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Normal Force and Sag Resistance of Pipe Conveyor

Chinese Journal of Mechanical Engineering 2020年第3期33卷 60-71页

作者： Shuaiping Guo Wei Huang xuejun li Engineering Research Center of Advanced Mining Equipment Ministry of Education Hunan University of Science and TechnologyXiangtan 411201China Jiangsu Key Laboratory of Mine Mechanical and Electrical Equipment China University of Mining and TechnologyXuzhou 221116China.

Pipe belt conveyor is a new type of environmentally friendly and efficient bulk conveying *** the design of the roller,the belt and the driving motor of pipe belt conveyor,the sag resistance is a key ***,the normal force between the conveyor belt and the roller group is the other important factor need be considered and has a great influence on the sag *** paper analyzes a pipe belt conveyor with a diameter of 150 mm to study the calculation method of normal *** the relationship between the normal force and the sag resistance is ***,the normal force is decomposed into three components related to the forming force of belt,material gravity and belt *** it can be expressed as a linear combination of these three quantities,and the coefficients of each component are obtained based on the dynamic analysis of *** results show that the coefficient is mainly affected by the material filling rate,and is almost not affected by the distance between the rollers and the density of the *** calculation method of the normal force is eventually ***,the normal force in the case of different material filling rates is tested by experiments,and the calculation method of the normal force is ***,the variation law of the sag resistance in the case of different roller group spacing and material filling rate is studied by the dynamic *** is found that the roller group spacing and material filling rate affects the sag resistance by changing the normal *** is a power function relationship between the sag resistance and the normal *** the case of different roller group spacing and material filling rate,the relationship among the sag resistance and the normal force remains *** study results are of great significance to the design of pipe belt conveyor.

关键词： Pipe conveyor FEM Normal force Sag resistance

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Effects of HMW-GS Dx2 absence on the protein aggregation characteristics and thermal stability of wheat flour during maturation

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Food Quality and Safety 2023年第2期7卷 338-347页

作者： liye Zhao lijun Song liqun li xuejun li StateKey Laboratory of Crop Stress Biology in Arid Areas and College of Agronomy Northwest A&F UniversityYanglingChina Biotechnology Branch Xinjiang Agricultural Vocational Technical CollegeChangjiChina College of Horticulture State Key Laboratory of North China Crop Improvement and RegulationHebei Agricultural UniversityBaodingChina

Background:Wheat flour maturation affects the aggregation and structural stability of *** number of high-molecular-weight glutenin subunits(HMW-GSs)differs in various wheat *** effects of Dx2 absence on the protein aggregation characteristics and thermal sta-bility of flour were investigated during 120 d of maturation using near-isogenic lines(NILs).Results:The absence of Dx2 delayed and decreased the protein aggregation of flours during maturation,*** maturation-induced increases were later and smaller for glutenin,glutenin macropolymer(GMP),glutenin/gliadin ratio,β-sheets,andβ-sheet/a-helix ratio in HMW-D1a without Dx2 than in HMW-D1p with Dx2;these differences were ascribed to the weaker interactions between the sulfhydryl(-SH)groups,disulfide bonds(-S-S-),and hydrophobicity in the flours without *** maturation caused the dough microstructures to be more compact and denser,thereby increasing the flour thermal stability as observed by a higher denaturation peak temperature(Tp),enthalpy of thermal transition(△H),and degradation temperature(Td),These changes led to better dough properties such as dough development time,dough stability time,and protein weakening,but the optimal stage in HMW-D1a without Dx2was reached ***:These findings deepen the understanding of how HMW-GS Dx2 modifies protein structures during flour maturation.

