The high demands on data processing and bandwidth in wireless/wireline communication and aerospace systems have been pushing forward circuit design techniques to their limitations to obtain maximum performances with respect to high operating frequency, low noise, small area, and low power consumption. Clock generators are essential components in numerous circuits, for instance, frequency synthesizers for high speed transceivers, clock sources for microprocessors, noise suppressed zero-delay buffers in system-on-chips (SOCs), and clock and data recovery (CDR) systems. Furthermore, clock generators are required to provide low jitter and high precision clocks in fully integrated image reject receivers and an ultra-wide tunability in time-interleaved applications. We explore several circuit design techniques and implementations of low jitter clock generator in this thesis. Firstly, a low jitter and wide range digital phase-locked loop (DPLL) operating 8 ~ 16 GHz is illustrated using a dual path digital loop filter (DLF). In order to mitigate the phase jitter in the phase detector (PD), we implement the separate loop filter and the output is not affected by the proportional path. For the stable operation, a 4 ~ 8 GHz linear phase interpolator (PI) is implemented in the proportional path. In addition, we design a low phase noise digitally controlled oscillator (DCO) using inductive tuning technique based on switched mutual coupling for wide operating range. The proposed DPLL implemented in 65 nm CMOS technology shows an outstanding figure-of-merit (FOM) over other state-of-art DPLLs in term of root mean square (RMS) and deterministic jitter (DJ). Secondly, we discuss a radiation-hardened-by-design (RHBD) PLL using a feedback voltage-controlled oscillator (FBVCO) in order to reduce DJ due to the radiation attack on the control voltage. Different from a conventional open loop VCO, the proposed FBVCO has a negative control loop and is composed of an open loop VCO, an integrator and a switched-capacitor resistor. Since the input to output of the FBVCO has a low-pass characteristic, any disturbance on the control voltage should be filtered and cannot affect the output phase. We are able to reduce the output frequency variation approximately 75% compared to the conventional PLL when the radiation pulse strikes on the control voltage. The proposed RHBD PLL is implemented in 130 nm and consumes 6.2 mW at 400 MHz operating frequency. Thirdly, a novel adaptive-bandwidth PLL is illustrated to optimize the jitter performance in a wide operating frequency range. We achieve a constant ratio of bandwidth and reference frequency with a closed loop VCO and an overdamping system with a charge pump (CP) current proportional to the VCO frequency for the adaptive-bandwidth technique. The proposed adaptive-bandwidth PLL presents 0.6% RMS jitter over the entire frequency range from 320 MHz to 2.56 GHz, which is 70% smaller than the conventional fixed-bandwidth PLL. Finally, we have developed a new feedback DCO to achieve a linear gain of DCO so that the DPLL can provide stability and a wide operating range in different process variations. Due to the negative feedback loop of the proposed DCO, the feedback DCO presents a linear gain from an input digital word to an output frequency. Moreover, we can control the bandwidth of the feedback DCO to optimize the total output phase noise in DPLL. In simulation, we can obtain 17 MHz/LSB of the peak-to-peak gain of the feedback DCO, which is reduced 96% over the conventional DCO.

