bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Development and Field Validation of Rock Anchors for Sustainable Onshore Foundations
Authors: Suchorzewski Jan , Flansbjer Mathias , Chaudhari Ojas , Williams Portal Natalie 
Published: May 2024

Abstract
The development of an innovative rock anchor prototype manufactured using high strength steel sheets produced locally in Sweden is the core of the PROWIND concept. Steel sheets provide a design freedom to easily manufacture complex geometries, which can be advantageous to enhance the shear force transmission in the bond-length segment of the anchor. The underlying challenge of this concept has been to design a solution which meets the design requirements of today and future technological advancements, all while keeping conventional installation practices in mind. The project followed a 4-step development process: (1) concept analysis and modelling, (2) small-scale prototypes testing and (3) large scale lab-validation and lastly (4) field validation. The performance of the developed rock anchor prototype and grouting material was experimentally quantified on both small and large-scale test specimens and also validated in full scale in the field concerning installation process, proof-loading and maintaining the prestress over time. The PROWIND anchors with the end feature with ribbed design have 4-5 times higher load bearing capacity. The experience from the anchor installation proved that the developed grout and anchors are faster and easier to install. The field test in two different geological conditions has proven that the news design is reducing the required anchorage length to just 1 meter. The restressing of anchors is fully possible with the proposed lock-off solution with a nut. All of those contribute to lower costs of installations and possibly longer service-life.
Scalable SCADA-Based Calibration for Analytical Wake Models Across an Offshore Cluster
Authors: Binsbergen Diederik van , Daems Pieter-Jan , Verstraeten Timothy , Nejad Amir , Helsen Jan 
Published: May 2024

Abstract
A multi-level hyperparameter optimization framework is performed to calibrate analytical wake models in the context of multiple wind farms within the Belgian-Dutch offshore cluster. The calibration, applied on the TurbOPark model with Gaussian wake profile, is performed on different scales. Initially, calibration focused solely on internal wake effects, followed by a calibration for individual wind farms, considering both internal and external wake effects, and finally performing the calibration using SCADA data from multiple wind farms within the concession zone, with and without accounting for blockage. It was observed that calibrating wakes for freeflow wind directions using internal wakes only results in tuning parameters similar to the calibration involving both intra-and-inter farm wake effects. Minor variations are noted between wind farms, with dependencies on wind speed and wind direction across all cases. When the tuning parameter is calibrated using SCADA data from multiple wind farms, a significant reduction in the tuning parameter was observed, compared to calibration that focuses on one wind farm per calibration. Analyzing the model residual error for wind coming from the north-west reveals that the calibrated wake model effectively accounts for cluster wake effects. Furthermore, a consistent and substantial presence of heterogeneous inflow perpendicular to the wind direction originating from the south-west is observed, which is not captured by the modeling framework, which assumes homogeneous inflow. The observed trend of inflow heterogeneity suggests that the discrepancy cannot be attributed solely to blockage effects.
Enhancing standard CFD based practices for site assessment through polynomial surrogates for estimating uncertainty in wind speed
Authors: Lakdawala Zahra , Kassem Hassan , Schulte Jonas 
Published: May 2024

