A quasi-random spanning tree model for the early river network

We consider a model for the formation of a river network in which erosion process plays a role only at the initial stage. Once a global connectivity is achieved, no further evolution takes place. In spite of this, the network reproduces approximately most of the empirical statistical results of natural river network. It is observed that the resulting network is a spanning tree graph and therefore this process could be looked upon as a new algorithm for the generation of spanning tree graphs in which different configurations occur quasi-randomly. A new loop-less percolation model is also defined at an intermediate stage of evolution of the river network.Comment: 10 pages, RevTex, 4 postscript figures, accepted in PR

Impact of wind farms capacity factor and participation in frequency support – reliability analysis

Expanded integration of wind energy implies technical confronts to maintain system reliability. Thus, comprehensive reliability models for wind turbines and related features are required. Composite and precise wind farms (WFs) reliability analysis includes wind turbine generator (WTG) detailed models besides wind speed (WS) probabilistic variations considering wake effects. This paper is considered as an extension to the proposed multi-state duration sampling model to asses WTG reliability integrated with a comprehensive representation for WF. The paper investigates the impacts of two WTG frequency support operation algorithms on capacity factors and first hierarchical level indices. LOEE is evaluated using a novel method to emphasis the chronological coordination between load and WS attitudes. System and load points’ reliability indices are estimated at moderate penetration levels of wind energy using a simplified technique. Results insure the feasibility of the composite WTG reliability model and provide reasonable indicators for WFs integration influence

A Unified treatment of small and large- scale dynamos in helical turbulence

Helical turbulence is thought to provide the key to the generation of large-scale magnetic fields. Turbulence also generically leads to rapidly growing small-scale magnetic fields correlated on the turbulence scales. These two processes are usually studied separately. We give here a unified treatment of both processes, in the case of random fields, incorporating also a simple model non-linear drift. In the process we uncover an interesting plausible saturated state of the small-scale dynamo and a novel analogy between quantum mechanical (QM) tunneling and the generation of large scale fields. The steady state problem of the combined small/large scale dynamo, is mapped to a zero-energy, QM potential problem; but a potential which, for non-zero mean helicity, allows tunneling of bound states. A field generated by the small-scale dynamo, can 'tunnel' to produce large-scale correlations, which in steady state, correspond to a force-free 'mean' field.Comment: 4 pages, 1 figure, Physical Review Letters, in pres

Influence of egg parasitic fungus, Engyodontium aranearum against root knot nematode, Meloidogyne incognita

The indigenous egg parasitic fungal isolates, Engyodontium aranearum was evaluated for its nematicidal potential against root knot nematode, Meloidogyne incognita. The study revealed 53.75 per cent egg parasitization by the fungal isolate. Fungal colonies grew over the eggs and fungal hyphae penetrated the egg shells resulting in rupturing of egg shell layers, enzymatic digestion and empty eggs. The fungal culture filtrate was found to inhibit egg hatching by 83.42 per cent and caused upto 91.36 per cent juvenile mortality. This isolate also reduced the attraction of infective juveniles towards tomato root by 79.29 per cent. It seems to be a first report on the antinemic property of the fungus E. aranearum against root knot nematode, M. incognita and its effect was found comparable with Paecilomyces lilacinus which is known as an efficient nematode egg parasitic fungus