Engineering

Publication Search Results

Now showing 1 - 10 of 10
  • (2006) Ho, Minh; Allinson, G; Wiley, Dianne
    Journal Article
    The sequestration of CO2 as a greenhouse mitigation option is becoming an increasingly important priority for industry. Theoretically membrane based CO2 removal systems have the potential to provide a cost effective, low maintenance approach for removing CO2 from gas streams. This study examines the effect of membrane characteristics, operating parameters and system design on sequestration costs for any source-sink combination. The total sequestration cost per tonne of CO2 avoided for separation, transport and storage are compared for the separation of CO2 from a black coalfired power plant in Australia. The results show that the membranes currently available have a total sequestration cost of US$55-61/tonne CO2 avoided. Lower costs for CO2 avoided can be achieved using an MEA amine based absorption separation system. Gas separation membranes would require significant improvements in CO2 permeability and selectivity, together with reductions in the cost of membranes and changes to the process configurations and operating pressures to be competitive against MEA systems for the purposes of geo-sequestration.

  • (2006) van Glabbeek, Robert
    Journal Article
    In this paper I compare the expressive power of several models of concurrency based on their ability to represent causal dependence. To this end, I translate these models, in behaviour preserving ways, into the model of higher dimensional automata (HDA), which is the most expressive model under investigation. In particular, I propose four different translations of Petri nets, corresponding to the four different computational interpretations of nets found in the literature. I also extend various equivalence relations for concurrent systems to HDA. These include the history preserving bisimulation, which is the coarsest equivalence that fully respects branching time, causality and their interplay, as well as the ST-bisimulation, a branching time respecting equivalence that takes causality into account to the extent that it is expressible by actions overlapping in time. Through their embeddings in HDA, it is now well-defined whether members of different models of concurrency are equivalent. (c) 2006 Elsevier B.V. All rights reserved.

  • (2006) van Glabbeek, Robert
    Journal Article
    This paper raises the question on how to specify timeouts in process algebra, and finds that the basic formalisms fall short in this task.

  • (2006) Fokkink, W; van Glabbeek, Robert; de Wind, P
    Journal Article
    This paper presents a method for the decomposition of HML formulas. It can be used to decide whether a process algebra term satisfies a HML formula, by checking whether subterms satisfy certain formulas, obtained by decomposing the original formula. The method uses the structural operational semantics of the process algebra. The main contribution of this paper is the extension of an earlier decomposition method for the De Simone format from the Ph.D. thesis of Larsen in 1986, to more general formats.

  • (2006) Xu, S.; Wang, Jun
    Journal Article
    An experimental investigation of abrasive waterjet (AWJ) cutting of alumina ceramics with controlled nozzle oscillation is presented and discussed. Particular attention is paid to the effect of small oscillation angles on the various cutting performance measures. It is found that nozzle oscillation at small angles can equally improve the major cutting performance measures if the cutting parameters are correctly selected. However, under high water pressures, high nozzle traverse speeds and large oscillation frequencies, nozzle oscillation may cause a decrease in some major cutting performance measures such as surface finish. Plausible trends of cutting performance with respect to the process parameters are amply discussed. Finally, a predictive mathematical model for the depth of cut is developed and verified.

  • (2006) Kessissoglou, Nicole
    Journal Article
    This paper presents adaptive feedforward active control applied to simple structures comprised of beam, plate and cylindrical elements. For each system under consideration, by initially obtaining a good understanding of the physics of the structural and acoustic responses, the active control application can be tuned to improve the control performance. In particular, the use of active structural acoustic control to attenuate the structurally radiated sound fields is investigated.

  • (2006) Childs, Paul; Wong, Allan; Peng, Gang-Ding
    Journal Article
    The performance of a strain sensor system based on the use of carrier-modulated gratings and Fourier-domain decoding is analyzed. For three sensors, Young`s modulus is measured as 69.98 ± 0.27, 69.15 ± 0.81, and 70.65 ± 0.58 GPa. Crosstalk is shown to exist only when two sensors are designed with an overlap of the carrier band in the Fourier domain. Improving the data processing shows it is possible to limit this crosstalk to a value below that of the system error. © 2006 IEEE.

  • (2006) Wang, Yi-Ping; Wang, D. N.; Jin, Wei; Rao, Yun-Jiang; Peng, Gang-Ding
    Journal Article
    An asymmetric long period fiber grating (LPFG) with a large attenuation of -47.39 dB and a low insertion loss of 0.34 dB is fabricated by use of focused CO2 laser beam to carve periodic grooves on one side of the optical fiber. Such periodic grooves and the stretch-induced periodic microbends can effectively enhance the refractive index modulation and increase the average strain sensitivity of the resonant wavelength of the LPFG to -102.89 nm/m epsilon. The resonant wavelength and the peak attenuation of the LPFG can be tuned by similar to 12 nm and similar to 20 dB, respectively, by the application of a stretching force. (c) 2006 American Institute of Physics.

  • (2006) Wang, Jun; Liu, Hua
    Journal Article
    Predictive models for the major cutting performance measures, such as the kerf taper and depth of cut, are developed for both straight-slit cutting and profile cutting by an abrasive waterjet (AWJ). The plausibility and predictive capability of the models are assessed and verified by comparing the model predictions with the corresponding experimental data. Very good correlations between the predicted and experimental results have been found, which confirms the adequacy of the models for use in process planning.

  • (2006) Wang, Jun; Liu, Hua
    Journal Article
    An experimental investigation is presented of the various cutting performance measures, such as the kerf taper and depth of cut, in profile cutting on an 87% alumina ceramic by abrasive waterjet (AWJ) over a wide range of process parameters. It is found that the taper angles on the two kerf walls produced in cutting AWJ of profiles are different in magnitude and exhibit different trends as the profile curvature radius varies. Moreover, the depth of cut increases with an increase in the curvature radius and approaches its maximum in straight cutting. The other process variables affect the cutting process in a way similar to that in straight cutting. Recommendations are finally made for the selection of process parameters in AWJ profile-cutting of alumina ceramics. Predictive mathematical models for the major cutting performance measures that are essential for the optimization of the AWJ cutting process are reported in the subsequent part of this investigation.