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In the present work, uncertainty quantification of a venturi tube simulation with the cavitating flow is conducted based on Bayesian inference and point-collocation nonintrusive polynomial chaos (PC-NIPC). A Zwart–Gerber–Belamri (ZGB) cavitation model and RNG k-ε turbulence model are adopted to simulate the cavitating flow in the venturi tube using ANSYS Fluent, and the simulation results, with void fractions and velocity profiles, are validated with experimental data. A grid convergence index (GCI) based on the SLS-GCI method is investigated for the cavitation area, and the uncertainty error (UG) is estimated as 1.12 × 10−5. First, for uncertainty quantification of the venturi flow simulation, the ZGB cavitation model coefficients are calibrated with an experimental void fraction as observation data, and posterior distributions of the four model coefficients are obtained using MCMC. Second, based on the calibrated model coefficients, the forward problem with two random inputs, an inlet velocity, and wall roughness, is conducted using PC-NIPC for the surrogate model. The quantities of interest are set to the cavitation area and the profile of the velocity and void fraction. It is confirmed that the wall roughness with a Sobol index of 0.72 has a more significant effect on the uncertainty of the cavitating flow simulation than the inlet velocity of 0.52.

AB testing aids business operators with their decision making, and is considered the gold standard method for learning from data to improve digital user experiences. However, there is usually a gap between the requirements of practitioners, and the constraints imposed by the statistical hypothesis testing methodologies commonly used for analysis of AB tests. These include the lack of statistical power in multivariate designs with many factors, correlations between these factors, the need of sequential testing for early stopping, and the inability to pool knowledge from past tests. Here, we propose a solution that applies hierarchical Bayesian estimation to address the above limitations. In comparison to current sequential AB testing methodology, we increase statistical power by exploiting correlations between factors, enabling sequential testing and progressive early stopping, without incurring excessive false positive risk. We also demonstrate how this methodology can be extended to enable the extraction of composite global learnings from past AB tests, to accelerate future tests. We underpin our work with a solid theoretical framework that articulates the value of hierarchical estimation. We demonstrate its utility using both numerical simulations and a large set of real-world AB tests. Together, these results highlight the practical value of our approach for statistical inference in the technology industry.

Using eye-tracking field experiments, we examine the dynamics underlying consumers' attention-allocation behaviors in online search, with focus on attention adjustment, attention renewal, and equilibrium seeking. In particular, we probed into how consumers' e-commerce search behaviors vary when they are exposed to an advertisement during a search and when they are not. The findings from the two separate experiments suggest that consumers' attention span decreases exponentially, instead of linearly, as they maneuver from the top to the bottom of a search result webpage. The total number of available options significantly influences the speed and pattern of attention decay. However, attention decay does not simply move in the direction of depletion but can be refreshed and renewed upon encountering attention-diverting ad stimuli. Although ad stimuli are often considered distracting and worthless, they can produce positive effects when positioned in the middle of a search results listing, where a consumer's attention resources are rejuvenated by ads. Finally, because of consumers' propensity to seek equilibrium, attention decay occurs more rapidly after, rather than before, attention renewal. We extend the literature on the mere categorization effect by investigating how ad stimuli structurally separate search choices into mental categories and diminish on-going attention decay patterns.

Recently, the tribological properties of graphene have been intensively examined for potential applications in micro- and nano-mechanical graphene-based devices. Here, we report that the tribological properties can be easily altered via simple chemical modifications of the graphene surface. Friction force microscopy measurements show that hydrogenated, fluorinated, and oxidized graphenes exhibit, 2-, 6-, and 7-fold enhanced nanoscale friction on their surfaces, respectively, compared to pristine graphene. The measured nanoscale friction should be associated with the adhesive and elastic properties of the chemically modified graphenes. Density-functional theory calculations suggest that, while the adhesive properties of chemically modified graphenes are marginally reduced down to ~30 %, the out-of-plane elastic properties are drastically increased up to 800 %. Based on these findings, we propose that nanoscale friction on graphene surfaces is characteristically different from that on conventional solid surfaces; stiffer graphene exhibits higher friction, whereas a stiffer three-dimensional solid generally exhibits lower friction. The unusual friction mechanics of graphene is attributed to the intrinsic mechanical anisotropy of graphene, which is inherently stiff in plane, but remarkably flexible out of plane. The out-of-plane flexibility can be modulated up to an order of magnitude by chemical treatment of the graphene surface. The correlation between the measured nanoscale friction and the calculated out-of-plane flexibility suggests that the frictional energy in graphene is mainly dissipated through the out-of-plane vibrations, or the flexural phonons of graphene.

Intratumor heterogeneity (ITH) stands as one of the main difficulties in the treatment of colorectal cancer (CRC) as it causes the development of resistant clones and leads to heterogeneous drug responses. Here, 12 sets of patient‐derived organoids (PDOs) and cell lines (PDCs) isolated from multiple regions of single tumors from 12 patients, capturing ITH by multiregion sampling of individual tumors, are presented. Whole‐exome sequencing and RNA sequencing of the 12 sets are performed. The PDOs and PDCs of the 12 sets are also analyzed with a clinically relevant 24‐compound library to assess their drug responses. The results reveal unexpectedly widespread subregional heterogeneity among PDOs and PDCs isolated from a single tumor, which is manifested by genetic and transcriptional heterogeneity and strong variance in drug responses, while each PDO still recapitulates the major histologic, genomic, and transcriptomic characteristics of the primary tumor. The data suggest an imminent drawback of single biopsy‐originated PDO‐based clinical diagnosis in evaluating CRC patient responses. Instead, the results indicate the importance of targeting common somatic driver mutations positioned in the trunk of all tumor subregional clones in parallel with a comprehensive understanding of the molecular ITH of each tumor. There is an imminent drawback of patient‐derived organoid‐based clinical diagnosis from single biopsy in evaluating colorectal cancer patient responses. The data suggest the importance of targeting ancestral somatic driver mutations positioned in the trunk of all tumor subregional clones in parallel with a comprehensive understanding of the molecular intratumor heterogeneity of each tumor in order to defy potential drug resistance.

