bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining Rankine–Hugoniot relations, ion dynamics in the shock front, and the cross-shock potential
Authors: Gedalin M.
Published: November 2022

Rankine–Hugoniot relations (RH) connect the upstream and downstream plasma states. They allow us to determine the magnetic compression, the density compression, and the plasma heating as functions of the Mach number, shock angle, and upstream temperature. RH are based on the conservation laws in the hydrodynamical form. In collisionless shocks, the ion distributions behind the shock transition are determined by ion dynamics in the macroscopic fields of the shock front. The ion parameters upon crossing the shock are directly related to the magnetic compression and the cross-shock potential. For given upstream parameters, RH provide the magnetic compression. If there is no substantial overshoot, an analytical estimate provides the cross-shock potential as a function of the magnetic compression and the Mach number. Numerical tracing of ions across a shock profile with the derived parameters provides the ion pressure, which is in good agreement with the combination of the two theoretical approaches.
Atoms and bonds in molecules as synergisms of interactions between electrons and nuclei
Authors: Ruedenberg Klaus
Published: November 2022

The molecular electronic wave functions are expressed in quasi-atomic form. The corresponding global energy expression exhibits the unified resolution of the various modes of chemical bonding in terms of physical interactions. The bonding patterns in several molecules is elucidated.
High electron mobility in AlN:Si by point and extended defect management
Authors: Bagheri Pegah , Quiñones-Garcia Cristyan , Khachariya Dolar , Rathkanthiwar Shashwat , Reddy Pramod , Kirste Ronny , Mita Seiji , Tweedie James , Collazo Ramón , Sitar Zlatko
Published: November 2022

High room temperature n-type mobility, exceeding 300 cm2/Vs, was demonstrated in Si-doped AlN. Dislocations and CN−1 were identified as the main compensators for AlN grown on sapphire and AlN single crystalline substrates, respectively, limiting the lower doping limit and mobility. Once the dislocation density was reduced by the growth on AlN wafers, C-related compensation could be reduced by controlling the process supersaturation and Fermi level during growth. While the growth on sapphire substrates supported only high doping ([Si] > 5 × 1018 cm−3) and low mobility (∼20 cm2/Vs), growth on AlN with proper compensation management enabled controlled doping at two orders of magnitude lower dopant concentrations. This work is of crucial technological importance because it enables the growth of drift layers for AlN-based power devices.
Fluid force, moment, and torque measurements of oscillating prism and cylinder using loadcell
Authors: Alam Md. Mahbub
Published: November 2022

Vortex-induced and galloping vibrations both are the consequence of fluid–structure coupling. Measurements of fluid loads are crucial for an understanding of the insight into flow-induced vibrations. This paper presents a systematic theory of how to estimate fluid loads (forces, moment, and torque) on a cantilevered prism and a cantilevered cylinder undergoing flow-induced oscillation. When a loadcell measuring fluid loads is mounted at the fixed end of the cantilevered prism or cylinder, the output of the loadcell captures both inertial and fluid loads. To correctly estimate the fluid loads on the oscillating prism or cylinder, the inertial loads on the prism or cylinder have to be subtracted from the loadcell output. Here, we develop equations and present a way to estimate inertial forces, inertial moments, and inertial torques for different oscillation shape functions and modes. The present systematic analysis of estimating inertial and fluid loads would be handy for undergraduate and postgraduate students, researchers, and engineers.
Numerical simulation of electrokinetic control of miscible viscous fingering
Authors: Nwani B. N. , Merhaben C. , Gates I. D. , Benneker A. M.
Published: November 2022

Active control of viscous fingering (VF) is of critical importance for many industrial and experimental systems. Here, we numerically study the electrokinetic control of miscible VF using an externally applied electric field. Simulations for three intrinsically hydrodynamically unstable mobility ratios are carried out using two different configurations for each: case I where the high-viscosity resident fluid has higher electroosmotic mobility than the invading low-viscosity fluid and case II where the resident fluid has a lower electroosmotic mobility than the invading fluid. For both cases, the theoretical critical electric field value required to (de)-stabilize the interface is computed and electric fields around this value are applied in simulations. Qualitative results show that VF can be fully suppressed if an electric field is applied with an absolute value above the critical field strength. For case I, this means an electric field in the direction of the pressure-driven flow, while for case II, a field in opposite direction is required. Our quantitative analysis using interfacial and mixing lengths was used to support the qualitative findings. Even though any field strength applied in the right direction will reduce the instability, full suppression is only achieved if the absolute field strength is higher than the required critical field strength. The results from this work provide useful insights that can be applied to electrokinetically enhanced oil recovery, spreading of pollution zones in aquifers, band broadening in liquid chromatography, and electrokinetic soil remediation.
Two-layer two-phase material point method simulation of granular landslides and generated tsunami waves
Authors: Zhao Kai-Li , Qiu Liu-Chao , Liu Yi
Published: November 2022

