86 resultados para Coulomb explosion
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The geometry of ductile strain localization phenomena is related to the rheology of the deformed rocks. Both qualitative and quantitative rheological properties of natural rocks have been estimated from finite field structures such as folds and shear zones. We apply physical modelling to investigate the relationship between rheology and the temporal evolution of the width and transversal strain distribution in shear zones, both of which have been used previously as rheological proxies. Geologically relevant materials with well-characterized rheological properties (Newtonian, strain hardening, strain softening, Mohr-Coulomb) are deformed in a shear box and observed with Particle Imaging Velocimetry (PIV). It is shown that the width and strain distribution histories in model shear zones display characteristic finite responses related to material properties as predicted by previous studies. Application of the results to natural shear zones in the field is discussed. An investigation of the impact of 3D boundary conditions in the experiments demonstrates that quantitative methods for estimating rheology from finite natural structures must take these into account carefully.
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Substantial research efforts have been expended to deal with the complexity of concurrent systems that is inherent to their analysis, e.g., works that tackle the well-known state space explosion problem. Approaches differ in the classes of properties that they are able to suitably check and this is largely a result of the way they balance the trade-off between analysis time and space employed to describe a concurrent system. One interesting class of properties is concerned with behavioral characteristics. These properties are conveniently expressed in terms of computations, or runs, in concurrent systems. This article introduces the theory of untanglings that exploits a particular representation of a collection of runs in a concurrent system. It is shown that a representative untangling of a bounded concurrent system can be constructed that captures all and only the behavior of the system. Representative untanglings strike a unique balance between time and space, yet provide a single model for the convenient extraction of various behavioral properties. Performance measurements in terms of construction time and size of representative untanglings with respect to the original specifications of concurrent systems, conducted on a collection of models from practice, confirm the scalability of the approach. Finally, this article demonstrates practical benefits of using representative untanglings when checking various behavioral properties of concurrent systems.
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With the explosion of Web 2.0 application such as blogs, social and professional networks, and various other types of social media, the rich online information and various new sources of knowledge flood users and hence pose a great challenge in terms of information overload. It is critical to use intelligent agent software systems to assist users in finding the right information from an abundance of Web data. Recommender systems can help users deal with information overload problem efficiently by suggesting items (e.g., information and products) that match users’ personal interests. The recommender technology has been successfully employed in many applications such as recommending films, music, books, etc. The purpose of this report is to give an overview of existing technologies for building personalized recommender systems in social networking environment, to propose a research direction for addressing user profiling and cold start problems by exploiting user-generated content newly available in Web 2.0.
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Partington notes that clothing produced by individual consumers through adaptation of patterns is contextualised as a watered down version of original couture. In its most reductive form, this notion characterises fashion as commercial and exploitative. Descriptors such as appropriation, imitation, copy and so forth have restricted the opportunity to understand fashion as a major global cultural form and institution. Therefore exploring and understanding the concept of adaptation will shift the attention from a superficial assessment of original versus imitation or copy to adaptation as a practice that provides a better framework for the understanding of designers’ and couturiers’ innovative practices and creativity, describing also the active engagement of consumers with fashion at the micro level. Adaptation can also provide a way to understand different historical shifts in the fashion system, from individual creative agency with home dressmaking and re-making to the explosion of the mass market and the consequent abandonment of such practices. Home dressmaking has been replaced by fashion remix of mass produced garments, a practice that thrives in our environment of globalised fast fashion. Thus this chapter suggests the need for a contextual requalification of concepts such as original, copy, imitation and copyright, and argues that these categories have been played against each other, but they are in fact interdependent. Today, big labels and conglomerates try to control knowledge and innovation through copyright, but, fashion escapes copyright because, in fashion, creativity is contextual. The institutionalisation of couture from 1868 served as a way to control knowledge about production processes in fashion; on the other hand, adaptation practices, often subversive, have been fundamental to the democratisation of fashion.
