Ernő Horváth, C. Pozna, P. Kőrös, Csaba Hajdu, Á. Ballagi
Autonomous and self-driving technology is a rapidly emerging field among automotive-related companies and academic research institutes. The main challenges include sensory perception, prediction, trajectory planning and trajectory execution. The current paper introduces a design strategy and the mathematical background of the optimization problem with regard to the multiple goal pure pursuit algorithm. The aim of the algorithm is to provide a low degree of computational complexity and, therefore, a fast trajectory-tracking approach. Finally, in terms of our approach, not only the theoretical questions but the application challenges will be described as well.
{"title":"Theoretical background and application of multiple goal pursuit trajectory follower","authors":"Ernő Horváth, C. Pozna, P. Kőrös, Csaba Hajdu, Á. Ballagi","doi":"10.33927/hjic-2020-03","DOIUrl":"https://doi.org/10.33927/hjic-2020-03","url":null,"abstract":"Autonomous and self-driving technology is a rapidly emerging field among automotive-related companies and academic research institutes. The main challenges include sensory perception, prediction, trajectory planning and trajectory execution. The current paper introduces a design strategy and the mathematical background of the optimization problem with regard to the multiple goal pure pursuit algorithm. The aim of the algorithm is to provide a low degree of computational complexity and, therefore, a fast trajectory-tracking approach. Finally, in terms of our approach, not only the theoretical questions but the application challenges will be described as well.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83425450","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":"Design and Construction of a Vibration Data Acquisition System for Road Vehicles","authors":"R. Nagy, I. Szalai","doi":"10.33927/hjic-2020-11","DOIUrl":"https://doi.org/10.33927/hjic-2020-11","url":null,"abstract":"","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78328450","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}
Power electronics and their control algorithms are very important parts of electric vehicles. The whole system can operate reliably, efficiently and with good dynamics only if all elements of the vehicle are well coordinated. Before the different electric drivetrains can finally be applied, they should be tested under different circumstances on electric motor or drivetrain test benches. Otherwise it would be difficult to test them in-vehicle as they are already built-in. For such testing processes, a flexible test system is a good solution that can be easily modified at both hardware and software levels, especially for institutions like our research center where various types of electric motors from different manufacturers are dealt with. Their inverter systems are usually inaccessible without the help of experts.
{"title":"High-power modular inverter development for electric motor testing purposes","authors":"Zoltán Szeli, G. Szakallas","doi":"10.33927/hjic-2020-04","DOIUrl":"https://doi.org/10.33927/hjic-2020-04","url":null,"abstract":"Power electronics and their control algorithms are very important parts of electric vehicles. The whole system can operate reliably, efficiently and with good dynamics only if all elements of the vehicle are well coordinated. Before the different electric drivetrains can finally be applied, they should be tested under different circumstances on electric motor or drivetrain test benches. Otherwise it would be difficult to test them in-vehicle as they are already built-in. For such testing processes, a flexible test system is a good solution that can be easily modified at both hardware and software levels, especially for institutions like our research center where various types of electric motors from different manufacturers are dealt with. Their inverter systems are usually inaccessible without the help of experts.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79827967","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}
Since the tire pressure has a significant influence on driving safety, even self-driving vehicles need to be aware of their current tire pressures. Two major types of methods for estimating tire pressures exist: direct and indirect methods. In spite of recent advancements in direct Tire Pressure Monitoring Systems (TPMSs), indirect pressure monitoring systems still play a significant role due to their low costs. Indirect systems rely on the processing of signals from wheel speed sensors. In most cases, a transformation is applied to generate a frequency spectrum from which the tire pressure-dependent eigenfrequency can be extracted. The most accurate methods apply the Fourier transform, but these require the highest computational power. After the spectrum of signals from the wheel speed sensor is created, the eigenfrequency must be extracted. Several methods are available to extract significant frequency components. One of the easiest methods is peak searching, however, it is susceptible to noise. On the other hand, more accurate methods that are less sensitive to noise require more computational power. If a transform that consumes less computational power can be applied, then the freed resources can be used by a better eigenfrequency identification method. In this paper, a Hybrid Wavelet-Fourier Transform and Convolutional Neural Network-based method is presented, which exhibits a promising level of noise tolerance.
