bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving data sharing in practice – power curve benchmarking case study
Authors: Barber Sarah , Ding Yu
Published: May 2024

In this work, a data sharing case study is presented, aiming to investigate and demonstrate how data sharing can be improved in practice in the wind energy sector. The case study is part of the WeDoWind framework, which creates tangible incentives to motivate different types of people to actually share data in practice. For this, a WeDoWind “challenge” on the topic of wind turbine power curve benchmarking is created and implemented within the framework. The results allow five different data-driven power curve prediction methods to be compared. The best method reduces the model error by as much as 70% in terms of mean absolute error and 45% in terms of root mean squared error compared to the standard industry method of binning. The results of a survey filled out by the participants show that data sharing could be improved compared to previous WeDoWind case studies, by providing more clear comparison and evaluation criteria, as well as by better integrating students into the WeDoWind framework. Overall, we find that “challenge”-based collaborations can help the industry become more innovative, by providing a motivation and basis for sharing data, as well as for comparing and benchmarking different methods. Finally, our experience in doing this as part of the present work allows us to make some suggestions for improving data sharing in practice.
Challenges on prognostics and health management for wind turbine components
Authors: Cuesta Jokin , Leturiondo Urko , Vidal Yolanda , Pozo Francesc
Published: May 2024

This paper explores the applicability of prognostics and health management (PHM) for wind turbines (WTs), presenting the PHM approach along with challenges and opportunities in the context of WT components. First, the PHM framework is introduced, consisting of three blocks: observation, analysis, and action. Critical components and failure modes for WTs are identified, and data acquisition strategies using supervisory control and data adquisition (SCADA) and condition monitoring (CM) data are discussed. Prognostics, specifically remaining useful life (RUL) estimation, employs physics model-based, data-driven, and hybrid models. Finally, challenges and opportunities related to data, analysis and CM, and developing RUL prediction models have been found. Data challenges include data standardization, limited public datasets, and data quality issues. Analysis and CM challenges address new sensorless and non-intrusive techniques, as well as the fusion of data sources. Prognostics model challenges involve uncertainty management, interpretability issues, and the need for online updates. Addressing challenges requires incorporating physical knowledge, utilizing transfer learning, and improving online RUL prediction methods.
Offshore field experimentation for novel hybrid condition monitoring approaches
Authors: Kestel Kayacan , Jamil Faras , Jo Matthys Jens , Vratsinis Konstantinos , Sterckx Jonathan , Marini Rebeca , Peeters Cédric , Helsen Jan
Published: May 2024

This study details the development of a fully automated pipeline for the condition monitoring of wind turbine drive trains. Vibration data is collected using hardware designed and manufactured in-house and used directly to monitor the condition of the drive trains. The complex nature of wind turbine vibration signals, due to the large number of components and highly variable operating conditions, makes drive train condition monitoring a challenging task. This paper details the full data measurement and analysis flow from sensor to insights and proposes a hybrid automated pipeline with signal processing and data-driven techniques to address the complexity of dealing with wind turbine vibration data. The vibration signals are directly employed to estimate the wind turbine’s instantaneous angular speed to compensate for any rotation speed fluctuations. Pre-processing is performed on the speed-independent signals to evaluate condition indicators in both the time and spectral domain for the vibration signals and their envelopes. Machine learning is then employed to distinguish the healthy state of the machine from a faulty one using the computed condition indicators. Besides the scalar indicators, also two-dimensional vibration decompositions such as the cyclic spectral correlation maps are used as inputs to the machine learning pipeline. This comprehensive and automated approach ensures both an early and reliable fault detection. Experimental results demonstrate that the fully automated hybrid pipeline can effectively be used for fleet-based health tracking of offshore wind turbine drivetrains.
Development and verification of a discrete event simulation tool for high-fidelity modelling of offshore wind and solar farm decommissioning campaigns
Authors: Mancini Simone , Bloothoofd Jesse , Dighe Vinit , van der Mijle Meijer Harald
Published: May 2024

The number of offshore wind turbines to be decommissioned is expected to grow in the next decade but some of the oldest wind farms in the North Sea region are already approaching the end of their service lives. This means that several detailed decommissioning plans will need to be prepared in the coming 2-5 years. So far, only small-scale wind farms consisting of relatively small turbines located in shallow, near-shore, or confined waters have been decommissioned. The limited experience and data available yield high uncertainty in the estimation of costs, duration, and environmental footprint of upcoming offshore wind farm decommissioning campaigns. High-fidelity logistic simulation tools as well as high-level cost models are both needed to support end-of-life decision-making. While several holistic cost models have been proposed, the literature lacks high-fidelity models to support the detailed planning and execution of offshore wind farm decommissioning projects. Given that offshore operations are the greatest source of costs, emissions, and safety risks in decommissioning campaigns, these require special attention when seeking optimization opportunities. In this work, a high-fidelity logistic simulation module for the decommissioning of offshore wind and solar farms has been developed within the discrete event simulation platform UWiSE. The new UWiSE Decommission module enables detailed assessment of alternative decommissioning scenarios taking into account offshore operation complexities like weather and resource dependencies, which are not included or heavily approximated in holistic cost models. The new tool has been verified against publicly available analytical cost model results from recent literature. A short assessment of the impact of weather delays on cost and duration estimates for the considered offshore wind farm decommissioning campaign has also been performed as an example of how UWiSE Decommission may bring value to the planning of offshore decommissioning projects.
Full scale testing of fatigue resistant composite joints for offshore wind Jacket and Floating structures
Authors: Pavlovic M , Koetsier M , Yang J , Mylonopoulos V , Wolters M , Segeren M , Van Wittenberghe J , Thibaux P , Vanderschueren M
Published: May 2024

