bluuebunny/crossref_metadata_2025 huggingface dataset:
Analisa Kelayakan Finansial Investasi Sistem Pengisian Listrik Umum di Kecamatan Muara Jawa Kukar
Authors: Sriwardaya Yuman Amirun , Kristiana Dian
Published: September 2023

Electricity has become basic need must be fulfilled for a better life in community, including public street lighting. Mainly those who live in the alleys and away from the main road. The responsibility for procurement, management and maintenance of Public Street Lighting infrastructure lies with the respective regional governments. However, the capability of each region to fulfil this need varies, as a result there are still areas that do not have adequate public street lighting. Researchers saw this need therefore initiate the establishment of public street lighting in collaboration with the community on an independent basis with PT PLN as the SPLU provider. SPLU lighting and multi-purpose services established to answer the needs of the community, namely the ease of getting electricity for adequate public street lighting in alleys that are not yet reached by PJU and to serve socio-cultural activities in the community. The purpose of this research is to support community need for public lighting without neglecting the feasibility of investment from perspective of finance using the parameters Net Present Value (NPV), Profitable Index as well as calculating the Payback Period (PP). By this research, with initial outlays Rp 49,236,400, this project was found that the NPV is Rp 827,856,656, PI 17.8 which means both positive.  The investment cost can be returned/payback period after 4 months only. This means that investing in providing SPLU facilities in the area of Subdistrict Muara Jawa Kukar is feasible
Kualitas Soft Skill Mahasiswa Trainee Departemen Front Office pada Hotel Bintang Empat di Kota Bandung
Authors: Hidayah Rismawati , Octaviany Vany
Published: September 2023

Hospitality students are required to have skills to be successful in a competitive hospitality industry with high demands and competition among workers and prospective workers. Hospitality students are prepared to be professional and skilled in the hospitality field, specifically in the front office department. The skills required in the front office department are not only hard skills but also soft skills. Hospitality students are strongly related to Human Resources (HR) because hospitality is a service industry that indeed depends on the quality of HR. Thus, those skills are necessary to be owned by students who currently work or will work in the hospitality industry, especially in the department, because it really requires quality workers to ensure satisfaction and maximize the services for the guests. In determining the soft skill qualities owned by the hospitality students in the front office department, there are five indicators as reference: work ethic, courtesy, cooperation, discipline or self-confidence, and adjustment to norms. This research used the qualitative approach method. The data collection technique was conducted by interviewing the Human Resources Department (HRD) and hospitality students who currently work or have worked in the front office department of a four-star hotel in Bandung
Peningkatan Produktivitas Kerja Melalui Rotasi Jabatan
Authors: Sunarya Thia Kharin Fauziah , Octaviany Vany
Published: September 2023

The productivity of employees at The Jayakarta Suite Hotel & Resort Bandung has experienced a decline, necessitating a job rotation to enhance work productivity. This study aims to explore work productivity and job rotation, as well as the role of job rotation in improving work productivity at The Jayakarta Suite Hotel & Resort Bandung, particularly in the F&B Service department. This research employs a qualitative ethnographic approach. Data collection techniques involve interviews, observations, and documentation of HRD, F&B managers/supervisors, and F&B employees at The Jayakarta Suite Hotel & Resort Bandung. The findings of this research indicate that job rotation has positive effects on the company and employee career progression, yet its implementation has not proven effective in boosting work productivity. Older employees, being the majority, feel comfortable in their current positions and show no interest in job rotation. Efforts to enhance work productivity can be accomplished through skills upgrading, job evaluations, and focusing on physical factors.
Organ and Cadaver Donation; Student Opinions from Different Cultures.
Authors: Nalbant Asrın , Uzuner Muhammed Bora , Kurbetli Nuriye
Published: September 2023

Objective: Despite organ donations, the need for organs is increasing daily, and efforts to increase organ donation continue without slowing down. Cadaver donation, necessary for medical education, is an issue waiting to be supported worldwide. In our study, a questionnaire was applied to measure the knowledge and attitudes of Turkish and international students toward organ and cadaver donation. Material and Methods: A total of 305 students, including 236 Turkish citizens and 68 international students, participated in the study. Students accessed the prepared questionnaires via a Google form. Results: It was determined that there was a statistical difference between Turkish and international students regarding their knowledge about organ donation compared to cadaver donation (Turkish students 78.8 % (n=186) yes, international students 57.,4 % (n=39) yes). In the social circles of Turkish and international students, organ donations were more common than cadaver donations, and a statistically significant difference was found for both groups (Turkish students 42.8 % (n=101) yes, international students 48.5 % (n=33) yes). The reasons for donating their bodies (Turkish students 48.3% (n=114) ''For use in organ transplantation'', international students 35.3 % (n=24) ''Because your body is useless after death and decays''), and organs (Turkish students 35.6 % (n=84), international students 32.4 % (n=22) ''For use in organ transplantation'') of Turkish and international students differed significantly. Conclusion: Based on the answers given by the students, it has been concluded that donations will increase when information is provided about the importance of organ and cadaver donation.
Designing Greedy Algorithm for Cyber Threat Detection
Authors: Manas Kumar Yogi  , Dwarampudi Aiswarya
Published: September 2023