O objetivo principal desse trabalho é investigar a aplicação de cerâmica á base de Zirconia em ferramentas de corte na usinagem de aço temperado (VND) utilizando um torno de ultraprecisão. Foram analisados dois tipos de composições de cerâmicas com estrutura cristalina diferentes, sendo elas: monoclínica e tetragonal. A diferença destas estruturas é devido à adição de Ytria. A fase monoclínica não contém Ytria em sua composição, enquanto, a fase tetragonal é obtida com Ytria (\'Y IND.3\') (chamada zirconia parcialmente estabilizada com Ytria). A fase tetragonal apresenta uma resistência elevada ao impacto junto com alta dureza (1800 kgf/\'MM POT.2\') quando comparada com a fase monoclínica que apresenta alta dureza mas menor tenacidade. Devido a este fato, esses materiais têm chamado à atenção dos pesquisadores para a usinagem de aços endurecidos. A geração de superfície é influenciada por diversos fatores, sendo eles: material peça, condições de corte, erros macro geométrico, erros de micro geometricos e do estado da aresta da ferramenta. Na usinagem de ultraprecisão a alta rigidez e vibração/trepidação máquina ferramenta é usada para evitar erros de micro geometria e macro geometria que conseqüentemente são transferidos para superfície da peça. Neste trabalho, devido ao fato de se usar um torno de ultraprecisão é possível afirmar que o perfil da rugosidade é gerado pela replicação do perfil da aresta da ferramenta de corte para a superfície da peça. A rugosidade da superfície foi medida com um perfilometro óptico com resolução de 0,1 nm. Os resultados mostraram que a rugosidade da superfície obtida após os testes de usinagem com as ferramantas de cerâmicas chegou á valores em torno de 0,140 microns, o que equivale ao acabamento com processo de retificação. Outro aspecto importante refere-se ao desgaste das ferramentas que, conseqüentemente, tem uma grande influência nos resultados obtidos. As ferramentas de corte foram analisadas antes e depois da usinagem por microscópio eletrônico de varredura. Verificou-se que as ferramentas de corte na fase tetragonal apresentaram desgaste do tipo cratera na aresta da ferramenta enquanto a aresta da ferramenta monoclínica apresentou desgaste do tipo lascamento. / The main objective of this work is to investigate the application of a ceramic composite of Alumina-Zirconia cutting tools inserts in the machining of hardened steel (VND) in an ultraprecision lathe. Two different ceramic compositions with different crystalline structure were tested, to know: monoclinic and tetragonal. The difference in these structures is due the addition of Yttrium. The monoclinic phase has no Yttrium in its composition while the tetragonal phase is obtained with Ytrium (\'Y IND.3\') (named partially stabilized zirconium). The tetragonal phase presents a high impact toughness along with high hardness (1800 kgf/\'MM POT.2\') when compared to the monoclinic phase which presents high hardness but lower toughness. Due to this fact, these materials have draw attention of researchers in the field of machining of hardened steels. The surface generation is influenced by several factors, to know: workpiece material, cutting conditions, macro geometry errors, micro geometry errors and the sharpness of the cutting edge. In ultraprecision machining, a high stiffness and chatter/vibration free machine tool is used in order to avoid common macro and micro geometry errors replicated into the workpiece surface. In this case, it is possible to assert that the roughness profile is generated by the replication of the cutting tool edge profile to the workpiece surface. The surface roughness was measured by an optical profiler with resolution of 0,1 nm. The results showed that the surface roughness obtained after machining tests with these ceramic inserts were in the range of 0,140 micrometers, which is in the same range of roughness obtained by the grinding process. Another important aspect refers to the wear of the ceramic inserts which has direct influence in the performance as a cutting tool material. The cutting inserts were evaluated before and after machining by scanning electron microscope. It was found that the tetragonal phase cutting tools presented crater wear on the rake face while the monoclinic phase presented cutting edge chipping as the main main type of wear.

