Acoustic radiation and scattering from cylindrical bodies and analysis of transducer arrays

New mathematical methods to analytically investigate linear acoustic radiation and scattering from cylindrical bodies and transducer arrays are presented. Three problems of interest involving cylinders in an infinite fluid are studied. In all the three problems, the Helmholtz equation is used to model propagation through the fluid and the beam patterns of arrays of transducers are studied. In the first problem, a method is presented to determine the omni-directional and directional far-field pressures radiated by a cylindrical transducer array in an infinite rigid cylindrical baffle. The solution to the Helmholtz equation and the displacement continuity condition at the interface between the array and the surrounding water are used to determine the pressure. The displacement of the surface of each transducer is in the direction of the normal to the array and is assumed to be uniform. Expressions are derived for the pressure radiated by a sector of the array vibrating in-phase, the entire array vibrating in-phase, and a sector of the array phase-shaded to simulate radiation from a rectangular piston. It is shown that the uniform displacement required for generating a source level of 220 dB ref. μPa @ 1m that is omni directional in the azimuthal plane is in the order of 1 micron for typical arrays. Numerical results are presented to show that there is only a small difference between the on-axis pressures radiated by phased cylindrical arrays and planar arrays. The problem is of interest because cylindrical arrays of projectors are often used to search for underwater objects. In the second problem, the errors, when using data-independent, classical, energy and split beam correlation methods, in finding the direction of arrival (DOA) of a plane acoustic wave, caused by the presence of a solid circular elastic cylindrical stiffener near a linear array of hydrophones, are investigated. Scattering from the effectively infinite cylinder is modeled using the exact axisymmetric equations of motion and the total pressures at the hydrophone locations are computed. The effect of the radius of the cylinder, a, the distance between the cylinder and the array, b, the number of hydrophones in the array, 2H, and the angle of incidence of the wave, α, on the error in finding the DOA are illustrated using numerical results. For an array that is about 30 times the wavelength and for small angles of incidence (α<10), the error in finding the DOA using the energy method is less than that using the split beam correlation method with beam steered to α; and in some cases, the error increases when b increases; and the errors in finding the DOA using the energy method and the split beam correlation method with beam steered to α vary approximately as a7 / 4 . The problem is of interest because elastic stiffeners – in nearly acoustically transparent sonar domes that are used to protect arrays of transducers – scatter waves that are incident on it and cause an error in the estimated direction of arrival of the wave. In the third problem, a high-frequency ray-acoustics method is presented and used to determine the interior pressure field when a plane wave is normally incident on a fluid cylinder embedded in another infinite fluid. The pressure field is determined by using geometrical and physical acoustics. The interior pressure is expressed as the sum of the pressures due to all rays that pass through a point. Numerical results are presented for ka = 20 to 100 where k is the acoustic wavenumber of the exterior fluid and a is the radius of the cylinder. The results are in good agreement with those obtained using field theory. The directional responses, to the plane wave, of sectors of a circular array of uniformly distributed hydrophones in the embedded cylinder are then computed. The sectors are used to simulate linear arrays with uniformly distributed normals by using delays. The directional responses are compared with the output from an array in an infinite homogenous fluid. These outputs are of interest as they are used to determine the direction of arrival of the plane wave. Numerical results are presented for a circular array with 32 hydrophones and 12 hydrophones in each sector. The problem is of interest because arrays of hydrophones are housed inside sonar domes and acoustic plane waves from distant sources are scattered by the dome filled with fresh water and cause deterioration in the performance of the array.

Design and synthesis of efficient mac architectures for high speed decimal processor

