bluuebunny/crossref_metadata_2025 huggingface dataset:
PI4P/PS countertransport by ORP10 at ER–endosome membrane contact sites regulates endosome fission
Authors: Kawasaki Asami , Sakai Akiko , Nakanishi Hiroki , Hasegawa Junya , Taguchi Tomohiko , Sasaki Junko , Arai Hiroyuki , Sasaki Takehiko , Igarashi Michihiro , Nakatsu Fubito
Published: November 2021

Membrane contact sites (MCSs) serve as a zone for nonvesicular lipid transport by oxysterol-binding protein (OSBP)-related proteins (ORPs). ORPs mediate lipid countertransport, in which two distinct lipids are transported counterdirectionally. How such lipid countertransport controls specific biological functions, however, remains elusive. We report that lipid countertransport by ORP10 at ER–endosome MCSs regulates retrograde membrane trafficking. ORP10, together with ORP9 and VAP, formed ER–endosome MCSs in a phosphatidylinositol 4-phosphate (PI4P)-dependent manner. ORP10 exhibited a lipid exchange activity toward its ligands, PI4P and phosphatidylserine (PS), between liposomes in vitro, and between the ER and endosomes in situ. Cell biological analysis demonstrated that ORP10 supplies a pool of PS from the ER, in exchange for PI4P, to endosomes where the PS-binding protein EHD1 is recruited to facilitate endosome fission. Our study highlights a novel lipid exchange at ER–endosome MCSs as a nonenzymatic PI4P-to-PS conversion mechanism that organizes membrane remodeling during retrograde membrane trafficking.
Method to evaluate systematic uncertainties due to magnet misalignments in electric dipole moment measurements using a storage ring
Authors: Magiera A , Aggarwal A , Poncza V
Published: November 2021

Various scenarios of measurements of electric dipole moment (EDM) of light hadrons with the use of a storage ring were proposed. Most of these methods are based on the measurement of the vertical spin component for an initially horizontal polarized beam. Since the expected EDM effect is very small, one has to pay attention to various sources of systematic uncertainties. One of the most important sources are misalignments of the magnets forming the storage ring lattice, which may produce an effect that mimics an EDM. This false signal could be much larger than the expected EDM signal, even for very small magnet misalignments. This paper describes a novel method for the determination of the contribution of magnets misalignments to the expected EDM signal. It is shown that the magnitude of this effect could be estimated via a Fourier analysis of the time-dependent vertical polarization. This could be achieved by sampling the vertical polarization with a frequency larger than the beam revolution frequency, which corresponds to polarization measurements in at least two positions in the storage ring. The presented method can be applied to any scenario proposed for EDM measurements using a storage ring.
The METREPOL criteria—are they still relevant?
Authors: Lebaron-Jacobs Laurence , Herrera-Reyes Eduardo
Published: November 2021

The medical management of radiation accidents manual on the acute radiation syndrome proposed a successful strategic approach to diagnosing and treating acute radiation syndrome: the response category concept. Based on clinical and laboratory parameters, this approach aimed to assess damage to critical organ systems as a function of time, categorising different therapeutical approaches. After 20 years of its publication, the following paper attempts to provide a broad overview of this important document and tries to respond if proposed criteria are still relevant for the medical management of radiation-induced injuries. In addition, a critical analysis of its limitations and perspectives is proposed.
A coherent framework for non-ionising radiation protection
Authors: Tinker Rick , Abramowicz Jacques , Karabetsos Efthymios , Magnusson Sigurður , Matthes Rüdiger , Moser Mirjana , Niu Shengli , O’Hagan John , van Deventer Emilie
Published: November 2021

A coherent and overarching framework for health protection from non-ionising radiation (NIR) does not currently exist. Instead, many governments maintain different compliance needs targeting only some NIR exposure situations. An international framework developed by the World Health Organization would promote a globally consistent approach for the protection of people from NIR. Designed based on decades of practical experience the framework provides guidance on establishing clear national health and safety objectives and how they should be achieved. It supports multisectoral action and engagement by providing a common language and systematic approach for managing NIR. The framework should allow governments to respond to policy challenges on how to achieve effective protection of people, especially in a world that is rapidly deploying new NIR technologies. In this paper the concepts and key features are presented that underpin the framework for NIR protection, including examples of implementation.
Skin dose contamination conversion coefficients. Benchmark with three simulation codes
Authors: Frosio Thomas , Bertreix Philippe , Menaa Nabil , Thomas Samuel , EBERHARDT Holger , ENDRES Janis
Published: November 2021

