Kapil Agrawal | KIIT University (original) (raw)
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Papers by Kapil Agrawal
Mikrochimica Acta, 2004
A new simple flow injection analysis (FIA) procedure for the spectrophotometric determination of ... more A new simple flow injection analysis (FIA) procedure for the spectrophotometric determination of cationic surfactants (CSs), i.e. dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB), and cetylpyridinium chloride (CPC), is described. The method is based on absorptivity enhancement of the Bi(III)-I− complex in the presence of CSs. Among the investigated compounds, highest sensitivity is obtained with CPC, so it was selected for detailed study. The apparent value of molar absorptivity of the complex in terms of CPC is (6.00)×103 L mol−1 cm−1 at λmax 505 nm for FIA determination. The detection limit (3σ criterion) of the method for FIA determination is 110 µg L−1. The sample throughput is >140 samples h−1. The effect of analytical and FIA variables in the determination of CPC is described. The composition of the complex is discussed. The method is free from interferences of common ions. The method has been applied to the analysis of surfactant contamination in environmental samples, i.e. pond water, municipal/industrial wastewater, sewage, sediment and soil.
In the realm of computational finance, the performance of the optimal portfolio largely depends u... more In the realm of computational finance, the performance of the optimal portfolio largely depends upon its composition and its ability to accurately predict the market movements. Recent empirical studies have shown that the underlying assumption of normality of asset returns for risk modeling is seriously flawed, in view of their asymmetric and fat-tailed behavior. This problem is further aggravated when
Journal of Fluid Mechanics, 2001
Meso-scale structures that take the form of clusters and streamers are commonly observed in dilut... more Meso-scale structures that take the form of clusters and streamers are commonly observed in dilute gas-particle flows, such as those encountered in risers. Continuum equations for gas-particle flows, coupled with constitutive equations for particle-phase stress deduced from kinetic theory of granular materials, can capture the formation of such meso-scale structures. These structures arise as a result of an inertial instability associated with the relative motion between the gas and particle phases, and an instability due to damping of the fluctuating motion of particles by the interstitial fluid and inelastic collisions between particles. It is demonstrated that the mesoscale structures are too small, and hence too expensive, to be resolved completely in simulation of gas-particle flows in large process vessels. At the same time, failure to resolve completely the meso-scale structures in a simulation leads to grossly inaccurate estimates of inter-phase drag, production/dissipation of pseudo-thermal energy associated with particle fluctuations, the effective particle-phase pressure and the effective viscosities. It is established that coarse-grid simulation of gas-particle flows must include sub-grid models, to account for the effects of the unresolved mesoscale structures. An approach to developing a plausible sub-grid model is proposed.
Journal of Fluid Mechanics, 1999
... However, the various models for the boundary interactions yield the same qualitative behaviou... more ... However, the various models for the boundary interactions yield the same qualitative behaviour. ... Effect of boundaries on plane Couette flow of granular material ... adiabatic case (ϵ = 0) to the Johnson & Jackson boundary conditions (ϵ = 1). The solutions for intermediate values of ...
Mikrochimica Acta, 2004
A new simple flow injection analysis (FIA) procedure for the spectrophotometric determination of ... more A new simple flow injection analysis (FIA) procedure for the spectrophotometric determination of cationic surfactants (CSs), i.e. dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB), and cetylpyridinium chloride (CPC), is described. The method is based on absorptivity enhancement of the Bi(III)-I− complex in the presence of CSs. Among the investigated compounds, highest sensitivity is obtained with CPC, so it was selected for detailed study. The apparent value of molar absorptivity of the complex in terms of CPC is (6.00)×103 L mol−1 cm−1 at λmax 505 nm for FIA determination. The detection limit (3σ criterion) of the method for FIA determination is 110 µg L−1. The sample throughput is >140 samples h−1. The effect of analytical and FIA variables in the determination of CPC is described. The composition of the complex is discussed. The method is free from interferences of common ions. The method has been applied to the analysis of surfactant contamination in environmental samples, i.e. pond water, municipal/industrial wastewater, sewage, sediment and soil.
In the realm of computational finance, the performance of the optimal portfolio largely depends u... more In the realm of computational finance, the performance of the optimal portfolio largely depends upon its composition and its ability to accurately predict the market movements. Recent empirical studies have shown that the underlying assumption of normality of asset returns for risk modeling is seriously flawed, in view of their asymmetric and fat-tailed behavior. This problem is further aggravated when
Journal of Fluid Mechanics, 2001
Meso-scale structures that take the form of clusters and streamers are commonly observed in dilut... more Meso-scale structures that take the form of clusters and streamers are commonly observed in dilute gas-particle flows, such as those encountered in risers. Continuum equations for gas-particle flows, coupled with constitutive equations for particle-phase stress deduced from kinetic theory of granular materials, can capture the formation of such meso-scale structures. These structures arise as a result of an inertial instability associated with the relative motion between the gas and particle phases, and an instability due to damping of the fluctuating motion of particles by the interstitial fluid and inelastic collisions between particles. It is demonstrated that the mesoscale structures are too small, and hence too expensive, to be resolved completely in simulation of gas-particle flows in large process vessels. At the same time, failure to resolve completely the meso-scale structures in a simulation leads to grossly inaccurate estimates of inter-phase drag, production/dissipation of pseudo-thermal energy associated with particle fluctuations, the effective particle-phase pressure and the effective viscosities. It is established that coarse-grid simulation of gas-particle flows must include sub-grid models, to account for the effects of the unresolved mesoscale structures. An approach to developing a plausible sub-grid model is proposed.
Journal of Fluid Mechanics, 1999
... However, the various models for the boundary interactions yield the same qualitative behaviou... more ... However, the various models for the boundary interactions yield the same qualitative behaviour. ... Effect of boundaries on plane Couette flow of granular material ... adiabatic case (ϵ = 0) to the Johnson & Jackson boundary conditions (ϵ = 1). The solutions for intermediate values of ...