As the digital landscape continues to expand, the complexity and frequency of cyber threats targeting critical information systems also increases. Effective cyber threat detection has become a paramount concern for safeguarding sensitive data and ensuring the uninterrupted operation of various infrastructures. This research introduces a novel approach to cyber threat detection through the design of a greedy algorithm tailored for identifying specific types of threats. The algorithm focuses on a simplified aspect of threat detection, aiming to highlight the potential of greedy algorithms in contributing to the broader field of cybersecurity. The methodology involves monitoring network traffic for signs of port scanning activity, a common precursor to potential cyber-attacks. The algorithm's effectiveness is evaluated in terms of its ability to accurately identify suspicious scanning behavior while minimizing false positives. By presenting this algorithmic framework, the research aims to contribute to the ongoing efforts in enhancing cyber threat detection techniques.
Electronic Health Record Management System using RFID: Improving Efficiency and Accuracy in Healthcare
Authors: Pandey Gobinda , Sunar Akash , Yogi Jagdish , Poudel Navaraj , Koirala Khem Raj
Published: September 2023

This research presents the development and implementation of an Electronic Health Record Management System (EHRMS) using Radio Frequency Identification (RFID) technology. The study discusses the limitations of traditional paper-based health record systems and highlights the benefits of integrating RFID technology in healthcare settings. The EHRMS streamlines patient identification and data capture processes, enhances data accuracy, and improves overall healthcare delivery. Real-time synchronization ensures up-to-date and easily accessible patient records, empowering healthcare providers to make informed decisions and provide timely interventions. The paper concludes with the potential impact of the RFID-based EHRMS in transforming healthcare record management and improving patient outcomes.
PREPARATION OF EDUCATORS OF PRESCHOOL EDUCATION INSTITUTIONS FOR THE IMPLEMENTATION OF HEALTH-SAVING TECHNOLOGIES BY MEANS OF PHYSICAL CULTURE IN CULTURE
Authors:   Oleksandr Dovzhenko Glukhiv National Pedagogical University, Kuzminskyi Anatoliy , Chychuk Antonina ,   Ferenc Rakoti II Transcarpathian Hungarian Institute, Kuchai Oleksandr ,   National University of Life and Environmental Sciences of Ukraine
Published: September 2023

The article discusses the importance of introducing health technologies through physical education in preschool institutions. The essence of preparation of the educator of preschool institution for realization of health-preserving technologies and formation at children of a healthy way of life by means of physical culture is opened. Forms, methods and means of achieving the above goal, which must be mastered by a future educator of preschool education in the process of studying in a higher education institution of pedagogical profile. The main indicators of the child's physical health – the hardening of the body (the degree of development of the body's adaptive capabilities against adverse environmental changes); full physical development; level of motor readiness; development of physical qualities and fitness of the body. The effectiveness of hardening of children is determined by the appropriate selection of its various types (wiping, dousing with cold water, contrast dousing, walking barefoot, gargling, etc.). The key to qualitative changes is regularity, consistency, a positive attitude of the child to hardening procedures, the absence of coercion. The priority directions of physical culture and health work in the educational institution are written down. One of the important tasks of a higher education institution that trains educators for preschool education institutions is to train future professionals to implement health technologies by means of physical culture in professional activities. During the training, the teacher-educator must master various forms of work on physical education with preschool children. He must know what conditions must be created for the holistic development of the child with the implementation of health technologies, including means of physical culture.
Efektifitas Variasi Konsentrasi Ekstrak Kulit Pisang Raja (Musa Paradisiaca var. Raja) Sebagai Biolarvasida Culex Sp.
Authors: Oetami Leiylla Kurnia  , Aries Prasetyo  , Tuhu Pinardi  , Djoko Windu P. Irawan
Published: September 2023

Mosquitoes are vectors of disease and nuisance animals where Culex Sp mosquitoes are vectors of filariasis or elephantiasis. Vector control that has been carried out by the community generally uses chemical insecticides where if the use of chemical insecticides is carried out in the long term and continuously it can cause side effects on the environment, besides that it also causes resistance to the vector itself. This study aims to determine the effectiveness of the peel extract of plantain (Musa Paradisiaca var. Raja) as a larvicide on the mortality of Culex Sp. larvae. This research is an experimental research with The Static Group Comparassion Design. Total population and samples were 600 Culex Sp instar III larvae. The sampling method used random sampling method on Culex Sp instar III larvae or at the age of 3-4 days. Data analysis using Anova analysis using the STATA application. The results of the Anova test showed that there were differences in the mortality of Culex Sp with various doses of plantain peel extract (Musa Paradisiaca var. Raja), the highest effectiveness was 84% with an average mortality of 21 Culex Sp larvae, the conclusion of the study from probit analysis with an LC50 (Lethal Concentration) value of 2,969% and the most effective dose to kill Culex Sp larvae was at a dose of 8%.
Effects of projected wave climate changes on the sizing and performance of OWCs: a focus on the Mediterranean and Atlantic European coastal waters
Authors: Simonetti Irene , Cappietti Lorenzo
Published: September 2023

Reliable estimations of the Annual Energy Production (AEP) achievable with a certain Wave Energy Converter (WEC) are among the fundamental elements for a sound evaluation of the related Levelized Cost of Energy (LCOE) that plays a crucial role in the investment decision-making process. The lack of reliability in estimates of the device productivity can be a result of the uncertainty in the assessment of the available wave energy resource since the geometry of the device which maximizes the AEP is dependent on the specific wave climate at the foreseen installation site.

