Load deflection characteristics of inflated structures

A single, closed form relationship to relate load to the deformed dimensions of the horizontal torus was developed. Wall elasticity was included in the analysis, and special care was taken to predict the final footprint area of the loaded structure. The test fixture utilized is shown. The tori used for the bulk of the testing were rubber inner tubes for a 32 and 160 pneumatic tire. The inner tube being tested was plumbed, to a mercury-filled manometer, which had a 50 inch measurement capacity, by use of a special adapter. The adapter fit over the valve stem and allowed air to be added from a shop-air source and to be bled through the standard valve mechanism. In this fashion, tests requiring the maintenance of a constant indication of air pressure could be run with little difficulty

A Geometrical Method of Decoupling

The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries - like midplane symmetrie - are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane and (under certain circumstances) the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as for instance the method of Teng and Edwards. In a preceeding paper it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all thinkable cases. Hence a systematic derivation of a more general treatment seemed advisable. In a second paper the author suggested the use of real Dirac matrices as basic tools to coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. It is shown that this algebraic decoupling is closely related to a geometric "decoupling" by the orthogonalization of the vectors $\vec E$, $\vec B$ and $\vec P$, that were introduced with the so-called "electromechanical equivalence". We present a structure-preserving block-diagonalization of symplectic or Hamiltonian matrices, respectively. When used iteratively, the decoupling algorithm can also be applied to n-dimensional systems and requires ${\cal O}(n^2)$ iterations to converge to a given precision.Comment: 13 pages, 1 figur

Coincident measurements of PMSE and NLC above ALOMAR (69° N, 16° E) by radar and lidar from 1999-2008

Polar Mesosphere Summer Echoes (PMSE) and Noctilucent Clouds (NLC) have been routinely measured at the ALOMAR research facility in Northern Norway (69° N, 16° E) by lidar and radar, respectively. 2900 h of lidar measurements by the ALOMAR Rayleigh/Mie/Raman lidar were combined with almost 18 000 h of radar measurements by the ALWIN VHF radar, all taken during the years 1999 to 2008, to study simultaneous and common-volume observations of both phenomena. PMSE and NLC are known from both theory and observations to be positively linked. We quantify the occurrences of PMSE and/or NLC and relations in altitude, especially with respect to the lower layer boundaries. The PMSE occurrence rate is with 75.3% considerably higher than the NLC occurrence rate of 19.5%. For overlapping PMSE and NLC observations, we confirm the coincidence of the lower boundaries and find a standard deviation of 1.26 km, hinting at very fast sublimation rates. However, 10.1% of all NLC measurements occur without accompanying PMSE. Comparison of occurrence rates with solar zenith angle reveals that NLC without PMSE mostly occur around midnight indicating that the ice particles were not detected by the radar due to the reduced electron density

Activity recorded from the statocyst nerve of Pleurobranchaea californica during rotation and at different tilts

1. 1. The statocysts of Pleurobranchaea californica lie lateral to the pedal ganglia. The thirteen receptor cells communicate with the cerebro-pleural ganglion via the thirteen axons of the statocyst nerve.2. 2. Each unit in the statocyst nerve of Pleurobranchaea responds over a limited range of positions.3. 3. Receptor adaptation is slow. Each position in the active range of a unit is coded by the same steady-state firing rate. Initial frequencies upon reaching a particular position differ, depending upon the direction of approach.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34013/1/0000288.pd

Facilitation of excitatory post-synaptic potentials in the giant cell in the left pleural ganglion of Aplysia californica

1. 1. Heterosynaptic facilitation (HSF) was found to begin to develop after a latency of between 1900 and 2000 msec after which the amplitude of HSF increased as a function of the prime test interval.2. 2. Changes in the amplitude of the HSF could last as long as 42 hr.3. 3. The HSF in the pleural giant cell was of greater amplitude than that in the abdominal giant cell.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34181/1/0000470.pd

Time course of repetitive heterosynaptic facilitation in Aplysia californica

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33356/1/0000754.pd

Behavioral responses to linear accelerations in blind goldfish

Blind goldfish were subjected to linear accelerations on a motor car and on a parallel swing. Moyements of the fish in a tank during the accelerations were recorded with a movie camera. During the horizontal acceleration, the fish aligns his longitudinal axis in a plane perpendicular to the direction of an apparent gravity with the fish's back pointing away from the direction of this apparent gravity vector. This is similar to the manner in which the fish usually aligns himself horizontally in response to the vertically downward terrestrial gravity and can therefore be termed ‘gravity reference response’. It is concluded that blind goldfish cannot distinguish between otolith displacements caused by passive tilts and equivalent otolith displacements caused by moderate inertial forces during rectilinear acceleration. With a horizontal jerk of higher magnitude, two additional responses can occur: horizontal 180° turns following tailward jerks and straight forward darting following noseward jerks.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43351/1/11084_2004_Article_BF00924211.pd

Radar Observation of Extreme Vertical Drafts in the Polar Summer Mesosphere

The polar summer mesosphere is the Earth's coldest region, allowing the formation of mesospheric ice clouds. These ice clouds produce strong polar mesospheric summer echoes (PMSE) that are used as tracers of mesospheric dynamics. Here, we report the first observations of extreme vertical drafts (+/-50 ms [hoch]-1) in the mesosphere obtained from PMSE, characterized by velocities more than five standard deviations larger than the observed vertical wind variability. Using aperture synthesis radar imaging, the observed PMSE morphology resembles a solitary wave in a varicose mode, narrow along propagation (3–4 km) and elongated (>10 km) transverse to propagation direction, with a relatively large vertical extent (~13 km). These spatial features are similar to previously observed mesospheric bores, but we observe only one crest with much larger vertical extent and higher vertical velocities

The gravity reference response, the rotation sensation, and other illusory sensations experienced in aircraft and space flight

An analysis of the gravitational and inertial forces which act during aircraft flight upon the vestibular systems of the aircraft occupants reveals that in the absence of a visual horizon, certain illusory sensations are predictable for various acceleration environments. Horizontal forward applied acceleration results in a climbing (backward tilting) sensation; conversely, horizontal rearward applied acceleration results in a diving (forward tilting) sensation. During any attempt to achieve weightlessness in aircraft parabolic flight, special care has to be taken to avoid unintended longitudinal ( x -axis) accelerations. Recent flight tests established that the ‘rotation sensation’ (Dzendolet, 1971; Gerathewohl, 1956) during entry into parabolic flight can be attributed to the existence of unintended longitudinal accelerations. However, the ‘inversion illusion’ (Graybiel and Kellogg, 1966) felt by some human subjects at 0 g seems to be different from the rotation sensation and could be caused by the diminished pressure forces of the otoliths on the maculae. The ‘inversion illusion’ of man correlates well with the blind fish diving behavior observed during aircraft parabolic flight (von Baumgarten et al. , 1969, 1972). It is suggested that the fish low g diving response and the human inversion illusion are due to the substitution of a predominately shearing force of low magnitude as a vestibular reference in place of a normal, predominately pressure force. This hypothesis indicates that vestibular senses alone cannot provide meaningful postural orientation to simulated or actual gravity of a magnitude below that of Earth's gravity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43353/1/11084_2004_Article_BF00930350.pd