bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conceptual monopile and tower sizing for the IEA Wind Task 37 Borssele reference wind farm
Authors: McWilliam Michael K. , Natarajan Anand , Pollini Nicolo , Dykes Katherine , Barter Garrett E. 
Published: September 2021

Abstract
This paper explores the preliminary design of the support structures for the IEA Wind Task 37 reference wind farm at the Borssele site III and IV. The study looks at two different design methods that might be used within larger wind farm system design optimization (i.e. lay-out, electrical systems, etc.). The first consists of a scaling tool that scales a detailed design according to the rated power, water depth, hub height and rotor diameter. The second is a physics-based optimization approach that relies on the WISDEM® design tool. This research compares the results of these two methods for the design of both the tower and monopile of the IEA 10-MW and 15-MW reference wind turbines at a range of sea depths (25 m, 30 m, 35 m, 40 m). The two tools yield very similar results in terms of monopile base diameter, support structure natural frequency and mass. WISDEM is then used to also investigate the sensitivity of the design to the tower top forces, wave conditions and the soil conditions. It is shown that tower top forces dominate the design. In general, large diameter structures can carry additional costs associated with manufacturing and transportation requirements. Thus, the paper is concluded with a trade-off study between mass and diameter that quantifies the effect of the reduction in monopile diameter with the increase in structural mass.
A hierarchical supervisory wind power plant controller
Authors: Merz Karl , Chabaud Valentin , Garcia-Rosa Paula B. , Kolle Konstanze 
Published: September 2021

Abstract
The operation of future wind power plants (WPPs) will rely on maximizing overall profit rather than power production. Factors like current electricity price, grid code compliance, and maintenance costs will affect operational decision. Therefore, it is expected that plant control strategies will trade different control objectives while respecting the industrial practice, where the different levels in the hierarchy may be provided by different equipment vendors. This work proposes a plant controller that aims to track an operator power command at the WPP level and to reject low-frequency loading due to turbulent winds at individual turbines. The plant control respects the hierarchy in which the turbine-level controller takes precedence, interacting only via power set-point commands to each turbine. The control algorithm is based on parallel control loops along with look-up tables and gain scheduling, and its simplicity and effectiveness make it well-suited for industrial applications. Preliminary simulation results with a 32-turbine WPP indicate that there is a significant synergy effect by coordinating operation of the turbines in a plant. Structural loads can be reduced on certain turbines without excessively burdening the others, while an accurate plant-wide power tracking is still provided.
Analysis of offshore wind spectra and coherence under neutral stability condition using the two LES models PALM and SOWFA
Authors: Ning X , Krutova M , Bakhoday-Paskyabi M 
Published: September 2021

Abstract
The Parallelized Large-Eddy Model (PALM) and the Simulator for Wind Farm Applications (SOWFA) have been used to simulate the marine boundary layer flows under neutral stability condition. The present work aims to investigate the capability of the two models in reproducing the structure of turbulence in the offshore environment through comparative analysis with a focus on wind spectra and coherence. Wind spectra obtained from the two LES solvers agree well with the empirical spectral model near the surface but show lower turbulence intensity in the low frequency range above the surface layer. Both models also produce highly consistent estimates of coherence with different horizontal and vertical separations, which match well with Davenport and IEC coherence models at height of 180m and 140m respectively. As the height decreases, LES predicts lower vertical coherence compared with the IEC model and the fitted decay coefficient for Davenport model grows as the separation distance increases.
Analysis of turbulence models fitted to site, and their impact on the response of a bottom-fixed wind turbine
Authors: Nybø A , Nielsen FG , Godvik M 
Published: September 2021

Abstract
This study compares a wind field recommended by the wind turbine design standards to more realistic wind fields based on measurements. The widely used Mann spectral tensor model with inputs recommended by the standard, is compared to FitMann, the Mann model with inputs fitted to measurements and TIMESR; using measured time series combined with the Davenport coherence model. The Mann model produces too low energy levels at the lowest frequencies of the wind spectra, while the wind spectra generated by FitMann approaches the measured values. TIMESR reproduces the measured spectral values at all frequencies. The different models give similar vertical coherence, while the Mann and FitMann models give lower horizontal coherence than TIMESR. Investigating the wind loads on a bottom-fixed 10-MW wind turbine, the spectra for the tower bottom fore-aft and blade root flapwise bending moment follow the shape of the wind spectra closely at low frequencies. The low-frequency range is important for the blade root and in particular the tower bottom bending moment. Thus, the TIMESR model, followed by FitMann, is assumed to give the most accurate fatigue estimates. For the specific situation analysed in this study, the FitMann model gives only 18 and 5 % lower estimates than TIMESR of the tower bottom and blade root damage equivalent bending moments, while the Mann model gives 27 % and 12 % lower estimates. The tower top yaw and fore-aft bending moments depend on the wind coherence. For the specific situation analysed in this study, the FitMann model gives 9 and 5 % higher estimates of the tower top yaw and tower top damage equivalent (bending) moments compared to TIMESR, while the Mann model gives 23 % and 18 % higher estimates. Since only measurements of the vertical coherence are available, it is not clear which model is superior for the tower top moments. However, the importance of a proper coherence model is documented.
Hybrid analysis and modeling for next generation of digital twins
Authors: Pawar Suraj , Ahmed Shady E. , San Omer , Rasheed Adil 
Published: September 2021

