Shape‐memory polyurethane/multiwalled carbon nanotube fibers

Shape‐memory polyurethane/multiwalled carbon nanotube (SMP–MWNT) composites with various multiwalled carbon nanotube (MWNT) contents were synthesized, and the corresponding SMP–MWNT fibers were prepared by melt spinning. The influence of the MWNT content on the spinnability, fracture morphology, thermal and mechanical properties, and shape‐memory behavior of the shape‐memory polymer was studied. The spinning ability of SMP–MWNTs decreased significantly with increasing MWNT content. When the MWNT content reached 8.0 wt %, the fibers could not be produced because of the poor rheological properties of the composites. The melt‐blending, extrusion, and melt‐spinning processes for the shape‐memory fiber (SMF), particularly at low MWNT contents, caused the nanotubes to distribute homogeneously and preferentially align along the drawing direction of the SMF. The crystallization in the SMF was promoted at low MWNT contents because it acted as a nucleation agent. At high MWNT contents, however, the crystallization was hindered because the movement of the polyurethane chains was restricted. The homogeneously distributed and aligned MWNTs preserved the SMF with high tenacity and initial modulus. The recovery ratio and recovery force were also improved because the MWNTs helped to store the internal elastic energy during stretching and fixing. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Thermal runaway prevention in catalytic packed bed reactor by solid temperature measurement and Control

Magnetic crystallite thermometry has been used to measure the average nickel crystallite temperature in packed bed reactors during ethane hydrogenolysis, an exothermic reaction. The technique is based on the temperature dependence of the magnetic moment of dispersed nickel catalysts. Measurement of the average catalyst temperature is very useful for reactor control because of its shorter time constant compared with exit fluid temperature. Bed temperature control based on the exit fluid temperature, which has often been used as a control variable, is too slow to protect thermal runaway of the bed. The advantage of short time constant by measuring the average catalyst temperature has been incorporated with enhanced feedback control system to control the bed temperature and prevent the thermal runaway of the catalyst bed. An enhanced feedback control structure with supervisory action performed better than the classical proportional-integral control in runaway prevention when the two control schemes were compared with each other on the basis of the trippoint (incipient thermal runaway).     

基于TCN的地铁列车控制方案的研究

本文针对地铁车厢内控制设备分散的问题,设计了基于TCNRTP的地铁列车控制网络系统。采用NS2网络模拟软件构建的虚拟网络环境,编写消息数据传输层协议,通过测试列控网络的通信效率,得出了影响通信效率的因素;通过配置列控通信设备的基本功能和设定装置运行参数达到配置网络化通信的目的。     

Application of structural curvature of coalbed floor on CBM development in the Zaoyuan block of the southern Qinshui Basin

Based on controls of structural style and the position in coalbed methane(CBM)development,we used a method of curvatures to study its relations with CBM development parameters.We calculated structural curvatures of contours of the No.3coal seam floor of the Shanxi Formation in the Zaoyuan block of the Qinshui Basin and analyzed its relations with development parameters of coalbed methane wells.The results show that structural curvature is negatively related to coal reservoir pressure,while positively related to permeability.With an increase in structural curvature,the average production of coalbed methane wells increases at first and then decreases,reaching the highest production at 0.02 m-1 of structural curvature.Therefore,structural curvature can be an important index for potential evaluation of coalbed methane development and provide a basis for siting coalbed methane wells.     

大变幅扬程多机组泵站并联运行水泵性能分析

分析了大变幅扬程下灌溉泵站并联运行水泵机组性能,提出了提高泵站装置效率的方法。     

Highly ion-conductive solid polymer electrolytes based on polyethylene non-woven matrix

Highly ion-conductive solid polymer electrolyte (SPE) based on polyethylene (PE) non-woven matrix is prepared by filling poly(ethylene glycol) (PEG)-based crosslinked electrolyte inside the pores of the non-woven matrix. The PE non-woven matrix not only shows good mechanical strength for SPE to be a free-standing film, but also has very porous structure for high ion conductivity. The ion conductivity of SPE based on PE non-woven matrix can be enhanced by adding sufficient non-volatile plasticizer such as poly(ethylene glycol) dimethyl ether (PEGDME) into ion conduction phase without sacrificing mechanical strength. SPE with 20 wt.% crosslinking agent and 80 wt.% non-volatile plasticizer shows 3.1 × 10⁻⁴ S cm⁻¹ at room temperature (20 °C), to our knowledge, which is the highest level for SPEs. It is also electrochemically stable up to 5.2 V and has high transference number about 0.52 due to the introduction of anion receptor as an additive. The interfacial resistance between Li electrode and SPE is low enough to perform charge/discharge test of unit cell consisting of LiCoO₂/SPE/Li at room temperature. The discharge capacity of the unit cell shows 87% of theoretical value with 86% Coulombic efficiency.     

Effects of silicone oil and polymeric modifiers on the mechanical properties of highly filled LLDPE

The effects of coupling agents, silicone oil, and three types of polymeric modifiers on the mechanical properties of linear low density polyethylene (LLDPE) composites highly filled with aluminium hydroxide [Al(OH)₃] were studied. Polymeric modifiers that contain polar groups, such as silane‐grafted polyethylene (Si‐g‐PE) and acrylic‐acid‐grafted ethylene‐vinyl acetate copolymer (AA‐g‐EVA), improve the mechanical properties dramatically, while nonpolar modifiers improve them to some extent. When Al(OH)₃ was treated using a titanate coupling agent, the silicone oil increased the impact strength and elongation at break of the LLDPE/Al(OH)₃ composites. Introduction of a polymeric modifier containing polar groups destroys the beneficial effects of silicone oil on film mechanical properties, while the introduction of a nonpolar elastomeric polymeric modifier retains the high impact strength and elongation at break. SEM analyses provide the indirect evidence of the encapsulation of silicone oil around the filler. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 121–128, 2002     

Study of UAV tracking based on CNN in noisy environment

Multimedia Tools and Applications - Recently, there are lots of tracking methods proposed to improve the performance of visual tracking in videos with challenging situations, such as background...     

Robust Control of Networked System and Its Application

International Journal of Control, Automation and Systems - In this paper, the stability issue of networked system with dynamical topology in intelligent vehicle is studied. The systems are...