Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor strugg...Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix,and achieving sensitivity for detecting micrometer-scale deformations is also challenging.Herein,we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement,capable of detecting minute anisotropic deformations.The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%,thereby enabling its utility in accurately discerning the 5μm-height wrinkles in thin films and in monitoring human pulse waves.The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase.Additionally,when integrated with machine learning techniques,the sensor’s capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100%accuracy.The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli,offering a novel perspective for enhancing recognition accuracy.展开更多
For constructing next-generation lithium-ion batteries with advanced performances,pursuit of highcapacity Li-rich cathodes has caused considerable attention.So far,the low discharge specific capacity and serious capac...For constructing next-generation lithium-ion batteries with advanced performances,pursuit of highcapacity Li-rich cathodes has caused considerable attention.So far,the low discharge specific capacity and serious capacity fading are strangling the development of Fe-based Li-rich materials.To activate the extra-capacity of Fe-based Li-rich cathode materials,a facile molten salt method is exploited using an alkaline mixture of LiOH–LiNO3–Li2O2 in this work.The prepared Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2 material yields high discharge specific capacity and good cycling stability.The discharge specific capacity shows an upward tendency at 0.1 C.After 60 cycles,a high reversible specific capacity of ~250 m Ah g-1is delivered.The redox of Fe3+/Fe4+and Mn3+/Mn4+are gradually activated during cycling.Notably,the redox reaction of Fe2+/Fe3+can be observed reversibly below 2 V,which is quite different from the material prepared by a traditional co-precipitation method.The stable morphology of fine nanoparticles(100–300 nm)is considered benefiting for the distinctive electrochemical performances of Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2.This study demonstrates that molten salt method is an inexpensive and effective approach to activate the extra capacity of Fe-based Li-rich cathode material for high-performance lithium-ion batteries.展开更多
The objective of this paper is to investigate the question of modifying a givengeneralized Bessel sequence to yield a generalized frame or a tight generalized frame by finiteextension. Some necessary and sufficient co...The objective of this paper is to investigate the question of modifying a givengeneralized Bessel sequence to yield a generalized frame or a tight generalized frame by finiteextension. Some necessary and sufficient conditions for the finite extensions of generalizedBessel sequences to generalized frames or tight generalized frames are provided, and everyresult is illustrated by the corresponding example.展开更多
Techniques for predicting the trajectory of vulnerable road users are important to the development of perception systems for autonomous vehicles to avoid accidents.The most effective trajectory prediction methods,such...Techniques for predicting the trajectory of vulnerable road users are important to the development of perception systems for autonomous vehicles to avoid accidents.The most effective trajectory prediction methods,such as Social-LSTM,are often used to predict pedestrian trajectories in normal passage scenarios.However,they can produce unsatisfactory prediction results and data redundancy,as well as difficulties in predicting trajectories using pixel-based coordinate systems in collision avoidance systems.There is also a lack of validations using real vehicle-to-pedestrian collisions.To address these issues,some insightful approaches to improve the trajectory prediction scheme of Social-LSTM were proposed,such methods included transforming pedestrian trajectory coordinates and converting image coordinates to world coordinates.The YOLOv5 detection model was introduced to reduce target loss and improve prediction accuracy.The DeepSORT algorithm was employed to reduce the number of target transformations in the tracking model.Image Perspective Transformation(IPT)and Direct Linear Transformation(DLT)theories were combined to transform the coordinates to world coordinates,identifying the collision location where the accident could occur.The performance of the proposed method was validated by training tests using MS COCO(Microsoft Common Objects in Context)and ETH/UCY datasets.The results showed that the target detection accuracy was more than 90%and the prediction loss tends to decrease with increasing training steps,with the final loss value less than 1%.The reliability and effectiveness of the improved method were demonstrated by benchmarking system performance to two video recordings of real pedestrian accidents with different lighting conditions.展开更多
