bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of electron conduction on the read noise characteristics in ReRAM devices
Authors: Schnieders K. , Funck C. , Cüppers F. , Aussen S. , Kempen T. , Sarantopoulos A. , Dittmann R. , Menzel S. , Rana V. , Hoffmann-Eifert S. , Wiefels S.
Published: October 2022

The read variability of redox based resistive random access memory is one of the key characteristics with regard to its application in both data storage and novel computation in memory or neuromorphic architectures. While intrinsic noise limits the number of distinguishable states, it may be beneficial for probabilistic computing or to prevent overfitting. Thus, application and material system need to be carefully matched according to their read noise characteristics. Preceding density functional theory simulations suggested dividing oxides used in valence change memory into two categories based on the dominating conduction mechanism. We provide a comprehensive experimental study, which confirms the simulations and demonstrates how the conduction mechanism affects the variability. We analyze the signal-to-noise ratio (SNR) of five different switching oxides, revealing that oxides with shallow defect states (type 1) show high SNR whereas oxides with deep defect states (type 2) exhibit pronounced ionic noise. Thus, our results provide valuable input toward tuning of read noise characteristics by material design.
Migration dynamics of an initially spherical deformable bubble in the vicinity of a corner
Authors: Hasan S. M. Mahfuzul , Hasan A. B. M. Toufique
Published: October 2022

Three-dimensional numerical simulations are performed to study the migration dynamics of a deformable bubble that is spherical at an initial time near a corner formed by two vertical walls. Near-wall dynamics of this rising bubble are studied by investigating its path, wake, shape and velocity. A finite volume approach coupled with VOF (volume-of-fluid) method is adopted to solve the incompressible Navier–Stokes equation and track the gas–liquid interface. From the study, it is found that bubble inertia is dictated by initial bubble–walls interaction as bubble progressively migrates away in a diagonal direction from both the vertical walls in three-dimensional space. This influenced bubble inertia, in turn, affects the conformity of the bubble to a specific bubble regime. Five regimes are identified based on the bubble's migrating trajectory among which three of them are fully developed-steady, zigzag, and spiral and two of them are transitional-steady to zigzag and zigzag to spiral. The point of complete transformation of bubble from steady to zigzag transition to fully developed path instability is evaluated by varying a certain dimensionless parameter, Galilei number Ga. It is found that the path instability occurs at a lower Ga than what it is for the unbounded situations, and the onset of planar zigzag motion is not the result of vortex shedding rather the critical amount of wake accumulation on bubble surface and bubble inertia modulated by walls. Furthermore, the overall dynamics found in the current study show distinguishable characteristics when compared to single wall and unbounded situations.
Addressing the critical parameters for overdamped underwater electrical explosion of wire
Authors: Maler D. , Liverts M. , Efimov S. , Virozub A. , Krasik Ya. E.
Published: October 2022

Experimental and magnetohydrodynamic numerical simulation results and analysis of a μs- and sub-μs-timescale overdamped underwater electrical explosion of copper wires having different lengths and diameters are presented. For these explosions, ∼80% of the energy stored in the pulse generator is deposited into the wire during a time comparable or shorter than a quarter period of the underdamped discharge. It was found that the threshold values of the deposited energy density, energy density rate, and energy density per unit area, which satisfy overdamped discharge, depend on the wire parameters and on the timescale of the explosion. It was shown that the mechanism responsible for this is the process during which the wire experiences phase transitions to a low-ionized plasma, the resistivity of which is determined by the electron–neutral collision rate, which, in turn, depends on the wire radial expansion velocity, current density, and temperature.
Microfluidic devices for quasi-phase-matching in high-order harmonic generation
Authors: Ciriolo A. G. , Martínez Vázquez R. , Crippa G. , Devetta M. , Faccialà D. , Barbato P. , Frassetto F. , Negro M. , Bariselli F. , Poletto L. , Tosa V. , Frezzotti A. , Vozzi C. , Osellame R. , Stagira S.
Published: October 2022

The development of bright eXtreme UltraViolet (XUV) and soft x-ray sources based on high-order harmonic generation is boosting advances toward understanding the behavior of matter on the attosecond timescale. Here, we report a novel approach for efficient XUV generation consisting of the use of microfluidic integrated systems fabricated by femtosecond laser micromachining of glass. Our microfluidic approach allows one to control and manipulate the gas density on a micrometer scale with unprecedented accuracy and micro-structural flexibility. By propagating ultrashort laser pulses inside the microfluidic devices, we demonstrate high photon fluxes and broadband harmonics spectra, up to 200 eV, from tailored gas media.
Thermal stable and low current complementary resistive switch with limited Cu source in amorphous carbon
Authors: Tian Qiaoling , Zhao Xiaoning , Lin Ya , Wang Zhongqiang , Tao Ye , Xu Haiyang , Liu Yichun
Published: October 2022

