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1
GRASSI, DAVIDE. "Tecnologie innovative per il consolidamento di substrati di fondazione e opere geotecniche." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/366246.
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The PhD research activities are focused on ground improvement application. The objective is to study the permeation grouting technique in granular soils and to understand the hydro-mechanical properties that can be obtained using non-conventional injection materials.
During the project it has been developed an injection apparatus and a monitoring system of the grouting process that is used to study the permeation process and to develop a theoretical, and then analytical and numerical approach. Furthermore, the injection apparatus is used to simulate the permeation of different injection materials in soils and to generate specimen for hydraulic and mechanical evaluations.
The experimental set-up comprises of a polycarbonate extruded clear tube, 50 mm in inner diameter and variable length (with a maximum of 1.6 m), and two floating caps at the extremities with a double sealing system. Once it has been filled with a selected soil it is inserted in a rigid steel chassis and the hole injection system can support 100 bar injection pressure. To simulate the soil micro-mechanical behavior has been created a loading system, composed by a screw that can apply a confining pressure on the soil sample.
The column is then instrumented:
• two load cells to control the confining pressure;
• five pressure transducers to control the imposed pressure;
• two pressure switches to impose pressure to the fluid;
• laser ranging distance sensors to measure the flow rate;
• vision camera to detect fluid front advancement.
The data from the sensors are collected by employing Arduino processors and all the results are elaborated and displayed in real time with a Labview platform software. Some of the sensors were properly calibrated after being installed and all the measurements and the injection apparatus are validated before starting the test.
The injection apparatus has been used to test different conventional and non-conventional grout with different rheological properties: sodium silicate, acrylic resin, colloidal silica, cement and micro-cement grout. For some of the previous injection materials have been defined a rheological time-dependent law. All these tests have been used to understand the permeation phenomena and to define an analytical and numerical predictive model that could be valid for all the soil in all conditions. By using this approach and by knowing the soil hydraulic properties, related to a new geotechnical project, it should be possible to indicate to designers the type of grout, the injection parameters and the injection geometry for this specific ground improvement application.
Finally, a hydro-mechanical investigation of the different injection materials has been performed, consisting of the following test: permeability, unconfined compressive strength, triaxial test and brasilian test. For each injection test it has been evaluated the difference mechanical behavior from the bottom to the top part of the column, resulting from a variable soil saturation during the permeation process, that, in a ground with a grout spherical propagation, can be related to the radial distance from the injection point. Furthermore, a mechanical comparison, in term of friction angle and cohesion, is performed for the different grout types and, for some of them, at different curing time.The PhD research activities are focused on ground improvement application. The objective is to study the permeation grouting technique in granular soils and to understand the hydro-mechanical properties that can be obtained using non-conventional injection materials. During the project it has been developed an injection apparatus and a monitoring system of the grouting process that is used to study the permeation process and to develop a theoretical, and then analytical and numerical approach. Furthermore, the injection apparatus is used to simulate the permeation of different injection materials in soils and to generate specimen for hydraulic and mechanical evaluations. The experimental set-up comprises of a polycarbonate extruded clear tube, 50 mm in inner diameter and variable length (with a maximum of 1.6 m), and two floating caps at the extremities with a double sealing system. Once it has been filled with a selected soil it is inserted in a rigid steel chassis and the hole injection system can support 100 bar injection pressure. To simulate the soil micro-mechanical behavior has been created a loading system, composed by a screw that can apply a confining pressure on the soil sample. The column is then instrumented: • two load cells to control the confining pressure; • five pressure transducers to control the imposed pressure; • two pressure switches to impose pressure to the fluid; • laser ranging distance sensors to measure the flow rate; • vision camera to detect fluid front advancement. The data from the sensors are collected by employing Arduino processors and all the results are elaborated and displayed in real time with a Labview platform software. Some of the sensors were properly calibrated after being installed and all the measurements and the injection apparatus are validated before starting the test. The injection apparatus has been used to test different conventional and non-conventional grout with different rheological properties: sodium silicate, acrylic resin, colloidal silica, cement and micro-cement grout. For some of the previous injection materials have been defined a rheological time-dependent law. All these tests have been used to understand the permeation phenomena and to define an analytical and numerical predictive model that could be valid for all the soil in all conditions. By using this approach and by knowing the soil hydraulic properties, related to a new geotechnical project, it should be possible to indicate to designers the type of grout, the injection parameters and the injection geometry for this specific ground improvement application. Finally, a hydro-mechanical investigation of the different injection materials has been performed, consisting of the following test: permeability, unconfined compressive strength, triaxial test and brasilian test. For each injection test it has been evaluated the difference mechanical behavior from the bottom to the top part of the column, resulting from a variable soil saturation during the permeation process, that, in a ground with a grout spherical propagation, can be related to the radial distance from the injection point. Furthermore, a mechanical comparison, in term of friction angle and cohesion, is performed for the different grout types and, for some of them, at different curing time.
2
Mazzon, Nicola. "Infuence of Grout Injection on the Dynamic Behaviour of Stone Masonry Buildings." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3422728.
Full textAbstract:
The Italian and European regions are characterized by a wide diffusion of structures in the minor historical centres. The decay condition, in which part these buildings are, makes often necessary structural interventions to preserve they integrity. This way, during last decades several new intervention methodologies were developed, employing both innovative and traditional materials, with the aim to avoid further damages, particularly those induced by seismic events. However, these new materials and techniques are often commercialized and employed without any preliminary exhaustive study to verify their applicability and their effectiveness.
The present research joins in this contest considering the multi-leaf stone masonries, one of the most diffuse structural systems widely employed on minor historical buildings. This masonry typology is constituted by more approached leaves and it is characterized by a high percentage of internal voids. Furthermore, the employment of hydraulic lime-based grout injection is also considered as strengthening technique suitable for this masonry typology. This study aims to validate the application of this intervention methodology, widely applied since many years employing materials different for chemical composition, trough an extensive experimental campaign and a subsequent numerical modelling.
First experimental phase involves a series of dynamic tests on whole building models, considering a reducing scale factor, realized with multi-leaf stone masonry, subsequently strengthened trough injection of grout. The execution of these shaking table tests allowed to evaluate the influence of the considered strengthening technique on the overall dynamic behaviour of the injected structure. Furthermore, also the increasing of strength and the seismic response of the building models could be evaluated.
A complementary experimental phase involved several further quasi-static laboratory tests tests on single structural elements.
Compression tests allowed to study the strength increasing of this elements as well as their failure mechanisms after the grout injection. Further shear compression tests provided important informations about the mechanical behaviour of single structural elements subjected to in-plane cyclic forces.
Finally, a numerical modelling of the mechanical behaviour of specimens subjected to compression load was developed. This analysis allowed to deepen the study of the stress distribution and of the failure mechanisms of single structural elements subjected to strengthening trough grout injection.Il territorio italiano, così come quello europeo, è caratterizzato da un’ampia diffusione di strutture appartenenti all’edilizia storica minore. Lo stato di degrado, in cui talvolta si trovano tali edifici, rende spesso necessari interventi strutturali volti a garantirne l’integrità. In tale senso, negli ultimi decenni sono state sviluppate nuove metodologie d’intervento, sfruttando sia di materiali tradizionali che innovativi, per preservare tali strutture da ulteriori danni, in particolare quelli indotti da eventi sismici. Tuttavia, nuovi materiali e tecniche d’intervento vengono spesso commercializzati ed applicati senza l’esecuzione di un esaustivo studio preliminare che ne verifichi l’applicabilità e l’efficacia. La presente ricerca si inserisce in questo contesto prendendo in considerazione le murature multi-strato in pietra, una delle tipologie costruttive maggiormente impiegate nell’edilizia storica minore. Tale muratura è costituita da più paramenti accostati ed è caratterizzata da un’alta percentuale di vuoti interni. Inoltre, si considera l’impiego dell’iniezione di miscela, a base di calce idraulica naturale, come tecnica di consolidamento applicabile a tale tipologia muraria. Lo studio si propone di validare l’impiego di questa metodologia d’intervento, già da tempo ampiamente utilizzata sfruttando materiali di diversa composizione chimica, mediante la realizzazione di un’ampia campagna sperimentale e di una successiva modellazione numerica. La prima fase sperimentale comprende una serie di prove dinamiche su modelli di edificio, in scala ridotta, realizzati in muratura multi-strato di pietra, successivamente sottoposta ad iniezione di miscela. L’esecuzione di tali prove su tavola vibrante ha permesso di valutare l’influenza della tecnica di consolidamento considerata sul comportamento dinamico globale della struttura su cui si interviene. Inoltre, si è potuto valutare l’incremento di resistenza oltre che la variazione della risposta sismica dei modelli di edificio. Una complementare fase sperimentale ha coinvolto numerose ed ulteriori prove di laboratorio, realizzate in ambito quasi-statico, su singoli elementi strutturali.L’esecuzione di prove di compressione ha permesso di verificare sia l’incremento di resistenza di tali elementi strutturali che la variazione delle loro modalità di rottura a seguito dell’iniezione di miscela legante. Ulteriori prove di taglio e compressione hanno fornito importanti indicazioni riguardo al comportamento meccanico di singoli elementi strutturali soggetti a forze cicliche nel piano. Infine, si è sviluppata una modellazione numerica del comportamento meccanico di campioni sottoposti a carico di compressione monoassiale. Quest'analisi ha dunque permesso di approfondire lo studio della distribuzione delle tensioni e delle modalità di rottura di singoli elementi strutturali, soggetti ad intervento di consolidamento mediante iniezioni di miscela legante.
3
Hennessy, Phillippa. "Modelling group communication." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291732.
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4
Ford, Peter S. "Development of crystallographic surfaces for modelling interactions." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4776/.
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This thesis addresses two separate problems - an investigation of the interaction of probe molecules with crystalline rutile and an investigation of the environment of group IA and IIA elements in organometallic compounds. Ab-initio Hartree-Fock calculations have been performed, aimed at investigating the interactions between the ionic surface of a crystal and an adsorbate molecule. Titanium dioxide, a material important for catalysis, electronic components and pigments, was chosen as the substrate, with carbon monoxide as the probe molecule. The calculations were carried out using the Crystal92 program, for the (110) surface of the Rutile polymorph of TiO(_2), employing a slab with a thickness of 5 atomic layers. The calculations investigated two orientations of the CO molecule with the molecular axis perpendicular to the surface. Results are reported showing contour diagrams for slices through the energy hypersurface parallel and perpendicular to the surface of the substrate. In order to facilitate the work described above, a program 'Builder2' was developed. This provides a convenient means for generating models of slabs of material from crystal structure data. Part of the development of Builder2 was to devise computer code to decompose standard Space Group symbols into the underlying symmetry matrices. The code for Builder2 is proprietary to Oxford Materials Ltd. and forms part of a commercial product. The environment of group IA and IIA elements in crystalline materials has not been the subject of any reported investigation. These elements, and organic ligands associated with them, play a significant role in biological systems. Around 16,000 atomic environments were extracted from the Cambridge Crystallographic Database to provide an up-to-date analysis of actual environments. The results are presented as histograms and tables, and suggestions are made for future extension of the analyses.
