scholarly journals Investigation of nonlinear static displacements during the ship’s motions in various confined waterways

2021 ◽  
pp. 28-36
Author(s):  
В.Ю. Семенова ◽  
Н.А. Павлючук
Keyword(s):  
Shallow Water ◽  
Vertical Wall ◽  
Relative Depth ◽  
Method Of Integral Equations ◽  
Wave Drift ◽  
Vertical Displacements ◽  
Heading Angle ◽  
Domestic Practice ◽  
Nonlinear Static

В статье проводится исследование нелинейных статических перемещений, возникающих в случае качки судна на мелководье, качки судна параллельно вертикальной стенке и при совместной качке двух судов на мелководье. Определение статических перемещений осуществляется на основании определения соответствующих сил волнового дрейфа по методам, разработанным в предшествующих работах. Данные методы основаны на применении метода интегральных уравнений и зеркальных отображений для случая качки судна параллельно вертикальной стенки. Проведенное исследование в отечественной практике является новым. В статье приводятся результаты расчетов нелинейных статических перемещений, возникающих при вертикальной, бортовой и килевой качки различных типов судов. Проводится исследование влияния различных факторов на их величины, а именно: изменения относительной глубины фарватера, изменения расстояния между судном и вертикальной стенкой, изменения расстояния между судами, курсового угла. Показано увеличение значений нелинейных статических углов крена и дифферента, а также вертикальных перемещений при уменьшении относительной глубины, уменьшении расстояния между судами и расстояния между судном и стенкой. Приведено сравнение значений статических перемещений, возникающих в различных стесненных фарватерах при прочих равных условиях. The article investigates nonlinear static displacements arising in the case of a ship’s motions in shallow water, motions of a ship parallel to a vertical wall and during coupled motions of two ships in shallow water. The determination of static displacements is carried out on the basis of determining the corresponding forces of wave drift according to the methods developed in previous works. These methods are based on the application of the method of integral equations and mirror images for the case of the ship’s motions parallel to the vertical wall. The research carried out in domestic practice is new. The article presents the results of calculations of nonlinear static displacements occurring during heaving, rolling and pitching of various types of ships. A study of the influence of various factors on their values is being carried out, namely: changes in the relative depth of the waterway, changes in the distance between the ship and the vertical wall, changes in the distance between ships, heading angle. An increase in the values of nonlinear static angles of roll and trim, as well as vertical displacements with a decrease in the relative depth, a decrease in the distance between ships and the distance between the ship and the wall, is shown. A comparison of the values of static displacements arising in various confined waterways, all other things being equal, is given.

scholarly journals Determination of exciting forces and amplitude-frequency characteristics during coupled motions of two ships in shallow water parallel to the vertical wall

2021 ◽  
pp. 37-47
Author(s):  
В.Ю. Семенова ◽  
К.И. Баканов
Keyword(s):  
Shallow Water ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Joint Effect ◽  
Frequency Characteristics ◽  
Diffracted Waves ◽  
Exciting Forces ◽  
Domestic Practice ◽  
Simultaneous Influence

В статье рассматривается определение возмущающих сил и моментов и амплитудно-частотных характеристик возникающих при совместной качке двух судов в условиях мелководья параллельно вертикальной стенке на основании решения трехмерной потенциальной задачи. Определение потенциалов дифрагированного волнения, необходимых для расчетов возмущающих сил, осуществляется на основании методов интегральных уравнений и зеркальных отображений. Представленное решение в отечественной практике является новым. В статье приводятся результаты расчетов возмущающих сил и амплитудно-частотных характеристик поперечно-горизонтальных, вертикальных и бортовых колебаний, 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 возмущающих сил и амплитудно-частотных характеристик, 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 возмущающих сил при уменьшении расстояний между судами и между судами и вертикальной стенкой. Также показано значительное совместное влияние вертикальной стенки и второго судна на амплитудно-частотные характеристики по сравнению со случаем качки судна на мелководье. The article discusses the determination of the exciting forces and moments and amplitude-frequency characteristics arising from the coupled motions of two ships in shallow water conditions parallel to the vertical wall based on the solution of a three-dimensional potential problem. The determination of the potentials of diffracted waves, necessary for calculating the exciting forces, is carried out on the basis of the methods of integral equations and mirror images. The presented solution is new in domestic practice. The article presents the results of calculations of exciting forces and amplitude-frequency characteristics of swaying, heaving and rolling arising from the motions of two identical ships located in the beam waves and parallel to the vertical wall, depending on the change in the distances both between ships and between ships and vertical wall. A study of the influence of various waterways on the magnitude of exciting forces and amplitude-frequency characteristics is being carried out, 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 exciting forces is shown with a decrease in the distances between ships and between ships and the vertical wall. A significant joint effect of the vertical wall and the second ship on the amplitude-frequency characteristics is also shown in comparison with the case of the ship oscillating in shallow water.

