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This paper describes the operating and technical details of the practical implementation of an innovative time domain reflectometry (TDR)-system for monitoring rising damp in building structures. The proposed system employs wire-like, passive, diffused sensing elements (SE’s) that are embedded, at the time of construction or renovation, inside the walls of the building to be monitored. The SE’s remain permanently inside the wall, ready to be interrogated when necessary.

COVID-19 is an ongoing global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Although it primarily attacks the respiratory tract, inflammation can also affect the central nervous system (CNS), leading to chemo-sensory deficits such as anosmia and serious cognitive problems. Recent studies have shown a connection between COVID-19 and neurodegenerative diseases, particularly Alzheimer’s disease (AD). In fact, AD appears to exhibit neurological mechanisms of protein interactions similar to those that occur during COVID-19. Starting from these considerations, this perspective paper outlines a new approach based on the analysis of the complexity of brain signals to identify and quantify common features between COVID-19 and neurodegenerative disorders. Considering the relation between olfactory deficits, AD, and COVID-19, we present an experimental design involving olfactory tasks using multiscale fuzzy entropy (MFE) for electroencephalographic (EEG) signal analysis. Additionally, we present the open challenges and future perspectives. More specifically, the challenges are related to the lack of clinical standards regarding EEG signal entropy and public data that can be exploited in the experimental phase. Furthermore, the integration of EEG analysis with machine learning still requires further investigation.

Type 1 diabetes (T1D) is an autoimmune disease that affects millions of people worldwide. A most challenging aspect regarding diabetes therapy is the way to calculate the insulin bolus amount to inject before meals. The artificial pancreas (AP), combining both blood glucose monitoring and automatic insulin delivery, has demonstrated its effectiveness in T1D treatment. However, one of the limitations of current AP devices is the fact that the patient needs to insert manually the amount of insulin to be released and the bolus is calculated on the estimated carbohydrate intake, while other nutritional factors of the patient's meal are not taken into account. To overcome this issue, in this paper, two innovative algorithms to predict the postprandial blood glucose concentration after the meal in T1D patients on AP systems are presented. The proposed algorithms, which cover a time span of prediction of 180 minutes, take into account not only the carbohydrates amount in the meal but also other selected nutritional factors. More specifically, the proposed algorithms are based on feed forward multi-layer neural networks (FFNNs) and long short-term memory networks (LSTMNs) with a specific hyper-parameter configuration. The output of the proposed architectures consists of a predicted glycemic curve. The algorithms were validated by comparing the predictions of the networks performed on a test dataset with the measured glycemic values recorded by the hybrid closed-loop systems worn by the patients.

Soil monitoring is a key topic from several perspectives, such as moisture level control for irrigation management and anti-contamination purposes. Monitoring the latter is becoming even more important due to increasing environmental pollution. As a direct consequence, there is a strong demand for innovative monitoring systems that are low cost, provide for quasi-real time and in situ monitoring, high sensitivity, and adequate accuracy. Starting from these considerations, this paper addresses the implementation of a microwave reflectometry based-system utilizing a customized bifilar probe and a miniaturized Vector Network Analyzer (m-VNA). The main objective is to relate frequency-domain (FD) measurements to the features of interest, such as the water content and/or the percentage of some polluting substances, through an innovative automatable procedure to retrieve the Debye dielectric parameters of the soil under different conditions. The results from this study confirm the potential of microwave reflectometry for moisture monitoring and contamination detection.

The aim of this work is to propose two different and complementary sensors for the structural health monitoring of concrete beams. In particular, a diffused sensing element and a split ring resonator network are presented. The first sensor is able to detect the variation of the dielectric properties of the concrete along the whole beam length, for a diffuse monitoring both during the important concrete curing phase and also for the entire life cycle of the concrete beams. The resonators instead work punctually, in their surroundings, allowing an accurate evaluation of the permittivity both during the drying phase and after. This allows the continuous monitoring of any presence of water both inside the concrete beam and in points that can be critical, in the case of beams in dams, bridges or in any case subject to a strong presence of water which could lead to deterioration, or worse, cause serious accidents. Moreover, the punctual sensors are able to detect the presence of cracks in the structure and to localize them.

