Craft

Résumé

A craft or trade is a pastime or an occupation that requires particular skills and knowledge of skilled work. In a historical sense, particularly the Middle Ages and earlier, the term is usually applied to people occupied in small scale production of goods, or their maintenance, for example by tinkers. The traditional term craftsman is nowadays often replaced by artisan and by craftsperson. Historically, the more specialized crafts with high-value products tended to concentrate in urban centers and their practitioners formed guilds. The skill required by their professions and the need to be permanently involved in the exchange of goods often demanded a higher level of education, and craftsmen were usually in a more privileged position than the peasantry in societal hierarchy. The households of craftsmen were not as self-sufficient as those of people engaged in agricultural work, and therefore had to rely on the exchange of goods. Some crafts, especially in areas such as pottery, w

Source officielle

https://en.wikipedia.org/wiki/Craft

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Two complementary measurement systems – built upon an autonomous floating craft and a tethered balloon – for lake research and monitoring are presented. The autonomous vehicle was assembled on a catamaran for stability, and is capable of handling a variety of instrumentation for in situ and near-surface measurements. The catamaran hulls, each equipped with a small electric motor, support rigid decks for arranging equipment. An electric generator provides full autonomy for about 8 h. The modular power supply and instrumentation data management systems are housed in two boxes, which enable rapid setup. Due to legal restrictions in Switzerland (where the craft is routinely used), the platform must be observed from an accompanying boat while in operation. Nevertheless, the control system permits fully autonomous operation, with motion controlled by speed settings and waypoints, as well as obstacle detection. On-board instrumentation is connected to a central hub for data storage, with real-time monitoring of measurements from the accompanying boat. Measurements from the floating platform are complemented by mesoscale imaging from an instrument package attached to a He-filled balloon. The aerial package records thermal and RGB imagery, and transmits it in real-time to a ground station. The balloon can be tethered to the autonomous catamaran or to the accompanying boat. Missions can be modified according to imagery and/or catamaran measurements. Illustrative results showing the surface thermal variations of Lake Geneva demonstrate the versatility of the combined floating platform/balloon imagery system setup for limnological investigations.

2019

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Timber folded plate Structures combine the advantages of timber as a construction material, such as its carbon-dioxide storage, low energy production and favorable weight-to-strength ratio, with the structural efficiency and elegance of folded surface structures. The construction of such surface-active structure systems with timber is a relatively new development, driven by an increasing awareness for sustainable building constructions, and enabled by new engineered wood products. However, these constructions require a large amount of edgewise joints between the thin timber plates, which are difficult to address with state-of-the-art connection techniques. Instead of using mass-produced mechanical fasteners for these connections, this thesis investigates the use of customized Integral Mechanical Attachment techniques, which use geometrical features of the parts to establish connections, rather than additional fasteners. Integral joints were common in traditional woodworking, but their manual crafting became infeasible during the industrialization. However, new computer-controlled fabrication technology, which is already available in the timber prefabrication industry, allows for an efficient, automatic production of integral joints. The advantages of such joints have already been demonstrated in framing constructions, where timber beams are used as the primary structural components. The proliferation of automatic joinery machines has repatriated customizable single-degree-of-freedom (1DOF) joints, which allow for the fast and precise assembly of prefabricated components. The objective of this thesis is to transfer these advantages to the construction of timber folded plate structures. Inspiration is taken from traditional cabinetmaking joints from Europe and Asia, as well as other industry sectors, where mass-produced integral joints are commonly used. The thesis will demonstrate several adaptations which have been made for the application of the joints on cross-laminated wood panels, for their automatic fabrication and for the customized purposes in the jointing timber folded plate structures. The geometry, fabrication and assembly of these new joints is being implemented and tested through the development of algorithmic tools. This is followed up by a verification of the proposed methods through large- and small scale physical prototypes. In its three peer-reviewed core chapters, the thesis presents investigations ranging from an initial hybrid approach, where integral joints are combined with adhesive bonding, towards a completely integral mechanical attachment solution. After a first application of the joints on a surface which is folded in one direction, the integral attachment of bidirectionally folded surfaces will be demonstrated. This is achieved through a new technique, which allows for the simultaneous jointing of multiple non-parallel edges, with single-degree-of-freedom joints. Algorithms will be presented, which allow for the automatic processing and the automatic fabrication of the joints. The automation of these processes will then be used for the construction of a doubly-curved, bidirectionally-folded surface, which obtains its structurally beneficial double-curvature through incremental changes in the geometry of the plates. [...]

EPFL2015

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EPFL2015