Integrated modelling of the thermal, chemical and geomechanical processes in underground coal gasification

The considerate focus on unconventional fossil fuel resources is a natural consequence of emerging global energy requirements and the ever more limited opportunities to deploy new conventional resources. Underground Coal Gasification (UCG) is an unconventional method for recovering energy from coal resources through in-situ conversion to gas. An oxidising gas agent is injected to initiate and sustain the in-situ coal gasification. The quality of the collected product syngas is characterised by its carbon monoxide (CO), hydrogen (H2) and methane (CH4) content. However, as it is an unconventional method of energy production it evolves through research conducted through modelling studies, laboratory and in-situ trials which support this evolution process. The purpose of this PhD research project is to identify and model the critical parameters which will give increased control on the underground process and ultimately the composition of the final syngas product. In order to achieve this objective, it is necessary to breakdown the UCG process to interrelated stages and design component models that realistically simulate the chemical and physical processes that take place. In the core of the UCG lays the coal gasification process and the simultaneous cavity growth within the coal seam and these will be studied as part of this PhD research. An integrated simulation methodology, which considers the thermal, chemical and geomechanical processes has led to the development of the coupled Thermo-Mechanical-Chemical (TMC) model. Experimental and literature data is used to validate and calibrate the developed models. In addition to increased understanding of the UCG process and its control, this research allows for UCG investors to maximise the financial value sourced from the end-product gas as well as reduce the risk of making unprofitable investments. A number of geologically representative UCG scenarios are simulated through the developed TMC model. The scenarios aim at evaluating the impact of various operational parameters to the UCG operation. The coal panel thickness, the panel depth below the surface, the operating pressure, the type of the injected agent as well as the type of coal where UCG takes place are among the tested parameters. The simulation methodology is based on coupling two industry standard simulators, Advanced System for Process ENgineering (ASPEN) Plus, used for the thermo-chemical simulation, and FLAC3D, which enables the thermo-mechanical simulation of the UCG process. The coupling of the two simulation tools is achieved through sequential interchange of data and through the development of an additional transitional Gasification Support module. The Gasification Support module facilitates the exchange of data between the two simulators and focus on the participating heat and mass transport phenomena within the growing UCG cavity. Principally, the Aspen Plus model simulates the chemical processes taking place in the coal seam and focuses on the thermodynamic, mass and heat transfer modelling components in order to calculate the amount of produced heat, as well as gas under restricted Gibbs minimisation and equilibrium conditions. In addition to the different chemical reactors that constitute the Aspen Plus model constructed, calculator blocks written in Fortran code were introduced to regulate modelling performance in line with experimental data. The Aspen Plus simulation also facilitated the development of different process designs depending on the employed UCG layout (i.e. Linked Vertical Wells, Continuous Retracting Injection Point). The FLAC3D model reflects realistically the 3D spatial features of a gasified coal seam underground. This module produces the resulting thermo-mechanical stress distributions on the coal seam and the surrounding strata, taking account of both mechanical failure and coal spalling effects, heat transfer rates within the cavity and the surrounding strata. The cavity growth modelling results include the extent and the growth rate of the developing UCG cavity given the specified operational parameters such as the coal characteristics (e.g. composition, formation thickness, depth), the composition of reagents injected (i.e. air, oxygen, steam) and the feed rate, the pressure, the gasification and the combustion temperatures. In addition, the UCG product gas characteristics (e.g. composition, heating value) and the participating heat and mass transfer phenomena are also analysed in comparison with the operational parameters of the UCG process.Open Acces

EXPLORING NEURAL NETWORK DEFENSES WITH ADVERSARIAL MIXUP

Neural networks (NNs) are vulnerable to adversarial examples, and extensive research is aimed at detecting them. However, detecting adversarial examples is not easy, even with the construction of new loss functions in a network. In this study, we introduce the Adversarial Mix up (AdvMix) network, a neural network that adds a None of the Above (NOTA) class on top of the existing classes to isolate the space where adversarial examples exist. We investigate the effectiveness of AdvMix in improving the robustness of models trained on deep neural networks against adversarial attacks by detecting them. We experimented with various data augmentation techniques and trained nine different models. Our findings show that using an AdvMix network can significantly improve the performance of models against various attacks while achieving better accuracy on benign examples. We were able to increase the accuracy of the vanilla model from 91% to 95% and improve the model's robustness. In many cases, we were able to eliminate the vulnerability of models against some popular and efficient attacks.Captain, Hellenic ArmyApproved for public release. Distribution is unlimited

Rockfall hazard and risk assessment of road slopes.

