bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-extremal near-horizon geometries
Authors: Fontanella Andrea 
Published: May 2023

Abstract
When Gaussian null coordinates are adapted to a Killing horizon, the near-horizon limit is defined by a coordinate rescaling and then by taking the regulator parameter ɛ to be small, as a way of zooming into the horizon hypersurface. In this coordinate setting, it is known that the metric of a non-extremal Killing horizon in the near-horizon limit is divergent, and it has been a common practice to impose extremality in order to set the divergent term to zero. Although the metric is divergent, we show for a class of Killing horizons that the vacuum Einstein’s equations can be separated into a divergent and a finite part, leading to a well-defined minimal set of Einstein’s equations one needs to solve. We extend the result to Einstein gravity minimally coupled to a massless scalar field. We also discuss the case of Einstein gravity coupled to a Maxwell field, in which case the separability holds if the Maxwell potential has non-vanishing components only in the directions of the horizon spatial cross section.
Semi-supervised echo state network with partial correlation pruning for time-series variables prediction in industrial processes
Authors: Huang Jian , Wang Fan , Yang Xu , Li Qing 
Published: May 2023

Abstract
For an ordinary echo state network (ESN), redundant information in the huge reservoir will lead to degradation of the prediction performance of the network, especially when the labels of the samples are limited. To solve this problem, a semi-supervised ESN with partial correlation pruning (PCP-S2ESN) is proposed in this paper to scientifically capture the essential association between two reservoir variables while controlling for the influence of other factors. In this way, redundant neurons and their connection weights in the reservoir are eliminated, so that the prediction accuracy is significantly enhanced by optimizing the network structure. Moreover, an unsupervised pre-training procedure is introduced to modify the input weight matrix and reservoir connection weight matrix of the ESN, which successfully achieves precise prediction of time-series variables with limited labels. The superiority of the PCP-S2ESN model is demonstrated through two benchmark prediction tasks and the fed-batch penicillin cultivation process.
Comparison of optical feedback cavity enhanced absorption spectroscopy and gas chromatography for the measurement of the main components and impurities in biogas, landfill gas, biomethane and carbon dioxide streams
Authors: Arrhenius Karine , Francini Lorena , Fischer Andreas , Büker Oliver , Arques Laurent Garcia 
Published: May 2023

Abstract
In this study, we evaluated the performances of a custom-built optical feedback cavity enhanced absorption spectroscopy (OFCEAS) instrument for the determination of the composition of energy gases, focusing on methane and carbon dioxide as main components, and carbon monoxide as impurities, in comparison with the well-established, validated, and traceable gas chromatographic method. A total of 115 real sample gases collected in biogas plants or landfills were analyzed using with both techniques over a period of 12 months. The comparison of the techniques showed that the virtual model which allows the measurement, needs to be optimized using real samples of varied compositions. The OFCEAS measurement technique was found to be capable of measuring both the main components and a trace component in different matrices; to within a 2% measurement uncertainty (higher than the gas chromatograph/thermal conductivity detector (GC/TCD) method). The OFCEAS method exhibits a very fast response, does not require daily calibration, and can be implemented online. The agreements between the OFCEAS technique and the GC/TCD method show that the drift of the OFCEAS instruments remains acceptable in the long term as long as no change is made to the virtual model. Matrix effects were observed, and those need to be taken into consideration when analyzing different types of samples.
A new noise reduction method based on re-weighted group sparse decomposition and its application in gear fault feature detection
Authors: Zheng Xianbin , Cheng Junsheng , Nie Yonghong , Yang Yu 
Published: May 2023

