At 09:15 local time on May 13,2018 in the Republic of Mozambique,Li Zhanshu,a member of the Standing Committee of the Political Bureau of the CPC Central Committee and Chairman of the Standing Committee of the Nationa...At 09:15 local time on May 13,2018 in the Republic of Mozambique,Li Zhanshu,a member of the Standing Committee of the Political Bureau of the CPC Central Committee and Chairman of the Standing Committee of the National People's Congress (NPC),and Veronica Macamo,Speaker of the Republic of Mozambique,attended the founding ceremony of the Chinese aid project for the Confucius Institute and Media Arts Institute in Mozambique.展开更多
The construction of water conservancy projects should commence during optimal atmospheric conditions and non-flood period to ensure completion before the flood season begin in summer.In most areas of Northern China,th...The construction of water conservancy projects should commence during optimal atmospheric conditions and non-flood period to ensure completion before the flood season begin in summer.In most areas of Northern China,the temperature during winter remain at lower level,in which environmental factors play the most important role in the construction of water conservancy projects.In particular,low temperature directly affects the strength of concrete and delays its solidification,this highly affects the quality and progress of concrete construction.In order to overcome this barrier,better planning,for reasonable and effective construction techniques and targeted control measures should be adopted to reduce the adverse effects of low temperature to assure a strong and safe architecture.展开更多
The Jiangyin Yangtze River Crossing Project sets up a record with the length of horizontal directional drilling(HDD)of 3300 m in the world.Inevitably,many technical difficulties might exist in pilot hole docking,reami...The Jiangyin Yangtze River Crossing Project sets up a record with the length of horizontal directional drilling(HDD)of 3300 m in the world.Inevitably,many technical difficulties might exist in pilot hole docking,reaming torque,property requirement and recovery of drilling fluids,and pullback resistance.Accordingly,some innovative measures were taken in each stage.At the pilot hole drilling stage,a reasonable drill tool assembly was chosen,namely,a new type ofØ193.7 mm(S-135)drill pipe with high-strength was applied along with the fully guided cable and rotating magnate docking technologies.At the reaming stage,an innovativeØ168.3 mm(V-150)drill pipe was adopted along with the optimized reamers and the improved hydraulic parameters to successfully reduce the reaming torque and significantly improve the reaming efficiency.At the pullback stage,a specific ground anchor was designed for large-tonnage pullback resistance,and drift pipe,super lubricants and novel glass fiber reinforced plastics were combined for protecting the pipeline coating.Finally,the drilling fluid formula was optimally selected to ensure the hole stability and flowback of drilling cuttings,and a centrifugal was used to recycle the drilling mud to ensure its necessary performance.All these measures not only ensured the success of this HDD project,but also broke many records in this respect.展开更多
Karst fractures serve as crucial seepage channels and storage spaces for carbonate natural gas reservoirs,and electrical image logs are vital data for visualizing and characterizing such fractures.However,the conventi...Karst fractures serve as crucial seepage channels and storage spaces for carbonate natural gas reservoirs,and electrical image logs are vital data for visualizing and characterizing such fractures.However,the conventional approach of identifying fractures using electrical image logs predominantly relies on manual processes that are not only time-consuming but also highly subjective.In addition,the heterogeneity and strong dissolution tendency of karst carbonate reservoirs lead to complexity and variety in fracture geometry,which makes it difficult to accurately identify fractures.In this paper,the electrical image logs network(EILnet)da deep-learning-based intelligent semantic segmentation model with a selective attention mechanism and selective feature fusion moduledwas created to enable the intelligent identification and segmentation of different types of fractures through electrical logging images.Data from electrical image logs representing structural and induced fractures were first selected using the sliding window technique before image inpainting and data augmentation were implemented for these images to improve the generalizability of the model.Various image-processing tools,including the bilateral filter,Laplace operator,and Gaussian low-pass filter,were also applied to the electrical logging images to generate a multi-attribute dataset to help the model learn the semantic features of the fractures.The results demonstrated that the EILnet model outperforms mainstream deep-learning semantic segmentation models,such as Fully Convolutional Networks(FCN-8s),U-Net,and SegNet,for both the single-channel dataset and the multi-attribute dataset.The EILnet provided significant advantages for the single-channel dataset,and its mean intersection over union(MIoU)and pixel accuracy(PA)were 81.32%and 89.37%,respectively.In the case of the multi-attribute dataset,the identification capability of all models improved to varying degrees,with the EILnet achieving the highest MIoU and PA of 83.43%and 91.11%,respectively.Further,applying the EILnet model to various blind wells demonstrated its ability to provide reliable fracture identification,thereby indicating its promising potential applications.展开更多
Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,...Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,the migration behavior of temporary plugging agent(TPA),as a function of the concentration and particle size of TPA and cluster-perforation numbers,etc.,determining the effectiveness of this technique,remains unclear.Therefore,this study conducted innovatively a series of TPDF simulation experiments on transparent polymethyl methacrylate(PMMA)specimens(cubic block of 30 cm×30 cm×30 cm)to explore visually the migration behavior of TPA in multi-clustered HFs in a horizontal well.A laboratory hydraulic sandblasting perforation completion technique was implemented to simulate the multi-cluster perforations.All the distributions of wellbore,perforations,HFs,and TPA can be seen clearly inside the PMMA specimen post the experiment.The results show that there are four characteristic plugging positions for the TPA:mouth of HF,middle of HF,tip of HF,and the intersection of HFs.Small particle size TPA tends to migrate to the fracture tip for plugging,while large particle size TPA tends to plug at the fracture mouth.The migration of the TPA is influenced obviously by the morphology of the fracture wall.A smooth fracture wall is conducive to the migration of the TPA to the far end of HFs,but not conducive to generating the plugging zone and HF diversion.In contrast,a"leaf vein"fracture of rough wall is conducive to generating the plugging layer and the diversion of HFs,but not conducive to the migration of the TPA to the far end of HFs.The migration ability of TPA in a"shell"pattern is intermediate between the two above cases.Increasing TPA concentration can encourage TPA to migrate more quickly to the characteristic plugging position,and thereby to promote the creation of effective plugging and subsequently the multi-stage diversion of the HFs.Nevertheless,excessive concentration may cause the TPA to settle prematurely,affecting the propagation of the HFs to the far end.Increasing the number of clusters to a certain extent can encourage TPA to migrate into the HFs and form plugging,and promote the diversion.An evaluation system for the migration ability of granular TPA has been established,and it was calculated that when there is no plugging expectation target,the comprehensive migration ability of small particle size TPA is stronger than that of large particle size TPA.This research provides theoretical foundation for the optimization of temporary plugging parameters.展开更多
