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Suitable housing conditions for ageing in place and receiving health services at home:The value of a composite index
No full textGO-Plan:A goal-oriented method for FAIRification planning
No full textThe FAIR principles provide guidance on improving the Findability, Accessibility, Interoperability, and Reusability of digital resources. Since the publication of the principles, several workflows have been proposed to support the process of making data FAIR (FAIRification). However, to respect the uniqueness of different communities, both the principles and the available workflows have been deliberately designed to remain agnostic in terms of standards, tools, and implementation choices. Consequently, FAIRification needs to be properly planned, and implementation details must be discussed with stakeholders and aligned with FAIRification objectives. To support this need, this paper describes GO-Plan, a method for identifying and refining FAIRification objectives. Leveraging on best practices from requirements and ontology engineering, the method aims at incrementally elaborating the most obvious aspects of the domain (e.g. the initial set of elements to be collected) into complex and comprehensive objectives. The definition of clear objectives enables stakeholders to communicate effectively and make informed implementation decisions, such as defining achievement criteria for distinct principles and identifying relevant metadata to be collected. GO-Plan has been validated in multiple discussion sessions with experts on FAIR, in an application to a real use case and in two hands-on tutorials with end-users
Interior Point Methods Are Not Worse than Simplex
No full textWe develop a new “subspace layered least squares” interior point method (IPM) for solving linear programs. Applied to an n-variable linear program in standard form, the iteration complexity of our IPM is up to an O(n 1.5 log n) factor upper bounded by the straight-line complexity (SLC) of the linear program. This term refers to the minimum number of segments of any piecewise linear curve that traverses the wide neighborhood of the central path, a lower bound on the iteration complexity of any IPM that follows a piecewise linear trajectory along a path induced by a self-concordant barrier. In particular, our algorithm matches the number of iterations of any such IPM up to the same factor O(n 1.5 log n). As our second contribution, we show that the SLC of any linear program is upper bounded by 2 n(1+o (1)), which implies that our IPM's iteration complexity is at most exponential. This is in contrast to existing iteration complexity bounds that depend on either bit complexity or condition measures; these can be unbounded in the problem dimension. We achieve our upper bound by showing that the central path is well-approximated by a combinatorial proxy we call the max central path, which consists of 2n shadow vertex simplex paths. Our upper bound complements the lower bounds of Allamigeon et al. [SIAM J. Appl. Algebra Geom., 2 (2018), pp. 140-178] and Allamigeon, Gaubert, and Vandame [No self-concordant barrier interior point method is strongly polynomial, 2022], who constructed linear programs with exponential SLC. Finally, we show that each iteration of our IPM can be implemented in strongly polynomial time. Along the way, we develop a deterministic algorithm that approximates the singular value decomposition of a matrix in strongly polynomial time to high accuracy, which may be of independent interest.</p
Near-Zero Parasitic Shift Rectilinear Flexure Stages Based on Coupled n-RRR Planar Parallel Mechanisms
No full textFlexure-based linear stages have become prevalent in precision engineering; however, most designs suffer from parasitic shifts that degrade positioning accuracy. Conventional solutions to mitigate these parasitic motions often compromise support stiffness, reduce motion range, and increase structural complexity. This study presents a novel family of flexure-based rectilinear-motion stages using coupled n-RRR planar parallel mechanisms, achieving extremely low parasitic shifts while addressing the forementioned limitations. Four design variants are selected and analyzed via Finite Element Method (FEM) simulations, evaluating parasitic shifts, stroke, and support stiffness. The most precise configuration, a 4-RRR rectilinear stage having kinematic chains coupled via two Watt linkages, exhibits a lateral shift smaller than 0.258 µm and an in-plane parasitic rotation smaller than 12.6 µrad over a 12 mm stroke. Experimental validation using a POM prototype confirms the high positioning precision and support stiffness properties. In addition, a silicon prototype incorporating thermally preloaded buckling beams is investigated to reduce its translational stiffness. Experimental results show a translational stiffness reduction of 98% in the monostable configuration and 112% in the bistable configuration (i.e., negative stiffness), without support stiffness reduction. These results highlight the potential of the proposed mechanisms for a wide range of precision applications, offering a scalable and high-accuracy solution for micro- and nano-positioning systems.</p
Predicting debris flow pathways using volume-based thresholds for effective risk assessment
No full textInvestigating the preferential flow path of a debris flow is crucial for quantifying the risk and developing mitigation strategies. Here, we examined 66 debris flows from the Western Ghats in India employing Rapid Mass Movement Simulation (RAMMS)::Debris Flow software to understand the kinematics of run-out. Our analysis revealed that the debris flow run-out in the study area follow two main routes: 60 along the existing stream channels (SC) and six following the steepest hill slope (SH). We further simulated these debris flows to identify their drivers, and derived a threshold that distinguishes between SC and SH-type debris flows. Our results indicate that the debris flow volumes greater than 7072 cu. m is SH-type, whereas those with smaller volumes are more likely to follow SC paths. The model’s accuracy was validated against field observations, achieving a success rate of 93% for SH-type flows and 85% for SC
Random walk approach to predict electromagnetic emissions for multiple power electronic converters
