Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811752
B. Sen, Ren Kailin, Romika Sharma, Jayantika Soni, S. K. Panda
Electric spring is a new smart grid technology which can regulate voltage fluctuations caused due to integration of intermittent renewable energy sources. So far electric springs have been studied mostly with resistive loads which are ON all the time. This paper analyses the performance of electric spring when connected with different types of variable loads. The electric spring circuit was simulated in MATLAB/Simulink environment with three types of loads — resistive, resistive-inductive and resistive-capacitive. The circuit was modified such that some of the loads are OFF for a certain part of the simulation. The effect of load variation on the performance of electric spring did not vary with the type of load. However, the change in stress on electric spring with load variation depends on the type of load attached to it. A detailed analysis has been provided in the paper.
{"title":"Performance evaluation of electric spring: Effect of load variation on voltage regulation","authors":"B. Sen, Ren Kailin, Romika Sharma, Jayantika Soni, S. K. Panda","doi":"10.1109/ICSET.2016.7811752","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811752","url":null,"abstract":"Electric spring is a new smart grid technology which can regulate voltage fluctuations caused due to integration of intermittent renewable energy sources. So far electric springs have been studied mostly with resistive loads which are ON all the time. This paper analyses the performance of electric spring when connected with different types of variable loads. The electric spring circuit was simulated in MATLAB/Simulink environment with three types of loads — resistive, resistive-inductive and resistive-capacitive. The circuit was modified such that some of the loads are OFF for a certain part of the simulation. The effect of load variation on the performance of electric spring did not vary with the type of load. However, the change in stress on electric spring with load variation depends on the type of load attached to it. A detailed analysis has been provided in the paper.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123574304","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811776
Aysun Koksal, A. Ozdemir
The competitive electricity market requires that the high maintenance costs are decreased and the maintenance efficiency are increased as well as the asset life time. The maintenance planning based on the reliability centered maintenance (RCAM) concept for electric transmission system aims to maximize the system reliability with reasonable costs. This study is the extension of recent RCAM based improved transformer maintenance procedure and constructed Asset Management (AM) plan and presents a verification method for this procedure and AM plan. The proposed procedure is applied to the power transformers located at the Thrace Region of Turkish National Power Transmission System.
{"title":"RCAM based asset management study for Turkish National Power Transmission System: Verification stage","authors":"Aysun Koksal, A. Ozdemir","doi":"10.1109/ICSET.2016.7811776","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811776","url":null,"abstract":"The competitive electricity market requires that the high maintenance costs are decreased and the maintenance efficiency are increased as well as the asset life time. The maintenance planning based on the reliability centered maintenance (RCAM) concept for electric transmission system aims to maximize the system reliability with reasonable costs. This study is the extension of recent RCAM based improved transformer maintenance procedure and constructed Asset Management (AM) plan and presents a verification method for this procedure and AM plan. The proposed procedure is applied to the power transformers located at the Thrace Region of Turkish National Power Transmission System.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"148 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116551212","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811808
Bui Minh Dinh, Honghao Tien
Line start permanent magnet synchronous motor (LSPMSM) is one of the highest efficiency motors due to no rotor copper loss at synchronous speed and self starting. LSPMSM has torque characteristics of both induction motor IM and Permanent Magnet Synchronous Motor-PMSM. In order to maximize efficiency, an optimal design method of cage-bars and magnet shape has to be considered [1]. The geometry parameters of stator and rotor can be obtained by an analytical model method [2] and validated by FEM simulation. This paper describes a comprehensive design of a three phase LPMSM motor 7.5 kW for electrical drive application. A maximum efficiency design of LPMSM will be implemented by both analytical and FEM methods.