In order to determine the optimal sowing date of ratoon rice in South Henan's rice-growing areas,this paper performs a comparative analysis of rice growth process,seedling quality and yield of first season rice an...In order to determine the optimal sowing date of ratoon rice in South Henan's rice-growing areas,this paper performs a comparative analysis of rice growth process,seedling quality and yield of first season rice and ratoon rice under different sowing date treatments. The results show that under climatic conditions( 2014),by using dry seedling cultivation in a small plastic shed,the growth of seedling sown on February21 was affected,while the sowing treatments from March 1 to April 11 can breed normal seedlings,and in this period,the maturity period of first season rice was delayed with prolonged sowing date,and ratoon rice yield declined with prolonged sowing date( total production of rice sown on 11 March reaching a peak). Thus,it is considered that the optimal sowing date of ratoon rice in South Henan's rice-growing areas is mid-March.展开更多
[Objectives] This study aimed to study the morphological characteristics and molecular phylogeny of a new strain collected from rotten wood of sea buckthorn in Yanbei area of Shanxi Province. [Methods]The specimens we...[Objectives] This study aimed to study the morphological characteristics and molecular phylogeny of a new strain collected from rotten wood of sea buckthorn in Yanbei area of Shanxi Province. [Methods]The specimens were observed with naked eyes. With Melzer,cotton blue and 5% KOH as floating carriers,the slices were prepared,which were observed under a microscope. The ITS sequence of the new strain was compared with those of the 20 kinds of reported fungi to construct molecular phylogenetic tree based on ITS. [Results] The new strain has horseshoe-shaped basidiocarp and pileus shape and has no stipe. Sometimes,it grows procumbently and scrolled backward. The mycelial system is monomitic. The skeletal hyphae showed a negative reaction in the Melzer reagent and cotton blue reagent. The basidiospores are subglobose or spherical and colorless with thick wall. The results of molecular phylogenetic analysis showed that the new strain had a close relationship with Fomitiporia spp. and was clustered into the same branch with them. It formed an independent sub-branch in the phylogenetic tree. [Conclusions] The new strain was identified as a new species of Fomitiporia,named as Fomitiporia yanbeiensis S. Guo & L. Zhou( Gen Bank: KT861405,Fungal name: FN570360).展开更多
The competition between the RKKY interaction and the Kondo effect leads to a magnetic phase transition,which occurs ubiquitously in heavy fermion materials.However,there are more and more experimental evidences indica...The competition between the RKKY interaction and the Kondo effect leads to a magnetic phase transition,which occurs ubiquitously in heavy fermion materials.However,there are more and more experimental evidences indicating that the valence fluctuation plays an essential role in the Ce-and Y-based compounds.We study an extended periodic Anderson model(EPAM)which includes the onsite Coulomb repulsion Ucf between the localized electrons and conduction electrons.By employing the density matrix embedding theory,we investigate the EPAM in the symmetric case at half filling.By fixing the onsite Coulomb repulsion U of the localized electrons to an intermediate value,the interplay between the RKKY interaction,the Kondo effect and the Coulomb repulsion Ucf brings rich physics.We find three different phases,the antiferromagnetic phase,the charge order phase and paramagnetic phase.When the hybridization strength V between the localized orbital and the conduction orbital is small,the Kondo effect is weak so that the AF phase and the CO phase are present.The phase transition between the two long-range ordered phase is of first order.We also find a coexistence region between the two phases.As V increases,the Kondo effect becomes stronger,and the paramagnetic phase appears between the other two phases.展开更多
In this study, controlled-release fertilizers （CRFs） with five different nitrogen release periods were pre- pared by coating large urea particles with polyethylene （PE） membranes under various experimental conditi...In this study, controlled-release fertilizers （CRFs） with five different nitrogen release periods were pre- pared by coating large urea particles with polyethylene （PE） membranes under various experimental conditions. The preliminary and differential solubility rates, release periods, and membrane pore sizes of the obtained CRFs were measured using water immersion, scanning electron microscopy, and mercury porosimetry. For all CRF samples, the median pore diameters of the membranes were equal to 4.5-5.3 nm and pores with sizes smaller than 10 nm accounted for 86-96% of the total pore surface area. The obtained pore diameter distributions differed for the five studied types of CRF, having release periods of 1,2, 4, 6, and 8 months. Thus, for the CRFs with a 1-month release period, the maximum pore diameter reached a magnitude of 4000 nm, while this value did not exceed 30 nm for the CRFs with a release period of 8 months. Hence, we have established a relationship between the release period of CRFs and their effective maximum pore sizes.展开更多
