During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and proper...During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and properly evaluate air tightness of polymer sealing caverns,the air-pressure-related air density and permeability must be considered.In this context,the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation.The air tightness model of compressed air storage energy caverns is then established.In the model,the permeability coefficient and air density of sealing layer vary with air pressure,and the effectiveness of the model is verified by field data in two test caverns.Finally,a compressed air storage energy cavern is taken as an example to understand the air tightness.The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density,which is constant and small in the previous leakage rate calculation.Under the operating pressure of 4.5-10 MPa,the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%,which can meet the sealing requirements of compressed air storage energy caverns.The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure,injected air temperature,cavern radius,and sealing layer thickness.The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature,or the cavern radius and sealing layer thickness will be increased.展开更多
The objective of this investigation was to study whether it is possible to determine the air tightness of covered slurry storage tanks using tracer gas technique by injection of sulphur hexafluoride （SF6） and measur...The objective of this investigation was to study whether it is possible to determine the air tightness of covered slurry storage tanks using tracer gas technique by injection of sulphur hexafluoride （SF6） and measurements of the decay in gas concentrations with an infrared spectrophotometer in the air space above the slurry. By measuring the decay in concentration of injected tracer gas at different occasions, the air exchange rate was determined. Three different types of coverings were studied namely; wooden roof, plastic tent and concrete roof.展开更多
In the railway system,fasteners have the functions of damping,maintaining the track distance,and adjusting the track level.Therefore,routine maintenance and inspection of fasteners are important to ensure the safe ope...In the railway system,fasteners have the functions of damping,maintaining the track distance,and adjusting the track level.Therefore,routine maintenance and inspection of fasteners are important to ensure the safe operation of track lines.Currently,assessment methods for fastener tightness include manual observation,acoustic wave detection,and image detection.There are limitations such as low accuracy and efficiency,easy interference and misjudgment,and a lack of accurate,stable,and fast detection methods.Aiming at the small deformation characteristics and large elastic change of fasteners from full loosening to full tightening,this study proposes high-precision surface-structured light technology for fastener detection and fastener deformation feature extraction based on the center-line projection distance and a fastener tightness regression method based on neural networks.First,the method uses a 3D camera to obtain a fastener point cloud and then segments the elastic rod area based on the iterative closest point algorithm registration.Principal component analysis is used to calculate the normal vector of the segmented elastic rod surface and extract the point on the centerline of the elastic rod.The point is projected onto the upper surface of the bolt to calculate the projection distance.Subsequently,the mapping relationship between the projection distance sequence and fastener tightness is established,and the influence of each parameter on the fastener tightness prediction is analyzed.Finally,by setting up a fastener detection scene in the track experimental base,collecting data,and completing the algorithm verification,the results showed that the deviation between the fastener tightness regression value obtained after the algorithm processing and the actual measured value RMSE was 0.2196 mm,which significantly improved the effect compared with other tightness detection methods,and realized an effective fastener tightness regression.展开更多
When a cold rolled strip is being treated in a continuous annealing furnace which is full of protective gas, the gas tightness of the furnace body, the connected facilities and the gas channels become an important ind...When a cold rolled strip is being treated in a continuous annealing furnace which is full of protective gas, the gas tightness of the furnace body, the connected facilities and the gas channels become an important indicator that directly affects the product＇s surface quality and shows the technical level of the design, the manufacture and the installation. By considering the problems of the gas tightness of a vertical annealing furnace in the installation and maintenance, this thesis evaluates the gas tightness indicator and gas tightness related level of the furnace body and the circulation duct, while studying and analyzing the technologies of negative-pressure leak detection and sealing.展开更多
Since the tubeless tires and especially cast alloy wheels are used, the air tightness of wheels is an important factor of the automobiles quality. Based on specification of the car industry that up to 10% decrease of ...Since the tubeless tires and especially cast alloy wheels are used, the air tightness of wheels is an important factor of the automobiles quality. Based on specification of the car industry that up to 10% decrease of the prescribed nominal tire pressure during a time of six-month is allowed, the requirements presented in specifications and norms are treated and validated. The practical experience and influences on the wheel tightness control are discussed and the data presented in a report of a wheel manufacturer, concerning the replacements of wheels in service due to air leakage are evaluated. Summarizing the results of analyses, a proposal is made for the testing of the cast aluminum car wheels to meet the requirements for a reliable and economical air tightness control in modern test facilities.展开更多
In this paper, we discuss tightness and fan tightness of multifunction spaces with pointwise convergence topology or compact-open topology, and generalize some results on con- tinuous single-valued function spaces to ...In this paper, we discuss tightness and fan tightness of multifunction spaces with pointwise convergence topology or compact-open topology, and generalize some results on con- tinuous single-valued function spaces to continuous multifunction spaces.展开更多
