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The paper proposes the novel Variable Angle Tow (VAT) placement technique to create local reinforcement on fiber reinforced composites with holes which enables to optimize the design for variable stiffness laminates by placing continuous fiber to follow the pre-calculated principle stress trajectories automatically. The potential factors influencing the strengthening effect are investigated, including reinforcement types, lay-up configurations and dimensions. The results from tensile test discusses the failure modes and reveals that with VAT reinforcement, especially the elliptical reinforcement, the ultimate strength of the open-hole specimen can be significantly improved compared with the plain cloth reinforcement. It is also found that the double-sided reinforcement configuration is superior to single-sided or interlayer configurations, and both the circular and elliptical VAT reinforcements possess their optimal dimensions when considering the weight. Subsequent Finite Element Analysis indicates the reinforcing mechanism that the stress concentration in the reinforced region is alleviated by redistributing the stress to the outer unreinforced region.

An anaerobic baffled reactor (ABR) with five compartments for treating sulfate-laden wastewater was started up and the multi-phase separation, i.e., acidogenesis, sulfidogenesis, sulfur-production and methanogenesis, was achieved in 130 days of this study. The present study assessed the variations in COD/SO 4 2− ratios as an important factor to evaluate the competition between sulfate-reducing bacteria and the other anaerobic bacteria in the phase-separation system for reactor performance stability. The experiment was divided into Phase I, II and III. In Phase I, the influent COD/SO 4 2− ratio decreased from 13.3 (4 g COD/0.3 g SO 4 2− ) to 2.0 (4 g COD/2 g SO 4 2− ) by increasing the sulfate concentration, the above phases shifted to subsequent compartments, the predominant sulfide oxidizing bacteria (SOB) and methane-producing archaea (MPA) shifted to subsequent compartments, the SOB and Methanothrix -like bacteria were coated with S particles and precipitated at a COD/SO 4 2− ratio of 2.0, resulting in an inefficient removal/yield of COD and SO 4 2− /methane, and showed the system to deteriorate. In Phase II, although the COD/SO 4 2− ratio increased to 3.0 (6 g COD/2 g SO 4 2− ) with an increase in COD concentration, the phase - separation shift to subsequent compartments did not reverse and sulfidogenesis proceeded throughout all compartments, S particles and precipitates coating on SOB and Methanothrix -like bacteria more, sulfide oxidation was inhibited and the effluent quality further deteriorated. In period III, the COD/SO 4 2− ratio further increased to 6.0 (6 g COD/1 g SO 4 2− ) with a decrease in sulfate concentration, sulfidogenesis and methanogenesis returned to the front compartments and the inhibition of sulfide oxidation was relieved, resulting in an increase in removal/yield of COD and SO 4 2− /methane and the improvement of performance. These results indicate that the influent COD/SO 4 2− ratio and substrate concentration affect the metabolic phase-separation and treatment system stability.

Liquid composite moulding (LCM) has been successfully used to manufacture natural fiber reinforced composites. Effects of liquid absorption and swelling on the permeability of natural fiber fabrics in LCM were investigated. It shows that the saturated permeability measured in the corn syrup is 23.1–69.5% smaller than that in the motor oil because of reduced porosity and flow paths caused by liquid absorption and swelling. Based on traditional models by considering the effects of liquid absorption and swelling of jute fibers, a mathematic model was developed to predict the variable permeability during the mold filling. Experimental results demonstrate excellent agreement with the prediction. The effects of flow rate and fiber volume fraction on permeability were also analyzed. It is found that liquid absorption and swelling may dominate the permeation when the flow rate is low while the flow rate may contribute more when it is large. Furthermore, fiber volume fraction is more sensitive to permeability in the syrup than is the case in the motor oil because of the absorption and swelling of natural fibers. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers