Index Information Algorithm with Local Tuning for Solving Multidimensional Global Optimization Problems with Multiextremal Constraints

Multidimensional optimization problems where the objective function and the constraints are multiextremal non-differentiable Lipschitz functions (with unknown Lipschitz constants) and the feasible region is a finite collection of robust nonconvex subregions are considered. Both the objective function and the constraints may be partially defined. To solve such problems an algorithm is proposed, that uses Peano space-filling curves and the index scheme to reduce the original problem to a H\"{o}lder one-dimensional one. Local tuning on the behaviour of the objective function and constraints is used during the work of the global optimization procedure in order to accelerate the search. The method neither uses penalty coefficients nor additional variables. Convergence conditions are established. Numerical experiments confirm the good performance of the technique.Comment: 29 pages, 5 figure

Nutrient Uptake Among Urban and Non-Urban Streams Within the Piedmont Physiographic Province of Virginia

To assess how urbanization impacts stream nutrient uptake, a series of instantaneous (i.e. slug) nutrient additions were conducted in 3 urban and 3 non-urban streams during open and closed canopy conditions. Single additions of N, P, and combined additions of N and P were performed at each site. These data were used to test the hypothesis that high N:P concentrations in urban streams would result in P-limited conditions, and to assess differences in nutrient uptake kinetics (i.e., the relationship between uptake and concentration) between urban and non-urban streams. The results show that there were no consistent differences in N vs. P limitation among urban and non-urban streams suggesting that ambient N:P ratios are not useful predictors of nutrient limitation at the ecosystem scale. Areal uptake rates of N in urban streams were greater than non-urban streams coinciding with elevated N concentrations. Conversely, areal uptake rates of P were similar between urban and non-urban streams because these systems have similar ambient concentrations of P. Urban and non-urban streams demonstrated similar uptake velocity and areal uptake rate responses to increasing nutrient concentrations. However, unique to this study, urban streams had greater uptake velocities at ambient nutrient concentrations. These findings suggest that urban streams could have a greater capacity for nutrient uptake over a broad range of nutrient concentrations, but prior work indicates that this capacity may be constrained by the duration of the nutrient addition

Observer-Based Nonlinear Dynamic Inversion Adaptive Control with State Constraints

Hypersonic vehicle research and development has grown recently in the aerospace industry due to the powerful potential of operating a vehicle that flies at substantially higher speeds than typical aircraft. From a guidance, navigation and control perspective, hypersonic vehicles are particularly interesting due both to inherent vehicle complexities as well as practical concerns that only arise at high Mach numbers. Challenges inherent to the vehicle include nonlinearities, a wide range of operating conditions, high elasticity, high temperatures and parametric uncertainty. Although these challenges have by no means fully been explored in the literature, in the realm of control theory, they are somewhat common. Hypersonic vehicle control is difficult however, because in addition to these more traditional complexities a control designer must also deal with problems very specific to flying at high speeds such as: inlet unstart, overcoming sensing deficiencies at high speeds and creating an implementable digital control framework for a plant with extremely fast dynamics. This dissertation develops three novel theoretical approaches for addressing these challenges through advances in the nonlinear dynamic inversion adaptive control technique. Although hypersonic vehicle control is the motivation and often the application that the control algorithms in this dissertation are tested on, several of the theoretical developments apply to a general class of nonlinear continuous time systems. First, in order to address the problem of inlet unstart, two state constraint mechanisms which integrate into the nonlinear dynamic inversion adaptive control framework are presented. These state constraining control laws require full state feedback and are capable of restricting the outputs of nonlinear systems containing parameter uncertainty to specific regions of the state-space. The first state constraint mechanism achieves this objective using sliding mode control and the second uses bounding functions to smoothly adjust the control and adaptive laws and drive the states toward the origin when constraints are approached. Stability is proven using Lyapunov analysis and these techniques are demonstrated in a nonlinear simulation of a hypersonic vehicle. Second, an observer-based feedback controller is developed that allows for a nonlinear system to track a reference trajectory with bounded errors and without measuring multiple states. Again, the technique used is nonlinear dynamic inversion adaptive control, but because of uncertainty in the system state, it is not assumed that the nonlinear control effectiveness matrix can be canceled perfectly. A nonlinear observer is implemented to estimate the values of the unknown states. This observer allows for the closed-loop stability of the system to be proven through Lyapunov analysis. It is shown that parametric uncertainty can successfully be accounted for using an adaptive mechanism and that all tracking and estimation errors are uniformly ultimately bounded. Finally, a sampled-data nonlinear dynamic inversion adaptive control architecture is introduced. Despite the prevalence of digital controllers in practice, a nonlinear dynamic inversion adaptive control scheme in a sampled-data setting has not previously been developed. The method presented in this dissertation has the capability of extending the benefits of nonlinear dynamic inversion adaptive control - robust control of nonlinear systems with respect to model uncertainty - to more practical platforms