Abstract
One of the challenges in digitizing the wind energy sector is to have reliable, accurate and efficient data assessment and prediction tools. We believe that accurate surrogates are key towards improving efficiency and reliability for informed decision making. For a quantitative understanding of wind and energy in complex terrains, a detailed site assessment is done, most often using mesoscale and/or microscale computational fluid dynamics (CFD) based approach. Typically, one would require multiple scenarios/case for a CFD simulator to incorporate the influence of a parameter on variability of wind speed and energy production. These simulations are computationally expensive, and the industry is constantly on a look out for more efficient methods. Towards this end, we propose using a polynomial surrogate based on Polynomial Chaos Expansion (PCE) for uncertainty quantification that requires only a few CFD simulations to assess the variability of wind speed with respect to variability in an input parameter. The variability estimates from PCE were first validated against the standard Monte Carlo method on simple benchmarks and then tested for complex terrains. In this work, we present results that help us understand how canopy foliage, particularly its height, impacts the variability in wind speed in complex terrains. Since the polynomial surrogate relies only on a limited set of input variations (forest height) to estimate the variability distributions for wind speed locally (for specified points of interests), it has proven to be a low-cost and accurate method for estimating uncertainty. In this paper, we discuss the results for wind speed variability for five sites with varying complexity using the polynomial surrogate model. Furthermore, the singular value decomposition (SVD) entropy value is used to quantify terrain complexity for the sites considered. We show how the variability in wind speed can potentially be correlated to terrain complexity. This is our first attempt in providing an empirically (including multiple sites) derived relationship that can be used as a basis for fast and reliable variability estimator for wind resource planners.
Linking the microstructure with strain-life curves for improved utilization of the lightweight potential of thick-walled nodular cast iron
Authors: Pittel C , Niewiadomski J , Bleicher C 
Published: May 2024

Abstract
The assessment of the fatigue life of critical, highly stressed component areas is an important aspect in the design of thick-walled components for wind turbines made of nodular cast iron. With the demand for resource efficiency through lightweight design combined with a certain capability to withstand extreme loads and special events, this issue is becoming increasingly important. However, there are still gaps in the description of local strain-based material behaviour. For the design and local strain-based fatigue assessment of large cast components, possibilities to determine the fatigue life as accurately as possible must be provided by standards and guidelines. The paper aims to provide a wide range of material and fatigue data from one common source for general design interests. During research projects at Fraunhofer LBF, material properties for the PRAM-based fatigue life assessment and the elastic-plastic material behaviour have been derived from 9 nodular cast iron grades with 44 microstructural variations. To describe the influence of the technological size effect on cyclic stress-strain and PRAM-N curves the quasi-static parameters (tensile strength and elongation at break) and the microstructure (nodularity and graphite particle density) are considered. In addition, suggestions for scatter bands in the strain-based design approach are given to the designers of thick-walled GJS components.
The compatibility of nitrided W18Cr4V steel in a sodium environment
Authors: Fu Xiaogang , Liang Na , Zhang Wei , Tao Liu , Qin Bo , Ruan Zhangshun , Long Bin 
Published: May 2024

Abstract
The guideway friction pairs are the key components of the loading elevator and unloading elevator in the refueling system for sodium cooled fast reactor. With the excellent hardness and wear resistance in air, nitrided W18Cr4V steel is a candidate material for the guideway friction pairs. In order to evaluate the applicability in the high-temperature sodium, it is important to conduct the compatibility tests of nitrided W18Cr4V steel for different exposure time. The results show that the nitrogen content of nitrided W18Cr4V steel decreased obviously after 1000 h, 2000 h and 3000 h sodium compatibility tests at 540 °C and the nitrided strengthening effect of W18Cr4V steel gradually decreased with the test duration increasing.
Advancements in perovskite solar cell efficiency through blade coating techniques and post-treatment optimization
Authors: Qiang Ziyue , Wu Yao , Wang Caixia , Gao Xiang , Li Jihong , Sun Shuang , Dong Ningbo , Jiang Jun , Zhao Xiaoxia 
Published: May 2024

Abstract
Addition of lead chloride (PbCl2) improves the crystallization kinetics of perovskites by suppressing the formation of δ-phase during large-area perovskite film fabrication. However, this addition results in formation and accumulation of lead iodide (PbI2) platelet atop the film, which adversely affects carrier transport. To eliminate the negative effect of PbI2 accumulation and simultaneously obtain a dense, mirror-like perovskite film, a post-treatment method involving blade coating formamidinium iodide (FAI) under air atmosphere is used. Instead of being washed away, as reported in literatures using spin coating process, PbI2 platelets are converted into cesium lead halide perovskites (CsPbX3) through reaction with Cs and halide present in the original perovskite Cs0.22FA0.78Pb(I0.85Br0.15)3. An efficiency enhancement of (>10%) is achieved by FAI treatment, which does not require fast solvent removal or nitrogen (N2) atmospheres, indicating that FAI blade coating is an effective and straightforward method for the post-treatment of excess PbI2.
Forgetfulness of turbulent energy cascade associated with different mechanisms
Authors: Araki Ryo , Vela-Martín Alberto , Lozano-Durán Adrián 
Published: May 2024

