Influence Of Transmission Errors Research Articles

伝送エラーが電子ホログラフィの再生像へ与える影響

伝送エラーが電子ホログラフィの再生像へ与える影響

Theoretical and experimental investigation into the influence of the periodic backlash fluctuations on the gear rattle

The paper provides an investigation into the influence of the periodic variation in the boundaries of the dead-zone between the teeth, caused by the Transmission Error, on the gear rattle phenomenon. The study represents an evolution of a theoretical model, which has already been developed by the authors, to analyze lightly loaded gear pairs, accounting for oil squeeze effects between the gear teeth. An experimental test rig and a methodology to estimate the transmission error parameters, starting from an experimental acquisition, are described. A number of experimental–theoretical correlations concerning the influence of transmission errors on gear dynamics are reported in order to validate the theoretical model.

Torsional Vibration Effects on Induction Machine Current and Torque Signatures in Gearbox-Based Electromechanical System

The monitoring of heavy-duty electromechanical systems is crucial for their preventive maintenance planning. In these systems, the mechanical anomalies such as load troubles, great torque dynamic variations, and torsional oscillations lead to shaft fatigue and aging of other mechanical parts such as bearings and gearboxes. In this paper, a gearbox-based electromechanical system is investigated. Initially, a simple gearbox dynamic model is used to show the effects of rotating input, output, and mesh frequency components on the electromagnetic torque and consequently on the stator current signature. By this model, the influence of transmission error, eccentricities of pinion/wheel, and teeth contact stiffness variation is demonstrated for a healthy gearbox. Then, it is shown that the electrical machine can be considered as a torque sensor through electromagnetic torque estimation for torsional vibration monitoring without any extra mechanical sensor. A test-rig based on a 5.5-kW three-phase squirrel-cage induction motor connected to a wound-rotor 4-kW induction generator via a one-stage gearbox has been used to validate the proposed method.

Temporal Error Concealment for MPEG-Coded Video over Error-Prone Networks

Compressed video streams that transmitted over error prone networks may suffer severe degradation. Error concealment (EC) is one practical approach to combat with the error propagation. A number of EC techniques have been developed to diminish the influence of transmission errors. However, the techniques are always inefficient when the motions of object in a video are fast or complex. This paper proposes an adaptive temporal EC algorithm to precisely conceal the errors for MPEG-coded video. In the proposed method, each damaged macroblock is first divided into four equal sized sub-blocks. Both of the undamaged motion vectors and gray intensity information surrounding a damaged macroblock are performed to reconstruct the lost motion vectors of the sub-blocks based on boundary matching technique. Then the estimated motion vectors are utilized to reconstruct the damaged macroblock by exploiting the information from reference frames. Experimental results show that the visual quality and the PSNR evaluation of reconstructed frames are significantly improved by using the proposed EC algorithms. Thus the proposed method is expected to be a useful EC algorithm for motion vector compressed video over an error-prone network.

Distributed multilink system for very-high-speed data link control

A protocol control system architecture that provides very high processing performance for gigabit-per-second data communication in a broadband network is described. The architecture connects protocol controllers in parallel and uses a distributed multilink method that features a distributed algorithm for allocating transmission on the transmitting side and a resequencing algorithm on the receiving side. The system performance and the influence of transmission errors caused by cell loss in an asynchronous transfer mode network are evaluated. It is shown that by reducing each controller's distributing overhead, the system increases throughput up to 90 times that achieved when using a single controller.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Total vibrational excitation and transmission error of gears as index of vibration and noise of power transmissions.

Gear vibration is induced by the excitation due to manufacturing/alignment errors and periodical chasnge of meshing tooth stiffness with progress of gear rotation. As an index for evaluating the degree of gear vibration and noise as functions of gear dimensions, accuracy and driving conditions, transmission error of gears and total vibrational excitation are widely accepted. This report clarifies that the influence of transmission error and that of total vibrational excitation on gear vibration are equal in their first order frequency component, and the difference between them is due to the higher order frequency components of the periodical change of meshing tooth stiffness. The difference in the degree of influence of these two indices on the relative rotational vibration of gears is discussed using numerical examples. Propriety between both indices is also discussed to predict the actual gear noise of automotive power transmission of personal cars in production.

Efficient Coding and Speech Interpolation: Principles and Performance Characterization

The BPA (block priority assignment) system combines the principle of speech interpolation with waveform coding methods for the active speech signal. Coding with variable wordlength permits adapting the demand of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</tex> speech sources to the capacity of the channel. The system emphasized in this paper not only varies the bits per source according to the number of active talkers, but also assigns the number of bits to the source that needs it most based on estimates of the SNR over the block. When ADPCM and DSI are combined to give a 4:1 compression ratio over standard PCM (data rate 16 kbits/s) no distortions are audible. The influence of transmission errors and the use of various waveform coders is considered.