Permittivity of wood as a function of moisture for cultural heritage applications: A preliminary study

In this work, the evaluation of moisture content in historic wooden objects starting from permittivity measurements is investigated. For this purpose, a WR430 waveguide with a 1.7-2.6 GHz range was used to estimate the complex permittivity correlated to different moisture levels. Experimental tests were carried out on poplar (Populus nigra L.), a wood typically used in central Italy in the thirteenth-sixteenth centuries as a painting support. For the considered measurement system, experimental results and calibration curves are reported

Permittivity-Based Water Content Calibration Measurement in Wood-Based Cultural Heritage: A Preliminary Study

In this work, the dielectric permittivity of four kinds of wood (Fir, Poplar, Oak, and Beech Tree), used in Italian Artworks and structures, was characterized at different humidity levels. Measurements were carried out using three different probes connected to a bench vector network analyzer: a standard WR90 X-band waveguide, a WR430 waveguide, and an open-ended coaxial probe. In particular, we investigated the dispersion model for the four wood species, showing how a log-fit model of the open-ended data presents a determination coefficient R2 > 0.990 in the 1–12 GHz frequency range. This result has proven helpful to fill the frequency gap between the measurements obtained at different water contents with the two waveguide probes showing an R2 > 0.93. Furthermore, correlating the log-fit vertical shift with the water content, it was possible to find a calibration curve with a linear characteristic. These experimental results will be helpful for on-site non-invasive water monitoring of wooden artworks or structures. Moreover, the final results show how the open-ended coaxial probe, with a measurement deviation lower than 7% from the waveguide measurements, may be used directly as a non-invasive sensor for on-site measurements

Poligonales de alta precisión

En Ia década del 70, se estudió y aplicó una estructura de poligonación, denominada de Alta Precisión como extensión de Ia red fundamental de triangulación. Esta estructura, tenía como antecedente que respalda una muy buena calidad, el siatema poligonal, realizado por EE.UU., superponiéndolo sobre su red fundamental en una extensión aproximada de 40.000 km y con el objeto de dar escala a su red satelitaria y controlar su triangulación geodésica de primer orden. Las características de esta estructura, Ios trozos de cadena efectuados, tolerancias fijadas y Ia comparación de costos, son Ios aspectos básicos de este trabajo.In the seventies a traversing structure was studied and epplied. It was caIled of High Accuracy as an extensión of the triangulation fundamental network. This structure had an antecedent which backs a very good quality, the traversing system ρerformed by the U.S., Overimposing it on its fundamental network of an Spproximate Iength of 40*000 km to scale its satellite network snd control its first order geodetic triangulation. The characteristics of this structure, the segmento of chain performed, toIerances set and the cost Comparisons are the basic asρects of this paper.Asociación Argentina de Geofísicos y Geodesta

Pure hydrogen production by steam-iron process. The synergic effect of MnO2 and Fe2O3

In the energy transition from fossil to clean fuels, hydrogen plays a key role. Proton-exchange membrane fuel cells (PEMFCs) represent the most promising hydrogen application, but they require a pure hydrogen stream (CO < 10 ppm). The steam iron process represents a technology for the production of pure H2, exploiting iron redox cycles. If renewable reducing agents are used, the process can be considered completely green. In this context, bio-ethanol can be an interesting solution that is still not thoroughly explored. In this work, the use of ethanol as a reducing agent in the steam iron process will be investigated. Ethanol, at high temperature, decomposes mainly in syngas but can also form coke, which can compromise the process effectiveness, reacting with water and producing CO together with H2. In this work, the deposition of coke is avoided by controlling the duration of the reduction step; in fact, the data demonstrated that coke deposition is significantly dependent on reduction time. Tests were carried out in a fixed bed reactor using hematite (Fe2O3) as raw iron oxide adopting several reduction times (7 minutes-25 minutes), which correspond to different amount of ethanol fed (5 mmolC2H5OH/gFe2O3-17,95 mmolC2H5OH/gFe2O3). The effect of the addition of MnO2 to increase the reduction degree of iron oxides was explored using different amount of MnO2 (10 wt% and 40 wt% with respect to Fe2O3). The tests were performed at fixed temperatures of 675°C and atmospheric pressure. The optimization of the reduction time, in the chosen operating condition, performed only with Fe2O3, shows that, feeding an amount of 5 mmolC2H5OH/gFe2O3, coke deposition is avoided and, therefore, a pure H2 stream in oxidation is obtained. The addition of MnO2 leads to increased H2 yield and process efficiency, confirming its positive effect on the reduction degree of the solid bed. A reaction pathway to demonstrate the synergic effect of Fe2O3 and MnO2 in the reduction step was proposed in this article

