Cobalt‐based materials have been considered as promising candidates to electrocatalyze water oxidation.However,the structure‐performance correlation remains largely elusive,due to the com‐plex material structures a...Cobalt‐based materials have been considered as promising candidates to electrocatalyze water oxidation.However,the structure‐performance correlation remains largely elusive,due to the com‐plex material structures and diverse performance‐influencing factors in those Co‐based catalysts.In this work,we designed two cobalt phosphates with distinct Co symmetry to explore the effect of coordination symmetry on electrocatalytic water oxidation.The two analogues have similar mor‐phology,Co valence and 6‐coordinated Co octahedron,but with different coordination symmetry.In contrast to symmetric Co_(3)(PO_(4))2·8H_(2)O,asymmetric NH_(4)CoPO_(4)·H_(2)O exhibited enhanced electrocata‐lytic water oxidation activity in a neutral aqueous solution.It is proven that,by experimental and theoretical studies,the asymmetric Co coordination sites can facilitate the surface reconstruction under anodic polarization to boost the electrocatalysis.Based on this contrastive platform with distinct symmetry differences,the preferred configuration in cobalt‐oxygen octahedrons for water oxidation has been straightforwardly assigned.展开更多
The purpose of this article is to present an additional overloading assessment scheme to the current protection scheme, which can be applied in the low voltage distribution network to prevent overloading of network as...The purpose of this article is to present an additional overloading assessment scheme to the current protection scheme, which can be applied in the low voltage distribution network to prevent overloading of network assets. As higher penetration of distributed generators is envisioned among distribution networks, the network operators will have an challenging task in the future to maintain the reliability and quality of supply. The distribution networks are going to be challenged simultaneously by increasing penetration of distributed generators and by increasing loading (inter alia heat pumps, air conditioners or electric vehicles), which will change the operational perspective of the future distribution networks. Presented simulation results show that the increasing penetration of those appliances can jeopardize the functionality of current protection scheme in distribution networks. Therefore, an additional scheme for assessment of network overloading applicable at low voltage distribution networks is proposed and the application of this scheme, supported by smart metering infrastructure, is demonstrated in a case study. The proposed overloading assessment scheme should help the network operators to increase the flexibility of distribution networks, their hosting capacity, safety and reliability.展开更多
This work includes synthesis of 2,2'-(5,5'-(ethane-1,2-diyl)bis(1,3,4-oxadiazole-5,2diyl))bis(sulfanediyl)dibenzenamine (EOSBE) and 2,2'-(5,5'-methylenebis(1,3,4-oxadiazole-5,2-diyl)bis(sulfanediyl)...This work includes synthesis of 2,2'-(5,5'-(ethane-1,2-diyl)bis(1,3,4-oxadiazole-5,2diyl))bis(sulfanediyl)dibenzenamine (EOSBE) and 2,2'-(5,5'-methylenebis(1,3,4-oxadiazole-5,2-diyl)bis(sulfanediyl))dibenzenamine (MOSBE). All synthesized ligands were characterized by IR, ^1H-NMR, ^13C-NMR, UV-visible spectroscopies and molar conductivity. A series of complexes with a general formula [M2LCl4]. Where M(Ⅱ) = Co, Ni, Cu and Zn; L = EOSBE and MOSBE were synthesized in basic media using KOH solution. In these complexes both ligands are bidentate ligands coordinated through sulfur and nitrogen. All complexes have been characterized by IR-spectra, UV-visiblc spectra, conductivity and magnetic susceptibility.展开更多
This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with ti...This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods. The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative error 0.02% - 0.04% ) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for piezoelectric structural analysis due to the assumptions and corrections in the plate theories.The converged lagrange finite element methods are compared with the plate element methods and the computedresults are in good agreement with available exact and experimental data. The adaptive Lagrange finite elementmethods and a new FEA computer program developed for macro- and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.展开更多
