In this work, a new method to deal with the unconnected pixels in motion compensated temporal filtering (MCTF) is presented, which is designed to improve the performance of 3D lifted wavelet coding. Furthermore, multi...In this work, a new method to deal with the unconnected pixels in motion compensated temporal filtering (MCTF) is presented, which is designed to improve the performance of 3D lifted wavelet coding. Furthermore, multiple description scalable coding (MDSC) is investigated, and novel MDSC schemes based on 3D wavelet coding are proposed, using the lifting imple- mentation of temporal filtering. The proposed MDSC schemes can avoid the mismatch problem in multiple description video coding, and have high scalability and robustness of video transmission. Experimental results showed that the proposed schemes are feasible and adequately effective.展开更多
This paper addresses an iterative learning control(ILC) design problem for discrete-time linear systems with randomly varying trial lengths. Due to the variation of the trial lengths, a stochastic matrix and an iterat...This paper addresses an iterative learning control(ILC) design problem for discrete-time linear systems with randomly varying trial lengths. Due to the variation of the trial lengths, a stochastic matrix and an iteration-average operator are introduced to present a unified expression of ILC scheme. By using the framework of lifted system, the learning convergence condition of ILC in mathematical expectation is derived without using λ-norm. It is shown that the requirement on classic ILC that all trial lengths must be identical is mitigated and the identical initialization condition can be also removed. In the end, two illustrative examples are presented to demonstrate the performance and the effectiveness of the proposed ILC scheme for both time-invariant and time-varying linear systems.展开更多
Flame stabilization is the key to extending scramjets to hypersonic speeds;accordingly,this topic has attracted much attention in theoretical research and engineering design.This study performed large eddy simulations...Flame stabilization is the key to extending scramjets to hypersonic speeds;accordingly,this topic has attracted much attention in theoretical research and engineering design.This study performed large eddy simulations(LESs)of lifted hydrogen jet combustion in a stepped-wall combustor,focusing on the flame stabilization mechanisms,especially for the autoignition effect.An assumed probability density function(PDF)approach was used to close the subgrid chemical reaction source.The reliability of the solver was confirmed by comparing the LES results with experimental data and published simulated results.The hydrogen jet and the incoming stream were first mixed by entraining large-scale vortices in the shear layer,and stable combustion in the near-wall region was achieved downstream of the flame induction region.The autoignition cascade is a transition of fuel-rich flame to stoichiometric ratio flame that plays a role in forming the flame base,which subsequently causes downstream flame stabilization.Three cases with different jet total temperatures are compared,and the results show that the increase in the total temperature reduces the lift-off distance of the flame.In the highest total temperature case,an excessively large scalar dissipation rate inhibits the autoignition cascade,resulting in a fuel-rich low-temperature flame.展开更多
In this paper,a lifted Haar transform(LHT)image compression optical chip has been researched to achieve rapid image compression.The chip comprises 32 same image compression optical circuits,and each circuit contains a...In this paper,a lifted Haar transform(LHT)image compression optical chip has been researched to achieve rapid image compression.The chip comprises 32 same image compression optical circuits,and each circuit contains a 2×2 multimode interference(MMI)coupler and aπ/2 delay line phase shifter as the key components.The chip uses highly borosilicate glass as the substrate,Su8 negative photoresist as the core layer,and air as the cladding layer.Its horizontal and longitudinal dimensions are 8011μm×10000μm.Simulation results present that the designed optical circuit has a coupling ratio(CR)of 0:100 and an insertion loss(IL)of 0.001548 d B.Then the chip is fabricated by femtosecond laser and testing results illustrate that the chip has a CR of 6:94 and an IL of 0.518 d B.So,the prepared chip possesses good image compression performance.展开更多
This essay will investigate the differences between the ways George Eliot’s protagonist,Latimer,and Cajal’s protagonist,Juan Fernández,handle the extraordinary visions they are given.In“The Lifted Veil”by Geo...This essay will investigate the differences between the ways George Eliot’s protagonist,Latimer,and Cajal’s protagonist,Juan Fernández,handle the extraordinary visions they are given.In“The Lifted Veil”by George Eliot,Latimer acquires a gift of clairvoyance,which enables him to see others’thoughts.Similarly,in“The Corrected Pessimist,”a novella in Cajal’s story collection—Vacation Stories,Juan acquires microscopic eyes,which enable him to lift the veil of reality and in turn that of the human mind.While Juan learns to zoom in on the beauty of the human mind and to use his appreciation of its beauty to understand its flaws,Latimer excessively zooms in on the dark side of the human mind and fails to sympathize with others.In comparing the different ways in which Latimer and Juan employ their microscopic visions,this essay aims to prove that Eliot and Cajal,though through contrasting ways,both highlight how important is shifting perspectives to cultivate one’s sympathy.展开更多
