This study aims to investigate the effects of different mapping unit scales and study area scales on the uncertainty rules of landslide susceptibility prediction(LSP).To illustrate various study area scales,Ganzhou Ci...This study aims to investigate the effects of different mapping unit scales and study area scales on the uncertainty rules of landslide susceptibility prediction(LSP).To illustrate various study area scales,Ganzhou City in China,its eastern region(Ganzhou East),and Ruijin County in Ganzhou East were chosen.Different mapping unit scales are represented by grid units with spatial resolution of 30 and 60 m,as well as slope units that were extracted by multi-scale segmentation method.The 3855 landslide locations and 21 typical environmental factors in Ganzhou City are first determined to create spatial datasets with input-outputs.Then,landslide susceptibility maps(LSMs)of Ganzhou City,Ganzhou East and Ruijin County are pro-duced using a support vector machine(SVM)and random forest(RF),respectively.The LSMs of the above three regions are then extracted by mask from the LSM of Ganzhou City,along with the LSMs of Ruijin County from Ganzhou East.Additionally,LSMs of Ruijin at various mapping unit scales are generated in accordance.Accuracy and landslide suscepti-bility indexes(LSIs)distribution are used to express LSP uncertainties.The LSP uncertainties under grid units significantly decrease as study area scales decrease from Ganzhou City,Ganzhou East to Ruijin County,whereas those under slope units are less affected by study area scales.Of course,attentions should also be paid to the broader representativeness of large study areas.The LSP accuracy of slope units increases by about 6%–10%compared with those under grid units with 30 m and 60 m resolution in the same study area's scale.The significance of environmental factors exhibits an averaging trend as study area scale increases from small to large.The importance of environmental factors varies greatly with the 60 m grid unit,but it tends to be consistent to some extent in the 30 m grid unit and the slope unit.展开更多
In this editorial,we comment on the article by Wang and Long,published in a recent issue of the World Journal of Clinical Cases.The article addresses the challenge of predicting intensive care unit-acquired weakness(I...In this editorial,we comment on the article by Wang and Long,published in a recent issue of the World Journal of Clinical Cases.The article addresses the challenge of predicting intensive care unit-acquired weakness(ICUAW),a neuromuscular disorder affecting critically ill patients,by employing a novel processing strategy based on repeated machine learning.The editorial presents a dataset comprising clinical,demographic,and laboratory variables from intensive care unit(ICU)patients and employs a multilayer perceptron neural network model to predict ICUAW.The authors also performed a feature importance analysis to identify the most relevant risk factors for ICUAW.This editorial contributes to the growing body of literature on predictive modeling in critical care,offering insights into the potential of machine learning approaches to improve patient outcomes and guide clinical decision-making in the ICU setting.展开更多
Intensive care unit-acquired weakness(ICU-AW)significantly hampers patient recovery and increases morbidity.With the absence of established preventive strategies,this study utilizes advanced machine learning methodolo...Intensive care unit-acquired weakness(ICU-AW)significantly hampers patient recovery and increases morbidity.With the absence of established preventive strategies,this study utilizes advanced machine learning methodologies to unearth key predictors of ICU-AW.Employing a sophisticated multilayer perceptron neural network,the research methodically assesses the predictive power for ICU-AW,pinpointing the length of ICU stay and duration of mechanical ventilation as pivotal risk factors.The findings advocate for minimizing these elements as a preventive approach,offering a novel perspective on combating ICU-AW.This research illuminates critical risk factors and lays the groundwork for future explorations into effective prevention and intervention strategies.展开更多
Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell...Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway.展开更多
Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss pos...Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios.展开更多
The neurovascular unit and stem cell therapy in ischemic stroke:Ischemic stroke,accounts for approximately 85% of all stroke incidents and is a major global health burden.It is the leading cause of disability and deat...The neurovascular unit and stem cell therapy in ischemic stroke:Ischemic stroke,accounts for approximately 85% of all stroke incidents and is a major global health burden.It is the leading cause of disability and death worldwide,posing immense societal and economic challenges due to the long-term care required for stro ke survivors and the significant healthcare costs associated with its treatment and management(Amarenco et al.,2009).展开更多
Static Poisson’s ratio(vs)is crucial for determining geomechanical properties in petroleum applications,namely sand production.Some models have been used to predict vs;however,the published models were limited to spe...Static Poisson’s ratio(vs)is crucial for determining geomechanical properties in petroleum applications,namely sand production.Some models have been used to predict vs;however,the published models were limited to specific data ranges with an average absolute percentage relative error(AAPRE)of more than 10%.The published gated recurrent unit(GRU)models do not consider trend analysis to show physical behaviors.In this study,we aim to develop a GRU model using trend analysis and three inputs for predicting n s based on a broad range of data,n s(value of 0.1627-0.4492),bulk formation density(RHOB)(0.315-2.994 g/mL),compressional time(DTc)(44.43-186.9 μs/ft),and shear time(DTs)(72.9-341.2μ s/ft).The GRU model was evaluated using different approaches,including statistical error an-alyses.The GRU model showed the proper trends,and the model data ranges were wider than previous ones.The GRU model has the largest correlation coefficient(R)of 0.967 and the lowest AAPRE,average percent relative error(APRE),root mean square error(RMSE),and standard deviation(SD)of 3.228%,1.054%,4.389,and 0.013,respectively,compared to other models.The GRU model has a high accuracy for the different datasets:training,validation,testing,and the whole datasets with R and AAPRE values were 0.981 and 2.601%,0.966 and 3.274%,0.967 and 3.228%,and 0.977 and 2.861%,respectively.The group error analyses of all inputs show that the GRU model has less than 5% AAPRE for all input ranges,which is superior to other models that have different AAPRE values of more than 10% at various ranges of inputs.展开更多
