A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl...A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles （VSNPs） as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels （H gels） and a series of poly（acrylamide-co-dimethylacrylamide） （P（AM-co-DMAA）） NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles （SNPs）. Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P（AM-co-DMAA） NCP gels, the P（AM-co- DMAA） chains are grafted on VSNPs and the polydimethylacrylamide （PDMAA） only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P（AM-co-DMAA） NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.展开更多
Flatness is one of the most important criterion factors to evaluate the quality of the steel strip.To improve the strip's flatness quality,the most frequently used methodology is to employ the closed-loop automati...Flatness is one of the most important criterion factors to evaluate the quality of the steel strip.To improve the strip's flatness quality,the most frequently used methodology is to employ the closed-loop automatic shape control system.However,in the shape control system,the shape-meter is always installed at the down way of the exit of the cold rolling mill and can not sense the changes of the strip flatness in the rolling gap directly.This kind of installation results in the delay of the feedback in the control system.Therefore,the stability and response performance of the system are strongly affected by the delay.At present,there is still no mature way to design controllers for systems with time delay.Although the conventional PID controller used in most practical applications has the capability to compensate the delay,the effect of the compensation is limited,especially for the systems with long time delay.Smith predictor,as a compensator for solving this problem,is now widely used in industry systems.However,the request of highly precise model of the system and the poor adaptive performance to the changes of related parameters limit the application of the Smith predictor in practice.In order to overcome the drawbacks of the Smith predictor,a new Smith predictor based on single neural network PID(SNN-PID)is proposed.Because the single neural network is employed into the Smith predictor to improve the controller's self-adaptability,the adaptive capability to the varying parameters of the system is improved.Meanwhile,for the purpose of solving the problems such as time-consuming and complicated calculation of the neural networks in real time,the learning coefficient of neural network is divided into several stages as usually done in expert control system.Therefore,the control system can obtain fast response due to the improved calculation speed of the neural networks.In order to validate the performance of the proposed controller,the experiment is conducted on the shape control system in a 300 mm four-high reversing cold rolling mill.The experimental results show that the SNN-PID with Smith predictor controller can effectively compensate the delay effects and achieve better control performance than the conventional PID controller.展开更多
Study of gene expression has been arguably the most active research field in functional genomics.Over the last two decades,various high-throughput technologies,from gene expression microarray to RNA-seq,have been wide...Study of gene expression has been arguably the most active research field in functional genomics.Over the last two decades,various high-throughput technologies,from gene expression microarray to RNA-seq,have been widely applied to the wholegenome profiling of gene expression.The commonality of these experiments is that they measure the gene expression levels of"bulk"sample,which pools a large number(often in the scale of millions)of cells,and thus the measurements reflect the average expression展开更多
In this letter, we present a novel integrated feature that incorporates traditional parameters, and adopt a parallel cascading fashion network Haze Net for enhancing image quality. Our unified feature is a complete in...In this letter, we present a novel integrated feature that incorporates traditional parameters, and adopt a parallel cascading fashion network Haze Net for enhancing image quality. Our unified feature is a complete integration, and its role is to directly describe the effects of haze. In Haze Net, we design two separate structures including backbone and auxiliary networks to extract feature map. Backbone network is responsible for extracting high-level feature map, and low-level feature learned by the auxiliary network can be interpreted as fine-grained feature. After cascading two features with different accuracy, final performance can be effectively improved. Extensive experimental results on both synthetic datasets and real-world images prove the superiority of the proposed method, and demonstrate more favorable performance compared with the existing state-of-art methods.展开更多
