bluuebunny/crossref_metadata_2025 huggingface dataset:
Fourier analysis of signal dependent noise images
Authors: Heine John , Fowler Erin , Schabath Matthew B.
Published: December 2024

An archetype signal dependent noise (SDN) model is a component used in analyzing images or signals acquired from different technologies. This model-component may share properties with stationary normal white noise (WN). Measurements from WN images were used as standards for making comparisons with SDN in both the image domain (ID) and Fourier domain (FD). The ID wavelet expansion was applied to WN images (n = 1000). Orthogonality conditions were used to parametrically model the variance decomposition, as described in both domains. FD components were investigated with probability density function modeling and summarized measures. SDN images were constructed by multiplying both simulated and clinical mammograms (both with n = 1000) by WN. The variance decomposition for both WN and SDN decreases exponentially as a parametric function of the ID expansion level; expansion image variances for both types of noise were captured similarly in the Fourier plane corresponding with the ID parametric model. The Fourier transform of WN has a uniform power spectrum distributed exponentially; SDN has similar attributes. Fourier inversion of the lag-autocorrelation performed in the FD produced a statistical estimation of the SDN’s image factor. These findings are counterintuitive as SDN can be nonstationary in the ID but have stationary attributes in the FD.
Photoabsorption of silver cluster cations in an ion trap: nonlinear action spectra via multi-photon dissociation vs. directly measured linear absorption spectra
Authors: Kono Satoshi , Fujimoto Shuhei , Ito Tomonori , Arakawa Masashi , Horio Takuya , Terasaki Akira
Published: December 2024

Multi-photon dissociation emerges in large clusters due to rapid cooling in an ion trap, causing difficulty in obtaining linear absorption spectra by photodissociation spectroscopy. Cavity-ring down spectroscopy works even for such large sizes.
Hybridization of magnetization oscillations and the profile of the free surface in an 3He-A1 film
Authors: Baramidze G. A. , Gurenishvili G. E. , Kharadze G. A.
Published: December 2024

Collective oscillations in a film of superfluid 3He-A placed in a strong magnetic field are considered for the case ρ = const and in the vicinity of the A → A1 transition. It is shown that near the transition to the A1 phase oscillations of the longitudinal magnetization mix with oscillations of the profile of the free surface of the film and the hybrid wave propagates with a velocity of the order of (ρn/ ρ)1/2usp, where usp is the spin-wave velocity in the bulk of the 3He-A.
Frequency dependence of impedance oscillations in tungsten plates in a magnetic field perpendicular to the surface
Authors: Zherebchevskii D. E. , Naberezhnykh V. P. , Chabanenko V. V.
Published: December 2024

The dependence of the amplitude of size effects in the impedance of tungsten plates placed in a magnetic field oriented perpendicular to the surface on the frequency of the external wave in the range 3 MHz–900 Hz for symmetrical and antisymmetrical methods of excitation is studied experimentally. A substantial lowering of the frequency of the external wave enabled the observation of a continuous transition in the experiment from radio-frequency size effects to the quasistationary Sondheimer effect. Theoretical analysis of the ratio of the amplitudes of size effects in the impedance together with the experimental results enabled an accurate physical interpretation of the observed oscillations and determination of the region of magnetic fields in which the observed impedance oscillations at radio frequencies can be uniquely identified as Sondheimer oscillations.
Effect of the thickness on the impedance of thin tungsten plates
Authors: Koval’ V. F. , Vatamanyuk V. I. , Ostroukhov Yu. S. , Panchenko O. A.
Published: December 2024

The monotonic part of the impedance of thin tungsten plates with two different crystallographic orientations (n‖ [100] and n‖ [110] in a strong magnetic field is studied as a function of the thickness of the plate d with antisymmetric excitation of the radio-frequency field. The average mean-free path length l and the average normal component of the quasimomentum p⊥ of the carriers, making the main contribution to the effect, are evaluated.
Anomalous galvanomagnetic properties of heteroepitaxial structures p-lnSb/i-GaAs at low temperatures
Authors: Kichigin D. A. , Mironov O. A. , Chistyakov S. V.
Published: December 2024

The quantum corrections to the galvanomagnetic coefficients (the conductivity, Hall’s coefficient, the transverse and longitudinal magnetoresistance) of the quasi-two-dimensional electronic system of a p-InSb/i-GaAs heterojunction in the temperature interval 1.0–10 K and for magnetic fields in the range 10 Oe–50 kOe were studied experimentally. The characteristic inelastic electron relaxation times and the effective thickness of the quasi-two-dimensional layer are calculated, the contributions of localization and interelectronic interaction are separated, and the electron-phonon relaxation of hot quasi-two-dimensional electrons is studied. The phenomenon of frozen-in negative photoconductivity, enabling the control of the parameters of the quasi-two-dimensional layer, was observed. The experimental results are explained on the basis of the theoretical notions regarding localization and interelectronic interaction in disordered systems.
Phase states and spectrum of spin excitations of a weakly anisotropic magnet containing impurities with a strong competing anisotropy
Authors: Ivanov M. A. , Loktev V. M. , Pogorelov Yu. G.
Published: December 2024

