bluuebunny/crossref_metadata_2025 huggingface dataset:
Learn to synchronize, synchronize to learn
Authors: Verzelli Pietro , Alippi Cesare , Livi Lorenzo
Published: August 2021

In recent years, the artificial intelligence community has seen a continuous interest in research aimed at investigating dynamical aspects of both training procedures and machine learning models. Of particular interest among recurrent neural networks, we have the Reservoir Computing (RC) paradigm characterized by conceptual simplicity and a fast training scheme. Yet, the guiding principles under which RC operates are only partially understood. In this work, we analyze the role played by Generalized Synchronization (GS) when training a RC to solve a generic task. In particular, we show how GS allows the reservoir to correctly encode the system generating the input signal into its dynamics. We also discuss necessary and sufficient conditions for the learning to be feasible in this approach. Moreover, we explore the role that ergodicity plays in this process, showing how its presence allows the learning outcome to apply to multiple input trajectories. Finally, we show that satisfaction of the GS can be measured by means of the mutual false nearest neighbors index, which makes effective to practitioners theoretical derivations.
Noise robust approach to reconstruction of van der Pol-like oscillators and its application to Granger causality
Authors: Sysoev Ilya V. , Bezruchko Boris P.
Published: August 2021

Van der Pol oscillators and their generalizations are known to be a fundamental model in the theory of oscillations and their applications. Many objects of a different nature can be described using van der Pol-like equations under some circumstances; therefore, methods of reconstruction of such equations from experimental data can be of significant importance for tasks of model verification, indirect parameter estimation, coupling analysis, system classification, etc. The previously reported techniques were not applicable to time series with large measurement noise, which is usual in biological, climatological, and many other experiments. Here, we present a new approach based on the use of numerical integration instead of the differentiation and implicit approximation of a nonlinear dissipation function. We show that this new technique can work for noise levels up to 30% by standard deviation from the signal for different types of autonomous van der Pol-like systems and for ensembles of such systems, providing a new approach to the realization of the Granger-causality idea.
A cryostat designed for x-ray fluorescence holography experiments down to 4 K
Authors: Hayashi Kouichi , Happo Naohisa , Hosokawa Shinya
Published: August 2021

A cryostat was designed for x-ray fluorescence holography (XFH) experiments at low temperatures down to 4 K, where many functional materials show characteristic transitions, such as high-temperature superconducting, magnetic, dielectric, and valence transitions. For XFH measurements, changes in two angles of samples with respect to the incident synchrotron x-ray beam, i.e., incident angle θ and azimuthal angle ϕ, are necessary. A low-temperature specialized small piezoelectric motor is installed at the cryostat head for ϕ, and the cryostat itself is rotated by a stepping motor for θ. The heat from the piezoelectric motor for ϕ and the cryostat power determining the total cryostat mass were optimized for the limited working spaces and beamtimes of synchrotron experiments. Some examples of the XFH results at low temperatures, such as a Pb crystal and an YbInCu4 valence transition material, are presented to show the feasibility of this low-temperature equipment.
Ultrawideband, high-power, microstripline test setup for experimental study and characterization of multipactor
Authors: Mirmozafari M. , Behdad N. , Booske J. H.
Published: August 2021

This paper discusses different components of a high-power test setup for replicating multipactor in a laboratory environment. We developed a broadband test cell for parallel-plate multipactor discharges that can operate from DC to 1.2 GHz. The proposed test cell design features a multi-step transition from a coaxial line to a microstripline with negligible insertion loss suitable for high-power breakdown experiments. The multipactor section is adjustable and replaceable, offering flexibility in conducting various multipactor tests, such as different gap distances and local surface treatments. We incorporated two local multipactor detection methods, an electron multiplier tube and a biased standalone probe to rapidly and reliably detect the growth of secondary electrons in the multipactor vicinity. The driving circuits of these detection methods have been designed to filter out RF coupling while preserving the detection signal due to multipactor current. To demonstrate the accuracy of the proposed test setup, we validated the multipactor thresholds determined in simulation using the 3D particle-in-cell module of CST Microwave Studio. We obtained very good agreement between simulation and experimental results over the broadband frequency range. The topics discussed in this paper further inform how to address the design obstacles encountered in developing a bench-top multipactor test setup.
OH-Si complex in hydrogenated n-typeβ-Ga2O3:Si
Authors: Venzie Andrew , Portoff Amanda , Fares Chaker , Stavola Michael , Fowler W. Beall , Ren Fan , Pearton Stephen J.
Published: August 2021

Si is an n-type dopant in Ga2O3 that can be intentionally or unintentionally introduced. The results of Secondary Ion Mass Spectrometry, Hall effect, and infrared absorption experiments show that the hydrogen plasma exposure of Si-doped Ga2O3 leads to the formation of complexes containing Si and H and the passivation of n-type conductivity. The Si-H (D) complex gives rise to an O-H (D) vibrational line at 3477.6 (2577.8) cm−1 and is shown to contain a single H (or D) atom. The direction of the transition moment of this defect has been investigated to provide structure-sensitive information. Theory suggests possible structures for an OH-Si complex that is consistent with its observed vibrational properties.
Effect of vacancy defects in 2D vdW graphene/h-BN heterostructure: First-principles study
Authors: Neupane Hari Krishna , Adhikari Narayan Prasad
Published: August 2021

