检索结果-南通市图书馆

Structure instability forecasting and analysis of giant rock pillars in steeply dipping thick coal seams

International Journal of Minerals,Metallurgy and Materials 2015年第12期22卷 1233-1244页

作者： Xing-ping Lai Huan Sun Peng-fei Shan Ming Cai jian-tao cao Feng Cui Energy School Xi’an University of Science and Technology Key Laboratory of Western Mines and Hazard Prevention (Ministry of Education of China) Bharti School of Engineering Laurentian University

Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams （SDTCS） are common in the Urumqi coalfield, and some dynamical hazards such as roof collapse and mining-induced seismicity occur frequently in the coal mines. The cause of these events is mainly structure instability in giant rock pillars sand- wiched between SDTCS. Developing methods to predict these events is important for safe mining in such a complex environment. This study focuses on understanding the structural mechanics model of a giant rock pillar and presents a viewpoint of the stability of a trend sphenoid fractured beam （TSFB）. Some stability index parameters such as failure surface dips were measured, and most dips were observed to be between 46° and 51°. We used a digital panoramic borehole monitoring system to measure the TSFB＇s height （△H）, which varied from 56.37 to 60.50 m. Next, FLAC^3D was used to model the distribution and evolution of vertical displacement in the giant rock pillars; the results confirmed the existence of a TSFB structure. Finally, we investigated the acoustic emission （AE） energy accumulation rate and observed that the rate commonly ranged from 20 to 40 kJ/min. The AE energy accumulation rate could be used to anticipate impeding seismic events related to structure failure. The results presented provide a useful approach for forecasting catastrophic events related to structure instability and for developing hazard prevention technology for mining in SDTCS.

关键词： coal mining structural instability rock pillars forecasting acoustic emission (AE) steeply dipping coal beds

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The renaissance of oxo synthesis: heterogeneous Rh-catalyzed hydroformylation

引用

Science China Chemistry 2025年

作者： tao Yan Zhi cao State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences National Energy Center for Coal to Clean Fuels Synfuels China Technology Co. Ltd.

Hydroformylation could convert olefins and syngas （mixture of H2and CO） into aldehydes with a great atomic *** transformation serves as one of the most prominent processes in modern chemical industry, as it provides over 10million tons of aldehydes as feedstock for our daily essential products such as plasticizers, paints, solvents, and pharmaceuticals. This process generally requires efficient yet robust catalyst to realize decent efficacy. Compared with metals such as Co, Ru, and Pd, rhodium （Rh）-based catalysts stand out due to its superior activity even under mild reaction conditions, and dominate over 70%of global hydroformylation processes.

关键词：

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

The Mechanism of Heating Rate on the Secondary Recrystallization Evolution in Grain Oriented Silicon Steel

引用

Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 275-282页

作者： GAO Qian LI Jun WANG Xianhui cao Laifu GONG jian LI Bo Central Iron and Steel Research Institute Group Beijing 100081China Shougang Zhixin Electromagnetic Material R&D(Beijing)Co. Ltd.Beijing 101300China Beijing Shougang Co. Ltd.Qian’an 064404China

Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were *** illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically *** effect of precipitate ripening on the Goss texture and magnetic property was *** indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate *** recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}oriented grains growing abnormally and a magnetic induction intensity of ***,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss ***,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 *** a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this *** heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties.

关键词： high temperature annealing heating rate secondary recrystallization grain oriented silicon steel

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Positive effect of Mo on mechanical properties of a Ni-42W-10Co-x Mo medium heavy alloy

引用

China Foundry 2025年

作者： Guo-xin cao jian-xin Dong Yong-sheng He He jiang Fang Hao Zhi-hua Nie Teng-fei Ma Bao-quan Fu School of Materials Science and Engineering University of Science and Technology Beijing Xi'an Superalloy Technology Co. Ltd. School of Materials Science and Engineering Beijing Institute of Technology Key Laboratory of Air-driven Equipment Technology of Zhejiang Province Quzhou University

