Manned spacecraft pose challenges in terms of extremely high safety and reliability, and with the growth of system complexity and longer on-orbit operation time, the traditional management mode, such as monitoring the...Manned spacecraft pose challenges in terms of extremely high safety and reliability, and with the growth of system complexity and longer on-orbit operation time, the traditional management mode, such as monitoring the threshold of parameter passively, is difficult to meet the required safety standards. Predictive maintenance, which analyzes the system heath trend and estimates remaining useful life(RUL) to establish maintenance strategies ahead of time before failure occurs, is a new mode to approach maintenance tasks. Here, a predictive maintenance strategy for complex manned spacecraft is proposed based on the remaining useful life estimation technique. Firstly, a health index is established based on an abundance of telemetry data, reflecting the system's current health state. Secondly, we map the health index to the remaining useful life through system degradation modelling, taking into consideration both the system's stochastic deterioration and uncertainty. The maintenance and management strategies are then made based on the calculated distribution of RUL time. Finally, a case study on Chinese space station energy system predictive maintenance is presented.展开更多
A germafluorene-fluorene copolymer was successfully obtained via Suzuki polymerization.The ger-manium containing copolymer has an efficient blue light emission under the ultraviolet irradiation and its single layer EL...A germafluorene-fluorene copolymer was successfully obtained via Suzuki polymerization.The ger-manium containing copolymer has an efficient blue light emission under the ultraviolet irradiation and its single layer EL device showed the highest brightness of 2630 cd/m2 at 7.8 V and the highest effi-ciency of 0.301 lm/W at 6.2 V.The copolymer can also serve as the host material for phosphorescent metal complexes with the maximum brightness of 15600 cd/m2 and the quantum efficiency of 8.5%.The results are quite promising and promise that as its analogs of fluorene and silafluorene,germafluorene is an excellent building block for blue light-emitting polymers and host materials.展开更多
Nitrogen-doped carbon nanotubes (N-CNTs)/polyaniline (PANI) composites are developed as an electrode material for biosensors. The morphology, composition, and optical properties of the resulting products were characte...Nitrogen-doped carbon nanotubes (N-CNTs)/polyaniline (PANI) composites are developed as an electrode material for biosensors. The morphology, composition, and optical properties of the resulting products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible absorption spectra (UV-vis). Furthermore, N-CNTs/PANI composite was immobilized on the surface of a glassy carbon electrode (GCE) and applied to construct a sensor. The obtained N-CNTs/PANI-modified GCE showed one pair of redox peaks and high catalytic activity for the oxidation of dopamine (DA) in a neutral environment. Differential pulse voltam-mograms results illustrate that the fabricated DA biosensor has high anti-interference ability towards ascorbic acid (AA). In addition, the fabricated biosensor showed superior performances with two wide linear ranges from 1 to 80 μM and from 1.5 to 3.5 mM and a low detection limit of 0.01 μM.展开更多
文摘Manned spacecraft pose challenges in terms of extremely high safety and reliability, and with the growth of system complexity and longer on-orbit operation time, the traditional management mode, such as monitoring the threshold of parameter passively, is difficult to meet the required safety standards. Predictive maintenance, which analyzes the system heath trend and estimates remaining useful life(RUL) to establish maintenance strategies ahead of time before failure occurs, is a new mode to approach maintenance tasks. Here, a predictive maintenance strategy for complex manned spacecraft is proposed based on the remaining useful life estimation technique. Firstly, a health index is established based on an abundance of telemetry data, reflecting the system's current health state. Secondly, we map the health index to the remaining useful life through system degradation modelling, taking into consideration both the system's stochastic deterioration and uncertainty. The maintenance and management strategies are then made based on the calculated distribution of RUL time. Finally, a case study on Chinese space station energy system predictive maintenance is presented.
基金Supported by the National Natural Science Foundation of China (Grant Nos.60325412, 90406021,and 50428303)the Scientific Research Foundation of Nanjing University of Posts and Telecommunications (NUPT) (Grant No. NY206073)
文摘A germafluorene-fluorene copolymer was successfully obtained via Suzuki polymerization.The ger-manium containing copolymer has an efficient blue light emission under the ultraviolet irradiation and its single layer EL device showed the highest brightness of 2630 cd/m2 at 7.8 V and the highest effi-ciency of 0.301 lm/W at 6.2 V.The copolymer can also serve as the host material for phosphorescent metal complexes with the maximum brightness of 15600 cd/m2 and the quantum efficiency of 8.5%.The results are quite promising and promise that as its analogs of fluorene and silafluorene,germafluorene is an excellent building block for blue light-emitting polymers and host materials.
基金supported by the National Natural Science Foundation of China (20905038, 20903057, 20974046, 50803027, 20874048 & 20804020)the National Basic Research Program of China (2009CB930600)+1 种基金the Natural Science Foundation of Jiangsu Province (08KJB150011 & 09KJB150007)the Fok Ying-Tong Education Foundation under Grant 111051
文摘Nitrogen-doped carbon nanotubes (N-CNTs)/polyaniline (PANI) composites are developed as an electrode material for biosensors. The morphology, composition, and optical properties of the resulting products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible absorption spectra (UV-vis). Furthermore, N-CNTs/PANI composite was immobilized on the surface of a glassy carbon electrode (GCE) and applied to construct a sensor. The obtained N-CNTs/PANI-modified GCE showed one pair of redox peaks and high catalytic activity for the oxidation of dopamine (DA) in a neutral environment. Differential pulse voltam-mograms results illustrate that the fabricated DA biosensor has high anti-interference ability towards ascorbic acid (AA). In addition, the fabricated biosensor showed superior performances with two wide linear ranges from 1 to 80 μM and from 1.5 to 3.5 mM and a low detection limit of 0.01 μM.
