Inaccuracy in arc power calculation through a product of voltage and current averages

Power is an indirect measurand, determined by processing voltage and current analogue signals through calculations. Using arc welding as a case study, the objective of this work was to bring up subsidies for power calculation. Based on the definitions of correlation and covariance in statistics, a mathematical demonstration was developed to point out the difference between the product of two averages (e.g. P = $$\overline{U} x \overline{I}$$ U ¯ x I ¯ ) and the average of the products (e.g. P = ($$\overline{UxI}$$ UxI ¯ ). Complementarily, a brief on U and I waveform distortion sources were discussed, emphasising the difference between signal standard deviations and measurement errors. It was demonstrated that the product of two averages is not the same as the average of the products, unless in specific conditions (when the variables are fully correlated). It was concluded that the statistical correlation can easily flag the interrelation, but if assisted by covariance, these statistics quantify the inaccuracy between approaches. Finally, although the statistics' determination is easy to implement, it is proposed that power should always be calculated as the average of the instantaneous U and I products. It is also proposed that measurement error sources should be observed and mitigated, since they predictably interfere in power calculation accuracy.

Effect of Cyclical Bending and Rubbing on the Characteristic Impedance of Textile Signal Lines

This article presents the results of tests on the resistance of new textile signal lines to bending and abrasion. The textile signal lines are one of the most important parts of the electronic system incorporated into modern smart garments. The main application of the lines presented in this article is the transmission of digital signals or high-frequency analogue signals. The tested lines were made of fabrics with sewn paths made of electro-conductive fabric. The construction of a measuring stand for testing the electric properties of textile transmission lines is shown. This article presents the effects of bending and abrasion on the resistance of electro-conductive strips, which are one of the elements of textile signal lines. The article also presents the effects of bending and abrasion on the characteristic impedance of constructed textile signal lines. Statistical analysis of the obtained results is also presented.

Fundamental Aspects of Audio and Music Signals

This chapter introduces and explores some basic aspects of audio and music signal processing. It first looks at analogue signals, developing in good detail the concepts of frequency, phase, and amplitude, supported by some mathematics. Simple manipulation of signals is discussed and its effects on sound waveforms are shown. The key concept of discrete signals, and the discretisation process involved in sampling is introduced. The chapter concludes with the definition of digital audio.

Experimental measurement of the cutting forces and wear of the drill in processing X17CrNi16-2 martensitic stainless steel

For the optimum setup of an industrial manufacturing process, it can be important to know the drilling forces and moments. In many cases, theoretical estimates are not accurate enough, especially when dealing with new materials, and experimental measurements are mandatory. This paper presents the design of a dynamometer comprising a one-spoked wheel elastic component to measure the drilling thrust force and the drilling moment. A finite element analysis was made, using Ansys software, to find the most favorable position for the strain gauges. One set of strain gauges was bonded to spokes to determine the torque, and a second set was bonded to the other two spokes to quantify the axial thrust force. After dynamometer manufacturing, a calibration operation is achieved, and tests are performed by measuring the drilling forces, thrust, and torque on American Iron and Steel Institute (AISI) 1020 steel. The analogue signals from the gauges were recorded using a computer with a data acquisition device. Tool wear is studied, and the results are presented in the paper. A good agreement between results from the literature and computations demonstrates the efficiency and accuracy of this measuring instrument.

Optical Axons for Electro-Optical Neural Networks

Recently, neuromorphic sensors, which convert analogue signals to spiking frequencies, have been reported for neurorobotics. In bio-inspired systems these sensors are connected to the main neural unit to perform post-processing of the sensor data. The performance of spiking neural networks has been improved using optical synapses, which offer parallel communications between the distanced neural areas but are sensitive to the intensity variations of the optical signal. For systems with several neuromorphic sensors, which are connected optically to the main unit, the use of optical synapses is not an advantage. To address this, in this paper we propose and experimentally verify optical axons with synapses activated optically using digital signals. The synaptic weights are encoded by the energy of the stimuli, which are then optically transmitted independently. We show that the optical intensity fluctuations and link’s misalignment result in delay in activation of the synapses. For the proposed optical axon, we have demonstrated line of sight transmission over a maximum link length of 190 cm with a delay of 8 μs. Furthermore, we show the axon delay as a function of the illuminance using a fitted model for which the root mean square error (RMS) similarity is 0.95.

Trigger and data acquisition systems

The quantities measured by detectors are generally analogue signals or rates which are, with few exemptions, available in electronic form and which one usually wants to further process with computers. This chapter describes the interfaces between the detector-near electronics (see chapter 17) and a computer or a computer system. In order to limit the transfer rates of the interfaces and the capacities of storage media to the necessary, the interesting events are usually selected by triggers. Data acquisition and triggering are therefore closely connected and have to be coordinated. The capabilities of data acquisition and processing have grown with high speed and will presumably further grow following the developments in computers, networks and consumer electronics. In the framework of this book only a limited inside into these developments can be given.

Signal processing via sampled-data control theory

Digital sounds and images are used everywhere today, and they are all generated originally by analogue signals. On the other hand, in digital signal processing, the storage or transmission of digital data, such as music, videos or image files, necessitates converting such analogue signals into digital signals via sampling. When these data are sampled, the values from the discrete, sampled points are kept while the information between the sampled points is lost. Various techniques have been developed over the years to recover this lost data, but the results remain incomplete. Professor Yutaka Yamamoto's research is focused on improving how we can recover or reconstruct the original analogue data.

A High-Precision Gated Integrator for Repetitive Pulsed Signals Acquisition

Gated integrating measurement method represents a widely used approach when fast, repetitive analogue signals are concerned. In this work a compact synchronized gated-integrator prototype has been realized and preliminary characterized. Front-end electronics is based on the mature high-precision switched-integrator transimpedance-amplifier IVC102 whose output is connected to a precision LT1911 inverting amplifier, whereas analogue-to-digital conversion, as well as timing control circuitry, are performed by a high-efficiency LPC845 microcontroller. Synchronizing signal detection with the external trigger generated in coincidence with a source, the proposed circuitry amplifies and integrates the signal only when the pulse is generated, displaying excellent performances in terms of linearity, sensitivity and signal-to-noise ratio. Hence, the proposed solution represents an affordable alternative to continuous-time regime measurement-techniques, usually adopted in radiation dosimetry where accuracy and sensitivity are strict requirements for treatment quality assurance.

Plug-in circuit board for the Raspberry-Pi microcomputer to reproduce multi-channel original electrocardiograms

Commercial simulators can only reproduce electrocardiograms (ECG) of the normal and diseased heart rhythm in a simplified waveform and with a low number of channels. With the presented project, the variety of digitally archived ECGs, recorded during electrophysiological examinations, should be made usable as original analogue signals for research and teaching purposes by the development of a special printed circuit board for the minicomputer “Raspberry-Pi “.