bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the Jouamaa groundwater quality using Physico-chemical water analysis and Geographic Information System
Authors: Azzirgue El Mustapha , Salmoun Farida , Cherif El Khalil , Mejjad Nezha
Published: October 2021

The present study seeks to determine the water quality of wells located in the Jouamaa Hakama commune (Northern Morocco). In this order, nine water samples were collected from wells used by local residents during two sampling campaigns in December 2016 and June 2017. The samples collection was followed by the laboratory analysis for measuring the water Physico-chemical characteristics including pH, temperature (T°), Conductivity (Cond), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD5), Dissolved Oxygen (DO), Suspended Matter (SM), Turbidity, Nitrite, Nitrate, Ammonium and Phosphate. Also, spatial data analysis has been done using Geographic Information System (GIS) by ArcGis software to show a statics map with significant water quality information for the studied wells. The spatial analysis showed higher concentrations exceed the Moroccan groundwater quality values in P6 and P8 for the EC in 2016 and 2017. Similarly, for the turbidity, higher values recorded in P8, while the DO concentration was significant in P6, P8 and P9, other sampling points indicate values close and inferior to water quality standards. P3, P4, and P8 showed higher Ammonium, Nitrite and phosphate values during the summer period of 2017. The analysis results shed light on contamination factors: domestic activities and agricultural activities in urban zones (Hakama and Jouamaa). However, the use of these waters could pose a risk to the health of human and animals. Similarly, The GIS is a practical, innovative and effective tool for the Jouamaa groundwater quality diagnostic and could help decision-makers establish solutions.
Technological Approaches to Thermomechanical Processing of Quartz Glass Parts
Authors: Basharova Anna , Schenyatskiy Aleksey , Kotelnikov Mikhail
Published: October 2021

The article discusses technological approaches applied to the processing of products made of quartz glass and used as components of gyroscopes and navigation devices. The developed block diagram of technological processes gives an idea of the life cycle of manufacturing a sensitive element - a gyroscope resonator, as well as input and output parameters at each of the manufacturing processes. Simulation of thermomechanical processing of samples in CAE Ansys with specified parameters of surface roughness gives an idea of the course of the process and technological modes. The selected temperature regimes make it possible to design a thermomechanical treatment process in order to carry out a practical study of the process.
Improving the Accuracy and Quality of the Surface Layer of Products by Local Magnetic Pulse Processing
Authors: Gritsyuk Vasily , Smolentsev Evgeny , Krokhin Dmitriy , Pechagin Aleksandr
Published: October 2021

This article discusses development of technological modes and the process of stabilizing the properties of surface layers of large-sized parts, ensuring accuracy and stability of the products’ shape during their manufacture and operation, while using combined processing methods that replace costly heat treatment at mechanical engineering enterprises.
Effect of Modifiers Introduced into Cold Phosphating Solutions on the Physical and Mechanical Properties of the Formed Phosphate Films
Authors: Konovalova Viktoriya
Published: October 2021

This work is devoted to the study of the physical-mechanical and protective properties of modified phosphate coatings obtained on steel by cold method. Modifiers introduced into phosphating solutions are buffer additives, stabilize the phosphating process, allow the deposition of coatings at low temperatures, increase the number of active centers on the metal surface, resulting in fine-crystalline uniform coatings of small thickness. It was found that the corrosion rate of modified phosphate films is 2 times less than that of coatings obtained by the traditional method. When the temperature rises above 100 °C, the corrosion resistance of phosphate coatings decreases, and the satisfactory protective properties of the modified films are preserved when heated to 200 °C. Modified phosphate coatings have a high adhesion strength to the metal due to their small thickness. However, thin phosphate coatings have low wear resistance and medium electrical insulation properties.
The Study of the Flat Grinding Process of Workpieces of Composite Materials
Authors: Sapunov Valeriy , Vetkasov Nikolai , Varlamov Sergey
Published: October 2021

The paper shows the results of the carried out examination of the grit of the processed surface and the intensiveness of the flat grinding of workpieces of composite materials. The processing has been carried out using of a special grinding tool with anti-frictional fillers produced in accordance with the microwave technology. The grit and components of grinding forces of workpieces of aluminomatrix composite materials with various carbon contents have been determined.
Optimization of Deposited Coating Chemical Composition during Operation in Urea Medium
Authors: Nazarko Aleksandr , Plomodyalo Roman
Published: October 2021

The article deals with the problem of optimization of the chemical composition of the deposited metal operating in the urea melt. To improve the technological properties and increase the resistance of the deposited metal against intergranular corrosion, manganese (0.5-1.8 pts. wt.) and niobium (0.3-1.8 pts. wt.) were introduced. The chromium content was varied in the range of 20-30 pts. wt., nickel – 3-8 pts. wt.
Study of Chromium Effect on Structure and Wear-Resisting Properties of Complex Alloyed Brass
Authors: Ivkin Maksim O. , Mysik Raisa K. , Brusnicyn Sergej V. , Sulicin Andrej V.
Published: October 2021

