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Start Over Topic business Topic 02 engineering and technology Publication Year Range Last 3 years Language portuguese
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1. Use and misuse of the Kubelka-Munk function to obtain the band gap energy from diffuse reflectance measurements

Author

Elisabete F. Freitas, Carlos J. Tavares, Mikhail Vasilevskiy, Iran Rocha Segundo, Joaquim A. O. Carneiro, Salmon Landi, and Universidade do Minho

Subjects
Materials science, Diffuse reflectance infrared fourier transform, Band gap, Tauc plot, 02 engineering and technology, Electron, Kubelka-Munk model, 01 natural sciences, 0103 physical sciences, Materials Chemistry, 010302 applied physics, Science & Technology, business.industry, General Chemistry, Function (mathematics), 021001 nanoscience & nanotechnology, Condensed Matter Physics, Amorphous solid, Computational physics, Semiconductor, Diffuse reflectance, Crystallite, Diffuse reflection, Band gap energy, 0210 nano-technology, business
Abstract

The determination of the optical band gap energy ( E g ) is important for optimization of the generation of electron/hole pairs in semiconductor materials under illumination. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) has been largely employed for the study of amorphous and polycrystalline materials. In this paper, the authors demonstrate, step by step, how to use the K-M function and apply it thoroughly to the determination of the E g of TiO2 semiconductor powder (pressed at different thicknesses) from diffuse reflectance spectroscopy (DRS) measurements. For the sample thicknesses 1–4 mm, E g values of 3.12–3.14 eV were obtained. With this work it is envisaged a clarification to the procedure of determination of the E g from the K-M theory and DRS data, since some drawbacks, and misconceptions have been identified in the recent literature. In particular, the widely used practice of determining the E g of a material directly from the K-M function is found to be inadequate.

Published
2022

2. The use of system dynamics on urban solid waste management: a literature analysis

Author

Gisele de Lorena Diniz Chaves, Renato Ribeiro Siman, and Larissa do Nascimento Sancheta

Subjects
Solid waste management, Process (engineering), Computer science, business.industry, Industrial engineering. Management engineering, Bibliographic review, 0211 other engineering and technologies, Complex system, 02 engineering and technology, Waste system, 010501 environmental sciences, System dynamics, T55.4-60.8, 01 natural sciences, Industrial and Manufacturing Engineering, Software, Risk analysis (engineering), 021108 energy, Urban solid waste, Business and International Management, business, 0105 earth and related environmental sciences
Abstract

Urban solid waste management is a complex system due to the many variables that compose it, which makes it difficult for managers to make decisions. Among the decision-making tools is system dynamics. To identify the gaps between the literature and the studies about urban solid waste management by using system dynamics method, a survey of published papers on the subject was made, which were later analyzed using some defined criteria, such as the level of the study, the software used for modeling, the variables included in the model, among others. The research identified that, among the stages of solid waste management, the collection process is still little incorporated in the models, being mentioned in only nine studies analyzed. Besides, the environmental, financial and institutional requirements were not adequately explored in the models. Future research should endeavor to include these elements in the models, which will allow the proposed system to be approximated to the complex reality of solid waste management.

Published
2021