Showing papers by "Vrije Universiteit Brussel published in 2022"

Wind turbine drivetrains: state-of-the-art technologies and future development trends

Abstract: Abstract. This paper presents the state-of-the-art technologies and development trends of wind turbine drivetrains – the system that converts kinetic energy of the wind to electrical energy – in different stages of their life cycle: design, manufacturing, installation, operation, lifetime extension, decommissioning and recycling. Offshore development and digitalization are also a focal point in this study. Drivetrain in this context includes the whole power conversion system: main bearing, shafts, gearbox, generator and power converter. The main aim of this article is to review the drivetrain technology development as well as to identify future challenges and research gaps. The main challenges in drivetrain research identified in this paper include drivetrain dynamic responses in large or floating turbines, aerodynamic and farm control effects, use of rare-earth material in generators, improving reliability through prognostics, and use of advances in digitalization. These challenges illustrate the multidisciplinary aspect of wind turbine drivetrains, which emphasizes the need for more interdisciplinary research and collaboration.

A framework for ensemble modelling of climate change impacts on lakes worldwide: the ISIMIP Lake Sector

Abstract: Abstract. Empirical evidence demonstrates that lakes and reservoirs are warming across the globe. Consequently, there is an increased need to project future changes in lake thermal structure and resulting changes in lake biogeochemistry in order to plan for the likely impacts. Previous studies of the impacts of climate change on lakes have often relied on a single model forced with limited scenario-driven projections of future climate for a relatively small number of lakes. As a result, our understanding of the effects of climate change on lakes is fragmentary, based on scattered studies using different data sources and modelling protocols, and mainly focused on individual lakes or lake regions. This has precluded identification of the main impacts of climate change on lakes at global and regional scales and has likely contributed to the lack of lake water quality considerations in policy-relevant documents, such as the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC). Here, we describe a simulation protocol developed by the Lake Sector of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) for simulating climate change impacts on lakes using an ensemble of lake models and climate change scenarios for ISIMIP phases 2 and 3. The protocol prescribes lake simulations driven by climate forcing from gridded observations and different Earth system models under various representative greenhouse gas concentration pathways (RCPs), all consistently bias-corrected on a 0.5∘ × 0.5∘ global grid. In ISIMIP phase 2, 11 lake models were forced with these data to project the thermal structure of 62 well-studied lakes where data were available for calibration under historical conditions, and using uncalibrated models for 17 500 lakes defined for all global grid cells containing lakes. In ISIMIP phase 3, this approach was expanded to consider more lakes, more models, and more processes. The ISIMIP Lake Sector is the largest international effort to project future water temperature, thermal structure, and ice phenology of lakes at local and global scales and paves the way for future simulations of the impacts of climate change on water quality and biogeochemistry in lakes.

Experimental and numerical thermal analysis of a lithium-ion battery module based on a novel liquid cooling plate embedded with phase change material

Abstract: In this paper, the thermal behavior of a battery module based on a novel liquid cooling plate (LCP) is experimentally and numerically studied. The cooling plate is embedded with phase change material (PCM), and it is named a hybrid LCP as it provides a combination of active (liquid) and passive (PCM) cooling methods for battery with a modular design. The cooling performance of the proposed thermal management system is investigated for three cases, including low currents with pure passive cooling, medium currents with triggered liquid cooling, and high currents with constant liquid cooling. Additionally, the potential of the PCM in preventing the switched-off module from a fast temperature drop in cold environments is examined. The thermal performance of the hybrid LCP is numerically compared with a conventional aluminum LCP of the same dimension. The results indicate that pure passive cooling is able to keep the module temperature in the desired range at low currents. The hybrid LCP reduces the energy consumption of the pump by around 40% during the triggered liquid cooling. The cold temperature investigations show that the hybrid LCP is able to keep the module 5.5 °C higher than a module with aluminum LCP after 1.5 h in a cold environment of 0 °C, that can reduce the energy needed for warming the batteries up. Based on the results of this research, the proposed hybrid LCP could be a promising solution for utilizing PCMs in combination with liquid cooling for battery thermal management in electric vehicles.

Real-time motion control of robotic manipulators for safe human–robot coexistence

Abstract: This paper introduces a computationally efficient control scheme for safe human–robot interaction. The method relies on the Explicit Reference Governor (ERG) formalism to enforce input and state constraints in real-time, thus ensuring that the robot can safely operate in close proximity to humans. The resulting constrained control method can steer the robot arm to the desired end-effector pose (or a steady-state admissible approximation thereof) in the presence of actuator saturation, limited joint ranges, speed limits, static obstacles, and humans. The effectiveness of the proposed solution is supported by theoretical results and numerous experimental validations on the Franka Emika Panda robotic manipulator, a commercially available collaborative 7-DOF robot arm.

