Dynamic characteristics of a planetary gear system based on contact status of the tooth surface

Ruibo Chen,Jianxing Zhou,Wenlei Sun 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

Studies on the planetary gear have attracted considerable attention because of its advantages, such as compactness, large torque-toweight ratio, vibrations, and high efficiency, which have resulted in its wide applications in industry, wind turbine, national defense, and aerospace fields. We have established a novel dynamic model of the planetary gear transmission by using Newton’s theory, in which some key factors such as time-variant meshing stiffness, phase relationships, and tooth contact characteristics are considered. The influences of gear axial tipping, operating conditions, and the meshing phase on the contact characteristics and the dynamic characteristics were researched systematically. It was found that the contact area of the tooth surface was moved due to the axial gear tipping, which obviously affected the meshing stiffness. With the increase in the inclination angle of the sun gear, the meshing stiffness decreases, which produces an evident influence on the high natural frequency in the planetary transmission system. In terms of the dynamic characteristics of the system, the component of rotating frequency appeared in the dynamic meshing force of the sun gear and the planetary gear. Moreover, the floating track of the center wheel varied significantly and exhibited an oval distribution as the inclination angle of the sun gear changed. When the inclination angle of the sun gear increased, the rotating frequency component increased significantly, but the other meshing frequency components remained unchanged; meanwhile, the deformation of the floating track also increased. If the inclination angle of the sun gear changes, the vibration state of the system and the collision impact could become more serious, and the lifetime of the planetary transmission system will reduce. Furthermore, when the load was increased, we found that the gear-tooth contact zone transformed from line contact to surface contact, the meshing stiffness increased, the effect of high natural frequency on the planetary transmission system became more evident, but its low-order natural frequency remained stable. With regard to the dynamic characteristics of the system, the components of the major frequency at the external gearing remained unchanged, but the rotation frequency of the sun gear and the meshing frequency amplitude increased linearly with the increase in load. In conclusion, the variation in the meshing stiffness of the planetary gear system had minor impact on the low-order natural frequency, but had a significant impact on the high natural frequency of the planetary transmission system due to the phase variation of the gear.

A novel ceramic GEM used for neutron detection

Zhou, Jianrong,Zhou, Xiaojuan,Zhou, Jianjin,Jiang, Xingfen,Yang, Jianqing,Zhu, Lin,Yang, Wenqin,Yang, Tao,Xu, Hong,Xia, Yuanguang,Yang, Gui-an,Xie, Yuguang,Huang, Chaoqiang,Hu, Bitao,Sun, Zhijia,Chen, Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6

A novel ceramic Gas Electron Multiplier (GEM) has been developed to meet the demand of high counting rate for the neutron detection which is an alternative to ³He-based detector at China Spallation Neutron Source (CSNS). An experiment was performed to measure the neutron transmittance of ceramic-GEM and FR4-GEM at the small angle neutron scattering (SANS) instrument. The result showed the ceramic-GEM has higher transmittance and less self-scattering especially for cold neutrons. One single ceramic GEM could give a gain of 10²-10⁴ in the mixture gas of Ar and CO₂ (90%:10%) and its energy resolution was about 27.7% by using ⁵⁵Fe X ray of 5.9 keV. A prototype has been developed in order to investigate the performances of the ceramic GEM-based neutron detector. Several neutron beam tests, including detection efficiency, spatial resolution, two-dimensional imaging, and wavelength spectrum, were carried out at CSNS and China Mianyang Research Reactor (CMRR). The results show that the ceramic GEM-based neutron detector is a good candidate to measure the high intensity neutrons.

