bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamental physics with ESPRESSO: Constraining a simple parametrisation for varying α
Authors: da Fonseca Vitor , Barreiro Tiago , Nunes Nelson J. , Cristiani Stefano , Cupani Guido , D’Odorico Valentina , Leite Ana C. O. , Marques Catarina M. J. , Martins Carlos J. A. P. , Milaković Dinko , Molaro Paolo , Murphy Michael T. , Schmidt Tobias M. , Abreu Manuel , Adibekyan Vardan , Cabral Alexandre , Di Marcantonio Paolo , González Hernández Jonay I. , Palle Enric , Pepe Francesco A. , Rebolo Rafael , Santos Nuno C. , Sousa Sérgio G. , Sozzetti Alessandro , Mascareño Alejandro Suárez , Osorio Maria-Rosa Zapatero
Published: July 2022

Context. The spectrograph ESPRESSO recently obtained a limit on the variation of the fine-structure constant, α, through measurements along the line of sight of a bright quasar with a precision of 1.36 ppm at 1σ level. This imposes new constraints on cosmological models with a varying α. We assume such a model where the electromagnetic sector is coupled to a scalar field dark energy responsible for the current acceleration of the Universe. We parametrise the variation of α with two extra parameters, one defining the cosmological evolution of the quintessence component and the other fixing the coupling with the electromagnetic field.

Aims. The objective of this work is to constrain these parameters with both astrophysical and local probes. We also carried out a comparative analysis of how each data probe may constrain our parametrisation.

Methods. We performed a Bayesian analysis by comparing the predictions of the model with observations. The astrophysical datasets are composed of quasar spectra measurements, including the latest ESPRESSO data point, as well as Planck observations of the cosmic microwave background. We combined these with local results from atomic clocks and the MICROSCOPE experiment.

Results. The constraints placed on the quintessence parameter are consistent with a null variation of the field, and are therefore compatible with a ΛCDM cosmology. The constraints on the coupling to the electromagnetic sector are dominated by the Eötvös parameter local bound.

Conclusions. More precise measurements with ESPRESSO will be extremely important to study the cosmological evolution of α as it probes an interval of redshift not accessible to other types of observations. However, for this particular model, current available data favour a null variation of α resulting mostly from the strong MICROSCOPE limits.
GJ 3090 b: one of the most favourable mini-Neptune for atmospheric characterisation
Authors: Almenara J. M. , Bonfils X. , Otegi J. F. , Attia O. , Turbet M. , Astudillo-Defru N. , Collins K. A. , Polanski A. S. , Bourrier V. , Hellier C. , Ziegler C. , Bouchy F. , Briceno C. , Charbonneau D. , Cointepas M. , Collins K. I. , Crossfield I. , Delfosse X. , Diaz R. F. , Dorn C. , Doty J. P. , Forveille T. , Gaisné G. , Gan T. , Helled R. , Hesse K. , Jenkins J. M. , Jensen E. L. N. , Latham D. W. , Law N. , Mann A. W. , Mao S. , McLean B. , Murgas F. , Myers G. , Seager S. , Shporer A. , Tan T. G. , Twicken J. D. , Winn J.
Published: July 2022

We report the detection of GJ 3090 b (TOI-177.01), a mini-Neptune on a 2.9-day orbit transiting a bright (K = 7.3 mag) M2 dwarf located at 22 pc. The planet was identified by the Transiting Exoplanet Survey Satellite and was confirmed with the High Accuracy Radial velocity Planet Searcher radial velocities. Seeing-limited photometry and speckle imaging rule out nearby eclipsing binaries. Additional transits were observed with the LCOGT, Spitzer, and ExTrA telescopes. We characterise the star to have a mass of 0.519 ± 0.013 M⊙ and a radius of 0.516 ± 0.016 R⊙. We modelled the transit light curves and radial velocity measurements and obtained a planetary mass of 3.34 ± 0.72 ME, a radius of 2.13 ± 0.11 RE, and a mean density of 1.89−0.45+0.52 g cm−3. The low density of the planet implies the presence of volatiles, and its radius and insolation place it immediately above the radius valley at the lower end of the mini-Neptune cluster. A coupled atmospheric and dynamical evolution analysis of the planet is inconsistent with a pure H–He atmosphere and favours a heavy mean molecular weight atmosphere. The transmission spectroscopy metric of 221−46+66 means that GJ 3090 b is the second or third most favorable mini-Neptune after GJ 1214 b whose atmosphere may be characterised. At almost half the mass of GJ 1214 b, GJ 3090 b is an excellent probe of the edge of the transition between super-Earths and mini-Neptunes. We identify an additional signal in the radial velocity data that we attribute to a planet candidate with an orbital period of 13 days and a mass of 17.1−3.2+8.9 ME, whose transits are not detected.
Hot subdwarfs in close binaries observed from space
Authors: Schaffenroth V. , Pelisoli I. , Barlow B. N. , Geier S. , Kupfer T.
Published: July 2022

Context. About a third of the hot subdwarfs of spectral type B (sdBs), which are mostly core-helium-burning objects on the extreme horizontal branch, are found in close binaries with cool, low-mass stellar, substellar, or white dwarf companions. They can show light variations due to different phenomena.

