Feasibility study of a discrete bearing/roller drive rotary joint for the space station

The most critical mechanism on board the proposed space station is the continously rotating joint which must accurately align the solar power units with the sun during earth orbit. The feasibility of a multiple, discrete bearing supported joint driven by a self-loading, pinch drive actuator was investigated for this application. This concept appears to offer greater protection against catastrophic jamming, less sensitivity to adverse thermal gradients, greater accessibility to inorbit servicing or replacement and greater adaptability to very large (5 m) truss members than to more conventional continuous support bearing/gear reducer joints. Analytical trade studies performed herein establish that a discrete cam roller bearing support system having eight hangers around a continuous ring would provide sufficient radial and bending stiffness to prevent any degradation in the fundamental frequencies of the solar wing structure. Furthermore, it appears that the pinch roller drive mechanism can be readily sized to meet or exceed system performance and service life requirements. Wear life estimates based on experimental data for a steel roller coated with an advanced polyimide film show a continuous service life more than two orders of magnitude greater than required for this application

Foraging behavior and Doppler shift compensation in echolocating hipposiderid bats, I-Iipposideros bicolor and I-Iipposideros speoris

1. Two hipposiderid bats,H. bicolor andH. speoris, were observed in their natural foraging areas in Madurai (South India). Both species hunt close together near the foliage of trees and bushes but they differ in fine structure of preferred hunting space:H. bicolor hunts within the foliage, especially whenH. speoris is active at the same time, whereasH. speoris never flies in dense vegetation but rather in the more open area (Fig. 1, Table 1). 2. Both species emit CF/FM-sounds containing only one harmonic component in almost all echolocation situations. The CF-parts of CF/FM-sounds are species specific within a band of 127–138 kHz forH. speoris and 147–159 kHz forH. bicolor (Tables 2 and 3). 3. H. speoris additionally uses a complex harmonic sound during obstacle avoidance and during laboratory tests for Doppler shift compensation.H. bicolor consistently emits CF/FM-sounds in these same situations (Fig. 2). 4. Both hipposiderid bats respond to Doppler shifts in the returning echoes by lowering the frequency of the emitted sounds (Fig. 3). However, Doppler compensations are incomplete as the emitted frequencies are decreased by only 55% and 56% (mean values) of the full frequency shifts byH. speoris andH, bicolor, respectively. 5. The differences in Doppler shift compensation, echolocating and hunting behavior suggest thatH. speoris is less specialized on echolocation with CF/FM-sounds thanH. bicolor

Inelastic collisions in an exactly solvable two-mode Bose-Einstein Condensate

Inelastic collisions occur in Bose-Einstein condensates, in some cases, producing particle loss in the system. Nevertheless, these processes have not been studied in the case when particles do not escape the trap. We show that such inelastic processes are relevant in quantum properties of the system such as the evolution of the relative population, the self trapping effect and the probability distribution of particles. Moreover, including inelastic terms in the model of the two-mode condensate allows for an exact analytical solution. Using this solution, we show that collisions favor the generation of entanglement between the modes of the condensate as long as the collision rate does not exceed the natural frequency of the system

Called to Service and to Seminary

How does it happen? On assignment day the whole world spread out before him… entering the ministry … his own group of people to shepherd … the heady challenge of a world needing both the courage of a prophet and the resounding proclamation of a gospel … the continuity of the holy Christian church. He was about to step into the procession of the Te Deum. His wife\u27s hand squeezed his as his name was called. Not too many years later late at night he sits wondering. It hasn\u27t turned out as he had dreamed. The opposition was more insidious, the apathy more deadening. Strangely, as time passed he had wondered more and more about himself - his own skills, his approaches. Maybe he just doesn\u27t have it; perhaps the way the ministry is set up is all wrong. Maybe he should get out now while he is still relatively young. The situation seems intolerable. God, what had happened

The Effects of Urbanization on the Function of the Church

The interest in this paper will not be the causes for the rise of urbanism or a study of the social ecology of the city. The emphasis will be on the social relationships in the city. We will ask the question of how these influences in urban areas have affected the function of the church in witnessing

\u27Your Job, Mr. President ... .

Good humor and a certain salty Lutheran irreverence are necessary on the day of a presidential inauguration to make sure we don\u27t believe every exaggeration spoken in the excitement of the occasion. You may remember the inauguration of a university president some years on the first anniversary of his inauguration ago. After two days of festivities and speeches suggesting that the fate of half of Western culture revolved about the decisions that would be made by the new president, a friend put his hand on his shoulder and said, \u27Look, George, forget all that stuff. You have three main jobs: to provide parking for the faculty, football for the alumni, and sex for the students

Labor, Industry, and the Church

The church stood amazed before the rising form of the industrial giant. Its size was frightening enough, but its two heads of unionism and management struck terror into her heart. The church felt she should say something to the monster. But then what could she say? It certainly didn\u27t look like a membership prospect. And so the church pretended she didn\u27t see it. But the church\u27s heart continued to pound. And way down deep she felt guilty. She had a message - even for such two-headed giants. And she should be speaking

Homiletics: Outlines on Synodical Conference Gospels

Outlines on Synodical Conference Gospel