bluuebunny/crossref_metadata_2025_split huggingface dataset:
First-principles study of the crystal and magnetic structures of multiferroic Cu2OCl2
Authors: Yen Peter Tsung-Wen , Wu Hung-Cheng , Huang Shin-Ming 
Published: June 2022

Abstract
Recently, the discovery of multiferroicity in pyrochlore-like compound Cu2OCl2 has generated significant interest, and several studies have been performed in this area. This transition metal oxychloride is unique because the divalent copper atoms create an

S
=
1

/

2

correlated insulator and the pyrochlore lattice tends to frustrate spins. From neutron powder diffraction measurements, an incommensurate magnetic order of the ordering vector

q

=
(
0.827
,
0
,
0
)

emerges below the Néel temperature of 70 K. At this temperature or slightly above, ferroelectricity (FE) or antiferroelectricity, accompanying a lattice distortion, has been observed. Experimentally, some discrepancies remain. In this paper, we report our first-principles simulation results by evaluating the possible lattice and spin spiral states. We found that the Fddd structure is not more stable than

F
d
d
2
(
a
)

, which is supported by our reexamination of the x-ray diffraction data. In addition, we find that after we include magnetism in the calculation, it predicts that the

F
d
d
2
(
a
)

lattice with a helical (proper screw) spin structure is energetically more stable than other spin configurations. Our results indicate charge-order-driven FE that subsequently induces magnetism.
Swelling as a stabilizing mechanism in irradiated thin films: II. Effect of swelling rate
Authors: Evans Tyler , Norris Scott 
Published: June 2022

Abstract
It has long been observed experimentally that energetic ion-beam irradiation of semiconductor surfaces may lead to spontaneous nanopattern formation. For most ion/target/energy combinations, the patterns appear when the angle of incidence exceeds a critical angle, and the models commonly employed to understand this phenomenon exhibit the same behavioral transition. However, under certain conditions, patterns do not appear for any angle of incidence, suggesting an important mismatch between experiment and theory. Previous work by our group (Swenson and Norris 2018 J. Phys.: Condens. Matter
30 304003) proposed a model incorporating radiation-induced swelling, which is known to occur experimentally, and found that in the analytically-tractable limit of small swelling rates, this effect is stabilizing at all angles of incidence, which may explain the observed suppression of ripples. However, at that time, it was not clear how the proposed model would scale with increased swelling rate. In the present work, we generalize that analysis to the case of arbitrary swelling rates. Using a numerical approach, we find that the stabilization effect persists for arbitrarily large swelling rates, and maintains a stability profile largely similar to that of the small swelling case. Our findings strongly support the inclusion of a swelling mechanism in models of pattern formation under ion beam irradiation, and suggest that the simpler small-swelling limit is an adequate approximation for the full mechanism. They also highlight the need for more—and more detailed—experimental measurements of material stresses during pattern formation.
Angular dependence of the upper critical induction of clean s- and d

x
2−y
2
-wave superconductors with self-consistent ellipsoidal effective mass and Zeeman anisotropies
Authors: Zhao Aiying , Gu Qiang , Klemm Richard A 
Published: June 2022

Abstract
We employ the Schrödinger-Dirac method generalized to an ellipsoidal effective mass anisotropy in order to treat the spin and orbital effective mass anisotropies self consistently, which is important when Pauli-limiting effects on the upper critical field characteristic of singlet superconductivity are present. By employing the Klemm–Clem transformations to map the equations of motion into isotropic form, we then calculate the upper critical magnetic induction

B

c
2

(
θ
,
ϕ
,
T
)

at arbitrary directions and temperatures T for isotropic s-wave and for anisotropic

d

x
2

−

y
2

-wave superconducting order parameters. As for anisotropic s-wave superconductors,

B

c
2

is largest in the direction of the lowest effective mass, and is proportional to the universal orientation factor

α
(
θ
,
ϕ
)

