Influence of different parameters on nonlinear friction-induced vibration characteristics of water lubricated stern bearings

Lin Chang-Gang,Zou Ming-Song,Zhang Hai-Cheng,Qi Li-Bo,Liu Shu-Xiao 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

To investigate the mechanism of friction-induced vibration and noise of ship water lubricated stern bearings, a two-degree-of-freedom (2-DOF) nonlinear self-excited vibration model is established. The novelty of this work lies in the detailed analysis of influence of different parameters on the stability and nonlinear vibration characteristics of the system, which provides a theoretical basis for the various friction vibration and noise phenomenon and has a very important directive meaning for low noise design of water lubricated stern bearings. The results reveal that the change of any parameter, such as rotating speed of shaft, contact pressure, friction coefficient, system damping and stiffness, has an important influence on the stability and nonlinear response of the system. The vibration amplitudes of the system increase as (a) rotating speed of shaft, contact pressure, and the ratio of static friction coefficient to dynamic friction coefficient increase and (b) the transmission damping between motor and shaft decreases. The frequency spectrum of the system is modulated by the first mode natural frequency, which is continuous multi-harmonics of the first mode natural frequency. The response of the system presents a quasi-periodic motion.

Themed issue on perovskite solar cells

Lin, Zhiqun,Park, Nam-Gyu,Li, Gang The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.17

<P>Guest editors Zhiqun Lin, Nam-Gyu Park and Gang Li introduce this <I>Journal of Materials Chemistry A</I> themed issue on perovskite solar cells.</P>

Production of Nitric Oxide under Ultraviolet-B Irradiation is Mediated by Hydrogen Peroxide through Activation of Nitric Oxide Synthase

( Lin Gang Zhang ),( Li Qun Zhao ) 한국식물학회 2008 Journal of Plant Biology Vol.51 No.6

A Study on Shape and Height of Shipwaves

Song-lin Gang,Mi-Kum Kim,Chang-Je Kim 한국항해항만학회 2009 한국항해항만학회지 Vol.33 No.2

Shipwaves can have harmful effects on ships working on the sea. in a harbour or navigational channel and caused beach erosion, seawall destruction. This study aims to investigate describe the characteristics of the wave pattern generated by an individual model ship tested at different velocities and hull forms for a given water depth and to investigate the variations at a given distance from the sailing line under the same conditions. As a result, the angles a's by model ship tests are smaller than those by real ship ones. Wave heights decreases with an increasing the mid-ship cross sectional area As. The maximum wave height and period increase rapidly in the sabcritical speed, and beyond the critical speed the height and period decrease with increasing depth Froude number. And the period keeps constant with the distance from the sailing line.

Rock-breaking analysis model of new drill bit with tornado-like bottomhole model

Jia-lin Tian,Chang-fu Yuan,Lin Yang,Chuan-hong Fu,Gang Liu,Zhi Yang,Chun-ming Wu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.4

For improving the rock-breaking efficiency of oil and gas drill bits, a new drill bit is presented with tornado-like bottomhole model(named swirling cutting bit). The new drill bit cutter breaks rock with shocking and cutting effect during the drilling process, and theelements on largest ring cross the borehole center with high speed. It can effectively improve the center rock-breaking efficiency. Meanwhile,for all cutters on different rings breaking rock at the same time, it can optimize the rock-breaking volume of each element andimprove the bit service life. To analyze the interaction features between cutters and rock, the position equations are established by thecylindrical coordinates and complex movement principles, and then the velocity and acceleration equations can be obtained. Based on thenumerical example results, this paper analyzes the bottomhole model, the contact section, and the distribution features of velocities andaccelerations on different rings. By analyzing the acceleration results, we can study the failure mechanism of cutters. At the same time,lab experiments test the bottomhole model and rock-breaking features, and it verifies the accuracy of calculation method and equations. Moreover, the analysis method and models are also applicable to other types of bits or composite bits, and the inputting parameters needcorresponding adjustment for different type of bits.