Aims. Many hot subdwarfs now have space-based light curves with a high signal-to-noise ratio available. We used light curves from the Transiting Exoplanet Survey Satellite and the K2 space mission to look for more sdB binaries. Their light curves can be used to study the hot subdwarf primaries and their companions, and obtained orbital, atmospheric, and absolute parameters for those systems, when combined with other analysis methods.

Methods. By classifying the light variations and combining these with the fit of the spectral energy distribution, the distance derived by the parallaxes obtained by Gaia, and the atmospheric parameters, mainly from the literature, we could derive the nature of the primaries and secondaries in 122 (75%) of the known sdB binaries and 82 newly found reflection effect systems. We derived absolute masses, radii, and luminosities for a total of 39 hot subdwarfs with cool, low-mass companions, as well 29 known and newly found sdBs with white dwarf companions.

Results. The mass distribution of hot subdwarfs with cool, low-mass stellar and substellar companions, differs from those with white dwarf companions, implying they come from different populations. By comparing the period and minimum companion mass distributions, we find that the reflection effect systems all have M dwarf or brown dwarf companions, and that there seem to be several different populations of hot subdwarfs with white dwarf binaries – one with white dwarf minimum masses around 0.4 M⊙, one with longer periods and minimum companion masses up to 0.6 M⊙, and at the shortest period, another with white dwarf minimum masses around 0.8 M⊙. We also derive the first orbital period distribution for hot subdwarfs with cool, low-mass stellar or substellar systems selected from light variations instead of radial velocity variations. It shows a narrower period distribution, from 1.5 h to 35 h, compared to the distribution of hot subdwarfs with white dwarfs, which ranges from 1 h to 30 days. These period distributions can be used to constrain the previous common-envelope phase.
Mechanical male sterilisation in invasive signal crayfish Pacifastacus leniusculus: persistence and functionality in captive and wild conditions
Authors: Green Nicky , Andreou Demetra , Bentley Matt , Stebbing Paul , Hart Aaron , Britton J. Robert
Published: July 2022

Management control methods for invasive crayfish remain of limited effectiveness, resulting in ongoing invasions of high ecological impact. As management programmes integrating methods to limit juvenile recruitment could reduce population abundances, the efficacy of a sterile male release technique (SMRT) based on the manual removal of male gonopods was tested here in captive and wild conditions by comparing the survival, gonopod regeneration rates and a range of reproductive metrics of sterilised versus non-sterilised males. Sterilised male survival was high, with their removed gonopods regenerating at sizes that were always smaller than those of non-sterilised males. In captive trials, while sterilised males showed significantly lower areas of spermatophore cover than non-sterilised, and less accuracy in placement, subsequent female brood size did not differ significantly between the two male groups. The number of females retaining their clutches also did not also differ significantly between these groups. Over a seven-year period in the wild, there was no evidence suggesting SMRT significantly reduced female brood sizes and clutch retention rates. Although mechanical SMRT altered the size and delivery accuracy of sterilised male gonopods, female reproductive success of invasive crayfish was unaffected. Several potential reasons for this failure of the technique were identified and require further research.
Overlooked keystone species in conservation plans of fluvial ecosystems in Southeast Europe: a review of native freshwater crayfish species
Authors: Danilović Milan , Maguire Ivana , Füreder Leopold
Published: July 2022

Although a large number of rivers stretches in Southeast Europe (SEE) have a pristine status compared to the rest of Europe, these ecosystems and their freshwater biodiversity are perceptibly threatened. Since crayfish species are known to cover a wide spectrum of ecological functions they are considered as keystone species and ecosystem engineers. Therefore, their decline may substantially impair local biodiversity and ecosystem services. In this manuscript we present a brief overview of the status of the native freshwater crayfish and their habitats in SEE. Different forms of physical habitat degradation as well as invasive alien crayfish species and their pathogens (e.g., Aphanomyces astaci) are simultaneously threatening endangered populations all over SEE. Even though all native crayfish species are listed in the IUCN Red List, so far none of the 33 LIFE rehabilitation projects performed in SEE, has crayfish as target species in their agenda. Furthermore, SEE countries rarely designated Natura 2000 sites for native crayfish. We propose future studies to assess the distribution and functional role of crayfish species in SEE, as well as to develop habitat suitability models for these species during future conservation projects.
Heading towards democratic and sustainable electricity systems – the example of Austria
Authors: Haas Reinhard , Auer Hans , Resch Gustav
Published: July 2022

In recent years rising quantities of electricity generated from new variable renewable energy sources (VRES) have influenced the structure of electricity markets in many countries. The major aim of this work is to investigate the conditions required to head towards a sustainable and more democratic electricity supply system by using even higher amounts of VRES for the example of Austria. The most important result of this investigation is that an approach based on market principles – including flexibility and the final customers – is favourable and will ensure that competition at the service level rather than capacity payments will be the basis for future market designs of the electricity system. The transformation towards a sustainable and more democratic as well as increasingly competitive future electricity supply system is likely to be based on different paradigms of “new thinking”. This means that the fundamental structures of the overall electricity system will change. It will be based on changing from the old inflexible one-way electricity delivery system to a very flexible one with a two or multi-way flow of electricity. Regarding the case study of the Austrian electricity system the major finding is that up to 2030 RES can contribute to electricity generation to the same extent as electricity demand is expected to be. This implies a growth to about 16 TWh Wind (in 2020: 7 TWh) and 12 TWh PV (in 2020: 1 TWh). However, to meet demand on an hourly base over the whole year even after having implemented additional storage capacities and several flexibility measures on the demand-side an amount of about 2 TWh electricity (compared to 10 TWh in 2019) has to be generated from different gas-based power plants (e.g. natural or biomass-based gases).
Die senile Katarakt
Authors: Neuhann Irmingard , Neuhann Lukas , Neuhann Thomas
Published: July 2022

