The primary purpose of this thesis was to assess the effect of knee-joint angle on the neuromechanics of maximal and explosive contractions, specifically torque and neuromuscular activation, as well as the influence of isometric resistance training (RT) on these variables and thus joint angle specificity of training adaptations. It was found that electrode location had a pronounced effect on surface electromyography (sEMG) amplitude during maximum isometric voluntary contractions (MVCs) and moderate relationship between subcutaneous tissue thickness and sEMG amplitude (R2=0.31 up to 0.38) was reduced but not consistently removed by maximal M-Wave (MMAX) normalization [up to R2= 0.16 (peak-to-peak) and R2= 0.23 (Area)]. Thus, MMAX peak-to-peak was the better normalization parameter that removed the influence of electrode location and substantially reduced the influence of subcutaneous tissue thickness. Maximal torque-angle relationship presented an inverted U shape with both, agonist (measure by two different techniques) and antagonist neuromuscular activation both differing with knee-joint angle and thus, both likely contributing to the torque-angle relationship. Absolute explosive torque-angle relationship exhibited higher torques at mid-range knee joint angles in a similar manner to maximal strength, whilst the ability to explosively express the available torque (i.e. relative to maximal strength) revealed only subtle differences between joint angles. Agonist neuromuscular activation showed increases from extended to flexed positions during both maximum and explosive contractions (at all time points; ~6% to ~34%) and evoked contractile properties presented opposite patterns with twitch torque increasing (~5% to ~30%) and octet torque decreasing (~2% to ~14%) with knee flexion. Finally, after 4 weeks of RT at a 65° knee-joint angle evidence of joint angle specificity was provided from both within-group (greater gains at 3 angles than others) and between-group evidence (greater gains at 2 angles than others) for maximal strength but not for explosive strength and neuromuscular activation. In summary, this thesis demonstrated: (1) higher strength values at middle knee-joint positions than more flexed and/or extended positions during maximal and explosive contractions; (2) how agonist neuromuscular activation contributes to the beforementioned changes in strength; (3) how muscle contractile properties contribute to the explosive strength across knee-joint angles; and finally (4) that joint angle specificity has a neural basis.

O objetivo deste estudo foi investigar o efeito do erro na localização do centro de pressão (5 e 10 mm) nas incertezas de momentos articulares dos membros inferiores em diferentes velocidades de marcha (1,0, 1,5 e 2,0 m/s). Nossas hipóteses foram que: as incertezas absolutas de momento articular diminuam de distal para o proximal e da condição de maior para a de menor velocidade. Os momentos articulares de cinco adultos jovens saudáveis foram calculados pelo método bottom-up de dinâmica inversa 3D, na dependência do qual estimamos as incertezas propagadas. Os resultados indicaram que existe uma relação diretamente proporcional entre os erros do centro de pressão e as incertezas de momento articular. As incertezas absolutas nos picos de momento expressas no sistema de referência anatômico diminuíram de distal para proximal, confirmando nossa primeira hipótese, exceto para o momento de abdução. Da menor para a maior velocidade de marcha ocorreu um aumento da incerteza no momento (de até 0,04 Nm/kg), confirmando agora nossa segunda hipótese, exceto, mais uma vez, para abduções de joelho e quadril. E ainda, as incertezas relativas variaram dependendo do plano e articulação (entre 5 e 31%), sendo os momentos articulares de joelho os mais afetados / The aim of this study was to investigate the effect of errors in the location of the center of pressure (5 and 10 mm) on lower limb joint moment uncertainties at different gait velocities (1.0, 1.5, and 2.0 m/s). Our hypotheses were that the absolute joint moment uncertainties would be gradually reduced from distal to proximal joints and from higher to lower velocities. Joint moments of five healthy young adults were calculated by inverse dynamics using the bottom-up approach, depending on which estimate the uncertainty propagated. Results indicated that there is a linear relationship between errors in center of pressure and joint moment uncertainties. The absolute moment peak uncertainties expressed on the anatomic reference frames decreased from distal to proximal joints, confirming our first hypothesis, except for the abduction moments. There was an increase in moment uncertainty (up to 0.04 Nm/kg for the 10 mm error in the center of pressure) from the lower to higher gait velocity, confirming our second hypothesis, although, once again, not for hip or knee abduction. Finally, depending on the plane of movement and the joint, relative uncertainties experienced variation (between 5 and 31%), and the knee joint moments were the most affected

