Ordered hierarchical architectures are attractive candidates for electrochemical energy storage applications.Herein,a facile self-template strategy is applied to prepare Fe7Se8 architectures with a monolithic structur...Ordered hierarchical architectures are attractive candidates for electrochemical energy storage applications.Herein,a facile self-template strategy is applied to prepare Fe7Se8 architectures with a monolithic structure via a self-synthesized single precursor and subsequent calcination at high temperature.With the support of oleylamine,the precursor is structurally targeted to engineer the Fe7Se8 microstructure,featuring nanorod bundles arranged along the longitudinal direction.Because of their ordered hierarchical structure,the Fe7Se8 nanorod bundles deliver a high reversible capacity of 300 m Ah g^-1 at 0.5 A g^-1,along with exceptional rate capability up to 20 A g^-1 and long-term cycle life over 8000 cycles,which represents the highest stability of Fe7Se8 anodes for sodium-ion batteries reported to date.The feasibility of the present strategy to prepare metal selenide structures highlights its promising potential for the rational and effective engineering of electrode materials responsible for the electrochemical performance of energy storage systems.展开更多
To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release...To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment,which increased their warpage.TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature.The warpage of Type E increased by 155.88%and 66.67%in the width and diagonal directions,respectively,when the temperature increased from 25C to 100C.The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability.We revealed that the deformation of the TBLCs could be regulated under the synergistic effect of water and temperature.These results provide a scientific basis for improving the uniformity of bamboo bundle composite materials and for developing thin bamboo bundle fiber composite materials with designable structures and controllable performance.展开更多
In this paper, symmetric structure of induction motor system in stationary αβ 0 coordinates is studied by the geometric approach. The results show that the system possesses symmetry ( G,θ,Φ ) and infinitesimal sym...In this paper, symmetric structure of induction motor system in stationary αβ 0 coordinates is studied by the geometric approach. The results show that the system possesses symmetry ( G,θ,Φ ) and infinitesimal symmetry. Under certain conditions, the system can be transformed into a form possessing state space symmetry ( G,Φ ) and infinitesimal state space symmetry by means of state feedback and input coordinate base transform. The results can be extended to the fifth order induction motor system fed by hysteresis band current controlled PWM inverter.展开更多
Let （M, g） be an n-dimensional Riemannian manifold and T＊M be its cotan-gent bundle equipped with the rescaled Sasaki type metric. In this paper, we firstly study the paraholomorphy property of the rescaled Sasaki ...Let （M, g） be an n-dimensional Riemannian manifold and T＊M be its cotan-gent bundle equipped with the rescaled Sasaki type metric. In this paper, we firstly study the paraholomorphy property of the rescaled Sasaki type metric by using some compati-ble paracomplex structures on T＊M. Second, we construct locally decomposable Golden Riemannian structures on T＊M . Finally we investigate curvature properties of T＊M .展开更多
In this paper, an efficient multi-conductor simplification technique is proposed to model the electromagnetic immunity on cable bundles within a braid shielding structure over a large frequency range. By grouping toge...In this paper, an efficient multi-conductor simplification technique is proposed to model the electromagnetic immunity on cable bundles within a braid shielding structure over a large frequency range. By grouping together the conductors based on the knowledge of Z-Smith chart, the required computation time is markedly reduced and the complexity of modeling the completely shielding cable bundles is significantly simplified with a good accuracy. After a brief description of the immunity problems in shielding structure, a six-phase procedure is detailed to generate the geometrical characteristics of the reduced cable bundles. Numerical simulation is carried out by using a commercial software CST to validate the efficiency and advantages of the proposed approach. The research addressed in this paper is considered as a simplified modeling technique for the electromagnetic immunity within a shielding structure.展开更多
