Who Drives Economic Reform in Vietnam’s Provinces?

The authors compare two provinces in the North and two in the South, observing how different alignments of interest influence the reform process. The research shows that in those provinces which are making most progress in economic reform, the private sector played an important role. Not against government but with government. There was no formal public-private coalition, but a dynamic existed of proactive government seeking input from the private sector, and the latter lobbying for and contributing to responsive and effective government. Both national and foreign enterprises played a role, but small enterprises tended to be marginalised from the process. PLEASE NOTE: This is a Research Summary of 'Who Drives Economic Reform in Vietnam’s Provinces?', IDS Research Report 76

Impacts of Economic Development on the Awareness of Cultural Preservation of Ethnic Minority People in the Border Region of Northern Vietnam

Purpose: The aim of this study is to examine how the Vietnamese government's economic development strategies affect ethnic minority people's knowledge of cultural preservation in the border area of Northern Vietnam.   Theoretical framework: The study focuses on three main driven factors of the awareness of cultural preservation that are economic changes, societal changes, and environmental changes from three economic fields: agriculture, industry, and trade and services.   Design/methodology/approach: The research sample was taken from ethnic minorities in Northern Vietnam's border area. For questionnaire administration, interviewees are selected at random from the population. Face-to-face, drop-off, and phone-calling approaches were used to disseminate the questionnaire. We received 544 completed returns out of 725 surveys sent out. The data was then cleaned and analyzed with SPSS 20 software using Partial Least Squares Structural Equation Modelling (PLS-SEM).   Findings: The results of a study of ethnic minority communities in seven provinces in Northern Vietnam's border region show that the development of agriculture, industry, trade and service significantly impacts ethnic minority people's awareness of cultural preservation issues due to environmental changes. In contrast, economic and sociological developments appear to have little influence on ethnic minority people's attention to cultural preservation. This phenomenon may be due to the long-term effects of economic and sociological changes, which mostly affect intangible cultural heritages. In contrast, environmental impats are felt swiftly and primarily on physical cultural heritages that can be seen.   Research, Practical & Social implications: The findings of the research provide policymakers with valuable insights on the effects of economic development on cultural preservation. The study's recommendations can inform policies that promote sustainable economic development while preserving the cultural heritage of ethnic minority communities.   Originality/value: The research focuses on the border region of Northern Vietnam, which is an area of strategic importance for economic development and cultural preservation. The study's unique focus on this region provides insights into the cultural and economic dynamics of a specific area that has not been extensively studied

Merosesquiterpenes from marine sponge Smenospongia cerebriformis

Using various chromatography methods, three merosesquiterpenes belonging to sesquiterpene quinone type, neodactyloquinone (1), dactyloquinone D (2), and dactyloquinone C (3) together with two indole derivatives indole-3-aldehyde (4) and indole-3-cacboxylic methyl ester (5) were isolated from the methanol extract of the Vietnamese marine sponge Smenospongia cerebriformis. Their structures were determined by 1D-, 2D-NMR spectra, HR-ESI-MS and in comparison with those reported in the literature. Keywords. Smenospongia cerebriformis, merosesquiterpene, sesquiterpene quinone, indole derivative

Virtual tool linking the micro/meso scales of a thermoplastic composite affected by hygrome-try and temperature for quasi-static loading

Les travaux de cette thèse se sont intéressés à l’obtention du comportement d’un composite sergé 2x2 verre/PA66 via un outil numérique basé sur une double homogénéisation : la première concerne les torons et la seconde le volume élémentaire représentatif du composite. A partir d’une campagne de caractérisation expérimentale sur le PA66, nous avons dans un premier temps identifié l’influence à la fois de l’hygrométrie et de la température sur le comportement de la matrice en quasi-statique. Ensuite, nous avons élaboré, implémenté et validé une loi de comportement isotrope élasto-plastique endommageable. Cette loi a servi à identifier par homogénéisation le comportement des torons en supposant un collage parfait des fibres et de la matrice ainsi qu’une homogénéité de l’eau dans le toron. Grâce à ces comportements identifiés et à l’élaboration d’une loi de comportement anisotrope élasto-plastique endommageable, nous avons pu déterminer les caractéristiques élastiques dans un premier temps et les comportements longitudinaux et en cisaillement dans un second temps. Les comparaisons aux résultats expérimentaux menés sur le composite offrent des résultats satisfaisants et permettent de penser que l’outil numérique développé, permettrait, à termes, d’aider à une conception rapide incluant ce genre de matériau en diminuant le nombre d’essais expérimentaux à faire. Des perspectives enfin sont proposées notamment pour l’extension aux comportements en dynamique (crash).The objective of this PhD thesis is to create a methodology to simulate the behavior of a 2x2 glass/PA66 twill composite using homogenization. To achieve this goal, we use two steps: first one is dedicated to represent the yarn behavior and the second one to represent the behavior of the composite RVE. An experimental characterization campaign about the PA66 has been done in order to quantify the influence of both hygrometry and temperature on the behavior of the matrix in quasi-static. Then, we formulated, implemented and validated an isotropic elasto-plastic damageable constitutive law. It was used to identify by homogenization the behavior of the yarns by assuming a perfect bonding of the fibers and the matrix as well as a water homogeneity inside the yarn. Thanks to the identified behavior of the yarns and by formulating a compatible constitutive law (anisotropic elasto-plastic damageable), we have determined for the woven composite on one hand the elastic properties and in the other hand the longitudinal/transversal and shear nonlinear behaviors. The comparisons of the numerical and experimental results offer satisfactory results. It provides good outlook in short-term in regard of structures design which include this type of woven composite materials. The main advantage of the methodology is to decrease the number of required experimental tests. Some outlook dedicated to crash studies are finally suggested

