The article addresses the results of effective water losses prevention in public water supply systems, focusing on procedures for monitoring hidden leaks as the main part of losses and as the first step to control and...The article addresses the results of effective water losses prevention in public water supply systems, focusing on procedures for monitoring hidden leaks as the main part of losses and as the first step to control and prevent them. The described methodology has been applied based on a cross-border cooperation between twin capital cities Vienna and Bratislava in the Central Europe Region within the project deWaloP （Developing Water Loss Prevention） and adopted in Bratislava Water Company （BVS） in the Slovak Republic. The paper provides a complex of simple and easily available practices for analyses of water distribution measurements bringing essential information as to the necessity to use advanced procedures to actively reduce leakage. These practices involve minimum night flows analyses, hydrodynamic pressures analyses, pinpointing of water leakages by working with valves in the water network, the methodology of setting alarm limits for measured data, as well as use of advanced practices to obtain missing topologic data. As the water infrastructure in former socialistic countries are in bad technical condition and the lack of pertinent operational data is a significant obstacle to the application of a more sophisticated methodology based on GIS and other information systems, the procedures focus on using the most simple way to evaluate and control water losses. Finally, the introduction of described methodology in Bratislava Water Company after many years of unsuccessful effort even with expensive sophisticated leakage equipment brought positive outputs and the graph line of water losses level is finally going down. The use of expensive multi-correlating equipment together with human resources on the basis of implementing the above described leakage monitoring will subsequently become more effective, as it shall pinpoint major leakages, disclosure and removal of that shall significantly contribute to the effective reduction of water losses.展开更多
The changes of free solution amount, fluidity and the time-depended fluidity loss of cement paste were examined by varying the water-cement ratio and the dosages of superplasticizer. The distribution of solution and f...The changes of free solution amount, fluidity and the time-depended fluidity loss of cement paste were examined by varying the water-cement ratio and the dosages of superplasticizer. The distribution of solution and flocculation microstructure in flesh cement paste was observed with optical microscope. The change of free solution amount and its effect on the fluidity and bleeding of cement paste was studied. The results show that the adsorbed solution amount has a great influence on the com- patibility of cement-superplasticizer system, including the bleeding degree, the fluidity and the time-depended fluidity loss of cement paste. Superplasticizer increases the fluidity of cement paste by destroying the flocculated cement particle structure and increasing the amount of adsorbed solution. Polycarboxylate superplasticizer shows higher ability of adsorption than naphtha- lene superplasticizer. Over dosage of superplasticizer is not the primary cause of bleeding. The principle reason of bleeding is the high water-cement ratio and the insufficient enhancing ability of water adsorption of superplasticizer.展开更多
文摘The article addresses the results of effective water losses prevention in public water supply systems, focusing on procedures for monitoring hidden leaks as the main part of losses and as the first step to control and prevent them. The described methodology has been applied based on a cross-border cooperation between twin capital cities Vienna and Bratislava in the Central Europe Region within the project deWaloP （Developing Water Loss Prevention） and adopted in Bratislava Water Company （BVS） in the Slovak Republic. The paper provides a complex of simple and easily available practices for analyses of water distribution measurements bringing essential information as to the necessity to use advanced procedures to actively reduce leakage. These practices involve minimum night flows analyses, hydrodynamic pressures analyses, pinpointing of water leakages by working with valves in the water network, the methodology of setting alarm limits for measured data, as well as use of advanced practices to obtain missing topologic data. As the water infrastructure in former socialistic countries are in bad technical condition and the lack of pertinent operational data is a significant obstacle to the application of a more sophisticated methodology based on GIS and other information systems, the procedures focus on using the most simple way to evaluate and control water losses. Finally, the introduction of described methodology in Bratislava Water Company after many years of unsuccessful effort even with expensive sophisticated leakage equipment brought positive outputs and the graph line of water losses level is finally going down. The use of expensive multi-correlating equipment together with human resources on the basis of implementing the above described leakage monitoring will subsequently become more effective, as it shall pinpoint major leakages, disclosure and removal of that shall significantly contribute to the effective reduction of water losses.
基金supported by the National Natural Science Foundation of China (Grant No.50772053)
文摘The changes of free solution amount, fluidity and the time-depended fluidity loss of cement paste were examined by varying the water-cement ratio and the dosages of superplasticizer. The distribution of solution and flocculation microstructure in flesh cement paste was observed with optical microscope. The change of free solution amount and its effect on the fluidity and bleeding of cement paste was studied. The results show that the adsorbed solution amount has a great influence on the com- patibility of cement-superplasticizer system, including the bleeding degree, the fluidity and the time-depended fluidity loss of cement paste. Superplasticizer increases the fluidity of cement paste by destroying the flocculated cement particle structure and increasing the amount of adsorbed solution. Polycarboxylate superplasticizer shows higher ability of adsorption than naphtha- lene superplasticizer. Over dosage of superplasticizer is not the primary cause of bleeding. The principle reason of bleeding is the high water-cement ratio and the insufficient enhancing ability of water adsorption of superplasticizer.