Pest management is looking for green and cost-effective innovative solutions to control tiger mosquitoes and other pests. By using biomimetic principles and biocompatible/biodegradable biopolymers, it could be possible to develop a new approach based on substrates that selectively attract insects by reproducing specific natural environmental conditions and then kill them by hosting and delivering a natural biopesticide or through mechanical action (biomimetic lure and kill approach, BL&K). Such an approach can be theoretically specialized against tiger mosquitoes (BL&K-TM) by designing hydrogels to imitate the natural oviposition site’s conditions to employ them inside a lure and kill ovitraps as a biomimetic oviposition substrate. In this work, the hydrogels have been prepared to prove the concept. The study compares lab/on-field oviposition between standard substrates (absorbing paper/masonite) and a physical and chemically crosslinked hydrogel composition panel. Then the best performing is characterized to evaluate a correlation between the hydrogel’s properties and oviposition. Tests identify a 2-Hydroxyethylcellulose (HEC)-based physical hydrogel preparation as five times more attractive than the control in a lab oviposition assay. When employed on the field in a low-cost cardboard trap, the same substrate is seven times more capturing than a standard masonite ovitrap, with a duration four times longer.

Most sensing networks rely on punctual/local sensors, thus lacking the ability to spatially resolve the quantity-To-be-monitored (e.g., a temperature profile, a humidity profile, etc.) without relying on the deployment of numerous inline sensors. At the state of the art, most quasi-distributed or distributed sensing technologies rely on the use of optical fiber systems; however, these are generally expensive and this limits their large-scale adoption. On the other hand, recently, elongated sensing elements have been successfully used with time-domain reflectometry (TDR) for implementing diffused monitoring solutions. The advantage of TDR is that this is a relatively low-cost technology, with adequate measurement accuracy and the potential to be customized to suit the specific needs of different application contexts of the 4.0 Era. Starting from these considerations, this paper addresses the design, implementation and experimental validation of a novel generation of elongated sensing element networks (SENs) that can be permanently installed in the systems to be monitored and used for obtaining the diffused profile of the quantity-To-be-monitored. In particular, as case studies, three applications are considered: monitoring irrigation process in agriculture (SEN-A, agriculture); leak detection in underground pipes (SEN-W, water); and monitoring of building structures (SEN-B, building).

Measuring moisture content in building materials is essential both for professional practice and for research. However, this is a very complex task, especially when long-term minor destructive measurements are desired. The time-domain reflectometry (TDR) technique is commonly used for soil moisture measurements, but its application in construction materials is considered a relatively new method, particularly for low-porosity building materials. The major obstacles to its current use in construction materials are (1) the difficulty of ensuring good contact between the TDR probe and the material, and (2) the lack of appropriate conversion functions between the measured relative permittivity and the moisture content of building materials. This paper intends to contribute to overcoming these difficulties by explaining in detail all the required steps to monitor moisture content in real-scale limestone walls. For that, a device is presented to guarantee the correct installation of the TDR probes on the walls, and a calibration procedure through the gravimetric method is proposed to avoid the use of an unsuitable calibration function developed for soil moisture measurements. In addition, the importance of the individual probe calibration is discussed, as well as TDR advantages and disadvantages for construction materials. The results obtained so far reveal that the TDR technique is suitable to detect moisture content variations in limestone, which is a low-porosity building material. (c) 2020 by the authors.

It is known that bi-wires can be employed as passive distributed sensing elements (SEs), to accurately locate water infiltrations in soil, concrete materials, and so on, using the standard time-domain reflectometry instrumentation and proper signal processing. This paper examines the possibility of using the same kind of SEs with simpler techniques and cheaper hardware, in order to trigger an alert in the case of water infiltrations. Two techniques are examined: the first measures the SE capacitance, and the second measures the time-of-flight of electromagnetic waves in the SE. The performance of the techniques is comparatively evaluated, in terms of sensitivity to the presence of water and the influence of temperature variations. The capacitance-based technique is found to be more sensitive to the presence of water, but also more prone to the influence of temperature, as long as the temperature variations are of modest entity (below 10 °C). For higher temperature variations, the capacimetric method appears to be advantageous. The results of this paper are useful to practically implement the monitoring of water leaks in a large set of buried pipes, water infiltrations in a large concrete structure, and so on.

In this paper, the most recent advances in the time-domain reflectometry (TDR)-based system for leak-localization in underground pipes are described in detail. More specifically, a new design of sensing element and the use of a new connection modality are proposed. Thanks to these new features, the practical implementation of the system becomes much quicker and its use more effective. Additionally, the present work also describes all the practical aspects and technical details (from installation to functional tests), related to the practical implementation of the system. Finally, to assess the possibility of further increasing the cost-effectiveness of the TDR-based leak localization system, experimental tests were carried out by comparatively using two TDR instruments, differing in specifications and costs, to identify the position of a leak.

In this work, the validation and the practical implementation of a methodology exploiting a time domain reflectometry (TDR)-system for monitoring rising damp in building structures are described in detail. The proposed system employs wire-like, passive, diffused sensing elements (SEs) that are embedded, at the time of construction or renovation, inside the walls of the building to be monitored. The SEs remain permanently inside the wall, ready to be interrogated when necessary. Experimental and simulation results are reported, which demonstrate the possibility of practical implementation and the associated performance in terms of sensitivity.

