479 research outputs found

    Multi-Objective Topology Optimization for Curved Arm of Multifunctional Billet Tong Based on Characterization of Working Conditions

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    A windlass driven heavy duty multifunctional billet tong was designed for large-scale forging and casting to reduce the number of auxiliary material handling devices in manufacturing workshops. To improve its mechanical performance and safety, a novel multi-objective topology optimization method for its curved arm is proposed in this paper. Firstly, the influence of different open angles and working frequencies for the curved arm was simplified to a multi-objective optimization problem. A comprehensive evaluation function was constructed using the compromise programming method, and a mathematical model of multi-objective topology optimization was established. Meanwhile, a radar chart was employed to portray the comparative measures of working conditions, the weight coefficient for each working condition was determined based on the corresponding enclosed areas, combining the stress indices, the displacement indices and the frequency indices of all working conditions. The optimization results showed that the stiffness and strength of the curved arm can be improved while its weight can be reduced by 10.77%, which shows that it is feasible and promising to achieve a lightweight design of the curved arm of a billet tong. The proposed method can be extended to other equipment with complex working conditions

    Multi-Objective Topology Optimization for Curved Arm of Multifunctional Billet Tong Based on Characterization of Working Conditions

    Get PDF
    A windlass driven heavy duty multifunctional billet tong was designed for large-scale forging and casting to reduce the number of auxiliary material handling devices in manufacturing workshops. To improve its mechanical performance and safety, a novel multi-objective topology optimization method for its curved arm is proposed in this paper. Firstly, the influence of different open angles and working frequencies for the curved arm was simplified to a multi-objective optimization problem. A comprehensive evaluation function was constructed using the compromise programming method, and a mathematical model of multi-objective topology optimization was established. Meanwhile, a radar chart was employed to portray the comparative measures of working conditions, the weight coefficient for each working condition was determined based on the corresponding enclosed areas, combining the stress indices, the displacement indices and the frequency indices of all working conditions. The optimization results showed that the stiffness and strength of the curved arm can be improved while its weight can be reduced by 10.77%, which shows that it is feasible and promising to achieve a lightweight design of the curved arm of a billet tong. The proposed method can be extended to other equipment with complex working conditions

    The mediating role of psychological capital on the association between occupational stress and depressive symptoms among Chinese physicians: a cross-sectional study

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    BACKGROUND: Although occupational stress is an identified predictor of depressive symptoms, the mechanism behind the association is not well understood. The purpose of this study was to examine how psychological capital (PsyCap), a positive psychological state, mediates the association between occupational stress and depressive symptoms among Chinese physicians. METHODS: A cross-sectional survey was conducted in Liaoning Province, China, during September–October 2010. Self-administered questionnaires including items on depressive symptoms assessed by the Center for Epidemiologic Studies Depression Scale, occupational stress assessed by the effort–reward imbalance scale and PsyCap estimated by a 24-item Psychological Capital Questionnaire, together with age, gender, marital status and education were distributed to 1300 physicians employed in large general hospitals. The final sample consisted of 998 participants. Asymptotic and resampling strategies were used to examine how PsyCap mediates the association between occupational stress and depressive symptoms. RESULTS: Both the effort/reward ratio (ERR) and overcommitment were significantly associated with depressive symptoms among male and female physicians. There was a gender difference in the mediating role of PsyCap on the occupational stress–depressive symptoms association. For male physicians, PsyCap did not mediate the association between occupational stress and depressive symptoms. For female physicians, ERR and overcommitment were negatively associated with PsyCap, and PsyCap was negatively associated with depressive symptoms. As a result, PsyCap significantly mediated the associations of ERR and overcommitment with depressive symptoms. The proportion of PsyCap mediation was 19.07% for ERR, and 24.29% for overcommitment. CONCLUSIONS: PsyCap could be a positive resource for combating depressive symptoms in Chinese physicians. In addition to reducing occupational stress, PsyCap development should be included in depression prevention and treatment strategies, especially for female physicians

    Effects of mTOR inhibitor, everolimus, on proliferation, autophagy and temozolomide sensitivity of glioma cells

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    Purpose: To study the effect of the mTOR inhibitor, everolimus, on glioma cell proliferation, autophagy, and drug sensitivity to temozolomide (TMZ).Methods: Human glioma cell lines were cultured in vitro, and the effects of different concentrations of everolimus on the proliferation of brain glial cells were determined using CCK-8 method. The effect of different concentrations of everolimus on brain glial cell levels of autophagy protein were assayed by western blot method.Results: The results of CCK-8 analysis showed that everolimus inhibited the proliferation of glial cells in a time- and concentration-dependent manner. Western blot results showed that the expression levels of autophagy proteins, LC3-II and LC3-II/I, were gradually and concentration-dependently up-regulated, while p62 protein level was gradually decreased concentration-dependently, when compared with blank control (p < 0.05). Treatment with different concentrations of TMZ alone, and in combination with everolimus for 48 h inhibited the proliferation of brain glial cells in a concentration-dependent manner, but the inhibition due to TMZ-everolimus combination was significantly higher than that of TMZ singletreatment (p < 0.05). After 48 h, the expression level of Beclin-1 increased with the ratio of LC3-II/LC-I in TMZ-everolimus group, while the expression level of p62 decreased, when compared with TMZ alone, or control (p < 0.05).Conclusion: Everolimus significantly inhibits the proliferation of glioma cells and promotes the occurrence of autophagy. Combined use of TMZ and everolimus significantly enhances the sensitivity of TMZ to glioma cells, inhibits cell proliferation, and promotes autophagy better than TMZ alone. Keywords: mTOR inhibitor, Everolimus, Glioma cells, Proliferation, Autophag