scholarly journals On the influence of the speed on the amplitude of the coupled motionsships in shallow water

2020 ◽  
Author(s):  
В.Ю. Семенова ◽  
Д.В. Казаков
Keyword(s):  
Shallow Water ◽  
Three Dimensional ◽  
Relative Depth ◽  
Parallel Arrangement ◽  
Different Types ◽  
Previous Solution ◽  
Heading Angle ◽  
Response Amplitude Operators ◽  
National Practice

В статье рассматривается определение амплитудно-частотных характеристик, возникающих при совместной качке двух судов в условиях мелководья на основании ранее полученного решения трехмерной потенциальной задачи. Определение амплитуд качки обоих судов осуществляется на основании решения системы 12 связанных дифференциальных уравнений. Представленное решение в отечественной практике является новым. Особое внимание уделяется исследованию влияния скорости хода при параллельном расположении двух судов на амплитуды качки, имеющих место при различных курсовых углах. Расчеты приведены для разных сочетаний судов. Анализ полученных результатов показывает различное поведение значений амплитуд различных видов качки при расположении судов параллельно друг другу при увеличении скорости хода и курсового угла. Показано влияние гидродинамического взаимодействия при качке на косых углах, проявляющееся во взаимодействии бортовой, килевой и вертикальной качки. Отмечается наименьшее влияние скорости хода при расположении двух судов лагом, проявляющееся в уменьшении бортовой качки. Делается вывод об одинаковом влиянии скорости хода на амплитуды качки при различных сочетаниях относительной глубины и расстояния между судами. This paper is about the determination of the response amplitude operators during the coupled motions of two ships in shallow water, based on the previous solution of the three dimensional potential problem. The determination of the amplitudes of the motions of both ships is based on the solution of a system of 12 coupled differential equations. The solution presented in the national practice is new. Particular attention is paid to the study of the effect of speed with a parallel arrangement of two ships on the amplitude of the motions that occur at different course angles. Calculations are given for different combinations of ships. The analysis of the results obtained shows different behavior of the values ​​of the amplitudes of different types of motions when the ships are positioned parallel to each other with increasing speed and heading angle. The influence of hydrodynamic interaction during motions at oblique angles is shown, which manifests itself in the interaction of rolling, pitching and heaving. The smallest influence of the speed of the course is noted when two ships are located in beam waves, which is manifested in a decrease in rolling. The conclusion is made about the same influence of the speed of the course on the amplitude of the roll at various combinations of the relative depth and distance between the vessels.

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 Determination of nonlinear second-order diffraction forces acting on a ship in shallow water conditions based on the use of three-dimensional potential theory

2021 ◽  
pp. 25-33
Author(s):  
В.Ю. Семенова ◽  
Д.А. Альбаев
Keyword(s):  
Shallow Water ◽  
Potential Theory ◽  
Three Dimensional ◽  
Nonlinear Boundary Conditions ◽  
Second Order ◽  
Relative Depth ◽  
Incoming Wave ◽  
Nonlinear Diffraction ◽  
Water Conditions

