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141.
Neurons at rest can exhibit diverse firing activities
patterns in response to various external deterministic and random
stimuli, especially additional currents. In this paper, neuronal
firing patterns from bursting to spiking, induced by additional
direct and stochastic currents, are explored in rest states
corresponding to two values of the parameter $V_{\rm K}$ in the Chay
neuron system. Three cases are considered by numerical simulation
and fast/slow dynamic analysis, in which only the direct current
or the stochastic current exists, or the direct and
stochastic currents coexist. Meanwhile, several important bursting
patterns in neuronal experiments, such as the period-1
``circle/homoclinic" bursting and the integer multiple
``fold/homoclinic" bursting with one spike per burst, as well as
the transition from integer multiple bursting to period-1
``circle/homoclinic" bursting and that from stochastic
``Hopf/homoclinic" bursting to ``Hopf/homoclinic" bursting, are
investigated in detail. 相似文献
142.
A new way to enhance the directional stability of laser beams with alternating intensity by fast feedback control of both linear and angular drifts has been proposed for alignment of laser beams at higher accuracy. Both linear and angular drifts of laser beams, processed through light intensity modulation and primary alignment using single-mode optical fiber (SMOF), are separated using light path arrangement and detected using phase-lock technique, and are controlled using fast feedback control mechanisms according to their detected magnitudes, so that both linear and angular drifts are suppressed to enhance the directional stability of the emitting laser beams. Theoretical analyses and preliminary experimental results indicate that the approach proposed can be used to achieve an alignment accuracy of more than 10−8 rad. 相似文献
143.
Chih-Wei Lu 《Optics Communications》2006,259(1):281-285
We demonstrate experimentally and theoretically a method for enhancing the axial resolution of optical low-coherence reflectometry (OLCR) beyond the Fourier transform limit of light source spectrum. The resolution enhancement originates from the superposition of multiple OLCR scans with different offsets of the center-wavelength light-ray with respect to the rotation axis of the mirror mounted on the galvanometer optical scanner in the used optical phase delay line. After certain software process of the multiple scan fringe patterns of different offsets, the superposition leads to an OLCR axial resolution beyond the transform limit. Experimentally, by using four different offsets for superposition, about 1.5 times enhancement of the transform-limit resolution is obtained. 相似文献
144.
We present the lithography technique to fabricate a curved linear grating by using a Cartesian coordinates laser direct writer (LDW) system. The grating with the period of 15 μm is made on the convex lens surface. This is a new application of the LDW system. After the chromium coating and the photoresist removing procedures, a convex reflecting grating is obtained. 相似文献
145.
Min Zhang Aanying Ma Lu Bai Lewei Li Zhensen Wu 《International Journal of Infrared and Millimeter Waves》2005,26(5):701-713
We present an effective numerical technique to characterize the scattering of wide-slot antennas fed by waveguides with arbitrary terminations in terms of the method of moment (MoM) and the mixed potential integral equation (MPIE). In particular, the precorrected-fast Fourier transform (P-FFT) eliminates the need to generate and store the usual square impedance matrix andthus leads to speed up the matrix-vector multiplication in the resultant system. This property makes the Rao-Wilton-Glisson (RWG) functions to be useful in simulating electrically large-scale problems. In addition, the scattering from the finite ground surfaces is accounted for in the total scattered field by using the method of equivalent edge currents. The numerical results are presented and compared with both the traditional method of moment results obtained using the entire-domain basis functions and the experimental results, to demonstrate the proposed method to be a good candidate for study on the scattering of arbitrary wide-slot large array. 相似文献
146.
