A mathematical model describing the dynamics  of a  delayed  stage structure prey - predator  system  with  prey  refuge  is  considered.  The  existence,  uniqueness  and bounded- ness  of  the  solution  are  discussed.    All  the  feasibl e  equilibrium  points  are determined.  The   stability  analysis  of  them  are  investigated.  By  employ ing  the time delay as the bifurcation parame...

this paper deals with the problem of optimizing two-stage structure decision making units (dmus) where the activity and the performance of two-stage dmu in one period effect on its efficiency in the next period. to evaluate such systems the effect of activities in one period on ones in the next term must be considered. to do so, we propose a dynamic dea approach to measure the performance of su...

data envelopment analysis (dea) is a method used for measuring the efficiency of decision-making units‎. unlike the standard models‎, ‎which assume decision-making units to be a black box‎, ‎network data envelopment analysis focuses on the internal structure of these units‎. ‎some researchers have developed a two-stage method where all the inputs are entirely used in the first stage‎, ‎producin...

in this paper an efficient three- stage algorithm is developed for software production cost and time estimation. first stage includes a hybrid model composed of cocomo and function points methods to increase estimation accuracy. second stage encompasses paired comparisons matrix of analytical hierarchy process to determine amount of any resources consumed in each step of software production by ...

The Chadegan metamorphic complex is a WNW-ESE- trending antiformal structure located in Sanandaj-Sirjan structural zone, Iran.The inner core of the structure is made of orthogneiss, containing eclogitic lenses. Schists and marbles lie structurally above theorthogneiss and crop out in the external limbs of the antiformal dome. Two main deformational episodes have been documented in theschists an...

This paper presents a two-stage low-noise ultra-wideband amplifier to obtain high and smooth gain in 180nm CMOS Technology. The proposed structure has two common source stages with inductive feedback. First stage is designed about 3GHz frequency and second stage is designed about 8GHz. In simulation, symmetric inductors of TSMC 0.18um CMOS technology in ADS software is used.Simulations results ...