bluuebunny/crossref_metadata_2025_split huggingface dataset:
A friction factor in rectangular microchannel of 100 μm depth
Authors: Gluzdov D S , Gatapova E Ya 
Published: December 2020

Abstract
The dependence between the shear stress and integral flow parameters such as fluid flow rate still remains unclear for different microchannel geometries. We present results of the numerical simulation of the 3D fluid flow in a microchannel with a rectangular cross section. Basing on the experimental measurements of the pressure drop the fluid flow and the shear stress are analyzed in detail giving the correlations for the friction factor. The results show that the shear stress for a numerical calculation can be estimated using friction factor from the well-known formula with a slight deviation due to wall and corner effects which can be important with the reduction of microchannel size.
Effect of the inlet flow rate ratio on liquid efficiency in a T-shaped micromixer at low Reynolds numbers
Authors: Kravtsova A Yu , Kashkarova M V , Ianko P E , Bilsky A V , Kravtsov Y V 
Published: December 2020

Abstract
The effect of the ratio of inlet flow rates on the flow structure and efficiency of liquid mixing in a T-shaped micromixer was studied at low Reynolds numbers using the method of particle image velocimetry and laser-induced fluorescence techniques. It was found that under the stationary flow regimes, the maximum efficiency of liquid mixing is 0.86 at Re = 186 and inlet flow ratio (R) of 1. The maximum dimensionless value of the longitudinal component of the mean flow velocity (up to 2.0) is achieved for the cases with the smallest and largest inlet flow ratio, that is, at R = 0.03 and R = 1.
Experimental study of droplet detachment from liquid film surface by a co-current flow inside the nozzle stagnation chamber
Authors: Prikhodko V G , Yarygin V N , Yarygin I V 
Published: December 2020

Abstract
The paper presents the results of an experimental study on the interaction of near-wall liquid film with the co-current gas flow in the convergent channel. Conditions for transition (co-current gas flow velocity and liquid flow rate) of near-wall liquid film from annular flow mode to annular-dispersed flow accompanied by a detachment of droplets from the interface are elucidated.
Laboratory simulation for single and block supersonic jets
Authors: Zarvin A E , Krylov A N , Yaskin A S , Antipova M S , Kalyada V V , Gerasimov Y I , Dubrovin K A , Khudozhitkov V E 
Published: December 2020

Abstract
Model experimental studies are presented for the flow field of a single jet, the flow parameters of a block jet, the pressure distribution on the bottom screen, and the parameters of the jet flow from a model nozzle. When expanding into a vacuum and/or a highly rarefied medium, the conditions for reproducing the relative gas pulse value of the full-scale nozzle block section are met. It is shown that when using specific similarity criteria, it is possible to experimentally model the supersonic jet outflow processes of space vehicles on small-sized laboratory vacuum installations, similar to the one created at Novosibirsk State University. Simulation results using spectral density measurements based on the glow excited by a focused electron beam, longitudinal and transverse jet density profiles obtained using modern scanning technology, as well as measurements of bottom pressure near the nozzle block are given. The possibilities and features of each applied registration method are discussed.
Linear thermal expansion coefficient of porous stainless steel
Authors: Kozlovskii Yu M , Stankus S V , Igumenov I K 
Published: December 2020

Abstract
The experimental results of the thermal expansion study of porous steel 12KH18N9TL in the temperature range 293–1173 K are presented. An anomalous change in the linear thermal expansion coefficient is found in the vicinity of 550 K. The temperature dependences of the thermal properties before and after heat treatment sre obtained and reference tables of recommended values are calculated.
Measuring the diffusion coefficient of single-wall carbon nanotubes in liquids
Authors: Rudyak V Ya , Tretiakov D S 
Published: December 2020

