180 research outputs found

    Reduced order modeling of non-linear monopile dynamics via an AE-LSTM scheme

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    Non-linear analysis is of increasing importance in wind energy engineering as a result of their exposure in extreme conditions and the ever-increasing size and slenderness of wind turbines. Whilst modern computing capabilities facilitate execution of complex analyses, certain applications which require multiple or real-time analyses remain a challenge, motivating adoption of accelerated computing schemes, such as reduced order modelling (ROM) methods. Soil structure interaction (SSI) simulations fall in this class of problems, with the non-linear restoring force significantly affecting the dynamic behaviour of the turbine. In this work, we propose a ROM approach to the SSI problem using a recently developed ROM methodology. We exploit a data-driven non-linear ROM methodology coupling an autoencoder with long short-term memory (LSTM) neural networks. The ROM is trained to emulate a steel monopile foundation constrained by non-linear soil and subject to forces and moments at the top of the foundation, which represent the equivalent loading of an operating turbine under wind and wave forcing. The ROM well approximates the time domain and frequency domain response of the Full Order Model (FOM) over a range of different wind and wave loading regimes, whilst reducing the computational toll by a factor of 300. We further propose an error metric for capturing isolated failure instances of the ROM

    Distributed digital real-time control system for the TCV tokamak and its applications

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    A key feature of the new digital plasma control system installed on the TCV (Tokamak à Configuration Variable) tokamak is its possibility to rapidly design, test and deploy real-time algorithms. It accommodates hundreds of diagnostic inputs and actuator outputs, and offers the possibility to design advanced control algorithms with better knowledge of the plasma state and to coherently control all TCV actuators, including poloidal field coils, gas valves, the gyrotron powers and launcher angles of the electron cyclotron heating and current drive system together with diagnostic triggering signals. It encompasses plasma control applications ranging from basic experiments of coil current and density control to advanced experiments of magnetohydrodynamics (MHD) and plasma profile control. The system consists of multiple nodes, each of which may have a local analog to digital (ADC) and/or digital to analog (DAC) card; all nodes are connected to a reflective memory (RFM), providing a deterministic method of sharing memory between them. Recently, a generalized plasma position and shape controller based on the real-time (RT) Grad-Shafranov solver RTLIUQE was developed and implemented, providing the basis for future high performance plasma operation with advanced plasma configurations. The controller design is based on an isoflux control scheme and utilizes singular value decomposition (SVD), to respect the limits on poloidal field coils currents by limiting the controlled parameters to the set that can be more easily controlled. The controller is capable in principle of providing improved equilibrium control especially for unconventional plasma scenarios, for e.g. reliable control of 'snowflake' equilibria with closely spaced x-points, i.e. the 'exact' snowflake, and the development of negative triangularity plasmas in H-mode. An addition of a new node on the digital control system has enhanced the real time computational capacity and hosts the real-time transport code RAPTOR (rapid plasma transport simulator), an advanced density profile reconstruction algorithm including real-time fringe jump correction, as well as a plasma state monitoring, supervision and actuator management algorithm. In future, more signals from existing TCV diagnostics, including multiview pinhole x-ray diagnostics, Thomson scattering, visible image processing and magnetic signals for MHD mode analysis will be added to expand the capabilities of the digital control system

    Comorbidity, not patient age, is associated with impaired safety outcomes in vedolizumab- and ustekinumab-treated patients with inflammatory bowel disease-a prospective multicentre cohort study

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    Background: Few data are available on the effects of age and comorbidity on treatment outcomes of vedolizumab and ustekinumab in inflammatory bowel disease (IBD). Aims: To evaluate the association between age and comorbidity with safety and effectiveness outcomes of vedolizumab and ustekinumab in IBD. Methods: IBD patients initiating vedolizumab or ustekinumab in regular care were enrolled prospectively. Comorbidity prevalence was assessed using the Charlson Comorbidity Index (CCI). Association between age and CCI, both continuously assessed, with safety outcomes (any infection, hospitalisation, adverse events) during treatment, and effectiveness outcomes (clinical response and remission, corticosteroid-free remission, clinical remission combined with biochemical remission) after 52 weeks of treatment were evaluated. Multivariable logistic regression was used to adjust for confounders. Results: We included 203 vedolizumab- and 207 ustekinumab-treated IBD patients, mean age 42.2 (SD 16.0) and 41.6 (SD 14.4). Median treatment duration 54.0 (IQR 19.9-104.0) and 48.4 (IQR 24.4-55.1) weeks, median follow-up time 104.0 (IQR 103.1-104.0) and 52.0 weeks (IQR 49.3-100.4). On vedolizumab, CCI associated independently with any infection (OR 1.387, 95% CI 1.022-1.883, P = 0.036) and hospitalisation (OR 1.586, 95% CI 1.127-2.231, P = 0.008). On ustekinumab, CCI associated independently with hospitalisation (OR 1.621, 95% CI 1.034-2.541, P = 0.035). CCI was not associated with effectiveness, and age was not associated with any outcomes. Conclusions: Comorbidity - but not age - is associated with an increased risk of hospitalisations on either treatment, and with any infection on vedolizumab. This underlines the importance of comorbidity assessment and safety monitoring of IBD patients

