Computationally-Efficient Thermal Modeling Techniques for Electric Machines

Electric machines are widely used in industry, ranging from as large as 700Mw generators used in Three Gorges in Yichang, China, to as small as brushless DC motors used in your computer hard drives. For some areas, such as automotive powertrain design, accurate and computationally-efficient models for electric machines are in great demand since they can play important roles as either real-time observers or in vehicle simulations. In this dissertation, computationally-efficient thermal and electromagnetic models for electric machines are developed. In particular, a thermal convection model to capture air region heat convection considering air density variation and slotting effects on stator surface is developed and analyzed; and an electromagnetic model to calculate AC winding resistance of different winding configurations is proposed and integrated. With the developed techniques, thermal and electromagnetic performance can be accurately and efficiently estimated. Furthermore, this dissertation has also conducted a comparative study, which shows the advantages of using thermal models for online loss estimation for electric machines over the conventionally-used electrical model. The conclusions and results of this study provide useful tools for online loss estimators with model uncertainty.PHDElectrical and Computer EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/168030/1/yuanying_1.pd

The Fungal CYP51s: Their Functions, Structures, Related Drug Resistance, and Inhibitors

CYP51 (Erg11) belongs to the cytochrome P450 monooxygenase (CYP) superfamily and mediates a crucial step of the synthesis of ergosterol, which is a fungal-specific sterol. It is also the target of azole drugs in clinical practice. In recent years, researches on fungal CYP51 have stepped into a new stage attributing to the discovery of crystal structures of the homologs in Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus. This review summarizes the functions, structures of fungal CYP51 proteins, and the inhibitors targeting these homologs. In particular, several drug-resistant mechanisms associated with the fungal CYP51s are introduced. The sequences and crystal structures of CYP51 proteins in different fungal species are also compared. These will provide new insights for the advancement of research on antifungal agents

MDDL: A Framework for Reinforcement Learning-based Position Allocation in Multi-Channel Feed

Nowadays, the mainstream approach in position allocation system is to utilize a reinforcement learning model to allocate appropriate locations for items in various channels and then mix them into the feed. There are two types of data employed to train reinforcement learning (RL) model for position allocation, named strategy data and random data. Strategy data is collected from the current online model, it suffers from an imbalanced distribution of state-action pairs, resulting in severe overestimation problems during training. On the other hand, random data offers a more uniform distribution of state-action pairs, but is challenging to obtain in industrial scenarios as it could negatively impact platform revenue and user experience due to random exploration. As the two types of data have different distributions, designing an effective strategy to leverage both types of data to enhance the efficacy of the RL model training has become a highly challenging problem. In this study, we propose a framework named Multi-Distribution Data Learning (MDDL) to address the challenge of effectively utilizing both strategy and random data for training RL models on mixed multi-distribution data. Specifically, MDDL incorporates a novel imitation learning signal to mitigate overestimation problems in strategy data and maximizes the RL signal for random data to facilitate effective learning. In our experiments, we evaluated the proposed MDDL framework in a real-world position allocation system and demonstrated its superior performance compared to the previous baseline. MDDL has been fully deployed on the Meituan food delivery platform and currently serves over 300 million users.Comment: 4 pages, 2 figures, accepted by SIGIR 202

Fabrication of nanoscale NiO/Ni heterostructures as electrocatalysts for efficient methanol oxidation

Nanoscale NiO/Ni heterostructures on oxygen-functionalized carbon nanotubes with low Ni loading (3–4 wt%) are fabricated by delicate thermal-annealing treatments, which are designed according to the temperature-programmed thermal analysis. Activity and stability tests demonstrate that NiO/Ni heterostructures with a stable Ni core inside an oxyhydroxide shell (in solution) exhibit enhanced stability and catalytic activity for methanol oxidation

Hydroxychloroquine improves pregnancy outcomes of women with positive antinuclear antibody spectrum test results

