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Influence of hexapod robot foot shape on sinking considering multibody dynamics
Gang He,Zhaoyuan Cao,Qian Li,Denglin Zhu,Ji Aimin 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9
Hexapod robots have attracted attention for their excellent terrain adaptabilities. When a robot walks on soft soil, dynamic subsidence and slippage greatly reduce its walking performance. The influence of foot’s shape is usually ignored or simply studied without considering the multibody dynamics of the robot. This study is focused on the influence of the foot shape on the walking performance of a robot by coupling the sinkage with multibody dynamics. A composite contact model based on the Bekker, spring-damping, and Janosi– Hanamoto models was used to model the interaction of the robot and soft soil. Non-uniform rational B-spline (NURBS) surface and mesh were used to describe the geometries of foot and soft soil, respectively. The influences of three foot shapes on the sinkage and walking stability of the robot were analyzed by comparsion. The improved X-shaped foot reduced the robot’s sinkage and improved its walking stability.
Gang He,Yanna Zhu,Guisheng Zhang,Guotong Qiao 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.12
Security is an important problem in wireless sensor networks. Intrusion detection system is one of the most common methods of network security, for which more and more people have shown solicitude. In this paper, a dynamic random password authentication (DRPA) method is proposed for the identity authentication of communication nodes, which can detect and prevent malicious behavior at each stage of the network operation. This paper introduces the method of automatic generation of random passwords. When a user wants to communicate, the password will be verified to confirm whether it is a normal user or a malicious user. The password’s generation and verification process is very suitable for wireless sensor networks. By using NS2, the simulation experiments are carried out and the results show that this method is superior to the other methods.
Laboratory Confirmation of A Suspicious Meningococcal Meningitis Death Case
Tie-gang Zhang,Li-juan Chen,Jie Yang,Zhu-jun Shao,Xiong He,Jing-guo He,Ming Luo,Mei-ping Sun 한국미생물학회 2006 The journal of microbiology Vol.44 No.4
A suspicious meningococcal meningitis death case was reported to the Beijing CDC. The blood specimen was analyzed via multi-PCR and MLST. 6 isolates from close contacts were analyzed via PFGE and MLST. According to the results of the above analyses, the cause of this case was identified as a serogroup A Neisseria meningitidis, which, in terms of sequence typing, belonged the ST7 group.
The Molecular Characterization of Serogroup C Neisseria meningitidis Strains Circulating in Beijing
Tie-gang Zhang,Jing-guo He,Xiong He,Li-Juan Chen,Zhu-jun Shao,Mei-ping Sun 한국미생물학회 2006 The journal of microbiology Vol.44 No.6
The aim of this study was to characterize the molecular features of serogroup C Neisseria meningitidis strains circulating in Beijing, China. Twenty out of 23 strains belonged to ST 4821. The causative serosubtype for meningococcal meningitis was P1.12-1,16-8. All of the strains expressed class 3 PorB protein. Among the five pulsed-field gel electrophoresis patterns observed, pattern III predominated.
The Molecular Characterization of Serogroup C Neisseria meningitidis Strains Circulating in Beijing
Zhang, Tie-Gang,He, Jing-Guo,He, Xiong,Chen, Li-Juan,Shao, Zhu-Jun,Sun, Mei-Ping The Microbiological Society of Korea 2006 The journal of microbiology Vol.44 No.6
The aim of this study was to characterize the molecular features of serogroup C Neisseria meningitidis strains circulating in Beijing, China. Twenty out of 23 strains belonged to ST 4821. The causative serosubtype for meningococcal meningitis was P1.12-1,16-8. All of the strains expressed class 3 PorB protein. Among the five pulsed-field gel electrophoresis patterns observed, pattern III predominated.
Laboratory Confirmation of A Suspicious Meningococcal Meningitis Death Case
Zhang Tie-Gang,He Xiong,Chen Li-Juan,He Jing-Guo,Luo Ming,Yang Jie,Shao Zhu-Jun,Sun Mei-Ping The Microbiological Society of Korea 2006 The journal of microbiology Vol.44 No.4
A suspicious meningococcal meningitis death case was reported to the Beijing CDC. The blood specimen was analyzed via multi-PCR and MLST. 6 isolates from close contacts were analyzed via PFGE and MLST. According to the results of the above analyses, the cause of this case was identified as a serogroup A Neisseria meningitidis, which, in terms of sequence typing, belonged the ST7 group.