Die Vorstellung der alten Griechen war, dass eine trübe Flüssigkeit über das Auge herabrinne – daher die vom Verb καταρρηγνυναι = herabfließen hergeleitete Bezeichnung. Diese Auffassung zur
Pathophysiologie der Katarakt hat sich heute grundlegend geändert.
Growth of MoS2 films: High-quality monolayered and multilayered material
Authors: Aleithan Shrouq H. , Al-Amer Kawther , Alhashem Zakia , Alati Nada A. , Alabbad Zainab H. , Alam Khan
Published: July 2022

Transition-metal-dichalcogenide materials (TMDs) are proceeding toward future nanoelectronic devices as comprehensive research in this domain proves their extraordinary properties and potential for application in diverse fields. There are associated challenges related to the quality of grown material, grain size, and adaptiveness to a selected substrate, and chemical vapor deposition is considered the ideal technique in these regards. Salt-assisted growth of two-dimensional TMDs has recently solved some growth issues associated with the high melting points of some oxides and the low vapor pressure, which leads to limitations in the growth area. In the current study, NaCl-assisted growth is used to produce high-quality monolayered films on Si/SiO2 and multilayered films of MoS2 on fluorine-doped tin oxide. An empirical methodology was used to determine optimal conditions for sample growth. Factors such as precursor weights and ratios, temperature, and sulfurization were investigated with respect to preparing samples for exploitable applications.
Indirect inverse flux mapping of a concentrated solar source using infrared imaging
Authors: Abuseada Mostafa , Alghfeli Abdalla , Fisher Timothy S.
Published: July 2022

With the growing interest in high-flux solar sources, a need exists for simple, accurate, and inexpensive strategies to characterize their output radiative flux. In this paper, the irradiation output from a 10 kWe xenon lamp solar simulator is characterized by an inverse mapping technique that uses a custom radiometer and infrared camera, validated by a direct characterization method (heat flux gauge). The heat flux distribution is determined in a vacuum chamber using an easily obtainable graphite target and an inverse heat transfer model. The solar simulator produces peak fluxes in the range of 1.5–4.5 MW/m2 as measured directly by a heat flux gauge, and its output can be controlled using a variable power supply. Spectral measurements indicate that minor variations in the simulator’s output with respect to its current supply occur in the spectral range of 450–800 nm. The radiometer presented in this work allows for characterizing solar irradiation under practical conditions (e.g., inside a solar reactor) and thus accounts for deviations due to additional components, such as viewport effects. Additionally, it provides an inexpensive and efficient means of monitoring any deterioration in the performance of solar sources over time without the need for complex recalibration.
Majorana bound states with chiral magnetic textures
Authors: Güngördü Utkan , Kovalev Alexey A.
Published: July 2022

The aim of this Tutorial is to give a pedagogical introduction into realizations of Majorana fermions, usually termed as Majorana bound states (MBSs), in condensed matter systems with magnetic textures. We begin by considering the Kitaev chain model of “spinless” fermions and show how two “half” fermions can appear at chain ends due to interactions. By considering this model and its two-dimensional generalization, we emphasize intricate relation between topological superconductivity and possible realizations of MBS. We further discuss how “spinless” fermions can be realized in more physical systems, e.g., by employing the spin-momentum locking. Next, we demonstrate how magnetic textures can be used to induce synthetic or fictitious spin–orbit interactions, and, thus, stabilize MBS. We describe a general approach that works for arbitrary textures and apply it to skyrmions. We show how MBS can be stabilized by elongated skyrmions, certain higher order skyrmions, and chains of skyrmions. We also discuss how braiding operations can be performed with MBS stabilized on magnetic skyrmions. This Tutorial is aimed at students at the graduate level.
Effects of obstacles on shock-induced perturbation growth
Authors: Wang Hui , Wang He , Zhai Zhigang , Luo Xisheng
Published: July 2022

Effects of obstacles on interface evolution and mixing width induced by Richtmyer–Meshkov instability are investigated experimentally and numerically. In the experiment, the soap film technique is adopted to create an initial interface whose shape is governed by constraint strips protruding into the flow field. By varying the heights of constraint strips protruding into the flow field, effects of obstacles on post-shock flow features are highlighted. First, the interaction of a planar shock with an unperturbed interface is investigated numerically and experimentally. The results show that the obstacles have negligible effects on the transmitted shock velocity, but they greatly increase the reflected shock velocity. The obstacles induce the non-uniform pressure and velocity fields behind the shock, which change the interface evolution and mixing width. Then, experiments of planar shock wave interacting with single-mode interfaces with different initial amplitudes are performed. Induced by the non-uniform post-shock flow, the experimental schlieren images indicate that the spike tip becomes flat, but its size increases in the spanwise direction and the volume of the bubble is reduced. The effects of obstacles are magnified as their heights increase and are more pronounced when the initial interface amplitudes are small. The linear and nonlinear growth rates obtained from experiments show that the obstacles inhibit the perturbation growth, which is partially caused by less kinetic energy the interface obtains from the shock due to the block by the obstacles.
The deuteron NMR Hahn echo decay in polyethylene oxide melts
Authors: Lindt K. , Mattea C. , Stapf S. , Ostrovskaya I. K. , Fatkullin N. F.
Published: July 2022

