2,190 research outputs found
Observation of Damage Growth in Compressively Loaded Laminates
An experimental program to determine tie phenomenological aspects of composite-panel failure under simultaneous compressive n-plane loading and low-velocity transverse impact [C-75 m/s (0-250 ft/s)] is described. High-speed photography coupled with the shadow-moiré technique is used to record the phenomenon of failure propagation. The information gained from these records, supplemented by plate sectioning and observation for interior damage, has provided information regarding the failure-propagation mechanism.
The results show that the failure process can be divided roughly into two phases. In the first phase the plane is impacted, and the resulting response causes interlaminar separation. In the second phase the local damage spreads to the undamaged portion of the plate through a combination of laminae buckling and further delamination
Preventing respiratory viral transmission in long-term care: Knowledge, attitudes, and practices of healthcare personnel
OBJECTIVETo examine knowledge and attitudes about influenza vaccination and infection prevention practices among healthcare personnel (HCP) in a long-term-care (LTC) setting.DESIGNKnowledge, attitudes, and practices (KAP) survey.SETTINGAn LTC facility in St Louis, Missouri.PARTICIPANTSAll HCP working at the LTC facility were eligible to participate, regardless of department or position. Of 170 full- and part-time HCP working at the facility, 73 completed the survey, a 42.9% response rate.RESULTSMost HCP agreed that respiratory viral infections were serious and that hand hygiene and face mask use were protective. However, only 46% could describe the correct transmission-based precautions for an influenza patient. Correctly answering infection prevention knowledge questions did not vary by years of experience but did vary for HCP with more direct patient contact versus less patient contact. Furthermore, 42% of respondents reported working while sick, and 56% reported that their coworkers did. In addition, 54% reported that facility policies made staying home while ill difficult. Some respondents expressed concerns about the safety (22%) and effectiveness (27%) of the influenza vaccine, and 28% of respondents stated that they would not get the influenza vaccine if it was not required.CONCLUSIONSThis survey of staff in an LTC facility identified several areas for policy improvement, particularly sick leave, as well as potential targets for interventions to improve infection prevention knowledge and to address HCP concerns about influenza vaccination to improve HCP vaccination rates in LTCs.Infect Control Hosp Epidemiol 2017;38:1449–1456</jats:sec
Evaluation of aircraft microwave data for locating zones for well stimulation and enhanced gas recovery
Imaging radar was evaluated as an adjunct to conventional petroleum exploration techniques, especially linear mapping. Linear features were mapped from several remote sensor data sources including stereo photography, enhanced LANDSAT imagery, SLAR radar imagery, enhanced SAR radar imagery, and SAR radar/LANDSAT combinations. Linear feature maps were compared with surface joint data, subsurface and geophysical data, and gas production in the Arkansas part of the Arkoma basin. The best LANDSAT enhanced product for linear detection was found to be a winter scene, band 7, uniform distribution stretch. Of the individual SAR data products, the VH (cross polarized) SAR radar mosaic provides for detection of most linears; however, none of the SAR enhancements is significantly better than the others. Radar/LANDSAT merges may provide better linear detection than a single sensor mapping mode, but because of operator variability, the results are inconclusive. Radar/LANDSAT combinations appear promising as an optimum linear mapping technique, if the advantages and disadvantages of each remote sensor are considered
Visualization of impact damage of composite plates by means of the Moire technique
The phenomenological aspects of propagation damage due to low velocity impact on heavily loaded graphite-epoxy composite laminates were investigated using high speed photography coupled with the moire fringe technique. High speed moire motion records of the impacted specimens are presented. The results provide information on the time scale and sequence of the failure process. While the generation of the initial damage cannot always be separated temporally from the spreading of the damage, the latter takes place on the average with a speed on the order of 200 m/sec
Buffalo National River Ecosystems - Part II
The priorities were established for the Buffalo National River Ecosystem Studies through meetings and correspondence with Mr. Roland Wauer and other personnel of the Office of Natural Sciences, Southwest Region of the National Park Service. These priorities were set forth in the appendix of contract no. CX 700050443 dated May 21, 1975
Final Report: Buffalo National River Ecosystems
