The Water Depth Effect on Ship Pressure Distribution and Surface Wave

2012 ◽  
Vol 166-169 ◽  
pp. 3071-3074
Author(s):  
Tao Miao ◽  
Zhi Hong Zhang ◽  
Chong Wang ◽  
Ju Bin Liu ◽  
Jian Nong Gu
Keyword(s):  
Pressure Distribution ◽  
Steady Motion ◽  
Finite Depth ◽  
Wave Pattern ◽  
Integral Function ◽  
Kelvin Wave ◽  
Depth Effect ◽  
Wave Source ◽  
The Difference ◽  
Rankine Sources

Applying linear marine hydrodynamics theory, the Kelvin wave source Green function of steady motion in finite depth was decomposed to three parts: array of simple Rankine sources, local distribution and wave part. Both at subcritical and supercritical speed, the singularity of integral function were eliminated by different integral path. The Kelvin source was distributed on the surface of ship by panel method, and the ship pressure distribution and wave pattern of ship in finite depth were calculated. The difference and connection between finite and infinite depth results were compared. It can provide the theoretical arithmetic base of improving the ship seaworthiness, increasing the speed and optimization of ship in river and offshore strip.

Water Entry and Exit of a Fully Ventilated Foil

1977 ◽  
Vol 21 (01) ◽  
pp. 44-68
Author(s):  
D. P. Wang
Keyword(s):  
Pressure Distribution ◽  
Finite Thickness ◽  
Deep Ocean ◽  
Thin Foil ◽  
Finite Depth ◽  
Present Theory ◽  
Small Time ◽  
Flow Motion ◽  
Linearized Theory ◽  
Initial Entry

The motion of a fully ventilated foil in water of both infinite and finite depth is considered. Part 1 deals with a two-dimensional, thin foil entering vertically into a deep ocean at high speeds. The foil is allowed to have small, time-dependent deformations, and the resulting flow around it is assumed to become fully ventilated. The problem is solved by linearized theory, the solution being divided into two different phases: initial entry and complete entry. The initial entry phase concerns the flow motion in which the foil is only partially submerged, and the complete entry phase concerns that in which the entire length of the foil becomes submerged. The pressure distribution on the foil is determined analytically up to a function of the time variable. The determination of the function depends on the solution of an integral equation. For illustration, the present theory is applied to a flat-plate foil in both uniform and nonuniform motions and to circular-arc foils in uniform motions. Part 2 considers the same foil in a layer of water of finite thickness. Here, the solution is divided into three different phases: the initial entry phase, the complete entry phase, and the exit phase. For the exit phase, the pressure distribution on the foil is explicitly determined. The result obtained in this work is intended for use in the design of the partially submerged supercavitating propeller.

An integral-equation method for determining the fluid motion due to a cylinder heaving on water of finite depth

1980 ◽  
Vol 372 (1748) ◽  
pp. 93-110 ◽  
Keyword(s):  
Integral Equation ◽  
Fundamental Solution ◽  
Integral Equations ◽  
Fluid Motion ◽  
Integral Equation Method ◽  
Finite Depth ◽  
The Body ◽  
Wave Source ◽  
Method Of Integral Equations ◽  
Infinite Set

The method of integral equations is used here to calculate the virtual mass of a half-immersed cylinder heaving periodically on water of finite constant depth. For general sections this method is more appropriate than the method of multipoles; particular sections that are considered are the circle and the ellipse. Green’s theorem is applied to the potential and to a fundamental solution (wave source) satisfying the conditions at the free surface, at the bottom and at infinity, but not necessarily on the body. An integral equation for the potential on the body only is thus obtained. For the simplest choice of fundamental solution the method breaks down at a discrete infinite set of frequencies, as is well known. When the fundamental solution was modified, however, a different integral equation could be obtained for the same unknown function and this was found not to break down for the circle and ellipse. The present numerical results are in good agreement with those obtained by the method of multipoles which for the circle is more efficient than the method of integral equations but which is not readily applicable to other sections. Much effort now goes into such calculations.

scholarly journals Assessment of Stickiness with Pressure Distribution Sensor Using Offset Magnetic Force

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 652 ◽  
Author(s):  
Takayuki Kameoka ◽  
Akifumi Takahashi ◽  
Vibol Yem ◽  
Hiroyuki Kajimoto ◽  
Kohei Matsumori ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Pressure Distribution ◽  
Magnetic Force ◽  
Tensile Force ◽  
Human Computer Interactions ◽  
Research Attention ◽  
Measuring Device ◽  
Measurement Results ◽  
The Difference ◽  
Intense Research

The quantification of stickiness experienced upon touching a sticky or adhesive substance has attracted intense research attention, particularly for application to haptics, virtual reality, and human–computer interactions. Here, we develop and evaluate a device that quantifies the feeling of stickiness experienced upon touching an adhesive substance. Keeping in mind that a typical pressure distribution sensor can only measure a pressing force, but not a tensile force, in our setup, we apply an offset pressure to a pressure distribution sensor and measure the tensile force generated by an adhesive substance as the difference from the offset pressure. We propose a method of using a magnetic force to generate the offset pressure and develop a measuring device using a magnet that attracts magnetic pin arrays and pin magnets; the feasibility of the method is verified with a first prototype. We develop a second prototype that overcomes the noise problems of the first, arising from the misalignment of the pins owing to the bending of the magnetic force lines at the sensor edges. We also obtain measurement results for actual samples and standard viscosity liquids. Our findings indicate the feasibility of our setup as a suitable device for measuring stickiness.

