Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fu...Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).展开更多
The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded MG.Nevertheless, the conflict between unbalance...The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded MG.Nevertheless, the conflict between unbalanced voltage compensation and negative-sequence reactive power sharing, caused bythe impedance mismatching of distribution lines and distributedgenerators, has not been solved only by Q^(−)-G droop control.In this paper, a distributed cooperative secondary unbalancedvoltage control strategy is proposed to decrease the outputvoltage unbalance factor (VUF) of each droop-controlled DG,as well as to further enhance the negative-sequence reactivepower sharing effectiveness among DGs by properly shiftingup and down the Q^(−)-G droop characteristics of each DG.An algorithm for adaptive VUF weight coefficient is proposedto better suppress VUF under severe imbalance conditions.Furthermore, a negative-sequence small-signal model of an MGunder an unbalanced condition, considering the communicationdelay time of the proposed SUVC, is established to analyze thesystem’s stability and transient performance under the influenceof some critical parameters. Finally, the effectiveness of theproposed strategy is validated by the simulation results froma real-time emulator of StarSim HIL.展开更多
Most of the current object detection algorithms use pretrained models that are trained on ImageNet and then fine-tuned in the network,which can achieve good performance in terms of general object detectors.However,in ...Most of the current object detection algorithms use pretrained models that are trained on ImageNet and then fine-tuned in the network,which can achieve good performance in terms of general object detectors.However,in the field of remote sensing image object detection,as pretrained models are significantly different from remote sensing data,it is meaningful to explore a train-fromscratch technique for remote sensing images.This paper proposes an object detection framework trained from scratch,SRS-Net,and describes the design of a densely connected backbone network to provide integrated hidden layer supervision for the convolution module.Then,two necessary improvement principles are proposed:studying the role of normalization in the network structure,and improving data augmentation methods for remote sensing images.To evaluate the proposed framework,we performed many ablation experiments on the DIOR,DOTA,and AS datasets.The results show that whether using the improved backbone network,the normalization method or training data enhancement strategy,the performance of the object detection network trained from scratch increased.These principles compensate for the lack of pretrained models.Furthermore,we found that SRS-Net could achieve similar to or slightly better performance than baseline methods,and surpassed most advanced general detectors.展开更多
This study demonstrated the impacts of the synthesis methods on the textural structures,chemical properties,and Hg^(0)capture capability of the MnO_(x)system.Compared with the samples synthesized using the precipitati...This study demonstrated the impacts of the synthesis methods on the textural structures,chemical properties,and Hg^(0)capture capability of the MnO_(x)system.Compared with the samples synthesized using the precipitation(PR)and hydrothermal(HT)methods,the adsorbent prepared via the sol-gel(SG)technique gave the best performance.At 150℃,ca.90%Hg^(0)removal efficiency was reached after 7.5 h for MnO_(x)prepared by the SG method,ca.40%higher than that of the other two methods.The specific surface area of the adsorbent synthesized via the SG technique(23 m^(2)/g)was almost double that of the adsorbent prepared by the HT method(12 m^(2)/g)and three times that of the one prepared by the PR method(7 m^(2)/g).The presence of plentiful acid sites from the SG method facilitated the physisorption of Hg^(0),making more Hg^(0)available to be oxidized to HgO by the redox sites and thus giving the adsorbent prepared by the SG method the highest Hg^(0)removal efficiency.The strong oxidative ability accelerated the oxidation of the physically adsorbed Hg^(0)to HgO,which explained the higher Hg^(0)removal efficiency of the sample prepared using the HT method than that of the one synthesized by the PR technique.During the whole Hg^(0)removal cycles,chemisorption dominated,with the initial adsorption stage and the external mass-transfer process playing important roles.展开更多
