This study aims to identify the challenges and opportunities of a small challenger company in a rigid and conservative high technology life science market. Strategies for finding a foothold, establish a position and creating a viable company is discussed. Qualitative and quantitative data was collected through interviews, online survey and conjoint analysis which were used as market research tools. For an entrepreneurial firm in the life science market it is important to tend to their most valuable resource, the employees, and it is vital that they have an extensive knowledge of the market that they are active in. Strategic planning tools and templates aid in executing and implementing the proposed business model. Recommendations for a model case entrepreneurial company regarding continued market research, increasing sales and strategies for marketing are made. Included in the thesis is also a discussion of wall effects in HPLC and ways to counteract them.

<p>Numerical simulations have been done with the CHEMKINsoftware to study different aspects of wall effects in thecombustion of lean, laminar and premixed flames in anaxisymmetric boundary-layer flow.</p><p>The importance of the chemical wall effects compared to thethermal wall effects caused by the development of the thermaland velocity boundary layer has been investigated in thereaction zone by using different wall boundary conditions, walltemperatures and fuel/air ratios. Surface mechanisms include acatalytic surface (Platinum), a surface that promotesrecombination of active intermediates and a completely inertwall with no species and reactions as the simplest possibleboundary condition.</p><p>When hydrogen is the model fuel, the analysis of the resultsshow that for atmospheric pressure and a wall temperature of600 K, the surface chemistry gives significant wall effects atthe richer combustion case (f=0.5), while the thermal andvelocity boundary layer gives rather small effects. For theleaner combustion case (f=0.1) the thermal and velocityboundary layer gives more significant wall effects, whilesurface chemistry gives less significant wall effects comparedto the other case.</p><p>For methane as model fuel, the thermal and velocity boundarylayer gives significant wall effects at the lower walltemperature (600 K), while surface chemistry gives rather smalleffects. The wall can then be modelled as chemically inert forthe lean mixtures used (f=0.2 and 0.4). For the higher walltemperature (1200 K) the surface chemistry gives significantwall effects.</p><p>For both model fuels, the catalytic wall unexpectedlyretards homogeneous combustion of the fuel more than the wallthat acts like a sink for active intermediates. This is due toproduct inhibition by catalytic combustion. For hydrogen thisoccurs at atmospheric pressure, but for methane only at thehigher wall temperature (1200 K) and the higher pressure (10atm).</p><p>As expected, the overall wall effects (i.e. a lowerconversion) were more pronounced for the leaner fuel-air ratiosand at the lower wall temperatures.</p><p>To estimate a possible discrepancy in flame position as aresult of neglecting the axial diffusion in the boundary layerassumption, calculations have been performed with PREMIX, alsoa part of the CHEMKIN software. With PREMIX, where axialdiffusion is considered, steady, laminar, one-dimensionalpremixed flames can be modelled. Results obtained with the sameinitial conditions as in the boundary layer calculations showthat for the richer mixtures at atmospheric pressure the axialdiffusion generally has a strong impact on the flame position,but in the other cases the axial diffusion may beneglected.</p><p><strong>Keywords:</strong>wall effects, laminar premixed flames,platinum surfaces, boundary layer flow</p> / QC 20100504

No description available.

This thesis describes an investigation of the velocity field in a fluid around a solid sphere undergoing transient motion parallel to, and midway between, two plane walls. Particle Image Velocimetry (PIV) was used to measure the velocity at many discrete locations in a plane that was perpendicular to the walls and included the centre of the sphere. The transient motion was achieved by releasing the sphere from rest and allowing it to accelerate to terminal velocity. <p>To avoid complex wake structures, the terminal Reynolds number was kept below 200. Using solutions of glycerol and water, two different fluids were tested. The first fluid was 100%wt glycerol, giving a terminal Reynolds number of 0.6 which represents creeping flow. The second solution was 80%wt glycerol yielding a terminal Reynolds number of 72. For each of these fluids, three wall spacings were examined giving wall spacing to sphere diameter ratios of h/d = 1.2, 1.5 and 6.0. Velocity field measurements were obtained at five locations along the transient in each case. Using Y to denote the distance the sphere has fallen from rest, velocity fields were obtained at Y/d = 0.105, 0.262, 0.524, 1.05, and 3.15. <p>It was observed that the proximity of the walls tends to retard the motion of the sphere. A simple empirical correlation was fit to the observed sphere velocities in each case. A wall correction factor was used on the quasi-steady drag term in order to make the predicted unbounded terminal velocity match the observed terminal velocity when the walls had an effect. While it has been previously established that the velocity of a sphere is retarded by the proximity of walls, the current research examined the link between the motion of the sphere and the dynamics of the fluid that surrounds it. By examining the velocity profile between the surface of the sphere at the equator and the wall, it was noticed that the shear stresses acting on the sphere increase throughout the transient, and also increase as the wall spacing decreases. This is due to the walls blocking the diffusion of vorticity away from the sphere as it accelerates leading to higher shear stresses. <p>In an unbounded fluid, the falling sphere will drag fluid along with it, and further from the sphere, fluid will move upward to compensate. It was found that there is a critical wall spacing that will completely prevent this recirculation in the gap between the sphere and the wall. In the 80%wt glycerol case, this critical wall spacing is between h/d = 1.2 and 1.5, and in the 100%wt glycerol case the critical wall spacing is between h/d = 1.5 and 6.0.