Complex welds in the joint region reduce the fatigue resistance of structural joints of circular hollow sections with factors that results in increased wall thicknesses of the tubes and overspending of steel in the multi-membered part of the jacket and floating support structures for offshore wind turbines. The wrapped composite joint is a breakthrough technology utilising bonding and fatigue resistant composite material to connect steel tubular members instead of welding. The main technical advantage is that the superior fatigue life of wrapped composite joints. Full-scale wrapped composite joint is tested by cyclic out-of-plane bending loading in resonance-based Cronos testing rig at OCAS N.V. in Belgium. Results reveal exceptional fatigue life of wrapped joints to combined loading when compared to welded joints, showcasing a potential that can radically reduce steel use for offshore structures.
Incorporating Electricity Prices in Wind Turbine Design: Introducing the AEV Metric
Authors: Bechmann A , Barlas T , Madsen H A
Published: May 2024

This paper addresses the challenge of incorporating electricity prices into wind turbine design methods and shows how price volatility drives wind turbines towards larger rotors and lower specific power. Since wind speed and electricity prices fluctuate, current efforts to estimate a wind turbine’s revenue are based on time-series approaches. However, this paper presents a new way of accounting for price volatility based on wind distributions, which is computationally cheap and easily integrates with current wind turbine and farm design methods and tools. The new method demonstrates that a traditional wind turbine can lose more than 15% of its revenue in open energy markets like Denmark due to price volatility. Designing turbines with lower specific power can substantially increase revenue by producing more energy at low wind speeds with higher energy demand and electricity prices.
Methodology to assess scour development around complex structures
Authors: Sarmiento J. , Fernández S. , Guanche R.
Published: May 2024

Accurate prediction of scour evolution around fixed offshore foundations is a key parameter for selecting the most appropriate scour mitigation strategy. Various formulations can be used to estimate scour around monopiles. However, non-specific formulations have been developed for more complex foundations. In the case of jacketed offshore substations (OSS), the geometry can be one of the most complex. This paper describes a hybrid methodology (numerical model simulations, semi-empirical approaches and physical experiments) to estimate the scour evolution around OSS. The application of this methodology allows the selection of the most appropriate mitigation strategy from an early stage of the project to the final decision. The methodology is accompanied by some examples. In general, the results obtained from the semi-empirical approaches show quite good agreement with the measurements from the physical experiments. Nevertheless, considering the complex geometry of the OSS and the potential non-linearities associated with the platform geometry, physical experiments are required to ensure the correct estimation of the maximum scour (local and global).
Designing Large Segmented Flexible Conical Plain Bearings as Wind Turbine Main Bearings
Authors: Jakobs T , Jacobs G , Rolink A , Euler J , Hollas C , Röder J
Published: May 2024

Main bearings are failure-prone components in wind turbines, significantly increasing the LCOE of wind energy. Therefore, segmented plain bearings are being discussed as replacement for the currently used rolling bearings. Segmented plain bearings allow an up-tower replacement of faulty segments without the need to dismantle the WT drivetrain, as is required for rolling bearing replacements. One such bearing is the segmented, flexible, conical “FlexPad” plain bearing as alternative to existing double row tapered roller bearings. Designing the FlexPad bearing manually is very complex and thus time-consuming. Hence, during the research project a new holistic design method for large and highly loaded, conical plain bearings was developed. To prove the suitability of the method, two bearing prototypes were built and tested. The prototype, designed with the new method, outperformed the first, manually designed bearing, in terms of the design objectives. Most importantly, the friction losses were reduced by 32.1%. The project results show that the new method is able to efficiently design safely operating FlexPad bearing variants for wind turbines.
Phase-field simulation of the effect of grain boundary on fission gas migration in UO2 fuel
Authors: Liu Dongkun , Wang Qingyu , Zhang Tian
Published: May 2024