In recent years,“cultural tightness-looseness”refers to the strength of social norms and tolerance for deviant behaviors perceived by individuals in society,and team cultural tightness applied at the organizational ...In recent years,“cultural tightness-looseness”refers to the strength of social norms and tolerance for deviant behaviors perceived by individuals in society,and team cultural tightness applied at the organizational level represents the strength of team norms.According to the cultural tightness-looseness theory,this study explores the influence of team cultural tightness on employee creative behavior,as well as the moderating role of transformational leadership and the mediating role of work engagement.A questionnaire method was used to survey five enterprise organizations in China through three stages,and 288 paired questionnaires were finally obtained from leaders and employees.The results found that team cultural tightness has a significant negative effect on employee creative behavior through the mediating effect of work engagement.In other words,the more the team culture in the workplace tends to be loose,the more it stimulates employee work engagement,which in turn promotes employee creative behavior.In addition,transformational leadership played a significant positive moderating role in the model.Under the influence of transformational leadership style,the negative impact of team cultural tightness on employee work engagement and creative behavior can be mitigated.The study enriches the understanding of the influence and action mechanism of the cultural tightness-looseness theory on employee creative behavior.In future research,the action mechanism of team cultural tightness interacting with different leadership styles to influence employee creative behavior will be explored more deeply.展开更多
In this paper, we discuss the countable tightness of products of spaces which are quotient simages of locally separable metric spaces, or k-spaces with a star-countable k-network. The main result is that the following...In this paper, we discuss the countable tightness of products of spaces which are quotient simages of locally separable metric spaces, or k-spaces with a star-countable k-network. The main result is that the following conditions are equivalent： （1） b = ω1; （2） t（Sω×Sω1） 〉 ω; （3） For any pair （X, Y）, which are k-spaces with a point-countable k-network consisting of cosmic subspaces, t（X×Y）≤ω if and only if one of X, Y is first countable or both X, Y are locally cosmic spaces. Many results on the k-space property of products of spaces with certain k-networks could be deduced from the above theorem.展开更多
Injecting impure CO_(2)for enhanced gas recovery(CO_(2)-EGR)offers a dual benefit by improving natural gas extraction while enabling CO_(2)sequestration.However,the interactions between CO_(2),N_(2),and CH_(4)under re...Injecting impure CO_(2)for enhanced gas recovery(CO_(2)-EGR)offers a dual benefit by improving natural gas extraction while enabling CO_(2)sequestration.However,the interactions between CO_(2),N_(2),and CH_(4)under reservoir conditions require further investigation.This study employs Grand Canonical Monte Carlo(GCMC)and Molecular Dynamics(MD)simulations to quantify the adsorption and diffusion behaviors of CO_(2),N_(2),and CH_(4)in quartz nanopores over a pressure range of 1-24 MPa under varying water saturations and gas compositions.The results indicate that:(1)CO_(2)exhibits the broadest energy distribution and the strongest adsorption stability,occupying about 20%-30%more adsorption sites than CH_(4)or N_(2)and showing the least sensitivity to water saturation,with only a 30%reduction at 50%saturation,compared to 60%for CH_(4),giving CO_(2)a clear competitive advantage.(2)The adsorption and desorption behaviors are strongly pressure dependent,as increasing pressure reduces the adsorption layer area and shifts gas distribution from adsorption dominated to free phase.Competitive adsorption analysis reveals that while CO_(2)dominates displacement at low pressures,mixtures that contain N_(2)achieve higher CH_(4)desorption efficiency above 13 MPa by mitigating diffusion resistance.(3)A higher N_(2)fraction improves CH_(4)diffusion coefficients,thereby facilitating gas mobility and ensuring superior recovery performance under high-pressure conditions.This study advances the fundamental knowledge of microscale gas behavior in tight sandstones and supports the feasibility of impure CO_(2)injection as a practical strategy for sustainable gas production.展开更多
Re-fracturing horizontal wells is a critical strategy for enhancing recovery from tight oil reservoirs,but its success depends on the evaluation of candidate wells and locations.This process is complicated by producti...Re-fracturing horizontal wells is a critical strategy for enhancing recovery from tight oil reservoirs,but its success depends on the evaluation of candidate wells and locations.This process is complicated by production-induced alterations in reservoir pressure and geomechanical responses.This study introduces a workflow to evaluate re-fracturing potential by integrating coupled fluid flow and geomechanical modeling for the production of initial hydraulic fractures.We developed a numerical model that simulates the poroelastic response of a tight oil reservoir to depletion from an initial set of hydraulic fractures.To quantify the re-fracturing potential along the horizontal wellbore,a novel composite re-fracturing potential index is proposed where fracture shape,stress,and pressure are considered.This index considers four key physical factors:current reservoir pressure,fracture initiation ease,fracture geometry favorability,and fracture propagation efficiency considering tortuosity.Numerical simulations were conducted for scenarios with both uniform and non-uniform initial hydraulic fractures.The results consistently demonstrate that the optimal locations for re-fracturing are the midpoints between existing fractures,where a favorable balance of high reservoir pressure and altered stress conditions exists.The analysis reveals that the overall re-fracturing potential tends to increase with production time,suggesting that a period of depletion can enhance the geomechanical conditions for subsequent stimulation.Furthermore,a sensitivity analysis on the index weighting factors shows that the optimum re-fracturing strategy is highly dependent on the primary field objective,whether it is maximizing resource contact,ensuring geomechanical feasibility,or avoiding operational complexity.The study concludes that heterogeneity in the initial fracture network creates complex and asymmetric potential profiles,which implies the necessity of case-specific and integrated analysis over simplified assumptions.The proposed methodology provides a framework for optimizing re-fracturing designs in tight oil reservoirs.展开更多
Gastric cancer(GC)is the fifth most prevalent malignancy worldwide and remains a leading cause of cancer-related mortality.Major risk factors for GC include Helicobacter pylori infection,increasing age,high dietary sa...Gastric cancer(GC)is the fifth most prevalent malignancy worldwide and remains a leading cause of cancer-related mortality.Major risk factors for GC include Helicobacter pylori infection,increasing age,high dietary salt intake,and diets deficient in vegetables and fruits.Due to the often subtle and nonspecific early symptoms,coupled with the lack of routine screening programs,a significant proportion of GC cases are diagnosed at advanced stages.The etiology of GC is multifactorial,and diagnosis is confirmed histologically through endoscopic biopsy,followed by staging via computed tomography,positron emission tomography,staging laparoscopy,and endoscopic ultrasound.Treatment strategies typically involve a multidisciplinary approach including chemotherapy,surgical resection,radiotherapy,and emerging immunotherapeutic options.Despite advances in diagnostic and therapeutic modalities,the prognosis of advanced GC remains poor,with high rates of recurrence and metastasis.In recent years,increasing attention has been given to the role of tight junction(TJ)proteins in the pathogenesis and progression of GC.TJ proteins,critical components of epithelial barrier function,have been implicated in various stages of gastric carcinogenesis,from intestinal metaplasia to invasion and metastasis.Infection and inflammation,particularly due to Helicobacter pylori,disrupt TJ integrity,compromising the gastric mucosal barrier and facilitating neoplastic transformation.This review synthesizes current evidence from PubMed,EMBASE,Google Scholar,ScienceDirect,SpringerLink,and other reputable databases to provide a comprehensive overview of the involvement of TJ proteins in GC.By elucidating the molecular interplay between TJ dysregulation and gastric tumorigenesis,this work aims to highlight the potential of TJ proteins as novel diagnostic biomarkers and therapeutic targets in GC management.展开更多
