10,551 research outputs found

    Command system study for the operation and control of unmanned scientific satellites, task III - Command system interference Third quarterly progress report, 1 Jan. - 31 Mar. 1965

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    Effects of CW and modulated interference on baseband of AM and FM demodulators used for control of unmanned scientific satellite

    NOViSE: a virtual natural orifice transluminal endoscopic surgery simulator

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    Purpose: Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a novel technique in minimally invasive surgery whereby a flexible endoscope is inserted via a natural orifice to gain access to the abdominal cavity, leaving no external scars. This innovative use of flexible endoscopy creates many new challenges and is associated with a steep learning curve for clinicians. Methods: We developed NOViSE - the first force-feedback enabled virtual reality simulator for NOTES training supporting a flexible endoscope. The haptic device is custom built and the behaviour of the virtual flexible endoscope is based on an established theoretical framework – the Cosserat Theory of Elastic Rods. Results: We present the application of NOViSE to the simulation of a hybrid trans-gastric cholecystectomy procedure. Preliminary results of face, content and construct validation have previously shown that NOViSE delivers the required level of realism for training of endoscopic manipulation skills specific to NOTES Conclusions: VR simulation of NOTES procedures can contribute to surgical training and improve the educational experience without putting patients at risk, raising ethical issues or requiring expensive animal or cadaver facilities. In the context of an experimental technique, NOViSE could potentially facilitate NOTES development and contribute to its wider use by keeping practitioners up to date with this novel surgical technique. NOViSE is a first prototype and the initial results indicate that it provides promising foundations for further development

    Ionic behavior assessment of surface-active compounds from corn steep liquor by exchange resins

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    Depending on their ionic nature, biosurfactants can be classified as nonionic, anionic, cationic, or amphoteric. The ionic behavior of biosurfactants is an important characteristic that dictates their use in industrial applications. In this work, a biosurfactant extract obtained from corn steep liquor was subjected to anionic or cationic resins, in order to study the ionic behavior under different operational conditions using response surface methodology. The independent variables included in the study are the dilution of biosurfactant solution, the amount of cationic or anionic resin, and the extraction time, whereas the dependent variables studied consisted of the surface tension of biosurfactant aqueous solution, after contacting with anionic or cationic resin. The results showed that biosurfactant extracted from corn steep liquor is amphoteric, since both resins were able to entrap this biosurfactant, making it particularly suited for use in personal care preparations for sensitive skin.Peer ReviewedPostprint (author's final draft

    Observations of solar small-scale magnetic flux-sheet emergence

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    Aims. Moreno-Insertis et al. (2018) recently discovered two types of flux emergence in their numerical simulations: magnetic loops and magnetic sheet emergence. Whereas magnetic loop emergence has been documented well in the last years, by utilising high-resolution full Stokes data from ground-based telescopes as well as satellites, magnetic sheet emergence is still an understudied process. We report here on the first clear observational evidence of a magnetic sheet emergence and characterise its development. Methods. Full Stokes spectra from the Hinode spectropolarimeter were inverted with the SIR code to obtain solar atmospheric parameters such as temperature, line-of-sight velocities and full magnetic field vector information. Results. We analyse a magnetic flux emergence event observed in the quiet-sun internetwork. After a large scale appearance of linear polarisation, a magnetic sheet with horizontal magnetic flux density of up to 194 Mx/cm2^{2} hovers in the low photosphere spanning a region of 2 to 3 arcsec. The magnetic field azimuth obtained through Stokes inversions clearly shows an organised structure of transversal magnetic flux density emerging. The granule below the magnetic flux-sheet tears the structure apart leaving the emerged flux to form several magnetic loops at the edges of the granule. Conclusions. A large amount of flux with strong horizontal magnetic fields surfaces through the interplay of buried magnetic flux and convective motions. The magnetic flux emerges within 10 minutes and we find a longitudinal magnetic flux at the foot points of the order of \sim101810^{18} Mx. This is one to two orders of magnitude larger than what has been reported for small-scale magnetic loops. The convective flows feed the newly emerged flux into the pre-existing magnetic population on a granular scale.Comment: 6 pages, 5 figures, accepted as a letter in A&

    Redescription of Aorolaimus capsici Jiménez Millan, Arias & Fijo, 1964 (Nematoda : Tylenchida)

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    La redescription d'#Aorolaimus capsici Jiménez Millan, Arias & Fijo, 1964 et une étude comparative du matériel type de cette espèce et de trois populations d'#A. perscitus (Doucet, 1980) Fortuner, 1987 ont été réalisées. Les faibles différences morphométriques montrées par les populations étudiées ne justifiant pas l'existence de deux espèces, il est proposé de considérer #A. persicus comme un synonyme mineur d'#A. capsici. (Résumé d'auteur

