9,152 research outputs found
Skylab experiment performance evaluation manual
A series of preparation analyses used for evaluating the performance of the Skylab corollary experiments under preflight, in-flight, and postflight conditions is given. Experiment continegency plan work-around procedure and malfunction analyses are presented in order to assist in making the experiment operationally succesful
Auto covariance computer
A laser velocimeter covariance processor which calculates the auto covariance and cross covariance functions for a turbulent flow field based on Poisson sampled measurements in time from a laser velocimeter is described. The device will process a block of data that is up to 4096 data points in length and return a 512 point covariance function with 48-bit resolution along with a 512 point histogram of the interarrival times which is used to normalize the covariance function. The device is designed to interface and be controlled by a minicomputer from which the data is received and the results returned. A typical 4096 point computation takes approximately 1.5 seconds to receive the data, compute the covariance function, and return the results to the computer
MS-171: Corporal Luther Jacob “Jake” Thomas Papers
This collection consists of letters, photographs, documents, and artifacts relating to Luther J. “Jake” Thomas’s military service during the Second World War. The majority of the collection features correspondence between Thomas and his family, particularly his mother Anna Thomas, between 1943 and 1945. While serving as an MP in the Army Air Corps, Thomas regularly mailed letters and photographs home detailing his training, travels, and experiences as a soldier. The collection also includes Thomas’s military documentation (for example, induction and separation papers), training materials, wartime souvenirs and artefacts, and post-war awards and honors. The collection includes documents related to Thomas’s veteran status following his discharge in late 1945, as well as his subsequent enrollment in the Philadelphia College of Pharmacy. Finally, the collection contains general information about the Thomas family, including photographs, obituaries, and documents concerning Luther C. Thomas (Thomas’s father)’s military service in World War I.
Special Collections and College Archives Finding Aids are discovery tools used to describe and provide access to our holdings. Finding aids include historical and biographical information about each collection in addition to inventories of their content. More information about our collections can be found on our website http://www.gettysburg.edu/special_collections/collections/.https://cupola.gettysburg.edu/findingaidsall/1142/thumbnail.jp
Exhaust emissions reduction for intermittent combustion aircraft engines
Three concepts which, to an aircraft piston engine, provide reductions in exhaust emissions of hydrocarbons and carbon monoxide while simultaneously improving fuel economy. The three chosen concepts, (1) an improved fuel injection system, (2) an improved cooling cylinder head, and (3) exhaust air injection, when combined, show a synergistic relationship in achieving these goals. In addition, the benefits of variable ignition timing were explored and both dynamometer and flight testing of the final engine configuration were accomplished
Screening analysis and selection of emission reduction concepts for intermittent combustion aircraft engines
An analysis was conducted to screen, evaluate, and select three engine exhaust emission reduction concepts from a group of 14 candidate alternatives. A comprehensive literature search was conducted to survey the emission reduction technology state-of-the-art and establish contact with firms working on intermittent combustion engine development and pollution reduction problems. Concept development, advantages, disadvantages, and expected emission reduction responses are stated. A set of cost effectiveness criteria was developed, appraised for relative importance, and traded off against each concept so that its merit could be determined. A decision model was used to aid the evaluators in managing the criteria, making consistent judgements, calculating merit scores, and ranking the concepts. An Improved Fuel Injection System, Improved Cooling Combustion Chamber, and a Variable Timing Ignition System were recommended to NASA for approval and further concept development. An alternate concept, Air Injection, was also recommended
Dynamics of Epidemics
This article examines how diseases on random networks spread in time. The
disease is described by a probability distribution function for the number of
infected and recovered individuals, and the probability distribution is
described by a generating function. The time development of the disease is
obtained by iterating the generating function. In cases where the disease can
expand to an epidemic, the probability distribution function is the sum of two
parts; one which is static at long times, and another whose mean grows
exponentially. The time development of the mean number of infected individuals
is obtained analytically. When epidemics occur, the probability distributions
are very broad, and the uncertainty in the number of infected individuals at
any given time is typically larger than the mean number of infected
individuals.Comment: 4 pages and 3 figure
Laser velocimeter systems analysis applied to a flow survey above a stalled wing
A laser velocimeter operating in the backscatter mode was used to survey the flow above a stalled wing. Polarization was used to separate the two orthogonal velocity components of the fringe-type laser velocimeter, and digital counters were used for data processing. The velocities of the kerosene seed particles were measured with less than 2 percent uncertainty. The particle velocity measurements were collected into histograms. The flow field survey was carried out above an aspect-ratio-8 stalled wing with an NACA 0012 section. The angle of attack was 19.5 deg, the Mach number was 0.49, and the Reynolds number was 1,400,000. The flow field was characterized by the periodic shedding of discrete vortices from near the crest of the airfoil
Epitaxial growth of (111)-oriented LaAlO/LaNiO ultra-thin superlattices
The epitaxial stabilization of a single layer or superlattice structures
composed of complex oxide materials on polar (111) surfaces is severely
burdened by reconstructions at the interface, that commonly arise to neutralize
the polarity. We report on the synthesis of high quality LaNiO/mLaAlO
pseudo cubic (111) superlattices on polar (111)-oriented LaAlO, the
proposed complex oxide candidate for a topological insulating behavior.
Comprehensive X-Ray diffraction measurements, RHEED, and element specific
resonant X-ray absorption spectroscopy affirm their high structural and
chemical quality. The study offers an opportunity to fabricate interesting
interface and topology controlled (111) oriented superlattices based on
ortho-nickelates
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