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Resilient Maroochydore 2029 This exhibition showcases the work of 4th year undergraduate Landscape Architecture students in response to issues of sustainability in Maroochydore on the Queensland Sunshine coast. The projects comprising this exhibition all investigate possible design futures for the Maroochydore Centre, in the light of a series of new disturbance scenarios. Specific disturbances upon the landscape have been imagined, and design resolutions developed based on resilience to these disturbances. The proposals investigate how the Maroochydore Centre might respond to these scenarios, and how future components of the Centre might be designed for greater ‘resilience’. The Exhibition Five groups of students (32 in total) produced five strategic planning and design options toward this future: Team Transect: “What happens to a region following a sustained period of economic prosperity, with affordable property and negligible unemployment? This proposal investigates the effects on a community of massive population explosion, land shortages and inadequate planning regulations following an extended boom period.” The Foodfighters: “This proposal considers the scenario of massive food shortages and of escalating prices, and the possibility of government intervention to stabilise food supply. Strategies based upon simplified, collaborative approaches to food production are investigated.” The TTMKG: “This proposal explores the scenario of Peak Oil and the subsequent effects on society of homelessness, large scale unemployment, food shortages and global financial and political instability. Individual opportunities are restricted by the limitations of bicycle transportation.” Team Peak: “Peak Oil has restricted private vehicle transport to only the most wealthy, while public transport systems are under immense pressure. Rising unemployment drives localised trade initiatives, and the global import/export market has collapsed. This proposal considers the transition of a community from its position in a global economy to that of a relocalised economy, where basic needs are secured as close to home as possible.” After the City: “A rapid population decline as a result of the region’s failing economy has resulted in a fragmented urban fabric. This proposal investigates the possibility of new suburbanisation, reinterpretation and reinvention of space through phased processes.”
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This paper treats the blast response of a pile foundation in saturated sand using explicit nonlinear finite element analysis, considering complex material behavior of soil and soil–pile interaction. Blast wave propagation in the soil is studied and the horizontal deformation of pile and effective stresses in the pile are presented. Results indicate that the upper part of the pile to be vulnerable and the pile response decays with distance from the explosive. The findings of this research provide valuable information on the effects of underground explosions on pile foundation and will guide future development, validation and application of computer models.
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Due to increased number of terrorist attacks in recent years, loads induced by explosions need to be incorporated in building designs. For safer performance of a structure, its foundation should have sufficient strength and stability. Therefore, prior to any reconstruction or rehabilitation of a building subjected to blast, it is important to examine adverse effects on the foundation caused by blast induced ground shocks. This paper evaluates the effects of a buried explosion on a pile foundation. It treats the dynamic response of the pile in saturated sand, using explicit dynamic nonlinear finite element software LS-DYNA. The blast induced wave propagation in the soil and the horizontal deformation of pile are presented and the results are discussed. Further, a parametric study is carried out to evaluate the effect of varying the explosive shape on the pile response. This information can be used to evaluate the vulnerability of piled foundations to credible blast events as well as develop guidance for their design.
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Saccharification of sugarcane bagasse pretreated at the pilot-scale with different processes (in combination with steam-explosion) was evaluated. Maximum glucan conversion with Celluclast 1.5 L (15–25 FPU/g glucan) was in the following order: glycerol/HCl > HCl > H2SO4 > NaOH, with the glycerol system achieving ∼100% conversion. Surprisingly, the NaOH substrate achieved optimum saccharification with only 8 FPU/g glucan. Glucan conversions (3.6–6%) obtained with mixtures of endo-1,4-β-glucanase (EG) and β-glucosidase (βG) for the NaOH substrate were 2–6 times that of acid substrates. However, glucan conversions (15–60%) obtained with mixtures of cellobiohydrolase (CBH I) and βG on acidified glycerol substrate were 10–30% higher than those obtained for NaOH and acid substrates. The susceptibility of the substrates to enzymatic saccharification was explained by their physical and chemical attributes. Acidified glycerol pretreatment offers the opportunity to simplify the complexity of enzyme mixtures required for saccharification of lignocellulosics.
