Ultrasonic is a transport form of sound. There is no mass transportation, only energy transportation occurs in transfer process. Recently, the ultrasonic was widely used in a variety of purposes. For example¡Gsonar, non-destructive testing, washing and emulsification. Due to the effects of mechanical vibration of ultrasonic on the physiological can promote the percutaneous absorption, ultrasonic is widely used in medical cosmetic field. It can get amazing amount of spending and will continue growth every year. The skin is the body's largest organ, which can be divided into epidermis, dermis and hypodermis. There are two main approaches for drugs to be delivered through the skin: directly penetrate the epidermis and penetrate the lipid layer of cell space. The main purpose of this study is to executing numerical simulation through finite element analysis. By constructing the 3D FEM model of the skin, the effects of different level combinations of the three factors, massage time, amplitudes and frequencies of ultrasonic, on the equivalent strain distributions of the epidermis, dermis, hypodermis and muscle layers were studied, while the skin was massaged by using ultrasonic. The simulation results showed that the difference of maximum equivalent strain is nearly one hundred times between different factor¡¦s level combinations. That means the choice of the appropriate factor¡¦s level combination will affect the efficacy of ultrasonic massage seriously. The numerical simulation results also showed that amplitude is the most influential factor on the equivalent strain for every layers of skin except the epidermis.

In recent years multiferroic materials have great application potential in the ferroelectric random access memory and emerging spintronics development setting off the boom of the multiferroic materials research. It was assume that the ferroelectric and magnetic properties cannot coexist at the same temperature range or their coupling is weak making the searching for multiferroics in dream. Multiferroic materials have been discovered in recent years. Multiferroics may even be induced due to the strong coupling between artificial layers by growing multilayer technique. [1] [2] Among of which the BiFeO3 compound contains of antiferromagnetic and ferroelectric properties at room temperature. The BiFeO3 thin films manifests a larger spontaneous porlarization than that of the bulk and is highly capable of industrial application. In this study, Pb doped BFO (BPFO) this films were grown on top the conductive SrRuO3 layers. By varying BPFO¡¦s thickness, the strain effect the relative physical properties were studied. It is found that the lattice constants of SRO is totally different to that of STO substrate indicating strain relaxation. Similar phenomena are also discovered for BPFO thin film which is believed due to the tilting effect on the SRO/STO interface.

It has been proven by J.C.Criscione that constitutive relations(mixed approach) based on a set of five strain invariants (Beta-1, Beta-2, Beta-3, Beta-4, Beta-5) are useful and stable for experimentally determining response terms for transversely isotropic material. On the other hand, Rivlin’s classical model is an unsuitable choice for determining response terms due to the co-alignment of the five invariants (I1, I2, I3, I4, I5). Despite this, however, a mixed (Lagrangian and Eulerian) approach causes unnecessary computational time and requires intricate calculation in the constitutive relation. Through changing the way to approach the derivation of a constitutive relation, we have verified that using an Eulerian approach causes shorter computational time and simpler calculation than using a mixed approach does. We applied this approach to a boundary value problem under specific deformation, i.e. finite extension and torsion to a fiber reinforced circular cylinder. The results under this deformation show that the computational time by Eulerian is less than half of the time by mixed. The main reason for the difference is that we have to determine two unit vectors on the cross fiber direction from the right Cauchy Green deformation tensor at every radius of the cylinder when we use a mixed approach. On the contrary, we directly use the left Cauchy Green deformation tensor in the constitutive relation by the Eulerian approach without defining the two cross fiber vectors. Moreover, the computational time by the Eulerian approach is not influenced by the degree of deformation even in the case of computational time by the Eulerian approach, possibly becoming the same as the computational time by the mixed approach. This is from the theoretical thought that the mixed approach is almost the same as the Eulerian approach under small deformation. This new constitutive relation by Eulerian approach will have more advantages with regard to saving computational time as the deformation gets more complicated. Therefore, since the Eulerain approach effectively shortens computational time, this may enhance the computational tools required to approach the problems with greater degrees of anisotropy and viscoelasticity.

