During routine measurements of body composition using a 153Gd based dual photon densitometer, it was observed that negative values were being obtained for the body fat fraction in some adults, in children and in small animals. In these three groups, there appears to be a body size dependent error whereby the measured fat fraction becomes increasingly negative as subject size becomes smaller. The fat fraction is derived from relating the measured mass attenuation coefficient of soft tissue to an internal calibration based on the use of water and lard as substitutes for muscle and fat. To investigate whether this procedure for instrument calibration is the cause of the fat fraction errors, soft tissue phantoms which contained known amounts of fat, water and protein were prepared. Over the range of fat fractions used, accurate results were obtained. By using prepared soft tissue and water phantoms it was established that the measured fat fraction incorrectly became progressively smaller as object thickness decreased and incorrectly increased with object thickness. However, accurate measurements were obtained if the equivalent tissue thickness is greater than 9 em and less tnan 16 em of water. Equally reproducible measurements are obtained at all thicknesses investigated. When dual photon measurements of body composition in 13 adolescent females were compared with measurements obtained from skinfold thicknesses or bioimpedance, there was good agreement between techniques but dual photon results demonstrated a broader range of variation with body size. Comparisons between dual photon absorptiometry derived body composition measurements of 52 male athletes with results obtained from under water weighing allowed for derivation of a simple correction factor for the accuracy errors due to body size. / Thesis / Master of Science (MSc)

This is a ‘sandwich thesis’ consisting of a publication that I contributed to during my M.Sc. work. The thesis begins with an introduction section in Chapter 1 that discusses the relevant physical concepts to the work performed in the publication. These topics include, polymers in section 1.1, fluid dynamics in section 1.2, and capillary effects in section 1.3. Chapter 2 contains an experimental technique section that maps out the experiments performed in the manuscript. The manuscript, Chapter 3, details the capillary driven levelling of thin polymer step that is supported by an immiscible polymer film and the dissipation of the capillary energy of the system. We find that the dissipation mechanism depends strongly on the viscosity ratio between the top and the bottom films. We developed a model of the energy dissipation that agrees well with the experimental results. / Thesis / Master of Science (MSc)

When a droplet is placed on a soft material, surface tension forces from the droplet are able to deform the substrate. This thesis explores the effect of substrate stiffness on energy dissipation as a droplet is slid along a soft material. We find behaviour is characterised by two regimes separated by the lengthscale of the deformation in the substrate. For films approximately the lengthscale of the deformation, dissipation increases with thickness. As the thickness becomes much larger than the size of deformation, there is a plateau in dissipation. This result agrees with the model we use to understand energy dissipation in these systems. / Thesis / Master of Science (MSc)

Rehabilitation interventions for motor practice are necessary for patients with impaired hand function to regain strength and range of motion. Clinical rehabilitative therapies are found to be costly and insufficient in terms of frequency due to their limited accessibility. Recently, advancements in robotic devices have improved accessibility and have been useful in facilitating repetitive tasks. This work presents a magnetically-controlled soft robotic glove with a quick and tunable stiffening mechanism that is also safe for the patients and conveniently portable. The magnetic control is achieved by employing a unique array of EPMs within a medium of MRF-immersed fibers. This array of EPMs enables customized rehabilitation depending on the patient’s pathology. The glove is designed to have a discontinuous structure that mimics the anatomy of the fingers, which comprises joints and linkages. The glove is tested for flexion, extension, abduction, and pinch grip exercises, and the impact of the stiffness change provided by the glove is validated through an EMG sensor. This design offers a portable, safe, easy-to-control, and customizable wearable rehabilitative technology for patients with hand impairment. / 2026-05-23T00:00:00Z

