42 research outputs found
Exploration of Non-MPB PZT Compositions for High Piezoelectric Voltage Sensitive 0-3 Composites
No full textPiezoelectric composites provide an opportunity to make robust piezoelectric sensors. These materials are based on piezoelectric ceramic powders or particles, which are dispersed in a polymer matrix. In most cases, piezoelectric composites use the same ceramic compositions as the ones used in piezoelectric ceramics. These compositions consist of lead zirconium titanate (PZT) with a composition close to the morphotropic phase boundary (MPB). This research work focuses on exploring the performance of non-MPB compositions of PZT ceramic particles in order to obtain high voltage sensitive 0-3 PZT-Epoxy composites. The PZT ceramic compositions (PbNb0.01[ZrxTi(1-x)]O3), ranging from pure tetragonal lead titanate (x=0) to rhombohedral (x=0.80) were prepared using the mixed oxide method. These ceramic particles were characterized using XRD, SEM and particle size analyser and were used to prepare both sintered ceramics and 0-3 PZT-epoxy composites. The effect of the ceramic filler composition on the dielectric and piezoelectric properties of the PZT-Epoxy composites was investigated. Unlike PZT ceramics, the best piezoelectric properties were not observed in the MPB-based composites but in the pure tetragonal phase. It was observed that the dielectric constant of the ceramic particles had minimal influence on the effective dielectric constant (?r) and the piezoelectric charge constant (d33) of the piezoelectric composite due to the depolarization effect of the high dielectric filler materials. The experimentally determined values of the dielectric and piezoelectric properties of the piezoelectric composites were validated using analytical models. The influence of electric fatigue on the polarization of the PbTiO3 (PT) and morphotropic phase boundary (MPB) based composites were also examined. Finally, a material selection criterion was proposed in order to develop piezoelectric composites with high voltage sensitivity. This general material selection criterion is not limited to PZT based ceramics but is also applicable to lead-free ceramic filler materials. Thus, the current research work paves the way for the development of environmental friendly lead-free piezoelectric composites devices with enhanced sensory properties.Novel Aerospace Materials (NovAM)Mechanics, Aerospace Structures & MaterialsAerospace Engineerin
Numerical Analysis on a Double Pipe Heat Exchanger with Twisted Tape Induced Swirl Flow on Both Sides
No full textAbstractTwisted tape inserts are widely used for enhancing heat transfer in heat exchangers. They enhance heat transfer by inducing swirl flow in the flow channel, thereby enabling good mixing within the fluid and by increasing the effective flow length of the flow channel. They also increase pressure drop but their overall performance is found to be advantageous in many cases. In this work, an attempt is made to analyse the performance of a modified double pipe heat exchanger with twisted tape induced swirl flow on both sides. The numerical analysis were done in turbulent flow conditions with twisted tape inserts of twist ratio 5 and 3. The results obtained are validated using established correlations available in the literature. The fin effect of twisted tape is also discussed
Enzyme liquefaction and development of novel value added products from Wood apple (Feronia elephantum)- an untapped forest resource
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
BCG and beyond: unlocking new frontiers in TB vaccine development
Get PDFWith over 10 million new cases and 1.6 million deaths annually, tuberculosis (TB) continues to be a significant worldwide health-burden. To assist in curbing the spread of TB, the century-old BCG, which is a live-attenuated vaccine, is now the only licensed TB vaccine used in humans. However, BCG’s limited efficacy and poor antigenicity in adults have evoked the need to design new vaccines against TB. The limited parameter is the availability of potent antigens; as a consequence, it is imperative to study the Mycobacterium tuberculosis (Mtb)-specific antigens that can provide a stronger immune response if included in vaccine candidates. Through this review, we aim to concentrate on the progress of current vaccine-candidates undergoing preclinical and clinical-studies. Moreover, it is not the pathogen but the genetics of the host that plays an essential role in fine tuning the immune-response and susceptibility to TB. Over the past 50 years, a systematic approach to treating TB patients has overlooked factors like pharmacokinetics, immune-response, and treatment duration. Henceforth, this review highlights the precision medicine-guided approach considering genetic makeup and host immunity that could influence clinical management choices. The consolidated review will shed light on advancements in vaccine-candidates, which can be harnessed in prophylactic development against TB
Design of AES Architecture With Area and Speed Tradeoff
No full textAbstractAES, is the well-accepted cryptographic algorithm which could be utilized to ensure security of electronic information since it is proven to be resistive to most of the attacks. In this work, we present the AES-128 encryption and decryption circuit using area optimized iterative architecture. Here the technique used to obtain a lower area delay product is to map the transformations to 8 bit hardware while keeping the datapath to be 128 bit. A control unit is designed to keep track of the transformations. The proposed architecture have been implemented on the most recent Xilinx Spartan FPGA, their area and delay are compared with the previous works and it is proved that proposed technique has lower area coverage and delay
Transformation of Coastal Settlements Due to Tourism
No full textAbstractHuman interventions like industrialisation, urbanisation&commercialisation in ecologically vulnerable coastal areas often lead to deterioration of the environment. Tourism is a major economic activity which can bring significant transformations in the lives of people in a destination. Some of the changes can be beneficial in the form of economic growth and infrastructural developments leading to overall improvement in living standards. At the same time, it can also lead to adverse environmental impacts due to increased commercialisation, radical changes in land use, growth of crimes etc. Studies conducted in the town of Varkalarevealed that the coastal settlements are undergoing rapid transformations as a result of uncontrolled tourism activity in recent years. Unless immediate corrective measures are taken by the authorities, this will lead to socio- economic,physical and environmental degradation of the coastal region which will adversely affect the tourist inflow into the destination. This paper gives an overview about impacts of tourism development in coastal areas and the impact of tourism on the coastal environment of Papanasam beach in Varkala
A study into utilising idle computation cycles on remote machines in a networked environment
No full textThis thesis was scanned from the print manuscript for digital preservation and is copyright the author.
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INTRACAVITY LASER SPECTRA OF METHANE 790 AND 861 NM BANDS AT LOW TEMPERATURES
No full textAuthor Institution: Department of Chemistry and Center for Molecular Electronics, University of Missouri, St Louis, MO 63121-4499Methane is a very important molecule in planetary studies. The intracavity laser spectroscopy is used to collect the spectra of methane in the visible to near infrared region. A special intracavity cryogenic chamber is used to record the spectra of methane at various low temperatures from 161K to 99K. Spectra of methane for 790 and 861 nm bands have been recorded and absorption coefficients derived from the spectra for both these bands at different low temperatures are presented