Health monitoring is an important field as small failures can build up and cause a catastrophic failure. Monitoring the health of a structure can be done by measuring the motion of the structure through the use of strain sensors. The limitations of current strain sensing technology; cost, size, form could be improved. This research intends to improve current strain sensing technology by creating a conductive polymer composite that can be used monitor health in structures. Conductive polymer composites are a viable candidate due to the low costs of manufacturing, tailorable mechanical and electrical properties, and uniform microstructure. This work will focus on determining if a all-polymer composite can be used as a strain sensor, and investigating the effects of filler, doping and latex effect the electrical and strain sensing properties. Strain sensors were prepared from polyaniline (PANI)-latex composites, the morphology, mechanical, electrical and strain sensing properties were evaluated. These strain sensors were capable of repeatable measuring strain to 1% and able to measure strain until the substrates failure at 5% strain, with a sensitivity (measured by gauge factor) of between 6-8 (metal foil strain sensors have a gauge factor of 2). The best performing strain sensor consisted of 4 wt.% polyaniline. This composition had the best combination of gauge factor, linearity, and signal stability. Further experiments were conducting to see if improvements could be made by changing the polymer used for the matrix material, the molecular weight and the level of doping of the polyaniline. Results indicate through differences in strain sensing response; lower hysteresis and unrecoverable conductivity, that polyaniline latex composites can be adjusted to further improve their performance. The polyaniline-latex composites were able to repeatable measure strain to 1%, as well as strain until failure and with gauge factor between 6-8, and a 70% increase in signal at failure. These properties make these composites viable candidates to monitor health in structures, buildings, bridges, and damns.

This research shows an experimental set-up of measuring forces acting on single cylinder in cross flow provided by a water tunnel. Water was also released at various directions from the cylinder surface to study the effect of momentum injection on cylinder forces. The fluid forces on the cylinder was measured by a strain gauge bonded on long-thin plat which is connected to the cylinder. The drag and lift coefficients of the cylinder were measured with momentum injection of various direction and magnitude. Experimental results show that the drag coefficient is effectively reduced with momentum injection at streamwise direction. Negative drag coefficient (propulsion) can be obtained if the magnitude of momentum inject is large enough. When the momentum injection has cross-stream component, lift force is obtained with its value depending on the magnitude of momentum injection. For higher Reynolds number, the magnitude of momentum injection has to be increased to maintain the effectiveness of momentum injection.

Semiconductor technology has already got into nanometer scale. As the dimension keeping scaling down, we can get more transistor in the same area, and furthermore the frequency and performance are also enhanced. But nowadays the development of the lithography technology has come to the neck; we must find another way to improve the performance of transistor. In this study, we fully discuss the electrical characteristics and the hot carrier effect as the channel of the N-MOSFETs being strained. In order to strain the channel, silicon substrate is bent by applying external mechanical stress, the lattice of channel will be strained after applying uniaxial tensile stress. Therefore, we successfully improve drain current and carrier mobility of NMOS, and the increasing rates are 22% and 30% respectively. In addition, we can understand the influence of hot carrier effect on strain silicon by bending silicon substrate with external mechanical stress. With the increase of curvature, substrate current goes up. We offer an explanation to verify this result.

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There are two aspects in this study: cylinder penetrations and XBP (Expendable Bottom Penetrometer) interpretations. The cylinder studies firstly investigate the relationship between the soil resisting force and penetration depth by a series of rateindependent finite element analyses of pre-embedded penetration depths, and validate the results by upper and lower bound solutions from classical plasticity theory. Furthermore, strain rate effects are modeled by finite element simulations within a framework of rate-dependent plasticity. With all forces acting on the cylinder estimated, penetration depths are predicted from simple equations of motion for a single particle. Comparisons to experimental results show reasonable agreement between model predictions and measurements. The XBP studies follow the same methodology in investigating the soil shearing resistance as a function of penetration depth and velocity by finite element analyses. With the measurements of time decelerations during penetration of the XBP, sediment shear strength profile is inferred from a single particle kinetic model. The predictions compare favorably with experimental measurements by vane shear tests.

The strain effect on La0.67Ca0.33MnO3 and La0.8Ba0.2MnO3 thin films on SrTiO3 (001) substrate with different thicknesses has been studied by X-ray absorption near edge spectroscopy (XANES), which can reveal the details of the coupling between cations and anions. The strain may suppress the TC of LCMO films while enhancing that of LBMO films. The theoretical calculation results suggest the unoccupied states of the third structure of XANES are formed by much more complex hybridization of O 2p to Mn 4sp, La 6s and (Ca 4sp or Ba 6sp) orbitals. The change of the absorption intensity of the second and third structures is compatible to the TC change of both films due to the strain effect. This strongly suggests that the strain effect on LCMO and LBMO thin films is mainly associated with the bonding situation between O and La(Ca or Ba) ions.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.