В статье рассматривается метод определения нелинейных дифракционных сил, действующих на судно в условиях мелководья на основании трехмерной потенциальной теории. Производится оценка влияния относительной глубины водоема Н/Т на данные нелинейные силы. Для нахождения нелинейных сил, требуется определение потенциалов второго порядка малости. Решение основано на методах малого параметра, интегральных уравнений Фредгольма и функции Грина для случая мелководья. Данное решение является новым для отечественной практики. При определении потенциалов второго порядка учитываются нелинейные граничные условия на свободной поверхности жидкости и на смоченной поверхности судна. На основании изложенного метода разработана программа расчета нелинейных сил при различных Н/Т. Приводятся результаты расчетов сил и моментов для трех различных типов судов. Приведено сравнение с расчетами, основанными на двумерной теории. Особое внимание уделяется учету потенциала набегающего волнения второго порядка. Учитывается его вклад в образовании нелинейных дифракционных сил. Приводится сравнение расчетов с учетом влияния данного потенциала и без него. The article discusses a method for determining nonlinear diffraction forces acting on a ship in shallow water conditions on the basis of a three-dimensional potential theory. The influence of the relative depth of the fluid Н/Т on these nonlinear forces is assessed. To determine them, it is necessary to calculate the potentials of the second order of smallness. The solution of the problem is carried out on the basis of small parameter methods, Fredholm’s integral equations and Green’s function for a fluid of limited depth. The presented solution in national practice is new. During the determination of the second order potentials, nonlinear boundary conditions on the free surface of the liquid and on the wetted surface of the ship are taken into account on the basis of methods program was developed, considering various Н/Т. The results of calculations of the forces and moments for three types of different ships are presented. Comparison with calculations based on two-dimensional theory is given. Special attention is paid to taking into account the potential of the second-order of incoming wave. Its contribution to the formation of nonlinear diffraction forces is taken into account. A comparison of calculations with and without the influence of this potential is given

scholarly journals The Concept of Accuracy Analysis of the Vertical Displacements Gained from the Hydrostatic Levelling Systems’ Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4842
Author(s):  
Waldemar Kamiński
Keyword(s):  
Accuracy Assessment ◽  
Theoretical Models ◽  
Vertical Displacement ◽  
Serial Connection ◽  
Vertical Displacements ◽  
Comprehensive Determination ◽  
The One ◽  
The Individual ◽  
Reference Sensor

Nowadays, hydrostatic levelling is a widely used method for the vertical displacements’ determinations of objects such as bridges, viaducts, wharfs, tunnels, high buildings, historical buildings, special engineering objects (e.g., synchrotron), sports and entertainment halls. The measurements’ sensors implemented in the hydrostatic levelling systems (HLSs) consist of the reference sensor (RS) and sensors located on the controlled points (CPs). The reference sensor is the one that is placed at the point that (in theoretical assumptions) is not a subject to vertical displacements and the displacements of controlled points are determined according to its height. The hydrostatic levelling rule comes from the Bernoulli’s law. While using the Bernoulli’s principle in hydrostatic levelling, the following components have to be taken into account: atmospheric pressure, force of gravity, density of liquid used in sensors places at CPs. The parameters mentioned above are determined with some mean errors that influence on the accuracy assessment of vertical displacements. In the subject’s literature, there are some works describing the individual accuracy analyses of the components mentioned above. In this paper, the author proposes the concept of comprehensive determination of mean error of vertical displacement (of each CPs), calculated from the mean errors’ values of components dedicated for specific HLS. The formulas of covariances’ matrix were derived and they enable to make the accuracy assessment of the calculations’ results. The author also presented the subject of modelling of vertical displacements’ gained values. The dependences, enabling to conduct the statistic tests of received model’s parameters, were implemented. The conducted tests make it possible to verify the correctness of used theoretical models of the examined object treated as the rigid body. The practical analyses were conducted for two simulated variants of sensors’ connections in HLS. Variant no. I is the sensors’ serial connection. Variant no. II relies on the connection of each CPs with the reference sensor. The calculations’ results show that more detailed value estimations of the vertical displacements can be obtained using variant no. II.

scholarly journals Biofilm Localization in the Vertical Wall of Shaking 96-Well Plates

Scientifica ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Luciana C. Gomes ◽  
Joana M. R. Moreira ◽  
Manuel Simões ◽  
Luís F. Melo ◽  
Filipe J. Mergulhão
Keyword(s):  
Low Cost ◽  
Vertical Wall ◽  
Spatial Location ◽  
Strain Rates ◽  
Microtiter Plates ◽  
Equipment Availability ◽  
Cell Accumulation ◽  
Electron Microscopes ◽  
Air Liquid Interface

