16 research outputs found
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 SchlĂŒssel zur nachhaltigen Entwicklung. Die Generalversammlung der Vereinten Nationen hat das Menschenrecht auf Wasser und sanitĂ€re Einrichtungen anerkannt und bestĂ€tigt, dass sauberes Trinkwasser und sanitĂ€re Einrichtungen fĂŒr die Verwirklichung aller Menschenrechte unerlĂ€sslich sind. TatsĂ€chlich verwenden jedoch immer noch 663 Millionen Menschen auf der ganzen Welt nicht verbesserte Trinkwasserquellen wie ungeschĂŒtzte Brunnen, Quellen und OberflĂ€chenwasser verwenden. Nahezu alle diese Menschen leben in EntwicklungslĂ€ndern wie Asien oder Afrika. Paradoxerweise weisen diese LĂ€nder auch die weltweit höchste Wasserverschwendungsrate auf. Die Weltbank schĂ€tzt, dass rund 30% des Wassers, das in Wasserversorgungssystemen verteilt wird, was 45 Millionen Kubikmetern Wasser entspricht, tĂ€glich durch Leckagen in Wasserverteilungsnetzen verloren geht. Diese Wassermenge wĂŒrde ausreichen, um etwa 200 Millionen Menschen zu versorgen. AuĂerdem werden fast 30 Millionen Kubikmeter Wasser tĂ€glich an Kunden ausgeliefert, aber aufgrund von Ungenauigkeiten bei der Messung, Diebstahl, Rechnungsfehler und Korruption nicht in Rechnung gestellt. In den asiatischen LĂ€ndern schĂ€tzt die Asian Development Bank, dass die nicht Einnahmen generierende Wassermenge (Non-revenue Water) etwa 29 Mrd. mÂł/Jahr betrĂ€gt, was 9 Mrd. USD pro Jahr entspricht. Wenn das Wasservolumen der physischen Verluste auf die HĂ€lfte des derzeitigen Niveaus reduziert wird, reicht dieses Volumen aus, um 150 Millionen Menschen zu versorgen.
Es gibt viele GrĂŒnde fĂŒr dieses Problem in EntwicklungslĂ€ndern, aber die Ineffizienz des Managements von Wasserversorgungssystemen (WSS) ist einer der HauptgrĂŒnde. WSS fehlen in diesen LĂ€ndern hĂ€ufig 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 fĂŒr WSS in IndustrielĂ€ndern geeignet zu sein, da viele Faktoren bezĂŒglich der Wasserversorgungsbedingungen in EntwicklungslĂ€ndern nicht erwĂ€hnt wurden.
In EntwicklungslĂ€ndern beispielsweise liefern WSS aufgrund begrenzter verfĂŒgbarer Bedingungen (z. B. Wasserknappheit und / oder InfrastrukturbeschrĂ€nkungen) hĂ€ufig einige Stunden pro Tag Wasser, abhĂ€ngig von verfĂŒgbaren Quellen und der Nachfrage der Kunden, was zu privaten Speichertanks und Schwimmerventilen in den HĂ€usern der Kunden fĂŒhrt, um Wasser wĂ€hrend des Zeitraums ohne Wasserzufuhr zu speichern. Der nicht kontinuierliche Betrieb verursacht auch viele unerwĂŒnschte Folgen, wie z. B. eine Verringerung der WasserqualitĂ€t und schĂ€dliche Auswirkungen auf die Anlagen. DarĂŒber hinaus Ă€ndert das Vorhandensein von privaten Tanks (möglicherweise mit Schwimmerventilen) nicht nur das Verhalten der Hydraulik im Wasserverteilungssystem, sondern hat auch einen negativen Einfluss auf die WasserqualitĂ€t und den fehlerhaften Betrieb der ZĂ€hler der Kunden. Trotzdem erwĂ€hnen fast alle verfĂŒgbaren Evaluierungssysteme nicht diese Beziehungen und Wechselwirkungen in ihren Systemen.
Vietnam ist ein typisches Beispiel fĂŒr EntwicklungslĂ€nder in Bezug auf schlechtes Management von WSS. Obwohl Vietnam ein wasserreiches Land mit einem durchschnittlichen jĂ€hrlichen Wasservolumen von fast 9560 m3 pro Einwohner ist, leidet es immer noch an wirtschaftlicher Wasserknappheit. GemÀà den nationalen Zielen der vietnamesischen Regierung wird im Jahr 2025 die stĂ€dtische Bevölkerung zu 100% mit Trinkwasser aus zentralen Wasserversorgungssystemen versorgt, wĂ€hrend die Abdeckung der Wasserversorgung 2009 noch 73% betrug. Insbesondere in kleinen StĂ€dten (Bevölkerung zwischen 4000 und unter 50000) erreichte die Abdeckung nur 50%. Laut Dekret Nr. 42/2009/NÄ-CP der vietnamesischen Regierung betrĂ€gt die Anzahl der KleinstĂ€dte 633 in insgesamt 805 StĂ€dten Vietnams (etwa 80%). Daher wird die Steigerung der Effizienz beim Betrieb und die Verbesserung der WSS in KleinstĂ€dten einer der SchlĂŒsselfaktoren sein, um die nachhaltige Entwicklung des Wasserversorgungssektors zu gewĂ€hrleisten, insbesondere bei begrenzten oder knappen Wasserversorgungsressourcen.
