bluuebunny/crossref_metadata_2025_split huggingface dataset:
VMD based trigonometric entropy measure: a simple and effective tool for dynamic degradation monitoring of rolling element bearing
Authors: Kumar Anil , Gandhi C P , Vashishtha Govind , Kundu Pradeep , Tang Hesheng , Glowacz Adam , Shukla Rajendra Kumar , Xiang Jiawei 
Published: November 2021

Abstract
Early identification of rolling element defects is always a topic of interest for researchers and the industry. For early fault identification, a simple and effective dynamic degradation monitoring method using variational mode decomposition (VMD) based trigonometric entropy measure is developed. First, vibration signals are obtained and are further decomposed using VMD to obtain various frequency modes. Second, a trigonometric entropy measure is developed to monitor the dynamic change occurring in the health of bearing. Third, trigonometric entropy measure of various VMD modes is computed. Fourth, the variance of measure is computed and two modes having the highest variance are selected for principal component analysis (PCA). Thereafter, PCA of selected measures is carried out. Finally, dynamic degradation monitoring is carried out by observing the trend in the principal component having the highest diverse information. The testing of newly developed VMD based trigonometric entropy measure is carried out on the two different types of data set. One is from XJTU-SY Bearing datasets and another is from the Centre for Intelligent Maintenance Systems. The experimental study reveals that the proposed method is capable of raising the alarm about the initiation of defects at a very early stage. Compared to existing indicators such as kurtosis, RMS, and Shannon entropy, the proposed method is superior while carrying out defect degradation monitoring.
Development of a dynamic pressure standard of low amplitudes and frequencies
Authors: Díaz Tey Alberto Juan , Govaere Vicarioli Georges 
Published: November 2021

Abstract
The height of the gravitational wave is an influential magnitude in the estimation of its energy content, a very important parameter in the design of maritime structures such as piers and breakwaters; however, there are reasonable doubts among researchers regarding the quality of its measurement. The objective of the present work was to demonstrate that a stationary calibrated pressure transmitter allows the indirect calculation of the wave height with satisfactory accuracy despite the fact that it is a dynamic event as long as its frequency range is low, as is the case with the gravitational waves of the Costa Rican central Pacific Ocean: between 0.05 and 0.39 Hz. In the absence of a primary standard of periodic pressure disturbances, an alternate path was developed based on the characterization of the parameters of the differential equation characteristic of a pressure measurement system in a shock tube prototype from normal shock wave theory and subsequent verification in a periodic disturbance generator that its attenuation and delay are practically negligible at the frequency of 0.1 Hz. The effect of the different geometry of the chamber of the pressure measurement system used in the sea was evaluated pneumatically by comparison with the dynamic pressure standard in the prototype of the periodic disturbance generator, while the effect of the compressibility of the fluid was evaluated in water in the wave channel of the Laboratory of Maritime Engineering, Rivers and Estuaries of the University of Costa Rica. The results show that the pressure measured from the least-squared adjustment coefficients of an electric current transmitter obtained by stationary calibration is acceptable to estimate the climatology of the gravitational wave characteristic of the Costa Rican central Pacific Ocean with maximum errors of 136 mm in waves of height up to 1.4 m.
DOX-loaded silver nanotriangles and photothermal therapy exert a synergistic antibreast cancer effect via ROS/ERK1/2 signaling pathway
Authors: Li Fan , Yang Huiquan , Cao Yuyu , Li Dongdong , Ma Jing , Liu Peidang 
Published: November 2021