Shale gas reservoirs typically contain numerous nanoscale pores,with pore size playing a significant role in influencing the gas behavior.To better understand the related mechanisms,this study employs the Gauge-GEMC m...Shale gas reservoirs typically contain numerous nanoscale pores,with pore size playing a significant role in influencing the gas behavior.To better understand the related mechanisms,this study employs the Gauge-GEMC molecular simulation method to systematically analyze the effects of various pore sizes(5,10,20,and 40 nm)on the phase behavior and dew point pressure of the shale gas reservoir components.The simulation results reveal that when pore sizes are smaller than 40 nm,the dew point pressure increases significantly as the pore size decreases.For instance,the dew point pressure in 5 nmpores is 20.3%higher than undermacroscopic conditions.Additionally,larger hydrocarbon molecules exhibit a tendency to aggregate in smaller pores,particularly in the 5–10 nm range,where the relative concentration of heavy hydrocarbons(C_(4+))increases markedly.Moreover,as the pore size becomes larger,the component distribution gradually aligns with experimental results observed under macroscopic conditions.This study demonstrates that pore effects are more pronounced for smaller sizes,directly influencing the aggregation of heavy hydrocarbons and the rise in dew point pressure.These phenomena could significantly impact the diffusivity of shale gas reservoirs and the recovery of condensate gas.The findings provide new theoretical insights into phase behavior changes in nanopores,offering valuable guidance for optimizing shale gas reservoir extraction strategies.展开更多
Fluid channeling caused by seal failure at the cement sheath-formation interface during fracturing is a severe problem in oil gas wells.In this study,a novel model was developed to evaluate interface sealing integrity...Fluid channeling caused by seal failure at the cement sheath-formation interface during fracturing is a severe problem in oil gas wells.In this study,a novel model was developed to evaluate interface sealing integrity.The model's accuracy was verified based on a self-developed interface seal evaluation device and an experiment.Subsequently,the interface seal under different formation conditions was investigated using this model.The theoretical calculation showed that for a cement sheath-carbonate formation interface,the channeling of acid-fracturing fluid caused interface seal failure and sustained casing pressure in the annulus space between the technical casing and formation.Mutual channeling between the fracturing sections occurred at the cement sheathshale formation interface during fracturing.For a sandstone formation,the interface seal failure caused the channeling between a water-bearing formation and a sandstone formation.Aiming at different formation conditions,the mechanical properties requirements of Young's modulus and Poisson's ratio of cement sheath were proposed respectively to ensure its seal integrity.The proposed model and method can be used to evaluate and optimize sealing integrity during fracturing.展开更多
Bipolar plate is one of the key components of Proton Exchange Membrane Fuel Cell(PEMFC)and a reasonable flow field design for bipolar plate will improve cell performance.Herein,we have reviewed conventional and bionic...Bipolar plate is one of the key components of Proton Exchange Membrane Fuel Cell(PEMFC)and a reasonable flow field design for bipolar plate will improve cell performance.Herein,we have reviewed conventional and bionic flow field designs in recent literature with a focus on bionic flow fields.In particular,the bionic flow fields are summarized into two types:plant-inspired and animal-inspired.The conventional methodology for flow field design takes more time to find the optimum since it is based on experience and trial-and-error methods.In recent years,machine learning has been used to optimize flow field structures of bipolar plates owing to the advantages of excellent prediction and optimization capability.Artificial Intelligence(AI)-assisted flow field design has been summarized into two categories in this review:single-objective optimization and multi-objective optimization.Furthermore,a Threats-Opportunities-Weaknesses-Strengths(TOWS)analysis has been conducted for AI-assisted flow field design.It has been envisioned that AI can afford a powerful tool to solve the complex problem of bionic flow field design and significantly enhance the performance of PEMFC with bionic flow fields.展开更多
Field development practices in many shale gas regions(e.g.,the Changning region)have revealed a persistent issue of suboptimal reserve utilization,particularly in areas where the effective drainage width of production...Field development practices in many shale gas regions(e.g.,the Changning region)have revealed a persistent issue of suboptimal reserve utilization,particularly in areas where the effective drainage width of production wells is less than half the inter-well spacing(typically 400-500 m).To address this,infill drilling has become a widely adopted and effective strategy for enhancing reservoir contact andmobilizing previously untapped reserves.However,this approach has introduced significant inter-well interference,complicating production dynamics and performance evaluation.The two primary challenges hindering efficient deployment of infill wells are:(1)the quantitative assessment of hydraulic and pressure connectivity between infill wells and their associated parent wells,and(2)the accurate estimation of platform-scale Estimated Ultimate Recovery(EUR)following infill implementation.This study presents a novel framework to quantify inter-well connectivity by deriving a material balance equation tailored for shale gas infill well groups,explicitly incorporating gas adsorption and desorption mechanisms.The model simultaneously evaluates formation pressure evolution and crossflow behavior between wells,offering a robust analytical basis for performance prediction.For infill wells intersecting the drainage boundaries of parent wells,EUR is estimated using an analytical model developed for multi-stage hydraulically fractured horizontal wells.Meanwhile,the EUR of the parent wells is obtained by summing their pre-infill EUR with the final inter-well crossflow contribution.展开更多
The ocean,as one of Earth’s largest natural resources,covers over 70% of the planet’s surface and holds vast water energy potential.Building on this context,this study designs a hybrid generator(WWR-TENG)that integr...The ocean,as one of Earth’s largest natural resources,covers over 70% of the planet’s surface and holds vast water energy potential.Building on this context,this study designs a hybrid generator(WWR-TENG)that integrates a triboelectric nanogenerator(TENG)and an electromagnetic generator(EMG).TENG is a new technology that can capture mechanical energy from the environment and convert it into electrical energy,and is particularly suitable for common natural or man-made power sources such as human movement,wind power,and water flow.EMG is a device that converts mechanical energy into electrical energy through the principle of electromagnetic induction and can usually provide stable power output.The composite design leverages the complementary advantages of both technologies to efficiently capture and convert marine wave energy.By combining the TENG’s high energy conversion efficiency,lowcost,lightweight structure,and simple designwith the EMG’s capabilities,the systemprovides a sustainable solution for marine energy development.Experimental results demonstrate that at a rotational speed of 3.0 r/s,the TENG component of the WWR-TENG achieves an open-circuit voltage of approximately 280 V and a shortcircuit current of 20μA.At the same time,the EMG unit exhibits an open-circuit voltage of 14 V and a short-circuit current of 14 mA.Furthermore,when integrated with a power management circuit,the WWR-TENG charges a 680μF capacitor to 3 V within 10 s at a rotational speed of 3.0 r/s.A simulated wave environment platform was established,enabling the WWR-TENG to maintain the thermo-hygrometer in normal operation under simulated wave conditions.These findings validate the hybrid system’s effectiveness in harnessing and storingwave energy,highlighting its potential for practical marine energy applications.展开更多
