3,945 research outputs found
Aeration Effects on Impact: Drop Test of a Flat Plate
Verbatim reproduction or republication of the papers or articles or part of the articles (e.g., figures or tables) by their authors, after the publication or presentation at the ISOPE meetings and journal, is permitted by the International Society of Offshore and Polar Engineers (ISOPE), provided the full credit is given to the authors, to the publisher, The International Society of Offshore and Polar Engineers (ISOPE), and to the Conference, Symposium or Journal - more specifically not to remove the copyright imprint on page 1 of the paper. The permission does not extend to copying for resale and to re-copyrighting the whole or part of the papers. Posting on your organization's website of the paper(s) you specified is allowed only where only your organization's employees including the students can view free of charge the paper authored or co-authored by your organization's employees, and www.isope.org is provided for the paper(s) in the ISOPE proceedings or journals. Regards, Prof. Jin S Chung Executive Director isope, 495 North Whisman Road, Suite 300 Mountain View, California 94043-5711, USA T 1-650-254-1871; F 1-650-254-2038; [email protected] [email protected], www.isope.org www.deepoceanmining.orgAeration effects on impact have been investigated by dropping a flat plate onto the water surface, in which the water is aerated to various degrees. An experimental study has been carried out in the newly commissioned Ocean Basin at Plymouth University’s COAST Lab. The falling block comprises a rigid impact plate connected to two driver plates and its total mass can be varied between 32 kg and 52 kg. The impact plate is 0.25m long, 0.25 m wide and 0.012 m high. The impact velocity is varied between 4 m/s and 7 m/s. Preliminary results of the impact tests are presented here. Visualised results show that there are significant differences between jet formation after impact of the plate in pure water and in aerated water. There is significant reduction of the maximum pressures from those measured in pure water to those measured in aerated water
Methodology for tidal turbine representation in ocean circulation model
The present method proposes the use and adaptation of ocean circulation models as an assessment tool framework for tidal current turbine (TCT) array layout optimization. By adapting both momentum and turbulence transport equations of an existing model, the present TCT representation method is proposed to extend the actuator disc concept to 3-D large-scale ocean circulation models. Through the reproduction of experimental flume tests and grid dependency tests, this method has shown its numerical coherence as well as its ability to simulate accurately both momentum and turbulent turbine-induced perturbations in both near and far wakes in a relatively short period of computation time. Consequently the present TCT representation method is a very promising basis for the development of a TCT array layout optimization tool
Absence of magnetic long range order in YCrSbO: bond-disorder induced magnetic frustration in a ferromagnetic pyrochlore
The consequences of nonmagnetic-ion dilution for the pyrochlore family
Y()O ( = magnetic ion, = nonmagnetic
ion) have been investigated. As a first step, we experimentally examine the
magnetic properties of YCrSbO ( = 0.5), in which the magnetic
sites (Cr) are percolative. Although the effective Cr-Cr spin exchange
is ferromagnetic, as evidenced by a positive Curie-Weiss temperature,
= 20.1(6) K, our high-resolution neutron powder
diffraction measurements detect no sign of magnetic long range order down to 2
K. In order to understand our observations, we performed numerical simulations
to study the bond-disorder introduced by the ionic size mismatch between
and . Based on these simulations, bond-disorder ( 0.23)
percolates well ahead of site-disorder ( 0.61). This model
successfully reproduces the critical region (0.2 < < 0.25) for the N\'eel
to spin glass phase transition in Zn(CrGa)O, where
the Cr/Ga-sublattice forms the same corner-sharing tetrahedral network as the
-sublattice in Y()O, and the rapid drop in
magnetically ordered moment in the N\'eel phase [Lee , Phys. Rev. B
77, 014405 (2008)]. Our study stresses the nonnegligible role of bond-disorder
on magnetic frustration, even in ferromagnets
The effectiveness of dieldrin for control of the Argentine ant in Western Australia
The results of three experiments to compare insecticides for the eradication of Argentine ants are reported. The areas used for the tests were typical household allotments in Shenton Park, a suburb of Perth, Western Australia. The methods of application of sprays and evaluation of results were the same as described in a previous paper. (Forte & Greaves 1953.
New insecticides for the control of the Argentine ant in Western Australia
The Argentine Ant (Iridomyrmex humilis Mayr), has been the subject of much investigation in Western Australia. Jenkins (1943), Jenkins and Forte (1946, 1951), Jenkins (1948) and Forte (1949) have reported results of extensive work on the control of this pest. The results of the investigations have shown that effective control can be obtained by the use of DDT sprays but that large scale eradication was not possible with DDT
Bulletin No. 274 - Influence of Rotation and Manure on the Nitrogen, Phosphorus, and Carbon of the Soil
All agricultural plants require carbon, hydrogen, oxygen, nitrogen, calcium, potassium, magnesium, sulfur, phosphorus, iron, and probably traces of other elements for their normal growth and fruition. The growth of farm crops is dependent upon an available supply of these elements, and the extent of growth is governed by the one present and available in least quantity in proportion to the plant\u27s needs. Of the essential elements, all plants secure two (carbon and oxygen) from the air, one (hydrogen) from the water, and the others from the soil. Most soils contain sufficient plant nutrients for normal plant production, with the exception of nitrogen, phosphorus, and potassium. These elements are used by the plants from the soil in the largest quantities and are generally the plant nutrients governing the productivity of a soil. In addition, the organic matter of the soil is of prime importance, for it is the matrix which holds the nitrogen and governs the structure and water-holding capacity of the soil. Probably most Utah soils contain sufficient potassium; consequently, the problem of Utah soil fertility resolves itself into maintaining an optimum concentration of nitrogen, phosphorus, and organic material in the soil. Therefore, this work represents a study of the influence of manure and crop rotation on the nitrogen, phosphorus, and carbon in the soil
Bulletin No. 310 - The Influence of Cropping on the Nitrogen, Phosphorus and Organic Matter of the Soil Under Irrigation Farming
Most soils contain sufficient nutrients for normal plant growth, with the exception of nitrogen, phosphorus and potassium. These elements are used by plants in the largest quantities and the amounts of these in the soil govern its productivity. Soil organic matter is of prime importance for it is the matrix which holds the nitrogen and modifies the structure, temperature, and water-holding capacity of the soil. The organic matter is the very life of the soil, for it is in and on it that bacteria work and by so doing determine the kind and speed of reactions which occur. It is the bacterial activities in the soil that determine the available plant food. Probably most Utah soils contain sufficient potassium, consequently the problem of Utah soil fertility resolves itself into maintaining an optimum concentration of nitrogen, phosphorus, and organic matter. The present work represents a study of the phosphorus, nitrogen, and organic matter in the soil and the speed with which they are being removed by plants, erosion and leaching
Bulletin No. 163 - Composition of the Irrigation Waters of Utah
Analytical work which has so far been published on the composition of the irrigation waters of the Intermountain Region indicates a wide variation in their composition. Some are exceptionally pure, being nearly free from alkali, and may be used without fear of injury to soils; others contain larger quantities of alkali and must be used with care; still others are so heavily charged with soluble salts that they must be used with extreme caution, otherwise the growing crop will be injured and in time the soil rendered unfit for agricultural purposes. The land then must be either reclaimed or abandoned, either of which will entail an enormous expense to the landowner and indirectly to the State. Much of this unnecessary loss can be prevented if definite and complete information be available on the composition of the irrigation waters
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