In this paper, we propose a new spatial-multiplexing(SM) scheme employing an orthogonal precoder over Rayleigh-fading channels for an erasure event in single frequency networks(SFN). To optimize the precoder, the aver...In this paper, we propose a new spatial-multiplexing(SM) scheme employing an orthogonal precoder over Rayleigh-fading channels for an erasure event in single frequency networks(SFN). To optimize the precoder, the average bit error rate(BER) is evaluated and minimized through a mathematical analysis. Compared to an ordinary SM, the proposed scheme guarantees identical BER performance under non-erasure fading channels and achieves a greatly improved performance under erasure fading channels, especially for a higher erasure-ratio and SNR values. This improvement is mainly due to the increase in the diversity gain incurred by the optimized precoder over the erasure event. We also compare the performance of the proposed SM to that of the conventional constellation-rotation(CR) scheme applied to the single antenna SFN systems. The results of a computer simulation show that the performance of the new scheme is more effective than that of a conventional CR across all simulation cases.展开更多
The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network...The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network (SFN) mode, and the unicast services are delivered with point-to-point (PTP) mode. To minimize the demanded radio resources for multicast services in the LTE, a novel mode switch (MS) between SFN and PTP for multicast services is proposed. MS takes into account PTP mode for multicast services and the switch is based on the handover threshold. To solve the minimization problem, MS adapts the handover threshold with the difference in the demanded radio resources between SFN mode and PTP mode for multicast services. The simulation results show that the proposed MS achieves less demanded radio resources than SFN mode for all the multicast services.展开更多
Organic light-emitting diodes(OLEDs)used in virtual and augmented reality displays require micrometer-scale red-green-blue(RGB)pixel patterns in the emissive layer(EML).However,conventional patterning methods based on...Organic light-emitting diodes(OLEDs)used in virtual and augmented reality displays require micrometer-scale red-green-blue(RGB)pixel patterns in the emissive layer(EML).However,conventional patterning methods based on evaporation and shadow masks can only produce patterns larger than tens of micrometers owing to the geometric constraint of the mask.Herein,an indirect method for photopatterning solution-processed OLED EMLs is proposed,which can be used to form micrometer-scale RGB pixel patterns without involving direct exposure to UV radiation or harsh etching processes on EMLs.EMLs can be patterned byⅰ)forming a sacrificial photoresist(PR)pattern,ⅱ)spin-coating an EML film,ⅲ)converting the EML film into a single-phase network(SPN)structure by crosslinking vinylbenzyl-group-appended hosts and dopants at a low temperature,andⅳ)stripping the pre-formed PR pattern.Furthermore,repeating the process thrice results in the formation of RGB EML patterns.During the repeated process,the sacrificial PR pattern serves as a protective layer for the underlying EML pattern,effectively preventing the EML pattern from being exposed to solutions in subsequent processes.Using a conventional photolithography setup,we produced sets of RGB EML patterns with densities exceeding 3000 patterns/in.,which indicated the potential of the method for industrial use.展开更多
The single frequency network (SFN) can provide a multimedia broadcast multicast service over a large coverage area. However, the application of SFN is still restricted by a large amount of feedback. Therefore, we prop...The single frequency network (SFN) can provide a multimedia broadcast multicast service over a large coverage area. However, the application of SFN is still restricted by a large amount of feedback. Therefore, we propose a multicast resource allocation scheme based on limited feedback to maximize the total rate while guaranteeing the quality of service (QoS) requirement of real-time services. In this scheme, we design a user feedback control algorithm to effectively reduce feedback load. The algorithm determines to which base stations the users should report channel state information. We then formulate a joint subcarrier and power allocation issue and find that it has high complexity. Hence, we first distribute subcarriers under the assumption of equal power and develop a proportional allocation strategy to achieve a tradeoff between fairness and QoS. Next, an iterative water-filling power allocation is proposed to fully utilize the limited power. To further decrease complexity, a power iterative scheme is introduced. Simulation results show that the proposed scheme significantly improves system performance while reducing 68% of the feedback overhead. In addition, the power iterative strategy is suitable in practice due to low complexity.展开更多
Extreme learning machine(ELM)allows for fast learning and better generalization performance than conventional gradient-based learning.However,the possible inclusion of non-optimal weight and bias due to random selecti...Extreme learning machine(ELM)allows for fast learning and better generalization performance than conventional gradient-based learning.However,the possible inclusion of non-optimal weight and bias due to random selection and the need for more hidden neurons adversely influence network usability.Further,choosing the optimal number of hidden nodes for a network usually requires intensive human intervention,which may lead to an ill-conditioned situation.In this context,chemical reaction optimization(CRO)is a meta-heuristic paradigm with increased success in a large number of application areas.It is characterized by faster convergence capability and requires fewer tunable parameters.This study develops a learning framework combining the advantages of ELM and CRO,called extreme learning with chemical reaction optimization(ELCRO).ELCRO simultaneously optimizes the weight and bias vector and number of hidden neurons of a single layer feed-forward neural network without compromising prediction accuracy.We evaluate its performance by predicting the daily volatility and closing prices of BSE indices.Additionally,its performance is compared with three other similarly developed models—ELM based on particle swarm optimization,genetic algorithm,and gradient descent—and find the performance of the proposed algorithm superior.Wilcoxon signed-rank and Diebold–Mariano tests are then conducted to verify the statistical significance of the proposed model.Hence,this model can be used as a promising tool for financial forecasting.展开更多
