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The paper discusses the common physical origin of heat conductance and heat radiation, proposes a simple model of micro and nanoscale heat transport caused by Casimir/van der Waals intermolecular forces, and addresses some difficulties arising in common applications of the conventional theory of heat radiation to micro and nano scale systems. [ABSTRACT FROM AUTHOR]

Studies the effect of morphology on flying height modulation (FHM) of a sub-10-nm flying air bearing slider by experiment and simulation. Different frequency bandwidths used in the analysis; Frequency content of the disk morphologies; Comparison between the FHM from experiment and simulation for disk C.

Abstract: The dynamics of a commercially available hard disk drive were investigated using both experimental and numerical techniques. The drive has a storage capacity of 1 GB with two 3 1/2-inch disks. First, each individual component--disk, suspension assembly, actuator arm, and arm coupled with the assembly--was briefly studied. Then, modal experiments were performed on the drive in both states of the disks, stationary or rotating. A finite element (FE) model for studying the dynamics of the drive was created. The model consists of one disk, two actuator arms, and two suspension assemblies. Good correlation between the experiment and FE analysis was achieved. It was shown that the drive exhibits very complicated modal properties and that the actuator arm significantly affects the dynamics of the drive, especially as regards track following of the sliders. [ABSTRACT FROM AUTHOR]

A laser-Doppler vibrometer was used to detect gated harmonic surface waves traveling along a steel block, together with their reflections from a rectangular plate attached to the block through a viscous couplant. A signal demodulator was designed to allow visualization of the waves on an oscilloscope, and computer data acquisition was performed. Using various plates and couplants, curves showing the reflected/incident power ratio as a function of the wavelength were obtained and compared with those obtained from a previous theoretical analysis. The correlation between the positions, number, and amplitudes of the resonances obtained from experiment and theory was analyzed, as was the influence of the couplant. [ABSTRACT FROM AUTHOR]

We study the recently derived reflection coefficient for plane waves in a liquid that are incident on the liquid-solid interface of a solid half-space, which consists of a single layer of one elastic material bonded to a substrate of a different material. Plots of the magnitude of the reflection coefficient versus the incident angle are presented for many sets of material parameters and values of frequency f and layer thickness d. The use of the results presented for the study of nonspecular reflection of bounded acoustic beams is of primary interest. We therefore seek to identify all the critical incidence angles for nonspecular reflection. We find that nonspecular reflection can occur, not only in connection with surface waves that are purely propagating modes in the absence of the liquid, but also for leaky modes on a layered half-space, provided the leakage is not too great. We also investigate, in particular, the surface wave propagation for the case of a stiff layer on a soft half-space, and we find that the purely propagating mode cuts off with increasing fd when its speed reaches the shear wave speed of the substrate, as reported in the literature. However, as fd increases further, a leaky mode appears that approaches the Rayleigh wave for the layer. This leaky mode is also associated with nonspecular reflection for large enough fd. [ABSTRACT FROM AUTHOR]

An experimental investigation was conducted to determine the effects of different edge conditions and face mount backing conditions on the electrical response of strongly coupled piezoelectric disks with electroded faces on which spatially nonuniform forces are applied by a pencil lead breaking mechanism. Various mounting schemes were employed to simulate traction-free, simply supported, and fixed edge conditions. The response was found to be relatively insensitive to changes in the edge conditions. Experiments were also conducted on a commercially available transducer in various stages of dismantlement. It was revealed that the main structural element for controlling the electrical output was the impedance matched backing that is epoxied to the inner face of the crystal. It was concluded that mathematical models for characterizing transducers subject to nonuniform face loadings can incorporate the analytically most convenient edge conditions but must also include a suitable model for the backing. [ABSTRACT FROM AUTHOR]

An approximate two-dimensional theory is used to study the electromechanical behavior of face electroded, circular, piezoelectric (PZT) disks of the type used in transducers. Solutions are obtained for the voltage generated in both free and forced motions due to nonaxisymmetric initial conditions and loading. Both free and simply supported edge conditions are also considered. Specific numerical results are obtained for certain cases and these results are compared with corresponding experimental observations. It is found that in the presence of electroded faces and insulated edges the general nonaxisymmetric problem reduces to an equivalent axisymmetric one involving only the extensional motions as far as the voltage difference between the electrodes is concerned. It is further observed that the output voltage time history is dominated by contributions due to radial modes of motion in the edge free case, but that only the thickness modes of motion contribute to this voltage in the simply supported case. This observation is relevant to transducer design since the analysis and results are vastly simpler in the latter case. [ABSTRACT FROM AUTHOR]

A recently derived approximate two-dimensional theory is used to predict the transient output voltage generated in circular PZT disks after sudden release from a static deformation caused by axisymmetric loads applied to the faces. Three specific loading cases are considered (a) a concentrated central normal force on one face with an opposing peripheral ring load on the other, (b) opposing uniform normal pressure, and (c) opposing central normal forces. The theoretical power spectra and time histories are compared with experimental observations for the same loading cases, and they are found to be in good overall agreement. It is found in all loading cases considered that the output voltage is produced by the lowest longitudinal thickness mode of motion together with the first few (up to 12) longitudinal radial modes. The thickness mode contribution decays out after 5-15 μs so that the remainder of the signal is produced by radial modes. The results presented here should contribute to a better understanding of electromechanical transducers made with piezoelectric plates. [ABSTRACT FROM AUTHOR]

Nanoindentation experiments and in situ monitoring of acoustic emission (AE) were used to investigate the evolution of deformation in polycrystalline silicon-carbide thin films. An acoustic sensor attached to the holder of the indenter tip was used to continuously record the AE signal during nanoindentation. The amplitudes of the AE wave forms were used to analyze the response of the indented films in the time domain. In addition, a hybrid time-frequency analysis of the AE events was performed in order to determine the dominant frequencies of the deformation events encountered during nanoindentation. The effects of the film thickness and microstructure and the indenter tip radius on the film deformation behavior are interpreted in terms of the AE response and associated deformation mechanisms. The findings of this study demonstrate that in situ AE monitoring provides potentially useful information about microstructure changes associated with nanoscale deformation processes, such as grain boundary cracking, in thin films subjected to normal contact loading. [ABSTRACT FROM AUTHOR]