Vibration analysis of new drill string system with hydro-oscillator in horizontal well

Jia-lin Tian,Zhi Yang,You Li,Lin Yang,Chun-ming Wu,Gang Liu,Chang-fu Yuan 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6

With the growth of oil and gas resource demand, the hydro-oscillator is widely used to enhance the Rate of penetration (ROP) and improve the efficacy in drilling various wells. The vibration model is the key issue of dynamics analysis and optimization of downhole tools. For the vibration analysis of the new drill string system with hydro-oscillator in the horizontal well, based on the design of the new hydro-oscillator and its operation conditions, the kinematics expressions are presented. Combined with the vibration force calculation results of the hydro-oscillator, the dynamics model of the new drill string system is established. Furthermore, the important features of vibration frequency, displacement, velocity and acceleration are discussed in the numerical example calculation results. By comparing the results of the calculation and experiment test, we can verify the correctness of the analysis model. With the hydro-oscillator vibration effect, the static friction between the drill string and wellbore is changed to the dynamic friction, so it can result in a significant increase in run length. At the same time, the ROP can be enhanced with the vibration effect. Moreover, with the parameters’ adjustment according to the operation conditions, the analysis method and model can also provide references to the study of similar downhole tools dynamics or mechanical properties.

Using the Lymph Node Ratio to Evaluate the Prognosis of Stage II/III Breast Cancer Patients Who Received Neoadjuvant Chemotherapy and Mastectomy

San-Gang Wu,Qun-Li Zeng,Juan Zhou,Jia-Yuan Sun,Fengyan Li,Qin Lin,Huan-Xin Lin,Xun-Xing Gaun,Zhen-Yu He 대한암학회 2015 Cancer Research and Treatment Vol.47 No.4

Purpose This study was conducted to investigate the prognostic value of lymph node ratio (LNR) instage II/III breast cancer patients who undergo mastectomy after neoadjuvant chemotherapy. Materials and MethodsClinical and pathological data describing stage II/III breast cancer patients were includedin this retrospective study. The primary outcomes were locoregional recurrence-free survival(LRFS), distant metastasis-free survival (DMFS), disease-free survival (DFS), and overallsurvival (OS). ResultsAmong 277 patients, there were 43 ypN0, 64 ypN1, 89 ypN2, and 81 ypN3 cases. Additionally, there were 43, 57, 92 and 85 cases in the LNR 0, 0.01-0.20, 0.21-0.65, and> 0.65 groups, respectively. The median follow-up was 49.5 months. Univariate analysisshowed that both ypN stage and LNR were prognostic factors of LRFS, DMFS, DFS, and OS(p < 0.05). Multivariate analysis showed that LNR was an independent prognostic factor ofLRFS, DMFS, DFS, and OS (p < 0.05), while ypN stage had no effect on prognosis (p > 0.05). ConclusionThe integrated use of LNR and ypN may be suitable for evaluation the prognosis of stageII/III breast cancer patients who undergo mastectomy after neoadjuvant chemotherapy.

Professionals’ experiences and attitudes toward use of Traditional Chinese Medicine in hospice palliative inpatient care units: A multicenter survey in Taiwan

Yu-Jia Lin,Hsiao-Ting Chang,Ming-Hwai Lin,Ru-Yih Chen,Ping-Jen Chen,Wen-Yuan Lin,Jyh-Gang Hsieh,Ying-Wei Wang,Chung-Chieh Hu,Yi-Sheng Liou,Tai-Yuan Chiu,Chun-Yi Tu,Yi-Jen Wang,Bo-Ren Cheng,Tzeng-Ji Ch 한국한의학연구원 2021 Integrative Medicine Research Vol.10 No.2

