Asymptotic solution of the low Reynolds-number flow between two co-axial cones of common apex

The paper is concerned with the axi-symmetrlc, incompressible, steady, laminar and Newtonian flow between two, stationary, conical-boundaries, which exhibit a common apex but may include arbitrary angles. The flow pattern and pressure field are obtained by solving the pertinent Navier-Stokes' equations in the spherical coordinate system. The solution is presented in the form of an asymptotic series, which converges towards the creeping flow solution as a cross-sectional Reynolds-number tends to zero. The first term in the series, namely the creeping flow solution, is given in closed form; whereas, higher order terms contain functions which generally could only be expressed in infinite series form, or else evaluated numerically. Some of the results obtained for converging and diverging flows are displayed and they are demonstrated to be plausible and informative

Prosopis juliflora leave extracts induce cell death of MCF-7, HepG2, and LS-174T cancer cell lines

Prosopis juliflora (P. juliflora) is a widespread phreatophytic tree, which belongs to the Fabaceae family. The goal of the present study is to investigate the potential anti-cancer effect of P. juliflora leave extracts and to identify its chemical composition. For this purpose, MCF-7 (breast), HepG2 (liver), and LS-174T (colorectal) cancer cell lines were cultivated and incubated with various concentrations of P. juliflora leave extracts, and its impact on cell viability, proliferation, and cell cycle stages was investigated. P. juliflora leave extracts induced concentration-dependent cytotoxicity against all tested cancer cell lines. The calculated IC50 was 18.17, 33.1 and 41.9 μg/ml for MCF-7, HePG2 and LS-174T, respectively. Detailed analysis revealed that the cytotoxic action of P. juliflora extracts was mainly via necrosis but not apoptosis. Moreover, DNA content flow cytometry analysis showed cell-specific anti-proliferative action and cell cycle stages arrest. In order to identify the anti-cancer constituents of P. juliflora, the ethyl extracts were analyzed by liquid chromatography-mass spectrometry. The major constituents identified in the ethyl extracts of P. juliflora leaves were hydroxymethyl-pyridine, nicotinamide, adenine, and poly-(methyl methacrylate) (PMMA). In conclusion, P. juliflora ethyl acetate extracts have a potential anti-cancer effect against breast adenocarcinoma, hepatocellular carcinoma, and colorectal adenocarcinoma, and is enriched with anti-cancer constituents

Two energy storage alternatives for a solar-powered sustainable single floor desert home

This paper is concerned with the thermodynamic analysis of a totally solarpowered desert home. The home is air-conditioned and provides all modern comforts and facilities. It features closely spaced, roof mounted photovoltaic modules, which collect the solar energy driving the whole energy system. During the day time, the modules form an elevated horizontal surface above the roof, shielding it from direct solar radiation. After sunset, the photovoltaic modules are flipped vertically upwards to expose the roof to the sky, thus enhancing night-time cooling. Two methods of energy storage are proposed and compared, one using solely battery storage of electrical output, and the other employing a combination of cold water storage and battery storage. The analysis is based on detailed dynamic heat transfer calculations for the entire building envelope, coupled with a solar radiation model, and followed by energy balances. The results reveal that indeed it is feasible to employ solar energy as the only source of energy to power the home, and that each storage system has its own merits and shortcomings. © 2010 WIT Press

Thermal design of a modern, air-conditioned, single-floor, solar-powered desert house

The paper presents a thermal analysis of a single-floor, solar-powered desert house. The house is air-conditioned and provides all modern comforts and facilities. Electrical power, which drives the entire energy system, is generated by roof-mounted photovoltaic modules. The modules are fixed on special cradles which fold at night to expose the roof to the night sky, thereby enhancing night-time cooling, which is substantial in the desert environment. A detailed dynamic heat transfer analysis is conducted for the building envelope, coupled with a solar radiation model. Application to a typical Middle-Eastern desert site reveals that indeed such a design is feasible with present-day technology; and should be even more attractive with future advances in technology. © 2011 Copyright Taylor and Francis Group, LLC