The microstructure of CuZnMnAlSiNiCr complex alloyed brass was examined. The effect of various chromium content in the range from 0.00 to 0.33 wt.% on the composition and morphology of intermetallic compounds was established, and the amount of chromium-based intermetallic compounds was estimated. Microhardness of intermetallic compounds of various morphology was determined. The effect of chromium content on wear rate of brass samples was estimated. The range of chromium content at which samples wear rate is minimal was estimated.
Expansive Concretes for Shotcrete in Tunnel Construction
Authors: Kharchenko Igor , Panchenko Alexander , Kharchenko Aleksey
Published: October 2021

This paper presents the results of investigation of properties of fine-grained concrete on expansive cement for fiber-reinforced shotcretes used for metro tunneling. Basic factors affecting material expansion after mixing with water are described. The influence of expansive components on the values of strength indices and volumetric deformations of shotcrete is studied. Improvement of process, physical and mechanical, and operational characteristics of obtained shotcrete is proven.
Anodizing under conditions of oxygen activation of the inter-electrode gap
Authors: Kolenchin Nikolay , Denisenko Denis
Published: October 2021

Structured alumina is currently used in a wide range of applications. Interest in a surface with a wear-resistant coating motivates creation of methods for high-speed oxidation with an increase in the thickness and hardness of the layer, with obligatory observance of environmental parameters and a decrease in the energy intensity of production. Considering the activity of aluminum towards oxygen, a very important aspect is the search for conditions to increase the natural oxide film to the level of functional significance. The generally accepted scheme of classical anodizing represents a closed system of an electrolytic cell, inside which the elements are activated in the interelectrode gap to the state of ionic excitation under the action of an electric field. The efficiency of interaction depends on the medium’s nature and variability of the volt-ampere parameters. This work proposes a different mechanism for intensifying the process. Oxygen is activated outside the electrolytic cell and in the allotropic state, in the form of ozone, is transmitted into the interelectrode gap. The phase composition, structure, thickness, and microhardness are investigated. The aim of the research is to establish the effect of ozone on the oxidation process.
Features of Constructing Recrystallization Curves of the 2nd and 3rd Types for High-Alloy Alloys of Various Structural Classes VZH159 and 14Cr17Ni2
Authors: Galkin V.V. , Yavtushenko P. M. , Generalov A.A. , Fomichev A. S. , Bazhenov E.O.
Published: October 2021

The features of methods for constructing recrystallization curves of the second and third kind and the dependence “average grain size (area) - strain intensity – temperature” are given. For alloys of various structural classes VZH159 and 14Cr17Ni2 using the above methods, a recrystallization curve and the recrystallization dependence for a temperature of 1100℃ are constructed. The advantages and disadvantages of the above methods are considered.
The development of the method for identifying the hardening curves of materials based on the results of torsion tests of notched specimens
Authors: Erpalov Mikhail , Panin Evgeny
Published: October 2021

The article is devoted to studying the rheological properties of metals and alloys in a cold state. The method is proposed to identify the hardening curve of a material based on torsion tests of round specimens with a notch. Determining the hardening curve is based on measuring the coordinates of points on the surface of the specimen after testing and determining the corresponding value of the torque. Based on these values the coefficients in an equation for the stress-strain dependence can be determined by minimizing the derived functional. The paper proposes the algorithm for the numerical implementation of the new identification method. The results of the computer simulation confirmed its effectiveness.
Mathematical Model of the Process of Pallet Movement Along the Magnetic Type Centrifugal Brake Roller
Authors: Sharifullin Ildar , Nosko Andrey , Safronov Yevgeniy
Published: October 2021

One of the main elements of safe operation of gravity flow racks used in pallet racks is a brake roller. The most promising design is a centrifugal brake roller of magnetic (eddy current) type. The principle of operation of such rollers is based on the laws of electromagnetic induction and involves the deceleration of a conductor moving in a magnetic field, due to the interaction of eddy currents (or Foucault currents) arising in the volume of the conductor, with an external magnetic field. The mathematical model of the process of pallet movement along a centrifugal brake roller of magnetic type is developed in the article. The equation of the speed of movement of the pallet along the centrifugal brake roller of magnetic type is obtained. Comparative analysis of the speed of movement of a pallet along centrifugal and disc brake rollers of magnetic type is carried out.
Analysis of Designs of Distribution Systems of Grain Pneumatic Seeders
Authors: Bogus Azamat E , Stanin Vladislav , Vyshebabina Alina
Published: October 2021

The design of distribution systems of modern pneumatic grain seeders is considered. Classifications of central metering systems and distribution systems have been compiled. The advantages and disadvantages of distribution systems of different designs are described.
Experimental Observation of a Regression Dependence for Hydrodynamic Performance of the Regular Packing
Authors: Balchugov Alexey , Badenikov Artem
Published: October 2021

