Anumber of research papers including several review papers have reported that autonomous vehicles(AVs)consume a significant amount of power to run the onboard computers that do all the calculations needed to process a...Anumber of research papers including several review papers have reported that autonomous vehicles(AVs)consume a significant amount of power to run the onboard computers that do all the calculations needed to process and analyze the sig-nificant amount of data.In addition,there is a substantial amount of power consumption by onboard sensors including radars,cam-eras,Lidars,etc.[1]The resulting power consumption results in range reduction in electric autonomous vehicles.This in-turn increases the emissions based on how the electricity is obtained for charging these vehicle batteries.As the degree of automation moves up the ladder of AVs,the complexity of the overall control,management,and the associated tasks grow exponentially,and hence increasing the power consumption.The Society of Auto-motive Engineers(SAE)defines 6 levels of driving automation ranging from Level 0(fully manual)to Level 5(fully autonomous).Level 0 is no driving automation and the driver is responsible for full control of the vehicle.Level 1 is the driver assisted by a support system like adaptive cruise control or lane-changing assistance,but the driver must remain engaged.In Level 2.展开更多
In recent years,the exponential proliferation of smart devices with their intelligent applications poses severe challenges on conventional cellular networks.Such challenges can be potentially overcome by integrating c...In recent years,the exponential proliferation of smart devices with their intelligent applications poses severe challenges on conventional cellular networks.Such challenges can be potentially overcome by integrating communication,computing,caching,and control(i4C)technologies.In this survey,we first give a snapshot of different aspects of the i4C,comprising background,motivation,leading technological enablers,potential applications,and use cases.Next,we describe different models of communication,computing,caching,and control(4C)to lay the foundation of the integration approach.We review current stateof-the-art research efforts related to the i4C,focusing on recent trends of both conventional and artificial intelligence(AI)-based integration approaches.We also highlight the need for intelligence in resources integration.Then,we discuss the integration of sensing and communication(ISAC)and classify the integration approaches into various classes.Finally,we propose open challenges and present future research directions for beyond 5G networks,such as 6G.展开更多
With only a few deep-level defect states having a high formation energy and dominance of shallow carrier non-trapping defects,the defect-tolerant electronic and optical properties of lead halide perovskites have made ...With only a few deep-level defect states having a high formation energy and dominance of shallow carrier non-trapping defects,the defect-tolerant electronic and optical properties of lead halide perovskites have made them appealing materials for high-efficiency,low-cost,solar cells and light-emitting devices.As such,recent observations of apparently deep-level and highly luminescent states in low-dimensional perovskites have attracted enormous attention as well as intensive debates.The observed green emission in 2D CsPb2Br5 and 0 D Cs4PbBr6 poses an enigma over whether it is originated from intrinsic point defects or simply from highly luminescent CsPbBr3 nanocrystals embedded in the otherwise transparent wide band gap semiconductors.The nature of deep-level edge emission in 2D Ruddlesden–Popper perovskites is also not well understood.In this mini review,the experimental evidences that support the opposing interpretations are analyzed,and challenges and root causes forthe controversy are discussed.Shortcomings in the current density functional theory approaches to modeling of properties and intrinsic point defects in lead halide perovskites are also noted.Selected experimental approaches are suggested to better correlate property with structure of a material and help resolve the controversies.Understanding and identification of the origin of luminescent centers will help design and engineer perovskites for wide device applications.展开更多
Optical coherence tomography(OCT)provides significant advantages of high resolution(approaching the histopathology level)realtime imaging of tsess without use of contrast agents.Based on these advantages,the microstru...Optical coherence tomography(OCT)provides significant advantages of high resolution(approaching the histopathology level)realtime imaging of tsess without use of contrast agents.Based on these advantages,the microstructural features of tumors can be visualized and detected intra-operatively.However,it is still not clinically accepted for tumor margin delin-eation due to poor specificity and accuracy.In contrast,Raman spectroscopy(RS)can obtain tissue information at the molecular level,but does not provide real-time inaging capability.Therefore,combining OCT and RS could provide synergy.To this end,we present a tissue analysis and dassification method using both the slope of OCT intensity signal Vs depth and the principle components from the RS spectrum as the indicators for tissuse characterization.The goal of this study was to understand prediction accuracy of OCT and combined OCT/RS method for dassification of optically similar tisues and organs.Our pilot experiments were performed on mouse kidneys,livers,and small intestines(SIs).The prediction accuracy with five-fold cross validation of the method has been evaluated by the support vector machine(SVM)method.The results demonstrate that tissue characterization based on the OCT/RS method was superior compared to using OCT structural information alone.This combined OCT/RS method is potentially useful as a noninvasive optical biopsy technique for rapid and automatic tissue characterization during surgery.展开更多
Transportation accounts for about 20%of the global green-house gas emissions,which is a major source of greenhouse gases.Road transportation accounts for three quarters of this share,while aviation and maritime transp...Transportation accounts for about 20%of the global green-house gas emissions,which is a major source of greenhouse gases.Road transportation accounts for three quarters of this share,while aviation and maritime transportation each account for 11%(see Figure 1).展开更多
Thermally responsive liquid crystal elastomers (LCEs) hold great promise in applications of soft robots and actuators because of the induced size and shape change with temperature. Experiments have successfully demons...Thermally responsive liquid crystal elastomers (LCEs) hold great promise in applications of soft robots and actuators because of the induced size and shape change with temperature. Experiments have successfully demonstrated that the LCE based bimorphs can be effective soft robots once integrated with soft sensors and thermal actuators. Here, we present an analytical transient thermo-mechanical model for a bimorph structure based soft robot, which consists of a strip of LCE and a thermal inert polymer actuated by an ultra-thin stretchable open-mesh shaped heater to mimic the unique locomotion behaviors of an inchworm. The coupled mechanical and thermal analysis based on the thermo-mechanical theory is carried out to underpin the transient bending behavior, and a systematic understanding is therefore achieved. The key analytical results reveal that the thickness and the modulus ratio of the LCE and the inert polymer layer dominate the transient bending deformation. The analytical results will not only render fundamental understanding of the actuation of bimorph structures, but also facilitate the rational design of soft robotics.展开更多
