Advanced programmable metamaterials with heterogeneous microstructures have become increasingly prevalent in scientific and engineering disciplines attributed to their tunable properties.However,exploring the structur...Advanced programmable metamaterials with heterogeneous microstructures have become increasingly prevalent in scientific and engineering disciplines attributed to their tunable properties.However,exploring the structure-property relationship in these materials,including forward prediction and inverse design,presents substantial challenges.The inhomogeneous microstructures significantly complicate traditional analytical or simulation-based approaches.Here,we establish a novel framework that integrates the machine learning(ML)-encoded multiscale computational method for forward prediction and Bayesian optimization for inverse design.Unlike prior end-to-end ML methods limited to specific problems,our framework is both load-independent and geometry-independent.This means that a single training session for a constitutive model suffices to tackle various problems directly,eliminating the need for repeated data collection or training.We demonstrate the efficacy and efficiency of this framework using metamaterials with designable elliptical holes or lattice honeycombs microstructures.Leveraging accelerated forward prediction,we can precisely customize the stiffness and shape of metamaterials under diverse loading scenarios,and extend this capability to multi-objective customization seamlessly.Moreover,we achieve topology optimization for stress alleviation at the crack tip,resulting in a significant reduction of Mises stress by up to 41.2%and yielding a theoretical interpretable pattern.This framework offers a general,efficient and precise tool for analyzing the structure-property relationships of novel metamaterials.展开更多
The electrocatalytic reduction of carbon dioxide(CO_(2)ER)into formate presents a compelling solution for mitigating dependence on fossil energy and green utilization of CO_(2).Bismuth(Bi)has been gaining recognition ...The electrocatalytic reduction of carbon dioxide(CO_(2)ER)into formate presents a compelling solution for mitigating dependence on fossil energy and green utilization of CO_(2).Bismuth(Bi)has been gaining recognition as a promising catalyst material for the CO_(2)ER to formate.The performance of Bi catalysts(named as Bi-V)can be significantly improved when they possess single metal atom vacancy.However,creating larger-sized metal atom vacancies within Bi catalysts remains a significant challenge.In this work,Bi nanosheets with dual V0 Bi vacancy(Bi-DV)were synthesized utilizing in situ electrochemical transformation,using BiOBr nanosheets with triple vacancy associates(V■_(Bi)V··_(O)V■_(Bi),V■_(Bi)and V··_(O)denote the Bi^(3+)and O_(2)−vacancy,respectively)as a template.The obtained Bi-DV achieved higher CO_(2)ER activity than Bi-V,showing Faradaic efficiency for formate production of>92%from-0.9 to-1.2 VRHE in an H-type cell,and the partial current density of formate reached up to 755 mA/cm^(2)in a flow cell.The comprehensive characterizations coupled with density functional theory calculations demonstrate that the dual V^(0)_(Bi)vacancy on the surface of Bi-DV expedite the reaction kinetics toward CO_(2)ER,by reducing the thermodynamic barrier of^(∗)OCHO intermediate formation.This research provides critical insights into the potential of large atom vacancies to enhance electrocatalysis performance.展开更多
In the present study, we evaluated the antitumor, anti-tyrosinase, anti-pancreatic lipase, antibacterial, antifungal, and anti-α-glycosidase activities for all or a subset of 20 known compounds. They included 8 pheny...In the present study, we evaluated the antitumor, anti-tyrosinase, anti-pancreatic lipase, antibacterial, antifungal, and anti-α-glycosidase activities for all or a subset of 20 known compounds. They included 8 phenyl benzoates, 10 benzophenones, and 2 xanthones. Phenyl benzoate compounds 1–8 did not exhibit evident antitumor activity, which was consistent with existing theories. Compounds 16, 17, and 18 exhibited moderate anti-tyrosinase activity. In addition, compounds 11 and 18 exhibited moderate inhibitory activity against Candida albicans, and compound 20 exhibited stronger anti-α-glycosidase activity than quercetin, with an IC_(50)of approximately 2.45 μM. These results demonstrated that compounds 11, 16–18, and 20 were promising leads for further structural modification.展开更多
To achieve carbon neutrality,the Chinese government needs to gain a comprehensive understanding of the sources and drivers of greenhouse gas(GHG)emissions,particularly at the county level.Anji County in eastern China ...To achieve carbon neutrality,the Chinese government needs to gain a comprehensive understanding of the sources and drivers of greenhouse gas(GHG)emissions,particularly at the county level.Anji County in eastern China is a typical example of an industrial transformation from quarrying to a low-carbon economy.This study analyzed the decoupling types and structural characteristics of GHG emissions and the driving factors of carbon dioxide(CO_(2))emissions in the Anji from 2006 to 2019,and explored the differences between countylevel and provincial-level or city-level results.It was observed that energy-related activities are the main source of GHG emissions in Anji and that economic development is the driving factor behind the increasing CO_(2)emissions.However,industrial transformation and upgradation coupled with the alternative use of clean energy limit the growth of GHG emissions.This study details the GHG emissions of county during the industrial transformation stage and provides corresponding policy recommendations for county governments.展开更多
