從微藻提煉的生物燃料，是化石燃料和其他生物燃料的優良替代品。藻類生物燃料屬碳中性，因為微藻為光自養生物，能經光合作用吸收二氧化碳，並將之轉化成碳氫化合物和脂肪。碳氫化合物和脂肪可用以提煉生物燃料。此外，微藻可以吸收廢水中的污染物作生長的營養，同時作污水處理。 / 本研究項目的目的為透過下述方法，降低藻類生物燃料的生產成本，並提高藻株的脂肪含量： (1) 篩選可以在污水自養培育，並有高產油量的微藻菌株，(2) 以兩階段培養方法，用處理過的污水作培養，從而提高油脂產，(3) 透過微藻毒理測試，和水質化學分析，研究處理後的污水中影響微藻生長的污染物和有毒物質。 / 這個研究中使用從沙田污水處理廠收集的二級處理污水，其水質亦被研究。幾種微藻菌株分別為小球藻 (Chlorella pyrenoidosa)，叢粒藻 (Botryococcus braunii) 和微綠球藻 (Nannochloropsis oculata)，從鰂魚池水分離出的小球藻 (Chlorella sp.1)，及兩種從處理污水中分離出的小球藻(Chlorella sp. 2, Chlorella sp. 3)。微藻菌株分別在培養基和處理污水中培養，並比較在兩種情況下的脂肪，脂肪酸，碳水化合物，蛋白質含量，生物質量和總有機碳。結果發現，雖然經處理的污水中營養成分非常低 (<0.11 mg / L活性磷，<9.68 mg / L硝酸根，<0.5 mg / L鉀離子)，所有研究的微藻菌株都能存活。在兩階段培養法下，首先以「氮含量充足階段」(培養基)提高生物質量，然後以「氮含量不足階段」(經處理污水) 培養，培養成本可以降低，同時提高脂肪生產率。在兩階段培養法下，叢粒藻的脂肪生產率比在人工培養基和經處理污水高2.6倍和7.13倍。 / 沙田污水處理廠處理的污水水質良好，並無驗出有害重金屬，雙酚A(BPA)，四溴雙酚A(TBBPA)和2,3,7,8-四氯二苯並二噁英(TCDD)。從藻類產生的生物燃料將不含有重金屬。 / 在這個研究中的叢粒藻 (Botryococcus braunii)，微綠球藻 (Nannochloropsis oculata)和小球藻 (Chlorella sp.1)都可以容忍雙酚A(BPA)，四溴雙酚A(TBBPA)，二氯苯氧氯酚 (TCS)和2,3,7,8-四氯二苯並二噁英(TCDD)。他們可以培育在其他來源的經處理污水。 / 利用經處理污水於兩階段培養法，是一種新的、更經濟的增加微藻油脂產量方法，亦可以配合任何其他方法，以減低藻類生物燃料的製造成本。 / Biofuel from microalgae can be an excellent substitute of fossil fuel and other biofuels. Algal biofuel is carbon neutral as microalgae are photoautotrophic. Through photosynthesis, microalgae can capture and convert carbon dioxide to hydrocarbons or lipids which can be used for biofuel production. Besides, microalgae can use pollutants from wastewater as nutrients for growth, which can serve as a wastewater treatment process. / The aims of the project are to lower the cost of algal biofuel production and boost up lipid content of algal strains by (1) screen a microalgal strain that can be cultivated in treated sewage autotrophically and give high oil yield, (2) use two phase cultivation, with treated sewage as medium, to boost up lipid productivity, (3) investigate heavy metals and some organic pollutants that may exist in treated sewage and can affect algal growth by performing algal toxicity test and chemical analysis of treated sewage. / The secondarily treated sewage used in this project was collected from the Sha Tin Sewage Treatment Works. The quality of the secondarily treated sewage was monitored. Chlorella pyrenoidosa, Botryococcus braunii and Nannochloropsis oculata from commercial source, and Chlorella sp. 1 isolated from tilapia fish pond water, and two species of algae, Chlorella sp. 2 and Chlorella sp. 3, isolated from treated sewage were investigated. Microalgal strains are compared by investigating the content of lipid, fatty acid, carbohydrate, protein, biomass and total organic carbon when cultivated in culture medium and treated sewage. Results found that although nutrients in treated sewage were very low (<0.11 mg/L reactive phosphorus, <9.68 mg/L nitrate and <0.5 mg/L potassium ion), all the microalgae investigated could grow reasonably well. Using two phase cultivation, with an initial nitrogen sufficient phase (artificial media) for biomass production, followed by nitrogen limitation phase (treated sewage), cost of cultivation could be reduced and the overall lipid productivity could be increased. Under the two phase cultivation, the lipid productivity of Botryococcus braunii was 2.6 and 7.13 fold higher than cultivated in artificial medium and treated sewage respectively. / Treated sewage from the Sha Tin Sewage Treatment Works was in good quality without harmful concentrations of heavy metal and BPA, TBBPA and TCDD. The microalgae could not absorb or adsorb significant amount of the harmful substances and the algal biofuel produced would not contain heavy metals. All the microalgae investigated in this project could tolerate BPA, TBBPA, TCS and TCDD. They could be cultivated in treated sewage from other sources. / Two phase cultivation using treated sewage is a new way for increasing lipid productivity from microalgae economically and can be combined with any other means for producing algal biofuel with lowest cost. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Kwan, Ka Ki. