bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchronous frequency comparison beyond the Dick limit based on dual-excitation spectrum in an optical lattice clock
Authors: Lu Xiaotong , Zhou Chihua , Li Ting , Wang Yebing , Chang Hong
Published: December 2020

We present a synchronous frequency comparison method based on one cold-atom ensemble by using the dual-excitation spectrum technique, which can simultaneously detect the probabilities of two different clock transitions. We experimentally verify this synchronous frequency comparison method between |mF|=9/2 and |mF|=7/2 in a one-dimensional 87Sr optical lattice clock and the comparison instability is well below the Dick limit. We also extend the dual-excitation spectrum method to shorten the clock feedback cycle by a half in optical lattice clocks and experimentally demonstrate that the interleaved self-comparison instability is 1.4 times lower than that of the traditional operation method.
A modified SEIR model applied to the data of COVID-19 spread in Saudi Arabia
Authors: Youssef Hamdy M. , Alghamdi Najat A. , Ezzat Magdy A. , El-Bary Alaa A. , Shawky Ahmed M.
Published: December 2020

The Susceptible-Exposed-Infectious-Recovered (SEIR) model is an established and appropriate approach in many countries to ascertain the spread of the coronavirus disease 2019 (COVID-19) epidemic. We wished to create a new COVID-19 model to be suitable for patients in any country. In this work, a modified SEIR model was constructed. We used the real data of COVID-19 spread in Saudi Arabia for statistical analyses and complex analyses. The reproduction number and detailed review of stability demonstrated the complexities of our proposed SEIR model. The solution and equilibrium condition were explored based on Jacobian’s linearization approach to the proposed SEIR model. The state of equilibrium was demonstrated, and a stability study was conducted in the disease-free environment. The reproduction number was measured sensitively against its internal parameters. Using the Lyapunov principle of equilibrium, the overall consistency of balance of our model was demonstrated. Findings using the SEIR model and observed outcomes due to COVID-19 spread in Saudi Arabia were compared. The modified SEIR model could enable successful analyses of the spread of epidemics such as COVID-19. An “ideal protocol” comprised essential steps to help Saudi Arabia decelerate COVID-19 spread. The most important aspects are to stay at home as much as possible and for infected people to remain in an isolated zone or secure area.
Coupling solidification kinetics with phase-behavior computations in hydrodynamic simulations of high-pressure, dynamic-compression processes
Authors: Myint Philip C. , Sadigh Babak , Benedict Lorin X. , Sterbentz Dane M. , Hall Burl M. , Belof Jonathan L.
Published: December 2020

In this study, we report a numerical scheme to integrate models for the kinetics of solidification processes together with phase-behavior computations in the context of continuum-scale hydrodynamic simulations. The objective of the phase-behavior computations is to determine the pressure and temperature, given the following three sets of inputs: (1) an appropriate equation of state to describe our system, (2) the phase fraction(s) produced by the kinetic models, (3) and the volume and internal energy obtained by solving the conservation equations that govern the hydrodynamic behavior. The kinetics are assumed to be governed by the Kolmogorov–Johnson–Mehl–Avrami equation, and the nucleation and growth rates that enter into that equation are functions of the pressure and temperature produced by the phase-behavior computations. Our formulation allows for the fluid and solid phases to be at different temperatures (thermal nonequilibrium) and pressures (arising from surface-tension-induced Laplace contributions). The formulation is presented in a fairly general setting that is independent of any particular material, although we demonstrate it in some examples related to high-energy-density science applications where materials are rapidly compressed to pressures exceeding several gigapascals in less than a microsecond. We conclude with a critical evaluation of our approach and provide suggestions for future work to improve the predictive capabilities and generality of the models.
Clinically approved IVIg delivered to the hippocampus with focused ultrasound promotes neurogenesis in a model of Alzheimer’s disease
Authors: Dubey Sonam , Heinen Stefan , Krantic Slavica , McLaurin JoAnne , Branch Donald R. , Hynynen Kullervo , Aubert Isabelle
Published: December 2020

Significance

The efficacy of immunotherapy in Alzheimer’s disease is limited, partly because antibodies, administered peripherally, have poor access to the brain. Focused ultrasound (FUS) with microbubbles allows the passage of antibodies from the blood to the brain. In a mouse model of Alzheimer’s disease, antibodies administered in the blood, with and without FUS, reduced amyloid pathology. In contrast, FUS was required to deliver sufficient antibodies to the hippocampus and effectively promote neurogenesis. Neurogenesis, a regenerative process involved in memory functions, is impaired in Alzheimer’s disease. Putative contributors to the stimulation of neurogenesis include a decrease in the proinflammatory cytokine TNF-α. FUS holds potential to increase the efficacy of immunotherapy for Alzheimer’s disease.
The ARF tumor suppressor targets PPM1G/PP2Cγ to counteract NF-κB transcription tuning cell survival and the inflammatory response
Authors: Hyder Usman , McCann Jennifer L. , Wang Jinli , Fung Victor , Bayo Juan , D’Orso Iván
Published: December 2020