Numerical modeling of the entire process of tsunamis generation by granular landslides is very difficult and challenging as it involves the soil–water interaction, large deformation of soil, and the fluidization and sedimentation of sand. In this study, a computational model based on the two-layer two-phase material point method (MPM) is developed to simulate granular-landslide-generated tsunamis, wherein the soil–water interaction, large deformation of soil, and fluidization and sedimentation of sand are well modeled. The soil behavior is described using a Mohr–Coulomb model with a non-associated flow rule, while the water is considered as weakly compressible. Furthermore, three different benchmark problems are simulated. All computed results well agree with the corresponding analytical solution and laboratory test data, verifying the effectiveness of the proposed two-layer two-phase MPM for modeling the subaerial and submerged granular-landslide-generated tsunamis. Additionally, the influence of different soil material parameters on the water wave generated by the subaerial granular landslide is investigated.
The β-cell primary cilium is an autonomous Ca2+ compartment for paracrine GABA signaling
Authors: Sanchez Gonzalo Manuel , Incedal Tugce Ceren , Prada Juan , O’Callaghan Paul , Dyachok Oleg , Echeverry Santiago , Dumral Özge , Nguyen Phuoc My , Xie Beichen , Barg Sebastian , Kreuger Johan , Dandekar Thomas , Idevall-Hagren Olof
Published: November 2022

The primary cilium is an organelle present in most adult mammalian cells that is considered as an antenna for sensing the local microenvironment. Here, we use intact mouse pancreatic islets of Langerhans to investigate signaling properties of the primary cilium in insulin-secreting β-cells. We find that GABAB1 receptors are strongly enriched at the base of the cilium, but are mobilized to more distal locations upon agonist binding. Using cilia-targeted Ca2+ indicators, we find that activation of GABAB1 receptors induces selective Ca2+ influx into primary cilia through a mechanism that requires voltage-dependent Ca2+ channel activation. Islet β-cells utilize cytosolic Ca2+ increases as the main trigger for insulin secretion, yet we find that increases in cytosolic Ca2+ fail to propagate into the cilium, and that this isolation is largely due to enhanced Ca2+ extrusion in the cilium. Our work reveals local GABA action on primary cilia that involves Ca2+ influx and depends on restricted Ca2+ diffusion between the cilium and cytosol.
Activating NO–sGC crosstalk in the mouse vascular niche promotes vascular integrity and mitigates acute lung injury
Authors: He Hao , Yang Wu , Su Nan , Zhang Chuankai , Dai Jianing , Han Feng , Singhal Mahak , Bai Wenjuan , Zhu Xiaolan , Zhu Jing , Liu Zhen , Xia Wencheng , Liu Xiaoting , Zhang Chonghe , Jiang Kai , Huang Wenhui , Chen Dan , Wang Zhaoyin , He Xueyang , Kirchhoff Frank , Li Zhenyu , Liu Cong , Huan Jingning , Wang Xiaohong , Wei Wu , Wang Jing , Augustin Hellmut G. , Hu Junhao
Published: November 2022

Disruption of endothelial cell (ECs) and pericytes interactions results in vascular leakage in acute lung injury (ALI). However, molecular signals mediating EC–pericyte crosstalk have not been systemically investigated, and whether targeting such crosstalk could be adopted to combat ALI remains elusive. Using comparative genome-wide EC–pericyte crosstalk analysis of healthy and LPS-challenged lungs, we discovered that crosstalk between endothelial nitric oxide and pericyte soluble guanylate cyclase (NO–sGC) is impaired in ALI. Indeed, stimulating the NO–sGC pathway promotes vascular integrity and reduces lung edema and inflammation-induced lung injury, while pericyte-specific sGC knockout abolishes this protective effect. Mechanistically, sGC activation suppresses cytoskeleton rearrangement in pericytes through inhibiting VASP-dependent F-actin formation and MRTFA/SRF-dependent de novo synthesis of genes associated with cytoskeleton rearrangement, thereby leading to the stabilization of EC–pericyte interactions. Collectively, our data demonstrate that impaired NO–sGC crosstalk in the vascular niche results in elevated vascular permeability, and pharmacological activation of this crosstalk represents a promising translational therapy for ALI.
Discriminating an Accent, Enacting a Race (and Vice Versa): Perception and Representation of Phonic Variability on the Caribbean Coast of Colombia
Authors: Blestel Élodie
Published: November 2022

We examine the metalinguistic, psychosocial, and identity-related indexical indications of (speaking about) the other, as provided by 36 Santa Marta inhabitants (Blestel 2022). Santa Marta is a city on Colombia’s septentrional coast, populated primarily by individuals of multiracial heritage, descended from Indigenous peoples, African slaves, and Spaniards. We show that the established main axis of differentiation (Gal and Irvine 2019) and associated judgments are adjacent, sometimes very explicitly, to racializing ideologies that more broadly traverse Colombian society as a whole. We maintain that these metapragmatic discourses, far from being anecdotal, indicate semiotic discrimination processes at work in sustaining or even renewing a system of values passed down from the colonial era.
Neck-embedded acoustic meta-liner for the broadband sound-absorbing under the grazing flow with a wide speed range
Authors: Zhao Jiang , Wu Fei , Ju Ze-Gang , Hu Man , Zhang Xiao , Li Dan , Yan Shan-Lin , Liu Ke-Ling
Published: November 2022

