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The high demand for fast, energy-efficient, compact computational blocks in digital electronics has led the researchers to use approximate computing in applications where inaccuracy of outputs is tolerable. The purpose of this paper is to present two ultra-high-speed current-mode approximate full adders (FA) by using carbon nanotube field-effect transistors.

Instead of using threshold detectors, which are common elements in current-mode logic, diodes are used to stabilize voltage. Zener diodes and ultra-low-power diodes are used within the first and second proposed designs, respectively. This innovation eliminates threshold detectors from critical path and makes it shorter. Then, the new adders are employed in the image processing application of Laplace filter, which detects edges in an image.

Simulation results demonstrate very high-speed operation for the first and second proposed designs, which are, respectively, 44.7 per cent and 21.6 per cent faster than the next high-speed adder cell. In addition, they make a reasonable compromise between power-delay product (PDP) and other important evaluating factors in the context of approximate computing. They have very few transistors and very low total error distance. In addition, they do not propagate error to higher bit positions by generating output carry correctly. According to the investigations, up to four inexact FA can be used in the Laplace filter computations without a significant image quality loss. The employment of the first and second proposed designs results in 42.4 per cent and 32.2 per cent PDP reduction compared to when no approximate FA are used in an 8-bit ripple adder.

Two new current-mode inexact FA are presented. They use diodes as voltage regulators to design current-mode approximate full-adders with very short critical path for the first time.

The installation of automatic test equipment can result in substantial savings in fault diagnosis costs if the equipment is able to identify faults down to component level. Types and causes of faults together with techniques to identify them are discussed in the article together with financial justification for the equipment in various typical situations.

The Author's company was the first in New Zealand to install automatic insertion equipment. The paper covers the appraisal of the following systems: manual insertion; semi‐automatic insertion; and automatic component insertion. The last of these comprises various types, namely bench type, pantograph machine, computer controlled (axial lead and general) and an in‐line assembly system. The computer controlled axial lead insertion equipment including design criteria is detailed at length, with some discussion of advantages.

Jack Hollingum reports how three electronics assembly equipment suppliers are facing the challenge of changing manufacturing technology

Multicore Solders Ltd are pleased to announce that Jack Saw, Paul Salmon, Gordon Clarke and Tom Perrett have joined their commercial division. The decision of Billiton Solders, UK, to sell the assets of their profitable solder division to the Cookson group released the aforementioned personnel who will be pleased to maintain their contacts in the industry and offer the same personal service as is the Multicore tradition.

Thin films of tellurium dioxide (TeO₂) and indium oxide (In₂O₃) mixtures were investigated for γ‐radiation dosimetry purpose. Samples were fabricated using thermal vacuum evaporation technique. The electrical properties of mixed oxides thin films [(TeO₂)_1−x(In₂O₃)_x, where x=0 and 10 per cent by weight] and their changes under the influence of γ‐radiation were investigated. Samples with contacts having a planar structure showed increase in the values of current with the increase in radiation dose up to a certain dose level. Thin films in the form of pn‐junctions were fabricated with (TeO₂)_1−x(In₂O₃)_x as p‐type material and sulphur as n‐type material. These pn‐junctions exhibited Zener diode behaviour. The current‐voltage characteristics for as‐deposited and γ‐irradiated samples were recorded. The level of response for all the fabricated devices was found to be highly dependent on the composition of the exposed material.

Let \cal N be a consistent connected network including independent voltage and current sources, positive linear resistors, multiterminal weakly no‐gain non‐linear resistors and equal numbers of nullators and norators, U(\cal N) a voltage appearing between a distinguished pair of nodes and I(\cal N) a current flowing in a distinguished branch in an equilibrium state of \cal N. It is proved that, under conditions detailed in the paper, U(\˜cal N¹)≤ U(\cal N) ≤ U(\˜cal N²) and I(\overline \cal N^\raise1pt1) ≤ I(\cal N) ≤ I(\overline \cal N^\raise1pt2) where \˜cal N¹,\˜cal N²,\overline \cal N^\raise1pt1, and \overline \cal N^\raise1pt2, are networks derived from \cal N by replacing non‐linear resistors by open‐ and/or short‐circuit structures. An earlier combinatorial method of estimating solutions of non‐linear resistive networks is extended to cover networks including active elements. The method is tested on simple examples of active diode‐transistor circuits.

To provide a numerical technique for the quick and simple determination of the switching time instants for field‐circuit coupled problems with switching elements.

3D magnetic vector potential formulation coupled to an electrical circuit with switching elements, for example, diodes, is presented. The change of the state of the switching elements is implemented as a modification of the model topology.

Since every step of the singly diagonally implicit Runge‐Kutta methods delivers not only the solution of this time step but also its stage derivatives, they can be efficiently employed to construct a dense‐output‐based interpolation polynomial, with their roots approximating the switching time instants.

This paper presents a computationally cheap interpolation approach for quick and accurate determination of switching time instances for field‐circuit coupled problems with switching elements. The proposed technique can be successfully incorporated into software packages designed to model coupled problems of different nature, where sudden changes of quality may take place.

Computers need clean, reliable, electrical power. The various faults of electrical power, such as spikes, sags, outages, noise, frequency variations, and static electricity, are defined and described. Preventive measures that computer users can employ to reduce the potential of electrical problems are discussed, as are the processes for detecting, diagnosing, and curing electrical problems when they do occur. Sidebars consider: transformers; power distribution units (PDUs); surge currents/ linear and non‐linear loads; and sizing the power conditioning system. The next issue will conclude this series with an article on uninterruptible power supplies and a bibliography.