This contribution presents a hierarchical Bayesian filter for recursive input, state and parameter estimation using spatially incomplete and noisy output-only vibration measurements. The problem at ...hand is tailored to a dual-layered scheme, whereby the sought-after parameters are treated as random variables with a finite number of evolving states. For each one of these states an output-only Bayesian filter is employed for estimating the state and unknown input, creating thus a bank of filters, which are recursively weighted upon assimilation of the measurement data. The dynamics of parameter states are governed by an evolution strategy, which enables exploration of the parameter space and subsequent identification of the target values. The proposed scheme is numerically tested on crack identification problems using parametric reduced-order models (pROMs). The latter is a key element of the methodology in that it provides a generator of computationally efficient models, which can be evaluated at different parameter configurations, using mesh morphing. The performance of the algorithm is tested by means of simulated realistic components encountered in aerospace applications.
•A hierarchical approach for Bayesian inference of input, state and system parameters.•Fusion of Bayesian filtering with the Covariance Matrix Adaptation (CMA) evolution strategy.•Use of parametric reduced-order models for cracked systems.•Crack identification in dynamic systems using sparse output-only vibration measurements.
This paper presents a general framework for estimating the state and unknown inputs at the level of a system subdomain using a limited number of output measurements, enabling thus the component-based ...vibration monitoring or control and providing a novel approach to model updating and hybrid testing applications. Under the premise that the system subdomain dynamics are driven by the unknown (i) externally applied inputs and (ii) interface forces, with the latter representing the unmodeled system components, the problem of output-only response prediction at the substructure level can be tailored to a Bayesian input-state estimation context. As such, the solution is recursively obtained by fusing a Reduced Order Model (ROM) of the structural subdomain of interest with the available response measurements via a Bayesian filter. The proposed framework is without loss of generality established on the basis of fixed- and free-interface domain decomposition methods and verified by means of three simulated Wind Turbine (WT) structure applications of increasing complexity. The performance is assessed in terms of the achieved accuracy on the estimated unknown quantities.
Abstract The rapid growth of the wind industry has resulted in larger wind turbines with modal properties that lie in the lower frequency range, rendering accurate fatigue assessment increasingly ...important. However, high uncertainty associated with the support conditions and foundation properties can pose challenges in the condition assessment and fatigue life estimation. One approach to improve these estimates is to use structural monitoring data (e.g. from sensors mounted on the towers) to update the foundation parameters of offshore wind turbine models. However, the low identifiability of the parameters to be estimated can lead to divergent estimates across different frameworks, which, combined with uncertainty in foundation properties, can compromise remaining useful life estimates. In this work, a Bayesian model updating framework is applied to update the foundation parameters of an offshore wind turbine, and its results are compared against a deterministic framework in a numerical example. The advantages of the Bayesian framework over the deterministic framework are discussed in detail and the importance of accurately accounting for uncertainties as part of the model updating process is highlighted.
Monoterpene indole alkaloids comprise a diverse family of over 2000 plant-produced natural products. This pathway provides an outstanding example of how nature creates chemical diversity from a ...single precursor, in this case from the intermediate strictosidine. The enzymes that elicit these seemingly disparate products from strictosidine have hitherto been elusive. Here we show that the concerted action of two enzymes commonly involved in natural product metabolism-an alcohol dehydrogenase and a cytochrome P450-produces unexpected rearrangements in strictosidine when assayed simultaneously. The tetrahydro-β-carboline of strictosidine aglycone is converted into akuammicine, a Strychnos alkaloid, an elusive biosynthetic transformation that has been investigated for decades. Importantly, akuammicine arises from deformylation of preakuammicine, which is the central biosynthetic precursor for the anti-cancer agents vinblastine and vincristine, as well as other biologically active compounds. This discovery of how these enzymes can function in combination opens a gateway into a rich family of natural products.The biosynthetic pathway of preakuammicine, a monoterpene precursor of the anti-cancer agent vinblastine, has remained largely unexplored. Here, the authors provide transcriptomic and biochemical data to identify two enzymes that, in tandem, convert strictosidine to akuammicine, the stable shunt product of preakuammicine.
