Recursos de colección

ETD at Indian Institute of Science (2.878 recursos)

Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.

Instrumentation (isu)

Mostrando recursos 1 - 20 de 59

  1. Poly-Vinylidene Fluoride Based Vibration Spectrum Sensors and Energy Harvestors

    Nyayapati, Mahidhar Ramesh
    Mechanical vibrations in large structures such as buildings, bridges, dams and critical frequencies in large machinery generally have low frequencies (100Hz-1000Hz). To monitor large areas of such structures we need huge network of low cost, easily manufacturable, self-powered and stand-alone vibration spectrum sensors. The sensors should also consume very little power during their overall operation cycle and have moderately high frequency resoultion. The thesis provides mathematical analysis, design and development of stand-alone, low frequency vibration spectrum analyzer .A mechanically stretched polymer piezoelectric membrane, which has a fixed length and tension, can act as a single frequency detector due to its unique...

  2. Poly-Vinylidene Fluoride Based Vibration Spectrum Sensors and Energy Harvestors

    Nyayapati, Mahidhar Ramesh
    Mechanical vibrations in large structures such as buildings, bridges, dams and critical frequencies in large machinery generally have low frequencies (100Hz-1000Hz). To monitor large areas of such structures we need huge network of low cost, easily manufacturable, self-powered and stand-alone vibration spectrum sensors. The sensors should also consume very little power during their overall operation cycle and have moderately high frequency resoultion. The thesis provides mathematical analysis, design and development of stand-alone, low frequency vibration spectrum analyzer .A mechanically stretched polymer piezoelectric membrane, which has a fixed length and tension, can act as a single frequency detector due to its unique...

  3. Ultrafast Laser Inscribed Waveguides on Chalcogenide Glasses for Photonic Applications

    Sabapathy, Tamilarasan
    Chalcogenide glasses are highly nonlinear optical materials which can be used for fabricating active and passive photonic devices. This thesis work deals with the fabrication of buried, three dimensional, channel waveguides in chalcogenide glasses, using ultrafast laser inscription technique. The femtosecond laser pulses are focused into rare earth ions doped and undoped chalcogenide glasses, few hundred microns below from the surface to modify the physical properties such as refractive index, density, etc. These changes are made use in the fabrication of active and passive photonic waveguides which have applications in integrated optics. The first chapter provides an introduction to the...

  4. Studies on AgInS2 Films as Absorber Layer for Heterojunction Solar Cells

    Sunil, Maligi Anantha
    Currently conventional sources like coal, petroleum and natural gas meet the energy requirements of developing and undeveloped countries. Over a period of time there is high risk of these energy sources getting depleted. Hence an alternate source of energy i.e. renewable energy is the need of the hour. The advantages of renewable energy like higher sustainability, lesser maintenance, low cost of operation, and minimal impact on the environment make the role of renewable energy sources significant. Out of the various renewable energy sources like solar energy, wind energy, hydropower, biogas, tidal and geothermal, usage of solar energy is gradually increasing....

  5. Studies on AgInS2 Films as Absorber Layer for Heterojunction Solar Cells

    Sunil, Maligi Anantha
    Currently conventional sources like coal, petroleum and natural gas meet the energy requirements of developing and undeveloped countries. Over a period of time there is high risk of these energy sources getting depleted. Hence an alternate source of energy i.e. renewable energy is the need of the hour. The advantages of renewable energy like higher sustainability, lesser maintenance, low cost of operation, and minimal impact on the environment make the role of renewable energy sources significant. Out of the various renewable energy sources like solar energy, wind energy, hydropower, biogas, tidal and geothermal, usage of solar energy is gradually increasing....

  6. Development of Handheld Impedance Spectroscopy Instrument Suitable for Biological Tissue Characterization

    Naik, Dinesh
    Impedance spectroscopy (IS) is a powerful and sophisticated tool to characterize intrinsic electrical properties of any materials and its interface, measuring the electric and transport properties of the materials, investigating the mechanism of electrochemical reaction etc. The fundamental principle of IS is the measurement of the impedance (equivalent to resistance in DC analysis) of the system under investigation over a wide frequency range. The IS study provides quantitative information about the conductance, the dielectric coefficient, the static properties of the interfaces like contact resistance, and its dynamic change due to adsorption or charge transfer phenomenon. Commercial Impedance analyzers that are...

  7. Development of Handheld Impedance Spectroscopy Instrument Suitable for Biological Tissue Characterization

    Naik, Dinesh
    Impedance spectroscopy (IS) is a powerful and sophisticated tool to characterize intrinsic electrical properties of any materials and its interface, measuring the electric and transport properties of the materials, investigating the mechanism of electrochemical reaction etc. The fundamental principle of IS is the measurement of the impedance (equivalent to resistance in DC analysis) of the system under investigation over a wide frequency range. The IS study provides quantitative information about the conductance, the dielectric coefficient, the static properties of the interfaces like contact resistance, and its dynamic change due to adsorption or charge transfer phenomenon. Commercial Impedance analyzers that are...

