Impact of the motor magnetic model on direct flux vector control of interior PM motors

The stator-field-oriented, direct-flux vector control has been proven to be effective in terms of linear torque control and model independent performance at limited voltage and current (i.e. in flux weakening) for AC drives of various types. The performance of the direct-flux vector control relies on the accuracy of the flux estimation, as for any field oriented control. The knowledge of the motor magnetic model is critical for flux estimation when the operating at low speed. This paper addresses the effects of a limited knowledge of the motor model on the performance of the control at low speed, for an Interior Permanent Magnet motor drive. Experimental results are give

Multistage quantum absorption heat pumps

This is the final version. Available from American Physical Society via the DOI in this recordIt is well known that heat pumps, while being all limited by the same basic thermodynamic laws, may find realization on systems as “small” and “quantum” as a three-level maser. In order to quantitatively assess how the performance of these devices scales with their size, we design generalized N-dimensional ideal heat pumps by merging N−2 elementary three-level stages. We set them to operate in the absorption chiller mode between given hot and cold baths and study their maximum achievable cooling power and the corresponding efficiency as a function of N . While the efficiency at maximum power is roughly size-independent, the power itself slightly increases with the dimension, quickly saturating to a constant. Thus, interestingly, scaling up autonomous quantum heat pumps does not render a significant enhancement beyond the optimal double-stage configuration

Quantum-enhanced absorption refrigerators

Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators

Paikallisen aktiivisen melunhallintajärjestelmän kehittäminen

Active noise control (ANC) is a technology reducing noise by incorporating secondary sources, producing so called anti-noise. This anti-noise has the same amplitude but inverted phase at all frequencies compared to the primary noise under subject of attenuation, resulting in the two sound fields canceling each other out by the principle of superposition. The aim of this thesis is to evaluate the feasibility of using a mobile simple single-channel ANC system to reduce broadband noise in a 3D-space. To achieve this, different known ANC algorithms are simulated, and based on the simulations, a physical prototype device is developed and tested. Based on literature review, the only viable solution to the problem is to develop a local feedback ANC system. Local ANC systems minimize sound pressure at a single point in space instead of the entire room, and feedback ANC systems conduct the attenuation without prior knowledge of the incoming noise. Thus, feedback ANC is a prediction problem at its core. Three algorithms are simulated: leaky filtered-x least mean squares algorithm (LFxLMS), functional link artificial neural network based LFxLMS (FLANN), and wavelet packet transform based LFxLMS (Wavelet). Out of these three, LFxLMS and Wavelet were then tested with the prototype system. Both algorithms achieved over 6 dB reduction on low-frequency fan noise, around 1--3 dB reduction on orchestral music, around 1 dB reduction on traffic noise, but virtually no reduction on speech, depending on measurement location. The results show that such a feedback local ANC system is able to attenuate noise with strong tonal components but cannot attenuate sound that varies quickly in time. Additionally, it was confirmed that secondary path latency forms the biggest limitation of a feedback ANC system and must be minimized for the system to work well.Aktiivinen melunhallinta (active noise control, ANC) on tekniikka, jolla voidaan vähentää melua tuottamalla toisiokaiuttimella niin kutsuttua vastamelua. Tällä vastamelulla on sama amplitudi mutta käänteinen vaihe vaimennettavaan primäärimeluun nähden, jolloin nämä kaksi äänikenttää kumoavat toisensa superpositioperiaatteen mukaisesti. Tämän diplomityön tavoitteena on arvioida yksinkertaisen yksikanavaisen aktiiviseen melunhallintaan perustuvan laitteen käyttökelpoisuutta laajakaistaisen melun vaimentamiseksi 3D-tilassa. Tavoitteen saavuttamiseksi työssä simuloidaan tunnettuja aktiivisen melunhallinnan algoritmeja, ja simulointien pohjalta kehitetään prototyyppilaite. Kirjallisuuskatsauksen perusteella ainoa käytettävissä oleva ratkaisu ongelmaan on kehittää paikallinen takaisinkytketty ANC-järjestelmä. Paikalliset ANC-järjestelmät minimoivat äänenpainetta yhdessä pisteessä koko huoneen sijaan, ja takaisinkytketyt ANC-järjestelmät tuottavat vastamelua ilman ennakkotietoa tulevasta primäärimelusta. Takaisinkytketty ANC on siten pohjimmiltaan ennustamisongelma. Työssä simuloidaan kolmea algoritmia: vuotava referenssisuodatettu pienimmän neliösumman algoritmi (leaky filtered-x least mean squares, LFxLMS), funktionaaliseen linkkineuroverkkoon perustuva LFxLMS (functional link neural network, FLANN) ja lyhyen aaltomuodon muunnokseen perustuva LFxLMS (wavelet packet transform, Wavelet). Näistä kolmesta LFxLMS ja Wavelet testattiin myös prototyyppijärjestelmällä. Molemmat algoritmit saavuttivat yli 6 dB vaimennuksen matalataajuuksiseen tuuletinmeluun, noin 1--3 dB vaimennuksen orkesterimusiikkiin, ja noin 1 dB vaimennuksen liikennemeluun, mittauspaikasta riippuen. Puheeseen kumpikaan algoritmi ei juuri saavuttanut vaimennusta. Tulokset osoittavat, että tämänkaltainen takaisinkytketty, paikallinen ANC-järjestelmä pystyy vaimentamaan melua, jolla on vahvat, tasaiset tonaaliset komponentit, mutta ei kykene vaimentamaan nopeasti ajassa muuttuvaa ääntä. Lisäksi tulokset vahvistavat, että toisiotien viive on suurin yksittäinen rajoittava tekijä takaisinkytketyissä ANC-järjestelmissä

