Most of the neural network architectures are based on human experience,which requires a long and tedious trial-and-error process.Neural architecture search(NAS)attempts to detect effective architectures without human ...Most of the neural network architectures are based on human experience,which requires a long and tedious trial-and-error process.Neural architecture search(NAS)attempts to detect effective architectures without human intervention.Evolutionary algorithms(EAs)for NAS can find better solutions than human-designed architectures by exploring a large search space for possible architectures.Using multiobjective EAs for NAS,optimal neural architectures that meet various performance criteria can be explored and discovered efficiently.Furthermore,hardware-accelerated NAS methods can improve the efficiency of the NAS.While existing reviews have mainly focused on different strategies to complete NAS,a few studies have explored the use of EAs for NAS.In this paper,we summarize and explore the use of EAs for NAS,as well as large-scale multiobjective optimization strategies and hardware-accelerated NAS methods.NAS performs well in healthcare applications,such as medical image analysis,classification of disease diagnosis,and health monitoring.EAs for NAS can automate the search process and optimize multiple objectives simultaneously in a given healthcare task.Deep neural network has been successfully used in healthcare,but it lacks interpretability.Medical data is highly sensitive,and privacy leaks are frequently reported in the healthcare industry.To solve these problems,in healthcare,we propose an interpretable neuroevolution framework based on federated learning to address search efficiency and privacy protection.Moreover,we also point out future research directions for evolutionary NAS.Overall,for researchers who want to use EAs to optimize NNs in healthcare,we analyze the advantages and disadvantages of doing so to provide detailed guidance,and propose an interpretable privacy-preserving framework for healthcare applications.展开更多
Multimodal sentiment analysis utilizes multimodal data such as text,facial expressions and voice to detect people’s attitudes.With the advent of distributed data collection and annotation,we can easily obtain and sha...Multimodal sentiment analysis utilizes multimodal data such as text,facial expressions and voice to detect people’s attitudes.With the advent of distributed data collection and annotation,we can easily obtain and share such multimodal data.However,due to professional discrepancies among annotators and lax quality control,noisy labels might be introduced.Recent research suggests that deep neural networks(DNNs)will overfit noisy labels,leading to the poor performance of the DNNs.To address this challenging problem,we present a Multimodal Robust Meta Learning framework(MRML)for multimodal sentiment analysis to resist noisy labels and correlate distinct modalities simultaneously.Specifically,we propose a two-layer fusion net to deeply fuse different modalities and improve the quality of the multimodal data features for label correction and network training.Besides,a multiple meta-learner(label corrector)strategy is proposed to enhance the label correction approach and prevent models from overfitting to noisy labels.We conducted experiments on three popular multimodal datasets to verify the superiority of ourmethod by comparing it with four baselines.展开更多
LncRNA(long non-coding RNA) H19 is a transcript of the H19 gene that is expressed during embryogenesis.We previously discove red a role for circular lncRNA H19 in the onset and prognosis of cerebral ischemic stroke.In...LncRNA(long non-coding RNA) H19 is a transcript of the H19 gene that is expressed during embryogenesis.We previously discove red a role for circular lncRNA H19 in the onset and prognosis of cerebral ischemic stroke.In this study,we used serum from patients with ischemic stroke,and mouse and cell culture models to elucidate the roles of plasma and neuronal exosomes in the regulatory effect of lncRNA H19 on insulin-like growth factor-1 and its mechanism in ischemic stroke,using western blotting,quantitative real-time polymerase chain reaction,and enzyme-linked immunosorbent assays.Plasma exosomal IncRNA H19 was negatively associated with blood levels of insulin-like growth factor-1 in samples from patients with cerebral ischemic stroke.In a mouse model,levels of exosomal IncRNA H19 were positively correlated with plasma and cerebral lncRNA H19.In a cell co-culture model,we confirmed that IncRNA H19 was transported from neuro ns to astrocytes by exosomes to induce downregulation of insulin-like growth factor-1 through the H19/let-7 a/insulin-like growth factor-1 receptor axis.This study provides the first evidence for the transpo rtation of IncRNA H19 by exosomes and the relationship between IncRNA H19 and insulinlike growth factor-1.展开更多
Network slicing is envisioned as one of the key techniques to meet the extremely diversified service requirements of the Internet of Things(IoT)as it provides an enhanced user experience and elastic resource configura...Network slicing is envisioned as one of the key techniques to meet the extremely diversified service requirements of the Internet of Things(IoT)as it provides an enhanced user experience and elastic resource configuration.In the context of slicing enhanced IoT networks,both the Service Provider(SP)and Infrastructure Provider(InP)face challenges of ensuring efficient slice construction and high profit in dynamic environments.These challenges arise from randomly generated and departed slice requests from end-users,uncertain resource availability,and multidimensional resource allocation.Admission and resource allocation for distinct demands of slice requests are the key issues in addressing these challenges and should be handled effectively in dynamic environments.To this end,we propose an Opportunistic Admission and Resource allocation(OAR)policy to deal with the issues of random slicing requests,uncertain resource availability,and heterogeneous multi-resources.The key idea of OAR is to allow the SP to decide whether to accept slice requests immediately or defer them according to the load and price of resources.To cope with the random slice requests and uncertain resource availability,we formulated this issue as a Markov Decision Process(MDP)to obtain the optimal admission policy,with the aim of maximizing the system reward.Furthermore,the buyer-seller game theory approach was adopted to realize the optimal resource allocation,while motivating each SP and InP to maximize their rewards.Our numerical results show that the proposed OAR policy can make reasonable decisions effectively and steadily,and outperforms the baseline schemes in terms of the system reward.展开更多
