AEM对EVA电缆材料性能影响的研究

应用乙烯-丙烯酸酯橡胶(AEM)与乙烯-醋酸乙烯酯共聚物(EVA)、氢氧化镁(MH)、氢氧化铝(ATH)以及沉淀法白炭黑(SiO2)进行熔融共混复合,制备出系列EVA基电缆材料。应用扫描电镜(SEM)、差示扫描量热仪(DSC)、万能试验机和极限氧指数测试仪对EVA材料的结构和性能进行表征和测试。研究结果表明,AEM明显提高了EVA电缆材料的耐油性能,当AEM含量为3. 0%时,电缆材料综合性能优良,其LOI达到39. 3%,拉伸强度和断裂伸长率分别为11. 6 MPa和142%。     

聚丙烯纤维及废弃陶瓷对低品级菱镁矿制氯氧镁水泥性能的影响

本文以聚丙烯纤维、普通废弃陶瓷、工业氯化镁以及含39.12％活性氧化镁的低品级轻烧氧化镁制成了一种镁水泥基建筑墙体材料.采用正交试验确定了最佳配合比,并对聚丙烯纤维、废弃陶瓷复合增强剂对镁水泥干缩性能的影响进行了探讨.研究结果表明,纤维及陶瓷对镁水泥分别起到了增韧增强及骨架作用.其制品28 d干缩率仅为0.03％.     

Waste frying oil as a precursor for one-step synthesis of sulfur-doped carbon dots with pH-sensitive photoluminescence

Proper disposal of waste frying oil (WFO) is an important waste-management concern. In this paper, we develop a facile method to reuse WFO for one-step synthesis of sulfur-doped carbon dots (S-C-dots) with the assistance of concentrated sulfuric acid. The as-synthesized S-C-dots are uniform in size and show partial disordered graphite-like structure. Different from the doping-free or nitrogen-doped carbon dots, the S-C-dots perform a strong ultraviolet emission at 378 nm due to successful sulfur-doping. Noticeably, the S-C-dots exhibit a distinct pH-sensitive feature and the intensity of photoluminescence increases linearly in the pH range from 3 to 9. Furthermore, possessing fascinating optical properties, high photostability, and low cytotoxicity, the S-C-dots have served as fluorescent probes for cell imaging.     

Synthesis of carbon molecular sieve microspheres via amino phenolic resin as precursor formed from in-situ reaction composite micelles

The carbon molecular sieve microspheres (CMSm) is one kind of porous carbonaceous materials. Owing to its high surface area and stability, CMSm have been attracted immense attention in various fields. In this study, the CMSm with tunable pore structure has been synthesized via self-assembling, in-situ reaction and soft-templating method in aqueous system. Meanwhile, the influence of carbonization temperature, heating rate, surfactant content and the amount of pore-forming agent (1, 3, 5-trimethylbenzene) on the morphology and pore properties of CMSm were studied. The result of nitrogen adsorption/desorption analysis indicates that the volume of the micropores increases as carbonization temperature increases, and generally decreases as the heating rate increases. The amount of surfactant and pore-forming agent have little influence on the volume of the micropores. It is also found that the CMSm have good hydrogen storage performance.     

Energy conservation effect of new HVAC system for condominiums with solar collectors integrated with the balcony handrail

Energy consumption in Japan's houses has been increasing rapidly over the past decades. Furthermore, installation of 24-h ventilation systems in houses became mandatory last year, which will probably increase the heating, ventilation, and air conditioning (HVAC) energy consumption in Japan's houses. Regardless of these situations, natural energy utilization to reduce HVAC energy has not spread, especially in condominiums in Japan. In this study, we propose a new HVAC system for condominiums that makes use of solar heat, outdoor cool air by integrating elements in condominiums such as the balcony handrail, the 24-h ventilation system, and under-floor space. As a first step in the development of this system, we carried out experiments and computational fluid dynamics (CFD) studies on a solar heat collector integrated with the balcony handrail to determine its specification and to obtain information on its heat collection performance. As a second step, we calculated dynamic thermal load on a model condominium to evaluate the energy-saving performance and thermal comfort of the proposed system. The calculation results show that the proposed system has a high performance, both for energy saving and thermal comfort.     

Spray synthesis of monodisperse sub-micron spherical silica particles

A novel spray approach has been developed for the synthesis of controlled size oxide microparticles and the technique is illustrated by the preparation of ca. 250 nm silica particles. Stöber-type spherical silica of uniform particle size is formed by spraying a tetraethoxysilane precursor solution onto the surface of a stirred ammoniacal hydrolysis medium. Particle size characteristics are determined through selection of reaction conditions, with solvent, temperature, reagent concentrations and mixing contributing to the particle size and dispersity. The silica products have been characterized by particle size distribution measurements, electron microscopy and nitrogen adsorption studies. The mechanism of particle formation under differing experimental conditions is discussed.     