Background:Empirical use of Hydroxychloroquine (HCQ) in patients with positive antinuclear antibody spectrum (ANAs) test result is controversial regarding its impact on improving perinatal outcomes. This study aimed to investigate the effect of HCQ on adverse pregnancy outcomes associated with placental dysfunction in ANAs-positive patients.Methods:The study included pregnant women with positive ANAs test result from 2016 to 2020 in our center, and divided into a weakly positive and a positive group in just ANA positive patients among them. Univariate and multivariate analyses were conducted to determine the effect of HCQ on pregnancy outcomes in each subgroup. Stratified and interactive analyses were performed to assess the value of HCQ in improving pregnancy outcomes.Results:(i) A total of 261 cases were included, accounting for 30.60% of pregnancy complicated with autoimmune abnormalities, and 65.12% of them used HCQ during pregnancy. (ii) The application of HCQ significantly reduced the incidence of early-onset preeclampsia (1.18% vs. 12.09%, p = 0.040) and small-for-gestational-age infants (10.06% vs. 25.84%, p = 0.003) in the ANAs-positive population, increased birth weight (3075.87 ± 603.91 g vs. 2847.53 ± 773.73 g, p = 0.025), and prolonged gestation (38.43 ± 2.31 vs. 36.34 ± 5.45 weeks, p < 0.001). (iii) A total of 185 just ANA-positive patients were stratified according to titers. Among them, the rate of HCQ usage was significantly higher than that in the weakly positive group (81.03% vs. 58.27%, p = 0.003). (vi) Stratified univariate analysis showed that HCQ usage in the ANA-positive group could reduce the incidence of preeclampsia (2.13% vs. 27.27%, p = 0.019) and prolong gestation (38.29 ± 2.54 vs. 34.48 ± 7.68 weeks, p = 0.006). In the ANA-weakly positive group, HCQ significantly reduced the incidence of preeclampsia (6.76% vs. 28.30%, p = 0.002), early-onset preeclampsia (1.35% vs. 13.21%, p = 0.027), and small-for-gestational-age infants (7.89% vs. 35.19%, p < 0.001). Multivariate regression analysis showed that HCQ significantly reduced the incidence of preeclampsia in both groups. Intergroup interaction analysis showed no significant difference in the value of HCQ in reducing the incidence of preeclampsia between the two groups.Conclusion:ANAs positivity is an important abnormal autoimmunity type in pregnancy. HCQ can be considered as a choice for improving adverse pregnancy outcomes related to placental dysfunction, such as preeclampsia, in this population

On the Use of Large Interactive Displays to Support Collaborative Engagement and Visual Exploratory Tasks

Large interactive displays can provide suitable workspaces for learners to conduct collaborative learning tasks with visual information in co-located settings. In this research, we explored the use of these displays to support collaborative engagement and exploratory tasks with visual representations. Our investigation looked at the effect of four factors (number of virtual workspaces within the display, number of displays, position arrangement of the collaborators, and collaborative modes of interaction) on learners' knowledge acquisition, engagement level, and task performance. To this end, a user study was conducted with 72 participants divided into 6 groups using an interactive tool developed to support the collaborative exploration of 3D visual structures. The results of this study showed that learners with one shared workspace and one single display can achieve better user performance and engagement levels. In addition, the back-to-back position with learners sharing their view and control of the workspaces was the most favorable. It also led to improved learning outcomes and engagement levels during the collaboration process

Progression of radiographic fibrosis in rheumatoid arthritis-associated interstitial lung disease

Background and objectivesPreclinical interstitial lung disease (pILD) may represent the early stages of rheumatoid arthritis-associated interstitial lung disease (RA-ILD). However, the characteristics, clinical outcomes, and risk factors associated with fibrosis progression in RA-ILD, including pILD and ILD, remain poorly understood.MethodsBaseline data were compared between patients with RA-ILD and those with RA alone. Multivariate logistic regression and Cox regression analyses were performed to identify risk factors associated with the prevalence and imaging progression of RA-ILD, respectively.ResultsAmong the 371 enrolled RA patients, 32.3% had RA-ILD. Multiple logistic regression analyses identified age over 60.0 years (OR 2.22), smoking (OR 2.09), diabetes mellitus (DM) (OR 3.09), mixed connective tissue disease (MCTD) (OR 2.98), serum lactate dehydrogenase (LDH) levels exceeding 250.0 U/L (OR 6.73), and positive anti-cyclic citrullinated peptide (anti-CCP) antibody (OR 2.06) as independent risk factors for RA-ILD (p< 0.05 or 0.01). Among the 98 RA-ILD patients who underwent follow-up for a median duration of 19.1 months, 51.0% demonstrated fibrotic progression on high-resolution computed tomography (HRCT). Multiple Cox regression analysis identified DM (HR 2.03), Disease Activity Score in 28 joints-Erythrocyte Sedimentation Rate (DAS28-ESR) greater than 5.1 (HR 2.21), and baseline HRCT scores exceeding 5.0 (HR 2.30) as independent risk factors for fibrosis progression in RA-ILD (p< 0.05 or 0.01).ConclusionNearly one-third of RA patients in this cohort had prevalent pILD or ILD, and half of them demonstrated imaging progression during follow-up. DM, higher DAS28-ESR, and advanced HRCT scores were identified as independent risk factors for progressive fibrosis in RA-ILD