878 resultados para Micro-elements


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After 14 years under conventional plough tillage (CT) or conservation minimum tillage (MT), the soil available Al, Fe, Mn, Cu and Zn (0-5, 5-15 and 15-30 cm layers) and their plant uptake were evaluated during two years in a ryegrass-maize forage rotation in NW Spain (t emperate-humid region). The three-way ANOVA showed that trace element concentrations in soil were mainly influenced by sampling date, followed by soil depth and tillage system (35-73 %, 7-58 % and 3- 11 % of variance explained, respectively). Excepting for Fe (CT) and Al (CT and MT), the elemental concentrations decreased with depth, the stratification being stronger under MT. For soil available Al, Fe, Mn and Cu, the concentrations were higher in CT than in MT (5-15 and 15-30 cm layers) or were not affected by tillage system (0-5 cm). In contrast, the available Zn contents were higher in MT than CT at the soil surface and did not differ in deeper layers. The concentration of Al, Fe and Cu in crops were not influenced by tillage system, which explain 22 % of Mn variance in maize (CT > MT in the more humid year) and 18 % of Zn variance in ryegrass (MT > CT in both years). However, in the summer crop (maize) the concentrations of Fe, Mn and Zn tended to be higher in MT than in CT under drought conditions, while the opposite was true in the year without water limitation. Therefore, under the studied conditions of climate, soil, tillage and crop rotation, little influence of tillage system on crop nutritive value would be expected. To minimize the potential deficiency of Zn (maize) and Cu (maize and ryegrass) on crop yields the inclusion of these micro-nutrients in fertilization schedule is reco mmended, as well as liming to alleviate Al toxicity on maize crops.

