Radius Parameter Research Articles

Tailored Porous Transport Layers for Optimal Oxygen Transport in Water Electrolyzers: Combined Stochastic Reconstruction and Lattice Boltzmann Method.

The porous transport layer (PTL) plays an integral role for the mass transport in polymer electrolyte membrane (PEM) electrolyzers. In this work, a stochastic reconstruction method of titanium felt-based PTLs is applied and combined with the Lattice Boltzmann method (LBM). The aim is to parametrically investigate the impact of different PTL structures on the transport of oxygen. The structural characteristics of a reconstructed PTL agree well with experimental investigations. Moreover, the impact of PTL porosity, fiber radius, and anisotropy parameter on the structural characteristics of PTLs are analyzed, and their impact on oxygen transport are elucidated by LBM. Eventually, a customized graded PTL is reconstructed, exhibiting almost optimal mass transport performance for the removal of oxygen. The results show that a higher porosity, larger fiber radius, and smaller anisotropy parameter facilitate the formation of oxygen propagation pathways. By tailoring the fiber characteristics and thus optimizing the PTLs, guidelines for the optimal design and manufacturing can be obtained for large-scale PTLs for electrolyzers.

Identification of Aquifer and Pumped Well Parameters Using the Data Hidden in Non-Linear Losses

During the pumping of wells, the groundwater level drawdown, as measured in the pumped well, is increased by non-linear losses caused by the water flow velocity through the well screens. This undermines the adequacy of the direct use of the measured drawdown data in the well for the purpose of the realistic identification of the effective well radius and aquifer parameters. This anomaly is avoided by reshaping the drawdown function into a function of the specific drawdown sw/Q of the pumped well. This reshaping simplifies the exclusion of non-linear losses from the sequence of measured data of the water level in the well at the position of the effective radius of the pumped well. Combining the data of linear losses and the respective pumping rate of the pumped well, a function of the specific drawdown of the radial flow sw/Q was formed. This function describes the aquifer parameter relations during the respective test pumping. A consistent sequence of the function of the specific drawdown sw/Q of the pumped well reveals the actual value of the coefficient of nonlinear losses. Moreover, the specific drawdown function enables the reliable estimation of aquifer transmissivity using only the pumped well drawdown data.

The Effect of Diffuseness Parameter on the Quasi-Elastic Scattering of the 25Mg + 90Zr and 28Si + (120Sn ,150Nd) Systems using Wood-Saxon Potential

In this research, the effect of changing the values of the diffusion parameter on the semi-elastic scattering ( ) and distribution (D) calculations for (SC) and (CC) have been studied. Three values were taken from the diffusion for each system parameter. It is assumed that the nuclear potential has a Woods-Saxon form, which is indicated by the surface diffuseness, potential depth, and radius parameters for (25Mg + 90Zr), (28Si + (120Sn ,150Nd) Systems. The chi-square (χ2) is applied to compare the best-fitted value of the diffuseness parameter between the theoretical calculations and the experimental data. According to the results of (χ2 ), we noticed that some systems achieved a good match between the theoretical calculations and experimental data of semi-elastic scattering ( ) and the distribution calculations at the standard value of the diffusion parameter (a0=0.63 ) or at a value higher and lower than the standard value. In the case of (SC ) the best fit was at a value less than the standard value of the diffusivity parameter but in the case of (CC ), the fit was better at a value higher than the standard value of the diffusivity parameter because the potential barrier in the (SC ) is single, while in (CC ) calculations it is multiple.

Systematic study of fusion barriers with energy dependent barrier radius

Considering energy dependence of the barrier radius in heavy-ion fusion reactions, a modified Siwek-Wilczyński (MSW) fusion cross section formula is proposed. With the MSW formula, the fusion barrier parameters for 367 reaction systems are systematically extracted, based on 443 datasets of measured cross sections. We find that the fusion excitation functions for about 60% reaction systems can be better described by introducing the energy dependence of the barrier radius which is due to the dynamical effects at energies near and below the barrier. Considering both the influence of the geometry radii and that of the reduced de Broglie wavelength of the colliding nuclei, the barrier heights are well reproduced with only one model parameter. The extracted barrier radius parameters linearly decrease with the effective fissility parameter, and the width of the barrier distribution relates to the barrier height, as well as the reduced de Broglie wavelength at energies around the Coulomb barrier.

