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Search Results: 1 - 10 of 433 matches for " Venkatesan Thiruvengadam "
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Interspecific hybridization between Cajanus cajan and Cajanus cajanifolius
Venkatesan Thiruvengadam,Arunachalam Muthiah
Crop Breeding and Applied Biotechnology , 2007,
Abstract: Interspecific hybridization between five Canajus cajan genotypes viz., ICPL 87, CORG 9302, CORG 5, TAT 93-47 and AS 46 and the wild species C. cajanifolius was attempted. Successful pod set was observed in direct crosses involvingC. cajan as ovule parent and C. cajanifolius as pollen parent while the reciprocal crosses failed to set pods. The only survivingF1 of ICPL 87 × C. cajanifolius was vigorous in growth and exhibited intermediate leaf and flower morphology with predominanceof C. cajanifolius plant type. Chromosome pairing was rather irregular in the F1 hybrid with loose pairing, univalents,quadrivalents and abnormalities like laggards, stickiness, bridges, precocious separation and non-synchronization of thegenomes. Pollen fertility of the hybrid was low and occurrence of triads was noticed. The partial homology coupled with seedset suggested the possibility of incorporating traits of economic importance such as pest resistance from C. cajanifolius intoC. cajan.
Performance Analysis of the 3GPP-LTE Physical Control Channels
Thiruvengadam SJ,Jalloul LouayMA
EURASIP Journal on Wireless Communications and Networking , 2010,
Abstract: Maximum likelihood-based (ML) receiver structures are derived for the decoding of the downlink control channels in the new long-term evolution (LTE) standard based on multiple-input and multiple-output (MIMO) antennas and orthogonal frequency division multiplexing (OFDM). The performance of the proposed receiver structures for the physical control format indicator channel (PCFICH) and the physical hybrid-ARQ indicator channel (PHICH) is analyzed for various fading-channel models and MIMO schemes including space frequency block codes (SFBC). Analytical expressions for the average probability of error are derived for each of these physical channels. The impact of channel-estimation error on the orthogonality of the spreading codes applied to users in a PHICH group is investigated, and an expression for the signal-to-self interference plus noise ratio is derived for Single Input Multiple Output (SIMO) systems. Finally, a matched filter bound on the probability of error for the PHICH in a multipath fading channel is derived. The analytical results are validated against computer simulations.
Interparticle interactions mediated superspinglass to superferromagnetic transition in Ni-bacterial cellulose aerogel nanocomposites
V. Thiruvengadam,Satish Vitta
Physics , 2015,
Abstract: The interparticle interactions in a magnetic nanocomposite play a dominant role in controlling the phase transitions superparamagnetic to superspinglass to superferromagnetic. These interactions can be tuned by controlling the size and number density of nanoparticles. Aerogel composites, 0.3 Ni-BC and 0.7 Ni-BC, consisting of Ni nanoparticles distributed in bacterial cellulose have been used as model systems to study the effect of interparticle interactions with increasing fraction of Ni in the composite. Contrary to conventional approach, the size of Ni nanoparticles is not controlled and was allowed to form naturally in the bacterial cellulose template. The structural characterization using x-ray diffraction and electron microscopies indicates the presence of only Ni and cellulose with no other phases. The uncontrolled growth of Ni in cellulose matrix results in the formation of nanoparticles with 3 different size distributions - 10 nm particles mainly distributed along the length of fibrils, 50 nm particles present in the intermediate spaces between the fibrils and 100 nm particles present in voids formed by the reticulate structure. At room temperature the composites exhibit a weakly ferromagnetic behavior with a coercivity of 40 Oe which increases to 160 Oe at 10 K. The transition from weakly ferromagnetic state at room temperature to a superferromagnetic state at low temperatures is mediated via a superspinglass state at intermediate temperatures. A temperature dependent microstructural model has been developed combining the structural and magnetic results obtained from the two composite aerogels.
