104 research outputs found

    Dense and long-term monitoring of Earth surface processes with passive RFID -- a review

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    Billions of Radio-Frequency Identification (RFID) passive tags are produced yearly to identify goods remotely. New research and business applications are continuously arising, including recently localization and sensing to monitor earth surface processes. Indeed, passive tags can cost 10 to 100 times less than wireless sensors networks and require little maintenance, facilitating years-long monitoring with ten's to thousands of tags. This study reviews the existing and potential applications of RFID in geosciences. The most mature application today is the study of coarse sediment transport in rivers or coastal environments, using tags placed into pebbles. More recently, tag localization was used to monitor landslide displacement, with a centimetric accuracy. Sensing tags were used to detect a displacement threshold on unstable rocks, to monitor the soil moisture or temperature, and to monitor the snowpack temperature and snow water equivalent. RFID sensors, available today, could monitor other parameters, such as the vibration of structures, the tilt of unstable boulders, the strain of a material, or the salinity of water. Key challenges for using RFID monitoring more broadly in geosciences include the use of ground and aerial vehicles to collect data or localize tags, the increase in reading range and duration, the ability to use tags placed under ground, snow, water or vegetation, and the optimization of economical and environmental cost. As a pattern, passive RFID could fill a gap between wireless sensor networks and manual measurements, to collect data efficiently over large areas, during several years, at high spatial density and moderate cost.Comment: Invited paper for Earth Science Reviews. 50 pages without references. 31 figures. 8 table

    A Software Defined Radio Interrogator for Passive Harmonic Transponders

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    Passive wireless sensors provide an opportunity for long term monitoring of remote environments. Since these devices are not battery powered, they can be deployed for an indefinite amount of time. Such devices are energized by an interrogation signal that enables them to transmit information via a return signal. Some systems (e.g., RFID) utilize the same frequency for interrogation and the return, which causes unwanted interference, particularly in cluttered environments. This work considers an interrogation system for a different class of passive devices, i.e., passive harmonic transponders. Specifically, results are presented for a single-board software defined radio (SDR) interrogation system which transmits an interrogation signal at 1.3 GHz and receives a return at 2.6 GHz. The system is demonstrated with a passive, chip-less device known as a frequency doubling reflectenna (FDR). The SDR platform enables a compact, low-cost, and quickly operating design. The mean absolute error of the proposed interrogator was found to be 1.15 dB when compared with laboratory-grade instrumentation. Additionally, this system is capable of interrogating up to a distance of 70 cm with an EIRP of only 0 dBm. This thesis presents an SDR system made with the open-source software package, GNURadio, capable of interrogating harmonic transponders with a single, full-duplex board. All signal processing is conducted on a laptop computer, eliminating the need for expensive laboratory instrumentation. The size of the system interrogator was also minimized, reducing the form factor of the whole interrogator to be only 25 ×\times 15 cm. Furthermore, a new harmonic transponder was designed using transmission line matching methods, eliminating the need for discrete matching components. This harmonic transponder has a conversion loss of 31.04 dB at an input power of -28.21 dBm as demonstrated with the SDR interrogator

    Air Force Institute of Technology Research Report 2014

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    This report summarizes the research activities of the Air Force Institute of Technology’s Graduate School of Engineering and Management. It describes research interests and faculty expertise; lists student theses/dissertations; identifies research sponsors and contributions; and outlines the procedures for contacting the school. Included in the report are: faculty publications, conference presentations, consultations, and funded research projects. Research was conducted in the areas of Aeronautical and Astronautical Engineering, Electrical Engineering and Electro-Optics, Computer Engineering and Computer Science, Systems Engineering and Management, Operational Sciences, Mathematics, Statistics and Engineering Physics

    Special oils for halal and safe cosmetics

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    Three types of non conventional oils were extracted, analyzed and tested for toxicity. Date palm kernel oil (DPKO), mango kernel oil (MKO) and Ramputan seed oil (RSO). Oil content for tow cultivars of dates Deglect Noor and Moshkan was 9.67% and 7.30%, respectively. The three varieties of mango were found to contain about 10% oil in average. The red yellow types of Ramputan were found to have 11 and 14% oil, respectively. The phenolic compounds in DPKO, MKO and RSO were 0.98, 0.88 and 0.78 mg/ml Gallic acid equivalent, respectively. Oils were analyzed for their fatty acid composition and they are rich in oleic acid C18:1 and showed the presence of (dodecanoic acid) lauric acid C12:0, which reported to appear some antimicrobial activities. All extracted oils, DPKO, MKO and RSO showed no toxic effect using prime shrimp bioassay. Since these oils are stable, melt at skin temperature, have good lubricity and are great source of essential fatty acids; they could be used as highly moisturizing, cleansing and nourishing oils because of high oleic acid content. They are ideal for use in such halal cosmetics such as Science, Engineering and Technology 75 skin care and massage, hair-care, soap and shampoo products
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