19672 research outputs found
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Magnetic resonance coupling for 5G WPT applications
No full textInductive Wireless Power Transfer (IWPT) is the most popular and common technology for the resonance coupling power transfer. However, in 2007 it has experimentally demonstrated by a research group from Massachusets Institute of Technology (MIT) that WPT can be improved by using Magnetic Resonance Coupling Wireless Power Transfer (MRC WPT) in terms of the coupling distance and efficiency. Furthermore, by exploiting the unused, high-frequency mm-wave band which are ranging from 3~300 GHz frequency band, the next 5G generations of wireless networks will be able to support a higher number of devices with the increasing data rate, higher energy efficiency and also compatible with the previous technology. In this work, a square planar inductor with the dimension of 6.1 × 6.1 mm is designed, and the resonators have the same self-resonance frequency at 14 GHz. The coil resonators have been laid on Silicon and Oxide substrate to reduce the loss in the design. From the CST software simulation and the analytical model in MATLAB software, it has been shown that the MRC WPT design has improved the performance of IWPT design by 40% power transfer efficiency. MRC WPT design also has larger H-Field value which is 705.5 A/m, as compared to the IWPT design which has only 285.6 A/m when both Transmitter(Tx) and Reciever(RX) is at 0.3 mm coupling distance. © 2019 Institute of Advanced Engineering and Science. All rights reserved
Three phase grid connected neutral point clamped (NPC) multilevel inverter fed by two wind turbines
No full textThis paper presents two gear driven wind turbine generators (WTG) feeding a single three level grid connected NPC inverter. Each component of WTG is made up of wind turbine, 2-mass gear drive, permanent magnet synchronous generator (PMSG), AC-DC-AC power converter. A simple advanced hill climbs search (AHCS) maximum power point tracking algorithm that uses the mechanical power from the Wind turbine was developed to generate proper duty cycle for the control of single stage DC/DC boost converter. The DC link voltages are series interconnected and fed to a sinusoidal pulse width modulation (SPWM) controlled high power inverter. The complete model is simulated using MATLAB/ SIMULINK software under fixed and fluctuating wind speed conditions. Simulation results have shown that WECs exhibit variability in their output power as a result of changes in their prime movers (wind speed). © 2019, Universiti Putra Malaysia Press. All rights reserved
An evaluation of teachers opinions about the servant leadership behaviours of school principals: A critical review
No full textThis is a review of 'An Evaluation of Teachers' Opinions about the Servant Leadership Behaviours of School Principals' published in Educational Process: International Journal. That article delves into how school teachers perceive the implementation of the 'Servant Leadership Behaviours' concept by school principals, where teachers serve under these principals' supervision. It also identifies the level of this concept's application in primary and secondary schools. The article has strengths and weaknesses. The concept of servant leadership by school principals is well-explained and it effectively employs methodology (snowball sampling and content analysis). It systematises data, succeeds in answering the research questions, and its references are compatible with bibliographic rules. But the article lacks a research problem statement or review of past studies, has a shallow and unorganised introduction, and only vaguely distinguishes data analysis from its overall conclusion. Finally, the current review identifies the article's positives for readers despite its few weaknesses.. © 2019 Primrose Hall Publishing Group
Ruthenium oxide/tungsten oxide composite nanofibers as anode catalysts for the green energy generation of Chlorella vulgaris mediated biophotovoltaic cells
