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The mechanical properties of agricultural materials influence not only the loads occurring inside agricultural silos, but also the design of several types of post-harvest machinery. The loads generated by these materials inside silos can be predicted with silo calculation methodologies from their mechanical properties. It has been known for many years that these properties are highly dependent on the moisture content of the material. However, to date, there are not many studies focused on its determination. The goal of this research is the determination of the internal friction angle, apparent cohesion, angle of dilatancy and apparent specific weight of maize when different moisture contents are applied. The equipment used for this study consisted mainly of direct shear and oedometer assay apparatus. The maize samples used were moistened using a climatic chamber. Moisture contents applied to maize samples ranged from 9.3% to 17.4%. Results similar to those provided by other authors were obtained for the internal friction angle, apparent cohesion and apparent specific weight. On the other hand, the values obtained for the dilatancy angle of maize as a function of moisture content could not be compared because nothing has been published so far. The values obtained for this parameter overlap with those published for this material under ambient conditions. In addition, for the samples tested, these results did not allow confirming the existence of a direct relationship between the dilatancy angle and the moisture content. Finally, the increase in moisture content led to an increase in apparent specific weight, which differed from that published in the literature. The values provided here can be used for the optimization of storage and handling structures for granular agricultural materials.

The loads generated inside agricultural silos under static and dynamic conditions depend on the mechanical properties of the materials stored inside them. Silo calculation methodologies are based on these mechanical properties. Although it is known that moisture content greatly influences the values reached by these mechanical properties, only a few studies have been conducted to determine them. The present work determines the angle of internal friction, the apparent cohesion, the dilatancy angle and the apparent specific weight of wheat when subjected to different moisture contents. Direct shear and oedometer assay devices were used. In addition, a climatic chamber was used to moisten the wheat samples used in this work. From the different assays conducted, it could be observed that the values of the angle of internal friction, the apparent cohesion and the apparent specific weight were like those found in the literature. However, no values of the dilatancy angle of wheat as influenced by moisture content were previously reported. The values obtained here for this parameter are within the range of those specified for dry wheat samples. Finally, higher apparent specific weight values were observed as moisture content increased up to 13.4%, then decreasing at a moisture content of 15.5%. This was not expected according to the results stated by some authors, although others reported a similar tendency. The values here provided can be used in silo load calculations involving numerical methods for modeling technological processes.

This paper addresses the lack of attention paid by the scientific community to the optimization of timber structures, specifically in the context of large-span agro-industrial constructions. The study focuses on the optimization of a three-dimensional roof composed of GL32h glulam regular double-tapered beams and purlins. Firstly, MATLAB was employed to develop a calculation software and then run the proposed optimization model based on genetic algorithms, in order to optimize the different geometries of the construction elements based on cost, as well as the optimum arrangement of the purlins and the number of beams. Moreover, statistical analyses were carried out on more than 200 optimization data points to uncover the influence of different variables in the optimization process. It was found that the snow load and span have a significant influence on the prediction of the height and width of beams and purlins, as well as the purlin spacing; while, as expected, the roof length also influences the optimal number of beams. All these findings could promote the use of timber structures; thus, achieving more sustainable and efficient construction practices.

Photosensitivity is a neurological disorder in which a person’s brain produces epileptic discharges, known as Photoparoxysmal Responses (PPRs), when it receives certain visual stimuli. The current standardized diagnosis process used in hospitals consists of submitting the subject to the Intermittent Photic Stimulation process and attempting to trigger these phenomena. The brain activity is measured by an Electroencephalogram (EEG), and the clinical specialists manually look for the PPRs that were provoked during the session. Due to the nature of this disorder, long EEG recordings may contain very few PPR segments, meaning that a highly imbalanced dataset is available. To tackle this problem, this research focused on applying Data Augmentation (DA) to create synthetic PPR segments from the real ones, improving the balance of the dataset and, thus, the global performance of the Machine Learning techniques applied for automatic PPR detection. K-Nearest Neighbors and a One-Hidden-Dense-Layer Neural Network were employed to evaluate the performance of this DA stage. The results showed that DA is able to improve the models, making them more robust and more able to generalize. A comparison with the results obtained from a previous experiment also showed a performance improvement of around 20% for the Accuracy and Specificity measurements without Sensitivity suffering any losses. This project is currently being carried out with subjects at Burgos University Hospital, Spain.

Greenhouses are employed worldwide to protect crops from meteorological conditions as well as to control some plant production variables. As multi-tunnel structures are amongst the most used, in this article, we focus on cost optimization of both the steel structure and the concrete foundation of this greenhouse typology. Firstly, three structural alternatives composed of three tunnels and differentiated portal frames were dimensioned conforming to the European design of steel structures, namely, Eurocode 3; meanwhile, the foundation was calculated through a previously validated matrix method. Then, genetic algorithms were employed to optimize for cost each proposed design and to evaluate the relative weight of each element in the overall steel consumption. Moreover, the influence of the greenhouse design on the final cost was also assessed, and it was found that the most cost-effective solution corresponded to the optimized greenhouse alternative exhibiting a 3.5 m separation between portal frames and the combination of a steel profile and plastic gutter (i.e., M3OPT at 15.14 €/m2). Finally, from the study on the influence of the portal frame separation, a further cost per square meter reduction was found for a design with the so-called structural gutter (i.e., steel profile and plastic water collection system) as support for the arches and a 4.5 m separation at 14.21 €/m2.

This study focuses on the friction characteristics of chestnut sawn timber (Castanea sativa Mill.) of Spanish origin. The values of both the static and dynamic friction coefficients were determined, as this knowledge is of interest for the numerical simulation of the stress transmission in joints of timber structures. Therefore, two sets of tests were carried out combining different orthotropic orientations. Firstly, timber-to-timber tests were assessed to obtain the coefficients applicable to carpentry joints; secondly, timber-to-steel friction was also evaluated to determine the coefficients needed for mechanical joints with metal plates and dowels. The results presented a conventional behavior of friction, i.e., a maximum static value before sliding and a subsequent decrease. For timber-to-timber tests, global mean values of μs = 0.47 and μk = 0.36 were found, and the results were slightly higher than those obtained between pieces with the same orthotropic orientation and sliding direction. Regarding timber-to-steel tests, the resulting friction coefficients, as well as the difference existing between the static and dynamic values were lower (μs = 0.19 and μk = 0.17) compared to the timber-to-timber sets. The use of these results in numerical studies would allow for closer simulations in which chestnut wood is involved in friction. In addition, the values provided herein could be included as new data in standards that already consider other wood species.

The mechanical properties of the materials stored in agricultural silos determine the loads they generate under static and dynamic conditions. The present work describes the mechanical properties of wheat, maize and wood pellets. Direct shear and triaxial assay devices, and oedometers (all commonly used in geotechnical assays), were used to determine these materials’ internal angle of friction, Poisson’s ratio, Young’s modulus, apparent specific weight, etc. The results for wheat and maize were similar to those previously reported by other authors. For the wood pellets, the results for the internal angle of friction and apparent specific weight were also similar to those found in the literature. However, this is a relatively new type of material, and few results of this type have been reported, certainly not enough for reference values to be available. This work is the first to report this material’s dilatancy angle and Poisson’s ratio. A table is provided with suggested reference values for the studied mechanical properties of each of the test materials; these can be used in silo load calculations involving numerical methods.