This paper reports the design of a magnetic-geared permanent magnet synchronous motor (MG-PMSM) for a 45 kW tram traction system based on high torque density. In the case of the existing tram driving system, due to mechanical reduction gear and induction motor, it causes power transmission loss, low efficiency, and difficulty in lightweight. To solve this problem, research on the MG-PMSM, which combines a contactless magnetic gear with a high-power-density PMSM, is being actively conducted. This motor has a double rotor structure, and the inner rotor, including permanent magnet, and the outer rotor composed of pole-pieces rotate at different mechanical speeds. However, it is hard to design a tram driving system with a high torque density within limited conditions, because only one rotor in MG-PMSM is used as an output. In addition, there is no study conducted from basic design to final design, including gear ratio and topology selection in MG-PMSM for tram. Therefore, this paper presents the design process of MG-PMSM with high torque density to be applied to the 45 kW–class tram driving system. After designing the magnetic gear part that increases torque and efficiency by selecting an appropriate topologies-and-gear ratio that meets the constraints, the final finite elements method (FEM) model and electromagnetic field analysis results were derived by considering the number of poles and the number of slots. Through this, we confirmed that it is superior in output characteristics compared to the existing induction motor + mechanical gear.

A recent study reported the rapid growth of SiC single crystals of ~1.5 mm/h using high-purity SiC sources obtained by recycling CVD-SiC blocks used as materials in semiconductor processes. This method has gained attention as a way to improve the productivity of the physical vapor transport (PVT) method, widely used for manufacturing single crystal substrates for power semiconductors. When recycling CVD-SiC blocks by crushing them for use as sources for growing SiC single crystals, the properties and the particle size distribution of the material differ from those of conventional commercial SiC powders, making it necessary to study their effects. Therefore, in this study, SiC single crystals were grown using the PVT method with crushed CVD-SiC blocks of various sizes as the source material, and the growth behavior was analyzed. Simulation results of the temperature distribution in the PVT system confirmed that using large, crushed blocks as the SiC source material generates a greater temperature gradient within the source compared to conventional commercial SiC powder, making it advantageous for rapid growth processes. Additionally, when the large, crushed blocks were vertically aligned, good crystal quality was experimentally achieved at high growth rates, even under non-optimized growth conditions.

Background Skeletal muscle mass was negatively associated with metabolic syndrome prevalence in previous cross-sectional studies. The aim of this study was to investigate the impact of baseline skeletal muscle mass and changes in skeletal muscle mass over time on the development of metabolic syndrome in a large population-based 7-year cohort study. Methods A total of 14,830 and 11,639 individuals who underwent health examinations at the Health Promotion Center at Samsung Medical Center, Seoul, Korea were included in the analyses of baseline skeletal muscle mass and those changes from baseline over 1 year, respectively. Skeletal muscle mass was estimated by bioelectrical impedance analysis and was presented as a skeletal muscle mass index (SMI), a body weight-adjusted appendicular skeletal muscle mass value. Using Cox regression models, hazard ratio for developing metabolic syndrome associated with SMI values at baseline or changes of SMI over a year was analyzed. Results During 7 years of follow-up, 20.1% of subjects developed metabolic syndrome. Compared to the lowest sex-specific SMI tertile at baseline, the highest sex-specific SMI tertile showed a significant inverse association with metabolic syndrome risk (adjusted hazard ratio [AHR] = 0.61, 95% confidence interval [CI] 0.54–0.68). Furthermore, compared with SMI changes < 0% over a year, multivariate-AHRs for metabolic syndrome development were 0.87 (95% CI 0.78–0.97) for 0–1% changes and 0.67 (0.56–0.79) for > 1% changes in SMI over 1 year after additionally adjusting for baseline SMI and glycometabolic parameters. Conclusions An increase in relative skeletal muscle mass over time has a potential preventive effect on developing metabolic syndrome, independently of baseline skeletal muscle mass and glycometabolic parameters.

This paper is a comparative analysis study on topologies of magnetic geared motors for the application of railway vehicle traction systems. The magnetic geared motor (MGM) is a system in which a magnetic gear and a permanent magnet synchronous motor (PMSM) are mechanically combined, and it consists of a dual rotor that rotates at different speeds. Due to these characteristics, it has the advantages of high-power density and lightweight compared to the existing traction system. However, since the input/output relationship and electromagnetic field characteristics of this motor are completely different depending on topology, it is important to select an appropriate topology according to the application. Recently, some studies have been conducted to reflect this in industry or electric vehicles, but there is no study as a traction motor for urban railway vehicles. Therefore, in this paper, the FEM model was presented by selecting the MGM topology suitable for railway vehicles. Also, it was verified through a miniature model experiment for the corresponding topology.

This paper presents the simplified equation of skew for pole-pieces of dual-rotor permanent magnet synchronous motor combined with magnetic gear (DR-PMSM) for railway vehicles. Generally, in the case of a permanent magnet synchronous motor (PMSM), the skew is applied to the rotor to reduce the cogging torque. In the case of DR-PMSM, it is structurally or productively more advantageous to apply skew to the pole-pieces (outer rotor) than the inner rotor. However, this method is mathematically complicated and the study on it is insufficient compared to the conventional PMSM. Therefore, this paper introduces simplified equations of optimal pole-pieces skew and the peak to peak of cogging torque according to the skew angle.