In this Letter, we report a complementary resistive switch (CRS) with good thermal stability and low ON current. The device is constructed with a bilayer structure composed of sputtered amorphous carbon (a-C) and thermal annealed Cu doped a-C (a-C:Cu). The Cu atoms in a-C:Cu can agglomerate to form nanosized active electrodes by thermal annealing. The Cu species can migrate and redistribute to form conductive filaments within the a-C and a-C:Cu layer through an electrochemical redox reaction. The depletion of Cu species in the a-C:Cu or a-C layer produces complementary resistive switching behaviors. Benefiting from the high thermal stability of a-C and a-C:Cu, the device works stable at a high temperature of up to 300 °C with an endurance of 104 switching cycle and narrow cycle-to-cycle distribution of threshold voltages. Furthermore, the effects of the Cu content in the a-C:Cu layer and the thickness ratio of a-C:Cu/a-C on the ON state current were studied. By limiting the content of Cu in the a-C:Cu layer, a low ON state current of 5 μA was obtained, which is among the lowest in the reported CRSs. Furthermore, a “stateful” material implication logic with the “0” and “1” states represented by a distinct combination of the resistance of each layer was implemented. The CRS is a potential and promising device for low power memory/computing applications and harsh electronics.
Control and suppression of viscous fingering displacing non-Newtonian fluid with time-dependent injection strategies
Authors: Singh Pooja , Mondal Sourav
Published: October 2022

We explore the stabilization mechanism of the fluid–fluid interface in the radial Hele–Shaw cell, displacing a non-Newtonian fluid. It is possible to stabilize the interface following a non-linear injection rate, Q∼t−(2−n)/(2+n), which is related to the displaced fluid rheology (n: power-law index). This suggests the absence of fingering at constant injection when n∼2. We propose a quantitative criterion to control the pattern formation and suppress fingering, through the dimensionless parameter J as a function of the physical and operating parameters, which is applicable for a generalized shear thinning fluid. The parameter J is related to the capillary number in the context of the power-law fluid, relating to the viscous and interfacial forces. The fingering morphology at higher order modes is affected by non-linear effects. The results are non-intuitive, and we have shown a feasible approach toward long term fingering stabilization.
Recent progress and future perspectives on graphene oxide nanoribbons: Dispersion, structure assembly, and applications
Authors: Kwon Ohchan , Kim Ju Yeon , Ji Hyungjoon , Choi Wooyoung , Kim Dae Woo
Published: October 2022

Graphene oxide nanoribbons (GONR) are prepared by the top-down oxidative unzipping of carbon nanotubes. The unique one-dimensional morphology and the abundant functional groups of GONR distinguish it from other graphene-based carbon materials with increased solvent dispersibility and self-assembly behavior. These features have been exploited throughout the literature for various applications, including energy storage materials, sensors, catalysts, fillers for composites, and separation membranes. However, despite its drastically different chemical and physical properties, GONRs are often only discussed in the sub-context of graphene nanoribbons. This Perspective highlights GONRs specifically, focusing on their chemical properties and structuring behaviors, which can be manipulated to yield appealing structures for target applications. These characteristics constitute significant importance in scalable applications. The final section of this Perspective catalogs a comprehensive summary of recent GONR developments and additional perspectives for future research.
α-MoO3–SiC metasurface for mid-IR directional propagation of phonon polaritons and passive daytime radiative cooling
Authors: Erçağlar Veysel , Hajian Hodjat , Rukhlenko Ivan D. , Ozbay Ekmel
Published: October 2022

Various methods for controlling the in-plane propagation direction and topological transitions of phonon polaritons (PhPs) in anisotropic van der Waals (vdW) materials rely on using twisted vdW bi-layers or the hybridization of anisotropic vdW materials with other functional materials such as graphene, hBN, and SiC. At the same time, visibly transparent SiC- and SiO2-based metastructures have potential to solve the problem of daytime radiative cooling. Here, as a unique method, we design a bifunctional α-MoO3-integrated SiC metasurface for effectively controlling the in-plane propagation direction of α-MoO3 PhPs. The control is enabled by a topological transition in the PhP dispersion, which is achieved by proper arrangements of the SiC meta-atoms. The proposed functionality of the designed metasurface is beneficial for the mid-infrared in-plane coupling between quantum emitters and heat management. Moreover, the α-MoO3–SiC metasurface functions as an efficient visibly transparent daytime radiative cooler.
Influence of wall slip in the radial displacement of a yield strength material in a Hele–Shaw cell
Authors: Abedi Behbood , Berghe Lara Schimith , Fonseca Bruno S. , Rodrigues Elias C. , Oliveira Rafael M. , de Souza Mendes Paulo R.
Published: October 2022

The growth of viscous fingers in the radial displacement of a yield strength material confined between the plates of a Hele–Shaw cell is investigated. The apparatus is filled with an aqueous solution of Carbopol® before air is injected to start the displacement process. In addition to striking fingering patterns, we identify unyielded residuals of the Carbopol solution arrested on the plates' surfaces with the assistance of digital mobile microscopes placed above the top plate. These unyielded residuals are subjected to slip conditions on the surface walls and appear in different forms. The experimental observations are correlated with the wall slip behavior detected in rheometric measurements, i.e., observed in the flow curve for shear rates below a critical value. This correlation provides an estimate of a critical propagating radius beyond which shear rates drop to values lower than the critical one, and the influence of wall slip becomes significant. We observe that these residuals are uniformly distributed and appear as thin films where the radii are smaller than the critical value and the wall slip is minimum. However, in locations where the radii are larger than the critical one, the residuals turn into isolated blobs of different sizes, which may propagate in a stick-slip motion radially downstream inside the air fingers. In addition, we observe that the morphology of residuals depends on the gap width between the plates, the injection rate of the invading air, the yield strength of the Carpobol solution, and the wettability conditions of the surface walls.
The central scaffold protein CEP350 coordinates centriole length, stability, and maturation
Authors: Karasu Onur Rojhat , Neuner Annett , Atorino Enrico Salvatore , Pereira Gislene , Schiebel Elmar
Published: October 2022

