bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid colonisation, breeding and successful recruitment of eastern barn owls (
Authors: Meaney Kelly M. , Peacock David E. , Taggart David , Smith James
Published: February 2021

Abstract Context The introduced house mouse (Mus domesticus) causes significant economic damage to Australia’s agricultural enterprises. As part of the Marna Banggara Rewilding Project on the southern Yorke Peninsula (SYP), the present study focused on the eastern barn owl (Tyto alba delicatula) as a potential bio-controller of mice, by providing nesting spaces where natural hollows are limited. Aims To design an appropriate pole-mounted wooden nest box, and to enhance barn-owl-breeding and house-mouse-hunting capacity on farmland adjacent to remnant native vegetation. Methods A prototype nest box was collaboratively designed with a nest box manufacturer using data from previous barn owl studies and anecdotal reports. Eleven pole-mounted wooden boxes with platforms were installed at distances >1.4 km apart on properties near Warooka, southern Yorke Peninsula (SYP), and monitored over a 6-month period using external trail cameras. Key results Of the 11 nest boxes installed, 55 percent were colonised within a month after establishment, and 82 percent were colonised within 7 months. Occupied nest boxes were actively used by paired owls for mating, breeding and rearing of chicks, which resulted in up to 35 fledgling owlets. Conclusions The nest box design successfully supported eastern barn owl colonisation and reproduction on the SYP. The inclusion of the platform not only provided easy, minimally invasive monitoring of barn owl activity and prey intake by researchers, but also increased usable space for barn owl behaviours, such as copulation and wing flapping. Implications The important nest box design elements featured in this paper, such as the platform, high entrance hole, predator-proof pole and rear door access, can be implemented in barn owl conservation, research and on farms where alternative nesting sites are limited.
Retail store customer flow and COVID-19 transmission
Authors: Shumsky Robert A. , Debo Laurens , Lebeaux Rebecca M. , Nguyen Quang P. , Hoen Anne G.
Published: February 2021

Significance

To reduce the transmission of COVID-19, many retail stores use one-way aisles, while local governments enforce occupancy limits or require “safe shopping” times for vulnerable groups. To assess the value of these interventions, we formulate and analyze a mathematical model of customer flow and COVID-19 transmission. We find that the value of specific operational changes depends on how the virus is transmitted, through close contact or suspended aerosols. If transmission is primarily due to close contact, then restricting customers to one-way movement can dramatically reduce transmission. Other interventions, such as reductions in customer density, are effective at a distance but confront store operators with trade-offs between infection rates and customer flow.
Sectional water fraction measurement for gas-water two-phase flow containing a conductive water phase utilizing capacitance sensor
Authors: Tang Kaihao , Hu Hongli , Li Lin , Wang Xiaoxin
Published: February 2021

By applying an electrical capacitance sensor to sectional water fraction measurement for gas–water (salinity) two-phase flow, this paper investigates the effect of a medium’s conductivity on the measurement of capacitance sensors and its elimination. Firstly, the mechanism of how a medium’s conductivity influences the capacitance measurement of a capacitance sensor is analyzed by combining a physical model of the sensor with its conditioning circuit. The theoretical analysis indicates that the applied exciting frequency is a key factor influencing the conductivity effect; the effect can be restrained by increasing the excitation frequency. Then, an exciting frequency optimization rule is proposed accordingly. In addition, sensor configuration and geometry optimization (based on finite element method simulations) are discussed to achieve better performance. Dynamic and static calibration experiments are carried out for stratified gas–liquid (salinity) two-phase flow for the purpose of validating the proposed method. The experimental results confirm the effectiveness of the proposed method. This work is constructive to the design of capacitive sensing technologies applied to conductive objects, and offers insights into the structural design and optimization of capacitance sensors.
Ratiometric pH sensing by fluorescence resonance energy transfer-based hybrid semiconducting polymer dots in living cells
Authors: Ding Zhaoyang , Dou Xilin , Wang Chunfei , Feng Gang , Xie Jing , Zhang Xuanjun
Published: February 2021

Intracellular pH plays a significant role in all cell activities. Due to their precise imaging capabilities, fluorescent probes have attracted much attention for the investigation of pH-regulated processes. Detecting intracellular pH values with high throughput is critical for cell research and applications. In this work, hybrid semiconducting polymer dots (Pdots) were developed and characterized and were applied for cell imaging and exclusive ratiometric sensing of intracellular pH values. The reported Pdots were prepared by blending a synthesized block polymer (POMF) and a semiconducting polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) to construct a fluorescence resonance energy transfer system for ratiometric sensing. Pdots showed many advantages, including high brightness, excellent photostability and biocompatibility, giving the pH probe high sensitivity and good stability. Our results proved the capability of POMF–MEHPPV Pdots for the detection of pH in living cells.
Electromagnetic form factors of Σ+ and Σ− in the vector-meson dominance model
Authors: Li Zhong-Yi , Xie Ju-Jun
Published: February 2021

