The research and exploration of manganese-based aqueous zinc-ion batteries have been controversial of cycle stability and mechanism investigation,thus improving the stability and exploring storage mechanism are still ...The research and exploration of manganese-based aqueous zinc-ion batteries have been controversial of cycle stability and mechanism investigation,thus improving the stability and exploring storage mechanism are still the most main issue.Defect engineering has become an effective method to improve cycle stability.Herein,a nitrogen-doped ε-MnO_(2)(MnO_(2)@N)has been prepared using electrochemical deposition and heat treatment under nitrogen atmosphere.As the cathode for zinc-ion batteries,the capacity retention rate of MnO_(2)@N cathode is close to 100%after 500 cycles at 0.5 A g^(-1),while the capacity retention rate for the initial MnO_(2) cathode is 62%.At 5 A g^(-1),the capacity retention rate of MnO_(2)@N cathode is 83%after 1000 cycles,which is much higher than the 27%capacity retention rate for the original MnO_(2) cathode.And it can be found that the oxygen vacancies increase after nitrogen doping,which can improve the conductivity of the MnO_(2)@N cathode.Also,there is Mn-N bond in MnO_(2)@N,which can enhance the electrochemical stability of MnO_(2)@N cathode.In addition,the electrochemical mechanism of MnO_(2)@N cathode has been explored by the CV,GCD and GITT tests.It is found that nitrogen doping promotes the intercalation of H^(+) and the corresponding capacity contribution.Compared with the original MnO_(2) cathode,the diffusion coefficient of H^(+) and Zn^(2+) in MnO_(2)@N cathode increases.Also,the reactions during the charging and discharging process are explored through the ex-situ XRD test.And this work may provide some new ideas for improving the stability of manganese-based zinc-ion batteries.展开更多
The shuttle effect of soluble lithium polysulfides(LiPSs)between electrodes and slow reaction kinetics lead to extreme inefficiency and poor high current cycling stability,which limits the commercial application of Li...The shuttle effect of soluble lithium polysulfides(LiPSs)between electrodes and slow reaction kinetics lead to extreme inefficiency and poor high current cycling stability,which limits the commercial application of Li-S batteries.Herein,the multi-dimensional composite frame has been proposed as the modified separator(MCCoS/PP)of Li-S battery,which is composed of CoS_(2) nanoparticles on alkali-treated MXene nanosheets and carbon nanotubes.Both experiments and theoretical calculations show that bifunctional catalytic activity can be achieved on the MCCoS/PP separator.It can not only promote the liquid-solid conversion in the reduction process,but also accelerate the decomposition of insoluble Li_(2)S in the oxidation process.In addition,LiPSs shuttle effect has been inhibited without a decrease in lithium-ion transference numbers.Simultaneously,the MCCoS/PP separator with good LiPSs adsorption capability arouses redistribution and fixing of active substances,which is also beneficial to the rate performance and cycling stability.The Li-S batteries with the MCCoS/PP separator have a specific capacity of 368.6 mAh g^(−1) at 20C,and the capacity decay per cycle is only 0.033%in 1000 cycles at 7C.Also,high area capacity(6.34 mAh cm^(−2))with a high sulfur loading(7.7 mg cm^(−2))and a low electrolyte/sulfur ratio(7.5μL mg^(−1))is achieved.展开更多
Generally,the so-called expansion agent is very effective in eliminating all the micro-annuli that exist between the casing and the cement sheath or between the cement sheath and the formation.However,this approach ca...Generally,the so-called expansion agent is very effective in eliminating all the micro-annuli that exist between the casing and the cement sheath or between the cement sheath and the formation.However,this approach can detrimentally affect the sealing ability of cement sheath if the expansion agent is used in an unreasonable way.For these reasons,in the present work,numerical simulations have been conducted to analyze the effect of elasticity modulus of cement sheath,the elasticity modulus of formation,the expansion rate of cement,the geo-stress on the micro-annulus caused by cement expansion,and the cement sheath expansion on the integrity of cement sheath and formation.The micro-annulus between the casing and the cement sheath has been found to decrease according to the ratio between the elasticity modulus of formation and the elasticity modulus of cement sheath.A positive correlation has been observed between the micro-annulus and the cement expansion ratio.The microannulus decreases as the geo-stress increases,but the effect of the geo-stress on the micro-annulus is much smaller.In conclusion,the expansion agent is suitable for the formation in which the elasticity modulus is higher than the cement sheath.展开更多