This article describes the physico-chemical characterization of the sulfated zirconia catalysts prepared from zirconyl chloride, acetic acid and ammonium persulfate system under structure-directing-free and calcined a...This article describes the physico-chemical characterization of the sulfated zirconia catalysts prepared from zirconyl chloride, acetic acid and ammonium persulfate system under structure-directing-free and calcined at 650°C. The catalysts were characterized via an array of characterization techniques such as surface acidity and texture measurements, X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), thermogravimetric measurement (TG) coupled with a quadrupole mass spectrometer (MS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and/or mass spectrometry (ICP-MS). It is clear from TG-MS, ICP-AES, and IR analyses that the precursor of the catalyst is a sulphur species-doped zirconium oxy-hydroxyl acetate complex. The presence of zirconium-bound sulfate groups results in the superacidity of the catalyst and hence high activity in n-hexane isomerization. It is shown from nitrogen adsorption and desorption, FESEM, and HRTEM measurements that the materials exhibit mesoporous and nanocrystalline structure.展开更多
To analyze the detection probability of shipbome AIS （automatic identification system） signal from space, a mathematical model dependent upon three factors of message collision avoidance, power of signal received by...To analyze the detection probability of shipbome AIS （automatic identification system） signal from space, a mathematical model dependent upon three factors of message collision avoidance, power of signal received by satellite and interference ratio of signal received is presented in the paper. The altitude and footprint area of the AIS satellite are discussed to overcome the collision of messages transmitted in the different time slots fxom different SOTDMA （self organizing time division multiple access） cell areas, but arrive at the same time slot due to the different signal path lengths. The simulated result shows that compared to the normal LEO （low ear~ orbit） satellite system, on average the maximum signal coverage area and the maximum FOV （field of view） of the AIS satellite system are reduced by 74% and 38%. The majority of power of signal transmitted fi＇om shipborne 12W-power AIS transmitters located within the maximum signal coverage area may be received with the sufficient margin of power of signal by the LEO satellite, but the space-based AIS system generally suffers from the insufficient CIR （carrier to co-channel interference ratio） of signal received since around 95% pairs of message simultaneously received by satellites may not be correctly decoded. The insufficient CIR of signal received is the bottleneck for the high message detection probability. Therefore, the measure of separating the collision messages should be further taken by the space-based AIS system to increase the detection probability.展开更多
Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limi...Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limited attention.Here,the“stair-building”strategy is employed in the rate domain by combining the bistability with viscoelasticity.An arbitrary target curve in the programmable space can be approximated by a“stair”built by two kinds of“bricks”.The“bricks”can be realized by a dual-bistable unit,constructed by two bistable structures in series.The dual-bistable unit can switch between two efficient stable phases without inducing changes in the global morphology.Such a unit exhibits N-shaped stress-strain curves at both efficient stable phases with different peak values,resulting in different heights of“bricks”.Moreover,the N-shaped curves have rate-dependent peak values,indicating that the heights of“bricks”change with loading rate.The“stair-building”strategy is realized by array-structured mechanical metamaterials based on dual-bistable units.Different stress-strain curves under various loading rates can be reprogrammed in the same piece of metamaterial by intentionally selecting the efficient stable phases of units.Besides,the rate effect of the metamaterial can also be tuned by reprogramming stress-strain curves under both low and high loading rates,respectively.This reprogrammable metamaterial is promising in smart vibration isolators and adaptive energy absorbers.展开更多
