934 resultados para work zone traffic control
Resumo:
[ES]En el presente trabajo se tratará de exponer el método de trabajo, el desarrollo y los posibles usos de este dispositivo como un método de control en un marco de uso industrial orientado a la economía
Resumo:
Part I
The electric birefringence of dilute DNA solutions has been studied in considerable detail and on a large number of samples, but no new and reliable information was discovered concerning the tertiary structure of DNA. The large number of variables which effect the birefringence results is discussed and suggestions are made for further work on the subject.
The DNA molecules have been aligned in a rapidly alternating (10 to 20 kc/sec) square wave field confirming that the orientation mechanism is that of counterion polarization. A simple empirical relation between the steady state birefringence, Δnst, and the square of the electric field, E, has been found: Δnst = E2/(a E2 + b), where a = 1/Δns and b = (E2/Δnst)E→o. Δns is the birefringence extrapolated to infinite field strength.
The molecules show a distribution of relaxation times from 10-4 to 0.2 sec, which is consistent with expectations for flexible coil molecules. The birefringence and the relaxation times decrease with increasing salt concentrations. They also depend on the field strength and pulse duration in a rather non-reproducible manner, which may be due in part to changes in the composition of the solution or in the molecular structure of the DNA (other than denaturation). Further progress depends on the development of some control over these effects.
Part II
The specificity of the dissociation of reconstituted and native deoxyribonucleohistones (DNH) by monovalent salt solutions has been investigated. A novel zone ultracentrifugation method is used in which the DNH is sedimented as a zone through a preformed salt gradient, superimposed on a stabilizing D2O (sucrose) density gradient. The results, obtained by scanning the quartz sedimentation tubes in a spectrophotometer, were verified by the conventional, preparative sedimentation technique. Procedures are discussed for the detection of microgram quantities of histones, since low concentrations must be used to prevent excessive aggregation of the DNH.
The data show that major histone fractions are selectively dissociated from DNH by increasing salt concentrations: Lysine rich histone (H I) dissociates gradually between 0.1 and 0.3 F, slightly lysine rich histone (H II) dissociates as a narrow band between 0.35 and 0.5 F, and arginine rich histone (H III, H IV) dissociates gradually above 0.5 F NaClO4.
The activity of the partially dissociated, native DNH in sustaining RNA synthesis, their mobility and their unusual heat denaturation and renaturation behavior are described. The two-step melting behavior of the material indicates that the histones are non-randomly distributed along the DNA, but the implications are that the uncovered regions are not of gene-size length.
Resumo:
Climate change is arguably the most critical issue facing our generation and the next. As we move towards a sustainable future, the grid is rapidly evolving with the integration of more and more renewable energy resources and the emergence of electric vehicles. In particular, large scale adoption of residential and commercial solar photovoltaics (PV) plants is completely changing the traditional slowly-varying unidirectional power flow nature of distribution systems. High share of intermittent renewables pose several technical challenges, including voltage and frequency control. But along with these challenges, renewable generators also bring with them millions of new DC-AC inverter controllers each year. These fast power electronic devices can provide an unprecedented opportunity to increase energy efficiency and improve power quality, if combined with well-designed inverter control algorithms. The main goal of this dissertation is to develop scalable power flow optimization and control methods that achieve system-wide efficiency, reliability, and robustness for power distribution networks of future with high penetration of distributed inverter-based renewable generators.
Proposed solutions to power flow control problems in the literature range from fully centralized to fully local ones. In this thesis, we will focus on the two ends of this spectrum. In the first half of this thesis (chapters 2 and 3), we seek optimal solutions to voltage control problems provided a centralized architecture with complete information. These solutions are particularly important for better understanding the overall system behavior and can serve as a benchmark to compare the performance of other control methods against. To this end, we first propose a branch flow model (BFM) for the analysis and optimization of radial and meshed networks. This model leads to a new approach to solve optimal power flow (OPF) problems using a two step relaxation procedure, which has proven to be both reliable and computationally efficient in dealing with the non-convexity of power flow equations in radial and weakly-meshed distribution networks. We will then apply the results to fast time- scale inverter var control problem and evaluate the performance on real-world circuits in Southern California Edison’s service territory.
The second half (chapters 4 and 5), however, is dedicated to study local control approaches, as they are the only options available for immediate implementation on today’s distribution networks that lack sufficient monitoring and communication infrastructure. In particular, we will follow a reverse and forward engineering approach to study the recently proposed piecewise linear volt/var control curves. It is the aim of this dissertation to tackle some key problems in these two areas and contribute by providing rigorous theoretical basis for future work.
