Browse Topic: Wind power

Items (210)
This study investigates the unsteady aerodynamic response, wake evolution, and vortex dynamics of an ultra-large floating offshore wind turbine (FOWT) under coupled motion–wave conditions. A high-fidelity aero–hydrodynamic CFD model is employed for the IEA 22 MW reference turbine. Platform pitch and surge motions are prescribed via sinusoidal functions, and wave conditions are independently introduced by considering two representative sea states (H = 4 m and 7 m) and a no-wave case. Results show that pitch and combined pitch–surge motions significantly amplify unsteady aerodynamic effects, increasing peak power from 81.1 MW (P5S0) to 92.6 MW (P5S5), with periodic negative power output and severe dynamic stall. Under strong motion, waves further raise peak power to 93.4 MW (H7P5S5), indicating a coupled amplification effect. Dynamic stall is mainly triggered by pitch motion, expanding in scope and duration with motion amplitude; wave effects on stall remain limited. Platform motion also enhances wake recovery by increasing inflow shear and turbulence, leading to higher turbulent kinetic energy (TKE) and a reduced velocity deficit (ΔŪ). Waves compress the low-speed wake core and reduce ΔŪ from 0.248 (no-wave case) to 0.204 under H7 conditions at x/D = 3.0, with the effect being particularly evident under combined motion. Vortex visualization reveals that platform movement leads to vortex merging, ring thickening, and deflection, with combined motion creating the strongest mixing. Wave-generated vortices interact with tip vortices near the surface, becoming more intense under larger wave heights. In general, platform motion is the main factor in FOWT unsteady aerodynamics, while waves have secondary but cooperative effects by changing inflow structures and aiding wake recovery. This study offers theoretical support and engineering guidance for aerodynamic design optimization and wind farm layout of next-generation ultra-large floating offshore wind turbines.
Xie, BinSun, HaiyingChen, Ye
The floating offshore wind turbine (FOWT) system contains a wide range of interdisciplinary knowledge, including the aerodynamics of wind turbines, the hydrodynamics of floating platform, and mooring system, as well as the complex coupling interactions among these domains. Due to this inherent complexity, achieving accurate simulation and analysis has remained a significant challenge. To address this issue, the present study develops a coupled aerodynamic-hydrodynamic framework based on the open-source computational fluid dynamics (CFD) software OpenFOAM. The framework incorporates multiphase flow, dynamic morphing and overset mesh techniques to facilitate high-fidelity analysis of FOWT. The aerodynamic performance of the IEA 15 MW reference wind turbine and the hydrodynamic response of the UMaine VolturnUS-S semisubmersible platform are independently validated against OpenFAST or experiments to ensure the reliability of the proposed framework. The results show strong agreement, confirming that the simulations accurately capture realistic aerodynamic and hydrodynamic performance, which are then applied in coupled aero-hydrodynamic FOWT analysis. The effects of the wind turbine on floating platform hydrodynamic responses and the impact of the floating platform on wind turbine aerodynamics are investigated in the coupled simulation. The results show that the speed, thrust, and torque of the wind turbine fluctuate with the motion of the floating platform, which is closely linked to the surge and pitch motion. Furthermore, a comparison of the platform response in the coupled simulation with that considering only wave loading reveals minimal change in heave motion, but a significant increase in surge and pitch motion due to the wind turbine aerodynamic load. Therefore, the aerodynamic and hydrodynamic components of the FOWT are mutually dependent, underscoring the necessity of a comprehensive analysis to achieve accurate results.
Dong, XinhuiDeng, Xiaowei
In actual marine environments, the aerodynamic behavior and wake properties of floating offshore wind turbines (FOWTs) are largely shaped by the pitching movement of their supporting platforms. The present study examines the aerodynamic performance and wake characteristics of a complete wind turbine system, encompassing its blades, nacelle, and tower, through the application of computational fluid dynamics (CFD) and the overset mesh method. This paper conducts an in-depth examination of how the amplitude and period of pitching motion influence the aerodynamic loads and flow field associated with wind turbines. The power and wake velocity results calculated in the study are compared with those obtained from numerical simulations by other researchers. The results indicate that the mesh and simulation parameters employed in this research precisely capture the aerodynamic characteristics and flow field surrounding the turbine. This work deliberates on how the amplitude and period of pitch motion impact the turbine aerodynamic behavior, while also conducting a quantitative analysis of the influence on the wake velocity recovery and wake range of the turbine. Findings from this research reveal that both the amplitude and period of pitching motion exert a significant impact on power output, thrust force, and wake-related properties.
Chen, WeiChen, JianChen, YeSun, Haiying
As the trend toward larger wind turbines continues, the increasing length of blades imposes higher demands on their structural properties. And in actual engineering, wind turbine blade accidents occur frequently. Consequently, ultra-long flexible blades at the hundred-meter scale typically employ composite materials. However, due to the high cost of composites, it is necessary to minimize blade weight to control costs. This study utilizes the MATLAB simulation platform combined with pattern search algorithms to optimize the composite layup of large wind turbine blade structures. The structural properties of the optimized design are then compared and analyzed against those of the reference structure. Simultaneously investigate the impact of different loads on the optimization results. The results demonstrate that the pattern search algorithm can optimize blade layup thickness, spar chordwise position, and spar width, yielding a new blade structure with improved performance. During structural optimization, adjustments to the spar, leading edge, and shear web primarily focus on thickness reduction, while modifications to the trailing edge and spar width depend on the specific applied loads. Reducing the thickness of the web and leading edge along the blade span while increasing the thickness and width of the spar region, along with appropriate adjustments to trailing edge thickness based on loading conditions, achieves both mass optimization and enhanced structural reliability. These findings provide valuable guidance for the structural design optimization of ultra-long flexible blades in large wind turbines, and have positive significance for the safety and economy of wind farm operation, offering a more scientific, efficient, and practical approach to their design.
Cao, GuangchuanGuo, XiaMeng, Hang
As a part of new energy, wind power generation requires precise wind speed forecasting to enhance grid reliability. This paper proposes a hybrid time-series pattern prediction framework designed to continuously forecast wind speed across multiple wind turbine units. The proposed framework incorporates three key components. First of all, a multi-scale temporal pattern extraction module is introduced to improve the capability of the model to capture time-dependent structures, thereby enhancing predictive accuracy and robustness. Second, a three-dimensional adaptive probabilistic attention mechanism is developed to reinforce temporal feature interaction and fusion, ensuring both efficiency and performance. Third, a feature-factor pattern fusion strategy is applied to effectively model complex wind speed variations under diverse influencing factors, while reducing computational burden during training. Through comparative experiments, our model has better performance, obtaining an RMSE of 36.3, MAE of 5.34, and MAPE of 1.02%, which confirms its capability in delivering accurate and stable wind speed predictions.
