China's Energy Security Strategy

Yiming He 한국국제정치학회 2007 한국국제정치학회 학술대회 발표논문집 Vol.- No.-

Lightweight design for the aluminum alloy-carbon fiber hybrid structure of the EMU car body

Yiming Shangguan,Wenjing Wang,Anrui He,Wenjun Ma,Honglei Tian 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

This paper presents an innovative electric multiple unit (EMU) car body lightweight design approach that integrates structural and material optimizations. The structural lightweight design was carried out by using a sub-frame-based method and the non-dominated genetic algorithm II. The plate thicknesses of 28 car body components were chosen as the optimization design variable. The lightweight material design was realized by replacing the aluminum alloy with composite material. The two-dimensional Hashin criterion was used to analyze and validate the strength of the composite driver’s cab. Results show that after size optimization, the structure weight of the vehicle was reduced from 10964 kg to 8661 kg, which was 21.01 % less than the initial configuration. This modular lightweight design strategy for EMU car body optimization offers valuable insights that could be taken into account in future EMU car body designs.

Lightweight Single Image Super-Resolution Convolution Neural Network in Portable Device

( Jin Wang ),( Yiming Wu ),( Shiming He ),( Pradip Kumar Sharma ),( Xiaofeng Yu ),( Osama Alfarraj ),( Amr Tolba ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.11

Super-resolution can improve the clarity of low-resolution (LR) images, which can increase the accuracy of high-level compute vision tasks. Portable devices have low computing power and storage performance. Large-scale neural network super-resolution methods are not suitable for portable devices. In order to save the computational cost and the number of parameters, Lightweight image processing method can improve the processing speed of portable devices. Therefore, we propose the Enhanced Information Multiple Distillation Network (EIMDN) to adapt lower delay and cost. The EIMDN takes feedback mechanism as the framework and obtains low level features through high level features. Further, we replace the feature extraction convolution operation in Information Multiple Distillation Block (IMDB), with Ghost module, and propose the Enhanced Information Multiple Distillation Block (EIMDB) to reduce the amount of calculation and the number of parameters. Finally, coordinate attention (CA) is used at the end of IMDB and EIMDB to enhance the important information extraction from Spaces and channels. Experimental results show that our proposed can achieve convergence faster with fewer parameters and computation, compared with other lightweight super-resolution methods. Under the condition of higher peak signal-to-noise ratio (PSNR) and higher structural similarity (SSIM), the performance of network reconstruction image texture and target contour is significantly improved.

Nonlinear dynamic analysis of cutting head-rotor-bearing system of the roadheader

Zhilong Huang,Zhongchao Zhang,Yiming Li,Guiqiu Song,Yang He 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In order to study the dynamic characteristics of cutting head and cantilever system, a nonlinear dynamic model with a 13 degrees of freedom (13-DOF) lateral torsional coupled cutting head-rotor-bearing system (CHRBS) is established. The nonlinear coupled factors of spline clearance and bearing contact force are mainly considered, the dynamic analysis of CHRBS under time-varying load is carried out. The results show that there is no positive correlation between the cutting rock thickness and the states of chaotic motion and quasiperiodic motion. The system is in the two states mentioned above when in low speed region. With the increase of rotational speed, the chaotic motion becomes periodic motion. When the hardness of rock is lower, increasing rotational speed can reduce the vibration of the system, and the cutting thickness can be increased to improve the productivity and lump rock rate. As the hardness of rocks increases, the coupled system shows complex dynamic characteristics when the rotational speed changes from low to high, and the vibration increased. When cutting hard rock, the cutting speed should be increased. However, when the speed is too high, the cutting torque of system becomes smaller. In the case of cutting hard rock, reasonable rotational speed should be chosen between improving stability and increasing cutting force. The dynamic analysis results provide strong support for the vibration reduction and dynamic design of roadheader.

Influence of Water on the Fracture Process of Marble with Acoustic Emission Monitoring

Jun Zhu,Jianhui Deng,Yiming Huang,Zhiliang He 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.7

Water has a great influence on rock fracture process, and it is necessary to explore the activity of cracks for saturated rocks at key stress points. By uniaxial compression test and acoustic emission (AE) tests, four key points of stress-strain curve for dry and saturated marble specimens are determined. Those four key stress points include: crack closure stress (point A), crack initiation stress (point B), crack damage stress (point C) and peak stress (point D). By analyzing dominant frequencies and amplitude of AE waveforms of the whole loading process and in the vicinity of key points, the fracture process of samples was studied. The results show that there are two concentrations of dominant frequency bands in both dry and saturated marble, and the ranges of dominant frequency bands of the saturated seem wider. Due to the existence of water, the number and energy of AE waveforms decrease relatively during the whole test. This phenomenon indicates that water enhances the ductility and creep characteristics of rock. The appearance of lots of AE waveform signals with low dominant frequency is the precursor information of intense crack propagation and failure for dry rock, and the effects of water increased the number of micro-tensile failures for saturated rock in the vicinity of each key point. From point A, point B, point C to point D, the proportions of H-type bands in the vicinity of each key point for dry rock show a trend of increasing - decreasing - sharply decreasing, while those for saturated rock follow the law of increasing - decreasing - increasing.

