Effect of Powder Recycling on Defect Formation in Electron Beam Melted Alloy 718

The extent to which powder recycling can be permitted before risking a loss in performance of critical components is a major aspect for the viability of electron beam melting (EBM). In this study, the influence of powder oxidation during multi-cycle EBM processing on the formation of oxide-related defects in Alloy 718 is investigated. The amount of defects and their distribution in samples produced from virgin and re-used powder is studied by means of image analysis and oxygen measurements. Morphological analysis using scanning electron microscopy is performed to understand their origin and formation mechanism. The results indicate a clear correlation between the powder oxygen content and the amount of oxide inclusions present in the investigated samples. The inclusions consist of both molten and unmolten Al-rich oxide which originates from the surface of the recycled powder. Upon interaction with the electron beam, the oxide tends to cluster in the liquid metal and form critical sized defects. Hot isostatic pressing can be successfully used to densify samples produced from virgin powder. However, in the material fabricated from recycled powder, a considerable amount of damage relevant oxide inclusion defects remain after HIP treatment, especially in the contour region. It is suggested that the quality of EBM-processed Alloy 718 is at present dependent on the oxygen level in the powder in general, and on the surface chemistry of the power in particular, which needs to be controlled to maintain a low amount of inclusions

Quality Management in Project Management Consulting. A Case Study in an International Consulting Company

The present paper addresses quality management from the specific perspective of project management consulting service providers, in the framework of large infrastructure projects. Because of their supposed superiority in knowledge and experience, project management consultants have an ultimate responsibility for the proper implementing of the project. Therefore, quality management in consulting organizations should focus on critical success factors. As there is no consensus yet regarding the most important aspects of the consulting activity on which depend the achievement of the project aims, there is scope for further investigating this subject. Here, the case of a project management consulting organization involved in large infrastructure projects in Romania, Bulgaria, Moldova, Ukraine and Serbia is analyzed. Data collected through a questionnaire-based survey among international consultants and support personnel suggest that factors related to leadership style and communication skills are more closely tied to the success of the project than more technical aspects. The results constitute an empirical evidence of main success factors for specialized consulting services in project management and can be useful in improving business and project performance and achieving business excellence

COMPETITIVENESS ASESSMENT: AN OVERVIEW

Measuring competitiveness of companies, industries or nations and their ranking according to the level and dynamics became, for several decades already, a significant concern for scholars. Competitiveness should be approached in a multi-layered and comprehensive manner, considering that it has a specific content and is perceived differently depending on the system involved. In our view, a comprehensive approach has to adress five levels, facilitating a rigorous and consistent approach to variables that determine competitiveness. These levels are

On the Impact of Indirect WAN Routing on Geo-Replicated Storage

International audience—Micro-clouds infrastructures allow supporting applications on local and energy-efficient resources. Communication between micro-clouds takes place on shared and non-dedicated Internet links. Network control and optimization can only happen at the edge. For availability and persistence, the storage of application data must be geo-replicated. Maintaining strong data consistency under concurrent accesses requires delay-sensitive coherence protocols, linking the performance of the storage to that of the network linking micro-clouds. We evaluate if the use of network control at the edge of a European-wide multi-site testbed, together with appropriate network monitoring , can allow improving the performance of ZooKeeper, a strongly-consistent replicated store. Our approach leverages the indirect routing of coherence protocol traffic in the presence of network triangle equality violations. We analyze the impact on storage of variations in WAN performance, and show how the use of traffic redirection can help reducing it

OpenStack-based clouds as holons: A functional perspective

The generalization of distributed systems-of-systems lead to increasing management and operation complexity. A sound approach to deal with this complexity is to leverage overlay networks and the higher level of abstraction they allow for distributed operations. In particular, the virtualization of underlying network resources allows providing a range of reusable network services and compose them with existing systems. Recently, the notion of holons as compositional systems entities was proposed as a general framework for the programming and deployment of complex systems of systems. We investigate if this abstract model can be applied to the complex process of real-time composition of OpenStack-based IaaS clouds. In this context, we also address issues related to the energy-performance tradeoff using techniques similar to those involving dynamic service consolidations. Our solution aims at simplifying the life of infrastructure and service providers, allowing them to face the dynamicity of new demands in Future Internet

On the impact of indirect WAN routing on geo-replicated storage

Micro-clouds infrastructures allow supporting applications on local and energy-efficient resources. Communication between micro-clouds takes place on shared and non-dedicated Internet links. Network control and optimization can only happen at the edge. For availability and persistence, the storage of application data must be geo-replicated. Maintaining strong data consistency under concurrent accesses requires delay-sensitive coherence protocols, linking the performance of the storage to that of the network between micro-clouds. We evaluate if the use of network control at the edge of a European-wide multi-site testbed, together with appropriate network monitoring, can allow improving the performance of ZooKeeper, a strongly-consistent replicated store. Our approach leverages the indirect routing of coherence protocol traffic in the presence of network triangle equality violations. We analyze the impact on storage of variations in WAN performance, and show how the use of traffic redirection can help reducing it