The processes of flooding—water flooding, polymer flooding and ternary combination flooding—were simulated respectively on a 2-D positive rhythm profile geological model by using the ASP numerical modeling softw...The processes of flooding—water flooding, polymer flooding and ternary combination flooding—were simulated respectively on a 2-D positive rhythm profile geological model by using the ASP numerical modeling software developed by RIPED (Yuan, et al. 1995). The recovery coefficient, remaining oil saturation, sweep efficiency and displacement efficiency were calculated and correlated layer by layer. The results show that the sweep efficiency and displacement efficiency work different effects on different layers in the severely heterogeneous reservoir. The study shows that the displacement efficiency and sweep efficiency play different roles in different layers for severely heterogeneous reservoirs. The displacement efficiency contributes mainly to the high permeability zones, the sweep efficiency to the low permeability zones, both of which contribute to the middle permeable zones. To improve the sweep efficiency in the low permeability zones is of significance for enhancing the whole recovery of the reservoir. It is an important path for improving the effectiveness of chemical flooding in the severely heterogeneous reservoirs to inject ternary combination slug after profile control.展开更多
Enhancing the efficiency of Rankine cycles is crucial for improving the performance of thermal power plants,as it directly impacts operational costs and emissions in light of energy transition goals.This study sets it...Enhancing the efficiency of Rankine cycles is crucial for improving the performance of thermal power plants,as it directly impacts operational costs and emissions in light of energy transition goals.This study sets itself apart from existing research by applying a novel optimization technique to a basic ideal Rankine cycle,focusing on a specific power plant that has not been previously analyzed.Currently,this cycle operates at 41%efficiency and a steam quality of 76%,constrained by fixed operational parameters.The primary objectives are to increase thermal efficiency beyond 46%and raise steam quality above 85%,while adhering to operational limits:a boiler pressure not exceeding 15 MPa,condenser pressure not dropping below 10 kPa,and turbine temperature not surpassing 500℃.This study utilizes numerical simulations to model the effects of varying boiler pressure(Pb)and condenser pressure(Pc)within the ranges of 12MPa<Pb<15 MPa and 5 kPa<Pc<10 kPa.By systematically adjusting these parameters,the proposed aimto identify optimal conditions that maximize efficiency and performance within specified constraints.The findings will provide valuable insights for power plant operators seeking to optimize performance under real-world conditions,contributing to more efficient and sustainable power generation.展开更多
With the objective of investigating the basis of phosphorus(P)utilization efficiency(PUE),physiological and morphological traits,two P-efficient and two P-inefficient rapeseed(Brassica napus L.)cultivars were compared...With the objective of investigating the basis of phosphorus(P)utilization efficiency(PUE),physiological and morphological traits,two P-efficient and two P-inefficient rapeseed(Brassica napus L.)cultivars were compared at the seedling stage.P-efficient cultivars showed root morphological adaptation,high P uptake activity,and greater phospholipid degradation under low P stress.Improving root morphological adaptation and reducing lipid-P allocation could allow increasing PUE in rapeseed seedlings.展开更多
BACKGROUND In 2017,our institution implemented a high efficiency(HE)pathway for lower limb orthopedic surgery.The employed strategy included patient selection,surgical instrument standardization,preoperative surgical ...BACKGROUND In 2017,our institution implemented a high efficiency(HE)pathway for lower limb orthopedic surgery.The employed strategy included patient selection,surgical instrument standardization,preoperative surgical nerve blocks,avoidance of general anesthesia and bypassing phase one recovery.We conducted a historic cohort study whose primary outcome was the postoperative recovery time between the HE and traditional(T)pathway.AIM To determine whether the implementation of a HE pathway was correlated with a reduction in postoperative recovery time.METHODS Patients who had unilateral elective lower limb orthopedic procedures through the T and HE pathway were screened between 2017 to 2019.Patients were at least 18 years old,and American Society of Anesthesiologists(ASA)Physical Status I to III without major systemic comorbidities were included.Propensity score was generated using multivariable regression taking age,body mass index,sex,ASA class and surgical type as covariates using nearest neighbour methods between the two pathways.Mann Whitney U test were used to analyzed total postoperative time.RESULTS There was an associated reduction in total postoperative recovery time of 63 minutes(95%CI:-69 to-57)in the HE group.The operating room time and total length of stay also had an associated decrease of 20 minutes(95%CI:-23 to-17)and 84 minutes(95%CI:-92 to-75)respectively.CONCLUSION Utilizing multifaceted strategies to improve perioperative efficiency was associated with a reduction in the postoperative recovery time in our retrospective study.This model can be a potential strategy to deal with surgical backlog in the face of ongoing human resource challenges.展开更多
This study takes the panel data of 278 prefecture-level cities in China from 2011 to 2022 as samples,constructs a super-efficiency SBM model to measure urban energy-environment efficiency,uses the entropy method to sy...This study takes the panel data of 278 prefecture-level cities in China from 2011 to 2022 as samples,constructs a super-efficiency SBM model to measure urban energy-environment efficiency,uses the entropy method to synthesize the digital economy composite index,and introduces the green innovation index as a mediating variable.Breaking through the traditional analysis framework in the empirical method:Firstly,through the fixed-effects model and mediating-effect test,it reveals the direct impact of the digital economy on energy-environment efficiency and the transmission path of green innovation.Secondly,it divides the eastern,central,and western regions and low-carbon pilot cities for heterogeneity tests to identify the moderating effect of policy intervention.Thirdly,it strengthens the robustness of the conclusions by replacing the super-efficiency CCR model,shortening the sample period,and performing winsorization.The study finds that the digital economy significantly improves energy-environment efficiency through green technology innovation.These conclusions provide an empirical basis for optimizing the layout of digital infrastructure and improving the regional collaborative emission-reduction mechanism.展开更多