. However, for

d

x
2

−

y
2

-wave pairing and vanishing planar effective mass anisotropy,

B

c
2

(
π

/

2
,
ϕ
,
T
)

exhibits a four-fold azimuthal pattern with C
4 symmetry the maxima of which are along the crystal axes just below the transition temperature T

c
, but these maxima are rotated by

π

/

4

about the z axis as T is lowered to 0. However for

d

x
2

−

y
2

-wave pairing with weak planar effective mass anisotropy,

B

c
2

(
π

/

2
,
ϕ
,
T
)

exhibits a two-fold pattern with C
2 symmetry for all

T

⩽

T
c

, which also rotates by

π

/

4

about the z axis as T is lowered to 0. These low planar effective mass anisotropy cases provide a new method to distinguish s-wave and

d

x
2

−

y
2

-wave pairing symmetries in clean unconventional superconductors.
An investigation into potential improvements in the design of lead glasses for protecting the eyes of interventional cardiologists
Authors: Honorio da Silva Edilaine , Martin Colin J , Vanhavere Filip , Dabin Jérémie , Buls Nico 
Published: June 2022

Abstract
The lens of the eye can be damaged by ionising radiation, so individuals whose eyes are exposed to radiation during their work may need to protect their eyes from exposure. Lead glasses are widely available, but there are questions about their efficiency in providing eye protection. In this study, Monte Carlo simulations are used to assess the efficiency of lead glasses in protecting the sensitive volume of the eye lens. Two designs currently available for interventional cardiologists are a wraparound (WA) style and ones with flat frontal lenses with side shielding. These designs were considered together with four modifications that would impact upon their efficiency: changing the lead equivalent thickness, adding lead to the frames, elongating the frontal lenses, and adding a closing shield to the bottom rim. For the eye closest to the source, standard models of lead glasses only decrease the radiation reaching the most sensitive region of the eye lens by 22% or less. Varying the lead thickness between 0.4 mm and 0.75 mm had little influence on the protection provided in the simulation of clinical use, neither did adding lead to the frames. Improved shielding was obtained by elongating the frontal lens, which could reduce radiation reaching the eye lens by up to 76%. Glasses with lenses that had a rim at the base, extending towards the face of the user, also provided better shielding than current models, decreasing the dose by up to 80%. In conclusion, elongating the frontal lens of lead glasses, especially of the WA design, could provide a three-fold increase in shielding efficiency and this is still valid for lenses with 0.4 mm lead equivalence.
A dual-camera single-shot lifetime method with fully controllable exposure gates for pressure-sensitive paint measurements on fast-rotating surfaces
Authors: Li Yongzeng , Dong Zhe , Peng Di , Liu Yingzheng 
Published: June 2022

Abstract
This paper proposes a dual-camera single-shot lifetime method for pressure-sensitive paint (PSP) measurements on fast-rotating surfaces. Two cameras with fully controllable exposure gates are used for image acquisition to reduce the motion blur due to the open-ended exposure of the interline transfer charge-coupled device camera which was typically used for the single-shot lifetime method. The images can thus be processed without deblurring for a wider rotating speed range than is possible with existing techniques. More importantly, both frames have equal exposure times and therefore equal blur lengths. This enables precise pixel-to-pixel image matching and minimizes image registration errors. In addition, the signal strengths of the frames can be balanced, enabling shot-noise-induced errors to be reduced by independent adjustment of the aperture ratio. A pressure uncertainty estimation model is established to evaluate the measurement errors, which helps determine the system parameters. The dual-camera PSP system is calibrated and then validated through the surface pressure measurement of a fast-rotating disk. It is found that the exposure time t
e has little effect on the PSP sensitivity, whereas the delay time t
d affects both the pressure sensitivity and the measurement error. Both t
e and t
d are set to 5 μs in the rotating disk experiment. Images with a blur length of 1.4 pixels are captured and processed without deblurring to yield reasonable surface pressure results. The pressure error is decreased from 1.05 to 0.65 kPa by increasing the aperture ratio F from 2 to 4.
Face-lifting the surface of LiNi0.8Co0.15Al0.05O2 cathode via Y(PO3)3 to form an in situ triple composite Li-ion conductor coating layer with the enhanced electrochemical performance
Authors: Cheng Wendong , Li Lei , Hao Shuai , Liu Ling , Wu Yuxuan , Huo Jinsheng , Ji Yuyao , Liu Xingquan 
Published: June 2022