In this paper,we investigate sufficient and necessary conditions such that generalized Forelli-Rudin type operators T_(λ,τ,k),S_(λ,τ,k),Q_(λ,τ,k)and R_(λ,τ,k)are bounded between Lebesgue type spaces.In order t...In this paper,we investigate sufficient and necessary conditions such that generalized Forelli-Rudin type operators T_(λ,τ,k),S_(λ,τ,k),Q_(λ,τ,k)and R_(λ,τ,k)are bounded between Lebesgue type spaces.In order to prove the main results,we first give some bidirectional estimates for several typical integrals.展开更多
The hydraulic excitation acting on a hydro-turbine generator unit exhibits obvious non-stationary characteristics.In order to account for these characteristics,this study focuses on the non-stationary random vibration...The hydraulic excitation acting on a hydro-turbine generator unit exhibits obvious non-stationary characteristics.In order to account for these characteristics,this study focuses on the non-stationary random vibration reliability of the hydro-turbine generator unit.Firstly,the non-stationary characteristics of the hydraulic excitation are analyzed,and a mathematical ex-pression is constructed using the virtual excitation method.Secondly,a dynamic model of the unit is established to demonstrate the non-stationary random vibration characteristics under hydraulic excitation.Thirdly,an active learning non-stationary vibration reliability analysis method AK-MCS-T-H is proposed combining the Kriging model,the Monte Carlo simulation(MCS)method,and the information entropy learning function H.This method reveals the influence of the non-stationary hydraulic excitation on the random vibration reliability of the hydro-turbine generator unit.Finally,an example is presented to analyze the random vibration reliability.The study shows that the AK-MCS-T-H proposed in this paper can solve the problem of non-stationary random vibration reliability of the Francis hydro-turbine generator unit more effectively.展开更多
Artificial neural networks(ANN) have been extensively researched due to their significant energy-saving benefits.Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem. Th...Artificial neural networks(ANN) have been extensively researched due to their significant energy-saving benefits.Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem. This letter reports a dropout neuronal unit(1R1T-DNU) based on one memristor–one electrolyte-gated transistor with an ultralow energy consumption of 25 p J/spike. A dropout neural network is constructed based on such a device and has been verified by MNIST dataset, demonstrating high recognition accuracies(> 90%) within a large range of dropout probabilities up to40%. The running time can be reduced by increasing dropout probability without a significant loss in accuracy. Our results indicate the great potential of introducing such 1R1T-DNUs in full-hardware neural networks to enhance energy efficiency and to solve the overfitting problem.展开更多
Objective Intracranial hemorrhage(ICH),the second most common subtype of stroke,exacerbates the disruption of the blood-brain barrier(BBB),leading to vasogenic edema,plasma protein extravasation,and infiltration of ne...Objective Intracranial hemorrhage(ICH),the second most common subtype of stroke,exacerbates the disruption of the blood-brain barrier(BBB),leading to vasogenic edema,plasma protein extravasation,and infiltration of neurotoxic substances.The clearance capacity of the brain plays a crucial role in maintaining BBB homeostasis and facilitating patient recovery after hemorrhage.This study aimed to investigate the effect of circadian rhythms on BBB function,neuronal damage,and clearance capabilities.Methods The transwell model and hemoglobin were co-cultured to simulate the BBB environment after ICH.After intervention with different light groups,neuronal apoptosis was determined,glial phagocytosis was analyzed,the expression of endogenous clearing-related proteins aquaporin 4(AQP4)and low-density lipoprotein receptor-related protein 1(LRP1)was detected by western blotting and immunofluorescence dual standard method,and the expression of the tight junction protein occludin and melatonin receptor 1A(MTNR1A)was quantitatively analyzed.Results Circadian rhythms play a key role in maintaining the integrity of the BBB,reducing oxidative stress-induced neuronal damage,and improving microglial phagocytosis.Meanwhile,the expression of occludin and MTNR1A in neurovascular unit(NVU)co-cultured with hemoglobin improved the expression of AQP4 and LRP1,the key proteins in the NVU's endogenous brain clearance system.Conclusion Circadian rhythm(alternating black and white light)protects the NVU BBB function after ICH,promotes the expression of proteins related to the clearance of the hematoma,provides new evidence for the clinical treatment of patients recovering from ICH,and improves the circadian rhythm to promote brain metabolism and hematoma clearance.展开更多
