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This study comprehensively examines the techno-economic potential of utilizing offshore wind resources for hydrogen production in Mexico. Through the integration of geospatial analysis techniques with energy generation and economic models, the research estimates hydrogen production, CO 2 eq emissions reduction potential, Levelized cost of electricity (LCOE), and Levelized cost of hydrogen (LCOH). The analysis highlights Mexico's capacity to produce up to 217.33 million tons of hydrogen annually, predominantly from the Gulf of Mexico. Centralized offshore hydrogen production demonstrates significant cost advantages, being up to 0.92 USD/kg cheaper than onshore production. The study also underscores the economic benefits of repurposing existing oil and gas infrastructure, which can reduce LCOH by up to 11%. Environmental benefits are substantial, with hydrogen use in ammonia production potentially reducing CO 2 eq emissions by 82.5%. Additionally, the study identifies highly suitable offshore areas for hydrogen production, particularly near existing oil infrastructure, facilitating the integration of new renewable energy projects with minimal additional infrastructure development. These findings provide valuable insights for policymakers and stakeholders, emphasizing the economic viability and environmental benefits of offshore wind hydrogen production as a strategic pathway for Mexico's energy transition and decarbonization efforts. [Display omitted] • Mexico can produce 217.33 MTon/year of hydrogen, 78.8% from the Gulf. • Transmitting energy offshore and then producing H 2 is up to 0.92 USD/kg cheaper. • Repurposing offshore oil infrastructure reduces LCOH by up to 11%. • 40% of offshore areas, near oil infrastructure, are ideal for hydrogen production. • 82.5% of CO 2 eq emissions in ammonia production could be reduced. [ABSTRACT FROM AUTHOR]

Many efforts have been made to assess the potential of green hydrogen production at global, regional, and national levels using Geographic Information Systems (GIS); however, many dismiss the possibility of producing hydrogen in urban settlements. In order to reveal the true potential of these areas, it is essential to provide arguments that allow evaluation of the feasibility of promoting and impulsing the concept of hydrogen cities. Based on this idea, this work assesses the monthly and annual potential of solar hydrogen in urban areas of Mexico using actual measurements of sunshine duration as electrolyzer production times. Moreover, as light transportation is crucial for cities, we examine the substitution of gasoline with hydrogen and its cost throughout the year. These constitute the main contribution of the present work. This study departs from the geographical and technical potential of solar energy, and by using GIS, the amount of hydrogen production per unit of area (Ton/(km2 year)) was computed. The levelized cost of hydrogen production (LCOH) is also evaluated, using two of the most popular and commercial electrolysis technologies: PEM and Alkaline. Our results revealed that Mexican urban areas have a high potential to produce solar hydrogen, having an average annual production that varies from 1991.8 Ton/km2 to 4338.3 Ton/km2 according to the region. The total solar hydrogen potential of all Mexican urban places is 9.39 MTon/year, which could satisfy up to 42.6 times the 2020 hydrogen demand of Mexico. We found that the national gasoline consumption could be replaced by H 2 , requiring between 42% and 52% of the total urban production. Additionally, the national average of LCOH was found to be about 6.25 USD/kg for alkaline electrolyzer and 9.50 USD/kg for PEM technology, considering the yearly average sunshine duration of 3237 h/year, which means that Mexico could be competitive at large-scale hydrogen production by using Alkaline technology. Our findings have the potential to impact positively on the country since they provide information to facilitate the derivation of public policies from a rigorous and technical perspective. [Display omitted] • Urban hydrogen potential could satisfy up to 42.6 times the 2020 Mexico's hydrogen demand. • Light transportation would require between 46.1% and 54.7% of the total hydrogen produced. • Spring and summer had the largest production, between 0.52 MTon/month and 0.81 MTon/month. • LCOH was estimated to be between 6.25 USD/kg and 9.50 USD/kg for Alkaline and PEM technologies. • Alkaline electrolyzers resulted in a more feasible technology in the short term. [ABSTRACT FROM AUTHOR]

