22,704 research outputs found
Making aerospace technology work for the automotive industry, introduction
NASA derived technology already in use in the automotive industry include: (1) developments in electronics design, computer systems, and quality control methods for line testing of cars and trucks; (2) a combustion analysis computer program for automotive engine research and development; (3) an infrared scanner and television display for analyzing tire design and performance, and for studying the effects of heat on the service life of V-belts, shock mounts, brakes, and rubber bearings; (4) exhaust gas analyzers for trouble shooting and emissions certification; (5) a device for reducing noise from trucks; and (6) a low cost test vehicle for measuring highway skid resistance. Services offered by NASA to facilitate access to its technology are described
Nonaerospace uses of chemical rocket technology
Nonaerospace uses of chemical rocket technolog
Mechanical component screening for scanner
The critical mechanical components of the scan mirror mechanism are described and their evaluation and screening procedures are discussed. A bumper/damper unit is used in the design to reverse motion of the mirror and effect scan and retrace cycles. A wear evaluation was conducted on the bumper impact surfaces that established nylon 6-10 as an acceptable material. The elastomeric dampers were subjected to thermal vacuum tests for condensables and outgassing as well as parametric life tests. The flexure pivots that support the mirror were tested to establish a curve of stress plotted as a function of cycles to failure for rotational operation. The pivots met the life requirement of 150,000,000 cycles at a + or - 2.9 deg amplitude during fatigue testing. Screening procedures were established for dampers and flexure pivots to obtain flight quality components
Scaling properties of noise-induced switching in a bistable tunnel diode circuit
Noise-induced switching between coexisting metastable states occurs in a wide
range of far-from-equilibrium systems including micro-mechanical oscillators,
epidemiological and climate change models, and nonlinear electronic transport
in tunneling structures such as semiconductor superlattices and tunnel diodes.
In the case of tunnel diode circuits, noise-induced switching behavior is
associated with negative differential resistance in the static current-voltage
characteristics and bistability, i.e., the existence of two macroscopic current
states for a given applied voltage. Noise effects are particularly strong near
the onset and offset of bistable current behavior, corresponding to bifurcation
points in the associated dynamical system. In this paper, we show that the
tunnel diode system provides an excellent experimental platform for the
precision measurement of scaling properties of mean switching times versus
applied voltage near bifurcation points. More specifically, experimental data
confirm that the mean switching time scales logarithmically as the 3/2 power of
voltage difference over an exceptionally wide range of time scales and noise
intensities.Comment: 9 pages, 9 figures, accepted manuscript for publication in the
European Physical Journal B, Topical Issue: Non-Linear and Complex Dynamics
in Semiconductors and Related Material
Development of the elevation drive assembly for orbiting solar observatory I (EYE)
The requirements for pointing accuracy, friction, and power for the elevation drive assembly of an orbiting space observatory are discussed briefly. A description of the components making up the assembly is presented. Special features requiring development testing prior to unit fabrication are more fully described together with a review of the test programs conducted and results obtained
An Unusual Cause of Abdominal Ascites.
Abdominal ascites is most commonly caused by portal hypertension from liver cirrhosis. When present, portal hypertension is associated with an elevated serum-ascites albumin gradient (SAAG) ≥1.1 g/dL. In contrast, a SAAG < 1.1 g/dL suggests malignancy, tuberculosis, pancreatitis, or nephrotic syndrome. Here, we present a case of low SAAG ascites caused by epithelioid peritoneal mesothelioma in a woman with no known liver disease. The diagnosis proved elusive until diagnostic laparoscopy with biopsy was performed
Recommended from our members
Peer crowd-based targeting in E-cigarette advertisements: a qualitative study to inform counter-marketing.
BACKGROUND:Cigarette lifestyle marketing with psychographic targeting has been well documented, but few studies address non-cigarette tobacco products. This study examined how young adults respond to e-cigarette advertisements featuring diverse peer crowds - peer groups with shared identities and lifestyles - to inform tobacco counter-marketing design. METHODS:Fifty-nine young adult tobacco users in California participated in interviews and viewed four to five e-cigarette advertisements that featured characters from various peer crowd groups. For each participant, half of the advertisements they viewed showed characters from the same peer crowd as their own, and the other half of the advertisements featured characters from a different peer crowd. Advertisements were presented in random order. Questions probed what types of cues are noticed in the advertisements, and whether and how much participants liked or disliked the advertisements. RESULTS:Results suggest that participants liked and provided richer descriptions of characters and social situations in the advertisements featuring their own peer crowd more than the advertisements featuring a different peer crowd. Mismatching age or device type was also noted: participants reported advertisements showing older adults were not intended for them. Participants who used larger vaporizers tended to dislike cigalike advertisements even if they featured a matching peer crowd. CONCLUSION:Peer crowd and lifestyle cues, age and device type are all salient features of e-cigarette advertising for young adults. Similarly, educational campaigns about e-cigarettes should employ peer crowd-based targeting to engage young adults, though messages should be carefully tested to ensure authentic and realistic portrayals
A Limited Habitable Zone for Complex Life
The habitable zone (HZ) is commonly defined as the range of distances from a
host star within which liquid water, a key requirement for life, may exist on a
planet's surface. Substantially more CO2 than present in Earth's modern
atmosphere is required to maintain clement temperatures for most of the HZ,
with several bars required at the outer edge. However, most complex aerobic
life on Earth is limited by CO2 concentrations of just fractions of a bar. At
the same time, most exoplanets in the traditional HZ reside in proximity to M
dwarfs, which are more numerous than Sun-like G dwarfs but are predicted to
promote greater abundances of gases that can be toxic in the atmospheres of
orbiting planets, such as carbon monoxide (CO). Here we show that the HZ for
complex aerobic life is likely limited relative to that for microbial life. We
use a 1D radiative-convective climate and photochemical models to circumscribe
a Habitable Zone for Complex Life (HZCL) based on known toxicity limits for a
range of organisms as a proof of concept. We find that for CO2 tolerances of
0.01, 0.1, and 1 bar, the HZCL is only 21%, 32%, and 50% as wide as the
conventional HZ for a Sun-like star, and that CO concentrations may limit some
complex life throughout the entire HZ of the coolest M dwarfs. These results
cast new light on the likely distribution of complex life in the universe and
have important ramifications for the search for exoplanet biosignatures and
technosignatures.Comment: Revised including additional discussion. Published Gold OA in ApJ. 9
pages, 5 figures, 5 table
Entanglement between the future and past in the quantum vacuum
We note that massless fields within the future and past light cone may be
quantized as independent systems. We show that the vacuum is an entangled state
of these systems, exactly mirroring the known entanglement between the
spacelike separated Rindler wedges. We describe a detector which exhibits a
thermal response to the vacuum when switched on at t=0. The feasibility of
experimentally detecting this effect is discussed.Comment: 4 pages, 1 figur
- …