Advanced materials research for long-haul aircraft turbine engines

The status of research efforts to apply low to intermediate temperature composite materials and advanced high temperature materials to engine components is reviewed. Emerging materials technologies and their potential benefits to aircraft gas turbines were emphasized. The problems were identified, and the general state of the technology for near term use was assessed

Extrusion of small-diameter, thin-wall tungsten tubing

Small-diameter, thin-wall seamless tubing of tungsten has been fabricated in lengths of up to 10 feet by hot extrusion over a floating mandrel. Extrusion of 0.50-inch-diameter tubing over 0.4-inch-diameter mandrels was accomplished at temperatures ranging from 3000 degrees to 4000 degrees F

SOAR (Support Office for Aerogeophysical Research) Annual Report 1994/1995

The Support Office for Aerogeophysical Research (SOAR) was a facility of the National Science Foundation's Office of Polar Programs whose mission is to make airborne geophysical observations available to the broad research community of geology, glaciology and other sciences. The central office of the SOAR facility is located in Austin, Texas within the University of Texas Institute for Geophysics. Other institutions with significant responsibilities are the Lamont­ Doherty Earth Observatory of Columbia University and the Geophysics Branch of the U.S . Geological Survey. This report summarizes the goals and accomplishments of the SOAR facility during 1994/1995 and plans for the next year.National Science Foundation's Office of Polar ProgramsInstitute for Geophysic

Steady state forced response of a mechanical oscillator with combined parametric excitation and clearance type non-linearity

International audienceA mechanical system exhibiting combined parametric excitation and clearance type non-linearity is examined analytically and experimentally in an effort to explain complex behavior that is commonly observed in the steady state forced response of rotating machines. The specific case of a preloaded mechanical oscillator having a periodically time-varying stiffness function and subject to a symmetric backlash condition is considered. A generalized solution methodology is proposed based on the harmonic balance method. The resulting non-linear algebraic equations are solved by using a direct Newton-Raphson technique, in which a closed form Jacobian matrix is computed using frequency domain methods. Analytical solutions are validated by comparison with numerical integration results and experimental measurements obtained from a gear dynamics test rig

Experimental Overlay of Glazon over Two Bridge Decks

In accordance with a Personal Service Agreement entered into with the Glazon Industries, Inc., on July 2, 1971, the two subject decks were patched and overlayed with Glazon. On July 27, 1971, work started on RP 106-286-HG3, KY 395 bridge over I 64 in Shelby County. Work consisted of routing old concrete and sandblasting the surface (Figures 1 and 2). State personnel and equipment were used for all cleaning operations. The same procedures were followed to clean HM 99-1324A-MB3 in Powell County near Clay City. On July 28, 1971, Glazon personnel and equipment arrived at the work site in Shelby County. Glazon representatives judged the cleaning adequate and proceeded with patching the southbound lane (Figure 3). No accurate information is available as to the exact formulation of the Glazon used or proportions in the mix. Glazon Industries declined disclosure of such information since their material was not patented. Before patching, the holes were thoroughly dried. Shrinkage and cracking were noticed in the patches shortly after drying (Figure 4). Later, on other lanes, patch holes were primed with a Glazon liquid before patching (Figures 5 and 6). After a short drying period, the deck was sprayed with a Glazon mix similar to that for patching but more fluid (Figures 7 and 8). Some problems were encountered due to weak air supply, but were shortly overcome. The sprayed deck looked satisfactory to Glazon personnel who did most of the work in patching and overlaying the deck. The operation was moved to the Clay City bridge and the same procedures were followed in working the northbound lane. Two wingwalls on the Shelby County bridge were sprayed with a Glazon mix made with white cement. On August 3, 1971, both bridges were completed though work was interrupted by rain several times. On August 5, 1971, both bridges were reopened to two-lane traffic. This Division closely observed these operations from the beginning. It was later learned from the Division of Maintenance that the northbound lane of the Shelby County deck, which was badly deteriorating, had been repaired on September 15, 1971