The centriole is the microtubule-based backbone that ensures integrity, function, and cell cycle–dependent duplication of centrosomes. Mostly unclear mechanisms control structural integrity of centrioles. Here, we show that the centrosome protein CEP350 functions as scaffold that coordinates distal-end properties of centrioles such as length, stability, and formation of distal and subdistal appendages. CEP350 fulfills these diverse functions by ensuring centriolar localization of WDR90, recruiting the proteins CEP78 and OFD1 to the distal end of centrioles and promoting the assembly of subdistal appendages that have a role in removing the daughter-specific protein Centrobin. The CEP350–FOP complex in association with CEP78 or OFD1 controls centriole microtubule length. Centrobin safeguards centriole distal end stability, especially in the compromised CEP350−/− cells, while the CEP350–FOP–WDR90 axis secures centriole integrity. This study identifies CEP350 as a guardian of the distal-end region of centrioles without having an impact on the proximal PCM part.
V-ATPase/TORC1-mediated ATFS-1 translation directs mitochondrial UPR activation in C. elegans
Authors: Li Terytty Yang , Gao Arwen W. , Li Xiaoxu , Li Hao , Liu Yasmine J. , Lalou Amelia , Neelagandan Nagammal , Naef Felix , Schoonjans Kristina , Auwerx Johan
Published: October 2022

To adapt mitochondrial function to the ever-changing intra- and extracellular environment, multiple mitochondrial stress response (MSR) pathways, including the mitochondrial unfolded protein response (UPRmt), have evolved. However, how the mitochondrial stress signal is sensed and relayed to UPRmt transcription factors, such as ATFS-1 in Caenorhabditis elegans, remains largely unknown. Here, we show that a panel of vacuolar H+-ATPase (v-ATPase) subunits and the target of rapamycin complex 1 (TORC1) activity are essential for the cytosolic relay of mitochondrial stress to ATFS-1 and for the induction of the UPRmt. Mechanistically, mitochondrial stress stimulates v-ATPase/Rheb-dependent TORC1 activation, subsequently promoting ATFS-1 translation. Increased translation of ATFS-1 upon mitochondrial stress furthermore relies on a set of ribosomal components but is independent of GCN-2/PEK-1 signaling. Finally, the v-ATPase and ribosomal subunits are required for mitochondrial surveillance and mitochondrial stress-induced longevity. These results reveal a v-ATPase-TORC1-ATFS-1 signaling pathway that links mitochondrial stress to the UPRmt through intimate crosstalks between multiple organelles.
Clonal lineage tracing reveals mechanisms skewing CD8+ T cell fate decisions in chronic infection
Authors: Kasmani Moujtaba Y. , Zander Ryan , Chung H. Kay , Chen Yao , Khatun Achia , Damo Martina , Topchyan Paytsar , Johnson Kaitlin E. , Levashova Darya , Burns Robert , Lorenz Ulrike M. , Tarakanova Vera L. , Joshi Nikhil S. , Kaech Susan M. , Cui Weiguo
Published: October 2022

Although recent evidence demonstrates heterogeneity among CD8+ T cells during chronic infection, developmental relationships and mechanisms underlying their fate decisions remain incompletely understood. Using single-cell RNA and TCR sequencing, we traced the clonal expansion and differentiation of CD8+ T cells during chronic LCMV infection. We identified immense clonal and phenotypic diversity, including a subset termed intermediate cells. Trajectory analyses and infection models showed intermediate cells arise from progenitor cells before bifurcating into terminal effector and exhausted subsets. Genetic ablation experiments identified that type I IFN drives exhaustion through an IRF7-dependent mechanism, possibly through an IFN-stimulated subset bridging progenitor and exhausted cells. Conversely, Zeb2 was critical for generating effector cells. Intriguingly, some T cell clones exhibited lineage bias. Mechanistically, we identified that TCR avidity correlates with an exhausted fate, whereas SHP-1 selectively restricts low-avidity effector cell accumulation. Thus, our work elucidates novel mechanisms underlying CD8+ T cell fate determination during persistent infection and suggests two potential pathways leading to exhaustion.
P38 kinases mediate NLRP1 inflammasome activation after ribotoxic stress response and virus infection
Authors: Jenster Lea-Marie , Lange Karl-Elmar , Normann Sabine , vom Hemdt Anja , Wuerth Jennifer D. , Schiffelers Lisa D.J. , Tesfamariam Yonas M. , Gohr Florian N. , Klein Laura , Kaltheuner Ines H. , Ebner Stefan , Lapp Dorothee J. , Mayer Jacob , Moecking Jonas , Ploegh Hidde L. , Latz Eicke , Meissner Felix , Geyer Matthias , Kümmerer Beate M. , Schmidt Florian I.
Published: October 2022

