scholarly journals Lateral and Overturning Resistance of Wind Turbine Foundations Reinforced with Piles on Bedrock by Modelling Experiments

2021 ◽  
Vol 9 (9) ◽  
pp. 919
Author(s):  
Gichun Kang ◽  
Seong-Kyu Yun ◽  
Tae-Hyung Kim ◽  
Jiseong Kim
Keyword(s):  
Wind Turbine ◽  
Cross Sections ◽  
Boundary Surface ◽  
Bending Moment ◽  
Vertical Displacement ◽  
Cross Sectional ◽  
Right Hand ◽  
Lateral Resistance ◽  
Rubble Mound ◽  
The Right

This study evaluated the lateral and overturning resistance of wind turbine foundations reinforced with piles on bedrock through model experiments. In particular, changes in lateral and overturning resistance of wind turbine foundations were analyzed according to cross-sectional size and the presence of piles of wind turbine foundations. As a result, by reducing the cross-section, the lateral resistance of the pile-reinforced wind turbine foundation was compared to the existing wind turbine foundation with large cross-sections and was shown to be 1.68 times greater. In the case of vertical displacements affecting overturning, the safety of overturning was also greater, as the vertical displacement of the pile-reinforced wind turbine foundation was 36% smaller than the existing wind turbine foundation. As a result of the unidirectional cyclic load on a pile-reinforced wind turbine foundation, lateral resistance value was similar to that of the static load in target displacement value, and it showed that the elastic resilience was very large due to pile reinforcement. According to the bending moment measurement of piles embedded in wind turbine foundations and bedrock, bending moments were large in the order of the front row, the right-hand row, and the back row, while the maximum bending moment generation was found on the boundary surface of the wind turbine foundation and the rubble mound layer for the front row, as well as on the boundary surface of the rubble mound layer and bedrock for the right-hand row and back row.

Simulation of Flow Field on a Large Scale Wind Turbine

2008 ◽  
Author(s):  
I. Janajreh ◽  
C. Ghenai
Keyword(s):  
Flow Field ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Cross Sections ◽  
Large Scale ◽  
Wind Farms ◽  
Operating Characteristics ◽  
Cross Sectional ◽  
Capital Costs

Large scale wind turbines and wind farms continue to evolve mounting 94.1GW of the electrical grid capacity in 2007 and expected to reach 160.0GW in 2010 according to World Wind Energy Association. They commence to play a vital role in the quest for renewable and sustainable energy. They are impressive structures of human responsiveness to, and awareness of, the depleting fossil fuel resources. Early generation wind turbines (windmills) were used as kinetic energy transformers and today generate 1/5 of the Denmark’s electricity and planned to double the current German grid capacity by reaching 12.5% by year 2010. Wind energy is plentiful (72 TW is estimated to be commercially viable) and clean while their intensive capital costs and maintenance fees still bar their widespread deployment in the developing world. Additionally, there are technological challenges in the rotor operating characteristics, fatigue load, and noise in meeting reliability and safety standards. Newer inventions, e.g., downstream wind turbines and flapping rotor blades, are sought to absorb a larger portion of the cost attributable to unrestrained lower cost yaw mechanisms, reduction in the moving parts, and noise reduction thereby reducing maintenance. In this work, numerical analysis of the downstream wind turbine blade is conducted. In particular, the interaction between the tower and the rotor passage is investigated. Circular cross sectional tower and aerofoil shapes are considered in a staggered configuration and under cross-stream motion. The resulting blade static pressure and aerodynamic forces are investigated at different incident wind angles and wind speeds. Comparison of the flow field results against the conventional upstream wind turbine is also conducted. The wind flow is considered to be transient, incompressible, viscous Navier-Stokes and turbulent. The k-ε model is utilized as the turbulence closure. The passage of the rotor blade is governed by ALE and is represented numerically as a sliding mesh against the upstream fixed tower domain. Both the blade and tower cross sections are padded with a boundary layer mesh to accurately capture the viscous forces while several levels of refinement were implemented throughout the domain to assess and avoid the mesh dependence.

