Journal of the Russian Universities. Radioelectronics最新文献

{"title":"Contribution of the Scientific School of Saint Petersburg Electrotechnical University in the Field of Optimal Discrete Signal Design","authors":"V. P. Ipatov","doi":"10.32603/1993-8985-2023-26-5-6-20","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-5-6-20","url":null,"abstract":"Introduction. Numerous modern infocommunication systems are based on the spread spectrum technology, i. e., on the use of signals with a large bandwidth-duration product. Many such systems implement discrete signals, which are sequences of standard pulses manipulated in phase and amplitude. The design of code sequences for such signals is a fairly knowledge-intensive task requiring a serious mathematical apparatus. This review presents the results of Saint Petersburg Electrotechnical University school in the field of synthesis of code sequences with ideal or nearly ideal autocorrelation, as well as code ensembles for CDMA networks.   Aim. To acquaint the reader with the results of long-term research carried out by Saint Petersburg Electrotechnical University school in the field of discrete signal design.   Materials and methods. The materials under review included the publications of specialists from the Radio System Department of Saint Petersburg Electrotechnical University and those published by domestic and foreign researchers on the corresponding topics. The major focus was to review the most theoretically significant texts published in leading domestic and foreign journals over the past four decades, leaving applied studies, copyright certificates and patents outside the scope of the review. At the same time, the review included those foreign publications of applied nature that are significant for the development of information and communication projects.   Results. The reviewed publications significantly expand the range of discrete signals that are promising for wireless infocommunication applications.   Conclusion. Solutions of a number of the studied topical problems to design sequences with the necessary metric properties are of an original nature and great practical importance.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139229226","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":"Analytical Models for the Time Response of a Microstrip Line with Two Additional Symmetrical Conductors on Top under Different Boundary Conditions at Their Ends","authors":"A. Sekenova, Z. Kenzhegulova, I. Y. Sagiyeva, T. Gazizov","doi":"10.32603/1993-8985-2023-26-5-21-30","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-5-21-30","url":null,"abstract":"Introduction. Protection of radio electronic equipment (REA) against various electromagnetic interferences is an important aspect of electromagnetic capability. Among interferences for REA, ultra-short pulses of picosecond and nanosecond ranges represent the highest danger due to their high voltage, short duration, and wide spectrum. One effective protection measure consists in the use of bandpass devices based on modal decomposition, such as modal filters (MF). This requires an analysis of distortion of the temporal response of bandpass devices, which is usually carried out numerically. However, even for simple configurations, this approach is associated with high computational costs. Yet simple analytical time-response models are acceptable in some cases. In the initial design stages, such models are extremely useful in providing a preliminary solution and a rapid assessment of response distortions. Therefore, comparison of time responses obtained by numerical methods and analytical models appears an important research task.   Aim. To compare the time responses obtained by quasi-static analysis and analytical models.   Materials and methods. Analytical models for computing time responses based on a modal analysis technique were considered. A quasi-static modeling of a microstrip line (MSL) with two additional symmetrical conductors on top in the TALGAT system was carried out.   Results. Analytical models are proposed for an MSL with two additional symmetrical conductors on top taking different boundary conditions at their ends into account. The accuracy and reliability of the proposed models are verified by comparing the time responses obtained by quasi-static analysis and the proposed models. The results obtained showed good agreement.   Conclusion. It is shown that an MSL with two additional symmetrical conductors on top can be used as an MF under different boundary conditions at the ends of these conductors. The proposed models allow the shape and amplitude of the response to be estimated with acceptable accuracy, reducing time and computational costs.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"253 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139228112","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":"Flexible Approximation Functions: Resonant Loads","authors":"G. A. Filippovich, M. A. Yantsevich","doi":"10.32603/1993-8985-2023-26-5-31-39","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-5-31-39","url":null,"abstract":"Introduction. Patch antennas have found wide application in UAVs due to their numerous useful properties. However, since such an antenna system is essentially a resonator, the problem of its matching remains unresolved. The existing publications mostly deal with specific cases and report the typical values of the matching band of 5–7 %, which cannot be considered sufficient when there is a need to use the signal spectrum of up to hundreds of MHz. Therefore, research aimed at using more efficient methods of broadband matching could be of interest for engineers.   Aim. To develop a broadband matching technique based on the generalized Darlington synthesis method using flexible approximating functions (AF) for load models with resonant properties.   