OPTIMIZATION OF TUNED MASS DAMPER TO MINIMIZE THE DISPLACEMENT

Tuned mass dampers (TMDs) systems are one of the vibration controlled devices used to reduce the response of buildings subjected to lateral loadings such as wind and earthquake loadings. There has been many research of TMDs due to their simplicity. The optimization of properties of TMDs become one topic that will become the main topic in this research. The numerical optimization technique is used to compute the optimum values of TMD parameters that will minimize the maximum displacement of the structure. The concept of genetic algorithms is based on Charles Darwin’s theory of survival of the fittest. Genetic algorithm simulates the survival of the fittest among individuals over consecutive generation for solving a problem. The purpose of this research is to optimize the tuned mass damper parameter that are damping (kd) and damping system (cd). In this research a simple 20 stories building will be used for the simulations. The building is modeled as shear building. The TMDs will be added to the building in the top floor. In order to optimize the parameters of TMDs, Genetic algorithms (GAs) were used to help the optimization problems. For the comparison, different mass ratio with the range between 1% to 10% were us ed. The result of simulation shows that when mass ratio increased, frequency ratio will be decreased. When mass ratio increased, damping ratio of TMD will be increased. Then the building will be simulating subject earthquake ground accelerations such as El Centro 1940, Kobe 1995, Hachinohe 1968 and Northridge 1994 ground accelerations. The displacement of the structure without TMD in El Centro 1940, Kobe 1995, Hachinohe 1968 and Northridge 1994 ground accelerations are 0.244 m, 0.317 m, 0.312 m and 0.693 m, respectively. The acceleration of the structure without TMD are 6.545 m, 1.567 m, 4.31 m and 1.59 m, respectively. When applied with the 10% TMD, the displacement reduced by 18.95% to 0.198 m, 7.6 % to 0.293 m, 31.75% to 0.213 m and 20.10% to 0.554 m. For the acceleration reduced by 90% to 0.655 m, 90% to 0.157 m, 90% to 0.431 m, 90% to 0.159 m. The simulation of the optimized TMDs subject to earthquake ground accelerations show that the TMDs can reduce the displacement and acceleration of the building effectively

Industrial wind erosion: PM emission from the erodible flat surfaces of tailing basins

The article deals with the emission of Particulate Matter (PM) from the erodible surfaces of tailing basins. Dust emission from industrial sites typically derives from both conveyed sources and fugitive dust sources. While the emission from conveyed sources can be estimated with sufficient accuracy, the quantification of the emission rate from fugitive sources is notoriously more challenging, all the more so when the wind not only governs the dispersion phenomenon but also effects the emission rate (i.e.: erosion from erodible surfaces). The article specifically deals with the emission of PM from the deposits of mineralogical processing residue exposed to wind erosion (industrial win erosion). In fact, the exam of the technical and scientific reports has shown that the emission factors proposed for other types of erodible surfaces cannot be directly applied to those deposits, because of their peculiar characteristics: wide and flat surfaces with low roughness and residue physical state dependent on its moisture content. The object of the research hereby discussed is the definition of an emission conceptual model applicable to the Bauxite Residue Disposal Areas (BRDA). Basing on the analysis of the scientific literature regarding wind erosion, the article proposes a specific-site conceptual model and its validation procedure

Model simulations of dust sources and transport in the global atmosphere. Effects of soil erodibility and wind speed variability

Abstract. Global atmospheric dust is simulated using DEAD (Dust Entrainment and Deposition model) in combination with the global scale Oslo CTM2 using meteorological data for 1996. Dust sources are calculated both using mean wind speeds with model resolution (T63) and sub-grid wind speeds. Different datasets are used to describe soil erodibility. We explain how the different assumptions on dust production affect atmospheric dust burden and deposition. Some aspects of the annual dust cycle, such as the east Asian dust emissions are largely dependent on the data used to determine soil erodibility. Other aspects, such as the timing of the maximum in the African plume at Northern hemisphere summer is well modeled with all datasets applied here. We show that the daily variation in optical depth at Cape Verde at the west coast of Africa is well simulated when we assume that erodibility is correlated with surface reflectivity from MODIS satellite data. Using a sub-grid probability density function of wind speed to drive the dust sources facilitates dust emissions in areas with low wind speeds. Dust concentrations in remote areas are sensitive to the parameterization of wet deposition. Our results point out to need for a detailed soil erodibility dataset for global dust modeling, and they suggest that surface reflectivity is potentially valuable for producing or evaluating such datasets. 1