Swallowing accelerometry may provide a portable and cost-effective bedside alternative to currently available instrumentation. In this study, dual-axis accelerometry signals were collected simultaneous to videofluoroscopic records from 29 pediatric participants (age 6.8 $\pm$ 4.8 years; 20 males) previously diagnosed with neurogenic dysphagia. Videofluoroscopic records were reviewed by a clinical expert to extract swallow timings and ratings. The dual-axis accelerometry signals corresponding to each identified swallow were pre-processed, segmented and trimmed prior to feature extraction from time, frequency, time-frequency and information theoretic domains. Feature space dimensionality was reduced via principal components. Using 8-fold cross-validation, 16-18 dimensions and a support vector machine classifier with an RBF kernel, an adjusted accuracy of 89.6\% $\pm$ 0.9 was achieved for the discrimination between swallows with and without airway entry. Our results suggest that dual-axis accelerometry has merit in the non-invasive detection of unsafe swallows in children and deserves further consideration as a pediatric medical device.

Despite the inbuilt advantages offered by 5-axis machining, the manufacturing industry has not widely adopted this technology due to the high cost of machines and insufficient support from CAD/CAM systems. Companies are used to 3-axis machining and the operators are in many cases not yet ready for 5-axis machining in terms of training and programming. An effective solution for this 5 axis problem is a graduated migration through the use of 3+2-axis machining. The objective of this research is to develop and implement a machining technique that uses the simplicity of 3-axis tool positioning and the flexibility of 5-axis tool orientation, to machine complex surfaces. This technique, 3+2-axis machining, divides a surface into patches and then machines each patch using a fixed tool orientation. The tool orientation and section boundaries are determined to minimize the overall machining time. For each section the tool orientation is different but remains constant while machining this section. The number of patches selected for machining has a direct impact on the machining time. If the number of patches is small, the shape of the tool may vary greatly from that of the surface, which can result in smaller side-step distances. In contrast, a large number of patches leads to a better match between the tool and the workpiece, but it also leads to many re-orientations of the part as the tool moves between patches. Also, if the number of patches is large, the size of the patches will be reduced which will result in shorter tool passes that limit the tools ability to achieve the commanded feed rate. The optimum number of patches is a compromise between increasing the side step associated with large patches and the increase in time due to re-orientation of part and tool movement between patches. To find the optimal partition, a series of simulation tests are conducted to find the partition that would lead to the smallest machining time. This work presents the application of well known methods from Pattern Recognition and newly developed methods by the current author that were adapted for surface machining and boundary identification. This work also presents the methodology required to generate tool paths for 3+2-axis machining, which includes an explanation of the procedures required to determine an appropriate tool orientation, feed direction, tool path trajectory and tool parameters for patch-by-patch machining. These parameters are determined independently for each patch and aim at reducing the time required to machine a surface while maintaining the surface specifications. This work presents the surface partitioning scheme and the method of selecting optimum number of partitions along with actual machining experiments. Machining tests on four different surfaces were conducted to demonstrate the efficiency of the proposed technique. The results show that 3+2-axis machine reduced machining times over 3-axis ball nose machining and 5-axis machining using the “Sturz” method. Also, since the tool axis remains fixed during cutting, the tool offers constant feed rates and a better surface finish compared to simultaneous 5-axis.

The project contains a force analysis of the vertical axis wind turbine Lucia's supporting arms and a measuring device to experimentally measure the forces is made. The forces between the supporting arms and the tower are calculated theoretically and then simulated by a computere. A measuring devise is then designed to measure the forces experimentally. The forces acting on the attachment between the supporting arms and the tower is primarily the centripetal force, gravitational force and the aerodynamic forces on the rotor wings. The maximum forces were theoretically calculated and is 13.38 kN along the x-axis, -0.25 kN along the y-axis and then 0.5 kN along the z-axis. The axis are acording to a rotational reference system where the x-axis runs along the supporting arm and the y-axis runs along the axis of rotation. The maximum torque that occurs is 0.53 kNm along the y-axis and 1.29 kNm along the z-axis. The size of the forces have been confirmed with a deviation of up to 1.8 % in the simulation using SolidWorks 2010. For the experimental measurements a measuring device has been developed which consists of S-load cells with wave indicator and transmitter, an attachment for the measuring equipment and distanceplates to stabilize the rotor. S-load cells, wave indicator and transmitter were ordered and drawings for the attachment of the measuring equipment and spacer plates was done. The eigenfrequencies and the stress have been investigated for the parts. The eigenfrequencies for the wind turbine was estimated to decline up to 13 % when the measuring device was mounted and the lowest Factor of Safety was 1.67. Before the attachment of the measuring device and the spacer plates can be ordered the attachment of the supporting arms, how the loadcells should be attached to the device and the safety margins need to be examined.

