0000000000008954
AUTHOR
S. Casans
Design of a virtual instrument for water quality monitoring across the Internet
Abstract This article presents the design of a new distributed and multi-platform system for water quality monitoring, enhanced with powerful Internet capabilities. The measured variables are temperature, turbidity, pH, dissolved oxygen, and electrical conductivity. The signal-conditioning block has been simplified through the use of software routines for thermal compensation, hence, reducing the cost and dimensions. The system offers a wide variety of Internet capabilities, like e-mail alarm notifications, automatic storage of measured data in a remote machine via the FTP protocol, dynamic generation of HTML reports, real time graphs, and indicators visible from a remote web browser, etc. …
Novel Resistance Measurement Method: Analysis of Accuracy and Thermal Dependence with Applications in Fiber Materials
Material resistance is important since different physicochemical properties can be extracted from it. This work describes a novel resistance measurement method valid for a wide range of resistance values up to 100 GΩ at a low powered, small sized, digitally controlled and wireless communicated device. The analog and digital circuits of the design are described, analysing the main error sources affecting the accuracy. Accuracy and extended uncertainty are obtained for a pattern decade box, showing a maximum of 1 % accuracy for temperatures below 30 ∘ C in the range from 1 MΩ to 100 GΩ. Thermal analysis showed stability up to 50 ∘ C for values below 10 GΩ and systematic deviations for higher …
Sensor Node Network for Remote Moisture Measurement in Timber Based on Bluetooth Low Energy and Web-Based Monitoring System
This paper proposes an IoT system based on wireless BLE connectivity to monitor the moisture content of wood, using a compact and low-cost moisture device that relies on a resistance measurement method valid for an ultra-wide range of resistance values. This device is digitally controlled with a BLE-incorporated micro-controller characterized by its small size and low power consumption, providing long-life battery. The proposed system consists of two main parts: first, the BLE moisture device including the moisture content measurement and wireless capability (BLE)
Control circuit design of the L-LC resonant inverter for induction heating
In this article, the frequency variation control strategy for an induction heating L-LC resonant inverter is analyzed. The control consists of three loops, which are analyzed and reduced to their corresponding small-signal block diagrams. From these diagrams, the optimal structure of the compensation network and the design boundaries for first order closed-loop response are derived. The special case of phase limitation is analyzed because it is unstable in open-loop operation. Finally the implementation of the control circuit is described and experimental results are shown.
Parameterizing non-linear magnetic cores for PSpice Simulation
Abstract. In this paper the main Jiles & Atherton parameters of a magnetic material, according to their particular working condition (mainly frequency, temperature and waveform) are calculated by means of a systematic procedure that use PSpice and MathCad. The modelled magnetic material is used for power electronics circuit simulation, which uses magnetic materials, working at frequencies in the region of kH, to construct transformers and inductors. Magnetic materials are the most critical components in electronics simulators due to their nonlinear behaviour and the accuracy in the simulation can only be obtained through a proper magnetic material modelling. This paper examines the modellin…
Improving bleeding detector features for electron intraoperative radiotherapy
Abstract Purpose The aim of this work is to improve the potential bleeding detection during intraoperative radiotherapy with linac polymethyl methacrylate applicators (PMMA), based on one previously developed. The improvements carried out have been focused on: i) minimizing the impact of the detector on the visual through the plastic applicators and ii) avoiding the asymmetry in the detection capability when the applicator is tilted. Methods Simulations have been made to select the geometry that provides a reduced visual impact on the applicator as well as allowing an independent response with the tilting angle of the applicator. A low-noise circuit for signal conditioning has been develope…
An electrical current smart transducer based on PSoC platform and integrated spin-valve sensor with embedded thin film Ruthenium temperature sensor
This work presents an intelligent electrical current sensor that combines a programmable system on chip (PSoC) with a microfabrication of a giant magnetoresistance sensor (GMR) and resistive temperature detector (RTD). Four spin-valve GMR elements configured in a Wheatstone bridge sense the electrical current, while a thin film RTD based on Ruthenium measures the temperature for spin-valve bridge sensitivity thermal compensation. The mixed signal PSoC allows implement in a single chip all electronic circuits needed to design a smart transducer: the spin-valve biasing, conditioning signal, analog to digital converter, digital signal processing and ports for communications. In the experimenta…
