bluuebunny/crossref_metadata_2025 huggingface dataset:
Mean maximal power from an on‐water 1000‐m time‐trial predicts lactate threshold power in well‐trained flat‐water sprint kayak athletes
Authors: Hogan Cruz , Binnie Martyn J. , Doyle Matthew , Peeling Peter
Published: January 2021

This study utilised on‐water graded exercise tests (GXT) to determine the power output (PO) corresponding to the first and second lactate thresholds (LT1PO and LT2PO), subsequently examining their relationship to the mean maximal power (MMP) and race time achieved across three on‐water sprint kayak time‐trials. Twelve well‐trained sprint kayak athletes completed an on‐water GXT and a 200‐, 500‐ and 1000‐m time‐trial utilising novel instrumented paddle technology. Stepwise multiple regression was used to determine whether equations incorporating 200‐, 500‐ and 1000‐m MMP data could be used as an alternative method for estimating LT1PO and LT2PO. On‐water GXT derived LT1PO and LT2PO were 151 ± 34 and 194 ± 39 W, respectively. For the 200‐, 500‐ and 1000‐m time‐trials, MMP were 528 ± 143, 358 ± 92 and 287 ± 67 W, respectively. Athletes’ LT1PO and LT2PO had very‐large inverse relationships to 200‐, 500‐ and 1000‐m time‐to‐completion (r = −.71 to −.85, P ≤ .010) and very‐large, to near‐perfect positive relationships to 200‐, 500‐ and 1000‐m MMP (r = .81 to. 94, P ≤ .001). The equation incorporating 1000‐m MMP alone provided the best prediction of LT1PO and LT2PO, explaining 78% and 88% of the variance, and yielding a standard error of estimate (SEE) of 11.3% and 7.1% for these measures, respectively. The results of this study provide further evidence to support the ecological validity of recently developed on‐water GXTs graded by PO, since LT1PO and LT2PO were significantly correlated to 200‐, 500‐ and 1000‐m performance. Practitioners could also predict LT2PO with reasonable accuracy based solely from a 1000‐m time‐trial; potentially providing an alternative, non‐invasive, competition‐specific protocol for threshold determination.

Highlights

The fact that LT1PO and LT2PO had very‐large, to near‐perfect positive relationships to 200‐, 500‐ and 1000‐m MMP suggests that coaches should consider these relative submaximal aerobic‐fitness variables when evaluating the performance of sprint kayak athletes, regardless of their race specialty.

While the SEE and 95% limits of agreement (95%LoA) values for the prediction of LT1PO may be too large to be practically meaningful, measures of LT2PO could be predicted with a reasonable level of accuracy based upon 1000‐m MMP.

The ability to inform athletes' LT2PO from a single 1000‐m time‐trial is advantageous since it would provide a more feasible, and time‐efficient testing protocol within the athletes' training schedule compared to GXTs, potentially allowing coaches and practitioners to monitor changes in LT2PO, and subsequently review individual training zones, more regularly.

Given that LT1PO and LT2PO derived from on‐water GXTs had very‐large, to nearly perfect relationships to 200‐, 500‐ and 1000‐m performance, practitioners may prefer to use on‐water, rather than laboratory‐based GXTs given their greater practical significance and ecological validity.
Place attachment: antecedents and consequences (Antecedentes y consecuencias del apego al lugar)
Authors: Hernández Bernardo
Published: January 2021

Place attachment refers to a process of person-environment interaction that has generated a substantial volume of research. This paper presents a summary of available knowledge regarding place attachment, focusing particularly on residential environments. It offers a definition of place attachment and presents some research strategies. Antecedent variables that contribute to the development of place attachment are also analysed, along with the consequences associated with place attachment. Finally, the relationship between place attachment and the experience of psychological well-being is analysed.
Operando characterisation of alumina-supported bimetallic Pd–Pt catalysts during methane oxidation in dry and wet conditions
Authors: Large Alexander , Seymour Jake , Quevedo Garzon Wilson , Roy Kanak , Venturini Federica , Grinter David C , Artiglia Luca , Brooke Emily , de Gutierrez Martha Briceno , Raj Agnes , Lovelock Kevin R J , Bennett Roger A , Eralp-Erden Tugce , Held Georg
Published: January 2021

Near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) was used to study the chemical states of a range of alumina-supported monometallic Pd and bimetallic Pd–Pt nanocatalysts, under methane oxidation conditions. It has been suggested before that for optimal complete methane oxidation, palladium needs to be in an oxidised state. These experiments, combining NAP-XPS with a broad range of characterisation techniques, demonstrate a clear link between Pt presence, Pd oxidation, and catalyst activity under stoichiometric reaction conditions. Under oxygen-rich conditions this behaviour is less clear, as all of the palladium tends to be oxidised, but there are still benefits to the addition of Pt in place of Pd for complete oxidation of methane.
Short-range magnetic behavior in manganites La0.93K0.07Mn1-

x
Cu
x
O3 (0.0 ⩽ x ⩽ 0.09) above the Curie temperature
Authors: Khammassi Fatma , López Jose F , Chérif Wajdi , Mendoza Aminta , Lanceros-Mendez Senentxu , Dammak Mohamed , Salazar Daniel
Published: January 2021

