No abstract

No abstract

Zinc complexes of new hybrid chiral imine ligands based on a bicyclic skeleton appear to be effective modular catalysts in asymmetric aldol reactions.

A protection zone along water distribution network is one of the proposals to limit the negative effects of potential breakages of buried water pipes, connected with the creation of swallow holes, hollows or depressions [1, 2]. Water flowing out from a leaking pipe can wash out fine soil particles from a solid matrix and move them through soil pores causing suffosion. The phenomena of this kind are dangerous especially in urban areas with developed infrastructure. Empty spaces created incrementally under the soil surface can be hazardous for human health or property-accidents of cars falling in holes created after a water pipe failure are reported several times a year all over the world. The problem still exists because of two reasons. The first is that water supply pipes are usually located along roads, which are used by vehicles at all times, and also where the density of infrastructure is often the highest. The second reason is connected with the fact that water pipes failures and breakages occur randomly during the whole maintenance period of every water supply system in the world [3, 4]. Plenty of methods for leakage detection, evaluating the technical conditions of operating water pipes and risk management in water distribution systems have been reported in the literature in recent years [e.g. 5-11]. Modelling and computer simulations have become common tools for the analysis of pipe failures and leakages [12-17]. Moreover, mathematical approaches, such as fuzzy sets, artificial neural networks or k-nearest neighbours algorithm have been developed lately for predicting