In this paper,to deal with the heterogeneity in federated learning(FL)systems,a knowledge distillation(KD)driven training framework for FL is proposed,where each user can select its neural network model on demand and ...In this paper,to deal with the heterogeneity in federated learning(FL)systems,a knowledge distillation(KD)driven training framework for FL is proposed,where each user can select its neural network model on demand and distill knowledge from a big teacher model using its own private dataset.To overcome the challenge of train the big teacher model in resource limited user devices,the digital twin(DT)is exploit in the way that the teacher model can be trained at DT located in the server with enough computing resources.Then,during model distillation,each user can update the parameters of its model at either the physical entity or the digital agent.The joint problem of model selection and training offloading and resource allocation for users is formulated as a mixed integer programming(MIP)problem.To solve the problem,Q-learning and optimization are jointly used,where Q-learning selects models for users and determines whether to train locally or on the server,and optimization is used to allocate resources for users based on the output of Q-learning.Simulation results show the proposed DT-assisted KD framework and joint optimization method can significantly improve the average accuracy of users while reducing the total delay.展开更多
Heterogeneous networks （HetNets） composed of overlapped cells with different sizes are expected to improve the transmission performance of data service significantly. User equipments （UEs） in the overlapped area o...Heterogeneous networks （HetNets） composed of overlapped cells with different sizes are expected to improve the transmission performance of data service significantly. User equipments （UEs） in the overlapped area of multiple cells might be able to access various base stations （BSs） of the cells, resulting in various transmission performances due to cell heterogeneity. Hence, designing optimal cell selection scheme is of particular importance for it may affect user quality of service （QoS） and network performance significantly. In this paper, we jointly consider cell selection and transmit power allocation problem in a HetNet consisting of multiple cells. For a single UE case, we formulate the energy efficiency of the UE, and propose an energy efficient optimization scheme which selects the optimal cell corresponding to the maximum energy efficiency of the UE. The problem is then extended to multiple UEs case. To achieve joint performance optimization of all the UEs, we formulate an optimization problem with the objective of maximizing the sum energy efficiency of UEs subject to QoS and power constraints. The formulated nonlinear fractional optimization problem is equivalently transformed into two subproblems, i.e., power allocation subproblem of each UE-eell pair, and cell selection subproblem of UEs. The two subproblems are solved respectively through applying Lagrange dual method and Kuhn-Munkres （K- M） algorithm. Numerical results demonstrate the efficiency of the proposed algorithm.展开更多
Cognitive radio networks(CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users(SUs) to opportunistically access the licensed spectrum of primary users(PUs).In CRNs,source and desti...Cognitive radio networks(CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users(SUs) to opportunistically access the licensed spectrum of primary users(PUs).In CRNs,source and destination SUs may achieve information interaction in an ad hoc manner.In the case that no direct transmission link between the SU transmission pairs is available,multi-hop relay SUs can be applied to forward information for the source and destination SUs,resulting in multi-hop CRNs.In this paper,we consider a multi-hop CRN consisting of multiple PUs,SU transmission pairs and relay SUs.Stressing the importance of transmission hops and the tradeoff between data rate and power consumption,we propose an energy efficient constrained shortest path first(CSPF)-based joint resource allocation and route selection algorithm,which consists of two sub-algorithms,i.e.,CSPF-based route selection sub-algorithm and energy efficient resource allocation sub-algorithm.More specifically,we first apply CSPF-based route selection sub-algorithm to obtain the shortest candidate routes(SCRs) between the SU pair under the transmission constraints.Then,an energy efficient resource allocation problem of the SCRs is formulated and solved by applying iterative algorithm and Lagrange dual method.Simu-lation results demonstrate the effectiveness of the proposed algorithm.展开更多