The growing need for sustainable energy solutions,driven by rising energy shortages,environmental concerns,and the depletion of conventional energy sources,has led to a significant focus on renewable energy.Solar ener...The growing need for sustainable energy solutions,driven by rising energy shortages,environmental concerns,and the depletion of conventional energy sources,has led to a significant focus on renewable energy.Solar energy,among the various renewable sources,is particularly appealing due to its abundant availability.However,the efficiency of commercial solar photovoltaic(PV)modules is hindered by several factors,notably their conversion efficiency,which averages around 19%.This efficiency can further decline to 10%–16%due to temperature increases during peak sunlight hours.This study investigates the cooling of PV modules by applying water to their front surface through Computational fluid dynamics(CFD).The study aimed to determine the optimal conditions for cooling the PV module by analyzing the interplay between water film thickness,Reynolds number,and their effects on temperature reduction and heat transfer.The CFD analysis revealed that the most effective cooling condition occurred with a 5 mm thick water film and a Reynolds number of 10.These specific parameters were found to maximize the heat transfer and temperature reduction efficiency.This finding is crucial for the development of practical and efficient cooling systems for PV modules,potentially leading to improved performance and longevity of solar panels.Alternative cooling fluids or advanced cooling techniques that might offer even better efficiency or practical benefits.展开更多
The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to...The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to the TiO 2/UV photocatalysis system. Furthermore, for the immobility system (IS), the formulation of the faction of light absorbed by the TiO 2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity (T). For the suspension system(SS), due to the difficulty to obtain the absorption coefficient ( α ) of TiO 2 particulates, the quantum efficiency is calculated by means of the relative photonic efficiency ( ζ r) and the standard quantum yield ( Φ standard ).展开更多
The study measures productive efficiency of tomato growers in village Akbarpura of Disctrict Nowshera in Khyber Pakhtunkhwa （KPK） province of Northern Pakistan. The study uses household level data collected in summe...The study measures productive efficiency of tomato growers in village Akbarpura of Disctrict Nowshera in Khyber Pakhtunkhwa （KPK） province of Northern Pakistan. The study uses household level data collected in summer 2010 from sample farmers selected by multi-staged sampling. The study uses a theoretical framework to measure productive efficiency and estimates the Cobb-Douglas frontier production and cost models. The study found that technical efficiency indices varied significantly, with technical efficiency index averaging at 65%. The indices of allocative efficiency also varied widely, with an average of 56%. There was a wide gap between the highest and lowest economic efficiency indices, with a mean economic efficiency of 35%. The study concluded that farmer education, extension visits, age and access to credit contributed significantly and positively to productive efficiencies. A policy implication of this study is that there is enough potential for farmers to increase tomato production and net profits. The study recommends that the government should further invest in public education and strengthen extension services farmer education and because extension visits constituted important determinants of productive efficiencies.展开更多
Water use efficiency(WUE),as a pivotal indicator of the coupling degree within the carbon–water cycle of ecosystems,holds considerable importance in assessment of the carbon–water balance within terrestrial ecosyste...Water use efficiency(WUE),as a pivotal indicator of the coupling degree within the carbon–water cycle of ecosystems,holds considerable importance in assessment of the carbon–water balance within terrestrial ecosystems.However,in the context of global warming,WUE evolution and its primary drivers on the Tibetan Plateau remain unclear.This study employed the ensemble empirical mode decomposition method and the random forest algorithm to decipher the nonlinear trends and drivers of WUE on the Tibetan Plateau in 2001–2020.Results indicated an annual mean WUE of 0.8088 gC/mm·m^(2)across the plateau,with a spatial gradient reflecting decrease from the southeast toward the northwest.Areas manifesting monotonous trends of increase or decrease in WUE accounted for 23.64%and 9.69%of the total,respectively.Remarkably,66.67%of the region exhibited trend reversals,i.e.,39.94%of the area of the Tibetan Plateau showed transition from a trend of increase to a trend of decrease,and 26.73%of the area demonstrated a shift from a trend of decrease to a trend of increase.Environmental factors accounted for 70.79%of the variability in WUE.The leaf area index and temperature served as the major driving forces of WUE variation.展开更多
The increase in soil temperature associated with climate change has introduced considerable challenges to crop production.Split nitrogen application(SN)represents a potential strategy for improving crop nitrogen use e...The increase in soil temperature associated with climate change has introduced considerable challenges to crop production.Split nitrogen application(SN)represents a potential strategy for improving crop nitrogen use efficiency and enhancing crop stress resistance.Nevertheless,the precise interaction between soil warming(SW)and SN remains unclear.In order to ascertain the impact of SW on maize growth and whether SN can improve the tolerance of maize to SW,a two-year field experiment was conducted(2022-2023).The aim was to examine the influence of two SW ranges(MT,warming 1.40℃;HT,warming 2.75℃)and two nitrogen application methods(N1,one-time basal application of nitrogen fertilizer;N2,one third of base nitrogen fertilizer+two thirds of jointing stage supplemental nitrogen fertilizer)on maize root growth,photosynthetic characteristics,nitrogen use efficiency,and yield.The results demonstrated that SW impeded root growth and precipitated the premature aging of maize leaves following anthesis,particularly in the HT,which led to a notable reduction in maize yield.In comparison to N1,SN has been shown to increase root length density by 8.54%,root bleeding rate by 8.57%,and enhance root distribution ratio in the middle soil layers(20-60 cm).The interaction between SW and SN had a notable impact on maize growth and yield.The SN improved the absorption and utilization efficiency of nitrogen by promoting root development and downward canopy growth,thus improving the tolerance of maize to SW at the later stage of growth.In particular,the N2HT resulted in a 14.51%increase in the photosynthetic rate,a 18.58%increase in nitrogen absorption efficiency,and a 18.32%increase in maize yield compared with N1HT.It can be posited that the SN represents a viable nitrogen management measure with the potential to enhance maize tolerance to soil high-temperature stress.展开更多