Assessment of water quality by firefly algorithm based on BP neural network model(FA-BP model)is built.In this model,the evaluation index function is constructed by BP Artificial Neural Network Algorithm(BP model),and...Assessment of water quality by firefly algorithm based on BP neural network model(FA-BP model)is built.In this model,the evaluation index function is constructed by BP Artificial Neural Network Algorithm(BP model),and Firefly Algorithm(FA model)is introduced to optimize weight values and thresholds to find the optimal solution.Fuzzy Comprehensive Evaluation method,Grey Incidence Analysis Algorithm and FA-BP model will be applied to evaluate the water quality of the five main rivers in Lianyungang City including Longwei,Yudai,Dapu,Paidan,and Dongyan River.The results show that the Fuzzy Comprehensive Evaluation method is difficult to use for slight pollution rivers with several slightly over standard indexes.It will be easy to ignore the impact of extreme indexes by Grey Incidence Analysis Algorithm.FA-BP model solves the shortcomings of the two methods.The evaluation results provide an important reference for the formulation of reasonable measures.It is a relatively comprehensive evaluation method and has a good application prospect in water quality evaluation.展开更多
The uniform corrosion behavior of model FeCrAl alloys as well as commercial Zircaloy-4 as reference material were investigated in 360℃borated and lithiated water.The results reveal that FeCrAl alloys exhibited better...The uniform corrosion behavior of model FeCrAl alloys as well as commercial Zircaloy-4 as reference material were investigated in 360℃borated and lithiated water.The results reveal that FeCrAl alloys exhibited better corrosion resistance than Zircaloy-4.It is found that the oxide films formed on the FeCrAl alloys are composed of outer Fe_(3)O_(4)layer,inner layer consisting of compact spinel layer and porous spinel layer,and transition layer containing Al-Cr-rich oxides and matrix enriched with Fe°.The spinel oxides in the inner layer are FeFe_(2-x-y-z)Cr_(x)Al_(y)MozO_(4).The corrosion mechanism of FeCrAl alloys in high temperature water is discussed.展开更多
This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion w...This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion with multi-cluster sand jetting perforation.The effects of temporary plugging agent(TPA)particle size,TPA concentration,single-cluster perforation number and cluster number on plugging pressure,multi-fracture diversion pattern and distribution of TPAs were investigated.A combination of TPAs with small particle sizes within the fracture and large particle sizes within the segment is conducive to increasing the plugging pressure and promoting the diversion of multi-fractures.The addition of fibers can quickly achieve ultra-high pressure,but it may lead to longitudinal fractures extending along the wellbore.The temporary plugging peak pressure increases with an increase in the concentration of the TPA,reaching a peak at a certain concentration,and further increases do not significantly improve the temporary plugging peak pressure.The breaking pressure and temporary plugging peak pressure show a decreasing trend with an increase in single-cluster perforation number.A lower number of single-cluster perforations is beneficial for increasing the breaking pressure and temporary plugging peak pressure,and it has a more significant control on the propagation of multi-cluster fractures.A lower number of clusters is not conducive to increasing the total number and complexity of artificial fractures,while a higher number of clusters makes it difficult to achieve effective plugging.The TPAs within the fracture is mainly concentrated in the complex fracture areas,especially at the intersections of fractures.Meanwhile,the TPAs within the segment are primarily distributed near the perforation cluster apertures which initiated complex fractures.展开更多
The relationship between paleogeographic pattern and sedimentary differentiation of evaporite-carbonate symbiotic system is examined based on logging,core and thin section data,by taking the sixth sub-member of fifth ...The relationship between paleogeographic pattern and sedimentary differentiation of evaporite-carbonate symbiotic system is examined based on logging,core and thin section data,by taking the sixth sub-member of fifth member of Ordovician Majiagou Formation(M56)in the central-eastern Ordos Basin as an example.(1)Seven sub-geomorphic units(Taolimiao west low,Taolimiao underwater high,Taolimiao east low,Hengshan high,East salt low,North slope and Southwest slope)developed in the study area.(2)The“three lows”from west to east developed dolomitic restricted lagoon,evaporite evaporative lagoon and salt evaporative lagoon sedimentary facies respectively,the"two highs"developed high-energy grain beach and microbial mound,and the north and south slopes developed dolomitic flats around land.(3)The paleogeographic pattern caused natural differentiation of replenishment seawater from the northwest Qilian sea,leading to the eccentric sedimentary differentiation of dolomite,evaporite and salt rock symbiotic system from west to east,which is different from the classic“bull's eye”and“tear drop”distribution patterns.(4)As the Middle Qilian block subducted and collided into the North China Plate,the far-end compression stress transferred,giving rise to the alternate highland and lowland in near north to south direction during the sedimentary period of M56 sub-member.(5)Taolimiao underwater high and Hengshan high developed favorable zones of microbial mounds and grain shoals in south to north strike in M56 sub-member,making them favorable exploration areas with great exploration potential in the future.展开更多
To study the casing deformation(CD)in shale gas well fracturing caused by natural fracture slip,a fracture face stress model is built based on stress analysis,and a CD prediction model is established based on complex ...To study the casing deformation(CD)in shale gas well fracturing caused by natural fracture slip,a fracture face stress model is built based on stress analysis,and a CD prediction model is established based on complex function to analyze factors affecting wellbore shear stress and CD.(1)The fracture and wellbore approach angles have significant impacts on the wellbore shear stress.In Weiyuan shale gas field,Sichuan Basin,under the common wellbore approach angle of nearly 90°,the wellbore is subjected to large shear stress and high risk of CD at the fracture approach angle range of 20° to 55° or its supplementary angle range.(2)When the fracture is partially opened,the wellbore shear stress is positively correlated with the fluid pressure,and negatively correlated with the fracture friction coefficient;when the fracture is fully opened,the wellbore shear stress is positively correlated with the natural fracture area.(3)The lower the elastic modulus and the longer the fracture length,the more serious the CD will be,and the Poisson’s ratio has a weak influence on the CD.The deformation first increases and then decreases with the increase of fracture approach angle,and reaches the maximum when the fracture approach angle is 45°.(4)At a given fracture approach angle,appropriately adjusting the wellbore approach angle can avoid high shear stress acting on wellbore,and reasonable control of the fluid pressure in the fracture can reduce the CD risk.The shear stress acting on casing is usually much greater than the shear strength of casing,so increasing casing strength or cementing quality have limited effect on reducing the risk of CD.Caliper logging data has verified that the CD prediction model is reliable,so the model can be used to establish risk analysis chart and calculate deformation value,to provide a reference for quick CD risk prediction in fracturing design.展开更多
