bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analisis Kerusakan Kepala Silinder Blok Mesin Pada Kendaraan Jenis Minibus Kapasitas 1500 CC
Authors: Zayadi Ahmad , Sungkono  , Masyhudi  
Published: September 2023

Abstrak,
Kendaraan roda empat merupakan salah satu moda transportasi yang umum digunakan pada era kini, pada umumnya kendaraan roda empat memiliki kepala silinder untuk menempatkan katup-katup dan tempat mantel pendingin. Apabila pada kepala silinder tersebut mengalami kerusakan maka akan mengakibatkan terganggunya sistem kerja mesin dalam jangka waktu yang panjang. Pada bagian mesin terdapat komponen kepala silinder apabila mengalami kerusakan maka akan membutuhkan waktu yang cukup lama untuk proses perbaikan. Dari informasi yang diperoleh bahwa kepala silinder mengalami kerusakan pada jarak tempuh 80.000 km. Kerusakan yang dialami kepala silinder adalah timbulnya suara kasar pada mesin, bercampurnya air pendingin ke ruang bakar dan temperatur suhu cepat naik, pada penelitian ini akan dilakukan kajian terhadap kerusakan yang terjadi pada kepala silinder tersebut. Berdasarkan hasil pengujian makrostruktur korosi terjadi akibat fluida pendingin mesin selain itu terdapat deposit yang melekat sangat kuat dan bersifat korosif kepala silinder pada blok mesin, pengujian mikrostruktur terlihat adanya endapan (hitam) yang diduga mempengaruhi proses korosi, butiran dendrit dan batang dalam mikrostruktur tidak mengalami perubahan ukuran butir. Berdasarkan pengujian kekerasan hasil menunjukan nilai kekerasan permukaan yang rusak sebesar 102,22 HV dan nilai kekerasan permukaan yang tidak rusak sebesar 102 HV berdasarkan tersebut kerusakan pada kepala silinder blok mesin tidak disebabkan oleh deformasi material akibat beban mekanik dan thermal. Hasil uji komposisi kimia kepala silinder yang mengalami kerusakan adanya penurunan Al 1,1%, Si 0,11%, Cu 0,37, Fe 0,088% dan Mg 0,081% dan adanya penurunan komposisi kimia unsur penyusun material tersebut diakibatkan oleh interaksi air dengan permukaan kepala silinder yang ditandai dengan terbentuknya oksida dari Al,Si,Cu,Fe, dan Mg. Berdasarkan hasil perngujian tersebut kerusakan kepala silinder lebih disebabkan karena kurangnya melakukan perawatan terhadap blok mesin agar komponen dapat bertahan lama sehingga kinerja dari mesin terjaga optimal.
ANNOTATING TRANSLATION AS A MEANINGFUL METACOGNITION-ORIENTED PRACTICE IN THE TRANSLATION CLASSROOM
Authors: Costa Cynthia Beatrice , Lourenço da Silva Igor Antônio 
Published: September 2023

Translating is a cognitively complex activity aimed at tackling an ill-defined problem: selecting only one viable rendition in the target language from a series of multiple viable choices for a given text in a source language (PYM, 2003). Developing the ability to perform such an activity with a reasonable speed and justified confidence (PYM, 2003) may profit from learning how to perform a parallel activity, i.e., annotating, as a fruitful avenue toward metacognition (ALVES, 2005; SHREVE, 2006) and the articulation thereof. We argue in this article that annotating (or commenting) can be an effective practice in the translation of any genre and play a relevant role from the beginning of translator’s training. Building both on a review of expertise (ERICSSON, 2001) and translation pedagogy (GONÇALVES, 2020; ESQUEDA, 2020) and on our own teaching experience, we suggest that annotating translation can: a) be performed as part of deliberate practice (in the broad sense) during the translation process, b) honestly inform students and trainers about the difficulties faced during the process, c) invite useful feedback, and d) potentially leverage students’ metacognition.
Numerical modelling of a box-type and bottom-detached oscillating water column wave energy conversion device: a comparison with experimental data and between BEM and CFD numerical modelling
Authors: Raghavan Vaibhav , Simonetti Irene , Lavidas George , Cappietti Lorenzo 
Published: September 2023

