Retrofit versus new-build house using life-cycle assessment

This paper reports the findings of research on the environmental performance of two case-study houses, a retrofit and new build. The retrofit was completed to a Passivhaus standard while the new build was completed to current Irish building regulations. Environmental performance of the retrofit and new build was measured using life-cycle assessments, examining the assembly, operational and end-of-life stage over life spans of 50 and 80 years. Using primary information, life-cycle assessment software and life-cycle assessment databases the environmental impacts of each stage were modelled. The operational stage of both case studies was found to be the source of the most significant environmental damage, followed by the assembly and the end-of-life stage respectively. The relative importance of the assembly and end-of-life stage decreased as the life span increased. It was found that the retrofit house studied outperformed the new build in the assembly and operational stage, whereas the new build performed better in the end-of-life stage; however, this is highly sensitive, depending on the standards to which both are completed. Operational energy savings pre- and post-retrofit were significant, indicating the future potential for adoption of high-quality retrofitting practices.

Multiple Luminaire Identification in Airborne Images of Airport’s Approach Lighting Using Mathematical Morphology With Variable Length Structuring Element

The increasing demand for fast air transportation around the clock
has increased the number of night flights in civil aviation over
the past few decades. In night aviation, to land an aircraft, a
pilot needs to be able to identify an airport. The approach
lighting system (ALS) at an airport is used to provide
identification and guidance to pilots from a distance. ALS
consists of more than $100$ luminaires which are installed in a
defined pattern following strict guidelines by the International
Civil Aviation Organization (ICAO). ICAO also has strict
regulations for maintaining the performance level of the
luminaires. However, once installed, to date there is no automated
technique by which to monitor the performance of the lighting. We
suggest using images of the lighting pattern captured using a camera
placed inside an aircraft. Based on the information contained
within these images, the performance of the luminaires has to be
evaluated which requires identification of over $100$ luminaires
within the pattern of ALS image. This research proposes analysis
of the pattern using morphology filters which use a variable
length structuring element (VLSE). The dimension of the VLSE changes
continuously within an image and varies for different images.
A novel
technique for automatic determination of the VLSE is proposed and
it allows successful identification of the luminaires from the
image data as verified through the use of simulated and real data.

Functional analysis of the large periplasmic loop of the Escherichia coli K-12 WaaL O-antigen ligase

WaaL is a membrane enzyme implicated in ligating undecaprenyl-diphosphate (Und-PP)-linked O antigen to lipid A-core oligosaccharide. We determined the periplasmic location of a large (EL5) and small (EL4) adjacent loops in the Escherichia coli K-12 WaaL. Structural models of the EL5 from the K-12, R1 and R4 E. coli ligases were generated by molecular dynamics. Despite the poor amino acid sequence conservation among these proteins, the models afforded similar folds consisting of two pairs of almost perpendicular alpha-helices. One alpha-helix in each pair contributes a histidine and an arginine facing each other, which are highly conserved in WaaL homologues. Mutations in either residue rendered WaaL non-functional, since mutant proteins were unable to restore O antigen surface expression. Replacements of residues located away from the putative catalytic centre and non-conserved residues within the centre itself did not affect ligation. Furthermore, replacing a highly conserved arginine in EL4 with various amino acids inactivates WaaL function, but functionality reappears when the positive charge is restored by a replacement with lysine. These results lead us to propose that the conserved amino acids in the two adjacent periplasmic loops could interact with Und-PP, which is the common component in all WaaL substrates.