Current State of Research at Imperial College London in RF Harvesting and Inductive Power Transfer

This paper presents simulation and experimental results for ambient RF energy harvesting and Inductive Power Transfer systems. End-to-end and dc-load efficiency measurements and calculations were performed to demonstrate the capabilities of both systems, respectively. An RF spectral survey was conducted across all the 270 underground stations in London. DTV, GSM900, GSM1800 and 3G were selected as the highest contributors and single banded rectennas were fabricated for all frequencies. Ground level measurements demonstrate that more than 50 stations have suitable channel power levels per band to allow ambient RF energy harvesting. Efficiencies of up to 40% were achieved with a single banded rectenna operating at GSM 900, and efficiencies higher than 20% were achieved for TV and 3G. Furthermore a high frequency, semi-resonant Class-E driver was used to transfer 60 W of power across a 30 cm distance with a dc-load efficiency of 66%

The largest European theropod dinosaurs: remains of a gigantic megalosaurid and giant theropod tracks from the Kimmeridgian of Asturias, Spain

The Kimmeridgian Vega, Terenes and Lastres formations of Asturias have yielded a rich vertebrate fauna, represented by both abundant tracks and osteological remains. However, skeletal remains of theropod dinosaurs are rare, and the diversity of theropod tracks has only partially been documented in the literature. Here we describe the only non-dental osteological theropod remain recovered so far, an isolated anterior caudal vertebra, as well as the largest theropod tracks found. The caudal vertebra can be shown to represent a megalosaurine megalosaurid and represents the largest theropod skeletal remain described from Europe so far. The tracks are also amongst the largest theropod footprints reported from any setting and can be assigned to two different morphotypes, one being characterized by its robustness and a weak mesaxony, and the other characterized by a strong mesaxony, representing a more gracile trackmaker. We discuss the recently proposed distinction between robust and gracile large to giant theropod tracks and their possible trackmakers during the Late Jurassic-Berriasian. In the absence of complete pedal skeletons of most basal tetanurans, the identity of the maker of Jurassic giant theropod tracks is difficult to establish. However, the notable robustness of megalosaurine megalosaurids fits well with the described robust morphotypes, whereas more slender large theropod tracks might have been made by a variety of basal tetanurans, including allosaurids, metriocanthosaurids or afrovenatorine megalosaurids, or even exceptionally large ceratosaurs. Concerning osteological remains of large theropods from the Late Jurassic of Europe, megalosaurids seem to be more abundant than previously recognized and occur in basically all Jurassic deposits where theropod remains have been found, whereas allosauroids seem to be represented by allosaurids in Western Europe and metriacanthosaurids in more eastern areas. Short-term fluctuations in sea level might have allowed exchange of large theropods between the islands that constituted Europe during the Late Jurassic

Utilization of Varying Colors of Light Emitting Diodes in Vertical Farms for Solanum lycopersicum (Tomato)

In response to climate change and significant decreases of arable land in developing nations, vertical farming has emerged as a suitable alternative to the conventional method of farming with its use of modern technologies such as LED lights. Since previous literature on this subject had mainly focused on the effects of blue and red lights concerning plant growth, this research paper involved 620 nm (pink light), 550 nm (green light), and the combination of the colors in the color spectrum (white light) to expand the scope of the study. The facilities used for the experiment were a multiple-row vertical setup and a raised bed garden for the conventional setup. These setups were created using recyclable wood and furniture. Measuring tapes and finger-counting were utilized to detail the average height and number of leaves of plants within a specified group. One-way analysis of variance and repeated measures variance was used to show the variance or consistency of each group and significant differences between all groups. The results had depicted pink-colored LEDs to have yielded the best results by the end of the experiment with an average plant height of 10.39 cm and an average leaf number of 3.1. Overall, the vertical farming setups outperformed the conventional farm setup in terms of both mean plant height and number of leaves

Inductive power transfer system

An inductive power transfer system comprises a transmitter circuit comprising a transmitter coil and a receiver circuit comprising a receiver coil spaced from the transmitter coil. The transmitter circuit is in the form of a Class E amplifier with a first inductor and a transistor in series between the terminals of a power supply. A first transmitter capacitance is in parallel with the transistor between the first inductor and a power supply terminal, a primary tank circuit in parallel with the first transmitter capacitance, the primary tank circuit comprising the transmitter coil and a second transmitter capacitance arranged in parallel with the transmitter coil, and a third transmitter capacitance in series with the first inductor between the first transmitter capacitance and the primary tank circuit. The second transmitter capacitance is selected such that a resonant frequency of the primary tank circuit is not equal to the first frequency

Analysis of Scalable Rectenna Configurations for Harvesting High Frequency Ambient Radiation

Published versio

Maximising the Link Efficiency of Resonant Inductive Coupling for Wireless Power Transfer

Accepted versio

RF energy harvester

Disclosed herein is an antenna apparatus for use in harvesting ambient radio frequency, RF, energy. The apparatus comprises one or more RF antenna components arranged to receive RF energy for producing electricity. The one or more RF antenna components comprise a plurality of frequency filtering components, each frequency filtering component being arranged to filter a respective frequency band of the received RF energy. Also disclosed herein is an apparatus comprising a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy. The apparatus also comprises a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit. The rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines. The power management module is arranged at least partially within a boundary defined by the plurality of transmission lines