Jon Powell

While self-assessment against marking criteria is widely advocated, its effects on different components of student work remain unclear. This study evaluates a redesign of a UK foundation-year engineering laboratory module incorporating a structured self-assessment coversheet and a progressive authorship scheme. Across six cohorts (n = 134), improvements concentrated in the sections that require evaluation and argument --- Discussion (d = 0.65) and Conclusions (d = 0.69) --- while procedural sections showed smaller, less consistent gains. Coding of 993 matched student--instructor section assessments for depth of engagement with criteria revealed that deeper engagement correlated with more accurate self-assessment at the between-student level, primarily in evaluative sections. However, the same section-by-section calibration was not observed within individual students, leaving the causal direction unresolved. All coding-based findings were validated through independent automated re-coding, including an intervention-blind large language model. The findings suggest that self-assessment against criteria may develop evaluative writing skills more effectively than procedural ones, though the engagement--accuracy link remains associational rather than causal at the individual level.

This study evaluates the use of cracking for the removal of carbon from fuels to be used in a power generation process. Unlike conventional power generation systems, the proposed system includes a cracking unit, the function of which is to convert primary fuels into H₂ rich syngas and solid carbon, thus avoiding the emission of CO₂ and the need for carbon capture and storage (CCS) in the power generation system. Based on the thermodynamic analysis of equilibrium reactions in the cracker, it is demonstrated that the operating temperature has a significant influence on the carbon capture rate achieved and the composition of the syngas. Carbon in the fuel can be captured in solid form from hydrocarbon fuels when operating the cracker at sufficiently high temperatures; however, only a portion of carbon can be captured in a solid form from oxygenated hydrocarbon fuels, with the maximum carbon capture rate being achieved at an optimum temperature. An energy analysis, which takes into account the energy penalty of CCS for the conventional power generation system, reveals that the net available energy from the proposed system is still not as high as that of the conventional system with CCS; however, the solid carbon can be of high commercial value when appropriate technology is employed to convert the carbon byproduct into a high-added-value carbon product such as carbon black or carbon nanotubes (CNTs).