Resumo:
The cyanobacteria that cause problems in water supply are principally the colonial forms that are buoyed up by gas vesicles. The success of these organisms is due, in part, to their gas vesicles, which enable them to perform vertical migrations or to maintain themselves in the euphotic zone. The gas vesicles are also the root cause of the problems. In calm periods they cause the cyanobacteria to float to the water surface forming noxious scums, and they may prevent the colonies from sedimenting in water treatment plants. Gas vesicles are hollow, gas-filled structures; they are rigid but can be collapsed by the application of pressure. Their critical collapse pressure is influenced by their dimensions, which vary in different organisms. Gas vesicles are formed by the assembly of two types of protein, which determine their mechanical and physical properties. Methods for collapsing gas vesicles in natural populations of cyanobacteria will be considered. They may have application to the control of cyanobacteria in water supply.
Resumo:
In this paper, a real time sliding mode control scheme for a variable speed wind turbine that incorporates a doubly feed induction generator is described. In this design, the so-called vector control theory is applied, in order to simplify the system electrical equations. The proposed control scheme involves a low computational cost and therefore can be implemented in real-time applications using a low cost Digital Signal Processor (DSP). The stability analysis of the proposed sliding mode controller under disturbances and parameter uncertainties is provided using the Lyapunov stability theory. A new experimental platform has been designed and constructed in order to analyze the real-time performance of the proposed controller in a real system. Finally, the experimental validation carried out in the experimental platform shows; on the one hand that the proposed controller provides high-performance dynamic characteristics, and on the other hand that this scheme is robust with respect to the uncertainties that usually appear in the real systems.
Resumo:
Parametric fluctuations or stochastic signals are introduced into the rectangular pulse sequence to investigate the feasibility of random dynamical decoupling. In a large parameter region, we find that the out-of-order control pulses work as well as the regular pulses for dynamical decoupling and dissipation suppression. Calculations and analysis are enabled by and based on a nonperturbative dynamical decoupling approach allowed by an exact quantum-state-diffusion equation. When the average frequency and duration of the pulse sequence take proper values, the random control sequence is robust, fault-tolerant, and insensitive to pulse strength deviations and interpulse temporal separation in the quasi-periodic sequence. This relaxes the operational requirements placed on quantum control devices to a great deal.
Resumo:
This paper deals with the convergence of a remote iterative learning control system subject to data dropouts. The system is composed by a set of discrete-time multiple input-multiple output linear models, each one with its corresponding actuator device and its sensor. Each actuator applies the input signals vector to its corresponding model at the sampling instants and the sensor measures the output signals vector. The iterative learning law is processed in a controller located far away of the models so the control signals vector has to be transmitted from the controller to the actuators through transmission channels. Such a law uses the measurements of each model to generate the input vector to be applied to its subsequent model so the measurements of the models have to be transmitted from the sensors to the controller. All transmissions are subject to failures which are described as a binary sequence taking value 1 or 0. A compensation dropout technique is used to replace the lost data in the transmission processes. The convergence to zero of the errors between the output signals vector and a reference one is achieved as the number of models tends to infinity.
Resumo:
[ES]En la problemática medioambiental generada por la contaminación atmosférica hay tres aspectos que marcan las directrices de actuación institucional: la presión social, la legislación vigente y la tecnología disponible. En cuanto a este último aspecto, la biofiltración es una tecnología eficaz, asequible y sostenible basada en la actividad biodegradadora de microorganismos específicos adheridos a la superficie de un material soporte que constituye el lecho del biofiltro. La elección de un material soporte adecuado es de especial importancia para asegurar el correcto funcionamiento de los biofiltros. Esta decisión está basada en las propiedades intrínsecas del material que deben ser analizadas previamente a su uso. En este proyecto se ha seleccionado cuales son estas propiedades básicas a partir de una revisión bibliográfica, destacando la capacidad de retención de humedad, superficie específica, porosidad, y estabilidad física y química del material. En este trabajo, también se han fijado los parámetros de control que deben ser medidos de forma rutinaria en un biofiltro para asegurar la eficacia del tratamiento de descontaminación. En base a la información bibliográfica recopilada, se ha concluido que los parámetros básicos son pH, temperatura, contenido de humedad del lecho y pérdidas de carga. A nivel experimental, se han medido las pérdidas de carga generadas en biofiltros empacados con tres materiales soportes que son de especial interés para una investigación posterior a desarrollar por el grupo Biofiltración de la Universidad del País Vasco (UPV/EHU). Durante el período de arranque inicial de los tres biofiltros, las pérdidas de carga medidas fueron muy bajas en los tres casos, aunque algo superiores cuando la alimentación era en sentido ascendente frente al flujo descendente. Sin embargo, cuando se midieron las pérdidas de carga bajo condiciones de encharcamiento del lecho, que es una de las situaciones más problemáticas en un biofiltro, todos los soportes presentaron un aumento puntual de la pérdida de carga aunque la tendencia en los días posteriores fue claramente descendente, recuperando valores de operación habituales. La comparativa del comportamiento frente a las pérdidas de carga permitió seleccionar el soporte más idóneo de los tres analizados, aunque los otros dos podrían ser alternativas viables en caso de sustitución.
