En brand i en gruva skiljer sig åt jämfört med en brand i en byggnad. Vid brand i en undermarksanläggning uppstår ett omedelbart hot mot de människor som vistas där. Vid en gruvbrand påverkar faktorer såsom sikt, obefintligt dagsljusinsläpp och begränsade utrymningsmöjligheter. Händelserna vid en brand kan också orsaka kostsamma driftstopp i gruvproduktionen. Det finns även en tydlig skillnad i problematik vid räddningsinsatser. Vid en gruvbrand måste räddningstjänsten exempelvis beakta långa inträngningsvägar, begränsade ventilationsmöjligheter, risken för ras och osäker brandvattenförsörjning. Under de senaste tio åren har det inträffat i snitt 70 bränder per år i svenska gruvor, varav cirka hälften varit fordonsrelaterade. Idag installeras därför släcksystem i gruvfordon i syfte att försöka minimera den typen av bränder.   För att kartlägga användandet och erfarenheterna av fordonssläcksystem samt undersöka vilka framtida behov som finns gällande gruvfordons släcksystem och regelverken inom ämnesområdet genomfördes denna förstudie i samråd med RISE.   Förstudien baseras på semi-strukturerade intervjuer med respondenter som valts ut utifrån deras kunskap inom bränder i underjordsgruvor och släcksystem. Även statistik från Gruvindustrins arbetsmiljökommitté gällande bränder i gruvfordon sammanställdes och studerades.   I intervjustudien framgår det att effektiviteten på dagens släcksystem är montörsberoende och att det finns anledning till att konkretisera regelverken och specificera hur släcksystemen bör optimeras. Studien pekar på att effektiviteten hos släcksystem bland annat påverkas av luftflöden, mekanisk påverkan och bristfällig skötsel av systemen. Flera respondenter poängterar även att mängden släckmedelsvätska som används i dagens system måste verifieras gentemot respektive gruvfordons riskprofil. Det finns också en tydlig problematik i verkställandet och noggrannheten av kontroll och underhåll av släcksystemen och respondenterna är eniga om att en förbättring är nödvändig.   Studien visar att ett av de regelverk som tillämpas för släcksystem på fordon i gruvor i Sverige, SBF 127:16, inte beaktar problematiken med bränder i undermarksanläggningar. Det framgår även att de provningarna som genomförs på släcksystem delvis är baserade på information ifrån tidigt 90-tal. Vid verkställande av framtida regelverk bör större hänsyn tas till gruvindustrins specifika behov. År 2018 finns det även en osäkerhet kring fordonssläcksystemens prestanda. Gruvindustrin önskar släcksystem med tillhörande regelverk som är optimerade efter deras behov gällande fordon och miljö.

Businesses with less than 20 employees are regarded as small businesses. The four main types of small business structures are mostly Sole Trader, Partnership, Trust, and Company. E-commerce is the transformation of key commerce processes through the use of the Internet. E-commerce consists of the buying, selling, marketing and servicing of products and services over the Internet. The benefits of E-commerce are reduction in costs, convenient communication and performance of the business process. Several models for E-commerce are Business to Business (B2B), Business to Customer (B2C), Business to Employee (B2E), Business to Government (B2G), and Customer to Customer (C2C). This thesis considers the small typical business structures in Australia to build a framework for small business. Small Business Framework (SBF) is developed to provide a framework to design and implement Web applications for Smart Clients and applications for E-commerce and M-commerce models which are mainly B2B and B2C. The SBF�s components are database, email, electronic payment, products, orders, and login. The technology requirements to operate the SBF are Personal Digital Assistants (PDA), Unicode, Web Server, Visual Studio .NET 2003 (VS .NET) and provision of services through Internet. In order to test and evaluate SBF, an Online Asian Grocery Mobile (OAGM) application has been developed for B2C using MS Visual Studio .NET 2003 (VS.NET). Results showed that the SBF is a good framework for small businesses and the OAGM is a sucessful application prototype since OAGM provides good accessibility, saves time, and is effective.

