1,801 research outputs found

    Coded Tissue Superharmonic Imaging: An Analytical Study

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    Superharmonic imaging (SHI) benefits medical ultrasound imaging in achieving higher spatial and contrast resolution but gives poor signal-to-noise ratio (SNR) and penetration depth that require careful control on excitation power and frequency. In the present work, coded pulsed excitations (linear frequency modulated and nonlinear frequency modulated signals) are used to evaluate the superharmonic field generation and propagation (coded tissue superharmonic imaging). The evaluation includes the study of parameters such as peak side lobe level, beam width, axial level for analyzing SNR and penetration depth. The results for coded tissue SHI are reported in comparison with conventional SHI and with the performance of coded tissue harmonic imaging and fundamental ultrasound imaging

    Marketing of sweet jelly seeds of palmyra fruit: A study covering the tribal region of South Gujarat, India

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    Palmyra is a naturally occurring vegetation in Gujarat’s southern region, spread randomly overall soil and land types. The major produce utilized from palmyra palm for a livelihood by the tribal community, contributing considerably to their income, is through sales of the immature soft jelly seed nuts of the fruit called “galeli”. The present investigation was carried out to study the marketing cost, margin, and price spread in galeli marketing. Primary data for the period initiating from 2015-16 to 2017-18 were pooled from 50 palmyra palm growers selected randomly representing five tribal villages of Mahua taluka of Surat district in the South Gujarat region. Two marketing channels viz., Channel-I: producer-consumer and Channel-II: producer - retailer - consumer were observed, and the marketing cost incurred on galeli marketing in these channels was worked out, which was `51.64 and 33.94 per hundred galeli, respectively. The highest producer’s share in consumer’s rupee was worked out in channel-I. The study showed that the major constraint faced by 78 per cent of the palmyra palm growers in the marketing of galeli was the poor functioning of the climber equipment and non-remunerative prices for galeli in the local market

    Dynamic Adaptive Control of Mobile Robot UsingRBF Networks

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    In this paper, an adaptive neuro-control systemwith two levels is proposed for the motion control of anonholonomic mobile robot. In the first level, a PD controller is designed to generate linear and angular velocities, necessary to tracka reference trajectory. In the second level, a neural network converts the desired velocities, provided by the first level, intoa torque control. The advantage of the control approach is that, no knowledge about the dynamic model is required, and no synaptic weight changing is needed in presence of robot’s parameter’s variation (mass or inertia).By introducing appropriate Lyapunovfunctions asymptotic stability of state variables and stability of system is guaranteed. The tracking performance of neural controller under disturbances is compared with PD controller. Sinusoidal trajectory and lamniscate trajectories are considered for this comparison

    Questionnaire based assessment of teaching effectiveness during a lecture series on pharmacotherapeutics

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    Background: Lecture is a widely accepted method of teaching & learning. It provides more of surface learning and covers larger text in specified time. However it has a disadvantage that there is no assessment about the extent of knowledge learner receives. Hence, we designed a daily questionnaire based evaluation technique.Methods: Without disclosing the topic, second year MBBS students (mean n=23) after learning from lecture series in Pharmacology, participated voluntarily to a questionnaire based task on eight therapeutic lecture topics. They wrote answers separately in 5-10 minutes before, and after delivery of text without referring to notes i. e. pre-test & post-test. Papers were valued on score basis, data recorded, interpreted and analyzed.  Results: Mean acceptability (81.4%), mean improvement (94%), mean collective maximum score (96%), mean individual maximum score (92%) were observed. 85-100% participants out of total 184 in eight therapeutic lecture topics passed in post-test (None passing in Pre-test) reflected good improvement in cognitive structure.Conclusion: Performance in such tests provides feedback on teaching effectiveness, specificity & adequacy of knowledge gained by learners.