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Esta Tesis surgió ante la intensidad y verosimilitud de varias señales o “warnings” asociadas a políticas dirigidas a reducir el peso del petróleo en el sector energético, tanto por razones económicas, como geopolíticas, como ambientales. Como tal Tesis se consolidó al ir incorporando elementos novedosos pero esenciales en el mundo petrolífero, particularmente las “tecnologías habilitantes”, tanto de incidencia directa, como el “fracking” como indirecta, del cual es un gran ejemplo el Vehículo Eléctrico (puro). La Tesis se definió y estructuró para elaborar una serie de indagaciones y disquisiciones, que comportaran un conjunto de conclusiones que fueran útiles para las corporaciones energéticas. También para la comprensión de la propia evolución del sector y de sus prestaciones técnicas y económicas, de cara a dar el servicio que los usuarios finales piden. Dentro de las tareas analíticas y reflexivas de la Tesis, se acuñaron ciertos términos conceptuales para explicar más certeramente la realidad del sector, y tal es el caso del “Investment burden”, que pondera la inversión específica (€/W) requerida por una instalación, con la duración del período de construcción y los riesgos tanto tangibles como regulatorios. Junto a ello la Tesis propone una herramienta de estudio y prognosis, denominada “Market integrated energy efficiency”, especialmente aplicable a dicotomías. Tal es el caso del coche térmico, versus coche eléctrico. El objetivo es optimizar una determinada actividad energética, o la productividad total del sector. Esta Tesis propone varias innovaciones, que se pueden agrupar en dos niveles: el primero dentro del campo de la Energía, y el segundo dentro del campo de las corporaciones, y de manera especial de las corporaciones del sector hidrocarburos. A nivel corporativo, la adaptación a la nueva realidad será función directa de la capacidad de cada corporación para desarrollar y/o comprar las tecnologías que permitan mantener o aumentar cuota de mercado. Las conclusiones de la Tesis apuntan a tres opciones principalmente para un replanteamiento corporativo: - Diversificación energética - Desplazamiento geográfico - Beneficiándose de posibles nuevos nichos tecnológicos, como son: • En upstream: Recuperación estimulada de petróleo mediante uso de energías renovables • En downstream: Aditivos orientados a reducir emisiones • En gestión del cambio: Almacenamiento energético con fines operativos Algunas políticas energéticas siguen la tendencia de crecimiento cero de algunos países de la OCDE. No obstante, la realidad mundial es muy diferente a la de esos países. Por ejemplo, según diversas estimaciones (basadas en bancos de datos solventes, referenciados en la Tesis) el número de vehículos aumentará desde aproximadamente mil millones en la actualidad hasta el doble en 2035; mientras que la producción de petróleo sólo aumentará de 95 a 145 millones de barriles al día. Un aumento del 50% frente a un aumento del 100%. Esto generará un curioso desajuste, que se empezará a sentir en unos pocos años. Las empresas y corporaciones del sector hidrocarburos pueden perder el monopolio que atesoran actualmente en el sector transporte frente a todas las demás fuentes energéticas. Esa pérdida puede quedar compensada por una mejor gestión de todas sus capacidades y una participación más integrada en el mundo de la energía, buscando sinergias donde hasta ahora no había sino distanciamiento. Los productos petrolíferos pueden alimentar cualquier tipo de maquina térmica, como las turbinas Brayton, o alimentar reformadores para la producción masiva de H2 para su posterior uso en pilas combustible. El almacenamiento de productos derivados del petróleo no es ningún reto ni plantea problema alguno; y sin embargo este almacenamiento es la llave para resolver muchos problemas. Es posible que el comercio de petróleo se haga menos volátil debido a los efectos asociados al almacenamiento; pero lo que es seguro es que la eficiencia energética de los usos de ese petróleo será más elevada. La Tesis partía de ciertas amenazas sobre el futuro del petróleo, pero tras el análisis realizado se puede vislumbrar un futuro prometedor en la fusión de políticas medioambientales coercitivas y las nuevas tecnologías emergentes del actual portafolio de oportunidades técnicas. ABSTRACT This Thesis rises from the force and the credibility of a number of warning signs linked to policies aimed at reducing the role of petroleum in the energy industry due to economical, geopolitical and environmental drives. As such Thesis, it grew up based on aggregating new but essentials elements into the petroleum sector. This is the case of “enabling technologies” that have a direct impact on the petroleum industry (such as fracking), or an indirect but deep impact (such as the full electrical vehicle). The Thesis was defined and structured in such a way that could convey useful conclusions for energy corporations through a series of inquiries and treatises. In addition to this, the Thesis also aims at understating la evolution of the energy industry and its capabilities both technical and economical, towards delivering the services required by end users. Within the analytical task performed in the Thesis, new terms were coined. They depict concepts that aid at explaining the facts of the energy industry. This is the case for “Investment burden”, it weights the specific capital investment (€/W) required to build a facility with the time that takes to build it, as well as other tangible risks as those posed by regulation. In addition to this, the Thesis puts forward an application designed for reviewing and predicting: the so called “Market integrated energy efficiency”, especially well-suited for dichotomies, very appealing for the case of the thermal car versus the electric car. The aim is to optimize energy related activity; or even the overall productivity of the system. The innovations proposed in this Thesis can be classified in two tiers. Tier one, within the energy sector; and tier two, related to Energy Corporation in general, but with oil and gas corporations at heart. From a corporate level, the adaptation to new energy era will be linked with the corporation capability to develop or acquire those technologies that will yield to retaining or enhancing market share. The Thesis highlights three options for corporate evolution: - diversification within Energy - geographic displacement - profiting new technologies relevant to important niches of work for the future, as: o Upstream: enhanced oil recovery using renewable energy sources (for upstream companies in the petroleum business) o Downstream: additives for reducing combustion emissions o Management of Change: operational energy storage Some energy policies tend to follow the zero-growth of some OECD countries, but the real thing could be very different. For instance, and according to estimates the number of vehicles in use will grow from 1 billion to more than double this figure 2035; but oil production will only grow from 95 million barrel/day to 145 (a 50% rise of versus an intensification of over a 100%). Hydrocarbon Corporation can lose the monopoly they currently hold over the supply of energy to transportation. This lose can be mitigated through an enhanced used of their capabilities and a higher degree of integration in the world of energy, exploring for synergies in those places were gaps were present. Petroleum products can be used to feed any type of thermal machine, as Brayton turbines, or steam reformers to produce H2 to be exploited in fuel cells. Storing petroleum products does not present any problem, but very many problems can be solved with them. Petroleum trading will likely be less volatile because of the smoothing effects of distributed storage, and indeed the efficiency in petroleum consumption will be much higher. The Thesis kicked off with a menace on the future of petroleum. However, at the end of the analysis, a bright future can be foreseen in the merging between highly demanding environmental policies and the relevant technologies of the currently emerging technical portfolio.