Recently,we developed a nonbuckling interconnect design that provides an effective approach to simultaneously achieving high elastic stretchability,easiness for encapsulation,and high electric performance for stretcha...Recently,we developed a nonbuckling interconnect design that provides an effective approach to simultaneously achieving high elastic stretchability,easiness for encapsulation,and high electric performance for stretchable electronics.This paper aims to systematically study its mechanical and electric behaviors,including comparisons of the nonbuckling and buckling interconnect designs on stretchability,effects of the thickness on electric performance,and modeling and experimental investigations on the finite deformation mechanics.It is found that the results on stretchability depend on the layouts.Long straight segments and small arc radii for nonbuckling interconnects yield an enhancement of stretchability,which is much better than that of buckling designs.On the other hand,shorter straight segments or thicker interconnects are better to lower the resistances of interconnects.Therefore,optimization of the designs needs to balance the requirements of both the mechanical and electric performances.The finite deformation of interconnects during stretching is analyzed.The established analytic model is well validated by both the finite element modeling and experimental investigations.This work is key for providing the design guidelines for nonbucklingbased stretchable electronics.展开更多
Optical networks are evolving toward ultrawide bandwidth and autonomous operation.In this scenario,it is crucial to accurately model and control optical power evolutions(OPEs)through optical amplifiers(OAs),as they di...Optical networks are evolving toward ultrawide bandwidth and autonomous operation.In this scenario,it is crucial to accurately model and control optical power evolutions(OPEs)through optical amplifiers(OAs),as they directly affect the signal-to-noise ratio and fiber nonlinearities.However,a fundamental contradiction arises between the complex physical phenomena in optical transmission and the required precision in network control.Traditional theoretical methods underperform due to ideal assumptions,while data-driven approaches entail exorbitant costs associated with acquiring massive amounts of data to achieve the desired level of accuracy.In this work,we propose a Bayesian inference framework(BIF)to construct the digital twin of OAs and control OPE in a data-efficient manner.Only the informative data are collected to balance the exploration and exploitation of the data space,thus enabling efficient autonomous-driving optical networks(ADONs).Simulations and experiments demonstrate that the BIF can reduce the data size for modeling erbium-doped fiber amplifiers by 80%and Raman amplifiers by 60%.Within 30 iterations,the optimal controlling performance can be achieved to realize target signal/gain profiles in links with different types of OAs.The results show that the BIF paves the way to accurately model and control OPE for future ADONs.展开更多
Self-locked energy-absorbing systems have been proposed in previous studies to overcome the limitations associated with the round-tube systems because they can prevent the lateral splash of tubes from impact loadings ...Self-locked energy-absorbing systems have been proposed in previous studies to overcome the limitations associated with the round-tube systems because they can prevent the lateral splash of tubes from impact loadings without any constraints.In case of self-locked systems,the ellipse-shaped self-locked tube is considered to be an optimal design when compared with the ordinary circle-shaped self-locked tubes and other shaped self-locked tubes.In this study,we aim to theoretically analyze the ellipseshaped self-locked tubes.Further,a plastic hinge model is developed to predict the force-displacement relation of the tube,which is compared with the deformation process observed in the experiment and finite element method(FEM)simulation.Using this model,the effects of tuning the geometric parameters of the tube on the energy absorption performance,including the deformation efficiency,energy absorption capacity,and effective stroke ratio,are simulated and analyzed.Finally,a guideline is provided with respect to the design of the ellipse-shaped self-locked tube in engineering applications.展开更多
Nanofiber networks are effective structural forms to utilize the excellent nanoscale properties of nanofibers in macro scale.Properly tuning the anisotropic degree of fiber orientation distribution can maximize the ma...Nanofiber networks are effective structural forms to utilize the excellent nanoscale properties of nanofibers in macro scale.Properly tuning the anisotropic degree of fiber orientation distribution can maximize the macroscopic mechanical properties of random nanofiber networks in a specific direction.However,the reinforcing mechanism of the anisotropic orientation distribution to the elastic behavior has not been fully understood.In this paper,the effect of anisotropic orientation distribution of nanofibers on the elastic behavior of network is studied based on the modulus-density scaling relation and stiffness thresholds.The uniaxial modulus of network is determined by both the orientation angle of each fiber and interconnectivity of the random fiber network.With the increase of anisotropic degree,the contribution of fiber orientation angle to the network modulus of the preferential direction increases and gradually tends to a constant,while the interconnectivity of the networks decreases,which may reduce the loadability of network.Therefore,at a given network density,the uniaxial modulus along the preferential direction first increases to a maximum value and then decreases with the increase of the anisotropic degree.Furthermore,an expression to predict the optimal anisotropic degrees corresponding to the maximum uniaxial moduli at different network densities is established.展开更多