{"title":"Maximum efficiency design of line start permanent magnet synchronous motor","authors":"Bui Minh Dinh, Honghao Tien","doi":"10.1109/ICSET.2016.7811808","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811808","url":null,"abstract":"Line start permanent magnet synchronous motor (LSPMSM) is one of the highest efficiency motors due to no rotor copper loss at synchronous speed and self starting. LSPMSM has torque characteristics of both induction motor IM and Permanent Magnet Synchronous Motor-PMSM. In order to maximize efficiency, an optimal design method of cage-bars and magnet shape has to be considered [1]. The geometry parameters of stator and rotor can be obtained by an analytical model method [2] and validated by FEM simulation. This paper describes a comprehensive design of a three phase LPMSM motor 7.5 kW for electrical drive application. A maximum efficiency design of LPMSM will be implemented by both analytical and FEM methods.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123961720","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811769
T. Tran
Recently, The World is being challenged by energy crisis and global climate changing. By this reasons, it is necessary to give the methods so as to gain the development and utilization of renewable energy, improve energy structure, ensure energy security, protect environment, and achieve sustainable economic and social development. This article concentrates on researching of the biomass densification technology by analyzing technical economy of large scale application depending on Fuzzy synthetic evaluation methodology creates Weaver — Thomas model with the aim of reducing the Greenhouse Gases Emission.
{"title":"A research of large-scale biomass densification technology in order to reduce the greenhouse gases emission","authors":"T. Tran","doi":"10.1109/ICSET.2016.7811769","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811769","url":null,"abstract":"Recently, The World is being challenged by energy crisis and global climate changing. By this reasons, it is necessary to give the methods so as to gain the development and utilization of renewable energy, improve energy structure, ensure energy security, protect environment, and achieve sustainable economic and social development. This article concentrates on researching of the biomass densification technology by analyzing technical economy of large scale application depending on Fuzzy synthetic evaluation methodology creates Weaver — Thomas model with the aim of reducing the Greenhouse Gases Emission.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125195855","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811807
Woranunt Lao-atiman, Suphatcha Chiraphatphimon, N. Sinbuathong, C. Jeraputra, Chularat Sakdaronnarong
Industrial wastewater pretreatment through the anaerobic digestion is able to generate both biogas and electricity in microbial fuel cells (MFCs). In this work, hydrogen was produced in MFC combining rice vermicelli wastewater treatment using enriched hydrogen producing consortia. Effects of sludge pretreatment and addition of supplements, mediator (lignin) and glucose were studied to determine the optimum condition for the operation in MFC. The results showed that the pretreatment of sludge inhibited methanogenesis and higher content of hydrogen gas was substantially produced. Adding glucose and lignin was found to facilitate hydrogen production (50.2%). In MFC, pretreated sludge was able to produce more fermentative hydrogen, higher COD removal and solid removal, nevertheless generated electricity was reduced compared with untreated sludge. An increase of amount of granular activated carbon (GAC) used as anode from 700 to 1200 g considerably enhanced hydrogen production from 20.02 to 73.25 % (115 to 926 mL), increased power density from 11.92 to 20.33 mW/m2 (at 750A) and increased COD removal from 45.45 to 57.14%.
{"title":"Hydrogen and electricity production from anaerobic digestion of rice vermicelli wastewater by mixed acidophilic consortia in a microbial fuel cell","authors":"Woranunt Lao-atiman, Suphatcha Chiraphatphimon, N. Sinbuathong, C. Jeraputra, Chularat Sakdaronnarong","doi":"10.1109/ICSET.2016.7811807","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811807","url":null,"abstract":"Industrial wastewater pretreatment through the anaerobic digestion is able to generate both biogas and electricity in microbial fuel cells (MFCs). In this work, hydrogen was produced in MFC combining rice vermicelli wastewater treatment using enriched hydrogen producing consortia. Effects of sludge pretreatment and addition of supplements, mediator (lignin) and glucose were studied to determine the optimum condition for the operation in MFC. The results showed that the pretreatment of sludge inhibited methanogenesis and higher content of hydrogen gas was substantially produced. Adding glucose and lignin was found to facilitate hydrogen production (50.2%). In MFC, pretreated sludge was able to produce more fermentative hydrogen, higher COD removal and solid removal, nevertheless generated electricity was reduced compared with untreated sludge. An increase of amount of granular activated carbon (GAC) used as anode from 700 to 1200 g considerably enhanced hydrogen production from 20.02 to 73.25 % (115 to 926 mL), increased power density from 11.92 to 20.33 mW/m2 (at 750A) and increased COD removal from 45.45 to 57.14%.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125237187","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811794
H. Le, J. Itoh
This paper proposes a Discontinuous current mode (DCM) feedback current control for the grid-connected inverter in order to achieve the low THD of the grid current at wide load range. In the DCM operation, the nonlinearity between the duty ratio and the current occurs in the current command response, whereas another nonlinearity between the disturbance voltage and the current occurs in the disturbance response. Therefore, the nonlinearity in the current command response is compensated by utilizing the duty ratio at the previous calculation period, whereas the nonlinearity in the disturbance response is utilized in order to reduce the effect of the disturbance and improve the grid current THD at light load. As a result, the grid current THD of the proposed DCM feedback current control is reduced by 89.0% at light load of 0.1 p.u. compared to the conventional Continuous current mode (CCM) feedback current control. Furthermore, the smooth current regulation is confirmed even when the load step change occurs from 1.0 p.u. to 0.1 p.u.