Inflammasomes integrate cytosolic evidence of infection or damage to mount inflammatory responses. The inflammasome sensor NLRP1 is expressed in human keratinocytes and coordinates inflammation in the skin. We found that diverse stress signals induce human NLRP1 inflammasome assembly by activating MAP kinase p38: While the ribotoxic stress response to UV and microbial molecules exclusively activates p38 through MAP3K ZAKα, infection with arthropod-borne alphaviruses, including Semliki Forest and Chikungunya virus, activates p38 through ZAKα and potentially other MAP3K. We demonstrate that p38 directly phosphorylates NLRP1 and that serine 107 in the linker region is critical for activation. NLRP1 phosphorylation is followed by ubiquitination of NLRP1PYD, N-terminal degradation of NLRP1, and nucleation of inflammasomes by NLRP1UPA-CARD. In contrast, activation of NLRP1 by nanobody-mediated ubiquitination, viral proteases, or inhibition of DPP9 was independent of p38 activity. Taken together, we define p38 activation as a unifying signaling hub that controls NLRP1 inflammasome activation by integrating a variety of cellular stress signals relevant to the skin.
Quantum contribution to luminosity of quasars
Authors: Jacak J.E.
Published: October 2022

The accretion of galactic gas is regarded as the source of the giant luminosity of quasars. The gravitational energy converts itself into radiation close to the Schwarzschild horizon of the central supermassive black hole with efficiency of ca. 30% mass to radiation energy conversion rate. Particularities of such an extremely effective mechanism of mass to energy conversion are, however, still obscure. We propose to take into account quantum statistics properties of fermions, which could emit in close outer vicinity of the Schwarzschild zone a giant energy accumulated in the Fermi spheres of electrons and protons in degenerate quantum collective state created in this region by the gravitational compression of plasma. The release of photons is possible due to the local revoking of Pauli exclusion principle constraint induced by the rapid change of the homotopy of multiparticle trajectories beneath the innermost unstable circular orbit of the black hole, which causes the collapse of Fermi spheres of electrons and protons.
Non-Gaussianity effects on the primordial black hole abundance for sharply-peaked primordial spectrum
Authors: Matsubara Takahiko , Sasaki Misao
Published: October 2022

We perturbatively study the effect of non-Gaussianities on
the mass fraction of primordial black holes (PBHs) at the time of
formation by systematically taking its effect into account in the
one-point probability distribution function of the primordial
curvature perturbation. We focus on the bispectrum and trispectrum
and derive formulas that describe their effects on the skewness and
kurtosis of the distribution function. Then considering the case of
narrowly peaked spectra, we obtain simple formulas that concisely
express the effect of the bi- and trispectra. In particular,
together with the g
NL and τ
NL parameters of the
trispectrum, we find that non-Gaussianity parameters for various
types of the bispectrum are linearly combined to give an effective
parameter, f
NL
eff, that determines the PBH mass
fraction in the narrow spectral shape limit.
Accurate modelling of extragalactic microlensing by compact objects
Authors: Boscá Víctor , Fleury Pierre , García-Bellido Juan
Published: October 2022

Microlensing of extragalactic sources, in particular the probability of significant amplifications, is a potentially powerful probe of the abundance of compact objects outside the halo of the Milky Way. Accurate experimental constraints require an equally accurate theoretical model for the amplification statistics produced by such a population. In this article, we argue that the simplest (strongest-lens) model does not meet this demanding requirement. We thus propose an elaborate practical modelling scheme for extragalactic microlensing. We derive from first principles an expression for the amplification probability that consistently allows for: (i) the coupling between microlenses; (ii) realistic perturbations from the cosmic large-scale structure; (iii) extended-source corrections. An important conclusion is that the external shear applied on the dominant microlens, both by the other lenses and by the large-scale structure, is practically negligible. Yet, the predictions of our approach can still differ by a factor of a few with respect to existing models of the literature. Updated constraints on the abundance of compact objects accounting for such discrepancies may be required.
Dynamical response of a reaction–diffusion predator–prey system with cooperative hunting and prey refuge
Authors: Han Renji , Mandal Gourav , Guin Lakshmi Narayan , Chakravarty Santabrata
Published: October 2022

