Coefficient of elastic yielding of sand backfill of dock-type lock chambers

1967 ◽  
Vol 1 (12) ◽  
pp. 1062-1066
Author(s):  
D. I. Mezhnev
Keyword(s):  
2010 ◽  
Vol 49 (10) ◽  
pp. 985-991 ◽  
Author(s):  
Xin Li ◽  
Shi-Qing Wang
Keyword(s):  

1960 ◽  
Vol 82 (2) ◽  
pp. 309-320 ◽  
Author(s):  
A. B. Jones

A completely general solution is obtained whereby the elastic compliances of a system of any number of ball and radial roller bearings under any system of loads can be determined. Elastic yielding of the shaft and supporting structure are considered as well as centrifugal and gyroscopic loading of the rolling elements under high-speed operation. The solution defines the loading and attitude of each rolling element in each bearing of the system as well as the displacement of each inner ring with respect to its outer ring. For ball bearings the precise location of the load paths in each raceway are found. Life estimates can be more accurately made since the fatigue effects can be evaluated over known paths in the raceways. The solution, which is accomplished numerically by iterative techniques, has been programmed for an IBM-704 digital computer.


2014 ◽  
Vol 47 (11) ◽  
pp. 3661-3671 ◽  
Author(s):  
Shiwang Cheng ◽  
Shi-Qing Wang

The modern investigation of the wandering of the Earth’s axis of rotation, considered as a physical problem relating to the actual non-rigid Earth, may be said to have been initiated in Lord Kelvin’s address to the Physical Section of the British Association in 1876. After referring to the scrutiny of the recorded observations of change of latitudes, conducted by Peters in 1841 and independently by Maxwell in 1851, in search of the regular Eulerian free period of 306 days which would belong to a rigid Earth, with negative results, he insisted that the irregular motions brought out in these analyses are not merely due to instrumental imperfections but represent true motions of the Pole, due to displacement of terrestrial material. For example, he estimates that existing shifts of material, of meteorological type, are competent to produce displacements of the axis of rotation ranging from ½ to 1/20 of a second of arc. A sudden shift of material on the Earth will not at once affect the axis of rotation, but will start it into motion round the altered axis of inertia, with a period of 306 days if the Earth were rigid, which will go on displacing the Pole until it is damped out by the frictional effects of the tidal motions thus originated. A radius of rotation of 1 second of arc would raise an ocean tide of the same period as the rotation, having as much as 11 cm. of maximum rise and fall. Thus the motion of the Pole is to be considered as continually renewed by meteorological and other displacements, as it is damped off by tidal and elastic friction; it was therefore, perhaps, not to be expected that it would show much periodicity, though the movements were eminently worthy of close investigation. Their nature was examined more closely by Newcomb at Kelvin’s request; but not much more had been done regarding their cause when Chandler announced that the records of changes of latitude did actually indicate a period of precession—of 427 days, however, instead of the Eulerian period of 306 days, which, if any, had previously been taken for granted. Soon after, in 1890, observations were organised systematically by the International Geodetic Union on the motion of Prof. Foerster, of Berlin; and already, in 1891, he was able to inform Lord Kelvin that a comparison of European observations with synchronous ones made at Honolulu gave direct proof of his conclusion of 1876 ( supra ), “ that irregular movements of the Earth’s axis to the extent of half a second may be produced by the temporary changes of sea level due to meteorological causes.” In the following year the synchronous observations had already indicated periodicity, apparently in about 385 days, considerably less than Chandler’s estimate, which, however, longer observation has since confirmed substantially. Lord Kelvin remarks in his next annual address as follows:—“ Newcomb, in a letter which I received from him last December, gave what seems to me undoubtedly the true explanation of this apparent discrepance from dynamical theory, attributing it to elastic yielding of the Earth as a whole. He added a suggestion, especially interesting to myself, that investigation of the periodic variations of latitude may prove to be the best means of determining approximately the rigidity of the Earth. As it is, we have now for the first time what seems to be a quite decisive demonstration of elastic yielding of the Earth as a whole, under the influence of a deforming force, whether of centrifugal force round a varying axis, as in the present case, or of tide-generating influences of the Sun and Moon, with reference to which I first raised the question of elastic yielding of the Earth’s material many years ago.” But “when we consider how much water falls on Europe and Asia during a month or two of rainy season, and how many weeks or months must pass before it gets to the sea, and where it has been in the interval, and what has become of the air from which it fell, we need not wonder” that the amplitudes of the polar wanderings “should often vary by 5 or 10 metres in the course of a few weeks or months.”


1938 ◽  
Vol 5 (1) ◽  
pp. A1-A6
Author(s):  
Lydik S. Jacobsen

Abstract During the last ten years numerous observations of vibrational periods of buildings have been made, especially by the Seismological Division of the United States Coast and Geodetic Survey in California. Even before the results of these observations were available it was recognized that the factors influencing the periods of buildings are many and involved, and that a rational approach to the problem must necessarily ignore a number of the factors. The debatable question has been, and perhaps still is: Which of the factors must not be ignored? If the discussion be restricted to apply to multistory buildings of relatively symmetrical plan, there is a temptation to consider the buildings cantilever beams planted in or on an elastic ground. However, a multistory building is not necessarily a slender structure. For this reason the degree to which flexural and shearing distortions of the cantilever beam representing the building assume importance for the period determinations is not obvious quantitatively. Similarly, the type of ground deformation or elastic yielding that must be considered varies with the slenderness of the building as well as with the type of foundation and ground. The present study attempts to show that a rational treatment of the problem becomes greatly involved and therefore impractical if too many factors have to be taken into account. Moreover, the study enables the investigator to form an intelligent estimate of the relative importance of the influence on the periods of the factors that he is forced to neglect.


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