1,258 research outputs found
Analysis of medium-speed runway exit manoeuvres
No full textRecent studies suggest that fuel savings can be realised if more efficient surface movements can be achieved through means other than the engines of an aircraft, or by optimising the scheduling of aircraft on the ground. All aspects of ground manoeuvring therefore need to be studied to understand the impact of such changes. This paper presents an analysis method for medium-speed manoeuvres, and, more specifically, runway exit manoeuvres. Kinematic equations that were derived for towing analysis form the basis of the runway exit study, from which empirical formulas are derived for steering angle and clearance predictions. The results of the empirical method compare very well with kinematic studies, as well as detailed dynamic model simulations, as is demonstrated with the test case example of an A380 model. The empirical formulas can be used to great effect during the early design phases of an aircraft programme for the prediction of steering angles and clearance distances, when very little data is available. The greatest advantage of the proposed method is that any aircraft configuration or runway exit can be analysed
Application of bifurcation methods for the prediction of low-speed aircraft ground performance
No full textThe design of aircraft for ground manoeuvres is an essential part in satisfying the demanding requirements of the aircraft operators. Extensive analysis is done to ensure that a new civil aircraft type will adhere to these requirements, where the nonlinear nature of the problem generally adds to the complexity of such calculations. Small perturbations in velocity, steering angle or brake application may lead to significant differences in the final turn-widths that can be achieved. Here, the U-turn manoeuvre is analysed in detail, with a comparison between the two ways in which this manoeuvre is conducted. A comparison is also made between existing turn-width prediction methods that consist mainly of geometric methods and simulations, and a proposed new method that uses dynamical systems theory. Some assumptions are made with regards to the transient behaviour, where it is shown that these assumptions are conservative when an upper bound is chosen for the transient distance. Furthermore, we demonstrate that the results from the dynamical systems analysis are sufficiently close to the results from simulations to be used as a valuable design tool. Overall, dynamical systems methods provide an order of magnitude increase in analysis speed and capability for the prediction of turn-widths on the ground, compared to simulations
AUTHOR CONTRIBUTION
No full textConception or design of the study: Silva AC, Silva LG, Souza ARS, Martins, AKL, Gomes EB. Data collection: Silva AC, Silva LG, Souza ARS. Analysis and interpretation of the data: Silva AC, Silva LG, Souza ARS. Writing of the article or critical review: Silva AC, Gomes EB. Final approval of the version to be published: Silva AC, Martins, AKL, Oliveira CJ, Alencar AMPG, Gomes EB
Supporting safe motherhood : a review of financial trends : summary
No full textAn estimated 500,000 women, 99 percent of them from the developing world, die each year from pregnancy-related causes. About three quarters of these deaths are the direct result of obstetrical complications -- hemorrhage, infection, toxemia, obstructed labor, and abortion (under primitive and illegal conditions). An estimated equivalent number of infants do not survive their mother's death. For surviving mothers, the consequences of pregnancy have a severe impact on health and family economics. The strategy for safe motherhood is based on two approaches. First, the encouragement of activities that indirectly improve maternal health. These include education, policies to improve women's rights and working conditions, health care and nutrition, transportation and communication systems, water and sanitation facilities, and increases in family income and food production. The second approach targets activities to reduce maternal deaths. These activities include reducing unwanted pregnancies through the provision of family planning services, and through national policies that recognize the importance of this issue. A second objective is to reduce the risks of pregnancy through providing community-based family planning and prenatal services to identify high-risk cases'adequate referral services for the complications of pregnancy, and communication and transport systems to support patient referral procedures.Health Monitoring&Evaluation,Health Systems Development&Reform,Gender and Health,Early Child and Children's Health,Agricultural Knowledge&Information Systems
AUTHOR CONTRIBUTION
No full textConception or design of the study: Silva AC, Silva LG, Souza ARS, Martins, AKL, Gomes EB. Data collection: Silva AC, Silva LG, Souza ARS. Analysis and interpretation of the data: Silva AC, Silva LG, Souza ARS. Writing of the article or critical review: Silva AC, Gomes EB. Final approval of the version to be published: Silva AC, Martins, AKL, Oliveira CJ, Alencar AMPG, Gomes EB
AUTHOR CONTRIBUTION
No full textConception or design of the study: Silva AC, Silva LG, Souza ARS, Martins, AKL, Gomes EB. Data collection: Silva AC, Silva LG, Souza ARS. Analysis and interpretation of the data: Silva AC, Silva LG, Souza ARS. Writing of the article or critical review: Silva AC, Gomes EB. Final approval of the version to be published: Silva AC, Martins, AKL, Oliveira CJ, Alencar AMPG, Gomes EB
EB-KG: Knowledge Graph of the first 8 eiditions Encyclopaedia Brittanica (1768-1860)
No full textThis Knowlege Graph represents the information of the first eight editions of Encyclopaedia Brittanica (years: 1768 to 1860) in RDF (ttl format).
The raw dataset is provided by the NLS in this link , and it comprises of eight editions and a total of 195 volumes with a total size of 44GB. It uses two XMLs schemas: METS for descriptive, structural, technical and administrative metadata (Title, Author, Publisher, etc); and ALTO for encoding the OCR text of a page.