Handling of radioactive material by operators can lead to contamination at the surface of the skin in case of an accident. The quantification of the dose received by the skin due to a contamination scenario is performed by means of dedicated dose coefficients as it is the case for other radiation protection dose quantities described in the literature. However, most available coefficients do not match realistic scenarios according to state-of-the-art of science and technology. Therefore, this work deals with dedicated dose conversion factors for skin contamination. Since there is an increasing demand on dose coefficients in general, these specific coefficients can be used for various calculations in radiation protection. In this work a method to evaluate such coefficients for the skin contamination dose related to photons, electrons, positrons, alpha and neutron particles is proposed. The coefficients are generated using Monte-Carlo simulations with three well established calculation codes (FLUKA, MCNP, and GEANT4). The results of the various codes are compared against each other for benchmarking purposes. The new dose coefficients allow the computation of the skin received dose, in the case of skin contamination scenario of an individual, taking into account the decay radiation of the radionuclides of interest. To benchmark the quantity derived here, comparisons of radionuclide contamination doses to the skin using the VARSKIN code available in the literature are performed with the results of this work.
Reanalysis of cancer mortality using reconstructed organ-absorbed dose: J-EPISODE 1991‒2010
Authors: Furuta Hiroshige , Kudo Shin’ichi , Ishizawa Noboru , Saigusa Shin
Published: November 2021

The Japanese Epidemiological Study on Low-Dose Radiation Effects (J-EPISODE) has been conducted since 1990 by the Radiation Effects Association to analyse health effects for nuclear workers. It uses the recorded doses, i.e. dosimeter readings, evaluated in H
p(10) for estimation of radiation risk; however, the International Commission on Radiological Protection does not recommend the use of effective doses for epidemiological evaluation and instead recommends the use of organ-absorbed doses for assessing cancer risk. Recently, the J-EPISODE has developed a conversion factor that can convert dosimeter readings to organ-absorbed doses following, in principle, the approach adopted by the International Agency for Research on Cancer 15-Country Collaborative Study. The approach was modified based on recent dosimeter usage practices and the Japanese physique. The aim of this study was to reanalyse the excess relative risk (ERR) of cancer mortality for the J-EPISODE using the previous analysis method but substituting the organ-absorbed dose for the recorded dose to confirm the adaptability and relevance of organ-absorbed doses for the J-EPISODE. The organ-absorbed doses from 1957 to 2010 were reconstructed for the whole cohort. The cancer mortality risk was reanalysed with Poisson regression methods, first by comparing the ERR/Gy for all cancers excluding leukaemia with the risk after excluding lung cancer for the whole cohort of 204 103 participants. In the whole cohort, all cancers excluding leukaemia, lung cancer and non-Hodgkin’s lymphoma had statistically significant positive ERR/Gy estimates; leukaemia excluding chronic lymphocytic leukaemia had negative but not statistically significant estimates. Gallbladder cancer and pancreatic cancer showed statistically significant negative. Then, a subcohort of 71 733 respondents was selected based on lifestyle surveys with data on qualitative smoking status as well as quantitative smoking information on pack-years. Pack-years for current smokers and former smokers and years since the cessation of smoking for former smokers were used for the smoking-adjusted model. The most important feature of the J-EPISODE revealed to date was a decreasing tendency of the ERR/Sv by the smoking adjustment. For almost all causes of death such as lung cancer and stomach cancer, the estimated ERR/Gy decreased by the smoking adjustment, although those for the colon, prostate and kidney and other urinary organs were almost the same after the adjustment. This tendency remained unchanged even when using the organ-absorbed dose, indicating the appropriateness of using organ-absorbed doses for further risk analysis. At the same time, it indicated that confounding by smoking seriously biased the radiation risk estimates in the J-EPISODE and thus should be accounted even if organ dose is used.
Absolute efficiency of a two-stage microchannel plate for electrons in the 30–900 eV energy range
Authors: Apponi A , Pandolfi F , Rago I , Cavoto G , Mariani C , Ruocco A
Published: November 2021

We report on an apparatus able to measure the absolute detection efficiency of a detector for electrons in the 30–900 eV range. In particular, we discuss the characterisation of a two-stage chevron microchannel plate (MCP). The measurements have been performed in the LASEC laboratory at Roma Tre University, whit a custom-made electron gun. The very good stability of the beam current in the fA range, together with the picoammeter nominal resolution of 0.01 fA, allowed the measurement of the MCP absolute efficiency ε. We found an

ϵ
=
(
0.489
±
0.003
)

with no evident energy dependence. We fully characterised the MCP pulse shape distribution, which is quasi-Gaussian with a well visible peak above the noise level. We measured a 68

%

variation of the average pulse height between 30 and 500 eV. Furthermore, with a deeper analysis of the pulse shape, and in particular of the correlation between pulse height, area and width, we found a method to discriminate single- and multi- electron events occurring within a 10 ns time window.
Predicting distant metastases in soft-tissue sarcomas from PET-CT scans using constrained hierarchical multi-modality feature learning
Authors: Peng Yige , Bi Lei , Kumar Ashnil , Fulham Michael , Feng Dagan , Kim Jinman
Published: November 2021