Wang, HaiqiangXiao, HuanZhu, XiaoxunGao, Xiaoxia
With the introduction of China’s dual-carbon goals (carbon peak and carbon neutrality), renewable energy has experienced rapid development in the country, particularly wind energy, which has established a pivotal role within the new energy sector. However, the inherent fluctuations in wind power generation pose significant challenges to maintaining grid stability and operational reliability. In power systems where the proportion of installed wind power capacity has significantly increased, the allocation of flexible resources becomes crucial. These resources help the system adapt to fluctuations in wind power generation and load demand, avoid wind power curtailment, and reduce costs. In addition, energy storage enhances grid flexibility and stabilizes renewable energy, but is constrained by high costs. Therefore, optimizing energy storage allocation and improving its economic efficiency have become urgent issues. This study focuses on flexibility adequacy assessment and resource allocation, proposing an optimization model that incorporates constraints from wind power, thermal power, energy storage, and load shedding. The model aims to identify the optimal energy storage configuration strategy to minimize operational costs while ensuring system flexibility adequacy. The model is constructed and simulated using MATLAB, with complex optimization problems solved using the Gurobi solver. The research involves developing flexibility evaluation indicators, determining the optimal energy storage capacity configuration, and creating an economic objective function. The goal is to minimize costs while ensuring system flexibility.
Peng, JianWei, JinpengZhu, ZhengyinHu, JianminLi, YuxiangMiao, GangZhang, Huaide
With the rapid growth of renewable energy sources such as photovoltaics, energy storage systems, and wind power, hybrid AC/DC microgrids (H-MGs) are gradually emerging as a key technology for achieving efficient interconnection between generation units and load demands. However, issues such as communication delays, unequal power sharing, and the restoration of voltage and frequency in hybrid microgrids have posed serious threats to the stable operation of microgrids. We also need to appropriately adjust the simulation parameters to ensure that the proposed control framework maintains sufficient flexibility under different load conditions and achieves high operating efficiency in simulation. To tackle these challenges, this paper proposes a distributed secondary control strategy grounded in coordinated consensus and combined with droop-based interlinking converters (ICs) to realize power coupling between the AC and DC subgrids. The proposed method enables precise active-power sharing among AC and DC distributed generators, balanced reactive-power sharing between AC subgrid and ICs, and effective restoration of system frequency and voltage. By introducing consensus indices into the IC control scheme—relying only on key indicators from both sides—the power-coupling capability of ICs is enhanced while communication complexity is reduced. All control objectives, including frequency /voltage restoration and proportional power sharing, are achieved at the secondary-control level. Based on the simulation results, the effectiveness of the proposed method is validated in this paper. Compared with existing methods, the proposed strategy not only achieves accurate power sharing and stable frequency /voltage restoration, but also rapidly recovers system stability under load variations, thereby enhancing the overall stability, reliability, and operational flexibility of hybrid AC/DC microgrids.
Yu, PeijieZhang, FanghaiSun, WeiYuan, WeiboPeng, Bo
Autonomous Inspection via small Unmanned Aircraft Systems (sUAS) is increasingly utilized across industrial use cases such as inspection of bridges, buildings, construction sites, roadways, transmission lines, pipes, wind turbines and power systems (1). In principle, the system workflow of inspection; identification and characterization of defects; and mapping in space is very similar across industries. Boeing and Proxim (A Near Earth Autonomy Company) have partnered to pursue this technology in the Aerospace and Defense industry for General Visual Inspection (GVI) of airframes predominantly in a maintenance setting. This activity began by deploying Proxim’s Autonomous Aircraft Inspection (AAI) technology and Boeing's Automated Damage Detection Software (ADDS) on Boeing C-17 Globemaster III at Joint Base Pearl Harbor-Hickam. It has expanded to offer U.S. Department of War (DoW) and Commercial customers aircraft-agnostic enhanced exterior GVI capability at point of need by leveraging unique ADDS AI algorithm in support of both home station and deployed operations. This paper gives an overview to industry developments in Autonomous Inspection, and the development AAI/ADDS technologies.
Ransick, HayleyGatto, VinceRhodes, PeterCoccia, CharlesNevinsky, Michael
The aim of this study is to develop a methodology to significantly reduce emissions in bus fleet renewal scenarios by investigating both technical and economic aspects. This work presents a case study based on Elba Island, Italy, which investigates optimal solutions for replacing existing Diesel buses through a total cost of ownership analysis. The investigation is carried out for four different potential scenarios: renewing the fleet with Diesel buses, renewing the fleet with electric buses, adopting fuel cell buses, and implementing a hybrid solution. The latter represents a synergistic solution that integrates fuel cell buses with the development of a hydrogen refueling station driven by a proton exchange membrane electrolyzer, unlocking the techno-economic potential of self-producing green hydrogen for bus refueling. The novelty of this study is its integrated methodology that combines a total cost of ownership analysis with a tailored design of a green hydrogen production network optimized for continuous fleet operation. A constrained optimization algorithm was employed to determine the optimal configuration of key plant components, including the proton exchange membrane electrolyzer system size, the amount of photovoltaic panels and wind turbines, and the capacity of the hydrogen storage tank. The grid-based alternative offers a simple payback period under 4 years and a total cost of ownership of 6 M€, making it more cost-effective than the 6.5 M€ electric and 7.5 M€ Diesel options. These results provide a scalable, replicable roadmap for accelerating sustainable public transport adoption in similar contexts.
Bove, GiovanniSorrentino, MarcoBaldinelli, AriannaDesideri, Umberto
In view of the complex intertidal terrain challenges faced by offshore wind power maintenance, this paper optimizes the lightweight design of multi-terrain tracked vehicles. The structure was optimized by finite element analysis, and the maximum stress was 211.68 MPa ( lower than the safety limit of 230 MPa), and the maximum deformation was 5.25 mm, which ensured the stability and stiffness. Titanium alloy has the advantages of high strength, low density and corrosion resistance, which improves the durability of the frame while reducing the weight of the frame. Advanced manufacturing technologies such as phase transformation superplastic diffusion welding optimize the connection between TC4 titanium alloy and stainless steel. Modal analysis and optimization techniques refine the structural parameters and improve the complex load performance. The research promotes the lightweight of the frame and provides theoretical and technical support for the design of multi-terrain vehicles.
