Technical Performance Indicators for Small-sized Water Supply Networks - Case Study in Dong Van City, Vietnam

Wasser ist die Basis des Lebens sowie der Existenz und der Schlüssel zur nachhaltigen Entwicklung. Die Generalversammlung der Vereinten Nationen hat das Menschenrecht auf Wasser und sanitäre Einrichtungen anerkannt und bestätigt, dass sauberes Trinkwasser und sanitäre Einrichtungen für die Verwirklichung aller Menschenrechte unerlässlich sind. Tatsächlich verwenden jedoch immer noch 663 Millionen Menschen auf der ganzen Welt nicht verbesserte Trinkwasserquellen wie ungeschützte Brunnen, Quellen und Oberflächenwasser verwenden. Nahezu alle diese Menschen leben in Entwicklungsländern wie Asien oder Afrika. Paradoxerweise weisen diese Länder auch die weltweit höchste Wasserverschwendungsrate auf. Die Weltbank schätzt, dass rund 30% des Wassers, das in Wasserversorgungssystemen verteilt wird, was 45 Millionen Kubikmetern Wasser entspricht, täglich durch Leckagen in Wasserverteilungsnetzen verloren geht. Diese Wassermenge würde ausreichen, um etwa 200 Millionen Menschen zu versorgen. Außerdem werden fast 30 Millionen Kubikmeter Wasser täglich an Kunden ausgeliefert, aber aufgrund von Ungenauigkeiten bei der Messung, Diebstahl, Rechnungsfehler und Korruption nicht in Rechnung gestellt. In den asiatischen Ländern schätzt die Asian Development Bank, dass die nicht Einnahmen generierende Wassermenge (Non-revenue Water) etwa 29 Mrd. m³/Jahr beträgt, was 9 Mrd. USD pro Jahr entspricht. Wenn das Wasservolumen der physischen Verluste auf die Hälfte des derzeitigen Niveaus reduziert wird, reicht dieses Volumen aus, um 150 Millionen Menschen zu versorgen. Es gibt viele Gründe für dieses Problem in Entwicklungsländern, aber die Ineffizienz des Managements von Wasserversorgungssystemen (WSS) ist einer der Hauptgründe. WSS fehlen in diesen Ländern häufig Methoden und Werkzeuge zur Bewertung der Leistung des Betriebs und der Verwaltung sowie zur Verbesserung. Verschiedene Agenturen und Organisationen weltweit haben detaillierte Leistungsbewertungsrahmen aus verschiedenen Indikatoren entwickelt, um alle Aspekte des WSS umfassend abzudecken. Diese Systeme scheinen jedoch nur für WSS in Industrieländern geeignet zu sein, da viele Faktoren bezüglich der Wasserversorgungsbedingungen in Entwicklungsländern nicht erwähnt wurden. In Entwicklungsländern beispielsweise liefern WSS aufgrund begrenzter verfügbarer Bedingungen (z. B. Wasserknappheit und / oder Infrastrukturbeschränkungen) häufig einige Stunden pro Tag Wasser, abhängig von verfügbaren Quellen und der Nachfrage der Kunden, was zu privaten Speichertanks und Schwimmerventilen in den Häusern der Kunden führt, um Wasser während des Zeitraums ohne Wasserzufuhr zu speichern. Der nicht kontinuierliche Betrieb verursacht auch viele unerwünschte Folgen, wie z. B. eine Verringerung der Wasserqualität und schädliche Auswirkungen auf die Anlagen. Darüber hinaus ändert das Vorhandensein von privaten Tanks (möglicherweise mit Schwimmerventilen) nicht nur das Verhalten der Hydraulik im Wasserverteilungssystem, sondern hat auch einen negativen Einfluss auf die Wasserqualität und den fehlerhaften Betrieb der Zähler der Kunden. Trotzdem erwähnen fast alle verfügbaren Evaluierungssysteme nicht diese Beziehungen und Wechselwirkungen in ihren Systemen. Vietnam ist ein typisches Beispiel für Entwicklungsländer in Bezug auf schlechtes Management von WSS. Obwohl Vietnam ein wasserreiches Land mit einem durchschnittlichen jährlichen Wasservolumen von fast 9560 m3 pro Einwohner ist, leidet es immer noch an wirtschaftlicher Wasserknappheit. Gemäß den nationalen Zielen der vietnamesischen Regierung wird im Jahr 2025 die städtische Bevölkerung zu 100% mit Trinkwasser aus zentralen Wasserversorgungssystemen versorgt, während die Abdeckung der Wasserversorgung 2009 noch 73% betrug. Insbesondere in kleinen Städten (Bevölkerung zwischen 4000 und unter 50000) erreichte die Abdeckung nur 50%. Laut Dekret Nr. 42/2009/NĐ-CP der vietnamesischen Regierung beträgt die Anzahl der Kleinstädte 633 in insgesamt 805 Städten Vietnams (etwa 80%). Daher wird die Steigerung der Effizienz beim Betrieb und die Verbesserung der WSS in Kleinstädten einer der Schlüsselfaktoren sein, um die nachhaltige Entwicklung des Wasserversorgungssektors zu gewährleisten, insbesondere bei begrenzten oder knappen Wasserversorgungsressourcen. Kleinere WSS (S-WSS), abgesehen von den oben genannten Herausforderungen, haben weitaus größere Schwierigkeiten als mittlere und große Städte wie beispielsweise niedrige Kapital- und Betriebskosten, geringe physische Vermögenswerte, fehlende Kontroll- und Messgeräte sowie fehlende Daten. Dies führt zu erheblichen Schwierigkeiten bei der Verwaltung und dem Betrieb von S-WSS. Viele spezifische Forschungen erwähnten die Probleme der diskontinuierlichen Versorgung. Es gibt jedoch keine Untersuchungen, die sich umfassend mit den Problemen in S-WSS befassen. In Bezug auf das Management von S-WSS in Entwicklungsländern wird diese Studie ein wichtiges Leistungsbewertungssystem und entsprechende Benchmarks für das Management und den Betrieb von S-WSS in Entwicklungsländern entwickeln. Darüber hinaus schlägt die Studie geeignete Methoden vor, um Daten unter den limitierenden Randbedingungen von S-WSS zu sammeln. Die Studie wird in der Dong Van Stadt, Vietnam, als Fallstudie durchgeführt

