The effects of partial substitution of La by Ce and Ni by Al, Fe, or Co in LaNi_5-based alloys on hydrogen storage performance were systematically studied. All samples were prepared using vacuum arc melting in an argo...The effects of partial substitution of La by Ce and Ni by Al, Fe, or Co in LaNi_5-based alloys on hydrogen storage performance were systematically studied. All samples were prepared using vacuum arc melting in an argon atmosphere. The results showed that for LaNi_(5-x)M_x(M = Al, Fe, or Co) alloys, the lattice constants and unit cell volumes increased with an increasing amount of Al and Fe. On the other hand, these parameters decreased upon partial substitution of La by Ce. In addition, the lattice constant remained almost constant in the La_(0.6)Ce_(0.4)Ni_(5–x)Cox alloys regardless of the value of x(x = 0.3, 0.6, or 0.9), as Ce might enhance the homogeneity of the CaCu_5-type phase in Co-containing alloys. The hydrogen storage properties of the alloys were investigated using pressure, composition, and temperature isotherms. The experimental results showed that the plateau pressure decreased with an increasing content of Al, Fe, or Co, but it increased with Ce addition. Furthermore, the plateau pressures of all Co-containing alloys were almost identical upon substitution with Ce. Finally, the enthalpy(ΔH) and entropy(ΔS) values for all alloys were calculated using van't Hoff plots. The relationship between the lattice parameters and enthalpy changes for hydrogenation will be discussed.展开更多
Investigation of alloy structure shows that La2-xMgxNi7 （x = 0.3 - 0.8） alloys are mainly com- posed of Ce/Ni7-type, Gd2Co7-type and PuNi3-type phase. The influence of Mg content in alloys on the phase structure is ...Investigation of alloy structure shows that La2-xMgxNi7 （x = 0.3 - 0.8） alloys are mainly com- posed of Ce/Ni7-type, Gd2Co7-type and PuNi3-type phase. The influence of Mg content in alloys on the phase structure is great, resulting in a linear decrease of the unit cell parameters of main phases and increase of hydrogen absorption/desorption plateau as Mg content increases. Electrochemical measurements show that as the Mg content increases, the discharge capacity of alloy electrodes first increases and then decreases. The cyclic stability presents a deteriorative trend. La1.4Mg0.6 Ni7 alloy electrode exhibits the maximum electrochemical discharge capacity （378 mAh·g^-1）, and the La1.6Mg0.4Ni7 alloy electrode shows the best cyclic stability （S270 = 81%）.展开更多
The structure and electrochemical properties of the La0.7Mg0.3Ni3.4-xMn0.1Cox （x=01.05） hydrogen storage alloys were investigated. The crystal structure and the lattice parameters of the alloys were analyzed by X-ra...The structure and electrochemical properties of the La0.7Mg0.3Ni3.4-xMn0.1Cox （x=01.05） hydrogen storage alloys were investigated. The crystal structure and the lattice parameters of the alloys were analyzed by X-ray diffractometry and Rietveld method. Electrochemical properties of the alloys including p—c—t curves, discharge capacity, discharge capacity retention were studied. The results show that （La, Mg）Ni3 and LaNi5 are the main phases of all the alloys. The plateau pressure for hydrogen absorption/desorption decreases and the hydrogen storage capacity firstly increases and subsequently decreases with increasing Co content. The values of the maximum discharge capacity of the alloy electrodes remain in range of 395.3403.1mA·h/g in spite of the change of Co content. The cycling stability of the alloy electrodes is greatly improved with increasing Co content, which is attributed to the suppression of the cell volume expansion during hydriding, leading the pulverization of the alloy particles lowered and the oxidation/corrosion of the active elements reduced.展开更多
The annealing treatment was found to improve the cyclic stability but to degmde discharpe capacity, activation and high-rate discharpeability for the Ti-substituted AB2type alloy electrode. A larper polarization was f...The annealing treatment was found to improve the cyclic stability but to degmde discharpe capacity, activation and high-rate discharpeability for the Ti-substituted AB2type alloy electrode. A larper polarization was found in the annealed alloy because of its poor discharpe kinetics resulted hem the structural homogeneity. At larae discharpe cumnts, the hydmpen dchsion in the bulk of the alloy was mpaofed as the mte-determining step. Based on the P ressure-composition isotherm measurement, we concluded that the decrease in discharpeability of the annealed alloy is owing to the low and flat pressure plateau, as well as the large hysteresis, but the hydrgen stomge density almost remains unchangeable after annealing.展开更多
In [3], they gave necessary and sufficient condition for T 1 C and then as applications T 1 C for weakly dependent sequences was established. In this note, based on Gozlan-L′eonard characterization for W 1 H -inequal...In [3], they gave necessary and sufficient condition for T 1 C and then as applications T 1 C for weakly dependent sequences was established. In this note, based on Gozlan-L′eonard characterization for W 1 H -inequalities, we extends this result to W 1 H inequalities.展开更多