5
France, Emma F. "Modelling the multi in multi-party multimedia communication." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321996.
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Subramanya, Shreyasu. "Modelling and Simulation of Fan Performance using CFD Group." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-171106.
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Performance of vacuum cleaners are affected by factors such static pressure, airflow rate and efficiency. In this thesis work, attempt has been made to design a fan to meet the requirements of suction static pressure and air flow rate and in the process understand the fan design parameters that affect these performance parameters. Parametric study has been conducted for the same, by choosing six fan design parameters. Additionally, ways to increase the fan efficiency has been investigated during the parametric study. Computational Fluid Dynamics is used to visualize the flow inside the fan casing and further to simulate fan performance at an operational point. Steady state RANS and moving reference frames was used to model the turbulence in the fluid flow and rotation of the fan, respectively. Performance curve showing the relation between static suction pressure and mass flow rate is plotted for the base model is in proximity to the required performance. Parametric study was conducted on the six fan design parameters: Fan diameter, number of impeller blades, blade outlet angle, radius of the curve connecting inlet to outlet section of the fan, diffuser exit length and splitter blade length. The range for each parameter analysis was restricted so that static pressure values are around the required performance. Greater performance variation was found with design parameters: fan diameter, blade outlet angle, radius of the curve connecting inlet to outlet section of the fan and diffuser exit length. This variation at low mass flow rate can be majorly attributed to the randomness in the flow captured by entropy contours. At high mass flow rate, blockage in the flow visualized by pressure contours reasoned for the performance variation. Greater performance variation was not when design parameters such as number of blades and splitter blade length were varied. Larger variation of these parameters is required to see better variation.
7
Hu, Wei. "Physical modelling of group behaviour of stone column foundations." Thesis, Connect to e-thesis, 1995. http://theses.gla.ac.uk/817/.
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Thesis (Ph.D.) - University of Glasgow, 1995.Ph.D. thesis submitted to the Faculty of Engineering, Department of Civil Engineering, Unversity of Glasgow, 1995. Includes bibliographical references. Print version also available.
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Fujita, Naomi. "Modelling of point and extended defects in Group IV semiconductors." Thesis, University of Exeter, 2009. http://hdl.handle.net/10036/90563.
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In this thesis first-principles calculations of point and extended defects in diamond and silicon are reported. In single crystal diamond grown by chemical vapour deposition (CVD) dislocations are observed as mixed-type 45° and edge-type dislocations lying along <100> with 1/2<110> Burgers vectors. Results are presented on the core structures, core energies and electrical properties of both types of dislocations and their interaction with nitrogen is investigated. Then the focus turns to the brown diamond problem. Despite concerted research efforts, the origin of the brown colouration of diamond is still under discussion. Recently, the attention was drawn to vacancy-related defects. Experiments on type IIa diamonds indicate that the brown colour is caused by vacancy-type extended defects, however the shape and size of these defects remained unclear. In this work, the structural, electrical and optical properties of large spherical vacancy clusters and thin vacancy disks are investigated by means of density functional theory and the calculations are compared with recent experimental measurements on brown diamond. High pressure high temperature treatment (HPHT) of brown type Ia diamonds above 2000°C results in the loss of the brown colour and the formation of nitrogen-vacancy defects. The generation of such defects requires a source of mobile vacancies during the annealing process. It is suggested that the vacancy cluster model described in this thesis can explain the observed annealing behaviour since the break-up of the clusters leads to a supersaturation of mobile vacancies which readily complex with substitutional nitrogen atoms present in the material. Therefore, the effect of HPHT treatment of brown type Ia diamond is investigated by studying the formation energies of common and rare defects and estimates of their equilibrium concentrations at different annealing stages are given. Finally, an open problem also involving nitrogen, but in a different group IV semiconductor is considered. In Czochralski-silicon, nitrogen-related shallow thermal donors are formed between 500 and 750°C. Until now the exact chemical composition and atomic structure of these defects are not well established. Here, it is shown that NO and NO_2 belong to the family of nitrogen-oxygen related shallow thermal donors. Based on the law of mass action the equilibrium defect concentrations are predicted. Finally, the theoretical results are compared to recent Fourier transform infrared (FTIR) spectroscopy measurements.
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Padilha, Emiliano Gomes. "Modelling turn-taking in a simulation of small group discussion." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/1679.
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The organization of taking turns at talk is an important part of any verbal interaction such as conversation, particularly in groups. Sociologists and psycholinguists have been studying turn-taking in conversation through empirical and statistical analysis, and identified some systematics in it. But to my knowledge no detailed computational modelling of verbal turn-taking has yet been attempted. This thesis describes one such attempt, for a simulation of small group discussion— that is, engaged conversation in groups of up to seven participants, which researchers have found to be much like two-person dialogues with overhearers. The group discussion is simulated by a simple multi-agent framework with a blackboard architecture, where each agent represents a participant in the discussion and the blackboard is their channel of communication, or ‘environment’ of the discussion. Agents are modelled with just a set of probabilistic parameters that give their likelihood of doing the various turn-taking decisions in the simulation: when to talk, when to continue talking, when to interrupt, when to give feedback (“uh huh”), and so on. The simulation, therefore, consists of coordinating a one-at-a-time talk (symbolic talk) with speaker transitions, hesitation, yielding or keeping the floor, and managing simultaneous talk which occurs mostly around speaker transitions. The turn-taking modelling considers whether participants are talking or not, and when they reach points of possible completion in their utterances that correspond to the places of transition-relevance, TRPs, where others could start to speak in attempts to take a new turn of talk. The agent behaviours (acts), their internal states and procedures are then described. The model is expanded with elaborate procedures for the resolution of simultaneous talk, for speaking hesitations and their potential interruption, and for the constraints of the different ‘sorts’ of utterance with respect to turn-taking: whether the TRP is free, or the speaker has selected someone to speak next, has encouraged anyone to speak, or has indicated the course of an extended multi-utterance turn at talk as in sentence beginnings like “first of all,” or “let me tell you something:. . . ”. The model and extensions are then comprehensively analysed through a series of large quantitative evaluations computing various aggregate statistics such as: the total times of single talk, multiple talk and silences; total occurrences of utterances, silences, simultaneous talk, multiple starts, middle-of-utterance attempts at talking, false-starts, abandoned utterances (interrupted by others), and more.
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Cheng, Lin. "Modelling airport passenger group dynamics using an agent-based method." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/72999/1/Lin_Cheng_Thesis.pdf.
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This thesis investigates the influence of passenger group dynamics on passengers' behaviour in an international airport. A simulation model is built to analyse passengers' behaviour during airport departure processes and during an emergency event. Results from the model showed that passengers' group dynamics have significant influences on the performance and utilisation of airport services. The agent-based model also provides a convenient way to investigate the effectiveness of space design and service allocations, which may contribute to the enhancement of passenger airport experiences.
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Nikolaishvili, George. "Investigation of the Equations Modelling Chemical Waves Using Lie Group Analysis." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3996.
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A system of nonlinear di fferential equations, namely, the Belousov-Zhabotinskii reaction model has been investigated for nonlinear self-adjointness using the recent work of Professor N.H.Ibragimov. It is shown that the model is not nonlinearly self-adjoint. The symmetries of the system and nonlinear conservation laws are calculated. The modi fied system, which is nonlinearly self-adjoint, is also analysed. Its symmetries and conservation laws are presented.
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Basiri, Mohammad Hossein. "Developments in computer modelling for the valuation of group mining companies." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326604.
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Carr, Catherine. "Modelling of intensive group music therapy for acute adult psychiatric inpatients." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/26966.
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Background: Acute inpatient stays are decreasing. Evidence for music therapy in mental healthcare exists but practice varies. Short admissions and therapy frequency (usually weekly), limit access, yet acceptability of increased frequency to patients is unknown. Research to model processes and outcomes of intensive provision may identify how best to provide for acute contexts informing clinical practice and future research. Methods: 114 patients admitted to hospital with acute mental health problems were recruited. Patients attended group music therapy 1-3 times per week during admission. Repeated measures assessing patient experiences, session appraisal, motivation and commitment were completed. Questionnaire thematic analysis identified important processes which were coded from session recordings. Multilevel modelling was used to examine associations between music therapy components, session appraisal, motivation, commitment and subsequent attendance. End of therapy interviews with 16 patients explored changes experienced and views on therapy frequency. Results: Attendance was 3 times greater for patients with 3 sessions per week. The majority found increased frequency acceptable and beneficial. Processes of engagement, emotional expression and social connection suggested active music-making, synchrony and singing to be important for group cohesion. Singing was significantly associated with appraisal and motivation. Musical initiation by group members was associated with motivation and commitment. All three outcomes were associated with each other, with session appraisal and increased frequency independently associated with subsequent attendance. Patient attributions for change included creativity, experiential learning and therapist directed reflective discussions. Conclusion: Intensive group music therapy is acceptable to the majority of patients, perceived as beneficial and increases access. Intensive provision is associated with greater engagement and positive experiences, which in turn, are associated with group commitment. Patient experiences can inform practice. Further research should examine effectiveness of intensive provision. Therapists should continue to prioritise engagement through active music-making and singing, and services consider implementation of intensive provision.
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Librovich, Bronislav. "Modelling of group combustion of droplets in a spray fuel cloud." Thesis, University of Central Lancashire, 1999. http://clok.uclan.ac.uk/19287/.
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Release and combustion of a spray cloud in an atmosphere is a phenomenon encountered in a wide range of applications. For solution of a set of problems which is connected with ecology, theory of combustion and explosion, engine design, fire safety, etc. the knowledge of spray combustion behaviour is required. To investigate the influence of a variety in density and transport coefficients and flame front structure, combustion of pure gas cloud is studied numerically. Combustion of a small-scale spherical pocket of fuel droplets in a calm environment may be considered as a model enabling the transient combustion process to be studied conveniently in one-dimensional geometry. Apart from pure academic interest, such a study provides useful estimations of burning spray cloud characteristics which can be applied for the analysis of more complicated situations. An analytical approach is used to find quasi-steady state distributions of gas temperature and fuel mass fraction for both pure evaporating and burning clouds. This approach is quite fruitful, it gives important qualitative analytical relationships, which help to comprehend the complex process of evaporation or combustion of spray the cloud. Numerical method is used to solve the problem of spray cloud combustion using more common unsteady statement. Two types of ignition are used at the centre or from penphery of cloud. Two types of flames (premixed and diffusion flames) are observed in the numerical simulations. Distributions of all components and temperature are obtained at different moments of time for both types of ignition. The diffusion burning time and total evaporation time are estimated using numerical results.
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Li, Fengfeng. "Multi-criteria optimization of group replacement schedules for distributed water pipeline assets." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/66195/1/Fengfeng_Li_Thesis.pdf.