Abstract
The combination of multiple therapies has been proved to be more effective than a single therapy for many cancers. This study aimed to investigate the synergistic antibreast cancer effect of doxorubicin-loaded silver nanotriangles (DOX-AgNTs) combined with near-infrared (NIR) irradiation and explore the underlying mechanism. AgNTs were prepared by a chemical method and DOX was loaded via electrostatic adsorption. Characterization was performed by transmission electron microscopy, ultraviolet–visible spectroscopy and dynamic light scattering. The viability of MDA-MB-231 cells was detected by using MTT assay to evaluate the synergistic anticancer effect of DOX-AgNTs combined with NIR irradiation. The intracellular reactive oxygen species (ROS) level and cell apoptosis were analyzed by flow cytometry. Mitochondrial membrane potential (MMP) was measured with fluorescence microscopy. The mechanism was further investigated with ROS scavenger N-acetylcysteine and specific inhibitors of extracellular signal-regulated kinase 1/2 (ERK1/2), C-jun N-terminal kinase and p38 pathways. Characterization results revealed that the prepared AgNTs were mostly triangular and the mean edge length was about 126 nm. The combination of DOX-AgNTs and NIR exhibited a superior synergistic anticancer effect over single DOX-AgNTs or photothermal therapy (PTT). N-acetylcysteine and ERK1/2 inhibitor U0126 were found to significantly rescue the decreased cell viability, declined MMP and increased apoptosis induced by the combined treatment. Our results suggested that DOX-AgNTs combined with PTT performed a synergistic antibreast cancer effect. The synergy might be closely associated with the excessive production of ROS, changed MMP and the activation of ERK1/2 signaling pathway. These findings might provide a new perspective for the development of breast cancer treatments with excellent efficacy.
Asymptotically exact photonic approximations of chiral symmetric topological tight-binding models
Authors: Palmer S , Ignatov Y , Craster R V , Makwana M 
Published: November 2021

Abstract
Topological photonic edge states, protected by chiral symmetry, are attractive for guiding wave energy as they can allow for more robust guiding and greater control of light than alternatives; however, for photonics, chiral symmetry is often broken by long-range interactions. We look to overcome this difficulty by exploiting the topology of networks, consisting of voids and narrow connecting channels, formed by the spaces between closely spaced perfect conductors. In the limit of low frequencies and narrow channels, these void–channel systems have a direct mapping to analogous discrete mass–spring systems in an asymptotically rigorous manner and therefore only have short-range interactions. We demonstrate that topological tight-binding models that are protected by chiral symmetries, such as the SSH model and square-root semimetals, are reproduced for these void–channel networks with appropriate boundary conditions. We anticipate, moving forward, that this paper provides a basis from which to explore continuum photonic topological systems, in an asymptotically exact manner, through the lens of a simplified tight-binding model.
The dominant eigenvector of a noisy quantum state
Authors: Koczor Bálint 
Published: November 2021

Abstract
Although near-term quantum devices have no comprehensive solution for correcting errors, numerous techniques have been proposed for achieving practical value. Two works have recently introduced the very promising error suppression by derangements (ESD) and virtual distillation (VD) techniques. The approach exponentially suppresses errors and ultimately allows one to measure expectation values in the pure state as the dominant eigenvector of the noisy quantum state. Interestingly this dominant eigenvector is, however, different than the ideal computational state and it is the aim of the present work to comprehensively explore the following fundamental question: how significantly different are these two pure states? The motivation for this work is two-fold. First, comprehensively understanding the effect of this coherent mismatch is of fundamental importance for the successful exploitation of noisy quantum devices. As such, the present work rigorously establishes that in practically relevant scenarios the coherent mismatch is exponentially less severe than the incoherent decay of the fidelity—where the latter can be suppressed exponentially via the ESD/VD technique. Second, the above question is closely related to central problems in mathematics, such as bounding eigenvalues of a sum of two matrices (Weyl inequalities)—solving of which was a major breakthrough. The present work can be viewed as a first step towards extending the Weyl inequalities to eigenvectors of a sum of two matrices—and completely resolves this problem for the special case of the considered density matrices.
Anomaly in the electron orbital g-factor: analysis of data on Ar, Ne and He
Authors: Awobode A M 
Published: November 2021

Abstract
Deviations from the exact value 1, of the electron orbital g-factor

g

L

,

are determined from the measured

g

J

ratios of some states of the noble gas atoms He, Ne and Ar. The calculated values are compared with those previously found from the ratio of the Lande g-factors measured on the atoms of In, Ga and Na. The anomalies obtained from some of the rare gas atoms are, at least, one order of magnitude higher, in absolute value, than those from the one-valence-electron atoms. Configuration interactions and perturbations are considered for the atomic states analyzed and are found to be negligible. Thus, the electron’s orbital g-factor appears significantly anomalous. The implications for QED and the structure of the electron are discussed.
Analysis, circuit implementation and synchronization control of a hyperchaotic system
Authors: Yan Shaohui , Wang Ertong , Wang Qiyu , Sun Xi , Ren Yu 
Published: November 2021