Interaction with the substrate plays an essential role in determining the structure and electronic property of graphene supported by a surface.We observe a maze-like reconstruction pattern in graphene on flat copper f...Interaction with the substrate plays an essential role in determining the structure and electronic property of graphene supported by a surface.We observe a maze-like reconstruction pattern in graphene on flat copper foil.With functionalized scanning tunneling microscope tips,a triangular three-for-six structure of graphene and a mixed(2√2×√2)R45°reconstruction of a Cu(100)surface are separately visualized at the atomic scale.Substrate-induced changes in the structure and electronic property are further illustrated by micro-Raman spectroscopy and scanning tunneling spectroscopy.This finding suggests a new method to effectively induce partial sp3 hybridization in a single-layer graphene and therefore to tune its electronic property through interaction with the substrate.展开更多
One of the major challenges in imaging biological tissues using optical techniques,such as optical coherence tomography(OCT),is the lack of light penetration due to highly turbid structures within the tissue.Optical c...One of the major challenges in imaging biological tissues using optical techniques,such as optical coherence tomography(OCT),is the lack of light penetration due to highly turbid structures within the tissue.Optical clearing techniques enable the biological samples to be more optically homogeneous,allowing for deeper penetration of light into the tissue.This study investigates the effect of optical clearing utilizing various concentrations of glucose solution(10%,30%,and 50%)on porcine skin.A gold-plated mirror was imaged beneath the tissue and percentage clearing was determined by monitoring the change in reflected light intensity from the mirror over time.The ratio of percentage clearing per tissue thickness for 10%,30% and 50% glucose was determined to be 4.7±1.6%mm^(−1)(n=6),10.6±2.0%mm^(−1)(n=7)and 21.8±2.2%mm^(−1)(n=5),respectively.It was concluded that while higher glucose concentration has the highest optical clearing effect,a suitable concentration should be chosen for the purpose of clearing,considering the osmotic stress on the tissue sample.展开更多
Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wirel...Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wireless propagation environment and the broad coverage pose severe threats to the protection of private data. Emerging covert communications provides a promising solution to achieve robust communication security. Aiming at facilitating the practical implementation of covert communications in space/air networks, we present a tutorial overview of its potentials, scenarios, and key technologies. Specifically, first, the commonly used covertness constraint model, covert performance metrics, and potential application scenarios are briefly introduced. Then, several efficient methods that introduce uncertainty into the covert system are thoroughly summarized, followed by several critical enabling technologies, including joint resource allocation and deployment/trajectory design, multi-antenna and beamforming techniques, reconfigurable intelligent surface(RIS), and artificial intelligence algorithms. Finally, we highlight some open issues for future investigation.展开更多
Non-Orthogonal Multiple Access(NOMA)has already proven to be an effective multiple access scheme for5th Generation(5G)wireless networks.It provides improved performance in terms of system throughput,spectral efficienc...Non-Orthogonal Multiple Access(NOMA)has already proven to be an effective multiple access scheme for5th Generation(5G)wireless networks.It provides improved performance in terms of system throughput,spectral efficiency,fairness,and energy efficiency(EE).However,in conventional NOMA networks,performance degradation still exists because of the stochastic behavior of wireless channels.To combat this challenge,the concept of Intelligent Reflecting Surface(IRS)has risen to prominence as a low-cost intelligent solution for Beyond 5G(B5G)networks.In this paper,a modeling primer based on the integration of these two cutting-edge technologies,i.e.,IRS and NOMA,for B5G wireless networks is presented.An in-depth comparative analysis of IRS-assisted Power Domain(PD)-NOMA networks is provided through 3-fold investigations.First,a primer is presented on the system architecture of IRS-enabled multiple-configuration PD-NOMA systems,and parallels are drawn with conventional network configurations,i.e.,conventional NOMA,Orthogonal Multiple Access(OMA),and IRS-assisted OMA networks.Followed by this,a comparative analysis of these network configurations is showcased in terms of significant performance metrics,namely,individual users'achievable rate,sum rate,ergodic rate,EE,and outage probability.Moreover,for multi-antenna IRS-enabled NOMA networks,we exploit the active Beamforming(BF)technique by employing a greedy algorithm using a state-of-the-art branch-reduceand-bound(BRB)method.The optimality of the BRB algorithm is presented by comparing it with benchmark BF techniques,i.e.,minimum-mean-square-error,zero-forcing-BF,and maximum-ratio-transmission.Furthermore,we present an outlook on future envisioned NOMA networks,aided by IRSs,i.e.,with a variety of potential applications for 6G wireless networks.This work presents a generic performance assessment toolkit for wireless networks,focusing on IRS-assisted NOMA networks.This comparative analysis provides a solid foundation for the development of future IRS-enabled,energy-efficient wireless communication systems.展开更多
The manufacturing process of all-solid-state batteries necessitates the use of polymer binders.However,these binders,being ionic insulators by nature,can adversely affect charge transport within composite cathodes,the...The manufacturing process of all-solid-state batteries necessitates the use of polymer binders.However,these binders,being ionic insulators by nature,can adversely affect charge transport within composite cathodes,thereby impacting the rate performance of the batteries.In this work,we aim to investigate the impact of fabrication methods,specifically the solvent-free dry process versus the slurry-cast wet process,on binder distribution and charge transport in composite cathodes of solid-state batteries.In the dry process,the binder forms a fibrous network,while the wet process results in binder coverage on the surface of cathode active materials.The difference in microstructure leads to a notable 20-fold increase in ionic conductivity in the dry-processed cathode.Consequently,the cells processed via the dry method exhibit higher capacity retention of 89%and 83%at C/3 and C/2 rates,respectively,in comparison to 68%and 58%for the wet-processed cells at the same rate.These findings provide valuable insights into the influence of fabrication methods on binder distribution and charge transport,contributing to a better understanding of the binder’s role in manufacturing of all-solid-state batteries.展开更多
