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Research on active disturbance rejection control method for turbine blade tip clearance

Science China(Technological Sciences) 2019年第10期62卷 1795-1804页

作者： WANG WeiMin SHAO Xing li qihang Gao JinJi HAO ZeRui Beijing Key Laboratory of Health Monitoring and Self-Recovery for High-End Mechanical Equipment Beijing University of ChemicalTechnologyBeijing100029China Department of Mechanical Engineering Tsinghua UniversityBeijing100084China

Blade tip clearance(BTC) is one of the key factors affecting the efficiency and reliability of high performance turbomachinery such as heavy duty steam turbines, aircraft engines and other gas turbo machines. The self-adjusting ability of BTC according to the operation condition changing is important to meet the requirement of performance. In this paper, the principle and method of adjusting the BTC by controlling the axial displacement of the rotor were proposed and studied. The basic principle is that the BTC of the turbomachinery with a conical tail shroud will be affected by the axial displacement of rotor and thereby can be adjusted by controlling the axial position of rotor, which can be adjusted by the controllable oil pressure acting on the thrust bearing. To reach a higher control precision, lower noise and model perturbation, an adaptive quasi-sliding mode control(AQSMC) algorithm based on the disturbance observer(DOB) was designed, and numerical and experimental investigations were carried out. The numerical simulation results show that this algorithm can not only effectively suppress the disturbance, but also, compared with the general reaching law, effectively reduce the chattering and transient high gain switching effect of the closed-loop controller system and avoid the instability caused by the controller. Based on the DOB-AQSMC algorithm, the BTC was stabilized within 2 s with no overshoot and no misalignment in the test rig, and this algorithm achieves a better control performance than the proportion-integral-differential(PID) algorithm. These achievements can be used to push forward the intelligent turbomachinery development.

关键词： blade tip clearance turbomachinery active disturbance rejection control DOB-AQSM method

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Experimental study on instability mechanism and critical intensity of rainfall of high-steep rock slopes under unsaturated conditions

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International Journal of Mining Science and Technology 2023年第10期33卷 1243-1260页

作者： Xiaoshuang li qihang li Yunmin Wang Wei liu Di Hou Wenbo Zheng Xiong Zhang School of Urban Construction Changzhou UniversityChangzhou 213164China College of Civil Engineering Qilu Institute of TechnologyJinan 250200China Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province Shaoxing 312000China School of Resources and Safety Engineering Chongqing UniversityChongqing 400044China Sinosteel Maanshan General Institute of Mining Research Co.LTD. Maanshan 243000China Guizhou Survey and Design Research Institute for Water Resources and Hydropower Guiyang 550001China School of Engineering University of Northern British ColumbiaPrince George V2K3V3Canada

Two critical factors,namely intense precipitation and intricate excavation,can trigger rock mass disasters in mining *** this study,an indoor rainfall system was developed to precisely regulate the flow and intensity of precipitation.A large-scale model experiment was conducted on a self-designed physical simulation experiment platform to investigate the failure and instability of high-steep rock slopes under unsaturated *** real-time reproduction of the progressive failure process in high-steep rock slopes enabled the determination of the critical rainfall intensity and revealed the mechanism underlying slope *** results indicated that rainfall may be the primary factor contributing to rock mass instability,while continuous pillar mining exacerbates the extent of rock mass *** critical failure stage of high-steep rock slopes occurs at a rainfall intensity of 40 mm/h,whereas a rainfall exceeding 50 mm can induce critical instability and precipitation reaching up to 60 mm will result in slope *** improved region growing segmentation method(IRGSM)was subsequently employed for image recognition of rock mass deformation in underground *** an error comparison with the simple linear iterative cluster(SliC)superpixel method and the original region growing segmentation method(ORGSM)showed that the average identification error in the X and Y directions by the method was reduced significantly(1.82%and 1.80%in IRGSM;4.70%and 6.26%in SliC;9.45%and 12.40%in ORGSM).Ultimately,the relationship between rainfall intensity and failure probability was analyzed using the Monte Carlo ***,the stability assessment criteria of rock slope under unsaturated condition were quantitatively and accurately evaluated.

