62 research outputs found
Impact of the usage of Vietnamese consonant-vowel (CV) structure on the intelligibility of Vietnamese speakers of English
This paper reports on findings from an investigation into the potential impact of the mother tongue of 50 Vietnamese adult EFL learners on their English intelligibility, with a particular focus on CV (consonant - vowel) syllable structure. The data from this quantitative study indicate that participants applied the Vietnamese CV syllable structure (open syllables CV.V) to the pronunciation of English CVC syllable structure (closed syllables CVC.V particularly in polysyllabic words and words with CVL (consonant – vowel – lateral) structure, potentially affecting speech intelligibility. These outcomes contribute to research on EFL speakers’ intelligibility
A RESEARCH ON MULTI-OBJECTIVE OPTIMIZATION OF THE GRINDING PROCESS USING SEGMENTED GRINDING WHEEL BY TAGUCHI-DEAR METHOD
In this study, the mutil-objective optimization was applied for the surface grinding process of SAE420 steel. The aluminum oxide grinding wheels that were grooved by 15 grooves, 18 grooves, and 20 grooves were used in the experimental process. The Taguchi method was applied to design the experimental matrix. Four input parameters that were chosen for each experiment were the number of grooves in cylinder surface of grinding wheel, workpiece velocity, feed rate, and cutting depth. Four output parameters that were measured for each experimental were the machining surface roughness, the system vibrations in the three directions (X, Y, Z). The DEAR technique was applied to determine the values of the input parameters to obtaine the minimum values of machining surface roughness and vibrations in three directions. By using this technique, the optimum values of grinding wheel groove number, workpiece velocity, feed-rate, cutting depth were 18 grooves, 15 m/min, 2 mm/stroke, and 0.005 mm, respectively. The verified experimental was performed by using the optimum values of input parameters. The validation results of surface roughness and vibrations in X, Y, Z directions were 0.826 (µm), 0.531 (µm), 0.549 (µm), and 0. 646 (µm), respectively. These results were great improved in comparing to the normal experimental results. Taguchi method and DEAR technique can be applied to improve the quality of grinding surface and reduce the vibrations of the technology system to restrain the increasing of the cutting forces in the grinding process. Finally, the research direction was also proposed in this stud
Deep heterogeneous ensemble.
In recent years, deep neural networks (DNNs) have emerged as a powerful technique in many areas of machine learning. Although DNNs have achieved great breakthrough in processing images, video, audio and text, it also has some limitations such as needing a large number of labeled data for training and having a large number of parameters. Ensemble learning, meanwhile, provides a learning model by combining many different classifiers such that an ensemble of classifiers is better than using single classifier. In this study, we propose a deep ensemble framework called Deep Heterogeneous Ensemble (DHE) for supervised learning tasks. In each layer of our algorithm, the input data is passed through a feature selection method to remove irrelevant features and prevent overfitting. The cross-validation with K learning algorithms is applied to the selected data, in order to obtain the meta-data and the K base classifiers for the next layer. In this way, one layer will output the meta-data as the input data for the next layer, the base classifiers, and the indices of the selected meta-data. A combining algorithm is then applied on the meta-data of the last layer to obtain the final class prediction. Experiments on 30 datasets confirm that the proposed DHE is better than a number of well-known benchmark algorithms
Prism-Based Sunlight Concentrator Layout: A Genetic Algorithm Solution
Solar energy is a promising source of energy because it is abundant and harmless to the environment. One of the critical issues involving solar energy is the layout design of sunlight concentrators. This study presents a computational method for reforming the layout of a special sunlight concentrator that consists of a set of prisms to significantly enhance its light intensity. Sunlight movement toward the prisms is modeled, and a genetic algorithm is applied to find a good concentrator layout. Experiments under various light transmission rates validate the performance of our proposed method. The proposed optimal sunlight concentrator layout improves the intensity of light by 55%
Design and fabrication of the trapezoidal electrostatic comb-drive actuator
This paper reports the design, fabrication and characterization process of the trapezoidal Electrostatic Comb-drive Actuator (ECA) with the slope angle α=20. Together with the trapezoidal ones, the rectangular ECA with identical dimension was also designed and fabricated for comparison purpose. In order to reduce calculating deviation, the fringing effect was also taken into consider while carrying out theoretical analysis. The obtained results pointed out the fact, that the trapezoidal ECA excels the rectangular ones with the same numbers of teeth in electrostatic force and displacement generation, while requires relatively low driving voltage. But it is also observed that with higher driving voltage (larger than 50V), the trapezoidal ECA starts to lose its stability (the lateral pull-in phenomenon occurs)