In order to solve the high latency of traditional cloud computing and the processing capacity limitation of Internet of Things(IoT)users,Multi-access Edge Computing(MEC)migrates computing and storage capabilities from...In order to solve the high latency of traditional cloud computing and the processing capacity limitation of Internet of Things(IoT)users,Multi-access Edge Computing(MEC)migrates computing and storage capabilities from the remote data center to the edge of network,providing users with computation services quickly and directly.In this paper,we investigate the impact of the randomness caused by the movement of the IoT user on decision-making for offloading,where the connection between the IoT user and the MEC servers is uncertain.This uncertainty would be the main obstacle to assign the task accurately.Consequently,if the assigned task cannot match well with the real connection time,a migration(connection time is not enough to process)would be caused.In order to address the impact of this uncertainty,we formulate the offloading decision as an optimization problem considering the transmission,computation and migration.With the help of Stochastic Programming(SP),we use the posteriori recourse to compensate for inaccurate predictions.Meanwhile,in heterogeneous networks,considering multiple candidate MEC servers could be selected simultaneously due to overlapping,we also introduce the Multi-Arm Bandit(MAB)theory for MEC selection.The extensive simulations validate the improvement and effectiveness of the proposed SP-based Multi-arm bandit Method(SMM)for offloading in terms of reward,cost,energy consumption and delay.The results showthat SMMcan achieve about 20%improvement compared with the traditional offloading method that does not consider the randomness,and it also outperforms the existing SP/MAB based method for offloading.展开更多
Microalgae biomass is an ideal precursor to prepare renewable carbon materials,which has broad application.The bioaccumulation efficiency(lipids,proteins,carbohydrates)and biomass productivity of microalgae are influe...Microalgae biomass is an ideal precursor to prepare renewable carbon materials,which has broad application.The bioaccumulation efficiency(lipids,proteins,carbohydrates)and biomass productivity of microalgae are influenced by spectroscopy during the culture process.In this study,a bilayer plate-type photobioreactor was designed to cultivate Chlorella protothecoides with spectral selectivity by nanofluids.Compared to culture without spectral selectivity,the spectral selectivity of Ag/CoSO_(4)nanofluids increased microalgae biomass by 5.76%,and the spectral selectivity of CoSO_(4)solution increased by 17.14%.In addition,the spectral selectivity of Ag/CoSO_(4)nanofluids was more conducive to the accumulation of nutrients(29.46%lipids,50.66%proteins,and 17.86%carbohydrates)in microalgae.Further cultured chlorella was utilized to prepare bioelectrode materials,it was found that algal based biochar had a good pore structure(micro specific surface area:1627.5314 m^(2)/g,average pore size:0.21294 nm).As the current density was 1 A/g,the specific capacitance reached 230 F/g,appearing good electrochemical performance.展开更多
In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no...In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no technical analysis and comparison as a guideline to determine which type of consensus mechanism should be adopted in a specific scenario/application.To this end,this work investigates three mainstream consensus mechanisms in the blockchain,namely,Proof of Work(PoW),Proof of Stake(PoS),and Direct Acyclic Graph(DAG),and identifies their performances in terms of the average time to generate a new block,the confirmation delay,the Transaction Per Second(TPS)and the confirmation failure probability.The results show that the consensus process is affected by both network resource(computation power/coin age,buffer size)and network load conditions.In addition,it shows that PoW and PoS are more sensitive to the change of network resource while DAG is more sensitive to network load conditions.展开更多
MXenes,a new family of two-dimensional(2D)materials with excellent electronic conductivity and hydrophilicity,have shown distinctive advantages as a highly conductive matrix material for lithium-ion battery anodes.Her...MXenes,a new family of two-dimensional(2D)materials with excellent electronic conductivity and hydrophilicity,have shown distinctive advantages as a highly conductive matrix material for lithium-ion battery anodes.Herein,a facile electrostatic self-assembly of SnO2 quantum dots(QDs)on Ti3C2Tx MXene sheets is proposed.The as-prepared SnO2/MXene hybrids have a unique 0D-2D structure,in which the 0D SnO2 QDs(~4.7 nm)are uniformly distributed over 2D Ti3C2Tx MXene sheets with controllable loading amount.The SnO2 QDs serve as a high capacity provider and the“spacer”to prevent the MXene sheets from restacking;the highly conductive Ti3C2Tx MXene can not only provide efficient pathways for fast transport of electrons and Li ions,but also buffer the volume change of SnO2 during lithiation/delithiation by confining SnO2 QDs between the MXene nanosheets.Therefore,the 0D-2D SnO2 QDs/MXene hybrids deliver superior lithium storage properties with high capacity(887.4 mAh g?1 at 50 mA g?1),stable cycle performance(659.8 mAh g?1 at 100 mA g?1 after 100 cycles with a capacity retention of 91%)and excellent rate performance(364 mAh g?1 at 3 A g?1),making it a promising anode material for lithium-ion batteries.展开更多
