Constitutive models aimed at predicting the mechanical response of lead-core bearing devices for passive seismic isolation are discussed in this paper. The study is focused on single-degree-of-freedom models which pro...Constitutive models aimed at predicting the mechanical response of lead-core bearing devices for passive seismic isolation are discussed in this paper. The study is focused on single-degree-of-freedom models which provide a relation between the shear displacement （shear strain） and the shear force （shear stress） in elastomeric and lad-core rubber bearings. Classical Bouc-Wen model along with a numerical procedure for identification of the model constants is described. Alternatively, a constitutive relation introducing a damage variable aimed at assessing the material degradation is also considered.展开更多
Drill sampling has been widely employed as an effective way to acquire deep samples in extraterrestrial exploration. A novel sampling method, namely, flexible-tube coring, was adopted for the Chang＇e mission to acqui...Drill sampling has been widely employed as an effective way to acquire deep samples in extraterrestrial exploration. A novel sampling method, namely, flexible-tube coring, was adopted for the Chang＇e mission to acquire drilling cores without damaging stratification information. Since the extraterrestrial environment is uncertain and different from the terrestrial environment, automated drill sampling missions are at risk of failure. The principles of drilling and coring for the lunar subsurface should be fully tested and verified on earth before launch. This paper proposes a test-bed for conducting the aforementioned experiments on earth. The test-bed comprises a rotary-percussive drilling mechanism, penetrating mechanism, drilling medium container, and signal acquisition and control system. For granular soil, coring experiments indicate that the sampling method has a high coring rate greater than 80%. For hard rock, drilling experiments indicate that the percussive frequency greatly affects the drilling efficiency. A multi-layered simulant composed of granular soil and hard rock is built to test the adaptability of drilling and coring. To tackle complex drilling media, an intelligent drilling strategy based on online recognition is proposed to improve the adaptability of the sampling drill. The primary features of this research are the proposal of a scheme for drilling and coring a test-bed for validation on earth and the execution of drilling experiments in complex media.展开更多
Deep oil exploration coring technology cannot accurately maintain the in-situ pressure and temperature of samples, which leads to a distortion of deep oil and gas resource reserve evaluations based on conventional cor...Deep oil exploration coring technology cannot accurately maintain the in-situ pressure and temperature of samples, which leads to a distortion of deep oil and gas resource reserve evaluations based on conventional cores and cannot guide the development of deep oil and gas resources on Earth. The fundamental reason is the lack of temperature and pressure control in in-situ coring environments. In this paper, a pressure control method of a coring device is studied. The theory and method of deep intelligent temperature-pressure coupling control are innovatively proposed, and a multifield coupling dynamic sealing model is established. The optimal cardinality three term PID (Proportional-Integral-Differential) intelligent control algorithm of pressure system is developed. The temperature-pressure characteristic of the gas-liquid two-phase cavity is analyzed, and the pressure intelligent control is carried out based on three term PID control algorithms. An in-situ condition-preserved coring (ICP-Coring) device is developed, and an intelligent control system for the temperature and pressure of the coring device is designed and verified by experiments. The results show that the temperature-pressure coupling control system can effectively realize stable sealing under temperature-pressure fields of 140 MPa and 150 °C. The temperature-pressure coupling control method can accurately realize a constant pressure inside the coring device. The maximum working pressure is 140 MPa, and the effective pressure compensation range is 20 MPa. The numerical simulation experiment of pressure system control algorithm is carried out, and the optimal cardinality and three term coefficients are obtained. The pressure steady-state error is less than 0.01%. The method of temperature-pressure coupling control has guiding significance for coring device research, and is also the basis for temperature-pressure decoupling control in ICP-Coring.展开更多