Races using kitefoil and windfoil surfboards have been in the Olympic Games for the first time in Paris 2024,signalling their relevance in sailing sports.However,the dynamics of these devices is yet not well understoo...Races using kitefoil and windfoil surfboards have been in the Olympic Games for the first time in Paris 2024,signalling their relevance in sailing sports.However,the dynamics of these devices is yet not well understood,in particular the influence on the hydrodynamic forces and moments of the distance of the foil to the free surface.Considering this,the present paper documents an experimental investigation in which forces and torque produced,under uniform flow,by a full-scale state-of-the-art hydrofoil(suitable both for kitesurf and windsurf)were measured.A range of velocities,angles of attack,and submergences were tested,leading to Froude numbers based on submergence with maximum values around five,a typical range in actual sailing conditions.From these tests,formulae for the hydrodynamic coefficients have been proposed.They can be used for developing Velocity Prediction Programs(VPP)for this kind of craft,a necessary tool to plan racing configurations and to analyze their racing performance.With the aim of making the experimental data useful for benchmarking numerical models and for future research on related topics such as foil ventilation and transition to turbulence,the specimen’s 3D file is provided as supplementary material to this paper.展开更多
The worldwide increase in energy demand necessitates the development and optimization of marginal oil fields for sustenance.In this regard,effective and economic production of fluids are heavily relied upon the artifi...The worldwide increase in energy demand necessitates the development and optimization of marginal oil fields for sustenance.In this regard,effective and economic production of fluids are heavily relied upon the artificial lift techniques as the reservoir's natural energy may not be able to deliver the fluids to the surface.Gas lift is a widely practised and successful method that is suitable for rejuvenating the oil production from such fields.In this study,the influence of critical parameters like water cut,wellhead pressure(WHP)and gas-lift gas injection rate on the output from a gas lifted well was analysed.A significant reduction in the oil production was observed with the increase in water cut.For a fixed gas injection rate of 1 Mmscf/day,the production decreased by 26.90%when the water cut increased from 15%to 30%and further by 50.80%when the water cut reached 45%.An increase in the gas injection rate from 1 Mmscf/day to 8 Mmscf/day resulted in an increase in the production rate by 29.21%,40.48%and 56.56%for 15%,30%,and 45%water cut conditions,respectively.It was observed that there is a drop in the oil rate with the increase in WHP for a constant gas injection rate.An increase in the WHP from 100 psi to 300 psi resulted in a drop in the oil production rate by 11.01%,11.78%and 12.74%for 15%,30%and 45%water cut conditions,respectively.The study sheds light on the significance of optimizing the critical parameters to maximize the production from a well,with severely affected productivity,using a continuous gas lift system.展开更多
Words are like magic.They can lift you up,or they can knock you down.They are the most powerful tool we have.When I was in Grade 7,I performed badly in a math test.
Laughter is a universal language that brings people together.Among all forms of laughter,a loud laugh is particularly powerful.When someone laughs loudly,it can lift the mood of everyone nearby and create a joyful atm...Laughter is a universal language that brings people together.Among all forms of laughter,a loud laugh is particularly powerful.When someone laughs loudly,it can lift the mood of everyone nearby and create a joyful atmosphere.展开更多
Rising demand for minerals and metals in high-tech and new energy industries has led to a great interest in exploration of seabed mineral resources.Such resources,including polymetallic nodule(PMN),polymetallic sulphi...Rising demand for minerals and metals in high-tech and new energy industries has led to a great interest in exploration of seabed mineral resources.Such resources,including polymetallic nodule(PMN),polymetallic sulphide(PMS),and cobalt-rich ferromanganese crust(CFC),are considered as an alternative source of metals to terrestrial deposits.Although a considerable number of sea trials of deep-sea mining have been carried out,the deep-sea mining does not achieve the commercial exploitation due to the complexity of deep-sea mining system and deep-sea mining environment.In fact,to achieve commercial deep-sea mining,the technology and equipment of deep-sea mining are the key points.Therefore,the present study presents the development of the technology and equipment of deep-sea mining.It commences with a requirement of technology and equipment for deep-sea mining,including environmental impact,reliability,energy cost,efficiency,etc.Then,a historical perspective and present-day effort related to deep-sea mining vehicles are given,which highlights the evolution of collection mechanism and walking mode of deep-sea mining vehicle.Subsequently,the present study discusses the operation of subsea lifting system and surface support system,shedding light on the crucial equipment and processes.The challenges and prospects in the deep-sea mining are presented in final,including environmental protection,self-propelled crawler,hydraulic pipeline lifting,and intelligent equipment,etc.展开更多
