In this paper, a Non-Ablative Thermal Protection System(NATPS) with the spiked body and the opposing jet combined configuration is proposed to reduce the aerodynamic heating of the hypersonic vehicle, and the coupled ...In this paper, a Non-Ablative Thermal Protection System(NATPS) with the spiked body and the opposing jet combined configuration is proposed to reduce the aerodynamic heating of the hypersonic vehicle, and the coupled fluid-thermal numerical analysis is performed to study the thermal control performance of the NATPS. The results show that the spiked body pushes the bow shock away from the protected structure and thus reduces the shock intensity and the wall heat flux. In addition, the low temperature gas of the opposing jet separates the high temperature gas behind the shock from the nose cone of the spiked body, ensuring the non-ablative property of the spiked body. Therefore, the NATPS reduces the aerodynamic heating by the reconfiguration of the flow field, and the thermal control efficiency of the system is better than the Thermal Protection System(TPS) with the single spiked body and the single opposing jet. The influencing factors of the NATPS are analyzed. Both increasing the length of the spiked body and reducing the total temperature of the opposing jet can improve the thermal control performance of the NATPS and the nonablative property of the spiked body. However, increasing the heat conductivity coefficient of the spiked body can enhance benefit the non-ablative property of the spiked body, but has little influence on the thermal control performance of the NATPS.展开更多
By adopting the CFD based approach,the hypersonic flow nature is investigated under a Free-stream Mach number of 6 for two distinct re-entry configurations;namely,a spiked conical-nosed body,and a spiked T-shaped blun...By adopting the CFD based approach,the hypersonic flow nature is investigated under a Free-stream Mach number of 6 for two distinct re-entry configurations;namely,a spiked conical-nosed body,and a spiked T-shaped blunt-nosed body,each coupled with counterflow jets.A high-fidelity structured mesh and the SST k-omega Turbulence model within the Ansys Fluent framework are employed to capture flow phenomena like bow shock detachment,recirculation,and wake formation with finer precision.The analysis is performed on vital performance parameters such as aerodynamic drag,surface pressure and temperature distributions,and the effect of counterflow jets on shock stand-off distance and thermal load reduction.We find results indicating drag reduction of 52%by the conical blunt-nosed configuration compared to the T-Shape nose configuration and an increase in shock stand-off distance by 0.0175.Moreover,counterflow jets reduce the surface temperature by a maximum of 300 K at critical forebody regions,while the total pressure recovery improves by 50%.These findings affirm that nose shape is a critical parameter influencing the hypersonic flow control and thus offers new perspectives for the design optimization,with T-shaped configuration providing improved thermal protection and aerodynamic efficiency.展开更多
基于动态Spike and Slab先验,结合删失时间序列的似然函数,构建了适用于删失时间序列数据的贝叶斯动态变量选择回归模型.为处理计算问题,采用了EM算法进行求解,从而能够快速获得模型参数估计与变量选择结果.通过模拟研究验证了该方法的...基于动态Spike and Slab先验,结合删失时间序列的似然函数,构建了适用于删失时间序列数据的贝叶斯动态变量选择回归模型.为处理计算问题,采用了EM算法进行求解,从而能够快速获得模型参数估计与变量选择结果.通过模拟研究验证了该方法的有效性,并将其应用于实际磷浓度数据分析中.展开更多
Improved yield potential is the goal of barley domestication and cultivation.During this process,two-and six-rowed barley types emerged and have been utilised in breeding and production.The six-rowed type could produc...Improved yield potential is the goal of barley domestication and cultivation.During this process,two-and six-rowed barley types emerged and have been utilised in breeding and production.The six-rowed type could produce three times as many grains as its ancestral two-rowed forms,thus dominating barley cultivation for thousands of years.The deficiens form of the two-rowed type,characterised by extremely suppressed lateral spikelets,has gained dominance over the past few decades in barley-growing regions worldwide.We hypothesised that the absence of lateral spikelets in deficiens barley affects spike architecture and spike-related traits,contributing to its superior yield potential of deficiens barley cultivation.Currently,a deficiens barley variety,RGT Planet,is the most popular barley variety in the world.In this study,we used two F_(2) populations derived from crossing RGT Planet with two canonical two-rowed barley and identified the functional allele Vrs1.t1 associated with deficiens morphology.We observed that the Vrs1.t1 allele may contribute to high yield potential by optimising spike architecture through increased spikelet length,grain number,and grain size.Phylogenetic analysis suggests that the deficiens mutation was likely present from the early stages of barley cultivation in the Fertile Crescent and spread to Ethiopia and beyond with agricultural expansion.We conclude that the ancient deficiens allele Vrs1.t1 has been a critical driver for the recent success of modern barley improvement by optimising spike architecture.展开更多
