A weighted residual relationship for the contact problem with Coulomb friction

International audienceIn this work, a weighted residual relationship is proposed as an extension of the standard virtual work principle to deal with the large deformation contact problem with Coulomb friction. This weak form is a mixed relationship involving the displacements and the multipliers defined on the reference contact surface of the contactor and is shown to be equivalent to the strong form of the initial/boundary value contact problem. The discretization in space by means of the finite element method is carried out on the mixed relationship in a simple way in order to obtain the semi-discrete equation system. The contact tangent stiffness is derived and numerical examples are presented to assess the efficiency of the formulation. (c) 2009 Elsevier Ltd. All rights reserved

A simple weak form for contact problems with Coulomb friction

This paper proposes a weak form for the contact problem with Coulomb friction, written as extension of the standard virtual work principle and involving both the displacements and the multipliers defined on the reference contact surface. The mixed relationship is shown to be equivalent to the strong form of the initial/boundary value contact problem, and it can be discretized by means of the finite element method in a simple way. Typical numerical examples are given to assess the efficiency of the formulation in statics and dynamics

Ecological Engineering and Restoration of Eroded Muddy Coasts in South East Asia: Knowledge Gaps and Recommendations

Ecological engineering (EE) was employed for developing strategies for stabilizing eroded muddy coasts (EMCs). However, there was a limited analysis of these EE strategies with respect to design, performance, and lessons learned. This study employed a critical review for addressing the limitations. There were four EE models designed with different restoration interventions for stabilizing EMCs. The models using active interventions have not been cost-effective in controlling erosion because the interventions failed to achieve their goals or were costly and unnecessary. Of the two passive intervention models, the one with structures constructed from onshore proved to be more cost-effective in terms of construction costs, the survival rate of transplanted seedlings, and levels of sea mud accumulation. Interventions with adequate consideration of the muddy coastal ecological processes and the ecological reasoning for the positioning of these interventions play a crucial role in stabilizing EMCs. A passive restoration model using gradually expanded interventions should be promoted in order to ensure sustainable management of EMCs in the future

Challenges of Implementing Outcome-Based Assessment in Vietnamese Higher Education – A Qualitative Inquiry

This qualitative study investigates the key challenges faced by university lecturers in implementing outcome-based assessments (OBA) in higher education institutions in Vietnam, a country currently undergoing significant educational transformation. Utilizing a qualitative research design, the study conducted semi-structured interviews with 15 lecturers from diverse academic fields in a institution. The data were thematically coded and interpreted through the lenses of Constructivism, Institutional Theory, and Diffusion of Innovations Theory. Nine major challenges emerged from the findings, including pedagogical hurdles, lack of training and resources, institutional constraints, and technological limitations. These challenges are contextualized within the existing theoretical frameworks and related literature. The study offers critical insights that are deeply rooted in cultural, institutional, and structural variables. These findings are pertinent for educators, administrators, and policymakers in Vietnam and potentially for those in similar educational settings, and they hold broader implications for professional development, institutional policies, technological infrastructure, and cultural shifts within the educational landscape

In-action reflective teaching in Vietnam: A qualitative exploration of practices, influences and implications

Reflective teaching plays a crucial role in the field of education though its intricacies in particular cultural contexts like Vietnam are still little understood. This study aims to investigate reflective teaching practices in more detail within the context of Vietnamese education.  This study used a qualitative methodology and semi-structured interviews with twelve Vietnamese teachers, each representing a different stage of their careers to shed light on the many forms of in-action reflective practices and their implementation, benefits, drawbacks and even cultural influences. The results of this in-depth investigation provided an overview of the wide range of in-action reflective practices that are actively used in the classroom.  The enhancement of adaptive teaching methodologies and the bolstering of student engagement are prominent among the many advantages that were noted.  Teaching in the Vietnamese context also presents unique challenges. Teachers often struggle with the demands of multitasking, the complexities of navigating uncertainties in real-time classroom scenarios   and the predominant challenge of managing large class sizes. Moreover, it was surprising to learn how many Vietnamese cultural, social   and educational factors influenced teacher understanding and use of in-action reflection.  The understanding of reflective teaching practices is enhanced by the research findings which also have broad implications for areas such as instructional strategies, teacher preparation programmes, academic research perspectives and even the development of educational policies.  The study strongly emphasizes the pressing need for more context-specific investigations into reflective teaching and underscores the indispensable role of reflection in fostering an environment conducive to effective teaching and learning

Trends in socioeconomic inequalities in full vaccination coverage among vietnamese children aged 12–23 months, 2000–2014: Evidence for mitigating disparities in vaccination

