bluuebunny/crossref_metadata_2025 huggingface dataset:
The main problems of transmutation of actinides and long-lived fission products from NPP spent fuel
Authors: Tikhomirov G V , Gerasimov A S
Published: December 2020

The paper formulates the main problems associated with research on transmutation, which should be paid attention to by today’s young researchers. The processes of production of hazardous nuclides during transmutation in reactor facilities are considered. The goals of transmutation and the choice of nuclides to be transmuted are discussed. The concept of radiotoxicity is explained as a measure of the radiological hazard of radioactive nuclides, based on the maximum permissible concentration of nuclides according to the IAEA standards. The problem of the formation of secondary radioactive nuclides in nuclear fuel during generation of neutrons for transmutation is discussed. The advantages and disadvantages of various methods of transmutation in nuclear installations are considered: inclusion of transmutable nuclides in nuclear fuel in fast reactors, transmutation in specialized thermal and fast transmutation reactor installations and ADS systems. The problem of accumulation of highly radioactive actinides in a transmutation facility during long-term transmutation and the problem of a potential hazard of the transmutation facility itself are discussed. The unacceptability of application of common-type power reactors for the transmutation of long-lived fission products is demonstrated.
Assessment of a possibility to use 232U in radioisotope thermoelectric generators
Authors: Kulikov G G , Shmelev A N , Apse V A , Kulikov E G
Published: December 2020

The paper analyzes advantages and drawbacks of the radioisotope thermoelectric generators (RTG) based on application of 238Pu and 232U. Currently, the RTG on 238Pu are widely used for long-term autonomous power supply of spaceships due to the following positive properties of 238Pu: high specific heat generation rate, long half-life, weak emission of neutrons and γ-rays. Isotope 238Pu may be produced by neutron irradiation of 237Np (main component of transuranium radioactive wastes) in nuclear reactors. The paper considers application of 232U for the same purpose because of the following positive properties of 232U: power elevation during initial 10 years of the RTG operation (effect of α and β-emitters in 232U decay chain), long half-life (comparable with 238Pu half-life). Unfortunately, 232U decay chain includes also intense emitters of high-energy γ-rays. As a compromise, a possibility is considered to create the RTG based on mixture of 238Pu with small (below 5%) additive of 232U. Such RTG will be able to keep long-term stable operation at high power level. The following two-step technology is proposed to produce 232U: generation of 231Pa in thorium blanket of hybrid thermonuclear reactors and subsequent neutron irradiation of 231Pa in nuclear reactors till accumulation of significant 232U quantities.
Possible ways to solve the problems of using MOX fuel in thermal reactors
Authors: Kosyakin D A , Stogov V Yu , Korobeinikov V V
Published: December 2020

Modern nuclear power has a number of crucial problems, including the accumulation of spent nuclear fuel (SNF) and the projected shortage of nuclear resources. The conversion to a closed fuel cycle is the most promising solution to these problems. Mixed uranium-plutonium fuel (MOX fuel) has been successfully tested and commissioned under this concept by several European countries. However, its operation in reactors designed for uranium fuel has a number of problems, most of which have been resolved. Nevertheless, the spent MOX fuel has neutronic characteristics that do not allow its reuse in thermal reactors and solve the problem of SNF accumulation. This is due to the accumulation of heavy (even) plutonium isotopes, which are not fissionable in the thermal spectrum. In fast reactors, it is possible to create conditions under which the isotopic composition of plutonium from the spent MOX fuel from thermal reactors changes in such a way that it becomes suitable for reuse in thermal reactors. This process is called improving. The concept for the development of two-component nuclear energy based on the joint operation of thermal and fast neutron reactors and the creation of a closed fuel cycle was adopted in Russia to implement this process and solve crucial problems of nuclear power.
Features of training specialists for responsibility centers of the project direction “Proryv”
Authors: Kutsenko K V , Lavrukhin A A , Pershukov V A , Ternovykh M Yu , Tikhomirov G V
Published: December 2020

National Research Nuclear University “MEPhI” (NRNU MEPhI) is the leading university of the consortium of reference universities of the State Atomic Energy Corporation Rosatom (ROSATOM), a regular supplier of young specialists of the highest level. Since 2014 NRNU MEPhI has been training graduates for responsibility centers of the project direction “Proryv”. University responds quickly to staffing challenges, and provides the project “Proryv” the personnel with relevant unique competencies. These competencies include the ability to apply the knowledge gained to develop a new technological platform for nuclear power with the involvement of uranium-238 and spent nuclear fuel reprocessing products in the fuel cycle. Obtaining such unique knowledge is impossible without the use of external resources, namely, the involvement of leading scientists and practitioners of ROSATOM for conducting classes with students, organizing practices in scientific centers and at nuclear fuel cycle enterprises. The article discusses the features of the organization of the educational process in this area.
Experimental comparison of the measurement results of two different silicon photomultipliers and organic scintillator to detect fast neutrons
Authors: Chergui A C , Popova E V , Stifutkin A A , Dendene O , Ilyin A L , Vinogradov S L , Bychkova O V
Published: December 2020