Grain boundaries are widely recognized as line defect sinks. During reactor operation, vacancies and fission gas atoms within UO2 fuel grains migrate to the grain boundaries, forming bubbles at these locations. In order to better understand the effect of grain boundaries on the migration of fission gas atoms, this study employed a phase-field model to simulate the nucleation and growth process of fission gas bubbles within the UO2 fuel grains and in the vicinity of grain boundaries. This study also investigated the degree to which grain boundaries affect fission gas atoms under different temperature conditions. The results indicated that in models containing grain boundaries, the nucleation of fission gas bubbles occurred earlier, as compared to models without grain boundaries. A noticeable bubble denuded zone was also observed adjacent to grain boundary interfaces. Furthermore, with increasing temperature, the bubble denuded zone becomes thicker. The effects of irradiation, vacancy diffusion, Ostwald ripening, as well as grain boundary trapping were discussed.
Molecular dynamics simulation of thermal properties of modified graphene / n-octadecane composite phase change material
Authors: Li J , Mao Y , Yang X , Liao Y N , Cai D , Chen S S , Sun K , Zheng Y J
Published: May 2024

Phase change materials have been widely used in building energy-saving and off-peak energy storage systems, but most phase change materials limit their application because of their low thermal conductivity. Improving their heat transfer performance and revealing the heat transfer mechanism from a microscopic perspective are the keys to practical applications. The PCM system composed of n-octadecane and modified graphene was established by molecular dynamics simulation and the influence of macro thermal properties was analyzed from a microscopic perspective including end-to-end distance and torsional angle distribution, radial distribution function, and self-diffusion coefficient. The results show that the thermal conductivity of PCMS increases with increased modified graphene content. When the mass fraction is 26.88%, the thermal conductivity increases by 44.5%, which is consistent with the trend of experimental values. The addition of modified graphene resulted in a more concentrated distribution of n-octadecane molecules, indicating that the arrangement of n-octadecane molecules was affected, increasing the thermal conductivity of n-octadecane. The deviation of phase transition temperature from the experimental value is less than 1%.
Direct formation of nano-scale dislocation loops during displacement cascade in BCC Fe studied by molecular dynamics simulation
Authors: Cao Han , He Xinfu , Wu Shi , Wang Dongjie , Jia Lixia , Dou Yankun , Yang Wen
Published: May 2024

In this work, the displacement cascades in bcc iron were simulated by molecular dynamics (MD). The formation of dislocation loops was found in cascade simulations when the energy of PKA (EPKA) was above 20 keV. For the first time, we reported the formation of <100> interstitial dislocation loops in cascade simulation of bcc iron under low EPKA, about 40 keV, much lower than that in Ref. 10. On the other hand, our results suggest that <100> loops all transformed into 1/2<111> loops within 200 ps. This will help us build a microscopic image and mechanism about the formation of interstitial dislocation loop.
Transient growth of wavelet-based resolvent modes in the buffer layer of wall-bounded turbulence
Authors: Ballouz Eric , Dawson Scott T. M. , Jane Bae H.
Published: May 2024

In this work, we study the transient growth of the principal resolvent modes in the minimal flow unit using a reformulation of resolvent analysis in a time-localized wavelet basis. We target the most energetic spatial wavenumbers for the minimal flow unit and obtain modes that are constant in the streamwise direction and once-periodic in the spanwise direction. The forcing modes are in the shape of streamwise rolls, though pulse-like in time, and the response modes are in the form of transiently growing streaks. We inject the principal transient forcing mode at different intensities into a simulation of the minimal flow unit and compare the resulting nonlinear response to the linear one. The peak energy amplification scales quadratically with the intensity of the injected mode, and this peak occurs roughly at the same time for all forcing intensities. However, the larger energy amplification intensifies the magnitude of the nonlinear terms, which play an important role in damping the energy growth and accelerating energy decay of the principal resolvent mode. We also observe that the damping effect of the nonlinearities is less prominent close to the wall. Finally, we find that the principal resolvent forcing mode is more effective than other structures at amplifying the streak energy in the turbulent minimal-flow unit. In addition to lending support to the claim that linear mechanisms are important to near-wall turbulence, this work identifies time scales for the nonlinear breakdown of linearly-generated streaks.
Turbulent activity in the near-wall region of adverse pressure gradient turbulent boundary layers
Authors: Gungor Taygun R , Maciel Yvan , Gungor Ayse G
Published: May 2024

Two direct numerical simulation (DNS) databases are investigated to understand the effect of the outer-layer turbulence on the inner layer’s structures and energy transfer mechanisms. The first DNS database is the non-equilibrium adverse-pressure-gradient (APG) turbulence boundary layer (TBL) of Gungor et al. [1]. Its Reynolds number and the inner-layer pressure gradient parameter reach above 8000 and 10, respectively. The shape factor spans between 1.4 and 3.3, which indicates the flow has various velocity defect situations. The second database is the same flow as the first one but the outer layer turbulence is artificially eliminated in this flow. Turbulence is removed above 0.15 local boundary layer thickness. For the analysis, we chose four streamwise positions with small, moderate, large, and very-large velocity defect. We compare the wall-normal distribution of Reynolds stresses, two-point correlations and spectral distributions of energy, production and pressure strain. The results show that the inner layer turbulence can sustain itself when the outer-layer turbulence does not exist regardless of the velocity defect or the pressure gradient. The two-point correlations of both cases show that outer large-scale structures affect the inner layer structures significantly. The streamwise extent of the correlation contours scales with pressure-viscous units. This shows the importance of the pressure gradient’s effect on the inner-layer structures. The spectral distributions demonstrate that the energy transfer mechanisms are probably the same in the inner layer regardless of the velocity defect, which suggests the near-wall cycle may exist even in very-large defect APG TBLs where the mean shear in the inner layer is considerably lower than small-defect APG TBLs.
Coherence analysis of geophysical wakes in flow past a three-dimensional hill
Authors: Liu Jinyuan , Sarkar Sutanu
Published: May 2024