The present research is concerned with the combined outcome of the cooperative hunting and prey refuge in a spatiotemporal predator–prey model. Firstly, the problem is confirmed to be well-posed and some basic preliminaries are provided within the context of the temporal environment. Subsequently, both the local and the global stability of the temporal system including permanence are thoroughly investigated so as to emerge the fact that the competition between the hunting cooperation factor a and the refuge coefficient r can resolve the dynamics of the system. More precisely, global stability for all of the feasible non-negative equilibria corresponding to the temporal environment and the coexistence equilibrium in the spatiotemporal domain are explored in the event of the hunting cooperation factor a not exceeding the prey refuge coefficient r. However, the moment a exceeds r, where both the Hopf bifurcation and the Turing bifurcation are induced by hunting cooperation. Nevertheless, a distinct Turing instability mechanism is emerged when the prey diffusivity exceeds that of predator but interestingly, the opposite is customarily a reasonable constraint in many predator–prey models. Later on, the diffusion coefficient is chosen as a bifurcation parameter interpreting pattern transition and the amplitude equations close to the onset are thereby derived. The stability analysis is made use of to explain the selection of patterns among hot spot patterns, the mixture of hot spots and stripes patterns and the stripe patterns themselves. Finally, numerical simulations are performed to explore pattern selection influenced by the hunting cooperation factor, the prey refuge coefficient and the diffusivity as well. Some interesting dynamical complexities including the variation of the number of equilibria, the bifurcation scenario, etc, also emerge out from such quantitative simulations.
Non-equilibrium random walks on multiplex networks
Authors: Huang Feng , Chen Hanshuang
Published: October 2022

We introduce a non-equilibrium discrete-time random walk model on multiplex networks, in which at each time step the walker first undergoes a random jump between neighboring nodes in the same layer, and then tries to hop from one node to one of its replicas in another layer. We derive the so-called supra-Markov matrix that governs the evolution of the occupation probability of the walker. The occupation probability at stationarity is different from the weighted average over the counterparts on each layer, unless the transition probabilities between layers vanish. However, they are approximately equal when the transition probabilities between layers are very small, which is given by the first-order degenerate perturbation theory. Moreover, we compute the mean first passage time (MFPT) and the graph MFPT (GrMFPT) that is the average of the MFPT over all pairs of distinct nodes. Interestingly, we find that the GrMFPT can be smaller than that of any layer taken in isolation. The result embodies the advantage of global search on multiplex networks.
Birds on a wire
Authors: Krapivsky P L , Redner S
Published: October 2022

We investigate the occupancy statistics of birds on a wire. Birds land one by one on a wire and rest where they land. Whenever a newly arriving bird lands within a fixed distance of already resting birds, these resting birds immediately fly away. We determine the steady-state occupancy of the wire, the distribution of gaps between neighboring birds, and other basic statistical features of this process. We briefly discuss conjectures for corresponding observables in higher dimensions.
Automatic identification method of topology structure of low-voltage distribution station area based on multi-point measurement data
Authors: Zhou Lei , Ma Jian , Huang Hao , Xia Taibao , Ma Xiaohan
Published: October 2022

In order to improve the accuracy and success rate of the identification results of the topology structure of the station area, an automatic identification method of the topology structure of the low-voltage distribution station area based on multi-point measurement data is proposed. LoRa technology is used to obtain multi-point measurement data, and with the help of protocol compression technology, the acquisition of massive high-density measurement data is completed. A current-based identification model for the affiliation of equipment in the station area is constructed, and the affiliation between the primary branch and the secondary branch, and the affiliation between the secondary branch and the user energy meter cluster set are obtained by using the model. Finally, the DTW distance and cluster analysis are used to analyze the distribution terminal and the collected measurement data. So as to realize the automatic identification of the topology structure of the low-voltage distribution station area. The experimental results show that the identification results of the proposed method are more accurate, and the success rate is also effectively improved.
Modal Research of a Certain Type of Gas Turbine Rotor
Authors: Bian Shiji , Zhang Gang , Li Xu , He Yuliang
Published: October 2022

At present, one of the bottlenecks that currently restrict the reliability and lifetime of the whole machine is the rotor-bearing system of gas turbines. This paper firstly introduces the background of gas turbines and the current research situation, and then carries out 3D modelling using UG (Unigraphics NX) software according to the available 2D drawings of the original rotor and relevant parameters. In view of the complex structure of the original rotor and the technical problems in the actual installation process, the original bearing-rotor system was modified and modelled in 3D as well, followed by modal analysis and Campbell diagrams based on Ansys Workbench software. Finally, the simulation results were compared with the theoretical results to verify the feasibility of the scheme and to provide theoretical support for the subsequent 1:1 gas turbine rotor-bearing performance test-bed for the comprehensive performance experimental study of the research and development of gas turbine bearings.
Vibration Suppression of Electromechanical Actuator Considering Backlash Nonlinearity
Authors: Fu Bangsheng , Qi Hui , Xu Jiangtao , Wang Shaobo
Published: October 2022

As an electromechanical drive system, nonlinear factors are unavoidable in electromechanical actuator (EMA). In this paper, elasticity of shaft and backlash nonlinearity are considered in the model, the effects of elasticity and backlash on EMA are analyzed. In order to suppress the vibration caused by nonlinearity and elasticity, A nonlinear control method based on backstepping method is proposed. The simulation results show that this method can eliminate the limit cycle oscillation (LCO) caused by backlash, and effectively suppress the vibration.
Fault Diagnosis of Transformer Winding Based on VMD-SVM
Authors: Chu Jianxiong , Li Zhenyu , Huang Lipeng , Huang Xueying , Wang Kunming
Published: October 2022