The deuteron transverse relaxation properties of polyethylene oxide melts of four different molecular weights, covering the range from the onset of entanglements to the regime of fully entangled chains, are investigated using Hahn echo decays over an extensive time interval up to ten times the effective transverse spin relaxation time. The results are compared to predictions based on the Rouse and reptation formalisms, taking into account the dynamical heterogeneity of linear polymer chains produced by the end segments. The experimental results can be described qualitatively by a combination of both models, with the contribution of reptation dynamics increasing with growing chain length. The transition is continuous, rather than being characterized by sharp regime boundaries. Up to a molecular weight of 300.000 g/mol, the predicted limit of pure reptation dynamics is not yet reached. Quantitative deviations from the predicted decays as computed by numerical procedures become observable toward the long-time limit of the Hahn echo decays and are being discussed in terms of shortcomings of the available reptation theories.
A cold cesium beam source based on a two-dimensional magneto-optical trap
Authors: Xie Weibin , Wang Qing , He Xuan , Fang Shengwei , Yuan Zhichao , Qi Xianghui , Chen Xuzong
Published: July 2022

A beam source is proposed for the production of an intense cold cesium atomic beam that can be used in cesium beam atomic clocks. The source is based on a two-dimensional magneto-optical trap (2D-MOT), but introduces hollow cooling and pushing lights in the axial direction to create a 2D+-MOT, which separates the cooling and pushing functions while the low-power pushing light pushes atoms out to form a cold atomic beam. This cold cesium atomic beam source reduces the light shift due to leakage light and retains longitudinal cooling to increase the flux of the cold atomic beam compared with that of the conventional 2D+-MOT scheme. The specifics of the design are investigated, the atomic velocity and beam flux are calculated, and the results are experimentally verified. The results demonstrate that when the power of the pushing light is 180 µW and when its frequency resonates with the 4 → 5′ transition of the Cs D2 line, the most probable longitudinal velocity of the outgoing cold atomic beam, the width of velocity distribution, and the atomic beam flux are 19.38 m/s, 8.1 m/s, and 1.7 × 1010 atoms/s, respectively.
Transverse magnetic electromagnetic mode analysis with electron beam effect in overmoded waveguide of coaxial magnetic wiggler
Authors: Qiang Lanpeng , Luo Wei , Zhang Jianwei , Teng Yan , Li Yongdong , Wang Yue , Wang Hongguang
Published: July 2022

The coaxial wiggler with periodic permanent magnet is one of the ways to realize portable and practical high power microwave, which has a relatively small volume and low weight. However, the electromagnetic mode competition will significantly affect the output power at a high electron current. Based on the dispersion curve considering the effect of the electron beam, we propose a method of judging whether the mode can oscillate as the main mode in the coaxial magnetic wiggler. We analyze the wave–beam interaction by the first-order perturbation and predict some modes that seem impossible in traditional methods. It is verified by 3D particle-in-cell simulation that these electromagnetic modes will be the operating modes.
Computational turbulent flow characteristics in a centrifugal pump
Authors: Bai Yongming , Appiah Desmond , Tao Yi
Published: July 2022

This investigation provides the 3D numerical simulations of a six-blade centrifugal pump that is commonly applied in agriculture and food processing sectors. The simulations were carried out using the unsteady Reynolds averaged Navier–Stokes equations. The k-omega turbulence model was used as a closure for the equations. The velocity and pressure flow fields were used to predict the turbulent flows in the pump under three different operating conditions (part-load 0.8Qd, design 1.0 Qd, and overload 1.2 Qd). The omega vortex identification criterion was further applied to visualize the coherent vortex structures in the impeller and volute at the investigated flow conditions. The impeller eye was characterized with the lowest static pressure fields causing this region to be highly susceptible to cavitation under all flow conditions. At the design point, the velocity vectors were orderly patterned along the blade flow curvature. However, flow separation occurred around the leading edge mainly due to the fact that the flow is non-tangential to the leading edge of the blade as a result of the unsteady effect developed upstream. In conclusion, it can be confirmed that the volute geometry is highly sensitive to the evolution and formation of vortices as revealed by the omega vortex criterion. This work reveals that the design of the volute geometry should be further improved to mitigate unsteady flow losses. Again, this kind of study helps reduce the required experimental measurements for the improvement and design of hydraulic machines.
Physics-assisted recursive method for sample selection from wall-bounded turbulence data
Authors: Zhu Linyang , Wang Tian , Fan Zhaolin , Xiang Xinghao , Zhang Weiwei , Yuan Xianxu
Published: July 2022

