Thesis (MTech (Sports Science Radiology))--Cape Peninsula University of Technology, 2006 / The knee is one ofthe most complicated joints in the body. The deep infrapatellar bursa being only a small water-pocket and forming a small part of the knee. The deep infrapatellar bursa can get inflamed and cause great discomfort, especially to professional sportsmen and -women. If such a inflammation is present, a common treament option are to inject a cortisone solution into the bursa for quick relieve and healing. This study was performed to investigate the specific ultrasound features of a normal deep infrapatellar bursa. Thus enableing more specific and accurate diagnosis of deep infrapatellar bursitis or not, which in turn leads to quicker recovery ofthe patients. A total of280 males and females from various population groups were recruited for the study. Subjects were categorized into different subgroups depending on their gender, ethnicity, competitiveness in sport, sport type practised and previous knee problems. These subgroups enabled a more individual specific DIB measurement. A high frequency ultrasound examination ofboth knees ofall recruits were performed. The deep infrapatellar bursa was located by slightly flexing the knee and applying not to much pressure with the probe whilst scanning. Three measurements, antero-posterio (AP), cranio-caudal (CC) and width measurements, were recorded ofeach individuals left and right deep infrapatellar bursa (DIB). The results ofthe DIB measurements were compared to results from a ultrasound study perfonned in Gennany and a favourable comparison could be made. MRI studies of the DIB performed in Turkey and Switzerland differed greatly from those of this study and Germany. This study could serve as a valuable source ofreference to sonographer, radiologist and orthopaedic surgeons when investigating the deep infrapatellar bursa. A statistical significant difference was shown for males having a larger DIB than female, for competitive sports people having a larger Dill than non-competitive sports people and also inactive people; and rugby players (as a sport type) have larger DIBs than cricketers, runners, soccer players and cyclists. Another surprising factor was the amazing ultrasound detection rate of the deep infrapatellar bursa, which allows for future easy and confident assessing of the DIB by ultrasound.

Thesis (MTech (Radiography))--Cape Peninsula University of Technology, 2006. / The knee is one of the most complicated joints in the body. The deep infrapatellar bursa being only a small water-pocket and forming a small part of the knee. The deep infrapatellar bursa can get inflamed and cause great discomfort, especially to professional sportsmen and -women. If such a inflammation is present, a common treament option are to inject a cortisone solution into the bursa for quick relieve and healing. This study was performed to investigate the specific ultrasound features of a normal deep infrapatellar bursa. Thus enableing more specific and accurate diagnosis of deep infrapatellar bursitis or not, which in turn leads to quicker recovery of the patients.

Os modelos existentes de propagação de ondas de ultra-som em meios líquidos e sólidos consideram a geração e recepção das ondas produzidas por transdutores simulados segundo o modelo do pistão plano ou com excitações cuja amplitude varia radialmente no pistão. Esses modelos são simplificados e não explicam completamente o comportamento real de transdutores de ultra-som interagindo com líquidos e sólidos. As verificações experimentais de propagação da onda de ultra-som em meios líquidos mostram que a onda de borda é diferente da onda plana. Observa-se também a existência de outras ondas não previstas nos modelos anteriores. Essas ondas são conhecidas como ondas head. A utilização do método dos elementos finitos (MEF) para a modelagem de propagação de ondas de ultra-som, incluindo o transdutor piezelétrico, permite a obtenção de resultados realísticos, conseguindo assim descrever com maior precisão o comportamento do transdutor e das ondas de ultra-som se propagando em diferentes meios e interagindo com defeitos que se comportam como refletores. Apesar disso, os resultados desses modelos dependem das características precisas dos materiais que compõem o transdutor. O transdutor de ultra-som é composto por uma cerâmica piezelétrica, por camadas de casamento e de retaguarda que geralmente são compósitos de epóxi com alumina e epóxi com tungstênio respectivamente, e pelo encapsulamento. Neste trabalho é analisada a resposta transiente de um transdutor circular de 2 MHz, com diâmetro de 12,7 mm, banda larga. O modelo do transdutor foi implementado com o método de elementos finitos. A análise transiente pelo MEF é implementada com o software ANSYS. Na primeira parte do trabalho o transdutor é analisado no modo de transmissão em água. Os resultados do modelo com MEF foram comparados com os resultados do modelo do pistão plano e com verificações experimentais obtidas em tanque de imersão com um hidrofone tipo agulha. Na segunda parte é realizada a análise do transdutor operando em modo pulso-eco radiando em peças de teste com e sem defeito, utilizando acoplamento direto e acoplamento por buffer de água. Os resultados do MEF apresentam boa concordância com os resultados obtidos experimentalmente. / Simple models for ultrasonic wave propagation in liquid and solid media consider the wave generation and reception by transducers that behave as plane pistons. These models are simplified and they do not explain completely the behavior of an ultrasonic transducer when interacting with other media. Experimental verifications of ultrasonic wave propagation in liquid show that the pressure amplitude of the edge wave is different from the plane wave. Also it is observed the existence of other types of waves not foreseen in these previous models. These waves are known as head waves. More realistic models for ultrasonic wave propagation are obtained using the finite element method (FEM). These models include the piezoelectric transducer, thus, describing with higher precision the behavior of the transducer and the ultrasonic waves propagating in different mediums and interacting with defects. The precision of the models depends on the accurate determination of the mechanical and electrical properties of the involved materials. The ultrasonic transducer is composed by a piezoelectric ceramic, a matching layer and a backing layer that are generally made by epoxy/alumina and epoxy/tungsten composites respectively. In this work it is analyzed the transient response of a circular transducer of 12.7 mm diameter and 2 MHz center frequency. The transducer model was implemented with the finite element method. The FEM transient analysis was executed in the ANSYS software. In the first part of the work the transducer is analyzed in transmission mode in water and the MEF results are compared with the plane piston model and with experimental verifications using a hydrophone. In the second part it is carried at the transducer analysis operating in pulse-echo mode radiating into test pieces with and without defects, using direct and water buffer coupling. The MEF results show good agreement with the results obtained experimentally in the laboratory.