Methods of quantum information processing often appear in terms of specially selected states.For example,mutually unbiased bases(MUBs)and symmetric informationally complete measurements are widely applied.Finite frame...Methods of quantum information processing often appear in terms of specially selected states.For example,mutually unbiased bases(MUBs)and symmetric informationally complete measurements are widely applied.Finite frames have found use in many areas including quantum information.Due to its specific inner structure,a single equiangular tight frame(ETF)allows one to formulate criteria to detect non-classical correlations.This study aims to approach entanglement detection with the use of mutually unbiased ETFs.Such frames are an interesting generalization of widely recognized MUBs.It still uses rank-one operators,but the number of outcomes can exceed the dimensionality.Several approaches are considered including separability criteria and entanglement witnesses.Separability criteria for multipartite systems are finally obtained.展开更多
The blood-spinal cord barrier is crucial for preserving homeostasis of the central nervous system.After spinal cord injury,autophagic flux within endothelial cells is disrupted,compromising the integrity of the blood-...The blood-spinal cord barrier is crucial for preserving homeostasis of the central nervous system.After spinal cord injury,autophagic flux within endothelial cells is disrupted,compromising the integrity of the blood-spinal cord barrier.This disruption facilitates extensive infiltration of inflammatory cells,resulting in exacerbated neuroinflammatory responses,neuronal death,and impaired neuronal regeneration.Previous research has demonstrated that photobiomodulation promotes the regeneration of damaged nerves following spinal cord injury by inhibiting the recruitment of inflammatory cells to the injured site and restoring neuronal mitochondrial function.However,the precise mechanisms by which photobiomodulation regulates neuroinflammation remain incompletely elucidated.In this study,we established a mouse model of spinal cord injury and assessed the effects of photobiomodulation treatment.Photobiomodulation effectively cleared damaged mitochondria from endothelial cells in mice,promoting recovery of hindlimb motor function.Using microvascular endothelial bEnd.3 cells subjected to oxygen-glucose deprivation,we found that the effects of photobiomodulation were mediated through activation of the PINK1/Parkin pathway.Additionally,photobiomodulation reduced mitochondrial oxidative stress levels and increased the expression of tight junction proteins within the blood-spinal cord barrier.Our findings suggest that photobiomodulation activates mitochondrial autophagy in endothelial cells through the PINK1/Parkin pathway,thereby promoting repair of the blood-spinal cord barrier following spinal cord injury.展开更多
The concurrent exploration of shale oil wells in the Gulong Sag of the Songliao Basin has uncovered promising hydrocarbon shows in the Fuyu pay zone of the Lower Cretaceous Quantou Formation.To assess the hydrocarbon ...The concurrent exploration of shale oil wells in the Gulong Sag of the Songliao Basin has uncovered promising hydrocarbon shows in the Fuyu pay zone of the Lower Cretaceous Quantou Formation.To assess the hydrocarbon exploration potential of the Fuyu pay zone,this study systematically analyzes the main controlling factors for hydrocarbon accumulation,including source rock conditions,reservoir characteristics and migration capacity,in the deep area of the Gulong Sag,using seismic,drilling and core data,and reveals the hydrocarbon enrichment mechanism and accumulation model.The results indicate that the source rocks in the first member of Cretaceous Qingshankou Formation(Qing-1 Member)in the Gulong Sag are widely distributed,characterized by high quality,large area,high maturity and high hydrocarbon generation intensity,providing an ample oil source for the Fuyu pay zone.The Fuyu pay zone in the Gulong Sag features multi-phase channel sand bodies and beach-bar sands that are laterally superimposed and vertically stacked,forming large-scale sand-rich reservoir assemblages,which provide the storage space for tight oil enrichment.Influenced by overpressure pore preservation and dissolution-enhanced porosity,the porosity of the Fuyu pay zone can reach up to 13%,meeting the reservoir conditions necessary for large-scale tight oil enrichment.The episodic opening of hydrocarbon-source connected faults during the hydrocarbon expulsion period,combined with source-reservoir pressure differentials,drives the efficient charging and enrichment of hydrocarbons into the underlying tight reservoirs.The hydrocarbon accumulation model of the Fuyu pay zone is summarized as“source-reservoir juxtaposition,overpressure charging,lateral source-reservoir connection+vertical fault-directed bidirectional hydrocarbon supply,continuous sand body distribution,and large-scale enrichment in fault-horst belts”.A new insight for the deep area of the Gulong Sag is proposed as being sand-rich,having superior reservoirs,and being oil-rich.This insight guided the deployment of three risk exploration wells.The Well HT1H achieved a high-yield industrial oil flow rate of 35.27 t/d during testing,discovering light tight oil with low density and low viscosity.Through horizontal well volumetric fracturing treatment,the Well HT1H achieved the first high-yield breakthrough of tight oil in the deep area of the Gulong Sag,confirming the presence of geological conditions for large-scale hydrocarbon accumulation in this area.This expands the potential for hundred-million-ton tight oil resource additions in the Songliao Basin and deepens the theoretical understanding of continental tight oil accumulation.展开更多
