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عضویت
فهرست مطالب نویسنده:

d. liu

  • R. Xu, W. Xu, D. Liu, S. Pan, J. Zhu, Y. Shen, C. Wang*, H. Shen
    Background

    We aimed to explore the application value of low-dose computed tomography (LDCT) combined with serum tumor markers in the diagnosis of early non-small cell lung cancer (NSCLC).

    Materials and Methods

    The clinical data of 176 patients suspected of early NSCLC screened from March 2017 to April 2022 were retrospectively collected. The diagnostic values of LDCT, serum tumor markers, and LDCT combined with serum tumor markers for early NSCLC were explored.

    Results

    There were diverse imaging characteristics of early NSCLC, dominated by solid lesions, followed by part-solid nodules, but non-solid nodules were rare. The levels of serum carcinoembryonic antigen, cytokeratin 19 fragment antigen 21-1 and neuron specific enolase in patients with early NSCLC were higher than those in patients with benign lesions (P<0.05). LDCT combined with serum tumor markers had a higher Kappa coefficient than LDCT and serum tumor markers, indicating that it had the highest consistency with pathological diagnosis results (P<0.05). Both the sensitivity and accuracy of LDCT combined with serum tumor markers were higher than those of LDCT and serum tumor markers (P<0.05).

    Conclusion

    LDCT combined with serum tumor markers can significantly improve the diagnostic sensitivity and accuracy for early NSCLC and the consistency with pathological diagnosis results, and effectively reduce misdiagnosis and missed diagnosis.

    Keywords: Computed Tomography, Early Diagnosis, Non-Small Cell Lung Cancer, Serum, Tumor Markers
  • D. Liu, X. Miao *, Z. Zhang, J. Yang, T. Yuan, R. Song
    The interior noise caused by the pantograph area is greater than that caused by other areas, and the impact of this pantograph area becomes more significant as the speed of high-speed trains increases, especially above 350 km/h. This study proposes an active jet method for pantograph cavities to control noise at the source. First, a predictive model for the interior noise of pantograph carriages was established by jointly adopting large eddy simulation–statistical energy analysis methods. Then, numerical simulations were conducted to determine the external noise sources and interior sound pressure level at different speeds (300, 350, 400, and 450 km/h). Finally, active jets at different speeds (97.2, 111.1, 125, and 140 m/s) were used to analyze the reduction in interior noise. Results showed that the active jet method decreased the average overall sound pressure level of the acoustic cavity in the horizontal plane. When the train speed reached 450 km/h, the optimal reduction in interior noise was approximately 7.5 dB in the horizontal plane for both the standing and sitting postures. The proposed method can efficiently reduce interior noise in the pantograph area.
    Keywords: Active jet, Interior noise, Large eddy simulation, Pantograph carriage, Statistical energy analysis
  • M. Zhao, D. Liu *, J. Hou, X. Zhang, S. Li
    As an important control element in steam heating piping systems, the safety and stability of inverted bucket steam valves determine the reliable operation of the system. Therefore, it is necessary to investigate the acoustic mechanism of inverted bucket steam valves. Aiming at the difficulty of numerical simulation in accurately predicting the aerodynamic noise of inverted bucket steam valves, this paper proposes a new method for simulating the aerodynamic noise of inverted bucket steam valves based on multiband analysis (LES). The flow field of the inverted bucket steam valve is numerically simulated using the LES method to obtain wall pressure pulsation information and fluid velocity pulsation information, which are used as excitation sources for acoustic simulation. The characteristics of dipole and quadrupole sound sources were obtained by applying the FW-H method and experimentally verified. The results show that a new multifrequency band analysis method for inverted bucket steam valves is effective by comparing the numerical simulation results, in which the dipole source dominates in the low-frequency band, in the medium frequency range, the quadrupole source outperforms the dipole source, but in the high frequency range, the quadrupole source is dominant. The experimental results are in good agreement with the simulation results, and the correctness of the numerical simulation is confirmed by the fact that there is less than a 3% difference between the findings of the numerical simulation and the experimental data.
    Keywords: valve, Acoustical, Frequency division, Dipole, quadrupole, Sound source characteristics
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