The calculation method about infrared multi-sites passive system location is introduced based on the principle of the weighted least square method, and the variance matrix of estimated error is offered. Through deduct...The calculation method about infrared multi-sites passive system location is introduced based on the principle of the weighted least square method, and the variance matrix of estimated error is offered. Through deduction, it can be found out that treated appraise precision can be directly analyzed and deduced without carrying out real measure and reaching estimation value. The simulation result shows that the system performance based on the weighted least square method is much better than the traditional passive location method, and it can be also used for reference to the research of the location algorithm of similar system.展开更多
The special electronic characteristics and high atom usage efficiency of metal-nitrogen-carbon(M-N-C)materials have made them extremely attractive for oxygen reduction reactions(ORRs).However,it is inevitable that hyd...The special electronic characteristics and high atom usage efficiency of metal-nitrogen-carbon(M-N-C)materials have made them extremely attractive for oxygen reduction reactions(ORRs).However,it is inevitable that hydrogen peroxide(H_(2)O_(2))will be formed via the two-electron pathway in ORRs.Herein,the Cu nanoparticles(NPs)have been encapsulated into Ni doped hollow mesoporous carbon spheres(Ni-HMCS)to reduce the generation of H_(2)O_(2)in ORR.Electrochemical tests confirm that the introduction of Cu NPs improves the ORR performance greatly.The obtained Cu/Ni-HMCS exhibits a half-wave potential of 0.82 V vs.reversible hydrogen electrode and a limited current density of 5.5 mA cm^(-2),which is comparable with the commercial Pt/C.Moreover,Cu/Ni-HMCS has been used in Zn-air battery,demonstrating a high power density of 161 mW cm^(-2)and a long-term recharge capability(50 h at 5 mA cm^(-2)).The theoretical calculation proposes a tandem catalysis pathway for Cu/Ni multi-sites catalysis,that is,H_(2)O_(2)released from the Ni-N_(4)and Cu-N_(4)sites migrates to the Cu(111)face,on which the captive H_(2)O_(2)is further reduced to H_(2)O.This work demonstrates an interesting tandem catalytic pathway of dual-metal multi-sites for ORR,which provides an insight into the development of effective fuel cell electrocatalysts.展开更多
A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multi- site phase-transfer catalyst, α,α',α"-N-hexakis(triethylammoniummethylene chloride)-...A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multi- site phase-transfer catalyst, α,α',α"-N-hexakis(triethylammoniummethylene chloride)-melamine, is developed. A variety of ^-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 2009 Ali Reza Kiasat. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
Accurate multi-step PM_(2.5)(particulate matter with diameters≤2.5 um)concentration prediction is critical for humankinds’health and air populationmanagement because it could provide strong evidence for decisionmaki...Accurate multi-step PM_(2.5)(particulate matter with diameters≤2.5 um)concentration prediction is critical for humankinds’health and air populationmanagement because it could provide strong evidence for decisionmaking.However,it is very challenging due to its randomness and variability.This paper proposed a novel method based on convolutional neural network(CNN)and long-short-term memory(LSTM)with a space-shared mechanism,named space-shared CNN-LSTM(SCNN-LSTM)for multi-site dailyahead multi-step PM_(2.5)forecasting with self-historical series.The proposed SCNN-LSTM contains multi-channel inputs,each channel corresponding to one-site historical PM_(2.5)concentration series.In which,CNN and LSTM are used to extract each site’s rich hidden feature representations in a stack mode.Especially,CNN is to extract the hidden short-time gap PM_(2.5)concentration patterns;LSTM is to mine the hidden features with long-time dependency.Each channel extracted features aremerged as the comprehensive features for future multi-step PM_(2.5)concentration forecasting.Besides,the space-shared mechanism is implemented by multi-loss functions to achieve space information sharing.Therefore,the final features are the fusion of short-time gap,long-time dependency,and space information,which enables forecasting more accurately.To validate the proposed method’s effectiveness,the authors designed,trained,and compared it with various leading methods in terms of RMSE,MAE,MAPE,and R^(2)on four real-word PM_(2.5)data sets in Seoul,South Korea.The massive experiments proved that the proposed method could accurately forecast multi-site multi-step PM_(2.5)concentration only using self-historical PM_(2.5)concentration time series and running once.Specifically,the proposed method obtained averaged RMSE of 8.05,MAE of 5.04,MAPE of 23.96%,and R^(2)of 0.7 for four-site daily ahead 10-hourPM_(2.5)concentration forecasting.展开更多
Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauracea...Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauraceae and to analyse their relationships to current climate and past climate change.Methods:We used ensembles of small models(ESMs)to map the current distributions of 353 Lauraceae species in China and calculated β_(sor) and its β_(sim) and β_(sne) components.We tested the relationship between β_(sor),β_(sne) and β_(sim) with current climate and past climate change related predictors using a series of simultaneous autoregressive(SAR_(err))models.Results:Spatial distribution of β_(sor)of Lauraceae is positively correlated with latitude,showing an inverse rela-tionship to the latitudinalα-diversity(species richness)gradient.High β_(sor) occurs at the boundaries of the warm temperate and subtropical zones and at the Qinghai-Tibet Plateau due to high β_(sne).The optimized SAR_(err) model explainsβ_(sor) andβ_(sne) well,but notβ_(sim).Current mean annual temperature determinesβ_(sor) and β_(sne) of Lauraceae more than anomalies and velocities of temperature or precipitation since the Last Glacial Maximum.Conclusions:Current low temperatures and high climatic heterogeneity are the main factors explaining the high multi-siteβ-diversity of Lauraceae.In contrast to analyses of the β-diversity of entire species assemblages,studies of single plant families can provide complementary insights into the drivers of β-diversity of evolutionarily more narrowly defined entities.展开更多
