Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic re...Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic resin and n-octanol were used to synthesize the main agent SCA-2.Hexamethylenetetramine and vinyl carbonate were selected to prepare the curing agent YGA-1,which was then compounded with SCA-2 to develop a sand fixation and water plugging system.Firstly,single-factor experiments were conducted to determine the optimal concentrations of SCA-2 and YGA-1,subsequently,the system’s sand fixation and water blocking performance were evaluated.Finally,a pilot test was carried out in the mining site.Experimental results showed that the optimal formula composition of the system was 10%SCA-2+5%YGA-1.The gelation time of the system was 180 minutes and the viscosity after gelation could reach 108.4 mPa·s.When the dosage of the drug system was 0.6 PV,the sand production rate remained below 0.08%.Dual-tube parallel experiments showed that the sand fixation and water plugging system had a water flow channel plugging rate of 87.5%,while the oil flow channel plugging rate was only 11.3%,indicating minimal damage to the oil-bearing reservoir.The field test showed that after the measures taken in Well M of X oilfield,the sand free oil recovery period exceeded 360 days,the water content decreased by 5.0%and the cumulative oil production increased by 7092 m^(3).This study provides new ideas for efficient development of loose sandstone reservoirs.展开更多
A nonlinear multi-scale interaction(NMI)model was proposed and developed by the first author for nearly 30 years to represent the evolution of atmospheric blocking.In this review paper,we first review the creation and...A nonlinear multi-scale interaction(NMI)model was proposed and developed by the first author for nearly 30 years to represent the evolution of atmospheric blocking.In this review paper,we first review the creation and development of the NMI model and then emphasize that the NMI model represents a new tool for identifying the basic physics of how climate change influences mid-to-high latitude weather extremes.The building of the NMI model took place over three main periods.In the 1990s,a nonlinear Schr?dinger(NLS)equation model was presented to describe atmospheric blocking as a wave packet;however,it could not depict the lifetime(10-20 days)of atmospheric blocking.In the 2000s,we proposed an NMI model of atmospheric blocking in a uniform basic flow by making a scale-separation assumption and deriving an eddyforced NLS equation.This model succeeded in describing the life cycle of atmospheric blocking.In the 2020s,the NMI model was extended to include the impact of a changing climate mainly by altering the basic zonal winds and the magnitude of the meridional background potential vorticity gradient(PVy).Model results show that when PVy is smaller,blocking has a weaker dispersion and a stronger nonlinearity,so blocking can be more persistent and have a larger zonal scale and weaker eastward movement,thus favoring stronger weather extremes.However,when PVy is much smaller and below a critical threshold under much stronger winter Arctic warming of global warming,atmospheric blocking becomes locally less persistent and shows a much stronger westward movement,which acts to inhibit local cold extremes.Such a case does not happen in summer under global warming because PVy fails to fall below the critical threshold.Thus,our theory indicates that global warming can render summer-blocking anticyclones and mid-to-high latitude heatwaves more persistent,intense,and widespread.展开更多
The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical m...The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical model height.The Taguchi method was employed to establish the correlations between process parameter combinations and multi-objective characterization of metal deposition morphology(height error and roughness).Results show that using the signal-to-noise ratio and grey relational analysis,the optimal parameter combination for multi-layer and multi-pass deposition is determined as follows:laser power of 800 W,powder feeding rate of 0.3 r/min,step distance of 1.6 mm,and scanning speed of 20 mm/s.Subsequently,a Genetic Bayesian-back propagation(GB-BP)network is constructed to predict multi-objective responses.Compared with the traditional back propagation network,the GB-back propagation network improves the prediction accuracy of height error and surface roughness by 43.14%and 71.43%,respectively.This network can accurately predict the multi-objective characterization of morphological quality of multi-layer and multi-pass metal deposited parts.展开更多
Three extreme cold events occurred in eastern Asia in January 2016,January 2021,and December 2023.As important factors in atmospheric circulation anomalies,the Blocking High and East Asian Trough(BH-ET)structure playe...Three extreme cold events occurred in eastern Asia in January 2016,January 2021,and December 2023.As important factors in atmospheric circulation anomalies,the Blocking High and East Asian Trough(BH-ET)structure played key roles during these three extreme cold wave events.Among these two dynamic patterns,the BH affected the development of the cold waves in two different ways:(1)before the cold waves in 2016 and 2023,the BH pushed the cold air southward,resulting in a slow and gradual cooling,with a cooling rate(CR)in eastern Asia of 1.34℃d^(-1)and 1.2℃d^(-1),respectively,and(2)in January 2021,the sudden collapse of BH caused the cold air to rapidly attack mid-latitude regions,with a CR of 1.87℃d^(-1).In terms of the spatial CR,the temperature drop in 2021 occurred 38.8%and 55%faster than those in 2016 and 2023,respectively.At the same time,the ET influences the wind direction of cold waves by modulating the pressure gradient.Before the cold waves occurred,the meridional wind field near the ET showed negative values,forming northwesterly or northeasterly winds,which continued to affect the southern part of East Asia.The meridional wind in January 2021 was stronger than those in 2016 and 2023,which is thought to be the reason for the strength of the 2021 cold wave.Finally,results from the temperature Empirical Orthogonal Function(EOF)analysis from 1980-2023 verify an obvious BH-ET structure in the three cold wave events,which suggests that this particular climatological state provides a climatic background for the occurrence of cold waves.展开更多