No full textThe development of electrochemically active and stable anode catalysts for the photoelectrochemical splitting of water molecules via biophotovoltaic cells (BPVs) utilizing microalgae receives a prime importance in green energy sector. Herein, we report the ruthenium oxide (RuO2)/tungsten oxide (WO3) composite nanofibers based photoanode for the application of high performance and durable BPV. The sequential arrangement of 6 nm sized RuO2/WO3 spherical particles constitutes the nanofibrous morphology and a number of surface active sites and structural integrity of nanofibers demonstrate the excellent and stable photo-oxidation currents. Under the light regime, RuO2/WO3/carbon cloth photoanode exhibits the substantial BPV power and current densities with an excellent durability. Thus this systematic study evokes the fundamental understanding on the electron generation and transference mechanisms, which offers new dimensions in the development of high performance and durable BPVs. © 2019 American Institute of Chemical Engineer
Materials Effect in Sensing Performance Based on Surface Plasmon Resonance Using Photonic Crystal Fiber
No full textThis article explores the effect of sensing performances with subject to change in different types of material and this study is carried out by the support of plasmon-coated photonic crystal fiber (PCF). Three different materials gold, niobium, and doping materials (niobium and Al2O3) have been used as sensing materials to find out the best performance of the raised structure. Each material deposited sequentially on the PCF surface and the structural characterization is analyzed by finite element method (FEM).The investigation shows that it can provide the enhanced wavelength sensitivity of 5000 nm/RIU, 8000 nm/RIU, and 10,000 nm/RIU; and amplitude sensitivity of 171 RIU−1, 188 RIU−1, and 249 RIU−1 for gold, niobium, and doping materials, respectively, at analytes 1.37 and 1.38. In both cases, doping materials show best outcome. Moreover, the proposed model is also investigated to detect the change of phase matching point with the variation of center air hole diameter. The obtained results ensure that it may be helpful for any chemical or biological analytes detection. © 2018, Springer Science+Business Media, LLC, part of Springer Nature
4-Imidazol-1-yl-butane-1-sulfonic acid ionic liquid: Synthesis, structural analysis, physical properties and catalytic application as dual solvent-catalyst
No full text4-Imidazol-1-yl-butane-1-sulfonic acid (ImBu-SO3H) has been successfully synthetized and fully characterized by FT-IR and high-resolution NMR spectroscopy (1H, 13C). The “plausible” alternative structures of ImBu-SO3H were discussed on the basis of its NMR data. The ionic liquid showed interesting dual solvent-catalyst property, which was studied experimentally for the acetylation of a variety of functionalized alcohols, phenols, thiols, amines and α-tocopherol (α-CTP) as the most active form of vitamin E with acetic anhydride and which provided good yields within a short reaction time. ImBu-SO3H was successfully recycled by product extraction with an average recovered yield of 82% for 5 subsequent runs. The catalytic activity of the recycled ImBu-SO3H showed almost no loss even after five consecutive runs. © 2019, © 2019 Taylor & Francis Group, LLC
Determining the Accuracy of the Mandibular Canal Region in 3D Biomodels Fabricated from CBCT Scanned Data: A Cadaveric Study
No full textObjective: To validate the accuracy of the mandibular canal region in 3D biomodel produced by using data obtained from Cone-Beam Computed Tomography (CBCT) of cadaveric mandibles. Methods: Six hemi-mandible samples were scanned using the i-CAT CBCT system. The scanned data was transferred to the OsiriX software for measurement protocol and subsequently into Mimics software to fabricate customized cutting jigs and 3D biomodels based on rapid prototyping technology. The hemi-mandibles were segmented into 5 dentoalveolar blocks using the customized jigs. Digital calliper was used to measure six distances surrounding the mandibular canal on each section. The same distances were measured on the corresponding cross-sectional OsiriX images and the 3D biomodels of each dentoalveolar block. Results: Statistically no significant difference was found when measurements from OsiriX images and 3D biomodels were compared to the “gold standard” -direct digital calliper measurement of the cadaveric dentoalveolar blocks. Moreover, the mean value difference of the various measurements between the different study components was also minimal. Conclusion: Various distances surrounding the mandibular canal from 3D biomodels produced from the CBCT scanned data was similar to that of direct digital calliper measurements of the cadaveric specimens. © 2019 Bentham Science Publishers
Assessment of Eocene, Paleocene and Cretaceous source rocks in the West Feiran area, offshore Gulf of Suez, Egypt