Pencil hardness testing,electrochemical impedance spectroscopy,scanning electron microscopy,and scanning Kelvin probe microscopy were used to study the local corrosion characteristics of a graphene-oxide-modified inne...Pencil hardness testing,electrochemical impedance spectroscopy,scanning electron microscopy,and scanning Kelvin probe microscopy were used to study the local corrosion characteristics of a graphene-oxide-modified inner coating.The effect of chloride concentration on the corrosion of the damaged inner coating was studied.The effects of chloride ions on damaged internal coatings and graphene-oxide-modified internal coatings were investigated.It was proposed to add graphene oxide into the epoxy coating to effectively inhibit the metal corrosion at the breakage.Because of the existence of graphene oxide(GO),the modified coating had a better physical property and had the effective infiltration of H2O and Cl^- into the coating.The results showed that graphene oxide coatings can give X80 steel better corrosion resistance in sodium chloride solution.展开更多
According to the blasting construction of the diaphragm wall of Puxi approaching section of East Fuxing Road river-crossing tunnel, the monitoring project of the vibration of the existing tun-nel induced by the blasti...According to the blasting construction of the diaphragm wall of Puxi approaching section of East Fuxing Road river-crossing tunnel, the monitoring project of the vibration of the existing tun-nel induced by the blasting construction is put forward, which includes the sensors’ location, moni-tor method and the vibration monitoring system. Based on the monitoring data of the explosion vibration, the vibration wave forms, velocities, acceleration responses, main frequencies and fields of measure points are analyzed under the conditions of three locations and different charge quanti-ties. According to the safety-judging standard of explosion vibration, the conclusion that the exist- ing tunnel is safe under the explosion vibration is then drawn. Furthermore, the spectrum character-istics of three explosion vibrations and the spectrum changing properties of explosion vi-bration wave transmitting in different directions are concluded, which can provide reference to similar projects.展开更多
BACKGROUND Catheter ablation for atrial fibrillation(AF)is commonly performed worldwide.However,the clinical charac-teristics of hospitalized patients with AF and national trends in catheter ablation at tertiary hospi...BACKGROUND Catheter ablation for atrial fibrillation(AF)is commonly performed worldwide.However,the clinical charac-teristics of hospitalized patients with AF and national trends in catheter ablation at tertiary hospitals in China remain unreported.METHODS This study used the Chinese national database(Hospital Quality Monitoring System)from 2013 to 2016,which is a mandatory database that collects the front page of patients’medical records for hospital accreditation,to describe the clinical cha-racteristics of patients with AF as an overall cohort and as subgroups divided by catheter ablation and sex.RESULTS Of 597,919 AF patients first admitted,57,983 patients underwent catheter ablation[56,384 cases(97.2%)of radiofre-quency ablation and 1599 cases(2.8%)of cryoablation]at 746 tertiary hospitals.Nearly 10%of patients hospitalized with AF at ter-tiary hospitals in China underwent catheter ablation,and the percentage of patients undergoing catheter ablation was on the rise bet-ween 2013 and 2016,and the number of cases increased by 2.5 times.Compared with AF patients who did not undergo catheter ablation,those who did were younger,more frequently male,and had fewer baseline comorbidities.Although the overall CHA_(2)DS_(2)-VASc score revealed over half of the patients were high-risk,patients who underwent catheter ablation were mostly low-risk(71.2%of males and 59.1%of females).Considering in-hospital adverse events,the overall pericardial tamponade and all-cause death incidences were 0.2%(0.6%in the ablation group)and 1.2%(0.1%in the ablation group),respectively;both of which were higher in females than males.CONCLUSIONS In this study,AF patients who underwent catheter ablation were relatively young,had a low thrombosis risk,and had few comorbidities and adverse events.Females were older and experienced more complications than males.展开更多
Long-term kinematic research of slow- moving debris slide is rare despite of the widespread global distribution of this kind. This paper presents a study of the kinematics and mechanism of the Jinpingzi debris slide l...Long-term kinematic research of slow- moving debris slide is rare despite of the widespread global distribution of this kind. This paper presents a study of the kinematics and mechanism of the Jinpingzi debris slide located on the Jinsha river bank in southwest China. This debris slide is known to have a volume of 27×106 ms in active state for at least one century. Field survey and geotechnical investigation were carried out to define the structure of the landslide. The physical and mechanical properties of the landslide materials were obtained by in-situ and laboratory tests. Additionally, surface and subsurface displacements, as well as groundwater level fluctuations, were monitored since 2005. Movement features, especially the response of the landslide movement to rainfall, were analysed. Relationships between resisting forces and driving forces were analysed by using the limit equilibrium method assuming rigid-plastic frictional slip. The results confirmed a viscous comoonent in the long-term continuous movement resulting in the quasioverconsolidated state of the slip zone with higher strength parameters than some other types of slowmoving landslides. Both surface and subsurface displacements showed an advancing pattern by the straight outwardly inclined （rather than gently or reversely inclined） slip zone, which resulted in low resistance to the entire sliding mass. The average surface displacement rate from 2005 to 2016 was estimated to be 0.19-0.87 mm/d. Basal sliding on the silty clay seam accounted for most of the deformation with different degrees of internal deformation in different parts. Rainfall was the predominant factor affecting the kinematics of Jinpingzi landslide while the role of groundwater level, though positive, was not significant. The response of the groundwater level to rainfall infiltration was not apparent. Unlike some shallow slow-moving earth flows or mudslides, whose behaviors are directly related to the phreatic groundwater level, the mechanism for Jinpingzi landslide kinematics is more likely related to the changing weight of the sliding mass and the downslope seepage pressure in the shallow soil mass resulting from rainfall events.展开更多
Thermoelectric generators(TEGs)are considered promising devices for waste heat recovery from various systems.The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer rec...Thermoelectric generators(TEGs)are considered promising devices for waste heat recovery from various systems.The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer receiver(FDR)of an air conditioning(A/C)system,which would otherwise go to waste.The study aims to build a set of thermoelectric generators(TEG)to collect the waste heat of the FDR and generate low-power electricity.A novel electrical circuit with two transformers is designed and fabricated to produce a more stable voltage for operation and charging.The thermoelectric generator(TEGs)was installed on the FDR of the A/C unit.The test showed that climate conditions have a significant impact on the output power generated from the system.The results showed that the peak voltage recorded in the current study is 5.2 V per day(wet,cold,and wind weather)with an output power of 0.2 W.These values are acceptable for powering the load and charging a single battery with 3.5 V as the voltage increases battery 0.1 V/20 min charge.A case study of operating the emergency signs in a building was considered.The current heat recovery system is deemed to be easily installed and can be connected to a network of TEGs to produce more power.展开更多
文摘At 09:15 local time on May 13,2018 in the Republic of Mozambique,Li Zhanshu,a member of the Standing Committee of the Political Bureau of the CPC Central Committee and Chairman of the Standing Committee of the National People's Congress (NPC),and Veronica Macamo,Speaker of the Republic of Mozambique,attended the founding ceremony of the Chinese aid project for the Confucius Institute and Media Arts Institute in Mozambique.