L‟élimination de certains déchets est un enjeu important en Côte d‟Ivoire. Une des solutions proposée est d‟envisager l‟utilisation de ces déchets comme granulats dans les bétons. Les travaux présentés dans ce document portent sur l‟incorporation de quatre différents déchets.La première étude porte sur un béton confectionné avec trois types de déchets : du verre concassé, du ciment durci concassé et des pneus découpés. Elle a été réalisée en deux phases. Dans la première ces déchets ont été incorporés à du béton pour remplacer 100% des graviers (substitution totale). Dans la seconde une substitution (massique) partielle de gravier a été réalisée dans les proportions suivantes 5, 10, 15, 20, 25 et 30 %, la matrice mortier et le rapport eau-ciment restant identiques. Après une maturation de 28 jours leurs résistances en compression ont été déterminées. Ces résultats montrent que les bétons de recyclât ont une résistance inférieure à celui des bétons de concassé de gravier. Toutefois, la résistance mécanique baisse avec l‟augmentation de la substitution. Une loi donnant la résistance en fonction du taux de recyclât a été établie. De plus, la spécificité des granulats de caoutchouc (résistance à la fissuration) est remarquée.Par ailleurs, les résistances des bétons de recyclât ont permis d‟établir une loi donnant la résistance en fonction des caractéristiques des agrégats et de leur fraction volumique. Une modélisation analytique a été proposée pour prédire la résistance des bétons en fonction de la taille et du volume des granulats recyclés.Les granulats issus du concassage des bétons frais (retour de toupie) utilisés comme substituant des granulats naturels a été menée pour évaluer leur potentiel. Un plan d‟expériences statistique à deux variables (% de recyclât dans le sable et % de recyclât dans le gravier) a été utilisé pour réduire le nombre de mesures. Les proportions de remplacement utilisées sont : 0%, 50% et 100%. Les propriétés mécaniques ont été déterminées par différentes méthodes destructives (résistance à la compression et à la traction) et non destructives (ondes ultrasonores pour évaluer l‟élasticité du matériau). De même, les propriétés physiques telles que la porosité accessible à l‟eau, la masse volumique ont été mesurées. Ces résultats montrent une bonne corrélation entre le pourcentage de remplacement et les propriétés physiques et mécaniques de ce béton / Waste management is an important issue for Côte d‟Ivoire. Among many possibilities, recycling wastes as aggregates for concrete is a solution that deserves to be evaluated. In this study four recycled aggregates are tested: crushed glass, tire cut rubber, hardened cement and fresh concrete waste. There properties are compared to those of natural aggregates.A first study is realized in Côte d‟Ivoire on glass, rubber and hardened cement. Concrete is realized and tested in compression (cylindrical 16x32 specimens). A mix with an increasing quantity of coarse aggregates is tested for each recycled material (20 %, 25 %, 30 % and 50 % in mass of fine and coarse aggregates). It is shown that the strength decreases with the replacement rate and that the decrease depends on the replacing material. The materials ranged in the following increasing order: rubber, glass, hardened cement and natural aggregates. A power law is established which gives the compressive strength as function of the mix and the materials characteristics. Analytical modeling was proposed for predincting the strength with respect to recycled aggregates size and volume.Another experiment is also made on glass and rubber, where partial replacement in increasing percentage is tested. Natural aggregates are partially replaced in the mix with the ranges of 5, 10, 20, 25 and 30 % by rubber and glass. The compressive strength is determined and a decrease is observed for the two materials. In the case of rubber a high decrease in observe with the replacement. In the case of glass a decrease occurs between 0 and 5 % replacement then the strength remains constant with the replacement rate. The third experiment is made with partial replacement of fresh recycled concrete (excess of ready-mixed concrete from concrete mixing plant which is hardened and then crushed). A plan of experiments is made which allows a polynomial law to be drawn giving the strength as a function of the recycled proportion. Other properties (Young modulus, P wave velocity, porosity, density, etc) have been determined and their relation with replacement rate computed.