First mirror(FM)cleaning,using radio frequency(RF)plasma,has been proposed to recover FM reflectivity in nuclear fusion reactors such as the International Thermonuclear Experimental Reactor(ITER).To investigate the in...First mirror(FM)cleaning,using radio frequency(RF)plasma,has been proposed to recover FM reflectivity in nuclear fusion reactors such as the International Thermonuclear Experimental Reactor(ITER).To investigate the influence of simultaneous cleaning of two mirrors on mirror cleaning efficiency and uniformity,experiments involving single-mirror cleaning and dual-mirror cleaning were conducted using RF capacitively coupled plasma in the laboratory.For the test and simultaneous cleaning of two mirrors,the FM and second mirror(SM),both measuring 110 mm×80 mm,were placed inside the first mirror unit(FMU).They were composed of 16 mirror samples,each with a dimension of 27.5 mm×20 mm.These mirror samples consist of a titanium-zirconium-molybdenum alloy substrate,a 500 nm Mo intermediate layer and a 30 nm Al_(2)O_(3) surface coating as a proxy for Be impurities.The cleaning of a single first mirror(SFM)and the simultaneous cleaning of the FM and SM(DFM and DSM)lasted for 9 h using Ar plasma at a pressure of 1 Pa.The total reflectivity of mirror samples on the DSM did not fully recover and varied with location,with a self-bias of−140 V.With a self-bias of−300 V,the total reflectivity of mirror samples on the SFM and DFM was fully recovered.The energy dispersive spectrometer results demonstrated that the Al_(2)O_(3) coating had been completely removed from these mirror samples.However,the mass loss of each mirror sample on the SFM and DFM before and after cleaning varied depending on its location,with higher mass loss observed for mirror samples located in the corners and lower loss for those in the center.Compared with SM cleaning,the simultaneous cleaning of two mirrors reduced the difference between the highest and lowest mass loss.Furthermore,this mass loss for the mirror samples of the DFM facing the DSM was increased.This indicated that mirror samples cleaned face to face in the FMU simultaneously could influence each other,highlighting the need for special attention in future studies.展开更多
This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details...This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details, and porosity.Therefore, a detailed analysis is required to investigate the exact state of their hydraulic interactions and structuralresponses. In this regard, the performance results of several traditional armour units, including the Antifer cube,Tetrapod, X-block and natural stone, are considered for the first step of this study. Then, the related observed resultsare compared with those obtained for a newly designed (artificial coral) armour unit. The research methodology utilizesthe common wave flume test procedure. Furthermore, several verified numerical models in OpenFOAM code areused to gain the extra required data. The proposed armour is configured to provide an effective shore protection as anenvironmental-friendly coastal structure. Thus it is designed with a main trunk including deep grooves to imitate thetypical geometry of a coral type configuration, so as to attain desirable performance. The observed results and ananalytic hierarchy process (AHP) concept are used to compare the hydraulic performance of the studied traditionaland newly proposed (artificial coral) armour units. The results indicate that the artificial coral armour unit demonstratesacceptable performance. The widely used traditional armour units might be replaced by newer designs for betterwave energy dissipation, and more importantly, for fewer adverse effects on the marine environment.展开更多
Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirm...Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirmed that the damage was caused by erosion-corrosion(E-C).Numerical and experimental methods were applied to investigate the E-C mechanism in the air cooler.Computational fluid dynamics(CFD)was used to calculate the hydrodynamic parameters of the air cooler.The results showed that there was a biased flow in the air cooler,which led to a significant increase in velocity,turbulent kinetic energy and wall shear within 0.2 m of the tube entrance.A visualization experiment was then performed to determine the principles of migration and transformation of multiphase flow in the air cooler tubes.Various flow patterns(pure droplet flow,mist flow,and annular flow)and their evolutionary processes were clearly depicted experimentally.The initiation mechanism and processes leading to the development of E-C in the air cooler were also determined.This study provided a comprehensive explanation for the E-C failures that occur in air coolers during operation.展开更多
The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thru...The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thrust belt(YFTB).However,there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period,specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean.The Nianzi granite unit exhibits unique petrological,geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB.This study presents detailed petrology,whole-rock geochemistry,together with Sr-Nd isotopic,zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit.Our findings demonstrate that the granites primarily consist of subhedral K-feldspar,plagioclase,quartz,minor biotite and hornblende,with accessory titanite,apatite,magnetite and zircon.Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5±0.62 Ma.Additionally,the adakitic characteristics of the Nianzi,Xiawopu and Xiaolianghou granitic intrusions,such as high Sr and Ba contents and high ratios of Sr/Y and(La/Yb)N,combined with negative Sr-Nd and Lu-Hf isotopes(87Sr/86Sr)i=0.705681–0.7057433,εNd(t)=−21.98 to−20.97,zirconεHf(t)=−20.26 to−9.92,as well as the I-type granite features of high SiO_(2),Na_(2)O and K_(2)O/Na_(2)O ratios,enriched Rb,K,Sr and Ba,along with depleted Th,U,Nb,Ta,P and Ti,suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous,calc-alkaline to high-K calc-alkaline,mafic to intermediate metamorphic rocks.In light of these parameters,we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic.展开更多
Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadr...Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.展开更多
