In fulfillment of the national science-and-technology development agenda, the Department of Chemical Sciences of the National Natural Science Foundation of China (NSFC) convened the Strategic Symposium on the Fifteent...In fulfillment of the national science-and-technology development agenda, the Department of Chemical Sciences of the National Natural Science Foundation of China (NSFC) convened the Strategic Symposium on the Fifteenth FiveYear (20262030) Development Plan for Electrochemistry held in Xiamen on 29 August, 2025-the culminating year of the Fourteenth Five-Year (2021-2025) Development Plan. More than forty leading experts in the field of electrochemistry participated with spanning nine thematic fronts: Interfacial Electrocatalysis, Interfacial Electrochemistry for Energy Storage, Bioelectrochemistry, Electrochemistry of Hydrogen Energy, Electrochemical Micro-/Nano-Manufacturing, Operando Electrochemical Characterization, Electro-Thermal Coupling Catalysis, Theoretical and Computational Electrochemistry,and Electrochemical Synthesis. The forum assembled China's foremost electrochemical expertise to blueprint high-quality disciplinary growth for the coming five-year period, thereby serving overarching national strategic needs and sharpening the international competitiveness of Chinese electrochemistry.This paper is presented to highlight the strategic needs and priority areas for the next five years (2026-2030) based on this symposium. The development status of basic research and applied basic research in China's electrochemistry field is systematically reviewed. The in-depth analyses of the existing problems and key challenges in the research and development of electrochemistry related fields are outlined, and the frontier research areas and development trends in the next 5-10 years by integrating national major strategic needs are discussed, which will further promote the academic community to reach a clearer consensus. The proposed strategic roadmap is intended to accelerate a sharpened community consensus, propel the discipline toward high-quality advancement, and furnish a critical reference for building China into a world-leading science and technology power.展开更多
Polymer-derived ceramics(PDCs)pyrolyzed at high temperatures are promising electromagnetic wave(EMW)absorption materials for aerodynamically heated parts of aircraft under harsh environments.Nev-ertheless,high-tempera...Polymer-derived ceramics(PDCs)pyrolyzed at high temperatures are promising electromagnetic wave(EMW)absorption materials for aerodynamically heated parts of aircraft under harsh environments.Nev-ertheless,high-temperature pyrolysis results in a significant increase of electrical and dielectric proper-ties of the ceramics,causing extensive reflection of EMW.To address this challenge,boron nitride-coated carbon nanotubes(BN@CNTs)were fabricated and introduced into polymer-derived SiC(PDC-SiC)by py-rolyzing its precursor higher than 1200℃to form SiC-BN@CNT ceramic composites.The fabricated com-posites with 3 wt.%BN@CNTs pyrolyzed at 1200℃have an effective absorption bandwidth(EAB)of 4.2 GHz(8.2-12.4 GHz)at a thickness of 3.4 mm and the minimum reflection loss(RL min)of-57.20 dB.The ultra-broad EAB of 12.62 GHz(5.38-18 GHz)is obtained by simulation through periodic structure design-ing.The RL of the metamaterials was also measured using an arch testing method at a frequency range of 2-18 GHz and an EAB of 11.52 GHz(6.48-18 GHz)is obtained.The excellent absorption is attributed to the BN layer that limits the electrical conduction of the ceramic composites while retaining the high loss of CNTs.The introduction of BN@CNTs causes the refinement of SiC grains,which provides plenty of interfaces and enhances the interface polarization loss.This work successfully solves the problem that PDCs pyrolyzed at elevated temperatures cannot be used as EMW absorption materials by applying BN coating on CNTs served as absorbers for PDC-SiC.The results of this work greatly broaden the application scope of the PDC systems for EMW absorption.展开更多
Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-or...Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-orthogonal multiple access(NMA) can support more users for m MTC than orthogonal frequency division multiple access(OFDMA). Applying GF transmission in NMA system becomes an active topic recently. The in-depth study on applying GF transmission in pattern division multiple access(PDMA), a competitive candidate scheme of NMA, is investigated in this paper. The definition, latency and allocation of resource and transmission mechanism for GF-PDMA are discussed in detail. The link-level and system-level evaluations are provided to verify the analysis. The analysis and simulation results demonstrate that the proposed GF-PDMA has lower latency than grant based PDMA(GB-PDMA), possesses strong scalability to confront collision and provides almost 2.15 times gain over GF-OFDMA in terms of supporting the number of active users in the system.展开更多
The major challenge faced by the fifth generation(5G) mobile network is higher spectral efficiency and massive connectivity,i.e.,the target spectrum efficiency is 3 times over 4G,and the target connection density is o...The major challenge faced by the fifth generation(5G) mobile network is higher spectral efficiency and massive connectivity,i.e.,the target spectrum efficiency is 3 times over 4G,and the target connection density is one million devices per square kilometer.These requirements are difficult to be satisfied with orthogonal multiple access(OMA) schemes.Non-orthogonal multiple access(NOMA) has thus been proposed as a promising candidate to address some of the challenges for 5G.In this paper,a comprehensive survey of different candidate NOMA schemes for 5G is presented,where the usage scenarios of5 G and the application requirements for NOMA are firstly discussed.A general framework of NOMA scheme is established and the features of typical NOMA schemes are analyzed and compared.We focus on the recent progress and challenge of NOMA in standardization of international telecommunication union(ITU),and 3rd generation partnership project(3GPP).In addition,prototype development and future research directions are also provided respectively.展开更多
