In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes ...In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes in population density.In this paper,we consider a reaction-diffusion-advection model with nonlocal delay and Dirichlet boundary conditions.First of all,we investigate the well-posedness of solution of model.Then,the existence of positive steady state is proofed by implicit function theorem.Based on a priori estimate for the eigenvalue,we prove the stability of the positive steady state and conclude the associated distribution of Hopf bifurcation.Our research indicates that the combined effects of nonlocal and time delays have a certain impact on the dynamics of the model.展开更多
Delay Alignment Modulation(DAM)is an innovative broadband modulation technique well-suited for millimeter Wave(mm Wave)and Terahertz(THz)massive Multiple-Input Multiple-Output(MIMO)communication systems.Leveraging the...Delay Alignment Modulation(DAM)is an innovative broadband modulation technique well-suited for millimeter Wave(mm Wave)and Terahertz(THz)massive Multiple-Input Multiple-Output(MIMO)communication systems.Leveraging the high spatial resolution and sparsity of multi-path channels,DAM effectively mitigates Inter-Symbol Interference(ISI)by aligning all multi-path components through a combination of delay pre-compensation(or post-compensation)and path-based beamforming.As such,ISI is eliminated while preserving multi-path power gains.In this paper,we investigate multi-user double-side DAM,which incorporates both delay pre-compensation at the transmitter and post-compensation at the receiver,in contrast to prior works that primarily focus on singleside DAM with only delay pre-compensation.Firstly,we derive the constraint on the number of introduced delays and formulate the corresponding delay pre/post-compensation vectors tailored for multi-user double-side DAM,given a specific number of delay compensations.Furthermore,we demonstrate that when the number of Base Stations(BSs)/User Equipment(UE)antennas is sufficiently large,single-side DAM—where delay compensation is performed only at the BS/UE—is preferable to double-side DAM,since the former results in less ISI to be spatially eliminated.Next,we propose two low-complexity path-based beamforming strategies based on the eigen-beamforming transmission and ISI-Zero Forcing(ZF),respectively.On this basis,we further analyze the achievable sum rates.Simulation results verify that with a sufficiently large number of BS/UE antennas,singleside DAM is adequate for ISI elimination.Moreover,compared to the benchmarking scheme of Orthogonal Frequency Division Multiplexing(OFDM),multi-user BS-side DAM achieves higher spectral efficiency and lower Peak-to-Average Power Ratio(PAPR).展开更多
The flight envelope of Air Turbo Rocket(ATR)engines is broader compared to conventional aero-engines,and designing a full-envelope controller using traditional methods poses significant challenges due to a burdensome ...The flight envelope of Air Turbo Rocket(ATR)engines is broader compared to conventional aero-engines,and designing a full-envelope controller using traditional methods poses significant challenges due to a burdensome design process.To address this issue,this paper proposes a self-learning neural network controller design method based on Reinforcement Learning(RL).Additionally,a method for predictive compensation and stability rewards is proposed to reduce the system oscillation caused by actuator delay.This approach simplifies the actuator to a firstorder inertial element exhibiting pure delay.A simulation environment for the ATR engineactuator system is first established.Based on this environment,a self-learning neural network controller using a predictive compensator and the Proximal Policy Optimization(PPO)algorithm is then developed.Furthermore,the temporal difference signals from the controller output are integrated into the reward function to enhance system stability.The proposed method is validated through numerical simulations and semi-physical experiments.The numerical simulation results demonstrate that the proposed method increases the system's tolerance to delays from 20 ms to 400 ms.Under an actuator delay of 400 ms,the average steady-state error remains less than0.1%,the overshoot is limited to 1%,and the settling time does not exceed 3 s.Moreover,compared to the traditional method,the proposed method exhibits higher adaptability to model errors and variations in flight conditions.In the conducted semi-physical simulation experiments,the proposed method achieves stable control of a real electric pump.展开更多
The development of polymeric materials that exhibit blue thermally activated delayed fluorescence(TADF)is of great interest for optoelectronic applications.However,achieving TADF in polymers often requires an elaborat...The development of polymeric materials that exhibit blue thermally activated delayed fluorescence(TADF)is of great interest for optoelectronic applications.However,achieving TADF in polymers often requires an elaborate monomer design.The high-energy local triplet state(^(3)LE)of carbazole complicates its application despite the molecular orbital arrangement being suitable for blue emission.Here,we present an approach to polymer design that makes it possible to solve this problem.We demonstrate the in situ formation of a TADF donor-acceptor system during Suzuki polycondensation,creating an extended carbazole-based donor matrix coupled with a triazine acceptor.The resulting polymer exhibited efficient TADF with a low energy gap(ΔE_(ST))value if a phenyl N-substituent,enabling essential electron delocalization,was present in the carbazole moiety.This work establishes a versatile platform for developing carbazole-based TADF polymers,overcoming the fundamental limitations that hinder their widespread application.展开更多
Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the ...Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the authors present a machine learning-based risk prediction approach using routinely available clinical and laboratory parameters.Among the evaluated algorithms,a decision tree model demonstrated excellent discrimination,achieving an area under the curve of 0.951 in the validation set and notably identifying all true cases of delayed wound healing at the Youden index threshold.The inclusion of variables such as drainage duration,preoperative white blood cell and neutrophil counts,alongside age and sex,highlights the pragmatic appeal of the model for early postoperative monitoring.Nevertheless,several aspects warrant critical reflection,including the reliance on a postoperative variable(drainage duration),internal validation only,and certain reporting inconsistencies.This letter underscores both the promise and the limitations of adopting interpretable machine learning models in perioperative care.We advocate for transparent reporting,external validation,and careful consideration of clinically actionable timepoints before integration into practice.Ultimately,this work represents a valuable step toward precision risk stratification in gastric cancer surgery,and sets the stage for multicenter,prospective evaluations.展开更多