Abstract
Due to the assets such as adequate discharge capacity and rational cost, LiNi0.8Co0.15Al0.05O2 (NCA), a high-nickel ternary layered oxide, is regarded to be a favorable cathode contender for lithium-ion batteries. However, the superior commercial application is restricted by the surface residual alkaline lithium salt (LiOH or/and Li2CO3) of nickel-rich cathode materials, which will expedite the disintegration of the structure and the engendering of gas (CO2). Therefore, in this paper, we devise and fabricate a Y(PO3)3 modified LiNi0.8Co0.15Al0.05O2 (NCA), intending to optimize the surface residual alkaline lithium salt (antecedent deportation of H2O and CO2) while forming an in situ triple composite Li-ion conductor coating (Y(PO3)3-Li3PO4-YPO4) to enhance the electrochemical behavior. Under this method, the 2 mol% Y(PO3)3 modified NCA electrode reveals exceptional rate capability (5 C/156.3 mAh g−1) and extraordinary cycle stability after 200 cycles (2 C/88.3%), whereas the original sample is only 5 C/123.1 mAh g−1 and 2 C/71.2% after 200 cycles. Conspicuously, even under the draconian circumstances of the high temperature and the high rate at 55 °C/1 C, the 2 mol% Y(PO3)3 modified NCA electrode sustains a high reversible capacity, with an admirable capacity retention rate of 89.4% after 100 cycles. These contented results signify that the surface remodeling tactic presents a viable scheme for ameliorating high-nickel materials’ performance and appropriateness.
Polymer chalcogenides—new smart materials for thermoelectric applications
Authors: Maity Shilpa , Parvin Umme Karnij Salma , Das Sukhen , Chatterjee Krishanu 
Published: June 2022

Abstract
The breakthrough invention of conducting polymers (CPs) initiates a new pathway for the researchers to make use of their properties in thermoelectric (TE) applications. They are considered to be potential candidates in TE application when combined with inorganic counterparts. Different strategies were undertaken to enhance structural order and hence the TE performance of the CPs which trigger the scientific community to focus more on this area. Consequently, the use of nano filler in the polymer matrix proved to be a better way to improve the TE properties and chalcogenide materials could be the best candidates to be used as nano filler due to their high TE parameters. Thus, composites of CPs with different chalcogenides have been drawing attention in the field of TEs in recent years. The present work points towards a comprehensive update on different synthesis process of composites of various CPs with a number of chalcogenides along with a state-of-art review of these promising materials in TEs for device applications with the expectation that this work will surely motivate the researchers to optimize the best candidate.
Experimental study of surface roughness on improving the tribological performance of sealing pairs in magnetorheological damper
Authors: Li Shanshan , Xiu Shichao , Song Wanli , Sun Cong , Yang Heng 
Published: June 2022

Abstract
Comprehension of the tribological behavior of magnetorheological fluid (MRF) is crucial in many fields, particularly those related to seal wear. The sealing conditions are more complex than traditional media due to composition and rheological characteristics of MRF. The sealing pairs are prone to wear failure when in contact with magnetic particles. To this end, the paper focuses on the influence of surface roughness on MRF tribological properties with and without magnetic field. The whole experiment is carried out by a self-developed device to reproduce the wear evolution between the sealing pairs for magnetorheological damper. Experimental results show that higher surface roughness exhibits lower friction coefficient and better friction performance under MRF, especially in the absence of magnetic field. This is in stark contrast to the best wear resistance exhibited by polished samples under methyl silicone oil, a carrier fluid of MRF. This means that the effective coupling between surface roughness and iron particles helps to improve the friction and wear performance of sealing pairs. On this basis, the optimum surface roughness values of metal pin under MRF are obtained. Subsequently, the effect of pin surface morphology on the dynamics of iron particles are confirmed through the analysis of scanning electron microscopy images. It is further demonstrated that wear mechanism varies with surface roughness, that is, as the roughness increases, from sliding to mixing, and finally to rolling. Consequently, this research is of great significance for improving the wear resistance of sealing pairs under MRF.
Coexistence of hyperchaos with chaos and its control in a diode-bridge memristor based MLC circuit with experimental validation
Authors: Fonzin Fozin Theophile , Nzoko Bernard Koumetio , Telem Nicole Adelaide Kengnou , Njitacke Zeric Tabekoueng , Mouelas Adele Armele Ngo , Kengne Jacques 
Published: June 2022