Este trabalho apresenta um método de estimativa de torque do joelho baseado em sinais eletromiográficos (EMG) durante terapia de reabilitação robótica. Os EMGs, adquiridos de cinco músculos envolvidos no movimento de flexão e extensão do joelho, são processados para encontrar as ativações musculares. Em seguida, mediante um modelo simples de contração muscular, são calculadas as forças e, usando a geometria da articulação, o torque do joelho. As funções de ativação e contração musculares possuem parâmetros limitados que devem ser calibrados para cada usuário, sendo o ajuste feito mediante a minimização do erro entre o torque estimado e o torque medido na articulação usando a dinâmica inversa. São comparados dois métodos iterativos para funções não-lineares como técnicas de otimização restrita para a calibração dos parâmetros: Gradiente Descendente e Quasi-Newton. O processamento de sinais, calibração de parâmetros e cálculo de torque estimado foram desenvolvidos no software MATLAB®; o cálculo de torque medido foi feito no software OpenSim com sua ferramenta de dinâmica inversa. / This work presents a method for knee torque estimation based on electromyographic signals (EMG) during robotic rehabilitation therapy. EMG, taken from five muscles acting during flexion and extension movements of the knee joint, are processed to get the muscle activations. Then, through a simple model of muscle contraction, the forces are computed and knee torque estimated using the joint geometry. Muscle activation and muscle contraction functions have bounded parameters to be adjusted for each user. This adjustment is made by minimizing the error between the estimated torque and the measured torque in the joint computed via inverse dynamics. Two iterative methods for constrained nonlinear optimization are compared, escending Gradient and Quasi-Newton. Signal processing, parameters calibration and estimated torque calculation are developed in the MATLAB® software. Measured torque calculation is performed on OpenSim software using the dynamic inverse tool.

This thesis aims to design and develop LSPM motors capable of operating in two distant synchronous speeds with good starting torque and steady state characteristics for variety of industrial applications, in particular offshore and maritime applications. The proposed designs are based on variable pole numbers for the stator and the rotor. The stator winding consist of two independent windings with different pole numbers to switch the winding and change the operating pole count for low and high speed applications. For the motor to operate in these two distinct operating speeds, the rotor must be capable of creating two different magnetic polarities (pole numbers) to adapt itself to the stator operating pole number. For this purpose, two different schemes for the rotor structure are proposed. In scheme I two-speed operation is realized by the combination of electromagnetic torque and reluctance torque which enables the motor to operate as a synchronous PM motor at high speed and synchronous reluctance motor at low speed. In scheme II, rotor with dual PM polarity is proposed which enables the motor to operate as a PM motor at both low and high speed regions.

The motivation of this research is to explore the viability of a method to directly verify whether or not an anaerobic adhesive within a threaded fastener assembly has cured sufficiently to provide secondary locking. Direct verification was implemented via the application of a test torque in the loosening direction of a fastener assembly with Loctite (given a 24 hour cure time). A three phase test plan was developed with the intent of identifying and utilizing this verification torque value which is unique to a given fastener assembly. It was proved that the direct verification method, as outlined in the test plan, was in fact a valid method of verification in some cases. Results were dependent on the materials and coatings of the fastener assemblies. The curing properties of the liquid locking compound (LLC) with plain steel specimens resulted in a verification test that could accurately predict sufficient locking and cure (using distributions in torque measurements). Tests with zinc coated and stainless steel specimens, however, did not produce the same level of predictability in cure as the plain steel specimens. The direct verification method as defined herein is not suited to certain materials and coatings. The less predictable curing properties of the stainless steel specimens caused complications in determining a verification torque that could reliably determine cure, resulting in dropping stainless steel from static and dynamic testing. The zinc coated specimen data was more consistent, but the adhesive did not add sufficient breakaway strength to the fastener assembly needed to define a usable verification value. These results led to the conclusion that the direct verification method as presented in this work is limited to more active material selections. One possibility to improve the secondary locking of less active materials is the use of a higher strength adhesive. Testing to observe the effect of application of verification torque on the secondary locking was also performed. Multiple verifications were found to be destructive to the point that just over a third of samples failed that might have otherwise passed a single verification test. The single verification testing, on the other hand, caused substantially less locking mechanism degradation, leading to the use of a single verification torque in further testing.