Cellulose nanofibrils(CNFs)are promising sustainable materials that can be applied to nanocomposites,as well as medical and life-sciences devices.However,methods for the preparation of these important materials are en...Cellulose nanofibrils(CNFs)are promising sustainable materials that can be applied to nanocomposites,as well as medical and life-sciences devices.However,methods for the preparation of these important materials are energy intensive because heating and mechanical disintegration are required to produce cellulose fibers below 100 nm in size.In this study,CNFs were prepared through the multi-site regioselective oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)and periodate at room temperature(20–25°C),without any mechanical-disintegration treatment.Transmission electron microscopy(TEM)revealed that the CNFs had the average widths of 14.1,55.4,and 81.9 nm for three different treatments.Fourier-transform infrared spectroscopy revealed that carboxyl groups were created on the surfaces of the microfibrils,while X-ray diffraction studies showed that the cellulose I structure was maintained after oxidation,and that the cellulose nanofibril crystallinity index exceeded 70%.These results demonstrate that CNFs can be prepared by multi-site regioselective oxidation at room temperature in the absence of mechanical disintegration.In addition,a model was developed to calculate the total content of carboxylate and aldehyde groups of CNFs prepared by the TEMPO mediate oxidation,the periodate oxidation,and the multi-site regioselective oxidation methods based on the particle width determined by TEM.The calculated values of the model were in good agreement with the total content(experimental value)of carboxylate and aldehyde groups of CNFs prepared by the TEMPO-mediated oxidation and the multi-site regioselective oxidation methods.However,the model was not valid for CNFs prepared by the periodate oxidation method.展开更多
With the advent of spinal cord epidural stimulation techniques,i.e.,electrically enabled motor control(e Emc)in combination with activity dependent locomotor training,humans with traumatic complete sensori-motor par...With the advent of spinal cord epidural stimulation techniques,i.e.,electrically enabled motor control(e Emc)in combination with activity dependent locomotor training,humans with traumatic complete sensori-motor paralysis are able to initiate voluntary leg movements and achieve gains in postural control,and bladder and sexual function(Angeli et al.,2014).展开更多
The multi-sited practices (MSP) policy in China is expected to exert found implications upon uneven distribution of high-quality medical resources,coupled with the widespread phenomenon of physician's informal pra...The multi-sited practices (MSP) policy in China is expected to exert found implications upon uneven distribution of high-quality medical resources,coupled with the widespread phenomenon of physician's informal practices on multiple sites.Since 2009,the Chinese government has upheld a policy that allows medical doctors to take on secondary jobs for the purpose of encouraging talented physicians to work in medical institutions and underdeveloped areas where their expertise is badly needed.This paper focuses on the MSP policy in China by examining how it has been implemented at the national and provincial levels through a review of government documents,statistical information,academic papers,and newspaper accounts.Despite the MSP policy is to offer incentive to physicians at first-tier public hospitals to work in primary care centers or areas where their expertise,the evidence is hard to find.This paper identifies several outstanding challenges to the MSP policy:(1) The importance of the MSP policy which is made by the central government is perceived differently at the provincial level by health officials and hospital administrators;(2) Interest in implementing the policy varies among physicians and hospitals;(3) Concerns about quality control and legal responsibilities for medical doctors to take on secondary jobs are widespread.China's MSP policy differs from the 'dual practice' policy in many countries because of its top-down approach,with its emphasis on government's role and administrative intervention.This paper's findings may be useful for other developing countries where medical expertise is unevenly distributed due to market forces.On the special occasion of the Alma Ata Declaration's 40th anniversary and for the sake of promoting Universal Health Coverage,this paper also aims at sharing with other countries China's experience in trying to develop an adequate force of primary care professionals.At the end of this paper,a four-point proposal is made for policy makers in China.展开更多
Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding re...Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding research of families of the species has not been reported previously.Based on diameter at breast height(DBH),height and volume of 25 families on four experimental sites,we calculated variance components,genetic parameters,juvenile and mature trait correlations and made genotype main effect plus genotype×environment interaction effect(GGE)biplot based on the breeding values estimated using the method of best linear unbiased prediction(BLUP).Compared with height,DBH and volume had higher heritability and larger variation coefficients,making them the more suitable traits for family selection and evaluation.Based on these,GGE biplots containing 20 combinations of site×age were drawn using data at 13 to 17 years when the interactions between family and location were strong.Test sites classifications based on DBH,and volume were inconsistent,with two categories for DBH and one for volume.The Guyuan site was the most suitable with strong discriminating ability,high representativeness and stability among tree ages.Integrating the ranking results of DBH and volume,families 66,76,82 and 111 were high-yielding and stable,families 78 and96 were high-yielding with above average stability,families72 and 79 were high-yielding with below average stability,whereas stability of family 100 was inconsistent between DBH and volume.Early selection based on DBH was convenient and reliable,and can be made at seven years.This study provides support for the selection of Larix gmelinii var.principis-rupprechtii families in Hebei province and an example for the application of stem analysis data from multiple sites in tree breeding.展开更多
