IEEE Canadian Journal of Electrical and Computer Engineering最新文献

{"title":"Design and Real-Time Validation of Higher Order Sliding Mode Observer-Based Integral Sliding Mode MPPT Control for a DC Microgrid","authors":"Vijaya Kumar Dunna;Kumar Pakki Bharani Chandra;Pravat Kumar Rout;Binod Kumar Sahu","doi":"10.1109/ICJECE.2022.3211470","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3211470","url":null,"abstract":"In a photovoltaic (PV) system-based microgrid, maximum power point tracking (MPPT) control plays a crucial role to improve the efficiency and stability. Since the past few years, one of the key control schemes to enhance the effectiveness of the microgrid is the observer-based MPPT control. This article proposes a higher order sliding mode observer (HOSMO)-based integral sliding mode control (ISMC) for MPPT control to ensure an efficient operation of a closed-loop dc microgrid. The proposed MPPT control is mainly focused on obtaining a chatter-free output voltage and stabilized output power from the PV-system-based microgrid and further ensure insensitivity to uncertainties and reduction in steady-state error. ISMC is applied to carry out finite-time stabilization throughout the entire response of the system. To justify the efficacy of the proposed approach, various test scenarios are simulated in real-time, and the performance is investigated through extensive comparative results. The MATLAB simulations and real-time simulation results achieved with OPAL-RT are compared. The superior performance of the proposed approach is observed in terms of high efficiency, good accuracy, and robust performance under varying meteorological conditions.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 4","pages":"418-425"},"PeriodicalIF":0.0,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68030084","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":"Multipath Canceled RF Fingerprinting for Wireless OFDM Devices Based on Hammerstein System Parameter Separation","authors":"Honglin Yuan;Yan Yan;Zhihua Bao;Chen Xu;Juping Gu;Jiangzhou Wang","doi":"10.1109/ICJECE.2022.3217328","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3217328","url":null,"abstract":"Radio frequency fingerprint (RFF) based authentication of wireless devices can be used in the fields of the access security at the physical-layer of wireless networks and radio spectrum management. However, the stability of RFF is easily damaged by the wireless multipath fading channel in mobile communications. An RFF fingerprinting method with the nonlinearity and in-phase and quadrature (IQ) imbalance of the transmitter is proposed for chunk-based wireless orthogonal frequency division multiplexing (OFDM) devices based on a Hammerstein system parameter separation technique, which cancels the adverse influence of the time-varying multipath channel. First, the parameters of the nonlinear model of the transmitter and finite impulse response (FIR) of the wireless multipath channel are estimated with the Hammerstein system parameter separation technique. Second, the best IQ imbalance parameter combination is obtained with the FIR estimation of the channel. Finally, the estimated parameters of the nonlinear model and IQ imbalance are used as RFFs to classify the transmitters. Theoretical analyses and numerical experiments demonstrate that the obtained RFFs are stable and the fusion authentication of transmitters with subtle differences from the same model and same series is feasible using the novel method.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 4","pages":"401-408"},"PeriodicalIF":0.0,"publicationDate":"2022-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68030086","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 Fast and Accurate Fault Location Technique for High Voltage Direct Current (HVDC) Systems Une technique rapide et précise de localisation des défauts pour les systèmes de courant continu à haute tension (CCHT)","authors":"Jude Inwumoh;Craig A. Baguley;Kosala Gunawardane","doi":"10.1109/ICJECE.2022.3217262","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3217262","url":null,"abstract":"To minimize the outage time and costs associated with faults on high voltage direct current (HVdc) transmission lines it is critical to locate faults in an accurate and sufficiently fast manner. Current fault location techniques based on artificial intelligence (AI) are accurate but require fault data from rectifying and inverting ends. This necessitates a communications system and incurs high computational burdens. Therefore, a novel fault location technique is proposed that requires fault data only from one end, eliminating the need for a communication system. It employs support vector machine (SVM) algorithms to reduce the time needed to locate faults through fault classification. After classification, Gaussian process regression (GPR) is used for location identification. The proposed technique is tested under real time simulation conditions. The test results show the SVM can classify different fault types with an accuracy of 99.7%, while the GPR is able to locate faults within 0.5197 s with a root mean square error (RMSE) value of 6.52e−5%. The performance of the technique is further investigated under varying fault impedance levels. The results show the proposed technique is robust, even under high impedance fault conditions.