The purpose of this work is to improve the efficiency of sample selection with the recursive method for wall-bounded turbulent flows. In the proposed physics-assisted recursive method, the flow field is divided into several sub-regions along the wall distance. Since the distributions of the flow variables have certain similarity along the wall normal direction, fast clustering of similar data can be achieved, which paves the way for the rapid elimination of redundant data. Then, the recursive method is used for sample selection in each sub-region. The effectiveness of the proposed method is investigated through several cases. The results show that the proposed method has good convergence and grid independence and improves the computational efficiency of the recursive method for sample selection. Since the amount of training data is reduced, the time consumption of model training is decreased. In addition, it is demonstrated that sample selection can also be helpful to achieve more balanced model performance by changing the distribution of training data.
Mixing performance of the induced charge electro-osmosis micromixer with conductive chamber edges for viscoelastic fluid
Authors: Chen Yi , Lv Zhuoyao , Wei Yuqi , Li Jie
Published: July 2022

Enhancing the micro-channel flow mixing is always a difficult problem. In this study, a micromixer based on induced charge electro-osmosis is proposed. A T-shaped micromixer, which has a chamber with conductive surfaces in the channel, is chosen. Due to the electro-osmotic effect of the induced charge, the induced potential is generated on the conductive surface. The Oldroyd-B constitutive model is chosen to characterize the flow characteristics of polyacrylamide solution, and an open-source solver named rheoTool based on the finite-volume method is used. The effect of the chamber shape, the chamber size, the conductive edge numbers in the chamber, and the applied electric intensity on the mixing efficiency are investigated. The results show that the micromixer with conductive edges in the chamber has better mixing effect because of the vortices. At the same time, compared with other shapes, the micromixer with diamond chamber has the best mixing effect, and the mixing efficiency reaches 79.51%. In addition, the mixing efficiency of one conductive edge in the diamond chamber is 4.39% higher than that of the two conductive edges chamber. It is found that increasing the chamber size will improve the mixing efficiency, and the mixing efficiency increased by 12.76% with the increase in chamber size. On the other hand, when increasing the electric field intensity from 100 to 200 V/cm, the mixing efficiency will decrease.
Direct numerical simulation of turbulence anisotropy and growth rate in the supersonic non-isothermal mixing layer
Authors: Dai Qi , Wang Xiang , Feng Wenbin , Zhao Zijie , Guo Zeqing , Chen Zhihua
Published: July 2022

By direct numerical simulations, non-isothermal effects on turbulence anisotropy and growth rate are investigated in three-dimensional spatially developing supersonic mixing layers with high convective Mach numbers (Mc > 0.6). Hot air is blown into the high-speed stream, and cold air is added on the low-speed side. Two non-isothermal simulations with different temperature gradients are conducted and compared with the isothermal mixing layer. The Reynolds stress transport is analyzed to reveal the underlying modulation mechanisms by temperature gradients. The supersonic mixing layer is significantly anisotropic, and the streamwise turbulent intensity is larger than the transverse and spanwise turbulent intensities. The non-isothermal effects enhance the energy transfer from the streamwise Reynolds stress to transverse and spanwise Reynolds stresses in the initial shear layer, and the mixing layer anisotropy is intensely attenuated, which is attributed to the increment of the flow instability. Thus, the shear layer growth is initially accelerated, and the supersonic mixing layer is destabilized. However, the fluid viscosity and the viscous dissipation are enhanced, and the Reynolds stresses decay more strongly in the fully developed region. The transverse and spanwise turbulent intensities decrease more than the streamwise turbulent intensity due to the attenuation of the correlation between pressure and dilatation fluctuations. Consequently, the shear layer turbulence anisotropy is augmented with stronger three-dimensionality. As the Reynolds shear stress is reduced and the entrainment of irrotational fluid from the free streams into the shear layer is attenuated, the mixing layer growth rate is decreased in the self-similar turbulence.
Effect of blade curve shape on the hydraulic performance and pressure pulsation of a pump as turbine
Authors: Xiang Ru , Wang Tao , Fang Yujian , Yu He , Zhou Min , Zhang Xiang
Published: July 2022

As an economical and convenient device, a pump as turbine (PAT) is widely preferred in the energy recovery process and micro-hydropower plants. To study the operational stability of a PAT, a forward-curved impeller and a back-curved impeller were designed in this paper. A verified computational fluid dynamics technique is used to compare the two different impellers in terms of the external characteristics, energy loss, and pressure pulsation under the partial load flow rate (0.8Qr), design condition (1.0Qr), and overload flow rate (1.2Qr). The results show that the total entropy generation power of the forward-curved impeller is 41.6%, 49.2%, and 53.6%, respectively, which are lower than that of the back-curved impeller. At the best efficiency point, the head, shaft power, and efficiency of the forward-curved impeller are 9.8%, 18.4%, and 13.1%, respectively, which is obviously better than that of the back-curved impeller. Similarly, the main frequency of the pressure pulsation in volute is the blade-passing frequency, and that of the impeller is the shaft frequency. Compared with the back-curved PAT, the pressure pulsations of the forward-curved PAT are decreased by 92.24%, 73.18%, and 62.22% in volute, impeller, and draft tube, respectively. This paper reveals that the forward-curved impeller not only obviously improves hydraulic performance but also significantly improves pressure pulsations within a PAT.
Effect of asphaltene on the rheological properties of bitumen
Authors: Xiong Ruiying , Piette Jourdain H. , Zhang Ziyue , Guo Jixiang , Hatzikiriakos Savvas G.
Published: July 2022