Acoustic liners are the most commonly used dissipative muffler for aero-engines but remain a challenge to design a broadband acoustic liner under the grazing flow. In this work, a novel neck-embedded meta-liner is proposed for the broadband sound-absorbing under the grazing flow with a wide speed range. The meta-liner is composed of many neck-embedded Helmholtz Resonators, and the idea of bending the subsequent cavity is introduced to improve low-frequency sound absorption performance. The acoustic impedance model of the meta-liner with neck-embedded slit is first detailly established by analyzing the acoustic characteristics of the equivalent elliptical pipe and using the matrix transfer method. Then by designing the local coupling between channels, efficient broadband impedance modulation and broadband matching with air impedance under grazing flow conditions are realized. The proposed meta-liner exhibits the excellent sound attenuation capacity in the frequency domain of 500–3000 Hz under the grazing flow speeds from 0 m s−1 to 98 m s−1 and the sound absorption performance is greatly boosted compared with the traditional Double- Degree-Of-Freedom liner. Features mentioned above have been verified numerically and in a series of comparative experiments. Besides, the thickness of the meta-liner is only 50 mm. Our work provides a possible design reference for the new generation of acoustic liners and has potential applications in noise reduction engineering.
Broadband flattened underwater acoustic Luneburg lens
Authors: Tong Shuaishuai , Ren Chunyu , Tao Jun , Jiang Lixun
Published: November 2022

Conventional Luneburg lenses are symmetric circular gradient-index lens with no aberration, but they are restricted by their circular focal surface. Here, we show the design, realization and measurement of an underwater acoustic Luneburg lens with flattened focal surface. The flattened lens is designed by using the quasi-conformal transformation technique and constructed by metamaterials based on air-filled photosensitive resin. Through numerical simulations and experimental studies, the flattened lens is demonstrated to have excellent focusing performance for the incident plane waves propagating at desired angles over a broad frequency band from 20 kHz to 35 kHz. The proposed flattened Luneburg lens can be potentially applied in the applications such as biomedical imaging, underwater acoustic sensing and communication.
Interfacial charge transfer induced antiferromagnetic metals and magnetic phase transition in (CrO2)
m
/(TaO2)
n
superlattices
Authors: Shan Wanfei , Luo Weidong
Published: November 2022

As a class of remarkable spintronic materials, intrinsic antiferromagnetic (AFM) metals are rare. The exploration and investigation of AFM metals are still in its infancy. Based on first-principles calculations, the interface-induced magnetic phenomena in the (CrO2)
m
/(TaO2)
n
superlattices are investigated, and a new series of AFM metals is predicted. Under different ratios of

m
:
n

with varying valence states of Cr, the (CrO2)
m
/(TaO2)
n
superlattices exhibit three different phases, including the AFM metal, the AFM semiconductor, and the ferromagnetic (FM) metal. In the AFM semiconducting phases, the intra-CrO2-monolayer magnetic exchange interaction is systematically discussed, corresponding to m = 1 or m = 2. Both the localization of the Cr 3 d orbitals and the crystal-field splitting are crucial for magnetic ordering in super-exchange interactions. Based on the analyses of the AFM semiconducting phases with m = 1 and m = 2, the mechanisms of AFM metallic phases with radios of

m
:
n
<
1

/

2

and

1

/

2
<
m
:
n
<
1

/

1

are discussed in detail. Additionally, the AFM metallic superlattices can be tuned into a FM metallic phase by applying strain in the c-direction, such as a compression of 7% in the (CrO2)1/(TaO2)3 superlattice, and a tensile strain of 7% in the (CrO2)2/(TaO2)3 superlattice. The phase diagram of the (CrO2)
m
/(TaO2)
n
superlattices is obtained as a function of the layer thickness. This work provides new insights about realizing and manipulating AFM metals in artificial superlattices or heterostructures in experiments.
Quasi-continuous dc voltage standard using sinusoidal and pulse-driven Josephson junction arrays
Authors: Georgakopoulos Dimitrios , Budovsky Ilya , Benz Samuel P
Published: November 2022

Josephson voltage standards (JVSs) provide a primary realization of the volt, the unit of electromotive force. They generate direct current (dc) voltages up to 10 V and show agreement better than 1 nV V−1 at 10 V. For JVSs based on Josephson junction arrays (JJAs) that are driven by sinusoidal radiofrequency (RF) power, commonly referred to as continuous wave-driven JJAs (CWD JJAs), the minimum voltage that can be generated is limited to the voltage across one Josephson junction (JJ) for practical devices. To achieve this resolution, they may require a perfect JJA chip. JVSs based on a pulse-driven (PD) JJA require high performance electronics (i.e. high bandwidth, low distortion and jitter, pulse shaping filters and large memory) to achieve their minimum and maximum voltage. We have combined two CWD JJAs and two PD JJAs driven by two microwave inputs to one chip to generate quasi-continuous dc voltages up to the sum of the full-scale voltages of both JJAs that are robust to the imperfections of the JJs and have relaxed requirements on the RF electronics driving the JJA, compared to the existing CWD JVSs and PD JVSs, respectively. By use of the JJA chip at the National Measurement Institute Australia, we demonstrate its feasibility to generate voltages up to 1 V. Preliminary evaluation of the system shows that the voltage uncertainty can be 11 nV (k = 2) or better and the theoretical resolution is better than 1 nV from 0 V to 1 V. The main requirement is that all the JJs must have quantum locking ranges with respect to the power and frequency of the RF bias and for the PD JJAs to have a constant voltage over a range of dc bias current. Although this development is not a replacement for existing state-of-the-art JVSs, we anticipate that it will be an alternative fit-for-purpose solution for metrological applications under non-ideal operating conditions or when the components of the state-of-the-art solutions are not available.
Diffraction imaging of light induced dynamics in xenon-doped helium nanodroplets
Authors: Langbehn B , Ovcharenko Y , Clark A , Coreno M , Cucini R , Demidovich A , Drabbels M , Finetti P , Di Fraia M , Giannessi L , Grazioli C , Iablonskyi D , LaForge A C , Nishiyama T , Oliver Álvarez de Lara V , Peltz C , Piseri P , Plekan O , Sander K , Ueda K , Fennel T , Prince K C , Stienkemeier F , Callegari C , Möller T , Rupp D
Published: November 2022