The purpose of this research is to determine if anaerobic adhesive can be used as a prevailing torque locking feature. Maintaining preload in critical joints is the usual standard that anaerobic adhesives are held to in aerospace and other industry. To test if anaerobic adhesive can be used as a prevailing torque locking feature a test procedure was developed and implemented to measure the removal torque of threaded fasteners after an allotted cure time. In total, 191 threaded fasteners of different material and coatings were tested in the unseated and seated states with various strengths and varieties of anaerobic adhesive. A series of three tests were conducted: initial use, reuse with no added anaerobic adhesive, and a third test with added product to the bolt and nut to see how removal torque would behave in these conditions. It was found that using anaerobic adhesive as a prevailing torque locking feature is viable in many cases. No published work to date analyzes anaerobic adhesive at the standard of a prevailing torque locking feature.

The manufacturing of nanocontact-based spin-torque oscillators (NC-STOs)has opened the door for spintronic devices to play a part as active microwaveelements. The NC-STO has the capability of converting a direct current intoa microwave signal, and vice versa, by utilizing the spin transfer torque (STT)in ferromagnetic multilayer systems. However, the high-frequency operation ofNC-STOs typically requires high magnetic fields and the microwave power theygenerate is rather limited. As a result, NC-STOs are not yet commercially used,and they require improvements in both material systems and device geometriesbefore they can find actual use in microwave applications. In order to improve and advance this technology, NC-STOs are requiredwith both different nanocontact (NC) sizes and geometries, and using differ- ent stacks of magnetic materials. This dissertation presents experimental in- vestigations into the manufacturing of such devices using different fabrication techniques and a number of different magnetic material stacks. Currently, the fabrication of NC-STOs is limited to advanced laboratories, because NC fabri- cation requires high-resolution lithography tools. In the present work, we have developed an alternative method of fabrication, which does not require such tools and has the capability of fabricating NC-STOs having one to hundreds of NCs in a variety of sizes, possibly  down to 20 nm. Devices fabricated with this method have shown mutual synchronization of three parallel-connected NCs, and pairwise synchronization in devices with four and five NCs. Furthermore, the present work demonstrates low-field operation (down to0.02 Tesla) of NC-STOs at a record high frequency of 12 GHz. This wasachieved by implementing multilayers with a perpendicular magnetic anisotropy(PMA) material in the free layer of the NC-STO. In addition, the fabricateddevices revealed an unexpected dynamic regime under large external appliedfield (above 0.4 Tesla). The new dynamic regime was found to be due to anentirely novel nanomagnetic dynamic object â a so-called magnetic droplet soliton,predicted theoretically in 1977 but not experimentally observed until now.Detailed experiments and micromagnetic simulations show that the droplet hasvery rich dynamics. Finally,  spin-torque-induced  transverse spin wave instabilities have beenstudied.  A NC-STO with  a material stack consisting of a single ferromag- netic metal sandwiched between two non-ferromagnetic metals was fabricated. Prior to this work, evidence of spin wave instabilities was reported as resis- tance switching in nanopillar- and mechanical point contact based STOs. In the present  work, the fabricated NC-STOs showed actual microwave  signals up to 3 GHz under zero applied field with strong current hysteresis. All  the fabricated NC-STOs open up new means of studying STT in different environ- ments, in order to resolve their current drawbacks for industrial applications. / <p>QC 20130527</p>