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O associativismo empresarial aparece como forma de desenvolvimento regional, seja este econômico, social ou cultural, e é grande aliado para o surgimento e crescimento das micro e pequenas empresas. É um tema já vivenciado e estudado por vários países do mundo, entre eles europeus e especificamente italianos, mas ainda pouco estudado e conhecido no Brasil. A presente pesquisa objetivou analisar o associativismo empresarial entre micro e pequenas empresas (MPEs) na região do Grande ABC (GABC) pelo Projeto Empreender (SEBRAE) relacionando seus dados com os publicados do relatório 2003/5 de autoria do Observatório Europeu de estudos sobre pequenas e médias empresas europeias, analisando as formas de associativismo aqui ocorridas, além de identificar o perfil das empresas e empresários envolvidos no projeto. Para tal análise foram coletados dados de um total de 63 empresas do Projeto Empreender, nos núcleos de Santo André, São Caetano do Sul e Ribeirão Pires. Do GABC foram coletados dados utilizando o instrumento desenvolvido pelo Observatório Europeu de estudos sobre pequenas e médias empresas. A análise dos dados coletados no GABC em relação aos dados europeus se fez necessária para que pudessem ser encontrados pontos de divergências e convergências em cada uma das experiências, objetivando o aprendizado e evolução do tema. A escolha do GABC foi motivada pelo fato da região passar por mudanças no seu perfil econômico, passando de berço e grande pólo das grandes indústrias para um grande centro de pequenas empresas prestadoras de serviços. Após coleta e análise dos dados, percebeu-se que a experiência do GABC e a ocorrida na Itália se parecem em muitos aspectos, porém tem grandes diferenças estruturais. Enquanto o projeto europeu é de responsabilidade de um órgão da União Europeia, aqui o projeto é de autoria do SEBRAE e sofre grandes conflitos com as Associações Comerciais e Industriais (ACIs) da região quando o tema é custeio das despesas das pessoas e estrutura que envolve a implantação do projeto. Além disso, conclui-se que é necessária uma maior aproximação dos municípios com o projeto, tendo em vista que isto poderia ser fator de incentivo a entrada de novas empresas além de fator de aumento de seriedade do sistema. Mais dois dados merecem destaque. Primeiro o fato do Projeto Empreender ter pouca visibilidade regional, ou seja, ser muito pouco divulgado, e o fato da agência de desenvolvimento do GABC não ter aproximação alguma com o projeto. Por último, surgem dados no decorrer da pesquisa que rompem a barreira das teorias administrativas conhecidas, tais como a amizade como fator de associativismo. Portanto, os resultados obtidos com essa pesquisa apontam para a influência no incentivo ao desenvolvimento do processo associativista na região do GABC, além de servir como incentivador para a aproximação de outros atores sociais no processo.(AU)