Stress, strain and vibration characteristics of rotor parts should be changed significantly under high acceleration, manufacturing error is one of the most important reason. However, current research on this prob- lem...Stress, strain and vibration characteristics of rotor parts should be changed significantly under high acceleration, manufacturing error is one of the most important reason. However, current research on this prob- lem has not been carried out. A rotor with an acceleration of 150,000 g is considered as the objective, the effects of manufacturing errors on rotor mechanical properties and dynamic characteristics are executed by the selection of the key affecting factors. Through the force balance equation of the rotor infinitesimal unit establishment, a theoretical model of stress calculation based on slice method is pro- posed and established, a formula for the rotor stress at any point derives. A finite element model （FEM） of rotor with holes is established with manufacturing errors. The chan- ges of the stresses and strains of a rotor in parallelism and symmetry errors are analyzed, which verify the validity of the theoretical model. The pre-stressing modal analysis is performed based on the aforementioned static analysis. The key dynamic characteristics are analyzed. The results demonstrated that, as the parallelism and symmetry errors increase, the equivalent stresses and strains of the rotor slowly increase linearly, the highest growth rate does not exceed 4%, the maximum change rate of natural frequency is 0.1%. The rotor vibration mode is not significantlyaffected. The FEM construction method of the rotor with manufacturing errors can be utilized for the quantitative research on rotor characteristics, which will assist in the active control of rotor component reliability under high acceleration.展开更多
Pattern division multiple access(PDMA),which is a novel non-orthogonal multiple access(NOMA),has been proposed to address the challenges of massive connectivity and higher spectral efficiency for fifth generation(5G) ...Pattern division multiple access(PDMA),which is a novel non-orthogonal multiple access(NOMA),has been proposed to address the challenges of massive connectivity and higher spectral efficiency for fifth generation(5G) mobile network.The performance of PDMA mainly depends on the design of PDMA pattern matrix.In this paper,pattern matrix design of PDMA for 5G uplink(UL) applications in massive machine type communication(mMTC) and enhanced mobile broadband(eMBB) deployment scenarios are studied.The design criteria and examples for application in UL mMTC and UL eMBB are investigated.The performance of the PDMA pattern matrix is analyzed with the discrete constellation constrained capacity(CC-Capacity),and verified by Monte Carlo simulation.The simulation results show that the preferred PDMA pattern matrix can achieve good performance with different overloading factors(OF).展开更多
OBJECTIVE： This study investigated how polypeptide 2B1 is involved in regulating and governing dampness in rat models with dampness pattern defined in terms of Traditional Chinese Medicine. METHODS： We randomly divi...OBJECTIVE： This study investigated how polypeptide 2B1 is involved in regulating and governing dampness in rat models with dampness pattern defined in terms of Traditional Chinese Medicine. METHODS： We randomly divided 48 SPF 10-week-old male Sprague-Dawley （SD） rats into a normal group, normal ＋ Aristolochic acid I （AA-I） for 5 min group, normal ＋ AA-I for 60 min group, dampness pattern group （DS-Group）, dampness pattern ＋ AA-I for 5 rain tern ＋ AA-I for 60 min group, and dampness pat- group. Groups were then treated accordingly. We took out the lung, stom- ach, liver, spleen, kidney, large intestine, and small intestine tissues to detect gene and protein expres- sion of organic anion transporter polypeptide 2B1 （OATP2B1）. RESULTS= Gene expression of OATP2B1 in spleen, kidney, and small intestine of rats with dampness pattern was lower than that in normal rats （P〈0.05）. The gene expressions of OATP2B1 in liver, stomach, large intestine, and small intestine were lower than that in control rats at different time points after being stimulated by AA-I （P〈0.05）. CONCLUSION There is coordination among multiple viscera in handling the condition of dampness, and the mechanism underlying the action may rely on regulating the expression of OATP2B1.展开更多
Only few glufosinate-tolerant genes,such as phosphinothricin acetyltransferase(PAT)and bialaphos resistance(bar)identified from Streptomyces,are currently available for developing genetically modified rice in agricult...Only few glufosinate-tolerant genes,such as phosphinothricin acetyltransferase(PAT)and bialaphos resistance(bar)identified from Streptomyces,are currently available for developing genetically modified rice in agricultural application.Following the rapid development of genome editing technology,generation of novel glufosinate-tolerant gene resources through artificial evolution of endogenous genes is more promising and highly desirable in rice molecular breeding program.In this study,the endogenous Glutamine synthetase1(OsGS1)was artificially evolved by base-editing-mediated gene evolution(BEMGE)in rice cells to create novel alleles conferring glufosinate tolerance in rice germplasms.Two novel glufosinate-tolerant OsGS1 alleles(OsGS1-AVPS and OsGS1-+AF)and one reported tolerant allele(OsGS1-SGTA)were successfully identified from approximately 4200 independent hygromycin-tolerant calli.Germination assays and spray tests revealed that these three OsGS1 alleles confer glufosinate tolerance in rice.Furthermore,OsGS1-AVPS and OsGS1-SGTA were quickly deployed into the elite rice cultivar Nangeng 46 through precise base editing.Overall,our results demonstrate the feasibility of developing glufosinate-tolerant rice by editing an endogenous rice gene in molecular breeding programs.展开更多
