bluuebunny/crossref_metadata_2025 huggingface dataset:
Making droplets from highly viscous liquids by pushing a wire through a tube
Authors: Sun Yueming , Ma Jianxing , Peng Fei , Kornev Konstantin G.
Published: March 2022

Drop-on-demand (DOD) printing is a versatile manufacturing tool, which has been widely used in applications ranging from graphic products to manufacturing of ceramics, even for cell engineering. However, the existing DOD methods cannot be applied for highly viscous materials: the printing technologies are typically limited to the inks with the water level viscosity and fall short to eject jets from thick fluids and break them into droplets. To address this challenge, a new wire-in-a-tube technology for drop generation has been developed replacing the nozzle generator with a wire-in-a-tube drop generator. We successfully formed droplets on demand from highly viscous (∼10 Pa s) liquids and studied the mechanisms of drop formation in the wire-in-a-tube drop generators. These mechanisms couple unique fluid mechanics, capillarity, and wetting phenomena providing a new platform that can be used in different microfluidic applications.
Intrinsic viscuit probability distribution functions for transport coefficients of liquids and solids
Authors: Heyes D. M. , Dini D.
Published: March 2022

A reformulation of the Green–Kubo expressions for the transport coefficients of liquids in terms of a probability distribution function (PDF) of short trajectory contributions, which were named “viscuits,” has been explored in a number of recent publications. The viscuit PDF, P, is asymmetric on the two sides of the distribution. It is shown here using equilibrium 3D and 2D molecular dynamics simulations that the viscuit PDF of a range of simple molecular single component and mixture liquid and solid systems can be expressed in terms of the same intrinsic PDF (P0), which is derived from P with the viscuit normalized by the standard deviation separately on each side of the distribution. P0 is symmetric between the two sides and can be represented for not very small viscuit values by the same gamma distribution formulated in terms of a single disposable parameter. P0 tends to an exponential in the large viscuit wings. Scattergrams of the viscuits and their associated single trajectory correlation functions are shown to distinguish effectively between liquids, solids, and glassy systems. The so-called viscuit square root method for obtaining the transport coefficients is shown to be a useful probe of small and statistically zero self-diffusion coefficients of molecules in the liquid and solid states, respectively. The results of this work suggest that the transport coefficients have a common underlying physical origin, reflecting at a coarse-grained level the traversal statistics of the system through its high-dimensioned potential energy landscape.
Spin-squeezed states for metrology
Authors: Sinatra Alice
Published: March 2022

Spin-squeezing is a well-established “quantum technology,” where well-designed correlations in an ensemble of two-level systems reduce the statistical uncertainty of spectroscopic experiments. This paper reviews some important advances in the field, with emphasis on the author's contributions concerning, in particular, the fundamental limits imposed by decoherence. Building on the material presented in the first part, new ideas and some promising developments are outlined in the last section.
Ytterbium oxide electron injection interface in organic light-emitting diode
Authors: Man Jia-Xiu , Hu Jun-Tao , Wang Deng-Ke , He Shou-Jie , Lu Zheng-Hong
Published: March 2022

The ytterbium oxide (Yb3+) is found to have an extremely low work function of 2.42 eV, which is even lower than that of its metallic form Yb0 (2.64 eV). The stability of oxides makes Yb3+ an ideal electron injection material for both top-emitting and bottom-emitting organic light-emitting diodes (TOLED and BOLED). The device test data indeed show that at 1000 nit luminance, the TOLED has a 94 cd/A current efficiency and 70 lm/W power efficiency, and BOLED has a 76 cd/A and 60 lm/W efficiency, respectively. X-ray and ultraviolet photoemission spectroscopical studies indicate that the Fermi level of the metal oxide is pinned to the lowest unoccupied molecular orbital of the electron transport layer, leading to the formation of a cathode interface with an ultra-low electron injection barrier.
Concurrently enhanced mechanical properties and capacitive performance in all-organic dielectric polymer blend via phase separation
Authors: Zhou Ting , Zhou Le , Liu Yi-Xuan , Lu Jing-Tong , He Shan , Li Wei , Li Geng , Yao Fang-Zhou , Shen Yang , Wang Ke
Published: March 2022

Phase separation of polymer blends has attracted much interest in designing high-performance materials with specific mechanical and dielectric properties. To this end, three types of poly(methacrylic ester)s, including poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), and poly(isobutyl methacrylate) [P(iBMA)], have been incorporated in the poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] matrix, respectively. As exemplified in P(VDF-HFP)/P(iBMA) blended films, a conspicuous phase separation is experimentally observed and the blended film presents an enhanced Young's modulus and a one-fold increment in the elongation over the pristine P(VDF-HFP). The excellent plasticity is benefited from the interfacial regions between the two phases, which could effectively pin the cracks and retard the slippage under deformation. Simultaneously, an ultra-high Weibull breakdown strength (∼774 MV/m) is obtained in the blends, benefiting from the improved Young's modulus and excellent plasticity. The blends are endowed with an excellent energy storage density (∼21 J/cm3 at 830 MV/m), along with an impressive cycling stability. In contrary, P(VDF-HFP)/PMMA and P(VDF-HFP)/PBMA blended films sacrifice the plasticity due to the scarcity of phase separation; therefore, even though Young's moduli have been improved, there is no remarkable improvement for breakdown strengths and energy storage performances. The experimental results are augmented by molecular dynamics simulations. This contribution provides a facile approach to develop high-performance polymer dielectric materials through a phase separation design and emphasize the importance of plasticity for breakdown strength.
AutoSolvate: A toolkit for automating quantum chemistry design and discovery of solvated molecules
Authors: Hruska Eugen , Gale Ariel , Huang Xiao , Liu Fang
Published: March 2022