Anthropogenic Nitrogen oxides(NO_(x)=NO_(2)+NO)emissions are highly concentrated in urban area,and the weekly cycles,seasonal patterns and long-term trends of tropospheric NO_(2)columns over cities differ from region ...Anthropogenic Nitrogen oxides(NO_(x)=NO_(2)+NO)emissions are highly concentrated in urban area,and the weekly cycles,seasonal patterns and long-term trends of tropospheric NO_(2)columns over cities differ from region to region due to different emission sectoral compositions and human activities.In this study,we used satellite observed tropospheric NO_(2)column data to compare the longand short-term NO_(2)column density time series over cities in the United Sates(the U.S.),western Europe and China.The results showed that in all the targeted cities,the outbreak of the Corona Virus Disease in 2019(COVID-19)moved the December peak of the city-level NO_(2)columns forward to November and October or even earlier in 2020 and 2021.On weekly level,cities in the U.S.show the lowest NO_(2)columns ratio on weekend/work day,then come the western European cities,and a weak weekly pattern is seen in Chinese cities.For all the cites,we find a higher weekend/work day NO_(2)ratio in cold seasons than in warm seasons,indicating a higher contribution from NOx emission sectors of residential,industry and power plants in the warm seasons.In the long-term,NO_(2)columns over the U.S.and western European cities declined by a fraction twice that of the regional mean level from 2004 to 2021.In China,NO_(2)columns started to decrease since 2012,at a similar rate between the city and regional level.This work confirms the importance to quantify and control NOx emissions from cities.展开更多
To equip data-driven dynamic chemical process models with strong interpretability,we develop a light attention–convolution–gate recurrent unit(LACG)architecture with three sub-modules—a basic module,a brand-new lig...To equip data-driven dynamic chemical process models with strong interpretability,we develop a light attention–convolution–gate recurrent unit(LACG)architecture with three sub-modules—a basic module,a brand-new light attention module,and a residue module—that are specially designed to learn the general dynamic behavior,transient disturbances,and other input factors of chemical processes,respectively.Combined with a hyperparameter optimization framework,Optuna,the effectiveness of the proposed LACG is tested by distributed control system data-driven modeling experiments on the discharge flowrate of an actual deethanization process.The LACG model provides significant advantages in prediction accuracy and model generalization compared with other models,including the feedforward neural network,convolution neural network,long short-term memory(LSTM),and attention-LSTM.Moreover,compared with the simulation results of a deethanization model built using Aspen Plus Dynamics V12.1,the LACG parameters are demonstrated to be interpretable,and more details on the variable interactions can be observed from the model parameters in comparison with the traditional interpretable model attention-LSTM.This contribution enriches interpretable machine learning knowledge and provides a reliable method with high accuracy for actual chemical process modeling,paving a route to intelligent manufacturing.展开更多
We present a systematic summary of the geological characteristics,exploration and development history and current state of shale oil and gas in the United States.The hydrocarbon-rich shales in the major shale basins o...We present a systematic summary of the geological characteristics,exploration and development history and current state of shale oil and gas in the United States.The hydrocarbon-rich shales in the major shale basins of the United States are mainly developed in six geological periods:Middle Ordovician,Middle-Late Devonian,Early Carboniferous(Middle-Late Mississippi),Early Permian,Late Jurassic,and Late Cretaceous(Cenomanian-Turonian).Depositional environments for these shales include intra-cratonic basins,foreland basins,and passive continental margins.Paleozoic hydrocarbon-rich shales are mainly developed in six basins,including the Appalachian Basin(Utica and Marcellus shales),Anadarko Basin(Woodford Shale),Williston Basin(Bakken Shale),Arkoma Basin(Fayetteville Shale),Fort Worth Basin(Barnett Shale),and the Wolfcamp and Leonardian Spraberry/Bone Springs shale plays of the Permian Basin.The Mesozoic hydrocarbon-rich shales are mainly developed on the margins of the Gulf of Mexico Basin(Haynesville and Eagle Ford)or in various Rocky Mountain basins(Niobrara Formation,mainly in the Denver and Powder River basins).The detailed analysis of shale plays reveals that the shales are different in facies and mineral components,and"shale reservoirs"are often not shale at all.The United States is abundant in shale oil and gas,with the in-place resources exceeding 0.246×10^(12)t and 290×10^(12)m^(3),respectively.Before the emergence of horizontal well hydraulic fracturing technology to kick off the"shale revolution",the United States had experienced two decades of exploration and production practices,as well as theory and technology development.In 2007-2023,shale oil and gas production in the United States increased from approximately 11.2×10^(4)tons of oil equivalent per day(toe/d)to over 300.0×10^(4)toe/d.In 2017,the shale oil and gas production exceeded the conventional oil and gas production in the country.In 2023,the contribution from shale plays to the total U.S.oil and gas production remained above 60%.The development of shale oil and gas has largely been driven by improvements in drilling and completion technologies,with much of the recent effort focused on“cube development”or“co-development”.Other efforts to improve productivity and efficiency include refracturing,enhanced oil recovery,and drilling of“U-shaped”wells.Given the significant resources base and continued technological improvements,shale oil and gas production will continue to contribute significant volumes to total U.S.hydrocarbon production.展开更多
基金the Natural Science Foundation of China(41807285)Interdisciplinary Innovation Fund of Natural Science,NanChang University(9167-28220007-YB2107).