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 104-113). / Abstracts also in Chinese. / Acknowledgements --- p.i / Abstract --- p.iii / 摘要 --- p.Vi / Table of Contents --- p.viii / List of Figures --- p.Xii / List of Plates --- p.Xvi / List of Tables --- p.xviii / Abbreviations --- p.xx / Chapter 1. --- General introduction / Chapter 1.1 --- Fossil fuel, the major energy source nowadays --- p.1 / Chapter 1.2 --- Disadvantages of using fossil fuel --- p.3 / Chapter 1.3 --- Biofuel --- p.5 / Chapter 1.4 --- Disadvantages of traditional biofuel production --- p.8 / Chapter 1.5 --- Characteristics of microalgae --- p.9 / Chapter 1.6 --- Biofuel from microalgae --- p.14 / Chapter 1.7 --- Nutrients for microalgae related to lipid production --- p.18 / Chapter 1.8 --- Current research on algal biofuel --- p.19 / Chapter 1.9 --- Two phase cultivation as a new way for lipid production --- p.24 / Chapter 1.10 --- Objectives --- p.24 / Chapter 2. --- Biofuel production under two phase cultivation with artificial medium and treated sewage / Chapter 2.1 --- Introduction --- p.26 / Chapter 2.2 --- Materials and Methods --- p.28 / Chapter 2.2.1 --- Algal strains collection and isolation --- p.28 / Chapter 2.2.2 --- Artificial culture media --- p.29 / Chapter 2.2.2.1 --- Bristol’s Medium (BM) --- p.29 / Chapter 2.2.2.2 --- Modified Bold 3N medium (MBM) --- p.31 / Chapter 2.2.3.3 --- F/2 medium (F/2) --- p.33 / Chapter 2.2.3 --- Water quality of treated sewage --- p.33 / Chapter 2.2.3.1 --- Chemical and biological condition --- p.34 / Chapter 2.2.3.2 --- Total organic carbon and total nitrogen (TOC/TN) --- p.35 / Chapter 2.2.3.3 --- Reactive phosphate --- p.35 / Chapter 2.2.3.4 --- Nitrate --- p.37 / Chapter 2.2.3.5 --- Ammonia --- p.39 / Chapter 2.2.3.6 --- Metal elements --- p.40 / Chapter 2.2.4 --- Cultivation conditions --- p.40 / Chapter 2.2.5 --- Growth monitor of microalgae in artificial medium and treated sewage --- p.41 / Chapter 2.2.6 --- Comparison of microalgae cultivated in artificial media and treated sewage --- p.42 / Chapter 2.2.6.1 --- Large scale cultivation --- p.42 / Chapter 2.2.6.2 --- Cell morphology --- p.43 / Chapter 2.2.6.3 --- Cell harvesting --- p.44 / Chapter 2.2.6.4 --- Dried biomass --- p.44 / Chapter 2.2.6.5 --- Lipid content --- p.45 / Chapter 2.2.6.6 --- Fatty acid profile --- p.46 / Chapter 2.2.6.7 --- Extraction of carbohydrates and protein --- p.48 / Chapter 2.2.6.8 --- Carbohydrate content --- p.48 / Chapter 2.2.6.9 --- Protein content --- p.49 / Chapter 2.2.7 --- Two phase cultivation --- p.50 / Chapter 2.2.8 --- Statistical analysis --- p.50 / Chapter 2.3 --- Results --- p.51 / Chapter 2.3.1 --- Water quality of treated sewage --- p.51 / Chapter 2.3.2 --- Nutrient contents in artificial medium --- p.54 / Chapter 2.3.3 --- Growth of microalgae in artificial medium and treated sewage --- p.54 / Chapter 2.3.3.1 --- Cell morphology and cell size --- p.57 / Chapter 2.3.3.2 --- Biomass --- p.59 / Chapter 2.3.3.3 --- Lipid content --- p.61 / Chapter 2.3.3.4 --- Fatty acid profile --- p.63 / Chapter 2.3.3.5 --- Carbohydrates content --- p.66 / Chapter 2.3.3.6 --- Protein content --- p.67 / Chapter 2.3.4 --- Two phase cultivation --- p.69 / Chapter 2.4 --- Discussion --- p.74 / Chapter 2.4.1 --- Water quality of treated sewage and nutrients in artificial medium --- p.74 / Chapter 2.4.2 --- Growth of microalgae in artificial medium and filtered treated sewage --- p.75 / Chapter 2.4.3 --- Microalgae cultivated in artificial media and treated sewage --- p.76 / Chapter 2.4.4 --- Two phase cultivation --- p.81 / Chapter 3. --- Possible toxic effect on algal growth from chemicals in sewage / Chapter 3.1 --- Introduction --- p.84 / Chapter 3.2 --- Materials and methods --- p.85 / Chapter 3.2.1 --- Analysis of dissolved metals by ICP --- p.85 / Chapter 3.2.2 --- Organic compounds --- p.86 / Chapter 3.2.3 --- Algal bioassay --- p.87 / Chapter 3.3 --- Results --- p.88 / Chapter 3.3.1 --- Dissolved metals and metalloids --- p.88 / Chapter 3.3.2 --- Organic compounds --- p.88 / Chapter 3.3.3 --- Algal bioassay --- p.91 / Chapter 3.4 --- Discussion --- p.97 / Chapter 4. --- Conclusion and future prospectives --- p.99 / Chapter 4.1 --- Summary --- p.99 / Chapter 4.2 --- Genetic engineering --- p.100 / Chapter 4.3 --- Further study --- p.102 / Chapter 4.4 --- Conclusion --- p.102 / Chapter 5. --- References --- p.104

