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This paper aims to propose a new model to study the relationship between the acoustic properties of the thickness shear mode (TSM) in lateral field excited (LFE) film bulk acoustic wave resonator (FBAR) and the gap distance of the surface electrodes.

In the finite element analysis, harmonic and modal analyses are performed to obtain the admittance spectrum and determine the mechanical vibration mode. The results are used to modify the ideal model used in the theoretical calculation.

In the case of LFE FBAR, the acoustic velocity and electromechanical coupling coefficient (K2) of the TSM decreases as the gap distance decreases and there is a compromise between the exciting effectiveness and the acoustic properties.

The paper proposes a new method to study the dependences of the acoustic properties of the lateral field excited FBAR on the gap distances of the surface electrodes through the extraction of the static capacitance based on the finite element simulation results.

The purpose of this paper is to describe a parameter identification method based on multiobjective (MO) deterministic and non-deterministic optimization algorithms to compute the temperature distribution on transformer tank covers.

The strategy for implementing the parameter identification process consists of three main steps. The first step is to define the most appropriate objective function and the identification problem is solved for the chosen parameters using single-objective (SO) optimization algorithms. Then sensitivity to measurement error of the computational model is assessed and finally it is included as an additional objective function, making the identification problem a MO one.

Computations with identified/optimal parameters yield accurate results for a wide range of current values and different conductor arrangements. From the numerical solution of the temperature field, decisions on dimensions and materials can be taken to avoid overheating on transformer covers.

The accuracy of the model depends on its parameters, such as heat exchange coefficients and material properties, which are difficult to determine from formulae or from the literature. Thus the goal of the presented technique is to achieve the best possible agreement between measured and numerically calculated temperature values.

Differing from previous works found in the literature, sensitivity to measurement error is considered in the parameter identification technique as an additional objective function. Thus, solutions less sensitive to measurement errors at the expenses of a degradation in accuracy are identified by means of MO optimization algorithms.

The purpose of this paper is to investigate the use of hybrid‐excitation solutions, using contemporaneously permanent magnets and field coils, for DC machines intended to operate as the core of high‐reliability drives in critical applications supplied by batteries (e.g. fire‐extinguishing pumps, smoke blowers, etc.) where a roughly constant speed is required and a minimal use of electronic devices is prescribed to improve overall dependability.

A high‐reliability hybrid‐excitation DC motor, initially designed basing on theoretical considerations, is then analyzed using purposely developed 2D and 3D finite element method (FEM) electromagnetic models under static, dynamic, healthy, and faulty conditions.

The simulation results confirm that properly designed drives employing hybrid‐excitation DC motors may constitute an effective solution for applications requiring a very high reliability under DC supply with limited speed regulation capability.

The methodology employed exhibits the usual limits concerning the accuracy of FEM analysis: hysteresis is neglected, 2D simulations neglect axial component of fields, in 2D dynamic analysis the electrically discontinuous laminated cores are modeled as orthotropic continuous parts, commutator operation is approximated by means of a position‐dependent resistors network, and the excitation current provided by choppers is approximately considered as constant.

Hybrid excitation DC motors, which may be easily manufactured using existing facilities and mature technologies, might provide an interesting solution for emergency drives requiring minimal regulation capabilities and very high reliability under direct DC supply.

Hybrid excitation is not much investigated in the literature especially for DC motors, although such solution may result potentially interesting especially when a limited flux adjustment capability is required.

The purpose of this paper is to present a method for early crack detection in rotating shafts. A rotor-bearing system, consisting of an elastic rotor mounted on fluid film bearings, is used to detect the presence of the crack at a depth of around 5 percent of shaft radius. The fluid film bearings, the shaft and the crack introduce coupled bending vibrations both in the horizontal and vertical plane. Experimental time series of the rotor composite response under normal steady-state operation are uncoupled, to develop a signal processing procedure able to reveal the presence of the crack.

The variation of the coupling property that a crack (breathing or not) or a cut (always open) introduces into the system and the localization of the coupling in the time domain is a concept proposed as a means to detect transverse surface cracks in rotating shafts. This consideration is combined with the concept of external excitation for the development of an additional crack-sensitive response during system normal operation. Using an external excitation of an active magnetic bearing of specific duration, frequency and amplitude, the method uses this coupling variation during rotation.

The method is simple, quick and effective for early crack detection, being able to detect cracks as shallow as 5 percent of the shaft radius while the system is under normal operation, and can even be applied real-time. Experimental verification uses a simple elastic rotor with a cut mounted on fluid film bearings, with the cut producing similar coupling phenomena as an opened crack. Experimental results are encouraging.

The method used is simple, quick and effective for early crack detection, being able to detect cracks as shallow as 5 percent of the shaft radius while the system is under normal operation, and can even be applied real-time.

The paper aims to theoretically and experimentally investigate vibratory peg-bush alignment using elastic vibrations of the peg, when the peg is axially excited by a pressed piezoelectric vibrator on the upper end.

Experimental research of part alignment using elastic vibrations was performed and dependencies of alignment duration on excitation signal parameters and initial pressing force were defined for rectangular and circular cross-section parts. Mathematical model of two-mass dynamic systems with elastic contact model representing alignment process was created. Dependencies of system parameters on the alignment duration were obtained by numerically solving systems differential equations.