High and cost-efficient capture of CO_(2) is a prerequisite and an inevitable path of carbon emission reduction. To address the challenges(high cost, low efficiency, less sustainability, etc.) of existing petroleum-ba...High and cost-efficient capture of CO_(2) is a prerequisite and an inevitable path of carbon emission reduction. To address the challenges(high cost, low efficiency, less sustainability, etc.) of existing petroleum-based CO_(2) absorbents, herein, a class of efficient and sustainable lignin-based absorbents were resoundingly prepared by grafting the active amine group on a lignin derived compound vanillin and alkali lignin. The results demonstrated that vanillin modified by acrylamide achieved the excellent absorption capacity among the three absorbents, whose ability was 0.114 g CO_(2) per gram of absorbent under 25 ℃ and 100 kPa. In addition, the absorbent retained stable absorbability of CO_(2) after 6 cycles.The absorbing capacity of the absorbent formed by the coupling of vanillin and acrylamide to CO_(2) was much greater than their own(i.e. 0 g CO_(2) ·g^(-1)vanillin, 0.01 g CO_(2) ·g^(-1) acrylamide, respectively).Detailed information revealed the multi-site synergistic absorption mechanism, in which CO_(2) has C and O double interactions with the amide group of the absorbent, and single interaction with the hydroxyl oxygen on the benzene ring of the absorbent. The absorption capacity of modified lignin for CO_(2) is as high as 0.12 g CO_(2) per gram of absorbent, which is comparable with that of model compound vanillin.This work not only provides a new idea for the design of bio-absorbents for CO_(2) capture, but explores the application potential of lignin-based materials.展开更多
ZnO nanoparticles(nps)among metal oxide(MOs)are proven to be essential electron transporting layers(ETLs)applied in organic solar cells(OSCs).However,intrinsic defects,interfacial charge recombination,and catalytic be...ZnO nanoparticles(nps)among metal oxide(MOs)are proven to be essential electron transporting layers(ETLs)applied in organic solar cells(OSCs).However,intrinsic defects,interfacial charge recombination,and catalytic behavior towards the active layer restrict the applications of ZnO nps for efficient and long-term stable OSCs.The commonly available biomolecule cytidine 5'-monophosphate(CMP-OH)with phosphonic acid,its salt cytidine 5'-monophosphate disodium salt(CMP-ONa)with a phosphate group as an anchoring group and conjugated terminal functional in both analogous molecules provide carrier transfer bridge at bottom interface of the active layer.Systematized theoretical investigations and characterizations have discovered the multi-site coordination of CMP-OH towards acceptor molecules and ZnO nps.The dual-side alignment of CMP analogous molecules hinders interfacial charge recombination and enhances charge transfer potential at once.Inevitably,PM6:L8-BO-based OSCs with modified ETL obtain 18.13%efficiency,12%higher than that of unmodified nps.Besides higher efficiency,CMP-OH-based OSC devices illustrate remarkably improved thermal stability for 500 h at 85℃with 72%of initial PCE and operation stability for 2000 h with 90.1%of initial PCE.This work reveals the passivation mechanism of multi-anchoring groups towards MOs and single-functional groups towards the active layer to optimize the interface for efficient and highly stable OSCs.展开更多
CO_(2) capture is one of the key technologies for dealing with the global warming and implementing lowcarbon development strategy.The emergence of ionic metal-organic frameworks(I-MOFs)has diversified the field of por...CO_(2) capture is one of the key technologies for dealing with the global warming and implementing lowcarbon development strategy.The emergence of ionic metal-organic frameworks(I-MOFs)has diversified the field of porous materials,which have been extensively applied for gas adsorption and separation.In this work,amino-functionalized imidazolium ionic liquid as organic monodentate ligand was used for one step synthesis microporous Cu based I-MOFs.Precise tuning of the adsorption properties was obtained by incorporating aromatic anions,such as phenoxy,benzene carboxyl,and benzene sulfonic acid group into the I-MOFs via a facile ion exchange method.The new I-MOFs showed high thermal stability and high capacity of 5.4 mmol·g^(-1) under atmospheric conditions for selective adsorption of CO_(2).The active sites of microporous Cu-MOF are the ion basic center and unsaturated metal,and electrostatic attraction and hydroxyl bonding between CO_(2) and modified functional sulfonic groups are responsible for the adsorption.This work provides a feasible strategy for the design of I-MOF for functional gas capture.展开更多
Heteroatom-doping of carbocatalysts has been a powerful strategy to remarkably enhance the catalytic performance.Herein,the underlying nature of N promotional effects on peroxymonosulfate(PMS)activation for phenol rem...Heteroatom-doping of carbocatalysts has been a powerful strategy to remarkably enhance the catalytic performance.Herein,the underlying nature of N promotional effects on peroxymonosulfate(PMS)activation for phenol removal is understood by combining kinetics analysis with multiple techniques.A strategy using mixed acid oxidation of carbon nanotube(CNT)followed by NH3 treatment is employed to yield a series of catalysts with different N-doping contents but similar fraction of sp^(2)-hybridized carbon and defective degree,endowing with a chance to discriminate the dominant N-containing active sites.The multi-sites kinetics analysis suggests the graphitic N-containing sites as the dominant active sites.The mechanism of the surface-bound reactive species is also discriminated as the dominant reaction mechanism.The insights reported here could provide the methodology to fundamentally understand the heteroatom-doping effects of carbocatalysis.展开更多
