The interocular transfer of simultaneously presented visual discriminations was examined in the pigeon (Columba livia) in several experimental situations. When trained monocularly on a jumping stand, there was no evidence of transfer to the other eye-hemisphere system of either pattern or colour discriminations using retraining and reversal learning measures as well as testing. This failure was not due to any obscuring of transfer consequent upon switching the occluder from one eye to the other, nor was there any suggestion of even a small amount of transfer of information from the trained eye to the untrained eye with extensive overtraining and decoupling trials. Binocular training on the jumping stand also revealed that some of the pigeons were learning a discrimination with only one eye in spite of the opportunity to learn with both eyes. When trained in a key pecking task, pigeons demonstrate perfect transfer. Testing revealed that this discrepancy in results is not due to the number of trials given in the two situations, to separation of the stimuli over a greater distance or by a partition, nor to the distance at which the pigeon makes a decision about which stimulus to approach. When the function of the retinal locus of the stimuli was examined, evidence was found in the literature and in my observations that the pigeons were using a different part of the retina when scanning the stimulus display in a key pecking task than on the jumping stand, even though the stimuli in the two situations were located in the same position relative to the bird's head. Specifically, in the key pecking tasks the red area of the retina, which serves the lower binocular portion of the retina, is used. On the jumping stand this area is not used to scan the stimuli. It was then possible to demonstrate a failure of transfer in a key pecking task and successful transfer on the jumping stand by simply manipulating whether the red area was used in scanning the stimuli. The results are discussed in terms of a consequence of binocular convergence from the red area, and when there is a failure of transfer, when the red area is not used, or prevented from being used, the stimuli fall within the monocular field where there is no necessity of later convergence from the two inputs. Active inhibition mechanisms also might serve to lateralize input to one hemisphere.

Plasma Immersion Ion Implantation has several unique advantages over conventional implantation, such as low cost, large area capability, non-line-of-sight features and high dose rate implantation. However, it is still far from use in routine production because of problems such as the ability to control the ion depth profile in targets, the ion dose and contamination. In this thesis, a PIII system has been systematically calibrated, and a computer simulation code for PIII has been developed in order to understand more clearly the physics of the PIII process and to optimise the experimental conditions. In the second part of this thesis, a new application of PIII has been explored, where the PIII technique has been used as a high dose-rate implant treatment to form amorphous silicon nitride/oxide films on both crystalline and amorphous silicon substrates. The electrical properties of these films have been characterized. It shows that low dose nitrogen/oxygen implantation leads to the modification of Schottky barrier heights or the introduction of charged defects in the materials. As the ion dose is increased, alloying effects take over, forming silicon nitride/oxide alloys. The a-SiNx:H films synthesized via PIII have electrical characteristics similar to those grown by PECVD, but a-SiOx:H has different electrical properties from a-SiNx:H.

