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关键词： 3D-printing   DLP   FDM   T-Resonator   3D-printed antennas   UHF   RFID  

摘要： In this work, the application in Radiofrequency Identification (RFID) of different additive manufacturing (AM) 3D-printing technologies is discussed. In particular, the well-known Fused Deposition Modeling (FDM) technology is compared with the promising Digital Light Processing (DLP), which is based on the photopolymerization of liquid resins. Based on the research activity of the authors on this topic, a brief introduction to the fundamentals of 3D-printing in electromagnetics as well as to the different applications of both FDM and DLP in realizing Radio Frequency (RF) devices, is firstly given. Then, a comparison of the two technologies is deeply faced. Finally, after evaluated the rugosity of substrates produced with both techniques to verify the potential impact on the design of electromagnetic structures, the two techniques are both exploited for the realization of the dielectric parts of a tunable RFID tag with unconventional shape. It consists of two elements interlinked one each other. The movement between them enables tuning of the resonance frequency as well as the impedance of the antenna. Despite the differences in terms of losses, rugosity, resolution, and dielectric constant, both techniques guaranteed satisfactory values of tag sensitivity, maximum reading range, and tunability. Nevertheless, the careful analysis of the results proposed at the end of the paper suggests how the selection of one technique over the other must be taken considering the specific application constraints.

关键词： Radio Frequency IDentification   Kalman smoother   robot localisation  

摘要： Autonomous vehicles enable the development of smart warehouses and smart factories with an increased visibility, flexibility and efficiency. Thus, effective and affordable localisation methods for indoor vehicles are attracting interest to implement real-time applications. This paper presents an Extended Kalman Smoother design to both localise a mobile agent and reconstruct its entire trajectory through a sensor-fusion employing the UHF-RFID passive technology. Extensive simulations are carried out by considering the smoother optimal-window length and the effect of missing measurements from reference tags. Monte Carlo simulations are conducted for different vehicle trajectories and for different linear and angular velocities to evaluate the method accuracy. Then, an experimental analysis with a unicycle wheeled robot is performed in real indoor scenario, showing a position and orientation root mean square errors of 15 cm, and 0.2 rad, respectively.

关键词： intelligent healthcare   radio frequency identification   rollover sensor  

摘要： This letter proposes an radio frequency identification (RFID)-based bidirectional wireless rollover sensor for intelligent wheelchair. This sensor consists of two symmetric meandered dipole-based RFID tags and a tilt switch. The tilt of the wheelchair can be recognized directly by the chip code received by the RFID reader and no data postprocessing is needed, so it could be used to detect the rollover status and activate rollover protective measures of the intelligent wheelchair. Meanwhile, emergency signal containing the location of the fallen wheelchair can also be sent to the hospitals or aid stations nearby through the RFID reader. A typical application scenario of the sensor has been proposed, modeled, and analyzed. Simulations and measurements of the sensor in this scenario have been carried out to validate its performance.

关键词： Flight range   Meliponiculture   Meliponini   Apidae   Honey   Pollination   Apiculture  

摘要： Bee flight capacity determines the area that a colony can exploit, and this knowledge is essential to formulate management and conservation strategies for each species. In this study, we evaluated the flight capacity of Melipona seminigra using radio frequency identification (RFID). Three questions were addressed: Do the RFID tags affect the flight of M. seminigra workers? What is the effect of the landscape on foraging activity? Does the time since the colony was re-established affect the flight range of foragers? Our results indicate that the RFID tag used does not affect the flight ability of M. seminigra. Bees marked with nontoxic paint vs. RFID tags had the same return ratio and return time to the colony of origin. Flight capacity was affected by the landscape, because the return rate to the colonies was higher from the tested vegetated area than from the sterile area. The time elapsed since the bee colony re-establishment also affected the flight range because the return rate increased with time since the colony was relocated in the new site. We estimate that M. seminigra workers make foraging flights of approximately 1000 m from the colony and that the maximum flight range is 5000 m. Colonies of this species take more than 1 or 2 months to be able to fully exploit a landscape.

关键词： graphene assembly film   RFID tag antenna   high conductivity   flexible   anti-metal  

摘要： We propose a flexible anti-metal radio frequency identification (RFID) tag antenna based on a high-conductivity graphene assembly film (HCGAF). The HCGAF has a conductivity of 1.82 x 10(6) S m(-1), a sheet resistance of 25 m omega and a thickness of 22 mu m. The HCGAF is endowed with high conductivity comparable to metal materials and superb flexibility, which is suitable for making antennas for microwave frequencies. Through proper structural design, parameter optimization, semiautomatic manufacturing and experimental measurements, an HCGAF antenna could realize a realized gain of -7.3 dBi and a radiation efficiency of 80%, and the tag could achieve a 6.4 m read range at 915 MHz on a 20 x 20 cm(2) flat copper plate. In the meantime, by utilizing flexible polyethylene (PE) foam, good conformality was obtained. The read ranges of the tags attached to curved copper plates with different bending radii were measured, as well as those of those attached to several daily objects. All the results demonstrate the excellent performance of the design, which is highly favorable for practical RFID anti-metal applications.