Augmented Reality(AR)is a new mode of interactive media that is becoming increasingly popular.Few universities,however,offer courses specifically in AR.This raises questions on appropriate teaching paradigms for this ...Augmented Reality(AR)is a new mode of interactive media that is becoming increasingly popular.Few universities,however,offer courses specifically in AR.This raises questions on appropriate teaching paradigms for this fast-developing area.This paper,therefore,discusses current challenges for teaching AR including a shortage of teaching staff,segmented teaching materials,and theory-driven assessment methods.As such,we present several strategies currently used in the AR technology and application course at Xiamen University.To improve teaching performance,we introduced part-time tutors who are currently employed within the AR industry.Furthermore,we improved the systematic presentation of our course materials to allow an integrative understanding of them.Students developed AR projects using Huawei,the most popular mobile platform in China.This paper concludes that students who underwent this teaching paradigm developed effective skills and knowledge in AR and successfully advanced their careers.展开更多
Resources,innovation,globalization,and green growth are interconnected pillars that shape societies and economies.By effectively managing resources,fostering innovation,embracing globalization,and embracing green grow...Resources,innovation,globalization,and green growth are interconnected pillars that shape societies and economies.By effectively managing resources,fostering innovation,embracing globalization,and embracing green growth,countries can achieve sustainable development,economic prosperity,and a better future for future generations.In this paper,we examine the nexus of natural resources,innovation,globalization,and green growth in BRICS countries from 1990 to 2021 in light of financial development’s role in promoting green growth.We use dynamic system panel data estimations and robust random effect GLS regression for long-run estimates.BRICS countries experience green growth due to natural resources,globalization,financial development,and research and development.There is a negative relationship between globalization and green growth in the BRICS countries.Policymakers need to consider the policy implications discussed in this document to ensure a greener and more sustainable future for the BRICS countries.To mitigate the negative impacts of globalization on green growth,BRICS countries should enhance their environmental regulations.Stricter standards can help control pollution,promote sustainable resource management,and encourage the adoption of clean technologies.The BRICS countries should prioritize sustainable trade practices by integrating environmental considerations into trade agreements and policies.This could include promoting eco-labeling,supporting eco-friendly supply chains,and reducing trade barriers for environmentally friendly products.展开更多
Since 2020,some new breakthroughs in the field of MXene synthesis scheme such as water-free etching,HCl-based hydrothermal etching,halogen etching,and other novel synthesis methods have been proposed.Not only that,the...Since 2020,some new breakthroughs in the field of MXene synthesis scheme such as water-free etching,HCl-based hydrothermal etching,halogen etching,and other novel synthesis methods have been proposed.Not only that,the application of MXene in zinc-ion storage devices has also made great progress in the past 2 years.The understanding of zinc-ion storage mechanism of MXene has undergone profound changes,and its applications have also become diversified,demonstrating the great potential