    Neural Modeling and Control of Diesel Engine with Pollution Constraints

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    The paper describes a neural approach for modelling and control of a turbocharged Diesel engine. A neural model, whose structure is mainly based on some physical equations describing the engine behaviour, is built for the rotation speed and the exhaust gas opacity. The model is composed of three interconnected neural submodels, each of them constituting a nonlinear multi-input single-output error model. The structural identification and the parameter estimation from data gathered on a real engine are described. The neural direct model is then used to determine a neural controller of the engine, in a specialized training scheme minimising a multivariable criterion. Simulations show the effect of the pollution constraint weighting on a trajectory tracking of the engine speed. Neural networks, which are flexible and parsimonious nonlinear black-box models, with universal approximation capabilities, can accurately describe or control complex nonlinear systems, with little a priori theoretical knowledge. The presented work extends optimal neuro-control to the multivariable case and shows the flexibility of neural optimisers. Considering the preliminary results, it appears that neural networks can be used as embedded models for engine control, to satisfy the more and more restricting pollutant emission legislation. Particularly, they are able to model nonlinear dynamics and outperform during transients the control schemes based on static mappings.Comment: 15 page

    Leptogenesis bound on neutrino masses in left-right symmetric models with spontaneous D-parity violation

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    We study the baryogenesis via leptogenesis in a class of left-right symmetric models, in which DD-parity is broken spontaneously. We first discuss the consequence of the spontaneous DD-parity breaking on the neutrino masses. Than we study the lepton asymmetry in various cases, from the decay of right handed neutrino as well as the triplet Higgs, depending on their relative masses they acquire from the symmetry breaking pattern. The leptogenesis bound on their masses are discussed by taking into account the low energy neutrino oscillation data. It is shown that a TeV scale leptogenesis is viable if there are additional sources of CP violation like domain wall originating from the spontaneous DD-parity violation.Comment: 32 pages (revtex), 12 eps figures, clarifications are added in section VII, A new section VIII is added, useful references are added. Journal version, To appear in Phys. Rev.

    LOW ALTITUDE AIRSHIPS FOR SEAMLESS MOBILE COMMUNICATION IN AIR TRAVEL

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    The Aviation Administration policy prohibits the use of mobile phones in Aircraft during transition for the reason it may harm their communication system due to Electromagnetic interference. In case the user wants to access cellular network at higher altitudes, base station access is a problem. Large number of channels are allocated to a single user moving at high speed by various Base Stations in the vicinity to service the request requiring more resources. Low Altitude Platforms (LAPs) are provided in the form of Base stations in the Airships with antennas projected upwards which has direct link with the Ground Station. LAPs using LongEndurance Multi-Intelligence Vehicle (LEMVs) equipped with an engine for mobility and stable positioning against rough winds are utilized. This paper proposes a system that allows the passengers to use their mobiles in Aircraft using LAPs as an intermediate system between Aircraft and Ground station. As the Aircraft is dynamic, it has to change its link frequently with the Airships, MANETs using AODV protocol is established in the prototype using NS2 to provide the service and the results are encouraging

    Effect of different modes of pollination on yield parameters of summer squash (Cucurbita pepo L.) in India

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    Effect of different modes of pollination, viz., without insect pollination, hand-pollination, open-pollination and open-pollination + hand-pollination on yield parameters of 4 summer squash (Cucurbita pepo L.) hybrids viz., Parikrama, Chandra, Chamatkar and Gold Queen was studied at Research Farm of the Department of Entomology, CCS Haryana Agricultural University, Hisar during 2014. Irrespective of different hybrids, the treatment openpollination + hand-pollination and open-pollination produced the maximum number of fruits per plant (73.50 and 71.25%, respectively) followed by hand-pollination (59.08%) and no fruits were observed (0% fruit set) under without insect pollination treatment. Average fruit weight, fruit polar diameter and equatorial diameter were maximum (135.30 g, 3.74 cm and 3.47 cm, respectively) under open-pollination + hand-pollination, while these were minimum (94.81 cm, 2.14cm and 2.48 cm, respectively) under hand-pollination treatment. These results indicate that honey bees as well as wild pollinators are utmost essential for pollination of summer squash flowers and thus increasing fruit size and yield. Therefore pollinators conservation practices should be followed in summer squash growing areas for getting higher yield and returns

    High Frequency Transducer Development for Ultrasonic Tests on Ceramic Components

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    The detection of critical flaws in ceramics requires the use of high frequency ultrasonics. Whilst shorter wavelengths are necessary to detect low micrometer range flaws, so the higher the frequency, the higher the attenuation and so ultimate power and sensitivity is required from examining transducers. This paper outlines the development of such devices. Satisfactory transducers in the frequency range 30–100 MHz are not available commercially and the characteristics of a number of piezoelectric materials for the purpose of their development are being established. Properties such as composition, electrodes, backing and lenses are being investigated
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