Graphene (G) and hexagonal Boron Nitride (h-BN) are structurally similar materials but have very different electronic and magnetic properties. Heterostructures formed by the combination of these materials are of great research interest. To assess the role played by the crystalline defects in such heterostructures is also of crucial importance owing to their novel properties. In the present work, we study the structural, electronic, and magnetic properties of the G/h-BN heterostructure and the different possible point defects of B and N atoms in it by using first-principles calculations based on the spin-polarized density functional theory (DFT) method within the van der Waals correction DFT-D2 approach. The structural analysis of these systems shows that they are stable two dimensional van der Waals heterostructure materials. Band structure calculations of these materials reveal their semimetallic nature. On the basis of density of states and partial density of states calculations, the defective systems are magnetic materials. The magnetic moment obtained in these defective systems is due to the unpaired up-spin and down-spin states in the orbitals of C, B, and N atoms created by the vacancy defects. On the other hand, the G/h-BN heterostructure has an approving condition for ferromagnetism due to the presence of flat bands in the neighborhood of the Fermi energy.
High-throughput and versatile design for multi-layer coating deposition using lab automation through Arduino-controlled devices
Authors: Hnatiuk Michael , Kimball Dave , Kolanthai Elayaraja , Neal Craig J. , Kumar Udit , Sakthivel Tamil Selvan , Seal Sudipta
Published: August 2021

Laboratory and experimental scale manufacturing processes are limited by human error (e.g., poor control over motion and personal subjectivity), especially under fatiguing conditions involving precise, repetitive operations, incurring compounding errors. Commercial layer-by-layer (LbL) automation devices are prohibitively high-priced (especially for academic institutions) with limited flexibility in form factor and potentially software-associated constraints/limitations. In this work, a novel automated multi-beaker dip coater was fabricated to facilitate nano cerium oxide/polymer coatings via an LbL dip coating process and the synthesis of nano ceria films via a novel successive ionic layer adsorption and reaction method on a glass substrate. Automation of tasks, such as those mediating the detailed procedures, is essential in producing highly reproducible, consistent products/materials as well as in reducing the time commitments for laboratory researchers. Herein, we detail the construction of a relatively large, yet inexpensive, LbL coating instrument that can operate over 90 cm in the horizontal axis, allowing, for example, up to eight 200 ml beakers with accompanying stir plates. The instrument is operated by simple “off-the-shelf” electronics to control the path and timing of the samples with open-source software while providing precision at ±0.01 mm. Furthermore, 3D-printed components were used to maximize the number of substrates that could be coated simultaneously, further improving the sample production rate and reducing waste. Further possibilities for automation beyond the detailed device are provided and discussed, including software interfaces, physical control methods, and sensors for data collection/analysis or for triggers of automated tasks.
Excess wings and asymmetric relaxation spectra in a facilitated trap model
Authors: Scalliet Camille , Guiselin Benjamin , Berthier Ludovic
Published: August 2021

In a recent computer study, we have shown that the combination of spatially heterogeneous dynamics and kinetic facilitation provides a microscopic explanation for the emergence of excess wings in deeply supercooled liquids. Motivated by these findings, we construct a minimal empirical model to describe this physics and introduce dynamic facilitation in the trap model, which was initially developed to capture the thermally activated dynamics of glassy systems. We fully characterize the relaxation dynamics of this facilitated trap model varying the functional form of energy distributions and the strength of dynamic facilitation, combining numerical results and analytic arguments. Dynamic facilitation generically accelerates the relaxation of the deepest traps, thus making relaxation spectra strongly asymmetric, with an apparent “excess” signal at high frequencies. For well-chosen values of the parameters, the obtained spectra mimic experimental results for organic liquids displaying an excess wing. Overall, our results identify the minimal physical ingredients needed to describe excess processes in the relaxation spectra of supercooled liquids.
Effect of magnetic induction on the synchronizability of coupled neuron network
Authors: Rajagopal Karthikeyan , Jafari Sajad , Karthikeyan Anitha , Srinivasan Ashokkumar
Published: August 2021

Master stability functions (MSFs) are significant tools to identify the synchronizability of nonlinear dynamical systems. For a network of coupled oscillators to be synchronized, the corresponding MSF should be negative. The study of MSF will normally be discussed considering the coupling factor as a control variable. In our study, we considered various neuron models with electromagnetic flux induction and investigated the MSF’s zero-crossing points for various values of the flux coupling coefficient. Our numerical analysis has shown that in all the neuron models we considered, flux coupling has increased the synchronization of the coupled neuron by increasing the number of zero-crossing points of MSFs or by achieving a zero-crossing point for a lesser value of a coupling parameter.
Perspectives of Australian GPs on tailoring fall risk management: a qualitative study
Authors: Mackenzie Lynette , Liddle Jeannine , Clemson Lindy M. , Tan Amy C. W. , Lovarini Meryl , Pit Sabrina W. , Poulos Roslyn G. , Roberts Chris , Pond Constance D. , Willis Karen
Published: August 2021

