http://nopr.niscair.res.in/handle/123456789/8816 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/9264 Title: Studies on 2,4,6-trinitrophloroglucinol (TNPG)—A novel flash sensitizer <br/> <br/>Authors: Mehilal; Sikder, N; Sikder, A K; Survase, D V; Agrawal, J P <br/> <br/>Abstract: 2,4,6-Trinitrophloroglucinol (TNPG), useful for percussion caps, detonator formulations and dye manufacture, has been synthesized with conventional nitrating agents under mild reaction conditions. The compound is characterized by IR, NMR, mass and elemental analyses. Further, the purity of the compound is confirmed by estimation of nitro groups. Thermal and explosive properties of TNPG have been investigated. The detonation velocity and detonation pressure are also estimated. <br/> <br/>Page(s): 59-62 Thu, 29 Jan 2004 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/9263 Title: Dielectric relaxation in glassy Se₉₀Ge_xIn_10-x <br/> <br/>Authors: Choudhary, N; Goel, D K; Kumar, A <br/> <br/>Abstract: Frequency and temperature dependence of dielectric constant (<b style=""><img src='/image/spc_char/italics_e.gif' border=0>'</b>) and dielectric loss (<b style=""><img src='/image/spc_char/italics_e.gif' border=0>''</b>) are studied in glassy Se₉₀Ge_xIn_10-x, where x = 0, 2, 4, 6, 8 and 10, in the frequency range 1-10 kHz and in the temperature range 293-400 K. The experimental results indicate that no dielectric dispersion exist in glassy Se₉₀Ge₁₀ alloy (x = 10). However, when In concentration increases (x = 8, 6, 4, 2 and 0), dielectric dispersion starts in the above frequency and temperature range. The values of <b style=""><img src='/image/spc_char/italics_e.gif' border=0>' </b>and <img src='/image/spc_char/italics_e.gif' border=0>'' at a particular temperature and frequency increase with the increase in In concentration. An analysis of the observed dielectric loss shows that the Guintini's theory of dielectric dispersion based on two electron hopping over a potential barrier is applicable in the present case. <br/> <br/>Page(s): 55-58 Thu, 29 Jan 2004 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/9262 Title: Compressive strength of lightweight aggregate concrete exposed to high temperatures <br/> <br/>Authors: Bingöl, A Ferhat; Gül, Rüstem <br/> <br/>Abstract: In this paper, effects of high temperatures on the compressive strength of concrete were investigated with the aim to produce a fire resistant concrete. Thus, the mixture groups were determined by replacing pumice for ordinary aggregate in the ratios of 25, 50, 75 and 100% in volume. The temperature values were chosen as 150, 300, 450, 600 and 750°C. The effects of heating duration over the compressive strength were also examined, and the different types of concrete mixtures were heated for one hour, three hours and five hours periods for each temperature values. It was observed that concrete properties were deteriorated at 150°C and the specimens began to lose some of their initial strengths at this temperature. Though a considerable strength lose was not seen between 150-300°C, all types of concrete mixtures continued to lose their compressive strength after 300°C. Every concrete mixture lost a significant part of their initial strength when the temperature is reached up to 750°C. When the lightweight aggregate ratio is increased for each temperature value, the loss of compressive strength of the concrete compared to the initial strength was decreased. It was found that the heating duration does not affect the strength loss significantly but a high temperature is a more significant parameter on the strength loss. <br/> <br/>Page(s): 68-72 Thu, 29 Jan 2004 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/9261 Title: Numerical solution of the flow of a second-order fluid under an enclosed rotating disc <br/> <br/>Authors: Sharma, H G; Biradar, K S <br/> <br/>Abstract: The solution of a non-linear boundary value problem arising due to the steady flow of an incompressible second-order fluid (flowing with a small mass rate of symmetrical radial outflow <i style="">m</i>, taken negative for a net radial inflow) under finite rotating disc (enclosed within a co-axial cylindrical casing) has been obtained numerically using finite difference method. The resulting equations are converted into a set of difference equations. Starting from the known values of flow functions for small values of the Reynolds number, the solution is extended for larger Reynolds number by making use of Newton-Raphson iterative method and Gauss elimination method. Effects of second order forces in the flow on the velocity field have been investigated in detail in the regions of recirculation and no-recirculation for the cases of radial outflow and inflow and illustrated graphically. Such flows are useful in mechanical and chemical industries. <br/> <br/>Page(s): 49-54 Thu, 29 Jan 2004 22:58:59 GMT