This paper aims to propose a framework for manifold regularization(MR) based distributed semi-supervised learning(DSSL) using single layer feed-forward neural network(SLFNN). The proposed framework, denoted as DSSL-SL...This paper aims to propose a framework for manifold regularization(MR) based distributed semi-supervised learning(DSSL) using single layer feed-forward neural network(SLFNN). The proposed framework, denoted as DSSL-SLFNN is based on the SLFNN, MR framework, and distributed optimization strategy. Then, a series of algorithms are derived to solve DSSL problems. In DSSL problems, data consisting of labeled and unlabeled samples are distributed over a communication network, where each node has only access to its own data and can only communicate with its neighbors. In some scenarios, DSSL problems cannot be solved by centralized algorithms. According to the DSSL-SLFNN framework, each node over the communication network exchanges the initial parameters of the SLFNN with the same basis functions for semi-supervised learning(SSL). All nodes calculate the global optimal coefficients of the SLFNN by using distributed datasets and local updates. During the learning process, each node only exchanges local coefficients with its neighbors rather than raw data. It means that DSSL-SLFNN based algorithms work in a fully distributed fashion and are privacy preserving methods. Finally, several simulations are presented to show the efficiency of the proposed framework and the derived algorithms.展开更多
Motivated by the autopilot of an unmanned aerial vehicle（UAV） with a wide flight envelope span experiencing large parametric variations in the presence of uncertainties, a fuzzy adaptive tracking controller（FATC） ...Motivated by the autopilot of an unmanned aerial vehicle（UAV） with a wide flight envelope span experiencing large parametric variations in the presence of uncertainties, a fuzzy adaptive tracking controller（FATC） is proposed. The controller consists of a fuzzy baseline controller and an adaptive increment, and the main highlight is that the fuzzy baseline controller and adaptation laws are both based on the fuzzy multiple Lyapunov function approach, which helps to reduce the conservatism for the large envelope and guarantees satisfactory tracking performances with strong robustness simultaneously within the whole envelope. The constraint condition of the fuzzy baseline controller is provided in the form of linear matrix inequality（LMI）, and it specifies the satisfactory tracking performances in the absence of uncertainties. The adaptive increment ensures the uniformly ultimately bounded（UUB） predication errors to recover satisfactory responses in the presence of uncertainties. Simulation results show that the proposed controller helps to achieve high-accuracy tracking of airspeed and altitude desirable commands with strong robustness to uncertainties throughout the entire flight envelope.展开更多
A new hydraulic actuator-hydraulic muscle （HM） is described, and the actuator＇s features and applications are analyzed, then a position servocontrol system in which HM is main actuator is set up. The mathematical m...A new hydraulic actuator-hydraulic muscle （HM） is described, and the actuator＇s features and applications are analyzed, then a position servocontrol system in which HM is main actuator is set up. The mathematical model of the system is built up and several control strategies are discussed. Based on the mathematical model, simulation research and experimental investigation with subsection PID control, neural network self-adaptive PID control and single neuron self-adaptive PID control adopted respectively are carried out, and the results indicate that compared with PID control, neural network self-adaptive PID control and single neuron self-adaptive PID control don＇t need controlled system＇s accurate model and have fast response, high control accuracy and strong robustness, they are very suitable for HM position servo control system.展开更多
Today, just by activating a button on the display panel of a total station, one can measure horizontal and vertical angles or calculate distances and coordinates of points. For this reason, it has become necessary to ...Today, just by activating a button on the display panel of a total station, one can measure horizontal and vertical angles or calculate distances and coordinates of points. For this reason, it has become necessary to improve the check of a total station in order to respond to its contemporary way of use. The aim of this research is to create a new method for checking total stations using only one check--field, in a different way of the today＇s standards. The basic principle, of the comparison of an instrument＇s measurements to those of another instrument with higher accuracy, is implemented into a mathematical model such as the adjustment of an indoor geodetic network. Thus, the check of the proper function of a total station is applied. An a-priori calculation Of^o of the network＇s adjustment can be calculated by modeling the uncertainties using statistical methods as the random number generators by means of the Monte Carlo method. The prospective ao can then be compared to the a-posteriori ao provided by the adjustment of the measurements which are carried out by using the total station under check.展开更多