Contamination events in water distribution networks(WDNs)can have a huge impact on water supply and public health;increasingly,online water quality sensors are deployed for real-time detection of contamination events....Contamination events in water distribution networks(WDNs)can have a huge impact on water supply and public health;increasingly,online water quality sensors are deployed for real-time detection of contamination events.Machine learning has been used to integrate multivariate time series water quality data at multiple stations for contamination detection;however,accurate extraction of spatial features in water quality signals remains challenging.This study proposed a contamination detection method based on generative adversarial networks(GANs).The GAN model was constructed to simultaneously consider the spatial correlation between sensor locations and temporal information of water quality indicators.The model consists of two networksda generator and a discriminatordthe outputs of which are used to measure the degree of abnormality of water quality data at each time step,referred to as the anomaly score.Bayesian sequential analysis is used to update the likelihood of event occurrence based on the anomaly scores.Alarms are then generated from the fusion of single-site and multi-site models.The proposed method was tested on a WDN for various contamination events with different characteristics.Results showed high detection performance by the proposed GAN method compared with the minimum volume ellipsoid benchmark method for various contamination amplitudes.Additionally,the GAN method achieved high accuracy for various contamination events with different amplitudes and numbers of anomalous water quality parameters,and water quality data from different sensor stations,highlighting its robustness and potential for practical application to real-time contamination events.展开更多
In recent years,exploration and development of deep shale gas(at a burial depth of 3,500-4,500 m)has become a hotspot in the industry.However,the state of gas storage and transporting mechanism for deep shale gas unde...In recent years,exploration and development of deep shale gas(at a burial depth of 3,500-4,500 m)has become a hotspot in the industry.However,the state of gas storage and transporting mechanism for deep shale gas under high pressure and temperature have not been thoroughly explored,compared with its shallower counterpart.A numerical model for deep shale gas recovery considering multi-site nonisothermal excess adsorption has been established and applied using Finite Element Method.Results from the simulation reveal the following.(1)Excess desorption significantly impacts early-stage performance of deep shale gas well;the conventional way for shallower shale gas development,in which the density of adsorbed gas is not distinguished from that of free gas,overestimates the gas in place(GIP).(2)Although thermal stimulation can speed up the desorption and transporting of deep shale gas,the incremental volume of produced gas,which is impacted not only by seepage velocity but also density of gas,is insignificant,far from expectation.Only an additional 2.03%of cumulative gas would be produced under treatment temperature of 190C and initial reservoir temperature of 90C in a period of 5 years.(3)Matrix porosity,which can be measured on cores in laboratory and/or estimated by using well logging and geophysical data,is the most favorable parameter for deep shale gas recovery.With 60%increase in matrix porosity,an extra 67.25%shale gas on a daily base would be recovered even after 5-year depletion production;(4)Production rate for gas wells in shale reservoirs at 3,500 m and 4,500 m deep would be raised by 5.4%in a 5-year period if the depth of target interval would increase by 340 m without thermal treatment according to the numerical model proposed in the study.展开更多
High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar ...High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar caps-web attachments, more cracks are initiated and grow from the edges of the fastener holes than from features like fillets radii and corners or from large access holes. The main causes of this cracking are the stress concentrations introduced by the fastener holes and by the threaded fasteners themselves, with the most common damage site being at the edge of the fastener holes. Intuitively, it is easy to visualize that after the crack initiation, during the growth stages, some of the load transferred initially by the fastener at the cracked hole will decrease, and it will be shed to the adjacent fasteners that will carry higher loads than in uncracked condition. Using currently available computer software, the method presented in this paper provides a relatively quick and quantitatively defined solution to account for the effects of crack length on the fastener loads transfer, and on the far field and bypass loads at each fastener adjacent to the crack. At each location, these variations are determined from the 3-dimensional distribution of stresses in the joint, and accounting for secondary bending effects and fastener tilt. Two cases of a typical skins lap splice with eight fasteners in a two rows configuration loaded in tension are presented and discussed, one representative for wing or fuselage skins configurations, and the second case representative for cost effective laboratory testing. Each case presents five cracking scenarios, with the cracks growing from approx. 0.03 inch to either the free edge, next hole or both simultaneously.展开更多
基金Supported by the Research Fund for the Department of Science and Technology of Xi'an (No.GG9907)
文摘The calculation method about infrared multi-sites passive system location is introduced based on the principle of the weighted least square method, and the variance matrix of estimated error is offered. Through deduction, it can be found out that treated appraise precision can be directly analyzed and deduced without carrying out real measure and reaching estimation value. The simulation result shows that the system performance based on the weighted least square method is much better than the traditional passive location method, and it can be also used for reference to the research of the location algorithm of similar system.