When teaching neurology students about epilepsy,selecting appropriate antiseizure medications(ASMs)based on seizure type is a fundamental objective.Carbamazepine(CBZ),a widely used first-line ASM,is effective against ...When teaching neurology students about epilepsy,selecting appropriate antiseizure medications(ASMs)based on seizure type is a fundamental objective.Carbamazepine(CBZ),a widely used first-line ASM,is effective against focal seizures,generalized tonic-clonic seizures,and mixed seizure patterns[1].However,CBZ paradoxically aggravates absence seizures,as demonstrated by increased 36 Hz spike-and-wave discharges(SWDs)in both patients and animal models[2,3].While prior studies implicated altered GABAA receptor function in the thalamic ventrobasal complex[4],the precise mechanisms remained unclear.Recently,an inspiring study published on PNAS by Jang et al.from Stanford University has highlighted the thalamic reticular nucleus(RT)as the key brain region responsible for CBZ's aggravating effect on absence seizures[5].The combination of transgenic mouse models,optogenetics,and detailed electrophysiology in the original study provided exceptional precision in probing mechanistic insights,which greatly strengthens the conclusions.展开更多
Background:Beverages play a positive role in a balanced diet.Beverages can provide an enjoyable and refreshing mind to reach a particular target.In beverages,date-rape drugs,such as Rohypnol,gamma-hydroxybutyric acid,...Background:Beverages play a positive role in a balanced diet.Beverages can provide an enjoyable and refreshing mind to reach a particular target.In beverages,date-rape drugs,such as Rohypnol,gamma-hydroxybutyric acid,and ketamine,were usually added to make victims to become weak,confused,unconscious,and vulnerable.Aims and Objectives:The aims and objectives of the research work are to analyze the beverages,viz.,Sprite,Coca-Cola and Coffee by analytical techniques and to degrade the date-rape drug present in the beverages by photocatalysis using activated carbon as the photocatalyst material.Materials and Methods:The drug(clonazepam)and beverages used in the research work were analyzed using FTIR,UV and HPLC techniques.Results:From the FTIR,in beverages(Sprite and Coca-Cola),the peaks corresponding to C-O and O-H functional groups confirmed the presence of CO_(2)and H_(2)O and in Coffee,the presence ofν_(as)(COC)andνs(COC)vibration bands is found out.The UV-visible analysis confirmed theλ_(max)value for activated carbon as 251 nm.Under visible light and activated carbon photocatalyst,53.57%of drug molecule was degraded from coca cola which was found to be highest than other beverages.The degradation of drug molecule was also confirmed by the reduction in the peak area for a particular retention time through HPLC analysis.Conclusion:Photocatalysis can be effectively used to remove any drug present in the spike drinks.展开更多
Memristors have a synapse-like two-terminal structure and electrical properties,which are widely used in the construc-tion of artificial synapses.However,compared to inorganic materials,organic materials are rarely us...Memristors have a synapse-like two-terminal structure and electrical properties,which are widely used in the construc-tion of artificial synapses.However,compared to inorganic materials,organic materials are rarely used for artificial spiking synapses due to their relatively poor memrisitve performance.Here,for the first time,we present an organic memristor based on an electropolymerized dopamine-based memristive layer.This polydopamine-based memristor demonstrates the improve-ments in key performance,including a low threshold voltage of 0.3 V,a thin thickness of 16 nm,and a high parasitic capaci-tance of about 1μF·mm^(-2).By leveraging these properties in combination with its stable threshold switching behavior,we con-struct a capacitor-free and low-power artificial spiking neuron capable of outputting the oscillation voltage,whose spiking fre-quency increases with the increase of current stimulation analogous to a biological neuron.The experimental results indicate that our artificial spiking neuron holds potential for applications in neuromorphic computing and systems.展开更多
Photonic hardware implementation of spiking neural networks,regarded as a viable potential paradigm for ultra-high speed and energy efficiency computing,leverages spatiotemporal spike encoding and event-driven dynamic...Photonic hardware implementation of spiking neural networks,regarded as a viable potential paradigm for ultra-high speed and energy efficiency computing,leverages spatiotemporal spike encoding and event-driven dynamics to simulate brain-like parallel information processing.Silicon-based microring resonators(MRRs)offer a power efficiency and ultrahigh flexibility scheme to mimic biological neuron,however,their substantial potential for integrated neuromorphic systems remains limited by insufficient exploration of MRR-based spiking digital and analog computation.Here,an all-optical neural dynamics framework,encompassing both excitatory and inhibitory behaviors based on multi-wavelength auxiliary and competition mechanism in an MRR,is proposed numerically.Leveraging