Active Radio Frequency Identification Research Articles

Planar Thermoelectric Microgenerators in Application to Power RFID Tags.

This paper presents an innovative approach to the integration of thermoelectric microgenerators (μTEGs) based on thick-film thermopiles of planar constantan-silver (CuNi-Ag) and calcium cobaltite oxide-silver (Ca3Co4O9-Ag) thick-film thermopiles with radio frequency identification (RFID) technology. The goal was to consider using the TEG for an active or semi-passive RFID tag. The proposed implementation would allow the communication distance to be increased or even operated without changing batteries. This article discusses the principles of planar thermoelectric microgenerators (μTEGs), focusing on their ability to convert the temperature difference into electrical energy. The concept of integration with active or semi-passive tags is presented, as well as the results of energy efficiency tests, considering various environmental conditions. On the basis of the measurements, the parameters of thermopiles consisting of more thermocouples were simulated to provide the required voltage and power for cooperation with RFID tags. The conclusions of the research indicate promising prospects for the integration of planar thermoelectric microgenerators with RFID technology, opening the way to more sustainable and efficient monitoring and identification systems. Our work provides the theoretical basis and practical experimental data for the further development and implementation of this innovative technology.

A Hybrid Solar-RF Energy Harvesting System Based on an EM4325-Embedded RFID Tag

This paper presents the deployment of a hybrid energy harvesting system that combines a wireless energy harvesting (EH) system and a 6 V, 170 mA monocrystalline solar energy derived from the Sun’s rays. The hybrid energy harvesting (HEH) system comprises the rectifier, the solar cell panel, the charging circuit, and the EM4325 embedded RFID tag. This study aims to design an efficient EH system capable of increasing the read range of an active RFID tag. The proposed approach integrates a meandered line radio frequency identification (RFID) tag with an EM4325 IC chip as the receiver antenna. A halfwave doubler RF rectifier circuit is connected to the antenna using a 50 Ω SMA connector to convert the captured RF waves into usable electrical power. A solar energy charging module equipped with a Maximum Power Point Tracking (MPPT) system, a rechargeable lithium-ion battery, and a DC-DC converter is configured to manage and store the harvested energy efficiently. The UHF tag antenna operates at 919 MHz, achieving a peak gain of 3.54 dB. The proposed rectenna achieves a maximum measured harvested power conversion efficiency (PCE) of 55.14% for an input power (Pin) of 15 dBm at a distance of 5.10 cm, while the solar cell panel realizes 3.92 W of power. Experimental results demonstrate the hybrid harvester system’s effectiveness, achieving a PCE of 86.49% at an output voltage (VDC) of 5.35 V. The main advantage of this approach is the creation of a compact hybrid RF and solar EH system by combining the solar cell panel with the antenna, thus enabling multi-functionality.

Assessment of pebble virtual velocities by combining active RFID fixed stations with geophones

AbstractMonitoring bedload transport in rivers is a challenging research domain teeming with technical innovations and methodological developments aimed at improving our knowledge and models of bedload processes at different spatial–temporal scales. Radio frequency identification (RFID) technology has improved sediment tracking, allowing the characterisation of transport processes of individual particles at flood‐event scales. Meanwhile, geophone sensors have enabled the long‐term continuous monitoring of seismic signals that can provide surrogate measures of bedload fluxes at local scales, during flood events and at sediment‐pulses. The combination of these two techniques could allow sediment transport processes to be linked with both flood events and sediment pulses. In this study, we used a combination of active ultra‐high frequency RFID technology and geophone monitoring stations to link the virtual velocity of tracers with seismic activity, hydraulic forcing, and the properties of the tracked particles. Single and multiple regression models show that seismic activity best explained the observed variance (81%) of the virtual velocity of particles, in comparison with discharge (58%) and stream power (63%). Furthermore, when several control variables (seismic activity and particle properties) were combined in an empirical model, the model explained 89% of the variance and allowed quantification of the portions of the variance explained by hydraulic forcing, geophonic activity and tracked particles. These results show the high potential of these combined monitoring techniques for future in‐field experiments to investigate bedload processes at different spatiotemporal scales in rivers of different morphologies.