Materials and methods. The capabilities of the generalized Darlington synthesis method are extended AFs with increased variation properties. Flexible control of AF weight coefficients makes it possible to realize both smooth and wave frequency characteristics. The method is analytical and does not use iterative procedures. The mathematical apparatus of the method is based on an analysis of deductions in the zeros of the load resistance transfer function.   Results. Flexible approximating functions were established to be effective for synthesis of matching circuits with resonant properties. Solutions for matching the loads with multiple transfer zeros both at the origin and in infinity were obtained. The opportunity of creating patch antennas with a matching layer up to 40 % and more was demonstrated.   Conclusion. The results obtained for the SWR of patch antennas show that the potential estimates of matching limits are available only for analytical methods.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139235078","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":"Verifying Measurements of Surface Current Velocities by X-Band Coherent Radar Using Drifter Data","authors":"I. G. Gorbunov, V. Veremyev, Vadim D. Shestak, G. V. Komarov, S. Myslenkov, K. Silvestrova","doi":"10.32603/1993-8985-2023-26-3-99-110","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-3-99-110","url":null,"abstract":"Introduction. Conventional contact measurements of hydrographic parameters frequently fail to provide the necessary accuracy of data in the field of water area monitoring. This problem can be solved using coherent radars enabling direct measurements of surface current velocities.Aim. To establish the accuracy of surface current velocities measured by a Doppler radar using drifter data.Materials and methods. In June 2022, coastal operational oceanography studies were conducted at the hydrophysical test site of the Institute of Oceanology of the Russian Academy of Sciences in the Black Sea near Gelendzhik. Measurements were carried out using a coherent X-band radar installed on the Ashamba research vessel simultaneously with drifter experiments using Lagrangian drifters of the near-surface layer with an underwater 0.5 m sail. Coordinates were transmitted via mobile communication. The drifter data on the current velocity and direction were used to verify radar measurements. Measurements were taken onboard of the research vessel at a low speed and different distances from the shore, near the drifters. The tracks of the vessel and drifters were recorded simultaneously. Processing of the radar data involved obtaining Doppler spectra of signals to estimate the dynamic processes on the sea surface, including the current velocity.Results. Radial components of the near-surface current velocity were calculated. Then, the current velocity values obtained based on the drifter and radar data were compared.Conclusion. The present work makes a contribution to the advancement of methods for measuring surface currents from the board of a moving ship by Doppler radars. The obtained results confirm the suitability of the radar hardware and software and signal processing algorithms for measuring currents. The radar measurement data were found agree well with drifter data in the velocity range from 15 cm/s.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123668422","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":"Diagnostics of Atmospheric Plasma Jets of Helium and Argon Barrier Discharge in a Cylindrical Microwave Cavity Resonator","authors":"A. Astafiev, A. Altmark, N. Lesiv, A. Chirtsov","doi":"10.32603/1993-8985-2023-26-3-122-135","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-3-122-135","url":null,"abstract":"Introduction. Technologies related to the use of low-temperature atmospheric plasmas are developing at a rapid pace. Creation of new low-temperature plasma sources for specific applications requires monitoring of dynamic processes in such discharges with a high time resolution. Electron concentration is one the most important plasma characteristics, which can be very low for a low-temperature atmospheric pressure plasma. However, the methods currently available for diagnostics of gas-discharge plasmas are either characterized by insufficient sensitivity or unable to monitor dynamic processes in non-stationary discharges. In this regard, the development of new diagnostic approaches to low-temperature atmospheric plasma seems to be a relevant research direction.Aim. To develop a diagnostic method for an atmospheric plasma with a low gas temperature and a low electron concentration in a cylindrical microwave resonator.Materials and methods. The proposed diagnostic method is based on the well-known principle of measuring the frequency shift and the Q-factor of the eigenmodes of the microwave resonator, inside which the plasma under study is located.Results. Measurements of the atmospheric barrier discharge plasma jets in a helium and argon stream in a cylindrical microwave resonator were performed. The proposed geometry made it possible to significantly increase the sensitivity of measurements. It became possible to exclude the effect of polarization degeneracy in a round cylindrical resonator. The developed system was also tested on test objects with a known value of permittivity.Conclusion. A method for microwave diagnostics of stationary and non-stationary cold atmospheric plasma jets in a cylindrical resonator, inside which transmitting and receiving antennas are installed, as well as an orthogonal thin conductor preventing the excitation of undesirable modes, was developed.