In this study, we investigate the stress-strain curves of reactive powder concrete (RPC) at high strain rates by using SHPB test, the Burgers’ mechanics model and secant-moduli method. The RPC composites are examined at the age of 10 days containing RPC mortar as the matrix, and three volume concentrations, 1%, 2% and 3%, of steel fiber as the inclusion respectively. Strain rates including 1×10...

BACKGROUND Two-dimensional speckle tracking provides valuable information for regional wall motion abnormalities. The purpose of this study was to determine the diagnostic value of left ventricular longitudinal strain and torsion to diagnose coronary artery disease during dobutamine stress echocardiography. METHODS We studied 100 patients (mean age 60.8 ± 10.7 years, 72 male) with known or su...

The purpose of this paper is to take an entirely geometrical path to determine the evolutionary properties of ecological systems subject to trade-offs. In particular we classify evolutionary singularities in a geometrical fashion. To achieve this, we study trade-off and invasion plots (TIPs) which show graphically the outcome of evolution from the relationship between three curves. The first in...

in this paper, we give some characterizations for legendre spherical, legendre normal and legendre rectifying curves in the 3-dimensional sasakian space. furthermore, we show that legendre spherical curves are also legendre normal curves. in particular, we prove that the inverse of curvature of a legendre rectifying curve is a non-constant linear function of the arclength parameter.

In order to study the dynamic meshing characteristics of the elliptic cylinder gear and obtain the meshing error of the gear transmission system, the two-dimensional static contact analysis of the gear tooth surface is carried out by using ANSYS software, and the key parts of the contact area of the tooth surface are determined. Then, the dynamic meshing model of the elliptic cylinder gear is e...

This study was conducted to compare some nonlinear functions to describe the broiler growth curve of the Cobb500 strain. A flock of fifty one-day-old chicks were randomly selected from a henhouse of 2500 chicks. Our goal was to establish a growth curve using weighting data using mathematical solutions of time-dependent differential functions. In total, six equations were subjected to a statisti...

The material properties of OFHC copper film was investigated with the High-Speed Material Micro Testing Machine (HSMMTM) at the high strain rates. The rate-dependent stress-strain curves from the experiment and the Johnson−Cook curve fitting showed large discrepancies as the plastic strain increases since the constitutive model implies no rate-dependent strain hardening effect. A new constituti...

poly vinyl alcohol/chitosan nanofibrous mat were prepared by electrospinning method with suitable pore sizes as potential matrices for soft tissue engineering. the designed scaffolds by electrospinning method evaluated by differentanalyses such morphological, mechanical, and cellular analysis.microscopic results showed diameters of poly vinyl alcohol/chitosan nanofibers were approximately 150 n...