998 resultados para particle creation


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This paper examines the proposition that increased ability to have a voice and be listened to, through ‘open ICT4D’ and ‘open content creation’ can be an effective mechanism for development. The paper discusses empirical work that strongly indicates that this only happens when voice is appropriately valued in the development process. Having a voice in development processes are less effective when participation is limited. Open ICT allows for more and more voices to be heard, but it is open ICT4D that has the obligation to ensure voices are listened to. In the paper I first explore participatory development and the idea of open ICT4D before elaborating on issues of voice and thinking about voice as process, and voice as value. Research findings are presented from research that experimented with participatory (or open) content creation, discussed in relation to notions of openness and voice. I then consider the challenges of listening, before drawing some conclusions about opening up ICT4D research.

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Principal Topic: Resource decisions are critical to the venture creation process, which has important subsequent impacts on venture creation and performance (Boeker, 1989). Most entrepreneurs however, suffer substantial resource constraints in venture creation and during venture growth (Shepherd et al., 2000). Little is known about how high potential, sustainability ventures (the ventures of interest in this research), despite resource constraints, achieve continued venture persistence and venture success. One promising theory that explicitly links to resource constraints is a concept developed by Levi Strauss (1967) termed bricolage. Bricolage aligns with notions of resourcefulness: using what's on hand, through making do, and recombining resources for new or novel purposes (Baker & Nelson 2005). To the best of our knowledge, previous studies have not systematically investigated internal and external constraints, their combinations, and subsequent bricolage patterns. The majority of bricolage literature focuses on external environmental constraints (e.g. Wieck 1989; Baker & Nelson 2005), thereby paying less attention to in evaluating internal constraints (e.g. skills and capabilities) or constraint combinations. In this paper we focus on ventures that typically face resource-poor environments. High potential, nascent and young sustainability ventures are often created and developed with resource constraints and in some cases, have greater resource requirements owing to higher levels of technical sophistication of their products (Rothaermel & Deeds 2006). These ventures usually have high aspirations and potential for growth who ''seeks to meet the needs and aspirations without compromising the ability to meet those of the future'' (Brundtland Commission 1983). High potential ventures are increasingly attributed with a central role in the development of innovation, and employment in developed economies (Acs 2008). Further, increasing awareness of environmental and sustainability issues has fostered demand for business processes that reduce detrimental environmental impacts of global development (Dean & McMullen 2007) and more environmentally sensitive products and services: representing an opportunity for the development of ventures that seek to satisfy this demand through entrepreneurial action. These ventures may choose to ''make do'' with existing resources in developing resource combinations that produce the least impact on the environment. The continuous conflict between the greater requirements for resources and limited resource availability in high potential sustainable ventures, with the added complexity of balancing this with an uncompromising focus on using ''what's on hand'' to lessen environment impacts may make bricolage behaviours critical for these ventures. Research into bricolage behaviour is however, the exception rather than the rule (Cunha 2005). More research is therefore needed to further develop and extend this emerging concept, especially in the context of sustainability ventures who are committed to personal and social goals of resourcefulness. To date, however, bricolage has not been studied specifically among high potential sustainable ventures. This research seeks to develop an in depth understanding of the impact of internal and external constraints and their combinations on the mechanisms employed in bricolage behaviours in differing dynamic environments. The following research question was developed to investigate this: How do internal, external resource constraints (or their combinations) impact bricolage resource decisions in high potential sustainability ventures? ---------- Methodology/Key Propositions: 6 case studies will be developed utilizing survey data from the Comprehensive Australian Study of Entrepreneurial Emergence (CAUSEE) large-scale longitudinal study of new venture start-ups in Australia. Prior to commencing case studies, 6 scoping interviews were conducted with key stakeholders including industry members, established businesses and government to ensure practical relevance in case development. The venture is considered the unit of analysis with the key informant being the entrepreneur and other management team members where appropriate. Triangulation techniques are used in this research including semi-structured interviews, survey data, onsite visits and secondary documentation website analysis, resumes, and business plans. These 6 sustainability ventures have been selected based on different environmental dynamism conditions including a traditionally mature market (building industry) and a more dynamic, evolving industry (renewable energy/solar ventures). In evaluating multidisciplinary literature, we expect the following external constraints are critical including: technology constraints (seen through lock-in of incumbents existing technology), institutional regulation and standards, access to markets, knowledge and training to nascent and young venture bricolage processes. The case studies will investigate internal constraints including resource fungability, resource combination capabilities, translating complex science/engineering knowledge into salient, valuable market propositions, i.e. appropriate market outcomes, and leveraging relationships may further influence bricolage decisions. ---------- Results and Implications: Intended ventures have been identified within the CAUSEE sample and have agreed to participate and secondary data collection for triangulation purposes has already commenced. Data collection of the case studies commenced 27th of May 2009. Analysis is expected to be completed finalised by 25th September 2009. This paper will report on the pattern of resource constraints and its impact on bricolage behaviours: its subsequent impact on resource deployment within venture creation and venture growth. As such, this research extends the theory of bricolage through the systematic analysis of constraints on resource management processes in sustainability ventures. For practice, this research may assist in providing a better understanding of the resource requirements and processes needed for continued venture persistence and growth in sustainability ventures. In these times of economic uncertainty, a better understanding of the influence on constraints and bricolage: the interplay of behaviours, processes and outcomes may enable greater venture continuance and success.