The mechanism of hydrate-based desalination is that water molecules would transfer to the hydrate phase during gas hydrate formation process,while the salt ions would be conversely concentrated in the unreacted saltwa...The mechanism of hydrate-based desalination is that water molecules would transfer to the hydrate phase during gas hydrate formation process,while the salt ions would be conversely concentrated in the unreacted saltwater.However,the salt concentration of hydrate decomposed water and the desalination degree of hydrate phase are still unclear.The biggest challenge is how to effectively separate the hydrate phase and the remaining unreacted salt water,and then decompose the hydrate phase to measure the salt concentration of hydrate melt water.This work developed an apparatus and pressure-driven filtration method to efficiently separate the hydrate phase and the remaining unreacted saltwater.On this basis,the single hydrate phase was obtained,then it was dissociated and the salt concentration of hydrate melt water was measured.The experimental results demonstrate that when the initial salt mass concentration is 0.3% to 8.0%,the salt removal efficiency for NaCl solution is 15.9% to 29.8%by forming CO_(2) hydrate,while for CaCl_(2) solution is 28.9%to 45.5%.The solute CaCl_(2) is easier to be removed than solute NaCl.In addition,the salt removal efficiency for forming CO_(2) hydrate is higher than that for forming methane hydrate.The multi-stage desalination can continuously decrease the salt concentration of hydrate dissociated water,and the salt removal efficiency per stage is around 20%.展开更多
The effects of micro-ridge-furrow planting(MR)on yield and the efficiency of light,water,and thermal resource use in rapeseed were tested in a three-year field experiment comparing MR to conventional flat planting.MR ...The effects of micro-ridge-furrow planting(MR)on yield and the efficiency of light,water,and thermal resource use in rapeseed were tested in a three-year field experiment comparing MR to conventional flat planting.MR enhanced canopy heterogeneity by altering the leaf angle between plants on ridges and furrows.The heterogeneous canopy environment increased intercepted photosynthetic active radiation,alleviated canopy temperature stress,and optimized canopy humidity,leading to improvements in light-nitrogen matching and net photosynthetic rate.Consequently,dry matter and yield increased by 13.0%and 11.0%,respectively,while radiation,thermal,and precipitation utilization efficiency increased by 12.3%-16.2%.The corresponding improvements in yield and resource use efficiency were attributed to a heterogeneous canopy environment that improved microclimatic conditions.展开更多
To make agricultural systems sustainable in terms of their greenness and efficiency,optimizing the tillage and fertilization practices is essential.To assess the effects of tilling and fertilization practices in wheat...To make agricultural systems sustainable in terms of their greenness and efficiency,optimizing the tillage and fertilization practices is essential.To assess the effects of tilling and fertilization practices in wheat-maize cropping systems,a three-year field experiment was designed to quantify the carbon footprint(CF)and energy efficiency of the cropping systems in the North China Plain.The study parameters included four tillage practices(no tillage(NT),conventional tillage(CT),rotary tillage(RT),and subsoiling rotary tillage(SRT))and two fertilizer regimes(inorganic fertilizer(IF)and hybrid fertilizer with organic and inorganic components(HF)).The results indicated that the most prominent energy inputs and greenhouse gas(GHG)emissions could be ascribed to the use of fertilizers and fuel consumption.Under the same fertilization regime,ranking the tillage patterns with respect to the value of the crop yield,profit,CF,energy use efficiency(EUE)or energy productivity(EP)for either wheat or maize always gave the same sequence of SRT>RT>CT>NT.For the same tillage,the energy consumption associated with HF was higher than IF,but its GHG emissions and CF were lower while the yield and profit were higher.In terms of overall performance,tilling is more beneficial than NT,and reduced tillage practices(RT and SRT)are more beneficial than CT.The fertilization regime with the best overall performance was HF.Combining SRT with HF has significant potential for reducing CF and increasing EUE,thereby improving sustainability.Adopting measures that promote these optimizations can help to overcome the challenges posed by a lack of food security,energy crises and ecological stress.展开更多
Trochoidal milling is known for its advantages in machining difficult-to-machine materials as it facilitates chip removal and tool cooling.However,the conventional trochoidal tool path presents challenges such as lowe...Trochoidal milling is known for its advantages in machining difficult-to-machine materials as it facilitates chip removal and tool cooling.However,the conventional trochoidal tool path presents challenges such as lower machining efficiency and longer machining time due to its time-varying cutter-workpiece engagement angle and a high percentage of non-cutting tool paths.To address these issues,this paper introduces a parameter-variant trochoidal-like(PVTR)tool path planning method for chatter-free and high-efficiency milling.This method ensures a constant engagement angle for each tool path period by adjusting the trochoidal radius and step.Initially,the nonlinear equation for the PVTR toolpath is established.Then,a segmented recurrence method is proposed to plan tool paths based on the desired engagement angle.The impact of trochoidal tool path parameters on the engagement angle is analyzed and coupled this information with the milling stability model based on spindle speed and engagement angle to determine the desired engagement angle throughout the machining process.Finally,several experimental tests are carried out using the bull-nose end mill to validate the feasibility and effectiveness of the proposed method.展开更多
Although phase-change random-access memory(PCRAM)is a promising next-generation nonvolatile memory technology,challenges remain in terms of reducing energy consumption.This is primarily be-cause the high thermal condu...Although phase-change random-access memory(PCRAM)is a promising next-generation nonvolatile memory technology,challenges remain in terms of reducing energy consumption.This is primarily be-cause the high thermal conductivities of phase-change materials(PCMs)promote Joule heating dissi-pation.Repeated phase transitions also induce long-range atomic diffusion,limiting the durability.To address these challenges,phase-change heterostructure(PCH)devices that incorporate confinement sub-layers based on transition-metal dichalcogenide materials have been developed.In this study,we engi-neered a PCH device by integrating HfTe_(2),which has low thermal conductivity and excellent stability,into the PCM to realize PCRAM with enhanced thermal efficiency and structural stability.HEAT sim-ulations were conducted to validate the superior heat confinement in the programming region of the HfTe_(2)-based PCH device.Moreover,electrical measurements of the device demonstrated its outstanding performance,which was characterized by a low RESET current(∼1.6 mA),stable two-order ON/OFF ratio,and exceptional cycling endurance(∼2×10^(7)).The structural integrity of the HfTe_(2)confinement sub-layer was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy.The material properties,including electrical conductivity,cohesive energy,and electronegativity,substantiated these findings.Collectively,these results revealed that the HfTe_(2)-based PCH device can achieve significant improvements in performance and reliability compared with conventional PCRAM devices.展开更多
