نتایج جستجو برای: time varying frequency content

تعداد نتایج: 2686815  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه یزد 1390

the debate whether esp teachers need to have knowledge of the specialized field they are teaching has been an issue in the literature over the last two decades. the aim of conducting this study was to explore iranian learners’ and instructors’ beliefs and attitudes concerning the role of specialized knowledge in teaching esp classes. a seventeen item questionnaire was administered to 400 esp le...

Journal: :DEStech Transactions on Materials Science and Engineering 2017

2004
Henry L. Gray Chu-Ping C. Vijverberg Wayne A. Woodward

In this paper we discuss methodology for analyzing non-stationary time series whose periodic nature changes approximately linearly with time. We make use of the M-stationary process to describe such data sets, and in particular we use the discrete Euler(p) model to obtain forecasts and estimate the spectral characteristics. We discuss the use of the M-spectrum for displaying linear time-varying...

2002
J. P. Conte

Discrete time-varying autoregressive moving average (ARMA) models are used to describe realistic earthquake ground motion time histories. Both amplitude and frequency nonstationarities are incorporated in the model. An iterative Kalman filtering scheme is introduced to identify the time-varying parameters of an ARMA model from an actual earthquake record. Several model verification tests are pe...

Journal: :EURASIP Journal on Advances in Signal Processing 2002

1997
Zhiruo Cao Ellen W. Zegura

An available bit rate (ABR) service allows applications to access a time-varying network capacity. In a basic ABR service, the available network capacity is divided \fairly" amongst active connections, without regard to the utility that each application derives from the bandwidth allocation. The goal of this paper is to improve both the global and individual utility obtained by applications usi...

The EVs battery has the ability to enhance the balance between the load demand and power generation units. The EV aggregators to manage the random behaviour of EV owners and increasing EVs participation in the ancillary services market are employed. The presence of aggregators could lead to time-varying delay in load frequency control (LFC) schemes. The effects of these delays must be considere...

Journal: :CoRR 2005
Scott T. Rickard Radu V. Balan H. Vincent Poor Sergio Verdú

Mobile communication channels are often modeled as linear time-varying filters or, equivalently, as time-frequency integral operators with finite support in time and frequency. Such a characterization inherently assumes the signals are narrowband and may not be appropriate for wideband signals. In this paper time-scale characterizations are examined that are useful in wideband time-varying chan...

2001
Tamer Kadous Ke Liu Akbar M. Sayeed

We introduce a new signaling scheme for timeand frequencyselective channels that is a generalization of Multi-Carrier Code Division Multiple Access (MC-CDMA) signaling used in slowly time-varying channels. The Fourier basis functions used in conventional MC-CDMA systems encounter temporal distortion in rapidly time-varying channels resulting in degraded performance. The proposed scheme transmit...

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