To avoid the traffic congestion in long term evolution （LTE） networks, a min-max load balancing （LB） scheme is proposed to minimize the demanded radio resources of the maximum loaded cell. For the mixed multicast ...To avoid the traffic congestion in long term evolution （LTE） networks, a min-max load balancing （LB） scheme is proposed to minimize the demanded radio resources of the maximum loaded cell. For the mixed multicast and unicast services, multicast services are transmitted by single frequency network （SFN） mode and unicast services are delivered with point-to-point （PTP） mode. The rain-max LB takes into account point-to-multipoint （PTM） mode for multicast services and selects the proper transmission mode between SFN and PTM for each multicast service to minimize the demanded radio resources of the maximum loaded cell. Based on the solution of this minimization problem, if the maximum loaded cell does not overload, the min-max LB will change PTM mode into SFN mode for mulficast services to achieve high quality of service （QoS）. Simulation results show that the proposed miu-max LB scheme requires less radio resources from the maximum loaded cell than SFN mode for all multicast services.展开更多
Vehicle detection in dim light has always been a challenging task.In addition to the unavoidable noise,the uneven spatial distribution of light and dark due to vehicle lights and street lamps can further make the prob...Vehicle detection in dim light has always been a challenging task.In addition to the unavoidable noise,the uneven spatial distribution of light and dark due to vehicle lights and street lamps can further make the problem more difficult.Conventional image enhancement methods may produce over smoothing or over exposure problems,causing irreversible information loss to the vehicle targets to be subsequently detected.Therefore,we propose a multi-exposure generation and fusion network.In the multi-exposure generation network,we employ a single gated convolutional recurrent network with two-stream progressive exposure input to generate intermediate images with gradually increasing exposure,which are provided to the multi-exposure fusion network after a spatial attention mechanism.Then,a pre-trained vehicle detection model in normal light is used as the basis of the fusion network,and the two models are connected using the convolutional kernel channel dimension expansion technique.This allows the fusion module to provide vehicle detection information,which can be used to guide the generation network tofine-tune the parameters and thus complete end-to-end enhancement and training.By coupling the two parts,we can achieve detail interaction and feature fusion under different lighting conditions.Our experimental results demonstrate that our proposed method is better than the state-of-the-art detection methods after image luminance enhancement on the ODDS dataset.展开更多
Currently,development of a single network hydrogel with a high fracture toughness in swelling equilibrium remains challenging.In this work,a novel T-shaped trifunctional crosslinker(T-NAGAX)with dual vinyl on the back...Currently,development of a single network hydrogel with a high fracture toughness in swelling equilibrium remains challenging.In this work,a novel T-shaped trifunctional crosslinker(T-NAGAX)with dual vinyl on the backbone and dual amide group on the side chain is synthesized by Michael addition and acylation.The T-NAGAX is used to prepare chemically crosslinked hydrogel by one-pot photo-initiated polymerization.The resulting single network hydrogels of representative polyacrylamide(PAAm),poly(N-acryloyl 2-glycine)(PACG),and poly(N-isopropyl acrylamide)(PNIPAM)crosslinked with T-NAGAX with additional hydrogen-bonds exhibit much better fracture toughness than that of the corresponding hydrogels crosslinked by N,N'-methylene bisacrylamide,a conventional crosslinker;higher mechanical strengths are observed in the T-NAGAX crosslinked hydrogels.These hydrogels are promising to be exploited as load-bearing soft tissue substitutes.This T-NAGAX crosslinker can be expanded to toughen various types of hydrogels.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.21474058 and 51633003)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(No.LK1404)+1 种基金Tsinghua University Scientific Research Project(No.2014Z22069)State Key Laboratory of Organic-Inorganic Composites,Beijing University of Chemical Technology(No.OIC-201601006)
文摘A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles （VSNPs） as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels （H gels） and a series of poly（acrylamide-co-dimethylacrylamide） （P（AM-co-DMAA）） NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles （SNPs）. Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P（AM-co-DMAA） NCP gels, the P（AM-co- DMAA） chains are grafted on VSNPs and the polydimethylacrylamide （PDMAA） only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P（AM-co-DMAA） NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.