文摘The construction of water conservancy projects should commence during optimal atmospheric conditions and non-flood period to ensure completion before the flood season begin in summer.In most areas of Northern China,the temperature during winter remain at lower level,in which environmental factors play the most important role in the construction of water conservancy projects.In particular,low temperature directly affects the strength of concrete and delays its solidification,this highly affects the quality and progress of concrete construction.In order to overcome this barrier,better planning,for reasonable and effective construction techniques and targeted control measures should be adopted to reduce the adverse effects of low temperature to assure a strong and safe architecture.
基金China Petroleum Pipeline Bureau“Research on Long Distance(3300 m)Directional Drilling Crossing and Lithostratigraphic Positive Reaming Technologies”(No.2010-03).
文摘The Jiangyin Yangtze River Crossing Project sets up a record with the length of horizontal directional drilling(HDD)of 3300 m in the world.Inevitably,many technical difficulties might exist in pilot hole docking,reaming torque,property requirement and recovery of drilling fluids,and pullback resistance.Accordingly,some innovative measures were taken in each stage.At the pilot hole drilling stage,a reasonable drill tool assembly was chosen,namely,a new type ofØ193.7 mm(S-135)drill pipe with high-strength was applied along with the fully guided cable and rotating magnate docking technologies.At the reaming stage,an innovativeØ168.3 mm(V-150)drill pipe was adopted along with the optimized reamers and the improved hydraulic parameters to successfully reduce the reaming torque and significantly improve the reaming efficiency.At the pullback stage,a specific ground anchor was designed for large-tonnage pullback resistance,and drift pipe,super lubricants and novel glass fiber reinforced plastics were combined for protecting the pipeline coating.Finally,the drilling fluid formula was optimally selected to ensure the hole stability and flowback of drilling cuttings,and a centrifugal was used to recycle the drilling mud to ensure its necessary performance.All these measures not only ensured the success of this HDD project,but also broke many records in this respect.
基金the National Natural Science Foundation of China(42472194,42302153,and 42002144)the Fundamental Research Funds for the Central Univer-sities(22CX06002A).
文摘Karst fractures serve as crucial seepage channels and storage spaces for carbonate natural gas reservoirs,and electrical image logs are vital data for visualizing and characterizing such fractures.However,the conventional approach of identifying fractures using electrical image logs predominantly relies on manual processes that are not only time-consuming but also highly subjective.In addition,the heterogeneity and strong dissolution tendency of karst carbonate reservoirs lead to complexity and variety in fracture geometry,which makes it difficult to accurately identify fractures.In this paper,the electrical image logs network(EILnet)da deep-learning-based intelligent semantic segmentation model with a selective attention mechanism and selective feature fusion moduledwas created to enable the intelligent identification and segmentation of different types of fractures through electrical logging images.Data from electrical image logs representing structural and induced fractures were first selected using the sliding window technique before image inpainting and data augmentation were implemented for these images to improve the generalizability of the model.Various image-processing tools,including the bilateral filter,Laplace operator,and Gaussian low-pass filter,were also applied to the electrical logging images to generate a multi-attribute dataset to help the model learn the semantic features of the fractures.The results demonstrated that the EILnet model outperforms mainstream deep-learning semantic segmentation models,such as Fully Convolutional Networks(FCN-8s),U-Net,and SegNet,for both the single-channel dataset and the multi-attribute dataset.The EILnet provided significant advantages for the single-channel dataset,and its mean intersection over union(MIoU)and pixel accuracy(PA)were 81.32%and 89.37%,respectively.In the case of the multi-attribute dataset,the identification capability of all models improved to varying degrees,with the EILnet achieving the highest MIoU and PA of 83.43%and 91.11%,respectively.Further,applying the EILnet model to various blind wells demonstrated its ability to provide reliable fracture identification,thereby indicating its promising potential applications.
基金supported by the National Natural Science Foundation of China Joint Fund for Enterprise Innovation and Development,Enrichment Mechanism and Stereoscopic Development of Shale Oil in Continental Rift Basins(No.U24B6002).
文摘Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,the migration behavior of temporary plugging agent(TPA),as a function of the concentration and particle size of TPA and cluster-perforation numbers,etc.,determining the effectiveness of this technique,remains unclear.Therefore,this study conducted innovatively a series of TPDF simulation experiments on transparent polymethyl methacrylate(PMMA)specimens(cubic block of 30 cm×30 cm×30 cm)to explore visually the migration behavior of TPA in multi-clustered HFs in a horizontal well.A laboratory hydraulic sandblasting perforation completion technique was implemented to simulate the multi-cluster perforations.All the distributions of wellbore,perforations,HFs,and TPA can be seen clearly inside the PMMA specimen post the experiment.The results show that there are four characteristic plugging positions for the TPA:mouth of HF,middle of HF,tip of HF,and the intersection of HFs.Small particle size TPA tends to migrate to the fracture tip for plugging,while large particle size TPA tends to plug at the fracture mouth.The migration of the TPA is influenced obviously by the morphology of the fracture wall.A smooth fracture wall is conducive to the migration of the TPA to the far end of HFs,but not conducive to generating the plugging zone and HF diversion.In contrast,a"leaf vein"fracture of rough wall is conducive to generating the plugging layer and the diversion of HFs,but not conducive to the migration of the TPA to the far end of HFs.The migration ability of TPA in a"shell"pattern is intermediate between the two above cases.Increasing TPA concentration can encourage TPA to migrate more quickly to the characteristic plugging position,and thereby to promote the creation of effective plugging and subsequently the multi-stage diversion of the HFs.Nevertheless,excessive concentration may cause the TPA to settle prematurely,affecting the propagation of the HFs to the far end.Increasing the number of clusters to a certain extent can encourage TPA to migrate into the HFs and form plugging,and promote the diversion.An evaluation system for the migration ability of granular TPA has been established,and it was calculated that when there is no plugging expectation target,the comprehensive migration ability of small particle size TPA is stronger than that of large particle size TPA.This research provides theoretical foundation for the optimization of temporary plugging parameters.