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This thesis presents a multi-criteria optimisation study of group replacement schedules for water pipelines, which is a capital-intensive and service critical decision. A new mathematical model was developed, which minimises total replacement costs while maintaining a satisfactory level of services. The research outcomes are expected to enrich the body of knowledge of multi-criteria decision optimisation, where group scheduling is required. The model has the potential to optimise replacement planning for other types of linear asset networks resulting in bottom-line benefits for end users and communities. The results of a real case study show that the new model can effectively reduced the total costs and service interruptions.
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Danna, Kate. "Using Video Modelling and Video Self-Modelling to Teach a Group of Young Adults with Intellectual Disabilities to Make Point of Sales Electronic Transactions." Thesis, University of Canterbury. Education, 2015. http://hdl.handle.net/10092/10842.
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The ability to make purchases in community settings is highly advantageous as it allows individuals freedom of choice and the ability to function within their own community. Independence and autonomy is especially important for individuals with intellectual disabilities (ID’s), however prerequisite knowledge of money concepts required for making cash purchases may be too complex for individuals with cognitive challenges. The use of EFTPOS cards to make purchases is a comparatively easy process with limited prerequisite skills required therefore, is an ideal starting point for teaching purchasing skills to individuals with cognitive challenges. Video modelling (VM) and video self-modelling (VSM) procedures have shown to be
effective and efficient instructional techniques for teaching various skills to individuals with ID’s however, research on the effectiveness and efficiency of these procedures with individuals with Down syndrome (DS) or with EFTPOS purchases is minimal.
This study aimed to examine the effectiveness of VM and VSM interventions in teaching independent EFTPOS purchasing skills to 6 young adults with DS using a
non-concurrent within-participant design. The results indicates that both VM and VSM interventions were effective and efficient as all 6 participants exhibited
increases in task acquisition with the introduction of the intervention, and 5 of the 6 were able to consistently use their EFTPOS cards to purchase chosen items
throughout intervention and follow-up generalisation probes (2 weeks postintervention).
Therefore, this study suggests both VM and VSM may be equally effective for teaching young adults with DS EFTPOS purchasing skills in community
stores.
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Nicholls, Gareth Antony. "Modelling and kinetics of tetrabutylammonium benzoate-catalysed group transfer polymerisation of methyl methacrylate." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/27119.
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Group Transfer Polymerisation (GTP) is a silicon-mediated living polymerisation which can be performed over a wide range of temperatures, allows good control of molecular weight and is a good mechanism for production of block and graft copolymers. A silyl ketene acetal initiator is used to start polymerisation of acrylic or methacrylic monomers which are catalysed by nucleophilic or Lewis acid catalysts in a dry, impurity-free atmosphere. Since its discovery in 1983 by Du Pont, GTP has been ardently researched, although it has not yet been used in an industrial process due to the complicated processing involved and the high cost of initiators.
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Hattingh, Barend Burgert. "Product evaluation and reaction modelling for the devolatilization of large coal particles / Barend Burgert Hattingh." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8739.
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A fundamental understanding of the process of devolatilization requires extensive knowledge of
not only the intrinsic properties of the parent coal and its subsequent formed products (tars,
gases and chars), but also its characteristic reaction rate behaviour. Devolatilization behaviour
has been extensively addressed in literature with the use of powdered coal samples, which
normally do not adhere to particle size constraints of coal conversion processes utilizing lump
coal. The aim of this investigation was therefore to assess the devolatilization behaviour (with
respect to product yield and -quality; and reaction rate modelling) of four typical South African
coals (UMZ, INY, G#5 and TSH) confined to the large particle regime. All four coals were found
to be bituminous in rank, with vitrinite contents ranging between 24.4 vol.% and 69.2 vol.%
(mineral matter free basis). Two were inertinite-rich coals (UMZ and INY) and the other two
were vitrinite-rich coals (G#5 and TSH). From thermoplasticity measurements it was evident that
only coal TSH displayed extensive thermoplastic behaviour, while a comparison between
molecular properties confirmed the higher abundance of poly-condensed aromatic structures
(aromaticity of 81%) present in this coal.
Product evolution was evaluated under atmospheric conditions in a self-constructed, large
particle, fixed-bed reactor, on two particle sizes (5 mm and 20 mm) at two isothermal reactor
temperatures (450°C and 750°C) using a combination of both GC and MS techniques for gas
species measurement, while standard gravimetric methods were used to quantify tar- and char
yield respectively. Elucidation of tar- and char structural features involved the use of both
conventional- and advanced analytical techniques. From the results it could be concluded that
temperature was the dominating factor controlling product yield- and quality, with significant
increases in both volatile- and gas yield observed for an increase in temperature. Tar yields
ranged between 3.6 wt.% and 10.1 wt.% and increased in the order UMZ < INY < TSH < G#5,
with higher tar yields obtained for coal G#5, being ascribed to larger abundances of vitrinite and
liptinite present in this coal. For coal TSH, lower tar yields could mainly be attributed to the
higher aromaticity and extensive swelling nature of this coal. Evolved gases were found to be
mainly composed of H2, CH4, CO and CO2, low molecular weight olefins and paraffins; and
some C4 homologues. Advanced analytical techniques (NMR, SEC, GC-MS, XRD, etc.)
revealed the progressive increase of the aromatic nature of both tars and chars with increasing
temperature; as well as subsequent differences in tar composition between the different parent coals. In all cases, an increase in devolatilization temperature led to the evolution of larger
amounts of aromatic compounds such as alkyl-naphthalenes and PAHs, while significant
decreases in the amount of aliphatics and mixed compounds could be observed. From 13C
NMR, HRTEM and XRD carbon crystallite results it was clear that an increase in temperature
led to the formation of progressively larger, more aromatic and structurally orientated polycondensed
carbon structures.
Reaction rate studies involved the use of non-isothermal (5-40 K/min) and isothermal (350-
900°C) thermogravimetry of both powdered (-200 μm) and large particle samples (20 mm) in
order to assess intrinsic kinetics and large particle rate behaviour, respectively. Evaluation of
the intrinsic kinetic parameters of each coal involved the numerical regression of non-isothermal
rate data in MATLAB® 7.1.1 according to a pseudo-component modelling philosophy. Modelling
results indicated that the intrinsic devolatilization behaviour of each coal could be adequately
described by using a total number of eight pseudo-components, while reported activation
energies were found to range between 22.3 kJ/mol and 244.3 kJ/mol. Description of the rate of
large particle devolatilization involved the evaluation of a novel, comprehensive rate model
accounting for derived kinetics, heat and mass transport effects, as well as physical changes
due to particle swelling/shrinkage. Evaluation of the proposed model with the aid of the
COMSOL Multiphysics 4.3 simulation software provided a suitable fit to the experimental data of
all four coals, while simulation studies highlighted the relevant importance of not only the effect
of particle size, but also the importance of including terms affecting for heat losses due to
particle swelling/shrinkage, transport of volatile products through the porous char structure, heat
of reaction and heat of vaporization of water.Thesis (PhD (Chemical Engineering))--North-West University, Potchefstroom Campus, 2013
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Parker, David J. "Modelling nucleophilic substitution at main group elements by NMR spectroscopy and X-ray crystallography." Thesis, Open University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363493.
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Ward, Robert M. "Modelling of silicon-germanium alloy heterostructures using double group formulation of k . p theory." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9757.
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Silicon-Germanium alloy heterostructures offer the most viable opportunity to integrate electronics with optoelectronic devices for widespread commercial application. Indeed Germanium rich devices may be designed for application around 1.5 m by preying on the direct-gap energy of 890meV. Low power optical modulators operating, under the quantum confined Stark effect, at wavelength bands used in 3rd generation fibre optic communication channels are developed in this thesis from a theoretical perspective. An investigation into strained Germanium rich quantum well structures was performed, revealing information about sub-band dispersion, joint density of states and absorption coefficient using the double group formulation of k . p theory. Using zone centre eigenstates as symmetrised half integer basis functions transforming according to irreps of the double group, the spin orbit interaction is incorporated into the unperturbed Hamiltonian. Along with semi-empirical input parameters available in the literature, dispersion in bulk Silicon and Germanium reveals information about hole effective masses and indirect conduction band minima in broad agreement with experimental data. In accordance with degenerate perturbation theory; effective mass Hamiltonians, with an arbitrary quantisation axis through a canonical transformation, are constructed through a series of matrix multiplications. Retaining operator ordering allows numerical modelling of heterostructures grown on arbitrary growth planes with appropriate boundary conditions across an abrupt interface under the envelope function framework. In this thesis, the effect on the transition energy, hh1-e1, by the choice of growth plane in a quantum well heterostructure is investigated.
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Kuan, Kam-sing. "CoBlocks using objects to improve voxel modelling to support group work in early design phases /." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36212519.
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Kuan, Kam-sing, and 關錦盛. "CoBlocks: using objects to improve voxel modelling to support group work in early design phases." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36212519.
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Berthet, Jean-Claude CeÌdric. "Modelling of relaxation processes in polymers in the glassy state : methoxy group rotation in PVME." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418769.
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Calcraft, Paul Richard Thomas. "The evolution of group traits : modelling natural selection on trait prevalence within and between groups." Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/67214/.
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One of evolution's greatest innovations was group living; indeed, it is fundamental to our daily lives as humans. Yet despite intense theoretical and empirical work, the details of how group living arose and is maintained are poorly understood. A central question in this area concerns the strength of natural selection operating between groups of organisms (group selection) because some think this is key to the evolution of group behaviour. It is, however, challenging to measure natural selection occurring between groups and between the individuals within those groups simultaneously. Consequently, a number of contentious theoretical issues have plagued group selection research for a number of decades, and empirical work on this topic is often misinterpreted. In this thesis, I investigate three biological systems that are candidates for group selection where empirical data is readily available. Using techniques from theoretical and computational biology - simulations, game theory and population genetics - I model evolution occurring at multiple levels simultaneously (multi-level selection), shedding light on the evolution and maintenance of group traits. First, I consider the evolution of a trait - lateralization - at the population- and colony-level in eusocial organisms, which have a reproductive structure that promotes group organisation and cooperation. I provide an evolutionary explanation for the strength of lateralization in colonies of the red wood ant, Formica rufa, as a compromise between intraspecific and predatory interactions. After extending the analysis to involve predators targeting multiple colonies simultaneously, I show that populations should tend towards an equal distribution of left- and right- lateralized colonies, resulting in zero population-level lateralization. This contradicts the established view that sociality should produce strong levels of lateralization at the population level. Second, I study a sub-social spider, Anelosimus studiosus, which is a group-living species that has recently been claimed to exhibit group-level adaptation. I use evolutionary game theory to explain the evolution of colony aggression with individual costs and benefits, providing an alternative to the existing group-level interpretation. The model generates a striking fit to the data without any between-group interactions. Therefore, I conclude that more evidence is needed to infer group-level adaptation in this colonial spider. Third, I study the Solanaceae, a plant family whose breeding system is reported to have undergone species selection - group selection acting on whole species. I investigate the evolution of self-fertilization over the family's phylogenetic history. By integrating an existing phylogeny with models of breeding system evolution at the individual level, I find the average selection pressure - and attendant properties of populations - expected to have characterised the Solanaceae over ~36 million years. In conclusion, I have shown the power of modelling approaches to clarify evolutionary explanations, to question existing interpretations, and to identify experiments that can help researchers identify the true causes of trait evolution.