Condition-based maintenance(CBM)detects early signs of failure and dictates when maintenance should be performed based on the actual condition of a system.In this paper,we first review some of the recent research on C...Condition-based maintenance(CBM)detects early signs of failure and dictates when maintenance should be performed based on the actual condition of a system.In this paper,we first review some of the recent research on CBM under various physical structures and signal data.Then,we summarize several kinds of prognostic models that use monitoring information to estimate the reliability of complex systems or products.Monitoring information also facilitates operational decisions in production planning,spare parts management,reliability improvement,and prognostics and health management.Finally,we suggest some research opportunities for the reliability and operations management communities to fill the research gap between these two fields.展开更多
Facing the threat of market follower encroachment,this paper constructs game theoretical models based on different channel structures and market structures,investigates following manufacturer's encroachment strate...Facing the threat of market follower encroachment,this paper constructs game theoretical models based on different channel structures and market structures,investigates following manufacturer's encroachment strategy and technology strategies,and discusses the impact of following manufacturer's strategy on quality decisions.The results show that encroachment always improves consumer surplus by slashing prices when leading manufacturer adopts in-house R&D(IRD);otherwise,it results in lower consumer surplus with mild competition if leading manufacturer is at a technological disadvantage.Furthermore,the technology strategies of following manufacturer are related to their R&D capabilities.The superior one is outsourcing R&D(ORD)for the manufacturers when their R&D capability is weak,otherwise,IRD is optimal.In a word,the leading manufacturer always prefers IRD under certain conditions,while the following manufacturer always prefers ORD.In addition,encroachment restrains quality innovative motivation under fixed or quality-sensitive R&D costs,but can improve quality level when consumers have a higher reference dependency for quality;meanwhile,the following manufacturer adopting ORD is always beneficial to quality improvement.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2022YFA1205300 and No.2022YFA1205304)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(SL2022ZD103).
文摘Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix,and achieving sensitivity for detecting micrometer-scale deformations is also challenging.Herein,we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement,capable of detecting minute anisotropic deformations.The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%,thereby enabling its utility in accurately discerning the 5μm-height wrinkles in thin films and in monitoring human pulse waves.The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase.Additionally,when integrated with machine learning techniques,the sensor’s capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100%accuracy.The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli,offering a novel perspective for enhancing recognition accuracy.
基金supported by the Nature Science Foundations of Hebei Province (B2016210071, B2016210111)the Natural Science Foundation of Hebei Education Department (QN2016057, ZD2015082, ZC2016045)+3 种基金the National College Students’ Innovative Entrepreneurial Training Project of Chinasupported by the Chinese National 973 Program (2015CB251106)the Joint Funds of the National Natural Science Foundation of China (U1564206)Major achievements Transformation Project for Central University in Beijing
文摘For constructing next-generation lithium-ion batteries with advanced performances,pursuit of highcapacity Li-rich cathodes has caused considerable attention.So far,the low discharge specific capacity and serious capacity fading are strangling the development of Fe-based Li-rich materials.To activate the extra-capacity of Fe-based Li-rich cathode materials,a facile molten salt method is exploited using an alkaline mixture of LiOH–LiNO3–Li2O2 in this work.The prepared Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2 material yields high discharge specific capacity and good cycling stability.The discharge specific capacity shows an upward tendency at 0.1 C.After 60 cycles,a high reversible specific capacity of ~250 m Ah g-1is delivered.The redox of Fe3+/Fe4+and Mn3+/Mn4+are gradually activated during cycling.Notably,the redox reaction of Fe2+/Fe3+can be observed reversibly below 2 V,which is quite different from the material prepared by a traditional co-precipitation method.The stable morphology of fine nanoparticles(100–300 nm)is considered benefiting for the distinctive electrochemical performances of Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2.This study demonstrates that molten salt method is an inexpensive and effective approach to activate the extra capacity of Fe-based Li-rich cathode material for high-performance lithium-ion batteries.