The availability of large, high-quality datasets is crucial for artificial intelligence design and discovery in chemistry. Despite the essential roles of solvents in chemistry, the rapid computational dataset generation of solution-phase molecular properties at the quantum mechanical level of theory was previously hampered by the complicated simulation procedure. Software toolkits that can automate the procedure to set up high-throughput explicit-solvent quantum chemistry (QC) calculations for arbitrary solutes and solvents in an open-source framework are still lacking. We developed AutoSolvate, an open-source toolkit, to streamline the workflow for QC calculation of explicitly solvated molecules. It automates the solvated-structure generation, force field fitting, configuration sampling, and the final extraction of microsolvated cluster structures that QC packages can readily use to predict molecular properties of interest. AutoSolvate is available through both a command line interface and a graphical user interface, making it accessible to the broader scientific community. To improve the quality of the initial structures generated by AutoSolvate, we investigated the dependence of solute–solvent closeness on solute/solvent identities and trained a machine learning model to predict the closeness and guide initial structure generation. Finally, we tested the capability of AutoSolvate for rapid dataset curation by calculating the outer-sphere reorganization energy of a large dataset of 166 redox couples, which demonstrated the promise of the AutoSolvate package for chemical discovery efforts.
The spall and anomalous inelastic response of Galfenol to shock loading
Authors: Turnage S. A. , Ligda J. P. , Cazamias J. U. , Williams C. L.
Published: March 2022

Plate impact experiments were performed to probe the dynamic response of Galfenol, specifically the Hugoniot elastic limit (HEL), spall strength, and failure characteristics. Galfenol exhibits low HEL and high spall strength as compared to α-Fe, possibly owing to the large grain size and strong texture. A cusp is observed on the velocity–time profiles that exhibits pronounced stress and strain rate dependence. The nature of this cusp is not well understood, but it may possibly be related to the ferromagnetic-to-paramagnetic second order phase transformation induced by shock waves. Shock-recovered specimens exhibit brittle intergranular fracture under compressive loading with cracks initiating and growing along the shock direction. It is expected, though not confirmed, that these cracks grow along grain boundaries owing to embrittlement by Ga segregation at the boundaries.
Rapid cooling performance of zirconium rods quenched in natural seawater
Authors: Ebrahim Shikha A. , Pradeep Emil
Published: March 2022

The viability of using natural seawater as an effective working coolant to ensure safe and efficient cooling mechanism is a significant study in the Arabian Gulf region. This study investigates transient pool boiling characteristics of natural seawater collected from different locations in the Arabian Gulf coast of Kuwait, compared to the baseline case of distilled water. Seawater samples are collected from prime locations (Shuwaikh, Al Zour, and Doha ports), which are highly capable of accommodating upcoming power plants and nuclear reactors. Extremely heated vertical zirconium rods are quenched in saturated pools at atmospheric pressure. A detailed study of the seawater samples is carried out through semi-quantitative calculation (SQX) results to evaluate the elemental composition, and water quality comparisons are made based on pH, total dissolved solids, and conductivity. The cooling performance is monitored by plotting the quenching and cooling rate curves, and evaluated based on the minimum film boiling temperature (Tmin) and maximum cooling rate. The results demonstrate an excellent improvement in Tmin and maximum cooling rate by employing natural seawater collected from Al Zour, which is located in the southern part of Kuwait. A minimum of 10% increase in Tmin is depicted by Al Zour seawater. The enhancement is attributed to the salt deposition activity caused by sudden evaporation of seawater on the surface. The salt deposits destabilize the vapor film to promote early vapor film breakage and act as an additional nucleation site to initiate early nucleate boiling, leading to an efficient cooling performance. Seawater collected from Shuwaikh port demonstrates a negative influence on the effective change in Tmin. A detailed examination is carried out on the surface of zirconium samples with the help of wavelength dispersive x-ray fluorescence analysis and SQX analysis, to identify and evaluate the prime elements responsible for the enhanced cooling performance. This study proves that even though the seawater is collected along the same coast, its characteristics differ when utilizing it in cooling systems.
Accurate characterization of surface recombination velocities of silicon wafers with differential nonlinear photocarrier radiometry
Authors: Lei Xiaoke , Li Bincheng , Sun Qiming , Wang Jing , Wang Yafei
Published: March 2022