As Information,Communications,and Data Technology(ICDT)are deeply integrated,the research of 6G gradually rises.Meanwhile,federated learning(FL)as a distributed artificial intelligence(AI)framework is generally believ...As Information,Communications,and Data Technology(ICDT)are deeply integrated,the research of 6G gradually rises.Meanwhile,federated learning(FL)as a distributed artificial intelligence(AI)framework is generally believed to be the most promising solution to achieve“Native AI”in 6G.While the adoption of energy as a metric in AI and wireless networks is emerging,most studies still focused on obtaining high levels of accuracy,with little consideration on new features of future networks and their possible impact on energy consumption.To address this issue,this article focuses on green concerns in FL over 6G.We first analyze and summarize major energy consumption challenges caused by technical characteristics of FL and the dynamical heterogeneity of 6G networks,and model the energy consumption in FL over 6G from aspects of computation and communication.We classify and summarize the basic ways to reduce energy,and present several feasible green designs for FL-based 6G network architecture from three perspectives.According to the simulation results,we provide a useful guideline to researchers that different schemes should be used to achieve the minimum energy consumption at a reasonable cost of learning accuracy for different network scenarios and service requirements in FL-based 6G network.展开更多
Location-based services(LBS)in vehicular ad hoc networks(VANETs)must protect users’privacy and address the threat of the exposure of sensitive locations during LBS requests.Users release not only their geographical b...Location-based services(LBS)in vehicular ad hoc networks(VANETs)must protect users’privacy and address the threat of the exposure of sensitive locations during LBS requests.Users release not only their geographical but also semantic information of the visited places(e.g.,hospital).This sensitive information enables the inference attacker to exploit the users’preferences and life patterns.In this paper we propose a reinforcement learning(RL)based sensitive semantic location privacy protection scheme.This scheme uses the idea of differential privacy to randomize the released vehicle locations and adaptively selects the perturbation policy based on the sensitivity of the semantic location and the attack history.This scheme enables a vehicle to optimize the perturbation policy in terms of the privacy and the quality of service(QoS)loss without being aware of the current inference attack model in a dynamic privacy protection process.To solve the location protection problem with high-dimensional and continuous-valued perturbation policy variables,a deep deterministic policy gradientbased semantic location perturbation scheme(DSLP)is developed.The actor part is used to generate continuous privacy budget and perturbation angle,and the critic part is used to estimate the performance of the policy.Simulations demonstrate the DSLP-based scheme outperforms the benchmark schemes,which increases the privacy,reduces the QoS loss,and increases the utility of the vehicle.展开更多
This paper reports that the Si＋ self-ion-implantation are conducted on the silicon-on-insulator wafers with the 2SSi＋ doses of 7 ×1012, 1 × 1013, 4 × 1013, and 3× 1014 cm-2, respectively. After t...This paper reports that the Si＋ self-ion-implantation are conducted on the silicon-on-insulator wafers with the 2SSi＋ doses of 7 ×1012, 1 × 1013, 4 × 1013, and 3× 1014 cm-2, respectively. After the suitable annealing, these samples are characterized by using the photoluminescence technique at different recorded temperatures. Plentiful emission peaks are observed in these implanted silicon-on-insulator samples, including the unwonted intense P~ band which exhibits a great potential in the optoelectronic application. These results indicate that severe transformation of the interstitial clusters can be manipulated by the implanting dose at suitable annealing temperatures. The high critical temperatures for the photoluminescence intensity growth of the two signatures are well discussed based on the thermal ionization model of free exciton.展开更多
Device-free gesture recognition is an emerging wireless sensing technique which could recognize gestures by analyzing its influence on surrounding wireless signals,it may empower wireless networks with the augmented s...Device-free gesture recognition is an emerging wireless sensing technique which could recognize gestures by analyzing its influence on surrounding wireless signals,it may empower wireless networks with the augmented sensing ability.Researchers have made great achievements for singleperson device-free gesture recognition.However,when multiple persons conduct gestures simultaneously,the received signals will be mixed together,and thus traditional methods would not work well anymore.Moreover,the anonymity of persons and the change in the surrounding environment would cause feature shift and mismatch,and thus the recognition accuracy would degrade remarkably.To address these problems,we explore and exploit the diversity of spatial information and propose a multidimensional analysis method to separate the gesture feature of each person using a focusing sensing strategy.Meanwhile,we also present a deep-learning based robust device free gesture recognition framework,which leverages an adversarial approach to extract robust gesture feature that is insensitive to the change of persons and environment.Furthermore,we also develop a 77GHz mmWave prototype system and evaluate the proposed methods extensively.Experimental results reveal that the proposed system can achieve average accuracies of 93%and 84%when 10 gestures are conducted in Received:Jun.18,2020 Revised:Aug.06,2020 Editor:Ning Ge different environments by two and four persons simultaneously,respectively.展开更多
