bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical study of periodic flame flashback in a cavity-based scramjet combustor
Authors: Guo Shengzu , Zhang Xu , Liu Qili , Yue Lianjie
Published: March 2023

The periodic flame flashback phenomenon in an ethylene-fueled cavity-based scramjet combustor was numerically investigated by a three-dimensional unsteady Reynolds-averaged Navier–Stokes solver with two-step kinetics. The air inflow stagnation temperature is 1225 K, and its Mach number is 2.6. Spectral analyses revealed the combustion oscillations with flame flashbacks maintained in the separated scramjet mode with the establishment/vanishment of flow separation near the fuel injector, differing from previous studies of flame flashbacks connected to the ramjet/scramjet mode transitions. A mechanism with four evolution stages was proposed to elucidate the flow-flame interaction. In stage I, a rapid flame flashback upstream and shock-train extension were caused by the high-temperature induced auto-ignition tendency of well-mixed unburned gas in the near-sidewall low-speed region. In stage II, the combustion-induced back pressure and shock train gradually achieved an aerodynamic balance. The combustion flow barely changed in stage III. Meanwhile, a simplified model suggested that the gradual temperature rises occurring upstream of the cavity and away from the sidewall were caused by spanwise heat conduction. The higher temperatures would cause upstream flame propagation with enhanced heat release due to auto-ignition. However, the enhanced heat release occurred mostly in the subsonic flow, resulting in pressure decreases according to one-dimensional flow equations. A smaller near-sidewall separation was produced by the lower back-pressures, which prompted the rapid flame recession downstream in stage IV. Moreover, a simplified flame-spreading model was proposed to illuminate the flame propagation nature. The comparison of flame speeds with theoretical estimations indicated that the current flame was in the regime of turbulent flame propagation, rather than the C–J detonation or deflagration speculated in previous studies.
Modeling the evaporation of sessile drops deformed by gravity on hydrophilic and hydrophobic substrates
Authors: Tonini S. , Cossali G. E.
Published: March 2023

Evaporation of sessile drops deformed by gravity is quantified by an analytical–numerical approach. The shape of the drops is defined by minimizing the interfacial and potential drop energies, following a variational integral approach, for a wide range of drop sizes (from 2.7 μl to 1.4 ml for water drops) and contact angles for both hydrophilic and hydrophobic substrates. The extension of an analytical model for drop evaporation, which accounts for the effect of the Stefan flow and the temperature dependence of thermophysical properties, to the present conditions reduces the problem to the solution of a Laplace equation, which is then numerically calculated using COMSOL Multiphysics®. The vapor fluxes and evaporation rates are then quantified, and the systematic approach to the problem allows the derivation of two correlations, for hydrophilic and hydrophobic substrates, respectively, that can be used to correct the evaporation rate calculated for a drop of the same volume and contact angle in the absence of gravity effects.
Novel tungsten nitride crystal providing nanochannels for hydrogen removal and recycling in PFMs
Authors: Yu Pengfei , Pan Bicai
Published: March 2023

Hydrogen (H) removal in plasma-facing materials (PFMs) has been an important issue in the field of manually controllable fusion reactions. The tungsten nitride (WNx) film, as a by-product on the divertor surface in the fusion reactor after nitrogen seeding, has rich H retention, and much attention should be given to hydrogen removal from WNx. In this paper, by using density functional theory calculations, we predicted a novel W24N48 crystal, which possesses nanoscale cavities and channels inside, and studied the interaction between it and hydrogen. We found that the N atoms inside the crystal are favorable for the adsorption of atomic hydrogen. When more hydrogen atoms are injected, the hydrogen atoms adsorbed in the crystal react with the newly entered hydrogen atoms to form hydrogen molecules. These newly formed H2 molecules can easily move through the nanochannels in W24N48 and serve to remove hydrogen. Our calculations suggest that when this new W24N48 material is embedded in the WNx film on the surface of the PFMs, the nanochannels will be helpful in removing and recycling hydrogen isotopes in the PFMs.
The association of pet ownership and sleep quality and sleep disorders in United States adults
Authors: Medlin Kayla , Wisnieski Lauren
Published: March 2023

Prior studies on the association between pet ownership and sleep quality and sleep disorders have varied results. Pet ownership may be beneficial for an owner’s quality of sleep due to the social support that pets provide. Pets offer a sense of security and companionship, which may result in improvements in levels of anxiety, stress, and depression. Alternatively, pets may disrupt their owners’ sleep. Therefore, this cross-sectional study aimed to determine if there is an association between dog and cat ownership and sleep quality and sleep disorders using data from the National Health and Nutrition Examination Survey (NHANES) conducted in 2005–2006. Separate multivariable logistic regression models were built to assess the association between pet ownership and sleep quality outcomes, which included the following: snoring, snorting, sleep disorder diagnoses, trouble sleeping, trouble falling asleep, waking up during the night, waking up too early, feeling unrested, feeling sleepy, not getting enough sleep, needing pills to sleep, leg jerks and cramps, taking longer than 15 minutes to fall asleep, and getting less than 6 hours of sleep on average. Demographics and body mass index (BMI) were adjusted in a series of hierarchical logistic regression analyses. Our results indicated that having a dog was associated with greater odds of having a sleep disorder and having trouble sleeping. Having a cat was associated with greater odds of having leg jerks. While the causal nature of pet ownership on sleep quality and sleep disorders was unable to be established, the results of this study are consistent with previous studies that found that pet ownership has a negative impact on sleep quality. The results of this study can inform randomized controlled trials for patients with poor sleep quality.
Rubber toughened glass fibre reinforced high impact polystyrene
Authors: Alsewailem Fares D. , Al-ameri Abdulrahman M.
Published: March 2023