abstract: This work presents the integration of user intent detection and control in the development of the fluid-driven, wearable, and continuum, Soft Poly-Limb (SPL). The SPL utilizes the numerous traits of soft robotics to enable a novel approach to provide safe and compliant mobile manipulation assistance to healthy and impaired users. This wearable system equips the user with an additional limb made of soft materials that can be controlled to produce complex three-dimensional motion in space, like its biological counterparts with hydrostatic muscles. Similar to the elephant trunk, the SPL is able to manipulate objects using various end effectors, such as suction adhesion or a soft grasper, and can also wrap its entire length around objects for manipulation. User control of the limb is demonstrated using multiple user intent detection modalities. Further, the performance of the SPL studied by testing its capability to interact safely and closely around a user through a spatial mobility test. Finally, the limb’s ability to assist the user is explored through multitasking scenarios and pick and place tests with varying mounting locations of the arm around the user’s body. The results of these assessments demonstrate the SPL’s ability to safely interact with the user while exhibiting promising performance in assisting the user with a wide variety of tasks, in both work and general living scenarios. / Dissertation/Thesis / Masters Thesis Biomedical Engineering 2018

In comparison to the flow in a rigid channel, there is a multi-fold reduction in the transition Reynolds number for the flow in a micro channel when one of the walls is made sufficiently soft, due to a dynamical instability induced by the fluid-wall coupling. The flow after transition is characterized using Particle Image Velocimetry (PIV) in the x − y plane where x is the stream-wise direction and y is the cross-stream co-ordinate along the small dimension of the channel of height 0.2 − 0.3mm. For the two different soft walls of shear modulus 18 kPa and 2.19 kPaused here, the transition Reynolds number is about 250 and 330 respectively. The deformation of the microchannel due to the applied pressure gradient is measured in the experiments, and is used to predict the laminar mean velocity profiles for comparison with the experimental results. The mean velocity profiles in the microchannel are in quantitative agreement with those predicted for the laminar flow before transition, but are flatter near the centerline and have higher gradients at the wall after transition. The flow after transition is characterized by a mean velocity profile that is flatter at the center and steeper at the walls in comparison to that for a laminar flow. The root mean square of the stream-wise fluctuating velocity shows the characteristic sharp increase from the wall and a maximum close to the wall, as observed in turbulent flows in rigid-walled channels. However, the profile is asymmetric with a significantly higher maximum close to the soft wall in comparison to that close to the hard wall, and the Reynolds stress is found to be non-zero at the soft wall, indicating that there is a stress exerted by fluid velocity fluctuations on the wall. The turbulent energy production profile has a maximum at the soft wall, in contrast to the flow at a rigid surface where the turbulent energy production is zero at the wall (due to the zero Reynolds stress). The maximum of the root mean square of the velocity fluctuations and the Reynolds stress (divided by the fluid density) in the soft-walled microchannel for Reynolds numbers in the range 250-400, when scaled by suitable powers of the maximum velocity, are comparable to those in a rigid channel at Reynolds numbers in the range 5000-20000. The near-wall velocity profile shows no evidence of a viscous sub-layer for (yv∗/ν) as low as 2, but there is a logarithmic layer for (yv∗/ν) up to about 30, where the von Karman constants are very deferent from those for a rigid-walled channel. Here, v∗ is the friction velocity, ν is the kinematic viscosity and y is the distance from the soft surface. . The surface of the soft wall in contact with the fluid is marked with dye spots to monitor the deformation and motion along the fluid-wall interface. The measured displacement of the surface in the stream-wise direction, which is of the order of 5 − 12µm, is consistent with that calculated on the basis of linear elasticity. Low-frequency oscillations in the displacement of the surface are observed after transition in both the stream-wise and span-wise directions, indicating that the turbulent velocity fluctuations are dynamically coupled to motion in the solid. Modification of soft-wall turbulence in a micro channel due to the addition of small amounts of polymer The modification of soft-wall turbulence in a microchannel due to the addition of small amounts of polymer is experimentally studied using Particle Image Velocimetry (PIV) to measure the mean and the fluctuating velocities. The micro channels are of rectangular cross-section with height about 160 µm, width about 1.5 mm and length about 3 cm, with three walls made of hard Poly-dimethylsiloxane (PDMS) gel, and one wall made of soft PDMS gel with an elasticity modulus of about 18 kPa. A dynamical instabilty of the laminar flow due to the fluid-wall coupling, and a transition to turbulence, is observed at a Reynolds number of about 290 for the flow of pure water in the soft-walled microchannel (Verma and Kumaran, J. Fluid Mech., 727, 407-455, 2013). Solutions of polyacrylamide of molecular weight 5 × 106 and mass fraction up to 50 ppm, and of molecular weight 4 × 104 and mass fraction up to 1500 ppm, are