Seawater is the most abundant source of molecular hydrogen.Utilizing the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservat...Seawater is the most abundant source of molecular hydrogen.Utilizing the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservation endeavors in the future.Recently,there has been a surge in study in the field addressing the production of hydrogen through the electrochemical seawater splitting.However,the performance and durability of the electrode have limitations due to the fact that there are a few challenges that need to be addressed in order to make the technology suitable for the industrial purpose.The active site blockage caused by chloride ions that are prevalent in seawater and chloride corrosion is the most significant issue;it has a negative impact on both the activity and the durability of the anode component.Addressing this particular issue is of upmost importance in the seawater splitting area.This review concentrates on the newly developed materials and techniques for inhibiting chloride ions by blocking the active sites,simultaneously preventing the chloride corrosion.It is anticipated that the concept will be advantageous for a large audience and will inspire researchers to study on this particular area of concern.展开更多
White light illumination is essential in daily life,however,the substantial amount of blue light it contains can damage human eyes.Therefore,it is important to block this high-energy blue light to protect visual healt...White light illumination is essential in daily life,however,the substantial amount of blue light it contains can damage human eyes.Therefore,it is important to block this high-energy blue light to protect visual health.In this study,yellow-emitting carbon dots(CDs)with a quantum yield exceeding 94%were synthesized using citric acid and urea.These CDs effectively absorb blue light.By incorporating them into polystyrene,multiple films termed CDs-based blue light blocking films(CBFs)were developed,each offering different levels of blue light absorption.These CBFs exhibited excellent transparency and efficient blue light filtering capabilities.This study highlights the potential of high quantum yield CDs,which specifically absorb blue light,as foundational materials for developing light-blocking solutions against highenergy short-wavelength light.展开更多
This paper investigates a distributed heterogeneous hybrid blocking flow-shop scheduling problem(DHHBFSP)designed to minimize the total tardiness and total energy consumption simultaneously,and proposes an improved pr...This paper investigates a distributed heterogeneous hybrid blocking flow-shop scheduling problem(DHHBFSP)designed to minimize the total tardiness and total energy consumption simultaneously,and proposes an improved proximal policy optimization(IPPO)method to make real-time decisions for the DHHBFSP.A multi-objective Markov decision process is modeled for the DHHBFSP,where the reward function is represented by a vector with dynamic weights instead of the common objectiverelated scalar value.A factory agent(FA)is formulated for each factory to select unscheduled jobs and is trained by the proposed IPPO to improve the decision quality.Multiple FAs work asynchronously to allocate jobs that arrive randomly at the shop.A two-stage training strategy is introduced in the IPPO,which learns from both single-and dual-policy data for better data utilization.The proposed IPPO is tested on randomly generated instances and compared with variants of the basic proximal policy optimization(PPO),dispatch rules,multi-objective metaheuristics,and multi-agent reinforcement learning methods.Extensive experimental results suggest that the proposed strategies offer significant improvements to the basic PPO,and the proposed IPPO outperforms the state-of-the-art scheduling methods in both convergence and solution quality.展开更多
BACKGROUND A major cause of mortality in the coronavirus disease 2019(COVID-19)pandemic was acute respiratory distress syndrome(ARDS).Currently,moderate to severe ARDS induced by COVID-19(COVID ARDS)and other viral an...BACKGROUND A major cause of mortality in the coronavirus disease 2019(COVID-19)pandemic was acute respiratory distress syndrome(ARDS).Currently,moderate to severe ARDS induced by COVID-19(COVID ARDS)and other viral and non-viral etiologies are treated by traditional ARDS protocols that recommend 12-16 hours of prone position ventilation(PPV)with neuromuscular blocking agents(NMBA)and a trial of inhaled vasodilators(IVd)if oxygenation does not improve.However,debate on the efficacy of adjuncts to PPV and low tidal volume ventilation persists and evidence about the benefits of IVd/NMBA in COVID ARDS is sparse.In our multi-center retrospective review,we evaluated the impact of PPV,IVd,and NMBA on outcomes and lung mechanics in COVID ARDS patients with moderate to severe ARDS.AIM To evaluate the impact of PPV used alone or in combination with pulmonary IVd and/or NMBA in mechanically ventilated patients with moderate to severe ARDS during the COVID-19 pandemic.METHODS A retrospective study at two tertiary academic medical centers compared outcomes between COVID ARDS patients receiving PPV and patients in the supine position.PPV patients were divided based on concurrent use of ARDS adjunct therapies resulting in four subgroups:(1)PPV alone;(2)PPV and IVd;(3)PPV and NMBA;and(4)PPV,IVd,and NMBA.Primary outcomes were hospital and intensive care unit(ICU)length of stay(LOS),mortality,and venovenous extracorporeal membrane oxygenation(VV-ECMO)status.Secondary outcomes included changes in lung mechanics at 24-hour intervals for 7 days.RESULTS Total 114 patients were included in this study.Baseline respiratory parameters and Sequential Organ Failure Assessment scores were significantly worse in the PPV group.ICU LOS and LOS were significantly longer for patients who were proned,but no mortality benefit or difference in VV-ECMO status was found.Among the subgroups,no difference in primary outcomes were found.In the secondary analysis,PPV was associated with a significant improvement in arterial oxygen partial pressure(PaO_(2))/fractional inspired oxygen(FiO_(2))(P/F)ratio from day 1 to day 4(P<0.05)and higher driving pressures day 5 to day 7(P<0.05).The combination of PPV and IVd together resulted in improvements in P/F ratio from day 1 to day 7 and plateau pressure on day 4 and day 6(P<0.05).PPV with NMBA was not associated with improvements in any of the secondary outcomes.The use of all three rescue therapies together resulted in improvements in lung compliance on day 2(P<0.05)but no other improvements.CONCLUSION In mechanically ventilated patients diagnosed with moderate to severe COVID ARDS,PPV and PPV with the addition of IVd produced a significant and sustained increase in P/F ratio.The combination of PPV,IVd and NMBA improved compliance however this did not reach significance.Mortality and LOS did not improve with adjunct therapies.Further research is warranted to determine the efficacy of these therapies alone and in combination in the treatment of COVID ARDS.展开更多