Most of the commercial and financial data are stored in decimal fonn. Recently, support for decimal arithmetic has received increased attention due to the growing importance in financial analysis, banking, tax calculation, currency conversion, insurance, telephone billing and accounting. Performing decimal arithmetic with systems that do not support decimal computations may give a result with representation error, conversion error, and/or rounding error. In this world of precision, such errors are no more tolerable. The errors can be eliminated and better accuracy can be achieved if decimal computations are done using Decimal Floating Point (DFP) units. But the floating-point arithmetic units in today's general-purpose microprocessors are based on the binary number system, and the decimal computations are done using binary arithmetic. Only few common decimal numbers can be exactly represented in Binary Floating Point (BF P). ln many; cases, the law requires that results generated from financial calculations performed on a computer should exactly match with manual calculations. Currently many applications involving fractional decimal data perform decimal computations either in software or with a combination of software and hardware. The performance can be dramatically improved by complete hardware DFP units and this leads to the design of processors that include DF P hardware.VLSI implementations using same modular building blocks can decrease system design and manufacturing cost. A multiplexer realization is a natural choice from the viewpoint of cost and speed.This thesis focuses on the design and synthesis of efficient decimal MAC (Multiply ACeumulate) architecture for high speed decimal processors based on IEEE Standard for Floating-point Arithmetic (IEEE 754-2008). The research goal is to design and synthesize deeimal'MAC architectures to achieve higher performance.Efficient design methods and architectures are developed for a high performance DFP MAC unit as part of this research.

Short-Term Load Forecast Of A Low Loadfactor Power System For Optimization Of Merit Order Dispatch Using Adaptive Learning Algorithm

Short term load forecasting is one of the key inputs to optimize the management of power system. Almost 60-65% of revenue expenditure of a distribution company is against power purchase. Cost of power depends on source of power. Hence any optimization strategy involves optimization in scheduling power from various sources. As the scheduling involves many technical and commercial considerations and constraints, the efficiency in scheduling depends on the accuracy of load forecast. Load forecasting is a topic much visited in research world and a number of papers using different techniques are already presented. The accuracy of forecast for the purpose of merit order dispatch decisions depends on the extent of the permissible variation in generation limits. For a system with low load factor, the peak and the off peak trough are prominent and the forecast should be able to identify these points to more accuracy rather than minimizing the error in the energy content. In this paper an attempt is made to apply Artificial Neural Network (ANN) with supervised learning based approach to make short term load forecasting for a power system with comparatively low load factor. Such power systems are usual in tropical areas with concentrated rainy season for a considerable period of the year

Certified Rapid Solution of Parametrized Linear Elliptic Equations: Application to Parameter Estimation

We present a technique for the rapid and reliable evaluation of linear-functional output of elliptic partial differential equations with affine parameter dependence. The essential components are (i) rapidly uniformly convergent reduced-basis approximations — Galerkin projection onto a space WN spanned by solutions of the governing partial differential equation at N (optimally) selected points in parameter space; (ii) a posteriori error estimation — relaxations of the residual equation that provide inexpensive yet sharp and rigorous bounds for the error in the outputs; and (iii) offline/online computational procedures — stratagems that exploit affine parameter dependence to de-couple the generation and projection stages of the approximation process. The operation count for the online stage — in which, given a new parameter value, we calculate the output and associated error bound — depends only on N (typically small) and the parametric complexity of the problem. The method is thus ideally suited to the many-query and real-time contexts. In this paper, based on the technique we develop a robust inverse computational method for very fast solution of inverse problems characterized by parametrized partial differential equations. The essential ideas are in three-fold: first, we apply the technique to the forward problem for the rapid certified evaluation of PDE input-output relations and associated rigorous error bounds; second, we incorporate the reduced-basis approximation and error bounds into the inverse problem formulation; and third, rather than regularize the goodness-of-fit objective, we may instead identify all (or almost all, in the probabilistic sense) system configurations consistent with the available experimental data — well-posedness is reflected in a bounded "possibility region" that furthermore shrinks as the experimental error is decreased.

Correlación entre el resultado refractivo post-catarata con la predicción biométrica pre-operatoria

La cirugía de cataratas por Facoemulsificación es tal vez uno de los procedimientos más realizados en la práctica de oftalmología general, sin embargo el resultado refractivo de esta cirugía no siempre llena las expectativas del oftalmólogo y del paciente, es por esto que es de gran importancia observar los resultados post quirúrgicos obtenidos y las distintas variables que pudieron influir en dicho resultado. Objetivo: determinar la capacidad predictiva de la formula biométrica empleada en el preoperatorio con el resultado refractivo post operatorio expresada en porcentajes. Materiales y métodos: se realizó un estudio de correlación basándose en la refracción prevista por la biometría y la refracción encontrada en el post operatorio. Se analizó los diferentes grupos de pacientes miopes, hipermétropes y emétropes en de los rangos de 0,50D, 0,75 D y 1,00D. Resultados: el porcentaje de pacientes que presento 0,50D de diferencia con el previsto fue de 57,7% para el total, 100% para hipermétropes, 53,1% para emétropes, 56,3% para miopes. En el rango de 0,75D 71,2% para el total, 62,5% para emétropes y 81,3% para miopes. En el rango de 1,00D 82,7% para el total, 75% para emétropes y 93,8% para miopes. Conclusiones: la formula SRK/T presento un buen desempeño en todos los grupos encontrándose resultados concordantes con los descritos en la literatura.

