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  • SAGE Publications  (4)
  • 1
    Online Resource
    Online Resource
    Three-dimensional discrete element simulation of the runaway vehicle deceleration process on the arrester bed of truck escape ramps
    SAGE Publications ; 2020
    In:  Science Progress Vol. 103, No. 3 ( 2020-07)
    Details
    In: Science Progress, SAGE Publications, Vol. 103, No. 3 ( 2020-07)
    Abstract: Due to imperfect design norms and guidelines for China’s truck escape ramp, previous studies have not been able to reflect the effect of wheel subsidence process on the deceleration of runaway vehicles. A discrete element method was used to establish an aggregate discrete element and a wheel discrete element. The three-dimensional discrete element model for an aggregate-wheel combination was established based on a particle flow code in three dimensions on a software platform using the “FISH” language. The microscopic parameters of the aggregate discrete element particles and wheel discrete element particles were calibrated using a simulated static triaxial compression test and real vehicle test data, respectively. Four sets of numerical simulation tests were designed for analyzing the influence of the aggregate diameter, grade of the arrester bed, truckload, and entry speed on the wheel subsidence depth and stopping distance of runaway vehicles. The results indicate that the smaller the aggregate diameter and entry speed and the greater the truckload and grade of the arrester bed, the more easily the wheel falls into the gravel aggregate, the better the deceleration effect, and the smaller the stopping distance. As the wheel subsidence depth increases, the speed at the unit stopping distance decreases more quickly. The maximum subsidence depth mainly depends on the truckload. The research results can provide a theoretical basis for the design of the arrester bed length and the thickness of the aggregate pavement in a truck escape ramp.
    Type of Medium: Online Resource
    ISSN: 0036-8504 , 2047-7163
    URL: Article
    DOI: 10.1177/0036850420940890
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
    detail.hit.zdb_id: 128412-5
    detail.hit.zdb_id: 2199376-2
    SSG: 11
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Acoustic metamaterial composed of zigzag channel and micro-perforated plate for enhanced low-frequency sound absorption
    SAGE Publications ; 2024
    In:  Journal of Vibration and Control Vol. 30, No. 13-14 ( 2024-07), p. 2894-2903
    Details
    In: Journal of Vibration and Control, SAGE Publications, Vol. 30, No. 13-14 ( 2024-07), p. 2894-2903
    Abstract: We propose the theoretical design and experimental authentication of an ultrathin sound absorber consisting of a perforated plate and a back cavity with zigzag channels for realizing high-efficiency and broadband absorption of low-frequency sound. The dependence of the absorption performance on the structural parameters is analyzed, which suggests the possibility of decreasing the peak frequency of resonance noise absorption with equal compactness of device. Based on this, we propose a hybrid design composed of multiple structures with different parameters to effectively expand the working bandwidth, and propose to further optimize the low-frequency absorption performance by adjusting the inclined partitions in the zigzag channel. The experimental results show that nearly 100% sound absorption is obtained at the resonance frequency ( 〈 500 Hz) with an absorber 30 times thinner than the wavelength. We envision our designed sound absorber with deep-subwavelength size, broadband functionality, and easy fabrication to find wide applications in noise control engineering.
    Type of Medium: Online Resource
    ISSN: 1077-5463 , 1741-2986
    URL: Article
    DOI: 10.1177/10775463231186859
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2024
    detail.hit.zdb_id: 1306262-1
    detail.hit.zdb_id: 2070247-4
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  • 3
    Online Resource
    Online Resource
    A broadband low-frequency muffler based on neural network method and Helmholtz resonator with helical neck
    SAGE Publications ; 2023
    In:  Journal of Vibration and Control Vol. 29, No. 17-18 ( 2023-09), p. 3942-3951
    Details
    In: Journal of Vibration and Control, SAGE Publications, Vol. 29, No. 17-18 ( 2023-09), p. 3942-3951
    Abstract: In this study, a design method of broadband low-frequency muffler based on NN method and Helmholtz resonators with helical necks is proposed, which ensures almost perfect ventilation and broadband sound insulation in the low- and medium-frequency range. First, the sound insulation performance of the muffler is improved by adding a helical structure at the port. The slit Helmholtz resonator with a helical structure is able to reduce the cross-sectional area of the resonator port and increase the contact area of thermal viscosity loss, thus reducing the peak frequency of sound insulation and increasing the sound energy loss. Using finite element analysis software, the structural transmission loss is simulated. At the same time, the neural network method is used to predict the combined structure, then, the combined structure can be designed quickly and reasonably to achieve the sound insulation of medium- and low-frequency broadband. Experimental and simulation results show that in the target range of 430 Hz–2220 Hz, the overall TL exceeds 30 dB and the maximum exceeds 60 dB. In addition, when a helical structure is added, the overall pipeline remains unchanged; and when a muffler is added on the basis, the perfect ventilation effect can be achieved. The proposed structural model and the idea of rapid design lay a great foundation for the design and optimization of broadband muffler.
    Type of Medium: Online Resource
    ISSN: 1077-5463 , 1741-2986
    URL: Article
    DOI: 10.1177/10775463221107197
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 1306262-1
    detail.hit.zdb_id: 2070247-4
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  • 4
    Online Resource
    Online Resource
    The Mono-Prep system increases the detection rate of sputum smear microscopy for diagnosing tuberculosis
    SAGE Publications ; 2018
    In:  Journal of International Medical Research Vol. 46, No. 12 ( 2018-12), p. 5137-5142
    Details
    In: Journal of International Medical Research, SAGE Publications, Vol. 46, No. 12 ( 2018-12), p. 5137-5142
    Abstract: Direct sputum smear microscopy (DSSM) has a low detection rate. This study investigated whether an alternative method called Mono-Prep smear microscopy (MPSM) can enhance the diagnosis of tuberculosis in tuberculosis laboratories that perform direct smear microscopy in China. Methods A total of 117 sputum samples were collected from outpatients who attended Beijing Chest Hospital. DSSM, MPSM, solid culture, and Xpert MTB/RIF were performed on the samples. Results The positive rates of DSSM, MPSM, solid culture, and Xpert MTB/RIF were 27.4% (32/117), 40.2% (47/117), 35.9% (42/117), and 52.1% (61/117), respectively. MPSM could detect 15 more cases of tuberculosis compared with DSSM (47 vs 32) among 117 sputum samples. This represented a significantly higher positive rate and sensitivity of MPSM compared with DSSM. However, MPSM appeared to have a lower specificity (81.3%) compared with DSSM (90.7%) with the solid culture used as a standard. Conclusion Use of MPSM can increase the number of positive sputum samples, but it still needs improvement.
    Type of Medium: Online Resource
    ISSN: 0300-0605 , 1473-2300
    URL: Article
    DOI: 10.1177/0300060518792354
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 184023-X
    detail.hit.zdb_id: 2082422-1
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