Crosswind Stability of Metro Train on a High-Pier Viaduct under Spatial Gust Environment in Mountain City

Yunfei Zhang,Li Li 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12

To ensure the ride quality of metro system in mountain cities, the characteristics of the wind-train-bridge system with high-piers are studied, and the corresponding safety threshold is calculated in this paper. The improved spatial gust model considering the wind speed-up effect in mountainous terrain and spatial correlation is established. The time series of the wind loads are input to the dynamic system. The finite element method is used to model the bridge and the track, the multi-rigid-body system connected with the suspension spring and the damper is used to model each vehicle in the train. The whole process of the metro train running on the three-span high-pier viaduct is simulated. The study shows that both amplitude and frequency components of fluctuating wind have greater influence than the average wind, which can make the calculation result tend to be conservative and more conducive to analyze the vehicle running performance. Due to the comprehensive effect of the correlation of gust in spatial distribution, different vehicle parameters and aerodynamic coefficient differences, the response of each vehicle is different. The windward side of the high-pier bridge is the conservative calculation condition to evaluate the running performance. The wind barrier weakens the wind resistance of the bridge, but greatly improves the wind environment for the train. Metro train is less sensitive to increased wind speed with the wind barrier, but exceeds the limit under the same condition without any measures. When wind speed reaches 30 and 32 m/s, the ride comfort and running safety cannot be guaranteed respectively. The corresponding value for with single-side and bilateral barrier are 0.063 g and 0.061 g, decrease by 37% and 39% than that without barrier, and the value with two barriers are 0.216 and 0.211, decrease by 73% and 74%.

Low-frequency noise inside metro: contribution analysis and noise control treatment

Yunfei Zhang,Li Li,Zheng Bu,Cunzhen Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.6

Low-frequency interior noise tends to tire passengers and affect their health, the wheel/rail vibration and rolling noise are crucial noise sources. For a metro vehicle, the wheel/rail vibration transmits to the car body through the primary and secondary suspensions, causes the car floor vibration, the wheel/rail rolling noise transmits to carriage. An original study tries to predict low-frequency interior noise and reveal the acoustic law of panel contribution and improve ride comfort combining a wheel/rail rolling noise model, a rigid-flexible vehicletrack coupled dynamic model and detailed car body structural/acoustic finite element models. The results show that, based on the acoustic transfer vector method, the critical element contribution areas to the low-frequency noise were found; after removing the impact of critical elements, the sound pressure level peak at 80 Hz and 110-200 Hz decreased. The thickness increase can improve sound insulation level, but change the lower natural frequency, improve the structure’s stiffness, suppress the amplitude of the transfer function. Based on element contribution analysis, the damping optimization method shows that the global SPL peak decreases by 4.3, 6.4, 7.8, 1.8, 3.5, and 5.2 dB (A,) respectively, from position 1 to 6.

Long Noncoding RNA Expression Profiling During the Neuronal Differentiation of Glial Precursor Cells from Rat Dorsal Root Ganglia

Yunfei Dai,Wei Ma,Tong Zhang,Jinwei Yang,Chenghao Zang,Kuangpin Liu,Xianbin Wang,Jiawei Wang,Zhen Wu,Xingkui Zhang,Chunyan Li,Junjun Li,Xiangpeng Wang,Jianhui Guo,Liyan Li 한국생물공학회 2020 Biotechnology and Bioprocess Engineering Vol.25 No.3

Long noncoding RNAs (lncRNAs) play important roles in the process of cell fate determination. However, their function and expression profiles have not yet been systematically investigated during the transdifferentiation of glial precursor cells derived from dorsal root ganglia (DRG) in the peripheral nervous system. Our results demonstrated significant differences in gene architecture and expression among the three transcript types (lncRNA, mRNA, and TUCP). Distinct differences in transcript length, exon number, and ORF length were identified between lncRNAs and mRNAs after comparative analysis of their structure and sequence conservation. We found that the upregulated lncRNAs outnumbered the downregulated lncRNAs in glial precursor cells cultured with proBDNF antiserum compared with the levels in glial precursor cells cultured without proBDNF antiserum. By a series of GO and KEGG analyses, we found that the effects of some lncRNAs on their target genes in cis were related to nerve growth factor-induced cell cycle, cell phenotype change, and neuronal differentiation. The qRT-PCR verification results of lncRNAs ENSRNOT00000091991, ENSRNOT00000087717, and LNC_000429 were mostly consistent with the sequencing results. The candidate lncRNAs may be associated with the neuronal transdifferentiation of glial precursor cells. Our study provides the first evidence for a remarkably diverse pattern of lncRNA expression during neuronal differentiation of glial precursor cells from rat DRG, and also provides a resource for lncRNA studies in the field of cell differentiation.