Abstract
The physics-based modeling has been the workhorse for many decades in many scientific and engineering applications ranging from wind power, weather forecasting, and aircraft design. Recently, data-driven models are increasingly becoming popular in many branches of science and engineering due to their non-intrusive nature (i.e., they are equation-free) and online learning capability. Despite the robust performance of data-driven models, they are faced with challenges of poor generalizability and difficulty in interpretation. These challenges have encouraged the integration of physics-based models with data-driven models, herein denoted hybrid analysis and modeling (HAM). We propose two different frameworks under the HAM paradigm for applications relevant to wind energy in order to bring the physical realism within emerging digital twin technologies. The physics-guided machine learning (PGML) framework reduces the uncertainty of neural network predictions by embedding physics-based features from a simplified model at intermediate layers and its performance is demonstrated for the aerodynamic force prediction task. Our results show that the proposed PGML framework achieves approximately 75% reduction in uncertainty for smaller angle of attacks. The interface learning (IL) framework illustrates how different solvers can be coupled to produce a multifidelity model and is successfully applied for the Boussinesq equations that govern a broad class of transport processes. The IL approach paves the way for seamless integration of multi-scale, multi-physics and multi-fidelity models (M
3 models).
Direct and fast probabilistic assessment of long term monopile load distribution from combined metocean data and fully nonlinear wave kinematics
Authors: Tornfeldt Sørensen J V , Hansen H F , Mandviwalla X , Pierella F , Bredmose H 
Published: September 2021

Abstract
A novel method is introduced to determine the long-term extreme value distribution of variables with an associated short-term distribution. The method is applicable to e.g. the extreme value with a return period of 10.000 years for wave height, crest height of waves as well as wave-induced response and loads on offshore wind turbine monopiles. The extreme values are determined by a combination of a joint probabilistic description of the met-ocean environment and of a recently developed database of fully nonlinear wave kinematics computations. For two benchmark monopile structures, representative for the conditions at Dogger Bank and the German Bight in the North Sea, the one-hour max value of crest height, inline force and overturning moment are computed via the Rainey slender-body force model. Convolution with the joint probability of the sea state parameters in the nondimensional space of wave steepness and Ursell parameter leads to the marginal probability distribution for these parameters up to a 10.000 year return period and properly accounts for the uncertainty of the extreme value parameters in also the short-term distributions. It is found that the best extreme value fit is generally obtained with a third-order polynomial fit within the space of steepness and Ursell parameter. Compared to the Forristall crest height distribution, the inclusion of full nonlinearity leads to larger crest heights at low return period levels. However, due to its realistic treatment of the breaking limitation, lower crests are predicted at the 10.000 year level for the two positions considered in the North Sea. With further verification of the wave kinematics in combination with load models and a thorough comparison to present engineering practice, the proposed methodology provides a robust future solution for directly estimating extreme value distributions of loads and response of offshore wind turbine monopiles.
A non-intrusive parametric reduced order model for urban wind flow using deep learning and Grassmann manifold.
Authors: Tabib Mandar V , Pawar Suraj , Ahmed Shady E. , Rasheed Adil , San Omer 
Published: September 2021

