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Description to wear debris boundaries by radar graph fractal method

Chinese Science Bulletin 2007年第16期52卷 2285-2290页

作者： LIU HongTao1,2 & GE ShiRong1 1 Institute of Tribology and Reliability engineering,china university of mining & technology,xuzhou 221008,china 2 college of mechanical and electrical engineering,china university of mining & technology,xuzhou 221116,china Institute of Tribology and Reliability engineering China University of Mining & Technology Xuzhou China college of mechanical and electrical engineering China University of Mining & Technology Xuzhou China

In this paper,radar graph fractal method is introduced to describe wear debris boundaries. Research results show that it is a nice way to describe wear debris boundaries. Since the longest axis is selected as the first coordinate axis,its center point selected as the center point of the radar graph,and the co-ordinate value of wear debris boundary selected as the measure parameter,the limitations existing in Yard fractal measure method can be avoided. For any wear debris,its radar graph fractal dimension value is one and only,and as the wear debris shape changes from round to strip,the radar graph fractal dimension value also changes from low to high,showing strong uniqueness and independence. Due to the fact that the researched wear debris is gotten in different wear states,the results also prove that radar graph fractal dimension value is correlated with frictional pairs work condition and wear state. Radar graph fractal method is compared with Yard fractal measure methods,and results show that ra-dar graph fractal dimension values gotten from different wear debris have enough value grads to avoid effect of errors,and provide higher sensitivity for wear debris shape. This paper also discusses the influencing factors for radar graph fractal method. With the increase of the decomposing degree value,the radar graph fractal dimension tends to keep stable at one certain value,showing the typical characteristic of the fractal theory. All this proves that radar graph fractal method is an effective description method for wear debris boundaries.

关键词：磨粒边界雷达图表分形法

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Relations between thickness of UHMWPE’s wear debris and positive pressure of tribological system

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Chinese Science Bulletin 2008年第9期53卷 1435-1443页

作者： LIU HongTao1,2,3 & GE ShiRong1,3 1 Institute of Tribology and Reliability engineering, china university of mining & technology, xuzhou 221116, china 2 college of mechanical and electrical engineering, china university of mining & technology, xuzhou 221116, china 3 Biotribology Center, State Key Laboratory of Tribology, xuzhou 221116, china Institute of Tribology and Reliability engineering China University of Mining & Technology Xuzhou China college of mechanical and electrical engineering China University of Mining & Technology Xuzhou China Biotribology Center State Key Laboratory of Tribology Xuzhou China

MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler is introduced to research the relations be- tween thickness of UHMWPE’s wear debris and positive pressure of tribological system. Research re- sults show that thickness of wear debris owns evident classification, and the first grade thickness math model and the second grade thickness math model are built. By the second grade thickness math model, the true force condition in the tribological system can be gotten, and the model can be used as a tool to modify simulating parameters of the tribological system, and it is an important inspecting method to the airtight system which cannot be examined in real time. The first grade thickness math model can describe the true working load and surface condition of work piece in the tribological sys- tem, and is an effective description method for the running condition of frictional pairs. The research results at different lubricating conditions testify the relations between thicknesses of wear debris and positive pressure of the tribological system. The fractal relation between maximal thickness of wear debris and positive pressure is discussed. The conceptions of the immutability principle and charac- teristic granularity of wear debris thickness are brought forward and discussed. In conclusion, as a stable tribological parameter owning mechanical theory basis, wear debris thickness will play an im- portant part in fault diagnosis, especially for the airtight system such as artificial joint.

关键词：摩擦学磨损面厚度分形数学模型

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大倾角综采面液压支架稳定性分析

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陕西煤炭 2011年第4期30卷 34-35页

作者：陈洋李正韩志婷中国矿业大学机电工程学院江苏徐州221116 中国矿业大学矿业工程学院江苏徐州221116

通过对大倾角综采工作面液压支架与围岩的关系进行探讨,并对液压支架发生倾倒和下滑两方面进行受力分析,揭示了支架在大倾角工作面的稳定状况,并从综采工作面的布置、防倒防滑装置等方面提出了提高支架稳定性和支护可靠性的措施。

关键词：大倾角液压支架稳定性防倒防滑措施

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Effect of Preparation Methods on mechanical Properties of PVA/HA Composite Hydrogel

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Journal of Bionic engineering 2010年第3期7卷 235-243页

