311 research outputs found
Sonar image interpretation for sub-sea operations
Mine Counter-Measure (MCM) missions are conducted to neutralise underwater
explosives. Automatic Target Recognition (ATR) assists operators by
increasing the speed and accuracy of data review. ATR embedded on vehicles
enables adaptive missions which increase the speed of data acquisition. This
thesis addresses three challenges; the speed of data processing, robustness of
ATR to environmental conditions and the large quantities of data required to
train an algorithm.
The main contribution of this thesis is a novel ATR algorithm. The algorithm
uses features derived from the projection of 3D boxes to produce a set of 2D
templates. The template responses are independent of grazing angle, range
and target orientation. Integer skewed integral images, are derived to accelerate
the calculation of the template responses. The algorithm is compared
to the Haar cascade algorithm. For a single model of sonar and cylindrical
targets the algorithm reduces the Probability of False Alarm (PFA) by 80%
at a Probability of Detection (PD) of 85%. The algorithm is trained on target
data from another model of sonar. The PD is only 6% lower even though no
representative target data was used for training.
The second major contribution is an adaptive ATR algorithm that uses local
sea-floor characteristics to address the problem of ATR robustness with
respect to the local environment. A dual-tree wavelet decomposition of the
sea-floor and an Markov Random Field (MRF) based graph-cut algorithm is
used to segment the terrain. A Neural Network (NN) is then trained to filter
ATR results based on the local sea-floor context. It is shown, for the Haar
Cascade algorithm, that the PFA can be reduced by 70% at a PD of 85%.
Speed of data processing is addressed using novel pre-processing techniques.
The standard three class MRF, for sonar image segmentation, is formulated
using graph-cuts. Consequently, a 1.2 million pixel image is segmented in
1.2 seconds. Additionally, local estimation of class models is introduced to
remove range dependent segmentation quality. Finally, an A* graph search
is developed to remove the surface return, a line of saturated pixels often
detected as false alarms by ATR. The A* search identifies the surface return
in 199 of 220 images tested with a runtime of 2.1 seconds. The algorithm is
robust to the presence of ripples and rocks
Review article: Review of fragility analyses for major building types in China with new implications for intensity-PGA relation development
The evaluation of the seismic fragility of buildings is one key task of earthquake safety and loss assessment. Many research reports and papers have been published over the past 4 decades that deal with the vulnerability of buildings to ground motion caused by earthquakes in China. We first scrutinized 69 papers and theses studying building damage for earthquakes that occurred in densely populated areas. They represent observations where macroseismic intensities have been determined according to the official Chinese Seismic Intensity Scale. From these many studies we derived the median fragility functions (dependent on intensity) for four damage limit states of the two most widely distributed building types: masonry and reinforced concrete.We also inspected 18 publications that provide analytical fragility functions (dependent on PGA, peak ground acceleration) for the same damage classes and building categories. Thus, a solid fragility database based on both intensity and PGA is established for seismicity-prone areas in mainland China. A comprehensive view of the problems posed by the evaluation of fragility for different building types is given. Based on the newly collected fragility database, we propose a new approach in deriving intensity–PGA relations by using fragility as the bridge, and reasonable intensity–PGA relations are developed. This novel approach may shed light on new thought in decreasing the scatter in traditional intensity–PGA relation development, i.e., by further classifying observed macroseismic intensities and instrumental ground motions based on differences in building seismic resistance capability
Losses Associated with Secondary Effects in Earthquakes
The number of earthquakes with high damage and high losses has been limited to around 100 events since 1900. Looking at historical losses from 1900 onward, we see that around 100 key earthquakes (or around 1% of damaging earthquakes) have caused around 93% of fatalities globally. What is indeed interesting about this statistic is that within these events, secondary effects have played a major role, causing around 40% of economic losses and fatalities as compared to shaking effects. Disaggregation of secondary effect economic losses and fatalities demonstrating the relative influence of historical losses from direct earthquake shaking in comparison to tsunami, fire, landslides, liquefaction, fault rupture, and other type losses is important if we are to understand the key causes post-earthquake. The trends and major event impacts of secondary effects are explored in terms of their historic impact as well as looking to improved ways to disaggregate them through two case studies of the Tohoku 2011 event for earthquake, tsunami, liquefaction, fire, and the nuclear impact; as well as the Chilean 1960 earthquake and tsunami event
A spatial correlation model of peak ground acceleration and response spectra based on data of the Istanbul Earthquake Rapid Response and Early Warning System
CEDIM Forensic Disaster Analysis Group (FDA) "Volcano & Tsunami Hunga Tonga" Report No. 1
Der Vulkanausbruch im Südpazifik (Tongainseln) Mitte Januar 2022 war der weltweit stärkste seit dem Ausbruch des Pinatubo. Hunga Tonga ist ein großer unterseeischer Vulkan etwa 70 km nordwestlich von Tongatapu (Südwestpazifik). Der Vulkan besteht aus zwei kleinen Inseln, Hunga Tonga und Hunga Ha\u27apai, die durch die jüngsten Ausbrüche in den Jahren 1988, 2009 und 2014/2015 miteinander verbunden wurden. Die Eruptionssequenz begann am 20. Dezember 2021 mit einer einzelnen Eruption. Es folgten ein größeres Ereignis am 14. Januar und der Hauptausbruch am 15. Januar gegen 17:15 Uhr Ortszeit (04:15 Uhr UTC). Alle Eruptionen waren mit einem starken Überschallknall verbunden. Die Explosion der Haupteruption war über Tausende von Kilometern zu hören.