Some novel techniques of computational fluid dynamics are used to establish a mathematical model for the open diversion channel with two embankments in river blocking.The technique of boundary fitted coordinate syste...Some novel techniques of computational fluid dynamics are used to establish a mathematical model for the open diversion channel with two embankments in river blocking.The technique of boundary fitted coordinate system is used to overcome the difficulties resulting from the complicated shapes of natural river boundaries;the method of alternating direction implicit finite difference scheme is used to solve the partial differential equations in the transformed plane;and the technique of moving boundary is used to deal with the river bed exposed to water surface.This model has been used to predict the flow characteristics in the blocking of the Yangtz river in the Three Gorge Project (TGP).Comparison between the computed and experimental data shows a satisfactory agreement.展开更多
Objective To observe the analgesic effect on herpes zoster treated by the comprehensive therapy of blocking, surrounding needling, pricking and cupping combined with bloodletting at Longyan （龙眼, Extra） acupoint. M...Objective To observe the analgesic effect on herpes zoster treated by the comprehensive therapy of blocking, surrounding needling, pricking and cupping combined with bloodletting at Longyan （龙眼, Extra） acupoint. Methods According to the random mumber table, 104 cases of herpes zoster were randomized into an observation group and a control group, 52 cases in each one. In the observation group, the blocking method was used at the starting site and the ending site of herpetic zone, the surrounding needling method was applied toward the center of the painful zone, with horizontal needling technique; and the local pricking and cupping methods as well as the bloodletting at Longyan （Extra） acupoint were adopted. In the control group, Jiáj （夹脊 EX-B 2） at the corresponding affected nerve segments and the local Ashi points were selected and stimulated with electroacupuncture. The visual analogue scale （VAS） was adopted to determine the analgesic effect 20 min, 1, 6, 12, 24 and 48 h after treatment separately in each group. Results The onset time of analgesic effect in the observation group was shorter than that in the control group and the efficacy time of duration was longer than that in the control group （all P0.05）. The analgesic effect and the result of comprehensive efficacy assessment were superior to those of the control group （both P0.05）. Conclusion The comprehensive therapy of blocking, surrounding needling, pricking and cupping method combined with bloodletting at Longyan （Extra） achieves the significant analgesic effect on herpes zoster.展开更多
With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided m...With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.展开更多
AIM:To investigate effects of perirenal space blocking(PSB)on gastrointestinal function in patients with severe acute pancreatitis(SAP).METHODS:Forty patients with SAP were randomly allocated to receive PSB or no PSB(...AIM:To investigate effects of perirenal space blocking(PSB)on gastrointestinal function in patients with severe acute pancreatitis(SAP).METHODS:Forty patients with SAP were randomly allocated to receive PSB or no PSB(NPSB).All the SAP patients received specialized medical therapy(SMT).Patients in the PSB group received PSB+SMT when hospitalized and after diagnosis,whereas patients in the NPSB group only received SMT.A modifed gastrointestinal failure(GIF)scoring system was used to assess the gastrointestinal function in SAP patients after admission.Pain severity(visual analog scale,0 to100)was monitored every 24 h for 72 h.RESULTS:Modified GIF score decreased in both groups during the 10-d study period.The median score decrease was initially significantly greater in the PSB group than in the NPSB group after PSB was per-formed.During the 72-h study period,pain intensity decreased in both groups.The median pain decrease was significantly greater in the PSB group than in the NPSB group at single time points.Patients in the PSB group had significantly lower incidences of hospital mortality,multiple organ dysfunction syndrome,systemic inflammatory response syndrome,and pancreatic infection,and stayed in the intensive care unit for a shorter duration.However,no difference in terms of operation incidence was found between the two groups.CONCLUSION:PSB could ameliorate gastrointestinal dysfunction or failure during the early stage of SAP.Moreover,PSB administration could improve prognosis and decrease the mortality of SAP patients.展开更多
In this paper, a new transient forced quasi-resonant triad interaction theory in a beta channel is proposed to investigate the interaction between planetary-scale diffluent flow composed of zonal wavenumbers 1-3 and s...In this paper, a new transient forced quasi-resonant triad interaction theory in a beta channel is proposed to investigate the interaction between planetary-scale diffluent flow composed of zonal wavenumbers 1-3 and synoptic-scale waves produced continuously by a synoptic-scale vorticity source fixed upstream of an incipient blocking region during the life cycle of blocking. It is shown that the superposition of initial three Rossby waves for zonal wavenumbers 1 （monopole）, 2 （dipole）, and 3 （monopole）, which permit triad quasi-resonance, can represent an incipient blocking event. The synoptic-scale eddies may act to amplify the incipient blocking and to excite a blocking circulation with a strong meander, whose flow pattern depends on the initial amplitudes of the planetary waves and both the intensity and location of preexisting synoptic-scale waves. The onset （decay） of the planetary-scale split-flow blocking is mainly represented by a strong increase （decrease） in the amplitude of the zonal wavenumber 2 component, having a dipole meridional structure related to the preexisting synoptic-scale eddies. The typical persistence time of the model blocking was of about 20 days, consistent with observations of blocking patterns. In our model, isolated asymmetric dipole blocking is formed by synoptic-scale waves. The instantaneous fields of total streamfunctions exhibit a remarkable resemblance to the synoptic maps observed during the life cycle of blocking. During the onset stage, the synoptic-scale waves are enhanced and split into two branches around the blocking region due to the feedback of the amplified blocking, in agreement with the observed changes of synoptic-scale waves in real blocking events. In addition, a diagnostic case study of blocking is presented to confirm the forced quasi-resonant triad interaction theory proposed here.展开更多
