Physical dynamic simulation of shipboard power system components in a distributed computational environment

Shipboard power systems have different characteristics than the utility power systems. In the Shipboard power system it is crucial that the systems and equipment work at their peak performance levels. One of the most demanding aspects for simulations of the Shipboard Power Systems is to connect the device under test to a real-time simulated dynamic equivalent and in an environment with actual hardware in the Loop (HIL). The real time simulations can be achieved by using multi-distributed modeling concept, in which the global system model is distributed over several processors through a communication link. The advantage of this approach is that it permits the gradual change from pure simulation to actual application. In order to perform system studies in such an environment physical phase variable models of different components of the shipboard power system were developed using operational parameters obtained from finite element (FE) analysis. These models were developed for two types of studies low and high frequency studies. Low frequency studies are used to examine the shipboard power systems behavior under load switching, and faults. High-frequency studies were used to predict abnormal conditions due to overvoltage, and components harmonic behavior. Different experiments were conducted to validate the developed models. The Simulation and experiment results show excellent agreement. The shipboard power systems components behavior under internal faults was investigated using FE analysis. This developed technique is very curial in the Shipboard power systems faults detection due to the lack of comprehensive fault test databases. A wavelet based methodology for feature extraction of the shipboard power systems current signals was developed for harmonic and fault diagnosis studies. This modeling methodology can be utilized to evaluate and predicate the NPS components future behavior in the design stage which will reduce the development cycles, cut overall cost, prevent failures, and test each subsystem exhaustively before integrating it into the system.

Physical dynamic simulation of shipboard power system components in a distributed computational environment

Shipboard power systems have different characteristics than the utility power systems. In the Shipboard power system it is crucial that the systems and equipment work at their peak performance levels. One of the most demanding aspects for simulations of the Shipboard Power Systems is to connect the device under test to a real-time simulated dynamic equivalent and in an environment with actual hardware in the Loop (HIL). The real time simulations can be achieved by using multi-distributed modeling concept, in which the global system model is distributed over several processors through a communication link. The advantage of this approach is that it permits the gradual change from pure simulation to actual application. In order to perform system studies in such an environment physical phase variable models of different components of the shipboard power system were developed using operational parameters obtained from finite element (FE) analysis. These models were developed for two types of studies low and high frequency studies. Low frequency studies are used to examine the shipboard power systems behavior under load switching, and faults. High-frequency studies were used to predict abnormal conditions due to overvoltage, and components harmonic behavior. Different experiments were conducted to validate the developed models. The Simulation and experiment results show excellent agreement. The shipboard power systems components behavior under internal faults was investigated using FE analysis. This developed technique is very curial in the Shipboard power systems faults detection due to the lack of comprehensive fault test databases. A wavelet based methodology for feature extraction of the shipboard power systems current signals was developed for harmonic and fault diagnosis studies. This modeling methodology can be utilized to evaluate and predicate the NPS components future behavior in the design stage which will reduce the development cycles, cut overall cost, prevent failures, and test each subsystem exhaustively before integrating it into the system.

Abordagens de estudo e performance da obra Responsório ao vento para violoncelo solo de Sílvio Ferraz

Recognized for his relevant writing for the cello, Silvio Ferraz wrote , in 2012, Segundo Responsório for cello solo and chamber group which followed Responsório ao Vento , a version of the same piece for solo cello . The work is characterized by the idea of continuity of sound moving through different textures , timbres , dynamics and musical gestures. The composer uses extended techniques, such as large sections in sul tasto playing three strings simultaneously, trills of natural harmonics , muffled trills with natural harmonics , col legno batuto , different types of glissando and simultaneous sounds of harmonic and non harmonic notes corroborate to a wealth of sounds and layers that create different textures. This article investigates the relationship of the composer with the cello, and relates Responsório ao Vento to his other works and studies the influences of the composer addressing technical and interpretive aspects of the piece drawn from performance experiences.

Music therapy, in tuning at the end of life

In this article music therapy is presented as a helpful tool to support the persons (and their relatives) living at the end of their life and, also, as a non pharmacological and complementary therapy in an integral and holistic medicine. What we report here comes from the direct experience, nourished after many years of interventions and reflections in oncology and palliative care units. We’re talking about silence, music, therapy, models and techniques. We will read and feel therapeutic sessions… but above all, we’re talking about life, conscience and love.

