Transmission resonances in magnetic-barrier structures

Quantum transport properties of electrons in simple magnetic-barrier (MB) structures and in finite MB superlattices are investigated in detail. It is shown that there exists a transition of transmission resonances, i.e., from incomplete transmission resonances in simple MB structures consisting of unidentical blocks, to complete transmission resonances in comparatively complex MB structures (, n is the number of barriers). In simple unidentical block arrangements in double- and triple-MB structures we can also obtain complete transmission by properly adjusting parameters of the building blocks according to k_y-value (k_y is the wave vector in y direction). Strong suppression of the transmission and of the conductance is found in MB superlattices which are periodic arrangements of two different blocks. The resonance splitting effect in finite MB superlattices is examined. It is confirmed that the rule (i.e., for n-barrier tunneling the splitting would be (n-1)-fold) obtained in periodic electric superlattices can be extended to periodically arranged MB superlattices of identical blocks through which electrons with tunnel, and it is no longer proper for electrons with k _y <0 to tunnel. Received: 18 August 1997 / Revised: 20 September 1997 / Accepted: 13 October 1997     

The large deviations theorem and ergodicity

In this paper, some relationships between stochastic and topological properties of dynamical systems are studied. For a continuous map f from a compact metric space X into itself, we show that if f satisfies the large deviations theorem then it is topologically ergodic. Moreover, we introduce the topologically strong ergodicity, and prove that if f is a topologically strongly ergodic map satisfying the large deviations theorem then it is sensitively dependent on initial conditions.     

AFS-230E型原子荧光光度计测汞时盐酸引起的故障及故障排除

用AFS-230E型厦子荧光光度计测定汞时，使用相同规格但不同厂家生产的盐酸对测定结果影响较大。使用该仪器测汞时由于配制载流液时选用盐酸不当发生空白值过高的现象，影响汞的准确测定。在排除其它可能故障后，更换不同厂家生产的盐酸进行试验，选用汞空白值低的盐酸，故障排除。     

Four-channel coarse WDM for inter- and intra-satellite optical communications

A polymer volume grating-based four-channel coarse wavelength division multiplexer (WDM) for inter- and intra-satellite optical communication application is reported for the first time. This compact four-channel WDM device working at 0.83, 1.06, 1.34 and 1.55 μm is designed to build a complete optical link between two satellites, where wavelengths of 0.83 and 1.55 μm are used for data stream channels, 1.06 and 1.34 μm are used for inter- and intra-satellite connection. It is for the first time reported that a WDM device can cover such a large wavelength range in a single substrate. For transverse electric (TE) wave, the channel efficiencies at 0.83, 1.06, 1.34 and 1.55 μm are 55%, 40%, 35% and 45%, respectively. Channel efficiencies for transverse magnetic (TM) waves are 20% lower than those of TE waves on average. Wavelength shifts due to Doppler effect, temperature variations and radiation effects in space can be adequately accommodated.     

New Sorbent for Bilirubin Removal from Human Plasma： Albumin Immobilized Microporous Membranous PTFE Capillaries

In this study, we developed a tailored capillary sorbent for bilirubin removal. For immobilized bioligand, capillaries were grafted with epoxy groups using RIGP. The HSA immobilized capillaries has a high affinity adsorption capacity （71.2 mg bilirubin/g polymer） and a shorter adsorption equilibrium time （about 60 min）.     

Minimum time‐step criteria for the Galerkin finite element methods applied to one‐dimensional parabolic partial differential equations

The finite element method has been well established for numerically solving parabolic partial differential equations (PDEs). Also it is well known that a too large time step should not be chosen in order to obtain a stable and accurate numerical solution. In this article, accuracy analysis shows that a too small time step should not be chosen either for some time‐stepping schemes. Otherwise, the accuracy of the numerical solution cannot be improved or can even be worsened in some cases. Furthermore, the so‐called minimum time step criteria are established for the Crank‐Nicolson scheme, the Galerkin‐time scheme, and the backward‐difference scheme used in the temporal discretization. For the forward‐difference scheme, no minimum time step exists as far as the accuracy is concerned. In the accuracy analysis, no specific initial and boundary conditions are invoked so that such established criteria can be applied to the parabolic PDEs subject to any initial and boundary conditions. These minimum time step criteria are verified in a series of numerical experiments for a one‐dimensional transient field problem with a known analytical solution. The minimum time step criteria developed in this study are useful for choosing appropriate time steps in numerical simulations of practical engineering problems. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006     

Coherent population trapping states with cold atoms in a magnetic field

Using potassium atoms cooled with a MOT, ground-state hyperfine coherent population trapped (CPT) states were prepared in a magnetic (B) field, and the behavior of CPT states was experimentally studied. We carefully measured the preparation of the CPT state as a function of time and the CPT signal as a function of laser power. The experimental CPT signal linewidth was approximately proportional to the square root of laser intensity in the range of parameters studied, and limits of this relation were explored theoretically.     

DWDM用薄膜窄带滤光片的容差特性模拟分析

讨论了用于DWDM系统的薄膜窄带滤光片在镀制过程中的监控方法及误差产生的机理,利用自行建立的计算机膜厚容差模拟程序,分析了多FabryPerot腔窄带滤光片的容差特性.发现多腔窄带滤光片各腔的误差灵敏度与腔的位置有关,且各腔间隔层组成材料不同,其对误差最敏感的膜层位置也不相同.