Improvement of Transmission Control Protocol for High Bandwidth Applications

Transmission control protocol (TCP) is the widely and dominantly used protocol in today’s internet. A very recent implementation of congestion control algorithm is BBR by Google. Bottleneck bandwidth and round-trip time (BBR) is a congestion control algorithm which is created with the aim of increasing throughput and reducing delay. The congestion control protocols mentioned previously try to determine congestion limits by filling router queues. BBR drains the router queues at the bottleneck by sending exactly at the bottleneck link rate. This is done by the BBR through pacing rate which infers the delivery rate of the receiver and uses this as the estimated bottleneck bandwidth. But when the data rate is high, in the startup phase itself pipe becomes full and leads to some degradation in the Access Point of wireless environments by inducing losses specific to this environment. So the current pacing rate is not suitable for producing higher throughputs. Therefore, in the proposed system named R-BBR, this startup gain should be lower than the current startup gain which eventually would reduce pacing rate to reduce queue pressure in the sink node during the startup phase. The startup phase of BBR is modified to solve the problem of pipe full under high data rate. R-BBR has been evaluated over a wide range of wired as well as wireless networks by varying different factors like startup gain, congestion window, and pacing rate. It is inferred that R-BBR performs better than BBR with significant performance improvement.

     

Non-equilibrium Phases Formed in Cu–In–Se–Te System Synthesized by Melt-Quench Method

Non-equilibrium phases formed in melt-quenched Cu In(SexTe1-x)2system, where x = 0.1, 0.2, 0.4, 0.5, 0.6,0.8 and 0.9, have been studied using Rietveld refinement of the crystal structure and Raman spectroscopy. Results of structure refinement have showed that all the samples, except the Cu In(Se0.1Te0.9)2, are heterogeneous. All the observed non-equilibrium phases are quaternary system and are found to have chalcopyrite structure(I"42d), in accordance with the Cu In Te2–Cu In Se2 phase diagram. The lattice constants deduced from the refinement have showed linear variation with Se content. A detailed analysis of the characteristic A1 modes present in the Raman spectrum of individual sample has corroborated the results obtained from the structure analysis. The position of A1 mode of individual phase is found to vary linearly with Se content, which suggests that Cu In(SexTe1-x)2system exhibits single-mode behaviour.     

Production and analysis of bio-diesel from non-edible oils—A review

Bio-diesel has become more attractive recently because of its environmental benefits and it is derived from renewable resources, bio degradable and non-toxic in nature. Several bio-diesel production methods have been developed, among which transesterification using alkali catalyst gives high level of conversion of triglycerides to their corresponding methyl ester in short reaction time. The process of transesterification is affected by the reaction condition, molar ratio of alcohol to oil, type of alcohol, type and amount of catalysts, reaction time and temperature, purity of reactants free fatty acids and water content of oils or fats. In this work, an attempt has been made on review of bio-diesel production, methods of analyzing, bio-diesel standard, resources available, process developed performance in internal combustion engines, teardown analysis of bio-diesel B20 operated vehicle, recommendation for development of bio-fuels, environmental considerations, economic aspects and advantages. The technical tools and process for monitoring the transesterification reaction like TLC, GC, HPLC, GPC, ¹H NMR and NIR have also been summarized in this paper.     

Studies on the effect of weld defect on the fatigue behavior of welded structures

Structural integrity isstated as the science and technology of margin between safety and disaster. Systematic prediction of structural integrity of critical structures such ascombustion chambers,pressure vessels,nuclear reactor components,boilers etc.,ensures the human safety,environmental protection,and the economical considerations.The present work aims at prediction of fatigue behaviour of symmetric structures like pressure vessels in the presence of common welding defects such as lack of fusion( LOF),lack of penetration( LOP) and porosity.A ring type specimen which replicates the stress pattern in thepressure vessel is considered for the study of severity of weld imperfections. Initial dimensions of weld defects are arrived by performing NDT inspection.Crack growth analysis is carried out to determine the remaining life of the welded joint with defects.     

Update: An Efficient Synthesis of Poly(ethylene glycol)‐Supported Iron(II) Porphyrin Using a Click Reaction and its Application for the Catalytic Olefination of Aldehydes

The facile synthesis of polyethylene glycol (PEG)‐immobilized iron(II) porphyrin using a copper‐catalyzed azide‐alkyne [3+2] cycloaddition “click” reaction is reported. The prepared complex 5 (PEG‐C₅₁H₃₉FeN₇O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG‐supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss.     

Experimental investigation of PV based modified SEPIC converter fed hybrid electric vehicle (PV-HEV)

This paper presents a high gain modified three-port dual boost single-ended primary-inductor converter (SEPIC) converter operated hybrid photovoltaic (PV)/battery electric vehicle to improve the power transfer capability and efficiency of the power conversion stage. The proposed three-port dual boost high gain SEPIC converter accepts wide voltage range of input then the conventional single stage SEPIC converter. The three-winding high frequency coupling transformer integrates the two input sources and step-up the input voltage. The theoretical and experimental analyses are presented to validate the performance of the proposed modified SEPIC converter in boosting the wide range of input voltage. A 6 kW, 12 to 600 V of experimental model has been developed and tested. The efficiency obtained from the designed model is around 94.11%.