Fabrication and properties of machinable SiC/h-BN Nano-composites

Hai-yun Jin,Nai-kui Gao,Zong-ren Peng,Guan-jun Qiao,Ji-qiang Gao 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

SiC/BN ceramic nano-composites powders were synthesized by an in-situ recation method and the composites were sintered by hot pressing in a N2 atmosphere. The microstructure, secondary phase and grain boundaries were characterized using a range of analytical techniques including TEM, SEM and XRD. The mechanical properties were determined, when the BN content is increaed because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites decreased more slowly than that of the SiC/h-BN micro-composites, but the hardness of the composites decreased sharply and the machinability properites were improved noticeably. SiC/BN ceramic nano-composites powders were synthesized by an in-situ recation method and the composites were sintered by hot pressing in a N2 atmosphere. The microstructure, secondary phase and grain boundaries were characterized using a range of analytical techniques including TEM, SEM and XRD. The mechanical properties were determined, when the BN content is increaed because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites decreased more slowly than that of the SiC/h-BN micro-composites, but the hardness of the composites decreased sharply and the machinability properites were improved noticeably.

Event-triggered Pinning Bipartite Tracking Consensus of the Multi-agent System Subject to Input Saturation

Hai-Yun Gao,Ai-Hua Hu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.9

This paper focuses on the bipartite tracking consensus problem of the multi-agent system with cooperative-competitive interactions. In order to save resources, an event-triggered pinning scheme subjected to input saturation is designed. Suppose that the signed graph representing cooperative-competitive interactions is structurally balanced, and the initial states for the agents belong to the specified ellipsoid. By using Lyapunov theory and linear matrix inequality (LMI) techniques, some sufficient conditions are derived to ensure that the bipartite tracking consensus of the system under event-triggered pinning control can be achieved. Moreover, the bipartite tracking consensus of system with Lipschitz nonlinear dynamics is also investigated, and Zeno behavior can be excluded. Subsequently, numerical examples are provided to illustrate the effectiveness of the obtained results.

Corrosion behavior and creepage discharze character for machinable AlN/h-BN ceramic composites

Hai-yun Jin,Bo He,Nai-kui Gao,Zong-ren Peng,Ji-qiang Gao 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5

AlN particles coated with nano-BN were synthesized. The AlN/BN ceramic composites were sintered by Plasma Active Sintering (PAS). Because the nano-BN crystals were homogeneously dispersed around the AlN grains of the matrix, the chemical corrosion resistance of AlN/nano-sized h-BN ceramic composites was higher than that of AlN/micro-sized h-BN ceramic composites and monolithic AlN ceramics. Due to the better hydrophobic property of h-BN, the AlN/BN composites had a better hydrophobic property than the monolithic AlN ceramic, at the same time, because of the homogeneous dispersion of the nano-BN, the creepage discharze voltage of AlN/nano-sized BN composites was the highest. AlN particles coated with nano-BN were synthesized. The AlN/BN ceramic composites were sintered by Plasma Active Sintering (PAS). Because the nano-BN crystals were homogeneously dispersed around the AlN grains of the matrix, the chemical corrosion resistance of AlN/nano-sized h-BN ceramic composites was higher than that of AlN/micro-sized h-BN ceramic composites and monolithic AlN ceramics. Due to the better hydrophobic property of h-BN, the AlN/BN composites had a better hydrophobic property than the monolithic AlN ceramic, at the same time, because of the homogeneous dispersion of the nano-BN, the creepage discharze voltage of AlN/nano-sized BN composites was the highest.

Utility of Readout-Segmented Echo-Planar Imaging-Based Diffusion Kurtosis Imaging for Differentiating Malignant from Benign Masses in Head and Neck Region

Gao Ma,Xiao-Quan Xu,Hao Hu,Guo-Yi Su,Jie Shen,Hai-Bin Shi,Fei-Yun Wu 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.3

Objective: To compare the diagnostic performance of readout-segmented echo-planar imaging (RS-EPI)-based diffusion kurtosis imaging (DKI) and that of diffusion-weighted imaging (DWI) for differentiating malignant from benign masses in head and neck region. Materials and Methods: Between December 2014 and April 2016, we retrospectively enrolled 72 consecutive patients with head and neck masses who had undergone RS-EPI-based DKI scan (b value of 0, 500, 1000, and 1500 s/mm2) for pretreatment evaluation. Imaging data were post-processed by using monoexponential and diffusion kurtosis (DK) model for quantitation of apparent diffusion coefficient (ADC), apparent diffusion for Gaussian distribution (Dapp), and apparent kurtosis coefficient (Kapp). Unpaired t test and Mann-Whitney U test were used to compare differences of quantitative parameters between malignant and benign groups. Receiver operating characteristic curve analyses were performed to determine and compare the diagnostic ability of quantitative parameters in predicting malignancy. Results: Malignant group demonstrated significantly lower ADC (0.754 ± 0.167 vs. 1.222 ± 0.420, p < 0.001) and Dapp (1.029 ± 0.226 vs. 1.640 ± 0.445, p < 0.001) while higher Kapp (1.344 ± 0.309 vs. 0.715 ± 0.249, p < 0.001) than benign group. Using a combination of Dapp and Kapp as diagnostic index, significantly better differentiating performance was achieved than using ADC alone (area under curve: 0.956 vs. 0.876, p = 0.042). Conclusion: Compared to DWI, DKI could provide additional data related to tumor heterogeneity with significantly better differentiating performance. Its derived quantitative metrics could serve as a promising imaging biomarker for differentiating malignant from benign masses in head and neck region.