Significance

The NF-κB signaling pathway is critical for cellular responses to cell-extrinsic insults. Its dysregulation impacts cancer patients’ survival and response to available therapeutics. NF-κB utilizes the PPM1G phosphatase as a coactivator to induce inflammatory and cell survival programs in response to proinflammatory cytokines. However, how PPM1G activity is regulated to facilitate tunable control and insult resolution remains enigmatic. We take advantage of biochemical and genetic approaches and patient tumor data analysis to reveal a key function of the p14
ARF
tumor suppressor in targeting PPM1G to negatively tune NF-κB transcriptional function, thereby controlling inflammatory and apoptotic responses. We propose that PPM1G emerges as a therapeutic target in a variety of cancers arising from ARF loss of function to oncogenic NF-κB activation.
Why wild giant pandas frequently roll in horse manure
Authors: Zhou Wenliang , Yang Shilong , Li Bowen , Nie Yonggang , Luo Anna , Huang Guangping , Liu Xuefeng , Lai Ren , Wei Fuwen
Published: December 2020

Significance

In nature, it is extremely rare to observe attraction to fecal matter between wild mammalian species. Horse manure rolling (HMR) behavior described in this study is frequently observed in QIN pandas at low habitat temperature. Based on integrated analysis from climatic data, animal behaviors, and molecular assays, HMR is found as a temperature-, chemical-, and TRPM8-related behavior that may contribute to pandas’ cold tolerance. This study sheds light on how wild animals actively seek and utilize potential chemical resources from their habitat for survival adaptation.
Early specialized maritime and maize economies on the north coast of Peru
Authors: Tung Tiffiny A. , Dillehay Tom D. , Feranec Robert S. , DeSantis Larisa R. G.
Published: December 2020

Significance

The manner in which early human populations in the Americas organized their subsistence strategies and exchange have profound implications on their socioeconomic organization. Analysis of two coexisting Preceramic communities in coastal Peru (∼7,500 to 4,000 calibrated [cal] B.P.) shows that despite their proximity, they ate distinct foods. Huaca Prieta focused on marine resources, Paredones on maize and other crops. They exchanged food items, indicating early forms of cooperation among specialized Preceramic groups. Paredones shows regular maize consumption by 6,500 to 6,000 cal B.P. and maize as a staple by 5,000 to 4,500 cal B.P., particularly as a weaning food. Research on ancient political economies should incorporate isotopic and dental microwear texture data to reveal actual food consumption of the people.
Crystal structure of the FERM-folded talin head reveals the determinants for integrin binding
Authors: Zhang Pingfeng , Azizi Latifeh , Kukkurainen Sampo , Gao Tong , Baikoghli Mo , Jacquier Marie-Claude , Sun Yijuan , Määttä Juha A. E. , Cheng R. Holland , Wehrle-Haller Bernhard , Hytönen Vesa P. , Wu Jinhua
Published: December 2020

Significance

Although efforts have been made to determine the structure of talin and the way it interacts with integrins through the “head” domain, our work shows now that many of the previous mechanistic models based on the talin adapter are likely to be misleading as they are constructed on a crystal structure representing an improperly folded talin head domain. In this work, we identified the problem with the current talin head model and proposed a FERM-folded talin head. By analyzing these structural features of the FERM-folded talin head in a cellular context, involving also the kindlin adapter, we are making a critical and unprecedented contribution to the understanding and regulation of cell-matrix adhesions.
Comparing crime rates between undocumented immigrants, legal immigrants, and native-born US citizens in Texas
Authors: Light Michael T. , He Jingying , Robey Jason P.
Published: December 2020

Significance

Despite its centrality to public and political discourse, we lack even basic information on fundamental questions regarding undocumented immigrants and crime. This stems largely from data constraints. Going beyond existing research, we utilize data from the Texas Department of Public Safety, which checks and records the immigration status of all arrestees throughout the state. Contrary to public perception, we observe considerably lower felony arrest rates among undocumented immigrants compared to legal immigrants and native-born US citizens and find no evidence that undocumented criminality has increased in recent years. Our findings help us understand why the most aggressive immigrant removal programs have not delivered on their crime reduction promises and are unlikely to do so in the future.
Upregulation of a
KN1
homolog by transposon insertion promotes leafy head development in lettuce
Authors: Yu Changchun , Yan Chenghuan , Liu Yuling , Liu Yali , Jia Yue , Lavelle Dean , An Guanghui , Zhang Weiyi , Zhang Lei , Han Rongkui , Larkin Robert M. , Chen Jiongjiong , Michelmore Richard W. , Kuang Hanhui
Published: December 2020

Significance

Heading, which facilitates harvest and contributes to taste and shelf life, is an important trait in some vegetable crops. However, litter is known about its genetic and molecular mechanism. Here, we report the genetic cloning of a key regulator (
LsKN1
) of heading in lettuce, which is homologous to the
knotted 1
(
KN1
) gene in maize. The
LsKN1
gene is upregulated by the insertion of a CACTA-like transposon. Its enhanced expression suppressed the
LsAS1
gene and consequently altered leaf polarity and led to a heading phenotype.
Translation in the UK language classroom
Authors: Barnes Katrina
Published: December 2020