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125707180","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":"Electrocaloric Effect in Multilayer Ferroelectric Structures","authors":"A. Starkov, A. Anokhin, A. Es'kov, A. A. Semenov, A. Kholkin","doi":"10.32603/1993-8985-2023-26-3-111-121","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-3-111-121","url":null,"abstract":"Introduction. Ferroelectric films are widely used for radiotechnical, microwave microelectronic, sensoric, and energy conversion purposes. Such a diverse application range demands film materials with specific electrophysical properties. For instance, while energy storage applications require materials with a high dielectric constant, energy conversion devices largely use those with a low dielectric constant. The necessary physical properties can be achieved using multicomponent ferroelectric structures, such as solid solutions, composites, and multilayer film structures. Mechanical stresses between the substrate and ferroelectric layers play an extremely important role in dielectric properties of multilayer structures.Aim. Development of a mathematical model quantifying the ferroelectric polarization, static dielectric constant, as well as pyroelectric and electrocaloric properties of multilayered ferroelectric film structures.Materials and methods. The presented model is based on the Landau–Ginzburg–Devonshire model (LGD) considering elasticity equations and using electric induction as the order parameter.Results. The developed mathematical model based on LGD provides for a quantifiable description of dielectric, pyroelectric, and electrocaloric properties of layered ferroelectric structures. This model displays the effect of the thickness ratio of polycrystalline layers and grain size distribution on the dielectric properties of films.Conclusion. The developed quantitative model demonstrates the dependence of the thickness, grain size, and stacking order of ferroelectric layers on the dielectric constant and pyroelectric coefficient of multilayered polycrystalline film structures. The presented model can be applied when optimizing the parameters of multilayer structures with respect to their application area.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130678700","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":"A Target Threat Assessment Method for Application in Air Defense Command and Control Systems","authors":"X. Nguyen, Kim Phuong Phung, Quang Hieu Dang, Xung Ha Vo, Hoa Tien Vu","doi":"10.32603/1993-8985-2023-26-3-90-98","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-3-90-98","url":null,"abstract":"Introduction. This paper presents a solution for threat assessment of air targets using the fuzzy logic inference method. The approach is based on the Sugeno fuzzy model, which has multiple inputs representing target trajectory parameters and a single output representing the target threat value. A set of IF–THEN fuzzy inference rules, utilizing the AND operator, is developed to assess the input information.Aim. To develop and test an algorithm model to calculate the threat value of an air target for use in real-time automated command and control systems.Materials and methods. An algorithm model was developed using a fuzzy model to calculate the threat value of a target. The model is presented in the form of a flowchart supported by a detailed stepwise implementation process. The accuracy of the proposed algorithm was evaluated using the available toolkit in MATLAB. Additionally, a BATE software testbed was developed to assess the applicability of the algorithm model in a real-time automated command and control system.Results. The efficiency of the proposed fuzzy model was evaluated by its simulation and testing using MATLAB tools on a set of 10 target trajectories with different parameters. Additionally, the BATE software was utilized to test the model under various air defense scenarios. The proposed fuzzy model was found to be capable of efficiently computing the threat value of each target with respect to the protected object.Conclusion. The proposed fuzzy model can be applied when developing tactical supporting software modules for real-time air defense command and control systems.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115481303","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":"Creation of a Vivaldi-Based Circular Antenna Array for Broadband Relay Channels","authors":"Pavel A. Mezhevov, K. Korovin, Aleksey N. Likontsev","doi":"10.32603/1993-8985-2023-26-3-58-66","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-3-58-66","url":null,"abstract":"Introduction. Unmanned aerial vehicles (UAVs) are rapidly gaining in popularity. The UVA development requires active antenna systems capable of forming a narrow beam of the main lobe of the radiation pattern. Although numerous studies have considered specialized antenna arrays with a wide range of scanning angles, the location of such systems on UAVs remains under-investigated. The development of such arrays for UAVs will enable the creation of a secure relay broadband channel with a few repeaters.Aim. Development of a broadband antenna array for UAVs with the possibility of setting the main lobe of the radiation pattern in any direction of the azimuthal plane, for use in relay tasks.Materials and methods. An emitter model and a circular antenna array on its basis was developed in the Ansys HFSS electromagnetic modeling package.Results. The dependence of the directional coefficient and the gain for an array consisting of 8 and 16 elements was shown. Voltage standing-wave ratio dependences and directivity patterns that satisfy the conditions of retransmission in a wide-frequency band using UAVs were obtained. Recommendations on the number of active elements in a circular antenna array that ensure the maximum gain (directivity) were formulated.Conclusion. Technical solutions that can be used in the development of UAVs are proposed. The system can be further improved by optimizing the antenna array elements and using a cylindrical or hemispherical array.