In this thesis, a methodology for rigid body dynamic modeling and control design is presented for a 6 degree-of-freedom (DOF) parallel-kinematic-mechanism-based reconfigurable meso-milling machine tool (RmMT) with submicron tracking accuracy requirement. The dynamic modeling of the parallel kinematic mechanism (PKM) is formulated using the Lagrangian method with the application of principle of energy equivalence and coordinate transformations to separate the mechanism into serial sub-systems. The rigid body gyroscopic force is also modeled using this approach and its effect as a disturbance is analyzed and compensated. The contour errors for both position and orientation are formulated to increase machining accuracy. The dynamic model of the system is linearized through feedback linearization and the contour error based feedback control law is formulated using the convex combination design approach to satisfy a set of design specifications simultaneously. The dynamic model and its control methodology are simulated and verified within the MATLAB Simulink environment.

This thesis investigates the key determinants of the Non-performing loans (NPLs) comparing two groups of countries from Southeastern and Western Europe, with two different levels of economic development. We try to find empirical evidence and estimate whether the determinants of NPL ratio are different for the middle and high income countries. Applying panel data models for 14 countries overall, and using the regressions of subsampled countries, we analyze the importance of the determinants at the aggregate level. The final results show that all variables considered are significant, except inflation rate under all specifications and FDI when the subsampled dummy variables are used. As for the specifications of the exchange rate determinant, we conclude that the NPL ratio is negatively and significantly influenced in the export dominant middle income economies. An additional non-economic variable, such as the educational index, constructed at the national level, is found to increase the NPL ratio. Concerning the institutional quality index, averaging all six institutional indicators, this determinant does not show a consistent result across different data sample specifications.

In the present thesis we perform modeling of earthquake source using laboratory derive rate-and-state laws of friction. We have developed a code in Fortran 90 for modeling a planar, two-dimensional fault with general dip and heterogeneous distribution of frictional parameters. We use a quasi-dynamic approximation and assume that the fault is submnerged in an infinite elastic half-space. We performed an extensive number of numerical experiments to study the effect of fricitonal parameters distribution on the spatio-temporal complexity of slip on fault. We also study the effect of the so called Coulomb stress changed on clock advance and clock delay of events. For this purpose we use both a homogeneous model and a model of random frictional parameteres which exhibits the Gutenberg-Richter frequency- size dependence in the range of two magnitudes. We find that the effect of Couloumb stress change is nontrivial and depends on factors such as the domain of stress load and the slip velocity on it. Powered by TCPDF (www.tcpdf.org)

"Automatic assembly machines have many cam-driven linkages that provide motion to tooling. Newer machines are typically designed to operate at higher speeds and may need to handle products with small and delicate features that must be assembled precisely every time. In order to design a good tooling mechanism linkage, the dynamic behavior of the components must be considered; this includes both the gross kinematic motion and self-induced vibration motion. Current simulations of cam-follower system dynamics correlate poorly to the actual dynamic behavior because they ignore two events common in these machines: impact and over-travel. A new dynamic model was developed with these events. From this model, an insight into proper design of systems with deliberate impact was developed through computer modeling. To attain more precise representations of these automatic assembly machines, a simplified industrial cam-follower system model was constructed in SolidWorks CAD software. A two-mass, single-degree-of-freedom dynamic model was created in Simulink, a dynamic modeling tool, and validated by comparing to the model results from the cam design program, DYNACAM. After the model was validated, a controlled impact and over-travel mechanism was designed, manufactured, and assembled to a simplified industrial cam-follower system, the Cam Dynamic Test Machine (CDTM). Then, a new three-mass, two-degree-of-freedom dynamic model was created. Once the model was simulated, it was found that the magnitude and the frequency of the vibration, in acceleration comparison, of the dynamic model matched with the experimental results fairly well. The two maximum underestimation errors, which occurred where the two bodies collided, were found to be 119 m/s2 or 45% and 41 m/s2 or 30%. With the exception of these two impacts, the simulated results predicted the output with reasonable accuracy. At the same time, the maximum simulated impact force overestimated the maximum experimental impact force by 2 lbf or 1.3%. By using this three-mass, two-DOF impact model, machine design engineers will be able to simulate and predict the behavior of the assembly machines prior to manufacturing. If the results found through the model are determined to be unsatisfactory, modifications to the design can be made and the simulation rerun until an acceptable design is obtained."