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Gilbert, Matthew G. "Group and societal decision making : an exploration of modelling paradigms applied to nuclear facility siting." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/95975/.
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This thesis has explored the area of group and societal decision making applied to nuclear facility siting problems, and some of the common modelling paradigms used to assist decision makers (either to enhance understanding or serving as a vehicle to compare potential alternatives). We have explored common issues and the history surrounding the construction of decision support systems, and identified potential modelling paradigms that could be used to assist decision makers in our facility siting setting. In the area of utilities, we investigate measuring the influence of some group members on others in decision making. Being better able to identify potentially influential behaviour would be useful in supporting and subsequently auditing a decision. A new measure of the influence of individuals is given, which is analogous to the well-known Cook’s distance used to identify influential data in regression. The theoretical properties of this measure are explored. A simple method to identify sub-groups within the group of decision makers is given. We investigate the efficiency of our new measures using large scale randomised studies. We use these measures to identify sub-groups of individuals with similar beliefs in a data set collected in a previous experiment. In the areas of system dynamics and discrete event simulation, we have constructed models of public response to the UK government’s request for volunteer communities to host a Geological Disposal Facility (GDF) for nuclear waste in the 2009-2013 siting process. We create models in each paradigm to explore the influential factors behind Cumbria’s withdrawal from the process in early 2013 based on opinion surveys during the 4 year public deliberation. We have considered the suitability of each paradigm as a modelling process for public response and deliberation, and explore whether the extension of the decision deadline requested by the councils could have biased the process. Our approach models the interactions between the 3 key stakeholder groups we included: the general public, the MRWS Partnership and Non-Governmental Organisations (NGOs). We show that a decision deadline extension may have biased the process. Additionally, we contrast the strengths and weaknesses of each model and paradigm both generally, and for our specific scenario through response analysis to a selection of alternative scenarios.
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Lartey, Nathaniel. "Differentials in unemployment duration across households in South Africa: A two-level modelling approach." University of the Western Cape, 2018. http://hdl.handle.net/11394/6783.
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Philosophiae Doctor - PhDThis study aimed to examine the structural changes affecting the duration of unemployment across households in South Africa. It made use of existing datasets from the Labour Force Survey produced by Statistics South Africa, covering a period of six years (2011-2016). Relations among demographic and household variables were explored to determine how they related to unemployment duration. On the basis of the relations identified, a predictive analysis of unemployment duration was attempted using two-level modelling. The results suggest a significant difference in the duration of unemployment, according to the individual socio-demographic characteristics and the household moderating variables. More specifically, the greatest share percentage of both men and women experiencing long-term unemployment were found within the age group 25-34 years. The study also found that the percentage share of Non-White population groups experiencing longer duration of unemployment was more than for the White population group. Another variable found to have great influence on the duration of unemployment was the individual’s previous work experience. Going beyond the individual’s socio-demographic characteristics to consider household variables. It was found that unemployed workers living in households headed by a female are more vulnerable to longer unemployment duration. The study found individuals living in smaller households displaying longer unemployment duration. Also, it was found that individuals living in less endowed households (households where no one or few people were in gainful employment) were more vulnerable to experiencing longer unemployment spells. The study concluded with some recommendations for employment policy and follow-up research.
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TRAVAGIN, GABRIELE. "Scrittura espressiva in adolescenza: Dalla meta-analisi ad un test sperimentale di un nuovo intervento di scrittura." Doctoral thesis, Università Cattolica del Sacro Cuore, 2012. http://hdl.handle.net/10280/1256.
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Il presente programma di ricerca approfondisce l’uso dell’Expressive Writing (EW) con gli adolescenti a partire da tre studi, organizzati in modo sequenziale. Lo Studio 1 indaga l’efficacia e i fattori di moderazione dell’EW con gli adolescenti tramite meta-analisi. In particolare, è stata eseguita una review quantitativa degli studi sull’EW con partecipanti in età adolescenziale, attraverso i seguenti passaggi: ricerca sistematica e codifica degli studi; calcolo degli effect size; analisi dei moderatori. Lo Studio 2 confronta sperimentalmente sugli adolescenti gli effetti a breve e lungo termine di due tipi di istruzioni di scrittura, una convenzionale (EW) e l’altra orientata cognitivamente (CEW), elaborata sulla base dei risultati della meta-analisi. Le analisi sono state finalizzate a testare gli effetti della modificazione delle consegne di scrittura sul funzionamento emotivo e sociale degli adolescenti. Lo Studio 3 consiste in un’analisi secondaria dello Studio 2 ed esplora l’esito dell’intervento in funzione delle traiettorie di cambiamento dei meccanismi cognitivi (“Self-distancing”) rilevati negli scritti, tramite Group-Based Trajectory Modeling. I risultati degli studi sono discussi in funzione delle loro implicazioni teoriche e pratiche.The present research program aims at evaluating the use of Expressive Writing (EW) with adolescents through three studies, organized in a progressive fashion. Study 1 investigates the efficacy and moderators of EW with adolescents through a meta-analysis. The study performed a quantitative review of the EW interventions with adolescent samples, according to the following steps: systematic literature search and coding of the studies; calculation of the effect size; analysis of the moderators. Study 2 experimentally compares the short- and long-term effects of the traditional writing condition (EW) to a cognitively-oriented EW condition (CEW) on a sample of adolescents. The analyses had the objective to test the effects of altering the writing instructions on social and emotional adjustment of participants. Study 3 consists in a secondary analysis of the written essays collected in Study 2 with the intent of examining the effects of the intervention as a function of the cognitive processes (“Self-distancing”) observed during the writing sessions by means of the Group-Based Trajectory Modeling. The findings are discussed on the basis of their theoretical and practical implications.
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TRAVAGIN, GABRIELE. "Scrittura espressiva in adolescenza: Dalla meta-analisi ad un test sperimentale di un nuovo intervento di scrittura." Doctoral thesis, Università Cattolica del Sacro Cuore, 2012. http://hdl.handle.net/10280/1256.
Full textAbstract:
Il presente programma di ricerca approfondisce l’uso dell’Expressive Writing (EW) con gli adolescenti a partire da tre studi, organizzati in modo sequenziale. Lo Studio 1 indaga l’efficacia e i fattori di moderazione dell’EW con gli adolescenti tramite meta-analisi. In particolare, è stata eseguita una review quantitativa degli studi sull’EW con partecipanti in età adolescenziale, attraverso i seguenti passaggi: ricerca sistematica e codifica degli studi; calcolo degli effect size; analisi dei moderatori. Lo Studio 2 confronta sperimentalmente sugli adolescenti gli effetti a breve e lungo termine di due tipi di istruzioni di scrittura, una convenzionale (EW) e l’altra orientata cognitivamente (CEW), elaborata sulla base dei risultati della meta-analisi. Le analisi sono state finalizzate a testare gli effetti della modificazione delle consegne di scrittura sul funzionamento emotivo e sociale degli adolescenti. Lo Studio 3 consiste in un’analisi secondaria dello Studio 2 ed esplora l’esito dell’intervento in funzione delle traiettorie di cambiamento dei meccanismi cognitivi (“Self-distancing”) rilevati negli scritti, tramite Group-Based Trajectory Modeling. I risultati degli studi sono discussi in funzione delle loro implicazioni teoriche e pratiche.The present research program aims at evaluating the use of Expressive Writing (EW) with adolescents through three studies, organized in a progressive fashion. Study 1 investigates the efficacy and moderators of EW with adolescents through a meta-analysis. The study performed a quantitative review of the EW interventions with adolescent samples, according to the following steps: systematic literature search and coding of the studies; calculation of the effect size; analysis of the moderators. Study 2 experimentally compares the short- and long-term effects of the traditional writing condition (EW) to a cognitively-oriented EW condition (CEW) on a sample of adolescents. The analyses had the objective to test the effects of altering the writing instructions on social and emotional adjustment of participants. Study 3 consists in a secondary analysis of the written essays collected in Study 2 with the intent of examining the effects of the intervention as a function of the cognitive processes (“Self-distancing”) observed during the writing sessions by means of the Group-Based Trajectory Modeling. The findings are discussed on the basis of their theoretical and practical implications.
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Groenewald, Suzanne Anél. "Reflector modelling of MTR cores making use of normalised generalised equivalence theory." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9054.
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This research focuses on modelling reflectors in typical material testing reactors (MTRs). Reflectors present some challenges to the usual approach to full-core calculational models. Diffusion theory is standardly used in full-core calculations and is known to be inaccurate in regions where the flux is anisotropic, for example within the reflectors. Thus, special consideration should be given to reflector models. In this research, normalised generalised equivalence theory is used to homogenise cross-sections and calculate equivalent nodal parameters and albedo boundary conditions for the reflector surrounding a typical MTR reactor. Various studies have shown that equivalence theory can be used to accurately generate equivalent nodal parameters for the core and reflector regions of large reactors, such as pressurised and boiling water reactors, in one dimension and for two neutron energy groups. This has not been tested for smaller reactors where leakage, environment sensitivity and multi-group spectrum dependency are much larger.
The SAFARI-1 MTR reactor is modelled in this work. A thirty day operational cycle is simulated for this reactor, using the nodal diffusion code MGRAC. NGET reflector equivalent nodal parameters are calculated using the codes NEWT and EQUIVA. The impact of different reflector models are evaluated, based on their effect on the core power, flux distribution, reactivity and neutron leakage over the duration of the operational cycle.
It is found that homogenisation introduces some environment dependencies in the reflector parameters, particularly in the corners of the reactor core. In full-core calculations, the reflector parameters show some sensitivity to the in-core reflector structures, but not the fuel composition. A practical reflector model for SAFARI-1 is proposed, which proves that NGET equivalence theory can be used for multi-group reflector modelling in a small MTR reactor. This approach to reflector modelling simplifies the core model, increases the accuracy of a diffusion calculation, and increases the efficiency (shorter calculational time and better convergence behaviour) of computer simulations.Thesis (MSc (Engineering Sciences in Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013.
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Martin, Lynne. "From conflict comes consensus : the influence of modelling feedback on processes of small group decision making." Thesis, University of Surrey, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308628.
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Ibrahim, Shire Mohammed. "Participatory system dynamics modelling approach to safe and efficient staffing level management within hospital pharmacies." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/34790.