Abstract
This work is devoted to the experimental study of the diffusion of single-walled carbon nanotubes in liquids. The mass concentration of nanotubes varied from 0.00001 to 0.15. As the base fluid, water is used with the addition of two different surfactants: polyvinylpyrroli-done and sodium dodecylbenzenesulfonate. The concentration of surfactant is two times the concentration of nanotubes. The measurements are performed using the dynamic light scattering method. The diffusion and sizes of surfactant molecules have been preliminary studied. The diffusion coefficient of carbon nanotubes are investigated. Using these data the size distributions of nanotubes are obtained. The dependence of diffusion coefficients on the concentration of carbon nanotubes is examined.
Studying in-vessel component materials under heat and plasma loads relevant to fusion installations
Authors: Dedov A V , Budaev V P , Komov A T , Fedorovich S D , Varava A N , Zakharenkov A V , Karpov A V 
Published: December 2020

Abstract
The results of studies of materials under extreme thermal and plasma-beam loads, carried out to justify existing technological solutions in the design of thermonuclear reactors, are presented. The study of materials under plasma and beam loads and the intensifying heat transfer of in-vessel cooled components of fusion devices is reported. Tests of limiter and divertor mock-ups irradiated with high heat fluxes in electron beam and plasma facilities are described. Methods for cooling in-vessel components using advanced approaches with dispersed gas-liquid flow for heat removal, including at loads of up to 15 MW/m2 have been developed and tested.
Experimental study of dissociation of double gas hydrate at various combustion methods
Authors: Morozov V S 
Published: December 2020

Abstract
The dissociation during combustion of a propane-methane gas hydrate double powder is experimentally investigated. Gas hydrate combustion is implemented in four ways: 1) induction heating; 2) radiation and convective heating in a muffle furnace; 3) combustion without forced gas flow; and 4) combustion in the presence of forced air convection u
a. The maximum J is achieved by burning granules of gas hydrate powder on a metal surface with induction heating, where J is the specific dissociation rate. The minimum of J corresponds to the combustion of a layer of gas hydrate powder in the absence of forced air flow. With an increase in the velocity air convection u
a from 0 to 1.2 m/s the J increases and reaches a maximum. A further increase in u
a leads to a decrease in J. For u
a > 3.5 m/s combustion does not occur.
Development of the algorithm for the optimization of objects pick up sequence on a conveyor belt
Authors: Seredkin A V , Bobrov M S , Tokarev M P , Gobyzov O A 
Published: December 2020

Abstract
With recent advances in robotics, various methods and systems for robotic movement planning have gained popularity. In particular, the problem of planning of pick and move operations for the robotic sorting cells has drawn certain attention because new strategies and algorithms become a necessity as a robotic sorting systems application area extends. In the present work, a new algorithm for optimization of sorting operation sequences is proposed and results of its testing on a computer simulation are presented. The algorithm is based on the state tree search method and is aimed for performance improvement of the systems in which the input load can exceed the capacity of the robotic manipulator.
The Study of Self-Heating Effect of AlGaN/GaN High Electron Mobility Transistors Based on TCAD
Authors: Fang Zhicheng 
Published: December 2020

Abstract
As the third-generation semiconductor material, GaN has the characteristics of large forbidden band width and high electron mobility. The AlGaN/GaN high electron mobility transistors (HEMTs) have also attracted attention in recent years. In this paper, the effect of self-heating on device degradation was explored through theoretical analysis and software simulation. Firstly, Silvaco TCAD was used to establish an AlGaN/GaN HEMT single heterojunction model. Then, its self-heating effect was explored by simulation. Besides, it was compared with the theoretical analysis results. The control experiment method was used to compare the I-V output characteristic curve of the device when the self-heating effect was considered, and the relationship between the lattice temperature and the device degradation was researched. According to the research result, when the device is affected by the self-heating effect, the electrical performance of the device degrades obviously due to the increase of lattice temperature.
Research Progress of Gold Core-shell Structured Nanoparticles in Tumor Therapy
Authors: Zhang Ziyan 
Published: December 2020

