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14 pages, 4087 KiB

Open AccessArticle

Design and Characteristics of Underwater Stacked Capacitive Power Transfer Coupler and Analysis of Propagation in Water Medium

by Kyeungwon Bang and Sangwook Park

Appl. Sci. 2025, 15(4), 1901; https://doi.org/10.3390/app15041901 - 12 Feb 2025

Viewed by 717

Abstract

This study provides a theoretical analysis of how the electrical characteristics of the medium affect the propagation of electric fields. Every medium has specific electrical conductivity and permittivity values and can be evaluated as a good conductor or a good dielectric depending on [...] Read more.

This study provides a theoretical analysis of how the electrical characteristics of the medium affect the propagation of electric fields. Every medium has specific electrical conductivity and permittivity values and can be evaluated as a good conductor or a good dielectric depending on the ratio of conduction current to displacement current. The strength of the electric field decreases significantly with the propagation distance due to the influence of high conductivity. In conclusion, even media with a high permittivity may be unsuitable for improving the performance of the capacitive power transfer (CPT) system depending on its conductivity. The analysis was verified for four types of water with different conductivities. In addition, we designed a stacked CPT coupler structure and analyzed its underwater transfer characteristics. In conclusion, unlike the parallel CPT coupler, the stacked CPT coupler is relatively disadvantageous for underwater use. Full article

(This article belongs to the Special Issue Electric Power Applications II)

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13 pages, 3524 KiB

Open AccessCommunication

Design of Four-Plate Parallel Dynamic Capacitive Wireless Power Transfer Coupler for Mobile Robot Wireless-Charging Applications

by Hongguk Bae and Sangwook Park

Appl. Sci. 2025, 15(2), 823; https://doi.org/10.3390/app15020823 - 15 Jan 2025

Cited by 1 | Viewed by 1499

Abstract

A detailed theoretical design of an electric resonance-based coupler for dynamic wireless power transfer (DWPT) at the mobile robot level is presented. The scattering matrix of the coupler was derived by transforming and multiplying transmission matrices for each circuit network in a practical [...] Read more.

A detailed theoretical design of an electric resonance-based coupler for dynamic wireless power transfer (DWPT) at the mobile robot level is presented. The scattering matrix of the coupler was derived by transforming and multiplying transmission matrices for each circuit network in a practical equivalent circuit that accounted for loss resistance. This theoretical approach was validated through equivalent circuit models, yielding results consistent with 3D full-wave simulations and showing an error rate of less than 1%. Additionally, a null-power point characteristic, where efficiency sharply decreases when the receiver moves outside the transmitter’s range, was observed. The detailed theoretical design of the practical equivalent circuit for electric resonance-based dynamic WPT couplers is expected to contribute to the design of couplers for various specifications in future applications. Full article

(This article belongs to the Special Issue State-of-the-Art of Power Systems)

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14 pages, 5948 KiB

Open AccessArticle

Extended-Distance Capacitive Wireless Power Transfer System Based on Generalized Parity–Time Symmetry

by Xujian Shu, Riming Ou, Guoxin Wu, Jingjing Yang and Yanwei Jiang

Electronics 2024, 13(23), 4731; https://doi.org/10.3390/electronics13234731 - 29 Nov 2024

Cited by 1 | Viewed by 912

Abstract

A capacitive wireless power transfer (CPT) system based on parity–time (PT) symmetry achieves constant output characteristics under distance variation without additionally increasing the system complexity of the control strategy, where the concept of PT symmetry is derived from quantum mechanics, and the systems [...] Read more.

