bluuebunny/crossref_metadata_2025 huggingface dataset:
Can Small-side Games Provide Adequate High-speed Training in Professional Soccer?
Authors: Asian-Clemente Jose , Rabano-Muñoz Alberto , Muñoz Borja , Franco Jesus , Suarez-Arrones Luis
Published: November 2020

The aim was to compare the running activity in official matches with that achieved in two small-sided games, designed with the same relative area per player but with different constraints and field dimensions, aiming to stimulate high-speed and very-high-speed running. Seventeen young professional players played one 5 vs. 5+5 with 2 floaters, varying in terms of whether there was a change of playing area (SSGCA) or not change (SSGNC). Running activity was monitored using GPS and the following variables were recorded: total distance covered; high-speed distance (18–21 km·h−1); very high-speed distance (>21 km·h−1); peak speed; accelerations and decelerations between 2–3 m·s−2 and above 3 m·s−2. SSGCA achieved statistically higher total distance, high-speed, peak speed and number of accelerations and decelerations than SSGNC (large to small magnitude). Both drills showed statistically greater high speed, number of accelerations and decelerations than official matches (large to small magnitude). Moreover, SSGCA exhibited statistically more total distance and distance at higher speed than official matches (moderate and small magnitude, respectively). In contrast, official matches showed statistically higher peak speeds than both training tasks and more very high speed than SSGNC (large and moderate magnitude, respectively). Coaches could use SSGCA to promote greater running activity in soccer players.
Surgical Treatments of Epilepsy
Authors: Ahmad Shahjehan , Khanna Ryan , Sani Sepehr
Published: November 2020

Nearly 30% of epilepsy patients are refractory to medical therapy. Surgical management of epilepsy is an increasingly viable option for these patients. Although surgery has historically been used as a palliative option, improvements in technology and outcomes show its potential in certain subsets of patients. This article reviews the two main categories of surgical epilepsy treatment—resective surgery and neuromodulation. Resective surgery includes temporal lobe resections, extratemporal resections, laser interstitial thermal therapy, and disconnection procedures. We discuss the three main types of neuromodulation—vagal nerve stimulation, responsive neurostimulation, and deep brain stimulation for epilepsy. The history and indications are explored for each type of treatment. Given the myriad types of resection and neuromodulation techniques, patient selection is reviewed in detail, with a discussion on which patients are most likely to benefit from different treatment strategies. We also discuss outcomes with examples of the pertinent landmark trials and their results. Finally, complications and surgical technique are reviewed. As new indications emerge and patient selection is refined, surgical management will continue to evolve as an adjuvant therapy for epileptic patients.
Incidence of Scaphoid Fractures and Associated Injuries at US Trauma Centers
Authors: Wells Matthew E. , Nicholson Tyler C. , Macias Reuben A. , Nesti Leon J. , Dunn John C.
Published: November 2020

Backgound The scaphoid is the most commonly fractured carpal bone and often presents as a diagnostic challenge. Fractures can often go unnoticed on initial radiographic evaluation and clinical presentation can vary significantly among patients. Awareness of high-risk cohorts assists practitioners in making the appropriate clinical diagnosis of acute scaphoid fracture.

Materials and Methods The National Trauma Data Bank is the world's largest trauma data repository. Utilizing the 2016 public use file, we isolated scaphoid fractures by anatomic fracture location by utilizing International Classification of Diseases, 10th revision coding. Reported cases of distal pole (S62.01), waist (S62.02), and proximal pole (S62.03) were included. This data was then queried to determine trends in mechanism of injury, demographic information, and associated injuries.

Results There were a total of 968,665 patients with 2,769 cases of reported scaphoid fractures resulting in 286 scaphoid fractures per 100,000 person-years. Males were more likely to sustain a scaphoid fracture than females. The most commonly encountered associated injuries were distal radius fractures, distal ulnar fractures, and nonscaphoid carpal bone fractures, respectively.

Conclusions Scaphoid fractures presenting to trauma centers are more commonly reported among males and those involved in motor vehicle accidents or falls. Appropriate scaphoid-specific radiographic imaging should be obtained as well as wrist and elbow images to evaluate for concomitant injuries, especially distal radius fractures.
Validation of the Macroscopic Anterior Cruciate Ligament Status Using the Oxford Classification System in Relation to Cartilage Defects on the Medial Tibial Plateau in Osteoarthritic Knees
Authors: Hiranaka Takafumi , Hida Yuichi , Tanaka Toshikazu , Okimura Kenjiro , Fujishiro Takaaki , Okamoto Koji
Published: November 2020

