This paper discusses the control of the compensation voltages in dynamic voltage restorers (DVR). On analyzing the power circuit of a DVR system, control limitations and control targets are presented for the compensat...
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This paper discusses the control of the compensation voltages in dynamic voltage restorers (DVR). On analyzing the power circuit of a DVR system, control limitations and control targets are presented for the compensation voltage control. Based on the preceeded power stage analysis, a novel controller for the compensation voltages in DVRs is proposed by a feedforward control sch.me. This paper also discusses the time delay problems in the control system of DVRs. Digital control systems inevitably have control delay due to its the sampling of signal, the switching frequency of an inverter, and the signal delay due to sensor itself. The total signal delay is considerable in real implementation and it endanger the system stablity. This paper analyzes the relationship among the control delay, closed loop damping factor, and the output filter parameters of DVR inverters. Based on the control system analysis, a guideline is proposed to design the appropriate output filter parameters and the inverter switching frequency for DVRs. The proposed theory is verified by an experimental DVR system, which is controlled in full digital manner.
It is known that parallel type mechanisms have many singularities than serial type mechanisms. In haptic application, these singularities deteriorate the force reflecting performance. Moreover, different from general ...
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It is known that parallel type mechanisms have many singularities than serial type mechanisms. In haptic application, these singularities deteriorate the force reflecting performance. Moreover, different from general manipulators, haptic systems can't avoid the singular point, because they are operated by the user's random motion command. Although many singularity-free load distribution algorithms for kinematically redundant manipulators have been proposed, singularity-free load distribution algorithms for parallel haptic application have not been deeply discussed. In this paper, various singularity-free load distribution algorithms that are appropriate to parallel haptic system will be discussed. A new 6 DOF parallel mechanism equipped with four sub-chains is employed as a test device. To cope with singularity problem, four task-priority algorithms and redundant actuation algorithm are discussed and compared through simulation, and also experiments have been performed to show the effectiveness of those algorithms at the presence of singularity.
The final goal of this research is to develop a mobile system to collect 3-D information and panoramic image in rubble to search human bodies and situation in the rubble. This system has abilities to collect and deliv...
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ISBN:
(纸本)0780384636
The final goal of this research is to develop a mobile system to collect 3-D information and panoramic image in rubble to search human bodies and situation in the rubble. This system has abilities to collect and deliver infomation and cooperate with other robots etc. As a part of this project, multiple CMOS cameras are integrated in a sensor head, and software for generating panorama image and distance information is developed.
To provide network services consistently under various network failures, enterprise networks increasingly utilize path diversity through multi-homing. As a result, multi-homed non-transit autonomous systems (ASes) bec...
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To provide network services consistently under various network failures, enterprise networks increasingly utilize path diversity through multi-homing. As a result, multi-homed non-transit autonomous systems (ASes) become to surpass single-homed networks in number. In this paper, we address an inevitable problem that occurs when networks with multiple entry points deploy stateful inspection firewalls in their borders. In this paper, we formulate this phenomenon into a state-sharing problem among multiple firewalls under asymmetric routing condition. To solve this problem, we propose a stateful inspection protocol that requires very low processing and messaging overhead. Our protocol consists of the following two phases: 1) Generation of a TCP SYN cookie marked with the firewall identification number upon a SYN packet arrival, and 2) State sharing triggered by a SYN/ACK packet arrival in the absence of the trail of its intial SYN packet. We demonstrate that our protocol is scalable, robust, and simple enough to be deployed for high speed networks. It also transparently works under any client-server configurations. Last but not least, we present experimental results through a prototype implementation.
We propose a variational algorithm to jointly estimate the shape, albedo, and light configuration of a Lambertian scene from a collection of images taken from different vantage points. Our work can be thought of as ex...
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We propose a variational algorithm to jointly estimate the shape, albedo, and light configuration of a Lambertian scene from a collection of images taken from different vantage points. Our work can be thought of as extending classical multi-view stereo to cases where point correspondence cannot be established, or extending classical shape from shading to the case of multiple views with unknown light sources. We show that a first naive formalization of this problem yields algorithms that are numerically unstable, no matter how close the initialization is to the true geometry. We then propose a computational sch.me to overcome this problem, resulting in provably stable algorithms that converge to (local) minima of the cost functional. Although we restrict our attention to Lambertian objects with uniform albedo, extensions of our framework are conceivable.
This paper describes the application of symbolic techniques (in particular, OBDD's) to model checking specifications in the logic of knowledge for an agent operating with synchronous perfect recall in an environme...
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This paper describes the application of symbolic techniques (in particular, OBDD's) to model checking specifications in the logic of knowledge for an agent operating with synchronous perfect recall in an environment of which it has incomplete knowledge. It discusses the application of these techiques to the verification of a security protocol: Chaum's Dining Cryptographers protocol, which provides a mechanism for anonymous broadcast.
Uplink synchronous transmission has been proposed to improve the uplink capacity of DS-CDMA systems by means of canceling interference from the main paths of other intra-cell users. A significant capacity gain has bee...
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Uplink synchronous transmission has been proposed to improve the uplink capacity of DS-CDMA systems by means of canceling interference from the main paths of other intra-cell users. A significant capacity gain has been reported in a single cell environment. This Letter further investigates the uplink capacity in a multiple cell environment, where two crucial factors are taken into account, namely code shortage problem and soft handover. The impacts of the target E-b/I-o and the other-to-own cell interference ratio, together with the number of channelisation codes, are discussed mathematically and then, confirmed through system level simulations with more realistic parameters.
Dynamic voltage restorer (DVR)s are known as effective and economic means to compensate for voltage sags and swells [1]-[11], This paper proposes a novel method to generate reference waves synchronized with the grid w...
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Dynamic voltage restorer (DVR)s are known as effective and economic means to compensate for voltage sags and swells [1]-[11], This paper proposes a novel method to generate reference waves synchronized with the grid whether or not the line voltages are distorted by a fault. The proposed reference wave generator (RWG) looks for the normal voltage waveforms in the grid from the corrupted line voltages and synthesizes the expected positive sequence reference waves for DVRs. There is no transient problem on the generated reference waves when the line voltages are distorted by faults. Experimental results verified the proposed theory very well.
This paper presents the SERF (System for Electronic Recommendation Filtering) which is a collaborative filtering system that recommends context-sensitive, high-quality information sources for document search. Collabor...
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sch.duling has been extensively studied in various disciplines in operations research and wireline networking. However, the unique characteristics of wireless communication systems - namely, timing-varying channel con...
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ISBN:
(纸本)0780379543
sch.duling has been extensively studied in various disciplines in operations research and wireline networking. However, the unique characteristics of wireless communication systems - namely, timing-varying channel conditions and multi-user diversity - means that new sch.duling solutions need to be developed that are specifically tailored for this environment. In this paper, we summarize various opportunistic sch.duling sch.mes that exploit the time-varying nature of the radio environment to improve the spectrum efficiency while maintaining a certain level of satisfaction for each user. We also discuss the advantages and costs associated with opportunistic sch.duling, and identify possible future research directions.
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