Particles try to converge to the best solution quickly, sometimes too early. PSO’s main drawback is that it is difficult to maintain acceptable levels of population diversity and to balance local and global search, so that suboptimal solutions are prematurely obtained [1]. Some evolutionary techniques maintain population diversity by using certain more or less sophisticated operators or parameters, as the mutation parameter in the case of Genetic Algorithms. Several other mechanisms...

0 Comments Imax submitted 115 days ago

The algorithm previously described in the article “Particle Swarm Optimization” can be considered as the standard PSO algorithm, which is applicable to problems with continue variables and cannot be used directly for discrete problems. Various approaches have been put forward to tackle discrete problems with PSO [1-4]. The approach we propose here for discrete variables...

0 Comments Imax submitted 116 days ago

Particle Swarm Optimization is an evolutionary computation technique that was first developed by Kennedy and Eberhart [1]. Their original idea was to simulate the social behaviour of a flock of birds in their endeavour to reach, when flying through the field (search space), their unknown destination (best fitness function value), e.g. the location of food resources. In PSO, each problem solution is a bird of the flock and is referred to as a particle. Initially a number of particles are randomly generated. Then, particles evolve in terms of their individual and social behaviour and mutually coordinate their movement towards their destination [2]. During the search process each particle...

0 Comments Imax submitted 183 days ago

Many engineering design problems can be cast as optimization problems. The Water Industry is not an exception. Water distribution system design is a wide and open problem in hydraulic engineering that involves the addition of new elements in a system; the rehabilitation or replacement of existing elements; decision-making on operation; reliability and protection of the system; among other actions. Designs are necessary in order to carry out new configurations or to enlarge existing ones to meet new conditions. WaterIng is a software package for water distribution system design and analysis. It offers a multi-objective evolutionary optimization engine based on

1 Comments Imax submitted 206 days ago

The short answer is: for decision making. I was asked this question by a friend some weeks ago and I found myself so much involved with model development that it took me a couple of minutes to give a proper answer of what is the model for and why a water utility needs a model of the water distribution system they are managing. For those people also deeply involved with models development and maintenance it would be also very helpful to ask the same question to themselves. But what kind of decisions can we make and what exactly we obtain from the model? A model by itself cannot make a decision for us but...

1 Comments Imax submitted 258 days ago

EPANET is prepared to run two “separated networks” inside the same model, which is a great advantage in many scenarios but could be a source of trouble when there is just one network where some pipes are disconnected and the user do not realize about it. The INP file of the model presented in this note have a disconnected pipe but will run in EPANET without problems. A user could be happy to realize that EPANET understood that there were two separated “networks” to be analyzed independently but...

0 Comments Imax submitted 263 days ago