bluuebunny/crossref_metadata_2025 huggingface dataset:
A modular X-pinch device for versatile X-pinch experiments at Seoul National University
Authors: Ryu Jonghyeon , Ham Seunggi , Lee Juhyeong , Park JongYoon , Park Sungbin , Choi YeongHwan , Woo H. J. , Lee Kern , Ghim Y.-C. , Hwang Y. S. , Chung Kyoung-Jae
Published: May 2021

This paper describes an X-pinch device recently developed at Seoul National University (SNU). The SNU X-pinch device is designed and fabricated to accommodate various diagnostics as well as conduct versatile experiments. It is easy to change the capacitance of the pulse generator because the capacitor bank has a modular design without insulation oil or gas. This allows us to perform a variety of experiments with a wide capacitance range from 80 to 800 nF. The operating voltage of the SNU X-pinch device is controlled from 20 to 100 kV by adjusting the gas pressure inside a triggered spark-gap switch. Triggering of the spark-gap switch is synchronized with the operation of a pulsed laser to diagnose the X-pinch plasma at the proper time. A large vacuum chamber precisely machined from an aluminum mono-block is attached to the top of the pulse generator. It is designed to accommodate not only various X-pinch loads but also various diagnostic apparatus such as optical components. Initial experiments with the SNU X-pinch device have successfully generated x rays with wires of various materials and sizes. The device will be used not only to explore the dynamics of X-pinch plasmas but also as a test stand for diagnostics of high-energy-density plasmas.
Finite gyroradius multidimensional electron hole equilibria
Authors: Hutchinson I. H.
Published: May 2021

Finite electron gyroradius influences on the trapping and charge density distribution of electron holes of limited transverse extent are calculated analytically and explored by numerical orbit integration in low to moderate magnetic fields. Parallel trapping is shown to depend upon the gyroaveraged potential energy and to give rise to gyroaveraged charge deficit. Both types of average are expressible as convolutions with perpendicular Gaussians of width equal to the thermal gyroradius. Orbit-following confirms these phenomena but also confirms for the first time in self-consistent potential profiles the importance of gyrobounce resonance detrapping and consequent velocity diffusion on stochastic orbits. The averaging strongly reduces the trapped electron deficit that can be sustained by any potential profile whose transverse width is comparable to the gyroradius rg. It effectively prevents equilibrium widths smaller than ∼rg for times longer than a quarter parallel-bounce-period. Avoiding gyrobounce resonance detrapping is even more restrictive, except for very small potential amplitudes, but it takes multiple bounce periods to act. Quantitative criteria are given for both types of orbit loss.
Epitaxial stannate pyrochlore thin films: Limitations of cation stoichiometry and electron doping
Authors: Hensling Felix V. E. , Dahliah Diana , Dulal Prabin , Singleton Patrick , Sun Jiaxin , Schubert Jürgen , Paik Hanjong , Subedi Indra , Subedi Biwas , Rignanese Gian-Marco , Podraza Nikolas J. , Hautier Geoffroy , Schlom Darrell G.
Published: May 2021

We have studied the growth of epitaxial films of stannate pyrochlores with a general formula A2Sn2O7 (A = La and Y) and find that it is possible to incorporate ∼25% excess of the A-site constituent; in contrast, any tin excess is expelled. We unravel the defect chemistry, allowing for the incorporation of excess A-site species and the mechanism behind the tin expulsion. An A-site surplus is manifested by a shift in the film diffraction peaks, and the expulsion of tin is apparent from the surface morphology of the film. In an attempt to increase La2Sn2O7 conductivity through n-type doping, substantial quantities of tin have been substituted by antimony while maintaining good film quality. The sample remained insulating as explained by first-principles computations, showing that both the oxygen vacancy and antimony-on-tin substitutional defects are deep. Similar conclusions are drawn on Y2Sn2O7. An alternative n-type dopant, fluorine on oxygen, is shallow according to computations and more likely to lead to electrical conductivity. The bandgaps of stoichiometric La2Sn2O7 and Y2Sn2O7 films were determined by spectroscopic ellipsometry to be 4.2 eV and 4.48 eV, respectively.
The effect of three-phase contact line pinning during the passage of an isolated bubble through a confining pore
Authors: Ansari Shadi , Nobes David. S.
Published: May 2021

The change in the internal pressure of an isolated dispersed phase passing through a confined geometry can be determined by tracking its deformation. While some research has been carried out on the motion of the dispersed phase, these have mostly focused on the calculation of the critical pressure required for the phase to enter the confined geometry and did not account for the variation of pressure across the phase as it passes through a confined geometry. In the current study, an algorithm based on the shadowgraph method was developed to evaluate the instantaneous change in the pressure of an isolated bubble passing through a confined geometry. The result of the study showed that the pressure across the bubble varies at different locations along the pore. The critical pressure was determined by detecting the change in pressure introduced at the entrance of the pore geometry. The results showed that the critical pressure increases as the size of the bubble increases. Phase pinning introduced a significant pressure change across the bubble as it exits the pore, resulting in significant deceleration of the bubble. The results of different sizes of bubbles passing through the same geometry showed that the pinning of the phase intensifies as the bubble size increases. The present study confirms the significance of the interaction of the solid interface and the dispersed phase on the motion of two immiscible flows in a confined geometry.
On defining functions and cores for unbounded domains. III
Authors: Harz T. , Shcherbina N. , Tomassini G.
Published: May 2021

We extend the authors’ results on existence of global defining functions to a number of different settings. In particular, we relax the assumption on strict pseudoconvexity of the domain to strict

-pseudoconvexity and we consider more general situations, where the ambient space is an almost complex manifold or a complex space. We also investigate to what extent the assumption on smoothness of the boundary of the domains under consideration is necessary in our results.

