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Sensors, Volume 14, Issue 1 (January 2014), Pages 1-1901

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Open AccessEditorial Sensors Best Paper Award 2014
Sensors 2014, 14(1), 1898-1901; https://doi.org/10.3390/s140101898
Received: 20 January 2014 / Accepted: 23 January 2014 / Published: 23 January 2014
Cited by 1 | PDF Full-text (91 KB) | HTML Full-text | XML Full-text
Abstract
In 2011, an annual award system was instituted to recognize outstanding Sensors papers that are related to sensing technologies and applications and meet the aims, scope and high standards of this journal [1–3]. This year, nominations were made by the Section Editor-in-Chiefs of
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In 2011, an annual award system was instituted to recognize outstanding Sensors papers that are related to sensing technologies and applications and meet the aims, scope and high standards of this journal [1–3]. This year, nominations were made by the Section Editor-in-Chiefs of Sensors from among all the papers published in 2010 to track citations. Reviews and full research articles were considered separately. [...] Full article
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Open AccessArticle A Secure Trust Establishment Scheme for Wireless Sensor Networks
Sensors 2014, 14(1), 1877-1897; https://doi.org/10.3390/s140101877
Received: 14 October 2013 / Revised: 10 January 2014 / Accepted: 15 January 2014 / Published: 22 January 2014
Cited by 11 | PDF Full-text (513 KB) | HTML Full-text | XML Full-text
Abstract
Trust establishment is an important tool to improve cooperation and enhance security in wireless sensor networks. The core of trust establishment is trust estimation. If a trust estimation method is not robust against attack and misbehavior, the trust values produced will be meaningless,
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Trust establishment is an important tool to improve cooperation and enhance security in wireless sensor networks. The core of trust establishment is trust estimation. If a trust estimation method is not robust against attack and misbehavior, the trust values produced will be meaningless, and system performance will be degraded. We present a novel trust estimation method that is robust against on-off attacks and persistent malicious behavior. Moreover, in order to aggregate recommendations securely, we propose using a modified one-step M-estimator scheme. The novelty of the proposed scheme arises from combining past misbehavior with current status in a comprehensive way. Specifically, we introduce an aggregated misbehavior component in trust estimation, which assists in detecting an on-off attack and persistent malicious behavior. In order to determine the current status of the node, we employ previous trust values and current measured misbehavior components. These components are combined to obtain a robust trust value. Theoretical analyses and evaluation results show that our scheme performs better than other trust schemes in terms of detecting an on-off attack and persistent misbehavior. Full article
(This article belongs to the Section Sensor Networks)
Open AccessArticle A Spatial Division Clustering Method and Low Dimensional Feature Extraction Technique Based Indoor Positioning System
Sensors 2014, 14(1), 1850-1876; https://doi.org/10.3390/s140101850
Received: 26 December 2013 / Revised: 14 January 2014 / Accepted: 20 January 2014 / Published: 22 January 2014
Cited by 9 | PDF Full-text (1084 KB) | HTML Full-text | XML Full-text
Abstract
Indoor positioning systems based on the fingerprint method are widely used due to the large number of existing devices with a wide range of coverage. However, extensive positioning regions with a massive fingerprint database may cause high computational complexity and error margins, therefore
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Indoor positioning systems based on the fingerprint method are widely used due to the large number of existing devices with a wide range of coverage. However, extensive positioning regions with a massive fingerprint database may cause high computational complexity and error margins, therefore clustering methods are widely applied as a solution. However, traditional clustering methods in positioning systems can only measure the similarity of the Received Signal Strength without being concerned with the continuity of physical coordinates. Besides, outage of access points could result in asymmetric matching problems which severely affect the fine positioning procedure. To solve these issues, in this paper we propose a positioning system based on the Spatial Division Clustering (SDC) method for clustering the fingerprint dataset subject to physical distance constraints. With the Genetic Algorithm and Support Vector Machine techniques, SDC can achieve higher coarse positioning accuracy than traditional clustering algorithms. In terms of fine localization, based on the Kernel Principal Component Analysis method, the proposed positioning system outperforms its counterparts based on other feature extraction methods in low dimensionality. Apart from balancing online matching computational burden, the new positioning system exhibits advantageous performance on radio map clustering, and also shows better robustness and adaptability in the asymmetric matching problem aspect. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Markov Jump Linear Systems-Based Position Estimation for Lower Limb Exoskeletons
