Design of serrate-semi-circular riblets with application to skin friction reduction on engineering surface

Drag reduction in wall-bounded flows can be achieved by the passive flow control technique through the application of bio-inspired riblet surfaces. This paper presents the innovative design of Serrate-Semi-Circular riblet surfaces particularly focusing on the intrinsic relationship between the riblet features and the turbulent boundary layer structure resulting from these surfaces in engineering applications. The available experimental facilities, instrumentation (i.e. hotwire) and measurement techniques (i.e. velocity spectra) have been employed to investigate the boundary layer velocity profiles and skin friction for flat plate and Serrate-Semi-Circular riblet surfaces. Both the simulation and experimental wind tunnel testing results show that the Serrate-Semi-Circular riblet surface can provide 7% drag reduction, which is better than other riblet configurations, such as V and U shaped ones

Modelling the rapid chloride permeability test

A computer model has been written to simulate the Rapid Chloride Permeability Test (RCPT) described in ASTM C1202. The model represents the key processes of diffusion and electromigration using standard equations but then maintains charge neutrality by modelling changes to the voltage distribution. This method enables the model to predict current–time transients similar to those recorded in experiments and it can then be used to obtain basic parameters such as diffusion coefficients for tested samples by optimising to the observed data. Experimental data showing a non-linear voltage distribution is presented together with model results which show that non-linearity has a significant effect on the current. Other predictions from the model are compared with published data and shown to give good agreement

Water vapour and liquid permeability measurements in mortar samples

This paper shows how water permeability may be calculated from measurements of drying under a vacuum. The results obtained are for water vapour transport at low pressures and gas slippage theory is then used to compare them with liquid water permeability measurements on samples of the same mixes. The experimental work includes the drying procedure and also the initial surface absorption test (ISAT), a standard absorption test using a partially immersed sample and a 'through flow' high-pressure test for direct permeability measurements. The results from these tests are compared and additional gas and liquid permeability data from the literature is included for comparison. It is concluded that, with appropriate analysis, all of the procedures give comparable values for intrinsic permeability

Towards Environmental Retrofitting of Egyptian Transitional Spaces: Courtyard-Building in Alexandria University, Egypt

Consuming huge amount of energy and emitting large amount of heat can be assumed as one of the main problems facing urban environment in the world today. These problems associated with current high urban density and less of vegetation within urban fabric. For instance, in Egypt, Universities are today facing rising problem of offering more educational spaces especially in large cities such as Cairo and Alexandria. The study thus focuses on Revival Egyptian buildings in Alexandria University based on hierarchical transitional spaces. As Egyptian transitional spaces, such as courtyards historically were essential outdoor spaces for multiple uses and purposes. As part of retrofitting research project of existed transitional spaces in Alexandria University, this paper focused on one parameter which is building height. This is by targeting to find the maximum height of courtyard building with minimum negative effect on air and thermal flow. This simulation is done with consideration to the surrounding urban context in Alexandria University. The simulation approach is based on two years of field measurement of thermal conditions and air velocity in the Universityrsquos transitional spaces. The study is usingfield-measurement data for nurturing the Computational Fluid Dynamics (CFD) model, and for validating the simulation results. The Computational Fluid Dynamics (CFD) study is done by introducing four cases of different building heights to investigating the changing air and thermal flow inside the existed courtyard. nbs

Gyro-Chirality Effect of Bianisotropic Substrate On the operational of Rectangular Microstrip Patch Antenna

yesIn this paper, the gyrotropic bi-anisotropy of the chiral medium in substrate constitutive parameters (ξc and ηc) of a rectangular microstrip patch antenna is introduced in order to observe its effects on the complex resonant frequency, half-power bandwidth and input impedance. Numerical calculations and analysis based on the dominant mode are carried out to show that the latter is directly related to the former. This paper is based on the Moment Method as full-wave spectral domain approach using sinusoidal basis functions. Two new results, namely the appearance of the difference (ξc-ηc) and sum (ξc+ηc) of the two magneto-electric elements are obtained in the electric transverse components and Green tensor expressions, respectively. These new results can be considered as a generalisation form of the previously published work

Drug-related mutational patterns in hepatitis B virus (HBV) reverse transcriptase proteins from Iranian treatment-Naïve chronic HBV patients