We explore the light induced dynamics in superfluid helium nanodroplets with wide-angle scattering in a pump–probe measurement scheme. The droplets are doped with xenon atoms to facilitate the ignition of a nanoplasma through irradiation with near-infrared laser pulses. After a variable time delay of up to 800 ps, we image the subsequent dynamics using intense extreme ultraviolet pulses from the FERMI free-electron laser. The recorded scattering images exhibit complex intensity fluctuations that are categorized based on their characteristic features. Systematic simulations of wide-angle diffraction patterns are performed, which can qualitatively explain the observed features by employing model shapes with both randomly distributed as well as structured, symmetric distortions. This points to a connection between the dynamics and the positions of the dopants in the droplets. In particular, the structured fluctuations might be governed by an underlying array of quantized vortices in the superfluid droplet as has been observed in previous small-angle diffraction experiments. Our results provide a basis for further investigations of dopant–droplet interactions and associated heating mechanisms.
Influence of charge on anisotropic class-one solution in non-minimally coupled gravity
Authors: Sharif M , Naseer Tayyab
Published: November 2022

This paper studies charged star models associated with anisotropic matter distribution in

f
(

,

,

)

theory, where


=



ϕ
ψ



ϕ
ψ

. For this purpose, we take a linear model of this gravity as


+
ζ


, where ζ represents a coupling constant. We consider a self-gravitating spherical geometry in the presence of electromagnetic field and generate solution to the modified field equations by using the ‘embedding class-one’ condition and

MIT

bag model equation of state. The observational data (masses and radii) of four different stellar models like 4U 1820-30, SAX J 1808.4-3658, SMC X-4 and Her X-I is employed to analyze the effects of charge on their physical properties. Finally, the effect of the coupling constant is checked on the viability, hydrostatic equilibrium condition and stability of the resulting solution. We conclude that the considered models show viable and stable behavior for all the considered values of charge and ζ.
Got plenty of nothing: cosmic voids as a probe of particle dark matter
Authors: Arcari S. , Pinetti E. , Fornengo N.
Published: November 2022

The search for a particle dark matter signal in terms of radiation produced by dark matter annihilation or decay has to cope with the extreme faintness of the predicted signal and the presence of masking astrophysical backgrounds. It has been shown that using the correlated information between the dark matter distribution in the Universe with the fluctuations of the cosmic radiation fields has the potential to allow setting apart a pure dark matter signal from astrophysical emissions, since spatial fluctuations in the radiation field due to astrophysical sources and dark matter emission have different features. The cross-correlation technique has been proposed and adopted for dark matter studies by looking at dark matter halos (overdensities). In this paper we extend the technique by focusing on the information on dark matter distribution offered by cosmic voids, and by looking specifically at the gamma-ray dark matter emission: we show that, while being underdense and therefore producing a reduced emission as compared to halos, nevertheless in voids the relative size of the cross-correlation signal due to decaying dark matter vs. astrophysical sources is significantly more favourable, producing signal-to-background ratios S/B (even significantly) larger than 1 for decay lifetimes up to 2 × 1030 s. This is at variance
with the case of halos, where S/B is typically (even much) smaller than 1. We show that forthcoming galaxy surveys such as Euclid combined with future generation gamma-ray detectors with improved specifications have the ability to provide a hint of such a signal with a predicted significance up to 5.7σ for galaxies and 1.6σ for the cosmic shear. The bound on the dark matter lifetime attainable exploiting voids is predicted to improve on current bounds in a mass range for the WIMP of 25 ÷ 900 GeV.
Identifying subdominant collective effects in a large motorway network
Authors: Wang Shanshan , Schreckenberg Michael , Guhr Thomas
Published: November 2022