multi-wavelength resonance characteristics and wavelength division multiplexing(WDM)technology,a single MRR implements the five fundamental optical digital logic gates:AND,OR,NOT,XNOR and XOR.Besides,the cascading capabilities of MRR-based spiking neurons are demonstrated through multi-level digital logic gates including NAND,NOR,4-input AND,8-input AND,and a full adder,emphasizing their promise for large-scale digital logic networks.Furthermore,an exemplary binary convolution has been achieved by utilizing the proposed MRR-based digital logic operation,illustrating the potential of all-optical binary convolution to compute image gradient magnitudes for edge detection.Such passive photonic neurons and networks promise access to the high transmission speed and low power consumption inherent to optical systems,thus enabling direct hardware-algorithm co-computation and accelerating artificial intelligence.展开更多
Grain yield variation has been associated to variation in grain number per unit area(GN).It has been shown in the last about 40 years that GN is linearly associated to the spike dry weight(SDW)at anthesis in wheat,fac...Grain yield variation has been associated to variation in grain number per unit area(GN).It has been shown in the last about 40 years that GN is linearly associated to the spike dry weight(SDW)at anthesis in wheat,fact that has been useful to understand mechanistically potential grain yield.Fruiting efficiency(FE,grains per gram of spike dry weight),the slope between GN and SDW relationship,has been proposed as a possible trait to improve wheat yield potential.The linear relationship between GN and SDW implies a constant increase in GN per unit increase in spike growth and,then a constant FE.However,there are empirical and theoretical elements suggesting that this relationship would not be linear.In this study,we hypothesised and showed that the linearity of the relationship between GN and SDW would be non-linear for extreme values of SDW,implying that the FE would be noticeably reduced at these extreme cases of dry matter allocation to the juvenile spikes.These results have implications for both,genetic and management improvements in grain yield.展开更多
Despite the extensive use of distributed fiber optic sensing(DFOS)in monitoring underground structures,its potential in detecting structural anomalies,such as cracks and cavities,is still not fully understood.To contr...Despite the extensive use of distributed fiber optic sensing(DFOS)in monitoring underground structures,its potential in detecting structural anomalies,such as cracks and cavities,is still not fully understood.To contribute to the identification of defects in underground structures,this study conducted a four-point bending test of a reinforced concrete(RC)beam and uniaxial loading tests of an RC specimen with local cavities.The experimental results revealed the disparity in DFOS strain spike profiles between these two structural anomalies.The effectiveness of DFOS in the quantification of crack opening displacement(COD)was also demonstrated,even in cases where perfect bonding was not achievable between the cable and structures.In addition,DFOS strain spikes observed in two diaphragm wall panels of a twin circular shaft were also reported.The most probable cause of those spikes was identified as the mechanical behavior associated with local concrete contamination.With the utilization of the strain profiles obtained from laboratory tests and field monitoring,three types of multi-classifiers,based on support vector machine(SVM),random forest(RF),and backpropagation neural network(BP),were employed to classify strain profiles,including crack-induced spikes,non-crack-induced spikes,and non-spike strain profiles.Among these classifiers,the SVM-based classifier exhibited superior performance in terms of accuracy and model robustness.This finding suggests that the SVM-based classifier holds promise as a potential solution for the automatic detection and classification of defects in underground structures during long-term monitoring.展开更多
Spike-based neural networks,which use spikes or action potentialsto represent information,have gained a lot of attention because of their high energyefficiency and low power consumption.To fully leverage its advantage...Spike-based neural networks,which use spikes or action potentialsto represent information,have gained a lot of attention because of their high energyefficiency and low power consumption.To fully leverage its advantages,convertingthe external analog signals to spikes is an essential prerequisite.Conventionalapproaches including analog-to-digital converters or ring oscillators,and sensorssuffer from high power and area costs.Recent efforts are devoted to constructingartificial sensory neurons based on emerging devices inspired by the biologicalsensory system.They can simultaneously perform sensing and spike conversion,overcoming the deficiencies of traditional sensory systems.This review summarizesand benchmarks the recent progress of artificial sensory neurons.It starts with thepresentation of various mechanisms of biological signal transduction,followed bythe systematic introduction of the emerging devices employed for artificial sensoryneurons.Furthermore,the implementations with different perceptual capabilitiesare briefly outlined and the key metrics and potential applications are also provided.Finally,we highlight the challenges and perspectives for the future development of artificial sensory neurons.展开更多