Collider phenomenology of new physics Beyond the Standard Model

On the one hand, the Standard Model has been established as the best description of the fundamental laws of nature. On the other hand, various phenomena remain unaddressed, motivating the study of Beyond the Standard Model theories along with future experimental concepts that can pinpoint the right direction forward. Looking into new physics from multiple perspectives, this thesis presents different phenomenological studies utilising both model-dependent and -independent approaches. A comparison of future experiments is presented within a simplified dark matter model, allowing the assessment of the constraints on the parameter space. In theories with extended scalar sectors, the capacity of cascade scalar decays in the potential discovery of new physics is showcased, taking advantage of the discriminative power of Neural Networks. The applicability of such Machine Learning techniques also extends to effective field theories leading to critically improved bounds on Wilson Coefficients attainable in the top sector. Finally, particular measurements from experiments related to CP violation in the gauge-Higgs sector and the muon’s anomalous magnetic moment are scrutinised within the Standard Model Effective Field Theory framework

Parallel performance wizard: A performance analysis tool for partitioned global-address-space programming models

Scientific programmers must optimize the total time-to-solution, the combination of software development and refinement time and actual execution time. The increasing complexity at all levels of supercomputing architectures, coupled with advancements in sequential performance and a growing degree of hardware parallelism, has increasingly placed the bulk of the time-to-solution cost into the software development and tuning phase. Performance analysis tools have been useful for reducing the time-to-solution for message-passing applications; however, there is insufficient tool support for programs developed using Global-Address-Space (GAS) programming models. With the aim of maximizing user productivity, the Parallel Performance Wizard (PPW) fills this void by providing a full range of visualizations and analyses specifically designed for GAS models. To facilitate accurate instrumentation and measurement of GAS programs in PPW, a portable, model-independent performance tool interface (GASP) has been developed and successfully used with Berkeley UPC. © 2006 IEEE

Parallel performance wizard: A performance analysis tool for partitioned global-address-space programming models

Scientific programmers must optimize the total time-to-solution, the combination of software development and refinement time and actual execution time. The increasing complexity at all levels of supercomputing architectures, coupled with advancements in sequential performance and a growing degree of hardware parallelism, has increasingly placed the bulk of the time-to-solution cost into the software development and tuning phase. Performance analysis tools have been useful for reducing the time-to-solution for message-passing applications; however, there is insufficient tool support for programs developed using Global-Address-Space (GAS) programming models. With the aim of maximizing user productivity, the Parallel Performance Wizard (PPW) fills this void by providing a full range of visualizations and analyses specifically designed for GAS models. To facilitate accurate instrumentation and measurement of GAS programs in PPW, a portable, model-independent performance tool interface (GASP) has been developed and successfully used with Berkeley UPC. © 2006 IEEE