Pedagogical translation in UK secondary school language classrooms appears to have returned to favour after years of demonisation brought about by Grammar Translation pedagogy and the rise of L2-only approaches. This renewed interest is reflected in the recent inclusion of translation in the reading and writing sections of GCSE exams (taken by students in all countries within the UK except Scotland). However, there is still some uncertainty around how translation is perceived and utilised in the language classroom. What function has translation been thus far ascribed within language education? What could it be used to achieve? This article presents an overview of where translation currently sits within the secondary Modern Foreign Languages (MFL) landscape in the UK. It then examines how translation may be redefined as ‘dynamic’ and used as a communicative, creative activity to aid students with various aspects of their language learning. Examples of such activities are provided and explained. Finally, recommendations are made as to how to make Dynamic Translation accessible to students in future, namely through task-based translation projects and new forms of pedagogical translation assessment.
Microstructural aging and property degradation of service-exposed 1Cr–1/2Mo Coke Drum steel
Authors: Li Leijun , Kannan Rangasayee , Wang Yiyu , Sharma Nitin
Published: December 2020

After long-term service, boat samples of 1Cr-1/2Mo steel seemed to have aged, evidenced by the spheroidisation of carbides in the pearlite region, and a dispersion of fine M23C6 precipitation in the ferrite matrix. The yield strength of the cracked boat samples was two to three times the reported values of new A387 Grade 12 Class 2 material. The ductility is less than 0.5 times the reported values of the new grade. The intergranular fracture mode was likely due to the fine carbide precipitation inside the ferrite grains that strengthened the metal matrix, and the coarse intergranular CrMo-rich carbides that weaken the precipitate/grain boundary interfaces. Cavities similar to creep were observed along the grain boundaries in some of the boat samples, suggesting a possible creep-oxidation damage mechanism for coke drum steels.
“Conserved charges” of the Bondi-Metzner-Sachs algebra in the Brans-Dicke theory *
Authors: Hou Shaoqi , Zhu Zong-Hong
Published: December 2020

The asymptotic symmetries in the Brans-Dicke theory are analyzed using Penrose's conformal completion method, which is independent of the coordinate system used. These symmetries, indeed, include supertranslations and Lorentz transformations for an asymptotically flat spacetime. With the Wald-Zoupas formalism, “conserved charges” and fluxes of the Bondi-Metzner-Sachs algebra are computed. The scalar degree of freedom contributes only to the Lorentz boost charge, even though it plays a role in various fluxes. The flux-balance laws are further applied to constrain the displacement memory, spin memory, and center-of-mass memory effects.
Wind loads on buildings in tandem arrangement
Authors: Korobkov S V , Gnyrya A I , Terekhov V I
Published: December 2020

The paper presents the research results of the distribution of the local and integral pressure coefficients over the sides of the square prisms arranged in tandem and experiencing the airflow. The correlation is shown between the obtained airflow patterns and the pressure coefficient distribution; the dependences are obtained between the building arrangement and the distribution of the pressure coefficients; the phenomena caused by the airflow interaction are described in this paper.
Features of thermomechanics of pulsating gas flows in intake systems with grooves in relation to turbocharged engines
Authors: Plotnikov L V , Zhilkin B P , Brodov Yu M
Published: December 2020

Reciprocating engines (RICE) are widely used as heat engines to convert the chemical energy of fuel into mechanical work on the crankshaft. Aerodynamic and thermophysical processes in gas exchange systems significantly affect the efficiency of internal combustion RICEs. This article explores the possibility of influencing the gas dynamics and heat transfer of pulsating gas flows in the intake system by placing a channel with grooves. It is known that the presence of grooves in the channel leads to the formation of significant secondary vortices, which radically change the physical picture of the gas flow. The studies are carried out on a laboratory bench, which was a single-cylinder model of a turbocharged RICE. The system of measurements of basic physical quantities is described, taking into account their high dynamics in gas exchange systems. The experimental data processing techniques are presented. Primary data on the instantaneous values of the gas-dynamic and heat-exchange characteristics of pulsating flows are reported. It is established that the presence of a channel with grooves in the intake system leads to a decrease in the turbulence number by 40% and the intensification of heat transfer in the range of 5-50% compared with the basic intake system. A positive effect is shown in the form of an increase in engine power by 3% when using an upgraded system.
Experimental study of the gas-liquid flow characteristics in a rectangular channel with a large aspect ratio
Authors: Bartkus G V , Kuznetsov V V
Published: December 2020

This paper experimental studies the gas-liquid flow in a rectangular slit microchannel with cross-section of 200 × 2045 μm. Ethanol and nitrogen are used as working liquids and gas, respectively. The microchannel with an internal symmetric hydraulic focusing mixer is used for the study of the flow pattern for elongated bubble and transition flows. For the study of the wave patterns in the liquid film, the microchannel with an external mixer is applied. Experimental data on flow patterns are obtained using high-speed visualization and laser-induced fluorescence (LIF) methods. Using method LIF for elongated bubble and transition flows the local film thickness is measured and compared with Taylor law. For microchannel with an external mixer, the local liquid film thickness is measured for a wavy film at high gas velocity, and the wave influence on local film distribution is discussed.
Structure of stationary gas slug in an annular channel
Authors: Kashinsky O N , Kurdumov A S
Published: December 2020