The investigational studies of regression dependence of the new efficient regular packing bed’s flow friction on gas velocity and liquid spray rate has been carried out. The tests were made by the procedure of a complete two-factor experiment. On account of experiment design matrix, there are four tests to be made to determine the regression dependence. It is found that the packing bed’s flow friction builds up along with increase of superficial gas velocity and liquid spray rate. The regression dependence that puts packing bed’s flow friction in touch with superficial gas velocity and liquid spray rate is procured. The specific dependence is valid for air velocity 1.21-3.12 m/sec and liquid spray rate 0.0080-0.0304 m3/(m2 sec). The conclusion on significance of regression dependencies has been made in terms of Student’s t-test. The sufficiency of regression equation has been inspected via the Fisher’s criterion. The resulting regression equation can be utilized in the design and engineering process of absorbers with the shock-spray packing.
Design Improvement of Cutting Part in Tunneling Shield
Authors: Letopolsky Anton , Korchagin Pavel , Teterina Irina
Published: October 2021

The article presents a variant for improving the design of a working body of a tunneling shield, its cutting part to be more precise. The working body of the tunneling shield has been improved with the changes in the design of a rotor working surface. The theoretical studies aimed at determining the strength characteristics of the proposed rotor design have been carried out. The proposed rotor model has been visualized with the use of the T-Flex CAD software. On the basis of the results obtained in the course of the theoretical research, a comparative analysis of the strength characteristics of the main and improved model of the cutting working body of the tunneling shield have been made. The studies carried out at T-Flex CAD confirmed the working capacity of the improved design of the tunneling shield working body. The strength of the rotor has been determined as a result of the studies carried out. The maximum values of the displacement module is 2.875E-05 m, the equivalent stresses are 29.47 MPa, a reserve coefficient on equivalent stresses is 9.446E 06.
Mathematical Model of Influence of Geometric Parameters on Wave Gear Teeth Wear
Authors: Lyuminarskiy I. Ye. , Lyuminarskiy S.Ye. , Lyuminarskaya Ye. S.
Published: October 2021

The object of the research is a wave gear with a cam wave generator. One of the requirements for wave gears is to increase the wear resistance of the teeth flanks. A mathematical model that makes it possible to assess the influence of the geometrical parameters of the gear on the teeth wear is proposed in this work. To assess the specified effect, the maximum and average wear coefficients are introduced. To calculate these coefficients, a spatial mathematical model of a wave gear is used, taking into account the volumetric and contact deformations of gear wheels and a flexible bearing. Using the developed technique, the dependences of the wear coefficients on the radial deformation and the length of the flexible gear were obtained. The given dependences increase the knowledge concerning the influence of geometric parameters on the wave gear teeth wear.
Machine-Building Enterprise Work Improvement Based on Application of the Process Approach
Authors: Kalinin Evgenii V. , Kalinina Ludmila L. , Metelev Dmitrii A.
Published: October 2021

Any modern machine-building enterprise is a complex system consisting of many organizational elements with clearly defined functions, boundaries and resources. The size of these resources determines the planned productivity of the enterprise. At the same time, an enterprise is a social system that has non-linear properties, since the human factor is involved. Therefore, situations are possible where even small beneficial changes in the nature of the interaction in the production system can cause a significant increase in productivity. However, situations are also possible when large transformations that consume significant resources do not lead to desired achievements or even worsen the existing state. This article discusses the application of process-oriented thinking in the practical work of an enterprise at all its levels.
Recommendations on Diagnostics of Support Condition of High-Speed Spindle Units
Authors: Gasparov Eric , Gasparova Lana , Markosyan Gevorg
Published: October 2021

In the course of the study, amplitude-frequency characteristics of the responses of vibrational acceleration of the spindle unit were obtained experimentally with a short-term impact of a force directly on its spindle. By analyzing the frequency composition of amplitude spectra, the peaks of natural frequencies of the spindle unit were determined at various values of the preload, and, accordingly, the operating modes of the spindle unit were selected, which would reduce its vibration activity and increase processing accuracy.
Nonlinear Dynamics of Heavy Structures
Authors: Izvekov Yury , Tulupov Oleg , Kinzina Irina , Kanel-Belov Alexey
Published: October 2021

At the moment, not enough attention is paid to different aspects of nonlinear dynamics for heavy structures. In this article we attempt to create a mathematical model for finding a frame (field) with predictable dynamic pattern of load-carrying capability for a heavy structure based оn the parameters of its reliable (failure-free, low-risk) operation. It is difficult to find a solution for this problem now but the following algorithm can be applied. Small dimension projection is first obtained for orthonormal vectors determining the structural load-carrying capability. Then we use available methods to find a field where any relationship (functional, logical) can be obtained between the rules (wild cards) and the load-carrying capability displayed by a heavy structure. This article carries on the cycle of activities on structural risk analysis involving heavy structures. Numerical and calculated data are based on previous studies. The analysis is performed on a metallurgical overhead crane. The obtained findings are used for adopting various engineering solutions at different stages of heavy structure operation.
Systematization of the Mineral Raw Material Waste Recycling Process
Authors: Bardovsky Anatoly , Basyrov Ilnur , Valeeva Liliya
Published: October 2021