文摘This study aims to investigate the effects of different mapping unit scales and study area scales on the uncertainty rules of landslide susceptibility prediction(LSP).To illustrate various study area scales,Ganzhou City in China,its eastern region(Ganzhou East),and Ruijin County in Ganzhou East were chosen.Different mapping unit scales are represented by grid units with spatial resolution of 30 and 60 m,as well as slope units that were extracted by multi-scale segmentation method.The 3855 landslide locations and 21 typical environmental factors in Ganzhou City are first determined to create spatial datasets with input-outputs.Then,landslide susceptibility maps(LSMs)of Ganzhou City,Ganzhou East and Ruijin County are pro-duced using a support vector machine(SVM)and random forest(RF),respectively.The LSMs of the above three regions are then extracted by mask from the LSM of Ganzhou City,along with the LSMs of Ruijin County from Ganzhou East.Additionally,LSMs of Ruijin at various mapping unit scales are generated in accordance.Accuracy and landslide suscepti-bility indexes(LSIs)distribution are used to express LSP uncertainties.The LSP uncertainties under grid units significantly decrease as study area scales decrease from Ganzhou City,Ganzhou East to Ruijin County,whereas those under slope units are less affected by study area scales.Of course,attentions should also be paid to the broader representativeness of large study areas.The LSP accuracy of slope units increases by about 6%–10%compared with those under grid units with 30 m and 60 m resolution in the same study area's scale.The significance of environmental factors exhibits an averaging trend as study area scale increases from small to large.The importance of environmental factors varies greatly with the 60 m grid unit,but it tends to be consistent to some extent in the 30 m grid unit and the slope unit.
文摘In this editorial,we comment on the article by Wang and Long,published in a recent issue of the World Journal of Clinical Cases.The article addresses the challenge of predicting intensive care unit-acquired weakness(ICUAW),a neuromuscular disorder affecting critically ill patients,by employing a novel processing strategy based on repeated machine learning.The editorial presents a dataset comprising clinical,demographic,and laboratory variables from intensive care unit(ICU)patients and employs a multilayer perceptron neural network model to predict ICUAW.The authors also performed a feature importance analysis to identify the most relevant risk factors for ICUAW.This editorial contributes to the growing body of literature on predictive modeling in critical care,offering insights into the potential of machine learning approaches to improve patient outcomes and guide clinical decision-making in the ICU setting.
文摘Intensive care unit-acquired weakness(ICU-AW)significantly hampers patient recovery and increases morbidity.With the absence of established preventive strategies,this study utilizes advanced machine learning methodologies to unearth key predictors of ICU-AW.Employing a sophisticated multilayer perceptron neural network,the research methodically assesses the predictive power for ICU-AW,pinpointing the length of ICU stay and duration of mechanical ventilation as pivotal risk factors.The findings advocate for minimizing these elements as a preventive approach,offering a novel perspective on combating ICU-AW.This research illuminates critical risk factors and lays the groundwork for future explorations into effective prevention and intervention strategies.
基金supported by the National Natural Science Foundation of China,Nos.81974207(to JH),82001383(to DW)the Special Clinical Research Project of Health Profession of Shanghai Municipal Health Commission,No.20204Y0076(to DW)。
文摘Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway.
文摘Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios.
基金supported by the NIH National Cancer Institute career development award(K25CA201545,to WL)。
文摘The neurovascular unit and stem cell therapy in ischemic stroke:Ischemic stroke,accounts for approximately 85% of all stroke incidents and is a major global health burden.It is the leading cause of disability and death worldwide,posing immense societal and economic challenges due to the long-term care required for stro ke survivors and the significant healthcare costs associated with its treatment and management(Amarenco et al.,2009).
基金The authors thank the Yayasan Universiti Teknologi PETRONAS(YUTP FRG Grant No.015LC0-428)at Universiti Teknologi PETRO-NAS for supporting this study.
文摘Static Poisson’s ratio(vs)is crucial for determining geomechanical properties in petroleum applications,namely sand production.Some models have been used to predict vs;however,the published models were limited to specific data ranges with an average absolute percentage relative error(AAPRE)of more than 10%.The published gated recurrent unit(GRU)models do not consider trend analysis to show physical behaviors.In this study,we aim to develop a GRU model using trend analysis and three inputs for predicting n s based on a broad range of data,n s(value of 0.1627-0.4492),bulk formation density(RHOB)(0.315-2.994 g/mL),compressional time(DTc)(44.43-186.9 μs/ft),and shear time(DTs)(72.9-341.2μ s/ft).The GRU model was evaluated using different approaches,including statistical error an-alyses.The GRU model showed the proper trends,and the model data ranges were wider than previous ones.The GRU model has the largest correlation coefficient(R)of 0.967 and the lowest AAPRE,average percent relative error(APRE),root mean square error(RMSE),and standard deviation(SD)of 3.228%,1.054%,4.389,and 0.013,respectively,compared to other models.The GRU model has a high accuracy for the different datasets:training,validation,testing,and the whole datasets with R and AAPRE values were 0.981 and 2.601%,0.966 and 3.274%,0.967 and 3.228%,and 0.977 and 2.861%,respectively.The group error analyses of all inputs show that the GRU model has less than 5% AAPRE for all input ranges,which is superior to other models that have different AAPRE values of more than 10% at various ranges of inputs.