Experimental study of liquid flow structure around a stationary gas slug in an annular channel was performed. The channel consisted of two concentric pipes with the diameters of 32 and 10 mm. Slug was produced in a downward liquid flow in an annular channel. Wall shear stress distribution was measured in both walls of the channel using an electrodiffusional technique. It was shown that the shape of the slug in the annular channel differs significantly from that in a circular pipe. The distribution of wall shear stress along the slug was presented for different angular positions in the channel.
Modeling of critical filtration regimes of vapor-liquid flow
Authors: Khramtsov D P , Nekrasov D A , Vyazmin A V , Pokusaev B G
Published: December 2020

Critical flows are widely used in power engineering. Such flows are characterized by non-stationary processes, active vaporization due to a sharp drop in pressure when the mixture flows from a high-pressure medium to an atmospheric pressure medium, which especially necessitates the study of the parameters of such flows in emergency situations, such as an emergency depressurization of a pipeline or cooling system. Due to the presence of two phases and the transiency of the processes, it is necessary to develop methods for numerical simulation of this process. The energy apparatus with a granular layer adds an additional level of complexity to the study of critical flows, namely, the effect of granular backfill on the characteristics of a two-phase flow. A new model for numerical simulation of the critical outflow of a vapor-liquid flow from a channel with a granular backfill has been created. The values of the mass flow rate of the mixture, the effect of vapor content on the critical flow rate, and the effect of geometric parameters of the granular backfill on the critical mass flow rate are obtained. The calculated data were compared with the experiment, and new data were obtained in a wider range of mass vapor content compared to experimental study.
The experimental and numerical study of the vertical gas movement in the cylindrical channel
Authors: Kudinov I V , Pimenov A A , Mikheeva G V
Published: December 2020

The detailed experimental and theoretical studies of the vertical gas movement through a layer of liquid (water, molten tin) placed in a cylindrical channel (10 cm diameter) were performed. It was shown that during the gas passage through a single opening (the diameter of 8 mm) its movement at a small flow takes place as single bubbles, whose diameter becomes greater as they move towards the free surface of the liquid. Increase in the diameter at identical gas and liquid temperatures is explained by the decreasing liquid pressure in the upstream direction. If the gas temperature is lower than the liquid temperature, the diameter of bubbles increases also due to gas heating, thus resulting in the increase of its pressure in the bubble. As the gas flow increases, the number of bubbles which then merge into the uniform mass in the upper part of the channel without reducing their diameter, becomes greater. When passing the gas though the diaphragm with a high number of openings (80 openings of 1 mm in diameter), the amount of bubbles becomes higher, however their diameter in the upper part of the channel practically does not increase. When using multiple strainer diaphragms arranged at small distances from each other along the channel height, the diameters of bubbles become considerably reduced, which is connected with their periodic fragmentation when passing through each subsequent strainer. Furthermore, the bubbles get the smallest diameter when they pass through the last strainer, after which the liquid and the gas make a uniform gas and liquid emulsion in the form of a mist. The analysis of the results of air passage thought the molten tin (at a temperature of 300°C) allows concluding on considerable increase in the bubble diameter as compared to the experiments with water, which is explained by gas heating in the bubbles due to a sufficiently high temperature of tin and, as a result, the increase of pressure in them. Experimental studies applicable to small-diameter cylindrical channel (2 cm) were also performed. Their analysis allows concluding about a considerable divergence of the obtained results as compared to the greater diameter channel (10 cm) at the same gas flow. For the small-diameter channel, numerical calculations were also performed (e.g. tin) in a vertical cylindrical channel (reactor) [5 – 8]. The amount of hydrogen obtained at the reactor outlet depends on the intensity of methane heating to the pyrolysis temperature. It is known that methane passes through the molten tin in the form of bubbles, whose diameter increases as they move towards the upper part of the reactor, which is connected with the reduction of upstream pressure of liquid metal as well as the increase of gas pressure in bubbles resulted from its heating. The increase in the bubble diameter makes it heating to the pyrolysis temperature difficult as a result of low heat conductivity of methane. In this regard, measures should be taken to decrease their diameter.
Vortex breakdown in a two-fluid confined flow generated in a cylindrical container
Authors: Sharifullin B. R. , Naumov I. V. , Tsoy M. A. , Shtern V. N.
Published: December 2020

Two-fluid swirling flows are rich in features of fundamental and practical interest. Among them, the most intriguing phenomenon that is important for applications is the formation of local circulation cells (vortex breakdown, VB). Our experimental study explores flows of two immiscible liquids in a sealed vertical cylindrical container driven by the rotating lid. The lid rotation generates the meridional circulation of an adjacent fluid, which serves as a rotating “liquid lid” for the lower fluid. The upper fluid goes from the cylinder axis to the periphery near the lid and back near the interface. This centrifugal circulation tends to propel the circulation in the main-fluid domain – in the lower fluid. As the angular speed of lid rotation increases, vortex breakdown occurs in the lower fluid. Using visualization of the flow and measurement of velocity by PIV method, we reveal common features of the VB development in the lower fluid at different thicknesses of the upper fluid. We show that the range of Reynolds numbers, where VB occurs, might be different depending on the volume of the upper liquid and its kinematic viscosity.
Numerical verification of heat losses in experiments with microchannel under local heating
Authors: Belosludtsev V V
Published: December 2020