Based on the recent measurements of the

e

+

e

−

→

Σ

+

Σ

¯

−

and

e

+

e

−

→

Σ

−

Σ

¯

+

processes by the Beijing Spectrometer III (BESIII) collaboration, the electromagnetic form factors of the hyperon Σ+ and Σ− in the timelike region are investigated using the vector-meson dominance model, where the contributions of the ρ, ω, and ϕ mesons are taken into account. The model parameters are determined from the BESIII experimental data of the timelike effective form factors ∣G
eff∣ of the Σ+ and Σ− baryons for center-of-mass energies from 2.3864 to 3.02 GeV. It is found that we can provide quantitative descriptions of the available data using as few as one adjustable model parameter. We then progress to an analysis of the electromagnetic form factors in the spacelike region and evaluate the spacelike form factors of the hyperons Σ+ and Σ−. The electromagnetic form factors obtained for the Σ+ and Σ− baryons are comparable with those of other model calculations.
An Uplink Secure CB-NOMA with SIC Receiver for Wireless Applications
Authors: Al-Musawi Israa M. , Al-Hussaibi Walid A. , Tahir Yaseen , Ali Falah H.
Published: February 2021

The nonorthogonal multiple access (NOMA) techniques are considered one of the main methods to realize the goals of 5G mobile and wireless systems such as link communication reliability and high user connectivity. Yet, when the amount of simultaneously connected users increases, many concerns will arise regarding the users’ data security. Various chaotic systems in the communication field have been presented to mitigate the data security concerns offering a cost-efficient technique to provide physical layer security. This work presents an uplink secure chaos-based NOMA (SCB-NOMA) system by exploiting the power domain. For signal modulation at the transmitters’ node, chaos shift keying is used, with controlled transmit power to satisfy the receiver conditions. For multiuser detection, the receiver side employs successive interference cancellation with chaotic demodulation. The efficiency of designed SCB-NOMA is demonstrated by considering different power control factors, system scenarios, and chaotic sequence length compared with different reference systems. It is shown that the efficient selection of the power allocation parameter has a direct effect on the bit error rate (BER) performance. Meanwhile, when the amount of power difference for the successive interference cancellation process is not adequate, the chaotic codes maintain the desired data security and enable robust BER performance for connected users. Besides, the correlation between the utilized chaotic codes has more impact on BER regardless of the considered sequence length.
Solving forward and inverse kinematics problem for a robot arm (2DOF) using Fuzzy Neural Petri Net (FNPN)
Authors: Zayer Wael Hussein , Maeedi Zahraa Ali , Ali Abdul Jabber Fathel
Published: February 2021

At a time the robots become an important part of our lives by carrying them many tasks that require strength and accuracy, controlling these robots and giving them high accuracy and performance has become the focus of attention of workers in this field. In this research, one of the problems of controlling the robot arm is represented, where the problems of the forward and inverse kinematics have been addressed and find solutions to it using the artificial intelligence algorithm fuzzy Neural Petri net. The Matlab program was used to simulate the forward and reverse kinematics equations and then use the simulation results as data (inputs, outputs) for the proposed algorithm and run the program to update weights and give the required results depending on the ratio mean square error given.
Numerical study of PCM melting processes in trapezoidal channel
Authors: Abdulrahman Ruslan , Ibrahim Farah , Al-Mudhafar Ahmed , Dakhil Sadoun
Published: February 2021

In this paper, a numerical investigation had been performed to improve the melting process of phase change materials (PCM) by utilizing a trapezoidal channel. Different geometrical parameters of the trapezoidal channel were investigated. These parameters included: the height and pitch of the trapezoidal channel. Two-dimensional numerical models were developed with ANSYS (FLUENT) software. The unit is a horizontal channel that the heat transfer fluid (HTF) (hot water) passes through the channel to melt the PCM which contained at the top and bottom sides of the channel. The results showed that the trapezoidal channel with a longitudinal pitch of 6 mm and a height of 4 mm is the most suitable parameters for increasing the PCM melting process compared to other geometrical parameters. It was also concluded that the melting time is decreased by 27% at a height of 4 mm, and by 8% at a pitch of 2 mm.
Experimental Enhancement of Mixed Convection Heat transfer in Hot Base Rectangular Channel
Authors: Dakhil S F , Najim AQ , Abood FA
Published: February 2021