Endommagement en surface des alliages d'aluminium en mise en forme à froid

The thesis investigates the mechanisms of galling of aluminum alloys on tools during cold forming. First, an experimental methodology using the test bench UST is proposed. It enables the simulation in the laboratory of the conditions of contact similar to those encountered in industries. A series of trials is performed, testing the material in various conditions of contact pressures, sliding speeds and of lubrication. A link between the contact conditions on the one hand and mass transfer on the other hand tools is established and a mechanism of occurrence of adhesion of aluminum on cold forging tools is proposed. In a second step four damage and failure models are presented and their abilities to predict the onset of galling of aluminum are discussed. A set of finite element simulations is performed and compared to experimental results in order to quantify the influence of contact conditions on evolution of damage encountered in the vicinity of the specimen surface. The results show that a single coefficient of friction is not sufficient to model the severity of the tribosystem. A multi-scale approach is then proposed to simulate the effect of the roughness of the tools on the first step of material transfer. Many prospects are also presented to improve the understanding of the phenomena of bonding and numerical modeling of these phenomena.La thèse étudie les mécanismes de collage des alliages d’aluminium sur les outils lors de leur mise en forme. Dans un premier temps une méthodologie expérimentale utilisant le banc d’essai USTest proposée. Elle permet de travailler en laboratoire en respectant des conditions de contact proches de celles rencontrées en industries. Une campagne d’essais est réalisée, sollicitant le matériau sous diverses conditions de pression de contact, de vitesse de glissement et de lubrification. Les analyses métallurgiques et mécaniques de cette campagne permettent d’établir un lien entre les conditions de contact d’une part et le transfert de matière sur les outils d’autre part. Un mécanisme d’apparition du collage de l’aluminium sur les outils en forge à froid est proposé. Dans un second temps l’aptitude à prédire l’apparition du collage aux outils des alliages d’aluminium lors de leur mise en forme à froid de quatre modèles d’endommagement et de rupture usuels est étudiée. Un ensemble de simulations numériques est mené pour quantifier l’influence des conditions de contact rencontrées lors des essais UST sur l’état d’endommagement des éprouvettes au voisinage de leur surface. Les résultats montrent que le coefficient de frottement seul n’est pas suffisant pour rendre en compte de la sévérité du tribosystème et qu’une approche multiéchelle est nécessaire pour simuler l’effet de la rugosité des outils sur l’apparition des premiers transferts de matière. De nombreuses perspectives sont également présentées pour améliorer la compréhension des phénomènes de collage et la modélisation numérique de ces phénomènes

