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An experimental study was performed to investigate the effect of seawater exposure on the mechanical behavior of concrete columns reinforced longitudinally with glass fiber reinforced polymer (CCR-GFRP) bars. Numerous salt crystals emerged and slight exfoliation was observed after the surfaces of the columns were immersed in seawater for 120 days. The CCR-GFRP failed in either the axial compressive failure or split-crack failure mode. Furthermore, the probability of split-crack failure gradually increased with the duration of seawater exposure. In general, the carrying capacity of the CCR-GFRP initially increased and then decreased as the seawater exposure progressed. The strains of the surface concrete and inner glass fiber reinforced polymer bars continuously increased, but the strain of the glass fiber reinforced polymer bars and probability of the variability of the strain were less than those of the surface concrete. In addition, the bonding between the glass fiber reinforced polymer bars and concrete gradually decreased with increasing diameter of the glass fiber reinforced polymer bars. As the exposure period increased, the bonding between the glass fiber reinforced polymer bars of the same concrete columns weakened significantly. [ABSTRACT FROM AUTHOR]

For isolated dc–dc power converters, the interwinding parasitic capacitance of the transformer is usually one of the main paths for common-mode (CM) noise. In order to simplify the CM noise analysis, this paper proposes a two-capacitor transformer winding capacitance model. The model is derived based on general conditions so it can be applied to different isolated converter topologies. A measurement technique is also proposed to obtain the lumped capacitance for the model. The CM noise models of several isolated converter topologies are analyzed with the proposed two-capacitor transformer winding capacitance model to achieve simplicity. Finally, the proposed transformer winding capacitance model and measurement technique are verified by simulations and experiments. [ABSTRACT FROM AUTHOR]

3D carbon linked by uniform sized nanospheres was successfully prepared by hydrothermal carbonization method. It is found that the increasing reaction temperature and extending reaction times have a similar effect on the morphology of the products, which could evolve from nanospheres to 3D carbon linked by nanospheres or layered structure. The final chemical structure of the products can be switched from a carbon rich in oxygen containing functional groups type to a carbon network of extensive aromatic domain. [ABSTRACT FROM AUTHOR]

The establishment, reproduction, dispersal, and distribution of alien plants are affected by various factors during the transition from being newly introduced in a habitat to being invasive. In the agro-pastoral ecotone of northern China, comprising farmlands and natural grasslands, the biological characteristics of alien plant species were the key intrinsic factors (propagation characteristics and competitive ability), followed by such extrinsic factors as human interference and environmental heterogeneity. Among biological characteristics, the life form may be an important and useful indicator of the invasive ability of a species, and the risk of invasion is greater from alien species that are poisonous, inedible, and have traits that facilitate wide dispersal. Farmlands may serve as initial shelters for alien species, from which they spread into neighbouring habitats, whereas natural grassland may act as a barrier to plant invasions. Management practices detrimental to grasslands, including overgrazing, reclamation, and road construction, often facilitate the invasions; therefore, counter measures such as reseeding and a ban on grazing need special attention. Environmental factors including precipitation, nutrients, prevailing winds, fires, and topography may be other factors that promote or block the process of invasion. In studying ways of preventing or controlling such invasions, alien plants with short life cycle, prolific seed production, and strong competitiveness, deserve particular attention and so do human activities that may damage the environment and fragile habitats. [ABSTRACT FROM AUTHOR]