Sensors 2014, 14(1), 1835-1849; https://doi.org/10.3390/s140101835
Received: 10 December 2013 / Revised: 16 January 2014 / Accepted: 17 January 2014 / Published: 22 January 2014
Cited by 7 | PDF Full-text (1531 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we deal with Markov Jump Linear Systems-based filtering applied to robotic rehabilitation. The angular positions of an impedance-controlled exoskeleton, designed to help stroke and spinal cord injured patients during walking rehabilitation, are estimated. Standard position estimate approaches adopt Kalman filters
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In this paper, we deal with Markov Jump Linear Systems-based filtering applied to robotic rehabilitation. The angular positions of an impedance-controlled exoskeleton, designed to help stroke and spinal cord injured patients during walking rehabilitation, are estimated. Standard position estimate approaches adopt Kalman filters (KF) to improve the performance of inertial measurement units (IMUs) based on individual link configurations. Consequently, for a multi-body system, like a lower limb exoskeleton, the inertial measurements of one link (e.g., the shank) are not taken into account in other link position estimation (e.g., the foot). In this paper, we propose a collective modeling of all inertial sensors attached to the exoskeleton, combining them in a Markovian estimation model in order to get the best information from each sensor. In order to demonstrate the effectiveness of our approach, simulation results regarding a set of human footsteps, with four IMUs and three encoders attached to the lower limb exoskeleton, are presented. A comparative study between the Markovian estimation system and the standard one is performed considering a wide range of parametric uncertainties. Full article
(This article belongs to the Special Issue Wearable Gait Sensors)
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Open AccessArticle Thermal Balance Analysis of a Micro-Thermoelectric Gas Sensor Using Catalytic Combustion of Hydrogen
Sensors 2014, 14(1), 1822-1834; https://doi.org/10.3390/s140101822
Received: 16 December 2013 / Revised: 13 January 2014 / Accepted: 14 January 2014 / Published: 21 January 2014
Cited by 4 | PDF Full-text (868 KB) | HTML Full-text | XML Full-text
Abstract
A thermoelectric gas sensor (TGS) with a combustion catalyst is a calorimetric sensor that changes the small heat of catalytic combustion into a signal voltage. We analyzed the thermal balance of a TGS to quantitatively estimate the sensor parameters. The voltage signal of
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A thermoelectric gas sensor (TGS) with a combustion catalyst is a calorimetric sensor that changes the small heat of catalytic combustion into a signal voltage. We analyzed the thermal balance of a TGS to quantitatively estimate the sensor parameters. The voltage signal of a TGS was simulated, and the heat balance was calculated at two sections across the thermoelectric film of a TGS. The thermal resistances in the two sections were estimated from the thermal time constants of the experimental signal curves of the TGS. The catalytic combustion heat Qcatalyst required for 1 mV of ∆Vgas was calculated to be 46.1 μW. Using these parameters, we find from simulations for the device performance that the expected Qcatalyst for 200 and 1,000 ppm H2 was 3.69 μW and 11.7 μW, respectively. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Applicability of Time-Averaged Holography for Micro-Electro-Mechanical System Performing Non-Linear Oscillations
Sensors 2014, 14(1), 1805-1821; https://doi.org/10.3390/s140101805
Received: 4 December 2013 / Revised: 13 January 2014 / Accepted: 13 January 2014 / Published: 21 January 2014
Cited by 6 | PDF Full-text (1079 KB) | HTML Full-text | XML Full-text
Abstract
Optical investigation of movable microsystem components using time-averaged holography is investigated in this paper. It is shown that even a harmonic excitation of a non-linear microsystem may result in an unpredictable chaotic motion. Analytical results between parameters of the chaotic oscillations and the
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Optical investigation of movable microsystem components using time-averaged holography is investigated in this paper. It is shown that even a harmonic excitation of a non-linear microsystem may result in an unpredictable chaotic motion. Analytical results between parameters of the chaotic oscillations and the formation of time-averaged fringes provide a deeper insight into computational and experimental interpretation of time-averaged MEMS holograms. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Control Framework for Dexterous Manipulation Using Dynamic Visual Servoing and Tactile Sensors’ Feedback
Sensors 2014, 14(1), 1787-1804; https://doi.org/10.3390/s140101787
Received: 16 December 2013 / Revised: 10 January 2014 / Accepted: 15 January 2014 / Published: 21 January 2014
Cited by 11 | PDF Full-text (654 KB) | HTML Full-text | XML Full-text
Abstract
Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits the