Time-delayed blasting is widely utilized in engineering to mitigate induced vibration hazards and enhance fragmentation.The underlying vibration reduction principle is the decrease of the charge weight per delay,while...Time-delayed blasting is widely utilized in engineering to mitigate induced vibration hazards and enhance fragmentation.The underlying vibration reduction principle is the decrease of the charge weight per delay,while the potential for further vibration reduction remains debated,largely due to unclear underlying mechanisms.In light of the popularization of electronic detonators and the representativeness of double-hole configurationsfor multiple blastholes,it is essential to investigate the vibration characteristics induced by time-delayed double blastholes.Therefore,a series of doubleborehole experimental blasts was conducted in an underground roadway to clarify the variation in vibration from single-hole to dual-hole conditions.Based on the experimental data and inherent limitations,an exact full-fieldtheoretical model was further employed to systematically analyze the effects of delay time,charge length,and borehole inclination angle on vibrations induced by various doublehole configurations.The experimental data and theoretical analysis reveal that the general scaled distance effectively predicts vibrations in delayed blasting but does not reflectvibration reduction.Increasing delay time causes fluctuatingPPVs,which stabilize slightly above single-hole PPVs as delay times exceed a certain value.The delayed blasting primarily reduces near-fieldfrequencies.Longer charge lengths in double boreholes increase PPV levels and attenuation rates within a certain length,and the vibration behavior of combined long and short charge lengths is governed by the long blasthole.Larger blasthole inclination angles enhance vibration amplitude and reduce PPV attenuation rates.Optimizing inclination angles is more critical than adjusting delay times,and parallel boreholes offer the best vibration control.展开更多
A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescenc...A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescence(TADF)properties.All calculations were performed using density functional theory(DFT)and time‑dependent density functional theory(TDDFT).Calculations for electronic structures,frontier molecular orbital characteristics(which determine the efficiency roll‑off effect of the complexes),and photophysical properties were conducted using the Gaussian 09 software package.The calculation of spin‑orbit coupling matrix elements<T|HSOC|S>,which determine the TADF properties of the complexes,was performed using the ORCA software package.The calculation results show that the auxiliary ligand tetraphenylimidodiphosphinate(tpip),a strong electron‑withdrawing group,can mitigate the efficiency roll‑off effect of the complex.Furthermore,TADF is observed in one of the designed complexes,(F_(3)Phppy)_(2)Ir(tpip),where F_(3)Phppy=2‑[4‑(2,4,6‑trifluorophenyl)phenyl]pyridine.展开更多
Tropospheric zenith wet delay(ZWD)plays a vital role in the analysis of space geodetic observations.In recent years,machine learning methods have been increasingly applied to improve the accuracy of ZWD calculations.H...Tropospheric zenith wet delay(ZWD)plays a vital role in the analysis of space geodetic observations.In recent years,machine learning methods have been increasingly applied to improve the accuracy of ZWD calculations.However,a single machine learning model has limited generalization capabilities.To address these limitations,this study introduces a novel machine learning fusion(MLF)algorithm with stronger generalization capabilities to enhance ZWD modeling and prediction accuracy.The MLF algorithm utilizes a two-layer structure integrating extra trees(ET),backpropagation neural network(BPNN),and linear regression models.By comparing the root mean square error(RMSE)of these models,we found that both ET-based and MLF-based models outperform RF-based and BPNN-based models in terms of internal and external accuracy,across both surface meteorological data-based and blind models.The improvement in exte rnal accuracy is particularly significant in the blind models.Our re sults show that the MLF(with an RMSE of 3.93 cm)and ET(3.99 cm)models outperform the traditional GPT3model(4.07 cm),while the RF(4.21 cm)and BPNN(4.14 cm)have worse external accuracies than the GPT3 model.It is worth noting that the BPNN suffered from overfitting during external accuracy tests,which was avoided by the MLF.In summary,regardless of the availability of surface meteorological data,the MLF-based empirical models demonstrate superior internal and external accuracy compared to the other tested models in this study.展开更多
The increasing demand for flexible displays and wearable electronics has driven extensive efforts to develop stretchable organic lightemitting diodes(OLEDs).A critical challenge in this field is the creation of emissi...The increasing demand for flexible displays and wearable electronics has driven extensive efforts to develop stretchable organic lightemitting diodes(OLEDs).A critical challenge in this field is the creation of emissive layers that combine high efficiency with mechanical robustness.Thermally activated delayed fluorescence(TADF)materials have attracted significant attention as third-generation emitters capable of achieving 100%internal quantum efficiency;however,their application in stretchable OLEDs has been limited.In this study,we propose an elastomer doping strategy.Polyurethane(PU)is incorporated into TADF polymers to improve their mechanical flexibility while maintaining a high luminescent efficiency.The resulting composite films exhibited excellent TADF characteristics and remarkable stretchability(75%).OLEDs fabricated from these materials achieved a maximum external quantum efficiency(EQE)of 14.26%and a peak luminance of 73570 cd·m^(-2),with the PUdoped devices showing a significantly suppressed efficiency roll-off.Additionally,a fully stretchable OLED architecture was designed and operated under tensile strain to maintain stable electroluminescent performance.These results demonstrate that elastomer doping is an effective strategy for balancing the mechanical compliance with optoelectronic performance,offering a promising pathway for the development of high-performance stretchable OLEDs for flexible electronics.展开更多
