Thermal expansion behavior of LDEF metal matrix composites

The thermal expansion behavior of Long Duration Exposure Facility (LDEF) metal matrix composite materials was studied by (1) analyzing the flight data that was recorded on orbit to determine the effects of orbital time and heating/cooling rates on the performance of the composite materials, and (2) characterizing and comparing the thermal expansion behavior of post-flight LDEF and lab-control samples. The flight data revealed that structures in space are subjected to nonuniform temperature distributions, and thermal conductivity of a material is an important factor in establishing a uniform temperature distribution and avoiding thermal distortion. The flight and laboratory data showed that both Gr/Al and Gr/Mg composites were stabilized after prolonged thermal cycling on orbit. However, Gr/Al composites showed more stable thermal expansion behavior than Gr/Mg composites and offer advantages for space structures particularly where very tight thermal stability requirements in addition to high material performance must be met

The Need for a Change in Assessing Non-English Major Students at the Tertiary Level from Teachers’ Perspectives

Assessment is one of the six main components of an English as a foreign language (EFL) curriculum. It plays an important role in language education. Having the right techniques to assess students certainly supports learning. However, whether an institution or a department has an appropriate policy of assessing students, and a teacher has effective assessment techniques or not needs to be investigated through teachers’ opinions as well as real classroom observation. This paper aimed to explore how non-English major students were assessed regarding classroom assessment and achievement tests and whether the applied assessment techniques were effective or not. This study was conducted at the tertiary level through the use of two instruments: “open-response questionnaire” with six experienced EFL teachers and observations of six classes at three universities in Ho Chi Minh City, Vietnam. The findings revealed that very few classroom assessment techniques were used during the class and achievement tests did not meet their qualities such as validity and authenticity. The findings of the study provide administrators and EFL teachers with both theoretical and practical implications in student learning assessments at the tertiary level in Vietnam

Factors Affecting Task-Based Language Teaching from Teachers’ Perspectives

Teachers play the most important part in the application of a new method or approach in English language education. However, whether they implement the method successfully or not depends on various factors. This paper aims to explore the factors that affect English as a foreign language (EFL) teachers’ implementation of task-based language teaching (TBLT) at the tertiary level through the use of two instruments: “focus-groups” with five experienced EFL teachers and interviews with ten individual teachers at five universities in Ho Chi Minh City, Vietnam. The findings revealed that factors affecting teachers’ implementation of TBLT include external factors such as time allocation, testing, students’ motivation and English proficiency and textbooks, and internal factors such as teachers’ experience, knowledge about TBLT, English proficiency, and ability to use technology. The findings of the study provide EFL curriculum designers and teachers with both theoretical and practical implications in the implementation of TBLT at the tertiary level in Vietnam

Semantics-based approach for generating partial views from linked life-cycle highway project data

The purpose of this dissertation is to develop methods that can assist data integration and extraction from heterogeneous sources generated throughout the life-cycle of a highway project. In the era of computerized technologies, project data is largely available in digital format. Due to the fragmented nature of the civil infrastructure sector, digital data are created and managed separately by different project actors in proprietary data warehouses. The differences in the data structure and semantics greatly hinder the exchange and fully reuse of digital project data. In order to address those issues, this dissertation carries out the following three individual studies. The first study aims to develop a framework for interconnecting heterogeneous life cycle project data into an unified and linked data space. This is an ontology-based framework that consists of two phases: (1) translating proprietary datasets into homogeneous RDF data graphs; and (2) connecting separate data networks to each other. Three domain ontologies for design, construction, and asset condition survey phases are developed to support data transformation. A merged ontology that integrates the domain ontologies is constructed to provide guidance on how to connect data nodes from domain graphs. The second study is to deal with the terminology inconsistency between data sources. An automated method is developed that employs Natural Language Processing (NLP) and machine learning techniques to support constructing a domain specific lexicon from design manuals. The method utilizes pattern rules to extract technical terms from texts and learns their representation vectors using a neural network based word embedding approach. The study also includes the development of an integrated method of minimal-supervised machine learning, clustering analysis, and word vectors, for computing the term semantics and classifying the relations between terms in the target lexicon. In the last study, a data retrieval technique for extracting subsets of an XML civil data schema is designed and tested. The algorithm takes a keyword input of the end user and returns a ranked list of the most relevant XML branches. This study utilizes a lexicon of the highway domain generated from the second study to analyze the semantics of the end user keywords. A context-based similarity measure is introduced to evaluate the relevance between a certain branch in the source schema and the user query. The methods and algorithms resulting from this research were tested using case studies and empirical experiments. The results indicate that the study successfully address the heterogeneity in the structure and terminology of data and enable a fast extraction of sub-models of data. The study is expected to enhance the efficiency in reusing digital data generated throughout the project life-cycle, and contribute to the success in transitioning from paper-based to digital project delivery for civil infrastructure projects