This study aimed to investigate the effect of combining reinforcement agents (i.e. glass fibres) and rubber particles (ethylene-propylene grafted maleic anhydride, EP-g-MA) on the properties of high impact polystyrene (HIPS). HIPS was melt blended and compounded with EP-g-MA and glass fibres at a total weight percentage of both constituents ranging from 0 to 10 wt-%. HIPS content was kept fixed in all prepared samples of 90 wt-%. Samples for testing were prepared in accordance with ASTM 265D and ASTM D 1708 for Izod impact strength and tensile strength, respectively. It was shown that the toughness of HIPS could be significantly enhanced by proper combination of EP-g-MA and glass fibres. Composites with EP-g-MA content greater than 7 wt-% and glass fibre content of 3 wt-% had izod impact strength values greater than 99 J m−1 which reflects 11–77% enhancement over those value for neat HIPS and HIPS reinforced with 10 wt-% glass fibres .
Open Thy Lattice Osteoclast, Resorb me!
Authors: Bakiri Latifa
Published: March 2023

Osteoclasts degrade bone using Cathepsin K and two metalloproteinases: MMP9 and MMP14. In addition to cleaving collagen, Zhu et al. (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202206121) discover that MMP9 and MMP14 also proteolyze galectin-3 on the cell surface. This process drives a galectin-3/LRP1 signaling axis that supports the hard tissue-resorbing function of osteoclasts.
A 700 W⋅h⋅kg−1 Rechargeable Pouch Type Lithium Battery
Authors: Li Quan , Yang Yang , Yu Xiqian , Li Hong
Published: March 2023

High-energy-density rechargeable lithium batteries are being pursued by researchers because of their revolutionary potential nature. Current advanced practical lithium-ion batteries have an energy density of around 300 W⋅h⋅kg−1. Continuing to increase the energy density of batteries to a higher level could lead to a major explosion development in some fields, such as electric aviation. Here, we have manufactured practical pouch-type rechargeable lithium batteries with both a gravimetric energy density of 711.3 W⋅h⋅kg−1 and a volumetric energy density of 1653.65 W⋅h⋅L−1. This is achieved through the use of high-performance battery materials including high-capacity lithium-rich manganese-based cathode and thin lithium metal anode with high specific energy, combined with extremely advanced process technologies such as high-loading electrode preparation and lean electrolyte injection. In this battery material system, the structural stability of cathode material in a widened charge/discharge voltage range and the deposition/dissolution behavior of interfacial modified thin lithium electrode are studied.
Path integral suppression of badly behaved causal sets
Authors: Carlip P , Carlip S , Surya S
Published: March 2023

Causal set theory is a discrete model of spacetime that retains a notion of causal structure. We understand how to construct causal sets that approximate a given spacetime, but most causal sets are not at all manifold-like, and must be dynamically excluded if something like our Universe is to emerge from the theory. Here we show that the most common of these ‘bad’ causal sets, the Kleitman–Rothschild orders, are strongly suppressed in the gravitational path integral, and we provide evidence that a large class of other ‘bad’ causal sets are similarly suppressed. It thus becomes plausible that continuum behavior could emerge naturally from causal set quantum theory.
Attosecond ionization dynamics of modulated, few-cycle XUV pulses
Authors: Ziems Karl Michael , Wollenhaupt Matthias , Gräfe Stefanie , Schubert Alexander
Published: March 2023

Few-cycle, attosecond extreme ultraviolet (XUV) pulses in the strong field regime are becoming experimentally feasible, prompting theoretical investigating of the ionization dynamics induced by such pulses. Here, we provide a systematic study of the atomic ionization dynamics beyond the regime of the slowly varying envelope approximation. We discuss the properties of such XUV pulses and report on temporal and spectral modulations unique to the attosecond nature of the pulse. By employing different levels of theory, namely the numerical solution to the time-dependent Schrödinger equation, perturbation theory and a semi-analytical approach, we investigate the ionization of atoms by modulated, few-cycle XUV pulses and distinguish first and higher order effects. In particular, we study attosecond ionization in different intensity regimes aided by a general wave function splitting algorithm. Our results show that polarization and interference effects in the continuum prominently drive ionization in the few-cycle regime and report on carrier-envelope phase (CEP)- and intensity-dependent asymmetries in the photoelectron spectra. The use of spectrally modulated attosecond pulses allows us to distinguish between temporal effects causing asymmetries and dynamic interference, and spectral effects inducing a redshift of the photoelectron spectrum.
Bi-chromatic driver enabled control of high harmonic generation in atomic targets
Authors: Rajpoot Rambabu , Holkundkar Amol R
Published: March 2023

We investigated the high-order harmonic generation from interacting time-delayed, linearly polarized bi-chromatic laser pulses with the atomic target. The frequency ratio of secondary to primary fields (

