bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical model and dynamic simulink simulation of PEM electrolyzer system
Authors: Fei Danxiong , Fan Wenwen , Dou Zhenlan , Zhang Chunyan
Published: November 2023

Hydrogen, being the most abundant element in the universe, holds great promise as an energy carrier for decarbonizing various economic sectors. In particular, green hydrogen production through water electrolysis is essential for achieving this goal, with polymer electrolyte membrane (PEM) water electrolyzers playing a crucial role. PEM water electrolyzers are known for their rapid response, enabling them to effectively adapt to fluctuations in renewable energy sources. Nevertheless, rapid load changes can result in the rapid build-up of heat within the electrolytic cell, leading to a sharp increase in temperature and potentially harming the cell. To address this challenge, we developed an electrolysis water system model using MATLAB and validated its accuracy through experiments. This model allowed us to explore the factors influencing stack temperature and propose a fast and secure dynamic process control strategy. By laying the groundwork for subsequent control studies on PEMEC (Proton Exchange Membrane Electrolysis Cell) stacks and systems, this research facilitates further progress in their control and regulation.
Research on Carbon Emissions and Carbon Reduction Paths of Power Generation Enterprises under the Dual Carbon Target
Authors: Yang Peng , Yao Minfang , Chen Chunyi , Zhu Huangru , Tao Yanfeng
Published: November 2023

Achieving the dual carbon goal is a profound and challenging social transformation. The difficulty is mainly reflected in the fact that economic growth is usually linked to energy consumption. In today's society, no country or industry can completely abandon traditional energy, and the use of traditional energy, namely fossil fuels, would bring carbon emissions. Therefore, reducing carbon emissions while ensuring economic growth and achieving the dual carbon goals is an important issue at present. This article conducted a series of carbon emission analysis and carbon reduction path research for power generation enterprises, which are the major emitters of carbon emissions, based on the background of dual carbon goals.
The development of nuclear power and related environmental evaluation due to nuclear accidents
Authors: Zhao Xuanbo
Published: November 2023

Nuclear power has played a pivotal role in meeting the growing global energy demand. However, the development of nuclear energy has been punctuated by a series of high-profile accidents, such as Chernobyl and Fukushima, which have raised significant concerns regarding its environmental impact. This paper aims to evaluate nuclear energy through data by using additional methods and to provide an overview of historical development of nuclear power technology and nuclear accidents. In order to evaluate thoroughly, the method of ratio estimation had been applied to find the trend for nuclear energy in previous decades and the potential development in the future. As a result, it emphasizes the effectiveness of nuclear energy changes structure of energy outputs in some countries. France, for instance, has already placed nuclear power as the main source for clear energy output. The paper proofs the development of nuclear power has been marked by significant improvements in safety and environmental consciousness. However, the specter of nuclear accidents looms large, necessitating ongoing vigilance and robust environmental evaluation processes. Despite that, the paper still contains additional assumption needed to be solved or explained.
Energy-Saving Bias in Green Technology Innovation A Spatial and Temporal Analysis of manufacturing in China
Authors: Liu Yang , Li Feng , Dai Jingjing , Li Tixin
Published: November 2023

This study presents an in-depth analysis of the energy-saving bias in green technology innovation across 30 provinces in manufacturing from 2011 to 2021, utilizing a novel Malmquist-Luenberger multidimensional decomposition index based on the directional distance function. The research reveals that green innovation, characterized predominantly by energy conservation, plays a pivotal role in driving China's green total factor productivity. The impetus for innovation in energy saving is found to surpass that of emission reduction in manufacturing enterprises. Energy-saving biased green technology innovation, originating in economically advanced provinces, has gradually expanded to the northern region, and it encompassed the majority of provinces in China. This type of innovation serves as the primary driver of regional green innovation. The study also identifies a conspicuous spatial aggregation effect of energy-saving biased green technology innovation, linked intrinsically to the degree of industrial aggregation and the spatial correlation effect of innovation.
Arduino-based Automatic Light Switching System
Authors: Li Moqi , Zhang Ziqian , Yin Haocheng , Liu Chang-huan , Jiang Feng-min
Published: November 2023

This article focuses on the problem of high power consumption caused by long working hours of lights, and designs an automatic light switch system based on the number of people to achieve energy-saving effects. After experiencing the process of selecting hardware, designing circuits, writing programs, structural design, 3D modeling, 3D printing processing, assembly, etc., an automatic light on/off system has been designed, which is low-cost and can achieve automatic light on/off based on Arduino microcontroller technology, playing a role in saving electricity to a certain extent.
Achieving energy transition through spatial planning - A case of onshore wind energy planning procedures optimization in China
Authors: Guan Jinjin , Xiong Jun
Published: November 2023