Wigner crystallization in quasi-one-dimensional quantum wire

We study the ground-state properties of quasi-one-dimensional paramagnetic electron fluid using variational quantum Monte Carlo method. The electrons are transversally confined using the harmonically regularized Coulomb potential with long range order. In this work we have investigated the crossover from liquid to crystalline phase in the finite width paramagnetic quantum wire. The calculated pair correlation function shows the oscillations of period 2r_text {s} a_0, where a_0 is the Bohr’s radius and r_text {s} is Wigner Seitz radius or electron-density parameter which corresponds to a k=4k_text {F} peak with k_text {F} being Fermi wave vector in the static structure factor at finite electron density. It is a signature of the onset of Wigner crystallization. It is found that the cross-over from liquid to a quasi-Wigner phase is due to enhancement of the electron correlation effects as r_text {s} increases or as the wire width b decreases.

Measurement of the nuclear modification factor of b-jets in 5.02 TeV Pb+Pb collisions with the ATLAS detector

This paper presents a measurement of b-jet production in Pb+Pb and pp collisions at sqrt{s_{_text {NN}}}=5.02 TeV with the ATLAS detector at the LHC. The measurement uses 260 text {pb}^{-1} of pp collisions collected in 2017 and 1.4 text {nb}^{-1} of Pb+Pb collisions collected in 2018. In both collision systems, jets are reconstructed via the anti-k_{t} algorithm. The b-jets are identified from a sample of jets containing muons from the semileptonic decay of b-quarks using template fits of the muon momentum relative to the jet axis. In pp collisions, b-jets are reconstructed for radius parameters R= 0.2 and R= 0.4, and only R= 0.2 jets are used in Pb+Pb collisions. For comparison, inclusive R= 0.2 jets are also measured using 1.7 text {nb}^{-1} of Pb+Pb collisions collected in 2018 and the same pp collision data as the b-jet measurement. The nuclear modification factor, R_text {AA}, is calculated for both b-jets and inclusive jets with R= 0.2 over the transverse momentum range of 80–290 GeV. The nuclear modification factor for b-jets decreases from peripheral to central collisions. The ratio of the b-jet R_text {AA} to inclusive jet R_text {AA} is also presented and suggests that the R_text {AA} for b-jets is larger than that for inclusive jets in central Pb+Pb collisions. The measurements are compared with theoretical calculations and suggest a role for mass and colour-charge effects in partonic energy loss in heavy-ion collisions.

Measurement of substructure-dependent jet suppression in Pb+Pb collisions at 5.02 TeV with the ATLAS detector

The ATLAS detector at the Large Hadron Collider has been used to measure jet substructure modification and suppression in Pb+Pb collisions at a nucleon-nucleon center-of-mass energy $\sqrt{s_{_\mathrm{NN}}}=5.02~\mathrm{TeV}$ in comparison with $pp$ collisions at $\sqrt{s}=5.02~\mathrm{TeV}$. The Pb+Pb data, collected in 2018, have an integrated luminosity of $1.72~\mathrm{nb^{-1}}$, while the $pp$ data, collected in 2017, have an integrated luminosity of $260~\mathrm{pb}^{-1}$. Jets used in this analysis are clustered using the anti-$k_{t}$ algorithm with a radius parameter $R=0.4$. The jet constituents, defined by both tracking and calorimeter information, are used to determine the angular scale $r_\mathrm{g}$ of the first hard splitting inside the jet by reclustering them using the Cambridge-Aachen algorithm and employing the soft-drop grooming technique. The nuclear modification factor, $R_\mathrm{AA}$, used to characterize jet suppression in Pb+Pb collisions, is presented differentially in $r_\mathrm{g}$, jet transverse momentum, and in intervals of collision centrality. The $R_\mathrm{AA}$ value is observed to depend significantly on jet $r_\mathrm{g}$. Jets produced with the largest measured $r_\mathrm{g}$ are found to be twice as suppressed as those with the smallest $r_\mathrm{g}$ in central Pb+Pb collisions. The $R_\mathrm{AA}$ values do not exhibit a strong variation with jet $p_\mathrm{T}$ in any of the $r_\mathrm{g}$ intervals. The $r_\mathrm{g}$ and $p_\mathrm{T}$ dependence of jet $R_\mathrm{AA}$ is qualitatively consistent with a picture of jet quenching arising from coherence and provides the most direct evidence in support of this approach.