In this study,a novel Ni-W-Co-Mo medium heavy alloy (MHA) was designed to improve its mechanical strength via Mo *** the Ni-42W-10Co-xM o alloy series,where x represents the weight percent of Mo and varies between 0,1,2,5,and 10,the microstructure transitions from a dendritic structure to a hypoeutectic structure as the Mo content increases from 0 to 5wt.%.Moreover,as the Mo content increases from 0to 10wt.%,the distribution of theμ-phase shifts from being individually dispersed to forming aggregates,and its volume fraction rises from 0.5%to 7.9%.Notably,theμ-phase evolves into an eutectic microstructure,which helps in minimizing the segregation of *** change is accompanied by a substantial enhancement in mechanical properties;specifically,the compressive yield strength at room temperature increases from 350 MPa to 646 MPa,indicating a significant 85%***,the microhardness increases from 230 HV to 304 *** dynamics simulations further reveal that the strengthening mechanism of Ni-42W-10Co-xM o alloys is Mo-induced solid solution strengthening and precipitation strengthening.

关键词：

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

PARAMETRIC IDENTIFICATION OF PARALLEL MANIPULATOR WITH REDUNDANCY DRIVEN BY PNEUMATIC MUSCLES

引用

Chinese Journal of Mechanical Engineering 2008年第1期21卷 66-71页

作者： ZHU Xiaocong tao Guoliang cao jian State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A new parameter estimation algorithm is proposed for parametric identification of a parallel manipulator driven by pneumatic muscles with redundancy. Due to the special physical properties of the parallel manipulator studied, the regression model for parametric identification is characterized by multieollinearity, which will result in unreliable and inaccurate parameter estimations with large eovarianee if the conventional parameter estimation algorithm based on single error minimizing criterion is used. To improve the quality of parameter estimation and achieve high precise posture trajectory tracking control of the parallel manipulator, a new parameter estimation algorithm based on composite error minimizing criterion is developed in need of theoretical contractive forces of pneumatic muscles. The experimental results indicate that the proposed algorithm integrated with adaptive robust control could provide reliable parametric identification and greatly enhance the control accuracy in the trajectory tracking control of the parallel manipulator, and that the variation of known theoretical contractive forces of pneumatic muscles has slight influence on the control performance.

关键词： Pneumatic muscle Parallel manipulator Redundancy Parameter estimation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Pressure observer based adaptive robust trajectory tracking control of a parallel manipulator driven by pneumatic muscles

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1928-1937页

作者： ZHU Xiao-cong tao Guo-liang cao jian The State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

This paper presents a pressure observer based adaptive robust controller (POARC) for posture trajectory tracking of a parallel manipulator driven by three pneumatic muscles without pressure sensors. Due to model errors of the static forces and friction forces of pneumatic muscles, simplified average flow rate characteristics of valves, unknown disturbances of entire system, and unmeasured pressures, there exist rather severe parametric uncertainties, nonlinear uncertainties and dynamic uncertainties in modeling of the parallel manipulator. A nonlinear pressure observer is constructed to estimate unknown pressures on the basis of a single-input-single-output (SISO) decoupling model that is simplified from the actual multiple-input-multiple-output (MIMO) coupling model of the parallel manipulator. Then, an adaptive robust controller integrated with the pressure observer is developed to accomplish high precision posture trajectory tracking of the parallel manipulator. The experimental results indicate that the system with the proposed POARC not only achieves good control accuracy and smooth movement but also maintains robustness to disturbances.

关键词： Pneumatic muscle Parallel manipulator Pressure observer Adaptive robust control Trajectory tracking

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Adaptive Robust Tracking Control of Pressure Trajectory Based on Kalman Filter

引用

Chinese Journal of Mechanical Engineering 2009年第3期22卷 433-439页

作者： cao jian ZHU Xiaocong tao Guoliang YAO Bin The State Key Lab of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China School of Mechanical Engineering Purdue University Lafayette IN 47907 USA

When adaptive robust control（ARC） strategy based on backstepping design is applied in pneumatic servo control, accurate pressure tracking in motion is especially necessary for both force and position trajectories tracking ofrodless pneumatic cylinders, and therefore an adaptive robust pressure controller is developed in this paper to improve the tracking accuracy of pressure trajectory in the chamber when the pneumatic cylinder is moving. In the proposed adaptive robust pressure controller, off-line fitting of the orifice area and on-line parameter estimation of the flow coefficient are utilized to have improved model compensation, and meanwhile robust feedback and Kalman filter are used to have strong robustness against uncertain nonlinearities, parameter fluctuations and noise. Research results demonstrate that the adaptive robust pressure controller could not only track various pressure trajectories accurately even when the pneumatic cylinder is moving, but also obtain very smooth control input, which indicates the effectiveness of adaptive model compensation. Especially when a step pressure trajectory is tracked under the condition of the movement of a rodless pneumatic cylinder, maximum tracking error of ARC is 4.46 kPa and average tracking error is 0.99 kPa, and steady-state error of ARC could achieve 0.84 kPa, which is very close to the measurement accuracy of pressure transducer.