To simultaneously improve the microwave absorption and thermal insulation properties of the ceramic materials for stealth high-speed vehicles,layered composites made of polymer-derived SiOC/ZrB_(2) rein-forced by ZrO_...To simultaneously improve the microwave absorption and thermal insulation properties of the ceramic materials for stealth high-speed vehicles,layered composites made of polymer-derived SiOC/ZrB_(2) rein-forced by ZrO_(2)/SiO_(2) fibers were reported in this work.The composites possess a continuous multilayer structure,which was fabricated via the precursor impregnation assisted by hot press curing and pyrolysis using the transparent ZrO_(2)/SiO_(2) fibers and polymer-derived SiOC and nano ZrB_(2).The layered composites show an effective absorption band(EAB)of 4.2 GHz at a thickness of 2.9 mm and a minimum reflection loss of-59.34 dB.The exceptional electromagnetic(EM)wave attenuation capability is ascribed to the impedance matching as well as massive EM wave loss caused by the multilayers in which the nano ZrB_(2) provides interfacial polarization and electrical conduction loss.With a design of the multi-curvature arch structure,a remarkable reduction of radar cross section can be achieved.Besides,the layered composites exhibit good oxidation resistance and thermal insulation when exposed to the dynamic heating environ-ment,demonstrating the potential application in harsh environments used for multifunctional electro-magnetic absorbing materials.展开更多
The performance and efficiency of a baler deteriorate as a result of gearbox failure.One way to overcome this challenge is to select appropriate fault feature parameters for fault diagnosis and monitoring gearboxes.Th...The performance and efficiency of a baler deteriorate as a result of gearbox failure.One way to overcome this challenge is to select appropriate fault feature parameters for fault diagnosis and monitoring gearboxes.This paper proposes a fault feature selection method using an improved adaptive genetic algorithm for a baler gearbox.This method directly obtains the minimum fault feature parameter set that is most sensitive to fault features through attribute reduction.The main benefit of the improved adaptive genetic algorithm is its excellent performance in terms of the efficiency of attribute reduction without requiring prior information.Therefore,this method should be capable of timely diagnosis and monitoring.Experimental validation was performed and promising findings highlighting the relationship between diagnosis results and faults were obtained.The results indicate that when using the improved genetic algorithm to reduce 12 fault characteristic parameters to three without a priori information,100%fault diagnosis accuracy can be achieved based on these fault characteristics and the time required for fault feature parameter selection using the improved genetic algorithm is reduced by half compared to traditional methods.The proposed method provides important insights into the instant fault diagnosis and fault monitoring of mechanical devices.展开更多
On the request of Prof.Shi-Gang Sun,Editor-in-Chief of Journal of Electrochemistry,I served asthe vip editor for this International Special Issueon Current Electrochemistry.
In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estima...In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling.A DC motor provides assisted power driving,the assistance method is based on the realtime wheel angular velocity and coordinate system transformation.The effect of observer is proved,and the proposed method guarantees stability under disturbances.It is also compared to the existing methods and their performances are illustrated through simulations.The proposed method improves the performance both in rapidity and stability.展开更多
In situ Raman spectroscopic and voltammetric studies indicate that dissociative adsorption of methanol on the rough platinum electrode occurs in the hydrogen ad/desorption potential range, and the dissociative extent ...In situ Raman spectroscopic and voltammetric studies indicate that dissociative adsorption of methanol on the rough platinum electrode occurs in the hydrogen ad/desorption potential range, and the dissociative extent depends on the initial potential of the electrode before contacting methanol, in addition to the contacting time. As the dissociative product, carbon monoxide competes the site of strongly bound hydrogen preferentially, and shifts the ad/desorption potentials of weakly bound hydrogen towards more positive ones gradually with the increase of CO coverage. Whereas, formaldehyde dissociates more easily by far and completely suppresses H-adsorption. The confocal Raman spectroscopy developed on transition metals shows some intriguing advantages in investigating electrocatalytic oxidation of small organic molecules.展开更多
This paper presents an energy resolution study of the JUNO experiment,incorporating the latest knowledge acquired during the detector construction phase.The determination of neutrino mass ordering in JUNO requires an ...This paper presents an energy resolution study of the JUNO experiment,incorporating the latest knowledge acquired during the detector construction phase.The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV.To achieve this ambitious goal,significant efforts have been undertaken in the design and production of the key components of the JUNO detector.Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution,extending beyond the statistical fluctuations of the detected number of photons,such as the properties of the liquid scintillator,performance of photomultiplier tubes,and the energy reconstruction algorithm.To account for these effects,a full JUNO simulation and reconstruction approach is employed.This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution.The results of this study reveal an energy resolution of 2.95% at 1 Mev.Furthermore,this study assesses the contribution of major effects to the overall energy resolution budget.This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data collection.Moreover,it provides a guideline for comprehending the energy resolution characteristics of liquid scintillator-based detectors.展开更多
