A high voltage power converter with a frequency and voltage controller

A high voltage power converter is presented in this paper and is based on a Capacitor-Diode Voltage Multiplier (CDVM) supplied through an inverter. This power converter has the capabilities of generating variable high DC voltage with improved transient response. The simulation results which are presented in this paper verify that due to its fast transient response, this converter can be used as a high DC voltage source in many applications.

A bidirectional two-leg resonant converter for high voltage pulsed power application

A high voltage pulsed power supply is proposed in this paper based on oscillation between an inductor and a capacitor in an LC circuit. A two-leg resonant circuit, supplied through an inverter with an alternative voltage waveform, can generate output voltage up to four times an input voltage magnitude. Bipolar and unipolar modulations are used in a single phase inverter to analyse their effects on the proposed resonant converter. Simulations have been carried out to evaluate the proposed topology and control.

A novel high voltage pulsed power supply based on low voltage switch-capacitor units

This paper presents a high voltage pulsed power system based on low voltage switch-capacitor units connected to a current source for several applications such as plasma systems. A buck-boost converter topology is used to utilize the current source and a series of low voltage switch-capacitor units is connected to the current source in order to provide high voltage with high voltage stress (dv/dt) as demanded by loads. This pulsed power converter is flexible in terms of energy control, in that the stored energy in the current source can be adjusted by changing the current magnitude to significantly improve the efficiency of various systems with different requirements. Output voltage magnitude and stress (dv/dt) can be controlled by a proper selection of components and control algorithm to turn on and off switching devices.

Automated road pavement marking detection from high resolution aerial images based on Multi-resolution image analysis and anisotropic Gaussian filtering

Road features extraction from remote sensed imagery has been a long-term topic of great interest within the photogrammetry and remote sensing communities for over three decades. The majority of the early work only focused on linear feature detection approaches, with restrictive assumption on image resolution and road appearance. The widely available of high resolution digital aerial images makes it possible to extract sub-road features, e.g. road pavement markings. In this paper, we will focus on the automatic extraction of road lane markings, which are required by various lane-based vehicle applications, such as, autonomous vehicle navigation, and lane departure warning. The proposed approach consists of three phases: i) road centerline extraction from low resolution image, ii) road surface detection in the original image, and iii) pavement marking extraction on the generated road surface. The proposed method was tested on the aerial imagery dataset of the Bruce Highway, Queensland, and the results demonstrate the efficiency of our approach.

Road network extraction with new vectorization and pruning from high-resolution RS images

With the increasing resolution of remote sensing images, road network can be displayed as continuous and homogeneity regions with a certain width rather than traditional thin lines. Therefore, road network extraction from large scale images refers to reliable road surface detection instead of road line extraction. In this paper, a novel automatic road network detection approach based on the combination of homogram segmentation and mathematical morphology is proposed, which includes three main steps: (i) the image is classified based on homogram segmentation to roughly identify the road network regions; (ii) the morphological opening and closing is employed to fill tiny holes and filter out small road branches; and (iii) the extracted road surface is further thinned by a thinning approach, pruned by a proposed method and finally simplified with Douglas-Peucker algorithm. Lastly, the results from some QuickBird images and aerial photos demonstrate the correctness and efficiency of the proposed process.

Variation of the Stiles-Crawford effect with accommodation and myopia

Background: Mechanical forces either due to accommodation or myopia may stretch the retina and/or cause shear between the retina and choroid. This can be investigated by making use of the Stiles-Crawford effect (SCE), which is the phenomenon of light changing in apparent brightness as it enters through different positions in the pupil. The SCE can be measured by psychophysical and objective techniques, with the SCE parameters being directionality (rate of change across the pupil), and orientation (the location of peak sensitivity in the pupil). Aims: 1. To study the changes in foveal SCE with accommodation in emmetropes and myopes using a subjective (psychophysical) technique. 2. To develop and evaluate a quick objective technique of measuring the SCE using the multifocal electroretinogram. Methods: The SCE was measured in 6 young emmetropes and 6 young myopes for up to 8 D accommodation stimulus with a psychophysical technique and its variants. An objective technique using the multifocal electroretinogram was developed and evaluated with 5 emmetropes. Results: Using the psychophysical technique, the SCE directionality increased by similar amounts in both emmetropes and myopes as accommodation increased, with an increase of 15-20% with 6 D of accommodation. However, there were no significant orientation changes. Additional measurements showed that most of the change in the directionality was probably an artefact of optical factors such as higher-order aberrations and accommodative lag rather a true effect of accommodation. The multifocal technique demonstrated the presence of the SCE, but results were noisy and too variable to detect any changes in SCE directionality or orientation with accommodation. Conclusion: There is little true change in the SCE with accommodation responses up to 6 D in either emmetropes or myopes, although it is possible that substantial changes might occur at very high accommodation levels. The objective technique using the multifocal electroretinogram was quicker and less demanding for the subjects than the psychophysical technique, but as implemented in this thesis, it is not a reliable method of measuring the SCE.

