Research on Natural Gas Leakage Diffusion of Urban Underground Pipeline and its Explosion Hazard

Dai Wang,Peng Liu,Chenguang Hua,Hai Zhang,Chenyang Shi,Jianmei Du 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

For the risk of gas leakage and explosion that may occur during the serviceability of urban natural gas pipeline, based on the numerical simulation conducted by FLACS, the gas leakage, explosion and disaster risk under the different speed of wind are mainly studied with local climate characteristics for actual urban street. The results show that the wind speed has an obvious effect on the gas leakage and diffusion, the deviation of gas leakage direction is not obvious for the smaller speed of wind at the initial stage, the horizontal diffusion range gradually increases with the increase of wind speed, while the vertical diffusion range gradually decreases, and the volume of gas at the limit concentration of combustion and explosion gradually decreases. In urban buildings, the overpressure load of higher buildings is lower. After the explosion, the peak overpressure at the same monitoring point decreases with the increase of wind speed. With the increase of distance from the building to the explosion location, the overpressure load on the building decreases and the oscillation effect of overpressure load is relatively gentle. The thermal radiation after burning has great influence on the surrounding buildings and downwind position, especially the buildings around the leakage point.

Multi-objective intelligent cooperative design for interference fit of the conical sleeve

Ke Ning,Jianmei Wang,Pu Li,Dan Xiang,Dingbang Hou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

This paper deals with the multi-objective intelligent cooperative optimization for interference fit of conical sleeve. The influence of various factors on contact pressure of conical sleeve was quantitatively analyzed, and the relationship among multi-objectives and multivariables was comprehensively built. Take the cone sleeve of oil film bearing as the research object, the key factors of the cone sleeve were determined with a combination of actual situations, and its sample data was obtained by central composite test design. Considering the multi-objective involving yield strength, torque and mass, the approximate model of the response surface based on the kriging algorithm was given. Then, a multi-objective intelligent cooperative design method for interference fit of the cone sleeve was established by solving the NSGA-II algorithm. Example analysis has shown that such a method makes up for the deficiency of theoretical design to ignore the stress concentration problem, and its accuracy is 32 times that of the BP neural network algorithm. Finally, the experiments verified the correctness of this method.

Attenuation of Aortic Injury by Ursolic Acid through RAGE-Nox-NFκB Pathway in Streptozocin-induced Diabetic Rats

Min Xiang,Jianmei Wang,Yaqin Zhang,Jing Ling,Xiaoyue Xu 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.5

Vascular complications are the leading causes of morbidity and mortality in diabetes mellitus (DM). The RAGE (receptor for advanced glycation end products)-NADPH oxidase-NF-κB signal transduction pathway plays an important role in the development of oxidative stressrelated vascular complications in DM. Ursolic acid (UA), a pentacyclic triterpenoid derived from plants, has been reported to have multiple pharmacological effects, including a potent antioxidant activity. This study aimed to investigate both the effect of UA on aortic injury in streptozotocin (STZ)-induced diabetic rats and the drug’s mechanism of action. STZ-induced diabetic animals were randomized in one of the following 4 groups: no treatment (diabetic model group), aminoguanidine (AG, 100 mg/kg), high-dose UA (50 mg/kg), and low-dose UA (25 mg/kg). A non-diabetic control group was followed concurrently. After 8 weeks, the diabetic model rats exhibited: severe aortic arch injury, histologically elevated serum glucose, fructosamine, and glycosylated hemoglobin; and accumulation of advanced glycation end products (AGEs) in the arota. In addition, the levels of RAGE protein, transcription factor NF-κB p65, and the p22phox subunit of NADPH oxidase were increased, as were the serum levels of malondialdehyde and tumor necrosis factor-alpha (TNF-α; p < 0.01 vs control), suggesting that the mechanisms of oxidative stress contributed to vascular injury in the diabetic model group. In contrast, rats treated with UA (50 mg/kg) had a markedly less vascular injury and significantly improved biochemical parameters. Oxidative balance was also normalized in the UAtreated rats, and a marked reduction in the levels of RAGE and p22phox paralleled the reduced activation of NF-κB p65 and TNF-α (p < 0.01 and p < 0.05, respectively, vs diabetic model). These findings suggest that UA may suppress oxidative stress, thus blunting activation of the RAGE-NADPH oxidase-NF-κB signal transduction pathway, to ameliorate vascular injury in the STZ-induced DM rats.