The surface recombination velocity (SRV), which reflects the fundamental characteristics of surface defects of semiconductor wafers, is an important parameter in evaluating the quality of surface passivation and electrical performance of surface devices. In conventional photocarrier radiometry (PCR) used for characterizing the electronic transport properties of electronically thick silicon wafers, the rear SRV usually cannot be determined directly due to the relatively low sensitivity of PCR signal to the rear SRV. On the other hand, the determination of front SRV is also very sensitive to the experimental measurement error, especially the measurement error of instrumental frequency response, which is not always easy to be accurately measured in the experiment. In this paper, the front and rear SRVs of silicon wafers are extracted simultaneously with high accuracy by a differential PCR via multi-parameter fitting of the experimental frequency dependences of amplitude ratio and phase difference of PCR signals obtained from the regular measurements and measurements with wafers being flipped respectively to a corresponding differential nonlinear PCR model. The comparison between the front and rear SRVs determined by the conventional and differential PCRs indicates that the differential PCR is highly accurate for the simultaneous determination of the front and rear SRVs of silicon wafers.
Red InGaN micro-light-emitting diodes (>620 nm) with a peak external quantum efficiency of 4.5% using an epitaxial tunnel junction contact
Authors: Li Panpan , Li Hongjian , Zhang Haojun , Yang Yunxuan , Wong Matthew S. , Lynsky Cheyenne , Iza Mike , Gordon Michael J. , Speck James S. , Nakamura Shuji , DenBaars Steven P.
Published: March 2022

We present efficient red InGaN 60 × 60 μm2 micro-light-emitting diodes (μLEDs) with an epitaxial tunnel junction (TJ) contact. The TJ was grown by metal-organic chemical vapor deposition using selective area growth. The red TJ μLEDs show a uniform electroluminescence. At a low current density of 1 A/cm2, the emission peak wavelength is 623 nm with a full-width half maximum of 47 nm. The peak external quantum efficiency (EQE) measured in an integrating sphere is as high as 4.5%. These results suggest a significant progress in exploring high efficiency InGaN red μLEDs using TJ technology.
Classification of process conditions in martensitic stainless steel: A machine learning approach on magnetic Barkhausen emission signals
Authors: Mohan Manju , Ramya M. M.
Published: March 2022

Sorting of materials at different stages of manufacturing processes is very important to ensure the final product quality. In this paper, the machine learning algorithms are used on the magnetic Barkhausen emission (MBE) signals for the classification of martensitic stainless-steel specimens, which are subjected to different heat treatments. The variation in MBE parameters, such as root mean square, peak height, peak position, and full width at half maximum, was found to be marginal for normalized and quenching and partitioned specimens even though their x-ray diffraction analysis showed distinct microstructural conditions. The conventional MBE parameters are used to train the machine learning models. The performance of decision tree and ensemble learning techniques, such as Bagging, Random Subspace, AdaBoost, RUSBoost, Total Boost, and LP Boost classifiers, is compared and found that the AdaBoost classifier provides the maximum accuracy of 98% in the classification of complex materials. The results showed that the machine learning approach using a limited number of features is sufficiently sensitive toward the classification of specimens that are otherwise indistinguishable in their conventional MBE response.
Mechanical cloak via data-driven aperiodic metamaterial design
Authors: Wang Liwei , Boddapati Jagannadh , Liu Ke , Zhu Ping , Daraio Chiara , Chen Wei
Published: March 2022

Significance

An invisibility cloak to conceal objects from an outside observer has long been a subject of interest in metamaterial design. While cloaks have been manufactured for optical, thermal, and electric fields, limited progress has been made for mechanical cloaks. Most existing designs rely on mapping-based methods, which have so far been limited to special base cells and a narrow selection of voids with simple shapes. In this study, we develop a fundamentally different approach by exploiting data-driven designs to offer timely, customized solutions to mechanical cloaking that were previously difficult to obtain. Through simulations and experimental validations, we show that excellent cloaking performance can be achieved for various boundary conditions, shapes of voids, base cells, and even multiple voids.
Precise stellarator quasi-symmetry can be achieved with electromagnetic coils
Authors: Wechsung Florian , Landreman Matt , Giuliani Andrew , Cerfon Antoine , Stadler Georg
Published: March 2022

Magnetic fields with quasi-symmetry are known to provide good confinement of charged particles and plasmas, but the extent to which quasi-symmetry can be achieved in practice has remained an open question. Recent work [M. Landreman and E. Paul,
Phys. Rev. Lett.
128, 035001, 2022] reports the discovery of toroidal magnetic fields that are quasi-symmetric to orders-of-magnitude higher precision than previously known fields. We show that these fields can be accurately produced using electromagnetic coils of only moderate engineering complexity, that is, coils that have low curvature and that are sufficiently separated from each other. Our results demonstrate that these new quasi-symmetric fields are relevant for applications requiring the confinement of energetic charged particles for long time scales, such as nuclear fusion. The coils’ length plays an important role for how well the quasi-symmetric fields can be approximated. For the longest coil set considered and a mean field strength of 1 T, the departure from quasi-symmetry is of the order of Earth’s magnetic field. Additionally, we find that magnetic surfaces extend far outside the plasma boundary used by Landreman and Paul, providing confinement far from the core. Simulations confirm that the magnetic fields generated by the new coils confine particles with high kinetic energy substantially longer than previously known coil configurations. In particular, when scaled to a reactor, the best found configuration loses only 0.04% of energetic particles born at midradius when following guiding center trajectories for 200 ms.
Adapting to their new home: Eosinophils remodel the gut architecture
Authors: Arnold Isabelle Catherine
Published: March 2022

