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.
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.
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.
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.
61229782
A motorola MC68020-based I/O controller
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.
62747469
An efficient numerical technique to calculate buffer statistics
Abstract A numerical solution is presented for obtaining the buffer statistics of a G / G /1 queue. The moment generating function G M ( z ) of the number of blocks buffered at the completion of a service is assumed to be known via the Pollaczek Khinchine formula. Only finite number of arrivals during a service time are allowed. To compute the buffer statistics, poles of the denominator polynomial of G M ( z ) and the residue at each pole are evaluated. The procedure is very efficient and stable; the computational complexity grows slowly as the order of the polynomial increases.