Experimental investigation of friction behavior in pre-sliding regime for pneumatic cylinder

Friction always presents in pneumatic cylinders and causes difficulties in controlling position and velocity of pneumatic systems. In order to improve the control performance of the pneumatic systems, it is necessary to fully understand behavior of friction in the pneumatic cylinders. So far, dynamic friction behavior of pneumatic cylinders has been investigated but mainly focused on the friction behavior in sliding regime. In pre-sliding regime, friction behavior has not been investigated. In this paper, experimental investigations of friction behavior of a pneumatic cylinder in pre-sliding regime are made. The friction force is calculated from the equation of motion of the piston using the measured values of pressures in the two cylinder chambers and the piston displacement. The pressures are controlled by using two proportional pressure control valve. The friction force versus piston displacement characteristics are measured and analysed under various operating conditions of the applied force and the pressures. Experimental results show that: i) the piston motion in pre-sliding regime exhibits a nonlinear spring behavior; ii) hysteretic behavior with nonlocal memory is verified; iii) the pressures have influence only on the size of the hysteretic loop. These experimental results can be applied to develop a friction model for pneumatic cylinders

Vers la caractérisation du collage des alliages d'aluminium en mise en forme à froid

Les alliages d'aluminium sont des matériaux qui ont une forte tendance aux collages lors de leur mise en forme : une rupture du film lubrifiant séparant la pièce et l'outil peut avoir des conséquences dramatiques sur l'opération de formage (rayures et fissures en surface de la pièce, encrassement et détérioration des outils, etc.). Les travaux présentés étudient les mécanismes de collage d'un alliage d'aluminium 6082 lors de sa mise en forme à froid. Dans un premier temps, une méthodologie expérimentale utilisant le banc d'essai Upsetting-Sliding Test est proposée. Elle permet simuler en laboratoire des conditions de contact proches de celles rencontrées en industries. Une campagne d'essais est réalisée, sollicitant le matériau sous diverses conditions de pression de contact, de vitesse de glissement et de lubrification. Les analyses métallurgiques et mécaniques de cette campagne permettent d'établir un lien entre les conditions de contact d'une part et le transfert de matière sur les outils d'autre part. Les résultats montrent que l'apparition du collage ne se traduit pas par une augmentation importante du coefficient de frottement. Un mécanisme d'apparition du collage de l'aluminium sur les outils en forge à froid est alors proposé. Dans un second temps, l'aptitude à prédire l'apparition du collage des alliages d'aluminium est étudiée à l'aide de quatre modèles d'endommagement et de rupture usuels. Dans cette approche simplifiée, le film lubrifiant n'est pas modélisé, ni les forces d'adhésions. Un ensemble de simulations numériques est mené pour quantifier l'influence des conditions de contact rencontrées lors des essais UST sur l'état d'endommagement des éprouvettes au voisinage de leur surface. Les résultats montrent que le coefficient de frottement seul n'est pas suffisant pour rendre en compte de la sévérité du contact et qu'une approche multiéchelle est nécessaire pour simuler l'effet de la rugosité des outils sur l'apparition des premiers transferts de matière

Efficacy of Adding Oral Simvastatin to Topical Therapy for Treatment of Psoriasis: The Vietnamese Experience