Effects of Intermittency of Feedback on a Compensatory Tracking Task

1976 ◽  
Vol 43 (3_suppl) ◽  
pp. 1339-1345 ◽  
Author(s):  
Henry S. R. Kao
Keyword(s):  
Tracking System ◽  
Wave Pattern ◽  
Open Loop ◽  
Tracking Task ◽  
Target Display ◽  
Random Wave ◽  
Tracking Tasks ◽  
The Difference ◽  
Effects Of Feedback ◽  
Task Efficiency

Target intermittence in tracking has been studied as frequency of target presentation at various time intervals. Task efficiency increased as a function of increased frequency of target display in open-loop tracking tasks, where the steady state of presentation resulted in the best performance. The present study examined effects of feedback intermittency in compensatory tracking as a major source of disruption of the motor-sensory feedback process in the closed-loop tracking system. Feedback intermittency is defined as the feedback of momentary sampling of the difference between target movements and the operator's control motion for specified time lengths before being displayed to him in a continuous tracking task. With a random wave pattern of 9.76 cpm, 7 magnitudes of 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, and 1.5 sec. were used to represent various levels of feedback intermittency. Task efficiency decreased as a function of increased magnitudes of intermittency. Results are discussed relative to the difference between target intermittence and feedback intermittency and their effects on different tracking tasks. The findings also establish the concept of feedback intermittency as a disturbing factor in compensatory tracking in degrading the operator's performance.

Developments in the calculation of the wavemaking resistance of ships

1988 ◽  
Vol 416 (1850) ◽  
pp. 115-147 ◽  
Keyword(s):  
Three Dimensional ◽  
Source Distribution ◽  
Rectilinear Motion ◽  
Kelvin Wave ◽  
Distribution Method ◽  
Wave Source ◽  
Qualitative And Quantitative ◽  
Theoretical Predictions ◽  
Computational Aspects ◽  
Quantitative Manner

The wavemaking resistance of a rigid ship in steady rectilinear motion at the free surface of a previously calm ocean is evaluated by means of a linearized three-dimensional potential-flow formulation. Solutions to the disturbance potential of the steady perturbed flow about the moving ship are obtained by means of a Kelvin wave source distribution method. Particular emphasis is placed on computational aspects and accurate and efficient algorithms for the evaluation of the fundamental Kelvin wave source potential function are discussed. To illustrate the proposed method, experimental and theoretical predictions are compared for a variety of ship forms. In general, this approach shows the correct behaviour of the variation of the wavemaking resistance with forward speed in both a qualitative and quantitative manner.

Calculation Method of Lubricant Film Pressure Distribution of Axial Piston Pump Slippers

2013 ◽  
Vol 328 ◽  
pp. 629-633
Author(s):  
Ya Jun Wang
Keyword(s):  
High Pressure ◽  
Pressure Distribution ◽  
Mass Conservation ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Shearing Flow ◽  
Pump Speed ◽  
Pressure Area ◽  
The Difference ◽  
Axial Piston

A method is implemented to get the pressure distribution of the axial piston pump slipper. Slipper was seen as translating thrust bearing, taking slipper tilt and spin in account, based on finite volume method, hydrodynamic and hydrostatic pressure has been calculated by using the mass conservation principle. For a representative element volume, the difference flow was averaged by the difference flow between the tilting planes, and the shearing flow by slipper translating was averaged by the shearing flow between the tilting planes. The numerical calculating result based two liquid resistance assume was compared, the results showed that two methods have got the same pressure distribution schematics, and the high pressure area locates at the slipper titling direction, but for the pressure values at high pressure area, the second method is slightly higher than the first method, and that the higher pump speed were, the higher the pressure values, and at the same pump speed, the slipper spin speed affects slightly the pressure, and at the lower pump speed, the lubricant pressure tends to the hydrostatic lubrication.

scholarly journals Follicular dynamic and repeatability of follicular wave development in Peranakan Ongole (PO) cattle

2016 ◽  
Vol 21 (1) ◽  
pp. 26 ◽  
Author(s):  
Muhammad Imron ◽  
Iman Supriatna ◽  
. Amrozi ◽  
Mohamad Agus Setiadi
Keyword(s):  
Bos Taurus ◽  
Research Result ◽  
Bos Indicus ◽  
Follicular Development ◽  
Wave Pattern ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Wave Patterns ◽  
The Difference ◽  
Follicular Dynamics