关键词： Open-pit to underground mining Rock slope Rainfall infiltration Excavation unloading Similar physical model Image recognition

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Effect of slope angle on fractured rock masses under combined influence of variable rainfall infiltration and excavation unloading

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第10期16卷 4154-4176页

作者： Xiaoshuang li qihang li Yunmin Wang Wei liu Di Hou Chun Zhu School of Urban Construction Changzhou UniversityChangzhou213164China College of Civil Engineering Qilu Institute of TechnologyJinan250200China School of Resources and Safety Engineering Chongqing UniversityChongqing400044China Sinosteel Maanshan General Institute of Mining Research Co.Ltd. Maanshan243000China Guizhou Survey and Design Research Institute for Water Resources and Hydropower Guiyang550001China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China

Intense precipitation infiltration and intricate excavation processes are crucial factors that impact the stability and security of towering and steep rock slopes within mining *** primary aim of this research was to investigate the progression of cumulative failure within a cracked rock formation,considering the combined effects of precipitation and excavation *** study was conducted in the Huangniuqian eastern mining area of the Dexing Copper Mine in Jiangxi Province,*** engineering geological investigation was conducted,a physical model experiment was performed,numerical calculations and theoretical analysis were conducted using the matrix discrete element method(Mat-DEM),and the deformation characteristics and the effect of the slope angle of a fractured rock mass under different scenarios were *** failure and instability mechanisms of the fractured rock mass under three slope angle models were *** experimental results indicate that as the slope angle increases,the combined effect of rainfall infiltration and excavation unloading is reduced.A novel approach to simulating unsaturated seepage in a rock mass,based on the van Genuchten model(VGM),has been *** to the vertical displacement observed in a similar physical experiment,the average relative errors associated with the slope angles of 45,50,and 55were 2.094%,1.916%,and 2.328%,***,the combined effect of rainfall and excavation was determined using the proposed ***,the accuracy of the numerical simulation was *** findings contribute to the seepage field in a meaningful way,offering insight that can inform and enhance existing methods and theories for research on the underlying mechanism of ultra-high and steep rock slope instability,which can inform the development of more effective risk management strategies.

关键词： Open-pit to underground excavation Rainfall infiltration Similarity simulation Numerical simulation Image recognition Slope angle

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Folate/Vitamin B Alleviates Hyperhomocysteinemia-Induced Alzheimer-like Pathologies in Rat Retina

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Neuroscience Bulletin 2019年第2期35卷 325-335页

作者： Jing Guo Shaozhou Ni qihang li Jian-Zhi Wang Ying Yang Department of Pathophysiology School of Basic Medicine and Collaborative Innovation Center for Brain Science Key Laboratory for Neurological Disorders of the Ministry of Education of China Tongji Medical College Huazhong University of Science and Technology Emergency Department Zhongnan Hospital of Wuhan University School of Optometry and Ophthalmology and Eye Hospital Wenzhou Medical College Co-innovation Center of Neuroregeneration Nantong University

Hyperhomocysteinemia(Hhcy) is an independent risk factor for Alzheimer's disease(AD). Visual dysfunction is commonly found and is positively correlated with the severity of cognitive defects in AD patients. Our previous study demonstrated that Hhcy induces memory deficits with AD-like tau and amyloid-b(Ab) pathologies in the hippocampus, and supplementation with folate and vitamin B12(FB) prevents the Hhcy-induced AD-like pathologies in the hippocampus. Here, we investigated whether Hhcy also induces AD-like pathologies in the retina and the effects of FB. An Hhcy rat model was produced by vena caudalis injection of homocysteine for14 days, and the effects of FB were assessed by simultaneous supplementation with FB in drinking water. We found that Hhcy induced vessel damage with Ab and taupathologies in the retina, while simultaneous supplementation with FB remarkably attenuated the Hhcy-induced tau hyperphosphorylation at multiple AD-related sites and Ab accumulation in the retina. The mechanisms involved downregulation of amyloid precursor protein(APP), presenilin-1, beta-site APP-cleaving enzyme 1, and protein phosphatase-2 A. Our data suggest that the retina may serve as a window for evaluating the effects of FB on hyperhomocysteinemia-induced Alzheimer-like pathologies.

关键词： Hyperhomocysteinemia Alzheimer’s disease Retina Folate Vitamin B12

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Technology inflow following high-speed railway:Evidence from Chinese cities

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Journal of Management Science and Engineering 2023年第4期8卷 570-583页

作者： Dayong liu Jie liu qihang li Nixuan Guo Tong Chen Qiaoran Menag College of Management and Economics Tianjin UniversityTianjin300072China Shandong University of Finance and Economics Jinan250014China Peking University HSBC School of Business 518055China

Urban development thrives from technology inflows,which refers to the transfer of highvalue technology from various cities to local *** asymmetry of technical information-rooted in the tacit knowledge inherent in technology-mandates that technology transfer is heavily dependent on interactions and communication among talented *** study examines the effect of China's high-speed railway(HSR)on technology inflow,with an emphasis on talent interaction in the technology transfer *** findings suggest that HSR mitigates cross-city commuting costs and facilitates face-to-face interactions between talent,thereby fostering an increase in technology inflows to various cities."Talent"use HSR to transfer knowledge to cities teeming with such talent ***,areas with robust intellectual property rights protection witness an upsurge in intercity technology transfer via *** study elucidates the macro-mechanism of urban technology flow from the perspective of public transportation offering valuable insights for technology market infrastructure and services.

