1. Introduction Operational control of any water distribution network requires that a reliable picture of the present operating state of the system is available. This state is uniquely determined by nodal pressures which, in turn, determine flows through network elements and indicate the amount of water in storage reservoirs. The state vector of pressures needs, however, to be interpreted in th...

This study is descriptive - cross sectional and  during  the 8 months from  winter of 2012 to spring and summer 2013 was performed . In this study at first, with preparation and organization the questionnaire, information about  usage, type and functionality of household treatment systems were collected. Then from 20 Household water treatment ،after water treatment, the samples were taken. samp...

In this study we propose that relationship specific investments reduce the likelihood of relationship dissolution. These types of investments increase switching costs and thereby create barriers towards exiting. Additionally, high levels of relationship specific investments enhance partners' ability and willingness to resort to voice when defections and conflicts arise, and hence postpone exit....

aquatic plants have a major influence upon other aquatic organisms, by altering both water chemistry and spatial structure of the habitat in shallow water bodies. some of them, such as stratiotes aloides l., may suppress algal growth. but how aquatic plants would ultimately influence the heterotrophic community and the aquatic ecosystem as a whole is far from clear. our microcosm-based study de...