To clarify aridity/humidity status of land surface is helpful for studying environmental background and regional differences,seeking causes of environmental change,and providing a scientific basis for researches on cl...To clarify aridity/humidity status of land surface is helpful for studying environmental background and regional differences,seeking causes of environmental change,and providing a scientific basis for researches on climate change in the future.In this paper,the authors calcu-lated potential evapotranspiration of China using data from 616 meteorological stations during the period of 1971―2000 with the Penman-Monteith model recommanded by FAO in 1998.Vy-sothkii’s model was used to calculate aridity/humidity index.Then the calculated results of sta-tions were interpolated to land surface using ArcGIS.Results show that the annual average po-tential evapotranspiration is 400―1500 mm in the whole country,600―800 mm in most parts of it;and 350―1400 mm in growing season(April―Octobor),which is nearly 200 mm less than the annual average.According to the aridity/humidity indexes of 1.0,1.5 and 4.0,the aridity/humidity status is categorized to four types,namely,humid,subhumid,semiarid and arid.A majority of stations(76%)are more humid in growing season than the annual average.Results of com-prisons between the distribution map of aridity/humidity index with that of precipitation and vegetation indicate a good consistence of aridity/humidity status with natural environment.Therefore potential evapotranspiration calculated with modified FAO’s Penman-Monteith model in combination with aridity/humidity index that considers water balance can more reasonably explain the actual land surface aridity/humidity status of China.展开更多
The growing demand for personalized health care,smart wearables,and advanced environmental monitoring has spurred the development of multifunctional materials that combine flexibility,environmental adaptability,and di...The growing demand for personalized health care,smart wearables,and advanced environmental monitoring has spurred the development of multifunctional materials that combine flexibility,environmental adaptability,and diverse functionalities.However,conventional materials often failed to integrate these attributes simultaneously,hindering their applicability in next-generation technologies.Here,we present an organic-inorganic hybrid crystalline material with a unique sandwich-like architecture,in which a flexible organic crystal core is encased by reduced graphene oxide(rGO)and thermoplastic polyurethane(TPU).This strategic integration endows the material with fluorescence,cryogenic flexibility,and electrical conductivity,while also enabling dual sensing and actuation capabilities.The rGO layer facilitates real-time humidity(25-90%RH)and temperature(25-180℃)sensing through environmental interactions,whereas the differential thermal expansion between TPU and the flexible crystal core drives efficient photothermal actuation at-150℃for advanced thermal regulation.The hybrid material exhibits stable performance under extreme conditions,making it a promising candidate for biomedical monitoring,flexible electronics,and energy applications.This work establishes hybrid crystalline materials as versatile and scalable platforms for addressing complex technological demands,paving the way for their application in next-generation multifunctional devices.展开更多
The meteorological data of 616 stations in China were used to calculate the potential evapotranspira-tion and aridity/humidity index by applying the modified FAO-Penman-Monteith model. Regional difference of trends in...The meteorological data of 616 stations in China were used to calculate the potential evapotranspira-tion and aridity/humidity index by applying the modified FAO-Penman-Monteith model. Regional difference of trends in precipitation, potential evapotranspiration and arid-ity/humidity index over China and their interdecadal varia-tions were analyzed from 1971 to 2000. The results show that all the four climatic factors trends have obvious regional difference and interdecadal variations. Annual precipitation during the 30-year period shows an increasing trend over most regions of China, with decreasing trends in potential evapotranspiration and aridity/humidity index. Most regions in China become more humid, especially significant in northern Xinjiang, eastern Tibet, western Sichuan, and northern Yunnan. The average value over China would mask the regional difference of climate change because of the com-plex environmental condition in China. Therefore regional difference should be analyzed to further understand climate change and its impacts. Both water supply and demand need to be considered when attempting to study regional arid-ity/humidity conditions.展开更多
The effect of external roof shading on the spatial distribution of air temperature and relative humidity in a greenhouse(Tin and RHin) was evaluated under the arid climatic conditions of Riyadh City, Saudi Arabia. Two...The effect of external roof shading on the spatial distribution of air temperature and relative humidity in a greenhouse(Tin and RHin) was evaluated under the arid climatic conditions of Riyadh City, Saudi Arabia. Two identical, evaporatively-cooled, single-span greenhouses were used in the experiment. One greenhouse was externally shaded(Gs) using a movable black plastic net(30% transmissivity), and the other greenhouse was kept without shading(Gc). Strawberry plants were cultivated in both greenhouses. The results showed that the spatial distribution of the Tin and RHin was significantly affected by the outside solar radiation and evaporative cooling operation. The regression analysis showed that when the outside solar radiation intensity increased from 200 to 800 W m–2, the Tin increased by 4.5℃ in the Gc and 2℃in the Gs, while the RHin decreased by 15% in the Gc and 5% in the Gs, respectively. Compared with those in the Gc, more uniformity in the spatial distribution of the Tin and RHin was observed in the Gs. The difference between the maximum and minimum Tin of 6.4℃ and the RHin of 10% was lower in the Gs than those in the Gc during the early morning. Around 2℃ difference in the Tin was shown between the area closed to the exhausted fans and the area closed to the cooling pad with the external shading. In an evaporatively-cooled greenhouse in arid regions, the variation of the Tin and RHin in the vertical direction and along the sidewalls was much higher than that in the horizontal direction. The average variation of the Tin and RHin in the vertical direction was 5.2℃ and 10% in the Gc and 5.5℃ and 13% in the Gs, respectively. The external shading improved the spatial distribution of the Tin and RHin and improved the cooling efficiency of the evaporative cooling system by 12%, since the transmitted solar radiation and accumulated thermal energy in the greenhouse were significantly reduced.展开更多