The integration of Mixed Reality(MR)technology into Autonomous Vehicles(AVs)has ushered in a new era for the automotive industry,offering heightened safety,convenience,and passenger comfort.However,the substantial and...The integration of Mixed Reality(MR)technology into Autonomous Vehicles(AVs)has ushered in a new era for the automotive industry,offering heightened safety,convenience,and passenger comfort.However,the substantial and varied data generated by MR-Connected AVs(MR-CAVs),encompassing both highly dynamic and static information,presents formidable challenges for efficient data management and retrieval.In this paper,we formulate our indexing problem as a constrained optimization problem,with the aim of maximizing the utility function that represents the overall performance of our indexing system.This optimization problem encompasses multiple decision variables and constraints,rendering it mathematically infeasible to solve directly.Therefore,we propose a heuristic algorithm to address the combinatorial complexity of the problem.Our heuristic indexing algorithm efficiently divides data into highly dynamic and static categories,distributing the index across Roadside Units(RSUs)and optimizing query processing.Our approach takes advantage of the computational capabilities of edge servers or RSUs to perform indexing operations,thereby shifting the burden away from the vehicles themselves.Our algorithm strategically places data in the cache,optimizing cache hit rate and space utilization while reducing latency.The quantitative evaluation demonstrates the superiority of our proposed scheme,with significant reductions in latency(averaging 27%-49.25%),a 30.75%improvement in throughput,a 22.50%enhancement in cache hit rate,and a 32%-50.75%improvement in space utilization compared to baseline schemes.展开更多
Industrialized buildings,characterized by off-site manufacturing and on-site installation,offer notable improvements in efficiency,cost-effectiveness,and material use.This transition from traditional construction meth...Industrialized buildings,characterized by off-site manufacturing and on-site installation,offer notable improvements in efficiency,cost-effectiveness,and material use.This transition from traditional construction methods not only accelerates building processes but also enhances working efficiencies globally.Despite its widespread adoption,the performance of industrialized building manufacturing(IBM)can still be optimized,particularly in enhancing time efficiency and reducing costs.This paper explores the integration of Artificial Intelligence(AI)and robotics at IBM to improve efficiency,cost-effectiveness,and material use in off-site assembly.Through a narrative literature review,this study systematically categorizes AI-based Robots(AIRs)applications into four critical stages—Cognition,Communication,Control,and Collab-oration and Coordination,and then investigates their appli-cation in the factory assembly process for industrialized buildings,which is structured into distinct stages:compo-nent preparation,sub-assembly,main assembly,finishing tasks,and quality control.Each stage,from positioning components to the integration of larger modules and subsequent quality inspection,often involves robots or human-robot collaboration to enhance precision and effi-ciency.By examining research from 2014 to 2024,the review highlights the significant improvements AI-based robots have introduced to the construction sector,identifies existing challenges,and outlines future research directions.This comprehensive analysis aims to establish more effi-cient,precise,and tailored construction processes,paving the way for advanced IBM.展开更多
This paper presents a new Wireless Power Transfer(WPT)approach by aligning the phases of a group of spatially distributed Radio Frequency(RF)transmitters(TX)at the target receiver(RX)device.Our approach can transfer e...This paper presents a new Wireless Power Transfer(WPT)approach by aligning the phases of a group of spatially distributed Radio Frequency(RF)transmitters(TX)at the target receiver(RX)device.Our approach can transfer energy over tens of meters and even to targets blocked by obstacles.Compared to popular beamforming based WPTs,our approach leads to a drastically different energy density distribution:the energy density at the target receiver is much higher than the energy density at other locations.Due to this unique energy distribution pattern,our approach offers a safer WPT solution,which can be potentially scaled up to ship a higher level of energy over longer distances.Specifically,we model the energy density distribution and prove that our proposed system can create a high energy peak exactly at the target receiver.Then we conduct detailed simulation studies to investigate how the actual energy distribution is impacted by various important system parameters,including number/topology of transmitters,transmitter antenna directionality,the distance between receiver and transmitters,and environmental multipath.Finally,we build an actual prototype with 17 N210 and 4 B210 Universal Software Radio Peripheral(USRP)nodes,through which we validate the salient features and performance promises of the proposed system.展开更多
As renewable energy is becoming the major re-source in future power grids,the weather and climate can have a higher impact on grid reliability.Transmission expansion planning(TEP)has the potential to reinforce the pow...As renewable energy is becoming the major re-source in future power grids,the weather and climate can have a higher impact on grid reliability.Transmission expansion planning(TEP)has the potential to reinforce the power trans-fer capability of a transmission network for climate-impacted power grids.In this paper,we propose a systematic TEP proce-dure for renewable-energy-dominated power grids considering climate impact(CI).Particularly,this paper develops an im-proved model for TEP considering climate impact(TEP-CI)and evaluates the reliability of power grid with the obtained transmission investment plan.Firstly,we create climate-impact-ed spatio-temporal future power grid data to facilitate the study of TEP-CI,which include the future climate-dependent re-newable power generation as well as the dynamic line rating profiles of the Texas 123-bus backbone transmission(TX-123BT)system.Secondly,the TEP-CI model is proposed,which considers the variation in renewable power generation and dy-namic line rating,and the investment plan for future TX-123BT system is obtained.Thirdly,a customized security-con-strained unit commitment(SCUC)is presented specifically for climate-impacted power grids.The reliability of future power grid in various investment scenarios is analyzed based on the daily operation conditions from SCUC simulations.The whole procedure presented in this paper enables numerical studies on power grid planning considering climate impact.It can also serve as a benchmark for other studies of the TEP-CI model and its performance evaluation.展开更多
文摘Anumber of research papers including several review papers have reported that autonomous vehicles(AVs)consume a significant amount of power to run the onboard computers that do all the calculations needed to process and analyze the sig-nificant amount of data.In addition,there is a substantial amount of power consumption by onboard sensors including radars,cam-eras,Lidars,etc.[1]The resulting power consumption results in range reduction in electric autonomous vehicles.This in-turn increases the emissions based on how the electricity is obtained for charging these vehicle batteries.As the degree of automation moves up the ladder of AVs,the complexity of the overall control,management,and the associated tasks grow exponentially,and hence increasing the power consumption.The Society of Auto-motive Engineers(SAE)defines 6 levels of driving automation ranging from Level 0(fully manual)to Level 5(fully autonomous).Level 0 is no driving automation and the driver is responsible for full control of the vehicle.Level 1 is the driver assisted by a support system like adaptive cruise control or lane-changing assistance,but the driver must remain engaged.In Level 2.
