Stress response of a tension leg platform (TLP) in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically ...Stress response of a tension leg platform (TLP) in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically simulated and also experimentally verified by a strain gage. Environmental loading and the platform's structural strength were analyzed in accordance with industrial standards, utilizing linear wave theory and the finite element method (FEM). The fast Fourier transform technique was used to calculate the stress response amplitude operators (RAO) from the records of measurements. A comparison was performed between the stress RAO of the numerical simulation and that of the actual measurements. The results indicated that the stress RAO of the numerical simulation fitted well with measured data at specified wave headings with different periods.展开更多
Study of electrochemical behavior of chromium (molybdenum, tungsten) and silicon containing melts allowed defining conditions for synthesis of silicides of chromium, molybdenum and tungsten in the form of fine powde...Study of electrochemical behavior of chromium (molybdenum, tungsten) and silicon containing melts allowed defining conditions for synthesis of silicides of chromium, molybdenum and tungsten in the form of fine powders by electrolysis of halide-oxide melts. Sequence of stages of electrosynthesis of silicides of molybdenum and tungsten was found as follows: deposition of more electroposifve metal (molybdenum or tungsten), deposition of the second component (silicon) on the surface of metal deposited previously, and reaction diffusion of silicon into the deep of the metal-salt "pear" with the formation of silicide phases of different compositions up to the higher silicides. In contrast, during the electrodeposition of chromium silicides, one of the components (chromium) is deposited not in elemental form, but in oxide form, and the other (silicon) acts as a reducing agent for this oxide to form binary compounds. Duration of the synthesis first stage (deposition of refractory metal or of its oxide) depends on the refractory metal compound content in the system and on the cathode current density. Synthesis of silicides is possible due to retention of powders of molybdenum (tungsten) or chromium oxide at the cathode without scaling. Optimal values of concentrations ratio, current density, temperature, and duration of electrosynthesis were found. Phase composition of products were obtained, as well as their chemical and thermal stability, were studied.展开更多
Supercapacitors are expected to bridge the gap between conventional electrostatic capacitors and batteries, but have not found significant application in primary energy devices, partly due to some unsolved problems in...Supercapacitors are expected to bridge the gap between conventional electrostatic capacitors and batteries, but have not found significant application in primary energy devices, partly due to some unsolved problems in the elec- trode materials. A wide range of novel materials such as novel carbons have been investigated to increase the energy den- sity of the electrodes and the volumetric merits of the materi- als need to be specifically considered and evaluated, towards the practical application of these novel materials. In obser- vation of the intense research activity to improve the volu- metric performance of carbon electrodes, the density or mass loading is particularly important and shall be further opti- mized, both for commercially applied activated carbons and in novel carbon electrode materials such as graphene. In this review, we presented a brief overview of the recent progress in improving the volumetric performance of carbon-based su- percapacitor electrodes, particularly highlighting the devel- opment of densified electrodes by various technical strategies including the controlled assembly of carbon building blocks, developing carbon based hybrid composites and constructing micro- supercapacitors.展开更多
We investigate solutions to superlinear or sublinear operator equations and obtain some abstract existence results by minimax methods. These results apply to superlinear or sublinear Hamiltonian systems satisfying sev...We investigate solutions to superlinear or sublinear operator equations and obtain some abstract existence results by minimax methods. These results apply to superlinear or sublinear Hamiltonian systems satisfying several boundary value conditions including Sturm-Liouville boundary value conditions and generalized periodic boundary value conditions, and yield some new theorems concerning existence of solutions or nontrivial solutions. In particular, some famous results about periodic solutions to superlinear or sublinear Hamiltonian systems by Rabinowitz or Benci and Rabinowitz are special cases of the theorems.展开更多
The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a...The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a class of promising energy-storage systems for powering next-generation electric vehicles and electronic devices.Here,we reported a facile and controllable synthesis of core-shell Ni_(3)S_(2)@NiWO_(4)nanoarrays to fabricate a freestanding electrode for hybrid SCs.Impressively,the as-prepared freestanding Ni_(3)S_(2)@NiWO_(4)electrode presents an ultrahigh areal capacity of 2032μA h cm^(-2)at 5 mA cm^(-2),and a capacity retention of 63.6%even when the current density increased up to 50 mA cm^(-2).Remarkably,the Ni_(3)S_(2)@NiWO_(4)nanoarraybased hybrid SC delivers a maximum energy density of 1.283 mW h cm^(-2)at 3.128 mW cm^(-2)and a maximum power density of 41.105 mW cm^(-2)at 0.753 mW h cm^(-2).Furthermore,the hybrid SC exhibits a capacity retention of 89.6%even after continuous 10,000 cycles,proving its superior stability.This study provides a facile pathway to rationally design a variety of core-shell metal nanostructures for high-performance energy storage devices.展开更多
基金supported by the Fund of "111 Project" (Grant No.B07019) from the State Administration of Foreign Experts Affairs and the Ministry of Education of China
文摘Stress response of a tension leg platform (TLP) in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically simulated and also experimentally verified by a strain gage. Environmental loading and the platform's structural strength were analyzed in accordance with industrial standards, utilizing linear wave theory and the finite element method (FEM). The fast Fourier transform technique was used to calculate the stress response amplitude operators (RAO) from the records of measurements. A comparison was performed between the stress RAO of the numerical simulation and that of the actual measurements. The results indicated that the stress RAO of the numerical simulation fitted well with measured data at specified wave headings with different periods.
