bluuebunny/crossref_metadata_2025 huggingface dataset:
Unraveling the Complexities of Immune Checkpoint Inhibitors in Hepatocellular Carcinoma
Authors: Han Xinpu , Sun Qianhui , Xu Manman , Zhu Guanghui , Gao Ruike , Ni Baoyi , Li Jie
Published: November 2023

Immune checkpoint inhibitors (ICIs) have emerged as effective therapeutics for multiple cancers. Nevertheless, as immunotherapeutic approaches are being extensively utilized, substantial hurdles have arisen for clinicians. These include countering ICIs resistance and ensuring precise efficacy assessments of these drugs, especially in the context of hepatocellular carcinoma (HCC). This review attempts to offer a holistic overview of the latest insights into the ICIs resistance mechanisms in HCC, the molecular underpinnings, and immune response. The intent is to inspire the development of efficacious combination strategies. This review also examines the unconventional response patterns, namely pseudoprogression (PsP) and hyperprogression (HPD). The prompt and rigorous evaluation of these treatment efficacies has emerged as a crucial imperative. Multiple clinical, radiological, and biomarker tests have been advanced to meticulously assess tumor response. Despite progress, precise mechanisms of action and predictive biomarkers remain elusive. This necessitates further investigation through prospective cohort studies in the impending future.
The six-degrees-of-freedom attitude measurement instrument for the large aperture mirror using the prepressing sensors and flexible supporting
Authors: Xu Zhenyuan , Li Fei , Ma Wenjing , Yang Kaike , Luo Junpeng , Zhang Junwei , Wang Xi
Published: November 2023

To achieve precise measurement of a large aperture mirror, a six-degrees-of-freedom (6-DOF) measurement instrument is designed to monitor and calculate the real-time attitude of the mirror. Magnetoelectric displacement sensors are prepressed, and a flexible sensor supporting is designed to achieve high-accuracy measurement. The relationship between 6-DOF displacements of the mirror and the six sensor values can be obtained using the coordinate system transformation and Jacobian matrix. The Newton’s iteration method is used to decouple the strong coupling measurement system, and 6-DOF displacements are obtained. The displacements directly measured by using laser sensors are compared with the calculated values in the experiments, the minimum average error of the measured displacement is 1.87%, and the mean difference of the displacement is 0.43 µm.
Random-hopping approach to fluctuation phenomena in quantum dots with chiral symmetry
Authors: Pessoa N. L. , Barbosa A. L. R. , Macêdo A. M. S.
Published: November 2023

We propose a numerical approach to study mesoscopic fluctuations in quantum dots with chiral symmetry. Our method involves applying the random-hopping model to a tight-binding Hamiltonian, allowing us to calculate the conductance and shot-noise power distributions for systems belonging to the three chiral symmetry classes of random matrix theory. Furthermore, we demonstrate that the spectral fluctuations of quantum dots belonging to the Wigner–Dyson symmetry classes of random matrix theory can be obtained by applying the random-hopping model to a scattering region that was originally integrable, thus bypassing the need to use the boundaries of chaotic billiards.
Numerical simulation of tubular piezoceramics-based smart aggregate embedded in asphalt mixture for health monitoring
Authors: Guo Shenghao , Tang Ning
Published: November 2023

Health monitoring plays an important role in the maintenance of asphalt pavement. Tubular smart aggregate (TSA) is a cylindrical sensor composed of lead zirconate titanate (PZT) and protective coating. Ultrasonic waves are produced when the TSA vibrates and can be used to monitor the health of asphalt pavement. The influence of the protective coating material of the TSA, elastic modulus of PZT, and diameter of the TSA on the TSA resonant frequency was studied. A voltage signal and mechanical load were applied to the TSA; vibration and the received voltage of the TSA were collected. Furthermore, two TSAs were embedded in an asphalt mixture to transmit and receive ultrasonic waves. The vibration and generated voltage by the TSA embedded in the asphalt mixture were collected. Results indicate that the resonant frequency of the TSA increases with the increase of the elastic modulus of protective coating and PZT. With the increase of the diameter of the TSA, the resonant frequency of the TSA decreases gradually. When the voltage signal and mechanical load subjected to the TSA were close to the resonant frequency of the TSA, larger vibration and voltage were generated. Due to the viscoelasticity of the asphalt mixture, the resonant frequency of the TSA embedded in an asphalt mixture was reduced.
Recent advances in hydrodynamics of wing propulsive lifting systems for ships and underwater vehicles
Authors: Rozhdestvensky Kirill , Zhao Bowen
Published: November 2023

