The northwest part of the North America-Caribbean plate boundary zone is characterized by active, left-lateral strike-slip faults that are well constrained seismically and are corroborated by on- and offshore geologic mapping. The onshore plate boundary zone comprises the Motogua and Polochic fault systems of southern Guatemala which join and continue offshore as the Swan Islands fault zone along the southern edge of the Cayman trough. At the Mid-Cayman spreading center in the central Caribbean Sea, the fault motion is transferred at a 100 km wide left-step in the fault system to the Oriente fault zone. A third system, the Walton fault zone, continues east from the Mid-Cayman Spreading center to define the Gonave microplate. Seafloor features produced by strike-slip faulting along the Swan Islands and Walton fault zones have been imaged and mapped using the SeaMARC II side-scan sonar and swath bathymetric mapping system, single-channel seismic data, multichannel seismic data and 3.5 kHz depth profiles. Structures mapped along the Swan Islands and Walton fault zones include: 1) twenty-six restraining bends and five releasing bends ranging in size from several kilometers in area to several hundred kilometers in area; 2)en echelon folds which occur only within the restraining bends; 3) straight, continuous fault segments of up to several tens of kilometers in length; 4) restraining and releasing bends forming in "paired" configurations; and 5) a fault-parallel fold belt fold and thrust belt adjacent to a major restraining bend. The features observed along the Swan Islands and Walton fault systems are compared to other features observed along other strike-slip fault systems, from which empirical models have previously been derived. Based on the features observed in these strike-slip systems, a rigid plate scenario is envisioned where the geometry of the fault and the direction of plate motion have controlled the types of deformation that have occurred. In a related study, microtectonic features in an area of Neogene extension within the northwestern Caribbean plate were investigated in order to provide insight on the nature of intraplate deformation related to the motion along the plate boundary. Microtectonic features were measured in the Sula-Yojoa rift of northwestern Honduras with the intention of inverting the data to estimate stress states responsible for the observed strains. Data inversion for the estimation of stress states could not be undertaken with the available measurements, however, the observations made can be used to support several existing models for the intraplate deformation as well as to encourage the elimination of other models. / text

Traction efficiency of tractors barely reaches 50 % in field operations. On the other hand, modern trends in agriculture show growth of the global tractor markets and at the same time increased demands for greenhouse gas emission reduction as well as energy efficiency due to increasing fuel costs. Engine power of farm tractors is growing at 1.8 kW per year reaching today about 500 kW for the highest traction class machines. The problem of effective use of energy has become crucial. Existing slip control approaches for tractors do not fulfil this requirement due to fixed reference set-point. The present work suggests an optimal control scheme based on set-point optimization and on assessment of soil conditions, namely, wheel-ground parameter identification using fuzzy-logic-assisted adaptive unscented Kalman filter.

This paper presents an open system architecture with wireless network centric telemetry and data acquisition over UDP/IP. This networked solution was designed and developed for iron bird and helicopter rotor applications which present a significant challenge for data acquisition and telemetry. Traditionally slip rings were used for data transfer however these result in issues with low bandwidth, electrical noise, installation complexity, and high maintenance costs. This paper describes a networked system using standardized technologies and protocols that was used for data acquisition and recording of parameters such as vibration, strain, and video on DAQ installed on the rotating part. The acquired data was transmitted in real-time via the network-centric wireless telemetry link which was synchronized with a ground-based DAQ used for real time processing of the rotor data.

We first describe the methodology for a two-dimensional, elastic deformable microplate modeling approach for continental plate boundaries. Deformable microplate models combine discrete slip on microplate boundaries (faults) with continuous deformation in block interiors. Two idealized models simulating continental collision are presented, one with two microplates and one with four microplates. / Earth and Planetary Sciences

