A crucial parameter in the production of mechanical pulp through refining is energy consumption. Although low consistency (LC) refining has been shown to be more energy efficient than conventional high consistency refining, the degradation of mechanical properties of the end-product paper due to fiber cutting has limited the widespread adoption of LC refining. In conventional control strategies, the onset of fiber cutting is determined by post-refining measurement of pulp properties which does not enable rapid in-process adjustment of refiner operation in response to the onset of fiber cutting. In this dissertation, we exploit a piezoelectric force sensor to detect the onset of fiber cutting in real time. Detection of the onset of fiber cutting is potentially beneficial in low consistency refining as part of a control system to reduce fiber cutting and increase energy efficiency. The sensor has a probe which replaces a short length of a refiner bar, enabling measurement of normal and shear forces applied to pulp fibers by the refiner bars. The custom-designed sensors are installed in an AIKAWA pilot-scale 16-in. single-disc refiner at the Pulp and Paper Centre at the University of British Columbia. Trials were run using different pulp furnishes and refiner plate patterns at differing rotational speeds and a wide range of plate gaps. Pulp samples were collected at regular intervals and the pulp and paper properties were measured. We observe distinct transitions in the parameters that characterize the distributions of peak normal and shear forces which consistently correspond to the onset of fiber cutting. In addition, the analysis of the power spectrum of the sensor data shows that the magnitude of the dominant frequency can be used as an indicator of fiber cutting. The power of the time domain signal of the normal force is shown to be the most reliable and consistent indication of the onset of fiber cutting. This parameter consistently identifies the onset of fiber cutting, as determined by fiber length data, for all tested pulp furnishes and plate patterns. In addition, we investigate the effect of pulp furnish and plate pattern on bar forces in LC refining. For tested pulp furnishes and at all plate gaps, the plate with higher bar edge length (which has smaller bar width and groove width) results in lower mean peak normal and shear forces but higher mean coefficient of friction. Moreover, at the onset of fiber cutting, the mean peak normal force of softwood pulp is higher than that for hardwood pulp. Our results also show that the mean coefficient of friction at the onset of fiber cutting is a function of plate gap, pulp furnish, and plate pattern. / Graduate / 2019-01-09

This is a `sandwich thesis' comprising three distinct research streams I have pursued during the course of my master's degree. The first two streams have concluded, each resulting in a manuscript that is presented as a separate chapter of this thesis. The third research stream is ongoing, but preliminary results are presented in another chapter of this thesis. The first research stream presented in this thesis concerns the development of a technique to produce droplets with diameters as small as 5 microns with an extremely narrow size distribution in comparison to other methods. Other advantages of this technique, known as he snap-offf method, include its simplicity and ease of tuning droplet size. The results of this research are presented in chapter 3 in the form of a manuscript that is currently in press. The second research stream of this thesis explores the physics that drive droplet snap-off. A model was developed to predict the size of droplets, dependent on fluid properties, system geometry, and fluid flow rate. Experiments examined each of these parameters in turn, providing a cohesive understanding of the mechanism behind droplet snap-off. Multiple unanticipated predictions of the model were also verified experimentally. This research is presented in chapter 4 as a manuscript that will be submitted shortly. The final research stream of this thesis investigates forces in emulsions as they relate to a transition from glassy to crystalline dynamics. Specifically, 2D aggregates of droplets were compressed with micropipettes, providing both imaging of cluster evolution, as well as the force applied during compression. This research stream has demonstrated qualitative differences between droplet clusters that differ in composition so as to behave like crystals, glasses, or intermediate states. More quantitative analysis is required before this research stream is ready to be published. Preliminary results are presented in chapter 5. / Thesis / Master of Science (MSc)

The objective of this research was to investigate the affects of various generator plate size, D/d ratio, stroke frequency and slurry concentration, for a plate type vortex ring mixer, on the drag force and power consumption. In this case CaCO3 aqueous slurry was used for the investigation. The generator plate was driven using an AC induction motor with gear type speed reducer which was controlled using a frequency inverter and a mechanism for converting rotational into translational motion. This drive system resulted in sinusoidal motion of the generator plate. The applied force, the displacement of the generator plate and the input power were measured using measurement cell developed for this purpose. The viscosity was also measured. The data were analyzed, organized and presented using appropriate graphs. The force measurement data showed that drag force was mainly affected by the size of generator plate and its oscillating frequency. Larger generator plates had greater drag force acting on them and, therefore, required more power for running. Oscillating frequency had similar effect on drag force and power consumption. However, tested CaCO3 slurry concentrations showed to have no significant affect on these two parameters. Drag force results obtained during this study are considered to be reasonably representative, while power consumption data, although representative for this system, will probably be different for different drive systems employed. / Thesis / Master of Engineering (ME)