E-Selectin-Dependent Inflammation and Lipolysis in Adipose Tissue Exacerbate Steatosis-to-NASH Progression via S100A8/9.

Abstract: Background & Aims Nonalcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease, characterized by steatosis and hallmark liver neutrophil infiltration. NASH also is associated with adipose tissue inflammation, but the role of adipose tissue inflammation in NASH pathogenesis remains obscure. The aim of this study was to investigate the interplay between neutrophil recruitment in adipose tissue and the progression of NASH. Methods A mouse model of NASH was obtained by high-fat diet (HFD) feeding plus adenovirus-Cxcl1 overexpression (HFD+AdCxcl1). Genetic deletion of E-selectin (Sele) and treatment with an S100A9 inhibitor (Paquinimod) were investigated using this model. Results By analyzing transcriptomic data sets of adipose tissue from NASH patients, we found that E-selectin, a key adhesion molecule for neutrophils, is the highest up-regulated gene among neutrophil recruitment-related factors in adipose tissue of NASH patients compared with those in patients with simple steatosis. A marked up-regulation of Sele in adipose tissue also was observed in HFD+AdCxcl1 mice. The HFD+AdCxcl1-induced NASH phenotype was ameliorated in Sele knockout mice and was accompanied by reduced lipolysis and inflammation in adipose tissue, which resulted in decreased serum free fatty acids and proinflammatory adipokines. S100A8/A9, a major proinflammatory protein secreted by neutrophils, was highly increased in adipose tissue of HFD+AdCxcl1 mice. This increase was blunted in the Sele knockout mice. Therapeutically, treatment with the S100A9 inhibitor Paquinimod reduced lipolysis, inflammation, and adipokine production, ameliorating the NASH phenotype in mice. Conclusions E-selectin plays an important role in inducing neutrophil recruitment in adipose tissue, which subsequently promotes inflammation and lipolysis via the production of S100A8/A9, thereby exacerbating the steatosis-to-NASH progression. Targeting adipose tissue inflammation therefore may represent a potential novel therapy for treatment of NASH.

Imaging of treatment response and minimal residual disease in multiple myeloma: state of the art WB-MRI and PET/CT

Abstract: Bone imaging has been intimately associated with the diagnosis and staging of multiple myeloma (MM) for more than 5 decades, as the presence of bone lesions indicates advanced disease and dictates treatment initiation. The methods used have been evolving, and the historical radiographic skeletal survey has been replaced by whole body CT, whole body MRI (WB-MRI) and [18F]FDG-PET/CT for the detection of bone marrow lesions and less frequent extramedullary plasmacytomas.Beyond diagnosis, imaging methods are expected to provide the clinician with evaluation of the response to treatment. Imaging techniques are consistently challenged as treatments become more and more efficient, inducing profound response, with more subtle residual disease. WB-MRI and FDG-PET/CT are the methods of choice to address these challenges, being able to assess disease progression or response and to detect "minimal" residual disease, providing key prognostic information and guiding necessary change of treatment.This paper provides an up-to-date overview of the WB-MRI and PET/CT techniques, their observations in responsive and progressive disease and their role and limitations in capturing minimal residual disease. It reviews trials assessing these techniques for response evaluation, points out the limited comparisons between both methods and highlights their complementarity with most recent molecular methods (next-generation flow cytometry, next-generation sequencing) to detect minimal residual disease. It underlines the important role of PET/MRI technology as a research tool to compare the effectiveness and complementarity of both methods to address the key clinical questions.

More than the sum of its parts: Considering interdependencies in the life cycle material flow and environmental assessment of demountable buildings

Abstract: On the long term, buildings could initiate less material flows and have improved environmental performance if they are designed for future disassembly and reuse. However, material flows in the building life cycle are difficult to map, especially those initiated by material replacements and at end-of-life. The calculation formula for the number of replacements in buildings in the Life Cycle Assessment standard EN 15978 neglects the effect such replacements may have on the surrounding interdependent building parts, and hence fails to capture the potential benefits of Design for Disassembly. In light of this shortcoming, we propose a method to model the flows of building parts initiated by the disassembly of a building, both during operational and end-of-life stages. This modeling method considers aspects of structural stability, accessibility, and the use of detachable connections. It offers a bottom-up time-based Material Flow Analysis of an entire building which can be integrated in a Life Cycle Assessment. We apply our method on a pavilion and compare the method results to the those obtained with EN 15978, considering nine design options. The life cycle environmental impact estimated with our method is up to 162% larger than the impacts calculated with EN 15978 for a pavilion with non-detachable connections, which demonstrates the importance of this design parameter. Our method can be of interest to researchers, Life Cycle Assessment and Life Cycle Costing auditors, architecture, engineering and construction professionals, urban miners and any other actors interested in the design of demountable buildings.