Current literature focusing on the prosthetic socket is limited by measurement techniques and modeling assumptions, leading to a limited understanding of the forces and motions occurring between the residual limb and prosthesis and how they can be used to influence socket design and fitting. Prosthetic socket fitting and prescription would benefit from an elegant method for comparing socket designs. This dissertation focuses on the development and implementation of a 3D motion capture model and a Slip Detection Sensor to quantify rotations and translations at the prosthetic socket-residual limb interface. The 3D motion capture model defines the residual limb bone position inside the prosthetic socket which allows for measurement of the movement occurring at the prosthetic socket interface. The Slip Detection Sensor is an optoelectronic sensor embedded into the prosthetic socket wall to measure the amount of socket slip occurring between the socket wall and the residual limb skin surface. The motion capture model and Slip Detection Sensor were used to measure motion at the socket interface of transhumeral amputees during activities of daily living. Data were collected on six transhumeral amputees in the University of South Florida's (USF) motion analysis laboratory. One of the participants completed the collection procedures twice using two different suspension systems (pin locking versus no pin locking) within the same socket. An eight camera Vicon (Oxord, UK) motion capture system was used to collect kinematic data for each participant during the repetition of a series of range of motion (RoM) and activities of daily living (ADL). The RoM tasks included shoulder flexion/extension, shoulder abduction/adduction, shoulder rotation, and elbow flexion. The ADL tasks included a bilateral and unilateral lifting task at various weight increments, modified box and blocks test, folding a towel, and walk and carry a gallon jug of water. The impact of donning the prosthesis on the participant's RoM and the amount of socket movement during the ADL tasks was analyzed. The results show that the participant's shoulder RoM significantly decreased while wearing their prosthesis compared to when they were not wearing their prosthesis. The anterior-posterior tilt, medial-lateral tilt, and socket vertical translation were more directly correlated with the amount of residual limb movement than with the force acting on the prosthetic hand. Socket slip was most directly correlated with the force acting on the prosthetic hand. The results also show that the amount of translation was reduced when the pin locking suspension was used compared to when it wasn't for the individual participant who used both suspension systems within the same socket. The motion capture data were used to determine the amount of socket movement during activities of daily living while avoiding many of the limitations of other socket interface studies. The Slip Detection Sensor provided experimental data on the amount of slip occurring between the residual limb skin surface and socket wall. This method seems to be a useful tool for evaluating socket performance in terms of movement. Ultimately, socket interface movement data can be used to providing clinicians with quantitative results of a good socket fit to aid in the socket fitting and prescription process and incorporated into adjustable interfaces. Collection of data on more participants with various socket types is needed to make more general conclusions.

This thesis is addressed to the understanding of the mechanisms at the origin of the contact wave fields at frictional interfaces and its relationship with the local characteristics of the surfaces in contact, as well as with the global dynamics and macroscopic frictional behaviour of the system. The aim of this work is to provide insights on the generation and propagation of the waves through the contact both to avoid instabilities and to control their effect on friction. The work is organized in two main parts. The first part presents the development of a non-linear finite element analysis in large transformations of the dynamic rupture at the interface with contact friction separating two bodies (isotropic and elastic) without relative motion. A rupture is considered when an initially sticking zone shifts in sliding state. The properties of the obtained ruptures are analyzed for a flat interface between dissimilar materials in function of the nucleation energy; then the effect of the interface roughness is analyzed. The differentiated rupture inside the asperities and the conditions for coupling and uncoupling between the waves radiating in the two bodies have been also investigated. In the second part, the analysis deals with the sliding onset between two bodies in contact. The sliding between two bodies made of different isotropic elastic materials and separated by a frictional interface is simulated. The evolution along the time of the global normal and tangential forces is analyzed, relating it to the local phenomena occurring at the interface. This part tries to investigate how micro-slips at the interface, acting as distributed ruptures, trigger the macro-slips between the two bodies. The interaction between local and global dynamics is also studied. Finally a numerical parameter space study is carried out, as a function of several system parameters (contact law, friction coefficient, material damping, normal load, translational velocity and regularization time). The results show the key role of the micro-slips and precursors (detectable wave propagations that occur at tangential global force well below the critical value expected by the friction law) in triggering the macro-slip between the two bodies. Depending on their distribution and magnitude the evolution of the contact forces passes from stick-slip-like behaviour to continuous sliding. The local dynamics at the contact (wave and rupture propagation) is linked to the global behaviour of the system (stick-slip, continuous sliding, induced vibrations); the effect of the contact and system parameters on the transfer of vibrational energy between the sliding contact and the system is investigated. The numerical results obtained by the two parts of the work show a good agreement with experimental results in literature.

Les pieds d'aubes de soufflantes de turboréacteurs font face à des sollicitations de type fretting. Il en résulte deux types d'endommagements: (i) l'amorçage et la propagation de fissures, (ii) l'usure des surfaces en contact. OBJECTIF: Afin de fournir les outils permettant de répondre à la problématique industrielle, une méthode semi-analytique permettant de traiter des problèmes de contacts élasto-plastiques revêtus et/ou hétérogènes est développé à partir d'éléments existants et de solutions analytiques et numériques novatrices. METHODE: La structure est simplifiée en supposant un contact entre deux massifs élastiques semi-infinis. Des solutions analytiques donnant pour: + les contributions élémentaires de chargements normaux et tangentiels constants sur une surface rectangulaire + les contributions élémentaires de déformations plastiques supposées constantes sur un volume parallélépipédique + les contributions élémentaires de déformations d'incompatibilité liées à un problème hétérogène (inclusions, revêtements, endommagement,...) supposées constantes sur un volume parallélépipédique. >> les déplacements en surface ou les contraintes dans le volume. Les déplacements en surface ou les contraintes dans le volume sont alors exprimés en utilisant des produits de convolution discrets entre des coefficients d'influence et la source surfacique (chargements en surface) ou volumique (déformations plastiques ou d'incompatibilité). Le problème normal et le problème tangentiel en glissement total ou en glissement partiel peuvent alors être résolus, en prenant en compte les effets plastiques et hétérogènes. L'algorithme d'optimisation sous contrainte utilisé (contact elastique) est celui développé par L.Gallego tandis que la base du solver plastique utilisé a été développé par C. Jacq (contact elasto-plastique sans frottement) RESULTATS: De nouvelles solutions analytiques sont obtenues pour le calcul des déplacements résiduels tangentiels.