In August 2019,accompanied by an Arctic warming event,elevated thunderstorms crossed over the North Pole(NP)and produced lightning.The northernmost stroke occurred less than 50 km from the NP,marking the closest strok...In August 2019,accompanied by an Arctic warming event,elevated thunderstorms crossed over the North Pole(NP)and produced lightning.The northernmost stroke occurred less than 50 km from the NP,marking the closest stroke to the NP ever recorded.Using ERA5 reanalysis data and satellite observations,we investigated the background and development mechanism of this event.Warm and moist air from low latitudes was transported northward to the vicinity of the North Pole by the 850-h Pa jet,resulting in convergence.Through the combined effects of frontal lifting and the presence of underlying cold air,the warm and moist air was lifted to heights above the melting layer,triggering elevated thunderstorms above the frontal boundary.These findings describe a strong link between warming events and thunderstorms,revealing the formation mechanisms of elevated thunderstorms in the Arctic.In the context of rapid Arctic warming,this study provides preliminary insights into the meteorological conditions conducive to thunderstorm formation in the region.展开更多
Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally p...Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally patterned microchannels with precisely controlled morphologies using the projection micro-stereolithography(PμSL)-based 3D printing technique.Our helicoidally patterned microchannels achieve approximately twice the liquid lifting height compared to similarly sized smooth microchannels.This improvement is attributed to the enhanced capillary force.The additional meniscus formed between the helicoidally patterned microstructures significantly contributes to the increased capillary effects.Furthermore,the underlying mechanisms of fluidic performance in helicoidally patterned microchannels are theorized using a newly developed equation,which is also employed to optimize the geometric parameters and fluidic performance of the biomimetic helicoidal microchannels.Additionally,our biomimetic helicoidally patterned microchannels facilitate a significant step-lifting phenomenon,mimicking tall trees'transpiration.The fluidic performance of our biomimetic helicoidally patterned microchannels show promise for applications in enhanced liquid lifting,step-lifting,clean-water production,and others.展开更多
As the environmental problems become increasingly serious,distributed electrical propulsion systems with higher aerodynamic efficiency and lower pollution emission have received extensive attention in recent years.The...As the environmental problems become increasingly serious,distributed electrical propulsion systems with higher aerodynamic efficiency and lower pollution emission have received extensive attention in recent years.The distributed electrical propulsion usually employs the new aero-propulsion integrated configuration.A simulation strategy for internal and external flow coupling based on the combination of lifting line theory and body force method is proposed.The lifting line theory and body force method as source term are embedded into the Navier-Stokes formulation.The lift and drag characteristics of the aero-propulsion coupling configuration are simulated.The results indicate that the coupling configuration has the most obvious lift augmentation at 12°angle of attack,which can provide an 11.11%increase in lift for the airfoil.At 0°angle of attack,the pressure difference on the lip parts provides the thrust component,which results in a lower drag coefficient.Additionally,the failure impact of a ducted fan at the middle or edge on aerodynamics is investigated.For the two failure conditions,the lift of the coupling configuration is decreased significantly by 27.85%and 26.14%respectively,and the lip thrust is decreased by 70.74%and 56.48%respectively.展开更多
Timely anomaly detection is critical for optimizing gas production in plunger lift systems,where equipment failures and operational issues can cause significant disruptions.This paper introduces a two-dimensional conv...Timely anomaly detection is critical for optimizing gas production in plunger lift systems,where equipment failures and operational issues can cause significant disruptions.This paper introduces a two-dimensional convolutional neural network(2D-CNN)model designed to diagnose abnormal operating conditions in gas wells utilizing plunger lift technology.The model was trained using an extensive dataset comprising casing and tubing pressure measurements gathered from multiple wells experiencing both normal and anomalous operations.Input data underwent a rigorous preprocessing pipeline involving cleaning,ratio calculation,window segmentation,and matrix transformation.Employing separate pre-training and transfer learning methods,the model's efficacy was validated through stringent testing on new,previously unseen field data.Results demonstrate the model's acceptable performance and strong diagnostic capabilities on this novel data from various wells within the operational block.This confirms its potential to fulfill practical field requirements by offering guidance for adjusting production systems in plunger lift-assisted wells.Ultimately,this data-driven,automated diagnostic approach provides valuable theoretical insights and technical support for sustaining gas well production rates.展开更多
BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,sli...BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,slight postoperative pain,faster recovery.Despite the advantages mentioned above,the currently available specialized single-port laparoscopic instruments are hindered by high costs and limited applications,challenging their widespread use in medical facilities.AIM To design a two-point lifting/retracting(TPLR)technique for transumbilical single-port LC(TUSPLC)based on the anatomical features of the Calot's triangle(or cystohepatic triangle)and investigate its surgical feasibility.METHODS The clinical data of 103 patients who underwent TUSPLC utilizing the TPLR technique in the Department of Hepatobiliary Surgery at our hospital between June 2023 and June 2024 were retrospectively analyzed.The patient cohort included 82 cases of cholelithiasis,11 cases of gallbladder polyps,6 cases of concurrent gallstones and polyps,and 4 cases of gallbladder adenomyomatosis.RESULTS All the surgical procedures were conducted using standard laparoscopic instruments.Surgery was successful in 98(95.14%)patients using the TPLR method,which effectively exposed the Calot's triangle during surgery.The operative time ranged from 35 to 70 minutes,with an average of 42.4±26.8 minutes.In 3 cases,an additional operative port was required below the xiphoid process,and 2 cases were converted to conventional three-port LC.No complications such as abdominal pain,fever,bile leakage,hemorrhage,or incisional infection were noted postoperatively.No discernible surgical scars were observed at the 2-week postoperative reexamination.Additionally,a 3-month follow-up period revealed no complications.CONCLUSION The TPLR technique,developed based on the anatomical features of the Calot's triangle,facilitates exposure of the Calot's triangle during surgery.It is a simple,safe,feasible,and cost-effective method,and a promising approach for single-port LC.展开更多
In the mid-to-late stages of gas reservoir development,liquid loading in gas wells becomes a common challenge.Plunger lift,as an intermittent production technique,is widely used for deliquification in gas wells.With t...In the mid-to-late stages of gas reservoir development,liquid loading in gas wells becomes a common challenge.Plunger lift,as an intermittent production technique,is widely used for deliquification in gas wells.With the advancement of big data and artificial intelligence,the future of oil and gas field development is trending towards intelligent,unmanned,and automated operations.Currently,the optimization of plunger lift working systems is primarily based on expert experience and manual control,focusing mainly on the success of the plunger lift without adequately considering the impact of different working systems on gas production.Additionally,liquid loading in gas wells is a dynamic process,and the intermittent nature of plunger lift requires accurate modeling;using constant inflow dynamics to describe reservoir flow introduces significant errors.To address these challenges,this study establishes a coupled wellbore-reservoir model for plunger lift wells and validates the computational wellhead pressure results against field measurements.Building on this model,a novel optimization control algorithm based on the deep deterministic policy gradient(DDPG)framework is proposed.The algorithm aims to optimize plunger lift working systems to balance overall reservoir pressure,stabilize gas-water ratios,and maximize gas production.Through simulation experiments in three different production optimization scenarios,the effectiveness of reinforcement learning algorithms(including RL,PPO,DQN,and the proposed DDPG)and traditional optimization algorithms(including GA,PSO,and Bayesian optimization)in enhancing production efficiency is compared.The results demonstrate that the coupled model provides highly accurate calculations and can precisely describe the transient production of wellbore and gas reservoir systems.The proposed DDPG algorithm achieves the highest reward value during training with minimal error,leading to a potential increase in cumulative gas production by up to 5%and cumulative liquid production by 252%.The DDPG algorithm exhibits robustness across different optimization scenarios,showcasing excellent adaptability and generalization capabilities.展开更多
During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the ti...During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the tilt of the field surface,this research developed an innovative dual-parallelogram chassis lifting mechanism for rice harvesters designed a hydraulic system to adjust the chassis height by extending the cylinder.Using Adams simulation software,a detailed model of the lifting chassis was constructed to analyze its performance,revealing a direct correlation between the hydraulic cylinder extension and chassis elevation.Notably,the mechanism could achieve leveling on slopes with inclination angles of up to 7.5°.Comprehensive evaluations of the liftable chassis system were conducted under both static and dynamic conditions.In the static tests,the system exhibited the capacity for comprehensive or unilateral auto-leveling contingent upon the tilt,with leveling times and angular variations confined to 3.6 s and±0.4°,respectively.In dynamic tests conducted on sloped fields and paddy soils,the system reduced post-leveling mean tilt angles and standard deviations remained below 1.2°and 0.6°,respectively.These results demonstrated a substantial improvement in the stability and reliability of the chassis during operations.This research provides valuable insights into the design and optimization of automatic leveling mechanisms and structural innovations for harvester chassis.展开更多
基金Project supported by the National Natural Science Foundation ofChina (No. 60472100), the Natural Science Foundation of ZhejiangProvince (Nos. RC01057, Y105577, 601017), the Ningbo Scienceand Technology Project (Nos. 2003A61001, 2004A610001,2004A630002), and the Zhejiang Science and Technology Project(No. 2004C31105), China
文摘In this work, a new method to deal with the unconnected pixels in motion compensated temporal filtering (MCTF) is presented, which is designed to improve the performance of 3D lifted wavelet coding. Furthermore, multiple description scalable coding (MDSC) is investigated, and novel MDSC schemes based on 3D wavelet coding are proposed, using the lifting imple- mentation of temporal filtering. The proposed MDSC schemes can avoid the mismatch problem in multiple description video coding, and have high scalability and robustness of video transmission. Experimental results showed that the proposed schemes are feasible and adequately effective.
