An approximate numerical mthod is presented for analysis and determination of modal characteristics in straight, pretwisted non-unifom helicopter blades. The analysis considers the coupled flapwise bending (out of plane), chordwise bending (in plane), and torsion vibration of both rotating and non-rotating blades. The proposed method is based on the integral expansion of Green functions (struct...

the pile-raft foundation is a combination of a raft foundation with piles. pile-raft foundation has been widely designed, assuming all structure loads to be transferred to piles without considering contribution of the load taken by contact surface between raft and soil. methods of analysis currently used in practice are based upon relatively conservative assumptions of soil behavior or on the l...

this paper is about discrete sensitivity analysis. a triangular bending element with constant moment and six degrees of freedom is used. the required derivatives for sensitivity analysis are calculated explicitly. these formulations, finite element method and sequential linear programming are utilized to find shape optimization of plate bending structures. the numerical examples, which show the...

Today, Flapping Micro Aerial Vehicles (MAV) are used in many different applications. Reynolds Number for this kind of aerial vehicle is about 104 ~ 105 which shows dominancy of inertial effects in comparison of viscous effects in flow field except adjacent of the solid boundaries. Due to periodic flapping stroke, fluid flow is unsteady. In addition, these creatures have some complexities in kin...

The efficiency and economical performance of sewer systems is an essential issue in urban drainage. The need for sewers to carry sediment has been recognized for many years. One of the main problems in designing sewerage systems is the sediment deposition. Sedimentation in sewers occurs regularly according to the alternating natural flow. The present study investigates the hydraulic characteris...

to control the nonlinear numerical instability, throughout the time evolution of the eulerian form of the nonlinear rotating shallow water equations, it is necessary to add numerical diffusion to the solution. it is clear that, this extra numerical diffusion degrades the accuracy of the numerical solution and should be kept as small as possible. in a conventional approach a hyper-diffusion is u...

representation and modeling of economic uncertainty is addressed by different modeling methods, namely stochastic variables and probabilities, interval analysis, and fuzzy numbers, in particular triple estimates. fo-cusing on discounted cash flow analysis numerical results are presented, comparisons are made between alter-native modeling methods, and characteristics of the methods are discussed.

one priority of planning at the regional level is to recognize the system of residence and particularly its urban system. one of the features of urban system in each area or country is the way of population distribution between the cities of these areas which is called city distribution size. in functional analysis of mazandaran province 41 development indexes of educational, cultural, social, ...

This paper provides an incremental layerwise finite element formulation for the viscoelastic analysis of multilayered pavements.  The constitutive behavior of asphalt concrete is represented by the Prony series. Layerwise finite element has been shown to provide an efficient and accurate tool for the numerical simulation of laminated structures. Most of the previous research on numerical simula...

a class of new methods based on a septic non-polynomial spline function for the numerical solution of problems in calculus of variations is presented. the local truncation errors and the methods of order 2th, 4th, 6th, 8th, 10th, and 12th, are obtained. the inverse of some band matrixes are obtained which are required in proving the convergence analysis of the presented method. convergence anal...