Object detection in Remote Sensing(RS)has achieved tremendous advances in recent years,but it remains challenging for rotated object detection due to cluttered backgrounds,dense object arrangements and the wide range ...Object detection in Remote Sensing(RS)has achieved tremendous advances in recent years,but it remains challenging for rotated object detection due to cluttered backgrounds,dense object arrangements and the wide range of size variations among objects.To tackle this problem,Dense Context Feature Pyramid Network(DCFPN)and a powerα-Gaussian loss are designed for rotated object detection in this paper.The proposed DCFPN can extract multi-scale information densely and accurately by leveraging a dense multi-path dilation layer to cover all sizes of objects in remote sensing scenarios.For more accurate detection while avoiding bottlenecks such as boundary discontinuity in rotated bounding box regression,a-Gaussian loss,a unified power generalization of existing Gaussian modeling losses is proposed.Furthermore,the properties ofα-Gaussian loss are analyzed comprehensively for a wider range of applications.Experimental results on four datasets(UCAS-AOD,HRSC2016,DIOR-R,and DOTA)show the effectiveness of the proposed method using different detectors,and are superior to the existing methods in both feature extraction and bounding box regression。展开更多
The study addresses the issue of monotonous and lengthy corridors with a single spatial form commonly found in Chinese elderly facilities.We aim to assess the influence of the built spatial environment on the emotions...The study addresses the issue of monotonous and lengthy corridors with a single spatial form commonly found in Chinese elderly facilities.We aim to assess the influence of the built spatial environment on the emotions of the elderly quantitatively.To do this,Virtual Reality(VR)technology was employed to construct a digital twin model featuring three corridor forms:straight,arc,and folded,respectively.Forty participants experienced walking in each corridor form for 144 s,while electroencephalogram(EEG)data and subjective questionnaires were collected to explore the psychological and physiological effects caused by different corridors.The results of the questionnaire indicate that arc corridor yielded the highest satisfaction,followed by straight corridor,and the satisfaction for folded corridor is the lowest.EEG results show that folded corridor has 26.0%higher average power than arc corridor and 6.6%higher than straight corridor.The participants consume less energy and are more satisfied in arc corridor,compared to straight and folded corridors.The results establish a correlation between spatial form and occupant perception,suggesting that moderate spatial variations contribute to a better experience of the elderly.Moreover,this study provides quantitative cross-referencing information to optimize the design methods of public space in elderly facilities.展开更多
In the present work,a novel porous,and chemically stable amine-based covalent organic polymer(POP-1) was designed and synthesized under solvothermal conditions.The porosity,crystallinity,chemical stability,electrochem...In the present work,a novel porous,and chemically stable amine-based covalent organic polymer(POP-1) was designed and synthesized under solvothermal conditions.The porosity,crystallinity,chemical stability,electrochemical properties,and diffuse reflectance of POP-1 were investigated via N_2 sorption experiment,power X-ray diffraction,thermogravimetric analysis,cyclic voltammetry,and ultraviolet visible near infrared spectrometry,respectively.POP-1 exhibits good chemical stability in both acidic and alkaline aqueous solutions,as well as in organic solvents.Undoped POP-1 can be directly used as a photocatalyst for rhodamine B irradiation degradation under light-emitting diode and natural light.The E_a of POP-1 for RhB degradation is 82.37 kJ/mol.Furthermore,POP-1 can be reused as a catalyst in RhB degradation without degraded catalytic activity.展开更多
Elucidating the reaction mechanism of hydrazine oxidation reaction(HzOR)over carbon-based catalysts is highly propitious for the rational design of novel electrocatalysts for HzOR.In present work,isolated first-row tr...Elucidating the reaction mechanism of hydrazine oxidation reaction(HzOR)over carbon-based catalysts is highly propitious for the rational design of novel electrocatalysts for HzOR.In present work,isolated first-row transition metal atoms have been coordinated with N atoms on the graphite layers of carbon nanotubes via a M-N_(4)-C configuration(MSA/CNT,M=Fe,Co and Ni).The HzOR over the three single atom catalysts follows a predominant 4-electron reaction pathway to emit N_(2) and a negligible 1-electron pathway to emit trace of NH3,while their electrocatalytic activity for HzOR is dominated by the absorption energy of N2H4 on them.Furthermore,FeSA/CNT reverses the passivation effect on Fe/C and shows superior performance than CoSA/CNT and NiSA/CNT with a recorded high mass activity for HzOR due to the higher electronic charge of Fe over Co and Ni in the M-N_(4)-C configuration and the lowest absorption energy of N_(2)H_(4) on FeSA/CNT among the three MSA/CNT catalysts.展开更多