Simplified Procedure to Estimate the Wind Turbine Blade Aerodynamic Loadings Without Using CFD

2013 ◽  
Author(s):  
Fouad Mohammad ◽  
Emmanuel Ayorinde
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Equations Of Motion ◽  
Wind Turbine Blade ◽  
Aerodynamic Load ◽  
Horizontal Axis Wind Turbine ◽  
Cross Sectional ◽  
Flow Angle ◽  
Blade Length ◽  
The Right

The aerodynamic loadings that act on the blade of a horizontal axis wind turbine change as a function of time due to the instantaneous change of the wind speed, the wind direction and the blade position. The new contribution in this study is the introduction of a simplified non CFD based procedure for the calculation of all the aerodynamic loadings acting on a wind turbine blade. The premise of the current simplified model is that (a) the forces can be modeled by a set of point loads rather than distributed pressures, and (b) the magnitudes of these point loads can be estimated using the below load formulas, (c) an interpolation scheme needed to have all computed forces and moments as a function of the blade lengthwise x. Considering a 14m blade length and utilizing a time dependent set of parameters such as angle of attack, material and air density, wind and blade speed, flow angle, yaw, pitch angles, the centrifugal forces (along x-direction of the blade length), the cross-sectional forces (Fy and Fz) and the twisting moment of the blade (about the x-direction) were calculated for each of all the given time steps. After that the authors explain how to interpolate the calculated loadings (forces and twisting moment) and the right formulas to compute the aerodynamic load vector (the right side of the dynamic equations of motion).

A shear center demonstration model using 3D-printing

2021 ◽  
pp. 030641902110574
Author(s):  
Lawrence N Virgin
Keyword(s):  
3D Printing ◽  
Cross Section ◽  
Cross Sections ◽  
Principal Axis ◽  
Practical Importance ◽  
Bending Moment ◽  
Shear Center ◽  
Cross Sectional ◽  
Thin Walls ◽  
Section Profile

Locating the shear, or flexural, center of non-symmetric cross-sectional beams is a key element in the teaching of structural mechanics. That is, establishing the point on the plane of the cross-section where an applied load, generating a bending moment about a principal axis, results in uni-directional deflection, and no twisting. For example, in aerospace structures it is particularly important to assess the propensity of an airfoil section profile to resist bending and torsion under the action of aerodynamic forces. Cross-sections made of thin-walls, whether of open or closed form are of special practical importance and form the basis of the material in this paper. The advent of 3D-printing allows the development of tactile demonstration models based on non-trivial geometry and direct observation.

scholarly journals Assessment of Two-Equation Turbulence Models and Validation of the Performance Characteristics of an Experimental Wind Turbine by CFD

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Ece Sagol ◽  
Marcelo Reggio ◽  
Adrian Ilinca
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Wind Turbine ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Bending Moment ◽  
Mesh Size ◽  
Turbine Rotor ◽  
Cross Sectional ◽  
Wind Speeds

The very first step in the simulation of ice accretion on a wind turbine blade is the accurate prediction of the flow field around it and the performance of the turbine rotor. The paper addresses this prediction using RANS equations with a proper turbulence model. The numerical computation is performed using a commercial CFD code, and the results are validated using experimental data for the 3D flow field around the NREL Phase VI HAWT rotor. For the flow simulation, a rotating reference frame method, which calculates the flow properties as time-averaged quantities, has been used to reduce the time spent on the analysis. A basic grid convergence study is carried out to select the adequate mesh size. The two-equation turbulence models available in ANSYS FLUENT are compared for a 7 m/s wind speed, and the one that best represents the flow features is then used to determine moments on the turbine rotor at five wind speeds (7 m/s, 10 m/s, 15 m/s, 20 m/s, and 25 m/s). The results are validated against experimental data, in terms of shaft torque, bending moment, and pressure coefficients at certain spanwise locations. Streamlines over the cross-sectional airfoils have also been provided for the stall speed to illustrate the separation locations. In general, results have shown good agreement with the experimental data for prestall speeds.

scholarly journals Hemispheric Dominance and Laterality in Mobile Phone Use in Adults: An Observational Study

2019 ◽  
pp. 1-9
Author(s):  
N. C. Onyeagwara ◽  
A. L. Okhakhu
Keyword(s):  
Mobile Phone ◽  
Cell Phone ◽  
Phone Call ◽  
Hemispheric Dominance ◽  
Cross Sectional ◽  
Survey Tool ◽  
Mobile Phone Use ◽  
Phone Calls ◽  
Right Hand ◽  
The Right

