The implantation of helium ions into lithium niobate produces a reduction in its refractive indices, due to radiation damage produced close to the end of the ion trajectories. This reduction can be utilised to form the boundaries of optical waveguides, which form the basis of any integrated optical circuit. Stripe waveguide fabrication using ion implantation has been demonstrated for the first time in this work. Firstly a buried damage layer was formed to define the depth of the waveguide, followed by additional implants around a gold mask to form the waveguide sidewalls. The gold mask was used to protect the guiding region during the latter implantation process. The waveguides were evaluated using the end-fire coupling technique to excite individual modes. Propagation loss and modal dimensions were determined experimentally for the fundamental mode of each guide, and it was shown that these properties are sensitive to both the ion energy of the wall implants, and the number of wall implants. Each of these two variables affects the propagation loss in the opposite sense to the other, and therefore the lowest propagation loss becomes dependant on the trade off between these two effects. The lowest loss of the waveguides presented in this thesis was found to be ~1 dB/cm, and it is expected that this figure may be further reduced by the optimisation suggested in the conclusions of this work. Additional results are presented which consider the electrooptic and photorefractive properties of ion implanted LiNbO3. Previous work of others suggested that the electrooptic effect would be considerably reduced in the implanted material, but the results were much more encouraging, showing a reduction of only ~20% in the r13 electrooptic coefficient. Furthermore, one of the most serious drawbacks of Ti:indiffused waveguides is the undesirable reduction of the output intensity due to the photorefractive effect, which has been shown not to affect the waveguides presented in this thesis.

No description available.

University of Macau / Faculty of Science and Technology / Department of Electrical and Computer Engineering

In this research work, a software and hardware prototype for real—time 3D visualisation is developed. The proposed system takes two input videos to interpolate virtual in—between views, which are then combined into 3D videos after processing for viewing on a 3D monitor. The core section of this research work is based on view morphing, a type of image based rendering. The image based rendering is a technique used to render a scene from a number of source images. According to the knowledge of geometric information of captured scenes, the image based rendering technique can be classified into three categories: rendering without geometry, rendering with implicit geometry and rendering with explicit geometry. The view morphing technique, a subset of the second category, requires less geometric information and a few source images of captured scenes. These reduce the complexities of both computation and hardware configuration of the proposed system, moreover, the quality of interpolated virtual in—between views by view morphing technique is good enough for visualisation applications. In this thesis, the research work is presented from two aspects: the algorithmic and the system's points of view separately. The algorithmic development and optimisation consist of the procedures of automatically interpolating virtual in—between views from two source images. The work begun with two cameras calibration with the objective of finding out the geometric relationship in 3D space between the two cameras. Image rectification is followed to project two source images into two parallel planes. This enables to obtain physically valid virtual in—between views and also reduces the computational cost for correspondence estimation. Subsequently, stereo matching is applied to establish feature correspondences between the two rectified source images. A novel feature based correspondence estimation algorithm is proposed to raise the level of the computational efficiency and the reliability. After that, interval interpolation is used to synthesise virtual in—between views. Finally, image derectification is applied to obtain final interpolated virtual in—between views. A novel pseudo real—time 3D visualisation system is proposed in the system development and optimisation. The proposed system has been developed using the TI (Texas Instruments) DM642 EVM board which is a standalone Digital Media Processing board. The system also includes a stereo video capture module consisting of two PAL cameras and the X3D-19 DISPLAY AD 3D display unit for visualisation of 3D video output. The core algorithm utilises images captured from the cameras and generates 6 virtual in—between views using interpolation techniques. The combined views (eight views of 2D images) are displayed on the 3D monitor using a proprietary method developed specifically for X31) monitors. The advantage of the proposed system is that real 3D impressions are able to be visualised in front of the 3D monitor in near real—time without any special glasses. The proposed system has been evaluated on a number of real scenes. The experimental results indicate that the performance of the proposed 3D visualisation system is about 4.7 FPS.

A dissertation submitted to the Faculty of Education in partial fulfilment of the requirements for the degree of Master of Education in the Department of Mathematics, Science and Technology at the University of Zululand, South Africa, 2015 / The present study examines teachers’ attitudes towards selected challenges in the teaching of Mathematics in the Maphumulo Circuit. The was designed to determine teachers’ attitudes towards the selected challenges brought about by additions or introduction of new chapters to the FET Mathematics curriculum; to establish the relationship, if any, between teachers’ attitudes and the following variables: gender, age in years, academic qualifications, professional qualifications, post level, teaching experience in years and employment status; to establish the role played by the status of resources in influencing teachers’ attitudes towards the selected challenges, that is, the introduction of new chapters to the FET Mathematics curriculum; and to mention reasons for teachers’ happiness or unhappiness with the newly introduced chapters to the FET Mathematics curriculum. To achieve the aim and objectives of the study a Likert 5-point scale questionnaire was, checklist, open-ended questions and quantitative data analysis methods were administered to a sample of one hundred Mathematics teachers in Maphumulo Circuit. The study results reveal that Mathematics teachers are negatively inclined towards the selected topics. The findings also show that gender, age, academic qualifications, professional qualifications, post level, teaching experience and employment status influence teachers’ attitudes towards the selected topics. The findings further reveal that teachers have serious problems regarding matters related to the shortage of teaching resources. Finally, the findings reveal that teachers are not happy with the newly introduced chapters to the FET Mathematics curriculum. The discussion of findings coupled with their implications is highlighted. The avenues for future research are indicated.