Video Based Vehicle Detection and its Application in Intelligent Transportation Systems  [PDF]
Naveen Chintalacheruvu, Venkatesan Muthukumar
Journal of Transportation Technologies (JTTs) , 2012, DOI: 10.4236/jtts.2012.24033
Abstract: Video based vehicle detection technology is an integral part of Intelligent Transportation System (ITS), due to its non-intrusiveness and comprehensive vehicle behavior data collection capabilities. This paper proposes an efficient video based vehicle detection system based on Harris-Stephen corner detector algorithm. The algorithm was used to develop a stand alone vehicle detection and tracking system that determines vehicle counts and speeds at arterial roadways and freeways. The proposed video based vehicle detection system was developed to eliminate the need of complex calibration, robustness to contrasts variations, and better performance with low resolutions videos. The algorithm performance for accuracy in vehicle counts and speed was evaluated. The performance of the proposed system is equivalent or better compared to a commercial vehicle detection system. Using the developed vehicle detection and tracking system an advance warning intelligent transportation system was designed and implemented to alert commuters in advance of speed reductions and congestions at work zones and special events. The effectiveness of the advance warning system was evaluated and the impact discussed.
Hybrid Control Strategy for Matrix Converter Fed Wind Energy Conversion System  [PDF]
Jamna Ayadathil, Jamuna Venkatesan
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.710259
Abstract: In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence it is necessary to design a system that regulates output parameters, such as voltage and frequency, and thereby provides a constant voltage and frequency output from the wind energy conversion system. Matrix converter is used in the proposed solution as the main power conditioner as a more efficient alternative when compared to traditional back-back converter structure. To control the output voltage, a vector modulation based refined control structure is used. A power tracker is included to maximize the mechanical output power of the turbine. Over current protection and clamp circuit input protection have been introduced to protect the system from over current. It reduces the spikes generated at the output of the converter. The designed system is capable of supplying an output voltage of constant frequency and amplitude within the expected ranges of input during the operation. The matrix converter control using direct modulation method, modified Venturini modulation method and vector modulation method was simulated, the results were compared and it was inferred that vector modulation method was superior to the other two methods. With the proposed technique, voltage transfer ratio and harmonic profile have been improved compared to the other two modulation techniques. The behaviour of the system is corroborated by MATLAB Simulink, and hardware is realized using an FPGA controller. Experimental results are found to be matching with the simulation results.
A SRF-PLL Control Scheme for DVR to Achieve Grid Synchronization and PQ Issues Mitigation in PV Fed Grid Connected System  [PDF]
Saritha Natesan, Jamuna Venkatesan
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.710256
Abstract: This paper presents the Synchronous Reference Frame Theory (SRF) based Phase Locked Loop (PLL) to enhance the performance of Dynamic Voltage Controller (DVR). In a grid connected power conversion system, a critical component is the Phase-Locked Loop (PLL) that generates the grid voltage’s frequency and phase angle for the grid synchronization. For grid voltage control, accurate and fast responding PLLs are required to provide phase angle and frequency measurements of the grid voltage. Therefore, SRF based PLL is presented in this work and it calculates the phase angle accurately and effectively. This paper also presents a novel feedback mechanism for SRF-PLL which uses the estimated frequency and phase to achieve grid control. The fundamental signal of the grid voltage is extracted by low pass filter and a unit value controller to generate a unity sine reference signal for the feedback network. In particular, the performance of the SRF-PLL in the three-phase PV fed grid connected system is analyzed under the different power quality issues such as voltage sag and swell. In addition, a detailed study on synchronous reference frame theory is presented. An appropriate control algorithm for DVR is developed and the validity of the proposed configuration is verified through MATLAB simulation results as well as experimental results under different operating conditions.