Abstract
A four-dimensional autonomous hyperchaotic system is constructed, and the basic characteristics of the system are studied by the power spectrum, Poincaré maps, 0–1 test and Lyapunov exponents. The system has rich dynamical behaviors, such as bursting oscillations, offset boosting, transient chaos, intermittent chaos and coexistence of attractors. In addition, by studying the coexisting phenomenon and spectral entropy (SE) complexity of different initial values, an initial value that is more suitable for chaotic secure communication is selected. The circuit simulation of the system using Multisim and then the actual hardware implementation of the system by Field Programmable Gate Array (FPGA), these prove the practical existence of the system. Finally, combining the methods of backstepping control, multi-switching synchronization and synchronization of different systems, a set of controllers are proposed which can realize the backstepping multi-switching synchronization of this system with a memristive chaotic system.
Multifunctional performance and ferroelectric phase characteristic of BCTH-Eu ceramics prepared by low-temperature sintering via LiBO2 doping
Authors: Fang Bijun , Zhou Yu , Zhang Shanshan , Zhang Shuai , Ding Jianning 
Published: November 2021

Abstract
Multifunctional performance [(Ba0.85Ca0.15)0.995Eu0.005](Ti0.9Hf0.1)O3 (BCTH-Eu) ceramics were prepared by conventional solid-state low-temperature sintering method via LiBO2 doping, in which the sintering aid LiBO2 was introduced into the calcined perovskite precursor powder through liquid phase coating technique. Phase-pure perovskite structure BCTH-Eu ceramics are obtained by the method, and the sintering temperature is decreased about 150 °C as compared with the conventional method whose sintering temperature is normally above 1450 °C. The ceramics present rather high density, uniform distribution of grains and elementals, and have submicron meter grain size. Due to complex substitution of cations at A-site and B-site of the perovskite structure, the LiBO2-doped BCTH-Eu ceramics exhibit displacive driven normal ferroelectrics accompanied by apparent diffused relaxation characteristic. The 1340 °C sintered LiBO2-doped BCTH-Eu ceramics present maximum piezoelectric constant d33 value of 314 pC/N poled under 20 kV cm−1, and the ceramics sintered between 1320 °C–1330 °C exhibit excellent comprehensive electrical properties and multifunctional performance. Such excellent multifunctional properties obtained in this work can be partially attributed to the coexistence of multi-ferroelectric phases, which is confirmed by dielectric response fitting and Raman Gaussian fitting.
Multiscale time-bin analysis of delayed gamma-ray spectra of fission products
Authors: Elmaghraby Elsayed K , Tohamy M , Comsan M N H 
Published: November 2021

Abstract
The present work provides an analysis scheme of delayed gamma-ray spectra based on multiscale time-bin measurements in order to draw conclusions on the association of observed gamma-lines to certain nuclides, especially following the fission process to serve nuclear safeguards and security. The provided time-bin analysis scheme focuses on estimating post-irradiation decays of fission products with interfering gamma-ray lines having energies within the resolution of the used gamma detector. Being a source of deviation, instead of the fixed values of cooling time before each measurement, pinning down the accurate time for each time-bin that should be assigned to each radionuclide in each measurement had been determined independently. This scheme had enabled multiscale of the time-bin analysis ranging from a minute to hours. Experimental measurements were carried out on a natural uranium dioxide sample irradiated in a mixed field of water moderated neutrons. A stable neutron flux from a 5 Ci Am-Be source was used. Results showed great potential for the use of identification and assessment of the contents. The multiscale time-bin analysis scheme was able to resolve the 74 keV gamma-band to obtain the cross-section for 238U(n,γ)239U reaction, the 884.09 keV gamma-line of 134I/ 134Te, the 306.8 keV gamma-line from 101Tc/101Mo, and the 658 keV gamma-line of 97Nb/97Zr. Time-bin analysis showed that 134I, 101Tc, and 97Nb are not, by themselves, primary fission products, but rather they are the daughters of their high-yield parent fission products (134Te, 101Mo, and 97Zr). In the article, the mathematics of the proposed multiscale time-bin analysis is thoroughly outlined.
Axion-photon conversion in strongly magnetised plasmas
Authors: Millar Alexander J. , Baum Sebastian , Lawson Matthew , Marsh M.C. David 
Published: November 2021