In this paper, in an equivalent barotropic framework a new forced nonlinear Schroedinger equation is proposed to examine the interaction between the planetary-scale waves and the localized synoptic-scale eddies upstre...In this paper, in an equivalent barotropic framework a new forced nonlinear Schroedinger equation is proposed to examine the interaction between the planetary-scale waves and the localized synoptic-scale eddies upstream. With the help of the perturbed inverse scattering transform method, nonlinear parameter equations can be derived to describe the evolution of the dipole soliton amplitude, frequency, group velocity and phase under the forcing of localized synoptic-scale eddies. The numerical solutions of these equations predict that in the interaction between the weak dipole soliton (weak incipient dipole anomaly) and the synoptic-scale eddies, only when the high-frequency eddies themselves have a moderate parameter match they can near resonantly enhance a quasi-stationary large-amplitude split flow. The instantaneous total streamfunction field (the sum of background westerly wind, envelope Rossby soliton and synoptic-scale waves) is found to be very similar to the observed Berggren-type blocking on the weather map(Berggren et al. 1949). The role of synoptic-scale eddies is to increase the amplitude of large-scale dipole anomaly flow, and to decrease its group velocity, phase velocity and zonal wavenumber so that the dipole anomaly system can be amplified and transferred from dispersive system to very weak dispersive one. This may explain why and how the synoptic-scale eddies can reinforce and maintain vortex pair block. Furthermore, it is clearly found that during the prevalence of the vortex pair block the synoptic-scale eddies are split into two branches around the vortex pair block due to the feedback of amplified dipole block. Key words Envelope Rossby solilon - Blocking - Synoptic-to-planetary scale interaction This research was supported jointly by the Foundation for University Key Teacher by the Ministry of Education and by the National Natural Science Foundation of China (49775266, 49905007)), the Knowledge Innovation Key Project of Chinese Academy of Sciences in the Resource Environment Field (Grant No. KZCX 2-203) and the National Key Foundation Research Project (G1998040900, Part I).展开更多
Using cesium lead halide perovskite nanocrystals, CsPb(Cl/Br)3, as a light absorber, we report a highly effective UV and blue light blocking film. The CsPb(Cl/Br)3 nanocrystals are well dispersed in the ethyl cellulos...Using cesium lead halide perovskite nanocrystals, CsPb(Cl/Br)3, as a light absorber, we report a highly effective UV and blue light blocking film. The CsPb(Cl/Br)3 nanocrystals are well dispersed in the ethyl cellulose(EC) matrix to compose a UV and blue light shielding film, and the absorption edge of the film is tunable by adjusting Cl to Br ratio using anion exchange. The CsPbCl2 Br-EC film exhibits a transmittance of 5% at 459 nm, 90% at 478 nm and 95% in the range of 500–800 nm, which makes it excellent for UV and blue light shielding. In addition, the as-prepared EC-CsPb(Cl/Br)3 film shows excellent photostability under UV irradiation. Results demonstrate that this EC-CsPb(Cl/Br)3 based materials with sharp absorbance edges, tunable blocking wavelength, and high photostability can be useful for the applications in UV and blue light blocking and optical filters.展开更多
The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributi...The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributions of the SST anomalies in the tropical western Pacific,respectively.Firstly,the atmospheric circulation anomalies during July and August,1980 are simulated by three anomalous experiments including the global SST anomaly experiment,the tropical SST anomaly experiment and the extratropical SST anomaly experiment,using the observed SST anomalies in 1980.It is shown that the SST anomalies in the tropical ocean greatly influence the formation and maintenance of the blocking high over the northeastern Asia,and may play a more important role than the SST anomalies in the extratropical ocean in the influence on the atmospheric circulation anomalies.Secondly,the effects of the SST anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are also simulated with an idealized distribution of the SST anomalies in the tropical western Pacific.The simulated results show that the negative anomalies of SST in the tropical western Pacific have a significant effect on the formation and maintenance of the blocking high over the northeastern Asia.展开更多
文摘Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic resin and n-octanol were used to synthesize the main agent SCA-2.Hexamethylenetetramine and vinyl carbonate were selected to prepare the curing agent YGA-1,which was then compounded with SCA-2 to develop a sand fixation and water plugging system.Firstly,single-factor experiments were conducted to determine the optimal concentrations of SCA-2 and YGA-1,subsequently,the system’s sand fixation and water blocking performance were evaluated.Finally,a pilot test was carried out in the mining site.Experimental results showed that the optimal formula composition of the system was 10%SCA-2+5%YGA-1.The gelation time of the system was 180 minutes and the viscosity after gelation could reach 108.4 mPa·s.When the dosage of the drug system was 0.6 PV,the sand production rate remained below 0.08%.Dual-tube parallel experiments showed that the sand fixation and water plugging system had a water flow channel plugging rate of 87.5%,while the oil flow channel plugging rate was only 11.3%,indicating minimal damage to the oil-bearing reservoir.The field test showed that after the measures taken in Well M of X oilfield,the sand free oil recovery period exceeded 360 days,the water content decreased by 5.0%and the cumulative oil production increased by 7092 m^(3).This study provides new ideas for efficient development of loose sandstone reservoirs.