ZnS has great potentials as an anode for lithium storage because of its high theoretical capacity and resource abundance;however,the large volume expansion accompanied with structural collapse and low conductivity of ...ZnS has great potentials as an anode for lithium storage because of its high theoretical capacity and resource abundance;however,the large volume expansion accompanied with structural collapse and low conductivity of ZnS cause severe capacity fading and inferior rate capability during lithium storage. Herein,0D-2 D ZnS nanodots/Ti_(3)C_(2)T_x MXene hybrids are prepared by anchoring ZnS nanodots on Ti_(3)C_(2)T_(x) MXene nanosheets through coordination modulation between MXene and MOF precursor(ZIF-8) followed with sulfidation. The MXene substratecoupled with the ZnS nanodots can synergistically accommodate volume variation of ZnS over charge–discharge to realize stable cyclability. As revealed by XPS characterizations and DFT calculations,the strong interfacial interaction between ZnS nanodots and MXene nanosheets can boost fast electron/lithium-ion transfer to achieve excellent electrochemical activity and kinetics for lithium storage. Thereby,the as-prepared ZnS nanodots/MXene hybrid exhibits a high capacity of 726.8 mAh g^(-1) at 30 mA g^(-1),superior cyclic stability(462.8 mAh g^(-1) after 1000 cycles at 0.5 A g^(-1)),and excellent rate performance. The present results provide new insights into the understanding of the lithium storage mechanism of ZnS and the revealing of the e ects of interfacial interaction on lithium storage performance enhancement.展开更多
The sixth-generation(6G)network must provide better performance than previous generations to meet the requirements of emerging services and applications,such as multi-gigabit transmission rate,higher reliability,and s...The sixth-generation(6G)network must provide better performance than previous generations to meet the requirements of emerging services and applications,such as multi-gigabit transmission rate,higher reliability,and sub-1 ms latency and ubiquitous connection for the Internet of Everything(IoE).However,with the scarcity of spectrum resources,efficient resource management and sharing are crucial to achieving all these ambitious requirements.One possible technology to achieve all this is the blockchain.Because of its inherent properties,the blockchain has recently gained an important position,which is of great significance to the 6G network and other networks.In particular,the integration of the blockchain in 6G will enable the network to monitor and manage resource utilization and sharing efficiently.Hence,in this paper,we discuss the potentials of the blockchain for resource management and sharing in 6G using multiple application scenarios,namely,Internet of things,deviceto-device communications,network slicing,and inter-domain blockchain ecosystems.展开更多
The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performa...The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performance analysis,most of them only address the intentional forking caused by a malicious attacker.In fact,without any attacker,unintentional forking still remains due to transmission delay and failure,especially in wireless network scenarios.To this end,this paper investigates the reason for generating unintentional forking and derives the forking probability expression in Wireless Blockchain Networks(WBN).Furthermore,in order to illustrate the unintentional forking on the blockchain system,the performances in terms of resource utilization rate,block generation time,and Transaction Per Second(TPS)are investigated.The numerical results show that the target difficulty of hash algorithm in generating a new block,the delay time of broadcasting,the network scale,and the transmission failure probability would affect the unintentional forking probability significantly,which can provide a reliable basis for avoiding forking to save resource consumption and improving system performance.展开更多
Objective:To explore whether the traditional Chinese medicine(TCM)Bu Jing Yi Shi Tablets alters the expression of scleral TGF-b1 and Smad3 in guinea pigs with formdeprivation myopia(FDM).Methods:Sixty-five guinea pigs...Objective:To explore whether the traditional Chinese medicine(TCM)Bu Jing Yi Shi Tablets alters the expression of scleral TGF-b1 and Smad3 in guinea pigs with formdeprivation myopia(FDM).Methods:Sixty-five guinea pigs were randomly divided into control,model,low-,medium-,and high-dose treatment groups.Except for the control group,FDM was induced by covering the right eye of each animal with opaque latex.The treatment groups were gavaged with different suspension concentrations of Bu Jing Yi Shi Tablets.Refraction and axial length were performed before and after myopia induction.At the end of the experiment,all right eyes were extracted,and scleral sections were prepared for staining and TGF-b1 and Smad3 immunohistochemistry.Scleral thickness and area,the scleral fibroblast quantity,and scleral TGFb1 and Smad3 expressions were measured.Results:The 5 FDM groups had the same initial axial length and diopter,the final diopter and axial length of the model group were significantly increased compared with the control group and treatment groups(P<.01).The axial length of each treatment group decreased as the dose decreased compared with the model group(P<.01);the total scleral area(P<.05 e.01)and the number of scleral fibroblasts(P<.01)in the model group were significantly lower than the treatment groups.Both the TGF-b1 and Smad3 integral optical densities in the model group were significantly lower than the control and medium-and high-dose treatment groups(P<.01).TGF-b1 and Smad3 mRNAs in the model group were decreased compared with the control group,but increased in expression after treatment.展开更多
Mobile edge caching technology is gaining more and more attention because it can effectively improve the Quality of Experience (QoE) of users and reduce backhaul burden. This paper aims to improve the utility of mobil...Mobile edge caching technology is gaining more and more attention because it can effectively improve the Quality of Experience (QoE) of users and reduce backhaul burden. This paper aims to improve the utility of mobile edge caching technology from the perspectie of caching resource management by examining a network composed of one operator, multiple users and Content Providers (CPs). The caching resource management model is constructed on the premise of fully considering the QoE of users and the servicing capability of the Base Station (BS). In order to create the best caching resource allocation scheme, the original problem is transformed into a multi-leader multi-follower Stackelberg game model through the analysis of the system model. The strategy combinations and the utility functions of players are analyzed. The existence and uniqueness of the Nash Equilibrium (NE) solution are also analyzed and proved. The optimal strategy combinations and the best responses are deduced in detail. Simulation results and analysis show that the proposed model and algorithm can achieve the optimal allocation of caching resource and improve the QoE of users.展开更多