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With increasingly complex safety-critical systems like healthcare being developed and managed, there is a need for a tool that allows us to understand their complexity, design better strategies and guide effective change. System dynamics (SD) has been widely used in modelling across a range of applications from socio-economic to engineering systems, but its potential has not yet been fully realised as a tool for understanding trade-off dynamics between safety and efficiency in healthcare. SD has the potential to provide balanced and trustworthy insights into strategic decision making. Participatory SD modelling and learning is particularly important in healthcare since problems in healthcare are difficult to comprehend due to complexity, involvement of multiple stakeholders in decision making and fragmented structure of delivery systems. Participatory SD modelling triangulates stakeholder expertise, data and simulation of implementation plans prior to attempting change. It provides decision-makers with an evaluation and learning tool to analyse impacts of changes and determine which input data is most likely to achieve desired outcomes. This thesis aims to examine the feasibility of applying participatory SD modelling approach to safe and efficient staffing level management within hospital pharmacies and to evaluate the utility and usability of participatory SD modelling approach as a learning method. A case study was conducted looking at trade-offs between dispensing backlog (efficiency) and dispensing errors (safety) in a hospital pharmacy dispensary in an English teaching hospital. A participatory modelling approach was employed where the stakeholders from the hospital pharmacy dispensary were engaged in developing an integrated qualitative conceptual model. The model was constructed using focus group sessions with 16 practitioners consisting of labelling and checking practitioners, the literature and hospital pharmacy databases. Based on the conceptual model, a formal quantitative simulation model was then developed using an SD simulation approach, allowing different scenarios and strategies to be identified and tested. Besides the baseline or business as usual scenario, two additional scenarios (hospital winter pressures and various staffing arrangements, interruptions and fatigue) identified by the pharmacist team were simulated and tested using a custom simulation platform (Forio: user-friendly GUI) to enable stakeholders to play out the likely consequences of the intervention scenarios. We carried out focus group-based survey of 21 participants working in the hospital pharmacy dispensaries to evaluate the applicability, utility and usability of how participatory SD enhanced group learning and building of shared vision for problems within the hospital dispensaries. Findings from the simulation illustrate the knock-on impact rework has on dispensing errors, which is often missing from the traditional linear model-based approaches. This potentially downward-spiral knock-on effect makes it more challenging to deal with demand variability, for example, due to hospital winter pressures. The results provide pharmacy management in-depth insights into potential downward-spiral knock-on effects of high workload and potential challenges in dealing with demand variability. Results and simulated scenarios reveal that it is better to have a fixed adequate staff number throughout the day to keep backlog and dispensing errors to a minimum than calling additional staff to combat growing backlog; and that whilst having a significant amount of trainees might be cost efficient, it has a detrimental effect on dispensing errors (safety) as number of rework done to correct the errors increases and contributes to the growing backlog. Finally, capacity depletion initiated by high workload (over 85% of total workload), even in short bursts, has a significant effect on the amount of rework. Evaluative feedback revealed that participatory SD modelling can help support consensus agreement, thus gaining a deeper understanding of the complex interactions in the systems they strive to manage. The model introduced an intervention to pharmacy management by changing their mental models on how hospital winter pressures, various staffing arrangements, interruptions and fatigue affect productivity and safety. Although the outcome of the process is the model as an artefact, we concluded that the main benefit is the significant mental model change on how hospital winter pressures, various staffing arrangements, interruptions and fatigue are interconnected, as derived from participants involvement and their interactions with the GUI scenarios. The research contributes to the advancement of participatory SD modelling approach within healthcare by evaluating its utility and usability as a learning method, which until recently, has been dominated by the linear reductionist approaches. Methodologically, this is one of the few studies to apply participatory SD approach as a modelling tool for understanding trade-offs dynamics between safety and efficiency in healthcare. Practically, this research provides stakeholders and managers, from pharmacists to managers the decision support tools in the form of a GUI-based platform showcasing the integrated conceptual and simulation model for staffing level management in hospital pharmacy.
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Schmidt, Eric. "Atomistic modelling of precipitation in Ni-base superalloys." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/275131.
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The presence of the ordered $\gamma^{\prime}$ phase ($\text{Ni}_{3}\text{Al}$) in Ni-base superalloys is fundamental to the performance of engineering components such as turbine disks and blades which operate at high temperatures and loads. Hence for these alloys it is important to optimize their microstructure and phase composition. This is typically done by varying their chemistry and heat treatment to achieve an appropriate balance between $\gamma^{\prime}$ content and other constituents such as carbides, borides, oxides and topologically close packed phases. In this work we have set out to investigate the onset of $\gamma^{\prime}$ ordering in Ni-Al single crystals and in Ni-Al bicrystals containing coincidence site lattice grain boundaries (GBs) and we do this at high temperatures, which are representative of typical heat treatment schedules including quenching and annealing. For this we use the atomistic simulation methods of molecular dynamics (MD) and density functional theory (DFT). In the first part of this work we develop robust Bayesian classifiers to identify the $\gamma^{\prime}$ phase in large scale simulation boxes at high temperatures around 1500 K. We observe significant \gamma^{\prime} ordering in the simulations in the form of clusters of $\gamma^{\prime}$-like ordered atoms embedded in a $\gamma$ host solid solution and this happens within 100 ns. Single crystals are found to exhibit the expected homogeneous ordering with slight indications of chemical composition change and a positive correlation between the Al concentration and the concentration of $\gamma^{\prime}$ phase. In general, the ordering is found to take place faster in systems with GBs and preferentially adjacent to the GBs. The sole exception to this is the $\Sigma3 \left(111\right)$ tilt GB, which is a coherent twin. An analysis of the ensemble and time lag average displacements of the GBs reveals mostly `anomalous diffusion' behaviour. Increasing the Al content from pure Ni to Ni 20 at.% Al was found to either consistently increase or decrease the mobility of the GB as seen from the changing slope of the time lag displacement average. The movement of the GB can then be characterized as either `super' or `sub-diffusive' and is interpreted in terms of diffusion induced grain boundary migration, which is posited as a possible precursor to the appearance of serrated edge grain boundaries. In the second part of this work we develop a method for the training of empirical interatomic potentials to capture more elements in the alloy system. We focus on the embedded atom method (EAM) and use the Ni-Al system as a test case. Recently, empirical potentials have been developed based on results from DFT which utilize energies and forces, but neglect the electron densities, which are also available. Noting the importance of electron densities, we propose a route to include them into the training of EAM-type potentials via Bayesian linear regression. Electron density models obtained for structures with a range of bonding types are shown to accurately reproduce the electron densities from DFT. Also, the resulting empirical potentials accurately reproduce DFT energies and forces of all the phases considered within the Ni-Al system. Properties not included in the training process, such as stacking fault energies, are sometimes not reproduced with the desired accuracy and the reasons for this are discussed. General regression issues, known to the machine learning community, are identified as the main difficulty facing further development of empirical potentials using this approach.
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Proudlove, Nathan Charles. "The support of group decision making using judgemental modelling : an exploration of the contribution of behavioural factors." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.631708.
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The dominant paradigms in the decision supporting disciplines of operational research (OR) and group decision support systems (GDSS) have a unitary and functionalist outlook, and believe they design group decision support processes that promote procedural rationality through reducing group process losses. Though potentially very valuable, insights from the behavioural sciences have not been much investigated by group decision support researchers. Past investigations into the effects of individual differences have produced ambiguous and contradictory results, probably as a result of using inappropriate theory and instruments. Issues of plurality of interests, power and conflict have not been given much consideration within the dominant paradigms. Also, despite imposing structured support processes on groups of decision makers, the effects of these support processes on group dynamics and group development have received very little attention. This thesis describes the use of multiattribute decision making (MADM) software, the Judgemental Analysis System (JAS), as part of a longitudinal group decision support process intended to help decision makers explore and develop preferences. Though all steps are not computer-supported, the process can be thought of as very similar in use and effect to a GDSS. Measures to indicate individual and group behaviours are derived from the MADM data. Multidimensional scaling is used to produce perceptual maps to explore and demonstrate these behaviours. The cognitive style of decision makers is assessed using the Kirton Adaption-Innovation Inventory (KAI), and interpersonal influence data collected using questionnaires. Changes in perceptions are found to decrease in magnitude over the course of the JAS process, suggesting that the decision makers are developing clearer perspectives on the problem. Group consensus is found to increase over the JAS process, particularly at the early stages. Investigations into this suggest that this may (in part) be a manifestation of 'Groupthink' and similar phenomena that lead members of groups to conform, avoiding dissent at the cost of reducing the quality of the process and its outcome. This suggests that more effort should be made in the support process to guard against such confounds to rationality. Group members perceived to be influential by the rest of the group are found to be affecting the perspectives of the group as whole. Before the implications for the decision support process can be determined, further research is required to investigate the grounds for this influence. The effects of interpersonal influence are not evident at the level of the behaviour of the individual decision makers. No relationships are found between behaviour and individual or group (aggregated) level cognitive style. This is an important finding and lends weight to arguments that the knowledge from the behavioural sciences concerning this aspect of individual difference need not be incorporated into the type of OR and GDSS studied here. However, this type of investigation leads to consideration of interpersonal (i.e. grouplevel) processes such as group development. The required deeper investigation into such pluralistic ideas from the behavioural sciences represents a major challenge for OR and GDSS, but one with potentially very fruitful results for the improved support of group decision making.
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Mriheel, Ibrahim Youssef. "Basin modelling of the Gabes-Tripoli basin and geology of the Farwah Group reservoirs, Western Offshore, Libya." Thesis, University of Manchester, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496686.
