To address the issue of abnormal energy consumption fluctuations in the converter steelmaking process,an integrated diagnostic method combining the gray wolf optimization(GWO)algorithm,support vector machine(SVM),and ...To address the issue of abnormal energy consumption fluctuations in the converter steelmaking process,an integrated diagnostic method combining the gray wolf optimization(GWO)algorithm,support vector machine(SVM),and K-means clustering was proposed.Eight input parameters—derived from molten iron conditions and external factors—were selected as feature variables.A GWO-SVM model was developed to accurately predict the energy consumption of individual heats.Based on the prediction results,the mean absolute percentage error and maximum relative error of the test set were employed as criteria to identify heats with abnormal energy usage.For these heats,the K-means clustering algorithm was used to determine benchmark values of influencing factors from similar steel grades,enabling root-cause diagnosis of excessive energy consumption.The proposed method was applied to real production data from a converter in a steel plant.The analysis reveals that heat sample No.44 exhibits abnormal energy consumption,due to gas recovery being 1430.28 kg of standard coal below the benchmark level.A secondary contributing factor is a steam recovery shortfall of 237.99 kg of standard coal.This integrated approach offers a scientifically grounded tool for energy management in converter operations and provides valuable guidance for optimizing process parameters and enhancing energy efficiency.展开更多
The Renin-Angiotensin System(RAS)plays an important role in post-surgical adhesion formation.Angiotensin-Ⅱ is synthesized in uterus and plays an important role in intraorganic connective tissue proteins metabolism an...The Renin-Angiotensin System(RAS)plays an important role in post-surgical adhesion formation.Angiotensin-Ⅱ is synthesized in uterus and plays an important role in intraorganic connective tissue proteins metabolism and blood vessels regeneration.The studies found that longterm introduction of ACE blockers(captopril)to rats that undergwent single talc intraperitoneal injection with the aim of stimulation of adhesion formation,promotes development of inflammation and fibrosis in the uterus and activation of the adhesion formation.Stimulation of posttraumatic adhesions in female rats treated with an ACE is accompanied by inhibition of neoangiogenesis in the injured tissues.展开更多
不同于传统光伏(PV)系统中应用的DC-DC变换器,差值功率处理(differential power processing,DPP)变换器可以在功率损失较小、能量转换效率较高的情况下,实现光伏系统的最大功率输出。为确保基于DPP拓扑光伏系统的供电连续性和可靠性,文...不同于传统光伏(PV)系统中应用的DC-DC变换器,差值功率处理(differential power processing,DPP)变换器可以在功率损失较小、能量转换效率较高的情况下,实现光伏系统的最大功率输出。为确保基于DPP拓扑光伏系统的供电连续性和可靠性,文章针对光伏系统中DPP变换器最易出现故障的功率开关器件提出了一种快速故障诊断方法。所提方法通过检测DPP变换器不同开关状态下电感电流的变化斜率符号和幅值来进行故障的快速诊断,与其他故障诊断方法相比,此方法只需增加少量的传感器件,具有诊断速度更快,且不改变原有的系统结构等优点。最后通过仿真验证了该故障诊断方法的快速性和有效性。展开更多
Online monitoring and diagnosis of production processes face great challenges due to the nonlinearity and multivariate of complex industrial processes.Traditional process monitoring methods employ kernel function or m...Online monitoring and diagnosis of production processes face great challenges due to the nonlinearity and multivariate of complex industrial processes.Traditional process monitoring methods employ kernel function or multilayer neural networks to solve the nonlinear mapping problem of data.However,the above methods increase the model complexity and are not interpretable,leading to difficulties in subsequent fault recognition/diagnosis/location.A process monitoring and diagnosis method based on the free energy of Gaussian-Bernoulli restricted Boltzmann machine(GBRBM-FE)was proposed.Firstly,a GBRBM network was established to make the probability distribution of the reconstructed data as close as possible to the probability distribution of the raw data.On this basis,the weights and biases in GBRBM network were used to construct F statistics,which represents the free energy of the sample.The smaller the energy of the sample is,the more normal the sample is.Therefore,F statistics can be used to monitor the production process.To diagnose fault variables,the F statistic for each sample was decomposed to obtain the Fv statistic for each variable.By analyzing the deviation degree between the corresponding variables of abnormal samples and normal samples,the cause of process abnormalities can be accurately located.The application of converter steelmaking process demonstrates that the proposed method outperforms the traditional methods,in terms of fault monitoring and diagnosis performance.展开更多
This letter studies and analyzes the working features of main circuit of tri-level boost Power Factor Correct(PFC) converter and the advantages of tri-level switch converter in aspects of bearing high-voltage of power...This letter studies and analyzes the working features of main circuit of tri-level boost Power Factor Correct(PFC) converter and the advantages of tri-level switch converter in aspects of bearing high-voltage of power components,overall system loss and magnetic component selection based upon the single-level boost PFC switch converter.Besides,relying on the application of mi-croprocessor in power converter technology and DSP(Digital Signal Processing) chip's strong cal-culating capacity,the letter presents the adoption of modified scheme of tri-level boost PFC converter under the control of predictive control algorithm.Moreover,the operating principle and control method are specified,the results of circuit test and analysis are provided and the advantages of pre-dictive control technology-based multi-level boost PFC converter is verified.展开更多