There has been no report on the situation of socioeconomic inequalities in the full vaccination coverage among Vietnamese children. This study aims to assess the trends and changes in the socioeconomic inequalities in the full vaccination coverage among Vietnamese children aged 12–23 months from 2000 to 2014. Data were drawn from Multiple Indicator Cluster Surveys (2000, 2006, 2011, and 2014). Concentration index (CCI) and concentration curve (CC) were applied to quantify the degree of the socioeconomic inequalities in full immunization coverage. The prevalence of children fully receiving recommended vaccines was significantly improved during 2000–2014, yet, was still not being covered. The total CCI of full vaccination coverage gradually decreased from 2000 to 2014 (CCI: from 0.241 to 0.009). The CC increasingly became close to the equality line through the survey period, indicating the increasingly narrow gap in child full immunization amongst the poor and the rich. Vietnam witnessed a sharp decrease in socioeconomic inequality in the full vaccination coverage for over a decade. The next policies towards children from vulnerable populations (ethnic minority groups, living in rural areas, and having a mother with low education) belonging to lower socioeconomic groups may mitigate socioeconomic inequalities in full vaccination coverage. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Huy Nguyen” is provided in this record*

Multi-faceted identities of teacher assessors: A qualitative study in the Vietnamese educational context

Within the educational landscape of Vietnam, the professional identity of teachers when acting as assessors remains a comparatively uncharted domain and requires further explorations. Consequently, this qualitative investigation was initiated to delve deeper into the intricate identities Vietnamese teachers adopt in their capacities as assessors. Relying upon frameworks such as Constructivist Grounded Theory and Identity Theory, the study meticulously analyzed self-reported narratives from 15 tertiary lecturers based in Vietnam. Through this rigorous analysis, a spectrum of fifteen distinct identities was uncovered. These identities included “Gatekeepers of Knowledge and Competency”, “Nurturers”, “Diplomatists”, “Auditors”, “Confusian Sages”, “Innovators”, “Social Justice Advocators”, “Cultural Mediators”, “Emotional Anchors”, “Scalfolders”, “Technological Navigators”, “Lifelong Learners”, “Community Builders”, “Ethical Guardians”, and “Democratic Facilitators.” Intriguingly, these identities were not merely seen as additional layers to their professional duties; instead, they emerged as foundational components of teachers’ professional self-image. The forces molding these roles are diverse, encompassing deep-seated cultural values, prevailing educational paradigms, and personal lived experiences of educators. Unraveling these identities offers consequential implications for the broader educational sector. It underscores the imperative to holistically re-envision teacher training programs and assessment design, ensuring they resonate with the multifaceted roles educators play in steering both academic achievements and wider societal outcomes

CURRENT CULTURAL LIFESTYLE OF THE HMONG PEOPLE IN THE BORDER AREA OF CAO BANG PROVINCE, VIETNAM

The culture of ethnic minorities in general and the Hmong people in particular are an essential part of Vietnam's advanced culture, rich in ethnic characteristics. In the current process of international integration, the exchange and adaptation of cultural values from the outside world are both an objective necessity and a challenge. This process provides opportunities while, at the same time, posing challenges for preserving and promoting traditional cultural values. Additionally, the Hmong culture is also influenced by religious beliefs, specifically Protestantism, which accentuates cultural transformation. This has an impact on the stability and development of the cultural and social aspects, as well as the local and national security. Therefore, this article focuses on analyzing the current cultural lifestyle of the Hmong people in the border region of Cao Bang province. It aims to identify the issues that arise and propose solutions to preserve and promote the cultural values of this ethnic group under the influence of Protestantism. Simultaneously, it seeks to limit the emergence of negative factors contributing to the sustainable development of the border region of Cao Bang province

Common mutations in G6PD of Vietnamese-Kinh deficient patients

This study was conducted to identify the common mutations occurring within the G6PD gene in the G6PD - Vietnamese deficient patients, which may be the main causative mutations of the G6PD deficiency in Vietnamese-kinh. Sequencing was performed to detect mutations in the coding region of G6PD gene for 30 Vietnamese-Kinh G6PD deficient patients. Seven sets of primers were designed to amplify and sequenced 13 coding regions of G6PD gene. Seven known types of mutations were detected. Each patient had at least one mutation in his G6PD gene. The most common mutation is the silent mutation 1311C>T with frequency of 56.66%. With the high frequency, the 1311C>T mutations are suggested as potential markers for G6PD deficiency in Vietnamese-kinh population.Keywords: G6PD deficiency, Vietnamese-Kinh, 1311C>T, Viangchan, CantonAfrican Journal of Biotechnology Vol. 12(12), pp. 1318-132

A fuzzy finite element algorithm based on response surface method for free vibration analysis of structure

This paper introduces an improved response surface-based fuzzy finite element analysis of structural dynamics. The free vibration of structure is established using superposition method, so that fuzzy displacement responses can be presented as functions of fuzzy mode shapes and fuzzy natural frequencies. Instead of direct determination of these fuzzy quantities by modal analysis which will involve the calculation of the whole finite element model, the paper proposes a felicitous approach to design the response surface as surrogate model for the problem. In the design of the surrogate model, complete quadratic polynomials are selected with all fuzzy variables are transformed to standardized fuzzy variables. This methodology allows accurate determination of the fuzzy dynamic outputs, which is the major issue in response surface based techniques. The effectiveness of the proposed fuzzy finite element algorithm is illustrated through a numerical analysis of a linear two-storey shear frame structure