In a motorway network, correlations between parts or, more precisely, between the sections of (different) motorways, are of considerable interest. Knowledge of flows and velocities on individual motorways is not sufficient, rather, their correlations determine or reflect, respectively, the functionality of and the dynamics on the network. These correlations are time-dependent as the dynamics on the network is highly non-stationary. Apart from the conceptual importance, correlations are also indispensable to detect risks of failure in a traffic network. Here, we proceed with revealing a certain hierarchy of correlations in traffic networks that is due to the presence and to the extent of collectivity. In a previous study, we focused on the collectivity motion present in the entire traffic network, i.e. the collectivity of the system as a whole. Here, we manage to subtract this dominant effect from the data and identify the subdominant collectivities which affect different, large parts of the traffic network. To this end, we employ a spectral analysis of the correlation matrix for the whole system. We thereby extract information from the virtual network induced by the correlations and map it on the true topology, i.e. on the real motorway network. The uncovered subdominant collectivities provide a new characterization of the traffic network. We carry out our study for the large motorway network of North Rhine-Westphalia, Germany.
Preliminary Sizing and Optimization of Semisubmersible Substructures for Future Generation Offshore Wind Turbines
Authors: Abdelmoteleb Serag-Eldin , Mendoza Alejandra S. Escalera , Santos Carlos R. dos , Bachynski-Polić Erin E. , Griffith D. Todd , Oggiano Luca
Published: November 2022

Several key development areas have been identified as having high potential for reducing the levelized cost of energy of offshore wind. Two of the most anticipated developments are future generation large wind turbines and the use of floating foundations. There is thus a need for developing large floating substructures that are capable of hosting future generation wind turbines. This work presents the preliminary sizing of two semi-submersible platforms for supporting a 25 MW turbine through a design space search using a simplified parametric analysis. Compared to simple theoretical upscaling, the substructures resulting from the proposed simplified parametric analysis have significantly lower steel mass and stiffer tower.
Mesoscale Simulation of Open Cellular Convection: Roles of Model Resolutions and Physics Parameterizations
Authors: Bui Hai , Bakhoday-Paskyabi Mostafa
Published: November 2022

The Open Cellular Convection (OCC) associated with cold air outbreaks is a common phenomenon over the North Sea where a large number of wind parks are presented. Thus, reliable numerical simulations of OCC events have great importance for offshore wind energy. We investigate the ability to simulate the OCC events using the Weather Research and Forecast (WRF) model with the ERA5 reanalysis data as initial and lateral boundary conditions and the OSITA data as the sea surface temperature. The domains were nested from 9 km as the outermost domain to 1 km as the innermost domain surrounding the Teesside wind farm located in the North Sea off the northeast coast of England. We simulated an OCC event in 2015 with three series of sensitivity numerical experiments of planetary boundary layer, microphysics, and radiation parameterizations. The model outputs were validated against the wind observation at the Teesside’s meteorological mast. The results suggest that the planetary boundary layer schemes are the most sensitive during the events compared to other parameterization schemes. Futher more, a convective-resolved resolution is necessary for simulating the OCC variation properly. The paper also discuss the verification methods for such short time-scale events like the OCC.
Impact of the wave/wind induced oscillations on the power performance of the WindFloat wind turbine
Authors: Couto A , Justino P. , Simões T , Estanqueiro A
Published: November 2022

The main objective of this work is the characterization of the wave/wind induced oscillations on the power performance of the wind turbine operating on a WindFloat floating system. To assess the potential impact on the wind turbine power performance induced by these oscillations, the nacelle movements of the WindFloat wind turbine were monitored using accelerometer sensors synchronized with : 1) metocean data measured with a buoy; 2) wind turbine power data installed in the WindFloat floating system; and 3) wind speed data gathered from a nacelle-mounted LiDAR. Based on this data, a clustering analysis approach is proposed. No meaningful relationship between the ocean parameters and the nacelle movements or the wind power production could be established. The obtained results suggest that the dynamic adaptation of the drive train (mainly due to wind turbine torque control) to a fast oscillating (primary energy) moving force is the source of the largest oscillations in the nacelle of the WindFloat wind turbine. Nevertheless, results suggest that the wind/wave induced oscillations and their impact on the power performance of the WindFloat wind turbine is low considering its nominal capacity. Outcomes of this work were extremely relevant to demonstrate the stability of the WindFloat system, and, consequently, also important for the development of the floating wind offshore industry (and other technologies).
Offshore grid topology optimisation with a geographical information system
Authors: Fliegner Felix Jakob
Published: November 2022

A novel methodology is investigated to identify and optimise large scale offshore grid topologies connecting multiple wind farms and countries with each other. A Geographical Information System (GIS) is setup to cluster wind farms and create a permissive graph topology. Its purpose is to propose grid layouts with potential hub locations and landing points bottom-up in a fully analytical toolchain, while avoiding manual scenario building. A coupled market model performs the investment optimisation into new lines on the GIS created graph. This two-step procedure is demonstrated at the example of the Baltic Sea Region for the target year 2040. It can be found, that future offshore topologies benefit from bundled transmission paths and many clustered wind farms. A sensitivity analysis reveals that the topology results are sensitive for wind farm location assumptions and pre-defined interconnectors or hubs. Not least, the capability of the onshore grid to integrate the influx of offshore wind power and the level of detail it is modelled in, directly reflects on the topology results for the offshore grid. It is concluded that optimising the future offshore grid is a quest of pan-European scale which benefits heavily from geo data based pre-processing in a GIS.
Modelling the loads and motions of a floating offshore wind turbine with asymmetric moorings
Authors: Formosa W , Sant T
Published: November 2022