M.Tech. / To determine whether a combination of real-time B-Mode ultrasound, Doppler Color flow and Power Doppler flow mapping would be reliable in differentiating benign from malignant breast nodules in an attempt to avoid unnecessary biopsies, where after ultrasound guidelines would be formulated. A quantitative cross-sectional comparative descriptive design in a study population which consisted of 62 women over the age of 35 years who came to Klerksdorp Radiology services for mammography. Both breast ultrasound imaging and mammography was used as a routine procedure as part of the workup for the classification of breast nodules, before histologic specimens were obtained. All nodules were classified according to the ultrasonographic BI-RADS lexicon and compared with the pathologic results. Of the 63 patients, 63 breast nodules were detected and confirmed by biopsy. Thirty seven (59%) nodules were found to be malignant and 26 (41%) were benign according to biopsy results. Mammography had 87% sensitivity and ultrasound 60% sensitivity in detecting malignancy. It is recommended that B-mode, Color Doppler flow and Power Doppler flow mapping be used in combination with mammography for screening as a gold standard.

No description available.

ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / This paper describes a short distance telemetry network which measures and relays time, space, and position information among a group of ground vehicles. The goal is to allow a lead vehicle to be under human control, or perhaps controlled using advanced autonomous path planning and navigation tools. The telemetry network will then allow a series of inexpensive, unmanned vehicles to follow the lead vehicle at a safe distance. Ultrasonic and infrared signals will be relayed between the vehicles, to allow the following vehicles to locate their position, and track the lead vehicle.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / Medicine / Master / Doctor of Medicine

Micro-assembly is of crucial importance in industry nowadays. Nevertheless, currently applied processes require improvements. Indeed, when dealing with the assembly of submillimetric components, usually neglected surface forces disturb the manipulation task. They are responsible for the component sticking to the gripper, because of downscaling laws. A promising strategy to tackle adhesion consists in working without contact. The present dissertation is focused on contactless handling with acoustic levitation. The advantages of contactless handling, the physical principles suitable for levitation and their applications are detailed. The opportunity for new handling strategies are shown. Acoustic levitation appears as the most fitted principle for micro-assembly. The elements to model acoustic forces are analysed and performances of existing modellings are assessed. A general numerical model of acoustic forces is implemented and theoretically validated with literature benchmarks. A fully automated modular levitator prototype is designed and used to experimentally validate the implemented numerical model. Specific instrumentations and protocols are developed for the acoustic force measurements. The numerical model is finally applied to the real levitator. Modelling results are used to support experimental observations: the optimisation of the levitator resonance, the influence of the reflector shape, the dynamical study of the component oscillations, the stability with lateral centring forces and rotation torques, the component insertion and extraction from the levitator, the effect of pressure harmonics on the acoustic forces, and the manipulation of non spherical components. Acoustic forces are experimentally measured and a very good agreement with the modellings is obtained. Consequently, the implemented simulation tool can successfully be applied to a complex manipulation task with a component of any shape in a real levitator.