As the depth of mining increases, so does the risk of fault slip related rockbursts. Currently, there is no way to evaluate this risk, however the need for such a system is clear. Fault behaviour in mining environments is the result of a complex interaction between the mining system and the geological system. Although numerous models exist, the wide spectrum of fault behaviour cannot be fully explained. Additionally, these models are phenomenological, resulting in a disconnect between observable parameters and the models of faults. Fault behaviour is dependent upon the strength of the fault, the stresses acting along the fault, the boundary conditions and fault-system stiffness. Significant work exists in the field of earth science attempting to relate properties of the geological system to fault behaviour. In mining environments, these relationships become increasingly difficult to determine due to the time variable nature of mining activities. In order of importance, the following factors influence fault behaviour: excavations, tectonic history and in situ stress, fault system, fault zone geometry, pore pressure, fault zone slip surface and core, blasting, fault zone damage zone and wall rock and temperature. Numerical stress analysis models were created to evaluate the influence of excavations, tectonic history and in situ stress and the fault system on fault behaviour. Excavations were placed in various locations in a fault system. Results showed that there was no clear relationship between excavation location and fault behaviour; small perturbations in the initial state caused significantly different outcomes. The architectures of many classification and decision support systems were evaluated for purposes of a fault slip classification system. Due to the chaotic nature of fault behaviour and the time variable nature of the factors that influence fault slip, a typical classification system is not an appropriate architecture. Instead, it is recommended that a fault slip risk identification system be created, allowing for the incorporation of historical and live data to create a real time response. Artificial neural networks, numerical stress analysis, data from the identified important factors, and seismic data is recommended to form the basis of the fault slip risk identification system. / Thesis (Master, Mining Engineering) -- Queen's University, 2012-06-01 13:17:08.453

The rotor shaft of a synchronous machine can experience severe mechanical stress due to torque pulsations during a pole-slip condition. All pole-slip protection relays currently on the market use the impedance pole-slip protection method to detect a pole-slip. No commercial relay currently available can predict accurately when a generator is about to experience a damaging pole-slip. All the relays will only trip a generator after it has pole-slipped one or more times. Severe mechanical damage could be caused to a machine after only one pole-slip. It is therefore essential to enhance pole-slip protection relays to such an extent that it can trip a generator before it pole slips. The proposed pole-slip protection function must predict when a generator will become unstable during a network fault. As soon as instability is predicted, the generator must be tripped before the fault is cleared to avoid damaging post-fault torque effects. Conventional impedance pole-slip protection methods are are also discussed and the shortcomings of impedance pole-slip protection are investigated. The new pole-slip protection function was designed by using PSCAD. Detailed PSCAD simulations on different network configurations proved that the new pole-slip protection function will trip a generator before a damaging pole-slip occurs. The new pole-slip protection function was also implemented on an ABB REM543 multifunctional protection relay and tested on a RTDS. The concept of the new pole-slip function was successfully demonstrated on the protection relay. The operation of conventional impedance scheme relays was compared with the proposed pole-slip function for different fault conditions. Although the new pole-slip protection function is more complex than the existing impedance functions, it was concluded that similar skills are required to test and commission the new protection function. The new pole-slip function outperforms the impedance protection methods, since the new protection function can trip the generator before it pole-slips. / PhD (Electrical Engineering), North-West University, Potchefstroom Campus, 2011

The rotor shaft of a synchronous machine can experience severe mechanical stress due to torque pulsations during a pole-slip condition. All pole-slip protection relays currently on the market use the impedance pole-slip protection method to detect a pole-slip. No commercial relay currently available can predict accurately when a generator is about to experience a damaging pole-slip. All the relays will only trip a generator after it has pole-slipped one or more times. Severe mechanical damage could be caused to a machine after only one pole-slip. It is therefore essential to enhance pole-slip protection relays to such an extent that it can trip a generator before it pole slips. The proposed pole-slip protection function must predict when a generator will become unstable during a network fault. As soon as instability is predicted, the generator must be tripped before the fault is cleared to avoid damaging post-fault torque effects. Conventional impedance pole-slip protection methods are are also discussed and the shortcomings of impedance pole-slip protection are investigated. The new pole-slip protection function was designed by using PSCAD. Detailed PSCAD simulations on different network configurations proved that the new pole-slip protection function will trip a generator before a damaging pole-slip occurs. The new pole-slip protection function was also implemented on an ABB REM543 multifunctional protection relay and tested on a RTDS. The concept of the new pole-slip function was successfully demonstrated on the protection relay. The operation of conventional impedance scheme relays was compared with the proposed pole-slip function for different fault conditions. Although the new pole-slip protection function is more complex than the existing impedance functions, it was concluded that similar skills are required to test and commission the new protection function. The new pole-slip function outperforms the impedance protection methods, since the new protection function can trip the generator before it pole-slips. / PhD (Electrical Engineering), North-West University, Potchefstroom Campus, 2011