Abstract
The small scales of high Reynolds number turbulence exhibit the statistical universality by forgetting about the large scales during the energy cascade. In this study, we revisit this schematic description with an information-theoretic point of view. Our objective is to understand the importance of different cascade mechanisms in this process. To this end, we compute the “information flux”, the information-theoretic measure of causality formulated by one of the authors, of the decomposed inter-scale energy transfer. For the kinetics, the ratio of the inertial-range inter-scale energy transfer between the strain self-amplification (SSA) and the vortex stretching (VS) mechanisms is 5 : 3. However, for the information-flux, the VS contribution is roughly twice as large as the SSA. We also find several deviations between the kinetics and the informatics, highlighting the nontrivial nature of information distributed among different scales and mechanics in turbulence. This result infers that the SSA is a less efficient mechanism than the VS in terms of information transfer, and contributes to losing the large-scale information.
Predictability of decay events in transitional wall-bounded flows
Authors: Morón Daniel , Vela-Martín Alberto , Avila Marc 
Published: May 2024

Abstract
Extreme events in turbulent flows are in general linked with sudden changes in the dynamics of the system. Despite the increasing interest in modelling these events, their predictability remains largely unexplored. Here we focus on the case of sudden turbulence/chaos decay in pipe flow and in a reduced-order model of shear flows (Moehlis, Faisst and Eckhardt, 2004). We study the predictability of decay events with massive ensembles of simulations. For this purpose we introduce a new pseudo-spectral GPU code to perform fast simulations of turbulent pipe flow and describe a methodology to characterize predictability of decay events using the results of the ensembles of simulations. We report the decrease of predictability as one goes back in time with respect to a decay event, and show that this decrease does not need to be monotonic.
The role of nonlinear interactions in the onset of drag increase in flow over riblets
Authors: Viggiano B , Camobreco C J , Wong J , Luhar M , García-Mayoral R , Chung D , Gayme D 
Published: May 2024

Abstract
Characterizing the mechanisms that contribute to the onset of drag increase over micro-grooves (riblets) as the spacing increases is critical to design strategies for riblet-based drag reduction. This study decomposes the roughness function to investigate different mechanisms associated with the breakdown of drag reduction as riblet spacing is increased. We obtain the roughness function through direct numerical simulations (DNS) in a minimal channel and restricted nonlinear (RNL) models. Both the traditional RNL decomposition and an augmented RNL (ARNL) model that includes additional nonlinear interactions are employed as computationally tractable, reduced order representations of the flow field. RNL and ARNL results are compared to those of DNS in minimal channels to investigate the role of the different scale-dependent nonlinear interactions contributing to the roughness function. A comparison of the co-spectra arising from the minimal channel DNS with that from RNL and ARNL simulations indicates that general trends are captured by both reduced order models. However, the additional nonlinearity introduced in the ARNL model produces closer correspondence in the observed structural features of the DNS results. In particular, the ARNL better captures the signatures of the dispersive flow and the texture-coherent fluctuations. There is also a noticeable improvement observed in the profiles of the added stress contributions obtained with the ARNL model versus the RNL model.
Periodic bursting cycles on the edge to square duct turbulence
Authors: Scherer Markus , Uhlmann Markus , Kawahara Genta 
Published: May 2024