Aerosol effects are one of the major uncertainties in assessing global climate change, ecosystem processes and human health. This is because they critically change the balance between the radiation entering and leaving the atmosphere, as well as influencing cloud formation and having direct effects on biological systems e.g. through the respiratory system. It is the direct radiative effects of aerosol that are the focus of this work. The Aerosol Optical Depth (AOD) is a measure of the extinction of radiation by aerosol throughout the depth of the atmosphere. It is wavelength dependent and is traditionally measured at a number of visible wavelengths, but there is little AOD data available at UV wavelengths especially in the UVB. The Brewer spectrophotometer makes direct sun measurements in the UV spectral range, which can in principle be used to calculate AOD at those wavelengths using a form of Beer's law. This work explores the capabilities of the Brewer for UV AOD measurements and applies the results to data from the Tropics and temperate mid-latitudes. Instrument specific weighting functions were tested for their ability to improve the AOD retrieval, but while they changed the partitioning of absorption between ozone and SO2, they had negligible effect on the resulting AOD. After correcting the existing Brewer software for AOD retrieval, data from Manchester UK were compared with independent measurements of AOD, and measurements from the Manchester instrument were also evaluated against a standard Brewer on location in Spain. The inter Brewer comparisons were consistent with differences of the order 6-10%, while comparison with independent methods was qualitatively consistent, but absolute differences were of the order 10-30%. This might partially be attributed to wavelength mismatches between the different methods, and assumptions in the various methods of calculating the AOD.Following the validation exercise the AOD was retrieved from Brewer instruments, using standard weighting functions, in Manchester from 2000- 2008 and Reading from 2003-2008. Based on this work in the UK, the method was then applied to data from Malaysia (1998-2007), where the climate is totally different to that of the UK. The AOD data obtained from the UK and from the Tropics have been compared. Kuala Lumpur, Malaysia gave the highest average AOD values probably due to it being a developing city with high pollution levels indicating a human impact on climate change. Brewer AOD measurements obtained at a narrow range of wavelengths were then used to calculate Angstrom parameters by applying Volz Method. The results, often generating a negative alpha, were deemed unreliable at the UK sites. This was largely attributed to the high solar zenith angle and low signal to noise of the direct sun measurement, exacerbated by a limited number of clear sky measurements available for the work. However, calculation of Angstrom parameters was more successful in Malaysia due to a low solar zenith angle, high intensity, and greater frequency of truly could free sky. Results indicated that aerosol particles in the capital Kuala Lumpur show a clear domination by fine mode. This domination is probably caused by urban pollution, mainly from road traffic, industrial and anthropogenic activities, which is consistent with a large capital city undergoing rapid development.Thus the capabilities and limitations of the Brewer spectrophotometer to provide both AOD data at UV wavelengths, and from those further aerosol properties, has been tested and demonstrated in two contrasting climatic regions. Air mass, limiting the UV signal, and stray-light within the instrument are two of the factors that limit the success of the Brewer for these measurements, which proved more reliable when the sun was high in the sky as in the Tropics.

The thesis presents a defocusing technique to extract bubble depth information. Typically, when a bubble is out of focus in an image, the bubble is ignored by applying a filter or thresholding. However, it is known that a bubble image becomes blurred as the bubble moves away from the focal plane. Then, this technique is applied to determine the bubble distance along the optical path based on the blurriness or intensity gradient information of the bubble. Using the image processing algorithm, images captured in three different experiments are analyzed to develop a correlation between the bubble distance and its intensity gradient. The suggested models to predict the bubble depth are also developed based on the measurement data and evaluated with the measured data. When the intensity gradient of the bubble is lower or when a bubble is located farther from the focal plane, the model can predict the distance more accurately. However, the models show larger absolute and relative error when the bubble is near the focal plane. To improve the prediction in that region, another model should be considered. Also, depth of field analysis is introduced in order to compare three experimental results with different imaging setups. The applicability of the approach is analyzed and evaluated. / Master of Science / Gas and liquid measurements of two-phase flow are very challenging, but it has become more important because of many industrial applications such as chemical, petroleum, and energy industries. Many two-phase flow measurement techniques have been developed and utilized for different flow conditions such as fiber optic probe, multi-sensor conductivity probe, wire-mesh sensor, as x-ray densitometry, particle image velocimetry (PIV), and optical imaging. With the development of the technology, the imaging technique can provide better spatial and temporal resolutions as well as image processing speed has improved greatly. In this study, the imaging and defocusing techniques are combined and used to extract bubble depth information. An image processing algorithm has been developed to process bubble images captured by high speed cameras. By measuring the blurriness or intensity gradient information of the bubble, the bubble distance along the optical path is determined. Based on the measurement data, mathematic models are developed to predict the bubble depth. In addition, depth of field analysis is suggested to compare three experimental results with different imaging setups. The applicability of the approach is analyzed and evaluated.