Playing an important role in global warming and plant growth,relative humidity(RH)has profound impacts on production and living,and can be used as an integrated indicator for evaluating the wet-dry conditions in the a...Playing an important role in global warming and plant growth,relative humidity(RH)has profound impacts on production and living,and can be used as an integrated indicator for evaluating the wet-dry conditions in the arid and semi-arid area.However,information on the spatial-temporal variation and the influencing factors of RH in these regions is still limited.This study attempted to use daily meteorological data during 1966–2017 to reveal the spatial-temporal characteristics of RH in the arid region of Northwest China through rotated empirical orthogonal function and statistical analysis method,and the path analysis was used to clarify the impact of temperature(T),precipitation(P),actual evapotranspiration(ETa),wind speed(W)and sunshine duration(S)on RH.The results demonstrated that climatic conditions in North Xinjiang(NXJ)was more humid than those in Hexi Corridor(HXC)and South Xinjiang(SXJ).RH had a less significant downtrend in NXJ than that in HXC,but an increasingly rising trend was observed in SXJ during the last five decades,implying that HXC and NXJ were under the process of droughts,while SXJ was getting wetter.There was a turning point for the trend of RH in Xinjiang,which occurred in 2000.Path analysis indicated that RH was negatively correlated to T,ETa,W and S,but it increased with increase of P.S,T and W had the greatest direct effects on RH in HXC,NXJ and SXJ,respectively.ETa was the factor which had the greatest indirect effect on RH in HXC and NXJ,while T was the dominant factor in SXJ.展开更多
To facilitate real-time monitoring and recording of humidity in the environment and to satisfy the requirement for strain performance in certain applications(such as wearable devices),this paper proposes an in-situ me...To facilitate real-time monitoring and recording of humidity in the environment and to satisfy the requirement for strain performance in certain applications(such as wearable devices),this paper proposes an in-situ method for synthesising Au nanoparticles on ZIF-67.In this study,an Au@ZIF-67 composite humidity-sensitive material was combined with flexible polyethylene terephthalate interdigitated electrodes to create an Au@ZIF-67 flexible humidity sensor.The prepared samples were characterised using X-ray diffraction,X-ray photoelectron spectroscopy,and transmission electron microscopy.The humidity-sensitive properties of the sensor were investigated,and its monitoring capabilities in applications involving respiration,gestures,skin,and baby diapers were tested.The experimental results indicate that compared with a pure ZIF-67 humidity sensor,the Au@ZIF-67(0.1Au@Z)flexible humidity sensor exhibits a 158.07%decrease in baseline resistance and a 51.66%increase in sensitivity to 95%relative humidity,and the hysteresis,response time,and recovery time are significantly reduced.Furthermore,the sensor exhibits excellent characteristics such as high resolution,repeatability,and stability.The obtained results regarding the material properties,humidity sensitivity,and practical application of non-contact humidity monitoring demonstrate that the prepared sensors exhibit excellent and comprehensive performance,indicating their broad prospects in wearable medical devices,wireless Internet of Things,humidity detection in complex environments,and intelligent integrated systems.展开更多
Based on ground observation data of relative humidity,the prediction performance of STNF and MIFS in each competition area during February 13-26,2024 was tested and evaluated by using two intelligent forecasting metho...Based on ground observation data of relative humidity,the prediction performance of STNF and MIFS in each competition area during February 13-26,2024 was tested and evaluated by using two intelligent forecasting methods(STNF and MIFS).The results show that STNF had better performance in forecasting relative humidity in high-altitude areas,and was suitable for fine forecasting under complex terrain.MIFS improved the short-term forecast of some low-altitude stations,but the long-term reliability was insufficient.STNF method performed better than MIFS during 0-24 h.As the prediction time extended to 24-72 h,the errors of both methods showed a systematic increase trend.STNF had higher precision,lower root mean square error and smaller mean error in most regions under the background of most weather systems,showing its superiority as a forecasting method of relative humidity.However,the precision of MIFS was slightly higher than that of STNF in Liangcheng without system background,revealing that MIFS may also be an effective option in some specific conditions.展开更多
The factors controlling dust activity and humidity in Central Asia and their relationships remain controversial,partly due to a lack of high-resolution geological records for the mid-to-late last glaciation.In this st...The factors controlling dust activity and humidity in Central Asia and their relationships remain controversial,partly due to a lack of high-resolution geological records for the mid-to-late last glaciation.In this study,we established an optically stimulated luminescence chronology for the QSHA profile in the Yili Basin,a region influenced by westerlies.Grain size and trace element data were used as paleoclimatic indicators.We investigated the relationships among Central Asian dust activity,humidity,and westerlies strength on orbital to millennial scale from 37.4 ka to 11.6 ka.Our study reveals that,on orbital timescales,humidity is positively correlated with westerlies strength which controlled by precession.Dust activity is controlled by Siberian High which was regulated by Northern Hemisphere high-latitude temperature.Their responses to low-latitude and high-latitude forcing mechanisms respectively and present an opposite relationship.On millennial timescales,humidity and westerlies strength are positively correlated.During Marine Isotope Stage(MIS)2,humidity and dust activity show synchronous fluctuations,while during MIS 3,they exhibit an inverse relationship.Westerlies strength regulated humidity,which subsequently controlled glacial activity in the Tianshan Mountains,influencing dust activity in Central Asia.Additionally,the QSHA profile recorded seven Dansgaard-Oeschger(D-O)events on millennial timescales,indicating a potential link between Central Asian dust activity and high-latitude temperature variations in the Northern Hemisphere.Our findings provide new insights into dust and humidity interaction during the last glaciation periods in Central Asia and contribute to understanding global dust and hydrological cycles.展开更多
A high humidity-resistant,dual mechanical responsive,and reversible mechanochromic wrinkling system based on a VHB 4910-polydimethylsiloxane(PDMS)substrate with a thin film consisting of 90 wt%poly(vinyl butyral)(PVB)...A high humidity-resistant,dual mechanical responsive,and reversible mechanochromic wrinkling system based on a VHB 4910-polydimethylsiloxane(PDMS)substrate with a thin film consisting of 90 wt%poly(vinyl butyral)(PVB)and 10 wt%hydroxypropyl cellulose(HPC)has been reported.The wrinkling system exhibited significant optical tuning from transparent to opaque states with 50%changes in transmittance,which was achieved through the dual mechanical modes of pre-stretching and releasing processes or bending.Upon exposure to ethanol vapor or a re-flattening process,wrinkles can be erased,yielding a transparent state.Consequently,the wrinkling system could be reversibly switched between transparency and opacity for 1000 cycles with marginal changes in the optical performance.Owing to the insolubility of PVB in water,the wrinkling patterns exhibited excellent durability in high-humidity environments(relative humidity(RH)=99%).Furthermore,the smart encryption device is also demonstrated via mechano-controlled surface topography by patterning the wrinkling system,suggesting potential applications of the designed structure in smart windows,anti-counterfeiting,dynamic display,optical information encryption,and rewritable surfaces.展开更多