Wakes generated by topographies are ubiquitous in nature. The formation and evolution mechanism of wake-generated eddies is essential to understanding the effect of topography on oceanic bottom flow. In this study, we analyze the temporally resolved numerical database [1] of stratified wakes past an isolated three-dimensional hill, via proper orthogonal decomposition (POD) of the vertical vorticity field. We study the dynamics of the near wake (x/D < 3) and the far wake (x/D ≥ 3) separately, where x is the downstream distance from the center of the hill. The aim is to understand how rotation influences the change of coherence from the near to the far wake and also the coherence across heights.
Energy transfer in the formation and evolution of energy-containing motions in turbulent boundary layers
Authors: Matas Antonio , Liu Kevin , Kannadasan Ezhilsabareesh , Atkinson Callum , Soria Julio
Published: May 2024

This paper examines using direct numerical simulation (DNS) the recovery of the energy-containing scales of motion (energy-containing motions) when these are removed at the inflow boundary condition of a flat plate zero-pressure gradient turbulent boundary layer (ZPG-TBL). The energy-containing motions are identified from the spanwise spectral energy density of the interscale turbulent transport. Analysis of the resulting spanwise spectral energy densitiy of velocity and vorticity suggests that near-wall streaks are the initial energy-containing motions formed with quasi-streamwise vortices only developing further downstream. This result is in agreement with the previous study on turbulent channel flows by Kannadasan et al. [1].
Temporal vortex tracking in isotropic turbulence
Authors: Ghira Afonso A. , Vela-Martin Alberto , Da Silva Carlos B.
Published: May 2024

An algorithm to allow the temporal vortex tracking of the intense vorticity structures is introduced and applied to direct numerical simulations (DNS) of homogeneous isotropic turbulence (HIT). The algorithm allows the identification of the individual life events of the worms, including events of splits into several structures and of merging between different structures. Results obtained from a relatively small DNS, with Taylor based Reynolds number equal to Reλ
= 54, for a simulation lasting more than 6 integral time scales, shows that the complement of the CDF of the life time of the IVS is well approximated by an exponential distribution function. The mean life time of the IVS which is approximately 3.6τη
, where τη
is the Kolmogorov time, and the birth rate of these structures is close to 4.5/τη
(number of new structures per Kolmogorov time). A population model is built to predict the number of existing structures at any time, which gives a number of existing IVS equal to ≈ 16, which agrees well with the results from the DNS.
Coherent structure tracking of the second Mack mode in transitional hypersonic boundary layers
Authors: Hammachi Riwan , Piot Estelle , Deniau Hugues , Brazier Jean-Philippe , Daviller Guillaume , Cardesa José I.
Published: May 2024

The natural transition of hypersonic boundary layers (HBLs) is often expressed in terms of discrete modes and their linear stability. A frequent interpretation revolves around fast and slow acoustic modes interacting in the vicinity of the vortical/entropic branches of the continuous spectrum found from stability analyses. Yet several transition scenarios are contingent upon factors such as the spectral content of the free-stream disturbances, or the interactions between the discrete modes within the boundary layer and the free-stream disturbances near the leading edge which can be decomposed into vortical, acoustic and entropic nature based on the fluid-thermodynamic (FT) components. Yet the interpretations of linear stability applied to discrete modes can lead to semantic conflicts with the terminology of FT components. To clarify the current description of the processes involved, this study chooses an approach aimed at characterizing the dynamics of the second Mack mode in transitional HBLs through coherent structure tracking. The method involves decomposing the flow perturbations into acoustic, vortical and entropic content, and following their associated coherent structures over time. For this purpose, direct numerical simulations are carried out to investigate the dynamics of the second Mack mode instability in two-dimensional HBLs, considering a flow at Mach 6 over a cooled and an insulated wall. It is found that vortical structures coexist at different heights along the wall surface, forming alternating sign doublets around the critical layer and above the relative sonic line. These structures are found to merge in the region of maximum second Mack mode instability.
Causality between streaks and bursts in wall-bounded turbulence
Authors: Ling Yuenong , Lozano-Durán Adrian
Published: May 2024

We use an information-theoretic method, referred to as information flux, to quantify the causal relationships between streaks and bursts in a non-intrusive manner. Within this framework, causality is quantified as the flux of Shannon information from the present of the quantities of interest to their future. We also use the so-called information leak to measure the information that is not accounted for due to unobserved variables. We investigate data from a direct numerical simulation of turbulent channel flow at the friction Reynolds number Re

