scholarly journals On the issue of reduction of relative motion of the bow for a ship with energy-saving wing elements in headwind waves

2020 ◽  
pp. 52-58
Author(s):  
З.М. Хтет ◽  
К.В. Рождественский
Keyword(s):  
Experimental Data ◽  
Aspect Ratio ◽  
Energy Saving ◽  
Relative Motion ◽  
Vertical Displacement ◽  
Regular Waves ◽  
Method Of Calculation ◽  
Strip Theory ◽  
Vertical Displacements ◽  
Oscillating Foil

В статье рассматривается относительное перемещение носовой оконечности судна с энергосберегающими крыльевыми элементами на встречном волнении, а также результаты сравнения соответствующих расчетных и экспериментальных данных. Метод расчета основан на линейной теории поперечных сечений в частотной области. Сначала производится расчет продольной (вертикальной и килевой) качки судна встречном волнении, а затем расчетные данные используются для расчета относительных перемещений точек корпуса судна. Далее, для найденных численным методом смешанных колебаний носового и кормового крыльев, с привлечением теории Теодорсена колеблющегося профиля. В ходе расчетов демонстрируется влияние на относительное перемещение удлинения и площади энергосберегающих крыльев, а также эффект реализации относительного перемещения и вертикального ускорения при совместном использовании носового и кормового крыльев по сравнению со случаем использования только одного (носового или кормового) крыла. Полученные расчетные данные позволяют получить представление о механизме и эффективности снижения относительного перемещения на встречном волнении при качке судна с энергосберегающими крыльевыми элементами. Considered in the article are relative vertical displacement of the bow extremity of a ship with energy-saving wing elements in headwind regular waves, and also comparison of corresponding computational and experimental data. The method of calculation is based on a linear strip theory in frequency domain. At first, calculation is carried out of longitudinal (heaving & pitching) motions of a ship with and without wings in headwind waves, and then calculated results are employed to determine relative displacements of ship hull points. To account for the influence of inertial and damping effects of the wings attached to the hull we make use of Theodorsen theory of oscillating foil. Demonstrated in the course of calculations are the effects of wings aspect ratio and area as well as position with respect to the hull (bow wing, stern wing and bow & stern wings). Obtained computed data brings about better understanding of the mechanism and efficiency of reduction of vertical displacements of the hull points for a ship with energy-saving wings in headwind regular waves

scholarly journals To estimation of the Energy Efficiency Design Index (EEDI) for a ship with energy-saving wing devices

2021 ◽  
pp. 58-68
Author(s):  
К.В. Рождественский ◽  
М.Х. Зин
Keyword(s):  
Energy Efficiency ◽  
Aspect Ratio ◽  
Energy Saving ◽  
Wave Resistance ◽  
The Other ◽  
Large Aspect Ratio ◽  
Regular Waves ◽  
Strip Theory ◽  
Energy Efficiency Design Index ◽  
Oscillating Foil