With the help of three-dimensional numerical simulation in FEM software package the experimental methodology of determining heat flux and heat losses during experiments in microchannel was verified. The obtained single-phase flow data on the heat transfer coefficient and wall temperature show good agreement between numerical simulation and experimental results.
Lattice Boltzmann simulation of bubble evolution at boiling on surfaces with different wettability
Authors: Fedoseev A V , Surtaev A S , Moiseev M I , Ostapchenko A E
Published: December 2020

The hybrid Lattice Boltzmann method is adopted for a detailed study of surface wettability effects on evolution of vapor bubbles and temperature field of heat exchange surface at boiling. The simulation results show that the bubble departure diameter increases with an increase of static contact angle, and its value normalized by the capillary length approaches 3 for superlyophobic surface. In the range of contact angles of 110° – 129° the size of the dry area bounded by triple contact line greatly increases compared to the bubble departure diameter. At contact angles θ ⩾ 153° the dry area does not shrink even at the bubble departure stage and the typical film boiling regime is observed. It has been shown that the deterioration of wettability affects the evolution of the temperature field beneath the bubble, which leads to a significant change in the local heat transfer rate.
Experimental study of change of average velocity in a drop on crystalization
Authors: Morozov V S
Published: December 2020

The behavior of convection dynamics during high-temperature heating inside a drop of an aqueous solution of LiBr salt at the moment of crystalline-hydrated crust movement was studied experimentally. To measure the instantaneous velocity fields in the horizontal section of a sedentary drop, the optical PIV method was used. The measurement of convection velocity in a drop through a thick crust of crystalline hydrates did not affect the accuracy of measurements. The maximum average velocity UAv
is equal to 0.39-0.42 mm/s was realized at the initial time. Over 30-35 s the temperature gradient decreases due to heating of the solution by 3.5 times which led to a decrease in UAv
by 3-4 times. After 32 s heat transfer and evaporation enter quasi-stationary mode.
An experimental study of flow condensation with non-azeotropic refrigerant mixtures of R32/R134a in microchannels
Authors: Shamirzaev A S , Kuznetsov V V
Published: December 2020

This paper aims at experimental study of heat transfer during flow condensation of a binary mixture of refrigerants R32 and R134a in a microchannel heat exchanger. The experiments were performed in a horizontal microchannel condenser with one-sided cooling. The condenser was based on 20 × 40 mm copper plate containing 21 rectangular microchannels with a section of 335 × 930 μm. The non-azeotropic mixture of R32/R134a refrigerants at molar concentrations of the initial mixture of 35% / 65% and 65% / 35% was used as a working fluid. The experiments were carried out in the mass flow range from 100 to 300 kg/m2 s and with a vapor quality from 0.05 to 1.0 at an absolute pressure in the system of up to 14 bar. The data obtained are compared with the prediction according to Silver – Bell & Ghaly method.
Investigation of pulverized coal flaring based on eddy-resolving turbulence models
Authors: Dekterev A , Kuznetsov V
Published: December 2020

Calculation studies of the effect of the turbulent flow simulation method on the combustion processes of swirling pulverized coal flow have been performed. A comparative analysis of the results of mathematical modeling with experimental data has shown that the DES and LES methods can correctly resolve the complex vortex structure of a coal torch. It was found that the choice of turbulence simulation method when calculating the combustion of swirling pulverized coal flow has a significant impact on the results of the numerical experiment.
Exergy analysis of the potential of solar irradiation
Authors: Khoreva V A , Elistratov S L
Published: December 2020

In the study, determining the input value of the exergy of solar irradiation entering the frontal surface of the solar collector has become an issue. Several sources of information have been studied, and then a calculation method has been proposed. The article presents the calculation of the input exergy value for the exergy analysis of the solar irradiation potential. The result of the work performed is a computing program that calculates the solar energy supplied to the solar collector and can be used at any latitude and altitude above sea level.
Steam condenser for plants with carbon dioxide recovery
Authors: Milman O O
Published: December 2020

Power plants with CO2 utilization have been designed by Allam, Mateant, Turbocon, etc. One of the main problems of this plant is a condenser for steam-gas mixture with high concentration of non-condensable gas. The process of development of steam condenser for steam-gas mixture is described. Its design is based on the idea of maintaining a constant steam-gas mixture velocity along the steam condensation channel. The shape of the channel with constant SGM velocity is described. To research the heat-mass transfer of gas-team mixture the test plant with tubes crosscut by thermocouples is realized. In the process of testing, gas-steam mixture velocity, pressure and air concentration changed from 0% to 18%. The experimental results have been summarized in a dimensionless equation. The pressure drop and increase of air concentration contribute to the decrease of saturation temperature. The optimal velocity is reached when the surface area of the channel in the condenser is minimal. The optimal velocity is about 30 – 50 m/s. The research results are implemented in the experimental model of high-efficiency condenser. The heat transfer coefficient in this model is equal to about 4500 – 2700 W/(m2K) if air concentration at the inlet is 0–8 %. The designs of high-efficiency condenser for gas-steam turbine plant of 25 MW capacity and the condenser with vertical tubes have been presented.
Energy Potential of Wastewater Sludge: Economic and Ecological Efficiency
Authors: Plyaskina N I
Published: December 2020

