The acoustic properties of a compound micro-perforated panel (MPP) absorber array are investigated. The absorber array consists of three parallel-arranged MPP absorbers with different cavity depths. A finite element procedure is used to simulate its acoustic behaviors under normal incidence. Experimental studies are carried out to verify the numerical simulations. Due to different reactance mat...

This paper presents an analysis of the performance of a pancake absorber with a helical heal exchanger for use with point focus solar concentrating collectors. Th e principal difference between this type of absorber and most other concentrating solar collector absorbers is that the intensity of concentrated radiation monotonically increases from the inlet to the outlet of the heat exchanger tub...

This paper presents a wide-angle polarization independent triple-band absorber based on a metamaterial structure for microwave frequency applications. The designed absorber structure is the combination of two resonators (resonator-I and resonator-II). The proposed absorber is ultrathin in thickness (0.012λo at lowest resonance frequency and 0.027λo at highest resonance frequency). The proposed ...

PW cell is used to test radiated electromagnetic field immunity for small equipment up to frequency of several GHz. As the carbon absorbers as a microwave absorber are conventionally used for PW cell, the inside measurement space is limited to small sized EUT. For the tests in this report, we tried to use a pyramid ferrite absorber, which has been developed recently, instead of a carbon absorbe...

When the velocity of fluid flow in a cantilevered pipe is successively increased, the system may become unstable and flutter instability would occur at a critical flow velocity. This paper is concerned with exploring the dynamical stability of a cantilevered fluid-conveying pipe with an additional linear dynamic vibration absorber (DVA) attachment. It is endeavoured to show that the stability o...

The interaction between trace shortwave radiative absorbers and the dynamical circulation is shown to be linearly unstable for horizontally uniform basic states with a vertical gradient in the basic state absorber mixing ratio. Two types of instability are identified, described as the advective mode and the propagating mode. The advective mode is usually unstable when the basic state absorber m...

In this study, solar water heater was investigated using meteorological and geographical data of 129 sites over Turkey. Three different collector types were compared in terms of absorber material (copper, galvanized sheet and selective absorber). Energy requirement for water heating, collector performances, and economical indicators were calculated with formulations using observed data. Results...

On the basis of the continuity equation and the Bernoulli equation in the steady form, a differential equation is developed to evaluate the successive water levels within compartments of an upright perforated wave absorber. Then the initial and boundary conditions are introduced and the differential equation is solved as an initial value problem. Finally the reflection coefficient from the wave...

In the present work the efficiency of a solar parabolic trough has been investigated experimentality. parabolic trough solar collector constitute a proven source of thermal energy for industrial process heat and power genaration. The impact of  using the partially porous media in the absorber on the efficiency of PTC (parabolic trough collector) has been investigated. The porosity of copper foa...