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- Han, Yong, et al.
(författare)
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Finite Element Analysis of Lower Extremity Fractures in Vehicle-Pedestrian Collision
- 2011
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Ingår i: Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (Engineering and Technology Edition). - 1671-5497. ; 41:1, s. 6-11，id.1671-5479(2011)01-0006-06-
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Tidskriftsartikel (refereegranskat)abstract
- A finite element Human Body Model (HBM) of lower extremity was improved based on the geometry of human skeleton anatomy. The model consists of the pelvis, the femur, the tibia, the fibula, the patella, the foot bones, primary tendons, knee joint capsule, meniscus, and ligaments. This model is constructed using shell and solid elements also including linear spring-damper elements, it contains of 29777 nodes and 30873 elements. The whole model was validated by comparing the results of simulation with these from shearing-bending cadaver tests described in literature. Then the FE HBM of lower extremity and an existing multi-body system (MBS) human model of the pedestrian were used to reconstruct the real-world vehicle-pedestrian accident and lower limb injuries. Results of injury reconstruction show that this FE model has a good biofidelity and biomechanical response, and can be applied in research on lower limb injury mechanisms and used in the development of injury protective devices.
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| 4. |
- Lu, Zhiqin, et al.
(författare)
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Martial arts and mathematics : 武侠和数学
- 2019
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Ingår i: Mathematics Culture. ; 10, s. 104-107
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Tidskriftsartikel (refereegranskat)abstract
- 如果有一双完美的耳朵，并且受过足够的训练，那么一个人通过听觉最多能够听出一种兵器/乐器的多少细节？——从这个问题里我们似乎可以看出武侠和数学的关系。
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| 8. |
- Chen, Tao, et al.
(författare)
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Comprehensive applicability evaluation of multi-source snow depth datasets over the Tibetan Plateau
- 2022
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Ingår i: Journal of Glaciology and Geocryology. - 1000-0240. ; 44:3, s. 795-809
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Tidskriftsartikel (refereegranskat)abstract
- Snow cover over the Tibetan Plateau has an important impact on the regional climate and water cycle. At present, the existing snow cover datasets have great uncertainty across this region, so the applicability assessment is indispensable in order to make best use of the advantages and bypass the disadvantages. In this study, a comprehensive quantitative evaluation of multiple variables and multiple evaluation indicators was carried out for three snow depth datasets over the Tibetan Plateau against the meteorological station observations（OBS）. The three snow depth datasets include one passive microwave remote sensing dataset（CHE）and two reanalysis datasets（ERA5-Land and MERRA2）. The variables are the annual mean snow depth, the annual maximum snow depth, and the annual snow cover days. In addition, the evaluation indicators are seasonal cycle, climatology, maximum value, standard deviation, interannual variation, and trend. A rank score（RS）value of 0~1 is computed for each evaluation indicator of each variable, the larger value of RS indicate relatively better performance of a snow depth dataset. Assessment results imply that, comprehensively considered, MERRA2 exhibits best agreement with OBS, followed by ERA5-Land, and finally CHE. Evaluate based on the RS of each variable, MERRA2 shows better performance on annual maximum snow depth and annual snow cover days, CHE shows better performance on annual mean snow depth. Evaluate based on the RS of each evaluation indicator, CHE shows advantages in describing trend, ERA5-Land exhibits better agreement with OBS on interannual variation, and MERRA2 show better performance on the rest of the indicators including seasonal cycle, climatology, maximum value and standard deviation. The RS statistics in terms of regional average and spatial distribution show that CHE performs better in the former, and ERA5-Land performs better in the latter. On the other hand, there are obvious deficiencies in all three snow depth datasets. MERRA2 has insufficient ability to characterize the interdecadal variation in snow cover, and its qualitative results for trend in snow cover is inconsistent with OBS, the reason for the first deficiency needs to be further studied and the second deficiency may be mainly related to its simulation capability to precipitation trend. ERA5-Land significantly overestimates the snow cover over the Tibetan Plateau, this may be mostly related to its data assimilation scheme. CHE has poor ability to characterize the spatial distribution of snow cover, coarse spatial resolution of passive microwave remote sensing may be the main reason. The conclusions are only applicable to the central and eastern part of the Tibetan Plateau due to the scarcity of meteorological station in west part of the Tibetan Plateau. Based on the remote sensing and reanalysis data, there is great uncertainty in the trend of snow cover in the western part of the Tibetan Plateau. These systematic classification evaluation of the three representative snow depth datasets provides information on data selection and data refinement.
