Studio e sviluppo di tecniche per la produzione di nanocompositi a matrice di alluminio

Foundry aluminum alloys play a fundamental role in several industrial fields, as they are employed in the production of several components in a wide range of applications. Moreover, these alloys can be employed as matrix for the development of Metal Matrix Composites (MMC), whose reinforcing phases may have different composition, shape and dimension. Ceramic particle reinforced MMCs are particular interesting due to their isotropic properties and their high temperature resistance. For this kind of composites, usually, decreasing the size of the reinforcing phase leads to the increase of mechanical properties. For this reason, in the last 30 years, the research has developed micro-reinforced composites at first, characterized by low ductility, and more recently nano-reinforced ones (the so called metal matrix nanocomposite, MMNCs). The nanocomposites can be obtained through several production routes: they can be divided in in-situ techniques, where the reinforcing phase is generated during the composite production through appropriate chemical reactions, and ex situ techniques, where ceramic dispersoids are added to the matrix once already formed. The enhancement in mechanical properties of MMNCs is proved by several studies; nevertheless, it is necessary to address some issues related to each processing route, as the control of process parameters and the effort to obtain an effective dispersion of the nanoparticles in the matrix, which sometimes actually restrict the use of these materials at industrial level. In this work of thesis, a feasibility study and implementation of production processes for Aluminum and AlSi7Mg based-MMNCs was conducted. The attention was focused on the in-situ process of gas bubbling, with the aim to obtain an aluminum oxide reinforcing phase, generated by the chemical reaction between the molten matrix and industrial dry air injected in the melt. Moreover, for what concerns the ex-situ techniques, stir casting process was studied and applied to introduce alumina nanoparticles in the same matrix alloys. The obtained samples were characterized through optical and electronic microscopy, then by micro-hardness tests, in order to evaluate possible improvements in mechanical properties of the materials.

Silicon Photonics Integrated Circuits for Flexible Optical Systems

This dissertation deals with the design and the characterization of novel reconfigurable silicon-on-insulator (SOI) devices to filter and route optical signals on-chip. Design is carried out through circuit simulations based on basic circuit elements (Building Blocks, BBs) in order to prove the feasibility of an approach allowing to move the design of Photonic Integrated Circuits (PICs) toward the system level. CMOS compatibility and large integration scale make SOI one of the most promising material to realize PICs. The concepts of generic foundry and BB based circuit simulations for the design are emerging as a solution to reduce the costs and increase the circuit complexity. To validate the BB based approach, the development of some of the most important BBs is performed first. A novel tunable coupler is also presented and it is demonstrated to be a valuable alternative to the known solutions. Two novel multi-element PICs are then analysed: a narrow linewidth single mode resonator and a passband filter with widely tunable bandwidth. Extensive circuit simulations are carried out to determine their performance, taking into account fabrication tolerances. The first PIC is based on two Grating Assisted Couplers in a ring resonator (RR) configuration. It is shown that a trade-off between performance, resonance bandwidth and device footprint has to be performed. The device could be employed to realize reconfigurable add-drop de/multiplexers. Sensitivity with respect to fabrication tolerances and spurious effects is however observed. The second PIC is based on an unbalanced Mach-Zehnder interferometer loaded with two RRs. Overall good performance and robustness to fabrication tolerances and nonlinear effects have confirmed its applicability for the realization of flexible optical systems. Simulated and measured devices behaviour is shown to be in agreement thus demonstrating the viability of a BB based approach to the design of complex PICs.

KNOWLEDGE-BASED MANUFACTURING STRATEGY AND METHODS FOR FOUNDRIES

The European foundry business is a traditional less RTD intensive industry which is dominated by SMEs and which forms a significant part of Europe’s manufacturing industry. The efficient design and manufacturing of cast components and corresponding tooling is a crucial success factor for these companies. To achieve this, information and knowledge around the design, planning and manufacturing of cast components needs to be accessible in a fast and structured way.