Xu, HanXu, ShilinMa, WenboZhu, Wei
The path toward carbon-neutral mobility represents one of the greatest cultural transformations in recent human history. Positioned between industrial heritage, emerging mobility technologies, and the energy supply sector are the users of 1.5 billion motor vehicles worldwide. Conflicting publications on raw material availability, energy efficiency, and the climate neutrality of propulsion systems have led to widespread uncertainty. This Illustrated Energy Primer provides a new foundation for orientation. It begins with a visual explanation of the basic concepts of energy and power, followed by illustrative comparisons of typical energy demands in vehicles and households. The focus then shifts to common types of energy generation systems. Using regional examples—from coal-fired power plants to wind farms, solar installations, and balcony solar panels—the guide provides clear and accessible performance benchmarks for energy production. Next, nine individual experience profiles highlight how people across different life stages manage their vehicles responsibly and resource-efficiently. These range from a 16-year-old driver of a light electric vehicle, to a 55-year-old electric sport utility vehicle (SUV) user, to a 91-year-old woman using an electric mobility aid limited to walking speed. A broad range of drive technologies is covered in the Energy Primer, including comparisons with alternatives such as electric microcars, pedal-assist electric bicycles (pedelecs), and walking. Each user narrative outlines annual personal financial savings as well as the potential reduction in CO₂ emissions. These individual results are also scaled up to reflect the commuter mobility patterns of the Federal Republic of Germany (BRD). In this way, the Energy Primer builds a bridge between technical experts and everyday users. It aims to strengthen awareness of the value of energy in mobility and to encourage deeper engagement with the sometimes complex calculations behind energy balances. This is the first time such a compact and illustrated educational resource on energy and mobility is made freely available.
Daberkow, Andreas
Electricity is a fundamental necessity for individuals worldwide, serving as a force driving technological progress hitherto unimaginable. Electricity generation uses diverse methodologies based on available natural resources in a given geographic region. Conventional methods like thermal power from coal and natural gas, water-based hydropower, solar power from the sun, wind power, and nuclear power are used extensively, the former two being the dominant sources. The generation of nearly 70% of the world's electricity is estimated to be from thermal power plants; however, these operations lead to widespread environmental destruction, greenhouse emissions, and the occurrence of acid rain. Conventional thermal power plants run on the Rankine cycle principle of a boiler, a turbine, a condenser, and a pump. A similar method may be used in the Organic Rankine Cycle (ORC) with the use of solar energy, where heat is transferred to the working fluid in the boiler using a heat pipe, a passive heat transfer device. A closed system makes use of Liquefied Petroleum Gas (LPG) as the working fluid in the Organic Rankine Cycle, while acetone serves as the working fluid when used inside the heat pipe. The boiler is constructed to function within the pressure range of 4-7 bar, while the turbine is constructed to function at temperature levels of 150-200°C when optimized for maximum thermal efficiency. In this current research, a refrigerant boiler has been designed incorporating thermal management strategies to optimize efficiency. The rate of heat transfer from the solar collectors was analyzed under various conditions, and it was found that the evacuated tube collectors had temperature efficiencies ranging from 40-60% at various irradiation levels. Technical parameters unique to the solar collectors are an average flux of 500 W/m2 and a collector efficiency of 65% at the peak of sunlight intensity. The system can also sustain a boiler temperature of 250°C to allow for maximum system working fluid vaporization and pressure generation. The performance of the system was also subjected to different weather conditions, with particular emphasis on temperature variation and the effect on system efficiency. This research offers an insight into the development of solar-powered ORC systems with emphasis on their capability to generate clean and renewable energy. The research can also be applied to enhance the heat management of refrigerant boilers to allow for efficient temperature control and increased overall system efficiency in solar electric energy conversion.
Deepan Kumar, SadhasivamKumar, VDhayaneethi, SivajiMahendran, MSaminathan, SathiskumarR, KarthickA, Vikasraj
In 2022, the U.S. transportation sector was the largest source of greenhouse gas emissions in the country, with the combination of passenger and commercial vehicles contributing 80% of these emissions. As adoption of passenger electric vehicles continues to climb, sights are being set on the electrification of heavy-duty commercial vehicle (HDCV) fleets. The sustainability of these shifts relies in part on the addition of significant renewable energy generation resources to both bolster the grid in the face of increased demand, and to prevent a shift in the source of greenhouse gas (GHG) emissions to the grid, as opposed to a true net reduction. Additionally, it is necessary to quantify the variations in economic viability across the country for these technologies as it pertains to their productive capabilities. Doing so will encourage investment and ensure that the transition to electrified HDCV fleets is commercially viable, as well as sustainable. In an effort to meet these goals, multiple computational frameworks are used to locate suitable land for renewable infrastructure development, and to quantify spatiotemporal variations in the potential energy generation and financial viability of development sites across the Unites States. First, the Oak Ridge Siting Analysis for power Generation Expansion tool (OR-SAGE) is used to assess the suitability of land for potential wind and solar energy development across the contiguous U.S. From there, resource data from the National Solar Radiation Database (NSRDB) and the Wind Integration National Dataset (WIND) are used in concert with the National Renewable Energy Laboratory (NREL) Renewable Energy Potential (ReV) model to calculate the variation in potential generation capacity for each resource. Additionally, the capital and operational expenditures are calculated for an example configuration of each renewable technology. These measures are then used to calculate the levelized cost of energy (LCOE) of potential sites. All of these results are then processed and analyzed to determine where in the U.S. solar and wind energy are most viable. This viability is based on available generation potential, consistency and stability of energy generation over time, and economic viability with respect to LCOE.