We report on the study of experimental comparison between the results of two types of silicon photomultiplier (SiPM), to discriminate the signals from fast neutrons and gamma-rays by the digital charge pulse shape discrimination (PSD) method. This uses a total to partial charge ratio analysis. The signals are digitized by a high-speed digital oscilloscope LeCroy WR 620zi with a sample rate of 10 GS/s. This oscilloscope was used to acquire data, which were later processed offline in a specially developed software package written in LABVIEW. The tested detector part consisted from a stilbene crystal (3x3x6 mm3 and 6x6x6 mm3) optically coupled to a SiPM (KETEK 3x3 mm2 and SensL 6x6 mm2 respectively) as a photodetector. Measurements with a Cf-252 source were performed and a figure of merit (FOM) for discrimination between neutron and gamma-ray was calculated for each assembly. The resulting value of FOM for the KETEK 3x3 mm2 SiPM and SensL 6x6 mm2 SiPM was 1.6±0.03 and 1.76±0.05, respectively, the SensL assembly having a slightly better discrimination factor than KETEK one. The obtained results prove a good fast neutron detection performance of the SiPMs, which makes it possible to use these types of neutron detectors in the several fields of radiation protection applications and safety of nuclear facilities.
A new approach of spectral regulation in the pressurized water reactors using Zr rods
Authors: Elazaka A I , Tikhomirov G V
Published: December 2020

The elongation of the fuel cycle period and the reactor reactivity control are crucial for all reactor suppliers. The traditional methods of boric acid, burnable absorbers, and control rods to control the reactor reactivity have their defects. A new method of the neutron spectral shift is studied to perform the reactor reactivity control and maintain the length of the fuel cycle. The neutron spectrum regulation can be achieved with different methods, including the Zr rods insertion in the fuel assemblies as water displacers. In this work, SERPENT2 version 2.1.30 was used to investigate a new fuel assembly design in the basics of Sierpinski carpet geometry to utilize the Zr rods as water displacers. The study of different fuel pitches of the Sierpinski fuel assembly is investigated to choose the reference fuel of the new design. The effect of boric acid concentration increasing and defining the maximum boric acid concentration in the Sierpinski fuel assembly are studied. The primary safety parameters of the Doppler effect and moderator temperature reactivity coefficients calculations approved the safety of the new Sierpinski fuel assembly design. The infinite multiplication factor at different steps of burnup showed the efficiency of the Sierpinski fuel assembly model to control the reactor reactivity. The average breeding factor to the burnup limit of 65 GWd/T is 0.68 in the Sierpinski fuel assembly with the presence of Zr rods.
Effect of gadolinium absorber radial profiling in fuel pins on VVER-1000 assembly neutron-physical characteristics
Authors: Vnukov R A , Zhavoronkova I A , Kolesov V V , Karpovich G V , Teplyakova A R
Published: December 2020

The paper raises the problem of non-optimal use of resources. The purpose is to extend the fuel campaign. An alternative task is to increase the duration of the reactor campaign to increase the flexibility of decision-making during the operation of a nuclear reactor. The paper presents calculations of the profiling of a burnable absorber in fuel assemblies for VVER-1000 reactors. A quantitative assessment of the effect of alternative placement of gadolinium in fuel elements is made. Changes in the burnup of fuel elements in fuel assemblies are noted, as well as an advantage expressed in a change in the kinf. The results showed a strong dependence of the isotopic composition of the peripheral layer on the neutron flux density and a weak dependence of the isotopic composition of the central fuel element with gadolinium layers on the neutron flux density. The burnup when using the iterative process turned out to be impossible to align along the radius presumably due to the production of plutonium. A significant advantage of profiling a fuel cell with gadolinium is expressed in the period before the first overload, with each subsequent overload the efficiency of the technology decreases. However, kinf of the profiled assembly throughout the entire fuel campaign exceeds the kinf of the standard assembly, which indicates the efficient use of a burnable absorber.
Analysis of the connection of an idle MCP with three operating without a preliminary reduction in the power of the VVER-1000 reactor
Authors: Muzafarov A , Nikonov S
Published: December 2020