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The Gabes-Tripoli Basin (G-T Basin) is a Mesozoic-Cenozoic basin which was initiated as a result of widespread, late Triassic-Middle Jurassic extensional movements that developed over a broad zone of strain between the African and European plates. The basin formation is probably related to strike slip movement between the western Libyan Coastal Fault System and the north margin of the basin. The basin rifting phase of lithospheric extension lasted as much as 40my. The dominant driving mechanism of subsidence seems clearly to have been subsidence due to cooling following lithospheric thinning and the tectonic subsidence history shows that a simple stretching model successfully predicts the overall characteristics of the long-term patterns of the tectonic subsidence of the basin. The sedimentary succession in the G-T Basin ranges in age from Triassic-Recent. It comprises a 10 km-thick succession of pre-rift Early-Middle Triassic, nonmarine and marine clastics, syn-rift late Triassic-Middle Jurassic, predominantly shallow marine carbonates and evaporites and Middle Jurassic-Recent post-rift marine carbonates and clastics. The tectono-stratigraphic units comprise 19 sequences on the time scale of second order sequences. For most sequences and sequence boundaries, either an eustatic or tectonically enhanced origin can be established. The analysis of the basin-fill history of the G-T Basin from the Triassic until the Holocene reveals that the basin underwent development from a continental sedimentary basin located on Gondwana to an epicratonic rift basin. When extensional movement ceased (middle Middle Jurassic), the basin subsided thermally and developed as part of a passive continental margin on the north African plate margin. The variation of heat flow over the G-T Basin from higher values at the basin centre to lower values toward the southern and northern margins is consistent with the calculated amount of crustal attenuation. Hence, the proposed stretching model is considered as paramount to the understanding of basin evolution and hydrocarbon accumulation. The G-T Basin is a passive groundwater basin and thermal conduction is the dominant mechanism of heat transport. Heat flow values range from 50-65 mW/m , typical values for granitic basement and are characteristic of the passive margin nature or thermally subsided postrift basins. The geothermal gradient of the G-T Basin ranges from 32.5 0C/km. to 45 OC/km. The geothermal gradient map shows relatively high average regional gradient at the centre of the basin and a progressive decrease from the depocentre to the basin margins. The high geothermal gradient zone at the centre of the basin coincides roughly with the zones of maximum crustal thinning in the basin. The observed organic thermal maturity measurements in the G-T Basin indicate that the pre Middle Eocene sequences are at a mature to over mature stage. The Middle-Upper Eocene Tellil sequence has attained an early mature stage while locally the Oligocene-early Miocene is in maturation stage. The rest of the Tertiary sequence is immature. The depth variation to the modelled top of the oil maturity 0.7 Ro ranges from 2000-2400m in the G-T Basin. The calculated organic maturities indicate that the early Eocene-late Cretaceous sequences are either mature or over mature with respect to the oil window. The current depth to the top of the oil window ranges from 2000 to 2400m, and the base of the oil window ranges from 3000 to 3650m. Combined geohistory and basin modelling indicates that the main phase of hydrocarbon generation from the Farwah Group source began 22.5 to 5.0 Ma. and continues until present. A relatively late generation (approximately 30-50 my after deposition) is ascribed to the lack of high palaeoheat flow and moderate burial, which is consistent with passive margin nature and post-rift thermally subsiding basin. Time of oil generation varies widely from the depocentre to the northern and southern margins of the basin depending on the heat flow variations. Geochemical analysis and basin modelling have confirmed the source potentiality of the early Eocene-late Cretaceous sequences to generate and expel hydrocarbon in the study area. Hydrocarbon has been generated in a wide span of time from several proven late Cretaceous- Palaeogene organic rich sources. But none of the sequences younger than the early Eocene had the capability to expel out hydrocarbon in the basin. Hydrocarbon was generated from the Al Jurf and Farwah sources in the basin centre first and earlier than the basin margins by about 15my. Hydrocarbon generation commenced about 30my from the Al Jurf Formation and at 22.5my from the Farwah source in the basin centre. At the basin margins, however, it began to generate 15my later from both principal sources. Thus, the earlier generated hydrocarbon at the basin centre has been subjected to secondary thermal cracking and as a result, huge gas accumulations have been discovered at the central parts of the G-T Basin. The Jirani Dolomite was formed during relative fall in sea-level in middle Ypresian (early Eocene) times, in shallow, hypersaline lagoons on a restricted shallow shelf. Petrographic studies , show that dolornitization proceeded in three stages. Stage I involved penecontemporaneous/early diagenetic dolornitization under hypersaline seepage reflux conditions. Stage II dolornitization, mainly confined to the non-anhydritic facies, was probably formed in the mixing zone between meteoric and seawater, probably at shallow depths of burial. Stage III dolornitization, which is volumetrically unimportant occurred at depth in the late stage of basin evolution, causing some filling of mouldic and vuggy porosity by medium crystalline, saddle dolomite. Evidence of mixing zone dolornitization indicates that the Jirani Dolomite was exposed subaerially. Exposure of the deposits to flushing by meteoric waters explains the dissolution of large portions of the anhydrite from the non-anhydritic dolomite facies, and the development of excellent reservoir characters in this facies, which make it one of the most important reservoir rocks in the offshore region. The most common porosity includes intercrystal, vuggy and mouldic types. Porosity are of both predolornitization and syndolornitization origins but the later appears to be the most dominant. Hence, reservoir quality is largely controlled by fluid dynamics.
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Afordakos, Orestis G. "On exploring the communicative impact of facilitated modelling during strategic group decision making : an interaction analysis study." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/60133/.
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Well into the 21st century strategic decisions remain at the forefront of organisational managerial activity. The ever increasing complexity and uncertainty of the modern world dictates the need for effective strategic decision making. In the attempt to pool together the necessary capabilities strategic decisions in large organisations take place in group settings thus bringing at the forefront the role of group decision making. Group decision making is fundamentally a communicative activity riddled with the intricate processes of negotiation. With negotiation comes conflict with group participants’ differences over perspectives and worldviews being viewed as the fundamental cause of it. Not all conflict is destructive. Benefits are also to be reaped if conflict is managed effectively. A number of techniques and methods have emerged in the field of the Management Sciences and Information Systems that intent to alleviate the destructive and promote the productive aspects of conflict. One technique that follows a rational approach to decision making and incorporates strong elements of facilitation and qualitative modelling has been termed as Facilitated Modelling (FM). The key distinction between FM and other approaches is the use of qualitative models as transitional objects argued to enhance the effectiveness of group conflict management. In the past two decades numerous calls for evaluating the impact FM models may have on conflict have been made with little to no response. This thesis is an exploratory attempt to offer partial insights and inform these calls. The theoretical perspective of Adaptive Structuration Theory acted as the under-bed guiding this exploration. The exploration adopted a multiple case study approach as the methodological avenue for collecting data. Interaction data derived from three workshops, during which strategic decisions were made, have been micro-coded and analysed using both statistical as well as flexible mapping techniques. The results revealed complex relationships between the manner in which the model is appropriated and the resulting conflict management processes. Specifically, findings indicate that when models are appropriated they will reduce the ineffective conflict management behaviours. The concept of Model Appropriations Complexity (MAC) has been introduced as a moderating variable between the model appropriations and conflict management effectiveness with the findings supporting a positive relationship between MAC and effective conflict management. Additional preliminary analyses indicate prior FM-related experience of group participants as another potential explanatory variable for future research to explore.
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Shi, Jun-Mei, Ulrich Rohde, and Horst-Michael Prasser. "Validation of the multiple velocity multiple size group (CFX10.0 N x M MUSIG) model for polydispersed multiphase flows." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28031.
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To simulate dispersed two-phase flows CFD tools for predicting the local particle number density and the size distribution are required. These quantities do not only have a significant effect on rates of mixing, heterogeneous chemical reaction rates or interfacial heat and mass transfers, but also a direct relevance to the hydrodynamics of the total system, such as the flow pattern and flow regime. The Multiple Size Group (MUSIG) model available in the commercial codes CFX-4 and CFX-5 was developed for this purpose. Mathematically, this model is based on the population balance method and the two-fluid modeling approach. The dispersed phase is divided into N size classes. In order to reduce the computational cost, all size groups are assumed to share the same velocity field. This model allows to use a sufficient number of particle size groups required for the coalescence and breakup calculation. Nevertheless, the assumption also restricts its applicability to homogeneous dispersed flows. We refer to the CFX MUSIG model mentioned above as the homogeneous model, which fails to predict the correct phase distribution when heterogeneous particle motion becomes important. In many flows the non-drag forces play an essential role with respect to the bubble motion. Especially, the lift force acting on large deformed bubbles, which is dominated by the asymmetrical wake, has a direction opposite to the shear induced lift force on a small bubble. This bubble separation cannot be predicted by the homogeneous MUSIG model. In order to overcome this shortcoming we developed an efficient inhomogeneous MUSIG model in cooperation with ANSYS CFX. A novel multiple velocity multiple size group model, which incorporates the population balance equation into the multi-fluid modeling framework, was proposed. The validation of this new model is discussed in this report.
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Shi, Jun-Mei, Ulrich Rohde, and Horst-Michael Prasser. "Validation of the multiple velocity multiple size group (CFX10.0 N x M MUSIG) model for polydispersed multiphase flows." Forschungszentrum Dresden-Rossendorf, 2007. https://hzdr.qucosa.de/id/qucosa%3A21630.
Full textAbstract:
To simulate dispersed two-phase flows CFD tools for predicting the local particle number density and the size distribution are required. These quantities do not only have a significant effect on rates of mixing, heterogeneous chemical reaction rates or interfacial heat and mass transfers, but also a direct relevance to the hydrodynamics of the total system, such as the flow pattern and flow regime. The Multiple Size Group (MUSIG) model available in the commercial codes CFX-4 and CFX-5 was developed for this purpose. Mathematically, this model is based on the population balance method and the two-fluid modeling approach. The dispersed phase is divided into N size classes. In order to reduce the computational cost, all size groups are assumed to share the same velocity field. This model allows to use a sufficient number of particle size groups required for the coalescence and breakup calculation. Nevertheless, the assumption also restricts its applicability to homogeneous dispersed flows. We refer to the CFX MUSIG model mentioned above as the homogeneous model, which fails to predict the correct phase distribution when heterogeneous particle motion becomes important. In many flows the non-drag forces play an essential role with respect to the bubble motion. Especially, the lift force acting on large deformed bubbles, which is dominated by the asymmetrical wake, has a direction opposite to the shear induced lift force on a small bubble. This bubble separation cannot be predicted by the homogeneous MUSIG model. In order to overcome this shortcoming we developed an efficient inhomogeneous MUSIG model in cooperation with ANSYS CFX. A novel multiple velocity multiple size group model, which incorporates the population balance equation into the multi-fluid modeling framework, was proposed. The validation of this new model is discussed in this report.
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Black, Elizabeth Ann. "Good Issues and bad tidying: what GitHub can tell us about agency in project-based group modelling work for higher education." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29571.
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Collaborative project work in technology-enabled environments at university is essential for learners to become ready for an increasingly global, complex, and virtualised workplace. Research on effective pedagogical and technical design for computer supported collaborative learning in higher education (CSCL) has often taken place in synchronous contexts, using specialised technology platforms. However, large-scale changes to work and education resulting from the COVID-19 pandemic necessitate the development of pedagogical and research approaches that support students working asynchronously, in distributed teams, using collaboration platforms that extend beyond institutional infrastructure.
Within the field of CSCL, knowledge building research has shown collaboration to be a complex systems phenomenon, involving the intersection of individual and collective efforts to actively advance the group’s shared knowledge, but studies analysing interaction data have been resource-intensive to conduct. Contemporary workplace platforms such as professional knowledge environments have multiple design affordances consistent with knowledge building principles, as well as the capacity to generate rich data about user activity. However, we have little understanding to date as to how these environments can support knowledge building pedagogies and facilitate associated research.
This study uses a case study approach and thematic analysis to investigate the activity of three university groups engaged in a collaborative modelling task over time. It investigates how agency emerges during project work in professional knowledge environments, and how the system interaction data can extend our understanding of effective collaboration processes. The results show that the GitHub platform can support knowledge building pedagogical designs in facilitating individual and collective agency in higher education group work, and provide insights into epistemic, regulative and relational aspects of learner behaviour at individual and group levels.
These findings extend our understanding of effective learning design to novel environments of a type likely to be used by our students in the workplace, and make design and methodological contributions to research on computer-supported collaborative learning.