Synthesis of graphene nanoribbons with various widths and its application to thin-film transistor

Novel precursor polymers containing phenylene, naphthalene and anthracene units were synthesized for fabrication of graphene nanoribbons (GNRs) by the Suzuki coupling reaction between dibrominated monomers and diboronic ester monomers. The precursor polymers were converted into GNRs by intramolecular cyclodehydrogenation using FeCl₃ as a catalyst. The degree of cyclodehydrogenation was determined by analysis of nuclear magnetic resonance spectra. All GNR films show ambipolar charge transport behavior in thin-film transistor (TFT). The GNR film prepared from anthracene-based polymer exhibits the highest TFT performance due to its longer conjugation length and larger width of nanoribbon than GNRs prepared from phenylene and naphthalene-based polymers.     

Some considerations of the performance of small dual fuel furnaces fueled with a gaseous fuel and a liquid fuel mix containing used engine lube oil

This study is an experimental work evaluating the thermal performance of dual fuel furnaces fueled with blends of diesel and used –engine –lubrication oil (ULO), co-fired with LPG (Liquefied Petroleum Gas).ULO is regarded here to be a renewable energy source. The word “renewable” is used in the present context because waste engine lube oil will be present and will last as long as there are engines in use. The paper addresses enhancing radiation from gaseous fuel combustion such as LPG, by co-firing it with some small amounts of a lower grade liquid fuel with higher radiation propensity. The liquid fuel used is a mix of ULO and diesel. Elemental measurements conducted revealed high metals content in the used ULO, as compared with the metal content in unused fresh oil. This is believed to be the reason behind the better radiation capabilities of the flame observed when ULO is used. Results show that substituting 30% of LPG mass by a liquid fuel mixture composed (in this study) of 20% ULO and 80% diesel increases radiation to furnace walls by about 1% above the level achieved when only LPG is used with the same total equivalent amount as that of the liquid mix plus the LPG portion. 20% ULO in the liquid fuel mixture corresponds to about 6% of the total fuel mass supplied to the furnace. To highlight the role that might have been played by the excessive amounts of metals in ULO regarding radiation, runs under the same conditions have been repeated, but with fresh oil replacing ULO in the liquid mixture. The results confirmed once more the superiority of ULO when it comes to radiation enhancement. The study summarizes also some results from a previous research, conducted by the first author of the present work and co-authors, assessing used engine lube oil against waste liquid oil with biological origin namely a “used cooking oil”. This comparison further supports the use of ULO as a fuel supplement that aids heat transfer by radiation in furnaces. In addition, the study includes some measurements characterizing ULO such as viscosity at different temperatures and the calorific value. This study is believed to give useful insights for design, operation, and control in applications such as radiative boilers.     

装配式混凝土梁柱节点抗震性能试验与数值模拟

为研究不同螺栓强度等级对新型装配式半刚性混凝土梁柱节点抗震性能的影响,分别对螺栓等级为5.6级和8.8级的梁柱节点进行了足尺试验,分析了节点的滞回曲线、骨架曲线、割线刚度、等效黏滞阻尼系数等抗震性能指标,并基于ABAQUS有限元软件对现浇节点和5.6级螺栓连接的试验节点进行了数值模拟。结果表明:基于5.6级和8.8级螺栓连接的半刚性梁柱节点均具有良好的抗震性能和耗能能力,2组梁柱节点构件的刚度均随着位移等级的增加而逐渐降低,与5.6级螺栓连接的节点相比,8.8级螺栓连接的节点刚度退化速率较快,且正向加载下5.6级螺栓连接节点的极限承载力为8.8级螺栓连接节点的85.42%,负向加载下5.6级螺栓连接节点的极限承载力为8.8级螺栓连接节点的83.68%; 有限元模拟结果具有较高的准确性,能够很好地反映节点构件的抗震性能; 与现浇节点对比发现,现浇节点在耗能能力方面比试验节点好,但试验节点的极限承载力要优于现浇节点; 所得结论可为装配式半刚性梁柱结构的抗震设计提供依据,为新型装配式梁柱节点构件的发展及应用提供参考。     

基于“CDIO”工程教育模式的土木工程材料课程教学改革探索

文章探讨了“CDIO”工程教育模式在土木工程材料课程教学改革中的应用,主要是从理论知识体系模块化构建、实践技能项目驱动化构建、课程效果多功能化构建、课程考核互动后构建4个方面对土木工程材料课程教学进行改革探索,实践证明,“CDIO” 工程教育模式教学激发了学生的主动性和创造性,教学质量得到明显提高。