O objetivo principal desse trabalho é investigar a aplicação de cerâmica á base de Zirconia em ferramentas de corte na usinagem de aço temperado (VND) utilizando um torno de ultraprecisão. Foram analisados dois tipos de composições de cerâmicas com estrutura cristalina diferentes, sendo elas: monoclínica e tetragonal. A diferença destas estruturas é devido à adição de Ytria. A fase monoclínica não contém Ytria em sua composição, enquanto, a fase tetragonal é obtida com Ytria (\'Y IND.3\') (chamada zirconia parcialmente estabilizada com Ytria). A fase tetragonal apresenta uma resistência elevada ao impacto junto com alta dureza (1800 kgf/\'MM POT.2\') quando comparada com a fase monoclínica que apresenta alta dureza mas menor tenacidade. Devido a este fato, esses materiais têm chamado à atenção dos pesquisadores para a usinagem de aços endurecidos. A geração de superfície é influenciada por diversos fatores, sendo eles: material peça, condições de corte, erros macro geométrico, erros de micro geometricos e do estado da aresta da ferramenta. Na usinagem de ultraprecisão a alta rigidez e vibração/trepidação máquina ferramenta é usada para evitar erros de micro geometria e macro geometria que conseqüentemente são transferidos para superfície da peça. Neste trabalho, devido ao fato de se usar um torno de ultraprecisão é possível afirmar que o perfil da rugosidade é gerado pela replicação do perfil da aresta da ferramenta de corte para a superfície da peça. A rugosidade da superfície foi medida com um perfilometro óptico com resolução de 0,1 nm. Os resultados mostraram que a rugosidade da superfície obtida após os testes de usinagem com as ferramantas de cerâmicas chegou á valores em torno de 0,140 microns, o que equivale ao acabamento com processo de retificação. Outro aspecto importante refere-se ao desgaste das ferramentas que, conseqüentemente, tem uma grande influência nos resultados obtidos. As ferramentas de corte foram analisadas antes e depois da usinagem por microscópio eletrônico de varredura. Verificou-se que as ferramentas de corte na fase tetragonal apresentaram desgaste do tipo cratera na aresta da ferramenta enquanto a aresta da ferramenta monoclínica apresentou desgaste do tipo lascamento. / The main objective of this work is to investigate the application of a ceramic composite of Alumina-Zirconia cutting tools inserts in the machining of hardened steel (VND) in an ultraprecision lathe. Two different ceramic compositions with different crystalline structure were tested, to know: monoclinic and tetragonal. The difference in these structures is due the addition of Yttrium. The monoclinic phase has no Yttrium in its composition while the tetragonal phase is obtained with Ytrium (\'Y IND.3\') (named partially stabilized zirconium). The tetragonal phase presents a high impact toughness along with high hardness (1800 kgf/\'MM POT.2\') when compared to the monoclinic phase which presents high hardness but lower toughness. Due to this fact, these materials have draw attention of researchers in the field of machining of hardened steels. The surface generation is influenced by several factors, to know: workpiece material, cutting conditions, macro geometry errors, micro geometry errors and the sharpness of the cutting edge. In ultraprecision machining, a high stiffness and chatter/vibration free machine tool is used in order to avoid common macro and micro geometry errors replicated into the workpiece surface. In this case, it is possible to assert that the roughness profile is generated by the replication of the cutting tool edge profile to the workpiece surface. The surface roughness was measured by an optical profiler with resolution of 0,1 nm. The results showed that the surface roughness obtained after machining tests with these ceramic inserts were in the range of 0,140 micrometers, which is in the same range of roughness obtained by the grinding process. Another important aspect refers to the wear of the ceramic inserts which has direct influence in the performance as a cutting tool material. The cutting inserts were evaluated before and after machining by scanning electron microscope. It was found that the tetragonal phase cutting tools presented crater wear on the rake face while the monoclinic phase presented cutting edge chipping as the main main type of wear.

L’objectif de ces travaux de thèse est l’optimisation par une approche expérimentale d’un modèle de micro-fraise hémisphérique en carbure de tungstène revêtu, de diamètre 0,5 mm, destiné à l’usinage des aciers durs. Les données expérimentales obtenues résultent donc de l’usinage d’un acier 40NiCrMo16 à l’état trempé (54 HRC). Les résultats permettent de mettre en évidence certains phénomènes de coupe, d’usure et de comportement dynamique de l’outil liés au procédé, et leur évolution en fonction du type de fraise considéré et des conditions de coupe choisies. La géométrie de l’outil et son comportement dynamique sont ici principalement commentés. Dans un premier temps, l’étude de différentes nuances de carbure, préparation de surface ainsi que l’optimisation des géométries globale et locale des micro-fraises a permis de proposer un modèle optimisé pour notre partenaire outilleur Magafor. Dans un second temps, une approche numérique du micro-fraisage a été utilisée. Un premier modèle de calcul analytique des efforts de coupe a été testé et il a été mis en évidence les limites d’identification des coefficients spécifiques de coupe dans notre cas. Ensuite, une modélisation numérique par éléments finis du micro-fraisage a été réalisée afin d’appréhender l’étude du comportement dynamique des micro-fraises en fonction de la géométrie globale de l’outil développé. / The aim of this PhD work is optimized by experimental approach with 0.5 mm diameter micro-ball-end mills made from micro-grain tungsten carbide and PVD coated for hardened tool steels machining. The experimental data are obtained on machining of hardened steel (54/55HRC), typically used for the production of plastic injection molds. Results permit to highlight some cutting phenomena of wear and dynamic behavior of the process related tool, and changes depending on the type of milling considered and selected cutting conditions. The geometry of the tool and dynamic behavior are primarily discussed here. As a first step, the study of different carbide grades, surface preparation and optimization of global and local geometries of micro-cutters helped provide an efficient model for our partner Magafor toolmaker. In a second step, the modelling of micro-milling is discussed and an analytical model for cutting forces calculation is introduced. It was demonstrated the identifying limits of the specific cutting coefficients in our case. Then, a test of finite element modelling of micro-milling is made in order to estimate the potential of such a method for the study of the dynamic behaviour of micro-mills.

