No description available.

Thesis (MEducation)--University of South Australia, 2003.

Angle section members, used in open engineering structures, have been known to experience large amplitude oscillations when exposed to normal atmospheric winds, and in a few instances failure has been reported. The bluff geometry together with low natural frequency makes these members susceptible to aeroelastic vibrations of a vortex resonant or galloping nature. The thesis aims at studying the nature of the aerodynamic forces and the resulting instabilities for the safe design of the structures. It presents information on the aerodynamics and dynamics of the angle section during stationary, plunging, torsional and combined plunging-torsional conditions. From the measurements on stationary angle models, it is possible to predict the critical vortex resonant wind speeds for various angles of attack. The large variations of the unsteady aerodynamic coefficients indicate the dependence of the resonant instability on model orientation. Incorporating the stationary aerodynamic loadings, the quasi-steady analysis is able to predict the galloping instability and resulting amplitude and buildup time response. The absence of torsional galloping during the experiment is substantiated by the theory which shows the instability to occur only at high wind speeds or for systems with very low damping. The dynamical study demonstrates that structural angle sections are susceptible in general, to combined plunging and torsional vibrations. The nature of the instability depends on such system parameters as damping, natural frequency, angle of attack, section size, etc. However, due to the existence of two distinct families of virtual hinge points, it is possible to represent the motion as predominantly plunging or torsion. Furthermore, the frequency of the coupled motion as well as the type and range of the instability are found to be similar to those in the single degree of freedom. This makes it possible to obtain pertinent information by studying, both experimentally and theoretically, the plunging and torsional degrees of freedom, separately. During plunging resonance, the angle section experiences a vortex capture phenomenon where the shedding frequency is controlled by the cylinder motion over a finite wind speed range. On the other hand, the torsional vibration shows a vortex control condition over a large velocity range where the vortex shedding governs the frequency of oscillation and follows the stationary model Strouhal curve. Compared to the stationary and torsional results, the fluctuating pressures on the angle surface during plunging resonance are substantially larger in magnitude with less amplitude modulation and phase variation. Consequently, the unsteady aerodynamic coefficients increase with this instability. During resonance in either degree of freedom, the vortex velocity and longitudinal spacing remain essentially unaltered, however, the wake width experiences substantial increase with plunging motion. It appears that the torsional resonance has virtually no effect on the vortex shedding or wake characteristics. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

No description available.

Every (convex) star polygon with n vertices can be associated with a permutation on {1,2, . . . , n } . It is known that the sum of interior angles of the polygon is solely determined by £». In this thesis, we give an exact formula to calculate the sum of interior angles in term of £». We make use of this formula to derive a recurrence relation concerning the number of star polygons having a particular value of sums of interior angles.

This thesis verified that metric spaces can be constructed using ultrametrics d and D, where d(x,y) = 0 if x = y and d(x,y) = (1/2) k if x not equal to y, such that x-y = 2k(a/b) for a,b relatively prime to 2, and where D(A,B)= max(d(al,bl); d(a2,b2)) for A = (al,a2) and B = (bl,b2).Assuming that a line is represented by some linear equation, a one-dimensional point was defined as an element of Q and a two-dimensional point as an element of Q x Q. There was an investigation of one-dimensional points with respect to the behavior of segments, midpoints, and distances as measured by d. The function D demonstrated the behavior of midpoints, medians, and triangles, as well as the congruence relation. The study necessitated the introduction of pseudomidpoints and pseudomedians, and an unorthodox definition of angle measurement.