The fluid flow in a selective catalytic reduction(SCR)system of a 600 MW power station is optimized using the numerical simulation method in this work.Given that guide plates and straightening gratings are properly in...The fluid flow in a selective catalytic reduction(SCR)system of a 600 MW power station is optimized using the numerical simulation method in this work.Given that guide plates and straightening gratings are properly installed,the relative standard deviation(C_(v))of velocity related to the inlet of an ammonia injection grid(AIG)and catalysts satisfy the engineering demand of<15%,suggesting that a relatively uniform velocity field is obtained.The in-line arrangement of static mixers strengthens the disturbance of fluid,promoting the mixing of reductant NH_(3)with flue gas.The NH_(3)mole fraction C_(v)value correlated to the inlet of catalysts drops to ca.3.5%,which is lower than that in the cases when the mixers are aligned in a staggered style.These results indicate that a solid foundation is achieved for the effective abatement of NO_(x)in practical applications.展开更多
In this study,we prepared Fe_(2)O_(3)-Nb_(2)O_(5)binary mixed oxide catalysts using co-precipitation(CP),sol-gel(SG),and solid process(SR)methods and tested their performance.All the catalysts exhibited over 75%NO_(x)...In this study,we prepared Fe_(2)O_(3)-Nb_(2)O_(5)binary mixed oxide catalysts using co-precipitation(CP),sol-gel(SG),and solid process(SR)methods and tested their performance.All the catalysts exhibited over 75%NO_(x)removal efficiency between 250℃and 400℃.Compared with the samples prepared by the SR method,catalyst synthesized using CP and SG methods possessed a larger specific surface area,which could compensate for the lower surface area-normalized reaction rate originat-ing from the insufficient reactive surface oxygen species,hence exhibiting a relatively high low-temperature apparent deNO_(x)activity.However,at a high-temperature region,limited amount of reactive surface oxygen species,together with abundant strong acid sites,facilitated the proceeding of NH_(3)reduction of NO_(x),which well explained the higher apparent activity of the catalyst prepared by SG method than the other two samples.It seemed that specific surface area had an important role to play in the low-temperature apparent performance of the catalysts,while chemical properties mainly decided the activity at an elevated temperature.展开更多
In this study,a series of Na_(2)S-and S^(0)-decorated ZSM-5 adsorbents were prepared and their Hg^(0) adsorption performance was evaluated.Given that S^(0) and Na_(2)S were co-doped with the mass ratio of S^(0) to ZSM...In this study,a series of Na_(2)S-and S^(0)-decorated ZSM-5 adsorbents were prepared and their Hg^(0) adsorption performance was evaluated.Given that S^(0) and Na_(2)S were co-doped with the mass ratio of S^(0) to ZSM-5 fixed to 2:1,Hg^(0) removal efficiency quadruples compared with raw ZSM-5 and reached ca.100%at 300°C.Combined with the characterization results,it could be concluded that chemical properties,instead of physical structures,played an important role in Hg^(0) removal.Among the various gas components,O_(2),NO,and SO_(2) made negligible impacts on Hg^(0) capture over 2:1-S/ZSM-5 adsorbent surface.After recycling four times,Hg^(0) removal efficiency of 2:1-S/ZSM-5 adsorbent remained higher than 80%,which was indica-tive of a certain recyclability.Finally,XPS results illustrated that S^(0) and S^(2−)on 2:1-S/ZSM-5 surface functioned as the active sites for the transformation of Hg^(0) to HgS,which facilitated the chemisorption process and consequently led to an improved Hg^(0) capture performance.展开更多
Online reviews play a crucial role in the ecosystem of nowadays business(especially e-commerce platforms),and have become the primary source of consumer opinions.To manipulate consumers’opinions,some sellers of e-com...Online reviews play a crucial role in the ecosystem of nowadays business(especially e-commerce platforms),and have become the primary source of consumer opinions.To manipulate consumers’opinions,some sellers of e-commerce platforms outsource opinion spamming with incentives(e.g.,free products)in exchange for incen-tivized reviews.As incentives,by nature,are likely to drive more biased reviews or even fake reviews.Despite e-commerce platforms such as Amazon have taken initiatives to squash the incentivized review practice,sellers turn to various social networking platforms(e.g.,Facebook)to outsource the incentivized reviews.The aggre-gation of sellers who request incentivized reviews and reviewers who seek incentives forms incentivized review groups.In this paper,we focus on the incentivized review groups in e-commerce platforms.We perform the data collections from various social networking platforms,including Facebook,WeChat,and Douban.A measurement study of incentivized review groups is conducted with regards to group members,group activities,and products.To identify the incentivized review groups,we propose a new detection approach based on co-review graphs.Specifically,we employ the community detection method to find the suspicious communities from co-review graphs.We also build a“gold standard”dataset from the data we collected,which contains the information of reviewers who belong to incentivized review groups.We utilize the“gold standard”dataset to evaluate the effectiveness of our detection approach.展开更多