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Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits the definition of new visual controllers which allow the path tracking of the object motion taking into account both the dynamics model of the robot hand and the grasping force of the fingertips under a hybrid control scheme. In addition, the proposed general method employs optimal control to obtain the desired behaviour in the joint space of the fingers based on an indicated cost function which determines how the control effort is distributed over the joints of the robotic hand. Finally, authors show experimental verifications on a real robotic manipulation system for some of the controllers derived from the control framework. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Estimating the Concentration and Biodegradability of Organic Matter in 22 Wastewater Treatment Plants Using Fluorescence Excitation Emission Matrices and Parallel Factor Analysis
Sensors 2014, 14(1), 1771-1786; https://doi.org/10.3390/s140101771
Received: 25 November 2013 / Revised: 4 January 2014 / Accepted: 15 January 2014 / Published: 20 January 2014
Cited by 35 | PDF Full-text (509 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This study aimed at monitoring the changes of fluorescent components in wastewater samples from 22 Korean biological wastewater treatment plants and exploring their prediction capabilities for total organic carbon (TOC), dissolved organic carbon (DOC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and
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This study aimed at monitoring the changes of fluorescent components in wastewater samples from 22 Korean biological wastewater treatment plants and exploring their prediction capabilities for total organic carbon (TOC), dissolved organic carbon (DOC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and the biodegradability of the wastewater using an optical sensing technique based on fluorescence excitation emission matrices and parallel factor analysis (EEM-PARAFAC). Three fluorescent components were identified from the samples by using EEM-PARAFAC, including protein-like (C1), fulvic-like (C2) and humic-like (C3) components. C1 showed the highest removal efficiencies for all the treatment types investigated here (69% ± 26%–81% ± 8%), followed by C2 (37% ± 27%–65% ± 35%), while humic-like component (i.e., C3) tended to be accumulated during the biological treatment processes. The percentage of C1 in total fluorescence (%C1) decreased from 54% ± 8% in the influents to 28% ± 8% in the effluents, while those of C2 and C3 (%C2 and %C3) increased from 43% ± 6% to 62% ± 9% and from 3% ± 7% to 10% ± 8%, respectively. The concentrations of TOC, DOC, BOD, and COD were the most correlated with the fluorescence intensity (Fmax) of C1 (r = 0.790–0.817), as compared with the other two fluorescent components. The prediction capability of C1 for TOC, BOD, and COD were improved by using multiple regression based on Fmax of C1 and suspended solids (SS) (r = 0.856–0.865), both of which can be easily monitored in situ. The biodegradability of organic matter in BOD/COD were significantly correlated with each PARAFAC component and their combinations (r = −0.598–0.613, p < 0.001), with the highest correlation coefficient shown for %C1. The estimation capability was further enhanced by using multiple regressions based on %C1, %C2 and C3/C2 (r = −0.691). Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Two-Stage System Based on a Software-Defined Radio for Stabilizing of Optical Frequency Combs in Long-Term Experiments
Sensors 2014, 14(1), 1757-1770; https://doi.org/10.3390/s140101757
Received: 30 October 2013 / Revised: 8 January 2014 / Accepted: 8 January 2014 / Published: 20 January 2014
Cited by 8 | PDF Full-text (1434 KB) | HTML Full-text | XML Full-text
Abstract
A passive optical resonator is a special sensor used for measurement of lengths on the nanometer and sub-nanometer scale. A stabilized optical frequency comb can provide an ultimate reference for measuring the wavelength of a tunable laser locked to the optical resonator. If
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A passive optical resonator is a special sensor used for measurement of lengths on the nanometer and sub-nanometer scale. A stabilized optical frequency comb can provide an ultimate reference for measuring the wavelength of a tunable laser locked to the optical resonator. If we lock the repetition and offset frequencies of the comb to a high-grade radiofrequency (RF) oscillator its relative frequency stability is transferred from the RF to the optical frequency domain. Experiments in the field of precise length metrology of low-expansion materials are usually of long-term nature so it is required that the optical frequency comb stay in operation for an extended period of time. The optoelectronic closed-loop systems used for stabilization of combs are usually based on traditional analog electronic circuits processing signals from photodetectors. From an experimental point of view, these setups are very complicated and sensitive to ambient conditions, especially in the optical part, therefore maintaining long-time operation is not easy. The research presented in this paper deals with a novel approach based on digital signal processing and a software-defined radio. We describe digital signal processing algorithms intended for keeping the femtosecond optical comb in a long-time stable operation. This need arose during specialized experiments involving measurements of optical frequencies of tunable continuous-wave lasers. The resulting system is capable of keeping the comb in lock for an extensive period of time (8 days or more) with the relative stability better than 1.6 × 10−11. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Modeling and Characterization of the Implant Intra-Body Communication Based on Capacitive Coupling Using a Transfer Function Method
