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Holographic optics-based schlieren diffraction interferometer
No full textThis paper describes a scheme that uses holographic optics for realization of schlieren diffraction interferometer. The interferometer has been realized with single holographic optical element in conjunction with a collimated beam and the focal plane-modifying element. Multiplexing ability of holographic optics also enables simultaneous operation of more than one technique such as schlieren, shadowgraph and interferometric techniques. Combined schemes where one or more techniques could be applied simultaneously are useful for detailed investigations of phenomena like flow of compressible fluids, because each method has its own characteristic strengths and weaknesses. Procedures for the generation of holographic optical element and realization of various schemes have been presented.
KUMAR Raj ; KAURA Sushil K. ; CHHACHHIA D. P. ; MOHAN D. ; AGGARWAL A. K.
Comparative study of carbon nanotube dispersion using surfactants
No full textDispersion of carbon nanotubes (CNTs) is a challenging task for their utilization in nanoscale device applications. This account reports a comparative analysis on dispersion of multiwalled carbon nanotubes (MWNTs) with four surfactants-Triton X-100, Tween 20, Tween 80, and sodium dodecyl sulfate (SDS). Among the four surfactants, Triton X-100 and SDS provide maximum and minimum dispersion, respectively. Dispersion of MWNTs has been characterized with UV-vis spectroscopy and transmission electron microscopy (TEM). TEM results are in agreement with the UV-vis measurements. The experimentally observed trend of dispersing power of surfactants is consistent with their chemical structures. An optimum CNT-to-surfactant ratio has been determined for each surfactant. This parameter is shown to affect the nanotube dispersion significantly. Surfactant concentration above or below this ratio is shown to deteriorate the quality of nanotube dispersion. TEM analysis of a high-surfactant-concentration sample enables us to construct a plausible mechanism for decrease in CNT dispersion at high surfactant concentration, consistent with the UV-vis observations. Temperature stability of the surfactant is another important factor affecting the quality of CNT dispersio
Structure of boundary diffraction wave revisited
No full textThe physically appealing boundary diffraction wave theory which suggests that diffraction patterns arise due to interference of an undisturbed (geometrical) wave and the boundary diffraction wave generated by edge of the diffracting aperture, simplifies the solution of diffraction problems by reducing the Fresnel-Kirchhoff surface integral into a line integral over the illuminated boundary of the diffracting aperture. The present work reports experimental investigations carried out on the structure of the boundary diffraction wave. It has been shown that the boundary diffraction wave is continuous behind the diffracting aperture and apparently there does not exist any discontinuity at the geometrically light to shadow transition boundary, as is required by the theory
Microcontroller based portable instrument for determination of nickel in edible oils
Get PDFA microcontroller (μC) 89C51RD2BN based portable instrument has been developed for determination of nickel (Ni) concentration in edible oil using dimethylglyoxime method. An LED has been used as a light source with peak wavelength at 450 nm. Silicon photodiode is used as a detector having peak spectral response at 550 nm
Optical and electrical characterization of conducting polymer-single walled carbon nanotube composite films
No full textThe optical and electrical properties of the conducting polymer poly(3-hexylthiophene) and single walled carbon nanotube (SWCNT) composites have been investigated. The composites were prepared by dispersing carbon nanotubes in the polymer matrix already dissolved in 1,2-dichlorobenzene. The optical absorption, photoluminescence (PL) and electrical conductivity of the composite was studied as a function of SWCNT concentration in the solution. The absorption coefficient of the polymer was found to be unaffected upto a SWCNT concentration 5% w/w. However a minor decrease in the absorption in visible region was observed for higher SWCNT concentrations. The intensity of PL emission from the composite was measured and was found to decrease with the increase in SWCNT concentration. For a SWCNT concentration of 30% w/w, ∼90% of the PL was quenched, indicating an ultra fast transfer of photoinduced charges from donor polymer to acceptor SWCNT. Direct current conductivity of the composite film was found to increase rapidly with the increase in SWCNT concentration and an increase of ∼5 orders of magnitude was observed for a 30% w/w concentration. The enhancement in conductivity is explained in terms of percolation theory with an estimated percolation threshold of 2% w/w
Fiber optic interrogator based on colorimetry technique for in-situ nitrate detection in groundwater
Get PDFNitrate poisoning occurs when nitrite is absorbed into the blood, where it changes the red-colored blood pigment, called hemoglobin, to methemoglobin. Hemoglobin carries oxygen from the lungs to the other tissues, but methemoglobin cannot carry oxygen. Poisoning occurs when the methemoglobin concentration in the blood stream is so high that the oxygen carrying capacity of the blood is reduced to a critical level. Over the years nitrate contamination has acquired alarming proportions due to seepage of nitrates of fertilizers into the soil. Though several methods of monitoring nitrate concentration have been devised with some success, there is still a persistent need for devising easily deployable and in-situ techniques for monitoring nitrates in groundwater. Fiber optic techniques are capable of meeting these requirements, besides offering several other important advantages. Fiber optic nitrate detection sensors have thus become quite attractive and are currently being investigated to address the high costs associated with the existing nitrate concentration monitoring procedures. This paper describes fiber optic interrogator for in-situ nitrate detection in groundwater based on colorimetry technique
Analysis of rotary electrical discharge machining characteristics in reversal magnetic field for copper-en8 steel system
No full textThe material removal rate (MRR), along with the
electrode wear rate (EWR), plays an important role in
analysing machine output during electrical discharge
machining. This work focuses on the improvement of
machine output by introducing an induced magnetic field
on the workpiece during rotary electrical discharge machining (REDM) of EN-8 steel with a rotary copper
electrode. The workpiece was placed inside the induced
magnetic field, wherein polarity of the magnetic field gets
reversed periodically. Using Taguchi’s recommended design
of experiments, we initially conducted experiments
with eight input parameters at different levels . Significant parameters were identified with the help of the signal-tonoise ratio and ANOVA. Finally, another set of experiments
Design and development of thermistor based gas flow measurement system for anaesthesia ventilator
Get PDFThis paper describes design and development of a gas flow measurement system, which is particularly helpful for airflow measurement in anaesthesia ventilator. The system measured accurately, required range (0-70 l/m), of airflow for anaesthesia ventilator. Main advantages of developed technique are simplicity of design, dynamic stability and fast response time. Thermistor based hardware design associated with graphical approach has been developed successfully and incorporated in indigenous prototype of anaesthesia ventilator
Effect of frequency and amplitude of FES pulses on muscle fatigue during toning of muscles
Get PDFThis study presents effects of frequency and amplitude of stimulation pulses on muscle contraction. The experiments are on a complete paraplegic patient with injury level between T4 and T5. Number of contraction episode before fatigue has been more for low frequency and low voltage stimulation
Design and development of multi parameter probe to measure temperature and hardness inside snow microstructure
Get PDFCSIO Chandigarh has developed a portable Multi Parameter Probe (MPP) to measure temperature and hardness in snow pack. MPP has been tested in snow bound areas in and around Manali in association with SASE (DRDO). In this paper, designing of MPP and field test performance results provide valuable assistance in the study of snow and avalanche pattern over a period of time, thus improving research accuracy and validating research findings