Despite the improvements in wind energy conversion technology, wake effects present in wind farms still remain a challenge. In the case of floating offshore wind turbines (FOWTs), these can be mitigated by varying the mooring lengths to dynamically position the FOWTs according to the wind direction. As this introduces asymmetry in the mooring system, the stability of the FOWTs may be affected. With the aim of unlocking the full potential of floating offshore wind, this work investigates the loads and motions of a full-scale 6 MW spar-supported FOWT with four catenary moorings as its position is shifted along the crosswind direction. A hydrodynamic model developed in ANSYS® AQWA™ to obtain the dynamic response of the system in four metocean conditions is presented. Results indicate that asymmetry in the mooring system has a noticeable effect on the sway and roll motions as well as the cable tensions. The wave height and irregularity only appear to influence the FOWT motions. In general, the dynamic response of the FOWT system is not expected to be jeopardized as the typical permissible limits for a spar-supported FOWT and the proof load of the cables were not exceeded.
Estimating the major replacement rates in next-generation offshore wind turbines using structured expert elicitation.
Authors: Jenkins Brian , Belton Ian , Carroll James , McMillan David
Published: November 2022

With offshore wind turbines continuing to increase in size and move further offshore and into harsher environments, the complexity of carrying out the major replacement of large components is expected to pose a significant challenge for future offshore wind farms. However, the rate of major replacement operations that will be required in these next generation offshore wind turbines is currently unknown. Using a structured expert elicitation method, based on the Classical Model and implemented using EFSA guidance for the practical application of structured expert elicitation, major replacement rates of large components (generator, gearbox, and rotor) were systematically estimated for four next generation offshore wind turbine configurations, based on the knowledge of six wind energy experts. The results presented in this paper are based on an equal-weighting aggregation approach. The major replacement rate values found using this approach are presented and compared between different turbine configurations. Based on these results, it is expected that a larger number of major replacement operations are more likely to be required in medium-speed turbine configurations, in comparison to direct- drive, and in floating turbines, in comparison to fixed-foundation turbines.
Combined current and wind simulation for floating offshore wind turbines
Authors: Otter A , Desmond C , Flannery B , Murphy J
Published: November 2022

This paper describes the validation of a novel method to simulate current loading on a floating offshore wind turbine model. A dynamic winch actuator is used to emulate the drag force of current on the platform of the model with a Software in the Loop application. Current loads are combined with wave- and wind loads. The results of experiments with physical current are validated against the results of experiments with simulated current. A method to simulate wave-current interactions is also described. The results show that the winch actuator can reliably emulate current induced drag forces in comparison with physical current under various combinations of environmental loads. Experimental repeatability of the response of the platform is shown to be superior when using simulated- rather than physical current.
Wind-induced response of an offshore wind turbine under non-neutral conditions: A comparison with Hywind Scotland
Authors: Putri Rieska Mawarni , Obhrai Charlotte
Published: November 2022

In this study, aeroelastic simulations of a 5 MW spar wind turbine are performed by using simulated wind fields that are representative of surface layer marine atmospheric turbulence under different atmospheric stratifications. The spar floater’s motion responses from the simulations are then compared with the observations from Hywind Scotland’s 6 MW spar wind turbine. The platform’s pitch and yaw motions from the simulations are consistent with the observations, in terms of mean wind speed and atmospheric stratification. The simulations and the observations show that a stable atmosphere induces the lowest platform pitch and yaw motions compared to neutral and unstable stratifications. Nonetheless, the discrepancy of platform motions between stable and unstable conditions is more pronounced from the observations than in the simulations. Uncertainties associated with the estimation of the atmospheric stability and the modelling of the turbulence’s co-coherence for lateral separation may partly account for the discrepancies between the observed and the simulated motion responses of the spar wind turbine.
Towards gradient-based design optimization of fully-flexible tension-leg platform wind turbines
Authors: Rohrer P , Bachynski-Polić E E , Collette M
Published: November 2022

Novel technologies and design methods are needed to enable cost-competitive development of wind turbines with floating foundations. Tension-leg platforms have an established history in the oil and gas industry, though the complexity in coupled analysis of floating wind turbines generally has limited the exploration of novel concepts. The application of efficient, gradient-based optimization models has shown promise to overcome these difficulties and develop innovative designs. The core of this design optimization approach is an efficient coupled aero-hydro-servo-elastic dynamic model for a generic tension-leg platform wind turbine design, referred to as TLPOpt. The equation of motion is defined based on the generalized elastic mode shapes of the combined main column and tower. TLPOpt is implemented in the OpenMDAO framework for optimization, and analytical derivatives are defined throughout to increase efficiency. Stochastic dynamic analysis in the frequency-domain allows for efficient assessment of fatigue and extreme conditions. Verification steps show good agreement between the linearized analysis and higher-fidelity analysis tools. Early optimization studies suggest the optimization is able to improve upon a reference design, though more realistic constraint and objective functions are needed to draw further conclusions.
Hybrid deep-learning POD-based parametric reduced order model for flow around wind-turbine blade
Authors: Tabib Mandar V , Tsiolakis Vasileios , Pawar Suraj , Ahmed Shady E. , Rasheed Adil , Kvamsdal Trond , San Omer
Published: November 2022

