New Computational Algorithms for Analyzing the Stability of the Differential Equations System

In this paper we show how to improve the approximate solution of the large Lyapunov equation obtained by an arbitrary method. Moreover, we propose a new method based on refinement process and Weighted Arnoldi algorithm for solving large Lyapunov matrix equation. Finally, some numerical results will be reported to illustrate the efficiency of the proposed method

In regard to Cuccia et al.: impact of hydrogel peri-rectal spacer insertion on prostate gland intra-fraction motion during 1.5�T MR-guided stereotactic body radiotherapy

We read the article entitled "Impact of hydrogel peri-rectal spacer insertion on prostate gland intra-fraction motion during 1.5 T MR-guided stereotactic body radiotherapy" with great interest. In that study, the author reported that there is a statistically significant difference in the rotational antero-posterior shifts between the spacer and the non-spacer groups. Also, there was no statistically significant difference between the groups in terms of translational shifts. However, there are some points about the study. In this letter, we aimed to clarify these points

Wind erosion measurement on fallow lands of Yazd-Ardakan plain, Iran

Wind erosion is a significant problem on 20 million ha of Iran, especially in central plains and coastal areas. Winderosion samplers, meteorological equipments and measurement procedure have been developed over the last twocenturies to measure the particles moving across the field in modes of creep, saltation and suspension. In recentresearch as the first technical measurement in Iran, wind erosion was measured with these advanced procedures. Fielddata was collected from a small (1.9 ha), square, fallow field with nonerodible boundaries. Wind erosionmeasurement equipment containing 14 clusters with samplers at 0.05, 0.10, 0.25, and 0.50 and 1.0m above the soilsurface and a 4× surface creep sampler (0 to 0.02m height by 0.005m wide) was arranged in a circular pattern. Thesampling cluster consisted of an array of five samplers each attached to a pivoting wind vane and each mounted at adifferent height on a central pole. This permitted field erosion data collection regardless of the wind direction andprovided a range of field lengths with a minimum number of sampler locations. A combination equation of power andexponential functions expressed the variation of transition material to a height of 2m. An exponential modeldescribed the horizontal distribution of transported soil in the field. Twelve single events were recorded and analyzedbetween May 2006 and May 2007. Several inherent soil properties such as soil texture, organic matter and calciumcarbonate content affect the erodibility of soil and change very slowly in research time. Other properties, such assurface roughness and aggregate crust strength are temporal and change rapidly in response to climatic conditions.Total soil mass transported across the fallow field was measured at 220.93 kg/m per year and soil loss at 1.356 kg/m2(13.56 ton/ha) per year

Stability Analysis of Distributed Order Fractional Differential Equations

We analyze the stability of three classes of distributed order fractional differential equations (DOFDEs) with respect to the nonnegative density function. In this sense, we discover a robust stability condition for these systems based on characteristic function and new inertia concept of a matrix with respect to the density function. Moreover, we check the stability of a distributed order fractional WINDMI system to illustrate the validity of proposed procedure

Analytic study on linear systems of distributed order fractional differential equations

In this paper we introduce the distributed order fractional  differential equations (DOFDE) with respect to the nonnegative density function. We generalize the inertia and characteristics polynomial  concepts of pair $(A,B)$ with respect to the nonnegative density function. We also give generalization of the invariant factors of a matrix and some inertia theorems for analyzing the stability of the DOFDE systems

Effects of various super absorbent concentrations on runoff volume in slopes and various intensity of simulated rainfall in Shahrekord plain

Abstract In order to study the effect of super absorbent on runoff volume in slopes and various intensity of rainfall research was accomplish according to split – factorial blocks method with main treatment and two accessory treatments in three replicate . the main treatment consist of three dominant slopes (10 , 20 , 30 percent ) and accessory treatments consist of five levels of substance super absorbent ( instance , 20 , 40 , 60 , 80 kg/ha ) and three levels of various rainfall intensity (25, 30,40 mm/hr). the rain simulator set was used and the rainfall duration intervals was 30 minutes. To establish hydraulic pressure complementary water volume added to reservoir tank in each 5 minutes. Then runoff was gathered to measure output runoff volume. Finally statistical analysis was done on the collected data. Results shows that substance super absorbent treatments of various rainfall intensity in comparison with control plate has significant effect in decrease of output runoff volume to 5 level percent. Keywords: Soil erosion;, Super absorbent; Rain simulation; Volume runoff; Slop

Vector-based model of elastic bonds for DEM simulation of solids

A new model for computer simulation of solids, composed of bonded rigid body particles, is proposed. Vectors rigidly connected with particles are used for description of deformation of a single bond. The expression for potential energy of the bond and corresponding expressions for forces and moments are proposed. Formulas, connecting parameters of the model with longitudinal, shear, bending and torsional stiffnesses of the bond, are derived. It is shown that the model allows to describe any values of the bond stiffnesses exactly. Two different calibration procedures depending on bond length/thickness ratio are proposed. It is shown that parameters of model can be chosen so that under small deformations the bond is equivalent to either Bernoulli-Euler rod or Timoshenko rod or short cylinder connecting particles. Simple expressions, connecting parameters of V-model with geometrical and mechanical characteristics of the bond, are derived. Computer simulation of dynamical buckling of the straight discrete rod and half-spherical shell is carried out.Comment: 11 pages, 6 figure