等离子体摄谱分析法同时测定铅蓄电池板栅中微量元素

研究了用混酸(硝酸+酒石酸)快速分解试样,等离子体摄谱法同时测定蓄电池板栅铅钙合金中钙、锡、铝、镁、铜、铁、镍等微量元素的方法.方法检出限为1～1×10~(-4)μg·ml~(-1),相对标准偏差(RSD)小于3%,回收率为92%～107%.为铅蓄电池板栅中某些微量元素同时测定提供一个实用、可行的方法.     

碳限额及交易下零售商低碳宣传的双渠道供应链决策与协调

在碳限额及交易下,考虑制造商碳减排技术投入和零售商低碳宣传,分别构建了无低碳宣传成本分摊、低碳宣传成本分摊的分散决策和集中式决策博弈模型通过对模型的分析,指出通过碳减排成本和低碳宣传成本分摊能够实现双渠道供应链协调.研究结果表明:在碳限额及交易机制下,碳减排率与碳排放交易价格成正向变化关系,低碳宣传水平、双渠道供应链利润与碳排放交易价格成U变化关系;碳减排率、低碳宣传水平、双渠道供应链利润与消费者低碳偏好系数、低碳宣传对消费者的影响系数都成正向变化关系;碳减排率、低碳宣传水平、双渠道供应链利润都与低碳宣传成本、碳减排成本系数成反向变化关系.     

Typicality at quantum-critical points

We discuss the concept of typicality of quantum states at quantum-critical points, using projector Monte Carlo simulations of an S = 1/2 bilayer Heisenberg antiferromagnet as an illustration. With the projection(imaginary) time τ scaled as τ = a Lz, L being the system length and z the dynamic critical exponent(which takes the value z = 1 in the bilayer model studied here), a critical point can be identified which asymptotically flows to the correct location and universality class with increasing L, independently of the prefactor a and the initial state. Varying the proportionality factor a and the initial state only changes the cross-over behavior into the asymptotic large-L behavior. In some cases, choosing an optimal factor a may also lead to the vanishing of the leading finite-size corrections. The observation of typicality can be used to speed up simulations of quantum criticality, not only within the Monte Carlo approach but also with other numerical methods where imaginary-time evolution is employed, e.g., tensor network states, as it is not necessary to evolve fully to the ground state but only for sufficiently long times to reach the typicality regime.