59 research outputs found
A data report on the effect of terrain types on the windcatcher's performance
No full textThree-dimensional steady CFD simulations were conducted to produce the numerical raw data, including the ventilation performance indexes, to investigate the natural ventilation capability of a bidirectional windcatcher in the presence of the free wind stream disturbed by the different types of terrain. In order to produce the data, a step-by-step process was followed. The generated geometry of the building model along with its two-sided windcatcher (in Rhino) was imported into the Hexpress software to build up the computational grid and finally it was fed to ANSYS Fluent to run the simulations following the predefined numerical solution settings. The calculated simulations produced the flow field and temperature distribution inside the generic building exposed to the wind flow with a reference wind speed of 3.1 m/s at the reference height of 10 m (wind condition of the city of Nottingham, the UK). The effect of four various ground surface features (open, rough, suburban and urban areas) and two different thermal scenarios (outdoor temperatures of 21.5 ºC and 26 ºC) on the wind flow and indoor thermal conditions was studied. The reported numerical data contributes to future numerical and experimental investigations toward aerodynamic design improvements for the windcatchers
Development of an artificial neural network model to predict the windcatcher (Badgir) performance
No full textAbstract: The building sector is one of the main players in the global energy market. Passive strategies such asnatural ventilation are promising techniques toward sustainable targets in this sector. Windcatchers as a natural ventilation system can provide fresh air and improve thermal comfort. However, the performance evaluation of windcatchers is still a main challenge for architectures due to the complexity of numerical methods. Thus, this study aims to develop an artificial neural network model trained by computational fluid dynamics results which can estimate the performance of the windcatcher. The accuracy of the developed model showed that it is a reliable tool to predict the performance of windcatchers with respect to design and environmental parameters.Commmunication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023
Two-sided windcatcher in low wind speed environment
No full textGlobal warming is a major threat and is mainly caused by emission of greenhouse gases. The building construction sector or buildings are accountable for about 40% of total greenhouse gases due to energy consumption. The application of air conditioning systems is reported to reach 70% of this energy consumption. In contrast, natural ventilation systems such as windcatcher are a promising passive cooling alternative that not only improve indoor air quality (IAQ) and thermal comfort but also reduce energy consumption. However, the efficiency of windcatcher is hindered by two factors: air short-circuit phenomenon and low ambient wind speed. The aim of this research is to develop a new windcatcher design that addresses both problems by integration of wing wall and installation of a new device called anti-short circuit device (ASCD). Based on review of literature, wing wall and ASCD can enhance the performance of windcatcher in low wind speed. To achieve this aim, two methods namely wind tunnel testing and simulation using computational fluid dynamics (CFD) were explored. The results showed that the difference between the CFD and experimental results was within the acceptable range. Integration of wing wall and ASCD to the windcatcher improved the IAQ factors such as air flow rate, air change rate and air velocity. It was observed that the ventilation performance of the new design in 45o wind incident angle was better than the 0o wind incident angle. In conclusion, this study has proven that the new design can effectively be implemented to improve the ventilation and IAQ
The simulation of comfort of residential apartment by computational fluid dynamics simulation
No full textWind tunnel and numerical data on the ventilation performance of windcatcher with wing wall
No full textThe data presented in this article were the basis for the study reported in the research articles entitled "Evaluation of a two-sided windcatcher integrated with wing wall (as a new design) and comparison with a conventional windcatcher" (P. Nejat, J.K. Calautit, M.Z.A. Majid, B.R. Hughes, I. Zeynali, F. Jomehzadeh, 2016) [1] which presents the effect of wing wall on the air flow distribution under using the windcatchers as a natural ventilation equipment. Here, we detail the wind tunnel testing and numerical set-up used for obtaining the data on ventilation rates and indoor airflow distribution inside a test room with a two-sided windcatcher and wing wall. Three models were integrated with wing wall angled at 30°, 45° and 60° and another windcatcher was a conventional two-sided device. The computer-aided design (CAD) three-dimensional geometries which were produced using Solid Edge modeler are also included in the data article
Curing Cholera: Pathogens, Places and Poverty in South Asia
No full textIn this paper I will seek to provide a new understanding of endemicity of disease in India. Through a study of cholera research in the twentieth century I will argue that disease and its endemicity has to be understood in biological factors as well as within a wider social and economic context. I will discuss the medical efforts at locating the causality of cholera from the nineteenth century in Indian climate, water bodies and human anatomy to show that cholera is no more a biological phenomena than water is an ecological or environmental problem. Both are essentially political and economic questions
Noncooperative Foundations of the Area Monotonic Solutions.