The paper considers a system for optimizing the recycling process of mineral raw material waste in terms of the target function, which takes into account economic, technological, and environmental criteria. We have suggested a structural model of the production process of mineral raw material recycling using cost flows. Based on the analysis of this model, we concluded on the need to develop new methods for assessing and choosing the parameters of the equipment used, including specific performance criteria to assess the degree of sophistication of the systems under study.
Monad Theory of Structural Synthesis of Mechanisms
Authors: Kuznetsov Sergey
Published: October 2021

Structural synthesis creates a structural scheme according to the given structural characteristics - the degree of abnormality of the structure S and the degree of its irrationality s. Structural scheme is created at the first stage of synthesis, containing only rotational kinematic pairs and corresponds to a given degree of abnormality, which is ensured by the ratio of structural units – plus monads, minus monads and null monads. At the second stage, the independence of structural characteristics makes it possible to bring the obtained scheme to a given degree of irrationality by downgrading the class of kinematic pairs. The proposed algorithm makes it possible to synthesize structural schemes of both normal structure and adaptive (with redundant motions), as well as indifferent (with redundant links). Monadic approach to structure research allows to formalize the structural features of the circuit and to create a knowledge base for automated design of structural circuits with given structural properties.
System Capability Estimation for Various Information Operations Used
Authors: Geyda Alexander
Published: October 2021

The article considers system capability (or – system potential) estimation regarding different kinds of information operations use. Information operations classification suggested. System capability is introduced in the article as property to research teleological (goal- and effects-related) aspects of information technology. Such aspects are studied analytically, with predictive and prescriptive mathematical models and methods. Researchers can apply system capability to dynamic capability, organizational capability investigation regarding information technology, learning technology, and innovation technologies use. Example of system capability estimation considered.
Electromechanical Transmission of Skid Steer Loader
Authors: Khomichev Alexey , Volkov Alexandr
Published: October 2021

The article analyzes the power train components of skid steer loaders. The choice of the scheme and the design of the transmission units of the loader with a traction electric drive is substantiated. The results of calculating the traction characteristic of the straight-line movement of the loader taking into account different values of the coefficient of resistance to movement are presented.
Theoretical Studies of Design Parameters of Machine Elements for Surface Planting of Rice
Authors: Masienko Ivan , Shevchenko Sergey , Vasilenko Artem
Published: October 2021

The paper presents the definition of the main parameters and operating modes of spreading centrifugal devices of technical means when using them in the surface planting technology. It has been determined analytically and experimentally that under the existing operating modes of centrifugal apparatus, in order to reduce reflection, grooved blades should be used, the upper planes of which are tilted from the horizontal position by an angle of 5-10 °, the angle of the blades should be ≤15 °. According to the results of theoretical and experimental studies, a prototype was made, the productivity of which when sowing rice in comparison with serial machines increased by 1.5 times with an uneven distribution over the working width not exceeding 15%.
Fuzzy Fault Detection for Permanent Magnet Synchronous Motor
Authors: Romanov Alexander
Published: October 2021

In the transition to automated and automatic manufacturing an urgent problem is to increase the reliability of mobile robots (MR) and their drives, creation of devices to monitor the technical characteristics of MR, diagnose and predict the remaining resource. Inspite of the high relevance of the diagnosing MR drives problem, there are no generally accepted methodology for diagnosing MR drives, criteria for selecting methods, parameters and volumes of diagnostics at present. An unsolved problem, related to the diagnosis of MR drives and the prediction of their residual life remains, is the development of methods that allow to carry out of automatic complex multiparametric diagnostics and prediction of the residual life using artificial intelligence methods. Effective fault detection and diagnosis can improve the reliability of the MR drive and avoid costly maintenance. In this paper a fault detection scheme for synchronous motors with permanent magnets based on a fuzzy system is proposed. The sequence current components (positive and negative sequence currents) are used as fault indicators and are set as input to the fuzzy fault detector. The expediency of the proposed scheme for determining of various types of faults for a synchronous motor with permanent magnets under various operating conditions is simulated using the SimInTech software.
Separation of Fine Particles from Gas in Paint-Spraying Booths
Authors: Bikkulov Rustem Ya. , Dmitriev Andrey V. , Zinurov Vadim E. , Badretdinova Guzel R.
Published: October 2021

Nowadays, at production facilities with paint-spraying booths that use paint and varnish materials to cover the surfaces of product, the problem of gas flow contamination with finely dispersed solid particles of dust and rubbish, which negatively affect the quality of products, is increasingly being raised. In order to minimize the content of solid particles in the gas flow, coarse and fine filters are installed in the paint-spraying booths, which prevent dust particles from entering the surface of products. However, the existing purification devices have a number of disadvantages that affect the efficiency of collecting finely dispersed particles from the gas flow with a size of 0.5-5 microns. The authors of article developed a square separator to increase the efficiency of collecting finely dispersed particles from gas flows in the paint-spraying booths. The installation of proposed separation device in the paint-spraying booths affects not only the quality of collecting solid particles, but also increases the service life of fine and coarse filters In the course of numerical studies, the results of impact of structural and technological parameters, namely, the impact of inlet rate and scale of separation device on the efficiency of collecting solid particles from the gas flow, were obtained.
Selection of Transmission and Electrical Motor Parts for ATVs
Authors: Evseev Kirill , Dyakov Aleksey , Goncharov Roman , Chutkov Konstantin
Published: October 2021