To enhance adaptability in orchards with taller average tree heights and improve spraying effectiveness on Jinggang pomelo trees,this paper proposes a UAV-UGV cooperative targeted spraying system(UCTSS)and develops a ...To enhance adaptability in orchards with taller average tree heights and improve spraying effectiveness on Jinggang pomelo trees,this paper proposes a UAV-UGV cooperative targeted spraying system(UCTSS)and develops a prototype.The UCTSS primarily consists of a UAV and a UGV,networked using the Robot Operating System(ROS).During operation,both the UAV and UGV navigate between tree rows while carrying the spraying module.When the UAV reaches suitable spraying positions,the UGV halts to activate the spraying module,and the UAV performs targeted spraying from top to bottom.The paper employs a master-slave method for basic formation control of the UAV and UGV,resulting in an average tracking error of 0.118 m and a standard deviation of 0.040 m during testing.Additionally,a LiDAR-based targeted spraying detection method is designed and validated through simulation experiments,achieving an accuracy rate of 96%with an average position error of 0.13 m.Field trials in orchards demonstrate that the UCTSS meets stability requirements,with the average tracking error of the UAV measuring 0.158 m during coordinated movement and 0.013 m during spraying.In terms of spraying effectiveness,the UCTSS exhibits higher average droplet density and deposition values at various heights of the same tree compared to the DJI-T50,along with a lower coefficient of variation between levels,resulting in a more uniform spraying effect.The feasibility of the UCTSS is validated,providing a novel approach for orchard protection in areas with taller average tree heights.展开更多
Inspired by macroscale 3D pixel mechanical metamaterials and microscale straw-like carbon nanotube,we propose a design of multi-stable straw-like carbon nanotubes(MSCNT)via optimizing the structure of a unit to obtain...Inspired by macroscale 3D pixel mechanical metamaterials and microscale straw-like carbon nanotube,we propose a design of multi-stable straw-like carbon nanotubes(MSCNT)via optimizing the structure of a unit to obtain multiple stable states under dis-placement loading by molecular dynamics.The unit of MSCNT is mirror-symmetrically connected two truncated graphene cones with specific apex angles.By switching the LJ term in AIREBO potential,we verify that the bistability of unit is co-determined by snap-through instability and microscale adhesions.Moreover,we examine the validity of the multi-stability of the unit cells arranged in series and in parallels.Simulation results indicate that the MSCNT can achieve mechanical programmability in microscale,which triggers many potential applications in need of customizing nanos-cale mechanical behaviors.展开更多
An in-band optical signal-to-noise ratio （OSNR） monitoring technique with high resolution and large measurement range is demonstrated based on low- bandwidth coherent receiver and a tunable laser. The measurement ra...An in-band optical signal-to-noise ratio （OSNR） monitoring technique with high resolution and large measurement range is demonstrated based on low- bandwidth coherent receiver and a tunable laser. The measurement range of OSNR is from 10 to 25 dB and the resolution can be controlled about ±1 dB.展开更多
Immunohistochemistry(IHC)is a vital technique for detecting specific proteins and antigens in tissue sections using antibodies,aiding in the analysis of tumor growth and metastasis.However,IHC is costly and time-consu...Immunohistochemistry(IHC)is a vital technique for detecting specific proteins and antigens in tissue sections using antibodies,aiding in the analysis of tumor growth and metastasis.However,IHC is costly and time-consuming,making it challenging to implement on a large scale.To address this issue,we introduce a method that enables virtual IHC staining directly on Hematoxylin and Eosin(H&E)images.Firstly,we have developed a novel registration technique,called Bi-stage Registration based on density Clustering(BiReC),to enhance the registration efficiency between H&E and IHC images.This method involves automatically generating numerous Regions Of Interest(ROI)labels on the H&E image for model training,with the labels being determined by the intensity of IHC staining.Secondly,we propose a novel two-branch network architecture,called SeaConvNeXt,which integrates a lightweight Squeeze-Enhanced Axial(SEA)attention mechanism to efficiently extract and fuse multi-level local and global features from H&E images for direct prediction of specific proteins and antigens.The SeaConvNeXt consists of a ConvNeXt branch and a global fusion branch.The ConvNeXt branch extracts multi-level local features at four stages,while the global fusion branch,including an SEA Transformer module and three global blocks,is designed for global feature extraction and multiple feature fusion.Our experiments demonstrate that SeaConvNeXt outperforms current state-of-the-art methods on two public datasets with corresponding IHC and H&E images,achieving an AUC of 90.7%on the HER2SC dataset and 82.5%on the CRC dataset.These results suggest that SeaConvNeXt has great potential for predicting virtual IHC staining on H&E images.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12102021,12372105,12172026,and 12225201)the Fundamental Research Funds for the Central Universities and the Academic Excellence Foundation of BUAA for PhD Students.