Modeling the adhesion of spherical particles on rough surfaces at nanoscale

In this paper, the Van der Waals force acting between a spherical nanoparticle and a surface with random distribution of asperities has been simulated using the Johnson-Kendall-Roberts (JKR) contact mechanics model. To predict the adhesion force in different mediums and under different contact conditions, it is necessary to calculate the adhesion force in micro/nano systems. For this purpose, four different cases of surface roughness have been studied. The geometries of these rough surfaces have been defined taking into account the two key parameters of asperity radius and asperity height, and the necessary equations to determine the contact area and the magnitude of the adhesion force have been derived. Based on the geometries of the surface cap/trough, the interaction force between a spherical nanoparticle and a rough substrate has been obtained by applying Van der Waals theory. Then, the adhesion force for spherical nanoparticle has been modeled with respect to its height above the rough surface. Finally, the behavior of nanoparticles with different radii on four different rough substrates have been simulated and analyzed. The simulation results show that more precise adhesion forces can be obtained by modelling the surface roughness at the nanoscale. For small distances between spherical nanoparticle and the substrate, the adhesion force determined with the new roughness models is larger for rough substrates than for smooth ones.

Multi-response optimization for AISI M7 Hard Turning Using the utility concept

The utility idea is used to optimize AISI M7 hard turning in the present study. This study uses the Taguchi optimization approach to examine the effects of insert nose radius and machining parameters such as cutting speed, feed rate, and depth of cut on surface roughness (Ra) and material removal rate (MRR) in a turning operation. The signal-to-noise (S/N) ratio is used to analyze the performance characteristics in the turning of AISI M7 employing nose radius of 0.4, 0.8, and 1.2 mm carbide inserts on CNC turning centre in a three-level, four-parameter design of experiment using L9 orthogonal array using MINITAB 17. Every trial is held in a dry setting. According to the results of the current investigation, feed rate and nose radius are the most important variables affecting surface roughness and material removal rate.

Influence of combination of coaxial cylindrical explosives on fragmentation and shock waves of a shelled composite charge

AbstractThis paper investigates fragmentation and shock waves generated by a novel coaxial cylindrical composite charge composed of an inner explosive, an intermediate inert material and an outer explosive widely used in tunable ammunition. Charges containing two types of explosive combinations were designed, and explosion experiments were conducted in two initiation modes: detonating only an inner explosive and detonating inner and outer explosives simultaneously. Results suggest the composite charge with higher inner‐detonation velocity and lower outer‐detonation velocity achieves more differentiated power output under different initiations. The differences in the average fragment mass and peak overpressure are as high as 34.5 % and 39.9 %, respectively, which are larger than 4.4 % and 8.4 % under the contrary explosive combination. On the basis of this observation, corresponding 2‐D and 3‐D models were simulated using AUTODYN code to investigate the evolution of the detonation waveform and detonation energy release. The numerically simulated initial shell expansion and later shock wave propagation of the composite charge agreed well with the experimental data. The errors in expansion radius and shock wave parameters (peak overpressure and specific impulse) are less than 6.6 % and 16.9 %, respectively, between the simulations and experiments. It was found that the particle velocity profile in the charge with lower outer‐detonation velocity lagged behind that of the charge with higher inner‐detonation velocity under inner initiation, while a wave front collision zone close to the outer charge appeared in the non‐detonation layer under simultaneous initiation.

Dynamic radius jet clustering algorithm

The study of standard QCD jets produced along with fat jets, which may appear as a result of the decay of a heavy particle, has become an essential part of collider studies. Current jet clustering algorithms, which use a fixed radius parameter for the formation of jets from the hadrons of an event, may be inadequate to capture the differing radius features. In this work, we develop an alternative jet clustering algorithm that allows the radius to vary dynamically based on local kinematics and distribution in the η-ϕ plane inside each evolving jet. We present the usefulness of this dynamic radius clustering algorithm through two Standard Model processes, and thereafter illustrate it for a scenario beyond the Standard Model at the 13 TeV LHC.