External Magnetic Field of Journal Bearing with Twined Solenoid

Yanjuan Zhang,Jianmei Wang,Decai Li 한국자기학회 2017 Journal of Magnetics Vol.22 No.2

In this paper, the distribution of internal magnetic induction intensity of oil-film bearing twined solenoids was proposed. The magnetic field was generated by solenoids and magnetized bearing. The magnetized bearing was simplified as solenoid model. The mathematical model of magnetic induction intensity at any point of finite solenoid was deduced. Through experiment method, the distribution of the internal magnetic induction intensity of oil-film bearing and the magnetizing current formula of bearing was obtained. Further, the magnetic induction intensity distribution of magnetization bearing was solved successfully. The results showed that the magnetic induction was a second-degree parabola with open upwards along the axial plane and the distribution of magnetic induction intensity was opposite to the rule of magnetic induction intensity generated by solenoids. In addition, the magnetic flux density increased linearly with the increase of current.

Alkyl-substituted carbazole/pyridine hybrid host materials for efficient solution-processable blue- and green-emitting phosphorescent OLEDs

Chao Tang,Jianmei Chen,Yuxin Li,Xinchao Liu,Lili Zhang,Fangfang Wang,Jia Hu,Xudong Cao,Tao Jiang 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.2

Three new pyridine-cored alkyl-substituted carbazole derivatives of 2,6-bis(2,7-dimethyl-9H-carbazol-9-yl)pyridine(2,7-MeCzPy), 2,6-bis(3,6-dimethyl-9H-carbazol-9-yl) pyridine (3,6-MeCzPy) and 2,6-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)pyridine (3,6-tBuCzPy) were synthesized by means of connecting methyl or tert-butyl substituents on the3,6 or 2,7 positions of carbazole with pyridine ring as the core. The influence of different alkyl and linkages modeon the thermal, photophysical, electrochemical properties and devices electrolumiescent (EL) performances of thecompounds were comprehensively studied. In solution-processed blue or green phosphorescent organic light-emittingdiodes (PHOLEDs) with bis[2-(4,6-difluorophenyl)-pyridinato-N,C2] picolinate iridium(III) (FIrpic) or fac-tris(2-phenylpyridine)iridium (Ir(ppy)3) as phosphorescent dopants, EL performances follow the same sequence of 2,7-MeCzPy> 3,6-tBuCzPy > 3,6-MeCzPy, the trend is consistent with the value of triplet energies (ET). Devices hosted by2,7-MeCzPy achieving the best EL performance, exhibited maxima 13.6 cd A−1 and 7.0 lm W−1 for current efficiency(CE) and power efficiency (PE) in blue PHOLEDs, maxima 26.2 cd A−1 and 16.2 lm W−1 for CE and PE in greenPHOLEDs.

Investigation of flexural strength and porosity of porous Si₃N₄ ceramics through orthogonal experimental design

Juanli Yu,Jianmei Hou,Jian Zhang,Guanjun Qiao,Zhihao Jin,Hongjie Wang 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