SmartCrawler: A Size-Adaptable In-Pipe Wireless Robotic System with Two-Phase Motion Control Algorithm in Water Distribution Systems.

Incidents to pipes cause damage in water distribution systems (WDS) and access to all parts of the WDS is a challenging task. In this paper, we propose an integrated wireless robotic system for in-pipe missions that includes an agile, maneuverable, and size-adaptable (9-in to 22-in) in-pipe robot, "SmartCrawler", with 1.56 m/s maximum speed. We develop a two-phase motion control algorithm that enables reliable motion in straight and rotation in non-straight configurations of in-service WDS. We also propose a bi-directional wireless sensor module based on active radio frequency identification (RFID) working in 434 MHz carrier frequency and 120 kbps for up to 5 sensor measurements to enable wireless underground communication with the burial depth of 1.5 m. The integration of the proposed wireless sensor module and the two-phase motion controller demonstrates promising results for wireless control of the in-pipe robot and multi-parameter sensor transmission for in-pipe missions.

Three-Dimensional Heterogeneous Modeling of a Flexible Lithium-Ion Battery Made From Semi-Solid Electrodes

Abstract Flexible lithium-ion batteries (LIBs) have a strong oncoming consumer market demand for use in wearable electronic devices, flexible smart electronics, roll-up displays, electronic shelf labels, active radio-frequency identification tags, implantable medical devices, and so forth. This market demand necessitates research and development of new flexible LIBs to fulfill the electrical energy and power requirements of these next-generation devices. In this study, we investigate the performance of a new flexible LIB made from semi-solid electrodes. The semi-solid electrodes are made by adding a mixture of electrode active material and conductive material to the organic liquid electrode. This gives dense and viscous slurry so that all solid particles can move by acting pressure, shear, or bending forces to the battery. To study the performance of this battery we develop a 3D heterogeneous mathematical model that considers all necessary transport phenomena including the charge and mass transfer and electrochemical reactions at the continuum mechanics level on the reconstructed 3D structure of semi-solid electrodes. The finite element analysis (FEA) method was used to solve the governing equations using the comsol multiphysics software package. The model is validated using experimental data for the flexible LIB made in the lab. Based on the developed model, several studies are conducted to understand the effect of the battery discharge rate and the operating temperature on the battery capacity. These studies recommend an operational range for the temperature and discharge rate for this flexible LIB.

Application of Internet of Things Combined with Wireless Network Technology in Volleyball Teaching and Training.

Motion information collection technology is a means for measuring, tracking, and recording the movement traces of individuals in space. This method can complete the data collection of volleyball players and the ball trajectory and realize quantification and statistical analysis of the data to present a virtual model of the player's movement trajectory. It is inseparable from the acquisition of information to complete the information collection. Therefore, this work uses the radio frequency identification (RFID) technology in the Internet of Things technology to build an information collection system and apply it to volleyball sports. The existing positioning system based on RFID has problems such as significant positioning errors and high system costs due to the arrangement of a large number of readers. This paper first introduces the theoretical knowledge of the RFID system, wireless network positioning technology, and RFID system positioning method in the Internet of Things. Besides, the theoretical framework of the volleyball movement information acquisition system is presented based on the Received Signal Strength Indication of the RFID system and Location Identification based on the Dynamic Active RFID Calibration (LANDMARC) algorithm. Then, the LANDMARC algorithm is improved through the Centroid Positioning algorithm, forming the CP-LANDMARC algorithm. Finally, a simulation experiment is conducted to test the system effect. The results demonstrate that: (1) the average error of the basic LANDMARC algorithm is 0.55 meters, and the average error of the CP-LANDMARC algorithm is 0.46 meters; (2) the average error of the CP-LANDMARC algorithm is 0.43 meters when the reference label is set to be evenly distributed in a square, and the average error of the optimized algorithm is 0.38 m when the reference label is set as an equilateral triangle; and (3) when the number of reference labels increases to 110, the average error decreases from 0.38 to 0.29. This paper aims to improve the quality of volleyball teaching and training by designing a relevant sports information acquisition system.

