Soluzioni per il controllo delle testine di lettura/scrittura in hard disk drive magnetici

Questa tesi descrive alcune tecniche realizzative e algoritmi di controllo per il posizionamento delle testine di lettura/scrittura in hard disk drive magnetici. Viene presentata l'attuazione a due stadi delle testine per incrementare la banda frequenziale del sistema, in cui un motore VCM funge da primo stadio e come secondo stadio si utilizza un microattuatore, di tipo piezoelettrico o elettromagnetico o elettrotermico. Il posizionamento della testina sulle tracce magnetiche dei dischi contenenti i dati si divide in due fasi: track-seeking e track-following, che presentano diversi requisiti di velocità e precisione, per questo motivo si descrive il metodo dello switching control. Successivamente viene formulato un modello matematico nello spazio degli stati degli stati dell'attuatori a due stadi e il relativo controllo in retroazione, basato su osservatore dello stato. Inoltre per il track-seeking si propone il controllo a due gradi di libertà e per il track-following il metodo del disaccoppiamento della sensitività. Infine si riportano due novità tecnologiche per gli hard disk magnetici: l'attuazione a tre stadi, che sfrutta un secondo microattuatore, di tipo termico, e gli hard disk riempiti d'elio ed ermeticamente sigillati, che semplificano il controllo grazie alla minore turbolenza del gas e al suo minor peso.

“It’s the People That Drive It”: Motivating and Supporting Collaborative Data Use Practices in Three Teacher Education Programs

Thesis (Ph.D.)--University of Washington, 2016-08

Searching for Masculine Capital: Experiences Leading to High Drive for Muscularity in Men

Studies on the drive for muscularity (DFM) have primarily been quantitative, focused on identifying correlates. Currently little is known about men’s experiences leading them to desire high levels of muscle and engage in behaviours to increase their masculine capital. Our purpose was to explore the stories of men with high DFM revealing the socio-cultural and personal factors leading to DFM and their search for masculine capital. In-depth life-history interviews and multiple in-the-field conversations were undertaken with twenty men (Mean age=28.45, SD=6.96, years) scoring ≥ 3 on the Drive for Muscularity Scale (Mean=4.30, SD=0.70). Men’s stories focused on a set of dysfunctional childhood and adolescent socio-cultural interactions, including forms of symbolic violence, between them and significant others. In these interactions men were exposed to dominant social narratives of masculinity, and through comparisons and reinforcement they identified discrepancies between themselves and these narratives. In late adolescence and early adulthood men came to believe that they lacked masculine capital. Men struggled to increase their masculine capital through engagement with other traditional masculine activities (e.g., sport) and driven by activating events, they compensated through DFM desires and behaviours. This study advances knowledge by revealing the socio-cultural and personal processes participants believed led to their high DFM. Findings disclose that men’s search for masculine capital may have led them to develop and maintain high levels of DFM.

Factors that drive Female Entrepreneurship in Armenia

Entrepreneurs play a key role in any economy. Entrepreneurship includes creativity, innovation, risk taking, planning and management and is described as transferring ideas into action. Female entrepreneurship, in particular, is considered an important tool in enabling female empowerment and emancipation. In the light of recent world events, this has become a crucial area to study and understand, especially with respect to motivations, obstacles, constraints and consequences of female entrepreneurship. Having the previous framework in attention, this thesis focuses on female entrepreneurship in a developing country - Armenia – and proposes a conceptual framework of the phenomenon. A joint cooperation between the World Bank and the European Bank for Reconstruction and Development allowed to conduct an enterprise survey in the country and from that survey a microeconomic dataset was released and applied in this research study. A logistic regression econometric method is applied to the dataset to identify and measure the relationship between female entrepreneurship and several factors such as the location, size, legal status, market and obstacles faced by Armenian firms. The study concludes that women entrepreneurs in Armenia share many common features and obstacles with their male counterparts. Moreover, gender of the top managers, the firm’s location, size, main market type, the number of competitors and full-time employees, the adoption of new marketing methods, the access to land, the tax administration system and an inadequately educated workforce are found to be statistical significant factors in the explanation of female entrepreneurship in Armenia.