An Orbital Design Method for Satellite Formation Flying

Hai-Ying Cui,Jun-Feng Li,Yun-Feng Gao 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.2

An orbital design method of the formation initialization based on the relative orbital element method is presented. It firstly constructed the relative motion equation of the satellite formation flying in terms of the leader and follower's orbital elements. Then the equation was simplified when the orbit eccentricity of the leader stellite was small. And according to the satellites' mission, a general design method for the relative trajectory was proposed. The advantage of this method is that one can get a very simple analytical formula of each follower satellite's orbital elements when the orbital eccentricity of the leader satellite is zero. The simulation results show that the method is effective.

An Orbital Design Method for Satellite Formation Flying

Hai-Ying Cui,Jun-Feng Li,Yun-Feng Gao 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.2

Active and Passive Smoking, and Alcohol Drinking and Breast Cancer Risk in Chinese Women

Gao, Chang-Ming,Ding, Jian-Hua,Li, Su-Ping,Liu, Yan-Ting,Qian, Yun,Chang, Jun,Tang, Jin-Hai,Tajima, Kazuo Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.2

To evaluate the relation between smoking, alcohol drinking and risk of breast cancer in Chinese women, we conducted a case-control study with 669 cases and 682 population-based controls in Jiangsu Province of China. A structured questionnaire was used to elicit detailed information. Unconditional logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs). The results revealed that smoking, whether active or passive through the husband, was related to increased risk of breast cancer. The ORs (adjusted for age, menopausal status, educational levels, occupation, body mass index and income) were 3.55 (95%CI: 1.27-9.91) for active smoking and 1.47 (95%CI: 1.18-1.84) for passive smoking from husbands, respectively. A significant positive relationship was observed between breast cancer risk and the degree of husbands' smoking. There were significant increase trend in ORs with the daily smoked number of cigarettes of husbands, the passive smoking years from husbands and the pack-years of husbands' smoking (trend test: p=0.00003, 0.00013 and 0.0001, respectively). Alcohol consumption was also found to be a risk factor. The findings of this study in particular suggest that husbands' smoking increases risk of breast cancer in Chinese women.

20(S)-Protopanaxadiol enhances angiogenesis via HIF-1α-mediated VEGF secretion by activating p70S6 kinase and benefits wound healing in genetically diabetic mice

Er-Yun Zhang,Bo Gao,Hai-Lian Shi,Ling-Fang Huang,Li Yang,Xiao-Jun Wu,Zheng-Tao Wang 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-

Impaired angiogenesis is one of the crucial factors that impede the wound healing process in diabetic foot ulcers (DFUs). In this study, we found that 20(S)-protopanaxadiol (PPD), an aglycone of ginsenosides in Panax notoginseng, stimulated angiogenesis and benefited wound healing in genetically diabetic mice. In HUVECs, PPD promoted cell proliferation, tube formation and VEGF secretion accompanied by increased nuclear translocalization of HIF-1α, which led to elevated VEGF mRNA expression. PPD activated both PI3K/Akt/mTOR and Raf/MEK/ERK signaling pathways in HUVECs, which were abrogated by LY294002 and PD98059. Furthermore, these two pathways had crosstalk through p70S6K, as LY294002, PD98059 and p70S6K siRNA abolished the angiogenic responses of PPD. In the excisional wound splinting model established in db/db diabetic mice, PPD (0.6, 6 and 60 mg ml− 1) accelerated wound closure, which was reflected by a significantly reduced wound area and epithelial gaps, as well as elevated VEGF expression and capillary formation. In addition, PPD activated PI3K/Akt/ERK signaling pathways, as well as enhanced p70S6K activity and HIF-1α synthesis in the wounds. Overall, our results revealed that PPD stimulated angiogenesis via HIF-1α-mediated VEGF expression by activating p70S6K through PI3K/Akt/mTOR and Raf/MEK/ERK signaling cascades, which suggests that the compound has potential use in wound healing therapy in patients suffering from DFUs.

An Orbital Design Method for Satellite Formation Flying

Cui Hai-Ying,Li Jun-Feng,Gao Yun-Feng The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.2

An orbital design method of the formation initialization based on the relative orbital element method is presented. It firstly constructed the relative motion equation of the satellite formation flying in terms of the leader and followers' orbital elements. Then the equation was simplified when the orbit eccentricity of the leader satellite was small. And according to the satellites' mission, a general design method for the relative trajectory was proposed. The advantage of this method is that one can get a very simple analytical formula of each follower satellite's orbital elements when the orbital eccentricity of the leader satellite is zero. The simulation results show that the method is effective.

Technique for Intrusion Detection based on Minkowsky Distance Negative Selection Algorithm

Niu Ling,Feng Gao-feng,Peng Hai-yun 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.12

Traditional negative selection algorithms often result in a number of black holes, which directly leads to the missing alarm drawback in the intrusion detection system. In order to settle the above problem, a novel negative selection algorithm based on Minkowsky distance is proposed. Firstly, the proposed algorithm computes the Minkowsky distance between the detectors. Then, compute the serial same numbers between the detector and self-set strings, which is helpful to improve the coverage area of the detector. Finally, the new detectors after training and renewal are put into the mature detector set to decline the number of black holes. Experimental results demonstrate that, compared with the traditional negative selection algorithms, the number of black holes and the missing alarm rate decline a lot in the proposed algorithm.