Electrochemical reduction of CO2 to methanol

An efficient method to convert CO2 to fuels using renewable energy could displace crude oil without increasing CO2 emission and provide high-density energy storage reservoirs similar to liquid fuels or batteries. Although photoelectrochemical conversion of CO2 is possible, solar-to-fuel efficiencies are lower than the combination of conventional photovoltaics (up to 40% efficiency) and electrochemical cells (up to 80% Faradaic efficiency). In the electrochemical case, electrical energy from renewable sources may be converted to hydrocarbons or alcohols using electrocatalysts. The direct reduction of CO2 to CH3OH is known to occur at several types of electrocatalysts including oxidized Cu electrodes. In this thesis, we first examine the yield behavior of an electrodeposited cuprous oxide thin film and explore relationships between surface chemistry and reaction behavior relative to air-oxidized and anodized Cu electrodes. CH3OH yields and Faradaic efficiencies observed at cuprous oxide electrodes are remarkably higher than air-oxidized or anodized Cu electrodes suggesting Cu(I) species may play a critical role in selectivity to CH3OH. Experimental results also show CH3OH yields are dynamic and the copper oxides are reduced to metallic Cu in a simultaneous process. In order to improve CH3OH activity and electrode surface’s stability, single crystal ZnO (10-10) is considered as a support since ZnO support are well known for methanol synthesis in an industrial hydrogenation reaction scale. Although experimental conditions pose challenging barriers to repeatability, Infrared Spectroscopy and yields suggest the oxide may provide stable surfaces with selectivity to CH3OH. Yield behavior is discussed in comparison with photoelectrochemical and hydrogenation reactions where the improved stability of Cu(I) species may allow relatively constant CH3OH generation

PROBLEMS AND SOLUTIONS OF USING GROUP DISCUSSION ACTIVITIES IN GENERAL ENGLISH CLASSES AT DONG NAI TECHNOLOGY UNIVERSITY, VIETNAM

The paper discusses the current state and solutions of using group discussions in general English classes at Dong Nai University of Technology. It shows that using group discussions in English speaking classes is a very active and effective teaching and learning method. However, some teachers still do not understand how to deploy group work for their students to bring the best effect. Besides, many students still face some difficulties when participating in group discussions, there are still shy students who do not dare to express their personal opinions in front of the group; rely on other group members or use Vietnamese too much in the discussion process. At the same time, the paper also points out practical solutions, appropriate to improve the problems that both teachers and students are facing during group discussions. From there, teachers can deploy and organize group discussion activities more effectively; students can be more confident during group discussions.  Article visualizations

PCB CONCENTRATIONS IN SQUID, BLOOD COCKLE, SNAIL, MUSSEL AND PORK IN SOUTH-EASTERN PROVINCES OF SOUTH VIETNAM

Joint Research on Environmental Science and Technology for the Eart

PRELIMINARY SURVEY OF ARSENIC CONCENTRATIONS IN WATERS OF DIFFERENT SOURCES IN HOCHIMINH CITY AND OTHER PROVINCES

Joint Research on Environmental Science and Technology for the Eart

Some Issues Regarding the New Rural Development Program in Vietnam

The research focuses on presenting and analyzing several key concepts related to the New Rural Development Program in Vietnam. The presentation begins by defining crucial terms such as rural and new rural in Vietnam. Additionally, the article outlines the legal foundations and the government's target programs for building new rural areas, while discussing the necessity of constructing new rural areas in the current developmental context. This is a detailed and comprehensive article, offering readers an overview of the history and content of this program in enhancing the quality of life in rural Vietnam