This paper presents an experimental study to enhance the flow and heat transfer enhancement over horizontal and orientation channel with hot base by laminar mixed convection heat transfer. The hot base is fitted with the longitudinal rectangular fin arrays as a finned wall. The study covered the following range: modified Grashof number varied (3× 101 - 8× 108), Reynolds number in range 1800-2300, and Pyrantel number 0.71. The bottom finned wall of the channel was supplied with constant heat flux, while the other sides are insulated. The experiment part includes a suitable test rig that was built to get accurate decisions. A good mechanism was created to get the orientation angles at (90°,120°, 150 °and 180°) then to analysis this effect on heat transfer for laminar flow force convection. Three different cases are investigated: the effect of modified Grashof number and orientation angles on fluid particles flow and heat removal will be an enhancement. The experiment results show that the average heat transfer coefficient increased with Reynolds number and an increase of the Grashof number for all orientation angles due to increases buoyancy forces, thus causes a detach with the secondary layer flow. The average heat transfer coefficient and fins effectiveness are enhanced to 25% at highest longitudinal orientation angles.
Investigation on the Analysis of Bending and Buckling for FGM Euler-Bernoulli Beam Resting on Winkler-Pasternak Elastic Foundation
Authors: Mohammed Ali Taha , Hareb Maroa Ali , Eqal Asaad Kadhem
Published: February 2021

In this paper, Functionally Graded Material (FGM) has been analyzed to examine bending and buckling of simply supported beams. Using Euler-Bernoulli beam theory (EBT), these beams that rested on Winkler-Pasternak elastic foundation are exposed to two types of loads that are axial compressive force and distributed transverse load. Here, based on power-law distributions, the properties of the material of FGM beam is assumed to be varied at the direction of the thickness. The derivation of the FGM beams’ governing equations was done using the total potential energy principle. The transverse deflection and the critical buckling of the FGM beam were determined using the Navier-type solution method with simple boundary conditions. A closure on the effects of the power-law exponent of FGM, and the spring constant with the shear constant of elastic foundation on the transverse deflection and critical buckling load was achieved. A validation study for numerical results was carried out here with previous results from the literature and they are said to be in excellent agreement. It is shown by the numerical results that critical buckling load is decreasing with increasing both, slenderness ratio and values of power-law exponent and vice versa for transverse deflection.
Effect of different geosynthetic reinforcement materials on transmitted pressure under dynamic machine foundation
Authors: Karim H H , Samueel Z W , Hussein M A
Published: February 2021

The present study has been carried out to study experimentally the contact pressure transmitted of dynamic machine foundation on unreinforced and reinforced multi-layered sandy soil (medium-dense sand MD). The relative density of the first layer was 50% corresponding to medium sand soil, while the relative density of the second layer was 85% corresponding to dense sand soil. The tests have been carried out on 8 models. The amplitude of the applied harmonic load was 0.25 ton and 2 ton with a frequency of 0.5 Hz. For each load amplitude, models of sand were tested in two cases reinforced and unreinforced models. Three types of reinforcements were used at 0.5B depth where B is the width of the square foundation. Analyzing the dynamic behavior of tested soil samples and presenting of some concluded remarks were done.
Analyzing and Predicating PH value in Nature Rubber Solidification Process Using Multiple Regression Method
Authors: Sun Zhongrui , Wang Bingbing , Zhang Fan , Liao Lusheng , Deng Weiguo , Zhang Yuan
Published: February 2021

Acid coagulation is the most common process in nature rubber(NR) processing and the acid concentration in latex is a key factor that will decide the quality of processed rubber. In order to invalid the change of PH value processed with acid concentration on latex clots, a group division experiment is designed to obtain the data of PH value, smell and color in latex clots under different solidification time, mode, and temperature. Then a multiple regression model based on Statistical Product and Service Solutions (SPSS) is used to analyse and predicate the PH value in different conditions. The result shows that predication method can have a good result and the average relative error of PH value is 4.60%.
Ultrasonic manipulation of cells for alleviating the clogging of extrusion-based bioprinting nozzles
Authors: Shao M H , Cui B , Zheng T F , Wang C H
Published: February 2021

Extrusion-based bioprinting is one of the most common biomanufacturing methods. The bioink composed of biomaterials and living cells is extruded into cylindrical filaments. The filaments are deposited on the substrate and stacked layer by layer to form a three-dimensional structure. During the extrusion process, the ink tends to accumulate at the nozzle, which clogs the nozzle and increases extrusion pressure, resulting in the decrease of cell survival rate. Here, we propose a method of using ultrasound to manipulate cells to assist the bioprinting process, which can alleviate nozzle clogging. The ceramic piezoelectric plate(PZT) is used to drive the nozzle to generate structural resonance, and the ultrasonic standing wave generated by the vibration make the cells/particles in the ink gather at the center of the nozzle, thereby reducing the risk of clogging of the nozzle. In this paper, we first analyze the mechanism of the standing wave generated in the cylindrical elastic nozzle and drive the cells to move under the PZT drive, and then use the finite element software to simulate the standing wave drive process. The results show that this method can be solved by a simple and low-cost device. The results indicate that this method has the possibility of using simple and low-cost equipment to solve the problem of nozzle clogging in bioprinting.
Casting process of gate valve steel based on ProCAST simulation
Authors: Qin Shanpeng , Lv Peng , Li Sirun , Li Yongcun
Published: February 2021