In this issue of JEM, Diny et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20210970) identify the aryl hydrocarbon receptor (AHR) as a key orchestrator of eosinophil tissue adaptation in the small intestine, controlling their lifespan, degranulation, and tissue-remodeling activities.
Study of correlations between seismic data and Virgo’s gravitational-wave detector data
Authors: Figura Przemysław , Bulik Tomasz , Harms Jan , Calloni Enrico , Errico Luciano , De Rosa Rosario , Gennai Alberto
Published: March 2022

It is expected that noise produced by terrestrial gravity fluctuations will start to limit the sensitivity of the ground-based, gravitational-wave detector Virgo in coming observation runs. A system is under preparation at Virgo to cancel this noise, also known as Newtonian noise. This Newtonian noise cancelation system requires the deployment of seismometer arrays inside the Virgo buildings. Crucial for the design of such a system is a detailed understanding of correlations between ground vibrations and Virgo’s gravitational waves detector data. In this article, we present first analyses of such correlations observed with a tiltmeter. We find that revealed correlations are stronger than predicted by possible pure gravitational coupling, which is pointing towards additional coupling mechanisms. These findings might impact the design of the Newtonian noise cancelation system if the additional couplings cannot be mitigated.
Extreme ℓ-boson stars
Authors: Alcubierre Miguel , Barranco Juan , Bernal Argelia , Degollado Juan Carlos , Diez-Tejedor Alberto , Jaramillo Víctor , Megevand Miguel , Núñez Darío , Sarbach Olivier
Published: March 2022

A new class of complex scalar field objects, which generalize the well known boson stars, was recently found as solutions to the Einstein–Klein–Gordon system. The generalization consists in incorporating some of the effects of angular momentum, while still maintaining the spacetime’s spherical symmetry. These new solutions depend on an (integer) angular parameter ℓ, and hence were named ℓ-boson stars. Like the standard ℓ = 0 boson stars these configurations admit a stable branch in the solution space; however, contrary to them they have a morphology that presents a shell-like structure with a ‘hole’ in the internal region. In this article we perform a thorough exploration of the parameter space, concentrating particularly on the extreme cases with large values of ℓ. We show that the shells grow in size with the angular parameter, doing so linearly for large values, with the size growing faster than the thickness. Their mass also increases with ℓ, but in such a way that their compactness, while also growing monotonically, converges to a finite value corresponding to about one half of the Buchdahl limit for stable configurations. Furthermore, we show that ℓ-boson stars can be highly anisotropic, with the radial pressure diminishing relative to the tangential pressure for large ℓ, reducing asymptotically to zero, and with the maximum density also approaching zero. We show that these properties can be understood by analyzing the asymptotic limit ℓ → ∞ of the field equations and their solutions. We also analyze the existence and characteristics of both timelike and null circular orbits, especially for very compact solutions.
The momentum constraint equation in parameterised post-Newtonian cosmology
Authors: Anton Theodore , Clifton Timothy
Published: March 2022

We derive a theory-independent version of the momentum constraint equation for use in cosmology, as a part of the parameterised post-Newtonian cosmology framework. Our equations are constructed by adapting the corresponding quantities from formalisms constructed for testing and constraining gravity in isolated astrophysical systems, thereby extending the domain of applicability of these approaches up to cosmological scales. Our parameterised equations include both scalar and divergenceless-vector gravitational potentials, and can be applied to both conservative and non-conservative theories of gravity. They can also be used to describe the gravitational fields of both non-linear structures and super-horizon perturbations. We apply the parameterised equations we propose to quintessence models of dark energy, as well as scalar-tensor and vector-tensor theories of gravity. We find them to work well in each case. Our equations are highly compact, and are intended to be useful for constraining gravity in a theory-independent fashion in cosmology.
Electronic and optical properties of Janus black arsenic-phosphorus AsP quantum dots under magnetic field
Authors: Yan Xuefei , Ke Qingqing , Cai Yongqing
Published: March 2022

By utilizing the tight-binding method, the electronic spectrum and states distribution of square Janus monolayer black arsenic phosphorus (b-AsP) quantum dots (QDs) in the presence of a perpendicular magnetic field are explored. Strong in-gap states of b-AsP QDs, whose probability densities are distributed on the armchair boundary (armchair edge states) appear in the energy gap of host perfect two-dimensional b-AsP. The corresponding energy levels of the armchair edge states can degenerate to the Landu energy levels upon applying a perpendicular magnetic field. When an in-plane polarized light is introduced, due to the presence of armchair edge states, the edge-to-edge transitions are mainly induced from the armchair edge (hole) states to zigzag edge (electron) states. The optical absorption undergoes blue shift as a function of the magnetic field. Our work suggests tunable optical properties via modulating the armchair edge states of a b-AsP QD and provides a theoretical basis for the design of b-AsP-based optoelectronic devices.
Twisted graphene stabilized by organic linkers pillaring
Authors: Liu Chengyuan , Li Wenlian , Xue Lin , Hao Yuying
Published: March 2022