In this paper,we first solve the Dirichlet problem forα-Hermite-Yang-Mills-Higgs equations on I_(±)-Higgs bundles over a compact generalized Kahler manifold.Then we prove that theα-semi-stability on I_(±)-...In this paper,we first solve the Dirichlet problem forα-Hermite-Yang-Mills-Higgs equations on I_(±)-Higgs bundles over a compact generalized Kahler manifold.Then we prove that theα-semi-stability on I_(±)-Higgs bundles over closed generalized Kahler manifolds implies the existence of approximateα-Hermite-Yang-Mills-Higgs structure.展开更多
Let(M,J,g)be an anti-Kähler manifold of dimension n=2k with an almost complex structure J and a pseudo-Riemannian metric g and let T*M be its cotangent bundle with modifiedRiemannian extension metric g■,G.The mo...Let(M,J,g)be an anti-Kähler manifold of dimension n=2k with an almost complex structure J and a pseudo-Riemannian metric g and let T*M be its cotangent bundle with modifiedRiemannian extension metric g■,G.The modified Riemannian extension metric g,g is obtained by deformation in the horizontal part of the Riemannian extension known in the literature by means of the twin Norden metric G.The paper aims first to examine the curvature properties of the cotangent bundle T*M with modified Riemannian extension metric g,G and second to study some geometric solitons on the cotangent bundle T*M according to the modifiedRiemannian extension metric g■,G.展开更多
Rising global change intensifies water scarcity in China’s vital Yellow River Basin grain region,which mounts the need for precise spatial water management.In this study,we investigated the irrigation water demand fo...Rising global change intensifies water scarcity in China’s vital Yellow River Basin grain region,which mounts the need for precise spatial water management.In this study,we investigated the irrigation water demand for seven major crops in cities at the prefecture level between 2000 and 2019.Using Logarithmic Mean Divisia Index(LMDI)decomposition and k-means clustering,we quantified how yield,area,water use efficiency,and cropping patterns affect water demand and identified five irrigation development clusters.Key water-saving areas were identified by tracking transitions among clusters,and NSGA-II was applied to optimize crop structure.The results revealed that the total irrigation demand in the Yellow River Basin averaged 50.09 billion m3/year,with wheat accounting for 54.7%.The increase in yield and area increased demand by 15.2 and 5.5 billion m3,respectively,which was partly offset by changes in water use efficiency and cropping pattern(−7.0 and−1.8 billion m^(3),respectively).Regions in the upper reaches,particularly within the Lanzhou-Toudaoguai section,were identified as critical for water conservation.Optimization of the cropping structure in key regions can reduce annual irrigation water demand by 280 million m3,which accounts for 4.9%of the total demand in these areas,with minimal impact on crop production.This study provides a spatially explicit basis for targeted water conservation strategies in water-scarce agricultural regions.展开更多
Epilepsy is a common neurological disorder, and its electrophysiology characteristic is abnormally high excitability and synchronization of the neural activity. This paper focuses on the study of medial temporal lobe ...Epilepsy is a common neurological disorder, and its electrophysiology characteristic is abnormally high excitability and synchronization of the neural activity. This paper focuses on the study of medial temporal lobe epilepsy with hippocampal sclerosis. The hippocampus plays an important role in short-term memory. However, little is known about the connectivity between hippocampal structures and adjacent brain regions. The functional and structural connectivity between patients and controls was