Advancements in technologies such as microelectromechanical systems (MEMS), display devices, biomedical products have created an increasing requirement for miniature components on the scale of micrometers to nanometers. Currently, a commonly used fabrication for miniaturization is LIGA (Lithographie, Galvanoformung, and Abformung). It is a reliably manufacturing method for high-aspect-ratio microstructures with a precision of less than one micrometer. The use of electroplating within LIGA techniques, however, limits the range of materials that can be used. But the main disadvantage of LIGA is its cost: high-energy X-rays generated by synchrotron equipment. The homogeneous and isotropic characteristics of amorphous bulk metallic glasses (BMGs) due to the absence of crystallites, grain boundaries and dislocations lead to the scale of the metallic-glass structures can be miniaturized down to the atomic scale, which presents very high strength, hardness, elastic strain limit and corrosion resistance. In addition, the excellent workability and surface printability in the supercooled liquid state (the region defined from the glass transition temperature (Tg) to the crystallization temperature (Tx) of BMG) has been considered to be one of the most attractive properties of BMGs. The lighter Mg-based metallic glasses exhibit their superior glass forming ability (GFA). Consequently, the using of Mg-based BMGs can gain the goals of light devices and simplify manufacturing process. In this study, therefore, besides the study of LIGA process, a new process utilize the thermoplastic properties of BMGs is presented. First, UV (ultraviolet) -LIGA, a more economical process than LIGA, is used to fabricate the master mold with nickle-cobalt (Ni-Co) alloy. Then, this mold is applied to hot emboss on Mg58Cu31Y11 amorphous alloy to form a secondary mold. The hot embossing temperature is set at 423 K (150 oC) according to the Tg of the BMG around 413 K (140 oC). This embossing process shows that the thermoplastic forming ability of the BMG material is better than Polymethylmethacrylate (PMMA) which requires high hot embossing pressure. BMG is not only a good material for hot embossing process to fabricate microstructure directly, but also a fast-forming material for mold (or die) fabrication. On the other hand, other replicated-able moulds are presented to demonstrate the multifunctional ability of BMGs. First, a mold of oxygen free copper (OFC) with a very low hardness of 1.606 GPa, which is a popular material for machining due to its good machinability, is used to hot emboss on Mg58Cu31Y11 BMG with a higher hardness of 3.445 GPa. Second, micro triangular-pyramidal array (MTPA) on a tungsten (W) steel mold is transferred on Mg58Cu31Y11 BMG using this modified multi-step hot-embossing method to reduce the pattern size. In addition, scratch test with the Nano Indenter® XP system is used to study the mechanical behavior of the Mg58Cu31Y11 BMG for the application such as surface printability.

Bulk food exist in various kind of food, can be purchased by individual needs and quantities required, customer in Taiwan still stick to bulk food and the way sales. Recent year, many problems have revealed the bulk food safety issue. Therefore, Department of Health enacted bulk food labeling regulation in 2009 to clarify what information to be revealed, and has advocating the information to consumer about how to choose bulk food. The government hopes to increase the consumer knowledge and avoid food hazard. We can tell that knowledge must be an important part in decision procedure of food purchasing, but a few of research concern this issue. Hence, in this research product knowledge and other variables are discussed and selected to form research model. This research also discovered the bulk food safety situation unprecedentedly, gives an overview to readers. The goals of this research are find the mediator effect within involvement, perceived quality and repurchase intention and the moderator effect of product knowledge between the relationships of perceived quality and repurchase intention. Samples of 973 collected through questionnaire survey, tested the hypotheses by regression analysis. The result showed the three variables did have partial mediator effect. And the moderator effect was confirmed, product knowledge will weakened the relationship, implied the bulk food safety information advocacy would help to change the customer decision. Based on the result, suggestions are as followed: government should keep on educating consumer to establish proper food decision criteria; bulk food producer and distributor should improve the information reveal and food quality control spontaneously, to win customers¡¦ perceived quality and increase purchase.