关键词： HSR Technology inflow Talent interaction Public service Technology factor market

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Does geographic distance have a significant impact on enterprise financing costs?

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Journal of Geographical Sciences 2019年第12期29卷 1965-1980页

作者： SUN Wei li qihang li Bo Institute of Geographic Sciences and Natural Resources Research CASBeijing 100101China College of Resources and Environment UCASBeijing 100049China Shandong University of Finanee and Economics Jinan 250014China Inter national College of Busi ness and Tech no logy Tianjin Un iversity of TechnologyTianjin 300384China

As information technology has been applied more broadly and transportation infrastructure has improved,persistent debate has existed as to the question of whether geographic distance influences enterprise financing costs(EFCs).Through mining big data regarding industrial enterprises and commercial bank branches(CBBs)in the Beijing-Tianjin-Hebei region,this paper conducts quantitative analysis of correlation between the EFCs and their distance to CBBs as well as the number of CBBs within a 1–5 km radius,and investigates how geographic factors affect *** results indicate the following:(1)In overall terms,the shorter the distance to CBBs and the greater the number of CBBs within a 1–5 km radius,the lower the EFCs.(2)Distance to CBBs and number of CBBs within a 1–5 km radius significantly influence state-owned and non-state-owned enterprises,with the effect on non-state-owned enterprises being more pronounced.(3)The EFCs in Beijing and Tianjin are not correlated with distance to CBBs,and negatively correlated to the number of CBBs within a 1–5 km radius;the EFCs in Hebei Province are positively correlated with distance to CBBs,and negatively correlated with the number of CBBs within a 1–5 km radius.(4)Distance to CBBs has a more significant impact on enterprises engaged in heavy industry and labor-intensive industries,while there is not much difference between different industries in terms of how the number of CBBs within a 1–5 km radius affects them.

关键词： financial geography enterprise financing geographic distance Beijing-Tianjin-Hebei

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Large-Scale Carbon Dioxide Storage in Salt Caverns:Evaluation of Operation,Safety,and Potential in China

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Engineering 2024年第9期40卷 226-246页

作者： Wei liu Xiong Zhang Jifang Wan Chunhe Yang liangliang Jiang Zhangxin Chen Maria Jose Jurado Xilin Shi Deyi Jiang Wendong Ji qihang li State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China China Energy Digital Technology Group Co.Ltd. Beijing 100044China Institute of Rock and Soil Mechanics Chinese Academy of SciencesWuhan 430064China Department of Chemical and Petroleum Engineering University of CalgaryCalgaryAB T2N 1N4Canada Eastern Institute of Technology Ningbo 315200China Geosciences Barcelona CSIC Spanish National Research CouncilBarcelona 08028Spain

Underground salt cavern CO_(2) storage(SCCS)offers the dual benefits of enabling extensive CO_(2) storage and facilitating the utilization of CO_(2) resources while contributing the regulation of the carbon *** economic and operational advantages over traditional carbon capture,utilization,and storage(CCUS)projects make SCCS a more cost-effective and flexible *** the widespread use of salt caverns for storing various substances,differences exist between SCCS and traditional salt cavern energy storage in terms of gas-tightness,carbon injection,brine extraction control,long-term carbon storage stability,and site selection *** distinctions stem from the unique phase change characteristics of CO_(2) and the application scenarios of ***,targeted and forward-looking scientific research on SCCS is *** paper introduces the implementation principles and application scenarios of SCCS,emphasizing its connections with carbon emissions,carbon utilization,and renewable energy peak *** delves into the operational characteristics and economic advantages of SCCS compared with other CCUS methods,and addresses associated scientific *** this paper,we establish a pressure equation for carbon injection and brine extraction,that considers the phase change characteristics of CO_(2),and we analyze the pressure during carbon *** comparing the viscosities of CO_(2) and other gases,SCCS’s excellent sealing performance is *** on this,we develop a long-term stability evaluation model and associated indices,which analyze the impact of the injection speed and minimum operating pressure on *** countermeasures to ensure stability are *** selection criteria for SCCS are established,preliminary salt mine sites suitable for SCCS are identified in China,and an initial estimate of achievable carbon storage scale in China is made at over 51.8-77.7 million tons,utilizing only 20%-30%volume

关键词： Carbon-neutrality Salt cavern Large-scale CO_(2)storage Injection and withdrawal Stability analysis

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地理学视角的京津冀地区工业企业融资成本分析

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地理学报 2019年第6期74卷 1149-1162页

作者：李博李启航孙威中国科学院地理科学与资源研究所北京100101 天津理工大学国际工商学院天津300384 山东财经大学经济研究中心济南250014 中国科学院大学资源与环境学院北京100049

