Amorphous NiB andNiBRE alloys were prepared bychemical reduction method. Theeffects of Eu, Gd, Tb on thecatalytic activity and suifur resistance of amorphous NiB alloywere studied for the first time inthe paper. XRD w...Amorphous NiB andNiBRE alloys were prepared bychemical reduction method. Theeffects of Eu, Gd, Tb on thecatalytic activity and suifur resistance of amorphous NiB alloywere studied for the first time inthe paper. XRD was used to examine the structure. The surfaceproperties of the alloys were charaeterized by TPR and TPD. Results indicate that the addition ofa small amount of rare earth elements improves the activity andsulfur resistance of amorphousNiB alloy because of the interaction between RE and NiB alloy.It makes oxidized nickel and NiB-O species reduce more easilyand difficultly, respectively,whieh increases the number of active sites. It also changes thestrength of absorbing bond and decreases the activation energy forbenzene hydrogenation over NiB alloy. The results also indicate thatthe active sites of NiB alloy are related to the reduced nickel and NiB-O species.展开更多
By using the concept of complex sound intensity, the rotational character of the active sound intensity which is the real component of the complex sound intensity is descussed in this paper. It is shown that it is the...By using the concept of complex sound intensity, the rotational character of the active sound intensity which is the real component of the complex sound intensity is descussed in this paper. It is shown that it is the irrotational component of the active sound intensity that transfers sound energy in sound field. When sound power is measured with the two- microphone technique, the rotation of the active sound intensity has an effect on it. Because the irrotational component of the active sound intensity depends only on the surface sound intensity, measuring the surface sound intensity can avoid the effect of the rotation. Based on atuo- power spectra, formulas about the surface sound intensity are given in this paper, providing a theoretical basis for measuring the surface sound intensity.展开更多
文摘Amorphous NiB andNiBRE alloys were prepared bychemical reduction method. Theeffects of Eu, Gd, Tb on thecatalytic activity and suifur resistance of amorphous NiB alloywere studied for the first time inthe paper. XRD was used to examine the structure. The surfaceproperties of the alloys were charaeterized by TPR and TPD. Results indicate that the addition ofa small amount of rare earth elements improves the activity andsulfur resistance of amorphousNiB alloy because of the interaction between RE and NiB alloy.It makes oxidized nickel and NiB-O species reduce more easilyand difficultly, respectively,whieh increases the number of active sites. It also changes thestrength of absorbing bond and decreases the activation energy forbenzene hydrogenation over NiB alloy. The results also indicate thatthe active sites of NiB alloy are related to the reduced nickel and NiB-O species.
文摘By using the concept of complex sound intensity, the rotational character of the active sound intensity which is the real component of the complex sound intensity is descussed in this paper. It is shown that it is the irrotational component of the active sound intensity that transfers sound energy in sound field. When sound power is measured with the two- microphone technique, the rotation of the active sound intensity has an effect on it. Because the irrotational component of the active sound intensity depends only on the surface sound intensity, measuring the surface sound intensity can avoid the effect of the rotation. Based on atuo- power spectra, formulas about the surface sound intensity are given in this paper, providing a theoretical basis for measuring the surface sound intensity.