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The preferential invasion of particular red blood cell (RBC) age classes may offer a mechanism by which certain species of Plasmodia regulate their population growth. Asexual reproduction of the parasite within RBCs exponentially increases the number of circulating parasites; limiting this explosion in parasite density may be key to providing sufficient time for the parasite to reproduce, and for the host to develop a specific immune response. It is critical that the role of preferential invasion in infection is properly understood to model the within-host dynamics of different Plasmodia species. We develop a simulation model to show that limiting the range of RBC age classes available for invasion is a credible mechanism for restricting parasite density, one which is equally as important as the maximum parasite replication rate and the duration of the erythrocytic cycle. Different species of Plasmodia that regularly infect humans exhibit different preferences for RBC invasion, with all species except P. falciparum appearing to exhibit a combination of characteristics which are able to selfregulate parasite density.
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Electrostatic discharges have been identified as the most likely cause in a number of incidents of fire and explosion with unexplained ignitions. The lack of data and suitable models for this ignition mechanism creates a void in the analysis to quantify the importance of static electricity as a credible ignition mechanism. Quantifiable hazard analysis of the risk of ignition by static discharge cannot, therefore, be entirely carried out with our current understanding of this phenomenon. The study of electrostatics has been ongoing for a long time. However, it was not until the wide spread use of electronics that research was developed for the protection of electronics from electrostatic discharges. Current experimental models for electrostatic discharge developed for intrinsic safety with electronics are inadequate for ignition analysis and typically are not supported by theoretical analysis. A preliminary simulation and experiment with low voltage was designed to investigate the characteristics of energy dissipation and provided a basis for a high voltage investigation. It was seen that for a low voltage the discharge energy represents about 10% of the initial capacitive energy available and that the energy dissipation was within 10 ns of the initial discharge. The potential difference is greatest at the initial break down when the largest amount of the energy is dissipated. The discharge pathway is then established and minimal energy is dissipated as energy dissipation becomes greatly influenced by other components and stray resistance in the discharge circuit. From the initial low voltage simulation work, the importance of the energy dissipation and the characteristic of the discharge were determined. After the preliminary low voltage work was completed, a high voltage discharge experiment was designed and fabricated. Voltage and current measurement were recorded on the discharge circuit allowing the discharge characteristic to be recorded and energy dissipation in the discharge circuit calculated. Discharge energy calculations show consistency with the low voltage work relating to discharge energy with about 30-40% of the total initial capacitive energy being discharged in the resulting high voltage arc. After the system was characterised and operation validated, high voltage ignition energy measurements were conducted on a solution of n-Pentane evaporating in a 250 cm3 chamber. A series of ignition experiments were conducted to determine the minimum ignition energy of n-Pentane. The data from the ignition work was analysed with standard statistical regression methods for tests that return binary (yes/no) data and found to be in agreement with recent publications. The research demonstrates that energy dissipation is heavily dependent on the circuit configuration and most especially by the discharge circuit's capacitance and resistance. The analysis established a discharge profile for the discharges studied and validates the application of this methodology for further research into different materials and atmospheres; by systematically looking at discharge profiles of test materials with various parameters (e.g., capacitance, inductance, and resistance). Systematic experiments looking at the discharge characteristics of the spark will also help understand the way energy is dissipated in an electrostatic discharge enabling a better understanding of the ignition characteristics of materials in terms of energy and the dissipation of that energy in an electrostatic discharge.