The utilization of Inlet Guide Vane (IGV) plays a key factor in affecting the instability evolution. Existing literature mainly focuses on the effect of IGV on instability inception that occurs in the rotor region. Ho...The utilization of Inlet Guide Vane (IGV) plays a key factor in affecting the instability evolution. Existing literature mainly focuses on the effect of IGV on instability inception that occurs in the rotor region. However, with the emergence of compressor instability starting from the stator region, the mechanism of various instability inceptions that occurs in different blade rows due to the change of IGV angles should be further examined. In this study, experiments were focused on three types of instability inceptions observed previously in a 1.5-stage axial flow compressor. To analyze the conversion of stall evolutions, the compressor rotating speed was set to 17 160 r/min, at which both the blade loading in the stator hub region and rotor tip region were close to the critical value before final compressor stall. Meanwhile, the dynamic test points with high-response were placed to monitor the pressures both at the stator trailing edges and rotor tips. The results indicate that the variation of reaction determines the region where initial instability occurs. Indeed, negative pre-rotation of the inlet guide vane leads to high-reaction, initiating stall disturbance from the rotor region. Positive pre-rotation results in low-reaction, initiating stall disturbance from the stator region. Furthermore, the type of instability evolution is affected by the radial loading distribution under different IGV angles. Specifically, a spike-type inception occurs at the rotor blade tip with a large angle of attack at the rotor inlet (−2°, −4° and −6°). Meanwhile, the critical total pressure ratio at the rotor tip is 1.40 near stall. As the angle of attack decreases, the stator blade loading reaches its critical boundary, with a value of approximately 1.35. At this moment, if the rotor tip maintains high blade loading similar to the stator hub, the partial surge occurs (0° and +2°);otherwise, the hub instability occurs (+4° and +6°).展开更多
Rice spike detection and counting play a crucial role in rice yield research.Automatic detection technology based on Unmanned Aerial Vehicle(UAV)imagery has the advantages of flexibility,efficiency,low cost,safety,and...Rice spike detection and counting play a crucial role in rice yield research.Automatic detection technology based on Unmanned Aerial Vehicle(UAV)imagery has the advantages of flexibility,efficiency,low cost,safety,and reliability.However,due to the complex field environment and the small target morphology of some rice spikes,the accuracy of detection and counting is relatively low,and the differences in phenotypic characteristics of rice spikes at different growth stages have a significant impact on detection results.To solve the above problems,this paper improves the You Only Look Once v8(YOLOv8)model,proposes a new method for detecting and counting rice spikes,and designs a comparison experiment using rice spike detection in different periods.Themethod improves the model’s ability to detect rice ears with special morphologies by introducing a Dynamic Snake Convolution(DSConv)module into the Bottleneck of the C2f structure of YOLOv8,which enhances themodule’s ability to extract elongated structural features;In addition,the Weighted Interpolation of Sequential Evidence for Intersection over Union(Wise-IoU)loss function is improved to reduce the harmful gradient of lowquality target frames and enhance themodel’s ability to locate small spikelet targets,thus improving the overall detection performance of the model.The experimental results show that the enhanced rice spike detection model has an average accuracy of 91.4%and a precision of 93.3%,respectively,which are 2.3 percentage points and 2.5 percentage points higher than those of the baseline model.Furthermore,it effectively reduces the occurrence of missed and false detections of rice spikes.In addition,six rice spike detection models were developed by training the proposed models with images of rice spikes at themilk and waxmaturity stages.The experimental findings demonstrated that the models trained on milk maturity data attained the highest detection accuracy for the same data,with an average accuracy of 96.2%,an R squared(R^(2))value of 0.71,and a Rootmean squared error(RMSE)of 20.980.This study provides technical support for early and non-destructive yield estimation in rice in the future.展开更多