基金supported by the National Key Research and Development Program of China(2021YFA1501500 and 2018YFA0704502)the National Natural Science Foundation of China(22171265,22201286,22033008 and 22220102005)+2 种基金Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ103)the Open Research Fund of CNMGE Platform&NSCC-TJthe Open Science Promotion Plan 2023 of CSTCloud。
文摘The special electronic characteristics and high atom usage efficiency of metal-nitrogen-carbon(M-N-C)materials have made them extremely attractive for oxygen reduction reactions(ORRs).However,it is inevitable that hydrogen peroxide(H_(2)O_(2))will be formed via the two-electron pathway in ORRs.Herein,the Cu nanoparticles(NPs)have been encapsulated into Ni doped hollow mesoporous carbon spheres(Ni-HMCS)to reduce the generation of H_(2)O_(2)in ORR.Electrochemical tests confirm that the introduction of Cu NPs improves the ORR performance greatly.The obtained Cu/Ni-HMCS exhibits a half-wave potential of 0.82 V vs.reversible hydrogen electrode and a limited current density of 5.5 mA cm^(-2),which is comparable with the commercial Pt/C.Moreover,Cu/Ni-HMCS has been used in Zn-air battery,demonstrating a high power density of 161 mW cm^(-2)and a long-term recharge capability(50 h at 5 mA cm^(-2)).The theoretical calculation proposes a tandem catalysis pathway for Cu/Ni multi-sites catalysis,that is,H_(2)O_(2)released from the Ni-N_(4)and Cu-N_(4)sites migrates to the Cu(111)face,on which the captive H_(2)O_(2)is further reduced to H_(2)O.This work demonstrates an interesting tandem catalytic pathway of dual-metal multi-sites for ORR,which provides an insight into the development of effective fuel cell electrocatalysts.
基金the partial support of this work by Shahid Chamran Research Council
文摘A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multi- site phase-transfer catalyst, α,α',α"-N-hexakis(triethylammoniummethylene chloride)-melamine, is developed. A variety of ^-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 2009 Ali Reza Kiasat. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金This work was supported by a Research Grant from Pukyong National University(2021).
文摘Accurate multi-step PM_(2.5)(particulate matter with diameters≤2.5 um)concentration prediction is critical for humankinds’health and air populationmanagement because it could provide strong evidence for decisionmaking.However,it is very challenging due to its randomness and variability.This paper proposed a novel method based on convolutional neural network(CNN)and long-short-term memory(LSTM)with a space-shared mechanism,named space-shared CNN-LSTM(SCNN-LSTM)for multi-site dailyahead multi-step PM_(2.5)forecasting with self-historical series.The proposed SCNN-LSTM contains multi-channel inputs,each channel corresponding to one-site historical PM_(2.5)concentration series.In which,CNN and LSTM are used to extract each site’s rich hidden feature representations in a stack mode.Especially,CNN is to extract the hidden short-time gap PM_(2.5)concentration patterns;LSTM is to mine the hidden features with long-time dependency.Each channel extracted features aremerged as the comprehensive features for future multi-step PM_(2.5)concentration forecasting.Besides,the space-shared mechanism is implemented by multi-loss functions to achieve space information sharing.Therefore,the final features are the fusion of short-time gap,long-time dependency,and space information,which enables forecasting more accurately.To validate the proposed method’s effectiveness,the authors designed,trained,and compared it with various leading methods in terms of RMSE,MAE,MAPE,and R^(2)on four real-word PM_(2.5)data sets in Seoul,South Korea.The massive experiments proved that the proposed method could accurately forecast multi-site multi-step PM_(2.5)concentration only using self-historical PM_(2.5)concentration time series and running once.Specifically,the proposed method obtained averaged RMSE of 8.05,MAE of 5.04,MAPE of 23.96%,and R^(2)of 0.7 for four-site daily ahead 10-hourPM_(2.5)concentration forecasting.
基金This work was financially supported by the National Key Research and Development Program of China(Grant No.2016YFC0502101)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.SQ2019QZKK1603)a Visiting Scholarship funded by the China Scholarship Council(Grant No.202004910612).
文摘Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauraceae and to analyse their relationships to current climate and past climate change.Methods:We used ensembles of small models(ESMs)to map the current distributions of 353 Lauraceae species in China and calculated β_(sor) and its β_(sim) and β_(sne) components.We tested the relationship between β_(sor),β_(sne) and β_(sim) with current climate and past climate change related predictors using a series of simultaneous autoregressive(SAR_(err))models.Results:Spatial distribution of β_(sor)of Lauraceae is positively correlated with latitude,showing an inverse rela-tionship to the latitudinalα-diversity(species richness)gradient.High β_(sor) occurs at the boundaries of the warm temperate and subtropical zones and at the Qinghai-Tibet Plateau due to high β_(sne).The optimized SAR_(err) model explainsβ_(sor) andβ_(sne) well,but notβ_(sim).Current mean annual temperature determinesβ_(sor) and β_(sne) of Lauraceae more than anomalies and velocities of temperature or precipitation since the Last Glacial Maximum.Conclusions:Current low temperatures and high climatic heterogeneity are the main factors explaining the high multi-siteβ-diversity of Lauraceae.In contrast to analyses of the β-diversity of entire species assemblages,studies of single plant families can provide complementary insights into the drivers of β-diversity of evolutionarily more narrowly defined entities.