基金supported by the Natural Science Foundation of Hunan Province of China(2022JJ30369)the Education Department Important Foundation of Hunan Province in China(23A0095)。
文摘In this paper,we investigate sufficient and necessary conditions such that generalized Forelli-Rudin type operators T_(λ,τ,k),S_(λ,τ,k),Q_(λ,τ,k)and R_(λ,τ,k)are bounded between Lebesgue type spaces.In order to prove the main results,we first give some bidirectional estimates for several typical integrals.
基金supported by the National Natural Science Foundation of China(Grant Nos.51465001 and 51905113)the Natural Science Foundation of Changsha City(Grant No.kq2208085)。
文摘The hydraulic excitation acting on a hydro-turbine generator unit exhibits obvious non-stationary characteristics.In order to account for these characteristics,this study focuses on the non-stationary random vibration reliability of the hydro-turbine generator unit.Firstly,the non-stationary characteristics of the hydraulic excitation are analyzed,and a mathematical ex-pression is constructed using the virtual excitation method.Secondly,a dynamic model of the unit is established to demonstrate the non-stationary random vibration characteristics under hydraulic excitation.Thirdly,an active learning non-stationary vibration reliability analysis method AK-MCS-T-H is proposed combining the Kriging model,the Monte Carlo simulation(MCS)method,and the information entropy learning function H.This method reveals the influence of the non-stationary hydraulic excitation on the random vibration reliability of the hydro-turbine generator unit.Finally,an example is presented to analyze the random vibration reliability.The study shows that the AK-MCS-T-H proposed in this paper can solve the problem of non-stationary random vibration reliability of the Francis hydro-turbine generator unit more effectively.
基金Project supported by the National Key Research and Development Program of China (Grant Nos. 2021YFA1202600 and 2023YFE0208600)in part by the National Natural Science Foundation of China (Grant Nos. 62174082, 92364106, 61921005, 92364204, and 62074075)。
文摘Artificial neural networks(ANN) have been extensively researched due to their significant energy-saving benefits.Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem. This letter reports a dropout neuronal unit(1R1T-DNU) based on one memristor–one electrolyte-gated transistor with an ultralow energy consumption of 25 p J/spike. A dropout neural network is constructed based on such a device and has been verified by MNIST dataset, demonstrating high recognition accuracies(> 90%) within a large range of dropout probabilities up to40%. The running time can be reduced by increasing dropout probability without a significant loss in accuracy. Our results indicate the great potential of introducing such 1R1T-DNUs in full-hardware neural networks to enhance energy efficiency and to solve the overfitting problem.
基金supported by the National Natural Science Foundation of China(No.82160237)the Key Research and Development Program in Hainan Province(No.ZDYF2023SHFZ104)Natural Science Foundation of Hainan Province(No.822MS210).
文摘Objective Intracranial hemorrhage(ICH),the second most common subtype of stroke,exacerbates the disruption of the blood-brain barrier(BBB),leading to vasogenic edema,plasma protein extravasation,and infiltration of neurotoxic substances.The clearance capacity of the brain plays a crucial role in maintaining BBB homeostasis and facilitating patient recovery after hemorrhage.This study aimed to investigate the effect of circadian rhythms on BBB function,neuronal damage,and clearance capabilities.Methods The transwell model and hemoglobin were co-cultured to simulate the BBB environment after ICH.After intervention with different light groups,neuronal apoptosis was determined,glial phagocytosis was analyzed,the expression of endogenous clearing-related proteins aquaporin 4(AQP4)and low-density lipoprotein receptor-related protein 1(LRP1)was detected by western blotting and immunofluorescence dual standard method,and the expression of the tight junction protein occludin and melatonin receptor 1A(MTNR1A)was quantitatively analyzed.Results Circadian rhythms play a key role in maintaining the integrity of the BBB,reducing oxidative stress-induced neuronal damage,and improving microglial phagocytosis.Meanwhile,the expression of occludin and MTNR1A in neurovascular unit(NVU)co-cultured with hemoglobin improved the expression of AQP4 and LRP1,the key proteins in the NVU's endogenous brain clearance system.Conclusion Circadian rhythm(alternating black and white light)protects the NVU BBB function after ICH,promotes the expression of proteins related to the clearance of the hematoma,provides new evidence for the clinical treatment of patients recovering from ICH,and improves the circadian rhythm to promote brain metabolism and hematoma clearance.
基金supported by the National Key R&D Project of China(No.2022YFE03030000)National Natural Science Foundation of China(Nos.11975269,12275306 and 12075279)+3 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2022452)the Anhui Provincial Natural Science Foundation(No.2208085J40)the CASHIPS Director’s Fund(Nos.YZJJQY202302 and BJPY2023B03)the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228).
