The determination of optimum array lengths based on signal coherence in deep and shallow water.

1996 ◽  
Vol 99 (4) ◽  
pp. 2571-2574
Author(s):  
William M. Carey ◽  
Peter Cable
Keyword(s):  
Shallow Water

Determination of the added masses and damping coefficients during coupled motions of two ships in shallow water parallel to the vertical wall

2021 ◽  
pp. 16-25
Author(s):  
В.Ю. Семенова ◽  
К.И. Баканов
Keyword(s):  
Shallow Water ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Hydrodynamic Coefficients ◽  
Damping Coefficients ◽  
Added Masses ◽  
Joint Motions ◽  
National Practice ◽  
Simultaneous Influence

В статье рассматривается определение коэффициентов демпфирования и присоединенных масс, возникающих при совместной качке двух судов в условиях мелководья параллельно вертикальной стенке на основании решения трехмерной потенциальной задачи. Определение гидродинамических коэффициентов осуществляется на основании методов интегральных уравнений и зеркальных отображений. Представленное решение в отечественной практике является новым. В статье приводятся результаты расчетов коэффициентов присоединенных масс и демпфирования, возникающих при качке двух одинаковых судов, расположенных лагом к волнению и параллельно вертикальной стенке в зависимости от изменения расстояний как между судами, так и между судами и вертикальной стенкой. Проводится исследование влияния различных фарватеров на величины гидродинамических коэффициентов, а именно: мелководного фарватера, мелководного фарватера с вертикальной стенкой, мелководного фарватера со вторым параллельно качающимся судном и мелководного фарватера с вертикальной стенкой и вторым судном. Таким образом, в работе учитывается одновременное влияния мелководья, вертикальной стенки и второго судна. Показано увеличение значений коэффициентов присоединенных масс и демпфирования при уменьшении расстояний между судами и между судами и вертикальной стенкой. Также показано значительное совместное влияние вертикальной стенки и второго судна на коэффициенты присоединенных масс и демпфирования по сравнению с другими видами стесненных фарватеров. The article discusses the determination of damping coefficients and added masses arising from the joint motions of two ships in shallow water conditions parallel to the vertical wall based on the solution of a three-dimensional potential problem. Determination of hydrodynamic coefficients is carried out on the basis of the methods of integral equations and mirror images. The solution presented in the national practice is new The article presents the results of calculating the coefficients of added masses and damping arising from the motions of two identical ships located lagged to the sea and parallel to the vertical wall, depending on the change in the distances between the ships and between the ships and the vertical wall. A study is being made of the influence of various waterways on the values ​​of hydrodynamic coefficients, namely: a shallow waterway, a shallow waterway with a vertical wall, a shallow waterway with a second parallel oscillating ship and a shallow waterway with a vertical wall and a second ship. Thus, the work takes into account the simultaneous influence of shallow water, vertical wall and the second ship. An increase in the values of the coefficients of added masses and damping with a decrease in the distances between ships and between ships and the vertical wall is shown. It also shows a significant combined effect of the vertical wall and the second ship on the added mass and damping coefficients in comparison with other types of constrained waterways.

scholarly journals IV. On the structure and relations of the alcyonarian heliopora cærulea, with some account of anatomy of a species of sarcophyton, notes on the structure of species of the genera millepora, pocillopora, and stylaster, and remarks on the affinities of certain palœozoic corals

1876 ◽  
Vol 166 ◽  
pp. 91-129 ◽  
Keyword(s):  
Shallow Water ◽  
Deep Sea ◽  
Living State ◽  
The Subject ◽  
Deep Sea Corals ◽  
In The Beginning

Having undertaken the examination of the Deep-sea Corals dredged by the ‘Challenger’ during her voyage, my attention was naturally directed to the study of the structure of corals generally. The Milleporidse, both because of their peculiar tabulate structure and relations to fossil forms, and because of Prof. A gassiz’s well-known determination of them as Hydroids and not Actinozoa, seemed to offer the most interesting field for in­vestigation ; and I accordingly commenced the examination of their structure very early in the cruise of H. M. S. ‘Challenger’ in April 1873, at Bermuda, where Millepora alcicornis occurs in great profusion. I made a number of preparations and made out some points in the anatomy of this species, but found the subject to be so difficult that I put the matter aside to be further examined on reaching England. In the beginning of 1875, however, I obtained speci­mens of Heliopora caerulea in the living state at Zamboangan, and on examining these found to my astonishment that Heliopora was an Alcyonarian. I therefore during subsequent voyages made as complete an examination as possible of this species, and examined for comparison with it the structure of another Alcyonarian, a species of Sarcophyton dredged in shallow water amongst the reefs of the Admiralty Islands. I examined further the structure of a species of Millepora obtained at Zamboangan ; and I also examined a Pocillopora found at the same locality, and a species of Stylaster dredged in 500 fathoms off the Meangis Islands. The results form the substance of the present paper.

Determination of Wave Angle in Shallow Water

1986 ◽  
Vol 112 (1) ◽  
pp. 129-139 ◽  
Author(s):  
Douglas J. Sherman ◽  
Brian Greenwood
Keyword(s):  
Shallow Water ◽  
Wave Angle

scholarly journals Water Phase Inclination Theory for Hydraulic Conductivity Determination of Vadose Zones in Shallow Water Table Systems

2021 ◽  
Vol 54 (2B) ◽  
pp. 85-100
Author(s):  
Arkan Radi Ali
Keyword(s):  
Hydraulic Conductivity ◽  
Shallow Water ◽  
Linear Relationship ◽  
Water Table ◽  
Correlation Factor ◽  
Water Phase ◽  
Shallow Water Table ◽  
Allowable Limit ◽  
Undisturbed Soil

Water Phase Inclination is an innovative theory for hydraulic conductivity and determination of vadose zone overlying shallow water table systems. It was originated and analytically derived from Darcy's Law and based on some physio-mechanical properties of soil. Al-Musayab area of 176 Km2 at Mesopotamian region, mid-Iraq was undertaken as a case study. It consists of unconsolidated quaternary deposits and is usually finer-grained than the underlying pebbly sandstone with Mediterranean weather. The Experimental part was divided into field tests which include double ring infiltrometer tests, water table depth measurements and sampling of 32 undisturbed soil samples of surface layers scattered over the study area Whereas lab tests include; the falling and constant head permeability, grain size distribution (sieve and hydrometer analysis), soil specific gravity, direct shear tests and the measuring of Water Phase Inclinations. Angle \emptyset a glassy infiltration box is an experimental device that was manufactured to measure the Water Phase Inclination angle and aquifer simulation. It is found a generalized linear relationship between  and the angle of internal friction which is valid for   23.37 with correlation factor R² = 0.99 and both angles depend on soil texture. The k values estimated by WPI theory and that measured by traditional techniques offer a linear relationship with acceptable Root Mean Square Error equals 0.0642 < 0.1 the max allowable limit and correlation factor R² = 0.96, pointing out to the reliability and stability of the Water Phase Inclination results.

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