    Describing the profile of diagnostic features in autistic adults using an abbreviated version of the Diagnostic Interview for Social and Communication Disorders (DISCO-Abbreviated)

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    The rate of diagnosis of autism in adults has increased over recent years; however, the profile of behaviours in these individuals is less understood than the profile seen in those diagnosed in childhood. Better understanding of this profile will be essential to identify and remove potential barriers to diagnosis. Using an abbreviated form of the Diagnostic Interview for Social and Communication Disorders, comparisons were drawn between the profile of a sample of able adults diagnosed in adulthood and the profile of a sample of able children. Results revealed both similarities and differences. A relative strength in non-verbal communication highlighted a potential barrier to diagnosis according to DSM-5 criteria for the adult sample, which may also have prevented them from being diagnosed as children

    Fat emulsion intragastric stability and droplet size modulate gastrointestinal responses and subsequent food intake in young adults

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    Background: Intragastric creaming and droplet size of fat emulsions may affect intragastric behavior and gastrointestinal and satiety responses.Objectives: We tested the hypotheses that gastrointestinal physiologic responses and satiety will be increased by an increase in intragastric stability and by a decrease in fat droplet size of a fat emulsion.Methods: This was a double-blind, randomized crossover study in 11 healthy persons [8 men and 3 women, aged 24 ± 1 y; body mass index (in kg/m2): 24.4 ± 0.9] who consumed meals containing 300-g 20% oil and water emulsion (2220 kJ) with 1) larger, 6-μm mean droplet size (Coarse treatment) expected to cream in the stomach; 2) larger, 6-μm mean droplet size with 0.5% locust bean gum (LBG; Coarse+LBG treatment) to prevent creaming; or 3) smaller, 0.4-μm mean droplet size with LBG (Fine+LBG treatment). The participants were imaged hourly by using MRI and food intake was assessed by using a meal that participants consumed ad libitum.Results: The Coarse+LBG treatment (preventing creaming in the stomach) slowed gastric emptying, resulting in 12% higher gastric volume over time (P < 0.001), increased small bowel water content (SBWC) by 11% (P < 0.01), slowed appearance of the 13C label in the breath by 17% (P < 0.01), and reduced food intake by 9% (P < 0.05) compared with the Coarse treatment. The Fine+LBG treatment (smaller droplet size) slowed gastric emptying, resulting in 18% higher gastric volume (P < 0.001), increased SBWC content by 15% (P < 0.01), and significantly reduced food intake by 11% (P < 0.05, equivalent to an average of 411 kJ less energy consumed) compared with the Coarse+LBG treatment. These high-fat meals stimulated substantial increases in SBWC, which increased to a peak at 4 h at 568 mL (range: 150–854 mL;P < 0.01) for the Fine+LBG treatment.Conclusion: Manipulating intragastric stability and fat emulsion droplet size can influence human gastrointestinal physiology and food intake

    Is There a Place for Dietary Fiber Supplements in Weight Management?

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    Inadequate dietary fiber intake is common in modern diets, especially in children. Epidemiological and experimental evidence point to a significant association between a lack of fiber intake and ischemic heart disease, stroke atherosclerosis, type 2 diabetes, overweight and obesity, insulin resistance, hypertension, dyslipidemia, as well as gastrointestinal disorders such as diverticulosis, irritable bowel disease, colon cancer, and cholelithiasis. The physiological effects of fiber relate to the physical properties of volume, viscosity, and water-holding capacity that the fiber imparts to food leading to important influences over the energy density of food. Beyond these physical properties, fiber directly impacts a complex array of microbiological, biochemical, and neurohormonal effects directly through modification of the kinetics of digestion and through its metabolism into constituents such as short chain fatty acids, which are both energy substrates and important enteroendocrine ligands. Of particular interest to clinicians is the important role dietary fiber plays in glucoregulation, appetite, and satiety. Supplementation of the diet with highly functional fibers may prove to play an important role in long-term obesity management

    Real-time model-based plasma state estimation, monitoring and integrated control in TCV, ASDEX-Upgrade and ITER

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    To maintain a high-performance, long-duration tokamak plasma scenario, it is necessary to maintain desired profiles while respecting operational limits. This requires real-time estimation of the profiles, monitoring of their evolution with respect to predictions and known limits, and their active control to remain within the desired envelope. Model-based techniques are particularly suitable to tackle such problems due to the nonlinear nature of the processes and the tight coupling among the various physical variables. A suite of physics-based, control-oriented models for the core plasma proles in a tokamak is presented, with models formulated in such a way that powerful methods from the systems and control engineering community can be leveraged to design ancient algorithms. We report on new development and applications of these models for real-time reconstruction, monitoring and integrated control of plasma proles on TCV, ASDEX-Upgrade and simulations for ITER
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