Extraction of road lanes from high-resolution stereo aerial imagery based on maximum likelihood segmentation and texture enhancement

Accurate road lane information is crucial for advanced vehicle navigation and safety applications. With the increasing of very high resolution (VHR) imagery of astonishing quality provided by digital airborne sources, it will greatly facilitate the data acquisition and also significantly reduce the cost of data collection and updates if the road details can be automatically extracted from the aerial images. In this paper, we proposed an effective approach to detect road lanes from aerial images with employment of the image analysis procedures. This algorithm starts with constructing the (Digital Surface Model) DSM and true orthophotos from the stereo images. Next, a maximum likelihood clustering algorithm is used to separate road from other ground objects. After the detection of road surface, the road traffic and lane lines are further detected using texture enhancement and morphological operations. Finally, the generated road network is evaluated to test the performance of the proposed approach, in which the datasets provided by Queensland department of Main Roads are used. The experiment result proves the effectiveness of our approach.

Campylobacter jejuni and campylobacter coli genotyping by high-resolution melting analysis of a flaA fragment

The highly variable flagellin-encoding flaA gene has long been used for genotyping Campylobacter jejuni and Campylobacter coli. High-resolution melting (HRM) analysis is emerging as an efficient and robust method for discriminating DNA sequence variants. The objective of this study was to apply HRM analysis to flaA-based genotyping. The initial aim was to identify a suitable flaA fragment. It was found that the PCR primers commonly used to amplify the flaA short variable repeat (SVR) yielded a mixed PCR product unsuitable for HRM analysis. However, a PCR primer set composed of the upstream primer used to amplify the fragment used for flaA restriction fragment length polymorphism (RFLP) analysis and the downstream primer used for flaA SVR amplification generated a very pure PCR product, and this primer set was used for the remainder of the study. Eighty-seven C. jejuni and 15 C. coli isolates were analyzed by flaA HRM and also partial flaA sequencing. There were 47 flaA sequence variants, and all were resolved by HRM analysis. The isolates used had previously also been genotyped using single-nucleotide polymorphisms (SNPs), binary markers, CRISPR HRM, and flaA RFLP. flaAHRManalysis provided resolving power multiplicative to the SNPs, binary markers, and CRISPR HRM and largely concordant with the flaA RFLP. It was concluded that HRM analysis is a promising approach to genotyping based on highly variable genes.

Can venous occlusion plethysmography be used to measure high rates of arterial inflow?

To investigate whether venous occlusion plethysmography (VOP) may be used to measure high rates of arterial inflow associated with exercise, venous occlusions were performed at rest, and following dynamic handgrip exercise at 15, 30, 45, and 60 % of maximum voluntary contraction (MVC) in seven healthy males. The effect of including more than one cardiac cycle in the calculation of blood flow was assessed by comparing the cumulative blood flow over one, two, three, or four cardiac cycles. The inclusion of more than one cardiac cycle at 30 and 60 % MVC, and more than two cardiac cycles at 15 and 45 % MVC resulted in a lower blood flow compared to using only the first cardiac cycle (P < 0.05). Despite the small time interval over which arterial inflow was measured (~1 second), this did not affect the reproducibility of the technique. Reproducibility (coefficient of variation for arterial inflow over three trials) tended to be poorer at the higher workloads, although this was not significant (12.7 ± 6.6 %, 16.2 ± 7.3 %, and 22.9 ± 9.9 % for the 15, 30, and 45 % MVC workloads; P=0.102). There was also a tendency for greater reproducibility with the inclusion of more cardiac cycles at the highest workload, but this did not reach significance (P=0.070). In conclusion, when calculated over the first cardiac cycle only during venous occlusion, high rates of FBF can be measured using VOP, and this can be achieved without a significant decrease in the reproducibility of the measurement.

The Creative Workforce : How to Launch Young People into High-Flying Futures

Creativity has become the economic engine of the 21st century. No longer the preserve of creative industries, 'creative capital' – in the form of novel thinking, navigation, interactivity and border-crossing – has become crucial to success and productivity. But are young people being equipped for a work future in which creativity is the defining feature of economic life? In this important book, Erica McWilliam argues that young people’s creative capacities are not being properly developed and that education, particularly in Australia, demands a massive pedagogical shift. Using both Australian and overseas examples, McWilliam describes what creative capacities are, why they've become important to our work futures, and what can be done to optimise the creative capacities of young people.

High fashion

High Fashion is a practice-led research enquiry that examines the processes involved in producing a no-budget film of high aesthetic standards that can confidently compete in the global film festival market, and to reflect on the production techniques tested during the making of the film. The practical outcome of the research is a twenty-five minute short drama. It incorporates a large cast and crew, original designer clothing, extravagant sets, and a popular soundtrack. The thesis considers how over one hundred professionals volunteered their time, expertise, and equipment to help produce the film. The thesis also examines the many obstacles encountered while producing the film and how these were overcome. It is written for the student filmmaker as a guide to "learn by doing."