A capacitive wireless power transfer (CPT) system based on parity–time (PT) symmetry achieves constant output characteristics under distance variation without additionally increasing the system complexity of the control strategy, where the concept of PT symmetry is derived from quantum mechanics, and the systems satisfying PT symmetry are invariant under space and time inversion. However, the exact PT-symmetric region (i.e., strong coupling region) of the general system is limited by the symmetry of the structure and parameters. To overcome this limitation, a novel generalized parity–time (GPT)-symmetric CPT system is proposed in this article. According to the equivalent circuit method, the circuit model of the proposed system is built, and the transfer characteristics are analyzed. Furthermore, a prototype is implemented to verify the feasibility of the proposed CPT system. The results show that the PT-symmetric region is extended by 169.23% compared with the traditional PT-based CPT system, and a constant output power of 21.5 W is transferred with a constant transfer efficiency of 90%. Full article

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23 pages, 20891 KiB

Open AccessArticle

Design of Stabilizing Network for Capacitive Power Transfer Transmitter Operating at Maximum Power Transfer Limiting the Voltage Gain in Resonant Capacitors

by Eduardo Salvador Estevez-Encarnacion, Leobardo Hernandez-Gonzalez, Jazmin Ramirez-Hernandez, Oswaldo Ulises Juarez-Sandoval, Pedro Guevara-Lopez and Guillermo Avalos Arzate

Electronics 2024, 13(19), 3859; https://doi.org/10.3390/electronics13193859 - 29 Sep 2024

Viewed by 1189

Abstract

Capacitive power transfer (CPT) is a technology that is emerging as an alternative to inductive power transfer (IPT) in applications requiring low to medium power. A great interest has been developed in the implementation of CPT systems in battery charging systems, where a [...] Read more.

Capacitive power transfer (CPT) is a technology that is emerging as an alternative to inductive power transfer (IPT) in applications requiring low to medium power. A great interest has been developed in the implementation of CPT systems in battery charging systems, where a condition to compete with IPT systems is the need to increase the power transfer in the CPT systems without significant losses. This paper puts forth a design methodology for a stabilizing network, which has been applied to a CPT system. This methodology has been developed through impedance analysis of the circuit, in order to achieve maximum power transfer, with total gains of voltage and current reaching a value close to unity. The methodology allows for the calculation of the value of the components of the stabilizing network, which has been designed with the objective of stabilizing the resonant frequency against changes in the capacitance of the transmission plates. To validate the design procedure, an experimental prototype was developed at 25 W and an operational frequency of 1.55 MHz. The results obtained validate the design methodology. Full article

(This article belongs to the Section Power Electronics)

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16 pages, 4126 KiB

Open AccessArticle

A Novel Coupler of Capacitive Power Transfer for Enhancing Underwater Power Transfer Characteristics

by Xueqiang Zhang and Jing Lian

Electronics 2024, 13(1), 74; https://doi.org/10.3390/electronics13010074 - 22 Dec 2023

Cited by 2 | Viewed by 1637

Abstract

Compared to inductive power transfer (IPT) technology, capacitive power transfer (CPT) technology offers unique advantages such as being cost-effective, lightweight, and free from eddy-current losses, making it more suitable for underwater power transfer. Unlike air, water can conduct electricity and the electric conductivity [...] Read more.

Compared to inductive power transfer (IPT) technology, capacitive power transfer (CPT) technology offers unique advantages such as being cost-effective, lightweight, and free from eddy-current losses, making it more suitable for underwater power transfer. Unlike air, water can conduct electricity and the electric conductivity of different kinds of waters varies with different ion concentrations, which would greatly affect the equivalent model of the underwater couplers. To address this issue, multiple types of underwater coupler working in different kinds of water are compared and analyzed. The influence of the electrical conductivity of water on the capacitive coupler is comprehensively analyzed, and the novel capacitive coupler and its equivalent model are proposed to improve power transfer efficiency. To verify the theoretical analysis, the double-sided LC-compensated CPT circuit is built and tap water is used in the experiment. The experimental results are consistent with the theoretical analysis. In addition, the experimental results also validate the superiority of the proposed capacitive coupler compared to existing research. Full article

(This article belongs to the Special Issue Wireless Power Transfer Technology and Its Applications)

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Graphical abstract

43 pages, 6315 KiB

Open AccessReview

A Review of Capacitive Power Transfer Technology for Electric Vehicle Applications

by Jiantao Zhang, Shunyu Yao, Liangyi Pan, Ying Liu and Chunbo Zhu

Electronics 2023, 12(16), 3534; https://doi.org/10.3390/electronics12163534 - 21 Aug 2023

Cited by 9 | Viewed by 3352

Abstract

Electric Vehicle (EV) wireless power transfer technology is an excellent solution to propel EVs forward. The existing wireless power transfer technology for EVs based on Inductive Power Transfer (IPT) technology has the drawbacks of large size, high weight, and high eddy current loss, [...] Read more.