The paper analyzes the transient process caused by connecting an idle loop (turning on an idle main circulation pump (MCP)) without preliminary reduction in the power of a VVER-1000 reactor plant (RP) operating at a rated power corresponding to three MCPs. The process under consideration is included in the “Reactive accidents” section of materials for justifying the safety of VVER-1000. Modeling is carried out on the example of the 3rd power unit of the Kalinin NPP [1]. For the calculations, we used the improved evaluation code ATHLET [2], which is included in the AC2 software package, officially obtained by the National Research Nuclear University MEPhI on the basis of a license agreement with Gesellschaft fur Anlagen-und Reaktorsicherheit (GRS) gGmbH, Germany [3]. The ATHLET code has been certified in Russia for calculating stationary and transient conditions in water cooled reactors [4]. For the conservatism of the calculation, the study did not take into account the work of the PRL, APR, WP-1, WP-2 and AWP, the functioning of which is aimed at limiting the increase in the reactor power during the transient process. Blocking the signal to turn off the MCP on the fact of a decrease in the level in the SG and of the three ECCS systems, the operation of only one system is taken into account. For a number of reasons, this calculation was carried out for the end of the campaign. Implementation of design safety criteria for the adopted transition scenario is demonstrated.
Investigation the possibility of burning Cm a curium fuel reactor
Authors: Dikova T S , Karazhelevskaya Yu E , Terekhova A M
Published: December 2020

Radioactive waste management is one of the main tasks of the nuclear power industry. Spent nuclear fuel poses a threat to the environment if it leaks from the storage facility. A possible solution to reduce waste storage and reduce the economic pressure of natural uranium shortages is to use minor actinides as fuel for nuclear reactors. This article is dedicated to the possibility of burning Cm in a reactor with curium fuel, as a result of which It can be used as fuel for a nuclear reactor. The purpose of the research is to study the possibility of creating a model of a reactor with curium fuel. Calculations were performed for a simplified single-zone model of the RBEC reactor using the «Serpent» software package. Calculations have shown that the use of the actinides as an alternative fuel is possible. That can later play an important role in reducing emissions of nuclear waste in nuclear power.
Irregularity of plutonium isotopic composition of the BREST-OD-300 initial load
Authors: Karazhelevskaya Y E , Levon M A , Terekhova A M , Zlobin A S
Published: December 2020

This article is dedicated observation of irregularity of plutonium isotopic composition of the BREST-OD-300 initial load. The purpose of the research is to study the effect of the plutonium isotopic composition in the nitride fuel of the BREST–OD-300 reactor core starting load on the reactivity reserve. The calculations is creating by writing simplified three-dimensional geometry of the BREST-OD-300 reactor in software package “SERPENT”. There are five options in the fuel assemblies locations are considered with different cases of using the plutonium isotopic composition with deviations for some isotopes. Calculations have shown that the deviation of the plutonium isotope composition from the design values of the fuel loading of the BREST-OD-300 reactor does not affect the stability of reactivity during fuel burnout within the effective fraction of delayed neutrons. In the course of the research, changes in the effective multiplication coefficient are obtained over five years of reactor operation. The value of this indicator does not depend much on the plutonium deviation in the considered variations in the arrangement of fuel assemblies in the reactor core.
Characteristics of uranium mineralization in the Tin-Seririne sedimentary basin (Algeria)
Authors: Badahmaoui T , Bugrieva E P , Lavrukhin A A
Published: December 2020

This article presents the results of studying the uranium mineralization of various parts of the Tin-Seririne sedimentary basin located in the southern part of the Hoggar massif in south-eastern Algeria. Mineralization of uranium is localized at different stratigraphic levels: in altered rocks of the Archean basement and unconformity overlying basal conglomerates (Tahaggart region), and in Devonian sandstones (uranium ore occurrences Tamart-N-Iblis, Timouzaline, etc.). For laboratory studies, 07 samples were taken: As and A1 granites, Tedjart, Timouzaline and Tamart-N-Iblis sandstones, gneisses and conglomerates of the Tahaggart deposit. The samples were examined using gamma spectrometric, chemical and microprobe analyzes. Mineralization is represented by minerals of hexavalent uranium: autunite, torbernite, carnotite, vanuralite and uranophane. The hypergenesis zone of the deposit, it is noted that the geochemical features of the formation of uranium mineralization are typical for regions of arid climate. The arid climate corresponds to oxidative processes of chemical weathering, with weakly alkaline or neutral uranium-bearing solutions. When studying samples taken from different stratigraphic levels, a difference in mineral composition was noted, which indicates some differences in the conditions of formation of uranium mineralization.
Research study of possibility producing radioisotope Mo-99 in the active core of the BN-600 reactor using an irradiated assembly with a high flux of thermal and resonance neutrons
Authors: Klimenko D S , Ignatiev I A , Kolesov V V , Korobeynikov V V
Published: December 2020

It is fact that production of secondary fuel isotopes (plutonium) is carried out in fast neutron reactors, and the possibility of production of non-fuel radioactive isotopes for use in medicine and industry is being considered. BN-600 has a high power density in the core. This makes it possible to achieve a high rate of fission of target nuclei, which is especially important in the case of the production of radioisotopes, due to their short half-life. To meet the growing demand for isotopes, it is planned to use irradiation devices in high-power sodium fast reactors. This type of irradiation device assumes a massive production of the necessary isotopes. The paper considers the design of irradiation devices for the production of molybdenum-99 isotope in the BN reactor. The presented design of the irradiation assembly contains a moderator in order to combine the advantages of the high neutron flux inherent in fast reactors and the thermal neutron spectrum inherent in thermal reactors.
Modeling the core of a lead-cooled reactor
Authors: Chudinova V A , Nikonov S P
Published: December 2020