基金supported in part by National Key R&D Program of China(2019YFE0196400)Key Research and Development Program of Shaanxi(2022KWZ09)+4 种基金National Natural Science Foundation of China(61771358,61901317,62071352)Fundamental Research Funds for the Central Universities(JB190104)Joint Education Project between China and Central-Eastern European Countries(202005)the 111 Project(B08038)。
文摘In recent years,the exponential proliferation of smart devices with their intelligent applications poses severe challenges on conventional cellular networks.Such challenges can be potentially overcome by integrating communication,computing,caching,and control(i4C)technologies.In this survey,we first give a snapshot of different aspects of the i4C,comprising background,motivation,leading technological enablers,potential applications,and use cases.Next,we describe different models of communication,computing,caching,and control(4C)to lay the foundation of the integration approach.We review current stateof-the-art research efforts related to the i4C,focusing on recent trends of both conventional and artificial intelligence(AI)-based integration approaches.We also highlight the need for intelligence in resources integration.Then,we discuss the integration of sensing and communication(ISAC)and classify the integration approaches into various classes.Finally,we propose open challenges and present future research directions for beyond 5G networks,such as 6G.
基金support from the Robert A.Welch Foundation(E-1728)National Science Foundation(EEC-1530753)supported by the State of Texas through the Texas Center for superconductivity at the University of Houston
文摘With only a few deep-level defect states having a high formation energy and dominance of shallow carrier non-trapping defects,the defect-tolerant electronic and optical properties of lead halide perovskites have made them appealing materials for high-efficiency,low-cost,solar cells and light-emitting devices.As such,recent observations of apparently deep-level and highly luminescent states in low-dimensional perovskites have attracted enormous attention as well as intensive debates.The observed green emission in 2D CsPb2Br5 and 0 D Cs4PbBr6 poses an enigma over whether it is originated from intrinsic point defects or simply from highly luminescent CsPbBr3 nanocrystals embedded in the otherwise transparent wide band gap semiconductors.The nature of deep-level edge emission in 2D Ruddlesden–Popper perovskites is also not well understood.In this mini review,the experimental evidences that support the opposing interpretations are analyzed,and challenges and root causes forthe controversy are discussed.Shortcomings in the current density functional theory approaches to modeling of properties and intrinsic point defects in lead halide perovskites are also noted.Selected experimental approaches are suggested to better correlate property with structure of a material and help resolve the controversies.Understanding and identification of the origin of luminescent centers will help design and engineer perovskites for wide device applications.
基金supported in part by the grants to Kirill Larin from NIH 1R01EY022362,1R01HL120140,U54HG006348,and DOD PRJ71Tsupported by grants to Wei-Chuan Shih from NSF CAREER Award (CBET-1151154)+1 种基金NASA Early Career Faculty Grant (NNX12AQ44G)Gulf of Mexico Research Initiative (GoMRI-030).
文摘Optical coherence tomography(OCT)provides significant advantages of high resolution(approaching the histopathology level)realtime imaging of tsess without use of contrast agents.Based on these advantages,the microstructural features of tumors can be visualized and detected intra-operatively.However,it is still not clinically accepted for tumor margin delin-eation due to poor specificity and accuracy.In contrast,Raman spectroscopy(RS)can obtain tissue information at the molecular level,but does not provide real-time inaging capability.Therefore,combining OCT and RS could provide synergy.To this end,we present a tissue analysis and dassification method using both the slope of OCT intensity signal Vs depth and the principle components from the RS spectrum as the indicators for tissuse characterization.The goal of this study was to understand prediction accuracy of OCT and combined OCT/RS method for dassification of optically similar tisues and organs.Our pilot experiments were performed on mouse kidneys,livers,and small intestines(SIs).The prediction accuracy with five-fold cross validation of the method has been evaluated by the support vector machine(SVM)method.The results demonstrate that tissue characterization based on the OCT/RS method was superior compared to using OCT structural information alone.This combined OCT/RS method is potentially useful as a noninvasive optical biopsy technique for rapid and automatic tissue characterization during surgery.
文摘Transportation accounts for about 20%of the global green-house gas emissions,which is a major source of greenhouse gases.Road transportation accounts for three quarters of this share,while aviation and maritime transportation each account for 11%(see Figure 1).
基金Project supported by the National Basic Research Program(No.2015CB351901)the National Natural Science Foundation of China(Nos.11372272,11622221,11621062,11502009,and 11772030)+2 种基金the Doctoral New Investigator Grant from American Chemical Society Petroleum Research Fund of the National Science Foundation(Nos.1509763 and 1554499)the Opening Fund of State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi’an Jiaotong University(No.SV2018-KF-13)the Fundamental Research Funds for the Central Universities(No.2017XZZX002-11)
文摘Thermally responsive liquid crystal elastomers (LCEs) hold great promise in applications of soft robots and actuators because of the induced size and shape change with temperature. Experiments have successfully demonstrated that the LCE based bimorphs can be effective soft robots once integrated with soft sensors and thermal actuators. Here, we present an analytical transient thermo-mechanical model for a bimorph structure based soft robot, which consists of a strip of LCE and a thermal inert polymer actuated by an ultra-thin stretchable open-mesh shaped heater to mimic the unique locomotion behaviors of an inchworm. The coupled mechanical and thermal analysis based on the thermo-mechanical theory is carried out to underpin the transient bending behavior, and a systematic understanding is therefore achieved. The key analytical results reveal that the thickness and the modulus ratio of the LCE and the inert polymer layer dominate the transient bending deformation. The analytical results will not only render fundamental understanding of the actuation of bimorph structures, but also facilitate the rational design of soft robotics.