A collaborative and interdisciplinary strategy spanning hydrodynamics, sophisticated materials, elasticity, and microelectromechanical systems technologies is required for the effective deployment of wing propulsive lifting systems in ships and underwater vehicles. The hydrodynamic characteristics play a crucial role in the motion performance of the marine vehicle, which employs a wing propulsive lifting system. The present study aims at reviewing the hydrodynamics of the wing propulsive lifting system for ships and underwater vehicles, covering the relevant classical work, mathematical models, numerical simulations, and experimental results. This study contributes to the academic discourse by conducting a meticulous examination of the hydrodynamics underlying wing propulsive lifting systems. The classification of research methods enables a comprehensive comparison of results, facilitating accurate performance evaluation. The review concludes by presenting key insight and recommending potential avenues for future research, thereby propelling the knowledge and development of wing-propulsive lifting systems within the scholarly community.
libMBD: A general-purpose package for scalable quantum many-body dispersion calculations
Authors: Hermann Jan , Stöhr Martin , Góger Szabolcs , Chaudhuri Shayantan , Aradi Bálint , Maurer Reinhard J. , Tkatchenko Alexandre
Published: November 2023

Many-body dispersion (MBD) is a powerful framework to treat van der Waals (vdW) dispersion interactions in density-functional theory and related atomistic modeling methods. Several independent implementations of MBD with varying degree of functionality exist across a number of electronic structure codes, which both limits the current users of those codes and complicates dissemination of new variants of MBD. Here, we develop and document libMBD, a library implementation of MBD that is functionally complete, efficient, easy to integrate with any electronic structure code, and already integrated in FHI-aims, DFTB+, VASP, Q-Chem, CASTEP, and Quantum ESPRESSO. libMBD is written in modern Fortran with bindings to C and Python, uses MPI/ScaLAPACK for parallelization, and implements MBD for both finite and periodic systems, with analytical gradients with respect to all input parameters. The computational cost has asymptotic cubic scaling with system size, and evaluation of gradients only changes the prefactor of the scaling law, with libMBD exhibiting strong scaling up to 256 processor cores. Other MBD properties beyond energy and gradients can be calculated with libMBD, such as the charge-density polarization, first-order Coulomb correction, the dielectric function, or the order-by-order expansion of the energy in the dipole interaction. Calculations on supramolecular complexes with MBD-corrected electronic structure methods and a meta-review of previous applications of MBD demonstrate the broad applicability of the libMBD package to treat vdW interactions.
Wavelength manipulation in shallow water via space transformation method
Authors: Zhang Zhigang , He Guanghua , Gou Ying , Luan Zhengxiao , Liu Shuang , He Runhua
Published: November 2023

Wavelength is an important component of water waves. Realizing the active control of wavelength is of great significance for the protection of offshore structures and the development of wave energy. In this study, a circular wavelength modulator is proposed based on the space transformation method, which can reduce or amplify the wavelength arbitrary. The transformed spaces of a wavelength reducer and a wavelength amplifier are designed. According to the form invariance of the water-wave governing equation, the anisotropic medium parameters including water depth and gravity acceleration in the modulation fields are obtained, which means the wave control can be realized in ordinary spaces instead of in the deformed transformed spaces. The wave distributions in the modulation fields are calculated by solving the Helmholtz equation to validate the proposed wavelength modulator. It is found that the wavelength can be manipulated as expected with the anisotropic medium. In addition, the results show that the wavelength is controlled due to the scattering of the anisotropic medium. Moreover, the proposed wavelength modulator is frequency independent and omnidirectional.
Advancements in early detection of diabetes and diabetic retinopathy screening using artificial intelligence
Authors: Deepa R. , Sivasamy A.
Published: November 2023

This paper explores the synergy between early diabetes detection and artificial intelligence (AI)-based diabetic retinopathy screening. It emphasizes the crucial role of integration for enhancing patient care. Diabetes and its complications, such as diabetic retinopathy, can be better managed with early intervention. AI techniques are revolutionizing medical diagnostics, offering potential for accurate prediction of diabetes risk and automated analysis of retinal images for retinopathy detection. By combining these aspects, we uncover a comprehensive strategy that not only identifies diabetes in its early stages but also ensures timely management of its ocular complications. This integrated approach shows promise for personalized care, improved outcomes, and efficient resource utilization. This paper underscores the need for collaboration between medical and AI experts to maximize the potential of this dual-focused approach for transforming diabetes management.
On the probability of down-crossing and up-crossing rogue waves
Authors: Slunyaev Alexey V. , Kokorina Anna V.
Published: November 2023

By means of the direct numerical simulation of directional waves on the surface of deep water, it is shown that extreme waves can exhibit such asymmetry that the occurrence of deeper troughs is several times more likely on the wave rear slopes. This effect becomes most pronounced in the case of steep short-crested waves. It is not related to the Benjamin–Feir instability but is a result of complex contribution from nonlinear combination harmonics, mainly cubic in nonlinearity. The discovered asymmetry can lead to remarkably different estimates of the rogue wave probability based on either down- or up-zero-crossing methods for individual wave selection, commonly used in the oceanography.
Enhanced ferromagnetism, magnetic anisotropy, and spin polarization in Janus CrSeTe via strain and doping
Authors: Liu Yuqi , Zhang Long , Wu Xuming , Gao Guoying
Published: November 2023

