bluuebunny/crossref_metadata_2025 huggingface dataset:
An atomic view on the evolution of spall damage in solid–liquid mixed aluminum at high strain rates through stretching simulations
Authors: Wang Xin-Xin , Sun Zhi-Yuan , Zhao Fu-Qi , He An-Min , Zhou Ting-Ting , Zhou Hong-Qiang , Zhang Feng-Guo , Wang Pei
Published: November 2021

Using the classical molecular dynamic method, we investigated the evolution of spall damage through a series of stretching simulations for solid–liquid mixed aluminum at several initial temperatures. The results show that a turning point appears before void nucleation when the initial temperature is higher than 940 K in mixed Al at a strain rate of 3 × 108 s−1. The formation mechanism of the turning point is due to the local liquid phase nucleation. The growth of the local liquid phase gradually destroys the consecutive solid phases. The lower tensile strength of liquid Al than solid Al leads to the formation of the turning point. The voids tend to nucleate in the liquid phase in mixed Al at different initial temperatures except at 940 K. The time of void nucleation will be delayed due to the melting process before void nucleation in mixed Al. A nucleation and growth (NAG) model can describe the nucleation and growth of voids very well in mixed Al at 900, 920, 960, and 980 K. By adding the criterion of liquid phase proportion, the NAG model can also well describe the void volume fraction history of mixed Al at 940 K. We clarified the micro-mechanisms of spall damage evolution in mixed Al through tension simulation. The relevant results can provide a reference for future work on spall damage studies in solid–liquid mixed metals.
Radiative contribution to thermal grating decay
Authors: Maznev A. A. , Robertson S. G. , Short M. P. , Nelson K. A.
Published: November 2021

The decay of a spatially sinusoidal temperature perturbation (thermal grating) via thermal transport by both conduction and radiation is analyzed theoretically. The intrinsic non-radiative conduction is described by the heat diffusion equation while radiative transport is described by the radiation transport equation for a non-scattering absorbing medium. We solve the coupled equations analytically and obtain the thermal grating decay rate, which leads to an explicit expression for the radiative contribution to the effective thermal conductivity measured with the laser-induced transient thermal grating technique. We find that at a given thermal grating period, the radiative contribution to thermal transport is maximized when the absorption length of thermal radiation is about 1/4 of the period. We present the expression for an upper bound for the radiative contribution and discuss the results for representative materials. We conclude that in a typical transient grating measurement with the grating period in the micrometer range, the radiative contribution is negligible, but it may be significant if the grating period is in the millimeter or centimeter range. Our analysis also provides a Fourier-domain Green's function that can be used to find the temperature field produced by an arbitrary spatiotemporal distribution of heat sources.
Achieving stable fiber coupling of quantum dot telecom C-band single-photons to an SOI photonic device
Authors: Bauer Stephanie , Wang Dongze , Hoppe Niklas , Nawrath Cornelius , Fischer Julius , Witz Norbert , Kaschel Mathias , Schweikert Christian , Jetter Michael , Portalupi Simone L. , Berroth Manfred , Michler Peter
Published: November 2021

The well-established silicon-on-insulator platform is very promising for large-scale integrated photonic and quantum photonic technologies due to the mature manufacturing technology and integration density. Here, we present an efficient and stable fiber-to-chip coupling, which enables the injection of single photons from telecom quantum dots into a silicon-on-insulator photonic chip. Two additional fibers further couple the chip to single-photon detectors. The approach chosen to achieve steady fiber-chip coupling is based on the use of grating couplers steadily packaged with angled single-mode fibers. Using this technique, coupling efficiencies between the fiber and the SOI chip as high as 69.1% per grating coupler (including the taper losses) are reached. The effective interface between the quantum light generated by quantum dots and the silicon components is verified via the measurement of the second-order correlation function using a Hanbury–Brown and Twiss setup. With g(2)(0)=0.051±0.001, it clearly proves the single-photon nature of the injected QD photons. This demonstrates the reliability of the interfacing method and opens the route to employ telecom quantum dots as non-classical light sources with high complexity silicon photonic functionalities.
Finding the order in complexity: The electronic structure of 14-1-11 zintl compounds
Authors: Liu Yukun , Toriyama Michael Y. , Cai Zizhen , Zhao Mengjia , Liu Fei , Jeffrey Snyder G.
Published: November 2021

Yb14MnSb11 and Yb14MgSb11 have rapidly risen to prominence as high-performing p-type thermoelectric materials. However, the fairly complex crystal structure of A14MX11 Zintl compounds renders the interpretation of the electronic band structure obscure, making it difficult to chemically guide band engineering and optimization efforts. In this work, we delineate the valence-balanced Zintl chemistry of A14MX11 compounds using the molecular orbital theory. By analyzing the electronic band structures of Yb14MgSb11 and Yb14AlSb11, we show that the conduction band minimum is composed of either an antibonding molecular orbital originating from the (Sb3)7– trimer or a mix of atomic orbitals of A, M, and X. The singly degenerate valence band is comprised of non-bonding Sb pz orbitals primarily from the Sb atoms in the (MSb4)m– tetrahedra and of isolated Sb atoms distributed throughout the unit cell. Such a chemical understanding of the electronic structure enables strategies to engineer electronic properties (e.g., the bandgap) of A14MX11 compounds.
Entropy and hierarchical clustering: Characterizing the morphology of the urban fabric in different spatial cultures
Authors: Brigatti E. , Netto V. M. , de Sousa Filho F. N. M. , Cacholas C.
Published: November 2021