投影機相機(projector camera)系統近年相當流行，主要原因是它能夠靈活地展示影像，使用戶有更大的自由度作出操作。手提式投影機的技術在過往幾年急速發展、漸見成熟，知名的家用電子産品生産廠閱始推出内置迷你投影機的手機和攝影機。另一方面手機的運算能力正急劇地提升，它們多都配置不同種類且功能强大的周邊設備。 / 本論文提出並討論一種基於現場可编程邏輯閘陣列(Field Programmable Gate Array, FPGA),並適用於嵌入式系统的特殊處理器。該特殊處理器專門處理來自相機的資料串流，透過一系列的象素圖像處理運算如圖像梯度和高斯模糊，去找出相中物件的邊緣，藉此分擔微處器在運算上的負擔。實驗結果明這特殊處理器可實現於低端的FPGA上並和普遍的微處器一起運作。 / 本論文第二個探討的主題是一個利用多模卡爾曼濾波器(Multiple Model Kalman Filter)的直線追踪器，並利用多個直線追踪器去作投影面板的追踪。利用卡爾曼濾波器只需要很低的運算能力的優點,我們的直線追踪器在嵌入式系统實測時能達到每秒200幀的速度。多模卡爾曼濾波器在實驗中有滿意的成績並較單卡爾曼濾波器和擴展卡爾曼濾波器優異。 / Projector-camera (ProCam in short) systems are getting very popular since the user can change the display area dynamically and enjoy more freedom in handling the device. In recent years, the mobile projector technology is becoming mature and manufacturers are shipping mobile phones and digital cameras with projectors. On the other hand, the computation power of a cell phone had dramatically increased and the cell phones are accompanied with large number of powerful peripherals. / In this thesis, the possibility of making an embedded Projector-camera (ProCam) system is investigated. A ProCam system is developed by our research group previously and designed for desktop Personal Computers(PCs). The system uses computer vision techniques to detect a white cardboard as the projection screen and uses particle filter to trace the screen in subsequent frames. The system demands a large computation power, unfortunately the power of low cost embedded system is still not powerful enough to implement the ProCam system.Therefore, specially designed hardware and computationally efficient algorithm are required in order to implement the ProCam system on an embedded system. / An FPGA based special processor to share the workload of the microcontroller in the embedded system is proposed and tested. This special processor will take the data stream of the camera as the inputs and apply pixel-wise image operators such as image gradient and Gaussian blur in order to extract the edge pixels. As a result, the workload of the microcontroller in the embedded system is reduced. The experiments show that the design can be implement on a low-end FPGA with a simple microcontroller. / A line tracker using Multiple Model Kalman lter is also proposed in this thesis. The aim of this tracker is to reduce the time on tracking the board. Benet from the low computation requirement of Kalman filter, the proposed line tracker can run in 200 fps on our testing embedded system. The experiments also show that the robustness of the Multiple Model Kalman filter is satisfactory and it outperforms the line trackers using single Kalman filter or extended Kalman filter alone. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Fung, Hung Kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 115-124). / Abstracts also in Chinese. / Abstract --- p.ii / Acknowledgement --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation and Objective --- p.1 / Chapter 1.2 --- Contributions --- p.3 / Chapter 1.3 --- Thesis Organization --- p.5 / Chapter 2 --- Background --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Projector-Camera System --- p.8 / Chapter 2.2.1 --- Static Projector-Screen --- p.9 / Chapter 2.2.2 --- Dynamic Projector-Screen --- p.13 / Chapter 2.3 --- Embedded Vision --- p.15 / Chapter 2.4 --- Summary --- p.25 / Chapter 3 --- System Overview --- p.26 / Chapter 3.1 --- System Design --- p.26 / Chapter 3.2 --- Our Approach --- p.28 / Chapter 3.2.1 --- Projector-camera system --- p.28 / Chapter 3.2.2 --- Smart Camera --- p.31 / Chapter 3.2.3 --- Quadrangle Detection and Tracking Module --- p.32 / Chapter 