Comprehensive knowledge and information about the static and dynamic behaviour of machine tools, cutting processes and their interaction is essential for machining system design, simulation, control and robust operation in safe conditions. The very complex system of a machine tool, fixture and cutting tools during the machining of a part is almost impossible to model analytically with sufficient accuracy. In combination with increasing demands for precision and efficiency in machining call for new control strategies for machining systems. These strategies need to be based on the identification of the static and dynamic stability under both the operational and off-operational conditions. To achieve this it is necessary to monitor and analyze the real system at the factory floor in full production. Design information and operational data can then be linked together to make a realistic digital model of a given machining system. Information from such a model can then be used as input in machining simulation software to find the root causes of instability. The work presented in this thesis deals with the static and dynamic capability of machining systems. The main focus is on the operational stability of the machining system and structural behaviour of only the machine tool, as well. When the accuracy of a machining system is measured by traditional techniques, effects from neither the static stiffness nor the cutting process are taken into account. This limits the applicability of these techniques for realistic evaluation of a machining system’s accuracy. The research presented in this thesis takes a different approach by introducing the concept of operational dynamic parameters. The concept of operational dynamic parameters entails an interaction between the structural elements of the machining systems and the process parameters. According to this concept, the absolute criterion of damping is used to evaluate the dynamic behaviour of a machining system. In contrast to the traditional theory, this methodology allows to determine the machining system's dynamic stability, in real time under operating conditions. This framework also includes an evaluation of the static deformations of a machine tool.  In this context, a novel concept of elastically linked system is introduced to account for the representation of the cutting force trough an elastic link that closes the force loop. In addition to the elastic link which behaves as a static element, a dynamic non-contact link has been introduced. The purpose is to study the non-linear effects introduced by variations of contact conditions in joints due to rotational speed. / QC 20111123

This master´s thesis is focused on chosen dynamic parameters of a sport vehicle represented by student formula Dragon 7 and comparison of these parameters with conventional vehicles represented by two exemplars of ŠKODA Superb III. Driving tests used for the comparison are simulating the real driving situations from the roads in order to possibly use those for the road accident analysis in the future. All the measurements were taken under lower adhesion conditions which might help solving of the road accidents under such conditions in the future. There is also a description of vehicle driving systems and components which have an influence on the vehicle´s driving dynamics incorporated in the thesis.

In terms of deciding on the appropriate use of the railway superstructure assemblies in both the recommendations arising from the theoretical analysis (modeling), as well as recommendations obtained under static and dynamic testing of the finished product play an important role. Such tests can then be applied in the laboratory or in the field. The thesis will be devoted to operational testing of selected track grid structures in situ. For measurement purposes an appropriate measuring point will be chosen and the methodology of measurement will be proposed. In terms of track geometry sections in curves will be selected. On the basis of tests carried out dynamic parameters of structures will be determined. To their evaluation suitable mathematical system will be chosen. It assumes the use of mathematical methods in time and frequency areas. In the thesis there will also be a comparison of the parameters of the tested structures. Based on the measurements it will be a source of recommendations for the practice.

Pervasive applications of the vehicle simulation technology are a powerful motivation for the development of modern automobile industry. As basic parameters of road vehicle, vehicle dynamic parameters can significantly influence the ride comfort and dynamics of vehicle, and therefore have to be calculated accurately to obtain reliable vehicle simulation results. Aiming to develop a general solution, which is applicable to diverse test rigs with different mechanisms, a novel model-based parameter identification approach using optimized excitation trajectory is proposed in this paper to identify the vehicle dynamic parameters precisely and efficiently. The proposed approach is first verified against a virtual test rig using a universal mechanism. The simulation verification consists of four sections: (a) kinematic analysis, including the analysis of forward/inverse kinematic and singularity architecture; (b) dynamic modeling, in which three kinds of dynamic modeling method are used to derive the dynamic models for parameter identification; (c) trajectory optimization, which aims to search for the optimal trajectory to minimize the sensitivity of parameter identification to measurement noise; and (d) multibody simulation, by which vehicle dynamic parameters are identified based on the virtual test rig in the simulation environment. In addition to the simulation verification, the proposed parameter identification approach is applied to the real test rig (vehicle inertia measuring machine) in laboratory subsequently. Despite the mechanism difference between the virtual test rig and vehicle inertia measuring machine, this approach has shown an excellent portability. The experimental results indicate that the proposed parameter identification approach can effectively identify the vehicle dynamic parameters without a high requirement of movement accuracy.