In this work, we develop a general method for estimating the Shannon entropy of a bidimensional sequence based on the extrapolation of block entropies. We apply this method to analyze the spatial configurations of cities of different cultures and regions of the world. Findings suggest that this approach can identify similarities between cities, generating accurate results for recognizing and classifying different urban morphologies. The hierarchical clustering analysis based on this metric also opens up new questions about the possibility that urban form can embody characteristics related to different cultural identities, historical processes, and geographical regions.
The initiation of shear band formation in deformed metallic glasses from soft localized domains
Authors: Wang Xinyi , Zhang Hao , Douglas Jack F.
Published: November 2021

It has long been thought that shear band (SB) formation in amorphous solids initiates from relatively “soft” regions in the material in which large-scale non-affine deformations become localized. The test of this hypothesis requires an effective means of identifying “soft” regions and their evolution as the material is deformed to varying degrees, where the metric of “softness” must also account for the effect of temperature on local material stiffness. We show that the mean square atomic displacement on a caging timescale ⟨u2⟩, the “Debye–Waller factor,” provides a useful method for estimating the shear modulus of the entire material and, by extension, the material stiffness at an atomic scale. Based on this “softness” metrology, we observe that SB formation indeed occurs through the strain-induced formation of localized soft regions in our deformed metallic glass free-standing films. Unexpectedly, the critical strain condition for SB formation occurs when the softness (⟨u2⟩) distribution within the emerging soft regions approaches that of the interfacial region in its undeformed state, initiating an instability with similarities to the transition to turbulence. Correspondingly, no SBs arise when the material is so thin that the entire material can be approximately described as being “interfacial” in nature. We also quantify relaxation in the glass and the nature and origin of highly non-Gaussian particle displacements in the dynamically heterogeneous SB regions at times longer than the caging time.
Benchmarking isotropic hyperfine coupling constants using (QTP) DFT functionals and coupled cluster theory
Authors: Windom Zachary W. , Perera Ajith , Bartlett Rodney J.
Published: November 2021

Significant effort has been devoted to benchmarking isotropic hyperfine coupling constants for both wavefunction and density-based approaches in recent years, as accurate theoretical predictions aid the fitting of experimental model Hamiltonians. However, literature examining the predictive quality of a Density Functional Theory (DFT) functional abiding by the Bartlett IP condition is absent. In an attempt to rectify this, we report isotropic hyperfine coupling constant predictions of 24 commonly used DFT functionals on a total of 56 radicals, with the intent of exploring the successes and failures of the Quantum Theory Project (QTP) line of DFT functionals (i.e., CAM-QTP00, CAM-QTP01, CAM-QTP02, and QTP17) for this property. Included in this benchmark study are both small and large organic radicals as well as transition metal complexes, all of which have been studied to some extent in prior work. Subsequent coupled-cluster singles and doubles (CCSD) and CCSD withperturbative triples [CCSD(T)] calculations on small and large organic radicals show modest improvement as compared to prior work and offer an additional avenue for evaluation of DFT functional performance. We find that the QTP17 and CAM-QTP00 functionals consistently underperform, despite being parameterized to satisfy an IP eigenvalue condition primarily focused on inner shell electrons. On the other hand, the CAM-QTP01 functional is the most accurate functional in both organic radical datasets. Furthermore, both CAM-QTP01 and CAM-QTP02 are the most accurate functionals tested on the transition metal dataset. A significant portion of functionals were found to have comparable errors (within 5–15 MHz), but the hybrid class of DFT functionals maintains a consistently optimal balance between accuracy and precision across all datasets.
Molecular dynamics study on shock-induced spallation and damage evolution in nano-polycrystalline Ta: Internal grain size effect vs external shock intensity effect
Authors: Wu Dun , Zhu Yaxin , Huang Minsheng , Zhao Lv , Li Zhenhuan
Published: November 2021

As a typical body-centered cubic material, Ta has both high strength and high temperature resistance and is, thus, widely applied in the field of high-energy physics. In this work, the spallation behavior and its underlying physical mechanism of nano-polycrystalline Ta was systematically studied by non-equilibrium molecular dynamics simulations, with special attention to the internal grain size effect vs external shock intensity. The results reveal that the grain size effects on void evolution, spallation strength, and corresponding mechanical and thermodynamic responses are different under different shock intensities. Under the piston velocity of 0.75 km/s, when the grain size decreases from 30 to 2 nm, the spallation mechanism switches from intergranular fracture (d ≥ 10 nm) to cavitation failure (d ≤ 5 nm), and the correlation between spallation strength and grain size also switches from an inverse Hall–Petch to a Hall–Petch relation at a critical grain size dc ∼ 10–20 nm. As the piston velocity increases to 1.5 or 1.8 km/s, a failure mode transition from classical spallation to micro-spallation is observed, leading to a significantly weakened grain size effect on the spallation strength. Through thermodynamic analysis, melting is detected in the tensile region, which is responsible for the micro-spallation. These results can help to understand the effects of internal grain size and external shock intensity on the spallation behavior of Ta and make a leap in the design of shock-resistant materials.
Surface discretization considerations for the boundary-element method applied to three-dimensional ellipsoidal particles in Stokes flow
Authors: Lin Charlie , Wang Shiyan , Narsimhan Vivek , Kim Sangtae
Published: November 2021

