in this paper, the effect on the strength properties of high strength concrete (hsc) manufactured with silica fume (sf) and ground pumice (gp) is investigated. portland cement was replaced with sf, gp and combination of sf and gp up to 25%. 22 different concrete mixtures with these replacement ratios were produced by using 0.25 water-binder ratio. the ultrasound pulse velocity, compressive, spl...

We have investigated the bimodal distribution of the duration of BATSE gamma-ray bursts (GRBs) by analyzing light curves of 64 ms time resolution. We define the average pulse width of GRBs from the auto-correlation function of GRB profiles. The distribution of the average pulse width of GRBs is bimodal, suggesting that GRBs are composed of long-pulse GRBs and short-pulse GRBs. The average pulse...

As a necessary component, regenerator plays an important role in the refrigeration performance of the pulse tube refrigerator. The objective of this research is to investigate the flow characteristics in a porous regenerator of the pulse tube refrigerators, subjected to oscillating flow. The hydrodynamic and thermal behavior of the regenerator is investigated by considering porous media approac...

In this paper, we report the experimental results of a pulsed flash lamped Nd:YAG laser at wavelength of 1064 nm and Qswitched by Cr4+:YAG solid state saturable absorber. We have obtained the output energy (E) and pulse-width ( p τ ) of this laser for various initial transmissions of this saturable absorber. Furthermore, the effect of reflectivity of the output coupler (R), diameter of the rod ...

We present the procedure for designing a high speed and low power all-optical analog to digital converter (AO-ADC), by integrating InGaAsP semiconductor optical amplifier (SOA) with InP based photonic crystal (PhC) drop filters. The self-phase modulation in the SOA can shift the frequency of the Gaussian input pulse. The two output PhC based drop filters are designed to appropriately code the f...

BACKGROUND The aim of this study was to test the effect of different pulse frequencies and amplitudes during gastric stimulation (GS) on gastric emptying in the rat. METHODS GS was performed in 2 groups of laparotomized rats: healthy control animals, and rats with acute diabetes. The effects of four pulse frequencies (0.5, 1, 10, 20 Hz) and three pulse amplitudes (5, 20, 40 mA) were tested. T...