Nagisa桥的施工及实桥荷载试验——PC斜拉桥与钢悬索桥的混合构造

Nagisa桥是世界上首次应用预应力混凝上斜拉桥与钢筋箱梁悬索桥组合结构的混合式PC斜拉桥，本文介绍其施工方法及完桥荷载实验情况。     

Static behaviour of a steel-concrete composite beam with an innovative horizontal connection

A new connection device, based on horizontal shear connectors and avoiding welding, has been studied through a steel-concrete composite beam subjected to a static bending test. Experimental results show a behaviour similar to steel-concrete composite beams with classical connectors: elastic and yield domains, great ductility, flexural failure mode (plastic hinge), low relative movements at steel-concrete interface. Consequently, this study allows to validate the proposed connection device under static loading and shows that it suits structural modern codes requirements.     

Imaging cells on polymer spherulites

Polymers are commonly used to construct tissue‐engineered medical products and the conditions used to process these polymeric materials can affect their biological performance. For semi‐crystalline polymers, thermal processing conditions can induce crystallization of the polymer chains into spherulites, which cause the polymer surface to become roughened. This change in surface topology can influence cell behaviours such as adhesion, morphology and proliferation. Herein, a simple microscope technique is presented, which combines fluorescence microscopy with transmitted white light microscopy using crossed polarizers. This technique allows simultaneous imaging of cells and polymer spherulites, which enables the biomaterials researcher to observe the effects of spherulites on cell alignment and morphology.     

Polyharmonic (thin-plate) splines in the analysis of composite plates

In the present study a layerwise theory for composite and sandwich laminated plates is discretized by polyharmonic (thin-plates) splines. A composite and a sandwich plate examples are presented and discussed. The combination of adequate shear deformation theory and thin-plate splines allows a very accurate prediction of displacements and stresses.     

Squeezing Molecularly Thin Alkane Lubrication Films: Layering Transitions and Wear

The properties of alkane lubricants confined between two approaching solids are investigated by a model that accounts for the curvature and the elastic properties of the solid surfaces. We consider linear alkane molecules of different chain lengths, C₃H₈, C₄H₁₀, C₈H₁₈, C₉H₂₀, C₁₀H₂₂, C₁₂H₂₆, and C₁₄H₃₀ confined between smooth gold surfaces. We observe well-defined molecular layers develop in the lubricant film when the width of the film is of the order of a few atomic diameters. An external squeezing-pressure induces discontinuous changes in the number n of lubricant layers. We find that with increasing alkane chain length, the transition from n to n - 1 layers occurs at higher pressure, as expected based on the increasing wettability with increasing chain length. We obtain good correlation between our theoretical results and wear experiments.     

超薄覆层/基层复合结构界面联接特性低频超声多导波估计方

文章提出低频超低多导波方法估计超薄覆层／基层层状复合结构界面联接特性．文中分析了超薄覆层／基层界面处于刚性联接、滑移联接和完全脱层三种情况下多种超声导波的分散特性,提出了以色散曲线为依据的低频超声多波导界面特性估计方法,进一步分析了影响方法估计准确性的各种因素。结合超声泄露导波频域分析方法,文章采用超声耦合剂耦合方式和一对中心频率为２ＭＨｚ的宽带纵波换能器,获取了ｈ〈０．１λ,具有不同界面联接特性     

An investigation into the surface fatigue of materials and thin layers using a sliding diamond spherical segment

Methods for testing the surface fatigue of materials or thin layers normally involve configurations with two or more rolling balls or discs. Such equipment and test specimens are quite complicated, and for a large number of experiments, costly. Testing could be considerably simplified if the stressing of the material surface were performed with a sliding natural diamond spherical segment. A diamond on steel (or any different material) friction pair has the particular attribute that sliding wear is absent. Under these circumstances, after a certain number of strain cycles, fatigue failure of the investigated surface or layers appears. A particularly relevant application is investigation of the adhesion of a DLC layer.     

Oxygen microprofiles of trickling filter biofilms

Oxygen microprofiles of photosynthetic and non-photosynthetic biofilms of trickling filters from a sewage treatment plant were studied with Clark type oxygen microelectrodes. The oxygen profiles in photosynthetic biofilms exhibited pronounced changes with changing light conditions, and the profiles of both types of biofilm were affected by addition of nutrients. The existence of a 100–500 μm thick diffusive boundary layer in the water just above the biofilm was evident from all recordings. The O₂ gradient in this boundary layer was used to calculate diffusive fluxes of oxygen exchanged between the biofilms and the overlying water phase. The calculated fluxes were compared to the overall oxygen consumption rates measured experimentally and to the photosynthetic activity as measured with the microelectrodes. Approximately 60–70% of the oxygen produced in the algal films during photosynthesis was consumed within the films. At least one third of this consumption may be due to photorespiration. Dark/light and light/dark shifts demonstrated a very dynamic nature of the O₂ status of the algal films, showing an increase from anaerobic conditions to 500% air saturation and vice versa within 25 min. In the same regime, pH profiles showed a similar dynamic change, whereby pH varied between 8.1 and 9.7 in the same period.

The data obtained with the non-photosynthetic biofilms show that the oxygen respiration and oxygen penetration are mostly limited by diffusive oxygen transport through the boundary layer. The overall oxygen consumption of the heterotrophic biofilms equalled within ± 10% the estimates made from flux calculations.     

双薄壁高墩大跨连续刚构桥抗风稳定性分析

以稳定基本理论为基础,利用空间有限元法对某特大桥的抗风稳定性进行了非线性计算分析,同时验证了该特大桥抗风稳定性能满足要求,分析结果为该类桥的抗风稳定性分析提供了参考。     

新型复合锚固类结构静力弱化效应试验研究

为研究新型复合锚同类结构的弱化机理及其在静载作用下的特性,进行了静力三轴试验研究。研究表明：①弱化试件同非弱化试件相比,其平均变形量为后者的2.7倍,最大为7.3倍,其平均承载力为后者的1.8倍,最大为3.2倍;②在非弱化试件中的锚杆已达到很高应变状态或试件已产生极限破坏条件下,弱化试件中的锚杆尚处于很低应变状态;③弱化试件荷载～应变关系曲线中的“峡谷”现象是弱化孔间的孔壁介质由于应力集中而出现超载破坏,引起试件产生相对卸载的结果,而多次“峡谷”现象的发生,实质上反映了孔壁介质从破裂、破碎到压实的全过程效应;④复合锚同类结构的弱化效应非常显著,其间存在极大潜能,充分利用这一潜能,将具有巨大的社会、经济和军事效益。