Summary
Structural health monitoring (SHM) has been increasingly exploited in recent years as a valuable tool for assessing performance throughout the life cycle of structural systems, as well as for ...supporting decision‐making and maintenance planning. Although a great assortment of SHM methods has been developed, only a limited number of studies exist serving as reference basis for the comparison of different techniques. In this paper, the vibration‐based assessment of a small‐scale wind turbine (WT) blade is experimentally investigated, with the aim of establishing a benchmark case study for the SHM community. The structure under consideration, provided by Sonkyo Energy as part of the Windspot 3.5 kW WT model, is tested in both healthy and damaged states under varying environmental, that is, temperature, conditions as imposed by means of a climatic chamber. This study offers a thorough documentation of the configuration of this experimental benchmark, including the types of deployed sensors, the nature of excitation and available measurements, and the investigated damage scenarios and environmental variations enforced. Lastly, an overview of the raw and processed measurement data, made available to researchers via an open access Zenodo repository, is herein provided.
Subendocardial viability ratio (SEVR), calculated through pulse wave analysis, is an index of myocardial oxygen supply and demand. Our aim was to evaluate the relationship between coronary flow ...reserve (CFR) and SEVR in 36 consecutive untreated hypertensives (aged 57.9 years, 12 males, all Caucasian) with indications of myocardial ischaemia and normal coronary arteries in coronary angiography. CFR was calculated by a 0.014-inch Doppler guidewire (Flowire, Volcano, San Diego, CA, USA) in response to bolus intracoronary administration of adenosine (30-60 μg). SEVR was calculated by radial applanation tonometry, while diastolic function was evaluated by means of transmitral flow and tissue Doppler imaging. Hypertensive patients with low CFR (n=24) compared with those with normal CFR (n=12) exhibited significantly decreased SEVR by 24.5% (P=0.002). In hypertensives with low CFR, CFR was correlated with SEVR (r=0.651, P=0.001). After applying multivariate linear regression analysis, age, left ventricular mass index, Em/Am, 24-h diastolic blood pressure (BP) and SEVR turned out to be the only independent predictors of CFR (adjusted R(2)=0.718). Estimation of SEVR by using applanation tonometry may provide a reliable tool for the assessment of coronary microcirculation in essential hypertensives with indications of myocardial ischaemia and normal coronary arteries.
Very recent work reported that patients can monitor their heartbeat at home and specify their heart conditions by means of a millimetre wave radar, but there exist serious limitations because the ...radar sensor is sensitive to significant body motions that cause Doppler frequency shifts. Such limitations do not exist when using a recently constructed portable photoplethysmography (PPG) electronic device, which gives results comparable with a standard electrocardiogram (ECG). Since all portable modern devices such as smart phones tablets etc support Bluetooth communication that allows easy and direct communication with our PPG device, it may give us remote sensing heart related information. Applying natural time analysis to data simultaneously collected with an ECG system and a PPG device and using two complexity measures quantifying the entropy change in natural time under time reversal, a distinction is achieved between healthy (H) individuals and congestive heart failure (CHF) patients. Employing a support vector machine classifier for CHF discrimination to a total of 99 individuals (including 67 CHF), we obtained 97.7% sensitivity. In a follow up study challenging results are obtained since during the subsequent period six individuals died, who remarkably obeyed additional complexity measures that may distinguish sudden cardiac death individuals from CHF.
