Dynamic response of permalloy/Cu/Co magnetoresistive sandwiches

The dynamic response of trilayer magnetoresistive permalloy/Cu/Co films was studied by high-frequency permeability spectra measurements. The resonance frequency is shown to depend on the interlayer copper thickness. This dependence is related to exchange coupling between permalloy and cobalt and the interaction field is estimated using the Landau–Lifschitz–Gilbert model.     

Facile synthesis of SnO2–ZnO core–shell nanowires for enhanced ethanol-sensing performance

The design of core–shell heteronanostructures is powerful tool to control both the gas selectivity and the sensitivity due to their hybrid properties. In this work, the SnO₂–ZnO core–shell nanowires (NWs) were fabricated via two-step process comprising the thermal evaporation of the single crystalline SnO₂ NWs core and the spray-coating of the grainy polycrystalline ZnO shell for enhanced ethanol sensing performance. The as-obtained products were investigated by X-ray diffraction, scanning electron microscopy, and photoluminescence. The ethanol gas-sensing properties of pristine SnO₂ and ZnO–SnO₂ core–shell NW sensors were studied and compared. The gas response to 500 ppm ethanol of the core–shell NW sensor increased to 33.84, which was 12.5-fold higher than that of the pristine SnO₂ NW sensor. The selectivity of the core–shell NW sensor also improved. The response to 100 ppm ethanol was about 14.1, whereas the response to 100 ppm liquefied petroleum gas, NH₃, H₂, and CO was smaller, and ranged from 2.5 to 5.3. This indicates that the core–shell heterostructures have great potential for use as gas sensing materials.     

Design of an insensitive-polarization all-optical switch based on multimode interference structures

This paper presents a new design for an insensitive-polarization all-optical switch using 2 × 2 multimode interference (MMI) couplers. The switching structure can operate at central operating wavelength 1550 nm for both polarizations. A nonlinear directional coupler is used to realize the phase shifter and therefore switching mechanism is obtained. The transfer matrix method and beam propagation method are used to design and optimize the whole device structure.     

磁绝缘传输线电压的初步测量

针对快脉冲直线变压器驱动源装置上的真空磁绝缘传输线（MITL)电压测量的需求,开展了微分型电容分压器和电感分压器的设计、标定和实验。通过不同的电压值、负载阻抗的装置实验中探头输出结果的分析和比较,讨论了测量方法的可行性和适用范围。实验结果表明：微分型电容分压器能够应用于完全磁绝缘状态下的MITL电压测量,但容易受阴极电子发射的影响导致探头输出波形发生畸变。电感分压器受分布电容和电感的影响导致输出信号存在寄生振荡,采用波形重建的方法初步获得了合理的测量结果。     

Possible candidates for discrete gamma rays linking superdeformed and yrast states in an odd nucleus:193Pb

The francium isotopes^200–202Fr were produced in the reaction³⁵Cl+¹⁷⁰Yb using bombarding energies of 4.9–5.3 MeV/nucleon. Fusion products were separated in-flight from the primary beam using a gas-filled recoil separator. An alpha line with the alpha particle energy and half-life of (7468±9) keV and (19 ₋₆ ⁺¹³ ) ms, respectively, was assigned to²⁰⁰Fr. Previously reported decay properties of^201,202Fr were confirmed. Communicated by V. Metag     

Identifying Radix Curcumae by using terahertz spectroscopy

The absorption spectra from 0.2 THz to 1.6 THz of four kinds of similar Chinese herbs, including huangyujin, lvyujin, guiyujin and wenyujin, have been investigated by terahertz time-domain spectroscopy (THz-TDS). Furthermore, by using support vector machines (SVM) method, the linear kernel function, the polynomial kernel function, and the radial basis kernal function are employed for separating four kinds of Radix Curcumae. The calculated results show that the accuracy of discrimination for these four kinds of Chinese herbs is 100%.     

Experimental correlation between photoemission matrix elements and LEED intensities in superperiodic structures

A direct comparison between photoemission measurements and band structure calculations is sometimes tricky. Matrix element effects may affect considerably the spectral weight of the electronic states and prevent the expected translational symmetry of the band structure from being observed. We show how matrix element effects can be qualitatively described to a certain extent by making an analogy between photoemission and low energy electron diffraction. We have tested this approach in two superperiodic systems. We have first explained the intensity distribution in different Brillouin zones of a surface state in Si(1 1 1)-(7 × 7), where the surface state spectral intensity does not exhibit the (7 × 7) symmetry. We have also compared the LEED intensity of superperiodic LEED spots with the energy dependence of bulk bands on a facetted Si surface as measured by photoemission.     

Hopf bifurcation control via a dynamic state-feedback control

To relocate two Hopf bifurcation points, simultaneously, to any desired locations in n-dimensional nonlinear systems, a novel dynamic state-feedback control law is proposed. Analytical schemes to determine the control gains according to the conditions for the emergence of Hopf bifurcation are derived. To verify the effectiveness of the proposed control law, numerical examples are provided.