Effects of Drive Speed Modulation on Dynamics of Slender Rotating Structures

Slender rotating structures are used in many mechanical systems. These structures can suffer from undesired vibrations that can affect the components and safety of a system. Furthermore, since some these structures can operate in a harsh environment, installation and operation of sensors that are needed for closed-loop and collocated control schemes may not be feasible. Hence, the need for an open-loop non-collocated scheme for control of the dynamics of these structures. In this work, the effects of drive speed modulation on the dynamics of slender rotating structures are studied. Slender rotating structures are a type of mechanical rotating structures, whose length to diameter ratio is large. For these structures, the torsion mode natural frequencies can be low. In particular, for isotropic structures, the first few torsion mode frequencies can be of the same order as the first few bending mode frequencies. These situations can be conducive for energy transfer amongst bending and torsion modes. Scenarios with torsional vibrations experienced by rotating structures with continuous rotor-stator contact occur in many rotating mechanical systems. Drill strings used in the oil and gas industry are an example of rotating structures whose torsional vibrations can be deleterious to the components of the drilling system. As a novel approach to mitigate undesired vibrations, the effects of adding a sinusoidal excitation to the rotation speed of a drill string are studied. A portion of the drill string located within a borewell is considered and this rotating structure has been modeled as an extended Jeffcott rotor and a sinusoidal excitation has been added to the drive speed of the rotor. After constructing a three-degree-of-freedom model to capture lateral and torsional motions, the equations of motions are reduced to a single differential equation governing torsional vibrations during continuous stator contact. An approximate solution has been obtained by making use of the Method of Direct Partition of Motions with the governing torsional equation of motion. The results showed that for a rotor undergoing forward or backward whirling, the addition of sinusoidal excitation to the drive speed can cause an increase in the equivalent torsional stiffness, smooth the discontinuous friction force at contact, and reduce the regions of negative slope in the friction coefficient variation with respect to speed. Experiments with a scaled drill string apparatus have also been conducted and the experimental results show good agreement with the numerical results obtained from the developed models. These findings suggest that the extended Jeffcott rotordynamics model can be useful for studies of rotor dynamics in situations with continuous rotor-stator contact. Furthermore, the results obtained suggest that the drive speed modulation scheme can have value for attenuating drill-string vibrations.

Successional dynamics in inland dune shrub communities drive changes in functional diversity

Communities can be defined as assemblages of species coexisting under particular environments. The relationship between environment and species are regulated by both environmental requirements –which ultimately determine the species capacity to establish and survive in a particular environment– and the ecological interactions occurring during assembly processes –which also determine community composition by conditioning species coexistence. In this context, plant functional traits are attributes that represent ecological strategies and determine how plants respond to environmental factors and interact with other species. Therefore, the analysis of how traits vary through the dynamics of communities, such as along successions, can give insights about how environmental requirements and species interactions may determine the composition and functional structure of these communities. The xerophytic shrub communities inhabiting inland sand dunes in SW Portugal are characterized by successional processes that are mainly driven by local (edaphic gradients and human disturbance) and regional (climate) processes. Therefore, they constitute an appropriate system for studying species interactions and environmentcommunity co-variations based on functional terms. Using these communities as a model, we evaluate the hypothesis that successional community changes in species composition of xerophytic shrub communities can result in concurrent changes in functional diversity

Export and import market-specific characteristics. How they drive the decision to trade and how much

Using a rich firm-level dataset on the Italian manufacturing industry, this paper provides a comprehensive analysis of the role that firms and market characteristics play in shaping firms’ trade activities. We enhance the previous analyses by considering firms’ engagement in international transactions, by focusing on either exports or imports. We show that the determinants of a firm’s export participation and value across countries also drive import behavior. Our research is consistent with the presence of country-specific sunk costs and with a qualitatively similar role of gravity forces and other country attributes on both sides of trading activities. Our evidence, however, militates in favor of a framework where variations in market characteristics have a larger impact on imports than exports.

Design Optimization of Modern Machine-drive Systems for Maximum Fault Tolerant and Optimal Operation

