Metal-organic frameworks recently have been burgeoning and used as precursors to obtain various metal-nitrogen-carbon catalysts for oxygen reduction reaction(ORR).Although rarely studied,Mn-N-C is a promising catalyst...Metal-organic frameworks recently have been burgeoning and used as precursors to obtain various metal-nitrogen-carbon catalysts for oxygen reduction reaction(ORR).Although rarely studied,Mn-N-C is a promising catalyst for ORR due to its weak Fenton reaction activity and strong graphitization catalysis.Here,we developed a facile strategy for anchoring the atomically dispersed nitrogen-coordinated single Mn sites on carbon nanosheets(MnNCS)from an Mn-hexamine coordination framework.The atomically dispersed Mn-N_(4) sites were dispersed on ultrathin carbon nanosheets with a hierarchically porous structure.The optimized MnNCS displayed an excellent ORR performance in half-cells(0.89 V vs.reversible hydrogen electrode(RHE)in base and 0.76 V vs.RHE in acid in half-wave potential)and Zn-air batteries(233 mW cm^(−2)in peak power density),along with significantly enhanced stability.Density functional theory calculations further corroborated that the Mn-N_(4)-C(12)site has favorable adsorption of*OH as the rate-determining step.These findings demonstrate that the metal-hexamine coordination framework can be used as a model system for the rational design of highly active atomic metal catalysts for energy applications.展开更多
Objective: The purpose of this study was to evaluate the difference in alcohol use between urban and rural students of Inner Mongolia Medical University. Methods: A cross-sectional census was conducted on medical stud...Objective: The purpose of this study was to evaluate the difference in alcohol use between urban and rural students of Inner Mongolia Medical University. Methods: A cross-sectional census was conducted on medical students on campus in 2013. We use multivariate logistic regression models to assess the factors associated with alcohol use. We further use chi-square test assess on differences in alcohol use between urban and rural people among significance factors in logistic regression models. Results: The prevalence of alcohol use among students in rural area was higher than that in urban area (p = 0.016). Alcohol use was associated with Gender, monthly expenses, residence, ethnic and faculty. The odds of alcohol use for Mongolia students were 1.139 times higher than that for Han students. The prevalence of alcohol consumption among students from pharmacy or Traditional Chinese Medicine and Mongolian Medicine faculties in rural area was higher than that among student in urban area (p = 0.03;p = 0.001). The prevalence of alcohol use among female students in rural area was higher than that among female students in urban area (p < 0.043). The proportion of alcohol use among students with <600 in rural area was higher than that among students in urban area (p < 0.001). Conclusion: Considering the differences in the prevalence of alcohol use between rural area and urban area, university administrators aiming at students from various regions develop various approaches.展开更多
Heterogeneous network(HetNet) as a promising technology to improve spectrum efficiency and system capacity has been concerned by many scholars, which brings huge challenges for power allocation and interference manage...Heterogeneous network(HetNet) as a promising technology to improve spectrum efficiency and system capacity has been concerned by many scholars, which brings huge challenges for power allocation and interference management in multicell network structures. Although some works have been done for power allocation in heterogeneous femtocell networks, most of them focus centralized schemes for single-cell network under interference constraint of macrocell user. In this paper, a sum-rate maximization based power allocation algorithm is proposed for a downlink cognitive Het Net with one macrocell network and multiple microcell networks. The original power allocation optimization problem with the consideration of cross-tier interference constraint, maximum transmit power constraint of microcell base station and inter-cell interference of microcell networks is converted into a geometric programming problem which can be solved by Lagrange dual method in a distributed way. Simulation results demonstrate the performance and effectiveness of the proposed algorithm by comparing with the equal power allocation scheme.展开更多
Mutual synchronization is a ubiquitous phenomenon that exists in various natural systems. The individual participants in this process can be modeled as oscillators, which interact by discrete pulses. In this paper, we...Mutual synchronization is a ubiquitous phenomenon that exists in various natural systems. The individual participants in this process can be modeled as oscillators, which interact by discrete pulses. In this paper, we analyze the synchronization condition of two- and multi-oscillators system, and propose a linear pulse-coupled oscillators model. We prove that the proposed model can achieve synchronization for almost all conditions. Numerical simulations are also included to investigate how different model parameters affect the synchronization. We also discuss the implementation of the model as a new approach for time synchronization in wireless sensor networks.展开更多