Twisted graphene, including magic angle graphene, has attracted extensive attentions for its novel properties recently. However, twisted graphene is intrinsically unstable and this will obstruct their application in practice, especially for twisted nano graphene. The twist angles between adjacent layers will change spontaneously. This relaxation process will be accelerated under heat and strain. To solve this problem, we propose a strategy of pillaring twisted graphene by organic linkers in theory. The necessity and feasibility of this strategy is proved by numerical calculation.
Evaluation of cerebral cortex viscoelastic property estimation with nonlinear inversion magnetic resonance elastography
Authors: Hiscox Lucy V , McGarry Matthew D J , Johnson Curtis L
Published: March 2022

Objective. Magnetic resonance elastography (MRE) of the brain has shown promise as a sensitive neuroimaging biomarker for neurodegenerative disorders; however, the accuracy of performing MRE of the cerebral cortex warrants investigation due to the unique challenges of studying thinner and more complex geometries. Approach. A series of realistic, whole-brain simulation experiments are performed to examine the accuracy of MRE to measure the viscoelasticity (shear stiffness, μ, and damping ratio, ξ) of cortical structures predominantly effected in aging and neurodegeneration. Variations to MRE spatial resolution and the regularization of a nonlinear inversion (NLI) approach are examined. Main results. Higher-resolution MRE displacement data (1.25 mm isotropic resolution) and NLI with a low soft prior regularization weighting provided minimal measurement error compared to other studied protocols. With the optimized protocol, an average error in μ and ξ was 3% and 11%, respectively, when compared with the known ground truth. Mid-line structures, as opposed to those on the cortical surface, generally display greater error. Varying model boundary conditions and reducing the thickness of the cortex by up to 0.67 mm (which is a realistic portrayal of neurodegenerative pathology) results in no loss in reconstruction accuracy. Significance. These experiments establish quantitative guidelines for the accuracy expected of in vivo MRE of the cortex, with the proposed method providing valid MRE measures for future investigations into cortical viscoelasticity and relationships with health, cognition, and behavior.
Cone-beam breast CT using an offset detector: effect of detector offset and image reconstruction algorithm
Authors: Tseng Hsin Wu , Karellas Andrew , Vedantham Srinivasan
Published: March 2022

Objective. A dedicated cone-beam breast computed tomography (BCT) using a high-resolution, low-noise detector operating in offset-detector geometry has been developed. This study investigates the effects of varying detector offsets and image reconstruction algorithms to determine the appropriate combination of detector offset and reconstruction algorithm. Approach. Projection datasets (300 projections in 360°) of 30 breasts containing calcified lesions that were acquired using a prototype cone-beam BCT system comprising a 40 × 30 cm flat-panel detector with 1024 × 768 detector pixels were reconstructed using Feldkamp–Davis–Kress (FDK) algorithm and served as the reference. The projection datasets were retrospectively truncated to emulate cone-beam datasets with sinograms of 768

×

768 and 640

×

768 detector pixels, corresponding to 5 cm and 7.5 cm lateral offsets, respectively. These datasets were reconstructed using the FDK algorithm with appropriate weights and an ASD-POCS-based Fast, total variation-Regularized, Iterative, Statistical reconstruction Technique (FRIST), resulting in a total of 4 offset-detector reconstructions (2 detector offsets × 2 reconstruction methods). Signal difference-to-noise ratio (SDNR), variance, and full-width at half-maximum (FWHM) of calcifications in two orthogonal directions were determined from all reconstructions. All quantitative measurements were performed on images in units of linear attenuation coefficient (1/cm). Results. The FWHM of calcifications did not differ (P > 0.262) among reconstruction algorithms and detector formats, implying comparable spatial resolution. For a chosen detector offset, the FRIST algorithm outperformed FDK in terms of variance and SDNR (P < 0.0001). For a given reconstruction method, the 5 cm offset provided better results. Significance. This study indicates the feasibility of using the compressed sensing-based, FRIST algorithm to reconstruct sinograms from offset-detectors. Among the reconstruction methods and detector offsets studied, FRIST reconstructions corresponding to a 30 cm × 30 cm with 5 cm lateral offset, achieved the best performance. A clinical prototype using such an offset geometry has been developed and installed for clinical trials.
A comprehensive physics based surface potential and drain current model for SiGe channel dual programmable FETs
Authors: Pandey Priyanka , Kaur Harsupreet
Published: March 2022