In this work, the performance of three time domain reflectometry (TDR) instruments (with different hardware architectures, specifications and costs) is comparatively assessed. The goal is to evaluate the performance of low-cost TDR instrumentation, in view of the development of a completely permanent TDR-based monitoring solution, wherein the costs of the instrument is so low, that it can be left on-site, even unguarded, and controlled remotely. Without losing generality, the applications considered for the comparative experiments are the TDR-based detection of leaks in underground pipes and, more in general, of soil water content variations. For this reason, both laboratory and in-the-field experiments are carried out by comparatively using three TDR instruments, in conjunction with wire-like sensing elements (SEs).

The design and the experimental characterization of a waveguide system for complex permittivity measurements on both solid and granular materials are presented. The proposed system is intended for the dielectric characterization of asphalt concrete and of its components at frequencies around 2.45 GHz. Therefore, the system provides measurements on granular materials, such as mineral aggregates found in the asphalt concrete. A series of experimental tests on reference materials shows, via comparison with a standard measurement system, errors within 1%. A theoretical analysis of uncertainty contributions confirms a predicted expanded uncertainty lower than 2%. Furthermore, to test the proposed system for dielectric spectroscopy on materials typical of the asphalt industry, measurements were also performed on calcareous and basaltic materials, which are typically used for the production of asphalt. Finally, three different dielectric models (namely, $\alpha $ model, Ansoult’s model, and Topp’s equation) were comparatively assessed to identify the most suitable ones in describing the water content and dielectric permittivity relationship for the considered materials.

In this paper, the design, the realization, and the experimental characterization of a parallel-plate admittance cell with no guard ring, to be used for low-frequency dielectric permittivity measurements of liquids, are presented. In contrast to guarded-terminal cells, the proposed admittance cell can easily be connected to any LCR meter (even a two-terminal one) employing traditional test fixtures for axial/radial devices. In addition, the fringing effect is compensated for through a correction factor ( $\alpha $ ) obtained from electromagnetic simulations of the structure, rather than through time-consuming experiments on a number of reference liquids or adopting approximated theoretical formulations. Finally, to verify the suitability of the fabricated admittance cell for low-frequency dielectric spectroscopy and to assess its metrological performance, a set of measurements was carried out on six reference nonionic liquid materials. The results show that the accuracy is comparable with the typical measurement accuracy achievable, at much higher costs, when using commercial solutions.

In this work, a novel technological solution for the traceability of hides throughout the leather manufacturing process is addressed. The proposed solution relies on marking the raw hide with a permanent sub-surface tattoo, made with specific substances used as identification markers. In practical applications, the markers can be embedded so as to form a pre-established pattern, thus creating a unique identification code. To experimentally demonstrate the feasibility of the proposed solution, in this work, different types of markers were injected in a raw hide (i.e., prior to its tanning). After the tanning process, the persistence of the markers and of their pattern was verified by comparatively inspecting the hide with two different sensing technologies: microwave reflectometry and X-ray imaging. The obtained results demonstrated that the proposed traceability system is a promising solution to circumvent the age-old problem related to counterfeiting and fraudulent substitutions of raw materials in the leather manufacturing industry.

In this paper, the practical implementation of an innovative time domain reflectometry (TDR)-based system for leak detection in underground water pipes is presented. This system, which had been previously developed and experimented on pilot plants, has now been installed (for the first time) on a large scale, in 10 km of pipes. The present work describes all the practical aspects and technical details (from the design to the functional tests), related to the implementation of the system.

The design and preliminary metrological characterization of a waveguide system for complex permittivity measurement on both compact and granular materials is presented. The proposed system is intended for the dielectric characterization of asphalt concrete and of its components at frequencies around 2.45 GHz. Therefore, the system easily allows performing measurements on granular materials, such as mineral aggregates found in the asphalt concrete. A series of experimental tests on reference materials shows, via comparison with a standard measurement system, errors within 1%. A theoretical analysis of uncertainty contributions confirms a predicted expanded uncertainty lower than 5%.

In this work, the dielectric characterization of pietra gentile (a kind of stone typically found in Cul-tural Heritage structures in Southern Italy) was carried out. Measurements were performed for increasing level of water content of the pietra; thus identifying, empiri-cally, the relation between moisture content and dielec-tric permittivity. The obtained laboratory results can be used to derive moisture content/dielectric permittiv-ity calibration curves that could be used, in practice, for noninvasive on-the-field moisture monitoring of pietra gentile-made Cultural Heritage structures. For exam-ple, it would be possible to use the obtained calibration curves with non-invasive measurement systems, such as time domain reflectometry in conjunction with anten-nas, coaxial probes, or waveguides apertures.