Οι καταπτώσεις βράχων σε οδικές αρτηρίες, οδηγούν σε σημαντικές επιπτώσεις και συνεπώς είναι ιδιαίτερα σημαντική η εκτίμηση του επιπέδου της επικινδυνότητας σε πρανή οδοποιίας και η λήψη μέτρων προστασίας. Στην παρούσα εργασία συγκρίνονται οι σημαντικότερες μέθοδοι εκτίμησης της επικινδυνότητας και της διακινδύνευσης καταπτώσεων βράχων. Όσον αφορά την επικινδυνότητα, λαμβάνονται υπόψη παράμετροι όπως η γεωμετρία του πρανούς, οι κυκλοφοριακές συνθήκες, η γεωλογία και τα χαρακτηριστικά της βραχόμαζας, οι καιρικές συνθήκες, τα ιστορικά δεδομένα, κ.α. Εκτίμηση της επικινδυνότητας μπορεί επίσης να προκύψει μέσω δισδιάστατων ή τρισδιάστατων μοντέλων προσομοίωσης τροχιάς, όπου συνδυάζονται τα δεδομένα της συχνότητας βραχοπτώσεων με την κινητική ενέργεια του καταπίπτοντος τεμάχους βράχου. Όσον αφορά την εκτίμηση της διακινδύνευσης, έχουν αναπτυχθεί διάφορες μέθοδοι, που ποικίλουν από απλοϊκές προσεγγίσεις, έως ολοκληρωμένες πιθανολογικές ή ποσοτικές μέθοδοι. Τέλος, ως παράδειγμα, χρησιμοποιήθηκαν οι καταλληλότερες μέθοδοι εξ αυτών για την εκτίμηση της επικινδυνότητας και διακινδύνευσης από καταπτώσεις βράχων, σε δύο τυπικές διατομές της Εθνικής Οδού Αθηνών – Θεσσαλονίκης, στο τμήμα των Τεμπών, όπου έχουν καταγραφεί αρκετά συμβάντα καταπτώσεων βράχων τα τελευταία χρόνια.This paper presents and compares the main methods of hazard and risk assessment for road slopes. Hazard assessment is achieved by rating several parameters such as the slope’s geometry, traffic conditions, the geology and the rockmass properties, weather conditions, historical rockfall data etc. A hazard assessment can also be executed using 2D or 3D trajectory models, by combining the frequency of a rockfall and the kinetic energy of a falling rock. Several methodologies have been developed for risk assessment, varying from simplistic approaches to comprehensive probabilistic or quantitative risk assessment methods. Finally, the most suitable methods were used in order to assess the level of hazard and risk as an example (the data from two sections of the national road at Tempi Gorge, Greece) where many rockfall events occurred in the past few years

In Vivo Yeast Cell Morphogenesis Is Regulated by a p21-Activated Kinase in the Human Pathogen Penicillium marneffei

Pathogens have developed diverse strategies to infect their hosts and evade the host defense systems. Many pathogens reside within host phagocytic cells, thus evading much of the host immune system. For dimorphic fungal pathogens which grow in a multicellular hyphal form, a central attribute which facilitates growth inside host cells without rapid killing is the capacity to switch from the hyphal growth form to a unicellular yeast form. Blocking this transition abolishes or severely reduces pathogenicity. Host body temperature (37°C) is the most common inducer of the hyphal to yeast transition in vitro for many dimorphic fungi, and it is often assumed that this is the inducer in vivo. This work describes the identification and analysis of a new pathway involved in sensing the environment inside a host cell by a dimorphic fungal pathogen, Penicillium marneffei. The pakB gene, encoding a p21-activated kinase, defines this pathway and operates independently of known effectors in P. marneffei. Expression of pakB is upregulated in P. marneffei yeast cells isolated from macrophages but absent from in vitro cultured yeast cells produced at 37°C. Deletion of pakB leads to a failure to produce yeast cells inside macrophages but no effect in vitro at 37°C. Loss of pakB also leads to the inappropriate production of yeast cells at 25°C in vitro, and the mechanism underlying this requires the activity of the central regulator of asexual development. The data shows that this new pathway is central to eliciting the appropriate morphogenetic response by the pathogen to the host environment independently of the common temperature signal, thus clearly separating the temperature- and intracellular-dependent signaling systems