BACKGROUND Pulp revascularization is a novel way to treat immature teeth with periapical disease,and the technique has become increasingly well established in recent years.By puncturing the periapical tissue,bleeding ...BACKGROUND Pulp revascularization is a novel way to treat immature teeth with periapical disease,and the technique has become increasingly well established in recent years.By puncturing the periapical tissue,bleeding is induced,and a blood clot is formed in the root canal.The blood clot acts as a natural bioscaffold onto which mesenchymal stem cells from periapical tissue can be seeded and restore pulp vascularity,thus promoting root development as well as apical closure.Although the effect of pulp revascularization is ideal,there are certain requirements for the apical condition of the teeth.The apical barrier technique and apexification are still indispensable for teeth that cannot achieve ideal blood clot formation.In addition,a meta-analysis of several clinical studies concluded that pulp revascu-larization has no significant advantages over other treatments.CASE SUMMARY A 10-year-old girl complained of pain in the right upper and lower posterior teeth for 2 d.Clinical and radiological examinations revealed that both the right maxillary and mandibular second premolars were immature with periapical radiolucency.The right maxillary second premolar was treated by pulp revascu-larization,while the right mandibular second premolar was treated by conven-tional apical barrier surgery after revascularization failed.The purpose of this report is to compare the different root maturation processes induced by the pulp revascularization and apical barrier techniques in the same patient in homonymous teeth from different jaws.Twelve months of follow-up showed that the apical foramen of both teeth presented a clear tendency to close;however,the tooth treated with pulp revascularization showed a significant increase in root length as well as root canal wall thickness.CONCLUSION For the treatment of nonvital immature teeth,pulp revascularization showed a superior therapeutic effect in comparison with the apical barrier technique.展开更多
Forming electrostatic nanocomplexes(ENCs)with counter-ions can improve the delivery efficiency of chemotherapy drugs.However,water-soluble chemotherapy drugs like mitoxantrone(MTO),have limited affinity for counter-io...Forming electrostatic nanocomplexes(ENCs)with counter-ions can improve the delivery efficiency of chemotherapy drugs.However,water-soluble chemotherapy drugs like mitoxantrone(MTO),have limited affinity for counter-ions,posing challenges in the creation of stable ENCs.Herein,MTO was connected to fatty alcohols of varying chain lengths(C8,C12,C16)via disulfide bonds,forming hydrophobic prodrugs.We found that conjugating MTO to fatty alcohols significantly improved its affinity for the counter-ion sodium cholesterol sulfate(SCS).Among the designed prodrugs,conjugated to fatty alcohols with longer carbon chain lengths exhibited heightened affinity for SCS,resulting in the formation of more stable ENCs.However,extending the carbon chain also slowed the rate of drug release.Overall,compared with MTO solution,these ENCs demonstrated comparable therapeutic efficacy while causing minimal damage to healthy tissues,especially for MTO-SS-C16 ENCs.Our research provides new insights for constructing stable and safe ENCs for hydrophilic drugs like MTO.展开更多
Irinotecan,one of the most effective chemotherapeutic agents for the treatment of advanced colorectal cancer,suffers from extremely low activatability and non-selective tumor activation.7-Ethyl-10-hydroxy-camptothecin...Irinotecan,one of the most effective chemotherapeutic agents for the treatment of advanced colorectal cancer,suffers from extremely low activatability and non-selective tumor activation.7-Ethyl-10-hydroxy-camptothecin(SN38),the active metabolite of irinotecan,has been limited in clinical development due to poor water solubility and stability.Here,the thioether bond and disulfide bond were employed as response modules to construct tumor-selective SN38 prodrug nanoassemblies(SN38-S-C_(21) NPs and SN38-SS-C_(21) NPs).11-Henicosanol was chosen as a self-assembly module to enhance stability.Both SN38-S-C_(21) NPs and SN38-SS-C_(21) NPs presented ultra-high in vivo stability with a 12146-fold and 23151-fold elevation in the area under the curve(AUC)compared to SN38.Moreover,SN38-S-C_(21) NPs and SN38-SS-C_(21) NPs showed a significant reduction of SN38exposure in blood compared to irinotecan.Importantly,the prodrug nanoassemblies enabled selective activation within tumor cells,and the conversion rates of SN38-SS-C_(21) NPs and SN38-S-C_(21) NPs to SN38 were 10-and 7-fold higher than irinotecan.Compared with SN38-S-C_(21) NPs,the superior in vivo stability,SN38 conversion efficiency and tumor selectivity of SN38-SSC_(21) NPs resulted in potent antitumor effects and safety.Our findings proved that the disulfide bond was more suitable for constructing high-performance SN38 prodrug nanoassemblies,which showed significant promise for the rational design of SN38 nanomedicines.展开更多