Recently, experimental 2D magnetic CrSe2 and CrTe2 inspired the study on their Janus CrSeTe, which breaks the mirror symmetry of Cr–Se(Te)–Cr. However, the CrSeTe monolayer possesses a lower Curie temperature and the in-plane magnetic anisotropy, and few works concerned both its zigzag- and stripy-antiferromagnetic states, which are crucial to determine the magnetic ground state and magnetic transition temperature. In this Letter, using first-principles calculations and Monte Carlo simulations, we systematically explore the strain, carrier-doping, and electric field effects on magnetic and electronic properties of monolayer CrSeTe. We demonstrate that monolayer CrSeTe preserves ferromagnetism in a large range of whether strain or doping. The estimated Curie temperature can be increased from 167 K to the room-temperature by the combination of 4% tensile strain and 0.1 e doping due to the enhanced ferromagnetic Cr–Se(Te)–Cr super-exchange interaction. Interestingly, either a small tensile strain (1%) or a low hole doping (0.025 h) can induce the transition of the easy axis from in-plane to out-of-plane due to the increased out-of-plane magnetic anisotropy from hybridized pz and py orbitals of Te atoms. In addition, the spin polarization is improved by over 60% by the tensile strain. Our results suggest that small strain and low carrier-doping induced room-temperature ferromagnetism, large out-of-plane magnetic anisotropy, and high spin polarization make CrSeTe useful in 2D spintronic applications and will stimulate broad studies on the regulation of magnetic and electronic properties of this class of magnetic Janus monolayers.
Fast electron damage mechanism of epoxy resin studied by electron energy loss spectroscopy and electron diffraction
Authors: Kikkawa Jun , Nii Aoi , Sakaniwa Yoshiaki , Kon Naochika , Sakamaki Marina , Ohashi Touyou , Nita Nobuyasu , Harano Koji , Kimoto Koji
Published: November 2023

The damage mechanism and exposure tolerance of epoxy resins to fast electrons remain unclear. We quantitatively investigated the effects of electron irradiation on a common epoxy resin by dose-dependent electron energy loss spectroscopy. The results show that sp3 states of nitrogen, oxygen, and their adjacent carbon atoms were converted to sp2 states, forming imine (C=N) and carbonyl (C=O) as the total electron dose increased. The sp3 to sp2 conversion mechanism was proposed. The epoxy resin was very sensitive to fast electrons and the original electronic states were maintained up to a total dose of ∼103e− nm−2 at a low temperature of 103 K. Dose-dependent electron diffraction revealed that the intra- and intermolecular geometries changed below and around the total dose of ∼103e− nm−2.
Rats respond to aversive emotional arousal of human handlers with the activation of the basolateral and central amygdala
Authors: Kaźmierowska Anna M. , Kostecki Mateusz , Szczepanik Michał , Nikolaev Tomasz , Hamed Adam , Michałowski Jarosław M. , Wypych Marek , Marchewka Artur , Knapska Ewelina
Published: November 2023

Reading danger signals may save an animal’s life, and learning about threats from others allows avoiding first-hand aversive and often fatal experiences. Fear expressed by other individuals, including those belonging to other species, may indicate the presence of a threat in the environment and is an important social cue. Humans and other animals respond to conspecifics’ fear with increased activity of the amygdala, the brain structure crucial for detecting threats and mounting an appropriate response to them. It is unclear, however, whether the cross-species transmission of threat information involves similar mechanisms, e.g., whether animals respond to the aversively induced emotional arousal of humans with activation of fear-processing circuits in the brain. Here, we report that when rats interact with a human caregiver who had recently undergone fear conditioning, they show risk assessment behavior and enhanced amygdala activation. The amygdala response involves its two major parts, the basolateral and central, which detect a threat and orchestrate defensive responses. Further, we show that humans who learn about a threat by observing another aversively aroused human, similar to rats, activate the basolateral and centromedial parts of the amygdala. Our results demonstrate that rats detect the emotional arousal of recently aversively stimulated caregivers and suggest that cross-species social transmission of threat information may involve similar neural circuits in the amygdala as the within-species transmission.
Analytic Hall magnetohydrodynamics toroidal equilibria via the energy-Casimir variational principle
Authors: Giannis A , Kaltsas D A , Throumoulopoulos G N
Published: November 2023