The steady fusion plasma operation is constrained by tungsten(W)material sputtering issue in the EAST tokamak.In this work,the suppression of W sputtering source has been studied by advanced wall conditionings.It is a...The steady fusion plasma operation is constrained by tungsten(W)material sputtering issue in the EAST tokamak.In this work,the suppression of W sputtering source has been studied by advanced wall conditionings.It is also concluded that the W sputtering yield becomes more with increasing carbon(C)content in the main deuterium(D)plasma.In EAST,the integrated use of discharge cleanings and lithium(Li)coating has positive effects on the suppression of W sputtering source.In the plasma recovery experiments,it is suggested that the W intensity is reduced by approximately 60%with the help of~35 h Ion Cyclotron Radio Frequency Discharge Cleaning(ICRF-DC)and~40 g Li coating after vacuum failure.The first wall covered by Li film could be relieved from the bombardment of energetic particles,and the impurity in the vessel would be removed through the particle induced desorption and isotope exchange during the discharge cleanings.In general,the sputtering yield of W would decrease from the source,on the bias of the improvement of wall condition and the mitigation of plasmawall interaction process.It lays important base of the achievement of high-parameter and longpulse plasma operation in EAST.The experiences also would be constructive for us to promote the understanding of relevant physics and basis towards the ITER-like condition.展开更多
With the increasing demand for petroleum resources and environmental issues,new energy electric vehicles are increasingly being used.However,the large number of electric vehicles connected to the grid has brought new ...With the increasing demand for petroleum resources and environmental issues,new energy electric vehicles are increasingly being used.However,the large number of electric vehicles connected to the grid has brought new challenges to the operation of the grid.Firstly,A novel bidirectional interaction model is established based on modulation theory with nonlinear loads.Then,the electric energy measuring scheme of EVs for V2G is derived under the conditions of distorted power loads.The scheme is composed of fundamental electric energy,fundamental-distorted electric energy,distorted-fundamental electric energy and distorted electric energy.And the characteristics of each electric energy are analyzed.Finally,the correctness of the model and energy measurement method is verified by three simulation cases:the impact signals,the fluctuating signals,and the harmonic signals.展开更多
Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating...Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating spring, summer, autumn and winter air temperatures and mean annual air temperature(MAAT) from 1960 through 2008 over the Heihe River Basin reveals a statistically significant trend of 0.31 °C/decade, 0.28 °C/decade, 0.37 °C/decade, 0.50 °C/decade, and 0.37 °C /decade, respectively. The averaged time series of mean annual ground surface temperature(MAGST) and maximum annual ground surface temperature(MaxAGST) for 1972–2006 over the basin indicates a statistically significant trend of 0.58 °C/decade and 1.27 °C/decade, respectively. The minimum annual ground surface temperature(MinAGST) in the same period remains unchanged as a whole. Estimating surface freezing/thawing index as well as the ratio of freezing index to thawing index(RFT) in the period between 1959 and 2006 over the basin indicates a statistically significant trend of-42.5 °C-day/decade, 85.4 °C-day/decade and-0.018/decade, respectively.展开更多
基金supported in part by the National Natural Science Foundation of China (NSFC) under Grant No.61976242in part by the Natural Science Fund of Hebei Province for Distinguished Young Scholars under Grant No.F2021202010+2 种基金in part by the Fundamental Scientific Research Funds for Interdisciplinary Team of Hebei University of Technology under Grant No.JBKYTD2002funded by Science and Technology Project of Hebei Education Department under Grant No.JZX2023007supported by 2022 Interdisciplinary Postgraduate Training Program of Hebei University of Technology under Grant No.HEBUT-YXKJC-2022122.
文摘Most of the neural network architectures are based on human experience,which requires a long and tedious trial-and-error process.Neural architecture search(NAS)attempts to detect effective architectures without human intervention.Evolutionary algorithms(EAs)for NAS can find better solutions than human-designed architectures by exploring a large search space for possible architectures.Using multiobjective EAs for NAS,optimal neural architectures that meet various performance criteria can be explored and discovered efficiently.Furthermore,hardware-accelerated NAS methods can improve the efficiency of the NAS.While existing reviews have mainly focused on different strategies to complete NAS,a few studies have explored the use of EAs for NAS.In this paper,we summarize and explore the use of EAs for NAS,as well as large-scale multiobjective optimization strategies and hardware-accelerated NAS methods.NAS performs well in healthcare applications,such as medical image analysis,classification of disease diagnosis,and health monitoring.EAs for NAS can automate the search process and optimize multiple objectives simultaneously in a given healthcare task.Deep neural network has been successfully used in healthcare,but it lacks interpretability.Medical data is highly sensitive,and privacy leaks are frequently reported in the healthcare industry.To solve these problems,in healthcare,we propose an interpretable neuroevolution framework based on federated learning to address search efficiency and privacy protection.Moreover,we also point out future research directions for evolutionary NAS.Overall,for researchers who want to use EAs to optimize NNs in healthcare,we analyze the advantages and disadvantages of doing so to provide detailed guidance,and propose an interpretable privacy-preserving framework for healthcare applications.