Carbon fiber reinforced carbon-based composites are considered to be an ideal lightweight material with exceptional high-temperature mechanical performance.Nevertheless,their high conductivity result in a strong refle...Carbon fiber reinforced carbon-based composites are considered to be an ideal lightweight material with exceptional high-temperature mechanical performance.Nevertheless,their high conductivity result in a strong reflection rather than absorption of electromagnetic wave(EMW)for the stealth application.To address this challenge,a novel carbon-based composite made of multi-scale lossy phases(Carbon nanotubes(CNTs),SiC nanowires(SiC_(nws)),and Carbon fiber(C_(f)))and impedance matching phase(SiOC ceramic)was fabricated by the precursor-derived method.The prepared SiC_(nws)/CNTs/C_(f)-C/SiOC(SCC-CS)composites exhibit an effective absorption(EAB)of 2.4 GHz at a thickness of 1.9 mm and a minimum reflection loss(RLmin)of58.44 dB(99%absorption)in the X band.The EMW absorption of the composite is attributed to the multiple loss mechanisms and favorable impedance matching with free space,caused by the multi-conductive phase and SiOC in the composite.In addition,the fabricated composites also have thermal insulation properties and can effectively achieve radar cross-sectional(RCS)reduction,which are promising aerospace composites with the integration of structure and function.展开更多
Power electronics are pivotal components in energy conversion,and their reliability critically influences the long-term operational stability of a system.The power cycling test is one of the most essential tests for r...Power electronics are pivotal components in energy conversion,and their reliability critically influences the long-term operational stability of a system.The power cycling test is one of the most essential tests for reliability research,and lifetime models derived from experimental data or simulations are commonly employed to predict long-term reliability.Numerous lifetime models that reflect a range of test methodologies,operating conditions,failure mechanisms,packaging types,and stress scenarios have been proposed.The adoption of appropriate lifetime models is crucial for the accurate estimation and prediction of the remaining lifetime.In this paper,the foundational principles and build-up process of lifetime models are introduced.Furthermore,the existing lifetime models for power electronics are thoroughly reviewed and categorized from various perspectives,including analytical and physical approaches,traditional wire-bonded versus press-pack insulated gate bipolar transistors(IGBTs),power modules versus discrete devices,elastic versus plastic deformation,low-cycle versus high-cycle fatigue,and uniaxial versus multiaxial stress conditions.The advantages and limitations of each model,along with their respective applicability contexts,are analyzed.Based on this comprehensive review,recommendations are provided for selecting suitable lifetime models for fatigue analysis in power electronics.展开更多
The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment under construction in South China.This paper presents an updated estimate of JUNO’s sensitivity to neutrino mass ordering usin...The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment under construction in South China.This paper presents an updated estimate of JUNO’s sensitivity to neutrino mass ordering using the reactor antineutrinos emitted from eight nuclear reactor cores in the Taishan and Yangjiang nuclear power plants.This measurement is planned by studying the fine interference pattern caused by quasi-vacuum oscillations in the oscillated antineutrino spectrum at a baseline of 52.5 km and is completely independent of the CP violating phase and neutrino mixing angleθ_(23).The sensitivity is obtained through a joint analysis of JUNO and Taishan Antineutrino Observatory(TAO)detectors utilizing the best available knowledge to date about the location and overburden of the JUNO experimental site,local and global nuclear reactors,JUNO and TAO detector responses,expected event rates and spectra of signals and backgrounds,and systematic uncertainties of analysis inputs.We find that a 3σmedian sensitivity to reject the wrong mass ordering hypothesis can be reached with an exposure of about 6.5 years×26.6 GW thermal power.展开更多
文摘In fulfillment of the national science-and-technology development agenda, the Department of Chemical Sciences of the National Natural Science Foundation of China (NSFC) convened the Strategic Symposium on the Fifteenth FiveYear (20262030) Development Plan for Electrochemistry held in Xiamen on 29 August, 2025-the culminating year of the Fourteenth Five-Year (2021-2025) Development Plan. More than forty leading experts in the field of electrochemistry participated with spanning nine thematic fronts: Interfacial Electrocatalysis, Interfacial Electrochemistry for Energy Storage, Bioelectrochemistry, Electrochemistry of Hydrogen Energy, Electrochemical Micro-/Nano-Manufacturing, Operando Electrochemical Characterization, Electro-Thermal Coupling Catalysis, Theoretical and Computational Electrochemistry,and Electrochemical Synthesis. The forum assembled China's foremost electrochemical expertise to blueprint high-quality disciplinary growth for the coming five-year period, thereby serving overarching national strategic needs and sharpening the international competitiveness of Chinese electrochemistry.This paper is presented to highlight the strategic needs and priority areas for the next five years (2026-2030) based on this symposium. The development status of basic research and applied basic research in China's electrochemistry field is systematically reviewed. The in-depth analyses of the existing problems and key challenges in the research and development of electrochemistry related fields are outlined, and the frontier research areas and development trends in the next 5-10 years by integrating national major strategic needs are discussed, which will further promote the academic community to reach a clearer consensus. The proposed strategic roadmap is intended to accelerate a sharpened community consensus, propel the discipline toward high-quality advancement, and furnish a critical reference for building China into a world-leading science and technology power.