Made available in DSpace on 2014-06-11T19:22:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-08Bitstream added on 2014-06-13T19:49:09Z : No. of bitstreams: 1 thomaz_t_me_rcla.pdf: 901888 bytes, checksum: 96e22240a3b1710d26349f35b8551430 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo tem como objetivo definir as orientações dos segmentos envolvidos na ação de chutar, comparar dois tipos de chute - potência e precisão através das variáveis angulares do segmento pelve e das articulações do quadril, do joelho e do tornozelo. A orientação dos segmentos pelve, coxa, perna e pé foi feita através da utilização da convenção dos ângulos de Euler (CHAO, 1980; ZATSIORSKY, 1998), através de rotinas desenvolvidas no software Matlab®. Para obtenção das imagens foram utilizadas 4 câmeras digitais JVC GR-9800u, fixas em tripés, o tratamento das imagens foi realizado no software Dvideow (BARROS et al, 1999; Figueroa et al, 2003). Nos resultados encontrados verificou-se que o segmento pelve apresenta diferença entre os dois tipos de chute no movimento de rotação à direita /esquerda e também no movimento de inclinação lateral direita/esquerda. Durante a realização do chute de precisão a pelve apresenta-se em rotação para a direita de maneira mais acentuada quando comparada ao chute de potência. Diferenças também foram encontradas no movimento de inclinação lateral, a pelve apresenta-se mais inclinada à direita na execução do chute de precisão em relação ao chute de potência. A articulação do quadril apresenta diferenças no movimento de abdução/adução, pois durante o chute de precisão foi verificado o movimento de abdução mais acentuado, e no chute de potência o movimento identificado foi o de adução. O joelho apresenta uma flexão mais acentuada no chute de potência. E a articulação do tornozelo apresenta diferença nos movimentos de dorsiflexão/flexão plantar, durante o chute de precisão o segmento pé está em dorsiflexão devido a vi intenção de acertar a bola com a região medial do pé. Conclui-se que os dois chutes diferem-se nos movimento de rotação à direita/esquerda e inclinação lateral... / The goal of the proposed study is to define the positions and orientations of the segments involved in the action of kicking by females, and to compare the two specific types of kicks: potency and precision using the angular variables . These orientations will be defined by the convention of Euler s angles (CHAO, 1980; ZATSIORSKY, 1998) and through routines developed using the software Matlab®. For obtaining images, four digital cameras (JVC GR-9800u) will be used, fixed on tripods. The processing of the images will be performed using the software Dvideow (BARROS et al, 1999; Figueroa et al, 2003). The results show that the pelvis presents differences in the left/right tilt and in the left/right rotation. The hip shows differences in the abduction/adduction movements, the knee has a flexion movement in the potent kick bigger than in the precision kick, and at the ankle join hasn't been found differences in the pronation/evertion movement.

No description available.

A new control law is being developed and implemented for the Vision Based Target Tracking (VBTT) system onboard a small unmanned aerial vehicle (SUAV). The new control law allows for coordinated SUAV guidance and vision-based target tracking of stationary and moving targets in the presence of atmospheric disturbances and measurements noise. The new control law is tested for its performance and stability in both the theoretical 6DOF simulation and the Hardware-in-the-Loop (HIL) simulation. Principal results show that realistic measures of performance of the control law are continuous and exhibit predictable degradation of performance with increase of target speed. The results are encouraging and comparable among theoretical predictions, actual hardware simulation results, and initial flight testing. The control law development, implementation, and trial processes and procedures are also examined and categorically documented in this thesis as future reference on the subject development, as well as for better knowledge retention, continuation and proliferation of the VBTT system.

Systematic pre cleaning, disinfection and sterilization of medical equipment used in examination and treatment of patients are very important for safe care of the patients and the staff handling these instruments. Due to the technical properties of stainless steel, its hygienic experience and the sophisticated look of the stainless steel, it has dominated the medical health care environments for decades. The wetting properties of stainless steel surfaces are presumed to be essential for the process of clean ability and for a wide variety of bio compatibility.In collaboration with the topical company for this thesis, the idea is to find the correlation between the surface properties of various stainless steel in relation to their wetting and spreading ability to enable efficient cleaning of the surface. For a substrate surface to be thoroughly cleaned of any debris or soil, it should be able to allow proper adherence of the liquid across its surface to a certain degree good enough to ensure good wettability of the surface and conversely easy and proper removal of any attached soil on the surface. Higher demand on cleaning, disinfection and sterilization processes became more and more pressing due the development of complex medical equipment.Different stainless steel (316L) surface finishes and some surgical equipment are investigated using the state of the equipment at Halmstad University. Using the imaging interferometer and mapping software, Mountain Map, the results obtained is controlled readings and classification of the various surface parameters. Contact angle measurements were carried out on each surface with three polar (Distilled water, Glycerol and Ethylene glycol) and one non polar (Olive Oil) probe liquids with a drop volume of 3μm using Theta Optical Tensiometer and One Attention Software for the analysis. The impact and correlations of the surface parameters on wettability was later compared from the measurements obtained.