Electric Vehicle (EV) wireless power transfer technology is an excellent solution to propel EVs forward. The existing wireless power transfer technology for EVs based on Inductive Power Transfer (IPT) technology has the drawbacks of large size, high weight, and high eddy current loss, limiting the further application of this technology. Capacitive Power Transfer (CPT) technology, with its advantages of low cost and light weight, has attracted widespread focus in recent years and has great potential in the field of EV wireless power transfer. This paper begins with the principle of CPT, introduces the potential and development history of CPT technology in the field of EV wireless power transfer, and then reviews the coupling mechanism and resonance compensation network of the CPT system to satisfy the requirements of EV wireless power transfer, including the coupling mechanism of EV static power transfer and dynamic power transfer, and the high-performance resonance compensation network to the requirements of EV wireless power transfer. Finally, this paper reviews the existing problems of CPT technology in the field of EV wireless power transfer and summarizes its future development directions. Full article

(This article belongs to the Topic Advanced Wireless Charging Technology)

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26 pages, 5923 KiB

Open AccessFeature PaperReview

A Review of Power Transfer Systems for Light Rail Vehicles: The Case for Capacitive Wireless Power Transfer

by Kyle John Williams, Kade Wiseman, Sara Deilami, Graham Town and Foad Taghizadeh

Energies 2023, 16(15), 5750; https://doi.org/10.3390/en16155750 - 1 Aug 2023

Cited by 7 | Viewed by 2729

Abstract

Light rail vehicles (LRVs) are increasingly in demand to sustainably meet the transport needs of growing populations in urban centres. LRVs have commonly been powered from the grid by direct-contact overhead catenary systems (OCS); however, catenary-free direct-contact systems, such as via a “hidden [...] Read more.

Light rail vehicles (LRVs) are increasingly in demand to sustainably meet the transport needs of growing populations in urban centres. LRVs have commonly been powered from the grid by direct-contact overhead catenary systems (OCS); however, catenary-free direct-contact systems, such as via a “hidden rail”, are popular for new installations. Wireless power transfer (WPT) is an emerging power transfer (PT) technology for e-transport with several advantages over direct contact systems, including improved aesthetics and reduced maintenance requirements; however, they are yet to be utilised in LRV systems. This paper provides a review of existing direct-contact and wireless PT technologies for LRVs, followed by an in-depth critical assessment of inductive power transfer (IPT) and capacitive power transfer (CPT) technologies for LRVs. In particular, the feasibility and advantages of CPT for powering LRVs are presented, highlighting the efficacy of CPT with respect to power transfer capability, safety, and other factors. Finally, limitations and recommendations for future works are identified. Full article

(This article belongs to the Special Issue High-Power and Efficient Wireless Charging for Electrified Transportation)

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14 pages, 4364 KiB

Open AccessArticle

Analysis and Design of a Dual-Frequency Capacitive Power Transfer System to Reduce Coupler Voltage Stress

by Sen Yang, Yao Zhang, Yiming Zhang, Yongchao Wang, Zhulin Wang, Bo Luo and Ruikun Mai

Electronics 2023, 12(6), 1274; https://doi.org/10.3390/electronics12061274 - 7 Mar 2023

Cited by 3 | Viewed by 2002

Abstract

In a capacitive power transfer (CPT) system, the coupling capacitance formed between the coupling plates is very small only in the pF or nF range, which leads to high voltage stress among the coupling plates during energy transmission, which increases the risk of [...] Read more.