investigated by using the techniques of functional magnetic resonance imaging and diffusion tensor imaging in the paper. Three pairs of ROIs related to working memory from BOLD-fMRI data were chosen. These ROIs were registrated from MNI space to individual space and the fiber bundle between two ROIs were traced in the DTI images. The results show that the number of fiber bundle of patients reduce among these ROIs, such as left hippocampus and right hippocampus, left hippocampus and left thalamus, left hippocampus and left frontal lobe and so on. And the number of fiber bundle of patients increase among these ROIs, such as left thalamus and right thalamus, right hippocampus and right thalamus. And the FA values of the fiber bundles of patients in some regions related to left hippocampus decrease. The cause of abnormal functional and structural connections due to the damage of hippocampus in medial temporal lobe epilepsy is studied from a new perspective.展开更多
Pan-tilt-zoom(PTZ)相机能通过绕光心纯旋转以获得更大视场,被广泛应用于监控系统中。针对在处理PTZ相机影像定向时现有运动恢复结构(structure from motion,SfM)方法存在适用性不足的问题,参考全局式SfM的思路,提出一种面向PTZ相机纯...Pan-tilt-zoom(PTZ)相机能通过绕光心纯旋转以获得更大视场,被广泛应用于监控系统中。针对在处理PTZ相机影像定向时现有运动恢复结构(structure from motion,SfM)方法存在适用性不足的问题,参考全局式SfM的思路,提出一种面向PTZ相机纯旋转运动的影像定向方法。首先,优选部分像对进行内定向,估计影像的内方位元素;然后,对所有影像进行全局式外定向,估计影像的外方位角元素;最后,利用无物方点的光束法平差优化内方位元素和外方位角元素。仿真数据和真实数据的实验表明,该方法可弥补现有SfM方法的不足,成功实现对PTZ相机纯旋转时的影像定向;在与商用软件对比方面,得到的外定向精度更高,同时具有计算效率上的优势。该方法并不局限于PTZ相机影像的定向,对于多镜头相机、全向相机等设备采集的纯旋转影像的定向问题具有通用性。展开更多
Utilization of carbon-based materials is crucial for mitigating CO_(2) emissions.However,practical materials for CO_(2) capture remain challenging due to limitations in adsorption capacity and rate.Inspired by the uni...Utilization of carbon-based materials is crucial for mitigating CO_(2) emissions.However,practical materials for CO_(2) capture remain challenging due to limitations in adsorption capacity and rate.Inspired by the unique structural features of biomass materials,high-performance hierarchical porous carbon was prepared using vascular plants.The ordered arrangement structure effectively improved the adsorption capacity and rate of the material by optimizing the pore structure.Potassium hydroxide(KOH)was used as an activator to synthesize microporous carbon with an ordered hierarchical structure.The properties of hierarchical porous carbon were characterized.The experimental results indicate that porous carbon prepared from loofah complex has excellent CO_(2) adsorption capacity.The highest adsorption capacity is 4.09 mmol/g when the activation temperature is 700℃.The selectivity(15/85)for the binary gas mixture CO_(2)/N_(2) was 20,and the recoverability was good after 10 cycles.The hierarchical porous carbon derived from loofah showed excellent adsorption performance and has potential in various applications.展开更多
基金the National Natural Science Foundation of China(21871164)the Natural Science Foundation of Shandong Province(ZR2019MB024)the Taishan Scholar Project of Shandong Province(no.ts201511004).
文摘Ordered hierarchical architectures are attractive candidates for electrochemical energy storage applications.Herein,a facile self-template strategy is applied to prepare Fe7Se8 architectures with a monolithic structure via a self-synthesized single precursor and subsequent calcination at high temperature.With the support of oleylamine,the precursor is structurally targeted to engineer the Fe7Se8 microstructure,featuring nanorod bundles arranged along the longitudinal direction.Because of their ordered hierarchical structure,the Fe7Se8 nanorod bundles deliver a high reversible capacity of 300 m Ah g^-1 at 0.5 A g^-1,along with exceptional rate capability up to 20 A g^-1 and long-term cycle life over 8000 cycles,which represents the highest stability of Fe7Se8 anodes for sodium-ion batteries reported to date.The feasibility of the present strategy to prepare metal selenide structures highlights its promising potential for the rational and effective engineering of electrode materials responsible for the electrochemical performance of energy storage systems.
基金supported by the Youth Top-notch Talent Program of Science and Technology Innovation for Forestry and Grassland(2019132606).