针对测地线活动轮廓(geodesic active contour,GAC)模型轮廓演化速度慢的问题,构造一个区域灰度相似性信息项,对GAC模型的能量泛函进行改进,加快轮廓演化速度,将其用于肺部薄扫CT(computed tomography)图像序列中肺实质的自动分割。采...针对测地线活动轮廓(geodesic active contour,GAC)模型轮廓演化速度慢的问题,构造一个区域灰度相似性信息项,对GAC模型的能量泛函进行改进,加快轮廓演化速度,将其用于肺部薄扫CT(computed tomography)图像序列中肺实质的自动分割。采用基于Nystrom逼近的谱聚类算法分割CT图像序列中间位置CT中的肺实质,计算其灰度均值与标准差,构造区域灰度相似性信息项,以分割好的肺实质轮廓作为初始轮廓,分别从上下两个方向采用改进了能量泛函的GAC模型实现其它切片中肺实质的分割。实验结果表明,该方法能够较好实现肺实质的自动分割,与医师分割结果的重合率可达94.83%,时间消耗较少。展开更多
基金partially supported by International Academic Exchange Program of Muroran Institute of Technology,Muroran(Japan)University of Science and Technology Beijing,Beijing(China)+1 种基金Environmentally Friendly Materials Education Program provided by Muroran MATERIAsupported by Beijing Key Laboratory of Energy Conservation and Emission Reduction for Metallurgical Industry,Beijing,China
文摘The effects of partial substitution of La by Ce and Ni by Al, Fe, or Co in LaNi_5-based alloys on hydrogen storage performance were systematically studied. All samples were prepared using vacuum arc melting in an argon atmosphere. The results showed that for LaNi_(5-x)M_x(M = Al, Fe, or Co) alloys, the lattice constants and unit cell volumes increased with an increasing amount of Al and Fe. On the other hand, these parameters decreased upon partial substitution of La by Ce. In addition, the lattice constant remained almost constant in the La_(0.6)Ce_(0.4)Ni_(5–x)Cox alloys regardless of the value of x(x = 0.3, 0.6, or 0.9), as Ce might enhance the homogeneity of the CaCu_5-type phase in Co-containing alloys. The hydrogen storage properties of the alloys were investigated using pressure, composition, and temperature isotherms. The experimental results showed that the plateau pressure decreased with an increasing content of Al, Fe, or Co, but it increased with Ce addition. Furthermore, the plateau pressures of all Co-containing alloys were almost identical upon substitution with Ce. Finally, the enthalpy(ΔH) and entropy(ΔS) values for all alloys were calculated using van't Hoff plots. The relationship between the lattice parameters and enthalpy changes for hydrogenation will be discussed.
文摘Investigation of alloy structure shows that La2-xMgxNi7 （x = 0.3 - 0.8） alloys are mainly com- posed of Ce/Ni7-type, Gd2Co7-type and PuNi3-type phase. The influence of Mg content in alloys on the phase structure is great, resulting in a linear decrease of the unit cell parameters of main phases and increase of hydrogen absorption/desorption plateau as Mg content increases. Electrochemical measurements show that as the Mg content increases, the discharge capacity of alloy electrodes first increases and then decreases. The cyclic stability presents a deteriorative trend. La1.4Mg0.6 Ni7 alloy electrode exhibits the maximum electrochemical discharge capacity （378 mAh·g^-1）, and the La1.6Mg0.4Ni7 alloy electrode shows the best cyclic stability （S270 = 81%）.
文摘The structure and electrochemical properties of the La0.7Mg0.3Ni3.4-xMn0.1Cox （x=01.05） hydrogen storage alloys were investigated. The crystal structure and the lattice parameters of the alloys were analyzed by X-ray diffractometry and Rietveld method. Electrochemical properties of the alloys including p—c—t curves, discharge capacity, discharge capacity retention were studied. The results show that （La, Mg）Ni3 and LaNi5 are the main phases of all the alloys. The plateau pressure for hydrogen absorption/desorption decreases and the hydrogen storage capacity firstly increases and subsequently decreases with increasing Co content. The values of the maximum discharge capacity of the alloy electrodes remain in range of 395.3403.1mA·h/g in spite of the change of Co content. The cycling stability of the alloy electrodes is greatly improved with increasing Co content, which is attributed to the suppression of the cell volume expansion during hydriding, leading the pulverization of the alloy particles lowered and the oxidation/corrosion of the active elements reduced.
文摘The annealing treatment was found to improve the cyclic stability but to degmde discharpe capacity, activation and high-rate discharpeability for the Ti-substituted AB2type alloy electrode. A larper polarization was found in the annealed alloy because of its poor discharpe kinetics resulted hem the structural homogeneity. At larae discharpe cumnts, the hydmpen dchsion in the bulk of the alloy was mpaofed as the mte-determining step. Based on the P ressure-composition isotherm measurement, we concluded that the decrease in discharpeability of the annealed alloy is owing to the low and flat pressure plateau, as well as the large hysteresis, but the hydrgen stomge density almost remains unchangeable after annealing.
文摘In [3], they gave necessary and sufficient condition for T 1 C and then as applications T 1 C for weakly dependent sequences was established. In this note, based on Gozlan-L′eonard characterization for W 1 H -inequalities, we extends this result to W 1 H inequalities.
文摘针对测地线活动轮廓(geodesic active contour,GAC)模型轮廓演化速度慢的问题,构造一个区域灰度相似性信息项,对GAC模型的能量泛函进行改进,加快轮廓演化速度,将其用于肺部薄扫CT(computed tomography)图像序列中肺实质的自动分割。采用基于Nystrom逼近的谱聚类算法分割CT图像序列中间位置CT中的肺实质,计算其灰度均值与标准差,构造区域灰度相似性信息项,以分割好的肺实质轮廓作为初始轮廓,分别从上下两个方向采用改进了能量泛函的GAC模型实现其它切片中肺实质的分割。实验结果表明,该方法能够较好实现肺实质的自动分割,与医师分割结果的重合率可达94.83%,时间消耗较少。
