The Use of Numerical Methods to Interpret Polymer Decomposition Data

Polymer decomposition is the key to understanding fire behaviour. It is a complex process involving heat transfer, breakdown of the polymer chain, volatile fuel formation and gasification occurring as a moving interface through the polymer bulk. Two techniques, chemical analysis using STA-FTIR, and pyrolysis modelling have been combined as a tool to better understand these processes. This work covers the experimental investigation of polymer decomposition using the STA-FTIR technique. Several polymers including polyacrylonitrile (PAN), polypropylene (PP) and ethylene-vinyl acetate (EVA) alone, and as potential fire retardant composites have been studied in different conditions to optimise the methodology and analysis of results. Polyacrylonitrile was used to optimise the experimental technique. Polypropylene, containing nanoclay and ammonium phosphate, was decomposed and the composition of the decomposition products analysed in order to investigate the fire retardant effects of the additives on the thermal decomposition. Ethylene-vinyl acetate copolymer containing nanoclay and/or either aluminium hydroxide or magnesium hydroxide was decomposed, with vapour phase FTIR analysis showing a change in the initial decomposition pathway with a shift from acetic acid evolution, to acetone production. In parallel, this experimental data has been used to perform early attempts towards validation of numerical models developed by the use of a 1-dimensional pyrolysis computational tool called ThermaKin. As ThermaKin is relatively new and still not widely used for fire modelling, a detailed description of its capabilities has been provided. A detailed study of heat transfer of cardboard, leading to thermal decomposition, accompanied by pyrolysis and char formation has been described. Several microscale kinetics models have been proposed with different levels of complexity. Not only do the numerical approximations reflect the experimental results of single compounds, describing the material’s behaviour (expressed in terms of mass loss) when exposed to external heat, but also predictive models of fire retardant mixtures have been developed for different atmospheres and heating rates. In addition, the powerful combination of pyrolysis modelling and chemical analysis by STA-FTIR has provided new insights into the decomposition and burning behaviour of both PP protected with nanoclay and ammonium phosphate, but also the industrially important cable sheathing materials based on EVA. The novelty of this work stems from the first use of the pyrolysis models to study fire retardant behaviour; the first reported combination of STA-FTIR with ThermaKin pyrolysis model, and a deep understanding of the pre-ignition behaviour of cardboard

Investigation on Aerodynamics of Super–Effective Car for Drag Reduction.

This paper focuses on shape optimization of a car body to be used in Shell Eco Marathon race. The work consists of the review of aerodynamic performance for currently used shapes, definition of the design constraints for the vehicle and recommendations for the final shape to be used in the oncoming Shell Eco Marathon editions. The designs are inspired by winning models, but adjusted to Iron Warriors technology and scaled accordingly to the driver’s space requirements. A range of velocities from 20 km/h to 45 km/h with 5 km/h interval is tested, giving idea about the full model performance. Results are then compared and the best solutions, concerning the coefficient and parameter taking into account the frontal area influence are recommended

Wearing Colored Glasses

本论文主要针对木子美的《遗情书》文学内容进行研究。在2003年被审查之前，木子美现象引起了中国广大网民的极大反响，可谓赞誉皆有。本文将不会对该现象引起的反应进行研究，也不会试图给这种事件贴上性权益、女权、产权等标签，反之，本文将关注木子美的博客本身，并分析她的语言使用。隐喻是如何在现代与性相关的词汇中进行使用，来使得“性”在中国正常化？英语如何在现代中文俚语中起作用？隐秘的性词汇是如何阻碍女性用积极的方式来表达她们的性感受？为什么大部分正常人无法评估和表达他们自身的性感受或者甚至其行为？那些轻蔑贬低的措辞能得以改善么？中文本身的视觉特性是否阻碍了彻底的改革？以一种缩小隐喻和文化偏见的方式来看待...The primary focus of this study is Mu Zimei’s Love Letters Left Behind as a literary text. The Mu Zimei phenomenon caught the attention of millions of Chinese netizens before its censorship in 2003, yielding varying degrees of acclaim and vilification. Instead of analyzing the reactions to the ‘phenomenon’ and trying to label the phenomological event as writing about sexual rights, women’s right...学位：哲学硕士院系专业：人文学院_中国哲学学号：1012011115436