文摘This paper addresses an iterative learning control(ILC) design problem for discrete-time linear systems with randomly varying trial lengths. Due to the variation of the trial lengths, a stochastic matrix and an iteration-average operator are introduced to present a unified expression of ILC scheme. By using the framework of lifted system, the learning convergence condition of ILC in mathematical expectation is derived without using λ-norm. It is shown that the requirement on classic ILC that all trial lengths must be identical is mitigated and the identical initialization condition can be also removed. In the end, two illustrative examples are presented to demonstrate the performance and the effectiveness of the proposed ILC scheme for both time-invariant and time-varying linear systems.
基金National Natural Science Foundation of China(Nos.91741205 and 11522222)。
文摘Flame stabilization is the key to extending scramjets to hypersonic speeds;accordingly,this topic has attracted much attention in theoretical research and engineering design.This study performed large eddy simulations(LESs)of lifted hydrogen jet combustion in a stepped-wall combustor,focusing on the flame stabilization mechanisms,especially for the autoignition effect.An assumed probability density function(PDF)approach was used to close the subgrid chemical reaction source.The reliability of the solver was confirmed by comparing the LES results with experimental data and published simulated results.The hydrogen jet and the incoming stream were first mixed by entraining large-scale vortices in the shear layer,and stable combustion in the near-wall region was achieved downstream of the flame induction region.The autoignition cascade is a transition of fuel-rich flame to stoichiometric ratio flame that plays a role in forming the flame base,which subsequently causes downstream flame stabilization.Three cases with different jet total temperatures are compared,and the results show that the increase in the total temperature reduces the lift-off distance of the flame.In the highest total temperature case,an excessively large scalar dissipation rate inhibits the autoignition cascade,resulting in a fuel-rich low-temperature flame.
基金the Natural Science Foundation of Hubei Province(No.2017CFB685)Hubei University of Technology"Advanced Manufacturing Technology and Equipment"Collaborative Innovation Center Open Research Fund(Nos.038/1201501 and 038/1201803)the College-level Project of Hubei University of Technology(Nos.4201/01758,4201/01802,4201/01889,and 4128/21025)。
文摘In this paper,a lifted Haar transform(LHT)image compression optical chip has been researched to achieve rapid image compression.The chip comprises 32 same image compression optical circuits,and each circuit contains a 2×2 multimode interference(MMI)coupler and aπ/2 delay line phase shifter as the key components.The chip uses highly borosilicate glass as the substrate,Su8 negative photoresist as the core layer,and air as the cladding layer.Its horizontal and longitudinal dimensions are 8011μm×10000μm.Simulation results present that the designed optical circuit has a coupling ratio(CR)of 0:100 and an insertion loss(IL)of 0.001548 d B.Then the chip is fabricated by femtosecond laser and testing results illustrate that the chip has a CR of 6:94 and an IL of 0.518 d B.So,the prepared chip possesses good image compression performance.
文摘This essay will investigate the differences between the ways George Eliot’s protagonist,Latimer,and Cajal’s protagonist,Juan Fernández,handle the extraordinary visions they are given.In“The Lifted Veil”by George Eliot,Latimer acquires a gift of clairvoyance,which enables him to see others’thoughts.Similarly,in“The Corrected Pessimist,”a novella in Cajal’s story collection—Vacation Stories,Juan acquires microscopic eyes,which enable him to lift the veil of reality and in turn that of the human mind.While Juan learns to zoom in on the beauty of the human mind and to use his appreciation of its beauty to understand its flaws,Latimer excessively zooms in on the dark side of the human mind and fails to sympathize with others.In comparing the different ways in which Latimer and Juan employ their microscopic visions,this essay aims to prove that Eliot and Cajal,though through contrasting ways,both highlight how important is shifting perspectives to cultivate one’s sympathy.