ω
2

/

ω
1

), along with the carrier-envelope-phase (CEP) and respective time-delay between the two pulses, are very instrumental in controlling the ionization of the electron and so the quantum dynamics in the continuum. We observed an optimum CEP (φ) and time delay (

t

d

) for a given bi-chromatic frequency ratio, giving maximum cutoff energy. We studied the effect of CEP and time delay for a fixed frequency ratio and observed that the harmonic cutoff could be controlled in an experimentally feasible way. Moreover, the harmonic yield in the energy range 140 eV–240 eV was also calculated, and it was observed that the harmonic yield scales as

∝
−

ϕ

5

/

6

. The attosecond pulses for different CEP were also calculated by superposing the harmonics in the same energy range, and

∼

200

pulses were observed with peak intensity decreasing with CEP, following the variation of respective harmonic yield with CEP.
Modelling of coupled magnetoelastic waves in structure containing thin antiferromagnetic films on an elastic substrate
Authors: Bogdanova T V , Kalyabin D V , Safin A R , Nikitov S A
Published: March 2023

In this work we present a model explaining the properties of magnetoelastic waves propagation in the heterostructure containing an antiferromagnetic layer on a non-magnetic elastic substate. Horizontally polarized shear surface waves (SH-waves) propagating in thin film are Love waves. The dispersion characteristic of magnetoelastic waves in such structure was obtained, and the effect of variation of the thickness of the antiferromagnetic layer and the external magnetic field on the frequency of the magnetoelastic resonance was also studied. It was found that an increase in the magnetic field magnitude leads to the increase in the magnetoelastic resonance frequency, and, on the contrary, with an increase in the thickness of the AFM layer the magnitude of the magnetoelastic resonance frequency decreases. The obtained results can be used to develop devices for generating and processing signals in the GHz and THz frequency ranges.
Dynamics and feedback sensitivity of vertical-cavity surface-emitting lasers with arbitrary optical feedback intensity
Authors: Hao Chenxi , Zheng Wanhua , Liu Anjin
Published: March 2023

Vertical cavity surface emitting lasers (VCSELs) are the key laser sources in the high-performance computers (HPCs) and data centers (DCs). The explosive growth of data traffic in the HPCs and DCs requires increased bandwidths of VCSELs. In this paper, we deduce the Time-Delay (T-D) model considering the multiple round trips of light in VCSELs with an optical feedback cavity to enhance the modulation bandwidth. The T-D model is suitable for the VCSEL with an arbitrary optical feedback intensity. The influences of the round trip time m of light in the optical feedback cavity on the intensity-modulation responses with strong and weak optical feedback are studied. The feedback coefficients considering the multiple round trips of light in the optical feedback cavity and the dispersions of the distributed Bragg reflector are deduced, and are suitable for the arbitrary optical feedback intensity. The feedback coefficients are influenced by the value of m and the optical feedback intensity, and decrease as the value of m under arbitrary optical feedback intensity increases. The feedback coefficients under strong optical feedback are larger than that under weak optical feedback with the same value of m. The theories are useful for the high-speed VCSELs with optical feedback.
New insights into the photocatalytic and magnetic activity of Co-doped BiFeO3 nanoparticles via competing structures
Authors: Nie Yao , Ma Haoen , Wang Zheng , Lan Changyong , Zhang Wei , Chen Leiming , Huang Chuanfu
Published: March 2023

Cobalt was chosen as the doping element for BiFeO3 (BFO), and pure BFO and a series of BiFe1−x
Co
x
O3 (x = 0.03, 0.05, 0.07, 0.09) nanoparticles, correspondingly labeled as nBFCO (n = 3, 5, 7, 9), were successfully prepared and investigated based on the sol-gel method in this paper. The synthesized nanoparticles were characterized by x-ray diffraction, field emission scanning electron microscopy, Brunauer−Emmett−Teller surface area, x-ray photoelectron spectroscopy and ultraviolet-visible light absorption. With the increase in the doping level of cobalt in BFO, a competing structure wandering between rhombohedral and orthorhombic structures was observed in the experiment. For instance, the microstructure characterization clearly indicates coexistence of the rhombohedral and orthorhombic structures in 7BFCO. Meanwhile, the bandgap of BFO was significantly reduced from 2.04 eV to 1.78 eV. The photocatalytic degradation of Rhodamine B of samples in an aqueous solution was investigated under different wavelengths of light. We found that 7BFCO was the optimal proportion for acquiring the photocatalytic and magnetic activity in this work, e.g. the photocatalytic efficiency can reach 98.2%. The underlying physics based on the lattice structure, size effects and energy gap is also discussed.
Electron-phonon coupling in La3In under pressure
Authors: Singh Surinder , Pinsook Udomsilp
Published: March 2023