Background: Medical staff may have difficulties in using conventional medicine to manage symptoms among terminally ill patients, including adverse effects of the treatment. Traditional Chinese medicine (TCM) is regarded as a complementary or alternative medicine, and has been increasingly used in the field of palliative medicine in recent years. This study aimed to investigate the experiences of and attitudes toward using TCM among palliative care professionals, and to provide preliminary information about its use in palliative care. Methods: This was a cross-sectional survey study conducted in eight inpatient hospice wards in Taiwan between December 2014 and February 2016. The questionnaire was self-administered, and was analyzed with descriptive statistics including Pearson’s Chi-square test and Fisher’s exact test. Results: A total of 251 palliative care professionals responded to the questionnaire, of whom 89.7% and 88.9% believed that the use of TCM could improve the physical symptoms and quality of life in terminally ill patients, respectively. Overall, 59.8%, of respondents suggested that TCM had rare side effects, and 58.2% were worried that TCM could affect the liver and kidney function of patients. In total, 89.7% and 88.0% of professionals agreed there were no suitable clinical practice guidelines and educational programs, respectively, for TCM use in palliative care. Conclusions: Most of the respondents agreed there was insufficient knowledge, skills-training, and continuing education on the use of TCM in terminally ill patients in Taiwan. These results show that to address patient safety considerations, guidelines about use of TCM in palliative care should be established.

Assessment of the crest cracks of the Pubugou rockfill dam based on parameters back analysis

Zhou, Wei,Li, Shao-Lin,Ma, Gang,Chang, Xiao-Lin,Cheng, Yong-Gang,Ma, Xing Techno-Press 2016 Geomechanics & engineering Vol.11 No.4

The crest of the Pubugou central core rockfill dam (CCRD) cracked in the first and second impounding periods. To evaluate the safety of the Pubugou CCRD, an inversion analysis of the constitutive model parameters for rockfill materials is performed based on the in situ deformation monitoring data. The aim of this work is to truly reflect the deformation state of the Pubugou CCRD and determine the causes of the dam crest cracks. A novel real-coded genetic algorithm based upon the differences in gene fragments (DGFX) is proposed. It is used in combination with the radial based function neural network (RBFNN) to perform the parameters back analysis. The simulated settlements show good agreements with the monitoring data, illustrating that the back analysis is reasonable and accurate. Furthermore, the deformation gradient of the dam crest has been analysed. The dam crest has a great possibility of cracking due to the uncoordinated deformation, which agrees well with the field investigation. The deformation gradient decreases to the value lower than the critical one and reaches a stable state after the second full reservoir.

Angelica sinensis Supercritical Fluid CO2 Extract Attenuates D-Galactose-Induced Liver and Kidney Impairment in Mice by Suppressing Oxidative Stress and Inflammation

Zhi-Zhun Mo,Zhi-Xiu Lin,ZiRen Su,Lin Zheng,Hui-Lin Li,JianHui Xie,Yan-Fang Xian,Tie-Gang Yi,Shui-Qing Huang,Jian-Ping Chen 한국식품영양과학회 2018 Journal of medicinal food Vol.21 No.9

Angelica sinensis (AS, Danggui in Chinese) is an important herbal component of various traditional formulae for the management of asthenia and its tonic effects. Although AS has been shown to ameliorate cognitive damage and nerve toxicity in D-galactose (D-gal)-elicited senescent mice brain, its effects on liver and kidney injury have not yet been explored. In this work, mice were subjected to hypodermic injection with D-gal (200 mg/kg) and orally gavaged with AS (20, 40, or 80 mg/kg) once a day for 8 successive weeks. Results revealed that AS significantly improved liver and kidney function as assessed by organ index and functional parameters. In addition, AS pretreatment effectively ameliorated the histological deterioration. AS attenuated the MDA level and markedly enhanced the activities and gene expressions of antioxidative enzymes, namely Cu, Zn-SOD, CAT, and GPx. Furthermore, AS markedly inhibited the D-gal-mediated increment of expressions of inflammatory cytokines iNOS, COX-2, IκBα, p-IκBα, and p65 and promoted the IκBα expression level in both hepatic and renal tissues. In sum, AS pretreatment could effectively guard the liver and kidney of mice from D-gal-induced injury, and the underlying mechanism was deemed to be intimately related to attenuating oxidative response and inflammatory stress.