Abstract
Aiming at the problem that gear vibration signals are susceptible to noise and the difficulty of extracting fault features, this paper proposes a new noise reduction method based on re-weighted group sparse decomposition (RWGSD). RWGSD introduces group sparse mode decomposition theory to protect the structural information of signal components in the frequency domain. On this basis, vital components are screened according to the time-domain characteristics of fault information, and the re-weighted enhancement is carried out. The fault characteristics are easy to identify in the final noise reduction result. In addition, RWGSD defines two new indicators, cyclic re-weighted kurtosis (CRWK) and re-weighted cyclic intensity (RWCI). CRWK can assess the intensity of periodic characteristic components and has some resistance to strong impact interference. RWCI can evaluate the magnitude of fault information, overcoming the limitations of traditional noise reduction techniques that screen out vital components based on energy size. Numerical simulation and real-world experiment results show that the proposed method has excellent performance in noise removal, increases the reliability of gear fault feature detection, and has certain practical values.
Ultranarrow-band filterless photodetectors based on CH3NH3PbCl
x
Br3–x
mixed-halide perovskite single crystals
Authors: Lu Chengyu , Zhou Juanjuan , Tang Chenyu , Dai Qinyong , Peng Yingquan , Lv Wenli , Sun Lei , Xu Sunan , Hu Weida 
Published: May 2023

Abstract
Narrow-band photodetectors based on halide perovskite have recently attracted significant attention due to their exceptional narrow-band detection performance and tunable absorption peaks covering a wide optical range. In this work, we report mixed-halide CH3NH3PbCl
x
Br3–x
single crystal-based photodetectors have been fabricated, where the Cl/Br ratios were varied (3:0, 10:1, 5:1, 1:1, 1:7, 1:14 and 0:3). Vertical and parallel structures devices were fabricated which exhibited ultranarrow spectral responses under bottom illumination, with a full-width at half-maximum less than 16 nm. The observed performance can be ascribed to the unique carrier generation and extraction mechanisms within the single crystal under short and long wavelength of illumination. These findings offer valuable insights into the development of narrow-band photodetectors that do not necessitate the use of filters and hold tremendous potential for a diverse array of applications.
Gravitational wave signals from leptoquark-induced first-order electroweak phase transitions
Authors: Fu B. , King S.F. 
Published: May 2023

Abstract
We consider the extension of the Standard Model (SM) with scalar leptoquarks in SU(2)
singlet, doublet and triplet representations. Through the coupling between leptoquark and the SM
Higgs field, the electroweak phase transition (EWPT) can turn into first-order and consequently
produce gravitational wave signals. We compute the required value of the leptoquark-Higgs for
first-order EWPT to happen and discuss about the possible constraint from Higgs
phenomenology. Choosing some benchmarks, we present the strength of the gravitational waves
produced during the leptoquark-induced first-order EWPT and compare them to detector
sensitivities. We find that the SU(2) representations of the leptoquark can be distinguished by
gravitational waves in the parameter space where first-order EWPT can happen as a function of the
Higgs portal coupling.
Numerical study on latent heat thermal energy storage with phase change material and metal foam in shell and corrugated tube with external heat losses
Authors: Buonomo Bernardo , Golia Maria Rita , Manca Oronzio , Nardini Sergio , Plomitallo Renato Elpidio 
Published: May 2023

Abstract
In the present work, a numerical investigation of the Latent Heat Thermal Energy Storage system (LHTESs) is performed on a vertical shell and tube geometry, made of a porous medium filled with a phase change material (PCM). The LHTESs is a cylinder with a corrugated inner surface at a constant temperature above the PCM melting temperature; on the external surface there are heat losses to the outside and the top and bottom surfaces are adiabatic. The PCM used is a pure paraffin wax, the metal foam, instead, is made of aluminum. The phase change process is modelled with the enthalpy-porosity theory, while the Local Thermal Non-Equilibrium (LTNE) and the Darcy-Forchheimer models are adopted to analyse the heat transfer between the paraffin and the metal foam. The solutions of the governing equations are computed with Ansys-Fluent commercial code. The survey considers different conductivity variations on the external wall and distinct corrugated wall geometric parameters, with different wavelengths and wave amplitudes. The results of the numerical simulations, concerning the LHTESs charging phase, are reported as a function of time and compared in terms of melting time, enthalpy stored, and energy loss.
Analysis of Variance of the Heat and Mass Transfer Coefficients in an Evaporative Condenser
Authors: Giovannini Michael , Lorenzini Marco 
Published: May 2023

