143 resultados para Viêt-nam


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This paper considers time-delay systems with bounded disturbances. We study a new problem of finding an upper bound of an absolute value function of any given linear functional of the state vector starting from the origin of the system. Based on the Lyapunov-Krasovskii method combining with the recent Wirtinger-based integral inequality that has just been proposed by Seuret & Gouaisbaut (2013. Wirtinger-based integral inequality: application to time-delay systems. Automatica, 49, 2860-2866), sufficient conditions for the existence of an upper bound of the function are derived. The obtained results are shown to be more effective than those adapted from the existing works on reachable set bounding. Furthermore, the obtained results are applied to refine existing ellipsoidal bounds of the reachable sets. The effectiveness of the obtained results is illustrated by two numerical examples.

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In this paper, we derive a new inequality, which encompasses the discrete Jensen inequality. The new inequality is applied to analyze stability of linear discrete systems with an interval time-varying delay and a less conservative stability condition is obtained. Two numerical examples are given to show the effectiveness of the obtained stability condition.

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The Longitudinal Teacher Education Workforce Study (LTEWS) investigated the career progression of graduate teachers from teacher education into teaching employment in all states and territories across Australia in 2012 and the first half of 2013, and tracked their perceptions, over time, of the relevance and effectiveness of their teacher education programs. Specifically, it investigated: The career progression of the 2011 teacher education graduates from teacher education into, andpossible exit from, teaching employment, including their utilisation into teaching, their retention and attrition in teaching in their early years, and their geographic and schools sector mobility; and, The views of teacher education graduates over time on the relevance and effectiveness of their teacher education for their teaching employment, including the relationship between their views of their teacher education and their early career teaching career.LTEWS was conducted concurrently with the Studying the Effectiveness of Teacher Education (SETE) project, which is a three-year project investigating these issues in Queensland and Victoria. SETE is funded by the Australian Research Council, the Victorian Department of Education and Early Childhood Development (DEECD), the Queensland Department of Education, Training and Employment (QDETE), the Victorian Institute of Teaching (VIT), and the Queensland College of Teachers (QCT). LTEWS focused on data collection in states and territories other than Queensland and Victoria. The findings from the SETE study were incorporated with the LTEWS findings to provide a national data set.

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Linear systems with interval time-varying delay and unknown-but-bounded disturbances are considered in this paper. We study the problem of finding outer bound of forwards reachable sets and inter bound of backwards reachable sets of the system. Firstly, two definitions on forwards and backwards reachable sets, where initial state vectors are not necessary to be equal to zero, are introduced. Then, by using the Lyapunov-Krasovskii method, two sufficient conditions for the existence of: (i) the smallest possible outer bound of forwards reachable sets; and (ii) the largest possible inter bound of backwards reachable sets, are derived. These conditions are presented in terms of linear matrix inequalities with two parameters need to tuned, which therefore can be efficiently solved by combining existing convex optimization algorithms with a two-dimensional search method to obtain optimal bounds. Lastly, the obtained results are illustrated by four numerical examples.

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Abstract
This paper presents new discrete inequalities for single summation and double summation. These inequalities are based on multiple auxiliary functions and include the Jensen discrete inequality and the discrete Wirtinger-based inequality as special cases. An application of these discrete inequalities to analyse stability of linear discrete systems with an interval time-varying delay is studied and a less conservative stability condition is obtained. Three numerical examples are given to show the effectiveness of the obtained stability condition.

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We adapted/developed and examined the test–retest reliability and internal consistency of eight parent-report measures of home and neighborhood environmental correlates of physical activity appropriate for Chinese preschool-aged children and their parents/primary caregivers living in densely populated urban environments. This study consisted of a qualitative (cognitive interviews) and a quantitative (test–retest reliability) component. Chinese versions of the measures were pilot-tested on 20 parents of Hong Kong preschool-aged children using cognitive interviews. Measures were then administered to 61 parents twice, 1 week apart. Test–retest reliability and internal consistency were computed. Except for two items, the test–retest reliability of items and scale summary scores ranged from moderate to excellent. The internal consistency of the measures exceeded recommended minimal values (Cronbach’s α >.70). The parent-report measures examined in this study are potentially appropriate for use in investigations of environmental correlates of the physical activity of Chinese preschool-aged children living in densely populated urban environments. However, their predictive validity with respect to Chinese preschool-aged children’s physical activity needs to be assessed in future studies.

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Mitochondrial dysfunction, ubiquitin-proteasomal system impairment and excitotoxicity occur during the injury and death of neurons in neurodegenerative conditions. The aim of this work was to elucidate the cellular mechanisms that are universally altered by these conditions. Through overlapping expression profiles of rotenone-, lactacystin- and N-methyl-D-aspartate-treated cortical neurons, we have identified three affected biological processes that are commonly affected; oxidative stress, dysfunction of calcium signalling and inhibition of the autophagic-lysosomal pathway. These data provides many opportunities for therapeutic intervention in neurodegenerative conditions, where mitochondrial dysfunction, proteasomal inhibition and excitotoxicity are evident.

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Boron nitride nanotubes (BNNTs) have been studied as a field emission material due to their unique and excellent properties such as high oxidation resistance and negative electron affinity. However, field emission properties of BNNT field emitters were rarely reported until now because it is difficult to synthesize high purity BNNTs and fabricate stable BNNT field emitters. Here, we report high field emission properties from BNNT field emitters fabricated on a tungsten rod.