Electron–hole(e–h)recombination is a fundamental process that governs energy dissipation and device efficiency in semiconductors.In two-dimensional(2D)materials,the formation of tightly bound excitons makes exciton-...Electron–hole(e–h)recombination is a fundamental process that governs energy dissipation and device efficiency in semiconductors.In two-dimensional(2D)materials,the formation of tightly bound excitons makes exciton-mediated e–h recombination the dominant decay pathway.In this work,nonradiative e–h recombination within excitons in monolayer MoS_(2) is investigated using first-principles simulations that combine nonadiabatic molecular dynamics with GW and real-time Bethe–Salpeter equation(BSE)propagation.A two-step process is identified:rapid intervalley redistribution induced by exchange interaction,followed by slower phonon-assisted recombination facilitated by exciton binding.By selectively removing the screened Coulomb and exchange terms from the BSE Hamiltonian,their respective contributions are disentangled—exchange interaction is found to increase the number of accessible recombination pathways,while binding reduces the excitation energy and enhances nonradiative decay.A reduction in recombination lifetime by over an order of magnitude is observed due to the excitonic many-body effects.These findings provide microscopic insights for understanding and tuning exciton lifetimes in 2D transition-metal dichalcogenides.展开更多
As an emerging rock-breaking technology,microwave irradiation has demonstrated significant potential as an auxiliary technique for volume stimulation in hydraulic fracturing.This study focuses on tight sandstone gas e...As an emerging rock-breaking technology,microwave irradiation has demonstrated significant potential as an auxiliary technique for volume stimulation in hydraulic fracturing.This study focuses on tight sandstone gas extraction,introducing a hollow double-wing crack(HDWC)configuration into the research on tight sandstone.Laboratory experiments were conducted to investigate microwave-induced fracturing mechanisms and the mechanical behavior of HDWC-containing sandstone,aiming to elucidate the thermal cracking patterns and underlying mechanisms under microwave irradiation conditions.To further explore the electromagnetic-thermal-mechanical(E-T-M)interactions in tight sandstone under microwave treatment,a coupled finite element method(FEM)-discrete element method(DEM)numerical model was developed.This model enabled a detailed analysis of force chain evolution and microcrack propagation within HDWC-containing sandstone.Additionally,preliminary hydraulic fracturing simulations were performed to investigate fracture initiation pressure and fracture evolution following microwave exposure.The main findings of this study are as follows:(1)Microwave heating induces thermal cracks at both the tips and midsections of the HDWC.Microwave irradiation degrades the mechanical properties of HDWC-containing sandstone.(2)Simulation results reveal that significant stress concentration and tensile-compressive zoning occur near the HDWC under microwave irradiation.Microcrack development exhibits an avalanche effect.(3)Hydraulic fracturing simulations indicate that microwave heating generally promotes hydraulic fracture generation.Microwave irradiation reduces the fracture initiation pressure and enhances the complexity and connectivity of the fracture network.These findings provide valuable insights into the application of microwave-assisted volume stimulation as a supporting technology for hydraulic fracturing in deep reservoirs.展开更多
To address the persistent challenge of dynamic mismatch between wellbore lifting capacity and reservoir fluid supply,and to establish a robust optimization framework for drainage operations in high-water-cut tight san...To address the persistent challenge of dynamic mismatch between wellbore lifting capacity and reservoir fluid supply,and to establish a robust optimization framework for drainage operations in high-water-cut tight sandstone gas reservoirs,this study systematically investigates the graded optimization and dynamic adaptation of drainage gas recovery technologies.Production data from a representative tight gas field were first employed to forecast reservoir performance.The predictive reliability was rigorously validated through high-precision history matching,thereby providing a quantitatively consistent foundation for subsequent wellbore optimization.Building on this characterization,a coupled simulation framework was developed that integrates wellbore multiphase flow modeling with nodal analysis based on the Inflow Performance Relationship,IPR,and the Vertical Lift Performance,VLP.This coordinated approach enables comprehensive evaluation of process adaptability and dynamic optimization of foam-assisted drainage,mechanical pumping,and jet pumping systems under evolving water-gas ratio,WGR conditions.The results reveal that a progressively increasing water-gas ratio is the dominant factor driving the transition from chemically assisted drainage methods to mechanically enhanced lifting technologies.A distinct quantitative threshold is identified at WGR≈0.002,beyond which mechanical intervention becomes more effective and economically justified.For mechanical pumping and jet pumping systems,a parameter inversion optimization strategy constrained by the target bottomhole flowing pressure,Pwf,is proposed to ensure stable production while maintaining reservoir drawdown control.In particular,the nozzle-to-throat area ratio of the jet pump is identified as the key governing parameter influencing entrainment capacity and lifting efficiency.Moreover,a configuration characterized by small pump diameter,long stroke length,and low operating speed is demonstrated to satisfy drainage requirements while mitigating torque fluctuations,enhancing volumetric efficiency,and improving pump fillage stability.展开更多
The effective channeling of fluid flow by fractures is a liability for enhanced oil recovery(EOR)methods like CO_(2) flooding or CO_(2) storage.Developing a distributed fracture model to understand the heterogeneity o...The effective channeling of fluid flow by fractures is a liability for enhanced oil recovery(EOR)methods like CO_(2) flooding or CO_(2) storage.Developing a distributed fracture model to understand the heterogeneity of the fracture network is essential in characterizing tight and low-permeability reservoirs.In the Ordos Basin,the Chang 8-1-2 layer of the Yanchang Formation is a typical tight and low permeability reservoir in the JH17 wellblock.The strong heterogeneity of distributed fractures,differing fracture scales and fracture types make it difficult to effectively characterize the fracture distribution within the Chang 8-1-2 layer.In this paper,multi-source and multi-attribute methods are used to integrate data into a neural network at different scales,and fuzzy logic control is used to judge the correlation of various attributes.The results suggest that attribute correlation between coherence and fracture indication is the best,followed by correlations with fault distance,north–south slope,and north–south curvature.Advantageous attributes from the target area are used to train the neural network,and the fracture density model and discrete fracture network(DFN)model are built at different scales.This method can be used to effectively predict the distribution characteristics of fractures in the study area.And any learning done by the neural network from this case study can be applied to fracture network modeling for reservoirs of the same type.展开更多
基金We acknowledge the funding support from the National Science Foundation of China(Grant No.52278402)the Young Scientist Project of the National Key Research and Development Program of China(Grant No.2021YFC2900600)the Fundamental Research Funds for the Central Universities of China(Grant No.22120220117).