Abstract
Modelling of evaporative condensers relies heavily on the correct choice of the correlations for transport coefficients to give an accurate estimate of the dissipated thermal load and evaporated water mass flowrate, yet the literature does not cover all flow arrangements, nor operating conditions. In order to avoid expensive, and often impractical, experimental campaigns devoted to the determination of these quantities for a specific piece of equipment, a statistical approach based on the analysis of variance can be adopted: by analysing the sensitivity of the dependent variables on the choice of the transport coefficients, the best set of correlations can be determined, depending on whether a more accurate estimate is desired for the heat flux or evaporated mass flowrate, or if both are equally important.
Reverse flow in a pressure suppression system due to condensation instabilities
Authors: Giambartolomei G. , Pesetti A. , Berti L. , Raucci M. , Lazzeri R. , Aquaro D. 
Published: May 2023

Abstract
The Vacuum Vessel Pressure Suppression System (VVPSS) is designed to protect the ITER reactor (Vacuum Vessel, VV) from an overpressurization accident. The VVPSS is mainly composed of four Vapour Suppression Tanks (VSTs) partially filled with water inside which venting pipes (spargers) are immersed to direct the steam in the subcooled pool to condense it. Since the maximum pressure allowed inside the VV is only 0.15 MPa, a sub-atmospheric pressure must be maintained inside the VSTs. During a series of experimental campaigns funded by ITER Organization to study and validate the correct operability of the VVPSS and conducted in a large-scale plant built at the B. Guerrini laboratory of the University of Pisa, pressure instability and reverse flow through the sparger holes have been observed. The analysis of acceleration signals recorded during this pressure inversion, showed large amplitude oscillations at low frequency due to the Condensation Induced Water Hammer (CIWH).
Caesium balance of the ISIS H- Penning ion source in long pulse operation
Authors: Tarvainen Olli , Faircloth Dan , Lawrie Scott 
Published: May 2023

Abstract
We have developed a semi-empirical model predicting the equilibrium caesium coverage (in
monolayers) and the resulting work function of the ISIS Penning ion source cathode (in eV) in long
pulse operation. We use the caesium balance model to predict the temporal structure of the
extracted H- beam current pulses and compare the model predictions to experimental data with
60 mA, 2 ms beam pulses at 50 Hz. The experimentally
observed droop of the beam current is reproduced by the model. The results imply that extracting
square beam pulses in the long pulse operation mode requires more efficient cathode cooling. We
apply the model for 70 mA, 3 ms beam pulses at 14 Hz,
relevant for ESSνSB project. We conclude that achieving these parameters requires reducing the
cathode temperature by 200 °C, and ramping the discharge current to cancel the
discharge voltage droop.
Long-duration bipolar linear transformer driver based on a multi-turn half-bridge structure
Authors: Shang Tianyi , Shen Saikang , Sun Guoxiang , Ding Weidong 
Published: May 2023

Abstract
All-solid linear transformer driver(LTD) generators are widely used to output unipolar high-voltage rectangular pulses in nanoseconds. However in some applications, the bipolar output is necessary and the size of the generator is limited, which is challenging for LTD topology because the size of the magnetic core is related directly to the amplitude and pulse duration of the output waveforms. In this paper, a bipolar long-duration pulse generator based on the topology of a linear transformer driver combined with a half-bridge and multi-turn structure is put forward. The half-bridge topology can output bipolar waveforms easily and can save the number of switches used in the generator. To eliminate the crosstalk voltage that appears during operation, a differential mode inductance is used to protect the circuit. A snubber circuit is applied to suppress the reverse overshoot. The multi-turn design is chosen to make the size more compact. However, the multi-turn usually leads to a lower rise speed. To improve the performance, an optimization method that improves the rising speed by changing the turns of each stage is discussed. The strategy is useful and can be applied on some other occasions. The generator can output bipolar waveforms whose amplitudes are 4 kV and the duration can be adjusted from 200 ns to 800 ns. The rise time can be limited to 70 ns. The size of the generator is
10 cm * 10 cm * 15 cm, which is compact compared to the generators put forward before.
Dose estimation in X-ray backscatter imaging with Timepix3 and TLD detectors
Authors: Useche Parra J.S. , Schütz M.K. , Roque G. , Fey J. , Avila C. , Fiederle M. , Procz S. 
Published: May 2023

