New results of two computer experiments on modeling of superthermal neutron-nuclear combustion of natural uranium for two different flux densities of external neutron source and duration of half a year each are presen...New results of two computer experiments on modeling of superthermal neutron-nuclear combustion of natural uranium for two different flux densities of external neutron source and duration of half a year each are presented. The simulation results demonstrate the dependence of the autowave combustion modes on the parameters of the external source.展开更多
The effect of thermal shock, in an accelerated-corrosion environment spectrum, on the fatigue and corrosion behavior of 7B04-T6 aluminum alloy, was determined. The environment spectrum consists of two modules, namely...The effect of thermal shock, in an accelerated-corrosion environment spectrum, on the fatigue and corrosion behavior of 7B04-T6 aluminum alloy, was determined. The environment spectrum consists of two modules, namely： salt-spray corrosion and thermal shock. The effect of thermal shock on the mechanical properties was determined via tensile tests; SEM, DCS, and XRD were used to determine the effect of thermal shock on the corrosion products. In addition, the corrosion resistance of the products was ascertained through electrochemical testing. The results show that the mechanical properties and fatigue life of the aluminum alloy will decline with prolonged thermal shock time. The thermal shock process may result in denser surface corrosion products than those formed on the no thermal shock specimens, and transformation of some Al（OH）_3 into Al OOH. Al OOH may have resulted in improved corrosion resistance and hence a lower decrease in the fatigue life after corrosion, compared with that of the no thermal shock specimen. Repeated corrosion/thermal shock may have delayed further decease in the fatigue life. Therefore, selection of an appropriate equivalent thermal shock temperature and time was essential for designing the environmental spectrum.展开更多
In this work, a new TeO2-BaO-BaF2-La2O3-LaF3 oxyfluorotellurite glass system is investigated. Differential thermal analysis (DTA) and structural analysis by Raman scattering spectra are reported on the glasses. The DT...In this work, a new TeO2-BaO-BaF2-La2O3-LaF3 oxyfluorotellurite glass system is investigated. Differential thermal analysis (DTA) and structural analysis by Raman scattering spectra are reported on the glasses. The DTA results indicated that an increase of fluoride content in the glasses decreases the glass transition temperature (Tg) and increases the crystallization onset temperature (Tx). As a result the 70TeO2·20BaF2·10LaF3 glass showed a large Hruby's parameter, possessing excellent thermal stability. Changes in glass network structure with fluoride content are discussed based on the Raman scattering spectra of glasses. The glass network structures in the 70TeO2·4(20-x)BaO·xBaF2·(10-y)La2O3·yaF3 glasses are basically composed of both Te(O, F)4 and Te(O, F)3 units, but the Te(O, F)4/Te(O, F)3 ratio in the glass becomes higher with increasing fluoride content. This may be considered one of the reasons why the 70TeO2·20BaF2·10LaF3 glass exhibits excellent thermal stability.展开更多
We present a study of the fabrication of monolayer MoS_2 on n-Si(111) substrates by modified thermal evaporation deposition and the optoelectrical properties of the resulting film. The as-grown MoS_2 ultrathin film is...We present a study of the fabrication of monolayer MoS_2 on n-Si(111) substrates by modified thermal evaporation deposition and the optoelectrical properties of the resulting film. The as-grown MoS_2 ultrathin film is about 10 nm thick, or about a few atomic layers of MoS_2. The film has a large optical absorption range of 300-700 nm and strong luminescence emission at 682 nm. The optical absorption range covered almost the entire ultraviolet to visible light range, which is very useful for making high-efficiency solar cells. Moreover, the MoS_2/Si heterojunction exhibited good rectification characteristics and excellent photovoltaic effects. The power conversion efficiency of the heterojunction device is about 1.79% under white light illumination of 10 m W/cm^2. The results show that the monolayer MoS_2 film will find many applications in high-efficiency optoelectronic devices.展开更多