The Multiple-Input Multiple-Output(MIMO)Non-Orthogonal Multiple Access(NOMA)based on Spatial Modulation(SM-MIMO-NOMA)system has been proposed to achieve better spectral efficiency with reduced radio frequency chains c...The Multiple-Input Multiple-Output(MIMO)Non-Orthogonal Multiple Access(NOMA)based on Spatial Modulation(SM-MIMO-NOMA)system has been proposed to achieve better spectral efficiency with reduced radio frequency chains comparing to the traditional MIMO-NOMA system.To improve the performance of SM-MIMO-NOMA systems,we extend them to generalized spatial modulation scenarios while maintaining moderate complexity and fairness.In this paper,system spectral efficiency and transmission quality improvements are proposed by investigating a sum-rate maximization resource allocation problem that is subject to the total transmitted power,user grouping,and resource block constraints.To solve this non-convex and difficult problem,a graph-based user grouping strategy is proposed initially to maximize the mutual gains of intragroup users.An auxiliary-variable approach is then adopted to transform the power allocation subproblem into a convex one.Simulation results demonstrate that the proposed algorithm has better performance in terms of bit error rate and sum rates.展开更多
Osteoinductive properties of β-TCP remain unknown in humans. It is important to improve the bone grafts which have been the standard treatment for bone defect due to their biocompatibility and bone-healing properties...Osteoinductive properties of β-TCP remain unknown in humans. It is important to improve the bone grafts which have been the standard treatment for bone defect due to their biocompatibility and bone-healing properties. The purpose of this study was to radiologically clarify the bone forming property of β-TCP by evaluating the replacement of β-TCP by newly formed bone in the defect after fibular resection and to examine the histological features of a β-TCP specimen three months after grafting. Radiographs of 17 patients who underwent β-TCP grafting were evaluated. Osteoinductive and osteoconductive properties were assessed by examining bone formation from the remnant fibula, periosteum, and β-TCP alone. In one case, β-TCP was removed later because of postoperative complications and was evaluated histologically. Twenty two of 34 sites between the remnant fibula and β-TCP had achieved good bone regeneration. Five of 14 sites between the periosteum and β-TCP had achieved good bone regeneration. We found immature but evident bone formation in three cases with no osseous and periosteal sites. Histological analysis revealed bone formation on the outer macropore surface of β-TCP. Some blood vessels formed in the macropores expressed CD31 and CD34, while a few lymphatic vessels expressed CD34 and podoplanin. Thus, the osteoinductive ability of β-TCP alone was demonstrated in humans radiographically for the first time. The histological morphology of β-TCP was demonstrated at an early stage after grafting in humans.展开更多
As a promising technology to improve spectrum efficiency and transmission coverage,Heterogeneous Network(HetNet)has attracted the attention of many scholars in recent years.Additionally,with the introduction of the No...As a promising technology to improve spectrum efficiency and transmission coverage,Heterogeneous Network(HetNet)has attracted the attention of many scholars in recent years.Additionally,with the introduction of the Non-Orthogonal Multiple Access(NOMA)technology,the NOMA-assisted HetNet cannot only improve the system capacity but also allow more users to utilize the same frequency band resource,which makes the NOMA-assisted HetNet a hot topic.However,traditional resource allocation schemes assume that base stations can exactly estimate direct link gains and cross-tier link gains,which is impractical for practical HetNets due to the impact of channel delays and random perturbation.To further improve energy utilization and system robustness,in this paper,we investigate a robust resource allocation problem to maximize the total Energy Efficiency(EE)of Small-Cell Users(SCUs)in NOMA-assisted HetNets under imperfect channel state information.By considering bounded channel uncertainties,the robust resource optimization problem is formulated as a mixed-integer and nonlinear programming problem under the constraints of the cross-tier interference power of macrocell users,the maximum transmit power of small base station,the Resource Block(RB)assignment,and the quality of service requirement of each SCU.The original problem is converted into an equivalent convex optimization problem by using Dinkelbach's method and the successive convex approximation method.A robust Dinkelbach-based iteration algorithm is designed by jointly optimizing the transmit power and the RB allocation.Simulation results verify that the proposed algorithm has better EE and robustness than the existing algorithms.展开更多
