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The phase-modulation (PM) noise performance of an assortment of oscillatory and nonoscillatory microwave components under vibration at 10 GHz is studied. The effect of vibration on the amplitude-modulation (AM) noise is analyzed.

The thickness-shear vibration of an AT-cut quartz plate with elliptical electrodes is analyzed, where the electrodes are optimal in the sense of Mindlin in that they have satisfied the criterion for Bechmann's number in every direction. The results have shown that optimal crystal blank geometry is elliptical and have suggested a way of machining elliptical crystal blanks.

The ultrasonic trapping of small particles by a vibrating rod is studied. The effects of operating frequency, rod radius, particle radius and other physical parameters are examined and useful guidelines are provided for optimizing the trapping capability.

The suitable condition of an onload tap changer (OLTC) is essential for the operation of a power transformer. It is extremely desirable to have some indicators to assess the OLTC condition, especially if these indicators are capable of being used in an online monitoring system that does not affect the normal operation of the transformer. This paper describes a methodology by using envelope analysis based on the Hilbert transform and orthogonal decomposition of the wavelet to determine the main diagnostic parameters for power transformer OLTC condition assessment by means of vibration measurements during the tap changer operation. Index Terms--Hilbert transform vibration analysis, onload tap changer (OLTC), wavelet transform.

The article talks about a recently developed technique called the double synchronized switch harvesting (DSSH), which is used for the harvesting of optimized energy using piezoelectric microgenerators. The approach is shown to be extremely beneficial, as it allows a fine trade-off between the vibration damping and energy harvesting.

This paper relates to a vibration analysis of brush-less dc (BLDC) motors using the asymmetrical Z-axis overhang of permanent magnet (PM). In BLDC motor, the asymmetrical Z-axis overhang of PM generates Z-axis thrust, which leads to Z-axis eccentric force by commutated current on the rated load and then the Z-axis vibration. The Z-axis thrust ripple, which is the source of Z-axis vibration under commutated current, is analyzed by using 3-D finite element method, and the phenomena of Z-axis vibration are analyzed by experimentation. Index Terms--Permanent-magnet (PM) overhang, vibration, Z-axis thrust, 3-D finite-element method (3-D FEM).

In this paper, we present new strategies of vibration suppression in flexible shaft of a motor with active and passive magnetic forces. Shaft magnetic damping originates from the principle of a bearingless motor having a radial magnetic force generation. Radial force is used for shaft vibration suppression to go through the first critical speed. Simplifications are described in a suppression force system. We propose the elimination of a power source with self-excitation, as well as the elimination of sensors, controllers, and inverters, although the effectiveness is limited. Index Terms--Bearingless motor, flexible shaft, induction motor, vibration suppression.

The paper describes a numerical investigation of the problem of flow-induced, off-track vibration of the slider in a disk drive. The flow field was simulated in a 3.5-in, 10 000 rpm disk drive using FLUENT flow-modeling software, which yielded the aerodynamic forces and moments for various components of the head stack assembly (HSA). The finite-element model of the HSA was developed using ANSYS software. Then off-track vibration of the slider caused by the aerodynamic loads of different HSA components was computed. The computations showed that the arm experiences the largest fluctuations of aerodynamic load. However, the loadbeam base region appears to make the largest contribution to off-track vibration of the slider, due to the vortex shedding generated by the side tabs of the loadbeam base region. Index Terms--Computational fluid dynamics (CFD), flow-induced vibration, hard disk drive, head stack assembly, slider.

The design of a magnetically levitated superconducting conveyer for wafer transportation is discussed. Findings reveal that the usage of proportional and differential control suppresses the vibrations of displacement.

A Lyapunov approach to the characterization of forced vibration for continuous-time systems was recently proposed in [12]. The objective of this paper is to derive counterpart results for discrete-time systems. The class of oscillatory input signals to be considered include sinusoidal signals, multitone signals, and periodic signals which can be described as the output of an autonomous system. The Lyapunov approach is developed for linear systems, homogeneous systems (difference inclusions), and nonlinear systems (difference inclusions), respectively. It is established that the steady-state gain can be arbitrarily closely characterized with Lyapunov functions if the output response converges exponentially to the steady state. We also evaluate other output measures such as the peak of the transient response and the convergence rate. Applying the results to linear difference inclusions, optimization problems with linear matrix inequality constraints can be formulated for the purpose of estimating the output measures. This paper's results can be readily applied to the evaluation of frequency responses of general nonlinear and uncertain systems by restricting the inputs to sinusoidal signals. Similar to continuous-time systems, it is observed that the peak of the frequency response can be strictly larger than the [L.sup.2] gain for a linear difference inclusion. Index Terms--Difference inclusions, forced vibration, Lyapunov functions, steady-state gain.

A novel radio frequency integrated circuit RFIC)-compatible process is described for concave-suspended high-Q solenoid inductors. The shock testing results have shown that the suspended inductor is almost free of influence from environmental vibration and shock.

