射流损失---小孔型脉冲管制冷机的一种重要损

脉冲管冷端和热端的层流化元件是脉冲管制冷机的重要部分。本文从流体力学、热力学出发,分析了小孔型脉冲管热端的流动过程和热力过程,确定了小孔型脉冲管的制冷机理。在此基础上,分析表明在脉冲管热端存在射流现象和涡流现象,导致一种气流混合的损失。本文称之为射流损失。设计了几种改进结构,实验验证了这种损失的存在同时也揭示了改进方法的有效性。     

磷扩散法制备P型ZnO薄膜

应用射频反应磁控溅射的方法,将ZnO薄膜沉积于高磷掺杂的n+型Si衬底上.在沉积和后退火过程中,磷向ZnO薄膜扩散并被激活,使ZnO薄膜由n型转化为p型,从而形成p型ZnO薄膜.X射线衍射分析(XRD)证明了所制备的ZnO薄膜都是高c轴取向的六角纤锌矿结构的薄膜.电学I-V关系曲线的整流特性和空穴浓度≥1.78×1018 /cm3的霍耳效应测试结果证明了p型ZnO薄膜的形成.     

Energy spectrum and entanglement of two tunnel- coupled Bose--Einstein condensates

This paper obtains the energy-spectrum and eigenstate corrections of two-mode Bose--Einstein condensates (BECs) coupled by quantum tunnelling by perturbation method in both strong and weak tunnelling regions. The population imbalance between two BECs are then studied in terms of the low-lying eigenstates which also characterize the intrinsic entanglement between the two-mode BECs. The strong parity effect in the weak tunnelling region is also investigated.     

Spin-polarized quantum transport through an Aharonov--Bohm quantum-dot-ring

In this paper the quantum transport through an Aharonov--Bohm (AB) quantum-dot-ring with two dot-array arms described by a single-band tight-binding Hamiltonian is investigated in the presence of additional magnetic fields applied to the dot-array arms to produce spin flip of electrons. A far richer interference pattern than that in the charge transport alone is found. Besides the usual AB oscillation the tunable spin polarization of the current by the magnetic flux is a new observation and is seen to be particularly useful in technical applications. The spectrum of transmission probability is modulated by the quantum dot numbers on the up-arc and down-arc of the ring, which, however, does not affect the period of the AB oscillation.     

铽配合物与PVK混合体系的发光研究

研究了铽配合物[Tb(m-MBA)₃phen]₂·2H₂O与PVK共掺杂体系的激发光谱和光致发光谱, 发现两者之间存在着能量转移,由于PVK的发射光谱和铽配合物的激发光谱重叠很小,两者之间发生Frester能量传递的几率很小,铽的发光主要是由于铽配合物的配体俘获了电子-空穴对使配体受到激发而导致的,在电致发光中, PVK的发光完全被抑制, 与光致发光的表现不同, 这是由于两种发光(光致和电致)机理不同造成的。     

Spin current in double quantum dot

We have studied the dynamical behaviours of two electrons confined in a double quantum dot driven by rotating magnetic fields in terms of the theory of Lewis－Riesenfeld Hermitian invariants for the explicitly time-dependent Hamiltonian. The coherent spin oscillations in the dot provide a generation source for spin current. Exact solutions obtained allow us to investigate the dynamical properties of the spin localization for various initial localized states.     

时序建模方法在滑油光谱分析中的应用

本文讨论了时序建模方法在机械设备滑油光谱分析中的应用。通过运用ＡＲ模型对采集的航空发动机滑油光谱数据进行时序建模和预测分析,获得了满意的效果。这一成果,为机械设备的状态监控和故障预报提供了一种实用方法。     

线性压缩机驱动的微型同轴脉冲管制冷机寿命试验

介绍了一种用于测试线性压缩机驱动的微型同轴脉冲管制冷机系统可靠性的试验系统 ,此试验台的建立将用来获得目前国内的同类系统的可靠性数据 ,为今后此种制冷系统用于国防、航空、航天打下基础     

聚噻吩/多壁碳纳米管复合材料结构与导电机理的研究

从结构和相互作用方面对聚噻吩(PTh)/多壁碳纳米管(MWNTs)复合材料进行了研究, 结果表明: 一方面聚噻吩本身的结构对其导电性能有一定的影响, 另一方面MWNTs作为一种掺杂剂, 和聚噻吩之间存在强的相互作用, 电子从MWNTs转移到聚噻吩. MWNTs和它周围被掺杂的聚噻吩通过π-π共轭作用形成相对独立的导电单元, 在复合材料的导电体系中起到主要作用, 随着这种导电单元数量的增加直至相互接触, 形成大的导电体系, 复合材料的电导率达到最大值.