Manganites La0.93K0.07Mn1−x
Cu
x
O3

(
0.0
⩽
x
⩽
0.09
)
,

prepared by the solid state reaction method at high temperature, were studied structurally and magnetically. The unit cell parameters, as well as bond length

d

(

Mn,Cu)-O

 

Å

and the bond angle

θ

(

Mn,Cu)-

O

1

-Mn

, were determined from the Rietveld refinement of the x-ray diffraction patterns. The Fourier-transform infrared spectroscopy analysis shows that Cu2+ substitution induces variations in the vibration modes of the MnO6 octahedra. Magnetization vs. temperature

M

T

at low magnetic field

H=0
.01T

were performed in the range

5
<
T
<
300

K

under field coolingand zero field cooling conditions. All the samples exhibited a second-order paramagnetic–ferromagnetic (FM) transition at Curie temperature,

T

C

, in the range between 199 and 285 K. The inverse susceptibility,

χ

−
1

(
T
)

exhibits a linear Curie-Weiss (C-W) behavior for

T
>

T

CW

*

, while for

T

C

<
T
<

T

CW

*

, it shows a deviation from the linear behavior predicted by the Heisenberg model. The mentioned deviation of

χ

−
1

T

means that a short ferromagnetic state formation is present even for

T
>

T

C

, which were characterized by the experimental effective magnetic moment,

μ

eff

exp

.

A null spontaneous magnetization,

m

S

,

above

T

C

was evaluated for all samples by using the Kouvel-Fisher method. This work evaluates the short-range FM clusters by means of an extension of the C-W approach to the

T

C

<
T
<

T

CW

*

region, i.e.,

μ

eff

exp

(
T
)

=
2.3

C

(
T
)

μ
B

. Finally, the critical coefficient values,

β

and

γ

, showed that the 3D Heisenberg model fits adequately the

x=0
.0

and

x
=
0.03

samples, while the 3D Ising model fits the

x
=
0.09

sample.
Spin reorientation behaviour and dielectric properties of Fe-doped h-HoMnO3
Authors: Prakash Pulkit , Mishra S K , Prajapat C L , Das A
Published: January 2021

We have studied the magnetic structure, spin reorientation behaviour and dielectric properties of polycrystalline HoMn1−x
Fe
x
O3 (0.0 ⩽ x ⩽ 0.25) compounds using magnetization, neutron diffraction and dielectric measurements. These compounds crystallize predominantly in the hexagonal phase (P63
cm) with a small phase fraction of the orthorhombic phase (Pnma) which increases with increase in dopant concentration and a total suppression of the hexagonal phase is observed at x = 0.25. Doping Fe at the Mn site leads to an increase in the spin reorientation temperature (T
SR) from 33 K (x = 0) to 55 K (x = 0.1) while the T
N remains nearly constant at 72 K. The magnetic structure of the hexagonal phase was found to be Γ4 (P63′c′m) below T
N and Γ3 (P63′cm′) below T
SR. The magnetic ordering temperature of Ho3+ ions at 2(a) site appears to coincide with the T
SR only in the case of x = 0 sample. The Ho ions at 4(b) site are found to magnetically order below 8 K. The T
N of the Ho ions at both 4(b) and 2(a) sites do not appear to be affected by doping at the Mn site. The temperature variation of the Mn and Ho moments follow the Brillioun function dependence albeit with differing values of the molecular field constant λ
0 and λ
1. Short range magnetic order alone was found for the completely orthorhombic sample (x = 0.25). An anomalous suppression of the dielectric constant (ε) at T
N is observed in the case of hexagonal samples. Further, a linear correlation between Δε (= ε(T) − ε(0)) and the square of the antiferromagnetic moment M, is observed in these compounds.
Characterization of flexible and stretchable sensors using neural networks
Authors: Nguyen Xuan Anh , Chauhan Sunita
Published: January 2021