The rising acceptance of e-only policy and open access initiative transforms the collection composition in academic libraries. Accordingly, the roles of electronic, print and open access journals as part of a library...The rising acceptance of e-only policy and open access initiative transforms the collection composition in academic libraries. Accordingly, the roles of electronic, print and open access journals as part of a library’s journal holdings have become different from the past, which needs to be brought to the forefront. Samples of this research are drawn from the articles whose first author is from Wuhan University. They should be issued in 2013 and indexed by SCIE, SSCI or A&HCI. The authors introduced an improved citation checking method to the study by matching the journal cited references of the sample with the journals from print, electronic collections and the world’s major open access databases that are available at the Wuhan University Library in accordance with the publishing year instead of the volume number. Thus, the availability and unavailability of the source journals in open access, electronic, and print journal resources can be examined and compared in a comprehensive manner. By comparing the effectiveness of these three formats of resources as the reference source of published articles, this article attempts to analyze their features and tendencies under the current open access environment as well as discusses how the development of open access journals has impacted the collection building of university libraries in China, so as to provide enlightenment and reference for academic libraries to optimize their resource provision and meet the patrons’ current needs.展开更多
For the significant energy consumption and environmental impact,it is crucial to identify the carbon emission characteristics of building foundations construction during the design phase.This study would like to estab...For the significant energy consumption and environmental impact,it is crucial to identify the carbon emission characteristics of building foundations construction during the design phase.This study would like to establish a process-based carbon evaluating model,by adopting Building Information Modeling(BIM),and calculated the materialization-stage carbon emissions of building foundations without basement space in China,and identifying factors influencing the emissions through correlation analysis.These five factors include the building function type,building structure type,foundation area,foundation treatment method,and foundation depth.Additionally,this study develops several machine learning-based predictive models,including Decision Tree,Random Forest,XGBoost,and Neural Network.Among these models,XGBoost demonstrates a relatively higher degree of accuracy and minimal errors,can achieve the RMSE of 206.62 and R2 of 0.88 based on testing group feedback.The study reveals a substantial variability carbon emissions per building’s floor area of foundations,ranging from 100 to 2000 kgCO_(2)e/m^(2),demonstrating the potential for optimizing carbon emissions during the design phase of buildings.Besides,materials contribute significantly to total carbon emissions,accounting for 78%e97%,suggesting a significant opportunity for using BIM technology in the design phase to optimize carbon reduction efforts.展开更多
基金financialy supported by the National Key R&D Program of China(No.2018YFB1502303)the National Natural Science Foundation of China(No.21722601,U19A2017)China Postdoctoral Science Foundation(No.2019M660389)。
文摘Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).
基金supported by the National Key Research and Development Program of China(2021YFB2601402).
文摘The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded MG.Nevertheless, the conflict between unbalanced voltage compensation and negative-sequence reactive power sharing, caused bythe impedance mismatching of distribution lines and distributedgenerators, has not been solved only by Q^(−)-G droop control.In this paper, a distributed cooperative secondary unbalancedvoltage control strategy is proposed to decrease the outputvoltage unbalance factor (VUF) of each droop-controlled DG,as well as to further enhance the negative-sequence reactivepower sharing effectiveness among DGs by properly shiftingup and down the Q^(−)-G droop characteristics of each DG.An algorithm for adaptive VUF weight coefficient is proposedto better suppress VUF under severe imbalance conditions.Furthermore, a negative-sequence small-signal model of an MGunder an unbalanced condition, considering the communicationdelay time of the proposed SUVC, is established to analyze thesystem’s stability and transient performance under the influenceof some critical parameters. Finally, the effectiveness of theproposed strategy is validated by the simulation results froma real-time emulator of StarSim HIL.
基金supported by the Natural Science Foundation of China(No.61906213).
