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Formaldehyde concentration measuring system: an optoelectronic device
Get PDFThe paper describes development of an optoelectronics system, which involves the use of ultra-bright yellow LED (λ, 583nm) as light source. BPW21 photodiode (relative spectral sensitivity, < 90 %, 500–600nm) is used as detector for measurement of formaldehyde concentration. The system is based on the reaction of formaldehyde with chromotropic acid in acidic medium. Violet colour, produced after the reaction, is used to measure the concentration (0.5 - 10 ±0.02 ppm) in wate
DATA HIDING IN DIGITAL IMAGES: A REVIEW
No full textIn this paper we will overview the data hiding techniques in digital images. We will describe how one can use steganography to hide information in a digital image. Steganography is the basis for many of the digital watermarking techniques currently being developed, and is related to cryptography. Recent developments in digital copyright protection schemes have attracted attention in data hiding techniques. Secret embedding of ownership data in the contents of digital image is one way to establish and protect ownership of digital image. Recent developments in data hiding will be reviewed in this paper
Fiber Optic Colorimetric Technique for in-situ Measurement of Corrosion in Civil Structures
No full textDesign and characterization of a direct current glow discharge lamp for analytical applications
No full textThis paper describes a compact, small volume direct current glow discharge lamp operating at low wattage for atomic emission spectrometric analysis and its process optimization for copper and brass solid samples. The design aspects, fundamental characteristics and analytical performance are described in detail. The discharge is observed end-on, with water-cooled cathode surface parallel to the spectroscopic entrance slit. The anode diameter is 7 mm and the minimum sample diameter required is 20 mm. The sample is located outside the lamp for easy access and interchangeability. The lamp is powered by a dc power supply capable of delivering 300 mA (max.) and 1500 V. The studies of fundamental characteristics include the current–voltage relationship and their dependence on pressure and the emission intensity of copper spectral line (324.7 nm). The studies were made in the pressure range of 2–7 mbar. Long-term stability of optical emission spectra was also recorded to be within ±0.75%. The performance of the lamp is quite linear in the pressure range 3.5–7 mbar at an applied voltage of about 450 V
Development of portable metal oxide gas sensor for the detection of foul odour
Get PDFHalitosis or oral malodour originates with the anaerobic bacterial degradation of sulphur containing amino acids within the oral cavity resulting in the emission of hydrogen sulphide (H2S), methyl mercaptan (CH3SH) and dimethyl sulphide (CH3SCH3), collectively known as volatile sulphur compounds (VSCs). The sensing of VSCs is needed for dentistry as well as for auto-ventilation applications. This paper discusses the design and development of the portable and low cost metal oxide based gas sensor for the foul odour applications. The substrate design, the sensor parameters and the proposed in-house works are described
Interferometry based security hologram readable with an encoded key hologram
Get PDFA simple and cost-effective method for making security holograms has been presented, which incorporates holographic interferometry as verification feature in addition to spatially separated sharp focus spots. When the security hologram is illuminated with decoding reconstructing beam generated from an encoded key hologram, two spatially separated sharp focus spots emerge at the predefined positions and can be read through a photoelectric detector array. In addition, these focused spots upon divergence in longitudinal direction further generate specific kind of interferometric fringe patterns of random profile contained in them, which are suitable for further visual inspection. These machine-readable and visual verifiable features can be used for better counterfeit-resistant security codes in embossed holograms. Recording schemes for the formation of such security holograms and typical experimental results have been presente
Encoded Reference Wave Security Holograms with Enhanced Features
No full textA simple and cost effective two-step method for making encoded reference wave security holograms with enhanced features, which are readable with an encoded key hologram, has been presented. In the final reading process, two spatially separated sharp focus spots (bright spots) emerge only when the security hologram is illuminated by the decoding, reconstructing beam, generated from the encoded key hologram. In addition these focused spots, upon divergence in the longitudinal direction, further generate variable interferometeric features, i.e. circular and linear interference fringe patterns contained respectively in them. Since the verification/identification pattern in these security holograms are variable interferometric features in addition to the spatially separated sharp focus spots, this type of security hologram is suitable for both visual as well as machine inspection. They can also be used as security codes for better protection against counterfeiting embossed holograms. Recording schemes for the formation of such security holograms and typical experimental results have been presented
Microcontroller based oscillation monitoring system for the safety of railway vehicles with high storage capacity and real time warning facility
Get PDFAn Advanced portable instrument to monitor, detect, and record the horizontal and vertical accelerations of the railway vehicles (railway coaches, wagons and locomotives, etc.) as well as of railway tracks has been designed and developed by incorporating the state of the art technology suitable for this purpose. The design/technology has been perfected by conducting repeated field trials on the instrument in association with the engineers of RDSO, Lucknow. The designed instrument based on 89C52 Micro-controller technology, is a major step in the direction of advance instrumentation for Indian Railways. Oscillation monitoring system continuously measures vertical and lateral accelerations at any desired location on the floor of a railway vehicle and simultaneous measurement of distance from fixed points of track on real time basis. It is an advanced portable instrument to measure and record oscillations of railway vehicle, while in motion. The system is so rugged that it can work in non air-conditioned environment and withstand vibration of ‘1g’ in all three orthogonal axes without any problem. Based on this measurement, analysis can be carried out on railway track conditions. The unit has been designed with large storage capacity and displays locations of bad spots along with other required information, which are registered over the threshold value
Characterization of Nano-scale Roughness in Single Point Diamond Turned Optical Surfaces using Power Spectral Density Analysis
Get PDFPower spectral density (PSD) distribution provides an accurate measure of roughness of an optical surface. This article presents an analysis of optical surface roughness generated by single point diamond turning (SPDT) using PSD. For this study, flat 60 mm diameter aluminium-6061 samples are machined for varying tool feed rates, while keeping the other machining parameters constant. The 1-D PSD distributions are computed from the surface roughness data obtained by mechanical profilometer. The PSD distribution of the surface roughness profile is composed of primarily three periodic components, which are correlated to the tool feed rate, material induced vibrations and machine-tool vibrations. An attempt has been made to identify their individual contributions in PSD estimates. This study helps in improving the surface quality by selecting optimum process parameters
Realization of an optical interferometer based on holographic optics for real-time testing of phase objects
No full textAbstract. The paper describes a simple and cost e®ective method for the realization
of an optical interferometer based on holographic optics, which use minimal bulk optical
components. The optical arrangement in the proposed method involves a very simple
alignment procedure and inexpensive holographic recording material is used in the forma-
tion of holographic optical elements. The proposed interferometer set-up is quite suitable
for performing optical test studies on phase (transparent) objects in real-time. Recording
schemes for the formation of holographic optical elements and the related technique for
the realization of the interferometer set-up along with the experimental results have been
presented