基金supported by National Natural Science Foundation of China(Grant No.604740044)Hebei Provincial Natural Science Foundation of China(Grant No.E2004000221)
文摘Flatness is one of the most important criterion factors to evaluate the quality of the steel strip.To improve the strip's flatness quality,the most frequently used methodology is to employ the closed-loop automatic shape control system.However,in the shape control system,the shape-meter is always installed at the down way of the exit of the cold rolling mill and can not sense the changes of the strip flatness in the rolling gap directly.This kind of installation results in the delay of the feedback in the control system.Therefore,the stability and response performance of the system are strongly affected by the delay.At present,there is still no mature way to design controllers for systems with time delay.Although the conventional PID controller used in most practical applications has the capability to compensate the delay,the effect of the compensation is limited,especially for the systems with long time delay.Smith predictor,as a compensator for solving this problem,is now widely used in industry systems.However,the request of highly precise model of the system and the poor adaptive performance to the changes of related parameters limit the application of the Smith predictor in practice.In order to overcome the drawbacks of the Smith predictor,a new Smith predictor based on single neural network PID(SNN-PID)is proposed.Because the single neural network is employed into the Smith predictor to improve the controller's self-adaptability,the adaptive capability to the varying parameters of the system is improved.Meanwhile,for the purpose of solving the problems such as time-consuming and complicated calculation of the neural networks in real time,the learning coefficient of neural network is divided into several stages as usually done in expert control system.Therefore,the control system can obtain fast response due to the improved calculation speed of the neural networks.In order to validate the performance of the proposed controller,the experiment is conducted on the shape control system in a 300 mm four-high reversing cold rolling mill.The experimental results show that the SNN-PID with Smith predictor controller can effectively compensate the delay effects and achieve better control performance than the conventional PID controller.
基金partially supported by NIH grants (2U19AI090023,5P30AI50409,and R01GM122083)
文摘Study of gene expression has been arguably the most active research field in functional genomics.Over the last two decades,various high-throughput technologies,from gene expression microarray to RNA-seq,have been widely applied to the wholegenome profiling of gene expression.The commonality of these experiments is that they measure the gene expression levels of"bulk"sample,which pools a large number(often in the scale of millions)of cells,and thus the measurements reflect the average expression
基金supported by the National Natural Science Foundation of China (No.61561030)the Gansu Provincial F inance Department (No.214138)。
文摘In this letter, we present a novel integrated feature that incorporates traditional parameters, and adopt a parallel cascading fashion network Haze Net for enhancing image quality. Our unified feature is a complete integration, and its role is to directly describe the effects of haze. In Haze Net, we design two separate structures including backbone and auxiliary networks to extract feature map. Backbone network is responsible for extracting high-level feature map, and low-level feature learned by the auxiliary network can be interpreted as fine-grained feature. After cascading two features with different accuracy, final performance can be effectively improved. Extensive experimental results on both synthetic datasets and real-world images prove the superiority of the proposed method, and demonstrate more favorable performance compared with the existing state-of-art methods.