The spin configurations of a weakly anisotropic antiferromagnet (ferromagnet) of the “easy axis” type with orthogonal impurities with concentration c≪1 are studied. It is shown that as c is increased the system transforms from the “easy plane” phase through an intermediate so-called corner phase into the “easy axis” phase. The behavior of spin-wave branches for each of the phases is studied, and the criteria of applicability of the usual molecular-field approximation are determined.
Attenuation of ultrasound in thin layers of a normal metal adjacent to a superconductor
Authors: Kolesnichenko Yu. A.
Published: December 2024

The absorption of ultrasound in thin layers of a normal metal adjacent to a superconductor is investigated theoretically. It is shown that the interaction of charge carriers with the normal metal–superconductor boundary induces new magnetoacoustic effects, which can be studied experimentally to obtain information on Andreev reflection.
Quantum anomalies in the phase diagrams of easy-plane antiferromagnets in a magnetic field
Authors: Borisenko V. G. , Pereverzev Yu. V.
Published: December 2024

We obtain the phase boundaries for easy-plane antiferromagnets with a single-ion anisotropy in a longitudinal magnetic field under a molecular field approximation for arbitrary values of the spin and the ratio of the anisotropy to the exchange. It is shown that for a finite spin S the phase diagram exhibits anomalies which disappear in the classical limit S → ∞.
Dysprosium ethylsulfate: a dipolar Ising magnet
Authors: Favorskii I. A.
Published: December 2024

We have studied the phase transition in the low temperature ferromagnet Dy(C2H5SO4)3 · 9H2O using the Monte-Carlo method with rigorous account of the dipole interaction between the spins and using no adjustable parameters. Better agreement with experiment is observed for | (T − Tc)/Tc | ≳ 0.1. On the basis of the Monte-Carlo data we discuss the nature of the cooperative phenomena in Dy(C2H5SO4)3 · 9H2O and the reasons for the significant discrepancies with the results of a self-consistent field approach.
Four-sublattice model of a biaxial antiferromagnet and its comparison with experiment
Authors: Dan’shin N. K. , Zel’tser A. S. , Popov V. A.
Published: December 2024

Utilizing a four-sublattice model that takes account of the Dzyaloshinskii interaction and the tensor nature of the g-factor for spectroscopic splitting, we consider the ground states and frequency–field dependences of the antiferromagnetic resonance of a biaxial antiferromagnet at T = 0 in a magnetic field parallel to the “easy” antiferromagnetism axis. It is shown that the effect of the Dzyaloshinskii interaction and the anisotropy of the g-factor may be reduced to a renormalization of the frequency–field dependences of the antiferromagnetic resonance parameters of the two-sublattice model only for the case of small fields. Expressions are obtained that make possible a self-consistent determination of the phenomenological parameters of the four-sublattice model through the use of experimental antiferromagnetic resonance data. An analysis of experimental microwave and IR absorption data is carried out in terms of the proposed model for the case of the antiferromagnet CuCl2 · 2H2O.
Optical properties of metals with helium crystallized in their pores
Authors: Golineĩ I. Yu. , Sugakov V. I.
Published: December 2024

The absorption of electromagnetic waves at low temperatures in metals filled with helium has been studied theoretically in the region of the atomic helium 1S0–21P1 transition. It is suggested that as a result of the high pressure the helium in the pores exists in the crystallized form and its excited states are excitons. The permittivity of a medium containing pores with helium has been found. The frequency dependence of the absorption contains maxima produced by the discrete nature of the exciton spectrum in a pore. The most intense resonances in the absorption occur for those discrete levels which are positioned closest to the region of the eigen frequency of the oscillations of a sphere without spatial dispersion. An experimental study of the discrete structure of the absorption spectrum would enable the parameters of the exciton band of crystalline helium to be determined.
Stability of a shock wave in superfluid helium
Authors: Nemirovskii S. K.
Published: December 2024

The stability of a shock wave in superfluid helium against small perturbations of the first- and second-sound modes is investigated. As a result of solving the linearized equations for small shock-type flow corrections, it is shown that a pressure shock wave is stable against temperature perturbations (second sound), pressure perturbations (first sound), and small distortions of the shock front surface.
Conversion in solid solutions of deuterium and hydrogen
Authors: Strzhemechnyi M. A. , Tokar’ O. I.
Published: December 2024

We consider the mechanisms of conversion in solid solutions of H2 and D2. It is shown that the conversion processes for the D2 molecules should be accompanied by the emission of a single phonon, while those for H2 should involve two. A new conversion mechanism is proposed, which is to be found only in solutions in which a rotational excitation is transferred from a molecule of o-H2 to a molecule of o-D2 and the energy difference is emitted as a phonon. Estimates are presented for all the conversion mechanisms discussed, and it is shown that the single-phonon probability for conversion of D2 provides better agreement with experiment than the two-phonon probability calculated by Motizuki. The possibility of experimental observation of the proposed cascade mechanism is discussed.
Mechanism of resistivity in wide superconducting films
Authors: Moskvin S. I.
Published: December 2024