Flexible and stretchable sensors made of highly deformable materials have been an active research area with many promising applications. These sensors have the advantages of being highly compliant and elastic, which improves the poor ventilation of the traditional rigid sensors. However, the major drawbacks of flexible and stretchable sensors are the non-linearity and hysteresis in their response, as well as other performance criteria such as precision and repeatability, which may further deteriorate with usage and therefore require pre-emptive calibration from time to time. Most of the existing works often concentrate on new designs and materials and often undermine these issues. To achieve greater precision sensing, this paper proposes an approach with four feature extractors, namely, long short-term memory, gated recurrent units, temporal convolutional networks (TCNs), and a fully convolutional network, to characterize the properties of such sensors. The proposed approach can serve as a calibration method as well as an end-to-end measurement method depending on the settings of the input and the output. We adopted various public datasets to validate the performance of the proposed approach. The experimental results show that the model with a TCN as the feature extractor can give highly promising results with a median error of 0.66% on a kirigami-like sensor and less than 3% on microfluidic-based pressure sensors. With a high performance on representative datasets, the proposed approach is believed to be extendable to other stretchable sensors and actuators for performance analyses, which could greatly increase the adaptation of such sensors in many engineering applications.
SNEWS 2.0: a next-generation supernova early warning system for multi-messenger astronomy
Authors: Al Kharusi S , BenZvi S Y , Bobowski J S , Bonivento W , Brdar V , Brunner T , Caden E , Clark M , Coleiro A , Colomer-Molla M , Crespo-Anadón J I , Depoian A , Dornic D , Fischer V , Franco D , Fulgione W , Gallo Rosso A , Geske M , Griswold S , Gromov M , Haggard D , Habig A , Halim O , Higuera A , Hill R , Horiuchi S , Ishidoshiro K , Kato C , Katsavounidis E , Khaitan D , Kneller J P , Kopec A , Kulikovskiy V , Lai M , Lamoureux M , Lang R F , Li H L , Lincetto M , Lunardini C , Migenda J , Milisavljevic D , McCarthy M E , O Connor E , O Sullivan E , Pagliaroli G , Patel D , Peres R , Pointon B W , Qin J , Raj N , Renshaw A , Roeth A , Rumleskie J , Scholberg K , Sheshukov A , Sonley T , Strait M , Takhistov V , Tamborra I , Tseng J , Tunnell C D , Vasel J , Vigorito C F , Viren B , Virtue C J , Wang J S , Wen L J , Winslow L , Wolfs F L H , Xu X J , Xu Y
Published: January 2021

The next core-collapse supernova in the Milky Way or its satellites will represent a once-in-a-generation opportunity to obtain detailed information about the explosion of a star and provide significant scientific insight for a variety of fields because of the extreme conditions found within. Supernovae in our galaxy are not only rare on a human timescale but also happen at unscheduled times, so it is crucial to be ready and use all available instruments to capture all possible information from the event. The first indication of a potential stellar explosion will be the arrival of a bright burst of neutrinos. Its observation by multiple detectors worldwide can provide an early warning for the subsequent electromagnetic fireworks, as well as signal to other detectors with significant backgrounds so they can store their recent data. The supernova early warning system (SNEWS) has been operating as a simple coincidence between neutrino experiments in automated mode since 2005. In the current era of multi-messenger astronomy there are new opportunities for SNEWS to optimize sensitivity to science from the next galactic supernova beyond the simple early alert. This document is the product of a workshop in June 2019 towards design of SNEWS 2.0, an upgraded SNEWS with enhanced capabilities exploiting the unique advantages of prompt neutrino detection to maximize the science gained from such a valuable event.
Ultrathin Co films with Pt and Au covers—magnetic and structural properties driven by Ga+ ion irradiation
Authors: Mazalski P , Ohnoutek L , Sveklo I , Beran L , Kurant Z , Powroźnik W , Wawro A , Liedke M O , Butterling M , Wagner A , Fassbender J , Hamrle J , Antoš R , Kletecka V , Veis M , Maziewski A
Published: January 2021

The X/Co 3 nm/Y (where X, Y = Au, Pt) trilayers with as deposited in-plane magnetization alignment were irradiated with 30 keV Ga+ ions in the wide range of ion fluence. The samples were investigated by means of complementary techniques: magneto-optical magnetometry and spectroscopy (in the photon energy range from 1.2 eV to 4.5 eV), magnetic force microscopy, positron annihilation spectroscopy, x-ray diffraction and reflectivity. Difference in miscibility of interface atoms is clearly manifested in various intermixing extent at Co/Pt and Co/Au interfaces and consequently in magnetic properties of the irradiated trilayers. Low irradiation fluence (∼1014 ions cm−2) leads to ∼1 nm interfaces broadening without visible surface etching for all samples, which is related with a distinct drop of magnetic anisotropy. However, the high irradiation fluence (∼5 × 1015 ions cm−2) results in enhanced interface broadening and significant surface etching (∼5 nm) partially removing also Co atoms. Tensile strains (up to 0.5%) were developed in the cover layers. The tensile strain, layers intermixing and the creation of Co–Pt(Au) alloys with different composition formed by irradiation are correlated with the increase of magnetic anisotropy. Moreover it was observed that substitution of Au instead of Pt (as a cap or buffer layer) results in substantial increase of perpendicular magnetic anisotropy. Maximal increase of magnetooptical parameters was observed for Pt/Co/Pt layer. Irradiation induced changes of concentration profiles are revealed using magnetooptical spectra, x-ray reflectivity spectra and simulations with use of binary collision approximation.
First evidence of dominant influence of E
×
B drifts on plasma cooling in an advanced slot divertor for tokamak power exhaust
Authors: Ma X. , Wang H.Q. , Guo H.Y. , Stangeby P.C. , Meier E.T. , Shafer M.W. , Thomas D.M.
Published: January 2021