<p class="abstrak2">Superovulation treatment on PO cattle (Bos indicus) was less responsive compared to Bos taurus breed. It might due to the difference of their follicular dynamic. This study was conducted to investigate the follicular dynamics and its repeatability in PO cattle. Follicular dynamics observations conducted on 9 cows trough ultrasound scanning every day. Observations of wave patterns repeatability were performed in 6 cows which its wave pattern already known on the next consecutive IOI.  Research result indicated that PO cattle had 3 (66%) and 4-waves (34%) pattern. The first wave of 3 and 4-waves pattern emerged on day -0.4+0.9 and 1.4+1.1 respectively.  The second wave of 3 and 4-wave pattern emerged on day 9.8+1.5 and 7.4+1.9 respectively.  The pattern of 3 waves has a longer follicle dominant duration (11.6+1.5 day) in the first wave of estrous cycle, compared with 4 waves pattern (10+2.92 and 7+1.00 day respectively). The growth rate of dominant follicle was not different significantly between the 3 and 4-waves pattern (0.87+0.23 and 0.94+0.25 mm/day respectively). Similarly, ovulatory follicle diameter between 3 and 4-waves pattern was also not different significantly (12.24+12.34 and 12.30+12.23 mm respectively). Observation of wave patterns repeatability in 6 PO cows indicated that PO cattle had high repeatability in follicular wave pattern (0.88) and the number of growing follicle was 0.91.  This study resulted data for dynamic of follicular development, wave pattern, its repeatability which be expected to design the protocol of superovulation treatment or other reproduction technologies based on follicular dynamic to improve its result in PO cattle.</p><p> </p>

scholarly journals GRAPHICAL ANALYSIS OF FREE-SURFACE WAVE FIELDS FROM MOVING SHIPS AND A PAIR OF CONSECUTIVE POSTS

2019 ◽  
Vol 2019 (4) ◽  
pp. 7-22
Author(s):  
Павел Бимбереков ◽  
Pavel Bimberekov
Keyword(s):  
Water Transport ◽  
Water Surface ◽  
Free Water ◽  
Wave Pattern ◽  
Graphical Analysis ◽  
Wave System ◽  
Kelvin Wave ◽  
Experimental Tank ◽  
Wave Patterns ◽  
Pattern Forming

The paper presents a comparison of the photographic material of the wave patterns resulted from the movement of a ship in situ and a model ship, as well as from two consecutive posts, their regularities being found through graphical processing. The possibility to find the fore imaginary source of Kelvin wave pattern forming the ship's wave system is given at a distance of one wavelength before the top of the bow retaining wave. The equality of the length of trans-verse waves and divergent waves along the outer boundaries of the latter zone is fixed. It has been assumed that the intermediate waves generated between the main waves in the model ship and the posts are regular, imposition of wave patterns in a pair of consistently moving racks depending on the hit of the rear rack in the wave field of the first rack has been stated. Regularly occurring flows around moving posts are discussed. The bow and stern system of Kelvin waves in a ship wave sys-tem has been illustrated (the angle of the midpoint of diverging wave crests with the ship’s diamet-rical plane and the angle of diverging wave crests with the ship’s diametrical plane). The photo-graphs presented were taken in the experimental tank of Siberian State University of Water Transport (Novosibirsk State Academy of Water Transport) in 2006. A thin film naturally generat-ed on the water surface of the experimental tank and given a structure directed along the tank due to previous runs helped to visualize the distortion of the free water surface in better quality and to obtain clearly outlined contours in lighting.

scholarly journals Proof the Skewes’ number is not an integer using lattice points and tangent line

2021 ◽  
Vol 17 (2) ◽  
pp. 5-18
Author(s):  
V. Ďuriš ◽  
T. Šumný ◽  
T. Lengyelfalusy
Keyword(s):  
Counting Function ◽  
Prime Number Theorem ◽  
Prime Numbers ◽  
Integral Function ◽  
Lattice Points ◽  
Tangent Line ◽  
Miller Test ◽  
Logarithmic Integral ◽  
The Difference ◽  
Prime Counting Function

Abstract Skewes’ number was discovered in 1933 by South African mathematician Stanley Skewes as upper bound for the first sign change of the difference π (x) − li(x). Whether a Skewes’ number is an integer is an open problem of Number Theory. Assuming Schanuel’s conjecture, it can be shown that Skewes’ number is transcendental. In our paper we have chosen a different approach to prove Skewes’ number is an integer, using lattice points and tangent line. In the paper we acquaint the reader also with prime numbers and their use in RSA coding, we present the primary algorithms Lehmann test and Rabin-Miller test for determining the prime numbers, we introduce the Prime Number Theorem and define the prime-counting function and logarithmic integral function and show their relation.

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