Incorporating Right Half-Plane Poles and Zeros in a Frequency Domain Design Technique

1994 ◽  
Vol 116 (4) ◽  
pp. 593-601 ◽  
Author(s):  
Massoud Sobhani ◽  
Suhada Jayasuriya
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Design Methodology ◽  
Minimum Phase ◽  
Phase Problem ◽  
Nonminimum Phase ◽  
Phase Loop ◽  
Poles And Zeros ◽  
Bounded Disturbance ◽  
Domain Constraints

The frequency domain design methodology developed in Jayasuriya and Franchek (1988) for the synthesis of controllers that maximize the allowable size of an unknown-but-bounded disturbance in the presence of several time domain constraints is revisited. It is shown that (i) the basic ingredients of the methodology stays essentially the same for systems with nonminimum phase zeros and/or unstable poles, and (ii) two modifications can facilitate the loop shaping step. In particular, a nonminimum phase problem may be converted to one of frequency shaping a minimum phase loop; and a prestabilization scheme may be used for unstable systems. Two examples illustrate the proposed modifications with one compared to results obtained by the so called Set-Theoretic (ST) approach.

DESIGN OF RECURSIVE FILTERS

Geophysics ◽  
1970 ◽  
Vol 35 (2) ◽  
pp. 247-253 ◽  
Author(s):  
Raymundo Aguilera ◽  
J. CL. Debremaecker ◽  
Salvador Hernandez
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Minimum Phase ◽  
Recursive Filter ◽  
Recursive Filters ◽  
The Time Domain

Recursive filters are inherently more efficient than purely transverse or purely regressive ones. They can be computed in the frequency domain by a series of simple operations. The roots of the denominator must be computed and the moduli less than unity replaced by their inverses. If such an operation is also performed on the numerator, the resultant recursive filter is minimum phase. The same method can be used to construct a deconvolution operator in the time domain, starting with the autocorrelation. Two examples are given which show the efficiency of the method.

Frequency Domain Design for Maximizing the Allowable Size of a Step Disturbance in Linear Uncertain Systems

1994 ◽  
Vol 116 (4) ◽  
pp. 635-642
Author(s):  
Suhada Jayasuriya ◽  
Massoud Sobhani
Keyword(s):  
Transfer Function ◽  
Frequency Domain ◽  
Time Domain ◽  
Design Procedure ◽  
Control Input ◽  
Low Frequencies ◽  
Loop Shaping ◽  
Loop Transfer Function ◽  
Step Disturbance ◽  
Domain Constraints

A design methodology is developed for a linear, uncertain, SISO system for maximizing the size of a step disturbance in the presence of hard time domain constraints on system states, control input, output and the bandwidth. It is assumed that the system dynamics can be represented by a combination of structured uncertainty in the low frequencies and unstructured uncertainty in the high frequencies. The design procedure is based on mapping the time domain constraints into an equivalent set of frequency domain constraints which are then used to determine an allowed design region for the nominal loop transfer function in the plane of amplitude-phase. Once such a region is found, classical loop shaping determines a suitable nominal loop transfer function. The pole-zero structure of the compensator is a natural consequence of loop shaping and is not preconceived. An illustrative example demonstrates the trade-off between controller bandwidth, or the cost of feedback, and the tolerable size of step disturbance.

The Application of Response Based Design in the Verification of the Banff Riser System

2002 ◽  
Author(s):  
David McCann ◽  
Keith Anderson ◽  
Thomas S. Taylor ◽  
Patrick O’Brien
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Design Methodology ◽  
Linear Time ◽  
Frequency Content ◽  
Method Of Solution ◽  
Stochastic Techniques ◽  
Computationally Expensive ◽  
Frequency Domain Approach ◽  
Dynamic Frequency

This paper details work that was conducted during the retrieval and subsequent re-installation of the Banff riser system between September 2000 and March 2001. Originally, deterministic methods were used to design the riser system. It is demonstrated that these methods may not be conservative when compared against stochastic techniques. To ensure a conservative design methodology it is necessary to fully account for the inherent dynamic frequency content of the riser. This is usually achieved using non-linear time domain irregular sea techniques. Time domain irregular sea analysis is computationally expensive in terms of resources and time. This paper presents the results of an alternative method of solution based on the frequency domain approach. Excellent agreement between the results of the time and frequency domain is observed.

Modeling of attenuation and dispersion

Geophysics ◽  
1993 ◽  
Vol 58 (8) ◽  
pp. 1167-1173 ◽  
Author(s):  
Carlos Lopo Varela ◽  
Andre L. R. Rosa ◽  
Tadeusz J. Ulrych
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Low Cost ◽  
Real Data ◽  
Dispersion Modeling ◽  
Minimum Phase ◽  
The Time Domain ◽  
Wavefield Extrapolation ◽  
Attenuation And Dispersion ◽  
Proper Solutions

At the present time, proper solutions for absorption modeling are based on wavefield extrapolation techniques which, in some instances, may be considered expensive. Two alternative, low cost, but incomplete solutions exist in the literature. The first models dispersion in the frequency domain in accordance with the Futterman dispersive relations but does not consider attenuation. The second models both attenuation and dispersion in the time domain but assumes a digital minimum‐phase formulation that results in an inadequate treatment of the dispersion. We show that this second solution can be adapted to perform attenuation and/or dispersion modeling in agreement with the Futterman attenuation‐dispersion relationships thus obviating the shortcoming mentioned above. Synthetic and real data examples are shown to illustrate the performance of the proposed algorithm.

Robust Nondiagonal Controller Design for Uncertain Multivariable Regulating Systems

1997 ◽  
Vol 119 (1) ◽  
pp. 80-85 ◽  
Author(s):  
M. A. Franchek ◽  
P. Herman ◽  
O. D. I. Nwokah
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Design Methodology ◽  
Controller Design ◽  
Parametric Uncertainty ◽  
Specific Class ◽  
Loop Design ◽  
Hard Time ◽  
System Integrity ◽  
Frequency Domain Approach

Presented in this paper is a robust controller design methodology for a class of uncertain, multivariable, regulating systems required to maintain a prespecified operating condition within hard time domain tolerances despite a vector of step disturbances. The design methodology is a frequency domain approach and is based on sequential loop design where a Gauss elimination technique facilitates the various design steps. The specific class of systems addressed are those which can be modeled as square, multivariable systems with parametric uncertainty. One restriction imposed is that the system and its inverse are stable for all plant parameter combinations. The key features of this design methodology include (i) the design of a fully populated controller matrix, (ii) the ability to design for system integrity, and (iii) the direct enforcement of hard time domain tolerances through frequency domain amplitude inequalities.

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

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