Objective To observe the influence of different acupoint combinations on immediate effect of surface electromyography of patients with cervical spondylosis, and to explore the interactions and laws among different acu...Objective To observe the influence of different acupoint combinations on immediate effect of surface electromyography of patients with cervical spondylosis, and to explore the interactions and laws among different acupoint combinations. Methods Acupuncture in three kinds of different acupoint combinations was conducted on 90 patients with cervical spondylosis(three groups): group A [distal point selection group: Kūnlún(昆仑 BL 60) and Hòuxī(后溪 SI 3)]; group B [local point selection group: Fēngchí(风池 GB 20) and Tiānzhù(天柱 BL 10)]; group C(distal and local point selection group: BL 60, SI 3, GB 20 and BL 10). Self control before and after treatment was adopted to observe the mean value of surface electromyography(SEMG) amplitude, to measure the mean values of integrated electromyography(IEMG) and electromyography root mean square(RMS), and to calculate the variation rate of electromyography amplitude of trapezius on the affected side of patients before and after acupuncture. The differences of influences of different acupoint combinations on immediate effect of surface electromyography were compared intra-group, and the differences among the three groups after acupuncture were also compared. Results According to the intragroup comparison before and after acupuncture, the differences of mean value of electromyography amplitude, variation rate of electromyography amplitude, IEMG and RMS were both statistically significant(all P〈0.05). According to the inter-group comparison after acupuncture, the mean value of electromyography amplitude, variation rate of electromyography amplitude, IEMG and RMS varied in different degrees, however, the differences were not significant(all P〉0.05); there was no significant difference in the total effective rate among the three groups(P〉0.05). Conclusion Acupuncture treatment in different acupoint combinations can increase IEMG and RMS and reduce mean value of electromyography amplitude and variation rate of electromyography amplitude, enhance cervical vertebral stability and active contractility of muscle fiber, and improve the fatigue resistance of neck flexion; while, the therapeutic effect of acupuncture on cervical spondylosis has nothing to do with the distance or the number of selected acupoint.展开更多
A thermodynamic model of a thermoelectric generator(TEG)-driven thermoelectric cooler(TEC) device considering Thomson effect and external heat transfer(HT) is established based on the combination of non-equilibrium an...A thermodynamic model of a thermoelectric generator(TEG)-driven thermoelectric cooler(TEC) device considering Thomson effect and external heat transfer(HT) is established based on the combination of non-equilibrium and finite time thermodynamic theories. The expressions of cooling capacity and coefficient of performance(COP) are obtained. Performances are compared with and without considering Thomson effect using numerical optimization method. The influences of Thomson effect on the optimal performances, optimum allocations of thermoelectric(TE) element number and HT surface area are discussed. The results indicate that Thomson effect decreases the maximum cooling capacity and COP. More TE elements should be allocated to TEG, and more HT area should be allocated to the heat exchanger(HEX) of TEG, the hot-side HEX of TEG and the cold-side HEX of TEC in the design of the device considering Thomson effect. The results obtained can be used to help design TEG-TEC devices.展开更多
Heteroatom-doped Pt-based nanocrystals have generated considerable interest and hold great prospects in heterocatalysis. However, engineering the superficial atomic configurations of these nanocrystals via in situ sur...Heteroatom-doped Pt-based nanocrystals have generated considerable interest and hold great prospects in heterocatalysis. However, engineering the superficial atomic configurations of these nanocrystals via in situ surface doping remains exceedingly challenging. Herein, we propose a onepot, in situ surface doping chemical synthesis protocol to prepare quatermetallic Pt Ni Co Rh dendritic nanocrystals as versatile and active catalysts for the electrooxidation of C_(1) fuels. Leveraging the selective coordination effect between ascorbic acid and Rh^(3+)ions, the doping of trace Rh atoms can be guided specifically at the near-surface of Pt Ni Co Rh nanocatalysts. Electrocatalytic