In this paper, the rheological behavior of bitumen as a function of asphaltene concentration has been studied. Several bitumen samples having distinctly different amounts of asphaltene were prepared and characterized using differential scanning calorimetry and rheological measurements. The glass transition temperature of bitumen increases with an increase of the asphaltene concentration. This correlation can be used to estimate the asphaltene concentration of bitumen samples using DSC measurements. Small-amplitude oscillatory shear data for the bitumen-derived samples were fit by the generalized Maxwell model with good agreement. A constitutive model is proposed, where the zero-shear complex viscosity of the bitumen sample is a strong function of the asphaltene concentration, and it can be used to predict the asphaltene concentration.
Artificial Intelligence Systems
Authors: Ali Saud Al Tobi Maamar , Bevan Geraint
Published: July 2022

The previous chapter presented some of the conventional methods that can be used in machinery condition monitoring. Moreover, it is significant to explore some of the advanced methods such as the Artificial Intelligence (AI) schemes. AI is employed in the condition monitoring and diagnosis of fault conditions in centrifugal pumps and rotating machines. It uses automatic diagnostic system known as classifiers in addition to pre-processing scheme like Wavelet Transform (WT) to provide solutions are required to improve its application in fault diagnosis of centrifugal pumps and rotating machines as presented in this chapter.
General Rigid Bead-Rod Macromolecular Theory
Authors: Kanso Mona , Giacomin Alan Jeffrey
Published: July 2022

In the general rigid bead-rod theory, we explain the elasticity of a polymeric liquid by considering just the orientation of a suspension of macromolecules. With the general rigid bead-rod theory, we construct macromolecules from sets of beads whose positions, relative to one another, are fixed. The general rigid bead-rod theory is, thus, not to be confused with a freely jointed chain, where the beads are rigidly separated but the joints rotate freely. Our macromolecular bead-rod models are suspended in a Newtonian solvent. In this work, we neglect interactions of the solvent velocity fields, be they between the nearest beads (Stewart and Sørensen, 1972; and Piette et al., 2019b)1 or the nearestmacromolecules. With the general rigid bead-rod theory, we, thus, locate beads and their dimensionless massless rods along molecular chains, including rings, backbones, or branches. In this way, we can model anymacromolecular architecture. To any such collection of masses, we can associate a moment of inertia ellipsoid (MIE) whose center is the center of mass and whose principal moments of inertia match those of the macromolecule. The MIE determines the orientability of the macromolecules and, thus, the polymer contribution to the rheological properties.
Rheology of Mucins
Authors: Fischer Peter
Published: July 2022

Mucus is a highly glycosylated protein protecting the epidermal cells and can be found in respiratory, gastrointestinal, urogenital, and vaginal tracts of animals and humans. In fish and aquatic invertebrates, mucus can also be found on the ‘outside’ as an antimicrobial barrier and physically protective layer of skin and gills. Mucus is not only the first line of defense but also provides a filtering function for nutrients and gases to pass to the epidermal cell. In this dual role as gateway, mucus is exposed to numerous kinds of external stimuli and varies depending on the organ in chemical composition and thus exhibits different physio-chemical and mechanical properties. For example, mucus-stimuli interaction is studied for food uptake in the gastrointestinal tract, interaction with bacteria and viruses, nanoparticle interaction in the respiratory tract, and filter feeding in marine invertebrates. In this book chapter, the rheological properties of mucus per se and under different environmental exposure will be reviewed and put into perspective to its specific biological tasks. Further, inherent problems related to mucus origin and harvesting as well as appropriate rheological testing methods will be discussed.
Blood Rheology and Biomedical Implications
Authors: Fedosov Dmitry A. , Gompper Gerhard
Published: July 2022

Blood rheology plays an essential role in the functioning of complex organisms, as blood flow facilitates the transport of oxygen and nutrients, the immune response, and the self-healing of the vessel network after injury. Furthermore, changes in blood rheology can often be used as a biomarker for blood-related diseases and disorders. One of the prominent questions is how macroscopic properties of blood emerge from the mechanical properties of suspended cells, their flow dynamics, and interactions between them. Blood rheology, which is mainly determined by the red blood cells, also strongly affects the behavior of other blood components, such as white blood cells, platelets, and von Willebrand factor. In this chapter, we review recent advances in blood rheology by covering the behavior of single cells and multicellular suspensions in shear and microvessel flows. In particular, we discuss physical mechanisms of blood shear thinning which arises from a rich behavior of red blood cells in shear flow. Furthermore, the distribution of various suspended components in blood flow is described. Finally, several biomedical implications of blood rheological properties are discussed in the context of malaria and sickle-cell disease.
Contact Force Effects on Rheology of Dense Suspensions
Authors: Morris Jeffrey F.
Published: July 2022

The extreme rate dependence of dense suspensions has been related to the influence of contact forces, with tribological effects such as frictional interactions and other constraints on motion now generally accepted as playing some role. Theory and simulation have shown how contact with a frictional interaction, caused by overcoming a repulsive interparticle force, can lead to discontinuous shear thickening or shear jamming at large stress. Experimental study has shown that elements of this description are appropriate, but it is generally oversimplified. The influence of contact forces at small stress is found in the yielding behavior, and this is also considered here, for cases where an attractive interparticle force is involved. Measurement of particle frictional interactions is also discussed.
Stress accumulation by confined ice in a temperature gradient
Authors: Gerber Dominic , Wilen Lawrence A. , Poydenot Florian , Dufresne Eric R. , Style Robert W.
Published: July 2022