Falls among older people are highly prevalent, serious and costly, and translation of evidence about falls prevention needs to occur urgently. GPs can identify older people at risk of falling and put preventative measures in place before a fall. Because GPs are key to identifying older people at risk of falls and managing falls risk, this study explored how GPs adapted to the iSOLVE (Integrated SOLutions for sustainable falls preVEntion) process to embed evidence-based falls prevention strategies within primary care, and whether and how they changed their practice. A theoretically informed qualitative study using normalisation process theory was conducted in parallel to the iSOLVE trial to elicit GPs’ views about the iSOLVE process. Data were coded and a thematic analysis of interview transcripts was conducted using constant comparison between the data and themes as they developed. In all, 24 of 32 eligible GPs (75%) from general practices located in the North Sydney Primary Health Network, Australia, were interviewed. Six themes were identified: (1) making it easy to ask the iSOLVE questions; (2) internalising the process; (3) integrating the iSOLVE into routine practice; (4) addressing assumptions about patients and fall prevention; (5) the degree of change in practice; and (6) contextual issues influencing uptake. The iSOLVE project focused on practice change, and the present study indicates that practice change is possible. How GPs addressed falls prevention in their practice determined the translation of evidence into everyday practice. Support tools for falls prevention must meet the needs of GPs and help with decision making and referral. Fall prevention can be integrated into routine GP practice through the iSOLVE process to tailor fall risk management. Trial Registry. This trial was registered with the Australian New Zealand Clinical Trial Registry (www.anzctr.org.au; Trial ID: ACTRN12615000401550).
Neural excitability increases with axonal resistance between soma and axon initial segment
Authors: Fékété Aurélie , Ankri Norbert , Brette Romain , Debanne Dominique
Published: August 2021

Significance

Action potentials initiate in the axon initial segment (AIS), close to the soma. Previous experimental findings suggested that a distal shift in AIS position reduces excitability, but theoretical work predicts the opposite. A distal shift in AIS position corresponds to an elevation of axial resistance (
R

a

) between soma and AIS. We modified
R

a

and measured the voltage threshold (V
th
) of action potentials in the soma of cortical neurons. Increasing
R

a

by mechanically pinching the axon hillock lowered V
th
by ∼6 mV, whereas decreasing
R

a

by substituting internal ions with higher mobility elevated V
th
. Thus, excitability increases with axial resistance and therefore with a distal shift of the AIS.
Interfacial hydration determines orientational and functional dimorphism of sterol-derived Raman tags in lipid-coated nanoparticles
Authors: An Xingda , Majumder Ayan , McNeely James , Yang Jialing , Puri Taranee , He Zhiliang , Liang Taimeng , Snyder John K. , Straub John E. , Reinhard Björn M.
Published: August 2021

Significance

Derivatized sterols and terpenoids represent an effective platform for introducing functionality into the surface of lipid-coated NPs and other membrane-based materials. This work demonstrates that the hydrogen-bonding network (HBN) at the lipid–water interface plays a crucial role in determining the orientation of derivatized sterols and other terpenoids in hybrid lipid membranes. A rational engineering of the interactions with the HBN provides control over the molecular orientation in the lipid coating and facilitates configurable surface properties that adjust in response to external cues. The control of the surface properties combined with the plasmonic signal enhancement through the NP core renders L-NPs bright Raman tags for the identification of biomarker overexpression at the single-cell level.
Assessment of socio-ecological resilience of agropastoralists to climate change and variability impacts in Bariadi district, Tanzania.
Authors: Cyrilo Eugen , Mung'ong'o Claude G.
Published: August 2021

In developing countries like Tanzania, societal vulnerability to the risks of climate change and variability (CC&V) exacerbate ongoing social and economic challenges because people's livelihoods are largely dependent on resources that are sensitive to climate change such as agriculture. Although studies show that most communities in Africa have low adaptive capacity, for centuries people have developed traditional adaptation strategies to face climate inter-annual variability and extreme events based on their long-term experiences. Various studies show how CC&V have impacted the socio-economic and and environmental conditions among the pastoral and agropastoral societies. However, little emphasis has been given to studying the community's resilience status to CC&V impacts. Much of the focus has been placed on studying the community vulnerability and impacts of CC&V as well as coping and adaptation strategies to avert CC&V impacts. Little is known on how the interaction between society and nature can enhance or reduce community resilience under changing climate. The study was conducted in two villages, Ibulyu and Mahaha, in Bariadi District. The main objective of the study was to deepen our understanding of the socio-ecological resilience of agropastoral communities to CC&V impacts in a semi-arid district. The study employed both qualitative and quantitative research designs. Quantitative data were captured through a household survey whereas qualitative data was collected through focus group discussion, key informant interviews and field observation. The results show that CC&V have negatively affected the farming system in the study area. The ecological setting of the area has significantly been altered to the extent that it cannot provide the required ecosystem services and products that are important for human and livestock sustainance. Changes in the production system have negatively affected community resilience and increased their vulnerability.
The effects of assisted and resisted plyometric training on jump height and sprint performance among physically active females
Authors: Strate Morten , Stien Nicolay , Saeterbakken Atle Hole , Andersen Vidar
Published: August 2021