Bibliography: 27 titles.
Quadrupolar charge dynamics in the nonmagnetic FeSe

1−
x

S

x

superconductors
Authors: Zhang Weilu , Wu Shangfei , Kasahara Shigeru , Shibauchi Takasada , Matsuda Yuji , Blumberg Girsh
Published: May 2021

Significance

The family of iron selenide (FeSe) superconductors is of great interest because it harbors an unusual nonmagnetic nematic state, exhibits a peculiar orbital-selective Cooper pairing, and has a strong potential for high-temperature superconductivity. Here, for

F
e
S
e

1
−
x

S

x

nonmagnetic metal, we report discovery of a pseudogap in the spectra of electronic long-wavelength charge quadrupole excitation below the nematic phase transition with temperature dependence of the gap’s magnitude reminiscent of a nematic order parameter. We argue that the intense continuum of excitations in the high-temperature phase with tetragonal symmetry arises due to non-Fermi liquid dynamics governed by Pomeranchuk fluctuations and that these fluctuations are suppressed in the symmetry-broken orthorhombic low-temperature phase, enabling the recovery of Fermi liquid properties.
Subsystem macroarchitecture of the intrinsic midbrain neural network and its tectal and tegmental subnetworks
Authors: Swanson Larry W. , Hahn Joel D. , Sporns Olaf
Published: May 2021

Significance

The midbrain is one of the vertebrate brain’s three basic divisions, and it plays an especially important role in sensory–motor mechanisms, motivation and reward, reproductive and agonistic behaviors, and behavioral state. Network science methods were applied here to reveal organizing principles of intramidbrain circuitry, which include a hierarchy of subsystems that was used to construct a structure–function model of the circuitry. The results show fundamental differences between intramidbrain and previously determined intraforebrain network organization and provide a theoretical framework for experimental analysis of intramidbrain circuit involvement in specific behaviors.
Comparative anatomy and physiology.
Authors: Rees Paul A.
Published: May 2021

This chapter contains questions concerned with the basic principles of anatomy and physiology in living things and the differences between, and similarities within, taxa with respect to their anatomical and physiological characteristics.
Seed-bearing plants.
Authors: Rees Paul A.
Published: May 2021

This chapter contains questions about the classification, evolution and characteristics of seed-bearing plants (angiosperms and gymnosperms). The questions are divided into three levels: foundation, intermediate and advanced.
Arthropods and echinoderms.
Authors: Rees Paul A.
Published: May 2021

This chapter contains questions on the classification, anatomy and characteristics of the Arthropoda and Echinodermata. The questions are divided into three levels, i.e. foundation, intermediate, and advanced. Knowledge of basic facts are dealt with at the foundation level while the intermediate level and advanced levels contain questions involving more obscure facts and concepts.
Mimosa pigra (giant sensitive plant).
Authors: Rojas-Sandoval Julissa , Acevedo-Rodríguez Pedro
Published: May 2021

M. pigra is a small prickly shrub that infests wetlands and is also an agricultural weed in rice fields in many parts of the old world tropics. In natural wetlands the shrub alters open grasslands into dense thorny thickets and negatively impacts on native biodiversity. It is regarded as one of the worst alien invasive weeds of wetlands of tropical Africa, Asia and Australia, and the cost of control is often high.
The effect of laser irradiation on reducing the noise of solid-state nanopore
Authors: Liang Shengfa , Zhang Wenchang , Xiang Feibin
Published: May 2021

The performance of solid-state nanopore is affected by the noise level. This study aimed to investigate the effect of laser irradiation on the noise performance of solid-state nanopore in situ. Laser irradiation is applied to fresh and contaminated nanopores. The measurement results show that the noise of fresh and contaminated nanopores decreases with the laser power and there is a threshold of laser power in reducing the noise of contaminated nanopores. The possible reasons for reducing noise in the laser irradiation process are discussed. The laser treatment is proven to provide a convenient method for reducing the noise of solid-state nanopore.
Some properties of circle maps with zero topological entropy
Authors: Yang Yini
Published: May 2021

In this paper we introduce three pairs in ‘local entropy theory’. For a dynamical system (X, f), a pair

x
,
y

∈
X
×
X

is called an IN-pair (reps. an IT-pair) if for any neighborhoods U
1 and U
2 of x and y respectively,

U

1

,

U

2

has arbitrarily large finite independence sets (reps.

