Optimization of multichip RFID tag antenna with genetic algorithm and method of moments

A specific procedure is implemented for the optimization of passive part of multichip RFID tag antenna, based on the performance parameter in terms of newly developed concepts. Examples are given and significant improvements have been observed comparing with previous results, which verifies the approach

The weekend effect on the provision of Emergency Surgery before and during the COVID-19 pandemic: case–control analysis of a retrospective multicentre database

Introduction: The concept of “weekend effect”, that is, substandard healthcare during weekends, has never been fully demonstrated, and the different outcomes of emergency surgical patients admitted during weekends may be due to different conditions at admission and/or different therapeutic approaches. Aim of this international audit was to identify any change of pattern of emergency surgical admissions and treatments during weekends. Furthermore, we aimed at investigating the impact of the COVID-19 pandemic on the alleged “weekend effect”. Methods: The database of the CovidICE-International Study was interrogated, and 6263 patients were selected for analysis. Non-trauma, 18+ yo patients admitted to 45 emergency surgery units in Europe in the months of March–April 2019 and March–April 2020 were included. Demographic and clinical data were anonymised by the referring centre and centrally collected and analysed with a statistical package. This study was endorsed by the Association of Italian Hospital Surgeons (ACOI) and the World Society of Emergency Surgery (WSES). Results: Three-quarters of patients have been admitted during workdays and only 25.7% during weekends. There was no difference in the distribution of gender, age, ASA class and diagnosis during weekends with respect to workdays. The first wave of the COVID pandemic caused a one-third reduction of emergency surgical admission both during workdays and weekends but did not change the relation between workdays and weekends. The treatment was more often surgical for patients admitted during weekends, with no difference between 2019 and 2020, and procedures were more often performed by open surgery. However, patients admitted during weekends had a threefold increased risk of laparoscopy-to-laparotomy conversion (1% vs. 3.4%). Hospital stay was longer in patients admitted during weekends, but those patients had a lower risk of readmission. There was no difference of the rate of rescue surgery between weekends and workdays. Subgroup analysis revealed that interventional procedures for hot gallbladder were less frequently performed on patients admitted during weekends. Conclusions: Our analysis revealed that demographic and clinical profiles of patients admitted during weekends do not differ significantly from workdays, but the therapeutic strategy may be different probably due to lack of availability of services and skillsets during weekends. The first wave of the COVID-19 pandemic did not impact on this difference

Advances in Vehicular Ad-hoc Networks (VANETs): challenges and road-map for future development

Recent advances in wireless communication technologies and auto-mobile industry have triggered a significant research interest in the field of vehicular ad-hoc networks (VANETs) over the past few years. A vehicular network consists of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications supported by wireless access technologies such as IEEE 802.11p. This innovation in wireless communication has been envisaged to improve road safety and motor traffic efficiency in near future through the development of intelligent transportation system (ITS). Hence, governments, auto-mobile industries and academia are heavily partnering through several ongoing research projects to establish standards for VANETs. The typical set of VANET application areas, such as vehicle collision warning and traffic information dissemination have made VANET an interesting field of mobile wireless communication. This paper provides an overview on current research state, challenges, potentials of VANETs as well as the ways forward to achieving the long awaited ITS

Electromagnetic models for passive tag to tag communications

The UHF passive radio frequency identification technology generally enables an asymmetric interaction between the reader and the tag, the latter only being able to respond to the query of the reader through backscattering modulation. Very recently, some experiments put into evidence the possibility to set up a tag-to-tag communication by using a simple illuminator. The key issues and the physical limitation of such a cross-link are here investigated both theoretically and numerically by fully accounting for the mutual coupling among the tags, their radiation properties and the impedance modulation. The analysis reveals that the cross-link range may be optimized by a proper design of the tags' input impedance and that alignment of a multiplicity of tags could be able to communicate according to a simple routing strategy

Compact planar L-band antenna arrays with optimal diversity performance

At L-band (1-2GHz) due to significantly large freespace wavelengths, compact antenna arrays with small interelement separation i.e., d < λ/2, are a suitable choice for overall size reduction. However, mutual coupling becoming prominent in compact arrays results in a degradation of the diversity degreesof- freedom, which are required for beamforming capabilities in modern receivers. In this paper we discuss a potential approach to mitigate this limitation. We present empirical results for an eigenmode analysis applied to the radiation matrices of compact planar arrays, derived from the far-field integration of complex realised-gain matrices. Furthermore, optimal arrangements for compact planar arrays with respect to the highest possible value of minimum eigenmode efficiency are discussed. It could be shown that planar arrays have higher efficiencies and lower radiation correlation, hence better diversity degrees-of-freedom than linear arrays, particularly in a compact configuratio

IEEE Antennas & Propagation Magazine : Vol. 55, No. 6, December 2013

1. Passive UHF RFID antennas for sensing applications: principles, methods, and classifications. 2. A Digitally beam-steerable antenna aray system for positioning-based tracking application. 3. Multi-objective self organizing migrating algorithm applied to the design of electromagnetic components. 4. An efficient iterative MoM-PO hybird method for analysis of an onboard wire antenna aray on a large-scale platform above an infinte ground. 5. A Unified solution of laplace\u27s equation in an arbitrary region. 6. A Wideband circularly polarized stacked slotted microstrip patch antenna. 7. Analysis of shorted-plate compact and broadband microstrip antenna

Multi-Chip RFID antenna integrating shape-memory alloys for detection of thermal thresholds

Low-cost wireless measurement of objects’ tempera- ture is one of the greatest expectation of radiofrequency identi- fication technology for the so many applications in cold supply- chain control and safety assessment in general. In this context, the paper proposes a dual-chip UHF tag embedding shape memory al- loys (SMA) able to transform the variation of the tagged item’s temperature into a permanent change of antenna radiation fea- tures. This event-driven antenna is hence able to selectively activate the embedded microchips according to the temperature above or below a given threshold. A general design methodology for the re- sulting two-ports tag antenna is here introduced and then applied to prototypes able to work at low (around 0°C ) and high (80°C ) temperatures