This paper presents the results of thermohydraulic modeling of the reactor core with a lead coolant, which is based on the calculation scheme for the ATHLET code, obtained on the basis of open information on the BREST-OD-300 reactor plant. Only the reactor core and methods of its modeling are considered. The work also presents the results on the development of the division of the in-reactor space of the BREST-OD-300 reactor into a system of parallel channels. The subdivision of the in-core space is based on the type and number of different core elements. This way of modeling the core allows you to see changes in different parts of the reactor when calculating transients. The developed model of the partitioning of the in-core space will be further used in the calculation of various transient modes (MCP shutdown, steam generator tube rupture, etc.). Neutron physics is not considered in this paper. There are plans to carry out joint neutron-physical and thermohydraulic calculations using the model from this paper.
Prospective methods for optimization of minor actinides transmutation technology
Authors: Ryzhov S N , Tikhomirov G V
Published: December 2020

Among the various international policies for the management of spent nuclear fuel and radioactive waste (RW), an important issue is the need to reprocess this waste. The aim of this work is to analyze current modern methods for transmutation of minor actinides (MA) in the reactor cores of thermal, fast (with homogeneous and heterogeneous placement) and in accelerated driven systems in order to identify factors limiting the efficiency of transmutation. This work is an analytical review and it defines the main methods for removing the limitations of the effectiveness of the transmutation process. On the basis of MA formation sources data and MA decay chains, namely americium, neptunium and curium, as well as transmutation methods in the latest reactor systems, factors limiting the efficiency of the transmutation process and methods of reducing their influence are investigated. The main factors are: an increased level of gassing during transmutation, industrial restrictions and the influence of the transmutation process on the processes occurring in the core during transient processes. The main current problem of transmutation is the high activity in terms of heat release level and neutron emission of irradiated assemblies due to the presence of curium isotopes.
Development and testing of algorithms for performing computation of detector readings from a pulsed neutron source
Authors: Gurevich M I , Kalugin M A , Kuznetsov A N , Oleynik D S , Shkarovsky D A
Published: December 2020

To provide the possibility of computation of detector readings from a pulsed neutron source (time dependent readings) the development of algorithms and their realization to upgrade precision Monte Carlo code MCU are considered in this work. New version of the MCU code was tested, which included comparison with experimental results. The experiments were made by Lawrence Livermore National Laboratory in the late sixties. Neutron transport from a pulsed source through layers of various materials was studied in these experiments. The comparison of the MCU calculation results obtained for these experiments with the corresponding MCNP-6 calculations results is also given in this work.
Testing the multigroup, group and subgroup options of the CONSYST / ABBN-RF system on criticality calculations of fast reactor models with MNUP fuel
Authors: Ternovykh M Y , Bogdanova E V
Published: December 2020

The unified code CONSYST-2020 for neutron constants preparation and the ABBN-RF-2020 neutron data library are being testing as part of the new generation codes development for neutronic calculations of fast reactors with mixed nitride uranium-plutonium fuel (MNUP). Testing was carried out on prototype models of fast reactors with MNUP fuel. The errors of the multigroup, group and subgroup approximation are analyzed in comparison with the calculations performed using point-wise cross-sections libraries. The results obtained with point-wise cross-sections libraries are accepted in the final cross-verification as reference results. An assessment was made of the influence of approximations associated with averaging and preparing group cross-sections, and methodological errors determined by the selected spatial and angular computational grids. It was shown that the transition to the direct use of 299-group blocked constants reduces the error to 0.1 – 0.2%. The assessment of the efficiency of using the subgroup approximation shows the possibility of reducing the constant component of the error below 0.05%.
Development of virtual analogues of nuclear facilities in virtual reality
Authors: Dashanova E A , Zadeba E A , Kiryukhin P K , Pugachev P A , Romanenko V I , Tikhomirov G V , Khomyakov D A , Shcherbakov A A , Yushin I M
Published: December 2020

Using virtual reality technology - a modern trend. The nuclear industry is no exception. This article provides an overview of mathematical models used to create virtual analogue of critical assembly Godiva in virtual reality. Godiva - there is a simple example that allows to hone techniques for creating more complex virtual analogues of nuclear reactors and nuclear facilities. Mathematical models include stationary and dynamic ones. The stationary model is based on data from calculations carried out using Monte Carlo programs such as MCU, Serpent and Geant4. An approach is also described that makes it possible to calculate the reverse multiplication from the values of the effective multiplication factor for various states of the subcritical assembly. The dynamic model allows one to calculate the neutron-physical characteristics of the supercritical assembly during fast processes such as a neutron burst. In conclusion, there are other examples of virtual analogs created using similar approaches.
Use of Am-241 in RTGs
Authors: Mikhalev A V , Chernov D O , Korobeinikov V V
Published: December 2020