Delayed neurocognitive recovery following anesthesia and surgery is a common complication in older adult patients.Synapses are fundamental to cognitive function.The activity of synapses heavily depends on the energy s...Delayed neurocognitive recovery following anesthesia and surgery is a common complication in older adult patients.Synapses are fundamental to cognitive function.The activity of synapses heavily depends on the energy supplied by synaptic mitochondria,which are significantly influenced by oxidative stress.Sirtuin 3 is a histone deacetylase located in the mitochondrial matrix that plays a pivotal role in regulating mitochondrial function.However,it remains unclear whether and how sirtuin 3 is involved in the development of delayed cognitive recovery.Therefore,in this study,we investigated the potential role of sirtuin 3 in synapses during delayed neurocognitive recovery.Our results showed that anesthesia and surgery induced cognitive impairment in mice and reduced sirtuin 3 protein expression.Overexpression of sirtuin 3 inhibited opening of the mitochondrial permeability transition pore by reducing acetylation of K166 on cyclophilin D and also rescued cognitive impairment.Aged mice carrying the cyclophilin D-K166R mutation exhibited significantly reduced cognitive impairment.Similarly,administering the mitochondrial permeability transition pore blocker,cyclosporine A,effectively alleviated the decline in synaptic mitochondrial function and cognitive impairment caused by anesthesia and surgery in aged mice.These results indicate that the sirtuin 3/cyclophilin D-K166/mPTP signaling pathway in hippocampal synaptic mitochondria is involved in delayed neurocognitive recovery of aged mice,suggesting this pathway could serve as a potential target for treatment.展开更多
Time delay and Doppler shift between the echo signal and the reference signal are two most commonly used measurements in target localization for the passive radar. Doppler rate, which can be obtained from the extended...Time delay and Doppler shift between the echo signal and the reference signal are two most commonly used measurements in target localization for the passive radar. Doppler rate, which can be obtained from the extended cross ambiguity function, offers an opportunity to further enhance the localization accuracy. This paper considers using the measurement Doppler rate in addition to measurements of time delay and Doppler shift to locate a moving target. A closed-form solution is developed to accurately and efficiently estimate the target position and velocity.The proposed solution establishes a pseudolinear set of equations by introducing some additional variables, imposes weighted least squares formulation to yield a rough estimate, and utilizes the function relation among the target location parameters and additional variables to improve the estimation accuracy. Theoretical covariance and Cramer-Rao lower bound(CRLB) are derived and compared, analytically indicating that the proposed solution attains the CRLB. Numerical simulations corroborate this analysis and demonstrate that the proposed solution outperforms existing methods.展开更多
The proposed Doppler measurement technique shows that the Doppler measurements can be accomplished by a single pulse with multiple frequency components through optical fibre delay lines.Range and velocity ambiguity ca...The proposed Doppler measurement technique shows that the Doppler measurements can be accomplished by a single pulse with multiple frequency components through optical fibre delay lines.Range and velocity ambiguity can be removed,and the velocity resolution can be improved dramatically by using long optical fibre delay lines.Furthermore,the velocity resolution can be modified by adjusting the length of optical fibre delay lines.In addition,the proposed radar can achieve high range resolution by using a single wideband pulse.As a result,the new approach can improve radar performance significantly.展开更多
As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding...As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.展开更多
Deep neural networks(DNNs)are effective in solving both forward and inverse problems for nonlinear partial differential equations(PDEs).However,conventional DNNs are not effective in handling problems such as delay di...Deep neural networks(DNNs)are effective in solving both forward and inverse problems for nonlinear partial differential equations(PDEs).However,conventional DNNs are not effective in handling problems such as delay differential equations(DDEs)and delay integrodifferential equations(DIDEs)with constant delays,primarily due to their low regularity at delayinduced breaking points.In this paper,a DNN method that combines multi-task learning(MTL)which is proposed to solve both the forward and inverse problems of DIDEs.The core idea of this approach is to divide the original equation into multiple tasks based on the delay,using auxiliary outputs to represent the integral terms,followed by the use of MTL to seamlessly incorporate the properties at the breaking points into the loss function.Furthermore,given the increased training dificulty associated with multiple tasks and outputs,we employ a sequential training scheme to reduce training complexity and provide reference solutions for subsequent tasks.This approach significantly enhances the approximation accuracy of solving DIDEs with DNNs,as demonstrated by comparisons with traditional DNN methods.We validate the effectiveness of this method through several numerical experiments,test various parameter sharing structures in MTL and compare the testing results of these structures.Finally,this method is implemented to solve the inverse problem of nonlinear DIDE and the results show that the unknown parameters of DIDE can be discovered with sparse or noisy data.展开更多
Objective:The neurotoxicity of carbon monoxide(CO)to the central nervous system is a key pathogenesis of delayed encephalopathy after acute carbon monoxide poisoning(DEACMP).Our previous study found that retinoic acid...Objective:The neurotoxicity of carbon monoxide(CO)to the central nervous system is a key pathogenesis of delayed encephalopathy after acute carbon monoxide poisoning(DEACMP).Our previous study found that retinoic acid(RA)can suppress the neurotoxic effects of CO.This study further explores,in vivo and in vitro,the molecular mechanisms by which RA alleviates CO-induced central nervous system damage.Methods:A cytotoxic model was established using the mouse hippocampal neuronal cell line HT22 and primary oligodendrocytes exposed to CO,and a DEACMP animal model was established in adult Kunming mice.Cell viability and apoptosis of hippocampal neurons and oligodendrocytes were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay and Annexin V/propidium iodide(PI)double staining.The transcriptional and protein expression of each gene was detected using real time fluorescence quantitative PCR(RT-qPCR)and Western blotting.Long noncoding RNA(lncRNA)SNHG15 