10,404 research outputs found

    Radiotherapy dosimetry with ultrasound contrast agents

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    Proceedings of the 10th International congress on architectural technology (ICAT 2024): architectural technology transformation.

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    The profession of architectural technology is influential in the transformation of the built environment regionally, nationally, and internationally. The congress provides a platform for industry, educators, researchers, and the next generation of built environment students and professionals to showcase where their influence is transforming the built environment through novel ideas, businesses, leadership, innovation, digital transformation, research and development, and sustainable forward-thinking technological and construction assembly design

    Flow characterization of compressible particulate biomass materials

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    Biomass materials like trees and crops can be converted to biochemical products and have been considered as one of the most promising alternatives for energy and fuels due to their abundance and easy access. However, the commercialization of bioenergy has been significantly constrained by severe issues during the handling of particulate biomass materials, manifested as unstable flow and jamming in handling equipment such as hoppers, feeders, or conveyors. Solving these issues centers on the mechanistic understanding of the flowability of milled biomass materials and their rheological and constitutive behaviors in various industrial equipment. This thesis investigates the flow behavior of milled woody biomass across multiple scales and flow regimes. The study experimentally quantifies the mechanical and rheological properties of particulate biomass at particle, meso, and industrial scales, complemented by FEM simulations of biomass flow through hoppers and inclined planes at meso and industrial scales. The jamming physics of woody particles in wedge-shaped hoppers is analyzed in consideration of hopper geometry, particle density, packing, and surcharge. With these results, parameters governing the arching, mass flow, and funnel flow of milled biomass through industry hoppers are identified. These findings enable the design and optimization of industry hoppers for the efficient handling of milled woody biomass. In addition, the constitutive model characterizing the flow of milled woody biomass at both quasi-static and dynamic flow regimes is formulated and validated against laboratory data. In the end, the impacts of moisture content on the mechanical and flow behavior of milled woody biomass are evaluated. This study promotes the fundamental understanding of the flow physics of milled biomass materials across various scales, fosters high-fidelity numerical prediction models of the constitutive responses of compressible particulate biomass, and enables the development of the next-generation high-efficiency biomass handling equipment to reduce the cost and increase the safety of feedstock processing.Ph.D

    Enhancing the forensic comparison process of common trace materials through the development of practical and systematic methods

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    An ongoing advancement in forensic trace evidence has driven the development of new and objective methods for comparing various materials. While many standard guides have been published for use in trace laboratories, different areas require a more comprehensive understanding of error rates and an urgent need for harmonizing methods of examination and interpretation. Two critical areas are the forensic examination of physical fits and the comparison of spectral data, which depend highly on the examiner’s judgment. The long-term goal of this study is to advance and modernize the comparative process of physical fit examinations and spectral interpretation. This goal is fulfilled through several avenues: 1) improvement of quantitative-based methods for various trace materials, 2) scrutiny of the methods through interlaboratory exercises, and 3) addressing fundamental aspects of the discipline using large experimental datasets, computational algorithms, and statistical analysis. A substantial new body of knowledge has been established by analyzing population sets of nearly 4,000 items representative of casework evidence. First, this research identifies material-specific relevant features for duct tapes and automotive polymers. Then, this study develops reporting templates to facilitate thorough and systematic documentation of an analyst’s decision-making process and minimize risks of bias. It also establishes criteria for utilizing a quantitative edge similarity score (ESS) for tapes and automotive polymers that yield relatively high accuracy (85% to 100%) and, notably, no false positives. Finally, the practicality and performance of the ESS method for duct tape physical fits are evaluated by forensic practitioners through two interlaboratory exercises. Across these studies, accuracy using the ESS method ranges between 95-99%, and again no false positives are reported. The practitioners’ feedback demonstrates the method’s potential to assist in training and improve peer verifications. This research also develops and trains computational algorithms to support analysts making decisions on sample comparisons. The automated algorithms in this research show the potential to provide objective and probabilistic support for determining a physical fit and demonstrate comparative accuracy to the analyst. Furthermore, additional models are developed to extract feature edge information from the systematic comparison templates of tapes and textiles to provide insight into the relative importance of each comparison feature. A decision tree model is developed to assist physical fit examinations of duct tapes and textiles and demonstrates comparative performance to the trained analysts. The computational tools also evaluate the suitability of partial sample comparisons that simulate situations where portions of the item are lost or damaged. Finally, an objective approach to interpreting complex spectral data is presented. A comparison metric consisting of spectral angle contrast ratios (SCAR) is used as a model to assess more than 94 different-source and 20 same-source electrical tape backings. The SCAR metric results in a discrimination power of 96% and demonstrates the capacity to capture information on the variability between different-source samples and the variability within same-source samples. Application of the random-forest model allows for the automatic detection of primary differences between samples. The developed threshold could assist analysts with making decisions on the spectral comparison of chemically similar samples. This research provides the forensic science community with novel approaches to comparing materials commonly seen in forensic laboratories. The outcomes of this study are anticipated to offer forensic practitioners new and accessible tools for incorporation into current workflows to facilitate systematic and objective analysis and interpretation of forensic materials and support analysts’ opinions