Currently, transuranic elements are a serious problem. They are formed in spent nuclear fuel as a result of the operation of reactors. These elements have a sufficiently high radioactivity and a huge half-life, thus they remain dangerous for a very long time and must be burned out on specialized reactors. However, not all of them can be classified exclusively as waste. Am-241, which has a low heat release due to its alpha decay, can be used as a radionuclide source for RTGs. However, this nuclide can maintain a fission chain reaction and emits gamma rays as a result of decay. The article investigates some properties of possible devices, as well as an assessment of the radiation protection for such devices.
Adaptation of the model method for estimating sample uncertainty
Authors: Dashanova E A , Shcherbakov A A
Published: December 2020

This approach to assessing the uncertainty of measurements of sample activity was developed taking into account the requirements of the laboratory for dosimetry of incorporated radionuclides within the framework of the Methodology for measuring the activity of uranium isotopes by the spectrometric method after extraction-chromatographic isolation from urine samples. A detailed analysis of the sources of uncertainties in the activity of the sample was carried out: the uncertainty of the chemical yield, the uncertainties in the measurements of the activity of the sample, the working radioactive solution (WRS), and the uncertainty in the volume. All uncertainties are divided into two types: type A and type B. Estimation of measurement uncertainty is based on a model approach. The procedure for estimating the uncertainty of the activity of the sample was successfully verified using the specialized software GUM Workbench Pro during their construction.
The influence of neutron reflector with special properties on fast reactor kinetics
Authors: Kudriavtseva A S , Shmelev A N
Published: December 2020

The paper substantiates the possibility of increasing the safety of fast reactors by surrounding the reactor core with a neutron reflector with special properties. The particular case of using lead isotope as a neutron reflector has been considered in the lead-cooled fast reactor in an exemplary manner. An asymptotic point kinetics model, which takes into account neutrons returning from the reflector to the reactor core and participating in the development of fission chain reaction, was proposed for assessment of the emerging effects. The in-hour equation for fast reactors, surrounded by a neutron reflector with special properties, has been developed. It was revealed that the neutron lifetime can be substantially increased. Therefore, the contribution of the neutron reflector would mitigate the consequences of accidents when inserted reactivity exceeds the effective fraction of delayed neutron. In addition, the maximum rates of power increase have been calculated for different cases of reactivity insertion. The obtained results have considerable practical value for scientific and advanced studies of reactor accidents.
Comparing Metrological Characteristics of Methodologies for Determining Uranium Enrichment Using NaI and LEGe Detectors
Authors: Bartev N O , Aleeva T B , Zubarev V N
Published: December 2020

The purpose of this work was to compare metrological characteristics of methodologies for determining uranium enrichment using different types of detectors and the IMCA software. This software includes several programs (applications), two of which were used in this work: IMCN was used for NaI detector, and IMCG was used for LEGe detector. The principle of enrichment measurement is that the uranium enrichment is directly proportional to the count rate at the 185.7 keV peak resulting from decay of 235U, provided that the sample’s thickness is sufficient (“infinite thickness” method). Based on the results of repeated measurements of samples with known enrichment, metrological characteristics of methodologies for different count times were calculated and compared. Analysis of the results led us to the following conclusions: reproducibility of results when performing measurements using LEGe detector is just as good as when using NaI detector; at that, uncertainty reported by the IMCG program is almost the same as the reproducibility estimate, while the IMCN program reports uncertainties that are several times smaller than the estimated reproducibility.
Determination of integral turbulence model parameters as applied to the calculation of flows in fuel assemblies of fast reactors in porous-body approximation
Authors: Vlasov M N , Korsun A S , Maslov Yu A , Merinov I G , Kharitonov V S
Published: December 2020

This work aimed to correct the integral turbulence model developed earlier for assemblies of smooth rods. Two variants of the fuel assembly design were considered. In the first variant, the fuel rods were spaced using spacer grids. The presence of a spacer grid does not require a change in the form of the system of equations but leads to a change in the form of the resistance tensor and the generation of turbulence in the spacer grid region. In the second variant, a wire-wrapped fuel bundle was analyzed. The presence of a wire-wrapped fuel bundle requires an additional term in the equation for the conservation of momentum and change in the form of the resistance tensor. The simulations were obtained by CFD code ANSYS CFX and aimed at the determination of parameters involved in an integral model of turbulence being developed for modeling nuclear-reactor cores and heat exchangers in anisotropic porous-body approximation.
Investigation of radiation levels in the region of fuel-transfer cask for transportation of spent fuel of light-water reactors
Authors: Shorov V Y , Ternovykh M Y , Gerasimov A S
Published: December 2020

