Atmospheric Condensation Potential of Windows in Hot, Humid Climates

In hot, humid climates, the internal surfaces of windows in air-conditioned buildings are in contact with relatively colder air. Meanwhile, the external surfaces are exposed to hot humid atmospheric air. This hygro-thermal condition may cause frequent atmospheric condensation on external surfaces of windows when their surface temperature drops below the dew point temperature of the hot humid air. To date, external surface condensation on windows has been given relatively much less importance than their internal surface condensation. In addition, the thermal analysis of windows in hot humid climates has always been performed in the absence of condensation. Under moderate air temperature and humidity conditions, such practice is acceplable. However, when windows experience atmospheric condensation on their external surfaces, the effect of condensation on window energy loss needs to be examined. In this paper, the external condensation process is analyzed and the atmospheric water vapor mass condensation rate has been obtained by utilizing a simplified transient uni-dimensional finite difference model. The results show that this model has enhanced the assessment of the potential for atmospheric condensation on windows in hot, humid climates and in predicting the amount of condensation expected, as well as the associated energy loss for given thermal and moisture conditions. The numerical computation of the model is able to account for condensation and its impact on the temperature gradient across the window. Thermal analysis of both single and insulated double-glazed windows under condensation conditions is presented. The work also includes the computational procedure used and the results or a case study demonstrating the model's capabilities

USCID fourth international conference

Presented at the Role of irrigation and drainage in a sustainable future: USCID fourth international conference on irrigation and drainage on October 3-6, 2007 in Sacramento, California.Includes bibliographical references.Experiences establishing Water User Associations (WUAs) in Egypt have been carried out for the past 15 years, with increasingly promising results. Most of these activities have been pilot projects aiming to demonstrate the benefits and sustainability of WUAs. They were consequently implemented through a centralized and resource-intensive process and focused on limited numbers of associations. Since 2003, the Ministry of Water Resources and Irrigation (MWRI) has adopted as policy the large-scale development of Branch Canal WUAs. With support from USAID, about 600 branch canal WUAs (BCWUAs) have since been established, covering 15% of Egypt's irrigated area and involving half a million farmers and residents. In order to achieve this impressive outcome, a different approach has been developed and implemented, emphasizing the direct involvement of MWRI field staff and a partnership between water users and MWRI managers. This paper also argues that the conventional approach of forming WUAs by focusing on water users, and empowering them to take over the O&M responsibilities of irrigation systems, is not adapted to the Egyptian context

Atmospheric Condensation Potential of Windows in Hot, Humid Climates

In hot, humid climates, the internal surfaces of windows in air-conditioned buildings are in contact with relatively colder air. Meanwhile, the external surfaces are exposed to hot humid atmospheric air. This hygro-thermal condition may cause frequent atmospheric condensation on external surfaces of windows when their surface temperature drops below the dew point temperature of the hot humid air. To date, external surface condensation on windows has been given relatively much less importance than their internal surface condensation. In addition, the thermal analysis of windows in hot humid climates has always been performed in the absence of condensation. Under moderate air temperature and humidity conditions, such practice is acceplable. However, when windows experience atmospheric condensation on their external surfaces, the effect of condensation on window energy loss needs to be examined. In this paper, the external condensation process is analyzed and the atmospheric water vapor mass condensation rate has been obtained by utilizing a simplified transient uni-dimensional finite difference model. The results show that this model has enhanced the assessment of the potential for atmospheric condensation on windows in hot, humid climates and in predicting the amount of condensation expected, as well as the associated energy loss for given thermal and moisture conditions. The numerical computation of the model is able to account for condensation and its impact on the temperature gradient across the window. Thermal analysis of both single and insulated double-glazed windows under condensation conditions is presented. The work also includes the computational procedure used and the results or a case study demonstrating the model's capabilities

Adrenal Hemangioma: Findings at Multidetector CT with Short Review of the Literature

We present the computed tomography (CT) imaging findings of a 44-year-old male with incidentally discovered right adrenal hemangioma displaying imaging pattern of nonadenomatous pattern, associated with multiple hepatic hemangiomata using 64-slice multidetector scanner with reviewing published CT imaging findings with short review of the literature

Sensitivity Analysis and Modeling for DEM Errors

The Digital Elevation Model (DEM) can be created using airborne Light Detection And Ranging (LIDAR), Image or Synthetic-Aperture Radar (SAR) mapping techniques. The direct georeferencing of the DEM model is conducted using a GPS/inertial navigation system. The airborne mapping system datasets are processed to create a DEM model. To develop an accurate DEM model, all errors should be considered in the processing step. In this research, the errors associated with DEM models are investigated and modeled using Principal Component Analysis (PCA) and the least squares method. The sensitivity analysis of the DEM errors is investigated using PCA to define the significant GPS/inertial navigation data components that are strongly correlated with DEM errors. Then, the least squares method is employed to create a functional relationship between the DEM errors and the significant GPS/inertial navigation data components. The DEM model errors associated with airborne mapping system datasets are investigated in this research. The results show that the combined PCA analysis and least squares method can be used as a powerful tool to compensate the DEM error due to the GPS/inertial navigation data with about 27% in average for DEM errors produced by the direct georeferenced airborne mapping system