Resumo:
Resumen Background: Nitric oxide can be measured at multiple flow rates to determine proximal (maximum airway nitric oxide flux; Jaw(NO)) and distal inflammation (alveolar nitric oxide concentration; CA(NO)). The main aim was to study the association among symptoms, lung function, proximal (maximum airway nitric oxide flux) and distal (alveolar nitric oxide concentration) airway inflammation in asthmatic children treated and not treated with inhaled glucocorticoids. Methods: A cross-sectional study with prospective data collection was carried out in a consecutive sample of girls and boys aged between 6 and 16 years with a medical diagnosis of asthma. Maximum airway nitric oxide flux and alveolar nitric oxide concentration were calculated according to the two-compartment model. In asthmatic patients, the asthma control questionnaire (CAN) was completed and forced spirometry was performed. In controls, differences between the sexes in alveolar nitric oxide concentration and maximum airway nitric oxide flux and their correlation with height were studied. The correlation among the fraction of exhaled NO at 50 ml/s (FENO50), CA(NO), Jaw(NO), forced expiratory volume in 1 second (FEV1) and the CAN questionnaire was measured and the degree of agreement regarding asthma control assessment was studied using Cohen's kappa. Results: We studied 162 children; 49 healthy (group 1), 23 asthmatic participants without treatment (group 2) and 80 asthmatic patients treated with inhaled corticosteroids (group 3). CA(NO) (ppb) was 2.2 (0.1-4.5), 3 (0.2-9.2) and 2.45 (0.1-24), respectively. Jaw(NO) (pl/s) was 516 (98.3-1470), 2356.67 (120-6110) and 1426 (156-11805), respectively. There was a strong association (r = 0.97) between FENO50 and Jaw(NO) and the degree of agreement was very good in group 2 and was good in group 3. There was no agreement or only slight agreement between the measures used to monitor asthma control (FEV1, CAN questionnaire, CA(NO) and Jaw(NO)). Conclusions: The results for CA(NO) and Jaw(NO) in controls were similar to those found in other reports. There was no agreement or only slight agreement among the three measure instruments analyzed to assess asthma control. In our sample, no additional information was provided by CA(NO) and Jaw(NO).
Resumo:
The aim of this research study has been to design a gain scheduling (GS) digital controller in order to control the voltage of an islanded microgrid in the presence of fast varying loads (FVLs), and to compare it to a robust controller. The inverter which feeds the microgrid is connected to it through an inductance-capacitor-inductance (LCL) filter. The oscillatory and nonlinear behaviour of the plant is analyzed in the whole operating zone. Afterwards, the design of the controllers which contain two loops in cascade are described. The first loop concerns the current control, while the second is linked to the voltage regulation. Two controllers, one defined as Robust and another one as GS controller, are designed for the two loops, emphasizing in their robustness and their ability to damp the oscillatory plant behaviour. To finish, some simulations are carried out to study and compare the two kinds of controllers in different operating points. The results show that both controllers damp the oscillatory behaviour of the plant in closed loop (CL), and that the GS controller ensures a better rejection of current disturbances from FVLs.
Resumo:
[ES]El objetivo de este proyecto es programar el control numérico para la mecanización del escudo del Real Madrid. Para conseguir esto, primero es necesario aprender cómo funcionan los programas que se van a usar. Después de esto se va a crear el archivo CAD, usando el programa Solid Edge. Luego, usando el programa SurfCam Velocity 4.0 se programará el control numérico necesario para la fabricación del escudo.
