Complexes of Organic Arsonic Acids: Part VIII - Complexes of VO2+ & Cu2+ with Arylarsonic Acids

988-99

Complexes of Organic Arsonic Acids: Part IX - Complexes of Cr(III) & Co(II) with- Arylarsonic Acids

991-99

An experimental study of energy dependence of saturation thickness of multiply scattered gamma rays in zinc

The present measurements have been carried out to study the energy dependence of saturation thickness of multiply scattered gamma photons from zinc targets of various thicknesses. An inverse response matrix approach has been implemented to convert the observed pulse-height distribution of a NaI (Tl) scintillation detector to a photon spectrum and hence to improve the statistical error. These results in extractions of intensity distribution of multiply scattered events originating from interactions of 662 keV photon with thick target of zinc material. The observed pulse-height distributions are a composite of singly and multiply scattered events. To evaluate the contribution of multiply scattered events only, the spectrum of singly scattered events contributing to inelastic Compton peak has been reconstructed analytically. The scattered photons have been detected by a properly shielded NaI (Tl) gamma ray detector placed at different angle to the incident beam. The saturation thickness at which the number of multiply scattered events saturates has been measured. The signal-to-noise ratio and multiple scatter fractions have been found to be decreasing with increasing target thickness. The self-absorption correction factor improves the multiply scattered photon intensity but not the saturation thickness. The same experiment has been repeated with HPGe detector at 90° scattering angle. The results obtained with NaI (Tl) and HPGe detector show the same trend. The experimental results have been found to support the Monte Carlo calculations

Energy Dependence of Parameters Characterizing Multiply Backscattering of Gamma Photons

The present studies aimed to investigate the effects of energy dependence of parameters characterizing multiply backscattering of gamma photons. The numbers of multiply backscattered events are found to be increasing with thickness of copper target, and saturate for a particular thickness known as saturation thickness. The saturation thickness is found to be decreasing with increase in incident gamma photon energy, and also is not altered by the variation in collimator opening. The number, energy and dose albedos, characterizing the reflection probability of a material, are also evaluated. For each of the incident gamma photon energy, the number and energy albedos show an increase with increasing target thickness, and finally saturate. Monte Carlo calculations support the results of present experimental work

Effective Atomic Number Dependence of Radiological Parameters of Some Organic Compounds at 122 KeV Gamma Rays

Mass attenuation coefficient is a fundamental parameter of radiation interaction, from which the other radiological parameters like half Value Layer [HVL], tenth Value Layer [TVL], total atomic and electronic cross-sections, mass energy absorption coefficient, KERMA, CT number and effective atomic number are deduced. These parameters are extensively required in a number of fields such as diagnostic radiology, gamma ray spectroscopy, fluorescence analysis and reactor shielding. In the present work, mass attenuation coefficients are determined experimentally for some organic compounds at 122 keV incident photons using narrow-beam transmission geometry to establish a relation between effective atomic number (Zeff) and other deduced parameters. The experimental data for all these parameters are compared with the values deduced from WinXcom software package and are found to agree within experimental estimated errors. This study gives some insight about the photon interaction in some organic compounds whose effective atomic numbers match with some human body fluids

Solid Wastes Recyling through Sinter-Status at Tata Steel

Integrated steel plants generate several by-products rich in iron, flux and fuel values, categorised as waste. These by-products contain, besides mineral values, hazar-dous constituents causing damages to the environment. The environmental quality consciousness, the product cost competitiveness and high mineral values of these wastes have resulted in attempts to recyle these materials. Recycling recovers the mineral values, preserves the dec-reasing natural resources and deteriorating environment and eliminates the disposal cost. Sinter plant provides an avenue for recycling of these wastes. Recycling decreases the cost of sinter and hence the cost of steel produced. Present paper outlines the status of waste generation, their characteristics, and the quantity being recycled via the sinter plant at Tata Steel.Furthermore, it highlights the problems, which restricts its further recycling and discusses its influence on cost and quality of sinter

Improved crowd psychological model and control

The behavior of human crowd is an interesting phenomenon in which individuals are set as a collection that comprises of a highly dynamic social group. The crowd behaviors have been investigated by researchers over the years. Recent works include the study in modeling and controlling of the dynamic psychological behavior of crowds such as students’ behavior in a classroom or people’s behavior in a one-dimensional queue. In this paper, an improved version of the psychological crowd model has been proposed, where the social interaction between two individuals in a crowd is represented by a weightage, called the weight of social interaction. It has been shown that the inclusion of the social interaction weight has allowed social interactions between individuals to be included and results in a more accurate representation of the crowd’s psychological factors propagations. Since the psychological dynamics of crowd is naturally unstable, this paper also discusses the application of two nonlinear control approaches to stabilise the crowd to make it calm. Results show that for a crowd of n number of agents, the single-agent controller gives similar performance with the n-agent controller but with much less resources. The simulation results also show that it takes less amount of time to stabilise a crowd when the crowd model includes social interaction weights

Common Representation of Information Flows for Dynamic Coalitions

We propose a formal foundation for reasoning about access control policies within a Dynamic Coalition, defining an abstraction over existing access control models and providing mechanisms for translation of those models into information-flow domain. The abstracted information-flow domain model, called a Common Representation, can then be used for defining a way to control the evolution of Dynamic Coalitions with respect to information flow