This study evaluated the relationships between anterior cruciate ligament (ACL) grading using the Oxford classification system and cartilage defects on the medial tibial plateau to clarify the validity of the system. We studied the location and size of a full-thickness cartilage defect of the medial tibial plateau in 154 knees (97 patients) treated by unicompartmental (113) or total (41) knee arthroplasty between April 2017 and January 2018, and analyzed their relationship to the anterior cruciate ligament (ACL) grade, Grade 1 (normal), Grade 2 (synovial damage), Grade 3 (longitudinal split), Grade 4 (friable and fragmented), and Grade 5 (absent). Significant trends in decreased posterior preserved cartilage, increased defect length, and posteriorized defect center were associated with increasing ACL grade. Multiple comparison analysis revealed that the measurements were significantly different between ACL functional (Grades 1–3) and ACL deficient (Grades 4 and 5). On the other hand, the anterior preserved cartilage was consistent among the Grades. The macroscopic Oxford ACL classification system well described the disease progression where the cartilage defect extends posteriorly with ACL damage. However, 38% of ACL deficient knees had well-preserved posterior cartilage with no evident tibial anterior translation.
Principal factors in performance of indirect-drive laser fusion experiments
Authors: Thomas C. A. , Campbell E. M. , Baker K. L. , Casey D. T. , Hohenberger M. , Kritcher A. L. , Spears B. K. , Khan S. F. , Nora R. , Woods D. T. , Milovich J. L. , Berger R. L. , Strozzi D. , Ho D. D. , Clark D. , Bachmann B. , Benedetti L. R. , Bionta R. , Celliers P. M. , Fittinghoff D. N. , Grim G. , Hatarik R. , Izumi N. , Kyrala G. , Ma T. , Millot M. , Nagel S. R. , Patel P. K. , Yeamans C. , Nikroo A. , Tabak M. , Gatu Johnson M. , Volegov P. L. , Finnegan S. M.
Published: November 2020

Progress in inertial confinement fusion depends on the accurate interpretation of experiments that are complex and difficult to explain with simulations. Results could depend on small changes in the laser pulse or target or physics that are not fully understood or characterized. In this paper, we discuss an x-ray-driven platform [Baker et al., Phys. Rev. Lett. 121, 135001 (2018)] with fewer sources of degradation and find the fusion yield can be described as a physically motivated function of laser energy, target scale, and implosion symmetry. This platform and analysis could enable a more experimental approach to the study and optimization of implosion physics.
Combined infrared reflectance and Raman spectroscopy analysis of Si-doping limit of GaN
Authors: Ma Bei , Tang Mingchuan , Ueno Kohei , Kobayashi Atsushi , Morita Ken , Fujioka Hiroshi , Ishitani Yoshihiro
Published: November 2020

Heavily Si-doped GaN layers grown by pulsed sputtering deposition (PSD) on Fe-doped GaN/Al2O3 templates are investigated using infrared reflectance and microscopic Raman measurements. The electron densities (ne) of the Si-doped layer are found to be in the range of 3 × 1018–4 × 1020 cm−3. Signs of transition to over doping is detected for the highest-doping sample by exploiting the advantages of infrared reflectance and microscopic Raman scattering measurements, where we observe a gradual decrease in ne and the highest broadening of the Raman peak of the E2(high) phonon mode toward the surface, and also growing of an additional Raman peak toward the surface, which is attributed to the generation of cubic phase crystal. On the other hand, other samples show spatially uniform ne up to 2 × 1020 cm−3 and small strain in the whole region in the Si-doped layers. This result demonstrates the growth feasibility of highly conductive Si-doped GaN layer by the PSD method.
Long ECGs reveal rich and robust dynamical regimes in patients with frequent ectopy
Authors: Bury T. M. , Lerma C. , Bub G. , Laksman Z. , Deyell M. W. , Glass L.
Published: November 2020

We have analyzed the electrocardiographic data collected during continuous 7-day ambulatory recordings in patients with frequent premature ventricular complexes (PVCs). We analyze the dependence of the frequency and patterns of PVCs on the heart rate and the time of the day. Patients display rhythms of a complex yet consistent structure. In a given patient, the pattern remains robust over different days and particular repetitive patterns appear at specific heart rates, suggesting the appearance of bifurcations in the dynamics. Over the course of 24 h, we find that in some patients, patterns appear to depend only on the heart rate, whereas in others, both the time of the day and the heart rate play a role in controlling the dynamics. Identifying parameter values at which bifurcations occur facilitates the development of dynamical models for arrhythmia. The use of powerful recording and analysis techniques will enable improved analysis of data and better understanding of mechanisms of arrhythmia in individual patients.
Quantum dynamical simulations of intra-chain exciton diffusion in an oligo (para-phenylene vinylene) chain at finite temperature
Authors: Di Maiolo Francesco , Brey Dominik , Binder Robert , Burghardt Irene
Published: November 2020