La responsabilidad patrimonial del Estado por la falla en la prestación del servicio médico asistencial. Acto médico defectuoso en las entidades de salud del Estado. -Una visión desde la doctrina y desarrollo jurisprudencial del Consejo de Estado-.

La complejidad que supone abarcar el estudio de la responsabilidad patrimonial del Estado en el ámbito médico sanitario, hace preciso prestar atención a ciertos temas que resultan especialmente relevantes y que han sido decantados jurisprudencialmente por el Honorable Consejo de Estado. De esta manera el presente trabajo desarrolla temas descollantes y novedosos en materia de imputabilidad como viene a ser la prueba de la falla médica mediante la teoría "res ipsa loquitur"; la prueba del nexo causal a través de la prueba indiciaria y la teoría de la probabilidad preponderante. Así mismo se estudian los diversos tipos de daños antijurídicos que pueden darse dentro de la prestación médica a cargo del Estado, destacando especialmente la lesión al derecho a recibir una atención oportuna y eficaz, la pérdida de una oportunidad debida a la no obtención del consentimiento informado del paciente, lo que supone, a su vez, el cercenamiento del derecho de este a elegir someterse o no a determinado tratamiento, previo valoración de pros y contras de la terapia sugerida por el galeno (principio de no agravación). Así mismo se analizanlas hipótesis de daños antijurídicos derivados del error en el diagnóstico, la falla por la omisión de las entidades de control y vigilancia, falla en gineco-obstetricia, así como las hipótesis de responsabilidad objetiva del Estado por óblito quirúrgico, para finalmente tratar el tema novedoso del alea terapéutica con sus particulares características y eventual aplicabilidad en el sistema jurídico colombiano.

Noviolencia y desobediencia civil

This paper analyzes and describes the relationship between nonviolence and civil disobedience, stressing that both of them converge on the same ethical foundation and are an expression of the relationship between citizens and the political power.  The paper begins with a presentation of nonviolence Mahatma Gandhi´s work, and continues then conceptualizing nonviolence as a political thought, with a  epistemology and an action. Finally, traces a connection between nonviolence and civil disobedience that goes beyond the purely instrumental relationship that usually  identifies the link between these. Thus, beyond their differences both nonviolence  and civil desobedience, concur in essence, that is, in the ethical principles that support and legitimize them as actions and political expressions.

En busca de una nueva sociedad. Los aportes de la teoría feminista a la reformulación del mundo moderno

Este artículo analiza las aportaciones de las teorías feministas a la reformulación de los paradigmas de la teoría política actual. Se retoman dos ejes temáticos: el problema del reconocimiento de la diferencia y la redefinición de la dicotomía público-privado, ambos introducidos en el debate político moderno por el feminismo. En el caso de la diferencia, se analiza específicamente el problema de la representación y su legitimidad. La dicotomía privado-público se aborda desde el enfoque de la ética del cuidado y sus paralelismos con los principios de la economía social. La conclusión afirma que el feminismo es, en esencia, una reflexión sobre la condición del ser humano, concreto en su sexualidad, pero universal en su derecho al reconocimiento.-----This article analyzes the contributions of the feminist theories to the reformulation of the current political theory paradigms. Two topical axes are reexamined: the issue of the recognition of differences and the redefinition of the public-private dichotomy, both introduced into the modern political discussion by the feminism. In the case of the difference, representation and its legitimacy issue are analyzed in particular. The private-public dichotomy is approached from the ethics of care viewpoint and its parallelisms with the principles of social economy. It concludes that feminism is, in essence, a meditation on the human being condition, concrete on his or her sexuality, but universal on his or her right to recognition.