Wheat(Triticum aestivum L.)is an important staple food crop in the world and supplies about 20%of human caloric and protein consumption(Giraldo et al.,2019;Xiao et al.,2022).Wheat production accounts for~30%of global ...Wheat(Triticum aestivum L.)is an important staple food crop in the world and supplies about 20%of human caloric and protein consumption(Giraldo et al.,2019;Xiao et al.,2022).Wheat production accounts for~30%of global cereal crops(Li et al.,2019).With the global population increasing and the frequency of natural disasters rising,enhancing wheat yield is crucial to meet food demand.Spike traits such as increased grain number per spike are key determinants of wheat yield.Pre-harvest sprouting(PHS)is a significant natural disaster that severely impacts grain yield and end-use quality of wheat(Tai et al.,2021,2024).展开更多
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘In this paper, a Non-Ablative Thermal Protection System(NATPS) with the spiked body and the opposing jet combined configuration is proposed to reduce the aerodynamic heating of the hypersonic vehicle, and the coupled fluid-thermal numerical analysis is performed to study the thermal control performance of the NATPS. The results show that the spiked body pushes the bow shock away from the protected structure and thus reduces the shock intensity and the wall heat flux. In addition, the low temperature gas of the opposing jet separates the high temperature gas behind the shock from the nose cone of the spiked body, ensuring the non-ablative property of the spiked body. Therefore, the NATPS reduces the aerodynamic heating by the reconfiguration of the flow field, and the thermal control efficiency of the system is better than the Thermal Protection System(TPS) with the single spiked body and the single opposing jet. The influencing factors of the NATPS are analyzed. Both increasing the length of the spiked body and reducing the total temperature of the opposing jet can improve the thermal control performance of the NATPS and the nonablative property of the spiked body. However, increasing the heat conductivity coefficient of the spiked body can enhance benefit the non-ablative property of the spiked body, but has little influence on the thermal control performance of the NATPS.
文摘By adopting the CFD based approach,the hypersonic flow nature is investigated under a Free-stream Mach number of 6 for two distinct re-entry configurations;namely,a spiked conical-nosed body,and a spiked T-shaped blunt-nosed body,each coupled with counterflow jets.A high-fidelity structured mesh and the SST k-omega Turbulence model within the Ansys Fluent framework are employed to capture flow phenomena like bow shock detachment,recirculation,and wake formation with finer precision.The analysis is performed on vital performance parameters such as aerodynamic drag,surface pressure and temperature distributions,and the effect of counterflow jets on shock stand-off distance and thermal load reduction.We find results indicating drag reduction of 52%by the conical blunt-nosed configuration compared to the T-Shape nose configuration and an increase in shock stand-off distance by 0.0175.Moreover,counterflow jets reduce the surface temperature by a maximum of 300 K at critical forebody regions,while the total pressure recovery improves by 50%.These findings affirm that nose shape is a critical parameter influencing the hypersonic flow control and thus offers new perspectives for the design optimization,with T-shaped configuration providing improved thermal protection and aerodynamic efficiency.
基金Funding for this research was provided by the Australia Grain Research and Development Corporation(9176507)the Western Crop Genetics Alliance.Jingye Cheng thanks The University of Tasmania,Australia for the scholarship(495802)。
文摘Improved yield potential is the goal of barley domestication and cultivation.During this process,two-and six-rowed barley types emerged and have been utilised in breeding and production.The six-rowed type could produce three times as many grains as its ancestral two-rowed forms,thus dominating barley cultivation for thousands of years.The deficiens form of the two-rowed type,characterised by extremely suppressed lateral spikelets,has gained dominance over the past few decades in barley-growing regions worldwide.We hypothesised that the absence of lateral spikelets in deficiens barley affects spike architecture and spike-related traits,contributing to its superior yield potential of deficiens barley cultivation.Currently,a deficiens barley variety,RGT Planet,is the most popular barley variety in the world.In this study,we used two F_(2) populations derived from crossing RGT Planet with two canonical two-rowed barley and identified the functional allele Vrs1.t1 associated with deficiens morphology.We observed that the Vrs1.t1 allele may contribute to high yield potential by optimising spike architecture through increased spikelet length,grain number,and grain size.Phylogenetic analysis suggests that the deficiens mutation was likely present from the early stages of barley cultivation in the Fertile Crescent and spread to Ethiopia and beyond with agricultural expansion.We conclude that the ancient deficiens allele Vrs1.t1 has been a critical driver for the recent success of modern barley improvement by optimising spike architecture.
基金supported by the National Natural Science Foundation of China(82173796)the Research Project of Zhejiang Chinese Medical University(2023JKZDZC04).