The local hypoxic tumor environment substantially hampers the therapeutic efficiency of radiotherapy, which typically requires the large X-ray doses for tumor treatment but induces the serious side effects. Herein, a ...The local hypoxic tumor environment substantially hampers the therapeutic efficiency of radiotherapy, which typically requires the large X-ray doses for tumor treatment but induces the serious side effects. Herein, a bio-mimetic radiosensitized platform based on a natural in-situ oxygen-evolving photosynthetic cyanobacteria combined with two-dimensional (2D) bismuthene with high atomic-number (Z) components, is designed and engineered to effectively modulate the radiotherapy-resistant hypoxic tumor environment and achieve sufficient radiation energy deposition into tumor. Upon the exogenous sequential irradiation of 660 nm laser and X-ray beam, continuous photosynthetic oxygen evolution by the cyanobacteria and considerable generation of reactive oxygen species by the 2D bismuthene radiosensitizer substantially augmented the therapeutic efficacy of radiotherapy and suppressed the in vivo tumor growth, as demonstrated on both LLC-lung tumor xenograft-bearing C57/B6 mice model and 4T1-breast tumor xenograft-bearing Balb/c mice model, further demon-strating the photosynthetic hypoxia-alleviation capability and radiosensitization performance of the engineered biomimetic radiosensitized platform. This work exemplifies a distinct paradigm on the construction of microorganism-enabled tumor-microenvironment modulation and nanoradiosensitizer-augmented radiotherapy for efficient tumor treatment.展开更多
The Late Triassic witnessed significant collisional orogenic events in the Qinling orogenic belt,accompanied by magma underplating and tectonic deformation.These processes potentially resulted in substantial crustal t...The Late Triassic witnessed significant collisional orogenic events in the Qinling orogenic belt,accompanied by magma underplating and tectonic deformation.These processes potentially resulted in substantial crustal thickening and uplift of the Qinling orogen.However,due to the absence of igneous rock records from this period in the eastern section of the Qinling orogen,the changes in crustal thickness during this orogenic process have not been thoroughly investigated.A series of foreland basins emerged during the Early Mesozoic to the south of the East Qinling orogenic belt.These basins have preserved clastic sedimentary rocks derived from the uplift and erosion of the orogenic belt.These sedimentary records serve as crucial records to reconstruct the evolutionary history of the Qinling orogen.To further clarify the collisional orogenic process of the Qinling orogenic belt,this study conducted in situ volcanic lithic fragment geochemistry,detrital zircon U-Pb chronology and trace element composition analysis on the sandstones of the Lower Jurassic Tongzhuyuan Formation in the Zigui Basin.The results suggest that the sandstones,which exhibit a significant abundance of volcanic lithic fragments,has a characteristic detrital zircon age group of 250–200 Ma,indicating a major provenance from the Triassic volcanic rocks.Combined with regional correlation and paleocurrent analysis,the detrital zircon U-Pb age data show that the source area of volcanic rocks should be in the Qinling orogenic belt to the north of the basin.This interpretation is further supported by the Triassic granitic rocks exposed in the western part of the orogenic belt,representing the magmatism during the Triassic collisional orogenesis in the Qinling orogen.Based on the co-varying relationships between present-day crust thickness with the chemical compositions of granite rocks and zircons,the La/Yb ratio of volcanic lithic fragments in the Tongzhuyuan Formation and the Eu/Eu*ratio of detrital zircons with Triassic ages indicate that the Qinling orogen experienced crustal thickening during the Late Triassic,reaching its maximum thickness of 60–70 km at ca.220–210 Ma.This crustal thickening in the eastern Qinling orogen is temporally consistent with that in the western orogen as recorded by the Triassic granitic rocks and may be related to large-scale crustal shortening and magmatism during the collisional orogeny.展开更多