The Climate Data Store of the Copernicus Climate Change Service delivers projections of the wave climate along the 20 m bathymetric contours of the whole European coastlines, covering the period 2040-2100, under two Representative Concentration Pathway (RCP) scenarios (RCP4.5 and RCP8.5) [1].

This work addresses the effect of such long-term wave climate changes on the optimal sizing and performances of Oscillating Water Column (OWC) WECs to be installed along the Atlantic European coastline, expanding a previously published work in which the Mediterranean coastline was investigated [2]. The capture width of the OWC WEC under different wave conditions is computed using an empirical model [3] capable of predicting the device performance with acceptable accuracy and limited computational time.

The results show that the optimal geometry of the OWC WEC varies significantly in the different geographical locations, and that the long-term changes in the wave energy resource could cause a slight modification of the optimal geometry in each potential installation site. The AEP of the OWC WEC in the projected wave climate scenario can be significantly different compared to the present one, potentially contributing to reducing the LCOE of this wave energy conversion technology in some geographical locations.

REFERENCES:

[1] Caires, S., Yan, K., 2022. Ocean surface wave time series for the European coast from 1976 to 2100 derived from climate projections. (Accessed on Feb. 2022) DOI: 10.24381/cds.572bf382. Copernicus Climate Change Service (C3S) Climate Data Store (CDS)

[2] Simonetti, I., Cappietti, L., 2023, Mediterranean coastal wave-climate long-term trend in climate change scenarios and effects on the optimal sizing of OWC wave energy converters, Coastal Engineering, 173, 104247.

[3] Simonetti, I., Cappietti, L., Oumeraci, H., 2018. An empirical model as a supporting tool to optimize the main design parameters of a stationary oscillating water column wave energy converter. Appl. Energy 231, 1205–1215.
Integration of wave energy into Energy Systems: an insight to the system dynamics and ways forward
Authors: Lavidas George , Delgado Elizundia Felix , Blok Kornelis
Published: September 2023

Wave energy is a rich and highly accessible renewable energy resource, that has largely been under-developed. Studies from the sector have tried to show the potential of benefits wave energy in “simple cases” or via small hybrid systems, the large scale incorporation of wave energy has not yet been fully investigated. Our approach uses a fully dynamic climate driven energy system model, which has undergone modifications to include wave energy converters and their associated dependencies.

This study explores the system dynamics and important elements that will be used for large scale wave energy integration; in a fully coupled European Energy System. We explore the cost pathways of different wave energy converters, the impact of climate data, and the impact of transmission capacity expansion under cost-optimal configurations of a multi-renewable European power system. From this preliminary approach we aim to provide the boundary conditions, and assumptions that will govern the integration of wave energy into the European Energy System up to 2050.
Investigation on the extreme peak mooring force distribution of a point absorber wave energy converter with and without a survivability control system
Authors: Shahroozi Zahra , Göteman Malin , Engström Jens
Published: September 2023

To determine the optimal design of the wave energy converter (WEC) that can withstand extreme waveconditions, the short- and long-term extreme responses of the system need to be determined. This paper focuses on the extreme peak force distribution of the mooring force for a 1:30 scaled point absorber WEC. The basis of this analysis is the mooring force response obtained from a WEC-Sim model calibrated by wave tank experimental data. The extreme sea states have been chosen from a50-year environmental contour. Here, first, the long-term extreme response using the full sea state approach is obtained for three constant damping cases of the power take-off (PTO) system. Then, using a contour approach, the expected value of the extreme peak line (mooring) force distribution is computed for the sea states along an environmental contour. Further, for the most extremesea state, the extreme peak line force distribution is also computed where a survivability control system, based on a deep neural network (DNN), changes the PTO damping to minimize the peak mooring force in each zero up-crossing episode of surface elevation. The results show that in the absence of a control system, the zero PTO damping case is a conservative choice in the analysis of the long-term response and the design load. For the most extreme sea state along the environmental contour, the survivability control system slightly reduces the expected value of the extreme peak force distribution when compared with lower constant PTO damping configurations.
Wave Amplification inside an Open Circular Caisson for Wave Energy Conversion in Waters with Medium Energy Density
Authors: Chen Jiahn-Horng
Published: September 2023

Wave energy is one of important marine renewable energy resources. Many studies have been devoted to harnessing the energy for human use. Though they are almost everywhere in the sea, waves can be much more significant in some sea areas than others. For example, the wave energy density in Asian waters is usually much less than that in European west coasts.