When materials freeze, they often undergo damage due to ice growth. Although this damage is commonly ascribed to the volumetric expansion of water upon freezing, it is usually driven by the flow of water toward growing ice crystals that feeds their growth. The freezing of this additional water can cause a large buildup of stress. Here, we demonstrate a technique for characterizing this stress buildup with unprecedented spatial resolution. We create a stable ice–water interface in a controlled temperature gradient and measure the deformation of the confining boundary. Analysis of the deformation field reveals stresses applied to the boundary with

O

(micrometers) spatial resolution. Globally, stresses increase steadily over time as liquid water is transported to more deeply undercooled regions. Locally, stresses increase until ice growth is stalled by the confining stresses. Importantly, we find a strong localization of stresses, which significantly increases the likelihood of damage caused by the presence of ice, even in apparently benign freezing situations. Ultimately, the limiting stress that the ice exerts is proportional to the local undercooling, in accordance with the Clapeyron equation, which describes the equilibrium between a stressed solid and its melt. Our results are closely connected to the condensation pressure during liquid–liquid phase separation and the crystallization pressure for growing crystals. Thus, they are highly relevant in fields ranging from cryopreservation and frost heave to food science, rock weathering, and art conservation.
Vibrational couplings between protein and cofactor in bacterial phytochrome Agp1 revealed by 2D-IR spectroscopy
Authors: Buhrke David , Michael Norbert , Hamm Peter
Published: July 2022

Phytochromes are ubiquitous photoreceptor proteins that undergo a significant refolding of secondary structure in response to initial photoisomerization of the chromophoric group. This process is important for the signal transduction through the protein and thus its regulatory function in different organisms. Here, we employ two-dimensional infrared absorption (2D-IR) spectroscopy, an ultrafast spectroscopic technique that is sensitive to vibrational couplings, to study the photoreaction of bacterial phytochrome Agp1. By calculating difference spectra with respect to the photoactivation, we are able to isolate sharp difference cross-peaks that report on local changes in vibrational couplings between different sites of the chromophore and the protein. These results indicate inter alia that a dipole coupling between the chromophore and the so-called tongue region plays a role in stabilizing the protein in the light-activated state.
Dynamic compression behaviour and constitutive description of fine-grain Mg–4Zn–1Y alloy
Authors: Liu Xuanyu , Mao Pingli , Wu Xiaoxu , Liu Zheng , Zhou Le , Wang Zhi , Wang Feng
Published: July 2022

In this research, the dynamic compression behaviour of 5 and 1.5 µm grain size samples of Mg–4Zn–1Y alloy was investigated by the split Hopkinson pressure bar at the strain rate of 1000–1700 s−1. The microstructure, texture evolution, and the deformation mechanisms of samples were characterised by electron backscattering diffraction. The result showed that the grain refinement caused tension twining, which resulted in the distinct true stress–strain curves with specific grain sizes. It was found that the pyramidal < c + a > and pyramidal  slips were the main deformation mechanisms of 5 and 1.5 µm samples under dynamic compression, respectively. The constitutive modelling of Mg–4Zn–1Y with different grain sizes was also developed by introducing the grain size adjustment parameters.
Trailing rotating-extrusion-assisted wire arc additive manufacturing of duplex stainless steel
Authors: Yu Chen , Zhao Yunqiang , Xu Wanghui , Dong Chunlin , Guo Chunfu , Deng Jun , Li Zhenlong , Miao Shu
Published: July 2022

A trailing rotating-extrusion-assisted wire arc additive manufacturing method was proposed and investigated. Conventional method can fabricate large components with complex structures. Here, we demonstrate that the performance of components can be improved. The deposited layer was deformed under trailing rotating-extrusion treatment. The surface morphology of the deposited layers changed from scaly bulges to a flat surface with flashes on both sides. Materials after the rotating-extrusion treatment had obvious grain refinement regions, in which the original coarse columnar crystals were refined. The proportion of austenite increased significantly. The average hardness of the rotating-extrusion region was 317.7 HV0.5 which was 19% higher than that of the original region. The tensile strength of the sample fabricated by the new method was improved.
Single-mode and ultra-broadband gigahertz surface acoustic waveguides on AlN-on-SiC substrates
Authors: Wang Yong , Wu Shu-Mao , Yu Si-Yuan , Wu Yongzhong , Hao Xiaopeng , Chen Yan-Feng
Published: July 2022

This paper proposes a class of high-performance surface acoustic wave (SAW) waveguides based on AlN-on-SiC substrates. Under the existing crystal growth and processing technology, these SAW waveguides offer excellent performance in single mode, low loss, ultra-broadband, operating at gigahertz frequencies. Quasi-Rayleigh SAWs can be excited by traditional interdigital transducers and guided freely with excellent efficiency. Based on these SAW waveguides, we further demonstrate SAW splitters and ring cavities with ultra-high qualities up to 107. These SAW components complement future integrated phononic circuits for high-frequency and compact acoustic manipulating, signal processing, sensing, computing, etc.
Theoretical and experimental studies on bistable vibration energy harvester with levitation magnet couple
Authors: Deng Wangzheng , Qin Weiyang , Zhang Pengtian
Published: July 2022