基金supported by STI 2030-Major Projects 2021ZD0200400National Natural Science Foundation of China(62276233 and 62072405)Key Research Project of Zhejiang Province(2023C01048).
文摘Multimodal sentiment analysis utilizes multimodal data such as text,facial expressions and voice to detect people’s attitudes.With the advent of distributed data collection and annotation,we can easily obtain and share such multimodal data.However,due to professional discrepancies among annotators and lax quality control,noisy labels might be introduced.Recent research suggests that deep neural networks(DNNs)will overfit noisy labels,leading to the poor performance of the DNNs.To address this challenging problem,we present a Multimodal Robust Meta Learning framework(MRML)for multimodal sentiment analysis to resist noisy labels and correlate distinct modalities simultaneously.Specifically,we propose a two-layer fusion net to deeply fuse different modalities and improve the quality of the multimodal data features for label correction and network training.Besides,a multiple meta-learner(label corrector)strategy is proposed to enhance the label correction approach and prevent models from overfitting to noisy labels.We conducted experiments on three popular multimodal datasets to verify the superiority of ourmethod by comparing it with four baselines.
基金supported by the National Natural Science Foundation of China,No.82271353(to JW)Key Research and Development Program of Liaoning Province,No.2020JH2/10300047(to JF).
文摘LncRNA(long non-coding RNA) H19 is a transcript of the H19 gene that is expressed during embryogenesis.We previously discove red a role for circular lncRNA H19 in the onset and prognosis of cerebral ischemic stroke.In this study,we used serum from patients with ischemic stroke,and mouse and cell culture models to elucidate the roles of plasma and neuronal exosomes in the regulatory effect of lncRNA H19 on insulin-like growth factor-1 and its mechanism in ischemic stroke,using western blotting,quantitative real-time polymerase chain reaction,and enzyme-linked immunosorbent assays.Plasma exosomal IncRNA H19 was negatively associated with blood levels of insulin-like growth factor-1 in samples from patients with cerebral ischemic stroke.In a mouse model,levels of exosomal IncRNA H19 were positively correlated with plasma and cerebral lncRNA H19.In a cell co-culture model,we confirmed that IncRNA H19 was transported from neuro ns to astrocytes by exosomes to induce downregulation of insulin-like growth factor-1 through the H19/let-7 a/insulin-like growth factor-1 receptor axis.This study provides the first evidence for the transpo rtation of IncRNA H19 by exosomes and the relationship between IncRNA H19 and insulinlike growth factor-1.
基金This work was supported in part by the Chongqing Technological Innovation and Application Development Projects under Grant cstc2019jscx-msxm1322,in part by the Zhejiang Lab under Grant 2021KF0AB03in part by the National Natural Science Foundation of China under Grant 62071091.
文摘Network slicing is envisioned as one of the key techniques to meet the extremely diversified service requirements of the Internet of Things(IoT)as it provides an enhanced user experience and elastic resource configuration.In the context of slicing enhanced IoT networks,both the Service Provider(SP)and Infrastructure Provider(InP)face challenges of ensuring efficient slice construction and high profit in dynamic environments.These challenges arise from randomly generated and departed slice requests from end-users,uncertain resource availability,and multidimensional resource allocation.Admission and resource allocation for distinct demands of slice requests are the key issues in addressing these challenges and should be handled effectively in dynamic environments.To this end,we propose an Opportunistic Admission and Resource allocation(OAR)policy to deal with the issues of random slicing requests,uncertain resource availability,and heterogeneous multi-resources.The key idea of OAR is to allow the SP to decide whether to accept slice requests immediately or defer them according to the load and price of resources.To cope with the random slice requests and uncertain resource availability,we formulated this issue as a Markov Decision Process(MDP)to obtain the optimal admission policy,with the aim of maximizing the system reward.Furthermore,the buyer-seller game theory approach was adopted to realize the optimal resource allocation,while motivating each SP and InP to maximize their rewards.Our numerical results show that the proposed OAR policy can make reasonable decisions effectively and steadily,and outperforms the baseline schemes in terms of the system reward.
基金This work was supported in part by the Zhejiang Lab under Grant 20210AB02in part by the Sichuan International Science and Technology Innovation Cooperation/Hong Kong,Macao and Taiwan Science and Technology Innovation Cooperation Project under Grant 2019YFH0163in part by the Key Research and Development Project of Sichuan Provincial Department of Science and Technology under Grant 2018JZ0071.
