Three models of different stent designs implanted in a cerebral aneurysm, originating from the Virtual Intracranial Stenting Challenge 2007 (visc'07), are meshed and the flow characteristics simulated using commercial Computational Fluid Dynamics (cfd) software in order to investigate the effects of non-Newtonian viscosity and pulsatile flow. Conventional mass inflow and Wall Shear Stress (wss) output are used as a means of comparing the cfd simulations. In addition, a wss distribution is presented, which clearly discriminates in favour of the stent design identified by other groups. We conclude that non-Newtonian and pulsatile effects are important to include in order to avoid underestimating wss, understand dynamic flow effects and to discriminate more effectively between stent designs.
In some mechanical engineering devices the novelty or inventive step of a patented design relies heavily upon how geometric features contribute to device functions. Communicating the functional interactions between geometric features in existing patented designs may increase a designer's awareness of the prior art and thereby avoid conflict with their emerging design. This paper shows how functional representations of geometry interactions can be developed from patent claims to produce novel semantic graphical and text annotations of patent drawings. The approach provides a quick and accurate means for the designer to understand the patent that is well suited to the designer's natural way of understanding the device. Through several example application cases we show the application of a detailed representation of functional geometry interactions that captures the working principle of familiar mechanical engineering devices described in patents. A computer tool that is being developed to assist the designer to understand prior art is also described.
Classical dimensional analysis in its original form starts by expressing the units for derived quantities, such as force, in terms of power products of basic units etc. This suggests the use of toric ideal theory from algebraic geometry. Within this the Graver basis provides a unique primitive basis in a well-defined sense, which typically has more terms than the standard Buckingham approach. Some textbook examples are revisited and the full set of primitive invariants found. First, a worked example based on convection is introduced to recall the Buckingham method, but using computer algebra to obtain an integer matrix from the initial integer matrix holding the exponents for the derived quantities. The matrix defines the dimensionless variables. But, rather than this integer linear algebra approach it is shown how, by staying with the power product representation, the full set of invariants (dimensionless groups) is obtained directly from the toric ideal defined by . One candidate for the set of invariants is a simple basis of the toric ideal. This, although larger than the rank of , is typically not unique. However, the alternative Graver basis is unique and defines a maximal set of invariants, which are primitive in a simple sense. In addition to the running example four examples are taken from: a windmill, convection, electrodynamics and the hydrogen atom. The method reveals some named invariants. A selection of computer algebra packages is used to show the considerable ease with which both a simple basis and a Graver basis can be found.
The increasing complexity of patented mechanical designs means that their novelty and inventive steps increasingly rely on interacting geometric features and how they contribute to device functions. These features and interactions are normally incorporated in patents through clear patent claims. However, patents can be difficult to interpret and understand for designers due to their legal terminologies. This suggests there is a need for greater awareness of relevant prior art amongst designers in terms of avoiding potential conflict. This paper presents a framework that helps designers obtain insight on relevant prior art and enables emerging design-prior art comparison. The framework mainly contains development of a patent graphical functional representation, a domain-specific ontology and a semantic database. The graphical representation presenting the functional reasoning of patents in terms of interacting geometric features. A domain-specific ontology enables knowledge sharing and conceptualisation, providing a standardised vocabulary for describing patented designs. By formulating patent data into a semantic database, commonality of working principles between an emerging design and prior art can be identified. This enables early identification of potential conflict and thereby could help designers steer their emerging designs away from protected solutions. A computer tool being developed based on this approach is also described.
This paper presents a novel method of patent mapping for visualising conflicts between patent claims that incorporates the Theory of Inventive Problem Solving (TRIZ). The method uses TRIZ engineering parameters as the criteria for evaluating dissimilarities between patent claims, producing a visualisation based on Multi-Dimensional Scaling (MDS) that can be compared with legal judgments.The advantages of the method are that it (a) reduces evaluation complexity by transforming claim-toclaim comparisons into claim-to-criteria comparisons, and (b) provides a means of comparing judgement standards between different legal authorities in mechanical engineering terms. Reliability and validity of the method are tested through focus groups using a case study on aircraft seats. The scope of the method is limited to the field of mechanical inventions.
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