and LINGO-1 were knocked down or overexpressed to observe changes in neurons and oligodendrocytes.In DEACMP mice,SNHG15 or LINGO-1 were knocked down to assess changes in central nervous tissue and downstream protein expression.Results:RA at 10 and 20μmol/L significantly reversed CO-induced apoptosis of hippocampal neurons and oligodendrocytes,downregulation of SNHG15 and LINGO-1,and upregulation of brain-derived neurotrophic factor(BDNF)and tyrosine kinase receptor B(TrkB)(all P<0.05).Overexpression of SNHG15 or LINGO-1 weakened the protective effect of RA against CO-induced cytotoxicity(all P<0.05).Knockdown of SNHG15 or LINGO-1 alleviated CO-induced apoptosis of hippocampal neurons and oligodendrocytes and upregulated BDNF and TrkB expression levels(all P<0.05).Experiments in DEACMP model mice showed that knockdown of SNHG15 or LINGO-1 mitigated central nervous system injury in DEACMP(all P<0.05).Conclusion:RA alleviates CO-induced apoptosis of hippocampal neurons and oligodendrocytes,thereby reducing central nervous system injury and exerting neuroprotective effects.LncRNA SNHG15 and LINGO-1 are key molecules mediating RA induced inhibition of neuronal apoptosis and are associated with the BDNF/TrkB pathway.These findings provide a theoretical framework for optimizing the clinical treatment of DEACMP and lay an experimental foundation for elucidating its molecular mechanisms.展开更多
Wireless communication-enabled Cooperative Adaptive Cruise Control(CACC)is expected to improve the safety and traffic capacity of vehicle platoons.Existing CACC considers a conventional communication delay with fixed ...Wireless communication-enabled Cooperative Adaptive Cruise Control(CACC)is expected to improve the safety and traffic capacity of vehicle platoons.Existing CACC considers a conventional communication delay with fixed Vehicular Communication Network(VCN)topologies.However,when the network is under attack,the communication delay may be much higher,and the stability of the system may not be guaranteed.This paper proposes a novel communication Delay Aware CACC with Dynamic Network Topologies(DADNT).The main idea is that for various communication delays,in order to maximize the traffic capacity while guaranteeing stability and minimizing the following error,the CACC should dynamically adjust the VCN network topology to achieve the minimum inter-vehicle spacing.To this end,a multi-objective optimization problem is formulated,and a 3-step Divide-And-Conquer sub-optimal solution(3DAC)is proposed.Simulation results show that with 3DAC,the proposed DADNT with CACC can reduce the inter-vehicle spacing by 5%,10%,and 14%,respectively,compared with the traditional CACC with fixed one-vehicle,two-vehicle,and three-vehicle look-ahead network topologies,thereby improving the traffic efficiency.展开更多
The integrated optical true time delay phased array antenna system has the advantages of high bandwidth,small size,low loss and strong antiinterference capability,etc.The high integration of the optically controlled p...The integrated optical true time delay phased array antenna system has the advantages of high bandwidth,small size,low loss and strong antiinterference capability,etc.The high integration of the optically controlled phased array antenna system is a necessary trend for the future development of the phased array,and it is also a major focus and difficulty in the current research of integrated microwave photonics.This paper firstly introduces the basic principle and development history of optical true time delay phased array antenna system based on microwave photonics,and briefly introduces the main implementation methods and integration platform of optical true time delay.Then,the application and development prospect of optical true time delay technology in beam control of phased array antenna system are mainly presented.Finally,according to the current research progress,the possible research directions of integrated optically controlled phased array antenna systems in the future are proposed.展开更多
To address the issue of low measurement accuracy caused by noise interference in the acquisition of low fluid flow rate signals with ultrasonic Doppler flow meters,a novel signal processing algorithm that combines ens...To address the issue of low measurement accuracy caused by noise interference in the acquisition of low fluid flow rate signals with ultrasonic Doppler flow meters,a novel signal processing algorithm that combines ensemble empirical mode decomposition(EEMD)and cross-correlation algorithm was proposed.Firstly,a fast Fourier transform(FFT)spectrum analysis was utilized to ascertain the frequency range of the signal.Secondly,data acquisition was conducted at an appropriate sampling frequency,and the acquired Doppler flow rate signal was then decomposed into a series of intrinsic mode functions(IMFs)by EEMD.Subsequently,these decomposed IMFs were recombined based on their energy entropy,and then the noise of the recombined Doppler flow rate signal was removed by cross-correlation filtering.Finally,an ideal ultrasonic Doppler flow rate signal was extracted.Simulation and experimental verification show that the proposed Doppler flow signal processing method can effectively enhance the signal-to-noise ratio(SNR)and extend the lower limit of measurement of the ultrasonic Doppler flow meter.展开更多
In this paper,we investigate the periodic traveling wave solutions problem for a single population model with advection and distributed delay.By the bifurcation analysis method,we can obtain periodic traveling wave so...In this paper,we investigate the periodic traveling wave solutions problem for a single population model with advection and distributed delay.By the bifurcation analysis method,we can obtain periodic traveling wave solutions for this model under the influence of advection term and distributed delay.The obtained results indicate that weak kernel and strong kernel can both deduce the existence of periodic traveling wave solutions.Finally,we apply the main results in this paper to Logistic model and Nicholson’s blowflies model.展开更多
基金Supported by the Natural Science Foundation of Shanghai(23ZR1401700)National Natural Science Foundation of China(12471157)。
文摘In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes in population density.In this paper,we consider a reaction-diffusion-advection model with nonlocal delay and Dirichlet boundary conditions.First of all,we investigate the well-posedness of solution of model.Then,the existence of positive steady state is proofed by implicit function theorem.Based on a priori estimate for the eigenvalue,we prove the stability of the positive steady state and conclude the associated distribution of Hopf bifurcation.Our research indicates that the combined effects of nonlocal and time delays have a certain impact on the dynamics of the model.