To make the wave energy harvesting more viable in Asian waters with medium wave energy density, we propose to employ an open caisson to amplify the wave locally and to combine it with a wave energy converter to tap the amplified wave energy. In this study, we focus on the effect of incident wave height on the amplification factor which is defined as the ratio of the wave height inside the caisson to that of the incident wave. Shown in Figure 1, the caisson is mounted vertically on the horizontal seabed in the open sea. At the edge of the opening, it has two guides on the two sides of the opening. They are identical in geometry and part of a solid cylinder. The purpose of the two guides is to enhance the wave amplification inside the caisson.

The study was conducted primarily by CFD computations and partially verified by experiments. In computations, the finite volume method was employed to discretize the Navier-Stokes equations. A multi-block grid was generated for computational purposes. The volume-of-fluid (VOF) method was used to capture the free surface. The nonlinear iterations were conducted with the PISO method. And the implicit time marching scheme was adopted in the time direction. It is interesting to find that the amplified wave height in the caisson is not linearly related to the incident wave height. Furthermore, the amplification factor is also a function of the incident wave period. The wave period at which the peak value of the amplification factor appears is insensitive to the wave height. The amplification factor is usually greater than unity for a wide range of incident wave period.
Evaluating the performance of turbulence closure models for tidal stream resource characterization
Authors: Yang Zhaoqing , Deb Mithun
Published: September 2023

Harvesting tidal stream energy from the ocean for electricity generation has been considered as an energy resource alternative to fossil fuels for mitigating the negative impact of climate change and enhancing energy security and coastal resilience. Numerical models have been used extensively to characterize and assess tidal resources at potential tidal energy development sites. Turbulence plays an important role in site selection and tidal turbine farm deployment. However, most of the numerical modeling studies for tidal energy resource characterization do not include turbulence characteristics because of the limitation of Reynolds averaged Navier–Stokes coastal ocean model in resolving the inertial sub-range turbulence scales. However, studies also demonstrated that turbulence properties, such as turbulence intensity and turbulence kinetic energy, simulated by the coastal ocean models based on turbulence closures can be useful in assisting tidal resource characterization at tidal energy sites. In this study, we evaluated four General Ocean Turbulence Model (GOTM)  turbulence closure models implemented in a tidal hydrodynamic model –Finite Volume Community Ocean Model (FVCOM)  to characterize the tidal energy resource in the Western Passage, Maine, USA – a top ranked tidal energy site. The four turbulence closure models used in this analysis are k–kl (Mellor–Yamada Level 2.5), k-ε, k–ω, and a generic model. Model sensitivities showed that the MY2.5 model performed the best in comparison with the field measurements. In particular, the simulated time series of turbulence intensity and kinetic energy matched the observed data very well in the Western Passage. Detailed analysis was conducted to characterize turbulence properties on the horizontal plane and at selective cross-sections. This study demonstrated that turbulence properties simulated by a coastal ocean model, along with tidal hydrodynamic properties, can be very informative for tidal energy resource characterization and project site selection, as recommended by the International Electrotechnical Commission (IEC) technical specifications (IEC TS 62600-201).
Wave Energy Power Take-off Validation with a Hydraulicly Actuated Rotary Dynamometer and a Bi-directional High-power DC Supply
Authors: Nichols Casey , Lambert Scott , Fao Rebecca , Raye Robert
Published: September 2023

There are many organizations working towards the commercialization of wave energy converter technologies and are advancing their designs through the technology readiness levels (TRLs). A critical step before the field deployment of prototype wave energy converters is the validation of the subsystems and components that are contained in the wave energy converter through laboratory testing and performance characterization. In 2021, the National Renewable Energy Laboratory (NREL) developed and demonstrated a system for testing power takeoffs (PTO) with a low-speed, high-torque dynamometer and a grid-tied high-power DC power source and sink before field deployment. The hydraulic dynamometer allows for the simulation of PTO actuation from wave motion and is capable of a wide range of wave periods and heights which are represented as various speeds and torques from the dynamometer. The high-power bidirectional power supply allows for hardware in the loop and controller in the loop testing to be conducted on WEC power electronics. This presentation was made to describe the methods used by NREL research staff to test all components and sub-systems in the PTO of a novel wave energy converter before field deployment.
Structural testing and numerical modelling of a glass fibre-reinforced composite demonstrator for turbine blades
Authors: Jiang Yadong , Finnegan William , Kelly Conor , Bastawisy Ahmed , Flanagan Tomas , Glennon Conor , Goggins Jamie
Published: September 2023