In this study, we present a parametric, non-intrusive reduced order modeling (NIROM) framework as a potential digital-twin enabler for fluid flow around an aerofoil. A wind turbine blade has its basic foundation in the aerofoil shape. A faster way of understanding dynamic flow changes around the aerofoil-shaped blade can help make quick decisions related to wind-turbine operations and lead to optimal aerodynamic performance and power production. In this direction, a case study involving the application of the NIROM methodology for flow prediction around a NACA 0015 aerofoil is considered. The Reynolds number (Re) is the varying parameter, ranging from 320 000 to 1.12 million and high-fidelity CFD simulations are performed to generate the database for developing the NIROM. The aforementioned NIROM framework employs a Grassmann manifold interpolation approach (GI) for obtaining basis functions corresponding to new values of the parameter (Reynolds number), and exploits the time series prediction capabilities of the long short-term memory (LSTM) recurrent neural network for obtaining temporal coefficients associated with the new basis functions. The methodology involves: (a) an offline training phase, where the LSTM model is trained on the modal coefficients extracted from the sampled high-resolution data using the proper orthogonal decomposition (POD), and (b) an online testing phase, where for the new parameter value, the corresponding flow field is obtained using the GI-modulated basis functions for new parameter and the LSTM-predicted temporal coefficients. The NIROM-approximated flow predictions at new parameters have been compared to the high-dimensional full-order model (FOM) solutions for the high-Re aerofoil case and for a low-Re number wake vortex merger case in order to put the performance of NIROM in perspective. The results indicate that the NIROM framework can qualitatively predict the complex flow scenario around the aerofoil for new values of Reynolds number, while it has quantitatively shown that the LSTM predictions improve with the enrichment of the training space. For the low-Re vortex merger case, NIROM works very well. Thus, it can be deduced that there is scope and potential for continued research in NIROMs as digital twin enablers in wind energy applications.
Analysis of wind speed deviations between floating lidars, fixed lidar and cup anemometry based on experimental data
Authors: Wolken-Möhlmann Gerrit , Bischoff Oliver , Gottschall Julia
Published: November 2022

Floating lidar system (FLS) measurements are essential for offshore site assessment. Here an important part is the data accuracy and uncertainty, which are determined by the wind speed deviations between the FLS and reference data obtained during a verification trial. The reference anemometer is normally a cup anemometer installed on a met mast. Due to the different measurement principles, mast wake effects, the distance between FLS and reference, and FLS motions, the share of these factors in the deviations are not clear.

In this work, we present an FLS verification measurement conducted in proximity to the FINO3 met mast located in the North Sea in 2017. Additionally, the data acquired by a fixed, non-moving lidar installed on FINO3 is considered. This allows studying wind speed deviations with different, well-defined influence factors.

Methods for analyzing the wind speed accuracy and uncertainty, which are used in FLS verification and classification, are presented and applied to all combinations of data sources. As a preliminary work, directional wind speed deviations are studied to define a valid wind direction sector used for filtering for all data sources.

As a result, the wind speed deviations between the FLS and the references are dominated by the FLS motion and the distance to the reference, respectively. Nevertheless, uncertainties may also be seen for the fixed lidar. For the classification results, approximately 1/3 of the sensitivity is contributed by the different measurement principles.
Integrality in the Matching-Jack conjecture and the Farahat-Higman algebra
Authors: Ben Dali Houcine
Published: November 2022

Using Jack polynomials, Goulden and Jackson have introduced a one parameter deformationτb\tau _bof the generating series of bipartite maps, which generalizes the partition function ofβ\beta-ensembles of random matrices. The Matching-Jack conjecture suggests that the coefficientscμ,νλc^\lambda _{\mu ,\nu }of the functionτb\tau _bin the power-sum basis are non-negative integer polynomials in the deformation parameterbb. Dołęga and Féray have proved in 2016 the “polynomiality” part in the Matching-Jack conjecture, namely that coefficientscμ,νλc^\lambda _{\mu ,\nu }are inQ[b]\mathbb {Q}[b]. In this paper, we prove the “integrality” part, i.e. that the coefficientscμ,νλc^\lambda _{\mu ,\nu }are inZ[b]\mathbb {Z}[b].

The proof is based on a recent work of the author that deduces the Matching-Jack conjecture for marginal sumsc¯μ,lλ\overline { c}^\lambda _{\mu ,l}from an analog result for thebb-conjecture, established in 2020 by Chapuy and Dołęga. A key step in the proof involves a new connection with the graded Farahat-Higman algebra.
Gaussian phenomena for small quadratic residues and non-residues
Authors: Basak Debmalya , Nath Kunjakanan , Zaharescu Alexandru
Published: November 2022

Assuming the Generalized Riemann Hypothesis, it is known that the smallest quadratic non-residue modulo a prime

p
p

is less than or equal to

(
log
⁡
p

)
2

(\log p)^2

. Our aim in this paper is to establish the distribution of quadratic non-residues in even smaller intervals of size

(
log
⁡
p

)
A

(\log p)^A

with

A
>
1

A >1

, for almost all primes

p
p

.
Method validation of an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) assay for the analysis of Magnesium, Copper and Zinc in RBC
Authors: Bithi Nazmin , Ricks Daniel , Zuromski Lauren M , Kish-Trier Erik , Johnson-Davis Kamisha L
Published: November 2022

Background

Laboratory measurements of trace elements such as magnesium (Mg), copper (Cu) and zinc (Zn) in red blood cells (RBCs) are used to assess nutritional status and diagnose metal toxicity. The purpose of this study was to develop/validate an ICP-MS method for the quantification of these elements in RBCs.