A numerical method for evaluating fire performance of prestressed concrete T bridge girders
Gang Zhang,Venkatesh Kodur,Chaojie Song,Wei Hou,Shuanhai He 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.6
This paper presents a numerical method for evaluating fire performance of prestressed concrete (PC) T shaped bridge girders under combined effect of structural loading and hydrocarbon fire exposure conditions. A numerical model, developed using the computer program ANSYS, is employed to investigate fire response of PC T shaped bridge girders by taking into consideration structural inherent parameters, namely; arrangement of prestressing strands with in the girder section, thickness of concrete cover over prestressing strands, effective degree of prestress and content of prestressing strands. Then, a sequential thermo-mechanical analysis is performed to predict cross sectional temperature followed by mechanical response of T shaped bridge girders. The validity of the numerical model is established by comparing temperatures, deflections and failure time generated from fire tests. Through numerical studies, it is shown that thickness of concrete cover and arrangement of prestressing strands in girder section have significant influence on the fire resistance of PC T shaped bridge girders. Increase in effective degree of prestress in strands with triangular shaped layout and content in prestressing strands can slow down the progression of deflections in PC T shaped bridge girder towards the final stages of fire exposure, to thereby preventing sudden collapse of the girder. Rate of deflection based failure criterion governs failure in PC T shaped bridge girders under most hydrocarbon fire exposure conditions. Structural inherent parameters incorporated into sectional configuration can significantly enhance fire resistance of PC bridge girders; thus mitigating fire induced collapse of these bridge girders.
Thermo-mechanical behavior of prestressed concrete box girder at hydration age
Gang Zhang,Meichun Zhu,Shuanhai He,Wei Hou 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.5
Excessively elevated temperature can lead to cracks in prestressed concrete (PC) continuous bridge with box girder on the pier top at cement hydration age. This paper presents a case study for evaluating the behavior of PC box girder during the early hydration age using a two-stage computational model, in the form of computer program ANSYS, namely, 3-D temperature evaluation and determination of mechanical response in PC box girders. A numerical model considering time-dependent wind speed and ambient temperature in ANSYS for tracing the thermal and mechanical response of box girder is developed. The predicted results were compared to show good agreement with the measured data from the PC box girder of the Zhaoshi Bridge in China. Then, based on the validated numerical model three parameters were incorporated to analyze the evolution of the temperature and stress within box girder caused by cement hydration heat. The results of case study indicate that the wind speed can change the degradation history of temperature and stress and reduce peak value of them. The initial casting temperature of concrete is the most significant parameter which controls cracking of PC box girder on pier top at cement hydration age. Increasing the curing temperature is detrimental to prevent cracking.
He, Shan-Yang,Xu, Lin,Niu, Gang,Ke, Pei-Qi,Feng, Miao-Miao,Shen, Hong-Wei Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.5
Objective: We aimed to analyze the association between excision repair cross-complementing rodent repair deficiency complementation group 1 (XRCC1) and ovarian cancer risk. Methods: We performed a hospital-based case-control study with 155 cases and 313 controls in China. All Chinese cases with newly diagnosed primary ovarian cancer between May 2005 to May 2010 in our hospital were invited to participate within 2 months of diagnosis. Controls were randomly selected from people who requested general health examinations in the same hospital during the same period. SNPs in EXCC1, ERCC1 C8092A and ERCC1 T19007C, were analyzed by PCR-RFLP method. Results: We observed a non-significantly increased risk of ovarian cancer among individuals with ERCC1 8092TT compared with those with the 8092CC genotype (adjusted OR=1.55, 95% CI%=0.74-2.97). Moreover, 19007TT genotype carriers also showed a non-significant increased risk of ovarian cancer over those with the 19007CC genotype (adjusted OR=1.78, 95% CI%=0.91-3.64). Conclusion: Our firstly investigation of links between polymorphisms in the ERCC1 gene and the risk of ovarian cancer in Chinese population demonstrated no significant association. Further large sample studies in Chinese populations are needed.