Atlas Copco Secoroc AB are searching after new bulk materials for drill heads that are used in percussive drilling in order to improve their strength and durability. The aim of this project is to assist Atlas Copco in this search and provide them with further information regarding material properties, alloying elements, suppliers, etc. A literary study was carried out in order to identify materials that had UTS and KIC more than or equal to 1700 MPa and 70 MPa*m^1/2, respectively. Materials that fulfilled these criteria were T250 grade maraging steel, Cobalt free maraging steel, High cobalt maraging steel, 300 grade maraging steel, AerMet 100, AF1410, S53, M54, 300M, 4340M and PremoMet. These were categorized into maraging steels, high alloy secondary hardened steels, and low alloy steels, and were then further researched. The material with the highest combination of UTS and KIC was M54 followed by AerMet 100; while AF1410 had the highest KIC but a low UTS, and PremoMet had the highest UTS but a low KIC. Maraging steels and HASH steels have a similar price range, while low alloy steels are much cheaper.

The thesis is focused on machining of hard-to-machine materials. In the theoretical part hard-to-machine materials are divided and characterized. Furthermore, the thesis specifies hardened steels and their heat treatment, machinability and mechanism of wear and chip formation. There are tool materials and their classes suitable for machining hardened steels. The practical part deals with the influence of the cutting conditions on the roughness of the machined surface when turning hardened steel.

The thesis deals with the wear of replaceable inserts during the turning of structural hardened steel. The theoretical part describes a brief characteristic of turning technology, force loading on tools and tools used in turning. Moreover, it contains an analysis of the chemical composition of the machined material, its microstructure and microhardness. Machines and equipment used for the experiment and their specifications. The experimental part of the thesis describes the method of measuring and evaluating of tool wear, followed by the cutting tests themselves, documenting of the result and their evaluation. The conclusion of the thesis is the processing of measured data, the evaluation of achieved results and the proposal of further steps to improve the process.

The Master‘s thesis focuses on processing of hard-to-machine materials by the finishing machining methods. The first chapter comprises division and characteristics of finishing technologies in the field of machining processes. The chapter following includes division and characteristics of the hard-to-machine materials. The experimental part – another significant part of the thesis – is focused on grinding of mostly bearing rings made of hard-to-machine materials. The aim of the experimental part is to compare and subsequently assess the use of various kinds of grinding wheels in the grinding process of a given workpiece material. Several parameters are examined from the technological and economic point of view. The assessment of the experimental part provides an overview on the advantages and disadvantages of the use of the grinding wheels in the grinding process of a given material for large-scale production. The conclusion is a summary of the results obtained in the experimental part.

This thesis focuses on the verification of physical and mechanical characteristics of hardened concrete, especially concrete compressive strength, static and dynamic modulus of elasticity. The job description is to perform a series of laboratory analyzes for structural concrete and evaluate the test results meet requirements that are specified in the European standards for designing buildings. The work also includes selected techniques for risk assessment (FMEA, Pareto diagram, Ishikawa diagram) and their application to selected process. Part of the work is also a static comparison of measured characteristics and consideration of the risks associated with variations in the monitored quantities.