文摘First mirror(FM)cleaning,using radio frequency(RF)plasma,has been proposed to recover FM reflectivity in nuclear fusion reactors such as the International Thermonuclear Experimental Reactor(ITER).To investigate the influence of simultaneous cleaning of two mirrors on mirror cleaning efficiency and uniformity,experiments involving single-mirror cleaning and dual-mirror cleaning were conducted using RF capacitively coupled plasma in the laboratory.For the test and simultaneous cleaning of two mirrors,the FM and second mirror(SM),both measuring 110 mm×80 mm,were placed inside the first mirror unit(FMU).They were composed of 16 mirror samples,each with a dimension of 27.5 mm×20 mm.These mirror samples consist of a titanium-zirconium-molybdenum alloy substrate,a 500 nm Mo intermediate layer and a 30 nm Al_(2)O_(3) surface coating as a proxy for Be impurities.The cleaning of a single first mirror(SFM)and the simultaneous cleaning of the FM and SM(DFM and DSM)lasted for 9 h using Ar plasma at a pressure of 1 Pa.The total reflectivity of mirror samples on the DSM did not fully recover and varied with location,with a self-bias of−140 V.With a self-bias of−300 V,the total reflectivity of mirror samples on the SFM and DFM was fully recovered.The energy dispersive spectrometer results demonstrated that the Al_(2)O_(3) coating had been completely removed from these mirror samples.However,the mass loss of each mirror sample on the SFM and DFM before and after cleaning varied depending on its location,with higher mass loss observed for mirror samples located in the corners and lower loss for those in the center.Compared with SM cleaning,the simultaneous cleaning of two mirrors reduced the difference between the highest and lowest mass loss.Furthermore,this mass loss for the mirror samples of the DFM facing the DSM was increased.This indicated that mirror samples cleaned face to face in the FMU simultaneously could influence each other,highlighting the need for special attention in future studies.
文摘This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details, and porosity.Therefore, a detailed analysis is required to investigate the exact state of their hydraulic interactions and structuralresponses. In this regard, the performance results of several traditional armour units, including the Antifer cube,Tetrapod, X-block and natural stone, are considered for the first step of this study. Then, the related observed resultsare compared with those obtained for a newly designed (artificial coral) armour unit. The research methodology utilizesthe common wave flume test procedure. Furthermore, several verified numerical models in OpenFOAM code areused to gain the extra required data. The proposed armour is configured to provide an effective shore protection as anenvironmental-friendly coastal structure. Thus it is designed with a main trunk including deep grooves to imitate thetypical geometry of a coral type configuration, so as to attain desirable performance. The observed results and ananalytic hierarchy process (AHP) concept are used to compare the hydraulic performance of the studied traditionaland newly proposed (artificial coral) armour units. The results indicate that the artificial coral armour unit demonstratesacceptable performance. The widely used traditional armour units might be replaced by newer designs for betterwave energy dissipation, and more importantly, for fewer adverse effects on the marine environment.
基金supported by the National Key R&D Program of China(2021YFB3301100)Beijing University of Chemical Technology Interdisciplinary Program(XK2023-07).
文摘Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirmed that the damage was caused by erosion-corrosion(E-C).Numerical and experimental methods were applied to investigate the E-C mechanism in the air cooler.Computational fluid dynamics(CFD)was used to calculate the hydrodynamic parameters of the air cooler.The results showed that there was a biased flow in the air cooler,which led to a significant increase in velocity,turbulent kinetic energy and wall shear within 0.2 m of the tube entrance.A visualization experiment was then performed to determine the principles of migration and transformation of multiphase flow in the air cooler tubes.Various flow patterns(pure droplet flow,mist flow,and annular flow)and their evolutionary processes were clearly depicted experimentally.The initiation mechanism and processes leading to the development of E-C in the air cooler were also determined.This study provided a comprehensive explanation for the E-C failures that occur in air coolers during operation.
基金funded by the National Natural Science Foundation of China(41872232)the Beijing Geological Survey Project(PXM 2016-158203-000008,PXM 2018-158203-000014)the Beijing Innovation Studio(Urban Geology,Active Structure,and Monitoring).
文摘The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thrust belt(YFTB).However,there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period,specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean.The Nianzi granite unit exhibits unique petrological,geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB.This study presents detailed petrology,whole-rock geochemistry,together with Sr-Nd isotopic,zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit.Our findings demonstrate that the granites primarily consist of subhedral K-feldspar,plagioclase,quartz,minor biotite and hornblende,with accessory titanite,apatite,magnetite and zircon.Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5±0.62 Ma.Additionally,the adakitic characteristics of the Nianzi,Xiawopu and Xiaolianghou granitic intrusions,such as high Sr and Ba contents and high ratios of Sr/Y and(La/Yb)N,combined with negative Sr-Nd and Lu-Hf isotopes(87Sr/86Sr)i=0.705681–0.7057433,εNd(t)=−21.98 to−20.97,zirconεHf(t)=−20.26 to−9.92,as well as the I-type granite features of high SiO_(2),Na_(2)O and K_(2)O/Na_(2)O ratios,enriched Rb,K,Sr and Ba,along with depleted Th,U,Nb,Ta,P and Ti,suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous,calc-alkaline to high-K calc-alkaline,mafic to intermediate metamorphic rocks.In light of these parameters,we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic.
基金The work is supported by the National Natural Science Foundation of China(Nos.U21A20124 and 52205059)the Key Research and Development Program of Zhejiang Province(No.2022C01039)。
文摘Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.