Addressing power exhaust in tokamaks is presently recognized as one of the major remaining open issues for the development of fusion reactors. At the forefront of this endeavor is the effort to develop an advanced divertor by maximizing dissipation of plasma power and momentum inside the divertor. Here, we demonstrate, for the first time, that the electromagnetic (
E
×
B
) drifts exert a key influence on plasma and gas dynamics in a new advanced slot divertor in the DIII-D tokamak, named the small angle slot (SAS). SAS leverages the effect of drifts to achieve a highly dissipative divertor with electron temperature T
e ≲ 10 eV over a wide range of plasma densities, for ion
B
× ∇
B away from the divertor, as used for advanced tokamak operation on DIII-D. Modeling with the SOLPS-ITER code shows that for this drift direction, the
E
×
B
flow carries particles toward the outer common flux region (CFR) via the private flux region (PFR), reinforcing neutral recycling and enhancing divertor dissipation. In contrast, for the opposite field direction, the
E
×
B
flow carries particles away from the outer CFR into the PFR, offsetting the anticipated SAS geometric effects. This finding is an important step in the understanding of the behavior of advanced divertors for achieving a power exhaust solution for fusion reactors.
Influence of the degree of off-design of the traction nozzle of a jet reaction turbine on its efficiency
Authors: Vaneev S , Rodymchenko T , Meleychuk S , Baga V , Bolotnikova O
Published: January 2021

At the present stage of social development, the need for rational use of energy resources of the planet is particularly acute. Most countries have already faced the problem of the energy crisis. An appropriate way to solve this problem is the utilization of secondary energy resources. With the help of turbine generators, it is possible to reduce the pressure and utilize the potential energy of excess pressure of gas or vapours to produce electricity. Such units can be created based on a jet reaction turbine. The study aims to assess the impact of the degree of off-design of the traction nozzle on the efficiency of the jet reactive turbine. The analysis of the factors influencing the efficiency of the jet reaction turbine is carried out in the work. The obtained efficiency rate for the jet reactive turbine depending on the given dimensionless velocity of λout t at the inlet pressure of the inlet nozzle of 2, 4, 6 and 10 MPa in the design mode (at the degree of off-design of S = 1) and in the off-design modes of operation ( S> 1). Graphical dependencies of the jet reaction turbine efficiency rate on the given circular velocity of the impeller are constructed (U− = 0… 0.7). The research shows that with increasing pressure at the inlet to the inlet nozzle, the efficiency rate of the turbine increases, and the optimum of the efficiency rate is shifted towards the increase of the given circular velocity of the impeller, both in the design and off-design operating modes. It is found that the greatest value of the efficiency rate is acquired at the design mode of operation of the traction nozzle, i.e. at S = 1.
Influence of different volute casings theoretical methods design on pump working processes
Authors: Chernobrova A , Sotnyk M , Moloshnyi O , Antonenko S , Boiko V
Published: January 2021

The work is devoted to determining the influence of methods and recommendations for the design of a volute casing on the flow structure and the efficiency of the double-entry centrifugal pump. Volute casing designed by the constant-velocity method of the fluid according to the recommendations of A. Stepanoff, volute casing designed by the method of conservation of angular momentum of the flow, and the recommendations of C. Pfleiderer and A. Lomakin were designed and researched. The proposed designs were compared with the base volute casing. The analysis was performed based on the results of numerical simulation of the working process of the pump in the software ANSYS CFX at different flow rates. One impeller geometry and a constant volute casing outlet diameter were used to minimize the influence of other pump design factors on the working process of the volute casing. The distribution of pressure and velocity in the volute casing is analysed. Analysis of velocities and angular momentum along the volute casing showed the same deviation of them values. In general, the characteristics of the flow inside the volute casing conform indicated method. The article provides recommendations for choosing a method of designing a pump volute casing.
The analysis of the performance of a sewage pump in terms of the wear of hydraulic components
Authors: Moloshnyi O , Szulc P , Moliński G , Sapozhnikov S , Antonenko S
Published: January 2021

The paper presents the comparison of the performance of the three-blade centrifugal pump operating in sewage water in the function of time. Two conditions of the analysed pump were investigated: a new one and one after a long period of utilization. The main objects of research were the impeller, due to its enormous wear, and the L–shape wear ring. Three dimensional optical scanning was applied to reflect the real geometrical parameters of the analysed pump. The investigations were conducted by means of numerical simulations and a real test. The achieved results indicate the impact of the wear on the performance curves of middle specific speed sewage pump.
Improving the efficiency of the operating process of high specific speed torque-flow pumps by upgrading the flowing part design
Authors: Kondus V Y , Puzik R V , German V F , Panchenko V O , Yakhnenko S M
Published: January 2021

