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A NOVEL MOMENT-BASED SHAPE DESCRIPTION AND RECOGNITION TECHNIQUE
No full textThe task of recognition of objects from their two dimensional views has been attempted in the past using different techniques. The general requirement has been to represent the original two dimensional iconic image to some compact symbolic description to facilitate matching and storage requirements. Often, the quantitative symbolic description that is needed from an image is more likely to be of the order of tens of real numbers. Another requirement is to recognise as identical two patterns which differ in location, rotation or size. A further requirement is to have description sensitive enough to take care of all the features in an object and robust and flexible enough to disregard the minor differences due to noise and image acquisition system defects. The invariance to rotation and translation is achieved with the use of global techniques such as moments, Fourier descriptors and the cyclic chain codings of polygonal approximation of the objects. The scale invariance is also reported to be achieved with some additional computational cost. Such final description is termed as an n-dimensional feature vector represented as a point in n-dimensional space. Minimum-distance object classification can efficiently be used with such a descriptio
A Simple Electronic Tongue
No full textIn this work a novel electronictongue (ET) using Fourier transform impedance spectroscopy has been demonstrated. Odd random phase multisine waveform has been used as an excitation signal. Texas Instruments’ PCM2900B USB audio CODEC chip has been used as a signal generation and an acquisition module for the ET. The acquired impedance features have been further subjected to Principal Component Analysis (PCA) for dimensionality reduction and Support Vector Machines (SVM) for pattern classification. A good classification accuracy has been achieved for single specie samples (taste samples), multi-species samples (water) and complex samples (tea). Also, the performance of the proposed system has been measured in terms of qualitative performance parameters namely, false positive rate, false negative rate, sensitivity rate and specificity rate
TiO2 nanofibres decorated with green-synthesized PAu/Ag@CQDs for the efficient photocatalytic degradation of organic dyes and pharmaceutical drugs
No full textOrganic pollutants such as dyes and pharmaceutical drugs have become an environmental menace, particularly in water bodies owing to their unregulated discharge. It is thus required to develop an economically viable and environment-friendly approach for their degradation in water bodies. In this study, for the first time, we report green route-synthesized plasmonic nanostructures (PM-CQDs (where M: Au and Ag)) decorated onto TiO2 nanofibers for the treatment of toxic dye- and pharmaceutical drug-based wastewater. PM-CQDs are efficaciously synthesized using carbon quantum dots (CQDs) as the sole reducing and capping agent, wherein CQDs are derived via a green synthesis approach from Citrus limetta waste. The characteristic electron-donating property of CQDs played a key role in the reduction of Au3+ to Au0 and Ag+ to Ag0 under visible light irradiation to obtain PAu-CQDs and PAg-CQDs, respectively. Thus, the obtained CQDs, PAu-CQDs, and PAg-CQDs are loaded onto TiO2 nanofibers to obtain a PM-CQD/TiO2 nanocomposite (NC), and are further probed via transmission electron microscopy, scanning electron microscopy and UV-visible spectrophotometry. The degradation of organic pollutants and pharmaceutical drugs using methylene blue and erythromycin as model pollutants is mapped with UV-vis and NMR spectroscopy. The results demonstrate the complete MB dye degradation in 20 minutes with 1 mg mL−1 of PAu-CQD/TiO2 NC, which otherwise is 30 minutes for PAg@CQD/TiO2 dose under visible light irradiation. Similarly, the pharmaceutical drug was found to degrade in 150 minutes with PAu-CQD/TiO2 photocatalysts. These findings reveal the enhanced photocatalytic performance of the green-synthesized Au decorated with TiO2 nanofibers and are attributed to the boosted SPR effect and aqueous-phase stability of Au nanostructures. This study opens a new domain of utilizing waste-derived and green-synthesized plasmonic nanostructures for the degradation of toxic/hazardous dyes and pharmaceutical pollutants in water
Solving Fresnel equation for refractive index using reflected optical power obtained from Bessel beam interferometry
No full textThis work demonstrates an interferometric technique to estimate the reflected powers from dielectric interfaces and the reflection coefficient using the Fresnel equation for measurement of the refractive index (RI) of liquid samples. It uses low-coherence common-path optical interferometry that is commonly used for optical imaging. A uniquely designed optical fiber tip generating a high-quality non-diffractive Bessel beam probes liquid samples in a glass container non-invasively. The light reflected from different interfaces of the container is recollected by the same optical fiber tip. The reflected beams interfere with the reference beam generated at the fiber tip itself. This interference spectrum is further processed using fast-Fourier transform to measure reflected powers from the respective interfaces. The acquired powers are used to solve the Fresnel equation to find RI of liquid samples. As a proof of concept, experiments have been performed on several liquid samples including turbid media such as blood. This non-invasive interferometric technique could also be an ideal example confirming the Fresnel equation for reflection of light. Unlike other optical fiber-based RI sensors, this technique does not require temperature compensation. The method can be employed for inspection of the production process in terms of RI in pharmaceutical and chemical process plants, etc