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Volume 144
Issue 2
IEE Proceedings - Science, Measurement and Technology
Volume 144, Issue 2, March 1997
Volumes & issues:
Volume 144, Issue 2
March 1997
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- Author(s): C.T.L. Phua and B.G. Dale
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 2, p. 57 –62
- DOI: 10.1049/ip-smt:19970935
- Type: Article
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The paper outlines the main findings of an examination of overmakes in a small company which manufactures complex high-technology printed circuit boards (PCBs) for the aerospace and defence industries. Overmakes relate to the practice of planning to manufacture more PCBs than required to ensure that, in the event of poor process yields, the customer receives a full batch delivery. The study has found that certain company practices such as two-panel loading, step and repeat factors and an outdated overmake planning grid have contributed to an excessive number of overmakes being manufactured and subsequently put into inventory as stock boards. A formula for planning the optimum number of overmakes has been developed and this, together with a revised overmake grid, indicates that overmakes can be reduced by almost one-third. - Author(s): A.J. Walton ; M. Fallon ; M.I. Newsam ; R.S. Ferguson ; D. Sprevak ; J.P. Elliott ; G.A. Allan
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 2, p. 63 –68
- DOI: 10.1049/ip-smt:19970860
- Type: Article
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63
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The authors present some of the simulation tools available to IC technology and circuit designers and discuss their importance in a Design For Manufacturability (DFM) strategy. It is demonstrated how these simulators, when combined with Design Of Experiment (DOE) and Response Surface Methodology (RSM), can be used to increase engineering knowledge while at the same time reducing the number of simulations required to optimise a process. The idea of contour plotting response distribution parameters to help determine robust manufacturing conditions is also introduced together with a methodology of using simulation results to rapidly produce histograms of response distributions. An environment to help automate the above approach is presented, and its use as part of a DFM strategy is illustrated through an example of a process/device optimisation. - Author(s): R.R. Leal ; P. Butler ; P. Lane ; P.A. Payne
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 2, p. 69 –72
- DOI: 10.1049/ip-smt:19970887
- Type: Article
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69
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The ability of artificial neural networks (ANNs) to learn from experience rather than from mechanistic descriptions makes them the preferred choice to model processes with intricate variable interrelations. Some of these processes can be found in the area of biotechnology. The authors aim to use ANNs and data fusion to provide better instrumentation for a fermentation process and eventually optimise its performance. Of particular interest is the robust estimation of biomass in the production of an antibiotic. Several feed-forward backpropagation neural networks (BPNs) have been chosen for the experiments using the Levenberg–Marquardt learning algorithm. Work has been carried out to test the generalisation capabilities and performance in the presence of noise and sensor failure. It has been observed that, given the appropriate training, data fusion and ANN methodology lead to estimation of these parameters with an accuracy comparable to instrumentation errors. - Author(s): N. Benjathapanun ; W.J.O. Boyle ; K.T.V. Grattan
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 2, p. 73 –80
- DOI: 10.1049/ip-smt:19970713
- Type: Article
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73
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An approach to determining the type and concentration of a range of representative contaminants, chlorine, nitrate and ammonia in waste water, based on a three-stage scheme for processing data from ultraviolet and visible (UV-Vis) spectra, is described. In simulation in the laboratory, data for the study are derived from laboratory-based measurements of such spectra from mixtures of common chemical pollutants in water at levels around their legal limits and from mathematical models based on these measurements. Through the work, it is concluded that mathematical procedures alone, i.e. self-learning, are not currently effective, while classification based on a model for absorption spectra with prior knowledge of the expected chemistry in a particular water system under study, is more likely to be successful. - Author(s): W. Krajewski
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 2, p. 81 –86
- DOI: 10.1049/ip-smt:19970858
- Type: Article
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p.
81
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The boundary element method is adapted to 2-D electric field analysis in the vicinity of HV transmission lines of alternating current. The influence of buildings placed near the line and the irregular shape of the ground are taken into account. A double-layer mathematical model of the buildings is proposed. The material parameters are expressed by the effective complex permittivity. A direct BEM formulation with the elimination of interzonal normal derivatives is employed and the appropriate boundary integral equations are derived. The computational results of the electric field distribution near the 400 kV transmission line are presented. - Author(s): X.Z. Meng and J.G.J. Sloot
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 2, p. 87 –92
- DOI: 10.1049/ip-smt:19970861
- Type: Article
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87
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When fuses are subjected to current pulses, cyclic stress is induced owing to temperature variations. Damage in the fuse elements is gradually accumulated and results in resistance increase. Consequently, current–time characteristics shift to effect early operation during the normal service period. Under such circumstances, proper protection required for other equipment will not be achieved. Reliability concerns for after sales service arise owing to these facts. The paper presents a method for predicting lifetimes of fuses for cyclic loading. The physical model is based on the description of elastic, plastic and creep deformation during a series of current pulses. In comparison with existing methods and IEC recommendations, it has the advantage of requiring a very limited number of tests. Results from the physical model can be used to evaluate practical fuse designs and provide advanced information for fuse replacements. The method has been demonstrated for commercial time-lag miniature fuses, low-voltage fuses with M-effect, low-voltage fuses for semiconductor protection, and high-voltage fuses for motor protection. - Author(s): I. Dunlop and A. McNab
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 2, p. 93 –99
- DOI: 10.1049/ip-smt:19970857
- Type: Article
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93
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To make a decision on the nature of a defect contained within a weld specimen, it is necessary to reliably detect suspect regions in the ultrasonic inspection images, derive geometrical parameters such as shape, size, position and orientation from each indication and, finally, collate these parameters intelligently by associating each indication with a possible defect type. This procedure is discussed for the case when the segmentation of indications and parameter calculation procedures are performed by the authors' NDT Workbench facility. A real-flaw example, inspected by a series of probes, is used to demonstrate the final defect categorisation decision. The indication parameters derived during this process can be used either to aid the manual interpreter or as part of a knowledge based system (KBS).
Effects of ‘overmakes’ on company performance
Total TCAD strategy for DFM in IC technology development
Data fusion and artificial neural networks for biomass estimation
Binary encoded 2nd-differential spectrometry using UV-Vis spectral data and neural networks in the estimation of species type and concentration
BEM analysis of electric field excited by overhead HV lines erected in built-up areas
Reliability concept for electric fuses
Automated parameter extraction for ultrasonic flaw analysis
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