used in the experiments. In all cases, the solutions are in the dilute limit be-low the critical concentration where the interactions between polymer molecules become important. The modification of the fluid viscosity due to addition of polymer molecules is small; the viscosity of the solutions with the highest polymer concentration exceed those for pure water by about 10% for the polymer with molecular weight 5 × 106, and by about 5% for the polymer with molecular weight 4 × 104. Two distinct types of flow modifications below and above a threshold mass fraction for the polymer, cTHRESHOLD , which is about 1 ppm for the polyacrylamide with molecular weight 5 × 106, and about 500 ppm for the polyacrylamide with molecular weight 4 × 104. As the polymer mass fraction increases up to the threshold value, there is no change in the transition Reynolds number, but there is significant turbulence attenuation the root mean square velocities in the stream wise and cross-stream directions decrease by a factor of 2, and the Reynolds stress decreases by a factor of 4 in comparison to that for pure water. When the polymer concentration increases beyond the threshold value, there is a decrease in the decrease in the transition Reynolds number by nearly one order of magnitude, and a further decrease in the intensity of the turbulent fluctuations. The lowest transition Reynolds number of about 35 for the solution of polyacrylamide with molecular weight 5 × 106 and mass fraction 50 ppm. For the polymer solutions with the highest concentrations, the fluctuating velocities in the stream wise and cross-stream direction are lower by a factor of 5, and the Reynolds stress is lower by a factor of 10, in comparison to pure water. Despite the significant turbulence attenuation, a sharp increase in the intensity of the fluctuating velocities is evident at transition for all polymer concentrations. Transitions to deferent kinds of turbulence in a channel with soft walls The flow in a rectangular channel with walls made of soft polyacrylamide gel is studied to examine the effect of soft walls on transition and turbulence. The width of the channel is much larger than the height, so that the flow can be considered approximately two-dimensional, the wall thickness is much larger than the channel height (smallest dimension), the bottom wall is fixed to a substrate and the top wall is unrestrained. The fluid velocity is measured using Particle Image Velocimetry, while the wall motion is studied by embedding beads in the soft wall, and measuring the time-variation of the displacement both parallel and perpendicular to the surface. As the Reynolds number increases, two different flow regimes are observed in sequence. The first is the ‘soft-wall turbulence’ resulting from a dynamical instability of the base flow due to the fluid-wall coupling. The flow in this case exhibits many of the features of the turbulent flow in a rigid channel, including the departure of the velocity profile from the parabolic profile, and the near-wall maxima in the stream-wise root mean square fluctuating velocity. However, there are also significant differences. The turbulence intensities, when scaled by suitable powers of the mean velocity, are much larger than those after the hard-wall laminar-turbulent transition at a Reynolds number of about 1000. The Reynolds stress profiles do not decrease to zero at the walls, indicating that the wall motion plays a role in the generation of turbulent fluctuations. There is no evidence of a viscous sub-layer close to the wall to within the experimental resolution. The mean velocity profile does satisfy a logarithmic law close to the surface within a region between 2-30 wall units from the surface, but the von Karman constants are very different from those for the hard-wall turbulence. The wall displacement measurements indicate that there is no observable motion perpendicular to the surface, but displacement fluctuations parallel to the surface are observed after transition, coinciding with the onset of velocity fluctuations in the fluid. The fluid velocity fluctuations are symmetric about the center line of the channel, and they show relatively little downstream variation after a flow development length of about 5 cm. As the Reynolds number is further increased, there is a second ‘wall flutter’ transition, which involves visible downstream traveling waves in the top (unrestrained) wall alone. Wall displacement fluctuations of low frequency (less than about 500 rad/s) are observed both parallel and perpendicular to the wall. The mean velocity profiles and turbulence intensities are asymmetric, with much larger turbulence intensities near the top wall. There is no evident logarithmic profile close to either the top or bottom wall. Fluctuations are initiated at the entrance of the test section, and the fluctuation intensities decrease with downstream distance, the fluctuation intensities first rapidly increase and then decrease as the Reynolds number is increased. For a channel with relatively small height (0.6 mm), the transition Reynolds number for the soft-wall instability is lower the hard-wall transition Reynolds number of about 1000, and the laminar flow becomes unstable to the soft-wall instability leading to soft-wall turbulence and then to wall flutter as the Reynolds number is increased. For a channel with relatively large height (1.8 mm), the transition Reynolds number for the soft-wall instability is higher than 1000, the flow first undergoes the hard-wall laminar-turbulent transition at a Reynolds number of about 1000, the turbulent flow undergoes the soft-wall transition leading to soft-wall turbulence, and then to wall flutter.

