A feature-based approach to the Computer-Aided Design of sculptured products

Computer-Aided Design systems offer considerable potential for improving design process efficiency. To reduce the 'ease of use' barrier hindering full realisation of this potential amongst general mechanical engineering industries, many commercial systems are adopting a Feature-Based Design (FBD) metaphor. Typically the user is allowed to define and manipulate the design model using interface elements that introduce and control parametric geometry clusters, with engineering meaning, representing specific product features (such as threaded holes, slots, pockets and bosses). Sculptured products, such as golf club heads, shoe lasts, crockery and sanitary ware, are poorly supported by current FBD systems and previous research, because their complex shapes cannot be accurately defined using the geometrically primitive feature sets implemented. Where sculptured surface regions are allowed for, the system interface, data model and functionality are little different from that already provided in many commercial surface modelling systems, and so offer very little improvement in ease of use, quality or efficiency. This thesis presents research to propose and develop an FBD methodology and system suitable for sculptured products. [Continues.

DETERMINING SUBJECT-SPECIFIC PARAMETERS FOR A COMPUTER SIMULATION MODEL OF A ONE-HANDED TENNIS BACKHAND

A subject-specific computer simulation model of a one-handed tennis backhand was developed to investigate the mechanisms that may cause injury to the elbow. Subject-specific parameters for the ball, racket and human were determined. Firing tennis balls from a pneumatic air cannon onto a force plate enabled parameters to be determined for a spring-damper model of a tennis ball. Data from further ball cannon tests allowed the spring constants for the stringbed and the coefficient of friction between the ball and stringbed to be optimised using a computer simulation model. The fundamental modal frequencies of the racket frame were obtained by Doppler laser vibrometry and its inertia parameters were determined from the results of oscillation and balance tests. An elite tennis player performed isovelocity tests at the wrist, elbow and shoulder to establish torque / angle / angular velocity relationships. Inertia parameters of the human segments were calculated from ninety-five anthropometric measurements using a geometric model

Experiences of delayed maturation in female vocational ballet students: An interpretative phenomenological analysis

Introduction: There is a well-established bias toward late maturing females in the context of ballet, with up to 70% of professionals delayed in maturation. The timing of maturation has implications for physical and psychological outcomes which are likely to be amplified in dance. The aim of this research was to explore the role of maturity timing in adolescent dance students' experiences of vocational ballet training. Methods: Semi-structured interviews were carried out with 28 adolescent female dancers of differing maturity timing across three vocational ballet schools in the UK. Interpretative phenomenological analysis was employed in the analysis of data. This study comprises findings from the nine late maturing dancers within the sample. Results: Late maturing dancers perceived a number of aesthetic and functional advantages. The aesthetic advantages noted by the dancers are congruent with the well-established bias toward a later maturing physique for ballet; being ‘small’ and not having ‘bits’ is advantageous for these dancers in terms of maintaining a more pre-pubescent look and thereby conforming more easily to the expectations of the ballet world. However, dancers in this study perceived some significant drawbacks. Despite aesthetic advantages, later maturing dancers were disadvantaged by the current training system which sees them undertaking the most crucial training period during their most rapid period of growth. Conclusions: Greater consideration of maturation is needed within training systems and further research is warranted to understand these experiences in more depth and their implications for the physical and psychological wellbeing of young people in dance.</p

Hyponatremia and Congestive Heart Failure: A Marker of Increased Mortality and a Target for Therapy

Heart failure is one of the most common chronic medical conditions in the developed world. It is characterized by neurohormonal activation of multiple systems that can lead to clinical deterioration and significant morbidity and mortality. In this regard, hyponatremia is due to inappropriate and continued vasopressin activity despite hypoosmolality and volume overload. Hyponatremia is also due to diuretic use in an attempt to manage volume overload. When hyponatremia occurs, it is a marker of heart failure severity and identifies patients with increased mortality. The recent introduction of specific vasopressin-receptor antagonists offers a targeted pharmacological approach to these pathophysiological derangements. Thus far, clinical trials with vasopressin-receptor antagonists have demonstrated an increase in free-water excretion, improvement in serum sodium, modest improvements in dyspnea but no improvement in mortality. Continued clinical trials with these agents are needed to determine their specific role in the treatment of both chronic and decompensated heart failure