No full textGiven a finite set of alternatives, players alternate making offers. Player one offers some alternative that player two can accept or veto. If player two accepts, it is enforced and the game ends. Otherwise, player two makes a counteroffer among the remaining alternatives and so on. If all alternatives are vetoed, a disagreement alternative is enforced. First, the author characterizes the unique outcome of any subgame perfect equilibrium of this game. Then, the author shows tha t this outcome converges to the area monotonic solution if the alternatives are uniformly distributed over the bargaining set and a s the number of alternatives tends to infinity. Copyright 1993, the President and Fellows of Harvard College and the Massachusetts Institute of Technology.
A Novel Effective Lightweight Homomorphic Cryptographic Algorithm for data security in cloud computing
No full textCloud computing is a technology in which the resources are delivered as services. Users can access them anywhere, anytime via the Internet without any need to know the infrastructure knowledge, experience, or even authority that provides such services. It has become an important medium for enterprises to develop their networks because of these resources. With the growing need for cloud computing, security is becoming important for both individuals and business needs. Many researchers have studied the security of cloud computing. Still, security gaps or threats are increasing as the demand for cloud computing connectivity increases. Because a third party mostly provides cloud platforms to the cloud client, data protection in the cloud is the primary issue. This paper presents a novel, effective lightweight homomorphic cryptographic algorithm which contains two layers of encryption. The first layer uses the new effective, light-weight cryptographic algorithm and the second layer multiplicative homomorphic schemes considered for improving security data in cloud computing. This approach offers both symmetric and asymmetric cryptography features. The proposed approach's performance is evaluated using a variety of metrics, including memory, computational time and (key sensitivity), statistical analysis, image histogram, and entropy change analysis. The proposed algorithm's experimental findings showed a high level of security and an apparent improvement in encryption execution time, memory usage, and throughput. When compared to the cryptographic systems widely used in cloud computing. © 2022 The Author
Targeted drug delivery.
No full textAchieving adequate dosage of a drug to be effective, without crossing the line into toxicity, can be a problem. This paper reviews ongoing research into methods of delivering drugs only to diseased tissue or cells, minimally affecting surrounding tissue. In particular, the author discusses encapsulating drugs in liposomes (artificial phospholipid microcapsules) which will only bind to certain cells
Passive cooling and natural ventilation by the windcatcher (Badgir): An experimental and simulation study of indoor air quality, thermal comfort and passive cooling power
No full textThe upper wing wall can be integrated into the windcatcher to prevent direct solar and rain penetration. The impact of this combination was not considered in previous studies. Moreover, analyzing adaptive thermal comfort is another gap that was not addressed by preceding windcatcher studies, particularly for the tropical climate. Therefore, the current research aims to evaluate a two-sided windcatcher incorporated with the upper wing wall from two views: indoor air quality (IAQ) and adaptive thermal comfort. A small-scale model was tested in the wind tunnel. Next, CFD models were validated against experimental data with a good agreement between the two methods. Windcatchers with different upper wing wall lengths ranging between 10 cm and 50 cm were assessed. The results showed that the length increase led to a slight increase in the ventilation rate, and the best performance was seen in the 50 cm configuration. Subsequently, IAQ and adaptive thermal comfort were evaluated at different wind speeds of this climate. The results demonstrated that even in wind speeds below the annual average (2.5 m/s), the windcatcher performance can still satisfy IAQ parameters such as airflow rate and air change rate, recommend by CIBSE Guide A. In addition, based on the simulated conditions the results showed that wind speed from 2.5 m/s to 4 m/s could provide thermal comfort within 50%-80% of the ventilated space. Finally, the estimation of passive cooling power showed that windcatcher could provide a maximum (9.6 kW) cooling power if the wind speed is at 4 m/s and outdoor temperature at 23 °C.The first author would like to thank the Advanced Building and Environment Research (ABER) center.Scopu
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