Utilization of Boundary Element Method (BEM) based on linear potential flow for modelling Oscillating Water Column (OWC) devices has gained popularity in the last two decades. The commercial BEM solver WAMIT has been used widely for modelling OWCs and validated using experimental modelling (Delauré et. al. 2003, Bingham et. al. 2015, Faÿ 2020). The open-source BEM solver NEMOH has however been mostly ineffective in modelling OWCs since the main approach adopted previously modelled the imaginary piston as a thin disk. In this research, the multi-body interaction problem has been adopted in modelling a box-type and bottom-detached OWC device in NEMOH, where the imaginary piston has been modelled to the length of the internal water column (Penalba et.al. 2017) and compared with experimental data. A further comparison is drawn with the numerical method of Computational Fluid Dynamics (CFD) , which has shown to be accurate for modelling OWC devices (Simonetti et. al. 2015), yet requires significantly higher computational resources than BEM. A two-dimensional CFD numerical wave tank, developed generating and absorbing waves with the waves2Foam toolbox (Jacobsen et al., 2012) of the open-source package OpenFOAM, is used for comparative purposes.
REFERENCES:
Delauré, Y. & Lewis, A. (2003). “3D hydrodynamic modelling of fixed oscillating water column wave power plant by a boundary element methods.” Ocean Engineering. 30. 309-330. 10.1016/S0029-8018(02)00032-X.
Bingham, H.B.; Ducasse, D.; Nielsen, K. et al (2015). “Hydrodynamic analysis of oscillating water column wave energy devices.” J. Ocean Eng. Mar. Energy 1, 405–419 (2015). https://doi.org/10.1007/s40722-015-0032-4
Faÿ F.-X. (2020). “Modelling and Control for the Oscillating Water Column in Wave Energy Conversion.” PhD Thesis, Universidad del País Vasco.
Jacobsen, N.G., Fuhrman, D.R. & Fredsøe, J., (2012). “A wave generation toolbox for the open-source CFD library : OpenFoam”. International Journal for numerical methods in fluids, 70, pp.1073–1088.
Simonetti, Irene & Cappietti, Lorenzo & Elsafti, Hisham & Oumeraci, Hocine. (2015). “Numerical Modelling of Fixed Oscillating Water Column Wave Energy Conversion Devices: Toward Geometry Hydraulic Optimization.” 10.1115/OMAE2015-42056.
Penalba, M., Kelly, T., Ringwood, J. 2017, NEMOH for Modelling Wave Energy Converters: A Comparative Study with WAMIT. 12th European Wave and Tidal Energy Conference , Cork, Ireland. https://www.researchgate.net/publication/319160625.
Internal waves
Authors: Raghukumar Kaustubha , Jones Craig , Chang Grace , Roberts Jesse 
Published: September 2023

Internal waves are ubiquitous oceanographic features that occur in various forms across the world’s oceans. They manifest themselves as interface waves across ocean density layers that represent the interplay between buoyancy and gravitational forces, and are typically classified as linear and nonlinear internal waves. Nonlinear internal waves are characterized by isopycnal displacements that can exceed 30 m, and current velocities that approach 1 m/s. Internal wave energy converters, if developed, could have the advantage of no surface expression and provide for the availability of renewable ocean energy in regions of scant surface wave energy resources.
Here, internal wave energies were computed at two locations: the New Jersey continental shelf and the coast of Central California. The available energy resource calculated for internal waves was then compared against surface gravity wave resources at each of these locations. Results suggest that the internal wave energy flux is comparable to that of surface waves on the New Jersey continental shelf during the summer of 2006 but is two orders of magnitude lower than that of surface waves in Central California during the summer of 2017. When expressed in terms of forces on a cylindrical structure, internal wave forces are an order of magnitude lower than that of surface waves on identically sized cylinders. However, the forces of the two resources are comparable when the diameter of the cylinder is doubled for the internal wave calculations. This suggests that while a larger energy converter would be required to harness internal wave energy, the larger size could be a reasonable tradeoff for advantages such as the lack of surface expression and the availability of energy in regions of limited surface wave energy resources.
These results could potentially pave the way for longer-time scale characterization of internal waves and the development of devices to harness this energy resource (thereby powering the Blue Economy), while augmenting the portfolio of marine renewable energy resources. Further, the dominance of internal wave energy resources during summer seasons when the water column is stratified can augment the surface wave energy resource that can be diminished during the summer season.
Investigation of Low Order Parameters Affecting Tidal Stream Energy Resource Assessments
Authors: Patel Misha , Smyth Amanda , Angeloudis Athanasios , Adcock Thomas 
Published: September 2023

Tidal stream energy may have the potential to contribute to the baseline energy needs of the UK. There is a significant difference between the existing assessments of the UK’s resource, highlighting the need for a standardised model. The paper investigates some challenges of quantifying tidal stream energy. This study examines the sensitivity of resource assessments to low-order parameters, in order to inform higher order modelling and contribute to defining a standardised model. A combination of channel characteristics, turbine parameters and simulation settings formed the basis of 96+ cases to determine key parameters affecting resource assessments. Two 0-dimensional, idealised channels were modelled using 2-8 constituents from four UK sites spanning the semi-diurnal form factor range. Blockage-corrected blade element momentum theory was used to represent variable-speed, variable-pitch turbines. Three blockage designed rotors and one rotor designed for an unspecified blockage were simulated. Power capping and combined power and thrust capping were implemented.

