Performance Analysis Of Non-Linear Adaptive Control Laws Using Hardware in the Loop of an Unmanned Aerial System

In practical applications, an Unmanned Aerial System\u27s (UAS) baseline performance is dictated by how well it can follow a given trajectory with limited stress on the actuators. However, these can be insufficient performance metrics when the UAS is allowed to adapt to an unpredicted external influence such as turbulence or actuation failure, while maintaining a satisfactory baseline performance. In this thesis, different control laws based on the formation flight geometry problem, nonlinear dynamic inversion and an artificial immune system adaptive mechanism , are implemented in hardware-in-the-loop as a precursor for in-flight testing. These controllers are compared based on three performance metrics: trajectory following, control activity and computer task execution time. The controllers chosen for comparison are: Basic Proportional-Integral-Derivative (PID), Outer loop Non-Linear Dynamic Inversion (NLDI), Extended NLDI, and the previous three controllers augmented with an AIS for a total of six controllers. The Extended NLDI augmented with the AIS outperformed all of the other algorithms under falure conditions on a global scale

Examining healthcare needs and decisions to seek health services among Venezuelan migrants living in Trinidad and Tobago using Andersen’s Behavioral Model

IntroductionBeginning in 2016, Trinidad and Tobago experienced increasing flows of migrants and refugees from Venezuela. Through a Government Registration Exercise in 2019, followed by a Re-registration Exercise in 2020, migrants and refugees benefitted from access to publicly available primary care and emergency medical services. By applying Andersen’s Behavioral Model for Health Service Use, our study examined the non-communicable disease care needs of migrants, and factors influencing their decision to seek public and private health services.MethodBetween September and December 2020, a health questionnaire was administered via telephone to n = 250 migrants from Venezuela. Descriptive statistics summarized the constructs of Andersen’s Behavioral Model. The model comprised of predisposing factors including migrants’ social characteristics; enabling factors namely monthly earnings, education level and most trusted source of information on medical needs; need for care factors such as migrants self-reported health status, presence of non-communicable health conditions and having visited a doctor in the past 12 months; and the outcome variables which were migrants’ decisions to seek public and private health services. Pearson χ2 tests, odds ratios and multivariable logistic regression with backward elimination examined the factors influencing a migrant’s decision to seek health services.ResultsOverall, 66.8% of migrants reported they would seek public health services, while 22.4% indicated they would seek private health services. Predisposing factors namely length of time residing in Trinidad and Tobago (p = 0.031) and living with family/friends (p = 0.049); the enabling factor of receiving information from publicly available sources (p = 0.037); and the need for care factor of visiting a doctor for a physical health problem (p = 0.010) were significant correlates of their decision to seek care in the public sector. Predisposing factors namely living with family/friends (p = 0.020) and the enabling factor of having difficulty accessing healthcare services (p = 0.045) were significant correlates of their decision to seek care from private providers.DiscussionOur findings demonstrated the positive association between social networks and a migrant’s decision to use public and private health services, thus underscoring the importance of family and friends in facilitating health service use, promoting proper health practices and preventing diseases. Overall, the use of Andersen’s Behavioral Model aided in identifying the factors associated with the use of health services by Venezuelan migrants in Trinidad and Tobago. However, further studies are needed to better understand their need for ongoing care, to inform policy, and to plan targeted health interventions for addressing the gaps in health service access, barriers and use

Factors Affecting COVID-19 Vaccination Intentions among Patients Attending a Large HIV Treatment Clinic in Trinidad Using Constructs of the Health Belief Model

Persons living with HIV are particularly vulnerable to COVID-19 and understanding the factors influencing their decision to take the COVID-19 vaccine are crucial. Using the Health Belief Model (HBM), our study examined the role of psychological factors in predicting vaccine intention in patients with HIV. The underlying concept of the HBM is that behaviour is determined by personal beliefs about a disease, and access to strategies to decrease its occurrence. A cross-sectional survey using a structured questionnaire was conducted between August and September 2021 at an HIV clinic in Trinidad. Data on the HBM constructs, namely patient’s beliefs about the perceived severity and susceptibility to COVID-19, their perceived benefits of taking the vaccine, and external cues to action, i.e., factors that may motivate them to take the vaccine, were collected. Univariate and multivariable logistic regression analyses were used to examine associations and whether the HBM components were predictors of vaccination intention. In this study, 59.9% of patients indicated their intentions to take the vaccine. Females (OR 0.49, 95% CI 0.30–0.81) were less inclined to take the COVID-19 vaccine compared to males, while Indo-Trinidadian patients with HIV (OR 4.40, 95% CI 1.26–15.3) were more inclined to take the vaccine compared to Afro-Trinidadians. Health beliefs such as having confidence in the vaccine (p = 0.001) and believing in its perceived benefits (p = 0.001) were significant predictors of vaccination intention. Patients who were confident about the vaccine were six times more likely to take the vaccine (OR 6.45, 95% CI 2.13–19.5) than persons who were not confident in it. Having adequate information about the vaccine or the knowledge of others who received the vaccine (OR 1.48, 95% CI 1.03–2.11) were significant cues to action influencing their decision. Guided by the HBM, understanding patient’s health beliefs is important in the design of tailored interventions to improve vaccine outcomes. The HBM may also be useful in the design of approaches to increase the uptake of critical HIV prevention, and treatment services

Performance Analysis of Fault Tolerant UAV Baseline Control Laws with L1 Adaptive Augmentation

In this paper, the performance of L1 adaptive control laws is investigated in the presence of aircraft actuator failures and atmospheric turbulence. L1 adaptive control is combined with a linear type controller and a nonlinear dynamic inversion-based outer/inner loop controller. Specific evaluation metrics are defined in terms of trajectory tracking errors and control activity during autonomous flight. Several types of trajectories with different levels of complexity are considered in this research effort. The West Virginia University unmanned aerial vehicle simulation environment is used in this analysis. The results show that the adaptive augmentation improves the tracking performance of the vehicle at nominal conditions and under a variety of abnormal flight conditions

Elevated mercury exposure in communities living alongside the Inanda Dam, South Africa

Mercury is a persistent heavy metal that has been associated with damage to the central nervous system, including hearing and speech impairment, visual constriction and loss of muscle control. In aquatic environments mercury may be methylated to its most toxic form, methyl-mercury. In 1990 concerns were raised over mercury contamination in the vicinity of a mercury processing plant in KwaZulu-Natal, South Africa. Mercury waste was reported to have been discharged into the Mngceweni River, situated in close proximity to the plant. The Mngceweni River joins the uMgeni River, which in turn flows into the Inanda Dam, along the banks of which several villages are located. This study evaluated the mercury levels in river and dam sediments, fish from the Inanda Dam and hair samples collected from residents of three villages along the banks of the Inanda Dam. The study results showed that 50% of the fish samples and 17% of hair samples collected from villagers had mercury concentrations that exceeded guideline levels of the World Health Organization. Mercury concentrations in 62% of the river sediment samples collected in close proximity to the former mercury processing plant exceeded the level at which remedial action is required according to legislation in the Netherlands. These preliminary findings give reasons for concern and should be used as a baseline for further investigations