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991.
Abdo Basem M. A. Ahmed Naveed El-Tamimi Abdulaziz M. Anwar Saqib Alkhalefah Hisham Nasr Emad Abouel 《Journal of Mechanical Science and Technology》2019,33(4):1817-1831
Journal of Mechanical Science and Technology - Micro-machining of dental ceramics namely as zirconium oxide is carried out through laser beam machining. Micro-channels of different sizes are... 相似文献
992.
The paper addresses the issue of how residual spaces are intervened upon through formal and informal processes. It argues that a profound understanding for the dynamics of informal interventions, denoted by appropriation, could enhance the performance of their formal peers.Adopting a qualitative approach, the paper departs from Lefebvre’s unitary theory of space and arrives at an analytical framework that helps to understand the appropriation processes in residual spaces. It, then, attempts to empirically challenge the applicability of this framework through analyzing a Cairene residual space that has undergone two cycles of intervention: a formal and informal one. 相似文献
993.
Danish Ansari 《Numerical Heat Transfer, Part A: Applications》2019,75(6):359-380
A hybrid heat sink design with microchannels and stepped pin-fins is introduced for the hotspot-targeted thermal management of microprocessors. The thermal and hydraulic performance were assessed numerically and compared to that of a hybrid heat sink with uniform pin-fins. Both hybrid heat sinks were designed to have two zones using rectangular microchannels above the processor’s background area and an array of pin-fins (stepped and uniform pin-fins) over the hotspot area. Conjugate heat transfer analysis was performed with the entire heat sink as the computational domain by solving the three-dimensional Navier-Stokes and energy equations. The hybrid heat sink with stepped pin-fins exhibited remarkable improvement in the temperature uniformity at the hotspot as compared to the one with uniform pin-fins, along with ample improvements in the thermal resistance, maximum temperature rise at the hotspot, and pumping power. A parametric investigation was also performed for the hybrid heat sink with uniform pin-fins to find an optimum geometry based on two geometric parameters: the ratio of the diameter of the pin-fins to their pitch and the total number of pin-fins in the array. The results revealed improvements in the thermal performance, but the pumping power was increased. 相似文献
994.
The investigation of wind resource at higher heights is very crucial in planning wind power project. Normally, this involves the installation of a high and costly meteorological mast with a cup anemometer and wind vanes. This investigation uses the new ground-based remote-sensing technique Light Detection and Ranging (LiDAR) to investigate the wind resource at higher heights. This paper describes the LiDAR technology principle and examines the potential of LiDAR measurement to estimate the wind resource at higher heights by conducting a measurement campaign at Tamil Nadu, India. The wind statistics were determined using the 10?min average time-series wind data monitored by ZephIR LiDAR. These include the Weibull parameters, daily mean wind speed, wind power density, wind energy density, vertical wind speed profile and capacity factor. The investigation reveals that the vertical wind speed profile measured from the LiDAR system has approximate closer values to the standard meteorological measurement. 相似文献
995.
Ahmed M. Nassef Enas Taha Sayed Cristina Rodriguez A.G. Olabi 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2019,41(17):2094-2103
Biodiesel is one of the promising energy sources that could replace petroleum oil in the near future. Microalgae is occupying a distinguished position among the promising sources for biodiesel production. Enhancement of the lipids production during the pretreatment is a key factor for the biodiesel production. High-pressure homogenizer is a better pretreatment procedure to enhance the lipid extraction from microalgae. In this research, a robust model of biodiesel system using fuzzy logic is built based on the experimental data for biodiesel system. Then, Particle Swarm Optimization (PSO) optimizer is applied for determining the best operating parameters of biodiesel system. The decision variables used in the optimization process are; pressure, number of passes, and reaction time that maximizes the percentage of recovery lipids of biodiesel. A comparison study was carried out between the optimized results thought PSO algorithm and those obtained by the experimental results and the optimized results through the Response Surface Methodology (RMS). Results demonstrated that using the proposed optimization methodology is significantly better than RSM, a nearly 78.7% increase in lipids extraction could be achieved according to the current model. 相似文献
996.
Rizwan Ahmed KHAN Alexandre MEYER Hubert KONIK Saida BOUAKAZ 《Frontiers of Computer Science》2019,13(1):183
This article proposes a novel framework for the recognition of six universal facial expressions. The framework is based on three sets of features extracted from a face image: entropy, brightness, and local binary pattern. First, saliency maps are obtained using the state-of-the-art saliency detection algorithm “frequency-tuned salient region detection”. The idea is to use saliency maps to determine appropriate weights or values for the extracted features (i.e., brightness and entropy).We have performed a visual experiment to validate the performance of the saliency detection algorithm against the human visual system. Eye movements of 15 subjects were recorded using an eye-tracker in free-viewing conditions while they watched a collection of 54 videos selected from the Cohn-Kanade facial expression database. The results of the visual experiment demonstrated that the obtained saliency maps are consistent with the data on human fixations. Finally, the performance of the proposed framework is demonstrated via satisfactory classification results achieved with the Cohn-Kanade database, FG-NET FEED database, and Dartmouth database of children’s faces. 相似文献
997.
