On Vibrational Stabilization of a Horizontal Pendulum

2016 ◽  
Author(s):  
Sevak Tahmasian ◽  
Farid Jafari ◽  
Craig A. Woolsey
Keyword(s):  
Translational Control ◽  
High Frequency ◽  
Small Neighborhood ◽  
Constraint Equation ◽  
High Amplitude ◽  
Geometric Interpretation ◽  
Vibrational Stabilization ◽  
Linear Damping ◽  
And Control ◽  
Horizontal Pendulum

This paper describes control design and stability analysis for a horizontal pendulum using translational control of the pivot. The system is a one-link mechanism subject to linear damping and moving in the horizontal plane. The goal is to drive the system to a desired configuration such that the system oscillates in an arbitrarily small neighborhood of that desired configuration. We consider two cases: prescribed displacement inputs and prescribed force inputs. The proposed control law has two parts, a proportional-derivative part for control of actuated coordinates, and a high-frequency, high-amplitude oscillatory forcing to control the motion of unactuated coordinate. The control system is a high-frequency, time-periodic system. Therefore we use averaging techniques to determine the necessary input amplitudes and control gains. We show that using a certain oscillatory input, the amplitudes of that input must follow a constraint equation. We discuss the geometric interpretation of constraint equation and stability conditions of the system. We also discuss the effects of damping and relative phase of the oscillatory inputs on the system and their physical and geometric interpretation.

Vibrational Control of a 2-Link Mechanism

2020 ◽  
Author(s):  
Zakia Ahmed ◽  
Sevak Tahmasian ◽  
Craig A. Woolsey
Keyword(s):  
Translational Control ◽  
High Frequency ◽  
Horizontal Plane ◽  
High Amplitude ◽  
Torsional Stiffness ◽  
Physical Parameters ◽  
Vibrational Control ◽  
Link Mechanism ◽  
Torsional Damping ◽  
Fixed Input

Abstract This paper describes vibrational control and stability of a planar, horizontal 2-link mechanism using translational control of the base pivot. The system is a 3-DOF two-link mechanism that is subject to torsional damping, torsional stiffness, and is moving on a horizontal plane. The goal is to drive the averaged dynamics of the system to a desired configuration using a high-frequency, high-amplitude force applied at the base pivot. The desired configuration is achieved by applying an amplitude and angle of the input determined using the averaged dynamics of the system. We find the range of stable configurations that can be achieved by the system by changing the amplitude of the oscillations for a fixed input angle and oscillation frequency. The effects of varying the physical parameters on the achievable stable configurations are studied. Stability analysis of the system is performed using two methods: the averaged dynamics and averaged potential.

Case study: Simulation and control of high frequency noise for commercial vehicle cab considering leak

2019 ◽  
Vol 67 (4) ◽  
pp. 315-329
Author(s):  
Rongjiang Tang ◽  
Zhe Tong ◽  
Weiguang Zheng ◽  
Shenfang Li ◽  
Li Huang
Keyword(s):  
High Frequency ◽  
Commercial Vehicle ◽  
Frequency Noise ◽  
High Frequency Noise ◽  
Simulation And Control ◽  
And Control

Testing of Sonic-Absorbent Panels’ Behavior in Open-Air Environment

2012 ◽  
Author(s):  
Petru A. Pop ◽  
Patricia A. Ungur ◽  
Liviu Lazar ◽  
Mircea Gordan ◽  
Florin M. Marcu
Keyword(s):  
High Frequency ◽  
Noise Pollution ◽  
Sound Level ◽  
Sound Level Meter ◽  
Data Logger ◽  
Public Buildings ◽  
Gypsum Plaster ◽  
Level Meter ◽  
And Control

One wildly used method to reduce and control the noise pollution in green city’s buildings is using sonic-absorbent panels. Their applications can be multiple, such as the insulation of buildings, acoustic barriers and fences along the highway or in front of supermarkets, hospitals and other public buildings. This paper presents a method for testing the behavior of sonic-absorbent panels in open-air environment. The work represents a carrying on of previous research about absorbent materials from gypsum family, tested in lab conditions. The experiment setup used a dynamic installation and as a sample a stand formed by six sonic-absorbent panels from special modeling alpha-gypsum plaster. This installation has been composed of two loudspeakers for emitting the sound at a well-defined frequency by the first laptop, the microphone for detecting and transmitting the signal to the second laptop for analyzing and processing the data. All operations were performed using MATLAB Programs, while a Data Logger Sound Level Meter type CENTER 332 was put on near the microphone to compare both results. The first experiment of acoustic stand has been realized by setting up the installation at a frequency from 50 Hz to 1250 Hz and altering the distance between loudspeakers and stand at 0.5m to 1m and 1.5m, respectively. The second experiment kept the same test’s conditions, while two and three layers of sonic-absorbent panels formed the stand, respectively, but at same distance from source of 0.5 m. In both tests, the results underlined the good sonic-absorbent properties of these panels, especially at medium and high frequency, which can recommend using the panels for multiple outside applications.