Methods

An aliquot of packed RBCs was diluted in alkaline diluent solution containing scandium (45Sc) and gallium (71Ga), as internal standards, 0.1% Triton X-100, 0.1% EDTA, and 1% ammonium hydroxide (NH4OH). The diluted specimen was aspirated onto an ICP-MS for quantitative analysis of  25Mg,  63Cu and  66Zn. The method was validated for accuracy, precision, method comparison, linearity, analytical sensitivity, and carryover. Retrospective data was analyzed and non-parametric reference intervals (RIs) were calculated.

Results

Accuracy and linearity were within the expected range of =±15% for all analytes. Within-run, between-run, and total imprecisions were =15% CV. All other validation experiments met acceptance criteria. Established RIs for Mg, Cu and Zn in RBCs are 3.6-7.5 mg/dL, 59.0-91.0 mcg/dL and 794.0-1470.0 mcg/dL, respectively. Retrospective analysis of patient data for Mg RBC displayed no statistically significant difference in mean concentrations between adults (>18+ yr) and children (0-18 yr) (p >0.05); however, there was a significant difference in Mg concentrations between males and females (p < 0.001). The mean and SD for Mg RBC concentration for females and males were 5.38 + 0.68 mg/dL (n=8451) and 5.42 + 0.68 mg/dL (n=3954) respectively. The 95% RI was 4.2-6.9 mg/dL; >99% of patient results were within the established RI. Cu RBC mean concentrations were not statistically significant between males and females (p> 0.05) and age differences were not evaluated due to the low number of pediatric patients (n=37). The mean and SD for Cu concentrations were 72.2 + 11.7 mcg/dL (n=423). The overall 95% RI was 54.3-96.3 mcg/dL; 88.9% of patient results were within the established RI. For Zn RBC, there was a statistically significant difference in mean concentrations between children and adults (p < 0.0001) and no statistically significant difference between sex (p > 0.05). The mean and SD for Zn concentrations in children were 1103.7 + 225.5 mcg/dL (n=188). The 95% RI for this subgroup was 707.3– 1547.6 mcg/dL; 87.8% of pediatric patients were within the established RI. In adults, the mean and SD for Zn concentrations were 1311.7 + 196.2 mcg/dL (n=1579). The 95% RI was 932.5 – 1718.3 mcg/dL; 83.3% of patient results were within the established RI.

Conclusions

This method was validated and met criteria for clinical use to quantify three elements using ICP-MS for biological monitoring. Retrospective data analysis of patient results demonstrated that the method was suitable to assess nutritional deficiency and toxicity.
Compliance or Abuse? Detectable hydromorphone in patients taking oxycodone
Authors: Villalba Cristina Figueroa , Choucair Ibrahim , El-Khoury Joe
Published: November 2022

A middle-aged woman with recent cervical diskectomy with spinal fusion at C3-C4 suffered a mechanical fall with bilateral upper extremity paresthesia requiring admission but no surgical intervention. Patient was seen by orthopedic service and was recommended to continue using Aspen collar and oxycodone for pain. Following discharge, a drug urine screen test was performed, and showed positive for oxycodone by immunoassay. Confirmatory urine test by liquid chromatography-tandem mass spectrometry (LC-MS/MS) showed detectable oxycodone, oxymorphone and hydromorphone.

In patients treated with opioid therapy for chronic pain, urine drug monitoring is an important tool to ensure that patients are adhering to the prescribed medication. Hydrocodone and hydromorphone are not metabolites of oxycodone. However, hydrocodone can be present in oxycodone preparations with an estimated impurity of <1%. Hydrocodone can be metabolized into hydromorphone, although, there is no literature reporting detectable hydromorphone in patients’ urine with prescribed oxycodone only.

This case resulted in a quality improvement project where we evaluated the detection of hydrocodone and hydromorphone in positive oxycodone urine samples using LC-MS/MS. We analyzed 322 oxycodone positive urine samples. Twenty-one samples (6%) had detectable hydrocodone and/or hydromorphone below 100 ng/mL. Twelve out of the 21 were from patients taking no opioid medication other than oxycodone in the last week, with 33.3% showing detectable hydromorphone and 75% for hydrocodone below 100 ng/dL. The calculated hydrocodone/oxycodone (HC/OC) and hydromorphone/oxycodone (HM/OC) ratios were on average 0.26% HC/OC = 0.26% (0.05-0.69% SD 0.002; HM/OC = 0.26% (0.18-0.37% SD 0.001)] each (<1%). Patients taking oxycodone and other opioids had ratios >1% [HC/OC = 168% (3-563% SD 2.53; HM/OC = 699% (1.09-6585% SD 15.96)] and had higher detected levels (>100 ng/mL).

Pain management can be very challenging; therefore, laboratory testing provides an objective assessment of drug exposure and adherence to treatment. Cut-off values for considering positive the detection of hydrocodone and hydromorphone may change the interpretation of the drug urine tests in patients with prescribed oxycodone. Using higher cutoff (100 ng/mL) and the ratios HC/OC and HM/OC (<1%) may be useful to determine that the detection of these components is due to impurity of oxycodone formulation.