Influence of temperature on the microcrystalline structure of thermally evaporated Sb2S3 thin films

Thin films of antimony trisulfide (Sb₂S₃) were prepared by thermal evaporation under vacuum (p=5×10^–5 torr) on glass substrates maintained at various temperatures between 293 K and 523 K. Their microstructural properties have obtained by transmission electron microscopy (TEM). The electron diffraction analysis showed the occurrence of amorphous to polycrystalline transition in the films deposited at higher temperature of substrates (523 K). The polycrystalline thin films were found to have an orthorhombic structure. The interplanar distances and unit‐cell parameters were determined by high‐resolution transmission electron microscopy (HRTEM) and compared with the standard values for Sb₂S₃. The surface morphology of Sb₂S₃ thin films was investigated by scanning electron microscopy (SEM). The optical transmission spectra at normal incidence of Sb₂S₃ thin films have been measured in the spectral range of 400–1400 nm. The analysis of the absorption spectra revealed indirect energy gaps, characterizing of amorphous films, while the polycrystalline films exhibited direct energy gap. From the photon energy dependence of absorption coefficient, the optical band gap energy, E_g, were calculated for each thin films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

微型水声传感网水下传感器节点设计

针对在海洋环境监测系统中水声传感网高传输速率、高可靠性、长时间工作的要求,文中设计了一种低功耗的微型水下传感器节点。设计采用较高的能量转换率和接收灵敏度的换能器T235,并且在发送单元使用变压器进行阻抗匹配以使信号功率最大化传输。接收单元采用8阶巴特沃斯带通滤波器,可以更好地滤除噪声。软件上,移植并且优化了MAC协议,减少撞包和重发的概率。测试结果显示,在小规模范围内,传输速率在19 200 bit·s ^-1时,系统的总功耗低于20 W,能达到90%以上的通信传输成功率。     

Analytic Study of a Bose-Einstein Condensate in Waveguide with an Obstacle Potential

We investigate the exact solutions of one-dimensional （1D） time-independent Gross-Pitaevskii equation （GPE）, which governs a Bose-Einstein condensate （BEC） in the magnetic waveguide with a square-Sech potential. Both the bound state and transmission state are found and the corresponding spatial configurations and transport properties of BEC are analyzed. It is shown that the well-known absolute transmission of the linear system can occur in the considered nonlinear system.     

Deterministic Secure Quantum Communication with Cluster State and Bell-Basis Measurements

We present a novel protocol for deterministic secure quantum communication by using the lour-qubit cluster state as quantum channel. It is shown that two legitimate users can directly transmit the secret messages based on Bellbasis measurements and classical communication. The present protocol makes use of the ideas of block transmission and decoy particle checking technique. It has a high capacity as each cluster state can carry two 5its of information, and has a high intrinsic efficieney 5ecause almost all the instances except the decoy checking particles （its numSer is negligible） are useful. Furthermore, this protocol is feasible with present-day technique.     

Closed-form Analysis of Lossy Cosine-Squared Tapered Nonuniform Transmission Lines

The rigorous analytical solutions and the ABCD matrix of the lossy Cosine-Squared tapered nonuniform transmission lines (CSTNTL) are presented in this paper. According to different boundary conditions, the unique solution is obtained mathematically. Through the numerical calculations based on analytical solutions, the distributed voltages and currents in different terminated cases are shown to explain the transmission characteristics of CSTNTL. Especially in the lossy case the distributed power values are simulated to show the attenuation phenomenon.     

The transient suppression for piezoelectric ceramic emission transducer

A transient suppression method for piezoelectric ceramic transducer is presented. By adding some special pedestal pulses to the original transmitted signal, the transient effects in the output of the transducer can be just precisely transmission by use of a narrowband transducer. canceled, thereby achieving the broadband The experimental results show that the transient responses of the sinusoid pulses and coded signals are suppressed successfully and the acoustic waveforms radiated into the surrounding water are improved significantly.     

Evaluation of eigenvalues of a smooth potential via Schroedinger transmission across multi-step potential

In a one-dimensional quantal solution of Schroedinger equation, the general expressions for reflection and transmission coefficients are derived for a potential constituting n number of rectangular wells and barriers. These expressions are readily used for the estimation of eigenvalues of a smooth potential which is simulated by a multi-step potential. The applicability of this method is demonstrated with success in potentials with different forms including the most versatile Ginocchio potential where the widely used numerical method like Runge-Kutta integration algorithm fails to yield the result. Accurate evaluation of eigenvalues free from numerical problem for any form of potentials, whether analytically solvable or not, is the highlight of the present multi-step approximation method in the theory of potential scattering.      

Thermal impact on spiking properties in Hodgkin-Huxley neuron with synaptic stimulus

The effect of environmental temperature on neuronal spiking behaviors is investigated by numerically simulating the temperature dependence of spiking threshold of the Hodgkin-Huxley neuron subject to synaptic stimulus. We find that the spiking threshold exhibits a global minimum in a specific temperature range where spike initiation needs weakest synaptic strength, which form the engineering perspective indicates the occurrence of optimal use of synaptic transmission in the nervous system. We further explore the biophysical origin of this phenomenon associated with ion channel gating kinetics and also discuss its possible biological relevance in information processing in neuronal systems.      

Locally Resolving Measurements of PSD,Particle Concentration and Particle Velocity by Means of TFS with Dual Beams

Transmission fluctuation spectrometry with spatial correlation (TFS‐SC) is based on transmitting two beams of radiation through a flowing suspension, whereby the distance of the beam centers is varied. Thus, the spatial correlation of the transmission fluctuations of the two beams is determined as a function of the beam distance. By numerical modeling, the transition functions of the correlation are found as a function of beam distance, beam diameters, particle diameter and beam intersection angle. Experimentally determined spatial correlation spectra can be inverted to obtain the particle concentration and particle size distribution by using the theoretical transition functions for mono‐sized particles. In addition, time correlations can be used to extract information on particle velocity. Some experimental results obtained by TFS‐SC are presented and discussed. This method appears promising for application in the local resolving of measurements of PSD, particle concentration and particle velocity in two‐phase flows, both in the laboratory and in process control.     

亚波长分形结构太赫兹透射增强的机理研究

利用太赫兹时域光谱(terahertz time domain spectroscopy,简称THz-TDS),研究了亚波长金属分形结构在THz波段的透射增强特性.分别从实验和理论两个方面,研究了铜箔上各级分形结构THz透射增强现象的产生机理.结果表明,在低频区的透射增强主要是由低级分形线中电子运动的共振引起的,而高频区的透射增强则主要由高级分形线中电子运动的共振引起的.从而将这种透射增强效应归结为分形结构中电子的共振辐射,即分形结构的局域共振效应. 关键词： 分形 太赫兹 透射 共振峰