Task offloading is a potential solution to satisfy the strict requirements of computation-intensive and latency-sensitive vehicular applications due to the limited onboard computing resources.However,the overwhelming ...Task offloading is a potential solution to satisfy the strict requirements of computation-intensive and latency-sensitive vehicular applications due to the limited onboard computing resources.However,the overwhelming upload traffic may lead to unacceptable uploading time.To tackle this issue,for tasks taking environmental data as input,the data perceived by roadside units(RSU)equipped with several sensors can be directly exploited for computation,resulting in a novel task offloading paradigm with integrated communications,sensing and computing(I-CSC).With this paradigm,vehicles can select to upload their sensed data to RSUs or transmit computing instructions to RSUs during the offloading.By optimizing the computation mode and network resources,in this paper,we investigate an I-CSC-based task offloading problem to reduce the cost caused by resource consumption while guaranteeing the latency of each task.Although this nonconvex problem can be handled by the alternating minimization(AM)algorithm that alternatively minimizes the divided four sub-problems,it leads to high computational complexity and local optimal solution.To tackle this challenge,we propose a creative structural knowledge-driven meta-learning(SKDML)method,involving both the model-based AM algorithm and neural networks.Specifically,borrowing the iterative structure of the AM algorithm,also referred to as structural knowledge,the proposed SKDML adopts long short-term memory(LSTM)networkbased meta-learning to learn an adaptive optimizer for updating variables in each sub-problem,instead of the handcrafted counterpart in the AM algorithm.Furthermore,to pull out the solution from the local optimum,our proposed SKDML updates parameters in LSTM with the global loss function.Simulation results demonstrate that our method outperforms both the AM algorithm and the meta-learning without structural knowledge in terms of both the online processing time and the network performance.展开更多
基金supported by the National Key Research and Development Program of China (2020YFB1807700)the National Natural Science Foundation of China (NSFC)under Grant No.62071356the Chongqing Key Laboratory of Mobile Communications Technology under Grant cqupt-mct202202。
文摘In this paper,to deal with the heterogeneity in federated learning(FL)systems,a knowledge distillation(KD)driven training framework for FL is proposed,where each user can select its neural network model on demand and distill knowledge from a big teacher model using its own private dataset.To overcome the challenge of train the big teacher model in resource limited user devices,the digital twin(DT)is exploit in the way that the teacher model can be trained at DT located in the server with enough computing resources.Then,during model distillation,each user can update the parameters of its model at either the physical entity or the digital agent.The joint problem of model selection and training offloading and resource allocation for users is formulated as a mixed integer programming(MIP)problem.To solve the problem,Q-learning and optimization are jointly used,where Q-learning selects models for users and determines whether to train locally or on the server,and optimization is used to allocate resources for users based on the output of Q-learning.Simulation results show the proposed DT-assisted KD framework and joint optimization method can significantly improve the average accuracy of users while reducing the total delay.
文摘Heterogeneous networks （HetNets） composed of overlapped cells with different sizes are expected to improve the transmission performance of data service significantly. User equipments （UEs） in the overlapped area of multiple cells might be able to access various base stations （BSs） of the cells, resulting in various transmission performances due to cell heterogeneity. Hence, designing optimal cell selection scheme is of particular importance for it may affect user quality of service （QoS） and network performance significantly. In this paper, we jointly consider cell selection and transmit power allocation problem in a HetNet consisting of multiple cells. For a single UE case, we formulate the energy efficiency of the UE, and propose an energy efficient optimization scheme which selects the optimal cell corresponding to the maximum energy efficiency of the UE. The problem is then extended to multiple UEs case. To achieve joint performance optimization of all the UEs, we formulate an optimization problem with the objective of maximizing the sum energy efficiency of UEs subject to QoS and power constraints. The formulated nonlinear fractional optimization problem is equivalently transformed into two subproblems, i.e., power allocation subproblem of each UE-eell pair, and cell selection subproblem of UEs. The two subproblems are solved respectively through applying Lagrange dual method and Kuhn-Munkres （K- M） algorithm. Numerical results demonstrate the efficiency of the proposed algorithm.
