Topic
Transfer function
About: Transfer function is a research topic. Over the lifetime, 14362 publications have been published within this topic receiving 214983 citations. The topic is also known as: system function & network function.
Papers published on a yearly basis
Papers
More filters
TL;DR: Analysis of the performance of systems recently proposed by various authors in which the received signal is Fourier transformed in real time and then filtered by a multiplication of the transformed signal by an appropriate transfer function is provided.
Abstract: This paper provides a detailed analysis of the performance of systems recently proposed by various authors in which the received signal is Fourier transformed in real time (usually with a surface acoustic wave device) and then filtered by a multiplication of the transformed signal by an appropriate transfer function. We shall refer to this operation as transform domain filtering. General expressions for the output waveforms of the system will be derived, and a specific example illustrating the performance of the system when operating in the presence of a narrow-band interferer plus additive white Gaussian noise will be presented. It will be shown that certain filtering techniques not feasible in conventional systems, such as filtering with ideal bandpass filters, become straightforward using transform domain filtering. Finally, a receiver will be described which will eliminate that intersymbol interference between adjacent data symbols due to filtering at the receiver.
105 citations
TL;DR: In this paper, the authors describe active attenuation of naturally occurring Tollmien-Schlichting (TS) instabilities on an unswept wing by superimposition with artificially generated counter waves in order to shift the laminar-turbulent transition downstream.
104 citations
TL;DR: Improvements are achieved by a more accurate modeling of the machine and the inverter, and the detrimental effects of conventional control methods are eliminated by forcing the harmonic components on an optimal spatial trajectory.
Abstract: Medium voltage AC machines fed by high-power inverters operate at a low switching frequency to restrain the switching losses of power semiconductor devices. Particular care is thus required in the design of the drive control system. The signal delay caused by low switching frequency operation increases undesired cross-coupling effects in vector-controlled schemes. These are not sufficiently compensated by established methods like feedforward control. Improvements are achieved by a more accurate modeling of the machine and the inverter. An adequate controller is introduced, having a transfer function with complex coefficients. The high harmonic distortion due to the low switching frequency is a tradeoff. Using synchronous optimal pulsewidth as an alternative permits reducing the switching frequency without increasing the harmonics. The detrimental effects of conventional control methods are eliminated by forcing the harmonic components on an optimal spatial trajectory. Deadbeat behavior and complete decoupling are thus achieved. The performance of the aforementioned schemes is compared based on mathematical analyses and experimental results.
104 citations
Book•
01 Jan 2001
TL;DR: In this paper, the authors present a survey of the state-of-the-art S&R models and their application in the space and frequency domain, including the Fourier series and Fourier transform.
Abstract: Introduction - Modeling Applications. Conceptual S&R Model. Performance Prediction Approaches. Surveillance and Reconnaissance Systems - Introduction. Imaging with IR and EO Sensors. Image Formation. Imaging System parameters. Synthetic Aperture Radar. Choice of Imaging Sensors. Examples of Surveillance and Reconnaissance Sensors. Historical Review of S&R Modeling - Pre-1950. 1950-1970. 1970-Present. Linear Shift Invariant Imaging Systems - Linearity and Shift Invariance. The Impulse Function. The Fourier Series and Fourier Transform. LSI Imaging System. Imaging in the Space and Frequency Domain. Imaging With Components. Simplifying LSI Imager Analysis to One Dimension. Sampled Imaging Systems. SAR Impulse Response and Transfer Function. Information Extraction Measures - Direct Performance Measures. Theory of Signal Detection. Range/Time Measures. Performance Estimate Measures. Information and Difference Metrics. Information Extraction Performance Predictors - Scale, Resolution, and Sharpness. Contrast and Noise. Artifacts. Summary Measures. Target and Environmental Considerations - Target Effects. Deception and Denial. Atmospheric Effects. Image Processing Considerations - Bandwidth Compression. Enhancement Processing. Display and Observer Considerations - Displays. Observer Characteristics. Observer Models. Performance Prediction Models - Parameter-based Models. Image-Based Models. Sensor Performance Conversions - Johnson Criteria and NIIRS. Conversion with Models. Comparing Sensor Performance Conversions. Performance Conversion as a Function of Target Size. Conclusions and Future Directions - Spectral Domain. Temporal Effects. Search. SAR.
104 citations
TL;DR: In this article, a transfer-function approach is developed for the class of linear time-varying discrete-time systems, specified in terms of skew (noncommutative) rings of polynomials and formal power series, both with coefficients in a ring of time functions.
Abstract: In the first part of the paper a transfer-function approach is developed for the class of linear time-varying discrete-time systems. The theory is specified in terms of skew (noncommutative) rings of polynomials and formal power series, both with coefficients in a ring of time functions. The transfer-function matrix is defined to be a matrix whose entries belong to a skew ring of formal power series. It is shown that various system properties, such as asymptotic stability, can be characterized in terms of the skew-ring framework. In the last part of the paper, the transfer-function framework is applied to the study of feedback control. New results are obtained on assignability of system dynamics by using dynamic output feedback and dynamic state feedback. The results are applied to the control of an armature-controlled do motor with a variable loading.
103 citations