В статье приводится оценка индекса проектной энергетической эффективности (EEDI) для судна с энергосберегающими крыльевыми устройствами на встречном регулярном волнении. Вначале на основе предыдущих работ авторов с применением линейной теории поперечных сечений определяются характеристики продольной (вертикальной и килевой) качки судна без крыльев, и такого же судна с крыльями большого удлинения, установленными на днище вблизи оконечностей с целью преобразования волновой энергии в дополнительную тягу. После определения параметров качки судна с крыльями как твердого тела, с применением теории Теодорсена колеблющегося профиля определяется средняя по периоду тяга энергосберегающих крыльевых элементов, совершающих поступательно-вращательные колебания. С другой стороны, в статье находится общее сопротивление системы «судно-крыльевые элементы». При этом применяется метод Холтропа в сочетании с теорие Бейкельмана-Герритсмы. Последняя дает возможность произвести оценку дополнительного волнового сопротивления по найденным параметрам продольной качки судна с крыльями и без крыльев. Затем оценивается значение индекса проектной энергетической эффективности (EEDI) контейнеровоза, снабженного энергосберегающими крыльями на встречном волнении. Исследование показывает, что установка на днище крыльевых элементов может использоваться как один из способов сокращения выброса углекислого газа и уменьшения в соответствии с требованиями Международной морской организации ИМО, значения индекса EEDI для репрезентативных морских условий. In this paper an estimation is presented of the Energy Efficiency Design Index (EEDI) for a ship with energy-saving wing devices in headwind regular waves. At first, based on previous works of the authors, there are determined with use of linear strip theory the characteristics of longitudinal (heaving and pitching) motions of a ship without wings and identical ship equipped with wings of large aspect ratio fitted on the bottom near extremities for the purpose of converting wave energy into additional thrust. After motions of the ship with wings as a solid boy are determined Theodorsen theory of oscillating foil is applied to calculate period averaged thrust of energy-saving wing elements, performing combined heave-pitch oscillations. On the other hand, the paper addresses the problem of determining overall drag of the “wing-plus-wings” system with use of Holtrop method combined with Beikelmann-Gerritsma theory. The latter enables carrying out an estimation of additional wave resistance based on the calculated parameters of the ship longitudinal motions with and without wings. Then follows an estimation of the EEDI for a containership equipped with wings in headwind regular waves. The study shows that fitting wing elements on the ship bottom can be seen as one of the methods for decreasing the magnitude of the EEDI for representative sea conditions as per requirements of the International Maritime Organization.

scholarly journals Influence of the aspect ratio of energy-saving wing elements fitted on the ship bottom upon spectral densities of longitudinal motions in irregular waves

2020 ◽  
pp. 45-51
Author(s):  
З.М. Хтет ◽  
К.В. Рождественский
Keyword(s):  
Aspect Ratio ◽  
Energy Saving ◽  
Calculated Data ◽  
Irregular Waves ◽  
Ship Motions ◽  
Wave Spectra ◽  
Regular Waves ◽  
Spectral Densities ◽  
Strip Theory ◽  
Oscillating Foil

В статье приводятся оценки спектральных плотностей качки судна с энергосберегающими крыльевыми элементами на встречном нерегулярном волнении, а также результаты сравнения расчета и эксперимента для продольной качки судна на регулярном волнении. Метод расчета основан на линейной теории поперечных сечений в частотной области. При этом сначала рассматривается продольная качка на встречном регулярном волнении с учетом демпфирующего и инерционного влияния крыльев посредством привлечения теории Теодорсена колеблющегося крыла. Определение спектральной плотности продольной качки на нерегулярном волнении проводится на основании формулы А.Я. Хинчина. Для расчета спектра волнения используется спектр JONSWAP по рекомендации DNV GL(2018). В ходе расчетов демонстрируется влияние на спектральные плотности удлинения и площади энергосберегающих крыльев, а также на спектральные плотности качки при совместном использовании носового и кормового крыльев по сравнению со случаем использования только одного из этих крыльев. Полученные расчетные данные дают представление о механизме снижения спектральных плотностей при использовании крыльев. The article presents some estimates of spectral densities of longitudinal motions for a ship with energy-saving wing devices in headwind irregular waves, and also comparisons of calculated and experimental data for longitudinal ship motions in headwind regular waves. The calculation method is based on a linear strip theory in frequency domain. Considered first are longitudinal motions of a ship in headwind regular waves with account of inertial and damping influence of the wings through use of Theodorsen oscillating foil theory. Spectral densities of longitudinal motions in irregular waves are determined with use of A.Ya. Khinchin formula and JONSWAP wave spectra as recommended by DNV GL (2018). Demonstrated in the course of calculations is the influence of the wings aspect ratio and area as well as their position with respect to the ship hull (bow wing, stern wing, bow & stern wings). Calculated data gives an idea of the mechanism of spectral densities reduction for motions of a ship with wing elements.

scholarly journals Исследования особенностей снижения продольной качки и дополнительного сопротивления судна с крыльевыми устройствами

2020 ◽  
Author(s):  
Z.M. Htet
Keyword(s):  
Energy Saving ◽  
Orbital Motion ◽  
Calculated Data ◽  
Ship Motions ◽  
Added Resistance ◽  
Regular Waves ◽  
Kinematic Parameters ◽  
Coupled Equations ◽  
Added Resistance In Waves ◽  
Oscillating Foil