基金financially supported by the Hubei Province Education Department of China(Project Name:Research on the Formation Mechanism and Microscopic Characteristics of Tight Dolomite Reservoirs in Salt Lake Basins:A Case Study of the Xingouzui Formation in the Jianghan Basin,Grant No.B2020032).
文摘Shale gas reservoirs typically contain numerous nanoscale pores,with pore size playing a significant role in influencing the gas behavior.To better understand the related mechanisms,this study employs the Gauge-GEMC molecular simulation method to systematically analyze the effects of various pore sizes(5,10,20,and 40 nm)on the phase behavior and dew point pressure of the shale gas reservoir components.The simulation results reveal that when pore sizes are smaller than 40 nm,the dew point pressure increases significantly as the pore size decreases.For instance,the dew point pressure in 5 nmpores is 20.3%higher than undermacroscopic conditions.Additionally,larger hydrocarbon molecules exhibit a tendency to aggregate in smaller pores,particularly in the 5–10 nm range,where the relative concentration of heavy hydrocarbons(C_(4+))increases markedly.Moreover,as the pore size becomes larger,the component distribution gradually aligns with experimental results observed under macroscopic conditions.This study demonstrates that pore effects are more pronounced for smaller sizes,directly influencing the aggregation of heavy hydrocarbons and the rise in dew point pressure.These phenomena could significantly impact the diffusivity of shale gas reservoirs and the recovery of condensate gas.The findings provide new theoretical insights into phase behavior changes in nanopores,offering valuable guidance for optimizing shale gas reservoir extraction strategies.
基金the financial support provide by the National Natural Science Foundation of China(No.52304009)the Natural Science Foundation of Sichuan(No.2023NSFSC0927)the Sichuan Province Innovative Talent Funding Project for Postdoctoral Fellows(No.BX202305)。
文摘Fluid channeling caused by seal failure at the cement sheath-formation interface during fracturing is a severe problem in oil gas wells.In this study,a novel model was developed to evaluate interface sealing integrity.The model's accuracy was verified based on a self-developed interface seal evaluation device and an experiment.Subsequently,the interface seal under different formation conditions was investigated using this model.The theoretical calculation showed that for a cement sheath-carbonate formation interface,the channeling of acid-fracturing fluid caused interface seal failure and sustained casing pressure in the annulus space between the technical casing and formation.Mutual channeling between the fracturing sections occurred at the cement sheathshale formation interface during fracturing.For a sandstone formation,the interface seal failure caused the channeling between a water-bearing formation and a sandstone formation.Aiming at different formation conditions,the mechanical properties requirements of Young's modulus and Poisson's ratio of cement sheath were proposed respectively to ensure its seal integrity.The proposed model and method can be used to evaluate and optimize sealing integrity during fracturing.
基金supported by the National Natural Science Foundation of China(52075214and 51975245)the National Key R&D Program of China(No.2022YFE0138500)+3 种基金Jilin Provincial Science&Technology Department(20220201115GX)Key Science and Technology R&D Projects of Jilin Province(2020C023-3)Program of Jilin University Science and Technology Innovative Research Team(2020TD-03)the Fundamental Research Funds for the Central Universities.
文摘Bipolar plate is one of the key components of Proton Exchange Membrane Fuel Cell(PEMFC)and a reasonable flow field design for bipolar plate will improve cell performance.Herein,we have reviewed conventional and bionic flow field designs in recent literature with a focus on bionic flow fields.In particular,the bionic flow fields are summarized into two types:plant-inspired and animal-inspired.The conventional methodology for flow field design takes more time to find the optimum since it is based on experience and trial-and-error methods.In recent years,machine learning has been used to optimize flow field structures of bipolar plates owing to the advantages of excellent prediction and optimization capability.Artificial Intelligence(AI)-assisted flow field design has been summarized into two categories in this review:single-objective optimization and multi-objective optimization.Furthermore,a Threats-Opportunities-Weaknesses-Strengths(TOWS)analysis has been conducted for AI-assisted flow field design.It has been envisioned that AI can afford a powerful tool to solve the complex problem of bionic flow field design and significantly enhance the performance of PEMFC with bionic flow fields.
文摘Field development practices in many shale gas regions(e.g.,the Changning region)have revealed a persistent issue of suboptimal reserve utilization,particularly in areas where the effective drainage width of production wells is less than half the inter-well spacing(typically 400-500 m).To address this,infill drilling has become a widely adopted and effective strategy for enhancing reservoir contact andmobilizing previously untapped reserves.However,this approach has introduced significant inter-well interference,complicating production dynamics and performance evaluation.The two primary challenges hindering efficient deployment of infill wells are:(1)the quantitative assessment of hydraulic and pressure connectivity between infill wells and their associated parent wells,and(2)the accurate estimation of platform-scale Estimated Ultimate Recovery(EUR)following infill implementation.This study presents a novel framework to quantify inter-well connectivity by deriving a material balance equation tailored for shale gas infill well groups,explicitly incorporating gas adsorption and desorption mechanisms.The model simultaneously evaluates formation pressure evolution and crossflow behavior between wells,offering a robust analytical basis for performance prediction.For infill wells intersecting the drainage boundaries of parent wells,EUR is estimated using an analytical model developed for multi-stage hydraulically fractured horizontal wells.Meanwhile,the EUR of the parent wells is obtained by summing their pre-infill EUR with the final inter-well crossflow contribution.
文摘The ocean,as one of Earth’s largest natural resources,covers over 70% of the planet’s surface and holds vast water energy potential.Building on this context,this study designs a hybrid generator(WWR-TENG)that integrates a triboelectric nanogenerator(TENG)and an electromagnetic generator(EMG).TENG is a new technology that can capture mechanical energy from the environment and convert it into electrical energy,and is particularly suitable for common natural or man-made power sources such as human movement,wind power,and water flow.EMG is a device that converts mechanical energy into electrical energy through the principle of electromagnetic induction and can usually provide stable power output.The composite design leverages the complementary advantages of both technologies to efficiently capture and convert marine wave energy.By combining the TENG’s high energy conversion efficiency,lowcost,lightweight structure,and simple designwith the EMG’s capabilities,the systemprovides a sustainable solution for marine energy development.Experimental results demonstrate that at a rotational speed of 3.0 r/s,the TENG component of the WWR-TENG achieves an open-circuit voltage of approximately 280 V and a shortcircuit current of 20μA.At the same time,the EMG unit exhibits an open-circuit voltage of 14 V and a short-circuit current of 14 mA.Furthermore,when integrated with a power management circuit,the WWR-TENG charges a 680μF capacitor to 3 V within 10 s at a rotational speed of 3.0 r/s.A simulated wave environment platform was established,enabling the WWR-TENG to maintain the thermo-hygrometer in normal operation under simulated wave conditions.These findings validate the hybrid system’s effectiveness in harnessing and storingwave energy,highlighting its potential for practical marine energy applications.