关键词： Dx2 absence disulfide bond glutenin macropolymer secondary and micro structures thermal stability wheat flour maturation

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Effects of Unbalance Location on Dynamic Characteristics of High-speed Gasoline Engine Turbocharger with Floating Ring Bearings

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Chinese Journal of Mechanical Engineering 2016年第2期29卷 271-280页

作者： WANG Longkai BIN Guangfu li xuejun liU Dingqu Health Maintenance for Mechanical Equipment Key Lab of Hunan Province Hunan University of Science and Technology

For the high-speed gasoline engine turbocharger rotor, due to the heterogeneity of multiple parts material, manufacturing and assembly errors, running wear in impeller and uneven carbon of turbine, the random unbalance usually can be developed which will induce excessive rotor vibration, and even lead to nonlinear vibration accidents. However, the investigation of unbalance location on the nonlinear high-speed turbocharger rotordynamic characteristics is less. In order to discuss the rotor unbalance location effects of turbocharger with nonlinear floating ring bearings（FRBs）, the realistic turbocharger of gasoline engine is taken as a research object. The rotordynamic equations of motion under the condition of unbalance are derived by applied unbalance force and nonlinear oil film force of FRBs. The FE model of turbocharger rotor-bearing system is modeled which includes the unbalance excitation and nonlinear FRBs. Under the conditions of four different applied locations of unbalance, the nonlinear transient analyses are performed based on the rotor FEM. The differences of dynamic behavior are obvious to the turbocharger rotor systems for four conditions, and the bifurcation phenomena are different. From the results of waterfall and transient response analysis, the speed for the appearance of fractional frequency is not identical and the amplitude magnitude is different from the different unbalance locations, and the non-synchronous vibration does not occur in the turbocharger and the amplitude is relative stable and minimum under the condition 4. The turbocharger vibration and non-synchronous components could be reduced or suppressed by controlling the applied location of unbalance, which is helpful for the dynamic design, fault diagnosis and vibration control of the high-speed gasoline engine turbochargers.

关键词： high-speed turbocharger unbalance location nonlinear transient analysis waterfall dynamic characteristics

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Effects of Floating Ring Bearing Manufacturing Tolerance Clearances on the Dynamic Characteristics for Turbocharger

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Chinese Journal of Mechanical Engineering 2015年第3期28卷 530-540页

作者： WANG Longkai BIN Guangfu li xuejun ZHANG Xuefeng Health Maintenance for Mechanical Equipment Key Lab of Hunan Province Hunan University of Science and Technology Xeca Turbo Technologies(Beijing) Co. Ltd.

The inner and outer oil film dynamic characteristic coefficients of floating ring bearings（FRBs） change due to the manufacturing tolerance of the floating ring, journal and intermediate, which leads to high-speed turbocharger＇s vibration too large and even causes nonlinear vibration accident. However, the investigation of floating ring bearing manufacturing tolerance clearance on the rotordynamic characteristics is less at present. In order to study the influence law of inner and outer clearance on turbocharger vibration, the rotor dynamic motion equations of turbocharger supported in FRBs are derived by analyzing the size relations between floating ring, journal and intermediate for the inner and outer oil film clearances, the time transient response analysis for combination of FRBs clearance are developed. A realistic turbocharger is taken as a research object, the FE model of the turbocharger with FRBs is modeled. Under the conditions of four kinds of limit state bearing clearances for inner and outer oil film, the nonlinear transient analyses are performed based on the established FE dynamic models of the nonlinear rotor-FRBs system applied incentive combinations of gravity and unbalance force, respectively. From the waterfall, the simulation results show that the speed for the appearance of fractional frequency is not identical and the amplitude magnitude is different under the four kinds of bearing manufacturing tolerance limit clearances, and fractional frequency does not appear in the turbocharger and the amplitude is minimum under the ODMin/IDMax bearing manufacturing tolerance clearances. The turbocharger vibration is reduced by controlling the manufacturing tolerance clearance combinations of FRBs, which is helpful for the dynamic design and production-manufacturing of high-speed turbocharger.

关键词： turbocharger floating ring bearing manufacturing tolerance clearance nonlinear transient analysis dynamic characteristics

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Weighted Multi-sensor Data Level Fusion Method of Vibration Signal Based on Correlation Function

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Chinese Journal of Mechanical Engineering 2011年第5期24卷 899-904页

作者： BIN Guangfu JIANG Zhinong li xuejun DHILLON B S Diagnosis and Self-recovery Engineering Research Center Beijing University of Chemical Technology Beijing 100029 China Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment Hunan University of Science and Technology Xiangtan 411201 China Department of Mechanical Engineering University of Ottawa 161 Louis Pasteur Ottawa K1B 6N5 Canada