3.2.4 --- Projection Module --- p.32 / Chapter 3.3 --- Extension --- p.33 / Chapter 4 --- Smart Camera --- p.34 / Chapter 4.1 --- Introduction --- p.34 / Chapter 4.2 --- Hardware Overview --- p.35 / Chapter 4.3 --- Image Acquisition --- p.40 / Chapter 4.4 --- Image Processing --- p.42 / Chapter 4.4.1 --- RGB-to-Gray Conversion Module . --- p.44 / Chapter 4.4.2 --- Image Smoothing Module --- p.45 / Chapter 4.4.3 --- Image Gradient Module --- p.49 / Chapter 4.4.4 --- Non-maximum Suppression and Hysteresis Thresholding --- p.53 / Chapter 4.5 --- Summary --- p.55 / Chapter 5 --- Quadrangle Detection and Tracking --- p.57 / Chapter 5.1 --- Introduction --- p.57 / Chapter 5.2 --- Line Feature Extraction --- p.61 / Chapter 5.3 --- Automatic Quadrangle Detection --- p.62 / Chapter 5.4 --- Real-time Quadrangle Tracking --- p.68 / Chapter 5.4.1 --- Line Tracker --- p.69 / Chapter 5.5 --- Tracking Lose Strategy --- p.76 / Chapter 5.6 --- Recover from Tracking Failure --- p.77 / Chapter 5.7 --- Summary --- p.77 / Chapter 6 --- Implementation and Experiment Result --- p.79 / Chapter 6.1 --- Introduction --- p.79 / Chapter 6.2 --- Smart Camera --- p.79 / Chapter 6.3 --- Line Tracking --- p.87 / Chapter 7 --- Limitation and Discussion --- p.101 / Chapter 7.1 --- Introduction --- p.101 / Chapter 7.2 --- Limitation --- p.101 / Chapter 7.3 --- Summary --- p.105 / Chapter 8 --- Application --- p.107 / Chapter 8.1 --- Introduction --- p.107 / Chapter 8.2 --- Portable Projector-Camera System --- p.107 / Chapter 8.3 --- Summary --- p.110 / Chapter 9 --- Conclusion --- p.112 / Bibliography --- p.115

This study was carried out on algal biofilms grown using rotating algal biofilm reactors (RABRs) with the aim of: i) characterizing their growth in terms of photosynthetic activity and morphology ii) evaluating their performance as a wastewater treatment option and a feedstock for biofuels production, and iii) examining the algal-bacteria interactions. A review of algal biofilm technologies currently employed in wastewater treatment processes was made to compare nutrient removal efficiencies, factors that influenced algal biofilm growth, and the different bioproducts generated from algal biomass. Consequently, research efforts were directed towards addressing pertinent issues identified in literature in order to optimize these systems for wastewater treatment and bioproducts production. Successful growth of algal biofilms in municipal wastewater and subsequent removal of nutrients from the wastewater was demonstrated. Photosynthetic and respiration rates observed with depth of the biofilm were influenced by the biofilm composition (single vs. mixed species), culturing conditions (laboratory vs. outdoor), orientation to the light, nitrogen availability (N-replete vs. N-deplete), and dissolved inorganic carbon availability (presence or absence of bicarbonate). Slight enhancement in lipid production was also observed as a result of nitrogen stress and bicarbonate addition. However, the accumulated lipids were not as much as expected or as reported in suspended cultures. Presence of bacteria positively influenced microalgae growth in the mixed cultures but the reverse was not true. In conclusion, photosynthetic activity and biofilm structure were characterized with methods developed for the algal biofilms in this study. For now, productivity of the algal biofilms needs to be maximized in order to fully utilize its potential as a biofuel feedstock and nutrient removal option. Further research on algae-bacteria interactions using species native to the wastewater grown algal biofilms is recommended.

No description available.