Tidal energy, a clean, predictable and reliable renewable energy source, can play an important role in creating a carbon-free energy system in Europe. The cumulative tidal stream technology deployed in Europe was 27.9 MW in 2020, which contributes to 77% of the global total tidal energy device installations. Under a high growth scenario, about 2388 MW of tidal energy capacities will be deployed in Europe by 2030. The structural performance of a tidal turbine blade is vital as it guarantees the safe operation of a turbine within its lifespan in marine environments. Experimental testing is a reliable way of investigating the structural performance of a tidal turbine blade. In this research, the structural performance of a composite demonstrator is carried out. The 5-m long demonstrator represents a tidal current turbine’s spar cap, the strongest region of a typical rotor blade. The demonstrator consists of two spar cap and two webs, which are manufactured with glass-fibre reinforced composite materials. Steel inserts are drilled into the root of the spar cap to connect to the support frame. A hydraulic actuator is used to apply loading to the tip region of the demonstrator to simulate the operation loading. Instrumentations, including strain gauges, accelerometers and displacement transducers, are installed to monitor the demonstrator responses. Besides testing the demonstrator, the mechanical properties of the glass-fibre reinforced composite material are also obtained through coupon tests. The test results are utilised to develop a finite element model, which will be used in the blade design and optimisation case study in the future.
Acoustic Characterization around the CalWave Wave Energy Converter
Authors: Raghukumar Kaustubha , Heal Katherine , Chang Grace , Spada Frank
Published: September 2023

Sound generated by marine energy (ME) installations in the ocean environment remains a particular concern for environmental permitting despite the limited evidence showing low levels of ME sounds relative to other anthropogenic sounds. In an effort to increase understanding of potential environmental effects of marine energy projects and help reduce barriers to marine energy deployments, a new acoustic monitoring technology, the NoiseSpotter®, was developed and recently demonstrated around CalWave’s operational scaled xWave™ wave energy converter (WEC). The NoiseSpotter® improves upon traditional acoustic sensing techniques by use of a cost-effective, compact array of acoustic particle velocity sensors that characterizes, classifies, and provides accurate location information for anthropogenic and natural sounds in real time.
Results are presented from co-deployments of NoiseSpotter® with the operational CalWave WEC that were conducted over a 9-day period in fall 2021 offshore of Scripps Research Pier in San Diego, California, USA. The multi-day deployment of the NoiseSpotter® at 100 m from the CalWave WEC revealed a rich library of sounds that include:

Low-level (~95 dB re 1 µPa relative to an ambient noise floor between 80-90 dB re 1 µPa) sounds from the WEC associated with the deliberate actuation of mechanical components,
Sounds from a hovering helicopter,
Marine mammal vocalizations, and,
Small boat engines.

Sound levels from the WEC were placed within the context of ambient sounds, and reveal little deviation from the ambient soundscape. The azimuthal anisotropy of WEC sound was investigated via deployments along four cardinal directions around the WEC. While a noticeable increase was observed along the north-south orientation, the sound levels along all directions still showed little deviation relative to the ambient noise floor. Analysis of low-level WEC sounds in conjunction with exploratory machine learning techniques demonstrate the utility of directional acoustic sensing in distinguishing marine energy sounds from the myriad other sounds in the surrounding ocean environment.
Actuator-Line CFD Simulation of Tidal-Stream Turbines in a Compact Array
Authors: Apsley David
Published: September 2023

An actuator-line CFD model is used to simulate tidal-stream turbines acting alone or in a compact 3-turbine staggered array. CFD results confirm that the accelerated bypass flow between two proximal turbines in shallow water can enhance the power output for a close downstream turbine, with additional smaller effect of the upstream turbines’ operating point. Comparison with other authors’ experimental data in a narrow flume (IFREMER) and circular wave-current tank (FloWave) show some difference in relative loads between the turbines, possibly associated with ambiguity in overall blade pitch and difficulty in characterising onset flow in the FloWave tank. The accelerated bypass flow is persistent and largely established on the rotor plane of the upstream turbines, indicating how local array effects might be incorporated in simpler blade-element/momentum-theory design tools.
Feasibility of wave energy harvesting in the Ligurian Sea
Authors: Corrales González Manuel Alejandro , Lavidas George , Besio Giovanni
Published: September 2023

A series of short and mid-term guidelines have been established due to the pursuit to offer clean energy and reduce the environmental impact in the Mediterranean and European environment. Currently, the scientific community and the industrial sector promote to find new technologies and means to achieve these regulations. Efforts to provide sustainable ways to supply electricity in Italy have led to the exploration of marine renewable energies (MRE) in the Mediterranean Sea. In particular, in the Ligurian Sea, where the wave climate can provide one of the higher energy sources, represents an optimal opportunity for supplying this energy resource to coastal cities. However, the wave conditions are not as significant as those in other marine regions around the world. There are several devices currently developed which can be applicable to the region. Hence, an evaluation from a technical and economic perspective is advised. Additionally we also investigate the scaling and survival considerations for Wave Energy Converters (WECs) when facing extreme storm events. The proposed study offers the evaluation of a sustainable alternative for powering the electricity mix in the Liguria region, through the exploitation of the wave energy resource. Attractive findings emerge after the assessment of eight floating-body wave energy converters.
Graphene oxide reinforced room-temperature-vulcanising elastomers for flexible wave energy converters
Authors: Wang Xinyu , Meng Maozhou , Cox Malcolm , Puzhukkil Krishnendu , Yang Jingyi , Borthwick Alistair , Ransley Edward , Cheng Shanshan , Chaplin John , Hann Martyn , Rawlinson-Smith Robert , Zheng Siming , You Zhong , Greaves Deborah
Published: September 2023

