Influence of Macro-Roughnesses on Vertical Slot Fishways

To restore the ecological continuity of European rivers and streams and more specifically the free circulation of aquatic species, vertical slot fishways (VSF) are built to offer the possibility for fish to cross dams or weirs. Initially, such devices were constructed to allow the migration of fish species with an important swimming capacity like salmonids. Currently, more and more VSFs are equipped with macro-roughnesses fixed on their bed to help small or benthic species to cross obstructions. Macro-roughnesses are most often stones or concrete cylinders and have been introduced to decrease the velocity and the turbulent kinetic energy of the flow inside pools. In this paper, unsteady 3D flow simulations are carried out to study the effects of such macro-roughnesses on the flows. LES simulations, validated in a previous paper with experimental results, provide valuable information of the flow characteristics

Functional architecture and specifications for Tolerancing Data and Knowledge Management

Part 1: Knowledge ManagementInternational audienceThe paper deals with the Computer-Aided Tolerancing and Product Data Management. It is especially focus on data and knowledge management system to support and improve the tolerancing tasks in product development process. The first part of the paper introduces an overview about the recent developments related to tolerancing supports and data management systems. Based on a literature survey and industrial issues, the second part proposes a functional architecture and specifications of the data and knowledge manage-ment system addressing the numerous needs clarified by tolerancing experts

Les fouilles de Timgad

Ballu Albert. Les fouilles de Timgad. In: Bulletin Monumental, tome 65, année 1901. pp. 415-433

Toward an Automatic Generation of Part Models with Form Error

AbstractMore and more research works on assembly tolerance simulation is considering not only orientation and position deviations, but also form errors. In this paper, we describe a process to generate skin model shapes, i.e. 3D models with form error, from the CAD model of a part. We study several different methods used for generating discrete models with defects, and these methods are applied to an identical CAD model to point out their differences. The work will be of benefit for choosing and applying of these different generation approaches, and for automating the generation of skin model shapes

Geometrical reliability of overconstrained mechanisms with gaps

Reliability design relates generally to simulation of fatigue strength, thermal effects, etc. not to simulation of geometrical variations, i.e. tolerancing. The variables for geometrical reliability are manufacturing, gap and functional deviations. In case of isoconstrained mechanisms, the linear expression of dependencies between these variables allows to calculate failure probability. For overconstrained mechanisms, these linear expressions are not applicable for the whole behaviour of the mechanism; nevertheless, they are applicable for each particular configuration of contacts. The different configurations represent events taken into account in a numerical evaluation assumed by the Form–Sorm method. A case study, with numerical results, illustrates and validates the chosen process