Detector for monitoring potential bleeding during electron intraoperative radiotherapy
Purpose: The aim of this work is to develop a bleeding detector integrated into the acrylic circular applicators for specific mobile linacs. Thus, a bleeding detector has been developed based on a capacitive sensor to be used with plastic applicators, as in the case of LIAC HWL from Sordina IORT Technologies SpA. According to the clinical impact, we have selected 0.5 cm as the minimum depth of fluid that should be detected. Methods: An experiment was developed using water-simulating blood. Two setups were considered: non-beveled applicators with 7 cm and 10 cm diameter. Measurements were done for applicators 0 degrees and 45 degrees tilted, both with respect to the horizontal surface, in or…
Novel constant current driver for ISFET/MEMFETs characterization
Abstract In the present work a new constant current driver for ISFETs and MEMFETs sensors has been developed. The proposed circuit maintains the ISFET/MEMFET operation point at constant drain–source current and voltage. The combination of some programmable current sources and an appropriate selection of a simple precision resistor allow a good ISFET/MEMFET polarization. The use of operational amplifiers with low offset and drift are required to provide the buffering function needed by the sensor.
ISFET drawbacks minimization using a novel electronic compensation
Ion sensitive field effect transistor (ISFET) and membrane field effect transistor (MEMFET) have some drawbacks related to: long-term drift, hysteresis and thermal drift. These factors limit the accuracy of ISFET/MEMFET based measurements systems, specially for continuous or long period measurements. Due to its accuracy, repeatability and easy-to-use features, electronic instrumentation systems are the best tools to design ISFET/MEMFET based measurement systems. A well-designed hardware and a qualified virtual instrumentation software are the key factors to overcome and compensate hysteresis, thermal and long-term drifts ISFET/MEMFET limitations. The paper is dedicated to show an instrument…
Novel voltage-controlled conditioning circuit applied to the ISFETs temporary drift and thermal dependency
This paper describes a novel conditioning circuit applied to ion-sensitive field-effect transistors/membrane-ion-sensitive field-effect transistors (ISFETs/MEMFETs) sensors. The novel conditioning circuit allows the sensor polarization with the needed either voltage or current required in each application, thanks to two completely independent voltage-controlled blocks (current and voltage blocks). The control of the voltage block is the most critical point in our design because the voltage block maintains the sensor feedback stable, avoiding the thermal and temporary drifts of the sensor feedback.
High resistance measurement circuit for fiber materials: Application to moisture content estimation
Abstract Measuring very high resistance values is a difficult task since low voltage or currents are present and thus, noise and amplification must be carefully done, especially when low resistance values are required to be measured using the same circuit, too. This work proposes a novel and accurate measurement instrument for a wide range of resistance values oriented to portable applications, i.e. low power and low supply voltage (5 V) for battery operated equipment, with a small circuit design including analog sensing, digital interface (data reading and control) using a microcontroller and external communication. The proposed circuit includes an inverter attenuator with layout and confi…
Obtaining the electrical model of a power transformer by means of finite element software
Abstract. The behaviour of transformers and inductors working at high-frequencies and high power density can dramatically differ from the ideal or low-frequency operation. Their performance is very dependent on the magnetic material, operating frequency and physical construction. In this paper, finite element analysis (FEA) is used to obtain an accurate characterization of the electromagnetic behaviour of these magnetic components.
Sensor Network to Measure Electric Parameters
Present paper covers the design of a sensor network to measure electric parameters taking into consideration that all needed components are available in the market as commercial products. The work is oriented to the integration of these existing devices and to give extra functionalities. The final functionality and the connection among the used components are provided by the software. The present paper gives special consideration to the software structure. The described system becomes a tool to be used for energy efficiency applications