Wind energy is expected to be an effective solution to mitigate climate change and environmental pollution with broad resource distribution, decarbonization characteristics, and mature technologies. However, the rapid expansion of wind energy may also bring about new issues in space allocation and land use conflicts. Integration research of wind energy into spatial planning framework is imperative. Based on the dynamic change theories and conventional energy planning process, this paper proposed a planning framework with four main phases: 1) preparation, analysis, and orientation; 2) model design; 3) optimization and systematization; 4) implementation and supervision. Under the new framework, the connotation of wind energy planning and existing issues have been re-examined, and the planning procedures have been reorganized to correspond to the Chinese spatial planning system and energy development targets. Principles, priority, and systematization measures were discussed to optimize the planning system from the organizational perspective. The newly constructed framework connected the wind energy development plan and spatial planning into well-organized procedures with definite principles, targets, implementation guidelines, and supervision mechanisms at each planning level. The outcome of the research can be utilized as a guideline strategically positioning of planning goals and content.
Numerical simulation study on the heat dissipation characteristics of an air-cooled radiator
Authors: Yan Kai , Li Feng , Ren Jing
Published: November 2023

This article conducts numerical simulation calculations on the heat dissipation characteristics of an air-cooled radiator. The results show that under natural heat dissipation conditions, the maximum temperature of air-cooled radiators with flat heat dissipation covers decreases by 9.6% compared to radiators without heat dissipation covers, and the maximum temperature of air-cooled radiators with array raised heat dissipation covers decreases by 9.9%; Under forced air cooling conditions, the maximum temperature of an air-cooled radiator with a flat heat dissipation cover decreases by 12.7%, while the maximum temperature of an air-cooled radiator with an array raised heat dissipation cover decreases by 13.3%.
Research on the implementation path of event carbon neutrality
Authors: Hou Peng , Wang Qiang , Wang Jie , Yang Kun , Du Xiyue , Huang Siyu
Published: November 2023

This essay explores the concept of activity-based carbon neutrality as a critical component in achieving carbon emission reduction targets. With the Chinese government’s commitment to carbon sequestration by 2030 and carbon neutrality by 2060. activity-based carbon neutrality has gamed prominence as a hot topic in environmental discussions. The essay emphasizes the significance of activity-based carbon neutrality in promoting public awareness and participation in carbon reduction efforts. It highlights the existing research gap in this field and stresses the need for exploring methodologies to achieve activity-based carbon neutrality. The essay outlines the accounting standards for activity-based carbon neutrality, focusing on large-scale events and offering practical examples of carbon emission reduction measures during the preparation, execution, and conclusion phases of activities. Additionally, it introduces carbon offsetting methods such as carbon quotas and carbon credits. The article also presents a specific case study of the “Six-Five Environment Day National Event” held in Liaoning Province, which successfully achieved carbon neutrality through various initiatives. Overall, the essay encourages further investigation into activity-based carbon neutrality to enhance overall carbon reduction efforts.
Exploration and practice of zero-carbon intra-park in the context of Carbon peaking and Carbon neutrality Goals： A case study on an intra-park
Authors: Zhang Jun , Qin Yipeng , Feng Chao , Qiao Biao , Song Jialiang , Liang Shukui , Mu Lichun , Wang Lu
Published: November 2023

Aiming at the planning of zero carbon park under the background of double carbon, tins paper takes an industrial park as an example, and analyzes and evaluates the industrial planning situation, energy resources situation and energy plaiming situation of the park based on the concept of “passive priority, active optimization”. Taking the project as the blueprint, integrating the building energy-saving measures and the advanced nature and carbon reduction ability of the integrated smart energy technology, starting from the overall optimization layout of the park, covering the industrial structure, buildings, transportation, energy and other key areas of the park, the comprehensive application of low-carbon technology forms such as building micro-environment, ultra-low energy consumption building system, efficient integrated energy system and renewable energy. Total carbon emissions as the core goal, to achieve the goal zero carbon zone. This study for the project and project time zero carbon building and future zero carbon park planning to provide the reference of the same kind of park.
Effect of Green Finance on Industrial Carbon Emissions in China——Empirical Analysis Based on Provincial Panel Data
Authors: Zhou Yingying , Zhou Zhuoran , Zhang Youxin , Chang Yilin
Published: November 2023

Based on the Environmental Kuznets Curve (EKC), this paper empirically analyzes the impact of green finance development on industrial carbon emissions in China by using the panel data of Chinese mainland province. It is found that the development of green finance has significantly suppressed the industrial carbon emissions in China. Heterogeneity test shows that the inhibition effect on carbon emission in central China is the most obvious, and the inhibition effect on carbon emission in eastern and western regions decreases in turn. Technological progress significantly inhibits carbon emissions, especially in central China, followed by the western region and finally the eastern region. It is suggested to improve the green and low-carbon financing system, support the optimization of energy consumption structure and guide substantive technological progress, so as to promote the realization of carbon emission reduction targets.
Simulation des écoulements gravitaires avec les modèles d’écoulement en couche mince : état de l’art et exemple d’application aux coulées de débris de la Rivière du Prêcheur (Martinique, Petites Antilles)
Authors: Peruzzetto Marc , Grandjean Gilles , Mangeney Anne , Levy Clara , Thiery Yannick , Vittecoq Benoit , Bouchut François , Fontaine Fabrice R. , Komorowski Jean-Christophe
Published: November 2023

