LAYER-WISE IN-PROCESS MONITORING-AND-FEEDBACK SYSTEM BASED ON SURFACE CHARACTERISTICS EVALUATED BY MACHINE-LEARNING-GENERATED CRITERIA

In the laser powder bed fusion (PBF-LB) process, a set of parameters that are considered optimal are selected. Still, a set of parameters cannot accommodate complex model geometries, model placement in the build chamber, and unforeseen circumstances, leading to internal defects. Therefore, a new in-situ monitoring and feedback system has been developed to suppress the occurrence of lack-of-fusion (LOF) defects in the PBF-LB process. This system measures surface properties after each laser irradiation to predict whether LOF defects occur. Then, if necessary, a feedback process is performed to re-melt the same surface. Evaluation thresholds are defined by a combination of aerial surface texture parameters created in advance by machine learning of surface properties and defect occurrence. For example, a square pillar of Inconel 718 alloy built with feedback had a higher relative density than one without feedback.Mechanical Engineerin

Abstract Poisson summation formulas over homogeneous spaces of compact groups

This paper presents the abstract notion of Poisson summation formulas for homogeneous spaces of compact groups. Let G be a compact group, H be a closed subgroup of G, and μ be the normalized G-invariant measure over the left coset space G / H associated to the Weil’s formula. We prove that the abstract Fourier transform over G / H satisfies a generalized version of the Poisson summation formula

Entropic effects on the structure of Lennard-Jones clusters

We examine in detail the causes of the structural transitions that occur for those small Lennard-Jones clusters that have a non-icosahedral global minima. Based on the principles learned from these examples we develop a method to construct structural phase diagrams that show in a coarse-grained manner how the equilibrium structure of large clusters depends on both size and temperature. The method can be augmented to account for anharmonicity and quantum effects. Our results illustrate that the vibrational entropy can play a crucial role in determining the equilibrium structure of a cluster.Comment: 13 pages, 9 figure

A qualitative study on the acceptability and preference of three types of long-lasting insecticide-treated bed nets in Solomon Islands: implications for malaria elimination

Background. In March 2008, the Solomon Islands and Vanuatu governments raised the goal of their National Malaria Programmes from control to elimination. Vector control measures, such as indoor residual spraying (IRS) and long-lasting insecticidal bed nets (LLINs) are key integral components of this programme. Compliance with these interventions is dependent on their acceptability and on the socio-cultural context of the local population. These factors need to be investigated locally prior to programme implementation. Method. Twelve focus group discussions (FGDs) were carried out in Malaita and Temotu Provinces, Solomon Islands in 2008. These discussions explored user perceptions of acceptability and preference for three brands of long-lasting insecticide-treated bed nets (LLINs) and identified a number of barriers to their proper and consistent use. Results. Mosquito nuisance and perceived threat of malaria were the main determinants of bed net use. Knowledge of malaria and the means to prevent it were not sufficient to guarantee compliance with LLIN use. Factors such as climate, work and evening social activities impact on the use of bed nets, particularly in men. LLIN acceptability plays a varying role in compliance with their use in villages involved in this study. Participants in areas of reported high and year round mosquito nuisance and perceived threat of malaria reported LLIN use regardless of any reported unfavourable characteristics. Those in areas of low or seasonal mosquito nuisance were more likely to describe the unfavourable characteristics of LLINs as reasons for their intermittent or non-compliance. The main criterion for LLIN brand acceptability was effectiveness in preventing mosquito bites and malaria. Discussions highlighted considerable confusion around LLIN care and washing which may be impacting on their effectiveness and reducing their acceptability in Solomon Islands. Conclusion. Providing LLINs that are acceptable will be more important for improving compliance in areas of low or seasonal mosquito nuisance and malaria transmission. The implications of these findings on malaria elimination in Solomon Islands are discussed

Surface tensions and stress tensors of liquid and solid clusters by molecular dynamics

Surface tension and pressure (stress) tensors of Lennard-Jones clusters, in the size range $200\sim2700$ atoms/cluster, formed from evaporating liquid droplets were calculated in a Molecular Dynamics simulation. Icosahedral clusters have a much larger surface tension than decahedral, fcc, and hcp ones, meanwhile asymmetric icosahedral clusters have a lower surface tension. Fcc and hcp clusters have a very small surface tension. Decahedral clusters have a surface tension closer to that of fcc and hcp ones than to that of icosahedral ones, though both icosahedral and decahedral structures have five fold symmetry axis. Binary component clusters have a higher surface tension than single component ones