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移相干涉测量技术是一种众所周知的非接触式的高精密测量方法,具有广泛的应用范围。环境振动是移相干涉仪测量误差的主要来源之一,国际上一些从事干涉测量的工作人员提出了许多抗振的方法,大体上分为主动技术和被动技术。主动抗振技术主要是系统自身探测振动并通过反馈回路对振动进行补偿,被动抗振技术则是通过各种技术措施尽量减小干涉仪对环境振动和气流影响的敏感度。从这两方面对干涉仪的抗振技术研究的进展做简单介绍,并介绍了作者所在课题组在这两个方面所进行的研究工作。 相似文献
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利用同位旋相关量子分子动力学理论研究了中子晕核引起核反应机制中重要的同位旋效应以提取对称势. 因为同位旋相关量子分子动力学理论中的相互作用和介质中核子-核子碰撞截面都灵敏地依赖于碰撞系统的密度分布, 本项研究工作基于中子晕核扩展的密度分布. 该密度分布包含了反应机制中同位旋效应和疏散内部结构的平均特征. 为了弄清楚晕核引起核反应机制的同位旋效应, 在完全相同的入射道条件下, 比较了由中子晕核炮弹引起的同位旋效应和由相等质量的稳定核炮弹引起同位旋效应. 结果发现中子晕核炮弹引起的发射中子-质子比和同位旋分馏比明显大于相等质量稳定弹核产生的结果. 因而可以通过理论结果与实验数据的系统比较提取对称势. 相似文献
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Using the momentum- and isospin-dependent Boltmann-Uehling-Uhlenbeck (BUU) model, we investigate the transverse flow and balance energy in two isotopic colliding systems ^48Ca+^58Fe and ^48Cr+^58Ni by adopting different symmetry potentials. By comparing the results between the two colliding systems, we find that the difference between the balance energies of two isotopic systems can be considered as a sensitive probe to the density dependence of symmetry energy. 相似文献
998.
Single-crystalline wurtzite ZnS nanobelts are synthesized by the vapor phase transport (VPT) process. When oxidized, a single-crystalline ZnS nanobelt turns into a ZnO nanotwin belt containing two twinning parts with a sharp and clear edge, which is a (0001) twinning plane parallel to and running through the length direction. The two twinning parts in a ZnO nanotwin belt have the same crystalline direction, [0001], along their width, and the and crystalline directions along the length direction. On some ZnO nanobelts, nanovoids appear along the twinning planes and when those nanovoids connect with each other, one original ZnS nanobelt can divide into two single-crystalline ZnO nanobelts with quite clear edges. 相似文献
999.
The (0,0) and (0,1) bands of the C4Σ−-X4Σ− electronic transition of VS (near 809 and 846 nm, respectively) have been recorded at high resolution by laser-induced fluorescence, following the reaction of laser-ablated vanadium atoms with CS2 under supersonic free-jet conditions. A least squares fit to the resolved hyperfine components of the rotational lines gives the rotational constants and bond lengths as C4Σ−: , ; X4Σ−: , . The electron spin parameters for the two states show that there are some similarities between the states of VS and those of VO, but the hyperfine parameters show that the compositions of the partly filled molecular orbitals are by no means the same. The ground state Fermi contact parameter of VS, b(X4Σ−), is only 58% of that of the ground state of VO, which implies that the σ orbital of the ground σδ2 electron configuration has less than 50% vanadium 4s character. Similarly, the excited state Fermi contact parameter, b(C4Σ−), is very much smaller than that of VO. No local rotational perturbations have been found in the C4Σ− state of VS, though an internal hyperfine perturbation between the F2 and F3 electron components at low N confuses the hyperfine structure and induces some forbidden (ΔJ=±2) rotational branches. 相似文献
1000.
The 133Cs 1/2→−1/2 spin-lattice relaxation rate, , and the spin-spin relaxation rate, , for a Cs2CaCl4·2H2O single crystal have been measured in function of temperature. The dominant relaxation mechanism of this crystal over the whole temperature range investigated here proceeds via quadrupole interaction. The changes in the 133Cs spin-lattice relaxation rate near 325 K (=Tc1) and 360 K (=Tc2) correspond to phase transitions in the crystal. The change in the spin-lattice relaxation rate at Tc1 is small because the crystal lattice does not change very much during this phase transition. The change in near Tc2 is due to the critical slowing down of the soft mode that typically occurs in structural phase transitions. The temperature dependence of the spin-lattice relaxation rate for this crystal has maximum values at about 240 K, which is attributable to the effect of molecular motion as described by Bloembergen-Purcell-Pound theory. The phase transition temperatures Tc1 and Tc2 obtained from the temperature dependence of the relaxation rate is also clear from data obtained using differential scanning calorimetry. Therefore, we know that previously unreported phase transitions occur at 325 and 360 K. 相似文献