Objective. Positron emission tomography-computed tomography (PET-CT) is regarded as the imaging modality of choice for the management of soft-tissue sarcomas (STSs). Distant metastases (DM) are the leading cause of death in STS patients and early detection is important to effectively manage tumors with surgery, radiotherapy and chemotherapy. In this study, we aim to early detect DM in patients with STS using their PET-CT data. Approach. We derive a new convolutional neural network method for early DM detection. The novelty of our method is the introduction of a constrained hierarchical multi-modality feature learning approach to integrate functional imaging (PET) features with anatomical imaging (CT) features. In addition, we removed the reliance on manual input, e.g. tumor delineation, for extracting imaging features. Main results. Our experimental results on a well-established benchmark PET-CT dataset show that our method achieved the highest accuracy (0.896) and AUC (0.903) scores when compared to the state-of-the-art methods (unpaired student’s t-test p-value < 0.05). Significance. Our method could be an effective and supportive tool to aid physicians in tumor quantification and in identifying image biomarkers for cancer treatment.
Resonant wave–filament interactions as a loss mechanism for HHFW heating and current drive
Authors: Tierens W , Myra J R , Bilato R , Colas L
Published: November 2021

Perkins et al (2012 Phys. Rev. Lett.
109 045001) reported unexpected power losses during high harmonic fast wave (HHFW) heating and current drive in the National Spherical Torus Experiment (NSTX). Recently, Tierens et al (2020 Phys. Plasmas
27 010702) proposed that these losses may be attributable to surface waves on field-aligned plasma filaments, which carry power along the filaments, to be lost at the endpoints where the filaments intersect the limiters. In this work, we show that there is indeed a resonant loss mechanism associated with the excitation of these surface waves, and derive an analytic expression for the power lost to surface wave modes at each filament.
Experiments on the dynamic wetting of growing icicles
Authors: Ladan John , Morris Stephen W
Published: November 2021

The distinctive shape of an icicle is the outcome of a highly non-equilibrium process involving heat and mass transport in the presence of fluid flowing over an evolving topography. It has previously been shown that the ripple patterns with a near universal wavelength that are observed on many icicles are correlated with small levels of impurities in the feed water. Models of icicle shape evolution, and of the origin of the ripple pattern, require a detailed understanding of how liquid water flows over a growing icicle. The impurity effect is not accounted for by any existing model of ripple formation. Here, we explore this flow dynamics using laboratory-grown icicles with a fluorescent dye as an impurity. Contrary to previous models, we find that the ice is incompletely wetted by the liquid phase, and that the whole process is much more stochastic than has been previously assumed. In addition, the presence of impurities modifies the wetting properties of the ice surface, while the emerging topography interacts with the liquid distribution. There is evidence for mixed-phase ice. These observations must inform any successful model of an impurity-driven rippling instability. Our results have general implications for the morphological evolution of many natural, gravity-driven, wet ice growth processes.
Antiferromagnetic topological crystalline insulator and mixed Weyl semimetal in two-dimensional NpAs monolayer
Authors: Zou Xiaorong , Mao Ning , Li Bingyang , Sun Wenli , Huang Baibiao , Dai Ying , Niu Chengwang
Published: November 2021

Magnetic topological states have attracted significant attentions due to their intriguing quantum phenomena and potential applications in topological spintronic devices. Here, we propose a two-dimensional material NpAs monolayer as a candidate for multiple topological states accompanied with the changes of magnetic structures. Under the antiferromagnetic configuration, the long-awaited topological crystalline insulator (TCI) emerges with a nonzero mirror Chern number

C

M

=
1

and a giant band gap of 630 meV, and remarkably a pair of gapless edge states can be tailored by rotating the magnetization directions while the TCI phase survives. Moreover, we establish the existence of quantum anomalous Hall effect and nontrivial nodal points under the ferromagnetic configuration, thereby giving rise to the mixed Weyl semimetal after adding the magnetization direction to topological classification. Our findings not only provide an ideal candidate for uncovering exotic topological characters with magnetism but also put forward potential applications in topological spintronics.
Confidence polytopes for quantum process tomography
Authors: Kiktenko E O , Norkin D O , Fedorov A K
Published: November 2021

In the present work, we propose a generalization of the confidence polytopes approach for quantum state tomography (QST) to the case of quantum process tomography (QPT). Our approach allows obtaining a confidence region in the polytope form for a Choi matrix of an unknown quantum channel based on the measurement results of the corresponding QPT experiment. The method uses the improved version of the expression for confidence levels for the case of several positive operator-valued measures. We then demonstrate how confidence polytopes can be employed for calculating confidence intervals for affine functions of quantum states (Choi matrices), such as fidelities and observables mean values, which are used both in QST and QPT settings. As we propose, this problem can be efficiently solved using linear programming tools. We also study the performance and scalability of the developed approach on the basis of simulation and experimental data collected using IBM cloud quantum processor.
Double shear layer evolution on the non-uniform computational mesh
Authors: Kulikov Yu M , Son E E
Published: November 2021

This paper considers the problem of a thin shear layer evolution at Reynolds number rmRe = 400000 using the novel Compact Accurately Boundary Adjusting high-Resolution Technique (CABARET). The study is focused on the effect of the specific mesh refinement in the high shear rate areas on the flow properties under the influence of the developing instability. The original sequence of computational meshes (2562, 5122, 10242, 20482 cells) is modified using an iterative refinement algorithm based on the hyperbolic tangent. The properties of the solutions obtained are discussed in terms of the initial momentum thickness and the initial vorticity thickness, viscous and dilatational dissipation rates and also integral enstrophy. The growth rate for the most unstable mode depending on the mesh resolution is considered. In conclusion the accuracy of calculated mesh functions is estimated via L
1, L
2, L
∞ norms.
Advances in thermoelectric (GeTe)
x
(AgSbTe2)100 – x
Authors: Liu Hongxia , Zhang Xinyue , Li Wen , Pei Yanzhong
Published: November 2021

