scholarly journals Remarks on the Sommerfeld effect characterization in the wavelet domain

2018 ◽  
Vol 25 (1) ◽  
pp. 98-108 ◽  
Author(s):  
M. Varanis ◽  
J.M. Balthazar ◽  
A. Silva ◽  
A.G. Mereles ◽  
R. Pederiva
Keyword(s):  
Energy Source ◽  
Wavelet Transform ◽  
Mechanical System ◽  
Wavelet Packet ◽  
Mechanical Systems ◽  
Wavelet Domain ◽  
Sommerfeld Effect ◽  
Nonstationary Regime ◽  
Shear Building

In many applications in engineering, a mechanical system operates in the nonstationary regime, either partially of fully, creating the possibility to generate nonlinearities in them. Great efforts have been made to better understand and characterize these phenomena. One of several methods that are being used for the processing of signals of a nonstationary nature, as well as for the characterization of nonlinearities in mechanical systems, is the wavelet transform. A particular phenomenon that is seen in systems operating in the nonstationary regime is the Sommerfeld effect, which occurs due to the nonlinear interaction between a nonideal energy source and a mechanical system. This phenomenon can lead to high amplitudes of vibration for the system that in turn can cause damage in it. Therefore, this work presents an application of the continuous wavelet transform and the wavelet packet transform for the characterization of the Sommerfeld effect in mechanical systems where only the time response is at hand. Experimental procedures were performed where a nonideal energy source (an unbalanced DC motor) was used to excite (a) a portal frame and (b) a three-story shear-building. The results showed the effectiveness and the potential of the methods proposed.

Enrichment and characterization of an anaerobic methyl ethyl ketoxime degrading culture from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor

1998 ◽  
Vol 37 (4-5) ◽  
pp. 95-98 ◽  
Author(s):  
Nancy G. Love ◽  
Mary E. Rust ◽  
Kathy C. Terlesky
Keyword(s):  
Energy Source ◽  
Activated Sludge ◽  
Electron Acceptor ◽  
Sequencing Batch Reactor ◽  
Enrichment Culture ◽  
Batch Reactor ◽  
Nitrification Inhibitor ◽  
Time Frame ◽  
Methyl Ethyl

An anaerobic enrichment culture was developed from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor using methyl ethyl ketoxime (MEKO), a potent nitrification inhibitor, as the sole carbon and energy source in the absence of molecular oxygen and nitrate. The enrichment culture was gradually fed decreasing amounts of biogenic organic compounds and increasing concentrations of MEKO over 23 days until the cultures metabolized the oxime as the sole carbon source; the cultures were maintained for an additional 41 days on MEKO alone. Turbidity stabilized at approximately 100 mg/l total suspended solids. Growth on selective media plates confirmed that the microorganisms were utilizing the MEKO as the sole carbon and energy source. The time frame required for growth indicated that the kinetics for MEKO degradation are slow. A batch test indicated that dissolved organic carbon decreased at a rate comparable to MEKO consumption, while sulfate was not consumed. The nature of the electron acceptor in anaerobic MEKO metabolism is unclear, but it is hypothesized that the MEKO is hydrolyzed intracellularly to form methyl ethyl ketone and hydroxylamine which serve as electron donor and electron acceptor, respectively.

Use of Wavelet Packet Transform in Characterization of Surface Quality

2007 ◽  
Vol 46 (15) ◽  
pp. 5152-5158 ◽  
Author(s):  
J. Jay Liu ◽  
Daeyoun Kim ◽  
Chonghun Han
Keyword(s):  
Surface Quality ◽  
Wavelet Packet ◽  
Wavelet Packet Transform

The Control of Vibration Transmissibility Using an Electrodynamic Actuator –Close-Loop Solution

2013 ◽  
Vol 436 ◽  
pp. 166-173
Author(s):  
A. Mihaela Mîţiu ◽  
Daniel Constantin Comeagă ◽  
Octavian G. Donţu
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Mechanical System ◽  
Closed Loop ◽  
Mechanical Systems ◽  
Vibration Transmissibility ◽  
Technical Solutions ◽  
The Mathematical Model

In this paper are presented some aspects of transmissibility control of mechanical systems with 1 DOF so that the effects of vibration on their action to be minimized. Some technical solutions that can be used for this purpose is analyzed. Starting from the mathematical model of an electro-mechanical system with 1 DOF, are identified the parameters which influence the effectiveness of the transmissibility control system using an electrodynamic actuator who work in "closed loop".

Controlled Arming of Mechanical Systems Embedded into Embarked Electrical Systems

2014 ◽  
Vol 555 ◽  
pp. 209-216
Author(s):  
Gheorghe Negru
Keyword(s):  
Kalman Filter ◽  
Mechanical System ◽  
High Speed ◽  
Mechanical Systems ◽  
Electrical Systems ◽  
General Motion

The paper presents an application of the Kalman filter to achieve the controlled arming of mechanical system embedded into embarked electrical systems (FMES). The solution of FMES which contain mechanical subsystems electronically controlled could significantly reduce the influence, on their functioning, of the general motion of high speed object (HSO) .

