91 research outputs found

    Mathematical aspects of catalyst positioning in Lithium/Air Batteries

    Get PDF
    Lithium/air batteries has been taken interest by many scientists over the last years. The catalyst positioning problem describing the porous cathode during the discharge process is concerned in the research of optimizing the capacity of Lithium/air batteries. During discharge process, there is a critical issue: the discharge oxygen reduction products is insoluble in the organic electrolytes. This clogs the oxygen entrance to the pore to be reacted with Lithium ions and limits the capacity of the batteries by narrowing the active surface inside the pore. The dynamics of the discharge process is described by the initial mixed boundary value problem for two one-dimensional partial differentiable equations. The two variables of the system are the pore radius inside the cathode and the Oxygen concentration at certain coordinate and time. The subject of the thesis is to investigate some catalyst positioning models and to maximize the free volume of the pore after pore clogging by the deposited discharged products. We aim at the following fields: First, we research analytically the forward model describing continuous catalyst positioning in Li/air batteries: well-posedness of the problems, the Fr echet differentiability of the pore radius and the oxygen concentration with respect to catalytic function in some spaces. Second, we present optimization problems and analyze the sensitivity and adjoint method to solve them. Finally, some numerical methods are carried out to solve the forward problems and some numerical approach for solving optimization problem are also examined to illustrate the theoretical results

    AUTHENTIC ASSESSMENT: A REAL LIFE APPROACH TO WRITING SKILL DEVELOPMENT

    Get PDF
     Since assessment is an indispensable part of education, curriculum makers, educators and teachers have engaged in an ongoing discussion of how to address student performance. A variety of assessments including both short-term and long-term ones can be applied during or at the end of the learning process. Among such types, authentic assessment is a prominent approach. This paper is going to advocate authentic assessments as it fosters students' growth and teachers' pedagogical strategies. In addition, it helps to reach the goals of educational practices through the authenticity of equity and innovation when students actively seek their own ways to appreciate what they have learnt. Particularly, in a writing skills class, learners can take this opportunity to improve step by step their own proficiency in the use of written words. The paper, hence, discusses how authentic assessment can be applied to develop college students' writing through classroom observation and a set of semi-structured interviews. The result of the study revealed that using authentic assessment is an effective strategy for enhancing students’ interest in writing process and writing task fulfillment. Students would find it easier to become skillful writers at their English levels. The study, therefore, recommends more uses of authentic assessment in teaching writing skills as well as in teaching and learning the English language in general

    3-Point++: a new Technique for 3D Manipulation of Virtual Objects

    Get PDF
    International audienceManipulation in immersive Virtual Environments (VEs) is often difficult and inaccurate because humans have difficulty in performing precise positioning tasks or in keeping the hand motionless in a particular position without any help of external devices or haptic feedback. To address this problem, we propose a set of four manipulation points attached to objects (called a 3-Point++ tool, including three handle points and their barycenter), by which users can control and adjust the position of objects precisely. By determining the relative position between the 3-Point++ tool and the objects, and by defining different states of each manipulation point (called locked/unlocked or inactive/active), these points can be freely configured to be adaptable and flexible to enable users to manipulate objects of varying sizes in many kinds of positioning scenarios

    Guiding Techniques for Collaborative Exploration in Multi-Scale Shared Virtual Environments

    Get PDF
    International audienceExploration of large-scale 3D Virtual Environments (VEs) is difficult because of lack of familiarity with complex virtual worlds, lack of spatial information that can be offered to users and lack of sensory (visual, auditory, locomotive) details compared to exploration of real environments. To address this problem, we present a set of metaphors for assisting users in collaborative navigation to perform common exploration tasks in shared collaborative virtual environments. Our propositions consist in three guiding techniques in the form of navigation aids to enable one or several users (called helping user(s)) to help one main user (called exploring user) to explore the VE efficiently. These three techniques consist in drawing directional arrows, lighting up path to follow, and orienting a compass to show a direction to the exploring user. All the three techniques are generic so they can be used for any kind of 3D VE, and they do not affect the main structure of the VE so its integrity is guaranteed. To compare the efficiency of these three guiding techniques, we have conducted an experimental study of a collaborative task whose aim was to find hidden target objects in a complex and multi-scale shared 3D VE. Our results show that although the directional arrows and compass surpassed the light source for the navigation task, these three techniques are completely appropriate for guiding a user in 3D complex VEs