Ultra-low emission of nitrogen oxide(NO_(x))is an irreversible trend for the development of waste-to-energy industry.But traditional approaches to remove NO_(x) face significant challenge s,such as low denitration eff...Ultra-low emission of nitrogen oxide(NO_(x))is an irreversible trend for the development of waste-to-energy industry.But traditional approaches to remove NO_(x) face significant challenge s,such as low denitration efficiency,complex denitration system,and high investment and operating cost.Here we put forward a novel polymer non-catalytic reduction(PNCR)technology that utilized a new type of polymer agent to remove NO_(x),and the proposed PNCR technology was applied to the existing waste-to-energy plant to test the denitration performance.The PNCR technology demonstrated excellent denitration performance with a NO_(x) emission concentration of<100 mg/Nm^(3) and high denitration efficiency of>75%at the temperature range of 800-900℃,which showed the application feasibility even on the complex and unstable industrial operating conditions.In addition,PNCR and hybrid polymer/selective non-catalytic reduction(PNCR/SNCR)technology possessed remarkable economic advantages including low investment fee and low operating cost of<10 CNY per ton of municipal solid waste(MSW)compared with selective catalytic reduction(SCR)technology.The excellent denitration performance of PNCR technology forebodes a broad industrial application prospect in the field of flue gas cleaning for waste-to-energy plants.展开更多
Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.Howe...Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.展开更多
This work focuses on maximizing the minimum user’s security energy efficiency(SEE)in an unmanned aerial vehicle-mounted reconfigurable intelligent surface(UAV-RIS)enhanced short-packet communication(SPC)system.The ba...This work focuses on maximizing the minimum user’s security energy efficiency(SEE)in an unmanned aerial vehicle-mounted reconfigurable intelligent surface(UAV-RIS)enhanced short-packet communication(SPC)system.The base station(BS)provides short packet services to ground users using the non-orthogonal multiple access(NOMA)protocol through UAV-RIS,while preventing eavesdropper attacks.To optimize SEE,a joint optimization is performed concerning power allocation,UAV position,decoding order,and RIS phase shifts.An iterative algorithm based on block coordinate descent is proposed for mixed-integer non-convex SEE optimization problem.The original problem is decomposed into three sub-problems,solved alternately using successive convex approximation(SCA),quadratic transformation,penalty function,and semi-definite programming(SDP).Simulation results demonstrate the performance of the UAV-RIS-enhanced short-packet system under different parameters and verify the algorithm’s convergence.Compared to benchmark schemes such as orthogonal multiple access,long packet communication,and sum SEE,the proposed UAV-RIS-enhanced short-packet scheme achieves the higher minimum user’s SEE.展开更多
Trap-assisted charge recombination is one of the primary limitationsof restricting the performance of organic solar cells. However, effectivelyreducing the presence of traps in the photoactive layer remains challengin...Trap-assisted charge recombination is one of the primary limitationsof restricting the performance of organic solar cells. However, effectivelyreducing the presence of traps in the photoactive layer remains challenging.Herein, wide bandgap polymer donor PTzBI-dF is demonstrated as an effectivemodulator for enhancing the crystallinity of the bulk heterojunction active layerscomposed of D18 derivatives blended with Y6, leading to dense and orderedmolecular packings, and thus, improves photoluminescence quenching properties.As a result, the photovoltaic devices exhibit reduced trap-assisted charge recombinationlosses, achieving an optimized power conversion efficiency of over 19%.Besides the efficiency enhancement, the devices comprised of PTzBI-dF as athird component simultaneously attain decreased current leakage, improved chargecarrier mobilities, and suppressed bimolecular charge recombination, leading toreduced energy losses. The advanced crystalline structures induced by PTzBI-dFand its characteristics, such as well-aligned energy level, and complementaryabsorption spectra, are ascribed to the promising performance improvements.Our findings suggest that donor phase engineering is a feasible approach to tuning the molecular packings in the active layer, providingguidelines for designing effective morphology modulators for high-performance organic solar cells.展开更多
In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads th...In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide.This is equivalent to including an additional inductance-capacitance for energy storage,which realizes the slow-wave effect.A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth.In the frequency band between 8-12 GHz,the measured results show that the delay multiplier of the delay line reaches 4 times,i.e.,delay line’s delay time is 4 times larger than 50Ωmicrostrip line with same length.Furthermore,the delay fluctuation,i.e.,the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%,the insertion loss is less than-2.5 dB,and the return loss is less than-15 dB.Compared with the existing delay lines,the proposed delay line has the advantages of high delay efficiency,low delay error,wide bandwidth and low loss,which has good practical value and application prospects.展开更多
基金This project is supported by the China National Key Basis Research Project (No: G1999022512)
文摘The processes of flooding—water flooding, polymer flooding and ternary combination flooding—were simulated respectively on a 2-D positive rhythm profile geological model by using the ASP numerical modeling software developed by RIPED (Yuan, et al. 1995). The recovery coefficient, remaining oil saturation, sweep efficiency and displacement efficiency were calculated and correlated layer by layer. The results show that the sweep efficiency and displacement efficiency work different effects on different layers in the severely heterogeneous reservoir. The study shows that the displacement efficiency and sweep efficiency play different roles in different layers for severely heterogeneous reservoirs. The displacement efficiency contributes mainly to the high permeability zones, the sweep efficiency to the low permeability zones, both of which contribute to the middle permeable zones. To improve the sweep efficiency in the low permeability zones is of significance for enhancing the whole recovery of the reservoir. It is an important path for improving the effectiveness of chemical flooding in the severely heterogeneous reservoirs to inject ternary combination slug after profile control.
