Hybrid Planning and Control for Multiple Fixed-Wing Aircraft under Input Constraints

This paper presents a novel hybrid control protocol for de-conflicting multiple vehicles with constraints on control inputs. We consider turning rate and linear speed constraints to represent fixed-wing or car-like vehicles. A set of state-feedback controllers along with a state-dependent switching logic are synthesized in a hybrid system to generate collision-free trajectories that converge to the desired destinations of the vehicles. The switching law is designed so that the safety can be guaranteed while no Zeno behavior can occur. A novel temporary goal assignment technique is also designed to guarantee convergence. We analyze the individual modes for safety and the closed-loop hybrid system for convergence. The theoretical developments are demonstrated via simulation results.Comment: Best Student Paper Finalist, AIAA-SciTech GNC Conference, 201

Neurocognitive Consequences of HIV Infection in Older Adults: An Evaluation of the “Cortical” Hypothesis

The incidence and prevalence of older adults living with HIV infection is increasing. Recent reports of increased neuropathologic and metabolic alterations in older HIV+ samples, including increased cortical beta-amyloid, have led some researchers to suggest that aging with HIV may produce a neuropsychological profile akin to that which is observed in “cortical” dementias (e.g., impairment in memory consolidation). To evaluate this possibility, we examined four groups classified by HIV serostatus and age (i.e., younger ≤40 years and older ≥50 years): (1) Younger HIV− (n = 24); (2) Younger HIV+ (n = 24); (3) Older HIV− (n = 20); and (4) Older HIV+ (n = 48). Main effects of aging were observed on episodic learning and memory, executive functions, and visuoconstruction, and main effects of HIV were observed on measures of verbal learning and memory. The interaction of age and HIV was observed on a measure of verbal recognition memory, which post hoc analyses showed to be exclusively attributed to the superior performance of the younger HIV seronegative group. Thus, in this sample of older HIV-infected individuals, the combined effects of HIV and aging do not appear to result in a “cortical” pattern of cognitive deficits

Analysis and design of event-Triggered control algorithms using hybrid systems tools

This paper proposes a general framework for analyzing continuous-Time systems controlled by event-Triggered algorithms. Closed-loop systems resulting from using both static and dynamic output (or state) feedback laws that are implemented via asynchronous event-Triggered techniques are modeled as hybrid systems given in terms of hybrid inclusions and studied using recently developed tools for robust stability. Properties of the proposed models, including stability of compact sets, robustness, and Zeno behavior of solutions are addressed. The framework and results are illustrated in several event-Triggered strategies available in the literature

Analysis and design of event-Triggered control algorithms using hybrid systems tools

This paper proposes a general framework for analyzing continuous-Time systems controlled by event-Triggered algorithms. Closed-loop systems resulting from using both static and dynamic output (or state) feedback laws that are implemented via asynchronous event-Triggered techniques are modeled as hybrid systems given in terms of hybrid inclusions and studied using recently developed tools for robust stability. Properties of the proposed models, including stability of compact sets, robustness, and Zeno behavior of solutions are addressed. The framework and results are illustrated in several event-Triggered strategies available in the literature

Portuguese Wood Pellets Market: Organization, Production and Consumption Analysis

Wood pellets are a form of energy that can be seen as an alternative to fossil fuels, thus contributing to the reduction of greenhouse gas emissions. In other words, wood pellets can be considered a solution contributing to the mitigation of climate change. The use of wood pellets has grown significantly in recent years, with different markets emerging, such as Portugal, both from production and consumption perspectives. The wood pellet industry in Portugal began its development about 15 years ago, with the companies installed in the country initially almost exclusively dedicated to the production of wood pellets for export to central and northern European markets. However, over the years, the domestic market, initially considered insignificant, began to develop; it recently reached a considerable consuming share of the national production. This study presents an analysis of the Portuguese wood pellet market using data collected on the sector, and specifically on producers and consumers. The information was gathered using surveys presented directly to consumers and producers and through interviews with other stakeholders in the sector. From the analysis of the information, it was possible to understand the market’s dynamics, its current evolution and its prospects for the upcoming years, since it can already be considered mature and consolidated

Residual Biomass: A Comprehensive Review on the Importance, Uses and Potential in a Circular Bioeconomy Approach

The paradigm shift towards sustainable growth is urgent, and biomass, which is the oldest energy source that humans have used since the discovery of fire, might play an important role. Biomass waste from forestry and agriculture is expected to fuel part of the increasing demand for biomass, and its valorization allows for more the efficient use of nutrients and resources. In this study, we carried out an extensive literature review on the valorization of residual agroforestry biomass since the 1970s to understand the leading research focuses on the subject over the last few decades, identify the most recent trends, and establish a possible solution path for the future of biomass. It was observed that most studies focused on biomass as being capable of replacing fossil energy sources. According to the literature, biomass has the most significant potential to meet requirements and ensure fuel supplies in the future. The developments of the last decades have significantly improved the conversion processes, leading to greener solutions, but there is still much to be studied and put into practice. Closing the loop into biomass waste recovery will be essential for a genuinely circular bioeconomy

Portuguese Wood Pellets Market: Organization, Production and Consumption Analysis

Wood pellets are a form of energy that can be seen as an alternative to fossil fuels, thus contributing to the reduction of greenhouse gas emissions. In other words, wood pellets can be considered a solution contributing to the mitigation of climate change. The use of wood pellets has grown significantly in recent years, with different markets emerging, such as Portugal, both from production and consumption perspectives. The wood pellet industry in Portugal began its development about 15 years ago, with the companies installed in the country initially almost exclusively dedicated to the production of wood pellets for export to central and northern European markets. However, over the years, the domestic market, initially considered insignificant, began to develop; it recently reached a considerable consuming share of the national production. This study presents an analysis of the Portuguese wood pellet market using data collected on the sector, and specifically on producers and consumers. The information was gathered using surveys presented directly to consumers and producers and through interviews with other stakeholders in the sector. From the analysis of the information, it was possible to understand the market’s dynamics, its current evolution and its prospects for the upcoming years, since it can already be considered mature and consolidated

Coal to Biomass Transition as the Path to Sustainable Energy Production: A Hypothetical Case Scenario with the Conversion of Pego Power Plant (Portugal)

Fossil fuels, especially coal, contribute to carbon emissions, hindering the EU’s decarbonization goal by 2050. This article proposes converting the Pego Coal Power Plant into a biomass plant as a potential solution. Biomass, a renewable resource abundant in Portugal, can transform the Pego plant into a sustainable energy source, reducing greenhouse gas emissions and combating climate change. It also reduces rural fire risks and ensures regional social and economic stability. The study explores the feasibility, limitations, and socioeconomic impacts of this scenario. This solution prevents plant closure, reduces environmental impacts, and promotes sustainability. Aligning with Portugal’s 2030 Agenda and global climate change efforts, converting the Pego plant serves as a valuable example of renewable resource utilization for climate change mitigation and regional stability. The study’s results offer insights for policymakers and stakeholders in developing sustainable energy transition strategies. Adopting such solutions can help countries achieve decarbonization goals while promoting social and economic development