Existing thrust measurement systems (TMSs) at NASA Stennis Space Center use strain gauges and flux plates to measure forces produced by a test article. Alignment and calibration can take two weeks or more every time a piece of hardware or test article is changed. Cross axis loading is also problematic because it is impossible to perfectly align the flex plates and strain gauges in the thrust direction. In response to these problems, a magnetically levitated thrust measurement system has been proposed and a 300lb capacity demonstrator has been designed and built. In this design, the magnetic bearings work concurrently as support bearings and force measurement devices. The demonstrator consists of a floating frame that is completely levitated within a fixed frame by four support bearings carrying loads in the x- and y-direction and seven thrust bearings carrying loads in the z- or thrust direction. Joe Imlach of Imlach Consulting Engineering designed the demonstrator and magnetic bearing components, while Virginia Tech's role has been the application of the multipoint calibration technique including code development, the implementation of a 128-channel data acquisition system, and the overall test verification of the TMS demonstrator.A turnbuckle assembly and magnetostrictive actuator are used in series with a conventional load cell for static and dynamic testing, respectively. Both current based and flux based force equations were used to measure the reaction forces at the bearings. The static results using the current based equations including the current based fringing equations resulted in accuracies of 93% of full load, while the static results using the flux based equations including the flux based fringing equations resulted in accuracies of 99.5% of full load. These accuracies can be compared to accuracies of 83-90% seen in previous work using magnetic bearings to measure forces by monitoring currents and to accuracies of about 99% in previous work using magnetic bearings to measure forces by monitoring fluxes. All of the improved accuracies were made possible through the implementation of a calibration technique known as the multipoint method and the implementation of a gap dependent fringing correction factor developed by Joe Imlach. The demonstrator was not outfitted with accelerometers so the inertia of the floating frame could not be accounted for, limiting the scope of dynamic testing. However, the tests confirmed the ability of the demonstrator to measure dynamic loads in general. / Master of Science

A l’échelle du micromètre, les forces de surface appliquées à l’objet deviennentprépondérantes par rapport aux forces volumiques. Dans le but de s’affranchirdu phénomène d’adhésion causé par ces effets d’échelle, la microrobotique sanscontact apparaît comme une voie prometteuse. Nos travaux sont à la jonctionentre la microrobotique et la chimie des surfaces. L’objectif de cette thèse est deproposer une méthode de micromanipulation innovante exploitant la chimie dessurfaces afin de contrôler les forces électrostatiques. Nous exploitons les chargesélectriques créées par les fonctions chimiques dépendantes du pH lorsqu’elles sontplacées en milieu liquide. La modélisation des interactions entre une surface et unmicro-objet fonctionnalisés repose sur l’exploitation du phénomène de la doublecouche électrique. Deux principes de fonctionnalisation de surface ont été utilisés;les monocouches auto-assemblées (APTES) qui sont facilement mises en oeuvreet les films de polymères (polyaniline, polypyrrole) par voie électrochimique quipermettent d’obtenir des dépôts localisés. Les résultats obtenus mettent en évidencel’intérêt de l’exploitation des forces électrostatiques d’origine chimique pour desapplications de micromanipulation. / On the micrometer scale, surface forces applied to the object are significant comparedto volume forces. In order to overcome the adhesion phenomenon caused by thesescale effects, contactless microrobotics appears promising. Our work is mergingwith microrobotics and chemistry of surfaces. The objective of this thesis is topropose a method of micromanipulation based on innovative surface chemistry tocontrol electrostatic forces. The principle is based on the electric charges generatedby pH dependent chemical functions when placed in liquid medium. Modeling ofthe interaction between a surface and a micro- functionalized object is based onthe exploitation of the phenomenon of the electrical double layer. Two surfacefunctionalization principles were used, (i) self-assembled monolayers (APTES),and (ii) electrodeposition of polymer films (polyaniline , polypyrrole) that enablelocalized deposits. The results highlight the interest of using electrostatic chemicalforces for micromanipulation applications.

This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.

This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.

This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.

During the undertaken research and development, two major systems were designed. These were; a prototype force sensor, and a movement measurement system. Both the developed systems were designed for the intended field of insect research, but were developed using very different underlying principles. The force measurement system uses the piezo-electric effect induced in piezo-electric bimorph elements to produce a measure of force exerted on the sensor. The movement measurement system on the other hand uses computer vision (CV) techniques to find and track the three dimensional (3D) position of markers on the insect, and thereby record the pose of the insect. To further increase the usefulness of the two measurement systems, a prototype graphical user interface (GUI) was produced to encapsulate the functionality of the systems and provide an end user with a more complete and functional research tool. The GUI allows a user to easily define the parameters required for the CV operations and presents the results of these operations to the user in an easily understood visual format. The GUI is also intended to display force measurements in a graphical means to make them easily interpreted. The GUI has been named Weta Evaluation Tracking and Analysis (WETA). Testing on the developed prototype force sensor shows that the piezo-electric bimorph elements provide an adequate measure of force exerted on them, when the voltage signal produced by an element is integrated. Furthermore, the testing showed that the developed force sensor layout produces an adequate measure of forces in the two horizontal linear degrees of freedom (DOF), but the prototype did not produce a good measure of forces in the vertical linear DOF. Development and testing of the movement measurement system showed that stereo vision techniques have the ability to produce accurate measurements of 3D position using two cameras. Although, when testing these techniques with one of the cameras replaced by a mirror, the system produced less than satisfactory results. Further testing on the feature detection and tracking portions of the movement system showed that even though these systems were implemented in a relatively simple way, they were still adequate in their associated operations. However, it was found that with some simple changes in colour spaces used during feature detection, the performance of the feature detection system in varying illumination was greatly improved. The tracking system on the other hand, operated adequately using just its associated basic principles. During the development of both prototype measurement systems, a number of conclusions were formulated that indicated areas of future development. These areas include; advanced force sensor configurations, force sensor miniaturisation, design of a force plate, improvement of feature detection and tracking, and refining of the stereo vision equipment.

This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.