Resource limitation drives fission–fusion dynamics of group composition and size in a social bird

Fission–fusion (FF) societies are characterized by frequent changes in group cohesion, composition or size. While the ecological and social drivers of group size are well acknowledged, their effect on FF dynamics is largely unknown, partly due to lack of suitable data sets spanning multiple individuals and spatiotemporal scales. Theory predicts that constraints imposed by local resource availability on group size can yield FF dynamics; yet it has not been applied in contexts other than foraging. In addition, FF dynamics are relatively understudied in nonmammalian vertebrates, although prevalent across taxa. To fill these conceptual and taxonomic gaps we tested predictions arising from current FF theory by tracking multiple Eurasian jackdaws, Coloeus monedula , for two seasons. Using active RFID (radio frequency identification) tags we monitored individual presence/absence over several temporal scales in sites of different ecological functions (nesting, foraging and roosting), and simultaneously quantified local resource availability in these sites. Group size was correlated with resource limitations operating at different ecological contexts and times. Social network analysis revealed remarkably consistent FF patterns which occurred on a diel cycle and changed between seasons, involving changes in group size and composition. Social preferences had a significant influence on FF patterns only during the breeding season and only in nesting and foraging contexts, mainly due to male–female bonds. Our results highlight the importance of ecological context, temporal scale and social preference in avian FF societies and broaden the scope of current theory. • We tracked social birds to study how resource limitation shapes fission-fusion (FF). • Group size was adapted to resource limitation in foraging, nest and roost sites. • Diel movements between sites generated FF, with changes in group size/composition. • Social preferences shaped FF only in the breeding season, in nest/foraging sites. • Findings highlight role of ecological context and social preference in FF societies.

Reconfigurable planar inverted-F antenna for radio frequency identification tag and global positioning system applications

This paper presents the design of a reconfigurable planar inverted-F antenna (PIFA). The proposed antenna is designed and optimized to operate in two frequency bands. 2.4 GHz allocated to the industrial, scientific and medical (ISM) band for the identification of a set of vehicules within a given area, and 1.575 GHz allocated to the global positioning system (GPS) band to locate them outside. The ISM band is used for microwave frequencies for active radio frequency identification (RFID) tag, which is associated with the object to be identified. This antenna consists of two radiating elements connected by a positive-intrinsic-negative (PIN) diode to obtain the frequency reconfigurability. The first radiating element is connected to the ground plane by a shorting pin and excited by a 50 Ω coaxial feed line. Its total size is 30 mm × 50 mm × 7 mm. The substrate used is FR4 with constant dielectric relativity of 4.4 and a height of 1.6 mm. Computer simulation technology microwave studio (CST MWS) software is used to simulate and optimize the proposed reconfigurable PIFA antenna.

In-transit interventions using real-time data in Australian berry supply chains

PurposeThe objective of this paper is to contribute to Australian berry supply chains with a relevant identification regarding the possible data driven interventions that stakeholders can take while the berries are in transit.Design/methodology/approachAn exploratory series of semi-structured interviews was conducted through six Australian experts in the industry with more than 20 years of experience in Australian berry supply chains and the Australian perishable food industry, to identify key possible in-transit interventions that could be implemented in the Australian berry industry.FindingsThe analysis of the interviews revealed a total of 18 possible in-transit interventions. An important finding is that in-transit interventions are made possible by the use of real-time data gathered through IoT devices such as Active Radio Frequency Identification, Time and Temperature Indicators interacting with Wireless Sensor Networks. Another key finding is that Australian berry growers and retailers do possess the technologies and the resources necessary to make in-transit interventions possible, however they have yet applied these technologies to operational decision-making and interventions based on the product, rather focussing on supply chain transactions and events.Research limitations/implicationsSince the research focusses on an Australian context, its findings may or may not be applicable to other countries. The research is exploratory in nature, and its findings should be verified by future research, in particular to test whether the in-transit interventions proposed here can be implemented in a cost-efficient way.Originality/valueTo the authors' knowledge, this publication is the first known academic article to provide a clear understanding of the Australian berry industry from a supply chain and logistics perspective, and the first to explore possible data driven in-transit interventions in perishable food supply chains.