No full textThis thesis addresses the increasing Electromagnetic Compatibility (EMC) challenges posed by multiple Power Electronic (PE) converters operating simultaneously within a network. As current EMC standards predominantly focus on single-device evaluation, a significant research gap exists in modelling and predicting aggregate electromagnetic interference from multiple converters. The research proposes a new application of Pearson’s Random Walk (PRW) theory to characterise Common Mode (CM) electromagnetic emissions in multi-converter configurations.The investigation demonstrates that Pearson’s Random Walk provides an effective statistical framework for modelling electromagnetic emissions from multiple PE converters, where traditional deterministic approaches have proven inadequate. The model is based on the assumption that the sole variable under control is the switching-on time of the converters. The model employs vectors that represent the phase of waveforms being produced by each converter, associating converter switch-on times with vector angles to predict aggregated electromagnetic interference. This approach was verified through both simulation studies of eight identical converters and experimental measurements with three DC/DC converters.Statistical verification through empirical and theoretical cumulative distribution function (cdf) confirmed the model’s validity regardless of harmonic number. Furthermore, the research presents the first explicit computation of the probability that electromagnetic interference is reduced in a multiconverter configuration compared to a single-converter arrangement. Results indicate that whilst electromagnetic interference reduction is possible, this probability diminishes with an increasing number of converters.The developed methodology offers manufacturers and network operators a robust framework for predicting worst-case electromagnetic emissions in multi-converter systems, thereby addressing requirements specified in current electromagnetic compatibility directives. This contribution advances the standardisation efforts of the IEC CISPR Working Group 4 concerning the impact of increased device quantities on electromagnetic compatibility
Capacity and delay analysis of multi-hop wireless networks
Get PDFThe capacity and delay of wireless multi-hop networks are key performance indicators. They are needed in the design of such networks, and are also useful to assess how well applications can run over such networks. However, finding analytical expressions for capacity and delay for a wireless multi-hop network with an arbitrary topology is hard. In this work, a two-step approach is followed to derive expressions for the maximum achievable capacity and the minimum achievable delay in wireless multi-hop networks. These expressions are valid for fixed, conflict-free time-slot scheduling among the nodes, and when each nodes of the network has always packets to send to each of its neighbours. In the first step, expressions for the capacity and delay of the elementary topologies ’string’ and ’star’ are derived, and in the second step, these results are combined to derive the capacity and delay values for a network with an arbitrary topology. This two-step approach is applied to two types of wireless multi-hop networks: those whose nodes have an omni-directional antenna, and those whose nodes have an electronically steerable directional (beam-steering) antenna. Using this approach, we find that the capacity of a path on the network is not a decreasing function of the total number of nodes in the network, as mostly found in literature, but rather a decreasing function of the number of neighbours of the nodes on the path. The results show that the derived maximum value for the capacity (and minimum value for the delay) in networks with beam-steering antennas is larger (lower) than that for networks with omni-directional antennas as more efficient scheduling is possible for the former. The derived analytic expressions for capacity and delay are valuable for the relative comparison of the performance of wireless multi-hop networks.</p
Behavioral Fluctuation in Disorders of Consciousness:A Retrospective Analysis
Get PDFObjectives: To assess the frequency of behavioral fluctuations in patients with prolonged disorders of consciousness (DoC), characterize the stability of consciousness ratings, and characterize the stability of behavioral signs of consciousness.Design: Prospective observational analysis. Setting: Specialized DoC program in an inpatient rehabilitation facility and a long-term acute care hospital.Participants: Patients in a vegetative state/unresponsive wakefulness state, minimally conscious state, and emerging from a minimally conscious state followed weekly by the Coma Recovery Scale-Revised (CRS-R) between 28 and 90days postinjury (N=241).Main Outcome Measures: Change in CRS-R subscale scores and consciousness ratings. Results: Behavioral fluctuation was observed in >80% of patients and was most common in the CRS-R motor subscale and least common in the communication subscale (83% and 54% of patients experienced ≥1 fluctuation over the 3wk study period, respectively, with a 1-point change observed most frequently). Among patients who were conscious at baseline assessment, 25% were subsequently rated as unconscious at least once. Localization to pain and object manipulation were the most stable signs of consciousness, recurring at least 3 times after the first occurrence in ≥97% of the sample. Reproducible command-following and intelligible verbalization were the least stable, recurring at least 3 times after the first occurrence in ≤27% of the sample.Conclusions: Patients with prolonged DoC who undergo serial assessment demonstrate a high rate of fluctuation in behavioral signs of consciousness. These findings highlight that repeated assessments are essential in this population, both to capture the highest level of consciousness and to help distinguish spontaneous fluctuation from response to treatment in interventional studies.</p
Deep Merge:Deep-Learning-Based Region Merging for Remote Sensing Image Segmentation
Get PDFImage segmentation represents a fundamental step in analyzing very high-spatial-resolution (VHR) remote sensing imagery. Its objective is to partition an image into segments that best match with geo-objects. However, the diverse appearances of geospatial objects often lead to interobject homogeneity and intraobject heterogeneity. Existing segmentation methods often struggle to accurately segment geo-objects with varying shapes and scales. To address these challenges, we propose DeepMerge, a novel method that integrates deep learning and region adjacency graphs (RAGs) to accurately segment complete geo-objects in large VHR images. DeepMerge begins with an initial over-segmentation of the image and then iteratively merges similar regions to achieve complete geo-object segmentation. A deep learning model is employed to learn the similarity between adjacent superpixel pairs. This approach only requires labels indicating whether adjacent superpixels belong to the same geo-object eliminating the need for object-level annotations, enabling weakly supervised segmentation. A cross-scale module is incorporated to capture multiscale information, enhancing the representation of superpixels. In addition, the feature distances between neighboring super-pixels are deemed as scale parameters (thresholds) to control the merging procedure, thus yielding an interpretable, predictable, stable, and optimal scale parameter 0.5. DeepMerge can achieve high segmentation accuracy in a weakly supervised manner, which is validated on large-scale remote sensing images of 0.55-m resolution covering an area of 5660 km2. The experimental results demonstrate that DeepMerge achieves the highest F value (0.9552) and the lowest total error (TE) (0.0827), accurately segmenting geo-objects of varying sizes and outperforming all competing methods.</p