of MXene for high performance zinc-ion storage devices.In this review,we have summarized the preparation and synthesis of MXene materials and systematically investigated the progress of MXene in aqueous zinc-ion storage devices.In particular,for the synthesis of MXene,we added recent reports of conventional synthesis schemes that have been widely reported to help understand their development and combined with recent novel synthesis schemes to provide a distinct partition framework.In addition,for the application of MXene,we discussed the cognitive change of zinc-ion storage mechanism of MXene and conducted an in-depth discussion about the design philosophy of MXene and their characteristics.Finally,a comprehensive perspective on the future development of MXene in the synthetic strategy and aqueous zinc-ion storage applications have been outlined.展开更多
Nowadays,it is a matter of great concern to design electrode materials with excellent electrochemical performance for supercapacitors by a safe,efficient and simple method.And these characteristics are usually related...Nowadays,it is a matter of great concern to design electrode materials with excellent electrochemical performance for supercapacitors by a safe,efficient and simple method.And these characteristics are usually related to the vacancies and impurities in the electrode.To investigate the effect of the vacancies on the electrochemical properties of the supercapacitor cathode material,the uniform reduced CoNi2S4(r-CoNi2S4)nanosheets with sulfur vacancies have been successfully prepared by a one-step hydrothermal method.And the formation of sulfur vacancies are characterized by Raman,X-ray photoelectron spectroscopy and other means.As the electrode for supercapacitor,the r-CoNi2S4 nanosheet electrode delivers a high capacity of 1918.9 Fg-1 at a current density of 1 A g-1,superior rate capability(87.9%retention at a current density of 20 A g-1)and extraordinary cycling stability.Compared with the original CoNi2S4 nanosheet electrode(1226 F g-1at current density of 1 A g-1),the r-CoNi2S4 nanosheet electrode shows a great improvement.The asymmetric supercapacitor based on the r-CoNi2S4 positive electrode and activated carbon negative electrode exhibits a high energy density of 30.3 Wh kg-1 at a power density of 802.1 W kg-1,as well as excellent long-term cycling stability.The feasibility and great potential of the device in practical applications have been successfully proved by lightening the light emitting diodes of three different colors.展开更多
离子插层已成为提高δ-MnO_(2)作为水系锌离子电池正极材料的循环稳定性和倍率性能的有效策略,但在实践中离子的选择似乎相当随意.本工作选择Cu^(2+)插层δ-MnO_(2),因为Cu^(2+)和Zn^(2+)具有相似的直径,但Cu^(2+)的电负性(1.359)略高于...离子插层已成为提高δ-MnO_(2)作为水系锌离子电池正极材料的循环稳定性和倍率性能的有效策略,但在实践中离子的选择似乎相当随意.本工作选择Cu^(2+)插层δ-MnO_(2),因为Cu^(2+)和Zn^(2+)具有相似的直径,但Cu^(2+)的电负性(1.359)略高于Zn^(2+)(1.347).因此,Cu^(2+)与MnO_(2)晶格具有更强的相互作用,并且在Zn^(2+)和H+的嵌入/脱出循环期间可保持稳定.Cu掺杂的δ-MnO_(2)(CMO)生成了Cu–O键,其电化学性能得到了较大的改善.在2 A g^(-1)的高电流密度下循环600次后,CMO表现出出色的循环稳定性和100%的容量保持率,而原始δ-MnO_(2)的容量保持率仅为23%.当电流密度从0.2增加到2.0 A g^(-1)时,CMO还表现出优异的倍率性能,容量保持率为72%,远高于原始δ-MnO_(2)(32%).由于Cu^(2+)比Zn^(2+)具有更大的电负性,因此Cu–O键作为稳定的“结构之柱”提高了CMO的循环稳定性.Cu^(2+)掺杂还提高了CMO的电子电导率和离子电导率,降低了H+和Zn^(2+)在电极/电解质界面的电荷转移电阻,从而提高了其倍率性能.这项工作为使用插层策略提高电池电化学性能提供了新的见解.展开更多
Automatic modulation classification(AMC)aims to identify the modulation format of the received signals corrupted by the noise,which plays a major role in radio monitoring.In this paper,we propose a novel cascaded conv...Automatic modulation classification(AMC)aims to identify the modulation format of the received signals corrupted by the noise,which plays a major role in radio monitoring.In this paper,we propose a novel cascaded convolutional neural network(CasCNN)-based hierarchical digital modulation classification scheme,where M-ary phase shift keying(PSK)and M-ary quadrature amplitude modulation(QAM)modulation formats are considered to be classified.In CasCNN,two-block convolutional neural networks are cascaded.The first block network is utilized to classify the different classes of modulation formats,namely PSK and QAM.The second block is designed to identify the indexes of the modulations in the same PSK or QAM class.Moreover,it is noted that the gird constellation diagram extracted from the received signal is utilized as the inputs to the CasCNN.Extensive simulations demonstrate that CasCNN yields performance gain and performs stronger robustness to frequency offset compared with other recent methods.Specifically,CasCNN achieves 90%classification accuracy at 4 dB signal-to-noise ratio when the symbol length is set as 256.展开更多