In the present work, a comprehensive analytical model for surface potential and drain current has been developed for double gate silicon-germanium channel dual programmable FETs (SiGe-DP-FET) which is capable to conduct both in n- as well as p-modes. The developed model accurately predicts the impact of mole fraction (m) variation in Si(1 − m)Ge
m
channel on various device characteristics such as energy band, surface potential, electric field, drain current, and transconductance. While deriving the surface potential expression, the active SiGe channel is bifurcated in three regions such that regions I and III denote the two gated regions while region II denotes the ungated region. Further, in order to compute the expression for surface potential, 2D Poisson’s equation has been solved in gated regions while linear approximation has been applied in ungated region and subsequently, the drain current expression has been obtained by integrating the band-to-band generation rate of charge carriers across the source side Schottky junctions. Moreover, in order to validate the proposed model, the analytical results are compared and verified with 2D TCAD ATLAS simulated results and it has been observed that the results obtained using proposed model match well with the simulated results.
Hot carrier spatio-temporal inhomogeneities in ultrafast nanophotonics
Authors: Schirato Andrea , Crotti Giulia , Proietti Zaccaria Remo , Alabastri Alessandro , Della Valle Giuseppe
Published: March 2022

Light-induced hot carriers in nanostructures and their corresponding optical nonlinearity have been extensively examined during the last decades. However, nonlinear optical effects dictated by the spatio-temporal evolution of out-of-equilibrium electrons at the nanoscale represent a much more recent research focus. Here we theoretically discuss the role of spatial inhomogeneities that energetic electrons feature across individual nanoantennas in metasurface configuration upon illumination with femtosecond laser pulses. As exemplary cases, we consider two-dimensional geometries of gold meta-atoms having either a high aspect ratio or a tapered cross-section and model their ultrafast optical response. A comparison with numerical results obtained either neglecting or accounting for spatial effects indicates that deep sub-wavelength spatio-temporal transients of carriers may have a significant impact on the dynamics of the all-optically modulated signal, with major quantitative corrections up to predicted changes in sign. Our results present hot-electron local inhomogeneities as an emerging subject with potentially relevant applications in various ultrafast nanophotonic configurations.
Electrical conduction mechanism and dielectric relaxation of bulk disodium phthalocyanine
Authors: Alosabi A Q , Al-Muntaser A A , El-Nahass M M , Oraby A H
Published: March 2022

AC conductivity and dielectric characteristics of disodium phthalocyanine (Na2Pc) in a pellet form were investigated in a frequency range from 45 Hz to 3.12 MHz and a temperature range from 303 to 423 K. The charge carrier transport mechanism was determined according to the correlated barrier hopping model (CBH). Also, the electrical parameters were estimated in light of this model. The thermal activation energy of AC conductivity decreases with increasing frequency. The behavior dependence of dielectric loss and dielectric constant on temperature and frequency was discussed. The behavior of dielectric loss was explained based on the Giuntini model. The maximum value of barrier height,

W

M

,

was obtained to equal

0.38

eV
.

The results showed that the type of relaxation mechanism is a non-Debye one. The activation energy is calculated for dielectric relaxation to be

0.36

eV
.
A New Multichannel Parallel Real-time FFT Algorithm for a Solar Radio Observation System Based on FPGA
Authors: Zhang Yuan Y. , Zhang Lei , Shang Zi Q. , Su Yan R. , Wu Zhao , Yan Fa B.
Published: March 2022

The real-time fast Fourier transform (FFT) is the essential algorithm for signal processing in a solar radio receiver. However, field-programmable gate array (FPGA) computation resources have become the limitation of real-time processing of signals with increasing time and spectral resolutions. It is necessary to design a real-time parallel FFT algorithm with reduced resource occupation in the development of future receiving systems. In this paper, we developed a multichannel parallel FFT algorithm named the multichannel parallel real-time fast Fourier transform (MPR-FFT), which can greatly reduce FPGA resource occupation while increasing the real-time processing speed. In this algorithm, the 4L simultaneous N-point FFTs are first converted into L simultaneous 4N-point FFTs. Fusion processing is then performed to obtain the 4 ∗ L ∗ N-point spectrum. This method has been used in developing a solar radio spectrometer, which works in the frequency range of 0.5–15 GHz in the Chashan Observatory. In this spectrometer, 16 channel MPR-FFT with 8k-point data is realized in a Xilinx UltraScale KU115 FPGA. The MPR-FFT algorithm reduced the computational resources to a large extent compared to the Cooley-Tukey-based parallel FFT method; for instance, the Look-Up-Table, Look-Up-Table RAM, Flip-Flop, and Digital Signal Process slices were reduced by 37%, 50%, 17%, and 2.48%, respectively. Although the MPR-FFT consumes 14 block RAM resources more than the Cooley-Tukey-based parallel FFT, the MPR-FFT algorithm presents an overall reduction in resource usage.
The use of interpolation methods for modelling multifactor processes based on an experiment planning matrix
Authors: Konopatskiy E V , Seleznev I V , Bezditnyi A A
Published: March 2022