The characteristics of a superconducting transformer consisting of wide granular aluminum films in the region where the phase of the wave function of the condensate changes by a mechanism of the phase-slip line type (PSL) are studied. It is shown that the superconducting transformer method enables the spatial resolution of PSL as a region where there is no motion of Abrikosov vortices. The ratio of the additional differential resistances associated with PSL enable us to draw the conclusion that a supercurrent flows through the region of PSL.
Asymmetry of the current–voltage characteristics of metal–metal point contacts as the result of phonon drag
Authors: Itskovich I. F. , Kulik I. O. , Shekhter R. I.
Published: December 2024

The thermoelectric effect of the phonon drag in an asymmetric point contact between normal metals is considered in the diffusion and thermal limits. It is shown to lead to an asymmetric nonlinear contribution to the current–voltage characteristic, whose relative value is proportional to the phonon elastic scattering length and increases with decreasing electron mean free path.
Nature of the anomalous isotopic effect for the superconducting transition temperature of PdHx(Dx)
Authors: Zhernov A. P. , Drekhsler Sh. L.
Published: December 2024

The question of the nature of the anomalous isotopic effect (AIE) for Tc in the metals PdHx and PdDx is studied. It is shown that when only the anharmonicity in the oscillations of H and D is taken into account, the scale of the AIE cannot be correctly described. It is found that the effective Coulomb and electron–paramagnon interactions play an important role. A specific analysis is carried out based on an approximate solution of the Burke–Schrieffer equation for Tc. In addition to the AIE, the pressure dependence of Tc and the change in AIE accompanying a deviation from the stoichiometric composition are described quantitatively.
Penetration of a magnetic field into a superconductor without an inversion center
Authors: Nazarov Yu. V.
Published: December 2024

Effects connected with the penetration of a magnetic field and peculiar to superconductors without an inversion center are investigated. The relation between these effects and the microscopic properties of the superconducting material is investigated in detail.
Nonequilibrium current-carrying states in metallic point contacts
Authors: Kulik I. O.
Published: December 2024

Nonequilibrium phenomena in the electron-phonon system of a normal metal in the current-carrying state under the conditions of strong current concentration are studied. It is shown that for a short phonon momentum mean-free path length lr < d in a point contact with diameter d which is small compared with the phonon and electron energy relaxation lengths lph and le, a nonequilibrium phonon distribution differing from a Planck distribution with an effective temperature of Θ∼eV/4 is established. This gives rise to “nonspectral” corrections to the current-voltage characteristic (the so-called background in point-contact spectra) and to a substantial frequency dispersion of the nonlinear conductivity of the point contact in the region of relatively low frequencies ω ∼ νph∼λ (s/υF) ωD ∼ 1010–1011 sec−1. Study of the latter enables not only determining with the help of point-contact spectroscopy the electron-phonon interaction function g(ω) = α2F(ω), but it also enables obtaining direct information on relaxation rates of Debye phonons in the metal. The background formed by nonequilibrium phonons in point-contact spectra is absent at frequencies ω ≫ νph.
Spontaneous magnetoelectric effects in cubic ferromagnetoelectrics
Authors: Chupis I. E.
Published: December 2024

The interrelationship between the orientations of the spontaneous polarization and spontaneous magnetization in ferro(ferri)magnetoelectric crystals with a centrosymmetric cubic paraelectric phase whose ferroelectric transition temperature is lower than the critical temperature for the magnetic ordering is studied. Exact solutions are obtained for the equilibrium moments for any values of the energy parameters. It is shown that the magnetoelectric interaction determines the direction of the electric polarization in a magnetic domain. At lower temperatures first- or second-order phase transitions induced by the magnetoelectric interaction can lead to the reorientation of the moments. As a result of the appearance of the polarization, the magnetization may undergo a 45° deflection in a coordinate plane, or change its orientation from alignment along a coordinate axis to alignment along the cube body diagonal (e.g., ⟨001⟩ ⟶⟨111⟩).
Excitation of Josephson generation in an SNS junction by a longitudinal electric field
Authors: Kaplunenko V. K. , Ryazanov V. V.
Published: December 2024

In the absence of transport current Josephson effects have been observed in an SNS junction upon injection of quasiparticles into one of the superconducting banks (electrodes). These effects are believed to be caused by the penetration of the longitudinal electric field into the region of the junction.
Identifying factors influencing electric vehicle adoption in sub-Saharan Africa
Authors: Thompson Avery
Published: December 2024

Understanding the most significant obstacles can lead to policy changes, increases in EV adoption rate in developing countries
Phase transitions in the non-stationary lattice Anderson model
Authors: Chen Xiaoyun , Han Dan , Molchanov Stanislav A.
Published: December 2024

