Analytical Formulation of the Jacobian Matrix for Non-linear Calculation of the Forced Response of Turbine Blade Assemblies with Wedge Friction Dampers

A fundamental issue in turbomachinery design is the dynamical stress assessment of turbine blades. In order to reduce stress peaks in the turbine blades at engine orders corresponding to blade natural frequencies, friction dampers are employed. Blade response calculation requires the solution of a set of non-linear equations originated by the introduction of friction damping. Such a set of non-linear equations is solved using the iterative numerical Newton-Raphson method. However, calculation of the Jacobian matrix of the system using classical numerical finite difference schemes makes frequency domain solver prohibitively expensive for structures with many contact points. Large computation time results from the evaluation of partial derivatives of the non-linear equations with respect to the displacements. In this work a methodology to compute efficiently the Jacobian matrix of a dynamic system having wedge dampers is presented. It is exact and completely analytical. The proposed methods have been successfully applied to a real intermediate pressure turbine (IPT) blade under cyclic symmetry boundary conditions with underplatform wedge dampers. Its implementation showed to be very effective, and allowed to achieve relevant time savings without loss of precision

Study of e+e−→ppˉe^+e^- \rightarrow p\bar{p} in the vicinity of ψ(3770)\psi(3770)

Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $\psi(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}$, $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $\phi = (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $\phi = (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $\psi(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow \psi(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb

흰쥐 유암의 estradiol 의존성 암성장에 따른 steroid 수용체 함량과 효소활성의 변화

To study the nature of tumor growth and regression, the mammary cancer model in Sprague-Dawley rats, induced by N-nitrosomethylurea(NMU) was analyzed with a view of biochemical response to physiological modification of host estradiol system, such as ovariectomy, tamoxifen treatment or estradiol reinjection. The growth and regression of the tumors were monitored by the tumor size variation in response to the treatment. The surgical removal of estradiol generation system such as ovariectomy and the medical treatment of estradiol antagonist, tamoxifen, markedly decreased the tumor size within two weeks, while the replenishment of estradiol by intraperitoneal reinjection stimulated the tumor growth. With these changes of tumor size, the efficiency of the functional hormonal apparatus was checked by determination of the contents of the estradiol and progesterone receptor in the cytosol and nuclear fractions, respectively. The receptor analysis showed that the contents of the cytoplasmic estradiol and progesterone receptor varied directly in response to estradiol state of the host namely, decreased level at reduced tumor volume and increased level at tumor-stimulated state. The changing patterns of the contents of the nuclear estradiol and progesterone receptors were similar to those of the cytoplasmic ones. In relation with the changes of receptor contents, the radical-related enzymes were monitored for their activities such as peroxidase, catalase, superoxide dismutase and glutathione transferase. Among them only the peroxidase activities showed the positive correlation with the estradiol receptor contents. These results indicated that the growth and regression of the mammary tumors could be deeply related with the receptor status of estradiol system and the activities of peroxidase

The associations between screen time and mental health in adolescents: a systematic review

Abstract Background Adolescents have extensive use of screens and, they have common complains related to mental health. Here a systematic review was done to understand the association between screen time and adolescent’s mental health. Method This review was conducted in compliance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses – PRISMA. An update search was performed in January 2023 with the following keywords: “screen time,“ “adolescent,“ and “mental health” on PubMed, PsycINFO and Scopus databases. Results 50 articles were included, most have found associations between screen exposure and mental health in adolescents. The most used device by adolescents was the smartphone and the use on weekdays was associated with diminished mental well-being. Social media use was negatively associated with mental well-being and, in girls, associated at higher risk for depression. Conclusion Excessive screen time in adolescents seems associated with mental health problems. Given the profusion and disparity of the results, additional studies are needed to clarify elements such as the screen content or the interaction of adolescents with different screen devices. Systematic review registration: PROSPERO CRD42022302817

A borate decorated anion-immobilized solid polymer electrolyte for dendrite-free, long-life Li metal batteries

Abrupt Li dendrite growth and the safety hazards caused by liquid electrolytes are generally acknowledged as major technical barriers for the practical application of Li metal batteries. Solid polymer electrolytes (SPEs) are promising to overcome these obstacles, but suffer from rigidity-conductivity inconsistency, ununiform ion distribution and inferior interfacial compatibility. Herein, an anion-immobilized SPE using vinylene carbonate as the rigid polymer backbone and flexible ether oxygen chains containing anion-trapping boron moieties is proposed, which facilitates the Li+ transport and adjusts the ion distribution. This ingenious design along with facile in situ preparation effectively integrates a favorable Young's modulus (2.41 GPa), high ionic conductivity (9.11 x 10(-4) S cm(-1) at 25 degrees C) and a high Li+ transference number (0.68), as well as achieving a stable solid electrolyte interface layer. As a result, these integrative properties enable dendrite-free LiFePO4/Li batteries with excellent rate capacity (8C, 98.3 mA h g(-1)) and superior long-term cyclability over 600 cycles at 30 degrees C, providing a new strategy for safe and high-energy all-solid-state energy storage systems

Measurement of the D--->K^-\pi^+ strong phase difference in \psi(3770)--->D^0\antiD^0

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