53,789 research outputs found
A New Bot Fly Species (Diptera: Oestridae) From Central Texas
The bot fly Cephenemyia albina (Diptera: Oestridae) is described from a relict pine forest in east-central Texas. This species presumably lives as a parasitic larva in the throat of white-tailed deer as do its two close relatives previously reported from both Texas and the Great Lakes region (C. phobifera (Clark) and C. jellisoni Townsend). Only the adult male is currently known
A statistical study of the surface accuracy of a planar truss beam
Surface error statistics for single-layer and double-layer planar truss beams with random member-length errors were calculated using a Monte-Carlo technique in conjunction with finite-element analysis. Surface error was calculated in terms of the normal distance from a regression line to the surface nodes of the distorted beam. Results for both single-layer and double-layer beams indicate that a minimum root-mean-square surface error can be achieved by optimizing the depth-to-length ratio of a truss beam. The statically indeterminate double-layer beams can provide greater surface accuracy, though at the expense of significantly greater complexity
Wave techniques for noise modeling and measurement
The noise wave approach is applied to analysis, modeling, and measurement applications. Methods are presented for the calculation of component and network noise wave correlation matrices. Embedding calculations, relations to two-port figures-of-merit, and transformations to traditional representations are discussed. Simple expressions are derived for MESFET and HEMT noise wave parameters based on a linear equivalent circuit. A noise wave measurement technique is presented and experimentally compared with the conventional method
Multinomial selection index
Comparison of multivariate statistical analysis techniques for multinomial selection indice
Atmospheric contaminant sensor. Book 2: Appendices
Appendices containing equipment specifications and performance test data of the atmospheric contaminant sensor for submarines are presented
Speed control with low armature loss for very small sensorless brushed DC motors
A method for speed control of brushed dc motors is presented. It is particularly applicable to motors with armatures of less than 1 cm3. Motors with very small armatures are difficult to control using the usual pulsewidth-modulation (PWM) approach and are apt to overheat if so driven. The technique regulates speed via the back electromotive force but does not require current-discontinuous drives. Armature heating in small motors under PWM drive is explained and quantified. The method is verified through simulation and measurement. Control is improved, and armature losses are minimized. The method can expect to find application in miniature mechatronic equipment
The Invisible Majority? Evolution and Detection of Outer Planetary Systems without Gas Giants
We present 230 realizations of a numerical model of planet formation in
systems without gas giants. These represent a scenario in which protoplanets
grow in a region of a circumstellar disk where water ice condenses (the "ice
line''), but fail to accrete massive gas envelopes before the gaseous disk is
dispersed. Each simulation consists of a small number of gravitationally
interacting oligarchs and a much larger number of small bodies that represent
the natal disk of planetesimals. We investigate systems with varying initial
number of oligarchs, oligarch spacing, location of the ice line, total mass in
the ice line, and oligarch mean density. Systems become chaotic in ~1 Myr but
settle into stable configurations in 10-100 Myr. We find: (1) runs consistently
produce a 5-9 Earth mass planet at a semimajor axis of 0.25-0.6 times the
position of the ice line, (2) the distribution of planets' orbital
eccentricities is distinct from, and skewed toward lower values than the
observed distribution of (giant) exoplanet orbits, (3) inner systems of two
dominant planets (e.g., Earth and Venus) are not stable or do not form because
of the gravitational influence of the innermost icy planet. The planets
predicted by our model are unlikely to be detected by current Doppler
observations. Microlensing is currently sensitive to the most massive planets
found in our simulations. A scenario where up to 60% of stars host systems such
as those we simulate is consistent with all the available data. We predict
that, if this scenario holds, the NASA Kepler spacecraft will detect about 120
planets by two or more transits over the course of its 3.5 yr mission. Future
microlensing surveys will detect ~130 analogs over a 5 yr survey. Finally, the
Space Interferometry Mission (SIM-Lite) should be capable of detecting 96% of
the innermost icy planets over the course of a 5 yr mission.Comment: 17 pages, 16 figure
Planetary Transits Toward the Galactic Bulge
The primary difficulty with using transits to discover extrasolar planets is
the low probability a planet has of transiting its parent star. One way of
overcoming this difficulty is to search for transits in dense stellar fields,
such as the Galactic bulge. Here I estimate the number of planets that might be
detected from a monitoring campaign toward the bulge. A campaign lasting 10
nights on a 10 meter telescope (assuming 8 hours of observations per night and
a 5'x5' field of view) would detect about 100 planets with radius \rp=1.5
\rjup, or about 30 planets with \rp=1.0 \rjup, if the frequency and
distribution of planets in the bulge is similar to that in the solar
neighborhood. Most of these planets will be discovered around stars just below
the turn-off, i.e. slightly evolved G-dwarfs. Campaigns involving 1- or 4-m
class telescopes are unlikely to discover any planets, unless there exists a
substantial population of companions with \rp > 1.5 \rjup.Comment: 4 pages, 4 figures. Submitted to ApJ Letter
A biomechanical analysis of the heavy sprint-style sled pull and comparison with the back squat
This study compared the biomechanical characteristics of the heavy sprint-style sled pull and squat. Six experienced male strongman athletes performed sled pulls and squats at 70% of their 1RM squat. Significant kinematic and kinetic differences were observed between the sled pull start and squat at the start of the concentric phase and at maximum knee extension. The first stride of the heavy sled pull demonstrated significantly (
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