economic and environmental logging is important for sustainable wood production in the caspian forests, north of iran. predetermination of the skid trail network and directional felling is a usual recommended method to reduce logging impact. the aim of this study was evaluation of directional felling and finding factors effective on felling error. totally 135 trees were selected randomly for di...

post-mineralization activities may cause difficulties in the process of ore modeling in porphyry deposits. sungun, nw iran, is one of the porphyry copper deposits, in which dyke intrusions have made ore modeling more complicated than expected. among different kinds of dykes, two types were chosen and the consequent geostatistical analyses were applied on. in this study, simple directional vario...

the efficiency measurement is a subject of great interest. the majority of studies on dea models have been carried out using radial or non-radial approaches regarding the application of dea for the efficiency measurement. this paper, based on the directional distance function, proposes a new generalized hybrid measure of efficiency under generalized returns to scale with the existence of both r...

The design idea to implement multi-subdividing drive system for stepping motor based on FieldProgrammable Gate Array chip was proposed in this paper. On a piece of EPF10K10LC84-15, the system module was accomplished using Very-High-Speed Integrated Circuit Hardware Description Language and graph editor. The simulation results were shown on the platform MAX+plus . This method could control the s...

We prove that a simple finite bipartite cubic non-planar graph contains a clean subdivision of K3.3. Here a subdivision of K3,3 is defined 1o be clean if it can be obtained from K3,3 by subdividing any edge by an even number of vertices. The proof is constructive and gives rise to a polynomial-time algorithm. @ 1998 Elsevier Science B.V. All rights reserved

directional simulation, among techniques for reliability analysis of engineering structures, is well known. in this context, directional simulation in load space, because of the considerable advantages of lower dimension of working space, is of considerable interest. as is expected due to structural resistance variability, the location of the relevant limit state(s) is no longer constant and mu...

high temperatures are often encountered in almost all of the combustion systems, therefore, thermal radiation heat transfer can influence the droplets heat up rate and consequently their life time. in this paper, the effect of thermal radiation heat transfer is investigated for two cases of directional and spherically symmetric illuminations. the flow and temperature fields insdie and outside o...

We examine the effect of subdividing the potential barrier along the reaction coordinate on Kramers’ escape rate for a model potential. Using the known supersymmetric potential approach, we show the existence of an optimal number of subdivisions that maximises the rate.

This article has focused on evaluation and identification of effective parameters in positioning performance with an odometry approach of an omni-directional mobile robot. Although there has been research in this field, but in this paper, a new approach has been proposed for mobile robot in positioning performance. With respect to experimental investigations of different parameters in omni-dire...