Non-Linear Modeling of Ocean Current Turbine Blades Under Large Deflection

2016 ◽  
Author(s):  
Takuya Suzuki ◽  
Hassan Mahfuz
Keyword(s):  
Large Scale ◽  
Large Deflection ◽  
Turbine Blades ◽  
Structural Response ◽  
Ocean Current ◽  
Hydrodynamic Load ◽  
Linear Modeling ◽  
Non Linear ◽  
The Difference ◽  
Current Turbine

This paper presents a non-linear modeling approach for large-scale ocean current turbine (OCT) blades. During the operation, OCT blades are subjected to a hydrodynamic load that has fluid density 800 times higher than that of air. The fluid load on OCT blades are sufficient to cause large deflection; therefore, a method that couples the blade’s deflection and the hydrodynamic load is required. For this purpose, we developed a non-linear model for turbine blades based on blade element momentum (BEM) theory. The newly developed method considers interplay between blade’s deflection and the hydrodynamic load. In addition, geometric non-linearity is also considered in the analysis, which provides a more accurate prediction of the structural response. For validation purposes, the developed method and a set of existing National Renewable Energy Laboratory (NREL) codes were used to calculate the deflection of the OCT blade. A comparison of flap-wise and edge-wise deflections given by both methods were determined and the results showed a good correlation between the two methods. This comparison was made only for small deflection since NREL codes cannot account for large deflection. In the next step, to investigate the effect of non-linearity, both linear and non-linear analyses were performed for a large-scale OCT blade where deflection was indeed large. In this study, we analyzed a flexible blade made of E-glass/epoxy composite. The difference in deflection was about 11% for the flexible blade since the fluid-structure interaction was significant as the blade deflection was large.

Design and Analysis of Composite Ocean Current Turbine Blades Using NREL Codes

2012 ◽  
Author(s):  
Fang Zhou ◽  
Hassan Mahfuz ◽  
Gabriel M. Alsenas ◽  
Howard P. Hanson
Keyword(s):  
Wind Turbine ◽  
Stress Analysis ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Core Material ◽  
Ocean Current ◽  
Wind Turbine Blades ◽  
Lift And Drag ◽  
Current Turbine ◽  
Core Materials

Ocean current energy is at an early stage of development — a vital component in that is the design and analysis of turbine blades that would be used to generate the power. The ocean current turbine (OCT) is similar in function to wind turbines, capturing energy through the processes of hydrodynamic, rather than aerodynamic, lift or drag. OCT operates on many of the same principles as wind turbines and share similar design philosophies. NREL (National Renewable Energy Laboratory) has extensively investigated the design of wind turbine blades over the years and many codes have been developed. It is meaningful and prudent to take advantage of those codes and use them in the design of OCT blades. Currently available codes such as FoilCheck, PreComp, BModes, AeroDyn, FAST, etc. provides an excellent dynamic analysis of hollow composite wind turbine blades. Since OCT blades have PVC foam as core materials inside the skin, NREL codes could not be used directly. These core materials for the blade were necessary to fulfill the buoyancy requirement at ocean depth. A set of methods was therefore developed to design and analyze OCT blades where most of NREL codes could be utilized. The methods are as follows: DesignFOIL was first used to generate hydrofoil geometry (coordinates), and lift and drag coefficients for selected blade sections. FoilCheck was then used to calculate hydrofoil data for the entire range of ±180°. FoilCheck output files were later used as input for AeroDyn. In the next step, PreComp computed the section properties for the hollow composite OCT blade. Section properties of the core material such as extensional stiffness, flexural rigidity, and torsional rigidity were calculated separately and added to the properties computed by PreComp. Mode shapes and frequencies of OCT blades were computed using BModes. AeroDyn calculated the hydrodynamic lift and drag forces for the hydrofoil sections along the blade. In AeroDyn input file, kinematic viscosity, density and velocity were set to the values of seawater @ 1.05×10−6 m2/sec, 1025 kg/m3, and 1.7 m/s, respectively. Finally, FAST was used to obtain the dynamic response of three-bladed, conventional, horizontal-axis OCT. However, this analysis did not provide any stress calculations. In order to perform stress analysis, NuMAD code developed by Sandia National Laboratory was incorporated in the method. This allowed us to create ANSYS input files. Loads calculated by AeroDyn were then transported to ANSYS and a complete stress analysis was performed. Critical regions of stress concentration were identified — opening up an opportunity for materials failure and fatigue analysis. In summary, coupling of NREL codes, NuMAD, and ANSYS revealed a path way to achieve comprehensive design and analyses of OCT blades.

scholarly journals The Analysis of the Aerodynamic Character and Structural Response of Large-Scale Wind Turbine Blades