The paper formulates the main problems associated with research on transmutation, which should be paid attention to by today’s young researchers. The processes of production of hazardous nuclides during transmutation in reactor facilities are considered. The goals of transmutation and the choice of nuclides to be transmuted are discussed. The concept of radiotoxicity is explained as a measure of the radiological hazard of radioactive nuclides, based on the maximum permissible concentration of nuclides according to the IAEA standards. The problem of the formation of secondary radioactive nuclides in nuclear fuel during generation of neutrons for transmutation is discussed. The advantages and disadvantages of various methods of transmutation in nuclear installations are considered: inclusion of transmutable nuclides in nuclear fuel in fast reactors, transmutation in specialized thermal and fast transmutation reactor installations and ADS systems. The problem of accumulation of highly radioactive actinides in a transmutation facility during long-term transmutation and the problem of a potential hazard of the transmutation facility itself are discussed. The unacceptability of application of common-type power reactors for the transmutation of long-lived fission products is demonstrated.
Parallel calculation of the stationary diffusion equation
Authors: Soldatov E O , Volkov Yu N , Zizin M N
Published: December 2020

Considering the complex neutron-physical systems with the number of calculation points than 1 million, the calculation time can be an hour or more, and in case of non-stationary process with the small step of time, the waiting can be a month. The aim of the study is to develop effective techniques for the stationary computational modeling using parallelization technology to imply in non-stationary calculations. The parallelization scheme with height decomposition for stationary model was developed. The calculated speedup on the parallel part of the code are in good agreement with the linear dependence. The theoretical possible acceleration was derived using Amdal’s law. Comparing the obtained and theoretical curves demonstrates that the developed parallelization scheme has less acceleration due to losses. The losses and their relative contribution were identified.
Staff training experience for Uzbekistan nuclear industry in Branch of MEPhI in Tashkent
Authors: Bayaskhalanov M V , Maslov Y A , Sanetullaev A , Skrytnyy V I
Published: December 2020

The article describes history of creation Branch of National Research Nuclear University MEPhI in Tashkent, which will provide training of highly qualified national staff for solving the most important tasks of Uzbekistan nuclear industry.
Structural analysis across length scales of the scorpion pincer cuticle
Authors: Kellersztein Israel , Greenfeld Israel , Wagner H Daniel
Published: December 2020

Biological structures such as bone, nacre and exoskeletons are organized hierarchically, with the degree of isotropy correlating with the length-scale. In these structures, the basic components are nanofibers or nanoplatelets, which are strong and stiff but anisotropic, whereas at the macrolevel, isotropy is preferred because the direction and magnitude of loads is unpredictable. The structural features and mechanisms, which drive the transition from anisotropy to isotropy across length scales, raise fundamental questions and are therefore the subject of the current study. Focusing on the tibia (fixed finger) of the scorpion pincer, bending tests of cuticle samples confirm the macroscale isotropy of the strength, stiffness, and toughness. Imaging analysis of the cuticle reveals an intricate multilayer laminated structure, with varying chitin–protein fiber orientations, arranged in eight hierarchical levels. We show that the cuticle flexural stiffness is increased by the existence of a thick intermediate layer, not seen before in the claws of crustaceans. Using laminate analysis to model the cuticle structure, we were able to correlate the nanostructure to the macro-mechanical properties, uncovering shear enhancing mechanisms at different length scales. These mechanisms, together with the hierarchical structure, are essential for achieving macro-scale isotropy. Interlaminar failure (ILF) analysis of the cuticle leads to an estimation of the protein matrix shear strength, previously not measured. A similar structural approach can be adopted to the design of future synthetic composites with balanced strength, stiffness, toughness, and isotropy.
Increasing importance of temperature as a contributor to the spatial extent of streamflow drought
Authors: Brunner Manuela I , Swain Daniel L , Gilleland Eric , Wood Andrew W
Published: December 2020

Widespread streamflow droughts can pose substantially greater societal challenges than spatially less extensive events because of the complex realities of trans-regional water management. In a warming climate, drought spatial extent may change along with changes in underlying hydro-meteorological contributors. Here, we assess changes in streamflow drought spatial extent over the period 1981–2018 across the conterminous United States, and how the importance of potential hydro-meteorological contributors has changed over time. We first derive a monthly time series of drought spatial extent and look at trends in streamflow drought spatial extent. We then determine the spatial percentage ‘overlap’ of precipitation droughts, temperature anomalies, snow-water-equivalent deficits, and soil moisture deficits with the area under streamflow drought to look at the changing influence of these contributors on spatial extent. Our results show that (1) the spatial extent of droughts has increased, mainly because of increases in the extent of small droughts; (2) streamflow drought extents overall substantially overlap with soil moisture deficits and the relationship of drought to precipitation and temperature anomalies varies seasonally; and (3) the importance of temperature as a contributor to drought extent has increased over time. We therefore conclude that continued global warming may further increase drought extents, requiring adaptation of regional drought management strategies.
SU(2|1) supersymmetric spinning models of chiral superfields
Authors: Sidorov Stepan
Published: December 2020