Wave attenuation by vegetation is a highly dynamic process and its quantification is important for accurately understanding and predicting coastal hydrodynamics. However, the influence of vegetation on wave dissipation is not yet fully established nor implemented in current hydrodynamic models. A series of laboratory experiments were conducted at the Haynes Coastal Engineering Laboratory and in a two-dimensional flume at Texas A and M University to investigate the influence of relative vegetation height, stem density, and stem spacing uniformity on wave attenuation. Vegetation fields were represented as random cylinder arrays where the stem density and spatial variation were based on collected field specimens. Experimental results indicate wave attenuation is dependent on relative vegetation height, stem density, and stem spacing standard deviation. As stems occupy more of the water column, an increase in attenuation occurred given that the highest wave particle velocities are being impeded. Sparse vegetation fields dissipated less wave energy than the intermediate density; however, the extremely dense fields dissipated very little, if any, wave energy and sometimes wave growth was observed. This is possibly due to the highest density exceeding some threshold where maximum wave attenuation capabilities are exceeded and lowering of damping ensues. Additionally, wave attenuation increased with higher stem spatial variation due to less wake sheltering. A one-dimensional model with an analytical vegetation dissipation term was developed and calibrated to these experimental results to capture the wave transformation over the vegetation beds and to investigate the behavior of the vegetation field bulk drag coefficient. The best fit between predicted and measured wave heights was obtained using the least squares method considering the bulk drag coefficient as the single calibration parameter. The model was able to realistically capture the wave transformations over vegetation. Upon inspection, the bulk drag coefficient shared many of the dependencies of the total wave dissipation. The bulk drag coefficient increased with larger relative vegetation heights as well as with higher stem spacing standard deviation. Higher densities resulted in a lowering of the bulk drag coefficient but generally an increase in wave attenuation. These parameters and their influences help in identifying the important parameters for numerical studies to further our understanding of wave attenuation by wetlands.

Crown fires, the fastest spreading of all forest fires, can occur in any forest type throughout the United States and the world. The occurrence of crown fires has become increasingly frequent and severe in recent years. The overall aim of this study is to estimate the forest canopy fuel parameters including crown base height (CBH) and crown bulk density (CBD), and to investigate the potential of using airborne lidar data in east Texas. The specific objectives are to: (1) propose allometric estimators of CBD and CBH and compare the results of using those estimators to those produced by the CrownMass/FMAPlus software at tree and stand levels for 50 loblolly pine plots in eastern Texas, (2) develop a methodology for using airborne light detection and ranging (lidar) to estimate CBD and CBH canopy fuel parameters and to simulate fire behavior using estimated forest canopy parameters as FARSITE inputs, and (3) investigate the use of spaceborne ICEsat /GLAS (Ice, Cloud, and Land Elevation Satellite/Geoscience Laser Altimeter System) lidar for estimating canopy fuel parameters. According to our results from the first study, the calculated average CBD values, across all 50 plots, were 0.18 kg/m³ and 0.07 kg/m³, respectively, for the allometric equation proposed herein and the CrownMass program. Lorey’s mean height approach was used in this study to calculate CBH at plot level. The average height values of CBH obtained from Lorey’s height approach was 10.6 m and from the CrownMass program was 9.1 m. The results obtained for the two methods are relatively close to each other; with the estimate of CBH being 1.16 times larger than the CrownMass value. According to the results from the second study, the CBD and CBH were successfully predicted using airborne lidar data with R² values of 0.748 and 0.976, respectively. The third study demonstrated that canopy fuel parameters can be successfully estimated using GLAS waveform data; an R² value of 0.84 was obtained. With these approaches, we are providing practical methods for quantifying these parameters and making them directly available to fire managers. The accuracy of these parameters is very important for realistic predictions of wildfire initiation and growth.

In this study, AlN films are deposited using reactive RF magnetron sputter on various bottom metals, such as Mo, Al and Pt. The orientation of piezoelectric AlN thin films on different bottom electrode materials are investigated. Moreover, the acoustic Bragg reflectors deposited by DC magnetron sputter are composed of alternating layers of high and low acoustic impedance materials. To improve the performance of the reflectors, rapid thermal anneal and deposition process control over roughness of the thin film are also investigated. The resonance characteristics are improved obviously by deposition process control over thin films. The roughness control is the key factor of good frequency responses of SMR. In addition, the more layer of the reflectors the better the frequency response we obtained. The frequency responses of SMR are slightly improved by rapid thermal annealing procsess. Although defects in the thin films would be eliminated, nevertheless the thin film roughness became worse after annealing. This phenomenon would limit the improvement of frequency responses.