基金This research was funded by The Talents Project for Harbin Science and Technology Innovation,grant number 2016RAXXJ006China Postdoctoral Science Foundation,grant number 2017M611341.
文摘Cellulose nanofibrils(CNFs)are promising sustainable materials that can be applied to nanocomposites,as well as medical and life-sciences devices.However,methods for the preparation of these important materials are energy intensive because heating and mechanical disintegration are required to produce cellulose fibers below 100 nm in size.In this study,CNFs were prepared through the multi-site regioselective oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)and periodate at room temperature(20–25°C),without any mechanical-disintegration treatment.Transmission electron microscopy(TEM)revealed that the CNFs had the average widths of 14.1,55.4,and 81.9 nm for three different treatments.Fourier-transform infrared spectroscopy revealed that carboxyl groups were created on the surfaces of the microfibrils,while X-ray diffraction studies showed that the cellulose I structure was maintained after oxidation,and that the cellulose nanofibril crystallinity index exceeded 70%.These results demonstrate that CNFs can be prepared by multi-site regioselective oxidation at room temperature in the absence of mechanical disintegration.In addition,a model was developed to calculate the total content of carboxylate and aldehyde groups of CNFs prepared by the TEMPO mediate oxidation,the periodate oxidation,and the multi-site regioselective oxidation methods based on the particle width determined by TEM.The calculated values of the model were in good agreement with the total content(experimental value)of carboxylate and aldehyde groups of CNFs prepared by the TEMPO-mediated oxidation and the multi-site regioselective oxidation methods.However,the model was not valid for CNFs prepared by the periodate oxidation method.
基金supported by Russian Foundation for Fundamental Research No.16-29-08173-ofi-m(YG)Partial support for data analysis and interpretation of the results was provided from the Russian Science Foundation No.14-45-00024(YG)the Craig H.Neilsen Foundation#72940(PKS)
文摘With the advent of spinal cord epidural stimulation techniques,i.e.,electrically enabled motor control(e Emc)in combination with activity dependent locomotor training,humans with traumatic complete sensori-motor paralysis are able to initiate voluntary leg movements and achieve gains in postural control,and bladder and sexual function(Angeli et al.,2014).
文摘The multi-sited practices (MSP) policy in China is expected to exert found implications upon uneven distribution of high-quality medical resources,coupled with the widespread phenomenon of physician's informal practices on multiple sites.Since 2009,the Chinese government has upheld a policy that allows medical doctors to take on secondary jobs for the purpose of encouraging talented physicians to work in medical institutions and underdeveloped areas where their expertise is badly needed.This paper focuses on the MSP policy in China by examining how it has been implemented at the national and provincial levels through a review of government documents,statistical information,academic papers,and newspaper accounts.Despite the MSP policy is to offer incentive to physicians at first-tier public hospitals to work in primary care centers or areas where their expertise,the evidence is hard to find.This paper identifies several outstanding challenges to the MSP policy:(1) The importance of the MSP policy which is made by the central government is perceived differently at the provincial level by health officials and hospital administrators;(2) Interest in implementing the policy varies among physicians and hospitals;(3) Concerns about quality control and legal responsibilities for medical doctors to take on secondary jobs are widespread.China's MSP policy differs from the 'dual practice' policy in many countries because of its top-down approach,with its emphasis on government's role and administrative intervention.This paper's findings may be useful for other developing countries where medical expertise is unevenly distributed due to market forces.On the special occasion of the Alma Ata Declaration's 40th anniversary and for the sake of promoting Universal Health Coverage,this paper also aims at sharing with other countries China's experience in trying to develop an adequate force of primary care professionals.At the end of this paper,a four-point proposal is made for policy makers in China.
基金supported by the Key Research and Development Program of Hebei Province[20326333D]Science and Technology Promotion Demonstration Project of forestry and grassland in Hebei Province[Hebei TG[2019]001]Science and Technology Promotion Demonstration Project of forestry and grassland in Hebei Province[Hebei TG[2020]013]。
文摘Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding research of families of the species has not been reported previously.Based on diameter at breast height(DBH),height and volume of 25 families on four experimental sites,we calculated variance components,genetic parameters,juvenile and mature trait correlations and made genotype main effect plus genotype×environment interaction effect(GGE)biplot based on the breeding values estimated using the method of best linear unbiased prediction(BLUP).Compared with height,DBH and volume had higher heritability and larger variation coefficients,making them the more suitable traits for family selection and evaluation.Based on these,GGE biplots containing 20 combinations of site×age were drawn using data at 13 to 17 years when the interactions between family and location were strong.Test sites classifications based on DBH,and volume were inconsistent,with two categories for DBH and one for volume.The Guyuan site was the most suitable with strong discriminating ability,high representativeness and stability among tree ages.Integrating the ranking results of DBH and volume,families 66,76,82 and 111 were high-yielding and stable,families 78 and96 were high-yielding with above average stability,families72 and 79 were high-yielding with below average stability,whereas stability of family 100 was inconsistent between DBH and volume.Early selection based on DBH was convenient and reliable,and can be made at seven years.This study provides support for the selection of Larix gmelinii var.principis-rupprechtii families in Hebei province and an example for the application of stem analysis data from multiple sites in tree breeding.