基金supported in part by the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province under Grant BK20240070in part by the National Natural Science Foundation of China under Grant 62071114n part by the Fundamental Research Funds for the Central Universities under Grant 2242022k60004。
文摘Delay Alignment Modulation(DAM)is an innovative broadband modulation technique well-suited for millimeter Wave(mm Wave)and Terahertz(THz)massive Multiple-Input Multiple-Output(MIMO)communication systems.Leveraging the high spatial resolution and sparsity of multi-path channels,DAM effectively mitigates Inter-Symbol Interference(ISI)by aligning all multi-path components through a combination of delay pre-compensation(or post-compensation)and path-based beamforming.As such,ISI is eliminated while preserving multi-path power gains.In this paper,we investigate multi-user double-side DAM,which incorporates both delay pre-compensation at the transmitter and post-compensation at the receiver,in contrast to prior works that primarily focus on singleside DAM with only delay pre-compensation.Firstly,we derive the constraint on the number of introduced delays and formulate the corresponding delay pre/post-compensation vectors tailored for multi-user double-side DAM,given a specific number of delay compensations.Furthermore,we demonstrate that when the number of Base Stations(BSs)/User Equipment(UE)antennas is sufficiently large,single-side DAM—where delay compensation is performed only at the BS/UE—is preferable to double-side DAM,since the former results in less ISI to be spatially eliminated.Next,we propose two low-complexity path-based beamforming strategies based on the eigen-beamforming transmission and ISI-Zero Forcing(ZF),respectively.On this basis,we further analyze the achievable sum rates.Simulation results verify that with a sufficiently large number of BS/UE antennas,singleside DAM is adequate for ISI elimination.Moreover,compared to the benchmarking scheme of Orthogonal Frequency Division Multiplexing(OFDM),multi-user BS-side DAM achieves higher spectral efficiency and lower Peak-to-Average Power Ratio(PAPR).
基金co-supported by the National Science and Technology Major Project(No.J2019-Ⅲ-0010-0054)the National Natural Science Foundation of China(No.52336002)。
文摘The flight envelope of Air Turbo Rocket(ATR)engines is broader compared to conventional aero-engines,and designing a full-envelope controller using traditional methods poses significant challenges due to a burdensome design process.To address this issue,this paper proposes a self-learning neural network controller design method based on Reinforcement Learning(RL).Additionally,a method for predictive compensation and stability rewards is proposed to reduce the system oscillation caused by actuator delay.This approach simplifies the actuator to a firstorder inertial element exhibiting pure delay.A simulation environment for the ATR engineactuator system is first established.Based on this environment,a self-learning neural network controller using a predictive compensator and the Proximal Policy Optimization(PPO)algorithm is then developed.Furthermore,the temporal difference signals from the controller output are integrated into the reward function to enhance system stability.The proposed method is validated through numerical simulations and semi-physical experiments.The numerical simulation results demonstrate that the proposed method increases the system's tolerance to delays from 20 ms to 400 ms.Under an actuator delay of 400 ms,the average steady-state error remains less than0.1%,the overshoot is limited to 1%,and the settling time does not exceed 3 s.Moreover,compared to the traditional method,the proposed method exhibits higher adaptability to model errors and variations in flight conditions.In the conducted semi-physical simulation experiments,the proposed method achieves stable control of a real electric pump.
基金supported by the Russian Science Foundation (No. 25-13-00300)the Centre for Optical and Laser Materials Research (SPbSU) and Saint Petersburg State University for measuring the quantum yields of luminescence within the framework of research project(No.125021902439-8)。
文摘The development of polymeric materials that exhibit blue thermally activated delayed fluorescence(TADF)is of great interest for optoelectronic applications.However,achieving TADF in polymers often requires an elaborate monomer design.The high-energy local triplet state(^(3)LE)of carbazole complicates its application despite the molecular orbital arrangement being suitable for blue emission.Here,we present an approach to polymer design that makes it possible to solve this problem.We demonstrate the in situ formation of a TADF donor-acceptor system during Suzuki polycondensation,creating an extended carbazole-based donor matrix coupled with a triazine acceptor.The resulting polymer exhibited efficient TADF with a low energy gap(ΔE_(ST))value if a phenyl N-substituent,enabling essential electron delocalization,was present in the carbazole moiety.This work establishes a versatile platform for developing carbazole-based TADF polymers,overcoming the fundamental limitations that hinder their widespread application.
文摘Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the authors present a machine learning-based risk prediction approach using routinely available clinical and laboratory parameters.Among the evaluated algorithms,a decision tree model demonstrated excellent discrimination,achieving an area under the curve of 0.951 in the validation set and notably identifying all true cases of delayed wound healing at the Youden index threshold.The inclusion of variables such as drainage duration,preoperative white blood cell and neutrophil counts,alongside age and sex,highlights the pragmatic appeal of the model for early postoperative monitoring.Nevertheless,several aspects warrant critical reflection,including the reliance on a postoperative variable(drainage duration),internal validation only,and certain reporting inconsistencies.This letter underscores both the promise and the limitations of adopting interpretable machine learning models in perioperative care.We advocate for transparent reporting,external validation,and careful consideration of clinically actionable timepoints before integration into practice.Ultimately,this work represents a valuable step toward precision risk stratification in gastric cancer surgery,and sets the stage for multicenter,prospective evaluations.