Static Stability Analysis of Single-Layer Reticulated Spherical Shell with Kiewitt-Sunflower Type

Peng Yu,Weijing Yun,Stéphane Bordas,Sheng He,Yiming Zhou 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.5

In this study, we use a large-scale parameter analysis and linear regression method to characterize the static stability of Kiewitt-sunfl ower-type single-layer reticulated spherical shell. Based on more than 15,000 numerical cases of elastic–plastic load–displacement process, and the investigations on the infl uence of buckling and instability mode, rise-span and ringnumbers ratio, effi ciency of the structure, load distribution, support conditions, size of the initial geometric imperfection and distribution patterns are proceeded. We summarize the key eff ect for stable performance of structure, and develop the formulation to calculate the ultimate capacity of stability. The results show that Kiewitt-sunfl ower type single-layer reticulated spherical shell is sensitive to defect, and diff erent distribution patterns of geometry defect lead to diff erent structural buckling. The ultimate stability bearing capacity can be improved by increasing the rise-span and ring-numbers ratio. The asymmetrical load distribution has little eff ect on the stability. The most unfavorable eigenmode is arbitrary, and it is generally not the lowest order. We summarize the key eff ect for stable performance of structure, and develop the formulation to calculate the ultimate capacity of stability.

Atrial fibrillation in critically ill patients who received prolonged mechanical ventilation: a nationwide inpatient report

( Zhen Lin ),( Hedong Han ),( Wei Guo ),( Xin Wei ),( Zhijian Guo ),( Shujie Zhai ),( Shuai Li ),( Yiming Ruan ),( Fangyuan Hu ),( Dongdong Li ),( Jia He ) 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.6

Background/Aims: To evaluate temporal trends of atrial fibrillation (AF) prevalence in critically ill patients who received prolonged mechanical ventilation (MV) in the United States. Methods: We used the 2008 to 2014 National Inpatient Sample to compute the weighted prevalence of AF among hospitalized adult patients on prolonged MV. We used multivariable-adjusted models to evaluate the association of AF with clinical factors, in-hospital mortality, hospitalization cost, and length of stay (LOS). Results: We identified 2,578,165 patients who received prolonged MV (21.27% of AF patients). The prevalence of AF increased from 14.63% in 2008 to 24.43% in 2014 (p for trend < 0.0001). Amongst different phenotypes of critically ill patients, the prevalence of AF increased in patients with severe sepsis, asthma exacerbation, congestive heart failure exacerbation, acute stroke, and cardiac arrest. Older age, male sex, white race, medicare access, higher income, urban teaching hospital setting, and Western region were associated with a higher prevalence of AF. AF in critical illness was a risk factor for in-hospital death (odds ratio, 1.13; 95% confidence interval, 1.11 to 1.15), but in-hospital mortality in critically ill patients with AF decreased from 11.6% to 8.3%. AF was linked to prolonged LOS (2%, p < 0.0001) and high hospitalization cost (4%, p < 0.0001). LOS (-1%, p < 0.0001) and hospitalization cost (-4%, p < 0.0001) decreased yearly. Conclusions: The prevalence of comorbid AF is increasing, particularly in older patients. AF may lead to poorer prognosis, and high-quality intensive care is imperative for this population.

Microwave heating assisted synthesis of novel SnSe/g-C3N4 composites for effective photocatalytic H2 production

Pengfei Chen,Xiaoquan Dai,Pingxing Xing,Xinyue Zhao,Qingle Zhang,Shifeng Ge,Jianxiao Si,Leihong Zhao,Yiming He 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

Novel SnSe/g-C3N4 photocatalysts were one-step synthesized via a microwave heating assisted process in35 min with SnSe and melamine as precursors. The as-synthesized SnSe/g-C3N4 worked very well in H2evolution via photocatalysis. Under simulated sunlight, the best SnSe/g-C3N4 sample displayed a H2-production velocity of 1064 mmol g 1 h 1, which is 1.8 folds faster than that of neat g-C3N4. Similarpromotion effect was also observed under visible light. To reveal the nature behind the highphotoactivity, a thorough investigation was performed. XRD and XPS experiments proved the binaryconstitution of the composite. DRS experiment demonstrated that the addition of SnSe improved thephotoabsorption performance. N2-adsorption analysis showed that the SnSe/g-C3N4 photocatalystpresented similar surface area as g-C3N4. TEM experiments showed that some bulk SnSe werespontaneously decomposed to nanoparticles andfinely dispersed in g-C3N4 during the microwaveheating process. These SnSe nanoparticles were believed to be the active phase and constructed aheterojunction structure with g-C3N4, resulting in the enhanced charge separation. This conclusion wasconsidered as the key factor leading to the high H2-evolution performance and was further confirmed bythe PL, EIS, and PC experiments. The present work provides a feasible and rapid method for theconstruction of g-C3N4 based photocatalysts.