Conflict, wages, and multiple equilibria

Firms’ compensation practices affect the protection of investors’ interests and the degree of economic inequality by changing the stakes of engaging in appropriation activities versus respecting the status quo. We use a general equilibrium model where workers can either work peacefully or join a guerrilla movement that expropriates entrepreneurs. If workers are peaceful, they receive a competitive wage. If they join a guerrilla movement, they receive a share of the appropriated wealth, which depends positively on the number of guerrilla members. In this framework, we find one low-income, low-wage equilibrium with guerrilla activity and one peaceful, high-income, high-wage equilibrium. The peaceful equilibrium can be reached through redistribution policies, which can be implemented at the firm level. In essence, through their compensation policies entrepreneurs, not the state might be able to protect their assets against expropriation and simultaneously control the internal principal-agent problem.

Tres experiencias para pensar la educación en derechos humanos en Colombia

A lo largo de esta investigación se analizaron comparativamente tres experiencias auto-definidas como de Educación en Derechos Humanos, a saber, una organización no gubernamental, la Escuela de Derechos Humanos de Cinep; un colegio oficial de la ciudad de Bogotá, la IED Eduardo Umaña Mendoza; y un movimiento social, el Movimiento Nacional de Víctimas de Crímenes de Estado-Capítulo Bogotá. En lo fundamental, se analizaron los procesos de constitución de cada escenario, los discursos, y las prácticas políticas y pedagógicas a la luz de un enfoque antropológico de la Educación en Derechos Humanos. Lo que he denominado el enfoque o mirada antropológica de esta noción, implica, por una parte, una aproximación etnográfica alrededor de los discursos, las prácticas y los sentidos que los protagonistas movilizan en cada escenario con respecto a lo educativo, a los Derechos Humanos y a los sentidos de la Educación en Derechos Humanos, y por otra, la distinción entre la diversidad de redes de significado que precedieron su proceso de institucionalización, a lo cual denominaré campo simbólico, y su cohesión como un campo de saber dotado de claves analíticas propias. Campo simbólico y campo de saber operan como dos momentos analíticos diferenciables. A través del primero, se hacen evidentes las representaciones políticas, sociales y culturales heredadas del “mundo bipolar” y de la guerra fría que en términos generales exponen una defensa a ultranza de los valores y principios de la democracia liberal y de la lucha anti-comunista. Por otra parte, la noción de campo de saber permite 6 esbozar las trayectorias que le han permitido a la Educación en Derechos Humanos recrear nociones como la de sujeto de derechos o pedagogías de la memoria, claves que sin lugar a dudas cohesionan un cuerpo de saber ciertamente autónomo, dotado de fronteras porosas y móviles. La distinción entre una y otra esfera de análisis permite trazar cuando menos tres rutas de emergencia e institucionalización de la Educación en Derechos Humanos que, como se expondrá en el análisis de las experiencias, no trascurren paralelamente sino en medio de superposiciones, intersticios y desplazamientos. Así, se hacen plausibles las huellas del colonialismo, permanentemente ligadas a voces disonantes que eventualmente arrojan pistas en torno a una Educación en Derechos Humanos capaz de impugnar su propia institucionalización.

Afganistán: rezago de la Guerra Fría (Coyuntura)

El autor explica la evolución de los acontecimientos en ese país desde 1973 y considera que el régimen de los Talibán y el apoyo y hospitalidad que le han dado a la organización Al Qaeda de Osama Bin Laden constituyen, en esencia, un rezago, o epílogo, de la Guerra Fría. El autor también explica los esfuerzos en curso para establecer en Afganistán un gobierno que garantice estabilidad y paz a un pueblo que ya ha sufrido demasiado durante casi tres décadas y examina algunas de las posibles motivaciones de los actos terroristas contra los Estados Unidos.

