Application of selective implantation in Al0.5Ga0.5As/In0.25Ga0.75As/GaAs pseudomorphic single quantum wire structures

A pseudomorphic Al0.5Ga0.5As/In0.25Ga0.75As/GaAs asymmetric quantum wire (QWR) structure was grown on GaAs V-grooved substrate by low pressure metal organic vapor phase epitaxy. The formation of crescent shaped QWRs at the bottom of the V-grooves was confirmed by both transmission electron microscopy and photoluminescence (PL) spectra. The temperature dependence of PL spectra demonstrated a fast decrease of the sidewall quantum well PL intensity with increasing temperature, which originates from relaxation of carriers from well to wire region. The self-aligned dual implantation technique was successfully used to selectively disable the adjacent quantum structures. Decrease of the PL intensity of QWR at 8 K was observed after selective implantation, which resulted from a decreased number of carriers relaxed from adjacent quantum structures.     

Synthesis of single-walled carbon nanotubes by arc-vaporization under high gravity condition

Arc-vaporization is one of the common methods to synthesize single-walled carbon nanotubes (SWNTs). However the detailed synthesis mechanism is still not clear, and the synthesis of longer and chirality-selected SWNTs has not been obtained. Here influence of the gravity G = 1 g₀, 2 g₀, and 3 g₀ is studied in order to develop the synthesis method of SWNTs. Simultaneously, calculations of heat convection are also carried out by using a fluid simulation program and the results are compared with the experimental results.     

On symbolic manipulation and code generation of a hybrid three-dimensional solid element

A symbolic procedure is utilized to derive the analytical expressions of the component matrices resulting to the closed-form integration of a stiffness matrix of a hybrid finite element. In order to alleviate the expression growth problem, we employ special techniques, including the use of symmetry conditions, pattern search, and introduction of intermediate variables, so that the final form of the derived stiffness matrix is suitable for coding implementation. Application of the symbolic procedure is made on a hybrid three-dimensional 8-node solid element. The same procedure is equally applicable to other types of hybrid elements.     

Design optimization and cold RF test of a 2.6-cell cryogenic RF gun

To further improve the performance of acceler-ators, the first cryogenic normal-conducting RF gun in China was designed and manufactured. As a new and attractiv...     

Recovery of PTUIE handling from source codes through recognizing its probable properties

Automated recovery of system features and their designs from program source codes is important in reverse engineering and system comprehension. It also helps in the testing of software. An error that is made by users in an input to an execution of a transaction and discovered only after the completion of the execution is called a posttransaction user-input error (PTUIE) of the transaction. For a transaction in any database application, usually, it is essential to-provide transactions for correcting the effect that could result from any PTUIE of the transaction. We discover some probable properties that exist between the control flow graph of a transaction and the control flow graphs of transactions for correcting PTUIE of the former transaction. Through recognizing these properties, we present a novel approach for the automated approximate recovery of provisions and designs for transactions to correct PTUIE of transactions in a database application. The approach recognizes these properties through analyzing the source codes of transactions in the database application statically.     

Further result on a dynamic recurrent neural-network-based adaptive observer for a class of nonlinear systems

In Kim et al. [(1997) A dynamic recurrent neural-network-based adaptive observer for a class of nonlinear systems. Automatica 33(8), 1539–1543], authors present an excellent neural network (NN) observer for a class of nonlinear systems. However, the output error equation in their paper is strictly positive real (SPR) which is restrictive assumption for nonlinear systems. In this note, by introducing a vector b₀ and Lyapunov equation, the observer design is obtained without requiring the SPR condition. Thus, our observer can be applied to a wider class of systems.     

蛋类膜-壳结构启发制备兼具高灵敏度和宽检测范围的应变传感

为了解决可拉伸应变传感器的灵敏度与检测范围(最大和最小可拉伸性)之间相互制约的问题.受蛋类膜-壳结构的启发,本文提出了一种构筑具有高灵敏度、宽可拉伸应变传感器的新策略,即基于柔性可拉伸的表面接枝聚吡咯膜(s-PPy)(类似于蛋膜)和脆性金膜(类似于蛋壳)制备器件.Au和s-PPy膜在电学和机械性能上产生相互协同作用.A...     

Terahertz Direct Modulation Techniques for High-speed Communication Systems

Terahertz communication technology can provide abundant frequency resources,strong confidentiality,antijamming capability,communication tracking capability and ...     

某宾馆空调冷热源方案比较

通过比较三种方案的初投资和运行费用,得出最佳的冷热源方案。     

脉冲光源原子吸收光谱仪信号数字处理软件的设计

通过实验室设计的脉冲光源钨丝原子吸收光谱仪,采集到一个分析信号和光源载波叠加的复合信号。为了从中提取原子吸收分析信号,首先对该复合信号进行数值微分,确定光源脉冲载波每个峰的坐标和相应的峰高,算出每个载波峰位相应的吸光度值,绘制吸收峰轮廓图;然后根据辛普森(Simpson)数值积分原理,求出吸收峰的面积,从而得到积分吸光度值。在微软公司的Visual Basic 6．0开发平台上,编写了实现上述功能的软件,以图形和数值的方式,同时输出每次测定结果。该软件系统和钨丝原子吸收光谱仪硬件系统相配合,对铜标准溶液的测试结果为:检出限为0．0133μg/ml,线性范围为0．10- 4．0μg／ml,对1．0μg／ml Cu(n=10)测定的精密度为RSD=4．05％。