We construct SU(2|1), d = 1 supersymmetric models based on the coupling of dynamical and semi-dynamical (spin) multiplets, where the interaction term of both multiplets is defined on the generalized chiral superspace. The dynamical multiplet is defined as a chiral multiplet (2, 4, 2), while the semi-dynamical multiplet is associated with a multiplet (4, 4, 0) of the mirror type.
Absence of nematic quasi-long-range order in two-dimensional liquid crystals with three director components
Authors: Delfino Gesualdo , Diouane Youness , Lamsen Noel
Published: December 2020

The Lebwohl–Lasher model describes the isotropic–nematic transition in liquid crystals. In two dimensions, where its continuous symmetry cannot break spontaneously, it is investigated numerically since decades to verify, in particular, the conjecture of a topological transition leading to a nematic phase with quasi-long-range order. We use scale invariant scattering theory to exactly determine the renormalization group fixed points in the general case of N director components (RP

N−1 model), which yields the Lebwohl–Lasher model for N = 3. For N > 2 we show the absence of quasi-long-range order and the presence of a zero temperature critical point in the universality class of the O(N(N + 1)/2 − 1) model. For N = 2 the fixed point equations yield the Berezinskii–Kosterlitz–Thouless transition required by the correspondence RP
1 ∼ O(2).
Study on the Effects of Agricultural Land Transfer on Agricultural Economic Growth
Authors: Li Chunmei , He Ge
Published: December 2020

This study aims to examine the impact of agricultural land transfer on agricultural economic growth by using annual time series data of Guangxi province of China over the period of 2003 to 2015. we employed ARDL-bound test to test the long-run and short-run relationship between dependent and independent variables. The empirical results show that there is no significant short-term impact on agricultural economic development, and the coefficient is 0.0399. In the long run, agricultural land transfer has a significant impact on agricultural economic growth, with a coefficient of 0.1857. Agricultural land transfer restraining the drag effect of rural surplus labour force on agricultural economic growth and did not increase the output effect of agricultural machinery. Our findings conclude that the adjustment caused by the transfer of agricultural land is beneficial to the development of agricultural economy for a long time, and plays an important role in the allocation of agricultural labour force but not in agricultural capital investment.
Development Status and Trend Analysis of Four-way Purification Technology for Automobile Exhaust
Authors: Hui Wang Ying , Song Liang Qiu , Sheng Lu Zhen , Long Wang Jiu , Xin Chen Nan
Published: December 2020

Automobile exhaust has seriously polluted the environment and endangered human health, in order to satisfy strict China VI regulation, four-way purification technology will become effective engine after-treatment technology for purifying automobile exhaust. This paper firstly introduces reaction mechanism of purifying particular matter, nitrogen oxide, carbon monoxide and hydrocarbon. Secondly, this paper summaries the development status of four-way purification technology for automobile exhaust from two aspects. Finally, this paper suggests that automobile exhaust can be purified by plasma combined with modified perovskite catalyst technology, this method has the advantages of low back pressure, low cost, simple structure and strong stability compared with the traditional automobile exhaust purifier, which canachievethe purification of PM, NOx, CO and HC simultaneously, and open up a new direction for automobile exhaust purification technology.
Construction of knowledge graph of forest musk deer based on BiLSTM-CRF model and DPA method
Authors: Yang Chuqiao , Wang Haiyan , Sai Jingyan , Zhang Peiwei , Yan Mengyao
Published: December 2020

Forest musk deer is a national key protected species, but due to overhunting and habitat destruction, wild musk deer has disappeared in large areas. Constructing a knowledge graph in the field of forest musk deer can standardize the relevant knowledge in the field of forest musk deer and lay a good foundation for wildlife protection and ecological construction. In order to construct the knowledge map of the forest musk deer, the entities were further subdivided first, and the BiLSTM-CRF model was used to identify the entities of the BIO-labeled data. After analysis, it was found that the model used in the experiment performed better. Secondly, the Dependency Parsing Analysis method was used to identify the relationship, and the relationship between the entities was smoothly extracted.Finally, the Neoj4 graph database was used to realize the storage and visualization of the knowledge graph of the forest musk deer. This research transforms the unstructured text in the field of forest musk deer into structured data. Through the systematic sorting of relevant knowledge in the field of forest musk deer, it can provide wildlife protection, artificial breeding of forest musk deer, intelligent knowledge services and other aspects some new technical means in the field of forest musk deer.
Comprehensive Water Resource Management Strategies in Arid Oasis Regions: Taking Minqin County as an Example
Authors: Ren Xiaoyan , Yin Qiang , Zhang Hengjia
Published: December 2020