The sand casting process of 18CrNiMo7-6 gate valve casting was designed in this paper. The molding and core making methods of castings are sodium silicate CO2 method and self hardening cold box method respectively. The technological parameters of the casting were determined. The middle pouring system and top riser were designed. Using software to draw the assembly and 3D entity of gate valve casting. ProCAST simulation software is used to realize the numerical simulation task of the gate valve casting process. Shrinkage and porosity are the main research objects. It is found that the defects mainly appear in the thick part of the casting and the flange through the simulation experiment feedback parameters. In this paper, from the point of view of reducing and avoiding defects, the casting process is improved and improved. Finally, according to the experimental results, S2 (with chill) is determined as the final scheme.
Research and evaluation of the measurement uncertainty with the comparator
Authors: Hu Chang’an , Li Jiangang , Ouyang Hongmei , Luo Shutong , Lv Fei , Cai Dongyan
Published: February 2021

As a kind of portable three-coordinate, the comparator is playing an more and more important role in precision industry measurement. Therefore, it is of great scientific significance and obvious socioeconomic benefits to carry out the research of comparator. This paper was based on rich experience with the institute in the field of the geometric measurement technology for a long time. And the measurement uncertainty of the instrument has been researched. The uncertainty of the diameter indication error is U=1.2μm k=2, the uncertainty of roundness indication error is U=1.4μm k=2, the uncertainty of sphere-center distance error is U=1.5μm+7.2×10−6
L k=2 L:m, and the uncertainty of length indication error is U=1.2μm+1.5×10−6
L k=2 L:m.
Research on 3D Printing layered Algorithm based on FDM Technology
Authors: Jia Hongwei , Xu Wei
Published: February 2021

Fused deposition forming (FDM) is the most mature 3D printing technology, which has been widely used in many fields of our daily life, science and technology, and economic development.In the molding process of the model, how to choose the appropriate layering method has become the key point to improve the precision and efficiency of 3D printing. Based on adaptive layered algorithm was studied, using three-dimensional modeling software of entity modeling, the introduction of the z axis curve contour curve is determined, and then segment, find out each section contour tangent to the curve, calculated the contour tangent with the model the Angle between the positive direction, an analysis model of layer thickness;The lamination thickness of the model is calculated by using probability statistics, summation superposition and other mathematical methods.Practice has proved that the adaptive layering method is clear in process and simple in calculation, which reduces the workload of layering to a certain extent and improves the precision and efficiency of 3D printing molding.
Simulation Analysis of Influencing Factors of High Pressure Phase Transformation in Single Crystal Germanium Ductile Cutting
Authors: long Bi Jiao , Shi Guang feng , Jiang Fei , Shi Guo quan , Xia Ming qiang
Published: February 2021

The high-pressure phase Ge-II of germanium has similar metal cutting characteristics. In single-point diamond turning, in order to maximize the high phase transition zone of germanium, that is easily to make ductile cutting realized. The single factor test method is used to simulate the ultra-precision turning process under different machining process parameters and tool geometric parameters. Through the calculation of the area of the high-pressure phase change zone in the simulation results and the description of the cutting temperature change law, the influence law of different process parameters and tool geometry parameters on the evolution of the phase change zone is obtained, which provides a useful reference for the choice of turning test parameters.
A Flexible Resistive Strain Sensor Based on Mixed Carbon Nanomaterials
Authors: Chen Yucheng , Zhang Peng , Zhang Jian , Huang Liangsong
Published: February 2021

With the development of flexible electronic technology, flexible strain sensors are playing an increasingly important role in human motion detection and medical health. It is still an important research topic to consider the sensitivity and stability of flexible strain sensors in practical applications. This work describes a new type of flexible resistive strain sensor that uses a new and simple method to embed sensitive materials on the surface of a flexible substrate. The flexible strain sensor has both excellent stability and good flexibility. The sensor has a gauge factor of 5.875 in the strain range of 0-5%, and a gauge factor of 4.252 in the strain range of 10%-120%. The sensor remains stable over 1000 repetitions. The sensor can be used to detect human movements, including large-scale movements of human limbs and small-scale bending of finger joints. Because of its simple manufacturing process and excellent characteristics, it has shown great potential in medical health and smart wearable devices.
Design and Analysis on Mixed Line Welding Fixture for Light vehicle
Authors: Shu-guang SUN , Meng WANG
Published: February 2021

The existing welding has some defects that can only be used for a single type of vehicle body and cannot apply to mixed line welding for several vehicle types. According to the structure characteristics and normalization design requirements of body welding fixture, the existing four light vehicle body structure parameters, clamping fixture and welding process requirements are analysed, so that a modular fixture which is suitable for four kinds of light vehicle body with mixed line repair welding is designed, which includes flexible clamp concrete, pressure control system, the single-chip microcomputer control, and mixed line of three kinds of switch control method.
The natural properties analysis of a power turret gear system based on the varying mesh stiffness
Authors: Xu Lijiao , Zhou Pan , Zang Liguo
Published: February 2021

