Papers

This paper presents an analysis of capillary-tissue exchange system, representing blood by Casson fluid model flowing through a capillary of diameter 5 to 10 times larger than the red blood cells and the suspending medium plasma freely takes part in the exchange processes with surrounding tissue. Governing equations for continuity and momentum have been solved in the two regions (capillary and tissue) for fluid transport in capillary and the tissue subject to boundary and matching conditions at the capillary-tissue interface. The tissue has been identified as porous matrix following Darcy's law. Results for velocity profiles, pressure distributions in the two regions, wall shear stress and fluid flux at the interface have been represented through graphs and discussed. It has been noted that the capillary-tissue fluid exchange plays an important role in oxygen and nutritional transport to the tissue cells. Analysis oxygen transport is being presented in the next paper.

This work introduces a novel concept entitled "Center of concentration" which is similar to concepts in physics such as 'Center of gravity', and 'Center of mass'. It helps in a better understanding of the concentration of emissions from an assortment of stacks of varying heights and different pollutant emissions. Gaussian plume Dispersion Model is used in the study comprising of various Atmospheric stability Classes each of which representing a measure of turbulence in the ambient atmosphere. The effect of wind velocity is also studied. The proposed model helps in protecting and managing ambient air quality.

Hydrochemical investigations were carried out in and around Ambattur industrial area, Tamilnadu, India to assess the chemical composition of groundwater and its quality for drinking purpose. A total of 54 representative groundwater samples were collected from different wells to monitor the water chemistry of various ions. The type of water that predominated in the study area was assessed based on hydrochemical facies. Interpretation of analytical data shows that Na-Cl, Ca-Cl and mixed are the dominant hydrochemical facies in the study area. Alkali metals (Na⁺, K⁺ ) and strong acids (Cl^- , SO₄^2-) are dominating over alkaline earths (Ca²⁺, Mg²⁺) and weak acids (HCO₃^-, CO₃^2-). The mean concentration of the cations is in the order of Na⁺> Ca²⁺> Mg²⁺ >K⁺, while that for anions is Cl^- > HCO₃^- >SO₄^2-> NO₃^-. Statistical analyses indicate the highest positive correlation between EC and Cl with correlation coefficient of 0.97. Progressive reduction in correlation coefficient for EC with Na, TH and Mg are observed as 0.87, 0.84 and 0.77 respectively. Groundwater in the study area is generally hard, fresh to brackish and low in alkaline nature. The unsuitability of groundwater for drinking was identified in few places due to high total hardness and TDS. Fluoride is within permissible limit for human consumption as per international standards.

The current mirror is one of the basic building block in analog and mixed signal processing circuits. For high performance analog circuit applications the accuracy and output impedance are the most important parameters to determine the performance of the current mirror. This paper presents a new topology for a simple high performance current mirror for low voltage applications with high output impedance and large dynamic range. This topology is simulated in SPICE simulator for 0.13 micron CMOS technology.

Concrete is being extensively used in the construction industry. Though concrete has many advantages, it is brittle and therefore, a cause of concern in structures. Fracture is a problem that society has faced ever since the application of engineering techniques to structures. Recent advances in material technology further added more complexity to the problem. The behaviour of concrete can be understood by studying its fracture properties including crack propagation, size effect, work of fracture, Fracture energy (G_F) etc. Concepts of Linear Elastic Fracture Mechanics (LEFM) have been used to study the size effects of concrete. In this study, size effect law is presented. The fracture energy was predicted using Size effect law and Reunion Internationale des Laboratories et Experts des Materiaux, Systemes de construction et ourvrages (RILEM) recommendations on three-point bend (TPB) specimen. Size effect on the Strength of concrete beam has been observed. The parameter characteristic length (L_ch) was obtained along with G_F.

The present study focus on the structural and physical studies of chalcopyrite (CuFeS₂) samples in Laboratory. The sample has been characterized by X-ray diffraction technique and revealed that the sample is possesses tetragonal crystal structure with chalcopyrite structure and preferred orientation along (112) plane with the space group I 4 2d and point group 4 2m. The value of lattice parameter a and c for the sample is found to be 5.293 ºA and 10.423 ºA respectively. The d.c. electrical resistivity measurement have been carried out over temperature range of 300° to 800°K. The temperature dependence of electrical resistivity exhibited two activation energies. The magnetic susceptibility value is found to be 41.75 x 10^-8m³kg^-1 (S.I.unit). These values are compared with the standard data and showed that the sample is having tetragonal system structure, semiconductor behavior and paramagnetic which become ferromagnetic after applied external field.

This paper deals with the performance evaluation of a Shaping mill system involving four essential components viz. one main unit, two associate units and one independent unit. Only one repairman is used for repairing the failed components of all the units. Taking failure rates as exponential and arbitrary repair rates, various system effectiveness measures such as transition probabilities, mean time to system failure, availability, busy period of repairman are calculated. At last profit analysis is done on the basis of above measures.

Using Phillips and Van-Vechten (PVV) theory^1-3, the values of homopolar gap, ionic gap and Penn gap have been evaluated for A-C and B-C bonds in A^IIB^IVC₂^V ternary chalcopyrite semiconductors. Using the above parameters, the bond ionicity ( f_i ) has been determined. The values obtained are in good agreement with the literature value. The electronic polarizabilities have also been evaluated using the Clausius-Mossotti relation. The values are in good agreement with the ordinary sums of the polarizabilities of individual bonds.

Adiabatic and isothermal propagations of spherical shock waves produced due to a nuclear explosion have been studied using the energy hypothesis of Thomas in the nonuniform atmosophere of the earth. The explosion is considered at different height, is calculated shock strength and shock velocity for adiabatic and isothermal flow. It has been found that shock strength and shock velocity in isothermal flow is smaller in comparison to adiabatic flow. It has been also found that the energy of shock waves in adiabatic flow is larger than isothermal flow. The effect angular velocity of rotation on the shock velocity and shock strength is also discussed.

The study of thermopowers in metal has been the field of interest for the scientists since long. Mostly the convensional method for investigating the problem for thermopowers in metals are used. The presence of electric field alone the conductor results the electric current and the ratio of the current density to the electric field applied, in the absence of temperature gradient, defines the electrical conductivity of the metals considered. The presence of temperature gradient alone gives rise to the flow of heat. Further the discovery of electro-magnetic induction by Faraday suppressed the phenomena of thermoelectricity. The observed features of thermoelectric properties, reported in literature are very much complicated and anomalous. The standard theory generally fails to interpret them. These interpretations are also anomalous because they have no correlation among themselves. Moreover, they are unable to co-ordinate anomalous behaviors of other transport properties. In the present communication, an emphasis on the validity of free electron approximation in thermopowers in metals has been focused. The study also gives the qualitative picture of the various phenomenological behavior of free electron approximation in thermopowers in metal from thermo e.m.f.