We report on quantum dynamical simulations of exciton diffusion in an oligo(para-phenylene vinylene) chain segment with 20 repeat units (OPV-20) at finite temperature, complementary to our recent study of the same system at T = 0 K [R. Binder and I. Burghardt, J. Chem. Phys. 152, 204120 (2020)]. Accurate quantum dynamical simulations are performed using the multi-layer multi-configuration time-dependent Hartree method as applied to a site-based Hamiltonian comprising 20 electronic states of Frenkel type and 460 vibrational modes, including site-local quinoid-distortion modes along with site-correlated bond-length alternation (BLA) modes, ring torsional modes, and an explicit harmonic-oscillator bath. A first-principles parameterized Frenkel–Holstein type Hamiltonian is employed, which accounts for correlations between the ring torsional modes and the anharmonically coupled BLA coordinates located at the same junction. Thermally induced fluctuations of the torsional modes are described by a stochastic mean-field approach, and their impact on the excitonic motion is characterized in terms of the exciton mean-squared displacement. A normal diffusion regime is observed under periodic boundary conditions, apart from transient localization features. Even though the polaronic exciton species are comparatively weakly bound, exciton diffusion is found to be a coherent—rather than hopping type—process, driven by the fluctuations of the soft torsional modes. Similar to the previous observations for oligothiophenes, the evolution for the most part exhibits a near-adiabatic dynamics of local exciton ground states (LEGSs) that adjust to the local conformational dynamics. However, a second mechanism, involving resonant transitions between neighboring LEGSs, gains importance at higher temperatures.
Electronic structure parameter of nuclear magnetic quadrupole moment interaction in metal monofluorides
Authors: Talukdar Kaushik , Nayak Malaya K. , Vaval Nayana , Pal Sourav
Published: November 2020

The electronic structure parameter (WM) of the nuclear magnetic quadrupole moment (MQM) interaction in numerous open-shell metal monofluorides (viz., MgF, CaF, SrF, BaF, RaF, and PbF) is computed in the fully relativistic coupled-cluster framework. The electron-correlation effects are found to be very important for the precise calculation of WM in the studied molecular systems. The molecular MQM interaction parameter scales nearly as Z2 in the alkaline earth metal monofluorides, where Z is the nuclear charge of metal. Our study identifies 223RaF as a good candidate for the experimental search of the nuclear MQM, which can help unravel the physics beyond the standard model in the hadron sector of matter.
Elucidation of pH impacts on monosubstituted benzene derivatives using normal Raman and surface-enhanced Raman scattering
Authors: Xi Wenjing , Haes Amanda J.
Published: November 2020

Raman spectral vibrational frequencies are used to probe the local chemical environment surrounding molecules in solution and adsorbed to gold nanostars. Herein, the impacts of functional group protonation on monosubstituted benzene derivatives with amine, carboxylic acid, or hydroxide are evaluated. Changes in binding affinity and orientation are apparent by evaluating systematic variations in vibrational frequencies. Notably, the electron donating abilities of these functional groups influence the vibrational frequency of the ring breathing mode, thus leading to improved spectral interpretation. Furthermore, gold nanostars are used to investigate the impact of molecular protonation on the adsorption of benzoic acid/benzoate to gold. The changes in molecular protonation are measured using zeta potential and the surface-sensitive technique, surface-enhanced Raman scattering. These methods reveal that pH variations induce carboxylate protonation and electron redistribution that weaken molecular affinity, thereby causing the molecule to adopt a perpendicular to parallel orientation with respect to the nanostar surface. Functional group identity influences the ring breathing mode frequency as a function of changes in electron donation from the functional group to the ring in solution as well as molecular affinity to and orientation on gold. This exploitation of vibrational frequencies facilitates the elucidation of molecule behavior in complex systems.
Fundamental gap of fluorographene by many-body GW and fixed-node diffusion Monte Carlo methods
Authors: Dubecký Matúš , Karlický František , Minárik Stanislav , Mitas Lubos
Published: November 2020

Fluorographene (FG) is a promising graphene-derived material with a large bandgap. Currently existing predictions of its fundamental gap (Δf) and optical gap (Δopt) significantly vary when compared with experiment. We provide here an ultimate benchmark of Δf for FG by many-body GW and fixed-node diffusion Monte Carlo (FNDMC) methods. Both approaches independently arrive at Δf ≈ 7.1 ± 0.1 eV. In addition, the Bethe–Salpeter equation enabled us to determine the first exciton binding energy, Eb = 1.92 eV. We also point to the possible misinterpretation problem of the results obtained for gaps of solids by FNDMC with single-reference trial wave functions of Bloch orbitals. We argue why instead of Δopt, in the thermodynamic limit, such an approach results in energy differences that rather correspond to Δf, and we also outline conditions when this case actually applies.
On-the-fly ab initio semiclassical evaluation of third-order response functions for two-dimensional electronic spectroscopy
Authors: Begušić Tomislav , Vaníček Jiří
Published: November 2020