We study the non-stationary Anderson parabolic problem on the lattice Zd, i.e., the equation ∂u∂t=ϰAu(t,x)+ξt(x)u(t,x),u(0,x)≡1,(t,x)∈[0,∞)×Zd. Here A is a non-local difference operator, ξt(x), t ≥ 0, x ∈ Zd, is the family of the correlated white noises and ϰ > 0 is the diffusion coefficient. The changes of ϰ (large vs small) are responsible for the qualitative phase transition in the model. At the first step the analysis of the model is reduced to the solution of the stochastic differential equation (in the standard Itô’s form) on the weighted Hilbert space l2(Zd, μ) with an appropriate measure μ. The equations of first two moments of the solution u(t, x) are derived and studied using the spectral analysis of the corresponding Schrödinger operators with special class of the positive definite potentials. The analysis reveals several bifurcations depending on the properties of the kernel of A and the correlation function in the potential.
Modeling interface roughness scattering with incorporation of potential energy and wave-function fluctuations: Enhancing mobility in AlN/GaN digital alloys
Authors: Hong Gongyi , Chaney Alexander , Charnas Adam , Kim Yunjo , Asel Thaddeus J. , Neal Adam T. , Mou Shin
Published: December 2024

Interface roughness (IFR) scattering significantly impacts the mobility of two-dimensional electron gases (2DEGs) in heterostructures. While existing models for IFR scattering have advanced our understanding, they have notable limitations. The model developed by Jin et al. in 2007, while incorporating a realistic barrier height and roughness-induced changes in potential and subband wave-functions, employs a first-order roughness expansion. The formulation introduced by Lizzit et al. in 2014, although avoiding the first-order approximation for better higher-order effect modeling, omits IFR-induced change in electron density distribution. To address these limitations, we introduce a novel model that comprehensively accounts for all IFR-induced effects while avoiding any expansion approximations, by incorporating IFR-modified subband energies and wave-functions obtained from the numerical solution of the Schrödinger equation during the calculation of IFR scattering matrix elements. In addition, we have included models for other relevant scattering mechanisms, including charged dislocation lines, ionized impurities, acoustic phonons, and polar optical phonons. A comprehensive numerical analysis of carrier mobility has been performed for an AlN/GaN high electron mobility transistor, yielding results consistent with experimental data. Furthermore, to investigate the impact of device architecture on 2DEG mobility, we study the effects of layer thickness and modulation doping profiles in AlN/GaN digital alloys. Our findings reveal strategies for engineering high mobility at elevated 2DEG concentrations, potentially advancing the development of high-performance semiconductor devices.
On the R-matrix realization of the quantum loop algebra. The case of Uq(Dn(2))
Authors: Liashyk A. , Pakuliak S.
Published: December 2024

The connection between the R-matrix realization and Drinfeld’s realization of the quantum loop algebra Uq(Dn(2)) is considered using the Gaussian decomposition approach proposed in Ding and Frenkel [Isomorphism of two realizations of quantum affine algebra Uq(gl̂(n)), Commun. Math. Phys. 156, 277 (1993)]. Our main result is a description of the embedding homomorphism which relates the quantum affine algebra of rank n − 1 with a subalgebra of the corresponding algebra of rank n. Explicit relations between all Gaussian coordinates of the L-operators and the currents are presented.
Band alignment in Zn(1−x)MgxO:Al/SiOx/Si heterostructures for photovoltaic applications realized by atomic layer deposition: Effects of Al doping and Mg alloying
Authors: Schifano R. , Gieraltowska S. , Kurek J. , Wachnicki L. , Rehman U. , Budiakivska D. , Chusnutdinow S. , Kopalko K. , Porro S. , Jakiela R. , Minikayev R. , Witkowski B. S. , Pawlowski M. , Jastrzebski C. , Thøgersen A.
Published: December 2024

In this work, the impact of Al doping and Mg alloying on the conduction band misalignment (ΔEC) between ZnO and (100) Si with a SiOx interlayer was studied by combining capacitance vs voltage, Hall and x-ray diffraction measurements, energy-dispersive x-ray spectroscopy, secondary mass spectrometry, and high-resolution scanning transmission electron microscopy. To decouple the effect of the high carrier density in the ZnO-based layers due to the Al introduction, the measured ΔEC was corrected for the conduction band lowering effect taking into account the conduction band non-parabolicity of ZnO. Then, from the Mg content dependence, using the interface-induced gap states approach, branch point energies referred to the valence band maximum equal to (2.7±0.2) and (3.6±0.4) eV were extracted for ZnO and MgO, respectively. These branch point energies were obtained under the assumption of a linear variation between the respective values of the corresponding two binary compound semiconductors, ZnO and MgO, and taking into account the presence of the SiOx interlayer. Furthermore, in the case of the undoped Zn0.96Mg0.04O layers, a ∼0.27 eV reduced ΔEC was found, with the difference with respect to Zn0.94Mg0.06O:Al attributed to the presence of a downward band bending toward the interface with SiOx. Full 1 × 1 cm test solar cells based on Zn0.8Mg0.2O:Al layers exhibited short circuit currents, open circuit voltages, fill factors, and efficiencies that varied in the (28±1)mA/cm2, (430±20) mV, (61±2)%, and (7.2±0.3)% ranges with the residual ΔEC∼0.6 eV being among the main causes of the reduced device performances.
Development of optical emission spectroscopy method with neural network model: Case study of determining the electron density in a xenon microwave discharge
Authors: Wang Yan-Fei , Zhu Xi-Ming
Published: December 2024