Porous Si3N4 ceramics by a gel casting preparation route have received considerable attention because of their excellent performance. In this paper, orthogonal experimental design L16(45) was used to investigate the preparation of porous Si3N4 ceramics by a gelcasting technique. Three variables including solid loading, monomer content and the ratio of monomers were studied. Through range analysis and variance analysis, the results suggest that the ratio of monomers has a significant influence on both the flexural strength and porosity of Si3N4 sintered bodies. For the flexural strength of a Si3N4 sintered body, the order of significance levels was as follows: the ratio of monomers, solid loading and monomer content. For the porosity of a Si3N4 sintered body, the order of significance levels was as follows: the ratio of monomers, monomer content and solid loading. The experimental results suggest also that solid loading has an optimum value where the flexural strength can achieve a maximum value. Porous Si3N4 ceramics by a gel casting preparation route have received considerable attention because of their excellent performance. In this paper, orthogonal experimental design L16(45) was used to investigate the preparation of porous Si3N4 ceramics by a gelcasting technique. Three variables including solid loading, monomer content and the ratio of monomers were studied. Through range analysis and variance analysis, the results suggest that the ratio of monomers has a significant influence on both the flexural strength and porosity of Si3N4 sintered bodies. For the flexural strength of a Si3N4 sintered body, the order of significance levels was as follows: the ratio of monomers, solid loading and monomer content. For the porosity of a Si3N4 sintered body, the order of significance levels was as follows: the ratio of monomers, monomer content and solid loading. The experimental results suggest also that solid loading has an optimum value where the flexural strength can achieve a maximum value.

Hybrid prediction method of load-carrying capacity considering boundary condition of expansion joint sleeve and rotation angle of spindle

Yongqiang Guan,Jianmei Wang,Ke Ning,Dingbang Hou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

Taking the double-cone expansion joint sleeve (EJS) as an example, this paper proposes a hybrid prediction method of load-carrying capacity considering the displacement boundary conditions of EJS and rotation angle of spindle, and a comprehensive optimization method for the structure of EJS is established using this method. Firstly, based on the thickwalled cylinder theory and considering the displacement boundary conditions of interference contact surface, a new calculation method for calculating torque is presented, and the main parameters affecting load-carrying capacity are determined. Secondly, the finite element method is used to simulate assembly process and working process of EJS to obtain the ultimate torque, the effects of inner ring, outer ring, taper, elastic modulus, and friction coefficient are investigated. Based on the hybrid prediction results of load-carrying capacity, the multi-objective optimization is carried out using genetic algorithm through the construction of orthogonal experimental combination, the optimization of structural parameters of EJS is realized. The results indicate that the maximum equivalent stress is reduced by 20.88 %, the ultimate torque is increased by 0.23 %, and the mass is reduced by 5.11 %. It is proved that the method can effectively reduce maximum equivalent stress and solve design defects caused by stress concentration.

Load-Carrying Capacity Prediction of Magnetic Fluid Hydrodynamic Bearing Under External Magnetic Field

Yaqi Zhao,Jianmei Wang,Dingbang Hou,Jinsheng Hou 한국자기학회 2021 Journal of Magnetics Vol.26 No.1

Identification of genes involved in inbreeding depression of reproduction in Langshan chickens

Xue Qian,Li Guohui,Cao Yuxia,Yin Jianmei,Zhu Yunfen,Zhang Huiyong,Zhou Chenghao,Shen Haiyu,Dou Xinhong,Su Yijun,Wang Kehua,Zou Jianmin,Han Wei 아세아·태평양축산학회 2021 Animal Bioscience Vol.34 No.6