Background: Immunomodulators and Nucleotide analogues have been used globally for the dealing of chronic hepatitis B virus (HBV) infection. However, the development of drug resistance is a major limitation to their long-term effectiveness. Objectives: The aim of this study was to characterize the hepatitis B virus reverse transcriptase (RT) protein variations among Iranian chronic HBV carriers who did not receive any antiviral treatments. Materials and Methods: Hepatitis B virus partial RT genes from 325 chronic in active carrier patients were amplified and directly sequenced. Nucleotide/amino acid substitutions were identified compared to the sequences obtained from the database. Results: All strains belonging to genotype D.365 amino-acid substitutions were found. Mutations related to lamivudine, adefovir, telbivudine, and entecavir occurred in (YMDD) 4% (n = 13), (SVQ) 17.23% (n = 56), (M204I/V + L180M) 2.45% (n = 8) and (M204I) 2.76% (n = 9) of patients, respectively. Conclusions: RT mutants do occur naturally and could be found in HBV carriers who have never received antiviral therapy. However, mutations related to drug resistance in Iranian treatment-naïve chronic HBV patients were found to be higher than other studies published formerly. Chronic HBV patients should be monitored closely prior the commencement of therapy to achieve the best regimen option. © 2013, KOWSAR Corp

Offset Aperture-Coupled Double-Cylinder Dielectric Resonator Antenna with Extended Wideband

YesA compact dielectric resonator antenna for ultra-wideband vehicular communication applications is proposed. Two cylindrical dielectric resonators are asymmetrically located with respect to the center of an offset rectangular coupling aperture, through which they are fed. Optimizing the design parameters results in an impedance bandwidth of 21%, covering the range from 5.9 to 7.32 GHz in the lower-band and a 53% relative bandwidth from 8.72 to 15 GHz in the upper-band. The maximum achieved gain is 12 dBi. Design details of the proposed antenna and the results of both simulations and experiment are presented and discussed

Política de estabilização de renda para a agricultura familiar: uma análise de risco.

Os produtores familiares foram prejudicados pelas políticas de substituição de importações e de modernização da agricultura, sofrendo com elevadas transferências de renda para fora do setor. Uma forma de ressarci-los seria implementando uma política de estabilização de renda que asseguraria rentabilidade estável aos produtores. O objetivo deste artigo é determinar os benefícios de uma política de estabilização de renda implementada na agricultura familiar para agricultores e consumidores de arroz, feijão, milho e mandioca, e os custos para agricultores comerciais nesses mercados. Utilizou-se o modelo de Newbery e Stiglitz, que considera a redução do risco com a política de estabilização de renda. A política implicaria aumento de receita para produtores familiares. Os benefícios de transferência superariam os de eficiência para produtores familiares e consumidores. Os benefícios para a agricultura familiar superariam os custos da agricultura comercial com a política nos mercados de feijão, mandioca e milho, e os benefícios totais superariam os custos totais nos mercados de feijão e milho, ao contrário ocorreria nos mercados de arroz e mandioca, embora neste fosse pequena a diferença. Conclui-se que a implementação da política seria viável nos mercados onde a participação da agricultura familiar fosse maior que a da comercial e naqueles importadores

Re-Thinking "Emotionally": Central of Business District (CBD) of Alexandria City as a Retailing Center

The decisions of the Alexandria Local Authorities would be a key motive power of the flourishing process in Alexandria City Center as a retailing center. The objective of this study is to pay more attention toward re-thinking "Emotionally" to identify any planning policies at various levels. This new tendency would be helpful for having a prosperous city center, after losing its significance as a retailing center. This degradation due to the presence of "Malls and Plazas" like 'City Center Mall," "Green Plaza," and "Down Town Plaza" lying on the peripheral of the city as well as many other reasons. Studying the Saad Zaghloul Street is part of this paper to prove that re-thinking "Emotionally" is the answer to the enhancement Alexandria City Center as a retailing center

Migrant workers' engagement with labour market intermediaries in Europe: symbolic power guiding transnational exchange

This article explores the strategies of migrant workers from post-socialist Central and Eastern Europe (CEE) within the process of transnational exchange characterized by transnational labour market intermediaries that have substantially altered the former national bilateral employment relations. Utilizing a Bourdieuian conceptual framework it examines Slovenian and Polish workers’ migration strategies and struggles to acquire and convert capitals within the process of transnational exchange and upon arrival in the UK. The article uncovers the (self-)colonial cultural capital embodied in CEE workers’ habitus that drives their strategies to take up various working and training opportunities in the UK in order to acquire (trans)nationally recognized cultural capital. This labour of acquisition drives Polish and Slovenian workers to seek specific cross-cultural and ethnic-niche intermediary services that can manipulate the most reliable symbolic signs in order to make profits from migrant worker-consumers. In this regard the article also exposes inter- and intra-ethnic variations