Microtiter plates with 96 wells are being increasingly used for biofilm studies due to their high throughput, low cost, easy handling, and easy application of several analytical methods to evaluate different biofilm parameters. These methods provide bulk information about the biofilm formed in each well but lack in detail, namely, regarding the spatial location of the biofilms. This location can be obtained by microscopy observation using optical and electron microscopes, but these techniques have lower throughput and higher cost and are subjected to equipment availability. This work describes a differential crystal violet (CV) staining method that enabled the determination of the spatial location ofEscherichia colibiofilms formed in the vertical wall of shaking 96-well plates. It was shown that the biofilms were unevenly distributed on the wall with denser cell accumulation near the air-liquid interface. The results were corroborated by scanning electron microscopy and a correlation was found between biofilm accumulation and the wall shear strain rates determined by computational fluid dynamics. The developed method is quicker and less expensive and has a higher throughput than the existing methods available for spatial location of biofilms in microtiter plates.

scholarly journals The development of civil society in Ukraine as an object of the state influence

2012 ◽  
Vol 2012 (3) ◽  
pp. 165-180
Author(s):  
Viktor Melnyuchenko
Keyword(s):  
Civil Society ◽  
The State ◽  
State Participation ◽  
Domestic Practice

Article is devoted to the determination of the content of civil society, the assessment on this basis of domestic practice in the part of necessity of boundaries and tools of state participation in the development of civil society. Outlined contradictions of views on civil society and its development, formulated certain proposals on perspectives of development of civil society and participation in promoting of this development of the Ukrainian state.

scholarly journals Natural convection air flow in vertical upright-angled triangular cavities under realistic thermal boundary conditions

2016 ◽  
Vol 20 (5) ◽  
pp. 1407-1420 ◽  
Author(s):  
Jaime Sieres ◽  
Antonio Campo ◽  
José Martínez-Súarez
Keyword(s):  
Natural Convection ◽  
Vertical Wall ◽  
Aperture Angle ◽  
Temperature Fields ◽  
Uniform Heat Flux ◽  
Thermal Boundary Conditions ◽  
Nusselt Numbers ◽  
Horizontal Wall ◽  
Rayleigh Numbers

This paper presents an analytical and numerical computation of laminar natural convection in a collection of vertical upright-angled triangular cavities filled with air. The vertical wall is heated with a uniform heat flux; the inclined wall is cooled with a uniform temperature; while the upper horizontal wall is assumed thermally insulated. The defining aperture angle ? is located at the lower vertex between the vertical and inclined walls. The finite element method is implemented to perform the computational analysis of the conservation equations for three aperture angles ? (= 15?, 30? and 45?) and height-based modified Rayleigh numbers ranging from a low Ra = 0 (pure conduction) to a high 109. Numerical results are reported for the velocity and temperature fields as well as the Nusselt numbers at the heated vertical wall. The numerical computations are also focused on the determination of the value of the maximum or critical temperature along the hot vertical wall and its dependence with the modified Rayleigh number and the aperture angle.

A Comparative Investigation of Structural Performance of Typical and Non-Ducitle Public RC Buildings Strengthened Using Friction Dampers and RC Walls

2017 ◽  
pp. 112-127 ◽  
Author(s):  
Erkan Akpinar ◽  
Seckin Ersin
Keyword(s):  
Ground Motion ◽  
Comparative Investigation ◽  
Rc Buildings ◽  
Post Intervention ◽  
Friction Dampers ◽  
History Analysis ◽  
Response History Analysis ◽  
Nonlinear Static ◽  
Selection Of

Strengthening of non-ductile public buildings is a never-ending issue. Selection of the suitable strengthening method and appropriate analysis type for the assessment of pre- and the post-intervention performances are still open to question. The displacement or drift limitations are crucial as well as demand capacity ratios for determination of such buildings performance under severe ground motion. In this chapter, an investigation of seismic performance focused on displacement criterion of strengthened non-ductile public RC buildings in Turkey is presented. Both the nonlinear static and response history analysis were conducted. Friction dampers which are fairly modern technique and conventional RC wall implementation method were introduced to as-is building. For the simplicity and the easy of the process, 2D frame selected for investigation. Comparison of the aforementioned techniques for non-ductile public RC buildings and performances particularly by means of displacement obtained using different methods for those investigated schemes are carried out and presented in the chapter.

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