Digital predistortion for compensation of nonlinearities in Radio over Fiber Links

In order to cope up with the ever increasing demand for larger transmission bandwidth, Radio over Fiber technology is a very beneficial solution. These systems are expected to play a major role within future fifth generation wireless networks due to their inherent capillary distribution properties. Nonlinear compensation techniques are becoming increasingly important to improve the performance of telecommunication channels by compensating for channel nonlinearities. Indeed, significant bounds on the technology usability and performance degradation occur due to nonlinear characteristics of optical transmitter, nonlinear generation of spurious frequencies, which, in the case of RoF links exploiting Directly Modulated Lasers , has the combined effect of laser chirp and optical fiber dispersion among its prevailing causes. The purpose of the research is to analyze some of the main causes of harmonic and intermodulation distortion present in Radio over Fiber (RoF) links, and to suggest a solution to reduce their effects, through a digital predistortion technique. Predistortion is an effective and interesting solution to linearize and this allows to demonstrate that the laser’s chirp and the optical fiber’s dispersion are the main causes which generate harmonic distortion. The improvements illustrated are only theoretical, based on a feasibility point of view. The simulations performed lead to significant improvements for short and long distances of radio over fiber link lengths. The algorithm utilized for simulation has been implemented on MATLAB. The effects of chirp and fiber nonlinearity in a directly modulated fiber transmission system are investigated by simulation, and a cost effective and rather simple technique for compensating these effects is discussed. A detailed description of its functional model is given, and its attractive features both in terms of quality improvement of the received signal, and cost effectiveness of the system are illustrated.

Photochemical dynamics of laser-irradiated semiconductor nanostructures

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

Uma contribuição para a medição de distorções harmônicas e inter-harmônicas em instalações de geração fotovoltaica

Dissertação (mestrado)— Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2015.

The twentieth century jazz piano trio: the rise of an iconic jazz paradigm

Considerando a gravação de 1947 The Bud Powell Trio como a gravação referência de trio de piano de jazz moderno, esta tese centra-se no surgimento e evolução do trio de jazz moderno cujo líder é pianista. Começando por apresentar, uma resenha dos estilos e técnicas para piano de da época pre-Powell, esta tese investiga a génese dos trios de piano jazz e examina três dos mais influeciais pianostas de jazz e lideres dos mais legendários trios de piano jazz modernos: Bud Powell, Bill Evans e Keith Jarrett. Esta tese também abordará o paradoxo inerente a um sistema democrático - a expressão própria do individuo, em justaposição com a responsabilidade para com o todo – e a sua inequivoca analogia com o gestalt do trio de piano de jazz moderno. Desde a primeira gravação de um trio de jazz com pianista como líder em 1935, o trio de jazz moderno, evoluiu tornando-se um exemplo de democracia – um contexto de igualdade em que as funções rítmicas, harmónicas, e melódicas estão igualmente distribuídas entre os três instrumentistas, que são ao mesmo tempo solistas e acompanhadores. Esta tese sublinha a eficácia do trio de jazz moderno – o seu início, e porque subsiste – baseado na sua força e beleza estética; ABSTRACT: THE TWENTIETH CENTURY JAZZ PIANO TRIO – The Rise of an Iconic Jazz Paradigm by Susan Muscarella Designating Bud Powell’s 1947 recording, The Bud Powell Trio, as the modern jazz piano trio benchmark, here, this thesis traces the emergence and evolution of the pianistled, piano-bass-drums-comprised modern jazz piano trio. Beginning with a general overview of pre-Powell jazz piano styles and techniques, this thesis investigates the earliest, most salient pre-Powell jazz piano trios, and examines three seminal modern jazz pianists and leaders of legendary modern jazz piano trios, Bud Powell, Bill Evans and Keith Jarrett. This thesis also brings to the fore the paradox inherent in a democratic system – individual self-expression juxtaposed with responsibility to the whole – and its unequivocal analogy to the modern jazz piano trio gestalt. From the earliest recording of a primarily piano-dominated piano-bass-drums-comprised jazz piano trio in 1935, the modern jazz piano trio has evolved to become a paragon of democracy – an egalitarian playing field in which rhythmic, harmonic and melodic roles are evenly distributed among all three instrumentalists who have come to serve as both soloists and accompanists.

An in-depth analysis of original compositions

The purpose of this thesis is two-fold. It presents six original pieces composed and arranged by the author, and it provides a thorough analysis of each. The compositions draw from many different musical genres: contemporary jazz, swing, funk, fusion, soul, neo-soul, and rhythm and blues. The applications of melodic, harmonic, and rhythmic techniques derived from these genres can be found in these original compositions. These compositions are inspired by -- and attempt to narrate --life experiences. Parallels between life and music are drawn and explained. By way of introduction, some information is given regarding the ensemble that first performed these original compositions. The ensemble comprised trumpet, tenor saxophone, keyboards, piano, electric bass, upright acoustic bass, drums, and percussion.