La quantification de la propagation des glissements de terrain est une étape clé de l’analyse des risques gravitaires. Dans ce contexte, les modèles d’écoulement en couche mince sont de plus en plus utilisés pour simuler la dynamique d’écoulements gravitaires comme les coulées de débris. Ils sont plus souples d’utilisation et moins coûteux en temps de calcul que des modèles 3D plus complexes, et fournissent des informations plus précises sur les vitesses et les épaisseurs des écoulements que des méthodes purement empiriques. Dans cette revue de la littérature, nous présentons les principales rhéologies utilisées pour modéliser des écoulements gravitaires homogènes, et donnons un exemple d’application pratique avec la Rivière du Prêcheur (Martinique, Petites Antilles). Nous discutons ensuite les principales pistes de développements permettant d’utiliser ces modèles dans le cadre d’études opérationnelles d’analyse d’aléas et de risques.
A decade after the creation of the oral surgery specialized graduate degree in France: assessments and prospects
Authors: Le Maître Jeanne , Alpy Alexandre
Published: November 2023

Introduction: The Oral Surgery Specialized Graduate Degree (Diplôme d’Études Spécialisées en Chirurgie Orale, DESCO) was created in France in 2011. The purpose of this study was to assess the current situation, ten years after its creation. The evaluation concerns both the training and the professional opportunities. Material and Method: An observational, cross-sectional, descriptive study was performed in 2022 on students who were enrolled in the DESCO-residencies and on former students from this residency. Eleven generations of students (from 2011 to 2021) were included in our study, which represents 330 persons. Each enrolled subjects had to fill an anonymous survey. Conclusions: The current situation’s review obtained in this study is consistent with the initial purpose of this new degree’s creation: training practitioners, specialized in oral medicine and surgery, to provide a quality healthcare in this sector in deficit.
Radiotracers in the Diagnosis of Pain: A Mini Review
Authors: Hascalovici Jacob , Babb Anthony , Norwood Braxton A.
Published: November 2023

The diagnosis and understanding of pain is challenging in clinical practice. Assessing pain relies heavily on self-reporting by patients, rendering it inherently subjective. Traditional clinical imaging methods such as computed tomography and magnetic resonance imaging can only detect anatomical abnormalities, offering limited sensitivity and specificity in identifying pain-causing conditions. Radiotracers play a vital role in molecular imaging that aims to identify abnormal biological processes at the cellular level, even in apparently normal anatomical structures. Therefore, molecular imaging is an important area of research as a prospective diagnostic modality for pain-causing pathophysiology. We present a mini review of the current knowledge base regarding radiotracers for identification of pain in vivo. We also describe radiocaine, a novel positron emission tomography imaging agent for sodium channels that has shown great potential for identifying/labeling pain-producing nerves and producing an objectively measurable pain intensity signal.
Gate tunable terahertz cyclotron emission from two-dimensional Dirac fermions
Authors: Benhamou-Bui B. , Consejo C. , Krishtopenko S. S. , Szola M. , Maussang K. , Ruffenach S. , Chauveau E. , Benlemqwanssa S. , Bray C. , Baudry X. , Ballet P. , Morozov S. V. , Gavrilenko V. I. , Mikhailov N. N. , Dvoretskii S. A. , Jouault B. , Torres J. , Teppe F.
Published: November 2023

Two-dimensional Dirac fermions in HgTe quantum wells close to the topological phase transition can generate significant cyclotron emission that is magnetic field tunable in the terahertz frequency range. Due to their relativistic-like dynamics, their cyclotron mass is strongly dependent on their electron concentration in the quantum well, providing a second tunability lever and paving the way for a gate-tunable, permanent-magnet Landau laser. In this work, we demonstrate the proof-of-concept of such a back-gate tunable THz cyclotron emitter at a fixed magnetic field. The emission frequency detected at 1.5 T is centered at 2.2 THz and can already be electrically tuned over 250 GHz. With an optimized gate and a realistic permanent magnet of 1.0 T, we estimate that the cyclotron emission could be continuously and rapidly tunable by the gate bias between 1 and 3 THz, that is to say on the less covered part of the THz gap.
Evolution of organic phosphor through precision regulation of nonradiative decay
Authors: Ju Cheng-Wei , Wang Xi-Chao , Li Bo , Ma Qiushi , Shi Yuhao , Zhang Jinyu , Xu Yuzhi , Peng Qian , Zhao Dongbing
Published: November 2023