Rubber products are widely used for marine applications, such as fenders, bumpers, ship launching airbags, and hovercraft skirts. Many of these products are made through a vulcanising (crosslinking) process where large-scale tooling for high-temperature and high-pressure moulding is required. The cost will be greatly magnified when manufacturing large-scale components, such as flexible parts for next-generation wave energy converters. Two-part polyurethane rubber (PUR) is a room-temperature, low-pressure curing alternative that could minimise manufacturing costs. However, the general inferior mechanical performance of such room-temperature-vulcanising (RTV) rubber (compared to vulcanised rubber) restricts the application of PUR in the marine industry. It has recently been reported that the addition of graphene oxide (GO) could significantly improve the internal bonding of polymer elastomers and thus provide better mechanical performance with a low filler loading. In the work presented in this paper, different types of silane coupling agents (SCA) were used to treat the surface of GO, and the potential application of PUR/GO composites under marine environments and their mechanical performance were investigated. More than 75 % increases in tensile strength were observed after 1 wt % of GO was added. Moreover, a significant reduction in water absorption occurred during the seawater immersion test. It is suggested that hydrophobic sites provided by silane coupling agents play an important role on the GO surface, where polar groups, such as hydroxyl and carboxyl groups, were replaced during the silane treatment.
High-fidelity modeling of a vertical axis tidal turbine model under realistic flow conditions
Authors: Grondeau Mikaël , Guillou Sylvain
Published: September 2023

In the context of the global energy crisis, developing renewable energies is of primal importance. Among the renewable resources available are tidal currents. Tidal currents can be exploited with tidal turbines. Different concepts of tidal turbine exist, we here investigate a vertical axis tidal turbine or VATT prototype made by HydroQuest and CMN. More precisely, we carry on numerical investigations on a Hydroquest/CMN tidal turbine model.
Experimental studies are limited to turbine models and thus suffer from scale effects. In situ measurement are still expensive and difficult to acquire. Computational Fluid Dynamics (CFD) is an interesting alternative in order to go beyond what experiments can offer. One major drawback of CFD is that it requires validation of the models used. A validation of our CFD tool is included in this paper. Because the hydrodynamic of vertical axis tidal turbines is highly unsteady, Large Eddy Simulation (LES) are well adapted here.
Blade-resolved Computational Fluid Dynamics (CFD) approaches are appropriate to study vertical axis tidal turbines, but their cost is still prohibitive for real size tidal turbine. Simplified approaches are preferred solutions. Literature showed that Actuator Line Model (ALM) LES is well suited to model vertical axis turbine.
Most tidal sites are characterized with strong turbulence intensities. The presence of turbulence in most tidal sites has led companies and academics to study the effects of ambient turbulence over tidal turbines. It has been shown that turbulence can have a non-negligible influence on the turbine performances and wake. To account for the effects of turbulence, synthetic turbulence is introduced at the inlet of the simulation.
The LBM is an unsteady weakly-compressible CFD approach. It solves the Boltzmann equation using an explicit time discretization and a uniform Cartesian grid called lattice. It has been proven to be an efficient approach for modeling tidal turbines using LES and ALM, Grondeau et al. (2019).
In this paper, we study a tidal turbine model of the Hydroquest/CMN VATT using an ALM-LBM-LES approach. This model was tested at the Ifremer Boulogne-sur-Mer testing facilities. We first compare our results with the experimental ones in a scenario without turbulence and for flood and ebb tide configurations. A numerical investigation of the influence of upstream turbulence on the turbine performances and wake is then realized. Prospects of this study include among others the effects of turbines interactions and waves.
Choose Your Own Marine Energy Adventure Game: Collision Risk
Authors: Hemery Lenaig , DeGuia Brandon , Pratt Martin , Tebbs Christiana , Cramer Nick , Garavelli Lysel
Published: September 2023

The risk of collision between marine animals (marine mammals, pelagic fish, and diving seabirds) and underwater turbines continues to be the first question raised by regulators for new tidal or riverine energy projects around the world, and the most significant issue that slows down consenting/permitting. The challenges to understanding collision risk stem from the difficulty in observing close encounters and interactions of marine animals with a tidal or riverine turbine, which rotates much slower than a hydroelectric turbine or a boat propeller. To better understand this risk, the marine energy community and the general public need to be educated on the processes and various stages involved in collision risk of marine animals with turbines. This project aimed to develop an interactive outreach tool for the marine energy community and the general public, to educate the audience on the low risk of collision by highlighting the different stages of a collision event at various spatial scales and featuring a fish species of concern, the Atlantic salmon. This tool is a three-dimension educational interactive experience, accessible from any web-connected platform, and is hosted on a publicly accessible website. Throughout the experience, the player is presented with various decisions to take as the salmon approaches and interacts with a tidal turbine. At each step along the way, the player is provided with bite-size scientific information and weblinks to deepen their understanding of the topic. This short but efficient tool with expert messages is a "hands-on" experience for the players, where they are the animals and make the decisions leading up, or not, to collisions. The outcomes of this project will support broad outreach and education goals in order to reduce barriers to consenting/permitting for future deployment of tidal and riverine turbines.
Measurements of tidal flow variability in Ramsey Sound, Pembrokeshire
Authors: Miles Jon , Coles Daniel , Simmonds David , Paine Alex , Barr Sue
Published: September 2023