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O associativismo empresarial aparece como forma de desenvolvimento regional, seja este econômico, social ou cultural, e é grande aliado para o surgimento e crescimento das micro e pequenas empresas. É um tema já vivenciado e estudado por vários países do mundo, entre eles europeus e especificamente italianos, mas ainda pouco estudado e conhecido no Brasil. A presente pesquisa objetivou analisar o associativismo empresarial entre micro e pequenas empresas (MPEs) na região do Grande ABC (GABC) pelo Projeto Empreender (SEBRAE) relacionando seus dados com os publicados do relatório 2003/5 de autoria do Observatório Europeu de estudos sobre pequenas e médias empresas europeias, analisando as formas de associativismo aqui ocorridas, além de identificar o perfil das empresas e empresários envolvidos no projeto. Para tal análise foram coletados dados de um total de 63 empresas do Projeto Empreender, nos núcleos de Santo André, São Caetano do Sul e Ribeirão Pires. Do GABC foram coletados dados utilizando o instrumento desenvolvido pelo Observatório Europeu de estudos sobre pequenas e médias empresas. A análise dos dados coletados no GABC em relação aos dados europeus se fez necessária para que pudessem ser encontrados pontos de divergências e convergências em cada uma das experiências, objetivando o aprendizado e evolução do tema. A escolha do GABC foi motivada pelo fato da região passar por mudanças no seu perfil econômico, passando de berço e grande pólo das grandes indústrias para um grande centro de pequenas empresas prestadoras de serviços. Após coleta e análise dos dados, percebeu-se que a experiência do GABC e a ocorrida na Itália se parecem em muitos aspectos, porém tem grandes diferenças estruturais. Enquanto o projeto europeu é de responsabilidade de um órgão da União Europeia, aqui o projeto é de autoria do SEBRAE e sofre grandes conflitos com as Associações Comerciais e Industriais (ACIs) da região quando o tema é custeio das despesas das pessoas e estrutura que envolve a implantação do projeto. Além disso, conclui-se que é necessária uma maior aproximação dos municípios com o projeto, tendo em vista que isto poderia ser fator de incentivo a entrada de novas empresas além de fator de aumento de seriedade do sistema. Mais dois dados merecem destaque. Primeiro o fato do Projeto Empreender ter pouca visibilidade regional, ou seja, ser muito pouco divulgado, e o fato da agência de desenvolvimento do GABC não ter aproximação alguma com o projeto. Por último, surgem dados no decorrer da pesquisa que rompem a barreira das teorias administrativas conhecidas, tais como a amizade como fator de associativismo. Portanto, os resultados obtidos com essa pesquisa apontam para a influência no incentivo ao desenvolvimento do processo associativista na região do GABC, além de servir como incentivador para a aproximação de outros atores sociais no processo.(AU)

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Building on the ontology of evolutionary realism recently proposed by Dopfer and Potts (forthcoming), we develop an analytical framework for evolutionary economics with a micro-meso-macro architecture. The motive for reconception is to make clear the highly complex and emergent nature of existence and change in economic evolution. For us, the central insight is that an economic system is a population of rules, a structure of rules, and a process of rules. The economic system is a rule-system contained in what we call the meso. From the evolutionary perspective, one cannot directly sum micro into macro. Instead, we conceive of an economic system as a set of meso units, where each meso consists of a rule and its population of actualizations. The proper analytical structure of evolutionary economics is in terms of micro-meso-macro. Micro refers to the individual carriers of rules and the systems they organize, and macro consists of the population structure of systems of meso. Micro structure is between the elements of the meso, and macro structure is between meso elements. The upshot is an ontologically coherent framework for analysis of economic evolution as change in the meso domain - in the form of what we call a meso trajectory - and a way of understanding the micro-processes and macro-consequences involved. We believe that the micro-meso-macro analytical framework can greatly enhance the focus, clarity, and, ultimately, power, of evolutionary economic theory.

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Analysis of intra- and inter-phase distribution of modifying elements in aluminium-silicon alloys is difficult due to the low concentrations used. This research utilises a mu-XRF (X-ray fluorescence) technique at the SPring-8 synchrotron radiation facility X-ray source and reveals that the modifying element strontium segregates exclusively to the eutectic silicon phase and the distribution of strontium within this phase is relatively homogeneous. This has important implications for the fundamental mechanisms of eutectic modification in hypoeutectic aluminium-silicon alloys. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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O associativismo empresarial aparece como forma de desenvolvimento regional, seja este econômico, social ou cultural, e é grande aliado para o surgimento e crescimento das micro e pequenas empresas. É um tema já vivenciado e estudado por vários países do mundo, entre eles europeus e especificamente italianos, mas ainda pouco estudado e conhecido no Brasil. A presente pesquisa objetivou analisar o associativismo empresarial entre micro e pequenas empresas (MPEs) na região do Grande ABC (GABC) pelo Projeto Empreender (SEBRAE) relacionando seus dados com os publicados do relatório 2003/5 de autoria do Observatório Europeu de estudos sobre pequenas e médias empresas europeias, analisando as formas de associativismo aqui ocorridas, além de identificar o perfil das empresas e empresários envolvidos no projeto. Para tal análise foram coletados dados de um total de 63 empresas do Projeto Empreender, nos núcleos de Santo André, São Caetano do Sul e Ribeirão Pires. Do GABC foram coletados dados utilizando o instrumento desenvolvido pelo Observatório Europeu de estudos sobre pequenas e médias empresas. A análise dos dados coletados no GABC em relação aos dados europeus se fez necessária para que pudessem ser encontrados pontos de divergências e convergências em cada uma das experiências, objetivando o aprendizado e evolução do tema. A escolha do GABC foi motivada pelo fato da região passar por mudanças no seu perfil econômico, passando de berço e grande pólo das grandes indústrias para um grande centro de pequenas empresas prestadoras de serviços. Após coleta e análise dos dados, percebeu-se que a experiência do GABC e a ocorrida na Itália se parecem em muitos aspectos, porém tem grandes diferenças estruturais. Enquanto o projeto europeu é de responsabilidade de um órgão da União Europeia, aqui o projeto é de autoria do SEBRAE e sofre grandes conflitos com as Associações Comerciais e Industriais (ACIs) da região quando o tema é custeio das despesas das pessoas e estrutura que envolve a implantação do projeto. Além disso, conclui-se que é necessária uma maior aproximação dos municípios com o projeto, tendo em vista que isto poderia ser fator de incentivo a entrada de novas empresas além de fator de aumento de seriedade do sistema. Mais dois dados merecem destaque. Primeiro o fato do Projeto Empreender ter pouca visibilidade regional, ou seja, ser muito pouco divulgado, e o fato da agência de desenvolvimento do GABC não ter aproximação alguma com o projeto. Por último, surgem dados no decorrer da pesquisa que rompem a barreira das teorias administrativas conhecidas, tais como a amizade como fator de associativismo. Portanto, os resultados obtidos com essa pesquisa apontam para a influência no incentivo ao desenvolvimento do processo associativista na região do GABC, além de servir como incentivador para a aproximação de outros atores sociais no processo.(AU)