The (GeTe)
x
(AgSbTe2)100 – x
alloys, also called TAGS-x in short, have long been demonstrated as a promising candidate for thermoelectric applications with successful services as the p-type leg in radioisotope thermoelectric generators for space missions. This largely stems from the complex band structure for a superior electronic performance and strong anharmonicity for a low lattice thermal conductivity. Utilization of the proven strategies including carrier concentration optimization, band and defects engineering, an extraordinary thermoelectric figure of merit, zT, has been achieved in TAGS-based alloys. Here, crystal structure, band structure, microstructure, synthesis techniques and thermoelectric transport properties of TAGS-based alloys, as well as successful strategies for manipulating the thermoelectric performance, are surveyed with opportunities for further advancements. These strategies involved are believed to be in principle applicable for advancing many other thermoelectrics.
Explosive synchronization: From synthetic to real-world networks
Authors: Bayani Atiyeh , Jafari Sajad , Azarnoush Hamed
Published: November 2021

Synchronization is a widespread phenomenon in both synthetic and real-world networks. This collective behavior of simple and complex systems has been attracting much research during the last decades. Two different routes to synchrony are defined in networks; first-order, characterized as explosive, and second-order, characterized as continuous transition. Although pioneer researches explained that the transition type is a generic feature in the networks, recent studies proposed some frameworks in which different phase and even chaotic oscillators exhibit explosive synchronization. The relationship between the structural properties of the network and the dynamical features of the oscillators is mainly proclaimed because some of these frameworks show abrupt transitions. Despite different theoretical analyses about the appearance of the first-order transition, studies are limited to the mean-field theory, which cannot be generalized to all networks. There are different real-world and man-made networks whose properties can be characterized in terms of explosive synchronization,e.g., the transition from unconsciousness to wakefulness in the brain and spontaneous synchronization of power-grid networks. In this review article, explosive synchronization is discussed from two main aspects. First, pioneer articles are categorized from the dynamical-structural framework point of view. Then, articles that considered different oscillators in the explosive synchronization frameworks are studied. In this article, the main focus is on the explosive synchronization in networks with chaotic and neuronal oscillators. Also, efforts have been made to consider the recent articles which proposed new frameworks of explosive synchronization.
Validation of low-Z impurity transport theory using boron perturbation experiments at ASDEX upgrade
Authors: McDermott R.M. , Angioni C. , Cavedon M. , Kappatou A. , Dux R. , Fischer R. , Manas P. , the ASDEX Upgrade Team
Published: November 2021

An experimental technique has been developed at ASDEX upgrade (AUG) to separately identify the diffusive and convective components of the boron particle flux. Using this technique a database of B transport coefficients has been assembled that shows that the normalized ion temperature gradient (

R
/

L

T

i

) is the strongest organizing parameter for both the B diffusion and convection and large

R
/

L

T

i

is a necessary ingredient to obtain hollow B density profiles in AUG. This database also shows that large changes in the applied neutral beam injection (NBI) have a relatively small impact on impurity transport compared to similar changes in electron cyclotron resonance heating (ECRH). Even low levels of ECRH power dramatically increase both the diffusive and convective fluxes and lead to peaking of the impurity density profile. Comparisons to a combination of neoclassical and quasi-linear gyrokinetic simulations show good agreement in the measured and predicted diffusion coefficients. The outward convection measured in NBI dominated plasmas, however, is not well captured by the simulations, despite the inclusion of fast ions. In contrast, the convection is reasonably well reproduced for plasmas with flat or peaked boron density profiles. This dataset provides an excellent experimental validation of the non-monotonic, predicted, convective-particle-flux created by the combination of pure-pinch, thermo-diffusion, and roto-diffusion. In addition, this dataset demonstrates a non-monotonic dependence of the experimental particle diffusivity to ion heat conductivity (D/χ
i) in qualitative agreement with theoretical predictions.
Eddy resolving simulation of mixed convection in a rotating annular cavity with one heated disk and axial throughflow: the effect of the surface macro-relief
Authors: Abramov A G , Zaitsev D K , Smirnov E M , Kitanina E E
Published: November 2021

We present the results of hybrid RANS/LES computations of non-isothermal buoyant flow in a rapidly revolving enclosure with paraxial transit stream of the cooling air. Foil heat flux meters mounted on the disk surface in the base experiment are mimicked by means of the grid resolved macro-relief. The results obtained using the relief and smooth disk models are collated with available measurements. According to the simulation, the addition of the relief has resulted in switching from two to three pairs of cyclonic/anti-cyclonic global circulations, and the overall heat transfer rate has increased by 20%. It has been found also that the sensor readings can be up to 25% higher than the heat flux averaged over the circumference at the same radius. Despite this distinct effect of the surface relief, the local heat transfer rate is still underestimated considerably as compared to measurements.
Conjugate heat transfer numerical study of the ejector by means of SU2 solver
Authors: Brezgin D V , Aronson K E , Mazzelli F , Milazzo A
Published: November 2021