The aim of the present study was to compare the effects of assisted and resisted plyometric jump training on jump height, sprint performance (acceleration (0–20m), maximum speed (30–40m) and 40m sprint time) among physically active females. Fifty‐six participants (age: 21.1 ± 1.7 years; body mass: 64.2 ± 7.0 kg; height: 168.0 ± 5.6 cm) were randomly allocated to either an assisted (n = 16) or resisted training group (n = 17), or a control group (n = 14). Nine participants dropped out during the intervention. The training sessions consisted of three different plyometric jump exercises over an eight‐week period, while the control group continued their normal training routine. The results revealed a significant between‐group difference in jump height and maximal speed. The resisted training group achieved a significantly greater improvement in jump height compared to the active control group (p = .04, ES=1.06), and a significantly greater improvement in maximal speed (p = .02, ES = 0.93) when compared to the assisted training group. No other group differences were observed for jump height, acceleration or in maximal speed (p = .31–.53). The resisted training group improved jump height (p = .01, ES = 0.62) and maximum speed (p = .03, ES = 0.48) from pre‐ to post‐test, while the control group improved maximal speed (p = .04, ES = 0.37) and acceleration (p = .01, ES = 0.68). All three groups improved their 40m sprint time from pre‐ to post‐test (p = .01–.04, ES = 0.38–0.45). In conclusion, resisted plyometric training was more effective than assisted plyometric training for improving the maximal speed and more effective than the active control condition for increasing jump height.
Near-field electromagnetic coupling between helices
Authors: Petrov P , Hibbins A P , Sambles J R
Published: August 2021

A fresh approach to the design of metamaterials formed from closely spaced helices is developed based on the retrieved values of electric and magnetic coupling coefficients between adjacent helices. A coupling retrieval method has been implemented to obtain numerical and experimental values for both electric- and magnetic-coupling coefficients between helical elements. Couplings between both right- and left-handed helices in side-by-side and axial arrangements are evaluated providing both positive and negative electric-, as well as magnetic-coupling components. The dependence of coupling strength on separation distance, relative axial rotation, helical pitch and the geometrical arrangement of the helices has been quantified both numerically and experimentally and a geometry giving zero net-coupling between very close helices is illustrated.
Sub-gap Fano resonances in a topological superconducting wire with on-site Coulomb interactions
Authors: Stefański Piotr
Published: August 2021

We consider theoretically a 1D-semiconducting wire with strong Rashba interaction in proximity with s-wave superconductor, driven into topological phase by external magnetic field. Additionally, we take into account on-site Coulomb interactions inside the wire. The system is modelled by a tight binding Hamiltonian with Rashba hopping term and induced s-wave superconductivity. Calculations are performed utilizing recursive Green’s function method, and Coulomb interactions are treated selfconsistently within Hubbard I approximation. For the Hubbard levels residing within p-wave superconducting gap, particle–hole symmetric four-resonance structure develops in the density of states, apart from Majorana resonance. One pair of particle–hole symmetric resonances is created by the discrete II-Hubbard levels of the particular site, and the second pair of Hubbard sub-bands originates from recursive summation over the sites of the wire. Quantum interference between both types of pairs of states creates in-gap charge-conjugated Fano resonances with opposite asymmetry factors. We demonstrate that when quantum interference is dominated by two-particle tunneling, the Majorana resonance is strongly diminished, while it is not altered when single-particle tunneling dominates in interference process. We also discuss some consequences for experimental distinction of true Majorana states, and show that on-site Coulomb interactions support the appearance of topological phase.
Design and fabrication of networks for bacterial computing
Authors: van Delft Falco C M J M , Sudalaiyadum Perumal Ayyappasamy , van Langen-Suurling Anja , de Boer Charles , Kašpar Ondřej , Tokárová Viola , Dirne Frank W A , Nicolau Dan V
Published: August 2021

Non-deterministic polynomial (NP-) complete problems, whose number of possible solutions grows exponentially with the number of variables, require by necessity massively parallel computation. Because sequential computers, such as solid state-based ones, can solve only small instances of these problems within a reasonable time frame, parallel computation using motile biological agents in nano- and micro-scale networks has been proposed as an alternative computational paradigm. Previous work demonstrated that protein molecular motors-driven cytoskeletal filaments are able to solve a small instance of an NP complete problem, i.e. the subset sum problem, embedded in a network. Autonomously moving bacteria are interesting alternatives to these motor driven filaments for solving such problems, because they are easier to operate with, and have the possible advantage of biological cell division. Before scaling up to large computational networks, bacterial motility behaviour in various geometrical structures has to be characterised, the stochastic traffic splitting in the junctions of computation devices has to be optimized, and the computational error rates have to be minimized. In this work, test structures and junctions have been designed, fabricated, tested, and optimized, leading to specific design rules and fabrication flowcharts, resulting in correctly functioning bio-computation networks.
Measurements of Fast Transitions at a Reversible Pump Turbine Model in Closed Loop Test Rig
Authors: Junginger J , Kirschner O , Riedelbauch S
Published: August 2021