A Conflict Management Model for Architectural Design Collaboration

Until recently the design of a building was carried out only by an architect. The architect maintained enough knowledge of buildings, in addition to knowledge of the social, religious and other aspects of his society, that allowed him to complete a building design. The entire building project was his sole creation.However, the design of buildings today is no longer a one-person operation, because the complexity of a large-scale design and construction exceeds the capacity of any single human's abilities. As we introduce new technologies, materials, and methodologies into building design, we draw on more and more knowledge from disciplines other than architecture and structural engineering. Designing buildings has become an exercise of multi-disciplinary teamwork.Multi-disciplinary collaboration is a complex task. It is especially difficult when design solutions need to be shared and evaluated by participants who represent different professional views of the project. A design solution generated by one participant may satisfy certain requirements and evaluation criteria, but might be contradictory to the goals or values of another participant. The differences signify the domain-expertise each discipline possesses, which is why they were assembled for the purposes of completing the project in the first place. Conflicts among these participants are inevitable, and must be resolved to reach a comprehensive design solution.This dissertation presents a comprehensive approach to negotiation and conflict management in architectural and building design. A primary objective of this research is to define conflict and provide analysis and understanding of its nature. Another objective is to develop a computational model of conflict management and negotiation strategies. To these ends, I developed SWAY a conceptual model that provides a set of conflict resolution algorithms that deal with situations and patterns of a conflict. The model allows designers from various disciplines to avoid conflict if possible and deal with inevitable conflicts in manners that improve the overall quality of the design. The dissertation also aims at enhancing the collaboration process among participants, which result in improving design quality and minimizing delays expenses

Design of a chilled-water storage unit for solar air-conditioning

Solar powered air-conditioning requires some form of thermal energy storage in order to continuously balance energy supply and demand. The current paper is concerned with energy storage in the form of stored chilled water produced by a chiller during times when supply is more than demand. A new multi-tank storage unit design is presented and evaluated employing a specially developed mathematical model and computational code that predicts the various modes of heat transfer occurring within the storage unit. The computational code is both efficient and accurate; it is presented and employed to investigate the effect of various operating parameters and design options on performance. It is revealed that employing only modest insulation, the daily heat penetration is around 2% of the daily stored cooling-capacity. This loss is much lower than the losses involved in other forms of energy storage, such as battery storage, and expected to be cheaper and more environmentally friendly. © 2013 © 2013 Taylor & Francis

Lowering the sink temperature for a desert solar air conditioning system

The paper addresses the problem of cooling air conditioning systems in desert environments where ambient air temperatures are high, and cooling towers should be avoided because of scarcity of water resources. A proposed ground heat-sink is proposed which exploits the highly effective night-time desert cooling by long-wave atmospheric radiation. A simple computer model is presented for the performance of the heat-sink design, which integrates with a load calculation model for a hypothetical zero energy house, in which the air conditioning equipment is solar driven. The load-calculation and thermal-sink models are matched dynamically with the time dependent solar energy characteristics of the selected site, and predicted results are displayed and discussed. © 2011 WIT Press

Modelling the energy systems in a PV powered two floor desert ZEH

The paper presents an integral computational model for the prediction of the thermal performance of a conceptual two-floor, zero energy house (ZEH) in the Arabian desert. The ZEH is powered by PV modules which shade the roof during the day time and retract at night to expose it the sky, thus enhancing night time cooling. The house boasts all modern comforts, including air-conditioning. Solar radiation models coupled with recently published ASHRAE environmental data and models are integrated with a time dependent heat conduction model to predict the heating and cooling loads, for given equipment and storage characteristics. The application of the computational model is demonstrated by employing it to predict the effect of various design parameters on performance and equipment sizing, for a typical desert site in the Kingdom of Saudi Arabia. © 2011 WIT Press