Laboratory determination of the luminous efficiency of meteor constituents

A crossed beam apparatus has been used to measure the emission and ionization cross sections for the prominent spectral features of Na, Ca, Mg, and Fe in collisions with N2 and O2 over the velocity range of 30 to 120 km/s. From the emission and ionization cross sections, the absolute luminous efficiencies in air were determined over the range of meteor velocities. The maximum luminous efficiencies for the brightest features were: greater than 1 percent for the Na D-lines, 0.2 percent for the Ca I(2) singlet, 0.06 percent for the Mg I(2) and Mg I(3) triplets, and 0.4 percent for Fe over the visible spectral range. These luminous efficiencies are valid for free molecular flow conditions for velocities above about 30 km/s and are directly applicable to spectroscopic observations of faint meteors. In contrast to previous work, the luminous efficiency found for stone in the present investigation decreased with velocity above about 50 km/s

Nonlinear response and failure characteristics of internally pressurized composite cylindrical panels

Results of an experimental and analytical study of the nonlinear response and failure characteristics of internally pressurized 4- to 16-ply-thick graphite-epoxy cylindrical panels are presented. Specimens with clamped boundaries simulating the skin between two frames and two stringers of a typical transport fuselage were tested to failure. Failure results of aluminum specimens are compared with the graphite-epoxy test results. The specimens failed at their edges where the local bending gradients and interlaminar stresses are maximum. STAGS nonlinear two-dimensional shell analysis computer code results are used to identify regions of the panels where the response is independent of the axial coordinate. A geometrically nonlinear one-dimensional cylindrical panel analysis was derived and used to determine panel response and interlaminar stresses. Inclusion of the geometric nonlinearity was essential for accurate prediction of panel response. The maximum stress failure criterion applied to the predicted tensile stress in the fiber direction agreed best with the experimentally determined first damage pressures

Technology and Autism Spectrum Disorders

This meta-synthesis of empirical and non-empirical literature reviewed 43 journal articles that evaluated the availability and use of technology to educate and socialize learners with Autism Spectrum Disorder or Aspersers Disorder. Students with these disorders cannot be defined or categorized each individual is unique and elegant; challenging caregiver's and educator's creativity to teach and guide them toward a quality of life they would not find on their own. There are tools and research to support unique education on many levels of learning from academics to socialization. The literature indicates that while there is a wealth of technology available and new technology is constantly being developed cost can not only prohibit production it can lessen the quality. What gets into the classroom tool box is determined by the tenacity of the educator

Behavior of composite/metal aircraft structural elements and components under crash type loads: What are they telling us

Failure behavior results are presented from crash dynamics research using concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs which incorporate improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures which include individual fuselage frames, skeleton subfloors with stringers and floor beams but without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static and dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models. It is believed that the similarity in behavior is giving the designer and dynamists much information about what to expect in the crash behavior of these structures and can guide designs for improving the energy absorption and crash behavior of such structures

Helicopter crashworthiness research program

Results are presented from the U.S. Army-Aerostructures Directorate/NASA-Langley Research Center joint research program on helicopter crashworthiness. Through the on-going research program an in-depth understanding was developed on the cause/effect relationships between material and architectural variables and the energy-absorption capability of composite material and structure. Composite materials were found to be efficient energy absorbers. Graphite/epoxy subfloor structures were more efficient energy absorbers than comparable structures fabricated from Kevlar or aluminum. An accurate method predicting the energy-absorption capability of beams was developed

Temperature dependency of the photoabsorption cross section for CF2Cl2

The photoabsorption cross section for CF2CL2 is measured at 297 K and 200 K. Cross sections are obtained for the ground and first two vibrationally excited states, allowing for a determination of the photoabsorption as a function of temperature over the range of stratospheric interest

An overview of the crash dynamics failure behavior of metal and composite aircraft structures

An overview of failure behavior results is presented from some of the crash dynamics research conducted with concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. Experimental and analytical data are presented that indicate some general trends in the failure behavior of a class of composite structures that includes fuselage panels, individual fuselage sections, fuselage frames, skeleton subfloors with stringers and floor beams without skin covering, and subfloors with skin added to the frame stringer structure. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models

A review of the analytical simulation of aircraft crash dynamics

A large number of full scale tests of general aviation aircraft, helicopters, and one unique air-to-ground controlled impact of a transport aircraft were performed. Additionally, research was also conducted on seat dynamic performance, load-limiting seats, load limiting subfloor designs, and emergency-locator-transmitters (ELTs). Computer programs were developed to provide designers with methods for predicting accelerations, velocities, and displacements of collapsing structure and for estimating the human response to crash loads. The results of full scale aircraft and component tests were used to verify and guide the development of analytical simulation tools and to demonstrate impact load attenuating concepts. Analytical simulation of metal and composite aircraft crash dynamics are addressed. Finite element models are examined to determine their degree of corroboration by experimental data and to reveal deficiencies requiring further development

Attoyac Bayou GIS Inventory, Source Survey and Land Use Cover Report

The Attoyac Bayou watershed is one of many rural watersheds included in the Texas Water Quality Inventory and 303(d) List as an impaired water body due to excessive E. coli levels. In many cases the assessed data in these waterbodies is limited and information regarding potential sources of pollution or other factors that may influence the presence of pollutant sources is not readily available. To address this need, a comprehensive geographic information system (GIS) inventory of the watershed will be developed and will integrate numerous existing information resources into a single location. Generally, the GIS will illustrate waterbodies, roadways, permitted point-source dischargers, and other points of concern. Additionally, current land use/land cover (LULC) maps for the watershed will be updated. Existing LULC layers will be utilized as a starting point and will be re-delineated utilizing groundtruthed data points collected for the GIS inventory to verify the accuracy of the LULC map. Through the development of the GIS and update of the LULC maps, a physical source survey will also be conducted across the watershed to document the primary sources of bacteria in the watershed

The Cost of Participation: Reducing Response Effort to Increase Participation and Quality in Peer-To-Peer Observations

Behavior-based safety (BBS) systems have shown to be effective in decreasing injury rates in industry. Typical BBS systems use a peer-to-peer observation via a critical behavior checklist (CBC) to measure the rates of safe and at-risk behavior for observed employees. A key feature of these programs is quality participation. The current study sought to test if using a shorter CBC with a few behaviors (5-8) would increase quality participation in BBS systems. No such increases were observed. Instead, results indicated that many employees did not utilize the new eight-behavior CBC. Interviews with managers on each vessel revealed that implementation methods on each vessel varied considerably. Furthermore, many employees relied on memory, rather than using a CBC. The implications of inconsistent implementation and memory reliance are discussed