In this paper, the test supersonic ejector with conjugate heat transfer in solid bodies has been studied numerically. An extensive numerical campaign by means of open-source SU2 solver is performed to analyze the fluid dynamics of the ejector flowfield accounting for the heat conduction in solids. The fluid domain simulation is carried out by employing compressible RANS treatment whilst the heat distribution in solids is predicted by simultaneous solving the steady heat conduction equation. The working fluid is R245fa and all simulations are performed accounting for real gas properties of the refrigerant. Experimental data against numerical results comparison showed close agreement both in terms mass flow rates and static pressure distribution along the walls. Within the CFD trials, the most valuable flow parameters at a wall vicinity are compared: distribution across the boundary layer of the temperature and the turbulent kinetic energy specific dissipation rate, boundary layer displacement and momentum thicknesses. A comprehensive analysis of the simulation results cases with adiabatic walls against cases with heat permeable walls revealed the actual differences of the flow properties in the wall vicinity. However, the ejector performance has not changed noticeably while accounting for the heat conduction in solids.
Enhancement of heat transfer at boiling in electrohydrodynamic flow
Authors: Chernica I M , Bologa M K , Motorin O V , Kozhevnikov I V
Published: November 2021

The influence of the electric field strength and interelectrode spacing on the heat transfer intensity at boiling in an electrohydrodynamic flow was studied. It was stated that the heat transfer coefficient increases with the increasing of the field strength. The influence of the interelectrode spacing is ambiguous. The efficiency of the action of a electrohydrodynamic flow on the heat transfer intensity at boiling was evaluated using the ratio of the heat transfer coefficient at boiling in the field to the heat transfer coefficient at boiling without the field. The relationships for calculation were obtained that satisfactorily agree with the experimental data.
Anomalous intensification of separated flow and heat transfer in one and multiple row deep inclined oval trench dimples on the wall of a narrow channel and on the plate
Authors: Isaev S A , Leontiev A I , Son E E , Guvernyuk S V , Zubin M A , Mikheev N I , Popov I A , Nikushchenko D V , Sudakov A G
Published: November 2021

At the stands of Research Institute of Mechanics at the Moscow State University, we experimentally confirmed the mechanism of anomalous intensification of the separation flow and heat exchange in inclined oval-trench dimples (OTD) on the plate, which was discovered during numerical studies. The measured static pressure differences in single OTD at Re=6.7×104 are in good agreement with the numerical forecasts within the framework of the RANS approach at Re=104.
Liquefied natural gas (LNG) and DC electric power transfer system by cryogenic pipe of superconducting DC power transmission (SCDC)
Authors: Yamaguchi Sataro , Ivanov Yury , Sugiyama Linda
Published: November 2021

We propose a hybrid energy transmission pipeline that combines the liquefied natural gas (LNG) cryogenic pipelines and superconducting direct current (DC) electrical power transmission cable system (SCDC). The system design is based on experimental data from the SCDC Ishikari project in Japan and related laboratory experiments. The particular structure of the hybrid cryogenic pipe connects the thermal radiation shield of the pipe that contains the DC high temperature superconducting (HTS) electrical cable to the LNG pipe and significantly reduces the heat leak into the SCDC pipe. Because the specific heat of LNG is higher than that of liquid nitrogen and the LNG transfer rate is quite high, the thermal loss of the SCDC cable becomes only 1/100 that of present-day conventional copper cables, far below the factor 1/10 reduction achievable by a stand-alone SCDC transmission lines. The LNG temperature rises by less than 2 K over a 100 km transport distance, which is negligible in actual use. LNG also saves significantly on pumping power compared to a natural gas pipeline. To liquefy the LNG at cryogenic temperature from natural gas at ambient temperature requires a large refrigerator that consumes enormous power. The gas pipeline, however, needs a compressor to produce high-pressure gas, which also consumes a massive amount of power. Due to these considerations, the proposed hybrid system is a viable design for the long-distance joint transportation of LNG and electricity.
Intensification of heat transfer in the inlet of the convective stage of the recuperative-burner unit
Authors: Leukhin Yu L , Alekseev P D
Published: November 2021

The study of aerodynamics and heat transfer in the recuperator convective stage of the recuperative-burner unit with the jet leakage of the flue gas flow onto the outer cylindrical surface is carried out. Numerical modeling of the problem was carried out in a three-dimensional formulation using the ANSYS Fluent software package. It was found that in the original design of the recuperative-burner unit, there is a significant unevenness of heat transfer along the length and perimeter of the working surface of the convective stage. In the initial section of the annular gap, a stagnant zone with the lowest heat transfer rate is observed. To eliminate the stagnant zone and to intensify heat transfer on the surface in this area, it is proposed to make the entrance to the perforated pipe in the form of an inner quarter of a torus; to install smooth protrusions on its surface; to locate an annular flow divider on the inner surface of the heat transfer wall, which separates the front part of the annular channel with formation of a set of vortex chambers. The research results are presented.
Measurement of velocity in swirling flows of liquid metals in the presence of a magnetic field
Authors: Listratov Ya I , Kolesnikov Yu B , Belyaev I A , Sviridov E V , Krasnov D , Zikanov O
Published: November 2021