The study indicates dynamic balance is a key parameter affecting tidal dynamics when turbines are present in a channel. Variability of annual energy production due to the nodal cycle was most significant in the drag dominated channel with increasing blockage. Constituents with large amplitude and phase differences led to greater variability of the resource across the nodal cycle. Results indicate that the maximum deviation from the average annual energy production over the 18.6-year nodal cycle is +/- 8.8%. At a low form factor site, the difference between using 2 or 4 constituents was insignificant. However, for a higher form factor site, that is still semi-diurnal, the peak velocity increases by 0.32 m/s with 8 constituents compared to 2. Random Forest modelling indicates that the most important characteristic point on a variable-speed, variable-pitch turbine performance curve is the rated speed. Comparison of capping strategies highlights that combined power and thrust capping leads to an increase in energy per swept area. Combined capping decreased the variability of the resource over the nodal cycle, which is helpful to maintain a steady supply to the grid and sizing energy storage systems.
Multi-Actuator Full-Scale Fatigue Test of a Tidal Blade
Authors: Lopez Dubon Sergio , Vogel Christopher , Garcia Cava David , Cuthill Fergus , McCarthy Eddie , O Bradaigh Conchur 
Published: September 2023

Fatigue testing for tidal turbine blades involves the application of cyclic loads without matching the blade's natural frequency, which is challenging due to their high stiffness and associated thermal issues of composite materials at those frequencies (typically around 18Hz cycles). An auxiliary system is required to load the blades to address this challenge. However, traditional hydraulic systems tend to be highly energy-demanding and inefficient.
To solve this problem, researchers utilized real on-site data to define a series of equivalent target loads and implemented them in FastBlade, which proved an efficient way to perform fatigue testing. They used a regenerative digital displacement hydraulic pump system and achieved a remarkable 75% energy savings compared to a standard hydraulic system. During the testing, they utilized a system of 3 actuators instead of the traditional single actuator system, which produced more realistic and complex loads. We also address such changes in temperature along large composite structures during the test and mechanisms to address these issues.
Throughout the test, a series of measurements were taken on the blade response and FastBlade itself, which revealed exciting results on the mechanical behaviour of the blade and best testing practices for FastBlade. Impressively, the blade withstood 40 years' worth of accelerated fatigue loading without catastrophic failure.
Experimental passive and reactive control of a Laboratory Scale WEC Point Absorber
Authors: Bosma Bret , Beringer Courtney , Robertson Bryson 
Published: September 2023

Scaled testing is an important and valuable step in the process of determining best practices of WEC development, validating numerical models of WEC systems, and/or preparing for larger scale testing. Validation and verification of numerical models are very important as there are physical phenomena that are hard to numerically model such as non-linear frictional effects. This paper builds on the 2021 EWTEC paper [1] in performing and evaluating experimental testing of the Laboratory Upgrade Point Absorber (LUPA). Since this last paper, LUPA has been fabricated and deployed and an initial characterization has been performed. Particularly passive (damping), and reactive (damping and stiffness) control methodologies are employed in regular waves to characterize and evaluate the mechanical power extracted from the waves. Reactive control allows us to invest energyin the system to get a greater average energy out as compared to damping control.
The LUPA project has just finished its first deployment in the Large Wave Flume at the O.H. Hinsdale Wave Research Laboratory at Oregon State University as shown in Figure 1. Three modes of operation were tested, namely one body heave only, two body heave only, and six degrees of freedom. The one body heave only mode restricts the motion to linear and vertical and fixes the spar body so that the float is the only body free to move. The two body heave only maintains the vertical linear motion, but unlocks the float such that the float and spar are free to heave. The six degrees of freedom case is a floating moored mode with no restrictions on motion.
This paper will focus on comparing passive and reactive control for the one body heave only case and the six degreesof freedom case with preliminary results shown in Figure 2. Regular waves were tested, focusing on a single wave heightand sweeping the wave period. Results will be presented in power (W) units and in capture width (m). Fig. 2. Top shows max power output vs input wave period for one body and two body configurations and just damping and damping and stiffness cases.Take note of differing input wave height. Bottom shows capture width.
The LUPA project will provide a valuable testing platform for students and researchers. It will also provide a publicly available open source design and dataset for the research community here: https://github.com/PMECOSU/LUPA. This paper will serve as documentation of the initial testing of the system, providing baseline control results to be compared in future testing.
Numerical and experimental studies of the effects of WEC motion on a combined wind-wave energy platform
Authors: Koo WeonCheol , Kim Hong-Bhin 
Published: September 2023

