986 resultados para quasi-stationary


Relevância:

20.00% 20.00%

Publicador:

Resumo:

La tesis presenta evidencia rigurosa de la efectividad de las políticas públicas utilizando metodologías experimentales y cuasi-experimentales. La tesis comienza con una introducción completa y una revisión rigurosa de las metodologías que se utilizarán en el análisis posterior de los datos. El primer capítulo, "Habilidades personales y habilidades técnicas en programas de formación de jóvenes. Evidencia Experimental de Largo Plazo de República Dominicana ", evalúa el impacto de un programa de empleo de los jóvenes en una serie de variables de interés. El programa ofrece capacitación en las habilidades vocacionales y en las habilidades no cognitivas a jóvenes en riesgo de exclusión social. Cabe destacar que la metodología utilizada para evaluar el programa es un ensayo controlado aleatorio, que proporciona evidencia robusta del efecto causal del programa. Mientras que estudios previos analizaron el impacto de los programas para jóvenes relacionados, ningún estudio anterior había evaluado los efectos de 4 años después de la implementación del programa. Esto representa una contribución importante debido a que las ganancias a corto plazo de varios programas de desarrollo han demostrado no ser sostenida en el tiempo. Esto es también lo que este estudio encuentra para los resultados del mercado de trabajo: mientras que el programa genera una mejora a corto plazo de los resultados de empleo para las mujeres, este efecto se disipa en el largo plazo. Sin embargo, el programa parece conducir a cambios persistentes en las expectativas del mercado de trabajo de las mujeres: las mujeres que asistieron al entrenamiento de informar una visión más optimista de las perspectivas del mercado de trabajo hasta 4 años después del programa...