Studies of the dynamics of a round submerged jet of liquid metal in a transverse magnetic field. The experiments were performed in the range of Reynolds numbers up to 1000 and Hartmann numbers up to 1300 using a probe technique for measuring velocity using potential sensors. Detailed three-dimensional flow structures are visualized using a direct numerical simulation method independent of the experiment. The paper presents data on the averaged velocity field and statistical characteristics of the flow, reproducing the complex nature of a substantially unsteady flow, in which zones of reverse fluid flows are detected and a significant heterogeneity of the velocity field is observed.
Evaluation of melt-water premixture formation due to Rayleigh-Taylor instabilities
Authors: Melikhov V I , Melikhov O I , Finoshkina D V
Published: November 2021

A linear analysis of the stability of the three-layer stratified hydrodynamic system “water (top) – steam – melt (bottom)” has been performed. Kinematic and dynamic conditions on the “water – steam” and “steam – melt” interfaces are formulated, and on their basis a dispersion equation is obtained that relates the circular frequency of perturbations to the wavenumber. Analysis of this equation made it possible to determine the region of instability of this system and to find the wavenumber of the most fastly growing harmonics. The results obtained were used to estimate the size of bubbles formed at the interface between steam and water due to the development of the Rayleigh-Taylor instability. The obtained theoretical results are consistent with experimental observations in such systems. The heights of the melt splashes into water due to the collapse of the formed steam bubble were estimated. The obtained estimations demonstrate possibilities of the formation of melt-water mixture region during the spreading of the melt under a water layer, in which a strong steam explosion can occur.
Investigation of the direct-flow jets vortex motion in the M-shaped boiler invert furnace
Authors: Prokhorov V B , Kirichkov V S , Chernov S L , Kaverin A A , Fomenko N E
Published: November 2021

For advanced ultra-supercritical parameters (A-USC) of steam, the design of an M-shaped boiler is proposed, designed to operate in a 500 MW unit on a lean coal (grade TR). The boiler profile is selected from the condition of minimizing the length of the main steamlines made of expensive nickel-alloy steel. With regard to this boiler, a scheme has been developed for pulverized coal combustion in an invert furnace using direct-flow burners and nozzles. Research has been carried out on the physical model of the furnace in the implementation of this combustion scheme: a qualitative study of the trajectories of the burner jets, jets of secondary and tertiary air obtained by their hot spark visualization; quantitative determination of the main characteristics of burner jets and their weight gain. The studies have shown the high efficiency of the recommended scheme of the furnace-burner device: a staged supply of the oxidizer along the flame length and along the furnace height is organized; the dynamic pressure of jets on the furnace wall tubes is excluded; vortex furnace aerodynamics should provide a high degree of burnout of coal dust particles; air jets evenly fill the horizontal section of the furnace; the ejection capacity of turbulent jets is much higher than for a flat submerged jet.
Development and verification of methods for predicting the frequency of self-oscillations in swirling coolant flows of nuclear power plants
Authors: Proskuryakov KN , Anikeev AV
Published: November 2021

Methods and algorithms for calculating the frequency of self-oscillations in swirling coolant flows of nuclear power plants with VVER reactors have been developed. The frequency of self-oscillations occurring in the acoustic sections of the primary circuit and their connections in the starting modes of the power unit and when operating at the rated power level is predicted. It is established that the self-oscillation frequencies can fall into the frequency bandwidth of mechanical vibrations and vibrations of the reactor plant’s internal devices. It is shown that in order to prevent the resonance of self-oscillations of the coolant with the vibration frequencies of internal devices, it is necessary and sufficient to take the frequency of self-oscillations outside the bandwidth of the vibration frequency of structures. The results of verification of the results of forecasting the frequency of self-oscillations in swirling coolant flows at a nuclear power plant unit with VVER are presented. The application of the developed technique shows that the pendulum oscillations of the VVER - 1200 body are caused by an increase in the parameters of the coolant and the geometric dimensions of the VVER - 1200 reactor compared to VVER-1000.
Numerical simulation of the branching blood flow in a model of the femoral artery-graft junction
Authors: Sherstneva M A , Smirnov E M , Yukhnev A D , Vrabiy A A
Published: November 2021

Annotation

The results of numerical simulation of pulsating blood flow in a three-dimensional model of the femoral artery-graft junction are presented. The study is focused on the influence of the flow rates ratio in two branches of the branching flow on the location and size of the recirculation flow areas in the shunt and in the common femoral artery, with an emphasis on the analysis of the anastomotic zone. Areas with small values of the cycle-averaged shear stresses and increased values of the shear stress oscillation index, potentially dangerous from the point of view of the neointima growth in the shunt, are identified.
Thermal physical processes during forming of biocompatible Ca-P coatings by detonation spraying
Authors: Skriabin A S , Shakurov A V , Vesnin V R , Tsygankov P A
Published: November 2021