文摘In order to solve the high latency of traditional cloud computing and the processing capacity limitation of Internet of Things(IoT)users,Multi-access Edge Computing(MEC)migrates computing and storage capabilities from the remote data center to the edge of network,providing users with computation services quickly and directly.In this paper,we investigate the impact of the randomness caused by the movement of the IoT user on decision-making for offloading,where the connection between the IoT user and the MEC servers is uncertain.This uncertainty would be the main obstacle to assign the task accurately.Consequently,if the assigned task cannot match well with the real connection time,a migration(connection time is not enough to process)would be caused.In order to address the impact of this uncertainty,we formulate the offloading decision as an optimization problem considering the transmission,computation and migration.With the help of Stochastic Programming(SP),we use the posteriori recourse to compensate for inaccurate predictions.Meanwhile,in heterogeneous networks,considering multiple candidate MEC servers could be selected simultaneously due to overlapping,we also introduce the Multi-Arm Bandit(MAB)theory for MEC selection.The extensive simulations validate the improvement and effectiveness of the proposed SP-based Multi-arm bandit Method(SMM)for offloading in terms of reward,cost,energy consumption and delay.The results showthat SMMcan achieve about 20%improvement compared with the traditional offloading method that does not consider the randomness,and it also outperforms the existing SP/MAB based method for offloading.
基金This work was supported by the Key Research and Development Project of Jiangsu Province(BE2019009-4)the National Natural Science Foundation of China(52106091)the Qing Lan Project of Jiangsu Province。
文摘Microalgae biomass is an ideal precursor to prepare renewable carbon materials,which has broad application.The bioaccumulation efficiency(lipids,proteins,carbohydrates)and biomass productivity of microalgae are influenced by spectroscopy during the culture process.In this study,a bilayer plate-type photobioreactor was designed to cultivate Chlorella protothecoides with spectral selectivity by nanofluids.Compared to culture without spectral selectivity,the spectral selectivity of Ag/CoSO_(4)nanofluids increased microalgae biomass by 5.76%,and the spectral selectivity of CoSO_(4)solution increased by 17.14%.In addition,the spectral selectivity of Ag/CoSO_(4)nanofluids was more conducive to the accumulation of nutrients(29.46%lipids,50.66%proteins,and 17.86%carbohydrates)in microalgae.Further cultured chlorella was utilized to prepare bioelectrode materials,it was found that algal based biochar had a good pore structure(micro specific surface area:1627.5314 m^(2)/g,average pore size:0.21294 nm).As the current density was 1 A/g,the specific capacitance reached 230 F/g,appearing good electrochemical performance.
基金the National Natural Science Foundation of China under Grant 61701059,Grant 61941114,and Grant 61831002,in part by the Fundamental Research Funds for the Central Universities of New TeachersProject,in part by the Chongqing Technological Innovation and Application Development Projects under Grant cstc2019jscx-msxm1322,and in part by the Eighteentg Open Foundation of State Key Lab of Integrated Services Networks of Xidian University under Grant ISN20-05.
文摘In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no technical analysis and comparison as a guideline to determine which type of consensus mechanism should be adopted in a specific scenario/application.To this end,this work investigates three mainstream consensus mechanisms in the blockchain,namely,Proof of Work(PoW),Proof of Stake(PoS),and Direct Acyclic Graph(DAG),and identifies their performances in terms of the average time to generate a new block,the confirmation delay,the Transaction Per Second(TPS)and the confirmation failure probability.The results show that the consensus process is affected by both network resource(computation power/coin age,buffer size)and network load conditions.In addition,it shows that PoW and PoS are more sensitive to the change of network resource while DAG is more sensitive to network load conditions.
基金supported by the National Key Research and Development Program of China“New Energy Project for Electric Vehicle”(2016YFB0100204)the National Natural Science Foundation of China(Nos.51772030,21805011,51572011,51802012)+2 种基金the Joint Funds of the National Natural Science Foundation of China(U1564206)Beijing Key Research and Development Plan(Z181100004518001)China Postdoctoral Science Foundation(Nos.2017M620637,2018M643697,2019T120930).
文摘MXenes,a new family of two-dimensional(2D)materials with excellent electronic conductivity and hydrophilicity,have shown distinctive advantages as a highly conductive matrix material for lithium-ion battery anodes.Herein,a facile electrostatic self-assembly of SnO2 quantum dots(QDs)on Ti3C2Tx MXene sheets is proposed.The as-prepared SnO2/MXene hybrids have a unique 0D-2D structure,in which the 0D SnO2 QDs(~4.7 nm)are uniformly distributed over 2D Ti3C2Tx MXene sheets with controllable loading amount.The SnO2 QDs serve as a high capacity provider and the“spacer”to prevent the MXene sheets from restacking;the highly conductive Ti3C2Tx MXene can not only provide efficient pathways for fast transport of electrons and Li ions,but also buffer the volume change of SnO2 during lithiation/delithiation by confining SnO2 QDs between the MXene nanosheets.Therefore,the 0D-2D SnO2 QDs/MXene hybrids deliver superior lithium storage properties with high capacity(887.4 mAh g?1 at 50 mA g?1),stable cycle performance(659.8 mAh g?1 at 100 mA g?1 after 100 cycles with a capacity retention of 91%)and excellent rate performance(364 mAh g?1 at 3 A g?1),making it a promising anode material for lithium-ion batteries.
