Remote flood monitoring system based on plastic optical fibres and wireless motes

This paper summarises an effort in the development of a remote flood monitoring system based on plastic optical fibre (POF) sensors and a wireless mote network. The wireless mote, comprising of a network of MICA2DOT™ units, was used as a platform to monitor and record the signal from the POF sensors and transmit this information to a base station wirelessly. A prototype of the integrated wireless POF sensor unit has been constructed, rendering it possible to deploy the autonomous unit remotely at multiple monitoring points as required. A flood monitoring simulation was carried out in a 24 m × 10 m × 0.9 m wave basin where four of these wireless optical fibre mote sensors were used to detect the rising water level in the basin. The novelty of the work lies in the successful integration of the wireless platform to a POF-based liquid level sensor and the subsequent demonstration of the prototype of the system for the purposes of flood monitoring applications.The sensing principle of the POF sensor developed here is well-known and is based on the loss of total internal reflection of the optical signal as the sensor probe comes in contact with the liquid. Compared to optical fibre-based sensors reported previously in the literature, the probe profile used in this study differs in terms of its simplicity in design, while exhibiting an excellent signal intensity loss ratio without the need for additional attachments to the probe such as optical prisms. The tests carried out showed that the POF sensor is capable of detecting a variety of fluids. Exhibiting good signal stability, the sensor also detects the liquid level reliably when the liquid rises or falls to the predetermined level. The responsiveness of the optical fibre sensor was evaluated by simulating different rates at which the liquid rises by immersing the sensor tip into the liquid and vice-versa at various speeds ranging from 1 mm/min to 500 mm/min.     

基于偏振光的棉纤维成熟度仪系统

开发基于偏振光的棉纤维成熟度仪系统。利用单片机的集成度高、功能强、可靠性高、结构简单、应用灵活和价格低等特点,以偏振光成熟度检测原理为基础,运用单片机实现检测的自动化、智能化。通过光学电路将棉纤维成熟度以光电信号形式输出,用A/D转换通道进行模数转换,完成对成熟度各个参数的计算,与标准值比较并输出相对偏差。     

Nano-Engineered Carbon Fibre-Based Piezoelectric Smart Composites for Energy Harvesting and Self-Powered Sensing

The integration of piezoelectric materials onto carbon fiber (CF) can add energy harvesting and self-power sensing capabilities enabling great potential for “Internet of Things” (IoT) applications in motion tracking, environmental sensing, and personal portable electronics. Herein, a CF-based smart composite is developed by integrating piezoelectric poly(3,4-ethylenedioxythiophene) (PEDOT)/CuSCN-coated ZnO nanorods onto the CF surfaces with no detrimental effect on the mechanical properties of the composite, forming composites using two different polymer matrices: highly flexible polydimethylsiloxane (PDMS) and more rigid epoxy. The PDMS-coated piezoelectric smart composite can serve as an energy harvester and a self-powered sensor for detecting variations in impact acceleration with increasing output voltage from 1.4 to 7.6 V under impact acceleration from 0.1 to 0.4 m s⁻². Using epoxy as the matrix for a CF-reinforced plastic (CFRP) device with sensing and detection functions produces a voltage varying from 0.27 to 3.53 V when impacted at acceleration from 0.1 to 0.4 m s⁻², with a lower output compared to the PDMS-coated device attributed to the greater stiffness of the matrix. Finally, spatially sensitive detection is demonstrated by positioning two piezoelectric structures at different locations, which can identify the location as well as the level of the impacting force from the fabricated device.     

Fatigue behaviour and modelling of talc‐filled and short glass fibre reinforced thermoplastics,including temperature and mean stress effects

Effects of temperature and mean stress on fatigue behaviour of talc‐filled polypropylene (PP‐T) and short glass fibre reinforced polypropylene (PP‐G), polyamide‐66 (PA66), and a blend of polyphenylene ether and polystyrene (PPE/PS) were investigated. Load‐controlled fatigue tests were conducted under positive stress ratios (R = 0.1 and 0.3) and at several temperatures (T = 23, 85 and 120 °C). Larson–Miller parameter was used and a shift factor of Arrhenius type was developed to correlate fatigue data at various temperatures. Effect of mean stress on fatigue life was significant for some of the studied materials; however, for the PPE/PS blend no effect of mean stress was observed. Modified Goodman and Walker mean stress equations were evaluated for their ability to correlate mean stress data. A general fatigue life prediction model was also used to account for the effects of mean stress, temperature, anisotropy and frequency.     

碳纤复合约束阻尼结构共固化成型及其性能研究

使用共固化成型工艺制备了含碳纤复合材料约束层的轻质约束阻尼结构,采用180°剥离强度测试、振动性能测试对结构界面结合强度、减振性能进行测试,并通过扫描电镜观测试样内部界面微观形貌。结果表明,所制备碳纤复合约束阻尼结构中约束层与阻尼层界面结合紧密,剥离强度接近5 k N/m,减振量超过19d B,结构减重50%以上,具备较高的应用价值。     

连续纤维增强热塑性复合材料的制备成型技术及其应用前景

介绍了连续纤维增强热塑性复合材料（ＣＦＲＴＰ）的材料组成,综述了ＣＦＲＴＰ的主要制备技术、成型方法以及应用前景。     

Advances in the fabrication of titanium based composites

Titanium alloy metal matrix composites reinforced with silicon carbide fibre are being evaluated for a range of highly loaded aerospace applications. Although expensive, if used selectively they can have a dramatic effect on performance and weight. The SMC has one of the strongest capabilities in Europe for the development and production of titanium fibre reinforced MMCs. Consisting of the DRA Sigma silicon carbide fibre manufacturing facility, producing fibre on a commercial basis, and the manufacture of titanium alloy MMCs in commercial quantities by the foil fibre route, and at pilot scale using the alternative matrix coated fibre route. In the foil fibre route a filament winding and fugitive binder method is used to produce a range of component shapes with excellent fibre distribution and consistent properties. The matrix coated fibre process is seen to have advantages over the alternative methods and is likely to become an important manufacturing route for titanium MMCs, particularly for exotic high temperature titanium alloys and intermetallics, and for shapes such as rings, tubes and shafts. As no titanium MMCs components have yet reached full production, it is unclear which of these fabrication methods will become commercially viable, if any. But, the choice is likely to be based on cost, availability and product quality.     

分布式的附网存储系统的设计与实现

设计并实现了一种高性能的分布式附网存储系统,并详细介绍了其工作原理、设计流程和主要程序段。     

网络存储技术的探讨

本文介绍了传统的依赖服务器存储的缺陷以及网络存储的现状,对附网存储及存储局域网技术进行了论述,把二者进行了比较,并总结出了二者优势和缺点,最后介绍存储局域网和附网存储的应用。     

SMC的制造工艺及成型技术

针对SMC在汽车工业中的应用,介绍了该塑料的材料选择、制造工艺、成型技术和急需研究开发的课题。