The biggest challenge with magnesium alloy biodegradable implants is the rapid corrosion at the earlier stages of the healing process after implantation. In this research, the impact of surface roughness generated by different means on the corrosion rate of AZ31 magnesium alloy in a simulated biologic environment is investigated. In order to perform accurate experimentation, an in vitro setup is assembled that simulates the human body environment accurately has been prepared using Schinhammer’s in vitro immersion testing setup and Kokubo’s Simulated Body Fluid (SBF). For the immersion test of Mg in SBF, several surface texture groups of Mg have been prepared and submerged into the in vitro tank. The Mg samples’ comparative analysis has been made in terms of corrosion rate, total weight loss and hydrogen gas evolution within a span of 7 days for the first experiment to narrow down the scope and 14 days for the follow up experiment. After 14 days of in vitro immersion test with varying roughness and hydrophobic modifications such as Cytop coating and stearic acid modification, it has been observed that the roughness group created by etching in aqueous NaCl solution for three minutes, shows better corrosion resistance compared to the polished control group. Hydrophobic modifications on the surfaces did not affect the corrosion behavior significantly.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

This work was focused on the study of hydroxyapatite based bioceramic materials. These materials are generally very important for medical purposes, especially in the reconstruction and replacement of bone material. For medical applications, inert, bioactive or bioresorbable materials can be used. One of the common "bioactive" materials is hydroxyapatite, which forms a large part of human bone. Hydroxyapatite can be prepared by a wide variety of procedures, one of the most common methods is the precipitation reaction used in this work. To improve the biocompatibility of the bone replacement, porous structures with adequate mechanical stability are used. For the initial study of simulation of the behavior of biomaterials in the human body, called in vitro tests are used in solutions based on synthetic body fluids or cell media. The experimental part deals with the synthesis of hydroxyapatite powder and CA phase composite compounds. The reactions between the individual components were studied by thermal analysis and heat microscopy. The resulting products were analyzed for phase composition by X-ray diffraction. The prepared powders were further processed on foam structures by in situ foaming and sintering at a suitable temperature. In vitro tests, following the behavior of the prepared porous products in the synthetic body fluid, were performed for 7, 14 and 28 days. The monitored composites were then studied for biocompatibility by scanning electron microscopy. At the same time, the change in the concentration of Ca2+ and PO43- ions in the body fluids tested was monitored.

Nowadays, magnesium alloys are used in many sectors of human activity, particularly in the aerospace and automotive industries, due to a combination of good mechanical properties and low density of magnesium. Recently, however, the attention is paid to the possibility of using magnesium alloys in the medical field, mainly due to the chemical properties of magnesium. The diploma thesis is focused on evaluating of the corrosion behavior of AZ31alloy and AZ61 alloys in SBF solutions that are solutions simulating body fluids. The alloys were subjected to immersion test in Hank’s solutions for time span from 24 to 1008 hours. The corrosion process was evaluated based on several factors: alloy composition, time and pH changes. The thesis also describes in detail the methodology for establishing magnesium and zinc by method of flame absorption spektrometry (F AAS). The determination of aluminum was carried out by atomic absorption spectrometry with electrothermal atomization (ET AAS).

This thesis deals with the characterization of electrochemical corrosion properties of magnesium alloys as promising materials for biomedical applications. The wrought alloys AZ31 and AZ61 were used and exposed to corrosive environments of Hanks solutions (SBF) to simulate environmental conditions in living organisms. For the evaluation of the surfaces was used scanning electron microscopy (SEM) with elemental analysis measured by energy-dispersive spectroscopy (EDS). Short-term (5 min) and long-term (72 h) corrosion tests were conducted in order to optimize the measurement methodology and obtain corrosion parameters - especially corrosion potential (Ekor), corrosion current density (ikor) and polarisation resistance (RP). To evaluation of the short-term tests were by potentiodynamic tests, namely the linear polarization (LP) test. Long-term tests were measured by electrochemical impedance spectroscopy (EIS). Effects of the composition of the alloys (AZ31 and AZ61), surface treatment (grinding and polishing) and the composition of the solution (SBF without Ca, Mg, and with Ca, Mg) were compared. Complex corrosion behaviour in time was characterized and corrosion mechanisms were discussed.