基金supported by the National Natural Science Foundation of China(Nos.52232005,52172104,and 52293370)Fundamental Research Funds for the Central Universities(China,Nos.3102020QD0411 and D5000220152)+1 种基金Fundamental Research Funds for the Central Universities(No.3102019TS0409)Cre-ative Research Foundation of Science and Technology on Thermo-Structural Composite Materials Laboratory.
文摘Polymer-derived ceramics(PDCs)pyrolyzed at high temperatures are promising electromagnetic wave(EMW)absorption materials for aerodynamically heated parts of aircraft under harsh environments.Nev-ertheless,high-temperature pyrolysis results in a significant increase of electrical and dielectric proper-ties of the ceramics,causing extensive reflection of EMW.To address this challenge,boron nitride-coated carbon nanotubes(BN@CNTs)were fabricated and introduced into polymer-derived SiC(PDC-SiC)by py-rolyzing its precursor higher than 1200℃to form SiC-BN@CNT ceramic composites.The fabricated com-posites with 3 wt.%BN@CNTs pyrolyzed at 1200℃have an effective absorption bandwidth(EAB)of 4.2 GHz(8.2-12.4 GHz)at a thickness of 3.4 mm and the minimum reflection loss(RL min)of-57.20 dB.The ultra-broad EAB of 12.62 GHz(5.38-18 GHz)is obtained by simulation through periodic structure design-ing.The RL of the metamaterials was also measured using an arch testing method at a frequency range of 2-18 GHz and an EAB of 11.52 GHz(6.48-18 GHz)is obtained.The excellent absorption is attributed to the BN layer that limits the electrical conduction of the ceramic composites while retaining the high loss of CNTs.The introduction of BN@CNTs causes the refinement of SiC grains,which provides plenty of interfaces and enhances the interface polarization loss.This work successfully solves the problem that PDCs pyrolyzed at elevated temperatures cannot be used as EMW absorption materials by applying BN coating on CNTs served as absorbers for PDC-SiC.The results of this work greatly broaden the application scope of the PDC systems for EMW absorption.
基金supported by National High Technology Research and Development Program of China (863 Program, No. 2015AA01A709)
文摘Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-orthogonal multiple access(NMA) can support more users for m MTC than orthogonal frequency division multiple access(OFDMA). Applying GF transmission in NMA system becomes an active topic recently. The in-depth study on applying GF transmission in pattern division multiple access(PDMA), a competitive candidate scheme of NMA, is investigated in this paper. The definition, latency and allocation of resource and transmission mechanism for GF-PDMA are discussed in detail. The link-level and system-level evaluations are provided to verify the analysis. The analysis and simulation results demonstrate that the proposed GF-PDMA has lower latency than grant based PDMA(GB-PDMA), possesses strong scalability to confront collision and provides almost 2.15 times gain over GF-OFDMA in terms of supporting the number of active users in the system.
基金supported by the National High Technology Research and Development Program of China (863 Program, No. 2015AA01A709)
文摘The major challenge faced by the fifth generation(5G) mobile network is higher spectral efficiency and massive connectivity,i.e.,the target spectrum efficiency is 3 times over 4G,and the target connection density is one million devices per square kilometer.These requirements are difficult to be satisfied with orthogonal multiple access(OMA) schemes.Non-orthogonal multiple access(NOMA) has thus been proposed as a promising candidate to address some of the challenges for 5G.In this paper,a comprehensive survey of different candidate NOMA schemes for 5G is presented,where the usage scenarios of5 G and the application requirements for NOMA are firstly discussed.A general framework of NOMA scheme is established and the features of typical NOMA schemes are analyzed and compared.We focus on the recent progress and challenge of NOMA in standardization of international telecommunication union(ITU),and 3rd generation partnership project(3GPP).In addition,prototype development and future research directions are also provided respectively.
基金Supported by National Natural Science Foundation of China(Grant No.51205027)University Youth Fund of Beijing Wuzi University
文摘Stress, strain and vibration characteristics of rotor parts should be changed significantly under high acceleration, manufacturing error is one of the most important reason. However, current research on this prob- lem has not been carried out. A rotor with an acceleration of 150,000 g is considered as the objective, the effects of manufacturing errors on rotor mechanical properties and dynamic characteristics are executed by the selection of the key affecting factors. Through the force balance equation of the rotor infinitesimal unit establishment, a theoretical model of stress calculation based on slice method is pro- posed and established, a formula for the rotor stress at any point derives. A finite element model （FEM） of rotor with holes is established with manufacturing errors. The chan- ges of the stresses and strains of a rotor in parallelism and symmetry errors are analyzed, which verify the validity of the theoretical model. The pre-stressing modal analysis is performed based on the aforementioned static analysis. The key dynamic characteristics are analyzed. The results demonstrated that, as the parallelism and symmetry errors increase, the equivalent stresses and strains of the rotor slowly increase linearly, the highest growth rate does not exceed 4%, the maximum change rate of natural frequency is 0.1%. The rotor vibration mode is not significantlyaffected. The FEM construction method of the rotor with manufacturing errors can be utilized for the quantitative research on rotor characteristics, which will assist in the active control of rotor component reliability under high acceleration.