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Numbers, rates and proportions of those remanded in custody have increased significantly in recent decades across a range of jurisdictions. In Australia they have doubled since the early 1980s, such that close to one in four prisoners is currently unconvicted. Taking NSW as a case study and drawing on the recent New South Wales Law Reform Commission Report on Bail (2012), this article will identify the key drivers of this increase in NSW, predominantly a form of legislative hyperactivity involving constant changes to the Bail Act 1978 (NSW), changes which remove or restrict the presumption in favour of bail for a wide range of offences. The article will then examine some of the conceptual, cultural and practice shifts underlying the increase. These include: a shift away from a conception of bail as a procedural issue predominantly concerned with securing the attendance of the accused at trial and the integrity of the trial, to the use of bail for crime prevention purposes; the diminishing force of the presumption of innocence; the framing of a false opposition between an individual interest in liberty and a public interest in safety; a shift from determination of the individual case by reference to its own particular circumstances to determination by its classification within pre‐set legislative categories of offence types and previous convictions; a double jeopardy effect arising in relation to people with previous convictions for which they have already been punished; and an unacknowledged preventive detention effect arising from the increased emphasis on risk. Many of these conceptual shifts are apparent in the explosion in bail conditions and the KPI‐driven policing of bail conditions and consequent rise in revocations, especially in relation to juveniles. The paper will conclude with a note on the NSW Government’s response to the NSW LRC Report in the form of a Bail Bill (2013) and brief speculation as to its likely effects.
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The candidate gene approach has been a pioneer in the field of genetic epidemiology, identifying risk alleles and their association with clinical traits. With the advent of rapidly changing technology, there has been an explosion of in silico tools available to researchers, giving them fast, efficient resources and reliable strategies important to find casual gene variants for candidate or genome wide association studies (GWAS). In this review, following a description of candidate gene prioritisation, we summarise the approaches to single nucleotide polymorphism (SNP) prioritisation and discuss the tools available to assess functional relevance of the risk variant with consideration to its genomic location. The strategy and the tools discussed are applicable to any study investigating genetic risk factors associated with a particular disease. Some of the tools are also applicable for the functional validation of variants relevant to the era of GWAS and next generation sequencing (NGS).
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Zinc oxide (ZnO) that contains non-magnetic ionic dopants, such as nitrogen (N)-doped zinc oxide (ZnO:N), has been observed to exhibit ferromagnetism. Ferromagnetism is proposed to arise from the Coulomb excitation in the localized states that is induced by the oxygen vacancy, V O. A model based on the Coulomb excitation that is associated with the electron–phonon interaction theoretically explains the ferromagnetic mechanism of ZnO:N. This study reveals that the ferromagnetism will be induced by either deep localized states with a small V O concentration or shallow localized states with a high V O concentration. Additionally, electron–phonon coupling either suppresses the ferromagnetism that is induced by the deep donor states of V O or enhances the ferromagnetism that is induced by the shallow donor states of V O.
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This paper presents a comparative study on the response of a buried tunnel to surface blast using the arbitrary Lagrangian-Eulerian (ALE) and smooth particle hydrodynamics (SPH) techniques. Since explosive tests with real physical models are extremely risky and expensive, the results of a centrifuge test were used to validate the numerical techniques. The numerical study shows that the ALE predictions were faster and closer to the experimental results than those from the SPH simulations which over predicted the strains. The findings of this research demonstrate the superiority of the ALE modelling techniques for the present study. They also provide a comprehensive understanding of the preferred ALE modelling techniques which can be used to investigate the surface blast response of underground tunnels.
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Pile foundations transfer loads from superstructures to stronger sub soil. Their strength and stability can hence affect structural safety. This paper treats the response of reinforced concrete pile in saturated sand to a buried explosion. Fully coupled computer simulation techniques are used together with five different material models. Influence of reinforcement on pile response is investigated and important safety parameters of horizontal deformations and tensile stresses in the pile are evaluated. Results indicate that adequate longitudinal reinforcement and proper detailing of transverse reinforcement can reduce pile damage. Present findings can serve as a benchmark reference for future analysis and design.