文摘When teaching neurology students about epilepsy,selecting appropriate antiseizure medications(ASMs)based on seizure type is a fundamental objective.Carbamazepine(CBZ),a widely used first-line ASM,is effective against focal seizures,generalized tonic-clonic seizures,and mixed seizure patterns[1].However,CBZ paradoxically aggravates absence seizures,as demonstrated by increased 36 Hz spike-and-wave discharges(SWDs)in both patients and animal models[2,3].While prior studies implicated altered GABAA receptor function in the thalamic ventrobasal complex[4],the precise mechanisms remained unclear.Recently,an inspiring study published on PNAS by Jang et al.from Stanford University has highlighted the thalamic reticular nucleus(RT)as the key brain region responsible for CBZ's aggravating effect on absence seizures[5].The combination of transgenic mouse models,optogenetics,and detailed electrophysiology in the original study provided exceptional precision in probing mechanistic insights,which greatly strengthens the conclusions.
文摘Background:Beverages play a positive role in a balanced diet.Beverages can provide an enjoyable and refreshing mind to reach a particular target.In beverages,date-rape drugs,such as Rohypnol,gamma-hydroxybutyric acid,and ketamine,were usually added to make victims to become weak,confused,unconscious,and vulnerable.Aims and Objectives:The aims and objectives of the research work are to analyze the beverages,viz.,Sprite,Coca-Cola and Coffee by analytical techniques and to degrade the date-rape drug present in the beverages by photocatalysis using activated carbon as the photocatalyst material.Materials and Methods:The drug(clonazepam)and beverages used in the research work were analyzed using FTIR,UV and HPLC techniques.Results:From the FTIR,in beverages(Sprite and Coca-Cola),the peaks corresponding to C-O and O-H functional groups confirmed the presence of CO_(2)and H_(2)O and in Coffee,the presence ofν_(as)(COC)andνs(COC)vibration bands is found out.The UV-visible analysis confirmed theλ_(max)value for activated carbon as 251 nm.Under visible light and activated carbon photocatalyst,53.57%of drug molecule was degraded from coca cola which was found to be highest than other beverages.The degradation of drug molecule was also confirmed by the reduction in the peak area for a particular retention time through HPLC analysis.Conclusion:Photocatalysis can be effectively used to remove any drug present in the spike drinks.
基金support from the Beijing Natural Science Foundation-Xiaomi Innovation Joint Fund(No.L233009)National Natural Science Foundation of China(NSFC Nos.62422409,62174152,and 62374159)from the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020115).
文摘Memristors have a synapse-like two-terminal structure and electrical properties,which are widely used in the construc-tion of artificial synapses.However,compared to inorganic materials,organic materials are rarely used for artificial spiking synapses due to their relatively poor memrisitve performance.Here,for the first time,we present an organic memristor based on an electropolymerized dopamine-based memristive layer.This polydopamine-based memristor demonstrates the improve-ments in key performance,including a low threshold voltage of 0.3 V,a thin thickness of 16 nm,and a high parasitic capaci-tance of about 1μF·mm^(-2).By leveraging these properties in combination with its stable threshold switching behavior,we con-struct a capacitor-free and low-power artificial spiking neuron capable of outputting the oscillation voltage,whose spiking fre-quency increases with the increase of current stimulation analogous to a biological neuron.The experimental results indicate that our artificial spiking neuron holds potential for applications in neuromorphic computing and systems.
基金supports from National Natural Science Foundation of China(62171087,62475036).
文摘Photonic hardware implementation of spiking neural networks,regarded as a viable potential paradigm for ultra-high speed and energy efficiency computing,leverages spatiotemporal spike encoding and event-driven dynamics to simulate brain-like parallel information processing.Silicon-based microring resonators(MRRs)offer a power efficiency and ultrahigh flexibility scheme to mimic biological neuron,however,their substantial potential for integrated neuromorphic systems remains limited by insufficient exploration of MRR-based spiking digital and analog computation.Here,an all-optical neural dynamics framework,encompassing both excitatory and inhibitory behaviors based on multi-wavelength auxiliary and competition mechanism in an MRR,is proposed numerically.Leveraging multi-wavelength resonance characteristics and wavelength division multiplexing(WDM)technology,a single MRR implements the five fundamental optical digital logic gates:AND,OR,NOT,XNOR and XOR.Besides,the cascading capabilities of MRR-based spiking neurons are demonstrated through multi-level digital logic gates including NAND,NOR,4-input AND,8-input AND,and a full adder,emphasizing their promise for large-scale digital logic networks.Furthermore,an exemplary binary convolution has been achieved by utilizing the proposed MRR-based digital logic operation,illustrating the potential of all-optical binary convolution to compute image gradient magnitudes for edge detection.Such passive photonic neurons and networks promise access to the high transmission speed and low power consumption inherent to optical systems,thus enabling direct hardware-algorithm co-computation and accelerating artificial intelligence.
