The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Seongjoon Park - One of the best experts on this subject based on the ideXlab platform.
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Corrections to “Configuring RTK-GPS Architecture for System Redundancy in Multi-Drone Operations”
IEEE Access, 2020Co-Authors: Inseop Um, Seongjoon ParkAbstract:In the inter-delay analysis of the single RTCM propagation System proposed in [1] , we have used a misleading figure that does not correctly present the lifetime of single RTCM.
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Configuring RTK-GPS Architecture for System Redundancy in Multi-Drone Operations
IEEE Access, 2020Co-Authors: Inseop Um, Seongjoon ParkAbstract:The researches on Real Time Kinematic GPS (RTK-GPS) have been actively conducted to accurately estimate the location of drones, and there were many use cases applied to drones. However, such Systems using RTK-GPS do not provide the protection against network instability, failure of the components that make up the RTK-GPS service. In other words, availability is not provided to ensure the stability of the RTK-GPS. In this paper, we propose an architecture enabling Redundancy to improve the availability of RTK-GPS System by switching or parallelizing the GPS correction data sources. We also introduce how to propagate the correction messages through the drone network. After evaluating the System on empirical testbed, we validated that the correction messages propagated without delay, the message source was switched or multiplexed among several message sources through the proposed System when the network was unstable, and the switching time was short enough not to affect our propagation System. Consequently, we have confirmed availability through the proposed architecture of RTK-GPS Redundancy.
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Corrections to “Configuring RTK-GPS Architecture for System Redundancy in Multi-Drone Operations”
IEEE Access, 2020Co-Authors: Inseop Um, Seongjoon ParkAbstract:In the inter-delay analysis of the single RTCM propagation System proposed in [1], we have used a misleading figure that does not correctly present the lifetime of single RTCM. Thus, in the right column of page 6, we replace the Fig. 3 with the following figure.
Inseop Um - One of the best experts on this subject based on the ideXlab platform.
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Corrections to “Configuring RTK-GPS Architecture for System Redundancy in Multi-Drone Operations”
IEEE Access, 2020Co-Authors: Inseop Um, Seongjoon ParkAbstract:In the inter-delay analysis of the single RTCM propagation System proposed in [1] , we have used a misleading figure that does not correctly present the lifetime of single RTCM.
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Configuring RTK-GPS Architecture for System Redundancy in Multi-Drone Operations
IEEE Access, 2020Co-Authors: Inseop Um, Seongjoon ParkAbstract:The researches on Real Time Kinematic GPS (RTK-GPS) have been actively conducted to accurately estimate the location of drones, and there were many use cases applied to drones. However, such Systems using RTK-GPS do not provide the protection against network instability, failure of the components that make up the RTK-GPS service. In other words, availability is not provided to ensure the stability of the RTK-GPS. In this paper, we propose an architecture enabling Redundancy to improve the availability of RTK-GPS System by switching or parallelizing the GPS correction data sources. We also introduce how to propagate the correction messages through the drone network. After evaluating the System on empirical testbed, we validated that the correction messages propagated without delay, the message source was switched or multiplexed among several message sources through the proposed System when the network was unstable, and the switching time was short enough not to affect our propagation System. Consequently, we have confirmed availability through the proposed architecture of RTK-GPS Redundancy.
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Corrections to “Configuring RTK-GPS Architecture for System Redundancy in Multi-Drone Operations”
IEEE Access, 2020Co-Authors: Inseop Um, Seongjoon ParkAbstract:In the inter-delay analysis of the single RTCM propagation System proposed in [1], we have used a misleading figure that does not correctly present the lifetime of single RTCM. Thus, in the right column of page 6, we replace the Fig. 3 with the following figure.
George Varghese - One of the best experts on this subject based on the ideXlab platform.
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endre an end System Redundancy elimination service for enterprises
Networked Systems Design and Implementation, 2010Co-Authors: Bhavish Aggarwal, Aditya Akella, Ashok Anand, Athula Balachandran, Pushkar Chitnis, Chitra Muthukrishnan, Ramachandran Ramjee, George VargheseAbstract:In many enterprises today, WAN optimizers are being deployed in order to eliminate Redundancy in network traffic and reduce WAN access costs. In this paper, we present the design and implementation of EndRE, an alternate approach where Redundancy elimination (RE) is provided as an end System service. Unlike middleboxes, such an approach benefits both end-to-end encrypted traffic as well as traffic on last-hop wireless links to mobile devices. EndRE needs to be fast, adaptive and parsimonious in memory usage in order to opportunistically leverage resources on end hosts. Thus, we design a new fingerprinting scheme called SampleByte that is much faster than Rabin fingerprinting while delivering similar compression gains. Unlike Rabin fingerprinting, SampleByte can also adapt its CPU usage depending on server load. Further, we introduce optimizations to reduce server memory footprint by 33-75% compared to prior approaches. Using several terabytes of network traffic traces from 11 enterprise sites, testbed experiments and a pilot deployment, we show that EndRE delivers 26% bandwidth savings on average, processes payloads at speeds of 1.5- 4Gbps, reduces end-to-end latencies by up to 30%, and translates bandwidth savings into equivalent energy savings on mobile smartphones.