Elaboration d’un outil numérique reliant les échelles micro/méso d’un composite thermoplastique sensible à l’humidité et à la température en quasi-statique

The objective of this PhD thesis is to create a methodology to simulate the behavior of a 2x2 glass/PA66 twill composite using homogenization. To achieve this goal, we use two steps: first one is dedicated to represent the yarn behavior and the second one to represent the behavior of the composite RVE. An experimental characterization campaign about the PA66 has been done in order to quantify the influence of both hygrometry and temperature on the behavior of the matrix in quasi-static. Then, we formulated, implemented and validated an isotropic elasto-plastic damageable constitutive law. It was used to identify by homogenization the behavior of the yarns by assuming a perfect bonding of the fibers and the matrix as well as a water homogeneity inside the yarn. Thanks to the identified behavior of the yarns and by formulating a compatible constitutive law (anisotropic elasto-plastic damageable), we have determined for the woven composite on one hand the elastic properties and in the other hand the longitudinal/transversal and shear nonlinear behaviors. The comparisons of the numerical and experimental results offer satisfactory results. It provides good outlook in short-term in regard of structures design which include this type of woven composite materials. The main advantage of the methodology is to decrease the number of required experimental tests. Some outlook dedicated to crash studies are finally suggested.Les travaux de cette thèse se sont intéressés à l’obtention du comportement d’un composite sergé 2x2 verre/PA66 via un outil numérique basé sur une double homogénéisation : la première concerne les torons et la seconde le volume élémentaire représentatif du composite. A partir d’une campagne de caractérisation expérimentale sur le PA66, nous avons dans un premier temps identifié l’influence à la fois de l’hygrométrie et de la température sur le comportement de la matrice en quasi-statique. Ensuite, nous avons élaboré, implémenté et validé une loi de comportement isotrope élasto-plastique endommageable. Cette loi a servi à identifier par homogénéisation le comportement des torons en supposant un collage parfait des fibres et de la matrice ainsi qu’une homogénéité de l’eau dans le toron. Grâce à ces comportements identifiés et à l’élaboration d’une loi de comportement anisotrope élasto-plastique endommageable, nous avons pu déterminer les caractéristiques élastiques dans un premier temps et les comportements longitudinaux et en cisaillement dans un second temps. Les comparaisons aux résultats expérimentaux menés sur le composite offrent des résultats satisfaisants et permettent de penser que l’outil numérique développé, permettrait, à termes, d’aider à une conception rapide incluant ce genre de matériau en diminuant le nombre d’essais expérimentaux à faire. Des perspectives enfin sont proposées notamment pour l’extension aux comportements en dynamique (crash)

Numerical Analysis Concerning the Harmfulness of Crack Turbine Rotors Using a Multi-Scale Approach Based on a Dynamic Finite Element Method

International audienceThis work is placed in the context of the simulation of the behavior and the harmfulness of cracked rotors by Electricité de France (EDF) in order to evaluate its impact on the industrial system. Several numerical tools have been developed by the Research and Development Division of EDF and a feasibility study was conducted to prove its capacities to simulate the behavior of a rotor subject to a crack. Since the industrial context request fast response to such situation, the numerical simulation must be performed as quickly as possible. For this reason a multi-scale 1D-3D modeling has been proposed: the healthy part of the rotor is modeled by reduced Timoshenko beam finite elements since the part including the crack is modeled by 3D finite elements. The aim of the work is to prove the accuracy of this multi-scale approach, its feasibility and its CPU performance