Abstract
The long-time behaviour of trajectories embedded in the edge manifold between the laminar and turbulent basins of attraction is investigated in order to identify simple invariant solutions to the Navier-Stokes equations in straight ducts with square cross-section. With the aid of the iterative bisection procedure of Toh and Itano (J. Fluid Mech., vol. 481, 2003, pp. 67-76), we detect three travelling waves that represent attracting ‘edge states’ within the separatrix and saddles w.r.t. the full state space. All three travelling waves are presumably connected to solutions known in the community. In other situations, the edge states to which trajectories are attracted seem to be invariant periodic cycles that feature a rich dynamics: Along each cycle, the flow oscillates periodically between two flow states, in each of which streamwise vorticity is predominantly residing near one set of parallel walls, while the vortical activity associated to the other pair of opposing walls is markedly reduced. This ‘switching’ dynamics is accompanied by intermittent bursting-like high-dissipation excursions. While we cannot rigorously prove that the identified periodic cycle is a periodic orbit rather than a finite-precision approximation to a heteroclinic cycle, sound arguments for the former supposition are given. Interestingly, the different phases of the periodic cycle qualitatively resemble a similar ‘switching’ behaviour observed in (chaotic) marginal turbulence, which suggests that the found periodic cycles could help understanding the characteristic dynamics of duct turbulence at low Reynolds numbers.
Prediction of turbulent energy based on low-rank resolvent modes and machine learning
Authors: Fan Yitong , Chen Bo , Li Weipeng 
Published: May 2024

Abstract
A modelling framework based on the resolvent analysis and machine learning is proposed to predict the turbulent energy in incompressible channel flows. In the framework, the optimal resolvent response modes are selected as the basis functions modelling the low-rank behaviour of high-dimensional nonlinear turbulent flow-fields, and the corresponding weight functions are determined by data-driven neural networks. Turbulent-energy distribution in space and scales, at the friction Reynolds number 1000, is predicted and compared to the data of direct numerical simulation. Close agreement is observed, suggesting the feasibility and reliability of the proposed framework for turbulence prediction.
Matrix numerical method for probability densities of stochastic delay differential equations
Authors: Antary Nils , Holubec Viktor 
Published: May 2024

Abstract
Stochastic processes with time delay are invaluable for modeling in science and engineering when finite signal transmission and processing speeds can not be neglected. However, they can seldom be treated with sufficient precision analytically if the corresponding stochastic delay differential equations (SDDEs) are nonlinear. This work presents a numerical algorithm for calculating the probability densities of processes described by nonlinear SDDEs. The algorithm is based on Markovian embedding and solves the problem by basic matrix operations. We validate it for a broad class of parameters using exactly solvable linear SDDEs and a cubic SDDE. Besides, we show how to apply the algorithm to calculate transition rates and first passage times for a Brownian particle diffusing in a time-delayed cusp potential.
On the nonlinear electrodynamics in a Lorentz-breaking scenario
Authors: Neres Júnior E , Felipe J C C , Baêta Scarpelli A P 
Published: May 2024

Abstract
In this work, we study a model in nonlinear electrodynamics in the presence of a CPT-even term that violates Lorentz symmetry. The Lorentz-breaking vector, in addition to the usual background magnetic field, produces interesting effects in the dispersion relations. The consequences on the vacuum refractive index and the group velocity are studied. Vacuum birefringence is discussed in the case the nonlinear electrodynamics is a Euler–Heisenberg model.
Impact of breath sample collection method and length of storage of breath samples in Tedlar bags on the level of selected volatiles assessed using gas chromatography-ion mobility spectrometry (GC-IMS)
Authors: Czippelová Barbora , Nováková Slavomíra , Šarlinová Miroslava , Baranovičová Eva , Urbanová Anna , Turianiková Zuzana , Krohová Jana Čerňanová , Halašová Erika , Škovierová Henrieta 
Published: May 2024