U

1

,

U

2

has an infinite independence set) where

I
⊂
N

is called an independence set of

A

1

,

A

2

,
…
,

A

k

if for any non-empty finite subset J of I and S ∈ {1, 2, …, k}
J
, ⋂
i∈J

f
−i

A

S(i) ≠ ∅. For a circle map or interval map (M, f), a pair ⟨x, y⟩ ∈ M × M with x ≠ y is called non-separable if there exists z ∈ M such that x, y ∈ ω(z, f) and ⟨x, y⟩ can not be separated. For a circle map

f
:
S
→
S

with zero topological entropy, we show that a non-diagonal pair

⟨

x
,
y

⟩

∈
S
×
S

is non-separable if and only if it is an IN-pair if and only if it is an IT-pair. We introduce the maximal pattern entropy and recall that a null system is a system with zero maximal pattern entropy. We also show that if a circle map is topological null then the maximal pattern entropy of every open cover is of polynomial order.
Sufficient conditions for local scaling laws for stationary martingale solutions to the 3D Navier–Stokes equations
Authors: Papathanasiou Stavros
Published: May 2021

The main goal of this paper is to obtain sufficient conditions that allow us to rigorously derive local versions of the 4/5 and 4/3 laws of hydrodynamic turbulence, by which we mean versions of these laws that hold in bounded domains. This is done in the context of stationary martingale solutions of the Navier–Stokes equations driven by an Ornstein–Uhlenbeck process. Specifically, we show that under an assumption of ‘on average’ precompactness in L
3, the local structure functions are expressed up to first order in the length scale as nonlinear fluxes, in the vanishing viscosity limit and within an appropriate range of scales. If in addition one assumes local energy equality, this is equivalent to expressing the structure functions in terms of the local dissipation. Our precompactness assumption is also shown to produce stationary martingale solutions of the Euler equations with the same type of forcing in the vanishing viscosity limit.
Stability and Hopf bifurcation analysis in a Lotka–Volterra competition–diffusion–advection model with time delay effect
*
Authors: Li Zhenzhen , Dai Binxiang
Published: May 2021

In this paper, we consider a classical two-species Lotka–Volterra competition–diffusion–advection model with time delay effect. By utilizing the implicit function theorem, we obtain the existence of at least one spatially nonhomogeneous positive steady state under some conditions on parameters. By analyzing the corresponding characteristic equation, we show the local stability of this spatially nonhomogeneous positive steady state and the occurrence of Hopf bifurcation from it. When there is no time delay, we also study the global stability of the positive steady state. Based on the idea of Chen et al (2018 J. Differ. Equ.
264 5333–5359), the stability and direction of Hopf bifurcation are derived by introducing a weighted inner product associated with the advection rate. Finally, numerical simulations are carried out to verify the theoretical analysis results.
Linear response for the dynamic Laplacian and finite-time coherent sets
Authors: Antown Fadi , Froyland Gary , Junge Oliver
Published: May 2021

Finite-time coherent sets represent minimally mixing objects in general nonlinear dynamics, and are spatially mobile features that are the most predictable in the medium term. When the dynamical system is subjected to small parameter change, one can ask about the rate of change of (i) the location and shape of the coherent sets, and (ii) the mixing properties (how much more or less mixing), with respect to the parameter. We answer these questions by developing linear response theory for the eigenfunctions of the dynamic Laplace operator, from which one readily obtains the linear response of the corresponding coherent sets. We construct efficient numerical methods based on a recent finite-element approach and provide numerical examples.
Design of phoxonic filter using locally-resonant cavities
Authors: Aboutalebi Seyedeh Zahra , Bahrami Ali
Published: May 2021

A phoxonic crystal structure with a full phononic and photonic band gap is designed in this study, which is capable of conducting sound waves and also light waves with transverse magnetic (TM) polarization. Materials used in the structures are nylon and molybdenum, both of which have adequate difference in refractive index and elastic constants. It is worth of noting that the filling factor is considered to be 28% in all of the structures, in order to ease of fabrication. The final phoxonic filter structure is obtained by the comparison of several phoxonic filter structures in a similar condition. Since it is difficult to coordinate light and sound in phoxonic structures, the proposed structure has some advantages compared to other filters. This structure shows the optical and acoustical transmission linewidths equal 3.8 KHz in phononic and 0.06 nm in photonic modes, respectively. Also, the output quality factor is 23699 in phononic and 21201 in photonic modes. Finite element, plane wave expansion, and finite-difference time-domain methods are utilized for simulation.
Non-isothermal flow of Sisko fluid in a stenotic tube induced via pulsatile pressure gradient and periodic body acceleration
Authors: Fahim M , Sajid M , Ali N
Published: May 2021

A theoretical study for pulsatile unsteady blood flow and heat transfer effects via tapered stenotic artery is presented. This study is based upon a non-Newtonian Sisko-fluid model. The order of magnitude analysis is executed for the derivation of momentum and energy equations for the mild constriction model. The coordinate transformation is utilized to transform the computational domain. A finite difference scheme is utilized for the solution of modeled non-linear partial differential equations. The computed results are exhibited in form of graphs for velocity, wall shear stress (WSS), resistive impendence, flow rate, and temperature for appropriate ranges of important physical parameters governing the flow, including the Sisko fluid material parameter

0.1
≤
ϵ
≤
1.5

,

power-law index

0.7
≤
n
≤
1.5

,

stenosis height

0
≤
δ
≤
0.4

,

the amplitude of body acceleration

0
≤

B

2

≤
2

,

shape parameter

2
≤
m
≤
15

,

Prandtl number

10
≤
P
r
≤
20

,

and Brinkman number

2
≤
B
r
≤
6

.