作者： Dekun Zhang~1, Junjie Duan~1, Dagang Wang~2, Shirong Ge~2 1. School of Materials Science and engineering, china university of mining and technology xuzhou 221116, P. R. china 2. School of mechanical and electrical engineering, china university of mining and technology, xuzhou 221116, P. R. china School of Materials Science and engineering China University of Mining and Technology Xuzhou P. R. China School of mechanical and electrical engineering China University of Mining and Technology Xuzhou P. R. China

Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2%, 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties were carried out todiscuss the influence of different contents of HA and freezing-thawing cycles on the mechanical properties of PVA/HA compositehydrogel. The results of static mechanical tests showed that the PVA/HA composite hydrogel with 3% HA and ninefreezing-thawing cycles had excellent stress relaxation properties, higher relaxation ratio, lower stress equilibrium value andpresented better properties of creep and recovery. The results of dynamic mechanical test showed that the PVA/HA compositehydrogel with nine freezing-thawing cycles had higher storage modulus and loss modulus, so was the PVA/HA compositehydrogel with 3% HA.

关键词： composite hydrogel HA contents freezing-thawing cycles static properties dynamic properties

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Transient temperature field of a friction pair in a HVD device of a belt conveyor

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mining Science and technology 2010年第6期20卷 904-907页

作者： XIE Fangwei, HOU Youfu School of mechanical and electrical engineering, china university of mining & technology, xuzhou 221008, china School of mechanical and electrical engineering China University of Mining & Technology Xuzhou 221008 China

To show the distribution of a temperature field on a steel disk and to prolong the service life of a friction pair in a Hy-dro-Viscous Drive (HVD) device, a theoretical model of a transient temperature field was established, based on the theory of heat conduction. This theoretical model was solved using a finite element method. The results show that the surface temperature of the steel disk does not increase consistently as a function of the radius; the highest temperature appears short of the maximum radius. The relationship between the surface temperature and the mixed friction time is exponential. With a friction time of 15 s, the tem-perature reached 465.9 °C. Simultaneously, the internal thermal stress is larger than the yield stress of the material, causing a warping deformation of the steel disk. The largest axial deformation is 0.32 mm. The results of the experiment suggest that the de-formation is the same as that obtained from numerical simulation. Therefore, deformation of the steel disk must be considered dur-ing the study of the characteristics of a HVD.

关键词： hydro-viscous steel disk temperature field deformation numerical simulation

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Research on the Long Time Swelling Properties of Poly (vinyl alcohol)/Hydroxylapatite Composite Hydrogel

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Journal of Bionic engineering 2009年第1期6卷 22-28页

作者： De-kun Zhang~(1,3), Da-gang Wang~2, Jun-jie Duan~(1,3), Shi-rong Ge~(2,3)1. School of Materials Science and engineering, china university of mining and technology, xuzhou 221116, P. R. china2. School of mechanical and electrical engineering, china university of mining and technology, xuzhou 221116, P. R. china3. Biotribology Center, National Key Laboratory of Tribology, Tsinghua university, Beijing 100083, P. R. china School of Materials Science and engineering China University of Mining and Technology Xuzhou P. R. China Biotribology Center National Key Laboratory of Tribology Tsinghua University Beijing P. R. China School of mechanical and electrical engineering China University of Mining and Technology Xuzhou P. R. China

Poly(vinyl alcohol)/hydroxylapatite(PVA/HA)composite hydrogel was prepared by repeated freezing and *** water loss properties of the resultant hydrogel were investigated by using optical *** time immersion tests of PVA/HA composite hydrogel were carried out in the diluted calf serum solution to study the change laws of swelling properties with the freezing-thawing cycles and HA *** micro-morphologies of PVA/HA composite hydrogel after long time immersion were observed by means of the high-accuracy 3D *** results show that the swelling process of PVA/HA composite hydrogel is the converse process of its water *** time swelling ratio curves of PVA/HA composite hydrogel in the calf serum solution are manifested as four stages of quick increase,decrease,slow decrease and stable balance,and its equilibrium swelling ratio decreases with the increase of freezing-thawing cycles and HA *** is revealed that the network structure of the composite hydrogel immersed for a long period is significantly improved with the increase of HA content. Perfect network structures of PVA/HA composite hydrogel as well as full and equilibrium tissues after swelling equilibrium are obtained when the HA content is 3% and the number of freezing-thawing cycles is 7.

