{"title":"Acceleration of resource tests of spacecraft polymers for resistance to long-term influence of atomic oxygen in the Earth ionosphere","authors":"V. Shuvalov, S. N. Kulagin, D. Lazuchenkov","doi":"10.15407/knit2021.04.054","DOIUrl":"https://doi.org/10.15407/knit2021.04.054","url":null,"abstract":"The procedure of accelerated resource tests of spacecraft polymers for their resistance to the long-term influence of atomic oxygen (AO) in the Earth's ionosphere at altitudes from 200 to 700 km has been developed. The procedure involves irradiation of polymers with high-energy ions of atomic oxygen and the use of a kapton-H polyimide as reference material. The condition of equivalence of the \" atomic oxygen - polymer\" interaction in the ionosphere and on the laboratory set is the equality of tested material mass loss. The basis for substantiating the procedure of accelerated tests is the result: when irradiating the kapton-H polymer with high-energy atomic oxygen ions in the energy range from 30 to 80 eV, the degradation of polyimide is determined by the process of chemical etching of the material. To substantiate the procedure of accelerating resource tests of polymeric structural materials of spacecraft for resistance to long-term action of atomic oxygen flows, the dependences of mass loss and volumetric mass loss factor (reactivity) of kapton-H polyimide and Teflon FEP-100A on fluence and energy of the atomic oxygen ions have been obtained. It is shown that when irradiating kapton-H polyimide with atomic oxygen ions with the energy of 30 to 80 eV, the material mass loss due to chemical etching is about an order of magnitude greater than the mass loss due to kinetic sputtering. When the kapton-H polymer is irradiated with high-energy atomic oxygen ions, the coefficient of acceleration of the resource tests and the fluence of atomic oxygen are about two orders of magnitude greater than the coefficient of acceleration obtained using atomic oxygen ions with an energy of 5 eV.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67116964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The global seismic activity influence on process in atmosphere and ionosphere","authors":"I. Zakharov, L. Chernogor","doi":"10.15407/knit2021.05.019","DOIUrl":"https://doi.org/10.15407/knit2021.05.019","url":null,"abstract":"In recent decades, ideas about earthquakes (EQ) have been formed as a final stage of a planetary continuous self-organizing tectonic process with periods of accumulation and relaxation of tectonic stresses. However, the scientific literature still presents studies of the response of atmospheric and ionospheric processes to individual strong EQs. In this paper, for the first time, the relationship between processes in the lithosphere, troposphere, and ionosphere is considered, taking into account new ideas about the seismic process as a global phenomenon and on the background of processes caused by space weather. Both planetary data (EQ, total electron content (TEC) of the ionosphere) and data (atmospheric pressure, critical frequency of the F2 layer of the ionosphere) of widely spaced observation points in the western and eastern hemispheres were used. To increase the reliability of statistical results, 4 independent databases of daily data for 2007–2015 were used. Stable effects of global seismic activity (GSA) in the considered parameters are established. Thus, the critical frequency of the F2 region with a sharp increase in the GSA increases by 0.4–0.5 MHz. This effect is quite stable and manifests itself almost simultaneously at ionospheric stations of the eastern and western hemispheres, as well as in planetary TEC values. At the same time, in the ionospheric variations, as before, the influence of both the troposphere (especially at a low level of solar activity) and space weather is traced, the characteristics of which in 75 % of cases also show an association with GSA. Therefore, space weather often but not always can act as a trigger on the EQs. In general, in the western hemisphere, the minimum atmospheric pressure occurs earlier than in the eastern, which leads to a noticeable increase in the pressure difference between the hemispheres by 10 mm. Hg., that indicates the relationship between global seismicity and global atmospheric circulation. The established GSA effects, as a rule, have the character of not a local short-term burst, but a jump followed by a gradual decrease (increase) of the index until the next active period (saw-toothed curve), i.e., the influence of the lithosphere on the overlying layers is continuous and is cyclical in nature, probably due to the cyclical nature of tectonic processes. Most likely, several different couplings between geospheres are realized at the same time, partially synchronized by changes in space weather, which requires new physical mechanisms to explain them.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67116684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Zolotko, O. Zolotko, O. Sosnovska, O. S. Aksyonov, I. Savchenko