The boundary-element method has often been used for simulating particle motion in Stokes flow, yet there is a scarcity of quantitative studies examining local errors induced by meshing highly elongated particles. In this paper, we study the eigenvalues and eigenfunctions of the double layer operator for an ellipsoid in an external linear or quadratic flow. We examine the local and global errors induced by changing the interpolation order of the geometry (flat or curved triangular elements) and the interpolation order of the double layer density (piecewise-constant or piecewise-linear over each element). Our results show that local errors can be quite large even when the global errors are small, prompting us to examine the distribution of local errors for each parameterization. Interestingly, we find that increasing the interpolation orders for the geometry and the double layer density does not always guarantee smaller errors. Depending on the nature of the meshing near high curvature regions, the number of high aspect ratio elements, and the flatness of the particle geometry, a piecewise-constant density can exhibit lower errors than piecewise-linear density, and there can be little benefit from using curved triangular elements. Overall, this study provides practical insights on how to appropriately discretize and parameterize three-dimensional boundary-element simulations for elongated particles with prolate-like and oblate-like geometries.
Spin-valley coupling and valley splitting in the MoSi2N4/CrCl3 van der Waals heterostructure
Authors: Zhao Jun , Jin Xuehu , Zeng Hui , Yao Can , Yan Gang
Published: November 2021

The newly two-dimensional layered materials MA2Z4 (M = Ti/Cr/Mo, A = Si/Ge, Z = N/P/As) possess excellent stability, strong valley-dependent properties, and novel electronic structures. Motivated by recent experimental advances, we have constructed a van der Waals heterostructure consisting of MoSi2N4 and ferromagnetic CrCl3 monolayer and performed first principles calculations to investigate the spin-valley coupling and valley splitting properties. The MoSi2N4/CrCl3 heterostructure is thermally stable at room temperature. Our calculations have shown an enhancement of both valley splitting and valley-contrasting transport properties due to the magnetic proximity effect. Most importantly, the valley-related properties of the MoSi2N4 monolayer are predicated to be rather robust resulting from the protection of the outermost N–Si sublayers. These findings could be helpful to the understanding of the ferromagnetic substrate effect on the valley-dependent properties of MA2Z4-based heterostructures.
Large inverse transient phase response of titanium-nitride-based microwave kinetic inductance detectors
Authors: Hu Jie , Boussaha Faouzi , Martin Jean-Marc , Nicaise Paul , Chaumont Christine , Beldi Samir , Piat Michel , Bonifacio Piercarlo
Published: November 2021

Following optical pulses (λ=405 nm) on titanium nitride microwave kinetic inductance detectors cooled down at temperatures T≤Tc/20 (Tc≃4.6 K), we observe a large phase-response highlighting two different modes simultaneously that are nevertheless related. The first corresponds to the well-known transition of cooper-pair breaking into quasi-particles, which produces a known phase response. This is immediately followed by a large inverse response lasting several hundreds of microseconds to several milliseconds depending on the temperature. We propose to model this inverse pulse as the thermal perturbation of the superconductor and interaction with a two-level system (TLS) that reduces the dielectric constant, which in turn modifies the capacitance and, therefore, the resonance frequency. The ratio of the TLS responding to the illumination is on the order of that of the area of the inductor to the whole resonator.
Genetic variation and cryptic diversity of the
Authors: Cunha Andressa Maria , Terossi Mariana , Mantelatto Fernando Luis , Almeida Alexandre Oliveira
Published: November 2021

Alpheus lobidens sensu lato is one of the most common groups of snapping shrimps in the Indo-West Pacific. The objective of this study was to investigate the phylogenetic relationships among lineages of A. lobidens s.l. throughout their geographical distribution and identifying possible morphological characteristics that support the lineages from this combined dataset. Molecular data were obtained by analysing 16S rRNA from nine individuals of A. lobidens, three of A. buckupi, one of A. inopinatus and six other Alpheus species. The genetic analyses (mean p-distance and Bayesian Inference) indicate considerable genetic divergence and at least nine lineages within the A. lobidens species complex. The high morphological variability observed in Alpheus spp. and the high rates of interspecific genetic divergence agree with the Marine Ecoregions of the World and ocean currents, which suggests limited gene flow among those lineages, indicating that these could be treated as new species. However, as no informative morphological characters were identified, describing the six new taxa of the complex recognised in this study was unfeasible. Future studies using a higher number of specimens and applying more sensitive methods for detecting structural differences, might help morphologically define the new species that were uncovered herein.
Gender stereotypes about interests start early and cause gender disparities in computer science and engineering
Authors: Master Allison , Meltzoff Andrew N. , Cheryan Sapna
Published: November 2021