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| 9. |
- Han, Lei, et al.
(författare)
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基于飞秒激光的一维速度场测量方法
- 2022
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Ingår i: Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics. - 0253-231X. ; 43:1, s. 267-271
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Tidskriftsartikel (refereegranskat)abstract
- Femtosecond laser-induced cyano chemiluminescence uses femtosecond filaments to tag molecules in a flow field, and velocity information of the flow field can be obtained by observing the displacement of the tagged molecules within a known time. The one-dimensional (1D) emitting line contains 1D velocity field information, but only the velocity at the central point can be given because it is unable to precisely correlate the position information before and after the line moves. For this problem, we propose a 1D velocity field inversion algorithm, which can invert the velocity of the whole emitting line according to the displacement of the emitting line and its shape, and finally obtain the 1D-2C velocity field information on the line. By using the moving trajectory of multiple emitting lines we can also obtain the 2D velocity field information.
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| 10. |
- Qian, Li-Bing, et al.
(författare)
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Transmission of electrons through the conical glass capillary with the grounded conducting outer surface
- 2017
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Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 66:12
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Tidskriftsartikel (refereegranskat)abstract
- The transmission of 1.5 keV-electrons through a conical glass capillary is reported. This study aims to understand the so-called guiding effect for the negatively charged particles (e.g. electrons). The guiding mechanism is understood quite well with positively charged particles in particular highly charged ions, but not clear with electrons, i. e., even the basic scheme mediated by the existence of negative charge patches to guide the electrons is still somewhat controversial.. The study of the charging-up dynamics causing the electrons transport inside the capillary will shed light on this issue. In order to perform this, a data acquisition system has been setup to follow the time evolution of the two-dimensional angular distribution of the transmitted electrons. The electrons are detected by the multi-channel plate (MCP) detector with a phosphor screen. The image from the phosphor screen is recorded by a charge-coupled device camera. The timing signals for the detected events are extracted from the back stack of the MCP detector and recorded by the data acquisition system, synchronized with the acquired images. The electron beam has a size of 0.5 mm x 0.5 mm and a divergence of less than 0.35.. The inner diameter of the straight part of the capillary is 1.2 mm and the exit diameter is 225 mu m. A small conducting aperture of 0.3 mm in diameter is placed at the entrance of the capillary. Two-dimensional angular distribution of the transmitted electrons through conical glass capillary and its time evolution are measured. The results show that the transmission rate decreases and reaches to a constant value for the completely discharged glass capillary with time going by. The centroid of the angular distribution moves to an asymptotic value while the width remains unchanged. These transmission characteristics are different from those indicated in our previous work (2016 Acta Phys: Si n: 65 204103). The difference originates from the different manipulations of the capillary outer surface. A conducting layer is coated on the outer surface of the capillary and grounded in this work. This isolates various discharge/charge channels and forms a new stable discharge channel. The transmission rate as a function of the tilt angle shows that the allowed transmission occurs at the tilt angle limited by the geometrical factors, i. e., the geometrical opening angle given by the aspect ratio as well as the beam divergence. The transmission characteristics suggest that most likely there are formed no negative patches to facilitate the electron transmission through the glass capillary at this selected beam energy. It is different from that of highly charged ions, where the formation of the charge patches prohibits the close collisions between the following ions and guides them out of the capillary.
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