This article is dedicated to the development of experimental data processing tools based on the geometric theory of multidimensional interpolation. At the same time, a scientific problem was solved, which is dedicated to the analytical determination of models of multifactor processes while maintaining the existing approach to experiment planning This makes it possible not only to use interpolation methods for the mathematical description of new experiments, but also to use the experimental data obtained earlier to improve their mathematical interpretation. The paper provides two examples that confirm the effectiveness of the proposed approach to constructing models of multivariate processes using multivariate interpolation methods. The first of the above examples contains two geometric models of the stress-strain state of metal polyhedral bent struts, which are presented in the form of ruled response hypersurfaces passing through 8 predetermined points in the 4-dimensional space. The second one is dedicated to the construction of a 2-factor process process using a 2- parameter parabolic geometric interpolant with subsequent optimization by methods of mathematical analysis of a function of two variables. As a result, the optimization of the aerated concrete manufacturing process was carried out to achieve the maximum values of the ultimate strength in compression after heat and moisture treatment.
Analysis of modern measuring instruments for research diagnostic systems of print media equipment
Authors: Shmelev F Yu , Orlova E Yu , Sultanova Yu M , Varepo L G
Published: March 2022

The quality of printing products substantially depends on the accuracy of the individual mechanisms of the printing equipment. Since technological processes usually last in a period of a second, conventional measuring instruments turn out to be too inertial; therefore, to detect deviations of the given parameters (loads, locations, accelerations) from the calculated values, various sensors are used. The work is devoted to the selection of diagnostic tools for typical measurements used in print media equipment on printing equipment. Possibilities of parallel measurements and mutual analysis of signals of the designed diagnostic systems for research of parameters of the equipment of the print media industry are considered.
Discrete-event simulation of load distribution between server stations
Authors: Denisov O V
Published: March 2022

The simulation model of the computational load balancing in a server complex using a balancing server is proposed. The server load balancing model was developed using MATLAB/Simulink/SimEvents/Stateflow tools. The SimEvents based model makes it possible to simulate the server complex as a queuing system and to take into account the sporadic occurrence of requests. The Stateflow based event-driven model simulates the system with a variable time delay in data transmission channels and simulates state transitions for servers. This discrete-event simulation model allows evaluating the possibility of rational use of computational resources and reducing the time of service. In addition, the model allows to investigate the effectiveness of load balancing systems at the stage of their development.
Factorial research and the recognition problem solution using the example of obstructive sleep apnea syndrome
Authors: Goltyapin V V
Published: March 2022

The article is devoted to the problem of identifying factors directly or indirectly influencing the presence of obstructive sleep apnea syndrome in patients (OSAS) and solving the problem of pattern recognition in the factor space using the example OSAS. A factorial study was carried out for each group of indicators characterizing the condition of patients with OSAS, optimal factor structures were formed and the interpretation of the identified latent-integrative factors was carried out. It was implemented Bayes’ formula for calculating probabilities by OSAS groups in factor space. It is proposed formula for the transition from initial data to factors for finding the n-dimensional distribution density which is necessary for solving problems of recognition and based on the Bayesian criterion. There are given the proof of the transition formula and computational algorithms for the recognition problem.
Cylindrical shear waves in soil around underground pipelines
Authors: Khusanov B E , Rikhsieva B B
Published: March 2022

A method of numerical solution of one-dimensional problem of cylindrical shear wave propagation in an elastic and elastic-plastic soil is developed in the article using the finite difference method. The numerical results obtained are presented in the form of graphs. From the results obtained, the attenuation of the parameters (shear stress, shear strain, and angular velocity) of cylindrical wave propagation with distance in an elastic and elastic-plastic soil was determined. The attenuation of waves with distance is justified by the dissipation of strain energy on the expanding cylindrical soil layer. In the case of load exceeding the elastic limit, plastic strains occur in soil near the point of load application. The boundaries of elastic-plastic strain of soil are determined.
Electrodynamic long-stroke drive as an inertial compensator of low-frequency vibroactive forces
Authors: Burian Yu A , Sitnikov D V , Burian A A
Published: March 2022

The article discusses various possibilities of using an electrodynamic drive with an increased displacement of a movable permanent magnet as a low-frequency inertial compensator of vibroactive forces.The main attention is paid to the analysis of an active dynamic vibration damper (ADVD) when installing an electrodynamic compensator (EDC) on the base near vibration supports and when connecting the EDC moving mass with a vibroactive mass using a spring. It is shown that the considered ADVD is effective as a vibration isolator in the low-frequency range.
Development of antenna system for use in meteorological and climatic control complexes
Authors: Kudryashov M A , Belousov O A , Tetyukhin V I , Kiryupin M M , Belyaev V P , Nagornova I V , Bezzateeva E G
Published: March 2022

The synthesis of a cylindrical antenna array for ground-based mobile weather monitoring complexes, based on quadrifilar radiators, is considered. The basic mathematical expressions for determining the electrodynamic characteristics of both the radiator from the antenna array and the AA itself are presented. Various phenomenological models of these radiators are considered. The approach to the synthesis of phenomenological models of the radiator and antenna array as a whole is described. The results of such synthesis are given, and the main characteristics and values of DG, CG, SWR, RP for the given type of radiator and AA in the corresponding frequency range are obtained. Techniques for using phenomenological models for operational synthesis of electrodynamic structures such as cylindrical AA and quadrifilar radiator are developed and described in detail. The possibility of applying this approach to the synthesis of this type of structures for radar weather monitoring systems is shown.
Effectiveness analysing of modification of training data set for voice forgery detection system
Authors: Mikhaltsov V E , Semenova Z V , Stepanova E A
Published: March 2022