文摘During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and properly evaluate air tightness of polymer sealing caverns,the air-pressure-related air density and permeability must be considered.In this context,the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation.The air tightness model of compressed air storage energy caverns is then established.In the model,the permeability coefficient and air density of sealing layer vary with air pressure,and the effectiveness of the model is verified by field data in two test caverns.Finally,a compressed air storage energy cavern is taken as an example to understand the air tightness.The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density,which is constant and small in the previous leakage rate calculation.Under the operating pressure of 4.5-10 MPa,the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%,which can meet the sealing requirements of compressed air storage energy caverns.The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure,injected air temperature,cavern radius,and sealing layer thickness.The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature,or the cavern radius and sealing layer thickness will be increased.
文摘The objective of this investigation was to study whether it is possible to determine the air tightness of covered slurry storage tanks using tracer gas technique by injection of sulphur hexafluoride （SF6） and measurements of the decay in gas concentrations with an infrared spectrophotometer in the air space above the slurry. By measuring the decay in concentration of injected tracer gas at different occasions, the air exchange rate was determined. Three different types of coverings were studied namely; wooden roof, plastic tent and concrete roof.
基金Supported by Fundamental Research Funds for the Central Universities of China(Grant No.2023JBMC014).
文摘In the railway system,fasteners have the functions of damping,maintaining the track distance,and adjusting the track level.Therefore,routine maintenance and inspection of fasteners are important to ensure the safe operation of track lines.Currently,assessment methods for fastener tightness include manual observation,acoustic wave detection,and image detection.There are limitations such as low accuracy and efficiency,easy interference and misjudgment,and a lack of accurate,stable,and fast detection methods.Aiming at the small deformation characteristics and large elastic change of fasteners from full loosening to full tightening,this study proposes high-precision surface-structured light technology for fastener detection and fastener deformation feature extraction based on the center-line projection distance and a fastener tightness regression method based on neural networks.First,the method uses a 3D camera to obtain a fastener point cloud and then segments the elastic rod area based on the iterative closest point algorithm registration.Principal component analysis is used to calculate the normal vector of the segmented elastic rod surface and extract the point on the centerline of the elastic rod.The point is projected onto the upper surface of the bolt to calculate the projection distance.Subsequently,the mapping relationship between the projection distance sequence and fastener tightness is established,and the influence of each parameter on the fastener tightness prediction is analyzed.Finally,by setting up a fastener detection scene in the track experimental base,collecting data,and completing the algorithm verification,the results showed that the deviation between the fastener tightness regression value obtained after the algorithm processing and the actual measured value RMSE was 0.2196 mm,which significantly improved the effect compared with other tightness detection methods,and realized an effective fastener tightness regression.
文摘When a cold rolled strip is being treated in a continuous annealing furnace which is full of protective gas, the gas tightness of the furnace body, the connected facilities and the gas channels become an important indicator that directly affects the product＇s surface quality and shows the technical level of the design, the manufacture and the installation. By considering the problems of the gas tightness of a vertical annealing furnace in the installation and maintenance, this thesis evaluates the gas tightness indicator and gas tightness related level of the furnace body and the circulation duct, while studying and analyzing the technologies of negative-pressure leak detection and sealing.
文摘Since the tubeless tires and especially cast alloy wheels are used, the air tightness of wheels is an important factor of the automobiles quality. Based on specification of the car industry that up to 10% decrease of the prescribed nominal tire pressure during a time of six-month is allowed, the requirements presented in specifications and norms are treated and validated. The practical experience and influences on the wheel tightness control are discussed and the data presented in a report of a wheel manufacturer, concerning the replacements of wheels in service due to air leakage are evaluated. Summarizing the results of analyses, a proposal is made for the testing of the cast aluminum car wheels to meet the requirements for a reliable and economical air tightness control in modern test facilities.
基金the Science and Research Foundation of Hangzhou Normal University (No.02010180)
文摘In this paper, we discuss tightness and fan tightness of multifunction spaces with pointwise convergence topology or compact-open topology, and generalize some results on con- tinuous single-valued function spaces to continuous multifunction spaces.
基金Zhejiang Provincial Social Science Planning Emerging(Interdisciplinary)Major Support Project,Grant/Award Number:21XXC04ZD。
文摘In recent years,“cultural tightness-looseness”refers to the strength of social norms and tolerance for deviant behaviors perceived by individuals in society,and team cultural tightness applied at the organizational level represents the strength of team norms.According to the cultural tightness-looseness theory,this study explores the influence of team cultural tightness on employee creative behavior,as well as the moderating role of transformational leadership and the mediating role of work engagement.A questionnaire method was used to survey five enterprise organizations in China through three stages,and 288 paired questionnaires were finally obtained from leaders and employees.The results found that team cultural tightness has a significant negative effect on employee creative behavior through the mediating effect of work engagement.In other words,the more the team culture in the workplace tends to be loose,the more it stimulates employee work engagement,which in turn promotes employee creative behavior.In addition,transformational leadership played a significant positive moderating role in the model.Under the influence of transformational leadership style,the negative impact of team cultural tightness on employee work engagement and creative behavior can be mitigated.The study enriches the understanding of the influence and action mechanism of the cultural tightness-looseness theory on employee creative behavior.In future research,the action mechanism of team cultural tightness interacting with different leadership styles to influence employee creative behavior will be explored more deeply.