В данной статье на основе предложенного расчета качки судна с энергосберегающими крыльевыми устройствами производится оценка мореходности и ходкости такого судна и возможности целенаправленного уменьшения амплитуд качки и снижения дополнительного сопротивления на волнении. Продольная качка судна заданного типа, обводов и размерений при наличии крыльевых элементов на заданном регулярном волнении рассчитывается с привлечением совместных уравнений вертикально-килевой качки с учетом демпфирования и инерции крыльевых устройств. При этом используется теория Теодорсена колеблющегося профиля и разложение нестационарных коэффициентов подъемной силы и момента по кинематическим параметрам при комбинировании вертикальных и угловых колебаний, и, в общем случае, в условиях воздействия орбитального движения жидкости. Для оценки дополнительного сопротивления используется теория Герритсмы и Бекельмана. В ходе расчетов демонстрируется влияние на дополнительное сопротивление удлинения и площади энергосберегающих крыльев, а также возможности снижения дополнительного сопротивления при совместном использовании носового и кормового крыльев по сравнению со случаем использования только одного (носового или кормового) крыла. Полученные расчетные данные позволяют получить представление о механизме влияния энергосберегающих крыльев на умерение амплитуд качки и снижение дополнительного сопротивления на волнении.In this article on the basis of the method for calculation of longitudinal motions of a ship with energy-saving wing devices proposed there is made an estimation of seaworthiness and seagoing capacity of such a ship and also of a possibility of directed decrease of ship motions amplitudes and added resistance in waves. The longitudinal motions of a ship of a given type, configuration and dimensions, in presence of wing elements, and in given regular waves is calculated with use of coupled equations of heave and pitch motions with account of damping and inertia of wing devices. Used therewith is Theodorsen theory of oscillating foil and expansion of lift and moment coefficients with respect to kinematic parameters for combined heave-and-pitch oscillations and, in general case, subject to action of orbital motion of fluid particles. To estimate added resistance the Beuklman-Gerritsma theory is used. Demonstrated in the course of calculations is the influence of aspect ratio and area of energy-saving wing upon the added resistance as well as upon its decrease when combining use of both bow and stern wings as compared to the case of using just one (bow or stern) wing. Obtained calculated data allow to understand the mechanism of the influence of energy-saving wings upon decrease of the amplitude of ship motions and the added resistance in waves.

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.

Concurrence of 1- and 3-Min Sit-to-Stand Tests with the 6-Min Walk Test in Idiopathic Pulmonary Fibrosis

Respiration ◽  
2021 ◽  
pp. 1-9
Author(s):  
Arnaud Fedi ◽  
Sophia Keddache ◽  
Sébastien Quétant ◽  
Alicia Guillien ◽  
Anestis Antoniadis ◽  
...  
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Daily Practice ◽  
Vertical Displacement ◽  
Physiological Parameters ◽  
Walk Test ◽  
Prognostic Information ◽  
Exercise Tests ◽  
Sit To Stand ◽  
Vertical Displacements

<b><i>Background:</i></b> In idiopathic pulmonary fibrosis (IPF), some physiological parameters measured during a 6-min walk test (6-MWT) impart reliable prognostic information. Sit-to-stand tests (STSTs) are field exercise tests that are easier to implement than the 6-MWT in daily practice. <b><i>Objectives:</i></b> The aims of the study were to test the reproducibility and compare 2 STSTs (the 1-min STST [1-STST] and the semi-paced 3-min chair rise test [3-CRT]) in IPF, and to determine if selected physiological parameters (speed of displacement and changes in pulse oxygen saturation [SpO<sub>2</sub>]) are interchangeable between the STSTs and the 6-MWT. <b><i>Methods:</i></b> Thirty-three patients with stable IPF were studied in 3 French expert centers. To test reproducibility, intra-class correlations (ICCs) of parameters measured during tests performed 7–14 days apart were calculated. To test interchangeability, the agreement and correlation of physiological responses measured during STSTs and during 6-MWT were studied. <b><i>Results:</i></b> Vertical displacements and changes in SpO<sub>2</sub> during both STSTs were reproducible, with ICCs ranging from 0.78 [0.63–0.87] to 0.95 [0.92–0.97]. Vertical displacements during 1-STST and 3-CRT were correlated with 6-MWT distance (correlation coefficients (<i>r</i>) of 0.72 and 0.77, respectively; <i>p</i> &#x3c; 0.001). Similarly, correlations were found between changes in SpO<sub>2</sub> measured during the 2 STSTs and the 6-MWT, with coefficients ranging from 0.73 to 0.91 (<i>p</i> &#x3c; 0.001). Distance walked and SpO<sub>2</sub> during 6-MWT were well estimated from vertical displacement and SpO<sub>2</sub> during the 2 STSTs, respectively. <b><i>Conclusion:</i></b> The correlations found between the 2 STSTs and the 6-MWT suggest that STSTs may be of interest to assess displacement and exercise-induced changes in SpO<sub>2</sub> in IPF patients.