A wearable heart rate measurement device for children with autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by early impairment in social and communication domains and autonomic nervous system unbalance. This study evaluated heart rate (HR) as a possible indicator of stress response in children with ASD as compared to children with language disorder (LD). Twenty-four patients [mean age = 42.62 months; SD = 8.14 months,12 with ASD (10 M/2F) and 12 with LD (8 M/4F)] underwent clinical [Leiter International Performance Scale-Revised, Autism Diagnostic Observation Schedule, second edition (ADOS-2)] and physiological evaluation (HR monitoring) during five interactive activities, while wearing an HR measurement device. IQ (ASD:IQ = 103.33 ± 12.85 vs. LD:IQ = 111.00 ± 8.88, p = 0.103) and fluid reasoning on the Leiter-R Scale were within the normal range in all subjects. Increased HR during the third activity (ADOS-2 bubble play) significantly correlated with autistic symptoms (r = 0.415; p = 0.044), while correlations between ADOS-2 total score and HR during the first activity (ADOS-2 free play; r = 0.368; p = 0.077), second activity (Leiter-R figure ground subscale; r = 0.373, p = 0.073), and fifth activity (ADOS-2 anticipation of a routine with objects; r = 0.368; p = 0.076) did not quite reach statistical significance. Applying a linear regression model, we found that the ADOS-2 total score significantly influenced HR variations (p = 0.023). HR monitoring may provide a better understanding of the stress-provoking situations for children with ASD. Furthermore, it could help clinicians detect the impact of the stressful condition on the autistic core and adress treatment strategy

Stima del contenuto di acqua nelle pietre ornamentali tramite riflettometria a microonde

Negli ultimi anni, l’interesse della comunità scientifica per il monitoraggio e la conservazione del patrimonio culturale è aumentato significativamente. Dal momento che l’eccesso di umidità può avere effetti indesiderabili sui materiali storici, sono state utilizzate numerose tecniche di misura per rilevare la presenza di umidità o la salinità, come la risonanza magnetica, il ground penetrating radar, la tomografia a resistenza elettrica o la termografia a infrarossi. L’utilizzo di queste tecniche richiede competenze specifiche da parte dell’operatore. Il sistema di misura proposto in questo lavoro è basato sulla riflettometria a microonde, non invasiva e di facile uso. In particolare, un risonatore a patch e un analizzatore di reti vettoriale sono stati impiegati per la caratterizzazione del contenuto di umidità in due tipi di pietre: leccese e gentile

Tetrapolar Low-Cost Systems for Thoracic Impedance Plethysmography

Bioelectrical impedance analysis applied to the pneumographic investigation is a technique for monitoring the breathing activity through the measurement of variations in the trans-thoracic electrical impedance. In this paper we present, a low-cost re-configurable measurement system. The system is based on a 4-electrode voltamperometric technique and a network of inertial sensors for correction of arms motion artifacts. The trans-thoracic impedance is acquired via an ad hoc programmed LabVIEW software. A correction algorithm, based on the correlation between the acquired signal and the motion artifact, is proposed. A preliminary metrological assessment of the system is performed to evaluate the accuracy and sensitivity of patient breath monitoring. Results show a high accuracy in a 100 Ω range of measurement. The proposed algorithm allows for the estimation of the thoracic impedance with a maximum error of 30% and to neglect the phase shift between the breath and the movement signals

Accuracy evaluation of an ECG device for heart failure patients self-monitoring: a preliminary study

Nowadays, wearable wireless devices represent an exciting challenge both for controlling one's lifestyle and for specific applications like telemedicine and at-home healthcare monitoring. Many low-cost sensors and sensor systems are currently on the market, but only a limited number of them are validated and certified for clinical applications. This paper presents preliminary results of the accuracy assessment of an electrocardiography (ECG) device for cardiovascular disease monitoring that will be applied by the patients for self-checking. In particular, the analog front end integrated circuit MAX30001 is proposed and tested, while the principal features of MAX30001 evaluation board software were described, as well as three cardiac pathologies which require in-depth and continuous ECG monitoring. An accuracy setup was realized to evaluate the acquisition fidelity; it is based on a high-quality waveform generator that imposes to the MAX30001 two different periodic signals: a sine and a sinc with the frequency of 1 Hz to 10 Hz with a 5 Hz step. The accuracy evaluation shows how the integrated circuit provides a normalized root mean square error in the chosen frequency range, lower than 0.01 and lower than 0.20, respectively, for the sine and sinc waveform. Moreover, it presents for sinc signal a peak detection rate of 80%

Compensating for Density Effect in Permittivity-Based Moisture Content Measurements on Historic Masonry Materials

Dielectric permittivity-based measurement techniques are establishing themselves as attractive solutions for assessing moisture content of historic masonry materials. The relative simplicity of the measurement principle and the inherent adaptability to diverse operating conditions are two of the most notable features of these techniques. In spite of these specific advantages, however, there are still some aspects that hinder the widespread use of permittivity-based moisture content measurement systems, and make their standardization difficult. In particular, the density of the sample under test may affect the estimation of permittivity, thus possibly leading to inaccurate moisture content measurements. As a result, the measurement system should be re-calibrated even when the same type of material is being investigated (e.g., two samples of the same type of stone, but extracted from different quarries).To circumvent this problem and to fully exploit the potential of permittivity-based moisture content measurements, in this work, a strategy for compensating for the effect of density is addressed. In order to verify the suitability of this strategy, moisture content measurements were carried out on samples of two type of stones typical of historic masonry, namely gentile stone and red-clay brick