文摘Races using kitefoil and windfoil surfboards have been in the Olympic Games for the first time in Paris 2024,signalling their relevance in sailing sports.However,the dynamics of these devices is yet not well understood,in particular the influence on the hydrodynamic forces and moments of the distance of the foil to the free surface.Considering this,the present paper documents an experimental investigation in which forces and torque produced,under uniform flow,by a full-scale state-of-the-art hydrofoil(suitable both for kitesurf and windsurf)were measured.A range of velocities,angles of attack,and submergences were tested,leading to Froude numbers based on submergence with maximum values around five,a typical range in actual sailing conditions.From these tests,formulae for the hydrodynamic coefficients have been proposed.They can be used for developing Velocity Prediction Programs(VPP)for this kind of craft,a necessary tool to plan racing configurations and to analyze their racing performance.With the aim of making the experimental data useful for benchmarking numerical models and for future research on related topics such as foil ventilation and transition to turbulence,the specimen’s 3D file is provided as supplementary material to this paper.
文摘The worldwide increase in energy demand necessitates the development and optimization of marginal oil fields for sustenance.In this regard,effective and economic production of fluids are heavily relied upon the artificial lift techniques as the reservoir's natural energy may not be able to deliver the fluids to the surface.Gas lift is a widely practised and successful method that is suitable for rejuvenating the oil production from such fields.In this study,the influence of critical parameters like water cut,wellhead pressure(WHP)and gas-lift gas injection rate on the output from a gas lifted well was analysed.A significant reduction in the oil production was observed with the increase in water cut.For a fixed gas injection rate of 1 Mmscf/day,the production decreased by 26.90%when the water cut increased from 15%to 30%and further by 50.80%when the water cut reached 45%.An increase in the gas injection rate from 1 Mmscf/day to 8 Mmscf/day resulted in an increase in the production rate by 29.21%,40.48%and 56.56%for 15%,30%,and 45%water cut conditions,respectively.It was observed that there is a drop in the oil rate with the increase in WHP for a constant gas injection rate.An increase in the WHP from 100 psi to 300 psi resulted in a drop in the oil production rate by 11.01%,11.78%and 12.74%for 15%,30%and 45%water cut conditions,respectively.The study sheds light on the significance of optimizing the critical parameters to maximize the production from a well,with severely affected productivity,using a continuous gas lift system.
文摘Words are like magic.They can lift you up,or they can knock you down.They are the most powerful tool we have.When I was in Grade 7,I performed badly in a math test.
文摘Laughter is a universal language that brings people together.Among all forms of laughter,a loud laugh is particularly powerful.When someone laughs loudly,it can lift the mood of everyone nearby and create a joyful atmosphere.
基金the National Science Fund for Distinguished Young Scholars(Grant No.52225107)National Key Research and Development Program of China(Grant No.2021YFC2801503)for funding provided to this work.
文摘Rising demand for minerals and metals in high-tech and new energy industries has led to a great interest in exploration of seabed mineral resources.Such resources,including polymetallic nodule(PMN),polymetallic sulphide(PMS),and cobalt-rich ferromanganese crust(CFC),are considered as an alternative source of metals to terrestrial deposits.Although a considerable number of sea trials of deep-sea mining have been carried out,the deep-sea mining does not achieve the commercial exploitation due to the complexity of deep-sea mining system and deep-sea mining environment.In fact,to achieve commercial deep-sea mining,the technology and equipment of deep-sea mining are the key points.Therefore,the present study presents the development of the technology and equipment of deep-sea mining.It commences with a requirement of technology and equipment for deep-sea mining,including environmental impact,reliability,energy cost,efficiency,etc.Then,a historical perspective and present-day effort related to deep-sea mining vehicles are given,which highlights the evolution of collection mechanism and walking mode of deep-sea mining vehicle.Subsequently,the present study discusses the operation of subsea lifting system and surface support system,shedding light on the crucial equipment and processes.The challenges and prospects in the deep-sea mining are presented in final,including environmental protection,self-propelled crawler,hydraulic pipeline lifting,and intelligent equipment,etc.