Abstract
In previous research, the role of gold nanoparticles in tumor photothermal therapy and radiotherapy has attracted the attention of researchers. However, its limited photothermal conversion efficiency and inevitable biological toxicity restrict its further application. With the development of the field of nanomaterials, researchers have discovered that combining gold into core-shell structured nanomaterials can exhibit many surprising properties and has great potential in the field of tumor therapy. This article systematically reviews the progress of gold core-shell structured nanomaterials in the field of tumor therapy in recent years. In this paper, the progress of gold-core-shell nanomaterials in the field of cancer treatment in recent years is reviewed systematically, and the characteristics, preparation methods and deficiencies of gold core-shell nanoparticles are introduced respectively. Although gold core-shell nanoparticles have a good application prospect due to their low toxicity and good biocompatibility, a lot of research work is still needed to solve the problems such as aggregation, photothermal conversion efficiency and large-scale production.
A New Magnetic levitation System for Pipeline Inspection
Authors: Wang Ao , Zhang Yan 
Published: December 2020

Abstract
Through simulation design and simulation calculation, a new magnetic suspension system for pipeline detection is proposed. The system is convenient to carry pipeline detection device and realize the detection of pipeline interior. In this paper, the theoretical principle of the system is discussed, the model is simulated by using the simulation software, and the control method of the system is analyzed theoretically.
The Effect of Bionic Brake Drum Point Unit Body on Friction and Wear of Brake Pad
Authors: Hu Haiyan , Yang Haiyang , Yang Jiandong , Wang Qingnian , Zhou Ti 
Published: December 2020

Abstract
In this paper, the elasticity theoretical analysis has been used to analyze the interaction between the point unit body on the bionic brake drum and the brake pad. Through the analysis, the contact stress distribution law of their interaction has been obtained, and the change in friction and wear of brake pad based on the point unit body is calculated according to the stress distribution law. Only considering the change of the surface feature regardless of other factors, the friction and wear of the point unit body on the brake pad has increased by more than 50%. Based on the research, it is indicated that the small convex point unit bodies are added on the surface of the bionic brake drum, which make the contact surface between the brake drum and the brake pad no longer the original plane contact, and the pressure and direction between the contact surfaces are different. In addition, even if the external pressure remains unchanged, the contact pressure between two surfaces will be increased, thereby increasing the friction and wear of the brake pad.
Numerical and experimental study of buckling behavior of a composite hat-stiffened panel under in-plane shear
Authors: Sun Zhenya , Lei Zhenkun , Bai Ruixiang , Zhang Cong 
Published: December 2020

Abstract
The in-plane shear buckling behavior of a composite hat-stiffened panel is studied by the combination of experimental and numerical analysis. The buckling morphology changes of the hat-stiffened panel during in-plane shearing were monitored and measured by using the fringe projection profilometry and 3D digital image correlation. The in-plane shear buckling load, buckling modes, and failure load of the hat-stiffened composite panel were predicted by using the finite element numerical simulation. The buckling evolution process and failure mechanism of the composite hat-stiffened panel under in-plane shear can be effectively revealed by numerical and experimental investigation.
A distinct sub-seasonal modulation in the Atlantic-originated atmospheric teleconnection influence on East Asian monthly climates
Authors: Ham Yoo-Geun , Lee Se-Gun , Sung Mi-Kyung 
Published: December 2020

Abstract
The strong sub-seasonal modulation in the atmospheric teleconnection between the North Atlantic and East Asia during boreal winter has been examined. Negative precipitation anomalies and corresponding transient eddy vorticity fluxes over the mid-latitude Atlantic induce a wave packet that leads to cold temperatures over northern China, Korea, and Japan. This relationship is significant for the anomalies averaged from mid-January to mid-February, while it is less for January or February. In mid-January segment, the transient vorticity forcing (TVF) over the mid- to high-latitude Atlantic is the strongest, and consequently, the atmospheric response strengthens the anticyclone over central Eurasia to facilitate strong development of the Siberian High as well as cold temperatures in East Asia. Model simulations support the sub-seasonal linkage modulation through amplitude change of the TVF. It is proposed that intensified atmospheric baroclinicity associated with the deepened North American trough is responsible for the pronounced TVF and downstream influences in mid-January.
Theoretical analysis of fracture in non-linear elastic functionally graded beam of linearly changing thickness with three longitudinal cracks
Authors: Rizov V 
Published: December 2020