{"title":"Tte stage deorbiting with a deceleration pulse detonation engine","authors":"O. Zolotko, O. Zolotko, O. Sosnovska, O. S. Aksyonov, I. Savchenko","doi":"10.15407/knit2021.04.032","DOIUrl":"https://doi.org/10.15407/knit2021.04.032","url":null,"abstract":"The article discusses the issues related to reducing the amount of space debris from rocket stages. The main ways to remove the separable part of a rocket from a space orbit are: the usе of a deceleration detonation propulsion system; gasification of fuel residues and the use of a gas-reactive deceleration pulse system; continuation of the work of the main propulsion system after the separation of stages; the use of a harpoon to capture the rocket stage and the use of sail for its further braking; the use of anti-missile or combat lasers to destroy a stage on the orbit followed by the stage fragments’ burning in the Earth’s atmosphere. To select the optimal method for removing from the orbit the separated part of a space rocket, the arithmetic progression method was applied. It has certain advantages over the classical hierarchy analysis method and has no inherent disadvantages of this method. A ranked row of solutions was obtained according to the five most significant performance criteria, and its stability was proved. A new deceleration detonation propulsion design scheme is proposed. Detonation burning of residual fuel components provides the maximum possible value of the deceleration thrust impulse. Using the example of the second stage of the “Zenit” launch vehicle, we analyzed the nature of the dependence of the entry angle into the atmosphere on the important characteristic parameters: the deceleration speed impulse, the entry speed into the Earth’s atmosphere of the separated launch vehicle stage, the required value of the specific thrust impulse of the deceleration propulsion system. A new analytical formula has been obtained, which connects the thrust and specific thrust impulse values of the detonation engine with the determined detonation process parameters. The results of the computational experiment were compared with the results of calculating the specific thrust impulse using the new formula for oxygen-based fuel compositions, known experimental data, and numerical simulation data of other authors. The data obtained in this study make it possible to evaluate the design parameters of the deceleration detonation engine at the stage of analyzing technical proposals.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67116838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. L. Makarov, Dnipropetrovsk Ukraine Yangel Yuzhnoye State Design Office, K. Belousov, D. N. Svinarenko, V. S. Khoroshylov, D. Mozgovoy, V. M. Popel', Dnipro Ukraine Yuzhnoye State Design Office
{"title":"Automatized recognition of urban vegetation and water bodies by Jilin-1А satellite images","authors":"A. L. Makarov, Dnipropetrovsk Ukraine Yangel Yuzhnoye State Design Office, K. Belousov, D. N. Svinarenko, V. S. Khoroshylov, D. Mozgovoy, V. M. Popel', Dnipro Ukraine Yuzhnoye State Design Office","doi":"10.15407/knit2021.04.042","DOIUrl":"https://doi.org/10.15407/knit2021.04.042","url":null,"abstract":"The results of testing the developed techniques for automatized recognition of vegetation and water bodies on the urban territory by multispectral images from the Jilin-1А satellite are given.The research included automatized recognition of vegetation and water bodies on the selected observation territory based on images with super high spatial resolution in the visual and infrared range and consequent comparison of the obtained results with the results of visual decoding. The obtained results of processing the images from the Jilin-1А satellite in accordance with the proposed techniques confirmed the sufficiently high accuracy of automatized edge enhancement of recognized objects as compared to the results of interactive visual recognition of these images. Different test areas provided a good separation of vegetation and water types with the same thresholding customization. The accuracy of automatized classification of vegetation and water bodies (without considering the standard errors) for different test areas was within 81...92%, and values of kappa-coefficient were within 0.68 to 0.85. Comparison of normalized index images received from Jilin-1А and Sentinel-2A satellites showed slight discordance in NDVI values and significant discordances for NDWI and MNDWI that are caused by the usage of different spectral channels (SWIR and NIR). These discordances can be sufficiently reduced when using correction coefficients.Analysis of the influence of output image resolution reduction (from 10 to 8 bit) and subsequent informational compressing (JPEG lossy and JPEG2000 lossless) on results of automatized recognition of vegetation and water bodies confirmed the validity and efficiency of these techniques. The volume of saved and transmitted files significantly decreased (in 80…100 times) with a slight reduction of classification accuracy (by 1...2 %). The proposed techniques make it possible to increase significantly the efficiency and probability of renewing maps of big cities and to reduce financial expenditures as compared to the traditional ground GPS-surveying and aerosurveying. The high-level automatization of image processing and minimization of necessary calculations (as compared to techniques that use complex classifiers and neural networks) allow to implement the developed technique as a geographic information web service that satisfies the needs of a wide circle of government services and commercial structures and can be useful for megalopolis population and tourists.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67116854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Participation of the Kharkiv Astronomical Observatory and its staff in the Soviet Space Program in 1960-ies","authors":"M. Balyshev, Yu.Yu. Koval","doi":"10.15407/knit2021.05.086","DOIUrl":"https://doi.org/10.15407/knit2021.05.086","url":null,"abstract":"The article is devoted to the studying of documentary facts on the history of astronomy of the 1960s. Its purpose is to highlight the events related to the participation of the Kharkiv astronomical observatory in the Soviet space program in a certain period. The chronology of involvement of Kharkiv astronomers in programs on development and functioning of objects «V-67», «Е-7», «Е-8», «L-3», «М-69», creation of artificial Lunodrome, processing of photographic materials, that were obtained by spacecraft «Lunar