Energies ◽  
2013 ◽  
Vol 6 (7) ◽  
pp. 3134-3148 ◽  
Author(s):  
Xin Cai ◽  
Pan Pan ◽  
Jie Zhu ◽  
Rongrong Gu
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Turbine Blades ◽  
Structural Response ◽  
Wind Turbine Blades

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

TO THE PROBLEMS OF COMBATING CORRUPTION IN MODERN RUSSIA AND INTERNATIONAL COOPERATION IN THE FIELD OF ANTI-CORRUPTION

2020 ◽  
Author(s):  
Angela Dranishnikova
Keyword(s):  
Large Scale ◽  
The State ◽  
Point Of View ◽  
Modern Life ◽  
Existing Problems ◽  
Moral Point ◽  
Material Goods ◽  
The Russian Federation ◽  
The Difference ◽  
The Government

In the article, the author reflects the existing problems of the fight against corruption in the Russian Federation. He focuses on the opacity of the work of state bodies, leading to an increase in bribery and corruption. The topic we have chosen is socially exciting in our days, since its significance is growing on a large scale at all levels of the investigated aspect of our modern life. Democratic institutions are being jeopardized, the difference in the position of social strata of society in society’s access to material goods is growing, and the state of society is suffering from the moral point of view, citizens are losing confidence in the government, and in the top officials of the state.

scholarly journals Large-Scale Analysis of the Spatiotemporal Changes of Net Ecosystem Production in Hindu Kush Himalayan Region

2021 ◽  
Vol 13 (6) ◽  
pp. 1180
Author(s):  
Da Guo ◽  
Xiaoning Song ◽  
Ronghai Hu ◽  
Xinming Zhu ◽  
Yazhen Jiang ◽  
...  
Keyword(s):  
Large Scale ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Carbon Sources ◽  
Spatial Dynamics ◽  
Tibet Plateau ◽  
Geostatistical Model ◽  
Hindu Kush ◽  
Temporal And Spatial ◽  
The Difference

The Hindu Kush Himalayan (HKH) region is one of the most ecologically vulnerable regions in the world. Several studies have been conducted on the dynamic changes of grassland in the HKH region, but few have considered grassland net ecosystem productivity (NEP). In this study, we quantitatively analyzed the temporal and spatial changes of NEP magnitude and the influence of climate factors on the HKH region from 2001 to 2018. The NEP magnitude was obtained by calculating the difference between the net primary production (NPP) estimated by the Carnegie–Ames Stanford Approach (CASA) model and the heterotrophic respiration (Rh) estimated by the geostatistical model. The results showed that the grassland ecosystem in the HKH region exhibited weak net carbon uptake with NEP values of 42.03 gC∙m−2∙yr−1, and the total net carbon sequestration was 0.077 Pg C. The distribution of NEP gradually increased from west to east, and in the Qinghai–Tibet Plateau, it gradually increased from northwest to southeast. The grassland carbon sources and sinks differed at different altitudes. The grassland was a carbon sink at 3000–5000 m, while grasslands below 3000 m and above 5000 m were carbon sources. Grassland NEP exhibited the strongest correlation with precipitation, and it had a lagging effect on precipitation. The correlation between NEP and the precipitation of the previous year was stronger than that of the current year. NEP was negatively correlated with temperature but not with solar radiation. The study of the temporal and spatial dynamics of NEP in the HKH region can provide a theoretical basis to help herders balance grazing and forage.

scholarly journals Can Mandatory Disclosure Policies Promote Corporate Environmental Responsibility?—Quasi-Natural Experimental Research on China

2021 ◽  
Vol 18 (11) ◽  
pp. 6033
Author(s):  
Yue Liu ◽  
Pierre Failler ◽  
Liming Chen
Keyword(s):  
Property Rights ◽  
Large Scale ◽  
Environmental Responsibility ◽  
Mandatory Disclosure ◽  
Corporate Environmental Responsibility ◽  
Disclosure Policy ◽  
Protection Information ◽  
The Difference ◽  
Csr Disclosure ◽  
Corporate Social

Corporate environmental responsibility (CER) is an important component of the corporate social responsibility (CSR) report, and an important carrier for enterprises to disclose environmental protection information. Based on the corporate micro data, this paper evaluates the effect of a mandatory CSR disclosure policy on the fulfillment of corporate environmental responsibility by adopting the difference-in-differences model (DID) with the release of a mandatory disclosure policy of China in 2008 as a quasi-natural experiment. The study draws the following conclusions: First, a mandatory CSR disclosure policy can promote the fulfillment of CER. Second, after the implementation of a mandatory CSR disclosure policy, enterprises can improve their CER level through two channels: improving the quality of environmental management disclosure and increasing the number of patents. Third, the heterogeneity of the impacts of mandatory CSR disclosure on CER is reflected in three aspects: different CER levels, different corporate scales and a different property rights structure. In terms of the CER level, there is an inverted U-shaped relationship between the CER level and mandatory CSR disclosure effect. In terms of the corporate scale, mandatory disclosure of CSR plays a greater role in large-scale enterprises. In terms of the structure of property rights, mandatory CSR disclosure has a greater effect on non-state-owned enterprises.