Wireless Sensor Networks (WSNs) are mainly deployed for data acquisition, thus, the network performance can be passively measured by exploiting whether application data from various sensor nodes reach the sink. In thi...Wireless Sensor Networks (WSNs) are mainly deployed for data acquisition, thus, the network performance can be passively measured by exploiting whether application data from various sensor nodes reach the sink. In this paper, therefore, we take into account the unique data aggregation communication paradigm of WSNs and model the problem of link loss rates inference as a Maximum-Likelihood Estimation problem. And we propose an inference algorithm based on the standard Expectation-Maximization (EM) techniques. Our algorithm is applicable not only to periodic data collection scenarios but to event detection scenarios. Finally, we validate the algorithm through simulations and it exhibits good performance and scalability.展开更多
This paper is concerned with the in-plane elastic stability of arches subjected to a radial concentrated load. The equilibrium equation for pin-ended circular arches is established by using energy method, and it is pr...This paper is concerned with the in-plane elastic stability of arches subjected to a radial concentrated load. The equilibrium equation for pin-ended circular arches is established by using energy method, and it is proved that the axial force is nearly a constant along the circumference of the circular arches. Based on force method, the equation for the primary eigen function is derived and solved, and the approximate analytical solution of critical instability load is obtained. Numerical examples are given and discussed.展开更多
For strain measurement on offshore jacket platform in deep water, waterproof of strain foil is always an important issue, especially, due to the high pressure in deep water. The waterproof is difficult in two places, ...For strain measurement on offshore jacket platform in deep water, waterproof of strain foil is always an important issue, especially, due to the high pressure in deep water. The waterproof is difficult in two places, one is between the matrix structure and the protection structure, and another is between the lead wires and the protection structure. The surround protection technique discussed in this paper is conventional and ideal, and can be operative for a long time, up to five years. In this method, a metal case and tube is added on the local position, which increases the local rigidity, but the effect on the measurement of strain is not well studied. In this paper, the effect of the surround protection technique on the strain measurement is studied by using numerical and experimental methods, and the results show that the measurement error is well in the range permitted by engineering practice.展开更多
Causal inference has recently garnered significant interest among recommender system(RS)researchers due to its ability to dissect cause-and-effect relationships and its broad applicability across multiple fields.It of...Causal inference has recently garnered significant interest among recommender system(RS)researchers due to its ability to dissect cause-and-effect relationships and its broad applicability across multiple fields.It offers a framework to model the causality in RSs such as confounding effects and deal with counterfactual problems such as offline policy evaluation and data augmentation.Although there are already some valuable surveys on causal recommendations,they typically classify approaches based on the practical issues faced in RS,a classification that may disperse and fragment the uni-fied causal theories.Considering RS researchers’unfamiliarity with causality,it is necessary yet challenging to comprehensively review relevant studies from a coherent causal theoretical perspective,thereby facilitating a deeper integration of causal inference in RS.This survey provides a systematic review of up-to-date papers in this area from a causal theory standpoint and traces the evolutionary development of RS methods within the same causal strategy.First,we introduce the fundamental concepts of causal inference as the basis of the following review.Subsequently,we propose a novel theory-driven taxonomy,categorizing existing methods based on the causal theory employed,namely those based on the potential outcome framework,the structural causal model,and general counterfactuals.The review then delves into the technical details of how existing methods apply causal inference to address particular recommender issues.Finally,we highlight some promising directions for future research in this field.Representative papers and open-source resources will be progressively available at https://github.com/Chrissie-Law/Causal-Inference-forRecommendation.展开更多