τ

≈ 180. The spatial distribution of causality is investigated as two time scales based on 50% value of the information leak and maximum of the normalized cross-induced information flux. It is found that the most causal spatial configuration for streaks and bursts is always streamwise-aligned. Furthermore, four dominant causal spatial configurations between streaks and bursts are identified. At the short time scale around 10 viscous units (when information flux is 50%), streaks and bursts have comparable causality to one another. At the longer time scale (corresponding to the maximum cross-induced causality), there is greater causality from streaks to bursts.
Inter-scale Causality Relations in Wall Turbulence
Authors: De Salis Young J , Hao Z , Garcia-Mayoral R
Published: May 2024

We investigate the inter-scale energy transfer in the buffer layer between different streamwise and spanwise lengthscales. In a periodic channel, inter-scale transfer of momentum in the periodic directions is only possible through wavenumber interactions in the non-linear advection term. The aim of this study is to map the inter-scale interactions which transfer energy through advection to different lengthscales of interest. The non-linear advection term has nine contributions, which correspond to three different advecting and advected velocity components. Because the flow is anisotropic, each of these contributions can be viewed as portraying a different physical mechanism. Maps of inter-scale transfer are therefore constructed for each of the nine contributions to the advection term in order to understand the relative importance of advecting and advected velocity components in wall turbulence. As a preliminary exploration, two maps of the inter-scale energy transfer in the buffer layer are presented for Reτ
= 180, one for transfer to a ‘target’ lengthscale dynamically relevant in the near-wall cycle,

λ

x

+

=
188

,

λ

z

+

=
94

and one for transfer to a ‘target’ lengthscale in the dissipative range,

λ

x

+

=
42

,

λ

z

+

=
21

. In the first case, we observe that the transfer of energy is dominated by transfer into streamwise-velocity (u) by spanwise-elongated structures of spanwise-velocity (w) that advect streamwise-elongated structures of streamwise-velocity (u). This is nothing but the process of streak meandering induced by spanwise-elongated (w) structures. In the second case, the inter-scale transfer can be split into three dominant mechanisms. The first and second mechanisms are observed across many of the nine contributions to the advection term. Velocity structures with size similar or larger than streamwise streaks either advect (mechanism 1) or are advected by (mechanism 2) velocity structures with lengthscales close to the target one. The third mechanism is only significant for streamwise (u) velocity structures advecting streamwise (u) and spanwise (w) velocity, and involves structures with an intermediate scale which is in-between the dissipation scale and the near-wall cycle dynamic lengthscale, but still in the dissipation range. In this mechanism, intermediate-scale streamwise-velocity structures advect intermediate-scale streamwise- and spanwise-velocity structures.
Adaptivity of a leaf-inspired wind energy harvester with respect to wind speed and direction
Authors: Sabzpoushan Seyedali , Woias Peter
Published: May 2024

Environmental wind is a random phenomenon in both speed and direction, though it can be forecasted to some extent. An example of that is a gust which is an abrupt, but short-time change in wind speed and direction. Being a free and clean source for small-scale energy scavenging, attraction of wind is rapidly growing in the world of energy harvesters. In this paper, a leaf-like flapping wind energy harvester is introduced as the base structure in which a short-span airfoil is attached to the free end of a double-deck cantilever beam. A flap mechanism inspired by scales on sharks’ skin and a tail mechanism inspired by birds’ horizontal tail are proposed for integration to the base harvester to make it adaptive with respect to wind speed and direction, respectively. The use of the flap mechanism increases the leaf flapping frequency by +2.1 to +11.5 Hz at wind speeds of 1.5 to 6.0 m s−1. Therefore, since the output power of a vibrational harvester is a function of vibration frequency, a figure of merit or an efficiency parameter related to the output power will increase, as well. On the other hand, if there is a misalignment between the harvester’s heading and wind direction due to change of the latter one, the harvesting performance deteriorates. Although the base harvester can realign in certain ranges of sideslip angle at each wind speed, when the tail mechanism is integrated into that, it broadens the range of realignable sideslip angles at all the investigated wind speeds by up to 80

∘

.
Adaptation, Mitigation and Resilience: Learning from the Coastal and Surrounding Communities Forest
Authors: Sylviani  , Sakuntaladewi N
Published: May 2024

Climate change can affect seasonal patterns in a region and result in extreme weather conditions, thereby significantly impacting the lives of communities, especially those heavily dependent on the surrounding ecosystems such as fishermen and forest-dwelling farmers. They must continually adapt to the seasonal patterns and extreme weather to ensure their survival. This article discusses the impacts of seasonal changes, adaptation strategies, and community vulnerability, particularly among those residing in coastal areas and near forests. The method employed involves evaluating several research findings and reviews summarized in a discussion. The study’s findings indicate that climate change prompts communities to take reactive and anticipatory actions. Coastal communities, especially fishermen, adapt to seasonal changes by adjusting fishing schedules and modifying fishing equipment, improving embankments, tertiary water channels, culverts for water gate enhancements, and planting mangroves on embankments to reinforce them and along the coast to protect their fishponds. Communities reliant on forests adapt to seasonal changes by adjusting planting times and crop varieties to align with local seasonal characteristics. This adaptive ability ensures their access to food supplies and resilience against climate change. The implications of adaptation to seasonal changes can change the lifestyle of coastal communities and those around forests.
Semendo Coffee Development and Partnership Strategy to Enhance Governance for Food Security and Climate Change Mitigation
Authors: Hanapi S , Malau L R E , Laksono P , Alfayanti  , Ulya N A , Hutapea Y , Damayanti E C , Fitriani Y , Anita Y , Saisan D G M
Published: May 2024