基金supported by the National Natural Science Foundation of China (21805011,51902251,52072021,and U2004212)the State Key Laboratory of Organic-Inorganic Composites (oic-202101010)+1 种基金the Natural Science Foundation of Shaanxi Provincial Department of Education (20JK0753)the Provincial Joint Fund of Shaanxi (2021JLM-28)。
文摘ZnS has great potentials as an anode for lithium storage because of its high theoretical capacity and resource abundance;however,the large volume expansion accompanied with structural collapse and low conductivity of ZnS cause severe capacity fading and inferior rate capability during lithium storage. Herein,0D-2 D ZnS nanodots/Ti_(3)C_(2)T_x MXene hybrids are prepared by anchoring ZnS nanodots on Ti_(3)C_(2)T_(x) MXene nanosheets through coordination modulation between MXene and MOF precursor(ZIF-8) followed with sulfidation. The MXene substratecoupled with the ZnS nanodots can synergistically accommodate volume variation of ZnS over charge–discharge to realize stable cyclability. As revealed by XPS characterizations and DFT calculations,the strong interfacial interaction between ZnS nanodots and MXene nanosheets can boost fast electron/lithium-ion transfer to achieve excellent electrochemical activity and kinetics for lithium storage. Thereby,the as-prepared ZnS nanodots/MXene hybrid exhibits a high capacity of 726.8 mAh g^(-1) at 30 mA g^(-1),superior cyclic stability(462.8 mAh g^(-1) after 1000 cycles at 0.5 A g^(-1)),and excellent rate performance. The present results provide new insights into the understanding of the lithium storage mechanism of ZnS and the revealing of the e ects of interfacial interaction on lithium storage performance enhancement.
基金This work was supported in part by the U.K.EPSRC(EP/S02476X/1)Sichuan International Science and Technology Innovation Cooperation/Hong Kong,Macao and Taiwan Science and Technology Innovation Cooperation Project(2019YFH0163)Key Research and Development Project of Sichuan Provincial Department of Science and Technology(2018JZ0071).
文摘The sixth-generation(6G)network must provide better performance than previous generations to meet the requirements of emerging services and applications,such as multi-gigabit transmission rate,higher reliability,and sub-1 ms latency and ubiquitous connection for the Internet of Everything(IoE).However,with the scarcity of spectrum resources,efficient resource management and sharing are crucial to achieving all these ambitious requirements.One possible technology to achieve all this is the blockchain.Because of its inherent properties,the blockchain has recently gained an important position,which is of great significance to the 6G network and other networks.In particular,the integration of the blockchain in 6G will enable the network to monitor and manage resource utilization and sharing efficiently.Hence,in this paper,we discuss the potentials of the blockchain for resource management and sharing in 6G using multiple application scenarios,namely,Internet of things,deviceto-device communications,network slicing,and inter-domain blockchain ecosystems.
基金This work was supported in part by the National Natural Science Foundation of China under Grant 61701059,Grant 61941114,and Grant 61831002in part by the Fundamental Research Funds for the Central Universities of New Teachers Project,in part by the Basic and Advanced Research Projects of CSTC(No.cstc2019jcyj-zdxmX0008)+2 种基金in part by the Chongqing Science and Technology Innovation Leading Talent Support Program(CSTCCXLJR-C201710,and CSTCCXLJRC201908)in part by Chongqing Technological Innovation and Application Development Projects(cstc2019jscx-msxm1322)in part by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K201900605).
文摘The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performance analysis,most of them only address the intentional forking caused by a malicious attacker.In fact,without any attacker,unintentional forking still remains due to transmission delay and failure,especially in wireless network scenarios.To this end,this paper investigates the reason for generating unintentional forking and derives the forking probability expression in Wireless Blockchain Networks(WBN).Furthermore,in order to illustrate the unintentional forking on the blockchain system,the performances in terms of resource utilization rate,block generation time,and Transaction Per Second(TPS)are investigated.The numerical results show that the target difficulty of hash algorithm in generating a new block,the delay time of broadcasting,the network scale,and the transmission failure probability would affect the unintentional forking probability significantly,which can provide a reliable basis for avoiding forking to save resource consumption and improving system performance.
基金the Scientific Research Foundation of Sichuan Provincial Education Department(11ZA065:Scleral TGF-b1 expression in guinea pigs with form-deprivation myopia is altered in response to invigoration spleen and elimination blood stasis)the Department of Public Health Foundation,Sichuan Province(110527:Study on FDM guinea pig scleral fibroblasts TGFb1/Smad3 signaling pathway)the Science and Technology Development Foundation of the Teaching Hospital of Chengdu University of TCM(2012-D-YY-12:Research on FDM:guinea pig retinal function is altered in response to nourishing Xu and removing blood stasis).