Modern electric machine drives, particularly three phase permanent magnet machine drive systems represent an indispensable part of high power density products. Such products include; hybrid electric vehicles, large propulsion systems, and automation products. Reliability and cost of these products are directly related to the reliability and cost of these systems. The compatibility of the electric machine and its drive system for optimal cost and operation has been a large challenge in industrial applications. The main objective of this dissertation is to find a design and control scheme for the best compromise between the reliability and optimality of the electric machine-drive system. The effort presented here is motivated by the need to find new techniques to connect the design and control of electric machines and drive systems. A highly accurate and computationally efficient modeling process was developed to monitor the magnetic, thermal, and electrical aspects of the electric machine in its operational environments. The modeling process was also utilized in the design process in form finite element based optimization process. It was also used in hardware in the loop finite element based optimization process. The modeling process was later employed in the design of a very accurate and highly efficient physics-based customized observers that are required for the fault diagnosis as well the sensorless rotor position estimation. Two test setups with different ratings and topologies were numerically and experimentally tested to verify the effectiveness of the proposed techniques. The modeling process was also employed in the real-time demagnetization control of the machine. Various real-time scenarios were successfully verified. It was shown that this process gives the potential to optimally redefine the assumptions in sizing the permanent magnets of the machine and DC bus voltage of the drive for the worst operating conditions. The mathematical development and stability criteria of the physics-based modeling of the machine, design optimization, and the physics-based fault diagnosis and the physics-based sensorless technique are described in detail. To investigate the performance of the developed design test-bed, software and hardware setups were constructed first. Several topologies of the permanent magnet machine were optimized inside the optimization test-bed. To investigate the performance of the developed sensorless control, a test-bed including a 0.25 (kW) surface mounted permanent magnet synchronous machine example was created. The verification of the proposed technique in a range from medium to very low speed, effectively show the intelligent design capability of the proposed system. Additionally, to investigate the performance of the developed fault diagnosis system, a test-bed including a 0.8 (kW) surface mounted permanent magnet synchronous machine example with trapezoidal back electromotive force was created. The results verify the use of the proposed technique under dynamic eccentricity, DC bus voltage variations, and harmonic loading condition make the system an ideal case for propulsion systems.

Autarcie radicale et autarcie dérivée chez Proclus : le problème de l’autarcie de l’âme par illumination

Louis-André Dorion, dans un article publié en 2006 « Platon, Proclus et l’autarcie du monde », affirme que le concept d’autarcie dérivée de Proclus est un non-sens. Nous montrerons dans cet article que, loin d’être aporétique, le concept d’autarcie dérivée est tout à fait cohérent avec le système philosophique de Proclus. Pour défendre notre thèse, nous nous intéresserons spécifiquement à l’autarcie de l’âme, à travers le phénomène d’illumination suivant le processus de purification de l’âme séparable chez Proclus, rendant compte du caractère autoconstitutif de l’âme. Ainsi, nous comprendrons en quoi l’ontologie proclusienne permet de saisir les hypostases (Un, intellect et âme), non pas dans un rapport de causalité unilatérale hiérarchique, mais plutôt selon une dialectique de procession centrifuge et de conversion centripète. Finalement, il nous sera possible d’exposer que l’idée de dérivation ne contredit pas l’essence de l’autarcie, mais en est plutôt sa propre condition de possibilité.

Autarcie radicale et autarcie dérivée chez Proclus : le problème de l’autarcie de l’âme par illumination

Louis-André Dorion, dans un article publié en 2006 « Platon, Proclus et l’autarcie du monde », affirme que le concept d’autarcie dérivée de Proclus est un non-sens. Nous montrerons dans cet article que, loin d’être aporétique, le concept d’autarcie dérivée est tout à fait cohérent avec le système philosophique de Proclus. Pour défendre notre thèse, nous nous intéresserons spécifiquement à l’autarcie de l’âme, à travers le phénomène d’illumination suivant le processus de purification de l’âme séparable chez Proclus, rendant compte du caractère autoconstitutif de l’âme. Ainsi, nous comprendrons en quoi l’ontologie proclusienne permet de saisir les hypostases (Un, intellect et âme), non pas dans un rapport de causalité unilatérale hiérarchique, mais plutôt selon une dialectique de procession centrifuge et de conversion centripète. Finalement, il nous sera possible d’exposer que l’idée de dérivation ne contredit pas l’essence de l’autarcie, mais en est plutôt sa propre condition de possibilité.