BACKGROUND: Psoriasis, the prevalence of which ranges from 2% to 3% of the general population, has been recently recognised as not only a chronic inflammatory skin disorder but also an immunometabolic systemic disease. Dyslipidemia is one of the most important comorbidities of psoriasis. Statins, frequently used as anti-hyperlipidemic agents, may be beneficial in the treatment of several autoimmune diseases, including psoriasis, due to their anti-inflammatory and immunomodulatory characteristics. Hence, we hypothesised that using this medication was not only beneficial for reducing hyperlipidemia but also improving psoriatic conditions. AIM: We conducted a study to determine the prevalence of dyslipidemia in psoriatic patients as well as whether the addition of statins (simvastatin prescribed forms) to standard topical antipsoriatic treatment can improve skin lesions in psoriatic patients. METHODS: A group of 128 psoriatic patients and 128 healthy controls who were matched with the patients regarding ethnicity, age, and sex were enrolled, and their lipid concentrations were determined. Furthermore, sixty patients were randomly selected from the former group and divided into two treatment subgroups to evaluate the effect of statins on the severity of psoriasis using the PASI score. RESULTS: We found that the rate of dyslipidemia in the patient group was significantly higher than in the healthy group (53.9% versus 21.9%, p < 0.001), particularly the triglyceride concentration (1.86 ± 1.17 versus 1.43 ± 0.79 mg/dL, p < 0.001). Also, the PASI score reduction in the simvastatin-treated subgroup was significantly different from that in the placebo-treated one after eight weeks of therapy (8.63 ± 4.78 versus 5.34 ± 3.59, p < 0.01). CONCLUSION: This study showed that simvastatin might play a role in controlling hyperlipidemia and in turn decrease the PASI score in psoriatic patients

Burden of disease scenarios for 204 countries and territories, 2022–2050: a forecasting analysis for the Global Burden of Disease Study 2021

Background: Future trends in disease burden and drivers of health are of great interest to policy makers and the public at large. This information can be used for policy and long-term health investment, planning, and prioritisation. We have expanded and improved upon previous forecasts produced as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) and provide a reference forecast (the most likely future), and alternative scenarios assessing disease burden trajectories if selected sets of risk factors were eliminated from current levels by 2050. Methods: Using forecasts of major drivers of health such as the Socio-demographic Index (SDI; a composite measure of lag-distributed income per capita, mean years of education, and total fertility under 25 years of age) and the full set of risk factor exposures captured by GBD, we provide cause-specific forecasts of mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) by age and sex from 2022 to 2050 for 204 countries and territories, 21 GBD regions, seven super-regions, and the world. All analyses were done at the cause-specific level so that only risk factors deemed causal by the GBD comparative risk assessment influenced future trajectories of mortality for each disease. Cause-specific mortality was modelled using mixed-effects models with SDI and time as the main covariates, and the combined impact of causal risk factors as an offset in the model. At the all-cause mortality level, we captured unexplained variation by modelling residuals with an autoregressive integrated moving average model with drift attenuation. These all-cause forecasts constrained the cause-specific forecasts at successively deeper levels of the GBD cause hierarchy using cascading mortality models, thus ensuring a robust estimate of cause-specific mortality. For non-fatal measures (eg, low back pain), incidence and prevalence were forecasted from mixed-effects models with SDI as the main covariate, and YLDs were computed from the resulting prevalence forecasts and average disability weights from GBD. Alternative future scenarios were constructed by replacing appropriate reference trajectories for risk factors with hypothetical trajectories of gradual elimination of risk factor exposure from current levels to 2050. The scenarios were constructed from various sets of risk factors: environmental risks (Safer Environment scenario), risks associated with communicable, maternal, neonatal, and nutritional diseases (CMNNs; Improved Childhood Nutrition and Vaccination scenario), risks associated with major non-communicable diseases (NCDs; Improved Behavioural and Metabolic Risks scenario), and the combined effects of these three scenarios. Using the Shared Socioeconomic Pathways climate scenarios SSP2-4.5 as reference and SSP1-1.9 as an optimistic alternative in the Safer Environment scenario, we accounted for climate change impact on health by using the most recent Intergovernmental Panel on Climate Change temperature forecasts and published trajectories of ambient air pollution for the same two scenarios. Life expectancy and healthy life expectancy were computed using standard methods. The forecasting framework includes computing the age-sex-specific future population for each location and separately for each scenario. 95% uncertainty intervals (UIs) for each individual future estimate were derived from the 2·5th and 97·5th percentiles of distributions generated from propagating 500 draws through the multistage computational pipeline. Findings: In the reference scenario forecast, global and super-regional life expectancy increased from 2022 to 2050, but improvement was at a slower pace than in the three decades preceding the COVID-19 pandemic (beginning in 2020). Gains in future life expectancy were forecasted to be greatest in super-regions with comparatively low life expectancies (such as sub-Saharan Africa) compared with super-regions with higher life expectancies (such as the high-income super-region), leading to a trend towards convergence in life expectancy across locations between now and 2050. At the super-region level, forecasted healthy life expectancy patterns were similar to those of life expectancies. Forecasts for the reference scenario found that health will improve in the coming decades, with all-cause age-standardised DALY rates decreasing in every GBD super-region. The total DALY burden measured in counts, however, will increase in every super-region, largely a function of population ageing and growth. We also forecasted that both DALY counts and age-standardised DALY rates will continue to shift from CMNNs to NCDs, with the most pronounced shifts occurring in sub-Saharan Africa (60·1% [95% UI 56·8–63·1] of DALYs were from CMNNs in 2022 compared with 35·8% [31·0–45·0] in 2050) and south Asia (31·7% [29·2–34·1] to 15·5% [13·7–17·5]). This shift is reflected in the leading global causes of DALYs, with the top four causes in 2050 being ischaemic heart disease, stroke, diabetes, and chronic obstructive pulmonary disease, compared with 2022, with ischaemic heart disease, neonatal disorders, stroke, and lower respiratory infections at the top. The global proportion of DALYs due to YLDs likewise increased from 33·8% (27·4–40·3) to 41·1% (33·9–48·1) from 2022 to 2050, demonstrating an important shift in overall disease burden towards morbidity and away from premature death. The largest shift of this kind was forecasted for sub-Saharan Africa, from 20·1% (15·6–25·3) of DALYs due to YLDs in 2022 to 35·6% (26·5–43·0) in 2050. In the assessment of alternative future scenarios, the combined effects of the scenarios (Safer Environment, Improved Childhood Nutrition and Vaccination, and Improved Behavioural and Metabolic Risks scenarios) demonstrated an important decrease in the global burden of DALYs in 2050 of 15·4% (13·5–17·5) compared with the reference scenario, with decreases across super-regions ranging from 10·4% (9·7–11·3) in the high-income super-region to 23·9% (20·7–27·3) in north Africa and the Middle East. The Safer Environment scenario had its largest decrease in sub-Saharan Africa (5·2% [3·5–6·8]), the Improved Behavioural and Metabolic Risks scenario in north Africa and the Middle East (23·2% [20·2–26·5]), and the Improved Nutrition and Vaccination scenario in sub-Saharan Africa (2·0% [–0·6 to 3·6]). Interpretation: Globally, life expectancy and age-standardised disease burden were forecasted to improve between 2022 and 2050, with the majority of the burden continuing to shift from CMNNs to NCDs. That said, continued progress on reducing the CMNN disease burden will be dependent on maintaining investment in and policy emphasis on CMNN disease prevention and treatment. Mostly due to growth and ageing of populations, the number of deaths and DALYs due to all causes combined will generally increase. By constructing alternative future scenarios wherein certain risk exposures are eliminated by 2050, we have shown that opportunities exist to substantially improve health outcomes in the future through concerted efforts to prevent exposure to well established risk factors and to expand access to key health interventions