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In this paper we summarise key elements of retail change in Britain over a twenty-year period. The time period is that covered by a funded study into long-term change in grocery shopping habits in Portsmouth, England. The major empirical findings—to which we briefly allude—are reported elsewhere: the present task is to assess the wider context underlying that change. For example, it has frequently been stated that retailing in the UK is not as competitive as in other leading economies. As a result, the issue of consumer choice has become increasingly important politically. Concerns over concentration in the industry, new format development and market definition have been expressed by local planners, competition regulators and consumer groups. Macro level changes over time have also created market inequality in consumer opportunities at a local level—hence our decision to attempt a local-level study. Situational factors affecting consumer experiences over time at the local level involve the changing store choice sets available to particular consumers. Using actual consumer experiences thus becomes a yardstick for assessing the practical effectiveness of policy making. The paper demonstrates that choice at local level is driven by store use and that different levels of provision reflect real choice at the local level. Macro-level policy and ‘one size fits all’ approaches to regulation, it is argued, do not reflect the changing reality of grocery shopping. Accordingly, arguments for a more local and regional approach to regulation are made.

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Previous work has shown that human vision performs spatial integration of luminance contrast energy, where signals are squared and summed (with internal noise) over area at detection threshold. We tested that model here in an experiment using arrays of micro-pattern textures that varied in overall stimulus area and sparseness of their target elements, where the contrast of each element was normalised for sensitivity across the visual field. We found a power-law improvement in performance with stimulus area, and a decrease in sensitivity with sparseness. While the contrast integrator model performed well when target elements constituted 50–100% of the target area (replicating previous results), observers outperformed the model when texture elements were sparser than this. This result required the inclusion of further templates in our model, selective for grids of various regular texture densities. By assuming a MAX operation across these noisy mechanisms the model also accounted for the increase in the slope of the psychometric function that occurred as texture density decreased. Thus, for the first time, mechanisms that are selective for texture density have been revealed at contrast detection threshold. We suggest that these mechanisms have a role to play in the perception of visual textures.

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In this study, an Atomic Force Microscopy (AFM) roughness analysis was performed on non-commercial Nitinol alloys with Electropolished (EP) and Magneto-Electropolished (MEP) surface treatments and commercially available stents by measuring Root-Mean-Square (RMS) , Average Roughness (Ra), and Surface Area (SA) values at various dimensional areas on the alloy surfaces, ranging from (800 x 800 nm) to (115 x 115µm), and (800 x 800 nm) to (40 x 40 µm) on the commercial stents. Results showed that NiTi-Ta 10 wt% with an EP surface treatment yielded the highest overall roughness, while the NiTi-Cu 10 wt% alloy had the lowest roughness when analyzed over (115 x 115 µm). Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analysis revealed unique surface morphologies for surface treated alloys, as well as an aggregation of ternary elements Cr and Cu at grain boundaries in MEP and EP surface treated alloys, and non-surface treated alloys. Such surface micro-patterning on ternary Nitinol alloys could increase cellular adhesion and accelerate surface endothelialization of endovascular stents, thus reducing the likelihood of in-stent restenosis and provide insight into hemodynamic flow regimes and the corrosion behavior of an implantable device influenced from such surface micro-patterns.

