On the basis of the survey of underground noise in Jinggezhuang and Donghuantuo mines, Kailuan Group, noise radiation intensity, noise propagation properties and noise frequency-spectrum characteristics of underground...On the basis of the survey of underground noise in Jinggezhuang and Donghuantuo mines, Kailuan Group, noise radiation intensity, noise propagation properties and noise frequency-spectrum characteristics of underground equipment were studied at different work conditions. The result indicates that the noise source intensity surpasses the noise limit requirement of 85 dBA completely. Nearly 70% noise sources exceed the noise limit of 90 dBA, and some are over 100 dBA. Noise attenua- tion in semi-free field environment on the ground is significantly different from underground far-field environment of noise source in coal mines. Noise of these regions, where staffs are long and highly concentrated, exceeds 85 dBA, the basic noise limit. The noise frequency-spectrum presents the wideband characteristics. Especially in the main frequency of the language communication 500, 1 000 and 2 000 Hz, the octave band of noise performs obviously.展开更多
A facile and efficient strategy was reported for the preparation of graphene nanosheets-Ag2S hybrid by a simple hydrothermal process. First, Ag2S particles deposited on the surface of graphene oxide（GO） sheet. GO wa...A facile and efficient strategy was reported for the preparation of graphene nanosheets-Ag2S hybrid by a simple hydrothermal process. First, Ag2S particles deposited on the surface of graphene oxide（GO） sheet. GO was then reduced by hydrazine hydrate to graphene. The results of X-ray diffraction（XRD） and Fourier transform infrared（FTIR） demonstrated the efficient reduction of GO to graphene. Transmission electron microscopy（TEM） image of the sample reveals the morphology of the architecture of graphene-Ag2S hybrid. Ultraviolet-visible spectroscopy（UV-Vis） and photoluminescence（PL） measurement were further employed to study the optical properties of the obtained nanocomposite. This work can be extended to design other graphene-based hybrid nanomaterials, and the as-grown architectures may hold promise for many applications.展开更多
Protons are emitted much more affluently in neutron-deficient system ^(40)Ar+^(112)Sn while triton emissions are greater in a neutron-rich system ^(40)Ar+^(124)Sn at incident energy of 30 MeV/u.Similar to neutron,prot...Protons are emitted much more affluently in neutron-deficient system ^(40)Ar+^(112)Sn while triton emissions are greater in a neutron-rich system ^(40)Ar+^(124)Sn at incident energy of 30 MeV/u.Similar to neutron,proton emission provied a dominant contribution to neutralize the system N/Z in the decay process of the hot nuclei.The emission of hydrogen isotopes with high energies is much enhanced in the ^(112)Sn system.The original temperature of the hot nuclei in the ^(40)Ar+^(112)Sn reaction is 5.8±0.3 MeV,about 0.7 MeV higher than 5.1±0.3 MeV as in the ^(40)Ar+^(124)Sn reaction.展开更多
The angular distributions of intermediate mass fragments with charge numbers from 3 to 24 emitted in 30 MeV/u 40Ar+58,64Ni and 115In reactions over an angular range of 5o-140ohave been measured.In different angular re...The angular distributions of intermediate mass fragments with charge numbers from 3 to 24 emitted in 30 MeV/u 40Ar+58,64Ni and 115In reactions over an angular range of 5o-140ohave been measured.In different angular region an exponential distribution function dσ/dΩ=N exp(-θ/α)was used to fit the measured angular distributions.The decay factor a which can be connected with the interaction time T and the factor N which is related to the intensity of the emission sources have been extracted.The relationship ofα(Z)and N(Z)with Z for different reaction systems and different angular regions has been discussed.The different behavior of dσ/dΩ,α(Z),and N(Z)for the three studied reaction systems exists mainly in the middle and backward angular regions.The dependencies of angular distributions on isospin and the size of reaction systems have also been discussed.展开更多
An inclusive measurement was performed for 30 MeV/u ^(40)Ar+^(58,64)Ni and ^(115)In.By employing the degree of freedom of N/Z,the production mechanism of the high energy component of the intermediate mass fragments(IM...An inclusive measurement was performed for 30 MeV/u ^(40)Ar+^(58,64)Ni and ^(115)In.By employing the degree of freedom of N/Z,the production mechanism of the high energy component of the intermediate mass fragments(IMFs:3≤Z≤13)has been discussed.Special attention has been paid to the target dependence of N/Z ratio of the energetic fragments.These IMFs may be produced by a projectile fragmentation process with energy dissipation.展开更多
The ratio of isotope yields integrated over a part of their energy spectrum is proposed to extract nuclear temperature of the excited emitter nucleus formed in heavy ion reactions.The nuclear temperature extracted fro...The ratio of isotope yields integrated over a part of their energy spectrum is proposed to extract nuclear temperature of the excited emitter nucleus formed in heavy ion reactions.The nuclear temperature extracted from the isotope ratio is consistent with that extracted from the relative populations of the particle unstable states.展开更多
In order to determine the characteristics of noise source accurately, the noisedistribution at different frequencies was determined by taking the differences into accountbetween aerodynamic noises, mechanical noise, e...In order to determine the characteristics of noise source accurately, the noisedistribution at different frequencies was determined by taking the differences into accountbetween aerodynamic noises, mechanical noise, electrical noise in terms of in frequencyand intensity.Designed a least squares wavelet with high precision and special effects forstrong interference zone (multi-source noise), which is applicable to strong noise analysisproduced by underground mine, and obtained distribution of noise in different frequencyand achieves good results.According to the results of decomposition, the characteristicsof noise sources production can be more accurately determined, which lays a good foundationfor the follow-up focused and targeted noise control, and provides a new methodthat is greatly applicable for testing and analyzing noise control.展开更多
基金Supported by the National Natural Science Foundation of China （50974061） the Natural Science Foundation of Hebei Province （E2009001420）
文摘On the basis of the survey of underground noise in Jinggezhuang and Donghuantuo mines, Kailuan Group, noise radiation intensity, noise propagation properties and noise frequency-spectrum characteristics of underground equipment were studied at different work conditions. The result indicates that the noise source intensity surpasses the noise limit requirement of 85 dBA completely. Nearly 70% noise sources exceed the noise limit of 90 dBA, and some are over 100 dBA. Noise attenua- tion in semi-free field environment on the ground is significantly different from underground far-field environment of noise source in coal mines. Noise of these regions, where staffs are long and highly concentrated, exceeds 85 dBA, the basic noise limit. The noise frequency-spectrum presents the wideband characteristics. Especially in the main frequency of the language communication 500, 1 000 and 2 000 Hz, the octave band of noise performs obviously.