The article is devoted to the research of the torque-flow pump operating process. Its work is closely connected to the formation and stable functioning of the toroidal vortex. The theoretical bases of the formation of a toroidal vortex and the process of energy transfer in a torque-flow pump are considered in the research (vane and vortex components of the operating process). The fact of the presence of some additional hydraulic losses due to the mismatch of the location of the toroidal vortex center and the impeller blade edges has been established. The urgency of the paper is increasing the efficiency of torque-flow pump by improving its flowing part. The upgrade of the pump consists of the theoretical justification and practical implementation of the reduction of these additional hydraulic losses. In this aspect, the location of the impeller blade edge is aligned with the toroidal vortex center. The research was performed by conducting a numerical investigation. The calculations of a high specific speed torque-flow pump of three different design configurations of the impeller blades were performed. Practically confirmed increasing of the head (by 3.2 m) and efficiency (by 7-8%) of the pump with the second design of the impeller blades.
Characteristics improvement of labyrinth screw pump using design modification in screw
Authors: Andrenko P , Rogovyi A , Hrechka I , Khovanskyi S , Svynarenko M
Published: January 2021

The labyrinth screw pumps are widespread in the chemical and oil industries. The scope of the possible use of the labyrinth-screw pumps working in aggressive mediums is much wider in comparison with the pumps with similar pressure and flow parameters. This is due to the type of operation and lack of the mechanical friction of the parts. Increasing the pump flow rate can be achieved by reducing hydraulic friction resistance or profiling the inlet and outlet of the fluid flow. The flow channel of the labyrinth screw pump has been improved and a new design of its movable operating elements has been developed based on the proposed concept of jet resistor diodes. The reduction of hydraulic resistance in the flow channel of the pump with the working fluid flow in the forward direction and increasing the resistance of the diode made it possible to obtain a more efficient design. The results of improvement are compared with experimental data. The simulation of the flow in the pump is performed by solving the RANS equations with the SST turbulence model. The flow predictions in the flow section are obtained. The flow rate characteristics of typical and developed pumps are calculated. The developed pump design allows for increasing its flow rate by almost 10%. At the same time as the flow rate of the pump increases its power output. The efficiency of the industry-developed labyrinth screw pump application is proven by comparing the flow rate characteristics of the pumps.
Modifications of propeller pumps design algorithm. Numerical and laboratory tests
Authors: Altyntsev I , Homa D , Peczkis G
Published: January 2021

This article presents the new construction of a centrifugal impeller pump which supplies the cooling system in coal power plants. The article also shows the history of producing this kind if pumps for unified power units of 125 MW and 200 MW which dominate in Poland. The process of numerical analysis and conventional calculations leading to the improvement of qualities of the flowing system exceeding literature indicators are presented. The article shows the problems which appeared during assembling the pump in its target workplace. The results of the measurements of the pump flowing system in its target workplace are presented.
Developing a system and criteria for directed choice of technology to provide required quality of surfaces of flexible coupling parts for rotor machines
Authors: Melnyk V , Vlasovets V , Konoplianchenko Ie , Tarelnyk V , Dumanchuk M , Martsynkovskyy Vas , Semirnenko Yu , Semirnenko S
Published: January 2021

The paper discusses the process of normal friction and wear as a result of fretting corrosion, as well as measures to reduce its level. There are considered the issues of reliability and accuracy of the connection of “shaft - sleeve with key” type, which is of particular danger. The disadvantages of the considered connections are shown, namely the relative complexity of the disassembly-assembly processes; high level of stress concentration; the tendency to corrosion at contact. There has been proposed a physically based mathematical model of the wear process for the strengthened surfaces of the flexible coupling parts on the friction conditions. By using the friction work value, the model allows determining the wear expressed through the change in the surface roughness. A method has been developed for determining the constant of the wear equation for various materials of friction pairs. Using the energy and economic criteria, the technique of the integral description of the method for achieving the required quality of the surface layers of the elastic coupling parts is given. A mathematical model has been developed to reliably allow predicting the wear amount for the surfaces of the elastic coupling parts whose surface layers are formed in various ways. It is proposed a system for the directed choice of the technologies to produce the surface layers of the flexible coupling parts taking into account all the stages of their life cycles. In doing so, both economic and environmental requirements are also taken into consideration. The use of the system for the direct choice of the technology to ensure the required quality of the flexible coupling parts at the repair stage allows more economically solving the problem of restoring their performance. As practice shows, at this stage, the application of the results of the scientific research gives a significant economic effect.
Influence of operational changes of clearances in pump channels on the work of the automatic balancing device
Authors: Tarasevych Y , Sovenko N , Savchenko I
Published: January 2021

Automatic balancing devices are used to balance the axial force in many multistage centrifugal pump designs. Despite the obvious advantages of these devices their failure is one of the main reasons for the complete failure of the pump unit. The axial force acting on the pump rotor can be changed under pump operation in a sufficiently large range and up to several tens of tons. Usually the calculation of automatic balancing device is made under pump's operating parameters. At the same time it is possible the changing of value of the axial force generated by the automatic balancing device on the calculated parameters due to the interdependence of hydrodynamic processes in clearances of the flow part of the pump and in the clearances of the balancing device. The analysis of possible causes of the axial force value changes as a result of unbalanced pressure forces acting on pump impellers and counterbalancing of axial forces arising in face gap balancing device is presented. An improved methodology for calculating the estimation of the axial force arising in the balancing device using the example of industrial multistage centrifugal pump is proposed.
Prediction of stability against subsonic flutter for axial turbine machine compressor blade assemblies
Authors: Zinkovskii A P , Stel’makh A L
Published: January 2021

