Charged Particles' Tunneling from Hot-NUT-Kerr-Newman-Kasuya Spacetime

We study the Hawking radiation as charged particles' tunneling across the horizons of the Hot-NUT-Kerr-Newman-Kasuya spacetime by considering the spacetime background as dynamical and incorporating the self-gravitation effect of the emitted particles when the energy conservation, the angular momentum conservation, and the electric charge conservation are taken into account. Our result shows that the tunneling rate is related to the change of Bekenstein-Hawking entropy and the radiant spectrum is not pure thermal, but is consistent with an underlying unitary theory. The emission process is a reversible one, and the information is preserved as a natural result of the first law of black hole thermodynamics.Comment: To appear in: Int. J. Theor. Phy

Mechanical properties and thermal behaviour of two-stage concrete containing palm oil fuel ash

Two-stage concrete (TSC) is a special type of concrete which is made by placing coarse aggregate in a formwork and injecting a grout either by pump or under the gravity force to fill the voids. Over the decades, the application of supplementary cementing materials in conventional concrete has become widespread, and this trend is expected to continue in TSC as well. Palm oil fuel ash (POFA) is one of the ashes which has been recognized as a good pozzolanic material. This paper presents the experimental results on the performance behaviour of POFA in developing physical and mechanical properties of two-stage concrete. Four concrete mixes namely, TSC with 100% OPC as a control, and TSC with 10, 20 and 30% POFA were cast, and the temperature growth due to heat of hydration and heat transfer in the mixes was recorded. It has been found that POFA significantly reduced the temperature rise in two-stage aggregate concrete and delayed the transfer of heat to the mass of concrete. The compressive and tensile strengths, however, increased with the replacement of up to 20% POFA. The results obtained and the observation made in this study suggest that the substitution of OPC by POFA is beneficial, particularly for prepacked mass concrete where thermal cracking due to extreme heat rise is of great importance

The Effect of Web Reinforcement on the Shear Capacity of Brick Aggregate Concrete Beams

Shear capacity of reinforced brick aggregate concrete beams without any web reinforcement and with varying ratio of web reinforcement was studied in this investigation. Deflections of beams and cracks during the progress of loading were recorded. Brick aggregate concrete beams with web reinforcement and two layers of tensile reinforcement were found to have increased cracking shear stress by a considerable amount. Equations for cracking and ultimate shear stresses were suggested within the scope of this study. The experimental values of ultimate shear strength of beams were compared with the values obtained by equations proposed by ACI and other researchers. The equations proposed herein were found to represent the test results better than those of other researchers while remaining on the conservative side. It is hoped that the equations developed herein will provide a rational and basic point of departure from the prevailing concept and will help towards the formulation of a suitable code to provide web reinforcement for brick aggregate concrete beams