Abstract
Nowadays, the detection of backscatter X-rays has become an
essential part of road security scanners, where individuals are at
risk of an accidental exposure to the pulsed photon radiation fields
generated by the devices that implement this technique. Dose to
soft-tissue measurements of a pulsed radiation field generated by a
commercial cargo X-ray backscattering device are presented using a
Timepix3 detector. To accurately estimate the imparted dose, the
energy spectrum of a backscattering cargo scanner is measured with a
thick CdZnTe hybrid semiconductor pixel detector. The deconvolution
of this measured spectrum is performed and the contributions to the
dose are calculated by means of the mass energy-absorption
coefficients for soft-tissue. This methodology was assessed through
a Monte-Carlo simulation, together with verification measurements
using thermoluminescent detectors (TLDs) as a standard dosimetry
system. Measurements of direct irradiation, for a 30 s scan with
the device at 2 m from the detector, yielded a dose of
(4.9 ± 0.7) μGy and (3.6 ± 0.3) μGy for the
Timepix3 and TLDs, respectively. In a simulated cargo environment,
with the detector behind a 1 mm thick steel wall, 30 s scan time,
and 2 m source to detector distance, the dose measured by the
Timepix3 was (1.7 ± 0.1) μGy, while for the TLDs
(1.4 ± 0.6) μGy, showing that the proposed methodology has
a similar response as compared to a standard dosimetry system.
Monolithic scintillator PET detector by using light sharing between adjacent detector modules
Authors: Sun M.D. , Zhang C.H. , He Z. , Wang H.J. 
Published: May 2023

Abstract
A monolithic crystal-based positron emission tomography
(PET) detector has a low cost and high sensitivity and allows
determining 3D positions by scintillation light
distribution. However, the edge effect inherent to scintillators
deteriorates the position resolution of the detector toward the
crystal borders due to the escape and reflection of the
scintillation light. An increase in crystal thickness will improve
the detection efficiency, but the edge effect becomes severe. To
improve the position resolution and detection efficiency of
scintillators, the light-sharing technique is developed. Two
identical trapezoidal monolithic cerium-doped lutetium yttrium
orthosilicate (LYSO) crystals with a bottom size of
25.80 × 25.80 mm2 and a thickness of 20 mm are
optically coupled at one lateral face by an optical medium. The
scintillation light near the optically coupled interface is jointly
collected by two adjacent 8 × 8 SiPM arrays from the bottom
faces. The SiPM signals are individually read out and processed by
using the multichannel readout application-specific integrated
circuits (ASICs) of TOFPET2 to provide a light distribution. The
transverse positions and depth of interaction (DOI) are calculated
from the measured light distribution. As expected, the optical glue
with a refractive index of n = 1.68 shows better light sharing
between two LYSO crystals than the coupling media of silicon grease
(n = 1.40) and air. For the 20 mm thick monolithic LYSO-based PET
detector, the transverse position resolution near the crystal edge
is improved by nearly 30% by using the light-sharing method
compared with the black-painted treatment. However, the DOI
resolution near the edge of the crystal is not significantly
improved, which may be attributed to the incomplete collection of
scintillation light. The DOI resolution of the detector would be
improved by using electronics with lower noise and SiPM arrays with
smaller pixel.
Analysis of sensitivity and formulation of empirical relationship between parameters of FSW process and tensile strength of AZ80A Mg alloy joints
Authors: Gunasekaran J , Sevvel P , Vasanthe Roy J , Sivaramakrishnan A 
Published: May 2023

