scholarly journals MOVEMENT OF THE PARTICLE ON THE INTERNAL SURFACE OF THE SPHERICAL SEGMENT ROTATING ABOUT A VERTICAL AXIS

2020 ◽  
pp. 79-88
Author(s):  
Sergiy Pylypaka ◽  
Victor Nesvidomin ◽  
Tatiana Volina ◽  
Larysa Sirykh ◽  
Liudmyla Ivashyna

The particle relative motion on a spherical segment rotating about a vertical axis was considered in the article. The differential equations of the relative displacement of a particle were completed and solved by numerical methods. The relative and absolute trajectories of particle motion and graphs of relative and absolute velocity changes were constructed. The regularity of particle motion as it is lifted over the surface was found out. The conducted experimental research has confirmed the received theoretical results.

2021 ◽  
Vol 3 (1) ◽  
pp. 27-36
Author(s):  
T. Volina ◽  
◽  
S. Pylypaka ◽  
A. Nesvidomin ◽  
◽  
...  

The relative motion of a particle on the inner surface of a horizontal spherical disk along a vertical blade mounted in the radial direction is considered in the article. The disk rotates around a vertical axis with a given angular velocity. A system of differential equations of motion of a particle is compiled and solved by numerical methods. The kinematic characteristics of the motion are found, the regularities of the relative motion of the particle on the surface of the cylinder are clarified. Graphs characterizing the motion of a particle at certain given parameters are constructed, namely: graph of angle change, which sets the position of the particle on the surface of the sphere in the direction of the meridian, graphs of absolute and relative velocities, graphs of change of forces of the reaction of the spherical disk and blade. Numerical integration of the obtained differential equation showed that in half a second the particle rises to the height of the hemisphere, and then begins to fall. In this case, the descent alternates with the rise to a complete stop of the particle at a certain height, i.e. the particle “sticks” and then rotates with the hemisphere. The angle of “sticking” can be found analytically. In addition, numerical calculation methods have shown that at zero value of the friction coefficient of the particle on the disk surface, i.e. at its absolutely smooth surface, and at the non-zero value of the friction coefficient of the blade surface, and at an unlimited increase of the disk angular velocity the particle “sticks” at the height of the center of the sphere. If both surfaces are absolutely smooth, then the damping oscillations of the angle that determines the position of the particle on the surface of the sphere in the direction of the meridian, occur indefinitely. The working surface of the disk of the centrifugal apparatus, which is made in the form of a spherical segment, provides the beginning of the flight of the particle at the time of ascent from the disk at a given angle to the horizontal plane, increasing the scattering area of the technological material. The analytical description of the particle motion obtained in the article makes it possible to investigate its acceleration along with the blades of the disk and to find the relative and absolute velocities at the moment of particle ascent from the disk. The found analytical dependencies allow determining the influence of constructive and technological parameters on the process of particle acceleration.


Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hiroaki Eto ◽  
Chang-Kyu Rheem ◽  
Osamu Enomoto

While a type of marine turbine for tidal current generation can be chosen from several types, a vertical axis marine turbine (VAMT) should be better in Japan because sea areas around Japanese islands where current velocity is sufficient are limited. This study conducted a sea test of a VAMT of a floating type installed with six straight pitch-controllable blades. The cycloidal mechanism was adapted for the pitch control. The purpose of the study is to understand effects of ocean waves and motion of a floating body on turbine performance and behaviours of the VAMT in unideal current conditions. Besides, the data taken should be effective to consider that effects in order to design VAMTs. The setup with the setting angle of −30 degrees suggested highest performance from the sea tests, then 15% in maximum turbine power and maximum output was 40W. Ocean waves strongly affected on the turbine performance because fluid velocity changes due to ocean waves and it was unable to neglect the variation of the velocity in spite of small. The characteristics of the turbine sensitively varied because of ocean waves. The results suggested that during accelerating and decelerating incoming fluid speed, characteristics of the turbine were different in each case.


2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Chengjian Zhang

This paper presents a class of new numerical methods for nonlinear functional-integrodifferential equations, which are derived by an adaptation of Pouzet-Runge-Kutta methods originally introduced for standard Volterra integrodifferential equations. Based on the nonclassical Lipschitz condition, analytical and numerical stability is studied and some novel stability criteria are obtained. Numerical experiments further illustrate the theoretical results and the effectiveness of the methods. In the end, a comparison between the presented methods and the existed related methods is given.


2012 ◽  
Vol 271-272 ◽  
pp. 981-985
Author(s):  
You Yi Wang ◽  
Yang Zhao ◽  
Wen Lai Ma

Frame structure is widely used in practical projects. For jitter of the frame structure excited by median and high frequency disturbances, firstly, the dynamic model of thin plate substructure is built by wave method, and then the dynamic model of frame structure is established by combining wave method and substructure technique. At last, the accurate dynamic response was obtained. The simulation of dynamic characteristic is made, and simulation results are compared with FEM results. On this basis, modal experiment and frequency response experiment is done to verify theoretical results. In comparison to FEM, the results by wave method are accurate in low frequency regions, and the results are more accurate in the median and high frequency regions. The experiment proves wave method is correct and effective for jitter transmission analysis of frame structure in the median and high frequency regions.


2015 ◽  
Vol 19 ◽  
pp. 715-721
Author(s):  
Raluca Dora Ionescu ◽  
Ioan Szava ◽  
Sorin Vlase ◽  
Mircea Ivanoiu ◽  
Renata Munteanu

2008 ◽  
Vol 400-402 ◽  
pp. 551-557 ◽  
Author(s):  
Bao Zhu Cao ◽  
Yao Chun Zhang ◽  
Yue Ming Zhao

Experimental research on square and octagonal concrete filled thin-walled steel tube long columns of 6 specimens in axial compression and 8 specimens in eccentric compression is undertaken. The relationship of global buckling bearing capacity of the columns and local buckling of the steel tubes is obtained. The test indicates that local buckling occurs in steel tube of each column before it reaches ultimate capacity, and has little effect on global buckling performance. The ultimate load decreases obviously with the increase of slender ratio and eccentricity. The ductility of columns increases with the increase of steel ratio in composite sections. Composite beam element of ANSYS is adopted in the finite element analysis. The theoretical results are agreed well with test..


2020 ◽  
Vol 11 (4) ◽  
pp. 101-105
Author(s):  
T. M. Volina ◽  
◽  
S. F. Pylypaka ◽  

The differential equations of relative movement of a particle on the external surface of the inclined cylinder which carries out oscillatory movement were received in the article. All points of the cylinder describe circles in horizontal planes. The equations were solved by numerical methods and the trajectories of the relative motion of the particle on the surface of the cylinder are constructed. Graphs of other kinematic characteristics as a function of time are given. Partial cases when the axis of the cylinder is located horizontally or at an angle of friction to the horizontal plane are considered.


2007 ◽  
Vol 13 (4) ◽  
pp. 317-323
Author(s):  
Juozas Valivonis ◽  
Tomas Skuturna

The article presents the analysis of the cracking moment and the strength of beams reinforced with external carbon fibre. Experimental research of beams strengthened in this way has been carried out. Three different methods of anchoring external reinforcement were applied to strengthen the beams. The influence of anchorage on the cracking moment and the strength of the beams has been defined. Design methods for defining the cracking moment and the strength have been presented. The design procedure for defining the cracking moment evaluates the curvilinear stress diagrams of concrete under tension and compression. The design procedure for defining the strength of the structures evaluates the stiffness of the contact between the carbon fibre and the concrete. The design results are provided. Comparative analysis of the experimental and the theoretical results has been performed.


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