基金supported by the National High Technology Research and Development Program of China(863 Program,No. 2015AA01A709)
文摘Pattern division multiple access(PDMA),which is a novel non-orthogonal multiple access(NOMA),has been proposed to address the challenges of massive connectivity and higher spectral efficiency for fifth generation(5G) mobile network.The performance of PDMA mainly depends on the design of PDMA pattern matrix.In this paper,pattern matrix design of PDMA for 5G uplink(UL) applications in massive machine type communication(mMTC) and enhanced mobile broadband(eMBB) deployment scenarios are studied.The design criteria and examples for application in UL mMTC and UL eMBB are investigated.The performance of the PDMA pattern matrix is analyzed with the discrete constellation constrained capacity(CC-Capacity),and verified by Monte Carlo simulation.The simulation results show that the preferred PDMA pattern matrix can achieve good performance with different overloading factors(OF).
基金Supported by National Natural Science Foundation of China (Exprimental Study of Relation Between Transit of Dampness Turbidity in Lung,Spleen and Kidney and Adjust and Control of Organic Anion Transportingpolypeptide.No.81072806)
文摘OBJECTIVE： This study investigated how polypeptide 2B1 is involved in regulating and governing dampness in rat models with dampness pattern defined in terms of Traditional Chinese Medicine. METHODS： We randomly divided 48 SPF 10-week-old male Sprague-Dawley （SD） rats into a normal group, normal ＋ Aristolochic acid I （AA-I） for 5 min group, normal ＋ AA-I for 60 min group, dampness pattern group （DS-Group）, dampness pattern ＋ AA-I for 5 rain tern ＋ AA-I for 60 min group, and dampness pat- group. Groups were then treated accordingly. We took out the lung, stom- ach, liver, spleen, kidney, large intestine, and small intestine tissues to detect gene and protein expres- sion of organic anion transporter polypeptide 2B1 （OATP2B1）. RESULTS= Gene expression of OATP2B1 in spleen, kidney, and small intestine of rats with dampness pattern was lower than that in normal rats （P〈0.05）. The gene expressions of OATP2B1 in liver, stomach, large intestine, and small intestine were lower than that in control rats at different time points after being stimulated by AA-I （P〈0.05）. CONCLUSION There is coordination among multiple viscera in handling the condition of dampness, and the mechanism underlying the action may rely on regulating the expression of OATP2B1.
基金supported by grants from the Shenzhen Science and Technology Program(KQTD20180411143628272)Special Funds for Science Technology Innovation and Industrial Development of Shenzhen Dapeng New District(PT202101-02)+3 种基金the Hainan Yazhou Bay Seed Lab(B21HJ0215),the National Natural Science Foundation of China(32102294)the China National Postdoctoral Program for Innovative Talents(BX2020378)the China Postdoctoral Science Foundation(2020M672902)the Central Publicinterest Scientific Institution Basal Research Fund(Y2022PT24).
文摘Only few glufosinate-tolerant genes,such as phosphinothricin acetyltransferase(PAT)and bialaphos resistance(bar)identified from Streptomyces,are currently available for developing genetically modified rice in agricultural application.Following the rapid development of genome editing technology,generation of novel glufosinate-tolerant gene resources through artificial evolution of endogenous genes is more promising and highly desirable in rice molecular breeding program.In this study,the endogenous Glutamine synthetase1(OsGS1)was artificially evolved by base-editing-mediated gene evolution(BEMGE)in rice cells to create novel alleles conferring glufosinate tolerance in rice germplasms.Two novel glufosinate-tolerant OsGS1 alleles(OsGS1-AVPS and OsGS1-+AF)and one reported tolerant allele(OsGS1-SGTA)were successfully identified from approximately 4200 independent hygromycin-tolerant calli.Germination assays and spray tests revealed that these three OsGS1 alleles confer glufosinate tolerance in rice.Furthermore,OsGS1-AVPS and OsGS1-SGTA were quickly deployed into the elite rice cultivar Nangeng 46 through precise base editing.Overall,our results demonstrate the feasibility of developing glufosinate-tolerant rice by editing an endogenous rice gene in molecular breeding programs.
基金supported by the National Natural Science Foun-dation of China(Nos.52232005,52172104,and 52293370)the Fundamental Research Funds for the Central Universities(China,Nos.3102020QD0411 and D5000220152)the Creative Re-search Foundation of Science and Technology on Thermo-Structural Composite Materials Laboratory.
文摘To simultaneously improve the microwave absorption and thermal insulation properties of the ceramic materials for stealth high-speed vehicles,layered composites made of polymer-derived SiOC/ZrB_(2) rein-forced by ZrO_(2)/SiO_(2) fibers were reported in this work.The composites possess a continuous multilayer structure,which was fabricated via the precursor impregnation assisted by hot press curing and pyrolysis using the transparent ZrO_(2)/SiO_(2) fibers and polymer-derived SiOC and nano ZrB_(2).The layered composites show an effective absorption band(EAB)of 4.2 GHz at a thickness of 2.9 mm and a minimum reflection loss of-59.34 dB.The exceptional electromagnetic(EM)wave attenuation capability is ascribed to the impedance matching as well as massive EM wave loss caused by the multilayers in which the nano ZrB_(2) provides interfacial polarization and electrical conduction loss.With a design of the multi-curvature arch structure,a remarkable reduction of radar cross section can be achieved.Besides,the layered composites exhibit good oxidation resistance and thermal insulation when exposed to the dynamic heating environ-ment,demonstrating the potential application in harsh environments used for multifunctional electro-magnetic absorbing materials.