It is common practice to experimentally investigate the performance characteristics of hydraulic fluid machinery in power plants with steady-state operating points by scaled homologous model machines in closed-loop test rigs. In this case, the piping of the main water conduit from the power plant and the test rig plays a minor role. However, for studies of operating transient, e.g. load rejection, the influence of the weak compressibility of water in the pipes is considered by 1-D water hammer analyses. Due to differences in the main water conduit between the power plant and the test rig, the test rig is specifically controlled by new procedures to replicate the relevant conditions at the fluid machine in the test rig under similarity conditions.

The results of this newly developed method for specific control of the test rig for operating transients are presented and successfully validated on a closed-loop experimental system. In future, suitable instrumented model machines then allow the measurement of dynamic pressures or even strains in and on machine components in order to elaborate, as a goal, the influence of different operating transients on the service life of machine components. Furthermore, these experimental data can also be used to validate Computational Fluid Dynamics (CFD) and Finite Element Analyses (FEA) simulations.
Experimental Study of Break-off Frequency in Cavitation Disappearance Phenomenon on NACA16-012 Hydrofoil
Authors: Sugaya Koki , Ochiai Takaho , Okajima Junnosuke , Iga Yuka
Published: August 2021

Under the specific angle of attack on NACA16-012 hydrofoil, generated cavitation suddenly disappears even in the low cavitation number condition in which cavitation normally develops. This cavitation disappearance phenomenon was confirmed to be unique to NACA16-012 hydrofoil in our previous research. It was experimentally confirmed that cavitation disappearance phenomenon occurs in a transient cavitation condition where the sheet cavity is periodically broken off and the cloud cavity is released. In the previous study, it was predicted that there is the frequency band in which sheet/cloud cavitation cannot exist and cavitation disappearance phenomenon occurs. In this study, the break-off frequency of NACA16-012 hydrofoil was experimentally investigated and relationship between the break-off frequency and cavitation disappearance phenomenon was considered. The pressure fluctuation was measured with the pressure transducer downstream reagion and the dominant frequency was estimated by the frequency analysis. As the results, cavitation disappearance phenomenon was confirmed at angles of attack of 6° and 7°. There was the region increasing the break-off frequency according to decreasing of cavitation number at angles of attack 6° to 12°. It means that the break-off frequency of NACA16-012 hydrofoil has unusual characteristics. When the break-off frequency was expressed by the Strouhal number, it was found that the Strouhal number took each same value immediately just before and after cavitation disappearance phenomenon in decompression experiment. It was suggested that the break-off frequency was related to cavitation disappearance phenomenon.
Maximum Likelihood Identification of Cavitation Instabilities in Axial Inducers
Authors: Tumminia Matteo , Valentini Dario , Pace Giovanni , Hadavandi Ruzbeh , Torre Lucio , Pasini Angelo , d’Agostino Luca
Published: August 2021

The article illustrates the application of maximum likelihood estimation to the identification of cavitation instabilities in axial inducers from the unsteady pressure readings measured on the impeller casing. The typical triangular pressure distribution in the blade channels of the impeller is parametrized and modulated in time and space in order to theoretically reproduce the expected pressure generated by known forms of cavitation instabilities (cavitation auto-oscillations, n-lobed sub/super-synchronous rotating cavitation, higher-order surge/rotating cavitation modes). The Fourier spectra of the theoretical pressure so obtained in the rotating frame are transformed in the stationary frame and fitted by maximum likelihood estimation to the auto-correlation of the pressure measurements on the inducer casing. Each form of instability generates a characteristic spectral distribution of side bands in addition to its fundamental frequency. The identification makes use of this information for effective discrimination of simultaneous flow oscillations with significantly different intensities and partially overlapping frequencies. The method returns the estimates of the model parameters and their standard errors, allowing for both recognition of the forms of instabilities occurring in the inducer and assessment of the statistical significance of the results.
Relationship between statistical shift of the Fermi level and activation energy of conductivity in phase-change materials
Authors: Vorobyov Y V , Ermachikhin A V , Trusov E P
Published: August 2021

The non-Arrhenius behaviour of conductivity of phase-change materials is analysed in terms of the statistical shift of Fermi level. To show this connection, a simplified model for the density of states in a phase-change material is proposed to simulate the temperature dependence of the Fermi level. Comparison of the temperature dependence of conductivity of Ge2Sb2Te5 with the simulation results allowed estimating the position of defect levels in the bandgap.
Influence of polyaniline on the electrophysical properties of lead-free ceramics
Authors: Glazunova E V , Verbenko I A , Andryushin K P , Yurasov Yu I , Reznichenko L A
Published: August 2021