Optical emission spectroscopy (OES) is an important technique for plasma diagnostics. Random deviation is inevitable during the measurement of plasma emission spectra due to the imperfection of instruments and other interferences. On the other hand, inaccuracies in the collision cross-section data can lead to distortion of the collisional-radiative (CR) model. The coupling of theoretical and experimental error factors can pose difficulties for accurate diagnostics of plasma. This work presents the development of the OES method for xenon plasma that employs a neural network model to integrate prior information on the characteristics of instrument noise and model distortions, thereby improving the accuracy of OES diagnostics. The neural network model takes emission line ratios as input and normalized electron density as output and is trained using a dataset that is generated with a CR model and an instrument disturbance model. The neural network-based OES method is implemented to determine the electron density in a microwave discharge chamber and compared with a traditional OES method with a multi-variant fitting technique. A significant improvement on relative deviation of diagnostic results is observed, which promises a good prospect for further development.
Advances in artificial intelligence for artificial metamaterials
Authors: Si Liming , Niu Rong , Dang Chenyang , Bao Xiue , Zhuang Yaqiang , Zhu Weiren
Published: December 2024

The 2024 Nobel Prizes in Physics and Chemistry were awarded for foundational discoveries and inventions enabling machine learning through artificial neural networks. Artificial intelligence (AI) and artificial metamaterials are two cutting-edge technologies that have shown significant advancements and applications in various fields. AI, with its roots tracing back to Alan Turing’s seminal work, has undergone remarkable evolution over decades, with key advancements including the Turing Test, expert systems, deep learning, and the emergence of multimodal AI models. Electromagnetic wave control, critical for scientific research and industrial applications, has been significantly broadened by artificial metamaterials. This review explores the synergistic integration of AI and artificial metamaterials, emphasizing how AI accelerates the design and functionality of artificial materials, while novel physical neural networks constructed from artificial metamaterials significantly enhance AI’s computational speed and its ability to solve complex physical problems. This paper provides a detailed discussion of AI-based forward prediction and inverse design principles and applications in metamaterial design. It also examines the potential of big-data-driven AI methods in addressing challenges in metamaterial design. In addition, this review delves into the role of artificial metamaterials in advancing AI, focusing on the progress of electromagnetic physical neural networks in optics, terahertz, and microwaves. Emphasizing the transformative impact of the intersection between AI and artificial metamaterials, this review underscores significant improvements in efficiency, accuracy, and applicability. The collaborative development of AI and artificial metamaterials accelerates the metamaterial design process and opens new possibilities for innovations in photonics, communications, radars, and sensing.
Vertical GaN Schottky barrier diodes with micrometer pillar Schottky contacts
Authors: Zhu Renqiang , Li Bo , Li Shuai , Ma Zhengweng , Yang Huakai , He Shijie , Huang Shuangwu , Xiong Xinbo , Chiu Hsien-Chin , Li Xiaohua , Zhang Bo , Liu Xinke
Published: December 2024

We present a novel design of gallium nitride (GaN) Schottky barrier diodes (SBDs) with a vertical micropillar structure. The micron-scale electrode design can effectively enhance the on-state current density and reduce the specific on-resistance (R
on,Sp). In addition, it allows for a reduction in the turn-on voltage (V
on) by minimizing the spacing between the electrodes. This phenomenon can be explained by the intensified electric field coupling between the electrodes, as confirmed from the technology computer aided design simulations. By controlling the distance between the micron pillars, the V
on of the SBD varies from approximately 0.35 V to 0.46 V. These results showcase the potential of our SBD design with micropillar contacts in efficient high-power applications.
Influence of Pt doping on magnetic and electronic properties in NiFe thin films
Authors: Aksu Perihan , Pişkin Hasan
Published: December 2024

Several applications in nowadays spintronics require new materials with a lower coercive field, higher spin damping parameter, and lower Curie temperature to manipulate its magnetization via injected spin currents (spin-transfer torque or spin–orbit torque) with a faster magnetization switching. Besides, for the anisotropic magnetoresistance (AMR)-based magnetic field sensors, the materials that have softer magnetic properties and higher AMR differences (

Δ
R
=

R
∥

−
R
⊥

) are valuable to enhance the sensor’s magnetic field sensitivity and signal’s readability. In this regard, the tunability of magneto-static, magneto-dynamic, and electronic properties of Ni80Fe20 alloy diluted with Pt have been systematically investigated in the present work. For the (Ni80Fe20)(1−x)Pt(x) ternary alloys, x were varied between 0 and 0.6. The experimental results show that the use of ∼15% Pt is beneficial to enhance the AMR difference with a lower coercive field. Furthermore, since the addition of Pt into Ni80Fe20 enhances the Gilbert damping while lowering both the Curie temperature and saturation magnetization, the magnetic moments become more vulnerable to manipulation which is crucial for spintronics-based devices.
Comparison of quantitative analysis models for atmospheric bioaerosols based on mixed fluorescence spectra
Authors: Jian Xiaojiao , He Tingyao , Li Jiaojiao
Published: December 2024

