A method to construct a family of strict Lyapunov functions, i.e., with negative definite derivative, for the super-twisting algorithm, without or with perturbations, is provided. This second order sliding modes algorithm is widely used to design controllers, observers and exact differentiators. The proposed Lyapunov functions ascertain finite time convergence, provide an estimate of the convergence time, and ensure the robustness of the finite-time or ultimate boundedness for a class of perturbations wider than the classical ones for this algorithm. Since the Lyapunov functions and their derivatives are quadratic forms, the operation with them is as simple as for linear time invariant systems.

In this paper a strong Lyapunov function is obtained, for the first time, for the super twisting algorithm, an important class of second order sliding modes (SOSM). This algorithm is widely used in the sliding modes literature to design controllers, observers and exact differentiators. The introduction of a Lyapunov function allows not only to study more deeply the known properties of finite time convergence and robustness to strong perturbations, but also to improve the performance by adding linear correction terms to the algorithm. These modification allows the system to deal with linearly growing perturbations, that are not endured by the basic super twisting algorithm. Moreover, the introduction of Lyapunov functions opens many new analysis and design tools to the higher order sliding modes research area.

This research aims to carry out a systematic review of the available literature about smart irrigation systems. It will be focused on systems using artificial intelligence techniques in urban and rural agriculture for soil crops to identify those that are currently being used or can be adapted to urban agriculture. To this end, a modified PRISMA 2020 method is applied, and three search equations are formulated. From those filters, and after a screening process, 170 articles are obtained. These articles are analyzed through VantagePoint, a text processing software. After this, they are taken through a detailed analysis phase in which 50 sources are selected as the most relevant to be read and analyzed by topic. Finally, the different phases of the analysis are used to draw conclusions that might be interesting for researchers working in this specific field or for the general public interested in rural and urban agriculture and its automation.

In this article, a new dissipativity based methodology to design observers for nonlinear systems is extended to cover systems with discontinuous and non monotone nonlinearities. A generalization and improvement of previous results for this class of systems is obtained. The class of systems covered are those in Lur'e form, with a LTI system in the feedforward and a discontinuous or multivalued nonlinearity in the feedback path

The vibration that occurs in vehicles during road transport has an important effect on the damage experienced by agricultural products, such as fruit. Young’s modulus and Poisson’s coefficient are critical mechanical properties of fruit, and alterations may indicate damage during transportation. This work studied the effect of vibration on mechanical damage in avocados (Persea americana Mill. cv. Hass) during a road trip of over 25 km in distance between the farm to avocado packing house. Chemical and mechanical properties were evaluated during twelve postharvest days at 23°C and 65% relative humidity. Once avocadoes reached full maturity, sensory tests were performed according to Colombian Technical Standards NTC 5328 and NTC 3932. Results obtained from field data are presented as power spectral density (PSD) functions to facilitate the interpretation of the exposure of produce to vibration energy during transportation. The highest intensity of these vibrations was recorded at a frequency of 2.5 Hz for frequency intervals of 0 Hz–5 Hz at the rear of the vehicle. The chemical analysis, includingmoisture content, protein, ash and ethereal extract, showed no statistically significant differences (p > .05) between the protected fruit (PF) and unprotected fruit (UF). The mechanical damage demonstrated a statistically significant difference (p < .05) in Young’s modulus between the PF and the UF. Sensory analysis also showed that the mechanical damage caused by the vibration levels affected the integrity of lenticels by means of the external appearance and pulp color descriptors of the fruit, which contributed to the subsequent darkening of the skin and the softening of the fruit.

The objective of this work is to find the most prevalent elements that have positive effects on pollinator density and diversity in crop fields, as reported in the literature, through a systematic review. The search equations yielded 659 papers, from which 138 were filtered and finally 55 were selected by publication date, journal, Scimago Journal Rank, Scimago Quartiles, subject area, keywords, and relevance. These papers were subjected to an in-depth qualitative analysis and tabulated using VantagePoint 10.0, finding 30 terms that were considered relevant due to their recurrence in all papers. From these 30 terms, the 10 most mentioned practices were extracted and grouped into four broad categories: proximity to natural habitats (98), grassland management (82), floral resources (80) and organic farming (65). All the above agricultural management practices were found to have the potential to increase pollinator numbers and diversity in different contexts. From the results, further research is recommended to try to attract the attention of specific groups of pollinators, as it was also identified that each species has very specific requirements, and a configuration intended just for one species could cause other groups to leave the area.