基金the National Natural Science Foundation of China under Grant Nos 11174347,61027011 and 10974245the National Basic Research Program of China under Grant No 2012CB933002+2 种基金the Chinese Academic of Sciences under Grant No 1731300500030the Robert a Welch Foundation(E-1728)the National Science Foundation(DMR-0907336,ECCS-1240510).
文摘Interaction with the substrate plays an essential role in determining the structure and electronic property of graphene supported by a surface.We observe a maze-like reconstruction pattern in graphene on flat copper foil.With functionalized scanning tunneling microscope tips,a triangular three-for-six structure of graphene and a mixed(2√2×√2)R45°reconstruction of a Cu(100)surface are separately visualized at the atomic scale.Substrate-induced changes in the structure and electronic property are further illustrated by micro-Raman spectroscopy and scanning tunneling spectroscopy.This finding suggests a new method to effectively induce partial sp3 hybridization in a single-layer graphene and therefore to tune its electronic property through interaction with the substrate.
基金the Institute of Biomedical Imaging Sciences(IBIS-97708)CRDF(RUB1-2932-SR-08)+3 种基金NSF(CMMI-0900743)supported by grants 224014 Photonics4life-FP7-ICT-2007-2RF Ministry of Science and Education 2.1.1/4989 and 2.2.1.1/2950,Project 1.4.09 of Federal Agency of Education of RFthe RF Governmental contracts 02.740.11.0484 and 02.740.11.0770.
文摘One of the major challenges in imaging biological tissues using optical techniques,such as optical coherence tomography(OCT),is the lack of light penetration due to highly turbid structures within the tissue.Optical clearing techniques enable the biological samples to be more optically homogeneous,allowing for deeper penetration of light into the tissue.This study investigates the effect of optical clearing utilizing various concentrations of glucose solution(10%,30%,and 50%)on porcine skin.A gold-plated mirror was imaged beneath the tissue and percentage clearing was determined by monitoring the change in reflected light intensity from the mirror over time.The ratio of percentage clearing per tissue thickness for 10%,30% and 50% glucose was determined to be 4.7±1.6%mm^(−1)(n=6),10.6±2.0%mm^(−1)(n=7)and 21.8±2.2%mm^(−1)(n=5),respectively.It was concluded that while higher glucose concentration has the highest optical clearing effect,a suitable concentration should be chosen for the purpose of clearing,considering the osmotic stress on the tissue sample.
基金supported in part by the National Natural Science Foundation of China(NSFC)under grant numbers U22A2007 and 62171010the Beijing Natural Science Foundation under grant number L212003.
文摘Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wireless propagation environment and the broad coverage pose severe threats to the protection of private data. Emerging covert communications provides a promising solution to achieve robust communication security. Aiming at facilitating the practical implementation of covert communications in space/air networks, we present a tutorial overview of its potentials, scenarios, and key technologies. Specifically, first, the commonly used covertness constraint model, covert performance metrics, and potential application scenarios are briefly introduced. Then, several efficient methods that introduce uncertainty into the covert system are thoroughly summarized, followed by several critical enabling technologies, including joint resource allocation and deployment/trajectory design, multi-antenna and beamforming techniques, reconfigurable intelligent surface(RIS), and artificial intelligence algorithms. Finally, we highlight some open issues for future investigation.
基金supported by Higher Education Commission(HEC)of Pakistan through its National Research Program for Universities(NRPU)[Ref.No.20-14560/NRPU/R&D/HEC/2021]support provided by HEC。
文摘Non-Orthogonal Multiple Access(NOMA)has already proven to be an effective multiple access scheme for5th Generation(5G)wireless networks.It provides improved performance in terms of system throughput,spectral efficiency,fairness,and energy efficiency(EE).However,in conventional NOMA networks,performance degradation still exists because of the stochastic behavior of wireless channels.To combat this challenge,the concept of Intelligent Reflecting Surface(IRS)has risen to prominence as a low-cost intelligent solution for Beyond 5G(B5G)networks.In this paper,a modeling primer based on the integration of these two cutting-edge technologies,i.e.,IRS and NOMA,for B5G wireless networks is presented.An in-depth comparative analysis of IRS-assisted Power Domain(PD)-NOMA networks is provided through 3-fold investigations.First,a primer is presented on the system architecture of IRS-enabled multiple-configuration PD-NOMA systems,and parallels are drawn with conventional network configurations,i.e.,conventional NOMA,Orthogonal Multiple Access(OMA),and IRS-assisted OMA networks.Followed by this,a comparative analysis of these network configurations is showcased in terms of significant performance metrics,namely,individual users'achievable rate,sum rate,ergodic rate,EE,and outage probability.Moreover,for multi-antenna IRS-enabled NOMA networks,we exploit the active Beamforming(BF)technique by employing a greedy algorithm using a state-of-the-art branch-reduceand-bound(BRB)method.The optimality of the BRB algorithm is presented by comparing it with benchmark BF techniques,i.e.,minimum-mean-square-error,zero-forcing-BF,and maximum-ratio-transmission.Furthermore,we present an outlook on future envisioned NOMA networks,aided by IRSs,i.e.,with a variety of potential applications for 6G wireless networks.This work presents a generic performance assessment toolkit for wireless networks,focusing on IRS-assisted NOMA networks.This comparative analysis provides a solid foundation for the development of future IRS-enabled,energy-efficient wireless communication systems.