3D Printed RFID Tag Antenna Miniaturized Through Volumetric Folding and Slow-Wave Structures

Radio-frequency identification (RFID) is becoming important with emerging applications for smart cities. RFID Tags are required to be small in size, low in cost and must exhibit as long read range as possible. There is a direct tradeoff between Tag antenna size and its read range. In this work, we study this tradeoff through the use of a relatively higher dielectric constant substrate, volumetric folding, and slow-wave structures (SWS). A 3D antenna design is chosen due to two reasons, 1) it can be folded on a 3D structure, 2), the 3D structure can be used as a package for electronics (in case of active RFID implementation). To enable a low-cost realization, the antenna substrate (package) has been 3D printed with filaments of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\varepsilon }_{r}={5}.{3}$ </tex-math></inline-formula> . A dipole antenna has been folded on this 3D substrate, in a way that the electromagnetic fields radiating from various segments of the antenna do not cancel with each other. Finally, the antenna is loaded with specially designed SWS, whose values have been estimated using artificial transmission line theory. The final antenna design, operating at 866.9 MHz, has a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${ka}$ </tex-math></inline-formula> of 0.26 and demonstrates a radiation efficiency of 32%. The antenna is integrated with a commercial RFID chip (Monza R6) through a silver paste and the measured read range is 2.73 m, while the corrected read range is 4.05 m when the impedance mismatch is considered. Despite being one of the smallest and the lowest cost design (involving 3D printing), the Tag demonstrates one of the highest read range.

The Use of Radio Frequency Identification Technologies for Preventing the Spread of Coronavirus

This article contains description of methods to prevent the spread of coronavirus using modern technologies. Businesses face significant challenges in complying with social distancing guidelines, and they do not have a real understanding of whether these guidelines are followed in their facilities. Many companies use Radio Frequency Identification (RFID) technology to ensure the safety of employees by tracking the proximity or location of each. Kinexon's SafeZone and Triax Proximity Trace are effective solutions to prevent the spread of coronavirus within the enterprise. SafeZone is a unique and powerful active RFID technology, the purpose of which is formation of a warning about the convergence and tracking of contacts in case of a positive test result for COVID-19. The solution consists of UWB labels, worn by employees, as well as cloud software to manage the collected data. Contact information allows companies to take steps to create a safe and healthy work environment. The SafeZone solution uses ultra-wideband (UWB) radio frequency tags. UWB uses the frequency bands 3.25 - 4.75 GHz and 6.25 - 6.75 GHz, which do not overlap with the bands of wireless networks (WLAN) and ISM. RTLS (Real-Time Locating Systems) - an automated system that provides identification, accumulation, processing and storage of information about the location and movement of people, objects, mobile machinery and vehicles to monitor technological and business processes, signaling, as well as for retrospective analysis of certain processes and situations. All RTLS systems consist of several main components: tags, readers and software for interpreting data. Use of active UWB tags in these systems allows to achieve high speeds at a distance of up to 10 m, the technology allows you to reach 110 Mbps. UWB module - a desktop device for setting up and accounting for UWB Tag devices. UWB hub - a device capable of performing thousands of scan scans per second at a distance of up to 30 cm. UWB Sensor - a device that detects pulses emitted by UWB tags and provides the exchange of operational information about resources. UWB reader is an access control device that uses the patented technology of short-pulse ultra-wideband (UWB) signals. UWB-tag - a device that can be attached to objects or clothing of personnel to track and track their location at any time in real time with incredible accuracy. Triax Proximity Trace technology provides active feedback, in the form of visual and audible signal, so people understand when they have violated the proper social distance. Due to Triax Proximity Trace it is possible to determine the degree of contact of employees with those who received a positive test, for example, according to the CDC classification. Components of the system: labels, gateways that are deployed in strategic places, cloud software and information panel for managing proximity event data. Triax Proximity Trace uses tags that operate at 900 MHz. Due to SafeZone and Triax Proximity Trace solutions the company can have a complete picture of potential patients and send for testing real contacts.