基金supported by the National Key Research and Development Program of China(2023YFC3007703)National Natural Science Foundation of China(Grant Nos.41675066,42394122)+1 种基金CAS Project of Stable Support for Youth Team in Basic Research Field(YSRR-018)the Chinese Meridian Project。
文摘In August 2019,accompanied by an Arctic warming event,elevated thunderstorms crossed over the North Pole(NP)and produced lightning.The northernmost stroke occurred less than 50 km from the NP,marking the closest stroke to the NP ever recorded.Using ERA5 reanalysis data and satellite observations,we investigated the background and development mechanism of this event.Warm and moist air from low latitudes was transported northward to the vicinity of the North Pole by the 850-h Pa jet,resulting in convergence.Through the combined effects of frontal lifting and the presence of underlying cold air,the warm and moist air was lifted to heights above the melting layer,triggering elevated thunderstorms above the frontal boundary.These findings describe a strong link between warming events and thunderstorms,revealing the formation mechanisms of elevated thunderstorms in the Arctic.In the context of rapid Arctic warming,this study provides preliminary insights into the meteorological conditions conducive to thunderstorm formation in the region.
基金supported by National Natural Science Foundation of China through Grant Nos.52495000,52332012 and 52176093partially supported by Beijing Huiyangdao Health Technology Co.,Ltd。
文摘Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally patterned microchannels with precisely controlled morphologies using the projection micro-stereolithography(PμSL)-based 3D printing technique.Our helicoidally patterned microchannels achieve approximately twice the liquid lifting height compared to similarly sized smooth microchannels.This improvement is attributed to the enhanced capillary force.The additional meniscus formed between the helicoidally patterned microstructures significantly contributes to the increased capillary effects.Furthermore,the underlying mechanisms of fluidic performance in helicoidally patterned microchannels are theorized using a newly developed equation,which is also employed to optimize the geometric parameters and fluidic performance of the biomimetic helicoidal microchannels.Additionally,our biomimetic helicoidally patterned microchannels facilitate a significant step-lifting phenomenon,mimicking tall trees'transpiration.The fluidic performance of our biomimetic helicoidally patterned microchannels show promise for applications in enhanced liquid lifting,step-lifting,clean-water production,and others.
基金the funding support from the Taihang Laboratory,China(No.D2024-1-0201).
文摘As the environmental problems become increasingly serious,distributed electrical propulsion systems with higher aerodynamic efficiency and lower pollution emission have received extensive attention in recent years.The distributed electrical propulsion usually employs the new aero-propulsion integrated configuration.A simulation strategy for internal and external flow coupling based on the combination of lifting line theory and body force method is proposed.The lifting line theory and body force method as source term are embedded into the Navier-Stokes formulation.The lift and drag characteristics of the aero-propulsion coupling configuration are simulated.The results indicate that the coupling configuration has the most obvious lift augmentation at 12°angle of attack,which can provide an 11.11%increase in lift for the airfoil.At 0°angle of attack,the pressure difference on the lip parts provides the thrust component,which results in a lower drag coefficient.Additionally,the failure impact of a ducted fan at the middle or edge on aerodynamics is investigated.For the two failure conditions,the lift of the coupling configuration is decreased significantly by 27.85%and 26.14%respectively,and the lip thrust is decreased by 70.74%and 56.48%respectively.
基金the support of the National Natural Science Foundation of China(Grant No.52474064)Frontier Interdisciplinary Exploration Research Program of China University of Petroleum,Beijing(Grant No.2462024XKQY005).
文摘Timely anomaly detection is critical for optimizing gas production in plunger lift systems,where equipment failures and operational issues can cause significant disruptions.This paper introduces a two-dimensional convolutional neural network(2D-CNN)model designed to diagnose abnormal operating conditions in gas wells utilizing plunger lift technology.The model was trained using an extensive dataset comprising casing and tubing pressure measurements gathered from multiple wells experiencing both normal and anomalous operations.Input data underwent a rigorous preprocessing pipeline involving cleaning,ratio calculation,window segmentation,and matrix transformation.Employing separate pre-training and transfer learning methods,the model's efficacy was validated through stringent testing on new,previously unseen field data.Results demonstrate the model's acceptable performance and strong diagnostic capabilities on this novel data from various wells within the operational block.This confirms its potential to fulfill practical field requirements by offering guidance for adjusting production systems in plunger lift-assisted wells.Ultimately,this data-driven,automated diagnostic approach provides valuable theoretical insights and technical support for sustaining gas well production rates.
