Design of a PLL with improved locking range and its biomedical applications

This paper describes a phase locked loop employing a low voltage VCO using modified ECL inverter cells. The VCO circuit employed, features a positive feed back scheme to improve the operating frequency. The phase detector used in the PLL also uses a positive feedback scheme to improve the locked range and to reduce supply voltage of operation of the entire circuit. An improvement of locked range of around 35% was obtained from circuit simulation (using PSPICE) as well as from practical circuit, using discrete components. The minimum supply voltage required here is 2.5 volts. Some biomedical applications of this PLL are also proposed.     

Loading Rate Effect on Nanohardness of Soda-Lime-Silica Glass

To understand how hardness, the key design parameter for applications of brittle solids such as glass concerning contact deformation, is affected by loading rate variation, nanoindentation with a Berkovich tip was used to measure the nanohardness of a 330-μm-thick soda-lime-silica glass as a function of loading rate (1 to 1000 mN·s⁻¹). The results showed for the very first time that, with variations in the loading rate, there was a 6 to 9 pct increase in the nanohardness of glass up to a threshold loading rate (TLR), whereafter it did not appreciably increase with further increase in loading rate. Further, the nanohardness data showed an indentation size effect (ISE) that obeyed the Meyer’s law. These observations were explained in terms of a strong shear stress component developed just beneath the nanoindenter and the related shear-induced deformation processes at local microstructural scale weak links. The significant or insignificant presence of shear-induced serrations in load depth plots and corresponding scanning electron microscopic evidence of a strong or mild presence of shear deformation bands in and around the nanoindentation cavity supported such a rationalization. Finally, a qualitative picture was developed for different deformation processes induced at various loading rates in glass.     

Investigation of terminalia (Terminalia belerica Robx.) seed oil as prospective biodiesel source for North-East India

Terminalia (Terminalia belerica Robx.) is available in the northeastern region of India. The fruit of terminalia has some medicinal value and its kernel contains 43% oil. The prospect of terminalia oil for biodiesel production is investigated with reference to some relevant properties. The fatty acid profile of oil extracted from terminalia is found comparable with similar seed oils attempted for biodiesel production in this region. Terminalia oil contains 32.8% palmitic acid, 31.3% oleic acid, and 28.8% linoleic acid. The calorific value and kinematic viscosity of terminalia oil are 37.50 MJ/kg and 25.60 cSt, respectively. The calorific value and cetane number of terminalia FAME are within the acceptable limit of the EN 14214 standard. However, the flash point of terminalia FAME (90 °C) is relatively lower than the minimum required standard. Overall, the properties of biodiesel obtained from terminalia seed conform to the existing biodiesel standard. In addition to assisting the national biodiesel mission, the extension and regeneration of forest areas through terminalia planting would help us to curb the seemingly irreversible trend of de-forestation in the northeast region of India.     

The electro-adsorption chiller: a miniaturized cooling cycle with applications to micro-electronics

A novel modular and miniature chiller is proposed that symbiotically combines adsorption and thermoelectric cooling devices. The seemingly low efficiency of each cycle individually is overcome by an amalgamation with the other. This electro-adsorption chiller incorporates solely existing technologies. It can attain large cooling densities at high efficiency, yet is free of moving parts and comprises harmless materials. The governing physical processes are primarily surface rather than bulk effects, or involve electron rather than fluid flow. This insensitivity to scale creates promising applications in cooling personal computers and other microelectronic appliances.     

A unified scheme for adaptive stroke-based rendering

This paper presents a comprehensive scheme for automatically generating a broad class of artistic illustrations from photographs. Using strokes as the major building blocks, our system optimizes the stroke attributes subject to the desired rendering style. The stroke attributes are computed adaptively to enable importance-based control of the abstraction level at each pixel. We propose a novel outline detection and refinement paradigm called edge painting to construct an outline map, and from which to derive the pixel-wise importance. We also introduce an adaptive bilateral filter to adaptively guide the curved stroke directions based on the importance map. Given the outline, importance, and direction maps, the system creates the illustration via selecting the representative colors, setting the style parameters, and optimizing the stroke attributes based on simulated annealing. The experimental results show that our scheme facilitates automatic production of artistic illustrations in a wide range of rendering styles.     

Improved quality of reconstructed images using floating point arithmetic for moment calculation

Zernike moments which are superior to geometric moments because of their special properties of image reconstruction and immunity to noise, suffer from several discretization errors. These errors lead to poor quality of reconstructed image and wide variations in the numerical values of the moments. The predominant factor, as observed in this paper, is due to the discrete integer implementation of the steps involved in moment calculation. It is shown in this paper that by modifying the algorithms to include discrete float implementation, the quality of the reconstructed image improves significantly and the first-order moment becomes zero. Low-order Zernike moments have been found to be stable under linear transformations while the high-order moments have large variations. The large variations in high-order moments, however, do not greatly affect the quality of the reconstructed image, implying that they should be ignored when numerical values of moments are used as features. The 11 functions based on geometric moments have also been found to be stable under linear transformations and thus these can be used as features. Pixel level analysis of the images has been carried out to strengthen the results.     

Interferometer for use in wave-front testing with a cross slit

A simple and novel interferometric setup for wave-front testing that uses a cross slit is described. In this method, the test beam illuminates a cross slit placed at the front focal plane of a Fourier lens. It selects two orthogonal slices from the test beam, and the interference of these two beams is observed at a slightly defocused plane near the back focal plane. Fringes of different conical forms (circular, elliptical, or hyperbolic) so obtained can be used for testing a coherent wave front in general. The theory, supported by some experimental results, is presented. An application of the method to the study of the nature of asymmetry in the beam profile of a semiconductor diode laser beam is demonstrated.     

A microcontinuum analysis of the self propulsion of the spermatozoa in the cervical canal

The hydrodynamics of the self propulsion of a spermatozoa, swimming through the mucus filling the cervical channel, is investigated. The mucus is modeled as a micropolar fluid and the spermatozoa as a 2-dimensional sheet swimming at low Reynolds number between two rigid walls. The wavelengths of the propulsive waves passing down the sheet are assumed to be very large compared to the channel spacing, but the amplitude of the propulsive waves is arbitrary. Expressions for the propulsive velocity and the energy expended by the swimming sheet are obtained in terms of various parameters involved. The results are elaborated through graphs. It is found that both the propulsive velocity and the rate of working by the sheet increase as the value of the micropolar parameters $\text{N}$ increases and that of $\text{L}$ decreases.     

Effect of ash on maximum thickness of plastic layer of coals

A study of the effect of ash yield on the maximum thickness of the plastic layer (MTPL) of some coking coals (as measured by the Sapozhnikov plastometer) has revealed that with an increase in the former the latter in general decre?es. A rectilinear relation approximately exists between the ash percentage (dry basis) and log MTPL values of coals. For the samples studied, a multiple correlation incorporating the rank factor was found to be unnecessary. Higher Fe₂O₃ and SO₃ contents from the coal were found to be associated with higher MTPL values.