Research on Stability of Crawler System for Deep Sea ROV

2009 ◽  
Author(s):  
Tomoya Inoue ◽  
Tokihiro Katsui ◽  
Hisataka Murakami ◽  
Junichiro Tahara
Keyword(s):  
Deep Sea ◽  
Extreme Case ◽  
Center Of Gravity ◽  
The Other ◽  
Water Tank ◽  
Fundamental Theory ◽  
Initial Investigation ◽  
Other Hand ◽  
Advantageous Effect ◽  
Stable Area

A deep sea ROV is desired to be light from the viewpoints of reducing a tension on an underwater cable and possessing the adequate movability by thrusters in water. On the other hand, when moving by a crawler system on the seabed, such a lightweight will influence on its movability characteristics. As an initial investigation experiments using an actual ROV were conducted in a water tank. And it was observed that the ROV ran in wheelie in some cases and almost fell down in extreme case in spite of the fact that it could run stably on land. In order to clarify the results fundamental theory of stability of the ROV in steady running is presented. The theory gives the discriminant chart of stable running for the combination of the center of gravity and the center of buoyancy. Experiments using a model were conducted to verify the theory. In order to increase the stable area and also to change meaningly the center of gravity, this paper proposes a method to virtually increase the weight and to change the center of gravity by using thrusters. And preliminary experiments were conducted to confirm its advantageous effect.

Crawler System for Deep Sea ROVs

2009 ◽  
Vol 43 (5) ◽  
pp. 97-104 ◽  
Author(s):  
Tomoya Inoue ◽  
Tokihiro Katsui ◽  
Hisataka Murakami ◽  
Ken Takagi
Keyword(s):  
Deep Sea ◽  
Center Of Gravity ◽  
Water Tank ◽  
Normal Type ◽  
Remotely Operated Vehicle ◽  
Sea Floor ◽  
System A ◽  
Stable Area

AbstractIn order to reduce tension on a cable and process movability, a deep sea remotely operated vehicle (ROV) is designed to reduce its weight. However, a lightweight ROV is apt to wheelie when running by means of a crawler system. To run stably in counterpoise, the combination of the center of gravity and the center of buoyancy should be in an adequate area called the “stable area,” which by theory can be obtained as corresponding to the weight and the buoyancy. The stable area becomes small as the weight is light. The combination of the center of gravity and the center of buoyancy is designed to be in the stable area. However, it is important for the ROV to run forward and backward, which results in changing the discrimination of the stable area. This sometimes causes the center of gravity and the center of buoyancy to be outside the stable area. Thus, it is advantageous to increase the weight only when running by crawler system and to change the center of gravity meaningfully. Furthermore, the flipper-type crawler system is advantageous when running on the sea floor with inclination or undulation. This paper proposes a method to virtually increase the weight and to change the center of gravity by using thrusters. This paper also describes the flipper-type crawler system that improves movability when running on the sea floor with inclination or undulation. Furthermore, we conducted preliminary experiments in a water tank using a small-size ROV having four thrusters and a crawler system, a normal-type crawler, and a flipper-type crawler system, to confirm the advantages.

The Viscosity and Structure Viscosity of Rubber Solutions and Emulsions

1956 ◽  
Vol 29 (3) ◽  
pp. 880-887 ◽  
Author(s):  
J. Schurz
Keyword(s):  
Colloidal Solution ◽  
Mutual Effect ◽  
Extreme Case ◽  
Frictional Resistance ◽  
The Other ◽  
Structural Viscosity ◽  
Uniform Size ◽  
Dispersed Particles ◽  
Other Hand ◽  
Particle Form