Recently, there are great demands for RF band pass filters with smaller size/volume, lighter weight, and higher performance for advanced mobile/wireless communication system. However, fabricated RF filters using traditional lumped element, dielectric resonators, or surface acoustic wave¡]SAW¡^filters have difficulties in on-chip integration, power handling capability, and temperature compensation. Alternatively, thin-film bulk acoustic wave resonator¡]FBAR¡^filters are very suitable devices for MMIC¡¦s since they can be fabricated on Si or GaAs substrates at a lower magnitude than lumped elements or dielectric resonators, plus they have a much lower insertion loss and higher power handling capabilities than surface acoustic wave devices and full integration with other CMOS RF IC circuitry for realizing a goal of system on chip¡]SOC¡^. In their simplest form, practical FBARs consist of a sputtered piezoelectric thin film sandwiched between top and bottom electrodes onto which an electric field is then applied. An FBAR must have two acoustically reflecting surfaces in order to trap energy and produce resonating characteristics. For this purpose, the thin film bulk acoustic resonator has to be isolated acoustically from the substrate. In view of this, in order to obtain a high Q factor and reduce spurious responses, this paper proposed the air gap type resonator using the sacrificial layer etching. The thickness of the AlN thin film used for piezoelectric thin film of Air-gap FBAR is 1um. Pt/Ti with 3000Å/300Å thickness is used as the top and bottom electrode. The device has a resonance frequency of 1.2GHz, and S11-paparameter of -25dB is also obtained.

In this study, highly C-axis oriented AlN thin films stacked upon Al bottom electrode on Si and Glass substrate are deposited with Reactive RF magnetron sputtering Technique. Three different sputtering systems were utilized to evaluate the optimized growth parameters. Room temperature growth was applied to the all system. During thin film growing , the substrate bias condition, sputtering work pressure, sputtering power and the N2 concentration are those key parameters to be adjusted in order to gain smooth surface morphology and highly C-axis prefer orientation AlN thin films. The crystallography of the deposited films was analyzed by x-ray diffraction (XRD). Film surface morphology was characterized by scanning electron microscopy (SEM). Meanwhile, transmission electron microscopy (TEM) was adopted to observe the microstructure and determine the grain size of the film. The results of the XRD patterns showed that in a 17cm long sputtering working distance condition, the AlN (002) can be obtained and the peak intensity can be increased when the sputtering power was fixed meanwhile reduced the working pressure and applied the negative bias on the substrate. The surface morphology can be improved with long working sputtering distance. The micrography of the TEM reveals that there is a transition region between Al metal and AlN film. Fine column structures can be observed in the initial growth stage. The size of the grain increased as the film became thicker. Strong AlN (002) ring pattern was obtained from the region of the top of the film. It indicates that the AlN (002) will not appear till the thickness of the film reach the critical thickness.

The solidly mounted resonator (SMR) is constructed of a Bragg reflector and a piezoelectric layer AlN. In order to obtain an appropriate SMR for the high frequency communication applications and high sensitivity bio-sensor applications, the Bragg reflector, the AlN, and the loading effect have been investigated thoroughly. The thesis presents the influences of surface roughness of the Bragg reflector and materials¡¦ selection on the resonance characteristics of an SMR. Three combinations of thin films, AlN/Al, Mo/Ti, and Mo/SiO2, are adopted. Originally, an AlN/Al multi-layer is used as the Bragg reflector. The poor surface roughness of this Bragg reflector results in a poor SMR frequency response. To improve the surface roughness of Bragg reflectors, a Mo/Ti multi-layer with a similar coefficient of thermal expansion is adopted. By controlling deposition parameters, the surface roughness of the Bragg reflector is improved. Finally, a material combination of Mo/SiO2 with high acoustic impedance ratio of 4.7 is adopted. Better resonance characteristics of SMR are obtained. The experimental results show a distinct resonance phenomenon around 2.5 GHz and excellent noise restraint. Afterwards, a ¼£f mode SMR is experimentally realized. The selection of high and low acoustic impedance for the first layer beneath piezoelectric layer results in the ¼£f mode and ½ £f mode resonance configurations, respectively. The coupling coefficient Keff2 of 6.9% is obtained, which is in agreement with the theoretical analysis. Following, the theoretical analysis upon the dual mode frequency-shift was characterized, and a modified formula was carried out. The c-axis tilted angle of AlN was altered as well as the various mass loading on the SMR. Based on the experimental results, the dual resonance frequencies showed a nonlinear decreasing trend with a linear increase of the mass loading. Furthermore, the ratio of the longitudinal resonant frequency to the shear resonant frequency remained at a range around 1.76 despite the various c-axis tilted angles of AlN and gradual mass loading on the SMR. The electromechanical coupling coefficient, keff2, of the shear resonance rose with the increase of the c-axis tilted angle of AlN. However, the longitudinal resonance fades away with the AlN c-axis tilted angle, and the quality factor of the longitudinal resonance decreases. Finally, the dual mode resonances are improved by tilting the off-center substrates toward the sputtering source and successfully enhance the longitudinal resonance while preserve the shear resonance at the same time. Not only the shear resonance for the liquid-based sensing application, but also an outstanding longitudinal resonance could be obtained. The practicability of the dual-mode resonator is extended for the applications of high frequency wireless communication and high sensitivity bio-chemical sensors.

