230,529 research outputs found
Review of research in feature-based design
Research in feature-based design is reviewed. Feature-based design is regarded as a key factor towards CAD/CAPP integration from a process planning point of view. From a design point of view, feature-based design offers possibilities for supporting the design process better than current CAD systems do. The evolution of feature definitions is briefly discussed. Features and their role in the design process and as representatives of design-objects and design-object knowledge are discussed. The main research issues related to feature-based design are outlined. These are: feature representation, features and tolerances, feature validation, multiple viewpoints towards features, features and standardization, and features and languages. An overview of some academic feature-based design systems is provided. Future research issues in feature-based design are outlined. The conclusion is that feature-based design is still in its infancy, and that more research is needed for a better support of the design process and better integration with manufacturing, although major advances have already been made
Physicality in Australian patent law
It is generally understood that the patent system exists to encourage the conception and disclosure of new and useful inventions embodied in machines and other physical devices, along with new methods that physically transform matter from one state to another. What is not well understood is whether, and to what extent, the patent system is to encourage and protect the conception and disclosure of inventions that are non-physical methods – namely those that do not result in a physical transformation of matter. This issue was considered in Grant v Commissioner of Patents. In that case the Full Court of the Federal Court of Australia held that an invention must involve a physical effect or transformation to be patentable subject matter. In doing so, it introduced a physicality requirement into Australian law. What this article seeks to establish is whether the court’s decision is consistent with the case law on point. It does so by examining the key common law cases that followed the High Court’s watershed decision in National Research Development Corporation v Commissioner of Patents, the undisputed authoritative statement of principle in regard to the patentable subject matter standard in Australia. This is done with a view to determining whether there is anything in those cases that supports the view that the Australian patentable subject matter test contains a physicality requirement
Revisiting the thermodynamics of hardening plasticity for unsaturated soils
A thermodynamically consistent extension of the constitutive equations of
saturated soils to unsaturated conditions is often worked out through the use a
unique 'effective' interstitial pressure, accounting equivalently for the
pressures of the saturating fluids acting separately on the internal solid
walls of the pore network. The natural candidate for this effective
interstitial pressure is the space averaged interstitial pressure. In contrast
experimental observations have revealed that, at least, a pair of stress state
variables was needed for a suitable framework to describe
stress-strain-strength behaviour of unsaturated soils. The thermodynamics
analysis presented here shows that the most general approach to the behaviour
of unsaturated soils actually requires three stress state variables: the
suction, which is required to describe the invasion of the soil by the liquid
water phase through the retention curve; two effective stresses, which are
required to describe the soil deformation at water saturation held constant.
However a simple assumption related to the plastic flow rule leads to the final
need of only a Bishop-like effective stress to formulate the stress-strain
constitutive equation describing the soil deformation, while the retention
properties still involve the suction and possibly the deformation. Commonly
accepted models for unsaturated soils, that is the Barcelona Basic Model and
any approach based on the use of an effective averaged interstitial pressure,
appear as special extreme cases of the thermodynamic formulation proposed here
- …