Equilibrium equations for magnetically confined, axisymmetric plasmas are derived by means of the energy-Casimir variational principle in the context of Hall magnetohydrodynamics (MHD). This approach stems from the noncanonical Hamiltonian structure of Hall MHD, the simplest, quasineutral two-fluid model that incorporates contributions due to ion Hall drifts. The axisymmetric Casimir invariants are used, along with the Hamiltonian functional to apply the energy-Casimir variational principle for axisymmetric two-fluid plasmas with incompressible ion flows. This results in a system of equations of the Grad–Shafranov–Bernoulli (GSB) type with four free functions. Two families of analytic solutions to the GSB system are then calculated, based on specific choices for the free functions. These solutions are subsequently applied to Tokamak-relevant configurations using proper boundary shaping methods. The Hall MHD model predicts a departure of the ion velocity surfaces from the magnetic surfaces which are frozen in the electron fluid. This separation of the characteristic surfaces is corroborated by the analytic solutions calculated in this study. The equilibria constructed by these solutions exhibit favorable characteristics for plasma confinement, for example they possess closed and nested magnetic and flow surfaces with pressure profiles peaked at the plasma core. The relevance of these solutions to laboratory and astrophysical plasmas is finally discussed, with particular focus on systems that involve length scales on the order of the ion skin depth.
A discrete discontinuity between the two phases of gravity
Authors: Sengupta Sandipan
Published: November 2023

When tetrad (metric) fields are not invertible, the standard canonical formulation of
gravity cannot be adopted as it is. Here we develop a Hamiltonian theory of gravity for
noninvertible tetrad. In contrast to Einstein gravity, this phase is found to exhibit three
local degrees of freedom. This reflects a discrete discontinuity in the limit of a vanishing
tetrad determinant. For the particular case of vanishing lapse, the Hamiltonian constraint
disappears from the classical theory upon fixing the torsional gauge-freedom. Any state
functional invariant under the internal gauge rotations and spatial diffeomorphisms is a formal solution of the associated quantum theory. The formulation here provides a Hamiltonian
basis to analyze gravity theory around a physical singularity, which corresponds to a zero of
the tetrad determinant in curved spacetime.
Evaluation of long-term robustness of the International System of Reference (SIR) used in radionuclide metrology based on the meta-analysis of its machine-readable database
Authors: Coulon Romain , Michotte Carine , Gressier Vincent
Published: November 2023

In support of the CIPM MRA, the reference system in radionuclide metrology (SIR) is a unique experimental facility that has been able to provide continuous key comparison results for 72 radionuclides for 46 years. These measurement data are now available in a machine-readable format, which allows statistical analysis of these measurement results to be performed efficiently. Such a meta-analysis was conducted to verify whether or not the accumulated data confirmed the bold assumption made in the 1970s of the long-term robustness of the system over decades of operation. It was notably assumed that variation in the properties of the standard solution to be measured or the choice of the 226Ra reference source would have no impact on the measurement. For the majority of radionuclides measured by the SIR, the non-parametric significance tests of the null hypothesis carried out in this study gave no evidence, at the 95% confidence level, that the above statement should be reconsidered. However, this meta-analysis revealed a significant impact of solution density in the case of 109Cd, corroborating previous observations made in the case of 241Am where the robustness of an ionization chamber with respect to the density variation of the solution does not appear to be perfect. The extension of the SIR by a liquid scintillation system is under development. It will improve the robustness of international comparison results for those borderline cases where radionuclides emit only low-energy x-rays or gamma rays (<100 keV).
Interaction between COLREG-compliant collision avoidance systems in a multiple MASS scenario
Authors: Zaccone R , Martelli M
Published: November 2023

The transportation systems are heading towards increasing autonomy in all domains, and the maritime field makes no exception. The International Maritime Organization has been working on releasing a regulatory framework for Maritime Autonomous Surface Ships (MASS) to keep pace with the technological developments in the field. Autonomous shipping forces the researcher and the designers to face a wide range of scientific challenges, such as navigation decision support systems, collision avoidance algorithms, path planning, navigation and control, sensor data processing and fusion, remote control, and communication, with the final intent of achieving a fully integrated and autonomous worldwide maritime transportation system, where a human-less collaborative conflict resolution could potentially retire the COLREGs. However, the maritime sector will first face a transition period where traditional ships will share the seas and interact with heterogeneous MASS with various autonomous capabilities featuring different and probably incompatible communication protocols. In such a scenario, the COLREGs will still play a primary role in helping the collision avoidance systems resolve conflicts and limiting the degrees of freedom. This paper aims to study the interaction among multiple vessels with autonomous collision avoidance capabilities operating in a close navigation scenario. The ships operate according to a COLREG-compliant collision avoidance algorithm. The paper relies on numerical simulation to systematically investigate different scenarios in which autonomous vessels operate and interact in the presence of fixed obstacles. Results are presented and critically discussed.
Gorillas on a boat: Inattentional blindness during supervisory control of autonomous vessels
Authors: Veitch Erik , Alsos Ole Andreas
Published: November 2023