    Experimental and Theoretical Studies of Unstable Dynamics of Caltech’s Plasma Jet: X-Rays, Ultraviolet, and Visible Light

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    The Caltech plasma jet experiment launches a laboratory plasma jet that is analogous to an astrophysical jet. Even though the temperature of the plasma jet is around 2 eV, 6 keV X-rays and 20--60 eV extreme ultraviolet (EUV) radiation were detected when the plasma jet was perturbed by magnetohydrodynamic instabilities. How charged particles in a plasma are accelerated to suprathermal energy has been a key question in plasma physics, solar physics, and astrophysics. Studying these surprisingly energetic radiations from Caltech’s plasma jet can help answer this question. Toward this goal, this thesis contains an experimental study of the X-rays and a theoretical study of the EUV radiation. In the experimental study, a PIN-diode-based 1D X-ray camera has been developed to spatially, temporally, and spectrally resolve the transient, low-intensity, and suprathermal X-rays detected to be simultaneous with magnetohydrodynamic instabilities that disrupt the plasma jet. This X-ray camera has high detection efficiency over the 5–10 keV X-ray band, an over 20-degree field of view (FOV), and the capability to produce more than 50 time-resolved frames with a submicrosecond time resolution. The X-ray images are formed by a pinhole or by a coded aperture placed outside the vacuum chamber in which the plasma jet is launched. The 1D imaging shows that the location of the X-ray source is either a few centimeters away from an inner disk electrode or near a spatially translatable metal frame that is 30–40 cm away from the electrode. In the theoretical study, we propose a collisional two-fluid model which involves a novel two-stream instability that is indifferent to collisions, even though collisions have been traditionally presumed to damp the two-stream instability. This model is used to explain previously observed localized dimming of visible light and a simultaneous, localized burst of EUV radiation from a plasma jet the cross section of which is constricted by a kink-instigated Rayleigh-Taylor instability. On being triggered by the constriction of the plasma cross section, the proposed two-stream instability produces a region of low density where an electric double layer leads to localized electron heating. The low-density region is consistent with and so likely explains the visible light dimming, and the localized electron heating is consistent with and likely explains the EUV radiation. The numerical solution of the collisional two-fluid model demonstrates good agreement with the apparent electron velocity and density profiles in the plasma jet.</p

    Beam scanning by liquid-crystal biasing in a modified SIW structure

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    A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

    A view of colonial life in South Australia: An osteological investigation of the health status among 19th-century migrant settlers

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    Studies of human skeletal remains contribute to understanding the extent to which conditions prevailing in various past communities were detrimental to health. Few of these studies have evaluated the situation in which the first European colonists of South Australia lived. Colonial Australian skeletal collections are scarce, especially for research purposes. This makes the 19th-century skeletal remains of individuals, excavated from St Mary’s Cemetery, South Australia, a rare and valuable collection. The overarching aim of this thesis was to investigate the general and oral health of this specific group of 19th-century settlers, through the examination of their skeletons and dentitions. Four research papers in this thesis address this overarching aim. The first two papers determine the general skeletal health of the settlers, with a focus on pathological manifestations on bones associated with metabolic deficiencies and the demands of establishing an industrial society. Paper 3 investigated whether Large Volume Micro- Computed Tomography (LV Micro-CT) could be used as a single technique for the analysis of the in situ dentoalveolar complex of individuals from St Mary’s. This led to a detailed investigation of the dentitions of the St Mary’s sample, in paper 4, with the aims of determining the oral health status of these individuals, and understanding how oral conditions may have influenced their general health. The skeletal remains of 65 individuals (20 adults and 45 subadults) from St Mary’s sample were available for the four component investigations using non-destructive techniques - macroscopic, radiographic and micro-CT methods. Signs of nutritional deficiencies (vitamin C and iron) were identified in Paper 1. The findings of paper 2 showed joint diseases and traumatic fractures were seen and that gastrointestinal and pulmonary conditions were the leading causes of death in subadults and adults respectively. Paper 3 found that the LV Micro-CT technique was the only method able to generate images that allowed the full range of detailed measurements across all the oral health categories studied. A combination of macroscopic and radiographic techniques covered a number of these categories, but was more time-consuming, and did not provide the same level of accuracy or include all measurements. Results for paper 4 confirmed that extensive carious lesions, antemortem tooth loss and evidence of periodontal disease were present in the St Mary’s sample. Developmental defects of enamel (EH) and areas of interglobular dentine (IGD) were identified. Many individuals with dental defects also had skeletal signs of co-morbidities. St Mary’s individuals had a similar percentage of carious lesions as the British sample, which was more than other historic Australian samples, but less than a contemporary New Zealand sample. The 19th-century migrants to the colony of South Australia were faced with multiple challenges such as adapting to local environmental conditions as well as participating in the development of settlements, infrastructure and new industries. Evidence of joint diseases, traumatic injuries and health insults, seen as pathological changes and/ or abnormalities on the bone and/or teeth, confirmed that the settlers' health had been affected. The number of burials in the ‘free ground’ area between the 1840s -1870s was greater than the number in the leased plots, reflecting the economic problems of the colony during these early years. Validation of the reliability and accuracy of the LV Micro-CT system for the analysis of the dentoalveolar complex, in situ within archaeological human skull samples, provided a microanalytical approach for the in-depth investigations of the St Mary’s dentition. Extensive carious lesions, antemortem tooth loss and periodontal disease seen in this group would have affected their general health status. The presence of developmental defects (EH and IGD) indicated that many of the settlers had suffered health insults in childhood to young adulthood. Contemporaneous Australian, New Zealand and British samples had comparable findings suggesting that little improvement had occurred in their oral health since arriving in South Australia. In conclusion, the findings of this investigation largely fulfilled the initial aims. Our understanding of the extent to which conditions prevailing in the new colony were detrimental to human health has increased, as has our knowledge of why pathological manifestations and/or abnormalities were seen on the bones and teeth of individuals from the St Mary’s sample. A multiple-method approach, to derive enhanced information has been shown to be effective, whilst establishing a new methodology (LV Micro-CT) for the analysis of dentition in situ in human archaeological skulls. Further, this investigation has digitally preserved data relating to this historical group of individuals for future comparisons.Thesis (Ph.D.) -- University of Adelaide, School of Biomedicine, 202