文摘Enhancing the efficiency of Rankine cycles is crucial for improving the performance of thermal power plants,as it directly impacts operational costs and emissions in light of energy transition goals.This study sets itself apart from existing research by applying a novel optimization technique to a basic ideal Rankine cycle,focusing on a specific power plant that has not been previously analyzed.Currently,this cycle operates at 41%efficiency and a steam quality of 76%,constrained by fixed operational parameters.The primary objectives are to increase thermal efficiency beyond 46%and raise steam quality above 85%,while adhering to operational limits:a boiler pressure not exceeding 15 MPa,condenser pressure not dropping below 10 kPa,and turbine temperature not surpassing 500℃.This study utilizes numerical simulations to model the effects of varying boiler pressure(Pb)and condenser pressure(Pc)within the ranges of 12MPa<Pb<15 MPa and 5 kPa<Pc<10 kPa.By systematically adjusting these parameters,the proposed aimto identify optimal conditions that maximize efficiency and performance within specified constraints.The findings will provide valuable insights for power plant operators seeking to optimize performance under real-world conditions,contributing to more efficient and sustainable power generation.
基金supported by the National Key Research and Development Program of China(2024YFD2301200)National Nature Science Foundation of China(32172662).
文摘With the objective of investigating the basis of phosphorus(P)utilization efficiency(PUE),physiological and morphological traits,two P-efficient and two P-inefficient rapeseed(Brassica napus L.)cultivars were compared at the seedling stage.P-efficient cultivars showed root morphological adaptation,high P uptake activity,and greater phospholipid degradation under low P stress.Improving root morphological adaptation and reducing lipid-P allocation could allow increasing PUE in rapeseed seedlings.
文摘BACKGROUND In 2017,our institution implemented a high efficiency(HE)pathway for lower limb orthopedic surgery.The employed strategy included patient selection,surgical instrument standardization,preoperative surgical nerve blocks,avoidance of general anesthesia and bypassing phase one recovery.We conducted a historic cohort study whose primary outcome was the postoperative recovery time between the HE and traditional(T)pathway.AIM To determine whether the implementation of a HE pathway was correlated with a reduction in postoperative recovery time.METHODS Patients who had unilateral elective lower limb orthopedic procedures through the T and HE pathway were screened between 2017 to 2019.Patients were at least 18 years old,and American Society of Anesthesiologists(ASA)Physical Status I to III without major systemic comorbidities were included.Propensity score was generated using multivariable regression taking age,body mass index,sex,ASA class and surgical type as covariates using nearest neighbour methods between the two pathways.Mann Whitney U test were used to analyzed total postoperative time.RESULTS There was an associated reduction in total postoperative recovery time of 63 minutes(95%CI:-69 to-57)in the HE group.The operating room time and total length of stay also had an associated decrease of 20 minutes(95%CI:-23 to-17)and 84 minutes(95%CI:-92 to-75)respectively.CONCLUSION Utilizing multifaceted strategies to improve perioperative efficiency was associated with a reduction in the postoperative recovery time in our retrospective study.This model can be a potential strategy to deal with surgical backlog in the face of ongoing human resource challenges.
文摘This study takes the panel data of 278 prefecture-level cities in China from 2011 to 2022 as samples,constructs a super-efficiency SBM model to measure urban energy-environment efficiency,uses the entropy method to synthesize the digital economy composite index,and introduces the green innovation index as a mediating variable.Breaking through the traditional analysis framework in the empirical method:Firstly,through the fixed-effects model and mediating-effect test,it reveals the direct impact of the digital economy on energy-environment efficiency and the transmission path of green innovation.Secondly,it divides the eastern,central,and western regions and low-carbon pilot cities for heterogeneity tests to identify the moderating effect of policy intervention.Thirdly,it strengthens the robustness of the conclusions by replacing the super-efficiency CCR model,shortening the sample period,and performing winsorization.The study finds that the digital economy significantly improves energy-environment efficiency through green technology innovation.These conclusions provide an empirical basis for optimizing the layout of digital infrastructure and improving the regional collaborative emission-reduction mechanism.