The article presents the results of calculations to justify the choice of transmission components and traction electric drive. The choice of the parameters of the gearing of the transfer case and differential has been substantiated. The choice of bearings is substantiated from the conditions of ensuring the given resource and strength for the transfer case and main gear.
Formation of Moments Influence Matrix in Frame Based on Graph of its Design Scheme
Authors: Monakhov V.А. , Shein А.I.
Published: October 2021

A procedure is proposed for the automated construction of the bending moments influence matrix in the frame based on the graph of its discrete model. Forming the incidence matrix of the graph characterizing the topological structure of the design scheme of the frame, through matrix transformations of the displacement vectors, at the transition from local coordinate systems to a global system, it is possible to establish the relationship between the nodal displacements and the displacement increments of individual sections in the direction of the axis of the segment and perpendicular to it. The composition of only three initial matrices of the frame structure, the incidence matrix of the graph, the node coordinate matrix and the matrix of the frame model internal rigidity, solves the problem of automatic formation of the bending moments influence matrix with the help of a PC. The procedure proposed for the construction of the influence matrix, makes it possible to find the forces in the frame structure caused by external load, in the matrix form.
Technical Solution for Complex Layer-by-Layer Tillage with Soil Formation Turnover
Authors: Belousov Sergey , Tsymbal Alexander
Published: October 2021

The paper deals with the issues of mechanization of main till-age with the soil formation turnover, the problems of traction resistance and possible solutions. The article has an analytical character, the analysis of ways and means of a possible solution to the problem of reducing traction resistance is given based on the results of studying the works of leading scientists in this direction. A technical solution for improving the design of the dump plow body is proposed. The technical process of working with the use of proposed working bodies is also justified. In conclusion, the main results achieved so far are presented.
Die Folgen des Krankenhauszukunftsgesetzes: Das KHZG – Fluch und Segen zugleich
Authors: Bertsch Isabel
Published: October 2021

Viele Krankenhäuser arbeiten mit Hochdruck an den Fördermittelanträgen des Krankenhaus­zukunfts­gesetzes (KHZG) oder befinden sich bereits mitten in der Umsetzung notwendiger Projekte. Die indirekten und langfristigen Folgen ökonomischer Verpflichtungen sind erheblich.
Research on the FM control for hydraulic wind turbine based on virtual inertia compensation control method
Authors: Chen Lijuan , Ge Jie , Gao Wei , Zheng Pengfei , Ai Chao , Li Jingbin , Zhang Wenqiang
Published: October 2021

Wind has been admitted as one of the most promising renewable energy resources in multinational regionalization policies. However, the intermittent wind energy volatility and the weak coupling between traditional wind generators and the power grid all influence the electrical grid frequency stability. The hydrostatic transmission wind turbine (HWT) is taken as the research object, and the hydraulic energy storage system (HESS) is introduced into HWT to improve the frequency regulation capability. First, the mathematical models of rotor, hydraulic power main transmission system, and the excitation synchronous generator are established. Then, the HWT frequency modulation characteristics are analyzed under different amplitude of load frequency fluctuation. In view of the HWT limited frequency modulation capability, the frequency modulation control strategy based on virtual inertia compensation is proposed with the HESS. Under the condition of maximum power point tracking, the effectiveness is verified. The simulation and experimental results show that the control strategy has a good control effect, and the HESS dynamic response characteristic satisfies the wind power–frequency regulation. The research results will be helpful to make wind power become grid-friendly power and solve the problem of electrical grid low frequency stability.
Analytical modeling of the evolution of the nonlinearity parameter of sensitized stainless steel
Authors: Fuchs Brian , Qu Jianmin , Kim Jin-Yeon , Unocic Kinga A. , Guo Qianying , Ramuhalli Pradeep , Jacobs Laurence J.
Published: October 2021

Austenitic stainless steels are subject to the precipitation of chromium carbides (M23C6) during exposure to high temperatures, causing these alloys to be susceptible to intergranular corrosion due to chromium depletion along grain boundaries. The acoustic nonlinearity parameter, β, shows sensitivity to the formation of carbides in these alloys. The Thermo-Calc TC-PRISMA module was used to model the nucleation and growth of grain boundary M23C6 carbides. The model was verified with scanning transmission electron microscopy analysis that allowed measurements of the grain boundary precipitates. The paper introduces a reduced-order model of the acoustic nonlinearity based on the formation of misfit dislocations at the interface of the grain boundary precipitate and matrix to explain the change in β during isothermal aging. A direct relationship between the radius of the M23C6 grain boundary carbides and β was observed and verified with nonlinear ultrasound measurements on 304L and 316L stainless steels.
Dynamical invariants and inverse period-doubling cascades in multi-delay systems
Authors: Kamyar Tavakoli S. , Longtin André
Published: October 2021