Theoretical and experimental investigation approved the usage of elastic vibrations for alignment of chamferless circular and rectangular cross-section parts. This novel method of part alignment compensates axial misalignment between mating parts by directional displacement of movably based bush.

Impact and non-impact interaction between bush and peg is possible; however, only non-impact regime was investigated. Static and dynamic coefficients of friction between the parts are equivalent and do not depend on relative velocity of parts.

The results are useful in designing reliable and effective assembly equipment with vibratory assistance alignment for peg-bush operations, which do not require auxiliary sensors and feedback systems. Use of a piezoelectric resonator for peg excitation makes this system easily adaptable to the existing automated assembly equipment.

The proposed method is a new approach to vibratory alignment. The data obtained during investigation expand the insight of the physical processes that drive bush to the axial alignment direction.

This paper aims to experimentally study the external flow characteristic of an isolated two-dimensional synthetic jet actuator undergoing diaphragm resonance.

The resonance frequency of the diaphragm (40 Hz) depends on the excitation mechanism in the actuator, whereas it is independent of cavity geometry, excitation waveform and excitation voltage. The velocity response of the synthetic jet is influenced by excitation voltage rather than excitation waveform. Thus, this investigation selected four different voltages (5, 10, 15 and 20 V) under the same sine waveform as experiment parameters.

The velocity field along the downstream direction is classified into five regions, which can be obtained by hot-wire measurement. The first region refers to an area in which flow moves from within the cavity to the exit of orifice through the oscillation of the diaphragm, but prior to the formation of the vortex of a synthetic jet. In this region, two characteristic frequencies exist at 20 and 40 Hz in the flow field. The second region refers to the area in which the vortices of a synthetic jet fully develop following their initial formation. In this region, the characteristic frequencies at 20 and 40 Hz still occur in the flow field. The third region refers to the area in which both fully developed vortices continue traveling downstream. It is difficult to obtain the characteristic frequency in this flow field, because the mean center velocities (ū) decay downstream and are proportional to (x/w)^−1/2 for the four excitation voltages. The fourth region reveals variations in both vortices as they merge into a single vortex. The mean center velocities (ū) are approximately proportional to (x/w)⁰ in this region for the four excitation voltages. A fifth region deals with variations in the vortex of a synthetic jet after both vortices merge into one, in which the mean center velocities (ū) are approximately proportional to (x/w)⁻¹ in this region for the four excitation voltages (x/w is the dimensionless streamwise distance).

Although the flow characteristics of synthetic jets had reported for flow control in some literatures, variations of flow structure for synthetic jets are still not studied under the excitation of diaphragm resonance. This paper showed some novel results that our velocity response results obtained by hot-wire measurement along the downstream direction compared with flow visualization resulted in the classification of five regions under the excitation of diaphragm resonance. In the future, it makes valuable contributions for experimental findings to provide researchers with further development of flow control.

The purpose of this paper is to analyze the liquid sloshing behaviors in two-dimensional tanks with various porous baffles under the external excitation.

Adopting the finite element method (FEM) and control variable method to study the impacts of the height, length, number, location, shape, porous-effect parameter of the porous baffle, the external load frequency and the shape of the tank on the liquid sloshing response.

The amplitude of the free surface can be reduced effectively when the baffle opening is appropriate. The anti-sway ability of the system increases in pace with the baffle’s height growing. Under the same conditions, the shapes of the baffles have an important effect on improving the anti-sway ability of the system.

As there exist the differences of the velocity potential between each side of the porous baffle, which means that there are two different velocity potentials at a point on the porous baffle, the conventional finite element modeling technologies are not suitable to be applied here. To deal with this problem, the points on the porous baffle are regarded as two nodes with the same coordinate to model and calculate.

A new model able to describe the high frequency (HF) behaviour of the laminated cores of AC machines is proposed. The aim is to compute the external flux density of machine cores, corresponding to electromagnetic emissions in the HF range when the skin effect is predominant.

For high frequencies, the skin depth is much lower than the thickness of a lamination and the external flux density is determined using a new analytical model. The validity of this model is confirmed by measurements performed on a magnetic core representing a small part of a large machine and a finite element 3D simulation.

For high frequencies, the external flux density is computed considering an equivalent current layer flowing on the laminated core external surface. Eddy currents in the laminated core have a large influence on the current density in this current layer.

The new model proposed is valid when the skin depth is lower than half the thickness of a lamination.

The knowledge of the machine magnetic core behaviour in the frame of the HF electromagnetic emissions has practical applications for large AC machine maintenance such as the localization of partial discharges in the winding insulation. With this model, it is possible to analyse the information given by small magnetic sensors placed between the machine core and the external frame to solve all the insulation problems.

The new proposed model is able to establish a link between the electric HF phenomena in the windings of a working machine and the magnetic flux density outside the laminated core.

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical fields. Looks at the coupling of fields in a device or a system as a prescribed effect. Points out that there are 12 contributions included ‐ covering magnetic levitation or induction heating, superconducting devices and possible effects to the human body due to electric impressed fields.

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.