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Optimisation of a novel trailing edge concept for a high lift device
Botha, Jason D.M.,Dala, Laurent,Schaber, S. Techno-Press 2015 Advances in aircraft and spacecraft science Vol.2 No.3
This study aimed to observe the effect of a novel concept (referred to as the flap extension) implemented on the leading edge of the flap of a three element high lift device. The high lift device, consisting of a flap, main element and slat is designed around an Airbus research profile for sufficient take off and landing performance of a large commercial aircraft. The concept is realised on the profile and numerically optimised to achieve an optimum geometry. Two different optimisation approaches based on Genetic Algorithm optimisations are used: a zero order approach which makes simplifying assumptions to achieve an optimised solution: as well as a direct approach which employs an optimisation in ANSYS DesignXplorer using RANS calculations. Both methods converge to different optimised solutions due to simplifying assumptions. The solution to the zero order optimisation showed a decreased stall angle and decreased maximum lift coefficient against angle of attack due to early stall onset at the flap. The DesignXplorer optimised solution matched that of the baseline solution very closely. The concept was seen to increase lift locally at the flap for both optimisation methods.
The Optical and Electrical Properties of AP-MOVPE GaSb Grown Using TEGa and TMSb
S. S. Miya,V. Wagener,J. R. Botha 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2
High quality undoped metal-organic vapour phase epitaxial (MOVPE) GaSb layers have been grown on GaAs using the trimethylantimony/triethylgallium (TMSb/TEGa) precursor combination at 550°C and atmospheric pressure. The effects of the TMSb to TEGa flux ratio (i.e. V/III ratio) on the surface morphology and optical and transport properties of these layers have been investigated. The transport properties were found to be comparable to the best reported for un-doped GaSb grown using the same precursors at low reactor pressures. Two models (using either two monovalent acceptors or one divalent acceptor) were used to estimate the density of native acceptors and the ionization energy of the acceptors in GaSb. These models showed the shallow acceptor activation energy or first ionization energy to be ~30 meV (falling within the reported range of 20 - 40 meV). The ionization energy of the deeper acceptor or second ionization of the level was determined to be ~120 meV.
Sebastian S Zeki,Ismail Miah,Pierfrancesco Visaggi,Anna Wolak,Minerva deSilva,Jason M Dunn,Andrew Davies,James Gossage,Abrie Botha,Guiping Sui,Jafar Jafari,Terry Wong 대한소화기 기능성질환∙운동학회 2023 Journal of Neurogastroenterology and Motility (JNM Vol.29 No.3
Background/AimsExtended wireless pH monitoring (WPM) is used to investigate gastroesophageal reflux disease (GERD) as subsequent or alternative investigation to 24-hour catheter-based studies. However, false negative catheter studies may occur in patients with intermittent reflux or due to catheter-induced discomfort or altered behavior. We aim to investigate the diagnostic yield of WPM after a negative 24-hour multichannel intraluminal impedance pH (MII-pH) monitoring study and to determine predictors of GERD on WPM given a negative MII-pH. MethodsConsecutive adult patients (> 18 years) who underwent WPM for further investigation of suspected GERD following a negative 24-hour MII-pH and upper endoscopy between January 2010 and December 2019 were retrospectively included. Clinical data, endoscopy, MII-pH, and WPM results were retrieved. Fisher’s exact test, Wilcoxon rank sum test, or Student’s t test were used to compare data. Logistic regression analysis was used to investigate predictors of positive WMP. ResultsOne hundred and eighty-one consecutive patients underwent WPM following a negative MII-pH study. On average and worst day analysis, 33.7% (61/181) and 34.2% (62/181) of the patients negative for GERD on MII-pH were given a diagnosis of GERD following WPM, respectively. On a stepwise multiple logistic regression analysis, the basal respiratory minimum pressure of the lower esophageal sphincter was a significant predictor of GERD with OR = 0.95 (0.90-1.00, P = 0.041). ConclusionsWPM increases GERD diagnostic yield in patients with a negative MII-pH selected for further testing based on clinical suspicion. Further studies are needed to assess the role of WPM as a first line investigation in patients with GERD symptoms.
Surface modification of bulk n-InAs (111)A etched in bromineemethanol
N. Eassa,R. Betz,E. Coetsee,H.C. Swart,A. Venter,J. R. Botha 한국물리학회 2013 Current Applied Physics Vol.13 No.2
X-ray photoelectron spectroscopy, field emission scanning electron microscopy, Raman and photoluminescence spectroscopy were used to evaluate the surface properties of n-type InAs (111)A etched in a 1% Bremethanol solution. Etching completely removes the native oxides from the surface and enhances the photoluminescence response. The adsorption of bromine onto the InAs surface leads to the formation of IneBrx and AseBrx bonds (x ¼ 1, 2, 3) as inferred from changes in the In 3d3/2;5/2 and As 3d core level binding energies. The etch rate is found to decrease due to strong anisotropic effects and the high volatility of the bromine species. A 1 min Bremethanol etch was found to enhance the photoluminescence intensity by a factor of 3, probably due to a reduction in the surface state density upon deoxidation of the surface. This is thought to be due to reductions in the surface state density. The presence of native oxides enhances both the surface accumulation layer and the surface state density.
Final report on international key comparison APMP.QM-K41: 10 µmol/mol hydrogen sulfide in nitrogen
Kim, Yong-Doo,Heo, Gwi-Suk,Lee, Sangil,Han, Qiao,Wu, Hai,Konopelko, Leonid A,Kustikov, Yury A,Malginov, Andrey V,Gromova, Elena V,Pankratov, Vladimir V,Pavlov, Mikhai V,Botha, Angelique Springer-Verlag 2014 METROLOGIA -BERLIN- Vol.51 No.-
<P>This report presents the results of APMP.QM-K41, a key comparison. This comparison is designed to test the capabilities of the NMIs to measure and certify hydrogen sulfide at a nominal amount fraction of 10 µmol/mol in nitrogen. This comparison provides an opportunity to the NMIs in APMP to submit supporting evidence for CMC at the same level as CCQM-K41. The results from this comparison are linked with CCQM-K41.</P><P>Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.</P><P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>