Recently,the 2024 Nobel Prizes in Physics and Chemistry were awarded to artificial intelligence(AI)scientists for their groundbreaking contributions.John J.Hopfield and Geoffrey E.Hinton received the Physics Prize for...Recently,the 2024 Nobel Prizes in Physics and Chemistry were awarded to artificial intelligence(AI)scientists for their groundbreaking contributions.John J.Hopfield and Geoffrey E.Hinton received the Physics Prize for their foundational discoveries and inventions that enabled machine learning through artificial neural networks.David Baker was awarded the Chemistry Prize for his work in computational protein design,while Demis Hassabis and John M.Jumper were recognized for their work in protein structure prediction.展开更多
INTRODUCTION.Throughout the scientific discoveries of human history,research paradigms have undergone profound changes.'As shown in Figure 1,from the empirical paradigm,which relies on experimental observation,to ...INTRODUCTION.Throughout the scientific discoveries of human history,research paradigms have undergone profound changes.'As shown in Figure 1,from the empirical paradigm,which relies on experimental observation,to the theoretical paradigm,which is based on theoretical deduction,and further to the computational para-digm,which is associated with simulation and emulation,and finally to the data-driven paradigm,which is grounded in human-machine object integration,every transformation of scientific paradigm has brought about a major leap in science and technology.展开更多
This paper investigates the secure transmission for reconfigurable intelligent surface(RIS)-assisted wireless communication systems.In the studied model,one user connects to the access point via a RIS while an eavesdr...This paper investigates the secure transmission for reconfigurable intelligent surface(RIS)-assisted wireless communication systems.In the studied model,one user connects to the access point via a RIS while an eavesdropper eavesdrops on the signal sent from the user to the access point.Therefore,it is necessary to design an appropriate RIS reflection vector to solve the eavesdropping problem.This problem is formulated as an optimization problem whose goal is to maximize the secure energy efficiency which is defined as the ratio of the secure rate to the total energy consumption of the system via jointly optimizing the RIS reflection reflector as well as the number of RIS elements,which results in a non-convex optimization problem that is intractable to solve by traditional methods.To tackle this issue,a new algorithm by leveraging the advance of the established deep learning(DL)technique is proposed so as to find the optimal RIS reflection vector and determine the optimal number of RIS reflection elements.Simulation results show that the proposed method reaches 96%of the optimal secure energy efficiency of the genie-aided algorithm.展开更多
With advancements in swarm intelligence,artificial intelligence,and wireless mobile network technology,unmanned swarms such as unmanned aerial vehicles,ground vehicles,ships,and other unmanned systems are becoming inc...With advancements in swarm intelligence,artificial intelligence,and wireless mobile network technology,unmanned swarms such as unmanned aerial vehicles,ground vehicles,ships,and other unmanned systems are becoming increasingly autonomous and intelligent.Benefiting from these technologies,intelligent unmanned swarms are able to efficiently perform complex tasks through collaboration in various fields.However,malicious use of intelligent unmanned swarms raises concerns about the potential for significant damage to national infrastructures such as airports and power facilities.Defending against malicious activities is essential but challenging due to the swarms’abilities to perceive,understand complex environments.展开更多
Ammonia synthesis by electrochemical nitrogen reduction technique is an attractive alternative to traditional Haber-Bosch process.Currently,development of an efficient and effective electrocatalyst is one of the remai...Ammonia synthesis by electrochemical nitrogen reduction technique is an attractive alternative to traditional Haber-Bosch process.Currently,development of an efficient and effective electrocatalyst is one of the remaining key challenges.In this work,density functional theory(DFT)computations were systematically employed on double transition metal atoms(Fe,Co,Ni,Cu and Mo)anchored Graphdiyne(GDY)for nitrogen reduction reaction(NRR).The Co-Ni heteronuclear complex and Mo-Mo homonuclear complex showed the highest NRR activity while demonstrating synergistic effect of double atomic catalytic sites towards the promising NRR activity.展开更多