Miller, BrandonSun, RuixiaoSujan, Vivek
This work addresses an innovative method for improving energy harvesting in Bladeless wind turbines (BWT) by implementing profile modifications to the wind turbine for fixing it in Unmanned Surface Vehicles (USV). The streamlined flow undergoes a transformation and generates a vortex in the vicinity of the structure when the wind impacts the BWT. As the velocity increases, the wind strikes the structure with greater force, resulting in an imbalance that causes the structure to vibrate. To convert this vibrational energy of the wind turbine into electrical energy, the research investigates the use of a variety of profile modifications to capitalize on the aerodynamic effect generated by the structure. The entire cylindrical shape is altered to tapered shape, airfoil shapes with coordinates such as NACA 0012, 0015, 0018, 4412 and 4420. In addition to these shapes, hybrid models were also constructed by merging models made from two airfoil coordinates, including NACA 0018 & 4412, NACA 4412 & 4420 and NACA 4412 & 4412. Computational fluid dynamics simulations are employed to design and investigate aerodynamic forces, torque, pressure and induced velocity of the diverse design profiles using ANSYS Workbench software. The analysis is performed under specific boundary conditions to determine the most effective design for enhancing energy extraction. The USV employs this efficient method of operating BWT to generate additional power from renewable sources by utilizing the high-velocity air generated in the environment. The results of the analysis indicate that the Hybrid 4412-4420 airfoil structured design performs better and is more efficient than the other models.
Veeraperumal Senthil Nathan, Janani PriyadharshiniRajendran, MahendranArumugam, ManikandanRaji, Arul PrakashSakthivel, PradeshStanislaus Arputharaj, BeenaL, NatrayanGanesan, BalajiRaja, Vijayanandh
The integration of advanced horizontal axis turbines (HATs) into unmanned marine vehicles (UMVs) significantly enhances their operational efficiency by providing power sources. These vehicles, designed for diverse applications, require efficient power systems to operate autonomously over extended periods. The major disadvantages are limited battery life and energy storage capabilities that restrict the operational range and endurance of the UMVs. Utilizing HATs in UMVs provides a renewable energy source, reducing operational costs. This continuous power supply enhances mission capabilities and promotes energy independence, making them ideal for long-term missions. Thus, using Computational fluid dynamics (CFD) models, hydrodynamic and aerodynamic analyses were carried out. For the hydrodynamic scenario, a velocity of 10 m/s and for the aerodynamic case, 27.7778 m/s, were taken into consideration. It is concluded that the UMV with Stepped HAT modification can be effectively employed for energy extraction because it provides the maximum torque, which is 50.65% more in hydrodynamic analysis and 58.03% more in aerodynamic study than the base case. It was also found that the performance was enhanced by the HATs, thus concluding that the modified HAT blades provided better results.
Gunasekaran, Durga DeviKannan, HaridharanSourirajan, LaxanaVinayagam, GopinathGnanasekaran, Raj KumarKulandaiyappan, Naveen KumarStanislaus Arputharaj, BeenaL, NatrayanRaja, Vijayanandh
NASA engineers have developed a new approach to mitigating unwanted motion in floating structures. Ideally suited to applications including offshore wind energy platforms and barges, the innovation uses water ballast as a motion damping fluid. Various designs have been developed to suit a number of different configurations depending on the specific applications.
Adoption of Electric Vehicles (EVs) reduces air pollution by reducing harmful gas emissions. Such adoption, however, needs a reliable and convenient charging infrastructure, including smart EV charging. Renewable energy sources such as solar photovoltaic cells, battery and wind energy systems can address these infrastructural gaps which work in conjunction with main grid power supply thereby providing low-cost electricity. This paper introduces an energy management algorithm for integrated renewable and grid power sources available at charging stations across India that considers techno-economic and environmental factors. The current work proposes a supervisory controller model that manages the load power demand of the charging station. The controller effectively deploys low cost energy sources based on the status of all available power supplies and reduces the overall charging costs in real time. The energy management algorithm ensures adequate stand-alone energy generation and storage at charging station for charging electric cars, even when renewable energy generation is low for variable charging load.
Shukla, AnkitKushwah, Yogendra SinghSuman, Saurabh
Mitigating environmental impacts is ever more crucial as wind energy technology expands to help meet the Nation’s goal of achieving a carbon pollution-free power sector by 2035 and net zero emissions economy by no later than 2050.
Rolling bearings play a critical role in rotating machinery, with their fatigue life directly impacting equipment’s operational reliability. This underscores the significant engineering application value of “fault diagnosis” (FD) technology for rolling bearings in mechanical, automation, and aerospace domains. Literature reviews highlight that a substantial portion of failures in machinery such as jet turbine engines, wind turbines, gear reducers, and induction machines are attributable to bearing issues. Early fault detection and preventive maintenance are therefore imperative for ensuring the smooth operation of rotating machinery. This paper focuses on rolling bearings, delving deep into FD technology using machine learning principles. It analyses the structure and common failure modes of rolling bearings, discussing an FD method based on machine learning. Specifically, the SE-DRN (“squeeze-exclusion deep residual network”) approach is employed, leveraging “variational modal decomposition” (VMD) to decompose bearing vibration signals and reorganize the resulting “intrinsic mode function” (IMF) components into an IMF component signal matrix. This matrix is then processed by a depth residual network with a channel attention mechanism for feature extraction and recognition, forming the SE-DRN-based FD model for rolling bearings. The research attains a remarkable average diagnostic accuracy of 98% across five different bearing state types, underscoring its superior accuracy compared to existing literature, thus showcasing the effectiveness of the SE-DRN approach in rolling bearing FD technology.
Muin, Abdullah-AlKhan, ShahrukhMiah, Md Helal
Ice build-up on aircraft and wind turbines can impact the safety and efficiency of their systems.
Bhutan is a small nation in the eastern Himalayas, between two of the world's largest neighbors and fastest-growing economies; China, and India. The GDP of the country is $2.707 Billion as of 2022. Bhutan’s largest renewable source is hydropower, which has a known potential of 30,000 MW. However, it has only been able to harvest only 1,480 MW (5% of the potential). The current overall electrification rate is 99% overall with 98.4% in rural areas. It exports 75.5% of total electricity generated in the country to India. However, the reliable supply of electricity remains a big challenge. The government is also pushing the use of renewable energy sources like solar and wind to diversify the energy mix and enhance the power security of the country. The share of renewable energy is very minimal at present amounting to 723 kW Solar PV and 600 kW Wind power. Bioenergy in the form of fuel wood, energy crops & crop residues, and cattle dung has great potential in the country as the country’s total energy demand is projected to grow at an average annual rate of 6.5% which is expected to reach 1,550 kilo ton of oil equivalent (KTOE) by 2030 from 725 KTOE in 2017. However, the country continues to use unsustainable use of biomass due to the use of conventional inefficient cook stoves, a lack of local knowledge, and the inability to produce and use modern and efficient biomass systems. The present study attempts to evaluate the challenges and potential suitability of Biomass-based Resources for meeting existing and future energy requirements of the country as it can’t solely depend upon hydro-power due to many vital reasons. The use of biomass resources for energy also fulfills the country’s mandate of not increasing GHG emissions as the country has the rare distinction of being the only carbon-negative country in the world.