    HCME: An Environment-Friendly I.C. Engine Fuel

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    The study revealed that Hura crepitans oil is a good candidate for Hura crepitans methyl ester (HCME) production. Two steps (esterification and transesterification) production stages influenced the high yield of HCME. Three possible experimental runs were performed in each step, the best of the three conditions were 1.45 (% v/v) for H2SO4 conc., 5:1 for methanol/oil molar ratio, 40 min for reaction time which gave 1.06 % for FFA in the first step, in the second step, 92.70 %(w/w) of HCME was obtained at 0.55% KOH, 5:1 methanol/oil molar ratio, 60 oC temperature and 30 min reaction time. The produced HCME had fuel properties which satisfied both ASTME D6751 and EN 1424 standards. The fatty acid profile of the HCME revealed the dominant fatty acids were linoleic (64.50%), oleic (17.54%) and palmitic (12.70%). Exhaust emissions from an internal combustion (I.C.) engine revealed that there is 60% decreased in CO, 58% decreased in NOx, 60% decreased in HC, 39% decrease in smoke opacity and 42% decreased in BSFC at B20, respectively. Flue gas temperature increased by 12% at B20, 45% increased in BTE at B50 when compared to pure diesel (AGO). Hence, it can be concluded that B20 (20% HCME + 80% AGO) will provides the best emission reduction at the lowest cost

    Prediction of Natural Gas Compressibility Factor in a Single-Phase Gas Reservoir: A Comparative Study

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    Natural gas compressibility factor plays important roles in pipeline design, reserve estimation and gas metering. The aim of this study is to presents the most accurate and reliable method of computing gas compressibility factor in a single-phase gas reservoir at various reservoir pressures. In this study, the gas compositions and the specific gravity of the respective gas compounds were retrieved from literatures. This specific gravity determine the pseudo critical and the pseudo reduced properties (temperature and pressure) of the respective gas compounds being studied. The predicted methods studied are Papay correlation, Hall-Yarborough equation of state (EOS), viral EOS, Beggs and Brill and Dranchuk-Abu-Kassem correlation. The methods are expressed as functions of the pseudo-reduced temperature and pressure, thereby predicting the compressibility factor of the predicted methods. The accuracy and the performance of the methods were tested by comparing the results obtained from the methods studied with experimental z-factor values obtained from the literatures. The experimental z-factor values were set as standard for the predicted methods studied. Six (6) statistical parameters and various charts (line and column charts) were used to attest the effectiveness and the precision of the methods. The statistical tools are average absolute error (AAE), average absolute relative error (AARE), root mean square error (RMSE), residual sum of square (RSS), mean square error (MSE) and coefficient of determination (R2). The results of the study shows that, the Papay correlation has the highest coefficient of regression, R2= 92%, rated as the most accurate, reliable and best method. The Hall-Yarborough equation of state has R2 of 86%. The Viral equation of state has R2 of 83%. The Beggs and Brill correlation has R2 of 42%. The Dranchuk-Abu-Kassem correlation has R2 of 10.5%. The Beggs and Brills correlation method is not suitable for application, if the pseudo-reduced pressure is less than 0.92. The Dranchuk-Abu-Kassem correlation is only applicable, if the pseudo-reduced properties are within the range of 0.2<Ppr<15, 1.0<Tpr<3.0. The Hall-Yarborough equation of state cannot be used if the pseudo-reduced temperature is less than one

    An Examination of the Effectiveness of Economic Recovery and Growth Plan in Nigeria

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    Right from the independence and especially since the return to democratic governance in 1999, the successive governments in Nigeria have made concerted efforts in economic and development planning. Nigeria’s quest for a sustainable development roadmap has been a torturous one since independence with various plans and policies developed to fast-track the economy. However, no meaningful change has been witnessed thus making all successive governments come up with different development blueprints on how to rejig the economy. The Buhari Administration has come up with the Economic Recovery and Growth Plan (ERGP), a Medium-Term Plan for 2017-2020 which was built on the Strategic Implementation Plan (SIP) to restore economic growth while leveraging the ingenuity and resilience of the Nigerian people. It is sufficient to say that the Economic Recovery and Growth Plan (ERGP) was a medium-term, all-around developmental initiative that focused on restoring growth, investing in people, and building a globally competitive economy. The main objective of this paper is to examine the performance of the plan as a developmental state paradigm for “Nigeria's economic recovery”. Data were generated from secondary sources. The study revealed that, even though ERGP was implemented properly, its expected positive impact on GDP growth, reduction of inflation, and unemployment is not satisfactory. Accordingly, restructuring of the economy through diversification needs to be seriously sustained in Nigeria. Keywords: Economic Recovery and Growth Plan (ERGP), Nigerian Populace, Strategic Implementation Plan, Nigerian Economy, Development Plannin

    Prioritising socio-economic rights in sovereign debt governance: The obligations of private creditors

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    Over the past few decades, sovereign debt crises have become recurring phenomena across the world. Studies have shown the devastating impacts of these crises on the realisation of socio-economic rights. Sovereign debtors constantly face an “obligatory dilemma” of simultaneously satisfying multiple contractual and treaty obligations owed to different constituencies, including to their citizens and private creditors. Unfortunately, there is currently no binding legal framework to deal with sovereign debt crises and, consequently, creditors are unwilling to compromise. Therefore, using Waldron’s theory of socio-economic rights, this article argues for the prioritisation of socio-economic rights considerations during debt crises. It observes a convergence between the areas of business and human rights and sovereign debt restructuring regimes and suggests the employment of the former to achieve this prioritisation. This can be done by taking advantage of the efforts to develop a binding instrument on business and human rights
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