文摘In this paper, we propose a new spatial-multiplexing(SM) scheme employing an orthogonal precoder over Rayleigh-fading channels for an erasure event in single frequency networks(SFN). To optimize the precoder, the average bit error rate(BER) is evaluated and minimized through a mathematical analysis. Compared to an ordinary SM, the proposed scheme guarantees identical BER performance under non-erasure fading channels and achieves a greatly improved performance under erasure fading channels, especially for a higher erasure-ratio and SNR values. This improvement is mainly due to the increase in the diversity gain incurred by the optimized precoder over the erasure event. We also compare the performance of the proposed SM to that of the conventional constellation-rotation(CR) scheme applied to the single antenna SFN systems. The results of a computer simulation show that the performance of the new scheme is more effective than that of a conventional CR across all simulation cases.
基金Sponsored by the National Key Technology R&D Program of China ( Grant No. 2010ZX03003-001-01)Fundamental Research Funds for the Central Universities
文摘The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network (SFN) mode, and the unicast services are delivered with point-to-point (PTP) mode. To minimize the demanded radio resources for multicast services in the LTE, a novel mode switch (MS) between SFN and PTP for multicast services is proposed. MS takes into account PTP mode for multicast services and the switch is based on the handover threshold. To solve the minimization problem, MS adapts the handover threshold with the difference in the demanded radio resources between SFN mode and PTP mode for multicast services. The simulation results show that the proposed MS achieves less demanded radio resources than SFN mode for all the multicast services.
基金supported by the National R&D Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(NRF-2023R1A2C3006550,2021R1A2C2008332,and RS-2024-00445116)。
文摘Organic light-emitting diodes(OLEDs)used in virtual and augmented reality displays require micrometer-scale red-green-blue(RGB)pixel patterns in the emissive layer(EML).However,conventional patterning methods based on evaporation and shadow masks can only produce patterns larger than tens of micrometers owing to the geometric constraint of the mask.Herein,an indirect method for photopatterning solution-processed OLED EMLs is proposed,which can be used to form micrometer-scale RGB pixel patterns without involving direct exposure to UV radiation or harsh etching processes on EMLs.EMLs can be patterned byⅰ)forming a sacrificial photoresist(PR)pattern,ⅱ)spin-coating an EML film,ⅲ)converting the EML film into a single-phase network(SPN)structure by crosslinking vinylbenzyl-group-appended hosts and dopants at a low temperature,andⅳ)stripping the pre-formed PR pattern.Furthermore,repeating the process thrice results in the formation of RGB EML patterns.During the repeated process,the sacrificial PR pattern serves as a protective layer for the underlying EML pattern,effectively preventing the EML pattern from being exposed to solutions in subsequent processes.Using a conventional photolithography setup,we produced sets of RGB EML patterns with densities exceeding 3000 patterns/in.,which indicated the potential of the method for industrial use.
基金supported by the National Natural Science Foundation of China (Nos. 60972076 and 61072052)the National Science and Technology Major Project, China (No. 2010ZX03003-004-03)
文摘The single frequency network (SFN) can provide a multimedia broadcast multicast service over a large coverage area. However, the application of SFN is still restricted by a large amount of feedback. Therefore, we propose a multicast resource allocation scheme based on limited feedback to maximize the total rate while guaranteeing the quality of service (QoS) requirement of real-time services. In this scheme, we design a user feedback control algorithm to effectively reduce feedback load. The algorithm determines to which base stations the users should report channel state information. We then formulate a joint subcarrier and power allocation issue and find that it has high complexity. Hence, we first distribute subcarriers under the assumption of equal power and develop a proportional allocation strategy to achieve a tradeoff between fairness and QoS. Next, an iterative water-filling power allocation is proposed to fully utilize the limited power. To further decrease complexity, a power iterative scheme is introduced. Simulation results show that the proposed scheme significantly improves system performance while reducing 68% of the feedback overhead. In addition, the power iterative strategy is suitable in practice due to low complexity.