High-efficiency formamidinium lead iodide(FAPbI3)-based perovskite solar cells(PSCs)typically involve annealing in humid air during the fabrication process of perovskite films.However,the combined effects of humidity ...High-efficiency formamidinium lead iodide(FAPbI3)-based perovskite solar cells(PSCs)typically involve annealing in humid air during the fabrication process of perovskite films.However,the combined effects of humidity and relatively high temperature often result in the uncontrollable formation of a detrimental PbI_(2)phase in the perovskite films.As a result,the annealing process of perovskite films is highly sensitive to the relative humidity fluctuations of the environment.Under solar illumination,the undesired PbI_(2)tends to decompose,accelerating the degradation of perovskite materials and severely compromising the light stability of PSCs.This issue is particularly critical for the buried interface and bulk of the perovskite films,as these regions absorb the majority of the incident light.Pre-treatment and posttreatment strategies are generally confined to address the PbI_(2)issues at the buried interface and on the surface of the perovskite films,respectively.However,effectively addressing the effects of excess PbI_(2)at buried interface and grain boundaries within bulk in a single step remains challenging.In this study,we propose an intermediate-treatment strategy using phthalylglycyl chloride(PTC),which involves treating the wet films with PTC prior to annealing during the formation process of the perovskite films.This approach protects the grain boundaries of polycrystalline perovskite films in advance,effectively preventing moisture-induced degradation of the perovskites and thus significantly broadening the relative humidity window of annealing process.Our results demonstrate that this strategy can successfully suppress the formation of PbI_(2)at the grain boundaries and buried interface of perovskite films,thereby eliminating the PbI_(2)-induced degradation pathways.Our strategy significantly reduces the sensitivity to humidity fluctuations during annealing for fabricating stable PSCs,ensuring more consistent fabrication of stable PSCs.Consequently,the resulting PSCs achieve a champion power conversion efficiency of 26.1% and demonstrate excellent light stability.展开更多
Proton exchange membrane fuel cell(PEMFC)is a promising clean energy source,but its performance and stability are vulnerable to the negative effects of humidity conditions.The gas diffusion substrate(GDS)plays a pivot...Proton exchange membrane fuel cell(PEMFC)is a promising clean energy source,but its performance and stability are vulnerable to the negative effects of humidity conditions.The gas diffusion substrate(GDS)plays a pivotal role in regulating the moisture and gas transport.The single pore structure of traditionally designed GDS often leads to the pathway competition between moisture and gas,which effects the efficiency of fuel cells.In this study,we report on a hierarchical fibrous paper with tunable hierarchical pores for a sustainable GDS.This design offers gas permeability under wet conditions,by separating the gas pathway from the moisture pathway,thus mitigating their pathway competition.In addition,this paper forms a multi-scale scaffold that absorbs moisture under high humidity conditions and releases it under dry conditions.It is allowed to maintain an optimal internal humidity and further enhances the humidity adaptability.Furthermore,the carbon footprint is only 15.97%,significantly lower than commercial alternatives.This feature makes it a sustainable solution to stabilize PEMFCs under diverse humidity conditions.展开更多
Halide solid-state electrolytes(HSSEs)with excellent ionic conductivity and high voltage stability are promising for all-solid-state Li-ion batteries(ASSLBs).However,they suffer from poor processability,mechanical dur...Halide solid-state electrolytes(HSSEs)with excellent ionic conductivity and high voltage stability are promising for all-solid-state Li-ion batteries(ASSLBs).However,they suffer from poor processability,mechanical durability and humidity stability,hindering their large-scale applications.Here,we introduce a dry-processing fibrillation strategy using hydrophobic polytetrafluoroethylene(PTFE)binder to encapsulate Li_(3)InCl_(6)(LIC)particles(the most representative HSSE).By manipulating the fibrillating process,only 0.5 wt%PTFE is sufficient to prepare free-standing LIC-PTFE(LIC-P)HSSEs.Additionally,LIC-P demonstrates excellent mechanical durability and humidity resistance.They can maintain their shapes after being exposed to humid atmosphere for 30 min,meanwhile still exhibit high ionic conductivity of>0.2m S/cm at 25℃.Consequently,the LIC-P-based ASSLBs deliver a high specific capacity of 126.6 m Ah/g at0.1 C and long cyclability of 200 cycles at 0.2 C.More importantly,the ASSLBs using moisture-exposed LIC-P can still operate properly by exhibiting a high capacity-retention of 87.7%after 100 cycles under0.2 C.Furthermore,for the first time,we unravel the LIC interfacial morphology evolution upon cycling because the good mechanical durability enables a facile separation of LIC-P from ASSLBs after testing.展开更多
Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity ...Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity sensing properties of Cu-Mg-Zn ferrites with rare earth element doping were investigated.Single-phase cubic spinel structure was confirmed via X-ray diffraction(XRD),and the crystal size ranges fro m 22.12 to 63.17 nm according to the Scherrer formula and from 25.66 to 67.46 nm according to the Williamson-Hall method.Po rous structure and elemental characterization of the samples were investigated by scanning electron microscopy(SEM).The optic band gap varies between 2.21 and 2.49 eV.Electrical measurements were conducted in the frequency range of 1 Hz-20 MHz and temperature range of 25-400℃.It has been determined that the dielectric results are consistent with the Maxwell-Wagner method and exhibit a non-Debye relaxation model,as observed from the Nyquist plots.At a minimum frequency value of 1 Hz,the dielectric constants for pure,Ce,Sr,and La samples are 9×10^(4),5×10^(4),1×10^(8),and 2×10^(5) at 25℃,and 1.85×10^(8),1.34×10^(8),1.15×10^(10),and 4.4×10^(8)at 400℃.In the same order,for the maximum frequency value of 20 MHz,the dielectric constants at 25℃are 169,166,3799,and 60,while at 400℃they are 734,624,12108,and 774.The La doped sample's low dielectric loss makes it suitable for high-frequency applications.Humidity measurements were performed at room temperature and in the 5%-95%relative humidity range.The humidity properties of the samples were investigated through humidity mapping,sensitivity,hysteresis,and long-term stability tests.Compared to other samples,the results indicate that Ce exhibits better humidity performance with 99%sensitivity and the highest repeatability(91.2%).These results show that Ce-doped ferrite can be used as a low-cost,high-performance humidity sensor.展开更多