As the differences of sensor＇s precision and some random factors are difficult to control,the actual measurement signals are far from the target signals that affect the reliability and precision of rotating machinery fault *** traditional signal processing methods,such as classical inference and weighted averaging algorithm usually lack dynamic adaptability that is easy for trends to cause the faults to be misjudged or left *** enhance the measuring veracity and precision of vibration signal in rotary machine multi-sensor vibration signal fault diagnosis,a novel data level fusion approach is presented on the basis of correlation function analysis to fast determine the weighted value of multi-sensor vibration *** approach doesn＇t require knowing the prior information about sensors,and the weighted value of sensors can be confirmed depending on the correlation measure of real-time data tested in the data level fusion *** gives greater weighted value to the greater correlation measure of sensor signals,and vice *** approach can effectively suppress large errors and even can still fuse data in the case of sensor failures because it takes full advantage of sensor＇s own-information to determine the weighted ***,it has good performance of anti-jamming due to the correlation measures between noise and effective signals are usually *** the simulation of typical signal collected from multi-sensors,the comparative analysis of dynamic adaptability and fault tolerance between the proposed approach and traditional weighted averaging approach is ***,the rotor dynamics and integrated fault simulator is taken as an example to verify the feasibility and advantages of the proposed approach,it is shown that the multi-sensor data level fusion based on correlation function weighted approach is better than the traditional weighted average approach with respect to fusion precision and dynamic ***,the approac

关键词： vibration signal multi-sensor data level fusion correlation function weighted value

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Direct model reference adaptive control using K_p = LDU factorization for multivariable discrete-time plants

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控制理论与应用（英文版） 2008年第4期6卷 392-398页

作者： Junling li xuejun XIE Wei CHEN Institute of Automation Qufu Normal University Qufu Shandong 273165 China

For a large class of discrete-time multivariable plants with arbitrary relative degrees, the design and analysis of the direct model reference adaptive control scheme are investigated under less restrictive assumptions. The algorithm is based on a new parametrization derived from the high frequency gain matrix factorization Kp=LDU under the condition that the signs of the leading principal minors of/fp are known. By reproving the discrete-time Lp and L2σ norm relationship between inputs and outputs, establishing the properties of discrete-time adaptive law, defining the normalizing signal, and relating the signal with all signals in the closed-loop system, the stability and convergence of the discrete-time multivariable model reference adaptive control scheme are analyzed rigorously in a systematic fashion as in the continuous-time case.

关键词： Discrete-time systems Swapping lemma L2σ-nonn Normalizing signal Model reference adaptive control

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FINITE DEFORMATION ELASTO-PLASTIC THEORY AND CONSISTENT ALGORITHM

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Acta Mechanica Solida Sinica 2001年第1期14卷 31-40页

作者： liu xuejun li Mingrui Huang Wenbin Applied Mechanics Workshop China Agricultural UniversityEast Campus Beijing 100083 China Applied Mechanics Workshop China Agricultural UniversityEast Campus Beijing 100083 China Applied Mechanics Workshop China Agricultural UniversityEast Campus Beijing 100083 China

By using the logarithmic strain, the finite deformation plastic theory, corresponding to the infinitesimal plastic theory, is established successively. The plastic consistent algorithm with first order accuracy for the finite element method (FEM) is developed. Numerical examples are presented to illustrate the validity of the theory and effectiveness of the algorithm.

关键词： finite element finite deformation elasto-plasticity consistent algorithm

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Crystal Growth and Crystallization Time Scales of the Panzhihua Layered Intrusion:Constraint from Crystal Size Distribution

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1428-1439页

作者： li xuejun LUO Zhaohua li Xiaowei WANG Yu YANG Zongfeng li Jie liU Xiao State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China