The effect of the energy interchange dynamics on the Zero-Energy Hydrogen Economy (ZEH2E) of households with Fuel-cell Hybrid Electric Vehicles (FCHEV) is investigated in this work. An isolated grid constituted of a household, a battery bank, a PEMFC, a PEM electrolyzer, and PV panels were used as a rig for the study together with an optimal energy management strategy, which guaranteed ≥100% PV self-sufficiency index of the household load and hydrogen harvesting for electrical transportation. Global horizontal irradiance and temperature data, measured every 10 min for 365 days in three different locations of Mexico and Hardware-in-the-loop experiments were used in the analysis. Short and long-term effects of the energy storage system and their importance for achieving ZEH2E conditions were identified. Proposed solar, and battery utilization indexes revealed the short-term effect of the battery storage, imperceptible even in daily average values. Hydrogen production and vehicle autonomy values strongly depended on the season of the year, location, vehicle characteristics, driving cycle, and household load, therefore two indexes were proposed to compare the different scenarios: the hydrogen production-to - average household power load ratio (m H 2 -to-load) and the average vehicle power per traveled distance. These indexes allowed us to reveal low effective load-location pairs for hydrogen production and low effective driving cycle-vehicle pairs for hydrogen utilization. Our results revealed that the average data to analyze ZEH2E conditions is not enough and that detailed data is necessary. [Display omitted] • The effect of the energy dynamics on ZEH2E of households with FCHEV is studied. • Hardware-in-the-Loop experiments as well as real solar irradiance and temperature data are used. • 3 locations, 2 household electric load profiles, 4 vehicle types are tested. • Proposed indexes revealed short-term and long-term actions of the energy sources. • 0.36–1 g of H 2 per load power were found and autonomy values from 52 to 116 km per day. [ABSTRACT FROM AUTHOR]

Abstract The problem of optimal power management for uncertain off-grid hybrid systems is studied in this paper. A suitable parametrization of the energy sources and sinks is used to obtain a graphical representation of the feasible set along with a direct observation of the solution and its piecewise description. The proposed approach pretends to clarify how the optimal solution migrates from the use of one source to another as the solar radiation changes and how the dynamic response of the sources restrict the feasible set. A power generation system (PGS) is used to study the limitations that the sun power variability and the parametric uncertainty impose on the optimality; being the PGS constituted by photovoltaic (PV) panels, a fuel cell (FC), an electrolyzer (E) and a battery bank. A simple optimal Power Management Strategy (PMS) is proposed as a result of the analysis and its performance is illustrated in a telecom facility for three different locations in Mexico. Results are shown indicating the viability of the strategy for highly variable environments. Highlights • A graphical approach for optimal power management is proposed. • A parametrization is used to allow simplification of the optimization problem. • The case of parameter uncertainty in the power hybrid system is analyzed. • Results demonstrate that optimal operation is possible in presence of uncertainty. [ABSTRACT FROM AUTHOR]

This paper introduces a means to evaluate the severity of the lateral skid phenomenon based on a balance of forces applied to the vehicle. Derived from this analysis, a lateral Skid Index (SI) is proposed which, along with the well-known rollover index, is used to monitor the vehicle and to derive an indirect envelope specification. A robust control ensures the accident risk mitigation in spite of model uncertainty and perturbations from the driver. Speed and predictive dependent risk switching criteria are used to activate the control action. The proposed strategy is illustrated using Hardware-in-the-Loop experiments and its comparison with existing strategies is performed. [ABSTRACT FROM AUTHOR]