关键词： poly (vinyl alcohol) hydroxyapatite composite hydrogel swelling property morphology

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Analysis on Tribological Properties of Potentially New Friction Material with Response Surface Method

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Journal of Wuhan university of technology(Materials Science) 2011年第3期26卷 499-503页

作者：徐蕾 School of mechanical and electrical engineering China University of Mining & Technology

The tribological properties of newly developed friction material were evaluated by statistical analysis of the major affecting *** material for investigation was non-metallic friction material synergistically reinforced with aramid fibre and CaSO 4 whisker,which was developed for hoisting applications in coal *** response surface method（RSM）was employed to analyze the material performances affected by the independent and interactive effect of the factors under the normal working condition and severe working condition,*** showed that under the normal working condition,the newly developed material exhibited stable tribological properties which were insensitive to the test *** under the severe working condition,the sliding velocity was the most dominant factor affecting the friction ***,compared to the commercially available material,the modified material showed superior wear resistance and thermal stability.

关键词： tribological properties friction material response surface method wear

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Kinetics analysis of volume phase transition of intelligent neutral thermo-sensitive hydrogels

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Science china(Physics,Mechanics & Astronomy) 2008年第5期51卷 532-540页

作者： WANG XiaoGui1 & LI YiQuan2 1 college of mechanical engineering,Zhejiang university of technology,Hangzhou 310032,china 2 School of mechanical & Electronic engineering,Changchun university of Science and technology,Changchun 130022,china college of mechanical engineering Zhejiang University of Technology Hangzhou China School of mechanical & Electronic engineering Changchun University of Science and Technology Changchun China

In this work,utilizing the first law of thermodynamics and the Flory mean-field theory,the kinetic deformation studies concerning the volume phase transition of the neutral thermo-sensitive hydrogels were performed *** hydrogel was assumed as a biphasic mixture medium in the framework of the continuum mixture *** the energy conservation of the thermodynamics system of the hydrogel,the governing equations for the kinetics of the nonlinear large deforma-tion were *** explicit analytical expressions of the effective stress tensor and the chemical potential of the fluid of the thermo-sensitive hydrogel PNIPA were also obtained from the Helmholtz free energy,which can model the steady-static volume phase transition quantitatively.

关键词： thermo-sensitive hydrogel volume phase transition effective stress energy conservation

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Control strategy for an intelligent shearer height adjusting system

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mining Science and technology 2010年第6期20卷 908-912页

作者： FAN Qigao, LI Wei, WANG Yuqiao, ZHOU Lijuan, YANG Xuefeng, YE Guo School of mechanical & electrical engineering, china university of mining & technology, xuzhou 221008, china School of mechanical & electrical engineering China University of Mining & Technology Xuzhou 221008 China

An intelligent shearer height adjusting system is a key technology for mining at a man-less working face. A control strategy for a shearer height adjusting system based on a mathematical model of the height adjusting mechanism is proposed. It considers the non-linearity and time variations in the control process and uses Dynamic Fuzzy Neural Networks （D-FNN）. The inverse characteristics of the system are studied. An adaptive on-line learning and error compensation mechanism guarantees sys- tem real-time performance and reliability. Parameters from a German Eickhoff SL500 shearer were used with Maflab/Simulink to simulate a height adjusting control system. Simulation shows that the trace error of a D-FNN controller is smaller than that of a PID controller. Also, the D-FNN control scheme has good generalization and tracking performance, which allow it to satisfy the needs of a shearer height adjusting system.

关键词： shearer height adjusting system dynamic fuzzy neural network

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Robust Stabilization Control for a Class of Nonlinear Measure Differential Systems with Delay

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Systems Science and Systems engineering 1998年第1期8卷 18-28页

作者： YUE Dong\ XU Shifan college of Information and electrical engineering china university of mining and technology xuzhou, Jiangsu,221008,china)

This paper considers the robust stabilization problem of a class of nonlinear measure differential systems with *** eliminate the effect of nonlinear uncertainties on the stability of a closed loop system, a nonlinear controller is *** addition, to get the stability result of closed loop dynamics, two novel lemmas are *** our approach, we do not require the assumption that the time varying delay variable γ(t) be restricted by (t)<1 , which is often required in many previous papers (e.g,see).

关键词： measure differential systems delay robust control stable

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