文摘The growing need for sustainable energy solutions,driven by rising energy shortages,environmental concerns,and the depletion of conventional energy sources,has led to a significant focus on renewable energy.Solar energy,among the various renewable sources,is particularly appealing due to its abundant availability.However,the efficiency of commercial solar photovoltaic(PV)modules is hindered by several factors,notably their conversion efficiency,which averages around 19%.This efficiency can further decline to 10%–16%due to temperature increases during peak sunlight hours.This study investigates the cooling of PV modules by applying water to their front surface through Computational fluid dynamics(CFD).The study aimed to determine the optimal conditions for cooling the PV module by analyzing the interplay between water film thickness,Reynolds number,and their effects on temperature reduction and heat transfer.The CFD analysis revealed that the most effective cooling condition occurred with a 5 mm thick water film and a Reynolds number of 10.These specific parameters were found to maximize the heat transfer and temperature reduction efficiency.This finding is crucial for the development of practical and efficient cooling systems for PV modules,potentially leading to improved performance and longevity of solar panels.Alternative cooling fluids or advanced cooling techniques that might offer even better efficiency or practical benefits.
文摘The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to the TiO 2/UV photocatalysis system. Furthermore, for the immobility system (IS), the formulation of the faction of light absorbed by the TiO 2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity (T). For the suspension system(SS), due to the difficulty to obtain the absorption coefficient ( α ) of TiO 2 particulates, the quantum efficiency is calculated by means of the relative photonic efficiency ( ζ r) and the standard quantum yield ( Φ standard ).
文摘The study measures productive efficiency of tomato growers in village Akbarpura of Disctrict Nowshera in Khyber Pakhtunkhwa （KPK） province of Northern Pakistan. The study uses household level data collected in summer 2010 from sample farmers selected by multi-staged sampling. The study uses a theoretical framework to measure productive efficiency and estimates the Cobb-Douglas frontier production and cost models. The study found that technical efficiency indices varied significantly, with technical efficiency index averaging at 65%. The indices of allocative efficiency also varied widely, with an average of 56%. There was a wide gap between the highest and lowest economic efficiency indices, with a mean economic efficiency of 35%. The study concluded that farmer education, extension visits, age and access to credit contributed significantly and positively to productive efficiencies. A policy implication of this study is that there is enough potential for farmers to increase tomato production and net profits. The study recommends that the government should further invest in public education and strengthen extension services farmer education and because extension visits constituted important determinants of productive efficiencies.
基金National Nonprofit Institute Research Grant of CAF,No.CAFYBB2018ZA004,No.CAFYBB2023ZA009Fengyun Application Pioneering Project,No.FY-APP-ZX-2023.02。
文摘Water use efficiency(WUE),as a pivotal indicator of the coupling degree within the carbon–water cycle of ecosystems,holds considerable importance in assessment of the carbon–water balance within terrestrial ecosystems.However,in the context of global warming,WUE evolution and its primary drivers on the Tibetan Plateau remain unclear.This study employed the ensemble empirical mode decomposition method and the random forest algorithm to decipher the nonlinear trends and drivers of WUE on the Tibetan Plateau in 2001–2020.Results indicated an annual mean WUE of 0.8088 gC/mm·m^(2)across the plateau,with a spatial gradient reflecting decrease from the southeast toward the northwest.Areas manifesting monotonous trends of increase or decrease in WUE accounted for 23.64%and 9.69%of the total,respectively.Remarkably,66.67%of the region exhibited trend reversals,i.e.,39.94%of the area of the Tibetan Plateau showed transition from a trend of increase to a trend of decrease,and 26.73%of the area demonstrated a shift from a trend of decrease to a trend of increase.Environmental factors accounted for 70.79%of the variability in WUE.The leaf area index and temperature served as the major driving forces of WUE variation.
基金supported by the Natural Science Fund of China(31771724)the Key Research and Development Project of Shaanxi Province(2024NC-ZDCYL-01-10).
文摘The increase in soil temperature associated with climate change has introduced considerable challenges to crop production.Split nitrogen application(SN)represents a potential strategy for improving crop nitrogen use efficiency and enhancing crop stress resistance.Nevertheless,the precise interaction between soil warming(SW)and SN remains unclear.In order to ascertain the impact of SW on maize growth and whether SN can improve the tolerance of maize to SW,a two-year field experiment was conducted(2022-2023).The aim was to examine the influence of two SW ranges(MT,warming 1.40℃;HT,warming 2.75℃)and two nitrogen application methods(N1,one-time basal application of nitrogen fertilizer;N2,one third of base nitrogen fertilizer+two thirds of jointing stage supplemental nitrogen fertilizer)on maize root growth,photosynthetic characteristics,nitrogen use efficiency,and yield.The results demonstrated that SW impeded root growth and precipitated the premature aging of maize leaves following anthesis,particularly in the HT,which led to a notable reduction in maize yield.In comparison to N1,SN has been shown to increase root length density by 8.54%,root bleeding rate by 8.57%,and enhance root distribution ratio in the middle soil layers(20-60 cm).The interaction between SW and SN had a notable impact on maize growth and yield.The SN improved the absorption and utilization efficiency of nitrogen by promoting root development and downward canopy growth,thus improving the tolerance of maize to SW at the later stage of growth.In particular,the N2HT resulted in a 14.51%increase in the photosynthetic rate,a 18.58%increase in nitrogen absorption efficiency,and a 18.32%increase in maize yield compared with N1HT.It can be posited that the SN represents a viable nitrogen management measure with the potential to enhance maize tolerance to soil high-temperature stress.