Parametric study of multi-story, perforated, partially grouted masonry walls subjected to in-plane cyclic actions

2020 ◽  
Author(s):  
Klaus Medeiros ◽  
Kyle Chavez ◽  
Fernando S. Fonseca ◽  
Guilherme Parsekian ◽  
Nigel G. Shrive
Keyword(s):  
Experimental Data ◽  
Shear Strength ◽  
Aspect Ratio ◽  
Load Capacity ◽  
Axial Stress ◽  
Reinforcement Ratio ◽  
Masonry Walls ◽  
Finite Element Models ◽  
Initial Stiffness ◽  
Vertical Reinforcement

Finite element models were developed to assess the influence of several parameters on the load capacity, deflection, and initial stiffness of multi-story, partially grouted masonry walls with openings. The base model was validated with experimental data from three walls. The analyses indicated that the load capacity of masonry walls was considerably sensitive to the ungrouted and grouted masonry strengths and mortar shear strength; moderately sensitive to the vertical reinforcement ratio and aspect ratio; slightly sensitive to the axial stress; and almost insensitive to the opening size, reinforcement spacing, and horizontal reinforcement ratio. The deflection of the walls had well-defined correlations with the masonry strength, vertical reinforcement, axial stress and aspect ratio. The initial stiffness was especially sensitive to the axial stress and the aspect ratio, but weakly correlated with the opening size, and the spacing and size of the reinforcement.

Simulation of the Gap Resonance Between Two Rectangular Barges in Regular Waves by a Free Surface Viscous Flow Solver

2013 ◽  
Author(s):  
B. Elie ◽  
G. Reliquet ◽  
P.-E. Guillerm ◽  
O. Thilleul ◽  
P. Ferrant ◽  
...  
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Viscous Flow ◽  
Stokes Equations ◽  
Resonance Phenomenon ◽  
Navier Stokes ◽  
Regular Waves ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Gap Resonance

This paper compares numerical and experimental results in the study of the resonance phenomenon which appears between two side-by-side fixed barges for different sea-states. Simulations were performed using SWENSE (Spectral Wave Explicit Navier-Stokes Equations) approach and results are compared with experimental data on two fixed barges with different headings and bilges. Numerical results, obtained using the SWENSE approach, are able to predict both the frequency and the magnitude of the RAO functions.

scholarly journals The Assessment of Hydrologic- and Flood-Induced Land Deformation in Data-Sparse Regions Using GRACE/GRACE-FO Data Assimilation

2021 ◽  
Vol 13 (2) ◽  
pp. 235
Author(s):  
Natthachet Tangdamrongsub ◽  
Michal Šprlák
Keyword(s):  
Data Assimilation ◽  
Gravity Data ◽  
Regional Scale ◽  
Vertical Motion ◽  
Vertical Displacement ◽  
Spatial Coverage ◽  
Vertical Displacements ◽  
Land Deformation ◽  
Gravity Recovery ◽  
Central South