Adjustable balancers are useful in applications where rotational imbalance is frequently varied. For example, in media level servo track writers used in the hard disk drive industry, a set of blank disks is loaded on a spindle motor for the purpose of servo writing. Since servo writing is performed at high speeds, imbalance introduced by disks and spacers results in significant vibrations that can affect the quality of the servo writing process. This paper proposes a new configuration of adjustable balancer that enables to compensate for rotational imbalance each time a new set of blank disks is loaded into the servo track writing machine. The adjustable balancer is ring shaped with a number of grooves displaced around axis of rotation. Steel balls are placed inside the grooves and held by permanent magnets. Imbalance compensation is achieved by electromagnetically activated release of the steel balls. The main advantage of the proposed configuration is its large compensation range. Presented three-dimensional finite-element analysis results and experimental results demonstrate and prove the effectiveness of this novel configuration. Index Terms--Electromagnetic forces, hard disks, vibrations.

Switched reluctance machines (SRM) offer attractive attributes for automotive applications. These include robustness to harsh operational conditions, rugged structure, fault resilient performance, and a wide range of speed. The main debate over the adequacy of switched reluctance drives in automotive applications has often focused on efficiency and position sensorless control over the entire speed range, adaptation of control algorithms in the presence of parameter variations, and high levels of acoustic noise and vibration. The present paper demonstrates three key technologies developed over the past few years that have resulted in tangible improvements in the performance of SRM/generators (SRM/G) as related to the above areas of interest. This paper intends to illustrate the new possibilities and remaining challenges in applications of SRM in automotive industry. The proposed technologies have been validated by simulation and experimental results. Index Terms--Acoustic noice, switched reluctance machines (SRM), vibration.

Electrically and mechanically excited resonance in micromachined circular piezoelectric diaphragms is investigated. The diphagram structures are piezoelectric unimorphs consisting of Pb(Zr0.52, Ti0.48)O3(PZT) films and thermally grown silicon oxide (SiO2) layers.

As mechanical vibration usually exists in HV motors and generators, its influence on the partial discharge (PD) needs to be studied so as to improve the reliability of on-line PD monitoring method, in this report, the mechanical vibration frequency was synchronized to the power frequency and the effects of vibration phase and frequency were investigated. Because the length of the discharge gap changed with the vibration, obvious variation in the slot-PD patterns was observed at different vibration lead phase and frequency. Moreover, when the vibration amplitude was large, it was also found that the PD behavior at low voltage just above the PD inception voltage was different from that at higher voltage. This was explained in terms of the effects of the field variation in the gap due to the vibration and the charges left on the insulating surface due to PD. Index Terms partial discharges, vibration, generator, coil

Past research on vibration energy harvesting has focused primarily on the use of magnets or piezoelectric materials as the basis of energy transduction, with few experimental studies implementing variable-capacitance-based scavenging. In contrast, this paper presents the design and demonstration of a variable-capacitance vibration energy harvester that combines an asynchronous diode-based charge pump with an inductive energy flyback circuit to deliver 1.8 [micro]W to a resistive load. A cantilever beam variable capacitor with a 650-pF dc capacitance and a 348-pF zero-to-peak ac capacitance, formed by a 43.56 [cm.sup.2] spring steel top plate attached to an aluminum base, drives the charge pump at its out-of-plane resonant frequency of 1.56 kHz. The entire harvester requires only one gated MOSFET for energy flyback control, greatly simplifying the clocking scheme and avoiding synchronization issues. Furthermore, the system exhibits a startup voltage requirement below 89 mV, indicating that it can potentially be turned on using just a piezoelectric film. Index Terms--Variable-capacitance-based energy conversion, vibration energy harvesting, vibration energy scavenging.

An electroelastic laminated plate theory is adopted to analyze the vibration behaviors of the composite piezoelectric/elastic trimorph ring transducer under mechanical traction-free and electric constant-voltage boundary conditions. The analysis includes resonance and antiresonance frequencies, electric current response, dynamic and energy maximized electromechanical coupling coefficients.

A study is made for energy trapping, a behavior of thickness-shear modes crucial to applications and revealed that two-dimensional equations for asymmetrically electrode piezoelectric are obtained, and the electrodes present constraints on plate electric potentials of various orders. The equations obtained and the results of thickness-shear modes are useful for the analysis and design of piezoelectric devices but not suitable for studying electrode mismatch.

High frequency vibrations of piezoelectric crystal plates exhibit a strong coupling of the thickness-shear mode, which is the primary working and the flexural mode and is considered spurious, as the pure thickness-shear always is preferred in a typical resonator. To achieve this, the length of a crystal blank should be carefully chosen such that coupling is at its weakest, usually amidst the two strong coupling points.

The vibration characteristics of an asymmetric, three-layered piezoceramic circular bimorph under traction-free boundary conditions, by applying the electroelasticity and Kirchhoff plate theory are investigated. The theoretical and experimental results show that only the resonant frequencies of radial extensional vibrations can be measured by impedance analysis.

Vibration characteristics of thin piezoceramic annular disks with stress-free boundary conditions are examined by theoretical analysis, numerical simulation and experimental measurement. The dynamic electromechanical coupling coefficient of K(sub d) of all modes for extensional vibrations would approach limit values as alpha ---> 1 and K(sub d) of the second mode increases when alpha increases and is greater than that of the first mode for alpha greater than 0.287.

The equivalent constant method is used to investigate the transverse vibration of piezoceramic disks and annuli. By the cubic function lambda(super 2) (nu) and transverse frequencies, which are obtained by experiment, the Poisson's ratio nu(sub p) and planar electromechanical coupling coefficient k(sub p) can be determined by transverse modes and can be applied to the isotropic material.