基金supported by the National Natural Science Foundation of China(Grant Nos.42407267 and 52374152)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20220975).
文摘Time-delayed blasting is widely utilized in engineering to mitigate induced vibration hazards and enhance fragmentation.The underlying vibration reduction principle is the decrease of the charge weight per delay,while the potential for further vibration reduction remains debated,largely due to unclear underlying mechanisms.In light of the popularization of electronic detonators and the representativeness of double-hole configurationsfor multiple blastholes,it is essential to investigate the vibration characteristics induced by time-delayed double blastholes.Therefore,a series of doubleborehole experimental blasts was conducted in an underground roadway to clarify the variation in vibration from single-hole to dual-hole conditions.Based on the experimental data and inherent limitations,an exact full-fieldtheoretical model was further employed to systematically analyze the effects of delay time,charge length,and borehole inclination angle on vibrations induced by various doublehole configurations.The experimental data and theoretical analysis reveal that the general scaled distance effectively predicts vibrations in delayed blasting but does not reflectvibration reduction.Increasing delay time causes fluctuatingPPVs,which stabilize slightly above single-hole PPVs as delay times exceed a certain value.The delayed blasting primarily reduces near-fieldfrequencies.Longer charge lengths in double boreholes increase PPV levels and attenuation rates within a certain length,and the vibration behavior of combined long and short charge lengths is governed by the long blasthole.Larger blasthole inclination angles enhance vibration amplitude and reduce PPV attenuation rates.Optimizing inclination angles is more critical than adjusting delay times,and parallel boreholes offer the best vibration control.
文摘A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescence(TADF)properties.All calculations were performed using density functional theory(DFT)and time‑dependent density functional theory(TDDFT).Calculations for electronic structures,frontier molecular orbital characteristics(which determine the efficiency roll‑off effect of the complexes),and photophysical properties were conducted using the Gaussian 09 software package.The calculation of spin‑orbit coupling matrix elements<T|HSOC|S>,which determine the TADF properties of the complexes,was performed using the ORCA software package.The calculation results show that the auxiliary ligand tetraphenylimidodiphosphinate(tpip),a strong electron‑withdrawing group,can mitigate the efficiency roll‑off effect of the complex.Furthermore,TADF is observed in one of the designed complexes,(F_(3)Phppy)_(2)Ir(tpip),where F_(3)Phppy=2‑[4‑(2,4,6‑trifluorophenyl)phenyl]pyridine.
基金funded by National Natural Science Foundation of China Key Program(12431014)Key Project of Hunan Education Department(22A0126)+1 种基金Natural Science Foundation of Hunan Province(2022JJ30555)Postgraduate Scientific Research Innovation Project of Xiangtan University(XDCX2024Y172)。
文摘Tropospheric zenith wet delay(ZWD)plays a vital role in the analysis of space geodetic observations.In recent years,machine learning methods have been increasingly applied to improve the accuracy of ZWD calculations.However,a single machine learning model has limited generalization capabilities.To address these limitations,this study introduces a novel machine learning fusion(MLF)algorithm with stronger generalization capabilities to enhance ZWD modeling and prediction accuracy.The MLF algorithm utilizes a two-layer structure integrating extra trees(ET),backpropagation neural network(BPNN),and linear regression models.By comparing the root mean square error(RMSE)of these models,we found that both ET-based and MLF-based models outperform RF-based and BPNN-based models in terms of internal and external accuracy,across both surface meteorological data-based and blind models.The improvement in exte rnal accuracy is particularly significant in the blind models.Our re sults show that the MLF(with an RMSE of 3.93 cm)and ET(3.99 cm)models outperform the traditional GPT3model(4.07 cm),while the RF(4.21 cm)and BPNN(4.14 cm)have worse external accuracies than the GPT3 model.It is worth noting that the BPNN suffered from overfitting during external accuracy tests,which was avoided by the MLF.In summary,regardless of the availability of surface meteorological data,the MLF-based empirical models demonstrate superior internal and external accuracy compared to the other tested models in this study.
基金supported by the National Natural Science Foundation of China(Nos.T2441002,22525506,U24A20137,and U22A6002)Strategic Priority Research Program of CAS(No.XDB0520101)+1 种基金National Key R&D Program of China(No.2023YFB3609000)CAS Project for Young Scientists in Basic Research(No.YSBR-053)。
文摘The increasing demand for flexible displays and wearable electronics has driven extensive efforts to develop stretchable organic lightemitting diodes(OLEDs).A critical challenge in this field is the creation of emissive layers that combine high efficiency with mechanical robustness.Thermally activated delayed fluorescence(TADF)materials have attracted significant attention as third-generation emitters capable of achieving 100%internal quantum efficiency;however,their application in stretchable OLEDs has been limited.In this study,we propose an elastomer doping strategy.Polyurethane(PU)is incorporated into TADF polymers to improve their mechanical flexibility while maintaining a high luminescent efficiency.The resulting composite films exhibited excellent TADF characteristics and remarkable stretchability(75%).OLEDs fabricated from these materials achieved a maximum external quantum efficiency(EQE)of 14.26%and a peak luminance of 73570 cd·m^(-2),with the PUdoped devices showing a significantly suppressed efficiency roll-off.Additionally,a fully stretchable OLED architecture was designed and operated under tensile strain to maintain stable electroluminescent performance.These results demonstrate that elastomer doping is an effective strategy for balancing the mechanical compliance with optoelectronic performance,offering a promising pathway for the development of high-performance stretchable OLEDs for flexible electronics.