This investigation deduces that the flow rate and blood velocity rise with the escalation in the amplitude of body acceleration and shape parameter whereas both decrease by varying material parameter, power-law index, and stenosis height. The wall shear stress (WSS) rises with increasing the power-law index, material parameter, and stenosis height, whereas it decreases with the escalation in the amplitude of body acceleration and shape parameter. The resistive impedance increases with the increase of the size of stenosis and power-law index. The temperature field appears to dominate for smaller values of Prandtl number and larger values of Brinkman number.
Significance of increasing Lorentz force and buoyancy force on the dynamics of water conveying SWCNT and MWCNT nanoparticles through a vertical microchannel
Authors: Ramesh G K , Manohar G R , Venkatesh P , Gireesha B J
Published: May 2021

Carbon nanotubes are used to achieve high heat transfer rates in a variety of engineering applications include thermal storage systems, electronic component cooling, high-performance building insulation, heat exchangers and drying technologies. Hence the aim of this article is to examine the addition of single walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) to water in a vertical microchannel to improve heat transfer. The effects of MHD, slip, convective boundary condition and heat source/sink are incorporated. The Brinkman-Forchheimer flow model and type II hybrid nanofluid model is adopted. Converted dimensionless differential equations are solved numerically via Dsolve command with the aid of Maple. The simulation assessment is worked out by graphs. One of the main tasks of the analysis is to compare MWCNT/water and SWCNT-MWCNT/water. It is shown that the improvement of the heat source/sink parameter improves the temperature and the rate of heat transfer in MWCNT/water is higher than SWCNT-MWCNT/water. Also larger values of Lorentz force and buoyancy force decreases the drag coefficient.
Multi-transonic spherical-type flows around massive black holes: galactic potential induced standing isothermal shocks
Authors: Raychaudhuri Sananda , Ghosh Shubhrangshu , Joarder Partha S.
Published: May 2021

Accretion on length-scales of interstellar or even intergalactic is particularly relevant, in the context of spherical or quasi-spherical hot mode accretion, supposedly powering low excitation radio galaxies in the maintenance-mode feedback paradigm. In the present study, we aim to analyze such a spherical-type flow around the host active nucleus in the backdrop of a five-component galactic system (SMBH, stellar, dark matter, diffuse hot gas, Λ), with the principal intent to address the issue of galactic potential induced shock formation in the flow, that may contain (dissipative) isothermal standing shocks. The present paper is an extension of Raychaudhuri et al. (2018) [83], who conducted a preliminary investigation of such a problem. The galactic potential, not only renders the flow to be multi-transonic in nature, the flow topology resembles `Xα' and `α X' type trajectories of advective flows in the vicinity of the BHs/compact objects. Owing to the influence of the galactic potential, the entire range of galactic mass-to-light ratio (ΥB) allows shock formation in central to the outer radial regions of our wind-type flows, with the strength of those galactic induced shocks found to be comparable to that of the shocks one would expect in the advective flows in the vicinity of a BH. We also observe that the shock parameters remain sensitive to ΥB. We discussed the possible implication of these shocks in the context of radio source dynamics as well as their potential association with flaring in radio jets. Our study also reveals that galactic potential could substantially augment the mass inflow rate.
Prospects of constraining reionization model parameters using Minkowski tensors and Betti numbers
Authors: Kapahtia Akanksha , Chingangbam Pravabati , Ghara Raghunath , Appleby Stephen , Choudhury Tirthankar Roy
Published: May 2021

We explore the possibility of constraining model parameters of the Epoch of Reionization (EoR) from 21cm brightness temperature maps, using a combination of morphological descriptors constructed from the eigenvalues of the Contour Minkowski Tensor (CMT), Betti numbers (count of connected regions ncon and holes nhole) and the area of structures in the excursion set of the field. We use a three parameter model of EoR simulated using 21cmFAST, namely the ionizing efficiency of sources ζ, the minimum virial temperature Tvir required for collapse into a halo and the maximum radius for ionizing radiation described by Rmfp. We performed a Bayesian analysis to recover model parameters for a mock 21cm image from SKA phase I at a redshift of z=7.4 corresponding to a mean neutral hydrogen fraction of x̅HI≃ 0.5. We find that in the absence of noise the average size of structures in the field with xHI≲ 0.5 is smaller than regions with xHI≳ 0.5 and the structures are equally isotropic when x̅HI=0.5 . We also find that in order to recover the input model to within 1-σ accuracy for a mock noisy image at a single frequency channel of 1 MHz, for an observation time t_obs<2000 hrs, the noisy δ Tb map needs to be smoothed at a scale R_s>9.5 Mpc. Finally we show that the systematic behaviour of the statistic as ionization progresses, enables us to obtain stringent constraints on x̅HI (with a coefficient of variation ∼ 0.05 as compared to ∼ 0.1–0.2 for model parameter constraints), thereby making these descriptors a promising statistic for constraining EoR model parameters and the ionization history of the universe.
Developing an inverter controlling electric motor for small air transport
Authors: Zagumennov F A , Varyukhin A N , Kazakov A V , Zhuravlev D I , Zakharchenko V S , Ivanov G.S.
Published: May 2021

