A Method of Model Reduction

1986 ◽  
Vol 108 (4) ◽  
pp. 368-371 ◽  
Author(s):  
Jium-Ming Lin ◽  
Kuang-Wei Han
Keyword(s):  
Transfer Function ◽  
Frequency Response ◽  
Model Reduction ◽  
Control Systems ◽  
Response Curve ◽  
Nonlinear Control Systems ◽  
Frequency Response Curve ◽  
Stability Boundaries ◽  
Parameter Variations ◽  
The Stability

In this brief note, the effects of model reduction on the stability boundaries of control systems with parameter variations, and the limit-cycle characteristics of nonlinear control systems are investigated. In order to reduce these effects, a method of model reduction is used which can approximate the original transfer function at S=0, S=∞, and also match some selected points on the frequency response curve of the original transfer function. Examples are given, and comparisons with the methods given in current literature are made.

Systems analysis of cerebrovascular pressure transmission: an observational study in head-injured patients

1990 ◽  
Vol 73 (6) ◽  
pp. 871-880 ◽  
Author(s):  
Ian R. Piper ◽  
J. Douglas Miller ◽  
N. Mark Dearden ◽  
James R. S. Leggate ◽  
Ian Robertson
Keyword(s):  
Transfer Function ◽  
Frequency Response ◽  
Response Curve ◽  
Frequency Response Curve ◽  
Content Type ◽  
High Frequency Response ◽  
Curve Type ◽  
Head Injured ◽  
Pressure Transmission ◽  
Injured Patients

✓ In an observational study in head-injured patients, cerebrovascular pressure transmission was investigated using a systems analysis approach whereby the blood pressure (BP) waveform was used as a measure of an input stimulus to the cerebrovascular bed (CVB) and the intracranial pressure (ICP) waveform as the response to that stimulus. The transfer function is a measure of how much pressure is transmitted through the CVB at a given frequency and is calculated using Fourier analysis of the pressure waveforms. The transfer function allows quantification of the pressure transmission performance of the CVB, thus providing a basis for comparison between normal and abnormal function. Fifteen hundred samples of ICP and BP waveforms were collected from 30 head-injured patients via microcomputer. Off-line spectral analysis of the waveform database revealed four main classes of transfer function: those with an overall flat transfer function (curve type 1); those with an elevated low-frequency response (curve type 2); those with an elevated high-frequency response (curve type 3); and those exhibiting both an elevated low- and high-frequency response (curve type 4). Curve types 2 and 4 were most often associated with raised ICP (> 20 mm Hg), whereas curve types 1 and 3 were most often affiliated with ICP less than 15 mm Hg. Studies of this type may provide insight into the pathophysiology of the CVB and ultimately aid in the prediction and treatment of raised ICP.

scholarly journals Vibrational Analysis of Composite Beam Embedded with Nitinol Shape Memory Alloy Wires

2018 ◽  
Vol 7 (3.4) ◽  
pp. 143
Author(s):  
Omer Muwafaq Mohmmed Ali ◽  
Rawaa Hamid Mohammed Al-Kalali ◽  
Ethar Mohamed Mahdi Mubarak
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Frequency Response ◽  
Response Curve ◽  
Natural Frequencies ◽  
Damping Ratio ◽  
Vibrational Analysis ◽  
Laminated Composite ◽  
Vibration Modes ◽  
Frequency Response Curve

In this paper, laminated composite materials were hybridized with fibers (E-glass) and shape memory alloy wires which considered a smart material. The effect of changing frequency on the (acceleration- frequency) response curve, the damping ratio of the vibration modes, the natural frequencies of the vibration mode, the effect of shape memory alloy wires number on the damping characteristics were studied. Hand lay-up technique was used to prepare the specimens, epoxy resin type was used as a matrix reinforced by fiber, E-glass. The specimens were manufactured by stacking 2 layers of fibers. Shape memory alloy, type Nitinol (nickel-titanium) having a diameter (1 and 2mm), was used to manufacture the specimens by embedding (1,2 and 3) wires into epoxy. Experimentally, the acceleration- frequency response curve was plotted for the vibration modes, this curve was used to measure the natural frequencies of the vibration modes and calculate the damping ratio of the vibration modes. ANSYS 15- APDL was used to determine the mode shape and find the natural frequencies of the vibration modes then compared with the experimental results. The results illustrated that, for all specimens increasing the natural frequency leads to decreasing the damping ratio. Increasing the number of shape memory alloy wires leads to increase the values of the damping ratio of the vibration modes and the natural frequencies of the vibration modes at room temperature. 