998.
Samy M. Shaban Ismail Aiad Fathi A. Yassin Ahmed Mosalam 《Journal of surfactants and detergents》2019,22(6):1445-1460
The surface parameters of some cationic surfactants having different hydrophobic alkyl chains were assessed in aqueous solution using different techniques; surface tension, ultraviolet-Visible (UV–Vis) spectroscopy, and conductivity measurements. The obtained critical micelle concentration (CMC) for N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethyloctan-1-aminium bromide (DBAO), N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethyldodectan-1-aminium bromide (DBAD), and N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethylhexadectan-1-aminium bromide (DBAH) in aqueous solution using three techniques are nearly the same. Increasing the hydrophobic chain length enhances micelle formation. Raising the solution temperature from 25 to 65 °C also shows the same trend. The thermodynamic calculations outlined the adsorption propensity of the surfactants at the surface compared to their affinity to form micelles. Both micellization and adsorption processes are enhanced with both the hydrocarbon elongation and with raising the solution temperature. The effect of the surfactant tail on the preparation process of the silver nanoparticles (AgNP) was assessed and confirmed using transmission electron microscope (TEM), dynamic light scattering (DLS), and UV–Vis spectra. Increasing the surfactant tail leads to a smaller particle size with a narrow distribution. The stability of the prepared AgNP is enhanced with hydrophobic surfactant tail elongation as proved with increasing the zeta-potential of the prepared AgNP colloid. The foaming power, interfacial tension, and emulsification stability of the DBAO, DBAD, and DBAH surfactants were determined. The DBAO, DBAD, and DBAH surfactants showed good antimicrobial activities against both bacteria (Gram positive and negative) and fungi, which have been enhanced because of incorporation of AgNP. 相似文献
999.
Muhammad Ashram Ghassab M. Al-Mazaideh Wael Al-Zereini Ahmed Al-Mustafa Shehadeh Mizyed 《Journal of Sulfur Chemistry》2019,40(3):277-288
A series of new thiacrown ethers derived quinoline 7–9 were synthesized in good yield and in a simple way. Their transition metal ions complexation was studied using a conductometric method in acetonitrile at 25°C. Crowns 7 and 8 showed a continuous decrease in the molar conductances in their complexation with Ag+, Cu2+, Hg2+ and Zn2+ which begins to level off at a molar ratio of 1:1 crown to metal, indicating the formation of 1 stable 1:1 complex. On the other hand, crown 9 showed the formation of 1:1 complexes only with Ag+, Cu2+, Hg2+. The in vitro, a preliminary antimicrobial, antioxidant and cytotoxic effects on breast tumor cells were also reported. Five bacterial test strains were included in the present study. Antioxidant activity was measured in terms of the radical scavenging ability and decolorization of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radicals. Cytotoxic effect of thiacrown was evaluated using MDA MB-231 cell line (human breast adenocarcinoma, ATCC HTB-26). 相似文献
1000.
Ensanya A. Abou Neel Azadeh Kiani Sabeel P. Valappil Nicky M. Mordan Song-Yi Baek Kazi M. Zakir Hossain Reda M. Felfel Ifty Ahmed Kamini Divakarl Wojciech Chrzanowski Jonathan C. Knowles 《应用聚合物科学杂志》2019,136(32):47832
This study aimed to formulate antibacterial dental adhesives. Phosphate-substituted methacrylate adhesives were modified with 0–20 wt % copper-doped glass microparticles. Two shapes of microparticles were used: regular shaped (microspheres) and irregular shaped (microparticles). The morphology/composition, roughness, monomer conversion (DC%), thermogravimetric analysis, and antibacterial action against S. mutans and P. aeruginosa and ion release were investigated. The results showed that microspheres produced adhesives with a relatively smoother surface than microparticles did. The DC% of adhesives increased with increasing glass filler content. Filled adhesives showed polymer decomposition at ~315 °C and glass melting at 600–1000 °C. The weight loss percent of adhesives decreased with increasing weight percent of fillers. Glass microparticles at 0–20 wt % significantly increased the antibacterial action of adhesives against both bacteria. Glass microspheres at 0–5 wt % significantly increased the antibacterial action of adhesives against both bacteria. Only 20 wt % microparticle-filled adhesive showed an inhibition zone similar to tobramycin (positive control). Microparticle-filled adhesives (with >5 wt % filler) significantly reduced S. mutans more than their microsphere counterparts. Microsphere-filled adhesives (with ≤5 wt % filler) significantly reduced P. aeruginosa more than their microparticle counterparts. Microsphere-filled adhesives showed higher Cu release than their microparticle counterparts. Accordingly, phosphate-substituted methacrylate filled with glass could be used as an antibacterial adhesive. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47832. 相似文献