Abstract
In this study, we present a parametric non-intrusive reduced order modeling framework as a potential digital twin enabler for fluid flow related applications. The case study considered here involves building-induced flows and turbulence with inlet turbulence value as a parameter. The framework proposed employs a Grassmann manifold interpolation approach (GI) for obtaining basis functions corresponding to new values of parameter, and exploits the time series prediction capability of long short-term memory (LSTM) recurrent neural network for obtaining temporal coefficients associated with the new basis functions. The methodology works in the following way: (i) in the training phase, the LSTM model is trained on the modal coefficients extracted from the high-resolution data using proper orthogonal decomposition (POD) transform for the known values of parameter, and (ii) in the testing phase, the trained model predicts the modal coefficients for the total time recursively based on the initial time history for the new value of parameter. Then, we reconstruct the flow fields for the new value of parameter (new inlet turbulent value) using the GI modulated basis functions and LSTM predicted associated temporal coefficients. To assess the performance of the proposed model, the ROM-LG predictions are compared with the high-dimensional full-order model solutions using L1 and L2 error analyses as well as with the conventional POD based ROM (ROM-POD) solutions. The results indicate that the non-intrusive ROM (ROM-LG) framework yields a stable solution for the velocity fields and for short-term prediction of dynamic turbulent kinetic energy fields. This work has scope for further development and will be useful for building-integrated wind energy and urban drone operation in a smart-city digital twin platform.
Reduced order models for finite-volume simulations of turbulent flow around wind-turbine blades.
Authors: Tsiolakis Vasileios , Kvamsdal Trond , Rasheed Adil , Fonn Eivind , Brummelen Harald van 
Published: September 2021

Abstract
The computational cost of the design optimisation of wind turbines, as well as the optimisation of the operation and maintenance of offshore wind farms represents a limitation to the application of conventional simulation methods. New techniques such as reduced order modelling (ROM) and technologies such as hybrid-analysis methods and digital twins have increased in popularity due to their ability to deliver numerical results at a significant speed-up with reasonable accuracy. This work presents a hybrid projection-based proper orthogonal decomposition (POD) strategy applied to transient turbulent flow problems. Key feature of this work is the applicability of the methodology to high Reynolds number cases and the stabilisation of pressure in the online phase via the assembly of the so-called pressure Poisson equation. Another significant part of this work is the implementation of an interpolation scheme for the eddy viscosity field in the classical POD-Galerkin strategy. The sampling procedure and the calculation of the reduced operators in the offline phase is carried out using the finite volume method (FVM), OpenFOAM’s libraries specifically, while the construction of the reduced basis and the solution of the online phase is carried out in Python. The capability of the resulting ROM is tested using the two-dimensional flow around a NACA0015 airfoil at 17° angle of attack with Reynolds number of approximately 300 000.
Preliminary assessment of yaw alignment on a single point moored downwind floating platform
Authors: Urbán Albert M. , Voltà Laura , Lio W. H. , Torres Rocio 
Published: September 2021

Abstract
The ability of Single Point Moored Downwind platforms to align with the main wind direction, depends on the floater and wind turbine design. When co-directionality between wind, waves and current exists, there is no external loading that can difficult the floater alignment. On the other hand, when certain metocean conditions take place, such as a crosscurrent, a misaligning force can prevent the floater to face towards the main wind direction.
In this study, the PivotBuoy floater is used to evaluate the Single Point Moored platform’s ability to align with the main wind direction. The platform dynamics are assessed under irregular wind and wave conditions for current speeds ranging from 0.1 m/s to 1.5 m/s for different wind-current alignments. Two solutions for improving the platform alignment are presented and compared against the baseline case, for the extreme and unusual condition where the platform is operating with a crosscurrent of 90° and 0.4 m/s. Both proposed strategies, an active, based on Individual Pitch Control, and a passive where a static nacelle yaw offset is used, are able to reduce the mean alignment to be within 0.8° compared to the baseline case of 18.7°. The preliminary analysis show promising results for the proposed solutions but need to be further investigated in detail.
Study on the feasibility of applying DNA molecular marking technology to anti-counterfeiting of artifacts and artworks
Authors: Wu H C , Chu W S , Li I C , Wang H L , Huang B W 
Published: September 2021

Abstract
Artifacts and artworks record the wisdom of human activities and civilization. They not only trace an era’s history or reflect the aesthetics of contemporary art and different lifestyles, but they also enable us to understand the codes of wisdom passed down from our ancestors and explore history. Therefore, determining artworks’ authenticity is increasingly important. The objective of study was to investigate the feasibility of applying DNA molecular marking technology to anti-counterfeiting of artifacts and artworks. The DNA sequence used for testing in this research came from the team’s previous studies. A genetic substance was embedded in the artwork to test the DNA’s feasibility, repeatability, and reproducibility, as well as the difference in the deterioration conditions of the DNA embedded artwork. Our results showed that about 70% to 90% of the DNA fragments remained intact. Therefore, we conclude that embedding the extracted DNA directly into a painting and detecting whether the DNA fragments persist after reconstitution could help us to determine the authenticity of a painting
Tracking control of a precision stage with NARX neural network for friction compensation
Authors: Irfanda I T , Shen J C 
Published: September 2021