In a capacitive power transfer (CPT) system, the coupling capacitance formed between the coupling plates is very small only in the pF or nF range, which leads to high voltage stress among the coupling plates during energy transmission, which increases the risk of an electrical breakdown between the coupled plates. To solve this problem, a novel dual-frequency CPT system is proposed in this paper, which uses the “peak clipping” effect caused by the superposition of the fundamental wave and third harmonic wave to reduce the voltage stress of the coupled plates. Through the detailed analysis of the working principle of the CPT system, it is shown that the dual-frequency CPT system can indeed reduce the high voltage stress among the coupled plate to 84.3% of the equivalent single-frequency system and can also reduce the inverter conduction losses to 90%. A 200 W prototype is designed with the proposed scheme, and the experimental results confirm the correctness of the theoretical derivation. Full article

(This article belongs to the Collection Wireless Power Transfer: Material, Technologies, and Applications)

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18 pages, 8188 KiB

Open AccessArticle

Analysis of Series-Parallel (SP) Compensation Topologies for Constant Voltage/Constant Current Output in Capacitive Power Transfer System

by Shiqi Li, Chunlin Tang, Hao Cheng, Zhulin Wang, Bo Luo and Jing Jiang

Electronics 2023, 12(1), 245; https://doi.org/10.3390/electronics12010245 - 3 Jan 2023

Cited by 3 | Viewed by 2964

Abstract

This paper analyzed the four series-parallel (SP) compensation topologies to achieve constant current (CC) and voltage (CV) output characteristics and zero phase angle (ZPA) input conditions with fewer compensation components in the capacitive power transfer (CPT) system. There are three main contributions. Firstly, [...] Read more.

This paper analyzed the four series-parallel (SP) compensation topologies to achieve constant current (CC) and voltage (CV) output characteristics and zero phase angle (ZPA) input conditions with fewer compensation components in the capacitive power transfer (CPT) system. There are three main contributions. Firstly, the universal methodology of SP compensation topologies was constructed to achieve CC, CV output, and ZPA conditions. Secondly, four specific SP compensation topologies were investigated and summarized, including double-sided LC, double-sided CL, CL−LC, and LC−CL topologies. Their input–output characteristics are provided, and system efficiency is analyzed. Thirdly, the CL−LC and LC−CL topologies were proposed to realize ZPA conditions under CC and CV output without any external regulating circuit. A CV output LC−CL experiment prototype was implemented to validate the theoretical analysis. Full article

(This article belongs to the Special Issue Wireless Power Transfer and Wireless Energy Harvest)

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23 pages, 10522 KiB

Open AccessReview

Research and Application of Capacitive Power Transfer System: A Review

by Zhulin Wang, Yiming Zhang, Xinghong He, Bo Luo and Ruikun Mai

Electronics 2022, 11(7), 1158; https://doi.org/10.3390/electronics11071158 - 6 Apr 2022

Cited by 35 | Viewed by 13009

Abstract

Capacitive power transfer (CPT) uses an electric field as the transfer medium to achieve wireless power transfer (WPT). Benefitting from the low eddy current loss, simple system structure and strong plasticity of the coupling coupler, the CPT system has recently gained much attention. [...] Read more.

Capacitive power transfer (CPT) uses an electric field as the transfer medium to achieve wireless power transfer (WPT). Benefitting from the low eddy current loss, simple system structure and strong plasticity of the coupling coupler, the CPT system has recently gained much attention. The CPT system has significantly improved transfer power, system efficiency, and transfer distance due to continuous research and discussion worldwide. This review briefly presents the basic working principle of the CPT system and summarizes the theoretical research in four aspects, including coupling coupler and high-frequency power converter. Following this, the review focuses on research in six key directions, including system modelling and efficiency optimization. The application of CPT technology in five fields, including medical devices and transportation, is also discussed. This review introduces the progress of CPT research in recent years, hoping to serve as a reference for researchers, to promote the further research and application of the CPT system. Full article

(This article belongs to the Collection Wireless Power Transfer: Material, Technologies, and Applications)

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25 pages, 7603 KiB

Open AccessArticle

A General Parameter Optimization Method for a Capacitive Power Transfer System with an Asymmetrical Structure

by Jinglin Xia, Xinmei Yuan, Sizhao Lu, Weiju Dai, Tong Li, Jun Li and Siqi Li

Electronics 2022, 11(6), 922; https://doi.org/10.3390/electronics11060922 - 16 Mar 2022

Cited by 6 | Viewed by 2494

Abstract

Capacitive power transfer (CPT) is an attractive wireless power transfer (WPT) technology and it has been widely studied in many applications. Symmetrical structures and high-order compensation networks are always produced as optimization results and common configurations for high-efficiency CPT systems. However, in space-limited [...] Read more.

