A laboratory verification sensor

The use of a variant of the Hartmann test is described to sense the coalignment of the 36 primary mirror segments of the Keck 10-meter Telescope. The Shack-Hartmann alignment camera is a surface-tilt-error-sensing device, operable with high sensitivity over a wide range of tilt errors. An interferometer, on the other hand, is a surface-height-error-sensing device. In general, if the surface height error exceeds a few wavelengths of the incident illumination, an interferogram is difficult to interpret and loses utility. The Shack-Hartmann aligment camera is, therefore, likely to be attractive as a development tool for segmented mirror telescopes, particularly at early stages of development in which the surface quality of developmental segments may be too poor to justify interferometric testing. The constraints are examined which would define the first-order properties of a Shack-Hartmann alignment camera and the precision and range of measurement one could expect to achieve with it are investigated. Fundamental constraints do arise, however, from consideration of geometrical imaging, diffraction, and the density of sampling of images at the detector array. Geometrical imagining determines the linear size of the image, and depends on the primary mirror diameter and the f-number of a lenslet. Diffraction is another constraint; it depends on the lenslet aperture. Finally, the sampling density at the detector array is important since the number of pixels in the image determines how accurately the centroid of the image can be measured. When these factors are considered under realistic assumptions it is apparent that the first order design of a Shack-Hartmann alignment camera is completely determined by the first-order constraints considered, and that in the case of a 20-meter telescope with seeing-limited imaging, such a camera, used with a suitable detector array, will achieve useful precision

The NASA Thunderstorm Overflight Program (TOP): Research in atmospheric electricity from an instrumented U-2 aircraft platform

An overview of the NASA Thunderstorm Overflight Program (TOP) is presented. The various instruments flown on the NASA U-2 aircraft, as well as the ground instrumentation used to collect optical and electronic signature from the lightning events, are discussed. Samples of some of the photographic and electronic signatures are presented. Approximately 6400 electronic data samples of optical pulses were collected and are being analyzed

Luminous electrical phenomena in Huntsville, Alabama, tornadoes on April 3, 1974

Unusual lightning and varicolored luminous phenomena were observed on the evening of April 3, 1974, when severe tornadoes passed through Madison County, Alabama. Photographs and eyewitness accounts of this electrical activity are related to the trajectories of the tornadoes and the damage areas they produced

Cryogenic/high temperature structural adhesives

Results are described of the work performed to develop a structural adhesive system which possesses useful properties over a 20K (-423 F) to 589 K (600 F) temperature range. Adhesives systems based on polyimide, polyphenylquinoxaline polyquinoxaline, polybenzothiazole and polybenzimidazole polymers first were screened for suitability. Detailed evaluation of two polyimide adhesive sytems, Br34/FM34 and P4/A5F or P4A/A5FA, and one polyphenylquinoxaline adhesive system, PPQ II (IMW), then was performed. Property information was generated over the full temperature range for shear strength, stressed and unstressed thermal aging, thermal shock and coefficient of thermal expansion. Both polyimide adhesive systems were identified as being capable of providing structural adhesive joints for cryogenic/high temperature service

Thunderstorm observations from Space Shuttle

Results of the Nighttime/Daytime Optical Survey of Lightning (NOSL) experiments done on the STS-2 and STS-4 flights are covered. During these two flights of the Space Shuttle Columbia, the astronaut teams of J. Engle and R. Truly, and K. Mattingly II and H. Hartsfield took motion pictures of thunderstorms with a 16 mm cine camera. Film taken during daylight showed interesting thunderstorm cloud formations, where individual frames taken tens of seconds apart, when viewed as stereo pairs, provided information on the three-dimensional structure of the cloud systems. Film taken at night showed clouds illuminated by lightning with discharges that propagated horizontally at speeds of up to 10 to the 5th m/sec and extended for distances on the order of 60 km or more

Lightning observations from the Space Shuttle

Motion pictures were taken at night from the space shuttle that show lightning discharges spreading horizontally at speeds of .00001 m/sec for distances over 60 km. Tape recordings were made of the accompanying optical pulses detected with a photocell optical system. The observations show that lightning is often a mesoscale phenomenon that conveys large amounts of electric charge and energy derived from an extensive cloud system into a cloud-to-ground discharge. Several video tape recordings of lightning discharges were obtained on shuttle flights since the termination of the NOSL program. The size and location of the lightning illuminated cloud images is now being analyzed, and comparisons are made with meteorological data concerning the cloud system obtained from the McIDAS

Time-domain wave splitting of Maxwell's equations

Wave splitting of the time dependent Maxwell's equations in three dimensions with and without dispersive terms in the constitutive equation is treated. The procedure is similar to the method developed for the scalar wave equation except as follows. The up-and down-going wave condition is expressed in terms of a linear relation between the tangential components of E and H. The resulting system of differential-integral equations for the up-and down-going waves is directly obtained from Maxwell's equations. This splitting (arising from the principal part of Maxwell's equations) is applied to the case where there is dispersion. A formal derivation of the imbedding equation for the reflection operator in a medium with no dispersion is obtained

A Brief Study of the Phonology of the Neapolitan Dialect

The following study concerns itself with the dialect of the city of Naples and, more particularly, with that of the Sezione di Chiaja. Some of the outlying districts, e. g., Campo di Marte, already show some slight variations from the language studied herein. The sources of this study have been both oral and written. The writer first took lessons in conversation, at the same time studying texts, and then, after he had acquired some fluency in the spoken language, he went among the people to verify the results and the conclusions which he had obtained. In addition to this, he profited much from aid given him by others who had made a special study of the dialect. Among these he wishes to thank particularly Signer Alberto Cerbino, actor on the Neapolitan stage and author of several Neapolitan comedies, and Signori Bideri and Izzo, well-known publishers of Canzonette Napoletane

Sustainable Transportation Program 2011 Annual Report

Highlights of selected research and development efforts at Oak Ridge National Laboratory funded by the Vehicle Technologies Program, Biomass Program, and Hydrogen and Fuel Cells Program of the Department of Energy, Office of Energy Efficiency and Renewable Energy; and the Department of Transportation