Fault feature analysis of gear tooth spall plays a vital role in gear fault diagnosis. Knowing the characteristic of fault features and their evolution as a gear tooth fault progresses is key to fault severity assessment. This thesis provides a comprehensive (both theoretical and experimental) analysis of the fault vibration features of a gear transmission with progressive localized gear tooth pitting and spalling. A dynamic model of a one-stage spur gear transmission is proposed to analyze the vibration behavior of a gear transmission with tooth fault. The proposed dynamic model considers the effects of Time Varying Mesh Stiffness (TVMS), tooth surface roughness changes and geometric deviations due to pitting and spalling, and also incorporates a time-varying load sharing ratio, as well as dynamic tooth contact friction forces, friction moments and dynamic mesh damping ratios. The gear dynamical model is validated by comparison with responses obtained from an experimental test rig under different load and fault conditions. In addition, several methods are proposed for the evaluation of the TVMS of a gear pair with tooth spall(s) with curved bottom and irregular shapes, which fills the current research gap on modelling tooth spalls with irregular shapes and randomly distribution conditions. Experiments are conducted and the fault vibration features and their evolution as the tooth fault progresses are analyzed. Based on feature analysis, a new health indicator is proposed to detect progressive localized tooth spall.

This report presents the development of a dynamic temperature model for an automatic transmission in a Volvo Cars passenger vehicle. The model should simulate the oil to cooler temperature and flow from the transmission. A mathematical approach to use lumped masses for different parts of the transmission was used. To tune the response of the lumped masses and heat transfer coefficients; temperature measurements were done on a vehicle in a chassis dyno. To verify the model, simple drive cycles were performed with temperature measurement in the same chassis dyno and on the same vehicle. The verification on the model shows that the model can simulate the behavior of a transmission with an error of 2.5 °C during normal behavior and 6.5 °C for a few minutes when a sudden change in the temperature from the cooler have a large transient increase. Because of this, the model is considered to be fairly accurate. However, in order to make the model compatible with Volvo Cars existing simulation software, Vsim, a "cooler model" has to be created.

The ability to obtain deoxyribonucleic acid (DNA) profiles is generally considered a powerful tool when examining evidence associated with a crime scene. However, variability in peak heights associated with short tandem repeats (STR) signal complicates DNA interpretation; particularly, low-template complex mixtures, which are regularly encountered during evidentiary analysis. In order to elucidate the sources that cause peak height variability a dynamic model, which simulates; 1) the serial dilution process; 2) polymerase chain reaction (PCR); and 3) capillary electrophoresis (CE) was built and used to generate simulated DNA evidentiary profiles. In order to develop the dynamic model, PCR efficiencies were characterized. This was accomplished using empirical quantitative polymerase chain reaction (qPCR) data. Specifically, the ratios of fluorescent readings of two consecutive cycles were evaluated. It was observed that the efficiency fluctuated at early cycles; stabilized during the middle cycles; and plateaued during later cycles. The relationship between the change in efficiency and the concentration of amplicons was modeled as an exponential function. Subsequently, this exponential relationship was incorporated into the dynamic model as a part of the PCR module. Using the dynamic laboratory model, the effect of serially diluting a concentrated DNA extract to a low-template concentration was assessed in an effort to determine whether serially diluted samples are a good representation of evidence samples which contain low copy number of cells. To accomplish this, peak height variances and the frequency of drop-out between serially and non-serially diluted samples were compared. The results showed that diluting the sample had a substantial influence on allelic drop-out. However, the distributions of the observed peak heights did not consistently change; though, changes in peak height distributions became more pronounced with samples at lower targets. The peak height equivalency (PHE) was also used to aid in the determination of the effect of serial dilutions on reproducibility. There was not a major change in PHE between serially and non-serially diluted samples.