The Opuntia genus, whose origin is in Mexico where several species grow wild, is taxonomically diverse and has become an important crop worldwide. The aim of this work was to assess the molecular composition of five Opuntia species and three different varieties of each taxonomically identified species with different domestication gradients (from the wildest to the most domesticated O. ficus-indica ). Data were subjected to chemometric evaluation using principal component analysis (PCA), which showed that O. ficus-indica seems to fall far outside of the current domestication gradient that has been proposed, and its ancestor is still unclear. Phenolic compounds showed major (eucomic acid, kaempferol 3-O-robinobioside-7-O-arabinofuranoside, isorhamnetin 3-O-galactoside, and isorhamnetin 3-O-rhamnoside-7-O-(rhamnosyl-hexoside)) and minor compounds that were present only in wild (kaempferol 3-O-arabinofuranoside) or domesticated (quercetin 3-O-rhamnosyl-(1→2)-[rhamnosyl-(1→6)]-glucoside) species. This information could be very useful for authentication of Opuntia species and the identification of species with the highest potential as sources of compounds with nutritional and therapeutic properties. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the limitations that impose the presence of uncertainty in the design of optimal energy management strategies (EMSs) for fuel cell (FC) hybrid electric vehicles. Using an electric powertrain constituted by a hydrogen FC and a battery bank, the fuel consumption minimization problem is analyzed in the presence of parametric uncertainty. The conditions that ensure that the nominal optimization problem matches the solution of the real (unknown) optimization problem are clearly stated. By observing that the uncertainty will limit the feasible solutions of the minimization consumption problem, supervisory control constituted by heuristic rules is proposed to face such limitations, resulting in a mixed optimal–heuristic EMS. The effect of the powertrain design, driving cycle, and initial conditions in the proposed strategy is discussed. Numerical simulations provide evidence of the advantages and features of the supervisory control strategy. [ABSTRACT FROM PUBLISHER]

The main goal of this work is to study the stability properties of an aircraft with nonlinear behavior, controlled using a gain scheduled approach. An output feedback is proposed which is able to guarantee asymptotical stability of the task-coordinates origin and safety of the operation in the entire flight envelope. The results are derived using theory of hybrid and singular perturbed systems. It is demonstrated that both body velocity and orientation asymptotic tracking can be obtained in spite of nonlinearities and uncertainty. The results are illustrated using numerical simulations in F16 jet. [ABSTRACT FROM AUTHOR]

The aim of this paper is to propose a differential braking rollover mitigation strategy for wheeled vehicles. The strategy makes use of a polytopic (piecewise linear) description of the vehicle and includes translational and rotational dynamics, as well as suspension effects. The braking controller is robust and the system states are predicted to estimate the rollover risk up to a given time horizon. In contrast to existing works, the switched predictive nature of the control allows it to be applied only when risk of rollover is foreseen, interfering a minimum with driver's actions. The stability of the strategy is analyzed and its robustness is illustrated via numerical simulations using CarSim for a variety of vehicles. [ABSTRACT FROM AUTHOR]

SUMMARY In this work, a class of switching systems known as integrator is studied. Such systems have the feature of being very simple and allow us to gain insight on the effect that the switching sequence has on system stability. Three problems are analyzed. First, the practical stabilizability problem under system uncertainty is studied. Confinement regions are explicitly computed, and switching sequences based on the nominal behavior of the systems are derived. Second, the practical stabilizability problem using output feedback is solved; in this case, sufficient conditions are proposed. Finally, by joining both results, sufficient conditions for practical stabilizability of uncertain systems under output feedback are given. The results are illustrated with examples and some extensions for uncertain linear system and event-based switching are given. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the geometry and operation of membraneless laminar flow-based fuel-cells (LFFC) is analyzed. Three different fuel cell geometries are studied, these are: the conventional rectangular cell, a cylindrical cell and a star shaped cell. The geometries are derived from the principle of design of increasing the effective area of cathode while conserving the same volume-to-length ratio. Since the mixing and depletion widths are major factors that determine the cell performance, maximum Reynolds and Péclet numbers as well as fuel utilization are considered as variables of comparison. Furthermore, electrical characteristics as current density and total extracted current have been considered as well. Using finite element simulations, it is shown that for a HCOOH−O2 cell, improved fuel utilization of 89% and 68.2% can be obtained with star and cylindrical geometries respectively, in comparison to conventional rectangular geometry (42.4%). Moreover, the total extracted current is also improved, reaching percentages greater than 1200% and 400% for the star and cylindrical designs respectively. It is shown that moving liquid–liquid interface, it is possible to further increase the current density of the designs and therefore the total extracted current. [Copyright &y& Elsevier]