The Panzhihua layered intrusions is generated closely related to the Emeishan *** paper analyzes the spatial distribution of plagioclase and *** quantitative texture analysis of 2209 plagioclase shows that the characteristic length of plagioclase is 0.54 to 0.96 mm,the intercept variation range is large,from-0.67 to 0.96,and the slope is-1.85 to-1.04,the Aspect Ratio shows from 1.84 to 2.59 and fractal dimension D is 1.908–*** quantitative texture analysis of 2342 pyroxene shows that the characteristic length of pyroxene is 0.38–0.64 mm,the intercept shows from 0.46 to 2.26,The slope ranges from-2.6 to-1.47,the Aspect Ratio value varies from 1.53 to 1.71,the fractal dimension D is 0.93 to *** the CSDs results of the Panzhihua intrusions indicate that plagioclase and pyroxene form in an open magma system and undergo four replenishment of magma *** plagioclase crystals do not grow as the lathlike shape,and the fractal growth leads to complex crystal *** plagioclase undergoes deformation compaction during the crystal process,and then is *** pyroxene crystals grow along an approximately triaxial ratio and undergo texture adjustment and small crystal dissolution *** all crystals in magma system grows up to 2 mm,the pyroxene undergoes cumulation in the Panzhihua layered *** plagioclase crystallization time scale is 171.23–304.41 years,representing that the crystallization is the more uniform in central part of the *** nucleation density continuously increases during the crystallization process of the magma *** time scale to reach the final maximum crystal nucleation density is 15.28–58.98 years.

关键词： crystal size distribution crystallization time scales layered intrusions Emeishan large igneous province Panzhihua

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An adaptive data-driven method for accurate prediction of remaining useful life of rolling bearings

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Frontiers of Mechanical Engineering 2018年第2期13卷 301-310页

作者： Yanfeng PENG Junsheng CHENG Yanfei liU xuejun li Zhihua PENG State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha 410082 China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082 China Hunan-Provincial Key Laboratory of Health Maintenance for Mechanical Equipment Hunan University of Science and Technology Xiangtan 411201 China School of Mathematics and Physics University of South ChinaHengyang 421001 China

A novel data-driven method based on Gaussian mixture model （GMM） and distance evaluation technique （DET） is proposed to predict the remaining useful life （RUL） of rolling bearings. The data sets are clustered by GMM to divide all data sets into several health states adaptively and reasonably. The number of clusters is determined by the minimum description length principle. Thus, either the health state of the data sets or the number of the states is obtained automatically. Meanwhile, the abnormal data sets can be recognized during the clustering process and removed from the training data sets. After obtaining the health states, appropriate features are selected by DET for increasing the classification and prediction accuracy. In the prediction process, each vibration signal is decomposed into several components by empirical mode decomposition. Some common statis- tical parameters of the components are calculated first and then the features are clustered using GMM to divide the data sets into several health states and remove the abnormal data sets. Thereafter, appropriate statistical parameters of the generated components are selected using DET. Finally, least squares support vector machine is utilized to predict the RUL of rolling *** results indicate that the proposed method reliably predicts the RUL of rolling bearings.

关键词： Gaussian mixture model distance evaluation technique health state remaining useful life rolling bearing

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Affine & Scale-Invariant Heterogeneous Pyramid Features for Automatic Matching of High Resolution Pushbroom Imagery from Chang'e 2 Satellite

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Journal of Earth Science 2016年第4期27卷 716-726页

作者： Sheng Yang Shibing Zhu Zhenju li xuejun li Tao liu Jue Wang Jianwei Xie Department of Information Equipment the Equipment Academy

The automatic feature extracting and matching for large amount of linear pushbroom imagery with higher and higher resolution is urgent and challenging in three dimensional reconstructions, remote sensing and mapping. Affine ＆ scale-invariant heterogeneous pyramid feature is proposed in this paper, along with the new scale-invariant analysis method, the detecting of the key points, the affine ＆ scale-invariant descriptor, the steering method of the matching, and the quasi-dense matching algorithm based on the extensive epipolar geometry. The automatic matching is devised for the linear pushbroom imagery. The whole process is executed on lunar images of the highest resolution of ~7 m/pixel（or ~1 m/pixel in the lower orbits） from the Chinese Chang＇e 2 satellite, it runs robustly at present, and resulting in large amounts of well-distributed-correspondences with accuracy of 0.3 pixels and excellent reliability, which gives great support for the further exploration both on the Moon and the Earth.

关键词： image matching linear pushbroom imagery epipolar geometry quasi-dense matching.

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