<p>Software modeling is an integral practice for software engineers especially as the complexity of software solutions increase. There is precedent in industry to model information systems in terms of functions, structures, and behaviors. While constructing these models, abstraction and systems thinking are employed to determine elements essential to the solution and how they are connected. However, both abstraction and systems thinking are difficult to put in practice and difficult to teach due to the, often, ill-structured nature of real-world IT problems. Unified Modeling Language (UML) is the industry standard for software modeling but unfortunately it is often used incorrectly and misunderstood by novices. This has also been observed in educational contexts where students encounter difficulty in employing the appropriate level of abstraction in modeling and programming contexts and not necessarily being able to view or treat software systems as being interconnected. </p> <p>The researcher detailed a multi-methods approach, through the lens of pragmatism, towards understanding patterns of student proficiency with abstraction and software modeling in terms capturing the functional, structural, and behavioral aspects of an information system, as given by the Structures-Behaviors-Function framework. The quantitative strand involved the development of rubrics to analyze functional, structural, and behavioral models given by UML activity diagrams, class diagrams, and sequence diagrams, respectively. The subjects of this study were students enrolled in a sophomore-level systems analysis and design class. Descriptive analysis revealed patterns of modeling proficiency. Students were generally proficient in modeling the system in terms of functions but there was an overall drop-off in proficiency when modeling the system in terms of structures and behaviors. The results of the clustering analysis revealed underlying profiles of students based on abstract thinking and systems thinking ability. Two distinct clusters – high performing students and moderate performing students – were revealed with statistically significant differences between the groups in terms of abstract thinking and systems thinking ability. Further correlational analysis was performed on each cluster. The results of the correlational analyses pointed to significant positive associations between software modeling proficiency and the constructs of abstract thinking and systems thinking. Logistic regression analysis was then performed, and it could be inferred from the regression model that abstract thinking in terms of behaviors and systems thinking in terms of aligning sequence diagrams with activity diagrams were the most important predictors of high performance. </p> The qualitative strand of this study involved a case study approach using the think-aloud protocol centered around exploring how students utilized abstract thinking and systems thinking while constructing software models. The participants of this study were students who had completed the sophomore-level systems analysis and design course. Thematic analysis was utilized to identify themes of abstract thinking and systems thinking within the epistemic games of structural, functional, and process analyses. Two different approaches towards modeling information systems were identified and chronological visualizations for each approach were presented. Overall, it could be inferred from the results and findings of the study that the learning design of the sophomore-level course was successful in equipping students with the skills to proficiently model information systems in terms of functions. However, the students were not as proficient in modeling information systems in terms of structures and behaviors. The theoretical contribution of this study was centered around the application of the SBF framework and epistemic forms and games in the context of information systems. The methodological contributions pertain to the rubrics that were developed which can be used to evaluate software modeling proficiency as well as abstract thinking and systems thinking. Abstract thinking and systems thinking were successfully characterized in the context of information systems modeling. The results of this study have implications in computing education. The suggested instructional approaches and scaffolds can be utilized to improve outcomes in terms of structural and behavioral modeling proficiency.

