Knitted electromagnetic textile surfaces

We report a commercially attractive approach to manufacturing conducting textiles which is based on computerised flat-bed knitting technology using conducting yarns. We examine how flat-bed knitting can be used to manufacture large area samples of functional electromagnetic structures such as frequency selective surfaces (FSS). In addition we show how the knitting process can be adapted to allow the integration of conducting vias into a 3-D knitted spacer structure to form an electromagnetic high impedance surface (HIS)

The Interplanetary Network Supplement to the BeppoSAX Gamma-Ray Burst Catalogs

Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 787 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments aboard the BeppoSAX spacecraft. During this period, the network consisted of up to six spacecraft, and using triangulation, the localizations of 475 bursts were obtained. We present the localization data for these events.Comment: 89 pages, 3 figures. Submitted to the Astrophysical Journal Supplement Serie

Experimental knitted, textile frequency selective surfaces

A new approach to the manufacture of conducting textiles for operation at microwave frequencies is reported. The technique investigated utilises a commercial flat-bed knitting process which is configured to use conducting yarns to produce large area, patterned, conducting textiles in an efficient manner which is amenable to mass production. The computerised flat-bed knitting system is used to manufacture example frequency selective surfaces (FSSs) using silver coated nylon yarn combined with a polyester base yarn. Reflectivity measurements are presented to confirm the basic operation of both a lowpass and a highpass knitted, textile FSS

TeV Burst of Gamma-Ray Bursts and Ultra High Energy Cosmic Rays

Some recent experiments detecting very high energy (VHE) gamma-rays above 10-20 TeV independently reported VHE bursts for some of bright gamma-ray bursts (GRBs). If these signals are truly from GRBs, these GRBs must emit a much larger amount of energy as VHE gamma-rays than in the ordinary photon energy range of GRBs (keV-MeV). We show that such extreme phenomena can be reasonably explained by synchrotron radiation of protons accelerated to \sim 10^{20-21} eV, which has been predicted by Totani (1998a). Protons seem to carry about (m_p/m_e) times larger energy than electrons, and hence the total energy liberated by one GRB becomes as large as \sim 10^{56} (\Delta \Omega / 4 \pi) ergs. Therefore a strong beaming of GRB emission is highly likely. Extension of the VHE spectrum beyond 20 TeV gives a nearly model-independent lower limit of the Lorentz factor of GRBs, as \gamma \gtilde 500. Furthermore, our model gives the correct energy range and time variability of ordinary keV-MeV gamma-rays of GRBs by synchrotron radiation of electrons. Therefore the VHE bursts of GRBs strongly support the hypothesis that ultra high energy cosmic rays observed on the Earth are produced by GRBs.Comment: Final version to appear in ApJ Lett. Emphasizing that the extremely large energy required in this model is not theoretically impossible if GRB emission is strongly beamed. References update

Knitted, textile, high impedance surface with integrated conducting vias

An experimental, microwave high impedance surface (HIS) manufactured from a combination of both conducting and insulating yarns using commercial, computerised flat-bed knitting machines is presented. The HIS consists of a knitted, conducting ground plane, a polyester spacer layer and a knitted, conducting patterned top surface. The structure also contains vias that link the conducting elements of the top layer to the ground plane. The entire structure (including the vias) is knitted in one continuous process that is both low cost and highly efficient in terms of manufacturing time. Measurements of the surface wave transmission properties of the knitted, textile HIS are made and data are presented that show that the HIS prevents surface wave transmission over a band of frequencies between 4 and 5GHz

Development of a test method for investigating moisture transfer rate of textiles

Moisture management textiles have proved to be one of the fastest growing sector in textiles. New research and development of these textiles have pushed the boundaries of textile testing equipment as new test methods are required. This paper will focus on the development of test method with potential application in testing and analyzing of textile fabrics which can be used in moisture management industry. A new system has been developed which allows fabrics moisture transmission to be tested whilst situated between two variable conditions mini chambers. The system allows moisture level to be monitored by precision weight scale and all the real-time data can be controlled and analyzed by computer. The system was tested by using a knitted spacer fabric and proved to be useful and reliable kit for analysis of moisture transmission at various testing conditions

Capacitive fiber-meshed transducers for touch and proximity-sensing applications

Capacitive sensing is been used in E-Textiles for touch sensing and proximity sensing applications. The common approach is been to construct electrode on top of a non conducting fabric structure. Woven & knitted fabric structures are been used for the construction. Metallic wire and conductive material coated fibres are primarily been used. Due to the performance degradation and poor comfort of these constructions we had constructed electrodes with inherently conductive polymers and multifilament metallic fibres by integrating into fibre meshed structures such that the electrodes are a part of the base structure. We had used capacitive and resistive techniques for the measurements. Out of many mechanical methods of fibre integrating processors we had used flat bed knitting technology. In this paper we had discussed the construction, sensing and applications of capacitive fibre-meshed transducers and their applications

Experimental knitted, textile frequency selective surfaces

A new approach to the manufacture of conducting textiles for operation at microwave frequencies is reported. The technique investigated utilises a commercial flat-bed knitting process which is configured to use conducting yarns to produce large area, patterned, conducting textiles in an efficient manner which is amenable to mass production. The computerised flat-bed knitting system is used to manufacture example frequency selective surfaces (FSSs) using silver coated nylon yarn combined with a polyester base yarn. Reflectivity measurements are presented to confirm the basic operation of both a lowpass and a highpass knitted, textile FSS

Knitted waveguide antenna

This paper presents the design of a knitted slotted waveguide antenna and its improvement. The antenna is developed originally from a textile elliptical waveguide and it has a resonant frequency at 9.15GHz with 80MHz bandwidth. Then, slight structural adjustments are taken to improve the antenna’s performance. Moreover, the measured results show that the optimized slotted waveguide antenna working at 9.18GHz with 170 MHz bandwidth has a more directional radiation pattern with a higher gain. The antenna was designed and simulated in CST Microwave Studio 2012

Understanding the design rules for a nonintrusive, textile, heart rate monitoring system

Background and Objectives: Nonintrusive heart rate (HR) monitoring can be a useful tool for health monitoring. By creating capacitively coupled textile electrodes, a comfortable monitoring system can be integrated into seating or bedding that can monitor HR through clothing. This work empirically studied two factors for a system of this type: the electrode size and the material worn by the subject. Materials and Methods: HR measurements were taken using six different sizes of the rectangular textile electrode with four subjects and the signal-to-noise ratio (SNR) of the signals were analyzed. A further set of experiments were conducted with a single subject and a fixed electrode size where different materials were worn. Results: Electrode size was seen to have a statistically insignificant effect on the collected signal quality. The SNR was also largely unaffected by the worn material type. Conclusion: This study provided empirical data relating to two important factors for nonintrusive, textile, and HR monitoring systems. This data will be helpful for designing a seat-based HR monitoring system or to understand the operational limitations of a system of this type