基金The financial support from the National Natural Science Foundation of China(22127812,22278433,22178379)the National Key Research and Development Program of China(2021YFC2800902)are gratefully acknowledged。
文摘The mechanism of hydrate-based desalination is that water molecules would transfer to the hydrate phase during gas hydrate formation process,while the salt ions would be conversely concentrated in the unreacted saltwater.However,the salt concentration of hydrate decomposed water and the desalination degree of hydrate phase are still unclear.The biggest challenge is how to effectively separate the hydrate phase and the remaining unreacted salt water,and then decompose the hydrate phase to measure the salt concentration of hydrate melt water.This work developed an apparatus and pressure-driven filtration method to efficiently separate the hydrate phase and the remaining unreacted saltwater.On this basis,the single hydrate phase was obtained,then it was dissociated and the salt concentration of hydrate melt water was measured.The experimental results demonstrate that when the initial salt mass concentration is 0.3% to 8.0%,the salt removal efficiency for NaCl solution is 15.9% to 29.8%by forming CO_(2) hydrate,while for CaCl_(2) solution is 28.9%to 45.5%.The solute CaCl_(2) is easier to be removed than solute NaCl.In addition,the salt removal efficiency for forming CO_(2) hydrate is higher than that for forming methane hydrate.The multi-stage desalination can continuously decrease the salt concentration of hydrate dissociated water,and the salt removal efficiency per stage is around 20%.
基金supported by the National Key Research and Development Program of China (2021YFD1901200)the Key Research and Development Program of Hubei Province of China (2023BBB028)+1 种基金the Earmarked Fund of Hubei province of Chinathe Fundamental Research Funds for the Central Universities (2662024ZKQD005)
文摘The effects of micro-ridge-furrow planting(MR)on yield and the efficiency of light,water,and thermal resource use in rapeseed were tested in a three-year field experiment comparing MR to conventional flat planting.MR enhanced canopy heterogeneity by altering the leaf angle between plants on ridges and furrows.The heterogeneous canopy environment increased intercepted photosynthetic active radiation,alleviated canopy temperature stress,and optimized canopy humidity,leading to improvements in light-nitrogen matching and net photosynthetic rate.Consequently,dry matter and yield increased by 13.0%and 11.0%,respectively,while radiation,thermal,and precipitation utilization efficiency increased by 12.3%-16.2%.The corresponding improvements in yield and resource use efficiency were attributed to a heterogeneous canopy environment that improved microclimatic conditions.
基金supported by research grants from the Natural Science Foundation of Shandong Province,China(ZR2020MC092)the Key Research and Development Project of Shandong Province,China(2019TSCYCX-33)the Key Research and Development Project of Shandong Province,China(LJNY202025).
文摘To make agricultural systems sustainable in terms of their greenness and efficiency,optimizing the tillage and fertilization practices is essential.To assess the effects of tilling and fertilization practices in wheat-maize cropping systems,a three-year field experiment was designed to quantify the carbon footprint(CF)and energy efficiency of the cropping systems in the North China Plain.The study parameters included four tillage practices(no tillage(NT),conventional tillage(CT),rotary tillage(RT),and subsoiling rotary tillage(SRT))and two fertilizer regimes(inorganic fertilizer(IF)and hybrid fertilizer with organic and inorganic components(HF)).The results indicated that the most prominent energy inputs and greenhouse gas(GHG)emissions could be ascribed to the use of fertilizers and fuel consumption.Under the same fertilization regime,ranking the tillage patterns with respect to the value of the crop yield,profit,CF,energy use efficiency(EUE)or energy productivity(EP)for either wheat or maize always gave the same sequence of SRT>RT>CT>NT.For the same tillage,the energy consumption associated with HF was higher than IF,but its GHG emissions and CF were lower while the yield and profit were higher.In terms of overall performance,tilling is more beneficial than NT,and reduced tillage practices(RT and SRT)are more beneficial than CT.The fertilization regime with the best overall performance was HF.Combining SRT with HF has significant potential for reducing CF and increasing EUE,thereby improving sustainability.Adopting measures that promote these optimizations can help to overcome the challenges posed by a lack of food security,energy crises and ecological stress.
基金supported by the National Natural Science Foundation of China(Grant Nos.U22A20202 and 52275477).
文摘Trochoidal milling is known for its advantages in machining difficult-to-machine materials as it facilitates chip removal and tool cooling.However,the conventional trochoidal tool path presents challenges such as lower machining efficiency and longer machining time due to its time-varying cutter-workpiece engagement angle and a high percentage of non-cutting tool paths.To address these issues,this paper introduces a parameter-variant trochoidal-like(PVTR)tool path planning method for chatter-free and high-efficiency milling.This method ensures a constant engagement angle for each tool path period by adjusting the trochoidal radius and step.Initially,the nonlinear equation for the PVTR toolpath is established.Then,a segmented recurrence method is proposed to plan tool paths based on the desired engagement angle.The impact of trochoidal tool path parameters on the engagement angle is analyzed and coupled this information with the milling stability model based on spindle speed and engagement angle to determine the desired engagement angle throughout the machining process.Finally,several experimental tests are carried out using the bull-nose end mill to validate the feasibility and effectiveness of the proposed method.
基金financially supported by a National Research Foundation of Korea(NRF)grant funded by the Korean government(No.2016R1A3B1908249,RS202400407199).
文摘Although phase-change random-access memory(PCRAM)is a promising next-generation nonvolatile memory technology,challenges remain in terms of reducing energy consumption.This is primarily be-cause the high thermal conductivities of phase-change materials(PCMs)promote Joule heating dissi-pation.Repeated phase transitions also induce long-range atomic diffusion,limiting the durability.To address these challenges,phase-change heterostructure(PCH)devices that incorporate confinement sub-layers based on transition-metal dichalcogenide materials have been developed.In this study,we engi-neered a PCH device by integrating HfTe_(2),which has low thermal conductivity and excellent stability,into the PCM to realize PCRAM with enhanced thermal efficiency and structural stability.HEAT sim-ulations were conducted to validate the superior heat confinement in the programming region of the HfTe_(2)-based PCH device.Moreover,electrical measurements of the device demonstrated its outstanding performance,which was characterized by a low RESET current(∼1.6 mA),stable two-order ON/OFF ratio,and exceptional cycling endurance(∼2×10^(7)).The structural integrity of the HfTe_(2)confinement sub-layer was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy.The material properties,including electrical conductivity,cohesive energy,and electronegativity,substantiated these findings.Collectively,these results revealed that the HfTe_(2)-based PCH device can achieve significant improvements in performance and reliability compared with conventional PCRAM devices.
