A compressively strained pseudomorphic Si1−xGex film being debonded from Si substrate by selective etching forms wrinkles with a uniform space periodicity. The present study provides experimental evidences and a theoretical model for the wrinkling process. To allow large deflection, non-linear Von Karman plate theory is employed. The amplitude and wavelength of wrinkles are determined by minimizing the total free energy of a debonded wrinkled film. The wrinkling analysis has shown that the amplitude and wavelength of wrinkled film are an outcome of a subtle compromise between bending energy, and normal and shearing components of the stretching energy. The wave number nondimentionalized over the depth of etch is a function of the membrane strain of a bonded film, Poisson's ratio, and the nondimensional film thickness.

Novel electrohydrodynamic (EHD) pump driven micro mixers are fabricated to study fluidic mixing in micro channels experimentally. Microscopic flow visualization experiments are presented to visualize microscale mixing in micro mixers. Mixing is achieved in a laminar flow by perturbing the main flow with EHD pumps in a micro channel. EHD pumps operate in a way to form cross-stream mixing mechanism by using either dc voltage or traveling wave signals. Experimental results show transverse or vortical cross-stream flows are generated within hundreds microns distance in the micro mixers, thereby increasing mixing.

To study the cutting forces, the carbide tip's surface temperature, and the mechanism of secondary chip and main chip formation of face milling stainless steel with a chamfered main cutting edge has been investigated. Theoretical values of cutting forces were calculated and compared to the experimental results with SUS 304 stainless steel plate as a workpiece material. Force data from these tests were used to estimate the empirical constants of the mechanical model and to verify its prediction capabilities. A comparison of the predicted and measured forces shows good agreement. A preliminary discussion is also made for the design of special tool holders and their geometrical configurations. Next, the tips mounted in the tool holders are ground to a chamfered width and the tool dimensions are measured by using a toolmaker microscope.

Recently, Shy and his co-workers developed a new turbulent flow system that used a pair of counter-rotating fans and perforated plates to generate stationary near-isotropic turbulence, as verified by LDV measurements, for the study of premixed turbulent combustion processes. This paper evaluates for the first time the correlations between spatial and temporal properties of small-scale intermittency in such a fan-stirred near-isotropic turbulence. These spatiotemporal properties are obtained simultaneously via high-speed digital particle image velocimetry together with wavelet analyses. It is found that the wavelet energy spectra in the inertial range of near-isotropic region all exhibit a slope of nearly −5/3 which spans at least from 3Hz to 100Hz. Characteristic scales, including the integral time and length scales, Taylor microscales, and viscous dissipation scales, are identified without the use of Taylor hypothesis. Thus, a direct evaluation of Taylor hypothesis in near-isotropic turbulence with zero mean velocity can be made. From variations of the flatness factor, equivalent to the 4th order velocity structure function, in the spatial and time domains, it is found that the characteristic spatial and temporal intermittent scales of intense vorticity structures in the dissipation range of the fan-stirred near-isotropic turbulence occur around 5 ∼ 8η and τk, respectively, where η and τk are the Kolmogorov length and time scales. These results are useful for further study of particle settling in turbulence, a problem of both engineering and geophysical interest.

This investigation presents the solution of kinematic wave equations for overland flow, in which the lateral term is determined from unsteady rainfall and the infiltration φ index model [1], in which the rate of abstractions is constant, yielding an excess rainfall hyetograph with a total depth that equals the depth of direct runoff over the watershed. Lateral inflow is inferred by the unit step function to represent an unsteady rainfall event; the solution uses the method of characteristics. Part of the discharge hydrograph that satisfies the boundary condition is semi-analytically solved, by a reduced, simple procedure, which does not require the use of numerical method such as finite difference. The analysis presented herein this investigation deals with both rising and falling stages. Example calculations, water surface profiles, and discharge hydrographs are also presented.

This research is focused on exploring the fluid loading effects on the dispersion curves of Lamb modes propagating in a piezoelectric plate. A theoretical treatment based on a partial wave analysis is developed to model the dispersion curves of Lamb modes propagating in an X-LiNbO3 plate loaded by a fluid with combined mechanical/dielectric properties. In particular, the mode-shifting characteristics caused by the fluid loading as a function of the propagation orientation are illustrated with numerical examples. Finally, for the case of water as an immersing fluid, individual attributions of the mechanical and dielectric loading effects causing the mode-shifting are analyzed. It is found that the dielectric loading effect dominates the mode-shifting while the mechanical density loading can be neglected while Lamb waves propagate in an X-LiNbO3 plate immersing in water. The current results provides useful information for the applications of acoustic plate mode (APM) devices used in liquid sensor applications.

Applying the concept of minimum potential energy and the variational method proposed in this paper, one can derive the governing equation and transversality conditions for the critical slip surface of a cohesive land slope described by simplified Janbu's model where both horizontal and vertical inter-slice forces are neglected. The governing equation, transversality conditions and boundary conditions were solved by the boundary integral equation method, which is a one dimensional BIEM, so that the critical slip surface and its associated minimal factor of safety can be determined effectively. By comparison of the results gotten from the boundary integral equation method and other numerical methods, it can be concluded, that, for some simplified cases, by using the boundary integral equation method on slope stability analysis of a cohesive land slope, a more reasonable result can be obtained.

An improved two-load method for whole-field complete determination of photoelastic parameters is presented. The dark-field isoclinic images are used to determine the isoclinic angles. Using two isoclinic maps obtained from two different loads effectively compensates the indeterminable points. The use of dark-field and light-field photoelastic images for normalization extends the two-load method to analyze dark-field photoelastic fringe patterns and avoids model movement. Larger errors on the determined fringe orders are further reduced by a least-squares quadric fitting. The results are compared well to the theoretical ones. Further comparison of the improved two-load method and the two-wavelength method are given.