28342459
Process planning optimization for the manufacture of injection moulds using a genetic algorithm
This paper reports a real application of a computer-aided process planning (CAPP) system, IMOLD_CAPP, for the manufacture of injection moulds. A combination of a template and a generative approach is used for the development of this CAPP system. The input to the system is the three-dimensional mould components developed by IMOLD. Here, the process-types and their sequences for a particular type of mould component are defined in the plan template based on company practice, while selection of machine tools, cutting tools, and cutting conditions for different processes in the plan template are optimized by a method based on genetic algorithms (GAs). The objective function of optimization is to minimize overall processing time. The performance of the optimization is compared with an algorithm based on simulated annealing (SA), and the GA-method is found to be appropriate for the optimization. This approach is expected to be applicable in most mould shops based on their available machining resources.
97577218
A study on the grinding of glass using electrolytic in-process dressing
Grinding of brittle materials such as glass is gaining importance due to the rapid developments in the areas of machining of storage devices, microlenses, and optical communication devices. Grinding of such glasses is difficult because grinding wheels wear out easily due to the hard and brittle nature of the materials being machined. Grinding wheels with fine abrasive size are required in order to achieve ductile mode grinding. Problems such as wheel loading and glazing can be encountered while grinding with fine abrasive wheels. Electrolytic in-process dressing (ELID) is an efficient method to dress the grinding wheel while performing grinding. In this paper, a fundamental study on the mechanism of the ELID grinding technique is discussed in detail. Several sets of experiments have been performed to determine the optimal grinding conditions. From the experiments, it has been established that surface roughness could be further improved if the current duty ratio to dress the grinding wheel were increased. The force patterns and the changes in the profile of the grinding wheel during machining are also presented and discussed in detail.
26262056
Molecular dynamics simulation of the effect of tool edge radius on cutting forces and cutting region in nanoscale ductile cutting of silicon
Unlike in conventional cutting processes, where the undeformed chip thickness is significant compared to the cutting tool edge radius, in nanoscale cutting processes, the undeformed chip thickness is very small, on the nanoscales. Therefore, the tool edge radius can not been ignored. It has been found that there is a brittle-ductile transition in cutting of brittle materials when the cutting tool edge radius is reduced to nanoscale and the undeformed chip thickness is smaller than the tool edge radius. In order to better understand the mechanism of the transition, a molecular dynamics (MD) method, which is different from continuous linear mechanics, is employed to model and simulate the nanoscale ductile mode cutting process of monocrystalline silicon wafer. The simulated variation of the cutting forces with the tool cutting edge radius is compared with the results of the cutting force from experimental cutting tests and they show a good agreement. In the simulated results, it can be seen that the thrust force is much larger than the cutting force in cutting. The simulated results also denote that the resultant force in the cutting process is not uniformly distributed along the cutting tool edge. In the simulation, the elastic springback of small thickness is observed on the machined workpiece surface.
15039379
From DFT to systems test-a model based cost optimisation tool
Long lasting systems like airplanes have a cost structure where the maintenance costs are larger than the purchasing costs. Testing is required, both for preventive maintenance as well as repair and a major source for cost. Previously we have analysed test and Design for Testability for digital systems, covering ASICs, boards and systems. Besides, the continuous development of technology requires cost models that can grow dynamically and, because we will never have all information, can work with incomplete data sets. In this paper we present a tool that is well suited for a wide range of applications. Previously developed cost models can be incorporated and new elements can be added to the model as needed. Due to the generic approach the tool allows modelling general systems. It is not bound to the digital domain, although it has a strong background there.
3714667
Stochastic approximations of perturbed Fredholm Volterra integro-differential equation arising in mathematical neurosciences
This paper extends the results of synaptically generated wave propagation through a network of connected excitatory neurons to a continuous model, defined by a Fredholm Volterra integro-differential equation (FVIDE), which includes memory effects of the past in the propagation. Stochastic approximation and numerical simulations are discussed.
15632777
Numerical solution of a Fredholm integro-differential equation modelling Theta-neural networks
We propose several approaches to the numerical solution of a new Fredholm integro-differential equations modelling neural networks. A solution strategy based on expansions onto standard cardinal basis functions and collocation is presented. Comparative numerical experiments illustrate specific advantages and drawbacks of the different approaches and are used to motivate alternate strategies.
61229782
A motorola MC68020-based I/O controller
45952050
Fourier-transform solution to the problem of steady-state transonic motion of a line load across the surface of an elastic half-space (the corrected Cole-Huth solution)
Abstract Considered in the present article is the problem of a line load load moving at a constant transonic speed across the surface of an elastic half-space. Solution of the problem is derived here using the method of Fourier transforms.