文摘Advanced programmable metamaterials with heterogeneous microstructures have become increasingly prevalent in scientific and engineering disciplines attributed to their tunable properties.However,exploring the structure-property relationship in these materials,including forward prediction and inverse design,presents substantial challenges.The inhomogeneous microstructures significantly complicate traditional analytical or simulation-based approaches.Here,we establish a novel framework that integrates the machine learning(ML)-encoded multiscale computational method for forward prediction and Bayesian optimization for inverse design.Unlike prior end-to-end ML methods limited to specific problems,our framework is both load-independent and geometry-independent.This means that a single training session for a constitutive model suffices to tackle various problems directly,eliminating the need for repeated data collection or training.We demonstrate the efficacy and efficiency of this framework using metamaterials with designable elliptical holes or lattice honeycombs microstructures.Leveraging accelerated forward prediction,we can precisely customize the stiffness and shape of metamaterials under diverse loading scenarios,and extend this capability to multi-objective customization seamlessly.Moreover,we achieve topology optimization for stress alleviation at the crack tip,resulting in a significant reduction of Mises stress by up to 41.2%and yielding a theoretical interpretable pattern.This framework offers a general,efficient and precise tool for analyzing the structure-property relationships of novel metamaterials.
基金supported by the National Natural Science Foundation of China(Nos.22276064 and 22278168)the Open Research Fund of Academy of Advanced Carbon Conversion Technology of Huaqiao University(No.AACCT0003)the Science and Technology Project of Fujian province(No.2022Y3007).
文摘The electrocatalytic reduction of carbon dioxide(CO_(2)ER)into formate presents a compelling solution for mitigating dependence on fossil energy and green utilization of CO_(2).Bismuth(Bi)has been gaining recognition as a promising catalyst material for the CO_(2)ER to formate.The performance of Bi catalysts(named as Bi-V)can be significantly improved when they possess single metal atom vacancy.However,creating larger-sized metal atom vacancies within Bi catalysts remains a significant challenge.In this work,Bi nanosheets with dual V0 Bi vacancy(Bi-DV)were synthesized utilizing in situ electrochemical transformation,using BiOBr nanosheets with triple vacancy associates(V■_(Bi)V··_(O)V■_(Bi),V■_(Bi)and V··_(O)denote the Bi^(3+)and O_(2)−vacancy,respectively)as a template.The obtained Bi-DV achieved higher CO_(2)ER activity than Bi-V,showing Faradaic efficiency for formate production of>92%from-0.9 to-1.2 VRHE in an H-type cell,and the partial current density of formate reached up to 755 mA/cm^(2)in a flow cell.The comprehensive characterizations coupled with density functional theory calculations demonstrate that the dual V^(0)_(Bi)vacancy on the surface of Bi-DV expedite the reaction kinetics toward CO_(2)ER,by reducing the thermodynamic barrier of^(∗)OCHO intermediate formation.This research provides critical insights into the potential of large atom vacancies to enhance electrocatalysis performance.
基金Natural Science Foundation of Fujian Province (Grant No. 2022J011158)Putian City Science and Technology Plan Project (Grant No. 2021S2001-9)Fujian Provincial Key Laboratory of Innovative Drug Target Research (Grant No. FJ-YW-2021KF01)。
文摘In the present study, we evaluated the antitumor, anti-tyrosinase, anti-pancreatic lipase, antibacterial, antifungal, and anti-α-glycosidase activities for all or a subset of 20 known compounds. They included 8 phenyl benzoates, 10 benzophenones, and 2 xanthones. Phenyl benzoate compounds 1–8 did not exhibit evident antitumor activity, which was consistent with existing theories. Compounds 16, 17, and 18 exhibited moderate anti-tyrosinase activity. In addition, compounds 11 and 18 exhibited moderate inhibitory activity against Candida albicans, and compound 20 exhibited stronger anti-α-glycosidase activity than quercetin, with an IC_(50)of approximately 2.45 μM. These results demonstrated that compounds 11, 16–18, and 20 were promising leads for further structural modification.
基金supported by the National Natural Science Foundation of China(Nos.22278168 and 22276064)the MOE Key Laboratory of Resources and Environmental System Optimization(No.KLRE-KF202205)the Science and Technology Project of Fujian province(No.2022Y3007)。
文摘To achieve carbon neutrality,the Chinese government needs to gain a comprehensive understanding of the sources and drivers of greenhouse gas(GHG)emissions,particularly at the county level.Anji County in eastern China is a typical example of an industrial transformation from quarrying to a low-carbon economy.This study analyzed the decoupling types and structural characteristics of GHG emissions and the driving factors of carbon dioxide(CO_(2))emissions in the Anji from 2006 to 2019,and explored the differences between countylevel and provincial-level or city-level results.It was observed that energy-related activities are the main source of GHG emissions in Anji and that economic development is the driving factor behind the increasing CO_(2)emissions.However,industrial transformation and upgradation coupled with the alternative use of clean energy limit the growth of GHG emissions.This study details the GHG emissions of county during the industrial transformation stage and provides corresponding policy recommendations for county governments.