En la práctica profesional de la ingeniería civil, generalmente, se consideran los componentes del movimiento del suelo de forma independiente y desestimando la componente vertical en los análisis sísmicos. Sin embargo, ya existen estudios que invalidan dichos supuestos, y, es por tal, que el análisis sísmico debería considerar el efecto de todas las componentes del sismo a fin de estimar cualquier respuesta en la estructura. En este estudio se propondrán factores de amplificación para los espectros generados por los análisis uni-direcconales, con el fin de extenuar el efecto tri-direccional del sismo. Dichos factores se realizarán por medio del análisis de 54 estructuras caracterizadas por distintos parámetros dinámicos. Y, además, utilizando ángulos de incidencia cada 10° y 11 registros sísmicos para el ATH. Las respuestas máximas se compararán con las del espectro propuesto por la Norma E0.30 [1], obteniendo así reglas lineales para los factores de amplificación. / In the professional practice of civil engineering, generally, the components of the ground movement are considered independently and disregarding the vertical component in seismic analyzes. However, there are already studies that invalidate these assumptions, and, therefore, the seismic analysis should consider the effect of all the components of the earthquake in order to estimate any response in the structure. In this study, amplification factors will be proposed for the spectra generated by the uni-directional analyzes, in order to exhaust the tri-directional effect of the earthquake. Said factors will be carried out through the analysis of 54 structures characterized by different dynamic parameters. And, in addition, using incidence angles every 10 ° and 11 seismic records for the ATH. The maximum responses will be compared with those of the spectrum proposed by Standard E0.30, thus obtaining linear rules for the amplification factors. / Trabajo de investigación

Dans les régions néo-tropicales, l’augmentation des taux de changements d’occupation et d’usages des sols et une forte déforestation durant la deuxième moitié du 20e siècle ont engendré une forte dégradation de l’environnement et une forte perte de biodiversité. Cette étude analyse les empreintes spatiales et les processus des changements d’occupation et d’usages des sols et de la déforestation pour le bassin versant du Grijalva-Usumacinta, l’un des plus importants du sud Mexique en matière hydrologique et de biodiversité, pour être confrontée aux discussions sur les changements forestiers émergents. Des cartes d’occupation et d’usages des sols de 1992, 2002 et 2007, dérivées d’images satellitaires et de photographies aériennes sont utilisées pour tester l’hypothèse d’un changement de trajectoires d’évolution à l’échelle régionale. Les probabilités et taux de changements ont été calculés pour les deux périodes 1992-2002 et 2002-2007, et les processus de changements dominants ont été identifiés. Les changements d’occupation et d’usages des sols sont complexes et ne peuvent s’expliquer par une histoire prédominante et linéaire de la déforestation. Deux des principaux résultats concernent (1) un taux anormalement élevé de dégradation des forêts primaires, équivalent à 1,7 fois la surface déforestée ; (2) les processus de déforestation se produisent principalement dans les forêts secondaires. Les activités agricoles, encouragées par les politiques publiques, sont les principaux moteurs de ces changements, parmi lesquelles le pâturage a le plus d'impact sur la déforestation. Les probabilités et taux de déforestation et de changement d’occupation et d’usages de sols ont stagné alors que la reforestation naturelle a augmenté. Bien que ces tendances sont essentielles pour le commencement de la transition forestière, la déforestation et la dégradation l'emportent bien sur la repousse de la végétation. / This study explores how to use techniques of prospective analysis in order to incorporate dynamic factors that put into risk the persistence of biodiversity into systematic conservation planning. Land use and cover change (LUCC) and climate change (CC) represent the main impacts and future threats to biodiversity and thus were the subject of analyses that provided information on prioritization for conservation actions. Since LUCC, CC and biodiversity loss, as well as the related socio-economic structures take place on a regional scale, this work is based on a large watershed in southern Mexico, the Grijalva-Usumacinta Basin. This basin is not only one of the most important areas for biological diversity, but is also renowned for its cultural complexity and hydrological importance and the multiple environmental and social problems that put biodiversity in peril. The main finding is that deforestation and forest degradation are the main LUCC processes and their high rates and strong future trends make it difficult to get to the point of forest transition in the near future, when deforestation and regeneration are balanced. Nevertheless, the scenario analysis shows that it is possible to influence LUCC trajectories in a substantial way in order to halt negative effects over biodiversity in the next decade. CC represents an additional threat to biodiversity difficult to evaluate, especially if the multiple synergistic effects between CC and LUCC are considered that could lead to much higher impacts. Anyway, the analysis showed that even until 2030 CC could have impacts on bioclimatic variables and species composition that could further hamper conservation efforts in the study area. Criteria for a proactive prioritization of sites for conservation are proposed based on scenarios of LUCC and CC. These criteria are used to identify “hot spots” (high probability of LUCC and severe CC impacts) and “refuges” (high probability of permanence and minor CC impacts). This joint analysis of CCUS and CC shows that there are differences between the conservation and the probable scenario; the effort needed to conserve the biodiversity contained in the priority sites in the conservation scenario is considerable less. The spatial pattern of hot spots and refuges of change is very similar across scenarios, despite the differences in absolute areas compromised by each. / Este estudio explora cómo aplicar técnicas de análisis prospectivos para incorporar factores dinámicos que ponen en riesgo la persistencia de biodiversidad en la planeación sistemática de la conservación (PSC). El cambio de cobertura y uso del suelo (CCUS) y el cambio climático (CC) representan los impactos y amenazas futuras más importantes para la biodiversidad, por lo que fueron escogidos como sujetos de análisis que proveen información para la priorización para acciones de conservación. Como el CCUS, el CC, la pérdida de biodiversidad, así como las estructuras socio-económicas relacionadas, ocurren a una escala regional, este trabajo está basado en una cuenca grande en el sur de México. La cuenca Grijalva-Usumacinta no sólo es una de las áreas más biodiversas en el mundo, también es reconocida por su complejidad cultural y su importancia hidrológica. A la vez se han documentado diversos problemas ambientales y sociales que ponen en peligro la persistencia de la biodiversidad. El resultado principal es que la deforestación y la degradación forestal son los procesos dominantes de CCUS y sus altas tasas y fuertes tendencias hacia el futuro vuelven difícil de llegar al punto de la transición forestal, en el cual la deforestación y la regeneración son balanceadas. Sin embargo, el análisis de escenarios muestra que es posible influenciar las trayectorias de CCUS de manera sustancial para detener los efectos adversos en la biodiversidad en la próxima década. El CC representa una amenaza adicional para la biodiversidad difícil de evaluar, especialmente si se consideran los múltiples efectos sinérgicos entre el CC y el CCUS que podrían hacer que el impacto sea mucho mayor. Aun así, el análisis mostró que hasta el 2030 el CC podría tener impactos en las variables bioclimáticas y la composición de especies que podrían dificultar más los esfuerzos de conservación en el área de estudio. Se proponen criterios para una priorización proactiva de la conservación son propuestos basados en escenarios de CCUS y CC. Estos criterios son usados para identificar focos rojos (alta probabilidad de CCUS e impactos de CC severos) y refugios (alta probabilidad de permanencia natural e impactos de CC menores). Este análisis conjunto de CCUS y CC muestra que hay diferencias entre el escenario de conservación y el escenario probable; el esfuerzo necesario para conservar la biodiversidad dentro de los sitios prioritarios es considerablemente menor. Los patrones espaciales de los focos rojos de cambio y los refugios son muy similares en los dos escenarios, a pesar de la diferencia absoluta de áreas en cada uno.