基金Supported by the National Science Foundation of China(No.10271026)
文摘In this paper, we discuss the countable tightness of products of spaces which are quotient simages of locally separable metric spaces, or k-spaces with a star-countable k-network. The main result is that the following conditions are equivalent： （1） b = ω1; （2） t（Sω×Sω1） 〉 ω; （3） For any pair （X, Y）, which are k-spaces with a point-countable k-network consisting of cosmic subspaces, t（X×Y）≤ω if and only if one of X, Y is first countable or both X, Y are locally cosmic spaces. Many results on the k-space property of products of spaces with certain k-networks could be deduced from the above theorem.
基金supported by the National Natural Science Foundation of China(Grant No.U23A2022)the National Natural Science Foundation of China(Grant No.52474047)+2 种基金the Natural Science Foundation of Chongqing(Grant No.CSTB2024NSCQ-MSX0951)the Natural Science Foundation of Sichuan Province(Grant No.2025ZNSFSC1357)the National Science and Technology Major Project(Grant No.2025ZD1404307).
文摘Injecting impure CO_(2)for enhanced gas recovery(CO_(2)-EGR)offers a dual benefit by improving natural gas extraction while enabling CO_(2)sequestration.However,the interactions between CO_(2),N_(2),and CH_(4)under reservoir conditions require further investigation.This study employs Grand Canonical Monte Carlo(GCMC)and Molecular Dynamics(MD)simulations to quantify the adsorption and diffusion behaviors of CO_(2),N_(2),and CH_(4)in quartz nanopores over a pressure range of 1-24 MPa under varying water saturations and gas compositions.The results indicate that:(1)CO_(2)exhibits the broadest energy distribution and the strongest adsorption stability,occupying about 20%-30%more adsorption sites than CH_(4)or N_(2)and showing the least sensitivity to water saturation,with only a 30%reduction at 50%saturation,compared to 60%for CH_(4),giving CO_(2)a clear competitive advantage.(2)The adsorption and desorption behaviors are strongly pressure dependent,as increasing pressure reduces the adsorption layer area and shifts gas distribution from adsorption dominated to free phase.Competitive adsorption analysis reveals that while CO_(2)dominates displacement at low pressures,mixtures that contain N_(2)achieve higher CH_(4)desorption efficiency above 13 MPa by mitigating diffusion resistance.(3)A higher N_(2)fraction improves CH_(4)diffusion coefficients,thereby facilitating gas mobility and ensuring superior recovery performance under high-pressure conditions.This study advances the fundamental knowledge of microscale gas behavior in tight sandstones and supports the feasibility of impure CO_(2)injection as a practical strategy for sustainable gas production.
基金funding from the National Natural Science Foundation of China(No.U24B6001)the CNPC Innovation Fund(No.2021DQ02-0502).
文摘Re-fracturing horizontal wells is a critical strategy for enhancing recovery from tight oil reservoirs,but its success depends on the evaluation of candidate wells and locations.This process is complicated by production-induced alterations in reservoir pressure and geomechanical responses.This study introduces a workflow to evaluate re-fracturing potential by integrating coupled fluid flow and geomechanical modeling for the production of initial hydraulic fractures.We developed a numerical model that simulates the poroelastic response of a tight oil reservoir to depletion from an initial set of hydraulic fractures.To quantify the re-fracturing potential along the horizontal wellbore,a novel composite re-fracturing potential index is proposed where fracture shape,stress,and pressure are considered.This index considers four key physical factors:current reservoir pressure,fracture initiation ease,fracture geometry favorability,and fracture propagation efficiency considering tortuosity.Numerical simulations were conducted for scenarios with both uniform and non-uniform initial hydraulic fractures.The results consistently demonstrate that the optimal locations for re-fracturing are the midpoints between existing fractures,where a favorable balance of high reservoir pressure and altered stress conditions exists.The analysis reveals that the overall re-fracturing potential tends to increase with production time,suggesting that a period of depletion can enhance the geomechanical conditions for subsequent stimulation.Furthermore,a sensitivity analysis on the index weighting factors shows that the optimum re-fracturing strategy is highly dependent on the primary field objective,whether it is maximizing resource contact,ensuring geomechanical feasibility,or avoiding operational complexity.The study concludes that heterogeneity in the initial fracture network creates complex and asymmetric potential profiles,which implies the necessity of case-specific and integrated analysis over simplified assumptions.The proposed methodology provides a framework for optimizing re-fracturing designs in tight oil reservoirs.
文摘Gastric cancer(GC)is the fifth most prevalent malignancy worldwide and remains a leading cause of cancer-related mortality.Major risk factors for GC include Helicobacter pylori infection,increasing age,high dietary salt intake,and diets deficient in vegetables and fruits.Due to the often subtle and nonspecific early symptoms,coupled with the lack of routine screening programs,a significant proportion of GC cases are diagnosed at advanced stages.The etiology of GC is multifactorial,and diagnosis is confirmed histologically through endoscopic biopsy,followed by staging via computed tomography,positron emission tomography,staging laparoscopy,and endoscopic ultrasound.Treatment strategies typically involve a multidisciplinary approach including chemotherapy,surgical resection,radiotherapy,and emerging immunotherapeutic options.Despite advances in diagnostic and therapeutic modalities,the prognosis of advanced GC remains poor,with high rates of recurrence and metastasis.In recent years,increasing attention has been given to the role of tight junction(TJ)proteins in the pathogenesis and progression of GC.TJ proteins,critical components of epithelial barrier function,have been implicated in various stages of gastric carcinogenesis,from intestinal metaplasia to invasion and metastasis.Infection and inflammation,particularly due to Helicobacter pylori,disrupt TJ integrity,compromising the gastric mucosal barrier and facilitating neoplastic transformation.This review synthesizes current evidence from PubMed,EMBASE,Google Scholar,ScienceDirect,SpringerLink,and other reputable databases to provide a comprehensive overview of the involvement of TJ proteins in GC.By elucidating the molecular interplay between TJ dysregulation and gastric tumorigenesis,this work aims to highlight the potential of TJ proteins as novel diagnostic biomarkers and therapeutic targets in GC management.