文摘Extreme learning machine(ELM)allows for fast learning and better generalization performance than conventional gradient-based learning.However,the possible inclusion of non-optimal weight and bias due to random selection and the need for more hidden neurons adversely influence network usability.Further,choosing the optimal number of hidden nodes for a network usually requires intensive human intervention,which may lead to an ill-conditioned situation.In this context,chemical reaction optimization(CRO)is a meta-heuristic paradigm with increased success in a large number of application areas.It is characterized by faster convergence capability and requires fewer tunable parameters.This study develops a learning framework combining the advantages of ELM and CRO,called extreme learning with chemical reaction optimization(ELCRO).ELCRO simultaneously optimizes the weight and bias vector and number of hidden neurons of a single layer feed-forward neural network without compromising prediction accuracy.We evaluate its performance by predicting the daily volatility and closing prices of BSE indices.Additionally,its performance is compared with three other similarly developed models—ELM based on particle swarm optimization,genetic algorithm,and gradient descent—and find the performance of the proposed algorithm superior.Wilcoxon signed-rank and Diebold–Mariano tests are then conducted to verify the statistical significance of the proposed model.Hence,this model can be used as a promising tool for financial forecasting.
基金supported by National Natural Science Foundation of China (Nos. 61877047, 61877046, 62106186 and 62063031)the Fundamental Research Funds for the Central Universities (Nos. JB210701 and JB210718)。
文摘This paper aims to propose a framework for manifold regularization(MR) based distributed semi-supervised learning(DSSL) using single layer feed-forward neural network(SLFNN). The proposed framework, denoted as DSSL-SLFNN is based on the SLFNN, MR framework, and distributed optimization strategy. Then, a series of algorithms are derived to solve DSSL problems. In DSSL problems, data consisting of labeled and unlabeled samples are distributed over a communication network, where each node has only access to its own data and can only communicate with its neighbors. In some scenarios, DSSL problems cannot be solved by centralized algorithms. According to the DSSL-SLFNN framework, each node over the communication network exchanges the initial parameters of the SLFNN with the same basis functions for semi-supervised learning(SSL). All nodes calculate the global optimal coefficients of the SLFNN by using distributed datasets and local updates. During the learning process, each node only exchanges local coefficients with its neighbors rather than raw data. It means that DSSL-SLFNN based algorithms work in a fully distributed fashion and are privacy preserving methods. Finally, several simulations are presented to show the efficiency of the proposed framework and the derived algorithms.
文摘Motivated by the autopilot of an unmanned aerial vehicle（UAV） with a wide flight envelope span experiencing large parametric variations in the presence of uncertainties, a fuzzy adaptive tracking controller（FATC） is proposed. The controller consists of a fuzzy baseline controller and an adaptive increment, and the main highlight is that the fuzzy baseline controller and adaptation laws are both based on the fuzzy multiple Lyapunov function approach, which helps to reduce the conservatism for the large envelope and guarantees satisfactory tracking performances with strong robustness simultaneously within the whole envelope. The constraint condition of the fuzzy baseline controller is provided in the form of linear matrix inequality（LMI）, and it specifies the satisfactory tracking performances in the absence of uncertainties. The adaptive increment ensures the uniformly ultimately bounded（UUB） predication errors to recover satisfactory responses in the presence of uncertainties. Simulation results show that the proposed controller helps to achieve high-accuracy tracking of airspeed and altitude desirable commands with strong robustness to uncertainties throughout the entire flight envelope.
文摘A new hydraulic actuator-hydraulic muscle （HM） is described, and the actuator＇s features and applications are analyzed, then a position servocontrol system in which HM is main actuator is set up. The mathematical model of the system is built up and several control strategies are discussed. Based on the mathematical model, simulation research and experimental investigation with subsection PID control, neural network self-adaptive PID control and single neuron self-adaptive PID control adopted respectively are carried out, and the results indicate that compared with PID control, neural network self-adaptive PID control and single neuron self-adaptive PID control don＇t need controlled system＇s accurate model and have fast response, high control accuracy and strong robustness, they are very suitable for HM position servo control system.
