The problem of steady, laminar and incompressible natural convection flow in an OCTAGONALENCLOSURE was studied. In this investigation, two horizontal walls were maintained at a constant hightemperature, two vertical walls were kept at a constant low temperature and all inclined walls wereconsidered adiabatic. The ENCLOSURE was assumed to be filled with a Bousinessq fluid. The studyincludes computations for different Prandtl numbers Pr such as 0.71, 7, 20 and 50 whereas the Rayleighnumber Ra was varied from 103 to 106. The pressure-velocity form of Navier-Stokes equations andenergy equation was used to represent the mass, momentum and energy conservations of the fluidmedium in the ENCLOSURE. The governing equations and boundary conditions were converted todimentionless form and solved numerically by penalty finite element method with discretization bytriangular mesh elements. Flow and heat transfer characteristics were presented in terms of streamlines, isotherms and average Nusselt number Nu. Results showed that the effect of Ra on the convection heattransfer phenomenon inside the ENCLOSURE was significant for all values of Pr studied (0.71-50). It wasalso found that, Pr influence natural convection inside the ENCLOSURE at high Ra (Ra > 104).

Cobalt Oxide/ Zinc Oxide nanocomposite was synthesized by dropwise addition of Co(NO)3.6H2O and Zn(NO3)2.4H2O solutions to KOH solution at different temperatures followed by calcination at 300oC for 4 h. The morphology and structure of nanoparticles and the influence of temperature on particle size were studied using scanning electron microscopy (SEM) and X-Ray Diffraction (XRD). Minimum particle size was obtained before calcination at 70oC. In addition, the spherical, semispherical and flake-shaped nanoparticles were observed at ambient temperature. On the other hand, Co(OH)2 was transformed to Co3O4, ZnO flakes were eliminated, and particle size changed during calcination. Synthesized samples at 50oC and 70oC showed an increase size after calcinations; however, elimination of flakes during calcination caused particle size reduction for synthesized sample at ambient temperature.

There are two main methods in fire modeling: zone models and field models. The conservation of mass and energy in ENCLOSURE is the theoretical base of zone models. The models deal with heat release rate, fire plume, mass flow, smoke movement and gas temperature in fires. Theoretical principles of compartment fire zone modeling are presented and the behavior of fire in ENCLOSUREs is discussed. The conservation laws are presented in control volume form and applied to the behavior of fire in ENCLOSUREs. The governing equations are derived and presented. Some zone models and their field of application in fire modeling are also given.

In this paper, shielding effectiveness (SE) of a perforated ENCLOSURE with imperfectly conducting walls is evaluated. To this end, first, an accurate numerical technique based on method of Moments (MoM) is presented. In this method, lossy metallic walls of the ENCLOSURE are replaced by equivalent electric surface current sources. Then, the impedance boundary condition on the imperfectly conducting surfaces is applied and an electric field integral equation is extracted. At the end, the integral equation is solved numerically by Galerkin method. In addition to the mentioned numerical method, an extremely fast analytical technique based on transmission line model (TLM) is proposed which is able to predict the SE with high level of accuracy over a large frequency bandwidth just in a few seconds. For validation of both methods, other commercial softwares (FEKO and CST) are employed and several ENCLOSUREs with different conductivities are studied. Lossy MoM method shows accurate results for conductivities down to 10S/m, while efficient TLM method proves its accuracy for conductivities down to 250S/m.

After mosques, tombs are the most important buildings of the Islamic period. OCTAGONAL domed Tombs in the Islamic middle ages are more abundant than the early centuries of Islam. The evolution of quadrilateral domed tombs to OCTAGONAL domed tombs occur with the advent of the Seljuk and architecture developments in this period. Kerman province that was regarded as one of the most important centers of the Seljuk rulers, converted to the place of numerous tombs of sufis and elders in this period. It could be noted several examples of OCTAGONAL domed tombs in the Seljuk period that has been prevalent design of the domed tomb in this period. The existence of these buildings is interpreted with reference to local elders and religious figures.

An extended OCTAGONAL ring (EOR) transducer was designed and developed to measure forces inside the compression chamber of a large square baler in different directions. The transducer was calibrated by applying forces in three directions simultaneously and independently. The sensor revealed excellent linearity along with small cross sensitivities. Horizontal and vertical primary sensitivities of the sensor were 1,479.7 and 1387.8 mVkN-1V-1, while horizontal and vertical cross sensitivities were 0.64 and 2.85% of the sensor primary sensitivities, respectively. The sensor was used to measure the forces inside the compression chamber of a large square baler in different directions.