1,721,014 research outputs found
Alloy 600의 준안정 공식 및 재부동태 거동에 미치는 부식억제제 의 영향
No full text학위논문(석사) - 한국과학기술원 : 신소재공학과, 2004.8, [ xv, 116 p. ]Alloy 600 is prone to stress corrosion cracking (SCC) and intergranular attack (IGA) on secondary side of Steam Generator (SG) applications. It is reported that addition of small amount of inhibitors to secondary water of SG tubing reduced propagation rate of stress corrosion cracks hence increases lifespan of SG tubes. At high temperature, SCC of Alloy 600 occurs by repetitive processes of passive film breakdown-dissolution-repassivation. Repassivation is a film reforming process on the film broken surface. SCC of Alloy 600 is controlled by several variables. However, under certain loading conditions for an alloy/environment system, SCC is function of repassivation rate.
Metastable pitting is also a process of film break down, dissolution and repassivation of an alloy. Thus, repassivation rate of Alloy 600 is of critical importance. However, there are very few studies on the influence of inhibitors on metastable pitting and repassivation kinetics of Alloy 600. Moreover, in spite of a couple of studies, the mechanism of inhibitors to reduce crack growth has not yet been elucidated.
Objective of present study is to examine effect of inhibitors on repassivation kinetics and electrochemical noise of Alloy 600 in pH 10 borate buffer solutions and in 10 % NaOH solutions at 90 ℃ and at 200 ℃. To identify the optimum inhibitor among the candidate inhibitors for Alloy 600 and to understand why inhibitors such as , and ZnO retard crack propagation of Alloy 600.
Effect of inhibitors on metastable pitting properties and repassivation kinetics of Alloy 600 in 1 M , pH 10 and 10 % NaOH solution were examined by electrochemical noise analysis (ENA) and rapid scratching electrode technique (RSET), respectively. Scope of repassivation kinetics was extended, and repassivation rate was measured by step potential technique (SPT) in pH10, 10 % NaOH and 1 M ...한국과학기술원 : 신소재공학과
Social implications of the Islamisation of General Zia-ul-Haq for Pakistan
Full text linkThis study aims to understand the context, patterns, and social implications of Islamisation Zia-ul-Haq in Pakistan. After seizing power, Zia started a manic process of Islamisation. One segment of Pakistani society believes that it has positive impacts, while others believe that it has negative consequences for society. This study investigates this disconcerted debate, and its nature is descriptive and explanatory because it tries to examine the queries of what and why. It is based on the literature review of secondary sources and an analysis of primary data. The thematic analysis model is used for the analysis of data. It was found that the patterns of Zia’s policy regarding state-religion relations were opposite to the vision of the founder Muhammad Ali Jinnah. The global, strategic, and socio-political contexts of Islamisation were the impulse behind that process. The consequences of this process are of concern, as it brought about extremism, sectarianism, and terrorism and negatively affected the human rights regime, polity, and education system. It is suggested that the state should stop patronising extremists’ narratives, adopt peaceful, mystical interpretations, separate matters of religion from state politics, and promote progressive interpretations and arrangements for a better future for the country
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Optimización de los sistemas de riego: un estudio de caso de Punjab, Pakistán
Full text linkEl país árido y agrícola de Pakistán depende en gran medida del Sistema de Riego de la Cuenca Indo, la cual es alimentada principalmente por el río Indo y sus afluentes Jhelum, Chenab, Ravi y Sutlej. Con el recurso hídrico limitado, el sistema agrícola de la provincia de Punjab necesita mejorar su eficiencia y distribución equitativa. Este estudio tiene como objetivo desarrollar un modelo de red flexible que involucra una serie de nodos interconectados para caracterizar el sistema de riego de Punjab, Pakistán. El modelo se calibró utilizando el método Bayesiano de Monte Carlo, donde el conocimiento sobre los parámetros de pérdida/ganancia se actualizó con la información de datos observados.
Los resultados del modelo de red propuesto fueron aceptables tanto para la calibración y validación, excepto en algunas colas de presa. Además, los coeficientes de ganancia/pérdida del enrutamiento optimizados explicaron coherentemente las condiciones de campo en el área de estudio. Finalmente, los hallazgos de este estudio implican que las zonas con mayores caudales de descarga son propensas a grandes incertidumbres. El modelo puede ser de utilidad para los administradores de recursos hídricos involucrados en la gestión del agua en la provincia de Punjab.Water resource is being stressed due to increasing levels of social demands, particularly
in emerging and least developed nations. The arid and agro-based country of Pakistan
is highly dependent on Indus Basin Irrigation System (IBIS), one of the biggest contiguous
irrigation networks in the world, mainly fed by the Indus River, and its Eastern
tributaries Jhelum, Chenab, Ravi, and Sutlej. With limited water resources, irrigated
agriculture needs to improve its efficiency and equitable distribution. This study aims to
develop a flexible network model that involves a series of nodes interconnected via links
to characterize the Punjab irrigation within the IBIS system. The model is calibrated
by using Bayesian Monte Carlo method, where available knowledge about gain/loss parameters
is updated with the information in observed data.
After a rigorous calibration and validation, the model performance was assessed through
the use of the coefficient of determination (R2), Nash–Sutcliffe Efficiency (NSE), Kling-
Gupta Efficiency (KGE), and Percent bias (PBIAS). The overall results of the proposed
network model were acceptable for both calibration and validation periods, except in
some particular barrage tails. Nevertheless, due to the complexity of the irrigation network
and the simultaneous calibration for the entire system, the model behavior is considered
satisfactory. The optimized routing gain/loss coefficients coherently explained
the field conditions in the study area.
The findings in this study imply that zones with higher flow discharges are prone to large
uncertainties. In addition, posterior probability distributions of gain/loss coefficients
suggest an adequate identification of the parameter uncertainties, with changes in the
prior probability distributions. It also demonstrates how a selection of prior distribution
bounds and model parameters could improve the reliability and robustness of the model.
The model would be helpful to water resource managers involved in agricultural water
management in Punjab province. However, the utility of the model should be taken
with great care because there are still uncertainties in the modeling results due to the
conceptual nature and the quality of input data.Perú. Programa Nacional de Becas y Crédito Educativo (Pronabec). Beca Presidente de la RepúblicaTesis de maestrí
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Ancillary services from wind and solar energy in modern power grids: A comprehensive review and simulation study
Full text linkRenewable energy sources like wind and solar have increased demand for surplus power capacity. The demand is primarily fueled by the growing impact of forecasting errors associated with these intermittent energy sources. Implementing advanced control methods for automatic generation control (AGC) is essential to integrate wind and solar power with conventional generation sources to balance the power system and reduce reliance on traditional reserves. Therefore, this paper comprehensively overviews solar and wind energy integration in the AGC framework to provide optimal grid ancillary services. Initially, the paper presents an overview of the basic equations used to integrate reserve power from the photovoltaic (PV) system by employing the de-loading strategy. Subsequently, a comprehensive review is conducted on integrating the PV system in AGC strategies to provide grid ancillary services. The study also analyzes the contribution of wind power in AGC services using relevant equations and past practices. The paper presents a real-time dynamic control strategy to optimize the dispatch of the AGC unit by integrating the operating reserves from wind energy systems in conjunction with thermal power systems. The study simulates an 8-bus, 5-machine model using the Dig-SILENT Power Factory. The findings reveal that utilizing operating reserves from wind power can significantly reduce large-scale forecasting errors in massively renewable energy resources (RES) integrated power systems, thereby ensuring the necessary system operational security and reducing the reliance on traditional generating units
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