As the time-varying contact stiffness is one of the most important nonlinear factors, which not only has great influence on dynamic properties, but also on the natural properties. In this paper, the natural properties of a power turret gear system were studied based on varying stiffness. The influence was concluded by natural frequencies.
Ultrasound-assisted 3D printing platform and method capable of flexibly adjusting layer thickness and rotation angle
Authors: Wang Z Y , Cui B , Zheng T F
Published: February 2021

The technology of arranging particles by ultrasound has matured. In recent years, this technology has been used as a basis for arranging particles in a photocurable resin for stereolithography (SL). In order to process the resin doped with particles to obtain a variety of particle arrangement patterns, most of the previous work chose to use different polygonal containers to obtain single-layer fiber angles. In this adjustment mode, the selectivity of the fiber angle is very poor, usually 45°, 90° and other common angles. In this work, we designed and manufactured a new ultrasound-assisted 3D printing platform that can flexibly adjust the thickness of the sandwich and the rotation angle of the sandwich. We will introduce the basic working principle and matching usage of the device, and show some basic print samples.
A simple way to achieve black-and-white designs in topology optimization
Authors: Xing Jian , Qie Longfei
Published: February 2021

In order to obtain crisp black-and-white designs, it is vital to use filtering techniques in density-based topology optimization. However, the applying of filters result in a large number of gray transition zones between the solid and void phases in the final designs. To solve this problem, a dynamic parameter tuning method is proposed in this paper. With the approach, the filter radius can be dynamically adjusted during the optimization process, thereby suppressing the gray elements in the final designs. The proposed method is tested by the classic MBB beam problems. The experimental results show that the proposed method can effectively inhibit the appearance of gray transition areas in the optimization results.
Numerical research on the effect of aircraft leading-edge curvature on bird strike resistance
Authors: Su K , Bai R X , Bai H S
Published: February 2021

With development of aviation industry, bird strike becomes great threat to flight safety. Numerical study has attracted widely attention due to high-cost experimental test. In this paper, Smooth Particle Hydrodynamic (SPH) couple with Lagrangian method is taken to study on the effect of both material and aircraft leading-edge curvature on bird strike resistance. Simulation result shows that fiber-metal material structure can offer greater impacting stiffness than aviation aluminum alloy materials. Besides, appropriate reduction of the curvature radius on the top of skin of leading-edge is beneficial to improve the structural stiffness, however, when curvature radius is too small, the impact resistance of the structure becomes worse due to matrix damage of material. The work in this paper may provide reference for the design of leading-edge structure.
Research on wheat modeling method based on EDEM
Authors: Chen Song , Cao Shukun , Gao KuiZeng , Cao WenLong , Cui Shoubo , Ma Jianzhong
Published: February 2021

Based on the actual shape of the wheat, the size of 50 wheat grains was measured, and the average value was used to construct a three-dimensional map. Then, the sphere of 0.2mm is filled automatically in the API of discrete element software, and the model is compared with the filling model included in the software. The method of bottomless cylinder stacking angle is used to simulate and compare with the actual experiment. The results show that, compared with the actual test results, the error of API automatic filling model and manual filling model is 3.08% and 14.00% respectively. This result proves that the model of API automatic filling is closer to the wheat grain in real life.
Optimal design of structure parameters of coaxial powder feeding nozzle for laser cladding
Authors: Su Peng , Li Hu , Yang Jianyu , Huang Dong
Published: February 2021

Aiming at the problems of large powder gathering diameter, low powder utilization rate, easy clogging of the nozzle, poor cooling water system effect and unstable powder feeding effect existing in the existing nozzles, an improved laser cladding coaxial powder feeding nozzle with external shielding gas structure is optimally designed. The response surface method and the BP neural network optimized by genetic algorithm are used to optimize the nozzle structure parameter combination. After the nozzle structure parameter combination is determined, the external shielding gas structure parameter range is determined according to the nozzle structure parameter combination. The unsupported laser cladding coaxial powder feeding nozzle is made of photosensitive resin material, and the powder feeding effect is verified. The optimized nozzle is measured for the powder converging point, powder converging diameter and powder utilization rate, which verifies the validity of the simulation results.
Solutal convection in a horizontal porous layer with clogging at a high solute concentration
Authors: Maryshev Boris S , Klimenko Lyudmila S
Published: February 2021

The authors study the transport of solute particles in a horizontal layer of a porous medium taking into account the clogging process for a wide range of solute concentrations. On the basis of the most popular and experimentally confirmed MIM model with saturation of the immobile phase, a closed equation system describing such transport is derived. The concentration dependence of porosity is described within the Kozeny-Carman model. The criteria for the transition to the popular model of weak clogging, when the solute concentration is significantly lower than the porosity of the medium, are considered. It is shown that the basic state for the model does not correspond to the classical linear distribution of mobile solute. The convective instability of horizontal seepage with respect to two dimensional perturbations is studied. The critical curves in the space of problem parameters are obtained.
Wave-like concentration profiles of a diamagnetic admixture in a cholesteric liquid crystal
Authors: Sokolchik D P , Makarov D V
Published: February 2021

