Miracle-dz/UniFAR-FTUs huggingface dataset:
Microstructural evolutions induced by an electrical breakdown in a binary Cu-25Cr alloy

Cu-Cr based alloys with a high Cr content are widely used as electrical contact materials in vacuum interrupters due to their good combination of electrical, thermal, and mechanical properties. During a current interruption process in a vacuum, the establishment of an electrical arc results in a severe local thermal input onto the contact material surface. Few studies have closely investigated the microstructural evolution during this phenomenon as well as the Cu-Cr alloy properties evolution. This study reports the microstructural, electrical conductivity, and hardness evolution of a Cu-25Cr (25 wt%Cr) solid state sintered alloy as electrical contact before and after successive current interruptions. Electron scanning and optical microscopy show that this microstructural evolution is a result of a complex phenomenon. Local and heterogeneous thermal conditions take place resulting in significant microstructural evolution. The resulting microstructure is related to out-of-equilibrium solidification conditions. Electrical conductivity is decreased by half in the whole thermally affected zone by the electrical arc and hardness is multiplied by three to four times.
Automated Driving for Global Nonpotential Simulations of the Solar Corona

We describe a new automated technique for active region emergence in coronal magnetic field models, based on the inversion of the electric field locally from a single line-of-sight magnetogram for each region. The technique preserves the arbitrary shapes of magnetic field distribution associated with individual active regions and incorporates emerging magnetic helicity (twist) in a parametrized manner through a noninductive electric field component. We test the technique with global magnetofrictional simulations of the coronal magnetic field during Solar Cycle 24 Maximum from 2011 June 1 to 2011 December 31. The active regions are determined in a fully automated and objective way using Spaceweather HMI Active Region Patch (SHARP) data. Our primary aim is to constrain two free parameters in the emergence algorithm: the duration of emergence and the twist parameter for each individual active region. While the duration has a limited effect on the resulting coronal magnetic field, changing the sign and amplitude of the twist parameters profoundly influences the amount of nonpotentiality generated in the global coronal magnetic field. We explore the possibility of constraining both the magnitude and sign of the twist parameter using estimates of the current helicity derived from vector magnetograms and supplied in the SHARP metadata for each region. Using the observed sign of twist for each region reduces the overall nonpotentiality in the corona, highlighting the importance of scatter in the emerging active region helicities.
An improved grey wolf optimization based MPPT algorithm for photovoltaic systems under diverse partial shading conditions

The photovoltaic (PV) systems are performing a substantial role in electric power systems for generating electrical power in various uncertain circumstances. Nonetheless, the PV systems face numerous challenges for power production in the event of partial conditions. Moreover, different types of multiple peak power points (MPPP) are generated in the characteristics of the PV system under diverse partial patterns. The MPPP’s having only one global maximum peak power (GMPP) and the remaining are local peak PowerPoints (LPPP), in which LPPP are interrupted to grab maximum power. Hence, improved grey wolf optimization (I-GWO) approach is developed in this work for enriching the required power generation at partial conditions. The proposed system has been designed in the MATLAB/Simulink environment. As per the simulation findings, the suggested I-GWO demonstrates great performance with regards to tracking time, accuracy, and efficiency as compared with other studied algorithms.
Ωbar in NGC 5597 from Very Large Array H i 21 cm Observations

We report Very Large Array B-configuration observations of the atomic hydrogen 21 cm line emission from the barred disk galaxy NGC 5597 at an angular resolution of ∼ 7. ″1 × 4. ″2. Using the resonance method, and assuming the ratio of the corotation radius to the semimajor axis of the stellar bar is unity ( ≡RCR/abar=1 ), we estimate the angular pattern speed of the stellar bar to be, Ωbar ∼ 15.3 km s−1 kpc−1. This constant value for Ωbar crosses Ωgas + κ(R)/4 at a distance ∼6.73 kpc, which would correspond to the spatial location of the north spiral structure near an outer m = 4 resonance. This value of Ωbar is similar to the values estimated for other bright nearby barred galaxies that exhibit circumnuclear rings (near inner Lindblad resonance) or outer rings (near outer Lindblad resonance).
Effect of thin tunnel layers MnO3 and V2O5 on the enhancement of single-layer organic solar cell efficiency

Layer thickness optimization has proven to be effective in the case of increasing Performance Conversion Efficiencies (PCE) of organic solar cells. In this research, optimization of the solar cell is performed and found an efficiency of 9.74%. After that, a solar cell with the insertion of some oxide layers is proposed. Two of them are the thick insulating oxide layers which have helped the efficiency to reach up to 15.23%. Under 1sun and at 1.5AM, the energy spectrum received from the sun has been calculated as 2.43eV for a 510nm light wavelength (has been considered as the peak among the visible light wavelengths), which is much more than the energy band gap of the active material. This incident is supposed to be one of the causes of the high electron tunnelling between the donor and acceptor of the LUMO (Lowest Unoccupied Molecular Orbital). Apart from its inorganic counterpart, as low charge carrier is the main concern for the organic solar cell, this can help a little by ensuring a high charge carrier and pushing the organic solar cell a step further with respect to its competitor, the inorganic solar cell.
Magnetoresistive behaviour of ternary Cu-based materials processed by high-pressure torsion