orbiter 2», «Ranger 7», «Surveyor 1», «Luna-9», «Luna-12», «Luna-13», and «Zond-3» are considered. The directions of scientific research in projects «Altai», «Atlas», «Luks», and others of the Astronomical observatory of O.M. Gorky Kharkiv State University are analyzed. The main tasks that the Kharkiv astronomical observatory carried out in the 1960s were found next: photometric studies of details on the reverse side of the Moon; study of the physical, mechanical, and chemical properties of the lunar soil and its optical properties; photometric analysis of certain areas of the lunar surface; photometric calculations necessary for the design of orientation systems of automatic interplanetary stations; study of the luminosity of the lunar surface. The retro-information resources, which were firstly involved into consideration, provided a chronological sequence of events related to the participation of the University observatory in the development and functioning of artificial space objects during the given period. These resources helped to specify the achievements of Kharkiv astronomers in the Soviet program of space exploration and to prove (or clarify) some little-known facts.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67117218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Morpho-physiological reactions of gravisensitivity and adaptation to UV-radiation of the moss Bryum Caespiticiumhedw. from Antarctica","authors":"N. Kyyak, O. Lobachevska, Y. Khorkavtsiv","doi":"10.15407/knit2021.05.047","DOIUrl":"https://doi.org/10.15407/knit2021.05.047","url":null,"abstract":"The adaptive physiological reactions of the moss Bryum caespiticium Hedw. from Antarctica to the influence of UV radiation and gravimorphoses as a factor of adaptive plasticity, associated with environmental conditions, were studied. As a control, B. caespiticium plants were collected in the Nature Reserve “Roztochchia” (Lviv region). In investigations, we used a sterile laboratory culture of mosses grown under controlled conditions in a phytotron. Moss shoots were irradiated with UV rays generated by an ultraviolet lamp OSRAM with an intensity of 4 kW/m2, which caused 50 % inhibition of plant regeneration (ED50). Physiological parameters were determined 24 h after exposure to UV radiation. The influence of gravity on the morphological form of B. caespiticium gametophyte turf and the interaction of light and gravity in gravi-/phototropism as a manifestation of gravimorphoses adaptability were analyzed. One of the objectives was to investigate the formation of gravimorphoses as a result of the initiation of cells’ branching processes and the formation of gametophore buds and to evaluate their role in the life cycle of B. caespiticium under extreme conditions. For this, we determined the branching coefficient of the gravitropic protonema, the inclination angle of the branches and the buds’ development depending on the interaction of photo- and gravitropism, under the influence of red and blue light, and the effect of UV on gravisensitivity. The influence of physiologically active red and blue light on the branching activity and bud formation on the gravitropic protonema of the Antarctic moss B. caespiticium was investigated. It was found that red light mainly inhibited graviperception and gravitropic growth of protonemata cells, resulting in a change of the response to gravity, but initiated high branching activity and, accordingly, another morphological form of turf. After the influence of the blue light, intensive bud formation and gametophore development were observed. Thus, gravitation promoted morphological variability and changes in the functional activity of cells at the juvenile stage of the protonemata development, which is important for the survival of the moss under extreme environmental conditions. After UV irradiation the gravisensitivity of the B. caespiticium protonemata decreased. However, due to the resistance of the moss sample from Antarctica to the prolonged influence of UV rays, gravitropic growth was not completely blocked, as in plants from the Lviv region. The effect of the ultraviolet irradiation on the antioxidant activity, the content of soluble (vacuolar) and cell wall-bound fractions of UV-absorbing phenolic components, flavonoids content and their absorption spectra, as well as the amount of carotenoids and anthocyanins in B. caespiticium shoots, were determined. It was established that B. caespiticium plants from Antarctica have 1.5 times higher antioxidant activity compared to plants from the Lviv region, which confi","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67117081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"International legal principles governing exploration of Moon, Mars and other celestial bodies' resources","authors":"N. Malysheva","doi":"10.15407/knit2021.04.074","DOIUrl":"https://doi.org/10.15407/knit2021.04.074","url":null,"abstract":"The article examines the latest trends in the development of international legal relations in the field of exploration and use of celestial bodies’ resources, which was prompted by the United States' initiation of the international program \"Artemis\". Nine countries of the world, including Ukraine, have joined this program, formalizing their intentions by signing the so-called Artemis Accords. Given that the international legal regime for the exploitation of the resources of Moon, Mars, asteroids, and other celestial bodies is still not defined, and there is no unity in the doctrine of space law in this regard, the article attempts to determine the legal basis for Ukraine's participation, the opportunities that open up for it, as well as the tasks that arise in this regard for the domestic entities of space activities and the State, which is responsible for all space activities carried out under its jurisdiction.