Laser cutting is one of the most important applications of laser in manufacturing industry; it is mainly used for sheet metal cutting. In laser cutting, performing real-time evaluation of laser cut quality is very important to the advancement of this process in industry. However, due to the dynamic nature of the laser cutting process specially when cutting ferrous alloys using oxygen as an assist gas, laser cut quality cannot be easily predicted; therefore, the quality inspection of the laser cut is performed by off line inspections of the edges of the metal by skilled operators. This methodology is carried out after the process and thus cannot maintain a good quality if the process performance is out of control. Therefore, the objective of the research project is to qualify and develop a sensor system that ensure fault recognition online and can automatically control the laser metal cutting process to achieve good quality cut. For the realization of this objective the following has been done: - study the relationship between process parameters and cut quality characteristics; - identify the best sensors that can be used to monitor the process; - design and develop an experimental setup to test the proposed sensors; - collect and analyze data from the proposed sensors and correlate them to specific cut quality characteristics (process state variables); - develop direct relationships between the process signals and cut quality; - develop appropriate strategy for process control; - design and develop an integrated monitoring and control system; - test and evaluate the proposed system using simulation. In this study, a new technique for the determination of cut quality of sheet steels under the CO2 laser cutting process has been established. It is based on on-line detection and post-processing analysis of light radiation and acoustic emissions from the cut kerf. Determination of machining quality during cutting is best done through the measurement of surface roughness and kerf widths, as these are the two parameters that vary in successful through cuts. These two quality parameters can further be correlated to the two dominant process parameters of laser power and cutting speed. This study presents an analysis of acoustic emissions and reflected light for CO2 laser cutting of steel plates, and discusses their use for the estimation of cut quality parameters of kerf width and striation frequency for mild steel plates of 3mm, 5mm, 8mm, and 10mm thicknesses. Airborne acoustic and light signals are acquired with a microphone and a photodiode respectively, and recorded with a PC based data acquisition system in real time. The signals are then analyzed to establish a correlation between the signals obtained and the cut quality achieved. Experimental evidence shows that the energy levels of acoustic emission signals (RMS analysis) can be used to maintain the cutting process under steady state condition. On the other hand, the light intensity signal fluctuates with a frequency that corresponds to the frequency of striations formed on the cut surface; therefore it can be used to regulate cutting speed and laser power to obtain an optimum cutting condition and best cut quality. The validity of the proposed control strategy was tested experimentally by simulating the variations of cutting speed and examining their effect on the signals. So far, the prototype used for experimentation has been successful in providing correct information about cut quality in terms of striation frequency, and also about the state of the process where the microphone signal was successful in determining system failure or improper cutting conditions. A microprocessor based control system utilizing the PID control algorithm is recommended for the implementation of the control strategy. The implementation requirements of the proposed system for industrial use are then discussed. A new setup for the coaxial monitoring of CO2 laser cutting using a photodiode is proposed to enhance the quality of the signal and also to protect the photodiode from the harsh cutting environment. It is also proposed that an open control architecture platform is needed to enhance the integration of the proposed process control functions. Conclusions and future research directions towards the achievement of Autonomous Production Cell (APC) for the laser cutting process are then given.