基金supported by the National Natural Science Foundation of China(Grant Nos.42150204 and 2288101)supported by the China National Postdoctoral Program for Innovative Talents(BX20230045)the China Postdoctoral Science Foundation(2023M730279)。
文摘A nonlinear multi-scale interaction(NMI)model was proposed and developed by the first author for nearly 30 years to represent the evolution of atmospheric blocking.In this review paper,we first review the creation and development of the NMI model and then emphasize that the NMI model represents a new tool for identifying the basic physics of how climate change influences mid-to-high latitude weather extremes.The building of the NMI model took place over three main periods.In the 1990s,a nonlinear Schr?dinger(NLS)equation model was presented to describe atmospheric blocking as a wave packet;however,it could not depict the lifetime(10-20 days)of atmospheric blocking.In the 2000s,we proposed an NMI model of atmospheric blocking in a uniform basic flow by making a scale-separation assumption and deriving an eddyforced NLS equation.This model succeeded in describing the life cycle of atmospheric blocking.In the 2020s,the NMI model was extended to include the impact of a changing climate mainly by altering the basic zonal winds and the magnitude of the meridional background potential vorticity gradient(PVy).Model results show that when PVy is smaller,blocking has a weaker dispersion and a stronger nonlinearity,so blocking can be more persistent and have a larger zonal scale and weaker eastward movement,thus favoring stronger weather extremes.However,when PVy is much smaller and below a critical threshold under much stronger winter Arctic warming of global warming,atmospheric blocking becomes locally less persistent and shows a much stronger westward movement,which acts to inhibit local cold extremes.Such a case does not happen in summer under global warming because PVy fails to fall below the critical threshold.Thus,our theory indicates that global warming can render summer-blocking anticyclones and mid-to-high latitude heatwaves more persistent,intense,and widespread.
基金National Natural Science Foundation of China(52175237)。
文摘The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical model height.The Taguchi method was employed to establish the correlations between process parameter combinations and multi-objective characterization of metal deposition morphology(height error and roughness).Results show that using the signal-to-noise ratio and grey relational analysis,the optimal parameter combination for multi-layer and multi-pass deposition is determined as follows:laser power of 800 W,powder feeding rate of 0.3 r/min,step distance of 1.6 mm,and scanning speed of 20 mm/s.Subsequently,a Genetic Bayesian-back propagation(GB-BP)network is constructed to predict multi-objective responses.Compared with the traditional back propagation network,the GB-back propagation network improves the prediction accuracy of height error and surface roughness by 43.14%and 71.43%,respectively.This network can accurately predict the multi-objective characterization of morphological quality of multi-layer and multi-pass metal deposited parts.
基金supported by the National Natural Science Foundation of China under Grant No.41821004,the National Key Research and Development Program of China under contract No.2022YFE0140500the National Key R&D Program of China under contract No.2022YFA1004403+2 种基金the Laoshan Laboratory Science and Technology Innovation Project No.LSKJ202202104the National Nature Science Foundation of China No.42130406the Project of Doctoral Found of Qingdao University of Science and Technology under contract No.210010022746.