Wangchuk, SingyeKumar, Naveen
This article presents a technical study on the integration of hybrid renewable energy sources (RES) with vehicle-to-grid (V2G) technology, aiming to enhance energy efficiency, grid stability, and mitigating power imbalances. The growing adoption of RES and electric vehicles (EV) necessitates innovative solutions to mitigate intermittency and optimize resource utilization. The study’s primary objective is to design and analyze a hybrid distribution generation system encompassing solar photovoltaic (PV) and wind power stations, along with a conventional diesel generator, connected to the utility grid. A V2G system is strategically embedded within the microgrid to facilitate bidirectional power exchange between EV and the grid. Methodologically, MATLAB/Simulink® 2021a is employed to simulate the system’s performance over one day. This research addresses a critical research gap in comprehensively evaluating the synergy between hybrid RES and V2G technology within a microgrid context. The study contributes by demonstrating the potential of EVs as dynamic energy storage units, effectively mitigating the intermittency of renewable energy (RE) and supporting grid stability. This is achieved by injecting or absorbing energy to address frequency deviation events and improve power flow based on demand needs and generated power from the source. The results highlight the capability of the V2G system to optimize energy flow, regulate grid frequency, and alleviate power imbalances. Main findings underscore the significant role of V2G in enhancing grid resilience and flexibility, especially during RE fluctuations and unexpected events. Moreover, the study underscores the feasibility of achieving sustainable energy goals through the coordinated operation of hybrid RES and V2G systems.
Al-Shetwi, Ali Q.
NASA engineers have developed a new approach to mitigating unwanted motion in floating structures. Ideally suited to applications including offshore wind energy platforms and barges, the innovation uses water ballast as a motion damping fluid.
The growing demand for transportation fuels and the global emphasis on reducing greenhouse gas (GHG) emissions have led to increased interest in analyzing transport GHG emissions from the life-cycle perspective. Methanol, a potentially carbon-neutral fuel synthesized from CO2 and H2, has emerged as a promising candidate. This paper conducts a comprehensive life-cycle analysis (LCA) of the GHG emissions associated with the methanol production process, utilizing data inventory from China in 2019. To simulate the synthesis and distillation process of methanol, Aspen Plus is employed, using parameters obtained from actual plants. GHG emissions are then calculated using the GREET model, incorporating updated industry statistics and research findings. The CO2 necessary for methanol production is captured from factory flue gas. Two different sources of H2 are considered: one from Coke Oven Gas (COG) and the hydrogen-rich gas byproduct resulting from COG methanation (Case 1), and the other via water electrolysis (Case 2). The GHG emissions of methanol production for Case 1 and Case 2 are found to be -0.08 and 6.36 kg CO2-eq/kg methanol, respectively. However, if wind power is the sole source of electricity, the GHG emissions for both cases are reduced to -0.68 and -0.65 kg CO2-eq/kg methanol, respectively. The adoption of CO2 capture technology is the main reason for both systems to achieve negative emissions. The lower GHG emissions in Case 1 are attributed to the energy and emission allocation of byproducts. To achieve net zero GHG emissions in Case 2, the GHG emissions of electricity generation need to be reduced by 88% of the current level. This reduction is expected to be achieved by 2050, based on projected power generation mixes and efficiency improvements in water electrolysis in China.
Fu, YangWang, BuyuShuai, Shijin
In recent years, the number of electric vehicles (EVs) has grown rapidly, as well as public interest in them. However, the lack of sufficient range is one of the most common complaints about these vehicles, which is particularly problematic for people with long daily commutes. Thus, this article proposed a solution to this problem by installing micro wind turbines (MWTs) on EVs as a range extender. The turbines will generate electricity by converting the kinetic energy of the air flowing through the MWT into mechanical energy, which can have a reasonable effect on the vehicle aerodynamics. The article uses mathematical modelling and numerical analysis. Regarding the modelling, a detailed EV model in MATLAB/SIMULINK was developed to analyze the EV performance using various driving cycles in real time. In terms of numerical analysis, a detailed computational fluid dynamics (CFD) model has been implemented on a sample EV (Kia Soul) and an MWT using the Moving Reference Frame (MRF) method to act as a virtual wind tunnel in order to investigate the aerodynamic performance. The optimum location for the turbines to be installed has been identified on the front bumper of the car. The MWT has been designed from scratch using Qblade and Xfoil solvers by testing many foil sections and blade parameters to find the best design for the vehicle speed range. After using the designed turbine numerical results and implementing them into the EV model in MATLAB/SIMULINK, the results become more accurate. The vehicle efficiency increased by 13.1% at the Federal Test Procedure (FTP) highway driving cycle with five MWTs installed in the front bumper of the car, and its range increased by 24 km on a full charge; however, three MWTs have been studied in the CFD analysis to investigate the effect of the system on the vehicle drag coefficient, which is considered as the main trade-off of the proposed work. The analytical and numerical errors, points of strength, and weaknesses in each method and model have been determined to verify the entire work.
Ebaid, MunzerShahin, Zin Al Abdin A. E.Alshawabkeh, Mohammad M. D.
The second-life use of batteries from electric vehicles (EV) represents an excellent and cost-effective option for energy storage applications, including the control of fluctuations in energy supply and demand or in combination with solar photovoltaic and wind turbine. Indeed, these batteries are normally replaced from EV use before the end of their service life, when they still have 70-80% of the original capacity. Depending on the cell chemistry and the specific design, such batteries can still be employed in less stressful applications than the automotive one, including commercial, residential, and industrial applications. With the aim to promote the transition to a circular closed-loop economy for spent traction batteries, this study consists in a systematic literature review of available options for reusing EV batteries as a storage system in a factory environment, highlighting benefits and critical aspects.