Severe plastic deformation using high-pressure torsion of ternary Cu-based materials (CuFeCo and CuFeNi) was used to fabricate bulk samples with a nanocrystalline microstructure. The goal was to produce materials featuring the granular giant magnetoresistance effect, requiring interfaces between ferro- and nonmagnetic materials. This magnetic effect was found for both ternary systems; adequate subsequent annealing had a positive influence. The as-deformed states, as well as microstructural changes upon thermal treatments, were studied using scanning electron microscopy and X-ray diffraction measurements. Deducing from electron microscopy, a single-phase structure was observed for all as-deformed samples, indicating the formation of a supersaturated solid solution. However, judging from the presence of the granular giant-magnetoresistive effect, small ferromagnetic particles have to be present. The highest drop in room temperature resistivity (2.45% at 1790 kA/m) was found in Cu62Fe19Ni19 after annealing for 1 h at 400 °C. Combining the results of classical microstructural studies and magnetic measurements, insights into the evolution of ferromagnetic particles are accessible.
Color-based shadow detection method in aerial images

This study evaluates the performance of shadow detection using different image color models. The pixel-level supervised classification procedure employed in this study includes filtering images, creating a trained shadow model, obtaining shadow masks and post-processing of the output masks. Considering the advent of drones usage, we discuss the results of shadow detection on aerial images. Based on the results, the method using YCbCr color features yielded 92.71% average accuracy. The low performance of shadow detection on images with small shadowed regions and images under various weather conditions indicated that additional investigation is necessary to create detection schemes for challenging input images with high spatial resolution.
High performance copper-tungsten @graphene composites materials

The contacts and fingers in the traditional high-voltage circuit breakers are all made of copper-tungsten alloy materials by powder metallurgy process at present. The conductivity and hardness of existing materials have reached the bottleneck, which can’t meet the requirements of working conditions. Graphene has good electrical conductivity, mechanical properties and high specific surface area. Doped into the traditional copper-tungsten alloy, graphene is expected to greatly improve the electrical conductivity and hardness of copper-tungsten electric contacts, which could make the alloy have excellent mechanical and electrical properties at the same time. It has become the main development direction of current electrical contact materials research. In this paper, the research progress of strengthening methods of traditional copper-tungsten electric contact materials by graphene and other reinforcing agents is systematically reviewed, and the strengthening mechanism of graphene on copper-tungsten electric contact materials is explored, which can provide technical guidance for the development and application of new high strength and high conductivity graphene-reinforced copper-tungsten electric contact materials with new performance and long electrical life.
High dimensional Hawkes processes

We generalise the construction of multivariate Hawkes processes to a possibly infinite network of counting processes on a directed graph $\mathbb G$. The process is constructed as the solution to a system of Poisson driven stochastic differential equations, for which we prove pathwise existence and uniqueness under some reasonable conditions. We next investigate how to approximate a standard $N$-dimensional Hawkes process by a simple inhomogeneous Poisson process in the mean-field framework where each pair of individuals interact in the same way, in the limit $N \rightarrow \infty$. In the so-called linear case for the interaction, we further investigate the large time behaviour of the process. We study in particular the stability of the central limit theorem when exchanging the limits $N, T\rightarrow \infty$ and exhibit different possible behaviours. We finally consider the case $\mathbb G = \mathbb Z^d$ with nearest neighbour interactions. In the linear case, we prove some (large time) laws of large numbers and exhibit different behaviours, reminiscent of the infinite setting. Finally we study the propagation of a {\it single impulsion} started at a given point of $\zz^d$ at time $0$. We compute the probability of extinction of such an impulsion and, in some particular cases, we can accurately describe how it propagates to the whole space.
LUDWIG MAXIMILIANS-UNIVERSITÄT MÜNCHEN