基金Research Project of Lianyungang Association for Science and Technology(Lkxyb1907)Research Project of"333 Project"of Jiangsu Province(BRA2019245)Research Project of"521"Project of Lianyungang City(LYG52105-2018090)。
文摘Assessment of water quality by firefly algorithm based on BP neural network model(FA-BP model)is built.In this model,the evaluation index function is constructed by BP Artificial Neural Network Algorithm(BP model),and Firefly Algorithm(FA model)is introduced to optimize weight values and thresholds to find the optimal solution.Fuzzy Comprehensive Evaluation method,Grey Incidence Analysis Algorithm and FA-BP model will be applied to evaluate the water quality of the five main rivers in Lianyungang City including Longwei,Yudai,Dapu,Paidan,and Dongyan River.The results show that the Fuzzy Comprehensive Evaluation method is difficult to use for slight pollution rivers with several slightly over standard indexes.It will be easy to ignore the impact of extreme indexes by Grey Incidence Analysis Algorithm.FA-BP model solves the shortcomings of the two methods.The evaluation results provide an important reference for the formulation of reasonable measures.It is a relatively comprehensive evaluation method and has a good application prospect in water quality evaluation.
基金jointly supported by the National Natural Science Foundation of China[51671201,51971230]the National Science and Technology Major Project[2017ZX06002003-004-002]the Key Programs of the Chinese Academy of Sciences[Research on the Development of Nuclear Power Materials and Service Security Technology,ZDRW-CN-2017-1]。
文摘The uniform corrosion behavior of model FeCrAl alloys as well as commercial Zircaloy-4 as reference material were investigated in 360℃borated and lithiated water.The results reveal that FeCrAl alloys exhibited better corrosion resistance than Zircaloy-4.It is found that the oxide films formed on the FeCrAl alloys are composed of outer Fe_(3)O_(4)layer,inner layer consisting of compact spinel layer and porous spinel layer,and transition layer containing Al-Cr-rich oxides and matrix enriched with Fe°.The spinel oxides in the inner layer are FeFe_(2-x-y-z)Cr_(x)Al_(y)MozO_(4).The corrosion mechanism of FeCrAl alloys in high temperature water is discussed.
基金Supported by the National Natural Science Foundation of China(51974332).
文摘This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion with multi-cluster sand jetting perforation.The effects of temporary plugging agent(TPA)particle size,TPA concentration,single-cluster perforation number and cluster number on plugging pressure,multi-fracture diversion pattern and distribution of TPAs were investigated.A combination of TPAs with small particle sizes within the fracture and large particle sizes within the segment is conducive to increasing the plugging pressure and promoting the diversion of multi-fractures.The addition of fibers can quickly achieve ultra-high pressure,but it may lead to longitudinal fractures extending along the wellbore.The temporary plugging peak pressure increases with an increase in the concentration of the TPA,reaching a peak at a certain concentration,and further increases do not significantly improve the temporary plugging peak pressure.The breaking pressure and temporary plugging peak pressure show a decreasing trend with an increase in single-cluster perforation number.A lower number of single-cluster perforations is beneficial for increasing the breaking pressure and temporary plugging peak pressure,and it has a more significant control on the propagation of multi-cluster fractures.A lower number of clusters is not conducive to increasing the total number and complexity of artificial fractures,while a higher number of clusters makes it difficult to achieve effective plugging.The TPAs within the fracture is mainly concentrated in the complex fracture areas,especially at the intersections of fractures.Meanwhile,the TPAs within the segment are primarily distributed near the perforation cluster apertures which initiated complex fractures.
基金Supported by the Fundamental Project of China National Petroleum Corporation(2021DJ0501).
文摘The relationship between paleogeographic pattern and sedimentary differentiation of evaporite-carbonate symbiotic system is examined based on logging,core and thin section data,by taking the sixth sub-member of fifth member of Ordovician Majiagou Formation(M56)in the central-eastern Ordos Basin as an example.(1)Seven sub-geomorphic units(Taolimiao west low,Taolimiao underwater high,Taolimiao east low,Hengshan high,East salt low,North slope and Southwest slope)developed in the study area.(2)The“three lows”from west to east developed dolomitic restricted lagoon,evaporite evaporative lagoon and salt evaporative lagoon sedimentary facies respectively,the"two highs"developed high-energy grain beach and microbial mound,and the north and south slopes developed dolomitic flats around land.(3)The paleogeographic pattern caused natural differentiation of replenishment seawater from the northwest Qilian sea,leading to the eccentric sedimentary differentiation of dolomite,evaporite and salt rock symbiotic system from west to east,which is different from the classic“bull's eye”and“tear drop”distribution patterns.(4)As the Middle Qilian block subducted and collided into the North China Plate,the far-end compression stress transferred,giving rise to the alternate highland and lowland in near north to south direction during the sedimentary period of M56 sub-member.(5)Taolimiao underwater high and Hengshan high developed favorable zones of microbial mounds and grain shoals in south to north strike in M56 sub-member,making them favorable exploration areas with great exploration potential in the future.
基金Supported by National Natural Science Foundation of China(51904258,51874250)Project of Science and Technology of Shale Gas Exploration&Development of CCDC(2019-JS-941)National Major Project of Science and Technology(2016ZX05048-004-006)。
文摘To study the casing deformation(CD)in shale gas well fracturing caused by natural fracture slip,a fracture face stress model is built based on stress analysis,and a CD prediction model is established based on complex function to analyze factors affecting wellbore shear stress and CD.(1)The fracture and wellbore approach angles have significant impacts on the wellbore shear stress.In Weiyuan shale gas field,Sichuan Basin,under the common wellbore approach angle of nearly 90°,the wellbore is subjected to large shear stress and high risk of CD at the fracture approach angle range of 20° to 55° or its supplementary angle range.(2)When the fracture is partially opened,the wellbore shear stress is positively correlated with the fluid pressure,and negatively correlated with the fracture friction coefficient;when the fracture is fully opened,the wellbore shear stress is positively correlated with the natural fracture area.(3)The lower the elastic modulus and the longer the fracture length,the more serious the CD will be,and the Poisson’s ratio has a weak influence on the CD.The deformation first increases and then decreases with the increase of fracture approach angle,and reaches the maximum when the fracture approach angle is 45°.(4)At a given fracture approach angle,appropriately adjusting the wellbore approach angle can avoid high shear stress acting on wellbore,and reasonable control of the fluid pressure in the fracture can reduce the CD risk.The shear stress acting on casing is usually much greater than the shear strength of casing,so increasing casing strength or cementing quality have limited effect on reducing the risk of CD.Caliper logging data has verified that the CD prediction model is reliable,so the model can be used to establish risk analysis chart and calculate deformation value,to provide a reference for quick CD risk prediction in fracturing design.
