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Abstrak :
Synthesis and Monte Carlo simulation of improved concrete composites as x-ray/gamma ray shielding materials were performed. Samples of shieldings were synthesized using the base materials of Portland-type cement concrete with fillers of alloy steel, Co, Mn, and Cr, mixed separately as additives. The samples were characterized using Scanning Electron Microscopy-Energy Dispersive X-ray Spectrometry (SEM-EDS) to determine the constituent elements quantitatively. Linear attenuation coefficients of the samples were measured in the experiments and also simulated using Monte Carlo transport code MCNP5 in order to evaluate their shielding performance. The results of the experimentation and computer simulation reveal concrete with alloy steel added as having the best shielding properties, although concrete with other fillers added also exhibited enhanced shielding performance. It was demonstrated that 6.06 w% of fillers enhanced the x-ray/gamma ray shielding capability of ordinary concrete composites by improving their attenuation coefficient values by 40–60%.

Abstrak :
This book discusses the development, types and application principles of portable air purifiers in China. It analyzes the theoretical characteristics of air purifiers under various operational conditions, and points out that the term “Clean Air Delivery Rate” cannot be used to precisely reflect the problems that occur under various operational conditions. By comparing theoretical and measured data, it highlights the mainfeatures of air purifiers and key points in the design process for different applications. Calculation methods for the indoor particle concentration and the self-purification time are also provided. The book describes the conditions for window opening in smog and for selecting air purifiers, and proposes a newmethod for improvingtheir measurement. In closing, it includes a new assessment index.