The K-value (the overall heat transfer coefficient) is an important factor to reflect thermal performance of the covering material in a green house. The measuring process of K -value was burdensome in labors, low accuracy, complicated in dealing with data that is difficult to meet the development of modern agriculture. New testing methods need to be developed, and specially designed for greenho...

Nanocomposite materials, including noble metal nanoparticles embedded in a dielectric host medium, are interesting because of their optical properties linked to surface plasmon resonance phenomena. For studding of nonlinear optical properties and/or energy transfer process, these materials may be excited by ultrashort pulse laser with a temporal width varying from some femtoseconds to some hund...

in this paper, the effect of polypropylene fibers added to concrete on strength and thermal resistance of high strength concrete has been investigated. therefore, five tests have been carried out to reach this goal which it includes; effect of weight percent of polypropylene fibers on mechanical properties of concrete, effect of fiber’s length on the strength of high strength concrete, effect o...

Heat transfer through the gas diffusion layer (GDL) is a key process in the design and operation of a PEM fuel cell. The analysis of this process requires determination of the effective thermal conductivity. This transport property differs significantly in the through-plane and in-plane directions due to the anisotropic micro-structure of the GDL. In the present study, a novel test bed that all...

phenolic resins are synthetic low molecular weight thermoset resins which are polymerized and cured to higher molecular weights by condensation method. these resins have high weathering resistance, high oxidative thermal properties and good chemical resistance. phenolic resins can be cured thermally or by acid curing. the most common method of curing phenolic resin is by thermal curing that tak...

Homogenization of a simultaneous heat and moisture flow in a masonry wall is presented in this paper. The principle objective is to examine an impact of the assumed imperfect hydraulic contact on the resulting homogenized properties. Such a contact is characterized by a certain mismatching resistance allowing us to represent a discontinuous evolution of temperature and moisture fields across th...

The present heating method which uses the cooling system of the internal combustion engine of the vehicle takes a lot of time to heat the interior air. In order to improve the heating process, auxiliary devices are required. The new innovative techniques propose as auxiliary heating device positive temperature coefficient heaters. For a better control of the temperature, the parameters of these...

Material resistance is important since different physicochemical properties can be extracted from it. This work describes a novel resistance measurement method valid for a wide range of resistance values up to 100 GΩ at a low powered, small sized, digitally controlled and wireless communicated device. The analog and digital circuits of the design are described, analysing the main error sources ...

Closed, steady or cyclic thermodynamic systems, which have temperature variations over their boundaries, can represent an extremely large range of plants, devices or natural objects, such as combined heating, cooling and power plants, computers and data centres, and planets. Energy transfer rates can occur across the boundary, which are characterized as heat or work. We focus on the finite time...

This paper aims to calculate the thermal spreading resistance for a hyperellipse on a half space, with uniform heat flux. The effect of shape and aspect ratio on a steady state averaged temperature and the centroid temperature based thermal spreading resistance is studied. The square root of source area and characteristic dimension are assumed as characteristic length scales to obtain the resul...