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Burley, Stuart Donald. "Diagenetic modelling in the Triassic Sherwood sandstone group of England and its offshore equivalents, United Kingdom continental shelf." Thesis, University of Hull, 1987. http://hydra.hull.ac.uk/resources/hull:3155.
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Amoruso, Nicola. "Renormalization group flows between non-unitary conformal models." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11308/.
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Recentemente sono stati valutati come fisicamente consistenti diversi modelli non-hermitiani sia in meccanica quantistica che in teoria dei campi. La classe dei modelli pseudo-hermitiani, infatti, si adatta ad essere usata per la descrizione di sistemi fisici dal momento che, attraverso un opportuno operatore metrico, risulta possibile ristabilire una struttura hermitiana ed unitaria. I sistemi PT-simmetrici, poi, sono una categoria particolarmente studiata in letteratura. Gli esempi riportati sembrano suggerire che anche le cosiddette teorie conformi non-unitarie appartengano alla categoria dei modelli PT-simmetrici, e possano pertanto adattarsi alla descrizione di fenomeni fisici. In particolare, si tenta qui la costruzione di determinate lagrangiane Ginzburg-Landau per alcuni modelli minimali non-unitari, sulla base delle identificazioni esistenti per quanto riguarda i modelli minimali unitari. Infine, si suggerisce di estendere il dominio del noto teorema c alla classe delle teorie di campo PT-simmetriche, e si propongono alcune linee per una possibile dimostrazione dell'ipotizzato teorema c_{eff}.
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NIMNUAL, SOMKID. "APPLICATION OF MULTI-GROUP DIFFUSION THEORY TO MECHANISTIC MODELLING OF LEACHING BEHAVIOR OF SOLIDIFIED LOW-LEVEL RADIOACTIVE WASTE FORMS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184088.
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The application of multi-concentration group mathematical modelling to the leaching of radionuclide waste-forms which have continuous porous matrix such as cemented waste form is described. The modelling is illustrated analysing a hypothetical of some transport mechanisms such as molecular diffusion, ionic migration and convective flow for release of interest radionuclide from a solidified waste form which contains discrete particles of radioactive Sr-85 nuclides into the aqueous environment. The group parameters are derived from the classical electrochemistry concept of ion transport in dilute electrolytic solution. The numerical analysis is based on the Crank-Nicolson Implicit Methods which assures the stability of the solution at a practical time step. The results show that, for a short-time period of leaching in demineralized water the leaching behavior follows the predominating diffusion mechanism. After this point, the role of other processes apparent and continue until all radionuclides in the cement waste are leached out when compared to the Semi-Infinite Diffusion model which is based on pure diffusion mechanism. The multi-concentration group model can also be applied to long-term prediction of complicated release mechanisms of the radionuclides in the waste form of a particular disposal environment, unless the variables of interest such as the corrosion rate, the chemical reaction, erosion rate and etc. are determined by experiment or theoretical hypothesis. The appropriate differential equation then can be solved by the same general numerical approach. Also, the results of the modelling indicate which parameters should be measured experimentally in order to provide a quantitative test of the hypothetical release mechanism.
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Fava, Martina <1992>. "I modelli di Business nel settore della moda: il caso Benetton group s.r.l." Master's Degree Thesis, Università Ca' Foscari Venezia, 2019. http://hdl.handle.net/10579/15242.
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L'elaborato vuole illustrare le peculiarità del settore moda proponendo alcuni dati sull'odierna situazione dei mercati italiani ed internazionali. Infine, si fornisce una panoramica in merito al ruolo centrale assunto dai modelli di business adottati nel settore preso in esame, analizzando il caso dell'azienda Benetton group s.r.l.
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Norberg, Johan. "Demand Response In The Engineering Industry." Thesis, KTH, Elkraftteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202375.
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The power utilities in Sweden are planning to replace the major part of thenuclear power plants with renewable energy resource by the year 2030. Some ofthe renewable energy resources are intermittent, which may endanger the powersystem stability. A solution to this problem could be increased exibility in theend-users consumption, which is known as demand response. This is a usefultool that can be used to facilitate the large integration of renewable energyresource into the power grid. Therefore, several of the Swedish governmentauthorities have stated that the possibilities for demand response should befurther investigated.During this thesis, a case study is carried out at Volvo Group Truck OperationsPowertrain Productions in Koping, with the purpose of deriving theirtechnical possibilities for DR in the factory. Volvo in Koping mainly producesgearboxes to all trucks within the Volvo Group concern and belongs to the engineeringindustry sector. The engineering industry has previously not beeninvestigated for DR purposes in Sweden. The main goal of the thesis is to derivethe DR capacity of the factory and the associated time parameters. Onlydemand response by shifting the production in time is considered.One production group (Midiblock 2) in the factory is modelled using MixedInteger Linear Programming and the optimization problem is used to minimizethe electricity cost while fullling the production requirements. The optimizationproblem is done on daily basis and the result is binary operating pointsfor CNC-machines. The output from the Mixed Integer Linear Programmingproblem is sent to a discrete event model, which is used to validate the resultsand display the optimal energy consumption.The simulation results indicates that the modelled production group can performa load shift of 270 kWh/h during 4 hours by scheduling production. Duringthe reduction it should be possible to perform actions such as maintenance andchanging settings of machines. If the results are true for the entire factory, theresulting load reduction is 1.35 MWh/h during 4 hours. However, the nancialincentives to perform load reductions are low. Also, Volvo in Koping does nothave any routines to shut-o the CNC-machines and an extensive work is requiredto make a load reduction possible. Resulting in that DR at the factory isat the moment unrealistic. In addition to the possibilities for DR, the possibleeconomic savings by shutting o the CNC-machines when they are not producingunits are also approximated. Volvo in Koping can save a large amount ofenergy and yearly cut the cost by at least 5 000 000 SEK on these actions, whichis also the rst step towards enabling DR in the factory.Elkraftsbolagen i Sverige planerar att ersätta kärnkraftverken med förnybaraenergikällor fram till och med år 2030. Några av de förnybara energikällornaär intermittenta i sin produktion och kan på grund av detta medföra en faraför stabilitet i kraftsystemet. En del av lösningen till detta problem kan varaefterfrågeflexibiltet, vilket innebär att el-användarna är mer flexibla i förbrukningenoch anpassar sig till viss del efter kraftsystemets tillstånd. Efterfrågeflexibiltetär ett användbart verktyg som kan underlätta integreringen av de förnybaraenergikällorna. På grund av detta har era svenska statliga företag sagtatt er undersökning bör genomföras inom området efterfrågeflexibiltet.Under detta arbeta har en fallstudie utförts hos Volvo Group Truck OperationPowertrain Production i Köping. Syftet av fallstudien har varit attundersöka möjligheterna för efterfrågeflexibilitet i fabriken. Volvo i Köping producerartill största dels växellådor till samtliga lastbilar inom Volvo Group koncernenoch de tillhör därför industrisektorn verkstadsindustrier.En produktionsgrupp i fabriken modelleras med hjälp av linjärprogrammeringoch modellen används för att för att minimera elkostnaderna genom att föryttalast i tid och samtidigt uppfylla produktionskraven. Optimeringsproblemetberäknas med elpriser för ett dygn och resultatet av problemet är binära tillståndför CNC-maskinerna i produktionsgruppen. De binära tillstånden skickas tillen diskret modell i Matlab som används för att verifiera produktionskraven ochvisa den resulterande energiförbrukningen för produktionsgruppen.Resultatet visar att det är teoretiskt möjligt att förytta 270 kWh/h underen period på 4 timmar genom att förskjuta produktion i tid. Under produktionsstoppenär det möjligt att genomföra underhåll och att förändring iinställningarna på CNC-maskinerna. Om resultaten skalas upp till hela fabrikenskulle den resulterande lastförflyttningen vara 1.35 MWh/h under 4 timmar.Dock så är de ekonomiska incitamenten låga och lastföryttningen är inteekonomiskt hållbar. Ett ytterligare problem är att Volvo i Köping förtillfälletinte har några rutiner för att stänga av maskinerna. Därför krävs det ett omfattandearbete innan det skulle vara möjligt att genomföra en lastförflyttning.Efterfrågeflexibiltet hos Volvo i Köping är därför orealistiskt. Utöver att undersöka möjligheterna för efterfrågeflexibiltet i fabriken, har en del av arbetetsom mål att undersöka de möjliga energi- och kostnadsbesparingar som skapasav att stänga av CNC-maskinerna när de inte producerar enheter. Arbetet harvisat att Volvo i Köping kan varje är spara 5 000 000 SEK på att stänga avmaskinerna, vilket också är ett första steg mot efterfrågeflexibilitet i fabriken.
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Rawat, Rakesh. "User behaviour modelling in a multi-dimensional environment for personalization and recommendation." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/48135/1/Rakesh_Rawat_Thesis.pdf.
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Handling information overload online, from the user's point of view is a big challenge, especially when the number of websites is growing rapidly due to growth in e-commerce and other related activities. Personalization based on user needs is the key to solving the problem of information overload. Personalization methods help in identifying relevant information, which may be liked by a user. User profile and object profile are the important elements of a personalization system. When creating user and object profiles, most of the existing methods adopt two-dimensional similarity methods based on vector or matrix models in order to find inter-user and inter-object similarity. Moreover, for recommending similar objects to users, personalization systems use the users-users, items-items and users-items similarity measures. In most cases similarity measures such as Euclidian, Manhattan, cosine and many others based on vector or matrix methods are used to find the similarities. Web logs are high-dimensional datasets, consisting of multiple users, multiple searches with many attributes to each. Two-dimensional data analysis methods may often overlook latent relationships that may exist between users and items. In contrast to other studies, this thesis utilises tensors, the high-dimensional data models, to build user and object profiles and to find the inter-relationships between users-users and users-items. To create an improved personalized Web system, this thesis proposes to build three types of profiles: individual user, group users and object profiles utilising decomposition factors of tensor data models. A hybrid recommendation approach utilising group profiles (forming the basis of a collaborative filtering method) and object profiles (forming the basis of a content-based method) in conjunction with individual user profiles (forming the basis of a model based approach) is proposed for making effective recommendations. A tensor-based clustering method is proposed that utilises the outcomes of popular tensor decomposition techniques such as PARAFAC, Tucker and HOSVD to group similar instances. An individual user profile, showing the user's highest interest, is represented by the top dimension values, extracted from the component matrix obtained after tensor decomposition. A group profile, showing similar users and their highest interest, is built by clustering similar users based on tensor decomposed values. A group profile is represented by the top association rules (containing various unique object combinations) that are derived from the searches made by the users of the cluster. An object profile is created to represent similar objects clustered on the basis of their similarity of features. Depending on the category of a user (known, anonymous or frequent visitor to the website), any of the profiles or their combinations is used for making personalized recommendations. A ranking algorithm is also proposed that utilizes the personalized information to order and rank the recommendations. The proposed methodology is evaluated on data collected from a real life car website. Empirical analysis confirms the effectiveness of recommendations made by the proposed approach over other collaborative filtering and content-based recommendation approaches based on two-dimensional data analysis methods.