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 4","pages":"383-393"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68030719","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":"IPWM Based IBMSC DC-AC Converter Using Solar Power for Wide Voltage Conversion System Convertisseur DC-AC IBMSC basé sur l’IPWM et utilisant l’énergie solaire pour un système de conversion à large tension","authors":"K. Suresh;E. Parimalasundar","doi":"10.1109/ICJECE.2022.3207873","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3207873","url":null,"abstract":"This article proposes isolated bidirectional micro dc-ac single phase controlled (IBMSC) converter based on in-phase–voltage pulsewidth modulation (IPWM). This resonant IPWM converter, ratio of voltage conversion can be controlled from 0 to \u0000<inline-formula> <tex-math>$infty $ </tex-math></inline-formula>\u0000. So, this converter is highly referred for huge range voltage conversion. However, voltage conversion ratio determines power transfer direction and duty ratio. Power flow direction and duty cycle value can be varying smoothly, so it is suitable for dc-ac bidirectional power conversion application. Inverter mode and also rectifier mode are possible from bidirectional operation, which is controlled by a unified current controller. The proposed solution can achieve smooth switching grid operation with high efficiency. Working principle, design procedure, control strategy, and characteristics of the proposed converter are implemented with a prototype model of power rating 500 W with a voltage range of 20–50 V to test the ability of withstanding. Performance, feasibility, and effectiveness of the proposed converter are tested with this hardware test-bench model.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 4","pages":"394-400"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68030720","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":"IEEE Canadian Journal of Electrical and Computer Engineering Publication Information","authors":"","doi":"10.1109/ICJECE.2022.3217704","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3217704","url":null,"abstract":"Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 3","pages":"C2-C2"},"PeriodicalIF":0.0,"publicationDate":"2022-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9349829/9944186/09956002.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68033756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Guest Editorial Special Edition of the IEEE-CJECE","authors":"Hossam Hassanein;Shahrokh Valaee","doi":"10.1109/ICJECE.2022.3211760","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3211760","url":null,"abstract":"Welcome to a Special Issue of the IEEE Canadian Journal of Electrical and Computer Engineering (IEEE-CJECE), which presents articles in the research areas of the Journal’s Former Area Editor, Dr. Sameh Sourour, in his memorial. Sameh Sorour was with the School of Computing at Queen’s University, Kingston, ON, Canada, where he was leading research in mobile edge computing, edge learning and autonomous vehicles with funding from federal, provincial and industry sources. He received his B.Sc. and M.Sc. degrees from Alexandria University, Alexandria, Egypt, in 2002 and 2006, respectively, and the Ph.D. from the University of Toronto, Toronto, ON, Canada, in 2011. His Ph.D. thesis was nominated for the Governor General’s Gold Medal Award. After his graduation, he held a MITACS industrial postdoctoral fellowship with Siradel Canada and the University of Toronto. Prior to moving to Queen’s University in 2019, he held another postdoctoral fellowship at the King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia, a Lecturer position at the King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia, and an Assistant Professor position at the University of Idaho, Moscow, ID, USA. During his Ph.D. degree and postdoctoral fellowships, he led several research projects with industrial partners and government agencies, such as LG Korea, the European Space Agency, the Canadian National Institute for the Blind (CNIB), and Siradel France. Dr. Sorour was a Senior Member of the IEEE and an Editor for IEEE Communications Letters. Also, he was an Area Editor in the IEEE-CJECE. His research and educational interests lied in the broad areas of advanced computing, learning, and networking technologies for cyber-physical and autonomous systems. The Guest Editors of this issue are 1) Prof. Hossam Hassanein, Director of School of Computing, Queen’s University, where Dr. Sorour held his last academic title; 2) Prof. Shahrokh Valaee, the Ph.D. advisor of Dr. Sourour at the University of Toronto.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 3","pages":"191-191"},"PeriodicalIF":0.0,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9349829/9944186/09944387.