文摘To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment,which increased their warpage.TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature.The warpage of Type E increased by 155.88%and 66.67%in the width and diagonal directions,respectively,when the temperature increased from 25C to 100C.The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability.We revealed that the deformation of the TBLCs could be regulated under the synergistic effect of water and temperature.These results provide a scientific basis for improving the uniformity of bamboo bundle composite materials and for developing thin bamboo bundle fiber composite materials with designable structures and controllable performance.
文摘In this paper, symmetric structure of induction motor system in stationary αβ 0 coordinates is studied by the geometric approach. The results show that the system possesses symmetry ( G,θ,Φ ) and infinitesimal symmetry. Under certain conditions, the system can be transformed into a form possessing state space symmetry ( G,Φ ) and infinitesimal state space symmetry by means of state feedback and input coordinate base transform. The results can be extended to the fifth order induction motor system fed by hysteresis band current controlled PWM inverter.
文摘Let （M, g） be an n-dimensional Riemannian manifold and T＊M be its cotan-gent bundle equipped with the rescaled Sasaki type metric. In this paper, we firstly study the paraholomorphy property of the rescaled Sasaki type metric by using some compati-ble paracomplex structures on T＊M. Second, we construct locally decomposable Golden Riemannian structures on T＊M . Finally we investigate curvature properties of T＊M .
基金Project supported by the National Natural Science Foundation of China(Grant No.51675086)the National Defense Pre-Research Foundation of China(Grant No.6140758010116DZ02002)
文摘In this paper, an efficient multi-conductor simplification technique is proposed to model the electromagnetic immunity on cable bundles within a braid shielding structure over a large frequency range. By grouping together the conductors based on the knowledge of Z-Smith chart, the required computation time is markedly reduced and the complexity of modeling the completely shielding cable bundles is significantly simplified with a good accuracy. After a brief description of the immunity problems in shielding structure, a six-phase procedure is detailed to generate the geometrical characteristics of the reduced cable bundles. Numerical simulation is carried out by using a commercial software CST to validate the efficiency and advantages of the proposed approach. The research addressed in this paper is considered as a simplified modeling technique for the electromagnetic immunity within a shielding structure.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11971253,11625106,11801535,11721101)the Natural Science Foundation of Anhui Province(Grant No.1908085QA04)Partially Supported by the Project“Analysis and Geometry on Bundle”of Ministry of Science and Technology of the People’s Republic of China(Grant No.SQ2020YFA070080)。
文摘In this paper,we first solve the Dirichlet problem forα-Hermite-Yang-Mills-Higgs equations on I_(±)-Higgs bundles over a compact generalized Kahler manifold.Then we prove that theα-semi-stability on I_(±)-Higgs bundles over closed generalized Kahler manifolds implies the existence of approximateα-Hermite-Yang-Mills-Higgs structure.
文摘Let(M,J,g)be an anti-Kähler manifold of dimension n=2k with an almost complex structure J and a pseudo-Riemannian metric g and let T*M be its cotangent bundle with modifiedRiemannian extension metric g■,G.The modified Riemannian extension metric g,g is obtained by deformation in the horizontal part of the Riemannian extension known in the literature by means of the twin Norden metric G.The paper aims first to examine the curvature properties of the cotangent bundle T*M with modified Riemannian extension metric g,G and second to study some geometric solitons on the cotangent bundle T*M according to the modifiedRiemannian extension metric g■,G.