This study described the epidemiologic and clinical characteristics of patients who died from severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection,and pointed out the potential risk factors associated ...This study described the epidemiologic and clinical characteristics of patients who died from severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection,and pointed out the potential risk factors associated with fatal outcomes.Retrospective data from 42 death cases due to SARS-CoV-2 infection at Tongji Hospital Affiliated to Huazhong University of Science and Technology,Wuhan,China was analyzed.Demographics,clinical detection,laboratory findings,and treatments of the deceased were collected and analyzed.The average time between onset of symptoms and admission to the hospitals was 11±5 days of hospitalization.Among the deceased,60%were with co-morbidities.All of them were having fever and bilateral pneumonia on computed tomography,abnormal infection-related biomarkers,and renal impairment.Abnormal blood coagulation parameters that appeared in more than half of them,were consistent with disseminated intravascular coagulation.All of the patients were treated in the ICU.Based on the fact that SARS-CoV-2 infection carries a risk of mortality,we may infer a few older male patients with underlying comorbidities are likely to have the increased risk.Impaired consciousness level,markers of renal impairment and coagulation abnormalities may be poor prognostic factors.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 61376011, 51402141, 61604086, 11975114)the Gansu Provincial Natural Science Foundation of China (No. 17JR5RA198)+1 种基金the Fundamental Research Funds for the Central Universities (No. lzujbky-2018-119, lzujbky-2018-ct08, lzujbky-2019-it23)the Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps (No. 2018AB004).
文摘The research and exploration of manganese-based aqueous zinc-ion batteries have been controversial of cycle stability and mechanism investigation,thus improving the stability and exploring storage mechanism are still the most main issue.Defect engineering has become an effective method to improve cycle stability.Herein,a nitrogen-doped ε-MnO_(2)(MnO_(2)@N)has been prepared using electrochemical deposition and heat treatment under nitrogen atmosphere.As the cathode for zinc-ion batteries,the capacity retention rate of MnO_(2)@N cathode is close to 100%after 500 cycles at 0.5 A g^(-1),while the capacity retention rate for the initial MnO_(2) cathode is 62%.At 5 A g^(-1),the capacity retention rate of MnO_(2)@N cathode is 83%after 1000 cycles,which is much higher than the 27%capacity retention rate for the original MnO_(2) cathode.And it can be found that the oxygen vacancies increase after nitrogen doping,which can improve the conductivity of the MnO_(2)@N cathode.Also,there is Mn-N bond in MnO_(2)@N,which can enhance the electrochemical stability of MnO_(2)@N cathode.In addition,the electrochemical mechanism of MnO_(2)@N cathode has been explored by the CV,GCD and GITT tests.It is found that nitrogen doping promotes the intercalation of H^(+) and the corresponding capacity contribution.Compared with the original MnO_(2) cathode,the diffusion coefficient of H^(+) and Zn^(2+) in MnO_(2)@N cathode increases.Also,the reactions during the charging and discharging process are explored through the ex-situ XRD test.And this work may provide some new ideas for improving the stability of manganese-based zinc-ion batteries.
基金This work was financially supported by the Gansu Provincial Natural Science Foundation of China(Nos.21JR7RA493,17JR5RA198,2020HZ-2,21JR7RA470)the Cooperation project of Gansu Academy of Sciences(2020HZ-2)+3 种基金the Fundamental Research Funds for the Central Universities(Nos.lzujbky-2018-119,lzujbky-2018-ct08,lzujbky-2019-it23)Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps(No.2018AB004)Hubei University of Arts and Science(No.2020kypytd002)Xiangyang Science and Technology Research and Development(No.2020YL09).