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68033758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the DoF of X-Networks With Synergistic Alternating CSIT: A Step Towards Integrated Communication and Sensing","authors":"Ahmed Wagdy Shaban;Mohamed Seif;Tamer Khattab;Amr El-Keyi;Mohammed Nafie;Nizar Zorba","doi":"10.1109/ICJECE.2022.3195957","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3195957","url":null,"abstract":"The coexistence of communication and sensing services in the next wireless communication systems, i.e., beyond 5G and 6G systems, revive the central role of interference management techniques such as interference alignment, coordinated multipoint transmission, and cell-free massive multiple-input–multiple-output (MIMO), in defeating interference and achieving the network capacity. In this article, we consider the \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$K$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000-user single-input–single-output (SISO) X-channel and its variants (\u0000&lt;inline-formula&gt; &lt;tex-math&gt;$2 times K$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000 and \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$K times 2$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000) in fast-fading environments. This can theoretically model many practical use cases for beyond 5G and 6G networks. For instance, it can model the case of having \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$K$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000 cars communicating with another \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$K$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000 cars, while former cars are sensing environment using the latter ones (in a cooperative, bistatic, and active approach) over the same time and frequency resources. We assume that the transmitters have access to synergistic alternating channel state information at the transmitter (CSIT) where it alternates between three states: perfect (P), delayed (D), and no-CSIT (N), and these states are associated with fractions of time denoted by \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$lambda _{P}$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000, \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$lambda _{D}$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000, and \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$lambda _{N}$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000, respectively. We develop novel degree-of-freedom (DoF) achievability schemes that exploit the synergy of the instantaneous CSIT and the delayed CSIT to retrospectively align interference in the subsequent channel uses. In particular, we show that the sum DoF of the \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$K$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000-user SISO X-channel is at least \u0000&lt;inline-formula&gt; &lt;tex-math&gt;${2K}/{K + 1}$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000, using a two-phase transmission scheme over finite symbols channel extension and under a certain distribution of the CSIT availability of \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$Lambda (lambda _{P}=({1}/{3}), lambda _{D}= ({1}/{3}), lambda _{N}=({1}/{3}))$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000. This achievability result can be considered as a tight lower bound where it coincides with the best lower bound known for the same network but with partial output feedback instead of alternating CSIT. In addition, it shows that the role of synergistically alternating CSIT with distribution \u0000&lt;inline-formula&gt; &lt;tex-math&gt;$Lambda ({1}/{3},{1}/{3},{1}/{3})$ &lt;/tex-math&gt;&lt;/inline-formula&gt;\u0000 is equivalent to the one of the partial output feedback. Moreover, we show the optimality of the proposed two-phase-based scheme using a simple combinatorial proof. This establishes a DoF lower bound, which is strictly better than the bes","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 3","pages":"199-214"},"PeriodicalIF":0.0,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9349829/9944186/09940485.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68033761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel Sub-Harmonic-Based Self-Excited Brushless Wound Rotor Synchronous Machine","authors":"Syed Sabir Hussain Bukhari;Madad Ali Shah;Jorge Rodas;Mohit Bajaj;Jong-Suk Ro","doi":"10.1109/ICJECE.2022.3200146","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3200146","url":null,"abstract":"This article aims to realize a self-excited wound rotor synchronous machine (WRSM) topology established while considering the subharmonic field excitation scheme. Unlike the conventional subharmonic-based brushless WRSMs that require a dual-inverter configuration, the proposed topology uses a single inverter and a dual-armature winding pattern. The employed dual-armature winding configuration involves a four-pole main armature winding (ABC) and a two-pole open winding (X). The ABC winding is supplied with a three-phase current from a single customary current source inverter (CSI), whereas the X winding carries no current due to its open winding pattern and is responsible for generating subharmonic magnetomotive force (MMF) in the air gap along with the fundamental-harmonic MMF. The fundamental-harmonic MMF is utilized to create a four-pole stator field, while the subharmonic MMF is used to induce the harmonic current in the two-pole harmonic winding of the rotor. The generated harmonic current is rectified to energize the rotor field winding and develop a four-pole rotor field. The electromagnetic interaction of the four-pole stator and rotor fields generates torque. As the proposed subharmonic-based self-excited brushless WRSM employs a single inverter for its brushless operation, this makes it cost-effective compared to the conventional dual-inverter subharmonic-based brushless WRSM topologies. The proposed self-excited brushless WRSM topology is validated through the finite-element analysis (FEA). JMAG-Designer tool is employed to carry out FEA for a four-pole, 24-slot (4p24s) machine. The quantitative relative performance evaluation of the proposed self-excited WRSM topology with the recently developed dual-inverter-controlled subharmonic-based brushless WRSM topology is presented to show its better performance in terms of average, maximum, and minimum torques and torque ripple.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 4","pages":"365-374"},"PeriodicalIF":0.0,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68030717","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":"Deep Incremental Learning for Personalized Human Activity Recognition on Edge Devices","authors":"Shady Younan;Mervat Abu-Elkheir","doi":"10.1109/ICJECE.2022.3199227","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3199227","url":null,"abstract":"Tracking human daily activities is a useful functionality supported in many applications, especially with the pervasive use of wearable devices. State-of-the-art human activity recognition (HAR) uses machine or deep learning techniques to identify activities based on sensor readings. However, these models represent patterns from standardized experiment setups, with limited diversity when it comes to the individuals involved in data collection. This leads to limited success of HAR in real deployment scenarios, where individuals perform the same activity in different ways. Training models from scratch on real-time data streams is challenging due to the computational complexity of machine and deep learning architectures. In this article, we propose an incremental learning model for HAR that tweaks a deep learning model pretrained on a standardized HAR dataset and incrementally trains on newly generated individuals personalized data on their personal devices. The proposed solution promotes the preservation of data privacy, improves the model performance in terms of accuracy and efficiency without having to retrain from scratch, and tweaks the model according to personalized activity patterns. Extensive experiments show improvement of the base model’s accuracy up to 19% after incrementally training the model on filtered users’ datasets for the standing, walking, and running activities.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 3","pages":"215-221"},"PeriodicalIF":0.0,"publicationDate":"2022-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68033760","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":"MIMO Antenna Mutual Coupling Reduction Using Modified Inverted-Fork Shaped Structure","authors":"Jogesh Chandra Dash;Shilpa Kharche;G. Shrikanth Reddy","doi":"10.1109/ICJECE.2022.3201054","DOIUrl":"https://doi.org/10.1109/ICJECE.2022.3201054","url":null,"abstract":"This article presents, a mutual coupling reduction technique between a very closely spaced (1.8 mm) two-element microstrip-based multiple-input multiple-output (MIMO) antennas using a modified inverted-fork-shaped decoupling (m-IFSD) structure. The m-IFSD structure consists of an inverted fork and a cross-shaped structure with a shorted via. The combined effect of inverted-fork and shorted cross-shaped structure results in mutual coupling reduction below −35 dB between adjacent antenna elements. The decoupling technique is analyzed using an approximate transmission-line model and field distribution. Furthermore, the two-element MIMO antenna design is extended to an eight-element MIMO configuration to improve the MIMO diversity. To verify the proposed isolation technique a two-element MIMO antenna prototype is fabricated and measured. The proposed MIMO antenna exhibits a low mutual coupling (<−35 dB) with good impedance matching (<−10 dB) at 5.45 GHz. The MIMO antenna provided a total active reflection coefficient (TARC) less than −10 dB and envelop correlation coefficient (ECC) (for isotropic propagation scenario) less than 0.5. Finally, the ECC of the proposed MIMO antenna system is analyzed for a realistic Gaussian/uniform propagation scenario for various incidence angles and angular spreads to better understand the effect of the mutual coupling reduction technique.","PeriodicalId":100619,"journal":{"name":"IEEE Canadian Journal of Electrical and Computer Engineering","volume":"45 4","pages":"375-382"},"PeriodicalIF":0.0,"publicationDate":"2022-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68030718","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}