Objective: Inbreeding depression of reproduction is a major concern in the conservation of native chicken genetic resources. Here, based on the successful development of strongly inbred (Sinb) and weakly inbred (Winb) Langshan chickens, we aimed to evaluate inbreeding effects on reproductive traits and identify candidate genes involved in inbreeding depression of reproduction in Langshan chickens. Methods: A two-sample t-test was performed to estimate the differences in phenotypic values of reproductive traits between Sinb and Winb chicken groups. Three healthy chickens with reproductive trait values around the group mean values were selected from each of the groups. Differences in ovarian and hypothalamus transcriptomes between the two groups of chickens were analyzed by RNA sequencing (RNA-Seq). Results: The Sinb chicken group showed an obvious inbreeding depression in reproduction, especially for traits of age at the first egg and egg number at 300 days (p<0.01). Furthermore, 68 and 618 differentially expressed genes (DEGs) were obtained in the hypothalamus and ovary between the two chicken groups, respectively. In the hypothalamus, DEGs were mainly enriched in the pathways related to vitamin metabolism, signal transduction and development of the reproductive system, such as the riboflavin metabolism, Wnt signaling pathway, extracellular matrix-receptor interaction and focal adhesion pathways, including stimulated by retinoic acid 6, serpin family F member 1, secreted frizzled related protein 2, Wnt family member 6, and frizzled class receptor 4 genes. In the ovary, DEGs were significantly enriched in pathways associated with basic metabolism, including amino acid metabolism, oxidative phosphorylation, and glycosaminoglycan degradation. A series of key DEGs involved in folate biosynthesis (gamma-glutamyl hydrolase, guanosine triphosphate cyclohydrolase 1), oocyte meiosis and ovarian function (cytoplasmic polyadenylation element binding protein 1, structural maintenance of chromosomes 1B, and speedy/RINGO cell cycle regulator family member A), spermatogenesis and male fertility (prostaglandin D2 synthase 21 kDa), Mov10 RISC complex RNA helicase like 1, and deuterosome assembly protein 1) were identified, and these may play important roles in inbreeding depression in reproduction. Conclusion: The results improve our understanding of the regulatory mechanisms underlying inbreeding depression in chicken reproduction and provide a theoretical basis for the conservation of species resources. Objective: Inbreeding depression of reproduction is a major concern in the conservation of native chicken genetic resources. Here, based on the successful development of strongly inbred (Sinb) and weakly inbred (Winb) Langshan chickens, we aimed to evaluate inbreeding effects on reproductive traits and identify candidate genes involved in inbreeding depression of reproduction in Langshan chickens.Methods: A two-sample t-test was performed to estimate the differences in phenotypic values of reproductive traits between Sinb and Winb chicken groups. Three healthy chickens with reproductive trait values around the group mean values were selected from each of the groups. Differences in ovarian and hypothalamus transcriptomes between the two groups of chickens were analyzed by RNA sequencing (RNA-Seq).Results: The Sinb chicken group showed an obvious inbreeding depression in reproduction, especially for traits of age at the first egg and egg number at 300 days (p<0.01). Furthermore, 68 and 618 differentially expressed genes (DEGs) were obtained in the hypothalamus and ovary between the two chicken groups, respectively. In the hypothalamus, DEGs were mainly enriched in the pathways related to vitamin metabolism, signal transduction and development of the reproductive system, such as the riboflavin metabolism, Wnt signaling pathway, extracellular matrix-receptor interaction and focal adhesion pathways, including stimulated by retinoic acid 6, serpin family F member 1, secreted frizzled related protein 2, Wnt family member 6, and frizzled class receptor 4 genes. In the ovary, DEGs were significantly enriched in pathways associated with basic metabolism, including amino acid metabolism, oxidative phosphorylation, and glycosaminoglycan degradation. A series of key DEGs involved in folate biosynthesis (gamma-glutamyl hydrolase, guanosine triphosphate cyclohydrolase 1), oocyte meiosis and ovarian function (cytoplasmic polyadenylation element binding protein 1, structural maintenance of chromosomes 1B, and speedy/RINGO cell cycle regulator family member A), spermatogenesis and male fertility (prostaglandin D2 synthase 21 kDa), Mov10 RISC complex RNA helicase like 1, and deuterosome assembly protein 1) were identified, and these may play important roles in inbreeding depression in reproduction.Conclusion: The results improve our understanding of the regulatory mechanisms underlying inbreeding depression in chicken reproduction and provide a theoretical basis for the conservation of species resources.