文摘Methods of quantum information processing often appear in terms of specially selected states.For example,mutually unbiased bases(MUBs)and symmetric informationally complete measurements are widely applied.Finite frames have found use in many areas including quantum information.Due to its specific inner structure,a single equiangular tight frame(ETF)allows one to formulate criteria to detect non-classical correlations.This study aims to approach entanglement detection with the use of mutually unbiased ETFs.Such frames are an interesting generalization of widely recognized MUBs.It still uses rank-one operators,but the number of outcomes can exceed the dimensionality.Several approaches are considered including separability criteria and entanglement witnesses.Separability criteria for multipartite systems are finally obtained.
基金supported by the National Natural Science Foundation of China,No.82471411(to ZW and TD)the Key Research and DevelopmentProgram of Shaanxi Province,No.2023-ZDLSF-12(to TD).
文摘The blood-spinal cord barrier is crucial for preserving homeostasis of the central nervous system.After spinal cord injury,autophagic flux within endothelial cells is disrupted,compromising the integrity of the blood-spinal cord barrier.This disruption facilitates extensive infiltration of inflammatory cells,resulting in exacerbated neuroinflammatory responses,neuronal death,and impaired neuronal regeneration.Previous research has demonstrated that photobiomodulation promotes the regeneration of damaged nerves following spinal cord injury by inhibiting the recruitment of inflammatory cells to the injured site and restoring neuronal mitochondrial function.However,the precise mechanisms by which photobiomodulation regulates neuroinflammation remain incompletely elucidated.In this study,we established a mouse model of spinal cord injury and assessed the effects of photobiomodulation treatment.Photobiomodulation effectively cleared damaged mitochondria from endothelial cells in mice,promoting recovery of hindlimb motor function.Using microvascular endothelial bEnd.3 cells subjected to oxygen-glucose deprivation,we found that the effects of photobiomodulation were mediated through activation of the PINK1/Parkin pathway.Additionally,photobiomodulation reduced mitochondrial oxidative stress levels and increased the expression of tight junction proteins within the blood-spinal cord barrier.Our findings suggest that photobiomodulation activates mitochondrial autophagy in endothelial cells through the PINK1/Parkin pathway,thereby promoting repair of the blood-spinal cord barrier following spinal cord injury.
基金Supported by the PetroChina Oil,Gas and New Energy Division Science and Technology Special Project(2023YQX10102)。
文摘The concurrent exploration of shale oil wells in the Gulong Sag of the Songliao Basin has uncovered promising hydrocarbon shows in the Fuyu pay zone of the Lower Cretaceous Quantou Formation.To assess the hydrocarbon exploration potential of the Fuyu pay zone,this study systematically analyzes the main controlling factors for hydrocarbon accumulation,including source rock conditions,reservoir characteristics and migration capacity,in the deep area of the Gulong Sag,using seismic,drilling and core data,and reveals the hydrocarbon enrichment mechanism and accumulation model.The results indicate that the source rocks in the first member of Cretaceous Qingshankou Formation(Qing-1 Member)in the Gulong Sag are widely distributed,characterized by high quality,large area,high maturity and high hydrocarbon generation intensity,providing an ample oil source for the Fuyu pay zone.The Fuyu pay zone in the Gulong Sag features multi-phase channel sand bodies and beach-bar sands that are laterally superimposed and vertically stacked,forming large-scale sand-rich reservoir assemblages,which provide the storage space for tight oil enrichment.Influenced by overpressure pore preservation and dissolution-enhanced porosity,the porosity of the Fuyu pay zone can reach up to 13%,meeting the reservoir conditions necessary for large-scale tight oil enrichment.The episodic opening of hydrocarbon-source connected faults during the hydrocarbon expulsion period,combined with source-reservoir pressure differentials,drives the efficient charging and enrichment of hydrocarbons into the underlying tight reservoirs.The hydrocarbon accumulation model of the Fuyu pay zone is summarized as“source-reservoir juxtaposition,overpressure charging,lateral source-reservoir connection+vertical fault-directed bidirectional hydrocarbon supply,continuous sand body distribution,and large-scale enrichment in fault-horst belts”.A new insight for the deep area of the Gulong Sag is proposed as being sand-rich,having superior reservoirs,and being oil-rich.This insight guided the deployment of three risk exploration wells.The Well HT1H achieved a high-yield industrial oil flow rate of 35.27 t/d during testing,discovering light tight oil with low density and low viscosity.Through horizontal well volumetric fracturing treatment,the Well HT1H achieved the first high-yield breakthrough of tight oil in the deep area of the Gulong Sag,confirming the presence of geological conditions for large-scale hydrocarbon accumulation in this area.This expands the potential for hundred-million-ton tight oil resource additions in the Songliao Basin and deepens the theoretical understanding of continental tight oil accumulation.