  8. Ultrasound-Assisted Diffuse Correlation Spectroscopy : Recovery of Local Dynamics and Mechanical Properties in Soft Condensed Matter Materials

    Chandran, Sriram R
    This thesis describes the development and applications of an extension of DWS which enables the recovery of ‘localized’ mechanical properties, in a specified region of a complex jelly-like object which is inhomogeneous, marked out by the focal volume of an ultrasound transducer, also called the region-of-interest (ROI). Introduction of the sinusoidal forcing creates a sinusoidal phase variation in the detected light in a DWS experiment which modulates the measured intensity autocorrelation, g2 (τ ). Decay in the modulation depth with τ is used to recover the visco-elastic spectrum of the material in the ROI. En route to this, growth of...

  9. Ultrasound-Assisted Diffuse Correlation Spectroscopy : Recovery of Local Dynamics and Mechanical Properties in Soft Condensed Matter Materials

    Chandran, Sriram R
    This thesis describes the development and applications of an extension of DWS which enables the recovery of ‘localized’ mechanical properties, in a specified region of a complex jelly-like object which is inhomogeneous, marked out by the focal volume of an ultrasound transducer, also called the region-of-interest (ROI). Introduction of the sinusoidal forcing creates a sinusoidal phase variation in the detected light in a DWS experiment which modulates the measured intensity autocorrelation, g2 (τ ). Decay in the modulation depth with τ is used to recover the visco-elastic spectrum of the material in the ROI. En route to this, growth of...

  10. Large Area Electronics with Fluids : Field Effect on 2-D Fluid Ribbons for Desalination And Energy Harvesting

    Kodali, Prakash
    This work studies the influence of field effect on large area 2 dimensional ribbons of fluids. A fluid of choice is confined in the channel of a metal-insulator-channel-insulator-metal architecture and is subjected to constant (d.c) or alternating (a.c) fields (de-pending on the application) along with a pressure drive flow. A general fluid would be composed of molecules having certain polarizability and be a dispersion of non-ionic and ionic particulates. The field effect response under pressure driven flow for this fluid would result in electrophoresis, electro osmosis, dielectrophoresis, dipole-dipole interaction and inverse electro osmosis phenomena. Using some of these phenomena we...

  11. Large Area Electronics with Fluids : Field Effect on 2-D Fluid Ribbons for Desalination And Energy Harvesting

    Kodali, Prakash
    This work studies the influence of field effect on large area 2 dimensional ribbons of fluids. A fluid of choice is confined in the channel of a metal-insulator-channel-insulator-metal architecture and is subjected to constant (d.c) or alternating (a.c) fields (de-pending on the application) along with a pressure drive flow. A general fluid would be composed of molecules having certain polarizability and be a dispersion of non-ionic and ionic particulates. The field effect response under pressure driven flow for this fluid would result in electrophoresis, electro osmosis, dielectrophoresis, dipole-dipole interaction and inverse electro osmosis phenomena. Using some of these phenomena we...

  12. Automation of Microscopic Tests for Cyto-diagnostics Using Custom-built Slide Scanner

    Swetha, M
    Optical microscopy is the simplest and the gold standard method adopted for the screening and subsequent diagnosis of various hematological and infectious diseases like malaria, sickle cell disease, tuberculosis etc. In addition to infectious disease diagnosis, its applications range from routine blood tests to the more sophisticated cancer biopsy sample analysis. Microscopy Tests (MTs) follow a common procedural workflow: (1) A technician prepares a smear of the given sample on a glass slide in a specific manner depending on the sample and the disease to be diagnosed; (2) The smeared slide is subsequently exposed to fixative agents and different histochemical...

  13. Design And Development of Linear Moving Magnet Synchronous Motor Based Twin PTC And HTS Level Sensor for LOX Recondenser

    Gour, Abhay Singh
    Cryocoolers are closed cycle devices which produce cooling below 120 K. Usually, one or two linear motors are used to drive one pulse tube cryocooler. Cryocoolers are used for various applications like, cooling of infra red detectors, cryo surgical knife, cryogen recondenser etc. In this thesis the design development and testing of Twin Pulse Tube Cryocooler (TPTC) are discussed. TPTC consists of two pulse tubes driven by dual piston head linear compressor. This dual piston linear compressor is operated using single linear motor. Using this configuration, cooling power is doubled with reduced cost of compressor. The design, fabrication and testing...

