Comminution by gyratory crusher is the first stage in the size reduction operation in mineral processing. In the copper industry, these machines are widely utilized, and their reliability has become a relevant aspect. In order to optimize the design and to improve the availability of gyratory crushers, it is necessary to calculate their power and torque accurately. The discrete element method (DEM) has been commonly used in several mining applications and is a powerful tool to predict the necessary power required in the operation of mining machines. In this paper, a DEM model was applied to a copper mining gyratory crusher to perform a comprehensive analysis of the loads in the mantle, the crushing torque, and crushing power. A novel polar representation of the radial forces is proposed that may help designers, engineers, and operators to recognize the distribution of force loads on the mantle in an easier and intuitive way. Simulations with different operational conditions are presented and validated through a comparison with nominal data. A calculation procedure for the crushing power of crushers is presented, and recommendations for the selection of the minimum resolved particle size are given.

The discrete element method (DEM) has been widely employed to model processes in different industries, such as mining, agriculture, pharmaceuticals, and food. One of the main lines of research, and in which different authors propose several approaches, is the calibration of parameters. Bulk calibration (BCA) is a common approach used that does not necessarily represent the individual behavior of each particle. On the other hand, direct measurement (DMA) is another approach employed in some cases. This work presents a comparison between calibration of DEM model parameters with non-cohesive spherical and polyhedral particles using a combination of direct measurement and bulk calibration. BCA is employed to calibrate friction parameters and DMA to characterize shape of the particles and coefficient of restitution of the contact between particles. Experimental data from Draw Down Tests are used to calibrate the friction parameters. Numerical optimization of the parameters is conducted by altering the coefficients of friction regarding the objective variables of mass flow, final mass, shear angle, and angle of repose. Quartz, granite, and coal are calibrated, obtaining good agreement with the experimental results. The influence of particle shape is tested, proving that more complex particles obtain better results for the analyzed case.

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The CO2 and water vapor exchange between leaf and atmosphere are relevant for plant physiology. This process is done through the stomata. These structures are fundamental in the study of plants since their properties are linked to the evolutionary process of the plant, as well as its environmental and phytohormonal conditions. Stomatal detection is a complex task due to the noise and morphology of the microscopic images. Although in recent years segmentation algorithms have been developed that automate this process, they all use techniques that explore chromatic characteristics. This research explores a unique feature in plants, which corresponds to the stomatal spatial distribution within the leaf structure. Unlike segmentation techniques based on deep learning tools, we emphasize the search for an optimal threshold level, so that a high percentage of stomata can be detected, independent of the size and shape of the stomata. This last feature has not been reported in the literature, except for those results of geometric structure formation in the salt formation and other biological formations.

In this study, we compare the scaling of waiting time distributions in Northern Chile Subduction context. For this, we analized 7-yr high spatial resolution and low complete- ness magnitude IPOC seismic catalog and 45-yr USGS catalog. A unified moment-epicentral area linear dimension-time scaling relation is empirically evaluated by calculating wait- ing times for different ranges of magnitude and epicentral area linear dimension and es- timating associated scaling coefficients, β analog to b-value and γ, the correlation frac- tal dimension. We find a scaling function that can be characterized with 3 distinct re- gions, regions whose behaviour depend on whether seismicity is in the coastal area or from intermediate depth. Moreover, high resolution localizations from IPOC catalog al- lows us to further observe differences in coastal seismicity, with lower plane seismicity behaviour alike intermediate depth. Thus, waiting time distribution primarily depends on whether seismicity is associated with subduction interface interaction or not, having respectively high/low correlated behaviour in the short scale region, non-exponential/exponential decay in the transition middle region and in all cases long-term clustering with a slower than exponential decay in the long scale.