{"title":"New Hybrid Wavelet and CNN-Based Indirect Tire-Pressure Monitoring System for Autonomous Vehicles","authors":"Zoltán Márton, D. Fodor","doi":"10.33927/hjic-2020-18","DOIUrl":"https://doi.org/10.33927/hjic-2020-18","url":null,"abstract":"Since the tire pressure has a significant influence on driving safety, even self-driving vehicles need to be aware of their current tire pressures. Two major types of methods for estimating tire pressures exist: direct and indirect methods. In spite of recent advancements in direct Tire Pressure Monitoring Systems (TPMSs), indirect pressure monitoring systems still play a significant role due to their low costs. Indirect systems rely on the processing of signals from wheel speed sensors. In most cases, a transformation is applied to generate a frequency spectrum from which the tire pressure-dependent eigenfrequency can be extracted. The most accurate methods apply the Fourier transform, but these require the highest computational power. After the spectrum of signals from the wheel speed sensor is created, the eigenfrequency must be extracted. Several methods are available to extract significant frequency components. One of the easiest methods is peak searching, however, it is susceptible to noise. On the other hand, more accurate methods that are less sensitive to noise require more computational power. If a transform that consumes less computational power can be applied, then the freed resources can be used by a better eigenfrequency identification method. In this paper, a Hybrid Wavelet-Fourier Transform and Convolutional Neural Network-based method is presented, which exhibits a promising level of noise tolerance.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82783585","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}
In the 22nd November 2019 a Workshop was held in the Automotive Proving Ground, Zalaegerszeg, Hungary. The title of Workshop was "Self-Driving Vehicles. Sensors, Algorithms, Intelligent Materials." The Workshop collected experts from the University of Pannonia, Veszprém, and the Széchenyi István University, Győr. The workshop was supported by EFOP-3.6.2-16-2017-00002. The lectures were mostly presented by talented graduate and postgraduate students, who represent future’s professionals. They will be graduated from the two universities and hopefully will seek career in the automotive industry of Hungary, especially, in the industry of slefdriving vehicles. This area of technology is developing fast and strongly supported by governments and various players of the economy due to its potential to drive the development of state-of-the-art technologies. The workshop showed that the research groups working in these two universities can contribute to this development with novel results. This issue of the Hungarian Journal of Industry and Chemistry contains the contributions of the lectures.
{"title":"Editorial Preface to the Special Issue Dedicated to the Workshop Self-Driving Vehicles","authors":"I. Szalai","doi":"10.33927/hjic-2020-01","DOIUrl":"https://doi.org/10.33927/hjic-2020-01","url":null,"abstract":"In the 22nd November 2019 a Workshop was held in the Automotive Proving Ground, Zalaegerszeg, Hungary. The title of Workshop was \"Self-Driving Vehicles. Sensors, Algorithms, Intelligent Materials.\" The Workshop collected experts from the University of Pannonia, Veszprém, and the Széchenyi István University, Győr. The workshop was supported by EFOP-3.6.2-16-2017-00002. The lectures were mostly presented by talented graduate and postgraduate students, who represent future’s professionals. They will be graduated from the two universities and hopefully will seek career in the automotive industry of Hungary, especially, in the industry of slefdriving vehicles. This area of technology is developing fast and strongly supported by governments and various players of the economy due to its potential to drive the development of state-of-the-art technologies. The workshop showed that the research groups working in these two universities can contribute to this development with novel results. This issue of the Hungarian Journal of Industry and Chemistry contains the contributions of the lectures.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90389135","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}
This study reports on the concentration of rutile in the sand recovered from tar sand in Ondo State in Nigeria. The tar-free sand residue, approximately 90 % of which passes through a sieve with a pore size of 355 μm, was subjected to sieve analysis as well as sequences of panning gravity pre-concentration and shaking-table concentration at a slurry density of 25 % solids to improve the rutile content. The sand residue recovered in addition to the panned pre-concentrate and shaking table concentrates were also subjected to reflected light microscopy as well as transmitted light microscopy, counting using ImageJ software and X-ray fluorescence spectroscopy. The micrographs obtained showed that the samples contain rutile, dark-brown in color, interlocked with the major silica content and the content of rutile estimated by ImageJ software increased in the pre-concentrate from 7.90 % to 19.23 % in the final concentrate. X-ray fluorescence spectroscopy also showed that the rutile content increased in the pre-concentrate from 1.43 % to 31.02 % in the final concentrate. Therefore, the rutile content was successfully increased by the cheap gravity techniques of panning and shaking tables.