Development of single-component organic phosphor attracts increasing interest due to its wide applications in optoelectronic technologies. Theoretically, activating efficient intersystem crossing (ISC) via
1
(π, π*) to
3
(π, π*) transitions, rather than
1
(n, π*) →
3
(π, π*) transitions, is an alternative access to purely organic phosphors but remains challenging. Herein, we designed and successfully synthesized the sila-8-membered ring fused biaryl benzoskeleton by transition metal catalysis, which served as a new organic phosphor with efficient
1
(π, π*) to
3
(π, π*) ISC. We first found that such a compound exhibits a record-long phosphorescence lifetime of 6.5 s at low temperature for single-component organic systems. Then, we developed two strategies to tune their decay channels to evolve such nonemissive molecules into bright phosphors with elongated lifetimes at room temperature: 1) Physic-based design, where quantitative analyses of electron–phonon coupling led us to reveal and hinder the major nonradiative channels, thus lighted up room temperature phosphorescence (RTP) with a lifetime of 480 ms at 298 K; 2) chemical geometry-driven molecular engineering, where a geometry-based descriptor ΔΘ
T1–S0
/Θ
S0
was developed for rational screening RTP candidates and further improved the RTP lifetime to 794 ms. This study clearly shows the power of interdiscipline among synthetic methodology, physics-based rational design, and computational modeling, which represents a paradigm for the development of an organic emitter.
Estimating the spatial amplification of damage caused by degradation in the Amazon
Authors: Araujo Rafael , Assunção Juliano , Hirota Marina , Scheinkman José A.
Published: November 2023

The Amazon rainforests have been undergoing unprecedented levels of human-induced disturbances. In addition to local impacts, such changes are likely to cascade following the eastern–western atmospheric flow generated by trade winds. We propose a model of spatial and temporal interactions created by this flow to estimate the spread of effects from local disturbances to downwind locations along atmospheric trajectories. The spatial component captures cascading effects propagated by neighboring regions, while the temporal component captures the persistence of local disturbances. Importantly, all these network effects can be described by a single matrix, acting as a spatial multiplier that amplifies local forest disturbances. This matrix holds practical implications for policymakers as they can use it to easily map where the damage of an initial forest disturbance is amplified and propagated to. We identify regions that are likely to cause the largest impact throughout the basin and those that are the most vulnerable to shocks caused by remote deforestation. On average, the presence of cascading effects mediated by winds in the Amazon doubles the impact of an initial damage. However, there is heterogeneity in this impact. While damage in some regions does not propagate, in others, amplification can reach 250%. Since we only account for spillovers mediated by winds, our multiplier of 2 should be seen as a lower bound.
Geodesics motion of test particles around Schwarzschild-Klinkhamer wormhole with topological defects and gravitational lensing
Authors: Ahmed Faizuddin
Published: November 2023

This study investigates the geodesic motion of test particles, both massless and massive, within a Schwarzschild-Klinkhamer (SK) wormhole space-time. We specifically consider the influence of cosmic strings on the system and analyze the effective potential, and observing that the presence of a cosmic string parameter alters it for null and time-like geodesics. Moreover, we calculate the deflection angle for null geodesics, and demonstrate that the cosmic string modifies this angle and induces a shift in the results. Additionally, we extend our investigation in this SK-wormhole space-time but with a global monopole. We explore the geodesic motion of test particles in this scenario and find that the effective potential is affected by the global monopole. Similarly, we determine the deflection angle for null geodesics and show that the global monopole parameter introduces modifications to this angle. Lastly, we present several known solutions for space-times involving cosmic strings and global monopoles within the framework of this SK-wormhole.
A clarification on prevailing misconceptions in unimodular gravity
Authors: Bengochea Gabriel R. , León Gabriel , Perez Alejandro , Sudarsky Daniel
Published: November 2023

The traditional presentation of Unimodular Gravity (UG) consists on indicating that it is an alternative theory of gravity that restricts the generic diffeomorphism invariance of General Relativity. In particular, as often encountered in the literature, unlike General Relativity, Unimodular Gravity is invariant solely under volume-preserving diffeomorphisms. That characterization of UG has led to some confusion and incorrect statements in various treatments on the subject. For instance, sometimes it is claimed (mistakenly) that only spacetime metrics such that |det gμν
| = 1 can be considered as valid solutions of the theory. Additionally, that same (incorrect) statement is often invoked to argue that some particular gauges (e.g. the Newtonian or synchronous gauge) are not allowed when dealing with cosmological perturbation theory in UG. The present article is devoted to clarify those and other misconceptions regarding the notion of diffeomorphism invariance, in general, and its usage in the context of UG, in particular.
Small corrections to 1989 NIST constant-volume gas thermometry data
Authors: Harvey Allan H
Published: November 2023

Constant-volume gas thermometry data published in 1989 for the difference between the thermodynamic temperature and the International Practical Temperature Scale of 1968 are corrected in two ways. A refined estimate of the thermal expansivity of the material of the gas bulb, published in 1990, increases the thermodynamic temperature by amounts on the order of 1 mK–3 mK. Better knowledge of the nonideality of helium gas reduces the uncertainty of the nonideality correction to near zero and decreases the thermodynamic temperature by amounts on the order of 0.1 mK–0.5 mK. The net effect is a small increase in the thermodynamic temperature derived from the 1989 experiments. The magnitude of this increase is approximately 2 mK at 505 K, increasing to 3 mK at temperatures near 700 K, and then diminishing to near 0.5 mK at the highest temperature of the measurements (933 K). These corrections are smaller than the uncertainty of the experiments, but may be of significance for future recommendations for the relationship between the thermodynamic temperature and the consensus scale in this temperature range.
Collision avoidance of autonomous ships in inland waterways – A survey and open research problems
Authors: Tran Hoang Anh , Johansen Tor Arne , Negenborn Rudy R.
Published: November 2023