An experimental and numerical model for the release of acetone from decomposing EVA containing aluminium, magnesium or calcium hydroxide fire retardants

Recent studies have identified acetone as an unexpected pyrolysis product of EVA containing aluminium or magnesium hydroxide fire retardants. It is thought that the freshly formed, open-pored, metal oxide, a thermal decomposition product of the metal hydroxide, traps acetic acid released from EVA and catalyses its conversion to acetone. Such a ketonisation reaction is well-established but the intermediate steps that result in acetic acid conversion to acetone in the presence of a metal oxide, trapped within the polymer matrix, have not been reported. This study used three model metal acetates: aluminium acetate, magnesium acetate and calcium acetate, to chemically represent the proposed metal acetate intermediate complexes. This provides crucial information on the kinetics of acetic acid trapping and subsequent acetone release during decomposition studied by TGA-FTIR, which has been used to generate kinetic models within a pyrolysis programme (ThermaKin), in order to quantitatively understand the processes occurring in fire retardant EVA. The benefit of using metal acetates is that they are simple enough to allow isolation of the chemical process of interest from the complications of acetic acid release from EVA and transport through the polymer matri

Subcritical axisymmetric solutions in rotor-stator flow

Rotor-stator cavity flows are known to exhibit unsteady flow structures in the form of circular and spiral rolls. While the origin of the spirals is well understood, that of the circular rolls is not. In the present study the axisymmetric flow in an aspect ratio $R/H=10$ cavity is revisited {numerically using recent concepts and tools from bifurcation theory}. It is confirmed that a linear instability takes place at a finite critical Reynolds number $Re=Re_c$, and that there exists a subcritical branch of large amplitude chaotic solutions. This motivates the search for subcritical finite-amplitude solutions. The branch of periodic states born in a Hopf bifurcation at $Re=Re_c$, identified using a Self-Consistent Method (SCM) and arclength continuation, is found to be supercritical. The associated solutions only exist, however, in a very narrow range of $Re$ and do not explain the subcritical chaotic rolls. Another subcritical branch of periodic solutions is found using the Harmonic Balance Method with an initial guess obtained by SCM. In addition, edge states separating the steady laminar and chaotic regimes are identified using a bisection algorithm. These edge states are bi-periodic in time for most values of $Re$, {where} their dynamics is {analysed in detail}. Both solution branches fold around at approximately the same value of $Re$, which is lower than $Re_c$ yet still larger than the values reported in experiments. This suggests that, at least in the absence of external forcing, sustained chaotic rolls have their origin in the bifurcations from these unstable solutions

Ostry zespół wieńcowy z uniesieniem odcinka ST u pacjenta przewlekle leczonego doustnym antykoagulantem

Approximately 6–8% of patients undergoing percutaneous coronary interventions (PCI) have an indication for long-term oral anticoagulation with vitamin K antagonists (VKA) or novel oral anticoagulants due to various conditions. Primary PCI with adjunctive pharmacological therapy for ST-elevation myocardial infarction (STEMI) patients on chronic VKA treatment carry increased risk of bleeding, however, very few studies are available so far. We describe a patient, who presented with STEMI and international normalized ratio of 4.5 and discuss possible treatment options.Około 6–8% pacjentów poddawanych przezskórnej angioplastyce wieńcowej (PCI) ma wskazania do przewlekłej terapii przeciwkrzepliwej antagonistami witaminy K (VKA) lub nowymi lekami antykoagulacyjnymi. Pierwotna PCI u pacjenta leczonego dodatkowo z powodu zawału serca z uniesieniem odcinka ST (STEMI), poddanego jednocześnie przewlekłej terapii VKA, jest obarczona istotnie zwiększonym ryzykiem krwawienia. Dostępnych jest jednak niewiele badań odnoszących się do tego ważnego scenariusza klinicznego. Opisano pacjenta ze STEMI, u którego wyjściowy międzynarodowy współczynnik znormalizowany wynosił 4,5