关键词： In-home heathcare   breath monitoring   RFID   Internet of Things  

摘要： Vital signs (e.g., respiration rate or heartbeat rate) sensing is of great importance to implement pervasive in-home healthcare. Traditional vital signs monitoring approaches usually require users to wear some dedicated sensors. These approaches are intrusive and inconvenient to use, especially for elderly people. Some non-intrusive vital signs monitoring approaches based on wireless sensing have been proposed in recent years. However, these approaches require the target user to be in situ during the monitoring process, which greatly limits their utilization in practical scenarios where the target users usually move around. In this paper, we propose RF-RMM, an RFID-based approach to accurate and continuous respiration monitoring for mobile users. The major challenge in respiration monitoring for moving people is that the tiny body displacement caused by the user's respiration is overwhelmed by the user's entire body movement. To address this issue, we propose a novel approach that uses a pair of tags to eliminate the effect of the user's body movement. We fuse the data from the paired tags to cancel the effect of the user's entire body movement and retain only the displacement caused by the user's respiration. Another challenging issue in implementing RF-RMM is how to resolve the phase ambiguity problem when the target user moves around, which becomes more serious than in the static case. We propose a distance tracking algorithm to track the phase transition during the user's movement, according to which the phase ambiguity problem can be well handled. We implement RF-RMM on commercial RFID devices and conduct extensive real-world experiments to evaluate its performance. The results show that RF-RMM achieves accurate respiration rate monitoring with an average error of 0.54 BPM in estimating different users' respiration rate and an average relative error of less than 13% in estimating the user's individual breath length.

关键词： Radiofrequency identification   Location awareness   Antennas   Synthetic aperture radar   Antenna measurements   Reliability   Phase measurement   Holographic   indoor localization   phase differential   synthetic aperture radar (SAR)   ultrahigh-frequency radio frequency identification (UHF RFID)  

摘要： The development of synthetic aperture radar (SAR) radio frequency identification (RFID) localization technology has taken the RFID based indoor localization research to a new level, among which the holographic localization is the most typical approach. Holographic SAR RFID usually performs phase differential to deal with the problem of unknown initial phase. However, problems with regard to the phase differential have emerged in prior literature, some of which make the localization system perform extra but useless efforts, some affect the comprehensibility of the algorithm, and some even reduce the reliability of localization results. Therefore, the analysis of phase differential is very helpful for researchers and practitioners to complete and improve their work. In this paper, several conclusions concerning the phase differential are drawn and analyzed, which are verified by real experiments.

关键词： Implantable antenna   RFID   split ring antenna  

摘要： Wireless intracranial implantable microsystems are believed to potentially innovate the management of brain disorders and the treatment of neurological diseases. The fundamental challenge in the development of the wireless implantable system is the attainment of miniature antennas achieving adequately high efficiency for signaling and wireless power transfer in the presence of the dissipative intracranial tissues. Here, we demonstrate and evaluate an effective approach that utilizes the coupled split rings to develop the miniature implantable antenna. With the proposed approach, the antenna size can be decreased to pi x (3 x 1.5) x1 mm(3) which is less than 2% of the operating wavelength at 915 MHz, while the antenna maintains the gain of -25 dBi when placed 16 mm deep in the anatomical human head model. As a proof of concept, we developed RFID tags based on the proposed antenna and verified their performance with tissue mimicking liquid and in vivo experiment with rats. The measured maximum read range of the tags reaches 0.7 and 1.1 m when immersed 30 mm in the tissue mimicking liquid and implanted 6 mm in a rat's cranial cavity, respectively.

关键词： Facilities management   IFC BIM   RFID   Information management   Maintenance performance  

摘要： Building maintenance includes actions that aim to ensure the components of a building are in acceptable conditions. In traditional maintenance methods, as-built drawings and maintenance manuals are regarded as essential documents for the operation and maintenance of buildings. In this method, the time and cost of facilities management are increased due to managing a large number of documents. Thus, the necessity of creating a range of fields from the information generation to the development of automation systems is evident in the maintenance services from the technological perspective. This research presents a computerized system that integrates the building information model objects in industry foundation classes and radio-frequency identification to improve building maintenance performance. The computerized system is successfully applied to the building of a soccer stadium via the proposed research methodology using a qualitative and practical approach. The main contribution of this research is to provide an innovative framework for the implementation of the proposed system with a step-by-step approach, and also to evaluate the maintenance methods to help different building maintenance stakeholders decide on the appropriate method. The research indicates that with a slight effort on the implementation of the proposed system, a significant improvement of overall maintenance performance can be achieved compared to the traditional method in terms of time, cost, and functionality. It is also hoped that the proposed system can join with other new technologies to promote the system's value in the field of building maintenance.

关键词： Radio frequency identification   Network planning   Constraint satisfaction problem  

摘要： The huge growth of industrial society requires the deployment of radio frequency identification networks on a large scale. This necessitates the installation of a large number of radio frequency identification components (readers, tags, middleware and others). As a consequence, the cost and complexity of networks are increasing due to the large number of readers to be installed. Finding the optimal number, placement and parameters of readers to provide a high quality of service for radio frequency identification systems is a critical problem. A good planning affords a basic need for radio frequency identification networks, such as coverage, load balance and interference between readers. This problem is famous in the literature as a radio frequency identification network planning problem. All the proposed approaches in the literature have been based on meta-heuristics. In this paper, we design a new algorithm, called the RNP-CSP algorithm based on the constraint satisfaction problem framework to solve the radio frequency identification network planning problem. The performance evaluation shows that the RNP-CSP algorithm is more efficient than (PSO)-O-2, GPSO and VNPSO-RNP.