基金mainly funded by the State Research Agency of Spain through the Competitive Project PID2021-127415OB-I00 on "Spike fertility in wheat" with some contribution from an AGROTECNIO Seed-funding on "Analysing the physiology of spike density to provide support to selection in breeding programs"RAS did part of the work in this project during a research stay at the Crop Physiology Lab of the University of Lleida co-funded by AUIP (Postgraduate Iberoamerican University Association) grants+1 种基金core funds Crop Physiology Lab of the Ud L. CSC held a Maria Zambrano’s fellowship from the University of Lleida funded by the Spanish Ministry of Universities and the European Social Fund and is a member of CONICET (the Scientific Research Council of Argentina)INTA (the National Institute of Agriculture Technology of Argentina)
文摘Grain yield variation has been associated to variation in grain number per unit area(GN).It has been shown in the last about 40 years that GN is linearly associated to the spike dry weight(SDW)at anthesis in wheat,fact that has been useful to understand mechanistically potential grain yield.Fruiting efficiency(FE,grains per gram of spike dry weight),the slope between GN and SDW relationship,has been proposed as a possible trait to improve wheat yield potential.The linear relationship between GN and SDW implies a constant increase in GN per unit increase in spike growth and,then a constant FE.However,there are empirical and theoretical elements suggesting that this relationship would not be linear.In this study,we hypothesised and showed that the linearity of the relationship between GN and SDW would be non-linear for extreme values of SDW,implying that the FE would be noticeably reduced at these extreme cases of dry matter allocation to the juvenile spikes.These results have implications for both,genetic and management improvements in grain yield.
基金support from the Open Research Project Programme of the State Key Laboratory of Internet of Things for Smart City,University of Macao (Grant No.SKL-IoTSC (UM)-2021-2023/ORPF/A19/2022)the General Research Fund project from Research Grants Council of Hong Kong Special Administrative Region Government of China (Grant No.15214722)the Start-up Fund from The Hong Kong Polytechnic University (Grant No.BD88).
文摘Despite the extensive use of distributed fiber optic sensing(DFOS)in monitoring underground structures,its potential in detecting structural anomalies,such as cracks and cavities,is still not fully understood.To contribute to the identification of defects in underground structures,this study conducted a four-point bending test of a reinforced concrete(RC)beam and uniaxial loading tests of an RC specimen with local cavities.The experimental results revealed the disparity in DFOS strain spike profiles between these two structural anomalies.The effectiveness of DFOS in the quantification of crack opening displacement(COD)was also demonstrated,even in cases where perfect bonding was not achievable between the cable and structures.In addition,DFOS strain spikes observed in two diaphragm wall panels of a twin circular shaft were also reported.The most probable cause of those spikes was identified as the mechanical behavior associated with local concrete contamination.With the utilization of the strain profiles obtained from laboratory tests and field monitoring,three types of multi-classifiers,based on support vector machine(SVM),random forest(RF),and backpropagation neural network(BP),were employed to classify strain profiles,including crack-induced spikes,non-crack-induced spikes,and non-spike strain profiles.Among these classifiers,the SVM-based classifier exhibited superior performance in terms of accuracy and model robustness.This finding suggests that the SVM-based classifier holds promise as a potential solution for the automatic detection and classification of defects in underground structures during long-term monitoring.
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grants No.2021B0909060002)National Natural Science Foundation of China(Grants No.62204219,62204140)Major Program of Natural Science Foundation of Zhejiang Province(Grants No.LDT23F0401).
文摘Spike-based neural networks,which use spikes or action potentialsto represent information,have gained a lot of attention because of their high energyefficiency and low power consumption.To fully leverage its advantages,convertingthe external analog signals to spikes is an essential prerequisite.Conventionalapproaches including analog-to-digital converters or ring oscillators,and sensorssuffer from high power and area costs.Recent efforts are devoted to constructingartificial sensory neurons based on emerging devices inspired by the biologicalsensory system.They can simultaneously perform sensing and spike conversion,overcoming the deficiencies of traditional sensory systems.This review summarizesand benchmarks the recent progress of artificial sensory neurons.It starts with thepresentation of various mechanisms of biological signal transduction,followed bythe systematic introduction of the emerging devices employed for artificial sensoryneurons.Furthermore,the implementations with different perceptual capabilitiesare briefly outlined and the key metrics and potential applications are also provided.Finally,we highlight the challenges and perspectives for the future development of artificial sensory neurons.