Paper presents data of the experiments with the advanced model of voice authentication. The main idea of the research is to prove or deny the hypotese that adding generated fake data to the training set of the background model help to increase the probability of detecting fake data of the target announcer. Processing the results of a series of experiments did not confirm the hypothesis.
Investigation of the operation of a microwave autogenerator with emitters of various designs
Authors: Vavilov I S , Yachmenev P S , Fedyanin V V , Zharikov K I , Stepen’ P V , Lukyanchik A I
Published: March 2022

This paper presents the results of experimental studies of 15 design versions of capacitive and induction type microwave antennas. As part of the work on the development of an accelerator ion thruster, 32 radiator designs were studied. The research was carried out in order to select the optimal design of a plasma-generating microwave antenna for installation in the discharge chamber of a prototype ion thruster. The volt-ampere characteristics (VAC) were obtained the microwave generator when working with each design of the radiator in a vacuum chamber. The VAC is obtained in the presence and absence of a high-frequency discharge.
Review of Nmij Studies Using The Primary pH Method
Authors: Maksimov I , Asakai T , Ohata M
Published: March 2022

In the field of pH measurements, the NMIJ, as designated metrology body, provides the traceability to international pH standards for a country, disseminate the certified buffer solutions for JCSS [1] and develops new measurements technologies. In this review we would like to present the last topic with the short description of some recent studies involving the Harned cell
Selection of a regression model for graduation of measuring instruments when it is necessary to estimate stability of the calibration curve
Authors: Zubkov P N , Nechaev N V
Published: March 2022

A method for choosing the best regression model for the cases when the measuring task is associated with the study of the stability of the metrological characteristics of the calibrated measuring instrument is described. A description of the experiment set up when using this method in the course of researching the metrological characteristics of measuring instruments for the numeric concentration of light air ions is given, and the research results obtained using this method are given.
Development of metrological support for color calibration of digital microscopy systems
Authors: Makhov D S , Samorodova O A , Muravskaya N P , Samorodov A V
Published: March 2022

The article is dedicated to the color reproducibility in images obtained on various digital microscopy systems (DMS). This problem can be solved by color calibration with a special slide. According to the previously formulated requirements, a slide prototype for DMS color calibration was developed and manufactured. Several color calibration algorithms were tested to choose the best one for minimizing the color difference. Color calibration algorithms were based on polynomials of different degrees with and without cross terms for CIE Lab color fields’ coordinates. This comparison was made with the color slide prototype and two DMSs based on Meiji MT4300 and Olympus BX41 microscopes. The comparison proved the polynomials with cross terms of 3rd and 4th degrees to be the best for DMSs based on Meiji and Olympus microscopes, respectively. The minimal color difference with respect to the true color fields’ coordinates was 0.75 ΔE* and 0.66 ΔE* for Meiji and Olympus, respectively. The results indicate the suitability of the slide prototype for DMS color calibration since it is possible to achieve a color difference below the visually distinguishable threshold of 2.2 ΔE*.
Spectral and dosimetric properties of multilayer structures of radiochromic absorbed dose reference materials
Authors: Tenishev V
Published: March 2022

The paper considers a method for extending ionizing radiation absorbed dose measurement range by multilayer technology of one-, two-, three- and four-layer radiochromic films. It shows that this technology expands the AD measurement range to the small dose region of 10-1000 Gy.
Key development stages of reference material for lactose monohydrate composition
Authors: Kasilyunas Anastasia V , Medvedevskikh Maria Yu , Krashenina Maria P , Sergeeva Anna S
Published: March 2022

The article mirrors key stages of development of reference material (RM) for the composition of lactose monohydrate with certified values of mass fraction of water and basic material. The RM could be used in the analytical chemistry and food industry, as well as at identification and assessment of nutritive products safety, int. al., infant food. The RM under development will be intended for metrological assurance of mass fraction of water and basic substance measuring instruments based on usage of thermogravimetric, titrimetric and chromatographic methods, certification of measurement procedures and control of measurement results of lactose monohydrate mass fraction accuracy, used as the host material, and in compositions of organic substances and materials or in measurements of water mass fraction in solid substances and materials, as well as for other kinds of metrological control. Determination of certified value of lactose monohydrate mass fraction in the RM was performed by reference method of iodometric titration and affirmed by mass balance method (one hundred minus the number of impurities) and by calculating-experimental method. The certified value of mass fraction of water was assigned by the Fischer’s method of volumetric titration and confirmed by the thermogravimetric method. Considerable attention was focused to the study of the separation process of sorbed and crystallisation water in a high-purity lactose monohydrate reagent. The results of measurements of the quantitative content of the types of water were considered when assessing the purity of the target substance by various methods. Unlike existing RM of similar composition, the traceability of the certified values of the RM being developed will be ensured to units of values reproduced respectively by the state primary (GET 173-2017) and secondary (GVET 176-1-2010) standards.