文摘This article describes the physico-chemical characterization of the sulfated zirconia catalysts prepared from zirconyl chloride, acetic acid and ammonium persulfate system under structure-directing-free and calcined at 650°C. The catalysts were characterized via an array of characterization techniques such as surface acidity and texture measurements, X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), thermogravimetric measurement (TG) coupled with a quadrupole mass spectrometer (MS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and/or mass spectrometry (ICP-MS). It is clear from TG-MS, ICP-AES, and IR analyses that the precursor of the catalyst is a sulphur species-doped zirconium oxy-hydroxyl acetate complex. The presence of zirconium-bound sulfate groups results in the superacidity of the catalyst and hence high activity in n-hexane isomerization. It is shown from nitrogen adsorption and desorption, FESEM, and HRTEM measurements that the materials exhibit mesoporous and nanocrystalline structure.
文摘To analyze the detection probability of shipbome AIS （automatic identification system） signal from space, a mathematical model dependent upon three factors of message collision avoidance, power of signal received by satellite and interference ratio of signal received is presented in the paper. The altitude and footprint area of the AIS satellite are discussed to overcome the collision of messages transmitted in the different time slots fxom different SOTDMA （self organizing time division multiple access） cell areas, but arrive at the same time slot due to the different signal path lengths. The simulated result shows that compared to the normal LEO （low ear~ orbit） satellite system, on average the maximum signal coverage area and the maximum FOV （field of view） of the AIS satellite system are reduced by 74% and 38%. The majority of power of signal transmitted fi＇om shipborne 12W-power AIS transmitters located within the maximum signal coverage area may be received with the sufficient margin of power of signal by the LEO satellite, but the space-based AIS system generally suffers from the insufficient CIR （carrier to co-channel interference ratio） of signal received since around 95% pairs of message simultaneously received by satellites may not be correctly decoded. The insufficient CIR of signal received is the bottleneck for the high message detection probability. Therefore, the measure of separating the collision messages should be further taken by the space-based AIS system to increase the detection probability.
基金supported by the National Natural Science Foundation of China(Grant Nos.12225201,12372126,12002016,and 12172026)the National Key Research and Development Program of China(Grant No.2020YFB1313003)the Fundamental Research Funds for the Central Universities are gratefully acknowledged.
文摘Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limited attention.Here,the“stair-building”strategy is employed in the rate domain by combining the bistability with viscoelasticity.An arbitrary target curve in the programmable space can be approximated by a“stair”built by two kinds of“bricks”.The“bricks”can be realized by a dual-bistable unit,constructed by two bistable structures in series.The dual-bistable unit can switch between two efficient stable phases without inducing changes in the global morphology.Such a unit exhibits N-shaped stress-strain curves at both efficient stable phases with different peak values,resulting in different heights of“bricks”.Moreover,the N-shaped curves have rate-dependent peak values,indicating that the heights of“bricks”change with loading rate.The“stair-building”strategy is realized by array-structured mechanical metamaterials based on dual-bistable units.Different stress-strain curves under various loading rates can be reprogrammed in the same piece of metamaterial by intentionally selecting the efficient stable phases of units.Besides,the rate effect of the metamaterial can also be tuned by reprogramming stress-strain curves under both low and high loading rates,respectively.This reprogrammable metamaterial is promising in smart vibration isolators and adaptive energy absorbers.
基金supported by the National Natural Science Foundation of China(Grant Nos.11572323,11772331,11302038,51365013,and 11732004)the Chinese Academy of Sciences via the"Hundred Talent Program"+8 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB22040501)the State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian University of Technology(Grant No.GZ1603)the State Key Laboratory of Digital Manufacturing Equipment and Technology,Huazhong University of Science and Technology(Grant No.DMETKF2017008)the Young Elite Scientists Sponsorship Program by CAST(Grant No.2015QNRC001)the Opening Fund of State Key Laboratory of Nonlinear Mechanicsthe Personnel Training Plan of Tianjin City in China for the Key Young and Middle-Aged Innovation Talentsthe National Key Research and Development Plan(Grant Nos.2016YFB0201600,2016YFB0201601,2017YFB0202800,and 2017YFB0202802)the Program for Changjiang Scholars,Innovative Research Team in University(PCSIRT)the 111 Project(Grant No.B14013)
文摘Recently,we developed a nonbuckling interconnect design that provides an effective approach to simultaneously achieving high elastic stretchability,easiness for encapsulation,and high electric performance for stretchable electronics.This paper aims to systematically study its mechanical and electric behaviors,including comparisons of the nonbuckling and buckling interconnect designs on stretchability,effects of the thickness on electric performance,and modeling and experimental investigations on the finite deformation mechanics.It is found that the results on stretchability depend on the layouts.Long straight segments and small arc radii for nonbuckling interconnects yield an enhancement of stretchability,which is much better than that of buckling designs.On the other hand,shorter straight segments or thicker interconnects are better to lower the resistances of interconnects.Therefore,optimization of the designs needs to balance the requirements of both the mechanical and electric performances.The finite deformation of interconnects during stretching is analyzed.The established analytic model is well validated by both the finite element modeling and experimental investigations.This work is key for providing the design guidelines for nonbucklingbased stretchable electronics.