Conventional superconducting parameters Eliashberg spectral function, phonon DOS, average electron-phonon coupling constant & superconducting transition temperature of La3In were calculated at ambient and applied positive hydrostatic pressure. Ambient pressure electron-phonon coupling constant was found to be 1.43 and superconducting transition temperature was calculated to be 8.7 K which is close to the experimental reported value of 9.5 K. Logarithmic average phonon frequency at ambient pressure was found to be 6.21 × 10−3 eV. Phonon dispersion relations for the ambient and applied positive hydrostatic pressure were calculated to confirm the dynamical stability of La3In under positive pressure. Acoustic modes of vibrations were found to mediate most of the electron-phonon-electron interaction with a very small contribution from optical modes of vibrations. Fermi surface at ambient pressure was also calculated and employed in explaining the large value of the calculated electron-phonon coupling constant. The effect of spin–orbit coupling on electronic, phonon and superconducting properties of La3In was also studied.
Close contact restriction periods for patients who have received iodine-131 therapy for differentiated thyroid cancer
Authors: Forster Jake C , Badger Daniel , Hickson Kevin J
Published: March 2023

Patients treated with radionuclide therapy usually require restrictions on certain activities for a period of time following treatment to optimise protection of the public and ensure the legal dose limit is not exceeded. Software may be used to calculate necessary restriction periods for an individual based on longitudinal dose rate measurements from the time of radiopharmaceutical administration. A spreadsheet program has been used for this purpose in Australian hospitals for the last two decades. However, this spreadsheet has a limitation in that it uses an approximation in the calculation of dose from a contact pattern, which affects the calculated restriction period. A computer program called Dorn was developed that provides the same functionality as the spreadsheet but without this approximation. Proffered radiation safety advice from Dorn and the spreadsheet were compared. Advice from the spreadsheet and Dorn were compared for 55 patients who underwent iodine-131 therapy for differentiated thyroid cancer. The restriction periods for caring for infants, close contact with children and sleeping with a partner were typically about 13 h longer in Dorn than in the spreadsheet, but in some cases were over a week shorter or a month longer. If the Dorn program is used clinically in place of the spreadsheet, some patients will enjoy shorter restriction periods and the therapy provider can be more confident in their compliance with regulatory requirements and best practice. Dorn is freely available from https://doi.org/jg5f.
Contact restriction time after common nuclear medicine therapies: spreadsheet implementation based on conservative retention function and individual measurements
Authors: Broggio D , Célier D , Michel C , Isambert A
Published: March 2023

The increasing use of new radiopharmaceuticals invites us to reconsider some radiation protection issues, such as the contact restriction time that limits public exposure by nuclear medicine patients. Contact restriction time should be patient specific and conservative, and its assessment made easy for clinicians. Here a method is proposed based on conservative estimation of the whole-body retention function and at least one measurement of the patient’s dose rate. Recommended values of the retention function are given for eight therapies: 131I (Graves’ disease, remnant ablation, patient follow-up, meta-iodobenzylguanidine), 177Lu-prostate-specific membrane antigen and 177Lu-DOTATATE therapies, and 90Y and 166Ho microsphere injection of the liver. The patient line source model for scaling dose rate from one distance to another is included in the restriction time calculation. The method is benchmarked against published values and the influence of the dose rate scaling and whole-body retention function illustrated. A spreadsheet is provided, along with the source code, with recommended values for the eight therapies. The recommended values can be changed as well as the dose rate scaling function, and other radiopharmaceuticals can be included in the spreadsheet provided retention functions are defined.
Effects of Reynolds number and solidity ratio on advection dominated mixing in a high-altitude instrument
Authors: Pamarty Abhijit Pranav , Mascarenhas Craig , Anderson James G
Published: March 2023

Due to the role of ClO and BrO in the rate-limiting step of the catalytic cycles enabling ozone loss, measurement of concentrations of these halogen molecules is of critical importance to understanding the loss rate of ozone in the stratosphere. A key advantage of in situ measurements is that these rate-limiting molecules can be observed simultaneously with ozone in the same volume element of the stratosphere, with high spatial and temporal resolution. Historically, these in situ measurements were made using instruments on the NASA ER-2 flight platform for a few hours at a time. However, the development and advancement of a high-altitude long-endurance (HALE) solar aircraft has made it possible to monitor these radicals continuously in the stratosphere. The slower flight speeds of the HALE aircraft will greatly improve molecule detection sensitivity and spatial resolution. To ensure proper mixing and accurate measurements, a quantitative dissection of the flow dynamics within the instrument architecture is required. Of particular importance are the turbulent behavior and the boundary layer growth, both of which affect measurement quality. The geometry of the NO injector used for titration is studied as a function of its solidity and the flight airspeed, to understand its effect on turbulence and boundary layer growth. A 3D Computational Fluid Dynamics simulation of an Eulerian mixture model is used to analyze the advection-dominated mixing inside the instrument. The injector inside the instrument is found to act as a flow-conditioning device, with a lower solidity causing the downstream flow to be increasingly turbulent. Additionally, a quantitative relationship between the Reynolds number of the inlet air and the volume fraction of the flow is demonstrated. Analysis of the boundary layer dependencies demonstrates that the boundary layer does not encroach on the optical sensing area in any of the cases.
A solvable model of a nonlinear extension of quantum mechanics
Authors: Chodos Alan , Cooper Fred
Published: March 2023