This paper provides a concept for developing inverters for high power aircraft brushless motors. It should be noted that such devices have an increased number of safety solutions, stable rotor synchronization parameters, and an increased number of isolated hardware nodes. The main result of this study is an engine motor controller with a power of up to 60 kW with control through optical fiber, liquid cooling, completely isolated power and control circuits, overcurrent, inverter and motor temperature protection, synchronization by Hall sensors. This paper also contains the calculation of the cost of introducing such solutions into a typical inverter.
A review of electrified propulsion system concepts for advanced aircraft
Authors: Ovdienko M A , Varyukhin A N , Zakharchenko V S , Vlasov A V
Published: May 2021

The active development of electrical technology provided leeway to creating fundamentally new configurations of propulsion systems and novel aerodynamic layouts of aircraft. Currently, this area of science is in the initial stage of development, but thanks to its huge potential, the number of projects with new propulsion system configurations is growing annually at an exponential rate. A classification of new types of propulsion system configurations is presented in order to understand its wide variety. Beneficial and negative impacts of each configuration are presented.
Research of the flat end gap’s clearance size influence on mechanical power losses in a centrifugal pump by hydrodynamic modeling methods
Authors: Kalinkin S , Petrov A
Published: May 2021

This article highlights the problems associated with calculating disk losses in pumping units. The paper addresses the problems of a theoretical description of the process of fluid flow in narrow end clearances. By varying several parameters of the system, the authors made attempts to identify the dependence of mechanical losses on the flow rate, rotor rotation frequency, the value of the clearance and the direction of the flow. The results of the research are given in a dimensionless form, based on which the corresponding conclusions are drawn.
Interaction of ethane with singlet oxygen: A theoretical study of potential energy surfaces
Authors: Pelevkin Alexey V. , Sharipov Alexander S.
Published: May 2021

A study of the C2H6+O2 reaction system was carried out using ab initio quantum chemistry methods. The main reaction and quenching channels were identified, corresponding activation energies were calculated, and the pathways of the minimum reaction energy were constructed. It was found that the reaction channels of ethane molecule with singlet delta oxygen proceed with a lower barrier than with the oxygen molecule in the ground state. The reaction of ethane with singlet sigma oxygen, in turn, proceeds through the dissociation of the O2 molecule; however, the quenching channel is still possible because of the intersystem crossings. Based on the obtained data, the appropriate reactions rate constants can be estimated by using variational and nonadiabatic transition state theories.
Hydrodynamics of detachment, free falling and impact of drops
Authors: Chashechkin Yuli
Published: May 2021

The results of optical measurements of drop dynamics are presented. Oscillations and waves on its surface were traced. The pattern of the secondary droplets falls onto an immersed drop and the discrete distribution of the substance of a uniformly colored drop in the targeted liquid was visualized. The important role of energy transport processes, both fast – local atomic-molecular – and slow that are translational and dissipative, in the formation of flow patterns is highlighted. A system of fundamental equations of fluid mechanics with equations of state for the Gibbs potential and density is applied. Ligaments – thin trickles with scales from atomic-molecular and macroscopic sizes – are investigated. Their images in the family of intrinsic solutions of the fundamental system and drop impact phenomena are shown.
Relevance of mathematical modelling of textile fillers’ 3-D structures for composite materials reinforcement
Authors: Bazaev E M , Zaretskaya G P , Privalov A A , Lunina E V , Rudneva T V , Shanygin A N , Smotrova S A
Published: May 2021

This paper discusses current and promising areas in the field of solving the fundamental problem of mathematical modelling in the design of bulk structures of textile fillers, which largely depend on the strength and weight characteristics of elements of aircraft made of polymer composite materials (PCM). Examples of mathematical modelling results of an aircraft engine blade’s textile filler for PCM are given. The study was funded by RFBR, project number 19-29-13044.
The dimension indicator of the vibration signal for diagnosing gas turbine engines support bearings
Authors: Tyapkin S A
Published: May 2021

This paper showcases the results of a study on the correlation dimension of the vibration signal in cases of the destruction of aviation engines support bearings. The relevance of the study is determined by the search for promising solutions to improve the maintenance of aircraft engines. It is established that the correlation dimension of the vibration signal of working and defective bearings are contrast with a significance level of 0.002. The scientific significance of the research lies in the statistical substantiation of the application of the vibration signal dimension in gas turbine engines diagnosis systems.
Influence of operating time on the strength reliability of the gas generator turbine disk of the aircraft drive for the GPA
Authors: Velikanova N P , Protasova N A , Velikanov P G , Kiselev A S , Salih Salih Indad Shareef
Published: May 2021