Kleinere WSS (S-WSS), abgesehen von den oben genannten Herausforderungen, haben weitaus gröĂere Schwierigkeiten als mittlere und groĂe StĂ€dte wie beispielsweise niedrige Kapital- und Betriebskosten, geringe physische Vermögenswerte, fehlende Kontroll- und MessgerĂ€te sowie fehlende Daten. Dies fĂŒhrt zu erheblichen Schwierigkeiten bei der Verwaltung und dem Betrieb von S-WSS. Viele spezifische Forschungen erwĂ€hnten 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 EntwicklungslĂ€ndern wird diese Studie ein wichtiges Leistungsbewertungssystem und entsprechende Benchmarks fĂŒr das Management und den Betrieb von S-WSS in EntwicklungslĂ€ndern entwickeln. DarĂŒber hinaus schlĂ€gt 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 durchgefĂŒhrt
Endommagement en surface des alliages d'aluminium en mise en forme Ă 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 thĂšse Ă©tudie les mĂ©canismes de collage des alliages dâaluminium sur les outils lors de leur mise en forme. Dans un premier temps une mĂ©thodologie expĂ©rimentale utilisant le banc dâessai USTest proposĂ©e. Elle permet de travailler en laboratoire en respectant des conditions de contact proches de celles rencontrĂ©es en industries. Une campagne dâessais est rĂ©alisĂ©e, sollicitant le matĂ©riau sous diverses conditions de pression de contact, de vitesse de glissement et de lubrification. Les analyses mĂ©tallurgiques et mĂ©caniques de cette campagne permettent dâĂ©tablir un lien entre les conditions de contact dâune part et le transfert de matiĂšre sur les outils dâautre part. Un mĂ©canisme dâapparition du collage de lâaluminium sur les outils en forge Ă froid est proposĂ©. Dans un second temps lâaptitude Ă prĂ©dire lâapparition du collage aux outils des alliages dâaluminium lors de leur mise en forme Ă froid de quatre modĂšles dâendommagement et de rupture usuels est Ă©tudiĂ©e. Un ensemble de simulations numĂ©riques est menĂ© pour quantifier lâinfluence des conditions de contact rencontrĂ©es lors des essais UST sur lâĂ©tat dâendommagement des Ă©prouvettes au voisinage de leur surface. Les rĂ©sultats montrent que le coefficient de frottement seul nâest pas suffisant pour rendre en compte de la sĂ©vĂ©ritĂ© du tribosystĂšme et quâune approche multiĂ©chelle est nĂ©cessaire pour simuler lâeffet de la rugositĂ© des outils sur lâapparition des premiers transferts de matiĂšre. De nombreuses perspectives sont Ă©galement prĂ©sentĂ©es pour amĂ©liorer la comprĂ©hension des phĂ©nomĂšnes de collage et la modĂ©lisation numĂ©rique de ces phĂ©nomĂšnes
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 piÚce et l'outil peut avoir des conséquences dramatiques sur l'opération de formage (rayures et fissures en surface de la piÚce, 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 matiÚre 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 modÚles 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 matiÚre
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 ñ 1.17 versus 1.43 ñ 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 ñ 4.78 versus 5.34 ñ 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
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 thĂšse Ă©tudie les mĂ©canismes de collage des alliages dâaluminium sur les outils lors de leur mise en forme. Dans un premier temps une mĂ©thodologie expĂ©rimentale utilisant le banc dâessai USTest proposĂ©e. Elle permet de travailler en laboratoire en respectant des conditions de contact proches de celles rencontrĂ©es en industries. Une campagne dâessais est rĂ©alisĂ©e, sollicitant le matĂ©riau sous diverses conditions de pression de contact, de vitesse de glissement et de lubrification. Les analyses mĂ©tallurgiques et mĂ©caniques de cette campagne permettent dâĂ©tablir un lien entre les conditions de contact dâune part et le transfert de matiĂšre sur les outils dâautre part. Un mĂ©canisme dâapparition du collage de lâaluminium sur les outils en forge Ă froid est proposĂ©. Dans un second temps lâaptitude Ă prĂ©dire lâapparition du collage aux outils des alliages dâaluminium lors de leur mise en forme Ă froid de quatre modĂšles dâendommagement et de rupture usuels est Ă©tudiĂ©e. Un ensemble de simulations numĂ©riques est menĂ© pour quantifier lâinfluence des conditions de contact rencontrĂ©es lors des essais UST sur lâĂ©tat dâendommagement des Ă©prouvettes au voisinage de leur surface. Les rĂ©sultats montrent que le coefficient de frottement seul nâest pas suffisant pour rendre en compte de la sĂ©vĂ©ritĂ© du tribosystĂšme et quâune approche multiĂ©chelle est nĂ©cessaire pour simuler lâeffet de la rugositĂ© des outils sur lâapparition des premiers transferts de matiĂšre. De nombreuses perspectives sont Ă©galement prĂ©sentĂ©es pour amĂ©liorer la comprĂ©hension des phĂ©nomĂšnes de collage et la modĂ©lisation numĂ©rique de ces phĂ©nomĂšnes.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 governmenntsĂąâŹâą 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
Hâ/LPV active braking control system to prevent rollover of heavy vehicles
International audienceRollover of heavy vehicles is an important road safety problem world-wide. Several active control schemes have been proposed to prevent rollover, such as active steering, active suspension, active anti-roll bars, with the active braking system being the most common method used for heavy vehicles. In this paper, the active braking system is combined with the passive anti-roll bar system (the passive suspension system). The grid-based LPV approach is used to synthesize the Hâ/LPV controller which is self-scheduled by two varying parameters: the forward velocity and the normalized load transfer at the rear axle. The parameter dependent weighting function for the lateral acceleration is used in order to allow for the vehicle performance adaptation to the risk of rollover. Simulation results are performed in the frequency domain, and emphasize the efficiency of the proposed methodology