    PPGAN: Privacy-preserving Generative Adversarial Network

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    Generative Adversarial Network (GAN) and its variants serve as a perfect representation of the data generation model, providing researchers with a large amount of high-quality generated data. They illustrate a promising direction for research with limited data availability. When GAN learns the semantic-rich data distribution from a dataset, the density of the generated distribution tends to concentrate on the training data. Due to the gradient parameters of the deep neural network contain the data distribution of the training samples, they can easily remember the training samples. When GAN is applied to private or sensitive data, for instance, patient medical records, as private information may be leakage. To address this issue, we propose a Privacy-preserving Generative Adversarial Network (PPGAN) model, in which we achieve differential privacy in GANs by adding well-designed noise to the gradient during the model learning procedure. Besides, we introduced the Moments Accountant strategy in the PPGAN training process to improve the stability and compatibility of the model by controlling privacy loss. We also give a mathematical proof of the differential privacy discriminator. Through extensive case studies of the benchmark datasets, we demonstrate that PPGAN can generate high-quality synthetic data while retaining the required data available under a reasonable privacy budget.Comment: This paper was accepted by IEEE ICPADS 2019 Workshop. This paper contains 10 pages, 3 figure

    Evaluation of oral Lanzhou lamb rotavirus vaccine via passive transfusion with CD4+/CD8+ T lymphocytes

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    AbstractLanzhou Lamb derived Rotavirus (RV) Vaccine (namely LLR) for children is only used in China. Since there were no reports on evaluation of LLR, even the data of phase IV clinical trial, we proceed the evaluation of LLR through focusing on T-cell to investigate whether LLR could induce the potential function involving in protection as a vaccine. Four groups of nude mice were transfused with CD4+/CD8+ T-cells isolated from LLR-immunized (primed) and LLR-unimmunized (naĂŻve) mice via intraperitonea (i.p.) respectively. Consequently, the adoption mice were challenged with mice-origin wild rotavirus EDIM (Epizootic Diarrhea of Infant Mice) by intragastric administration. Series of fecal/serum samples were collected and viral shedding, then serum IgA/IgG and secreted IgA were assayed. Compared to the mice transfused with T lymphocytes from naĂŻve mice, the nude mice transfused with CD4+ T lymphocytes from primed mice induce fecal and serum IgA increasing more rapidly, and have a shorter duration of virus shedding too. Whereas, no significant difference in virus clearance was found between the mice transfused with CD8+ T lymphocytes isolated from primed and naĂŻve mice. Therefore, we cleared the distinct roles of transfused CD4+/CD8+ T lymphocytes for rotavirus clearance in nude mice, that the viral clearance conducted by CD4+ T lymphocytes. Meanwhile, it has ability to help induction of LLR specific immunogenicity. Comparing with the transfusion of cell from primed and naĂŻve mice, LLR can induce CD4+ T lymphocytes memory which is a potential index to reflect the immunogenicity and protection, while CD8+ T lymphocytes remove rotavirus by CTL with little memory ability

    FedBA: Non-IID Federated Learning Framework in UAV Networks

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    With the development and progress of science and technology, the Internet of Things(IoT) has gradually entered people's lives, bringing great convenience to our lives and improving people's work efficiency. Specifically, the IoT can replace humans in jobs that they cannot perform. As a new type of IoT vehicle, the current status and trend of research on Unmanned Aerial Vehicle(UAV) is gratifying, and the development prospect is very promising. However, privacy and communication are still very serious issues in drone applications. This is because most drones still use centralized cloud-based data processing, which may lead to leakage of data collected by drones. At the same time, the large amount of data collected by drones may incur greater communication overhead when transferred to the cloud. Federated learning as a means of privacy protection can effectively solve the above two problems. However, federated learning when applied to UAV networks also needs to consider the heterogeneity of data, which is caused by regional differences in UAV regulation. In response, this paper proposes a new algorithm FedBA to optimize the global model and solves the data heterogeneity problem. In addition, we apply the algorithm to some real datasets, and the experimental results show that the algorithm outperforms other algorithms and improves the accuracy of the local model for UAVs
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