Die Haupteruption löste eine große Massenbewegung aus, die als Quelle für den anschließenden Tsunami vermutet wird. Der Tsunami wurde innerhalb von 15 Minuten auf Tongatapu beobachtet und unterbrach die Energieversorgung. Der Tsunami wurde im gesamten Pazifik, im Korallenmeer und im Tasmanischen Meer mit einer Ausbreitung von bis zu 3 m gesichtet.
Es kam zu schweren lokalen Überschwemmungen auf Tonga (Run-up von 2 bis 5 m) und lokal zu leichten bis mäßigen Überschwemmungen entlang des Korallenmeers (< 0,5 – 3 m) und entlang des Pazifiks (0,5 – 1,5 m). Verschiedene Inseln von Tonga wurden teilweise überflutet. Die kleinen, unbewohnten Inseln Nuku und Tau wurden vollständig erodiert. Die Überschwemmungen auf Tongatapu und Nomuka zerstörten mehrere Gebäude. Korallenriffe und Barriere-Inseln spielten eine wichtige Rolle bei der Abmilderung der Auswirkungen des Tsunami.
Die größten Schäden sind auf den Bruch des Unterseekabels von Fidschi nach Tonga zurückzuführen. Die wirtschaftlichen Verluste, die mit einem solchen Ausfall verbunden sind, werden angesichts der Kosten und der Knappheit von Satellitentelefonen groß sein. Ein großes Problem stellt derzeit die Asche auf der Landebahn von Tongatapu dar, so dass Hilfsflugzeuge meist nicht landen können, um Hilfsgüter zu liefern. Zusätzliche Kosten im Zusammenhang mit den Aufräumarbeiten und der Beseitigung der Asche werden auch in der Landwirtschaft anfallen, ebenso wie mögliche Infrastrukturprobleme durch die Verunreinigung der Wasserversorgung
Surrogate Modeling-Driven Physics-Informed Multi-fidelity Kriging: Path Forward to Digital Twin Enabling Simulation for Accident Tolerant Fuel
The Gaussian Process (GP)-based surrogate model has the inherent capability
of capturing the anomaly arising from limited data, lack of data, missing data,
and data inconsistencies (noisy/erroneous data) present in the modeling and
simulation component of the digital twin framework, specifically for the
accident tolerant fuel (ATF) concepts. However, GP will not be very accurate
when we have limited high-fidelity (experimental) data. In addition, it is
challenging to apply higher dimensional functions (>20-dimensional function) to
approximate predictions with the GP. Furthermore, noisy data or data containing
erroneous observations and outliers are major challenges for advanced ATF
concepts. Also, the governing differential equation is empirical for
longer-term ATF candidates, and data availability is an issue. Physics-informed
multi-fidelity Kriging (MFK) can be useful for identifying and predicting the
required material properties. MFK is particularly useful with low-fidelity
physics (approximating physics) and limited high-fidelity data - which is the
case for ATF candidates since there is limited data availability. This chapter
explores the method and presents its application to experimental thermal
conductivity measurement data for ATF. The MFK method showed its significance
for a small number of data that could not be modeled by the conventional
Kriging method. Mathematical models constructed with this method can be easily
connected to later-stage analysis such as uncertainty quantification and
sensitivity analysis and are expected to be applied to fundamental research and
a wide range of product development fields. The overarching objective of this
chapter is to show the capability of MFK surrogates that can be embedded in a
digital twin system for ATF
Exploring the hidden shallows: extensive reef development and resilience within the turbid nearshore Great Barrier Reef
Mean coral cover on Australia's Great Barrier Reef (GBR) has reportedly declined by over 15% during the last 30 years. Climate change events and outbreaks of coral disease have been major drivers of degradation, often exacerbating the stresses caused by localised human activities (e.g. elevated sediment and nutrient inputs). Here, however, in the first assessment of nearshore reef occurrence and ecology across meaningful spatial scales (15.5 sq km), we show that areas of the GBR shelf have exhibited strong intra-regional variability in coral resilience to declining water quality. Specifically, within the highly-turbid "mesophotic" nearshore (<10 m depth) of the central GBR, where terrigenous seafloor sediments are persistently resuspended by wave processes, coral cover averages 38% (twice that reported on mid- and outer-shelf reefs). Of the mapped area, 11% of the seafloor has distinct reef or coral community cover, a density comparable to that measured across the entire GBR shelf (9%). Identified coral taxa (21 genera) exhibited clear depth-stratification corresponding closely to light attenuation and seafloor topography. Reefs have accreted relatively rapidly during the late-Holocene (1.8-3.0 mm y-1) with rates of vertical reef growth influenced by intrinsic shifts in coral assemblages associated with reef development. Indeed, these shallow-water reefs may have similar potential as refugia from large-scale disturbance as their deep-water
