Selvaraj M.D.,Velammal Engineering College |
Mallik R.K.,Indian Institute of Technology Delhi
IEEE Transactions on Vehicular Technology | Year: 2010
Consider a cooperative diversity network that consists of a source, N cooperating relays, and a destination. The relays cooperate with the source through the decode and forward protocol to transmit a data symbol from the source to the destination. In a conventional signal-to-noise ratio based selection combining scheme at the destination, the effect of the source-to-relay links is not accounted for when choosing one link from the set consisting of the source-to-destination and N relay-to-destination links. To overcome this drawback, we modify the conventional scheme by including, in the selection process, a deterministic scale factor that incorporates the effect of the source-to-relay links. For statistically independent links that undergo flat Rayleigh fading, we derive, in closed form, the exact end-to-end symbol error probability (SEP) of this modified scheme, which we call a scaled selection combining scheme for M-ary phase-shift keying constellation. We also give a method of obtaining the optimum scale factor that minimizes the end-to-end SEP. A system designer should select the optimum scale factor to achieve the best performance of the scheme. © 2006 IEEE.
Varatharajan K.,Velammal Engineering College |
Cheralathan M.,SRM University |
Velraj R.,Anna University
Fuel | Year: 2011
Biodiesel offers cleaner combustion over conventional diesel fuel including reduced particulate matter, carbon monoxide and unburned hydrocarbon emissions. However, several studies point to slight increase in NOx emissions (about 10%) for biodiesel fuel compared with conventional diesel fuel. Use of antioxidant additives is one of the most cost-effective ways to mitigate the formation of prompt NOx. In this study, the effect of antioxidant additives on NOx emissions in a jatropha methyl ester fuelled direct injection diesel engine have been investigated experimentally and compared. A survey of literature regarding the causes of biodiesel NOx effect and control strategies is presented. The antioxidant additives L-ascorbic acid, α tocopherol acetate, butylated hydroxytoluene, p-phenylenediamine and ethylenediamine were tested on computerised Kirloskar-make 4 stroke water cooled single cylinder diesel engine of 4.4 kW rated power. Results showed that antioxidants considered in the present study are effective in controlling the NOx emissions of biodiesel fuelled diesel engines. A 0.025%-m concentration of p-phenylenediamine additive was optimal as NOx levels were substantially reduced in the whole load range in comparison with neat biodiesel. However, hydrocarbon and CO emissions were found to have increased by the addition of antioxidants. © 2011 Elsevier Ltd. All rights reserved.
Thiruvengadaravi K.V.,Alagappa Chettiar College of Engineering And Technology |
Nandagopal J.,Velammal Engineering College |
Baskaralingam P.,Alagappa Chettiar College of Engineering And Technology |
Sathya Selva Bala V.,Alagappa Chettiar College of Engineering And Technology |
Sivanesan S.,Alagappa Chettiar College of Engineering And Technology
Fuel | Year: 2012
We report the production of a biodiesel fuel by acid-catalyzed esterification of high free fatty acid (FFA) karanja oil (KO). Pretreated KO was converted to biodiesel by a process of alkaline catalyzed transesterification. Optimum acid-catalyzed esterification was achieved using 1% Sulfated Zirconia (SZ) as a solid acid catalyst with a methanol-to-oil ratio of 9:1, temperature at 60°C and reaction time of 2 h. During this process, FFA were converted into fatty acid methyl esters. The acid value of karanja oil was reduced to 1.3 mg KOH/g from 12.27 mg KOH/g, which confirmed the conversion. Consequently, this pretreatment reduces the overall complexity of the process and reduces the cost of producing biodiesel fuel. © 2012 Elsevier Ltd. All rights reserved.
Malathi G.,Velammal Engineering College |
Shanthi V.,St. Josephs College
Journal of Information Hiding and Multimedia Signal Processing | Year: 2011
Medical diagnosis is the major challenge faced by the medical experts. Highly specialized tools are necessary to assist the experts in diagnosing the diseases. Gestational Diabetes Mellitus is a condition in pregnant women which increases the blood sugar levels. It complicates the pregnancy by affecting the placental growth. The ultrasound screening of placenta in the initial stages of gestation helps to identify the complication induced by GDM on the placental development which accounts for the fetal growth. This work focus on the classification of ultrasound placenta images into normal and abnormal images based on statistical measurements. The ultrasound images are usually low in resolution which may lead to loss of characteristic features of the ultrasound images. The placenta images obtained in an ultrasound examination is stereo mapped to reconstruct the pla- centa structure from the ultrasound images. The dimensionality reduction is done on stereo mapped placenta images using wavelet decomposition. The ultrasound placenta image is segmented using watershed approach to obtain the statistical measurements of the stereo mapped placenta images. Using the statistical measurements, the ultrasound placenta images are then classified as normal and abnormal using Back Propagation neu- ral networks. © 2011 ISSN 2073-4212.
Varatharajan K.,Velammal Engineering College |
Cheralathan M.,SRM University
Fuel Processing Technology | Year: 2013
It is an overwhelming argument that the use of biodiesel instead of petrodiesel causes a reduction in harmful exhaust emissions from engines. A number of studies, however, indicate substantial increases in engine out NO x emissions with biodiesel fuel. Some studies have pointed out that the increased formation of prompt NOx is responsible for biodiesel NOx effect. Treatment of biodiesel with antioxidants is a promising approach because it reduces the formation of hydrocarbon free radicals, which are responsible for prompt NOx production in combustion process. Aromatic amine antioxidants are known as to be efficient inhibitors of free radicals. This study examines the use of p-phenylenediamine derived aromatic amine antioxidants for NOx reduction in a soybean biodiesel fuelled DI diesel engine. The antioxidant additives, N,N′-diphenyl-1,4- phenylenediamine (DPPD) and N-phenyl-1,4-phenylenediamine (NPPD) were tested on a computerised Kirloskar-make 4 stroke water cooled single cylinder diesel engine of 4.4 kW rated power. Results show that significant reduction of NO x could be achieved by the addition of antioxidants but smoke, CO and HC emissions were found to have increased. © 2012 Elsevier B.V.