When focused on a task, unexpected visual stimuli can go by unnoticed. Inattentional blindness may be problematic for supervisory controllers of autonomous vessels, because this role specifically relies on identifying unexpected stimuli in case intervention is needed. In a simulation-based experiment (n=32), we show that 50% of participants did not perceive an unexpected visual stimulus (a gorilla passenger) when assigned the task of supervisory controller for an autonomous ferry. Additionally, eye-tracking showed that 12 of the 16 players who did not report the gorilla in fact gazed directly at it. Results also showed no correlation to skillset (gamer or navigator) nor to vigilance (5- or 30-minute scenarios); they did, however, show positive correlation to multitasking (1 or 3 supervised vessels). We discuss implications for designing work tasks for supervisory control of remotely operated and autonomous vessels.
Rotor and wake aerodynamic analysis of the Hybrid-Lambda concept - an offshore low-specific-rating rotor concept
Authors: Ribnitzky Daniel , Bortolotti Pietro , Branlard Emmanuel , Kühn Martin
Published: November 2023

The low-specific-rating rotor concept Hybrid-Lambda introduces a blade design with nonuniform distribution of design variables (design tip speed ratio and axial induction) along the blade span to alleviate loads of the outboard section in strong winds. In this paper, we validate aerodynamic design calculations, which were carried out with the blade element momentum theory by comparing the results to free vortex wake investigations (FVW). Furthermore, we investigate the wake behaviour with FVW and large-eddy simulations. The results show good agreements between the blade element momentum theory and FVW for integrated rotor quantities (power and thrust). Small deviations are present when the gradients of axial induction along the span are large. The wake of the Hybrid-Lambda Rotor shows advantages in the near-wake region (up to 4 diameters [D] downstream), especially in the outer wake annulus and in low turbulence scenarios. For further downstream positions, the wake is comparable to that of the reference turbine.
Design and Simulation study of 40 MW PM Generator for the CRAFT
Authors: Simonsson Izabella , Eriksson Sandra , Bernhoff Hans
Published: November 2023

Design studies of two counter rotating permanent magnet (PM) synchronous generators have been performed. The two 40 MW generators have been designed and compared for the Counter Rotating Axis Floating Turbine (CRAFT) with different air-gap diameters. The generators are modelled with validated full physics finite element method (FEM) which also includes dynamic simulations. The simulations are performed by using an electromagnetic model. The model is described by combined field and circuit equations and is solved in a finite element environment. The stator winding of the generators consists of circular cables and the rotor consists of buried ferrite PM. The generator with smaller air-gap diameter will have lower material costs due to smaller frame but higher due to use of more active materials. A comparison of the counter rotating generators with a traditional direct drive has also been performed by maintaining the same voltage but reducing the rotational speed by half. This shows that a generator with a higher rotational speed will have lower material costs due to smaller dimensions and lower weight. Furthermore, a design variation, to reduce the cogging and harmonic content of the voltage by changing the pole shoe, was analyzed. In conclusions, a 40 MW generator design for the CRAFT has successfully been simulated with a multi-physics-FEM. The advantages of using a counter-rotating generator has been established.
Technical modeling challenges for large idling wind turbines
Authors: Bangga Galih , Carrion Marina , Collier William , Parkinson Steven
Published: November 2023

This paper presents comprehensive investigations into idling instability occurring on the IEA 15 MW reference turbine. The systematic studies are carried out by means of Blade Element Momentum (BEM) and free wake vortex (Vortexline) methods. Two state-of-the-art dynamic stall models are tested in the present investigations, namely the Beddoes-Leishman and the IAG dynamic stall models, implemented into a development version of the wind turbine design code Bladed. The studies highlight the importance of unsteady aerodynamic modeling to predict idling instabilities and emphasize the characteristics of each modeling strategy. It is demonstrated that the IAG dynamic stall model predicts a more physically reasonable idling instabilities. Furthermore, Vortexline enables the calculations of the induced velocities even under idling conditions in contrast to BEM. The combination of the Vortexline method and the IAG model is considered to provide the most reasonable turbine response. The studies will be helpful for load engineers to select appropriate modeling strategies and shed some light into future engineering modeling improvements of wind turbines.
Nonlinear modelling of shared mooring concepts for floating offshore wind turbines
Authors: Pan Qi , Guo Feng , Lüdecke Fiona D.
Published: November 2023

Shared mooring has been proposed as one of the innovative technologies to reduce mooring and anchoring expenses for floating offshore wind turbines (FOWTs). Despite cost saving benefits, shared moorings introduce more complexity for the connected FOWTs than the conventional moorings. In this paper, we propose a nonlinear modelling approach for mooring configurations in Simpack and investigate the impact of a shared line mooring configuration on floater motions and mooring tensions of two connected FOWTs. First, we validate the nonlinear mooring modelling method through a comparison between OpenFAST and Simpack simulations of a 15-MW semi-submersible FOWT. Second, two 15-MW FOWTs with a shared mooring line configuration are further analyzed in Simpack to investigate the shared mooring impact. Different performances of the wind-wave loaded and unloaded FOWTs in two cases reflects the importance of considering nonlinear mooring stiffness in the modelling approach. By comparing the simulation results of two FOWTs using shared moorings and the single FOWT using conventional moorings, we identify the challenges of applying a shared mooring configuration that the surge displacements of the connected FOWTs increase significantly.
Efficient Mann turbulence generation for offshore wind farms with applications in fatigue load surrogate modelling
Authors: Liew Jaime , Riva Riccardo , Göçmen Tuhfe
Published: November 2023