KINETIC AND EQUILIBRIUM STUDIES ON THE ASSEMBLY OF THE BETA CHAINS OF HUMAN HEMOGLOBIN

In order to study the association-dissociation kinetics of beta chains, analytical molecular sieve measurements were made to determine the stoichiometries and equilibrium constants. At pH 7.0 in phosphate buffer, the assembly of human (beta)CO, (beta)O(,2), deoxy (beta) and cyanomet (beta) chains can be presented as: tetramer-dimer-monomer. In contrast to human hemoglobin, liganded (beta) chains are less dissociated than deoxy (beta) chains. Rapid deoxygenation of (beta)O(,2) leads to increased dissociation of (beta) chains, while rapid CO binding to deoxy (beta) chains leads to increased association. Both light-scattering and absorbance changes are associated with these relaxation processes. Dual-beam light-scattering and absorbance stopped-flow devices were used to determine two dissociation rate constants, k(,42) and k(,21), for both (beta)CO and deoxy (beta) chains. The association rate constants, k(,24) and k(,12), were then obtained from the equilibrium constants. The k(,42) rate constants for (beta)CO and deoxy (beta) were very sensitive to phosphate concentration. An experiment in which deoxy (beta) chains at pH 9.0 were quickly converted to (beta)CO at pH 7.0 and the subsequent light-scattering changes followed, showed that the conformation of the (beta) dimer at pH 9.0 is different from that at pH 7.0. The rate of the conformational change appears to be slow (t(, 1/2)(TURNEQ)3 min). The reaction of p-mercurybenzoate with sulfhydryls on the (beta) chains is complex. The triphasic absorbance changes at 254 nm associated with PMB binding showed that both SH\u27s on the (beta) monomer and one (or 2) on the dimer react rapidly with PMB. The observed light-scattering changes show that (beta)(\u27PMB) chains dissociate in the course of PMB binding. These kinetic results allowed us to suggest a reasonable mechanism for PMB binding to (beta) chains. The self-assemblies of the isolated carp (alpha) and (beta) chains were studied by large-zone gel-filtration. Carp (beta)CO at pH 7.0 was found to be more dissociated than deoxy (beta). At pH 9.0, both (beta)CO and deoxy (beta) chains are tightly associated. Carp (alpha)CO and deoxy (alpha) chains show a D (DBLHARR) 2M stoichiometry, similar to human (alpha)CO at pH 7.0