We calculated the room-temperature phonon thermal conductivity and phonon spectrum of alkyl group-functionalized zigzag graphene nanoribbons(ZGNRs) with molecular dynamics simulations. The increase in both chain lengt...We calculated the room-temperature phonon thermal conductivity and phonon spectrum of alkyl group-functionalized zigzag graphene nanoribbons(ZGNRs) with molecular dynamics simulations. The increase in both chain length and concentration of alkyl groups caused remarkable reduction of phonon thermal conductivity in functionalized ZGNRs. Phonon spectra analysis showed that functionalization of ZGNR with alkyl functional groups induced phonon–structural defect scattering, thus leading to the reduction of phonon thermal conductivity of ZGNR. Our study showed that surface functionalization is an effective routine to tune the phonon thermal conductivity of GNRs, which is useful in graphene thermal-related applications.展开更多
Information is given on thermal radiation from the Sun, considered in practical engineering calculations of heat exchange. It was found that although the surface temperature of the Sun is assumed to be about 5800 K, t...Information is given on thermal radiation from the Sun, considered in practical engineering calculations of heat exchange. It was found that although the surface temperature of the Sun is assumed to be about 5800 K, the solar spectrum data measured by Kondratyev lead to a value of at least 7134 K. Such a higher value can be obtained by interpreting the Planck formula for the black radiation spectrum for the Kondratyev data. In addition, using the Stefan-Boltzmann law, the energetic emissivity of the Sun’s surface was determined to be 0.431. Furthermore, based on Petela’s formulae for exergy of thermal radiation, the exergetic emissivity of the Sun’s surface was also calculated at the level of 0.426.展开更多
Solid solutions of In2（1-x）（HfMg）xMo3O12 are synthesized by solid state reaction with the aim to reduce the phase transition temperature of In2Mo3O12 and improve its thermal expansion property.The effects of（HfMg...Solid solutions of In2（1-x）（HfMg）xMo3O12 are synthesized by solid state reaction with the aim to reduce the phase transition temperature of In2Mo3O12 and improve its thermal expansion property.The effects of（HfMg）^6＋ incorporation on the phase transition and thermal expansion are investigated.It is shown that the monoclinic-to-orthorhombic phase transition temperature obviously decreases and the coefficient of thermal expansion（CTE） of the orthorhombic becomes less negative and approaches to zero with increasing the content of（HfMg）^6＋.A near zero thermal expansion covering the case at room temperature（RT） is achieved for the solid solutions with x ≥ 0.85,implying potential applications of this material in many fields.展开更多
文摘New results of two computer experiments on modeling of superthermal neutron-nuclear combustion of natural uranium for two different flux densities of external neutron source and duration of half a year each are presented. The simulation results demonstrate the dependence of the autowave combustion modes on the parameters of the external source.
文摘The effect of thermal shock, in an accelerated-corrosion environment spectrum, on the fatigue and corrosion behavior of 7B04-T6 aluminum alloy, was determined. The environment spectrum consists of two modules, namely： salt-spray corrosion and thermal shock. The effect of thermal shock on the mechanical properties was determined via tensile tests; SEM, DCS, and XRD were used to determine the effect of thermal shock on the corrosion products. In addition, the corrosion resistance of the products was ascertained through electrochemical testing. The results show that the mechanical properties and fatigue life of the aluminum alloy will decline with prolonged thermal shock time. The thermal shock process may result in denser surface corrosion products than those formed on the no thermal shock specimens, and transformation of some Al（OH）_3 into Al OOH. Al OOH may have resulted in improved corrosion resistance and hence a lower decrease in the fatigue life after corrosion, compared with that of the no thermal shock specimen. Repeated corrosion/thermal shock may have delayed further decease in the fatigue life. Therefore, selection of an appropriate equivalent thermal shock temperature and time was essential for designing the environmental spectrum.
基金This work was supported by the National Natural Science Foundation of China under grant No.60207006the Optical Science and Technology of Shanghai under grant No.022261046"Qiningxing”Projert(No.04QMX1448)of Shanghai Municipal Science and Technology Conmission.