Summary
This paper constitutes the numerical companion of the experimental work on vibration‐based monitoring of a small‐scale wind turbine (WT) blade. In this second part, a numerical benchmark is ...established for condition assessment of a Windspot 3.5‐kW WT blade. The aim is to supplement the companion experimental work with a physical model exposed to diverse operational conditions, loading scenarios, and damage patterns that are not easily explorable and controllable in the laboratory. To this end, a finite element (FE) model of the considered blade is developed and subjected to a number of artificial damage scenarios, which are dynamically tested under both environmental and operational variability. The paper offers a detailed description of the numerical benchmark and the underlying assumptions, as well as the spectrum of operational conditions, the measured quantities, and the wind load model. Finally, we provide an overview and demonstration of the stand‐alone application for time history analysis and generation of synthetic vibration data, which is made available via an open‐access code in Sonkyo‐Benchmark repository.
Plants and fungi have provided, or inspired, key pharmaceuticals for global health challenges, including cancer, heart disease, dementia, and malaria, and are valued as traditional medicines ...worldwide. Global demand for medicinal plants and fungi has threatened certain species, contributing to biodiversity loss and depletion of natural resources that are important for the health of humanity. We consider the evolving role of plants and fungi in global healthcare as new challenges to human health and to biodiversity arise. We present current and emerging scientific approaches, to uncover and preserve nature‐based health solutions for the future, through harmonization with biodiversity conservation strategies.
Societal Impact Statement
Plants and fungi have provided, or inspired, key pharmaceuticals for global health challenges, including cancer, heart disease, dementia, and malaria, and are valued as traditional medicines worldwide. Global demand for medicinal plants and fungi has threatened certain species, contributing to biodiversity loss and depletion of natural resources that are important for the health of humanity. We consider the evolving role of plants and fungi in global healthcare as new challenges to human health and to biodiversity arise. We present current and emerging scientific approaches, to uncover and preserve nature‐based health solutions for the future, through harmonization with biodiversity conservation strategies.
Summary
Non‐communicable diseases, including cardiovascular disease, cancer, and diabetes, are the main causes of deaths globally, and communicable diseases such as malaria and tuberculosis affect billions of people. Plants and fungi have provided key pharmaceuticals in our armory against these global health challenges, while in some regions of the world, they continue to have a central role in healthcare systems as traditional medicines. Consequently, global demand for plants and fungi in healthcare has threatened certain medicinal species, and is a driving factor in biodiversity loss. Yet the future of therapeutics from nature is evolving. Scientific advances are enabling the untapped potential of the world's plants and fungi to be explored for their medicinal value, and to reveal other roles they may have for improving health and well‐being; this demonstrates the value of natural capital as an incentive for biodiversity conservation. Emerging technologies also offer new hope for safeguarding essential medicines for the future, by revealing more sustainable solutions for sourcing key natural products. This review discusses recent developments and future approaches for the discovery of natural products as medicines, for health and well‐being, and strategies to harmonize the therapeutic use of biodiversity with its proactive conservation through nature‐based solutions.
Plant monoterpene indole alkaloids, a large class of natural products, derive from the biosynthetic intermediate strictosidine aglycone. Strictosidine aglycone, which can exist as a variety of ...isomers, can be reduced to form numerous different structures. We have discovered a short‐chain alcohol dehydrogenase (SDR) from plant producers of monoterpene indole alkaloids (Catharanthus roseus and Rauvolfia serpentina) that reduce strictosidine aglycone and produce an alkaloid that does not correspond to any previously reported compound. Here we report the structural characterization of this product, which we have named vitrosamine, as well as the crystal structure of the SDR. This discovery highlights the structural versatility of the strictosidine aglycone biosynthetic intermediate and expands the range of enzymatic reactions that SDRs can catalyse. This discovery further highlights how a sequence‐based gene mining discovery approach in plants can reveal cryptic chemistry that would not be uncovered by classical natural product chemistry approaches.
Cryptic and unnatural natural products: A short‐chain alcohol dehydrogenase from plant producers of monoterpene indole alkaloids (C. roseus and R. serpentina) reduces strictosidine aglycone to form an alkaloid that does not correspond to any previously reported compound.
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