Electromagnetic microactuators with permanent magnets have many potential applications such as micro-energy scavengers, microswitches, micromirrors and microfluidics. However, many electromagnetic microactuator designs utilize either external permanent magnet or external coil, which do not allow tight integration to other MEMS components and further miniaturization. Furthermore, all of the available permanent magnet microfabrication technologies have some drawbacks and improvements are required. Thus the integrated monolithic electromagnetic microactuator is investigated in this project. The three main components of the electromagnetic actuator have been investigated separately. A novel microfabrication technology called ???Template printing???for the fabrication of polymer bonded permanent magnet has been investigated and developed. It is based on ???Screen printing??? which has its drawbacks on alignment accuracy and poor line definition. This is eliminated in ???Template printing??? by photolithography of the photoresist template. The shape and location of the permanent magnet is defined by the template. A new approach based on the filling of dry magnetic powder and vacuum impregnation has been developed to form the polymer bonded permanent magnet. This allows the use of short pot-life matrix material and the elimination of homogenous mixing. A monolithic electromagnetic microactuator has been fabricated successfully. It consists of a 2-layer planar copper microcoil, surface micromachined polyimide beam and Strontium ferrite/EPOFIX permanent magnet (diameter of 460 ??m and 30 ??m thickness). Large deflection in excess of 100 ??m at 35 mA driving current and magnetic force of 0.39 ??N/mA have been achieved. It compares favourably with other much larger electromagnetic actuators that have been reported. ???Template printing??? has the potential of being a low temperature batch process for the microfabrication of thick polymer bonded permanent magnets with high magnetic properties and low residual stress. The fabrication consistency and the quality of template printed magnet can be improved in future studies.

Gac (Momordica Cochinchinensis Spreng or Muricia Cochinchinensis Spreng) is an indigenous fruit of Vietnam, commonly used as a colourant in traditional dishes. Recent studies showed that this fruit had a high carotenoid content, especially lycopene and β-carotene. These carotenoids are currently in high demand as they are natural antioxidants to prevent and treat cancers. Over the last ten years some new products from Gac fruit have been found on the market but the cultivation and consumption of the fruit is still limited. Gac is harvested seasonally and the post harvest processing has not been well developed. To make the best use of the valuable substances in Gac, this project investigated some processing methods to make Gac powder and developed the product quality analyses, potentially applicable to local small-scale manufacture. In order to evaluate the efficiency of the Gac powder process and some of the most important qualities of the Gac powder products, the analytical methods to determine lycopene and β-carotene were developed and validated in this project. The new HPLC-based method included a liquid-liquid extraction, followed by a solid phase extraction before the analysis. Both newly- developed HPLC and SP methods exhibited a high extraction yield, good recovery and reproducibility. Compared with the HPLC, the SP method gives higher mean values and standard deviations, but it is quicker, simpler, less expensive and still reliable for industrial applications due to the use of less toxic solvents. The production of powder from Gac fruit included two main stages: seed removal and aril dehydration. Derived from the same drying operation, the enzymatic-treated Gac powder had a lower carotenoid content compared to the heat-treated powder. The Gac powder produced by the freeze-drying method had the highest carotenoid level and brightest colour. Finally the orange-red Gac powder with high carotenoid content was added to some foods as a colorant and nutrient supplement to illustrate its applications. The colours of foods were significantly improved and the carotenoid contents were increased after processing, indicating a potential market for the Gac powder. / Master of Science (Hons)

Extensive brackishwater aquaculture, which is a dominant land-based aquaculture system in Indonesia, has experienced variable success in most farming locations in the country due to poor understanding of spatial assessment of environmental factors and rudimentary site selection criteria. Despite tremendous potential, the application of GIS and remote sensing in spatial assessment has tended to focus on Boolean (Crisp) logic that is often unable to effectively handle the complexity and spatial variability of key environmental factors for the development of aquaculture. This study explored the possibility of integrating fuzzy logic techniques into GIS and remote sensing technology to generate more robust mapping protocols in aquaculture, compensating for the disadvantages of the Crisp method. Two models were developed in two different provinces in Indonesia to spatially assess soil and hydrological constraints on extensive brackishwater aquaculture. The soil assessment focussed on acid sulfate soils (ASS) and sandy-textured sediments in Aceh, and the hydrological study focused on investigating important wave parameters that influence the suitability of coastal areas for siting extensive pond units in South Sulawesi. The study showed that fuzzy-based classification methods, integrated into the image analysis, was highly effective in identifying existing and potential pond areas for extensive brackishwater aquaculture compared to the best result of the commonly used Crisp method. By addition of one or more key environmental variables of ASS into the fuzzy-classified existing and potential ponds areas, a very robust predictive tool to identify potential ponds areas affected by ASS in Kembang Tanjung, Aceh was developed. A more detailed assessment of ASS developed in this study also successfully highlighted the severity of sandy-soils and identified them as another key soil variable that has and will severely impact on pond productivity. The second model developed by the study enables fuzzy logic to be integrated into GIS to predict the possible areas impacted by moderate to high energy wave conditions and possible ways of minimising their direct and indirect impacts. The models developed in this study were shown to work well in both study sites and can be applied elsewhere. The mapping outputs are easy to interpret even by stakeholders with no prior training in map reading. Overall, the models have the potential to reduce planning errors and to improve decision making in aquaculture provided that quality data sources are used.