Despite the inbuilt advantages offered by 5-axis machining, the manufacturing industry has not widely adopted this technology due to the high cost of machines and insufficient support from CAD/CAM systems. Companies are used to 3-axis machining and the operators are in many cases not yet ready for 5-axis machining in terms of training and programming. An effective solution for this 5 axis problem is a graduated migration through the use of 3+2-axis machining. The objective of this research is to develop and implement a machining technique that uses the simplicity of 3-axis tool positioning and the flexibility of 5-axis tool orientation, to machine complex surfaces. This technique, 3+2-axis machining, divides a surface into patches and then machines each patch using a fixed tool orientation. The tool orientation and section boundaries are determined to minimize the overall machining time. For each section the tool orientation is different but remains constant while machining this section. The number of patches selected for machining has a direct impact on the machining time. If the number of patches is small, the shape of the tool may vary greatly from that of the surface, which can result in smaller side-step distances. In contrast, a large number of patches leads to a better match between the tool and the workpiece, but it also leads to many re-orientations of the part as the tool moves between patches. Also, if the number of patches is large, the size of the patches will be reduced which will result in shorter tool passes that limit the tools ability to achieve the commanded feed rate. The optimum number of patches is a compromise between increasing the side step associated with large patches and the increase in time due to re-orientation of part and tool movement between patches. To find the optimal partition, a series of simulation tests are conducted to find the partition that would lead to the smallest machining time. This work presents the application of well known methods from Pattern Recognition and newly developed methods by the current author that were adapted for surface machining and boundary identification. This work also presents the methodology required to generate tool paths for 3+2-axis machining, which includes an explanation of the procedures required to determine an appropriate tool orientation, feed direction, tool path trajectory and tool parameters for patch-by-patch machining. These parameters are determined independently for each patch and aim at reducing the time required to machine a surface while maintaining the surface specifications. This work presents the surface partitioning scheme and the method of selecting optimum number of partitions along with actual machining experiments. Machining tests on four different surfaces were conducted to demonstrate the efficiency of the proposed technique. The results show that 3+2-axis machine reduced machining times over 3-axis ball nose machining and 5-axis machining using the “Sturz” method. Also, since the tool axis remains fixed during cutting, the tool offers constant feed rates and a better surface finish compared to simultaneous 5-axis.

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In motion planning, high clearance paths are favorable due to their increased visibility and reduction of collision risk such as the safety of problems involving: human- robot cooperation. One popular approach to solving motion planning problems is the Probabilistic Roadman Method (PRM), which generates a graph of the free space of an environment referred to as a roadmap. In this work we describe a new approach to making high clearance paths when using PRM The medial axis is useful for this since it represents the set of points with maximal clearance and is well defined in higher dimensions. However it can only be computed exactly in workspace. Our goal is to generate roadmaps with paths following the medial axis of an environment without explicitly computing the medial axis. One of the major steps of PRM is local planning: the planning of motion between two nearby nodes PRMs have been used to build roadmaps that have nodes on the medial axis but so far there has been no local planner method proposed for connecting these nodes on the medial axis. These types of high clearance motions are desirable and needed in many robotics applications. This work proposes Medial Axis Local Planner (MALP), a local planner which attempts to connect medial axis configurations via the medial axis. The recursive method takes a simple path between two medial axis configurations and attempts to deform the path to fit the medial axis. This deformation creates paths with high clearance and visibility properties. We have implemented this local planner and have tested it in 2D and 3D rigid body and 8D and 16D fixed base articulated linkage environments. We compare MALP with a straight-line local planner (SL), a typical local planer used in motion planning that interpolated along a line in the planning space. Our results indicate that MALP generated higher clearance paths than SL local planning. As a result, MALP found more connections and generated fewer connected components as compared to connecting the same nodes using SL connections. Using MALP connects noes on the medial axis, increasing the overall clearance of the roadmap generated.

No description available.

