MUX-DEMUX using a Spatial Wave-Function Switched Field Effect Transistor (SWSFET)

A spatial wave-function switched field effect transistor (SWSFET) conducts through different channels within its structure. The switching of charge carriers between different channels can be controlled by the gate voltage. The self-consistent Schrodinger and Poisson equation solution can explain the switching of charge population in different channels of a SWSFET. A circuit model is developed by modifying the BSIM 3.2.2 IGFET (Insulated Gate Field Effect Transistor) model. Different circuits can be designed for a SWSFET with less circuit elements than conventional CMOS. The innovative circuit design using the SWSFET can make only electrons participate in the circuit operation with better performance. This work discusses the design of an ultrafast 3-in-1 multiplexer and 1-to-3 demultiplexer using the SWSFET where only one SWSFET is used to design the circuit.     

Impedance model of electrolyte-insulator-semiconductor structure with porous silicon semiconductor

We present a generic impedance model for the porous silicon|electrolyte structure that is valid for a range of interfacial layers and bias in these structures. The model is validated using three widely different porous structures: short irregular silicon columns and pores, long cylindrical silicon columns and pores; and branched interconnected silicon microchannels and voids in a mesh structure. The model incorporates appropriate RC or constant phase elements for the different parts of the porous structure, namely, the top of the silicon columns (channels)|electrolyte, the column (channel) walls|electrolyte in the pores/channels, and the electrolyte|semiconductor interface at the base of the pores/channels. This physical model underscores the effects of column/channel depletion and accumulation, either due to applied bias or change of surface charge, to the impedance spectra of the device. The model helps to explain why the porosity needs to be optimized for specific applications and helps as a measurement tool for optimization.     

一种基于可编程计数阵列和最小二乘法的模数转换器

设计了一款软硬件结合的八位模数转换器。分析了脉宽调制波形的特性,研究了可编程计数阵列的工作原理,建立了系统实现的理论模型。经过理论分析和实际测试,设计了系统硬件电路。对硬件系统进行了抽样测试,并将抽样数据与理论值进行对比研究。采用最小二乘法对抽样数据进行拟合,对拟合结果进行对比分析研究,建立了优化的模数转换数学模型。在Keilv4平台上,设计了模数转换的软件系统。在某钢化玻璃加热炉上得到应用,系统工作稳定可靠。     

远程数据采集模块——电源设计

本文在对太阳电池输出特性和蓄电池充电特性分析的基础上,介绍了蓄电池充电特性和充电方式,设计了一种可对铅酸蓄电池实现浮充的低成本智能充电器设计方案,结合主电路和单片机控制方案阐述了其控制和保护策略。     

简易通信转换器的设计

为了实现不同通信模式设备之间的相互通信,介绍一款实用的简易通信转换器的设计,包括通信原理分析、电路实现及软件编制等内容。     

Potential distribution model for rechargeable sulphur electrodes in sodium-sulphur cells

The efficiency of laboratory type sodium-sulphur cells, especially the utilization of reactants, is critically dependent upon the design of the sulphur electrode. The satisfactory rechargeability of a new design, based on a graduated electronic resistance inside the carbon fibre matrix is analysed in terms of two models: (a) predominant influence of potential distribution, (b) predominant influence of free flow in open spaces. Experimental results in favour of model (a) are discussed. The potential distribution of the new design is computed using appropriate assumptions for the one-phase region and compared with that in the absence of a graduated electronic resistance. It appears that the improved rechargeability can be explained by the different potential distribution.     

The effect of flow arrangement on the pressure drop of plate heat exchangers

For the optimal design of plate heat exchangers (PHEs), an accurate thermal-hydraulic model that takes into account the effect of the flow arrangement on the heat load and pressure drop is necessary. In the present study, the effect of the flow arrangement on the pressure drop of a PHE is investigated. Thirty two different arrangements were experimentally tested using a laboratory scale PHE with flat plates. The experimental data was used for (a) determination of an empirical correlation for the effect of the number of passes and number of flow channels per pass on the pressure drop; (b) validation of a friction factor model through parameter estimation; and (c) comparison with the simulation results obtained with a CFD (computational fluid dynamics) model of the PHE. All three approaches resulted in a good agreement between experimental and predicted values of pressure drop. Moreover, the CFD model is used for evaluating the flow maldistribution in a PHE with two channels per pass.     

