含损伤软化材料层合板承压时的分叉分析

本文讨论了由纤维和树脂-损伤应变软化材料组成的层合板在面内受压时的压缩分叉。用有限变开理论和半解析有限元法建立了相应的分叉方程,并进行数值模拟。计算结果表明,分叉将在损伤材料的应变软化阶段发生,为剪切带形分叉,损伤材料骨有剪应变集中,而且在纤维和树脂的界面附近有较大的剪应变突变等现象。     

高含酸性气碳酸盐岩气藏流体敏感性实验研究

对川东北雷口坡组、嘉陵江组、飞仙关组、长兴组高含H，S及032的碳酸盐岩储层流体敏感性进行了实验研究，结果表明岩样速敏损害弱～强，水敏和盐敏损害中偏弱～极强，碱敏损害严重。岩石学分析揭示，川东北高含酸性气碳酸盐岩储层发育伊利石、微晶石英、白云石、方解石、硫化钙等潜在损害物质。钻井完井液侵入会破坏储层各物质间的原始动态平衡，诱发储层损害。主要损害机理为：①储层流体pH增加引起黏土矿物以及微晶石英失稳；②碱液与微晶石英、长石、白云石反应生成硅酸盐、高岭石、水镁石等新矿相；③流体矿化度改变可降低伊利石微粒间的连接力；④硫化钙水解产生OH^-，过量的OH-与Ca^2＋结合形成氢氧化钙沉淀；⑤储层含水饱和度和流体离子浓度改变，致使焦沥青脱附并在储层深部沉积；⑥硬石膏水化膨胀、分散运移。针对该气藏损害机理，可采用屏蔽暂堵技术以形成优质滤饼，有效降低储层流体敏感性损害。图5表2参10。     

龙开口水电站溢流坝段动力模型破坏试验研究

采用仿真混凝土材料研究了龙开口水电站溢流坝段在不同因素影响下的动力破坏特征,并通过对6个模型试验结果的分析探讨了溢流坝段的动力破坏机理。试验中考虑了坝体-库水的动力相互作用以及横河向地震动对大坝破坏的影响,采用规范谱波和场地谱波两种地震动激励进行模型超载破坏分析。试验结果为工程设计和评价溢流坝段的抗震性能提供依据。     

Influence of Storage Time and Temperature on Absorption of Flavor Compounds from Solutions by Plastic Packaging Materials

ABSTRACT: Linear low-density polyethylene (LLDPE), oriented polypropylene (OPP), polycarbonate (PC), polyethylene terephthalate (PET film and PET bottle), and polyethylene naphthalate (PEN) were stored in a model solution containing 10 flavor compounds at 4, 20, and 40 °C and flavor absorption by the plastic materials was followed in time. The absorption rate and/or total amount absorbed increased considerably with temperature from 4 to 40 °C. Depending on storage temperature, total flavor absorption by the polyolefins (LLDPE and OPP) was 3 to 2400 times higher than by the polyesters (PC, PET, and PEN). Therefore, in the factor of flavor absorption, polyesters are preferred over polyolefins as packaging material.     

中山包水电站钢岔管设计

中山包水电站钢岔管在天生桥二级水电站 6号压力钢管下平段分岔 ,岔管HD值达 15 40m2 ,结构体形复杂 ,采用NK HITEN780A Z35和NK HITEN6 90B高强度钢材制造安装 ,在国内水电工程中实际应用较少。文章着重介绍岔管的布置、结构分析和焊缝的无损检验要求。中山包水电站的正常发电运行 ,为 80kg/mm2 级高强钢在国内水电行业的应用提供了第 3个成功实例     

N.m.r. study of the ferroelectric phase transition in a 7030mol% copolymer of vinylidene fluoride (VF2) and trifluoroethylene (TrFE)

Nuclear magnetic resonance (n.m.r.) studies of ¹⁹F nuclei in a $\text{70}\text{30}\text{mol}\text{\%}$ random copolymer of vinylidene fluoride and trifluoroethylene were performed at 9.14 MHz and 20.0 MHz. The free induction decays (FIDs) were analysed in terms of two T₂ components attributed to the amorphous and crystalline portions of the polymer. The changes in crystallinity as well as the effects of the ferroelectric transition were observed during cycles of heating and cooling between 20°C and 140°C. The crystalline component of the FID lengthens by a factor of 2 at 100°C on heating and decreases by this factor at 60°C on cooling, thus exhibiting the thermal hysteresis of this ferroelectric transition. The spin-lattice relaxation was also investigated. From measurements at 9.14 MHz the observed longitudinal relaxation time T₁ appears to be dominated by the dynamics of the amorphous phase and exhibits no anomaly through the phase transition. However, from measurements at 20 MHz, well defined minima of T₁ were observed, which are associated with the ferroelectric transition (especially after repeated annealing of the samples). Results are discussed in terms of the crystalline phase structure, which appears dynamically disordered above the ferroelectric phase transition. An analogy is considered with the plastic phase transitions encountered in molecular crystals.     

Large-scale cooling towers as part of an efficient and cleaner energy generating technology

The present paper will outline the main aspects of the design and construction of cooling towers in Germany in the last decade. As part of electricity generating power plants, cooling towers play a significant role for the availability of reliable energy supplies, in a manner compatible with environmental requirements. They definitely belong to the largest and thinnest concrete structures at present. Because of the combined action of wind, thermal and moisture effects, special care has to be taken with regard to fatigue, cracking and corrosion to ensure an adequate level of safety and durability. Such a design strategy has been employed for the world’s tallest cooling tower at the Niederaussem power plant in Germany, with an overall height of 200 m and thickness values of 22–24 cm. Special considerations included the realistic non-axisymmetric distribution of soil characteristics, wind action due to interference effects (as determined by wind-tunnel tests), optimisation of the shell shape to improve structural and dynamic behaviour, injection of the cleaned flue-gas into the cooling tower, and the use of high-performance concrete (85 MPa) to improve shell resistance against acid attack by the cleaned flue-gas. The paper will present some results of an actual research project on this problem, which was conducted at the University of Wuppertal, to explore the use of high-performance concrete on design, stability and durability of cooling tower shells.     

掺染料激光介质的研究

以PMMA为基质，在助溶剂的作用下掺杂激光染料Rh6G制备出了塑料激光介质样品，采用YAG激光器作为泵浦源测试了塑料激光介质的发射光谱，讨论了其激光发射机理。