We introduce a particular nonlinear generalization of quantum mechanics which has the property that it is exactly solvable in terms of the eigenvalues and eigenfunctions of the Hamiltonian of the usual linear quantum mechanics problem. We hope that this simple example will elucidate some of the issues of interpreting nonlinear generalization of quantum mechanics that have been put forth to resolve questions about quantum measurement theory.
High temperature and strain dual-parameters fiber sensing based on intermodal interference and femtosecond laser fabricated fiber Bragg grating
Authors: Li Shaode , He Wei , Tan Qimeng , Liu Haochong , Li Zhihan , Zhu Lianqing
Published: March 2023

In this paper, the sensor was proposed by combination of grapefruit photonic crystal fiber (GPCF) and femtosecond laser fabricated fiber Bragg grating (FBG) based on Sagnac interferometer. The GPCF was sandwiched between two single-mode fibers (SMFS) to form a SMF-GPCF-SMF structure, which was based on intermodal interference. The FBG with a central wavelength of 1535.32 nm was inscribed through polyimide coating and cladding by the femtosecond laser point-by-point inscribing method. The spectrum drift data of sensing structure were collected and the dual-parameters matrix of temperature-strain was constructed to realize the simultaneous measurement of temperature and strain. The experimental results showed that the linear range of the strain measurement was from 0 με to 2,000 με at different temperature, the wavelength of FBG and GPCF was red drift and blue drift, respectively, the average strain sensitivity at different temperature was 1.25 pm/με and −2.05 pm/με, all the linearity R2 are higher than 0.999, and has the high repeatability. The linear range of temperature measurement was from 20 °C to 450 °C, the wavelength of FBG and GPCF was red drift and blue drift, respectively, the temperature sensitivity of FBG and GPCF was 15.17 pm °C−1 and −8.87 pm °C−1, the linearity was 0.99983 and 0.99989, respectively.
Nonreciprocal Su-Schrieffer-Heeger lattice in the presence of next-nearest-neighboring coupling
Authors: Zhou Wei-Hua , Zhang Chun-Xia
Published: March 2023

We pay attention to the band structure of the nonreciprocal Su-Schrieffer-Heeger (SSH) lattice modified by next-nearest-neighboring (NNN) coupling. It is found that the NNN coupling induces the chiral symmetry by breaking the particle-hole symmetry, leading to the energies of the end modes in the topologically-nontrivial region dependent on the structural parameters. Also, with the increase of NNN coupling, the encounter of the bulk bands modifies the phase transition manner in a new way. The other phenomenon lies in that the localization of the end modes and the non-Hermitian skin effect can be modulated efficiently by the interplay between the NNN and nonreciprocal couplings. Based on these results, one can understand the nontrivial role of NNN coupling in modifying the energy bands and topological properties of the nonreciprocal SSH lattice.
Measurement of hyperfine constants and the isotope shift of rubidium 5P1/2 excited-state using saturated absorption spectroscopy
Authors: Rupasinghe P M , Wee Fiona , Bullock Thomas , Liu Jiaxing
Published: March 2023

The Saturated Absorption Spectroscopy (SAS) was performed to measure the hyperfine constants of rubidium 5P1/2 excited state using an external-cavity diode laser (ECDL) operating at 795 nm. We report our measurements for the magnetic dipole coupling constants 120.79(29) and 407.75(57) for 85
Rb and 87
Rb respectively. Our measurement of the 85
Rb hyperfine constant shows a good agreement with previous results and our measurement of the 87
Rb hyperfine constant resolves the discrepancy of results that exists in the literature.
Quantum noise of diode laser radiation
Authors: Nadezhdinskii A I , Ponurovskii Ya Ya
Published: March 2023

Semiconductors lasers from several manufacturers have been investigated. Rate equations were proposed to describe the dynamics and explain the mechanisms of the appearance of quantum noise in diode lasers. Stationary solutions of the rate equations were obtained. For the lasers under study, the threshold currents and the number of photons at the threshold are obtained. Four mechanisms of the quantum noises appearance were described: Poisson noises of the photons, Poisson noises of the electrons, shot noises of the pump current, and quantum noise of the radiation field. The photon lifetimes for the investigated diode lasers have been determined. The shot noise of the pumping current does not play a significant role. The Poisson noise of photons is responsible for the maximum noise at the generation threshold of a diode laser. The analysis of quantum noises of quantum-cascade diode lasers is carried out.
The First Multiband Photometric Light Curve Solutions of the V Gru Binary System from the Southern Hemisphere
Authors: Tanriver Mehmet , Poro Atila , Bulut Ahmet , Keskin Ahmet , Blackford Mark G.
Published: March 2023

The first multiband photometric solutions of the short-period V Gru eclipsing binary from the southern hemisphere are presented in this study. Light curves of the system were observed through BVI filters at the Congarinni Observatory in Australia for 15 nights. In addition to the new ground-based data, we also used the TESS observations in two sectors. We analyzed the light curves of the system using the PHysics Of Eclipsing BinariEs (PHOEBE) 2.4.7 version code to achieve the best accordance with the photometric observations. The solutions suggest that V Gru is a near-contact binary system with q = 1.302(81) mass ratio, f
1 = 0.010(23), f
2 = −0.0.009(21), and i = 73.45(38). We considered the two hot spots on the hotter and cooler components for the light curve analysis. We extracted the minima times from the light curves based on the Markov Chain Monte Carlo (MCMC) approach. Using our new light curves, TESS, and additional literature minima, we computed the ephemeris of V Gru. The system’s eclipse timing variation trend was determined using the MCMC method. This system is a good and challenging case for future studies.
Various edge low-frequency fluctuations during transition to a detached divertor in Experimental Advanced Superconducting Tokamak
Authors: Ding G.F. , Chen R. , Ye Y. , Xu G.S. , Wu X.Q. , Yang Q.Q. , Yu L. , Meng L.Y. , Wang L. , Lin X. , Wang P. , Lan H.
Published: March 2023

