Photosynthesis of hydrogen peroxide(H_(2)O_(2))via oxygen reduction reaction(ORR)and water oxidation reaction(WOR)pathways requires controlled formation of radical intermediates.However,achieving precise control over ...Photosynthesis of hydrogen peroxide(H_(2)O_(2))via oxygen reduction reaction(ORR)and water oxidation reaction(WOR)pathways requires controlled formation of radical intermediates.However,achieving precise control over radical formation in metal-free catalysts remains challenging.Herein,we report a fluorinated COF(Kf-F-COF)featuring framework-bound carbonyl groups as intrinsic radical-generating sites for efficient dual-channel H_(2)O_(2)photosynthesis.This design enables the simultaneous activation of O_(2)and H_(2)O through radical-mediated hydrogen atom transfer processes.Mechanistic studies reveal that fluorination enhances the electron affinity of the carbonyl sites,facilitates diradical formation,and lowers the energy barriers of key reaction steps.As a result,Kf-F-COF achieves a high H_(2)O_(2)production rate of 6.42 mmol g^(-1)h^(-1)and long-term stability under natural sunlight and seawater conditions.This work presents a frameworkcentered radical strategy for dual-pathway H_(2)O_(2)photosynthesis and offers mechanistic insights into regulating COF-based photocatalysts.展开更多
It is well known that the Two-step Weighted Least-Squares(TWLS) is a widely used method for source localization and sensor position refinement. For this reason, we propose a unified framework of the TWLS method for jo...It is well known that the Two-step Weighted Least-Squares(TWLS) is a widely used method for source localization and sensor position refinement. For this reason, we propose a unified framework of the TWLS method for joint estimation of multiple disjoint sources and sensor locations in this paper. Unlike some existing works, the presented method is based on more general measurement model, and therefore it can be applied to many different localization scenarios.Besides, it does not have the initialization and local convergence problem. The closed-form expression for the covariance matrix of the proposed TWLS estimator is also derived by exploiting the first-order perturbation analysis. Moreover, the estimation accuracy of the TWLS method is shown analytically to achieve the Cramér-Rao Bound(CRB) before the threshold effect takes place. The theoretical analysis is also performed in a common mathematical framework, rather than aiming at some specific signal metrics. Finally, two numerical experiments are performed to support the theoretical development in this paper.展开更多
针对海洋传感网(Ocean Sensor Networks,OSNs)中采用非协同算法单一循环地对多个水面目标节点依次定位导致的定位效率低、定位精度差等问题,提出一种基于有效集的再优化协同定位(Active Set Method based Re-Estimation Cooperative Loc...针对海洋传感网(Ocean Sensor Networks,OSNs)中采用非协同算法单一循环地对多个水面目标节点依次定位导致的定位效率低、定位精度差等问题,提出一种基于有效集的再优化协同定位(Active Set Method based Re-Estimation Cooperative Localization,ASM-RECL)算法。研究将原定位的非凸非线性问题转化为基于交替非负约束最小二乘(Alternative Nonnegative Constrained Least Squares,ANCLS)的优化问题,利用有效集法(Active Set Method,ASM)通过内外循环寻求优化问题的可行解。但ASM算法易陷入局部最优,为进一步提升解的质量,改进定位精度,基于ASM得出的可行解,应用一阶泰勒级数线性展开再次构造优化方程,最小化定位误差。此外,研究还推导得到基于协同定位的克劳美罗下界(Cooperative Localization-based Cramer-Rao Low Bound,CRLB-CL),以此作为评价标准评估提出的定位算法的有效性。仿真实验表明,在不同的条件下,ASM-RECL的定位精度较高于其他算法。展开更多
基金supported by the National Key R&D Program of China(2022YFA1502902)the National Natural Science Foundation of China(22201209,22271218,22071182,21931007,22301235)+1 种基金the Shaanxi Province Young Talent Support Plan(2023SYJ28)the Start-Up Funding of Tianjin University and Xi’an Jiaotong University。
文摘Photosynthesis of hydrogen peroxide(H_(2)O_(2))via oxygen reduction reaction(ORR)and water oxidation reaction(WOR)pathways requires controlled formation of radical intermediates.However,achieving precise control over radical formation in metal-free catalysts remains challenging.Herein,we report a fluorinated COF(Kf-F-COF)featuring framework-bound carbonyl groups as intrinsic radical-generating sites for efficient dual-channel H_(2)O_(2)photosynthesis.This design enables the simultaneous activation of O_(2)and H_(2)O through radical-mediated hydrogen atom transfer processes.Mechanistic studies reveal that fluorination enhances the electron affinity of the carbonyl sites,facilitates diradical formation,and lowers the energy barriers of key reaction steps.As a result,Kf-F-COF achieves a high H_(2)O_(2)production rate of 6.42 mmol g^(-1)h^(-1)and long-term stability under natural sunlight and seawater conditions.This work presents a frameworkcentered radical strategy for dual-pathway H_(2)O_(2)photosynthesis and offers mechanistic insights into regulating COF-based photocatalysts.
基金co-supported by the National Natural Science Foundation of China (Nos. 61201381, 61401513 and 61772548)the China Postdoctoral Science Foundation (No. 2016M592989)+1 种基金the Self-Topic Foundation of Information Engineering University, China (No. 2016600701)the Outstanding Youth Foundation of Information Engineering University, China (No. 2016603201)
文摘It is well known that the Two-step Weighted Least-Squares(TWLS) is a widely used method for source localization and sensor position refinement. For this reason, we propose a unified framework of the TWLS method for joint estimation of multiple disjoint sources and sensor locations in this paper. Unlike some existing works, the presented method is based on more general measurement model, and therefore it can be applied to many different localization scenarios.Besides, it does not have the initialization and local convergence problem. The closed-form expression for the covariance matrix of the proposed TWLS estimator is also derived by exploiting the first-order perturbation analysis. Moreover, the estimation accuracy of the TWLS method is shown analytically to achieve the Cramér-Rao Bound(CRB) before the threshold effect takes place. The theoretical analysis is also performed in a common mathematical framework, rather than aiming at some specific signal metrics. Finally, two numerical experiments are performed to support the theoretical development in this paper.
文摘针对海洋传感网(Ocean Sensor Networks,OSNs)中采用非协同算法单一循环地对多个水面目标节点依次定位导致的定位效率低、定位精度差等问题,提出一种基于有效集的再优化协同定位(Active Set Method based Re-Estimation Cooperative Localization,ASM-RECL)算法。研究将原定位的非凸非线性问题转化为基于交替非负约束最小二乘(Alternative Nonnegative Constrained Least Squares,ANCLS)的优化问题,利用有效集法(Active Set Method,ASM)通过内外循环寻求优化问题的可行解。但ASM算法易陷入局部最优,为进一步提升解的质量,改进定位精度,基于ASM得出的可行解,应用一阶泰勒级数线性展开再次构造优化方程,最小化定位误差。此外,研究还推导得到基于协同定位的克劳美罗下界(Cooperative Localization-based Cramer-Rao Low Bound,CRLB-CL),以此作为评价标准评估提出的定位算法的有效性。仿真实验表明,在不同的条件下,ASM-RECL的定位精度较高于其他算法。