文摘The shuttle effect of soluble lithium polysulfides(LiPSs)between electrodes and slow reaction kinetics lead to extreme inefficiency and poor high current cycling stability,which limits the commercial application of Li-S batteries.Herein,the multi-dimensional composite frame has been proposed as the modified separator(MCCoS/PP)of Li-S battery,which is composed of CoS_(2) nanoparticles on alkali-treated MXene nanosheets and carbon nanotubes.Both experiments and theoretical calculations show that bifunctional catalytic activity can be achieved on the MCCoS/PP separator.It can not only promote the liquid-solid conversion in the reduction process,but also accelerate the decomposition of insoluble Li_(2)S in the oxidation process.In addition,LiPSs shuttle effect has been inhibited without a decrease in lithium-ion transference numbers.Simultaneously,the MCCoS/PP separator with good LiPSs adsorption capability arouses redistribution and fixing of active substances,which is also beneficial to the rate performance and cycling stability.The Li-S batteries with the MCCoS/PP separator have a specific capacity of 368.6 mAh g^(−1) at 20C,and the capacity decay per cycle is only 0.033%in 1000 cycles at 7C.Also,high area capacity(6.34 mAh cm^(−2))with a high sulfur loading(7.7 mg cm^(−2))and a low electrolyte/sulfur ratio(7.5μL mg^(−1))is achieved.
基金funded by the Sinopec Science and Technology Department Project(P21056).
文摘Generally,the so-called expansion agent is very effective in eliminating all the micro-annuli that exist between the casing and the cement sheath or between the cement sheath and the formation.However,this approach can detrimentally affect the sealing ability of cement sheath if the expansion agent is used in an unreasonable way.For these reasons,in the present work,numerical simulations have been conducted to analyze the effect of elasticity modulus of cement sheath,the elasticity modulus of formation,the expansion rate of cement,the geo-stress on the micro-annulus caused by cement expansion,and the cement sheath expansion on the integrity of cement sheath and formation.The micro-annulus between the casing and the cement sheath has been found to decrease according to the ratio between the elasticity modulus of formation and the elasticity modulus of cement sheath.A positive correlation has been observed between the micro-annulus and the cement expansion ratio.The microannulus decreases as the geo-stress increases,but the effect of the geo-stress on the micro-annulus is much smaller.In conclusion,the expansion agent is suitable for the formation in which the elasticity modulus is higher than the cement sheath.
文摘Augmented Reality(AR)is a new mode of interactive media that is becoming increasingly popular.Few universities,however,offer courses specifically in AR.This raises questions on appropriate teaching paradigms for this fast-developing area.This paper,therefore,discusses current challenges for teaching AR including a shortage of teaching staff,segmented teaching materials,and theory-driven assessment methods.As such,we present several strategies currently used in the AR technology and application course at Xiamen University.To improve teaching performance,we introduced part-time tutors who are currently employed within the AR industry.Furthermore,we improved the systematic presentation of our course materials to allow an integrative understanding of them.Students developed AR projects using Huawei,the most popular mobile platform in China.This paper concludes that students who underwent this teaching paradigm developed effective skills and knowledge in AR and successfully advanced their careers.
文摘Resources,innovation,globalization,and green growth are interconnected pillars that shape societies and economies.By effectively managing resources,fostering innovation,embracing globalization,and embracing green growth,countries can achieve sustainable development,economic prosperity,and a better future for future generations.In this paper,we examine the nexus of natural resources,innovation,globalization,and green growth in BRICS countries from 1990 to 2021 in light of financial development’s role in promoting green growth.We use dynamic system panel data estimations and robust random effect GLS regression for long-run estimates.BRICS countries experience green growth due to natural resources,globalization,financial development,and research and development.There is a negative relationship between globalization and green growth in the BRICS countries.Policymakers need to consider the policy implications discussed in this document to ensure a greener and more sustainable future for the BRICS countries.To mitigate the negative impacts of globalization on green growth,BRICS countries should enhance their environmental regulations.Stricter standards can help control pollution,promote sustainable resource management,and encourage the adoption of clean technologies.The BRICS countries should prioritize sustainable trade practices by integrating environmental considerations into trade agreements and policies.This could include promoting eco-labeling,supporting eco-friendly supply chains,and reducing trade barriers for environmentally friendly products.