{"title":"Current THD reduction for grid-connected inverter operating in discontinuous current mode","authors":"H. Le, J. Itoh","doi":"10.1109/ICSET.2016.7811794","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811794","url":null,"abstract":"This paper proposes a Discontinuous current mode (DCM) feedback current control for the grid-connected inverter in order to achieve the low THD of the grid current at wide load range. In the DCM operation, the nonlinearity between the duty ratio and the current occurs in the current command response, whereas another nonlinearity between the disturbance voltage and the current occurs in the disturbance response. Therefore, the nonlinearity in the current command response is compensated by utilizing the duty ratio at the previous calculation period, whereas the nonlinearity in the disturbance response is utilized in order to reduce the effect of the disturbance and improve the grid current THD at light load. As a result, the grid current THD of the proposed DCM feedback current control is reduced by 89.0% at light load of 0.1 p.u. compared to the conventional Continuous current mode (CCM) feedback current control. Furthermore, the smooth current regulation is confirmed even when the load step change occurs from 1.0 p.u. to 0.1 p.u.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130675649","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811785
Weiping Zhang, P. Mao, Jie Li
In this paper, the dynamics of the half-bridge LLC resonant converter are investigated based on the small signal model and a piecewise PI regulation is studied and derived by simulation. Small-signal dynamics of the circuit under consideration contain many factors that may affect regulation accuracy and performance of digitally controlled regulators. The load factor is specifically addressed here. The objective of this paper is to introduce a digital piecewise PI compensation to achieve time-optimal response to an external disturbance such as a step load transient.
{"title":"The analysis of piecewise PI compensation based on the digital control of half-bridge LLC","authors":"Weiping Zhang, P. Mao, Jie Li","doi":"10.1109/ICSET.2016.7811785","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811785","url":null,"abstract":"In this paper, the dynamics of the half-bridge LLC resonant converter are investigated based on the small signal model and a piecewise PI regulation is studied and derived by simulation. Small-signal dynamics of the circuit under consideration contain many factors that may affect regulation accuracy and performance of digitally controlled regulators. The load factor is specifically addressed here. The objective of this paper is to introduce a digital piecewise PI compensation to achieve time-optimal response to an external disturbance such as a step load transient.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130969747","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811784
Taichiro Sakagami, Y. Asai, H. Kitano
In December, 2014, we installed a DC microgrid system in the campus village at the Okinawa Institute of Science and Technology and the system has been operational continuously for the past 16 months. This microgrid system was designed to exchange energy among houses using DC so as to utilize surplus energy before the rechargeable batteries reach full capacity. Data obtained in this real environment were used to create a simulator that enabled us to determine the optimal configuration of this microgrid based on current PV and battery costs and predicted future costs. The simulation shows optimal structure of this DC microgrid is 4.6 kW PVs and 3.6 kWh battery per house with total installation costs of 0.5 M US$. In the future it should be possible to reduce installation costs based on the predicted PV and batteries price. Cost recovery period should be reduced by 42% while achieving the self-sufficiency ratio of the present DC microgrid. More PVs and batteries are installed, the recovery period will diminish further still.