This thesis describes an investigation of the velocity field in a fluid around a solid sphere undergoing transient motion parallel to, and midway between, two plane walls. Particle Image Velocimetry (PIV) was used to measure the velocity at many discrete locations in a plane that was perpendicular to the walls and included the centre of the sphere. The transient motion was achieved by releasing the sphere from rest and allowing it to accelerate to terminal velocity. <p>To avoid complex wake structures, the terminal Reynolds number was kept below 200. Using solutions of glycerol and water, two different fluids were tested. The first fluid was 100%wt glycerol, giving a terminal Reynolds number of 0.6 which represents creeping flow. The second solution was 80%wt glycerol yielding a terminal Reynolds number of 72. For each of these fluids, three wall spacings were examined giving wall spacing to sphere diameter ratios of h/d = 1.2, 1.5 and 6.0. Velocity field measurements were obtained at five locations along the transient in each case. Using Y to denote the distance the sphere has fallen from rest, velocity fields were obtained at Y/d = 0.105, 0.262, 0.524, 1.05, and 3.15. <p>It was observed that the proximity of the walls tends to retard the motion of the sphere. A simple empirical correlation was fit to the observed sphere velocities in each case. A wall correction factor was used on the quasi-steady drag term in order to make the predicted unbounded terminal velocity match the observed terminal velocity when the walls had an effect. While it has been previously established that the velocity of a sphere is retarded by the proximity of walls, the current research examined the link between the motion of the sphere and the dynamics of the fluid that surrounds it. By examining the velocity profile between the surface of the sphere at the equator and the wall, it was noticed that the shear stresses acting on the sphere increase throughout the transient, and also increase as the wall spacing decreases. This is due to the walls blocking the diffusion of vorticity away from the sphere as it accelerates leading to higher shear stresses. <p>In an unbounded fluid, the falling sphere will drag fluid along with it, and further from the sphere, fluid will move upward to compensate. It was found that there is a critical wall spacing that will completely prevent this recirculation in the gap between the sphere and the wall. In the 80%wt glycerol case, this critical wall spacing is between h/d = 1.2 and 1.5, and in the 100%wt glycerol case the critical wall spacing is between h/d = 1.5 and 6.0.

Numerical simulations have been done with the CHEMKINsoftware to study different aspects of wall effects in thecombustion of lean, laminar and premixed flames in anaxisymmetric boundary-layer flow. The importance of the chemical wall effects compared to thethermal wall effects caused by the development of the thermaland velocity boundary layer has been investigated in thereaction zone by using different wall boundary conditions, walltemperatures and fuel/air ratios. Surface mechanisms include acatalytic surface (Platinum), a surface that promotesrecombination of active intermediates and a completely inertwall with no species and reactions as the simplest possibleboundary condition. When hydrogen is the model fuel, the analysis of the resultsshow that for atmospheric pressure and a wall temperature of600 K, the surface chemistry gives significant wall effects atthe richer combustion case (f=0.5), while the thermal andvelocity boundary layer gives rather small effects. For theleaner combustion case (f=0.1) the thermal and velocityboundary layer gives more significant wall effects, whilesurface chemistry gives less significant wall effects comparedto the other case. For methane as model fuel, the thermal and velocity boundarylayer gives significant wall effects at the lower walltemperature (600 K), while surface chemistry gives rather smalleffects. The wall can then be modelled as chemically inert forthe lean mixtures used (f=0.2 and 0.4). For the higher walltemperature (1200 K) the surface chemistry gives significantwall effects. For both model fuels, the catalytic wall unexpectedlyretards homogeneous combustion of the fuel more than the wallthat acts like a sink for active intermediates. This is due toproduct inhibition by catalytic combustion. For hydrogen thisoccurs at atmospheric pressure, but for methane only at thehigher wall temperature (1200 K) and the higher pressure (10atm). As expected, the overall wall effects (i.e. a lowerconversion) were more pronounced for the leaner fuel-air ratiosand at the lower wall temperatures. To estimate a possible discrepancy in flame position as aresult of neglecting the axial diffusion in the boundary layerassumption, calculations have been performed with PREMIX, alsoa part of the CHEMKIN software. With PREMIX, where axialdiffusion is considered, steady, laminar, one-dimensionalpremixed flames can be modelled. Results obtained with the sameinitial conditions as in the boundary layer calculations showthat for the richer mixtures at atmospheric pressure the axialdiffusion generally has a strong impact on the flame position,but in the other cases the axial diffusion may beneglected. Keywords:wall effects, laminar premixed flames,platinum surfaces, boundary layer flow / QC 20100504