Multiscale Homogenization of a glass-PA66 Fabric Composite Behavior for crash studies

International audienceIn the automotive industry, the taking into account of different environmental conditions is a major key because it assures the cars to be well designed for quite all over the world. The introduction of some composite materials such as woven thermoplastic composites then complexifies the task of the engineers because due the sensitivity of the matrix to both temperature and hygrometry; they have to manage long and expensive experimental testing. The aim of this paper is to present a numerical study based on a double homogenization in order to alleviate the constraints of experiment and let the engineers to quickly find some mechanical characteristics for their designs. First, we present the methodology and the constitutive laws (fiber and thermoplastic matrix) adapted to the first homogenization in relation with the tows. The matrix has been characterized for several environmental conditions (temperature and Relative Humidity). In a second step, we suggest the methodology to extract the behavior of the woven composite material using the numerical results of the tows and the behavior of matrix. The obtained numerical results are compared to the experiment done on the woven thermoplastic composite at different RH. It allows to expose our future prospects

Identification du comportement quasi statique avec prise en compte des conditions environnementales d'un composite tissé thermoplastique par homogénéisation numérique

International audienceThe character of some thermoplastic matrices can strongly influence the behavior of composites due to their sensitivity to the environmental conditions (temperature and/or hygrometry level). When the technical specifications of a design requires a validation of the structure behavior in wide range of temperature and/or hygrometry level, the experiments for both quasi-static and dynamic loadings become expensive and cumbersome. That can greatly restrict the rapid designs of structural pieces, in particular if only main mechanical characteristics such as rupture strain/stress or energy to be dissipated have only to be found. In order to answer to this problem, this paper is dealing with the identification of the quasi-static behavior of such composite using a homogenization at two scales (one for the yarns and one for the composite): in this case, the experiments are reduced because they only concern the matrix. The first obtained results for the ambient temperature and for two different level of hygrometry lead to promising answer to this problematic. These results also offer the important keys of research outlooks related to a better water distribution inside the composite and the consideration of non-perfect fibers/matrix or yarns/matrix interfaces.La nature de certaines matrices thermoplastiques peut avoir un rôle prépondérant dans le comportement des composites en fonction des conditions environnementales (température et/ou hygrométrie). Lorsque les cahiers des charges de conception requièrent une validation du comportement des pièces sur des plages importantes de température et/ou d’hygrométrie, les campagnes expérimentales de caractérisation en quasi-statique et/ou en dynamique deviennent alors très coûteuses et longues. Cela peut constituer un frein dans le cas de préconceptions rapides et notamment lorsqu’on ne souhaite avoir seulement des grandeurs caractéristiques globales telles que contrainte/déformation à rupture, énergie à dissiper... Afin d’apporter une solution à cette problématique, les travaux proposés dans ce papier s’intéresse à l’identification du comportement en quasi-statique de ces matériaux composites en utilisant une homogénéisation numérique à double échelle (une pour les torons et l’autre pour le composite) : dans ce cas, les campagnes de caractérisation sont allégées puisqu’elles ne concernent que la matrice. Les premiers résultats obtenus à température ambiante et pour deux niveaux d’hygrométrie différents apportent une réponse encourageante à la problématique et ouvrent les perspectives des futurs travaux notamment sur une meilleure prise en compte de la répartition de l’eau au sein du composite ainsi que des interfaces fibres/matrice ou torons/matrice non parfaites

Identification of the quasi-static behavior of a woven composite sentitive to the environmental conditions using numercial homogenization

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Advances in ultrasensitive piezoresistive sensors: from conventional to flexible and stretchable applications

Piezoresistive effect has been a dominant mechanical sensing principle that has been widely employed in a range of sensing applications. This transducing concept still receives great attentions because of the huge demand for developing small, low-cost, and high-performance sensing devices. Many researchers have extensively explored new methods to enhance the piezoresistive effect and to make sensors more and more sensitive. Many interesting phenomena and mechanisms to enhance the sensitivity have been discovered. Numerous review papers on piezoresistive effect were published, however, there is no comprehensive review article that thoroughly analyses methods and approaches to enhance the piezoresistive effect. This paper comprehensively reviews and presents all the advanced enhancement methods ranging from quantum physical effect, new materials, nanoscopic and macroscopic structures, and from conventional to flexible, stretchable and wearable applications. In addition, the paper summarises results recently achieved on applying the above-mentioned innovative sensing enhancement techniques in making extremely sensitive piezoresistive transducers