Low power ASK modulator based on direct injection‐locked current reuse VCO in 130‐nm CMOS technology for high data rate RFID applications

AbstractA low power consumption Amplitude Shift Keying (ASK) modulator employing current reuse cross‐coupled (CRC) LC‐VCO topology and direct injection locking (IL) technique at 10.5‐GHz frequency is presented in this paper. The modulator consumes 864 μW with a DC supply of 1.2 V drawing an average current of 720 μA. The differential VCO is composed of a PMOS‐NMOS pair in stacked series cross‐coupled connection enabling current reuse which results in reduction of the average current drawn from the power source. For comparison, the ASK modulator is also realized with conventional cross‐coupled (CC) topology using NMOS pair. Both circuit approaches are carried out in GF 130‐nm CMOS technology and the post‐layout simulation results of 0.5 × 0.5 mm2 integrated circuits (ICs) show that the CRC topology consumes less power and half of the average current compared to CC topology. Owing to low power requirements, the CRC ASK modulator can be used in self‐powered active Radio Frequency Identification (RFID) tag transmitters for higher data rates.

434 MHz Environmentally Safe Monitoring Schema for Vehicular Network by AI-ML-IoT Technologies

Connected vehicular tracking schema operated in environmentally safe radio frequency of 434 MHz, artificial intelligence, and machine learning and IoT technology (CVT-AIML-IoT) is cost effective and secured tracking or device monitoring system. The prime benefit of the proposed CVT-AIML-IoT system is that it utilizes cloud internet of things (IoT) technology and active radio frequency identification over global positioning system (GPS), which is prone to attackers due to self-defenseless network architecture. The sliding side of GPS is observed; when the GPS module is switched-off, it can be hidden without any authorization. Hence, an uninterrupted observing secured system like CVT-AIML-IoT is a promising solution with dynamic vehicular PIN generation by AI-ML concept. CVT-AIML-IoT grids the traceable area based on the topographical dependency. Detection range gateway coupled with IoT transceiver module captures data from each tracking zone to the cloud for monitoring over Web UI support and mapped with time stamp. Hence, CVT-AIML-IoT assures vehicular monitoring in a lucrative approach.

Fast tag identification for mobile RFID robots in manufacturing environments

Purpose In manufacturing environments, mobile radio frequency identification (RFID) robots need to quickly identify and collect various types of passive tag and active tag sensor data. The purpose of this paper is to design a robot system compatible with ultra high frequency (UHF) band passive and active RFID applications and to propose a new anti-collision protocol to improve identification efficiency for active tag data collection. Design/methodology/approach A new UHF RFID robot system based on a cloud platform is designed and verified. For the active RFID system, a grouping reservation–based anti-collision algorithm is proposed in which an inventory round is divided into reservation period and polling period. The reservation period is divided into multiple sub-slots. Grouped tags complete sub-slot by randomly transmitting a short reservation frame. Then, in the polling period, the reader accesses each tag by polling. When tags’ reply collision occurs, the reader tries to re-query collided tags once, and the pre-reply tags avoid collisions through random back-off and channel activity detection. Findings The proposed algorithm achieves a maximum theoretical system throughput of about 0.94, and very few tag data frame transmissions overhead. The capture effect and channel activity detection in physical layer can effectively improve system throughput and reduce tag data transmission. Originality/value In this paper, the authors design and verify the UHF band passive and active hybrid RFID robot architecture based on cloud collaboration. And, the proposed anti-collision algorithm would improve active tag data collection speed and reduce tag transmission overhead in complex manufacturing environments.