tests indicate that Pt_(67)Ni_(16)Co_(16)Rh_(1) nanocrystals with in situ trace Rh-doped surface exhibit substantially enhanced activity, durability, and CO tolerance for the electrooxidation of methanol, formaldehyde, and formic acid. In situ Fourier transform infrared spectroscopy provides molecular-level insight into the exceptional performance of these nanocatalysts. The surface incorporation of anticorrosive Rh atoms enables the transfer of CO intermediates from the atop Pt sites to the bridged Rh–Pt surface sites,thereby facilitating the elimination of these poisoning species from the catalyst surface. This study presents an effective in situ surface doping strategy which can enable the design of more atom-economic heterocatalysts.展开更多
文摘Cobalt‐based materials have been considered as promising candidates to electrocatalyze water oxidation.However,the structure‐performance correlation remains largely elusive,due to the com‐plex material structures and diverse performance‐influencing factors in those Co‐based catalysts.In this work,we designed two cobalt phosphates with distinct Co symmetry to explore the effect of coordination symmetry on electrocatalytic water oxidation.The two analogues have similar mor‐phology,Co valence and 6‐coordinated Co octahedron,but with different coordination symmetry.In contrast to symmetric Co_(3)(PO_(4))2·8H_(2)O,asymmetric NH_(4)CoPO_(4)·H_(2)O exhibited enhanced electrocata‐lytic water oxidation activity in a neutral aqueous solution.It is proven that,by experimental and theoretical studies,the asymmetric Co coordination sites can facilitate the surface reconstruction under anodic polarization to boost the electrocatalysis.Based on this contrastive platform with distinct symmetry differences,the preferred configuration in cobalt‐oxygen octahedrons for water oxidation has been straightforwardly assigned.
文摘The purpose of this article is to present an additional overloading assessment scheme to the current protection scheme, which can be applied in the low voltage distribution network to prevent overloading of network assets. As higher penetration of distributed generators is envisioned among distribution networks, the network operators will have an challenging task in the future to maintain the reliability and quality of supply. The distribution networks are going to be challenged simultaneously by increasing penetration of distributed generators and by increasing loading (inter alia heat pumps, air conditioners or electric vehicles), which will change the operational perspective of the future distribution networks. Presented simulation results show that the increasing penetration of those appliances can jeopardize the functionality of current protection scheme in distribution networks. Therefore, an additional scheme for assessment of network overloading applicable at low voltage distribution networks is proposed and the application of this scheme, supported by smart metering infrastructure, is demonstrated in a case study. The proposed overloading assessment scheme should help the network operators to increase the flexibility of distribution networks, their hosting capacity, safety and reliability.
文摘This work includes synthesis of 2,2'-(5,5'-(ethane-1,2-diyl)bis(1,3,4-oxadiazole-5,2diyl))bis(sulfanediyl)dibenzenamine (EOSBE) and 2,2'-(5,5'-methylenebis(1,3,4-oxadiazole-5,2-diyl)bis(sulfanediyl))dibenzenamine (MOSBE). All synthesized ligands were characterized by IR, ^1H-NMR, ^13C-NMR, UV-visible spectroscopies and molar conductivity. A series of complexes with a general formula [M2LCl4]. Where M(Ⅱ) = Co, Ni, Cu and Zn; L = EOSBE and MOSBE were synthesized in basic media using KOH solution. In these complexes both ligands are bidentate ligands coordinated through sulfur and nitrogen. All complexes have been characterized by IR-spectra, UV-visiblc spectra, conductivity and magnetic susceptibility.
文摘This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods. The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative error 0.02% - 0.04% ) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for piezoelectric structural analysis due to the assumptions and corrections in the plate theories.The converged lagrange finite element methods are compared with the plate element methods and the computedresults are in good agreement with available exact and experimental data. The adaptive Lagrange finite elementmethods and a new FEA computer program developed for macro- and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.