基金partially supported by the National Natural Science Foundation of China(61471410)
文摘The objective of this paper is to investigate the question of modifying a givengeneralized Bessel sequence to yield a generalized frame or a tight generalized frame by finiteextension. Some necessary and sufficient conditions for the finite extensions of generalizedBessel sequences to generalized frames or tight generalized frames are provided, and everyresult is illustrated by the corresponding example.
基金support of the Natural Science Foundation of China(Grant No.51775466)the Xiamen City Natural Science Foundation(No.3502Z20227223).
文摘Techniques for predicting the trajectory of vulnerable road users are important to the development of perception systems for autonomous vehicles to avoid accidents.The most effective trajectory prediction methods,such as Social-LSTM,are often used to predict pedestrian trajectories in normal passage scenarios.However,they can produce unsatisfactory prediction results and data redundancy,as well as difficulties in predicting trajectories using pixel-based coordinate systems in collision avoidance systems.There is also a lack of validations using real vehicle-to-pedestrian collisions.To address these issues,some insightful approaches to improve the trajectory prediction scheme of Social-LSTM were proposed,such methods included transforming pedestrian trajectory coordinates and converting image coordinates to world coordinates.The YOLOv5 detection model was introduced to reduce target loss and improve prediction accuracy.The DeepSORT algorithm was employed to reduce the number of target transformations in the tracking model.Image Perspective Transformation(IPT)and Direct Linear Transformation(DLT)theories were combined to transform the coordinates to world coordinates,identifying the collision location where the accident could occur.The performance of the proposed method was validated by training tests using MS COCO(Microsoft Common Objects in Context)and ETH/UCY datasets.The results showed that the target detection accuracy was more than 90%and the prediction loss tends to decrease with increasing training steps,with the final loss value less than 1%.The reliability and effectiveness of the improved method were demonstrated by benchmarking system performance to two video recordings of real pedestrian accidents with different lighting conditions.
基金Supported by Modern Agricultural Industry Technology System in Henan Province(S2015-04-04)Key Scientific and Technological Project in Henan Province(132102110023)
文摘In order to determine the optimal sowing date of ratoon rice in South Henan's rice-growing areas,this paper performs a comparative analysis of rice growth process,seedling quality and yield of first season rice and ratoon rice under different sowing date treatments. The results show that under climatic conditions( 2014),by using dry seedling cultivation in a small plastic shed,the growth of seedling sown on February21 was affected,while the sowing treatments from March 1 to April 11 can breed normal seedlings,and in this period,the maturity period of first season rice was delayed with prolonged sowing date,and ratoon rice yield declined with prolonged sowing date( total production of rice sown on 11 March reaching a peak). Thus,it is considered that the optimal sowing date of ratoon rice in South Henan's rice-growing areas is mid-March.
基金Supported by Coal-Based Key Science and Technology Program of Shanxi Province(FT2014-03)
文摘[Objectives] This study aimed to study the morphological characteristics and molecular phylogeny of a new strain collected from rotten wood of sea buckthorn in Yanbei area of Shanxi Province. [Methods]The specimens were observed with naked eyes. With Melzer,cotton blue and 5% KOH as floating carriers,the slices were prepared,which were observed under a microscope. The ITS sequence of the new strain was compared with those of the 20 kinds of reported fungi to construct molecular phylogenetic tree based on ITS. [Results] The new strain has horseshoe-shaped basidiocarp and pileus shape and has no stipe. Sometimes,it grows procumbently and scrolled backward. The mycelial system is monomitic. The skeletal hyphae showed a negative reaction in the Melzer reagent and cotton blue reagent. The basidiospores are subglobose or spherical and colorless with thick wall. The results of molecular phylogenetic analysis showed that the new strain had a close relationship with Fomitiporia spp. and was clustered into the same branch with them. It formed an independent sub-branch in the phylogenetic tree. [Conclusions] The new strain was identified as a new species of Fomitiporia,named as Fomitiporia yanbeiensis S. Guo & L. Zhou( Gen Bank: KT861405,Fungal name: FN570360).