Real-time monitoring of atmospheric bioaerosol concentrations primarily involves analyzing the total fluorescence signal, which does not provide the specific content of each component. Since mixed fluorescence spectra contain information about the composition and content of bioaerosols, by employing multivariate analysis of the spectra and using multivariate regression algorithms, it is possible to extract the components from the mixed spectra and predict the proportion of each component. In this study, upon the extracted components in the mixed fluorescence spectra by vertex component analysis, we compared several quantitative analysis models for their accuracy in predicting bioaerosol proportions. The models can obtain the proportion of each component effectively when three components exist in the mixed spectra, with 2D convolutional neural networks (CNNs) having the best effect. To ascertain the algorithms’ stability, discussions on scenarios involving multiple components (four-component and five-component mixtures) as well as low-frequency noise conditions have also been included. The degree of impact on Bacillus Subtilis is the biggest when the number of mixed components increased. For the CNNs, the interference caused by the increase in the number of components is relatively higher than that of low frequency noise. When the number of the component is increased, the prediction effect of the algorithms is affected with considerable low frequency noise. Principal component regression and back propagation neural networks can maintain a relatively stable and reliable prediction effect. It is possible to match the most suitable algorithms for different components, thereby obtaining more accurate measurement results and providing a certain reference value for the detection of bioaerosol concentrations.
A two-layer optimal scheduling method for microgrids based on adaptive stochastic model predictive control
Authors: Hu Jinxing , Yan Pengqian , Tan Guoqiang
Published: December 2024

Renewable energy is highly susceptible to weather and environmental factors, and changes dramatically in a short period, which makes it difficult for traditional fixed-period scheduling of microgrids to capture the time-series variations of source and load, exacerbating the power imbalances of systems. To address this problem, a novel two-layer rolling optimization framework for microgrids based on adaptive stochastic model predictive control is proposed in this paper. Firstly, a two-layer microgrid optimization model based on stochastic model predictive control is established, in which measurement technology plays an indispensable role in the quality of uncertain scenarios and optimal decision results of the microgrid, as well as providing impetus for the development of the microgrid. In the upper-layer prescheduling stage, the optimal control sequence under multiple uncertainties is obtained by solving a scenario-based chance constraint programming model. In the lower-layer power compensation stage, the measured scenario errors are regarded as fluctuations, and the energy storage devices are preferentially used for smoothing processing. Secondly, an adaptive period division method using Wasserstein distance-based hierarchical clustering is developed to guide intraday online scheduling. The concepts of distribution similarity and distribution loss are presented to adaptively divide the periods under uncertain conditions, so as to overcome the disturbance of uncertainty and improve the flexibility of microgrid scheduling. Finally, the simulation results show that the proposed method can flexibly deal with the uncertainty at different time scales, and achieve 53.63 kWh less compensation power and 19.12% lower operating cost than traditional fixed-period scheduling methods, and thus effectively improve the economy and reliability of microgrid operation.
Extension of measurable velocity limit of ultrasonic velocity profiling based on phase difference gradient analysis
Authors: Shoji Naruki
Published: December 2024

A signal processing method, called the ultrasonic cross-spectrum method, is proposed to extend the measurable velocity limit of ultrasonic velocity profiling. It focuses on the phase difference spectrum within the signal bandwidth and extends the velocity limit by analyzing its gradient. The algorithmic performance is confirmed via echo signal simulation and experimental pipe flow measurement. Consequently, setting a threshold for the coefficient of determination for phase-difference spectrum fitting enables us to reduce the false velocity detection rate to <1.6% and achieve an effective data rate of 42% in low signal-to-noise ratio conditions. This data rate is twice that of a conventional method. Moreover, a comparison of pipe flow results between our method and particle image velocimetry shows that the velocity data difference is within ±2% for a velocity range twice the conventional measurable velocity limit. In short, we demonstrate the potential of this method for high-performance velocity profiling.
Investigation on the spatial distribution of H− ions in RF ICP source with Faraday shield
Authors: Chen Chao , Zhai Wenzhi , Wang Qiang , Liu Dongping , Lei Guangjiu , Ni Weiyuan , Zhao Miao
Published: December 2024

For the realization of magnetic confinement fusion, the negative hydrogen ions produced by an radio frequency (RF) ICP (inductively coupled plasma) source are employed for neutralization process of the neutral beam injection system. A 3D fluid model tailored for the RF ICP source has been developed to explore the negative hydrogen ion distribution. The negative hydrogen ion source consists of the cylindrical driver containing Faraday shield (FS) and the expansion chamber equipped with permanent magnets. The study is focused on the influences of FS, pressure (0.5–2.0 Pa) and permanent magnet remanence (0–1.03 T) on the negative hydrogen ions distribution. When the FS is applied in the driver, the negative hydrogen ion density is low owing to the high electron temperature. The maximum density of the negative hydrogen ions rises monotonically and shifts to the driver with the increased gas pressure. The distribution of negative hydrogen ions is dominated by transport processes at low pressures, while the collision processes become significant at high pressures. The density of negative hydrogen ions near the plasm grid increases with the transverse magnetic filter (TMF) strength as a result of the decreased temperature of electrons. The asymmetry in the density of negative hydrogen ion is enhanced with the increased TMF strength. Our current model offers valuable insights into the behavior of negative hydrogen ions within RF ICP source, thereby advancing our comprehension of this critical component in fusion engineering.
Crack sensing in reinforced concrete beams and reinforced concrete pipes based on self-sensing cementitious sensors array
Authors: Yu Xianming , Yao Yao
Published: December 2024