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NSDI - EndRE: an end-System Redundancy elimination service for enterprises
2010Co-Authors: Bhavish Aggarwal, Aditya Akella, Ashok Anand, Athula Balachandran, Pushkar Chitnis, Chitra Muthukrishnan, Ramachandran Ramjee, George VargheseAbstract:In many enterprises today, WAN optimizers are being deployed in order to eliminate Redundancy in network traffic and reduce WAN access costs. In this paper, we present the design and implementation of EndRE, an alternate approach where Redundancy elimination (RE) is provided as an end System service. Unlike middleboxes, such an approach benefits both end-to-end encrypted traffic as well as traffic on last-hop wireless links to mobile devices. EndRE needs to be fast, adaptive and parsimonious in memory usage in order to opportunistically leverage resources on end hosts. Thus, we design a new fingerprinting scheme called SampleByte that is much faster than Rabin fingerprinting while delivering similar compression gains. Unlike Rabin fingerprinting, SampleByte can also adapt its CPU usage depending on server load. Further, we introduce optimizations to reduce server memory footprint by 33-75% compared to prior approaches. Using several terabytes of network traffic traces from 11 enterprise sites, testbed experiments and a pilot deployment, we show that EndRE delivers 26% bandwidth savings on average, processes payloads at speeds of 1.5- 4Gbps, reduces end-to-end latencies by up to 30%, and translates bandwidth savings into equivalent energy savings on mobile smartphones.
Fumitoshi Matsuno - One of the best experts on this subject based on the ideXlab platform.
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Experimental study of Redundant Snake Robot Based on Kinematic Model
Proceedings 2007 IEEE International Conference on Robotics and Automation, 2007Co-Authors: Motoyasu Tanaka, Fumitoshi MatsunoAbstract:In this paper we consider modeling and control of a redundant snake robot with wheeled link mechanism based on kinematic model. We derive a kinematic model of a snake robot with introducing links without wheels and shape controllable points in the snake robot's body in order to make the System Redundancy controllable. By using Redundancy, it becomes possible to accomplish the main objective of controlling the position and the attitude of the snake robot head and the shape of the snake robot, and the sub-objective of the singular configuration avoidance. Simulations and experimental results show the validity of the control law and how snake robots move at the neighborhood of the singular configuration.
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Control of redundant 3D snake robot based on kinematic model
2003 IEEE International Conference on Robotics and Automation (Cat. No.03CH37422), 2003Co-Authors: Fumitoshi Matsuno, Kazu SuenagaAbstract:In this paper, we derive a kinematic model and a control law for 3D snake robots which have wheeled link mechanism. We define the Redundancy controllable System and find that introduction of links without wheels makes the System Redundancy controllable. Using Redundancy, it becomes possible to accomplish both main objective of controlling the position and the posture of the snake robot head, and sub-objective of the singular configuration avoidance. Computer simulations demonstrate the effectiveness of the proposed control law.
Benjamin J. Blalock - One of the best experts on this subject based on the ideXlab platform.
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SiC based current source rectifier paralleling and circulating current suppression
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, 2013Co-Authors: Fan Xu, Ben Guo, Zhuxian Xu, Fred Wang, Laren M. Tolbert, Benjamin J. BlalockAbstract:This paper develops a liquid cooled high efficiency three-phase current source rectifier (CSR) for data center power supplies based on 400 V-dc architecture, using SiC MOSFETs and Schottky diodes. The 98.54% efficiency is achieved at full load. The rectifiers are paralleled to achieve high power ratings and System Redundancy. The current balance and hot-swap of paralleled CSRs are realized in simulation using master-slave control. Moreover, an improved modulation scheme through adjustment of the freewheeling state is proposed and verified to effectively suppress the circulating current.
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DC-link current control scheme for paralleled three-phase current source rectifiers in high efficiency power supply System
2013 IEEE Energy Conversion Congress and Exposition, 2013Co-Authors: Fan Xu, Zhuxian Xu, Fred Wang, Leon M. Tolbert, Benjamin J. BlalockAbstract:Three-phase current source rectifier (CSR) is a promising solution for power supply Systems as the buck-type power factor correction converter. By converter paralleling, high power rating and System Redundancy can be achieved. However, asymmetrical distribution of load current among converter modules may occur, which can increase power loss or even damage devices. This paper presents the DC-link current control scheme for paralleled current source rectifiers to balance the output currents. Using a master-slave control, the balanced output current distribution and System Redundancy are implemented. By correcting zero state duration based on modulation scheme, the circulating current is suppressed without introducing additional power losses, and both positive and negative DC-link currents are balanced.