This paper presents a multi-scale experimental investigation of the weathering degradation of red mudstone.Natural rocks were extracted from the surface ground to 120 m,inwhich three sets of samples were selected to c...This paper presents a multi-scale experimental investigation of the weathering degradation of red mudstone.Natural rocks were extracted from the surface ground to 120 m,inwhich three sets of samples were selected to consider the different initial rock fabrics.The long-term relative humidity(RH)cycles under two amplitudes were imposed on red mudstone to simulate the weathering process.After RH cycles,a series of uniaxial compression tests,Brazilian splitting tests and bender-extender element tests were carried out to examine the reduction in strength and stiffness.The objective of this study is to develop an extended stress-volume framework characterizing the degradation of natural red mudstone both at microscale and macroscale.Accompanied by the irreversible swelling of the rock specimen is the progressive degradation of strength,stiffness and Poisson's ratio.A unified exponential degradation model in terms of the irreversible volumetric strain was thus proposed to capture such a degradation pattern.The effect of the initial rock fabric was evident.The highest degradation rate and potential were identified in slightly weathered specimens.Significant slaking of aggregates and crack propagation were confirmed by scanning electron microscope(SEM)micrographs,which were considered as the main consequence of structure damage leading to degradation of mechanical properties.The structure damage during RH cycles denoted the hysteresis nature in the response to the cycling hydraulic reaction,in turn causing the increase in volumetric strain.Thus,the stress-volume relation rather than the suction relation was found in more reasonable agreement with the experimental results.展开更多
Monolithic catalysts with excellent O_(3)catalytic decomposition performance were prepared by in situ loading of Co-doped KMn_(8)O_(16)on the surface of nickel foam.The triple-layer structure with Co-doped KMn_(8)O_(1...Monolithic catalysts with excellent O_(3)catalytic decomposition performance were prepared by in situ loading of Co-doped KMn_(8)O_(16)on the surface of nickel foam.The triple-layer structure with Co-doped KMn_(8)O_(16)/Ni6MnO_(8)/Ni foam was grown spontaneously on the surface of nickel foam by tuning the molar ratio of KMnO_(4)to Co(NO_(3))_(2)·6H_(2)O precursors.Importantly,the formed Ni6MnO_(8)structure between KMn_(8)O_(16)and nickel foam during in situ synthesis process effectively protected nickel foam from further etching,which significantly enhanced the reaction stability of catalyst.The optimum amount of Co doping in KMn_(8)O_(16)was available when the molar ratio of Mn to Co species in the precursor solution was 2:1.And the Mn2Co1 catalyst had abundant oxygen vacancies and excellent hydrophobicity,thus creating outstanding O_(3)decomposition activity.The O_(3)conversion under dry conditions and relative humidity of 65%,90%over a period of 5 hr was 100%,94%and 80%with the space velocity of 28,000 hr^(−1),respectively.The in situ constructed Co-doped KMn_(8)O_(16)/Ni foam catalyst showed the advantages of low price and gradual applicability of the preparation process,which provided an opportunity for the design of monolithic catalyst for O_(3)catalytic decomposition.展开更多
As an indispensable part of modern buildings,centralized central air conditioning systems play an important role in maintaining the comfort and air quality of the indoor environment.However,with the increasing energy ...As an indispensable part of modern buildings,centralized central air conditioning systems play an important role in maintaining the comfort and air quality of the indoor environment.However,with the increasing energy consumption,how to improve the energy efficiency ratio of air conditioning systems and reduce energy consumption has become an important issue in research and practice.The purpose of this paper is to discuss the impact of humidity control strategies on energy saving in centralized central air conditioning systems,with a view to providing a theoretical basis and practical guidance for realizing building energy efficiency.展开更多
The large dynamic range and high performance of temperature and humidity profile lidar made it a popular tool for monitoring the atmospheric environment.In this study,we carried out an accurate analysis of the key com...The large dynamic range and high performance of temperature and humidity profile lidar made it a popular tool for monitoring the atmospheric environment.In this study,we carried out an accurate analysis of the key components of the lidar system,including lasers,the emitting and receiving light paths,and photodetectors.We combined the validation of simulations with experimental testing,and then the applicability indicators and necessary conditions in accordance were suggested.For the frequency stability of the laser,when the wavelength shift is less than 0.15%,the measurement accuracy of the system can be guaranteed to be less than 5%.The degree of near-field signal distortion will be significantly impacted by the size of the geometric factor’s transition zone.The introduced measurement error is less than 2%when the deviation angle of the emission axis is less than 0.1 mrad.It has been tested that selecting a low-sensitivity detector can help to improve the sensitivity of temperature detection since this channel is sensitive to the detector’s nonlinearity.To enhance lidar’s detection capabilities and direct the lidar system design process,it is beneficial to analyze the precision of the key components.展开更多
This paper presents a thermophysical study approach for a pure environmental control system(ECS),incorporating the geometric dimensions of heat exchangers,ram air duct,and air cycle machine(ACM)blades of the Sabreline...This paper presents a thermophysical study approach for a pure environmental control system(ECS),incorporating the geometric dimensions of heat exchangers,ram air duct,and air cycle machine(ACM)blades of the Sabreliner’s environmental control system.Real flight scenarios are simulated by considering flight input variables such as altitude,aircraft speed,compression ratio of the air cycle machine,and the mass flow rate of bleed air.The study evaluates the coefficient of performance(COP)of the environmental control system,the heat exchanger efficiencies,and the work distribution of the air cycle machine based on five flight scenarios,with a particular focus on considering the effects of humidity on environmental control system performance.The results demonstrate that at cruising altitude(11,000 m),air humidity conditions allow an increase in the COP of around 9.28%compared to dry conditions.Conversely,on land,humidity conditions reduce the performance by 4.26%compared to dry conditions.It was also found that the effects of humidity at high aircraft speeds become negligible.In general terms,the humidity conditions in the air proved to have positive effects on the environmental control system’s performance but negative effects on the heat exchanger efficiencies,reducing them by 0.22%.Additionally,land conditions reflect significant improvements in performance when the compression ratio of the air cycle machine is varied.Furthermore,in the work distribution of the air cycle machine,humidity conditions were demonstrated to consume 2.91%less work fromthe turbine compared to dry conditions.展开更多
Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis t...Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.40171040)the Knowledge Innovation Project of the Institute of Geographical Sciences and Natural Resources Research,CAS(Grant No.CXIOG-A02-03)the Director Foundation of Knowledge Innovation Project of CAS(Grant No.SJ10G-A00-06).