We investigate transitions to simple dynamics in first-order nonlinear differential equations with multiple delays. With a proper choice of parameters, a single delay can destabilize a fixed point. In contrast, multiple delays can both destabilize fixed points and promote high-dimensional chaos but also induce stabilization onto simpler dynamics. We show that the dynamics of these systems depend on the precise distribution of the delays. Narrow spacing between individual delays induces chaotic behavior, while a lower density of delays enables stable periodic or fixed point behavior. As the dynamics become simpler, the number of unstable roots of the characteristic equation around the fixed point decreases. In fact, the behavior of these roots exhibits an astonishing parallel with that of the Lyapunov exponents and the Kolmogorov–Sinai entropy for these multi-delay systems. A theoretical analysis shows how these roots move back toward stability as the number of delays increases. Our results are based on numerical determination of the Lyapunov spectrum for these multi-delay systems as well as on permutation entropy computations. Finally, we report how complexity reduction upon adding more delays can occur through an inverse period-doubling sequence.
Thermal conductivity modeling of monodispersed microspheres using discrete element method
Authors: Zeng Jian , Chung Ka Man , Zhang Xintong , Adapa Sarath , Feng Tianshi , Pei Yu , Chen Renkun
Published: October 2021

Particle beds are widely used in various systems and processes, such as particle heat exchangers, granular flow reactors, and additive manufacturing. Accurate modeling of the thermal conductivity of particle beds and understanding of their heat transfer mechanisms are important. However, previous models were based on simple cubic packing of particles, which could not accurately represent the actual heat transfer processes under certain conditions. Here, we examine the effect of the packing structure on the thermal conductivity of particle beds. We use monodispersed silica microspheres with average particle sizes ranging from 23 to 330 μm as a model material. We employ a transient hot-wire technique to measure the thermal conductivity of the particle beds with packing density of 43%–57% within a temperature range of room temperature to 500 °C and under N2 gaseous pressures of 20–760 Torr. We then use a discrete element method (DEM) to obtain the realistic packing structure of the particles, which is then fed into a finite-element model (FEM) to calculate the thermal conductivity, with the consideration of solid conduction, gas conduction, and radiation heat transfer. Our results show that the thermal conductivity model based on the more realistic random packing structure derived from the DEM shows better agreement with the experimental data compared to that based on the simple cubic-packing structure. The combined DEM and FEM methodology can serve as a useful tool to predict the effective thermal conductivity of particle beds and to quantify different heat transfer mechanisms under various conditions.
Adjusting oxygen vacancy and resistance switching of InWZnO thin films by high-pressure oxidation technique
Authors: Gan Kai-Jhih , Liu Po-Tsun , Hsu Chih-Chieh , Ruan Dun-Bao , Sze Simon M.
Published: October 2021

In this study, the room temperature high-pressure oxidation technique is proposed to exquisitely manipulate the surface morphology and oxygen depth-profile of the tungsten-doped indium zinc oxide (InWZnO) film, and its influence on the switching characteristics is emphasized. Based on the atomic force microscope analysis, the smoother surface morphology of the InWZnO film after the high-pressure oxidation treatment is observed. Moreover, it is observed that the InWZnO film has significantly manipulated the oxygen vacancy depth-profile and improved the chemical properties after high-pressure oxidation treatment, according to the x-ray photoelectron spectroscopy depth profiling results. Compared with the control device, the device with high-pressure oxidation treatment exhibited highly uniform resistance states and set/reset repeatability. Finally, the mechanism of the effect of high-pressure oxidation treatment on the InWZnO film is completely examined according to the in-depth material analysis and physical model discussed.
An achromatic pump–probe setup for broadband, few-cycle ultrafast spectroscopy in quantum materials
Authors: Amuah Emmanuel B. , Johnson Allan S. , Wall Simon E.
Published: October 2021

In this work, we present an achromatic pump–probe setup covering the visible (VIS) to near-infrared (NIR) wavelength regions (500–3000 nm) for few-cycle pulses. Both the pump and probe arms can work either in the VIS or the NIR wavelength regions, making our setup suitable for multi-color, broadband pump–probe measurements. In particular, our setup minimizes time-smearing due to the phase front curvature, an aspect of ultrafast spectroscopy that has been missing from previous works and allowing us to achieve sub-20-fs temporal resolution. We demonstrate the capabilities of our setup by performing measurements on Pr0.5Ca1.5MnO4. We pump and probe in both wavelength regions with a range of pump fluences and demonstrate how the observed dynamics depend strongly on the probe wavelength. Furthermore, the observation of a 16.5 THz phonon demonstrates the high temporal resolution of the setup.
Spin wave wavevector up-conversion in Y-shaped Permalloy structures
Authors: Liu H. J. Jason , Guerrero Aron , Nygren Katherine E. , Swyt Mitchell , Buchanan Kristen S.
Published: October 2021