This paper contains the analysis of characteristics changes of mechanical properties of the EI698-VD alloy depending on the duration of operation of the NK family gas turbine disks working as part of a gas generator turbine for GPA. Their stress-strain state was determined using the finite element method. The strength reserves are defined as characteristics of the disks’ strength reliability at different levels of the operating time.
An automated measuring complex of electromagnetic parameters of materials in the field of superhigh frequencies
Authors: Golentsov D , Flanden V , Solntseva M
Published: May 2021

This work is dedicated to the features of measuring the electromagnetic parameters of materials. In the field of superhigh frequencies, there are practically no documents regulating the requirements for the properties of materials and means for measuring the electromagnetic parameters of materials. To solve the problems of metrological support for this frequency range and new materials, several steps are required. One of them is the development of a measuring complex. This work describes the composition of the developed model of such a complex and its distinctive features. The text contains models of materials. The extended frequency ranges from 200 MHz to 80 GHz. The range of external magnetic fields has been expanded from 4 kA/m to 70 kA/m.
A study of the effect of electron-beam processing on the surface of samples obtained by additive technologies from cobalt-chromium powder
Authors: Dzhafarov E E , Erikov K M , Bytsenko O A
Published: May 2021

Products made of cobalt-chromium made by additive manufacturing methods are widely used in many branches of modern industry (aviation, mechanical engineering, shipbuilding and instrumentation, energy, medicine, etc.). Surface treatment with high-current pulsed electron beams (HPEB) is a promising method for further expanding the scope of these alloys. The article presents studies of the structural and phase state of the surface layer of samples before and after treatment with high-current pulsed electron beams.
Designing gears with minimal effective transmission error by optimizing the parameters of tooth modification
Authors: Dorofeev D V , Kalinin D V , Kozarinov E V
Published: May 2021

This paper is dedicated to the development of a method for optimizing the parameters of modification of gears. An experimental study of the effectiveness of the modification, calculated according to the current standard, has been carried out. Within the framework of the project, a software has been developed that implements an algorithm for designing three-dimensional models of gears with a modified topology of contacting side surfaces, which are used for the subsequent modeling by the finite element method of the process of teeth meshing. The results obtained were used to solve the one-criterion optimization problem. As an example of using the method, the optimization of the parameters of the modification of the teeth was carried out in order to minimize the amplitude of the transmission error harmonics.
Monitoring the state of power plants’ friction pairs on the basis of single-coil eddy-current sensors
Authors: Blinov A , Borovik S , Luchsheva M , Muhutdinov F , Sekisov Yu
Published: May 2021

The tasks of “on-line” assessment of the state of friction pairs of high-power power plants are considered. They are based on the use of clusters (groups) of original single-coil eddy-current sensors. It is proposed to use the information about the presence of wear particles in the lubrication system of the power plant and the axial displacement of the shaft in a radial thrust bearing as the main monitored parameters. A brief description of the methods for obtaining the information about the desired parameters and the tools that implement them is provided.
Influence of technological factors on porosity in the mass production of inlet guide vanes using additive technologies
Authors: Erikov K M , Dzhafarov E E , Bytsenko O A
Published: May 2021

Stainless steel products manufactured using additive technologies are widely used in many branches of modern industry (aviation, medicine, engineering, etc.). One of the main defects in this type of production is porosity. Surface treatment with high-current pulsed electron beams (HPEB) allows not only to increase microhardness and corrosion resistance, but also to reduce surface roughness and porosity in the recrystalized layer. This article presents studies of the microstructure of stainless steel samples, as well as the structural and phase state of the surface layer of samples before and after irradiation with HPEB.
Regularities of the high-temperature transformation of poly-2-methyl-5-vinyltetrazole and solid fuel compositions based on it in the nitrogen atmosphere
Authors: Volkova N N , Dashko D V , Zholudev A F , Kislov M B , Yanovskii L S
Published: May 2021

Macrokinetic regularities of high-temperature transformations of energy compositions based on poly-2-methyl-5-vinyltetrazole as an active binder have been studied. It has been shown that, in contrast to synthetic rubber, which is currently used in solid rocket fuel, poly-2-methyl-5-vinyltetrazole when added to the energy compositions based on high-nitrogen heterocycles leads to an increase in the burning rate of the fuel. The synergetic effect of the interaction between a binder and dispersant, manifested in an increase in the burning rate of the high-energy composition, reaches a maximum value when the mass ratio of the components in a binary mixture is 1:1.
Developing and testing a hybrid propulsion system demonstrator
Authors: Varyukhin A N , Zhuravlev D I , Zakharchenko V S , Geliev A V , Kiselev I O , Lomazov V S
Published: May 2021

This paper provides a description of a hybrid electric propulsion system demonstrator developed at CIAM. The key element of the demonstrator is an electric motor based on the principles of high-temperature superconductivity. Bench tests of several demonstrator units and devices have been successfully carried out. After their completion, bench tests of a full demonstrator were carried out in a high-altitude-climatic chamber.
Performance of CFD and ANN modeling of heat transfer enhancement in a circular tube with artificial roughness
Authors: Kuzmenkov N V , Frantcuzov M S , Koroleva A P
Published: May 2021