The effect of polyaniline additives on the dielectric and piezoelectric properties of a composite based on a multi-component system of sodium-potassium niobate was studied in the paper. The behavior of dielectric characteristics, electromechanical and piezoelectric properties of the system was studied. The critical concentration of polyaniline influencing the formation of an electromechanical connection between ferroactive inclusions and piezoelectric properties was determined.
The dependence of mechanical properties of Al-6101 alloy on geometry of the samples with a groove during tensile tests
Authors: Magomedova D K , Gunderov D V , Mavlutov A M
Published: August 2021

This paper presents data on the mechanical properties of 6101 aluminum alloy during tensile tests of cylindrical samples with a groove of various geometries. The values of ductility, yield, changes in geometry of the samples are provided. It was also shown that the parameters of ductility and strength depend on geometry of the sample for tensile tests.
Modeling for manufacturability of the design of parts with concentrators by the method of photoelasticity
Authors: Yagyaev Elmar , Shron Leonid , Meniuk Dmitriy
Published: August 2021

The article provides a methodology for the experimental determination of the concentration coefficients ασ and the gradients of the principal stresses. The effectiveness of the experimental method of photoelasticityis shown for studying the stress-strain state of parts of complex shape in the presence of stress concentrators, as well as for solving problems of brittle strength by methods of linear fracture mechanics.
Modern microbiological methods of phytosanitary monitoring
Authors: Nikolenko M V , Trigub V V , Enotkaeva O V
Published: August 2021

In this work, an express method is proposed, based on the registration of changes in the impedance of the nutrient medium, which occurs under the influence of the processes of growth and vital activity of microorganisms in the sample under study. The research was carried out on the analyzer “BioTrack 4250”. This device is highly productive, as it examined 21 samples simultaneously for several hours. For testing the indirect impedance technique, fodder, medicinal and weed plants were selected as objects of study. The sanitary condition of the samples was assessed by the total mesophyll aerobic and optional-anaerobic microorganisms (QMA&OAMO), sanitary-indicative bacteria of the E. coli group, and the number of yeast fungi. It was proved that plants collected in the central part of the city of Tyumen with a high population density had high QMA&OAMO indices and high indicators of contamination with Candida sp. On the contrary, fodder plants growing in the Tyumen region were characterized by high indices of sanitary-indicative microorganisms, which indicated an increased risk of feed contamination. Thus, in contrast to the classical methods, the proposed method allows obtaining objective results, shortening the research time, reducing labor costs, and significantly reducing the cost of analysis.
Nanostructured wear-resistant coating for the composite turning inserts
Authors: Litvinov Artem E , Yu Buz’ko Vladimir , Ivanin Sergei N
Published: August 2021

The article presents the results of study of microstructural and strength properties of developed nanostructured wear-resistant high-hardness coating with high strength characteristics, resistance to shock and vibration loads on the surface of cutting inserts for instrumental and high-speed steel turning treatment. The specificity of the turning operating conditions of the composite cutting tool inserts shows that the cutting inserts working surface should have such characteristics as high hardness, strengths, increased vibration resistance, resistance dynamic loads and thermal shock, as well as increased wear resistance. Therefore, one of the ways to solve this problem proposed in the report is applying a wear-resistant hard oxide phase nanostructured coating on the surface of the cutting edge of the composite cutting inserts. Technological modes were selected for the wear-resistant hard protective coating which provides high microhardness due to the nanostructure by magnetron sputtering deposition of the developed compositions that have high adhesion to substrates made of composite cutting turning inserts. The results are shown on the example of high-speed turning of 30KhGSA by using composite turning inserts with developed nanostructured wear-resistant hard protective coating.
Plasma-chemical deposition of gallium oxide layers by oxidation of gallium in the hydrogen-oxygen mixture
Authors: Mochalov L A , Logunov A A , Kudryashov M A
Published: August 2021

Gallium oxide is an ultra wide band gap (the width of the band gap is 4.85 eV) transparent semiconducting oxide, that nowadays attracts much attention of scientists and manufacturers. However, the main obstacle, preventing from its massive commercial implementation, is the lack of technological methods to its production; it is supposed to be cheap, reproducible, and scalable. In this work we are developing a novel plasma-chemical method of Ga2O3 thin films’ synthesis; according to this method only high-purity elemental gallium was used as the source of gallium delivered by the hydrogen flow into the plasma discharge zone, where the interaction with oxygen took place. The properties of the solid phase obtained in the conditions of heteroepitaxial growth were studied depending on the experimental parameters.
Justification of impregnation modes for wood
Authors: Gazizov A M , Samosenko E G , Popova E V
Published: August 2021