基金Basic and Applied Basic Research Foundation of Guangdong Province,Grant/Award Numbers:2021A1515110245,2022A1515140108,2023B1515040013National Youth Top-notch Talent Support Program,Grant/Award Number:x2qsA4210090+5 种基金Guangzhou Key Research and Development Program,Grant/Award Number:SL2022B03J01256Guangdong Provincial Key Laboratory of Distributed Energy Systems,Grant/Award Number:2020B1212060075Engineering Research Center of None-food Biomass Efficient Pyrolysis and Utilization Technology of Guangdong Higher Education Institutes,Grant/Award Number:2016GCZX009State Key Laboratory of Pulp and Paper Engineering,Grant/Award Numbers:202215,2022PY02Key projects of social science and technology development in Dongguan,Grant/Award Number:20231800936352National Natural Science Foundation of China,Grant/Award Numbers:21736003,21905044,31971614,32071714。
文摘Metal-organic frameworks recently have been burgeoning and used as precursors to obtain various metal-nitrogen-carbon catalysts for oxygen reduction reaction(ORR).Although rarely studied,Mn-N-C is a promising catalyst for ORR due to its weak Fenton reaction activity and strong graphitization catalysis.Here,we developed a facile strategy for anchoring the atomically dispersed nitrogen-coordinated single Mn sites on carbon nanosheets(MnNCS)from an Mn-hexamine coordination framework.The atomically dispersed Mn-N_(4) sites were dispersed on ultrathin carbon nanosheets with a hierarchically porous structure.The optimized MnNCS displayed an excellent ORR performance in half-cells(0.89 V vs.reversible hydrogen electrode(RHE)in base and 0.76 V vs.RHE in acid in half-wave potential)and Zn-air batteries(233 mW cm^(−2)in peak power density),along with significantly enhanced stability.Density functional theory calculations further corroborated that the Mn-N_(4)-C(12)site has favorable adsorption of*OH as the rate-determining step.These findings demonstrate that the metal-hexamine coordination framework can be used as a model system for the rational design of highly active atomic metal catalysts for energy applications.
文摘Objective: The purpose of this study was to evaluate the difference in alcohol use between urban and rural students of Inner Mongolia Medical University. Methods: A cross-sectional census was conducted on medical students on campus in 2013. We use multivariate logistic regression models to assess the factors associated with alcohol use. We further use chi-square test assess on differences in alcohol use between urban and rural people among significance factors in logistic regression models. Results: The prevalence of alcohol use among students in rural area was higher than that in urban area (p = 0.016). Alcohol use was associated with Gender, monthly expenses, residence, ethnic and faculty. The odds of alcohol use for Mongolia students were 1.139 times higher than that for Han students. The prevalence of alcohol consumption among students from pharmacy or Traditional Chinese Medicine and Mongolian Medicine faculties in rural area was higher than that among student in urban area (p = 0.03;p = 0.001). The prevalence of alcohol use among female students in rural area was higher than that among female students in urban area (p < 0.043). The proportion of alcohol use among students with <600 in rural area was higher than that among students in urban area (p < 0.001). Conclusion: Considering the differences in the prevalence of alcohol use between rural area and urban area, university administrators aiming at students from various regions develop various approaches.
基金supported by the National Natural Science Foundation of China (Grant No.61601071)the Scientific and Technological Research Program of Chongqing Municipal Education Commission (Grant No.KJ16004012)+2 种基金the Municipal Natural Science Foundation of Chongqing (Grant No.CSTC2016JCYJA2197)the Seventeenth Open Foundation of State Key Lab of Integrated Services Networks of Xidian University (Grant No.ISN17-01)the Dr. Startup Founds of Chongqing University of Posts and Telecommunications (Grant No.A2016-12)
文摘Heterogeneous network(HetNet) as a promising technology to improve spectrum efficiency and system capacity has been concerned by many scholars, which brings huge challenges for power allocation and interference management in multicell network structures. Although some works have been done for power allocation in heterogeneous femtocell networks, most of them focus centralized schemes for single-cell network under interference constraint of macrocell user. In this paper, a sum-rate maximization based power allocation algorithm is proposed for a downlink cognitive Het Net with one macrocell network and multiple microcell networks. The original power allocation optimization problem with the consideration of cross-tier interference constraint, maximum transmit power constraint of microcell base station and inter-cell interference of microcell networks is converted into a geometric programming problem which can be solved by Lagrange dual method in a distributed way. Simulation results demonstrate the performance and effectiveness of the proposed algorithm by comparing with the equal power allocation scheme.