Lake Saint-Charles, situated north-west of Québec City in eastern Canada, is the largest drinking water reservoir for the city and supplies water to 300 000 residents. In recent years its trophic state has deteriorated and a premature aging has begun, placing the lake in an advanced mesotrophic state. Whilst the surface waters of Lake Saint-Charles have been closely monitored in the past, groundwater and atmospheric deposition have not been studied despite their great importance in understanding the state of the lake. Explorative modeling alongside with a field work campaign were conducted to quantify total suspended particles (TSP) concentrations and potential deposition on the lake coming from a nearby sand and gravel pit. TSP emissions from the sandpit were calculated with the air dispersion model AERMOD. Necessary information to define sources and calculate their emission rates were mainly estimated. The field work campaign included three high volume samplers placed in a linear progression in a SW wind direction channel, ideally showing the increase of TSP after the sandpit compared to the control and the concentration that is potentially found over the lake. Field work results showed no significant differences between the control station and the lake station, suggesting that no suspended particles from the sandpit reach the lake. No significant difference between sampling days with favorable and non-favorable wind conditions and wet and dry sampling days existed either. The very short sampling period and the small result count may be responsible for this result. The modeling showed an influx of TSP concentration and deposition onto the lake. The total estimated deposit of TSP on the lake was 1.16 t for the sampling period. Whether they originated from the sandpit or other activities in the surrounding area needs to be validated in further studies. It has to be noted that in the study area major road works and construction were under way. Local meteorological data and extensive knowledge concerning the sandpit's activity need to be made available to calculate more accurate results. Potential limnological impacts for Lake Saint-Charles can only be assumed at this point. It has to be noted that the TSP concentrations stayed under existing air quality standards. However, these standards do not take potential impacts on lakes into account. This project has contributed to establish the necessary improved method for long-term monitoring of the impact of atmospheric depositions. Based on this explorative study, the City of Québec and the Association pour la protection de l'environnement du Lac Saint-Charles et les Marais du Nord (APEL) (responsible for the monitoring activities in the area) will be able to install the necessary equipment, collect the missing information on the sandpits’ activities and to improve the monitoring methodology tested in this study.
Spitzer 3.6 and 4.5 μm full-orbit light curves of WASP-18

We present new light curves of the massive hot Jupiter system WASP-18 obtained with the Spitzer spacecraft covering the entire orbit at 3.6 and 4.5 μm. These light curves are used to measure the amplitude, shape and phase of the thermal phase effect for WASP-18 b. We find that our results for the thermal phase effect are limited to an accuracy of about 0.01 per cent by systematic noise sources of unknown origin. At this level of accuracy we find that the thermal phase effect has a peak-to-peak amplitude approximately equal to the secondary eclipse depth, has a sinusoidal shape and that the maximum brightness occurs at the same phase as mid-occultation to within about 5 ◦ at 3.6 μm and to within about 10 ◦ at 4.5 μm. The shape and amplitude of the thermal phase curve imply very low levels of heat redistribution within the atmosphere of the planet. We also perform a separate analysis to determine the system geometry by fitting a light curve model to the data covering the occultation and the transit. The secondary eclipse depths we measure at 3.6 and 4.5 μm are in good agreement with previous measurements and imply a very low albedo for WASP-18 b. The parameters of the system (masses, radii, etc.) derived from our analysis are also in good agreement with those from previous studies, but with improved precision. We use new high-resolution imaging and published limits on the rate of change of the mean radial velocity to check for the presence of any faint companion stars that may affect our results. We find that there is unlikely to be any significant contribution to the flux at Spitzer wavelengths from a stellar companion to WASP-18. We find that there is no evidence for variations in the times of eclipse from a linear ephemeris greater than about 100 s over 3 years.
Hyperkaehler Embeddings II

In the first part, Hyperkaehler Embeddings and Holomorphic symplectic Geometry I, we prove the following. Let $N$ be a closed analytic subvariety of a generic deformation of a holomorphically symplectic compact manifold $M$. Then the restriction of a holomorphic symplectic form is non-degenerate on $N$. In particular, $N$ is even-dimensional. In present paper, we prove that there exist a hyperkaehler metric on $M$, such that the embedding of $N$ to $M$ is hyperkaehler.
Retinal drusen: harbingers of age, safe havens for trouble

1 Department of Geriatric Medicine, Whitla Medical Building, Queen's University of Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK2 Centre for Vision Science, Royal Hospitals Trust, Grosvenor Road, Belfast, BT12 6BA, UKAddress correspondence to: Michael Williams. Tel: (+44) 2890972153; Fax: (+44) 2890325839. Email: mikewilliams99@hotmail.com Drusen are small focal extracellular deposits underneath the retina, visible ophthalmoscopically as yellow dots. The more hard drusen there are, the greater the risk of developing soft drusen and retinal pigmentary changes, which in turn increase the risk of developing advanced age-related macular degeneration. Much remains to be discovered about drusen. For the patient with drusen, basic advice on diet and smoking and maintenance of a high level of vigilance for visual changes is appropriate management. Keywords: retinal drusen, macular degeneration, vision: ocular, elderly
Deformation of the triangular spin-$\frac{1}{2}$ lattice in Na$_2$SrCo(PO$_4$)$_2$