文摘BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,slight postoperative pain,faster recovery.Despite the advantages mentioned above,the currently available specialized single-port laparoscopic instruments are hindered by high costs and limited applications,challenging their widespread use in medical facilities.AIM To design a two-point lifting/retracting(TPLR)technique for transumbilical single-port LC(TUSPLC)based on the anatomical features of the Calot's triangle(or cystohepatic triangle)and investigate its surgical feasibility.METHODS The clinical data of 103 patients who underwent TUSPLC utilizing the TPLR technique in the Department of Hepatobiliary Surgery at our hospital between June 2023 and June 2024 were retrospectively analyzed.The patient cohort included 82 cases of cholelithiasis,11 cases of gallbladder polyps,6 cases of concurrent gallstones and polyps,and 4 cases of gallbladder adenomyomatosis.RESULTS All the surgical procedures were conducted using standard laparoscopic instruments.Surgery was successful in 98(95.14%)patients using the TPLR method,which effectively exposed the Calot's triangle during surgery.The operative time ranged from 35 to 70 minutes,with an average of 42.4±26.8 minutes.In 3 cases,an additional operative port was required below the xiphoid process,and 2 cases were converted to conventional three-port LC.No complications such as abdominal pain,fever,bile leakage,hemorrhage,or incisional infection were noted postoperatively.No discernible surgical scars were observed at the 2-week postoperative reexamination.Additionally,a 3-month follow-up period revealed no complications.CONCLUSION The TPLR technique,developed based on the anatomical features of the Calot's triangle,facilitates exposure of the Calot's triangle during surgery.It is a simple,safe,feasible,and cost-effective method,and a promising approach for single-port LC.
基金support from Science Foundation of China University of Petroleum,Beijing(No.2462023YJRC019)National Natural Science Foundation of China(No.52204059)Key Core Technology Research Project Foundation of PetroChina Group(No.2023ZG18).
文摘In the mid-to-late stages of gas reservoir development,liquid loading in gas wells becomes a common challenge.Plunger lift,as an intermittent production technique,is widely used for deliquification in gas wells.With the advancement of big data and artificial intelligence,the future of oil and gas field development is trending towards intelligent,unmanned,and automated operations.Currently,the optimization of plunger lift working systems is primarily based on expert experience and manual control,focusing mainly on the success of the plunger lift without adequately considering the impact of different working systems on gas production.Additionally,liquid loading in gas wells is a dynamic process,and the intermittent nature of plunger lift requires accurate modeling;using constant inflow dynamics to describe reservoir flow introduces significant errors.To address these challenges,this study establishes a coupled wellbore-reservoir model for plunger lift wells and validates the computational wellhead pressure results against field measurements.Building on this model,a novel optimization control algorithm based on the deep deterministic policy gradient(DDPG)framework is proposed.The algorithm aims to optimize plunger lift working systems to balance overall reservoir pressure,stabilize gas-water ratios,and maximize gas production.Through simulation experiments in three different production optimization scenarios,the effectiveness of reinforcement learning algorithms(including RL,PPO,DQN,and the proposed DDPG)and traditional optimization algorithms(including GA,PSO,and Bayesian optimization)in enhancing production efficiency is compared.The results demonstrate that the coupled model provides highly accurate calculations and can precisely describe the transient production of wellbore and gas reservoir systems.The proposed DDPG algorithm achieves the highest reward value during training with minimal error,leading to a potential increase in cumulative gas production by up to 5%and cumulative liquid production by 252%.The DDPG algorithm exhibits robustness across different optimization scenarios,showcasing excellent adaptability and generalization capabilities.
基金Sichuan Science and Technology Program(2022YFG0077)。
文摘During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the tilt of the field surface,this research developed an innovative dual-parallelogram chassis lifting mechanism for rice harvesters designed a hydraulic system to adjust the chassis height by extending the cylinder.Using Adams simulation software,a detailed model of the lifting chassis was constructed to analyze its performance,revealing a direct correlation between the hydraulic cylinder extension and chassis elevation.Notably,the mechanism could achieve leveling on slopes with inclination angles of up to 7.5°.Comprehensive evaluations of the liftable chassis system were conducted under both static and dynamic conditions.In the static tests,the system exhibited the capacity for comprehensive or unilateral auto-leveling contingent upon the tilt,with leveling times and angular variations confined to 3.6 s and±0.4°,respectively.In dynamic tests conducted on sloped fields and paddy soils,the system reduced post-leveling mean tilt angles and standard deviations remained below 1.2°and 0.6°,respectively.These results demonstrated a substantial improvement in the stability and reliability of the chassis during operations.This research provides valuable insights into the design and optimization of automatic leveling mechanisms and structural innovations for harvester chassis.