Cette thèse se situe dans le domaine de la programmation par contraintes (CP). Plus précisément, nous nous intéressons au problème de satisfaction de contraintes pondérées (WCSP), qui est un problème d'optimisation pour lequel plusieurs formes de cohérences locales souples telles que, par exemple, la cohérence d’arc existentielle directionnelle (EDAC*) et la cohérence d’arc virtuelle (VAC) ont été proposées durant ces dernières années. Dans ce cadre, nous adoptons une perspective différente en revisitant la propriété bien connue de la substituabilité. Tout d’abord, nous précisons les relations existant entre la substituabilité de voisinage souple (SNS) et une propriété appelée pcost qui est basée sur le concept de surcoût de valeurs (par le biais de l'utilisation de paires de surcoût). Nous montrons que sous certaines hypothèses, pcost est équivalent à SNS, mais que dans le cas général, elle est plus faible que SNS prouvée être coNP-difficile. Ensuite, nous montrons que SNS conserve la propriété VAC, mais pas la propriété EDAC. Enfin, nous introduisons un algorithme optimisé et nous montrons sur diverses séries d’instances WCSP l’intérêt pratique du maintien de pcost avec AC*, FDAC* ou EDAC*, au cours de la recherche. Nous introduisons un algorithme optimisé et nous étudions la relation existante entre SNS et les différentes cohérences. Nous présentons aussi un nouveau type de propriétés pour les WCSPs. Il s'agit de la cohérence de tuples (TC) dont l'établissement sur un WCN est effectué grâce à une nouvelle opération appelée TupleProject. Nous proposons également une version optimale de cette propriété, OTC, qui peut être perçue comme une généralisation de OSAC (Optimal Soft Arc Consistency). Enfin, nous étendons la notion de substituabilité souple aux tuples. / This thesis is in the field of constraint programming (CP). More precisely, we focus on the weighted constraint satisfaction problem (WCSP), which is an optimization problem for which many forms of soft local (arc) consistencies have been proposed such as, for example, existential directional arc consistency (EDAC) and virtual arc consistency (VAC) in recent years. In this context, we adopt a different perspective by revisiting the well-known property of (soft) substitutability. First, we provide a clear picture of the relationships existing between soft neighborhood substitutability (SNS) and a tractable property called $pcost$ which allows us to compare the cost of two values (through the use of so-called cost pairs). We prove that under certain assumptions, $pcost$ is equivalent to SNS but weaker than SNS in the general case since we show that SNS is coNP-hard. We also show that SNS preserves the property VAC but not the property EDAC. Finally, we introduce an optimized algorithm and we show on various series of WCSP instances, the practical interest of maintaining $pcost$ together with AC*, FDAC* or EDAC*, during search. We also present a new type of properties for WCSPs called tuples consistency (TC). Enforcing TC is done through a new operation called TupleProject. Moreover, we propose an optimal version of this property, OTC, which can be seen as a generalization of OSAC (Optimal Soft Arc Consistency). Finally, we extend soft substitutability concept to tuples.