An Analysis of the Galvanometer Amplifier and its Response to Alternating Electromotive Forces and Mechanical Vibrations

1951 ◽  
Vol 4 (4) ◽  
pp. 560
Author(s):  
RG Wylie ◽  
AFA Harper
Keyword(s):  
Frequency Response ◽  
Response Curve ◽  
Mechanical Vibration ◽  
Frequency Response Curve ◽  
Mechanical Vibrations ◽  
Frequency Axis ◽  
Critical Damping

A system which is representative of most practical galvanometer amplifiers is analysed and the response of the system to alternating e.m.f.'s and to mechanical vibration is determined. It is shown that the values of the circuit constants can be so chosen that the galvanometer movement is at least critically damped for all conditions of operation and that, for critical damping. the frequency response curve for the amplifier to applied alternating e.m.f.'s resembles that for the galvanometer alone but is expanded along the frequency axis by a factor which depends on the degree of feedback. Mechanical vibration with a component about the axis of the galvanometer cod produces an effect which is markedly increased by the provision of feedback.

scholarly journals Comparison of the gain calculated from the frequency response curve in a hearing aid and the functional gain

2011 ◽  
Vol 54 (2) ◽  
pp. 118-122
Author(s):  
Yuka Yoshida ◽  
Tadashi Nishimura ◽  
Fumi Fukuda ◽  
Osamu Saito ◽  
Hiroshi Hosoi
Keyword(s):  
Frequency Response ◽  
Response Curve ◽  
Hearing Aid ◽  
Frequency Response Curve ◽  
Functional Gain

Transmitter interactions in rabbit internal anal sphincter

1995 ◽  
Vol 269 (2) ◽  
pp. G232-G239 ◽  
Author(s):  
M. A. Knudsen ◽  
E. B. Glavind ◽  
A. Tottrup
Keyword(s):  
Frequency Response ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Response Curve ◽  
Isometric Tension ◽  
Relative Importance ◽  
Frequency Response Curve ◽  
Cholinergic Nerves ◽  
Impulse Duration ◽  
The Right

The aim of the present study was to investigate the relative importance of the different putative nonadrenergic noncholinergic (NANC) mediators and their interplay with cholinergic nerves in the rabbit internal anal sphincter (IAS). IAS preparations were mounted in organ baths for recording of isometric tension. Transmural field stimulation (TMS; 5-s trains; supramaximal voltage, 140-160 V; 0.4-ms impulse duration) was applied every 2 min with frequencies varying from 0.2 to 32 Hz. TMS induced frequency-dependent relaxations that amounted to 89.3 +/- 2.2% (n = 7). N omega-nitro-L-arginine (L-NNA; 10(-7)-10(-4) M; 8 Hz) reduced relaxations and this effect was partially inhibited by preincubation with L-arginine (10(-4) M). The effect of L-NNA was attenuated by atropine preincubation. Apamin (10(-6) M) shifted the frequency-response curve to the right but left maximal relaxations in response to TMS unaffected. In the presence of L-NNA (10(-4) M) and atropine (10(-6) M), the action (area between the frequency-response curve with or without a substance) of apamin was more pronounced, but, despite the presence of both L-NNA and apamin, some relaxation still remained. The frequency-response curve (control) was significantly shifted to the right by carbachol (10(-6) M). Concentration-response experiments showed that the response to exogenous nitric oxide (NO; 10(-7)-10(-4) M) was unaffected by carbachol (10(-6) M) preincubation, whereas responses to vasoactive intestinal polypeptide (VIP) and ATP were significantly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

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