Affiner votre recherche
Résultats 1-6 de 6
Running water in gestating sows boxes | Lamina de agua en corrales de gestacion para suinos
1998
Lagana, Christine | Nass, Irenilza de A. | Tolon Barrios, Yamilia (Universidad de Campinas, (Brasil).Dept. de Construcoes Rurais)
La mayoria de los problemas relacionados con la produccion de cerdas gestantes, criadas en confinamiento, en climas calientes, es debido al estres por las altas temperaturas. El acceso al agua permite que sea alcanzada la sensacion de confort termico; el objetivo principal de este trabajo fue interpretar el comportamiento de las cerdas gestantes en el sistema que utiliza una lamina de agua corriente en los corrales, permitiendo de esta forma el acceso constante al agua como fuente de intercambio termico y confort. Fueron estudiados el efecto de dos tipos de instalaciones para cerdas en gestacion, el primer metodo fue el de piso de concreto, comparado a un segundo que utiliza un canal de agua corriente de 5 cm de profundidad y 1 m de ancho en toda la extension de la nave. Tanto el microclima como la respuesta productiva de las cerdas no tuvieron diferencias significativas, mas la sensacion de confort termico es resaltada debido a un menor numero de animales descartados
Afficher plus [+] Moins [-]Construccion reservorio de agua para riego Piscotras
1999
Défis présents et futurs pour les systèmes urbains affectés par l’eau de mer et son intrusion: le cas de Venise, Italie Desafíos actuales y futuros de los sistemas urbanos afectados por agua salada y su intrusión: el caso de Venecia, Italia 受 海水及其入侵影响的城市系统研究现状及展望---以意大利威尼斯为例 Desafios presentes e futuros dos sistemas urbanos afectados por água marinha e sua intrusão: o caso de Veneza, Itália | Present and future challenges of urban systems affected by seawater and its intrusion: the case of Venice, Italy Texte intégral
2011
In lagoonal and marine environments, both historic monuments and recent buildings suffer from severe salt damage caused by sea flooding, sea-level rise and frequent storm events. Salt-water contamination of groundwater systems, a widespread phenomenon typical of coastal areas, can lead to a deterioration not only of the quality of fresh groundwater resources, but also of building materials in urban settlements. A general overview is given of the hydrogeological configuration of the subsoil of Venice (Italy), with particular reference to the shallow groundwater circulation. The relationship between the seawater in the subsoil and salt decay processes, due to salt crystallization, is highlighted. These processes affect civil constructions in Venice’s historic center. Perched aquifers, influenced by tide variations and characterized by salt-water intrusion, favor the transport of salts within masonry walls through the action of rising damp. In fact, foundations, in direct contact with the aquifers, may become a preferential vehicle for the transportation of salt within buildings. Decay patterns of different building materials can be detected through non-destructive techniques, which can identify sea-salt damage and therefore assist in the preservation of cultural heritage in coastal areas.
Afficher plus [+] Moins [-]Review: Occurrence of the pathogenic amoeba Naegleria fowleri in groundwater | Revue: Présence de l’amibe pathogène Naegleria fowleri dans les eaux souterraines Revisión: Presencia de la ameba patógena Naegleria fowleri en el agua subterránea 回顾 : 地下水中的致病性变形虫—福氏纳格里阿米巴原虫 Revisão: Ocorrência do patógeno ameba Naegleria fowleri em águas subterrâneas Texte intégral
2017
Bright, Kelly R. | Gerba, Charles P.
Naegleria fowleri is a thermophilic free-living amoeba found worldwide in soils and warm freshwater. It is the causative agent of primary amebic meningoencephalitis, a nearly always fatal disease afflicting mainly children and young adults. Humans are exposed to the organism via swimming, bathing, or other recreational activity during which water is forcefully inhaled into the upper nasal passages. Although many studies have looked at the occurrence of N. fowleri in surface waters, limited information is available regarding its occurrence in groundwater and geothermally heated natural waters such as hot springs. This paper reviews the current literature related to the occurrence of N. fowleri in these waters and the methods employed for its detection. Case reports of potential groundwater exposures are also included. Despite increased interest in N. fowleri in recent years due to well-publicized cases linked to drinking water, many questions still remain unanswered. For instance, why the organism persists in some water sources and not in others is not well understood. The role of biofilms in groundwater wells and plumbing in individual buildings, and the potential for warming due to climate change to expand the occurrence of the organism into new regions, are still unclear. Additional research is needed to address these questions in order to better understand the ecology of N. fowleri and the conditions that result in greater risks to bathers.