Various edge low-frequency fluctuations with distinct characteristics exist in different detached divertor states. Three edge low-frequency fluctuations (

f
<

10 kHz), namely low-frequency quasi-coherent fluctuation (LFCF), low-frequency broadband frequency fluctuation (LFBF), and low-n X-point mode (LNXM) on Experimental Advanced Superconducting Tokamak (EAST), are systematically assessed. The basic features of these fluctuations, such as spectral width, location, mode number, propagating direction, and particle transport capacities, are examined. LFCF occurs when the inner strike point is energy detached or nearly energy detached with

T

et

,

inner

∼

8–15 eV (

T

et,inner

is the electron temperature of the inner strike point), and a large electron temperature gap between the inner and outer strike points

with 

Δ

T

et

>

25 eV (

Δ

T

et

is the electron temperature gap between the inner and outer strike points) is essential for the occurrence of LFCF. By contrast, LFBF occurs when the inner strike point is energy detached with

T

et

,

inner

<

8 eV, while the outer strike point is nearly energy detached or attached. The

Δ

T

et

of LFBF is generally lower than that of LFCF, which is

<

25 eV. LNXM is related only to the radiative divertor with impurity seeding and considered to be excited by the geodesic acoustic mode proposed in earlier work (Sun 2021 Nucl. Fusion
61 014002; Diallo 2020 28th IAEA Fusion Energy Conf.), or the coupling of impurity radiation condensation instability and drift waves proposed in a previous work (Ye 2021 Nucl. Fusion
61 116032). In addition, the possible physical mechanisms of LFBF and LFCF are proposed, with LFBF being the purely growing rippling mode and LFCF being the mode formed by the coupling of the rippling mode to the drift waves. Related research may be beneficial to better clarify the various low-frequency fluctuations that occur during different divertor states.
The Distance Spectral Radii of Hypercacti
Authors: Zhang Hongxiao , Zhang Lei , Ren Haizhen
Published: March 2023

Hypergraphs can model many concepts in computer science, engineering, psychology, etc. The spectral theory is an important research topic, which is widely used in combinatorial mathematics, computer science and social science. This paper mainly concerns the structure of extremal hypergraphs determined by the distance spectral of hypergraphs. A hypercactus is a connected k-uniform hypergraph with any two cycles sharing at most one common vertex. For hypercacti with a fixed number of vertices and cycles, we completely determine the hypercactus structure with minimum distance spectral radius.
Numerical Solution of Backward Problem of a Multi-term Time-space Fractional Diffusion Equation
Authors: Yang Yuxuan , Li Yushan , Qin Xianru
Published: March 2023

There have been many studies from a variety of perspectives about the fractional diffusion equation for the backward problem. This work looks at the backward problem in a multi-term time-space fractional diffusion equation (TSFDE), which uses the observational final data. This paper proposes a numerical solution based on a Tikhonov regularization technique combined with an optimal perturbation algorithm (OPA) to take care of this poorly posed problem. An implicit finite difference technology is introduced by the matrix transfer technique as a numerical approach to solving the problem of the initial boundary value. It is both highly effective and relatively stable, as our suggested numerical method’s numerical results illustrate.
Estimation of Relative Attitude Information of Cooperative Nodes in UAV Cluster
Authors: Wang Jiyuan , Liu Yilin , Lin Yufan , Song Chuanfei , Yue Zhongmin , Liu Daxue
Published: March 2023

In the collaborative UAV swarm, every node could locate accurately by sharing the accurate navigation information from the leader, through the spatial geometric constraints structured by relative observation. However, the attitude of the followers which only carry cheap navigation sensors can not be optimized through this method. Low-precision attitude system has wide application prospects in military and civil fields such as robots, UUV and UAV, but the existing filtering methods cannot maintain high accuracy of attitude when the carrier move for a long time or maneuvers with high dynamics. This paper provides a method to obtain the relative attitude Euler Angle between the leader and the follower using the visual vector obtained by binocular camera and the target recognition algorithm. In this paper, the simulation and experiment of the proposed method are carried out. The experimental results show that under the good visual conditions, the relative attitude Euler Angle error obtained by identifying distinguishable targets is less than 2 degrees, which meets the demand of attitude determination for cooperative navigation.
Quantile-based Clustering for Functional Data via Modelling Functional Principal Components Scores
Authors: Hael Mohanned A. , Qiang Ma Hai , AL-kuhali Hamas A. , Rizk Zeinab
Published: March 2023