文摘Most of the current object detection algorithms use pretrained models that are trained on ImageNet and then fine-tuned in the network,which can achieve good performance in terms of general object detectors.However,in the field of remote sensing image object detection,as pretrained models are significantly different from remote sensing data,it is meaningful to explore a train-fromscratch technique for remote sensing images.This paper proposes an object detection framework trained from scratch,SRS-Net,and describes the design of a densely connected backbone network to provide integrated hidden layer supervision for the convolution module.Then,two necessary improvement principles are proposed:studying the role of normalization in the network structure,and improving data augmentation methods for remote sensing images.To evaluate the proposed framework,we performed many ablation experiments on the DIOR,DOTA,and AS datasets.The results show that whether using the improved backbone network,the normalization method or training data enhancement strategy,the performance of the object detection network trained from scratch increased.These principles compensate for the lack of pretrained models.Furthermore,we found that SRS-Net could achieve similar to or slightly better performance than baseline methods,and surpassed most advanced general detectors.
基金This work is supported by the Fundamental Research Funds of China Jiliang University and the Zhejiang Provincial Natural Science Foundation of China(No.LQ22E060003).
文摘This study demonstrated the impacts of the synthesis methods on the textural structures,chemical properties,and Hg^(0)capture capability of the MnO_(x)system.Compared with the samples synthesized using the precipitation(PR)and hydrothermal(HT)methods,the adsorbent prepared via the sol-gel(SG)technique gave the best performance.At 150℃,ca.90%Hg^(0)removal efficiency was reached after 7.5 h for MnO_(x)prepared by the SG method,ca.40%higher than that of the other two methods.The specific surface area of the adsorbent synthesized via the SG technique(23 m^(2)/g)was almost double that of the adsorbent prepared by the HT method(12 m^(2)/g)and three times that of the one prepared by the PR method(7 m^(2)/g).The presence of plentiful acid sites from the SG method facilitated the physisorption of Hg^(0),making more Hg^(0)available to be oxidized to HgO by the redox sites and thus giving the adsorbent prepared by the SG method the highest Hg^(0)removal efficiency.The strong oxidative ability accelerated the oxidation of the physically adsorbed Hg^(0)to HgO,which explained the higher Hg^(0)removal efficiency of the sample prepared using the HT method than that of the one synthesized by the PR technique.During the whole Hg^(0)removal cycles,chemisorption dominated,with the initial adsorption stage and the external mass-transfer process playing important roles.
文摘Object detection in Remote Sensing(RS)has achieved tremendous advances in recent years,but it remains challenging for rotated object detection due to cluttered backgrounds,dense object arrangements and the wide range of size variations among objects.To tackle this problem,Dense Context Feature Pyramid Network(DCFPN)and a powerα-Gaussian loss are designed for rotated object detection in this paper.The proposed DCFPN can extract multi-scale information densely and accurately by leveraging a dense multi-path dilation layer to cover all sizes of objects in remote sensing scenarios.For more accurate detection while avoiding bottlenecks such as boundary discontinuity in rotated bounding box regression,a-Gaussian loss,a unified power generalization of existing Gaussian modeling losses is proposed.Furthermore,the properties ofα-Gaussian loss are analyzed comprehensively for a wider range of applications.Experimental results on four datasets(UCAS-AOD,HRSC2016,DIOR-R,and DOTA)show the effectiveness of the proposed method using different detectors,and are superior to the existing methods in both feature extraction and bounding box regression。
基金This research was funded by General project of Shandong social science planning and research project(Grant No.21CSHJ06)National Natural Science Foundation of China Youth Science Foundation(Grant No.51908301)Shandong Natural Science Foundation Training Fund(Grant No.ZR2019PEE034).
文摘The study addresses the issue of monotonous and lengthy corridors with a single spatial form commonly found in Chinese elderly facilities.We aim to assess the influence of the built spatial environment on the emotions of the elderly quantitatively.To do this,Virtual Reality(VR)technology was employed to construct a digital twin model featuring three corridor forms:straight,arc,and folded,respectively.Forty participants experienced walking in each corridor form for 144 s,while electroencephalogram(EEG)data and subjective questionnaires were collected to explore the psychological and physiological effects caused by different corridors.The results of the questionnaire indicate that arc corridor yielded the highest satisfaction,followed by straight corridor,and the satisfaction for folded corridor is the lowest.EEG results show that folded corridor has 26.0%higher average power than arc corridor and 6.6%higher than straight corridor.The participants consume less energy and are more satisfied in arc corridor,compared to straight and folded corridors.The results establish a correlation between spatial form and occupant perception,suggesting that moderate spatial variations contribute to a better experience of the elderly.Moreover,this study provides quantitative cross-referencing information to optimize the design methods of public space in elderly facilities.