Abstract
This paper reports both the coexistence of chaos and hyperchaos and their control based on a noninvasive temporal feedback method for attractor selection in a multistable non-autonomous memristive Murali-Lakshamanan-Chua (MLC) system. Numerical simulation methods such as bifurcation diagrams, the spectrum of Lyapunov exponents, phase portraits, and cross-section basins of initial states are used to examine several striking dynamical features of the system, including torus, chaos, hyperchaos, and multistability. Of most interest, the rare phenomenon of the coexistence of hyperchaos and chaos has been uncovered based on bifurcation techniques and nonbifurcation scheme like offset boosting. Further analyses based on intermittent feedback-based control in the time domain help to drive the system from the multistable state to a monostable one where only the hyperchaotic attractor survives. Since the attractor’s internal dynamics are retained, this control method is non-invasive. At the end of our analyses, the results of both PSpice and that of the microcontroller-based digital calculator of the circuit match perfectly with the numerical investigations.
Tuning intrinsic defects in ZnO films by controlling the vacuum annealing temperature: an experimental and theoretical approach
Authors: Paz-Corrales K J , Vilca-Huayhua C A , Aragón F F H , Villegas-Lelovsky L , Coaquira J A H , da Silva S W , Marques G E , Teodoro M D , Pacheco-Salazar D G 
Published: June 2022

Abstract
The control of native defects in the ZnO material is strongly important for a wide range of technological applications. In this paper, native defects are tuned via the post-thermal treatment of ZnO films in a high vacuum atmosphere. The microstructure of the as-grown ZnO film shows columnar growth and strongly polar-oriented grains along the c-plane (002). Also, the obtained results indicate that the as-grown film contains a high amount of intrinsic defects and strong lattice distortions. After the thermal annealing, the ZnO films display significant structural changes, which are reflected in their electrical, vibrational, and optical properties. Our findings suggest that these changes were attributed to the selective cleanup effect of the native defects and the partial deoxidation process mainly on the exposed particle surface (at high temperatures) tuned up by the thermal annealing temperature. According to DFT calculations, oxygen vacancies (V

O
) show lower energy, followed by zinc vacancies (V
Zn
) and oxygen interstitials (O
i
) indicating that V

O
defect is the most stable in ZnO. That sequence of stability could suggest the sequence of the annihilation of those defects, which is in line with our experimental findings and also in agreement with literature results.
Visual biospeckle analysis of just torn plant leaf using frequency filtering
Authors: Koley Chhanda , Nirala Anil Kumar 
Published: June 2022

Abstract
Biospeckle activity in leaves arise due to the contribution of several phenomena like water content, respiration, transpiration etc. Our present research work deals with the biospeckle activity of a plant leaf using the laser biospeckle technique and wavelet transform just after removal from the plant, to isolate physiological activities like respiration, transpiration etc over water activity for the first time to the best of our knowledge. Visual analyses of biospeckle activities of Mangifera indica and Tabernaemontana divaricata leaves have been done with the help of spectral activity maps obtained using fujii and parameterized geometrical mean of temporal difference algorithms. Mid-vein and other veins are mainly responsible for water transportation whereas different physiological activities occur in both veins and lamina parts of the leaf. As the biospeckle activity due to high water content suppresses the activity due to other physiological phenomena of the leaf, the spectral activity map without any frequency filtering shows the higher activity of the mid-vein than that of the lamina part of the leaf. It has already been established by researchers that the exclusion of lower frequency bands represents physiological activities of biological samples. Spectral activity maps considering the individual frequency bands starting from 13 and 12 onwards in the case of M. indica and T. divaricata leaves are able to represent the physiological phenomena of the leaves respectively. In comparison to the results obtained considering the individual frequency bands, the results obtained by removing the frequency band groups 1–12 (6.25–3.25 Hz frequency range) for M. indica leaf and 1–11 (6.25–3.50 Hz frequency range) for T. divaricata leaf clearly represent the physiological activities over the water activity of those leaves respectively. Also, biospeckle activities using the individual frequency bands along with the exclusion of band groups 13–25 (3.25–0.00 Hz frequency range) and 12–25 (3.50–0.00 Hz frequency range) represent the water activity of the above two leaves respectively.
Analysis of the effects of scanning trajectory parameters on minute-scale lidar forecasting
Authors: Ortensi M , Theuer F , Kühn M 
Published: June 2022