基金Under the auspices of the National Natural Science Foundation of China(No.42375106,41805098)the National Key R&D Program of China(No.2023YFB3907500)。
文摘Anthropogenic Nitrogen oxides(NO_(x)=NO_(2)+NO)emissions are highly concentrated in urban area,and the weekly cycles,seasonal patterns and long-term trends of tropospheric NO_(2)columns over cities differ from region to region due to different emission sectoral compositions and human activities.In this study,we used satellite observed tropospheric NO_(2)column data to compare the longand short-term NO_(2)column density time series over cities in the United Sates(the U.S.),western Europe and China.The results showed that in all the targeted cities,the outbreak of the Corona Virus Disease in 2019(COVID-19)moved the December peak of the city-level NO_(2)columns forward to November and October or even earlier in 2020 and 2021.On weekly level,cities in the U.S.show the lowest NO_(2)columns ratio on weekend/work day,then come the western European cities,and a weak weekly pattern is seen in Chinese cities.For all the cites,we find a higher weekend/work day NO_(2)ratio in cold seasons than in warm seasons,indicating a higher contribution from NOx emission sectors of residential,industry and power plants in the warm seasons.In the long-term,NO_(2)columns over the U.S.and western European cities declined by a fraction twice that of the regional mean level from 2004 to 2021.In China,NO_(2)columns started to decrease since 2012,at a similar rate between the city and regional level.This work confirms the importance to quantify and control NOx emissions from cities.
基金support provided by the National Natural Science Foundation of China(22122802,22278044,and 21878028)the Chongqing Science Fund for Distinguished Young Scholars(CSTB2022NSCQ-JQX0021)the Fundamental Research Funds for the Central Universities(2022CDJXY-003).
文摘To equip data-driven dynamic chemical process models with strong interpretability,we develop a light attention–convolution–gate recurrent unit(LACG)architecture with three sub-modules—a basic module,a brand-new light attention module,and a residue module—that are specially designed to learn the general dynamic behavior,transient disturbances,and other input factors of chemical processes,respectively.Combined with a hyperparameter optimization framework,Optuna,the effectiveness of the proposed LACG is tested by distributed control system data-driven modeling experiments on the discharge flowrate of an actual deethanization process.The LACG model provides significant advantages in prediction accuracy and model generalization compared with other models,including the feedforward neural network,convolution neural network,long short-term memory(LSTM),and attention-LSTM.Moreover,compared with the simulation results of a deethanization model built using Aspen Plus Dynamics V12.1,the LACG parameters are demonstrated to be interpretable,and more details on the variable interactions can be observed from the model parameters in comparison with the traditional interpretable model attention-LSTM.This contribution enriches interpretable machine learning knowledge and provides a reliable method with high accuracy for actual chemical process modeling,paving a route to intelligent manufacturing.
基金supported by the State of Texas Advanced Resource Recovery(STARR)programthe Bureau of Economic Geology's Tight Oil Resource Assessment(TORA)Mudrock Systems Research Laboratory(MSRL)consortia。
文摘We present a systematic summary of the geological characteristics,exploration and development history and current state of shale oil and gas in the United States.The hydrocarbon-rich shales in the major shale basins of the United States are mainly developed in six geological periods:Middle Ordovician,Middle-Late Devonian,Early Carboniferous(Middle-Late Mississippi),Early Permian,Late Jurassic,and Late Cretaceous(Cenomanian-Turonian).Depositional environments for these shales include intra-cratonic basins,foreland basins,and passive continental margins.Paleozoic hydrocarbon-rich shales are mainly developed in six basins,including the Appalachian Basin(Utica and Marcellus shales),Anadarko Basin(Woodford Shale),Williston Basin(Bakken Shale),Arkoma Basin(Fayetteville Shale),Fort Worth Basin(Barnett Shale),and the Wolfcamp and Leonardian Spraberry/Bone Springs shale plays of the Permian Basin.The Mesozoic hydrocarbon-rich shales are mainly developed on the margins of the Gulf of Mexico Basin(Haynesville and Eagle Ford)or in various Rocky Mountain basins(Niobrara Formation,mainly in the Denver and Powder River basins).The detailed analysis of shale plays reveals that the shales are different in facies and mineral components,and"shale reservoirs"are often not shale at all.The United States is abundant in shale oil and gas,with the in-place resources exceeding 0.246×10^(12)t and 290×10^(12)m^(3),respectively.Before the emergence of horizontal well hydraulic fracturing technology to kick off the"shale revolution",the United States had experienced two decades of exploration and production practices,as well as theory and technology development.In 2007-2023,shale oil and gas production in the United States increased from approximately 11.2×10^(4)tons of oil equivalent per day(toe/d)to over 300.0×10^(4)toe/d.In 2017,the shale oil and gas production exceeded the conventional oil and gas production in the country.In 2023,the contribution from shale plays to the total U.S.oil and gas production remained above 60%.The development of shale oil and gas has largely been driven by improvements in drilling and completion technologies,with much of the recent effort focused on“cube development”or“co-development”.Other efforts to improve productivity and efficiency include refracturing,enhanced oil recovery,and drilling of“U-shaped”wells.Given the significant resources base and continued technological improvements,shale oil and gas production will continue to contribute significant volumes to total U.S.hydrocarbon production.