Abstract
The present paper is focussed on fracture analysis of a functionally graded nonlinear elastic cantilever beam structure with three longitudinal cracks. The cross-section of the beam is a rectangle. The beam height increases linearly towards the clamped end. The material is functionally graded along the thickness of the beam. The J-integral approach is applied in the fracture analysis. The solutions to the J-integral for the three cracks are verified by deriving of the strain energy release rate. For this purpose, the complementary strain energy cumulated in the beam is differentiated with respect to the areas of the three cracks. A parametric investigation of the longitudinal fracture behaviour of the beam is carried-out by applying the solutions to the J-integral. The effects of the beam geometry, the crack length and the material gradient along the beam thickness on the longitudinal fracture behaviour are evaluated and discussed.
Simulation of steel rod atmospheric corrosion by alternate immersion in salt solution
Authors: Tsonev Veselin , Nikolov Nikolay , Penkov Kamen , Marcheva Yordanka 
Published: December 2020

Abstract
Corroded B235 reinforcing steel rods, which were exposed to an open air environment for 25 years, with a certain specific mass loss, were studied. Test pieces were prepared from them by lathe machining. The test pieces were subjected to accelerated corrosion through an alternate immersion in NaCl solution. The same specific mass loss as on the initial corroded rods was achieved for 52 days. Further the test pieces were cleaned, observed, photographed and tensile tested. The cleaned surfaces and the stress-strain curves of the test pieces were compared with results, obtained from the initial corroded rods. It was found out about the tested steel rods that alternate immersion in salt solution for 52 days is a good simulation of twenty-five-year atmospheric corrosion.
Increasing the safety operation of railway tanks in emergency situations by improving the design of boiler bottom protective elements
Authors: Št’astniak Pavol , Gerlici Juraj , Kravchenko Kateryna 
Published: December 2020

Abstract
This article presents an analysis of the problem of reliability of tank boilers in an emergency event. The designs of the boiler bottom protection and the prevention of wagon crawls on top of each other in collisions are evaluated. An analysis of the requirements for the tank protective elements is performed. A technical solution to improve the protective shield of the bottom is developed. The proposed solution will increase rigidity and strength of the protective shield structure, reduce the risk of damage to the railway tank boiler bottom when the protruding elements of the adjacent wagon collide. The work presents the results of the stressstrain state of the proposed design protective shield in the case of rail car collision and, accordingly, the force impact of 150 kN according to the RID TE25 standard.
Research into the dynamic loading on the carrying structure of a flat wagon with lower center of gravity when transporting firing equipment
Authors: Fomin O , Lovska A , Pavliuchenkov M , Sova S 
Published: December 2020

Abstract
The article presents the study results of the dynamic loading of a flat wagon with a lower gravity center.The authors built a mathematical model that takes into account displacements of a flat wagon loaded with an anti-aircraft installation firing in motion. The solution of the differential equations of motion is carried out by using the Runge-Kutta method. The maximum vertical acceleration was about 5 m/sec2 and almost independent of the fire angle. The horizontal acceleration was about 37 m/sec2. The acceleration values obtained did not exceed the normative ones. The study defined the natural oscillation frequencies for the frame of a flat wagon with lower gravity center. It was established that the critical oscillation frequencies were within the admissible values. The results of the work will contribute to the creation of recommendations on the transportation of military equipment on wagons and the possibility of conducting military operations from them.
Numerical investigation of the mechanical behaviour of a structural element containing a self-healing agent
Authors: Zhelyazov T , Ivanov R 
Published: December 2020