In this study, a robust current switching control of converters is proposed. It is proved that the controller is able to guarantee global current regulation, as well as the maximum voltage and current ripple, simultaneously. Such features make it ideal for implementing power-management strategies and to be used along fuel cells. The control scheme is shown to be robust against model uncertainty and since it is based on the piece-continuous model instead of average models, it is suitable for operation under a wide range of conditions. Moreover, its complexity does not increase with the number of cells. Experimental evidence of the advantages and features of the proposed control is presented in a two-cell boost converter. [ABSTRACT FROM AUTHOR]

In this study, a robust current switching control of converters is proposed. It is proved that the controller is able to guarantee global current regulation, as well as the maximum voltage and current ripple, simultaneously. Such features make it ideal for implementing power‐management strategies and to be used along fuel cells. The control scheme is shown to be robust against model uncertainty and since it is based on the piece‐continuous model instead of average models, it is suitable for operation under a wide range of conditions. Moreover, its complexity does not increase with the number of cells. Experimental evidence of the advantages and features of the proposed control is presented in a two‐cell boost converter. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a coordinated guidance-tracking hybrid controller in order to control velocity and attitude of fixed wing aircrafts. The proposed controller is able to adapt its operation depending on the trajectory, altitude and model uncertainties. The adaptive mechanism is activated via the satisfaction of a set of prescribed restrictions which are both security and performance based. The nature of the controller is hybrid because the system dynamics is modeled continuously with the interaction of an adaptive discrete control action which defines the next active behavior of aircraft. Here, conditions of stability are studied as well as their dependence with control gains, control bounds, and switching restrictions. Numerical simulations in a F16 aircraft are used for illustrating the proposed control method. [ABSTRACT FROM AUTHOR]

The use of an electric differential (ED) constitutes a technological advance in vehicle design along the concept of more electric vehicles (MEVs). EDs have the advantage of replacing loose and heavy mechanical differentials and transmissions with lighter and smaller electric motors directly coupled to the wheels via a single gear or an in-wheel motor. To date, EDs have been proposed for two- and four-wheeled vehicles. Despite its long reported success and possible advantages in terms of flexibility and direct torque control of the wheels during cornering and risky maneuvers, the ED has several problems that have limited its applicability, for instance, an increment of control loops and an increase of computational effort. Therefore, the main purpose of this paper is to present a simple and easy-to-implement ED that ensures both reliability and good path tracking. The proposed strategy has the advantage of being linear and, therefore, easy to implement. Furthermore, a rigorous proof of stability is presented, and connections with other controllers are discussed. Features and advantages of the proposed scheme are illustrated via numerical simulations in a 4-kW system, which is able to handle 500-kg mass and deliver peak power up to 10 kW during transit periods. [ABSTRACT FROM AUTHOR]

Abstract: An excitation controller for a single generator based on modern multi-loop design methodology is presented in this paper. The proposed controller consists of two-loops: a stabilizing (damping injection) loop and a voltage regulating loop. The task of the stabilizing loop is to add damping in the face of voltage oscillations. The voltage regulating loop is basically a PI compensator whose objective is to obtain terminal voltage regulation about the prescribed reference. The main contribution of this paper is to give some insights into the systematic derivation of multi-loop controllers of power generators. Certain connections between the two-loop excitation controller and standard PSS–AVR schemes are discussed. In this way, some insight into the stability of the standard PSS scheme is obtained from the analysis of the proposed controller. The proposed controller is evaluated via numerical simulations on a full finite-element model. [Copyright &y& Elsevier]

This letter uses a singular perturbation method to introduce a double-scroll version of the Rossler system. Its generation and basic dynamic behavior are briefly described. [ABSTRACT FROM AUTHOR]

The problem of stabilizing the Chua circuit about equilibrium points is addressed in this paper. Singular perturbation methods are used to prove that semiglobal stabilization of the circuit trajectories about equilibrium points can be achieved by means of current damping injection in a single circuit node. It is shown that such damping injection can be implemented with a standard high-pass filter. In this way, the resulting feedback control strategy has interesting robustness features since an a priori knowledge of the circuit equilibrium points is not required. Experimental work is used to illustrate the control performance. [ABSTRACT FROM AUTHOR]

Presents a study examined the stability of linear multiloop control of quasiresonant converters (QRC). Modelling and problem formulation; Main results; Illustrative example.