By considering the failure of normal distribution and continuous assumption in financial modeling, this paper attempts to apply the Exponential Variance Gamma （EVG） model into the pricing framework of permanent conv...By considering the failure of normal distribution and continuous assumption in financial modeling, this paper attempts to apply the Exponential Variance Gamma （EVG） model into the pricing framework of permanent convertible bonds with call clause. Following framework of Gapeev ＆ Kiihn（2005）, we obtain an explicit solution to the bond price and optimal stopping strategies, which shows that the new pricing framework is quite different from the continuous model and even the Jump Diffusion model. Compared with the numerical calculation, the closed form results price convertible bonds quickly and accurately.展开更多
The effects of contact surface on dynamic wedging behavior of the roller and inner-ring of the overrunning clutch in a dual-turbine torque converter were investigated to reveal the friction self- locking mechanism and...The effects of contact surface on dynamic wedging behavior of the roller and inner-ring of the overrunning clutch in a dual-turbine torque converter were investigated to reveal the friction self- locking mechanism and dynamic process. Planar strain clutch models including roller, inner-ring and outer-ring were built, and transient wedging process was analyzed with an explicit dynamics meth- od. The modeling of stress and strain distribution and variation of two kinds of contact surfaces show that there are three stages named slipping, wedging and binding respectively during whole wed- ging process. Meanwhile the geometric structures of contact surfaces greatly influence the peak stress and strain distribution of the wedging process of the roller and inner-ring. The load bearing performance of contact surfaces with logarithmic spiral curve is better than that with straight line. Our study provides theoretical foundation for design and further optimization of wedging contact surface of an overrunning clutch in a dual-turbine hydrodynamic torque converter.展开更多
在中小型永磁同步风力发电机中,桥式整流+DC/DC变换器拓扑具有结构简单的优点,其中DC/DC电路有Boost和Buck两种拓扑,探究两者的最大功率点跟踪(Maximum Power Point Tracking,MPPT)控制性能区别是对其优化设计的关键,测控系统是性能分...在中小型永磁同步风力发电机中,桥式整流+DC/DC变换器拓扑具有结构简单的优点,其中DC/DC电路有Boost和Buck两种拓扑,探究两者的最大功率点跟踪(Maximum Power Point Tracking,MPPT)控制性能区别是对其优化设计的关键,测控系统是性能分析的重要手段。通过系统总体方案设计,确认了系统参数及指标;分析了四桥臂DC/DC拓扑,并基于高端电流采样和隔离采样技术实现了系统电压、电流、功率和频率的采集,设计了功率驱动及单片机控制电路;探讨了适合单片机的MPPT爬坡搜索法软件;给出了基于LabVIEW的上位机操控系统的软件设计实现;搭建了测控系统,进行了MPPT和两种拓扑测控结果对比实验。实验结果表明测控系统达到了设计目标。展开更多
基金support from the National Key R&D Program of China(Grant No.2020YFB1711100).
文摘To address the issue of abnormal energy consumption fluctuations in the converter steelmaking process,an integrated diagnostic method combining the gray wolf optimization(GWO)algorithm,support vector machine(SVM),and K-means clustering was proposed.Eight input parameters—derived from molten iron conditions and external factors—were selected as feature variables.A GWO-SVM model was developed to accurately predict the energy consumption of individual heats.Based on the prediction results,the mean absolute percentage error and maximum relative error of the test set were employed as criteria to identify heats with abnormal energy usage.For these heats,the K-means clustering algorithm was used to determine benchmark values of influencing factors from similar steel grades,enabling root-cause diagnosis of excessive energy consumption.The proposed method was applied to real production data from a converter in a steel plant.The analysis reveals that heat sample No.44 exhibits abnormal energy consumption,due to gas recovery being 1430.28 kg of standard coal below the benchmark level.A secondary contributing factor is a steam recovery shortfall of 237.99 kg of standard coal.This integrated approach offers a scientifically grounded tool for energy management in converter operations and provides valuable guidance for optimizing process parameters and enhancing energy efficiency.
文摘The Renin-Angiotensin System(RAS)plays an important role in post-surgical adhesion formation.Angiotensin-Ⅱ is synthesized in uterus and plays an important role in intraorganic connective tissue proteins metabolism and blood vessels regeneration.The studies found that longterm introduction of ACE blockers(captopril)to rats that undergwent single talc intraperitoneal injection with the aim of stimulation of adhesion formation,promotes development of inflammation and fibrosis in the uterus and activation of the adhesion formation.Stimulation of posttraumatic adhesions in female rats treated with an ACE is accompanied by inhibition of neoangiogenesis in the injured tissues.