One of the most significant disadvantages of wood materials is increased combustibility. Therefore, the problem of reducing the combustibility of wood materials is relevant. The article describes an experimental study of impregnation of wood using biopiren MIG-09, which is a hybrid composition on a salt basis with the addition of functional substances of non-salt nature, at different temperature regimes. Two stages of the study were chosen for the experiment. The optimum temperature regimes for different methods of applying the composition to increase the fire resistance of wood were established experimentally. Also fire tests were carried out to analyze the degree of penetration of the solution.
Non-autoclave ash-filled porous concrete for bearing and enclosing structures
Authors: Belov V V , Kuliaev P V
Published: August 2021

Non-autoclaved ash-porous concrete (NAAC), which is enlightened in the article facilitates the reduction of the cost of construction of large-space engineering structures and multi-storey buildings. It is possible due to eliminating the use of expensive porous aggregates, which involves using the porization effect of the concrete mixture in the manufacture of such structures, as well as using of waste from local industry. It also reveals the advantages of using cellular concrete of non-autoclaved hardening, which has a low energy consumption. Such material is showed to be of use in production of load-bearing and enclosing reinforced concrete structures.
New polymorphic varieties of graphyne formed on the basis of 5-7b graphene: Ab initio calculations
Authors: Mavrinskii V V , Belenkov E A
Published: August 2021

The crystal and electronic structure of 16 new polymorphic varieties of sp+sp2 graphyne layers was calculated by the density functional theory method in the gradient approximation. The primary structure of the graphyne layers was constructed by replacing the interatomic bonds in the graphene layers 5-7b with carbyne chain fragments. Ab initio calculations have shown that out of 29 modeled structures only sixteen are stable: 14 β-type layers and one α- and γ-type layer each. During optimization 13 graphyne layers were transformed into graphene layers or into graphyne layers with a smaller relative number of sp-hybridized atoms. The electronic properties of most of the new graphyne layers are metallic, since the density of electronic states at the Fermi energy level for them is different from zero. There are forbidden zones in the electronic structure of the seven layers, but their value is small and varies from 0.05 to 0.20 eV.
Comparison of sequential and circular scanning thermal fields and their influence on microstructure of Alnico alloy produced by laser powder bed fusion
Authors: Kuznetsov P A , Shakirov I V , Mozhayko A A , Zhukov A S , Bobyr V V
Published: August 2021

Residual stress create deformations and stress in additive structures that lead to geometry deviations of created elements of 3D models and defects as pores and cracks that occur in construction process. Our work rests upon theoretical and experimental approach to the study. The main objective is to compare thermal fields with the microstructure of samples and to establish relationship between laser powder bed fusion (LPBF) modes and the structure of the samples to be created. 3D finite element method (FEM) is used for macroscopic modeling to assess the effect of thermal fields on the microstructure of Alnico alloy. Comparison of the temperature fields with the microstructure of samples made by LPBF showed that the type of scanning (both bidirectional and circular) had a strong influence on the distribution of the thermal fields and, accordingly, on the microstructure of the samples made by LPBF.
The Simulative Optimization of Aerosol Micro Atomizer for Pulmonary Delivery Device
Authors: Zhang Zhen , Yang Wenhui , Chen Jun , Liu Yujie , Wang Xudong
Published: August 2021

The present study investigated the design optimization of aerosol micro atomizer for liquid pulmonary device. Pulmonary delivery device with a micro atomizer at the tip is commonly used to penetrate into a small animal’s trachea, and directly quantitatively spray the infected dosing aerosol samples to animal’s lung. In order for no damage to animal’s trachea, a long capillary with a diameter of 0.5-0.6 mm is used for flow diversion. Therefore, the swirl atomizer size of the head is required to be adequately tiny with uniformity and penetration of aerosol spray. Due to structural limitation without adequate rotational space, it is highly challenging to provide the fine atomization with high quality. Therefore, based on the simulation analysis in Simspray software, the optimization design of the micro atomizer is conducted, aiming to improve the atomization quality with a certain spray angle. Parametric study on swirl atomizer structure, including swirl pitch, nozzle diameter and size of swirl channel, realized an excellent combination of parameters to meet requirement of fine spray. The experiment testifies that the 3-5μm aerodynamic diameter of droplets in spray is available.
The Influence of Dusty Size Distribution Model on Propagation of Electromagnetic Waves in Inhomogeneous Plasma Sheath
Authors: Zhang Jie , Zhang Guodong , Zhao Shanchao , Han Bing
Published: August 2021

In this paper, a linear distribution model, a double exponential distribution model and a hyperbolic number distribution model are developed, and the effect of dust particle size distribution on its attenuation coefficient is considered. On this basis, the transmission characteristics of electromagnetic waves in dusty plasma under different electron density distribution models are investigated. The attenuation coefficients of electromagnetic waves are derived in detail using analytical methods, and the effects of electromagnetic wave frequency, particle collision frequency and dust particle density on the transmission characteristics of electromagnetic waves are discussed. The results show that the choice of terahertz wave as the carrier wave and the appropriate change of particle collision frequency can improve the attenuation of electromagnetic waves. In summary, the relevant research can provide some theoretical references for propagation science.
A Stochastic Volatility Model with Mean-reverting Volatility Risk Premium
Authors: Peng Ke , Xun Ziying , Hu Mingzhu
Published: August 2021