基金National Key R&D Program of China(2016YFd01304)Postgraduate Innovation Support Project of Shijiazhuang Tiedao University(YC20035).
文摘The performance and efficiency of a baler deteriorate as a result of gearbox failure.One way to overcome this challenge is to select appropriate fault feature parameters for fault diagnosis and monitoring gearboxes.This paper proposes a fault feature selection method using an improved adaptive genetic algorithm for a baler gearbox.This method directly obtains the minimum fault feature parameter set that is most sensitive to fault features through attribute reduction.The main benefit of the improved adaptive genetic algorithm is its excellent performance in terms of the efficiency of attribute reduction without requiring prior information.Therefore,this method should be capable of timely diagnosis and monitoring.Experimental validation was performed and promising findings highlighting the relationship between diagnosis results and faults were obtained.The results indicate that when using the improved genetic algorithm to reduce 12 fault characteristic parameters to three without a priori information,100%fault diagnosis accuracy can be achieved based on these fault characteristics and the time required for fault feature parameter selection using the improved genetic algorithm is reduced by half compared to traditional methods.The proposed method provides important insights into the instant fault diagnosis and fault monitoring of mechanical devices.
文摘On the request of Prof.Shi-Gang Sun,Editor-in-Chief of Journal of Electrochemistry,I served asthe vip editor for this International Special Issueon Current Electrochemistry.
基金supported by the National Natural Science Foundation of China(51775325)Hong Kong Scholars Program of China(XJ2013015)。
文摘In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling.A DC motor provides assisted power driving,the assistance method is based on the realtime wheel angular velocity and coordinate system transformation.The effect of observer is proved,and the proposed method guarantees stability under disturbances.It is also compared to the existing methods and their performances are illustrated through simulations.The proposed method improves the performance both in rapidity and stability.
基金Financial support by the National Natural Science Foundation of China (29833060 29903009+2 种基金 20073012) and Visiting Scholar Foundation in State Key Labs of Ministry of Education of China is gratefully acknowledged.
文摘In situ Raman spectroscopic and voltammetric studies indicate that dissociative adsorption of methanol on the rough platinum electrode occurs in the hydrogen ad/desorption potential range, and the dissociative extent depends on the initial potential of the electrode before contacting methanol, in addition to the contacting time. As the dissociative product, carbon monoxide competes the site of strongly bound hydrogen preferentially, and shifts the ad/desorption potentials of weakly bound hydrogen towards more positive ones gradually with the increase of CO coverage. Whereas, formaldehyde dissociates more easily by far and completely suppresses H-adsorption. The confocal Raman spectroscopy developed on transition metals shows some intriguing advantages in investigating electrocatalytic oxidation of small organic molecules.
基金Supported by the Chinese Academy of Sciencesthe National Key R&D Program of China+20 种基金the CAS Center for Excellence in Particle Physics,Wuyi Universitythe Tsung-Dao Lee Institute of Shanghai Jiao Tong University in Chinathe Institut National de Physique Nucléaire et de Physique de Particules(IN2P3)in Francethe Istituto Nazionale di Fisica Nucleare(INFN)in Italythe Italian-Chinese collaborative research program MAECI-NSFCthe Fond de la Recherche Scientifique(F.R.S-FNRS)FWO under the"Excellence of Science-EOS"in Belgiumthe Conselho Nacional de Desenvolvimento Científico e Tecnològico in Brazilthe Agencia Nacional de Investigacion y Desarrollo and ANID Millennium Science Initiative Program—ICN2019_044 in Chilethe Charles University Research Centre and the Ministry of Education,Youth,and Sports in Czech Republicthe Deutsche Forschungsgemeinschaft(DFG)the Helmholtz Associationthe Cluster of Excellence PRISMA+in Germanythe Joint Institute of Nuclear Research(JINR)Lomonosov Moscow State University in Russiathe joint Russian Science Foundation(RSF)National Natural Science Foundation of China(NSFC)research programthe MOST and MOE in Taiwan,Chinathe Chulalongkorn University and Suranaree University of Technology in Thailandthe University of California at Irvinethe National Science Foundation in USA。
文摘This paper presents an energy resolution study of the JUNO experiment,incorporating the latest knowledge acquired during the detector construction phase.The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV.To achieve this ambitious goal,significant efforts have been undertaken in the design and production of the key components of the JUNO detector.Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution,extending beyond the statistical fluctuations of the detected number of photons,such as the properties of the liquid scintillator,performance of photomultiplier tubes,and the energy reconstruction algorithm.To account for these effects,a full JUNO simulation and reconstruction approach is employed.This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution.The results of this study reveal an energy resolution of 2.95% at 1 Mev.Furthermore,this study assesses the contribution of major effects to the overall energy resolution budget.This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data collection.Moreover,it provides a guideline for comprehending the energy resolution characteristics of liquid scintillator-based detectors.