基金supported by the National Key Research and Development Program of China (Grant Nos.2024YFA1409800 for J.Z.and2024YFA1408603 for Q.Z.)the National Natural Science Foundation of China (Grant Nos.12125408,12334004for J.Z.,and 12174363 for Q.Z.)+1 种基金the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0303306 for J.Z.)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0450101 for J.Z.)。
文摘Electron–hole(e–h)recombination is a fundamental process that governs energy dissipation and device efficiency in semiconductors.In two-dimensional(2D)materials,the formation of tightly bound excitons makes exciton-mediated e–h recombination the dominant decay pathway.In this work,nonradiative e–h recombination within excitons in monolayer MoS_(2) is investigated using first-principles simulations that combine nonadiabatic molecular dynamics with GW and real-time Bethe–Salpeter equation(BSE)propagation.A two-step process is identified:rapid intervalley redistribution induced by exchange interaction,followed by slower phonon-assisted recombination facilitated by exciton binding.By selectively removing the screened Coulomb and exchange terms from the BSE Hamiltonian,their respective contributions are disentangled—exchange interaction is found to increase the number of accessible recombination pathways,while binding reduces the excitation energy and enhances nonradiative decay.A reduction in recombination lifetime by over an order of magnitude is observed due to the excitonic many-body effects.These findings provide microscopic insights for understanding and tuning exciton lifetimes in 2D transition-metal dichalcogenides.
基金supported by the National Natural Science Foundation of China(Grant Nos.42377143 and 52225403)Sichuan Natural Science Foundation(Grant No.2024NSFSC0097).
文摘As an emerging rock-breaking technology,microwave irradiation has demonstrated significant potential as an auxiliary technique for volume stimulation in hydraulic fracturing.This study focuses on tight sandstone gas extraction,introducing a hollow double-wing crack(HDWC)configuration into the research on tight sandstone.Laboratory experiments were conducted to investigate microwave-induced fracturing mechanisms and the mechanical behavior of HDWC-containing sandstone,aiming to elucidate the thermal cracking patterns and underlying mechanisms under microwave irradiation conditions.To further explore the electromagnetic-thermal-mechanical(E-T-M)interactions in tight sandstone under microwave treatment,a coupled finite element method(FEM)-discrete element method(DEM)numerical model was developed.This model enabled a detailed analysis of force chain evolution and microcrack propagation within HDWC-containing sandstone.Additionally,preliminary hydraulic fracturing simulations were performed to investigate fracture initiation pressure and fracture evolution following microwave exposure.The main findings of this study are as follows:(1)Microwave heating induces thermal cracks at both the tips and midsections of the HDWC.Microwave irradiation degrades the mechanical properties of HDWC-containing sandstone.(2)Simulation results reveal that significant stress concentration and tensile-compressive zoning occur near the HDWC under microwave irradiation.Microcrack development exhibits an avalanche effect.(3)Hydraulic fracturing simulations indicate that microwave heating generally promotes hydraulic fracture generation.Microwave irradiation reduces the fracture initiation pressure and enhances the complexity and connectivity of the fracture network.These findings provide valuable insights into the application of microwave-assisted volume stimulation as a supporting technology for hydraulic fracturing in deep reservoirs.
基金supported by the Major Science and Technology Project of PetroChina Company Limited“Research on Key Technologies for Enhancing Recovery in Tight Sandstone Gas Reservoirs”,specifically under its third sub-project:“Research on Integrated Fracturing,Drainage,and Production Technology to Enhance Single-Well Production in Water-Bearing Gas Reservoirs”(Grant number:2023ZZ25YJ03).
文摘To address the persistent challenge of dynamic mismatch between wellbore lifting capacity and reservoir fluid supply,and to establish a robust optimization framework for drainage operations in high-water-cut tight sandstone gas reservoirs,this study systematically investigates the graded optimization and dynamic adaptation of drainage gas recovery technologies.Production data from a representative tight gas field were first employed to forecast reservoir performance.The predictive reliability was rigorously validated through high-precision history matching,thereby providing a quantitatively consistent foundation for subsequent wellbore optimization.Building on this characterization,a coupled simulation framework was developed that integrates wellbore multiphase flow modeling with nodal analysis based on the Inflow Performance Relationship,IPR,and the Vertical Lift Performance,VLP.This coordinated approach enables comprehensive evaluation of process adaptability and dynamic optimization of foam-assisted drainage,mechanical pumping,and jet pumping systems under evolving water-gas ratio,WGR conditions.The results reveal that a progressively increasing water-gas ratio is the dominant factor driving the transition from chemically assisted drainage methods to mechanically enhanced lifting technologies.A distinct quantitative threshold is identified at WGR≈0.002,beyond which mechanical intervention becomes more effective and economically justified.For mechanical pumping and jet pumping systems,a parameter inversion optimization strategy constrained by the target bottomhole flowing pressure,Pwf,is proposed to ensure stable production while maintaining reservoir drawdown control.In particular,the nozzle-to-throat area ratio of the jet pump is identified as the key governing parameter influencing entrainment capacity and lifting efficiency.Moreover,a configuration characterized by small pump diameter,long stroke length,and low operating speed is demonstrated to satisfy drainage requirements while mitigating torque fluctuations,enhancing volumetric efficiency,and improving pump fillage stability.
基金supported by the National Science and Technology Project of China(No.2024ZD1004300)。
文摘The effective channeling of fluid flow by fractures is a liability for enhanced oil recovery(EOR)methods like CO_(2) flooding or CO_(2) storage.Developing a distributed fracture model to understand the heterogeneity of the fracture network is essential in characterizing tight and low-permeability reservoirs.In the Ordos Basin,the Chang 8-1-2 layer of the Yanchang Formation is a typical tight and low permeability reservoir in the JH17 wellblock.The strong heterogeneity of distributed fractures,differing fracture scales and fracture types make it difficult to effectively characterize the fracture distribution within the Chang 8-1-2 layer.In this paper,multi-source and multi-attribute methods are used to integrate data into a neural network at different scales,and fuzzy logic control is used to judge the correlation of various attributes.The results suggest that attribute correlation between coherence and fracture indication is the best,followed by correlations with fault distance,north–south slope,and north–south curvature.Advantageous attributes from the target area are used to train the neural network,and the fracture density model and discrete fracture network(DFN)model are built at different scales.This method can be used to effectively predict the distribution characteristics of fractures in the study area.And any learning done by the neural network from this case study can be applied to fracture network modeling for reservoirs of the same type.