Crystal structure and thermodynamic properties of Na$_2$SrCo(PO$_4$)$_2$, the chemical sibling of the triangular quantum spin-liquid candidate Na$_2$BaCo(PO$_4$)$_2$, are reported. From single crystal x-ray diffraction and high-resolution synchrotron x-ray powder diffraction, the compound was found to crystallize in the monoclinic space group $P2_1/a$ at room temperature, in contrast to the trigonal Na$_2$BaCo(PO$_4$)$_2$. Above 650 K, the symmetry of Na$_2$SrCo(PO$_4$)$_2$ changes to $C2/m$, while around 1025 K a further transformation toward trigonal symmetry is observed. The monoclinic symmetry leads to a small deformation of the CoO$_6$ octahedra beyond the trigonal distortion ubiquitous in this structure type, and results in the stronger $g$-tensor anisotropy ($g_{\text{z}}/g_{\text{xy}} = 1.6 $) as well as the increased XXZ anisotropy ($J_{\text{z}}/J_{\text{xy}} = 2.1$) compared to the Ba compound ($g_{\text{z}}/g_{\text{xy}} = 1.1 $, $J_{\text{z}}/J_{\text{xy}} = 1.5$), while the average coupling strength, $J_{\text{av}}/k_{\text{B}}=(2J_{\text{xy}}+J_{\text{z}})/3k_\text{B}\simeq 1.3\,\text{K}$, remains unchanged. The N\'{e}el temperature increases from 140 mK (Ba) to 600 mK (Sr), and an uncompensated in-plane moment of $0.066(4)\mu_{\text{B}}/\text{f.u. }$ appears. We show that the ordering temperature of a triangular antiferromagnet is capably controlled by its structural distortions.
Data Augmentation for Improving Emotion Recognition in Software Engineering Communication

Emotions (e.g., Joy, Anger) are prevalent in daily software engineering (SE) activities, and are known to be significant indicators of work productivity (e.g., bug fixing efficiency). Recent studies have shown that directly applying general purpose emotion classification tools to SE corpora is not effective. Even within the SE domain, tool performance degrades significantly when trained on one communication channel and evaluated on another (e.g, StackOverflow vs. GitHub comments). Retraining a tool with channel-specific data takes significant effort since manually annotating a large dataset of ground truth data is expensive. In this paper, we address this data scarcity problem by automatically creating new training data using a data augmentation technique. Based on an analysis of the types of errors made by popular SE-specific emotion recognition tools, we specifically target our data augmentation strategy in order to improve the performance of emotion recognition. Our results show an average improvement of 9.3% in micro F1-Score for three existing emotion classification tools (ESEM-E, EMTk, SEntiMoji) when trained with our best augmentation strategy.
Post-inflationary dark matter bremsstrahlung

Dark matter may only interact with the visible sector efficiently at energy scales above the inflaton mass, such as the Planck scale or the grand unification scale. In such a scenario, the dark matter is mainly produced out of equilibrium during the period of reheating, often referred to as UV freeze-in. We evaluate the abundance of the dark matter generated from bremsstrahlung off the inflaton decay products assuming no direct coupling between the inflaton and the dark matter. This process generally dominates the production of dark matter for low reheating temperatures where the production through the annihilations of particle in the thermal plasma becomes inefficient. We find that the bremsstrahlung process dominates for reheating temperatures T RH ≲ 1010 GeV, and produces the requisite density of dark matter for a UV scale ≃ 1016 GeV. As examples, we calculate numerically the yield of the dark matter bremsstrahlung through gravitation and dimension-6 vector portal effective interactions.
Seeing your sleep stage: cross-modal distillation from EEG to infrared video

It is inevitably crucial to classify sleep stage for the diagnosis of various diseases. However, existing automated diagnosis methods mostly adopt the"gold-standard"lectroencephalogram (EEG) or other uni-modal sensing signal of the PolySomnoGraphy (PSG) machine in hospital, that are expensive, importable and therefore unsuitable for point-of-care monitoring at home. To enable the sleep stage monitoring at home, in this paper, we analyze the relationship between infrared videos and the EEG signal and propose a new task: to classify the sleep stage using infrared videos by distilling useful knowledge from EEG signals to the visual ones. To establish a solid cross-modal benchmark for this application, we develop a new dataset termed as Seeing your Sleep Stage via Infrared Video and EEG ($S^3VE$). $S^3VE$ is a large-scale dataset including synchronized infrared video and EEG signal for sleep stage classification, including 105 subjects and 154,573 video clips that is more than 1100 hours long. Our contributions are not limited to datasets but also about a novel cross-modal distillation baseline model namely the structure-aware contrastive distillation (SACD) to distill the EEG knowledge to infrared video features. The SACD achieved the state-of-the-art performances on both our $S^3VE$ and the existing cross-modal distillation benchmark. Both the benchmark and the baseline methods will be released to the community. We expect to raise more attentions and promote more developments in the sleep stage classification and more importantly the cross-modal distillation from clinical signal/media to the conventional media.