文摘To clarify aridity/humidity status of land surface is helpful for studying environmental background and regional differences,seeking causes of environmental change,and providing a scientific basis for researches on climate change in the future.In this paper,the authors calcu-lated potential evapotranspiration of China using data from 616 meteorological stations during the period of 1971―2000 with the Penman-Monteith model recommanded by FAO in 1998.Vy-sothkii’s model was used to calculate aridity/humidity index.Then the calculated results of sta-tions were interpolated to land surface using ArcGIS.Results show that the annual average po-tential evapotranspiration is 400―1500 mm in the whole country,600―800 mm in most parts of it;and 350―1400 mm in growing season(April―Octobor),which is nearly 200 mm less than the annual average.According to the aridity/humidity indexes of 1.0,1.5 and 4.0,the aridity/humidity status is categorized to four types,namely,humid,subhumid,semiarid and arid.A majority of stations(76%)are more humid in growing season than the annual average.Results of com-prisons between the distribution map of aridity/humidity index with that of precipitation and vegetation indicate a good consistence of aridity/humidity status with natural environment.Therefore potential evapotranspiration calculated with modified FAO’s Penman-Monteith model in combination with aridity/humidity index that considers water balance can more reasonably explain the actual land surface aridity/humidity status of China.
基金support from the National Natural Science Foundation of China(52373181 and 52173164)the Natural Science Foundation of Jilin Province(20250102120JC and 20230101038JC)+1 种基金the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20240259)the Project funded by China Postdoctoral Science Foundation(2024M761121 and 2025T180139).
文摘The growing demand for personalized health care,smart wearables,and advanced environmental monitoring has spurred the development of multifunctional materials that combine flexibility,environmental adaptability,and diverse functionalities.However,conventional materials often failed to integrate these attributes simultaneously,hindering their applicability in next-generation technologies.Here,we present an organic-inorganic hybrid crystalline material with a unique sandwich-like architecture,in which a flexible organic crystal core is encased by reduced graphene oxide(rGO)and thermoplastic polyurethane(TPU).This strategic integration endows the material with fluorescence,cryogenic flexibility,and electrical conductivity,while also enabling dual sensing and actuation capabilities.The rGO layer facilitates real-time humidity(25-90%RH)and temperature(25-180℃)sensing through environmental interactions,whereas the differential thermal expansion between TPU and the flexible crystal core drives efficient photothermal actuation at-150℃for advanced thermal regulation.The hybrid material exhibits stable performance under extreme conditions,making it a promising candidate for biomedical monitoring,flexible electronics,and energy applications.This work establishes hybrid crystalline materials as versatile and scalable platforms for addressing complex technological demands,paving the way for their application in next-generation multifunctional devices.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 40171040)；the KnowledgeInnovation Project of the Institute of Geographical Sciences and Natural Resources Research, CAS (Grant No. CXIOG-A02-03)； the Director Foundation of Knowledge Innovation Project of CAS (Grant No.SJ10G-A00-06).
文摘The meteorological data of 616 stations in China were used to calculate the potential evapotranspira-tion and aridity/humidity index by applying the modified FAO-Penman-Monteith model. Regional difference of trends in precipitation, potential evapotranspiration and arid-ity/humidity index over China and their interdecadal varia-tions were analyzed from 1971 to 2000. The results show that all the four climatic factors trends have obvious regional difference and interdecadal variations. Annual precipitation during the 30-year period shows an increasing trend over most regions of China, with decreasing trends in potential evapotranspiration and aridity/humidity index. Most regions in China become more humid, especially significant in northern Xinjiang, eastern Tibet, western Sichuan, and northern Yunnan. The average value over China would mask the regional difference of climate change because of the com-plex environmental condition in China. Therefore regional difference should be analyzed to further understand climate change and its impacts. Both water supply and demand need to be considered when attempting to study regional arid-ity/humidity conditions.
文摘The effect of external roof shading on the spatial distribution of air temperature and relative humidity in a greenhouse(Tin and RHin) was evaluated under the arid climatic conditions of Riyadh City, Saudi Arabia. Two identical, evaporatively-cooled, single-span greenhouses were used in the experiment. One greenhouse was externally shaded(Gs) using a movable black plastic net(30% transmissivity), and the other greenhouse was kept without shading(Gc). Strawberry plants were cultivated in both greenhouses. The results showed that the spatial distribution of the Tin and RHin was significantly affected by the outside solar radiation and evaporative cooling operation. The regression analysis showed that when the outside solar radiation intensity increased from 200 to 800 W m–2, the Tin increased by 4.5℃ in the Gc and 2℃in the Gs, while the RHin decreased by 15% in the Gc and 5% in the Gs, respectively. Compared with those in the Gc, more uniformity in the spatial distribution of the Tin and RHin was observed in the Gs. The difference between the maximum and minimum Tin of 6.4℃ and the RHin of 10% was lower in the Gs than those in the Gc during the early morning. Around 2℃ difference in the Tin was shown between the area closed to the exhausted fans and the area closed to the cooling pad with the external shading. In an evaporatively-cooled greenhouse in arid regions, the variation of the Tin and RHin in the vertical direction and along the sidewalls was much higher than that in the horizontal direction. The average variation of the Tin and RHin in the vertical direction was 5.2℃ and 10% in the Gc and 5.5℃ and 13% in the Gs, respectively. The external shading improved the spatial distribution of the Tin and RHin and improved the cooling efficiency of the evaporative cooling system by 12%, since the transmitted solar radiation and accumulated thermal energy in the greenhouse were significantly reduced.
基金This study was supported by the National Natural Science Foundation of China(U1703241)the Key International Cooperation Project of Chinese Academy of Sciences(121311KYSB20160005)the Open Project of Xinjiang Uygur Autonomous Region Key Laboratory of China(2017D04010).
