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Thesis (M. Ing.)--University of Stellenbosch, 1997. / Bibliography. Also available via the Internet.

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ABSTRAT In this thesis, we focused on the fabrication and frequency-modulation of £f/4 mode dual-band solidly mounted resonators and filters. To accomplish the Bragg reflector, the RF/DC magnetron sputtering system with dual targets is adopted to deposit alternating layers of quarter-wavelength Mo and SiO2 thin films. We tune the fabrication parameters in accordance with the AFM measurement and achieve a low roughness of 2.9nm on a nine-layer reflector. The piezoelectric layer, aluminum nitride (AlN) thin films, is deposited on the Bragg reflector by means of reactive RF magnetron sputtering. We alter the distance between substrate and target is altered to deposit AlN with various c-axis tilting angle which results in longitudinal and shear acoustic waves at the same time. Furthermore, we use mass loading effect to modulate the resonance frequency and fabricate £k- ladder type filters. In various numbers of reflector layers, the optimum frequency response is obtained with return loss of -26dB, in a SMR on a 3.5 pair reflector. To investigate the relationship between longitudinal and shear resonance in different resonance frequency, we alter the c-axis tilting angle of AlN as well as various mass loading on the SMRs. Based on the experimental results, the ratio of longitudinal to shear resonance frequency remains a constant value despite various c-axis tilting angle of AlN and mass loading on the SMRs. In addition, the electromechanical coupling coefficient, Kt2, of shear resonance raises with the increase of c-axis tilting angle of AlN. Finally,we have successfully fabricated SMRs with frequency modulataion of 3,899.68 Hz-cm2/ng and £k-ladder type filters with 26 MHz bandwidth.

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Amorphous Mg-Cu-Y metallic glasses are established by density functional theory and simulated annealing method in this study. The mechanical properties of amorphous Mg-Cu-Y metallic glasses are investigated by molecular statics simulations for the nano-indentation and the nano-scratch process. In this study, some potential energy parameters are obtained by fitting for describing the Mg-Cu-Y system. The bulk modulus, the Young¡¦s modulus and X-ray structure of the Mg-Cu-Y system are calculated. Our results are within 10% error compared with experimental values, which prove the correctness of fitted potential parameters. For the cases of nanoindentations, the indentation force-displacement and the influenced depth are calculated. The mechanical properties are obtained are close to experimental results. The both ¡§slip vector¡¨ and Honeycutt-Andemen index (HA index) parameters are also used to study the deformation behavior and bond-type of a group of atoms. Our results indicate that the influenced depths can be affected by the tip indentation and the gather of copper atoms. The gather of copper atoms can provide the resistance and strengthen the mechanical properties of Mg-Cu-Y material. On the other hand, our results indicate that the amorphous structure of Mg-Cu-Y metallic glasses cannot be transferred to crystal structure during nano-indentation process by analysis of HA index. For the cases of nano-scratch, two different scratch depth (5Å and 15Å) are investigated to understand the understand the depth effect. the scratch force-displacement curve is also obtained. As the same with nano-indentation results, the scratch force will increase because the gather of copper atoms and provide the resistance.

Shipping industry belongs to an international business. It plays an extremely important role in the economic and trade development of a country, so it can be regarded as a symbol of extension of the national strength of a country. Besides, it earns a lot of foreign capital for the country, but never creates any negative effects to the society domestically, such as environmental protection, noise, congestion, and so on. This is something that other manufacturing industries are incomparable with. Especially that Taiwan is an island, Taiwan should be engaged in the studies of shipping business through the rich marine resources. Then, unlimited business opportunities and vitality must be brought to Taiwan, achieving the aspiration of and confidence in standing in Taiwan but looking far to the world. International marine transportation business can be divided into irregular bulk shipping and regular container shipping. Between them, irregular bulk shipping is mostly the loading of the bulk cargoes by one or two consignors in one whole vessel. It is almost a completely competitive market. In order to obtain the greatest profit through the unlimited shipping lines and cargo loading, the best business operation ways and the best vessel allocation should be selected. For regular container shipping, services are provided to a great number of consignors with fixed shipping lines, fixed anchoring harbors and fixed rate. The cost of refueling of shipping industry occupies an extremely high proportion of the variable cost of marine transportation. When the price of the international fuel rises continuously, the cost of fuel increases accordingly. Taking the international vessel-use fuel MF-180 for example, the market quotation of oil in Taiwan on Jan. 6, 1999 was US$74/MT. After that, the price rose continuously. Down to Oct. 2007, there appeared the market quotation of oil at above US$500/MT. According to the ¡§Medium Term Oil Market Report of International Energy Agency (IEA)¡¨ announced on Jul. 9, 2007, the whole world would face the shortage of oil supply in five years, and the oil price was estimated to be rising continuously. Bulk marine transportation is irregular shipping without the fixing of any regular shipping lines and cargo loading. If refueling is to be made to vessels, there should be more efficient estimation and decision on the refueling harbor, refueling volume and refueling cost so as to achieve the minimum variable cost and acquire the greatest profit. Through review of the literature about the refueling of voyages as well as the interviews with experts, the paper investigates the literature of the decision support system, and uses the prototype development method to complete the model construction and the analytical design of system, practically establish a prototype of refuel decision support system for bulk shipping, and provide the solutions of average sailing speed of voyages, refueling volume and refueling harbor. After the results are compared with those of the actual cases, the paper evaluates the effects of the decision support system. Through the users¡¦ feedback, the prototype is revised to increase the completeness of the system, which provides a reference for the bulk shipping proprietors in constructing a refueling decision support system in future.

The mechanical properties of the amorphous bulk metallic glassy (BMG) alloy, Mg58Cu31Y11, are examined by a non-traditional analytic method - nanoindentation scratch test. This thesis will discuss the influences of friction force, and fracture surface geometry on the BMG surface for load, depth of scratch, scratch velocity, and test temperature of the nano-scratch process. In this study, experimental factors, including load, depth of scratch, scratch velocity, and test temperature, are taken into consideration to investigate the effects of the friction force. And then, this research utilizes regression analysis to establish BMG machining experience formula. The significant parameters of the friction force on nano-scratch and the reliability of the prediction model are investigated by statistical software. According to the results, the friction force is nearly proportional to power of the load. The friction force exhibits a slightly dependence on the test temperature. Besides, the nano-scratch results show that the friction coefficient also increases as the load and test temperature increases. The results associated with the analysis of the variance can be practiced to assess the prominence among experimental factors. The analysis indicates that the load, test temperature play significant factors on the friction force. The results of the regression analysis using a statistical software can be applied to model the mathematical relationship between machining factors and friction force. It anticipates that the model is able to predict friction force over a wide variety of scratching conditions. The model is also proved in good agreement with experimental results.

Thin Film bulk acoustic wave devices have the advantages of low loss, low temperature coefficient of the resonant frequency, and high power handling. These excellent characteristics are suitable for the applications on high frequency communication systems. In this study, thin film bulk acoustic wave filters using the ladder-type filter and stacked crystal filter configurations were investigated. Platinum was chosen as the top and bottom electrodes. To improve the platinum adhesion on SiNx/SiO2/Si substrates, a seeding layer of titanium is used. Highly c-axis oriented piezoelectric zinc oxide thin films were deposited by two-step deposition method under room temperature. As resonant area decreases, the band rejection of ladder-type filter will increase. Because the resonant area decreased, the distance between signal and ground will increase the results in an increased insertion loss. On the other hand, stacked crystal filters have larger band rejection and less 3dB bandwidth, which are suitable for the application of narrow band filters.