基金supported by the National Science and Technology Specific Project of China(2016ZX03001010-004)National Natural Science Foundation of China(6140105361571073)+2 种基金the Joint Scientifi c Research Fund Ministry of Education and China Mobile(MCM20160105)the special fund of Chongqing key laboratory(CSTC)the project of Chongqing Municipal Education Commission(Kjzh11206)
文摘Cognitive radio networks(CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users(SUs) to opportunistically access the licensed spectrum of primary users(PUs).In CRNs,source and destination SUs may achieve information interaction in an ad hoc manner.In the case that no direct transmission link between the SU transmission pairs is available,multi-hop relay SUs can be applied to forward information for the source and destination SUs,resulting in multi-hop CRNs.In this paper,we consider a multi-hop CRN consisting of multiple PUs,SU transmission pairs and relay SUs.Stressing the importance of transmission hops and the tradeoff between data rate and power consumption,we propose an energy efficient constrained shortest path first(CSPF)-based joint resource allocation and route selection algorithm,which consists of two sub-algorithms,i.e.,CSPF-based route selection sub-algorithm and energy efficient resource allocation sub-algorithm.More specifically,we first apply CSPF-based route selection sub-algorithm to obtain the shortest candidate routes(SCRs) between the SU pair under the transmission constraints.Then,an energy efficient resource allocation problem of the SCRs is formulated and solved by applying iterative algorithm and Lagrange dual method.Simu-lation results demonstrate the effectiveness of the proposed algorithm.
基金Supported by The Natural Science Foundation of Shaanxi Province,China,No.2022JM-447.
文摘BACKGROUND Pulp revascularization is a novel way to treat immature teeth with periapical disease,and the technique has become increasingly well established in recent years.By puncturing the periapical tissue,bleeding is induced,and a blood clot is formed in the root canal.The blood clot acts as a natural bioscaffold onto which mesenchymal stem cells from periapical tissue can be seeded and restore pulp vascularity,thus promoting root development as well as apical closure.Although the effect of pulp revascularization is ideal,there are certain requirements for the apical condition of the teeth.The apical barrier technique and apexification are still indispensable for teeth that cannot achieve ideal blood clot formation.In addition,a meta-analysis of several clinical studies concluded that pulp revascu-larization has no significant advantages over other treatments.CASE SUMMARY A 10-year-old girl complained of pain in the right upper and lower posterior teeth for 2 d.Clinical and radiological examinations revealed that both the right maxillary and mandibular second premolars were immature with periapical radiolucency.The right maxillary second premolar was treated by pulp revascu-larization,while the right mandibular second premolar was treated by conven-tional apical barrier surgery after revascularization failed.The purpose of this report is to compare the different root maturation processes induced by the pulp revascularization and apical barrier techniques in the same patient in homonymous teeth from different jaws.Twelve months of follow-up showed that the apical foramen of both teeth presented a clear tendency to close;however,the tooth treated with pulp revascularization showed a significant increase in root length as well as root canal wall thickness.CONCLUSION For the treatment of nonvital immature teeth,pulp revascularization showed a superior therapeutic effect in comparison with the apical barrier technique.
基金financial support from National Natural Science Foundation of China (82272151,82173766,and 82204318)Liaoning Revitalization Talents Program (XLYC2203083)Shenyang Young and Middle-aged Science and Technology Innovation Talent Support Program (RC220389)。
文摘Forming electrostatic nanocomplexes(ENCs)with counter-ions can improve the delivery efficiency of chemotherapy drugs.However,water-soluble chemotherapy drugs like mitoxantrone(MTO),have limited affinity for counter-ions,posing challenges in the creation of stable ENCs.Herein,MTO was connected to fatty alcohols of varying chain lengths(C8,C12,C16)via disulfide bonds,forming hydrophobic prodrugs.We found that conjugating MTO to fatty alcohols significantly improved its affinity for the counter-ion sodium cholesterol sulfate(SCS).Among the designed prodrugs,conjugated to fatty alcohols with longer carbon chain lengths exhibited heightened affinity for SCS,resulting in the formation of more stable ENCs.However,extending the carbon chain also slowed the rate of drug release.Overall,compared with MTO solution,these ENCs demonstrated comparable therapeutic efficacy while causing minimal damage to healthy tissues,especially for MTO-SS-C16 ENCs.Our research provides new insights for constructing stable and safe ENCs for hydrophilic drugs like MTO.