Design of Attendance Recording System for Pilkades Participants Using Web-Based RFID (E-KTP)

The development of information technology has now been widely used to facilitate, accelerate, and streamline work. The recording system that is still being applied is a type of recording using a manual system using paper media and is inefficient when viewed from a time perspective, recapitulating attendance data and the accuracy or authenticity of the data presented. There is still a frequent habit of voting in the village head elections or not being present at the voting process. Contrary to these problems, this research has developed a recording system using RFID (Radio Frequency Identification) technology. RFID will use sensors to read data. The use of RFID which can make it easier for KPPS officers at TPS. The use of both active and passive RFID technology is able to help record and move data in KPPS, Use of RFID technology, data will be recorded only by passing through a sensor reader on the device, thus the attendance data present by pilkades participants will be stored automatically in storage. So that the attendance of election participants will be easier to do, faster and avoid human error or fraud in the absence of pilkades

An intelligent IoT-based positioning system for theme parks

With the advent of the Internet of Things (IoT) and ubiquitous presence of sensor nodes, positioning technologies have become a topic of interest among researchers. While the applications of positioning systems are very vast, determining the position of moving sensor nodes, finding missing people in large areas, and object tracking are among the most popular ones. The focus of this paper is to propose a positioning system to locate missing people in theme parks. Currently, radio frequency identification (RFID) systems are used in modern theme parks to locate lost visitors. In these systems, a wristband with active RFID tag is given to each visitor and RFID readers are deployed in predetermined locations. When a visitor is in the communication range of a reader, its location can be estimated based on the location of the reader. Therefore, the accuracy of these systems is relevant to the communication range of readers. Another limitation of RFID-based systems is due to the fact that readers cannot be placed in communication range of each other as they can interference with each other. It is clear that the only way to increase the accuracy of such systems is by increasing the number of readers and decreasing the communication range of each reader. In this paper, a Bluetooth low energy (BLE)-based system is proposed to be used in theme parks for locating lost visitors. The advantage of using BLE is due to the fact that it uses frequency hopping spread spectrum (FHSS) thus readers can be placed in communication range of each other without severe interference. In the proposed method, at first, the optimal places for deploying readers are obtained using ant colony optimization (ACO). Then, a fuzzy approach is used to increase the accuracy of the system. Three different signal levels are defined to be used in our fuzzy system based on which the location of visitors can be estimated. By using three levels of signal strength, the accuracy of the system is increased compared with the similar system with the similar number of readers. The simulation results show that the accuracy of the system is improved using this method, and the cost of the system is decreased as BLE readers are much less expensive than their RFID counterparts.

A Dual-Band Low-Power-Consumption Active RFID Tag Based on a Meander FPCB Antenna for Subway Vehicle Management

A meander microstrip antenna was designed to operate in the UHF and microwave bands. Laser direct structuring (LDS) and the flexible printed circuit board (FPCB) method were used to fabricate the antenna, and their results were compared. A dual-band low-power-consumption active radio frequency identification (RFID) tag based on the present antenna was developed and fabricated for an automated subway vehicle maintenance system. The recognition distance of the active tag is more than 20 m at 900 MHz and more than 170 m at 2.4 GHz, while the recognition rate is &gt;95% at 900 MHz and 100% at 2.4 GHz. The 100% recognition rate was obtained when the RFID readers were placed in a line parallel to the subway track. Therefore, we have shown that our active RFID tag can be used in a subway vehicle management system.

A review on wireless sensor technologies

Wireless Sensor Technologies (WST) are entering a new phase. Recent advancements provide enormous possibilities for study and development. This is the result of the lowering costs of ownership, the creation of ever compact sensing devices and the advances in radio frequency technology and digital circuitry. The objective of the current article is to examine the technical and scientific state of the art of wireless sensor technologies and standards for wireless communications in the AgriFood industry. WST in agricultural and food business and to categorize them in suitable categories. These technologies are extremely promising in many areas such as environmental monitoring, precision agriculture, cold chain control or traceability. The article focuses on WSN (Wireless Sensor Networks) and RFID (Radio Frequency Identification), covering the various systems available, current advancements and examples of applications, including ZigBee based WSN and passive, semi-passive and active RFID. Future developments of wireless communications in agricultural and food sector are also addressed.

