Characterisation of the cold metal transfer (CMT) process and its application for low dilution cladding

The process characteristics of the synergic cold metal transfer (CMT) process have been examined for welding aluminium alloy. Utilising a simple backlighting system and through the arc monitoring the droplet transfer modes were identified. Whilst the modified short circuit mode was evident for the lower parameter range, a two part transfer mode based upon a combination of spray and short circuit transfer was observed for the mid to upper parameter range. The technology was also explored as a cladding process for applying to ternary alloyed (Al–Cu–Mg) aluminium plate. This alloy system is known to be susceptible to solidification cracking when MIG welded using the binary Al-2319 (Al–Cu) filler wire, this being due to the wide element freezing range of the weld resulting from mixing with the base material. Utilising this filler, weld dilution ratios for both CMT and pulsed welding were identified across the examined parameter range. The CMT process exhibited greater control of dilution that enabled deposition of a quasi-binary (Al–Cu) layer exhibiting a less crack susceptible composition. Onto this layer conventional MIG welding could be applied which could potentially eradicate cracking using a binary fi

ACM/IEEE-CS information technology curriculum 2017: A status update

The IT2008 Curriculum Guidelines for Undergraduate Degree Programs in Information Technology has been showing its age, and in 2014, the ACM Education Board agreed to oversee the creation of a revision, now being referred to as IT2017. Much progress has been made, and a version 0.6 will be ready by Oct 2016. All proposed panel members are members of the IT2017 Task Group

Inherent work suit buoyancy distribution:effects on lifejacket self-righting performance

Introduction: Accidental immersion in cold water is an occupational risk. Work suits and life jackets (LJ) should work effectively in combination to keep the airway clear of the water (freeboard) and enable self-righting. We hypothesized that inherent buoyancy, in the suit or LJ, would be beneficial for enabling freeboard, but its distribution may influence LJ self-righting. Methods: Six participants consented to complete nine immersions. Suits and LJ tested were: flotation suit (FLOAT; 85 N inherent buoyancy); oilskins 1 (OS-1) and 2 (OS-2), both with no inherent buoyancy; LJs (inherent buoyancy/buoyancy after inflation/total buoyancy), LJ-1 50/150/200 N, LJ-2 0/290/290 N, LJ-3 80/190/270 N. Once dressed, the subject entered an immersion pool where uninflated freeboard, self-righting performance, and inflated freeboard were measured. Data were compared using Friedman’s test to the 0.05 alpha level. Results: All suits and LJs enabled uninflated and inflated freeboard, but differences were seen between the suits and LJs. Self-righting was achieved on 43 of 54 occasions, irrespective of suit or LJ. On all occasions that self-righting was not achieved, this occurred in an LJ that included inherent buoyancy (11/54 occasions). Of these 11 failures, 8 occurred (73% of occasions) when the FLOAT suit was being worn. Discussion: LJs that included inherent buoyancy, that are certified as effective on their own, worked less effectively from the perspective of self-righting in combination with a work suit that also included inherent buoyancy. Equipment that is approved for use in the workplace should be tested in combination to ensure adequate performance in an emergency scenario

Flexible Resolution of Authorisation Conflicts in Distributed Systems

Flexible Resolution of Authorisation Conflicts in Distributed System

The MindLab Project. Local Museums Supporting Community Wellbeing Before and After UK Lockdown

Catalyst is a science discovery centre and independent museum based in Widnes, United Kingdom. Since 2018, it has collaborated with mental health charity Mind Halton on MindLab, a science-inspired wellbeing project for local residents in an area with low access to mental health support. As twenty-first century museums are being increasingly regarded as community resources capable of producing valuable social impact, this article considers the role of museums in harnessing this potential to enhance community health and wellbeing during the COVID-19 pandemic. It reflects on the challenges encountered during this unprecedented lockdown, as well as the emerging opportunities, through the perspectives of those delivering MindLab

Eigenstrain boundary layer modelling of the yttria-partially stabilised zirconia–porcelain interface in dental prostheses

The exceptional strength and appealing aesthetics of porcelain veneered yttria partially stabilised zirconia (YPSZ) dental prostheses, has led to the widespread adoption of these materials. However, near-interface chipping of the porcelain remains the primary failure mode. Advanced experimental techniques have recently revealed significant variations in residual stress and YPSZ phase distribution at the YPSZ–porcelain interface. Therefore, in order to improve existing understanding and effectively optimise the production of these devices, an enhanced model of the YPSZ coping that includes these newly discovered phenomena is presented in this study. Macroscale stresses are shown to arise through the uneven temperatures within the coping during the sintering process and the coefficient of thermal expansion mismatch with the porcelain during veneering. In contrast, microscale stresses are driven by the YPSZ phase transformation and the associated volumetric expansion. The eigenstrain approach proposed here was found to demonstrate a good match between the phase variation determined experimentally, and the corresponding residual stress distribution showed an effective comparison with the empirical measurements. The proposed technique is a straightforward but powerful method for simulating this dominant mechanical behaviour, with significant potential to combine the resulting expressions into existing models. These enhanced simulations are the only viable approach for the precise, reliable and systematic optimisation of prosthesis production parameters that are needed to significantly reduce prosthesis failure rates.</p

Disordered monitored free fermions

Scrambling of quantum information in unitary evolution can be hindered due to measurements and localization, which pin quantum mechanical wave functions in real space, suppressing entanglement in the steady state. In monitored free-fermionic models, the steady state undergoes an entanglement transition from a logarithmically entangled critical state to area law. However, disorder can lead to Anderson localization. We investigate free fermions in a random potential with continuous monitoring, which enables us to probe the interplay between measurement-induced and localized phases. We show that the critical phase is stable up to a finite disorder, and the criticality is consistent with the Berezinskii-Kosterlitz-Thouless universality. Furthermore, monitoring destroys localization, and the area-law phase at weak dissipation exhibits power-law decay of single-particle wave functions. Our work opens an avenue to probe this phase transition in electronic systems of quantum dot arrays and nanowires and allow quantum control of entangled states