阻坝扩张式复合机头结构参数对短纤维补强橡胶复合材料性能的影响

研究阻坝扩张式复合机头的结构参数包括扩张比、扩张角、阻坝间隙、定型流道段长度、收敛角和过渡流道段长度对短纤维补强橡胶复合材料性能的影响。结果表明:当扩张比为5、扩张角为150°、阻坝间隙为4 mm、定型流道段长度为50 mm、收敛角为120°、过渡流道段长度为30 mm时,短纤维补强橡胶复合材料的综合物理性能较好,且各向异性明显。     

Analytical Study of Effect of Channel Doping on Threshold Voltage of Metal Gate High-k SiGe MOSFET

The paper reports the analytical model for the analysis of the effects of channel doping on the threshold voltage. A silicon germanium p-MOSFET with high-k dielectric material along with a metal gate is used for the analysis. The presented model considers the short channel effects, junction depth, doping of the layers and metal gate work function. Results are validated with the 22 nm device geometry. The MOSFET with reduced channel doping reflects the corresponding reduction in the threshold voltage. The model can effectively analyze the SiGe p-MOSFET for device designing in the nanometer regime.     

基于ID的(t,n)门限密钥分配方案

针对目前密钥分配仍需要安全信道的不足,结合基于ID下密钥产生的优点和BLS短签名方案的长处,第一次构造了一个基于ID的无需安全信道的(t,n)门限密钥分配方案,并对其代价和安全性进行了分析。该方案在电子商务等方面有着广泛的应用。     

Effect of Substrate Induced Surface Potential (SISP) on Threshold Voltage of SOI Junction-Less Field Effect Transistor (JLFET)

Silicon - In the present paper, a threshold voltage model of short channel silicon-on-insulator (SOI) Junctionless Field Effect Transistors (JLFETs) has been presented. The model includes the...     

Analysis of Temperature Effect in Quadruple Gate Nano-scale FinFET

Silicon - Quadruple gate FinFET is a promising candidate among other multi-gate MOS devices due to it’s better scalability and higher short channel effect suppression capability in advanced...     

Investigation of Quantum Confinement Effects on Molybdenum Disulfide (MoS2) Based Transistor Using Ritz Galerkin Finite Element Technique

Silicon - This paper presents the effect of quantum confinement on the potential of short channel mono-layer molybdenum disulfide (MoS2) based transistor using Ritz Galerkin finite element...     

3-D Simulation of Novel High Performance of Nano-Scale Dual Gate Fin-FET Inserting the High-K Dielectric TiO2 at 5 Nm Technology

Silicon - The evolution of integrated circuit is based on the miniaturization of dimension in the transistor Mosfet, this reduction causes the undesirable effect: short channel effects (SCE) and...     

Short-channel structured reactor: Experiments versus previous theoretical design

The study deals with the so-called short-channel structures (very short monoliths) that were introduced by Ko?odziej and ?ojewska [1] on the theoretical basis. The structures are very short so the entrance (mixing) section occupies majority of the channel length. This leads to highly enhanced heat and mass transfer, but the flow resistance is increased as well. The article presents experimental results of flow resistance, heat and mass transfer for short-channel structures of sine and triangular cross-sectional channel shape. The results presented in terms of dimensionless quantities confirmed theoretical consideration presented in [1]. The efficiencies of the structure have been derived that show the structures as more efficient when compared to classic monoliths or packed bed reactors.     

气液氯化反应填料塔的设计模型

将短湿壁管中的液膜面积和气体所通过的有效通道体积分别视作填料塔内有效传质面积和空隙体积,从短湿壁管测得的氯气与丙酮反应的气相传质关联式导出全新的且较为可靠的气液氯化反应填料塔的设计模型。其计算值与实际运行结果的最大相对误差仅为3.56%。     