Long Term Outcomes and Prognostic Factors of N₀ Stage Nasopharyngeal Carcinoma: a Single Institutional Experience with 610 Patients

Sun, Jian-Da,Chen, Chuang-Zhen,Chen, Jian-Zhou,Li, Dong-Sheng,Chen, Zhi-Jian,Zhou, Ming-Zhen,Li, De-Rui Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.5

Treatment responses of $N_0$ stage nasopharyngeal carcinoma were firstly analyzed comprehensively to evaluate long term outcomes of patients and identify prognostic factors. A total of 610 patients with $N_0$ NPC, undergoing definitive radiotherapy to their primary lesion and prophylactic radiation to upper neck, were reviewed retrospectively. Concomitant chemotherapy was administrated to 65 out of the 610. Survival rates of the patients were calculated using the Kaplan-Meier method and compared by log-rank test. Prognostic factors were identified by the Cox regression model. The study revealed the 5-year and 10-year overall, disease-free, disease-specific, local failure-free, regional failure-free, locoregional failure-free and distant metastasis-free survival rates to be 78.7% and 66.8%, 68.8% and 55.8%, 79.9% and 70.4%, 81.2% and 72.5%, 95.8% and 91.8%, 78.3% and 68.5%, 88.5% and 85.5%, respectively. There were 192 patients experiencing failure (31.5%) after radiotherapy or chemoradiotherapy. Of these, local recurrence, regional relapse and distant metastases as the first event of failure occurred in 100 (100/610, 16.4%), 15(15/610, 2.5%) and 52 (52/610, 8.5%), respectively. Multivariate analysis showed that T stage was the only independent prognostic factor for patients with $N_0$ NPC (P=0.000). Late T stage (P=0.000), male (P=0.039) and anemia (P=0.007) were independently unfavorable factors predicting disease-free survival. After treatment, satisfactory outcome wasgenerally achieved in patients with $N_0$ NPC. Local recurrence represented the predominant mode of treatment failure, while T stage was the only independent prognostic factor for overall survival. Late T stage, male gender, and anemia independently predicted lower possibility of the disease-free survival.

Benzidine Induces Epithelial-Mesenchymal Transition of Human Bladder Cancer Cells through Activation of ERK5 Pathway

Sun, Xin,Zhang, Tao,Deng, Qifei,Zhou, Qirui,Sun, Xianchao,Li, Enlai,Yu, Dexin,Zhong, Caiyun Korean Society for Molecular and Cellular Biology 2018 Molecules and cells Vol.41 No.3

Benzidine, a known carcinogen, is closely associated with the development of bladder cancer (BC). Epithelial-mesenchymal transition (EMT) is a critical pathophysiological process in BC progression. The underlying molecular mechanisms of mitogen-activated protein kinase (MAPK) pathway, especially extracellular regulated protein kinases 5 (ERK5), in regulating benzidine-induced EMT remains unclarified. Hence, two human bladder cell lines, T24 and EJ, were utilized in our study. Briefly, cell migration was assessed by wound healing assay, and cell invasion was determined by Transwell assay. Quantitative PCR and western blot were utilized to determine both gene expressions as well as protein levels of EMT and MAPK, respectively. Small interfering RNA (siRNA) was transfected to further determine ERK5 function. As a result, the migration and invasion abilities were enhanced, epithelial marker expression was decreased while mesenchymal marker expression was increased in human BC cell lines. Meanwhile, benzidine administration led to activation of ERK5 and activator protein 1 (AP-1) proteins, without effective stimulation of the Jun N-terminal kinase (JNK) or p38 pathways. Moreover, Benzidine-induced EMT and ERK5 activation were completely suppressed by XMD8-92 and siRNAs specific to ERK5. Of note, ERK1/2 was activated in benzidine-treated T24 cells, while benzidine-induced EMT could not be reversed by U0126, an ERK1/2 inhibitor, as indicated by further study. Collectively, our findings revealed that ERK5-mediated EMT was critically involved in benzidine-correlated BC progression, indicating the therapeutic significance of ERK5 in benzidine-related BC.