Experimental tests on structural members fabricated from high strength steel materials

Typical high strength steels (HSS) have exceptional high strengths with improved weldability making the material attractive in modern steel constructions. However, due to lack of understanding, most of the current steel design standards are limited to conventional low strength steels (LSS, i.e. fy ≤ 450 MPa). This paper presents the details of full-scale experimental tests on short beams fabricated from BISPLATE80 HSS materials (nominal fy = 690 MPa). The various slenderness ratios of the plate elements in the test specimens were chosen in the range near the current yield limit (AS4100-1998, etc.). The experimental studies presented in this paper have produced a better understanding of the structural behaviour of HSS members subjected to local instabilities. Comparisons have also presented in the paper regarding to the design predictions from the current steel standards (AS4100-1998). This study has enabled to provide a series of proposals for proper assessment of plate slenderness limits for structural members made of representative HSS materials. This research work also enables the inclusion of further versions in the steel design specifications for typical HSS materials to be used in buildings and bridges. This paper also presents a distribution model of residual stresses in the longitudinal direction for typical HSS I-sections.

The mechanical response of the ovine lumbar anulus fibrosus to uniaxial, biaxial and shear loads

Analytical and computational models of the intervertebral disc (IVD) are commonly employed to enhance understanding of the biomechanics of the human spine and spinal motion segments. The accuracy of these models in predicting physiological behaviour of the spine is intrinsically reliant on the accuracy of the material constitutive representations employed to represent the spinal tissues. There is a paucity of detailed mechanical data describing the material response of the reinforced­ground matrix in the anulus fibrosus of the IVD. In the present study, the ‘reinforced­ground matrix’ was defined as the matrix with the collagen fibres embedded but not actively bearing axial load, thus incorporating the contribution of the fibre-fibre and fibre-matrix interactions. To determine mechanical parameters for the anulus ground matrix, mechanical tests were carried out on specimens of ovine anulus, under unconfined uniaxial compression, simple shear and biaxial compression. Test specimens of ovine anulus fibrosus were obtained with an adjacent layer of vertebral bone/cartilage on the superior and inferior specimen surface. Specimen geometry was such that there were no continuous collagen fibres coupling the two endplates. Samples were subdivided according to disc region - anterior, lateral and posterior - to determine the regional inhomogeneity in the anulus mechanical response. Specimens were loaded at a strain rate sufficient to avoid fluid outflow from the tissue and typical stress-strain responses under the initial load application and under repeated loading were determined for each of the three loading types. The response of the anulus tissue to the initial and repeated load cycles was significantly different for all load types, except biaxial compression in the anterior anulus. Since the maximum applied strain exceeded the damage strain for the tissue, experimental results for repeated loading reflected the mechanical ability of the tissue to carry load, subsequent to the initiation of damage. To our knowledge, this is the first study to provide experimental data describing the response of the ‘reinforced­ground matrix’ to biaxial compression. Additionally, it is novel in defining a study objective to determine the regionally inhomogeneous response of the ‘reinforced­ground matrix’ under an extensive range of loading conditions suitable for mechanical characterisation of the tissue. The results presented facilitate the development of more detailed and comprehensive constitutive descriptions for the large strain nonlinear elastic or hyperelastic response of the anulus ground matrix.

Combined marrow stromal cell-sheet techniques and high-strength biodegradable composite scaffolds for engineered functional bone grafts

In this study, cell sheets comprising multilayered porcine bone marrow stromal cells (BMSC) were assembled with fully interconnected scaffolds made from medical-grade polycaprolactone–calcium phosphate (mPCL–CaP), for the engineering of structural and functional bone grafts. The BMSC sheets were harvested from culture flasks and wrapped around pre-seeded composite scaffolds. The layered cell sheets integrated well with the scaffold/cell construct and remained viable, with mineralized nodules visible both inside and outside the scaffold for up to 8 weeks culture. Cells within the constructs underwent classical in vitro osteogenic differentiation with the associated elevation of alkaline phosphatase activity and bone-related protein expression. In vivo, two sets of cell-sheet-scaffold/cell constructs were transplanted under the skin of nude rats. The first set of constructs (554mm3) were assembled with BMSC sheets and cultured for 8 weeks before implantation. The second set of constructs (10104mm3) was implanted immediately after assembly with BMSC sheets, with no further in vitro culture. For both groups, neo cortical and well-vascularised cancellous bone were formed within the constructs with up to 40% bone volume. Histological and immunohistochemical examination revealed that neo bone tissue formed from the pool of seeded BMSC and the bone formation followed predominantly an endochondral pathway, with woven bone matrix subsequently maturing into fully mineralized compact bone; exhibiting the histological markers of native bone. These findings demonstrate that large bone tissues similar to native bone can be regenerated utilizing BMSC sheet techniques in conjunction with composite scaffolds whose structures are optimized from a mechanical, nutrient transport and vascularization perspective.