Structure-borne Noise Differences of Metro Vehicle Running on Different Tracks

Yunfei Zhang,Li Li,Qian Zhu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9

A floating-slab track (FST) increases the interior noise and reduces the passenger’s acoustic comfort. A study combining experimental measurement and numerical simulation was conducted to reveal the characteristics of internal structure-borne noise on different tracks and improve riding comfort. A field measurement was taken to analyze the essential interior noise characteristics on different tracks with different speeds. A noise prediction model was built by combining a vehicle-track coupling model, the structural finite element method and the acoustic boundary element method to predict the interior noise and study the panel contribution for noise control. The results show that the sound pressure level (SPL) of FST is 5 − 10 dB higher than the ordinary monolithic track (OMT). The curve section is 1 − 4 dB larger than the straight section. In the range of 90 − 110 Hz and 135 − 150 Hz, the SPL of FST condition is higher than that of OMT condition, with a maximum difference of 12 dB. And the SPLs at five ISO positions all have peaks at 30 Hz and 90 Hz frequencies, and the sound pressure fluctuates wildly at 100 Hz. The vibration at 90 Hz is relatively violent, which leads to more significant noise, but at 110 Hz, that is small. At different frequencies, the contribution of the panels to the sound pressure in the carriage is different, and the acoustic contribution of these panels may be the opposite.

The Optimization of Genetic Algorithm in Wireless Sensor Network Coverage

Wengen Gao,Qigong Chen,Ming Jiang,Yunfei Li,Shinong Wang 보안공학연구지원센터(IJSIP) 2015 International Journal of Signal Processing, Image Vol.8 No.1

According to the maximum coverage problem in wireless sensor networks, GA algorithm combined with the standard processing method can improve the network coverage based on, but there is a risk of falling into local optimum, and costs more computation time. On the condition of analysis and proof of the effectiveness by the employment of normalization processing to resolve coding redundancy of MCSDP, further details of the evaluate conditions are proposed, and new parent selection mechanism is introduced, which both are verified by compared experiments. The experiment results show that the optimization processing method proposed in this paper retains the characteristics of existing methods, and has better optimization performance and improves the network coverage rate as well as calculation speed, which verifies the effectiveness and superiority of the method proposed in this paper.

Anti-melanogenesis effects of Ishophloroglucin A Isolated from Ishige okamurae IN α-MSH- stimulated murine melanoma cells

Yunfei Jiang,Hye-Won Yang,Xining Li,K.H.N Fernando,BoMi Ryu,You-Jin Jeon 한국수산과학회 양식분과 2019 한국수산과학회 양식분과 학술대회 Vol.2019 No.5

Assessment of Hemagglutination Activity of Porcine Deltacoronavirus

Yunfei Zhang,Li Han,Lu Xia,Yixin Yuan,Hui Hu 대한수의학회 2020 Journal of Veterinary Science Vol.21 No.1

Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus that causes diarrhea in piglets. However, the biological characteristics of PDCoV are unclear. In this study, the hemagglutination (HA) abilities of two PDCoV strains (CH-01 and HNZK-04) were investigated. Our results showed that PDCoV has the ability to agglutinate rabbit erythrocytes after virion pretreatment with trypsin or neuraminidase. Additionally, the HA assay results showed a significant positive correlation with the infectious viral titer. Our results suggest that assessing the HA activity of PDCoV may be a useful diagnostic method for investigating and surveilling PDCoV infections.

Running safety of metro train over a high-pier bridge subjected to fluctuating crosswind in mountain city

Yunfei Zhang,Jun Li,Zhaowei Chen,Xiangyang Xu 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.2

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train subjected to fluctuating crosswind. To ensure the safe operation in metro lines in mountain cities, running safety of the metro train over the high-pier bridge under crosswind is analyzed in this paper. Firstly, the dynamic model of the wind-train-bridge (WTB) system is built, in which the speed-up effect of crosswind is fully considered. On the basis of time domain analysis, the basic characteristics of the WTB system with high-pier are analyzed. Afterwards, the dynamic responses varies with train speed and wind speed are calculated, and the safety zone of metro train over a high-pier bridge subjected to fluctuating crosswind in mountain city is determined. The results indicate that, fluctuating crosswind triggers drastic vibration to the metro train and high-pier bridges, which in turn causes running instability of the train. For this reason, the corresponding safety zone for metro train running on the high-pier is proposed, and the metro traffic on the high-pier bridge should be closed as the mean wind speed of standard height reaches 9 m/s (15.6 m/s for the train).

Dynamic Contrast Enhanced Magnetic Resonance Imaging of Diffuse Spinal Bone Marrow Infiltration in Patients with Hematological Malignancies

Yunfei Zha,Maojin Li,Jianyong Yang 대한영상의학회 2010 Korean Journal of Radiology Vol.11 No.2