Significance

Societal stereotypes that girls are less interested than boys in computer science and engineering are endorsed by children and adolescents in a large and socioeconomically diverse sample, across multiple racial/ethnic and gender intersections, and as early as age six (first grade). Gender-interest stereotypes may contribute to subsequent gender disparities in the pursuit of these societally important fields. Addressing interest stereotypes may help improve educational equity.
Exploring the signaling space of a GPCR using bivalent ligands with a rigid oligoproline backbone
Authors: Romantini Nina , Alam Shahidul , Dobitz Stefanie , Spillmann Martin , De Foresta Martina , Schibli Roger , Schertler Gebhard F. X. , Wennemers Helma , Deupi Xavier , Behe Martin , Berger Philipp
Published: November 2021

Significance

G protein–coupled receptors (GPCRs) are major players in cellular signal transmission. In this work, we have used rigid oligoproline backbones derivatized with two ligands at defined distances to induce GPCR dimer formation as a way to alter its signaling profile. We show that bivalent ligands at distances of 20 and 30 Å induce dimers of the GRPR receptor with different signaling responses. In addition, a nondimer–inducing bivalent ligand (with 10-Å distance between agonists) also induces different signaling patterns, most likely due to allosteric effects. These findings identify bivalent ligands with a stiff oligoproline backbone as tools to explore the natural signaling space of GPCRs.
Past insecticide exposure reduces bee reproduction and population growth rate
Authors: Stuligross Clara , Williams Neal M.
Published: November 2021

Significance

Global insect declines are profoundly concerning, especially for groups like bees that provide important services to humanity. However, we do not know the extent to which recognized drivers of decline, like pesticides, may produce carryover effects that influence reproduction and population dynamics over time. We reveal that pesticide exposure, both directly to foraging bees and via carryover effects from past exposure, dramatically reduced bee reproduction, which reduced population growth. Carryover effects reduced bee reproduction by 20% beyond current impacts on foraging bees, exacerbating the negative impact on population growth rates. This indicates that bees may require multiple generations to recover from a single pesticide exposure; thus, carryover effects must be considered in risk assessment and conservation management.
Light-driven dynamic surface wrinkles for adaptive visible camouflage
Authors: Ma Tianjiao , Bai Jing , Li Tiantian , Chen Shuai , Ma Xiaodong , Yin Jie , Jiang Xuesong
Published: November 2021

Significance

Camouflage has broad applications in nature, engineering, and the military. This work demonstrated a feasible strategy for adaptive visible camouflage based on light-driven dynamic surface wrinkles. The multiwavelength light–driven dynamic surface wrinkles based on photothermal effect–induced thermal expansion of the substrate could tune the light scattering and the visibility of the film interference color. Consequently, the color captured by the observer could switch between the exposure state that is distinguished from the background and the camouflage state that is similar to the surroundings, demonstrating the adaptive camouflage. This system is simple to configure, easy to operate, versatile, and exhibits in situ dynamic characteristics without any external sensors and extra stimuli, which provided an alternative strategy for adaptive camouflage.
Warming winters in lakes: Later ice onset promotes consumer overwintering and shapes springtime planktonic food webs
Authors: Hébert Marie-Pier , Beisner Beatrix E. , Rautio Milla , Fussmann Gregor F.
Published: November 2021

Significance

Freshwater ice is being lost at an accelerating rate with global warming. Yet the ecological implications of shortening ice-covered seasons remain largely unexplored due to a historical lack of freshwater research in winter. We provide an innovative experimental study that realistically reproduces warming effects on the timing of ice onset to address the consequences for lake food webs. We find that later ice-on sustains photosynthesis longer, permitting greater accumulation of high-quality fat reserves in primary consumers, and likely facilitating winter survival. Further, we show that a greater prevalence of overwintering consumers shapes springtime food webs via an increased top-down control of the spring algal bloom. Broadly, this study demonstrates that warmer winters can have cross-seasonal cascading effects on ecological processes.
Interactional gestures as soccer celebrations
Authors: Heliasz-Nowosielska Celina
Published: November 2021

The article presents a variety of gesture types used as celebrations during or after soccer matches and explains
the forms, meaning, reference and functions of the gestures as a semiotic phenomenon. The qualitative analysis of media images and
comments on celebratory performances shows that pre-planned, creative celebrations, including trademarks or signatures, which have
recently overshadowed spontaneous, conventionalized displays of affect, take the form of interactional gestures of different
types: performatives, regulators, pointing, icons, metaphors, pantomime, emblems or signs, as well as the form of compositions of
gestures, such as icons and pointing. During the match, gestures of all the above types serve to display affects and take on other
new functions. Also, even gestures like regulators, identified in literature as conversational ones, are used without the
accompanying speech. A disintegrated speech context for the interpretation of the meaning and reference of celebratory gestures is
provided in after-match media discourse.
Exploring the parameter space of modified supergravity for double inflation and primordial black hole formation
Authors: Ishikawa Ryotaro , Ketov Sergei V
Published: November 2021