The nature of the flow at in-stream tidal energy sites is particularly important for predicting array and device performance, and also for operations and maintenance planning.  Previous developers have reported issues such as the choice of vessel, cost of operations, and the limits of operation of deployment vessels. The dynamics of the flow around slack water has been of particular interest at Ramsey Sound in Pembrokeshire (UK) for planning the recovery of an existing turbine, the Tidal Energy Limited ‘Deltastream’.

This research presents flow characteristics of Ramsey Sound, based on analysis of Acoustic Doppler Current Profiler (ADCP) measurements and tide gauge data from the nearby Standard Port of Milford Haven.  The ADCP was located approximately 300 m across the channel, at the northern end of the channel, where the channel width was 1200 m and the mean depth was approximately 33 m. The flow dynamics were examined specifically to look at times potentially suitable for offshore operations Two weeks of data were used in the analysis, spanning a complete spring-neap cycle.

Results demonstrate that flow velocities exhibited clear asymmetry, with stronger flows on the northerly directed flood tide than on the ebb. There was considerable variation in the measured current speed around the time of the maximum, suggesting large scale bed feature generated turbulence. The flood (northerly) current maximum was approximately in phase with high water at Milford Haven. Cross correlation indicated that the flow generally led the elevation by 20 minutes.  In contrast to the expected theory, the current strength at mid-depth was stronger than at the surface on the maximum flood tide.  The maximum flow speed in the tide was reasonably predictable from the tide range at Milford. A threshold-based analysis of the ADCP measurements allowed the duration of slow-moving water to be identified for operation planning.

Operations and planning in light of sound understanding of hydrodynamics at tidal energy sites is critical for future economic success of the tidal energy sector. The results shown here from an ADCP deployment in Ramsey Sound have shown the capability to give useful tools for planning recovery operations.
Empowering Communities to Participate in Marine Energy Planning and Development
Authors: Chang Grace , Best Benjamin , Kramer Sharon
Published: September 2023

To meet community priorities and equitable outcomes, marine renewable energy (MRE) projects, such as those for marine energy and offshore wind, require informed and collaborative marine spatial planning (MSP) to overcome significant cultural, societal, and economic barriers that may limit responsible and accelerated deployment. Effective MSP brings together coastal communities and ocean users to coordinate decision-making for sustainable use of marine resources. The goal of this project is to develop digital tools to enable easy access to information, interactive visualization tools, and feedback mechanisms to empower communities to engage in meaningful communications with other stakeholders in the MSP process.

In collaboration with community organization partners, the Santa Barbara Maritime Museum and Redwood Community Action Agency, we held community-based workshops to solicit needs for communities to gain knowledge and communicate concerns about MRE development. The key results from initial outreach activities are:

The MRE planning process must incorporate stakeholder feedback starting in its early stages (as early as siting). Community benefits must be clearly articulated and quantified.

Communities generally distrust offshore energy developers. Communication with regulators and developers together would be useful.

Community members are eager to learn about MRE. Their biggest knowledge gaps are MRE device and array characteristics (size, extent, location) and effects of MRE development on the viewshed, recreational activities, and on wildlife.

There is too much information available over disparate sources. Community members do not know where or how to search for answers to questions about MRE development in their communities (or elsewhere).

Community members want to hit the ‘Easy Button’. Data need to be digestible and tools need to be easy to use with little technical knowledge or experience necessary.

Outreach activities guided the development of the following digital tools:

Interactive infographics to communicate topics of concern (e.g., viewshed impacts and potential interactions with whales) in a visually engaging and interative platform.

News feed relevant to MRE to quickly digest headlines and read articles in greater detail, sort articles by topic, and react to articles or other comments.

Artificial intelligence (AI) driven chat bot, which uses the latest in AI, namely GPT-3 (Generative Pre-trained Transformer 3), to produce real-time answers to user questions. Answers are logged, and can be reviewed and revised by marine energy experts to provide human vetting of the results.

Commenting system to provide feedback on information throughout the site, as well as the tools themselves.