A política fundiária do governo Olívio Dutra no Rio Grande do Sul - Brasil (1999-2002): diretrizes, dinâmica política e resultados atingidos

This paper has as objective to analyze the foundry work politics made by the Olívio Dutra's government in the state of Rio Grande do Sul-Brazil, being taken into account their guidelines, the dynamics of the political struggle promoted between the social leaders from the rural area and the achieved global results. This government's freshness is related to the fact of it was being sustained and supported by a coalition of left wing parties and by a group of social movements and also by syndical entities of the field, which was decisive in the presentation of an antagonistic program to the neoliberal politics on energy in a national extent. Hence this government became committed in adopting an own foundry work politics, being opposed to the program of market land reform extolled by Cardoso's government, in national wide. Therefore, the results presented along the article demonstrate that in spite of the assumed commitments and, in face of legal, institutional and economical limitations and also its existent politics, the space of the state governments' performance can only be thought about its complemental character on the federal government's actions.

A política fundiária do governo Olívio Dutra no Rio Grande do Sul - Brasil (1999-2002): diretrizes, dinâmica política e resultados atingidos

This paper has as objective to analyze the foundry work politics made by the Olívio Dutra's government in the state of Rio Grande do Sul-Brazil, being taken into account their guidelines, the dynamics of the political struggle promoted between the social leaders from the rural area and the achieved global results. This government's freshness is related to the fact of it was being sustained and supported by a coalition of left wing parties and by a group of social movements and also by syndical entities of the field, which was decisive in the presentation of an antagonistic program to the neoliberal politics on energy in a national extent. Hence this government became committed in adopting an own foundry work politics, being opposed to the program of market land reform extolled by Cardoso's government, in national wide. Therefore, the results presented along the article demonstrate that in spite of the assumed commitments and, in face of legal, institutional and economical limitations and also its existent politics, the space of the state governments' performance can only be thought about its complemental character on the federal government's actions.

A política fundiária do governo Olívio Dutra no Rio Grande do Sul - Brasil (1999-2002): diretrizes, dinâmica política e resultados atingidos

This paper has as objective to analyze the foundry work politics made by the Olívio Dutra's government in the state of Rio Grande do Sul-Brazil, being taken into account their guidelines, the dynamics of the political struggle promoted between the social leaders from the rural area and the achieved global results. This government's freshness is related to the fact of it was being sustained and supported by a coalition of left wing parties and by a group of social movements and also by syndical entities of the field, which was decisive in the presentation of an antagonistic program to the neoliberal politics on energy in a national extent. Hence this government became committed in adopting an own foundry work politics, being opposed to the program of market land reform extolled by Cardoso's government, in national wide. Therefore, the results presented along the article demonstrate that in spite of the assumed commitments and, in face of legal, institutional and economical limitations and also its existent politics, the space of the state governments' performance can only be thought about its complemental character on the federal government's actions.

Receptores homodinos a 300 GHz basados en tecnología CMOS

Using CMOS transistors for terahertz detection is currently a disruptive technology that offers the direct integration of a terahertz detector with video preamplifiers. The detectors are based on the resistive mixer concept and its performance mainly depends on the following parameters: type of antenna, electrical parameters (gate to drain capacitor and channel length of the CMOS device) and foundry. Two different 300 GHz detectors are discussed: a single transistor detector with a broadband antenna and a differential pair driven by a resonant patch antenna.

300 GHz CMOS video detection using broadband and active planar antennas

Using CMOS transistors for terahertz detection is currently a disruptive technology that offers the direct integration of a terahertz detector with video preamplifiers. The detectors are based on the resistive mixer concept and performance mainly depends on the following parameters: type of antenna, electrical parameters (gate to drain capacitor and channel length of the CMOS device) and foundry. Two different 300 GHz detectors are discussed: a single transistor detector with a broadband antenna and a differential pair driven by a resonant patch antenna.

The practical American cook book, or, Practical and scientific cookery /

Publisher's advertisements on p. [1]-[12] (2nd group).

Experimental safety car study. Phase I. Final report.

National Highway Safety Bureau, Washington, D.C.

Mathematical simulation models for crashworthiness qualification of motor vehicle structures. Phase I. Final report.

National Highway Safety Bureau, Washington, D.C.

Vehicle bumper performance study.

National Highway Safety Bureau, Washington, D.C.

Door locking systems study. Phase 1. Final report.

National Highway Safety Bureau, Washington, D.C.

Performance requirements for doors, door retaining devices and adjacent structures.

National Highway Safety Bureau, Washington, D.C.

Open shop review.

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