Promoting autonomous surface ships in inland waterways traffic (IWT) is a potential solution towards reducing road traffic and transport emission footprints. Over the last decade, there has been a growing research on autonomous ships for open waters. However, applying this research to the IWT domain is not straightforward. The IWT, due to its confined waterways, poses a different challenge than the open sea case. Due to the confined waterways, inland ships face several hydrodynamic phenomena that they rarely encountered in the open sea, such as shallow water, banks, or ship-to-ship effects. Furthermore, the higher traffic density in inland waterways also requires a different solution for sensing and control systems.

This paper offers an overview of the current developments on autonomous collision avoidance for inland waterway ships that covering different problems of safety navigation for ship in IWT. A short analysis is presented to highlight the strengths and weaknesses of each approach. We also discuss the current research gaps and what could be improved to enable the operation of inland autonomous ships.
Use Case Remote Pilotage – Technology Overview
Authors: Grundmann Robert , Ujkani Arbresh , Weisheit Jonathan , Seppänen Jedi , Salokorpi Mirva , Burmeister Hans-Christoph
Published: November 2023

Starting from a short study on pilotage transfers in terms of safety and sustainability as a motivation, this paper will draft trust requirements from pilots and navigators to remote based systems, before the capabilities of Extended Reality (XR) for these requirements are highlighted. This is followed by outlining the technical approach used within Sea4Value Fairway (S4VF) project and Remote Pilotage – Operational, innovative and Manageable Alternatives for Navigation routines (RePO MAN). The technical implementation within the context of the the use case method is explained and a consolidation of these use cases within the framework of RePO MAN and the possibility of adaptation in further field tests up to implementation is considered. Finally, limitations and deficits of remote pilot concepts will be outlined using the example of RePO MAN merged with the results of the S4VF project.
Real-time 360 degrees view for the operator of milliAmpere 2
Authors: Paasche Mathias Thoresen , Helgesen Øystein Kaarstad , Brekke Edmund Førland
Published: November 2023

In the evolving domain of autonomous marine operations, accurate perception and representation of the surrounding environment are crucial for safe and effective execution. This paper addresses this issue by developing and testing a near real-time 360-degree bird’s eye view system for the situations where the ferry, milliAmpere 2, has to be manually controlled by a local operator onboard. The goal was to aid the operator during the critical phase of docking, by displaying the surrounding area of the ferry from a bird’s eye view. The bird’s eye view was made by using inverse perspective mapping on the undistorted images from the 8 cameras onboard. The system was implemented in Python, and aimed to reach a run-time of less than 200ms. This goal was reached during the initial phase of the work. However, during live testing, only near real-time performance was achieved. Despite some shortcomings, the operators found the system to be a “useful additional assistance” during the docking process.
Generating Structured Set of Encounters for Verifying Automated Collision and Grounding Avoidance Systems
Authors: Pedersen Tom Arne , Vasanthan Chanjei , Karolius Kristian , Engelhardtsen Øystein , Houweling Koen Pieter , Jørgensen Are
Published: November 2023

It is a clear consensus in the maritime industry that ships, both conventional and with automated Collision and Grounding Avoidance (CAGA) systems, shall be navigated following the Convention on the International Regulations for Preventing Collisions at Sea (COLREG), ensuring a level playing field and a common understanding of the responsibilities between conventional and autonomous ships, allowing safe co-existence in the waterways. Simulation-based testing is expected to play an important role to explore and document safety and the ability to adhere to the COLREG, as it allows for rigorous testing of performance and failure handling before the software is installed on the ship. Many terms in COLREG used to specify acceptable behavior are qualitative, such as “ample time” and “apparent maneuver” and need to be viewed in light of a specific situation to be applied in practice. As the COLREG includes a large set of obligations specific to different types of situations, a significant number of ship encounters spread out across the different aspects of the regulations will be necessary to enable any judgments about the overall ability to adhere to these rules. The work presented in this paper provides a method and software toolbox for generating ship encounters to allow a systematic assessment of the vessel’s ability to act according to COLREG using simulation-based testing, and it is made freely available to vendors, students, or any other actors involved in the development or assurance of algorithms for automated collision and grounding avoidance systems.
Increased tower eigenfrequencies on floating foundations and their implications for large two- and three-bladed turbines
Authors: Anstock Fabian , Kessler Alois , Schorbach Vera
Published: November 2023