文摘Playing an important role in global warming and plant growth,relative humidity(RH)has profound impacts on production and living,and can be used as an integrated indicator for evaluating the wet-dry conditions in the arid and semi-arid area.However,information on the spatial-temporal variation and the influencing factors of RH in these regions is still limited.This study attempted to use daily meteorological data during 1966–2017 to reveal the spatial-temporal characteristics of RH in the arid region of Northwest China through rotated empirical orthogonal function and statistical analysis method,and the path analysis was used to clarify the impact of temperature(T),precipitation(P),actual evapotranspiration(ETa),wind speed(W)and sunshine duration(S)on RH.The results demonstrated that climatic conditions in North Xinjiang(NXJ)was more humid than those in Hexi Corridor(HXC)and South Xinjiang(SXJ).RH had a less significant downtrend in NXJ than that in HXC,but an increasingly rising trend was observed in SXJ during the last five decades,implying that HXC and NXJ were under the process of droughts,while SXJ was getting wetter.There was a turning point for the trend of RH in Xinjiang,which occurred in 2000.Path analysis indicated that RH was negatively correlated to T,ETa,W and S,but it increased with increase of P.S,T and W had the greatest direct effects on RH in HXC,NXJ and SXJ,respectively.ETa was the factor which had the greatest indirect effect on RH in HXC and NXJ,while T was the dominant factor in SXJ.
基金supported by the Natural Science Project of Zhengzhou Science and Technology Bureau(No.21ZZXTCX12)the Key Research and Development Program of Henan Province(No.221111220300)+1 种基金the Key Program of the National Natural Science Foundation of China(No.62333013)the Youth Backbone Teacher Training Program of Henan University of Technology(No.21420154).
文摘To facilitate real-time monitoring and recording of humidity in the environment and to satisfy the requirement for strain performance in certain applications(such as wearable devices),this paper proposes an in-situ method for synthesising Au nanoparticles on ZIF-67.In this study,an Au@ZIF-67 composite humidity-sensitive material was combined with flexible polyethylene terephthalate interdigitated electrodes to create an Au@ZIF-67 flexible humidity sensor.The prepared samples were characterised using X-ray diffraction,X-ray photoelectron spectroscopy,and transmission electron microscopy.The humidity-sensitive properties of the sensor were investigated,and its monitoring capabilities in applications involving respiration,gestures,skin,and baby diapers were tested.The experimental results indicate that compared with a pure ZIF-67 humidity sensor,the Au@ZIF-67(0.1Au@Z)flexible humidity sensor exhibits a 158.07%decrease in baseline resistance and a 51.66%increase in sensitivity to 95%relative humidity,and the hysteresis,response time,and recovery time are significantly reduced.Furthermore,the sensor exhibits excellent characteristics such as high resolution,repeatability,and stability.The obtained results regarding the material properties,humidity sensitivity,and practical application of non-contact humidity monitoring demonstrate that the prepared sensors exhibit excellent and comprehensive performance,indicating their broad prospects in wearable medical devices,wireless Internet of Things,humidity detection in complex environments,and intelligent integrated systems.
文摘Based on ground observation data of relative humidity,the prediction performance of STNF and MIFS in each competition area during February 13-26,2024 was tested and evaluated by using two intelligent forecasting methods(STNF and MIFS).The results show that STNF had better performance in forecasting relative humidity in high-altitude areas,and was suitable for fine forecasting under complex terrain.MIFS improved the short-term forecast of some low-altitude stations,but the long-term reliability was insufficient.STNF method performed better than MIFS during 0-24 h.As the prediction time extended to 24-72 h,the errors of both methods showed a systematic increase trend.STNF had higher precision,lower root mean square error and smaller mean error in most regions under the background of most weather systems,showing its superiority as a forecasting method of relative humidity.However,the precision of MIFS was slightly higher than that of STNF in Liangcheng without system background,revealing that MIFS may also be an effective option in some specific conditions.
基金supported by the Natural Science Foundation of China(Grant Nos.42372220,42172207)the Youth Innovation Promotion Association Chinese Academy of Sciences(Grant No.Y2022102)+1 种基金the Science and Technology Innovation Project of Laoshan Laboratory(Grant No.LSKJ202203300)the International Partnership Program of the Chinese Academy of Sciences.
文摘The factors controlling dust activity and humidity in Central Asia and their relationships remain controversial,partly due to a lack of high-resolution geological records for the mid-to-late last glaciation.In this study,we established an optically stimulated luminescence chronology for the QSHA profile in the Yili Basin,a region influenced by westerlies.Grain size and trace element data were used as paleoclimatic indicators.We investigated the relationships among Central Asian dust activity,humidity,and westerlies strength on orbital to millennial scale from 37.4 ka to 11.6 ka.Our study reveals that,on orbital timescales,humidity is positively correlated with westerlies strength which controlled by precession.Dust activity is controlled by Siberian High which was regulated by Northern Hemisphere high-latitude temperature.Their responses to low-latitude and high-latitude forcing mechanisms respectively and present an opposite relationship.On millennial timescales,humidity and westerlies strength are positively correlated.During Marine Isotope Stage(MIS)2,humidity and dust activity show synchronous fluctuations,while during MIS 3,they exhibit an inverse relationship.Westerlies strength regulated humidity,which subsequently controlled glacial activity in the Tianshan Mountains,influencing dust activity in Central Asia.Additionally,the QSHA profile recorded seven Dansgaard-Oeschger(D-O)events on millennial timescales,indicating a potential link between Central Asian dust activity and high-latitude temperature variations in the Northern Hemisphere.Our findings provide new insights into dust and humidity interaction during the last glaciation periods in Central Asia and contribute to understanding global dust and hydrological cycles.
基金supported by the Science and Technology Development Fund(FDCT),Macao SAR(No.0149/2022/A),and(No.0046/2024/AFJ)Guangdong Science and Technology Department(No.2023QN10C305)。
文摘A high humidity-resistant,dual mechanical responsive,and reversible mechanochromic wrinkling system based on a VHB 4910-polydimethylsiloxane(PDMS)substrate with a thin film consisting of 90 wt%poly(vinyl butyral)(PVB)and 10 wt%hydroxypropyl cellulose(HPC)has been reported.The wrinkling system exhibited significant optical tuning from transparent to opaque states with 50%changes in transmittance,which was achieved through the dual mechanical modes of pre-stretching and releasing processes or bending.Upon exposure to ethanol vapor or a re-flattening process,wrinkles can be erased,yielding a transparent state.Consequently,the wrinkling system could be reversibly switched between transparency and opacity for 1000 cycles with marginal changes in the optical performance.Owing to the insolubility of PVB in water,the wrinkling patterns exhibited excellent durability in high-humidity environments(relative humidity(RH)=99%).Furthermore,the smart encryption device is also demonstrated via mechano-controlled surface topography by patterning the wrinkling system,suggesting potential applications of the designed structure in smart windows,anti-counterfeiting,dynamic display,optical information encryption,and rewritable surfaces.