基金supported by the National Natural Science Foundation of China(21601109 and 21403130)the Natural Science Foundation of Shandong Province(ZR2014BQ028)
文摘In the present work,a novel porous,and chemically stable amine-based covalent organic polymer(POP-1) was designed and synthesized under solvothermal conditions.The porosity,crystallinity,chemical stability,electrochemical properties,and diffuse reflectance of POP-1 were investigated via N_2 sorption experiment,power X-ray diffraction,thermogravimetric analysis,cyclic voltammetry,and ultraviolet visible near infrared spectrometry,respectively.POP-1 exhibits good chemical stability in both acidic and alkaline aqueous solutions,as well as in organic solvents.Undoped POP-1 can be directly used as a photocatalyst for rhodamine B irradiation degradation under light-emitting diode and natural light.The E_a of POP-1 for RhB degradation is 82.37 kJ/mol.Furthermore,POP-1 can be reused as a catalyst in RhB degradation without degraded catalytic activity.
基金Project supported by Beijing Natural Science Foundation(No.2194076)the National Natural Science Foundation of China(Nos.21908001,21872003,and U19A2017)the Fundamental Research Funds for the Central Universities。
文摘Elucidating the reaction mechanism of hydrazine oxidation reaction(HzOR)over carbon-based catalysts is highly propitious for the rational design of novel electrocatalysts for HzOR.In present work,isolated first-row transition metal atoms have been coordinated with N atoms on the graphite layers of carbon nanotubes via a M-N_(4)-C configuration(MSA/CNT,M=Fe,Co and Ni).The HzOR over the three single atom catalysts follows a predominant 4-electron reaction pathway to emit N_(2) and a negligible 1-electron pathway to emit trace of NH3,while their electrocatalytic activity for HzOR is dominated by the absorption energy of N2H4 on them.Furthermore,FeSA/CNT reverses the passivation effect on Fe/C and shows superior performance than CoSA/CNT and NiSA/CNT with a recorded high mass activity for HzOR due to the higher electronic charge of Fe over Co and Ni in the M-N_(4)-C configuration and the lowest absorption energy of N_(2)H_(4) on FeSA/CNT among the three MSA/CNT catalysts.
文摘The fluid flow in a selective catalytic reduction(SCR)system of a 600 MW power station is optimized using the numerical simulation method in this work.Given that guide plates and straightening gratings are properly installed,the relative standard deviation(C_(v))of velocity related to the inlet of an ammonia injection grid(AIG)and catalysts satisfy the engineering demand of<15%,suggesting that a relatively uniform velocity field is obtained.The in-line arrangement of static mixers strengthens the disturbance of fluid,promoting the mixing of reductant NH_(3)with flue gas.The NH_(3)mole fraction C_(v)value correlated to the inlet of catalysts drops to ca.3.5%,which is lower than that in the cases when the mixers are aligned in a staggered style.These results indicate that a solid foundation is achieved for the effective abatement of NO_(x)in practical applications.
文摘In this study,we prepared Fe_(2)O_(3)-Nb_(2)O_(5)binary mixed oxide catalysts using co-precipitation(CP),sol-gel(SG),and solid process(SR)methods and tested their performance.All the catalysts exhibited over 75%NO_(x)removal efficiency between 250℃and 400℃.Compared with the samples prepared by the SR method,catalyst synthesized using CP and SG methods possessed a larger specific surface area,which could compensate for the lower surface area-normalized reaction rate originat-ing from the insufficient reactive surface oxygen species,hence exhibiting a relatively high low-temperature apparent deNO_(x)activity.However,at a high-temperature region,limited amount of reactive surface oxygen species,together with abundant strong acid sites,facilitated the proceeding of NH_(3)reduction of NO_(x),which well explained the higher apparent activity of the catalyst prepared by SG method than the other two samples.It seemed that specific surface area had an important role to play in the low-temperature apparent performance of the catalysts,while chemical properties mainly decided the activity at an elevated temperature.
基金This work is supported by the National Natural Science Foundation of China(No.51568024).