Frequency adjustable MEMS vibration energy harvester

Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging "Internet-of-Things". However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

Dynamics of undeactuated cable-driven parallel robots

This thesis focuses on the dynamics of underactuated cable-driven parallel robots (UACDPRs), including various aspects of robotic theory and practice, such as workspace computation, parameter identification, and trajectory planning. After a brief introduction to CDPRs, UACDPR kinematic and dynamic models are analyzed, under the relevant assumption of inextensible cables. The free oscillatory motion of the end-effector (EE), which is a unique feature of underactuated mechanisms, is studied in detail, from both a kinematic and a dynamic perspective. The free (small) oscillations of the EE around equilibria are proved to be harmonic and the corresponding natural oscillation frequencies are analytically computed. UACDPR workspace computation and analysis are then performed. A new performance index is proposed for the analysis of the influence of actuator errors on cable tensions around equilibrium configurations, and a new type of workspace, called tension-error-insensitive, is defined as the set of poses that a UACDPR EE can statically attain even in presence of actuation errors, while preserving tensions between assigned (positive) bounds. EE free oscillations are then employed to conceive a novel procedure aimed at identifying the EE inertial parameters. This approach does not require the use of force or torque measurements. Moreover, a self-calibration procedure for the experimental determination of UACDPR initial cable lengths is developed, which consequently enables the robot to automatically infer the EE initial pose at machine start-up. Lastly, trajectory planning of UACDPRs is investigated. Two alternative methods are proposed, which aim at (i) reducing EE oscillations even when model parameters are uncertain or (ii) eliminate EE oscillations in case model parameters are perfectly known. EE oscillations are reduced in real-time by dynamically scaling a nominal trajectory and filtering it with an input shaper, whereas they can be eliminated if an off-line trajectory is computed that accounts for the system internal dynamics.

Harmonic oscillators driven by colored noise: crossovers, resonances and spectra

We study second-order properties of linear oscillators driven by exponentially correlated noise. We focus our attention on dynamical exponents and crossovers and also on resonance phenomena that appear when the driving noise is dichotomous. We also obtain the power spectrum and show its different behaviors according to the color of the noise.

Analytical potentials for triatomic molecules IX. The prediction of anharmonic force constants from potential energy surfaces based on harmonic force fields and dissociation energies for SO2 and O3

Analytical potential energy functions which are valid at all dissociation limits have been derived for the ground states of SO2 and O3. The procedure involves minimizing the errors between the observed vibrational spectra and spectra calculated by a variational procedure. Good agreement is obtained between the observed and calculated spectra for both molecules. Comparisons are made between anharmonic force fields, previously determined from the spectral data, and the force fields obtained by differentiating the derived analytical functions at the equilibrium configurations.

Temperature effects on a network of dissipative quantum harmonic oscillators: collective damping and dispersion processes

In this paper we extend the results presented in (de Ponte, Mizrahi and Moussa 2007 Phys. Rev. A 76 032101) to treat quantitatively the effects of reservoirs at finite temperature in a bosonic dissipative network: a chain of coupled harmonic oscillators whatever its topology, i.e., whichever the way the oscillators are coupled together, the strength of their couplings and their natural frequencies. Starting with the case where distinct reservoirs are considered, each one coupled to a corresponding oscillator, we also analyze the case where a common reservoir is assigned to the whole network. Master equations are derived for both situations and both regimes of weak and strong coupling strengths between the network oscillators. Solutions of these master equations are presented through the normal ordered characteristic function. These solutions are shown to be significantly involved when temperature effects are considered, making difficult the analysis of collective decoherence and dispersion in dissipative bosonic networks. To circumvent these difficulties, we turn to the Wigner distribution function which enables us to present a technique to estimate the decoherence time of network states. Our technique proceeds by computing separately the effects of dispersion and the attenuation of the interference terms of the Wigner function. A detailed analysis of the dispersion mechanism is also presented through the evolution of the Wigner function. The interesting collective dispersion effects are discussed and applied to the analysis of decoherence of a class of network states. Finally, the entropy and the entanglement of a pure bipartite system are discussed.

Advance P. Chem. Problems (I) Populations, Partition Functions, Particle in Box, Harmonic Oscillators, Angular Momentum and Rigid Rotor

This is a set of P. Chem. problems posed at slightly higher than the normal text book level, for students who are continuing in the study of this subject.