Rate-dependent shortening of action potential duration increases ventricular vulnerability in failing rabbit heart

2011 ◽  
Vol 300 (2) ◽  
pp. H565-H573 ◽  
Author(s):  
Masahide Harada ◽  
Yukiomi Tsuji ◽  
Yuko S. Ishiguro ◽  
Hiroki Takanari ◽  
Yusuke Okuno ◽  
...  
Keyword(s):  
Action Potential ◽  
High Frequency ◽  
Rabbit Heart ◽  
Left Ventricular ◽  
High Frequency Stimulation ◽  
Electrophysiological Properties ◽  
Rate Dependent ◽  
Frequency Stimulation ◽  
And Control

Congestive heart failure (CHF) predisposes to ventricular fibrillation (VF) in association with electrical remodeling of the ventricle. However, much remains unknown about the rate-dependent electrophysiological properties in a failing heart. Action potential properties in the left ventricular subepicardial muscles during dynamic pacing were examined with optical mapping in pacing-induced CHF ( n = 18) and control ( n = 17) rabbit hearts perfused in vitro. Action potential durations (APDs) in CHF were significantly longer than those observed for controls at basic cycle lengths (BCLs) >1,000 ms but significantly shorter at BCLs <400 ms. Spatial APD dispersions were significantly increased in CHF versus control (by 17–81%), and conduction velocity was significantly decreased in CHF (by 6–20%). In both groups, high-frequency stimulation (BCLs <150 ms) always caused spatial APD alternans; spatially concordant alternans and spatially discordant alternans (SDA) were induced at 60% and 40% in control, respectively, whereas 18% and 82% in CHF. SDA in CHF caused wavebreaks followed by reentrant excitations, giving rise to VF. Incidence of ventricular tachycardia/VFs elicited by high-frequency dynamic pacing (BCLs <150 ms) was significantly higher in CHF versus control (93% vs. 20%). In CHF, left ventricular subepicardial muscles show significant APD shortenings at short BCLs favoring reentry formations following wavebreaks in association with SDA. High-frequency excitation itself may increase the vulnerability to VF in CHF.

scholarly journals High-Amplitude Circadian Rhythms inDrosophilaDriven by Calcineurin-Mediated Post-translational Control ofsarah

Genetics ◽  
2018 ◽  
pp. genetics.300808.2018 ◽  
Author(s):  
Sin Ho Kweon ◽  
Jongbin Lee ◽  
Chunghun Lim ◽  
Joonho Choe
Keyword(s):  
Circadian Rhythms ◽  
Translational Control ◽  
High Amplitude

scholarly journals Flame response to high-frequency oscillations in a cryogenic oxygen/hydrogen rocket combustor

2019 ◽  
Author(s):  
N. Fdida ◽  
J. Hardi ◽  
H. Kawashima ◽  
B. Knapp ◽  
M. Oschwald ◽  
...  
Keyword(s):  
High Frequency ◽  
Acoustic Resonance ◽  
High Amplitude ◽  
Operating Conditions ◽  
Test Facility ◽  
Response Analysis ◽  
Rocket Engines ◽  
Acoustic Oscillations ◽  
Spatially Resolved ◽  
Flame Response

Experiments presented in this paper were conducted with the BKH rocket combustor at the European Research and Technology Test Facility P8, located at DLR Lampoldshausen. This combustor is dedicated to study the effects of high magnitude instabilities on oxygen/hydrogen flames, created by forcing high-frequency (HF) acoustic resonance of the combustion chamber. This work addresses the need for highly temporally and spatially resolved visualization data, in operating conditions representative of real rocket engines, to better understand the flame response to high amplitude acoustic oscillations. By combining ONERA and DLR materials and techniques, the optical setup of this experiment has been improved to enhance the existing database with more highly resolved OH* imaging to allow detailed response analysis of the flame. OH* imaging is complemented with simultaneous visible imaging and compared to each other here for their ability to capture flame dynamics.

scholarly journals Ten-Year Follow-Up of Clinical Governance Implementation in Primary Care: Improving Screening, Diagnosis and Control of Cardiovascular Risk Factors

2019 ◽  
Vol 16 (21) ◽  
pp. 4299
Author(s):  
Carina Aguilar Martín ◽  
Alessandra Queiroga Gonçalves ◽  
Carlos López-Pablo ◽  
José Fernández-Sáez ◽  
Emma Forcadell Drago ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cardiovascular Risk ◽  
High Frequency ◽  
Cardiovascular Health ◽  
Density Lipoprotein ◽  
Health Indicators ◽  
Clinical Governance ◽  
And Control ◽  
The Impact

Current improvement strategies for the control of cardiovascular risk factors (CRFs) in Europe are based on quality management policies. With the aim of understanding the effect of interventions delivered by primary healthcare systems, we evaluated the impact of clinical governance on cardiovascular health after ten years of implementation in Catalonia. A cohort study that included 1878 patients was conducted in 19 primary care centres (PCCs). Audits that comprised 13 cardiovascular health indicators were performed and general practitioners received periodic (annual, biannual or monthly) feedback about their clinical practice. We evaluated improvement in screening, diagnosis and control of the main CRFs and the effects of the feedback on cardiovascular risk (CR), incidence of cardiovascular disease (CVD) and mortality, comparing baseline data with data at the end of the study (after a 10-year follow-up). The impact of the intervention was assessed globally and with respect to feedback frequency. General improvement was observed in screening, percentage of diagnoses and control of CRFs. At the end of the study, few clinically significant differences in CRFs were observed between groups. However, the reduction in CR was greater in the group receiving high frequency feedback, specifically in relation to smoking and control of diabetes and cholesterol (Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL)). A protective effect of having a cardiovascular event (hazard ratio (HR) = 0.64, 95% confidence interval (CI) = 0.44–0.94) or death (HR = 0.55, 95% CI = 0.35–0.88) was observed in patients from centres where general practitioners received high frequency feedback. Additionally, these PCCs presented improved cardiovascular health indicators and lower incidence and mortality by CVD, illustrating the impact of this intervention.

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