基金supported by the U.S.Department of Energy’s Office of Energy Efficiency and Renewable Energy(EERE)under the Vehicle Technologies Program under Contact DE-EE0008864.
文摘The manufacturing process of all-solid-state batteries necessitates the use of polymer binders.However,these binders,being ionic insulators by nature,can adversely affect charge transport within composite cathodes,thereby impacting the rate performance of the batteries.In this work,we aim to investigate the impact of fabrication methods,specifically the solvent-free dry process versus the slurry-cast wet process,on binder distribution and charge transport in composite cathodes of solid-state batteries.In the dry process,the binder forms a fibrous network,while the wet process results in binder coverage on the surface of cathode active materials.The difference in microstructure leads to a notable 20-fold increase in ionic conductivity in the dry-processed cathode.Consequently,the cells processed via the dry method exhibit higher capacity retention of 89%and 83%at C/3 and C/2 rates,respectively,in comparison to 68%and 58%for the wet-processed cells at the same rate.These findings provide valuable insights into the influence of fabrication methods on binder distribution and charge transport,contributing to a better understanding of the binder’s role in manufacturing of all-solid-state batteries.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFB1806804)the U.S.National Science Foundation(Grant US CNS-1801925,CNS-2029569,and CNS-2107057)。
文摘As Information,Communications,and Data Technology(ICDT)are deeply integrated,the research of 6G gradually rises.Meanwhile,federated learning(FL)as a distributed artificial intelligence(AI)framework is generally believed to be the most promising solution to achieve“Native AI”in 6G.While the adoption of energy as a metric in AI and wireless networks is emerging,most studies still focused on obtaining high levels of accuracy,with little consideration on new features of future networks and their possible impact on energy consumption.To address this issue,this article focuses on green concerns in FL over 6G.We first analyze and summarize major energy consumption challenges caused by technical characteristics of FL and the dynamical heterogeneity of 6G networks,and model the energy consumption in FL over 6G from aspects of computation and communication.We classify and summarize the basic ways to reduce energy,and present several feasible green designs for FL-based 6G network architecture from three perspectives.According to the simulation results,we provide a useful guideline to researchers that different schemes should be used to achieve the minimum energy consumption at a reasonable cost of learning accuracy for different network scenarios and service requirements in FL-based 6G network.
基金This work was supported in part by National Natural Science Foundation of China under Grant 61971366 and 61771474,and in part by the Fundamental Research Funds for the central universities No.20720200077,and in part by Major Science and Technology Innovation Projects of Shandong Province 2019JZZY020505 and Key R&D Projects of Xuzhou City KC18171,and in part by NSF EARS-1839818,CNS1717454,CNS-1731424,and CNS-1702850.
文摘Location-based services(LBS)in vehicular ad hoc networks(VANETs)must protect users’privacy and address the threat of the exposure of sensitive locations during LBS requests.Users release not only their geographical but also semantic information of the visited places(e.g.,hospital).This sensitive information enables the inference attacker to exploit the users’preferences and life patterns.In this paper we propose a reinforcement learning(RL)based sensitive semantic location privacy protection scheme.This scheme uses the idea of differential privacy to randomize the released vehicle locations and adaptively selects the perturbation policy based on the sensitivity of the semantic location and the attack history.This scheme enables a vehicle to optimize the perturbation policy in terms of the privacy and the quality of service(QoS)loss without being aware of the current inference attack model in a dynamic privacy protection process.To solve the location protection problem with high-dimensional and continuous-valued perturbation policy variables,a deep deterministic policy gradientbased semantic location perturbation scheme(DSLP)is developed.The actor part is used to generate continuous privacy budget and perturbation angle,and the critic part is used to estimate the performance of the policy.Simulations demonstrate the DSLP-based scheme outperforms the benchmark schemes,which increases the privacy,reduces the QoS loss,and increases the utility of the vehicle.
基金supported by the National Natural Science Foundation of China (Grant No. 10964016)the Key Project of the Chinese Ministry of Education (Grant No. 210207)the Natural Science Foundation of Yunnan University (Grant No. 2009E27Q)
文摘This paper reports that the Si＋ self-ion-implantation are conducted on the silicon-on-insulator wafers with the 2SSi＋ doses of 7 ×1012, 1 × 1013, 4 × 1013, and 3× 1014 cm-2, respectively. After the suitable annealing, these samples are characterized by using the photoluminescence technique at different recorded temperatures. Plentiful emission peaks are observed in these implanted silicon-on-insulator samples, including the unwonted intense P~ band which exhibits a great potential in the optoelectronic application. These results indicate that severe transformation of the interstitial clusters can be manipulated by the implanting dose at suitable annealing temperatures. The high critical temperatures for the photoluminescence intensity growth of the two signatures are well discussed based on the thermal ionization model of free exciton.
基金This work was supported by National Natural Science Foundation of China under grants U1933104 and 62071081LiaoNing Revitalization Talents Program under grant XLYC1807019,Liaoning Province Natural Science Foundation under grants 2019-MS-058+1 种基金Dalian Science and Technology Innovation Foundation under grant 2018J12GX044Fundamental Research Funds for the Central Universities under grants DUT20LAB113 and DUT20JC07,and Cooperative Scientific Research Project of Chunhui Plan of Ministry of Education.