The behavior of the orientation structure of a suspension of diamagnetic particles based on a cholesteric liquid crystal in an external magnetic field is theoretically studied. The effects of magnetic segregation and rigid homeotropic coupling between the liquid crystal matrix and admixture diamagnetic particles are taken into account. Within the framework of the continuum approach, a system of equations for the orientation equilibrium of the suspension was obtained using standard variational procedures. In the limit of weak magnetic fields, analytical dependences describing the behavior of the director vector field and the distribution of the admixture concentration along the suspension helix are obtained. A significant influence of the anisotropy parameter of the diamagnetic susceptibility subsystems on the wave-like concentration profiles in the suspension was revealed.
Numerical investigation of double-diffusive convection at vibrations
Authors: Kozlov Nikolai
Published: February 2021

The problem of convection in a rectangular vertical cell, located in the gravity field and under the action of high-frequency vertical vibrations, is solved using the direct numerical simulation. At the initial moment of time, the system is formed by two horizontal layers of miscible liquids: the lower (heavy) layer is an aqueous solution of sodium chloride, while the upper one is a sugar solution. A two-dimensional formulation is considered; ANSYS Fluent software package is used as a solver. The impermeability and no-slip conditions are satisfied at the cell boundaries. As a result of the difference in the diffusion coefficients of dissolved species, layers with unstable stratification are formed over time near the contact zone. This leads to the onset of convection in the form of thin ascending and descending fingers. The vibrations, on average, lead to a decrease in the growth rate of fingers and the velocity of convection. In the case of relatively high vibrational overloads, a more regular convective structure forms in the diffusion layer leading to a more pronounced mixing of fluids.
Experimental and numerical study of acoustic pressure distribution in a sonochemical reactor
Authors: Kuchinskiy M O , Lyubimova T P , Rybkin K A , Fattalov O O , Klimenko L S
Published: February 2021

In this work, it is shown numerically in COMSOL Multiphysics and experimentally that a change in the NaCl concentration in water significantly affects the distribution of acoustic pressure in a laboratory sonochemical reactor. Thus, in distilled water under the action of ultrasound, two areas of increased pressure were ob-served, one of which was located directly above the ultrasound source, and the second was near the surface of the liquid, this effect is associated with the reflection of sound waves from the surface of the liquid. With the increase in the salt content, the maximum value of the acoustic pressure in the liquid decreases, which is associated with the dependence of the acoustic impedance of the liquid on the salt concentration and the peculiarities of the dynamics of vapor-gas bubbles in such solutions.
Oscillatory dynamics of two liquids interface in straight narrow gap
Authors: Vlasova O , Kozlov V
Published: February 2021

Oscillatory dynamics of the liquid-liquid interface in a straight slot channel is studied experimentally. We use fluids with a large difference in viscosity and similar densities. The experimental conditions are chosen in such a way that the oscillating motion of a low-viscosity liquid is inviscid, and the oscillating motion of viscous liquid obeys Darcy’s law. At the beginning of the experiment, the interface is oriented perpendicular to the channel axis. It is found that the interface takes a shape of a symmetric hill curved towards a viscous liquid under liquid oscillations. The equilibrium interface shape (the hill height) is determined by the amplitude of the interface oscillations.
Gravity level influence on the onset and nonlinear regimes of a binary mixture convection in rectangular cavity heated from below
Authors: Rushinskaya K S , Lyubimova T P , Zubova N A
Published: February 2021

In this paper we present the results of numerical simulation of nonlinear convection regimes of a NaCl aqueous solution heated from below. The calculations are carried out for square and horizontally elongated rectangular cavities, both in the approximation of a constant thermal diffusion coefficient and in case of taking into account its temperature dependence. Other transport coefficients are considered as constant. We observe the local and integral characteristics of the realized flows at constant and variable thermal diffusion coefficients in the conditions of the Earth and reduced gravity.
Modeling optoelectronic converting structures using the ZEMAX software package
Authors: Bushuev A. S , Zolotov A. N , Firsov I. V , Efremov I. M
Published: February 2021

The paper is devoted to the study of the possibility of constructing a digital conversion on new optoelectronic principles that will expand the frequency range of the conversion, as well as increase the bit conversion, thereby improving accuracy. The basic configuration options of radiating elements in digital-to-analog conversion systems are considered. Simulation was carried out using the ZEMAX software package. The dependence of the conversion of an input digital signal into an analog signal at a photodetector is investigated.
Forming microstructures of certain transparency on thin titanium films by laser thermochemical method
Authors: Nguyen Q.D. , Shakhno E.A. , Sinev D.A. , Zakoldaev R.A. , Veiko V.P.
Published: February 2021