    Seamless Multimodal Biometrics for Continuous Personalised Wellbeing Monitoring

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    Artificially intelligent perception is increasingly present in the lives of every one of us. Vehicles are no exception, (...) In the near future, pattern recognition will have an even stronger role in vehicles, as self-driving cars will require automated ways to understand what is happening around (and within) them and act accordingly. (...) This doctoral work focused on advancing in-vehicle sensing through the research of novel computer vision and pattern recognition methodologies for both biometrics and wellbeing monitoring. The main focus has been on electrocardiogram (ECG) biometrics, a trait well-known for its potential for seamless driver monitoring. Major efforts were devoted to achieving improved performance in identification and identity verification in off-the-person scenarios, well-known for increased noise and variability. Here, end-to-end deep learning ECG biometric solutions were proposed and important topics were addressed such as cross-database and long-term performance, waveform relevance through explainability, and interlead conversion. Face biometrics, a natural complement to the ECG in seamless unconstrained scenarios, was also studied in this work. The open challenges of masked face recognition and interpretability in biometrics were tackled in an effort to evolve towards algorithms that are more transparent, trustworthy, and robust to significant occlusions. Within the topic of wellbeing monitoring, improved solutions to multimodal emotion recognition in groups of people and activity/violence recognition in in-vehicle scenarios were proposed. At last, we also proposed a novel way to learn template security within end-to-end models, dismissing additional separate encryption processes, and a self-supervised learning approach tailored to sequential data, in order to ensure data security and optimal performance. (...)Comment: Doctoral thesis presented and approved on the 21st of December 2022 to the University of Port

    Synthetic Aperture Radar (SAR) Meets Deep Learning

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    This reprint focuses on the application of the combination of synthetic aperture radars and depth learning technology. It aims to further promote the development of SAR image intelligent interpretation technology. A synthetic aperture radar (SAR) is an important active microwave imaging sensor, whose all-day and all-weather working capacity give it an important place in the remote sensing community. Since the United States launched the first SAR satellite, SAR has received much attention in the remote sensing community, e.g., in geological exploration, topographic mapping, disaster forecast, and traffic monitoring. It is valuable and meaningful, therefore, to study SAR-based remote sensing applications. In recent years, deep learning represented by convolution neural networks has promoted significant progress in the computer vision community, e.g., in face recognition, the driverless field and Internet of things (IoT). Deep learning can enable computational models with multiple processing layers to learn data representations with multiple-level abstractions. This can greatly improve the performance of various applications. This reprint provides a platform for researchers to handle the above significant challenges and present their innovative and cutting-edge research results when applying deep learning to SAR in various manuscript types, e.g., articles, letters, reviews and technical reports

    Tradition and Innovation in Construction Project Management

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    This book is a reprint of the Special Issue 'Tradition and Innovation in Construction Project Management' that was published in the journal Buildings
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