文摘Device-free gesture recognition is an emerging wireless sensing technique which could recognize gestures by analyzing its influence on surrounding wireless signals,it may empower wireless networks with the augmented sensing ability.Researchers have made great achievements for singleperson device-free gesture recognition.However,when multiple persons conduct gestures simultaneously,the received signals will be mixed together,and thus traditional methods would not work well anymore.Moreover,the anonymity of persons and the change in the surrounding environment would cause feature shift and mismatch,and thus the recognition accuracy would degrade remarkably.To address these problems,we explore and exploit the diversity of spatial information and propose a multidimensional analysis method to separate the gesture feature of each person using a focusing sensing strategy.Meanwhile,we also present a deep-learning based robust device free gesture recognition framework,which leverages an adversarial approach to extract robust gesture feature that is insensitive to the change of persons and environment.Furthermore,we also develop a 77GHz mmWave prototype system and evaluate the proposed methods extensively.Experimental results reveal that the proposed system can achieve average accuracies of 93%and 84%when 10 gestures are conducted in Received:Jun.18,2020 Revised:Aug.06,2020 Editor:Ning Ge different environments by two and four persons simultaneously,respectively.
文摘The integration of Mixed Reality(MR)technology into Autonomous Vehicles(AVs)has ushered in a new era for the automotive industry,offering heightened safety,convenience,and passenger comfort.However,the substantial and varied data generated by MR-Connected AVs(MR-CAVs),encompassing both highly dynamic and static information,presents formidable challenges for efficient data management and retrieval.In this paper,we formulate our indexing problem as a constrained optimization problem,with the aim of maximizing the utility function that represents the overall performance of our indexing system.This optimization problem encompasses multiple decision variables and constraints,rendering it mathematically infeasible to solve directly.Therefore,we propose a heuristic algorithm to address the combinatorial complexity of the problem.Our heuristic indexing algorithm efficiently divides data into highly dynamic and static categories,distributing the index across Roadside Units(RSUs)and optimizing query processing.Our approach takes advantage of the computational capabilities of edge servers or RSUs to perform indexing operations,thereby shifting the burden away from the vehicles themselves.Our algorithm strategically places data in the cache,optimizing cache hit rate and space utilization while reducing latency.The quantitative evaluation demonstrates the superiority of our proposed scheme,with significant reductions in latency(averaging 27%-49.25%),a 30.75%improvement in throughput,a 22.50%enhancement in cache hit rate,and a 32%-50.75%improvement in space utilization compared to baseline schemes.
文摘Industrialized buildings,characterized by off-site manufacturing and on-site installation,offer notable improvements in efficiency,cost-effectiveness,and material use.This transition from traditional construction methods not only accelerates building processes but also enhances working efficiencies globally.Despite its widespread adoption,the performance of industrialized building manufacturing(IBM)can still be optimized,particularly in enhancing time efficiency and reducing costs.This paper explores the integration of Artificial Intelligence(AI)and robotics at IBM to improve efficiency,cost-effectiveness,and material use in off-site assembly.Through a narrative literature review,this study systematically categorizes AI-based Robots(AIRs)applications into four critical stages—Cognition,Communication,Control,and Collab-oration and Coordination,and then investigates their appli-cation in the factory assembly process for industrialized buildings,which is structured into distinct stages:compo-nent preparation,sub-assembly,main assembly,finishing tasks,and quality control.Each stage,from positioning components to the integration of larger modules and subsequent quality inspection,often involves robots or human-robot collaboration to enhance precision and effi-ciency.By examining research from 2014 to 2024,the review highlights the significant improvements AI-based robots have introduced to the construction sector,identifies existing challenges,and outlines future research directions.This comprehensive analysis aims to establish more effi-cient,precise,and tailored construction processes,paving the way for advanced IBM.
文摘This paper presents a new Wireless Power Transfer(WPT)approach by aligning the phases of a group of spatially distributed Radio Frequency(RF)transmitters(TX)at the target receiver(RX)device.Our approach can transfer energy over tens of meters and even to targets blocked by obstacles.Compared to popular beamforming based WPTs,our approach leads to a drastically different energy density distribution:the energy density at the target receiver is much higher than the energy density at other locations.Due to this unique energy distribution pattern,our approach offers a safer WPT solution,which can be potentially scaled up to ship a higher level of energy over longer distances.Specifically,we model the energy density distribution and prove that our proposed system can create a high energy peak exactly at the target receiver.Then we conduct detailed simulation studies to investigate how the actual energy distribution is impacted by various important system parameters,including number/topology of transmitters,transmitter antenna directionality,the distance between receiver and transmitters,and environmental multipath.Finally,we build an actual prototype with 17 N210 and 4 B210 Universal Software Radio Peripheral(USRP)nodes,through which we validate the salient features and performance promises of the proposed system.
文摘As renewable energy is becoming the major re-source in future power grids,the weather and climate can have a higher impact on grid reliability.Transmission expansion planning(TEP)has the potential to reinforce the power trans-fer capability of a transmission network for climate-impacted power grids.In this paper,we propose a systematic TEP proce-dure for renewable-energy-dominated power grids considering climate impact(CI).Particularly,this paper develops an im-proved model for TEP considering climate impact(TEP-CI)and evaluates the reliability of power grid with the obtained transmission investment plan.Firstly,we create climate-impact-ed spatio-temporal future power grid data to facilitate the study of TEP-CI,which include the future climate-dependent re-newable power generation as well as the dynamic line rating profiles of the Texas 123-bus backbone transmission(TX-123BT)system.Secondly,the TEP-CI model is proposed,which considers the variation in renewable power generation and dy-namic line rating,and the investment plan for future TX-123BT system is obtained.Thirdly,a customized security-con-strained unit commitment(SCUC)is presented specifically for climate-impacted power grids.The reliability of future power grid in various investment scenarios is analyzed based on the daily operation conditions from SCUC simulations.The whole procedure presented in this paper enables numerical studies on power grid planning considering climate impact.It can also serve as a benchmark for other studies of the TEP-CI model and its performance evaluation.