Abstract It is well known that the increase of viscosity of a colloidal solution over that of the pure solvent is produced by the frictional resistance to flow of the dispersed particles. The amount of this viscosity increase depends to a great extent on the shape of the particles. If these are spheres, only the ratio of the volume of the solute to the solvent is involved (Einstein's law), while in the other extreme case, namely with fiber molecules, the particle size plays such an important role, as is known, that one can calculate the particle weight of the dispersed phase from the viscosity (Staudinger's law, Mark-Houwink equation). But not only is the viscosity of a colloidal solution influenced by the particle form, but also its structural viscosity depends on it to a great degree. It is easy to understand this. For if the structure viscosity and, consequently, the decrease of viscosity with increasing velocity gradient, result from the fact that the hydrodynamic forces in the flowing solution, on the one hand, orient and distort the dispersed particles in the moving stream, and, on the other hand, oppose an eventual intermolecular mutual effect or aggregate formation of the particles, it is easily seen that the flow forces will be able to manifest these effects all the more readily and markedly the more extended and the stiffer the dispersed particles are. Thus it can be expected that, in general, in spherical particle suspensions no structural viscosity will appear, but that this will manifest itself the more strongly the more asymmetric the particles. With rubber it is easily possible to realize two extremely different dispersion forms. Rubber emulsions, as they exist in the various latexes, are typical definite spherical suspensions, with rather large particles of very uniform size. In rubber solutions, on the other hand, say in toluene or benzene, there is a macromolecular distribution. The dispersed particles are the individual kinky fiber molecules of the rubber, which are known to have a more or less elongated form. In fact these two types of rubber dispersions behave so differently that each of them can be called a typical representative of its class.

scholarly journals Report on the Gynecological Department of the Peter and Paul Hospital for 1896

2020 ◽  
Vol 11 (6) ◽  
pp. 653-681
Author(s):  
O. A. Dobbert
Keyword(s):  
Surgical Treatment ◽  
Present State ◽  
Center Of Gravity ◽  
The Other ◽  
Surgical Department ◽  
Other Hand ◽  
Chief Physician

The gynecological department that had existed for many years in the Petropavlovsk hospital until 1896 did not, according to modern concepts, have an independent character, since, for reasons not subject to close examination, it was impossible to operate in it. With a few exceptions, all patients who needed surgical aid were transferred to the surgical department. Thanks to the efforts and cares of the Chief Physician A.O. Metzler, since March 1896, the gynecological department has at its disposal an operation and instrumentation that leaves little to be desired and meets all the requirements of anti- and asepsis. It is obvious how essential the latter circumstance is for the separation. Of course, the name of such an operator as K.P.Dombrovsky), who was in charge of the surgical department, attracted at one time quite a few operational cases. On the other hand, however, many patients were frightened by the transfer to an unfamiliar department and another patient, who could be relieved of her suffering with the help of an operation, left the hospital without operational benefits. At present, the appearance of recovering from surgery makes it easier for this or that patient to undergo surgical treatment. I am far from thinking to bow before the operative polypharmacy, but still I cannot but admit the fact that, given the present state of our knowledge, the center of gravity should be shifted to the operative part of gynecology.

scholarly journals On a supposed Resemblance between the Marine Faunas of the Arctic and Antarctic Regions

1899 ◽  
Vol 22 ◽  
pp. 311-349 ◽  
Author(s):  
D'Arcy Wentworth Thompson
Keyword(s):  
Deep Sea ◽  
Continuous Distribution ◽  
Point Of View ◽  
The Other ◽  
The Arctic ◽  
Other Hand

