297 research outputs found

    A critical assessment of UH-60 main rotor blade airfoil data

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    Many current comprehensive rotorcraft analyses employ lifting-line methods that require main rotor blade airfoil data, typically obtained from wind tunnel tests. In order to effectively evaluate these lifting-line methods, it is of the utmost importance to ensure that the airfoil section data are free of inaccuracies. A critical assessment of the SC1095 and SC1094R8 airfoil data used on the UH-60 main rotor blade was performed for that reason. Nine sources of wind tunnel data were examined, all of which contain SC1095 data and four of which also contain SC1094R8 data. Findings indicate that the most accurate data were generated in 1982 at the 11-Foot Wind Tunnel Facility at NASA Ames Research Center and in 1985 at the 6-inch by 22-inch transonic wind tunnel facility at Ohio State University. It has not been determined if data from these two sources are sufficiently accurate for their use in comprehensive rotorcraft analytical models of the UH-60. It is recommended that new airfoil tables be created for both airfoils using the existing data. Additional wind tunnel experimentation is also recommended to provide high quality data for correlation with these new airfoil tables

    The influence of mass tourism and hygroscopic inertia in relative humidity fluctuations of museums located in historical buildings

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    The preservation of artefacts in museum collections is profoundly affected by fluctuations in temperature and relative humidity. This work presents the results of an experimental laboratorial study, conducted in a flow chamber to demonstrate the enormous potential of hygroscopic materials in stabilizing interior relative humidity. In order to assess the risk of mass tourism and hygroscopic inertia of finishing materials, associated with the hygrothermal behavior of museums, an analysis of several numerical scenarios, with a different number of visitors per hour, and finishing materials, in order to quantify the risks associated with the fluctuations of relative humidity. The results of sensitivity studies performed are presented for the case of a museum in Porto

    Echocardiographic Confirmation of Mitral Valve Prolapse: A New Finding on Radionuclide Ventriculography- A Case Report

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    A prominent filling defect was depicted on a radionuclide ventriculogram in a patient with mitral regurgitation. This defect was later shown, by cardiac ultrasound, to be due to mitral valve prolapse into the left ventricle during diastole. This case illustrates that mitral valve prolapse should be added to the list of clinical entities that can result in an intraventricular defect on a radionu clide ventriculogram.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67208/2/10.1177_000331978904000209.pd

    Corporate governance and employees in South Africa.

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    Focusing on employees as stakeholders, we analyse corporate governance initiatives in South Africa encouraging and requiring companies to look beyond their shareholders' interests. Successive non-binding codes and the provisions of the recent Companies Act 2008 promoting this have been lauded by many commentators. The 2008 Act provides certain opportunities for employees and their representatives to exercise influence at the margins. We nevertheless question how far current corporate governance initiatives are adequate to promote employee interests. On the basis of three case studies of how companies have responded to employees as stakeholders, we conclude that in fact more stringent regulation is required

    Radio-guided Surgery for Non-131 I-avid Thyroid Cancer

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63206/1/thy.2006.16.1105.lowlink.pdf_v03.pd

    Shock enhancement and control of hypersonic mixing and combustion

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    Computed tomography as an adjunct to ultrasound in the diagnosis of acute acalculous cholecystitis

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    The sonographic and computed tomographic (CT) findings were reviewed in 17 patients with acute acalculous cholecystitis (AAC) over a 6-year period from 1984 to 1989. Of the six patients in whom both ultrasound and CT were performed, CT revealed marked gallbladder (GB) wall abnormalities, including perforation, and pericholecystic fluid collections in five patients not demonstrated by sonography. Of the total group, five patients had GB wall thicknesses of ≤ 3 mm (normal) at pathologic examination, which demonstrated a spectrum of disease ranging from acute hemorrhagic/necrotizing, to gangrenous acalculous cholecystitis with perforation. Sonography was falsely negative or significantly underestimated the severity of AAC in seven of the 13 patients examined by sonography. CT because of its superior ability to assess pericholecystic inflammation may provide additional diagnostic information even after a thorough sonographic study in cases of AAC.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48138/1/261_2005_Article_BF01887331.pd
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