Impellers are important components in the field of precision machine, energy technology, and aerospace industries. Due to their complex geometries and a higher degree of interference, multi-axis machines are requested to product impellers with desired accuracy. The object of this thesis is to improve the five-axis machining efficiency and accuracy. The involved techniques include: the construction of equal depth and equal width tool paths in rough machining, the methods for interference check and avoidance, error evaluation and control of chordal deviation and scallop height, as well as three and five dimension NURBS (Non-uniform Rational B-splines) tool paths generation by a least squares method.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Cadmium (Cd) is a nonessential metal present in sublethal concentrations within the aquatic environment. Cd is an endocrine disruptor and high concentrations of this metal suppress stressor-induced cortisol production in fish. However, few studies have examined the effect of Cd at concentrations that are environmentally relevant on the functioning of the hypothalamus-pituitary-interrenal (HPI) axis. The HPI axis activity is essential in the stressor-induced cortisol production, a highly conserved adaptive response to stress in vertebrates. Elevation of plasma glucose in response to a rise in plasma cortisol is mediated through steroid activation of glucocorticoid receptors (GRs), but the mechanism of action of Cd in disrupting target tissue cortisol action is not known in fish. The overall objective of this thesis was to examine the impact of sublethal and environmentally relevant levels of Cd on the stress response and target tissue metabolic capacities, and to investigate the mechanisms of action of this metal in disrupting cortisol production and target tissue cortisol action in rainbow trout (Oncorhynchus mykiss). The impact of subchronic exposure to environmentally relevant levels of Cd on metabolic capacity and stress performance was identified through a 28 day (d) in vivo exposure of juvenile rainbow trout to either of two Cd concentrations (0.75 µg/L or 2.0 µg/L). During the exposure period, juvenile rainbow trout accumulated Cd within the liver, kidney and gills, but were able to adapt to exposure concentrations as no changes were observed in plasma cortisol, glucose and lactate levels. However, changes in abundance of mRNAs encoding proteins involved in corticosteroidogenesis, including melanocortin 2 receptor (MC2R), steroidogenic acute regulatory protein (StAR) and P450 side chain cleavage enzyme (P450scc), and liver GR protein expression suggesting endocrine disruption over the 28 d period. Also, target tissue metabolic capacities, including lower liver glycogen content and changes in intermediary metabolic enzyme activities in the liver and gill, were compromised by the 28 d exposure to Cd. The response to a secondary handling stressor at either 7 or 28 d exposure was attenuated suggesting that subchronic exposure to low levels of Cd disrupts the highly conserved adaptive stress response in rainbow trout. Upon further investigation using in vitro head kidney slices exposed to 0, 10, 100 or 1000 nM of Cd and stimulated with adrenocorticotropic hormone (ACTH), a similar inhibition of cortisol production was observed, as demonstrated in vivo, suggesting that Cd disrupts interrenal corticosteroidogenesis in fish. The impact of Cd on ACTH-stimulated cortisol production involved the suppression in the abundances of MC2R, StAR and P450scc transcripts. This response was also mimicked when head kidney slices from 7 d Cd exposed fish were incubated ex vivo with ACTH confirming that interrenal tissue is a key target for endocrine disruption by Cd. In both the in vitro and ex vivo incubations of head kidney slices 8-Bromo-cAMP (a cAMP analog) completely abolished the Cd-mediated cortisol inhibition demonstrating for the first time that Cd disruption of corticosteroidogenesis is occurring upstream of cAMP production. Further investigation of Cd-mediated impact on MC2R showed alterations in MC2R mRNA transcripts during in vivo exposure after 7 days and an attenuation of MC2R mRNA levels after Cd-exposed fish were subjected to a handling stressor. Disruptions in the mRNA abundance of MC2R was associated with disruptions of melanocortin receptor accessory protein 1 (MRAP1), but not MRAP2; a phenomenon that was also observed in ex vivo head kidney slices. Cell transfection studies confirmed that rainbow trout MC2R/MRAP1 receptor complex displayed decreased activity in the presence of Cd. Taken together these results suggest that Cd directly targets the MC2R/MRAP1 complex to inhibit ACTH-stimulated cortisol production in juvenile rainbow trout. In addition to Cd inhibiting interrenal steroidogenesis, the results also suggest that Cd may impact the negative feedback regulation of cortisol through the suppression of brain mineralocorticoid receptor (MR), but this requires further investigation. At the target tissue level, Cd by itself did not significantly affect liver metabolism, but inhibited the cortisol-induced glucose production in liver slices. This involved suppression of GR protein expression along with the suppression of GR-responsive genes, including phosphoenolpyruvate carboxykinase (PEPCK) and suppressor of cytokines signaling 1 (SOCS1) and changes in enzyme activities, including hexokinase, glucokinase, pyruvate kinase and PEPCK, pointing to a disruption in liver GR signaling by Cd. Altogether, Cd exposure disrupts the organismal stress responses in juvenile rainbow trout. Furthermore, Cd impairs the ability of juvenile rainbow trout to respond to a secondary stressor, which is a vital adaptive process that is fundamental to successful stress performance. Most importantly, these studies highlight for the first time that disruption of the HPI axis to attenuate cortisol production occurs at the level of the MC2R/MRAP1 complex, suggesting that the mechanism of action for attenuation of cortisol occurs at the level of MC2R activation. Also, GR signaling is a key target for Cd and may be a mechanism leading to altered metabolic capacities in stressed fish from Cd-contaminated sites. Overall environmentally relevant levels of Cd disrupt cortisol production and target tissue action of this steroid in rainbow trout.