We study the parameter space of the effective (with two scalars) models of cosmological inflation and primordial black hole (PBH) formation in the modified (R + R
2) supergravity. Our models describe double inflation, whose first stage is driven by Starobinsky’s scalaron coming from the R
2 gravity, and whose second stage is driven by another scalar belonging to the supergravity multiplet. The ultra-slow-roll regime between the two stages leads a large peak (enhancement) in the power spectrum of scalar perturbations, which results in efficient PBH formation. Both inflation and PBH formation are generic in our models, while those PBH can account for a significant part or the whole of dark matter. Some of the earlier proposed models in the same class are in tension (over 3σ) with the observed value of the scalar tilt n
s, so that we study more general models with more parameters, and investigate the dependence of the cosmological tilts (n
s, r) and the scalar power spectrum enhancement upon the parameters. The PBH masses and their density fraction (as part of dark matter) are also calculated. A good agreement (between 2σ and 3σ) with the observed value of n
s requires fine tuning of the parameters, and it is only realized in the so-called δ-models. Our models offer the (super)gravitational origin of inflation, PBH and dark matter together, and may be confirmed or falsified by future precision measurements of the cosmic microwave background radiation and PBH-induced gravitational waves.
Enhance your smartphone with a Bluetooth arduino nano board
Authors: Bouquet F , Creutzer G , Dorsel D , Vince J , Bobroff J
Published: November 2021

Using smartphones in experimental physics teaching offers many advantages in terms of engagement, pedagogy and flexibility. But it presents drawbacks such as possibly endangering the device and also facing the heterogeneity of available sensors on different smartphones. We present a low-cost alternative that preserves the advantages of smartphones: using a microcontroller equipped with a large variety of sensors that transmits data to a smartphone using a Bluetooth low-energy protocol. This device can be lent to students with little risk and used to perform a wide range of experiments. It opens the way to new types of physics teachings.
The role of resonance radiation in the propagation of a positive pre-breakdown ionization wave in long discharge tubes
Authors: Siasko A V , Golubovskii Yu B , Valin S V
Published: November 2021

The work is devoted to calculating the flux of resonance photons towards the boundary of a cylindrical discharge tube of a finite size during the propagation of a pre-breakdown ionization wave of positive polarity. A cylindrical discharge tube of finite dimensions with argon at the pressure of p = 1 Torr is considered. The propagation mechanisms of metastable and resonance atoms are compared. For the considered discharge conditions, the space-time distributions of metastable and resonance atoms are calculated. The manuscript presents a technique for calculating the flux of resonance photons onto the discharge tube wall with the account of the radiation trapping. It is shown that for the studied conditions the photon flux density towards the longitudinal boundary of the tube ahead of the ionization wave can reach 1013 cm−2 s−1. The obtained results allow us to describe the appearance of seed electrons ahead of the positive ionization wavefront during their propagation due to the electron photoemission from the discharge tube wall.
Impact of Joule heating and multiple slips on a Maxwell nanofluid flow past a slendering surface
Authors: Ahmad Shafiq , Khan Muhammad Naveed , Nadeem Sohail , Rehman Aysha , Ahmad Hijaz , Ali Rifaqat
Published: November 2021

This manuscript presents a study of three-dimensional magnetohydrodynamic Maxwell nanofluid flow across a slendering stretched surface with Joule heating. The impact of binary chemical reactions, heat generation, thermal radiation, and thermophoretic effect is also taken into consideration. The multiple slip boundary conditions are utilized at the boundary of the surface. The appropriate similarity variable is used to transfer the flow modeled equations into ODEs, which are numerically solved by the utilization of the MATLAB bvp4c algorithm. The involved parameter’s impact on the concentration, velocity, and temperature distribution are scrutinized with graphs. The transport rates (mass, heat) are also investigated using the same variables, with the results reported in tabulated form. It is seen that the fluid relaxation, magnetic, and wall thickness characteristics diminish the velocities of fluid. Further, the velocity, concentration, and temperature slip parameters reduce the velocities of fluid, temperature, and concentration distribution. The results are compared to existing studies and shown to be in dependable agreement.
Comparison of JET-C DD neutron rates independently predicted by the ASCOT and TRANSP Monte Carlo heating codes
Authors: Weisen H. , Sirén P. , Varje J. , JET Contributors
Published: November 2021

