CHOKe - A stateless active queue management scheme for approximating fair bandwidth allocation

We investigate the problem of providing a fair bandwidth allocation to each of n ows that share the outgoing link of a congested router. The buer at the outgoing link is a simple FIFO, shared by packets belonging to the n ows. We devise a simple packet dropping scheme, called CHOKe, that discriminates against the ows which submit more packets/sec than is allowed by their fair share. By doing this, the scheme aims to approximate the fair queueing policy. Since it is stateless and easy to implement, CHOKe controls unresponsive or misbehaving ows with a minimum overhead. 1 Introduction The Internet provides a connectionless, best eort, end-to-end packet service using the IP protocol. It depends on congestion avoidance mechanisms implemented in the transport layer protocols, like TCP, to provide good service under heavy load. However, a lot of TCP implementations do not include the congestion avoidance mechanism either deliberately or by accident. Moreover, there are a growi..

Optimization of acid catalyzed esterification and mixed metal oxide catalyzed transesterification for biodiesel production from Moringa oleifera oil

Moringa oleifera oil (MOO), a second-generation lipid feedstock that has been reckoned as a promising feedstock for biodiesel production in recent years. In the current study, crude MOO possessing high acid value (80.5 mg of KOH/g) was subjected to two step esterification and transesterification process for biodiesel production and the process was applied with central composite design (CCD) based response surface methodology (RSM). The results showed that H2SO4 concentration of 0.85 vol%, reaction time of 70.20 min, and methanol to oil ratio of 1:1 (vol/vol) significantly decreased the acid value to 3.10 mg of KOH/g of oil. Moreover, copper oxide-calcium oxide (CuO-CaO) nanoparticles were developed and evaluated as a novel heterogeneous base catalyst for synthesizing Moringa oleifera methyl esters (MOME). The synthesized catalyst was scrutinized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX) analysis. Copper oxide (CuO) was perceived to be the dominant phase in the synthesized catalyst. Highest MOME conversion of 95.24% was achieved using 4 wt% CuO-CaO loading, 0.3:1 (vol/vol) methanol to oil ratio and 150 min reaction time as the optimal process conditions

Valorization of walnut shell ash as a catalyst for biodiesel production

The catalytic activity of the walnut shell ash was investigated in the biodiesel production by the sunflower oil methanolysis. The catalyst was characterized by the TG-DTA, XRD, Hg porosimetry, Ny physisorption, SEM, and Hammett method. In addition, the effects of the catalyst loading and the methanolto-oil molar ratio on the methyl esters synthesis were tested at the reaction temperature of 60 degrees C. The walnut shell ash provided a very fast reaction and a high FAME content (over 98%). As the reaction occurred in the absence of triacylglycerols mass transfer limitation, the pseudo-first-order model was employed for describing the kinetics of the reaction. The catalyst was successfully reused four times after the regeneration of the catalytic activity by recalcination at 800 degrees C