To improve the efficiency of vibration energy harvesting, a levitation magnet couple is introduced to the bi-stable energy harvester (BEH) to create a desired potential energy, by which the harvester’s response and output can be increased greatly. Compared to the classical BEH, the novel harvester has a lower potential barrier and a flatter bottom of its potential well, which can help increase the response and outputs. The experimental results show that the introduction of levitation magnet couple effectively extends the working frequency bandwidth of the harvester. The inter-well jump can be executed easily under weak stochastic excitations and the amplitude is larger than the classical one, even in the case of executing the same kind of intra-well oscillation. The experiments prove that the output voltage of the novel harvester outperforms the classical BEH over the whole intensity range. This study may provide a good guidance to improving the performance of bistable energy harvester.
Symmetry breaking radiative corrections to B to tensor meson form factors at large recoil
Authors: Sikandar Arslan , Aslam M Jamil , Ahmed Ishtiaq , Shafaq Saba
Published: July 2022

In heavy-to-light B decays, the heavy-quark/large-energy symmetry reduces the number of QCD form factors. At large final state meson energy, these form factors receive sizeable perturbative corrections. The hard-gluon vertex corrections are absorbed in the coefficients of soft-form factors, while the hard-spectator interactions generate symmetry-breaking corrections and end-point singularities. At an order of 1/m
b, using the heavy-quark/large-energy symmetry, the end-point singularities can also be absorbed in the soft form factors, whereas the symmetry breaking corrections add separately to the form factors. In this work, we calculate these perturbative corrections for B → Tμ
+
μ
− decays, with T representing the tensor mesons

K

2

*

,

f

2

,

a

2

all having J

P
= 2+. We find that the values of the branching ratio (Br) and the zero-position of the forward–backward asymmetry

(

A

F
B

)

of

B
→

K

2

*

μ

+

μ

−

decay receive nearly 5% and 14% contributions, respectively, from these radiative corrections. Compared to these observables, the radiative corrections change the averaged longitudinal lepton polarization asymmetry (⟨P
L⟩) by 13%. Therefore, prior to attributing any deviation from the SM predictions of these asymmetries as a hint of NP, one has to take into account the contributions of vertex and hard-spectator corrections.
A multiscale local pattern filtering method for noise mode identification of dynamic signals in bridges
Authors: Wang Boxin , Wang Zihao , He Dawei , Yang Haitao , Gao Xin
Published: July 2022

The problem of effective information extraction of dynamic signals is a key challenge of vibration-based structural health monitoring. Traditional ensemble empirical mode decomposition (EEMD) and complementary EEMD (CEEMD) are effective filtering methods but have the shortcomings of mode mixing, completeness and the endpoint effect in adaptive decomposition stage. To address the above problems, this paper proposes a noise mode identification method based on multiscale local pattern filtering with a machine learning algorithm. In addition, this method improves the filtering performance of mode decomposition and wavelet threshold denoising methods effectively. To validate the performance of this method, simulation experiment and real signal analysis were used for validation: their results showed that the proposed method has better adaptive decomposition performance than EEMD and CEEMD. Compared with the EEMD, CEEMD and wavelet threshold denoising methods, the proposed method can better balance smoothness and the power reserve, has optimized time- and frequency-domain characteristics, filters with a higher signal-to-noise ratio and reliability, and has more optimized filtering performance. The method proposed in this paper can be applied to bridge health monitoring technology, and has important scientific and engineering significance.
Stress-driven structural and bond reconstruction in 2D ferromagnetic semiconductor VSe2
Authors: Yu Bo-Wen , Liu Bang-Gui
Published: July 2022

Two-dimensional (2D) semiconducting transition metal dichalcogenides can be used to make high-performance electronic, spintronic, and optoelectronic devices. Recently, room-temperature ferromagnetism and semiconduction in 2D VSe2 nanoflakes were attributed to the stable 2H-phase of VSe2 in the 2D limit. Here, our first-principles investigation shows that a metastable semiconducting H′ phase can be formed from the H VSe2 monolayer through uniaxial stress or uniaxial strain. The calculated phonon spectra indicate the dynamical stability of the metastable H′ VSe2 and the path of phase switching between the H and H′ VSe2 phases is calculated. For the uniaxial stress (or strain) scheme, the H′ phase can become lower in total energy than the H phase at a transition point. The H′ phase has stronger ferromagnetism and its Curier temperature can be enhanced by applying uniaxial stress or strain. Applying uniaxial stress or strain can substantially change spin-resolved electronic structures, energy band edges, and effective carrier masses for both of the H and H′ phases, and can cause some flat bands near the band edges in the strained H′ phase. Further analysis indicates that one of the Se–Se bonds in the H′ phase can be shortened by 19% and the related Se–V–Se bond angles are reduced by 23% with respect to those of the H phase, which is believed to increase the Se–Se covalence feature and reduce the valence of the nearby V atoms. Therefore, structural and bond reconstruction can be realized by applying uniaxial stress in such 2D ferromagnetic semiconductors for potential spintronic and optoelectronic applications.