If the tower of a bottom-fixed turbine is put on a floating foundation, such as a spar, semi-submersible, or barge, its eigenfrequency increases. In the investigated case, the tower eigenfrequency rose to about twice its previous value. For bottom-fixed applications, the comparatively high blade-passing frequency of a three-blade turbine (3P) leaves a great bandwidth to design a light and soft tower with a low-enough eigenfrequency. On one of those floaters, however, the eigenfrequency of the same tower might neither be high nor low enough to avoid eigenfrequency excitation by 3P around rated speed. Due to the lower blade passing frequency of a two-bladed wind turbine (2P), the same tower eigenfrequency is high enough by default, enabling considerable material savings or at least eliminating the severe eigenfrequency excitation issue of its bottom-fixed version. Additionally, cost benefits in the whole life-cycle of two-bladed turbines remain. 20MW two- and three-bladed turbines were analyzed numerically on an upscaled version of the UMaine VolturnUS-S semi-submersible, confirming the reasoning.
The performance of two control strategies for floating wind turbines: lidar-assisted feedforward and multi-variable feedback
Authors: Guo Feng , Schlipf David , Lemmer Frank , Raach Steffen , Özinan Umut , Adam Raphaël , Choisnet Thomas
Published: November 2023

In this paper, we analyze the performances of two control strategies and their combination on a floating turbine through OpenFAST simulations. The floating wind turbine is modeled based on the demonstrative FLOATGEN, which consists of a 2MW wind turbine mounted on the Damping Pool platform designed by BW Ideol. The lidar-assisted control utilizes lidar wind preview to achieve blade pitch feedforward control. The multi-variable feedback additionally uses the platform pitch rate to determine blade pitch. By simulations with the above-rated wind and irregular wave conditions, both control strategies and their combination has the potential to reduce turbine vibrations. Especially, combining lidar-assisted control and multi-variable feedback control brings the most significant reduction in the standard deviations of rotor speed (>36%), low-speed shaft torque (>30%), and blade root moment (>15%).
New model for structural optimisation of airborne wind energy systems with rotary transmission
Authors: Wacker Jannis , McWilliam Michael , Muskulus Michael , Gaunaa Mac
Published: November 2023

Rotary Airborne Wind Energy Systems (RAWES) are networks of wings that act as flying wind turbines. The power extracted from the wind can be transmitted to ground-based generators through open tensegrity structures. In recent years, there have been different approaches to the topology of the Tensile Rotary Power Transmission (TRPT) and prototype designs are often driven by trial-and-error. This paper proposes a steady-state model with numerical optimisation to accelerate the development and prototyping of AWES by supporting the evaluation of new design concepts.

The coupled steady state model uses aerodynamics and structural dynamics to analyse the AWES performance. A novelty is, that the model includes both cross-wind pressure drag and axial friction drag acting on the tethers and frames in the tensegrity structure. Validation of the model has been achieved using data from field measurements of two prototypes.

In conclusion, using the proposed optimisation, RAWES with TRPT can be designed to maximise power density, coefficients of performance or power harvesting factor. While RAWES will not be able to outperform conventional wind turbines, they have the potential advantages in niche applications due to reduced costs and simplified logistics resulting from reduced material usage.
Numerical modelling of a hydro-pneumatic energy storage system for smoothing power fluctuations from offshore wind
Authors: Borg A , Sant T , Buhagiar D , Cutajar C , Farrugia R N
Published: November 2023

Energy storage systems are imperative in tackling the regulation of electricity supply and demand mismatch to avoid curtailment of wind energy. Co-locating energy storage in the same operating region as the offshore wind farms allows for an unobtrusive environment while also steering away from rising land prices. The presented work involves an offshore Hydro-Pneumatic Energy Storage (HPES) system made up of a subsea accumulator pre-charged with compressed air. The Energy Conversion Unit (ECU) of the system consists of a megawatt-scale hydraulic pump and a turbine. This paper discusses a novel numerical model developed in Python™ for simulating the operation of the ECU pump and turbine of the offshore HPES system by using a simple moving average, based on a time window of wind data, whilst also introducing a one-step-ahead forecasting model. The results of the research are split into two parts; Firstly, the analysis and validation of the Seasonal Auto Regressive Integrated Moving Average (SARIMA) forecasting model is performed. Secondly, results on the pump and turbine performance based on the smoothened power are shown. The research found that despite the centrifugal pump limitations due to variable head operation, a smoothened power output is efficiently (> 90 %) attained in retaining the intermittent power generated.
Optimising the operation of wind powered electrolysers
Authors: Ferguson J L B , Kervyn M , Nambiar A
Published: November 2023

Integrated wind power – hydrogen systems may make a useful contribution to achieving climate targets. Both centralised wind powered electrolysers and multi-MW decentralised solutions are likely to see multiple electrolyser units/systems deployed together. Since the efficiency of electrolysers is a function of their load factor, there is a possibility of optimising operation of the individual units in order to maximise the overall plant efficiency. Here we outline optimal strategies for electrolysis facilities with two, three and four independent units, and find that using these optimised strategies can increase annual wind powered hydrogen production by 2.3 - 3.8%, depending on the specific set up. By quantifying the increase in hydrogen production through using optimised control strategies, this research can help industry to identify the best overall control scheme for electrolyser plants composed of multiple units.
Design and control of all-DC offshore wind power plant with MMC-based DC/DC high-power converters
Authors: Follo Alessandra , Saborío-Romano Oscar , Tedeschi Elisabetta , Cutululis Nicolaos A.
Published: November 2023