Controllable transparency level is the key parameter for production of the grayscale masks for the aims of submicron photolithography. In this work, we have developed an analytical model to predict transparency dependencies of the irradiated areas on thin titanium films during laser oxidative treatment. This allows controlling final optical properties of submicron recorded areas by tuning the parameters of laser fluences, initial film thicknesses, and laser wavelengths in the wide ranges. Modelling results were confirmed by experimental investigation and can be used to optimize the recording process by the preliminary planning the required levels of transparency and necessary laser treatment parameters.
Tunable near infrared laser
Authors: Putilov A.G. , Antipov A.A. , Shepelev A.E. , Arakelian S.M.
Published: February 2021

The article introduces a tunable NIR laser. The tuning process realizes by the dispersion elements placed inside the resonator. Energy parameters depending on the laser operating mode are presented. The possibility of smooth tuning of the fundamental lasing wavelength depending on the rotation parameters of the dispersion element is shown.
Ablative laser processing of titanium surface in n-hexane
Authors: Kochuev D.A. , Chkalov R.V. , Chkalova D.G.
Published: February 2021

The work is devoted to the problem of high-spherical powders synthesis by the method of laser ablation processing of refractory metals. An investigation of interaction of ultrashort laser pulses with titanium in an n-hexane medium has been carried out. The dependence of granules size and dispersion of synthesized micro- and nanoparticles on the parameters and processing conditions, namely, laser radiation energy, scanning speed, working medium and pressure is shown.
Anomalous thermodynamics in homogenized generalized Langevin systems
Authors: Lim Soon Hoe
Published: February 2021

We study functionals, such as heat and work, along trajectories of a class of multi-dimensional generalized Langevin systems in various limiting situations that correspond to different level of homogenization. These are the situations where one or more of the inertial time scale(s), the memory time scale(s) and the noise correlation time scale(s) of the systems are taken to zero. We find that, unless one restricts to special situations that do not break symmetry of the Onsager matrix associated with the fast dynamics, it is generally not possible to express the effective evolution of these functionals solely in terms of trajectory of the homogenized process describing the system dynamics via the widely adopted Stratonovich convention. In fact, an anomalous term is often needed for a complete description, implying that convergence of these functionals needs more information than simply the limit of the dynamical process. We trace the origin of such impossibility to area anomaly, thereby linking the symmetry breaking and area anomaly. This hold important consequences for many nonequilibrium systems that can be modeled by generalized Langevin equations. Our convergence results hold in a strong pathwise sense.
Using the Extract of “Saprolin” for Enhancing Grain Crops
Authors: Nazarova T V , Dmitriyev P S , Baryshnikov G Ya
Published: February 2021

The solution to the problems of enhancing the yield of grain crops in current agriculture development is not conceivable without applying new land processing technology and using mineral fertilizers. Simultaneously, to obtain environmentally friendly products in organic farming, it is required to use mineral organic fertilizers in large quantities. For these purposes, we developed manufacturing technology and proposed the extract of “Saprolin.” This extract, obtained from organogenic lake storage, is supposed to be used for pre-sowing seed treatment, contributing to providing the planting material with biologically active substances, macro- and microelements, and natural soil conservation. During the production of the extract from the obtained source material, solutions of different concentrations were prepared, and their features (viscosity, density, electrical conductivity, refractive index, and pH of the medium) were studied. Using the wheat seeds “Novosibirskaya-31” and barley “Astana-2000” as an example, under the influence of solutions of the obtained extract, the germination and vigor of seeds were determined. As it was proved in experiments, the obtained extract is a good germination stimulant for grain crop seeds. It has a greater effect on seed vigor. Nevertheless, seeds with high vigor are the most viable, give good yield, and provide high-quality products. The germination rate significantly affects plants’ survival, shows the speed of their growth, and characterizes the ability of seeds to germinate in the field evenly (good uniformity). The research determines the germination and vigor of seeds using processing solutions of different concentrations. The research shows that the obtained extract of “Saprolin” increases the germination of seeds of grain crops by 1%–9% and vigor by 12%–19%. The extract of “Saprolin” is classified as a herbal stimulant containing a water-soluble natural mineral substance for improving plant nutrition.
Status and Development Prospects of Horse Breeding in the Altai Region
Authors: Zaycev A M , Koveshnikov V S
Published: February 2021

The transition to a market economy caused significant changes in the number of horses and their distribution by category of horse owners, regions, and economic use areas. This study aims to identify the natural and economic factors affecting the quantitative and structural features of the horse breeding industry in the Altai region. More than that, the research discusses critical parameters of its optimal development in the medium term. In 1991-2018, in Altai, the horse population decreased from 226.8 to 161.3 thousand heads (28.9%). However, due to higher decreases of horse livestock in other Russian regions, the share of Altai horse owners in the Siberian Federal District increased from 34.0 to 38.5%. The country-wide share increased from 8.7% to 12.6%. While the number of horses in the Altai Krai decreased 2.6 times, in the Altai Republic, it increased by 28.9 thousand heads, exceeding the pre-reform level by 38.3%. Until 2025, with the stabilization of the number of workhorses, meat horse breeding will be the central development area. The number of meat horses will increase in Altai from 112.6 to 126.8 thousand heads, which, with rational management, would ensure the production of over ten thousand tons of high-quality meat for domestic consumption and export.
The Impact of Short-Wave UV Radiation on Peroxidase Activity in Soft Wheat Seeds
Authors: Sharlaeva E A , Chirkova V Yu
Published: February 2021