短作业线直接无捻粗纱拉丝工艺研究

对短作业线(3m以下)条件下直接无捻粗纱生产工艺进行了研究探讨,从中找出了适合坩埚及通道拉丝条件下直接无捻粗纱比较合理的拉丝及烘干工艺。     

板间距对三角槽道脉动流流动阻力的影响

以水为工质对不同板间距的三角槽道脉动流流动阻力特性进行了研究。基于受力平衡方程,建立了适用于三角槽道脉动流压降的数学模型,用于理论分析流动阻力的影响因素。通过实验测试与数值模拟,校验数学模型的合理性,并且对三角槽道脉动流流动阻力进行分析。结果表明,流动阻力主要受板间距、涡旋拟“能”两方面因素影响,且与板间距呈反比,与涡旋拟“能”呈正比;板间距的缩小,会使流动阻力增加,当缩小到板间距与槽深比值为1.0时,出现流动阻力的阶越式增长,上升1个数量级;造成流动阻力骤升的主要原因在于：随着板间距的缩小,流场结构逐渐变化,三角槽道内涡旋的影响区域由“三角槽内部”逐渐转变为“整个流道”,且主流区壁面出现流动分离,出现涡旋流动与波状流共存现象,使流动阻力大幅提升。     

工艺参数对水辅助熔体充模流动的影响

基于水辅助注塑仿真模具,采用示踪技术,对不同注水延迟时间、注水压力、熔体温度和熔体填充量下的水辅助充模的熔体流痕进行了考察,研究了工艺参数对熔体流动的影响.实验结果表明:随着注水延迟时间的增加,一次穿透中的回流区域呈向水道边靠近的趋势,随水流动的熔体减少,受强剪切作用的熔体区域在水道边变窄.熔体温度低,模壁附近的高黏度...     

The Flow Simulation and Experimental Study of Low-Specific-Speed High-Speed Complex Centrifugal Impellers

1 INTRODUCTION Low-specific-speed high-speed centrifugal pumps are widely used in petrochemical, aerospace and chemical industries to deliver low flow rate and high-head liquids, but there exist many problems to be solved, such as low efficiency due to disc loss and low flow rate instability due to positive slope of head-capacity characteristic curve. Through the ex- perimental study on the low-specific-speed high-speed centrifugal pumps, it is found that complex impeller with long, mid an…     

低比转速高速复合离心叶轮的流动模拟和试验研究

Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three-dimensional turbulent flow in four low-specific-speed centrifugal impellers are simulated numerically and analyzed. The relative velocity distribution, pressure distribution and static pressure rise at the design point are obtained for the regular impeller with only long blades and three complex impellers with long, mid or short blades. It is found that the back flow region between long-blade pressure side and mid-blade suction side is diminished and is pushed to pressure side of short blades near the outlet of impeller at suction side by the introduction of mid, short blades, and the size of back flow becomes smaller in a multi-blade complex impeller. And the pressure rises uniformly from inlet to outlet in all the impellers. The simulated results show that the complex impeller with long, mid and short blades can improve the velocity distribution and reduce the back flow in the impeller channel. The experimental results show that the back flow in the impeller has an important influence on the performance of pump and a more-blade complex impeller with long, mid and short blades can effectively solve low flow rate instability of the low-specific-speed centrifugal pump.     

Flow and diffusion of particles in a channel with one porous wall: Polarization chromatography

An analysis is made of the behaviour of a suspension of particles in flow in a rectangular channel with one porous wall, which is the configuration used in a technique for particle chromatography and for cross-flow filtration. General expressions are established for the axial and transversal velocity profiles which reduce to previously published simplified relationships when the channel is short and the membrane permeability is low. An asymptotic solution is given for the diffusion convection equation in this system. Experimental results for the chromatographic separation of latex particles and dextran macromolecules show that the diffusion regime is attained at low flow rates. At higher flow rates the experimental results correspond to a convection regime and at intermediate flow rates we obtain a double peak responses corresponding to both regimes.     

Approximate prediction of gas core geometry in gas assisted injection molding using a short cut method

A relatively cheap, short cut method for prediction of the form and location of the gas core, and the residual plastic wall thickness in gas assisted injection molding (GAIM) is described. The basis is a steady state, single phase solution for flow of the polymer melt through the channel of interest, without the need to model the gas penetration. The gas‐polymer interface position is predicted by an appropriately chosen isovel of the flow. For a prismatic or slowly varying channel, only a two‐dimensional developed flow solution is required. For more sharply varying cross sections, and where bends are present, a steady three‐dimensional (3D) solution is necessary. When a gas delay is used, during which polymer cools to the cavity walls, a solution for transient conduction in the static melt is carried out before the flow solution. By comparisons with the results of full 3D, transient, two‐phase simulations of GAIM, and with experimental results, the short cut method is shown to provide reasonable approximations, and in contrast to other currently used approximate methods, captures thickness variations around the circumference of noncircular channels. The asymmetric gas core location in bends is reproduced, as is the increased plastic wall thickness resulting from cooling during a gas delay. While the full analysis will still be required for complex parts and when high accuracy is required, the described short cut method is likely to prove useful in many other cases. POLYM. ENG. SCI., 47:713–720, 2007. © 2007 Society of Plastics Engineers.     

