Loading-effects reduction using a voltmeter in series and an ammeter in parallel

This article proposes a method for reducing the loading effects when a dc voltage or current is measured in a linear circuit with a digital multimeter (DMM). In the proposed method, the voltmeter is placed in series to estimate the current, and the ammeter is placed in parallel to estimate the voltage, which is the opposite of the conventional approach. Its application is particularly of interest when the equivalent resistance between the nodes of the dc voltage (current) under measurement is high (low). In comparison with the conventional method, the relative error is up to a factor of 10 4 lower if the equivalent resistance equals the shunt (input) resistance of the DMM when a dc current (voltage) is measuredPostprint (author's final draft

The self organizing map of neighbour stars and its kinematical interpretation

The Self-Organizing Map (SOM) is a neural network algorithm that has the special property ofcreating spatially organized tepresetüatioes of various features of input signals. The resulting maps resemble realneural structures found in the cortices of developed animal brains.: Also, the SOM. has been successful in various pattern recognition tasks involving noisy signals, as for instance, speech recognition and for this reason we are studying its application to some astronomical problems. In this paper w~ present the 2-D mapping and subsequerít study of one local sample of 12000 stars using SOM. The available attributes are 14: 3-D position and velocitiesvphotometric indexes, spectral type and luminosity class. The possible location of halo, thick disk and thin disk stars is discussed. Their kinematical properties are also compared using the velocity distribution moments up to order four.Peer ReviewedPostprint (published version

Toward non-CPU activity in low-power MCU-Based measurement systems

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis article evaluates the benefits of having peripheral-triggered peripherals in a microcontroller unit (MCU) intended for low-power sensor applications. In such an architecture, the functionality is moved from the central processing unit (CPU) to the peripherals so that a peripheral is able to trigger another peripheral with non-CPU intervention. For the sensor data logging application under study, both energy consumption and measuring time are reduced by a factor of 2 with respect to the case of applying an interrupt-based approach that requires the CPU intervention.Peer ReviewedPostprint (author's final draft

A tutorial on thermal sensors in the 200th anniversary of the seebeck effect

Two noteworthy events associated to the physics of thermal sensors were demonstrated and announced in 1821, exactly two hundred years ago. The first event was the Seebeck effect, which led to the development of thermocouples. The second was the study of the thermal dependence of the resistivity of pure metals, which led to the design of resistance temperature detectors (RTD).Postprint (updated version

A microcontroller-based interface circuit for non-linear resistive sensors

This article proposes a circuit based on a microcontroller unit (MCU) for the direct measurement and linearization of non-linear resistive sensors, such as thermistors. The measurement relies on an embedded digital timer and does not require (either embedded or external) operational amplifiers or an analog-to-digital converter, thus resulting in a low-cost, low-power design solution. The circuit includes a known resistor with a twofold function: it is a reference for circuit auto-calibration purposes, and it is in parallel with the non-linear resistive sensor for linearization purposes.Postprint (updated version

Rail-to-Rail Timer-Based Demodulator for AM Sensor Signals

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper proposes a novel timer-based demodulator for low-frequency amplitude-modulated (AM) sensor signals with a rail-to-rail operating range. The demodulator extracts the amplitude of the AM signal by measuring the period of a reference signal that is altered by the AM signal itself, as already suggested in a previous paper. The rail-to-rail operation, which is the main contribution of the novel circuit, is achieved by simply but cleverly incorporating a multiplexer that enables the comparison between the two signals (reference and AM) just at the beginning and at the end of the period measurement. This new topology offers an operating range that is up to more than four times wider than that reported in the literature. The input-output characteristic in such a wider operating range is not linear, but it can be accurately modeled by a second-degree polynomial.Peer ReviewedPostprint (author's final draft

An alternative approach to generalized Pythagorean scales: generation and properties derived in the frequency domain

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Journal of mathematics and music on march 2020, available online at: http://www.tandfonline.com/10.1080/17459737.2020.1726690.Abstract scales are formalized as a cyclic group of classes of projection functions related to iterations of the scale generator. Their representatives in the frequency domain are used to built cyclic sequences of tone iterates satisfying the closure condition. The refinement of cyclic sequences with regard to the best closure provides a constructive algorithm that allows to determine cyclic scales avoiding continued fractions. New proofs of the main properties are obtained as a consequence of the generating procedure. When the scale tones are generated from the two elementary factors associated with the generic widths of the step intervals we get the partition of the octave leading to the fundamental Bézout’s identity relating several characteristic scale indices. This relationship is generalized to prove a new relationship expressing the partition that the frequency ratios associated with the two sizes composing the different step-intervals induce to a specific set of octaves.Peer ReviewedPostprint (author's final draft

Nodal and mesh analysis simplification by introducing a theorem-based preliminary step

This brief proposes a new and simplified method for the analysis of linear circuits that combines the classical mesh-current or node-voltage method with a recently-stated theorem. The beforehand application of such a theorem, which involves the insertion of an open or short circuit, in a circuit with N meshes or nodes results in a system of N- 1 linear equations for N- 1 unknowns, instead of N equations for N unknowns obtained using the conventional approach. Therefore, if the circuit is analyzed in matrix form, the resulting coefficient matrix is square of order N- 1, instead of N , thus facilitating the hand calculations. Examples of circuit analysis are provided to demonstrate the applicability and advantages of the proposed analysis method in comparison with the conventional approach.Peer ReviewedPostprint (published version

Structure of the velocity distribution of the Galactic disc: a maximum entropy statistical approach - Part I

The maximum entropy approach is proposed to describe the local structures of the veloc- ity distribution, which are collected through its sample moments. The method is used with several samples from the HIPPARCOS and Geneva-Copenhagen survey catalogues. For the large-scale distribution, the phase density function may be obtained by fitting moments up to sixth order as a product of two exponential functions, one giving a background ellipsoidal shape of the distribution and the other accounting for the skewness and for the slight shift in the ellipsoidal isocontours in terms of the rotation velocity. The small-scale distribution can be deduced from truncated distributions, such as velocity-bounded samples with |V| ≤ 51 km s−1, which contain a complex mixture of early-type and young disc stars. By fitting up to ten-order moments, the maximum entropy approach gives a realistic portrait of actual asymmetries, showing a clear bimodal pattern: (i) around the Hyades-Pleiades stream, with negative radial mean velocity and (ii) around the Sirius-UMa stream, with slightly positive radial mean velocity. The “U-anomaly” along the radial direction is estimated straightfor- wardly 30 − 35 km s−1 from the contour plots.Preprin

A microcontroller-based interface circuit for three-wire connected resistive sensors

This article proposes and experimentally characterizes a novel microcontroller-based interface circuit to read three-wire connected resistive sensors, which are quite common in industrial applications to measure, for instance, temperature. The circuit relies on measuring, via an embedded digital timer, four discharging times corresponding to four different RC circuits, which include the sensor resistance and the parasitic resistance of the wires. A prototype has been built with a commercial microcontroller measuring resistances that correspond to a Pt100 thermal sensor and with different values of wire resistance. According to the experimental results, the error, with respect to the case with null wire resistances, is lower than 25 mO for a 5-m interconnecting cable. In addition, the non-linearity error (NLE) is lower than 0.02%–0.03% full-scale span (FSS), regardless of the wire resistances and also of any potential mismatch between them.Peer ReviewedPostprint (published version