A receding horizon event-driven control strategy for intelligent traffic management

AbstractIn this paper, the intelligent traffic management within a smart city environment is addressed by developing an ad-hoc model predictive control strategy based on an event-driven formulation. To this end, a constrained hybrid system description is considered for safety verification purposes and a low-demanding receding horizon controller is then derived by exploiting set-theoretic arguments. Simulations are performed on the train-gate benchmark system to show the effectiveness and benefits of the proposed methodology

Robust finite-time stability design via linear matrix inequalities

For linear systems with polytopic uncertainties, the problem of robust finite-time stabilization is reduced to a system of Linear Matric Inequalities

Analytic Gain and Phase Margin Design

In 5, algorithms are presented for analytic gain and phase margin design. Without special care however, the compensator computed with this algorithm is not a real rational function. In 3, it is shown that with some care, a real rational compensator for phase margin design can be computed from the theory in 5. In this paper both gain and phase margin problems are reduced to interpolation problems with positive-real functions, which saves a step in the algorithm shown in 5, where interpolation is done with bounded-real functions, in the case of gain margin design

Proposed Healthcare Initiatives to Mitigate Opioid Risk and Advance Safety of Pain Management

Between 1999 and 2017 more than 400,000 people died due to an opioid-related death from both prescription and illicit use.1 Opioid overdose can occur as a result of accidental misuse of a legitimate prescription or as a result of intentional drug abuse, and it is among the most preventable public health threats facing the United States. Numerous initiatives and strategies have been proposed and implemented to help with the growing opioid issue. This report aims to provide insight into programs and products available in the United States which address mitigation strategies to promote safe and appropriate opioid prescribing

EL LEGADO DE LAS CONFERENCIAS LATINOAMERICANAS DE SORDOS

El propósito de este trabajo es dar cuenta del legado de las dos conferencias latinoamericanas de Sordos organizadas por la Confederación Argentina de Sordomudos, en adelante CAS, a cargo de la Secretaría Regional de la Federación Mundial de Sordos (FMS), en Buenos Aires, en abril de 1970 y noviembre de 1985. La investigación aplicada, de carácter descriptivo y explicativo, se basó en un análisis de publicaciones de época, testimonios, artículos y textos inéditos. Los resultados evidenciaron la repercusión de las dos conferencias a través de las discusiones e intervenciones de diferentes actores, Sordos y Oyentes. Las conclusiones de estas señalan, hace casi medio siglo, un punto de partida que evidencia una modificación de las actitudes hacia la cultura Sorda, la lengua de señas y la interpretación en lengua de señas -lengua oral en Latinoamérica. Este cambio de perspectiva se afianzó con el correr de las décadas posteriores. Al no existir actas escritas de estas conferencias, nos resulta pertinente recuperar, para la memoria colectiva, las circunstancias sociohistóricas de estos dos momentos de la cultura e historia Sordas reflejadas a través de diferentes fuentes