WITH the ever-widening scope of modern mathematical analysis and its many ramifications, it is quite impossible to include, in a single volume of reasonable size, an adequate and exhaustive discussion of the calculus in its more advanced stages. It therefore becomes necessary, in planning a thoroughly sound course in the subject, to consider several important aspects of the vast field confronting a modern writer. The limitation of space renders the selection of subject-matter fundamentally dependent upon the aim of the course, which may or may not be related to the content of specific examination syllabuses. Logical development, too, may lead to the inclusion of many topics which, at present, may only be of academic interest, while others, of greater practical value, may have to be omitted. The experience and training of the writer may also have, more or less, a bearing on both these considerations.Advanced CalculusBy Dr. C. A. Stewart. Pp. xviii + 523. (London: Methuen and Co., Ltd., 1940.) 25s.

Advanced Calculus I

Antenna Theory And Design

A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

Post-transition elements, together with zinc-group metals and their alloys belong to an emerging class of materials with fascinating characteristics originating from their simultaneous metallic and liquid natures. These metals and alloys are characterised by having low melting points (i.e. between room temperature and 300 °C), making their liquid state accessible to practical applications in various fields of physical chemistry and synthesis. These materials can offer extraordinary capabilities in the synthesis of new materials, catalysis and can also enable novel applications including microfluidics, flexible electronics and drug delivery. However, surprisingly liquid metals have been somewhat neglected by the wider research community. In this review, we provide a comprehensive overview of the fundamentals underlying liquid metal research, including liquid metal synthesis, surface functionalisation and liquid metal enabled chemistry. Furthermore, we discuss phenomena that warrant further investigations in relevant fields and outline how liquid metals can contribute to exciting future applications.

Liquid metals: fundamentals and applications in chemistry

The current evolution of the traditional medical model toward the participatory medicine can be boosted by the Internet of Things (IoT) paradigm involving sensors (environmental, wearable, and implanted) spread inside domestic environments with the purpose to monitor the user’s health and activate remote assistance. RF identification (RFID) technology is now mature to provide part of the IoT physical layer for the personal healthcare in smart environments through low-cost, energy-autonomous, and disposable sensors. It is here presented a survey on the state-of-the-art of RFID for application to bodycentric systems and for gathering information (temperature, humidity, and other gases) about the user’s living environment. Many available options are described up to the application level with some examples of RFID systems able to collect and process multichannel data about the human behavior in compliance with the power exposure and sanitary regulations. Open challenges and possible new research trends are finally discussed.

RFID Technology for IoT-Based Personal Healthcare in Smart Spaces

We present the comparison of wearable passive UHF RFID tags based on dipole and patch antennas made of textile materials. The tags' wireless performance was evaluated when attached to the upper back of a test subject. Despite the fundamentally different structures and electromagnetic operation mechanisms of the antennas, both tags attained read ranges of several meters. In the optimized configuration, the patch tag achieved slightly higher performance, but was found to be more sensitive toward variable antenna-body separation.

Comparison of wearable passive UHF RFID tags based on electro-textile dipole and patch antennas in body-worn configurations

We outline the possibilities of 3D direct write dispensing and brush-painting in the manufacturing of copper UHF RFID tags on textile and cardboard materials and present considerations regarding the process parameters to achieve high-performance tags when the copper antenna is deposited directly on these rough and porous materials. Our measurement results confirm that the additively-manufactured copper RFID tags on environmental-friendly substrates achieve high performance with the attainable theoretical read ranges of 3.5-to-8.5 meters in air.

Additive manufacturing of antennas from copper oxide nanoparticle ink: Toward low-cost RFID tags on paper- and textile-based platforms

Wearable antennas are paramount components of a new era of wireless body-centric sensing systems by extending the functionality of daily garments. Garment-integrated sensor networks within biomedicine and personal healthcare demand information about sensed or measured biological parameters to be reliably and quickly delivered over a wireless communication link for analysis purposes. The totally maintenance-free, conformal, low-cost and low-power wearable antennas have an enormous potential for fulfilling these requirements. They may be considered as a benchmark in personal healthcare domain, ultimately making concepts like telemedicine to become reality.

https://www.ursi.org/Proceedings/ProcGA14/papers/ursi_paper1645.pdf

On-body antennas: Towards wearable intelligence

Silver ink conductors and passive ultra-high frequency (UHF) radio frequency identification (RFID) tags were printed by the screen printing method on stretchable PVC substrate. Two inks with different particle content were used. We investigated the electrical performance of the conductors in unloaded conditions and during straining with resistance measurement. The printed RFID tags were characterized in similar circumstances through wireless tag measurements. The goal of the study was to evaluate the usability of printed conductors and RFID tags as strain sensors and to find out, if it is possible to modify their strain sensitivity by adjusting the ink particle content. The results showed that the particle content could be used to modify the strain sensors based on printed conductors and RFID tags. Both structures offer various possibilities for applications, such as monitoring of human bodily functions and movements.

Modification of printed wearable strain sensors by PTF ink particle content adjustment

Design of a circularly polarized tag antenna for UHF RFID applications is discussed and a planar tag antenna, based on series connected loop topology is designed. Simulation based design process for axial ratio optimization is discussed and the simulation and measurement results for the proposed tag antenna are presented. ↕ 1 line space

Toni Bjorninen

Papers

Comparison of wearable passive UHF RFID tags based on electro-textile dipole and patch antennas in body-worn configurations

Additive manufacturing of antennas from copper oxide nanoparticle ink: Toward low-cost RFID tags on paper- and textile-based platforms

On-body antennas: Towards wearable intelligence

Modification of printed wearable strain sensors by PTF ink particle content adjustment

Circularly Polarized Tag Antenna for UHF RFID