Spatial synchronization behavior of vibration system with tri-motor excitation

Pan Fang,Shuangquan Shi,Tao Chen,Min Zou,Duyu Hou,Zhiliang Zhang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9

The existing research of vibration synchronization among multiple rotors is mainly concentrated on plane vibration system. In this paper, the synchronization mechanism of the spatial vibration system actuated with tri-motor rotating in identical direction is studied. Firstly, the dynamic model is established, and the motion differential equations are deduced via Lagrange formulation. Then, small parameter average method is applied to explore the synchronization condition; Lyapunov equation and Routh-Hurwitz criterion are introduced to analyze the synchronization stability. Finally, the influence of the system parameter on synchronization is discussed by numerical calculation, and the electromechanical coupling simulation based on Matlab/Simulink is given to confirm the reliability of the theoretical analysis. The research result indicates that the vibration synchronization is affected by the horizontal distance between two coaxial motors, the installation height and the masses of three eccentric rotors (ERs), but the influence of the horizontal distance between coaxial motor and noncoaxial motor on synchronization is small.

Influences of seepage force and out-of-plane stress on cavity contracting and tunnel opening

Zou, Jin-Feng,Chen, Kai-Fu,Pan, Qiu-Jing Techno-Press 2017 Geomechanics & engineering Vol.13 No.6

The effects of seepage force and out-of-plane stress on cavity contracting and tunnel opening was investigated in this study. The generalized Hoek-Brown (H-B) failure criterion and non-associated flow rule were adopted. Because of the complex solution of pore pressure in an arbitrary direction, only the pore pressure through the radial direction was assumed in this paper. In order to investigate the effect of out-of-plane stress and seepage force on the cavity contraction and circular tunnel opening, three cases of the out-of-plane stress being the minor, intermediate, or major principal stress are assumed separately. A method of plane strain problem is adopted to obtain the stress and strain for cavity contracting and circular tunnel opening for three cases, respectively, that incorporated the effects of seepage force. The proposed solutions were validated by the published results and the correction is verified. Several cases were analyzed, and parameter studies were conducted to highlight the effects of seepage force, H-B constants, and out-of-plane stress on stress, displacement, and plastic radius with the numerical method. The proposed method may be used to address the complex problems of cavity contraction and tunnel opening in rock mass.

The GSTT1 Null Genotype Contributes to Increased Risk of Prostate Cancer in Asians: a Meta-analysis

Pan, Zhao-Jun,Huang, Wei-Jia,Zou, Zi-Hao,Gao, Xing-Cheng Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

Background: Many studies have investigated the association between glutathione S-transferase T 1 (GSTT1) null genotype and risk of prostate cancer, but the impact of GSTT1 null genotype in Asians is still unclear owing to inconsistencies across results. Thie present meta-analysis aimed to quantify the strength of the association between GSTT1 null genotype and risk of prostate cancer. Methods: We searched the PubMed, Embase and Wangfang databases for studies of associations between the GSTT1 null genotype and risk of prostate cancer in Asians and estimated summary odds ratio (OR) with their 95% confidence interval (95% CI). Results: A total of 11 case-control studies with 3,118 subjects were included in this meta-analysis, which showed the GSTT1 null genotype to be significantly associated with increased risk of prostate cancer in Asians (random-effects OR = 1.49, 95% CI 1.15-1.92, P = 0.002), also after adjustment for heterogeneity (fixed-effects OR = 1.45, 95% CI 1.23-1.70, P < 0.001). No evidence of publication bias was observed. Conclusions: This meta-analysis of available data suggested the GSTT1 null genotype does contribute to increased risk of prostate cancer in Asians.