Surrogate models are vital for offshore wind farm optimisation, or digital twin for rapid execution. Reliable surrogates are difficult to make, especially for large wind farms and for fatigue loads. One limitation is the high resolution of turbulence needed for fatigue calculations and the vast size of a wind farm. We present code optimisations for implementing the Mann model for farm-sized flows, which are infeasible otherwise. Additionally, we present a case study of a full load surrogate for the Lillgrund offshore wind farm using large turbulence box generation in aeroelastic wind farm simulations using HAWC2Farm. Various mappings between the wind field in front of a turbine and the corresponding turbine structural fatigue loads are presented. The best-performing surrogate model, using a proper orthogonal decomposition of the input space with an artificial neural network, is able to significantly reduce the error in fatigue load estimates by as much as a factor of 5 compared to conventional methods. The presented recommendations are crucial to generating reliable wind farm load surrogates for wind farm optimisation purposes.
Comparative assessment of actuator-Line modeling of FOWT rotor aerodynamics to wind tunnel experiments
Authors: Sanvito Andrea G , Persico Giacomo , Schito Paolo , Dossena Vincenzo , Zasso Alberto
Published: November 2023

The paper presents aerodynamic analyses of the scaled DTU 10MW laboratory model with surge and pitch platform motion in controlled environment applying an Actuator Line Method (ALM) to reproduce the experiments conducted in the large-scale Wind Tunnel of the Politecnico di Milano during UNAFLOW and OC6 Phase III test campaigns. The Effective Velocity Method (EVM) is implemented in the in-house ALM solver to sample the velocity at actuator points and determine the angle of attack. Fixed-bottom wind turbine URANS simulations reveal that thrust and torque deviations are within 3% and 5% respectively to experimental counterparts. Platform surge and pitch are simulated with ALM adopting a combination of motion frequencies and amplitudes finding a good agreement with experimental counterparts both in terms of loads and wake quantities. This paper also shows the capability of in-house ALM to model control strategies, imposing sinusoidal variation of blade collective pitch, which might generate dynamic inflow conditions. An in-depth cross comparison is conducted on FOWT wake quantities to investigate the flow behaviour and wake recovery induced by floating motion.
Towards a comprehensive understanding and assessment of Offshore Energy Hubs with a hydrogen focus: An evolutionary perspective
Authors: Petersen M , Andreae E , You S , Mortensen H B
Published: November 2023

Climate change has necessitated the reduction of CO2 emissions, particularly in hard-to-abate sectors. Offshore Energy Hubs (OEHs), powered by renewable sources, have been proposed as a potential solution for renewable build-out and cross-sectoral integration. This paper presents a comprehensive literature review examining the technical concept and assessment mechanisms of OEHs from multiple perspectives, including chronological, design, and assessment principles. The review reveals a shift in the technical concept and evaluation assessments, evolving from cost-driven to economically driven, with a trend towards harmonized assessments that incorporate both economic and societal values, such as environmental impact. The importance of societal assessments is emphasized, addressing a research gap, where further investigation is needed for a successful implementation of future large-scale OEH projects. The paper highlights the need to develop comprehensive and inclusive evaluation frameworks to ensure the sustainable implementation of OEHs for the ongoing energy transition.
Mitigation measures for preventing collision of birds with wind turbines
Authors: Garcia-Rosa Paula B. , Tande John Olav G.
Published: November 2023

Bird collisions with wind turbines is one of the major environmental impacts of wind energy. To decrease the number of avian fatalities in wind farms, several studies have been done to understand, evaluate and apply measures that reduce the risks of collisions. Overall, mitigation measures during the operational phase of wind farms are based on either active or passive procedures, depending on the need (or not) for an external source to trigger an action for preventing a possible collision. The aim of this work is firstly to provide an overview of mitigation measures that have been demonstrated in-situ, including the overall procedures of the tests, results, as well as advantages and disadvantages of the measures. Subsequently, a new patented control concept to avoid collisions (SKARV) is described. Four measures that have been tested at wind farms in Spain, Norway, and USA are summarized: habitat management and painting (passive measures), turbine curtailment and deterrents (active measures). Estimations from these tests indicate an average reduction of 33%-86% in annual bird fatality for specific targeted species. The SKARV concept is not yet tested, but may be a benign alternative.
The linear regression model to evaluate material moisture using reflectometric technique
Authors: Jastrzębska M , Futa A , Suchorab Z
Published: November 2023

The paper presents the linear regression model of moisture detection technique in the building material (clinker brick). In particular, the assumptions of linear regression model, which play very important role, are emphasized. The obtained data present the dependence between the moisture of clinker brick, evaluated gravimetrically and permittivity values determined by TDR technique. Using the achieved data, the optimal regression model is obtained and the advantages of applying the linear regression model are discussed.
Viability of yeasts after exposure to flax-fiber based composite materials
Authors: Kobetičová K , Nábělková J , Brejcha V , Brich J , Böhm M , Černý R
Published: November 2023