A challenging case of gastric outlet obstruction (Bouveret's syndrome): a case report
Mahesh Gajendran, Thiruvengadam Muniraj, Andres Gelrud
Journal of Medical Case Reports , 2011, DOI: 10.1186/1752-1947-5-497
Abstract: An 82-year-old Caucasian woman presented with signs and symptoms of small bowel obstruction. Her laboratory workup showed elevated alkaline phosphatase and amylase levels. Computed tomography of her abdomen revealed pneumobilia, a choledochoduodenal fistula and a gallstone obstructing her distal duodenum. The impacted gallstone could not be extracted endoscopically, so our patient underwent open enterolithotomy successfully. However, the postoperative course was complicated by myocardial infarction, respiratory failure and disseminated intravascular coagulation. She died 22 days after surgery, secondary to cardiopulmonary arrest.This case clearly highlights the considerable morbidity and mortality associated with Bouveret's syndrome.Bouveret's syndrome is defined as a cholecystoduodenal or choledochoduodenal fistula with the passage of a gallstone into the duodenum or pylorus leading to gastric outlet obstruction [1]. There have been very few case reports about this syndrome published in the last 100 years because of its rarity. It is associated with high morbidity and mortality rates. With the availability of computed tomography (CT) scans, earlier diagnosis and better management of these cases are possible. Our patient had a typical presentation of the disease but ended up having multiple postoperative complications.An 82-year-old Caucasian woman, with a history of hypertension, depression, hypothyroidism, dyslipidemia, carotid endarterectomy and coronary artery disease, presented with a four-day history of nausea, bilious vomiting and epigastric pain radiating to her left scapula. Her home medications included sertraline, atenolol, calcitriol, levothyroxine, tolterodine, omeprazole, aspirin and atorvastatin. She denied smoking, use of alcohol or drug abuse. On examination, she appeared lethargic but not in acute distress. She was afebrile and had a blood pressure of 157/64 mmHg. Examination of her abdomen revealed abdominal distension, epigastric tenderness, tymp
Diverticulitis complicated by pylephlebitis: a case report
Mahesh Gajendran, Thiruvengadam Muniraj, Mohamed Yassin
Journal of Medical Case Reports , 2011, DOI: 10.1186/1752-1947-5-514
Abstract: A 62-year-old Caucasian woman with a history of sigmoid diverticulitis presented to our facility with a three-week history of abdominal pain, fevers, chills, loss of appetite and fatigue. Her laboratory test results showed leukocytosis and elevated alkaline phosphatase. A computed tomography scan revealed portal vein thrombosis and a sigmoid diverticulitis with an abscess. Our patient was given pipercillin-tozabactam followed by sigmoid colectomy and loop transverse colostomy. A peritoneal fluid sample culture grew Escherichia coli. Our patient had an uneventful post-operative course and the leukocytosis resolved in the next four days. She improved clinically and was discharged home on ertapenem and enoxaparin. A follow-up computed tomography scan two weeks later showed a new pelvic abscess that was drained by a pigtail catheter but there was no change in the portal venous thrombus. A repeat computed tomography scan one month later revealed resolution of the pelvic abscess but persistence of portal vein thrombus, for which enoxaparin was continued.This is a classic case of pylephlebitis that demonstrates the importance of recognizing that the portal vein thrombus is infected and treating the condition appropriately.Pylephlebitis is defined as septic thrombophlebitis of the portal venous system, usually secondary to infection or inflammation in the abdomen. The common causes include diverticulitis, appendicitis or cholangitis [1]. Pylephlebitis has to be differentiated from the bland portal vein thrombus. Bland portal vein thrombosis is more common than pylephlebitis and the management is different. Here, we present a case of pylephlebitis that complicated the course of a very common pathology, diverticulitis.A 62-year-old Caucasian woman with a history of sigmoid diverticulitis (seven months prior to admission) was admitted for three weeks of sharp intermittent left lower quadrant abdominal pain, low-grade fever, chills, loss of appetite and fatigue. She denied diar
Performance Analysis of the 3GPP-LTE Physical Control Channels
S. J. Thiruvengadam,Louay M. A. Jalloul
EURASIP Journal on Wireless Communications and Networking , 2010, DOI: 10.1155/2010/914934
Abstract:
MOUTH FRESHNERS - USEFUL OR HARMFUL?
Venkatesan Ulaganathan
Otolaryngology Online Journal , 2013,
Abstract: From periods best known to man, aroma or pleasant smell is always welcomed while bad odor with resent. Many methods have been adopted to avoid or mask malodour. Bad odor is considered asdisgusting especially during the periods of intimacy or closer association with others. This article attempts to explain the role played by these mouth freshners.
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