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Research on the dynamic response of connecting rod bearing bush wear of reciprocating machine under variable working conditions
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作者 张进杰 SONG Chunyu +3 位作者 LEI Fuchang WANG Yao ZHI Haifeng LIU Fengchun 《High Technology Letters》 EI CAS 2023年第2期148-158,共11页
As a type of reciprocating machine, the reciprocating compressor has a compact structure and many excitation sources.Once the small end bearing of the connecting rod is worn, it is easy to cause the sintering of the b... As a type of reciprocating machine, the reciprocating compressor has a compact structure and many excitation sources.Once the small end bearing of the connecting rod is worn, it is easy to cause the sintering of the bearing and the abnormal vibration of the body.Based on the characteristics of poor lubrication state and complex force of connecting rod small head bearing, a mixed lubrication model considering oil groove feed was established, and the dynamic simulation of the reciprocating compressor model with lubricated bearings was carried out;considering different speeds and gas load conditions, the law of the impact of the eigenvalues changing with working conditions was explored.The fault simulation experiment was carried out by selecting representative working conditions, which verified the correctness of the simulation method.The study found that two contact collisions between the pin and the bearing bush occurred in one cycle, the collision impact was more severe under the wear fault, and the existence of the gap made the dynamic response more sensitive to the change of working conditions.This research provides ideas for the location and feature extraction of fault symptom signal angular segments in the process of complex measured signal processing. 展开更多
关键词 small head tile WEAR LUBRICATION variable working condition impact
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GLOBAL CONVERGENCE OF A CLASS OF OPTIMALLY CONDITIONED SSVM METHODS
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作者 杨正方 夏爱生 +1 位作者 韩立兴 刘光辉 《Transactions of Tianjin University》 EI CAS 1997年第1期73-76,共4页
This paper explores the convergence of a class of optimally conditioned self scaling variable metric (OCSSVM) methods for unconstrained optimization. We show that this class of methods with Wolfe line search are glob... This paper explores the convergence of a class of optimally conditioned self scaling variable metric (OCSSVM) methods for unconstrained optimization. We show that this class of methods with Wolfe line search are globally convergent for general convex functions. 展开更多
关键词 optimally conditioned self scaling variable metric methods global convergence unconstrained optimization
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Feature Extraction Method Based on Pseudo-Wigner-Ville Distribution for Rotational Machinery in Variable Operating Conditions 被引量:8
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作者 WANG Huaqing LIKe +1 位作者 SUN Hao CHEN Peng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2011年第4期661-668,共8页
In the case of fault diagnosis for roller bearings, the conventional diagnosis approaches by using the time interval of energy impacts in time-frequency distribution or the pass-frequencies are based on the assumption... In the case of fault diagnosis for roller bearings, the conventional diagnosis approaches by using the time interval of energy impacts in time-frequency distribution or the pass-frequencies are based on the assumption that machinery operates under a constant rotational speed. However, when the rotational speed varies in the broader range, the pass-frequencies vary with the change of rotational speed and bearing faults cannot be identified by the interval of impacts. Researches related to automatic diagnosis for rotational machinery in variable operating conditions were quite few. A novel automatic feature extraction method is proposed based on a pseudo-Wigner-Ville distribution (PWVD) and an extraction of symptom parameter (SP). An extraction method for instantaneous feature spectrum is presented using the relative crossing information (RCI) and sequential inference approach, by which the feature spectrum from time-frequency distribution can be automatically, sequentially extracted. The SPs are considered in the frequency domain using the extracted feature spectrum to identify among the conditions of a machine. A method to obtain the synthetic symptom parameter is also proposed by the least squares mapping (LSM) technique for increasing the diagnosis sensitivity of SP. Practical examples of diagnosis for bearings are given in order to verify the effectiveness of the proposed method. The verification results show that the features of bearing faults, such as the outer-race, inner-race and roller element defects have been effectively extracted, and the proposed method can be used for condition diagnosis of a machine under the variable rotational speed. 展开更多