Modeling, Component Selection and Optimization of Servo-controlled Automatic Machinery

A servo-controlled automatic machine can perform tasks that involve synchronized actuation of a significant number of servo-axes, namely one degree-of-freedom (DoF) electromechanical actuators. Each servo-axis comprises a servo-motor, a mechanical transmission and an end-effector, and is responsible for generating the desired motion profile and providing the power required to achieve the overall task. The design of a such a machine must involve a detailed study from a mechatronic viewpoint, due to its electric and mechanical nature. The first objective of this thesis is the development of an overarching electromechanical model for a servo-axis. Every loss source is taken into account, be it mechanical or electrical. The mechanical transmission is modeled by means of a sequence of lumped-parameter blocks. The electric model of the motor and the inverter takes into account winding losses, iron losses and controller switching losses. No experimental characterizations are needed to implement the electric model, since the parameters are inferred from the data available in commercial catalogs. With the global model at disposal, a second objective of this work is to perform the optimization analysis, in particular, the selection of the motor-reducer unit. The optimal transmission ratios that minimize several objective functions are found. An optimization process is carried out and repeated for each candidate motor. Then, we present a novel method where the discrete set of available motor is extended to a continuous domain, by fitting manufacturer data. The problem becomes a two-dimensional nonlinear optimization subject to nonlinear constraints, and the solution gives the optimal choice for the motor-reducer system. The presented electromechanical model, along with the implementation of optimization algorithms, forms a complete and powerful simulation tool for servo-controlled automatic machines. The tool allows for determining a wide range of electric and mechanical parameters and the behavior of the system in different operating conditions.

Effective procedure for the optimization of the linear controller in an industrial drive for a nonlinear mechanism

Il progetto di tesi è incentrato sull’ottimizzazione del procedimento di taratura dei regolatori lineari degli anelli di controllo di posizione e velocità presenti negli azionamenti usati industrialmente su macchine automatiche, specialmente quando il carico è ad inerzia variabile in dipendenza dalla posizione, dunque non lineare, come ad esempio un quadrilatero articolato. Il lavoro è stato svolto in collaborazione con l’azienda G.D S.p.A. ed il meccanismo di prova è realmente utilizzato nelle macchine automatiche per il packaging di sigarette. L’ottimizzazione si basa sulla simulazione in ambiente Matlab/Simulink dell’intero sistema di controllo, cioè comprensivo del modello Simulink degli anelli di controllo del drive, inclusa la dinamica elettrica del motore, e del modello Simscape del meccanismo, perciò una prima necessaria fase del lavoro è stata la validazione di tali modelli affinché fossero sufficientemente fedeli al comportamento reale. Il secondo passo è stato fornire una prima taratura di tentativo che fungesse da punto di partenza per l’algoritmo di ottimizzazione, abbiamo fatto ciò linearizzando il modello meccanico con l’inerzia minima e utilizzando il metodo delle formule di inversione per determinare i parametri di controllo. Già questa taratura, seppur conservativa, ha portato ad un miglioramento delle performance del sistema rispetto alla taratura empirica comunemente fatta in ambito industriale. Infine, abbiamo lanciato l’algoritmo di ottimizzazione definendo opportunamente la funzione di costo, ed il risultato è stato decisamente positivo, portando ad un miglioramento medio del massimo errore di inseguimento di circa il 25%, ma anche oltre il 30% in alcuni casi.

Drive up electrochemical and electrochemiluminescence signal through biosensing mechanism optimization

Biomarkers are biological indicators of human health conditions. Their ultra-sensitive quantification is of cardinal importance in clinical monitoring and early disease diagnosis. Biosensors are some worldwide simple and easy-to-use analytical devices as a matter of fact, biosensors using electrochemiluminescence (ECL) are one of the most promising biosensors that needs an ever-increasing sensitivity for improving its clinical effectiveness. The principal aspiration of this project is the investigation of the ECL generation mechanisms for enhancing the ECL intensity and the development of an ultrasensitive sensor, the use of metal-oxide materials (Mox) and the substitution of metal-free dyes. Novel dyes such as BODIPY, TADF are used to improve the sensitivity of ECL techniques thanks to their advantageous and tunable properties, enhancing the signal and also the ECL efficiency. Additionally, the use of Mox could be beneficial for the investigation of two different ECL mechanisms, which occur simultaneously. In this thesis, the investigation of size and distance effects on electrochemical (EC) mechanisms was carried out through the innovative combination of a standard detection system using different size of micromagnetic beads (MBs). That allowed the discovery of an unexpected and highly efficient mechanistic path for electrochemical generation at small distances from the electrode’s surface. The smallest MBs (0.1μm) demostrate an enhancement of electrochemical signal than the bigger one (2.8μm) until 4 times of magnitude. Finally, a novel ultrasensitive sensor, based on the coreactant-luminophores mechanism, was developed for the determination of whole viral genome specific for cardiac HBV and COVID-19 virus. In conclusion, the ECL and the use of EC techniques (such as amperometry), improved the understanding of mechanisms responsible for the ECL/EC signal led to a great enhancement in the signal.