1. The method for automatic digital balancing of Wheatstone resistance bridge was developed and investigated using DAC R-2R matrix for evaluation of resistance small changes. Balancing method enables reducing of external influence impact to evaluation results and avoids most disadvantages that are common to classic systems based on unbalanced Wheatstone bridge. The parameters of connecting wires and channel switches are not impacting evaluation results in the system developed. Advantages of the system developed are proven by experiments. System developed allows low cost implementation of systems for evaluation of resistance small changes. 2. Possibilities for simplification of circuit for resistance small changes evaluation by using digital signal processing means are proven. It is established that by using known and the proposed methods for improvement of reliability of evaluation results resolution of the evaluation is 12–14 bits (0,024 % - 0,006 % accuracy). It is established that it is necessary to use digital signal processing methods for achieving such resolution. 3. New structures of resistance small change evaluation systems ensuring resolutions of 212 and 28 intended for laboratory investigations and monitoring of constructions are proposed. Experimental model of system with resolution of 28 was made and investigated. Methods of reducing noises in long cables were established during experiment. In general it was proven that the model is suitable for monitoring tasks... [to full text]

Une nouvelle méthode de test pour les convertisseurs ADC et DAC embarqués dans un système complexe a été développée en prenant en compte les nouvelles contraintes affectant le test. Ces contraintes, dues aux tendances de design de systèmes, sont un nombre réduit de point d'accès aux entrées/sorties des blocs analogiques du système et une augmentation galopante du nombre et des performances des convertisseurs intégrés. La méthode proposée consiste à connecter les convertisseurs DAC et ADC dans le domaine analogique pour n'avoir besoin que d'instruments de test numériques pour générer et capturer les signaux de test. Un algorithme de traitement du signal a été développé pour discriminer les erreurs des DACs et ADCs. Cet algorithme a été validé par simulation et par expérimentation sur des produits commercialisés par NXP. La dernière partie de la thèse a consisté à développer de nouvelles applications pour l'algorithme.

This diploma thesis deals with the theoretical description of interference methods used to measure vibrations, examines main parasitic effects and analyses its contribution to achievable the resolution. In the practical part, it uses several measurements to verify the effects of the level of reflected beam, stand-off distance and speckle noise. It also proposes a practical experiment for measuring dynamic parameters and signal-noise ratio. Results show that, the noise is exponentially dependent on the level of the reflected beam. The visible maximum of the vibrometer proved to be critical in terms of time stability of the measured signal level in two of the three measurements. Results of the dynamic measurement show that, the measured deviations were not degraded or significantly disturbed by the noise signal. From the measurement of the speckle noise, it emerged that the lowest level of noise is achieved with smooth and highly reflective materials.