Presents a study which discussed the stability of boost and buck-boost direct current-direct current power converters under proportional plus integral control. Approaches to control switching regulators: Results; Conclusions.

The aim of this letter is to improve operation of a class of resonant converters and take quasi-resonant converters (QRCs) as a benchmark to realize this aim. In particular, a variable pulsewidth control scheme is proposed that ensures soft-switching conditions and reduces conduction losses. The control scheme has the feature of significant improvement of efficiency and wider voltage conversion ratio. The proposed controller modifies the pulsewidth of the square driving signal without modifying its frequency. This fact makes it able to be used as a complementary control action to voltage regulators. Results are illustrated via experimental work for the case of a boost-type zero-voltage-switching QRC. [ABSTRACT FROM AUTHOR]

A sample-data modeling strategy for a 30-kW, two-phase dual interleaved buck–boost converter with peak current control is analyzed in this article. A small-signal converter model is derived to characterize the system utilizing the current peaks of the two interleaved phases and a half-symmetry, state-space representation of the circuit. The model is experimentally verified using a 32-kW, 350-V prototype that owns 7.6 kW/kg and 97.1% of power density and efficiency, respectively. A description of the controller, developed in a high-performance microcontroller, is also presented together with the experimental verification, detailing the design of the compensating ramp for a wide load range. Measured results are contrasted with the sample-data model predictions, using both transient and frequency responses, and evaluating the controlled converter dynamics at 14, 21, 26, and 30 kW. The comparison reveals the effective validity of the presented sample-data model and the effects of the supply to the dynamic performance of the high-density converter. [ABSTRACT FROM AUTHOR]

Solar panels, which have become a good choice, are used to generate and supply electricity in commercial and residential applications. This generated power starts with the solar cells, which have a complex relationship between solar irradiation, temperature, and output power. For this reason a tracking of the maximum power point is required. Traditionally, this has been made by considering just current and voltage conditions at the photovoltaic panel; however, temperature also influences the process. In this paper the voltage, current, and temperature in the PV system are considered to be a part of a sliding surface for the proposed maximum power point tracking; this means a sliding mode controller is applied. Obtained results gave a good dynamic response, as a difference from traditional schemes, which are only based on computational algorithms. A traditional algorithm based on MPPT was added in order to assure a low steady state error. [ABSTRACT FROM AUTHOR]

This article proposes a virtual sensor for piecewise linear systems based on observability analysis that is in function of a commutation law related with the system's outpu. This virtual sensor is also known as a state estimator. Besides, it presents a detector of active mode when the commutation sequences of each linear subsystem are arbitrary and unknown. For the previous, this article proposes a set of virtual estimators that discern the commutation paths of the system and allow estimating their output. In this work a methodology in order to test the observability for piecewise linear systems with discrete time is proposed. An academic example is presented to show the obtained results. [ABSTRACT FROM AUTHOR]

Local path planning is a key task for the motion planners of autonomous vehicles since it commands the vehicle across its environment while avoiding any obstacles. To perform this task, the local path planner generates a trajectory and a velocity profile, which are then sent to the vehicle's actuators. This paper proposes a new local path planner for autonomous vehicles based on the Attractor Dynamic Approach (ADA), which was inspired by the behavior of movement of living beings, along with an algorithm that takes into account four acceleration policies, the ST dynamic vehicle model, and several constraints regarding the comfort and security. The original functions that define the ADA were modified in order to adapt it to the non-holonomic vehicle's constraints and to improve its response when an impact scenario is detected. The present approach is validated in a well-known simulator for autonomous vehicles under three representative cases of study where the vehicle was capable of generating local paths that ensure the security of the vehicle in such cases. The results show that the approach proposed in this paper is a promising tool for the local path planning of autonomous vehicles since it is able to generate trajectories that are both safe and efficient. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to explore the application of detrended fluctuation analysis (DFA) to study roughness features of images. Unidimensional sequences at different image orientations are extracted and their average scaling exponent is estimated. In this form, the existence of anisotropies can be detected when considerable variations in the scaling exponent at different image orientation are observed. Different images from grass to solar granulation are analyzed and the underlying physics of such results is briefly commented. [Copyright &y& Elsevier]