基金support of the National Natural Science Foundation of China(No.52322603)the Science Center for Gas Turbine Project of China(Nos.P2022-B-II-004-001 and P2023-B-II-001-001)+1 种基金the Fundamental Research Funds for the Central Universities,Chinathe Beijing Nova Program of China(Nos.20220484074 and 20230484479).
文摘The utilization of Inlet Guide Vane (IGV) plays a key factor in affecting the instability evolution. Existing literature mainly focuses on the effect of IGV on instability inception that occurs in the rotor region. However, with the emergence of compressor instability starting from the stator region, the mechanism of various instability inceptions that occurs in different blade rows due to the change of IGV angles should be further examined. In this study, experiments were focused on three types of instability inceptions observed previously in a 1.5-stage axial flow compressor. To analyze the conversion of stall evolutions, the compressor rotating speed was set to 17 160 r/min, at which both the blade loading in the stator hub region and rotor tip region were close to the critical value before final compressor stall. Meanwhile, the dynamic test points with high-response were placed to monitor the pressures both at the stator trailing edges and rotor tips. The results indicate that the variation of reaction determines the region where initial instability occurs. Indeed, negative pre-rotation of the inlet guide vane leads to high-reaction, initiating stall disturbance from the rotor region. Positive pre-rotation results in low-reaction, initiating stall disturbance from the stator region. Furthermore, the type of instability evolution is affected by the radial loading distribution under different IGV angles. Specifically, a spike-type inception occurs at the rotor blade tip with a large angle of attack at the rotor inlet (−2°, −4° and −6°). Meanwhile, the critical total pressure ratio at the rotor tip is 1.40 near stall. As the angle of attack decreases, the stator blade loading reaches its critical boundary, with a value of approximately 1.35. At this moment, if the rotor tip maintains high blade loading similar to the stator hub, the partial surge occurs (0° and +2°);otherwise, the hub instability occurs (+4° and +6°).
基金funded by Jilin Province Innovation and Entrepreneurship Talent Project,grant number 2023QN15funded by Science and Technology Development Plan Project of Jilin Province,grant number 20220202035NC.
文摘Rice spike detection and counting play a crucial role in rice yield research.Automatic detection technology based on Unmanned Aerial Vehicle(UAV)imagery has the advantages of flexibility,efficiency,low cost,safety,and reliability.However,due to the complex field environment and the small target morphology of some rice spikes,the accuracy of detection and counting is relatively low,and the differences in phenotypic characteristics of rice spikes at different growth stages have a significant impact on detection results.To solve the above problems,this paper improves the You Only Look Once v8(YOLOv8)model,proposes a new method for detecting and counting rice spikes,and designs a comparison experiment using rice spike detection in different periods.Themethod improves the model’s ability to detect rice ears with special morphologies by introducing a Dynamic Snake Convolution(DSConv)module into the Bottleneck of the C2f structure of YOLOv8,which enhances themodule’s ability to extract elongated structural features;In addition,the Weighted Interpolation of Sequential Evidence for Intersection over Union(Wise-IoU)loss function is improved to reduce the harmful gradient of lowquality target frames and enhance themodel’s ability to locate small spikelet targets,thus improving the overall detection performance of the model.The experimental results show that the enhanced rice spike detection model has an average accuracy of 91.4%and a precision of 93.3%,respectively,which are 2.3 percentage points and 2.5 percentage points higher than those of the baseline model.Furthermore,it effectively reduces the occurrence of missed and false detections of rice spikes.In addition,six rice spike detection models were developed by training the proposed models with images of rice spikes at themilk and waxmaturity stages.The experimental findings demonstrated that the models trained on milk maturity data attained the highest detection accuracy for the same data,with an average accuracy of 96.2%,an R squared(R^(2))value of 0.71,and a Rootmean squared error(RMSE)of 20.980.This study provides technical support for early and non-destructive yield estimation in rice in the future.
基金supported by the National Key Research and Development Program of China(2023YFD1200403 and 2023YFF1000600)the Innovation Program of Chinese Academy of Agricultural Sciences。
文摘Wheat(Triticum aestivum L.)is an important staple food crop in the world and supplies about 20%of human caloric and protein consumption(Giraldo et al.,2019;Xiao et al.,2022).Wheat production accounts for~30%of global cereal crops(Li et al.,2019).With the global population increasing and the frequency of natural disasters rising,enhancing wheat yield is crucial to meet food demand.Spike traits such as increased grain number per spike are key determinants of wheat yield.Pre-harvest sprouting(PHS)is a significant natural disaster that severely impacts grain yield and end-use quality of wheat(Tai et al.,2021,2024).