Experimental characterization of a short electrical mobility spectrometer for aerosol size classification

A prototype of a short column electrical mobility spectrometer (EMS) for size measurement of aerosol particle was design, constructed, and experimentally characterized. The short EMS consists of a particle charger, a size classifier column, and a multi-channel electrometer. Its particle size resolution is derived from a 10 channel electrometer detector. The short EMS is capable of size measurements in the range between 10 nm to 1,000 nm with a time response of about 50 s for full up and down scan. Particle number concentration in which the short EMS can measure ranges from 10¹¹ to 10¹³ particles/m³. The operating flow rate of the short EMS is set for the aerosol flow rate of 1.0–2.0 l/min and the sheath air flow rate fixed at 10.0 l/min. The inner electrode voltage of the classifier can be varied between 500–3,000 VDC. The short EMS operates at sub-atmospheric pressure, typically at 526 mbar. Validation of the short EMS performance was performed against a scanning electron microscope (SEM). Good agreements were obtained from comparison between sizes determined from the short EMS classifier and the SEM analysis. Signal current from the detector was also analyzed to give rise to number concentration of particles. Experimental results obtained appeared to agree well with the theoretical predictions.     

High-Resolution Analysis of Particle Deposition and Resuspension in Turbulent Channel Flow

Particle deposition and resuspension during turbulent flow were investigated using a rectangular channel with glass side walls. Micrometer-sized alumina particles were used in the experiments. Particle behavior in the rectangular channel was observed through a high-speed microscope camera with a resolution of 0.3 μm and a speed of 87,600 fps, and particle deposition and resuspension fluxes were quantified using digital image analysis. The experimental results showed that particle resuspension was caused by the collision of airborne particles with those deposited on the surface. The resuspension flux was found to be correlated with the deposition flux. Furthermore, the average residence time between particle deposition and resuspension was several tens of milliseconds, which was very short but much longer than the contact time at the collision. Additionally, the residence time decreased as the particle diameter increased.

Copyright 2015 American Association for Aerosol Research     

Experimental characterization of the alignment of short fibers during flow

An experimental approach has been made to investigate and characterize the alignment of short fibers contained in a suspension, during flow of the suspension through a convergent channel. Flow patterns have been obtained and analyzed for suspensions of various fiber concentrations. The influence of parameters such as fiber length, volume fraction and viscosity of the carrier medium on the degree of fiber alignment, has been examined. In order to minimize jamming, the viscosity of the carrier medium must be larger than a certain critical viscosity that is dependent on fiber length and volume fraction.     

The study of short-shot water-assisted injection molding of short glass fiber reinforced polypropylene

water penetration length and fiber orientation (along the melt flow direction) are important indicators for water-assisted injection molding products of the fiber-reinforced polymer. The effects of melt short shot size, water injection delay time and water injection pressure on these two important indexes are analyzed theoretically and experimentally. The study found that with the increase of the melt short shot size, the extension of the water injection delay time and the increase of the water injection pressure, the water penetration length changed from 216 to 96 mm, 170 to 210 mm, and 215 to 180 mm, respectively. Therefore, it can be known that melt short shot size has the greatest influence on water penetration length, followed by water injection delay time, and finally water injection pressure. Meantime, due to the fiber orientation and change degree of water-assisted injection-molded products along the melt flow direction, the fiber orientation in the water channel layer along the melt flow direction has the highest and lowest change degree, followed by the wall layer and finally the core layer. It can be known that the melt short shot size has the greatest influence on the fiber orientation and the degree of change along the melt flow direction, followed by the water injection delay time, and finally the water injection pressure.