This paper deals with a novel active bending soft body that employs metamaterials and combines soft behavior, integrated actuation, low complexity and a high density of producible forces and moments. The presented concept consists of a tube-like structure with tailored, unconventional material properties which enable the generation of a bending deformation and/or moment when circumferential stress and/or strain is induced. Circumferential actuation can be generated by a difference in pressure between the internal and external surface of the tube or, alternatively, by distributed expansion actuators that act radially or tangentially (e.g. shape memory wires). In addition to an analytical model, this paper also presents a design procedure and deals with the implementation of the proposed concept in a functional prototype and its experimental characterization.

Indiana University-Purdue University Indianapolis (IUPUI) / SASTMTM is a myofascial technique used to mobilize soft tissue and aid in the elongation of soft tissue and create physiological change. The purpose of the study was to determine the acute effects of Sound Assisted Soft Tissue Mobilization (SASTMTM) on lower extremity hamstring strength (isokinetic & isometric) and flexibility. Thirty division III male athletes with limited ROM of ≤ 90o of knee extension with 90o of hip flexion while lying supine consented to volunteer. Each subject was treated and measured through a double-blinded experimental design where the subjects and tester were unaware of the real treatment being administered and measured. The research consisted of 4 visits (familiarization/baseline, and 3 data collection session). Testing sessions were conducted a week after the baseline session, followed by two sessions, 2 days and a week after the 1st session. Three different modalities (SASTMTM, Therapeutic Ultrasound and “The Stick”) were performed on a treatment leg, and the opposite leg served as a control. Data collection consisted of a warm-up on a cycle ergometer followed by one randomly chosen modality on the treatment leg. Data collection was conducted using a Cybex 300-isokinetic device and a digital goniometer. Isokinetic strength testing was performed at 60, 180 and 240o/s. Isometric testing was collected at 45o of knee flexion. Repeated two-way ANOVA’s (3-Treatment x 3-Time) were used for statistical analyses to determine the effects of interventions and the time on strength and flexibility. The statistical analyses resulted in no significant results (p≤.05) for acute effects for either strength or flexibility with respect to time, treatment or treatment and time interactions.

When our society is undergoing a shift from a product driven to a service driven economy, this affects the competences that is needed in the work with IT. Research regarding soft skills and evaluation of IT-project success have been conducted throughout the years. There is, however a gap in knowledge around which these soft skills are and how they bring value to different stakeholders in the IT-industry. This research paper therefore aims to fill this gap and answer the questions: What is soft skills? and What are the possibilities and challenges associated with soft skills? To answer these questions data is collected through literature and interviews with people within the IT-field. The research paper focuses on an IT-consultancy and the majority of the interviews are therefore conducted with people within this consultancy. To make a broader understanding on the subject two additional interviews are conducted with representatives from two other IT-organisations. The results from the data collection show that soft skills include: analytical skills, empathic skills, leadership skills, social skills and problem solving skills. The results also show that soft skills lead to better use of systems for customers, more business opportunities for the IT- consultancies and the provider. It also becomes apparent that soft skills come with different types of challenges. These are issues such as how to argue the importance of soft skills for customers, as well as how to value the performed labour carried out by a consultant in possession of soft competence. Our conclusion shows that soft skills are needed in IT- projects and that the competence must get more space both in the literature and within the industry. To solve the issues, communication is concluded to be the key. This study contributes with a framework for how value is contributed to all the included parties in an IT-project.