{"title":"Multistage Gravity Beneficiation of Rutile in a Tar-Free Sand Residue","authors":"R. Akande, A. Adeleke","doi":"10.33927/hjic-2019-17","DOIUrl":"https://doi.org/10.33927/hjic-2019-17","url":null,"abstract":"This study reports on the concentration of rutile in the sand recovered from tar sand in Ondo State in Nigeria. The tar-free sand residue, approximately 90 % of which passes through a sieve with a pore size of 355 μm, was subjected to sieve analysis as well as sequences of panning gravity pre-concentration and shaking-table concentration at a slurry density of 25 % solids to improve the rutile content. The sand residue recovered in addition to the panned pre-concentrate and shaking table concentrates were also subjected to reflected light microscopy as well as transmitted light microscopy, counting using ImageJ software and X-ray fluorescence spectroscopy. The micrographs obtained showed that the samples contain rutile, dark-brown in color, interlocked with the major silica content and the content of rutile estimated by ImageJ software increased in the pre-concentrate from 7.90 % to 19.23 % in the final concentrate. X-ray fluorescence spectroscopy also showed that the rutile content increased in the pre-concentrate from 1.43 % to 31.02 % in the final concentrate. Therefore, the rutile content was successfully increased by the cheap gravity techniques of panning and shaking tables.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80599294","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}
M. Varga, C. Azzaro‐Pantel, José Manuel Flores-Perez, B. Csukás
The planning and operation of Hydrogen Supply Chains (HSC) often require easily extensible, generic dynamic simulation tools. In this paper, the non-conventional modeling and simulation methodology of Programmable Process Structures is applied for the description of these process systems. Programmable Process Structures of HSC models are generated from the two general functional meta-prototypes of the method and from the description of the studied HSC network. The actual program prototypes of production, transformation, transportation, utilization and intermediate storage are copied from the meta-prototypes and filled with the locally executable declarative program code for the various classes of elements. The actual state and transition elements are parameterized and initialized according to their case-specific prototypes. The execution of the programmed HSC structures is solved by the general purpose kernel program. The application of methodology, developed in other fields, is illustrated by a fictitious, simplified HSC example. Analysis of this example model illustrates that the coordination of the hectically changing energy production of renewable resources with its seasonally and tendentiously changing demands is in need of dynamic simulation-based planning.
{"title":"Programmable Process Structure Based Analysis of Hydrogen Supply Chains","authors":"M. Varga, C. Azzaro‐Pantel, José Manuel Flores-Perez, B. Csukás","doi":"10.33927/hjic-2019-20","DOIUrl":"https://doi.org/10.33927/hjic-2019-20","url":null,"abstract":"The planning and operation of Hydrogen Supply Chains (HSC) often require easily extensible, generic dynamic simulation tools. In this paper, the non-conventional modeling and simulation methodology of Programmable Process Structures is applied for the description of these process systems. Programmable Process Structures of HSC models are generated from the two general functional meta-prototypes of the method and from the description of the studied HSC network. The actual program prototypes of production, transformation, transportation, utilization and intermediate storage are copied from the meta-prototypes and filled with the locally executable declarative program code for the various classes of elements. The actual state and transition elements are parameterized and initialized according to their case-specific prototypes. The execution of the programmed HSC structures is solved by the general purpose kernel program. The application of methodology, developed in other fields, is illustrated by a fictitious, simplified HSC example. Analysis of this example model illustrates that the coordination of the hectically changing energy production of renewable resources with its seasonally and tendentiously changing demands is in need of dynamic simulation-based planning.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76785565","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}
The rotary valve is the most frequently used piece of equipment that is suitable for the controlled feeding or discharging of products in powdered or granular form. It is usually connected to silos, hoppers, pneumatic conveying systems, bag filters or cyclones. In this paper, a simulation study is presented on the discharge of solid particles from a silo through a rotary valve. The discrete element method (DEM), which accounts for collisions between particles and particle-wall collisions, was used to model and simulate the motion of individual particles. The diameter of the simulated silo was 0.2 m and a total of 245,000 particles were calculated. In the simulations, the effect of the geometric and operational parameters of the rotary valve on the mass outflow rate was investigated. The diameter of the rotary valve varied between 0.06 and 0.12 m and the rotational speed of the rotor was changed between 0.5 and 5 1 . The simulations showed that the mass outflow rate of the particles from the rotary valve changes periodically due to its rotary cell structure. Within the lower range of rotational speeds of the rotor, the mass outflow rate of particles changes linearly in correlation with the rotational speed. The identification of this linear section is important in terms of control as this would facilitate the implementation of control devices by applying well-established linear control algorithms. Adjacent to the linear section, the dependence of the average mass outflow rate on the rotational speed was found to be nonlinear. Within the upper range of examined rotational speeds for each diameter of the rotary valve, the mass outflow rate reaches a maximum then decreases. The simulations were performed using GPU hardware. The application of parallel programming was an essential aspect of the simulations and significantly decreased the calculation time of simulations. In the treatment of particle-wall contacts, a novel flat triangular-based geometric representation technique was used which allows the particle-wall contacts to be calculated more effectively and their treatment implemented more easily into the parallel programming code. Using the calculated particle positions, the particles were visualized to view the effect of the interactions between the particles and rotor blades on particle motion. The simulation results showed that the discrete element method is capable of determining the detailed flow patterns of particles through the rotary valve at various rotational speeds.
