Differential cross sections on fragment (2 ≤ Z ≤ 9) production for carbon,aluminum and silicon induced by tens-of-MeV protons

The double-differential cross sections (DDXs) for the inclusive reactions producing heavy nuclei with Z = 2–9 (fragments) from carbon, aluminum, and silicon targets induced by 50 and 70 MeV protons are systematically measured at several angles (30°, 60°, 90°, and 135°) using a specially developed Bragg curve counter and the energy-time-of-flight method. The DDXs of a silicon target for the proton-induced reaction producing fragments heavier than lithium were measured for the first time. The present results are compared with past experimental data, the LA150 evaluated data by the Los Alamos group and several intranuclear cascade models (Bertini and ISOBAR), and the JAEA-version quantum molecular dynamics model (JQMD) coupled with the Generalized Evaporation Model (GEM), which are implemented in the Particle and Heavy Ion Transport code System (PHITS). The present results agree well with the past experimental data and LA150 data for α -particle production. For the fragments heavier than lithium, the present results show forward-peak angular distributions rather than isotropic ones stored in LA150. Calculations with the ISOBAR and GEM models well reproduced our experimental results except for light fragments especially in the high-energy region.     

不同处理状态V-60%（TiCrFeMn）的吸放氢特性

热处理工艺是改变金属材料微观组织结构和性能的常用手段,考察了退火和淬火以及淬火加低温回火对用FeV80中间合金代替纯钒制备的V-60%（TiCrFeMn）贮氢合金循环性能的影响。与退火处理相比,合金初始吸放氢量和平台压在淬火后均出现下降,合金的容量保持率提高。通过淬火,合金的成分均匀性虽然得到了改善,但合金放氢后会出现TiH2化合物相,TiH2化合物相所储存的氢无法在测试条件下放出,导致淬火后合金放氢量偏小。淬火后再低温回火,消除了一部分晶格微应力,合金的性能有一定改善。     

我国煤炭采选业上市公司的经营效率研究

利用因子分析和数据包络分析相结合的方法,对我国2010年煤炭采选业22家上市公司的经营效率进行评价。通过因子分析把许多投入产出指标归并成若干个具有明确经济意义的公共因子。再利用DEA模型计算出各个决策单元的相对有效值,分析出哪些公司是DEA相对有效的,并进一步计算出DEA相对无效或弱有效的公司的投入冗余率与产出不足率。并探讨了提高煤炭采选业经营效率的方向和途径。     

Microstructure and hydrogen storage properties of (Ti0.32Cr0.43V0.25) + x wt% La (x = 0–10) alloys

The composite alloy of Ti_0.32Cr_0.43V_0.25 with x wt% La (where x = 0–10) was prepared by arc melting technique. The effect on hydrogen storage capacity, flatness of the plateau pressure, and residual hydrogen was investigated in La added Ti_0.32Cr_0.43V_0.25. Crystalline phase and microstructure of the prepared composite alloy were investigated and characterized by XRD, SEM and TEM. The crystal structure was refinement using Rietveld analysis. The effective hydrogen storage capacity of the composite alloy was found comparable to the parent alloy, when 5 wt% La was added. The effective hydrogen capacity (∼2.31 wt%) was close to that of the parent alloy (2.35 wt%) and the plateau slope was significantly improved from 30.5 of the parent alloy to 14.6. Appropriate mechanisms associated with the improved flatness by the La addition has been discussed in terms of the refined crystalline structure. Using TG/DTA method we have shown the differences in the interaction of residual hydrogen with the BCC phase of both parent alloy and 5 wt % La mixed alloy.     

一种含分布式电源的中低压配电网状态估计方法研究

为解决含分布式电源的中低压配电网中三相不平衡的状态估计问题,提出一种含分布式电源的中低压配电网状态估计方法。在包含分布式电源的中低压配电网中引入变压器等值模型,以节点注入电流方程为基础,建立了可同时处理三相三线制和三相四线制量测量的量测方程,扩大了其实用范围并提高了对系统的估计精度。其次,将直角坐标下线性零注入约束作为等式约束条件加入中低压配网状态估计模型中,使节点注入功率严格为零,并使计算过程得到简化。最后,采用细菌群体趋药性算法(BCC)对该模型进行状态估计。IEEE13节点修正系统算例的仿真结果验证了所提方法的有效性,且表明该方法具有良好的估计精度和收敛性。     

Effect of (Ti0.35V0.65)0.86Fe0.14Hy on synthesis and hydrogen storage properties of NaAlH4

The (Ti_0.35V_0.65)_0.86Fe_0.14H_y powder was prepared by melting, annealing and H₂-assisted-crushed method to avoid passivation. Then [(Ti_0.35V_0.65)_0.86Fe_0.14H_y]_x/100-NaAlH₄ composite system were synthesized using a two-step in-situ-milling method with the proportion of n (NaH):n (Al):n (Graphene):n (alloy) = 100:100:5:x (x = 2,5,8). It was found that lattice distortion had occurred on the alloy after 190hindividually milling, and the hydrogen storage capacity had decreased significantly to 1.10 wt%. However, after long-term composite milling, the alloy could still reduce the hydrogen pressure required for the synthesis of NaAlH₄, besides it could effectively reduce the hydriding/dehydriding temperature and improve the kinetic properties. This may due to the alloy's ability to dissociate H₂ and transfer H at room temperature, thereby enhancing the opportunity for direct contact between the matrix and H. In this study, x = 5 was the optimal alloy addition ratio, its dehydrogenation capacity at the 1st cycle reached 5.04 wt%; and at the 2nd and subsequent cycles, it remained rather stable at 4.40 wt%.