Structure of runoff. rainfall MATHEMATICAL MODEL comprises of separation base flow discharge and determining infiltration, effective rainfall and direct runoff. These processes are calculated by various methods. Instantaneous unit hydro graph which Nash MODEL in its index sample has considered as a conceptual MODEL, applied widely in runoff. Rainfall MODELs. Here, the author produces a conceptual MATHEMATICAL MODEL with some proposed methods for determining separation processes of baseflow infiltration, effective rainfall runoff and direct runoff. Non. Linear MATHEMATICAL optimization is used for calculation of the MODEL's parameters. Performance results of the MODEL prove the superiority of the proposed method over the other common ones. For doing the research, both methods of artificial neural networks and MATHEMATICAL optimization of instataneous unit hydrograph are used, because the artificial neural network only, requires a lot of information and the results may not always be obtainable, but an artificial neural network. MATHEMATICAL optimization combination makes possible a quick convergence and assured results.

This paper is aimed to develope a MATHEMATICAL MODEL for sustainable forest development by strategic landuse planning. Such plans are naturally multi purpose so that multi-criteria optimization is utilized for MODELing. The objective functions are: Maximization of carbon sequestration, net present value of income, stand volume, employment generation and minimization of soil erosion. Lp-norm is used to aggregate the objectives. The MODEL is implemented for Caspian forest in Ramsar. Sensitivity analysis is made by different norms and weights.

The survey of effective factors on rainfall-Runoff relations cause to improve MATHEMATICAL MODELs to analysis that phenomena. For this reason, first of all at 80 experimental plots the correlation matrices among runoff coefficient and some other environmental factors conclude from the topography: plot's length and slop percentage, from the soil: clay, silt, sand all percentage, EC, pH, Strength coefficient, gravel percentage and sum of gravel and litter percentage and from the vegetation cover: canopy and organic matter have been surveyed. In the next step at 77 and after 75 plots two rainfall single events with duration of more than 24h and average intensity of 1.5 mm/h selected and MATHEMATICAL MODEL of accumulated infiltration with relation to plot's length based on regression prepared. After, the prepared MODEL tested by a group of plots with equal condition except length and rainfall depth of 38.2 and 34.8mm. The result is that by increasing the plot's length the accumulated infiltration depth added but the intensity of effectiveness of plot's length on accumulated infiltration depth decrease with increasing length of plot and finally after nearly 22m length the variation of the curve of accumulated infiltration depth with plot's length roughly convert to a linear variation with light gradient.

Existing methods of predicting channel morphology are severely limited by their inability to account for bank erosion and changing channel width through time. In this research work, a physically based quasi two dimensional numerical MODEL of channel evolution that account for channel widening has developed and coded by Visual Fortran 6.5 compiler. Prediction of channel evolution is obtained by solving deterministically each of the governing equations of flow resistance.flow momentum and continuity, sediment transport, bank, stability conservation of sediment mass. The MODEL is applicable to relatively straight and bed streams with cohesive bank materials, and thus covers a wide range of alluvial natural streams.

Variable fill fluid couplings are used in the speed control units. Also, variation in coupling oil volume is used in adapting one size of coupling to a wider range of power transmission applications. Available MODEL for the partially filled fluid couplings, has a good performance for couplings with fixed amount of oil but their performance will be degraded if they are used for the variable fill couplings. In this paper, the current MODEL for partially filled fluid couplings is modified to have better performance for variable fill couplings. For this purpose, the circulation loss calculation is modified and also, the effect of oil temperature variations and blade thickness are included in the MODEL. The effect of these modification on the MODEL performance are investigated in couple of simulations. Comparing the simulation results with the available experimental data shows that the suggested modifications can improve the MODEL performance very well.

Study of permeability of Fibrous Composites is important in several natural and industrial processes in mechanical engineering. In this study, a comprehensive MATHEMATICAL MODEL is presented for calculation of normal permeability of ordered elliptical fibrous media. An innovative scale-analysis technique is employed for determining the normal permeability of elliptical fibrous media. In this technique, the permeability is related to the porosity, elliptical fiber diameters, and tortuosity of the medium. In other word, the normal permeability of the circular fibrous structures, which presented in the literature, is extended to the general case of elliptical fibrous media. The composite material is represented by a “unit cell” which is assumed to be repeated throughout the media. A closed-form relation is obtained for non-dimensional permeability using scale analysis approach. Due to lack of experimental data for permeability of fibrous porous media (composite media), with elliptical cross section, a numerical analysis is also employed. The governing equations are solved numerically in the unit cells using finite volume method. The results obtained by numerical solution are compared with those presented by scale analysis method. The presented relation for normal permeability can suitably cover the case of fibrous media with circular cross section. The results are also compared with those presented in the literature for the case of cylindrical fibers. The developed compact relationships are successfully verified through comparison with the present experimental results and the data reported by others.

This paper is concerned with the MATHEMATICAL MODEL development issues necessary for better prediction of dynamic responses of articulated rotor helicopters. The methodology is laid out based on MATHEMATICAL MODEL development for articulated rotor helicopters, using the theories of aeroelastisity, finite element and the time domain compressible unsteady aerodynamics. The helicopter is represented by a set of coupled nonlinear partial differential equations for the main rotor within nonlinear first order ordinary differential equations representation, describing the dynamics of the rest of the helicopter. The complexity of the formulation imposes the use of numerical solution techniques for dynamic response calculations. The validation is performed by comparing simulated responses to flight test data for a known configuration. The results show improvement in dynamic response prediction of both on-axis and cross-coupled responses of helicopter to pilot inputs.

In this article, a MATHEMATICAL / empirical MODEL for the Paykan engine, together with its variable-venturi carburetor is presented. Subsystems of this MODEL include the air and fuel intake systems, as well as the torque generation subMODEL and other important dynamics. The structure of the MODEL provides facilities for simulating the dynamic behavior of the engine in the dynamometer as well as the road test conditions. In order to show the validity of the MODEL, some results from laboratory experiments are also presented.