文摘Study of electrochemical behavior of chromium (molybdenum, tungsten) and silicon containing melts allowed defining conditions for synthesis of silicides of chromium, molybdenum and tungsten in the form of fine powders by electrolysis of halide-oxide melts. Sequence of stages of electrosynthesis of silicides of molybdenum and tungsten was found as follows: deposition of more electroposifve metal (molybdenum or tungsten), deposition of the second component (silicon) on the surface of metal deposited previously, and reaction diffusion of silicon into the deep of the metal-salt "pear" with the formation of silicide phases of different compositions up to the higher silicides. In contrast, during the electrodeposition of chromium silicides, one of the components (chromium) is deposited not in elemental form, but in oxide form, and the other (silicon) acts as a reducing agent for this oxide to form binary compounds. Duration of the synthesis first stage (deposition of refractory metal or of its oxide) depends on the refractory metal compound content in the system and on the cathode current density. Synthesis of silicides is possible due to retention of powders of molybdenum (tungsten) or chromium oxide at the cathode without scaling. Optimal values of concentrations ratio, current density, temperature, and duration of electrosynthesis were found. Phase composition of products were obtained, as well as their chemical and thermal stability, were studied.
基金supported by the Chinese Government 1000 Plan Talent Programthe Ministry of Education's Program for New Century Excellent Talents in the University+2 种基金the National Natural Science Foundation of China(51322204)the Fundamental Research Funds for Central Universities(WK2060140014 and WK2060140017)the funding from Hefei National Synchrotron Radiation Lab
文摘Supercapacitors are expected to bridge the gap between conventional electrostatic capacitors and batteries, but have not found significant application in primary energy devices, partly due to some unsolved problems in the elec- trode materials. A wide range of novel materials such as novel carbons have been investigated to increase the energy den- sity of the electrodes and the volumetric merits of the materi- als need to be specifically considered and evaluated, towards the practical application of these novel materials. In obser- vation of the intense research activity to improve the volu- metric performance of carbon electrodes, the density or mass loading is particularly important and shall be further opti- mized, both for commercially applied activated carbons and in novel carbon electrode materials such as graphene. In this review, we presented a brief overview of the recent progress in improving the volumetric performance of carbon-based su- percapacitor electrodes, particularly highlighting the devel- opment of densified electrodes by various technical strategies including the controlled assembly of carbon building blocks, developing carbon based hybrid composites and constructing micro- supercapacitors.
基金supported by National Natural Science Foundation of China(Grant No.11171157)the Jiangsu Planned Projects for Postdoctoral Research Funds
文摘We investigate solutions to superlinear or sublinear operator equations and obtain some abstract existence results by minimax methods. These results apply to superlinear or sublinear Hamiltonian systems satisfying several boundary value conditions including Sturm-Liouville boundary value conditions and generalized periodic boundary value conditions, and yield some new theorems concerning existence of solutions or nontrivial solutions. In particular, some famous results about periodic solutions to superlinear or sublinear Hamiltonian systems by Rabinowitz or Benci and Rabinowitz are special cases of the theorems.
基金the National Natural Science Foundation of China(91963113)。
文摘The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a class of promising energy-storage systems for powering next-generation electric vehicles and electronic devices.Here,we reported a facile and controllable synthesis of core-shell Ni_(3)S_(2)@NiWO_(4)nanoarrays to fabricate a freestanding electrode for hybrid SCs.Impressively,the as-prepared freestanding Ni_(3)S_(2)@NiWO_(4)electrode presents an ultrahigh areal capacity of 2032μA h cm^(-2)at 5 mA cm^(-2),and a capacity retention of 63.6%even when the current density increased up to 50 mA cm^(-2).Remarkably,the Ni_(3)S_(2)@NiWO_(4)nanoarraybased hybrid SC delivers a maximum energy density of 1.283 mW h cm^(-2)at 3.128 mW cm^(-2)and a maximum power density of 41.105 mW cm^(-2)at 0.753 mW h cm^(-2).Furthermore,the hybrid SC exhibits a capacity retention of 89.6%even after continuous 10,000 cycles,proving its superior stability.This study provides a facile pathway to rationally design a variety of core-shell metal nanostructures for high-performance energy storage devices.