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

    Get PDF
    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

    THE IMPACT OF INNOVATION ON ECONOMIC GROWTH: THE SPILLOVER EFFECT OF FOREIGN DIRECT INVESTMENT

    Get PDF
    Purpose of the study: Innovation is seen as the key to improving quality and productivity, thereby promoting competition and economic growth. This study analyzes the impact of innovation on economic growth through various measures, such as research and development spending, the number of researchers, number of patents as well as trademark registrations. Research results are evidence to recommend policies for intellectual-based economic growth. Methodology: Literature review and empirical analysis conducted in the study. The empirical method is a two-step System Generalize Methods of Moments (GMM), aiming at reliable results. Accessing the World Bank Database, research data from 64 developed and developing countries are collected from 2006 to 2014. Main Findings: The empirical findings show that innovation plays a crucial contribution in promoting economic growth, similar to national openness and government spending on education. This study also finds a positive impact on foreign investment flows and their spillover role in enhancing the correlation between innovation and economic growth. Applications of this study: The findings of this study focus on the contributions of innovation, foreign direct investment inflows, and other macro factors that can be enforced to improve economic growth by policymakers. Novelty/Originality of this study: The study uses different measures of innovation, including inputs such as the number of researchers, research and development expenditure, and outputs as the number of patents and number of trademark registrations. Empirical findings are found consistently, thus confirming that innovation is very important for economic growth. The study also shows convincing evidence confirming the positive contribution of foreign direct investment as well as its spillover effect on innovation and economic growth

    Genetic Diversity and Population Structure of Canarium tramdenum Dai and Yakovl. in Northern Vietnam

    Get PDF
    Canarium tramdenum occurs naturally in subtropical and tropical regions of Indochina and China. The wood is used for making high quality furniture and the fruit and leaves are used in traditional medicine. However, a lack of information on genetic diversity and population structure has handicapped the genetic conservation and domestication of this high-value species. This study evaluated genetic variation within and among four C. tramdenum populations. Sixty individuals were collected from four natural populations in Vietnam in the provinces of Ninhbinh, Bacgiang, Nghean, and Backan. Genetic diversity and genetic structure were determined using 20 ISSR markers. A total of 192 DNA fragments with sizes ranging from 110 bp to 3,000 bp were detected, of which 154 segments (80.2%) were polymorphic and 38 segments (19.8%) were monomorphic. The ISSR data indicated a moderate degree of genetic diversity for the species (h = 0.252). The four populations were separated into three genetic clusters with low levels of genetic distance between them. AMOVA result showed that most (78%) of the genetic variation was within the populations. The moderate to high genetic diversity of C. tramdenum and the low genetic differentiation among populations suggested that all existing natural populations in the particular regions needed to be preserved to protect the genetic diversity of this species

    The Effect of Monetary Instrument of Islamic Banking Financing Channel Towards The Economic Growth in Indonesia

    Get PDF
    Monetary policy is closely related to activities to achieve economic growth, which eventually gives welfare to the community. This study aims to analyze the description of the transmission flow of financing channels, the effect of monetary policy instruments, and their effectiveness to achieve economic growth. The variables used are Islamic Banking Finance (FIN), return of Sharia Bank Indonesia Certificate (SBIS), return of PUAS, and Industrial Production Index (IPI). This study used Vector Error Correction Model (VECM) to determine short- and long-term relationships using the time series data. First, the result of the study showed that the transmission flow could not be identified clearly, because the flow stopped in FIN, and it could not affect IPI, according to the Granger Causality test. Second, the result of VECM estimation showed that all variables only affected long term period and did not affect the short-term period. Third, monetary policy transmission of Islamic banking financing channel was not effective enough, which was proven with the result of IRF simulation, which showed that the effect of shock on financing channel variable (FIN) towards IPI was subsided and stable in the 10th period later. Meanwhile, the result of the FEVD simulation showed that the financing channel variable (FIN) only gave a contribution of as much as 0.14 percent towards IPI. The contribution and policy implications are also discussed in this study

    Examining the effects of lead on the life of larval zebrafish (1-7 days old)

    Get PDF
    Lead (Pb) is a toxic metal and and can cause variety of disorders and effect on neu-ronal function and neurodevelopment. Using zebrafish as a model, the aim of this study was to evaluate the effects of concentrations of Pb2+ on the life of zebrafish larvae (from 1 to 7 days old)yesBelgorod State Universit

    Factors affecting employee performance through a mediation of job satisfaction. An empirical study of hospitality industry in Ho Chi Minh City, Vietnam

    Get PDF
    The research was conducted to explore the relationships between the factors of career development, team spirit, relationship at work, compensation and benefit, working environment, job stress and the factor of employee performance through a mediation of job satisfaction in Hospitality Industry in Ho Chi Minh City, Vietnam. Based on previous theoretical and empirical studies, the research conceptual framework and hypotheses were constructed. The primary data was collected from a questionnaire survey with 711 respondents. Multiple regression and Path analyses were conducted to test the research hypotheses, the results showed that career development, team spirit, relationship at work, compensation and benefit, working environment, and employee job satisfaction positively and directly impacted on employee performance. In addition, all factors indirectly influenced employee performance through job satisfaction. Hence, organizations operating in hospitality industry in Ho Chi Minh City should understand better employee expectations to efficiently and effectively improve and manage their human resources
    corecore