Certain applications have recently appeared in industry where a traditional bar code printed on a label will not survive because the item to be tracked has to be exposed to harsh environments. Laser direct-part marking is a manufacturing process used to create permanent marks on a substrate that could help to alleviate this problem. In this research, a 532 nm laser was utilized to create a direct-part marked Data Matrix symbol onto carbon steel substrates with different carbon content. The quality of the laser marked Data Matrix symbol was then evaluated according to the criteria outlined in the ISO/IEC 16022 bar code technology specification for Data Matrix. Several experiments were conducted to explore the effects that different parameters have on the quality of the laser direct-part marked symbols. First, an experiment was conducted to investigate the effect of two different laser tool path patterns. In later experiments, parameters such as type of carbon steel, percent of laser tool path overlap, profile speed, average power and frequency were found to have significant effects on the quality of laser direct-part marked Data Matrix symbols. The analysis of the results indicated that contrast and print growth were the critical standard performance measures that limited laser direct-part marked Data Matrix symbols from achieving a higher final grade. No significant effects were found with respect to other standard performance measures (i.e., encode, axial uniformity, and unused error correction). Next, the experimental data collected for contrast and print growth was utilized as training, validation and testing data sets in the modeling of artificial neural networks for the laser direct-part marking process. Two performance measures (i.e., mean squared error and correlation coefficient) were employed to assess the performance of the artificial neural network models. Single-output artificial neural network models corresponding to a specific performance measure were found to have good learning and predicting capabilities. The single-output artificial neural network models were compared to equivalent multiple linear regression models for validation purposes. The prediction capability of the single-output artificial neural network models with respect to laser direct-part marking of Data Matrix symbols on carbon steel substrates was superior to that of the multiple linear regression models. / Graduation date: 2004

Laser ultrasonics can be used to nondestructively evaluate structures to determine the existence and location of surface and interior flaws. The goal of this research was to determine if laser ultrasonic techniques can be applied to the inspection of aluminum plate. titanium tubes, and large welded plate structures. The research was carried out with a Q-switched pulsed ruby laser emitting light of 694 nm wavelength. Ultrasonic waves were experimentally generated and recorded in the aluminum plate and the titanium tube. A comprehensive literature study was completed to determine if the technique can be applied to welded structures. For the two experimental cases, the ultrasonic waves were received by a piezoelectric pinducer which was located on the opposite side of the plate. and on the outside of the tube. A digital oscilloscope captured the signals from the pinducer. The signals were then analyzed to determine echo spacing and frequency content. The physical characteristics of the laser pulse such as the energy and full-width-half-height and amplitudes were measured via a photodiode system and a calorimeter. The aluminum plate confirmed that the system was functioning properly, as the ultrasonic echoes that were generated matched the expected results from previous experimentation. The titanium tube data turned out to be difficult to interpret due to the complex geometry and mode conversion. The welding research showed that ultrasound can be used to identify many types of flaws in a welded joint. Currently, few researchers have applied the laser based ultrasound to flaw detection in finished welds, although several have looked at using the laser ultrasound as an input to a control system for a weld in progress. The literature research uncovered the need for further studies on the application of laser based ultrasound to flaw detection in completed welds. / Graduation date: 1997