Resumo:
[ES]Para la elaboración del presente proyecto, primeramente se explicara los requerimientos técnicos y el origen del microprocesador a utilizar para poder situar y centrar el tema del trabajo. Una vez acotado y delimitado el tema objeto de estudio, se planteara una arquitectura de software sobre la posibilidad de generar unas “pseudolibrerias” de mayor nivel de programación que el ensamblador. Posteriormente, se verificara la posible viabilidad o no de tal planteamiento, exponiendo sus resultados y las consideraciones oportunas a las que nos ha llevado su estudio. Para ello se analizara en una primera instancia el microprocesador a utilizar, que será el PIC16F887, centrándonos en el debido al amplio manejo y conocimiento que poseemos sobre este microprocesador. El objeto de este escrito será presentar una oferta económica relativa al desarrollo e instalación de dichos microprocesadores para la mejora en el ámbito industrial. Finalmente, realizaremos un estudio sobre la implementación de este tipo de arquitectura software en diferentes microprocesadores de mayores prestaciones, estudiando si la infraestructura será eficiente, funcional y económica.
Resumo:
En español:El sector público gestiona una gran cantidad de recursos para satisfacer las demandas de la sociedad de bienes y servicios públicos, como sanidad, educación, prestaciones sociales, etc. Y, cada vez más, se reclama por parte de los ciudadanos una utilización eficaz, y eficiente de dichos recursos. Es por ello que el papel de las instituciones que realizan el control del gasto público adquiere una importancia relevante. Este trabajo tiene como objetivo analizar cómo se lleva a cabo el control del gasto público en España, analizando los diferentes niveles de control, así como las instituciones que lo realizan y las relaciones existentes entre ellas, pudiendo constatar la necesidad de coordinación entre ellas para que los recursos que se destinan a la función de control no sean utilizados ineficientemente.
Resumo:
O objetivo desta tese consistiu em saber se os sentidos compartilhados e os significados construídos sobre o choro das crianças nas creches públicas do município de Juiz de Fora, durante as sessões reflexivas com as coordenadoras/diretoras, produzem espaços de reflexão teórica sobre as práticas capazes de criar uma prática de reflexão. Pelo tipo de problema formulado optei por trabalhar a perspectiva metodológica a partir do paradigma crítico de pesquisa, concretizado na modalidade de pesquisa crítica de colaboração, com enfoque sócio-histórico-cultural. Isto se justifica porque busco compreender o lugar do choro das crianças nas práticas das coordenadoras/diretoras, procurando identificar se a consciência das ações institucionalizadas pode produzir mudanças nas práticas no interior das creches. O corpus discurso da tese constitui-se de 10 sessões reflexivas, cujos dados produzidos foram organizados e analisados a partir da perspectiva teórico-metodológica dos Núcleos de Significação de Aguiar e Ozella (2006). O campo teórico está circunscrito no diálogo entre Vigotski, Bakhtin e Wallon. Isso porque estes autores contribuíram, sobremaneira, para a discussão sobre sentido, significado; linguagem e consciência, zona de desenvolvimento proximal, além do estudo da emoção, em especial, sobre a manifestação do choro da criança no contexto da creche. A arquitetura dos Núcleos de Significação revelou a necessidade de aprofundar questões relacionadas aos diversos olhares para o choro da criança; estratégias para lidar com o choro a partir da visão das coordenadoras/diretoras; o controle/descontrole/não controle do choro; a inter-relação do choro, da creche e da família e, finalmente, a reflexão teórico-prática como possibilidade de reverberação no cotidiano da creche. As análises confirmaram três premissas básicas: a) que a emoção constitui-se como o primeiro recurso de interação com o outro, que antecede a própria representação simbólica e por isso é valioso o aprofundamento deste assunto em cursos de formação; b) quando tornamos a cena vivida mais clara, essa clareza pode trazer elementos para outras possíveis intervenções, para outros possíveis diálogos sobre o choro da criança. A perspectiva de transformação pode acontecer exatamente no diálogo entre o cotidiano, a história e espaços de reflexão; c) que o fundamental, nos contextos de formação, é não focalizar apenas o conteúdo a ser transmitido sem possibilidade de reflexão sobre o próprio contexto a que se destina porque é pelo possível distanciamento e necessário estranhamento das práticas rotineiras, esporadicamente ou quase nunca questionadas, que a reflexão e a crítica se estabelecem.