scholarly journals Investigating the properties of a galaxy group at z = 0.6

2020 ◽  
Vol 15 (S359) ◽  
pp. 188-189
Author(s):  
Daniela Hiromi Okido ◽  
Cristina Furlanetto ◽  
Marina Trevisan ◽  
Mônica Tergolina
Keyword(s):  
Large Scale ◽  
The Other ◽  
Numerical Density ◽  
Spectroscopy Data ◽  
Stellar Kinematics ◽  
Galaxy Groups ◽  
The Galaxy ◽  
The Difference ◽  
The Impact ◽  
The Universe

AbstractGalaxy groups offer an important perspective on how the large-scale structure of the Universe has formed and evolved, being great laboratories to study the impact of the environment on the evolution of galaxies. We aim to investigate the properties of a galaxy group that is gravitationally lensing HELMS18, a submillimeter galaxy at z = 2.39. We obtained multi-object spectroscopy data using Gemini-GMOS to investigate the stellar kinematics of the central galaxies, determine its members and obtain the mass, radius and the numerical density profile of this group. Our final goal is to build a complete description of this galaxy group. In this work we present an analysis of its two central galaxies: one is an active galaxy with z = 0.59852 ± 0.00007, while the other is a passive galaxy with z = 0.6027 ± 0.0002. Furthermore, the difference between the redshifts obtained using emission and absorption lines indicates an outflow of gas with velocity v = 278.0 ± 34.3 km/s relative to the galaxy.

First models for structural energy transmission decoupling in the high frequency regime under aerodynamic excitations

2021 ◽  
pp. 095440622110200
Author(s):  
G Mazzeo ◽  
MN Ichchou ◽  
G Petrone ◽  
O Bareille ◽  
S De Rosa ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Vibrational Energy ◽  
Complex Structure ◽  
Structural Response ◽  
Test Case ◽  
Analysis Model ◽  
Quick Method ◽  
Vibrational Velocity ◽  
Frequency Regime ◽  
The Difference

In the wind tunnel facility, a test structure is often used for measuring its vibrational response to the aerodynamic excitation. A support is needed to sustaining the structure and it is mandatory that this support does not influence the vibrational energy to be measured. To this aim, the maximum amount of energy decoupling between the structure and the support is desired. This work is focused around a quick method to estimate this decoupling by using simplified models for the Turbulent Boundary Layer (TBL) excitation and for the structural response. Specifically, the Equivalent Rain-on-the-roof excitation is invoked with a Statistical Energy Analysis model for the structure. Some simple design rules are proposed and based on little information leading to foresee the difference of vibrational velocity levels between the two structural systems. A simplified test-case is used for the first investigations and a complex structure is finally conceived thinking to vibroacoustic measurements in a large wind tunnel facility. Although some results are largely expected, the global approach is promising.

scholarly journals Grounding semantic transparency in context

Morphology ◽  
2021 ◽  
Author(s):  
Rossella Varvara ◽  
Gabriella Lapesa ◽  
Sebastian Padó
Keyword(s):  
Large Scale ◽  
Point Of View ◽  
Distributional Semantics ◽  
Semantic Transparency ◽  
Inclusion Measure ◽  
The Difference ◽  
Semantic Point ◽  
The Many ◽  
The Relationship

AbstractWe present the results of a large-scale corpus-based comparison of two German event nominalization patterns: deverbal nouns in -ung (e.g., die Evaluierung, ‘the evaluation’) and nominal infinitives (e.g., das Evaluieren, ‘the evaluating’). Among the many available event nominalization patterns for German, we selected these two because they are both highly productive and challenging from the semantic point of view. Both patterns are known to keep a tight relation with the event denoted by the base verb, but with different nuances. Our study targets a better understanding of the differences in their semantic import.The key notion of our comparison is that of semantic transparency, and we propose a usage-based characterization of the relationship between derived nominals and their bases. Using methods from distributional semantics, we bring to bear two concrete measures of transparency which highlight different nuances: the first one, cosine, detects nominalizations which are semantically similar to their bases; the second one, distributional inclusion, detects nominalizations which are used in a subset of the contexts of the base verb. We find that only the inclusion measure helps in characterizing the difference between the two types of nominalizations, in relation with the traditionally considered variable of relative frequency (Hay, 2001). Finally, the distributional analysis allows us to frame our comparison in the broader coordinates of the inflection vs. derivation cline.

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