Increased knowledge into the physics and chemistrycontrolling emissions from flame-surface interactions shouldhelp in the design of combustion engines featuring improvedfuel economy and reduced emissions. The overall aim of this work has been to obtain afundamental understanding of wall-related, premixed combustionusing numerical modeling with detailed chemical kinetics. Thiswork has utilized CHEMKIN®, one of the leading softwarepackages for modeling combustion kinetics. The simple fuels hydrogen and methane as well as the morecomplex fuels propane and gasified biomass have been used inthe model. The main emphasis has been on lean combustion, andthe principal flow field studied is a laminar boundary layerflow in two-dimensional channels. The assumption has been madethat the wall effects may at least in principle be the same forlaminar and turbulent flames. Different flame geometries have been investigated, includingfor example autoignition flames (Papers I and II) and premixedflame fronts propagating toward a wall (Papers III and IV).Analysis of the results has shown that the wall effects arisingdue to the surface chemistry are strongly affected by changesin flame geometry. When a wall material promoting catalyticcombustion (Pt) is used, the homogeneous reactions in theboundary layer are inhibited (Papers I, II and IV). This isexplained by a process whereby water produced by catalyticcombustion increases the rate of the third-body recombinationreaction: H+O2+M ⇔ HO2+M. In addition, the water produced at higherpressures increases the rate of the 2CH3(+M) ⇔ C2H6(+M) reaction, giving rise to increased unburnedhydrocarbon emissions (Paper IV). The thermal coupling between the flame and the wall (theheat transfer and development of the boundary layers) issignificant in lean combustion. This leads to a sloweroxidation rate of the fuel than of the intermediatehydrocarbons (Paper III). Finally in Paper V, a well-known problem in the combustionof gasified biomass has been addressed, being the formation offuel-NOx due to the presence of NH3 in the biogas. A hybridcatalytic gas-turbine combustor has been designed, which cansignificantly reduce fuel-NOx formation. Keywords:wall effects, premixed flames, flamequenching, numerical modeling, CHEMKIN, boundarylayerapproximation, gasified biomass, fuel-NOx, hybrid catalytic combustor. / QC 20100504

Ce mémoire présente des travaux de thèse consacrés à la caractérisation et la modélisation des hétérogénéités spatio-temporelles dans les écoulements granulaires cisaillés entre deux parois rigides. De nombreuses simulations ont permis de révéler le rôle crucial des dimensions de l’écoulement et l’influence des interactions des grains avec les parois (avec leur rugosité) sur le comportement global. Pour des systèmes allant jusqu'à une épaisseur de cent diamètres, des profils de vitesse non homogènes ont été mis en évidence, alors que la contrainte cisaillante est constante dans le volume, mettant en défaut le modèle viscoplastique au sein de l’écoulement. Pour réconcilier ces deux observations, nous avons enrichi le modèle viscoplastique en reliant la viscosité à une variable interne qui porte la perturbation due à la présence des parois. Cette nouvelle formulation de la viscosité permet de rétablir la validité d'une loi de comportement locale prenant en compte simultanément l’épaisseur de l’écoulement, la rugosité des parois et le nombre inertiel.Cette dépendance de la viscosité à une variable interne liée à la connectivité des grains ou à leur agitation à compacité fixée, suggère que, d’une manière générale,les écoulements granulaires doivent être décrits en termes d’au moins trois paramètres en fonction du nombre inertiel : le coefficient de frottement, la compacité et la connectivité. / This PhD work is devoted to the description and modeling of spatiotemporal inhomogeneities in granular flows sheared between two rigid walls. Our extensive simulations reveal the crucial role played by flow dimensions and the interactions of the grains with the walls and their roughness. For granular systems with increasingly larger thickness, non uniform strain profiles are evidenced while the shear stress remains uniform. This observation contradicts the common viscoelastic approach based on inertial number in the bulk of the flow. In order to reconcile these observations, we propose a viscoplastic model by a introducing an internal variable carrying the wall-induced perturbations of the flow. This re-formulation of granular viscosity reaffirms the local rheology by accounting for flow thickness, wall routines and inertialeffects. The well-defined dependence of the viscosity on an internal variable pertaining to grain connectivity or kinematic randomness at constant packing fraction, suggests that granular flows should be described by at least three parameters as a function of the inertial number:friction coefficient, packing fraction and connectivity.