Considering the nonlinear and non-stationary characteristics of the transformer vibration acceleration signal obtained from the surface of the transformer tank, the variational mode decomposition (VMD) theory is introduced. Simulation analysis shows that the VMD decomposition has obvious advantages over EMD when the needle frequency is similar to the signal. It effectively avoids two types of modal aliasing and over-decomposition, and accurately reflects the characteristics of the source signal. Aiming at the problem that the two core parameters of the support vector machine are difficult to determine, the Pareto particle swarm method is used to perform multi-objective parallel optimization of the two core parameters of the support vector machine to obtain the optimal parameters. The VMD-SVM fault diagnosis model is tested using the transformer instance fault data, and compared with the other two methods. The instance test results show that the VMD-SVM proposed in this paper has the highest diagnostic accuracy and realizes the latent fault of the power transformer winding. accurate diagnosis.
Simulation Research of Simplified Dynamic Matrix Control
Authors: Zhang Deli , Wang Na , Pang Chunfeng , Zhu Longfei
Published: October 2022

Aiming at the shortcomings of matrix inversion and large amount of calculation in dynamic matrix control, a simplified algorithm is proposed. The algorithm introduces the expected attenuation factor of control increment to make the control increment gradually close to zero in the control time domain. In this way, the matrix inversion in the algorithm is simplified to pure value inversion (i.e. taking the reciprocal), which greatly reduces the amount of calculation, improves the calculation efficiency and reduces the adjustment of control parameters. Therefore, the real-time performance of the algorithm is strong, It is convenient for microcomputer programming. The simulation results show that the improved DMC algorithm is due to the improved DMC Algorithm in ensuring the real-time performance and the dynamic performance of the controlled object.
Research on the Asynchronous Motor Direct Torque Control
Authors: Zhao Xiaoxiao , Yun Yuxin , Lin Xin
Published: October 2022

In this paper, we have adopted a more improved and advanced direct torque control (DTC) method. On this basis, we have also carried out in-depth research on many aspects of asynchronous motor direct torque control system. Some key conclusions are obtained as follows: (1) in this method, we use MRAC identification model with low pass filter and high pass filter to analyze. (2) A new speed observer is also designed. After comparing with the simulation results of other methods, it is proved that this method is effective and superior, its control performance is better and the identification accuracy is higher, which has important practical significance. (3) In this method, we use the digital signal processor TMS320F240 to build a matching experimental system. The experimental results show that this method is indeed effective. (4) Finally, the application scope and main research directions of the method are pointed out. In the future work, we need to strengthen the research on more advanced and efficient direct torque control (DTC) methods and improve it.
Analysis of modeling and fault line selection method for Single-phase Intermittent fault of distribution network
Authors: Wang Zhenxing , Zhang Haijun , Wang Huayang , Bi Zhijun , He Xiujing , Wang Qi , Yu Xiangzong
Published: October 2022

Intermittent arcing often occurs when a single-phase-to-ground fault occurs in the distribution network. However, the intermittent fault modeling suitable for distribution network fault analysis is not perfect, the ability to handle intermittent arcs is insufficient, and fault line selection is prone to misjudgment. In this paper, based on analyzing the operating voltage and current characteristics of intermittent faults in the resonant grounding system of the distribution network, a simulation model of intermittent grounding faults of the 10kV distribution network is established in PSCAD/EMTDC, and a new method based on transient characteristics is proposed. The line selection method for intermittent faults in the distribution network based on fault transient characteristics is proposed. The simulation results show that the established model is suitable for fault analysis of distribution networks, and the proposed method of fault line selection is fast and correct.
Numerical simulation and analysis of wall temperature based on the tangent oval model under different speed and radiation conditions
Authors: Wei Biao , Weng Xiaolong , Yuan Le , Qi Lun , Huang Gang , Du Xingbo , Bi Mei
Published: October 2022

In this paper, the influence mechanism of flight speed, altitude and emissivity of skin material on the temperature of aircraft wall were systematically analysed by numerical simulation. The results show that the increase of the velocity would lead to the rise of the wall pressure and temperature of the aircraft. In addition, a speed of 5 Ma and flight altitude at 30 km, the heat transmitted to the outside was reduced with the decrease of skin material emission. As a result, the constant increase of its own heat energy, which led to the continuous rise of the wall temperature of the aircraft. And the total target radiation emission was reduced by 58.8% with the decrease of emissivity (from 0.8 to 0.2). These results show that the infrared radiation of the aircraft could effectively be suppressed by low emissivity material, the infrared stealth performance of aircraft was enhanced. The research has guiding significance for the temperature-resistant characteristics of skin materials and infrared radiation control.
Trochoidal milling chip thickness model based on real trajectory
Authors: Zhou Ke , Zhang Changming , Du Siyuan
Published: October 2022

With the progress of science and technology industrial development on the use of parts performance and requirements continue to improve, difficult-to-machine materials are more and more widely used, in order to better predict the difficult-to-machine materials milling process cutting force and other parameters, the traditional equivalent chip thickness can no longer meet the calculation accuracy, so it is necessary to describe the chip thickness according to the real trajectory of the cutting edge, using the numerical solution method to find out the intersection between the tool track and the tool track. Thus, the chip geometry during milling is obtained, the instantaneous chip thickness is obtained by solving the transcendental equation, and the chip thickness model is numerically simulated, and finally the chip thickness model in this paper is compared with the traditional chip thickness model, and it is found that this model can better reflect the chip thickness in the machining process.
Research on Frequency Transmission Scheme of Wind Farm in the Scenario of DC Islanding
Authors: Song Yu , Wu Shouyuan , Wang Qian , Li Weichao
Published: October 2022