文摘Objective:To explore whether the traditional Chinese medicine(TCM)Bu Jing Yi Shi Tablets alters the expression of scleral TGF-b1 and Smad3 in guinea pigs with formdeprivation myopia(FDM).Methods:Sixty-five guinea pigs were randomly divided into control,model,low-,medium-,and high-dose treatment groups.Except for the control group,FDM was induced by covering the right eye of each animal with opaque latex.The treatment groups were gavaged with different suspension concentrations of Bu Jing Yi Shi Tablets.Refraction and axial length were performed before and after myopia induction.At the end of the experiment,all right eyes were extracted,and scleral sections were prepared for staining and TGF-b1 and Smad3 immunohistochemistry.Scleral thickness and area,the scleral fibroblast quantity,and scleral TGFb1 and Smad3 expressions were measured.Results:The 5 FDM groups had the same initial axial length and diopter,the final diopter and axial length of the model group were significantly increased compared with the control group and treatment groups(P<.01).The axial length of each treatment group decreased as the dose decreased compared with the model group(P<.01);the total scleral area(P<.05 e.01)and the number of scleral fibroblasts(P<.01)in the model group were significantly lower than the treatment groups.Both the TGF-b1 and Smad3 integral optical densities in the model group were significantly lower than the control and medium-and high-dose treatment groups(P<.01).TGF-b1 and Smad3 mRNAs in the model group were decreased compared with the control group,but increased in expression after treatment.
文摘Mobile edge caching technology is gaining more and more attention because it can effectively improve the Quality of Experience (QoE) of users and reduce backhaul burden. This paper aims to improve the utility of mobile edge caching technology from the perspectie of caching resource management by examining a network composed of one operator, multiple users and Content Providers (CPs). The caching resource management model is constructed on the premise of fully considering the QoE of users and the servicing capability of the Base Station (BS). In order to create the best caching resource allocation scheme, the original problem is transformed into a multi-leader multi-follower Stackelberg game model through the analysis of the system model. The strategy combinations and the utility functions of players are analyzed. The existence and uniqueness of the Nash Equilibrium (NE) solution are also analyzed and proved. The optimal strategy combinations and the best responses are deduced in detail. Simulation results and analysis show that the proposed model and algorithm can achieve the optimal allocation of caching resource and improve the QoE of users.
基金supported by the National Key Research and Development Program of China(Nos.2017YFE0301100 and 2017YFA0402500)National Natural Science Foundation of China(No.11605237)the Users with Excellence Program of Hefei Science Center CAS(2020HSC-UE010)。
文摘The steady fusion plasma operation is constrained by tungsten(W)material sputtering issue in the EAST tokamak.In this work,the suppression of W sputtering source has been studied by advanced wall conditionings.It is also concluded that the W sputtering yield becomes more with increasing carbon(C)content in the main deuterium(D)plasma.In EAST,the integrated use of discharge cleanings and lithium(Li)coating has positive effects on the suppression of W sputtering source.In the plasma recovery experiments,it is suggested that the W intensity is reduced by approximately 60%with the help of~35 h Ion Cyclotron Radio Frequency Discharge Cleaning(ICRF-DC)and~40 g Li coating after vacuum failure.The first wall covered by Li film could be relieved from the bombardment of energetic particles,and the impurity in the vessel would be removed through the particle induced desorption and isotope exchange during the discharge cleanings.In general,the sputtering yield of W would decrease from the source,on the bias of the improvement of wall condition and the mitigation of plasmawall interaction process.It lays important base of the achievement of high-parameter and longpulse plasma operation in EAST.The experiences also would be constructive for us to promote the understanding of relevant physics and basis towards the ITER-like condition.
基金This work is supported by China Postdoctoral Science Foundation(2021M690798)Guizhou Province Science and Technology Plan Project(No.[2021]General 085)+1 种基金National Natural Science Foundation of China(No.61603034)the Fundamental Research Funds for the Central Universities(Nos.FRF-BD-19-002A,FRF-DF-20-14).
文摘With the increasing demand for petroleum resources and environmental issues,new energy electric vehicles are increasingly being used.However,the large number of electric vehicles connected to the grid has brought new challenges to the operation of the grid.Firstly,A novel bidirectional interaction model is established based on modulation theory with nonlinear loads.Then,the electric energy measuring scheme of EVs for V2G is derived under the conditions of distorted power loads.The scheme is composed of fundamental electric energy,fundamental-distorted electric energy,distorted-fundamental electric energy and distorted electric energy.And the characteristics of each electric energy are analyzed.Finally,the correctness of the model and energy measurement method is verified by three simulation cases:the impact signals,the fluctuating signals,and the harmonic signals.
基金supported by the Chinese Academy of Sciences Key Research Program (No. KZZD-EW-13)the Natural Science Foundation of China (Nos. 91025013, 91325202)+1 种基金the State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZY-06), CASthe Major Research Plan of the National Natural Science Foundation of China (No. 2013CBA01802)
文摘Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating spring, summer, autumn and winter air temperatures and mean annual air temperature(MAAT) from 1960 through 2008 over the Heihe River Basin reveals a statistically significant trend of 0.31 °C/decade, 0.28 °C/decade, 0.37 °C/decade, 0.50 °C/decade, and 0.37 °C /decade, respectively. The averaged time series of mean annual ground surface temperature(MAGST) and maximum annual ground surface temperature(MaxAGST) for 1972–2006 over the basin indicates a statistically significant trend of 0.58 °C/decade and 1.27 °C/decade, respectively. The minimum annual ground surface temperature(MinAGST) in the same period remains unchanged as a whole. Estimating surface freezing/thawing index as well as the ratio of freezing index to thawing index(RFT) in the period between 1959 and 2006 over the basin indicates a statistically significant trend of-42.5 °C-day/decade, 85.4 °C-day/decade and-0.018/decade, respectively.