Assessments of Use of Blended Radar–Numerical Weather Prediction Product in Short-Range Warning of Intense Rainstorms in Localized Systems (SWIRLS) for Quantitative Precipitation Forecast of Tropical Cyclone Landfall on Vietnam’s Coast
A Simplified Double-Bundle Anterior Cruciate Ligament Reconstruction by the Three-Inside Technique With Two Suspension Buttons and One Interference Screw
In comparison with the single-bundle technique, double-bundle anterior cruciate ligament (ACL) reconstruction has proven its superiority regarding biomechanical studies and clinical outcomes in both rotational knee stability and anterior translation function. However, the complexity and risk of complications remain a great concern for the orthopaedic surgeon performing double-bundle ACL reconstruction. We present a simplified double-bundle ACL reconstruction by the 3-inside technique with 2 suspension buttons and 1 interference screw. The semitendinosus tendon is tripled to be the anteromedial (AM) bundle, whereas the gracilis is doubled for the posterolateral (PL) bundle. We perform a 3-socket approach with an inside-out femoral tunnel for the AM bundle, an outside-in femoral tunnel for the PL bundle, and a retrograde tibial socket for the tibial bundle. Thus, this technique is, simply, a combination of 2 procedures: one single all-inside method (for the AM bundle) and one outside-in method (for the PL bundle), with which most arthroscopic surgeons are familiar. The AM and PL bundles are fixed at 30° and 45°, respectively, using 2 suspension buttons and 1 interference screw. Our simplified technique could reduce surgical costs and minimize complications while maintaining isometric position and appropriate graft size for each patient
The role of classroom observation in the development and assessment of schoolteachers in Vietnam: a review of national policy and research
This paper focuses on the role of classroom observation in the development and assessment of schoolteachers in Vietnam through a narrative review of current policy and cognate research literature. The overall aim of this review was twofold. Firstly, to contribute to a growing bank of Vietnam-based studies to maximise the value of the insights from this scholarly work into recent policy reforms on teachers’ professional development in Vietnam. Secondly, to widen access and exposure to published work on the topic in Vietnamese that is not readily accessible to English-speaking scholars. This review revealed a long history and engrained culture of using observation as a teacher performance evaluation tool. In recent years, there have been policy reforms and research studies that have repositioned observation as a tool for teacher learning and development. However, the implementation of these reforms has been inconsistent across Vietnam, along with recent reform having encountered resistance from a culture of compliance in schools. This paper identifies some of the key issues that policy makers and educational leaders need to address in practice in order to ensure the effective and meaningful implementation of the reforms relating to the use of observation for learning and developmental purposes
Sorting or supporting teachers? An exploration of the imbalanced role of classroom observation in the development and assessment of Vietnamese secondary schoolteachers
In 2018, Vietnam’s National Teacher Education Programme established a new framework for schoolteachers’ professional development. Classroom observation was the dominant method used for teacher monitoring, assessment and development. This paper explores the use and impact of current classroom observation policy and practice on novice teachers in Vietnamese secondary schools. Our study draws on qualitative data from 35 semi-structured interviews across four provinces. Our findings revealed ongoing policy-practice tensions, with the prioritisation and dominance of classroom observation as an assessment tool for sorting rather than supporting teachers. These tensions were indicative of a wider policy-practice disconnect enshrined in recent reform by the Ministry of Education and Training that advocated the adoption of lesson study as the preferred national approach in schools. However, the experiences of our participants reflected a very different picture in practice that reinforced traditional hierarchies of power associated with evaluative models of observation that are designed to standardise and rank teachers’ classroom performance rather than develop the quality of teaching. Instead of the more collaborative and collegial ethos typically associated with inquiry-based approaches like lesson study, observation was being used largely as a high-stakes assessment, resulting in increased levels of anxiety and stress among teachers
Farming systems in the sandy area of the Thua Thien Hue Province, Central Vietnam, survey of socio-economic situation and constraints identified by farmers
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