采用经典分子动力学方法模拟一定直径[111]晶向的硅纳米线填充不同扶手椅型单壁碳纳米管复合结构的加热过程, 通过可视化和能量分析的方法判断复合结构中硅纳米线和碳纳米管的热稳定性. 通过讨论碳纳米管的空间限制作用和分子间相互作用力的关系, 对碳纳米管和硅纳米线的热稳定性变化进行初步解释. 研究发现碳纳米管中硅纳米线的热稳定性和碳纳米管的直径关系密切: 当管径较小时, 硅纳米线的热稳定性有所提高, 当管径增大到一定大小时, 硅纳米线的热稳定性会突然显著地下降, 直到硅纳米线与管壁不存在分子间相互作用力, 硅纳米线的热稳定性才会恢复. 而硅纳米线填充到碳纳米管中对碳纳米管的热稳定性有着明显的降低作用. 相似文献
147.
Yu Gao Xiaodong Pi Xunhai Wang Tianhao Yuan Qingjun Jiang Jianguo Lu Deren Yang 《Particle & Particle Systems Characterization》2016,33(5):271-278
The doping of semiconductor nanocrystals (NCs) is crucial for the optimization of the performance of devices based on them. In contrast to recent progress on the doping of compound semiconductor NCs and silicon NCs, the doping of germanium (Ge) NCs has lagged behind. Here it is shown that Ge NCs can be doped with phosphorus (P) during synthesis by a nonthermal plasma. It is found that there are more P atoms in the NC near‐surface region than in the NC core. P doping modifies the surface state of Ge NCs. Compressive strain can be incuced in Ge NCs by P which can explain the P‐doping‐enhanced oxidation resistance of Ge NCs. Stable dispersions of P‐doped Ge NCs in acetonitrile can be cast to produce films for field‐effect transistors (FETs). FET analysis shows that the electrical conductivity and electron mobility of a Ge‐NC film increase with the increase of the P doping level, although the electrical activation efficiency of P in the Ge‐NC film is low. Finally, atomic layer deposition of aluminum oxide at the surface of P‐doped Ge NCs is shown to improve the performance of the FETs. 相似文献
148.
Tribological properties of diamond-like carbon films deposited by pulsed laser arc deposition 总被引:1,自引:0,他引:1 下载免费PDF全文
A novel method, pulsed laser arc deposition combining the advantages
of pulsed laser deposition and cathode vacuum arc techniques, was
used to deposit the diamond-like carbon (DLC) nanofilms with
different thicknesses. Spectroscopic ellipsometer, Auger electron
spectroscopy, x-ray photoelectron spectroscopy, Raman spectroscopy,
atomic force microscopy, scanning electron microscopy and
multi-functional friction and wear tester were employed to
investigate the physical and tribological properties of the deposited
films. The results show that the deposited films are amorphous and
the sp$^{2}$, sp$^{3}$ and C--O bonds at the top surface of the films
are identified. The Raman peak intensity and surface roughness
increase with increasing film thickness. Friction coefficients are
about 0.1, 0.15, 0.18, when the film thicknesses are in the range of
17--21~nm, 30--57~nm, 67--123~nm, respectively. This is attributed to
the united effects of substrate and surface roughness. The wear
mechanism of DLC films is mainly abrasive wear when film thickness
is in the range of 17--41~nm, while it transforms to abrasive
and adhesive wear, when the film thickness lies between 72 and 123~nm. 相似文献
149.
The electron transport characters in a nanostructure with the periodic magnetic-electric barriers 下载免费PDF全文
This paper detailedly studies the transmission probability, the spin
polarization and the conductance of the ballistic electron in a
nanostructure with the periodic magnetic-electric barriers. These
observable quantities are found to be strongly dependent not only on
the magnetic configuration, the incident electron energy and the
incident wave vector, but also on the number of the periodic
magnetic-electric barriers. The transmission coefficient and the spin
polarization show a periodic pattern with the increase of the
separation between two adjacent magnetic fields, and the resonance
splitting increases as the number of periods increases. Surprisingly,
it is found that a polarization can be achieved by spin-dependent
resonant tunnelling in this structure, although the average magnetic
field of the structure is zero. 相似文献
150.