基金financially supported by the National Natural Science Foundation of China(52203208,52325310,U24A6003,52303335)the National Key R&D Program of China(2021YFB3800101)+3 种基金the Beijing Nova Program(contract no.20230484480)the open research fund of Songshan Lake Materials Laboratory(2022SLABFK07)the Yunnan Provincial Science and Technology Project at Southwest United Graduate School(202302AO370013)the R&D Fruit Fund(20210001)。
文摘High-efficiency formamidinium lead iodide(FAPbI3)-based perovskite solar cells(PSCs)typically involve annealing in humid air during the fabrication process of perovskite films.However,the combined effects of humidity and relatively high temperature often result in the uncontrollable formation of a detrimental PbI_(2)phase in the perovskite films.As a result,the annealing process of perovskite films is highly sensitive to the relative humidity fluctuations of the environment.Under solar illumination,the undesired PbI_(2)tends to decompose,accelerating the degradation of perovskite materials and severely compromising the light stability of PSCs.This issue is particularly critical for the buried interface and bulk of the perovskite films,as these regions absorb the majority of the incident light.Pre-treatment and posttreatment strategies are generally confined to address the PbI_(2)issues at the buried interface and on the surface of the perovskite films,respectively.However,effectively addressing the effects of excess PbI_(2)at buried interface and grain boundaries within bulk in a single step remains challenging.In this study,we propose an intermediate-treatment strategy using phthalylglycyl chloride(PTC),which involves treating the wet films with PTC prior to annealing during the formation process of the perovskite films.This approach protects the grain boundaries of polycrystalline perovskite films in advance,effectively preventing moisture-induced degradation of the perovskites and thus significantly broadening the relative humidity window of annealing process.Our results demonstrate that this strategy can successfully suppress the formation of PbI_(2)at the grain boundaries and buried interface of perovskite films,thereby eliminating the PbI_(2)-induced degradation pathways.Our strategy significantly reduces the sensitivity to humidity fluctuations during annealing for fabricating stable PSCs,ensuring more consistent fabrication of stable PSCs.Consequently,the resulting PSCs achieve a champion power conversion efficiency of 26.1% and demonstrate excellent light stability.
基金supported by the National Natural Science Foundation of China(Nos.U23A6005,22208112,and 32171721)the National Natural Science Foundation of China(No.22308109)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2024A1515010678)the Fundamental Research Funds for the Central Universities(SCUT:2023ZYGXZR045)the State Key Laboratory of Pulp&Paper Engineering(Nos.2023ZD01,2023C02).
文摘Proton exchange membrane fuel cell(PEMFC)is a promising clean energy source,but its performance and stability are vulnerable to the negative effects of humidity conditions.The gas diffusion substrate(GDS)plays a pivotal role in regulating the moisture and gas transport.The single pore structure of traditionally designed GDS often leads to the pathway competition between moisture and gas,which effects the efficiency of fuel cells.In this study,we report on a hierarchical fibrous paper with tunable hierarchical pores for a sustainable GDS.This design offers gas permeability under wet conditions,by separating the gas pathway from the moisture pathway,thus mitigating their pathway competition.In addition,this paper forms a multi-scale scaffold that absorbs moisture under high humidity conditions and releases it under dry conditions.It is allowed to maintain an optimal internal humidity and further enhances the humidity adaptability.Furthermore,the carbon footprint is only 15.97%,significantly lower than commercial alternatives.This feature makes it a sustainable solution to stabilize PEMFCs under diverse humidity conditions.
基金supported by the 261 Project of MIITthe National Natural Science Foundation of China(Nos.52250010,52201242,U23A20574)the Young Elite Scientists Sponsorship Program by CAST(No.2021QNRC001)。
文摘Halide solid-state electrolytes(HSSEs)with excellent ionic conductivity and high voltage stability are promising for all-solid-state Li-ion batteries(ASSLBs).However,they suffer from poor processability,mechanical durability and humidity stability,hindering their large-scale applications.Here,we introduce a dry-processing fibrillation strategy using hydrophobic polytetrafluoroethylene(PTFE)binder to encapsulate Li_(3)InCl_(6)(LIC)particles(the most representative HSSE).By manipulating the fibrillating process,only 0.5 wt%PTFE is sufficient to prepare free-standing LIC-PTFE(LIC-P)HSSEs.Additionally,LIC-P demonstrates excellent mechanical durability and humidity resistance.They can maintain their shapes after being exposed to humid atmosphere for 30 min,meanwhile still exhibit high ionic conductivity of>0.2m S/cm at 25℃.Consequently,the LIC-P-based ASSLBs deliver a high specific capacity of 126.6 m Ah/g at0.1 C and long cyclability of 200 cycles at 0.2 C.More importantly,the ASSLBs using moisture-exposed LIC-P can still operate properly by exhibiting a high capacity-retention of 87.7%after 100 cycles under0.2 C.Furthermore,for the first time,we unravel the LIC interfacial morphology evolution upon cycling because the good mechanical durability enables a facile separation of LIC-P from ASSLBs after testing.
基金supported by the Ondokuz Mayis University Project Number PYO.MUH.1901.21.001。
文摘Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity sensing properties of Cu-Mg-Zn ferrites with rare earth element doping were investigated.Single-phase cubic spinel structure was confirmed via X-ray diffraction(XRD),and the crystal size ranges fro m 22.12 to 63.17 nm according to the Scherrer formula and from 25.66 to 67.46 nm according to the Williamson-Hall method.Po rous structure and elemental characterization of the samples were investigated by scanning electron microscopy(SEM).The optic band gap varies between 2.21 and 2.49 eV.Electrical measurements were conducted in the frequency range of 1 Hz-20 MHz and temperature range of 25-400℃.It has been determined that the dielectric results are consistent with the Maxwell-Wagner method and exhibit a non-Debye relaxation model,as observed from the Nyquist plots.At a minimum frequency value of 1 Hz,the dielectric constants for pure,Ce,Sr,and La samples are 9×10^(4),5×10^(4),1×10^(8),and 2×10^(5) at 25℃,and 1.85×10^(8),1.34×10^(8),1.15×10^(10),and 4.4×10^(8)at 400℃.In the same order,for the maximum frequency value of 20 MHz,the dielectric constants at 25℃are 169,166,3799,and 60,while at 400℃they are 734,624,12108,and 774.The La doped sample's low dielectric loss makes it suitable for high-frequency applications.Humidity measurements were performed at room temperature and in the 5%-95%relative humidity range.The humidity properties of the samples were investigated through humidity mapping,sensitivity,hysteresis,and long-term stability tests.Compared to other samples,the results indicate that Ce exhibits better humidity performance with 99%sensitivity and the highest repeatability(91.2%).These results show that Ce-doped ferrite can be used as a low-cost,high-performance humidity sensor.