Ab initio computation of two-dimensional electronic spectra is an expanding field, whose goal is improving upon simple, few-dimensional models often employed to explain experiments. Here, we propose an accurate and computationally affordable approach, based on the single-trajectory semiclassical thawed Gaussian approximation, to evaluate two-dimensional electronic spectra. Importantly, the method is exact for arbitrary harmonic potentials with mode displacement, changes in the mode frequencies, and inter-mode coupling (Duschinsky effect), but can also account partially for the anharmonicity of the involved potential energy surfaces. We test its accuracy on a set of model Morse potentials and use it to study anharmonicity and Duschinsky effects on the linear and two-dimensional electronic spectra of phenol. We find that in this molecule, the anharmonicity effects are weak, whereas the Duschinsky rotation and the changes in the mode frequencies must be included in accurate simulations. In contrast, the widely used displaced harmonic oscillator model captures only the basic physics of the problem but fails to reproduce the correct vibronic lineshape.
The more the merrier: unparalleled sympatric species richness in a sea spider genus (Pycnogonida : Callipallenidae : Pallenella) from Tasmanian waters
Authors: Brenneis Georg , Arango Claudia P. , Sharma Prashant P. , Schwentner Martin
Published: November 2020

Southern Australian waters feature remarkably diverse assemblages of the sea spider family Callipallenidae Hilton, 1942. The most speciose of the three Australian-endemic genera currently recognised has been known as Meridionale Staples, 2014, but is here reinstated under the name Pallenella Schimkewitsch, 1909 based on its type species Pallenella laevis (Hoek, 1881). This genus includes several brightly coloured forms that occur in high abundance on arborescent bryozoans. However, considerable similarity of congeners and scarcity of diagnostic characters continue to render species delineation in this genus challenging. Using an integrative taxonomic approach, we combine detailed morphological investigation with analysis of two genetic markers (mitochondrial cytochrome c oxidase subunit I, and nuclear rDNA including internal transcribed spacers 1 and 2) to explore the extraordinary species richness of the genus Pallenella in south-east Tasmania. In agreement with our morphology-based segregation of different species and morphotypes, we recovered well-supported corresponding clades in the genetic analyses. Strong mito-nuclear concordance in the two markers supports the inference of sustained reproductive isolation between the sympatrically occurring forms. Based on these findings, we distinguish a total of 13 Tasmanian congeners, representing the most diverse assemblage of sympatric species in the same microhabitat reported for a single pycnogonid genus. Within this assemblage, we (1) record the type species P. laevis for the first time after almost 150 years, (2) delineate the two Tasmanian morphotypes of the provisional ‘variabilis’ complex, and (3) describe two species new to science (P. karenae, sp. nov., P. baroni, sp. nov.). Despite considerable genetic divergences between most congeners, only few and often subtle characters are found to be suitable for morphology-based delineation. Notably, colouration of living specimens is suggested to be informative in some cases. For morphology-based species identification of preserved specimens, a key relying on combinations of characters rather than single diagnostic features is proposed.
Egg laying and embryo development of Octopus huttoni in response to temperature and season
Authors: Donlon Erica M. Y. , McKinnon Jean F. , Lamare Miles D.
Published: November 2020

Basic life history information, such as reproductive strategy and embryo development, are lacking in many octopus species, including in the New Zealand species Octopus huttoni. Octopus paralarvae are particularly sensitive to changing temperatures; therefore, this study aimed to determine how temperature affects the egg-laying behaviour and embryo development and the implications on O. huttoni paralarvae survivability in southern New Zealand is discussed. Reproduction was found to occur all year-round, but there was a tendency to lay eggs in the spring and summer, most likely due to the increase in planktonic food production during this time of year. An inverse relationship was observed between temperature and duration of embryo development, in which the shortest duration was 44 days at a mean temperature of 17.3°C and the longest was 158 days at a mean temperature of 12.7°C. It is unknown how this increase in temperature and decrease in development time affects the survivability of the resulting individual, but studies from other species of octopus suggest that this phenomenon can be detrimental to overall paralarval survivability.
Operationalising homeowner wildfire risk mitigation in fire-prone areas
Authors: Walpole Hugh , McCaffrey Sarah , Rapp Claire , Wilson Robyn
Published: November 2020

A significant amount of research has examined what motivates people living in fire-prone areas to mitigate their wildfire risk (i.e. engage in activities that reduce vulnerability and the effects of a wildfire on an individual’s property). However, drawing overarching conclusions from this research is difficult because of the myriad of ways researchers have measured and analysed wildfire risk mitigation. Although recommendations exist for measuring risk-mitigation activities, no research to date has based these recommendations on an examination of how different operationalisations influence subsequent interpretations of homeowner preparedness. We addressed this gap by examining how the effects of demographics and contextual factors on preparedness differ across different ways of counting the amount of vegetation management completed. We also examined how different statistical approaches influence the results. We found that measuring vegetation management as the sum of activities completed is problematic and can obfuscate important relationships. For example, age is positively related to the proportion of applicable activities completed, but not the total number. We recommend assessing which items are applicable to respondents and constructing proportional measures rather than sums. We also recommend that, given the need for maintenance of vegetation, researchers use non-binary measures that allow respondents to indicate how much work they have undertaken towards each activity.
Sobre los pares aspectuales en polaco
Authors: Wilk-Racięska Janna
Published: November 2020