The design and tuning of power system stabilizers (PSS) and automatic voltage regulators (AVR) of synchronous generators is usually performed using low-order two-axis models. Remarkable robust characteristics and systematic construction can be obtained with the recent developments on linear and nonlinear control theory. However, the properties and performance of the control designs are also evaluated using low-order equivalent-circuit models because large synchronous machines are not readily available to designers and researches. This may lead to doubts about the controller behavior under true operating conditions. The main objective of this work is to show that robust control designs, obtained with small order models, keep their good performance characteristics when applied to the actual machine. In order to circumvent the lack of the real machine, a very detailed finite-element model is developed to represent turbine generators connected to large power systems. The numerical model incorporates simulation of rotor motion, iron magnetic nonlinearity and eddy currents in the solid rotors of turbine generators. The control design is performed using constructive nonlinear control, which gives a systematic controller construction coupled to a simple tuning scheme. [Copyright &y& Elsevier]

This paper addresses the position regulation problem of robot manipulators under control input constraints. It is proven that the robot system under a saturated linear PID control is semiglobally asymptotically stable, if the torque bounds are larger than gravitational torques, and if the proportional gain is large enough and the integral gain is small enough.The stability analysis makes use of singular perturbation tools and the results are illustrated via numerical simulations. [Copyright &y& Elsevier]

Addresses the problem of designing a robust tracking controller for a nonlinear Chua's circuit involving plant uncertainties and external disturbances. Use of Chua's circuits in the study of the dynamics and control of nonlinear circuits; Basis of the development of a robust tracking controller; Characteristic of the developed controller.

A two-phase buck–boost converter utilizing dual interleaving is presented in this article. The dual interleaving consists of an interphase transformer (IPT) that doubles the ripple frequency together with two conventional buck–boost switching arms, mitigating the inductor ripple current and aiding to increase the power density of the converter. A description of the design and selection of the power devices is presented for a 32-kW, 75-kHz dual interleaved SiC prototype with an IPT, such that a power density of 7.4 kW/kg is achieved. The operation of the circuit is verified experimentally using a prototype with 315–385 V supply range and 350-V output voltage, achieving 97.1% peak efficiency at 32 kW. The experiments reveal that the interleaved coupled currents are equalized without an active balancer. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes a switching control strategy (SCS) for a bidirectional DC/DC converter. The aim of this strategy is managing the power that an ultra-capacitor (UC) has to deliver or absorb following a power reference required by the driving cycle ECE-15 of an electric vehicle (EV). For that purpose, the converter is modelled as a switched linear system. Based on hysteresis and logic switching, a switching rule is designed. Necessary and sufficient conditions for the existence of the switching rule are established. Simulation and experimental results of a 1 kW converter are shown to demonstrate the feasibility of this strategy. Highlights • A switching rule for a bidirectional DC/DC power converter for an EV is designed. • Switching rule is based on existence conditions of practical stabilizability. • Switching rule avoids the discontinuous conduction mode of the power converter. • Scale-down power consumption using a driving cycle ECE-15 was used for tests. • Inductor current tracking is achieved in one switching period. [ABSTRACT FROM AUTHOR]

This paper analyzes the stability and switching controllability properties of a single-phase PWM rectifier and its relationship with parameter uncertainty. Based on this analysis, a switching control strategy is proposed that has as objectives (i) to achieve input current tracking and low current THD (total harmonic distortion) as well as (ii) to regulate the output voltage in spite of perturbations. The proposed control does not require a PWM generation step design. Numerical simulations and experimental tests in a 1 kW prototype demonstrate the effectiveness of the proposed controller and illustrate the limits of system's controllability. [ABSTRACT FROM AUTHOR]

Traditionally DC-AC converters are considered with voltage source inverters (VSI); although less studied and discussed, it has started recently to be used current source inverters (CSI). Another possibility forDC/AC conversion is themultilevel configuration. This paper shows experimental operation and simulation analysis of a grid-connected multilevel current source inverter (MCSI), which includes a circuit for equipment safety reasons due to grid disconnections. [ABSTRACT FROM AUTHOR]