基金supported by National Natural Science Foundation of China (22078023, 22178187)Natural Science Foundation of Shandong Province (ZR202102180830)+1 种基金Taishan Scholars Program of Shandong Province (tsqn201909091)the Startup Foundation of China (3160011181808)。
文摘High and cost-efficient capture of CO_(2) is a prerequisite and an inevitable path of carbon emission reduction. To address the challenges(high cost, low efficiency, less sustainability, etc.) of existing petroleum-based CO_(2) absorbents, herein, a class of efficient and sustainable lignin-based absorbents were resoundingly prepared by grafting the active amine group on a lignin derived compound vanillin and alkali lignin. The results demonstrated that vanillin modified by acrylamide achieved the excellent absorption capacity among the three absorbents, whose ability was 0.114 g CO_(2) per gram of absorbent under 25 ℃ and 100 kPa. In addition, the absorbent retained stable absorbability of CO_(2) after 6 cycles.The absorbing capacity of the absorbent formed by the coupling of vanillin and acrylamide to CO_(2) was much greater than their own(i.e. 0 g CO_(2) ·g^(-1)vanillin, 0.01 g CO_(2) ·g^(-1) acrylamide, respectively).Detailed information revealed the multi-site synergistic absorption mechanism, in which CO_(2) has C and O double interactions with the amide group of the absorbent, and single interaction with the hydroxyl oxygen on the benzene ring of the absorbent. The absorption capacity of modified lignin for CO_(2) is as high as 0.12 g CO_(2) per gram of absorbent, which is comparable with that of model compound vanillin.This work not only provides a new idea for the design of bio-absorbents for CO_(2) capture, but explores the application potential of lignin-based materials.
基金supported by the National Natural Science Foundation of China(22135001)Young Cross Team Project of CAS(No.JCTD-2021-14)+2 种基金Suzhou Science and Technology Program(ST202219)"Dual Carbon"Science and Technology Innovation of Jiangsu Province(Industrial Prospect and Key Technology Research Program)(BE2022021)Vacuum Interconnected Nanotech Workstation,and Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(CAS).
文摘ZnO nanoparticles(nps)among metal oxide(MOs)are proven to be essential electron transporting layers(ETLs)applied in organic solar cells(OSCs).However,intrinsic defects,interfacial charge recombination,and catalytic behavior towards the active layer restrict the applications of ZnO nps for efficient and long-term stable OSCs.The commonly available biomolecule cytidine 5'-monophosphate(CMP-OH)with phosphonic acid,its salt cytidine 5'-monophosphate disodium salt(CMP-ONa)with a phosphate group as an anchoring group and conjugated terminal functional in both analogous molecules provide carrier transfer bridge at bottom interface of the active layer.Systematized theoretical investigations and characterizations have discovered the multi-site coordination of CMP-OH towards acceptor molecules and ZnO nps.The dual-side alignment of CMP analogous molecules hinders interfacial charge recombination and enhances charge transfer potential at once.Inevitably,PM6:L8-BO-based OSCs with modified ETL obtain 18.13%efficiency,12%higher than that of unmodified nps.Besides higher efficiency,CMP-OH-based OSC devices illustrate remarkably improved thermal stability for 500 h at 85℃with 72%of initial PCE and operation stability for 2000 h with 90.1%of initial PCE.This work reveals the passivation mechanism of multi-anchoring groups towards MOs and single-functional groups towards the active layer to optimize the interface for efficient and highly stable OSCs.
基金supported by the National Natural Science Foundation of China(Grant No.22272125)Knowledge Innovation Program of Wuhan-Basic Research(Grant No.2022020801010354)+1 种基金Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(Grant No.2022SX-TD015)Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy(Grant No.YLU-DNL Fund 2021021)。
文摘CO_(2) capture is one of the key technologies for dealing with the global warming and implementing lowcarbon development strategy.The emergence of ionic metal-organic frameworks(I-MOFs)has diversified the field of porous materials,which have been extensively applied for gas adsorption and separation.In this work,amino-functionalized imidazolium ionic liquid as organic monodentate ligand was used for one step synthesis microporous Cu based I-MOFs.Precise tuning of the adsorption properties was obtained by incorporating aromatic anions,such as phenoxy,benzene carboxyl,and benzene sulfonic acid group into the I-MOFs via a facile ion exchange method.The new I-MOFs showed high thermal stability and high capacity of 5.4 mmol·g^(-1) under atmospheric conditions for selective adsorption of CO_(2).The active sites of microporous Cu-MOF are the ion basic center and unsaturated metal,and electrostatic attraction and hydroxyl bonding between CO_(2) and modified functional sulfonic groups are responsible for the adsorption.This work provides a feasible strategy for the design of I-MOF for functional gas capture.
基金supported by the Natural Science Foundation of China(21922803 and 21776077)the Shanghai Natural Science Foundation(17ZR1407300 and 17ZR1407500)+3 种基金the China Postdoctoral Science Foundation(BX20190116)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,the Shanghai Rising-Star Program(17QA1401200)the State Key Laboratory of Organic-Inorganic Composites(oic-201801007)the Open Project of State Key Laboratory of Chemical Engineering(SKLChe-15C03 and SKL-ChE-16C05).