El artículo aborda las relaciones fundamentales entre los verdaderos pares aspectuales polacos, es decir, los que
representan única y exclusivamente las relaciones terminativas. Además se describe la estrecha relación existente entre la formación de
estos pares y el aspecto léxico. El estudio, asentado en las investigaciones más recientes de los aspectólogos eslavos (polacos, rusos,
etc.,), expone unas regularidades que permiten desmitificar por lo menos una parte del aspecto eslavo. A fin de confirmar su validez cada
análisis va ilustrado con unos ejemplos extraídos de los libros y revistas en español y en polaco, así como del Diario Oficial de la Unión
Europea (versiones española DO UE y polaca DU UE).
Wormhole solutions with scalar field and electric charge in modified gravity
Authors: Godani Nisha , Samanta Gauranga C
Published: November 2020

In this paper, we have considered the modification of general relativity and presence of extra matter part for the exploration of traversable wormhole solutions. In particular, we have considered the background of f(R, T) gravity under the effect of scalar field and electric charge, which play the role of additional matter part. The energy conditions are detected in the presence of both scalar field and electric charge and the results are compared. Further, the existence of photon spheres, due to the strong gravitational lensing, is examined and the formation of relativistic images is studied.
Development and prospects for the introduction of a low-emission combustion system for ground-based gas turbine engines and gas turbine units
Authors: Biryuk V V , Vorotyntsev I E , Tyulkin D D , Tsybizov Yu I
Published: November 2020

Today, more and more “stringent” requirements are established in the world for the emission of harmful substances in the combustion products of gas turbines operated and newly developed, which is why the issue of ensuring environmental safety is relevant. The article presents the basic principles of organizing low - emission fuel combustion based on a generalization of experience in the successful operation of gas turbines of the NK family, which ensured that modern requirements for reliability and environmental safety are met. An example is given of the modernization of the gas turbine combustion chamber in order to reduce the levels of emissions of harmful substances. The experience of introducing into serial production of additive technology for the manufacture of basic elements of low-emission combustion chamber using selective laser melting technology is described.
Experimental and numerical study of the interaction of subcooled water with saturated steam in a horizontal pipe
Authors: Volkov G J , Kapustin A V , Melikhov V I , Melikhov O I , Nikonov S M , Baybakov V D
Published: November 2020

Interaction of subcooled water with saturated steam in horizontal tube can produce so-called condensation induced water hammers, which may be dangerous for integrity of NPP equipment. This phenomenon has been investigated at the special test facility developed at Electrogorsk Research and Engineering Center. Test section of the test facility is horizontal tube of inner diameter of 64 mm and a length of 3 m. It has been performed several experimental runs, where subcooled water was supplied to the end of the tube filled by saturated steam. Another end of the tube was connected to separator vessel. System pressure, water subcooling and water flow rate were variable parameters. There were a lot of condensation induced water hammers, observed during experiments. Experimental data have been analysed with thermal-hydraulic codes WAHA and RELAP5, based on two-phase, two-fluid model.
The blast air preheating of an power boiler CHP ZIGM
Authors: Ziganshina S K , Kudinov A A
Published: November 2020

To improve the efficiency of the steam-turbine thermal power plant by reducing heat loss in a cold source by regenerating part of the heat of condensation of steam exhaust in the turbine, it is proposed to preheat the boiler blast air in a heat exchanger with circulating water heated in a steam turbine condenser. Saving of heat energy in monetary terms due to the use of part of the heat of condensation of steam in the turbine during preheating of the blast air of the ener-gy boiler BKZ-420-140 NGM of the Samara Thermal Power Plant to 20 °C is 13.244 mln rub/year. The design of an air-preheating unit for preheating the blast air of the power boiler BKZ-420-140 NGM has been developed, in which the heating coolant is circulating water heated in a steam turbine condenser. Variant calculations were carried out, as a result of which the main thermal performance parameters of the installation were determined at different boiler loads and outdoor temperatures.
Economic efficiency evaluation of applying the general-purpose heat and power plant based on the reciprocating steam engine
Authors: Razuvaev A V , Kobzev R A , Ya Redko I
Published: November 2020

The paper presents the application perspectives of the general-purpose heat and power plant based on the reciprocating steam engine for driving various mechanisms. Renewable energy sources are used as fuel for the plant operation. The economic efficiency estimating calculation results of the proposed general-purpose heat and power plant on site are represented.
Analysis of the experiment KROTOS-44 of melt-water explosive interaction using the code VAPEX
Authors: Melikhov V I , Melikhov O I , Saleh B , Shkel A A , Alkhutov M S
Published: November 2020