Die Untersuchung der Reaktionen des Hydroxylradikals mit ungesättigten Kohlenwasserstoffen (Ethin, Ethen, Propen und Isopren) bei tiefen Temperaturen spielt für das Verständnis der Chemie der Troposphäre eine bedeutende Rolle. Aus der Temperaturabhängigkeit der Geschwindigkeitskonstanten können zunächst Informationen über die mechanistischen Details der Reaktionen abgeleitet werden. Dabei sind bimolekulare Geschwindigkeitskonstanten empfindlich auf Details der Potentialfläche in chemisch relevanten Energiebereichen.In der vorliegenden Arbeit werden experimentelle Untersuchungen der Reaktionen des Hydroxylradikals (OH) mit verschiedenen ungesättigten Kohlenwasserstoffen bei tiefen Temperaturen präsentiert. Die Abkühlung der Reaktanden auf bis zu 58K erfolgte durch die Expansion in einer Lavaldüse. Die Lavaldüse erzeugt einen in Temperatur, Dichte und Machzahl konstanten Strahl aus einem Trägergas (Stickstoff). OH- Radikale werden durch Laserphotolyse von Wasserstoffperoxid bei 193 nm und 248 nm erzeugt. Die zeitliche Entwicklung der Hydroxylradikalkonzentration in einem Überschuss des Reaktionspartners wurde mit Hilfe der laserinduzierten Fluoreszenz (LIF) gemessen.Begleitend zu den experimentellen Studien wird eine Abschätzung der bestimmten Geschwindigkeitskonstanten nach dem Modell der statistischen adiabatischen Reaktionskanäle (SACM) durchgeführt. Die Eigenschaften der Edukte und Produkte wurden mit Hilfe von DFT-Methoden berechnet. Die bestimmten Geschwindigkeitskonstanten zwischen 60 und 300K erstrecken sich über zwei Größenordnungen zwischen 10-12 und 10-10 cm3s-1. Dabei ist eine systematische Zunahme der Reaktionsgeschwindigkeiten von Ethin nach Ethen, Propen und Isopren zu erkennen. Weiterhin wird für alle OH-Alken-Reaktionen (zumindest bis 100K) eine negative Temperaturabhängigkeit der Geschwindigkeitskonstanten beobachtet. Diese Tatsachen können durch die Annahme von langreichweitigen Multipol-Wechselwirkungen und den damit verbundenen weit außen liegenden Übergangszuständen der Reaktionen erklärt werden.Für die Reaktionen des OH-Radikals mit Ethin und Ethen wurden Hochdruckgrenzwerte der Reaktionen über die Schwingungsrelaxation des Hydroxylradikals ermittelt. Für die OH-Rekombinationsreaktion des Propens und besonders für Isopren wurde ein Absinken der Geschwindigkeitskonstanten bei Temperaturen unterhalb von 100K gefunden. Ein Effekt, der möglicherweise mit dem Vorhandensein von intermediären Isomeren erklärt werden kann. Die Analyse zeigt, dass die Reaktion OH + Ethin eine deutliche Barriere besitzt, die die geringe Temperaturabhängigkeit im Bereich zwischen 300 und 60K dominiert. Die Reaktion von OH und Ethen zeigt über den gesamten gemessenen Temperaturbereich eine negative Temperaturabhängigkeit.

Se sintetizaron nanocompuestos híbridos en bloque de poli(etil metacrilato-co-hidroxietil acrilato) 70/30 wt%/sílice, P(EMA-co-HEA)/SiO2, con distintas proporciones de sílice hasta el 30 wt%. El procedimiento de síntesis consistió en la copolimerización de los monómeros orgánicos durante la polimerización sol-gel simultánea de tetraetoxisilano, TEOS como precursor de sílice. El TEOS se hidroliza eficientemente y condensa dando lugar a sílice, y presenta una distribución homogénea en forma de agregados inconexos de nanopartículas de sílice elementales en los híbridos con bajos contenidos de sílice (<10 wt%) o redes continuas interpenetradas con la red orgánica tras la coalescencia de los agregados de sílice (>10 wt%). La red polimérica orgánica se forma en los poros producidos en el interior de las nanopartículas elementales de sílice, y también en los poros formados entre los agregados de nanopartículas. Los nanohíbridos con contenidos de sílice intermedios (10-20 wt%) exhibieron las propiedades más equilibradas e interesantes: i) refuerzo mecánico de la matriz orgánica conseguida gracias a redes de sílice continuas e interpenetradas, ii) buena capacidad de hinchado debida a la expansión de la red orgánica no impedida todavía por un esqueleto de sílice rígido, y a un número alto de grupos silanol terminales hidrófilos (concentraciones inorgánicas en los alrededores de la coalescencia), y iii) mayor reactividad superficial debido a un contenido relativo bastante elevado de grupos polares silanol terminales disponibles en las superficies. La 'bioactividad' o capacidad de los materiales en bloque de formar hidroxiapatita (HAp) sobre sus superficies fue estudiada in vitro sumergiéndolos en fluido biológico simulado (simulated body fluid, SBF). La formación de la capa de HAp viene controlada por el mecanismo y el tiempo de inducción a la nucleación de la misma, que dependen a su vez de la estructura de la sílice. / Vallés Lluch, A. (2008). P(EMA-co-HEA)/SiO2 hybrid nanocomposites for guided dentin tissue regeneration: structure, characterization and bioactivity [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/3795