Sensors 2014, 14(1), 1740-1756; https://doi.org/10.3390/s140101740
Received: 23 October 2013 / Revised: 7 January 2014 / Accepted: 16 January 2014 / Published: 20 January 2014
Cited by 10 | PDF Full-text (445 KB) | HTML Full-text | XML Full-text
Abstract
Implantable devices have important applications in biomedical sensor networks used for biomedical monitoring, diagnosis and treatment, etc. In this paper, an implant intra-body communication (IBC) method based on capacitive coupling has been proposed, and the modeling and characterization of this kind of
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Implantable devices have important applications in biomedical sensor networks used for biomedical monitoring, diagnosis and treatment, etc. In this paper, an implant intra-body communication (IBC) method based on capacitive coupling has been proposed, and the modeling and characterization of this kind of IBC has been investigated. Firstly, the transfer function of the implant IBC based on capacitive coupling was derived. Secondly, the corresponding parameters of the transfer function are discussed. Finally, both measurements and simulations based on the proposed transfer function were carried out, while some important conclusions have been achieved, which indicate that the achieved transfer function and conclusions are able to help to achieve an implant communication method with the highly desirable characteristics of low power consumption, high data rate, high transmission quality, etc. Full article
(This article belongs to the Special Issue Biomedical Sensors and Systems)
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Open AccessArticle The Control of Tendon-Driven Dexterous Hands with Joint Simulation
Sensors 2014, 14(1), 1723-1739; https://doi.org/10.3390/s140101723
Received: 7 December 2013 / Revised: 3 January 2014 / Accepted: 6 January 2014 / Published: 20 January 2014
Cited by 3 | PDF Full-text (754 KB) | HTML Full-text | XML Full-text
Abstract
An adaptive impedance control algorithm for tendon-driven dexterous hands is presented. The main idea of this algorithm is to compensate the output of the classical impedance control by an offset that is a proportion-integration-differentiation (PID) expression of force error. The adaptive impedance control
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An adaptive impedance control algorithm for tendon-driven dexterous hands is presented. The main idea of this algorithm is to compensate the output of the classical impedance control by an offset that is a proportion-integration-differentiation (PID) expression of force error. The adaptive impedance control can adjust the impedance parameters indirectly when the environment position and stiffness are uncertain. In addition, the position controller and inverse kinematics solver are specially designed for the tendon-driven hand. The performance of the proposed control algorithm is validated by using MATLAB and ADAMS software for joint simulation. ADAMS is a great software for virtual prototype analysis. A tendon-driven hand model is built and a control module is generated in ADAMS. Then the control system is built in MATLAB using the control module. The joint simulation results demonstrate fast response and robustness of the algorithm when the environment is not exactly known, so the algorithm is suitable for the control of tendon-driven dexterous hands. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Wearable Gait Measurement System with an Instrumented Cane for Exoskeleton Control
Sensors 2014, 14(1), 1705-1722; https://doi.org/10.3390/s140101705
Received: 15 November 2013 / Revised: 31 December 2013 / Accepted: 31 December 2013 / Published: 17 January 2014
Cited by 31 | PDF Full-text (1703 KB) | HTML Full-text | XML Full-text
Abstract
In this research we introduce a wearable sensory system for motion intention estimation and control of exoskeleton robot. The system comprises wearable inertial motion sensors and shoe-embedded force sensors. The system utilizes an instrumented cane as a part of the interface between the
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In this research we introduce a wearable sensory system for motion intention estimation and control of exoskeleton robot. The system comprises wearable inertial motion sensors and shoe-embedded force sensors. The system utilizes an instrumented cane as a part of the interface between the user and the robot. The cane reflects the motion of upper limbs, and is used in terms of human inter-limb synergies. The developed control system provides assisted motion in coherence with the motion of other unassisted limbs. The system utilizes the instrumented cane together with body worn sensors, and provides assistance for start, stop and continuous walking. We verified the function of the proposed method and the developed wearable system through gait trials on treadmill and on ground. The achievement contributes to finding an intuitive and feasible interface between human and robot through wearable gait sensors for practical use of assistive technology. It also contributes to the technology for cognitively assisted locomotion, which helps the locomotion of physically challenged people. Full article
(This article belongs to the Special Issue Wearable Gait Sensors)
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Open AccessArticle Wireless Displacement Sensing Enabled by Metamaterial Probes for Remote Structural Health Monitoring