Semendo coffee is a major income source for agricultural households in the Semendo region. Agroforestry is commonly employed practice at numerous Semendo coffee plantations. Timber and Multipurpose Tree Species widely cultivated to provide shade. This study examines Semendo coffee’s governance-enhancing development and collaboration methods. SWOT (strength, weakness, opportunities, threats) and AHP (analytic hierarchy process) analysis are used to determine the most suitable governance strategies and policies for Semendo coffee development. The data was gathered from key persons who possess expertise and serve as representatives for pertinent stakeholders and commercial entities throughout the Semendo coffee supply chain. SWOT analysis shows that the Strength-Opportunity (SO) strategy could improve Semendo coffee governance. High-quality coffee production, relevant party cooperation, and marketing network expansion are the proposed strategies. The AHP says mutual need drives partnership decision-making the most. Plasma-core partnerships are best for creating a strong sense of mutual need. Integration of the SO strategy with the core-plasma partnership is proposed to improve Semendo coffee governance. Agroforestry in Semendo coffee production can produce fruits and sequester carbon, reducing climate change. Agroforestry-based Semendo coffee management is expected to improve food supply, distribution, and consumption. This development is expected to maintain environmental integrity, notably in climate change mitigation.
Optimizing the role of rice central market in Java, Indonesia: the effect of toll roads construction to the rice market integration
Authors: Dharmawan Budi , Dumasari  , Nasir Muh Amat , Aisyah Dinda Dewi
Published: May 2024

Rice is considered as the primary staple food that Indonesian people mostly consume on daily basis. The need of rice in Indonesia is always increasing. However, the production of rice in Indonesia has not meet its demand. One of the factors resulting the number of paddy field decreasing is the construction of toll roads. The government of Indonesia has invested intensely in the development of a toll road network. The length of toll road operation has increased from around 750 km in 2014 to over 2,500 km in 2022. The construction encroaching paddy fields and resulting the production of rice decreasing every year. The paper objective is to investigate the implications of toll road investment to the rice market integration by focusing on Java as the central rice-producing region in Indonesia. We used the Vector Error Correction Model (VECM) approach to analyze the long-ranging daily rice price data series. The result of the study found that Cipinang Central Market in Jakarta has not the significant spatial market integration with rice markets in Java. Despite the fact that West Java, East Java, and Central Java with Cipinang Central Market have a major business tie, prices are not increasing. This shows a severe lack of market integration. The phrase “optimal market integration” refers to a more efficient market, especially when it comes to establishing rice market prices.
The estimation of above-ground oil palm carbon stocks of different ages through vegetation index
Authors: Prastowo Erwin , Andari Masyitah Tri , Hakim Arif Rakhman
Published: May 2024

Above-ground carbon stocks play an important role to support the sustainability of oil palm plantation, and vary with soil characteristics, climate conditions, and agronomic practices. The common direct approach to assess aboveground carbon stocks may be time-consuming, and laborious, so may not be suitable especially for large scale observation. Therefore, the use of remote sensing may overcome some limitations coming up for conventional methods, yet requires a considerable data validation to obtain a reliable model. In this study, the normalized difference vegetation index (NDVI) based on Sentinel-2 satellite imagery, acquired in September 2023, was used in combination with field measurements, i.e. biomass estimation, investigated in three separated of oil palm plantations differing in ages, i.e. young (< 10 years), middle (10 – 20 years) and old (> 20 years), subjected with similar soil characteristics, and climate condition, in Bojong Datar, Cibungur, and Cikasungka, West Java. Results show that above-ground carbon stocks increase with oil palm ages, i.e. from young to middle ages, with value ranging from 3.40 – 65.70 ton/ha, yet decreases down to 17 ton/ha with ages > 20 years. Similarly, it also occurred for NDVI index, i.e. increase from 0.50 – 0.59 for young to middle of oil palms, and down to 0.51 for oil palm > 20 years old. This study suggests a strong correlation between carbon stocks and NDVI values (R2 = 0.878), pointing out the potential use of vegetation index to estimate above-ground oil palm carbon stocks. In the future, with further validation, the use of NDVI to estimate plant biomass may provide a potential substitute for the field measurement methods with a considerable higher efficiency and accuracy.
Research on the production technology of rubber epoxy from concentrated natural rubber latex
Authors: Trinh V D , Luu T H , Nguyen T Q
Published: May 2024

