Sensitivity Analysis Based on Polynomial Chaos Expansions and Its Application in Ship Uncertainty-Based Design Optimization

In order to truly reflect the ship performance under the influence of uncertainties, uncertainty-based design optimization (UDO) for ships that fully considers various uncertainties in the early stage of design has gradually received more and more attention. Meanwhile, it also brings high dimensionality problems, which may result in inefficient and impractical optimization. Sensitivity analysis (SA) is a feasible way to alleviate this problem, which can qualitatively or quantitatively evaluate the influence of the model input uncertainty on the model output, so that uninfluential uncertain variables can be determined for the descending dimension to achieve dimension reduction. In this paper, polynomial chaos expansions (PCE) with less computational cost are chosen to directly obtain Sobol' global sensitivity indices by its polynomial coefficients; that is, once the polynomial of the output variable is established, the analysis of the sensitivity index is only the postprocessing of polynomial coefficients. Besides, in order to further reduce the computational cost, for solving the polynomial coefficients of PCE, according to the properties of orthogonal polynomials, an improved probabilistic collocation method (IPCM) based on the linear independence principle is proposed to reduce sample points. Finally, the proposed method is applied to UDO of a bulk carrier preliminary design to ensure the robustness and reliability of the ship

High performance carbon-coated hollow Ni12P5 nanocrystals decorated on GNS as advanced anodes for lithium and sodium storage

Transition-metal phosphides have been considered as promising anode materials for rechargeable secondary batteries owing to their low cost and high capacity. However, low electronic conductivity and poor stability limit their further development. Herein, we have designed a template-free refluxing method for synthesizing tailored carbon-coated hollow Ni 12 P 5 nanocrystals in situ grown on reduced graphene oxide nanosheets (denoted as Ni 12 P 5 @C/GNS). The hollow structure can accommodate volume expansion and shorten the ion transfer path. The GNS loading and carbon shell can efficiently prevent Ni 12 P 5 from aggregating and improve the electronic conductivity. As an anode of Li-ion batteries (LIBs), the hollow Ni 12 P 5 @C/GNS composite displays an excellent discharge specific capacity of 900 mA h g -1 at a current density of 100 mA g -1 after 100 cycles and outstanding rate capability. Furthermore, it also shows a good Na storage capability with a reversible capacity of 235 mA h g -1 at 100 mA g -1 . Therefore, our work demonstrates that this hollow Ni 12 P 5 @C/GNS composite has great potential for Li/Na storage

NURBS-Based Parametric Design for Ship Hull Form

Recently, the NURBS technique has been widely used in the 3D design software for ships. However, in most research, the NURBS technique is only applied to the mathematical representation of hull curves and surfaces, and the parametric deformation of hull surfaces based on geometric feature parameters is less understood. The aims of this paper are to establish the parametric design process of hull surfaces through the classification of geometric feature parameters and the design of feature curves, apply the NURBS technique to the parametric geometric modeling of hull curves and surfaces, and finally achieve the parametric deformation of hull surfaces driven by geometric feature parameters and develop the parametric deformation software. Taking the Series 60 ship as an example, we first analyze the hull geometric features and parameters, then design the longitudinal feature curves and cross-section curves based on the NURBS technique and establish the correlation between them, and finally generate the smooth hull surface by the skinning technique to achieve the parametric geometric deformation of the Series 60 ship. The research in this paper shows that the smoothness of the surfaces generated by the NURBS-based parametric design method is good. Additionally, the extracted feature parameters have a clear geometric meaning and can automatically generate hull forms to meet the design requirements quickly and effectively, which has some practical engineering value

Application of Basis Functions for Hull Form Surface Modification

Basis functions are key in constructing interpolation equations in hull surface modification based on radial basis functions (RBF) interpolation. However, few have studied the selection of basis functions in depth. By comparing several typical basis functions through a theoretical analysis and two-dimensional modification examples, the Wendland ψ3,1 (W) function is selected. The advantages of hull form surface modification based on W function interpolation are further validated through a case study. Finally, the modification method is used to optimize a trimaran model. An optimal hull form with fair lines is obtained, and its wave-making resistance coefficient and total resistance are reduced by 8.3% and 3.8%, respectively, compared to those of the original model. These findings not only further illustrate that the W function is relatively suitable for hull form surface modification, but also validate the feasibility and value of the RBF interpolation-based surface modification method in engineering practice

Disability and self-reported adverse drug events among patients with chronic diseases