The basic aim of KROTOS test facility is to provide experimental data on fuel coolant interaction phenomena during severe accidents in nuclear power plants. The presented article is devoted to validate the VAPEX code developed at the Department of NPP in Moscow Power Engineering Institute. The experiment K-44 was simulated using the VAPEX code, this experiment has a significant importance because it allows to clearly observe the growth and propagation of pressure waves. The calculated data for the explosion stage obtained by the VAPEX code are in a good agreement with the experimental data, which confirms the adequacy of the VAPEX code for the analysis of fuel coolant interaction in case of severe accidents in nuclear power plants.
Remote area power supply system for oil leakage detection systems and stop valves drives for pipelines
Authors: Belsky A A , Yu Glukhanich D , Ivanchenko D I
Published: November 2020

This paper describes problem of electrical power supply of data collection points for leakage detection and stop valve control systems, designed for emergency shutoff of fault parts of oil pipelines in areas without centralized power supply. Autonomous electrical power supply complex, based on thermoelectric generators and photovoltaic panels, was proposed as a solution. Structure and parametric sufficiency of power supply system were established. Computer model for estimation of autonomous power system effectiveness was developed and validated.
Application peculiarities of the high-temperature fluids containing nanoparticles in gas-tube boilers
Authors: Slobodina E N , Mikhailov A G
Published: November 2020

The paper considers the application peculiarities of the high-temperature fluids containing nanoparticles in gas-tube boilers. The classification of nanofluids obtaining methods is presented, one-step and two-stepmethods for preparing the product are considered. The main thermophysical properties of materials are described. The values of the thermal conductivity coefficient for some materials that are usually used as the base ones for mixing liquids and nanoparticles are represented. The mechanisms of heat transfer in nanofluids in the forced and free convection and boiling processes determining the gas-tube boiler efficiency are considered. Criteria dependences of calculating the heat transfer in the free and forced convection and boiling when nanofluids flowing through the heat generators are proposed. It is proved that when adding nanoparticles to the base liquid, an increase in the heat transfer coefficient will be observed if its thermal conductivity is increased. Besides, the convective heat transfer is affected by the density and viscosity of the nanofluid. When the liquid boils, the critical heat flux increases, and the determining factor of the heat transfer coefficient is the particles concentration. The represented data are prerequisites of developing the efficient gas-tube boiler with a high-temperature fluid.
A numerical simulation of hydrogen-oxygen mixture combustion in a water-cooled combustion chamber
Authors: Egorov A N , Ryzhkov A A
Published: November 2020

The efficiency of hydrogen combustion in an oxygen environment under various conditions is considered as a fundamental part of the nuclear power plant combination with hydrogen technology. The paper analyses two computational models: The Chemical Equilibrium and Steady Diffusion Flamelet models. A numerical simulation of the hydrogen-oxygen mixture combustion at stoichiometric conditions and heat transfer process in a water-cooled combustion chamber has been performed. It is shown that the most efficient hydrogen combustion is at a pressure of 6 MPa for both models. Additionally, the peak temperature of the cooling water is observed at a pressure of around 1.75 MPa. It is established that the Steady Diffusion Flamelet model has an advantage over the Chemical Equilibrium model while the use of the latter can fail to predict a correct combustion profile.
Feasibility of hydrogen-air energy storage gas turbine system for the solar power plant in Yakutsk region
Authors: Chukhin N I , Schastlivtsev A I , Shmatov D P
Published: November 2020

For the solar power plants unsteady power generation is one of the main drawbacks, which must be taken into account. The hydrogen-air energy storage gas turbine system is considered in this paper for the Yakutsk region in Russia. This place with no centralised electrical grid has enough solar insolation level to supply with the power the settlement of several households with the average power consumption of 3 kW. The calculations show that 52 photovoltaic panels of the specific type are optimal number from the power balance data. It is supposed that in the months with the surplus of solar power the system works in generation mode and in the other months in storage mode. Also some reserve is planned for the supply during night in the storage mode by the gel batteries. After that the volumes and masses were determined for the reservoirs containing air, hydrogen and oxygen for the energy storage. The air reservoir for the compressed air energy storage (CAES) has the biggest volume 121 m3 according to the calculations. The gas turbine (GT) of 5 kW suits the system in the power generation mode. The special hydrogen-air combustion chamber is required for the GT unit.
Reliability assessment of emergency auxiliaries of an NPP using an additional steam turbine under various modes of its utilization
Authors: Aminov R Z , Yurin V E
Published: November 2020

Under complete blackout of a station, it is possible to cool-down the VVER-1000 type reactors using the energy of residual heat release of the reactors. The calculations from past works showed in the context of Balakovo nuclear power plant, that a single low-power steam-turbine unit by utilizing the energy of residual heat release from one reactor is capable to provide electricity for two VVER-1000 power units, including the cases when the first circuit in one of the units is depressurized. This work is a continuation of the investigation of the general-station reserve systems for nuclear power plants own needs. The effectiveness of the joint installation of an additional multifunctional steam turbine and a mobile general-station diesel generator was investigated taking into account the results of a large research of the causes for not starting diesel generators at nuclear power plants, conducted by scientists from the USA and Canada, according to which the interval of the percentage of their non-start ranges from 1 to 3%. It is shown that the reliability of such concurrent redundancy of the NPP’s own needs meets the IAEA requirements. Also in the work, the reliability of the developed emergency power supply system was investigated in the conditions of the additional steam turbine stop during the night off-peak hours of the electrical load. Research has shown that this is not acceptable for the accepted conditions from a safety point of view.
Thermal calculation and experimental corroboration of counter-flow tube-type evaporators and condensers of heat pumps operating on zeotropic mixtures
Authors: Usachev A P , Rulev A V , Yu Usacheva E , Shurayts A L
Published: November 2020