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This paper presents the implementation of a modified particle filter for vision-based simultaneous localization and mapping of an autonomous robot in a structured indoor environment. Through this method, artificial landmarks such as multi-coloured cylinders can be tracked with a camera mounted on the robot, and the position of the robot can be estimated at the same time. Experimental results in simulation and in real environments show that this approach has advantages over the extended Kalman filter with ambiguous data association and various levels of odometric noise.

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Introduction Ovine models are widely used in orthopaedic research. To better understand the impact of orthopaedic procedures computer simulations are necessary. 3D finite element (FE) models of bones allow implant designs to be investigated mechanically, thereby reducing mechanical testing. Hypothesis We present the development and validation of an ovine tibia FE model for use in the analysis of tibia fracture fixation plates. Material & Methods Mechanical testing of the tibia consisted of an offset 3-pt bend test with three repetitions of loading to 350N and return to 50N. Tri-axial stacked strain gauges were applied to the anterior and posterior surfaces of the bone and two rigid bodies – consisting of eight infrared active markers, were attached to the ends of the tibia. Positional measurements were taken with a FARO arm 3D digitiser. The FE model was constructed with both geometry and material properties derived from CT images of the bone. The elasticity-density relationship used for material property determination was validated separately using mechanical testing. This model was then transformed to the same coordinate system as the in vitro mechanical test and loads applied. Results Comparison between the mechanical testing and the FE model showed good correlation in surface strains (difference: anterior 2.3%, posterior 3.2%). Discussion & Conclusion This method of model creation provides a simple method for generating subject specific FE models from CT scans. The use of the CT data set for both the geometry and the material properties ensures a more accurate representation of the specific bone. This is reflected in the similarity of the surface strain results.

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Scientific discoveries, developments in medicine and health issues are the constant focus of media attention and the principles surrounding the creation of so called ‘saviour siblings’ are of no exception. The development in the field of reproductive techniques has provided the ability to genetically analyse embryos created in the laboratory to enable parents to implant selected embryos to create a tissue-matched child who may be able to cure an existing sick child. The research undertaken in this thesis examines the regulatory frameworks overseeing the delivery of assisted reproductive technologies (ART) in Australia and the United Kingdom and considers how those frameworks impact on the accessibility of in vitro fertilisation (IVF) procedures for the creation of ‘saviour siblings’. In some jurisdictions, the accessibility of such techniques is limited by statutory requirements. The limitations and restrictions imposed by the state in relation to the technology are analysed in order to establish whether such restrictions are justified. The analysis is conducted on the basis of a harm framework. The framework seeks to establish whether those affected by the use of the technology (including the child who will be created) are harmed. In order to undertake such evaluation, the concept of harm is considered under the scope of John Stuart Mill’s liberal theory and the Harm Principle is used as a normative tool to judge whether the level of harm that may result, justifies state intervention or restriction with the reproductive decision-making of parents in this context. The harm analysis conducted in this thesis seeks to determine an appropriate regulatory response in relation to the use of pre-implantation tissue-typing for the creation of ‘saviour siblings’. The proposals outlined in the last part of this thesis seek to address the concern that harm may result from the practice of pre-implantation tissue-typing. The current regulatory frameworks in place are also analysed on the basis of the harm framework established in this thesis. The material referred to in this thesis reflects the law and policy in place in Australia and the UK at the time the thesis was submitted for examination (December 2009).

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Along with their essential role in electricity transmission and distribution, some powerlines also generate large concentrations of corona ions. This study aimed at comprehensive investigation of corona ions, vertical dc e-field, ambient aerosol particle charge and particle number concentration levels in the proximity of some high/sub-transmission voltage powerlines. The influence of meteorology on the instantaneous value of these parameters, and the possible existence of links or associations between the parameters measured were also statistically investigated. The presence of positive and negative polarities of corona ions was associated with variation in the mean vertical dc e-field, ambient ion and particle charge concentration level. Though these variations increased with wind speed, their values also decreased with distance from the powerlines. Predominately positive polarities of ions were recorded up to a distance of 150 m (with the maximum values recorded 50 m downwind of the powerlines). At 200 m from the source, negative ions predominated. Particle number concentration levels however remained relatively constant (103 particle cm-3) irrespective of the sampling site and distance from the powerlines. Meteorological factors of temperature, humidity and wind direction showed no influence on the electrical parameters measured. The study also discovered that e-field measurements were not necessarily a true representation of the ground-level ambient ion/particle charge concentrations.