This paper presents the modelling of an all-direct-current (all-DC) offshore wind power plant (OWPP) which employs DC/DC high-power converters based on modular multilevel converter (MMC) technology. A coordinated control strategy for such OWPP, designed to maximise the power output and maintain the DC voltages close to the nominal values, is also proposed. With the proposed strategy, wind turbines (WTs) are controlled to provide maximum power output according to a local maximum power point tracking (MPPT) reference signal together with a centralised curtailment signal. The response of the designed 600 MW all-DC OWPP is tested by means of dynamic simulations in MATLAB/Simulink.
Dynamic moisture diffusion in transformer winding insulation
Authors: Linhjell Dag , Mehammer Eirill Bachmann
Published: November 2023

Wind power production is intermittent due to varying wind conditions. This leads to frequent temperature changes in the wind farm transformers, which in turn affects the lifetime of the transformer winding insulation. To extend the lifetime through prediction of effects from dynamic loading, new models for degradation of insulation systems are needed. This article is laying the foundations of a model for dynamic moisture migration in the winding insulation of wind farm transformers. Relevant equations and approximations are presented and an experimental setup for laboratory testing of transformer insulation ageing related moisture migration under dynamic loading is described. The demonstration experiment clearly shows moisture migration through paper layers in a simple physical winding insulation model. As the ageing of cellulose is very moisture-dependent, the migration should clearly be included in models of ageing under dynamic load.
Second-order wave loads on floating wind parks with shared mooring
Authors: Sauder Thomas
Published: November 2023

Wave loads on lattices of marine structures, such as wind parks with shared mooring systems, are considered. Modal excitation induced by second-order low-frequency wave loads is derived, leading to modal quadratic transfer functions. The consequence for the modal loads, of applying Newman’s approximation is investigated.
Maritime logistics optimisation for predictive maintenance at offshore wind farms
Authors: Halvorsen-Weare Elin Espeland , Nonås Lars Magne
Published: November 2023

For offshore wind farms, a move from a preventive and corrective maintenance regime to a predictive maintenance regime requires new methods for modelling approaches for maritime logistics planning. This paper presents an overview of the maritime logistics planning problem for a predictive maintenance regime and introduces the current state-of-the-art for operational research in the field of operation and maintenance at offshore wind farms. Findings are that a combination of the vessel resource scheduling problem for operation and maintenance at offshore wind farms with predictive analysis and digital twins is a promising future research step. A framework for a decision support tool is presented that will help bridge the gap, both with respect to the academic path, and the gap between academic research and industry.
Design Optimization of Floating Offshore Wind Turbine Substructure Using Frequency Domain Modelling and Genetic Algorithm
Authors: Benifla Victor , Adam Frank
Published: November 2023

Floating offshore wind turbines are becoming increasingly popular as a promising technology for producing cleaner energy. However, in order to be competitive with fixed offshore wind projects or even onshore wind projects, the costs associated with floating offshore wind turbines must be significantly reduced. To tackle this challenge, this paper presents a comprehensive framework for optimizing the design of floating offshore wind turbine substructures and their components. The innovative open-source frequency-domain dynamic model RAFT is used to take into account the aerodynamic, hydrodynamic and mooring forces that impact the stability and dynamics of the floating system. The numerical model is coupled with an efficient genetic algorithm to minimize the structural mass of the floating platform while maintaining its stability and dynamic performance. The geometrical parametrization of the substructure, the implementation of the numerical model, and the overall optimization process are all thoroughly detailed in this paper, along with preliminary results that demonstrate the potential cost reductions that can be achieved through this framework.
A Reinforcement Learning framework for Wake Steering of Wind Turbines
Authors: Lye Kjetil Olsen , Tabib Mandar V , Johannessen Kjetil André
Published: November 2023

Ideally, optimum power for a single turbine is obtained when the wind-turbine is aligned with the wind direction. However in multi-turbine wind-farm set-up, wake effects lead to decreased power production from downstream turbine [1, 2, 3, 4, 5]. Hence, a control strategy based on wake steering involves misalignment of upstream turbines with the wind direction causing their wakes to deflect away from downstream wind turbines needs to be investigated. A great deal of work has been put into dynamically controlling the orientation of the individual wind turbines to maximize the power output of the farm [6, 7, 8, 9]. In the wake-steering based control, the misaligned wind turbines produce less power, while the performance of downstream turbines gets enhanced which increases overall net power gain for the wind power plant. Traditionally, the benefits of wake steering have been demonstrated assuming fixed wind directions (e.g., using high-fidelity modeling). Amongst the most recent techniques, particularly promising is the use of Reinforcement learning (RL), which is a branch of machine learning where models are trained to make decisions based on observations of their environment. It is a flexible framework for devising strategies for solving optimal control problems in a broad range of applications across the sciences. Early attempts at using Reinforcement learning for wake steering have been carried out [7, 8, 9], and show promising results. In practice, however, wake-steering controllers must operate in dynamic wind environments in which the wind conditions are estimated from imperfect measurements. Hence, a reinforcement learning framework is developed in this work for dynamic wind conditions. The results show that the framework is promising, and we compare the deep reinforcement learning approach against a considerably more expensive traditional optimization approach which serves as a good baseline. Future work could include looking at more realistic wake models, steering in the presence of noisy observations, and incorporating weather predictions.
Techno-economical Layout and Turbine Type Optimization for Floating Offshore Wind Farms: A ScotWind Portfolio Study
Authors: Martin Joanna , Moreno Carlos Pérez , Snedker Thor Heine , Dykes Katherine , Bayati Ilmas
Published: November 2023