De Luca, CristinaSilvestri, LucaForcina, AntonioSilvestri, CeciliaBella, Gino
In the context of the race toward minimum road transportation carbon dioxide (CO2) emissions, the needs for tools comparing various powertrain options are of the highest importance. Various authors have demonstrated the necessity to take into account the full life cycle assessment (LCA), a simplified tank-to-wheel calculation being unsatisfactory in providing guidance regarding the optimized technological choices depending of variables manufacturing and operating conditions. There are several examples to be found in the literature but they have been found to be very specific to most of their assumptions (e.g., vehicle models, electricity carbon intensity for usage or production, etc.). This paper focuses first on possibly to establish a more general model and relative graphic tool to compare carbon foot print of various powertrains with incremental electrification levels of light-duty vehicles (spark ignition engine, full hybrid, plug-in hybrid, and battery electric vehicle), enabling to choose relevant parameters for the production and the usage of the vehicles. As expected, the level of electrification is identified as a key parameter of the overall vehicle carbon footprint. However, electrifying the fleet represents a major challenge for the electricity generation system and grid, requesting detailed analysis. That’s the subject of the second part of the study, which also proposes a graphic way of analyzing the situation. Examples are being provided for European countries with different energy strategy (i.e., France and Germany), including a tentative to consider the possibilities offered by vehicle to grid (V2G) to overcome intermittency nature of ReNeWable energy sources (RNW) such as PhotoVoltaic solar (PV) and wind turbines (WIND).
Hébert, Guillaume
Wind turbines in cold climates are likely to suffer from icing events, deteriorating the aerodynamic performances of the blades and decreasing their power output. Continuous ice accretion causes an increase in the ice mass and, consequently, in the centrifugal force to which the ice shape is subjected. This can result in the shedding of chunks of ice, which can jeopardize the aeroelastic properties of the blade and, most importantly, the safety of the surrounding people and of the wind turbine structure itself. In this work, ice shedding analysis is performed on a quasi-3D, multi-step ice geometry accreted on the NREL 5MW reference wind turbine. A preliminary investigation is performed by including the presence of an ice protection system to decrease the adhesion surface of the ice on the blade. A reference test case with a simple geometry is used as verification for the correct implementation of the procedure. The procedure was shown to be robust and will be used in the future within an optimization framework of a de-icing system.
Rausa, AndreaCaccia, FrancescoGuardone, Alberto
This paper aims to design a system to generate energy from flowing wind due to the motion of a vehicle on the road or from the flow of wind in compact areas to utilize the wasteful energy into a useful one. It is envisaged via a design and the improvement in efficiency of a Savonius Vertical Axis Wind Turbine and coupled in an integrated system with a Triboelectric Nanogenerator (TENG) that can generate a good amount of electrical energy. Aerodynamic calculations are performed numerically using a CFD Software, and the efficiency of the TENG is evaluated analytically. The Turbine's coefficient of power is validated with the literature for an inlet velocity of 7 m/s with a Tip Speed Ratio (TSR) of 0.75 and found to reasonably agree with that of experimental results. The baseline design is modified with a new blade arc angle and rotor position angle based on the recommended parameter ranges suggested by previous researchers. Simulations have been performed for different TSR values ranging from 0.25 to 1.5 with an interval of 0.25 with two applicable free stream velocities of 5 m/s and 7 m/s. Finally, the newly designed vertical axis wind turbine’s performance results obtained through CFD are used as input for the analytical performance prediction of the TENG. The results show that this approach could be feasible and useful for small power source applications.
Dadhich, BhaveshBamnoliya, FenilRajasingh, EdisonSenthilkumar, Sundararaj
Solar power is abundant — when the Sun is shining. Wind power is steady — when the wind is blowing. And a power grid is extremely convenient — until there’s an outage. But creating a steady supply of electricity from intermittent power sources is a challenge. NASA was focused on this problem more than 45 years ago, when the agency designed a new type of liquid battery during the energy price shocks of the 1970s.
The ability to precisely control electrical voltages on a large scale has made possible many efficient, powerful innovations, from high-speed electric trains to wind turbines to electric drive motors for everything from heavy earthmoving equipment to personal electric vehicles (EVs). But the equipment that manages this process — including power inverters, thyristors and variable-speed drives — requires high-performance power electronics cooling. As temperatures rise,the efficiency, reliability, and life spans of these devices drop, and the power electronics inside HEVs and EVs are no exception. Advancements in power electronic thermal management technologies will enable next generation automotive to fulfill increasingly demanding mission objectives. DC-DC converter and inverter systems slated for higher performances, reliable and sustainable applications. Even with very high efficiencies, the components of these systems produce kilowatts of power loss in the form of heat. The current paper would- discuss about different colling systems and emphasize on the benefits of immersion cooling to improve the thermal management system of various electronics components.
Sahoo, Pranati
Variable renewable energy (VRE), such as photovoltaic solar and wind turbines, will require new approaches to buffering energy within the grid. This must include significant ancillary services and longer duration storage to buffer seasonal variations in supply and demand. Such services may be economically provided by leveraging the battery resources of electric vehicles (EVs) for frequency response and energy storage for durations of up to a few hours, together with baseload and dispatchable power for longer duration buffering. Impact of Electric Vehicle Charging on Grid Energy Buffering discusses the unsettled issues and requirements needed to realize the potential of EV batteries for demand response and grid services, such as improved battery management, control strategies, and enhanced cybersecurity. Hybrid and fuel cell EVs have significant potential to act as “peakers” for longer duration buffering, and this approach has the potential to provide all the long-term energy buffering required by a VRE-intensive grid. Click here to access the full SAE EDGETM Research Report portfolio.
Muelaner, Jody Emlyn
Dr. Brandon Ennis, Sandia National Laboratories’ offshore wind technical lead, had a radically new idea for offshore wind turbines: instead of a tall, unwieldy tower with blades at the top, he imagined a towerless turbine with blades pulled taut like a bow.
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with colleagues at the University of Cambridge, have developed a new method to dramatically extend the lifetime of organic aqueous flow batteries, improving the commercial viability of a technology that has the potential to safely and inexpensively store energy from renewable sources such as wind and solar.
This article presents an original methodology for the multi-objective optimization of Continuously Variable Transmission (CVT) for a wind turbine (WT). The objective functions of this optimization problem are to minimize the weight and maximize efficiency. This methodology also considers the variations of parameters caused by different factors (manufacturing tolerance, uncertainties in the operating conditions). Using a probabilistic model, the proposed algorithm combines a propagation of uncertainties and an optimization of the function objectives. The optimization is performed using the Non-dominated Sorting Genetic Algorithm (NSGA-II) with the advantage of exploring the global design space and finding the best compromise between the objectives. In order to verify the solution obtained by this approach, results were compared to the ones obtained by a previous study.