关键词 feature extraction pseudo-wigner-ville distribution variable operating condition sequential diagnosis
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Establishment of Dynamic Model for Axle Box Bearing of High-Speed Trains Under Variable Speed Conditions 被引量:5
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作者 Yongqiang Liu Baosen Wang +1 位作者 Bin Zhang Shaopu Yang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第4期340-351,共12页
In this study,a dynamic model for the bearing rotor system of a high-speed train under variable speed conditions is established.In contrast to previous studies,the contact stress is simplifed in the proposed model and... In this study,a dynamic model for the bearing rotor system of a high-speed train under variable speed conditions is established.In contrast to previous studies,the contact stress is simplifed in the proposed model and the compensation balance excitation caused by the rotor mass eccentricity considered.The angle iteration method is used to overcome the challenge posed by the inability to determine the roller space position during bearing rotation.The simulation results show that the model accurately describes the dynamics of bearings under varying speed profles that contain acceleration,deceleration,and speed oscillation stages.The order ratio spectrum of the bearing vibration signal indicates that both the single and multiple frequencies in the simulation results are consistent with the theoretical results.Experiments on bearings with outer and inner ring faults under various operating conditions are performed to verify the developed model. 展开更多
关键词 Variable speed conditions High-speed train Bearing model Angle iteration Order ratio spectrum
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Numerical Simulation of Axial Inflow Characteristics and Aerodynamic Noise in a Large-Scale Adjustable-Blade Fan 被引量:4
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作者 Lin Wang Chunguo An +4 位作者 Nini Wang Yaming Ping Kun Wang Ming Gao Suoying He 《Fluid Dynamics & Materials Processing》 EI 2020年第3期585-600,共16页
Numerical simulation are conducted to explore the characteristics of the axial inflow and related aerodynamic noise for a large-scale adjustable fan with the installation angle changing from−12°to 12°.In suc... Numerical simulation are conducted to explore the characteristics of the axial inflow and related aerodynamic noise for a large-scale adjustable fan with the installation angle changing from−12°to 12°.In such a range the maximum static(gauge)pressure at the inlet changes from−2280 Pa to 382 Pa,and the minimum static pressure decreases from−3389 Pa to−8000 Pa.As for the axial intermediate flow surface,one low pressure zone is located at the junction of the suction surface and the hub,another is located at the suction surface close to the casing position.At the outlet boundary,the low pressure is negative and decreases from−1716 Pa to−4589 Pa.The sound pressure level of the inlet and outlet noise tends to increase monotonously by 11.6 dB and 7.3 dB,respectively.The acoustic energy of discrete noise is always higher than that of broadband noise regardless of whether the inlet or outlet flow surfaces are considered.The acoustic energy ratio of discrete noise at the inlet tends to increase from 0.78 to 0.93,while at the outlet it first decreases from 0.79 to 0.73 and then increases to 0.84. 展开更多
关键词 Adjustable blade axial flow fan variable installation angle condition axial static pressure aerodynamic noise
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Health status assessment of axial piston pump under variable speed 被引量:1
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作者 Guo Rui Li Hucheng +3 位作者 Zhao Zhiqian Zhang Rongbing Zhao Jingyi Gao Dianrong 《High Technology Letters》 EI CAS 2020年第3期315-322,共8页
The axial piston pump usually works under variable speed conditions.It is important to evaluate the health status of the axial piston pump under the variable speed condition.Aiming at the characteristic signals obtain... The axial piston pump usually works under variable speed conditions.It is important to evaluate the health status of the axial piston pump under the variable speed condition.Aiming at the characteristic signals obtained under different wear levels of the port plate,a feature signal extraction method under variable speed conditions is proposed.Firstly,the combination of complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)energy spectrum and fast spectral kurtosis principle is used to accurately extract the intrinsic mode function(IMF)component containing the sensitive information of the degraded feature.Then,the aspect ratio analysis method of the angle domain variational mode decomposition(VMD)is used to process the feature index containing the sensitive information of the degraded feature.In order to evaluate the health status of the axial piston pump under variable speed,the vibration reliability analysis method for axial piston pump based on Weibull proportional failure rate model is proposed.The experimental results show that the proposed method can accurately evaluate the health status of the axial piston pump. 展开更多
