveurs en perçoivent respectivement 9 et 11.Pour les premiers, les effets les plus marquants sont l’assèchement des points d’eau (80%), l’amenuisement du disponible fourrager (71,42%), la contamination et le comblement des points d’eau (65%). Pour les seconds, ce sont: l’amenuisement du disponible fourrager (96,66%), la contamination et le comblement des points d’eau (92,50%), l’assèchement précoce des points d'eau (91,50%), l’affaiblissement des animaux (57,50%), l’amaigrissement des animaux (56,66%). En réponse à cette instabilité du climat et ses effets, les agro-éleveurs et les éleveurs ont développé des stratégies dont les principales (communes aux deux groupes socio-professionnels) sont : le respect des campagnes de vaccination (citée par 85% des agro-éleveurs et 97,50% des éleveurs), l’abreuvement au fleuve ou à la rivière (citée par 37,50% des agro-éleveurs et 55% des éleveurs), la mobilité spatiale (citée par 59,50% des agro-éleveurs et 55% des éleveurs). Les résultats du test de Mann Whitney indiquent une différence significative de perception au seuil de 5% pour les effets, manifestations et stratégies communs aux deux groupes socioprofessionnelsMots-clés: mutations climatiques, perceptions et stratégies d’adaptation, agro-éleveurs et éleveurs, vulnérabilité, bassin de la Sota, Malanville. Vulnerability of transhumant herds to the climatic mutations: analysis of the perceptions and local adaptations in the watershed of Sota at MalanvilleThe bovine breeding occupies a significant place among the activities of the populations of the North-East of the Benin. This activity is very vulnerable to the climatic mutations in the watershed of Sota at Malanville located at the far North-East of Benin. This research aims, on the one hand, to understand the perceptions of the agro-pastoralists and the stockbreeders on the climatic mutations and, on the other hand, to analyze the strategies implemented by them to face there. The data on perceptions and the strategies of adaptation of the agro-pastoralists and the stockbreeders were collected using interviews, focus groups and questionnaires in five (5) villages randomly selected. The calculation of the response rate and the analysis in principal components were used to analyze the data. The results show a great similarity of the manifestations of the climatic mutations perceived by the agro-pastoralists and the stockbreeders. The most quoted manifestations are: the temperatures increase (quoted by 99.16% of the agro-pastoralists and 100% of the stockbreeders), prolonged dry spells (quoted by 67.5% of the agro-pastoralists and 91.66% of the stockbreeders), strong and violent winds (quoted by 70% of the agro-pastoralists and 87.08% of the stockbreeders). Concerning the effects of climatic mutations, the agro-pastoralists and the stockbreeders perceive respectively 9 and 11.For the firsts, the most significant effects are the drying up of the water points (80%), the dwindling of available forage (71.42%), the contamination and the filling of the water points (65%). For the seconds the main effects are: the dwindling of available forage (96.66%), the contamination and the filling of the water points (92.50%), premature drying up of the water points (91.50%), the weakening of the animals (57.50%), the slimming of the animals (56,66%). In response to this instability of the climate and its effects, the agro-pastoralists and the stockbreeders developed strategies. The main common strategies are: the respect of the vaccination campaigns (quoted by 85% of the agro-pastoralists and 97.50% of the stockbreeders), watering at the river (quoted by 37.50% of the agro-pastoralists and 55% of the stockbreeders) and spatial mobility (quoted by 59.50% of the agro-pastoralists and 55% of the stockbreeders). The results of the Mann Whitney test indicated a significant difference in perception threshold of 5% for effects, manifestations and strategies common to both socio professional groups.Keywords: climatic mutations, perceptions and strategies of adaptation, agro-pastoralists, stockbreeders, vulnerability, watershed of Sota, Malanville

    The gravity duals of SO/USp superconformal quivers

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    We study the gravity duals of SO/USp superconformal quiver gauge theories realized by M5-branes wrapping on a Riemann surface ("G-curve") together with a Z_2-quotient. When the G-curve has no punctures, the gravity solutions are classified by the genus g of the G-curve and the torsion part of the four-form flux G_4. We also find that there is an interesting relation between anomaly contributions from two mysterious theories: T_{SO(2N)} theory with SO(2N)^3 flavor symmetry and \tilde{T}_{SO(2N)} theory with SO(2N) x USp(2N-2)^2 flavor symmetry. The dual gravity solutions for various SO/USp-type tails are also studied.Comment: 27 pages, 13 figures; v2 minor corrections, typos corrected, Figure 13 replaced, references adde
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