文摘Three extreme cold events occurred in eastern Asia in January 2016,January 2021,and December 2023.As important factors in atmospheric circulation anomalies,the Blocking High and East Asian Trough(BH-ET)structure played key roles during these three extreme cold wave events.Among these two dynamic patterns,the BH affected the development of the cold waves in two different ways:(1)before the cold waves in 2016 and 2023,the BH pushed the cold air southward,resulting in a slow and gradual cooling,with a cooling rate(CR)in eastern Asia of 1.34℃d^(-1)and 1.2℃d^(-1),respectively,and(2)in January 2021,the sudden collapse of BH caused the cold air to rapidly attack mid-latitude regions,with a CR of 1.87℃d^(-1).In terms of the spatial CR,the temperature drop in 2021 occurred 38.8%and 55%faster than those in 2016 and 2023,respectively.At the same time,the ET influences the wind direction of cold waves by modulating the pressure gradient.Before the cold waves occurred,the meridional wind field near the ET showed negative values,forming northwesterly or northeasterly winds,which continued to affect the southern part of East Asia.The meridional wind in January 2021 was stronger than those in 2016 and 2023,which is thought to be the reason for the strength of the 2021 cold wave.Finally,results from the temperature Empirical Orthogonal Function(EOF)analysis from 1980-2023 verify an obvious BH-ET structure in the three cold wave events,which suggests that this particular climatological state provides a climatic background for the occurrence of cold waves.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2024-00436563)supported by Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea(Grant No.RS-2023-00284361).
文摘Seawater is the most abundant source of molecular hydrogen.Utilizing the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservation endeavors in the future.Recently,there has been a surge in study in the field addressing the production of hydrogen through the electrochemical seawater splitting.However,the performance and durability of the electrode have limitations due to the fact that there are a few challenges that need to be addressed in order to make the technology suitable for the industrial purpose.The active site blockage caused by chloride ions that are prevalent in seawater and chloride corrosion is the most significant issue;it has a negative impact on both the activity and the durability of the anode component.Addressing this particular issue is of upmost importance in the seawater splitting area.This review concentrates on the newly developed materials and techniques for inhibiting chloride ions by blocking the active sites,simultaneously preventing the chloride corrosion.It is anticipated that the concept will be advantageous for a large audience and will inspire researchers to study on this particular area of concern.
基金supported by Medical Science and Technology Research Project of Henan Province(Joint Construction Project)(No.LHGJ20200433)National Natural Science Foundation of China(No.52122308)。
文摘White light illumination is essential in daily life,however,the substantial amount of blue light it contains can damage human eyes.Therefore,it is important to block this high-energy blue light to protect visual health.In this study,yellow-emitting carbon dots(CDs)with a quantum yield exceeding 94%were synthesized using citric acid and urea.These CDs effectively absorb blue light.By incorporating them into polystyrene,multiple films termed CDs-based blue light blocking films(CBFs)were developed,each offering different levels of blue light absorption.These CBFs exhibited excellent transparency and efficient blue light filtering capabilities.This study highlights the potential of high quantum yield CDs,which specifically absorb blue light,as foundational materials for developing light-blocking solutions against highenergy short-wavelength light.
基金partially supported by the National Key Research and Development Program of the Ministry of Science and Technology of China(2022YFE0114200)the National Natural Science Foundation of China(U20A6004).
文摘This paper investigates a distributed heterogeneous hybrid blocking flow-shop scheduling problem(DHHBFSP)designed to minimize the total tardiness and total energy consumption simultaneously,and proposes an improved proximal policy optimization(IPPO)method to make real-time decisions for the DHHBFSP.A multi-objective Markov decision process is modeled for the DHHBFSP,where the reward function is represented by a vector with dynamic weights instead of the common objectiverelated scalar value.A factory agent(FA)is formulated for each factory to select unscheduled jobs and is trained by the proposed IPPO to improve the decision quality.Multiple FAs work asynchronously to allocate jobs that arrive randomly at the shop.A two-stage training strategy is introduced in the IPPO,which learns from both single-and dual-policy data for better data utilization.The proposed IPPO is tested on randomly generated instances and compared with variants of the basic proximal policy optimization(PPO),dispatch rules,multi-objective metaheuristics,and multi-agent reinforcement learning methods.Extensive experimental results suggest that the proposed strategies offer significant improvements to the basic PPO,and the proposed IPPO outperforms the state-of-the-art scheduling methods in both convergence and solution quality.