Aims: Mobile/cell phone use has become an important socio-medical means of communication. The reason people use a particular ear to answer phone calls more frequently may be associated with hemispheric dominance/ handedness. We aim to determine association between hemispheric and or auditory dominance in laterality in mobile phone use.    Study Design:  This was a three month prospective cross-sectional study involving all consenting medical and paramedical respondents. Place and Duration of Study: Hospital community in the University of Benin Teaching Hospital (UBTH), Benin City , between 15th March to 15th June 2018. Method: A modification of the Edinburgh handedness inventory (EHI) was the survey tool. Information retrieved included social demographics, hand most commonly used for activities like writing and picking of phone calls and ear used for phone conversation and the reasons. Data was analyzed using SPSS 19.0 Results: Of the 300 questionnaires distributed, 234 (78%) were completed by the respondents. There were 120(51.3%) males and114 (48.7%) females.  Age ranged from 18 - 80years. A total of 201(85.9%) were right handed, 16(6.8%) left handed and 14(6.0%) ambidextrous. One hundred and fifty four (66%) routinely use their right hand to pick phone calls, 50(21.4%) left and 27 (11.5%) use both hands. A total of 141(60%) receive calls with the right ear, 60 (25.6%) with left, and 31(13.2%) had no preference.  Reasons advanced for the use of any particular ear included convenience 173 (73.9%), and better acuity 35(15%). Forty two (17.9%) agreed that the use of cell phone made them aware of their poor hearing in a particular ear. Using Pearson’s two tailed test of significance the probability of a right hander using the right hand to pick a phone call and placing it on the right ear is 0.99 or 99%, Vis a Vis left hander. Conclusion: There appears to be an association between hemispheric dominance and laterality when using the mobile phone.

scholarly journals Association of Digit Ratio With Depression and Hopelessness in Females

2021 ◽  
Vol 6 (3) ◽  
pp. 100-104
Author(s):  
Shabnam Aliabadi ◽  
Zahra Zendehboodi
Keyword(s):  
Severe Depression ◽  
Study Groups ◽  
Cross Sectional Study ◽  
Digit Ratio ◽  
Cross Sectional ◽  
Right Hand ◽  
Group 2 ◽  
Student’S T ◽  
The Right ◽  
Group 1

Introduction: Depression is regarded as the main cause of individual’s incapacity. One of the component of depression is hopelessness. This study was planned to examine if the digit ratio associates with depression and hopelessness status in the Iranian women. Methods: This cross-sectional study sample included 358 women aged between 20 to 32 years old. The palm side of both hands of individuals was photographed and then the length of index and ring fingers was measured by ImageJ. The Beck’s depression inventory II and Beck’s hopelessness scale (BHS) were used to measure the levels of depression and hopelessness respectively. ANOVA and Student’s t test was applied to compare the study groups in respect to the continuous data. Results: The results showed that the means of 2D:4D ratio of neither right nor left hands were significantly different between the depression study groups. The same insignificant results were derived with hopelessness status too. However, reanalyzing the data, while combination of depression and hopelessness was considered, showed a significantly lower digit ratio of the right hand in the women whit neither depression nor hopelessness (group 1) compared to the women with moderate/severe depression while holding a degree of hopelessness (group 2) (ratio mean for group 1: 0.978 ± 0.003 and for group 2: 0.992 ± 0.005; t = -2.417, P = 0.017). Conclusion: Our data suggested that the 2D:4D ratio of the right hand in the women associates with the severity of depression when accompanied by hopelessness.

Analysis of Lateral Torsional Buckling Strength of Single Symmetric I Beam

2020 ◽  
Vol 846 ◽  
pp. 226-231
Author(s):  
Wei Hsun Hsu ◽  
Yu Xin Liu ◽  
Kun Ze Ho ◽  
Wei Ting Hsu
Keyword(s):  
Cross Sections ◽  
Bending Moment ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cross Sectional ◽  
Buckling Strength ◽  
Difference Analysis ◽  
Beam Design ◽  
Plastic Phase ◽  
Strength Difference

This study evaluates the variation of the bending moment strength of the single symmetrical and double symmetrical I-beam design. This study compares the use of a double-symmetric I-section with a large, small flange, a single-symmetric I-section with a large compression and large tension flange. The study shows that the four sections have the largest wing strength with double-symmetric I-section, and the inelastic and elastic strengths are similar to those of the single-symmetric I-section, especially the elastic region is almost the same. In the plastic phase, the double symmetrical flanges have a high cross-sectional strength. In the inelastic phase, the intensity of two individual symmetrical sections of the same area is close to a double symmetrical section. The use of a single symmetrical I-beam can be preferred over a double-symmetric I-beam. This study provides a single-symmetric I-beam strength difference analysis, providing users with a variety of options for comparing cross-sections.

