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IT IS customary to discuss the growth of current when a battery is connected to a coil, and the growth of voltage across a capacitor when the capacitor is charged through a resistor, at the stage when students have done some work on d.c. circuits and are about to start a.c. theory. At this elementary stage, they may, or may not, be familiar with waveforms on the oscilloscope. If they can take the oscilloscope in their stride, they might be interested in the following demonstrations. If, on the other hand, they belong to the group which regards the oscilloscope as a box that can produce any desired pattern if the knobs are twiddled long enough, the demonstration will be less convincing. The justification for the demonstration in this case would possibly be that exposing students to similar demonstrations over a long enough period may eventually convince some of them that mere rotation of the knobs is not sufficient: it may also be necessary for the theory to be correct.

The ammeter can measure the direct current and low-frequency alternating current through the wires, but it is difficult to measure complex waveforms. The oscilloscope can measure complex waveforms, but it is easy to measure the voltage waveform and difficult to measure the current waveform. Thus, how to measure complex current waveforms with oscilloscope is an important and crucial issue that needs to be solved in practical engineering applications. To solve the above problems, an active short circuit line method is proposed to measure the volt-ampere characteristic curve of chaotic circuits.

In this paper, an active short circuit line method is proposed to measure the volt-ampere characteristic curve of various chaotic circuits especially for memristive systems. A memristor-based chaotic system is introduced, and the corresponding memristor-based circuit is constructed and implemented by using electronic components.

The chaotic attractors and volt-ampere characteristic curve of the memristor-based chaotic circuit are successfully analyzed and verified by oscilloscope measurement with the proposed active short circuit line method. Accordingly, the hardware circuit experiments are carried out to validate the effectiveness and feasibility of the active short circuit line method for these chaotic circuits. A good agreement is shown between the numerical simulations and the experimental results.

The primary contributions of this paper are as follows: an active short circuit line method for measuring the volt-ampere characteristic curve of chaotic circuits is proposed for the first time. A memristor-based chaotic system is also constructed by using memristor as nonlinear term. Then, the active short circuit line method is applied to measure the volt-ampere characteristic curve of the corresponding memristor-based chaotic circuit.

IRIS is a new ultrasonic system for inspecting air‐cooled heat exchangers. It employs the conventional pulse echo technique for measuring the wall thickness, but uses a novel method for displaying the measurements. All of the measurements made during a complete scan, around the circumference of the tube, are displayed on an oscilloscope screen to produce a stationary, rectilinear picture of the circumferential cross section. Missed and false measurements are easily recognised and can be compensated for by extrapolation of the valid measurements. The novel display allows wall thicknesses to be measured, virtually down to zero in ideal circumstances.

THE Instrument Systems Division of Gould Electronics at Hainault, Essex, has developed a new digital storage oscilloscope which offers the unique combination of eight channels, independently isolated inputs and hard‐copy output facilities in a single portable unit.