Since its introduction,endoscopic ultrasound(EUS)guided fine needle aspiration and fine needle biopsy have become an indispensable tool for the diagnosis of lesions within the gastrointestinal tract and surrounding or...Since its introduction,endoscopic ultrasound(EUS)guided fine needle aspiration and fine needle biopsy have become an indispensable tool for the diagnosis of lesions within the gastrointestinal tract and surrounding organs.It has proved to be an effective diagnostic method with high accuracy and low complication rates.Several factors can influence the accuracy and the diagnostic yield of this procedure including experience of the endosonographer,availability of onsite cytopathology services,the method of cytopathology preparation,the location and physical characteristics of the lesion,sampling techniques and the type and size of the needle used.In this review we will outline the recent studies evaluating EUS-guided tissue acquisition and will provide practical recommendations to maximize tissue yield.展开更多
Against the global backdrop of carbon neutrality,a new energy revolution centered on renewable energy sources and artificial intelligence is imminent.China is leading this revolution through breakthroughs in three cor...Against the global backdrop of carbon neutrality,a new energy revolution centered on renewable energy sources and artificial intelligence is imminent.China is leading this revolution through breakthroughs in three core devices:lithiumion batteries(LIBs),fuel cells(FCs),and photovoltaic(PV)cells.In the field of LIBs,energy density has increased significantly while costs have decreased;all-solid-state batteries will continue to advance toward higher energy density and enhanced safety,and material recycling technologies will reduce carbon emissions.For FCs,system lifespan has improved,costs have dropped substantially,and application scenarios are expanding from transportation to diverse systems spanning water,land,air,and space.PV technology is transitioning to perovskite,with module costs expected to decline rapidly and tandem cell efficiency poised to reach new heights.At the system integration level,the market penetration rate of electric vehicles(EVs)has nearly reached 50%,making the development trend of pure electric drive irreversible.Vehicle-to-grid(V2G)interaction,by fully leveraging the residual lifespan value of EV batteries,is set to become the most widely distributed and lowest-cost energy storage resource on the user side.Meanwhile,hydrogen energy storage technology will enable large-scale,long-term energy transfer.EVs,electrochemical energy storage stations,and hydrogen energy storage will collectively play roles in short-,medium-,and long-term energy storage,addressing fluctuations and uncertainties in largescale renewable energy applications.By promoting scenariodriven industrial models,market-driven policy frameworks,and problem-oriented R&D approaches,the new energy revolution will ultimately form an economic ecosystem worth tens of trillions of yuan,reshaping the global energy landscape.展开更多
文摘Constitutive models aimed at predicting the mechanical response of lead-core bearing devices for passive seismic isolation are discussed in this paper. The study is focused on single-degree-of-freedom models which provide a relation between the shear displacement （shear strain） and the shear force （shear stress） in elastomeric and lad-core rubber bearings. Classical Bouc-Wen model along with a numerical procedure for identification of the model constants is described. Alternatively, a constitutive relation introducing a damage variable aimed at assessing the material degradation is also considered.
基金Supported by National Natural Science Foundation of China(Grant No.51105092)Introducing Talents of Discipline to Universities(111 Program,Grant No.B07018)+1 种基金Heilongjiang Postdoctoral Grant(Grant No.LBHZ11168)China Postdoctoral Science Foundation(Grant No.2012M520722)
文摘Drill sampling has been widely employed as an effective way to acquire deep samples in extraterrestrial exploration. A novel sampling method, namely, flexible-tube coring, was adopted for the Chang＇e mission to acquire drilling cores without damaging stratification information. Since the extraterrestrial environment is uncertain and different from the terrestrial environment, automated drill sampling missions are at risk of failure. The principles of drilling and coring for the lunar subsurface should be fully tested and verified on earth before launch. This paper proposes a test-bed for conducting the aforementioned experiments on earth. The test-bed comprises a rotary-percussive drilling mechanism, penetrating mechanism, drilling medium container, and signal acquisition and control system. For granular soil, coring experiments indicate that the sampling method has a high coring rate greater than 80%. For hard rock, drilling experiments indicate that the percussive frequency greatly affects the drilling efficiency. A multi-layered simulant composed of granular soil and hard rock is built to test the adaptability of drilling and coring. To tackle complex drilling media, an intelligent drilling strategy based on online recognition is proposed to improve the adaptability of the sampling drill. The primary features of this research are the proposal of a scheme for drilling and coring a test-bed for validation on earth and the execution of drilling experiments in complex media.