基金Gansu Provincial Natural Science Foundation of China,Grant/Award Numbers:17JR5RA198,2020HZ-2,21JR7RA470Cooperation project of Gansu Academy of Sciences,Grant/Award Number:2020HZ-2+3 种基金Fundamental Research Funds for the Central Universities,Grant/Award Numbers:lzujbky-2018-119,lzujbky-2018-ct08,lzujbky-2019-it23Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps,Grant/Award Number:2018AB004Hubei University of Arts and Science,Grant/Award Number:2020kypytd002Xiangyang Science and Technology Research and Development,Grant/Award Number:2020YL09。
文摘Since 2020,some new breakthroughs in the field of MXene synthesis scheme such as water-free etching,HCl-based hydrothermal etching,halogen etching,and other novel synthesis methods have been proposed.Not only that,the application of MXene in zinc-ion storage devices has also made great progress in the past 2 years.The understanding of zinc-ion storage mechanism of MXene has undergone profound changes,and its applications have also become diversified,demonstrating the great potential of MXene for high performance zinc-ion storage devices.In this review,we have summarized the preparation and synthesis of MXene materials and systematically investigated the progress of MXene in aqueous zinc-ion storage devices.In particular,for the synthesis of MXene,we added recent reports of conventional synthesis schemes that have been widely reported to help understand their development and combined with recent novel synthesis schemes to provide a distinct partition framework.In addition,for the application of MXene,we discussed the cognitive change of zinc-ion storage mechanism of MXene and conducted an in-depth discussion about the design philosophy of MXene and their characteristics.Finally,a comprehensive perspective on the future development of MXene in the synthetic strategy and aqueous zinc-ion storage applications have been outlined.
基金supported by the National Natural Science Foundation of China(61376011 and 51402141)Gansu Provincial Natural Science Foundation(17JR5RA198)+1 种基金the Fundamental Research Funds for the Central Universities(lzujbky-2018-119 and lzujbky-2018-ct08)Shenzhen Science and Technology Innovation Committee(JCYJ20170818155813437)。
文摘Nowadays,it is a matter of great concern to design electrode materials with excellent electrochemical performance for supercapacitors by a safe,efficient and simple method.And these characteristics are usually related to the vacancies and impurities in the electrode.To investigate the effect of the vacancies on the electrochemical properties of the supercapacitor cathode material,the uniform reduced CoNi2S4(r-CoNi2S4)nanosheets with sulfur vacancies have been successfully prepared by a one-step hydrothermal method.And the formation of sulfur vacancies are characterized by Raman,X-ray photoelectron spectroscopy and other means.As the electrode for supercapacitor,the r-CoNi2S4 nanosheet electrode delivers a high capacity of 1918.9 Fg-1 at a current density of 1 A g-1,superior rate capability(87.9%retention at a current density of 20 A g-1)and extraordinary cycling stability.Compared with the original CoNi2S4 nanosheet electrode(1226 F g-1at current density of 1 A g-1),the r-CoNi2S4 nanosheet electrode shows a great improvement.The asymmetric supercapacitor based on the r-CoNi2S4 positive electrode and activated carbon negative electrode exhibits a high energy density of 30.3 Wh kg-1 at a power density of 802.1 W kg-1,as well as excellent long-term cycling stability.The feasibility and great potential of the device in practical applications have been successfully proved by lightening the light emitting diodes of three different colors.