In this work, we have extracted the information from METS and ALTO XMLS using defoe tool and developed novel information extraction heuristics. With the extracted information, we created the EB-KG Knowlege Graph, which uses the EB Ontolgy, to represent such information. Furthermore, during the information extraction phase, we have employed several techniques to mitigate two common OCR errors: long-S and the line-break hyphenation.
The EB-KG contains 1,638,239 RDF triples. It has information from 8 editions. Each edition can have several Volumes, references to Books, Supplements; it also has an Editor and a Publisher, which can be a Person or an Organization. A Volume has several Pages, which can contain several Terms. And a Term can be either a Topic (a term described across several pages, often combining text, pictures, and tables.) or an Article (a description of the term in one- or two-paragraph long text (similar to an entry in a dictionary)). The data model of the EB-KG can be found here.
The original ALTO files do not indicate the start and end of each EB term, the first part of our work involved the
automated extraction of all terms (along with their metadata) across editions, so they can be analysed independently without the surrounding text.This work was performed during my 2021-2022 National Library of Scotland Digital Scholarship Fellowship
Effect of build location on microstructural characteristics and corrosion behavior of EB-PBF built Alloy 718
No full textElectron beam-powder bed fusion (EB-PBF), a high-temperature additive manufacturing (AM) technique, shows great promise in the production of high-quality metallic parts in different applications such as the aerospace industry. To achieve a higher build efficiency, it is ideal to build multiple parts together with as low spacing as possible between the respective parts. In the EB-PBF technique, there are many unknown variations in microstructural characteristics and functional performance that could be induced as a result of the location of the parts on the build plate, gaps between the parts and part geometry, etc. In the present study, the variations in the microstructure and corrosion performance as a function of the parts location on the build plate in the EB-PBF process were investigated. The microstructural features were correlated with the thermal history of the samples built in different locations on the build plate, including exterior (the outermost), middle (between the outermost and innermost), and interior (the innermost) regions. The cubic coupons located in the exterior regions showed increased level (~ 20 %) of defects (mainly in the form of shrinkage pores) and lower level (~ 30-35 %) of Nb-rich phase fraction due to their higher cooling rates compared to the interior and middle samples. Electrochemical investigations showed that the location indirectly had a substantial influence on the corrosion behavior, verified by a significant increase in polarization resistance (Rp) from the exterior (2.1 ± 0.3 kΩ.cm2) to interior regions (39.2 ± 4.1 kΩ.cm2). © 2020, The Author(s)
Comparison of culture methodology for the detection of methicillin-resistant Staphylococcus pseudintermedius in clinical specimens collected from dogs
No full textMethicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged as a major pathogen in dogs and has been implicated as a hospital-acquired pathogen in veterinary hospitals. We attempted to determine if selective culture methods will detect more MRSP when compared to the traditional culture methods in clinical samples from dogs in Atlantic Canada with a high risk for MRSP infection. Each sample was tested using 4 culture methods: traditional culture; mannitol salt agar with 2 μg/mL of oxacillin (MSAox); enrichment broth (EB) with MSAox; and EB with traditional culture. Detection of penicillin-binding protein 2', via latex agglutination, was used as a confirmatory test for oxacillin resistance. We analyzed 741 samples from 556 dogs between February 2013 and April 2014. The prevalence of MRSP in samples detected by any method was estimated at 13.4% (95% CI: 11.1-16.0%). When the prevalence of MRSP was determined according to culture method, EB with MSAox detected the highest prevalence (11.2% [9.1-13.7%]), followed by EB with traditional (10.8% [8.8-13.2%]), traditional (10.1% [8.1-12.5%]), and MSAox (8.9% [7.1-11.2%]). The prevalence using the traditional culture method did not differ significantly from any of the 3 selective culture methods. Culture with MSAox detected significantly fewer MRSP than either of the EB methods. The addition of EB to current methodology is recommended, particularly for patients considered at high risk for MRSP infection
Hazardless nanocomposite for gas barrier potential
No full textComposites based on high density polyethylene (HDPE), ethylene propylene diene monomer (EPDM)
and Organically Modified Montmorillonite (OMMT) clays were made by melt compounding followed by
compression molding. Tensile testing, X-ray diffraction (XRD) and Transmission Electron Microscopy
(TEM) were used to characterize the nanocomposites. The addition of clay, compatibilizer agent (Maleic
Anhydride Polyethylene (MAPE)) and the exposure under Electron Beam Irradiation (EB) considerably
improved the tensile properties of the composite system. Tensile Strength (MPa) and Tensile Modulus
(MPa) were found to increase significantly with increasing clay content and decreasing as the clay content
exceeds 4 wt% values. The largest improvement in composite mechanical properties occurred at clay
loading levels of 4% (2-8 wt %) with EB Irradiation system followed by MAPE and
unirradiated/untreated systems. Nearly 67% increase in tensile strength and 64% increase in tensile
modulus were observed with EB irradiated system. The d spacings of the clay in nanocomposite were
monitored using XRD and the extent of delamination was examined by TEM. The wide angle of XRD
patterns showed the increased d-spacing of clay layers, indicating enhanced compatibility between HDPE
and OMMT with the EB irradiated and addition of MAPE. TEM photomicrographs illustrated the
intercalated and partially exfoliated structures of the nanocomposite with OMMT and MAPE system
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