Orientador: Luís Geraldo Vaz / Resumo: A proposta deste estudo foi analisar o comportamento mecânico e a distribuição de forças de diferentes geometrias de ápice em implantes cilíndricos por meio de método de elementos finitos (MEF), fotoelasticidade, torque de inserção e frequência de ressonância. Foram usinados quatro tipos de implantes: sem corte apical (A), com corte apical bi-partido (B), corte apical tri-partido (C), corte apical quadri-partido (D) e um quinto (grupo controle) implante Titamax Ti Ex (Neodent, Curitiba, Paraná, Brasil) (E), todos com dimensões (4,1 X 11,0 mm) de plataforma hexagonal externa. Para o ensaio fotoelástico, blocos de acrílico (30X30X10mm) com um implante foram copiados com Borracha Silicone. Dentro de cada molde de silicone foi vertido resina fotoelástica semi-fexível. Para o ensaio fotoelástico duas situações foram simuladas: aplicação de carga axial de 1 kgf e em outro momento aplicação do torque de 10 N.cm. As fotografias realizadas no polariscópio circular foram transferidas para um computador para leitura dos parâmetros fotoelásticos no software powerpoint (Office 2010). Para o estudo de elementos finitos, o desenho dos implantes foram reproduzidos em CAD (computer Aided design) através do software Autodesk Inventor® (versão 2015, São Paulo, Brasil) e o bloco ósseo tipo IV de dimensões (2X2X2cm) foram posteriormente processados pelo software Rhinoceros v5.0 SR8 (McNeel North America, Seattle, WA, USA). As simulações foram executadas pelo software (Ansys Workbench 10.0, Swanso... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The purpose of this study was to analyze the mechanical behavior and force distribution of five different implant designs using finite element method (FEM), photoelasticity, insertion torque and resonance frequency of different geometric modifications proposed for the apex region Of cylindrical implants. Four types of implants were machined: without apical cut (A), with a two-part apical cut (B), apical tri-split cut (C), apical cut quadri-split (D) and fifth group was composed by Titamax Ti Ex Neodent all with dimensions (4.1 X 11.0 mm). For the photoelastic test, acrylic blocks (30X30X10mm) with implant installed were copied with Blue ASB-10 Silicone Rubber (Polipox). Inside each silicone mold was poured semi-flexible photoelastic resin (Polipox). A titanium UCLA prosthetic intermediate was screwed onto the implant and a dental crown on (Ni-Cr) was fixed on the set. For the photoelastic test two situations were simulated: application of axial load of 1 kgf and torque of 10 N.cm. The photograph and the reading of the photoelastic parameters were performed in a circular polariscope. For the finite element study, the computerAided design (CAD) implants and a Type IV human bone block of dimensions (2X2X2cm) were processed by the software Rhinoceros v5.0 SR8 (McNeel North America, Seattle, WA, USA) At the Renato Archer Information Technology Center (CTI, Campinas, São Paulo - Brazil). The mechanical properties of the implant (titanium grade II) and normal bone type IV were obtai... (Complete abstract click electronic access below) / Doutor

Continuous design and improvements in performance of roller bearings have resulted in an increased power transmission whilst size and spatial requirements have been reduced. Radial cylindrical roller bearings have followed this trend and due to their high performance characteristics (such as high loading capacity and high rotational speed capabilities), they have obtained a firm place as high performance machine elements. An essential characteristic of a radial cylindrical roller bearing is the minimisation of frictional torque for particular operating conditions. In spite of these improvements in design and operation the bearing frictional torque is still usually calculated according to the Palmgren method first published in 1957. However, as a result of the increased performance of radial cylindrical roller bearings and a corresponding wider range of application this Palmgren method is insufficiently accurate for the prediction of frictional torques in modern bearings. Whilst the literature review in this thesis identified a variety of bearing frictional torque calculation methods, most of these methods are based on various ball bearing designs and are not necessarily applicable to cylindrical roller bearings types. As a result an accurate frictional torque prediction method is required for radial cylindrical roller bearings because of customer's demands. Consequently, the current project is combined with the development of a method of frictional torque prediction (FTP - Method), which enables the frictional torque of purely radially and radially and axially loaded radial cylindrical roller bearings to be calculated accurately. The FTP - Method is based on the physical effects producing the frictional torque in a bearing, such as the EHL - theory and a contact analysis to determine raceway rolling resistance, and in addition takes into account the frictional forces of the rib / rolling element end face rolling and sliding contact. Comprehensive experimental tests have been undertaken on different radial cylindrical roller bearing designs (including cage guided and full complement types) for a minimum of three different sizes to validate the derived equations. Good agreement was obtained between the predictions according to the FTP - Method and the measured test data for the frictional torqye of both radially and combined loaded bearings. Moreover, the thermal reference speed and the thermal limiting speed of a radial cylindrical roller bearing can be readily calculated for any operating condition using an explicit equation in the radial part of the FTP - Method. The thesis also presents a calculation program to illustrate a method of bearing design based on the thermal balance within a bearing. The bearing is initially pre-selected according to its life time requirements using a life time calculation. After the lubrication method has been defined a thermal balance can be used to design the bearing.

