1,721,057 research outputs found
Automatic compensation system for impedance measurement
Full text linkThis paper deals with the realization of the four-pair terminal definition of impedance standards. A simple, though reliable, system is described that allows an automatic compensation of the voltage at the low potential port of impedance standards to be obtained. Such a system employs a commercial data acquisition board and a signal generator with adjustable-phase capability, which acts as the phase reference for the generator that feeds the impedance standard. A standard PC controls the whole system and implements the demodulation and the control algorithms. Preliminary tests have been performed in the frequency range of 50 Hz to 20 kHz with different kinds of impedance standards (resistive, inductive and capacitive), obtaining a residual voltage at the low potential port of less than 5 μV
Niobium Pentaoxide Thin-Film Gas Sensor for Portable Acetone Sensing
Full text linkAcetone gas sensing finds application in several fields such as biomedical applications, food industry, chemical manufacturing and environmental monitoring. Often, such applications require good sensing performance and portability of the sensing devices. This paper proposes a conductometric gas sensor based on a thin-film of Nb2O5 able to detect acetone at the sub-ppm level with good selectivity and repeatability. The quite small dimensions and the low power consumption make the proposed sensor suitable for portable applications
Garden building diagnostic systems for sustainable preservation
Full text linkA garden building located in Torino, 25 VERDE, designed by the architect Luciano Pia is object of a monitoring diagnostic campaign, started in 2016 and still in progress, for ensuring a long-lasting sustainable preservation. The residential complex of sixty-three apartments conceived as a habitable forest in which almost 200 trees cut down the fine dust caused by cars, is characterized by irregularly shaped terraces, supported by weathering steel tree-like structures. The weathering steels or high-strength low alloy steels have a unique interesting characteristic: they corrode under proper environmental conditions, forming a compact and tightly adherent oxide barrier that seals out the atmosphere and retards further corrosion. Dry and wet cycles create a protecting patina layer, meanwhile the constant presence of humidity and of aggressive gaseous pollutants (SO2, NOx, etc) in the atmosphere degrades the properties of the layer. The diagnostic intervention is centered in the monitoring of the weathering steel structures by means of in situ electrochemical techniques, as Electrochemical Impedance Spectroscopy (EIS). The experimental data confirm that the high sensitivity and low invasiveness of EIS makes it a powerful technique for corrosion assessment of metallic structures exposed outdoor
How to successfully classify EEG in motor imagery BCI: a metrological analysis of the state of the art
No full textA client-server architecture for distributed measurement systems
Full text linkThis paper describes a client-server architecture for the remote control of instrumentation over the Internet network. The proposed solution allows multiuser, multi-instrument sessions by means of a queueing and instrument locking capability. Client applications can be easily developed by using conventional high-level programming languages or well-assessed virtual instrumentation frameworks. Performance tests are reported; they show the low overhead due to network operation with respect to the direct control of instrumentatio
Smart thermocouples for in-line lyophilization monitoring
Full text linkThe paper describes design, development and characterization of a measuring system for in-line temperature monitoring during freeze-drying of harmaceutical chemicals. T-type thermocouples with sub-micrometric thickness deposited via plasma-coated with SiOx film and embedded into the vial walls have been realised as prototypes and successfully tested. The measuring system does not alter the vial shape and its thermal conductivity and does not react with the lyophilized product thus avoiding any interference with the lyophilization process
Un modello three-layer per telerilevamento distribuito
No full textIl rilievo di parametri ambientali sta acquisendo un'importanza crescente in molteplici campi di interesse tra i quali, ad esempio, la salute pubblica, il monitoraggio di agenti a rischio di incolumità in insediamenti industriali, o del livello di inquinanti dovuti al traffico in aree urbane, la salvaguardia di aree idrogeologiche. La diffusione delle problematiche legate all'ambiente ha introdotto la necessità di disporre di una rete integrata di sensori per telerilevamento. In particolare, un sistema di monitoraggio deve soddisfare numerosi requisiti. In primo luogo, esso deve essere geograficamente distribuito. Di conseguenza è opportuno che utilizzi, per quanto possibile, un cablaggio preesistente e tecnologie basate su Internet al fine di consentire un'adeguata scalabilità di rete e facilità di accesso al sistema. Inoltre, esso deve prevedere il supporto di una adeguata varietà di sensori anche di natura diversa, e deve essere facilmente espandibile e riconfigurabile. Infine, deve essere in grado di gestire sia livelli di accesso alle risorse distinti per utenza, tipologia di sensore, politiche di leasing dei dati acquisiti, sia eventi che richiedono interventi rapidi come in situazioni di allarme
Sodium lactate solutions characterization using Electrochemical Impedance Spectroscopy
Full text linkLactate is an important metabolite in human body and, among possible medical applications, it can be used to monitor physical activity. Actually, its concentration represents a clear indication whether optimal training intensity is kept or if muscles are under anaerobic conditions. Routine procedures to measure lactate concentration during physical activity are represented by invasive measurements, which require blood sampling from the patient or the athlete. So, a great advantage would be derived by the possibility to monitor this analyte using non-invasive techniques. Considering the possibility to measure lactate in human sweat during sport activities, this paper presents the characterization of saline aqueous solutions containing sodium lactate by means of Electrochemical Impedance Spectroscopy (EIS). Measurements were performed using a two-electrode electrochemical cell and acquired spectra were analyzed also by means of equivalent electrical circuit (EEC) modeling. Results show an effect due to lactate concentration on solution impedance in the high-frequency region of spectrum, where a change in solution resistance is measured. At the same time, no changes in the measured capacitance were found. Future work will study the electrochemical behavior of lactate solutions also at higher frequencies to further investigate the possible use of EIS for lactate levels monitoring during sport activities
Channel Selection for Optimal EEG Measurement in Motor Imagery-Based Brain-Computer Interfaces
Full text linkA method for selecting electroencephalographic (EEG) signals in motor imagery-based brain-computer interfaces (MI-BCI) is proposed for enhancing the online interoperability and portability of BCI systems, as well as user comfort. The attempt is also to reduce variability and noise of MI-BCI, which could be affected by a large number of EEG channels. The relation between selected channels and MI-BCI performance is therefore analyzed. The proposed method is able to select acquisition channels common to all subjects, while achieving a performance compatible with the use of all the channels. Results are reported with reference to a standard benchmark dataset, the BCI competition IV dataset 2a. They prove that a performance compatible with the best state-of-the-art approaches can be achieved, while adopting a significantly smaller number of channels, both in two and in four tasks classification. In particular, classification accuracy is about 77-83% in binary classification with down to 6 EEG channels, and above 60% for the four-classes case when 10 channels are employed. This gives a contribution in optimizing the EEG measurement while developing non-invasive and wearable MI-based brain-computer interfaces
Environmental monitoring solution for cultural heritage
Full text linkEnvironmental monitoring is crucial factor in the safeguard and conservation of the cultural heritage. Unsuitable environmental conditions can easily accelerate the degradation of several materials and, as consequence, damage the stored artifacts. Moreover, environmental conditions can easily change in an unpredictable way and, therefore, the employment of an environmental monitoring system is mandatory in almost all locations, including museums, storage rooms and outdoor exhibitions. This paper tries to explain the main constraints required for environmental monitoring in the cultural heritage field. Moreover, a novel distributed monitoring system, developed at Politecnico di Torino, is described and compared to several solutions that are commercially available. The proposed solution demonstrated excellent characteristics which satisfy the requirements of environmental monitoring in the cultural heritage at a very competitive cost
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