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Proline (Pro) is a unique amino acid that has been examined previously as a potential chiral selector for high-performance liquid chromatography. In recent years, a new class of promising Pro based enantioselective stationary phases has been studied and the longer peptides were found to be competitive with commercial chiral stationary phases (CSPs). Here, we aim to perform a comprehensive examination of a t-butoxycarbonyl- (t-Boc-) terminated monoproline selector. This selector was grafted through an amide linkage to an aminopropyl siloxane-terminated Si (111) wafer and to a silicon atomic force microscopy tip. To ensure a flat, homogeneous overlayer of selectors suitable for force spectrometric measurements, the prepared surfaces were characterized using XPS, AFM and contact angle measurements. Chemical force spectrometry (CFS) has been used to examine the chiral discrimination in our monoproline CSP by measuring the interaction forces between two D- or L-monoproline monolayers in water and in the presence of a series of amino acids in solution to explore the degree to which binding of amino acids impacts self-selectivity. Chemical force titration (CFT) has been used to observe the influence of variations in pH on the binding interaction of proline modified chiral surfaces. Here we aim to explore the connection between side-chain hydrophobicity and differences in the nature of the binding between different ionic forms of amino acids and the t-Boc-Pro interface, and thereby to gain insight into the mechanism of chiral selectivity. The CFS results show several trends for different proline selector/amino acid combinations and indicate that the binding characteristics of amino acid to the proline surface is strongly dependent on the amino acid side chain where hydrophilic side chain amino acids exhibit a selectivity opposite to that seen for those with hydrophobic side chains. The CFT studies also provide valuable insights into interactions between the proline selector and the amino acids under a wide range of pH conditions, indicating that protonated amine groups of alanine and serine are closely involved in the binding mechanism to proline surfaces. On the other hand, the presence of the second carboxylic group in aspartic acid plays an important role while interacting with proline.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A number of laws in Canada which uphold rights are referred to as quasi-constitutional by the courts in recognition of their special importance. Quasi-constitutional statutes are enacted through the regular legislative process, although they are being interpreted and applied in a fashion which has become remarkably similar to constitutional law, and are therefore having an important affect over other legislation. Quasi-constitutionality has surprisingly received limited scholarly attention, and very few serious attempts at explaining its significance have been made. This dissertation undertakes a comprehensive study of quasi-constitutionality which considers its theoretical basis, its interpretation and legal significance, as well as its similarities to comparable forms of law in other Commonwealth jurisdictions. Part I examines the theoretical basis of quasi-constitutionality and its relationship to the Constitution. As a statutory and common law form of fundamental law, quasi-constitutionality is shown to signify an association with the Canadian Constitution and the foundational principles that underpin it. Part II proceeds to consider the special rules of interpretation applied to quasi-constitutional legislation, the basis of this interpretative approach, and the connection between the interpretation of similar provisions in quasi-constitutional legislation and the Constitution. As a statutory form of fundamental law, quasi-constitutional legislation is given a broad, liberal and purposive interpretation which significantly expands the rights which they protect. The theoretical basis of this approach is found in both the fundamental nature of the rights upheld by quasi-constitutional legislation as well as legislative intent. Part III explores how quasi-constitutional statutes affect the interpretation of regular legislation and how they are used for the purposes of judicial review. Quasi-constitutional legislation has a significant influence over regular statutes in the interpretative exercise, which in some instances results in conflicting statutes being declared inoperable. The basis of this form of judicial review is demonstrated to be rooted in statutory interpretation, and as such it provides an interesting model of rights protection and judicial review that is not conflated to constitutional and judicial supremacy.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Recent developments have made researchers to reconsider Lagrangian measurement techniques as an alternative to their Eulerian counterpart when investigating non-stationary flows. This thesis advances the state-of-the-art of Lagrangian measurement techniques by pursuing three different objectives: (i) developing new Lagrangian measurement techniques for difficult-to-measure, in situ flow environments; (ii) developing new post-processing strategies designed for unstructured Lagrangian data, as well as providing guidelines towards their use; and (iii) presenting the advantages that the Lagrangian framework has over their Eulerian counterpart in various non-stationary flow problems. Towards the first objective, a large-scale particle tracking velocimetry apparatus is designed for atmospheric surface layer measurements. Towards the second objective, two techniques, one for identifying Lagrangian Coherent Structures (LCS) and the other for characterizing entrainment directly from unstructured Lagrangian data, are developed. Finally, towards the third objective, the advantages of Lagrangian-based measurements are showcased in two unsteady flow problems: the atmospheric surface layer, and entrainment in a non-stationary turbulent flow. Through developing new experimental and post-processing strategies for Lagrangian data, and through showcasing the advantages of Lagrangian data in various non-stationary flows, the thesis works to help investigators to more easily adopt Lagrangian-based measurement techniques.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Exploration of sustainable fuels and their influence on reductions in diesel emissions are nowadays a challenge for the engine and fuel researchers. This study investigates the role of fuel-borne oxygen on engine performance and exhaust emissions with a special emphasis on diesel particulate and nitric oxide (NO) emissions. A number of oxygenated-blends were prepared with waste cooking biodiesel as a base oxygenated fuel. Triacetin, a derivative from transesterified biodiesel was chosen for its high oxygen content and superior fuel properties. The experimental campaign was conducted with a 6-cylinder, common rail turbocharged diesel engine equipped with highly precise instruments for nano and other size particles and other emissions. All experiments were performed in accordance with European Stationary Cycle (ESC 13-mode). A commercial diesel was chosen as a reference fuel with 0% oxygen and five other oxygenated blends having a range of 6.02–14.2% oxygen were prepared. The experimental results revealed that the oxygenated blends having higher a percentage of fuel-borne oxygen reduced particulate matter (PM), particle number (PN), unburned hydrocarbon (UBHC) and carbon monoxide (CO) emissions to a significantly low level with a slight penalty of NO emissions. The main target of this study was to effectively utilise triacetin as an additive for waste cooking biodiesel and suppress emissions without deteriorating engine performance. The key finding of this investigation is the significant reductions in both particle mass and number emissions simultaneously without worsening engine performance with triacetin-biodiesel blends. Reductions in both particle mass and number emissions with a cost-effective additive would be a new dimension for the fuel and engine researchers to effectively use triacetin as an emission suppressor in the future.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Anomaly detection in a WSN is an important aspect of data analysis in order to identify data items that significantly differ from normal data. A characteristic of the data generated by a WSN is that the data distribution may alter over the lifetime of the network due to the changing nature of the phenomenon being observed. Anomaly detection techniques must be able to adapt to a non-stationary data distribution in order to perform optimally. In this survey, we provide a comprehensive overview of approaches to anomaly detection in a WSN and their operation in a non-stationary environment.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this paper we propose new panel tests to detect changes in persistence. The test statistics are used to test the null hypothesis of stationarity against the alternative of a change in persistence from I(0) to I(1), from I(1) to I(0), and in an unknown direction. The limiting null distributions of the tests are derived and evaluated in small samples by means of Monte Carlo simulations. An empirical illustration is also provided.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Min/max autocorrelation factor analysis (MAFA) and dynamic factor analysis (DFA) are complementary techniques for analysing short (> 15-25 y), non-stationary, multivariate data sets. We illustrate the two techniques using catch rate (cpue) time-series (1982-2001) for 17 species caught during trawl surveys off Mauritania, with the NAO index, an upwelling index, sea surface temperature, and an index of fishing effort as explanatory variables. Both techniques gave coherent results, the most important common trend being a decrease in cpue during the latter half of the time-series, and the next important being an increase during the first half. A DFA model with SST and UPW as explanatory variables and two common trends gave good fits to most of the cpue time-series. (c) 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We use a probing strategy to estimate the time dependent traffic intensity in an Mt/Gt/1 queue, where the arrival rate and the general service-time distribution change from one time interval to another, and derive statistical properties of the proposed estimator. We present a method to detect a switch from a stationary interval to another using a sequence of probes to improve the estimation. At the end, we compare our results with two estimators proposed in the literature for the M/G/1 queue.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Numerical techniques such as the Boundary Element Method, Finite Element Method and Finite Difference Time Domain have been used widely to investigate plane and curved wave-front scattering by rough surfaces. For certain shapes of roughness elements (cylinders, semi-cylinders and ellipsoids) there are semi-analytical alternatives. Here, we present a theory for multiple scattering by cylinders on a hard surface to investigate effects due to different roughness shape, the effects of vacancies and variation of roughness element size on the excess attenuation due to a periodically rough surfaces.