基金Project(51674212)supported by the National Natural Science Foundation of China。
文摘Pencil hardness testing,electrochemical impedance spectroscopy,scanning electron microscopy,and scanning Kelvin probe microscopy were used to study the local corrosion characteristics of a graphene-oxide-modified inner coating.The effect of chloride concentration on the corrosion of the damaged inner coating was studied.The effects of chloride ions on damaged internal coatings and graphene-oxide-modified internal coatings were investigated.It was proposed to add graphene oxide into the epoxy coating to effectively inhibit the metal corrosion at the breakage.Because of the existence of graphene oxide(GO),the modified coating had a better physical property and had the effective infiltration of H2O and Cl^- into the coating.The results showed that graphene oxide coatings can give X80 steel better corrosion resistance in sodium chloride solution.
文摘According to the blasting construction of the diaphragm wall of Puxi approaching section of East Fuxing Road river-crossing tunnel, the monitoring project of the vibration of the existing tun-nel induced by the blasting construction is put forward, which includes the sensors’ location, moni-tor method and the vibration monitoring system. Based on the monitoring data of the explosion vibration, the vibration wave forms, velocities, acceleration responses, main frequencies and fields of measure points are analyzed under the conditions of three locations and different charge quanti-ties. According to the safety-judging standard of explosion vibration, the conclusion that the exist- ing tunnel is safe under the explosion vibration is then drawn. Furthermore, the spectrum character-istics of three explosion vibrations and the spectrum changing properties of explosion vi-bration wave transmitting in different directions are concluded, which can provide reference to similar projects.
基金supported by the China-WHO Biennial Collaborative Projects 2016–2017(No.2016/648722–0).
文摘BACKGROUND Catheter ablation for atrial fibrillation(AF)is commonly performed worldwide.However,the clinical charac-teristics of hospitalized patients with AF and national trends in catheter ablation at tertiary hospitals in China remain unreported.METHODS This study used the Chinese national database(Hospital Quality Monitoring System)from 2013 to 2016,which is a mandatory database that collects the front page of patients’medical records for hospital accreditation,to describe the clinical cha-racteristics of patients with AF as an overall cohort and as subgroups divided by catheter ablation and sex.RESULTS Of 597,919 AF patients first admitted,57,983 patients underwent catheter ablation[56,384 cases(97.2%)of radiofre-quency ablation and 1599 cases(2.8%)of cryoablation]at 746 tertiary hospitals.Nearly 10%of patients hospitalized with AF at ter-tiary hospitals in China underwent catheter ablation,and the percentage of patients undergoing catheter ablation was on the rise bet-ween 2013 and 2016,and the number of cases increased by 2.5 times.Compared with AF patients who did not undergo catheter ablation,those who did were younger,more frequently male,and had fewer baseline comorbidities.Although the overall CHA_(2)DS_(2)-VASc score revealed over half of the patients were high-risk,patients who underwent catheter ablation were mostly low-risk(71.2%of males and 59.1%of females).Considering in-hospital adverse events,the overall pericardial tamponade and all-cause death incidences were 0.2%(0.6%in the ablation group)and 1.2%(0.1%in the ablation group),respectively;both of which were higher in females than males.CONCLUSIONS In this study,AF patients who underwent catheter ablation were relatively young,had a low thrombosis risk,and had few comorbidities and adverse events.Females were older and experienced more complications than males.
文摘Long-term kinematic research of slow- moving debris slide is rare despite of the widespread global distribution of this kind. This paper presents a study of the kinematics and mechanism of the Jinpingzi debris slide located on the Jinsha river bank in southwest China. This debris slide is known to have a volume of 27×106 ms in active state for at least one century. Field survey and geotechnical investigation were carried out to define the structure of the landslide. The physical and mechanical properties of the landslide materials were obtained by in-situ and laboratory tests. Additionally, surface and subsurface displacements, as well as groundwater level fluctuations, were monitored since 2005. Movement features, especially the response of the landslide movement to rainfall, were analysed. Relationships between resisting forces and driving forces were analysed by using the limit equilibrium method assuming rigid-plastic frictional slip. The results confirmed a viscous comoonent in the long-term continuous movement resulting in the quasioverconsolidated state of the slip zone with higher strength parameters than some other types of slowmoving landslides. Both surface and subsurface displacements showed an advancing pattern by the straight outwardly inclined （rather than gently or reversely inclined） slip zone, which resulted in low resistance to the entire sliding mass. The average surface displacement rate from 2005 to 2016 was estimated to be 0.19-0.87 mm/d. Basal sliding on the silty clay seam accounted for most of the deformation with different degrees of internal deformation in different parts. Rainfall was the predominant factor affecting the kinematics of Jinpingzi landslide while the role of groundwater level, though positive, was not significant. The response of the groundwater level to rainfall infiltration was not apparent. Unlike some shallow slow-moving earth flows or mudslides, whose behaviors are directly related to the phreatic groundwater level, the mechanism for Jinpingzi landslide kinematics is more likely related to the changing weight of the sliding mass and the downslope seepage pressure in the shallow soil mass resulting from rainfall events.
文摘Thermoelectric generators(TEGs)are considered promising devices for waste heat recovery from various systems.The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer receiver(FDR)of an air conditioning(A/C)system,which would otherwise go to waste.The study aims to build a set of thermoelectric generators(TEG)to collect the waste heat of the FDR and generate low-power electricity.A novel electrical circuit with two transformers is designed and fabricated to produce a more stable voltage for operation and charging.The thermoelectric generator(TEGs)was installed on the FDR of the A/C unit.The test showed that climate conditions have a significant impact on the output power generated from the system.The results showed that the peak voltage recorded in the current study is 5.2 V per day(wet,cold,and wind weather)with an output power of 0.2 W.These values are acceptable for powering the load and charging a single battery with 3.5 V as the voltage increases battery 0.1 V/20 min charge.A case study of operating the emergency signs in a building was considered.The current heat recovery system is deemed to be easily installed and can be connected to a network of TEGs to produce more power.