Carbon-carbon composites with calcium phosphate (Ca-P) coatings (with a thickness up to of ≈100 μm) are considering as prospective grafts for defect bone substitution. Detonation spraying of Ca-P layers allows to fulfil a deposition mode with relative low temperature loads (up to a temperature of the processed surface of ≈850…1100 K) under a pulsed pressure of ≈2…6 bar. Such deposition conditions could promote to minimal thermal decomposition of feedstock HAp.
Investigation of the saturated steam sampling method influence on the sample representativeness in chemical control systems at thermal power plants
Authors: Yegoshina O V , Zvonareva S K
Published: November 2021

The most important requirement for sampling is the sample representativeness, which is achieved by the design and location choice of sample nozzle, as well as the speed mode and the presence of sharp pressure drops in the saturated steam flow. The Ansys CFX software package simulates the sampling processes saturated steam in power units with low, medium and high pressure boilers which are used on operating thermal power plants. The saturated steam was sampled from low-pressure boiler by a single-strip probe with a Venturi nozzle, from the medium-pressure boiler was sampled by tapping a pipe at 90 to the main steam line, and the steam of the high – pressure boiler was sampled by a wellhead probe. In three sampling cases it is found that of saturated steam, the flow in the sample nozzle loses speed and decreases to values unacceptable for the selection of a representative sample-below tear rate of the moisture film from the surface. It is confirmed that in the industrial sampling conditions, the condition of speeds equality in the main steam line and in the sample nozzle is not met, which leads to a violation of the sample representativeness. The paper studies the change in the composition of the sampled saturated vapor sample after the film formation on the sample’s nozzle wall in relation to power units with ammonia dosing. It was found that the sample received by the chemical control analyzers is depleted due to the formation of a film and the ferrum and ammonia concentration in moisture droplets on the inner surface of the sampling line.
Development of the design of the research module - model of a high-temperature surface with induction heating
Authors: Varava A N , Demidov A S , Zakharenkov A V , Loktionov V D , Komov A T , Dedov A V
Published: November 2021

The paper describes a test bench for evaluating the cooling efficiency of a working area with a high energy density using a two-component dispersed coolant flow. The design of a pneumatic sprayer and the scheme of the working area cooled by a two-component dispersed flow are described. A description of the design of the new research module and a scheme for installing thermocouples on it is given. A method for measuring the temperature of the walls of the research module is proposed. Adjustment tests were performed at the operating parameters of the coolant p
water = 2,5·105 Pa, p
air = 2,0·105 Pa, G
water = 0,048 kg/c; G
air = 1,7·10−3 kg/c.
Features of metastable superheated water atomization when being discharged through convergent-divergent nozzles at different superheat values
Authors: Zalkind V I , Nizovskiy V L , Nizovskiy LV , Schigel S S
Published: November 2021

Experiments with the metastable superheated water atomization proved the significant increase of the submicron droplets mass fraction at the outlet of convergent-divergent nozzle from 0.45-0.55 to 0.75-0.9 with an increase of the inlet water temperature from170to255°C. Two different approaches to dimensionless treatment of the atomization processdata and determining the boundary of the zone of flashing predominance are compared. The analysis of two approaches to dimensionless treatment of experimental and calculating results concerning transition to predominating role of nucleation in the process of superheated liquid atomization in convergent-divergent nozzles is done.
Automated Solving Algorithm and Application for Oriented Bounding Box Based on Principal Axis of Inertia
Authors: Zhang Wenguo , Zhang Le , Lei Pei , Jin Xiaobo
Published: November 2021

In mechanical design and manufacture, the minimum size of raw material of each part should be measured before processing. Generally, this size could be equal to the size of minimum bounding box. When the assembled parts of a product reach an enormous quantity, the measurement would be a rough work. This paper introduced an automated solving algorithm for the oriented bounding box based on principal axis of inertia, combined with CATIA structural tree recursive traversal algorithm according to CAA V5 Automation API, to implement an automated solution of the engineering acceptable minimum oriented bounding box of CATIA model.
Minimum Disturbance Attitude Control Algorithm for DFFSR
Authors: Li Huazhong , Zhou Yanbing
Published: November 2021

Aiming at the attitude disturbance problem of Dual-arm Free Flying Space Robot(DFFSR), firstly, the kinematics equation of DFFSR has been established by using the geometric relationship of each link of DFFSR, the characteristic equation of manipulator, and the linear momentum and angular momentum conservation law of the system in microgravity environment; Secondly, based on the established Generalized Jacobian Matrix(GJM) describing the relationship between the end-effector motion velocity of DFFSR manipulator and the motion velocity of each joint, the relationship between the motion velocity of each joint of DFFSR manipulator and the angular velocity of satellite base has been derived, and the attitude interference model of DFFSR has been established; Finally, the Minimum Attitude Disturbance Map(MADM) algorithm for calculating the DFFSR manipulator has been established, and the attitude control algorithm based on MADM has been proposed. The attitude control method can ensure that the attitude of the satellite base of DFFSR remains unchanged during the movement of the manipulator.
Application of Controllable Splitting Grouting Technology in Loess Foundation Reinforcement
Authors: Liu Qingang , Zhou Mingru , Zhong Lin , Li Shaofei , Chen Yiming
Published: November 2021