Abstract
This paper presents a virtual experiment on the behaviour of a self-healing material from the family of cement-based composites, that contains a healing agent. A numerical model of a specimen made of a cement-based material, and containing a healing agent is subjected to the loading configuration of the four-point bending test, whereby the forces are applied in a quasi-static way. The response of the healed specimen is compared to the response of a specimen that doesn’t contain a healing agent. For the specimen that contains a healing agent, homogenization techniques are used to determine the characteristics of the equivalent material (cement-based composite / healing agent) in zones where damage and macro-cracking have occurred, i.e., zones in which the healing agent has been activated. The main result of this contribution is the formulation and validation of a numerical simulation approach suitable for modelling the mechanical behaviour of self-healing cement-based composites.
Study of hydrogen gaseous fuel influence on the thermal condition of a diesel engine
Authors: Dimitrov E , Peychev M , Michaylov Ph , Pantchev S 
Published: December 2020

Abstract
The current article presents experimental results for the thermal condition of a diesel-hydrogen powered engine. The object of the study is an air-cooled single cylinder diesel engine. A quantitative assessment of the engine thermal condition is made. It is based on four engine body part temperatures and the temperatures of exhaust gases and engine oil. The study is carried through by comparing the engine indexes via regulation characteristics as a function of the hydrogen mass content and load characteristics with constant hydrogen content. Experimental results as a function of engine speed at constant engine power are also presented. The data registered during the experiment is for two different diesel injection advance angles. A temperature for one location on the combustion chamber roof (cylinder head) is calculated. The results of the experiment are presented in charts.
Fuel cell electric vehicles. Investigation of the energy balance for optimal reforming process of bio-ethanol
Authors: Dimitrova Zlatina 
Published: December 2020

Abstract
Hydrogen ecosystem and hydrogen economy are relevant topics for the mobility. This article summarizes the ways of production of “green” hydrogen. The hydrogen storage and transportation are discussed as well. The article presents the concept of electric vehicle with serial range extender to extend the vehicle autonomy. Fuel cell system powered by hydrogen produced through reforming of liquid fuel from renewable resources such as bioethanol is considered as a range extender module. Alkaline fuel cell and solid oxide fuel cell are investigated for the use of a variety of liquid fuels instead of traditionally used hydrogen in others types of fuel cells. This article investigates the energy balance of the different types of fuel cells, powered by bio-ethanol. Three variants for ethanol conversion are investigated: variant 1 : reforming of bio-ethanol in external reformer to hydrogen and its conversion in alkaline fuel cell, variant 2: reforming of bio-ethanol in external reformer to hydrogen and its conversion in a solid oxide fuel cell; variant 3 : direct reforming of the bio-ethanol in the solid oxide fuel cell. The chemical processes for each variant are proposed and thermodynamic energy balance is calculated. From the results is visible that the most efficient configuration is the variant 3, the direct reforming of the bio-ethanol by the solid oxide fuel cell. The variant 3 delivers 15 MJ of energy output per kilogram of bio-ethanol, used in the fuel cell.
Energy demand assessment for long term operation of hybrid electric vehicles
Authors: Sitnik Lech J , Ivanov Zdravko D , Sroka Zbigniew J 
Published: December 2020

Abstract
This publication deals with the assessment of fuel demand for long-term operation of hybrid vehicles, because only with this kind of analysis it could be possible to clearly and unequivocally assess the actual progress in achieving the intended goals. The long-term test is the opposite of short-term tests - currently WLTP and RDE or other tests developed mostly by specialized magazines. Long-term car use means mileage measured in thousands of kilometers over a period of several years. The assessment of fuel consumption during long-term operation of HEVs from the presented point of view is new, in which the theory of demand for cumulated energy (as fuel) proved to be very useful. Mathematical models of fuel consumption along with an assessment of its intensity and a description of fuel economy constitute the vehicle’s “energy footprint”. Cumulative fuel consumption increases as mileage increases, but the increase is not a linear function. The discrepancy between fuel consumption in a group of vehicles of the same make and type is significant and increases as mileage increases. The average fuel consumption of the analyzed HEVs during their long-term operation significantly exceeds what is determined by the short tests, e.g. WLTP (and earlier NEDC). The actual fuel consumption is much higher than the one from the short tests.