Simulations of the DD neutron rates predicted by the ASCOT and TRANSP Monte Carlo heating codes for a diverse set of JET-C (JET with carbon plasma facing components) plasmas are compared. A previous study (Weisen et al 2017 Nucl. Fusion
57 076029) of this data set using TRANSP found that the predicted neutron rates systematically exceeded the measured ones by factors ranging between 1 and 2. No single explanation for the discrepancies was found at the time despite a large number of candidates, including anomalous fast ion loss mechanisms, having been examined. The results shed doubt on our ability to correctly predict neutron rates also in the deuterium–tritium plasmas expected in the JET D–T campaign (DTE2). For the study presented here the calculations are independently repeated using ASCOT with different equilibria and independent mapping of the profiles of temperature and density to the computational grid. Significant differences are observed between the results from the investigations with smaller systematic differences between neutron rates measurements and predictions for the ones using ASCOT. These are traced back not to intrinsic differences between the ASCOT and TRANSP codes, but to the differences in profiles and equilibria used. These results suggest that the discrepancies reported in reference (Weisen et al 2017 Nucl. Fusion
57 076029) do not require invoking any unidentified plasma processes responsible for the discrepancies and highlight the sensitivity of such calculations to the plasma equilibrium and the necessity of a careful mapping of the profiles of the ion and electron densities and temperatures.
Environmental testing for reliable battery management system in electric vehicle
Authors: Raharjo J , Wikarta A , Sidharta I , Yuniarto M N , Firdaus M I , Zulhaimi M F B
Published: November 2021

The Battery management system (BMS) is a main component in the battery pack system for electric vehicles (EV). The function of BMS is to monitor battery cells such as; cell voltage, cell temperature, and current in the battery pack. Moreover BMS also able to balance the voltage of the cells so the difference in voltage of the cells can be minimized. By having many of these functions, BMS can identify battery health based on these parameters. With such an important function, in this paper, BMS was tested to determine its reliability. The standard testing for BMS reliability is the Environment test. In the environment test, some things that are conducted in the environment test are initial temperature cycling. From the environment, the test can be generated information to assess the quality of the BMS following its function. Furthermore, it can reduce the cost to inspect every battery cells in the packs. With the environment test as a basis for BMS reliability tester, hopefully, good quality is obtained. Future development in BMS reliability testing can also be conducted to improve reliability.
Research on 3D Reconstruction Technology of Power Line Based on Image Semantic Segmentation
Authors: Li Xionggang , Zhang Feng , Li Guoqiang , Xiang Dongwei , Yang Chengcheng
Published: November 2021

Because it was difficult to distinguish the characteristics of the power lines by the traditional methods of extracting the power lines, which led to the current situation of incomplete reconstruction and a large number of noise in the process of rebuilding the power lines only by the inclined photographing. In this paper, the power line information in the image is segmented pixel by pixel by introducing in-depth learning semantics segmenting neural network. The three-dimensional coordinates of the power line are calculated by the principle of multi-view three-dimensional reconstruction. Finally, the power line is fitted by the catenary equation to complete the incomplete power line reconstruction. The results show that the fitted power line model has high accuracy and meets the requirements of power related applications. Based on the traditional three-dimensional reconstruction, a new idea for power line reconstruction is proposed.
Research on Deterministic Measurement Matrix of Power Line Carrier Compressed Sensing
Authors: Jin Jiliang , Xing Liyun , Yang Miao , Shen Jianqiang , Dong Yuqi
Published: November 2021

To verify the advantages of deterministic matrix applied to power line carrier communication (PLCC) based on compressed sensing (CS). This article analyzed the research status of commonly used deterministic measurement matrices, and made simulation comparison. It is found that different types of deterministic measurement matrices generated based on chaotic mapping had higher reconstruction accuracy and higher reconstruction efficiency than Gaussian random matrix. Then, according to simulation results and the characteristics of PLCC signal, the Chebyshev sparse circulant (CSC) measurement matrix was designed by combining eighth-order Chebyshev chaotic and the idea of sparse and circulant. Actual circuit measurement shows that when compression rate was 40% and 60%, the reconstruction loss of CSC is 0.72dB and 0.49dB higher than that of Chebyshev chaotic measurement matrix and Chebyshev circulate measurement matrix, respectively. Obviously, the CSC measurement matrix designed in this paper can effectively improve the reconstruction accuracy.
Research on Optimization of Power System Regulation Capacity Based on New Energy Installed Capacity
Authors: Zhu Yibing , Zhang Jing , Hu Yuou , Cui Fubo , Chu Wenjia
Published: November 2021

As the proportion of new energy continues to increase, the safty and stability of the power system faces severe challenges. Many a flexible resource should be established to ensure that the regulating ability of the power system is enough, so as to cope with the load fluctuations caused by the gird-connected new energy. This article analyses the technical characteristics of various flexible resources, and which aspect that each flexible resource can contribute to the regulating ability of the power system. On this basis, this paper proposes a quantitative analysis method of the improvement of power system regulating ability based on the consumption model of new energy, using the addition of new energy grid-connected capacity as a quantitative indicator to evaluate the improvement of system regulating ability contributed by each type of flexible resource. Combined with calculation examples, a quantitative analysis of usual flexibility resources is carried out.
Simulation and Optimization of Body Structure of Electric Vehicles with Offset Collision
Authors: Hu Yuanhe , Yang Kun , Chen Hao , Wang Jiangbo
Published: November 2021