Spin waves in micrometer-sized, patterned Y-shaped Permalloy structures were studied using micro-focus Brillouin light scattering (BLS) with a magnetic field applied in-plane. For in-plane magnetized thin films and microstrips, the dispersion relations depend on the angle of the magnetization with respect to the microstrip axis. BLS measurements show that spin waves generated in the two arms that form the top of the Y structure can be channeled into a longer magnetic microstrip that forms the base when the applied field is oriented perpendicular to the long axis of the base. In this configuration, the base supports surface spin waves. A comparison of the BLS data with micromagnetic simulations reveals that low-k spin waves generated by a microstrip antenna in the arms are converted to higher-k spin waves in the base, which may be useful for nanomagnonic applications.
High-speed impact of micron-sized diesel drop trains—Splashing dynamics, secondary droplet formation, and effects of pre-existing film thickness
Authors: Markt D. , Raessi M. , Lee S.-Y. , Zhu X.
Published: October 2021

This work investigates surface impingement of monodispersed diesel drop trains using computational simulations. The three-dimensional simulations include high-speed impact of micrometer-sized fuel drops onto initially dry and wetted stainless steel substrates. The drop size and impact velocity are representative of fuel injection conditions in internal combustion engines (ICEs). The drop trains serve as a simplified representation of fuel spray. To accurately capture the film that naturally develops on initially dry substrates, a dynamic diesel-stainless steel contact angle model was developed using experiments of single drop impact under ICE representative temperature. Simulations are presented for a highly splashing case and the effects of a pre-existing film on splashing dynamics were investigated, including the temporal evolution of splashed mass and film thickness. It was concluded that for thin films, the effect of pre-existing film thickness is less significant than in single drop impingement. Secondary droplet characterization was performed on simulation results, leading to instantaneous and time-averaged distributions of secondary droplet size, velocity magnitude, and trajectory angle. It was found that for each drop impingement, approximately 58% of the splashed mass is from the impinging drop itself, while the remainder of the splashed mass is composed of film liquid. From a high resolution case, details of secondary droplet formation are observed and three distinct phases of secondary droplet formation are identified. The detailed analysis of drop train impingement under engine-relevant conditions serves as a first step toward a robust understanding of fuel impingement and the development of cleaner and more efficient ICEs.
Dynamic compression of TiO2 to 221 GPa
Authors: Duwal Sakun , Root Seth , Farfan Bernardo , Reinhart William , Scott Alexander C.
Published: October 2021

The high-pressure dynamic response of titanium dioxide (TiO2) is not only of interest because of its numerous industrial applications but also because of its structural similarities to silica (SiO2). We performed plate impact experiments in a two-stage light gas gun, at peak stresses from 64 to 221 GPa to determine the TiO2 response along the Hugoniot. The lower stress experiment at 64 GPa shows an elastic behavior followed by an elastic–plastic transition, whereas the high stress experiments above 64 GPa show a single wave structure. Previous shock studies have shown the presence of high-pressure phases (HPP) I (26 GPa) and HPP II (100 GPa); however, our data suggest that the HPP I phase is stable up to 150 GPa. Using a combination of data from our current study and our previous Z-data, we determine that TiO2 likely melts on the Hugoniot at 157 GPa. Furthermore, our data confirm that TiO2 is not highly incompressible as shown by a previous study.
Tumorigenesis and cell competition in
Drosophila
in the absence of
polyhomeotic
function
Authors: Medina Izarne , Calleja Manuel , Morata Ginés
Published: October 2021

Significance

Because of the large number of cells, it is inevitable that the body of animals contains aberrant cells that may compromise the viability of the organism. Cell competition is a conserved mechanism responsible for removing those undesirable cells. Work in
Drosophila
and vertebrates has shown that cell competition also exerts a strong tumor-suppressing function, eliminating oncogenic cells that appear during the lifetime of the organism. Sometimes, however, oncogenic cells may overcome cell competition and develop invasive tumors. Studies of these situations may provide insights into the mechanisms by which oncogenic cells generate tumors in humans. We present new observations in
Drosophila
about the tumorigenic mutation
polyhomeotic
and how the mutant cells may evade the control of cell competition.
A microfluidic chip integrated with 3D sidewall electrodes and wavy microchannel for cell focusing and separation
Authors: Huang Liang , Wang Guiqiang , Zhan Guoqin , Pei Pei
Published: October 2021

Cell focusing and separation is a prerequisite for several biological applications. Among these technologies that can achieve the operation, dielectrophoresis (DEP) has been widely used due to its non-contact, label-free and easy-to-operate advantages. In this paper, we designed a microchip that integrates 3D electrodes and wavy microchannel for cell focusing and separation. The 3D electrodes act as not only the electrodes but also as the microchannel walls. The wavy microchannel enables 3D electrodes to generate electric field gradient required by DEP force in the entire microchannel. Cells can be focused and separated under the synergistic effect of DEP and fluidic forces. We have demonstrated the feasibility of the microchip through numerical simulations and experiments. And we validated our approach by demonstrating focusing and separation of A549 and HeLa cells. According to the electrical differences of cells, in the range of 61–99 kHz, the two types of cells can be focused into three streams under the action of positive and negative DEP force to achieve cell separation. With the increase of the voltage amplitude to 10 V, the width of the cell streams was focused to about 30 μm, which can improve the effect of cell separation, the separation efficiency of A549 and HeLa can reach 91.2% and 95.1%, respectively. The proposed microchip is expected to provide a new pathway for designing an effective cell focusing and separation platform.
Soliton dimer–soliton scattering in coupled quasi-one-dimensional dipolar Bose–Einstein condensates
Authors: Hegde Gautam , Nayak Pranay , Ghosh Ratheejit , Nath Rejish
Published: October 2021