With the wide application of new energy technologies, wind power has become one of the technologies with the largest development scale. Voltage Source Converter based High Voltage Direct Current Transmission system has unique advantages in its active and reactive power decoupling control, etc., and has become the main solution to solve the wind power transmission of large-scale wind farms. This paper studies the control characteristics and basic principles of new energy generation in the passive transmission system of DC island power grids, and proposes a frequency signal transmission scheme in the external transmission scenario. The simulation results verify the feasibility of the frequency signal transmission scheme between the sending-end wind farm and the receiving-end power grid in the DC islanding scenario, and that the VSC-HVDC system can quickly provide active power support and improve the dynamic frequency stability of the interconnected system.
Risk assessment of voltage sag based on multi-source data mining
Authors: Fu Zhiwei , Lin Yan , Lin Fang , Huang Daoshan , Fang Xiaolin
Published: October 2022

This paper proposes the data mining method of voltage sag severity based on DHP algorithm and replaceable coefficient to assess the risk of voltage sag. The DHP (Direct Hashing and Pruning) is served to mine the relationship between voltage sag characteristic attribute (VSCA) in the fault scenario and the voltage sag severity (VSS) of node. Using direct hash pruning technology, frequent item sets can be found quickly and mining efficiency can be improved. The association rules are matched with the actual fault scenarios through replaceable coefficients to get the VSS of actual fault scenarios. Finally, the effectiveness and accuracy of this method are verified by simulation and examples.
Properties of silicon-based lithium batteries with different electrode nanostructures
Authors: Huang Qiuming , Liu Guangyao , Xie Zehao
Published: October 2022

Among the energy storage devices, lithium-based batteries demonstrate extraordinary performance, which makes them a promising substitution for fossil fuels. Although lithium-based batteries are now used on a large scale, there are still some drawbacks in the basic components of the battery that limit its further application In recent decades, researchers have focused greatly on the refinement of the nanostructure of electrode materials. Nanostructures are highly promising candidates for solving these problems of the lithium-based battery, whose large specific area, considerable active points, and many extraordinary properties derived from its minimum size, especially gather attention from researchers. This review article will emphasize the strategies used by researchers to help them overcome the drawbacks they face. Moreover, this review discusses these strategies at the level of different dimensions, which helps us to optimize the design of lithium batteries from a more integrated perspective. To give a clearer picture of the lithium-based battery developments, this review also summarizes the recent advancement of nanostructures applied in lithium-based batteries
Study on electrical properties of polyethylene after immersed into water
Authors: Li Lili , Han Gang , Zhang Qianping , Chu Xianmin , Tan JingYang , Liu Wenfeng
Published: October 2022

When the cable insulation is in the humid environment for a long time, the electricity property of insulation gradually decreases, and then the normal transmission of power may be failing. In this paper, in order to study the water resistance of polyethylene (PE), the variation of electrical parameters of PE with immersion time is tested. The experimental results show that when PE is immersed into the water, the electrical properties of dielectric decrease to some extent. After immersion for 165h, the relative permittivity εr
and the loss tangent tan δ increases by 0.37 and 0.0007, respectively. And the volume resistivity ρv
and the breakdown field strength Eb
decreases by 3.37×1017Ω.cm and 20.54kV/mm, respectively. Finally, the functional relationships between parameters and immersion time are established, and the relationships between four parameters and immersion time are obtained.
Simulation study on electrical properties of p-GaN gate normally-off HEMT devices affected by Al mole fraction in AlGaN barrier layer
Authors: Xiong Songming , Huang Wenxian , Hassan Ali , Zhong Rong
Published: October 2022

The reason that p-GaN gate normally-off high electron mobility transistor (HEMT) device is able to draw prevail interests is not only for its outstanding electric properties of low on-resistance and high thermal conductivity, but also for its applications under high frequency and high voltage. In HEMT devices, the setting of Al component in the AlGaN barrier layer is a key parameter to affect the formation of two-dimensional electron gas (2DEG) at the AlGaN/GaN heterojunction, and therefore directly determines the performance of the devices. This paper uses the Atlas module of the Silvaco-TCAD software to design and simulate p-GaN gate normally-off HEMT devices to investigate the effect of Al mole fraction content in the AlGaN barrier layer on the electrical performance, as well as the causes in terms of the conduction band energy structure diagram. The results show that the threshold voltage of the HEMT device decreases, the maximum saturation drain current increases, and the peak transductance of the HEMT device increases with increasing the Al content. In the off-state (zero gate voltage), the AlGaN/GaN potential well depth becomes deeper as the Al mole fraction increases, resulting in a lower driven force to rebuild the minimized 2DEG concentration in the GaN layer for switching from off-state to on-state, and this leads to a lower threshold voltage. While, in the on-state (5 V gate voltage), the deeper AlGaN/GaN potential well depth as the Al mole fraction increases, the higher of the 2DEG concentration of the GaN layer, leading to a higher maximum saturation output drain current. After optimization, the integrated electrical performance of the HEMT devices has been found best when the Al mole fraction content is about 0.25. The results obtained from the simulations are helpful for the experimental design of p-GaN gate normally-off HEMT devices
Study on Lubricating Performance of Soft Slider Bearing in Conformal Contact
Authors: Wang Leizhen , Wang Wen , Chen Shangjun , Bai Yujian
Published: October 2022