The choice of reference frames used in simulations is typically fixed in dynamic models based on modeling decisions made early during their development, restricting model fidelity, numerical accuracy and integration into large-scale simulations. Individual simulation components typically need to model the transformations between multiple reference frames in order to interact with other components, resulting in additional development effort, time and cost. This dissertation describes the methods for defining and managing different reference frames in a simulation, thereby creating a shared simulation environment that can provide reference frame transformations, comprising of kinematics and rotations, to all simulation components through a Reference Frame Manager. Simulation components can use this Reference Frame Manager to handle all kinematics and rotations when interacting with components using different reference frames, improving the interoperability of simulation components, especially in parallel and distributed simulation, while reducing their development time, effort and cost. The Reference Frame Manager also facilitates the development of Generic Dynamic Models that encapsulate the core service of dynamic model, enabling the rapid development of dynamic models that can be reused and reconfigured for different simulation scenarios and requirements. The Reference Frame Manager can also be used to introduce Intermediate Frames that bound the magnitudes of vehicle states, reducing roundoff error and improving numerical accuracy.

To identify the dynamic model of the treadmill, this study uses the piezoelectricity material (Po1yviny-lidene fluoride, PVDF) to measure the force under treadmill. With this dynamic model, the ground reaction force (GRF) can be derived from the PVDF sensors. The reliability and precision of the GRF results are verified by replacing the PVDF with the traditional load cell (Force measurement devices). To verify the accuracy of treadmill model, this study acquires three different types of GRF signals (marking time, walking and running) from ten subjects. For the marking time case, the correlation coefficients between the actual and predicated GRF signals are approximately 0.98. This study also demonstrates that the proposed model can provide sufficient bandwidth for the walking and running GRF signals. Finally, via comparing the average GRF profile, inter-personal differences of the GRF signal can be observed. Among the three tested locomotion patterns, the marking time GRF has the highest similarity whereas the running GRF signals has the largest variability.

Precise positioning is crucial for the success of navigation of underwater vehicles. At present, different instruments and methods are available for underwater positioning but few of them are reliable for three-dimensional position sensing of underwater vehicles. Long baseline (LBL) positioning is the standard method for three-dimensional underwater navigation. However, the accuracy of LBL positioning suffers from its own drawback of relatively low update rates. To improve the accuracy in positioning an underwater vehicle, integration of additional sensing measurements in a LBL navigation system is necessary. In this study, numerical simulation and experiment are conducted to investigate the effect of interrogate rate on the accuracy of LBL positioning. Numerical and experimental results show that the longer the interrogate rate, the greater the LBL positioning error. In addition, no reply from a transponder to transceiver interrogation is another major error source in LBL positioning. The experimental result also shows that the accuracy of LBL positioning can be significantly improved by the integration of velocity sensing. Therefore, based on Kalman filter, this study integrates a LBL system with vehicle dynamic model to improve the accuracy of positioning an underwater vehicle. For conducting the positioning experiments, a remotely operated vehicle (ROV) with dedicated Graphic User Interface (GUI) is designed, constructed, and tested. To have a precise motion simulation of ROV, a nonlinear dynamic model of ROV with six degrees of freedom (DOF) is used and its hydrodynamic parameters are identified. Finally, the positioning experiment is run by maneuvering the ROV to move along an ¡§S¡¨ trajectory, and Kalman filter is adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation when the measurements of range, depth, and thruster command are available. The experimental result demonstrates the effectiveness of the integrated LBL system with the ROV dynamic model on the improvement of accuracy of positioning an underwater vehicle.