We discuss scattering between a bright soliton and a soliton dimer in coupled quasi-one-dimensional dipolar Bose–Einstein condensates. The dimer is formed by each soliton from both tubes due to the attractive inter-layer dipole–dipole interaction. The dipoles within each tube repel each other, and a stable, bright soliton is stabilized via attractive contact interactions. In general, the scattering is inelastic, transferring the kinetic energy into internal modes of both soliton dimer and single soliton. Our studies reveal rich scattering scenarios, including dimer–soliton repulsion at small initial velocities, exchange of atoms between dimer and single soliton and soliton fusion at intermediate velocities. Interestingly, for some particular initial velocities, the dimer–soliton scattering results in a state of two dimers. At large initial velocities, the scattering is elastic as expected.
Transparent ultra-broadband absorber based on a tree seedling composite structure
Authors: Lyu Zhou , Zhang Binzhen , Duan Junping , Yang Yuhua , Liu Rui , Wei Yiqing , Liu Jingwen
Published: October 2021

In this work, we design, analyze and process an ultra-broadband absorption optical transparent metamaterials absorbing device. The simulation results show that within the 13.68–71.6 GHz frequency range, the devicereaches more than 90% absorptivity, and that transverse magnetic waves and transverse waves under a large angle of polarization and incident angle can obtain high absorption performance. Therefore the device has the perfect performance of polarization insensitivity and wide angle of incidence. The absorbing mechanism is analyzed by using the equivalent medium theory, and the theoretical results are in good agreement with the simulation results. Because of its advantages of wideband absorption, high transparency, lightweight, and easy availability, the deive has important application value in practical civil and military fields, such as electromagnetic interference, electromagnetic compatibility, super lens, invisibility cloak, solar cell device design and so on.
Higher order modal dynamics of the flexural ultrasonic transducer
Authors: Feeney Andrew , Kang Lei , Dixon Steve
Published: October 2021

The flexural ultrasonic transducer (FUT) consists of a piezoelectric ceramic bonded to an edge-clamped elastic plate, for both generation and detection of ultrasound waves. It is typically employed for proximity measurement, such as in automotive parking systems, and for flow measurement in gases and liquids. Conventional industrial applications have generally incorporated FUTs with resonance frequencies up to around 50 kHz. However, there have been recent advances in the understanding of the FUT, both in terms of fabrication and operation, enabling the potential for measurement in a wider range of applications, including those of elevated pressure, temperature, and requiring multiple operating frequencies. Ultrasound measurement with FUTs at frequencies greater than 50 kHz is desirable in a range of applications, including gas and water metering in petrochemical plants, district heating, and power industries. The major restricting limitation of designing transducers to operate at these higher frequencies has been a relatively poor understanding of these transducers work, including optimisation of design and performance, and the few reports into how different modes of a FUT can be utilised for practical and reliable measurement. In this study, the higher order modal dynamics of the FUT are investigated through measurement of high frequency ultrasound waves in air, for different fundamental operating modes. A combination of experimental techniques is applied, comprising electrical impedance analysis and laser Doppler vibrometry. The experimental research is supported by analytical solutions to reveal complex higher order modal dynamics of the FUT. This investigation represents further development in widening the industrial application potential of the FUT.
Innovative nanochemotherapy for overcoming cancer multidrug resistance
Authors: Tan Hong , Zhang Mengyu , Wang Yuqing , Timashev Peter , Zhang Yuanyuan , Zhang Shouwen , Liang Xing-Jie , Li Fangzhou
Published: October 2021

Tumor multidrug resistance (MDR) is a phenomenon in which drug-resistant tumor cells are resistant to multiple other unexposed antitumor drugs with different structures and targets. MDR of cancer is a primary cause of clinical chemotherapy failure. With the progress of nanotechnology in the medical field, more and more research works have developed many nanotechnology-based strategies to challenge drug resistance. This review details the recent studies at the National Center for Nanoscience and Technology utilizing various nanochemotherapy strategies for overcoming chemotherapy resistance of tumor. We discuss the benefits and limitations of the diverse strategies, as well as possible ways to overcome these limitations. Importantly, in order to combat cancer chemotherapy resistance with nanomedicine, the mechanisms of drug endocytosis and subsequent fate need to be explored and focused on. In the meanwhile, due to the complexity and diversity of chemotherapy resistance mechanisms, the development of more intelligent and controllable nanodrugs may have greater scope for clinical application.