BINDING NUMBERS AND FRACTIONAL (g, f, n)-CRITICAL GRAPHS

ZHOU, SIZHONG,SUN, ZHIREN The Korean Society for Computational and Applied M 2016 Journal of applied mathematics & informatics Vol.34 No.5

Let G be a graph, and let g, f be two nonnegative integer-valued functions defined on V (G) with g(x) ≤ f(x) for each x ∈ V (G). A graph G is called a fractional (g, f, n)-critical graph if after deleting any n vertices of G the remaining graph of G admits a fractional (g, f)-factor. In this paper, we obtain a binding number condition for a graph to be a fractional (g, f, n)-critical graph, which is an extension of Zhou and Shen's previous result (S. Zhou, Q. Shen, On fractional (f, n)-critical graphs, Inform. Process. Lett. 109(2009)811-815). Furthermore, it is shown that the lower bound on the binding number condition is sharp.

Expression of Neurotrophin 4 and Its Receptor Tyrosine Kinase B in Reproductive Tissues during the Follicular and Luteal Phases in Cows

Sun, Yongfeng,Li, Chunjin,Sun, Yanling,Chen, Lu,Liu, Zhuo,Ma, Yonghe,Wang, Chunqiang,Zhang, Wei,Zhou, Xu Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.3

The neurotrophins, required for the survival and differentiation of the nervous system, are known to be important for the development of the reproductive tissues. However, the signals initiating the growth of follicles, gamete development, and transport and the development of zygote in the reproductive system of cows remain ambiguous. The purpose of the present study was to identify the transcripts and proteins of Neurotrophin 4 (NT4) and its receptor tyrosine kinase B (TrkB) in bovine reproductive tissues. The transcripts and immunoreactivity of NT4 and TrkB proteins were detected by reverse transcription polymerase chain reaction and western blot analysis. Using immunohistochemistry, the specific immunoreactivity of NT4 and TrkB were detected in the oocytes of primordial follicles and in the growing primary follicles. The NT4 and TrkB immunoreactivity was predominantly observed in granulosa cells, cumulus granulosa cells, cumulus oocyte complexes, theca cells of mature follicles, as well as in the oviduct epithelial cells, uterine gland cell, and epithelium cells of the uterus during the follicular and luteal phases in cows. Expressions of NT4 and TrkB mRNAs were not significantly different among the ovary, oviduct, and uterus of the follicular phase. For the luteal phase, the expression of NT4 mRNA in the ovary was significantly higher than that in the oviduct and uterus, and the expression of TrkB mRNA in the oviduct was significantly higher than that in the ovary and uterus, as determined by fluorescence quantitative reverse transcription polymerase chain reaction. The expression of NT4 mRNA was significantly higher than that of TrkB mRNA in the ovary and uterus, whereas NT4 mRNA expression was lower than that of TrkB mRNA in the oviduct during the luteal phase. The present study hypothesizes that NT4 participates in the regulation of both gonads and extra-gonadal reproductive tissues in cows.

A Study on Status Quo and Problems of Cultural Exchange of Bangladesh-China-India-Myanmar Economic Corridor from the Perspective of Soft Power