文摘Mutual synchronization is a ubiquitous phenomenon that exists in various natural systems. The individual participants in this process can be modeled as oscillators, which interact by discrete pulses. In this paper, we analyze the synchronization condition of two- and multi-oscillators system, and propose a linear pulse-coupled oscillators model. We prove that the proposed model can achieve synchronization for almost all conditions. Numerical simulations are also included to investigate how different model parameters affect the synchronization. We also discuss the implementation of the model as a new approach for time synchronization in wireless sensor networks.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFC1511300)the National Natural Science Foundation of China(Grant No.U21A20447 and 61971079)+2 种基金the Basic Research and Frontier Exploration Project of Chongqing (Grant No.cstc2019jcyj-msxmX0666)the Innovative Group Project of the National Natural Science Foundation of Chongqing (Grant No.cstc2020jcyj-cxttX0002)the Regional Creative Cooperation Program of Sichuan (2020YFQ0025).
文摘The Multiple-Input Multiple-Output(MIMO)Non-Orthogonal Multiple Access(NOMA)based on Spatial Modulation(SM-MIMO-NOMA)system has been proposed to achieve better spectral efficiency with reduced radio frequency chains comparing to the traditional MIMO-NOMA system.To improve the performance of SM-MIMO-NOMA systems,we extend them to generalized spatial modulation scenarios while maintaining moderate complexity and fairness.In this paper,system spectral efficiency and transmission quality improvements are proposed by investigating a sum-rate maximization resource allocation problem that is subject to the total transmitted power,user grouping,and resource block constraints.To solve this non-convex and difficult problem,a graph-based user grouping strategy is proposed initially to maximize the mutual gains of intragroup users.An auxiliary-variable approach is then adopted to transform the power allocation subproblem into a convex one.Simulation results demonstrate that the proposed algorithm has better performance in terms of bit error rate and sum rates.
文摘Osteoinductive properties of β-TCP remain unknown in humans. It is important to improve the bone grafts which have been the standard treatment for bone defect due to their biocompatibility and bone-healing properties. The purpose of this study was to radiologically clarify the bone forming property of β-TCP by evaluating the replacement of β-TCP by newly formed bone in the defect after fibular resection and to examine the histological features of a β-TCP specimen three months after grafting. Radiographs of 17 patients who underwent β-TCP grafting were evaluated. Osteoinductive and osteoconductive properties were assessed by examining bone formation from the remnant fibula, periosteum, and β-TCP alone. In one case, β-TCP was removed later because of postoperative complications and was evaluated histologically. Twenty two of 34 sites between the remnant fibula and β-TCP had achieved good bone regeneration. Five of 14 sites between the periosteum and β-TCP had achieved good bone regeneration. We found immature but evident bone formation in three cases with no osseous and periosteal sites. Histological analysis revealed bone formation on the outer macropore surface of β-TCP. Some blood vessels formed in the macropores expressed CD31 and CD34, while a few lymphatic vessels expressed CD34 and podoplanin. Thus, the osteoinductive ability of β-TCP alone was demonstrated in humans radiographically for the first time. The histological morphology of β-TCP was demonstrated at an early stage after grafting in humans.
基金This work was supported by the National Natural Science Foundation of China(No.61601071,62071078)the National Key Research and Development Program of China(No.2019YFC1511300)+2 种基金the Natural Science Foundation of Chongqing(No.cstc2019jcyj-xfkxX0002)the Chongqing Entrepreneurship and Innovation Program for the Returned Overseas Chinese Scholars(No.cx2020095)the Graduate Scientific Research Innovation Project of Chongqing(No.CYS20251,CYS20253).
