Xem 1-20 trên 55 kết quả Synchronous machines
  • This chapter include all of the following content: Introduction to polyphase synchronous machines, synchronous – machine inductances and equivalent circuits, performance characteristics, effects of salient poles, power – angle characteristics of salient – pole machines, permanent – magnet ac motors.

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  • The purpose of these notes is be used to introduce Electrical Engineering students to Electrical Machines, Power Electronics and Electrical Drives. They are primarily to serve our students at MSU: they come to the course on Energy Conversion and Power Electronics with a solid background in Electric Circuits and Electromagnetics, and many want to acquire a basic working knowledge of the material, but plan a career in a different area (venturing as far as computer or mechanical engineering).

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  • (BQ) he objective of Ebook Electrical machine is to study the devices used in the interconversion of electric and mechanical energy. Emphasis is placed on electromagnetic t rotating machinery, by means of which the bulk of this energy conversion takes place.

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  • Flux and Voltage Induction Machines 6.1 Description 6.2 Concept of Operation 6.3 Torque Development 6.4 Operation of the Induction Machine near Synchronous Speed 6.5 Leakage Inductances and their Effects 6.6 Operating characteristics 6.7 Starting of Induction Motors 6.8 Multiple pole pairs Synchronous Machines and Drives 7.1 Design and Principle of Operation 7.1.1 Wound Rotor Carrying DC 7.1.2 Permanent Magnet Rotor 7.2 Equivalent Circuit 7.3 Operation of the Machine Connected to a Bus of Constant Voltage and Frequency 7.4 Operation from a Source of Variable Frequency and Voltage...

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  • Synchronous machines come in a variety of different constructions and designs. The differences occur in the physical outlay of the rotor and in the way in which excitation flux is provided (if it is provided at all) in the machine. Regardless of the type however, all the synchronous machines have the same construction of the stator. Stator is of cylindrical crosssection, manufactured from laminated sheets of steel, and it carries a three-phase winding that is supplied with (in the motor case) or that produces (in the generator case) a system of threephase voltages....

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  • A synchronous machine is an ac rotating machine whose speed under steady state condition is proportional to the frequency of the current in its armature. The magnetic field created by the armature currents rotates at the same speed as that created by the field current on the rotor, which is rotating at the synchronous speed, and a steady torque results. Synchronous machines are commonly used as generators especially for large power systems, such as turbine generators and hydroelectric generators in the grid power supply. ...

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  • This paper introduces a new analytical method for performing the output torque calculations of an interior permanent magnet synchronous motor (IPMSM) including both permanent magnet and reluctance torque components.

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  • From the principles of electrical engineering it is known that the 3-phase quantities of the 3-phase AC machines can be summarized to complex vectors. These vectors can be represented in Cartesian coordinate systems, which are particularly chosen to suitable render the physical relations of the machines. These are the field-orientated coordinate system for the 3- phase AC drive technology or the grid voltage orientated coordinate system for generator systems.

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  • Synchronous Mode Synchronous systems negotiate the connection at the data-link level before communication begins Basic synchronous systems will begins. synchronize two clocks before transmission. Asynchronous mode Asynchronous systems do not send separate information to indicate the encoding or clocking information. The receiver must decide the clocking of the signal on it's own. This means that the receiver must decide where to look in the signal stream to find ones and zeroes.

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  • We propose a novel technique of learning how to transform the source parse trees to improve the translation qualities of syntax-based translation models using synchronous context-free grammars. We transform the source tree phrasal structure into a set of simpler structures, expose such decisions to the decoding process, and find the least expensive transformation operation to better model word reordering.

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  • Machine transliteration is defined as automatic phonetic translation of names across languages. In this paper, we propose synchronous adaptor grammar, a novel nonparametric Bayesian learning approach, for machine transliteration. This model provides a general framework without heuristic or restriction to automatically learn syllable equivalents between languages.

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  • Introduction to AC machine, synchronous generators, synchronous motors, three phase Induction machines, three phase induction motors, induction generators, induction regulators As the main contents of the document "Electrical machines 2". Invite you to consult the text book for more documents serving the academic needs and research.

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  • In this work we propose methods to label probabilistic synchronous context-free grammar (PSCFG) rules using only word tags, generated by either part-of-speech analysis or unsupervised word class induction. The proposals range from simple tag-combination schemes to a phrase clustering model that can incorporate an arbitrary number of features. Our models improve translation quality over the single generic label approach of Chiang (2005) and perform on par with the syntactically motivated approach from Zollmann and Venugopal (2006) on the NIST large Chineseto-English translation task. ...

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  • This paper presents the first empirical results to our knowledge on learning synchronous grammars that generate logical forms. Using statistical machine translation techniques, a semantic parser based on a synchronous context-free grammar augmented with λoperators is learned given a set of training sentences and their correct logical forms. The resulting parser is shown to be the bestperforming system so far in a database query domain.

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  • We present a statistical phrase-based translation model that uses hierarchical phrases— phrases that contain subphrases. The model is formally a synchronous context-free grammar but is learned from a bitext without any syntactic information. Thus it can be seen as a shift to the formal machinery of syntaxbased translation systems without any linguistic commitment. In our experiments using BLEU as a metric, the hierarchical phrasebased model achieves a relative improvement of 7.5% over Pharaoh, a state-of-the-art phrase-based system. ...

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  • Often one may wish to learn a tree-to-tree mapping, training it on unaligned pairs of trees, or on a mixture of trees and strings. Unlike previous statistical formalisms (limited to isomorphic trees), synchronous TSG allows local distortion of the tree topology. We reformulate it to permit dependency trees, and sketch EM/Viterbi algorithms for alignment, training, and decoding.

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  • This paper looks at representing paraphrases using the formalism of Synchronous TAGs; it looks particularly at comparisons with machine translation and the modifications it is necessary to make to Synchronous TAGs for paraphrasing. A more detailed version is in Dras (1997a).

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  • According to Dr. Goldratt, synchronous manufacturing refers to the entire production process working together in harmony to achieve the goals of the firm. Synchronous manufacturing logic attempts to coordinate all resources so that they work together and are in harmony or are "synchronized." The goal is on total system performance, not on localized measures such as labor or machine utilization.

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  • We take a multi-pass approach to machine translation decoding when using synchronous context-free grammars as the translation model and n-gram language models: the first pass uses a bigram language model, and the resulting parse forest is used in the second pass to guide search with a trigram language model. The trigram pass closes most of the performance gap between a bigram decoder and a much slower trigram decoder, but takes time that is insignificant in comparison to the bigram pass.

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  • Synchronous Tree-Adjoining Grammar (STAG) is a promising formalism for syntaxaware machine translation and simultaneous computation of natural-language syntax and semantics. Current research in both of these areas is actively pursuing its incorporation. However, STAG parsing is known to be NP-hard due to the potential for intertwined correspondences between the linked nonterminal symbols in the elementary structures.

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