The developed method for prediction of their dynamic stability limit is described for the first flexural and torsional modes of vibrations against subsonic flutter. It involves the use of the database of the critical reduced frequencies of the blade vibrations as a dynamic stability limit within the wide range of variations of the following characteristics: phase angle of flexural, torsional and flexural-torsional vibrations of the adjacent blades; attack angle; reduced vibration frequency; geometric parameters for the airfoil and cascade; law of motion for blade airfoils. The algorithm realized as the numerical software assumes the determination of the critical reduced frequencies in the most loaded section of the full-scale blade assembly via the analysis of the distribution of the relative flow rate, attack angle, amplitudes of vibrations over the blade height and the subsequent comparison with the functional defining its critical value for different attack angles. The results of practical implementation of the developed procedure are given for the assessment of the stability of the blade assemblies of axial compressors in some modern aircraft gas-turbine engine at the first flexural mode of vibrations. It is implied that the proposed method allows one to select the optimal reduced frequency of vibrations of the blade assembly for the specified geometry of its peripheral sections and attack angle of the mainstream flow upon the condition of subsonic flutter at the engine design state.
Determination of material parameters of rubber and composites for computational modeling based on experiment data
Authors: Krmela J , Artyukhov A , Krmelová V , Pozovnyi O
Published: January 2021

The article deals with determination of material parameters of elastomer (rubber) for computational modeling based on experiment data - hardness and also determination of materials parameters of specific composite materials for next-generation tires. Mooney-Rivlin parameters of elastomers can be determined on the basis of the Shore A hardness. There are exist equations which can be used conversion of the mentioned hardness to material parameters of elastomers. The procedure is such that the Shore A hardness is converted to the elastic or shear modulus and then Mooney-Rivlin material parameters are determined from the modulus. But these equations can lead to different results for the same hardness. In this paper, these results are comparison. The results can be used as input material data of rubber seals of pump and compressor machinery for their computational modeling. Methods of determination of the modulus of elasticity of composite with elastomer matrix are necessary created based on experimental data of static tensile test of specimens of a radial tire casing. Next results can be applied for simulations of tires with interaction roads which used for modern passenger cars and trucks and the results can be applied for simulation of conveyor belts where elastomer is used.
Increasing fretting resistance of flexible element pack for rotary machine flexible coupling Part 1. Analysis of the reasons affecting fretting resistance of flexible elements for expansion couplings
Authors: Tarelnyk V , Hlushkova D , Martsynkovskyy V , Dumanchuk M , Antoszewski B , Kundera Cz , Konoplianchenko Ie , Tarelnyk N , Hudkov S , Zahorulko A
Published: January 2021

It has been made an analysis of the rotor machine flexible coupling (FC) failure reasons. As a result, it has been found out that the flexible coupling trouble-free operation period is limited by the pack of the flexible elements (FE) durability which depends on the fretting resistance of the individual flexible elements (plates) of the pack. The investigations with the use of an electron microscope have proved that there are at least three stages of the FE destruction: the formation of microfractures in the form of caverns at separate points of the FE destruction zone, which microfractures preserve microparticles of the destroyed metal in a confined space; weakening of the compression force affecting the plates and the wear product release from the fracture site; occurrence of abrasive wear resulting in the complete destruction of the FE. There has been substantiated the need in performing the FE stress-strain state analysis and determining the geometric and strain parameters of the strain zone, which can serve as a reserve for increasing the FE fretting resistance.
The scenario-based variations and causes of future surface soil moisture across China in the twenty-first century
Authors: Fan Keke , Zhang Qiang , Li Jianping , Chen Deliang , Xu Chong-Yu
Published: January 2021

Surface soil moisture (SSM) is a key factor for water and heat exchanges between land surface and the atmosphere. It is also important to water resources, agriculture, and ecosystems. In the backdrop of global warming, SSM variations and potential causes are not well-known at regional scales. Based on soil moisture (SM) data from GLDAS-Noah and 16 global climate models (GCMs) selected from 25 GCMs in CMIP5, we analyzed spatial distribution and temporal changes of SSM in China and quantified fractional contributions of four meteorological factors to the SSM variations. The selected models have the same direction of historic trends in SSM during 1981–2005 as those in the GLDAS SSM data which were also further used to calibrate the trends simulated by the 16 GCMs. Based on the calibration results for the 16 GCMs, future SSMs for nine regions were analyzed in mainland China under four Intergovernmental Panel on Climate Change emission scenarios. No significant changes were identified in SSM across most regions of mainland China under RCP2.6 scenario. However, there is a general wetting tendency in the arid regions and drying tendency across the humid regions under all the scenarios except RCP2.6. In general, the higher the global temperature raises, the more grids with significant increase or significant decrease in SSM. These findings contradicted prevailing view that wet regions get wetter and dry regions get drier. Attribution analysis indicates that precipitation acts as the major driver for SSM variations and contributes up to 43.4% of SSM variations across China. These results provide new insights into future SSM response to climate warming and a scientific basis to mitigation and adaptation works related to SSM in the future.
The use of computer visualization in the analysis of breathing curves
Authors: Berestneva O , Lyzin I , Yumasheva A , Marukhina O , Trufanov A
Published: January 2021

