Regularized Stokeslets Lines Suitable for Slender Bodies in Viscous Flow

Slender-body approximations have been successfully used to explain many phenomena in low-Reynolds number fluid mechanics. These approximations typically use a line of singularity solutions to represent flow. These singularities can be difficult to implement numerically because they diverge at their origin. Hence, people have regularized these singularities to overcome this issue. This regularization blurs the force over a small blob and thereby removing divergent behaviour. However, it is unclear how best to regularize the singularities to minimize errors. In this paper, we investigate if a line of regularized Stokeslets can describe the flow around a slender body. This is achieved by comparing the asymptotic behaviour of the flow from the line of regularized Stokeslets with the results from slender-body theory. We find that the flow far from the body can be captured if the regularization parameter is proportional to the radius of the slender body. This is consistent with what is assumed in numerical simulations and provides a choice for the proportionality constant. However, more stringent requirements must be placed on the regularization blob to capture the near field flow outside a slender body. This inability to replicate the local behaviour indicates that many regularizations cannot satisfy the no-slip boundary conditions on the body’s surface to leading order, with one of the most commonly used blobs showing an angular dependency of velocity along any cross section. This problem can be overcome with compactly supported blobs, and we construct one such example blob, which can be effectively used to simulate the flow around a slender body.

Rapid GAIT adoption for snake-like locomotion (RGASL)

Snake-like robots are low centre of gravity because they are limbless, they also have slender bodies composed of multiple actuating segments. Because of these features, snake robots are widely considered to be most adaptable among all land-based mobile robots. The multi-segmented body that provides their defining characteristic, adaptivity, also brings about the quandary of controlling many actuating segments simultaneously to create directd locomotion. Various methods for snake robot locomotion have been proposed for relatively smooth and flat surfaces. Currently there is no snake robot designed or locomotion method capable of resolving the directed mobility problem in situations where the snake robot is stuck at an impasse, or when it encounters disjointed terrains. There is no method to rapidly create new locomotion that addresses the problem or extensive time delay. This thesis makes the contribution of a modular snake robot called Striker and an elegant solution to create new snake-like robot locomotion on-the-fly, called the Explicit Gait Training (EGT) method. The EGT method allows trainer(s) to rapidly train new kinds of locomotion to address any situation at hand using their knowledge, experiences or even trial and error. The third contribution is the Standard Mobility for Snake Robots (SMMSR) is proposed as a standard platform to evaluate the evvectiveness of snake robot locomotion.

Rapid GAIT adoption for snake-like locomotion (RGASL)

Snake-like robots are low centre of gravity because they are limbless, they also have slender bodies composed of multiple actuating segments. Because of these features, snake robots are widely considered to be most adaptable among all land-based mobile robots. The multi-segmented body that provides their defining characteristic, adaptivity, also brings about the quandary of controlling many actuating segments simultaneously to create directd locomotion. Various methods for snake robot locomotion have been proposed for relatively smooth and flat surfaces. Currently there is no snake robot designed or locomotion method capable of resolving the directed mobility problem in situations where the snake robot is stuck at an impasse, or when it encounters disjointed terrains. There is no method to rapidly create new locomotion that addresses the problem or extensive time delay. This thesis makes the contribution of a modular snake robot called Striker and an elegant solution to create new snake-like robot locomotion on-the-fly, called the Explicit Gait Training (EGT) method. The EGT method allows trainer(s) to rapidly train new kinds of locomotion to address any situation at hand using their knowledge, experiences or even trial and error. The third contribution is the Standard Mobility for Snake Robots (SMMSR) is proposed as a standard platform to evaluate the evvectiveness of snake robot locomotion.

You've Got to Be Real: Authenticity, Performativity and Micro-Celebrity in South Africa

For many young black South African women, the competitive arena of social media offers access to significant social and cultural capital, which can be invaluable in the unequal context in which they live. In order to succeed in this high stakes environment young women carefully construct the identities and idealised selves that they present on platforms like Instagram. They display a lifestyle of glamorous consumption, showcasing exclusive brands and fashionable items and modifying and modelling themselves to fit a beauty ideal that emphasises youth, light skin, slender bodies and straight hair. As well as these physical features, young women on Instagram are also hyper-aware of the need to appear “authentic”: to have their online lives and selves appear natural, easy and free of artifice in order to further enhance their status as role models to other women. This article draws from in-depth interviews with 10 black South African “micro-celebrities.” It reveals the central role of authenticity in these young women's online performances of self, and considers the contradictory impulses that require them to both “feel” and “appear” real. Within the framework of existing hegemonic structures, these women appear to be exercising their freedom as neoliberal citizens within a post-feminist setting. Despite the promises of freedom, however, this article reveals the way in which their performances of selfhood are powerfully constrained by normative ideas about aspiration and success.