scholarly journals 1612 MHz observations of southern IRAS sources

1987 ◽  
Vol 122 ◽  
pp. 215-216
Author(s):  
M. E. Dollery ◽  
M. J. Gaylard ◽  
R. J. Cohen

Eight of thirty-four previously unobserved IRAS sources were found to be relatively strong 1612 MHz OH emitters. Five of these emit at 1667 MHz. Of the eight half are high velocity range, population I type stars, the other half are low velocity range, population II type stars. The pump efficiencies are in the range 0.018 ≤ e ≤ 0.163.

It is evident from the previous papers that we know a good deal about the initiation of explosion in solids. On the other hand, the processes which take place during the growth of explosion from a nucleus of decomposition are not all clearly understood. We can summarize the different stages which can occur between initiation of reaction and detonation in the following way. (1) Initiation of reaction in the solid by a suitable source of energy, e. g. hes light, shock, ionizing radiation, etc. (2) The growth of reaction from this region of decomposition into an acceleration burning. This can attain speeds up to several hundred metres per second. (3) A sharp transition from burning to low-velocity detonation. (4) Propagation of low-velocity detonation with a velocity in the region 1000 m/s. (5) Propagation of high-velocity detonation at a velocity of about 5000 m/s higher.


2021 ◽  
pp. 004051752110592
Author(s):  
Na Sun ◽  
Na Sun

The motion of floating fibers in the drafting zone has a significant effect on the sliver quality after drafting. In this study, the distribution of the accelerated point of floating fibers in the drafting area was simulated based on the distribution of fibers and frictional forces during the drafting process. The simulated results denoted that the acceleration distribution of the floating fibers was more concentrated and closer to the front roller as the drafting ratio increases. The distributions of accelerated points of the floating fibers became more and more decentralized and further away from the front roller as the gauge length grew when the other parameters remained constant. In the simulation, the frictional forces of the other floating fibers moving at high velocity and low velocity and the actual contact relationships of fibers in the drafting zone were taken into consideration. Moreover, whether the fiber lengths are identical or not, the simulated accelerated-point distributions of the floating fibers were demonstrated to conform more to the actual values compared to other models. Hence, the developed model can offer effective reference from the point of view of the distribution of accelerated points in order to realize the simulation of roller drafting.


Perception ◽  
1994 ◽  
Vol 23 (10) ◽  
pp. 1171-1179 ◽  
Author(s):  
Wim A van de Grind ◽  
Frans A J Verstraten ◽  
Karin M Zwamborn

Moving random-pixel arrays (RPAs) were used to study the movement aftereffect (MAE) for translational texture motion and to quantify the contribution of RPA-sensitive motion sensors to the MAE as a function of eccentricity. Size-scaled patterns were used to make a fair comparison across eccentricities. At the upper end of the velocity range it was found, for all eccentricities, that motion sensors tuned to velocities exceeding about 10–20 deg s−1 do not contribute to the translational MAE, even though they do contribute to motion perception. As a consequence the subpopulation of local motion sensors that contributes to the MAE shrinks with eccentricity, because there are fewer low-velocity-tuned and more high-velocity-tuned motion sensors for increasing eccentricity. Thus there is a quantitative, but not a qualitative, difference between the MAEs generated at different eccentricities.


2021 ◽  
pp. 1-7
Author(s):  
Mercè Torra ◽  
Eduard Pujol ◽  
Anna Maiques ◽  
Salvador Quintana ◽  
Roser Garreta ◽  
...  

