The work reports on studies, which supported the projecting, reconstruction and modification of a 750 kV, 479 km long transmission line. The changes were demanded by the technical development and the alteration of the...
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The work reports on studies, which supported the projecting, reconstruction and modification of a 750 kV, 479 km long transmission line. The changes were demanded by the technical development and the alteration of the role of the line in the power transmission. Authors analyse various ways for influencing on the interaction of the reactive power control, relaying and overvoltage protection. The possibility of the operation with incomplete, asymmetrical shunt reactor and arrester sets is investigated. The paper describes a simple way of controlled three-phase and adaptive single-phase reclosure.
In classical computer science any data that can be read can be copied an unlimited number of times. In the quantum world, the quantum states cannot be copied perfectly, according to the no-cloning theorem. The major d...
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In classical computer science any data that can be read can be copied an unlimited number of times. In the quantum world, the quantum states cannot be copied perfectly, according to the no-cloning theorem. The major difference between quantum and classical copy protection is the physical resource for data storage. The proposed quantum based data protection system lies in the fundamental difference between classical and quantum information. The classical data is stored in the secret rotation angles of non-orthogonal quantum states. In our paper we show that secret quantum decoding operations can be implemented with some associated error, which decreases exponentially with the number of quantum states of the angle state.
This paper reports advances in model based machine torque estimation used in electronic power assisted steering systems. Using machine input voltages the permanent magnet synchronous machine internal states and the ou...
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This paper reports advances in model based machine torque estimation used in electronic power assisted steering systems. Using machine input voltages the permanent magnet synchronous machine internal states and the output torque can be estimated. This technique can be used to detect machine failures and also can be used to verify the failure of the machine current measurement sensors.
The semiconductor optical amplifier (SOA) is a proper component for simultaneous modulation and amplification what is a good approach for sub-carrier multiplexed optical signal transmission. However, cascading several...
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The semiconductor optical amplifier (SOA) is a proper component for simultaneous modulation and amplification what is a good approach for sub-carrier multiplexed optical signal transmission. However, cascading several SOAs a new problem arises, an increase in the distortion due to cross-modulation of the different channels. In the paper an optimum approach is presented to overcome that distortion problem.
In the area of high voltages and powers, the high quality inverter-fed AC drive is more easily achieved by the use of three-level inverters. For three-level inverters three different PWM control regions can be introdu...
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In the area of high voltages and powers, the high quality inverter-fed AC drive is more easily achieved by the use of three-level inverters. For three-level inverters three different PWM control regions can be introduced where different two-phase (discontinuous) PWM strategies may be applied. This paper deals with the analysis of voltage spectra of one discontinuous PWM method of three-level inverters when every 30deg of each fundamental period the one motor phase is clamped to DC bar. The derivation of the analytical equations of motor voltage harmonics for this PWM method is given for both the realizations: with one and with two carrier waves. The comparison of the voltage spectra of the possible PWM methods is presented. It is shown that in the low voltage area the same value of motor harmonic losses are produced for both one and two carrier wave PWM. However, for the high voltage area the harmonic losses associated with the two carrier modulation are usually considerably lower than in case of one carrier method. The two carrier method can be disadvantageous only for low modulation frequency when the low order harmonics reach the sensitive value
Advanced information technology gives a new chance for new efficient forms of distance teaching and learning. In engineering, group work and computer descriptions are recent advancements in Internet based environments...
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Advanced information technology gives a new chance for new efficient forms of distance teaching and learning. In engineering, group work and computer descriptions are recent advancements in Internet based environments. Application of ideas and methods from computer aided engineering in distance teaching and learning is a new chance for fulfilling the old demand of integrated higher engineering education and industrial engineering environments. In this paper, flexible functionality of a new development in this area is analyzed. Following this, a student requests driven solution is discussed. Next structural and implementation issues are concluded.
Web-based software systems access some resources while executing the requests of the clients, typically several requests arrive at the same time, thus, competitive situation is established for the resources. In case o...
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Web-based software systems access some resources while executing the requests of the clients, typically several requests arrive at the same time, thus, competitive situation is established for the resources. In case of modeling such situation queueing model-based approaches are widely recognized. In our work, novel models and algorithms have been proposed to model the queue limit performance factor. In addition, the computational time and complexity of the proposed algorithms have been provided. Moreover, it has been shown that the proposed models and algorithms can be applied to performance prediction of webbased software systems in *** environment. The goal of our work is to validate the proposed models and algorithms and to verify the correctness of performance prediction with performance measurements in *** environment. The results have shown that the proposed models and algorithms predict the performance metrics much more accurate than the original model and algorithm.
Retransmission based error recovery is not always applicable for multimedia applications; however it can be used if the transmission characteristics and network conditions are examined before. Retransmissions can be c...
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Retransmission based error recovery is not always applicable for multimedia applications; however it can be used if the transmission characteristics and network conditions are examined before. Retransmissions can be carried out only if there is no congestion in the network and the network delay is low enough to receive the retransmitted packet before the playout. These two attributes are depending and one can be estimated from the other. In this paper we introduce a TFRC and RTT threshold interdependence model to determinate network delay thresholds for the retransmission decision algorithm. Using the calculated sending rate of the TFRC (TCP Friendly Rate Control) to estimate the congestion level in the network, we can set up a threshold of disabling/enabling the retransmissions. Our goal was to determinate a matching RTT threshold to gain similar retransmission behavior as using the sending rate threshold. We found that using our threshold estimating model, the number of retransmitted packets was similar, using the TFRC-based sending rate threshold and the RTT retransmission threshold.
The paper presents the testbed of a novel network architecture which aims at providing streaming media services in a heterogeneous environment where the subscribers are roaming among different wired/wireless access ne...
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The paper presents the testbed of a novel network architecture which aims at providing streaming media services in a heterogeneous environment where the subscribers are roaming among different wired/wireless access networks including ADSL, WiFi, 2.5G and 3G cellular and WiMAX. The architecture provides seamless connectivity during roaming, with adapting the quality of the delivered media stream to the changes of the network characteristics and to the capabilities of a wide variety of devices. The paper presents general design considerations, focuses on a novel vertical handover mechanism, its implementation and evaluation in the testbed, as well as discusses media processing aspects. The different subsystems are currently being integrated into a single testbed which will provide an open environment for experimentation and will be suitable for technology transfer to network service providers and content providers.
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