11875786
A cost-efficient high-performance bit-serial architecture for robot inverse dynamics computation
A novel cost-efficient parallel and pipelined bit-serial array architecture is proposed for the computation of robot inverse dynamics. It achieves a certain bit-serial execution-time lower bound. The core of the system consists of two arrays of multifunctional bit-serial cells. One of the arrays computes the forward iterations, and the other one evaluates the backward recursions, of the Newton-Euler dynamics algorithm. At the current state of technology, the resulting high-performance system may be realized in only two custom VLSI chips and a minimum number of first-in-first-out register files. The organization, operation, and performance of the proposed array structure is discussed. The architecture and functionality of an individual multifunctional bit-serial cell used as the building block of the array structure is described.
61229782
A motorola MC68020-based I/O controller
135911643
Method of dry-etching evaluation using quantum dots
Abstract New dry-etch processes, such as low-power reactive-ion etching (RIE) and electron cyclotron resonance, offer very low levels of residual lattice damage. These levels are below the resolution limits of traditional characterisation methods like Raman, photoluminescence, Schottky diode, etc. We show that the single-electron charging of a quantum dot fabricated using dry etching offers a very sensitive method of damage detection. For SiCl 4 SiF 4 RIE of GaAs we find a defect density of around 1015 cm−3, which is at the level of the background impurity concentration in the as-grown material.
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.
137236624
Quantum electron beam probe of sidewall dry-etch damage
Damage as a result of ion bombardment may occur both at top surfaces and at sidewalls. We propose a method of probing sidewall damage using coherent electron focusing. A collimated electron beam is reflected off an internal boundary formed by dry etching. Spectra measured in an applied magnetic field are influenced strongly by increased levels of etch damage. Monte Carlo simulations combined with experiments on multiple beams reveal the separate contributions of boundary roughness and inelastic electron scattering. Electrostatic calculations reveal a damage shadow beneath the sidewall.
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.
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.