To enable the smart monitoring of crack sensing in reinforced concrete structures using self-sensing cementitious sensors (SSCSs), this study quantified crack information based on changes in the electrical signals of SSCS. The location of cracks was evaluated based on changes in the electrical signals of SSCS. Following this, for the first time, a crack sensing was conducted by embedding an SSCS array into the reinforced concrete pipes. Based on external load tests, both failure tests and cyclic loading tests were conducted on reinforced concrete pipes. The empirical model for crack width was established based on the fractional change in peak electrical resistivity (FCR
P
) and the external load amplitude. The experimental results indicated: (1) the farther the crack was from the SSCS, the smaller the influence on the electrical signal changes of the SSCS. Therefore, the distance of the crack from the SSCS could be estimated by analyzing the changes in the fractional change in electrical resistivity (FCR); (2) for reinforced concrete pipes with existing cracks, both the FCR
P
and the residual FCR of the SSCS increased as the crack width and the amplitude of cyclic loading increased. These parameters could serve as indicators to determine whether a specific section of the concrete pipe has developed cracks; (3) an empirical model for crack width was developed based on the FCR
P
and the load amplitude. The proposed empirical model could effectively reflect the crack width in the concrete pipes by using the FCR
P
values from the SSCS array and the external load amplitude. This study presents a novel method for leakage monitoring in underground concrete pipes using an SSCS array, laying the foundation for their future application in underground concrete pipes.
Sulfur-Coated RGO Composite Synthesized via a Rapid Heating Method for Li-S Battery Application
Authors: shastri Mahesh , Marilingaiah Navyarani , Muniyappa Murthy , Shetty Manjunath , Roy Kunal , Rangappa Dinesh
Published: December 2024

Lithium-sulfur (Li-S) batteries has gained a lot of attention because of its high energy density (2567 Whkg−1), great earth abundance, and low impact on the environment. The excellent theoretical performance of Li-S batteries is compromised by major technical challenges like low sulfur utilization rate, reduced columbic efficiency, and poor cycling stability due to the insulating nature of sulfur and the shuttle effect of soluble lithium polysulfides. To overcome these concerns, herewith, made an attempt to synthesise Sulfur -reduced graphene oxide (S-RGO) nanocomposite by rapid fast heating technique. Using the solution-based rapid heating method, sulfur nanoparticles uniformly distributed on graphene oxide network. Furher, deployed in fabricating Li-S cathode. The S-RGO composite with 80 wt% sulfur exhibits promising results. Initially, at 0.05 C rate discharge current shows 1230 mAh/g capacity and at 0.1 C rate shows 1085 mAh/g. After 50 cycles, the capacity was retained with 1030 mAh/g at 0.05C and 957 mAh/g at 0.1C. This suggests that the the synthesised Li-S nanocomposite exhibit good capacity at higher current rate with greater sulfur content.
Quantum features of the transport through ion channels in the soft knock-on model
Authors: Polakowski Mateusz , Panfil Miłosz
Published: December 2024

Ion channels are protein structures that facilitate the selective passage of ions across the membrane cells of living organisms. They are known for their high conductance and high selectivity. The precise mechanism between these two seemingly contradicting features is not yet firmly established. One possible candidate is the quantum coherence. In this work we study the quantum model of the soft knock-on conduction using the Lindblad equation taking into account the non-hermiticity of the model. We show that the model exhibits a regime in which high conductance coexists with high coherence. Our findings second the role of quantum effects in the transport properties of the ion channels.
Analysis of Biasing from Noise from the Nancy Grace Roman Space Telescope: Implications for Weak Lensing
Authors: Laliotis Katherine , Macbeth Emily , Hirata Christopher M. , Cao 开力 Kaili 曹 , Yamamoto Masaya , Troxel Michael
Published: December 2024

The Nancy Grace Roman Space Telescope, set to launch in 2026, will bring unprecedented precision to measurements of weak gravitational lensing. Because weak lensing is an inherently small signal, it is imperative to minimize systematic errors in measurements as completely as possible; this will ensure that the lensing measurements can be used to their full potential when extracting cosmological information. In this paper, we use laboratory tests of the Roman detectors, simulations of the Roman High Latitude Survey observations, and the proposed Roman image combination pipeline to investigate the magnitude of detector read noise biasing on weak lensing measurements from Roman. First, we combine lab-measured detector noise fields with simulated observations and propagate these images through the Roman image combination pipeline, Imcom. We characterize the specific signatures of the noise fields in the resultant images and find that noise contributes to the combined images most strongly at scales relevant to physical characteristics of the detector including PSF shape, chip boundaries, and roll angles. We then measure shapes of simulated stars and galaxies and determine the magnitude of noise-induced shear bias on these measurements. We find that star shape correlations satisfy the system noise requirements as defined by the Roman Science Requirements Document. However, for galaxies fainter than m
AB ≃ 24, correction for noise correlations will be needed in order to ensure confidence in shape measurements in any observation band.
Enhancing Artillery System Analysis through Innovative Neural Networks: A Comparative Study of Kolmogorov–Arnold Networks in Fourier Operators
Authors: Tao Liu , Linfang Qian , Chen Liang
Published: December 2024