关键词： pneumatic servo control adaptive robust control Kalman filter orifice area

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

MODELING AND CONTROLLING OF PARALLEL MANIPULATOR JOINT DRIVEN BY PNEUMATIC MUSCLES

引用

Chinese Journal of Mechanical Engineering 2005年第4期18卷 537-541页

作者： tao Guoliang Zhu Xiaocong cao jian State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A parallel manipulator joint driven by three pneumatic muscles and its posture control strategy are presented. Based on geometric constraints and dynamics, a system model is developed through which some influences on dynamic response and open-loop gain are analyzed including the supply pressure, the initial pressure and the volume of pneumatic muscle. A sliding-mode controller with a nonlinear switching function is applied to control posture, which adopts the combination of a main method that separates control of each muscle and an auxiliary method that postures error evaluation of multiple muscles, especially adopting the segmented and intelligent adjustments of sliding-mode parameters to fit different expected postures and initial states. Experimental results show that this control strategy not only amounts to the steady-state error of 0. 1° without overshoot, but also achieves good trajectory tracking.

关键词： Pneumatic muscle Parallel manipulator joint Sliding-mode controller Posture control

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于消费者介入理论的在线购买行为影响要素及预测研究

引用

管理工程学报 2025年第2期39卷 144-161页

作者：陶婉琼王子卓王健浙江工商大学统计数据工程技术与应用协同创新中心浙江杭州310018 浙江大学管理学院浙江杭州310030 浙江吉利控股集团有限公司浙江杭州310051 浙江工商大学管理工程与电子商务学院杭州310018 浙江工商大学现代商贸研究中心杭州310018

本文主要研究消费者在线购买行为的影响。本文首先从参与强度、消费者类型、购物流程类型和广告点击次数四个维度定义了表征消费者在线购买决策心理特征的消费者介入水平,然后基于消费者介入理论分别从群体水平和个体水平的视角分析消... 详细信息

本文主要研究消费者在线购买行为的影响。本文首先从参与强度、消费者类型、购物流程类型和广告点击次数四个维度定义了表征消费者在线购买决策心理特征的消费者介入水平,然后基于消费者介入理论分别从群体水平和个体水平的视角分析消费者介入水平维度对其购物数量和购物时间间隔等行为的影响。以此为基础,本文采用多种机器学习方法构建了消费者在线购买行为预测模型。通过对不同预测模型的比较发现,神经网络回归模型对购物数量预测的误差性最小和拟合度最高,而梯度提升回归模型对购物时间间隔预测的性能最好。同时,通过特征变量的重组设置对比实验,本文验证了在购买行为预测模型中引入介入水平维度的有效性和合理性。研究结果揭示了消费者介入水平对在线购买行为的影响规律,不仅丰富了相关理论,而且对网购平台和商家精确预测消费者购买行为、优化服务策略等方面具有重要的指导意义。

关键词：决策科学电子商务消费者介入在线购买行为预测模型

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Electrical Derivative Measurement of High-Power InGaAs LDs Under Scanning Current with Variable Step

引用

Chinese Journal of Electronics 2017年第3期26卷 508-513页

作者： tao Min GUAN jian GAO Fengli GAO Liangli cao Junsheng State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University The 27th Research Institute China Electronics Technology Group Corporation Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences

For the large driving current of high-power semiconductor Laser diodes(LDs),a modified method to measure the electrical derivative of LDs under scanning driving current with variable step length is proposed,which is to achieve the fast and accurate measurement of optical and electrical characteristic parameters of LDs with a relatively small data *** experimental results show that,with fewer measurements,this method can effectively and accurately measure and extract the LDs corresponding parameters including threshold current(Ith),voltage-current characteristic(V-I),luminous power-current relation(P-I),electrical derivative curve(Id V/d I-I).The wavelet transformation singularity testing results of the threshold current also verify the accuracy,reliability,and advantage of this method.

关键词： Semiconductor laser diodes(LDs) Electrical derivative Scanning current Wavelet transform Singularity detection

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：