Software Engineering meets Problem-based Learning

A problem-driven approach for teaching software engineering to undergraduate students is entering its third year at the Department of Computer Science at NUI, Maynooth

The evaluation of new multi-material human soft tissue simulants for sports impact surrogates

Previous sports impact reconstructions have highlighted the inadequacies in current measures to evaluate the effectiveness of personal protective equipment (PPE) and emphasised the need for improved impact surrogates that provide a more biofidelic representation of human impact response. The skin, muscle and subcutaneous adipose tissues were considered to constitute the structures primarily governing the mechanical behaviour of the human body segment. A preceding study by Payne et al. (in press) investigated the formulation and characterisation of muscle tissue simulants. The present study investigates the development of bespoke blends of additive cure polydimethysiloxane (PDMS) silicones to represent both skin and adipose tissues using the same processes previously reported. These simulants were characterised mechanically through a range of strain rates and a range of hyperelastic and viscoelastic constitutive models were evaluated to describe their behaviour. To explore the worth of the silicone simulants, finite element (FE) models were developed using anthropometric parameters representative of the human thigh segment, derived from the Visible Human Project. The multi-material silicone construction was validated experimentally and compared with both organic tissue data from literature and commonly used single material simulants: Dow Corning Silastic 3480 series silicones and ballistics gelatin when subject to a representative sports specific knee impact. Superior biofidelic performance is reported for the PDMS silicone formulations and surrogate predictions

Show Me the Money: Economic Evaluations of Opioid Use Disorder Interventions

This brief summarizes a new systematic review of economic evaluations of treatments for substance use disorders. The review reveals strong evidence that methadone maintenance therapy is an economically advantageous form of treatment; the economic evidence for buprenorphine and naltrexone treatments is more limited

Design of human surrogates for the study of biomechanical injury: a review

Human surrogates are representations of living human structures employed to replicate “real-life” injurious scenarios in artificial environments. They are used primarily to evaluate personal protective equipment (PPE) or integrated safety systems (e.g., seat belts) in a wide range of industry sectors (e.g., automotive, military, security service, and sports equipment). Surrogates are commonly considered in five major categories relative to their form and functionality: human volunteers, postmortem human surrogates, animal surrogates, anthropomorphic test devices, and computational models. Each surrogate has its relative merits. Surrogates have been extensively employed in scenarios concerning “life-threatening” impacts (e.g., penetrating bullets or automotive accidents). However, more frequently occurring nonlethal injuries (e.g., fractures, tears, lacerations, contusions) often result in full or partial debilitation in contexts where optimal human performance is crucial (e.g., military, sports). Detailed study of these injuries requires human surrogates with superior biofidelity to those currently available if PPE designs are to improve. The opportunities afforded by new technologies, materials, instrumentation, and processing capabilities should be exploited to develop a new generation of more sophisticated human surrogates. This paper presents a review of the current state of the art in human surrogate construction, highlighting weaknesses and opportunities, to promote research into improved surrogates for PPE development

The role of the racket in high-speed tennis serves

The high-speed first serve has become an increasingly dominant factor in tennis, raising concerns over the influence modern racket technology has on the game. One concern is that rackets are now too powerful and so overemphasise a player’s ability to produce fast serves. This may help explain the ‘penalty shootout’ scenario, where match result id dictated by the relative speed and consistency of the players’ first serves. There is some concern that on the faster surfaces, maximum service speeds have reached, or are approaching, the service returnee’s reaction threshold, making it virtually impossible for players to return the ball. To shed light on the issue the factors relating to ‘racket power’, the amount a racket magnifies a player’s innate ability to impart linear velocity to a tennis ball, need to be considered. Various studies have been performed that shed some light on the subject. This paper presents an overview of the published literature related to ‘racket power’ in the game of tennis, a review of previous research on specific and sometimes controversial issues. Areas meriting further investigation are identified to encourage future research into racket power