In the present study, the prepared bio-composite materials based on flax fibers containing caffeine or nano-copper (Cu) or corundum (Al2O3) as a potential biocidal substance were prepared and tested on their toxicity. Two viability tests were performed. Firstly, the screening test based on colouring by Methyl-blue was applied on yeast cells of strain Saccharomyces cerevisae. The number of cells density was observed under microscope and Methyl-blue was then added. Part of the cells coloured in blue and it indicated their death. For this reason, MTT viability assay was performed. The method is based on production of blue product formazan by yeasts after their metabolization of added initial substrate, 3-[4,5-dimethylthiazol-2-yl]-2,5-difenyltetrazolium bromide. The intensity of blue-coloured formazan was measured spectrophotometrically at 485 nm. The results indicated that the inhibition of yeasts was increased in the following rate: cu-samples (14-16 %) < flax sample without biocidal substances (21%) = pure flax (23 %) < caffeine-samples (up to 29 %) < corundum-samples (up to 35 %).
Some problems related to thermophysical properties of selected barrel steels
Authors: Koniorczyk P , Zielinski M
Published: November 2023

The paper discusses selected issues related to the thermophysical properties of selected barrel steels, which the authors have been dealing with over the last few years, i.e. 38HMJ (1.8509), 30HN2MFA, X37CrMoV5-l hot-work tool steel (1.2343), DUPLEX (1.4462) and MARAGING 350 (1.6355). In some of them, i.e. in the X37CrMoV5-1 hot work tool steel, 38HMJ, 30HN2MFA, a ferrite-austenite phase transition occurs, which causes shrinkage of the material. During a series of shots, multiple shrinkage of material degrades the barrel channel and deteriorates the ballistic parameters of the cannon barrel. Another problem concerns the apparent specific heat that we get from the DSC measurement and the dependence of the specific heat on temperature in the form that we use for the numerical simulations. The point is that the phase transition effect should not be taken into account twice, i.e. in the thermal diffusivity characteristics and in the specific heat characteristics. For all selected steels the thermophysical properties, i.e. thermal diffusivity, thermal conductivity, specific heat and thermal expansion, were obtained in a wide range of temperature, so they can be used as input data for numerical simulations.
Moisture transport in loose fibrous insulations subjected to air filtration
Authors: Kosiński Piotr , Startek Adam
Published: November 2023

Fibrous insulations are susceptible to air filtration, which affects both heat loss and moisture transport in the materials. Each fibrous material has individual heat and mass transfer characteristics. This is due to the structure of the fibers, their connections, and their density. The authors performed tests of the air permeability of loose mineral wool and wood wool of different densities and moisture content levels. We are presenting a comparison of materials, and their transport characteristics depending on density and moisture content. Convective moisture flow caused by air filtration is different for mineral and wood wool. The difference in the form of accumulation of sorption moisture in the material affects its redistribution due to the flow of air.
Deconvolution of DSC peaks of high-temperature phases in an illite/smectite–CaCO3 mixture
Authors: Medved I , Kuruc M , Kovács T , Trník A
Published: November 2023

Heat flow curves measured in differential scanning calorimetry (DSC) may contain overlapping peaks corresponding to multiple-step processes. To analyze the individual steps in such a process, a deconvolution of the overlapping peaks into the individual peaks is necessary. Using the Frazer-Suzuki function to describe asymmetric peaks, we apply a nonlinear least squares analysis to perform the decomposition of heat flow curves measured for a mixture of an illite/smectite clay with 19.6 wt.% of CaCO3. The curves contain two overlapping peaks associated with the crystallizations of gehlenite and anorthite in the temperature interval from 900 °C to 1050 °C. Several versions of the decomposition analysis may be used, depending on the number of optimized parameters. These may range from four to all eight parameters (four for either peak). We applied the versions with seven and eight fitting parameters, yielding results that are in very good agreement with the experimental data.
Analysis of indoor air parameters in the occupied zone
Authors: Szekeres S
Published: November 2023

Since the COVID-19 pandemic, the number of occupants in many office buildings has decreased around the world, but the comfort parameters in the buildings had to be maintained. Various measures have been taken by the facilities to ensure that the people in the buildings are as protected and safe as possible. Put plexiglass sheets on the desks between the people as a physical barrier and arranged the desks to manage to keep a distance from each other. As a result of these measures, the existing air ventilation system may not be able to provide the designed condition. Analysis of the fresh air ratio was carried out with two different desk arrangements and examined the effect of barriers. As the HVAC systems contribute significantly towards the final energy consumption by buildings it is important to minimalize the level of ventilation. This study focused on the air volume flow, and the mean air velocity. Furthermore investigated the turbulence intensity in percentage as well as the drought rate and comfort levels according to standards. After analyzing the measurement results, various proposals for action have been established.
An abundant future for quagga mussels in deep European lakes
Authors: Kraemer Benjamin M , Boudet Salomé , Burlakova Lyubov E , Haltiner Linda , Ibelings Bas W , Karatayev Alexander Y , Karatayev Vadim A , Rossbacher Silvan , Stöckli Raphael , Straile Dietmar , Spaak Piet
Published: November 2023

