Integral approach and numerical improvement to calculate the carbon concentration profiles in carburising process

In the present work, the carbon diffusion in steel, where the carbon diffusivity varies with the carbon content, was solved with the integral methods under the third boundary condition. The variation of carbon diffusivity in steel with the carbon content was described with two different functions ie. linear dependence and exponential dependence. The integral approximation for both cases was improved with the numerical computation to more accurately predict the carbon profiles. The integral solution is more accurate than the formulation based on the assumption of a constant diffusivity or those based on the assumption of a constant diffusivity and/or constant carbon content at part surface. It is also more easily used in practice than the numerical method to describe the carburising process and predict the carbon content at steel surface and carbon profiles in treated layer.

Catalytic properties of nanofibrous carbon in selective oxidation of hydrogen sulphide

Nanofibrous carbonaceous materials (NFC) as a new class of materials having many applications, can catalyze the selective oxidation of H2S to sulfur. The correlation between NFC structure and its activity and selectivity in H2S oxidation was determined. It is demonstrated that selectivity can be improved if NFC with more ordered structure be synthesized and the portion of the original catalyst in carbon be reduced by increasing the carbon accumulated in the catalyst.

Regulatory challenges in the move to a low-carbon environment

An outcome of the international climate conference in Copenhagen (COP 15, 2009) was that a number of governments have undertaken to reduce their nations' greenhouse gas (GHG) emissions and some have provided targets and deadlines for the achievement of their stated goals. While the transition to a low-carbon environment has the potential to stimulate growth, create jobs and opportunities, and to bring benefits to the economy, there are many challenges in the process. This is an exploratory paper aimed at identifying the major regulatory and governance issues associated with the move to a low-carbon environment. In terms of business governance, CEOs and other executives responsible for corporate oversight will need to monitor, assess, and manage compliance with climate change and carbon-related regulation. In the transition period government regulation encouraging appropriate carbon costs classification and measurement, financial sustainability reporting and disclosure, and responsible carbon citizenship are expected to be predominant.

Integral approach and numerical improvement to calculate carbon concentration profiles in carburising

The carbon diffusion in steel, where the carbon diffusivity varies with the carbon content, was solved with the integral methods under the third boundary condition. The variation of carbon diffusivity in steel with the carbon content was described with two different functions, linear dependence and exponential dependence. The integral approximation for both cases was improved with the numerical computation to more accurately predict the carbon profiles. The integral solution is more accurate than the formulation based on the assumption of a constant diffusivity or those based on the assumption of a constant diffusivity and/or constant carbon content at part surface. It is also more easily used in practice than the numerical method to describe the carburising process and predict the carbon content at steel surface and carbon profiles in treated layer.

Is there more soil carbon under nitrogen-fixing trees than under non-nitrogen-fixing trees in mixed-species restoration plantings?

Afforestation of agricultural land provides an important opportunity to mitigate climate change by storing carbon (C) in both plant biomass and the soil. Here we present results of a study in which we sought to determine whether soil under nitrogen(N)-fixing trees contained more C than soil under non-N-fixing trees in mixed-species plantings, and thus if inclusion of N-fixers is beneficial in terms of increasing soil C sequestration. Soils were sampled directly beneath N-fixing and non-N-fixing tree species in riparian and upland mixed-species plantings in southeastern Australia. Soil C and N contents were assessed at both the landscape and individual planting scales. At the landscape scale, there were higher levels of soil C and N under N-fixing trees compared with non-N-fixing trees. At the individual planting scale, the patterns were less clear with both large increases and decreases occurring across the range of sites. The results presented here indicate that the inclusion of N-fixers may help to increase soil C, and N, but that the response may be site- and species-specific. © 2014 Elsevier B.V.

Variability of sedimentary organic carbon in patchy seagrass landscapes

Seagrass ecosystems, considered among the most efficient carbon sinks worldwide, encompass a wide variety of spatial configurations in the coastal landscape. Here we evaluated the influence of the spatial configuration of seagrass meadows at small scales (metres) on carbon storage in seagrass sediments. We intensively sampled carbon stocks and other geochemical properties (δ(13)C, particle size, depositional fluxes) across seagrass-sand edges in a Zostera muelleri patchy seagrass landscape. Carbon stocks were significantly higher (ca. 20%) inside seagrass patches than at seagrass-sand edges and bare sediments. Deposition was similar among all positions and most of the carbon was from allochthonous sources. Patch level attributes (e.g. edge distance) represent important determinants of the spatial heterogeneity of carbon stocks within seagrass ecosystems. Our findings indicate that carbon stocks of seagrass areas have likely been overestimated by not considering the influence of meadow landscapes, and have important relevance for the design of seagrass carbon stock assessments.

Carbon productivity: a case study in the Australian construction industry

Climate change is a severe threat to human development. Environmental protection and economic growth are two significant dimensions of promoting sustainable global development. In this research, a two-step procedure has been applied to investigate carbon productivity, which is deemed an appropriate indicator to measure sustainable development in conjunction with carbon reduction and production advancement. A decomposition method with the Log Mean Divisia Index has been applied to explore the factors influencing carbon productivity change, including technological innovation and regional adjustment. The carbon productivity of the Australian construction industry from 1990 to 2012 was then investigated. Research results indicate that carbon productivity in Australian construction had increased significantly and could be further improved. Technological innovation has played an important role in promoting carbon productivity, while regional adjustment has remained roughly steady. Based on correlation analyses, scale of the construction market and stock of machinery and equipment had shown weak correlations with carbon productivity changes, and it was clear that improvement in carbon productivity could benefit capital productivity and investment return. The research has systematically defined carbon productivity and for the first time measured it for the construction industry. The results are expected to assist construction industries worldwide to investigate productivity performance and to identify the influencing factors for improving development sustainability.