Abstract
In this research paper, an endeavour was made to devise empirical relations amidst the process parameters of friction stir welding (FSW) and tensile relevant strength of AZ80A Mg alloy joints, based on a 6 parameters—5 levels based central composite design (CCD). Mathematical equations illustrating the impact of process parameters of FSW were formulated based on quadratic regression based analysis to optimize the parameters for attaining superior tensile strength and sensitivity related equations were established from these numerical models. A detailed sensitivity characteristic relevant map for the FSW of AZ80A Mg alloys was established forecasting the fine tuning related prerequisites of the employed FSW parameters. Coefficient of determinant (R2) announced that 99.062% of the overall variability was described by the formulated model and only lower than 1% of the overall variations was not justified by the model. Predicted R2 was also in perfect agreement with the adjusted R2 and announced the model’s capability to demonstrate 95.43% of the variability in the generated data. Highest value of tensile relevant strength (80.77% of the parent metal) was exhibited by the AZ80A Mg alloy joint fabricated under optimized parameters. Tensile relevant strength of AZ80A Mg joints was observed to be highly sensitive to traverse speed of the employed tool.
Realistic mask generation for matter-wave lithography via machine learning
Authors: Fiedler Johannes , Palau Adriá Salvador , Osestad Eivind Kristen , Parviainen Pekka , Holst Bodil 
Published: May 2023

Abstract
Fast production of large-area patterns is crucial for the established semiconductor industry and enables industrial-scale production of next-generation quantum devices. Metastable atom lithography with binary holography masks has been suggested as a higher resolution/low-cost alternative to the current state of the art: extreme ultraviolet lithography. However, it was recently shown that the interaction of the metastable atoms with the mask material (SiN) leads to a strong perturbation of the wavefront, not included in the existing mask generation theory, which is based on classical scalar waves. This means that the inverse problem (creating a mask based on the desired pattern) cannot be solved analytically, even in 1D. Here we present a machine-learning approach to mask generation targeted for metastable atoms. Our algorithm uses a combination of genetic optimisation and deep learning to obtain the mask. A novel deep neural architecture is trained to produce an initial approximation of the mask. This approximation is then used to generate the initial population of the genetic optimisation algorithm that can converge to arbitrary precision. We demonstrate the generation of arbitrary 1D patterns for system dimensions within the Fraunhofer approximation limit.
Efficiency metrics for auditory neuromorphic spike encoding techniques using information theory
Authors: El Ferdaoussi Ahmad , Rouat Jean , Plourde Eric 
Published: May 2023

AbstractSpike encoding of sound consists in converting a sound waveform into spikes. It is of interest in many domains, including the development of audio-based spiking neural network applications, where it is the first and a crucial stage of processing. Many spike encoding techniques exist, but there is no systematic approach to quantitatively evaluate their performance. This work proposes the use of three efficiency metrics based on information theory to solve this problem. The first, coding efficiency, measures the fraction of information that the spikes encode on the amplitude of the input signal. The second, computational efficiency, measures the information encoded subject to abstract computational costs imposed on the algorithmic operations of the spike encoding technique. The third, energy efficiency, measures the actual energy expended in the implementation of a spike encoding task. These three efficiency metrics are used to evaluate the performance of four spike encoding techniques for sound on the encoding of a cochleagram representation of speech data. The spike encoding techniques are: Independent Spike Coding, Send-on-Delta coding, Ben’s Spiker Algorithm, and Leaky Integrate-and-Fire (LIF) coding. The results show that LIF coding has the overall best performance in terms of coding, computational, and energy efficiency.
Estimating the foraging range of Cerceris fumipennis (Hymenoptera: Crabronidae) using land cover data
Authors: Rutledge Claire Elise 
Published: May 2023

Abstract
Biosurveillance monitors the prey of the solitary buprestid-hunting wasp, Cerceris fumipennis (Hymenoptera: Crabronidae), for the presence for emerald ash borer (Agrilus planipennis, Fairmaire: Coleoptera: Buprestidae). Still unresolved is the foraging range, and thus the surveillance range, of C. fumipennis. Foraging occurs in forest canopies and wasps are difficult to track. We assumed that the proportion of conifer-feeding beetles collected at a colony would be related to the proportion of conifers in the surrounding area. If this is the case, the radius of the area around a colony which best correlates the proportion of conifers with the proportion of conifer feeding prey should reflect the foraging range of the colony. In this study, we used 7 yr of foraging data, and the National Land Cover Dataset 2016 map to estimate the foraging range of C. fumipennis. Overall, we found that the highest correlation between prey type collected, and forest type present, was between 1,000 and 1,500 m from the nest sites. We thus conclude that surveillance of a colony of C. fumipennis will yield information about the presence of non-native buprestids within a 1.0–1.5 km radius.