Afficher plus [+] Moins [-]Review: Impact of underground structures on the flow of urban groundwater | Revue: Impact des structures du sous-sol sur les écoulements des eaux souterraines en milieu urbain Revisión: Impacto de las estructuras del subsuelo en el flujo del agua subterránea en zonas urbanas 评论:地下结构对城区地下水流的影响 Revisão: Impacto de estruturas subterrâneas no fluxo das águas subterrâneas urbanas Texte intégral
2016
Attard, Guillaume | Winiarski, Thierry | Rossier, Yvan | Eisenlohr, Laurent
Property economics favours the vertical development of cities but flow of groundwater can be affected by the use of underground space in them. This review article presents the state of the art regarding the impact of disturbances caused by underground structures (tunnels, basements of buildings, deep foundations, etc.) on the groundwater flow in urban aquifers. The structures built in the underground levels of urban areas are presented and organised in terms of their impact on flow: obstacle to the flow or disturbance of the groundwater budget of the flow system. These two types of disturbance are described in relation to the structure area and the urban area. The work reviewed shows, on one hand, the individual impacts of different urban underground structures, and on the other, their cumulative impacts on flow, using real case studies. Lastly, the works are placed in perspective regarding the integration of underground structures with the aim of operational management of an urban aquifer. The literature presents deterministic numerical modelling as a tool capable of contributing to this aim, in that it helps to quantify the effect of an underground infrastructure project on groundwater flow, which is crucial for decision-making processes. It can also be an operational decision-aid tool for choosing construction techniques or for formulating strategies to manage the water resource.
Afficher plus [+] Moins [-]A three-dimensional fluid-solid model, coupling high-rise building load and groundwater abstraction, for prediction of regional land subsidence | Modèle fluide-solide tridimensionnel, couplant la charge d’une tour d’immeuble et les prélèvements en eau souterraine, pour la prévision de la subsidence régionale Un modelo tridimensional fluido-sólido, que combina cargas de edificios de gran Altura y extracción de agua subterránea, para la predicción de subsidencia regional del terreno 高层建筑荷载和地下水开采叠加作用下区域地面沉降预测三维流固耦合模型 Um modelo fluido-sólido tridimensional, acoplando carga de edifícios altos com captação de águas subterrâneas, para previsão de subsidência regional Texte intégral
2019
Li, Zhao | Luo, Zujiang | Wang, Qi | Du, Jingjing | Lu, Wei | Ning, Di
The main factors that cause land subsidence are groundwater withdrawal and the load of high-rise buildings. Previous studies on land subsidence caused by high-rise buildings have focused on small areas. Few scholars have proposed land subsidence models that combine the effects of groundwater withdrawal and high-rise building load at a regional scale. This work was based on Biot’s consolidation theory and the nonlinear rheology theory. The soil parameters were varied in accordance with the Kozeny-Carman equation and Duncan-Zhang nonlinear model, and applied to a site in eastern China. A three-dimensional finite element method (FEM) program, fully coupling varying soil parameter values and fluid-solid characteristics of land subsidence, was coded using FORTRAN. The program was used to simulate and predict regional land subsidence and to study the coupling effects of groundwater withdrawal and high-rise building load. The results showed that the soil parameters varied in reasonable range and the trend of variation was consistent with the characteristics of soil deformation. The sum of the land subsidence under high-rise building load alone and groundwater withdrawal alone differed from land subsidence under the combined effects of groundwater withdrawal and high-rise building load. The coupling effect of land subsidence caused by high-rise building load and groundwater withdrawal was shown to be nonlinear.
Afficher plus [+] Moins [-]