质量量子基准的建立是计量科学领域的研究热点和难点。针对功率天平方案中准直部分进行了详细分析。首先介绍了功率天平的基本原理,并分析了功率天平实验中所涉及到的物理矢量;然后,结合NIST(NationalInstitute of Standard and Technology)功率天平线圈结构,给出了功率天平准直的物理含义,并通过对比理想情况与实际情况中功率天平的对应物理矢量的相互关系,分析了功率天平中存在的准直误差;根据功率天平研究的现状,总结了功率天平准直参数检测和调整的措施,并给出了对该领域研究最深入的英美两国在准直调整方面取得的研究成果;最后,详细分析了准直误差对中国计量科学研究院提出的能量天平方案的影响,并认为,前述准直参数检测和调整方法,对于其他国家功率天平以及能量天平准直参数的调整具有很好的借鉴意义。
We present the motion equation of the standard-beam balance oscillation system,whose beam and suspensions,compared with the compound pendulum,are connected flexibly and vertically.The nonlinearity and the periodic solution of the equation are discussed by the phase-plane analysis.We find that this kind of oscillation can be equivalent to a standard-beam compound pendulum without suspensions;however,the equivalent mass centre of the standard beam is extended.The derived periodic solution shows that the oscillation period is tightly related to the initial pivot energy and several systemic parameters:beam length,masses of the beam,and suspensions,and the beam mass centre.A numerical example is calculated.