基金supported by the National Natural Science Foundation of China,Nos.81701040(to HM),82071180(to HM),82271206(to TL),82171191(to YW),82371211(to YW)the Natural Science Foundation of Beijing,No.7212023(to HM)Key Subject of the Natural Science Foundation ofJiangsu Province for Colleges and Universities,No.23KJA320009(to YW).
文摘Delayed neurocognitive recovery following anesthesia and surgery is a common complication in older adult patients.Synapses are fundamental to cognitive function.The activity of synapses heavily depends on the energy supplied by synaptic mitochondria,which are significantly influenced by oxidative stress.Sirtuin 3 is a histone deacetylase located in the mitochondrial matrix that plays a pivotal role in regulating mitochondrial function.However,it remains unclear whether and how sirtuin 3 is involved in the development of delayed cognitive recovery.Therefore,in this study,we investigated the potential role of sirtuin 3 in synapses during delayed neurocognitive recovery.Our results showed that anesthesia and surgery induced cognitive impairment in mice and reduced sirtuin 3 protein expression.Overexpression of sirtuin 3 inhibited opening of the mitochondrial permeability transition pore by reducing acetylation of K166 on cyclophilin D and also rescued cognitive impairment.Aged mice carrying the cyclophilin D-K166R mutation exhibited significantly reduced cognitive impairment.Similarly,administering the mitochondrial permeability transition pore blocker,cyclosporine A,effectively alleviated the decline in synaptic mitochondrial function and cognitive impairment caused by anesthesia and surgery in aged mice.These results indicate that the sirtuin 3/cyclophilin D-K166/mPTP signaling pathway in hippocampal synaptic mitochondria is involved in delayed neurocognitive recovery of aged mice,suggesting this pathway could serve as a potential target for treatment.
基金supported by the National Natural Science Foundation of China (61703433)。
文摘Time delay and Doppler shift between the echo signal and the reference signal are two most commonly used measurements in target localization for the passive radar. Doppler rate, which can be obtained from the extended cross ambiguity function, offers an opportunity to further enhance the localization accuracy. This paper considers using the measurement Doppler rate in addition to measurements of time delay and Doppler shift to locate a moving target. A closed-form solution is developed to accurately and efficiently estimate the target position and velocity.The proposed solution establishes a pseudolinear set of equations by introducing some additional variables, imposes weighted least squares formulation to yield a rough estimate, and utilizes the function relation among the target location parameters and additional variables to improve the estimation accuracy. Theoretical covariance and Cramer-Rao lower bound(CRLB) are derived and compared, analytically indicating that the proposed solution attains the CRLB. Numerical simulations corroborate this analysis and demonstrate that the proposed solution outperforms existing methods.
文摘The proposed Doppler measurement technique shows that the Doppler measurements can be accomplished by a single pulse with multiple frequency components through optical fibre delay lines.Range and velocity ambiguity can be removed,and the velocity resolution can be improved dramatically by using long optical fibre delay lines.Furthermore,the velocity resolution can be modified by adjusting the length of optical fibre delay lines.In addition,the proposed radar can achieve high range resolution by using a single wideband pulse.As a result,the new approach can improve radar performance significantly.
文摘As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.
文摘Deep neural networks(DNNs)are effective in solving both forward and inverse problems for nonlinear partial differential equations(PDEs).However,conventional DNNs are not effective in handling problems such as delay differential equations(DDEs)and delay integrodifferential equations(DIDEs)with constant delays,primarily due to their low regularity at delayinduced breaking points.In this paper,a DNN method that combines multi-task learning(MTL)which is proposed to solve both the forward and inverse problems of DIDEs.The core idea of this approach is to divide the original equation into multiple tasks based on the delay,using auxiliary outputs to represent the integral terms,followed by the use of MTL to seamlessly incorporate the properties at the breaking points into the loss function.Furthermore,given the increased training dificulty associated with multiple tasks and outputs,we employ a sequential training scheme to reduce training complexity and provide reference solutions for subsequent tasks.This approach significantly enhances the approximation accuracy of solving DIDEs with DNNs,as demonstrated by comparisons with traditional DNN methods.We validate the effectiveness of this method through several numerical experiments,test various parameter sharing structures in MTL and compare the testing results of these structures.Finally,this method is implemented to solve the inverse problem of nonlinear DIDE and the results show that the unknown parameters of DIDE can be discovered with sparse or noisy data.