The volatility risk premium (VRP) has long been the core issue in option pricing and risk management. The VRP is usually defined as a linear function of volatility which ignores the time-varying property of VRP and limits the degree of freedom of the model. In this paper, we adopt a CIR process in the stochastic volatility model (VRP-CIR-SV) to incorporate the mean-reverting and time-varying properties of VRP. We show that the decomposition of VRP is consistent to investor’s behaviour. Our Monte Carlo simulation results show that, compared with the traditional linear VRP model, the VRP-CIR-SV model can better depict the rich shapes of implied volatility curve. Our paper innovatively models the time-varying VRP with mean-reverting property, which may provide new thoughts for VRP estimation.
Simulation Design and Optimization of UV-LED Water Purification System Based on Fluid Dynamics and Radiometry
Authors: Liu Rui , Zhou Chao , Lu Rucong , Zhang Jiang
Published: August 2021

In this paper, we established the flow field and radiation intensity distribution models of water purification equipment based on computational fluid dynamics (CFD) technology and radiometric principles. From geometric shape to hydraulic state and radiation intensity distribution, we fully simulated the real scene of the Ultraviolet LED (UV-LED) water purification system, and provided the reliable data for the UV-LED in the water purification field. Compared with mercury lamp, UV-LEDs have a more flexible layout to produce a variety of radiation intensity distributions. UV dose (the product of radiation intensity over time) is an important indicator. We used a discrete phase model (DPM) to track the path of microbial particles, and found that the residence time of microorganisms in different parts of the model was different. By optimizing the UV-LED layout, the radiation intensity was increased in the sites where the microbes resided longer. The results show that we can improve the efficiency of the water purification equipment by simply adjusting the UV-LED layout without increasing the power, and make the UV dose achieves the national standard.
The Collaborative Combat of Heterogeneous Multi-UAVs Based on MARL
Authors: Fang Jiayong , Han Yun , Zhou Zhongliang , Chen Shitao , Sheng Sheng
Published: August 2021

In the course of collaborative combat of multi-UAVs, there appear so many unpredictable fluctuations in the combat situation, and the mission assignment and decisionmaking of the combat are sequential and game-oriented, rendering it hard to build its dynamic and accurate model of operational missions. This paper breaks through the traditional research idea of mission modeling and optimization solution of collaborative operations of UAVs, and applies multi-agent reinforcement learning to the decision-making of multi-UAV collaborative combat, builds a verification environment of collaborative air-to-ground penetration and attacks of heterogeneous UAVs by designing MARL algorithm architecture, situation model, decision model and reward and punishment model, realizes the autonomous evolutionary learning of mission assignment and decision-making, and finally analyzes and evaluates the effectiveness and robustness of different MARL algorithms.
Electrical Characteristics of Floating-body and Body-contacted Silicon-on-insulator n-channel Transistor by TCAD Simulation
Authors: Shi Zhaolong
Published: August 2021

This work investigates the electrical characteristics of floating-body and body-contacted SOI devices with Synopsys Sentaurus TCAD simulations. Short channel effects, subthreshold slope, transconductance, DIBL, on and off current are compared and analyzed for floating-body and body-contacted SOI devices, which is useful for device design and optimization. At the same time, the results of TCAD numerical simulation are used to compare the floating body effect characteristics of the two kinds of devices. From the results, the performance of body-contacted SOI devices is better. All the figures in this paper are obtained from TCAD simulation data and results based on 2D device simulation. Circuit and 3D simulations are beyond the scope of this paper, which will be investigate in future work.
Simulation Design and Analysis of the Three-dimensional Shape Testing Device for Functional Microfilaments
Authors: Liu Shan , Yin Junqing , Qin Shujuan , Chen Yongdang , Gu Jinyu
Published: August 2021

In order to study the micromechanical properties of functional microwires in three-dimensional space morphology, a performance testing device for functional microwires in three-dimensional morphology combined load mode was designed. First, the microwire material is introduced into the three-dimensional weaving process, and the cubic B-spline function curve is used to fit the shape of the three-dimensional microwire, and then the spatial configuration of the microwire is constructed. Secondly, based on the three-dimensional morphology of the microwire, the function and principle of the microwire in the compound loading mode are analyzed, and a three-dimensional testing device for the microwire is designed. Finally, the key components of the designed device were analyzed through simulation, and the key components of the test device were all within their yield limits, which verified the rationality of the test device.
Primitive Knowledge Graph Construction Base on Eventelement Driven
Authors: Wang Nana , Guan Zhuoyun , Guo Yu
Published: August 2021

Knowledge graph is a popular research field in recent years. Starting from analyzing the dynamic needs and feasible ways of knowledge graph, A new idea of using matter elements as entities in the knowledge graph is proposed, and a dynamic evolution mechanism of knowledge graph driven by matter elements is established. Using the primitive theory to construct the framework structure of the primitive knowledge map.