The results of research on epoxidation technology from concentrated natural rubber latex (CNRL) and in-situ peroxyformic acid, which is synthesised from formic acid (FA) and hydrogen peroxide (HP), are presented in the article. The study investigated the influence of technological parameters of the epoxidation process, such as stabiliser content (nonylphenol ethoxylate, NP9), dry rubber content (DRC), isoprene, stirring speed, reaction time, reaction temperature, and molar ratios of hydrogen peroxide and isoprene (IP), on the epoxy resin content of the product. Research results have shown that the epoxidation reaction with NP9 at 10% takes from 2.5 to 20 hours under the following conditions: latex composition contains from 16 to 24% DRC, stirring speed 100 rpm, reaction temperature response 30 to 70 °C, HP/IP molar ratio changes from 0.7 to 1.3, FA/IP ratio is 0.2, the product was stable and without coagulation. The product was obtained with an epoxy content of 23.4 to 43.6%. This is the basis for building an epoxidized natural rubber (ENR) production process to create a series of natural rubber products that are renewable, environmentally friendly, low-cost, and have many industrial applications.
A novel La2MnTiO6 perovskite for photocatalytic degradation of tetracycline hydrochloride
Authors: Le Thanh-Nhu-Ngoc , Thuy-Ngan Nguyen T. , Nguyen Anh-Huy , Nguyen Phan-Thong , Nguyen Thao X.D , Le Minh-Vien
Published: May 2024

One of the majority of environmental pollution is caused by organic substances resulting from anthropogenic and industrial activities, such as dyes, antibiotics, and similar substances. Due to these pollutants’ strong stability, they are difficult to decompose, and their breakdown can only occur slowly through chemical or biological processes. Photocatalysis is a potential method for environmental clean-up with a significant oxidation capacity and a rapid response rate. Among them, double perovskite is an emerging alternative to single perovskite, which has recently shown comparable or even better performance for degrading organic pollutants. The first report on the synthesis of La2MnTiO6 (LMTO) double perovskite for tetracycline hydrochloride (TC) degradation was made in this work. By using XRD, FE-SEM, BET, and EDX analysis, the crystalline structure morphology, and elemental composition of the samples were identified. According to the calcination temperature, only at temperatures greater than 700 °C could the LMTO material be successfully formed. The photocatalytic performances of the prepared samples were evaluated by degrading TC under a UV LED lamp at 365 nm. The 800 °C calcined sample exhibited the highest TC degradation performance, reaching around 62% in 120 min. Besides, the LMTO might eliminate another medicine such as Ciprofloxacin (CIP). Overall, these results offer a potential strategy for employing LMTO photocatalysts to remove various antibiotics.
Impact of CO2 emissions on the economy of Vinh Tan 4 Extention Thermal Power Plant
Authors: Thoa Dao Thi Kim , Dang Nguyen Phan Minh , Luong Nguyen Huu
Published: May 2024

The increasing demand for modern living leads to an increasing demand for energy, including electricity. In Vietnam, the issue of electricity shortage has been addressed in the past five years. However, traditional electricity production methods have serious environmental consequences. While countries around the world are gradually closing down coal-fired power plants and switching to environmentally friendly electricity production, according to Vietnam’s recently issued Power Development Plan VIII, the proportion of coal-fired power plants is projected to account for approximately 31% by 2030 in the base-load scenario and around 28% in the high-load scenario. Vinh Tan 4 Extention Thermal Power Plant is part of Vinh Tan Power Plant Complex and was operated in late 2019. The amount of CO2 emissions has been calculated and the impact of CO2 emissions on economic efficiency and the environmental impact of coal-fired power generation has been assessed. This highlights the importance of transitioning to environmentally friendly electricity production methods in Vietnam. Therefore, it is necessary to calculate the amount of CO2 emissions from the power plant to assess the emission status and propose appropriate energy conversion methods.
Antioxidant and cytotoxic effects of isolated polysaccharides from cultured Ophiocordyceps sinensis
Authors: Huynh Thu , Tran Minh-Trang , Dinh Minh-Hiep
Published: May 2024

The Ophiocordyceps sinensis is well-known as a traditionally valued medicine. Recently, the cultured O. sinensis biomass have been producing and commercializing in Vietnam. Besides, the O. sinensis - isolated polysaccharides have been revealed possessing great biological activities, especially the potential antioxidant. Hence, this study focused on antioxidant activity and cytotoxicity of polysaccharides isolated from cultured O. sinensis biomass.

Methods: Firstly, crude polysaccharides (PS) including IPS (endo-polysaccharide extracted from biomass) and EPS (exo-polysaccharide extracted from broth) were isolated from O. sinensis, respectively. Then, the crude IPS and EPS were separated into fractions using a Sephadex G-200 column with a flow rate of 0.6 ml/min. The PSs and their fractions including IPS-1, IPS-2 and EPS-1, EPS-2 were screened for antioxidant (ABTS·+ free radical scavenging assay) and cytotoxic (HepG2 assay) activites.