The view that a peculiar likeness exists between the northern and southern extra-tropical faunas, and particularly between those of the Arctic and Antarctic regions, was suggested by Théel in discussing the remarkable deep-sea group of the Elasipoda, whose discovery we owe to the Challenger Expedition. A somewhat similar view is hinted at or referred to more than once in other Reports of the same Expedition. It was afterwards stated in an ampler way by Pfeffer (Versuch über die Erdgeschichtliche Entwickelung der jetzigen Verbreitungsverhältnisse unserer Thierwelt, 1891), and has of late been dealt with in great detail, and in relation to the antecedent causes that might have led to such a phenomenon, by Sir John Murray. On the other hand, Dr Ortmann, considering the hypothesis from the point of view of our knowledge of the distribution of Crustacea, has rejected it entirely (“Uber Bipolarität in der Verbreitung mariner Thiere,” Zool. Jahrb., 1896; cf. also “Marine Organismen und ihre Existenzbedingungen,” ib., 1897), and Dr Chun, dealing with the pelagic fauna (“Die Beziehungen zwischen dem arktischen und antarktischen Plankton,” Stuttgart, 1897), while showing how in truth a certain small number of forms are common to far northern and far southern seas, holds that the facts are sufficiently accounted for by the continuous distribution or gradual intermixture of forms in the depths of the intervening oceans under present conditions, without our needing to have recourse to an explanation of the phenomenon in the different conditions of a former age.

scholarly journals 2. On the Microscopic Characters of Volcanic Ashes and Cosmic Dust, and their Distribution in the Deep Sea Deposits

1884 ◽  
Vol 12 ◽  
pp. 474-495 ◽  
Author(s):  
John Murray ◽  
Mons. A. Renard ◽  
John Murray
Keyword(s):  
Deep Sea ◽  
Volcanic Eruptions ◽  
Cosmic Dust ◽  
The Other ◽  
Ceteris Paribus ◽  
Mineral Particles ◽  
Other Hand ◽  
Volcanic Ashes ◽  
Volcanic Debris ◽  
Mineral Constituents

In the Session of 1876, Mr John Murray communicated to this Society a paper on the distribution of volcanic debris over the floor of the ocean, and in it announced the discovery of cosmic dust in deep sea deposits. It was shown that at points, where neither the action of waves, rivers, or currents can transport the debris of continents, volcanic materials play the most important role in the formation of the mineral constituents of the deep sea deposits. It was pointed out that pumice, on account of its structure, was able-to float to great distances, but in time became waterlogged and sank to the bottom, there to decompose. On the other hand, incoherent volcanic matters, ejected in the form of lapilli, sand, and ashes, into the higher regions of the atmosphere, may, ceteris paribus, be conveyed, in consequence of their small dimensions and structure, to greater distances than other mineral particles derived from the continents. The possibility was also admitted that submarine volcanic eruptions might also contribute to the accumulation of those silicates and pyrogenous minerals and rocks, whose microscopic characters and distribution at the bottom of the sea we shall presently point out.

Proposed Restrictions on the Landing of Undersized Plaice, in the Light of the New Evidence

1896 ◽  
Vol 4 (2) ◽  
pp. 138-143
Author(s):  
J. T. Cunningham
Keyword(s):  
Deep Sea ◽  
The Other ◽  
Small Fish ◽  
Appreciable Difference ◽  
Size Limit ◽  
Dutch Coast ◽  
Other Hand ◽  
Parliamentary Committee ◽  
The One ◽  
New Evidence

Before the Parliamentary Committee, which conducted an inquiry in 1893, the trawling industry of Lowestoft, as represented by Mr. J. W. Hame, strongly opposed any restrictions being enforced as to the size of fish landed. One of the reasons given was that restriction was unnecessary, because small fish, especially plaice, were not landed at that port. Mr. Hame told the Committee that the day before he gave his evidence, namely, on May 10th, he turned out two boxes of plaice caught towards the Dutch coast, perhaps from 30 to 40 miles off that coast. He said that one box contained 110 fish, the smallest 12 in. long, and the other contained 90 fish, the smallest 13 in. long. These statements are quite at variance with my observations made at Lowestoft, during September and October this year, and I cannot help thinking that Mr. Hame was mistaken as to the grounds from which the fish came, or else was not sufficiently accurate in his numbers and measurements. The facts show that, on the one hand, a size-limit of 8 in. for plaice, as proposed by the Parliamentary Committee, would make no appreciable difference to the deep-sea trawling industry at Lowestoft, and, on the other hand, that higher limits, such as that which was proposed by Mr. Holt for the protection of the German grounds, would affect that port very seriously.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

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