Researchers in diverse domains use advanced computer techniques to describe complex entities and processes and impressively visualize those which are often unavailable for direct observation. However, one should emphasize that computer visualization conception implies more than just a convenient, impressive, or high rate information transfer. It also considers a problem of perception, processing, and further cultivation of such important personal qualities as intuition, professional “talent”, and figurative thinking which are of value for experts in any domain. Computer visualization comprises traditionally such sophisticated techniques as computer graphics, animation and virtual reality. Traditionally, computer graphics has delivered strong instruments for creating, processing, and interacting with data representations. Interactive paradigm has led to emergence of a new scope within the problem of artificial intelligence, which is called cognitive computer graphics. The use of cognitive graphics allows physicians, analyzing modest volume of information, to draw significant conclusions. In whole, cognitive graphics forms a separate subfield in medical research. Visualization provides experts with data in current state of patients just to monitor their conditions continuously. In this article, we show the use of computer visualization to study characteristics (including network imprints) of such a common disease as bronchial asthma. The patients were grouped according to influence degree of psychological factors to the occurrence, progression and course stages of the disease. The study focuses on comparison and analysis of the patient’ spirograms and demonstrate presence of physiological and psycho-physiological features among patients with diagnoses of bronchial asthma. In this respect computer visualization provides a solid platform for thorough research and deep analysis in spirometry.
Investigation of edge detection methods using the example of wave field pattern image
Authors: Yakimenko A A , Makfuzova A I
Published: January 2021

This article explores the methods of detecting boundaries in images of wave field patterns. As a result, an application for image processing was developed using Sobel, Prewitt, Roberts, Gabor and Canny filters and experiments were carried out to detect the edge on images of wave field patterns. In conclusion, the quantitative and qualitative characteristics of the filters were presented, and a conclusion was made on the selection of the boundary detection filter. The results of this study will be used in the study of the neural network neocognitron for the recognition of geological and physical models of environments (GPME). This work was supported by the RFBR grant No. 19-07-00170.
Functioning of back-to-back high voltage direct current link model in Tomsk electric power system
Authors: Maltsev A P , Rudnik V E , Malkova Y Yu , Ufa R A
Published: January 2021

In this article the research results of steady-state and dynamic performance of asynchronous back-to-back HVDC link in Tomsk electric power system are presented. It is proposed to use the back-to-back HVDC link to provide an asynchronous link for parallel operation of the North and South parts of Tomsk electric power system. The steady-state stability limit and maximum allowed power flow were defined. Based on this the more effective location and power of back-to-back HVDC link were determined. Therefore, it is shown the application of back-to-back HVDC link decreases the level of short-circuit current, power fluctuations and increases the stability of load operation, especially of motor load at substation.
Preparation and properties of composite material based on hafnium diboride and aluminum
Authors: Belyakovich S A , Mostovshchikov A V , Ilyin A P , Gubarev F A
Published: January 2021

Hafnium diboride (HfB2) in aluminum matrix (Al) material was prepared by diffusion sintering of a mixture of hafnium diboride and aluminum micropowders. The effect of the hafnium diboride content (HfB2) in the aluminum matrix (Al) on sintering characteristics and properties of the samples is presented. The effect of microwave activation of the aluminum powders has been established. The diffusion sintering behavior was concluded. The material properties and structure were defined.
Development of impulse method for transformer winding condition control technology
Authors: Mytnikov A , Lavrinovich A , Strugov V , Saqib M
Published: January 2021

Mechanical shift of windings is serious problem of power transformers which belong to the very significant components of power engineering system. Mechanical displacements and following insulation failure due to short circuit and inrush currents can lead to an emergency situation. That’s why the effective control technology of windings is an relevant task of a current power engineering. A new approach to winding state control technology is described in the paper. The described technology is based on nanosecond probing impulse duration with short (no more than 20 ns) rapidness of front impulse. The experimental results of sensitivity growth at decreasing front pulse duration are shown. The experimental equipment and research are described. It is established that duration of probing impulse has optimum value around 100ns. It is shown that it is possible to do a condition control under operating voltage. It is shown that both shorter probing impulse and front of probe pulse duration allows upgrading common effectiveness of the diagnostic technology.
Megawatt PV-diesel power stations in the Arctic
Authors: Dmitrienko V N , Lukutin B V , Popov M M
Published: January 2021

The work of hybrid energy complexes of significant installed capacity based on photovoltaic and diesel generation in the northern regions of Yakutia is considered. The considerable remoteness of settlements from the country’s central energy system, the cargo delivery inaccessibility, as well as extreme climatic conditions determines the use of a hybrid energy complex with continuous diesel generation (without energy storage use).
Automated filtering and polygonal reconstruction of virtual skull model based on computed tomography
Authors: Grif M G , Grif A M
Published: January 2021