Sun Xiqin,He Hongmei,Zhou Yunsong,Zhou Yuting 한국정치사회연구소 2019 한국과 국제사회 Vol.3 No.2

소프트 파워는 국제 교류 및 지역 협력에서 중요한 역할을 하고 있다. 방글라데시·중국·인도·미얀마 지역은 지리적으로 보면 서로 인접되어 있으며 역사적으로 왕래가 빈번한다. 2013년 중·인 양국이 방글라데시·중국·인도·미얀마 경제회랑 건설을 제의한 후에, 방글라데시와 미얀마가 이 제안에 적극적으로 호응하면서 4국 간의 교류는 더욱 밀접해진다. 방·중·인·미 경제회랑 지역은 중국 서남과 방글라데시·인도·미얀마를 연결하는 중요한 통로 될 것이고, 이를 통해 관련지역의 문화교류도 많아질 것이다. 하지만 4국 간에는 문화교류는 중국과 인도의 소프트 파워에 의해 불균형한 상태로 보인다. 중국·인도는 방글라데시·미얀마에 대해 문화 제품이 더 많이 수출하고 있고, 이는 많은 분야에서 방글라데시와 미얀마에게 영향을 주고 있다. 향후에 이 경제회랑은 문화교류 및 협력 가속화하는 배경 하에, 지속 가능한 발전 체제를 구축해 나가야하며, 이를 통해 4국의 소프트 파워 영향력을 균형화시켜서 지역문화의 백화제방(百花齐放)를 달성할 것이다. Nowadays, soft power is playing a more important role in international communication and cooperation, and as cultural exchange in regional cooperation is deeply influenced by national soft powers, the development is usually unbalanced. Bangladesh, China, India and Myanmar are adjacent to each other with a long history of intercourse. In the year 2013, initiation of constructing Bangladesh-China-India-Myanmar Economic Corridor advocated by China and India was responded positively by Bangladesh and Myanmar. Since then, the world has witnessed an increasing connection of these four countries. Being the critical bond connecting the southwestern areas of China and Bangladesh, India as well as Myanmar, Bangladesh-China-India-Myanmar Economic Corridor is characterized by multiple regional cultures along with frequent connections in cultural products and activities. However, cultural exchange now is dominated by imbalanced development due to potent soft power of China and India that these two countries export more cultural products to the rest, which has an impact in many fields of Bangladesh and Myanmar. Priority should be given to coordinated development in cultural exchange regarding the construction of Bangladesh-China-India-Myanmar Economic Corridor. Only by developing a sustainable development mechanism for cultural exchange, to coordinate the influences of soft powers of these four countries, then a fine complexion of all flowers are in bloom can be created, returning to five original intention of the construction of this economic corridor: “Policy Communication” and “Strength People-to-people Ties”, etc.

Study on the Patterns of Library Resource Construction and Services in MOOC

Sun Ji-Zhou,Liao Sheng-Feng 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.5

It is of great significance to reform the patterns of library resource construction and services in MOOC, for example, it can help to fulfill the individual needs of learners, and achieve sustainable development for the library. Firstly, the author analyzes the characteristics of MOOC; secondly, discusses the characteristics of information construction of library; and then designs a knowledge discovery model of the library information resources construction in MOOC; finally proves that it could provide favorable support for the improvement of library resource construction and services to discover knowledge from library data base according to the result of case study.

Study on the Patterns of Library Resource Construction and Services in MOOC

Sun Ji-zhou,Liao Sheng-feng 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.6

It is of great significance to reform the patterns of library resource construction and services in MOOC, for example, it can help to fulfill the individual needs of learners, and achieve sustainable development for the library. Firstly, the author analyzes the characteristics of MOOC; secondly, discusses the characteristics of information construction of library; and then designs a knowledge discovery model of the library information resources construction in MOOC; finally proves that it could provide favorable support for the improvement of library resource construction and services to discover knowledge from library data base according to the result of case study.

Full-scale test of dampers for stay cable vibration mitigation and improvement measures

Zhou, Haijun,Xiang, Ning,Huang, Xigui,Sun, Limin,Xing, Feng,Zhou, Rui Techno-Press 2018 Structural monitoring and maintenance Vol.5 No.4

This paper reported test of full-scale cables attached with four types of dampers: viscous damper, passive Magneto-Rheological (MR) damper, friction damper and High Damping Rubber (HDR) damper. The logarithmic decrements of the cable with attached dampers were calculated from free vibration time history. The efficiency ratios of the mean damping ratios of the tested four dampers to theoretical maximum damping ratio were derived, which was very important for practical damper design and parameter optimization. Non-ideal factors affecting damper performance were discussed based on the test results. The effects of concentrated mass and negative stiffness were discussed in detail and compared theoretically. Approximate formulations were derived and verified using numerical solutions. The critical values for non-dimensional concentrated mass coefficient and negative stiffness were identified. Efficiency ratios were approximately 0.6, 0.6, and 0.3 for the viscous damper, passive MR damper and HDR damper, respectively. The efficiency ratio for the friction damper was between 0-1.0. The effects of concentrated mass and negative stiffness on cable damping were positive as both could increase damping ratio; the concentrated mass was more effective than negative stiffness for higher vibration modes.