Taking the foundation settlement accident of a large heating boiler foundation in a city in collapsible loess area as an example, controllable splitting grouting can be achieved by controlling the grouting pressure, grouting pipe opening form, grouting volume and grouting method etc., so as to stabilize foundation settlement and improve foundation bearing capacity, for the boiler with large uneven settlement, for boilers with large uneven settlement, quicklime piles are used to jack up the foundation after splitting grouting to stabilize the foundation, the foundation is lifted with quicklime piles after splitting grouting to stabilize the foundation. The results show that the grouting amount of soil is within the design range, the grout splits in the soil several times to form a slurry vein, the settlement is stable after boiler reinforcement, the quicklime method can jack up the foundation and reduce the uneven settlement of the foundation, and the use of controllable splitting grouting can basically eliminate the slight collapsibility grade loess, which provides a new idea for solving the similar problem of uneven settlement of collapsible loess foundation buildings.
Effect of Shell Temperature on Thermal Resistance and Junction Temperature for Power Diode
Authors: Chen Fan , Chen Long , Lian Pengfei , Liu Dapeng , Tao Shuai , Kong Zebin
Published: November 2021

Accurate measurement of junction temperature can avoid thermal failure of diode. During aging test, junction temperature should be indirectly calculated by testing its thermal resistance. In this paper, junction-to-case thermal resistance (Rthjc) of XX diode is tested by T3ster based on transient dual interface method. Its Rthjc is about 1.23K/W at 25°C and contains PN junction thermal resistance, metal shell thermal resistance and Sn-based solder thermal resistance, respectively. These three types of thermal resistance decrease in order. Effect of shell temperature on junction temperature and Rthjc is then discussed. As shell temperature increases, temperature variation of PN junction before and after heating and corresponding thermal resistance Rthjc both increase.
Carburized Layer Cracking Analysis of Counterweight Blocks of Speed Controller
Authors: Jiang Tao , Zhang Bing , Mao Yimeng , Cheng Jiale , Shi Xiaodong
Published: November 2021

Trace and fracture analysis, metallographic examination, residual stress testing, and material analysis were carried out, coupled with examining the failure timeline, to analyze the cracking problem of 12CrNi3A steel counterweight blocks under multi-factor coupling. The results show that the cracks of the counterweight blocks are intergranular microcracks in the carburized layer and they are delayed cracks under the joint action of microstructure stress, grinding stress and hydrogen. The delayed cracking of the counterweight blocks is mainly related to abnormal hydrogen absorption during surface treatment and poor grinding quality. The obvious microstructure segregation in raw material and the thicker carburized layer promoted the cracking. The following measures should be comprehensively taken to prevent such failure: strictly controlling raw material quality, hydrogen absorption and stress, as well as increasing the processes to remove hydrogen, reduce stress and stabilize microstructure.
Theoretical and Numerical Analysis of the Fatigue Strength of Mechanical Material and Part under Uniaxial Stress
Authors: Yang Ze , Yang Yiyong , Li Jianyong , Ji Linhong , Cheng Jia
Published: November 2021

To characterize the fatigue strength of mechanical material and part, a methodology combining the fatigue damage theory with the numerical simulation is proposed under three types of uniaxial loads. The equal-life fatigue curve of a shaft is used for the theoretical and numerical analysis of fatigue damage. Its theoretical fatigue strengths under different loadings are gained through theory equations. Utilizing the mean stress correction method, the stress distribution and fatigue life of the shaft are obtained through the collaborative simulation of ANSYS and nCode software. Consequently, the resultant fatigue lives are all within the value band of basic cycle number as demanded in practice, implying the correction and validation of theory analysis. The proposed strategy provides a new pathway and perspective for the analysis of fatigue damage.
The Effect of Polymerization Temperature on the Properties of Polyvinyl Fluoride Polymerization in Supercritical Carbon Dioxide
Authors: Liu Wei , Zhang Yanzhong , Chang Huaiyun , Cai Rong , Ma Peiliang
Published: November 2021

The ongoing search for environmentally friendlier alternative to the organic solvents used in chemical processes has led to the development of technologies based on supercritical carbon dioxide (scCO2), which is non-flammable, non-toxic and relatively inert fluid. Polymer chemistry does not escape this trend. Fluoropolymers prepared in scCO2 have many special properties, which are different from fluoropolymers that use water as the reaction medium, this paper studies the effect of polymerization temperature on polyvinyl fluoride polymerization in supercritical carbon dioxide. The results show that as the polymerization temperature increases, the intrinsic viscosity and shear viscosity of the polymer gradually decreases; at the same time, the increasing of polymerization temperature leads to higher proportion of irregular structure of the polymer, which causes lower melting point and lower crystallinity, and the film prepared by the resin also exhibits a higher visible light transmittance. The above results show that the resin polymerized in supercritical carbon dioxide can impart better performance to conventional polymerization, which expands the potential application fields of the resin.