A method of automated filtering and polygonal reconstruction of the skull virtual model using the methods of “Marching cubes” and “Connected component labeling” is considered. An algorithm for effective software implementation is described. A computational experiment on computed tomography data consisting of 244 DICOM images is presented. The experimental results confirm the correctness and computational efficiency of the algorithm.
The calculation of the campaign of reactor RITM-200
Authors: Savitsky D E , Kuzmin A V
Published: January 2021

In this paper, the campaign of RITM-200 reactor was calculated. The duration of the campaign was determined taking the net capacity factor into consideration. The calculated duration concurred with the known data. The neutron parameters were calculated using the effective temperature method. The presence of burnable absorber rods was taken into account. Their effect was considered using the diffusional approach. The iterative computations were used to finally determine the temperature of the neutron gas. At the end, the reactivity curve displaying different effects inside fuel, namely fuel and gadolinium burn-out, the poisoning and slagging was drawn.
Whole blood clotting time assessment by method of laser-speckle correlation
Authors: Liushnevskaya I D , Li L , Gubarev F A , Nosarev A V , Gusakova V S
Published: January 2021

The paper presents the results of study of the coagulation process of the whole blood with anticoagulant using the method of laser speckle correlation. The clotting time dependence curves of the correlation coefficient have been presented and discussed. Analyzing the changing trend of these curves is possible to assess the clotting time, which prove the capability of using the method of laser speckle correlation for determining the diseases of blood coagulation.
Analysis of barriers to the development of Industrial Internet of Things technology and ways to overcome them
Authors: Zhmud V , Liapidevskiy A , Avrmachuk V , Sayapin V , Stukach O , Roth H
Published: January 2021

As is known, in 2019 the national program “Digital Economy of the Russian Federation” was launched. In the first phase, nine roadmaps were developed, of which six were approved by the Prime Minister. Participation in the development of these roadmaps provides a fresh perspective on some particular problems. The authors reveal some details of the approach to the implementation of the “Industrial Internet of Things” direction. Some specific differences of the industrial Internet from the regular Internet are discussed using examples. Some conclusions are drawn about the directions for further research in this area.
Method for numerical optimization of the parameters of regulator from unstable condition
Authors: Voevoda A A , Romannikov D O
Published: January 2021

The task of selecting the values of coefficients for a given controller structure from the initial unstable position is considered using the methods of numerical optimization. A method is proposed which consists in correcting the error function which is used for optimization. The main idea is multiplication by the exponent in the degree of the simulation step which the convergence of the transition process is achieved. After reaching convergence, you can perform numerical optimization. It is recommended to reduce the value of the exponent so that the figure of the transition process remains convergent. Further, when a stable transition process is reached, the value of the exponent should be zeroed out and then the optimization procedure for the error of the transition process should be performed without adjusting it until the change in the value of the objective function changes less than the specified threshold value. An example of such optimization is considered on the example of the transfer function of a second order oscillator.
High-level architecture for a digital oilfield: features of the transition to data-driven decision management
Authors: Savelev A O
Published: January 2021

This paper is devoted to the design of a distributed heterogeneous data warehouse of a digital oilfield. With increasing amounts of data collected from intelligent controllers and sensors, the lack of mechanisms for combining data from different sources and providing them to consumers affect the overall management efficiency. In addition, without it is impossible making the next logical step – the effective application of intelligent analysis methods. The paper describes the high-level architecture, as well as subsystems of operational management and decision support. The presented data are intermediate results of the project “Digital oilfield heterogeneous distributed data warehouse for informational support of decision-making processes”.
Dielectric particle-based strategy to design a new self-bending subwavelength structured light beams
Authors: Minin I V , Minin O V
Published: January 2021

During last 2 years it was shown that an electromagnetic field can be made to curve after propagation through a simple dielectric material of special shape, which adds a new-found degree of simplicity. This effect was termed ‘photonic hooks’ – it is an unique electromagnetic beam configuration behind a mesoscale dielectric particle with a broken symmetry and differ from Airy-family beams. PH features the radius of curvature, which is about 2 times smaller than the electromagnetic wavelength – this is the smallest curvature radius of electromagnetic waves ever reported. The nature of a photonic hook is in dispersion of the phase velocity of the waves inside of particle, resulting in interference. Here, we report a new dielectric particle-based strategy to design self-bending subwavelength structured light beams.
The possibility of obtaining materials by plasma dynamic synthesis in the Ti-O system
Authors: Sivkov A A , Vympina Yu N , Rakhmatullin I A , Ivashutenko A S , Shanenkova Yu L
Published: January 2021

The possibility of obtaining a dispersed material by the method of plasma dynamic synthesis in the Ti-O system is shown. The plasma dynamic synthesis is based on the operation of a pulsed high-current coaxial magnetoplasma accelerator with titanium electrodes. The obtained product was investigated by X-ray diffraction method and transmission electron microscopy. The results showed the presence of two main titanium oxide (IV) crystalline modifications: anatase with tetragonal syngony and rutile also with tetragonal syngony. Moreover, the dominant modification is anatase in synthesized material.