基金supported by the National Key R&D Program of China(2022YFE0111600)the Key Research and Development Program of Liaoning Province(2024JH2/102500061)+7 种基金the Youth Innovation Team of Liaoning Provincial Department of Education(LJ222410163049)the Liaoning Revitalization Talents Program(XLYC2203083)the Open Fund of High-level Key Discipline of Chemistry of Chinese Medicine of the State Administration of Traditional Chinese Medicinethe Anhui University of Chinese Medicine(HKDCCM2024007)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)(GZC20231-732)the China Postdoctoral Science Foundation(2023TQ0222,2023MD744229)the General Program of Department of Education of Liaoning Province(JYTMS20231372)the Doctoral Scientific Research Staring Foundation of Liaoning Province(2024-BS-073)。
文摘Irinotecan,one of the most effective chemotherapeutic agents for the treatment of advanced colorectal cancer,suffers from extremely low activatability and non-selective tumor activation.7-Ethyl-10-hydroxy-camptothecin(SN38),the active metabolite of irinotecan,has been limited in clinical development due to poor water solubility and stability.Here,the thioether bond and disulfide bond were employed as response modules to construct tumor-selective SN38 prodrug nanoassemblies(SN38-S-C_(21) NPs and SN38-SS-C_(21) NPs).11-Henicosanol was chosen as a self-assembly module to enhance stability.Both SN38-S-C_(21) NPs and SN38-SS-C_(21) NPs presented ultra-high in vivo stability with a 12146-fold and 23151-fold elevation in the area under the curve(AUC)compared to SN38.Moreover,SN38-S-C_(21) NPs and SN38-SS-C_(21) NPs showed a significant reduction of SN38exposure in blood compared to irinotecan.Importantly,the prodrug nanoassemblies enabled selective activation within tumor cells,and the conversion rates of SN38-SS-C_(21) NPs and SN38-S-C_(21) NPs to SN38 were 10-and 7-fold higher than irinotecan.Compared with SN38-S-C_(21) NPs,the superior in vivo stability,SN38 conversion efficiency and tumor selectivity of SN38-SSC_(21) NPs resulted in potent antitumor effects and safety.Our findings proved that the disulfide bond was more suitable for constructing high-performance SN38 prodrug nanoassemblies,which showed significant promise for the rational design of SN38 nanomedicines.
基金The authors greatly acknowledge the financial support from the National Natural Science Foundation of China(Grant Nos.81703021,81772604)Basic Research Program of Shanghai Municipal Government(Grant No.21JC1406002)+2 种基金Shanghai Science and Technology Program(Grant No.21010500100)Youth Program of National Natural Science Foundation of China(Grant No.51902334)Shanghai Pujiang Program(2020PJD56).
文摘The local hypoxic tumor environment substantially hampers the therapeutic efficiency of radiotherapy, which typically requires the large X-ray doses for tumor treatment but induces the serious side effects. Herein, a bio-mimetic radiosensitized platform based on a natural in-situ oxygen-evolving photosynthetic cyanobacteria combined with two-dimensional (2D) bismuthene with high atomic-number (Z) components, is designed and engineered to effectively modulate the radiotherapy-resistant hypoxic tumor environment and achieve sufficient radiation energy deposition into tumor. Upon the exogenous sequential irradiation of 660 nm laser and X-ray beam, continuous photosynthetic oxygen evolution by the cyanobacteria and considerable generation of reactive oxygen species by the 2D bismuthene radiosensitizer substantially augmented the therapeutic efficacy of radiotherapy and suppressed the in vivo tumor growth, as demonstrated on both LLC-lung tumor xenograft-bearing C57/B6 mice model and 4T1-breast tumor xenograft-bearing Balb/c mice model, further demon-strating the photosynthetic hypoxia-alleviation capability and radiosensitization performance of the engineered biomimetic radiosensitized platform. This work exemplifies a distinct paradigm on the construction of microorganism-enabled tumor-microenvironment modulation and nanoradiosensitizer-augmented radiotherapy for efficient tumor treatment.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41888101,42102121,42122015)the China Geological Survey Project(Grant Nos.DD20230008,DD20221656)Guizhou Provincial Science and Technology Projects(Grant No.ZK[2022]General 081).