This paper presents a comparison of three different approaches for modeling enhanced heat transfer characteristics of turbulent airflow in a circular tube with artificial roughness of transverse ribs. A number of CFD simulations are carried out forming the first dataset as well as the second dataset extracted from a number of classical works. A deep feed-forward neural network is developed to predict Nusselt number and friction factor for a variety of rib roughness and flow parameters. The ANN is trained by the first dataset (the CFD and ANN approach) and the second dataset (the experiment and ANN approach) independently and by a combination of datasets (the hybrid approach) showing good quality predictions in all the cases. All results are compared with experimental data and CFD modelled values showing the best results of the experiment and ANN approach.
An Over-View Of The Applications Of Dfa (Design For Assembly) Techniques On Automobile Components For Reducing Assembly Time And Cost
Authors: Jaiswal Shrey Arvind , Darius Gnanaraj S
Published: May 2021

Design for Manufacturing and Assembly (DFMA) techniques are useful for minimizing the cost of products through design and process improvements. DFMA is a combination of Design for Manufacturing (DFM) and Design for Assembly (DFA). This paper focuses case studies on the successful application of DFA techniques on Automobile components and reports the reduction in assembly time and cost of the product successfully achieved by different R&D works carried out by researchers around the World, collected through literature survey. Information available related to the following topics are collected and analyzed: minimize part count, design parts with self-locating features, design parts with self-fastening features, minimize reorientation of parts during assembly, standardization of parts, minimum use of fasteners, modular design, design for a base part to locate other components and design for component symmetry for insertion. The findings reported in this over-view are useful to practicing design engineers.
Analysis Of Disc Brake
Authors: Barik Nishant , Razak Khadari Sayyad Abdul
Published: May 2021

his paper deals with the structural analysis of the rotor disc of disc brake. The rotor disc of a disc brake goes through many forces that are applied on it to stop the wheel. The deterioration of the disc brake is a major factor which should be kept in mind during a designing and choosing of the material of disc brake. The material properties are taken in context with the type of forces that act on the brake. In this paper all the disc brakes from past year few years have been analyzed and on the basis of that new model has been designed. The materials taken are compared and to see which shows the best result in the new model disc. The disc brake modelling in done on SOLIDWORKS followed by analysis in ANSYS WORKBENCH 18.1. The dimensions are taken with respect to the MOTOGP brakes
Design Optimization of Universal Joints for All-Terrain Vehicles
Authors: Yanda Sagar , Bala Murali Gunji , Shankar raju Siva , Jason Duckworth Bill , Sen Chandra , Singh Chadha Sidakdeep
Published: May 2021

Universal joint mechanism widely used in the automobile power transmission systems. This joint mechanism desired to permit some angular deviations along the axis of rotation. The cardan joint comprises of the three main parts including the input drive shaft, the output drive shaft and the cross like piece. Two points of the cross piece connect to the input drive shaft and two other points connect to the output drive shaft. Connections are provided by the needle bearings. It is an important aspect of these bearings that while in action they never go through complete cycles. In other words, each of these bearings revolves only a few degrees around its axis before returning to its original position. The paper aims to develop a UV joint that is suitable for All-Terrain Vehicles (ATVs). These types of vehicles have to traverse rough terrain and hence require taller suspension set up. Conventional universal joints limit this ability as the allowable articulation angle is very less. Due to this, they are prone to wear and malfunction and need to be replaced in comparatively short intervals of time. Naturally, it means that such parts have limited life span. We have hence developed a UV joint design which allows for better articulation angle while maintaining strength and reducing weight at the same time.
Dynamic Analysis of Multi Disc Rotating Stepped Shaft Through Signal Processing
Authors: Babu Rao K , Reddy D. Mallikarjuna
Published: May 2021

This study identifies a method for detection of irregularities like open cracks or grooves on a rotating stepped shaft with multiple discs, based on the Wavelet Transforms. Cracks are represented as reduction in diameter of shaft (groove) with small width. Single as well as multiple grooves are considered on stepped shaft at locations of stress concentration. Translational or rotational response curves/mode shapes are extracted from finite element analysis of rotor with and without grooves. Discrete and continuous 1D wavelet transforms applied on resultant response curve or mode shapes. The results show that rotational response curves or mode shapes are more sensitive to shaft cracks and key contributors to identify the location of cracks than translation response curves or mode shapes. Discrete Wavelet Transforms are accurate enough to locate the groove of smaller size. Effectiveness of detection by Wavelets Transforms is analyzed for Single as well as Multiple grooves with increase in grove depth. Increase in groove depth can be quantified by increase in wavelet coefficient and it can be an indicator.
Mechanical Properties of Graphene Reinforced Abaca Fiber Composites
Authors: Singh Shreyash , Khatri Harsh , Deshlahra Shobhit , Narendiranath Babu T.
Published: May 2021

The main aim of this research work is to study the mechanical properties of abaca natural fiber composite reinforced with graphene. Natural fiber composites seek a numerous application nowadays due to its high strength is to weight ratio, high impact resistance, thermal stability, and recyclability. The percentage compositions of graphene reinforcement in the matrix are varied. Alkali treatment of abaca fiber is done to enhance bonding at the fiber-matrix interface. Conventional hand layup method is used for fabrication of the composite material. Moulds were made according to ASTM standard to test its tensile properties. The result showed that incorporation of glass fiber increases the performance of abaca fiber composites. Natural fiber composites have many potential applications in the automotive, aerospace and construction industries.
Refreshable Braille Module Using Cam Actuated Mechanism
Authors: Aryan  , E Rajkumar , Doshi Shivam
Published: May 2021