This paper explores state-of-the-art modelling and optimization methods for floating offshore wind farms. A case study is performed on three ScotWind lease areas, where the optimal turbine type and layout is assessed in terms of Annual Energy Production (AEP) using a multiple-step optimization strategy. The numerical setup relies on TopFarm (DTU), ORBIT (NREL) and Peak Wind’s in-house codes and expertise. The portfolio study reveals that across all sites, using wind turbines of higher single capacity (15MW against 11MW and 14MW) is more optimal, as the scaling-up of the nameplate power allows to save costs. The LCOE decreases to around 100$/MWh, which is consistent with the predictions for commercial floating wind projects in the coming years. The optimal layouts show an alignment of the turbines perpendicularly to the prevailing wind direction, in which their spacing is also greater to minimize the wake losses. Sensitivity analyses are carried out on key project-specific parameters and optimization inputs, such as the initial positions of the turbines, showing how a multiple-start strategy explores the whole design space and allows to validate the optima found.
Experiments on the wake flow behind different configurations of multirotor wind turbines
Authors: Jørs Andreas Grodås , Mjåtveit Torbjørn Lavik , Skoland Morten , Stenfelt Gloria , Hansen Thomas , Bartl Jan
Published: November 2023

Multirotor wind turbine concepts have recently emerged as a promising alternative to conventional turbines. When arranged in farms, the wake flow behind multirotor assemblies becomes an important factor in the cost-of-energy equation. This paper presents a lab-scale experiment on the effect of rotor number, inter-rotor spacing and yaw-misalignment on the wake development behind a simplified multirotor model. The flow characteristics are investigated by towing different arrangements of porous discs in a large water tank while traversing an Acoustic Doppler Velocimeter in the wake. Results show lower initial velocity deficits in a multirotor’s near wake, whereas its far wake is observed to be similar to the one of a single rotor. The wake’s recovery rate is first stimulated by additional shear stresses in between the single rotors, while flattening off further downstream. Measurements on the wake flow behind individual yaw on the single rotors compared to collective yaw on all rotors show a similar deflection of the mean velocity deficit in the wake.
A FAST.Farm and MATLAB/Simulink interface for wind farm control design
Authors: Smits Coen-Jan , Silva Jean Gonzalez , Chabaud Valentin , Ferrari Riccardo
Published: November 2023

Increasing the efficiency of wind farms is important for speeding up the transition from fossil fuels to renewable energy sources. Current wind farm control relies on maximization of power generation of individual turbines. However, research has demonstrated that plant-wide wind farm control could optimize the performance of a wind farm. Wind farm simulation tools are crucial in designing, testing, and validating wind farm controls. FAST.Farm is a recently developed multi-physics engineering tool for modeling wind farm performance by solving the aero-hydro-servoelastic dynamics of each individual turbine. The capabilities of FAST.Farm for control design purposes can be extended through a co-simulation with MATLAB/Simulink. Therefore, a MATLAB/Simulink interface with FAST.Farm has been developed. The creation and operation of this interface are explained in this paper. This interface supports developing and testing advanced closed-loop control at the wind turbine and wind farm levels.
Dependence of mechanical properties of electroporcelain on quartz particle size subjected to cyclic tests
Authors: Al-Shantir O , Ruokanen M , Vrabec M , Csáki Š , Mikušová D , Lukáč F , Trník A
Published: November 2023

The aim of the paper is the reveal effect of the quartz particle size on the mechanical properties of the electroporcelain subjected to cyclic test. This paper describes the influence of quartz on the mechanical properties of electroporcelain. The amount of quartz was controlled during sample preparation. Eight groups of samples were manufactured by extrusion with the addition of 0, 1, 2, and 4 wt.% of quartz and two different quartz grain sizes of 200 μm and 64 μm. Samples were fired at the temperature of 1320 °C, which is a common temperature for this type of ceramics. Once the nominal value of mechanical strength for each group was determined, the samples were cyclically tested using 50% of the nominal mechanical strength. The samples were tested by a 3-point bending machine for obtaining mechanical strength. The obtained values exhibited, that with an increasing amount of quartz, the mechanical strength decreased. On the other hand, the amount of quartz did not have a significant impact on cyclic tests. The influence of the amount of quartz on the value of mechanical strength after 100 and 500 cycles was negligible. However, the quartz grain size had a significant effect on the mechanical strength. The smaller grain size of impurities led to a lower degradation effect.