(>30 m) "mesophotic" equivalents, and also provide a basis from which to model future trajectories of reef growth within nearshore areas
Residential building stock modelling for mainland China targeted for seismic risk assessment
To enhance the estimation accuracy of economic loss and casualty in seismic risk assessment, a high-resolution building exposure model is necessary. Previous studies in developing global and regional building exposure models usually use coarse administrative-level (e.g. country or sub-country level) census data as model inputs, which cannot fully reflect the spatial heterogeneity of buildings in large countries like China. To develop a high-resolution residential building stock model for mainland China, this paper uses finer urbanity-level population and building-related statistics extracted from the records in the tabulation of the 2010 population census of the People\u27s Republic of China (hereafter abbreviated as the “2010 census”). In the 2010 census records, for each province, the building-related statistics are categorized into three urbanity levels (urban, township, and rural). To disaggregate these statistics into high-resolution grid level, we need to determine the urbanity attributes of grids within each province. For this purpose, the geo-coded population density profile (with 1 km × 1 km resolution) developed in the 2015 Global Human Settlement Layer (GSHL) project is selected. Then for each province, the grids are assigned with urban, township, or rural attributes according to the population density in the 2015 GHSL profile. Next, the urbanity-level building-related statistics can be disaggregated into grids, and the 2015 GHSL population in each grid is used as the disaggregation weight. Based on the four structure types (steel and reinforced concrete, mixed, brick and wood, other) and five storey classes (1, 2–3, 4–6, 7–9, ≥10) of residential buildings classified in the 2010 census records, we reclassify the residential buildings into 17 building subtypes attached with both structure type and storey class and estimate their unit construction prices. Finally, we develop a geo-coded 1 km × 1 km resolution residential building exposure model for 31 provinces of mainland China. In each 1 km × 1 km grid, the floor areas of the 17 residential building subtypes and their replacement values are estimated. The model performance is evaluated to be satisfactory, and its practicability in seismic risk assessment is also confirmed. Limitations of the proposed model and directions for future improvement are discussed. The whole modelling process presented in this paper is fully reproducible, and all the modelled results are publicly accessible
Oral Delivery of Bioencapsulated Exendin-4 Expressed in Chloroplasts Lowers Blood Glucose Level in Mice and Stimulates Insulin Secretion in Beta-TC6 Cells
Glucagon like peptide (GLP-1) increases insulin secretion but is rapidly degraded (half-life: 2 min in circulation). GLP-1 analog, Exenatide (Byetta) has a longer half life (3.3–4 hrs) with potent insulinotropic effects but requires cold storage, daily abdominal injections with short shelf life. Because diabetic patients take \u3e60,000 injections in their life time, alternative delivery methods are highly desired. Exenatide is ideal for oral delivery because insulinotropism is glucose dependent, with reduced risk of hypoglycemia even at higher doses. Therefore, exendin-4 (EX4) was expressed as a cholera toxin B subunit (CTB)-fusion protein in tobacco chloroplasts to facilitate bioencapsulation within plant cells and transmucosal delivery in the gut via GM1 receptors present in the intestinal epithelium. The transgene integration was confirmed by PCR and Southern blot analysis. Expression level of CTB-EX4 reached up to 14.3% of total leaf protein (TLP). Lyophilization of leaf material increased therapeutic protein concentration by 12–24 fold, extended their shelf life up to 15 months when stored at room temperature and eliminated microbes present in fresh leaves. The pentameric structure, disulfide bonds and functionality of CTB-EX4 were well preserved in lyophilized materials. Chloroplast derived CTB-EX4 showed increased insulin secretion similar to the commercial EX4 in beta-TC6, a mouse pancreatic cell line. Even when 5,000-fold excess dose of CTB-EX4 was orally delivered, it stimulated insulin secretion similar to the intraperitoneal injection of commercial EX4 but didn’t cause hypoglycemia in mice. Oral delivery of the bioencapsulated EX4 should eliminate injections, increase patient compliance/convenience and significantly lower their cost
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