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67116542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Assessing aquatic enviromnemt quality of the urban water bodies by system analysis methods based on integrating remote sensing data","authors":"O. Fedorovsky, A. Khyzhniak, O. Tomchenko","doi":"10.15407/knit2021.05.011","DOIUrl":"https://doi.org/10.15407/knit2021.05.011","url":null,"abstract":"The work presents the comprehensive methodology for assessment of the state of the urban aquatic environment such as Lakes Opechen, Verbne, and Redkyne in Kyiv using the methods of system analysis. The methodology includes structural-textural analysis of the satellite images and the method based on statistical criteria. The spectral-texture analysis of the satellite images was used to get input information for remote assessment of reservoirs as index images: Normalized Difference Pond Index (NDPI), Normalized Difference Turbidity Index (NDTI), and Normalized Difference Algae Index (NDAI) computed from the Sentinel-2. The surface temperature distribution was estimated from the Landsat 8. The method based on statistical criteria is used for a detailed assessment of the aquatic environment using the obtained indexed images and the corresponding cartographic representation of the water quality. The probabilistic and statistical approaches were used to present the statistical criterion for recognizing classes of objects based on the results of measuring their informative features. These approaches are used to solve optimization problems in statistical theories of identification and recognition. This method allowed the cartographic representing of the change in the water quality and aquatic ecosystem in accordance with the reference areas of the state of the reservoir in 2017.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67116670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dynamic instability of a compound nanocomposite shell","authors":"N. Sakhno, K. Avramov, B. Uspensky","doi":"10.15407/knit2021.05.060","DOIUrl":"https://doi.org/10.15407/knit2021.05.060","url":null,"abstract":"Free oscillations and dynamic instability due to supersonic airflow pressure are investigated in a functional-gradient compound composite conical-cylindrical shell made of a carbon nanotubes-reinforced material. Nanocomposite materials with a linear distribution of the volumetric fraction of nanotubes over the thickness are considered. Extended mixture rule is used to estimate nanocomposite’s mechanical characteristics. A high-order shear deformation theory is used to represent the shell deformation. The assumed-mode technique, along with a Rayleigh-Ritz method, is applied to obtain the equations of the structure motion. To analyze the compound structure dynamics, a new system of piecewise basic functions is suggested. The pressure of a supersonic flow on the shell is obtained by using the piston theory. An example of the dynamic analysis of a nanocomposite conical-cylindrical shell in the supersonic gas flow is considered. The results of its modal analysis using the Rayleigh-Ritz technique are close to the natural frequencies of the shell obtained by finite element analysis. In this case, finite element analysis can only be used for shells made of material with a uniform distribution of nanotubes over the thickness. The dependence of the natural frequencies of a compound shell on the ratio of the lengths of the conical and cylindrical parts is studied. The dependence of the critical pressure of a supersonic flow on the Mach numbers and the type of carbon nanotubes reinforcement is investigated. Shells with a concentration of nanotubes predominantly near the outer and inner surfaces are characterized by higher values of natural frequencies and critical pressure than the shells with a uniform distribution of nanotubes or with a predominant concentration of nanotubes inside the shell.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67117094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Feed-forward control of total retrieval of the space tether from vertical position","authors":"A. Alpatov, C. Wang, A. Zakrzhevskii","doi":"10.15407/knit2021.05.071","DOIUrl":"https://doi.org/10.15407/knit2021.05.071","url":null,"abstract":"This paper presents the results of studies of the feasibility of total and safe retrieval of a space tether of two bodies connected by an elastic, massless cable. The purpose of the research is to build up the control for the mode of the total and safe retrieval of the tether, which is one of the basic modes of its functioning. It allowed the development of the feed-forward control of the tether length or tension that provides demanded change of the angular momentum of the tether under the effect of the gravitational torque. The novelty of the research results consists also in the novel approach to the control of underactuated mechanical systems, which have the number of the control channels less than their degrees of freedom. Here the constraints on the tether angular motion relative to the pitch axis are introduced. They reduce the number of the system degrees of freedom and allow realizing the necessary mode of motion. For this control, only the remaining degree of freedom is used. The numerical simulation of the effect of the mode parameters on the tether motion is carried out for the tether in the chosen ranges of the parameters. The numerical example demonstrates the simplicity of the application of the method in practice. Plots illustrate the analysis of the results.","PeriodicalId":42936,"journal":{"name":"Space Science and Technology-Kosmicna Nauka i Tehnologia","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67117208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}