Linear motor motion control using a learning feedforward controller

The design and realization of an online learning motion controller for a linear motor is presented, and its usefulness is evaluated. The controller consists of two components: (1) a model-based feedback component, and (2) a learning feedforward component. The feedback component is designed on the basis of a simple second-order linear model, which is known to have structural errors. In the design, an emphasis is placed on robustness. The learning feedforward component is a neural-network-based controller, comprised of a one-hidden-layer structure with second-order B-spline basis functions. Simulations and experimental evaluations show that, with little effort, a high-performance motion system can be obtained with this approach

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Stability analysis of learning feed-forward control

In this paper, a learning control system is considered for motion systems that are subject to two types of disturbances; reproducible disturbances, that re-occur each run in the same way, and random disturbances. In motion systems, a large part of the disturbances appear to be reproducible. In the control system considered, the reproducible disturbances are compensated by a learning component consisting of a B-spline neural network that is operated in feed-forward. The paper presents an analysis of stability properties of the con&amp;quot;guration in case of a linear process and second-order B-splines. The outcomes of the analysis are quantitative criteria for selection of the width of the B-splines, and of the learning rate, for which the system is guaranteed to be stable. These criteria facilitate the design of a learning feed-forward controller

Imprinted conjugated polymer laser

A new simple soft-lithographic method was developed and applied to realize optical structures on the mesoscopic scale directly in a conjugated polymer. The imprinted DFB grating gave rise to laser action upon photoexcitation

A Delphi study to construct a CanMEDS competence based inventory applicable for workplace assessment

BACKGROUND: During workplace based learning students develop professional competences and an appropriate performance. To gain insight in the learning process and to evaluate competences and performance, assessment tools are essential and need to be of good quality. We aimed to construct a competence inventory applicable as an instrument to measure the content validity of workplace based assessment tools, such as portfolio. METHODS: A Delphi study was carried out based on the CanMEDS Roles Framework. In three rounds, experts (N = 25–30) were invited to score the key competences per CanMEDS role on relevance (6-point Likert-scale), and to comment on the content and formulation bearing in mind its use in workplace based assessment. A descriptive analysis of relevances and comments was performed. RESULTS: Although all competences were scored as relevant, many comments pointed at a lack of concrete, transparent and applicable descriptions of the key competences for the purpose of assessment. Therefore, the CanMEDS roles were reformulated in this Delphi procedure as concrete learning outcomes, observable and suitable for workplace based assessment. CONCLUSIONS: A competence based inventory, ready for validating workplace based assessment tools, was constructed using a Delphi procedure and based on a clarification and concretisation of the CanMEDS roles