Associating Alzheimer’s disease pathology with its cerebrospinal fluid biomarkers

Abstract: Alzheimer's disease CSF biomarkers 42 amino acid long amyloid-β peptide (Aβ1-42), total tau protein (T-tau), and tau protein phosphorylated at threonine 181 (P-tau181) are considered surrogate biomarkers of Alzheimer's disease pathology, and significantly improve diagnostic accuracy. Their ability to reflect neuropathological changes later in the disease course is not well characterized. This study aimed to assess the potential of CSF biomarkers measured in mid to late stage Alzheimer's disease to reflect post-mortem neuropathological changes. Individuals were selected from two autopsy cohorts of Alzheimer's disease patients in Antwerp and Amsterdam. Neuropathological diagnosis was performed according to the updated consensus National Institute on Aging-Alzheimer's Association guidelines, which includes quantification of amyloid-β plaque, neurofibrillary tangle, and neuritic plaque load. CSF samples were analysed for Aβ1-42, T-tau, and P-tau181 by ELISA. One hundred and fourteen cases of pure definite Alzheimer's disease were included in the study (mean age 74 years, disease duration 6 years at CSF sampling, 50% females). Median interval between CSF sampling and death was 1 year. We found no association between Aβ1-42 and Alzheimer's disease neuropathological change profile. In contrast, an association of P-tau181 and T-tau with Alzheimer's disease neuropathological change profile was observed. P-tau181 was associated with all three individual Montine scores, and the associations became stronger and more significant as the interval between lumbar puncture and death increased. T-tau was also associated with all three Montine scores, but in individuals with longer intervals from lumbar puncture to death only. Stratification of the cohort according to APOE ε4 carrier status revealed that the associations applied mostly to APOE ε4 non-carriers. Our data suggest that similar to what has been reported for Aβ1-42, plateau levels of P-tau181 and T-tau are reached during the disease course, albeit at later disease stages, reducing the potential of tau biomarkers to monitor Alzheimer's disease pathology as the disease progresses. As a consequence, CSF biomarkers, which are performant for clinical diagnosis of early Alzheimer's disease, may not be well suited for staging or monitoring Alzheimer's disease pathology as it progresses through later stages.

Do C-tactile afferents go to sleep? A potential role for somatosensory stimulation in sleep regulation

Abstract: Co-sleeping facilitates physiological regulation and interpersonal trust between partners. Here we discuss the possibility that this effect depends on C-tactile (CT) afferents—a class of unmyelinated mechanosensory cutaneous skin nerves that underlie both parasympathetic regulation and the rewarding neurochemistry of endogenous opioids and oxytocin. The literature reports that insomnia-related problems result from an overall difficulty to de-arouse. Moreover, sleep loss is prevalent in somatosensory-poor contexts such as in Isolated, Confined and Extreme (ICE) contexts (e.g. Antarctica, Covid-19 pandemic). On this backdrop, we propose two mechanisms by which CT-afferents may moderate a touch-sleep association, that is, a long-term mechanism-dependent on epigenetic programming in the course of child development and a short-term mechanism-dependent on a CT-modulation of autonomic and endocrine processes.

Histograms of oriented mosaic gradients for snapshot spectral image description

Abstract: This paper presents a feature descriptor using Histogram of Oriented Mosaic Gradient (HOMG) that extracts spatial-spectral features directly from mosaic spectral images. Spectral imaging utilizes unique spectral signatures to distinguish objects of interest in the scene more discriminatively. Snapshot spectral cameras equipped with spectral filter arrays (SFAs) capture spectral videos in real time, making it possible to detect/track fast moving targets based on spectral imaging. How to effectively extract the spatial-spectral feature directly from the mosaic spectral images acquired by snapshot spectral cameras is a core issue for detection/tracking. So far, there is a lack of comprehensive and in-depth research on this issue. To this end, this paper proposed a new spatial-spectral feature extractor for mosaic spectral images. The proposed scheme finds two forms of SFA neighborhood (SFAN) to construct a feature extractor suitable for any SFA structure. Exploiting the spatial-spectral correlation in two SFANs, we design six mosaic spatial-spectral gradient operators to compute spatial-spectral gradient maps (SGMs). HOMG descriptors are constructed using the magnitude and orientation of SGMs. The effectiveness and generalizability of the proposed method have been verified with object tracking experiments. Compared to the state-of-the-art feature descriptors, HOMG ranked first on two datasets captured with snapshot spectral camera with different SFAs, achieving a gain of 3.9% and 5.9% in average success rate over the second-ranked feature.