Abstract
Axion dark matter can resonantly convert to photons in the magnetosphere of neutron stars, possibly giving rise to radio signals observable on Earth. This method for the indirect detection of axion dark matter has recently received significant attention in the literature. The calculation of the radio signal is complicated by a number of effects; most importantly, the gravitational infall of the axions onto the neutron star accelerates them to semi-relativistic speed, and the neutron star magnetosphere is highly anisotropic. Both of these factors complicate the calculation of the conversion of axions to photons. In this work, we present the first fully three-dimensional calculation of the axion-photon conversion in highly magnetised anisotropic media. Depending on the axion trajectory, this calculation leads to orders-of-magnitude differences in the conversion compared to the simplified one-dimensional calculation used so far in the literature, altering the directionality of the produced photons. Our results will have important implications for the radio signal one would observe in a telescope.
A test of the standard cosmological model with geometry and growth
Authors: Andrade Uendert , Anbajagane Dhayaa , von Marttens Rodrigo , Huterer Dragan , Alcaniz Jailson 
Published: November 2021

Abstract
We perform a general test of the ΛCDM and wCDM cosmological models by comparing constraints on the geometry of the expansion history to those on the growth of structure. Specifically, we split the total matter energy density, Ω
M
, and (for wCDM) dark energy equation of state, w, into two parameters each: one that captures the geometry, and another that captures the growth. We constrain our split models using current cosmological data, including type Ia supernovae, baryon acoustic oscillations, redshift space distortions, gravitational lensing, and cosmic microwave background (CMB) anisotropies. We focus on two tasks: (i) constraining deviations from the standard model, captured by the parameters ΔΩ
M
≡ Ω
M

grow-Ω
M

geom and Δw ≡ w
grow-w
geom, and (ii) investigating whether the S
8 tension between the CMB and weak lensing can be translated into a tension between geometry and growth, i.e. ΔΩ
M
≠ 0, Δw ≠ 0. In both the split ΛCDM and wCDM cases, our results from combining all data are consistent with ΔΩ
M
= 0 and Δ w = 0.
If we omit BAO/RSD data and constrain the split wCDM cosmology, we find the data prefers Δw < 0 at 3.6σ significance and ΔΩ
M
> 0 at 4.2σ evidence.
We also find that for both CMB and weak lensing, ΔΩ
M
and S
8 are correlated, with CMB showing a slightly stronger correlation. The general broadening of the contours in our extended model does alleviate the S
8 tension, but the allowed nonzero values of ΔΩ
M
do not encompass the S
8 values that would point toward a mismatch between geometry and growth as the origin of the tension.
Acausality in superfluid dark matter and MOND-like theories
Authors: Hertzberg Mark P. , Litterer Jacob A. , Shah Neil 
Published: November 2021

Abstract
There has been much interest in novel models of dark matter that exhibit interesting behavior on galactic scales. A primary motivation is the observed Baryonic Tully-Fisher Relation in which the mass of galaxies increases as the quartic power of rotation speed. This scaling is not obviously accounted for by standard cold dark matter. This has prompted the development of dark matter models that exhibit some form of so-called MONDian phenomenology to account for this galactic scaling, while also recovering the success of cold dark matter on large scales. A beautiful example of this are the so-called superfluid dark matter models, in which a complex bosonic field undergoes spontaneous symmetry breaking on galactic scales, entering a superfluid phase with a 3/2 kinetic scaling in the low energy effective theory, that mediates a long-ranged MONDian force. In this work we examine the causality and locality properties of these and other related models. We show that the Lorentz invariant completions of the superfluid models exhibit high energy perturbations that violate global hyperbolicity of the equations of motion in the MOND regime and can be superluminal in other parts of phase space. We also examine a range of alternate models, finding that they also exhibit forms of non-locality.
Low scale leptogenesis and dark matter in the presence of primordial black holes
Authors: Das Suruj Jyoti , Mahanta Devabrat , Borah Debasish 
Published: November 2021