Cross-Sectional Study of Minutiae Patterns in Bini Ethnic Group of Southern Nigeria

2020 ◽  
Author(s):  
Fariha Azalea
Keyword(s):  
Informed Consent ◽  
Ethnic Group ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Left Hand ◽  
Right Hand ◽  
Southern Nigeria ◽  
The Right ◽  
Level 2

Background: This study was aimed at evaluating the minutiae patterns in of Bini ethnic group of Southern Nigeria. The study was descriptive and cross-sectional with volunteers age ranging from 18-60 years. For the purpose of this study, an individual was considered to be a Nigeria of a particular ethnic group if the parents and four grandparents are of the same ethnic group. Materials and Methods: Purposive sampling method was used for the study. The selection and collection of required parameters relied on informed consent of volunteer subjects. This was done by giving them a copy of the informed consent letter which was signed and dated. A total of 400 subjects (Males 225, Females 175) were recruited for the study. The fingerprints were obtained using print scanner (Hp G3110 Photo scanner) following Oghenemavwe and Osaat (2015) improvised model. Results and Discussion: Distribution of total digital patterns in Bini showed that on the left hand they had the following: Ridge Ending 4399(17.1%), Ridge Crossing 2335 (9.0%), Bridge 1979(7.7%), Lake 2077(8.1%), Bifurcation 5283(20.5%), Double Bifurcation 2021 (7.8%), Dot 2015 (7.8%), Trifurcation 1938 (7.5%), Opposed Bifurcation 2029 (7.9%), Island 1723 (6.6%), while on the right hand the distributions were: Ridge Ending 4415 (17.2%), Ridge Crossing 2323 (9.0%), Bridge 1999(7.7%), Lake 2065(8.0%), Bifurcation 5303(20.6%), Double Bifurcation 2005 (7.7%), Dot 2025 (7.8%), Trifurcation 1915 (7.4%), Opposed Bifurcation 2044 (7.9%), Island 1709 (6.7%). Conclusion: The descriptive cross-sectional study of minutiae pattern has revealed the following trend of patterns: Bifurcation 5283 (20.5%) > Ridge ending 4399(17.1%) > Ridge crossing 2335 (9.0%) on the left whereas on the right hand thus: Bifurcation 5303(20.6%) > Ridge ending 4415 (17.2%) > Ridge crossing 2323 (9.0%). This trend is in line with the stated trends for Africa, this study provides a baseline data on level 2 patterns or minutiae for the Bini people of Southern Nigeria.

scholarly journals Morphofunctional Features of the Thyroid Mast Cell Histotopography under Motor Activity

2021 ◽  
Vol 10 (4) ◽  
pp. 19-27
Author(s):  
A. V. Bezdenezhnykh ◽  
M. S. Aryasov
Keyword(s):  
Thyroid Gland ◽  
Optical Density ◽  
Cross Sections ◽  
Central Zone ◽  
Cross Sectional ◽  
Functional Changes ◽  
Average Optical Density ◽  
Wide Range ◽  
The Right ◽  
Adaptation Processes

Dysfunction and pathology of the thyroid gland (TG) are inextricably related to structural and functional changes in the organ. It is known that the stroma of the thyroid gland contains mast cells (MCs) participating in adaptation processes.The aim of research was to study morphofunctional changes in MCs in various topographic zones of the canine thyroid gland in normal conditions and under muscular loads that cause structural transformations of the organ.Material and methods. The study involved digitized cross-sections of the central part of the right thyroid lobe of male dogs, aged 1.5 to 2 years. The animals were divided into the control (n = 16) and experimental groups (n = 67); they received single and multiple starting, training, extreme dynamic muscular loads with the heart rate control. MCs were detected using azure-eosin staining. Based on the results of the qualitative analysis, the histoscore coefficient was calculated. In the ImageJ program, the area of MCs and their average optical density were measured relative to the geometric center of the section in the central, intermediate and peripheral zones.Results. Muscle loads during single and multiple trainings resulted in a stereotyped MC response: a decrease (p <0.008) in their number, cross-sectional area, average optical density, and histoscore coefficient. The duration and frequency of exposure formed a wide range of responses, up to atypical. Involvement of the central zone was detected in 100% of cases, intermediate in 2/3 of cases and peripheral in 50%.Conclusion. MCs provide integration in the central, intermediate and peripheral zones of the thyroid gland, and the magnitude and frequency of impacts determine the severity and specificity of their morphofunctional changes.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

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