In dual-hop multi-relaying wireless systems, the non-closed form expression in log-normal probability distributions and high varying standard deviations makes it impossible to effectively execute performance analyses of outage probability and bit-error-rate (BER) performance levels; thus, an analysis framework was proposed for use in a composite (Rayleigh plus log-normal) fading channel. Develo...

In this article, the effects of viscous dissipation and inertial force on the velocity and temperature distributions of the mixed convection laminar flow in a vertical channel partly filled with a saturated porous medium have been studied. In this regard, the Brinkman–Forchheimer extended Darcy model was adopted for the fluid flow in the porous region. In addition, three different viscous dissi...

nasoohi n 1 hoorizad m1 torabzadeh tari n 2   1- assistant prof, department of operative dentistry, islamic azad university, dental branch, tehran,iran   2-dentist   corresponding author : nasoohi n: department, no 4, 10th neyestan ave, pasdaran, tehran   tel : 09125392175 email: [email protected]     background and aim: discoloration of dental composites is one of the major reasons of the...

composite pressure vessel cng made of epoxy – carbon material with nonmetal liner is 60% lighter than aluminum vessel under the same conditions. one of the important parameters in the pressure vessels design is their resistance against impact and prevention of explosion. in this paper, the effects of low velocity impact on composite pressure vessel are investigated using fe analysis. the vessel...

to evaluate the ultimate compressive strength of five composite resins after 1 hour, 24 hours, 7 days and 1 month. twenty four cylindrical 4 mm×8mm specimens of each commonly used composite resins in posterior region (nulite-f , z250 , p60, biscore, tetric ceram hb) were prepared. each group of composite resins were divided into four time groups of 1 h, 24 h, 7 days and 1 month. all of specimen...