Recently, many major cities in the world have faced a serious environmental problem caused by the presence of a large amount of waste and the established practice of their treatment. The paper presents an assessment of the energy potential of wastewater sludge (WWS) in the context of Novosibirsk city. According to our estimates, the total amount of generated semi-liquid WWS is about 132,000 tons per year, the theoretical energy output amounts to 67 GW per year, which is more than three times the total heat produced by small boiler plants in the region. Chemical compositions of WWS and stone/brown coals differ slightly. WWS contains 24.5% less carbon than coal and 5% less carbon than brown coal. The proportion of sulfur in WWS exceeds its specific content in coal by only 0.2% and in brown coal – by 4%. Seven alternative wastewater sludge utilization options have been developed, based both on new non-traditional waste incineration technologies and on finished turnkey technologies. WWS utilization options are evaluated in terms of economic efficiency, energy value, and environmental impact. The efficient option is the one associated with the utilization of WWS based on combustion with coal in a thermal power plant.
Water vapor thermal plasma generation
Authors: Anshakov A S , Radko S I , Urbakh A E
Published: December 2020

The results of studies of an electric arc plasma torch for heating water vapor are presented. For the first time, a structural diagram of a steam-water thermal plasma generator with copper electrodes was implemented. The energy characteristics of the plasma torch and erosion of the electrodes reflect the features of their behavior during combustion in a plasma-forming medium of water vapor. The results obtained indicate the promise of the developed design of the steam-water plasmatron.
An experimental investigation of the heat transfer dynamics during evaporation of a single liquid drop on a sapphire substrate
Authors: Cheverda V V , Ponomarenko T G , Marchuk I V , Karchevsky A L
Published: December 2020

The paper is devoted to an experimental study of the heat transfer dynamics during evaporation of a single liquid drop on a heated horizontal surface, which is a sapphire glass coated with a high heat-resistant black graphite paint. The method employed in research can be used to study the heat and mass transfer processes in the gas-liquid-solid contact line region with maximum heat transfer coefficient. Its particular feature as compared to the previously known methods is the solution of the initial-boundary problem for the heat conductivity equation, which in terms of mathematics is a correct problem. Using the thermography method, the sapphire surface temperature fields after single drop impingement are determined. The data obtained will be used to calculate the heat flux density in the region of the contact line of the drop.
Numerical investigation of the effect of insulator permittivity on the initial stage of dielectric barrier discharge
Authors: Hrebtov M Yu , Bobrov M S
Published: December 2020

We present a numerical simulation of the simplified ferroelectric plasma source operating in a gas discharge mode. The plasma source contains two electrodes separated by a ferroelectric. High voltage pulse applied to the cathode leads to formation of a dielectric barrier discharge in gas (argon at 1 Torr pressure). The main point of the study is to clarify how the high permittivity of the ferroelectric affects the initial stage of the discharge. Two cases are considered with different values of barrier relative permittivity. The results show that the process of compensation of bound charge affects the electron avalanche formation near the dielectric surface. The electron concentration in the avalanche drops down for materials with higher permittivity.
Evaporation of micro-sized droplets on a heated silicon substrate
Authors: Kunts K A , Kirichenko D P , Bykovskaya E F , Zaitsev D V , Kabov O A
Published: December 2020

The present research is devoted to the evaporation of micro-sized water droplets on a smooth silicon substrate heated from below. The study of this process is relevant for the development of spray cooling systems. Due to the extreme complexity of this phenomenon the mechanism of spray cooling is not fully understood yet. In our experiment the silicon substrate is open to the atmosphere. Evaporation of sessile droplets with the size of the order of 10 μm is studied at the substrate temperature ranging from 23 to 100°C. A shadow method coupled with a high-speed camera is used in the experiment to determine the geometric characteristics of the droplet profile and to calculate the droplet evaporation rate.
Spatial velocity distribution around an endless chain of spherical dust particles
Authors: Salnikov M V , Sukhinin G I
Published: December 2020

This paper presents a numerical model in which selfconsistent distributions of plasma space charge, ion velocity and potential are calculated in a proximity of the infinite chain consisting of spherical dust particles. In the observed model this chain is under an influence of an external electric field. As a result of calculation spatial distributions of ions velocity and plasma potential around the isolated dust particles are obtained. The data obtained reveal that for the electric field of low intercity local maximum in the potential and velocity distribution linearly increases with the rise of the external field strength. However, with further amplification of external electric field the potential maximum starts to decline in contrast to the velocity local maximum.
Caloric properties of Cs60Bi40 alloy in the temperature range of 293-1125 K
Authors: Khairulin A R , Stankus S V
Published: December 2020