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Eng, Ngiang Jiang. "When 'trust in top management' matters to organisational performance and effectiveness: the impact of senior manager role-modelling and group cohesiveness." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/2229.
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While ‘trust in top management’ matters to organisational performance and effectiveness, low trust in top management remains an issue in many organisations despite their efforts in building trust. The persistence of such problems appears to be largely due to improper approach used in the treatments of trust. While the literature reflects a fair amount of effort directed towards an understanding of trust building process, little research, if any, has been done into three important issues that follow. First, the potential effects of group processes on employee perceptions of management’s trustworthiness. Second, the moderating effects of potential moderators on the relationships between trust in management and important organisational outcomes. Third, the potential impacts of cultural differences on trusting relationships.This research investigates into how organisations can strategise to deal with the persistent problem of low trust in top management. Backed by research evidence, the study provides insights for organisations to deal with this problem through (1) promoting group cohesiveness to improve employee trust in top management; and (2) promoting senior manager role-modelling to minimize the impacts of trust in top management on organisational outcomes.To carry out the research, this study develops a theoretical framework that includes group cohesiveness, top management’s trustworthiness factors, trust in top management, important organisational outcomes (i.e., affective commitment, job satisfaction, turnover intention, and intention-to-return), senior manager role-modelling, and their proposed interrelationships. From the theoretical framework emerges an analytical model which elucidates the theories and empirical evidence underlying the proposed relationships in the theoretical framework, and develops a series of theoretically justified and testable hypotheses to address the research questions/problem.Data collection was administered in two field studies conducted in WesternAustralia (the WA study) and Singapore (the SIN study). In both field studies, the population of interest was employees from a diverse range of industries. Thesampling frame for the WA study comprised ten (10) randomly selected companiesoperating in various industries; and a random sample of employees in a variety ofindustries. For the SIN study, the sampling frame included fifteen (15) randomlyselected companies operating in various industries. Of the 1,500 survey packsdistributed in the WA study, the hypotheses were empirically tested on a final sampleof 305 respondents using multiple regression analysis, simple regression analysis,and subgroup analysis. And, of the 1,000 survey packs distributed in the SIN study,the hypotheses were empirically tested on a final sample of 212 respondents using the same data analysis techniques.Evidence from both the WA and SIN studies consistently concludes, inter alia, that (1) group cohesiveness positively influences employee perceptions of top management’s trustworthiness, which in turn improve trust in top management; and (2) in situations where trust in top management is low, senior manager role-modelling can serve to minimize the impacts that trust in top management has on organisational outcomes, thereby minimizing undesirable impacts on organisational performance and effectiveness. Since the research findings have been replicable across two culturally different countries, their generalisability to other settings is highly possible.Further, the research findings offer several theoretical implications. First, referent of trust (trustee) moderates the trust–antecedent relationships, such that the trust model with two predictors (trustee’s ability, and integrity) is statistically desired for predicting trust in top management, whereas the trust model with three predictors (trustee’s ability, integrity, and benevolence) may be well-suited for predicting trust in other organisational authorities. Second, social context for trust (e.g., groups), in which group processes play a major role in the social construction of trust, must not be neglected in the study of trust. Third, at any level of trust in top management, senior manager role-modelling can serve to improve the levels of desirable outcomes, which in turn enhance desirable impacts on organisational performance and effectiveness. Fourth, study of trust should increase emphasis on potential moderator variables in trust–outcome relationships to enhance accuracy of research findings. Likewise, study of organisational performance and effectiveness should not neglect potential moderator variables that can possibly minimize the strong impacts that trust in top management has on important organisational outcomes, especially for situations with low trust in top management.Fifth, the regression models of trust in top management across culturally different countries may differ significantly due to the differences in valuing top management’s integrity when making judgments about top management’s trustworthiness. Sixth, positive influence of group cohesiveness on employee perceptions of top management’s trustworthiness may not be affected by cross cultural differences. Last but not least, cross cultural differences may not affect the impacts of trust in top management on affective commitment, turnover intention, and intention-to-return. However, they may vary the impacts that trust in top management has on job satisfaction due to the differences in valuing trust in top management when evaluating job experiences or work context.Equally important, the research findings suggest two practical implications. First, considering trust is both an interpersonal and a collective phenomenon, promoting group cohesiveness is important and instrumental in improving trust in top management. In this regard, firms can build group cohesiveness by ways of team building activities, management actions, and use of cohesion messages. Next, when appropriate senior manager role-modelling is lacking, trust in top management is very critical, and is required if high levels of affective commitment, job satisfaction, intention-to-stay, and intention-to-return are to be attained. However, when appropriate senior manager role-modelling exists, trust in top management becomes less critical in terms of affective commitment, job satisfaction, intention-to-stay, and intention-to-return. Some helpful steps for firms to promote senior manager role-modelling include: (1) top management formalizes an organisational value system that is consistent with the organisation’s goals and objectives; (2) top management internalizes the organisational value system as part of senior managers’ character, with role-modelling expert’s guidance; and (3) senior managers ‘role model’ the organisational value system for subordinates, provide an example of exemplary behaviour for subordinates to imitate, and thereby instilling the organisational value system into subordinates such that shared values are internalized in them.
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Tomassoni, Alberto. "Analisi ed implementazione di modelli per la previsione della domanda: il caso SCM Group S.p.a." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amslaurea.unibo.it/1698/.
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Alhazami, Mai. "ASSOCIATION BETWEEN WARFARIN ADHERENCE TRAJECTORIES, HOSPITALIZATION RISK, AND HEALTHCARE UTILIZATION AMONG MEDICARE PATIENTS WITH ATRIAL FIBRILLATION: A GROUP-BASED TRAJECTORY MODELLING APPROACH." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5561.
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Introduction: Warfarin is the most commonly prescribed drug for stroke prevention among Atrial Fibrillation (AF) patients, especially in older adult populations, but medication nonadherence reduces its effectiveness in clinical practice. Group Based Trajectory Models (GBTM) have been used to identify distinct patterns of adherence behavior related to various medications and understand the patient characteristics associated with each trajectory. The objectives of the study were: 1) Describe trajectories of warfarin adherence among Medicare AF patients, 2) Assess impact of adherence trajectories on AF-related hospitalization, 3) Estimate the AF-related direct costs for each adherence trajectory group.
Methods: We identified elderly AF patients initiating warfarin treatment during 2008-2010 using data from a random sample of Medicare beneficiaries. The study’s first aim is to classify patients into different trajectory groups based on their monthly adherence patterns using a Group-Based Trajectory Model (GBTM). A multinomial regression model was used to assess associations between baseline characteristics and adherence trajectories. The second aim is to evaluate the association between adherence trajectories and time to first hospitalization related to stroke or bleeding event. Hospitalization events due to bleeding or stroke were identified using corresponding ICD-9 codes, and a Cox proportional hazard model was performed. The third aim of the study is to calculate AF-related direct medical costs associated with each trajectory group. SASv9.4 was used for analysis.
Results: Among 3,246 beneficiaries who met inclusion criteria, six adherence trajectories were identified: 1) rapid-decline non-adherence group (11.5%), 2) moderate non-adherence group (24%), 3) rapid-decline then increasing adherence group (6.8%), 4) moderate-decline non-adherence group (8.2%), 5) slow-decline non-adherence group (24.3%), and 6) perfect adherence group (25.3%). Even though no statistical significances were found in the hazard of hospitalization among the adherence groups, there were higher odds of hospitalization among the lower adherence groups compared to perfect adherence group. Outpatient and monitoring costs were significantly higher in the lower adherence trajectories compared to perfect adherence group.
Conclusion:The GBTM is considered an innovative methodological approach that can be applied to longitudinal medication adherence data and account for the dynamic nature of adherence behavior in a better way than traditional adherence measures.
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Conti, Claudio. "Small-scale physical modelling of piled foundations for offshore wind turbines application." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Nowadays, finding alternative energy sources is becoming more and more important. Europe is particularly focusing on wind energy and in offshore wind energy especially. An issue concerning offshore wind energy which is gaining more and more attention is the noise emissions due to impact driven pile foundation. The noise caused by the installation process has been judged as “potentially dangerous for marine fauna” from the German Authorities.
This research thesis is part of a project which examines a viable alternative installation method for the displacement of pile foundations for offshore wind energy called pile jacking. This technology should be developed to be cost-efficient, flexibly scalable and to produce considerably reduced vibration and air pollution emissions during its placement in the sea bed. Jacked piles technology would eliminate almost any noise deriving from the hammer impact.
As most offshore piled foundations have been installed by impact driving technology, the question arises as to how piles with different the stiffness and the capacity , can otherwise be installed.
In order to delineate the significant variables affecting the load-bearing capacity and especially the ultimate uplift capacity of a pile in saturated sand, a small-scale test campaign in scale 1:30 has been performed at the Test Center for Support Structures in Hanover. The campaign was supervised by the Department for Support Structures of Fraunhofer IWES. A testing schedule comprising of 15 small-scale geotechnical physical experiments was conducted on open-ended piles to an embedded length of 75 cm using two method of pile installation: static jacking and impact driving.
The aim of this thesis is to obtain preliminary experimental data and set out the main features of this technology.
The results obtained by this study reveal that static jacking installation lead to higher resistances and is overall beneficial to the mechanical load bearing behavior of pile foundations.
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Holzbock, Matthias. "Mobile multimedia service provisioning with collective terminals in broadband satellite networks : an approach for systematic satellite communication system design for service provisioning to collective mobile terminals, including mobile satellite channel modelling, antenna pointing, hierarchical multi-service dimensioning and aeronautical system dimensioning." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5657.
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This work deals with provisioning of communication services via satellites for collectively mobile user groups in a heterogeneous network with several radio access technologies. The extended use of personalised user equipment beyond the coverage of one single terrestrial network by means of a satellite transport link, represents an increasingly important trend in mobile satellite communication. This trend is confirmed by the commercial introduction of broadband satellite communication to mobile terminals mounted on vehicles, trains, ships or aircraft. This work provides a consequent and structured approach for provisioning of services to broadband satellite terminals for mobile user groups and addresses: -- a systematic satellite communication system design process for collective mobile terminals; -- mobile satellite modelling at a wide range of frequencies, including current and potential frequencies; -- an optimised Pointing Acquisition and Tracking (PAT) system design including characterisation of moments for vehicle types of all mobile scenarios; -- a general hierarchical multi-service dimensioning methodology for collectively mobile user groups, including voice, data, and multimedia services; -- an aeronautical system dimensioning scheme with (capacity and handover) requirements analysis and evaluation of results for different satellite scenarios.
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Shekarifard, Ali. "Evaluation of petroleum generation potential and thermal maturity of the Shemshak Group in the Alborz Basin using organic petrography, geochemistry and basin modelling." Paris 6, 2009. http://www.theses.fr/2009PA066108.
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