基金the National Natural Science Foundation of China(Grant Nos.11974048 and 11974049)the Beijing Science Foundation(Grant No.1192011)。
文摘The competition between the RKKY interaction and the Kondo effect leads to a magnetic phase transition,which occurs ubiquitously in heavy fermion materials.However,there are more and more experimental evidences indicating that the valence fluctuation plays an essential role in the Ce-and Y-based compounds.We study an extended periodic Anderson model(EPAM)which includes the onsite Coulomb repulsion Ucf between the localized electrons and conduction electrons.By employing the density matrix embedding theory,we investigate the EPAM in the symmetric case at half filling.By fixing the onsite Coulomb repulsion U of the localized electrons to an intermediate value,the interplay between the RKKY interaction,the Kondo effect and the Coulomb repulsion Ucf brings rich physics.We find three different phases,the antiferromagnetic phase,the charge order phase and paramagnetic phase.When the hybridization strength V between the localized orbital and the conduction orbital is small,the Kondo effect is weak so that the AF phase and the CO phase are present.The phase transition between the two long-range ordered phase is of first order.We also find a coexistence region between the two phases.As V increases,the Kondo effect becomes stronger,and the paramagnetic phase appears between the other two phases.
基金This work described above was financially supported by National Key R＆D Program of China （No. 2017YFD0200703）, and the General Program of Natural Science Foundation of China （grant number 31572204）. The authors would like to thank Hongying Cai from the Department of Chemical Engineering of Tsinghua Univer- sity for his help with SEM observations and Dongwu Chang from the Department of Thermal Energy Engineering of Tsinghua University for assistance with MP measurements.
文摘In this study, controlled-release fertilizers （CRFs） with five different nitrogen release periods were pre- pared by coating large urea particles with polyethylene （PE） membranes under various experimental conditions. The preliminary and differential solubility rates, release periods, and membrane pore sizes of the obtained CRFs were measured using water immersion, scanning electron microscopy, and mercury porosimetry. For all CRF samples, the median pore diameters of the membranes were equal to 4.5-5.3 nm and pores with sizes smaller than 10 nm accounted for 86-96% of the total pore surface area. The obtained pore diameter distributions differed for the five studied types of CRF, having release periods of 1,2, 4, 6, and 8 months. Thus, for the CRFs with a 1-month release period, the maximum pore diameter reached a magnitude of 4000 nm, while this value did not exceed 30 nm for the CRFs with a release period of 8 months. Hence, we have established a relationship between the release period of CRFs and their effective maximum pore sizes.
基金This work is supported by National Natural Science Foundation of China under grants 71531010 and 71831006.
文摘Condition-based maintenance(CBM)detects early signs of failure and dictates when maintenance should be performed based on the actual condition of a system.In this paper,we first review some of the recent research on CBM under various physical structures and signal data.Then,we summarize several kinds of prognostic models that use monitoring information to estimate the reliability of complex systems or products.Monitoring information also facilitates operational decisions in production planning,spare parts management,reliability improvement,and prognostics and health management.Finally,we suggest some research opportunities for the reliability and operations management communities to fill the research gap between these two fields.
基金The authors would like to express their gratitude to the editors and the anonymous reviewers for their encouraging comments and insightful suggestions,which substantially improved the quality of this paper.This work was supported by the National Natural Science Foundation of China under Grant No.71771044.
文摘Facing the threat of market follower encroachment,this paper constructs game theoretical models based on different channel structures and market structures,investigates following manufacturer's encroachment strategy and technology strategies,and discusses the impact of following manufacturer's strategy on quality decisions.The results show that encroachment always improves consumer surplus by slashing prices when leading manufacturer adopts in-house R&D(IRD);otherwise,it results in lower consumer surplus with mild competition if leading manufacturer is at a technological disadvantage.Furthermore,the technology strategies of following manufacturer are related to their R&D capabilities.The superior one is outsourcing R&D(ORD)for the manufacturers when their R&D capability is weak,otherwise,IRD is optimal.In a word,the leading manufacturer always prefers IRD under certain conditions,while the following manufacturer always prefers ORD.In addition,encroachment restrains quality innovative motivation under fixed or quality-sensitive R&D costs,but can improve quality level when consumers have a higher reference dependency for quality;meanwhile,the following manufacturer adopting ORD is always beneficial to quality improvement.