In this study, the ladder-type filters based on back-etched thin film bulk acoustic resonator (TFBAR) were fabricated with several patterns to investigate the influence on their frequency responses. The highly c-axis oriented ZnO films were deposited on silicon substrates by reactive RF magnetron sputtering. The optimal two-step deposition temperature for ZnO films is 100 ¢J, which is obtained by means of SEM AFM, and XRD analysis. According to the experimental results, it leads to good resonance responses as TFBAR filters are fabricated with the patterns of large resonance area, two stages and the ratio of shunt/series resonance area is equal to two. Herein, conventional thermal annealing (CTA) was adopted to improve the frequency responses of TFBAR filters. Because CTA treatment can release stress and improve surface roughness of ZnO and Pt films, it enhances the frequency responses of TFBAR filters. The optimal CTA treatment temperature for TFBAR filters is 400 ¢J. Finally, TFBAR filters show the good performances with insertion loss of -8.138 dB, band rejection of 10.9 dB and bandwidth of 37.125 MHz.

On the toughening of bulk metallic glasses (BMGs), successful results in the phase-separated Zr63.8Ni16.2Cu15Al5 BMG have achieved compressive ductility over 15% through the computational-thermodynamic approach. In this study, the phase-separated Zr63.8Ni16.2Cu15Al5 BMG was compressed to nominal strains of 3%, 7%, and 10% at low strain rates (~10-4 s-1) and the results demonstrated that the BMG exhibited apparent uniform deformation initially, followed by visible local shear bands development. Afterwards, a single shear along the principal shear plane was soon developed and mainly dominated the whole deformation process. The principal shear contributed more than 2/3 of the overall plastic strain until failure. It was also found that the local shear strain varied along the principal shear plane and decreased monotonically from the shear band initiation site. Subsequently, in-situ compression experiments were conducted to monitor the change of sample shape during deformation in order to properly correlate with the stress-strain curve. The observed images showed that there was a one-to-one correspondence between the intermittent sample sliding and flow serration in the plastic region of stress-strain curve. Further investigations on flow serration were conducted on the Pd40Ni40P20 BMG through the compression experiments equipped with high-sensitivity strain gauges directly attached to two opposite sides of the test sample. There was an accompanied displacement burst when a shear band starts to propagate during deformation and this displacement burst would be accurately captured by the high-sensitivity strain gauges. Based on the displacement-time profile for one serration, shear-band propagating speed can be estimated and found to be insensitive to the applied strain rates (or the applied crosshead speeds). The disappearance of flow serration at high strain rates should be a result that the signal of displacement burst was overwhelmed by the applied strain rate. Using the shear strain rate data, the measured viscosity within a propagating shear band was found to be relatively low, which is in similar to the viscosity values reported in the supercooled liquid region during homogeneous deformation. In comparison with shear band propagation in the brittle Mg58Cu31Y6Nd5 and Au49Ag5.5Pd2.3Cu26.9Si16.3, moderately ductile Cu50Zr43Al7 and Pd40Ni40P20, and highly ductile phased-separated Zr63.8Ni16.2Cu15Al5 systems, the ductility of BMGs appears to be closely related to the dynamics during shear band propagation. The more ductile in nature the metallic glass is, the slower the shear band propagating speed would become. We also made attempts to investigate the shear band propagation in the porous Mo particles reinforced Mg58Cu28.5Gd11Ag2.5 bulk metallic glass composites (BMGCs) with up to 10% compressive failure strain. It was found that flow serration was absent in the stress-strain curve. Using high-sensitivity strain gauges, no distinct displacement burst was detected in the displacement-time profile. The diappearance of flow serration for the current porous Mo particles reinforced Mg58Cu28.5Gd11Ag2.5 BMGC is apparently associated with the lack of long-range shear band propagagtion. By employing the approach of separating the homogeneous amorphous matrix into many individual compartments, only short-range shear band propgagation is possible in the current Mg-based BMGC. An effective free spacing considering the spacing between two porous Mo particles and porous Mo particle size was applied to interpret the development of shear band propagation and is a useful indicator for the design of BMGC with high ductility.