基金Supported by the National High Technology Research and Development Program of China(No.2009AA03Z319)the Doctor Startup Fundation of Liaoning Province of China(No.20101010)the Fundamental Research Funds for the Central Universities of China(No.DUT12LK04)
文摘A facile and efficient strategy was reported for the preparation of graphene nanosheets-Ag2S hybrid by a simple hydrothermal process. First, Ag2S particles deposited on the surface of graphene oxide（GO） sheet. GO was then reduced by hydrazine hydrate to graphene. The results of X-ray diffraction（XRD） and Fourier transform infrared（FTIR） demonstrated the efficient reduction of GO to graphene. Transmission electron microscopy（TEM） image of the sample reveals the morphology of the architecture of graphene-Ag2S hybrid. Ultraviolet-visible spectroscopy（UV-Vis） and photoluminescence（PL） measurement were further employed to study the optical properties of the obtained nanocomposite. This work can be extended to design other graphene-based hybrid nanomaterials, and the as-grown architectures may hold promise for many applications.
基金Supported by the One Hundred Talents Project and Major Subjects of the Chinese Academy of Sciences under Grant No.KJ95T-03。
文摘Protons are emitted much more affluently in neutron-deficient system ^(40)Ar+^(112)Sn while triton emissions are greater in a neutron-rich system ^(40)Ar+^(124)Sn at incident energy of 30 MeV/u.Similar to neutron,proton emission provied a dominant contribution to neutralize the system N/Z in the decay process of the hot nuclei.The emission of hydrogen isotopes with high energies is much enhanced in the ^(112)Sn system.The original temperature of the hot nuclei in the ^(40)Ar+^(112)Sn reaction is 5.8±0.3 MeV,about 0.7 MeV higher than 5.1±0.3 MeV as in the ^(40)Ar+^(124)Sn reaction.
基金Supported by the National Natural Science Foundation of China under Grant No.19235012the Foundation of Chinese Academy of Sciences。
文摘The angular distributions of intermediate mass fragments with charge numbers from 3 to 24 emitted in 30 MeV/u 40Ar+58,64Ni and 115In reactions over an angular range of 5o-140ohave been measured.In different angular region an exponential distribution function dσ/dΩ=N exp(-θ/α)was used to fit the measured angular distributions.The decay factor a which can be connected with the interaction time T and the factor N which is related to the intensity of the emission sources have been extracted.The relationship ofα(Z)and N(Z)with Z for different reaction systems and different angular regions has been discussed.The different behavior of dσ/dΩ,α(Z),and N(Z)for the three studied reaction systems exists mainly in the middle and backward angular regions.The dependencies of angular distributions on isospin and the size of reaction systems have also been discussed.
基金Supported by the National Natural Science Foundation of China under Grant No.19205006.
文摘An inclusive measurement was performed for 30 MeV/u ^(40)Ar+^(58,64)Ni and ^(115)In.By employing the degree of freedom of N/Z,the production mechanism of the high energy component of the intermediate mass fragments(IMFs:3≤Z≤13)has been discussed.Special attention has been paid to the target dependence of N/Z ratio of the energetic fragments.These IMFs may be produced by a projectile fragmentation process with energy dissipation.
基金Supported by the National Natural Science Foundation of China.
文摘The ratio of isotope yields integrated over a part of their energy spectrum is proposed to extract nuclear temperature of the excited emitter nucleus formed in heavy ion reactions.The nuclear temperature extracted from the isotope ratio is consistent with that extracted from the relative populations of the particle unstable states.
基金Supported by the National Natural Science Fundation of China(50974061)the Natural Science Fundation of Hebei Province(E2009001420)
文摘In order to determine the characteristics of noise source accurately, the noisedistribution at different frequencies was determined by taking the differences into accountbetween aerodynamic noises, mechanical noise, electrical noise in terms of in frequencyand intensity.Designed a least squares wavelet with high precision and special effects forstrong interference zone (multi-source noise), which is applicable to strong noise analysisproduced by underground mine, and obtained distribution of noise in different frequencyand achieves good results.According to the results of decomposition, the characteristicsof noise sources production can be more accurately determined, which lays a good foundationfor the follow-up focused and targeted noise control, and provides a new methodthat is greatly applicable for testing and analyzing noise control.