These tools will empower communities with information and feedback mechanisms to promote meaningful stakeholder engagement and communications, and therefore, informed decision-making. These tools represent a major leap forward in ocean multi-use management with MRE.
Investigating the impact of multi-rotor structure shadowing on tidal stream turbine performance
Authors: Townley Bryn , Shi Weichao , Xiao Qing , Angeloudis Athanasios , Ashton Ian , Wray Bevan
Published: September 2023

As the tidal stream energy sector develops, reducing the Levelised Cost of Energy (LCOE) is essential to sustain commercialisation. Modular multi-rotor foundations, with bi-directional turbines, reduce offshore operational complexity through smaller turbine diameters and lift weight, in turn reducing the device Operational Expenditure (OpEx). With the introduction of modular, multi-rotor foundations, the wake-induced impacts that these structures have on turbine performance must be investigated to better estimate energy yield, loading, and fatigue life. This study sets the scene for investigating the relationship between the turbulent wake generated by a modular ballast weighted foundation and 2-bladed Horizontal Axis Tidal Turbine (HATT) motivated by the HydroWing multi-rotor device concept. The presented work aims to determine the broader magnitude and severity of the loads and establish a robust methodology to be followed with further high-fidelity modelling. Initially, a transient RANS Computational Fluid Dynamics (CFD) simulations environment with a sliding mesh is configured and validated against experimental data. A turbine in free-stream isolation is simulated as a benchmark case with the modular foundation sequentially introduced to analyse the impact of the structure. Key findings suggest that operating turbines downstream of the multi-rotor foundation could cause a 20% fluctuation in thrust loading at a 1.82 Hz frequency resulting in a mean Cp reduction of 8% over a revolution.
Tidal turbine wake characterization by vessel-mounted ADCP data analysis
Authors: Garcia Novo Patxi , Inubuse Masako , Terazaki Masakatsu , Matsuo Hiroshi , Archer Philip , Henzan Katsuhiro , Kyozuka Yusaku , Sakaguchi Daisaku
Published: September 2023

Wakes generated downstream turbines are one of the key points to be considered for tidal stream energy farm layout design. Distance between consecutive turbines must be optimized considering available resource spatial distribution and the current velocity reduction caused by upstream turbines. Tidal turbine wake characteristics have been analyzed experimentally and numerically, however, there is still a lack of studies presenting data measured in the wake of large-size turbines in tidal sites.

In this paper, the wake generated downstream of a SIMEC Atlantis Energy 0.5 MW turbine in Naru Strait (Nagasaki Prefecture, Japan) is analyzed using data measured with a vessel-mounted ADCP. This analysis is based on the comparison between data measured before turbine installation (September 2020) and during turbine operation (March 2021, May 2021, and September 2021). 

Due to the difficulties that measuring at the same position and the same tide moment with a vessel-mounted ADCP would mean, a direct comparison between these four datasets is unviable. To solve this issue, data were pretreated to calculate a ratio (RD) resulting from the division of current velocity values at every vertical layer by the current velocity measured at the shallowest layer. After that, this ratio is interpolated to a regular 3D mesh. Assuming that the current velocity profile shape for one point does not change with time, resulting RD values interpolated from data measured in different fieldworks can be compared.

The impact of tidal turbine operation on the current velocities is quantified with a variation ratio RV calculated by dividing RD during turbine operation (RD*) by RD before turbine installation (RD). These results show a clear velocity deficit even at 18D from the turbine, which clearly contrasts with results from other similar studies available in the literature, which may be related to the low turbulence intensity measured at the turbine installation point.
Validation of ERA5 Wave Energy Flux through Sailor diagram in Spain (2005-2014)
Authors: Saenz Jon , Carreno-Madinabeitia Sheila , Ibarra-Berastegi Gabriel , Ulazia Alain , Garro Mikel
Published: September 2023

The aim of this study is to validate the ERA5 Wave Energy Flux (WEF) estimations against observational data. To that end, 0.5° x 0.5° resolution ERA5 reanalisis WEF values and corresponding data from 15 directional REDEXT buoys of Puertos del Estado surrounding the Iberian and Canary Islands’ coast covering a period of ten years (2005-2014) have been used.

In this study, the Sailor diagram and its methodology [1] have been used to compare the skill of the model for a two-dimensional variable (WEF). The methodology on which the Sailor diagram is built proposes a diagram along with different statistical indices. In this particular case, WEF is a vectorial magnitude, and its zonal and meridional components (WEFx and WEFy) have been assessed at the same time.

To compare the observed data with the ERA5 data, well-known indices extended to two dimensions such as RMSE, correlation and bias have been used, as well as variances of each component. Furthermore, to analyse if the WEFx and WEFy components of the ERA5 data are rotated in relation to the observations, their relative rotation angle, eccentricity, and congruence coefficient of the first EOF (Empirical Orthogonal Function) have also been examinated. This way, the analysis is extended to fully cover the dimensionality of the data.

[1] Sáenz J, Carreno-Madinabeitia S, Esnaola G, González-Rojí SJ, Ibarra-Berastegi G, Ulazia A. The Sailor diagram – A new diagram for the verification of two-dimensional vector data from multiple models. Geosci Model Dev. 2020;13(7):3221–40. https://doi.org/10.5194/gmd-13-3221-2020