© 2020, Springer Nature Switzerland AG. Objective: Very few studies have examined the association between self-reported adverse drug events (ADEs) and the presence of disability in patients with chronic diseases. The purpose of this study was to investigate the relationship between disability and self-reported ADEs in a population with chronic diseases in the community setting in Korea. Methods: Data were obtained from the Korean Health Panel from 2014 to 2016, from which 5382 adults aged ≥ 30 years who received any drug to treat a chronic disease were selected. The dependent variable was defined as a self-reported ADE related to a chronic-disease drug. Disability was measured by self-reported vision problems, hearing problems, cognitive impairment, chewing problems, and activity limitation. The data were analyzed using panel logistic regression. Results: In 2016, 5.07% of participants self-reported an ADE related to a chronic-disease drug. The likelihood of a patient self-reporting an ADE depended on various sociodemographic factors, health status including disabilities, and polypharmacy. Specific risk factors for ADEs included age, vision problems, chewing problems, activity limitations, and polypharmacy. Subgroup analyses showed that the risk factors of hypertension, diabetes, and hyperlipidemia had slightly different effects on self-reporting of ADEs. Conclusions: Disabilities, such as vision problems, chewing problems, and activity limitation, were significantly related to self-reported ADEs in chronic-disease patients in the community setting

NURBS-Based Parametric Design for Ship Hull Form

Recently, the NURBS technique has been widely used in the 3D design software for ships. However, in most research, the NURBS technique is only applied to the mathematical representation of hull curves and surfaces, and the parametric deformation of hull surfaces based on geometric feature parameters is less understood. The aims of this paper are to establish the parametric design process of hull surfaces through the classification of geometric feature parameters and the design of feature curves, apply the NURBS technique to the parametric geometric modeling of hull curves and surfaces, and finally achieve the parametric deformation of hull surfaces driven by geometric feature parameters and develop the parametric deformation software. Taking the Series 60 ship as an example, we first analyze the hull geometric features and parameters, then design the longitudinal feature curves and cross-section curves based on the NURBS technique and establish the correlation between them, and finally generate the smooth hull surface by the skinning technique to achieve the parametric geometric deformation of the Series 60 ship. The research in this paper shows that the smoothness of the surfaces generated by the NURBS-based parametric design method is good. Additionally, the extracted feature parameters have a clear geometric meaning and can automatically generate hull forms to meet the design requirements quickly and effectively, which has some practical engineering value

Numerical Investigation of Global Ice Loads of Maneuvering Captive Motion in Ice Floe Fields

During escort and convoy operations, icebreakers are often required to maneuver to open up channels or adjust routes due to the prevalence of ice floe conditions in Arctic routes. This study aimed to investigate the global ice load characteristics of the maneuvering captive motions, including constant turning motion, pure yaw motion, and pure sway motion, of the icebreaker Xue Long, using a combination of the discrete element method (DEM) and drag model. First, the method was verified using simulating Araon model tests from the Korea Institute of Ocean Science and Technology (KIOST). In addition, the maneuvering captive motions of the Xue Long model were simulated at varying turning radii, drift angles, and sway and yaw periods, which are typical but currently poorly studied maneuvering motions. Overall, the results of the study showed that the method is able to reproduce the coupling effect of the ship–ice–water system by considering ship–ice interaction and ice resistance, where the mean deviation and maximum deviation of ice resistance are 9.45% and 13.3%, respectively. The influences of the turning radius, drift angle, and sway and yaw period on the ice resistance and transverse force characteristics were studied and analyzed via ship–ice interactions. The present study provides a prediction tool for the assessment of ship maneuvering performance to assist the hull line development and model testing of icebreakers

Transcriptomic Analysis of the Porcine Endometrium during Embryo Implantation

In pigs, successful embryo implantation is an important guarantee for producing litter size, and early embryonic loss occurring on day 12–30 of gestation critically affects the potential litter size. The implantation process is regulated by the expression of numerous genes, so comprehensive analysis of the endometrium is necessary. In this study, RNA sequencing (RNA-Seq) technology is used to analyze endometrial tissues during early pregnancy. We investigated the changes of gene expression between three stages (day 12, 18, and 25) by multiple comparisons. There were 1557, 8951, and 2345 differentially expressed genes (DEGs) revealed between the different periods of implantation. We selected several genes for validation by the use of quantitative real-time RT-PCR. Bioinformatic analysis of differentially expressed genes in the endometrium revealed a number of biological processes and pathways potentially involved in embryo implantation in the pig, most noticeably cell proliferation, regulation of immune response, interaction of cytokine-cytokine receptors, and cell adhesion. These results showed that specific gene expression patterns reflect the different functions of the endometrium in three stages (maternal recognition, conceptus attachment, and embryo implantation). This study identified comprehensive transcriptomic profile in the porcine endometrium and thus could be a foundation for targeted studies of genes and pathways potentially involved in abnormal endometrial receptivity and embryo loss in early pregnancy