El recurso de casación en materia penal

El tema central y alcance de la presente tesis de maestría está circunscrito al actual recurso de casación penal, contenido en los artículos 656 y 657 del Código Orgánico Integral Penal. La perspectiva teórico-metodológica utilizada ha sido de tipo documental y dogmática, recurriendo primariamente a textos legales, doctrina y jurisprudencia actualizada. El concepto principal que sigue esta tesis es que actualmente se ha disuelto la pretensión original del fin político de la casación, pues no se puede seguir pensando en términos de una teórica justicia absoluta abstracta, sino más bien en ir hacia una justicia razonable del caso concreto. Por tanto la idea que debe guiarnos es que la protección del sistema jurídico se ha ampliado a la efectiva protección de los derechos y garantías fundamentales, lo cual termina contorneando la casación penal de una manera muy diferente a la originalmente diseñada para su funcionamiento. En el capítulo primero se realiza un análisis histórico de la casación, con su "fin político o Ius constitutionis", esto es las funciones nomofiláctica y la uniformadora, y la creciente importancia del "fin procesal o Ius litigatoris" esto es la función dikelógica. Se analiza las características y principios de la casación penal. Y la llegada y desenvolvimiento de dicha institución procesal penal en nuestro país. En el capítulo segundo, se realiza un análisis de la correcta conceptualización de los conceptos de error in procedendo y error in iudicando, y dentro de éste último el error de derecho (in jure) y el error de hecho (in facto). Se resalta el tema del error de juicio in iudicando in factum, esto es la problemática del segundo inciso del Art. 656 del COIP, que bien puede ser la parte más importante de esta tesis. En el capítulo tercero se analiza la técnica de casación penal; y se hace un análisis de los titulares del recurso, de su admisión, de la audiencia pública de fundamentación; así como de la sentencia de casación.

The predictability of extratropical storm tracks and the sensitivity of their prediction to the observing system

A new method for assessing forecast skill and predictability that involves the identification and tracking of extratropical cyclones has been developed and implemented to obtain detailed information about the prediction of cyclones that cannot be obtained from more conventional analysis methodologies. The cyclones were identified and tracked along the forecast trajectories, and statistics were generated to determine the rate at which the position and intensity of the forecasted storms diverge from the analyzed tracks as a function of forecast lead time. The results show a higher level of skill in predicting the position of extratropical cyclones than the intensity. They also show that there is potential to improve the skill in predicting the position by 1 - 1.5 days and the intensity by 2 - 3 days, via improvements to the forecast model. Further analysis shows that forecasted storms move at a slower speed than analyzed storms on average and that there is a larger error in the predicted amplitudes of intense storms than the weaker storms. The results also show that some storms can be predicted up to 3 days before they are identified as an 850-hPa vorticity center in the analyses. In general, the results show a higher level of skill in the Northern Hemisphere (NH) than the Southern Hemisphere (SH); however, the rapid growth of NH winter storms is not very well predicted. The impact that observations of different types have on the prediction of the extratropical cyclones has also been explored, using forecasts integrated from analyses that were constructed from reduced observing systems. A terrestrial, satellite, and surface-based system were investigated and the results showed that the predictive skill of the terrestrial system was superior to the satellite system in the NH. Further analysis showed that the satellite system was not very good at predicting the growth of the storms. In the SH the terrestrial system has significantly less skill than the satellite system, highlighting the dominance of satellite observations in this hemisphere. The surface system has very poor predictive skill in both hemispheres.

Evaluation of suitable spectral intervals for near-IR laboratory detection of water vapour continuum absorption

The water vapour continuum absorption is an important component of molecular absorption of radiation in atmosphere. However, uncertainty in knowledge of the value of the continuum absorption at present can achieve 100% in different spectral regions leading to an error in flux calculation up to 3-5 W/m2 global mean. This work uses line-by-line calculations to reveal the best spectral intervals for experimental verification of the CKD water vapour continuum models in the currently least studied near-infrared spectral region. Possible sources of errors in continuum retrieval taken into account in the simulation include the sensitivity of laboratory spectrometers and uncertainties in the spectral line parameters in HITRAN-2004 and Schwenke-Partridge database. It is shown that a number of micro-windows in near-IR can be used at present for laboratory detection of the water vapour continuum with estimated accuracy from 30 to 5%.

Achieving accurate FTIR measurements on high performance bandpass filters

The sources of ordinate error in FTIR spectrometers are reviewed with reference to measuring small out-of-band features in the spectra of bandpass filters. Procedures for identifying instrumental artefacts are described. It is shown that features well below 0.01%T can be measured reliably.