In recent years, as the rapid growth of the number of electric vehicles, people have more and more requirements on the safety performance of vehicles. However, compared with fuel vehicles, the structure of electric vehicles has its own particularity which makes the safety design of body structure more difficult. Thus, improving the passive safety of electric vehicles and protecting the passengers from injury in the collision to the greatest extent have become important issues for the automotive industry. This paper simulates the frontal offset impact simulation analysis of a certain type of SUV, and analyzes the safety performance of the vehicle from the perspective of member protection. The front side member structure and impact energy absorption which affect the passive safety of the whole vehicle are optimized and improved. The finite element model of the whole vehicle is rebuilt, and the frontal offset impact simulation test is carried out to verify the effectiveness of the optimization scheme.
Acoustic Simulation of the Electric Vehicle Motor
Authors: Li Huibin , Xu Peiyun , Cao Cheng , Hu Dongmei , Yan Xiaojun , Song Zhihuan
Published: November 2021

People pay more and more attention to NVH (N-noise, V-vibration, and H-harshness) characteristics of electric vehicles and motors. The vibration and noise of the electric vehicle motor is a complex multi physical field problem, related to electromagnetic, mechanical, structural and sound fields. In this paper, firstly, the Maxwell electromagnetic field analysis software is used to build the electromagnetic simulation model of PMSM(Permanent magnet synchronous motor) motor, and then the electromagnetic excitation is calculated. Then, the magnetic solid coupling analysis is carried out by using the Maxwell module and harmonic response module of ANSYS Workbench, and the harmonic response of the motor structure under the action of electromagnetic excitation is simulated. After the simulation of magnetic solid coupling is completed, the BEM(Boundary element method) simulation of the permanent magnet synchronous motor is carried out with the acoustic simulation software LMS Virtual Lab. The acoustic simulation of the permanent magnet synchronous motor shows that the sound pressure level at three measurement points have obvious peak value at 3700Hz, 4500Hz, 5400Hz and 6400Hz respectively. The acoustic simulation results lay the foundation for the vibration and noise reduction of the motor.
Constrained Spacecraft Attitude Optimal Control via Successive Convex Optimization
Authors: Wang Jiayao , Shang Haibin
Published: November 2021

Rapid attitude path planning is the key technique in autonomous spacecraft operation missions. An efficient method is proposed for energy-optimal spacecraft attitude control in presence of constraints. Firstly, Gauss pseudospectral method is utilized to discretize and transcribe the primal continuous problem to a nonlinear programming problem. Then a set of convexification techniques are used to convexity the nonlinear programming problem to a series of second-order cone programming problems, which can be solved iteratively by the interior-point method. A solution to the nonlinear programming problem is obtained as the iteration converges. Numerical results show the method could obtain a valid energy-optimal attitude control plan more rapidly than traditional methods.
Automated Classification of High-resolution Rock Image Based on Residual Neural Network
Authors: Cai Weibo , Deng Juncan , Lu Qirong , Lu Kengdong , Luo Kaiqing
Published: November 2021

The identification and classification of high-resolution rock images are significant for oil and gas exploration. In recent years, deep learning has been applied in various fields and achieved satisfactory results. This paper presents a rock classification method based on deep learning. Firstly, the high-resolution rock images are randomly divided into several small images as a training set. According to the characteristics of the datasets, the ResNet (Residual Neural Network) is optimized and trained. The local images obtained by random segmentation are predicted by using the model obtained by training. Finally, all probability values corresponding to each category of the local image are combined for statistics and voting. The maximum probability value and the corresponding category are taken as the final classification result of the classified image. Experimental results show that the classification accuracy of this method is 99.6%, which proves the algorithm’s effectiveness in high-resolution rock images classification.
A Deep Learning Based Automatic Interference Avoidance Resource Allocation Scheme for SCMA Systems
Authors: Yang Peng , Wang Wei , Mao Weimin , Zhang Guoyi , Cai Jie , Hong Danke , Zhu Hailong , Zhang Jianhui , Chen Shengli
Published: November 2021

Sparse code multiple access (SCMA) is able to provide high spectral efficiency and massive connectivity, hence it is considered as a promising scheme for the fifth generation (5G) systems. This paper proposed a radio resource allocation scheme based on deep learning for SCMA systems, with the aim to automatically avoid the inter-cell interference. A long short term memory (LSTM) network is adopted to learn the past interference characteristics and predict the interference power in the current subframe. Radio resource blocks with less predicted interference power are then selected for users to transmit signals. Simulation results show that the proposed scheme outperforms the moving average prediction method and has significant gains over the random radio resource block allocation in terms of achievable bit error rate in SCMA systems.
Evaluation of Vehicle Handling Stability Based on Interval TOPSIS and Entropy Weights
Authors: Huang Xincheng
Published: November 2021