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Microtubes and rods with nanopipes of transparent conductive oxides (TCO), such as SnO_2, TiO_2, ZnO and In_2O_3, have been fabricated following a vapor-solid method which avoids the use of catalyst or templates. The morphology of the as-grown tubular structures varies as a function of the precursor powder and the parameters employed during the thermal treatments carried out under a controlled argon flow. These materials have been also doped with different elements of technological interest (Cr, Er, Li, Zn, Sn). Energy Dispersive X-ray Spectroscopy (EDS) measurements show that the concentration of the dopants achieved by the vapor-solid method ranges from 0.5 to _3 at.%. Luminescence of the tubes has been analyzed, with special attention paid to the influence of the dopants on their optical properties. In this work, we summarize and discuss some of the processes involved not only in the anisotropic growth of these hollow micro and nanostructures, but also in their doping.

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Abstract How employees make sense of change is a very complex process. Recently, academics have neglected to research sense making activities in a micro culture implementation context, through the eyes of front line employees. In contrast to a macro view, a micro perspective limits researchers to only look at an individual, departmental or group level. By doing so, we can zoom in on the details of sense making processes that employees use in their daily work life. A macro (organisational) view is based on the notion that there is a general integrated culture that can be found in all organisational units and departments. It is assumed that culture can be researched by using the entire organisation as one single research entity. This thesis challenges this assumption. In case of planned change it is usually the management community who are in charge of the change intervention. Because of their formal hierarchical position, they have the power to abort or initiate change programs. It is perhaps therefore that researchers tend to be focused on the management community rather than on lower level organisational members, such as front line employees. Apart from the micro view, scholars also neglected to research culture change implementation through the eyes of front line employees. This thesis is an attempt to fill these two gaps that currently exists in academic change management publications. The main research question is therefore: From a micro point of view how do front-line employees make sense of the impact of culture change, during the implementation phase? This thesis starts with a literature review which exposes the two main gaps. The most important outcome of this review is that only 2% of the research articles dealt with culture implementation, through the eyes of front line employees. A conceptual research model is built on the integrated sense making theory of Weber and Manning (2001) and the micro variables of Raelin and Cataldo (2011). These theories emphasize elements of sense making in a daily working context. It is likely that front line employees can identify themselves with research elements such as tasks, skills practices, involvement and behaviour. Front line employees were selected, because as lower level organisational members they are usually the change recipients. They are further away from the change initiating scene (usually the management of an organisation) and form a potential sense making ‘hotspot’ that could provide new academic insights. In order to carry out the primary research, two case organisations were selected in the leisure industry. A participative case study research method was chosen. This meant that the researcher worked in the concerning departments of the case organisations. The goal was to observe and interview front line employees, while they were performing their jobs. The most important advantage of this approach is that the researcher temporarily becomes one with the organisation and is therefore able to acquire both formal and informal narratives that front line employees use during sense making activities. It was found that front line employees make sense of organisational change by using a practical approach. They make sense of the change program by carrying out new tasks, developing new skills and sharing best practices. The most noticeable conclusion was that sense making activities predominantly take place at an individual level in relation to change acceptance. Organisational members tend to create a mental equation in order to weigh the advantages against the disadvantages. They evaluate whether the concerning change program is beneficial to them or not. For future research a sense making scheme model is suggested that is based on two methods: an introspection and an action method.