The present work describes two practical application scenarios for an innovative, diffused, low-cost sensing system, which can be permanently embedded in the system to be monitored (STBM), thus allowing the continuous, real-time monitoring over its whole life cycle. The basic idea of the considered sensing system is to endow the STBM with flexible, wire-like sensing elements (SE’s), to be used in conjunction with time domain reflectometry (TDR). One of the crucial advantages of the proposed sensing system is that a SE could be tens of meters long; hence, one single SE may suffice to monitor large areas in a single shot. The two practical applications considered in this paper relate to moisture monitoring of building structures and to the management of irrigation in agriculture: for each of these application fields, preliminary experimental tests were performed, and the potential and limitations of the considered sensing system were assessed. Finally, in order to evaluate the metrological performance of the sensing systems, an additional set of experiments was carried out employing six different types of wire-like SE’s and the obtained results were comparatively assessed.

In this work, an accuracy analysis of the estimation of the time of flight (ToF) for time domain reflectometry (TDR) signals is carried out. For this purpose, three different criteria (referred to as ‘maximum derivative’, ‘zero derivative’, and ‘tangents crossing’) were comparatively applied for the evaluation of the ToF of a TDR signal propagating along a set of RG-58 coaxial cables (with different known length and with known electric parameters). Successively, as a further experimental test, the same criteria were applied on bi-wire cables with unknown electric parameters. Results show that, among the tested criteria, the ‘zero derivative’ criterion provided the best accuracy in the estimation of the ToF.

In this paper, a time-domain reflectrometry (TDR)- based solution for monitoring moisture content in cement-based samples is presented. The proposed system employs a simple flexible biwire, which acts as a distributed sensing element (SE) (as opposed to traditional, local moisture content sensors). Once embedded, the SE remains permanently inside the cement-based sample and can be used both for monitoring the hydration process of the sample structures (ex-ante monitoring) and, successively, for monitoring possible water infiltration during the service life of the structure (ex-post monitoring). In practical applications, the SE could be employed inside building structures at the time of construction, and it could be used for the aforementioned moisture content monitoring purposes. As a preliminary validation of the practical feasibility of the proposed system, in this paper, two cement-based samples (made of mortar and concrete, respectively) were equipped with a SE, and their water content was monitored through TDR measurements, over a 28-day period (thus mimicking the ex-ante monitoring conditions). Furthermore, to verify the potential of the proposed method also for the ex-post monitoring, the air-dried mortar sample was intentionally subjected to wetting conditions and the resulting rising damp was observed through the proposed TDR-based system.

In the present chapter, a global overview of mobile phone sector is presented. Specific focus is given to the Italian mobile phone sector, the sustainability of which is addressed by taking into account two critical aspects related to the behavioral patterns of the users (namely the energy consumption of mobile phones and associated equipment, and the conflicting link between potential dematerialisation due to the miniaturisation of the devices and the resource consumption and waste generated in this sector). This chapter also assesses the impact of the mobile phone sector on the national electricity consumption in a reference year (i.e., 2009), on the growing consumption of resources and on e-waste production. Additionally, some experimental guidelines for evaluating energy consumption and efficiency of mobile phones, of chargers and of batteries are provided. Finally, resource consumption and the e-waste generated by increased mobile phone usage are analyzed.

In this paper, a performance analysis, in terms of accuracy, linearity, and repeatability, of three criteria to estimate the time of flight in time-domain reflectometry (TDR) signals is carried out. In a first set of experiments, the three criteria [referred to as maximum derivative (MD), zero derivative, and tangent crossing (TC)] are applied to TDR signals propagating along a set of coaxial cables, with different known lengths and known electrical parameters. In a second set of experiments, the same criteria are applied to biwire cables in air, with different known lengths and unknown electrical parameters. Finally, in the last set of experiments, the criteria are applied in a more complex situation, i.e., on a biwire used as a sensing element for water-level measurement. The results show that, among the tested criteria, TC appears to provide a very good performance in terms of systematic errors and superior performance in terms of repeatability. The popular MD criterion appears to be more prone to random errors due to noise and TDR artifacts. The results of this paper are relevant to many practical applications of TDR, ranging from fault location in cables to media interface sensing.

This paper deals with the shape of the GPR diffraction curve in dependence of the distance of the measurement line from to the air/soil interface. It will be shown that the diffraction curve changes with respect to the case of data gathered at the air-soil interface, and the calculation of the diffraction curve requires the solution of a fourth degree algebraic equation. The solution in closed form of this equation will be presented, and a physical discussion of the effects of the non-null height of the observation line will be provided.