The purpose of this study is to evaluate the handling stability of vehicle from the perspective of users using a multi-criteria decision-making approach with interval numbers. In order to achieve this purpose, the evaluation criteria easy for drivers to understand were constructed based on questionnaire, the interval weights of the criteria were calculated using the entropy weight method with interval numbers, and the interval TOPSIS method was used to evaluate the vehicle handling stability. As the improvement of the method, a new method to determine the crisp value of the interval weight was given, and the relative closeness index used for ranking alternatives was extended to a new additive ranking index. The proposed method was used to evaluate the handling stability of 12 vehicles, and the results may provide some basis for vehicle R & D and design.
Using Windowed Interpolation Method to Suppress Power Frequency Noise of Vibration Signal
Authors: Zhang Xiaotao
Published: November 2021

Power frequency noise interference is widespread. In order to suppress power frequency noise coupled into vibration signal, windowed interpolating method was studied. Firstly, three typical window functions were compared, including rectangular window, Hanning window and six-term cosine window. Secondly, the numerical simulation method was used to analyze the influence of window function on the interpolation results of power frequency noise, finding that different window function should be chose when the spectrum spacing between power frequency noise and useful components of vibration signal is different. Finally, the windowed interpolation method was applied to actual engineering vibration signal to suppress its power frequency noise, with the result that the interpolation result of vibration signal is the most accurate with Hanning window. Numerical simulation and engineering application show that the windowed interpolation method is effective for power frequency noise suppression.
Convolution Diagnosis Model of Centrifugal Pump Based on Fractal Dimension
Authors: Liu Xiaopeng , Sun Bingxiang , Jiang Jiuchun , Zhang Weige , Zhao Chunlu , Zhao Yuzhang , Mao Benqiang , Li Jian , Wang Zhisheng
Published: November 2021

Nowadays, more and more centrifugal pumps are used in the industrial domain. Normal operation of centrifugal pumps is also the key to maintain stable operation of production and process. So it is very important to monitor the operation status of centrifugal pumps real time on-line. In order to diagnose the fault of centrifugal pumps, we proposed a Convolutional Neural Network (CNN) fault diagnosis model, based on Fractal Dimension (FD) features. Firstly, we collected the vibration signal of centrifugal pumps and preprocessed them. Then we used the Empirical Mode Decomposition (EMD) to calculate the fractal dimension and the fractal matrix of the signal. Finally, we constructed the CNN model to diagnose and classify the fault of centrifugal pumps. The experiment shows that the accuracy of the proposed model can reach over 90%.
Path Planning for Construction Machinery Based on Improved Potential Field Ant Colony Algorithm
Authors: Li Peigang , Li Pengcheng , Xie Yining , Feng Xianying , Hu Bin , Tian Congfeng , Zhang Ruwei
Published: November 2021

The path planning algorithm of unmanned construction machinery is studied, and the potential field ant colony algorithm is improved to be applied in the field of unmanned construction machinery. Firstly, the raster map modeling was optimized to eliminate the trap grid in the map. At the beginning of algorithm iteration, the heuristic information of artificial potential field method was added and the global pheromone updating model was improve the convergence speed of the algorithm. In addition, the weight coefficient of potential field force and local pheromone updating model were introduced to enhance the development of raster map in the later iteration of ant colony algorithm and reduce the influence of heuristic information of potential field force. Finally, the selection range of parameters such as optimal pheromone heuristic factor and ant colony number is determined by simulation, and it is verified that the algorithm is better than the basic ant colony algorithm.
Test and Analysis of Stepper Motor’s Noise in HVAC’s Ventilation Valve
Authors: Cai Changxin , Chen Yongjun , Ouyang Ruiling
Published: November 2021

With the application of automotive air conditioning being more popular, higher requirements on automotive air conditioning’s comfort have been put forward, noise is an important criterion about comfort. BDC motor controlling ventilation valve’s noise is mainly caused by brush and commutator, but stepper motor doesn’t have it and stepper motor is cheap and easy-controlling. In this paper, the principle of microstepping drive technology is discussed in detail, the control circuit block diagram and the application of the stepping motor’s control system are introduced. The noise of BDC motor and stepper motor controlling ventilation valve is measured in the semi-anechoic room, BDC motor produces peak noise at the start and stop during the working of motor, stepper motor’s noise is slight and smooth-going; current waveforms have been measured in the microstepping drive, the results show microstepping drive makes current waveform more smooth-going and stepper motor’s noise is lower. So it is a tendance stepper motor will replace BDC motor to control ventilation valve, and the microstepping drive can meet different requirements for merchant’s control.
Optimal Design and Verification of Standing-up Motion Assistant Machine
Authors: Li Shilong , Wang Yue , Zhuang Xing
Published: November 2021

Standing-up motion assistant machine is a new type of assistant device for the care and motion of the semi-disabled, which can replace the manual motion mode to a great extent and reduce the workload of the care-givers. After a detailed analysis of shortcomings of the structural design of the existing standing-up motion assistant machine in the practical application in elderly institutions, this paper proposes a design scheme and mechanical structure of the hanger. The optimized product is verified based on ergonomics theory. Results show that the design scheme and structure of the hanger of the motion assistant machine proposed in this paper can satisfy the requirements of occupant comfort on the premise of ensuring safety, as well as effectively expand the application of the standing-up motion assistant machine in elderly institutions of varied facility levels.