关键词 axial piston pump variable speed condition order ratio variational mode decomposition(VMD)in angle domain health status assessment
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Feasibility Analysis of Back-Pressure Steam Feeding Water Pump for Direct Air-Cooled Unit 被引量:1
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作者 Zhao Xiaodong Wang Meng +2 位作者 Du Xiaoze Yang Lijun Yang Yongping 《Electricity》 2013年第1期31-35,共5页
As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introd... As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified. 展开更多
关键词 air-cooled back-pressure steam turbine steam feed water pump variable condition
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Component modeling and updating method of integrated energy systems based on knowledge distillation
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作者 Xueru Lin Wei Zhong +4 位作者 Xiaojie Lin Yi Zhou Long Jiang Liuliu Du-Ikonen Long Huang 《Energy and AI》 EI 2024年第2期184-199,共16页
Amid the backdrop of carbon neutrality, traditional energy production is transitioning towards integrated energy systems (IES), where model-based scheduling is key in scenarios with multiple uncertainties on both supp... Amid the backdrop of carbon neutrality, traditional energy production is transitioning towards integrated energy systems (IES), where model-based scheduling is key in scenarios with multiple uncertainties on both supply and demand sides. The development of artificial intelligence algorithms, has resolved issues related to model accuracy. However, under conditions of high proportion renewable energy integration, component load adjustments require increased flexibility, so the mathematical model of the component must adapt to constantly changing operating conditions. Therefore, the identification of operating condition changes and rapid model updating are pressing issues. This study proposes a modeling and updating method for IES components based on knowledge distillation. The core of this modeling method is the light weighting of the model, which is achieved through a knowledge distillation method, using a teacher-student mode to compress complex neural network models. The triggering of model updates is achieved through principal component analysis. The study also analyzes the impact of model errors caused by delayed model updates on the overall scheduling of IES. Case studies are conducted on critical components in IES, including coal-fired boilers and turbines. The results show that the time consumption for model updating is reduced by 76.67 % using the proposed method. Under changing conditions, compared with two traditional models, the average deviation of this method is reduced by 12.61 % and 3.49 %, respectively, thereby improving the model's adaptability. The necessity of updating the component model is further analyzed, as a 1.00 % mean squared error in the component model may lead to a power deviation of 0.075 MW. This method provides real-time, adaptable support for IES data modeling and updates. 展开更多
关键词 Component modeling Adaptive update Knowledge distillation Variable operating conditions Integrated energy system DATA-DRIVEN
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Application of Transfer Learningin Mechanical Equipment Intelligent Diagnosis:Literature Review
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作者 LIU Tao WANG Zhenya +1 位作者 WU Xing LI Menghang 《昆明理工大学学报(自然科学版)》 北大核心 2024年第4期154-169,共16页
Accelerating the process of intelligent manufacturing and the demand for new industrial productivity,the operating conditions of machinery and equipment have become ever more severe.As an important link to ensure the ... Accelerating the process of intelligent manufacturing and the demand for new industrial productivity,the operating conditions of machinery and equipment have become ever more severe.As an important link to ensure the stable operation of the production process,the condition monitoring and fault diagnosis of equipment have become equally important.The fault diagnosis of equipment in actual production is often challenged by variable working conditions,large differences in data distribution,and lack of labeled samples,etc.Traditional fault diagnosis methods are often difficult to achieve ideal results in these complex environments.Transfer learning(TL)as an emerging technology can effectively utilize existing knowledge and data to improve the diagnostic performance.Firstly,this paper analyzes the trend of mechanical equipment fault diagnosis and explains the basic concept of TL.Then TL based on parameters,TL based on features,TL based on instances and domain adaptive(DA)methods are summarized and analyzed in terms of existing TL methods.Finally,the problems faced in the current TL research are summarized and the future development trend is pointed out.This review aims to help researchers in related fields understand the latest progress of TL and promote the application and development of TL in mechanical equipment diagnosis. 展开更多