基金supported by the Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University(Grant No.21TQ1400213)the National Natural Science Foundation of China(Grant No.62175145)
文摘Optical networks are evolving toward ultrawide bandwidth and autonomous operation.In this scenario,it is crucial to accurately model and control optical power evolutions(OPEs)through optical amplifiers(OAs),as they directly affect the signal-to-noise ratio and fiber nonlinearities.However,a fundamental contradiction arises between the complex physical phenomena in optical transmission and the required precision in network control.Traditional theoretical methods underperform due to ideal assumptions,while data-driven approaches entail exorbitant costs associated with acquiring massive amounts of data to achieve the desired level of accuracy.In this work,we propose a Bayesian inference framework(BIF)to construct the digital twin of OAs and control OPE in a data-efficient manner.Only the informative data are collected to balance the exploration and exploitation of the data space,thus enabling efficient autonomous-driving optical networks(ADONs).Simulations and experiments demonstrate that the BIF can reduce the data size for modeling erbium-doped fiber amplifiers by 80%and Raman amplifiers by 60%.Within 30 iterations,the optimal controlling performance can be achieved to realize target signal/gain profiles in links with different types of OAs.The results show that the BIF paves the way to accurately model and control OPE for future ADONs.
基金the National Natural Science Foundation of China(Grant Nos.11622214,11472027,and 11202012)the Academic Excellence Foundation of Beihang University for PhD Students。
文摘Self-locked energy-absorbing systems have been proposed in previous studies to overcome the limitations associated with the round-tube systems because they can prevent the lateral splash of tubes from impact loadings without any constraints.In case of self-locked systems,the ellipse-shaped self-locked tube is considered to be an optimal design when compared with the ordinary circle-shaped self-locked tubes and other shaped self-locked tubes.In this study,we aim to theoretically analyze the ellipseshaped self-locked tubes.Further,a plastic hinge model is developed to predict the force-displacement relation of the tube,which is compared with the deformation process observed in the experiment and finite element method(FEM)simulation.Using this model,the effects of tuning the geometric parameters of the tube on the energy absorption performance,including the deformation efficiency,energy absorption capacity,and effective stroke ratio,are simulated and analyzed.Finally,a guideline is provided with respect to the design of the ellipse-shaped self-locked tube in engineering applications.
基金the National Natural Science Foundation of China[12002016,12172026,2225201]the National Key Research and Development Program of China[2020YFB1313003]+1 种基金China Postdoctoral Science Foundation[2020M680288]National Postdoctoral Program for Innovative Talents[BX20200032].
文摘Nanofiber networks are effective structural forms to utilize the excellent nanoscale properties of nanofibers in macro scale.Properly tuning the anisotropic degree of fiber orientation distribution can maximize the macroscopic mechanical properties of random nanofiber networks in a specific direction.However,the reinforcing mechanism of the anisotropic orientation distribution to the elastic behavior has not been fully understood.In this paper,the effect of anisotropic orientation distribution of nanofibers on the elastic behavior of network is studied based on the modulus-density scaling relation and stiffness thresholds.The uniaxial modulus of network is determined by both the orientation angle of each fiber and interconnectivity of the random fiber network.With the increase of anisotropic degree,the contribution of fiber orientation angle to the network modulus of the preferential direction increases and gradually tends to a constant,while the interconnectivity of the networks decreases,which may reduce the loadability of network.Therefore,at a given network density,the uniaxial modulus along the preferential direction first increases to a maximum value and then decreases with the increase of the anisotropic degree.Furthermore,an expression to predict the optimal anisotropic degrees corresponding to the maximum uniaxial moduli at different network densities is established.
