无线传输芯片CC1100在继电器控制系统中的应用

为了实现继电器的无线控制,确保供电网络的安全运行,结合继电器保护、微处理器、无线通讯传输技术,研制了无线继电器控制系统.系统可以检测电路中的供电参数,并进行智能识别判断,控制相应的电路通断,起到保护电路的作用.     

CC双键对氟化非晶碳薄膜I-V特性的影响

研究了电子回旋共振等离子体技术沉积的氟化非晶碳 (a_C :F)薄膜的电学性质 .发现对于不同C_Fx 含量的薄膜 ,CC含量的增大对薄膜的导电行为具有不同的影响 .薄膜的直流I_V特性呈现I =aV bVn规律 ,是低场强区的欧姆导电和高场强区的空间电荷限流 (SCLC)组成的导电过程 .由于非晶材料的空间电荷限流与带尾态密度的分布密切相关 ,而a_C :F薄膜中CC的含量决定带尾态密度的分布 ,因此a_C :F薄膜在高场下的空间电荷限流是由薄膜中 CC 决定的导电过程 .     

Economic design of integrated model of control chart and maintenance management

There are two key tools for the control of production processes — Statistical Process Control (SPC) and Maintenance Management (MM), which are traditionally separated (both in science and in business practice), even though their goals overlap a great deal. Their common goal is to achieve optimal product quality, little downtime and cost reduction by controlling variances in the process. Since single or separated parallel applications may not be fully effective, this paper discusses the integration of statistical process control and maintenance, and provides an integrated model of Control Chart (CC) and MM. A mathematical model is given to analyze the cost of the integrated model and the grid-search approach is used to find the optimal values of policy variables (n,h,L,k) that minimize hourly cost. Finally, a numerical experiment is conducted to investigate the effects of cost parameters on the solution of the design.     

基于LPC2103的无线传感器网络节点设计

设计合理的网络节点是无限传感器网络的核心问题.根据无线传感器网络的工作原理和节点体系结构,设计了以32位ARM7处理器LPC2103为核心,结合2.4 GHz无线收发器CC2420、存储器AT45DB041以及外围数字温度传感器构建的无线传感器节点.并给出了节点软件部分的设计流程.     

TMS320C55x性能及DMA的使用

TMS320C55x是德州仪器公司的新一代高性能低功耗定点数字信号处理器。以TMS320C5509为例介绍了TMS320C55x系列的特点和性能指标,并重点介绍了DMA技术在C5509中的使用,最后给出DMA的编程实例。该实例中控制寄存器的定义和引用可用于对其他片内外设的编程。     

The virial theorem in refined Thomas－Fermi－Dirac theory for the interior of atoms in a solid

The virial theorem in refined Thomas－Fermi－Dirac theory for the interior of atoms in a solid is given and proven.     

The charge storage of the nc—Si layer

Sandwiched structures (a-SiN_x/a-Si/a-SiN_x) have been fabricated by the plasma enhanced chemical vapour deposition technique. A Si nanocrystal (nc-Si) layer was formed by crystallization of an a-Si layer according to the constrained crystallization principle after quasi-static thermal annealing at 1100℃ for 30 min. Transmission electron microscopy (TEM) and Raman scattering spectroscopy clearly demonstrated that nc-Si grains were formed in the as-deposited a-Si layer after annealing. The density of nc-Si grains is about 10¹¹cm^-2 as shown by TEM photographs. Using capacitance－voltage (C－V) measurements we investigated the electrical characteristics of the sandwiched structures. The charge storage phenomenon of the nc-Si layer was observed from the shift of flat-band voltage (V_FB) in C－V curves at a high frequency (1 MHz). We estimated the density of nc-Si grains to be about 10¹¹cm^-2 from the shift value of V_FB, which is in agreement with the result of TEM photographs. At the same time, we found that the shift of V_FB increased with the increase of the applied constant dc voltage or the thickness of the nc-Si layer.     

Investigation of the growth process of Si nanowires using the vapour－liquid－solid mechanism

Silicon nanowires have been grown by the thermal decomposition of silane via the vapour－liquid－solid (VLS) mechanism. Three different stages of VLS growth (eutectic alloy formation, crystal nucleation and unidirectional growth) were studied separately using a scanning electron microscope and a high-resolution transmission electron microscope. Very short silicon nanowires prepared under particular conditions provide direct evidence of the VLS mechanism on a nanometre scale. Our results will be very helpful for the controllable synthesis of Si nanowires.     

Second harmonic generation of propagating collective excitations in Bose－Einstein condensates

We consider a possible second harmonic generation (SHG) of propagating collective excitations in a two-component Bose－Einstein condensate (BEC) with repulsive atom－atom interactions. We show that the phase-matching condition for the SHG can be fulfilled if the wave vectors and frequencies of the excitations are chosen adequately from different dispersion branches. We solve the nonlinear amplitude equations for the SHG derived using a method of multiple-scales and provide SHG solutions similar to those obtained for a SHG in nonlinear optical media. A possible experimental realization of the SHG for the propagating collective modes in a cigar-shaped two-component BEC is also discussed.