文摘In this study,a series of Na_(2)S-and S^(0)-decorated ZSM-5 adsorbents were prepared and their Hg^(0) adsorption performance was evaluated.Given that S^(0) and Na_(2)S were co-doped with the mass ratio of S^(0) to ZSM-5 fixed to 2:1,Hg^(0) removal efficiency quadruples compared with raw ZSM-5 and reached ca.100%at 300°C.Combined with the characterization results,it could be concluded that chemical properties,instead of physical structures,played an important role in Hg^(0) removal.Among the various gas components,O_(2),NO,and SO_(2) made negligible impacts on Hg^(0) capture over 2:1-S/ZSM-5 adsorbent surface.After recycling four times,Hg^(0) removal efficiency of 2:1-S/ZSM-5 adsorbent remained higher than 80%,which was indica-tive of a certain recyclability.Finally,XPS results illustrated that S^(0) and S^(2−)on 2:1-S/ZSM-5 surface functioned as the active sites for the transformation of Hg^(0) to HgS,which facilitated the chemisorption process and consequently led to an improved Hg^(0) capture performance.
文摘Online reviews play a crucial role in the ecosystem of nowadays business(especially e-commerce platforms),and have become the primary source of consumer opinions.To manipulate consumers’opinions,some sellers of e-commerce platforms outsource opinion spamming with incentives(e.g.,free products)in exchange for incen-tivized reviews.As incentives,by nature,are likely to drive more biased reviews or even fake reviews.Despite e-commerce platforms such as Amazon have taken initiatives to squash the incentivized review practice,sellers turn to various social networking platforms(e.g.,Facebook)to outsource the incentivized reviews.The aggre-gation of sellers who request incentivized reviews and reviewers who seek incentives forms incentivized review groups.In this paper,we focus on the incentivized review groups in e-commerce platforms.We perform the data collections from various social networking platforms,including Facebook,WeChat,and Douban.A measurement study of incentivized review groups is conducted with regards to group members,group activities,and products.To identify the incentivized review groups,we propose a new detection approach based on co-review graphs.Specifically,we employ the community detection method to find the suspicious communities from co-review graphs.We also build a“gold standard”dataset from the data we collected,which contains the information of reviewers who belong to incentivized review groups.We utilize the“gold standard”dataset to evaluate the effectiveness of our detection approach.
文摘The rising acceptance of e-only policy and open access initiative transforms the collection composition in academic libraries. Accordingly, the roles of electronic, print and open access journals as part of a library’s journal holdings have become different from the past, which needs to be brought to the forefront. Samples of this research are drawn from the articles whose first author is from Wuhan University. They should be issued in 2013 and indexed by SCIE, SSCI or A&HCI. The authors introduced an improved citation checking method to the study by matching the journal cited references of the sample with the journals from print, electronic collections and the world’s major open access databases that are available at the Wuhan University Library in accordance with the publishing year instead of the volume number. Thus, the availability and unavailability of the source journals in open access, electronic, and print journal resources can be examined and compared in a comprehensive manner. By comparing the effectiveness of these three formats of resources as the reference source of published articles, this article attempts to analyze their features and tendencies under the current open access environment as well as discusses how the development of open access journals has impacted the collection building of university libraries in China, so as to provide enlightenment and reference for academic libraries to optimize their resource provision and meet the patrons’ current needs.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0208600)the Key Research and Development Plan of Shaanxi Province of China(Grant No.2023-ZDLSF-66)+1 种基金the National Natural Science Foundation of China(Grant No.51908111)the SRTP project of Southeast University(Grant No.202310286006Z).
文摘For the significant energy consumption and environmental impact,it is crucial to identify the carbon emission characteristics of building foundations construction during the design phase.This study would like to establish a process-based carbon evaluating model,by adopting Building Information Modeling(BIM),and calculated the materialization-stage carbon emissions of building foundations without basement space in China,and identifying factors influencing the emissions through correlation analysis.These five factors include the building function type,building structure type,foundation area,foundation treatment method,and foundation depth.Additionally,this study develops several machine learning-based predictive models,including Decision Tree,Random Forest,XGBoost,and Neural Network.Among these models,XGBoost demonstrates a relatively higher degree of accuracy and minimal errors,can achieve the RMSE of 206.62 and R2 of 0.88 based on testing group feedback.The study reveals a substantial variability carbon emissions per building’s floor area of foundations,ranging from 100 to 2000 kgCO_(2)e/m^(2),demonstrating the potential for optimizing carbon emissions during the design phase of buildings.Besides,materials contribute significantly to total carbon emissions,accounting for 78%e97%,suggesting a significant opportunity for using BIM technology in the design phase to optimize carbon reduction efforts.