41 research outputs found

    MST-Based Semi-Supervised Clustering Using M-Labeled Objects

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    Most of the existing semi-supervised clustering algorithms depend on pairwise constraints, and they usually use lots of priori knowledge to improve their accuracies. In this paper, we use another semi-supervised method called label propagation to help detect clusters. We propose two new semi-supervised algorithms named K-SSMST and M-SSMST. Both of them aim to discover clusters of diverse density and arbitrary shape. Based on Minimum Spanning Tree's algorithm variant, K-SSMST can automatically find natural clusters in a dataset by using K labeled data objects where K is the number of clusters. M-SSMST can detect new clusters with insufficient semi-supervised information. Our algorithms have been tested on various artificial and UCI datasets. The results demonstrate that the algorithm's accuracy is better than other supervised and semi-supervised approaches

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

    A new surrogate of Fischer–Tropsch fuel and its pollution emission in gas turbine combustor

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    Abstract Based on the analysis of the combustion process of liquid fuel in the gas turbine combustor, we suggest that a comprehensive surrogate fuel should be developed according to the basic physical and chemical properties that affect the diffusion combustion process. The present study took the carbon–hydrogen mole ratio, molar weight, density, viscosity, surface tension, initial boiling point, and lower heating value, as the target properties. The optimal direction method was utilized to obtain the mixture composition ratio which has the minimum deviation on the basic physical and chemical properties compared with the Fischer–Tropsch (F‐T) fuel. This mixture, taken as the comprehensive surrogate fuel of the F‐T fuel, was composed of 15% n‐decane, 67% n‐tetradecane, 13% iso‐octane, and 5% methylcyclohexane in mole fraction. Further experiments were conducted to investigate the pollutant emissions of the F‐T fuel and the surrogate fuel in a gas turbine combustor. The experimental results showed that the surrogate fuel can well predict the EI(CO) and EI(NOx) of the F‐T fuel in the turbine combustor, and the difference in EI(UHC) is mainly influenced by the fuel evaporation property

    A Fast Lithium-Ion Battery Impedance and SOC Estimation Method Based on Two-Stage PI Observer

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    Due to the complex changes in battery state, the accurate and fast estimation of battery state of charge (SOC) is still a great challenge. Here, a fast estimation method of battery impedance and SOC based on a multi-level PI observer is proposed. The observer model reflects the change of the battery state characteristics through the dynamic impedance, and then the system compensation factor is added to the observer to dynamically adjust the parameters of the battery model. The effectiveness of the algorithm is verified by the compound dynamic stress test (DST) experiment. The results show that the introduction of the compensation factor enables the system to tolerate a certain degree of impedance fluctuation and capacity attenuation and the maximum SOC estimation error can be kept within 2%

    Review: Research on product surface quality inspection technology based on 3D point cloud

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    In recent years, machine vision has played an important role in product surface quality detection. The promotion and use of this technology have largely avoided the subjectivity caused by human detection and improved detection efficiency and accuracy. Different from the image data commonly used in machine vision, point cloud can describe the spatial structure of an object, provide more information than image data, and have the ability to expand the data to build multi-dimensional data models. Due to the strong anti-interference ability of point cloud sensors and the high accuracy of three-dimensional positioning information point cloud, nondestructive testing technology based on point cloud has received more and more attention. This paper summarizes the research progress of product surface quality detection methods based on 3D point cloud in recent years. According to different data processing methods, the detection research is divided into five categories: based on point cloud contour, based on local geometric feature, based on template matching, based on multimodal point cloud, and based on deep learning. The five methods are reviewed and summarized respectively. Finally, the key problems of each detection method and the future trend of product surface quality detection technology based on 3D point cloud are discussed

    The complete chloroplast genome sequence of Rheum tanguticum, an endangered Chinese medicinal plant (Polygonaceae)

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    Rheum tanguticum is a valuable medicinal plant endemic to the Qinghai-Tibetan Plateau. It has been listed classified under the IUCN Red List categories of Vulnerable due to the low reproductive rate and heavy exploitation. In this study, the complete chloroplast (cp) genome of R. tanguticum has been assembled using data from the whole-genome Illumina sequencing. The cp genome is 161,515 bp in size and contains two inverted repeat regions of 30,823 bp each, which is separated by a large single-copy region of 86,675 bp and a small single-copy region of 13,194 bp. The cp genome contains 87 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic analysis revealed that the cp genome of R. tanguticum was closely related to that of the R. palmatum

    Type II Homo-Type Bi<sub>2</sub>O<sub>2</sub>Se Nanosheet/InSe Nanoflake Heterostructures for Self-Driven Broadband Visible-Near-Infrared Photodetectors

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    Bi2O2Se nanosheets, an emerging ternary non-van der Waals two-dimensional (2D) material, have garnered considerable research attention in recent years owing to their robust air stability, narrow indirect bandgap, high mobility, and diverse intriguing properties. However, most of them show high dark current and relatively low light on/off ratio and slow response speed because of the large charge carrier concentration and bolometric effect, hindering their further application in low-energy-consuming optoelectronics. Herein, a homotype van der Waals heterostructure based on exfoliated n-InSe integrated with chemical vapor deposition (CVD)-grown n-Bi2O2Se nanosheets that have type II band alignment was fabricated. The efficient interfacial charge separation, strong interlayer coupling, and effective built-in electric field across the heterointerface demonstrated excellent, stable, and broadband self-driven photodetection in the range 400-1064 nm. Specifically, a high responsivity (R) of 75.2 mA·W-1 and a high specific detectivity (D*) of 1.08 × 1012 jones were achieved under 405 nm illumination. Additionally, a high R of 13.3 mA·W-1 and a high D* of 2.06 × 1011 jones were achieved under 980 nm illumination. Meanwhile, an ultrahigh Ilight/Idark ratio over 105 and a fast response time of 5.8/15 ms under 405 nm illumination confirmed the excellent photosensitivity and fast response behavior. Furthermore, R could be enhanced to 13.6 and 791 mA·W-1 under 405 and 980 nm illumination at a drain-source voltage (Vds) of 1 V, respectively, originating from a lower potential barrier. This study suggested that the Bi2O2Se nanosheet/InSe nanoflake homotype heterojunction can offer potential applications in next-generation broadband photodetectors that consume low energy and exhibit high performance.</p

    Optimizing Metasurface-Component Performance by Improving Transmittance and Phase Match of the Nanopillars

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    In the propagation phase of a dielectric metasurface, there are two important problems. Firstly, the range of transmittance of the nanopillars for a building metasurface is usually between 60% and 100%, which reduces the metasurface&rsquo;s overall transmittance and affects the uniformity of the transmitted light. Secondly, the realistic phase provided by the nanopillar cannot be matched very well with the theoretical phase at each lattice location.The phase difference (between a realistic phase and theoretical phase) may reach tens of degrees. Here, we propose an interesting method to solve these problems. With this new method, a metalens is designed in this paper. The nanopillars for building the metalens have transmittance over 0.95, which increases the metalens transmittance and improves the light uniformity. In addition, with the new method, the phase differences of all elements in the metalens can also be reduced to be below 0.05&deg;, decreasing the metalens spherical aberration dramatically. This method not only helps us to optimize the metalens but also provides a useful way for designing high-quality metasurfaces
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