Minqin County is the last line to block the closure of the Tengger Desert and Badanjilin Desert. For more than half a century, due to the influence of natural factors and human activities, the ecological environment of Minqin County has seriously deteriorated. The sustainable development of Minqin County has been restricted because of the unreasonable development and utilization of water resources. This paper analyses the problems and causes of the ecological environment, and reviews the main measures of water resources protection in Minqin County, including the implementation of wells closing and fields burying policy, the promotion of agricultural water-saving technology, the adjustment of planting and industrial structure, ecological migration, as well as the promotion of water rights and water price reform, the optimization of water structure, and discusses the achievements achieved. This paper summarizes the measures and effects of comprehensive control and provides a reference for the ecological restoration of the follow-up study area.
The optimization design and test of camfull-row-pick-up seeding mechanism
Authors: Li Liangliang , Niu Wenjing , Qi Zhengdong , Chen Jie , Guodang Lian , Haiyang Tang
Published: December 2020

The mechanism components and working principle were analysed, and then cam mechanism was simplified into slider-crank mechanism to facilitate the establishment of kinematic model. The target optimization function for structural parameters was solved out via mathematical model combined with the transplanting requirements, then a computer-aided analysis program based on Visual Basic 6.0 was developed for optimizing structural parameters of the mechanism. According to the optimized structural parameters, the three-dimensional model of mechanism was established and the automatic seedling pick-up test-bed was conducted. The analysis of kinematic simulation and the test of prototype test were carried out. The success rate of picking up seedlings reaches 95% and efficiency of taking seedling is 3600 strains per hour. The cam full-row-pick-up seedling mechanism is feasible and effective to achieve the operation requirements of whole-row-pick-up seedling.
Marine factory farming techniques and equipment
Authors: Xiao Jialuan , Zhang Yingyu
Published: December 2020

Marine factory farming is a short-lived but rapidly developing industry. Traditional aquaculture occupies a large area of water resources. At the same time, it has great damage to the environment and is not in line with the idea of sustainable development. Now marine resources have gradually become a hot topic. The marine factory farming industry combines a variety of emerging and traditional industries, such as machinery and automation, chemistry, biology, computer science, etc., have great development potential today. This paper discusses the technology and equipment in the process of marine factory culture from the basic situation of marine factory.
Target characteristic satellite observation modeling and artificial intelligence integrated application
Authors: Li Huizi , Hou Wei , Zhang Lili , Zhao Xiqi , Liu Zongyue
Published: December 2020

This article focuses on the core key and weak links of artificial intelligence applications in the field of satellite earth observation, carries out satellite reconnaissance modeling and simulation of different objects and different targets, and satellite space-based measurement and optimization of target characteristics, and establishes space-based target characteristics database and services. The platform makes it an infrastructure resource for artificial intelligence applications in the field of domestic satellite earth observation. Through the integrated application of artificial intelligence, the link between the target characteristics and the application is opened to promote the development of the satellite remote sensing application industry.
Research on Influencing Factors of Regional Economic Green Growth under Carbon Emissions constraint
Authors: Li Zhiyu , Zhou Yatong , Cai Songfeng , Lv Pengjuan
Published: December 2020

Promoting the green revolution is not only an urgent need to realize the coordinated development of economy, but also a strategic choice to cope with global climate change and reduce CO2 emissions. This paper incorporates carbon emission data into the economic growth analysis model, uses the SBM-DEA model to measure the green total factor productivity of each region, and uses panel data to investigate the factors affecting regional economic growth under carbon emission constraints. The research results show that industrial agglomeration, scientific and technological progress and human resource factors have a significant role in promoting the green growth of the regional economy, and energy consumption efficiency, investment efficiency, the structure of export products have a restrictive effect on the regional green growth. Therefore, it is necessary to more closely integrate the adjustment of industrial structure with technological innovation, improve energy utilization efficiency, and at the same time promote the innovation of financial policies to provide lasting impetus for the regional green sustainable development.
Predictive Analysis of Characteristic Variation and Evolution of Rainfall Cycle in Guangzhou
Authors: Liu Pei , Xu Wei , Pengfei Huang
Published: December 2020

Due to the influences of global warming, urban rainfall has changed significantly. Based on the annual rainfall data of Guangzhou from 1952 to 2019, the characteristics of interannual variation are statistically analyzed. The periodic characteristics of rainfall variation and its development trend prediction are studied by using non-parametric Mann-Kendall test, wavelet analysis and neural network methods. The results show that: After 1993, there was an increasing trend of rainfall in Guangzhou, and a sudden change in 2009, and the increasing trend of rainfall became more obvious. The 30a cycle scale of rainfall in Guangzhou shows the most significance. The average cycle of rainfall changes is around 19a. The rainfall in Guangzhou in 2020 is predicted to be 2,628.9mm, and the rainfall will be in “dry water” period from 2021 to 2029. The rainfall characteristics in Guangzhou are continuously changing under the influence of climate warming. This study is of great significance to reveal the recent drought and flood characteristics of the region.