Study on synchronization characteristics for self-synchronous vibration system with dual-frequency and dual-motor excitation

Min Zou,Pan Fang,Huan Peng,Duyu Hou,Mingjun Du,Yongjun Hou 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In petroleum drilling engineering, drilling shakers are critical devices for cleansing solid particles and recycling drilling fluid. For the problem that the vibration screen with a single frequency usually results in flurry overflow due to the blocking of screen mesh, a selfsynchronous vibratory system with dual-frequency and dual-motor excitation is proposed. But it is not clear about the synchronization mechanism and dynamic characteristics of the system, which causes a lack of theoretical description for the source of synchronization phenomenon. Hence, this paper explores the synchronization mechanism and dynamic characteristics around the proposed system above. First, vibration and stability theory are employed to master the dynamic characteristics of the system, and the dynamic model is established by Lagrange equation. Then, displacement responses of the system are obtained by dimensionless formulas. Synchronous condition and synchronous stability between the unbalanced rotors are derived with small parameter method and Poincare method. Finally, some computer simulations are implemented to further verify the correctness of the theoretical analysis. The research result shows that the synchronous ability between the two unbalanced rotors actuated by dual-frequency excitation is related to the distance from the rotating center of the motor to the centroid of supporting body, and the greater the distance value, the better the synchronization of the vibrating system. This study will promote the recycle technology development of drilling fluid and settlement of the common scientific issues in vibrating synchronization.

A Campus Community-based Mobility Model for Routing in Opportunistic Networks

( Daru Pan ),( Min Fu ),( Jiajia Sun ),( Xin Zou ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.3

Mobility models are invaluable for determining the performance of routing protocols in opportunistic networks. The movement of nodes has a significant influence on the topological structure and data transmission in networks. In this paper, we propose a new mobility model called the campus-based community mobility model (CBCNM) that closely reflects the daily life pattern of students on a real campus. Consequent on a discovery that the pause time of nodes in their community follows a power law distribution, instead of a classical exponential distribution, we abstract the semi-Markov model from the movement of the campus nodes and analyze its rationality. Then, using the semi-Markov algorithm to switch the movement of the nodes between communities, we infer the steady-state probability of node distribution at random time points. We verified the proposed CBCNM via numerical simulations and compared all the parameters with real data in several aspects, including the nodes` contact and inter-contact times. The results obtained indicate that the CBCNM is highly adaptive to an actual campus scenario. Further, the model is shown to have better data transmission network performance than conventional models under various routing strategies.

Metathetic Degradation of Styrene-Butadiene Rubber via Ru-Alkylidene Complex Catalyzed Reaction

Tingting Zou,Bin Jiang,Shaohui Lin,Qinmin Pan 한국고분자학회 2016 폴리머 Vol.40 No.5

Metathetic degradation and functionalization of styrene-butadiene rubber (SBR) were performed with allyl hexanoate, allyl chloroacetate, 5-hexenyl acetate and trifluoroethyl methacrylate as chain transfer agents (CTAs) using Grubbs 2<SUP>nd</SUP> generation catalyst. It has been demonstrated that the catalyst concentration, CTA concentration and reaction time were major factors influencing the molecular weights and polydispersity indices of targeted telechelic SBR oligomers. Well-defined oligomers with molecular weights ranging from 700 to 36600 g mol<SUP>-1</SUP> and polydispersity indices ranging from 1.17 to 4.79 were realized. The structures of the SBR oligomers were determined by FTIR and <SUP>1</SUP>H NMR analyses, which indicated that the functional groups of the CTAs were successfully attached onto the end of the polymer chains. To further investigate the performance of SBR oligomers, differential scanning calorimetry (DSC) analysis was performed, which indicated that the glass transition temperature (Tg) of the metathesis products decreased with longer reaction time.

SYNTHESIS AND CHARACTERIZATION OF AU NANOPARTICLES/REDUCED GRAPHENE OXIDE NANOCOMPOSITE: A FACILE AND ECO-FRIENDLY APPROACH