基金supported by the National Natural Science Foundation of China(Nos.52232005,52172104,and 52293370)Aeronautical Science Foundation of China(ASFC),2023Z073053010.
文摘Carbon fiber reinforced carbon-based composites are considered to be an ideal lightweight material with exceptional high-temperature mechanical performance.Nevertheless,their high conductivity result in a strong reflection rather than absorption of electromagnetic wave(EMW)for the stealth application.To address this challenge,a novel carbon-based composite made of multi-scale lossy phases(Carbon nanotubes(CNTs),SiC nanowires(SiC_(nws)),and Carbon fiber(C_(f)))and impedance matching phase(SiOC ceramic)was fabricated by the precursor-derived method.The prepared SiC_(nws)/CNTs/C_(f)-C/SiOC(SCC-CS)composites exhibit an effective absorption(EAB)of 2.4 GHz at a thickness of 1.9 mm and a minimum reflection loss(RLmin)of58.44 dB(99%absorption)in the X band.The EMW absorption of the composite is attributed to the multiple loss mechanisms and favorable impedance matching with free space,caused by the multi-conductive phase and SiOC in the composite.In addition,the fabricated composites also have thermal insulation properties and can effectively achieve radar cross-sectional(RCS)reduction,which are promising aerospace composites with the integration of structure and function.
基金Supported by the State Key Laboratory for Traction and Control System of EMU and Locomotive,China Academy of Railway Sciences Corporation Limited(2023YJ366).
文摘Power electronics are pivotal components in energy conversion,and their reliability critically influences the long-term operational stability of a system.The power cycling test is one of the most essential tests for reliability research,and lifetime models derived from experimental data or simulations are commonly employed to predict long-term reliability.Numerous lifetime models that reflect a range of test methodologies,operating conditions,failure mechanisms,packaging types,and stress scenarios have been proposed.The adoption of appropriate lifetime models is crucial for the accurate estimation and prediction of the remaining lifetime.In this paper,the foundational principles and build-up process of lifetime models are introduced.Furthermore,the existing lifetime models for power electronics are thoroughly reviewed and categorized from various perspectives,including analytical and physical approaches,traditional wire-bonded versus press-pack insulated gate bipolar transistors(IGBTs),power modules versus discrete devices,elastic versus plastic deformation,low-cycle versus high-cycle fatigue,and uniaxial versus multiaxial stress conditions.The advantages and limitations of each model,along with their respective applicability contexts,are analyzed.Based on this comprehensive review,recommendations are provided for selecting suitable lifetime models for fatigue analysis in power electronics.
基金Supported by the Chinese Academy of Sciences,the National Key R&D Program of Chinathe CAS Center for Excellence in Particle Physics,Wuyi University,and the TsungDao Lee Institute of Shanghai Jiao Tong University in China+3 种基金the Institut National de Physique Nucléaire et de Physique de Particules(IN2P3)in Francethe Istituto Nazionale di Fisica Nucleare(INFN)in Italy,the Italian-Chinese collaborative research program MAECI-NSFC,the Fond de la Recherche Scientifique(F.R.S-FNRS)and FWO under the“Excellence of Science–EOS”in Belgium,the Conselho Nacional de Desenvolvimento Cient´ıfico e Tecnol`ogico in Brazil,the Agencia Nacional de Investigacion y Desarrollo and ANID-Millennium Science Initiative Program-ICN2019_044 in Chilethe Charles University Research Centre and the Ministry of Education,Youth,and Sports in Czech Republic,the Deutsche Forschungsgemeinschaft(DFG)the Helmholtz Association,and the Cluster of Excellence PRISMA+in Germany,the Joint Institute of Nuclear Research(JINR)and Lomonosov Moscow State University in Russia,the joint Russian Science Foundation(RSF)and National Natural Science Foundation of China(NSFC)research program,the MOST and MOE in Taiwan,China,the Chulalongkorn University and Suranaree University of Technology in Thailand,University of California at Irvine and the National Science Foundation in the US。
文摘The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment under construction in South China.This paper presents an updated estimate of JUNO’s sensitivity to neutrino mass ordering using the reactor antineutrinos emitted from eight nuclear reactor cores in the Taishan and Yangjiang nuclear power plants.This measurement is planned by studying the fine interference pattern caused by quasi-vacuum oscillations in the oscillated antineutrino spectrum at a baseline of 52.5 km and is completely independent of the CP violating phase and neutrino mixing angleθ_(23).The sensitivity is obtained through a joint analysis of JUNO and Taishan Antineutrino Observatory(TAO)detectors utilizing the best available knowledge to date about the location and overburden of the JUNO experimental site,local and global nuclear reactors,JUNO and TAO detector responses,expected event rates and spectra of signals and backgrounds,and systematic uncertainties of analysis inputs.We find that a 3σmedian sensitivity to reject the wrong mass ordering hypothesis can be reached with an exposure of about 6.5 years×26.6 GW thermal power.