基金supported by Science and Technology Plan of Ji’an City of China(Grant No.20211-055316 and[2020]83)in part by the Laboratory of Lingnan Modern Agriculture Project(Grant No.NT2021009)+1 种基金Science and Technology Plan of Guangdong Province of China(Grant No.2023B10564002)China Scholarship Council(Grant No.202308440394)。
文摘To enhance adaptability in orchards with taller average tree heights and improve spraying effectiveness on Jinggang pomelo trees,this paper proposes a UAV-UGV cooperative targeted spraying system(UCTSS)and develops a prototype.The UCTSS primarily consists of a UAV and a UGV,networked using the Robot Operating System(ROS).During operation,both the UAV and UGV navigate between tree rows while carrying the spraying module.When the UAV reaches suitable spraying positions,the UGV halts to activate the spraying module,and the UAV performs targeted spraying from top to bottom.The paper employs a master-slave method for basic formation control of the UAV and UGV,resulting in an average tracking error of 0.118 m and a standard deviation of 0.040 m during testing.Additionally,a LiDAR-based targeted spraying detection method is designed and validated through simulation experiments,achieving an accuracy rate of 96%with an average position error of 0.13 m.Field trials in orchards demonstrate that the UCTSS meets stability requirements,with the average tracking error of the UAV measuring 0.158 m during coordinated movement and 0.013 m during spraying.In terms of spraying effectiveness,the UCTSS exhibits higher average droplet density and deposition values at various heights of the same tree compared to the DJI-T50,along with a lower coefficient of variation between levels,resulting in a more uniform spraying effect.The feasibility of the UCTSS is validated,providing a novel approach for orchard protection in areas with taller average tree heights.
基金the National Natural Science Foundation of China(Nos.12225201 and 12102021)the China Postdoctoral Science Foundation(No.2020M680287)are gratefully acknowledged.
文摘Inspired by macroscale 3D pixel mechanical metamaterials and microscale straw-like carbon nanotube,we propose a design of multi-stable straw-like carbon nanotubes(MSCNT)via optimizing the structure of a unit to obtain multiple stable states under dis-placement loading by molecular dynamics.The unit of MSCNT is mirror-symmetrically connected two truncated graphene cones with specific apex angles.By switching the LJ term in AIREBO potential,we verify that the bistability of unit is co-determined by snap-through instability and microscale adhesions.Moreover,we examine the validity of the multi-stability of the unit cells arranged in series and in parallels.Simulation results indicate that the MSCNT can achieve mechanical programmability in microscale,which triggers many potential applications in need of customizing nanos-cale mechanical behaviors.
基金Acknowledgements The authors would like to acknowledge the support of the National Natural Science Foundation of China （NSFC） （Grant No. 61435006） and the Program for New Century Excellent Talents in University （NCET-12-0679） in China.
文摘An in-band optical signal-to-noise ratio （OSNR） monitoring technique with high resolution and large measurement range is demonstrated based on low- bandwidth coherent receiver and a tunable laser. The measurement range of OSNR is from 10 to 25 dB and the resolution can be controlled about ±1 dB.
基金supported by the National Key R&D Program of China(No.2023YFC3402800)the National Natural Science Foundation of China(Nos.62371276,62272288,and 82272084)the Fundamental Research Funds for the Central Universities,Shaanxi Normal University(No.GK202302006).
文摘Immunohistochemistry(IHC)is a vital technique for detecting specific proteins and antigens in tissue sections using antibodies,aiding in the analysis of tumor growth and metastasis.However,IHC is costly and time-consuming,making it challenging to implement on a large scale.To address this issue,we introduce a method that enables virtual IHC staining directly on Hematoxylin and Eosin(H&E)images.Firstly,we have developed a novel registration technique,called Bi-stage Registration based on density Clustering(BiReC),to enhance the registration efficiency between H&E and IHC images.This method involves automatically generating numerous Regions Of Interest(ROI)labels on the H&E image for model training,with the labels being determined by the intensity of IHC staining.Secondly,we propose a novel two-branch network architecture,called SeaConvNeXt,which integrates a lightweight Squeeze-Enhanced Axial(SEA)attention mechanism to efficiently extract and fuse multi-level local and global features from H&E images for direct prediction of specific proteins and antigens.The SeaConvNeXt consists of a ConvNeXt branch and a global fusion branch.The ConvNeXt branch extracts multi-level local features at four stages,while the global fusion branch,including an SEA Transformer module and three global blocks,is designed for global feature extraction and multiple feature fusion.Our experiments demonstrate that SeaConvNeXt outperforms current state-of-the-art methods on two public datasets with corresponding IHC and H&E images,achieving an AUC of 90.7%on the HER2SC dataset and 82.5%on the CRC dataset.These results suggest that SeaConvNeXt has great potential for predicting virtual IHC staining on H&E images.