文摘BACKGROUND A major cause of mortality in the coronavirus disease 2019(COVID-19)pandemic was acute respiratory distress syndrome(ARDS).Currently,moderate to severe ARDS induced by COVID-19(COVID ARDS)and other viral and non-viral etiologies are treated by traditional ARDS protocols that recommend 12-16 hours of prone position ventilation(PPV)with neuromuscular blocking agents(NMBA)and a trial of inhaled vasodilators(IVd)if oxygenation does not improve.However,debate on the efficacy of adjuncts to PPV and low tidal volume ventilation persists and evidence about the benefits of IVd/NMBA in COVID ARDS is sparse.In our multi-center retrospective review,we evaluated the impact of PPV,IVd,and NMBA on outcomes and lung mechanics in COVID ARDS patients with moderate to severe ARDS.AIM To evaluate the impact of PPV used alone or in combination with pulmonary IVd and/or NMBA in mechanically ventilated patients with moderate to severe ARDS during the COVID-19 pandemic.METHODS A retrospective study at two tertiary academic medical centers compared outcomes between COVID ARDS patients receiving PPV and patients in the supine position.PPV patients were divided based on concurrent use of ARDS adjunct therapies resulting in four subgroups:(1)PPV alone;(2)PPV and IVd;(3)PPV and NMBA;and(4)PPV,IVd,and NMBA.Primary outcomes were hospital and intensive care unit(ICU)length of stay(LOS),mortality,and venovenous extracorporeal membrane oxygenation(VV-ECMO)status.Secondary outcomes included changes in lung mechanics at 24-hour intervals for 7 days.RESULTS Total 114 patients were included in this study.Baseline respiratory parameters and Sequential Organ Failure Assessment scores were significantly worse in the PPV group.ICU LOS and LOS were significantly longer for patients who were proned,but no mortality benefit or difference in VV-ECMO status was found.Among the subgroups,no difference in primary outcomes were found.In the secondary analysis,PPV was associated with a significant improvement in arterial oxygen partial pressure(PaO_(2))/fractional inspired oxygen(FiO_(2))(P/F)ratio from day 1 to day 4(P<0.05)and higher driving pressures day 5 to day 7(P<0.05).The combination of PPV and IVd together resulted in improvements in P/F ratio from day 1 to day 7 and plateau pressure on day 4 and day 6(P<0.05).PPV with NMBA was not associated with improvements in any of the secondary outcomes.The use of all three rescue therapies together resulted in improvements in lung compliance on day 2(P<0.05)but no other improvements.CONCLUSION In mechanically ventilated patients diagnosed with moderate to severe COVID ARDS,PPV and PPV with the addition of IVd produced a significant and sustained increase in P/F ratio.The combination of PPV,IVd and NMBA improved compliance however this did not reach significance.Mortality and LOS did not improve with adjunct therapies.Further research is warranted to determine the efficacy of these therapies alone and in combination in the treatment of COVID ARDS.
文摘Some novel techniques of computational fluid dynamics are used to establish a mathematical model for the open diversion channel with two embankments in river blocking.The technique of boundary fitted coordinate system is used to overcome the difficulties resulting from the complicated shapes of natural river boundaries;the method of alternating direction implicit finite difference scheme is used to solve the partial differential equations in the transformed plane;and the technique of moving boundary is used to deal with the river bed exposed to water surface.This model has been used to predict the flow characteristics in the blocking of the Yangtz river in the Three Gorge Project (TGP).Comparison between the computed and experimental data shows a satisfactory agreement.
文摘Objective To observe the analgesic effect on herpes zoster treated by the comprehensive therapy of blocking, surrounding needling, pricking and cupping combined with bloodletting at Longyan （龙眼, Extra） acupoint. Methods According to the random mumber table, 104 cases of herpes zoster were randomized into an observation group and a control group, 52 cases in each one. In the observation group, the blocking method was used at the starting site and the ending site of herpetic zone, the surrounding needling method was applied toward the center of the painful zone, with horizontal needling technique; and the local pricking and cupping methods as well as the bloodletting at Longyan （Extra） acupoint were adopted. In the control group, Jiáj （夹脊 EX-B 2） at the corresponding affected nerve segments and the local Ashi points were selected and stimulated with electroacupuncture. The visual analogue scale （VAS） was adopted to determine the analgesic effect 20 min, 1, 6, 12, 24 and 48 h after treatment separately in each group. Results The onset time of analgesic effect in the observation group was shorter than that in the control group and the efficacy time of duration was longer than that in the control group （all P0.05）. The analgesic effect and the result of comprehensive efficacy assessment were superior to those of the control group （both P0.05）. Conclusion The comprehensive therapy of blocking, surrounding needling, pricking and cupping method combined with bloodletting at Longyan （Extra） achieves the significant analgesic effect on herpes zoster.
基金the Indian Institute of Technology Bombay’s Post-Doctoral Research Program, vide appointment no. AO/Admn1/33/2018 dated 10.Aug’2018 for providing funding
文摘With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.
文摘AIM:To investigate effects of perirenal space blocking(PSB)on gastrointestinal function in patients with severe acute pancreatitis(SAP).METHODS:Forty patients with SAP were randomly allocated to receive PSB or no PSB(NPSB).All the SAP patients received specialized medical therapy(SMT).Patients in the PSB group received PSB+SMT when hospitalized and after diagnosis,whereas patients in the NPSB group only received SMT.A modifed gastrointestinal failure(GIF)scoring system was used to assess the gastrointestinal function in SAP patients after admission.Pain severity(visual analog scale,0 to100)was monitored every 24 h for 72 h.RESULTS:Modified GIF score decreased in both groups during the 10-d study period.The median score decrease was initially significantly greater in the PSB group than in the NPSB group after PSB was per-formed.During the 72-h study period,pain intensity decreased in both groups.The median pain decrease was significantly greater in the PSB group than in the NPSB group at single time points.Patients in the PSB group had significantly lower incidences of hospital mortality,multiple organ dysfunction syndrome,systemic inflammatory response syndrome,and pancreatic infection,and stayed in the intensive care unit for a shorter duration.However,no difference in terms of operation incidence was found between the two groups.CONCLUSION:PSB could ameliorate gastrointestinal dysfunction or failure during the early stage of SAP.Moreover,PSB administration could improve prognosis and decrease the mortality of SAP patients.