The objective of this study was to sample the Buffalo River on a seasonal basis for a year, in order to determine whether any potential water quality problems existed
Randomized controlled trial to determine the impact of probiotic administration on colonization with multidrug-resistant organisms in critically ill patients
This was a randomized controlled pilot study of Lactobacillus rhamnosus GG versus standard of care to prevent gastrointestinal multidrug-resistant organism (MDRO) colonization in ICU patients. Seventy subjects were included in analyses. There were no significant differences in acquisition or loss of any MDROs (p>0.05). There were no probiotic-associated adverse events
The laboratory telerobotic manipulator program
New opportunities for the application of telerobotic systems to enhance human intelligence and dexterity in the hazardous environment of space are presented by the NASA Space Station Program. Because of the need for significant increases in extravehicular activity and the potential increase in hazards associated with space programs, emphasis is being heightened on telerobotic systems research and development. The Laboratory Telerobotic Manipulator (LTM) program is performed to develop and demonstrate ground-based telerobotic manipulator system hardware for research and demonstrations aimed at future NASA applications. The LTM incorporates traction drives, modularity, redundant kinematics, and state-of-the-art hierarchical control techniques to form a basis for merging the diverse technological domains of robust, high-dexterity teleoperations and autonomous robotic operation into common hardware to further NASA's research
Pattern selection as a nonlinear eigenvalue problem
A unique pattern selection in the absolutely unstable regime of driven,
nonlinear, open-flow systems is reviewed. It has recently been found in
numerical simulations of propagating vortex structures occuring in
Taylor-Couette and Rayleigh-Benard systems subject to an externally imposed
through-flow. Unlike the stationary patterns in systems without through-flow
the spatiotemporal structures of propagating vortices are independent of
parameter history, initial conditions, and system length. They do, however,
depend on the boundary conditions in addition to the driving rate and the
through-flow rate. Our analysis of the Ginzburg-Landau amplitude equation
elucidates how the pattern selection can be described by a nonlinear eigenvalue
problem with the frequency being the eigenvalue. Approaching the border between
absolute and convective instability the eigenvalue problem becomes effectively
linear and the selection mechanism approaches that of linear front propagation.
PACS: 47.54.+r,47.20.Ky,47.32.-y,47.20.FtComment: 18 pages in Postsript format including 5 figures, to appear in:
Lecture Notes in Physics, "Nonlinear Physics of Complex Sytems -- Current
Status and Future Trends", Eds. J. Parisi, S. C. Mueller, and W. Zimmermann
(Springer, Berlin, 1996
The radio lighthouse CU Virginis: the spindown of a single main sequence star
The fast rotating star CU Virginis is a magnetic chemically peculiar star
with an oblique dipolar magnetic field. The continuum radio emission has been
interpreted as gyrosyncrotron emission arising from a thin magnetospheric
layer. Previous radio observations at 1.4 GHz showed that a 100% circular
polarized and highly directive emission component overlaps to the continuum
emission two times per rotation, when the magnetic axis lies in the plane of
the sky. This sort of radio lighthouse has been proposed to be due to cyclotron
maser emission generated above the magnetic pole and propagating
perpendicularly to the magnetic axis. Observations carried out with the
Australia Telescope Compact Array at 1.4 and 2.5 GHz one year after this
discovery show that this radio emission is still present, meaning that the
phenomenon responsible for this process is steady on a timescale of years. The
emitted radiation spans at least 1 GHz, being observed from 1.4 to 2.5 GHz. On
the light of recent results on the physics of the magnetosphere of this star,
the possibility of plasma radiation is ruled out. The characteristics of this
radio lighthouse provides us a good marker of the rotation period, since the
peaks are visible at particular rotational phases. After one year, they show a
delay of about 15 minutes. This is interpreted as a new abrupt spinning down of
the star. Among several possibilities, a quick emptying of the equatorial
magnetic belt after reaching the maximum density can account for the magnitude
of the breaking. The study of the coherent emission in stars like CU Vir, as
well as in pre main sequence stars, can give important insight into the angular
momentum evolution in young stars. This is a promising field of investigation
that high sensitivity radio interferometers such as SKA can exploit.Comment: Accepted to MNRAS, 8 pages, 7 figures, updated versio
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