Less than 3% of 145 million blind people in developing countries at present are literate [1]. At present, in most of the cases, speech output has been the medium for blind people to access materials. For content which require deep understanding such as technical texts etc., it is not an appropriate modality, moreover blind people are more accustomed to braille transcripts and adaptability issues to all audio resources is difficult. And thus, arises the need for a cheap, easily adaptable, less complex solution to the problem. Braille points are varied arrangements of raised dots representing characters which are identified by touch by visually impaired people. Here we discuss in detail, development of a dynamic/refresh-able Braille display which presents Braille points by the up-and-down movement of pins using a completely new, first of its kind, Cam actuated mechanism with just two actuation points instead of a standard 6 used by every single refresh-able braille board in the world at present. Two nested shafts having 8 arrays of precisely calculated and placed cam, each were responsible for keeping the pins in up and down state. The shafts were actuated using two micro-servo motors placed next to each other. X degree rotation of servo after transmission through gear and subsequently shaft resulted in a particular configuration. Henceforth calibration was done so that all braille alphabet could be produced with specific servo rotations.
TOPOLOGY OPTIMIZATION OF THE BELL CRANK & BRAKE PEDAL
Authors: Nandanwar Tanmay , Waghela Keyour , Gupta Eshaan , Narendiranath Babu T
Published: May 2021

Topology Optimization has been an effective tool for weight reduction and performance design and has essential applications in automobile industry. The main objective of this paper is to design a lighter weight bell crank and brake pedal than the existing design which is generally used in the automobile parts. The newly optimized design of bell crank and brake pedal is compared with the existing design. The CAD model of the bell crank and brake pedal is modeled using SOLIDWORKS software and the analysis of the newly optimized model is carried out using the Altair INSPIRE 9.5 . Using the above methodology, a light weight bell crank and brake pedal model is designed and the FEA analysis is used for obtaining the maximum and minimum value of displacement, % of yield, tension/compression, shear stress and von mises stress on the optimized design. The results of the design reflect that the weight of the bell crank has been reduced to 140 grams which is about 24% less weight then the existing design and the optimized weight of the brake pedal is reduced from 363g to 211g.
Analysis Of Low-Velocity Impact Response In Aa5083 Plate
Authors: Sairam V. , Kanna S.Kishor , Kumar P.S.Samuel Ratna
Published: May 2021

This paper investigates the low velocity impact performance of AA5083 using ABAQUS software. The impact resistance was measured in terms of depth of indentation created over AA5083. Low-velocity impact results indicates, that the angle of inclination of the impact resisting body have a great influence on the impact resistance properties. The analysis study was carried out for different orientations of the alloy plate with respect to the horizontal datum namely 30°,60°,90° respectively. A Finite Element Method (FEM) model has been developed using ABAQUS software tool to analyse and study the low-velocity impact test on the AA5083 plate. Results from the FEM model reveals that the depth of indentation over AA5083 is minimum when the angle is inclined at 90°.
Design of battery pack & controller for combined auto driven mini-harvester
Authors: Warghane Rahul S , Rajkumar E
Published: May 2021

The mechanized farming can promisingly increase the profitability and prevent the dependency of farmers on foreign labours. The design and implementation of Battery pack and controller for specially designed combined auto-driven mini harvester is presented in this paper. The mechanical load estimation and its mapping with electrical drives are formulated. The interfacing of electrical drives with remote operation is achieved by Electronic Arduino system. The relay control system is designed with individual drive system. The sketches are mapped with the functionality of drives. The drive selection is a dependant function of mechanical load requirement. The mechanical load estimation is done with actual mechanical failure consideration and design approach. The pin-out connections for all the ports are done on the basis of logical sketch command. The open source Arduino software is used to run the sketches. The sketch written for all the drives is compiled and demo prototype machine is tested for functioning. The run trail is successful and can conclude that the Arduino mega gives the sound interface with 8 channel relay. The computation and measurement results of power requirements for the controller and drive are within the limiting conditions.
Application of active vibration control on single stage spur gear
Authors: Menon Manas Raman , Hariprasad Tanay , Thomas Karun , Vemuluri Ramesh Babu , Darla Siva Prasad , Edwin Sudhagar P , Ashok B
Published: May 2021

Vibrations in a mechanical system can cause power losses or vibrational fatigue which leads to failure in the material. In the current scenario automotive vehicles majorly use passive vibrational control techniques for vibration attenuation. Passive vibrational control tend to be heavy in nature and can only control frequencies in the range of 100 – 200 Hz. Conversely, active vibrational control is the potential alternative to passive vibrational control, they consist of strain sensor, piezoelectric actuator, a control system and a power amplifier to draw the control actuator. The application of active vibrational control is flourishing due to the demand in critical vibrational control in extreme conditions (underwater, polar, space). This paper provides an overview of the applications of active vibration control on single stage spur gear. The vibrations emitted in a single stage spur gear is optimised by active vibration control.