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132588963","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":"Nonparametric Bayesian Networks as a Tool of Multiscale Time Series Analysis and Remote Sensing Data Integration","authors":"N. Pyko, D. Tishin, Pavel Y. Iskandirov, A. Gafurov, B. Usmanov, M. Bogachev","doi":"10.32603/1993-8985-2023-26-3-32-37","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-3-32-37","url":null,"abstract":"Introduction. Nonparametric Bayesian networks are a promising tool for analyzing, visualizing, interpreting and predicting the structural and dynamic characteristics of complex systems. Modern interdisciplinary research involves the complex processing of heterogeneous data obtained using sensors of various physical nature. In the study of the forest fund, both methods of direct dendrological measurements and methods of remote observation using unmanned aerial vehicles are widely used. Information obtained using these methods must be analyzed in conjunction with hydrometeorological monitoring data.Aim. Investigation of the possibility of automating the monitoring of the well-being of the forest fund based on the integration of ground survey data, remote multispectral measurements and hydrometeorological observations using the mathematical apparatus of nonparametric Bayesian networks.Materials and methods. To assess the long-term joint dynamics of natural and climatic indicators and the radial growth of trees, a modified method of multiscale cross-correlation analysis was used with the removal of the background trend described by the moving average model. Relationships between various indicators were estimated based on the unconditional and conditional nonparametric Spearman correlation coefficients, which were used to reconstruct and parameterize the nonparametric Bayesian network.Results. A multiscale nonparametric Bayesian network was constructed to characterize both unconditional and conditional statistical relationships between parameters obtained from remote sensing, hydroclimatic and dendrological measurements. The proposed model showed a good quality of the plant fund state forecasting. The correlation coefficients between the observed and predicted indicators exceed 0.6, with the correlation coefficient comprising 0.77 when predicting the growth trend of annual tree rings.Conclusion. The proposed nonparametric Bayesian network model reflects the relationship between various factors that affect the forest ecosystem. The Bayesian network can be used to assess risks and improve environmental management planning.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131231047","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":"Simulation of a Radio Signal Scattered from a Rough Surface by the Method of Stationary Points","authors":"Andrey A. Monakov","doi":"10.32603/1993-8985-2023-26-3-67-76","DOIUrl":"https://doi.org/10.32603/1993-8985-2023-26-3-67-76","url":null,"abstract":"Introduction. Many radar and radio navigation problems require adequate (i.e., corresponding to the physics of radio wave scattering under a certain set of conditions) simulation of a radio signal scattered from a rough surface. At present, four categories of mathematical models are used for these purposes, with each corresponding to a particular group of methods for solving the scattering problem. These methods include those based on a rigorous solution of the electrodynamic equations (methods of moments, finite elements, finite differences); approximate methods for solving electrodynamic problems (methods of small perturbations, tangent plane (Kirchhoff method), two-scale model); those of statistical equivalents; and phenomenological models. In the former two categories, the electromagnetic field is computed on a surface grid, whose step must be much smaller than the signal wavelength. This makes the simulation of a scattered radio signal effectively unrealizable for two-dimensional rough surfaces. The method of statistical equivalents is based on the calculation of the probabilistic characteristics of a scattered signal. Difficulties arising in this case narrow the possibilities of simulation, largely due to the impossibility of obtaining closed expressions for the required characteristics without significant simplifications. In addition, carrying out analytical calculations, the solution is restricted to the class of surfaces with the Gaussian distribution of roughness heights. Phenomenological models, although providing for a qualitative analysis of signal scattering from a rough surface, fail to take the physics of the scattering process into account.Aim. To create a simple and adequate model of a signal scattered from a two-dimensional rough surface using the tangent plane approximation of the boundary conditions (the Kirchhoff method), which can be realized on modern computers.Materials and methods. The proposed model of the scattered signal is based on its representation as a sum of signals reflected from stationary points on the surface, i.e., those points where the law of specular reflection of the incident electromagnetic wave is locally fulfilled.Results. The implementation of the model is reduced to determination of the positions of stationary points on a twodimensional rough surface. This problem is solved on modern computers quite simply without computations with complex numbers. It turns out that the number of stationary points, even with a large surface roughness, rarely exceeds two. This fact, along with the simplicity of finding the coordinates of stationary points, makes this model suitable for long series of statistical runs.Conclusion. The proposed model is easy to implement and can be used to study the accuracy of low-altitude target estimation, altimeters, Doppler and correlation speed and drift angle estimators.","PeriodicalId":217555,"journal":{"name":"Journal of the Russian Universities. Radioelectronics","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116803345","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}