文摘Heteroatom-doping of carbocatalysts has been a powerful strategy to remarkably enhance the catalytic performance.Herein,the underlying nature of N promotional effects on peroxymonosulfate(PMS)activation for phenol removal is understood by combining kinetics analysis with multiple techniques.A strategy using mixed acid oxidation of carbon nanotube(CNT)followed by NH3 treatment is employed to yield a series of catalysts with different N-doping contents but similar fraction of sp^(2)-hybridized carbon and defective degree,endowing with a chance to discriminate the dominant N-containing active sites.The multi-sites kinetics analysis suggests the graphitic N-containing sites as the dominant active sites.The mechanism of the surface-bound reactive species is also discriminated as the dominant reaction mechanism.The insights reported here could provide the methodology to fundamentally understand the heteroatom-doping effects of carbocatalysis.
基金supported by the National Natural Science Foundation of China(52122901,52079016)Fundamental Research Funds for the Central Universities(DUT21GJ203+1 种基金the UK Royal Society(Ref:IF160108 and IEC\NSFC\170249)sponsored by the China Scholarship Council(202106060094).
文摘Contamination events in water distribution networks(WDNs)can have a huge impact on water supply and public health;increasingly,online water quality sensors are deployed for real-time detection of contamination events.Machine learning has been used to integrate multivariate time series water quality data at multiple stations for contamination detection;however,accurate extraction of spatial features in water quality signals remains challenging.This study proposed a contamination detection method based on generative adversarial networks(GANs).The GAN model was constructed to simultaneously consider the spatial correlation between sensor locations and temporal information of water quality indicators.The model consists of two networksda generator and a discriminatordthe outputs of which are used to measure the degree of abnormality of water quality data at each time step,referred to as the anomaly score.Bayesian sequential analysis is used to update the likelihood of event occurrence based on the anomaly scores.Alarms are then generated from the fusion of single-site and multi-site models.The proposed method was tested on a WDN for various contamination events with different characteristics.Results showed high detection performance by the proposed GAN method compared with the minimum volume ellipsoid benchmark method for various contamination amplitudes.Additionally,the GAN method achieved high accuracy for various contamination events with different amplitudes and numbers of anomalous water quality parameters,and water quality data from different sensor stations,highlighting its robustness and potential for practical application to real-time contamination events.
基金support by the program of National Science and Technology Major Project under Grant No.2016ZX05061Sinopec Ministry of Science and Technology Projects(Grant No.P21042-4,P20059-6,P19017-3).
文摘In recent years,exploration and development of deep shale gas(at a burial depth of 3,500-4,500 m)has become a hotspot in the industry.However,the state of gas storage and transporting mechanism for deep shale gas under high pressure and temperature have not been thoroughly explored,compared with its shallower counterpart.A numerical model for deep shale gas recovery considering multi-site nonisothermal excess adsorption has been established and applied using Finite Element Method.Results from the simulation reveal the following.(1)Excess desorption significantly impacts early-stage performance of deep shale gas well;the conventional way for shallower shale gas development,in which the density of adsorbed gas is not distinguished from that of free gas,overestimates the gas in place(GIP).(2)Although thermal stimulation can speed up the desorption and transporting of deep shale gas,the incremental volume of produced gas,which is impacted not only by seepage velocity but also density of gas,is insignificant,far from expectation.Only an additional 2.03%of cumulative gas would be produced under treatment temperature of 190C and initial reservoir temperature of 90C in a period of 5 years.(3)Matrix porosity,which can be measured on cores in laboratory and/or estimated by using well logging and geophysical data,is the most favorable parameter for deep shale gas recovery.With 60%increase in matrix porosity,an extra 67.25%shale gas on a daily base would be recovered even after 5-year depletion production;(4)Production rate for gas wells in shale reservoirs at 3,500 m and 4,500 m deep would be raised by 5.4%in a 5-year period if the depth of target interval would increase by 340 m without thermal treatment according to the numerical model proposed in the study.
文摘High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar caps-web attachments, more cracks are initiated and grow from the edges of the fastener holes than from features like fillets radii and corners or from large access holes. The main causes of this cracking are the stress concentrations introduced by the fastener holes and by the threaded fasteners themselves, with the most common damage site being at the edge of the fastener holes. Intuitively, it is easy to visualize that after the crack initiation, during the growth stages, some of the load transferred initially by the fastener at the cracked hole will decrease, and it will be shed to the adjacent fasteners that will carry higher loads than in uncracked condition. Using currently available computer software, the method presented in this paper provides a relatively quick and quantitatively defined solution to account for the effects of crack length on the fastener loads transfer, and on the far field and bypass loads at each fastener adjacent to the crack. At each location, these variations are determined from the 3-dimensional distribution of stresses in the joint, and accounting for secondary bending effects and fastener tilt. Two cases of a typical skins lap splice with eight fasteners in a two rows configuration loaded in tension are presented and discussed, one representative for wing or fuselage skins configurations, and the second case representative for cost effective laboratory testing. Each case presents five cracking scenarios, with the cracks growing from approx. 0.03 inch to either the free edge, next hole or both simultaneously.