Capacitive power transfer (CPT) is an attractive wireless power transfer (WPT) technology and it has been widely studied in many applications. Symmetrical structures and high-order compensation networks are always produced as optimization results and common configurations for high-efficiency CPT systems. However, in space-limited scenarios, an asymmetric structure tends to be a better choice. The related large number of high-order asymmetric system parameters is a key problem in parameter design. In this study, a general parameter design method that is based on reactive power optimization is proposed for an electric field resonance-based CPT system with an asymmetric six-plate coupler. The reactive power in the compensation network was analyzed and optimized under the constraint of transferred power. With equal reactive power, the optimization complexity was significantly reduced and the optimized system parameters were provided. To validate the effectiveness of the proposed method, a 1 MHz, 3.2 kW asymmetric CPT protype with 100 mm gap distance was implemented. The results indicate that, with the optimized parameters, high system efficiency can be achieved when the system’s volume is reduced. At the rated power, about 95% DC–DC overall efficiency was achieved through a 6-pF coupling capacitor. Full article

(This article belongs to the Collection Wireless Power Transfer: Material, Technologies, and Applications)

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18 pages, 7547 KiB

Open AccessArticle

A Novel Compensation Circuit for Capacitive Power Transfer System to Realize Desired Constant Current and Constant Voltage Output

by Bo Dong, Yang Chen, Jing Lian and Xiaohui Qu

Energies 2022, 15(4), 1523; https://doi.org/10.3390/en15041523 - 18 Feb 2022

Cited by 1 | Viewed by 2282

Abstract

Capacitive power transfer (CPT) technique possesses the advantages of safety, isolation, low cost, and insensitivity to conductive barriers. To charge lithium-ion batteries, CPT should possess the output profile consisting of first constant current (CC) output and later constant voltage (CV) output. To fulfill [...] Read more.

Capacitive power transfer (CPT) technique possesses the advantages of safety, isolation, low cost, and insensitivity to conductive barriers. To charge lithium-ion batteries, CPT should possess the output profile consisting of first constant current (CC) output and later constant voltage (CV) output. To fulfill the output profile, many power switches or compensation components are added in the CPT circuit, which is not expected due to the bulky size and additional losses. To reduce the redundancy of the CPT system, an L_x-PS CPT circuit with only five compensation components is proposed in this paper. After a systematic analysis and a parameter design procedure, the proposed CPT circuit can realize input ZPA at both CC and CV modes. In addition, the output current at CC mode and the output voltage at CV mode are all adjustable based on the charging demands of different loads. Finally, simulations are done to prove the analysis in this paper. Compared to previous research, the CPT circuit proposed in this paper can not only achieve the charging demands of lithium-ion batteries, but also reduce the redundancy of the whole system. Full article

(This article belongs to the Special Issue Current Research and Future Development on Wireless Power Transfer Technology)

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12 pages, 2891 KiB

Open AccessArticle

8-Plate Multi-Resonant Coupling Using a Class-E² Power Converter for Misalignments in Capacitive Wireless Power Transfer

by Yashwanth Bezawada and Shirshak K. Dhali

Electronics 2022, 11(4), 635; https://doi.org/10.3390/electronics11040635 - 18 Feb 2022

Cited by 2 | Viewed by 2023

Abstract

Misalignment is a common issue in wireless power transfer systems. It shifts the resonant frequency away from the operating frequency that affects the power flow and efficiency from the charging station to the load. This work proposes a novel capacitive wireless power transfer [...] Read more.