文摘The Late Triassic witnessed significant collisional orogenic events in the Qinling orogenic belt,accompanied by magma underplating and tectonic deformation.These processes potentially resulted in substantial crustal thickening and uplift of the Qinling orogen.However,due to the absence of igneous rock records from this period in the eastern section of the Qinling orogen,the changes in crustal thickness during this orogenic process have not been thoroughly investigated.A series of foreland basins emerged during the Early Mesozoic to the south of the East Qinling orogenic belt.These basins have preserved clastic sedimentary rocks derived from the uplift and erosion of the orogenic belt.These sedimentary records serve as crucial records to reconstruct the evolutionary history of the Qinling orogen.To further clarify the collisional orogenic process of the Qinling orogenic belt,this study conducted in situ volcanic lithic fragment geochemistry,detrital zircon U-Pb chronology and trace element composition analysis on the sandstones of the Lower Jurassic Tongzhuyuan Formation in the Zigui Basin.The results suggest that the sandstones,which exhibit a significant abundance of volcanic lithic fragments,has a characteristic detrital zircon age group of 250–200 Ma,indicating a major provenance from the Triassic volcanic rocks.Combined with regional correlation and paleocurrent analysis,the detrital zircon U-Pb age data show that the source area of volcanic rocks should be in the Qinling orogenic belt to the north of the basin.This interpretation is further supported by the Triassic granitic rocks exposed in the western part of the orogenic belt,representing the magmatism during the Triassic collisional orogenesis in the Qinling orogen.Based on the co-varying relationships between present-day crust thickness with the chemical compositions of granite rocks and zircons,the La/Yb ratio of volcanic lithic fragments in the Tongzhuyuan Formation and the Eu/Eu*ratio of detrital zircons with Triassic ages indicate that the Qinling orogen experienced crustal thickening during the Late Triassic,reaching its maximum thickness of 60–70 km at ca.220–210 Ma.This crustal thickening in the eastern Qinling orogen is temporally consistent with that in the western orogen as recorded by the Triassic granitic rocks and may be related to large-scale crustal shortening and magmatism during the collisional orogeny.
基金supported in part by National Key Research and Development Program of China(2020YFB1807700)in part by National Natural Science Foundation of China(62201414)+2 种基金in part by Qinchuangyuan Project(OCYRCXM-2022-362)in part by Science and Technology Project of Guangzhou(2023A04J1741)in part by Chongqing key laboratory of Mobile Communications Technologg(cqupt-mct-202202).
文摘Task offloading is a potential solution to satisfy the strict requirements of computation-intensive and latency-sensitive vehicular applications due to the limited onboard computing resources.However,the overwhelming upload traffic may lead to unacceptable uploading time.To tackle this issue,for tasks taking environmental data as input,the data perceived by roadside units(RSU)equipped with several sensors can be directly exploited for computation,resulting in a novel task offloading paradigm with integrated communications,sensing and computing(I-CSC).With this paradigm,vehicles can select to upload their sensed data to RSUs or transmit computing instructions to RSUs during the offloading.By optimizing the computation mode and network resources,in this paper,we investigate an I-CSC-based task offloading problem to reduce the cost caused by resource consumption while guaranteeing the latency of each task.Although this nonconvex problem can be handled by the alternating minimization(AM)algorithm that alternatively minimizes the divided four sub-problems,it leads to high computational complexity and local optimal solution.To tackle this challenge,we propose a creative structural knowledge-driven meta-learning(SKDML)method,involving both the model-based AM algorithm and neural networks.Specifically,borrowing the iterative structure of the AM algorithm,also referred to as structural knowledge,the proposed SKDML adopts long short-term memory(LSTM)networkbased meta-learning to learn an adaptive optimizer for updating variables in each sub-problem,instead of the handcrafted counterpart in the AM algorithm.Furthermore,to pull out the solution from the local optimum,our proposed SKDML updates parameters in LSTM with the global loss function.Simulation results demonstrate that our method outperforms both the AM algorithm and the meta-learning without structural knowledge in terms of both the online processing time and the network performance.