The Method for Determining the Vibration-Damping Elements for the Mechanical System to Obtain the Desired Amplitude Value

2014 ◽  
Vol 657 ◽  
pp. 644-648 ◽  
Author(s):  
Andrzej Dymarek ◽  
Tomasz Dzitkowski
Keyword(s):  
Mechanical System ◽  
Dynamic Characteristics ◽  
Vibration Reduction ◽  
Mechanical Systems ◽  
Vibration Damping ◽  
Displacement Velocity ◽  
Synthesis Methods ◽  
Resonance Frequencies

The paper presents the use of synthesis methods to determine the parameters of passive vibration reduction in mechanical systems. Passive vibration reduction in a system is enabled by units called dampers whose values are determined on the basis of the method formulated and formalized by the authors. The essence of the method are, established at the beginning of a task, dynamic characteristics in the form of the resonance and anti-resonance frequencies, and amplitudes of displacement, velocity or acceleration of vibration.

CHARACTERIZATION OF IMAGE SPACE OF A WAVELET TRANSFORM

2006 ◽  
Vol 04 (03) ◽  
pp. 547-557 ◽  
Author(s):  
CAIXIA DENG ◽  
YULING QU ◽  
LIJUAN GU
Keyword(s):  
Wavelet Transform ◽  
Truncation Error ◽  
Reproducing Kernel ◽  
Reproducing Kernel Hilbert Space ◽  
Sampling Theorem ◽  
Image Space ◽  
Kernel Space ◽  
Reproducing Kernel Space ◽  
Scope Of Application

In this paper, Journe wavelet function is introduced as a wavelet generating function. The expression of reproducing kernel function for the image space of this wavelet transform is obtained based on the fact that the image space of the wavelet transform is a reproducing kernel Hilbert space. Then the isometric identity of Journe wavelet transform is obtained. The connections between the image space of the wavelet transform and the image space of the known reproducing kernel space are established by the theories of reproducing kernel. The properties and the structures of the image space of the wavelet transform can be characterized by the properties and the structures of the image space of the known reproducing kernel space. Using the ideas of reproducing kernel, we consider there are relations between the wavelet transform and the sampling theorem. Meanwhile, the approximations in sampling theorems is shown and the truncation error is given. This provides a theoretical basis for us to study the image space of the general wavelet transform and broadens the scope of application of theories of the reproducing kernel space.

Growth and Characterization of 3C-SiC Films for Micro Electro Mechanical Systems (MEMS) Applications

2009 ◽  
Vol 9 (11) ◽  
pp. 4852-4859 ◽  
Author(s):  
Matteo Bosi ◽  
Bernard E. Watts ◽  
Giovanni Attolini ◽  
Claudio Ferrari ◽  
Cesare Frigeri ◽  
...  
Keyword(s):  
Mechanical Systems ◽  
Micro Electro Mechanical Systems ◽  
Sic Films

COMPARISON BETWEEN DISCRETE AND PACKET WAVELET TRANSFORM ANALYSES IN THE STUDY OF HEARTBEAT CARDIAC SOUNDS

2007 ◽  
Vol 07 (02) ◽  
pp. 199-214 ◽  
Author(s):  
S. M. DEBBAL ◽  
F. BEREKSI-REGUIG
Keyword(s):  
Wavelet Transform ◽  
Heart Sound ◽  
Wavelet Packet ◽  
Extraction Methods ◽  
Heart Sounds ◽  
Discrete Wavelet ◽  
Clinical Tool ◽  
Prognostic Information ◽  
Transform Method ◽  
Time Frequency

This work investigates the study of heartbeat cardiac sounds through time–frequency analysis by using the wavelet transform method. Heart sounds can be utilized more efficiently by medical doctors when they are displayed visually rather through a conventional stethoscope. Heart sounds provide clinicians with valuable diagnostic and prognostic information. Although heart sound analysis by auscultation is convenient as a clinical tool, heart sound signals are so complex and nonstationary that they are very difficult to analyze in the time or frequency domain. We have studied the extraction of features from heart sounds in the time–frequency (TF) domain for the recognition of heart sounds through TF analysis. The application of wavelet transform (WT) for heart sounds is thus described. The performances of discrete wavelet transform (DWT) and wavelet packet transform (WP) are discussed in this paper. After these transformations, we can compare normal and abnormal heart sounds to verify the clinical usefulness of our extraction methods for the recognition of heart sounds.

scholarly journals Damage Detection on Sudden Stiffness Reduction Based on Discrete Wavelet Transform

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Bo Chen ◽  
Zhi-wei Chen ◽  
Gan-jun Wang ◽  
Wei-ping Xie
Keyword(s):  
Wavelet Transform ◽  
Damage Detection ◽  
Discrete Wavelet Transform ◽  
Sudden Change ◽  
Damage Index ◽  
Time Instant ◽  
Discrete Wavelet ◽  
Building Structures ◽  
Stiffness Reduction ◽  
Shear Building

The sudden stiffness reduction in a structure may cause the signal discontinuity in the acceleration responses close to the damage location at the damage time instant. To this end, the damage detection on sudden stiffness reduction of building structures has been actively investigated in this study. The signal discontinuity of the structural acceleration responses of an example building is extracted based on the discrete wavelet transform. It is proved that the variation of the first level detail coefficients of the wavelet transform at damage instant is linearly proportional to the magnitude of the stiffness reduction. A new damage index is proposed and implemented to detect the damage time instant, location, and severity of a structure due to a sudden change of structural stiffness. Numerical simulation using a five-story shear building under different types of excitation is carried out to assess the effectiveness and reliability of the proposed damage index for the building at different damage levels. The sensitivity of the damage index to the intensity and frequency range of measurement noise is also investigated. The made observations demonstrate that the proposed damage index can accurately identify the sudden damage events if the noise intensity is limited.

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