基金Supported by “The 12th five-year plan” programmed project of educational science in Hubei Province:2014B095
文摘Objective To observe the influence of different acupoint combinations on immediate effect of surface electromyography of patients with cervical spondylosis, and to explore the interactions and laws among different acupoint combinations. Methods Acupuncture in three kinds of different acupoint combinations was conducted on 90 patients with cervical spondylosis(three groups): group A [distal point selection group: Kūnlún(昆仑 BL 60) and Hòuxī(后溪 SI 3)]; group B [local point selection group: Fēngchí(风池 GB 20) and Tiānzhù(天柱 BL 10)]; group C(distal and local point selection group: BL 60, SI 3, GB 20 and BL 10). Self control before and after treatment was adopted to observe the mean value of surface electromyography(SEMG) amplitude, to measure the mean values of integrated electromyography(IEMG) and electromyography root mean square(RMS), and to calculate the variation rate of electromyography amplitude of trapezius on the affected side of patients before and after acupuncture. The differences of influences of different acupoint combinations on immediate effect of surface electromyography were compared intra-group, and the differences among the three groups after acupuncture were also compared. Results According to the intragroup comparison before and after acupuncture, the differences of mean value of electromyography amplitude, variation rate of electromyography amplitude, IEMG and RMS were both statistically significant(all P〈0.05). According to the inter-group comparison after acupuncture, the mean value of electromyography amplitude, variation rate of electromyography amplitude, IEMG and RMS varied in different degrees, however, the differences were not significant(all P〉0.05); there was no significant difference in the total effective rate among the three groups(P〉0.05). Conclusion Acupuncture treatment in different acupoint combinations can increase IEMG and RMS and reduce mean value of electromyography amplitude and variation rate of electromyography amplitude, enhance cervical vertebral stability and active contractility of muscle fiber, and improve the fatigue resistance of neck flexion; while, the therapeutic effect of acupuncture on cervical spondylosis has nothing to do with the distance or the number of selected acupoint.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51576207, and 11305266)the Natural Science Foundation of Naval University of Engineering (Greant No. 20161505)
文摘A thermodynamic model of a thermoelectric generator(TEG)-driven thermoelectric cooler(TEC) device considering Thomson effect and external heat transfer(HT) is established based on the combination of non-equilibrium and finite time thermodynamic theories. The expressions of cooling capacity and coefficient of performance(COP) are obtained. Performances are compared with and without considering Thomson effect using numerical optimization method. The influences of Thomson effect on the optimal performances, optimum allocations of thermoelectric(TE) element number and HT surface area are discussed. The results indicate that Thomson effect decreases the maximum cooling capacity and COP. More TE elements should be allocated to TEG, and more HT area should be allocated to the heat exchanger(HEX) of TEG, the hot-side HEX of TEG and the cold-side HEX of TEC in the design of the device considering Thomson effect. The results obtained can be used to help design TEG-TEC devices.
基金supported by the National Natural Science Foundation of China (21771067)the Natural Science Foundation of Fujian Province (2017J06005 and 2019J01058)+3 种基金the Program for New Century Excellent Talents in Fujian Province Universitythe Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University (ZQN-PY507)the Scientific Research Funds of Huaqiao Universitythe Instrumental Analysis Center of Huaqiao University for the analysis support。
文摘Heteroatom-doped Pt-based nanocrystals have generated considerable interest and hold great prospects in heterocatalysis. However, engineering the superficial atomic configurations of these nanocrystals via in situ surface doping remains exceedingly challenging. Herein, we propose a onepot, in situ surface doping chemical synthesis protocol to prepare quatermetallic Pt Ni Co Rh dendritic nanocrystals as versatile and active catalysts for the electrooxidation of C_(1) fuels. Leveraging the selective coordination effect between ascorbic acid and Rh^(3+)ions, the doping of trace Rh atoms can be guided specifically at the near-surface of Pt Ni Co Rh nanocatalysts. Electrocatalytic tests indicate that Pt_(67)Ni_(16)Co_(16)Rh_(1) nanocrystals with in situ trace Rh-doped surface exhibit substantially enhanced activity, durability, and CO tolerance for the electrooxidation of methanol, formaldehyde, and formic acid. In situ Fourier transform infrared spectroscopy provides molecular-level insight into the exceptional performance of these nanocatalysts. The surface incorporation of anticorrosive Rh atoms enables the transfer of CO intermediates from the atop Pt sites to the bridged Rh–Pt surface sites,thereby facilitating the elimination of these poisoning species from the catalyst surface. This study presents an effective in situ surface doping strategy which can enable the design of more atom-economic heterocatalysts.