  14. Design And Development of Linear Moving Magnet Synchronous Motor Based Twin PTC And HTS Level Sensor for LOX Recondenser

    Gour, Abhay Singh
    Cryocoolers are closed cycle devices which produce cooling below 120 K. Usually, one or two linear motors are used to drive one pulse tube cryocooler. Cryocoolers are used for various applications like, cooling of infra red detectors, cryo surgical knife, cryogen recondenser etc. In this thesis the design development and testing of Twin Pulse Tube Cryocooler (TPTC) are discussed. TPTC consists of two pulse tubes driven by dual piston head linear compressor. This dual piston linear compressor is operated using single linear motor. Using this configuration, cooling power is doubled with reduced cost of compressor. The design, fabrication and testing...

  15. Development Of Deterministic And Stochastic Algorithms For Inverse Problems Of Optical Tomography

    Gupta, Saurabh
    Stable and computationally efficient reconstruction methodologies are developed to solve two important medical imaging problems which use near-infrared (NIR) light as the source of interrogation, namely, diffuse optical tomography (DOT) and one of its variations, ultrasound-modulated optical tomography (UMOT). Since in both these imaging modalities the system matrices are ill-conditioned owing to insufficient and noisy data, the emphasis in this work is to develop robust stochastic filtering algorithms which can handle measurement noise and also account for inaccuracies in forward models through an appropriate assignment of a process noise. However, we start with demonstration of speeding of a Gauss-Newton (GN)...

  16. Shape Optimization Of A Cylilndrical-Electrode Structure To Mimic The Orbitrap

    Ovhal, Ajay Ashok
    The Orbitrap is a mass analyzer that employs an electrostatic field to confine ions. The mass of an ion is determined from the frequency of its axial oscillations in the Orbitrap. The Orbitrap has high resolving power and accuracy. However, the electrodes of the Orbitrap have complicated curved shapes. As a consequence the Orbitrap is not easy to miniaturize. In this thesis we have proposed a class of easily machinable cylindrical-electrode structures to mimic the behavior of an Orbitrap. The proposed structure consists of a single cylinder and many coaxial equally spaced thick rings. A detailed numerical simulation of the cylindrical-electrode...

  17. Studies On Direct Sensor Interface Technology For Launch Vehicle Applications

    Sirnaik, M N
    In a process monitoring/control applications tens to thousands of sensors are used for monitoring system parameters. To achieve overall system goals, their reliable performance is critical. Generally a sensor’s output signal is too small or too noisy and may not be compatible with the input requirements of a Data Acquisition System. The sensor is interfaced to Data Acquisition System, through cabling, junction boxes and Interface Electronics like excitation circuitry, multiplexers, signal-conditioning circuitry etc. An interface or signal conditioning circuit does impedance matching, filtering, multiplexing, pre-amplification, amplification and digitization to make the sensor’s output signal compatible with the Data Acquisition System....

  18. Fiber Bragg Grating Sensors : An Exploration Of Applications In Diverse Fields

    Guru Prasad, A S
    Sensors have become essential elements in human life for safe and comfortable existence in the ever demanding world. Various technologies over decades have contributed in their own way fulfilling innumerable sensing requirements. The discovery of optical sensor technologies has revolutionized the sensing field due to their inherent advantages. Among the large number of fiber optic sensor technologies, FBG based sensors have become widely known and popular within and outside the photonics community and has seen a prominent rise in their utilization. This thesis explores the use of FBG sensors for a wide range of applications scanning across a variety of...

  19. Studies On Bayesian Approaches To Image Restoration And Super Resolution Image Reconstruction

    Chandra Mohan, S
    High quality image /video has become an integral part in our day-to-day life ranging from many areas of science, engineering and medical diagnosis. All these imaging applications call for high resolution, properly focused and crisp images. However, in real situations obtaining such a high quality image is expensive, and in some cases it is not practical. In imaging systems such as digital camera, blur and noise degrade the image quality. The recorded images look blurred, noisy and unable to resolve the finer details of the scene, which are clearly notable under zoomed conditions. The post processing techniques based on computational...

  20. Integrated Gas Sensor - Studies On Sensing Film Deposition, Microheater Design And Fabrication, Interface Electronics Design And Testing

    Velmathi, G
    Recently, there has been an increasing interest in the electronics world for those aspects related to semiconducting gas sensor (SGS) materials. In view of the increasingly strict legal limits for pollutant gas emissions, there is a great interest in developing high performance gas sensors for applications such as controlling air pollution and exhaust gases in automotive industry. In this way, semiconductor gas sensors offer good advantages with respect to other gas sensor devices, due to their simple implementation, low cost and good stability and sensitivity. The first part of the thesis is dedicated to the synthesis, film structural and sensitivity...

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