基金supported by the National Natural Science Foundation of China(grant numbers 51827901,51805340)funded by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)Shenzhen Basic Research Program(General Program)(No.JCYJ20190808153416970).
文摘Deep oil exploration coring technology cannot accurately maintain the in-situ pressure and temperature of samples, which leads to a distortion of deep oil and gas resource reserve evaluations based on conventional cores and cannot guide the development of deep oil and gas resources on Earth. The fundamental reason is the lack of temperature and pressure control in in-situ coring environments. In this paper, a pressure control method of a coring device is studied. The theory and method of deep intelligent temperature-pressure coupling control are innovatively proposed, and a multifield coupling dynamic sealing model is established. The optimal cardinality three term PID (Proportional-Integral-Differential) intelligent control algorithm of pressure system is developed. The temperature-pressure characteristic of the gas-liquid two-phase cavity is analyzed, and the pressure intelligent control is carried out based on three term PID control algorithms. An in-situ condition-preserved coring (ICP-Coring) device is developed, and an intelligent control system for the temperature and pressure of the coring device is designed and verified by experiments. The results show that the temperature-pressure coupling control system can effectively realize stable sealing under temperature-pressure fields of 140 MPa and 150 °C. The temperature-pressure coupling control method can accurately realize a constant pressure inside the coring device. The maximum working pressure is 140 MPa, and the effective pressure compensation range is 20 MPa. The numerical simulation experiment of pressure system control algorithm is carried out, and the optimal cardinality and three term coefficients are obtained. The pressure steady-state error is less than 0.01%. The method of temperature-pressure coupling control has guiding significance for coring device research, and is also the basis for temperature-pressure decoupling control in ICP-Coring.
文摘Since its introduction,endoscopic ultrasound(EUS)guided fine needle aspiration and fine needle biopsy have become an indispensable tool for the diagnosis of lesions within the gastrointestinal tract and surrounding organs.It has proved to be an effective diagnostic method with high accuracy and low complication rates.Several factors can influence the accuracy and the diagnostic yield of this procedure including experience of the endosonographer,availability of onsite cytopathology services,the method of cytopathology preparation,the location and physical characteristics of the lesion,sampling techniques and the type and size of the needle used.In this review we will outline the recent studies evaluating EUS-guided tissue acquisition and will provide practical recommendations to maximize tissue yield.
文摘Against the global backdrop of carbon neutrality,a new energy revolution centered on renewable energy sources and artificial intelligence is imminent.China is leading this revolution through breakthroughs in three core devices:lithiumion batteries(LIBs),fuel cells(FCs),and photovoltaic(PV)cells.In the field of LIBs,energy density has increased significantly while costs have decreased;all-solid-state batteries will continue to advance toward higher energy density and enhanced safety,and material recycling technologies will reduce carbon emissions.For FCs,system lifespan has improved,costs have dropped substantially,and application scenarios are expanding from transportation to diverse systems spanning water,land,air,and space.PV technology is transitioning to perovskite,with module costs expected to decline rapidly and tandem cell efficiency poised to reach new heights.At the system integration level,the market penetration rate of electric vehicles(EVs)has nearly reached 50%,making the development trend of pure electric drive irreversible.Vehicle-to-grid(V2G)interaction,by fully leveraging the residual lifespan value of EV batteries,is set to become the most widely distributed and lowest-cost energy storage resource on the user side.Meanwhile,hydrogen energy storage technology will enable large-scale,long-term energy transfer.EVs,electrochemical energy storage stations,and hydrogen energy storage will collectively play roles in short-,medium-,and long-term energy storage,addressing fluctuations and uncertainties in largescale renewable energy applications.By promoting scenariodriven industrial models,market-driven policy frameworks,and problem-oriented R&D approaches,the new energy revolution will ultimately form an economic ecosystem worth tens of trillions of yuan,reshaping the global energy landscape.