The effect of UV radiation on plants provokes oxidative stress, accompanied by the production of reactive oxygen species that can have a direct destructive effect on cellular structures and initiate free radical oxidation of proteins, lipids, and nucleic acids. There is an antioxidant defense system in plant cells that includes a complex of low and high molecular weight compounds. Antioxidants with high molecular weight are enzymes, the key of which is peroxidase [PO]. The paper studies changes in PO activity in soft spring wheat seedlings due to grain treatment with small and medium doses of short-wave UV radiation. A UV-dosed irradiation system (Bio-Link Vilber) with the exposure time 0–60 minutes in increments of 10 minutes was used for seed treatment. Pre-soaked wheat seeds were germinated in Petri dishes. PO activity was determined colorimetrically in three-day-old wheat seedlings, according to A. L. Boyarkin [3]. When the source was irradiated for up to 30 minutes, a clear dependence of the PO activity on the exposure time was not established. The maximum increase in peroxidase activity (by 25.9% relative to the control) was detected with 30-minute UV irradiation. A further increase in exposure time led to a significant decrease in enzyme activity. Moreover, vital feedback was revealed between the activity and exposure time in the range of 30–60 minutes.
Features of Microclonal Reproduction and Organogenesis of the Far Eastern Species Aristolochia Manshuriensis Kom. as a Biological Resource
Authors: Demidenko E N , Berseneva S A
Published: February 2021

Plants of Manchurian birthwort (Aristolochia manshuriensis Kom), obtained under in vitro conditions, are characterized by a high potential for accelerated reproduction by weakening the action of their growth hormones during a certain period of phenological development and as a result of a response to the presence of 1mg/l IMK in the nutrient medium. Thus, the microplants can adapt to the conditions of the closed soil, while the total percentage of survival is 49.12%.
The Natural Potential of the Sharyn River Basin as the Basis for Developing Health Tourism in Kazakhstan
Authors: Kerimbay B S , Dunets A N , Baryshnikova O N
Published: February 2021

The paper analyzes the tourist and recreational potential of the Sharyn River basin, which can serve the basis for further development of health tourism centers. The research is based on field studies of landscapes conducted in summer 2019 in the Sharyn River basin. Four key sections were laid along the Sarytugay, Moyyntukay, Temirlik, and Shonzhy routes. A digital thematic map was created in ArcGIS 10.1. The landscapes of the Sharyn River basin have a significant natural potential for developing a combined type of tourism, which includes the medical and recreational aspects of providing tourism services. Transport accessibility, a long warm season, the prevalence of clear weather in summer, attractive landscapes and water bodies, and significant biodiversity make this territory a very promising place for organizing ecological, educational, and recreational tourism. The authors note that the Sharyn State National Natural Park and the UNESCO Sharyn Biosphere Reserve are located in the studied region, and this fact guarantees preserving natural recreational resources and developing tourist routes. The sparsely populated area allows to observe animals and plants in their natural habitat. The complex of the piedmont plain Ketmen allows providing a wide range of sanatorium services, including thermal waters for heating buildings and organizing greenhouses. To prevent negative consequences of unorganized tourism and justify further investments in recreational resources development, the authors provided recommendations that would ensure the sustainable development of medical tourism. This fact creates prerequisites for forming a new health and tourist cluster of international importance in Kazakhstan.
Changes in Heart Rate Autonomic Regulation in Girls at The Age of 10–11 with Different Rates of Biological Maturation: A Two-year Study
Authors: Filatova O V , Bogdanova T A , Tomilova I N
Published: February 2021

The authors conducted a two-year study of 60 girls aged 10-11. The analysis of the features of heart rhythm autonomic regulation in girls with different biological maturation rates revealed the following. The girls with slower sexual and physical development rates at the age of 10 are marked with higher values of very-low-frequency (VLF) waves, lower values of the high-frequency component of HF than a group of children having the above-average level of physical and sexual development. The groups of 10-year-old girls with different physical and sexual development levels differ in basic anthropometric measurements, body composition parameters, and basal, specific, and norm-based metabolic rates. By the age of 11, girls with the due acquisition of secondary sexual characters demonstrate an increase in sympathetic influence and a decrease in parasympathetic effect on HR’s variability. The obtained data indicate a relative lag in the functional development of the cardiovascular system autonomic regulation in girls with the delayed acquisition of secondary sexual characters at the age of 10 compared to the group of children with the above-average level of physical and sexual development.