Three experiments were conducted to study the effect of an occluder on the accuracy of nearield depth perception in optical-see-through augmented reality (AR). The first experiment was a duplicate experiment of the one in Edwards et al. [2004]. We found more accurate results than Edwards et al.’s work and did not find the occluder’s main effect or its two-way interaction effect with distance on the accuracy of observers’ depth matching. The second experiment was an updated version of the first one using a within-subject design and a more accurate calibration method. The results were that errors ranged from –5 to 3 mm when the occluder was present, –3 to 2 mm when the occluder was absent, and observers judged the virtual object to be closer after the presentation of the occluder. The third experiment was conducted on three subjects who were depth perception researchers. The result showed significant individual effects.

This thesis presents an efficient buffer management scheme for 3-D graphic rendering systems. The purpose of this scheme is to reduce the off-chip memory accesses, which have become a valuable resource, and very often a performance bottleneck of embedded 3-D applications. The 3-D buffers, including depth and color frame buffers, will be divided into rectangular blocks. The proposed scheme can first provide the management of buffer clear operation. For most of time, the rendering of each 3-D frame starts from the buffer clear command to clear the data remaining in buffers from the previous frame. Instead of clearing the buffers residing in the off-chip memory immediately, our scheme will just set the clear flag in an on-chip buffer management table which provides a control information entry for each of the blocks in the buffer. When the blocks have to be accessed later during rendering process, they won¡¦t be brought in from on-chip memory; instead, they are cleared directly in the corresponding cache location. When the cache blocks are replaced, the corresponding off-chip buffer blocks will be updated. Only those blocks in the off-chip color buffer which are not visited will be actually cleared when the color frame is swapped for display. The second contribution of the propose management scheme is to compress and decompress the depth blocks to save the transfer data amount of these blocks. Since the difference of the depth values of the neighboring pixels belonging to the same triangle plane will be the same, this difference value can be stored and encoded along with the run-length information which can lead to significant saving of the storage space. The actual reduction ratio depends on the relative object complexity to the output screen size, the block size, and the degree of the anti-aliasing considered. However, our experimental results show that the compression ratio of 17-28% can be achieved for the moderate block size. The entire buffer management has been implemented, and the entire gate count is 65k, which is about 10% of the entire 3-D systems. The proposed management chip is very suitable for embedded 3D graphic rendering systems where the memory bandwidth budget is very tightly restricted.

The Dirichlet process is perhaps the most popular prior used in the nonparametric Bayesian inference. This prior which is placed on the space of probability distributions has conjugacy property and asymptotic consistency. In this thesis, our concentration is on applying this nonparametric Bayesian inference on the Tukey depth and Tukey median. Due to the complexity of the distribution of Tukey median, we use this nonparametric Bayesian inference, namely the Lo’s bootstrap, to approximate the distribution of the Tukey median. We also compare our results with the Efron’s bootstrap and Rubin’s bootstrap. Furthermore, the existing asymptotic theory for the Tukey median is reviewed. Based on these existing results, we conjecture that the bootstrap sample Tukey median converges to the same asymp- totic distribution and our simulation supports the conjecture that the asymptotic consistency holds.

Yes / Human fall detection systems play an important role in our daily life, because falls are the main obstacle for elderly people to live independently and it is also a major health concern due to aging population. Different approaches are used to develop human fall detection systems for elderly and people with special needs. The three basic approaches include some sort of wearable devices, ambient based devices or non-invasive vision-based devices using live cameras. Most of such systems are either based on wearable or ambient sensor which is very often rejected by users due to the high false alarm and difficulties in carrying them during their daily life activities. This paper proposes a fall detection system based on the height, velocity and position of the subject using depth information from Microsoft Kinect sensor. Classification of human fall from other activities of daily life is accomplished using height and velocity of the subject extracted from the depth information. Finally position of the subject is identified for fall confirmation. From the experimental results, the proposed system was able to achieve an average accuracy of 94.81% with sensitivity of 100% and specificity of 93.33%. / Partly sponsored by Center for Graduate Studies. This work is funded under the project titled “Biomechanics computational modeling using depth maps for improvement on gait analysis”. Universiti Tun Hussein Onn Malaysia for provided lab components and GPPS (Project Vot No. U462) sponsor.

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