Damage at the surface of the aluminium alloys cold-forming

La thèse étudie les mécanismes de collage des alliages d’aluminium sur les outils lors de leur mise en forme. Dans un premier temps une méthodologie expérimentale utilisant le banc d’essai USTest proposée. Elle permet de travailler en laboratoire en respectant des conditions de contact proches de celles rencontrées en industries. Une campagne d’essais est réalisée, sollicitant le matériau sous diverses conditions de pression de contact, de vitesse de glissement et de lubrification. Les analyses métallurgiques et mécaniques de cette campagne permettent d’établir un lien entre les conditions de contact d’une part et le transfert de matière sur les outils d’autre part. Un mécanisme d’apparition du collage de l’aluminium sur les outils en forge à froid est proposé. Dans un second temps l’aptitude à prédire l’apparition du collage aux outils des alliages d’aluminium lors de leur mise en forme à froid de quatre modèles d’endommagement et de rupture usuels est étudiée. Un ensemble de simulations numériques est mené pour quantifier l’influence des conditions de contact rencontrées lors des essais UST sur l’état d’endommagement des éprouvettes au voisinage de leur surface. Les résultats montrent que le coefficient de frottement seul n’est pas suffisant pour rendre en compte de la sévérité du tribosystème et qu’une approche multiéchelle est nécessaire pour simuler l’effet de la rugosité des outils sur l’apparition des premiers transferts de matière. De nombreuses perspectives sont également présentées pour améliorer la compréhension des phénomènes de collage et la modélisation numérique de ces phénomènes.The thesis investigates the mechanisms of galling of aluminum alloys on tools during cold forming. First, an experimental methodology using the test bench UST is proposed. It enables the simulation in the laboratory of the conditions of contact similar to those encountered in industries. A series of trials is performed, testing the material in various conditions of contact pressures, sliding speeds and of lubrication. A link between the contact conditions on the one hand and mass transfer on the other hand tools is established and a mechanism of occurrence of adhesion of aluminum on cold forging tools is proposed. In a second step four damage and failure models are presented and their abilities to predict the onset of galling of aluminum are discussed. A set of finite element simulations is performed and compared to experimental results in order to quantify the influence of contact conditions on evolution of damage encountered in the vicinity of the specimen surface. The results show that a single coefficient of friction is not sufficient to model the severity of the tribosystem. A multi-scale approach is then proposed to simulate the effect of the roughness of the tools on the first step of material transfer. Many prospects are also presented to improve the understanding of the phenomena of bonding and numerical modeling of these phenomena

Green Building Certification as a Policy to Promote Green-Building - A Study of Singapore, Taiwan, Australia, UK, US and Lessons for Vietnam

To cope with global environmental crisis and warming, Green Bbuilding (GB) has become a world-wide common trend in construction industries and each country has adopted different policies, programs, strategies to promote GBs in accordance to its owned conditions and context. This paper looks at GB certification from the len of a GB promotion policy, therefore, it concerns about the governmennts’ points of view and actions related to GB cerfitication. The paper summarizes a study of GB certification policies in five countries: Singapore, Taiwan, Australia, UK and US; then overviews current state of GB development in Vietnam, reviews current policy context and analyzes roles of different stakeholders in the market. Through the understanding of the local context, the lesson learnt from the internationally experiences, this paper suggests a policy orientation for excelarating GB development in Vietnam