The results of the enthalpy measurements of the Cs60Bi40 alloy in the range of 431–1127 K of the solid and liquid states are presented. The experiments were carried out by the mixing method on a massive isoperibolic calorimeter. The estimated errors for enthalpy and heat capacity of the melt were 0.4 and 1.4%, respectively. It was shown that the heat capacity of the melt decreases linearly with increasing temperature, and its absolute value in the studied temperature range is 1.25–1.45 times higher than the additive value. Table of recommended values of caloric properties over the range from 298.15 K to 1175 K was developed.
Heat transfer coefficients of gadolinium in the liquid state
Authors: Samoshkin D A , Agazhanov A Sh , Stankus S V
Published: December 2020

The thermal conductivity and the thermal diffusivity of gadolinium (Gd) have been measured by the laser flash method in the temperature range from 1610 to 1740 K of the liquid state. The measurement error of the heat transfer coefficients was 4–6%. The fitting equations for investigated properties have been received. It has been established, that temperature dependences of transport properties of liquid gadolinium have linear character. The table of reference data for thermal conductivity and thermal diffusivity of gadolinium have been developed for scientific and practical use.
The influence of crucible and crystal rotation on the hydrodynamics of a melt with a Prandtl number 16 and on heat transfer in the Czochralski method
Authors: Berdnikov V S , Vinokurov V V
Published: December 2020

The effect of crucible rotation on the evolution of the melt flow structure at a Prandtl number 16 on the temperature and velocity fields and on convective heat transfer in the Czochralski method is simulated numerically in the mixed convection regimes at a given crystal rotation rate. The ranges of similarity parameters corresponding to stationary and unsteady melt flows and heat transfer regimes, as well as regimes with the most uniform radial distributions of local heat fluxes are determined. In the initial regime Reynolds, Grashof and Marangoni numbers are set to ReK = 95, Gr = 4870 and Ma = 5835.
The study of thermostressed condition of the hydrogen quartz reactor during the methane pyrolysis
Authors: Kudinov I V , Pimenov A A , Mikheeva G V
Published: December 2020

Based on analytical and numerical methods, the detailed studies of the temperature and thermostressed condition of quartz reactor intended for production of hydrogen by pyrolysis of methane passed through the molten tin, are performed. Heating of tin contained in the reactor is realized by the application of electromagnetic field generated by the inductor. The analysis of the study results allows concluding that the values of radial, circular and axial stresses during a uniform movement of the reactor along its height even in the most unfavourable conditions when the temperature drop along the wall of the quartz reactor is maximum and is equal to the difference of temperatures between molten tin and environment (ΔT ≈ 1500 °C) are within the tensile strength limit for quartz σ
p
= 50Mpa (5 kg / mm
2). In case of non-uniform heating of the reactor along its height observed at its partial filling with molten tin, in the area of transfer from the filled part of the reactor to its non-filled part, there are high axial temperature gradients, which result in temperature stresses exceeding the tensile strength limit. By using the obtained results, the recommendations connected with the reactor heating rate and essential for ensuring its safe operation have been developed.
A Fantasy and Magical Adsorbent for Heavy Metal Ions Removal: Melamine
Authors: Guo Jing , Qiu Hongzhi , Wang Caiqiong , Hao Zhihui , Zhang Chenyu , Peng Hao
Published: December 2020

Many kinds of research had been done to treat the wastewater containing heavy metal ions in the world. Adsorption technology had attracted much more attention owing to ease of regeneration, simple operation and high-efficiency. Melamine possessed a great surface area especially modified with organic compounds. It showed efficient adsorption efficiency for various valent metal ions ranged from +1 to +6, which exhibited a bright application future for the treatment of wastewater.
Process simulation of nano-channel forming by thin film deposition
Authors: Jin Jian , Di Si , Hao Wang , Li Xiaojun , Wang Xudi , Sun Xuetong
Published: December 2020

In the traditional fabrication process of micro/nano-fluidic chips, thermal bonding is usually used for channel sealing, but it is easy to cause channel blockage, especially when the channel size is nanometer. The film deposition is a better way to seal the nano channel, and by controlling the deposition angle, the shape and size of the sealed channel can also be controlled. In order to understand the channel formation process of thin film deposition more intuitively, based on the COMSOL software, a free molecular flow module is used to simulate the film deposition process. The growth of the film is characterized by the post-processing of geometric deformation, so as to predict the channel shape. By comparing the simulation results with the experimental results, it can be seen that this simulation can explain the process of forming channels by angle-deposited films to a certain extent, and predict the channel size. In addition, the simulation results, in turn, can guide the film deposition process, so as to control the size of nano channel.
Optimal design of cylindrical sealed cabin based on simulation module
Authors: Zhi Wang , Junxian Yang , Bin Zhao , Xiangtao Ran , Jie Zhao , Wei Zheng
Published: December 2020