BACKGROUND: The difference between isokinetic eccentric to concentric strength ratios at high and low velocities (DEC) is a powerful tool for identifying submaximal effort in other muscle groups but its efficiency in terms of the wrist extensors (WE) and flexors (WF) isokinetic effort has hitherto not been studied. OBJECTIVE: The objective of the present study is to examine the usefulness of the DEC for identifying suboptimal wrist extensor and flexor isokinetic efforts. METHODS: Twenty healthy male volunteers aged 20–40 years (28.5 ± 3.2) were recruited. Participants were instructed to exert maximal and feigned efforts, using a range of motion of 20∘ in concentric (C) and eccentric (E) WE and WF modes at two velocities: 10 and 40∘/s. E/C ratios (E/CR) where then calculated and finally DEC by subtracting low velocity E/CR from high velocity ones. RESULTS: Feigned maximal effort DEC values were significantly higher than their maximal effort counterparts, both for WF and WE. For both actions, a DEC cutoff level to detect submaximal effort could be defined. The sensitivity of the DEC was 71.43% and 62.5% for WE ad WF respectively. The specificity was 100% in both cases. CONCLUSION: The DEC may be a valuable parameter for detecting feigned maximal WF and WE isokinetic effort in healthy adults.


Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 122
Author(s):  
Irina Medved ◽  
Elena Bataleva ◽  
Michael Buslov

This paper presents new results of detailed seismic tomography (ST) on the deep structure beneath the Middle Tien Shan to a depth of 60 km. For a better understanding of the detected heterogeneities, the obtained velocity models were compared with the results of magnetotelluric sounding (MTS) along the Kekemeren and Naryn profiles, running parallel to the 74 and 76 meridians, respectively. We found that in the study region the velocity characteristics and geoelectric properties correlate with each other. The high-velocity high-resistivity anomalies correspond to the parts of the Tarim and Kazakhstan-Junggar plates submerged under the Tien Shan. We revealed that the structure of the Middle Tien Shan crust is conditioned by the presence of the Central Tien Shan microcontinent. It manifests itself as two anomalies lying one below the other: the lower low-velocity low-resistivity anomaly, and the upper high-velocity high-resistivity anomaly. The fault zones, limiting the Central Tien Shan microcontinent, appear as low-velocity low-resistivity anomalies. The obtained features indicate the fluid saturation of the fault zones. According to the revealed features of the Central Tien Shan geological structure, it is assumed that the lower-crustal low-velocity layer can play a significant role in the delamination of the mantle part of the submerged plates.


2018 ◽  
Vol 53 (4) ◽  
pp. 535-546 ◽  
Author(s):  
M Altaf ◽  
S Singh ◽  
VV Bhanu Prasad ◽  
Manish Patel

The compressive strength of C/SiC composite at different strain rates, off-axis orientations and after high-velocity impact was studied. The compressive strength was found to be 137 ± 23, 130 ± 46 and 162 ± 33 MPa at a strain rate of 3.3 × 10−5, 3.3 × 10−3, 3.3 × 10−3 s−1, respectively. On the other hand, the compressive strength was found to be 130 ± 46, 99 ± 23 and 87 ± 9 MPa for 0°/90°, 30°/60° and 45°/45° fibre orientations to loading direction, respectively. After high-velocity impact, the residual compressive strength of C/SiC composite was found to be 58 ± 26, 44 ± 18 and 36 ± 3.5 MPa after impact with 100, 150 and 190 m/s, respectively. The formation of kink bands in fibre bundles was found to be dominant micro-mechanism for compressive failure of C/SiC composite for 0°/90° orientation. On the other hand, delamination and the fibre bundles rotation were found to be the dominant mechanism for off-axis failure of composite.


In this Discussion we are concerned with the mechanism by which an explosion can be initiated in a solid or liquid and can grow to a high-velocity detonation. It is convenient to divide the process into four stages: (1) initiation in some localized region; (2) the growth of the explosion; (3) a transition stage or low-velocity detonation which finally passes over to (4) a high-velocity stable detonation. Stage (4) has been dealt with at an earlier Discussion in this Society led by Sir William Penney (1950). Here we propose to concentrate our attention on (1), (2) and (3). We shall begin with the initiation process and then later in the Discussion go on to consider the growth to detonation.


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