Abstract
We study the possibility of low scale leptogenesis along with dark matter (DM) in the presence of primordial black holes (PBH). For a common setup to study both leptogenesis and DM we consider the minimal scotogenic model which also explains light neutrino mass at radiative level. While PBH in the mass range of 0.1–105 g can, in principle, affect leptogenesis, the required initial PBH fraction usually leads to overproduction of scalar doublet DM whose thermal freeze-out occurs before PBH evaporation. PBH can lead to non-thermal source of leptogenesis as well as dilution of thermally generated lepton asymmetry via entropy injection, with the latter being dominant. The parameter space of scotogenic model which leads to overproduction of baryon or lepton asymmetry in standard cosmology can be made consistent in the presence of PBH with appropriate initial mass and energy fraction. On the other hand, for such PBH parameters, the scalar DM is constrained to be in light mass regime where its freeze-out occurs after PBH evaporation. We then discuss the possibility of fermion singlet DM with N
2 leptogenesis in the same model where due to singlet nature of DM, its connection with PBH parameters and hence leptogenesis becomes stronger compared to the previous case.
Investigation of aerodynamics and heat transfer of the modular jet recuperator
Authors: Alekseev P D , Leukhin Yu L 
Published: November 2021

Abstract
A study of the aerodynamics and heat transfer of a jet modular recuperator with a change in its geometric characteristics has been carried out. The influence of the in-line and staggered arrangement of the blowing holes, as well as the diameter of the perforated pipe is considered. In all considered variants, the number of holes, their diameter and gas flow rate through the recuperator remained unchanged. Numerical modeling of the problem was carried out in a three-dimensional setting using the ANSYS Fluent 15.0 software package. It was found that with the in-line arrangement of the blowing holes, secondary flows are formed between their longitudinal rows in the form of swirling jets of opposite rotation directed towards the outlet section of the recuperative device, through which the main part of the heated air flows out. With the staggered arrangement of the blowing holes, the formation of spiral vortices is disturbed, the air flow is carried out along the entire cross section of the annular channel, increasing the drift effect of the flow on the impact jets, which leads to a decrease in the intensity of heat transfer and its uniformity along the length of the working surface. An increase in the diameter of the inner perforated pipe leads to a decrease in the drift effect of the cocurrent flow on the jets, an increase in the distribution uniformity of the heat flux along the length of the heat transfer surface, and an increase in the heat transfer coefficient.
Numerical simulation of a separated flow in a ribbed channel by the RANS and LES methods
Authors: Barsukov A V , Terekhov V V , Terekhov V I 
Published: November 2021

Abstract
The results of numerical simulation of a turbulent flow in a flat channel in the presence of vortex generators in the form of periodic solid ribs by the RANS and LES method are presented. The Reynolds number calculated by the rib height and the average flow rate is Re = 12600. The influence of the distance between the ribs on the flow structure is investigated. The boundaries of different types of roughness and their influence on the heat transfer intensity are shown.
Heat transfer and skin-friction in a nonequilibrium adverse pressure gradient
Authors: Kiselev N A , Vinogradov Yu A , Zditovets A G 
Published: November 2021

Abstract
The paper presents the results of an experimental study of influence of a weak and moderate nonequilibrium adverse pressure gradient (APG) on the parameters of the dynamic and thermal boundary layers. The Reynolds number based on the momentum thickness at the beginning of the APG region was Re **=5500. The section of the channel with APG was a slotted channel with an opening angle of the upper wall of 0-14°. The values of the relative (referred to the parameters in a zero pressure gradient flow at the same Re **) friction and heat transfer coefficients, as well as the Reynolds analogy factor depending on the longitudinal pressure gradient, are obtained. The values of the relative friction coefficient decreased to cf/cf0
=0.7 and those of the heat transfer to St/St0=0.9. A maximum value of the Reynolds analogy factor (St/St0)/(cf/cf0
)=1.16 was reached for the pressure gradient parameter β=2.9. The ratio of the heat transfer and drag coefficients of the dimpled to smooth surfaces remained approximately constant regardless of the presence or magnitude of a adverse pressure gradient.