Ziat, AbderazzakZaghar, HamidAit Taleb, AbdelmajidSallaou, Mohammed
Gear profile deviation is the difference in gear tooth profile from the ideal involute geometry. There are many causes that result in the deviation. Deflection under load, manufacturing, and thermal effects are some of the well-known causes that have been reported to cause deviation of the gear tooth profile. The profile deviation caused by gear tooth profile deformation due to interference-fit assembly has not been discussed previously. Engine timing gear trains, transmission gearboxes, and wind turbine gearboxes are known to use interference-fit to attach the gear to the rotating shaft. This paper discusses the interference-fit joint design and the mechanism of tooth profile deformation due to the interference-fit assembly in gear trains. A new analytical method to calculate the profile slope deviation change due to interference-assembly of parallel axis spur gears is presented. The effectiveness of the proposed computational algorithm to predict the deformation is demonstrated by comparing with measurements. A range of gears varying in size and interference-fit amount are analyzed by using the proposed algorithm to understand the deformation and the effect of the spur gear design variables on it. Finally, the effects of the interference-fit profile deformation and steps to mitigate the effects are discussed, along with gear train testing results and gear measurements of the gear designs that use the proposed methods.
Joshi, YashodhanChowdhury, Sanjib
Given their high-power density, large range of speed change, and reputation of being quieter than counter-shaft gear sets, planetary gear sets (PGS) have advantages to be applied in electric vehicle (EV) applications. Since electric drive unit (EDU) designs are often subject to accelerated development timelines with more versatile gear set layouts than conventional automotive transmissions, accurate prediction of PGS load sharing is needed. In the past, PGS load sharing imbalance used to be considered as a gear set problem focusing only on the effect to gear performance. Finding a closed-form formula has been a focus in gear design. However, early bearing failure in wind turbine gearboxes exposed the limitation of this strategy. With extensive field and laboratory testing, engineers started to notice that load sharing imbalance is essentially a system issue. Non-torque loads on PGS should be considered in the estimation by a gearbox system model. In this study, a virtual design, development, and validation (VDDV) method is proposed to calculate PGS load sharing accurately by using a validated deformable finite element contact analysis tool. The study concentrates on the effect and interaction of the non-torque load and planet carrier compliance that hasn’t been investigated before. To understand the PGS load sharing problem thoroughly, we define bearing load sharing for the first time, in conjunction with conventional planet gear load sharing. The study also represents PGS load sharing as a periodic variable instead of a constant factor, which supplies a mathematical tool for data interpretation. Through a parametric study of four EDU models, some design tips are clarified, such as increasing load or reducing carrier stiffness to improve load sharing. The work here confirms the complexity of load sharing problem which needs a system level numerical analysis. The proposed VDDV method can help hardware reduction in future EDU development. It also provides a validation foundation for more efficient analysis tools.
Ma, QinglongBlack, Derrick
, a Dutch-based startup and a spinoff from the University of Groningen, developed an inventive way to store offshore renewable energy where it is produced: offshore.
Aviation industry currently accounts for almost 3% of worldwide greenhouse gas (GHG) emissions. Despite the continuous efforts to reduce this environmental footprint, with the use of technological efficiency driven solutions and operational changes to reduce climatic effects, such as engine improvements, fleet renewals and navigation operational improvements, the industry, which is permanently challenged by the continuously stringent standards, is aware of the need of additional measures to tackle, and even reduce, the GHG emissions, by decoupling the world's industry average growth (almost 4.1% annually) to the aviation's carbon emissions. Given its inherent operational features, the aviation sector requires fuels with high specific energy and energy density. This technical requirement makes the well known clean and efficient electrical propulsion technology to be limited to niche aviation segments (short range and low capacity airplanes) in the short and medium terms. In this scenario, the so called Sustainable Aviation Fuels(SAF) - non fossil hydrocarbons, manufactured with renewable & sustainable feedstocks - appear as the big bet for the carbon footprint reduction for the medium and long range aviation. The biofuel SAF pathway, i.e. that which relies on biological feedstocks (crops and waste), already certified and produced to be used in blends with fossil jet fuel, into a drop-in fuel concept, has some environmental limitations associated with GHG net emissions, cost, and natural resources (land use and water) requirements. These limitations might set sustainable challenges to a massive future biofuel based SAF approach. In this context, the so called Power to Liquids (PtL) fuels, which comprises the production of synthetic liquid hydrocarbon fuels, using renewable electricity (for hydrogen generation with water electrolysis) and non fossil carbon dioxide (CO2) as the main feedstocks, is seen as a promising SAF pathway. Compared to biofuels, PtL SAF reaches higher area-related yields, with the intensive use of renewable electricity, such as photovoltaic and wind energy. The PtL's SAF water requirement is also significantly lower, compared to the biofuel production. Hence, the PtL SAF technology is seen as an important SAF pathway to enable a non fossil and fully sustainable fuel supply for aviation in the long run, avoiding the risks and adverse effects potentially associated with biomass based pathways. This work presents, based on an assessment of the researched technical literature, an overview of the PtL SAF technology, with a focus on the production methods and the required inputs, followed by an assessment of operational effects and costs for the aviation sector. The analysis shows that the PtL SAF appears as a promising sustainable SAF pathway, with a lower GHG footprint (into a Lyfecycle basis) and reduced water requirement, as well as a higher yield, compared to the plant-based SAF pathways (biofuels). Moreover, PtL SAF does not raise the demand for arable land, avoiding the so called food & fuel conflict. From a technical perspective, the PtL SAF might produce fuels suitable for even a net fossil fuel substitution (no blends). Nevertheless, the PtL SAF costs, which relies strongly on the renewable electricity price, are still a challenge to enable the competition with fossil jet fuel. This might initially require regulatory actions as well as further technological improvements, mainly associated with renewable electricity - fuel conversion and CO2 supply alternatives.