企业融资难和融资成本高是近年来制约中国实体经济发展的重要因素,但是哪些又是影响企业融资成本高的因素呢?基于京津冀地区商业银行分支机构和工业企业的大数据挖掘,定量分析了企业融资成本与商业银行分支机构的距离、1~5 km半径内商... 详细信息

企业融资难和融资成本高是近年来制约中国实体经济发展的重要因素,但是哪些又是影响企业融资成本高的因素呢?基于京津冀地区商业银行分支机构和工业企业的大数据挖掘,定量分析了企业融资成本与商业银行分支机构的距离、1~5 km半径内商业银行分支机构的数量的相关性,解释了地理因素对企业融资成本的作用机制。研究表明:①总体上看,与商业银行分支机构的距离越近、1~5 km半径内商业银行分支机构的数量越多,工业企业的融资成本越低。②与商业银行分支机构的距离、1~5 km半径内商业银行分支机构的数量对国有工业企业和非国有工业企业都有显著影响,其中对非国有工业企业的影响显著性更高。③北京和天津的工业企业融资成本与商业银行分支机构的距离无关,与1~5 km半径内商业银行分支机构的数量负相关;河北省的工业企业融资成本与商业银行分支机构的距离正相关,与1~5 km半径内商业银行分支机构的数量负相关。④与商业银行分支机构的距离对重工业企业和劳动密集型企业的影响更显著,1~5 km半径内商业银行分支机构的数量对不同行业的影响差异性不大。

关键词：金融地理银行企业融资地理距离京津冀

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环境激励下的旋转机械工作模态参数辨识

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机械工程学报 2019年第19期55卷 28-34页

作者：李启行褚福磊清华大学机械工程系

伴随着高速透平机械向大跨度、柔性结构方向发展,转子-轴承系统的稳定性将面临着严峻考验。在出厂测试阶段,确保机组转子系统具有足够稳定性裕度是降低生产现场机组发生失稳故障风险的重要手段。采用适用于随机平稳环境激励下的随机子... 详细信息

伴随着高速透平机械向大跨度、柔性结构方向发展,转子-轴承系统的稳定性将面临着严峻考验。在出厂测试阶段,确保机组转子系统具有足够稳定性裕度是降低生产现场机组发生失稳故障风险的重要手段。采用适用于随机平稳环境激励下的随机子空间法,对机组的模态参数进行辨识,可规避在转子非驱动端增设电磁激振器的传统测试方法。通过分析转子振型进动方向,区分一阶正反进动的模态参数。结合3-σ统计聚类算法,剔除非稳定的噪声或物理极点,形成了区分转子系统的正反进动的稳态图。数值仿真表明,随机子空间法可以有效地辨识系统的模态参数,利用旋转机械的振型进动方向分析方法可以区分正反进动。此外,通过传统扫频激励模态参数辨识试验,验证了随机子空间方法的辨识精度和工程测试可行性。研究结果可为透平机组的稳定性测试提供技术和理论支撑。

关键词：透平机械工作模态辨识随机激励转子稳定性

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地铁扣件螺旋道钉断裂过程分析及改进措施

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同济大学学报（自然科学版） 2016年第6期44卷 892-898页

作者：肖宏李启航北京交通大学土木建筑工程学院道路与铁道工程系北京100044 北京市轨道交通线路工程安全与防灾工程技术研究中心北京100044

引入扩展有限元方法,结合现场调研与实测数据,建立均匀受力理想状态和偏载受力不利工况下螺旋道钉扩展有限元模型,通过预设横向、竖向微裂纹以及单条和多条微裂纹工况,分析研究了扣件螺旋道钉的裂纹发展过程.结果表明,由于螺旋道钉的道... 详细信息

引入扩展有限元方法,结合现场调研与实测数据,建立均匀受力理想状态和偏载受力不利工况下螺旋道钉扩展有限元模型,通过预设横向、竖向微裂纹以及单条和多条微裂纹工况,分析研究了扣件螺旋道钉的裂纹发展过程.结果表明,由于螺旋道钉的道钉头部和螺杆结合部位存在较大的结构尺寸变化,导致了该处存在较大的应力集中,易萌生微裂纹,并在列车荷载长期作用下裂纹沿着横向扩展、贯通.对比看出,研究结果与实际扣件螺旋道钉的断裂形式相符,表明采用扩展有限元方法能很好地进行扣件螺旋道钉的断裂过程分析.此外,为避免和减少螺旋道钉的断裂发生,分13种工况研究了螺旋道钉肩胛过渡圆弧的设置.研究结果建议,对于T30×155型扣件螺旋道钉应设置1.6 mm半径的过渡圆弧,相对于不设置过渡圆弧,最大应力可减小40%.

关键词：螺旋道钉断裂过程扩展有限元法过渡圆弧

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