基金supported by the Natural Science Foundation of Hunan Province(2021JJ31089)the Scientific Research Project of Health Commission of Hunan Province(202203104548),China。
文摘Objective:The neurotoxicity of carbon monoxide(CO)to the central nervous system is a key pathogenesis of delayed encephalopathy after acute carbon monoxide poisoning(DEACMP).Our previous study found that retinoic acid(RA)can suppress the neurotoxic effects of CO.This study further explores,in vivo and in vitro,the molecular mechanisms by which RA alleviates CO-induced central nervous system damage.Methods:A cytotoxic model was established using the mouse hippocampal neuronal cell line HT22 and primary oligodendrocytes exposed to CO,and a DEACMP animal model was established in adult Kunming mice.Cell viability and apoptosis of hippocampal neurons and oligodendrocytes were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay and Annexin V/propidium iodide(PI)double staining.The transcriptional and protein expression of each gene was detected using real time fluorescence quantitative PCR(RT-qPCR)and Western blotting.Long noncoding RNA(lncRNA)SNHG15 and LINGO-1 were knocked down or overexpressed to observe changes in neurons and oligodendrocytes.In DEACMP mice,SNHG15 or LINGO-1 were knocked down to assess changes in central nervous tissue and downstream protein expression.Results:RA at 10 and 20μmol/L significantly reversed CO-induced apoptosis of hippocampal neurons and oligodendrocytes,downregulation of SNHG15 and LINGO-1,and upregulation of brain-derived neurotrophic factor(BDNF)and tyrosine kinase receptor B(TrkB)(all P<0.05).Overexpression of SNHG15 or LINGO-1 weakened the protective effect of RA against CO-induced cytotoxicity(all P<0.05).Knockdown of SNHG15 or LINGO-1 alleviated CO-induced apoptosis of hippocampal neurons and oligodendrocytes and upregulated BDNF and TrkB expression levels(all P<0.05).Experiments in DEACMP model mice showed that knockdown of SNHG15 or LINGO-1 mitigated central nervous system injury in DEACMP(all P<0.05).Conclusion:RA alleviates CO-induced apoptosis of hippocampal neurons and oligodendrocytes,thereby reducing central nervous system injury and exerting neuroprotective effects.LncRNA SNHG15 and LINGO-1 are key molecules mediating RA induced inhibition of neuronal apoptosis and are associated with the BDNF/TrkB pathway.These findings provide a theoretical framework for optimizing the clinical treatment of DEACMP and lay an experimental foundation for elucidating its molecular mechanisms.
基金supported by the National Natural Science Foundation of China under Grant U21A20449in part by Jiangsu Provincial Key Research and Development Program under Grant BE2021013-2。
文摘Wireless communication-enabled Cooperative Adaptive Cruise Control(CACC)is expected to improve the safety and traffic capacity of vehicle platoons.Existing CACC considers a conventional communication delay with fixed Vehicular Communication Network(VCN)topologies.However,when the network is under attack,the communication delay may be much higher,and the stability of the system may not be guaranteed.This paper proposes a novel communication Delay Aware CACC with Dynamic Network Topologies(DADNT).The main idea is that for various communication delays,in order to maximize the traffic capacity while guaranteeing stability and minimizing the following error,the CACC should dynamically adjust the VCN network topology to achieve the minimum inter-vehicle spacing.To this end,a multi-objective optimization problem is formulated,and a 3-step Divide-And-Conquer sub-optimal solution(3DAC)is proposed.Simulation results show that with 3DAC,the proposed DADNT with CACC can reduce the inter-vehicle spacing by 5%,10%,and 14%,respectively,compared with the traditional CACC with fixed one-vehicle,two-vehicle,and three-vehicle look-ahead network topologies,thereby improving the traffic efficiency.
基金supported by Fund of State Key Laboratory of IPOC(BUPT)(No.IPOC2021ZT16),China.
文摘The integrated optical true time delay phased array antenna system has the advantages of high bandwidth,small size,low loss and strong antiinterference capability,etc.The high integration of the optically controlled phased array antenna system is a necessary trend for the future development of the phased array,and it is also a major focus and difficulty in the current research of integrated microwave photonics.This paper firstly introduces the basic principle and development history of optical true time delay phased array antenna system based on microwave photonics,and briefly introduces the main implementation methods and integration platform of optical true time delay.Then,the application and development prospect of optical true time delay technology in beam control of phased array antenna system are mainly presented.Finally,according to the current research progress,the possible research directions of integrated optically controlled phased array antenna systems in the future are proposed.
基金supported by National Natural Science Foundation of China(No.61973234)Tianjin Science and Technology Plan Project(No.22YDTPJC00090)。
文摘To address the issue of low measurement accuracy caused by noise interference in the acquisition of low fluid flow rate signals with ultrasonic Doppler flow meters,a novel signal processing algorithm that combines ensemble empirical mode decomposition(EEMD)and cross-correlation algorithm was proposed.Firstly,a fast Fourier transform(FFT)spectrum analysis was utilized to ascertain the frequency range of the signal.Secondly,data acquisition was conducted at an appropriate sampling frequency,and the acquired Doppler flow rate signal was then decomposed into a series of intrinsic mode functions(IMFs)by EEMD.Subsequently,these decomposed IMFs were recombined based on their energy entropy,and then the noise of the recombined Doppler flow rate signal was removed by cross-correlation filtering.Finally,an ideal ultrasonic Doppler flow rate signal was extracted.Simulation and experimental verification show that the proposed Doppler flow signal processing method can effectively enhance the signal-to-noise ratio(SNR)and extend the lower limit of measurement of the ultrasonic Doppler flow meter.
基金Supported by the National Natural Science Foundation of China(12261050)Science and Technology Project of Department of Education of Jiangxi Province(GJJ2201612 and GJJ211027)Natural Science Foundation of Jiangxi Province of China(20212BAB202021)。
文摘In this paper,we investigate the periodic traveling wave solutions problem for a single population model with advection and distributed delay.By the bifurcation analysis method,we can obtain periodic traveling wave solutions for this model under the influence of advection term and distributed delay.The obtained results indicate that weak kernel and strong kernel can both deduce the existence of periodic traveling wave solutions.Finally,we apply the main results in this paper to Logistic model and Nicholson’s blowflies model.