The development of eco-friendly carbon-free marine energy is actively underway to alleviate the impact of global climate change due to excessive emission of carbon dioxide. To reduce the variability of energy production according to marine environment conditions and maximize energy production, the need for research on a suitable ocean energy platform is increasing. Therefore, various studies on motion control of ocean energy platforms are being conducted.
In this study, the motion response of a combined wind-wave energy platform equipped with multiple wave energy converters (WEC) capable of controlling the motion of a floating offshore wind turbine (FOWT) was numerically analysed and verified through a wave tank experiment. The combined energy platform with multiple WECs attached to the FOWT not only produces stable energy by controlling the motion response of the FOWT with the movement of the WEC, but also produces wave energy by the relative motion of the WEC.
The FOWT is a spar platform with taut moorings, and WEC is a moving cylinder hinged to the FOWT. The motion reduction effect of the FOWT by the movement of the WEC was investigated. Numerical analysis used the ANSYS AQWA program, which is a potential flow-based hydrodynamic program. To consider the restraining force of the FOWT due to the motion of the WEC, the multi-body dynamics theory was applied. The accuracy of the numerical model was improved by applying mooring dynamics, weakly nonlinear Froude-Krylov force, and nonlinear hydrostatic force. The experimental model was fabricated on a scale of 1/100 of the numerical model and was performed in a two-dimensional mini wave tank. To prevent the sidewall effect of the tank, the experiment was conducted only for the incident waves with various periods under the head sea conditions.
The numerical analysis results were in good agreement with the experimental results. In particular, the pitch of FOWT decreased significantly near the pitch resonance period because of the motion of WEC. The change in motion characteristics of the combined energy platform according to the movement of the WEC under various wave conditions was analysed.
comparative study of power production using a generic empirical model in a tidal farm
Authors: Shariff Kabir Bashir , Guillou Sylvain 
Published: September 2023

This study presents a generic model for estimating the velocity deficit and turbulence intensity ina tidal turbine farm. The proposed model considers a range of ambient turbulence intensity, the rotor diameter-to-depth ratio, and the rotor thrust coefficient in realistic applications. We evaluate the power generation of a large-scale tidal farm composed of 16 turbines in an in-line and staggered configuration in an ideal channel similar to the Alderney Race in the English Channel. The added turbulence effect is taken into account when assessing the velocity deficit in the farm. As supported by previous studies, the results show that the staggered array produces more power than the rectilinear array. The staggered arrangement benefits from flow acceleration and wide turbine spacing, which improves wake recovery. According to the results, the farm can be resized by decreasing the lateral spacing in the rectilinear array and decreasing the longitudinal spacing in the staggered array without affecting the farm’s efficiency. The reduction in farm size will reduce cable costs and provide an opportunity for future expansion. For the tidal turbines in shallow water regions, the ratio of rotor diameter to depth is shown to affect the power generated by the turbines. The power produced in the farm decreases with an increase in the rotor diameter-to-depth ratio due to the limited wake expansion along the vertical plane. This low-computational model can be useful in studying the wake interaction of tidal turbine parks in different configurations.
Numerical optimisation of the active lift turbines using OpenFoam's overset method
Authors: Robin Ilan , Mouazé Dominique , Bennis Anne-Claire , Carpentier Guillaume 
Published: September 2023

This work presents a preliminary study of the numerical optimization of "active lift turbine" using computational fluid dynamics (CFD). This active lift turbine is designed to improve efficiency of vertical axis energy recovery turbines (wind and tidal turbines). It uses a crank rod system to convert normal forces into momentum in order to improve the yield.
After a validation work of CFD model in two dimensions, the numerical optimization of the tidal turbine system is carried out. In fact, due to the specific characteristics of the active lift turbine, the blades do not follow a circular trajectory (Fig. \ref{fig:combined}). The OpenFoam overset module is therefore chosen because it allows to control the motion of the blades easily \cite{Chalmers}. The Overset method allows a good performance evaluation and limits the risk of numerical divergence that could be caused by mesh deformation methods; Moreover it limits the computation time compared to remeshing methods. However, it is more expensive than a more traditional Arbitrary Mesh Interface method \cite{Openfoam}, which is not suitable for the active lift turbine simulations.
The impact of several parameters on the performances is studied. The simulations are performed for a range of operating conditions including different inflow velocities, angles of attack and active flow turbine settings (like the amplitude of the radius variation, see Fig \ref{fig:combined}). The results are evaluated in terms of the turbine power output and efficiency.
The results show the importance of numerical simulation for the development of new types of energy recovery systems. It allows a better understanding of the interactions between the turbine and the fluid, and of the operation of such systems.
Further studies are required for the active lift turbine: conventional attempts at optimisation are not perfectly suited to this system. Improving the lift/drag ratio makes less sense when the normal forces should also be taken into account to improves the performances. Furthermore, other aspects of operation should be analysed: variation of the turbulence rate, implementation of boundary layer re-attachment systems...