Abstract
The objective of this study is to develop a neural network controller for the friction compensation. The purpose models are used as an inverse model of the frictional force and dynamic behaviour of a system. A proportional-integral-derivative (PID) controller and a neural network system architecture are developed for the Nonlinear Autoregressive with Exogenous inputs (NARX) neural network were proposed to control a precision stage. Firstly, a test signal was used to drive the stage then the derived data was used to train a NARX neural network. This neural network model is the inverse dynamic model of the stages and friction force. An architectural approach of NARX showing promising qualities for dynamic system applications, is analysed in this paper. Utilization of this model is as an estimate of the driving force related with the dynamics of the system against displacement, and is then used as a feed-forward controller to compensate for friction errors. Finally, the experimental systems are established and the result shows that the combination of PID and NARX can improve the tracking performance of the precision stage.
Applying cyber physical system architecture concept to the design and manufacturing of blood glucose monitoring systems to provide man-machine interactions and intelligent automation
Authors: Kuo H Y , Chang H , Cheng Y H , Shaw J S , Lee R 
Published: September 2021

Abstract
The current design and manufacturing of blood glucose monitoring systems (BGMS) cannot resolve many current problems. Even with recent new advances on 100% non-damaging quality check and laser repair for the defective test strips found, it is still not enough. With the new internet, a new revolutionary architectural concept based on cyber physical system (CPS) is highly recommended to implement on the design and manufacturing of BGMS. This paper presents many unique benefits that can be achieved. The implementation of CPS to the design of BGMS interconnects the uses of glucose meters, test strips and control solutions with the manufacturing systems through internet to enhance the safety and performance of the BGMS, and to provide man-machine interactions and intelligent automation. Furthermore, the implementation of CPS to the manufacturing of BGMS further interconnects sensors and information feedbacks from different work stations to allow the manufacturing systems to be self-aware, self-adaptable and self-configurable, in order to reduce manpower, defective rate and production down time for better productivity. This new concept will bring in revolutionary approaches into the design and manufacturing of BGMS, in order to upgrade product performance, increase product competitiveness and create new business opportunities, by providing man-machine interactions and intelligent automation. Apart from that, the implementation of CPS architecture to the design and manufacturing of BGMS does not necessarily increase the costs of producing BGMS.
Finite element analysis of cold drawing of stainless steel bars
Authors: Hwang Y M , Lin M R , Wu C H , Tsui H S R 
Published: September 2021

Abstract
Drawing is a metal forming process that is carried out by pulling a work piece through a die cavity. During the process, the cross-sectional area of the work piece reduces and the shape of the product is the same as that of the die cavity. In traditional industries, the required accuracy and quality can be achieved through multiple tryouts, by which a large amount of testing samples and time are required and accordingly results in the increase in production cost and decrease in productivity. Cold drawing is an effective way to produce bars or wires with high precision in product size. However, there is still no appropriate quantitative formula to determine how the dimensions of the die and the forming parameters affect the geometric dimensions of the product. In recent years, the progress of simulation technology allows us to investigate the effects of forming parameters on finished products dimensions. However, there was no literature discussing the effects of various parameters on the precision of the product dimensions. In this paper a finite element model is established to analyze the elastoplastic deformation of the bar inside the die cavity. An empirical formula including various forming parameters is established from a series of simulation results, and the precision can reach within 0.1%.
Study on the characteristics of the materials and manufacturing quality to shrapnel-type couplings properties
Authors: Chen C M , Chang H L , Lin C C 
Published: September 2021

Abstract
With the development and application for the ultra-precision machinery industries and smart machinery have become prosperous. The precision transmission sub-system is an important part of the precision machinery equipment and smart machinery industries. Then shrapnel-type coupling is an important part of the precision transmission system. In the shrapnel-type couplings with high precision, high reliability, and high efficiency. The design of shrapnel-type couplings needs to correct and improved in the manufacturing with very high-precision inspection equipment, and expert measurement technology. The high quality of shrapnel-type couplings, materials and manufacturing qualities are the main factor for high precision, high reliability, and high efficiency. This paper will be a depth study of the body materials and manufacturing qualities of shrapnel-type couplings. The inner hole contact surfaces of the shrapnel-type couplings to connect between each other connecter tested the properties of the coupling via toque-torque angle testing equipment with changing the shrapnel-type couplings body materials and manufacturing different roughness of inner hole. The key characteristics that affect the torsional rigidity and failure torque of the coupling grasped are found out using the self-developed toque-twist angle testing machine. The body of the shrapnel-type couplings made with 7075 aluminium alloy and 6061 aluminium alloy. Through experiments, we can understand the influence of different materials bodies on the torsional rigidity and failure moment of the shrapnel-type couplings. From experimental results, that 7075 aluminium alloy is better than 6061 aluminium alloy of torsional rigidity or failure moment. As the inner hole surface roughness of the shrapnel-type couplings smaller has a higher failure torque of coupling.