نتایج جستجو برای: vibration mode
تعداد نتایج: 269836 فیلتر نتایج به سال:
quantification of arterial elasticity and its dependency to age is considered in this paper. we use radiofrequency (rf) signals fromcarotid artery ultasonography to evaluate this dependency. blood pressure, blood flow, and tethering to surrounding tissue are the maincauses of the motion of the carotid wall. tracking carotid artery wall motion from a series of ultrasound b‑mode images is challen...
This paper presents a new control structure to reduce torque ripple in switched reluctance motor. Although SRM possesses many advantages in motor structure, it suers from large torque ripple that causes some problems such as vibration and acoustic noise. In this paper another control loop is added and torque ripple is de ned as an objective function. By using fuzzy sliding mode strategy, the DC...
This article presents the design and analysis of a novel dynamic stiffness tuning vibration absorber working with Magnetorheological elastomers (MRE). In this design, the MRE worked in a shear mode, but its MR effect was significantly enhanced by dynamically squeezing the sample thickness with an embedded piezoelectric (PZT) actuator. With this design, both the quasi-static magnetic field and t...
The new generation of condition monitoring and diagnostics systems differs by the detailed solution of diagnostic problems that allows making a step from machine vibration state monitoring to the monitoring of the machine technical condition. Most rotating machine defects can be detected by such a system much before dangerous situations occur. It allows the efficient use of stationary on-line c...
The detection of the vibration signal from human vocal folds provides essential information for studying human phonation and diagnosing voice disorders. Doppler radar technology has enabled the noncontact measurement of the human-vocal-fold vibration. However, existing systems must be placed in close proximity to the human throat and detailed information may be lost because of the low operating...
This study proposes a fault detection and diagnosis method for bearing systems using ensemble empirical mode decomposition (EEMD) based feature extraction, in conjunction with particle swarm optimization (PSO), principal component analysis (PCA), and Isomap. First, a mathematical model is assumed to generate vibration signals from damaged bearing components, such as the inner-race, outer-race, ...
Periodic composite ultrasonic transducers offer many advantages but the periodic pillar architecture can give rise to unwanted modes of vibration which interfere with the piston like motion of the fundamental thickness mode. In this paper, viscoelastic loss is incorporated into a three-dimensional plane wave expansion model (PWE) of these transducers. A comparison with experimental and finite e...
A continuing trend these days is the use of micro-electro-mechanical actuators with electronic circuitry to fabricate MEMS devices such as micro-switches, hard disks, optical micro-mirrors ... One of the problems with the electrostatic MEMS actuator is that when an electrical voltage is applied to these devices, the micro-actuators undergo a residual vibration before reaching their permanent po...
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