高精度数控直流稳压电源的设计与实现

基于单片机AT89S51设计了一种高精度数控直流稳压电源,数控部分采用12位高精度D/A转换器TLV5616控制稳压电路的输出电压;采用12位高精度A/D转换器TLC2543测量输出电压;采用矩阵式键盘作为电压的设定装置;采用LCD1602型液晶显示屏显示设定的电压和实际输出电压;电源以电压串联反馈式稳压电路为基础,并在系统中设计了过流保护电路。     

Transport analysis in reverse electrodialysis with pulsatile flows for enhanced power generation

Time-dependent velocity profile and concentration distributions formed in a single reverse electrodialysis (RED) unit have been successfully pursued using simulation framework for evaluating performance of the unit, i.e., open circuit voltage and short circuit current. The single RED unit consists of two adjunct fluid channels, separated by the semi-permeable membrane. Through one of the channels, sea water flows, and the other is occupied by fresh water, flowing in the opposite direction (countercurrent operation). The diffusion-convection transport of the rate-limiting ion, Na+ in this study, for both channels is treated. The diffusive transport of cation across the membrane is expressed as boundary conditions for the bi-mechanism model. Our simulations conducted using an orthogonal collocation on finite element scheme show that the concentration difference of 35 g/L between sea water and fresh water results in the open circuit voltage of 63 mV and the short circuit current density of 11.5 A/m². These values are close to ones that were obtained from the experiments.     

Hydrodynamic separation of particles using pinched‐flow fractionation

Rigid particles transported through a pinched‐flow fractionation (PFF) device are simulated using boundary‐integral methods (BIM). The PFF device separates particles by size using a bifurcated microfluidic channel. The critical flow ratio of the two input channels required to achieve complete separation of large and small particles decreases with increasing diameter of the larger particles relative to the pinch height, and is nearly independent of the smaller particle size. A narrow pinch with a square exit was shown to have the lowest critical flow ratio and was selected as the model device to be fabricated. Experiments conducted using this device confirm that the larger particles exit further from the top wall than do the smaller particles, due to steric exclusion, and the final exit positions are within a few percent of the simulation results. It is shown that BIM is a valuable tool in the design of microfluidic devices. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3444–3457, 2013     

Studies on corrosion control of naphtha fractions in overhead condensing system using laboratory distillation device

Corrosion in the overhead condensing system of atmospheric distillation units is a common occurrence in petroleum refineries worldwide. These corrosion problems are influenced by the presence of three phases: vapours, liquid hydrocarbons and aqueous phase containing hydrochloric acid formed during distillation by decomposition of chloride salts of calcium and magnesium.Present studies highlight the corrosion control of naphtha fractions of Bombay High and Dubai crude oils in laboratory distillation device by chemical treatment using various corrosion inhibitors having different functional groups. These studies were carried out using two phase systems (aqueous-hydrocarbon) in the distillation device having facilities for monitoring the corrosion and temperatures in vapour condensing region and liquid condensate. Corrosion monitoring was carried out by potentiodynamic polarization technique and dissolved iron analysis using inductively coupled plasma atomic emission spectroscopy (ICPAES). Experimental findings indicate that Dubai naphtha fraction is more corrosive in nature when compared to Bombay High naphtha. This observation can also be explained on the basis of characterization of both crude oils and their naphtha fractions. At normally recommended dosage level as in refinery overhead systems, water soluble corrosion inhibitors are more effective than hydrocarbon soluble ones in the vapour condensing region as well as in the liquid condensate of both naphtha fractions.     

Flywheel-type tensile impact tester with a new load cell for polymer sheet and film

A new load cell for flywheel-type impact tensile testing was designed and fabricated for specimens of polymer sheet and film. The cell employs a piezoelectric ceramic oscillator (toric in shape) as a load sensor, which has a high natural frequency (1800 kHz) and high sensitivity (ca. 0.1 V/N without amplification). The time constant for the electric circuit was improved substantially by the introduction of a voltage follower using an operational amplifier with excellent performance (common mode voltage ±120 V and slew rate 100 V/μsec). The positioning of the load sensor and the shape of specimen clamps are important design features, especially the halved Morse-type taper pins in the structure of the specimen clamps. Signals of impact, passing through the piezoelectric oscillator and the voltage follower, are recorded by a transient time converter. The converter is equipped with a memorization system, an automatic pretrigger circuit, and a facility for reproduction under a slow time base, thus eliminating the need for troublesome photographing. For performance testing of the impact tester, oriented poly(ethylene terephthalate) sheets were used and good results were obtained.     

变频器在热媒炉供风系统中的应用

介绍聚酯装置热媒炉供风装置及其控制系统,分析其目前存在的问题,提出了用变频器进行改造的控制方案,并且介绍变频控制系统的设计和硬件配置。     

Electrochemical generators of pulsating or alternating current

This paper concerns the design of three different electrochemical generators of nonsteady current: two generate a pulsating direct current, the third generates an irregular alternating current. The (Fe|NaBrO3(aq.)+H2SO4(aq.)|Pt) generator induces an alternating current in a secondary circuit connected to a transformer. The influence of electrode size and external resistance on current oscillation parameters and on power is shown. The shape of current oscillation in the generators (Fe|NaBrO3(aq.)+H2SO4(aq.)|Pt), (Zn/ZnSO4(aq.)||NaBrO3(aq.)+H2SO4(aq.)|Fe) and (Fe|NaBrO3(aq.) +H2SO4(aq.)|Fe) are also shown and the working of the three generators is explained.     