Sensors 2014, 14(1), 1691-1704; https://doi.org/10.3390/s140101691
Received: 29 October 2013 / Revised: 11 December 2013 / Accepted: 9 January 2014 / Published: 17 January 2014
Cited by 16 | PDF Full-text (919 KB) | HTML Full-text | XML Full-text
Abstract
We propose and demonstrate a wireless, passive, metamaterial-based sensor that allows for remotely monitoring submicron displacements over millimeter ranges. The sensor comprises a probe made of multiple nested split ring resonators (NSRRs) in a double-comb architecture coupled to an external antenna in its
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We propose and demonstrate a wireless, passive, metamaterial-based sensor that allows for remotely monitoring submicron displacements over millimeter ranges. The sensor comprises a probe made of multiple nested split ring resonators (NSRRs) in a double-comb architecture coupled to an external antenna in its near-field. In operation, the sensor detects displacement of a structure onto which the NSRR probe is attached by telemetrically tracking the shift in its local frequency peaks. Owing to the NSRR’s near-field excitation response, which is highly sensitive to the displaced comb-teeth over a wide separation, the wireless sensing system exhibits a relatively high resolution (<1 µm) and a large dynamic range (over 7 mm), along with high levels of linearity (R2 > 0.99 over 5 mm) and sensitivity (>12.7 MHz/mm in the 1–3 mm range). The sensor is also shown to be working in the linear region in a scenario where it is attached to a standard structural reinforcing bar. Because of its wireless and passive nature, together with its low cost, the proposed system enabled by the metamaterial probes holds a great promise for applications in remote structural health monitoring. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Manufacture of Radio Frequency Micromachined Switches with Annealing
Sensors 2014, 14(1), 1680-1690; https://doi.org/10.3390/s140101680
Received: 30 October 2013 / Revised: 27 December 2013 / Accepted: 8 January 2014 / Published: 17 January 2014
PDF Full-text (851 KB) | HTML Full-text | XML Full-text
Abstract
The fabrication and characterization of a radio frequency (RF) micromachined switch with annealing were presented. The structure of the RF switch consists of a membrane, coplanar waveguide (CPW) lines, and eight springs. The RF switch is manufactured using the complementary metal oxide semiconductor
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The fabrication and characterization of a radio frequency (RF) micromachined switch with annealing were presented. The structure of the RF switch consists of a membrane, coplanar waveguide (CPW) lines, and eight springs. The RF switch is manufactured using the complementary metal oxide semiconductor (CMOS) process. The switch requires a post-process to release the membrane and springs. The post-process uses a wet etching to remove the sacrificial silicon dioxide layer, and to obtain the suspended structures of the switch. In order to improve the residual stress of the switch, an annealing process is applied to the switch, and the membrane obtains an excellent flatness. The finite element method (FEM) software CoventorWare is utilized to simulate the stress and displacement of the RF switch. Experimental results show that the RF switch has an insertion loss of 0.9 dB at 35 GHz and an isolation of 21 dB at 39 GHz. The actuation voltage of the switch is 14 V. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering 2013)
Open AccessArticle Statistical Tools Applied in the Characterisation and Evaluation of a Thermo-Hygrometric Corrective Action Carried out at the Noheda Archaeological Site (Noheda, Spain)
Sensors 2014, 14(1), 1665-1679; https://doi.org/10.3390/s140101665
Received: 10 November 2013 / Revised: 24 December 2013 / Accepted: 9 January 2014 / Published: 17 January 2014
Cited by 2 | PDF Full-text (906 KB) | HTML Full-text | XML Full-text
Abstract
The Noheda archaeological site is unique and exceptional for its size, and the quality and conservation condition of the Roman mosaic pavement covering its urban pars. In 2008 a tent was installed as protection from rain and sun. Being of interest to
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The Noheda archaeological site is unique and exceptional for its size, and the quality and conservation condition of the Roman mosaic pavement covering its urban pars. In 2008 a tent was installed as protection from rain and sun. Being of interest to characterise the microclimate of the remains, six probes with relative humidity and temperature sensors were installed in 2013 for this purpose. Microclimate monitoring allowed us to check relative humidity differences resulting from the groundwater level, as well as inner sensors reaching maximum temperatures higher than the outdoors ones as a consequence of the non-ventilated tent covering the archaeological site. Microclimatic conditions in the archaeological site were deemed detrimental for the conservation of the mosaics. Thus, in summer 2013, expanded clay and geotextile were installed over the mosaics as a corrective action. The outcomes of this study have proven the effectiveness of this solution to control temperature and relative humidity, helping to configure a more stable microclimate suitable for preservation of the mosaic. Full article
(This article belongs to the Special Issue Sensors for Cultural Heritage Diagnostics)
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