基金supported by the National Natural Science Foundation of China(No.92367107)。
文摘Ultra-low emission of nitrogen oxide(NO_(x))is an irreversible trend for the development of waste-to-energy industry.But traditional approaches to remove NO_(x) face significant challenge s,such as low denitration efficiency,complex denitration system,and high investment and operating cost.Here we put forward a novel polymer non-catalytic reduction(PNCR)technology that utilized a new type of polymer agent to remove NO_(x),and the proposed PNCR technology was applied to the existing waste-to-energy plant to test the denitration performance.The PNCR technology demonstrated excellent denitration performance with a NO_(x) emission concentration of<100 mg/Nm^(3) and high denitration efficiency of>75%at the temperature range of 800-900℃,which showed the application feasibility even on the complex and unstable industrial operating conditions.In addition,PNCR and hybrid polymer/selective non-catalytic reduction(PNCR/SNCR)technology possessed remarkable economic advantages including low investment fee and low operating cost of<10 CNY per ton of municipal solid waste(MSW)compared with selective catalytic reduction(SCR)technology.The excellent denitration performance of PNCR technology forebodes a broad industrial application prospect in the field of flue gas cleaning for waste-to-energy plants.
基金the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300100)the National Key Research and Development Program of China(Grant Nos.2023YFB3809600 and 2023YFC3007801)+1 种基金the National Natural Science Foundation of China(Grant Nos.62301543 and U24A20320)the Shanghai Sailing Program(Grant No.21YF1455700).
文摘Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.
基金co-supported by the National Natural Science Foundation of China(Nos.U23A20279,62271094)the National Key R&D Program of China(No.SQ2023YFB2500024)+2 种基金the Science Foundation for Youths of Natural Science Foundation of Sichuan Provincial,China(No.2022NSFSC0936)the China Postdoctoral Science Foundation(No.2022M720666)the Open Fund of Key Laboratory of Big Data Intelligent Computing,Chongqing University of Posts and Telecommunications,China(No.BDIC-2023-B-002).
文摘This work focuses on maximizing the minimum user’s security energy efficiency(SEE)in an unmanned aerial vehicle-mounted reconfigurable intelligent surface(UAV-RIS)enhanced short-packet communication(SPC)system.The base station(BS)provides short packet services to ground users using the non-orthogonal multiple access(NOMA)protocol through UAV-RIS,while preventing eavesdropper attacks.To optimize SEE,a joint optimization is performed concerning power allocation,UAV position,decoding order,and RIS phase shifts.An iterative algorithm based on block coordinate descent is proposed for mixed-integer non-convex SEE optimization problem.The original problem is decomposed into three sub-problems,solved alternately using successive convex approximation(SCA),quadratic transformation,penalty function,and semi-definite programming(SDP).Simulation results demonstrate the performance of the UAV-RIS-enhanced short-packet system under different parameters and verify the algorithm’s convergence.Compared to benchmark schemes such as orthogonal multiple access,long packet communication,and sum SEE,the proposed UAV-RIS-enhanced short-packet scheme achieves the higher minimum user’s SEE.
基金support from the National Natural Science Foundation of China(62275057)the Guangxi Natural Science Foundation(2023GXNSFFA026004 and 2022GXNSFDA035066)+2 种基金the Innovation Project of Guangxi Graduate Education(YCBZ2024034)Natural Science Foundation of Ningbo under grant(2022J149)Natural Science Foundation of Ningbo under grant(2022A-230-G)
文摘Trap-assisted charge recombination is one of the primary limitationsof restricting the performance of organic solar cells. However, effectivelyreducing the presence of traps in the photoactive layer remains challenging.Herein, wide bandgap polymer donor PTzBI-dF is demonstrated as an effectivemodulator for enhancing the crystallinity of the bulk heterojunction active layerscomposed of D18 derivatives blended with Y6, leading to dense and orderedmolecular packings, and thus, improves photoluminescence quenching properties.As a result, the photovoltaic devices exhibit reduced trap-assisted charge recombinationlosses, achieving an optimized power conversion efficiency of over 19%.Besides the efficiency enhancement, the devices comprised of PTzBI-dF as athird component simultaneously attain decreased current leakage, improved chargecarrier mobilities, and suppressed bimolecular charge recombination, leading toreduced energy losses. The advanced crystalline structures induced by PTzBI-dFand its characteristics, such as well-aligned energy level, and complementaryabsorption spectra, are ascribed to the promising performance improvements.Our findings suggest that donor phase engineering is a feasible approach to tuning the molecular packings in the active layer, providingguidelines for designing effective morphology modulators for high-performance organic solar cells.
基金Supported by the National Natural Science Foundation of China(61971401)。
文摘In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide.This is equivalent to including an additional inductance-capacitance for energy storage,which realizes the slow-wave effect.A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth.In the frequency band between 8-12 GHz,the measured results show that the delay multiplier of the delay line reaches 4 times,i.e.,delay line’s delay time is 4 times larger than 50Ωmicrostrip line with same length.Furthermore,the delay fluctuation,i.e.,the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%,the insertion loss is less than-2.5 dB,and the return loss is less than-15 dB.Compared with the existing delay lines,the proposed delay line has the advantages of high delay efficiency,low delay error,wide bandwidth and low loss,which has good practical value and application prospects.