Barbosa, Fábio Coelho
This study proposes a self-powered and aerodynamically robust design of an EV. The vehicle design is proposed using the principles of bio mimicry following the standard procedures of transportation design. Speedform (a primitive form of the vehicle design generally considered as the visual vocabulary for transportation design) was developed computationally using AutoCAD. To enhance the Aerodynamic robustness of the vehicle, unique Aerodynamic Spoilers were proposed. VAWT (Vertical Axis Wind Turbine) incorporated with the Aerodynamic spoilers helps in generating the required power for the vehicle. The final external design of the vehicle was modelled on AutoDesk MAYA. The enhanced down force and reduced air drag were analyzed using Computational Fluid Dynamics (CFD). The realizable k-e turbulence model was used for the CFD analysis on ANSYS Fluent. Drag coefficient, lift coefficient and velocity contours were considered for optimizing and validating the geometry.
Moon, Rohini RamraoPrajapati, ShivamMISHRA, PRAYAG RAJ
Using Fourier Analysis and Theoretical Equation to Predict Bearing Raceway Waviness2021-01-10368/31/2021
Large size bearing’s raceway waviness is a most common NVH issue that presenting in manufactured bearing. Unlike small or medium size bearing with its raceway been honed after grinding. Typically, for large size bearing’s raceway are not honed due to its size limitation, unless there are special requirements from customers. Hence, it will inevitably generate great number of waves on the raceway circumference, which lead to a significant source excitation to the system. Although great amount of experiments substantiated that bearing waviness will not affect bearing life. However, annoyance noise is the main reason that customer reject bearings for quality concern. Hence, at the early stage of identifying raceway waviness issue at customer site could prevent from economic loss. Generally, the energy level caused by large size bearing waviness could be distinctive. Testing engineer will capture time domain vibration data by using radial accelerometer cells mounted on the housing for bearing health assessment. Then the vibration frequency spectrum can be converted by using Fast Fourier Transformation method. But, the preliminary step of using FFT is that people should know exact wave numbers on raceway circumference in order to trace back waviness excitation frequency. In this paper, a theoretical equation is developed, combining with common Fourier Analysis method. pinpoint raceway wave numbers in a fast and direct way become reality. A case example of CRB been used in a 5.5MW wind turbine generator and its NVH data will be analyzed for waviness equation prediction. Finally, the problematic bearing is also checked by waviness analyzer to confirm exact wave numbers on raceway circumference.
Chen, George (Huangxing)Dalen, Piet VanNijen, Gerrit VanWu, Zhengjiang
For years, spring set/electrically released brakes have provided failsafe braking and holding in a multitude of applications. Generally mounted on a motor or drive shaft, the brakes offer holding and dynamic stopping in applications ranging from large wind turbines to small servo motors. Specially designed brake controls are a critical factor of brake performance in any application.
Combustion engines using alternative and/or renewable fuels are vital to reduce emission of greenhouse gases. The property of such fuels may vary significantly. The heat release rate of bio and natural gas varies of natural reasons, which is known to cause problems when used in internal combustion engines. Hydrogen is an attractive renewable fuel that has a high potential to reduce greenhouse gas emission. Bio and natural gas can be mixed with hydrogen and the content may vary depending on the availability, e.g., depending on the production from solar and wind power. Variations in the fuel property reduces the engine efficiency, unless the combustion phase is estimated and the ignition (combustion) timing is adapted to compensate for the varying fuel property. Hereby the drivability can be improved, and the fuel consumption decreased significantly, reducing the total cost of ownership and emission of greenhouse gases. However, there is not yet any widespread industrially available technique to estimate the combustion phase. In-cylinder pressure measurement is not a practical solution due to cost and life-time issues. Here, a strategy for ion current measurement signal processing is proposed as a viable alternative to in cylinder pressure sensors by estimating the peak pressure location (PPL) from the ion current. The PPL estimate meets the robustness requirements of industrial applications. The approach is described and evaluated on engine measurements. The results show that ion sense can be used for PPL estimation and the standard deviation from one estimate to another is in the order of 1-2 CAD, which can be further reduced by averaging. The PPL estimates can be used in a closed control loop to compensate the ignition timing when the fuel property varies - saving cost and reducing greenhouse gas emission.
Aengeby, Jakob
Closed Loop Control of the Combustion Phase in SI Engines Using Alternative Fuels126629/14/2020
Combustion engines using alternative and/or renewable fuels are vital to reduce emission of greenhouse gases. The property of such fuels may vary significantly. The heat release rate of bio and natural gas varies of natural reasons, which is known to cause problems when used in internal combustion engines. Hydrogen is an attractive renewable fuel that has a high potential to reduce greenhouse gas emission. Bio and natural gas can be mixed with hydrogen and the content may vary depending on the availability, e.g., depending on the production from solar and wind power. Variations in the fuel property reduces the engine efficiency, unless the combustion phase is estimated and the ignition (combustion) timing is adapted to compensate for the varying fuel property. Hereby the drivability can be improved, and the fuel consumption decreased significantly, reducing the total cost of ownership and emission of greenhouse gases. However, there is not yet any widespread industrially available technique to estimate the combustion phase. In-cylinder pressure measurement is not a practical solution due to cost and life-time issues. Here, a strategy for ion current measurement signal processing is proposed as a viable alternative to in cylinder pressure sensors by estimating the peak pressure location (PPL) from the ion current. The PPL estimate meets the robustness requirements of industrial applications. The approach is described and evaluated on engine measurements. The results show that ion sense can be used for PPL estimation and the standard deviation from one estimate to another is in the order of 1-2 CAD, which can be further reduced by averaging. The PPL estimates can be used in a closed control loop to compensate the ignition timing when the fuel property varies - saving cost and reducing greenhouse gas emission.
Aengeby, Jakob
The aim of this article is to study the possibility of integrating and designing an optimal continuously variable power-split transmission (CVPST) in the drivetrain of a wind system (rotor, gearbox, and generator). The work focused on the research and defining solutions in the preliminary design phase through structural and behavioral analysis of continuously variable power-split transmissions integrated into the driveline of this system. A CVPST is a gearbox whose gear ratio is dynamic; it can be controlled to take any value within its upper and lower limits. Therefore, regulating the rotation frequency of the shaft of the generator via the continuously variable transmission replaces the traditional solution by using the power electronics that connect the generator to the electrical grid. These systems would permit the turbine to operate at its maximum efficiency and the generator to produce power with a regular frequency without using other devices. Previous studies have suggested that continuously variable transmission achieves this purpose using classical or intelligent controllers, such fuzzy logic (FL), artificial neural network (ANN) or a hybrid technique, called adaptive neuro-fuzzy inference system (ANFIS).
Aittaleb, AbdelmajidSallaou, MohamedZaghar, H.
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