基金The financial support from Project(Grant Nos.52278432,and 52168066)of National Natural Science Foundation of China and Project(Grant No.K2023G033)of the Science and Technology Research and Development Plan of China National Railway Group Co.,Ltd.were greatly appreciated.
文摘This paper presents a multi-scale experimental investigation of the weathering degradation of red mudstone.Natural rocks were extracted from the surface ground to 120 m,inwhich three sets of samples were selected to consider the different initial rock fabrics.The long-term relative humidity(RH)cycles under two amplitudes were imposed on red mudstone to simulate the weathering process.After RH cycles,a series of uniaxial compression tests,Brazilian splitting tests and bender-extender element tests were carried out to examine the reduction in strength and stiffness.The objective of this study is to develop an extended stress-volume framework characterizing the degradation of natural red mudstone both at microscale and macroscale.Accompanied by the irreversible swelling of the rock specimen is the progressive degradation of strength,stiffness and Poisson's ratio.A unified exponential degradation model in terms of the irreversible volumetric strain was thus proposed to capture such a degradation pattern.The effect of the initial rock fabric was evident.The highest degradation rate and potential were identified in slightly weathered specimens.Significant slaking of aggregates and crack propagation were confirmed by scanning electron microscope(SEM)micrographs,which were considered as the main consequence of structure damage leading to degradation of mechanical properties.The structure damage during RH cycles denoted the hysteresis nature in the response to the cycling hydraulic reaction,in turn causing the increase in volumetric strain.Thus,the stress-volume relation rather than the suction relation was found in more reasonable agreement with the experimental results.
基金supported by the National Natural Science Foundation of China (Nos.21876019 and 22276022)the National Key Research and Development Program of China (No.2019YFC1903903).
文摘Monolithic catalysts with excellent O_(3)catalytic decomposition performance were prepared by in situ loading of Co-doped KMn_(8)O_(16)on the surface of nickel foam.The triple-layer structure with Co-doped KMn_(8)O_(16)/Ni6MnO_(8)/Ni foam was grown spontaneously on the surface of nickel foam by tuning the molar ratio of KMnO_(4)to Co(NO_(3))_(2)·6H_(2)O precursors.Importantly,the formed Ni6MnO_(8)structure between KMn_(8)O_(16)and nickel foam during in situ synthesis process effectively protected nickel foam from further etching,which significantly enhanced the reaction stability of catalyst.The optimum amount of Co doping in KMn_(8)O_(16)was available when the molar ratio of Mn to Co species in the precursor solution was 2:1.And the Mn2Co1 catalyst had abundant oxygen vacancies and excellent hydrophobicity,thus creating outstanding O_(3)decomposition activity.The O_(3)conversion under dry conditions and relative humidity of 65%,90%over a period of 5 hr was 100%,94%and 80%with the space velocity of 28,000 hr^(−1),respectively.The in situ constructed Co-doped KMn_(8)O_(16)/Ni foam catalyst showed the advantages of low price and gradual applicability of the preparation process,which provided an opportunity for the design of monolithic catalyst for O_(3)catalytic decomposition.
文摘As an indispensable part of modern buildings,centralized central air conditioning systems play an important role in maintaining the comfort and air quality of the indoor environment.However,with the increasing energy consumption,how to improve the energy efficiency ratio of air conditioning systems and reduce energy consumption has become an important issue in research and practice.The purpose of this paper is to discuss the impact of humidity control strategies on energy saving in centralized central air conditioning systems,with a view to providing a theoretical basis and practical guidance for realizing building energy efficiency.
基金supported by the National Key R&D Program of China(Nos.2022YFC3700400 and 2022YFC3704000).
文摘The large dynamic range and high performance of temperature and humidity profile lidar made it a popular tool for monitoring the atmospheric environment.In this study,we carried out an accurate analysis of the key components of the lidar system,including lasers,the emitting and receiving light paths,and photodetectors.We combined the validation of simulations with experimental testing,and then the applicability indicators and necessary conditions in accordance were suggested.For the frequency stability of the laser,when the wavelength shift is less than 0.15%,the measurement accuracy of the system can be guaranteed to be less than 5%.The degree of near-field signal distortion will be significantly impacted by the size of the geometric factor’s transition zone.The introduced measurement error is less than 2%when the deviation angle of the emission axis is less than 0.1 mrad.It has been tested that selecting a low-sensitivity detector can help to improve the sensitivity of temperature detection since this channel is sensitive to the detector’s nonlinearity.To enhance lidar’s detection capabilities and direct the lidar system design process,it is beneficial to analyze the precision of the key components.
文摘This paper presents a thermophysical study approach for a pure environmental control system(ECS),incorporating the geometric dimensions of heat exchangers,ram air duct,and air cycle machine(ACM)blades of the Sabreliner’s environmental control system.Real flight scenarios are simulated by considering flight input variables such as altitude,aircraft speed,compression ratio of the air cycle machine,and the mass flow rate of bleed air.The study evaluates the coefficient of performance(COP)of the environmental control system,the heat exchanger efficiencies,and the work distribution of the air cycle machine based on five flight scenarios,with a particular focus on considering the effects of humidity on environmental control system performance.The results demonstrate that at cruising altitude(11,000 m),air humidity conditions allow an increase in the COP of around 9.28%compared to dry conditions.Conversely,on land,humidity conditions reduce the performance by 4.26%compared to dry conditions.It was also found that the effects of humidity at high aircraft speeds become negligible.In general terms,the humidity conditions in the air proved to have positive effects on the environmental control system’s performance but negative effects on the heat exchanger efficiencies,reducing them by 0.22%.Additionally,land conditions reflect significant improvements in performance when the compression ratio of the air cycle machine is varied.Furthermore,in the work distribution of the air cycle machine,humidity conditions were demonstrated to consume 2.91%less work fromthe turbine compared to dry conditions.
基金Under the auspices of the General Project of Science and Technology Department of Shaanxi Province(No.2023-JCYB-264)General Program of National Natural Science Foundation of China(No.41801004,42371008,42471012)。
文摘Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.
