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31.
Siddhant Naudiyal Martha Briceno de Gutierrez Richard Greenwood Paul Bowen Mark Simmons Stuart Blackburn Hugh Stitt Darren Gobby Aswani Mogalicherla 《Advanced Engineering Materials》2023,25(16):2201766
Manufacturing honeycomb-structured catalysts require a careful understanding of the microstructure of the solid substrate and its dependence on thermal-processing conditions. Herein, it is the thermal responses of microcracks in an uncoated microcracked aluminum titanate honeycomb catalyst is investigated by analyzing the material's resonance frequency using the high-temperature impulse excitation technique. The resonance frequencies are presented as Young's modulus values to avoid sample size effects. Dynamic Young's modulus measurements show closed-loop hysteresis due to microcracks healing and reopening, causing a reversible response. The hysteresis is further used to understand microcracks’ dependence on critical thermal-processing conditions used in a catalyst manufacturing plant, including peak operating temperature (800–1000 °C), dwell period (1–3 h), and heating rates (1–5 °C min−1). Microcracks are observed to have two healing responses: instantaneous and delayed healing. Both responses significantly influence the design of catalyst manufacturing. Complete reopening of microcracks from their healing temperature (1150 °C) is a very time-consuming process (50–60 h). However, it is shown in the analysis that microcrack relaxation is a critical phenomenon that must be considered in quality-controlled environments. 相似文献
32.
Mercer Eric Slind Konrad Amundson Isaac Cofer Darren Babar Junaid Hardin David 《Software and Systems Modeling》2023,22(5):1451-1471
Software and Systems Modeling - Safety-critical systems such as avionics need to be engineered to be cyber resilient meaning that systems are able to detect and recover from attacks or safely... 相似文献
33.
Darren Brown Rehan Sadiq Kasun Hewage 《Clean Technologies and Environmental Policy》2014,16(6):1119-1131
Air emissions generated in grey cement manufacturing originate primarily from the combustion of fossil fuels required to heat the kiln and the chemical reaction of raw materials in the pyroprocessing phase. Given that the kiln system is enclosed, air emissions generated, discharge from a single point source kiln stack. Unlike other industries, the point source kiln stack enables the cement sector to accurately monitor and record total air emissions. The largest contributors to air emissions from grey cement manufacturing are carbon dioxide (CO2), oxides of nitrogen (NO x ), sulphur dioxide (SO2) and dust/particulate matter (PM). In Canada, grey cement manufacturing facilities are required to annually report these emissions through the National Pollutant Release Inventory (NPRI). Since CO2, NO x , SO2 and PM are the largest contributors to air emissions, and Canadian grey cement facilities are required to report these emissions, combining NPRI data with annual grey cement production data allows for the development of intensity-based environmental performance indicators. Based on data provided by NPRI, in combination with industry production, we can better understand the environmental performance of Canada’s grey cement manufacturing. On the global stage, intensity-based performance measures provide a useful tool for comparison and demonstrate a strong environmental performance for grey cement production in Canada. As an energy intensive and trade exposed (EITE) grey cement manufacturing is vulnerable to unbalanced environmental policy, which may ultimately result in leakage of production and air emissions to developing countries. 相似文献
34.
Creek DJ Jankevics A Breitling R Watson DG Barrett MP Burgess KE 《Analytical chemistry》2011,83(22):8703-8710
Metabolomics is an emerging field of postgenomic biology concerned with comprehensive analysis of small molecules in biological systems. However, difficulties associated with the identification of detected metabolites currently limit its application. Here we demonstrate that a retention time prediction model can improve metabolite identification on a hydrophilic interaction chromatography (HILIC)-high-resolution mass spectrometry metabolomics platform. A quantitative structure retention relationship (QSRR) model, incorporating six physicochemical variables in a multiple-linear regression based on 120 authentic standard metabolites, shows good predictive ability for retention times of a range of metabolites (cross-validated R(2) = 0.82 and mean squared error = 0.14). The predicted retention times improved metabolite identification by removing 40% of the false identifications that occurred with identification by accurate mass alone. The importance of this procedure was demonstrated by putative identification of 690 metabolites in extracts of the protozoan parasite Trypanosoma brucei, thus allowing identified metabolites to be mapped onto an organism-wide metabolic network, providing opportunities for future studies of cellular metabolism from a global systems biology perspective. 相似文献
35.
Objective: To examine the effectiveness of 2 condom promotion videotapes on self-efficacy, intentions, and behavior. Design: Two hundred twenty college students completed social-cognitive and behavioral measures and were then randomly assigned to receive one of two 30-min condom promotion videotapes (male or female student presenters) or to a wait-list control condition. Participants who watched 1 of the videotapes completed immediate posttest measures, and 85% of participants completed a 4-month follow-up. Main Outcome Measures: Self-efficacy for condom use, intentions to use condoms, use of condom during last sex, and consistent condom use over the last month. Results: Participants who received either video reported greater self-efficacy to refuse to have unprotected sex and intentions than controls at follow-up. Individuals who received either video were more likely than controls to report using a condom during last sex with a regular partner, and those who watched the female presenter were more likely to report consistent condom use. Conclusion: Participants benefited in terms of self-efficacy and intentions from receiving either video, but both men and women benefited more in terms of condom use behavior from receiving the female video. Future research is needed to determine whether opposite-sex speaker videos could be beneficial with a larger (and more sexually active) sample and whether these effects are maintained over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
Physiochemical data were obtained for five iron tubercles from a single drinking water distribution system (DS). Texturally, there were two groups based on internal morphology: one with a core of soft brownish material marbled with veins of a hard black material, the other has a core consisting mostly of the hard, black material. Three iron mineral phases occur, α-FeOOH, γ-FeOOH, or Fe3O4. All three coexist in each tubercle but in widely varying proportions. These iron pipe tubercles exhibit a greater diversity within a single DS than previously thought. Because the chemical conditions for the formation of each material is different, water quality parameters may not be the main control of tubercle formation and growth. 相似文献
37.
This paper details the initial development of a method for determining the associated recurring labour costs for the manufacture of a aircraft component that will form the basis for a computerised methodology for determining the optimum manufacturing method for a component design. The research focuses on the flow of process steps to manufacture an aircraft component for the vacuum-assisted resin transfer moulding and resin transfer moulding manufacturing process. The methodology developed is based on applying MIT cost equations to process steps from which cost variables and constants are established to represent an estimated costing of the aircraft structure. This research will assist in providing a swifter and more accurate conceptual design/manufacturing system that includes an analysis of cost and will assist the production of trade studies that consider the manufacture of aircraft components using cost-effective technologies, such as liquid moulding. 相似文献
38.
Highly organized cubic mesoporous TiO2 and SnO2 nanocrystalline thin films were reproducibly synthesized via an evaporation-induced self-assembly (EISA) process with a triblock copolymer (Pluronic F127) as the template, by precisely controlling the water content and chelating agent in the initial sol solution as well as by controlling the external relative humidity during the aging step. It has been found that the mesoscopic regularity of the fabricated mesoporous films critically depends on the hydrolytic reactions of inorganic precursors. That is, suppressing the hydrolysis reaction in the initial sol and providing the long-term stability for the sol in the coated film during the aging step are key factors in the formation of highly organized structure. The synthetic strategy was also extended to obtain various TiO2- and SnO2-based mixed oxide thin films with tunable composition, including WO3/TiO2, SiO2/TiO2, Nb2O5/SnO2, by selectively controlling the kinetics of hydrolytic reaction for the additional inorganic precursors. The prepared composite films were crack-free, ultra-highly transparent, and thermally stable. 相似文献
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