Misalignment is a common issue in wireless power transfer systems. It shifts the resonant frequency away from the operating frequency that affects the power flow and efficiency from the charging station to the load. This work proposes a novel capacitive wireless power transfer (CPT) using an 8-plate multi-resonant capacitive coupling to minimize the effect of misalignments. A single-active switch class-E² power converter is utilized to achieve multi-resonance through the selection of different resonant inductors. Simulations show a widening of the resonant frequency band which offers better performance than a regular 4-plate capacitive coupling for misalignments. The hardware results of the 8-plate multi-resonant coupling show an efficiency of 88.5% for the 20.8 W test, which is 18.3% higher than that of the regular 4-plate coupling. Because of the wider resonant frequency band {455–485 kHz}, compared with the regular 4-plate coupling, the proposed design minimized the output voltage drop by 15% for a 10% misalignment. Even for large misalignments, the 8-plate performance improved by 40% compared with the 4-plate coupling. Full article

(This article belongs to the Section Power Electronics)

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14 pages, 2615 KiB

Open AccessArticle

Optimal Solutions for Underwater Capacitive Power Transfer

by Hussein Mahdi, Bjarte Hoff and Trond Østrem

Sensors 2021, 21(24), 8233; https://doi.org/10.3390/s21248233 - 9 Dec 2021

Cited by 14 | Viewed by 3222

Abstract

Capacitive power transfer (CPT) has attracted attention for on-road electric vehicles, autonomous underwater vehicles, and electric ships charging applications. High power transfer capability and high efficiency are the main requirements of a CPT system. This paper proposes three possible solutions to achieve maximum [...] Read more.

Capacitive power transfer (CPT) has attracted attention for on-road electric vehicles, autonomous underwater vehicles, and electric ships charging applications. High power transfer capability and high efficiency are the main requirements of a CPT system. This paper proposes three possible solutions to achieve maximum efficiency, maximum power, or conjugate-matching. Each solution expresses the available load power and the efficiency of the CPT system as functions of capacitive coupling parameters and derives the required admittance of the load and the source. The experimental results demonstrated that the available power and the efficiency decrease by the increasing of the frequency from 300 kHz to 1 MHz and the separation distance change from 100 to 300 mm. The maximum efficiency solution gives 83% at 300 kHz and a distance of 100 mm, while the maximum power solution gives the maximum normalized power of 0.994 at the same frequency and distance. The CPT system can provide a good solution to charge electric ships and underwater vehicles over a wide separation distance and low-frequency ranges. Full article

(This article belongs to the Special Issue Selected Papers from 2021 IEEE MTT-S Wireless Power Transfer Conference)

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14 pages, 3803 KiB

Open AccessArticle

Optimal Load Determination of Capacitor–Inductor Compensated Capacitive Power Transfer System with Curved-Edge Shielding Layer

by Kehan Zhang, He Du, Bo Luo, Ruikun Mai, Baowei Song and Aiguo Patrick Hu

Electronics 2021, 10(23), 2961; https://doi.org/10.3390/electronics10232961 - 28 Nov 2021

Cited by 2 | Viewed by 2093

Abstract

Due to the natural low permittivity in vacuum, the voltage stresses on compensation capacitors and inductances in the capacitive power transfer (CPT) system are very high, which brings challenges to the design of CPT systems in practical applications. This paper used a three-cell [...] Read more.

Due to the natural low permittivity in vacuum, the voltage stresses on compensation capacitors and inductances in the capacitive power transfer (CPT) system are very high, which brings challenges to the design of CPT systems in practical applications. This paper used a three-cell structure analysis method for the CPT system to determine the optimal load for achieving the maximum power transfer or maximum efficiency transfer, through considering the maximum withstand voltage of the capacitor or inductor. A shielding layer with edge bending is designed to reduce the range of dangerous areas markedly. The simulation and experimental results verified the above conclusion. The prototype of the CPT system with transfer 3.1 kW across a 13 cm air gap and DC-DC transfer efficiency of 91.4% is built. Full article

(This article belongs to the Section Power Electronics)

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