Objective: To investigate the significance of the dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) parameters of diffuse spinal bone marrow infiltration in patients with hematological malignancies. Materials and Methods: Dynamic gadolinium-enhanced MR imaging of the lumbar spine was performed in 26 patients with histologically proven diffuse bone marrow infiltration, including multiple myeloma (n = 6), acute lymphoblastic leukemia (n = 6), acute myeloid leukemia (n = 5), chronic myeloid leukemia (n = 7), and non-Hodgkin lymphoma (n = 2). Twenty subjects whose spinal MRI was normal, made up the control group. Peak enhancement percentage (Emax), enhancement slope (ES), and time to peak (TTP) were determined from a timeintensity curve (TIC) of lumbar vertebral bone marrow. A comparison between baseline and follow-up MR images and its histological correlation were evaluated in 10 patients. The infiltration grade of hematopoietic marrow with plasma cells was evaluated by a histological assessment of bone marrow. Results: Differences in Emax, ES, and TTP values between the control group and the patients with diffuse bone marrow infiltration were significant (t = -11.51, -9.81 and 3.91, respectively, p < 0.01). Emax, ES, and TTP values were significantly different between bone marrow infiltration groups Grade 1 and Grade 2 (Z = -2.72, -2.24 and -2.89 respectively, p < 0.05). Emax, ES and TTP values were not significantly different between bone marrow infiltration groups Grade 2 and Grade 3 (Z = -1.57, -1.82 and -1.58 respectively, p > 0.05). A positive correlation was found between Emax, ES values and the histological grade of bone marrow infiltration (r = 0.86 and 0.84 respectively, p < 0.01). A negative correlation was found between the TTP values and bone marrow infiltration histological grade (r = -0.54, p < 0.01). A decrease in the Emax and ES values was observed with increased TTP values after treatment in all of the 10 patients who responded to treatment (t = -7.92, -4.55, and 5.12, respectively, p < 0.01). Conclusion: DCE-MRI of spine can be a useful tool in detecting diffuse marrow infiltration of hematological malignancies, while its parameters including Emax, ES, and TTP can reflect the malignancies’ histological grade. Objective: To investigate the significance of the dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) parameters of diffuse spinal bone marrow infiltration in patients with hematological malignancies. Materials and Methods: Dynamic gadolinium-enhanced MR imaging of the lumbar spine was performed in 26 patients with histologically proven diffuse bone marrow infiltration, including multiple myeloma (n = 6), acute lymphoblastic leukemia (n = 6), acute myeloid leukemia (n = 5), chronic myeloid leukemia (n = 7), and non-Hodgkin lymphoma (n = 2). Twenty subjects whose spinal MRI was normal, made up the control group. Peak enhancement percentage (Emax), enhancement slope (ES), and time to peak (TTP) were determined from a timeintensity curve (TIC) of lumbar vertebral bone marrow. A comparison between baseline and follow-up MR images and its histological correlation were evaluated in 10 patients. The infiltration grade of hematopoietic marrow with plasma cells was evaluated by a histological assessment of bone marrow. Results: Differences in Emax, ES, and TTP values between the control group and the patients with diffuse bone marrow infiltration were significant (t = -11.51, -9.81 and 3.91, respectively, p < 0.01). Emax, ES, and TTP values were significantly different between bone marrow infiltration groups Grade 1 and Grade 2 (Z = -2.72, -2.24 and -2.89 respectively, p < 0.05). Emax, ES and TTP values were not significantly different between bone marrow infiltration groups Grade 2 and Grade 3 (Z = -1.57, -1.82 and -1.58 respectively, p > 0.05). A positive correlation was found between Emax, ES values and the histological grade of bone marrow infiltration (r = 0.86 and 0.84 respectively, p < 0.01). A negative correlation was found between the TTP values and bone marrow infiltration histological grade (r = -0.54, p < 0.01). A decrease in the Emax and ES values was observed with increased TTP values after treatment in all of the 10 patients who responded to treatment (t = -7.92, -4.55, and 5.12, respectively, p < 0.01). Conclusion: DCE-MRI of spine can be a useful tool in detecting diffuse marrow infiltration of hematological malignancies, while its parameters including Emax, ES, and TTP can reflect the malignancies’ histological grade.

Dynamic analysis of metro vehicle traveling on a high-pier viaduct under crosswind in Chongqing

Yunfei Zhang,Jun Li,Zhaowei Chen,Xiangyang Xu 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.5

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train under crosswind. Compared with the conditions of no-wind, crosswind triggers severer vibration of the dynamic system; compared with the short-pier viaduct, the high-pier viaduct has worse stability under crosswind. For these reasons, the running safety of the metro vehicle traveling on a high-pier viaduct under crosswind is analyzed to ensure the safe operation in metro lines in mountain cities. In this paper, a dynamic model of the metro vehicle-track-bridge system under crosswind is established, in which crosswind loads model considering the condition of wind zone are built. After that, the evaluation indices and the calculation parameters have been selected, moreover, the basic characteristics of the dynamic system with high-pier under crosswind are analyzed. On this basis, the response varies with vehicle speed and wind speed are calculated, then the corresponding safety zone is determined. The results indicate that, crosswind triggers drastic vibration to the metro vehicle and high-pier viaduct, which in turn causes running instability of the vehicle. The corresponding safety zone for metro vehicle traveling on the high-pier is proposed, and the metro traffic on the high-pier bridge under crosswind should not exceed the corresponding limited vehicle speed to ensure the running safety.