文摘Today, just by activating a button on the display panel of a total station, one can measure horizontal and vertical angles or calculate distances and coordinates of points. For this reason, it has become necessary to improve the check of a total station in order to respond to its contemporary way of use. The aim of this research is to create a new method for checking total stations using only one check--field, in a different way of the today＇s standards. The basic principle, of the comparison of an instrument＇s measurements to those of another instrument with higher accuracy, is implemented into a mathematical model such as the adjustment of an indoor geodetic network. Thus, the check of the proper function of a total station is applied. An a-priori calculation Of^o of the network＇s adjustment can be calculated by modeling the uncertainties using statistical methods as the random number generators by means of the Monte Carlo method. The prospective ao can then be compared to the a-posteriori ao provided by the adjustment of the measurements which are carried out by using the total station under check.
基金supported by the National Science and Technology Major Project (2010ZX03003-001-01)Fundamental Research Funds for the Central Universities
文摘To avoid the traffic congestion in long term evolution （LTE） networks, a min-max load balancing （LB） scheme is proposed to minimize the demanded radio resources of the maximum loaded cell. For the mixed multicast and unicast services, multicast services are transmitted by single frequency network （SFN） mode and unicast services are delivered with point-to-point （PTP） mode. The rain-max LB takes into account point-to-multipoint （PTM） mode for multicast services and selects the proper transmission mode between SFN and PTM for each multicast service to minimize the demanded radio resources of the maximum loaded cell. Based on the solution of this minimization problem, if the maximum loaded cell does not overload, the min-max LB will change PTM mode into SFN mode for mulficast services to achieve high quality of service （QoS）. Simulation results show that the proposed miu-max LB scheme requires less radio resources from the maximum loaded cell than SFN mode for all multicast services.
基金supported in part by the Science and Technology Innovation foundation(No.JSGG20210802152811033).
文摘Vehicle detection in dim light has always been a challenging task.In addition to the unavoidable noise,the uneven spatial distribution of light and dark due to vehicle lights and street lamps can further make the problem more difficult.Conventional image enhancement methods may produce over smoothing or over exposure problems,causing irreversible information loss to the vehicle targets to be subsequently detected.Therefore,we propose a multi-exposure generation and fusion network.In the multi-exposure generation network,we employ a single gated convolutional recurrent network with two-stream progressive exposure input to generate intermediate images with gradually increasing exposure,which are provided to the multi-exposure fusion network after a spatial attention mechanism.Then,a pre-trained vehicle detection model in normal light is used as the basis of the fusion network,and the two models are connected using the convolutional kernel channel dimension expansion technique.This allows the fusion module to provide vehicle detection information,which can be used to guide the generation network tofine-tune the parameters and thus complete end-to-end enhancement and training.By coupling the two parts,we can achieve detail interaction and feature fusion under different lighting conditions.Our experimental results demonstrate that our proposed method is better than the state-of-the-art detection methods after image luminance enhancement on the ODDS dataset.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0703100)the National Natural Science Foundation of China(Grant No.51733006)。
文摘Currently,development of a single network hydrogel with a high fracture toughness in swelling equilibrium remains challenging.In this work,a novel T-shaped trifunctional crosslinker(T-NAGAX)with dual vinyl on the backbone and dual amide group on the side chain is synthesized by Michael addition and acylation.The T-NAGAX is used to prepare chemically crosslinked hydrogel by one-pot photo-initiated polymerization.The resulting single network hydrogels of representative polyacrylamide(PAAm),poly(N-acryloyl 2-glycine)(PACG),and poly(N-isopropyl acrylamide)(PNIPAM)crosslinked with T-NAGAX with additional hydrogen-bonds exhibit much better fracture toughness than that of the corresponding hydrogels crosslinked by N,N'-methylene bisacrylamide,a conventional crosslinker;higher mechanical strengths are observed in the T-NAGAX crosslinked hydrogels.These hydrogels are promising to be exploited as load-bearing soft tissue substitutes.This T-NAGAX crosslinker can be expanded to toughen various types of hydrogels.