文摘As a promising technology to improve spectrum efficiency and transmission coverage,Heterogeneous Network(HetNet)has attracted the attention of many scholars in recent years.Additionally,with the introduction of the Non-Orthogonal Multiple Access(NOMA)technology,the NOMA-assisted HetNet cannot only improve the system capacity but also allow more users to utilize the same frequency band resource,which makes the NOMA-assisted HetNet a hot topic.However,traditional resource allocation schemes assume that base stations can exactly estimate direct link gains and cross-tier link gains,which is impractical for practical HetNets due to the impact of channel delays and random perturbation.To further improve energy utilization and system robustness,in this paper,we investigate a robust resource allocation problem to maximize the total Energy Efficiency(EE)of Small-Cell Users(SCUs)in NOMA-assisted HetNets under imperfect channel state information.By considering bounded channel uncertainties,the robust resource optimization problem is formulated as a mixed-integer and nonlinear programming problem under the constraints of the cross-tier interference power of macrocell users,the maximum transmit power of small base station,the Resource Block(RB)assignment,and the quality of service requirement of each SCU.The original problem is converted into an equivalent convex optimization problem by using Dinkelbach's method and the successive convex approximation method.A robust Dinkelbach-based iteration algorithm is designed by jointly optimizing the transmit power and the RB allocation.Simulation results verify that the proposed algorithm has better EE and robustness than the existing algorithms.
文摘Wireless Sensor Networks (WSNs) are mainly deployed for data acquisition, thus, the network performance can be passively measured by exploiting whether application data from various sensor nodes reach the sink. In this paper, therefore, we take into account the unique data aggregation communication paradigm of WSNs and model the problem of link loss rates inference as a Maximum-Likelihood Estimation problem. And we propose an inference algorithm based on the standard Expectation-Maximization (EM) techniques. Our algorithm is applicable not only to periodic data collection scenarios but to event detection scenarios. Finally, we validate the algorithm through simulations and it exhibits good performance and scalability.
文摘This paper is concerned with the in-plane elastic stability of arches subjected to a radial concentrated load. The equilibrium equation for pin-ended circular arches is established by using energy method, and it is proved that the axial force is nearly a constant along the circumference of the circular arches. Based on force method, the equation for the primary eigen function is derived and solved, and the approximate analytical solution of critical instability load is obtained. Numerical examples are given and discussed.
文摘For strain measurement on offshore jacket platform in deep water, waterproof of strain foil is always an important issue, especially, due to the high pressure in deep water. The waterproof is difficult in two places, one is between the matrix structure and the protection structure, and another is between the lead wires and the protection structure. The surround protection technique discussed in this paper is conventional and ideal, and can be operative for a long time, up to five years. In this method, a metal case and tube is added on the local position, which increases the local rigidity, but the effect on the measurement of strain is not well studied. In this paper, the effect of the surround protection technique on the strain measurement is studied by using numerical and experimental methods, and the results show that the measurement error is well in the range permitted by engineering practice.
基金This review is supported by the National Key Research and Development Program of China under grant no.2021ZD0113602the National Natural Science Foundation of China under grant nos.62176014 and 62276015the Fundamental Research Funds for the Central Universities.
文摘Causal inference has recently garnered significant interest among recommender system(RS)researchers due to its ability to dissect cause-and-effect relationships and its broad applicability across multiple fields.It offers a framework to model the causality in RSs such as confounding effects and deal with counterfactual problems such as offline policy evaluation and data augmentation.Although there are already some valuable surveys on causal recommendations,they typically classify approaches based on the practical issues faced in RS,a classification that may disperse and fragment the uni-fied causal theories.Considering RS researchers’unfamiliarity with causality,it is necessary yet challenging to comprehensively review relevant studies from a coherent causal theoretical perspective,thereby facilitating a deeper integration of causal inference in RS.This survey provides a systematic review of up-to-date papers in this area from a causal theory standpoint and traces the evolutionary development of RS methods within the same causal strategy.First,we introduce the fundamental concepts of causal inference as the basis of the following review.Subsequently,we propose a novel theory-driven taxonomy,categorizing existing methods based on the causal theory employed,namely those based on the potential outcome framework,the structural causal model,and general counterfactuals.The review then delves into the technical details of how existing methods apply causal inference to address particular recommender issues.Finally,we highlight some promising directions for future research in this field.Representative papers and open-source resources will be progressively available at https://github.com/Chrissie-Law/Causal-Inference-forRecommendation.