Abstract
The definition of the lidar scan parameters for a measurement campaign can be complex and unsure due to the distinct effects that they cause on the lidar output. In order to study those effects on minute-scale lidar forecasting, we simulated several lidar trajectories in a large eddy simulation wind field. We analysed the effects of changes in range gate spacing, and angular and temporal resolution on the accuracy of wind field reconstruction and on the forecast skill of 5 minute ahead deterministic wind speed forecasts. We found that the range gate spacing has no influence on forecast skill. Furthermore, we discussed the forecasting improvement caused by the increase in angular resolution, and its unexpected worsening caused by the reduction in temporal resolution. We concluded that high values for range gate spacing do not reduce the forecast skill, and that the effects of changes in angular and temporal resolution on forecast accuracy can differ among the wind turbines.
Modeling extreme weather events for offshore wind in the North Sea: a sensitivity analysis to physics parameterizations in WRF
Authors: Vemuri Adithya , Munters Wim , Buckingham Sophia , Helsen Jan , Beeck Jeroen van 
Published: June 2022

AbstractExtreme weather events such as storms, cold fronts, and mesoscale convective systems, are capable of producing extreme and sudden precipitation, strong wind gusts and fast changes in wind direction, which are potentially harmful for the operation, power production and maintenance of wind farms. This study aims to provide insight into the modelling of three such events for the offshore wind farms located in the Belgian North Sea. This work extends the ongoing work on generalizing WRF model sensitivities to multiple extreme weather events. This sensitivity analysis considers three cases consisting of Storm Ciara, a low-pressure system and a cold front. These events are modeled using five model setups comprising different combinations of WRF physics parameterizations. The simulated wind direction and speed are evaluated against 10-min averaged SCADA data. The results indicate no single best model setup to accurately simulate all events. The combination of physical parameterization is observed to play a major role in model sensitivities. The use of scale-aware physical parameterization show potential for better performance but is heavily influenced by the combination of model physics and the type of event. No conclusive set of inferences are obtained from a qualitative evaluation of precipitation against observed radar data.
A numerical investigation of a wind turbine wake in non-neutral atmospheric conditions
Authors: Baungaard M. , Abkar M. , van der Laan M.P. , Kelly M. 
Published: June 2022

Abstract
Wind turbine wakes cause energy losses and increased blade fatigue loads in wind farms. The magnitude of these effects depend strongly on the atmospheric conditions. In nonneutral atmospheric conditions, there is a turbulence kinetic energy (TKE) contribution from buoyancy, either positive (convective boundary layer, CBL) or negative (stable boundary layer, SBL). In this work, both conditions are analyzed with new large-eddy simulation (LES) data of a single wind turbine wake in flat, homogeneous terrain to quantify the effects of buoyancy. It is found that the buoyancy contribution is negligible compared to the shear production in the wake region and the role of buoyancy is therefore mainly to alter the inflow profiles. This fact is used in a simple Reynolds-averaged Navier-Stokes (RANS) turbulence model, which shows reasonable results for wake velocity deficit compared to LES data.
Influence of nacelle-lidar scanning patterns on inflow turbulence characterization
Authors: Fu Wei , Sebastiani Alessandro , Peña Alfredo , Mann Jakob 
Published: June 2022

Abstract
Nacelle lidars with different number of beams, scanning configurations and focus distances are simulated for characterizing the inflow turbulence. Lidar measurements are simulated within 100 turbulence wind fields described by the Mann model. The reference wind turbine has a rotor diameter of 52 m. We assume homogeneous frozen turbulence over the lidar scanning area. The lidar-derived Reynolds stresses are computed from a least-square procedure that uses radial velocity variances of each of the beams and compared with those from a simulated sonic anemometer at turbine hub height. Results show that at least six beams, including one beam with a different opening angle, are needed to estimate all Reynolds stresses. Enlarging the beam opening angle improves the accuracy and uncertainty in turbulence estimation more than increasing the number of beams. All simulated lidars can estimate the along-wind variance accurately. This work provides guidance on designing and utilizing nacelle lidars for inflow turbulence characterization.