基金supported in part by the National Natural Science Fundation of China(Grant No. 4057016)and Taishan Scholar funding
文摘In this paper, a new transient forced quasi-resonant triad interaction theory in a beta channel is proposed to investigate the interaction between planetary-scale diffluent flow composed of zonal wavenumbers 1-3 and synoptic-scale waves produced continuously by a synoptic-scale vorticity source fixed upstream of an incipient blocking region during the life cycle of blocking. It is shown that the superposition of initial three Rossby waves for zonal wavenumbers 1 （monopole）, 2 （dipole）, and 3 （monopole）, which permit triad quasi-resonance, can represent an incipient blocking event. The synoptic-scale eddies may act to amplify the incipient blocking and to excite a blocking circulation with a strong meander, whose flow pattern depends on the initial amplitudes of the planetary waves and both the intensity and location of preexisting synoptic-scale waves. The onset （decay） of the planetary-scale split-flow blocking is mainly represented by a strong increase （decrease） in the amplitude of the zonal wavenumber 2 component, having a dipole meridional structure related to the preexisting synoptic-scale eddies. The typical persistence time of the model blocking was of about 20 days, consistent with observations of blocking patterns. In our model, isolated asymmetric dipole blocking is formed by synoptic-scale waves. The instantaneous fields of total streamfunctions exhibit a remarkable resemblance to the synoptic maps observed during the life cycle of blocking. During the onset stage, the synoptic-scale waves are enhanced and split into two branches around the blocking region due to the feedback of the amplified blocking, in agreement with the observed changes of synoptic-scale waves in real blocking events. In addition, a diagnostic case study of blocking is presented to confirm the forced quasi-resonant triad interaction theory proposed here.
基金This research was supported jointly by the Foundation for University Key Teacher by the Ministry ofEducation and by the Nation
文摘In this paper, in an equivalent barotropic framework a new forced nonlinear Schroedinger equation is proposed to examine the interaction between the planetary-scale waves and the localized synoptic-scale eddies upstream. With the help of the perturbed inverse scattering transform method, nonlinear parameter equations can be derived to describe the evolution of the dipole soliton amplitude, frequency, group velocity and phase under the forcing of localized synoptic-scale eddies. The numerical solutions of these equations predict that in the interaction between the weak dipole soliton (weak incipient dipole anomaly) and the synoptic-scale eddies, only when the high-frequency eddies themselves have a moderate parameter match they can near resonantly enhance a quasi-stationary large-amplitude split flow. The instantaneous total streamfunction field (the sum of background westerly wind, envelope Rossby soliton and synoptic-scale waves) is found to be very similar to the observed Berggren-type blocking on the weather map(Berggren et al. 1949). The role of synoptic-scale eddies is to increase the amplitude of large-scale dipole anomaly flow, and to decrease its group velocity, phase velocity and zonal wavenumber so that the dipole anomaly system can be amplified and transferred from dispersive system to very weak dispersive one. This may explain why and how the synoptic-scale eddies can reinforce and maintain vortex pair block. Furthermore, it is clearly found that during the prevalence of the vortex pair block the synoptic-scale eddies are split into two branches around the vortex pair block due to the feedback of amplified dipole block. Key words Envelope Rossby solilon - Blocking - Synoptic-to-planetary scale interaction This research was supported jointly by the Foundation for University Key Teacher by the Ministry of Education and by the National Natural Science Foundation of China (49775266, 49905007)), the Knowledge Innovation Key Project of Chinese Academy of Sciences in the Resource Environment Field (Grant No. KZCX 2-203) and the National Key Foundation Research Project (G1998040900, Part I).
基金financially supported by the National Nature Scientific Foundation of China(No.21675133)and OESACLS201902
文摘Using cesium lead halide perovskite nanocrystals, CsPb(Cl/Br)3, as a light absorber, we report a highly effective UV and blue light blocking film. The CsPb(Cl/Br)3 nanocrystals are well dispersed in the ethyl cellulose(EC) matrix to compose a UV and blue light shielding film, and the absorption edge of the film is tunable by adjusting Cl to Br ratio using anion exchange. The CsPbCl2 Br-EC film exhibits a transmittance of 5% at 459 nm, 90% at 478 nm and 95% in the range of 500–800 nm, which makes it excellent for UV and blue light shielding. In addition, the as-prepared EC-CsPb(Cl/Br)3 film shows excellent photostability under UV irradiation. Results demonstrate that this EC-CsPb(Cl/Br)3 based materials with sharp absorbance edges, tunable blocking wavelength, and high photostability can be useful for the applications in UV and blue light blocking and optical filters.
基金This study was supported by the major applied project 'KY85-10' of Chinese Academy of Sciences
文摘The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributions of the SST anomalies in the tropical western Pacific,respectively.Firstly,the atmospheric circulation anomalies during July and August,1980 are simulated by three anomalous experiments including the global SST anomaly experiment,the tropical SST anomaly experiment and the extratropical SST anomaly experiment,using the observed SST anomalies in 1980.It is shown that the SST anomalies in the tropical ocean greatly influence the formation and maintenance of the blocking high over the northeastern Asia,and may play a more important role than the SST anomalies in the extratropical ocean in the influence on the atmospheric circulation anomalies.Secondly,the effects of the SST anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are also simulated with an idealized distribution of the SST anomalies in the tropical western Pacific.The simulated results show that the negative anomalies of SST in the tropical western Pacific have a significant effect on the formation and maintenance of the blocking high over the northeastern Asia.