No full textThe study area is located in the West Feiran area, offshore Gulf of Suez, Egypt. This gulf is a well-known petroleum prolific basin that was formed from Late-Oligocene to Early Miocene times. This study focuses on evaluating the source rocks of Eocene (Thebes Formation), Paleocene (Esna Formation) and Cretaceous (Sudr, Brown Ls., Matulla, Wata and Raha formations) of GS 197–2 and WFA-1 wells based on total organic carbon (TOC), Rock-Eval pyrolysis, vitrinite reflectance (VR), and seismic data. In this study, Thebes, Sudr and Brown Ls. are considered to have fair to very good TOC (up to 4.05 wt%) that are characterized by Type II kerogen (mainly oil-prone) and mixed Type II/III kerogen (swamp oil and gas-prone), but haven't reach the peak of hydrocarbon generation at present depth of GS 197–2 well. On the other hand, Esna, Matulla, Wata and Raha formations have relatively lower TOC (only up to 1.15 wt%). For these formations the quality of the organic matter is represented by mixed Type II/III and Type III kerogen (mainly gas-prone), but have reached the maturation and generation stages in both wells with the presence of indigenous hydrocarbons detected. Depth-structure maps of these source rocks based on seismic data interpretation indicate that the mature source rocks located in the NW direction are so much deeper than the others in the study area. Understanding regional variations of Eocene, Paleocene and Cretaceous source-rock maturities which largely depend on burial depth will help to reduce the risk for future exploration drilling within the Gulf of Suez. © 2019 Elsevier B.V
Synthesis, characterization, and evaluation of silver(I) complexes with mixed-ligands of thiosemicarbazones and diphenyl(p-tolyl)phosphine as biological agents
No full textFive new silver(I) complexes were synthesized with mixed ligands of thiosemicarbazone derivatives and diphenyl(p-tolyl)phosphine in search of new biologically active compounds. A CHN elemental analysis, powder X-ray diffraction (PXRD) data and several spectroscopic techniques such as Fourier-transform infrared spectroscopy, energy-dispersive X-ray, 1 H, 13 C, and 31 P{ 1 H} NMR were performed to elucidate the structure of these complexes. Elemental analysis suggested that the stoichiometry of the complexes formed by the reaction of silver nitrate with thiosemicarbazone in the presence of (p-tolyl)PPh 2 was indeed 1:2:1 molar ratio. The silver ions were discovered to be coordinated to the sulfur of thiosemicarbazone and phosphorus of (p-tolyl)PPh 2 , having a tetrahedral geometry based on the spectroscopic data obtained. The PXRD patterns were studied to see the degree of crystallinity of the complexes. The in vitro antiproliferative activity of these complexes was investigated toward the MDA-MB-231 and MCF-7 breast cancer cell lines, as well as the HT-29 colon cancer cell line, which yielded IC 50 values in low micromolar range. The antiplasmodial activity of these complexes was also examined against chloroquine-resistant Plasmodium falciparum parasite which demonstrated good activity and further tested for their selectivity index. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group
Uniformity improvement by integrated electrochemical-plating process for CMOS logic technologies
No full textReliability of metal interconnects and the integration of inspection and metrology with process tools are advancing rapidly to overcome obstacles in down stream production. A significant drawback associated with metal interconnects which has resulted from the recent trend is the difficulty in obtaining uniform electroplated layer thicknesses across the maximum lateral dimension of the CMOS logic wafer. The prime objective of this paper is, to-root-cause uniformity troubleshooting by the adoption of integrated diffuser in electrochemical-plating (ECP) system optimizations. These are to quantify the best degree of uniformity and high resistivity to enhance an even current distribution on the wafer. The results show that uniformity of the deposited film has been improved significantly with 1.9%. i.e., maximum deviation of the deposited film thickness is at about 1.9% of the average film thickness, while standard electroplating processes typically achieves uniformity at best within 5.5%. Furthermore, the origin of “hot spots’’ that caused poor uniformity was identified and greatly overcome with the improved ECP system comprising an integrated diffuser design and process modifications in real troubleshooting of back –end operation line (BEOL) of semiconductor foundry. © 2019 The Society of Manufacturing Engineer