文摘不同于传统光伏(PV)系统中应用的DC-DC变换器,差值功率处理(differential power processing,DPP)变换器可以在功率损失较小、能量转换效率较高的情况下,实现光伏系统的最大功率输出。为确保基于DPP拓扑光伏系统的供电连续性和可靠性,文章针对光伏系统中DPP变换器最易出现故障的功率开关器件提出了一种快速故障诊断方法。所提方法通过检测DPP变换器不同开关状态下电感电流的变化斜率符号和幅值来进行故障的快速诊断,与其他故障诊断方法相比,此方法只需增加少量的传感器件,具有诊断速度更快,且不改变原有的系统结构等优点。最后通过仿真验证了该故障诊断方法的快速性和有效性。
基金the financial support from the National Key R&D Program of China(Grant No.2020YFA0405700).
文摘Online monitoring and diagnosis of production processes face great challenges due to the nonlinearity and multivariate of complex industrial processes.Traditional process monitoring methods employ kernel function or multilayer neural networks to solve the nonlinear mapping problem of data.However,the above methods increase the model complexity and are not interpretable,leading to difficulties in subsequent fault recognition/diagnosis/location.A process monitoring and diagnosis method based on the free energy of Gaussian-Bernoulli restricted Boltzmann machine(GBRBM-FE)was proposed.Firstly,a GBRBM network was established to make the probability distribution of the reconstructed data as close as possible to the probability distribution of the raw data.On this basis,the weights and biases in GBRBM network were used to construct F statistics,which represents the free energy of the sample.The smaller the energy of the sample is,the more normal the sample is.Therefore,F statistics can be used to monitor the production process.To diagnose fault variables,the F statistic for each sample was decomposed to obtain the Fv statistic for each variable.By analyzing the deviation degree between the corresponding variables of abnormal samples and normal samples,the cause of process abnormalities can be accurately located.The application of converter steelmaking process demonstrates that the proposed method outperforms the traditional methods,in terms of fault monitoring and diagnosis performance.
文摘This letter studies and analyzes the working features of main circuit of tri-level boost Power Factor Correct(PFC) converter and the advantages of tri-level switch converter in aspects of bearing high-voltage of power components,overall system loss and magnetic component selection based upon the single-level boost PFC switch converter.Besides,relying on the application of mi-croprocessor in power converter technology and DSP(Digital Signal Processing) chip's strong cal-culating capacity,the letter presents the adoption of modified scheme of tri-level boost PFC converter under the control of predictive control algorithm.Moreover,the operating principle and control method are specified,the results of circuit test and analysis are provided and the advantages of pre-dictive control technology-based multi-level boost PFC converter is verified.
基金Supported by the Key Grant Project of Chinese Ministry of Education (309018)National Natural Science Foundation of China (70973140, 11171304)Zhejiang Provincial Natural Science Foundation of China(Y6110023)
文摘By considering the failure of normal distribution and continuous assumption in financial modeling, this paper attempts to apply the Exponential Variance Gamma （EVG） model into the pricing framework of permanent convertible bonds with call clause. Following framework of Gapeev ＆ Kiihn（2005）, we obtain an explicit solution to the bond price and optimal stopping strategies, which shows that the new pricing framework is quite different from the continuous model and even the Jump Diffusion model. Compared with the numerical calculation, the closed form results price convertible bonds quickly and accurately.
基金Supported by the National Natural Science Foundation of China(51475041)the Ministerial Level Advanced Research Foundation(40402060103)the Ministerial Basic Products Innovation Program(VTDP2104)
文摘The effects of contact surface on dynamic wedging behavior of the roller and inner-ring of the overrunning clutch in a dual-turbine torque converter were investigated to reveal the friction self- locking mechanism and dynamic process. Planar strain clutch models including roller, inner-ring and outer-ring were built, and transient wedging process was analyzed with an explicit dynamics meth- od. The modeling of stress and strain distribution and variation of two kinds of contact surfaces show that there are three stages named slipping, wedging and binding respectively during whole wed- ging process. Meanwhile the geometric structures of contact surfaces greatly influence the peak stress and strain distribution of the wedging process of the roller and inner-ring. The load bearing performance of contact surfaces with logarithmic spiral curve is better than that with straight line. Our study provides theoretical foundation for design and further optimization of wedging contact surface of an overrunning clutch in a dual-turbine hydrodynamic torque converter.
文摘在中小型永磁同步风力发电机中,桥式整流+DC/DC变换器拓扑具有结构简单的优点,其中DC/DC电路有Boost和Buck两种拓扑,探究两者的最大功率点跟踪(Maximum Power Point Tracking,MPPT)控制性能区别是对其优化设计的关键,测控系统是性能分析的重要手段。通过系统总体方案设计,确认了系统参数及指标;分析了四桥臂DC/DC拓扑,并基于高端电流采样和隔离采样技术实现了系统电压、电流、功率和频率的采集,设计了功率驱动及单片机控制电路;探讨了适合单片机的MPPT爬坡搜索法软件;给出了基于LabVIEW的上位机操控系统的软件设计实现;搭建了测控系统,进行了MPPT和两种拓扑测控结果对比实验。实验结果表明测控系统达到了设计目标。