The potential of Smartstone probes in landslide experiments: how to read motion data

Abstract. Laboratory landslide experiments enable the observation of specific properties of these natural hazards. However, these observations are limited by traditional techniques: frequently used high-speed video analysis and wired sensors (e.g. displacement). These techniques lead to the drawback that either only the surface and 2D profiles can be observed or wires confine the motion behaviour. In contrast, an unconfined observation of the total spatiotemporal dynamics of landslides is needed for an adequate understanding of these natural hazards. The present study introduces an autonomous and wireless probe to characterize motion features of single clasts within laboratory-scale landslides. The Smartstone probe is based on an inertial measurement unit (IMU) and records acceleration and rotation at a sampling rate of 100 Hz. The recording ranges are ±16 g (accelerometer) and ±2000∘ s−1 (gyroscope). The plastic tube housing is 55 mm long with a diameter of 10 mm. The probe is controlled, and data are read out via active radio frequency identification (active RFID) technology. Due to this technique, the probe works under low-power conditions, enabling the use of small button cell batteries and minimizing its size. Using the Smartstone probe, the motion of single clasts (gravel size, median particle diameter d50 of 42 mm) within approx. 520 kg of a uniformly graded pebble material was observed in a laboratory experiment. Single pebbles were equipped with probes and placed embedded and superficially in or on the material. In a first analysis step, the data of one pebble are interpreted qualitatively, allowing for the determination of different transport modes, such as translation, rotation and saltation. In a second step, the motion is quantified by means of derived movement characteristics: the analysed pebble moves mainly in the vertical direction during the first motion phase with a maximal vertical velocity of approx. 1.7 m s−1. A strong acceleration peak of approx. 36 m s−2 is interpreted as a pronounced hit and leads to a complex rotational-motion pattern. In a third step, displacement is derived and amounts to approx. 1.0 m in the vertical direction. The deviation compared to laser distance measurements was approx. −10 %. Furthermore, a full 3D spatiotemporal trajectory of the pebble is reconstructed and visualized supporting the interpretations. Finally, it is demonstrated that multiple pebbles can be analysed simultaneously within one experiment. Compared to other observation methods Smartstone probes allow for the quantification of internal movement characteristics and, consequently, a motion sampling in landslide experiments.

LED Wristbands for Cell-Based Crowd Evacuation: An Adaptive Exit-Choice Guidance System Architecture.

Cell-based crowd evacuation systems provide adaptive or static exit-choice indications that favor a coordinated group dynamic, improving evacuation time and safety. While a great effort has been made to modeling its control logic by assuming an ideal communication and positioning infrastructure, the architectural dimension and the influence of pedestrian positioning uncertainty have been largely overlooked. In our previous research, a cell-based crowd evacuation system (CellEVAC) was proposed that dynamically allocates exit gates to pedestrians in a cell-based pedestrian positioning infrastructure. This system provides optimal exit-choice indications through color-based indications and a control logic module built upon an optimized discrete-choice model. Here, we investigate how location-aware technologies and wearable devices can be used for a realistic deployment of CellEVAC. We consider a simulated real evacuation scenario (Madrid Arena) and propose a system architecture for CellEVAC that includes: a controller node, a radio-controlled light-emitting diode (LED) wristband subsystem, and a cell-node network equipped with active Radio Frequency Identification (RFID) devices. These subsystems coordinate to provide control, display, and positioning capabilities. We quantitatively study the sensitivity of evacuation time and safety to uncertainty in the positioning system. Results showed that CellEVAC was operational within a limited range of positioning uncertainty. Further analyses revealed that reprogramming the control logic module through a simulation optimization process, simulating the positioning system’s expected uncertainty level, improved the CellEVAC performance in scenarios with poor positioning systems.