{"title":"Simulation to optimize a DC microgrid in Okinawa","authors":"Taichiro Sakagami, Y. Asai, H. Kitano","doi":"10.1109/ICSET.2016.7811784","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811784","url":null,"abstract":"In December, 2014, we installed a DC microgrid system in the campus village at the Okinawa Institute of Science and Technology and the system has been operational continuously for the past 16 months. This microgrid system was designed to exchange energy among houses using DC so as to utilize surplus energy before the rechargeable batteries reach full capacity. Data obtained in this real environment were used to create a simulator that enabled us to determine the optimal configuration of this microgrid based on current PV and battery costs and predicted future costs. The simulation shows optimal structure of this DC microgrid is 4.6 kW PVs and 3.6 kWh battery per house with total installation costs of 0.5 M US$. In the future it should be possible to reduce installation costs based on the predicted PV and batteries price. Cost recovery period should be reduced by 42% while achieving the self-sufficiency ratio of the present DC microgrid. More PVs and batteries are installed, the recovery period will diminish further still.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133950832","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811748
T. Vu, K. Turitsyn
Large scale renewable generation is increasingly installed into power grids all over the world in an effort to reduce CO2 from electricity sector. Yet, the inherent intermittent nature of renewable generations, such as wind and solar, introduces high uncertainty into system operation and may compromise the grid stability. As such, stability assessment of power grid with high penetration of renewables is an important issue. Due to the renewable generations uncertainty, the transient stability of renewable power grid can be assessed by simulating power systems dynamics with different level of renewable generations, which leads to highly computational cost. In this paper, we present a robust stability certificate that can rigorously guarantee the grids stability with respect to the variation in power injections. Interestingly, quadratic Lyapunov function approach is presented to transient stability assessment, offering real-time construction of stability certificates. The effectiveness of the proposed techniques is numerically illustrated on a number of IEEE test cases.
{"title":"Robust transient stability assessment of renewable power grids","authors":"T. Vu, K. Turitsyn","doi":"10.1109/ICSET.2016.7811748","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811748","url":null,"abstract":"Large scale renewable generation is increasingly installed into power grids all over the world in an effort to reduce CO2 from electricity sector. Yet, the inherent intermittent nature of renewable generations, such as wind and solar, introduces high uncertainty into system operation and may compromise the grid stability. As such, stability assessment of power grid with high penetration of renewables is an important issue. Due to the renewable generations uncertainty, the transient stability of renewable power grid can be assessed by simulating power systems dynamics with different level of renewable generations, which leads to highly computational cost. In this paper, we present a robust stability certificate that can rigorously guarantee the grids stability with respect to the variation in power injections. Interestingly, quadratic Lyapunov function approach is presented to transient stability assessment, offering real-time construction of stability certificates. The effectiveness of the proposed techniques is numerically illustrated on a number of IEEE test cases.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132896327","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}
Pub Date : 2016-11-01DOI: 10.1109/ICSET.2016.7811790
H. Dang, B. Delinchant, F. Wurtz
The most energy in buildings is used for space cooling and heating. Thus, the thermal analysis is necessary to reach thermal comfort and energy efficiency in buildings. In this paper, we present a thermal envelope modeling based on thermal-electrical analogy for thermal behavior simulation. The research object is a real platform inside our laboratory building in France. To illustrate this study, two thermal zone model represent two room of this platform, and they are surrounded by another thermal zones of laboratory building. Their parameters have been identified from envelope properties. Then, these models are implemented in a simple equivalent electric circuit, simulated and validated with measurement data.
{"title":"Toward building energy management: Electric analog modeling for thermal behavior simulation","authors":"H. Dang, B. Delinchant, F. Wurtz","doi":"10.1109/ICSET.2016.7811790","DOIUrl":"https://doi.org/10.1109/ICSET.2016.7811790","url":null,"abstract":"The most energy in buildings is used for space cooling and heating. Thus, the thermal analysis is necessary to reach thermal comfort and energy efficiency in buildings. In this paper, we present a thermal envelope modeling based on thermal-electrical analogy for thermal behavior simulation. The research object is a real platform inside our laboratory building in France. To illustrate this study, two thermal zone model represent two room of this platform, and they are surrounded by another thermal zones of laboratory building. Their parameters have been identified from envelope properties. Then, these models are implemented in a simple equivalent electric circuit, simulated and validated with measurement data.","PeriodicalId":164446,"journal":{"name":"2016 IEEE International Conference on Sustainable Energy Technologies (ICSET)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114120978","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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