Publications

To satisfy future pipeline gas requirements, considerable process development work is being aimed at gasifying coal to produce substitute natural gas (SNG). The heart of many of the gasification processes being developed is a fluid-bed gasifier in which char is reacted with steam/oxygen or hydrogen. In the HYDRANE process, being developed at the U.S. Bureau of Mines, Pittsburgh Energy Research Center, char is reacted directly with hydrogen in the fluid-bed stage of the hydrogasifier. In order to scale-up the fluid-bed reactor to pilot plant or commercial size with confidence, a fluid-bed reactor model has been developed using the bubble-assemblage concept and has been shown to fit existing data reasonably well. Data from moving-bed reactor experiments and the corresponding model were compared to the fluid-bed results and illustrate the differences between plug-flow and well-mixed solid-gas reactors.

The paper reports details of a fairly simple theoretical model for estimating the flexural ultimate load of reinforced concrete beam under two-point loading in which the main reinforcement over part of the span is fully exposed in a symmetrical fashion about the mid-span in the course of the patch repair process prior to the application of the repair materials. Encouraging correlations have been found between the theoretical predictions and large-scale experimental data reported by others, which covered a wide range of design parameters. Theoretical numerical results throw some light on the perhaps initially puzzling experimental observations reported previously that the ultimate loads of beams with exposed reinforcement can increase significantly if nominal top steel (in the form of, for example, 2 × 6 mm dia. bars), such as is invariably used for holding stirrups in place, is used. Numerical results are presented that show the influence of various parameters (concrete cube strength, length of exposed main reinforcement, depth of removal of concrete, etc.) on the ultimate loud-bearing capacity of beams with exposed main reinforcement.

Carbon fiber reinforced polymer–steel structural bonded joints are often subject to mixed-mode loading i.e. coupling action of normal and shear stress occurs in the joints. In this paper, an experimental approach based on fracture mechanics was adopted to obtain the fracture toughness (G ΙC and G ΙΙC ) of an adhesive currently employed in civil engineering applications, with the corresponding pure cohesive models verified by numerical results. Furthermore, feasibility of the mixed-mode cohesive model for the current adhesive was validated through comparison of numerical and experimental results of carbon fiber reinforced polymer–steel single-lap joints. Finally, based on the validated mixed-mode cohesive model, the interfacial damage of carbon fiber reinforced polymer–steel beam joints was analyzed using the finite element method, accounting for the long-term degradation that can occur in the joint materials i.e. carbon fiber reinforced polymer and adhesive. The work in this paper can provide some useful data such as the fracture properties of the adhesive and shed some light on the design optimization of carbon fiber reinforced polymer–steel structure joints as well as the estimation of its long-term interfacial behavior when in service in civil engineering applications.

filtration and centrifugation was examined and the economics of the separation has been analyzed in detail for the COED, SRC, and Synthoil processes. In the SRC process the ash separation represented a major portion of the overall fixed capital investment ranging from 23 to 50% for the SRC process. (auth)

The use of optic measurements such as digital image correlation to take strain measurements of fibre-reinforced polymers bonded to a substrate has been on the increase recently. This technique has proven to be useful to fully characterize the bond behaviour between two materials. Although modern digital cameras can take high-definition photos, this task is far from simple due to the tiny displacements that need to be measured. Consequently, digital image correlation measurements lead to relative errors that, at an initial stage of the debonding process, are higher than those calculated close to the debonding of the fibre-reinforced polymer from the substrate. This study aims to evaluate and analyse the use of the digital image correlation technique on the bond between carbon fibre-reinforced polymer laminates and timber when subjected to a pull-out load consistent with fracture Mode II. To allow the quantification of the relative errors obtained from the digital image correlation measurements during the full debonding process, several strain gauges were used to measure the strains in the carbon fibre-reinforced polymer composite. The accuracy of the digital image correlation measurements is analysed by comparing it with those obtained from the strain gauges, which is a very well-established measuring technique. Another contribution of this study is to check the versatility of the digital image correlation measurements on a broader range of situations. To that end, several timber prisms were bonded with seven different bonding techniques with and without the installation of a mechanical anchorage at the carbon fibre-reinforced polymer unpulled end. The results showed that the digital image correlation technique was able to track the slips calculated from the strain gauge measurements until the debonding load, but after that, some difficulties to measure the displacements of the anchored carbon fibre-reinforced polymer-to-timber joints were detected. The digital image correlation technique also over predicted bond stresses when compared with those taken from the strain gauges, which led to bond–slip relationships with higher bond stresses.