Estimations of Planetary Occurrence Rates for Solar-type Stars with Data Release 25 from Kepler Q1–Q17 Observations

The detection of exoplanets in the past three decades has revealed the fact that planets are ubiquitous in the universe. In order to deeply study the ubiquity of habitable planets, on one hand, we need to understand the characteristics of habitable planets; on the other hand, we can analyze the the distribution characteristics of exoplanets have been found, and to calculate the probability of occurrence of such planets around stars. Among the exoplanets that have been found so far, most of them are discovered by the transit method. For example, the number of the planets detected by the Kepler space telescope is 2344. Kepler telescope officially retired in 2018, and the Kepler team released the final version of Kepler Data Release (DR25), including a total of 198709 stars observed quarterly Q1–Q17. Here we analyze the Kepler data by using two different methods, Inverse Detection Efficiency Method (IDEM) and Maximum Likelihood Analysis (ML), to estimate planet occurrence rates in the space of the parameters of radius and orbital period. At the same time, the samples were classified according to the spectral types of stars, and the planet occurrence rates around F, G, and K Kepler stars as well as its overall formation rate were estimated respectively. We estimate the planetary occurrence rates for planets among radius range of 1–20 R⊕ (R⊕ is one radius of the Earth) and orbital period range of 0.4–400 days by IDEM and ML, for which around F stars are respectively 0.36±0.02 and 0.47±0.02. The rates around G stars by IDEM and ML are respectively 1.62±0.05 and 1.23±0.04. The rates around K stars by IDEM and ML are respectively 2.61±0.12 and 2.73±0.13. And the overall occurrence rate of such planets around F, G, K stars by IDEM and ML are respectively 1.16±0.03 and 0.90±0.02. According to our estimation, we further show the results for the planet occurrence rates around stars with different spectral types by different methods, and discuss the reliability of the results in comparison with the previous studies.

The EBLM project X. Benchmark masses, radii, and temperatures for two fully convective M-dwarfs using K2

ABSTRACT M-dwarfs are the most abundant stars in the galaxy and popular targets for exoplanet searches. However, their intrinsic faintness and complex spectra inhibit precise characterization. We only know of dozens of M-dwarfs with fundamental parameters of mass, radius, and effective temperature characterized to better than a few per cent. Eclipsing binaries remain the most robust means of stellar characterization. Here we present two targets from the Eclipsing Binary Low Mass (EBLM) survey that were observed with K2: EBLM J0055-00 and EBLM J2217-04. Combined with HARPS and CORALIE spectroscopy, we measure M-dwarf masses with precisions better than 5 per cent, radii better than 3 per cent, and effective temperatures on order 1 per cent. However, our fits require invoking a model to derive parameters for the primary star and fitting the M-dwarf using the transit and radial velocity observations. By investigating three popular stellar models, we determine that the model uncertainty in the primary star is of similar magnitude to the statistical uncertainty in the model fits of the secondary M-dwarf. Therefore, whilst these can be considered benchmark M-dwarfs, we caution the community to consider model uncertainty when pushing the limits of precise stellar characterization.

Development and test of highly accurate endpoint free energy methods. 1: Evaluation of ABCG2 charge model on solvation free energy prediction and optimization of atom radii suitable for more accurate solvationfreeenergy prediction by the PBSA method.

Accurate estimation of solvation free energy (SFE) lays the foundation for accurate prediction of binding free energy. The Poisson-Boltzmann (PB) or generalized Born (GB) combined with surface area (SA) continuum solvation method (PBSA and GBSA) have been widely used in SFE calculations because they can achieve good balance between accuracy and efficiency. However, the accuracy of these methods can be affected by several factors such as the charge models, polar and nonpolar SFE calculation methods and the atom radii used in the calculation. In this work, the performance of the ABCG2 (AM1-BCC-GAFF2) charge model as well as other two charge models, that is, RESP (Restrained Electrostatic Potential) and AM1-BCC (Austin Model 1-bond charge corrections), on the SFE prediction of 544 small molecules in water by PBSA/GBSA was evaluated. In order to improve the performance of the PBSA prediction based on the ABCG2 charge, we further explored the influence of atom radii on the prediction accuracy and yielded a set of atom radius parameters for more accurate SFE prediction using PBSA based on the ABCG2/GAFF2 by reproducing the thermodynamic integration (TI) calculation results. The PB radius parameters of carbon, oxygen, sulfur, phosphorus, chloride, bromide and iodine, were adjusted. New atom types, on, oi, hn1, hn2, hn3, were introduced to further improve the fitting performance. Then, we tuned the parameters in the nonpolar SFE model using the experimental SFE data and the PB calculation results. By adopting the new radius parameters and new nonpolar SFE model, the root mean square error (RMSE) of the SFE calculation for the 544 molecules decreased from 2.38 to 1.05 kcal/mol. Finally, the new radius parameters were applied in the prediction of protein-ligand binding free energies using the MM-PBSA method. For the eight systems tested, we could observe higher correlation between the experiment data and calculation results and smaller prediction errors for the absolute binding free energies, demonstrating that our new radius parameters can improve the free energy calculation using the MM-PBSA method.

Online tracking and prediction of slip ring degradation using chaos theory based on LSTM neural network

The online monitoring of the slip ring is important for ensuring normal operations of wind turbine equipment. A current-carrying friction experiment was conducted to simulate the degradation process of the slip ring. The chaotic parameter enclosing the radius and statistical parameter root mean square (RMS) were used to characterize the multi-sensor signals comprehensively. A new health indicator (HI) was proposed to evaluate the degradation state of slip rings based on long- and short-term memory neural networks. It was fused by the signals of friction vibration, friction torque, voltage and electric current. The HI presents a better prediction effect by the prediction model. At the severe stage of the slip ring, the evaluation criteria mean absolute error, root mean square error and mean percentage error of the HI were 0.0306, 0.0323 and 5.0225% respectively. These values are much better than the RMS of the vibration signal. The results verify that the method can effectively determine the real-time degradation state of the slip ring.

Study structural, surface morphological and magnetic properties of Mn(1-x) Znx Fe2O4 by solid state reaction method

The powder of Mn-Zn ferrite having the chemical formula Mn(1-x)ZnxFe2O4 where x varies from 0, 0.1, 0.2, 0.3, 0.4, and 0.5 were synthesized by solid state Reaction method. The X-Ray Diffraction studies confirm the formation of spinel cubic structure. The particle size was calculated by X-ray broadening studies. Also the structural parameters like Lattice Constant, X-ray density, bulk density (d), Porosity (P), ionic radius (Ra , Rb) and anion parameter or the oxygen positional parameter for all the samples. The micro structural features of the samples were obtained using a Scanning Electron Microscopy (SEM). The magnetic properties of Mn(1-x)ZnxFe2O4 ferrites were strongly affected by the Zn content. The saturation magnetization increased. It may be due to relatively high orbital contribution of Mn2+ ions to magnetic moment, which gives large induced anisotropy.

GALFIT-ing AGN Host Galaxies in COSMOS: HST versus Subaru

The COSMOS field has been extensively observed by most major telescopes, including Chandra, HST, and Subaru. HST imaging boasts very high spatial resolution and is used extensively in morphological studies of distant galaxies. Subaru provides lower spatial resolution imaging than HST but a substantially wider field of view with greater sensitivity. Both telescopes provide near-infrared imaging of COSMOS. Successful morphological fitting of Subaru data would allow us to measure morphologies of over 104 known active galactic nucleus (AGN) hosts, accessible through Subaru wide-field surveys, currently not covered by HST. The morphological parameters indicate the types of galaxies that host AGNs. For 4016 AGNs between 0.03 < z < 6.5, we study the morphology of their galaxy hosts using GALFIT, fitting components representing the AGN and host galaxy simultaneously using the i-band imaging from both HST and Subaru. Comparing the fits for the differing telescope spatial resolutions and image signal-to-noise ratios, we identify parameter regimes for which there is strong disagreement between distributions of fitted parameters for HST and Subaru. In particular, the Sérsic index values strongly disagree between the two sets of data, including sources at lower redshifts. In contrast, the measured magnitude and radius parameters show reasonable agreement. Additionally, large variations in the Sérsic index have little effect on the of each fit, whereas variations in other parameters have a more significant effect. These results indicate that the Sérsic index distributions of high-redshift galaxies that host AGNs imaged at ground-based spatial resolution are not reliable indicators of galaxy type and should be interpreted with caution.

