América Berenice Morales-Díaz

Application of nanoelements in plant nutrition and its impact in ecosystems

Nanotechnology has great potential, as it can enhance the quality of life through its applications in various fields like agriculture and the food system. Around the world it has become the future of any nation. But we must be very careful with any new technology to be introduced regarding its possible unforeseen related risks that may come through its positive potential. However, it is also critical for the future of a nation to produce a trained future workforce in nanotechnology. In this process, to inform the public at large about its advantages is the first step; it will result in a tremendous increase in interest and new applications in all the domains will be discovered. With this idea, the present review has been written. There is great potential in nanoscience and technology in the provision of state-of-the-art solutions for various challenges faced by agriculture and society today and in the future. Climate change, urbanization, sustainable use of natural resources and environmental issues like runoff and accumulation of pesticides and fertilizers are the hot issues for today’s agriculture. This paper reviews some of the potential applications of nanotechnology in the field of agriculture and recommends many strategies for the advancement of scientific and technological knowledge currently being examined.

An online inertial sensor-guided motion control for tracking human arm movements by robots

We propose a simple and efficient online strategy based on inertial sensors to follow human arm movements in the task space by robotic platforms. The strategy is composed by the following ingredients: 2 inertial sensors attached to the human arm and forearm, the differential kinematics (DK) as well as the dynamic model of the corresponding robot and a motion control scheme. We use inertial sensors to obtain the orientation measurements of the human bodies in real-time. These body parameters together with the DK module allow us to map human hand trajectories into the joint space of the robot, where a standard PID control is implemented. Overall our strategy is able to transfer motion skills from human to a given robot by means of an online inertial sensor-guided motion control. Moreover, our method can be used for robot teleoperation applications in a master-slave configuration, with a human interface based on inertial sensors. We have successfully validated in simulations the effectiveness of the proposed strategy in a 2 degrees of freedom (dof) planar robot.

Hierarchical Task-Based Control of Multirobot Systems With Terminal Attractors

This brief proposes a hierarchical control scheme based on the definition of a set of multirobot task functions. To deal with the inherent conflicts between tasks, a strict hierarchy is imposed on them. We present a novel scheme that copes with two main difficulties shared in standard task-based controllers: 1) to impose a desired time convergence of tasks and 2) to avoid discontinuous task transitions occurred when a task is inserted or removed in the hierarchical structure. As a result, continuous input references are generated for the low-level control of the group. The validation is achieved in simulation and by performing an experiment with wheeled mobile robots.

INVENTORY REGULATION AND SYNCHRONIZATION OF DYNAMIC SUPPLY CHAINS BY NONLINEAR BOUNDED PI CONTROL

Abstract A nonlinear bounded PI control for inventory level regulation, and for production and incoming rate synchronization in linear dynamic supply chains is proposed. Control boundedness is required to satisfy physical and operational limitations. The control varies and synchronizes the production and incoming rates while regulating the inventory levels. The dynamic models allow reckoning multi-product and multi-purpose systems by considering production ratios. For regulation purposes, PI techniques are introduced via nominal references. A stability analysis based on linearization is performed. Simulations of a multi-product petrochemical company show the controller performance.

Macro-nutrient uptake dynamics in greenhouse tomato crop

ABSTRACT This study verified the concentration over time of nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur (N, P, K, Ca, Mg, and S) in the leaves, stems, fruits, and roots of tomato plants. An indeterminate growth variety with ball-type fruits suited for greenhouse cultivation was used. The results showed that the distribution of minerals in the different organs of the plant varies over time. The minerals N, P, and K showed a tendency to decrease their concentration, while the concentration of Ca and S increased and that of Mg remained constant over time. The leaves had the highest concentrations of N, P, K, Ca, and Mg. The concentrations of K, for both leaf and stem, ranged between 20 and 30 g kg−1. N and K were the most extracted minerals, while P was the least extracted mineral. The information presented in this paper allows a better fertilization plan for growing tomatoes inside greenhouses.

Testbed for modeling and inventory regulation of dynamic supply chains

There exist several ways to model supply chain systems, from discrete models to stochastic ones. Among them there is a modeling approach based on traffic flow theory which considers inventory levels and material flows. The resulting models are linear, although they are subject to constraints such as maximum production rates, as well as non negative inventory values and material flows. These constraints must be taken into account when designing a control strategy. In previous works of the authors a bounded PI control for inventory level regulation was introduced. The closed loop system was therefore a non liner one, due to the control boundaries. A stability analysis of the closed loop system based on linearization techniques was performed resulting in sufficient conditions for local asymptotic stability. Besides the theoretical framework the work was supported by numerical simulations on a petrochemical plant. In this work a testbed platform form by water tanks is developed. The systems allows applying the proposed modeling and control techniques, such that the experimental results agree with the simulated ones.

Dynamic Modeling of Silicon Bioavailability, Uptake, Transport, and Accumulation: Applicability in Improving the Nutritional Quality of Tomato

Silicon is an essential nutrient for humans, additionally is beneficial for terrestrial plants. In plants Si enhances tolerance to different types of stress; in humans, it improves the metabolism and increases the strength of skeletal and connective tissues as well as of the immune system. Most of the Si intake of humans come from edible plants creating a double benefit: first, because the absorption of Si increases the antioxidants and other phytochemicals in plants, thereby increasing its functional value, and second because the higher concentration of Si in plants increases intake in human consumers. Therefore, it is desirable to raise the availability of Si in the human diet through the agronomic management of Si accumulator species, such as corn, wheat, rice, soybeans, and beans. But also in such species as tomatoes, carrots, and other vegetables, whose per capita consumption has increased. However, there are few systematized recommendations for the application and management of Si fertilizers based on the physicochemical factors that determine their availability, absorption, transport, and deposition in cells and tissues. This study presents updated information about edaphic and plant factors, which determine the absorption, transport, and deposition rates in edible organs. The information was integrated into an estimated dynamic model that approximates the processes previously mentioned in a model that represents a tomato crop in soil and soilless conditions. In the model, on the other hand, was integrated the available information about key environmental factors related to Si absorption and mobilization, such as the temperature, pH, and soil organic matter. The output data of the model were compared against information collected in the literature, finding an adequate adjustment. The use of the model for educational or technical purposes, including the possibility of extending it to other horticultural crops, can increase the understanding of the agronomic management of Si in plants.

A satured control for a continuous anaerobic bioreactor

Abstract The quality and operational factors in a wastewater process define a bounded region. For this reason, a satured control that ensures the depollution of a wastewater bioreactor is presented. The control input is the dilution rate and the controllable variable is a linear combination of the substrate concentrations. Some results via simulation are presented.