A osteoartrite de joelho caracteriza-se por um processo degenerativo da cartilagem articular e do osso subcondral, com a presença de processo inflamatório, dor, rigidez, fraqueza muscular, e que leva a uma incapacidade funcional. É uma doença degenerativa e incapacitante, e que necessita de reabilitação funcional para a melhora do indivíduo. Nos casos mais avançados, pode ser realizada a substituição da articulação degenerada por uma prótese. A cirurgia de artroplastia total de joelho pode levar o indivíduo a uma melhora funcional (redução da dor, com conseqüente melhora da capacidade de ativação do quadríceps por redução da inibição muscular reflexa, e possivelmente aumento na capacidade de produção de força do músculo) e a uma melhora da qualidade de vida. Em função disso o objetivo do presente estudo foi comparar as razões de torque e de ativação muscular dos flexores e extensores do joelho e a qualidade de vida e a dor entre indivíduos com osteoartrite de joelho (n=20) e indivíduos com artroplastia total de joelho (n=13). As razões de torque e de ativação dos músculos flexores e extensores de joelho foram avaliados durante contrações isométricas voluntárias máximas no ângulo de 60º, e contrações isocinéticas concêntricas e excêntricas nas velocidades de 60º/s e 180º/s. As razões de torque foram calculas a partir da divisão do valor do pico de torque flexor pelo extensor, e as razões de ativação da mesma forma, porém pela divisão do valor RMS do sinal EMG do músculo BF pelo valor RMS (Root Mean Square) dos músculos VL, RF e VM. As razões musculares foram comparadas entre os grupos e correlacionadas com o questionário Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Os escores do WOMAC e a dor (obtida através da escala visual analógica de dor) foram comparados entre os dois grupos. O grupo artroplastia obteve menores escores no WOMAC quando comparado ao grupo osteoartrite (p=0,022), o que indica melhora da qualidade de vida após a artroplastia total de joelho. O grupo artroplastia também apresentou menor intensidade de dor que o grupo osteoartrite (p=0,014). Tanto as razões de torque quanto as de ativação foram semelhantes entre os grupos. Uma correlação positiva foi encontrada entre as razões de torque isocinético convencional e o WOMAC para o grupo osteoartrite, nas velocidades de 60º/s (r=0,501 p=0,025) e 180º/s (r=0,863 p=0,0001). Isso demonstra que indivíduos com aumento das razões de torque, ou seja, maiores desequilíbrios musculares, apresentaram piora da qualidade de vida. Os resultados deste estudo apoiam a hipótese de que a técnica cirúrgica de artroplastia total de joelho propicia uma redução da dor e uma melhora da qualidade de vida. No entanto, não produz uma melhora na funcionalidade do sistema neuromuscular conforme demonstrou a análise das razões de torque e de ativação dos músculos flexores e extensores do joelho. / The knee osteoarthritis is characterized by a degenerative process of the joint cartilage and of the subcondral bone, with an inflammatory process, pain, joint stiffness, muscular weakness, leading to functional incapacity. It is a degenerative disease, which incapacitates the individual and needs functional rehabilitation. In the most advanced cases, the replacement of the joint is accomplished by the surgical implantation of a prosthesis. The total knee replacement surgery leads the patient to functional improvement (reduction of the pain, increasing muscle force production capacity, and possibly improvement the muscle unbalance) and an improvement of the quality of life. Therefore, the purpose of this study was to compare the muscle torque ratios and the activation ratios of the knee flexor and extensor muscles, as well as the quality of life and the pain intensity amongst patients with knee osteoarthritis (n =20) and patients with total knee replacement (n =13). The torque and activation ratios of the flexor and extensor muscles were evaluated during maximal voluntary isometric contractions at a knee joint angle of 60º, and during maximal voluntary isokinetic contractions (concentric and eccentric) at the angular velocities of 60º/s and 180º/s. The torque ratios were calculated by dividing the maximal peak torque value of the knee flexor muscles by the corresponding knee extensors torque value. The activation ratios were calculated in a similar way, by dividing the RMS values of the biceps femoris muscle by the RMS (Root Mean Square) values of the knee extensor muscles (i.e. vastus lateralis, rectus femoris and vastus medialis). All ratios (torque and activation) were compared between the two groups and correlated with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. The activation ratios showed a similar behavior as the torque ratios for all four muscles studied, and there was no difference for these ratios between the two groups. The WOMAC scores and the pain scores (obtained by the pain visual analog scale) were compared between the two groups. The total knee replacement group obtained smaller scores in WOMAC when compared to the osteoarthritis group (p =0,022). This indicates improvement in the quality of life after the total knee replacement surgery. Patients from the total knee replacement group also presented smaller pain than the osteoarthritis group (p =0,014). A positive correlation was observed between the conventional isokinetic torque ratios and the WOMAC for the osteoarthritis group at the angular velocities of 60º/s (r=0,501 p =0,025) and 180º/s (r =0,863 p =0,0001). This indicates that patients with increased torque ratios, or in other words larger muscular unbalances, also present worsening of the quality of life. The results here presented support the idea that the total knee replacement produces a reduction in pain and an improvement in the quality of life. However, it does not improve the knee functionality as the torque and activation ratios of the knee flexor and extensor muscles was similar between the two groups.