Clustering tasks of functional data arise naturally in many applications, and efficient classification approaches are needed to find groups. The current paper combines the quantile-based model with the principal component analysis of functional data (FPCA). In our proposed procedures, the projection of functional data is first approximated based on (rotated) FPCA. The quantile-based model is then implemented on the space of rotated scores to identify the potential features of underlying clusters. The proposed method overcomes the limitation of using direct basis function expansion such as Fourier, B-spline, or linear fitting, besides representing a nonparametric clustering alternative based on a quantile approach. The proposed method’s performance has been evaluated in a comprehensive simulation study and afterward compared with existing functional and non-functional clustering methods. The simulation study results showed that the proposed method performs well in terms of correct classification rate and computing time average. Finally, a real-world application concerning temporal wind speed data has been analyzed to demonstrate the proposed method’s advantages and usefulness.
Research on Deformation Law of Loess Layer with Buried Pipeline under Earthquake
Authors: Zhang Simeng , Zhang Yong , Lv Yumin , Liu Hao , Huo Jiangtao
Published: March 2023

Previous earthquake damage studies have shown that loess has strong seismic vulnerability under strong earthquakes, and the water pipelines buried in loess are prone to engineering disasters due to displacement around the soil. Therefore, it is necessary to study and analyze the deformation law of the loess layer with buried pipelines under earthquake. In this paper, based on the actual project of the water pipeline Hanjiang-to-Weihe River Water Diversion Project, using FLAC3D finite difference software, taking vertical dynamic displacement, dynamic stress, and dynamic acceleration as indexes, the deformation law of loess layer with water pipeline buried under earthquake is studied. The results show that: With the continuous attenuation of seismic wave energy, the dynamic displacement of the model gradually increases from bottom to top, and the maximum displacement is located at the top of the model. After the earthquake, the soil showed obvious uneven settlement, and the uneven settlement gradually decreased with the increase of soil depth. The overall dynamic stress of the model shows a trend of decreasing from top to bottom. Based on the above analysis results, this paper studies the influence of five factors, such as seismic amplitude, Young’s modulus of soil, cohesion, internal friction angle, and pipeline radius, on the seismic subsidence of loess with buried pipelines. The results show that the primary and secondary order of factors influencing seismic subsidence of loess is seismic amplitude, cohesion, internal friction angle, pipeline radius, and Young’s modulus.
Study on Numerical Simulation Approach to Interaction Effects between Ships
Authors: Zhuo Yongqiang , Zhang Xiufeng , Lu Jianhua
Published: March 2023

To forecast the hydrodynamic interference between ships accurately and intuitively so as to study the ship maneuvering considering the effect of ship-ship interaction, it is significant for navigation safety in restricted water. This paper adopted an easy way to fully simulate interference between the ships. By taking advantage of the Computational Fluid Dynamics approach, the governing equations of viscous flow and the equations of motion of the ships are solved. The ship-ship motion induced by the hydrodynamic forces is numerically simulated so as to study the characteristic of the interaction effects between ships. To verify the validity of the present numerical methods, the numerical results about the influences on the hydrodynamic force and moment are illustrated and analyzed. The simulated results are acknowledged by the experienced ship operators.
Dynamics Modeling and Simulation for the Near Space Airship with Pressure Resistance Mechanism
Authors: Shi Zhiguang , Dong Ruonan , Guo Shushan , Guo Zhen , Yang Yujie
Published: March 2023

The key problem of the near space airship is the maintenance of the safe pressure and the formed buoyancy of the capsule caused by helium “over hot / over cold” under the change of external thermal radiation environment during the circadian cycle station-keeping. In order to solve this problem, this paper takes a typical near-space airship with a pressure resistance mechanism as the research object. Firstly, ten-degree freedom describing its motion is determined under reasonable assumptions. Secondly, the multi-body dynamics model of the airship is established based on the second Lagrange equation. Finally, the model is numerically simulated in MATLAB / Simulink. The simulation results show that the multi-body dynamics model of the airship in this paper effectively reflects and simulates the motion characteristics of the near-space airship with a pressure regulating mechanism under the action of the environmental wind field, which provides a theoretical basis for further research of this kind of object.
Automatic Brain Tumour Subregion Segmentation from Multimodal MRIs Fusing Muti-channel and Spatial Features
Authors: Liu Rongsheng , Liu Xiaowei , Peng Chengfeng , Li Anping , Liao Yong
Published: March 2023

It is very necessary for disease diagnosis, monitoring and treatment planning to locate and segment brain tumours from 3D MRI images accurately. 3D segmentation from MRIs means classifying each voxel in 3D space, it is very conducive to the relevant biological measurements and further analysis of the lesion. Until now, brain tumour segmentation from 3D biomedical images has been a challenging worldwide task due to the tumour features’ variousness, which varies part of U-Net and concatenates these features, which are upsampled to the same scale. To grasp the channel weight and ROIs, the bottleneck of the network is an improved dual path attention module, which convergence the advantages of channel attention and spatial attention. The proposed model has been validated in the online dataset of BraTS 2018. The mean dice score of enhancing tumours is 0.772. The mean dice score of the whole tumour is 0.907. The mean dice score of the tumour core is 0.819. The effectiveness of the proposed method is proved by quantitative and qualitative evaluation.
Research on Short-term Time Series Forecasting Method Based on Feature Fusion of Electric Power
Authors: Ru Chuanhong , Qin Jiansong , Lu Peng , Zhou Dongcheng , Zhang Yan
Published: March 2023