Photon orbits and phase transition for non-linear charged anti-de Sitter black holes

In this work, we investigate the relation between the photon sphere radius and the first-order phase transition for the charged Einstein-power-Yang-Mills AdS black hole. Through the analysis, we find with a certain condition there exist the non-monotonic behaviors between the photon sphere radius, the impact parameter, the non-linear Yang-Mills charge parameter, temperature, and pressure. And both the changes of photon sphere radius and impact parameter before and after phase transition can be regarded as the order parameter, their critical exponents near the critical point are equal to the same value 1/2, just like the ordinary thermal systems. These indicate that there maybe exists a universal relation of gravity nearby the critical point for a black hole thermodynamical system. Furthermore, the effect of impact parameter on the deflect angle is also investigated.

The influence of physical and algorithmic factors on simulated far-field waveforms and source–time functions of underground explosions using unsupervised machine learning

SUMMARY Characterizing explosion sources and differentiating between earthquake and underground explosions using distributed seismic networks becomes non-trivial when explosions are detonated in cavities or heterogeneous ground material. Moreover, there is little understanding of how changes in subsurface physical properties affect the far-field waveforms we record and use to infer information about the source. Simulations of underground explosions and the resultant ground motions can be a powerful tool to systematically explore how different subsurface properties affect far-field waveform features, but there are added variables that arise from how we choose to model the explosions that can confound interpretation. To assess how both subsurface properties and algorithmic choices affect the seismic wavefield and the estimated source functions, we ran a series of 2-D axisymmetric non-linear numerical explosion experiments and wave propagation simulations that explore a wide array of parameters. We then inverted the synthetic far-field waveform data using a linear inversion scheme to estimate source–time functions (STFs) for each simulation case. We applied principal component analysis (PCA), an unsupervised machine learning method, to both the far-field waveforms and STFs to identify the most important factors that control variance in the waveform data and differences between cases. For the far-field waveforms, the largest variance occurs in the shallower radial receiver channels in the 0–50 Hz frequency band. For the STFs, both peak amplitude and rise times across different frequencies contribute to the variance. We find that the ground equation of state (i.e. lithology and rheology) and the explosion emplacement conditions (i.e. tamped versus cavity) have the greatest effect on the variance of the far-field waveforms and STFs, with the ground yield strength and fracture pressure being secondary factors. Differences in the PCA results between the far-field waveforms and STFs could possibly be due to near-field non-linearities of the source that are not accounted for in the estimation of STFs and could be associated with yield strength, fracture pressure, cavity radius and cavity shape parameters. Other algorithmic parameters are found to be less important and cause less variance in both the far-field waveforms and STFs, meaning algorithmic choices in how we model explosions are less important, which is encouraging for the further use of explosion simulations to study how physical Earth properties affect seismic waveform features and estimated STFs.

Radiological measurement parameters of distal radius and wrist measured on X-rays in the Turkish population.

The aim of our study was to analyze the radiologic morphometry of the distal radius and wrist to assess acceptable limits for restoring normal wrist function after fracture. Radiological measurement parameters were measured retrospectively on anteroposterior and lateral (LAT) wrist radiographs (n=981). Radiological measurement parameters were volar tilt, radial inclination, radial height, ulnar variance, radiocarpal angle, and volar angulation angle. The patients' age, gender, and side of the radiograph were recorded as demographic data. The mean volar tilt angle was 15.4±4.3 degrees. The mean radial inclination angle in males was 26.8±3.6 degrees. The mean radial height was 13.6±2.1 mm. The mean ulnar variance was 0.8±1.9 mm. One hundred and eighty-nine patients had negative ulnar variances. The mean radiocarpal angle was 12.3±2.7. The mean volar angulation angle was 32.1±6.9 degrees. Radial height was found to be positively correlated with radial inclination (p<0.001; r: 601), but it was not significantly correlated with ulnar variance (p=0.14). Distal radius fractures are one of the most common types of fractures. Radiological measurement parameters were used in the determination and follow-up of the treatment. The values obtained in this study belong to the Turkish population. These values may be used as reference values in determining the quality of reduction after fracture and in the design of suitable implants for fracture treatment.