Quagga mussels have expanded their range across the northern hemisphere in recent decades owing to their dispersal abilities, prolific reproduction rates, and broad ecological tolerances. Their remarkable capacity to filter particulates from the water column has had profound effects on inland aquatic ecosystems. In the North American Great Lakes, quagga mussel populations have increased inexorably since the late 1980’s, but it remains unclear whether quagga mussels will follow a similar trajectory in Europe where they have appeared more recently. Here we apply knowledge from a long-term quagga population monitoring effort in the North American lakes to predict future quagga populations in deep European lakes, where quaggas are quickly becoming a conspicuous part of the underwater landscape. We predict that quagga mussel biomass in Lakes Biel, Constance, and Geneva may increase by a factor of 9–20 by 2045. Like in North America, this increase may be characterized by a shift to larger individuals and deeper depths as the population matures. If realized, this rapid expansion of quagga mussels would likely drive the largest aquatic ecosystem change in deep European lakes since the eutrophication period of the mid-20th century.
Optimal entanglement generation in GHZ-type states
Authors: Giovenale N , Hernandez-Martinez L , Majtey A P , Valdés-Hernández A
Published: November 2023

The entanglement production is key for many applications in the realm of quantum information, but so is the identification of processes that allow to create entanglement in a fast and sustained way. Most of the advances in this direction have been circumscribed to bipartite systems only, and the rate of entanglement in multipartite system has been much less explored. Here we contribute to the identification of processes that favor the fastest and sustained generation of tripartite entanglement in a class of 3-qubit GHZ-type states. By considering a three-party interaction Hamiltonian, we analyze the dynamics of the 3-tangle and the entanglement rate to identify the optimal local operations that supplement the Hamiltonian evolution in order to speed-up the generation of three-way entanglement, and to prevent its decay below a predetermined threshold value. The appropriate local operation that maximizes the speed at which a highly-entangled state is reached has the advantage of requiring access to only one of the qubits, yet depends on the actual state of the system. Other universal (state-independent) local operations are found that conform schemes to maintain a sufficiently high amount of 3-tangle. Our results expand our understanding of entanglement rates to multipartite systems, and offer guidance regarding the strategies that improve the efficiency in various quantum information processing tasks.
Investigating Airflow Patterns in the XYZ Passenger Ship’s Accommodation Room on the Potential for COVID-19 Exposure to Passengers
Authors: Ariani Betty , Febriyan  , Sholahudin Dimas , Ardan Nagra C , Oktaviani Marista , Hakim M.Hanifuddin
Published: November 2023

The pandemic condition due to the COVID-19 virus attack has affected all areas of life throughout the earth. Post-pandemic policies and new behaviors are one of the important efforts in getting life back to normal. The pandemic has triggered many technological innovations to be carried out as further mitigation and prevention efforts. In the shipping sector, the impact of shipping restrictions and the number of passengers is detrimental due to a decrease in productivity that affects the shipping and port business. Air exchange patterns and room design are important things to be conditioned to reduce the potential for virus exposure. This article presents an investigation of computational fluid dynamics in the accommodation space of the XYZ passenger ship and simulations of potential exposures in several scenarios of ventilation conditions. By simulating 12 models of ventilation conditions, two conditions of the ships being stationary and moving, and the influence of wind from outside. Layout redesign can be applied effectively in open ventilation conditions and has less exposed bench results compared to existing conditions with an effective percentage of 0.75% - 2.3%
Potassium and calcium content in padelegan water which is used as the raw water for making salt
Authors: Kartika Ary Giri Dwi , Septian Haris , Nuzula Nike Ika , Pratiwi Wiwit Sri Werdi
Published: November 2023

Potassium and calcium are elements contained in seawater. The presence of potassium and calcium in raw saltwater were impurities in producing non-food salt. On the other hand, potassium and calcium as target minerals are desirable in mineral-rich healthy salt (food salt) production. Information about the potassium and calcium content in raw salt water can assist in analyzing the quality of the salt to be produced. The purposes of this study were; to determine the content of potassium, and calcium in Padelegan waters used as a source of salt raw materials, compare them with other locations, and their correlation with water quality. The potassium and calcium content in the sample were determine used the AAS (Atomic Absorption Spectrophotometry) method. Potassium concentrations ranged from 221,870 to 285,110 mg/L, and those for calcium from 497,700 to 552,713 mg/L. The potassium content in Padelegan waters is smallest than other reference waters. In contrast, the calcium content in Padelegan waters is greatest than in other reference waters.