In the power industry, time series forecasting has many application scenarios, such as accurate electricity consumption forecasting and load forecasting, which can provide a reference for power grid staff and reduce decision-making costs. To improve the accuracy of short-term load forecasting, this paper proposes a hybrid forecasting model based on an improved encoder-decoder architecture model and a Temporal Convolutional Network. Based on the gate recurrent unit, the model in this paper introduces the encoder-decoder architecture, adds the attention mechanism for improving the prediction accuracy, and performs feature fusion with the Temporal Convolutional Network, building a dual-feature fusion model finally. Experiments show that the method proposed in this paper reduces the evaluation metrics RMSE, MAPE and MAE by 7.7%, 15.2%, and 13.9% respectively compared to the Long Short-Term Memory Networks. Compared with the Temporal Convolutional Network, it is reduced by 2.6%, 4.8%, and 4%.
Paper-based wearable ultra-sensitive strain sensors for fitness monitoring
Authors: Javaid Aqsa , Zulfiqar Muhammad Hamza , Saleem Muhammad Shoaib , Khan Muhammad Atif , Zubair Muhammad , Mehmood Muhammad Qasim , Massoud Yehia
Published: March 2023

Emerging technologies that exhibit features of biodegradability and eco-friendliness are potential game changers. Paper is a cost-effective and easily available material that has proved itself a promising candidate for manufacturing strain sensors due to its easy integration into flexible electronics. In this work, an ultra-sensitive and highly stable strain sensor is presented. Easily available materials are used for sensors development and very easy and simple fabrication. The modified interdigital capacitor structure is fabricated on a simple printing paper, whereas copper tape is used as an electrode material. In the anticipated work, the milestones of high sensitivity, durability, and fast response time are achieved. The proposed flexible strain sensor is eco-friendly, bio-degradable, inexpensive, and responds well to applied strain. The proposed work exhibits a fast response time of 0.56 s. The high gauge factor value of 3040.26 and stability up to 5000 cycles. The proposed prototype has been also implemented on the human body for monitoring physical activities and fitness exercises. The proposed strain sensor is an outstandingly good option for assimilation into wearable systems like remote healthcare systems, electromechanical sensing, and human physical monitoring.
Towards a scalable discrete quantum generative adversarial neural network
Authors: Chaudhary Smit , Huembeli Patrick , MacCormack Ian , Patti Taylor L , Kossaifi Jean , Galda Alexey
Published: March 2023

Quantum generative adversarial networks (QGANs) have been studied in the context of quantum machine learning for several years, but there has not been yet a proposal for a fully QGAN with both, a quantum generator and discriminator. We introduce a fully QGAN intended for use with binary data. The architecture incorporates several features found in other classical and quantum machine learning models, which up to this point had not been used in conjunction. In particular, we incorporate classical noise reuploading in the generator, auxiliary qubits in the discriminator to enhance expressivity, and a direct connection between the generator and discriminator circuits, obviating the need to access the generator’s probability distribution. We show that, as separate components, the generator and discriminator perform as desired. We empirically demonstrate the expressive power of our model on both synthetic data as well as low energy states of an Ising model. Our demonstrations suggest that the model is not only capable of reproducing discrete training data, but also of potentially generalizing from it.
Electrode configuration study for three-dimensional imaging of on-chip ECT
Authors: Hor Xian Feng , Leow Pei Ling , Ali Mohamed Sultan Mohamed , Chee Pei Song , Din Shahrulnizahani Mohammad , Gooi Wen Pin
Published: March 2023

Conventional electrical capacitance tomography (ECT) is widely used for monitoring the fluids flow in a pipeline. As the emergence of microfluidics, the tomography system has been miniaturized and integrated into the microfludic platform for imaging purposes. The on-chip ECT is designed to monitor the permittivity distribution of the micro-platform by integrating the planar electrodes with the sensing region. However, limited research has been reported on the electrode design of on-chip ECT, especially for three-dimensional imaging. Thus, this study investigated the electrode design of an on-chip ECT that is capable for image reconstruction in three-dimensions. Four different electrode configurations with different numbers of electrode and arrangements are investigated by simulation to determine the appropriate configuration for three-dimensional imaging. The electrode dimension is optimized based on the sensitivity distribution using the sensitivity variation parameter (SVP). The simulation results shows that the electrode configuration with dual sensing planes enable three-dimensional imaging. The central electrode of each sensing plane is crucial for restoring a floating object. In experiment, the imaging object that was positioned at different vertical and horizontal locations was reconstructed successfully with an average correlation coefficient of 0.4370 using linear back projection (LBP) algorithm. This work has disclosed the appropriate electrode configuration for the three-dimensional imaging of an on-chip ECT system.
Torus Lorenz links obtained by full twists along torus links
Authors: de Paiva Thiago
Published: March 2023

All knots are known to be hyperbolic, satellite, or torus knots, and one important family is Lorenz links, or T-links, which arise from dynamics. However, it remains difficult to determine the geometric type of a Lorenz link from a description via dynamics or as a T-link. In this paper, we consider those T-links that are torus links. We show that T-links obtained by full twists along torus links can never be torus links, aside from a family of cases. This addresses a question of Birman and Kofman [J. Topol. 2 (2009), pp. 227–248].