Ternary Logic Gates Using Quantum Dot Gate FETs (QDGFETs)

Quantum dot gate FETs (QDGFET) produce one intermediate state between two stable on and off states due to the change in the threshold voltage. A circuit model based on Berkeley Short-channel IGFET Model (BSIM) that accounts for this intermediate state is developed. Different ternary logics such as ternary logic inverter, MAX-MIN functions, multiplier, comparator, etc. can be implemented using QDGFETs. In this work the designs of ternary logic AND and OR gate based on QDGFET is introduced. Increased number of states in three state QDGFETs will increase the number of bit handling capability of this device and will help to handle more bits at a time with less circuit elements.     

三段串联绝热轴向氨合成塔的模拟计算和设计优化

提出三段轴向氨合成反应器的数学模型和设计优化方法，对三段轴向氨合成反应器进行模拟计算。同时计算了操作压力分别为１５７８，１５０，１００，７．５ＭＰａ时，在三段串联绝热轴向反应器中满足日产１０００ｔ氨所需的最少催化剂用量。     

信号发生模块的Linux驱动程序设计

设计中的信号发生电路主要是由数模转换芯片DAC7725U发出模拟信号,以控制激光器按照一定规律工作。首先介绍嵌入式驱动程序的作用及模型,通过对信号发生电路原理的介绍,以基于OMAP-L137的工业控制开发板为平台,详细地阐述了基于嵌入式Linux操作系统的信号发生模块的驱动程序设计及其测试程序的编写,并实现了设计中所需的±10 V方波信号的输出,为以后更深一步地学习驱动开发奠定了基础。     

An H-shaped design for membraneless micro fuel cells

The geometry of micro fuel cell design influences the reactants’ mixing and the depletion at downstream of the channel and thus effects the cell performance. This paper proposes a design for membraneless micro fuel cells with an H-shaped cross-section and a small passage between the anode and cathode channels. The small passage restricts the mixing of the anode and cathode fluids in the main channel. Numerical simulations with electro-chemical reactions have been carried out to investigate the distribution and crossover of the reactants and also the mixing and depletion regions in the system. Results show that optimizing the size of the passage between the anode and cathode channels plays an important role in reducing the mixing of reactants and in increasing fuel utilization. The H-shaped design shows that the mixing region is reduced in size by about 20%, so the H-shaped design has 10 times less fuel crossover than the conventional rectangular design. Moreover, fuel utilization is increased by about 8% with respect to that of the conventional rectangular design. 90° angles between the passage and the anode and cathode channels provide the best layout for this H-shaped design. The aspect ratio 0.083 for the anode and cathode channels exhibits 23% higher fuel utilization than the conventional rectangular design. Moreover, the size of the passage has a significant influence on the boundary layer thickness, the depletion region and the current density. A micro fabrication of the H-shaped design was made and the open circuit voltages were measured. The results are compared with those in the available literature.     

Two novel low-power and high-speed dynamic carbon nanotube full-adder cells

In this paper, two novel low-power and high-speed carbon nanotube full-adder cells in dynamic logic style are presented. Carbon nanotube field-effect transistors (CNFETs) are efficient in designing a high performance circuit. To design our full-adder cells, CNFETs with three different threshold voltages (low threshold, normal threshold, and high threshold) are used. First design generates SUM and COUT through separate transistors, and second design is a multi-output dynamic full adder. Proposed full adders are simulated using HSPICE based on CNFET model with 0.9 V supply voltages. Simulation result shows that the proposed designs consume less power and have low power-delay product compared to other CNFET-based full-adder cells.     

功率半导体器件击穿特性及结终端结构参数研究

根据功率半导体器件(如BJT、VDMOSFET等)的结终端结构特点,利用TCAD半导体器件仿真软件全面系统的分析了结终端高浓度扩散区结深及三种不同结终端保护结构(结终端延伸结构、浮空场限环结构及结终端刻蚀结构)参数对器件击穿特性的影响.仿真结果表明:对于终端高浓度扩散区,当表面浓度一定时,随着扩散区结深的增大,器件击穿电压呈现出先增大后减小的变化特点. PN结终端柱面结边缘区域的电场局部集中是导致器件击穿电压降低的主要因素.对于三种不同的结终端保护结构,均可有效地降低柱面结边缘电场强度,显著地改善器件的反向击穿特性.对比三种结终端保护结构,结边缘刻蚀结构对器件击穿特性的改善效果较好.