基金National Natural Science Foundation of China,No.42041007。
文摘Rising global change intensifies water scarcity in China’s vital Yellow River Basin grain region,which mounts the need for precise spatial water management.In this study,we investigated the irrigation water demand for seven major crops in cities at the prefecture level between 2000 and 2019.Using Logarithmic Mean Divisia Index(LMDI)decomposition and k-means clustering,we quantified how yield,area,water use efficiency,and cropping patterns affect water demand and identified five irrigation development clusters.Key water-saving areas were identified by tracking transitions among clusters,and NSGA-II was applied to optimize crop structure.The results revealed that the total irrigation demand in the Yellow River Basin averaged 50.09 billion m3/year,with wheat accounting for 54.7%.The increase in yield and area increased demand by 15.2 and 5.5 billion m3,respectively,which was partly offset by changes in water use efficiency and cropping pattern(−7.0 and−1.8 billion m^(3),respectively).Regions in the upper reaches,particularly within the Lanzhou-Toudaoguai section,were identified as critical for water conservation.Optimization of the cropping structure in key regions can reduce annual irrigation water demand by 280 million m3,which accounts for 4.9%of the total demand in these areas,with minimal impact on crop production.This study provides a spatially explicit basis for targeted water conservation strategies in water-scarce agricultural regions.
基金National Natural Science Foundation of Chinagrant number: 6075107
文摘Epilepsy is a common neurological disorder, and its electrophysiology characteristic is abnormally high excitability and synchronization of the neural activity. This paper focuses on the study of medial temporal lobe epilepsy with hippocampal sclerosis. The hippocampus plays an important role in short-term memory. However, little is known about the connectivity between hippocampal structures and adjacent brain regions. The functional and structural connectivity between patients and controls was investigated by using the techniques of functional magnetic resonance imaging and diffusion tensor imaging in the paper. Three pairs of ROIs related to working memory from BOLD-fMRI data were chosen. These ROIs were registrated from MNI space to individual space and the fiber bundle between two ROIs were traced in the DTI images. The results show that the number of fiber bundle of patients reduce among these ROIs, such as left hippocampus and right hippocampus, left hippocampus and left thalamus, left hippocampus and left frontal lobe and so on. And the number of fiber bundle of patients increase among these ROIs, such as left thalamus and right thalamus, right hippocampus and right thalamus. And the FA values of the fiber bundles of patients in some regions related to left hippocampus decrease. The cause of abnormal functional and structural connections due to the damage of hippocampus in medial temporal lobe epilepsy is studied from a new perspective.
文摘Pan-tilt-zoom(PTZ)相机能通过绕光心纯旋转以获得更大视场,被广泛应用于监控系统中。针对在处理PTZ相机影像定向时现有运动恢复结构(structure from motion,SfM)方法存在适用性不足的问题,参考全局式SfM的思路,提出一种面向PTZ相机纯旋转运动的影像定向方法。首先,优选部分像对进行内定向,估计影像的内方位元素;然后,对所有影像进行全局式外定向,估计影像的外方位角元素;最后,利用无物方点的光束法平差优化内方位元素和外方位角元素。仿真数据和真实数据的实验表明,该方法可弥补现有SfM方法的不足,成功实现对PTZ相机纯旋转时的影像定向;在与商用软件对比方面,得到的外定向精度更高,同时具有计算效率上的优势。该方法并不局限于PTZ相机影像的定向,对于多镜头相机、全向相机等设备采集的纯旋转影像的定向问题具有通用性。
文摘Utilization of carbon-based materials is crucial for mitigating CO_(2) emissions.However,practical materials for CO_(2) capture remain challenging due to limitations in adsorption capacity and rate.Inspired by the unique structural features of biomass materials,high-performance hierarchical porous carbon was prepared using vascular plants.The ordered arrangement structure effectively improved the adsorption capacity and rate of the material by optimizing the pore structure.Potassium hydroxide(KOH)was used as an activator to synthesize microporous carbon with an ordered hierarchical structure.The properties of hierarchical porous carbon were characterized.The experimental results indicate that porous carbon prepared from loofah complex has excellent CO_(2) adsorption capacity.The highest adsorption capacity is 4.09 mmol/g when the activation temperature is 700℃.The selectivity(15/85)for the binary gas mixture CO_(2)/N_(2) was 20,and the recoverability was good after 10 cycles.The hierarchical porous carbon derived from loofah showed excellent adsorption performance and has potential in various applications.