Many problems in artillery systems can be described using partial differential equations (PDEs), and engineers need to repeatedly adjust the design object to meet the requirements of the design phase. Therefore, an efficient PDEs solver is needed during the design phase. PDEs solvers based on deep learning, especially neural operators, can meet this requirement. However, neural operators use multi-layer perceptrons (MLP) to project data features onto the output dimension, and MLP lack interpretability, often face overfitting and gradient vanishing, and lack scalability. Kolmogorov–Arnold Networks (KAN) has recently been introduced and is considered a potential alternative to MLP. Based on this, KAN are used to construct Fourier Kolmogorov–Arnold Neural Operators (FKANO) for solving forward and inverse problems in artillery engineering. Especially in the three tasks of approximation, partial differential equation solving, and building surrogate models, the proposed FKANO and FNO were compared. It was found that although robustness during the training process is lacking in FKANO, performance comparable to or even surpassing that of FNO can still be achieved. The proposed new neural network is believed to have the potential to advance the development of artillery engineering analysis.
Simulation and optimization of a replenishment device for chainless ammunition feeding system
Authors: Guo Gaofeng , Li Zhong , Hou Yong , Yang Dewu , Cui Haohao , Tan Hui
Published: December 2024

In order to improve the efficiency of rapid replenishment of chainless ammunition feeding system, the dynamics simulation analysis of the movement relationship between the driving sprocket and the shell and the handover relationship between the toggle wheel and the shell in the replenishment device is carried out for the replenishment device of chainless ammunition feeding system as an object. Firstly, based on multi-body dynamics theory and contact collision theory, the dynamics model of the reloading device is established by using multi-body dynamics analysis software RecurDyn, and the simulation and optimization are carried out on the tooth profile shape of the sprocket wheel and the movement path of the shell in the reloading device; Secondly, using the multi-objective optimization method, the key parts of the reloading device were strength-checked and parameter-optimized using the finite element analysis software Workbench. The simulation and optimization results show that the change rate of the movement speed of the shell is 5.01%, and the change rate of the handover speed between the toggle wheels is 6.46%, and the movement of the shell is relatively smooth, which can meet the engineering requirements; The correctness of the model and the feasibility of the optimization are verified, and the key parts of the recharge device achieve a weight reduction of 59.23% after the optimization, which provides a certain reference for the subsequent optimization of the recharge device structure.
Investigation of a vector-controlled dual 5-phase motor driving system in artillery automatic loading applications
Authors: Zhu Jianlong , Tong Minghao , Wang Zhe , Chen Longmiao , Xu Zhiyuan
Published: December 2024

In order to improve the safety, reliability and fault-tolerant ability of the drive system in artillery automatic loading applications, the control method of a direct-motor-drive rotary manipulator is presented based on a dual 5-phase flux-switching permanent-magnet machine. The mathematical model is established according to the circuit topology firstly. Then, the dual 5-phase vector control strategy under normal condition and active-fault-tolerant condition is adopted. Simulation results show that the motor can effectively accomplish the drive task under normal or fault-tolerant condition. It is verified that the dual 5-phase shift 9° flux-switching permanent-magnet machine has strong adaptability and fault tolerant ability in the high-load and low-speed scenarios represented by the artillery automatic loading system.
A framework for multi-UAV task allocation and path planning in complex urban environments
Authors: Hu Shengrong , Wang Qiang , Li Yixian , Wang Fei
Published: December 2024

The complexity of urban combat environments, the coupling of task allocation and path planning, and the existence of dynamic targets significantly increased the complexity of coordinated UAV swarm attack tasks. In this work, we proposed a multi-UAV task allocation and path planning framework inspired by the collaborative hunting behaviour of wolf packs. This framework was based on a multi-target k-winner-take-all (k-WTA) algorithm and an improved grey wolf optimization (GWO) algorithm. Firstly, for the multi-task allocation problem in unknown environments, a multi-objective k-WTA algorithm was used for task allocation based on the competition mechanism, which realized fast task allocation in dynamic environments. Then, the advantages of GWO and genetic algorithm (GA) were combined through GA-WPO to overcome the random initialization problem of GWO by using GA as an initialization generator. A path planner based on GA-WPO was proposed to enable multi-UAVs to reach the target point safely in complex urban environments. Finally, the proposed path planner was used for multi-UAV path planning, and the effectiveness of the method was verified by a set of simulation experiments, which showed that the method better solved the coupling problem of path planning and task assignment for UAV swarm coordinated attack tasks.