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We alternately measured on-road and in-vehicle ultrafine (<100 nm) particle (UFP) concentration for 5 passenger vehicles that comprised an age range of 18 years. A range of cabin ventilation settings were assessed during 301 trips through a 4 km road tunnel in Sydney, Australia. Outdoor airflow(ventilation) rates under these settings were quantified on open roads using tracer gas techniques. Significant variability in tunnel trip average median in-cabin/on-road (I/O) UFP ratios was observed (0.08 to ∼1.0). Based on data spanning all test automobiles and ventilation settings, a positive linear relationship was found between outdoor air flow rate and I/O ratio, with the former accounting for a substantial proportion of variation in the latter (R2 ) 0.81). UFP concentrations recorded in cabin during tunnel travel were significantly higher than those reported by comparable studies performed on open roadways. A simple mathematical model afforded the ability to predict tunnel trip average in-cabin UFP concentrations with good accuracy. Our data indicate that under certain conditions, in-cabin UFP exposures incurred during tunnel travel may contribute significantly to daily exposure. The UFP exposure of automobile occupants appears strongly related to their choice of ventilation setting and vehicle.

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Compressed natural gas (CNG) engines are thought to be less harmful to the environment than conventional diesel engines, especially in terms of particle emissions. Although, this is true with respect to particulate matter (PM) emissions, results of particle number (PN) emission comparisons have been inconclusive. In this study, results of on-road and dynamometer studies of buses were used to derive several important conclusions. We show that, although PN emissions from CNG buses are significantly lower than from diesel buses at low engine power, they become comparable at high power. For diesel buses, PN emissions are not significantly different between acceleration and operation at steady maximum power. However, the corresponding PN emissions from CNG buses when accelerating are an order of magnitude greater than when operating at steady maximum power. During acceleration under heavy load, PN emissions from CNG buses are an order of magnitude higher than from diesel buses. The particles emitted from CNG buses are too small to contribute to PM10 emissions or contribute to a reduction of visibility, and may consist of semivolatile nanoparticles.

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Background, aim, and scope Urban motor vehicle fleets are a major source of particulate matter pollution, especially of ultrafine particles (diameters < 0.1 µm), and exposure to particulate matter has known serious health effects. A considerable body of literature is available on vehicle particle emission factors derived using a wide range of different measurement methods for different particle sizes, conducted in different parts of the world. Therefore the choice as to which are the most suitable particle emission factors to use in transport modelling and health impact assessments presented as a very difficult task. The aim of this study was to derive a comprehensive set of tailpipe particle emission factors for different vehicle and road type combinations, covering the full size range of particles emitted, which are suitable for modelling urban fleet emissions. Materials and methods A large body of data available in the international literature on particle emission factors for motor vehicles derived from measurement studies was compiled and subjected to advanced statistical analysis, to determine the most suitable emission factors to use in modelling urban fleet emissions. Results This analysis resulted in the development of five statistical models which explained 86%, 93%, 87%, 65% and 47% of the variation in published emission factors for particle number, particle volume, PM1, PM2.5 and PM10 respectively. A sixth model for total particle mass was proposed but no significant explanatory variables were identified in the analysis. From the outputs of these statistical models, the most suitable particle emission factors were selected. This selection was based on examination of the statistical robustness of the statistical model outputs, including consideration of conservative average particle emission factors with the lowest standard errors, narrowest 95% confidence intervals and largest sample sizes, and the explanatory model variables, which were Vehicle Type (all particle metrics), Instrumentation (particle number and PM2.5), Road Type (PM10) and Size Range Measured and Speed Limit on the Road (particle volume). Discussion A multiplicity of factors need to be considered in determining emission factors that are suitable for modelling motor vehicle emissions, and this study derived a set of average emission factors suitable for quantifying motor vehicle tailpipe particle emissions in developed countries. Conclusions The comprehensive set of tailpipe particle emission factors presented in this study for different vehicle and road type combinations enable the full size range of particles generated by fleets to be quantified, including ultrafine particles (measured in terms of particle number). These emission factors have particular application for regions which may have a lack of funding to undertake measurements, or insufficient measurement data upon which to derive emission factors for their region. Recommendations and perspectives In urban areas motor vehicles continue to be a major source of particulate matter pollution and of ultrafine particles. It is critical that in order to manage this major pollution source methods are available to quantify the full size range of particles emitted for traffic modelling and health impact assessments.