Abstract
The analysis of volatile organic compounds (VOCs) in exhaled air has attracted the interest of the scientific community because it provides the possibility of monitoring physiological and metabolic processes and non-invasive diagnostics of various diseases. However, this method remains underused in clinical practice as well as in research because of the lack of standardized procedures for the collection, storage and transport of breath samples, which would guarantee good reproducibility and comparability of results. The method of sampling, as well as the storage time of the breath samples in the polymer bags used for sample storage and transport, affect the composition and concentration of VOCs present in the breath samples. The aim of our study was to compare breath samples obtained using two methods with fully disposable equipment: a Haldane sampling tube intended for direct breath collection and breath samples exhaled into a transparent Tedlar bag. The second task was to monitor the stability of selected compounds of real breath samples stored in a Tedlar bag for 6 h. Gas chromatography coupled with ion mobility spectrometry (GC-IMS) implemented in the BreathSpec® device was used to analyse exhaled breath. Our results showed a significant difference in the signal intensity of some volatiles when taking a breath sample with a Haldane tube and a Tedlar bag. Due to its endogenous origin, acetone levels were significantly higher when the Haldane tube sampler was used while elevated levels of 2-propanol and unidentified VOC (designated as VOC 3) in the Tedlar bag samples likely originated from contamination of the Tedlar bags. The VOC stability study revealed compound-specific signal intensity changes of the selected VOCs with storage time in the Tedlar bags, with some volatiles showing increasing signal intensity during storage in Tedlar bags. This limits the use of Tedlar bags only for very limited time and carefully selected purpose. Our results highlight the importance of careful design and implementation of experiments and clinical protocols to obtain relevant and reliable results.
Analysis of Water Conservation Priority Locations in Upper Sub Watershed
Authors: Anggraini E , Yuliastuti N , Budihardjo M A 
Published: May 2024

Abstract
Water is useful for supplying household, industrial, and agricultural needs. The availability of water supports food security and decent life. The process of sustaining water resources requires conservation, which is in line with sustainable development goals. The Keyang sub watershed is one of the catchment areas of the Upstream Madiun River, located in East Java. The development of agriculture land in Keyang sub watershed increases the number of disasters. The Central Statistics Office of Ponorogo Regency recorded 24 floods, 11 drought disasters, and 42 landslides in Keyang sub watershed during 2020. Floods and drought disasters in the same location show strong fluctuations in water resources, so Keyang sub watershed requires water conservation actions. The aim of this study is to analyze priority locations for water conservation. Indicateurs de Ruissellement Intense Pluvial (IRIP) is a method for determining water conservation priority locations. IRIP divides surface runoff vulnerability area into three types: generation area, transfer area, and accumulation area. Each area requires different adaptations to conservation techniques. The result shows that Keyang sub watershed has 4.96% strong potential surface runoff generation area. This priority area is suitable for wetland development, agroforestry, and sustainable agriculture. Then, Keyang sub watershed has 0.03% strong potential area of surface runoff transfer, this area is compatible with prevention of erosion and landslides. Keyang sub watershed has 0.63% very strong potential and 18.42% strong potential for surface runoff accumulation area. Accumulation area appropriate for developing flood mitigation strategies.
A design framework for Food Small Medium Enterprises resilience and performance in Indonesia
Authors: Dewi Heptari Elita , Muhaimin Abdul Wahib , Setiawan Budi , Maulidah Silvana 
Published: May 2024

Abstract
For small and medium-sized businesses (SMEs) in Indonesia, the post-pandemic economic challenges are particularly severe, even with the numerous government initiatives that have been put into place over the last two years. Most SMEs, including food SMEs, are finding it difficult to overcome the health crisis and the uncertainty of impending economic difficulties. While food SME players must concentrate on their business performance—both financial and non-financial, such as environmental performance—in order to survive and endure in the competitive landscape. The aim of this paper is to identify resilience factors and performance measurement for food SMEs in Indonesia that are facing economic challenges. Using a literature review, this paper recommends a framework that integrates food SME resilience factors with business market challenges identified in Indonesia as drivers of food SMEs performance. Additionally, this paper offers researchers and policy makers a framework for creating plans that will increase the performance and resilience of food SMEs. This research implies that in order to improve food SMEs performance, actors must work together and in concert.