For the underwater sealed cabin with cylindrical structure, this paper proposes a theoretical design method based on the critical pressure algorithm of the external pressure cylinder combined with the simulation module embedded in Solidworks. Based on the results of FEA, the cabin structure is continuously optimized, and finally designed an economical and reliable cylindrical cabin structure, which can meet the requirements of LR rules. The design method has guiding significance.
Experimental Investigation of Microchannel Copper Plate Surfaces on Manufacturing and Wettability
Authors: Wu Nini , Zeng Liangcai , Fu Ting , Liu Zhengyang
Published: December 2020

In this study, static contact angle measurement experiments were conducted on smooth copper surface and microchannel structure surfaces under different droplet sizes. The results showed that shallow processing will more easily lead to the deformation of the processed interface. And the wettability of the microchannel surfaces with the same width and different depth were obviously different. Moreover, the contact angles on three microchannel surfaces were almost the same when the size of droplet was 12μl duo to action of gravity. The optimal droplet size is 9μl to measure contact angle in this study.
Finite element analysis of space truss sandwich structure
Authors: Cui Xu , Jin Shan , Zhao Changlin
Published: December 2020

In this paper, three kinds of carbon fiber reinforced epoxy resin (CF / EP) composites, including square, kagome and triangular grid sandwich structures, are analyzed by using ANSYS finite element analysis software. Through the comparison of the analysis results, the surface yield and core failure are the main failure mechanisms in three kinds of three-dimensional finite element models. The average bending loads of square, kagome and triangular grid sandwich structures are 18.0%, 19.7% and 24.6%, respectively. Therefore, the finite element analysis shows that more failures will occur due to the local collapse of the indenter.
Study on magnetic difference of artificial magnetite and natural magnetite
Authors: Wang Linjun , Chen Tiejun , Cui Jinbing , wei Liu
Published: December 2020

The magnetic differences of the artificial magnetite and the natural magnetite were studied to improve the magnetic parameters of artificial magnetite in the study. The effect of roasting conditions on the magnetism of artificial magnetite and the diffidence of magnetism and magnetic behavior of the artificial magnetite and natural magnetite was studied and compared. The results indicate that the magnetically strong artificial magnetite has been obtained under the optimized process parameters of the roasting temperature of 800°C, roasting time of 60min and the mass ratio of pulverized coal to ore (C/O ratio) of 2%. And the magnetic analysis shows that the magnetism of natural magnetite is stronger than that of artificial magnetite under the same conditions, but the remanence and coercivity of artificial magnetite is stronger than natural magnetite. With the decrease of particles, the magnetism of the artificial magnetite changes insignificantly, but the magnetization of natural magnetite decreases gradually; and the difference in the magnetism of two becomes smaller (from 1.53 × 10-4·m3·kg-1 to 0.14 × 10-4m·3·kg-1) with the decrease of particles. The gaps and impurities in the ore are the cause of the difference, which provides a theoretical basis for the further study the size-fractionated magnetic separation of artificial magnetite.
Crack resistance of reinforced-concrete sleepers with elastic rail fastening systems without base-plate
Authors: Plugin A A , Miroshnichenko S V , Lobiak O V , Kalinin OA , Plugin DA
Published: December 2020

The article presents the main results of complex experimental and theoretical research into the crack resistance and the limit state of reinforced-concrete sleepers with elastic rail fastening systems without base-plate. The objective of this study is to uncover reasons for the cracks and other breakages during operation, demonstrate their importance, and produce a set of recommendations for prevention of the most serious defects. The research also involved statistical analysis of the defect factor for sleepers, and determined the number of defects by type according to track layout, traffic density, tonnage transported, concrete grade and other characteristics based on the results of full-scale research of track sections and surveys from maintenance specialists. The full-scale research was made on rail sections under standard operational modes and on a test track section of straight and curved elements with sleepers of concrete grades C32/40, C35/45 and C40/50.The study was based on numerical methods, modelling of the stress-strain behaviour of the track, and estimation of the performance of sleepers with cracks.The method used incremental-iterative algorithms to consider the elastic plastic properties of materials, solve contact problems in operation of rail fastening systems, and also reveal the structural nonlinearity of joint action for track elements. The method was realized in LIRA-SAPR software on the basis of Building Information Modelling (BIM) and the Finite Element Method (FEM).The results were verifiedby experimental research into the sleepers under static and dynamic loads with estimation of crack development in terms of concrete grades, deformation modulus, rigidities of the ballast layer and the sub-grade, position of the reinforcement and other characteristics.
Comparative analysis of the acoustic efficiency of classical and sonic crystal noise barriers
Authors: Gieva Elitsa , Ruskova Ivelina , Nedelchev Krasimir , Kralov Ivan
Published: December 2020

This study presents a comparative analysis of the acoustic efficiency of classical and sonic crystal noise barriers conducted by means of numerical simulation. One of the most common solutions for transport noise reduction is the use of expensive combined noise barriers of high degree of reflection and absorption. Sonic Crystals are a relatively new type of noise barrier under development and investigation. In this study both types of barriers are compared on the basis of their area of application, noise level attenuation behind them, frequency response, technology of manufacturing, maintenance and price. Some of the characteristics are obtained through numerical simulations and experimental data, while others are available in published research studies. On the basis of the results conclusions about the application of sonic crystal noise barriers are made.