Effect of forward motion on engine noise

Methods used to determine a procedure for correcting static engine data for the effects of forward motion are described. Data were analyzed from airplane flyover and static-engine tests with a JT8D-109 low-bypass-ratio turbofan engine installed on a DC-9-30, with a CF6-6D high-bypass-ratio turbofan engine installed on a DC-10-10, and with a JT9D-59A high-bypass-ratio turbofan engine installed on a DC-10-40. The observed differences between the static and the flyover data bases are discussed in terms of noise generation, convective amplification, atmospheric propagation, and engine installation. The results indicate that each noise source must be adjusted separately for forward-motion and installation effects and then projected to flight conditions as a function of source-path angle, directivity angle, and acoustic range relative to the microphones on the ground

Benchmarking calculations of excitonic couplings between bacteriochlorophylls

Excitonic couplings between (bacterio)chlorophyll molecules are necessary for simulating energy transport in photosynthetic complexes. Many techniques for calculating the couplings are in use, from the simple (but inaccurate) point-dipole approximation to fully quantum-chemical methods. We compared several approximations to determine their range of applicability, noting that the propagation of experimental uncertainties poses a fundamental limit on the achievable accuracy. In particular, the uncertainty in crystallographic coordinates yields an uncertainty of about 20% in the calculated couplings. Because quantum-chemical corrections are smaller than 20% in most biologically relevant cases, their considerable computational cost is rarely justified. We therefore recommend the electrostatic TrEsp method across the entire range of molecular separations and orientations because its cost is minimal and it generally agrees with quantum-chemical calculations to better than the geometric uncertainty. We also caution against computationally optimizing a crystal structure before calculating couplings, as it can lead to large, uncontrollable errors. Understanding the unavoidable uncertainties can guard against striving for unrealistic precision; at the same time, detailed benchmarks can allow important qualitative questions--which do not depend on the precise values of the simulation parameters--to be addressed with greater confidence about the conclusions

Taking a Day off to Pray: Closing Schools for Religious Observance in Increasingly Diverse Schools

States and public schools across the Nation consistently debate the number of days students must be in attendance, the length of the day, and the configuration of those days to maximize learning opportunities. Establishing the school calendar within each state’s statutory minimum can be challenging as many states still maintain somewhat traditional (albeit antiquated) calendars, which commence the school year around Labor Day and conclude shortly after June begins.1 Public schools are generally in session for 180 school days. Some states have been more creative in their scheduling by reducing the number of days required of student attendance in favor of expanded school days, citing reduced costs. Attempting to schedule 180 school days in the period of late August through early June does not provide schools with much flexibility should they be required to close for exigent circumstances such as inclement weather. Providing students with additional days off for holidays and religious observances only increases the complexity of meeting the required number of school days in a respective state given these calendar constraints

Laid To Rust: Proposing Strict Liability in Tort for Prop Firearm Injuries Following the Alec Baldwin Shooting

Prop gun safety standards are often a mixed bag. “Despite some industry reforms following previous tragedies, the federal workplace safety agency in the U.S. is silent on the issue of on-set gun safety.” Some states follow film labor union and movie studio guidelines. Other states have regulations on pyrotechnic devices, but not on prop guns. Thus, states should consider what successful legal course of action a wrongfully deceased heir can bring in the event that no criminal charges can be filed. This article proposes that the best regulatory approach and tort liability course of action is through (1) treating prop guns the same as a pyrotechnic device, and (2) characterizing the use of prop guns on-set as an abnormally or inherently dangerous activity for purposes of strict liability, should no criminal charges be granted. Part I provides both a mechanical and historical overview of the use of prop weapons in film and television. Part II further explains how props are regulated. Parts III and IV analyze the tort legal framework and explain why strict liability analysis is best suited for injuries caused by such prop gun devices