3,240 research outputs found
Space Shuttle Stiffener Ring Foam Failure Analysis, a Non-Conventional Approach
The Space Shuttle Program made use of the excellent properties of rigid polyurethane foam for cryogenic tank insulation and as structural protection on the solid rocket boosters. When foam applications de-bond, classical methods of failure analysis did not provide root cause of the failure of the foam. Realizing that foam is the ideal media to document and preserve its own mode of failure, thin sectioning was seen as a logical approach for foam failure analysis to observe the three dimensional morphology of the foam cells. The cell foam morphology provided a much greater understanding of the failure modes than previously achieved
Characterization of Monomethyihydrazine (MMH) Non-Volatile Residue
The Space Shuttle program has a unique propellant purity requirement for determination of nonvolatile residue (NVR) in monomethylhydrazine (MMH). TIis requirement differs from the Military Specification procurement specification by requiring a NVR analysis with a limit of less than or equal to 10 milligrams per liter. In June 2008, a routine MMH replenishment delivery was transferred into a NASA KSC owned tanker for future delivery to the Space Shuffle pad MMH storage tank. Per Shuffle standard operating procedure, the receiving tanker was sampled and analyzed for purity and surprisingly it failed the Shuttle use NVR specification limit. Detailed examination of the NVR revealed that it was fundamentally different than the typical MMH NVR. This paper will examine various aspects of NVR determination in MMH and the analytical characterization processes used to identify the NVR
What Best Explains Successful Protest Cascades? ICT s and the Fuzzy Causes of the Arab Spring
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97489/1/misr12020.pd
Democracy’s Fourth Wave? Digital Media and the Arab Spring
Did digital media really "cause" the Arab Spring, or is it an important factor of the story behind what might become democracy's fourth wave? An unlikely network of citizens used digital media to start a cascade of social protest that ultimately toppled four of the world's most entrenched dictators. Howard and Hussain find that the complex causal recipe includes several economic, political and cultural factors, but that digital media is consistently one of the most important sufficient and necessary conditions for explaining both the fragility of regimes and the success of social movements. This book looks at not only the unexpected evolution of events during the Arab Spring, but the deeper history of creative digital activism throughout the region.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117564/1/Democracy's Fourth Wave.pdfDescription of Democracy's Fourth Wave.pdf : PD
International Space Station EVA Wipe: An Extraordinary Sample from a Far-Out Place
No abstract availabl
Space Shuttle Stiffener Ring Foam Failure, a Non-Conventional Approach
The Space Shuttle makes use of the excellent properties of rigid polyurethane foam for cryogenic tank insulation and as structural protection on the solid rocket boosters. When foam applications debond, classical methods of analysis do not always provide root cause of the failure of the foam. Realizing that foam is the ideal media to document and preserve its own mode of failure, thin sectioning was seen as a logical approach for foam failure analysis. Thin sectioning in two directions, both horizontal and vertical to the application, was chosen to observe the three dimensional morphology of the foam cells. The cell foam morphology provided a much greater understanding of the failure modes than previously achieved
The Dictators’ Digital Dilemma: When Do States Disconnect Their Digital Networks?
When do governments decide to interfere with the Internet, and why? While many observers celebrate the creative use of digital media by activists and civil society leaders, there are a significant number of incidents involving government-led Internet shutdowns. Governments have offered a range of reasons for interfering with digital networks, employed many tactics, and experienced both costs and benefits in doing so.http://deepblue.lib.umich.edu/bitstream/2027.42/117569/1/2011_Howard-Agarwal-Hussain_Brookings.pd
Space Shuttle Stiffener Ring Foam Failure Analysis, A Non-Conventional Approach
No abstract availabl
Space Shuttle Stiffener Ring Foam Failure Analysis, a Non-Conventional Approach.
The Space Shuttle Program made use of the excellent properties of rigid polyurethane foam for cryogenic tank insulation and as structural protection on the solid rocket boosters. When foam applications de-bond, classical methods of failure analysis did not provide root cause of the failure of the foam. Realizing that foam is the ideal media to document and preserve its own mode of failure, thin sectioning was seen as a logical approach for foam failure analysis to observe the three dimensional morphology of the foam cells. The cell foam morphology provided a much greater understanding of the failure modes than previously achieved
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