基金supported by Gansu Provincial Natural Science Foundation of China(17JR5RA198 and 21JR7RA470)the Cooperation Project of Gansu Academy of Sciences(2020HZ-2)+3 种基金the Fundamental Research Funds for the Central Universities(lzujbky-2018-119,lzujbky-2018-ct08,and lzujbky-2019-it23)the Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps(2018AB004)Hubei University of Arts and Science(2020kypytd002)Xiangyang Science and Technology Research and Development(2020YL09)。
文摘离子插层已成为提高δ-MnO_(2)作为水系锌离子电池正极材料的循环稳定性和倍率性能的有效策略,但在实践中离子的选择似乎相当随意.本工作选择Cu^(2+)插层δ-MnO_(2),因为Cu^(2+)和Zn^(2+)具有相似的直径,但Cu^(2+)的电负性(1.359)略高于Zn^(2+)(1.347).因此,Cu^(2+)与MnO_(2)晶格具有更强的相互作用,并且在Zn^(2+)和H+的嵌入/脱出循环期间可保持稳定.Cu掺杂的δ-MnO_(2)(CMO)生成了Cu–O键,其电化学性能得到了较大的改善.在2 A g^(-1)的高电流密度下循环600次后,CMO表现出出色的循环稳定性和100%的容量保持率,而原始δ-MnO_(2)的容量保持率仅为23%.当电流密度从0.2增加到2.0 A g^(-1)时,CMO还表现出优异的倍率性能,容量保持率为72%,远高于原始δ-MnO_(2)(32%).由于Cu^(2+)比Zn^(2+)具有更大的电负性,因此Cu–O键作为稳定的“结构之柱”提高了CMO的循环稳定性.Cu^(2+)掺杂还提高了CMO的电子电导率和离子电导率,降低了H+和Zn^(2+)在电极/电解质界面的电荷转移电阻,从而提高了其倍率性能.这项工作为使用插层策略提高电池电化学性能提供了新的见解.
基金National Key Research and Development Program of China under(2019YFB1804404)Beijing Natural Science Foundation(4202046)+1 种基金National Natural Science Foundation of China(61801052)Guangdong Key Field R&D Program(2018B010124001)。
文摘Automatic modulation classification(AMC)aims to identify the modulation format of the received signals corrupted by the noise,which plays a major role in radio monitoring.In this paper,we propose a novel cascaded convolutional neural network(CasCNN)-based hierarchical digital modulation classification scheme,where M-ary phase shift keying(PSK)and M-ary quadrature amplitude modulation(QAM)modulation formats are considered to be classified.In CasCNN,two-block convolutional neural networks are cascaded.The first block network is utilized to classify the different classes of modulation formats,namely PSK and QAM.The second block is designed to identify the indexes of the modulations in the same PSK or QAM class.Moreover,it is noted that the gird constellation diagram extracted from the received signal is utilized as the inputs to the CasCNN.Extensive simulations demonstrate that CasCNN yields performance gain and performs stronger robustness to frequency offset compared with other recent methods.Specifically,CasCNN achieves 90%classification accuracy at 4 dB signal-to-noise ratio when the symbol length is set as 256.
基金supported by grants from the Epidemiology,Early Warning,and Response Techniques of Major Infectious Diseases in the Belt and Road Initiative(#2018ZX10101002)National Natural Science Foundation of China(#81871699)Foundation of Jilin Province Science and Technology Department(#172408GH010234983).
文摘This study described the epidemiologic and clinical characteristics of patients who died from severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection,and pointed out the potential risk factors associated with fatal outcomes.Retrospective data from 42 death cases due to SARS-CoV-2 infection at Tongji Hospital Affiliated to Huazhong University of Science and Technology,Wuhan,China was analyzed.Demographics,clinical detection,laboratory findings,and treatments of the deceased were collected and analyzed.The average time between onset of symptoms and admission to the hospitals was 11±5 days of hospitalization.Among the deceased,60%were with co-morbidities.All of them were having fever and bilateral pneumonia on computed tomography,abnormal infection-related biomarkers,and renal impairment.Abnormal blood coagulation parameters that appeared in more than half of them,were consistent with disseminated intravascular coagulation.All of the patients were treated in the ICU.Based on the fact that SARS-CoV-2 infection carries a risk of mortality,we may infer a few older male patients with underlying comorbidities are likely to have the increased risk.Impaired consciousness level,markers of renal impairment and coagulation abnormalities may be poor prognostic factors.