文摘Recently,the 2024 Nobel Prizes in Physics and Chemistry were awarded to artificial intelligence(AI)scientists for their groundbreaking contributions.John J.Hopfield and Geoffrey E.Hinton received the Physics Prize for their foundational discoveries and inventions that enabled machine learning through artificial neural networks.David Baker was awarded the Chemistry Prize for his work in computational protein design,while Demis Hassabis and John M.Jumper were recognized for their work in protein structure prediction.
基金National Natural Science Foundation of China under grants 62372430 and 62206266Youth Innovation Promotion Association CAS under grant 2023112.
文摘INTRODUCTION.Throughout the scientific discoveries of human history,research paradigms have undergone profound changes.'As shown in Figure 1,from the empirical paradigm,which relies on experimental observation,to the theoretical paradigm,which is based on theoretical deduction,and further to the computational para-digm,which is associated with simulation and emulation,and finally to the data-driven paradigm,which is grounded in human-machine object integration,every transformation of scientific paradigm has brought about a major leap in science and technology.
基金China National Key R&D Program(2021YFA1000500)National Natural Science Foundation of China(62101492)+7 种基金Zhejiang Provincial Natural Science Foundation of China(LR22F010002)Natural Science Foundation of Jiangsu Province of China(BK20210641)Natural Science Foundation of Jiangsu Province of China(BK20210641)Engineering and Physical Sciences Research Council(EPSRC)(EP/P022723/1)National Natural Science Foundation of China(62271094)Key Fund of Natural Science Foundation of Chongqing(CSTB2022NSCQLZX0009)Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJZD-K202200601)China Postdoctoral Science Foundation(2022MD723725)。
文摘This paper investigates the secure transmission for reconfigurable intelligent surface(RIS)-assisted wireless communication systems.In the studied model,one user connects to the access point via a RIS while an eavesdropper eavesdrops on the signal sent from the user to the access point.Therefore,it is necessary to design an appropriate RIS reflection vector to solve the eavesdropping problem.This problem is formulated as an optimization problem whose goal is to maximize the secure energy efficiency which is defined as the ratio of the secure rate to the total energy consumption of the system via jointly optimizing the RIS reflection reflector as well as the number of RIS elements,which results in a non-convex optimization problem that is intractable to solve by traditional methods.To tackle this issue,a new algorithm by leveraging the advance of the established deep learning(DL)technique is proposed so as to find the optimal RIS reflection vector and determine the optimal number of RIS reflection elements.Simulation results show that the proposed method reaches 96%of the optimal secure energy efficiency of the genie-aided algorithm.
基金supported by the Youth Innovation Promotion Association CAS.
文摘With advancements in swarm intelligence,artificial intelligence,and wireless mobile network technology,unmanned swarms such as unmanned aerial vehicles,ground vehicles,ships,and other unmanned systems are becoming increasingly autonomous and intelligent.Benefiting from these technologies,intelligent unmanned swarms are able to efficiently perform complex tasks through collaboration in various fields.However,malicious use of intelligent unmanned swarms raises concerns about the potential for significant damage to national infrastructures such as airports and power facilities.Defending against malicious activities is essential but challenging due to the swarms’abilities to perceive,understand complex environments.
基金the financial support by Guangdong Innovation Research Team for Higher Education(2017KCXTD030)High-level Talents Project of Dongguan University of Technology(KCYKYQD2017017)Engineering Research Center of None-food Biomass Efficient Pyrolysis and Utilization Technology of Guangdong Higher Education Institutes(2016GCZX009)。
文摘Ammonia synthesis by electrochemical nitrogen reduction technique is an attractive alternative to traditional Haber-Bosch process.Currently,development of an efficient and effective electrocatalyst is one of the remaining key challenges.In this work,density functional theory(DFT)computations were systematically employed on double transition metal atoms(Fe,Co,Ni,Cu and Mo)anchored Graphdiyne(GDY)for nitrogen reduction reaction(NRR).The Co-Ni heteronuclear complex and Mo-Mo homonuclear complex showed the highest NRR activity while demonstrating synergistic effect of double atomic catalytic sites towards the promising NRR activity.