In this paper, the lubricating performance of soft slider bearing in conformal contact is analyzed. Compared with the hard slider, the soft slider will have greater elastic deformation under low pressure. Three kinds of sliders with different elastic modulus are used for comparative study in this paper. The materials of the three sliders are: steel, glass and PMMA. A hydrodynamic lubrication model of conformal contact considering elastic deformation is established according to the theory of fluid lubrication. A program for calculating dynamic pressure lubrication performance of conformal contact considering elastic deformation is developed by using Matlab and Comsol. The influence of different inclination, different speed and different load on hydrodynamic lubrication performance was studied respectively. The results show that under the same conditions, the elastic deformation on the surface of the slider is more conducive to the formation of oil film, and more conducive to the conditions of high load.
Structural Analysis of Battery Pack Box for New Energy Vehicles Based on the Application of Basic Foam Aluminum Materials
Authors: Ma Congcheng , Hou Jihong , Lan Fengchong , Cheng Jiqing
Published: October 2022

The box structure of the power battery pack is an important issue to ensure the safe driving of new energy vehicles, which required relatively better vibration resistance, shock resistance, and durability. Its structural safety is closely related to the life safety and property safety of drivers and passengers, which is an important index to the structural safety of new energy vehicles. In this work, the structure of the new energy vehicle is optimized by a finite element model, and the side crashworthiness applied to the electric vehicle is analyzed by means of a rigid column. To this end, the key components of the box structure of the battery pack box were optimized base on the application of foam aluminum material, which can effectively reduce the vehicle mass and improve vehicle safety.
Effect of diffusion on the peak value of energy loss observed in a LArTPC
Authors: Putnam G. , Schmitz D.W.
Published: October 2022

Liquid Argon Time Projection Chamber (LArTPC) detectors
observe ionization electrons to measure charged particle
trajectories and energy. In a LArTPC, the long time (∼ms)
between when the ionization is produced and when it is collected
means that diffusion can smear the charge by an amount comparable to
the spatial resolution of the detector, given by the spacing between
charge sensing channels (∼mm). This smearing has an impact on
the distribution of energy losses measured by each channel. In
particular, the smearing increases the length of the charged
particle trajectory observed by each channel, and therefore the
most-probable-value (MPV) of particle energy loss recorded by that
channel. We find, for example, that this effect shifts the MPV 
dE/dx of a muon with an energy of 1 GeV by ∼4% for a
2 ms drift time and 4.7 mm wire spacing, as in the DUNE-FD LArTPC.
This has implications for the energy-scale calibration and electron
lifetime measurements in a LArTPC, which both use the MPV of the
muon energy loss distribution as a “standard candle”. The impact
of diffusion on these calibrations is assessed.
Post-operative electrical muscle stimulation attenuates loss of muscle mass and function following major abdominal surgery in older adults: a split body randomised control trial
Authors: Hardy Edward J , Hatt Jacob , Doleman Brett , Smart Thomas F , Piasecki Matthew , Lund Jonathan N , Phillips Bethan E
Published: October 2022

Introduction

Significant losses of muscle mass and function occur after major abdominal surgery. Neuromuscular electrical stimulation (NMES) has been shown to reduce muscle atrophy in some patient groups, but evidence in post-operative patients is limited. This study assesses the efficacy of NMES for attenuating muscle atrophy and functional declines following major abdominal surgery in older adults.

Methods

Fifteen patients undergoing open colorectal resection completed a split body randomised control trial. Patients’ lower limbs were randomised to control (CON) or NMES (STIM). The STIM limb underwent 15 minutes of quadriceps NMES twice daily on post-operative days (PODs) 1–4. Ultrasound measurements of Vastus Lateralis cross-sectional area (CSA) and muscle thickness (MT) were made preoperatively and on POD 5, as was dynamometry to determine knee extensor strength (KES). Change in CSA was the primary outcome. All outcomes were statistically analysed using linear mixed models.

Results

NMES significantly reduced the loss of CSA (−2.52 versus −9.16%, P < 0.001), MT (−2.76 versus −8.145, P = 0.001) and KES (−10.35 versus −19.69%, P = 0.03) compared to CON. No adverse events occurred, and patients reported that NMES caused minimal or no discomfort and felt that ~90-minutes of NMES daily would be tolerable.

Discussion

NMES reduces losses of muscle mass and function following major abdominal surgery, and as such, may be the promising tool for post-operative recovery. This is important in preventing long-term post-operative dependency, especially in the increasingly frail older patients undergoing major abdominal surgery. Further studies should establish the efficacy of bilateral NMES for improving patient-centred outcomes.