When using renewable heat sources that have limited volumetric heat capacity, for example, air, water, gases, the temperature of which changes significantly during cooling in the evaporator and heating in the condenser, execution of cycles for heat pumps operating on zeotropic mixtures, the temperature of which also changes, makes it possible to increase their energy efficiency. The paper proposes a technique for thermal calculation of counter-flow tube-type evaporators and heat pump condensers which use media with limited volumetric heat capacity as heat sources, and zeotropic mixtures as working substances. We carried out experimental corroboration of the proposed technique for thermal calculation of counter-flow tube-type evaporators and heat pump condensers, which confirms the validity of the developed mathematical equations of heat transfer in the “medium with limited volumetric heat capacity, i.e. propane-butane zeotropic mixture” system. Average deviation of experimental data from theoretical dependencies with a confidence level of 95% is 27.6%, which makes it possible to recommend them for use in design and operational practice.
A condition of reliability improvement of the system based on the fog-computing concept
Authors: Melnik E V , Klimenko A B
Published: November 2020

In this paper, the effect of the fog-computing concept, applied to the information and control systems, is considered. A special condition of the fog-computing application expediency has been developed. It has been proved that the system reliability improvement is reachable using the fog-computing concept, if the workload shifted to the fog nodes does not exceed the workload conducted by the transit data transmission. In this case the application of the fog-computing concept is expedient and useful. Some simulations, which illustrate the condition proposed, were conducted in this paper.
Mathematical model of the interaction of plasma with the inner surface of a hollow cathode in a vacuum plasma torch
Authors: Anshakov A S , Cherednichenko A V , Cherednichenko M V , Serikov V A
Published: November 2020

The analysis of the equation of energy balance on the inner surface of a hollow cathode enabled us to establish a decline in electric current in the cathode down to zero value, taking place due to the interaction of the electronic component of plasma with its magnetic field. A formula of the depth of plasma influx inside the cathode channel was developed. The spatial position of the active zone and the current density on the surface of the current transfer were determined using an experimental dependency.
Development of a conceptual model and methods for multi-agent state assessment of technogenic systems
Authors: Bugakova T Y
Published: November 2020

For geodetic monitoring of the spatial-temporal states of technogenic systems under the conditions of hazardous processes that are fast-moving in time, the speed of obtaining objective information and minimizing the human factor are important, which contributes to the timely adoption of the most effective solutions. This is possible by using modern digital technologies based on multi-agent systems, methods of intellectualization and robotization. Based on the analysis of the state of the geodetic monitoring problem, spatial-temporal states of technogenic systems, a conceptual model and methods of multi-agent state assessment are proposed, which will minimize the human factor and significantly improve the quality and speed of obtaining an active information function for timely management decisions in the context of fast-moving processes and emergency prevention.
On simulation of the photon wave function to explain the Young’s experiment and prospects for its use in quantum cryptography
Authors: Davydov A P , Zlydneva T P
Published: November 2020

The method developed in previous works for building the photon wave function in configuration representation is briefly described. The simulation of such function (wave packet) appropriate to femtosecond laser radiation, using the distribution of Gauss of photon momenta in the state of a single laser impulse is expounded. By other appropriate simulated wave function of photon the light interference in Young’s experiment is explained within the frame of quantum mechanics without the attraction of transition probability amplitudes used in approach of quantum electrodynamics. This allows us considering interference phenomena for photons and particles from the same basis of the quantum-mechanical principle of superposition employed to the wave function built in the configuration space. Using the building apparatus of photon quantum mechanics, the Malus law postulated in quantum theory is justified. The relevance of new experiments to study the interaction of quantum objects between themselves and the physical vacuum, which would reveal the origins of the mathematical description of quantum states using the wave function of these quantum objects, is substantiated. It is suggested that the ideas of constructing the wave function of a free photon in the coordinate representation can find relevance in the field of quantum cryptography.
Comparative analysis and experimental verification of simulation modelling approach in MATLAB-Simulink and SimInTech
Authors: Domakhin E A , SPopov N , Vilberger M E , Anibroev V I , Singizin I I
Published: November 2020

The paper considers a simulation modelling approach validity for the control system development of real objects. Two programs for research were used then experimentally validated. The experiment showed good repeatability between software and revealed the permissible limits for a simulation modelling approach use.
Solution of transport safety problems based on biometric systems with error-correcting coding procedures
Authors: Gladkikh A A , Volkov A K , Volkov A K , Damdam M A Y , Al-Mesri Ali S A
Published: November 2020