ShopSmart 4 Health - protocol of a skills-based randomised controlled trial promoting fruit and vegetable consumption among socioeconomically disadvantaged women

BackgroundThere is a need for evidence on the most effective and cost-effective approaches for promoting healthy eating among groups that do not meet dietary recommendations for good health, such as those with low incomes or experiencing socioeconomic disadvantage. This paper describes the ShopSmart 4 Health study, a randomised controlled trial conducted by Deakin University, Coles Supermarkets and the Heart Foundation, to investigate the effectiveness and cost-effectiveness of a skill-building intervention for promoting increased purchasing and consumption of fruits and vegetables amongst women of low socioeconomic position (SEP).Methods/designShopSmart 4 Health employed a randomised controlled trial design. Women aged 18&ndash;60 years, holding a Coles store loyalty card, who shopped at Coles stores within socioeconomically disadvantaged neighbourhoods and met low-income eligibility criteria were invited to participate. Consenting women completed a baseline survey assessing food shopping and eating habits and food-related behaviours and attitudes. On receipt of their completed survey, women were randomised to either a skill-building intervention or a wait-list control condition. Intervention effects will be evaluated via self-completion surveys and using supermarket transaction sales data, collected at pre- and post-intervention and 6-month follow-up. An economic evaluation from a societal perspective using a cost-consequences approach will compare the costs and outcomes between intervention and control groups. Process evaluation will be undertaken to identify perceived value and effects of intervention components.DiscussionThis study will provide data to address the currently limited evidence base regarding the effectiveness and cost-effectiveness of skill-building intervention strategies aimed at increasing fruit and vegetable consumption among socioeconomically disadvantaged women, a target group at high risk of poor diets.<br /

The Multi-faceted Implementation of Telepractice to Service Individuals with Autism

Telepractice is a method of service delivery in which professionals provide intervention, assessment and consultation services to individuals through the use of telecommunication technologies.  In response to the nationwide school-based shortage of speech-language pathologists, telepractice has emerged as a viable way to reach underserved clients. Telepractice has the potential to extend to populations in need of services, including those diagnosed with autism.  This paper examines an evidence-based clinical model for the delivery of telepractice services and describes the policies and procedures required for assessing individual need, confidentiality, technology, training and documentation within a telepractice program.  Two clinical case studies involving individuals diagnosed with autism are described and provide initial evidence for the use of telepractice as a practical method for direct and consultative service delivery. Results indicated that both the student receiving direct services, and the treating clinician receiving consultative services via telepractice, demonstrated an increased skill level in target domains

A p21-Activated Kinase Is Required for Conidial Germination in Penicillium marneffei

Asexual spores (conidia) are the infectious propagules of many pathogenic fungi, and the capacity to sense the host environment and trigger conidial germination is a key pathogenicity determinant. Germination of conidia requires the de novo establishment of a polarised growth axis and consequent germ tube extension. The molecular mechanisms that control polarisation during germination are poorly understood. In the dimorphic human pathogenic fungus Penicillium marneffei, conidia germinate to produce one of two cell types that have very different fates in response to an environmental cue. At 25 °C, conidia germinate to produce the saprophytic cell type, septate, multinucleate hyphae that have the capacity to undergo asexual development. At 37 °C, conidia germinate to produce the pathogenic cell type, arthroconidiating hyphae that liberate uninucleate yeast cells. This study shows that the p21-activated kinase pakA is an essential component of the polarity establishment machinery during conidial germination and polarised growth of yeast cells at 37 °C but is not required for germination or polarised growth at 25 °C. Analysis shows that the heterotrimeric G protein α subunit GasC and the CDC42 orthologue CflA lie upstream of PakA for germination at both temperatures, while the Ras orthologue RasA only functions at 25 °C. These findings suggest that although some proteins that regulate the establishment of polarised growth in budding yeast are conserved in filamentous fungi, the circuitry and downstream effectors are differentially regulated to give rise to distinct cell types