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Miniaturization of power generators to the MEMS scale, based on the hydrogen-air fuel cell, is the object of this research. The micro fuel cell approach has been adopted for advantages of both high power and energy densities. On-board hydrogen production/storage and an efficient control scheme that facilitates integration with a fuel cell membrane electrode assembly (MEA) are key elements for micro energy conversion. Millimeter-scale reactors (ca. 10 µL) have been developed, for hydrogen production through hydrolysis of CaH2 and LiAlH4, to yield volumetric energy densities of the order of 200 Whr/L. Passive microfluidic control schemes have been implemented in order to facilitate delivery, self-regulation, and at the same time eliminate bulky auxiliaries that run on parasitic power. One technique uses surface tension to pump water in a microchannel for hydrolysis and is self-regulated, based on load, by back pressure from accumulated hydrogen acting on a gas-liquid microvalve. This control scheme improves uniformity of power delivery during long periods of lower power demand, with fast switching to mass transport regime on the order of seconds, thus providing peak power density of up to 391.85 W/L. Another method takes advantage of water recovery by backward transport through the MEA, of water vapor that is generated at the cathode half-cell reaction. This regulation-free scheme increases available reactor volume to yield energy density of 313 Whr/L, and provides peak power density of 104 W/L. Prototype devices have been tested for a range of duty periods from 2-24 hours, with multiple switching of power demand in order to establish operation across multiple regimes. Issues identified as critical to the realization of the integrated power MEMS include effects of water transport and byproduct hydrate swelling on hydrogen production in the micro reactor, and ambient relative humidity on fuel cell performance.

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Elemental analysis can become an important piece of evidence to assist the solution of a case. The work presented in this dissertation aims to evaluate the evidential value of the elemental composition of three particular matrices: ink, paper and glass. In the first part of this study, the analytical performance of LIBS and LA-ICP-MS methods was evaluated for paper, writing inks and printing inks. A total of 350 ink specimens were examined including black and blue gel inks, ballpoint inks, inkjets and toners originating from several manufacturing sources and/or batches. The paper collection set consisted of over 200 paper specimens originating from 20 different paper sources produced by 10 different plants. Micro-homogeneity studies show smaller variation of elemental compositions within a single source (i.e., sheet, pen or cartridge) than the observed variation between different sources (i.e., brands, types, batches). Significant and detectable differences in the elemental profile of the inks and paper were observed between samples originating from different sources (discrimination of 87 – 100% of samples, depending on the sample set under investigation and the method applied). These results support the use of elemental analysis, using LA-ICP-MS and LIBS, for the examination of documents and provide additional discrimination to the currently used techniques in document examination. In the second part of this study, a direct comparison between four analytical methods (µ-XRF, solution-ICP-MS, LA-ICP-MS and LIBS) was conducted for glass analyses using interlaboratory studies. The data provided by 21 participants were used to assess the performance of the analytical methods in associating glass samples from the same source and differentiating different sources, as well as the use of different match criteria (confidence interval (±6s, ±5s, ±4s, ±3s, ±2s), modified confidence interval, t-test (sequential univariate, p=0.05 and p=0.01), t-test with Bonferroni correction (for multivariate comparisons), range overlap, and Hotelling’s T2 tests. Error rates (Type 1 and Type 2) are reported for the use of each of these match criteria and depend on the heterogeneity of the glass sources, the repeatability between analytical measurements, and the number of elements that were measured. The study provided recommendations for analytical performance-based parameters for µ-XRF and LA-ICP-MS as well as the best performing match criteria for both analytical techniques, which can be applied now by forensic glass examiners.

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A miniaturised gas analyser is described and evaluated based on the use of a substrate-integrated hollow waveguide (iHWG) coupled to a microsized near-infrared spectrophotometer comprising a linear variable filter and an array of InGaAs detectors. This gas sensing system was applied to analyse surrogate samples of natural fuel gas containing methane, ethane, propane and butane, quantified by using multivariate regression models based on partial least square (PLS) algorithms and Savitzky-Golay 1(st) derivative data preprocessing. The external validation of the obtained models reveals root mean square errors of prediction of 0.37, 0.36, 0.67 and 0.37% (v/v), for methane, ethane, propane and butane, respectively. The developed sensing system provides particularly rapid response times upon composition changes of the gaseous sample (approximately 2 s) due the minute volume of the iHWG-based measurement cell. The sensing system developed in this study is fully portable with a hand-held sized analyser footprint, and thus ideally suited for field analysis. Last but not least, the obtained results corroborate the potential of NIR-iHWG analysers for monitoring the quality of natural gas and petrochemical gaseous products.