Results: Both EPSs and IPSs were mixtures of peptide-polysaccharide. In the ABTS assay, the IC50 value of EPS and EPS-2 fractions were 2,688.80 ± 19.83 µg/ml and 1,885.90 ± 2.90 µg/ml, respectively. This result indicated that the antioxidant activity of EPS and EPS-2 fractions were higher than that of IPSs as well as EPS-1 fraction. Furthermore, only crude EPS exhibited HepG2 cell growth inhibitory ability (IC50 = 15.59 ± 0.17 µg/ml) among the samples. Taken together, the EPSs exhibited greater antioxidant and cytotoxic activity than the IPSs. Thus, the EPSs could be considered as an antioxidant source.
Watermarking algorithm based on phase-only CGH in fractional Hartley domain for DICOM images
Authors: Yadav Raman , Sachin  , Singh Phool
Published: May 2024

In this manuscript, we proposed a watermarking algorithm based on phase-only computer-generated holography (CGH) in the fractional Hartley domain for digital imaging and communications in medicine (DICOM) images. The proposed algorithm improves the security of the CGH-based algorithm. The cascaded use of fractional Hartley transform and attenuation factor

β

increases the keyspace of the proposed watermarking algorithm. The robustness and effectiveness of the proposed watermarking algorithm is validated using simulations on DICOM images. The effectiveness of the proposed watermarking algorithm is assessed using statistical tools in terms of mean-squared error, information entropy, correlation coefficient, histogram, and mesh plots. The robustness is evaluated by testing the proposed algorithm’s performance under real-time threats, including contamination and data loss attacks. Furthermore, the security of the proposed algorithm is also tested for existing cryptographic attacks, such as chosen-plaintext attacks, and known-plaintext attacks. The simulation results indicate that the proposed watermarking algorithm is robust and effective.
Hot-carrier thermophotovoltaic systems
Authors: Nimje Kartika N , Giteau Maxime , Papadakis Georgia T
Published: May 2024

A thermophotovoltaic (TPV) energy converter harnesses thermal photons emitted by a hot body and converts them to electricity. When the radiative heat exchange between the emitter and photovoltaic cell is spectrally monochromatic, the TPV system can approach the Carnot thermodynamic efficiency limit. Nonetheless, this occurs at the expense of vanishing extracted electrical power density. Conversely, a spectrally broadband radiative heat exchange between the emitter and the cell yields maximal TPV power density at the expense of low efficiency. By leveraging hot-carriers as a means to mitigate thermalization losses within the cell, we demonstrate that one can alleviate this trade-off between power density and efficiency. Via detailed balance analysis, we show analytically that one can reach near-Carnot conversion efficiencies close to the maximum power point, which is unattainable with conventional TPV systems. We derive analytical relations between intrinsic device parameters and performance metrics, which serve as design rules for hot-carrier-based TPV systems.
Creating the Victim: From Innocent Victims to Indebted Subjects
Authors: Ullrich Leila
Published: May 2024

This chapter asks why people in Kenya and Uganda engage in the Court’s processes, and what that engagement does to them. The question of how the Court relates to affected communities and victims has been mainly studied through the concept of legitimacy. Challenging this approach, I instead propose to read the Court’s victim engagement through critical ideology theory. On that basis, I argue that the Court’s victim engagement works by creating its own victim subjects. I first illustrate how victims are ‘spotlighted’, ‘lured’, ‘schooled’, and ‘blamed’ in their encounter with the Court, and then focus on what subject is produced in the process. Rather than passive victims, the Court creates active victim subjects (‘champions’) and, rather than ‘innocent victims’, the Court creates blameworthy victims. I will illuminate this process of ideological subject formation through the notion of the blame cascade. What makes blame stick to victims is the fusion of moral and material processes: through assistance and reparation programmes, victims are incorporated into labour and debt relationships, which reconstruct them as ‘lazy’, ‘unproductive’, and ‘unreliable’.
Money and Land: Resistance in Times of Capitalist Complementarity
Authors: Ullrich Leila
Published: May 2024

A key question scholars often ask about international criminal justice is whether affected communities support or oppose it. Do they want international criminal trials or rather domestic trials, truth and reconciliation commissions, or local justice rituals? This question overlooks that many people, supportive or critical, are willing to engage with the Court. They come to the Court’s meetings and enter into relationships with the Court’s staff and intermediaries. For that reason, it is important to study what people do and not only what they say. What I noticed observing the Court’s victims and outreach meetings in Kenya and Uganda is that victims often come late to the meetings, they bring along their children and people who were not invited by the Court, they haggle about transport reimbursement, and they forget what they were taught last time by the victims’ lawyers. Their lives centre around subsistence and social reproduction and that shapes their engagement with the Court. From this vantage point, this chapter will reread resistance to international criminal justice drawing on ideology and social reproduction theory. Such a rereading, first, suggests that, rather than a blanket refusal to engage, resistance often manifests in victims’ attempts to redefine the relationship with the Court. Secondly, it demonstrates how in mixed economies in the Global South that combine market and subsistence production, and where women still have access to communal land, social reproduction can become a means of resistance to global governance and its colonial capitalist relations, making women key agents of resistance.