关键词 mechanical equipment transfer learning variable operating conditions fault diagnosis sample distribution differences
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Conditional mean convergence theorems of conditionally dependent random variables under conditions of integrability
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作者 Xinghui WANG Shuhe HU 《Frontiers of Mathematics in China》 SCIE CSCD 2015年第3期681-696,共16页
We give the conditionally residual h-integrability with exponent r for an array of random variables and establish the conditional mean convergence of conditionally negatively quadrant dependent and conditionally negat... We give the conditionally residual h-integrability with exponent r for an array of random variables and establish the conditional mean convergence of conditionally negatively quadrant dependent and conditionally negative associated random variables under this integrability. These results generalize and improve the known ones. 展开更多
关键词 Conditional negatively quadrant dependent (NQD) random variable conditional negatively associated (NA) random variable conditional mean convergence conditionally residual h-integrability
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Automatic Efficiency Optimization of an Axial Compressor with Adjustable Inlet Guide Vanes 被引量:1
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作者 Jichao Li Feng Lin +1 位作者 Chaoqun Nie Jingyi Chen 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第2期120-126,共7页
The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the eff... The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the efficiency, the DSP (Digital Signal Processor) controller is designed to adjust the stagger angle of IGV automatically in order to optimize the efficiency at any operating condition. The A/D signal collection includes inlet static pressure, outlet static pressure, outlet total pressure, rotor speed and torque signal, the efficiency can be calculated in the DSP, and the angle signal for the stepping motor which control the IGV will be sent out from the D/A. Experimental investigations are performed in a three-stage, low-speed axial compressor with variable inlet guide vanes. It is demonstrated that the DSP designed can well adjust the stagger angle of IGV online, the efficiency under different conditions can be optimized. This establishment of DSP online adjustment scheme may provide a practical solution for improving performance of multi-stage axial flow compressor when its operating condition is varied. 展开更多
关键词 DSP Inlet guide vane EFFICIENCY Axial compressor Variable condition Control algorithm
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Development and stability analysis of a high-speed train bearing system under variable speed conditions 被引量:2
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作者 Baosen Wang Yongqiang Liu +1 位作者 Bin Zhang Shaopu Yang 《International Journal of Mechanical System Dynamics》 2022年第4期352-362,共11页
During a high-speed train operation,the train speed changes frequently,resulting in motion change as a function of time.A dynamic model of a double‐row tapered roller bearing system of a high-speed train under variab... During a high-speed train operation,the train speed changes frequently,resulting in motion change as a function of time.A dynamic model of a double‐row tapered roller bearing system of a high-speed train under variable speed conditions is developed.The model takes into consideration the structural characteristics of one outer ring and two inner rings of the train bearing.The angle iteration method is used to determine the rotation angle of the roller within any time period,solving the difficult problem of determining the location of the roller.The outer ring and inner ring faults are captured by the model,and the model response is obtained under variable speed conditions.Experiments are carried out under two fault conditions to validate the model results.The simulation results are found to be in good agreement with the results of the formula,and the errors between the simulation results and the experimental results when the bearing has outer and inner ring faults are found to be,respectively,5.97% and 2.59%,which demonstrates the effectiveness of the model.The influence of outer ring and inner ring faults on system stability is analyzed quantitatively using the Lempel–Ziv complexity.The results show that for low train acceleration,the inner ring fault has a more significant effect on the system stability,while for high acceleration,the outer ring fault has a more significant effect.However,when the train acceleration changes,the outer ring has a greater influence.In practice,train acceleration is usually small and does not frequently change in one operation cycle.Therefore,the inner ring fault of the bearing deserves more attention. 展开更多
关键词 high-speed train bearing model variable speed conditions stability analysis Lempel-Ziv complexity
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