MEILING ZOU,HAN ZHU,PAN WANG,MINGLIANG DU,MING ZHANG,SHIYONG BAO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.3

In this paper, epigallocatechin gallate (EGCG) was used as a green reductant both for thefabrication of soluble reduced graphene oxide (rGO) and the synthesis of Au nanoparticles/rGOnanocomposite. Fourier transform infrared (FTIR) spectra con¯rmed the e±cient removal of theoxygen-containing groups in graphene oxide (GO) through the reduction act of EGCG. Aunanoparticles (AuNPs) were anchored onto the rGO sheets by heating the mixed solution of rGOand chloroauric acid at 65?C using EGCG as reductant. Transmission electron microscopy(TEM), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) wereemployed to characterize the resulting nanocomposite. Due to the chelating e®ect of polyhydroxyEGCG, AuNPs with diameters of ? 20 – 50 nm were stably decorated onto both sides of the rGOsheets. Because this reduction method avoids the use of toxic reagents, AuNPs/rGO nano-composite would be eco-friendly, and it might be useful not only for electronic devices but also forbiocompatible materials in the future applications.

Query with SUM Aggregate Function on Encrypted Floating-Point Numbers in Cloud

Zhu, Taipeng,Zou, Xianxia,Pan, Jiuhui Korea Information Processing Society 2017 Journal of information processing systems Vol.13 No.3

Cloud computing is an attractive solution that can provide low cost storage and powerful processing capabilities for government agencies or enterprises of small and medium size. Yet the confidentiality of information should be considered by any organization migrating to cloud, which makes the research on relational database system based on encryption schemes to preserve the integrity and confidentiality of data in cloud be an interesting subject. So far there have been various solutions for realizing SQL queries on encrypted data in cloud without decryption in advance, where generally homomorphic encryption algorithm is applied to support queries with aggregate functions or numerical computation. But the existing homomorphic encryption algorithms cannot encrypt floating-point numbers. So in this paper, we present a mechanism to enable the trusted party to encrypt the floating-points by homomorphic encryption algorithm and partial trusty server to perform summation on their ciphertexts without revealing the data itself. In the first step, we encode floating-point numbers to hide the decimal points and the positive or negative signs. Then, the codes of floating-point numbers are encrypted by homomorphic encryption algorithm and stored as sequences in cloud. Finally, we use the data structure of DoubleListTree to implement the aggregate function of SUM and later do some extra processes to accomplish the summation.

Synchronous characteristic of three homodromy motors in vibrating isolation system

Yongjun Hou,Huan Peng,Pan Fang,Min Zou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.1

This paper researched the synchronous characteristic of three homodromy motors in a secondary isolation system. Firstly, the motion differential equations of the system were established via employing Lagrange’s equation. The Laplace transform was used to deduce approximate solutions of displacement. Next, the ability of vibrating isolation was determined through amplitude ratio. Secondly, the synchronous condition and steady criterion was obtained via employing the average small parameters method and Lyapunov criterion. And then the influence of structural parameters of the system on synchronous ability was analyzed. Moreover, the synchronous characteristics of the system, including the difference of residual torque among induction motors, the synchronous ability, the output torque of motors and the stable phase difference, were discussed through numerical analyses. Finally, the accuracy of theoretical analyses was proved through computer simulation results. It is shown that, the ability of vibrating isolation is principally impacted by vertical spring stiffness; the greater the installation distance among three motors, the easier to achieve synchronous motion of the rotors;meanwhile, the output torque of asynchronous motors is affected by the synchronous state of the vibrating system; the synchronous characteristic is mainly affected by the mounting dip angle of motors and the installation distance among motors. The research results can promote development of vibration engineering and related fields.

TEMPLATE STRATEGY FOR THE SYNTHESIS OF Cu2O-Pt HIERARCHICAL HETEROSTRUCTURES FOR THE DEGRADATION OF METHYLENE BLUE

SHIYONG BAO,HAN ZHU,PAN WANG,MEILING ZOU,MINGLIANG DU,MING ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.6

A facile and green route was introduced to synthesize Pt nanoparticles (PtNPs) immobilized on Cu2O octahedrons to form Cu2O–Pt hierarchical heterostructure. Transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were employed to study their morphology, chemical and crystallographic properties of the Cu2O–Pt hierarchical heterostructure. These novel Cu2O–Pt hierarchical heterostructures show fascinating degradations of methylene blue (MB), due to the suppressed electron/hole recombination phenomena and the efficient ability to capture the light.