文摘In this work, a new TeO2-BaO-BaF2-La2O3-LaF3 oxyfluorotellurite glass system is investigated. Differential thermal analysis (DTA) and structural analysis by Raman scattering spectra are reported on the glasses. The DTA results indicated that an increase of fluoride content in the glasses decreases the glass transition temperature (Tg) and increases the crystallization onset temperature (Tx). As a result the 70TeO2·20BaF2·10LaF3 glass showed a large Hruby's parameter, possessing excellent thermal stability. Changes in glass network structure with fluoride content are discussed based on the Raman scattering spectra of glasses. The glass network structures in the 70TeO2·4(20-x)BaO·xBaF2·(10-y)La2O3·yaF3 glasses are basically composed of both Te(O, F)4 and Te(O, F)3 units, but the Te(O, F)4/Te(O, F)3 ratio in the glass becomes higher with increasing fluoride content. This may be considered one of the reasons why the 70TeO2·20BaF2·10LaF3 glass exhibits excellent thermal stability.
基金supported in parts by the National Natural Science Foundation of China (No. 60976071)the Scientific Project Program of Suzhou City (No. SYG201121)
文摘We present a study of the fabrication of monolayer MoS_2 on n-Si(111) substrates by modified thermal evaporation deposition and the optoelectrical properties of the resulting film. The as-grown MoS_2 ultrathin film is about 10 nm thick, or about a few atomic layers of MoS_2. The film has a large optical absorption range of 300-700 nm and strong luminescence emission at 682 nm. The optical absorption range covered almost the entire ultraviolet to visible light range, which is very useful for making high-efficiency solar cells. Moreover, the MoS_2/Si heterojunction exhibited good rectification characteristics and excellent photovoltaic effects. The power conversion efficiency of the heterojunction device is about 1.79% under white light illumination of 10 m W/cm^2. The results show that the monolayer MoS_2 film will find many applications in high-efficiency optoelectronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.11504418)China Scholarship Council Scholarship Program(Grant No.201706425053)the Fundamental Research Funds for the Central Universities of China(Grant No.2015XKMS075)
文摘We calculated the room-temperature phonon thermal conductivity and phonon spectrum of alkyl group-functionalized zigzag graphene nanoribbons(ZGNRs) with molecular dynamics simulations. The increase in both chain length and concentration of alkyl groups caused remarkable reduction of phonon thermal conductivity in functionalized ZGNRs. Phonon spectra analysis showed that functionalization of ZGNR with alkyl functional groups induced phonon–structural defect scattering, thus leading to the reduction of phonon thermal conductivity of ZGNR. Our study showed that surface functionalization is an effective routine to tune the phonon thermal conductivity of GNRs, which is useful in graphene thermal-related applications.
文摘Information is given on thermal radiation from the Sun, considered in practical engineering calculations of heat exchange. It was found that although the surface temperature of the Sun is assumed to be about 5800 K, the solar spectrum data measured by Kondratyev lead to a value of at least 7134 K. Such a higher value can be obtained by interpreting the Planck formula for the black radiation spectrum for the Kondratyev data. In addition, using the Stefan-Boltzmann law, the energetic emissivity of the Sun’s surface was determined to be 0.431. Furthermore, based on Petela’s formulae for exergy of thermal radiation, the exergetic emissivity of the Sun’s surface was also calculated at the level of 0.426.
基金supported by the National Natural Science Foundation of China(Grant Nos.11574276,51302249,and 51503185)the Doctoral Fund of the Ministry of Education of China(Grant No.20114101110003)
文摘Solid solutions of In2（1-x）（HfMg）xMo3O12 are synthesized by solid state reaction with the aim to reduce the phase transition temperature of In2Mo3O12 and improve its thermal expansion property.The effects of（HfMg）^6＋ incorporation on the phase transition and thermal expansion are investigated.It is shown that the monoclinic-to-orthorhombic phase transition temperature obviously decreases and the coefficient of thermal expansion（CTE） of the orthorhombic becomes less negative and approaches to zero with increasing the content of（HfMg）^6＋.A near zero thermal expansion covering the case at room temperature（RT） is achieved for the solid solutions with x ≥ 0.85,implying potential applications of this material in many fields.