{"title":"GPU-Accelerated Simulation of a Rotary Valve by the Discrete Element Method","authors":"Balázs Füvesi, Z. Ulbert","doi":"10.33927/hjic-2019-18","DOIUrl":"https://doi.org/10.33927/hjic-2019-18","url":null,"abstract":"The rotary valve is the most frequently used piece of equipment that is suitable for the controlled feeding or discharging of products in powdered or granular form. It is usually connected to silos, hoppers, pneumatic conveying systems, bag filters or cyclones. In this paper, a simulation study is presented on the discharge of solid particles from a silo through a rotary valve. The discrete element method (DEM), which accounts for collisions between particles and particle-wall collisions, was used to model and simulate the motion of individual particles. The diameter of the simulated silo was 0.2 m and a total of 245,000 particles were calculated. In the simulations, the effect of the geometric and operational parameters of the rotary valve on the mass outflow rate was investigated. The diameter of the rotary valve varied between 0.06 and 0.12 m and the rotational speed of the rotor was changed between 0.5 and 5 1 . The simulations showed that the mass outflow rate of the particles from the rotary valve changes periodically due to its rotary cell structure. Within the lower range of rotational speeds of the rotor, the mass outflow rate of particles changes linearly in correlation with the rotational speed. The identification of this linear section is important in terms of control as this would facilitate the implementation of control devices by applying well-established linear control algorithms. Adjacent to the linear section, the dependence of the average mass outflow rate on the rotational speed was found to be nonlinear. Within the upper range of examined rotational speeds for each diameter of the rotary valve, the mass outflow rate reaches a maximum then decreases. The simulations were performed using GPU hardware. The application of parallel programming was an essential aspect of the simulations and significantly decreased the calculation time of simulations. In the treatment of particle-wall contacts, a novel flat triangular-based geometric representation technique was used which allows the particle-wall contacts to be calculated more effectively and their treatment implemented more easily into the parallel programming code. Using the calculated particle positions, the particles were visualized to view the effect of the interactions between the particles and rotor blades on particle motion. The simulation results showed that the discrete element method is capable of determining the detailed flow patterns of particles through the rotary valve at various rotational speeds.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85153046","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}
N. Kováts, B. Eck-Varanka, Zsófia Békéssy, D. Diósi, K. Hubai, János Korponai
{"title":"Assessment of the Ecotoxicity of Nanoplastics","authors":"N. Kováts, B. Eck-Varanka, Zsófia Békéssy, D. Diósi, K. Hubai, János Korponai","doi":"10.33927/hjic-2019-22","DOIUrl":"https://doi.org/10.33927/hjic-2019-22","url":null,"abstract":"","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76795929","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}
Mixing is one of the most crucial processes in the chemical industry. Homogeneity is a requirement for all feedstocks and industrial products. The degree of mixing depends on the hydrodynamic properties of the fluid in the units. The Residence Time Distribution (RTD) was investigated in a tank of a special geometry. Mixing was investigated using various geometries of the tank by applying the Heaviside function in step-response experiments. After obtaining experimental results, the RTD function was calculated. The flow structure in the tank was approximated by fitting black-box transfer function models onto the RTD function of the system. Two general model structures were defined and their fitness compared. By evaluating the fitted models, a relationship was established between the flow structure in the tank and its geometry.
{"title":"Investigation of Mixing in Tanks of a Special Geometry","authors":"B. Tarcsay, A. Egedy, J. Bobek, Dóra Rippel-Pethő","doi":"10.33927/hjic-2019-21","DOIUrl":"https://doi.org/10.33927/hjic-2019-21","url":null,"abstract":"Mixing is one of the most crucial processes in the chemical industry. Homogeneity is a requirement for all feedstocks and industrial products. The degree of mixing depends on the hydrodynamic properties of the fluid in the units. The Residence Time Distribution (RTD) was investigated in a tank of a special geometry. Mixing was investigated using various geometries of the tank by applying the Heaviside function in step-response experiments. After obtaining experimental results, the RTD function was calculated. The flow structure in the tank was approximated by fitting black-box transfer function models onto the RTD function of the system. Two general model structures were defined and their fitness compared. By evaluating the fitted models, a relationship was established between the flow structure in the tank and its geometry.","PeriodicalId":13010,"journal":{"name":"Hungarian Journal of Industrial Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77645474","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}
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