The paper considers models and methods for solving processing biometric data at the physical and channel levels. A classification of the parameters of such systems is given and those characteristics that play a decisive role in achieving the objective function in limited time intervals are distinguished from them. The work aims to analyze the possibilities of increasing the reliability of biometric devices at the channel level by using error correction codes. The practicability and necessity of error-correcting coding mean using the permutation data decoding algorithms capable of matching biometric identification adequately. Based on the results of statistical modelling of optical communication channels, the necessary and sufficient conditions for the application of permutation decoding tools for binary codes are determined. The problem of minimizing the memory size of the cognitive map of a permutation decoder is solved by allocating the permutation orbits and using the generating combinations of loops as indexes of the reference matrices. An efficient algorithm is proposed for finding a unique orbit number and the corresponding reference matrix when the receiver generates an arbitrary permutation of characters from the set of permissible permutations.
Application of theory of multi-agent systems for operational geodetic monitoring of technogenic objects
Authors: Knol I A , Bugakova T Yu , Rozhkova M V
Published: November 2020

The analysis of modern methods of geodetic monitoring of technogenic objects (TO) in geodesy is carried out in the paper. The information on the use of robotic devices in geodetic monitoring of technogenic objects is given. The application of the theory of multi-agent systems for the operational geodetic monitoring of technogenic objects is proposed. The concept of geodetic robot “georobot” is formulated as an intelligent robotic device capable of increasing the speed of obtaining data on the spatial-temporal state of technogenic objects in extreme conditions without human intervention, increasing the reliability of geodetic monitoring and reducing the risk of emergencies. To determine the flight path of the georobot, the categories of technogenic objects are analyzed and their mathematical formalization is carried out to a set of characteristic volumetric geometric figures. A comparative table has been drawn up containing information on the categories of technogenic objects, the geometric image of the object and the path of flying around.
Analysis of the harmonic composition of the rectified voltage at the asymmetry of the secondary system of windings with different turns in converter
Authors: Neyman L A , Linnik K S
Published: November 2020

The use of integrated transformer converters of the number of phases, in which the EMF phase system at the input of bridges is formed by the geometric addition of the EMF components of individual windings, expands the scope of application of DC voltage sources with ripple frequency. With the symmetry of the transformer converter of the number of phases included in the valve bridges, each ripple of the rectified voltage of the integrated rectifier contains m ripples of exactly the same amplitude and duration, containing the corresponding composition of harmonics. However, when designing such integrated rectifiers, there is a problem of ensuring an acceptable level of symmetry of the multiphase EMF system. This is due to the inability to implement the required ratios between the numbers of turns due to their discreteness. This paper presents studies of the analysis of harmonics of rectified voltage with an asymmetry formed by a secondary system of multi-turn windings for an eight-pulse rectification scheme.
Physical picture of energy conversion during cavitation
Authors: Porsev E G , Malozyomov B V
Published: November 2020

The results of theoretical and experimental studies of heat generators that convert electrical energy into heat with a high-energy conversion coefficient are presented. A hypothesis is proposed on the origin of a highly efficient transformation in the form of a second-order phase transition with a transition of water from the cluster state to the monomolecular state and vice versa.
Methodology for modelling stochastic optimization of innovative development of enterprises using probabilistic methods
Authors: Shanin I I
Published: November 2020

The article proposes the results of a scientific study based on the construction of mathematical models of stochastic optimization using probabilistic methods aimed at the innovative development of timber industry enterprises. The construction of economic and mathematical models is a necessary direction when forecasting various processes.The construction of stochastic optimization models based on economic and mathematical modelling makes it possible to establish a number of the most significant cause-effect relationships of technological, resource and effective indicators using formalization parameters, as well as determine the nature of the likely relationship between the indicators. The most relevant from a scientific and practice-oriented point of view for modelling the dynamics of technological and innovative development of an enterprise is the application of probabilistic methods using production functions.When applying production functions, in a scientific approach, many average indicators were used, taking into account various production and technological relationships of the production process, technological solutions and innovations. Based on the methodology of stochastic optimization in the construction of production functions in the process of economic and mathematical modelling, it is possible to form an adequate production function to build the necessary mathematical model and forecast scenarios of the dynamics of innovative development of enterprises.
Computer simulation of thermal expansion of the charge of liquid nitrogen in the process of heat load
Authors: Yerezhep D , Aldiyarov A , Sokolov D , Nurmukan A
Published: November 2020

The computer simulation model of the expansion of the liquid nitrogen charge during a heat load was created, and the Mises stress criterion was considered on the basis of theoretical and experimental data. The influence of the type of using temperature load was studied to generate calculated numerical data for creating fuel on liquid nitrogen. These studies are necessary for the formation of an additional numerical experiment to study the phase transition of liquid nitrogen to a gaseous state under conditions of a closed, and then sharply increasing (exponentially) volume, which is characterized as quasi-isobaric conditions.