No description available.

In the last few decades, miniaturization has been in increasing demand in many applications. The miniature actuators should comprise high power-weight ratio while having a fast dynamic response, and high efficiency. In this thesis several approaches have been studied to develop a low pressure water hydraulic system driving a miniature rotary joint as the end-effecter. While the system was expected to have a cross sectional diameter of 15 mm, two prototypes were manufactured having cross sections of 12.5 mm X 13 mm (18 mm dia.) and 16 mm X 18 mm (24 mm dia.). The system involves a novel closed-circuit water hydraulic system in which a controlled volume of water supplied by a motor-cylinder pump drives the rotary joint cylinders (4 mm bore). The linear motion of these cylinders is converted to a rotational motion through a sliders-pulley mechanism. The rotation of an arm attached to this pulley is measured by a magnetic rotary encoder. The dynamic behaviour of the system was studied and the most important parameters have been modelled. This model has been utilized in the design of a model based feedforward (FFWD) controller which was added to a PID controller to enhance the position control of the rotary arm. Numerous experiments were conducted with the horizontal rotation of the rotary arm. The maximum error ( emax) recorded for a mixed input (a combination of rising and falling cycloidals of 120° and 60° with pause periods of 1 and 0.5 s) with a PID controller was 8.3° while with the addition of the FFWD term this dropped to 6.2°. The maximum root mean square error (RMSE) for the same trajectory has been 1.7° and 0.9° for PID and FFWD+PID controllers respectively. The steady state error (SSE) which was measured during a eycloidal input of 120° was recorded to be in the range of ±0.2° for both of the controllers. The robustness of the controllers was evaluated by adding a mass of 8.5 g to the end of the rotary arm which produced an un-modelled extra large inertia to the system dynamic when the arm rotating horizontally. Robustness of both controllers was demonstrated as the change in the main numerical performance indicators (RMSE, ernax, and SSE) were not remarkable. Another set of experiments performed with the rotary joint positioned vertically introduced with an un-modelled changing force. The numerical performance indicators were almost unchanged again. A comparison between the results of this thesis with the ones from the previous work in our laboratory by R. Sindrey indicates a significant improvement. / Thesis / Master of Applied Science (MASc)

Contrôleurs utilisés dans les systèmes autotestables pour le test des sorties combinatoires ou séquentielles. Conception des contrôleurs NMOS à partir de l'assemblage des cellules, des règles de conception pour celle-ci, et des hypothèses de pannes pouvant survenir. Les considérations pratiques sont basées sur des hypothèses de pannes analytiques

Circuit breakers are used in a power system to break or make current flow through power system apparatus. Reliable operation of circuit breakers is very important to the well-being of the power system. Historically this is achieved by regular inspection and maintenance of the circuit breakers. An automated online circuit breaker monitoring system is proposed to monitor condition, operation and status of high and medium voltage circuit breakers. By tracking equipment condition, this system could be used to perform maintenance only when it is needed. This could decrease overall maintenance cost and increase equipment reliability. Using high accurate time synchronization, this system should enable development of system-wide applications that utilize the data recorded by the system. This makes possible tracking sequence of events and making conclusions about their effect on-line. This solution also enables reliable topology analysis, which can be used to improve power flow analysis, state estimation and alarm processing.

VLSI circuits in nanometer VLSI technology experience significant variations - intrinsic process variations and variations brought about by transistor degradation or aging. These are generally embodied by yield loss or performance degradation over operation time. Although the degradation can be compensated by the worst-case scenario based over-design approach, it induces remarkable power overhead which is undesirable in tightly power-constrained designs. Dynamic voltage scaling (DVS) is a more powerefficient approach. However, its coarse granularity implies difficulty in handling finegrained variations. These factors have contributed to the growing interest in poweraware robust circuit design. In this thesis, we propose a Built-In Proactive Tuning (BIPT) system, a lowpower typical case design methodology based on dynamic prediction and prevention of possible circuit timing errors. BIPT makes use of the canary circuit to predict the variation induced performance degradation. The approach presented allows each circuit block to autonomously tune its performance according to its own degree of variation. The tuning is conducted offline, either at power on or periodically. A test pattern generator is included to reduce the uncertainty of the aging prediction due to different input vectors. The BIPT system is validated through SPICE simulations on benchmark circuits with consideration of process variations and NBTI, a static stress based PMOS aging effect. The experimental results indicate that to achieve the same variation resilience, proposed BIPT system leads to 33% power savings in case of process variations as compared to the over-design approach. In the case of aging resilience, the approach proposed in this thesis leads to 40% less power than the approach of over-design while 30% less power as compared to DVS with NBTI effect modeling.