The vertical motion of the Earth’s surface is dominated by the hydrologic cycle on a seasonal scale. Accurate land deformation measurements can provide constructive insight into the regional geophysical process. Although the Global Positioning System (GPS) delivers relatively accurate measurements, GPS networks are not uniformly distributed across the globe, posing a challenge to obtaining accurate deformation information in data-sparse regions, e.g., Central South-East Asia (CSEA). Model simulations and gravity data (from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO)) have been successfully used to improve the spatial coverage. While combining model estimates and GRACE/GRACE-FO data via the GRACE/GRACE-FO data assimilation (DA) framework can potentially improve the accuracy and resolution of deformation estimates, the approach has rarely been considered or investigated thus far. This study assesses the performance of vertical displacement estimates from GRACE/GRACE-FO, the PCRaster Global Water Balance (PCR-GLOBWB) hydrology model, and the GRACE/GRACE-FO DA approach (assimilating GRACE/GRACE-FO into PCR-GLOBWB) in CSEA, where measurements from six GPS sites are available for validation. The results show that GRACE/GRACE-FO, PCR-GLOBWB, and GRACE/GRACE-FO DA accurately capture regional-scale hydrologic- and flood-induced vertical displacements, with the correlation value and RMS reduction relative to GPS measurements up to 0.89 and 53%, respectively. The analyses also confirm the GRACE/GRACE-FO DA’s effectiveness in providing vertical displacement estimates consistent with GRACE/GRACE-FO data while maintaining high-spatial details of the PCR-GLOBWB model, highlighting the benefits of GRACE/GRACE-FO DA in data-sparse regions.

Dynamics of a Free Heaving and Prescribed Pitching Hydrofoil in a Turbulent Flow, With a Fluid-Structure Interaction Approach

2018 ◽  
Author(s):  
P. Brousseau ◽  
M. Benaouicha ◽  
S. Guillou
Keyword(s):  
Fluid Structure Interaction ◽  
Vertical Displacement ◽  
Rotational Displacement ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction ◽  
Maximum Angle ◽  
High Maximum ◽  
Oscillating Foil ◽  
Interaction Approach

This paper deals with the dynamics of an oscillating foil, describing a free heaving (vertical displacement) and prescribed pitching (rotational displacement) movement which is computed from its position in two different ways. A fluid-structure interaction approach is chosen, as the physics of the flow and the structure are strongly coupled. The flow is unsteady, turbulent and incompressible. The pressure/velocity problem is solved using SIMPLEC scheme. First, the pitching movement is considered as a given continuous function of the hydrofoil heaving position. Second, the pitching motion is performed alternately at the end of each heave cycle. For each case, two maximum angles of attack and one heaving amplitudes are studied. Preliminary results showed that a high maximum angle of attack generates more lift hydrodynamics force, but also requires more energy to perform the rotation of pitch.

scholarly journals Seismic Activity of the Manisa Fault Zone in Western Turkey Constrained by Cosmogenic 36Cl Dating

Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 451
Author(s):  
Nasim Mozafari ◽  
Çağlar Özkaymak ◽  
Dmitry Tikhomirov ◽  
Susan Ivy-Ochs ◽  
Vasily Alfimov ◽  
...  
Keyword(s):  
Fault Zone ◽  
Normal Fault ◽  
Vertical Displacement ◽  
Historical Records ◽  
Western Turkey ◽  
Slip Rates ◽  
Vertical Displacements ◽  
Surface Ruptures ◽  
Fault Scarps ◽  
Calculated Average

This study reports on the cosmogenic 36Cl dating of two normal fault scarps in western Turkey, that of the Manastır and Mugırtepe faults, beyond existing historical records. These faults are elements of the western Manisa Fault Zone (MFZ) in the seismically active Gediz Graben. Our modeling revealed that the Manastır fault underwent at least two surface ruptures at 3.5 ± 0.9 ka and 2.0 ± 0.5 ka, with vertical displacements of 3.3 ± 0.5 m and 3.6 ± 0.5 m, respectively. An event at 6.5 ± 1.6 ka with a vertical displacement of 2.7 ± 0.4 m was reconstructed on the Mugırtepe fault. We attribute these earthquakes to the recurring MFZ ruptures, when also the investigated faults slipped. We calculated average slip rates of 1.9 and 0.3 mm yr−1 for the Manastır and Mugırtepe faults, respectively.

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