The provision of clean drinking water typically involves treatment processes to remove contaminants. The conventional process involves coagulation with hydrolysing metal salts, typically of aluminium (‘alum’) or trivalent iron (‘ferric’). Along with the product water this also produces a waste by-product, or sludge. The fact of increasing sludge production — due to higher levels of treatment and greater volume of water supply — conflicts with modern demands for environmental best practice, leading to higher financial costs. A further issue is the significant quantity of water that is held up in the sludge, and wasted. / One means of dealing with these problems is to dewater the sludge further. This reduces the volume of waste to be disposed of. The consistency is also improved (e.g. for the purpose of landfilling). And a significant amount of water can be recovered. The efficiency, and efficacy, of this process depends on the dewaterability of the sludge.In fact, good dewaterability is vital to the operation of conventional drinking water treatment plants (WTP’s). The usual process of separating the particulates, formed from a blend of contaminants and coagulated precipitate, relies on ‘clarification’ and ‘thickening’, which are essentially settling operations of solid–liquid separation.WTP operators — and researchers — do attempt to measure sludge dewaterability, but usually rely on empirical characterisation techniques that do not tell the full story and can even mislead. Understanding of the physical and chemical nature of the sludge is also surprisingly rudimentary, considering the long history of these processes. / The present work begins by reviewing the current state of knowledge on raw water and sludge composition, with special focus on solid aluminium and iron phases and on fractal aggregate structure. Next the theory of dewatering is examined, with the adopted phenomenological theory contrasted with empirical techniques and other theories.The foundation for subsequent analyses is laid by experimental work which establishes the solid phase density of WTP sludges. Additionally, alum sludges are found to contain pseudoböhmite, while 2-line ferrihydrite and goethite are identified in ferric sludges. / A key hypothesis is that dewaterability is partly determined by the treatment conditions. To investigate this, numerous WTP sludges were studied that had been generated under diverse conditions: some plant samples were obtained, and the remainder were generated in the laboratory (results were consistent). Dewaterability was characterised for each sludge in concentration ranges relevant to settling, centrifugation and filtration using models developed by LANDMAN and WHITE inter alia; it is expressed in terms of both equilibrium and kinetic parameters, py(φ) and R(φ) respectively.This work confirmed that dewaterability is significantly influenced by treatment conditions.The strongest correlations were observed when varying coagulation pH and coagulant dose. At high doses precipitated coagulant controls the sludge behaviour, and dewaterability is poor. Dewaterability deteriorates as pH is increased for high-dose alum sludges; other sludges are less sensitive to pH. These findings can be linked to the faster coagulation dynamics prevailing at high coagulant and alkali dose.Alum and ferric sludges in general had comparable dewaterabilities, and the characteristics of a magnesium sludge were similar too.Small effects on dewaterability were observed in response to variations in raw water organic content and shearing. Polymer flocculation and conditioning appeared mainly to affect dewaterability at low sludge concentrations. Ageing did not produce clear changes in dewaterability.Dense, compact particles are known to dewater better than ‘fluffy’ aggregates or flocs usually encountered in drinking water treatment. This explains the superior dewaterability of a sludge containing powdered activated carbon (PAC). Even greater improvements were observed following a cycle of sludge freezing and thawing for a wide range of WTP sludges. / Further aspects considered in the present work include deviations from simplifying assumptions that are usually made. Specifically: investigation of long-time dewatering behaviour, wall effects, non-isotropic stresses, and reversibility of dewatering (or ‘elasticity’).Several other results and conclusions, of both theoretical and experimental nature, are presented on topics of subsidiary or peripheral interest that are nonetheless important for establishing a reliable basis for research in this area. / This work has proposed links between industrial drinking water coagulation conditions, sludge dewaterability from settling to filtration, and the microstructure of the aggregates making up that sludge. This information can be used when considering the operation or design of a WTP in order to optimise sludge dewaterability, within the constraints of producing drinking water of acceptable quality.