Control and filter design of three-phase inverters for high power quality grid connection

Published versio

High-quality power generation through distributed control of a power park microgrid

Published versio

Demand management for home energy networks using cost-optimal appliance scheduling

This paper uses problem decomposition to show that optimal dynamic home energy prices can be used to reduce the cost of supplying energy, while at the same time reducing the cost of energy for the home users. The paper makes no specific recommendations on the nature of energy pricing, but shows that energy prices can normally be found that not only result in optimal energy consumption schedules for the energy provider's problem and are economically viable for the energy provider, but also reduce total users energy costs. Following this, the paper presents a heuristic real-time algorithm for demand management using home appliance scheduling. The presented algorithm ensures users' privacy by requiring users to only communicate their aggregate energy consumption schedules to the energy provider at each iteration of the algorithm. The performance of the algorithm is evaluated using a comprehensive probabilistic user demand model which is based on real user data from energy provider E.ON. The simulation results show potential reduction of up to 17% of the mean peak-to-average power estimate, reducing the user daily energy cost for up to 14%

Interaction design for rural agricultural sensor networks

We describe the ongoing design of a sensor network for small family farms in rural Kenya. The sensor network is just one part of an ‘ecology of resources’ in which handheld devices are used to bridge the sensor network and a computer-based access point. We describe the two villages where the system is deployed and the user requirements collected. We then describe the architecture of the sensor network and detail how it fits in with the larger integrated system. We then detail our approach to interface and interaction design, and conclude by describing the next steps in the project

A Bitter Pill: The Primordial Lithium Problem Worsens

The lithium problem arises from the significant discrepancy between the primordial 7Li abundance as predicted by BBN theory and the WMAP baryon density, and the pre-Galactic lithium abundance inferred from observations of metal-poor (Population II) stars. This problem has loomed for the past decade, with a persistent discrepancy of a factor of 2--3 in 7Li/H. Recent developments have sharpened all aspects of the Li problem. Namely: (1) BBN theory predictions have sharpened due to new nuclear data, particularly the uncertainty on 3He(alpha,gamma)7Be, has reduced to 7.4%, and with a central value shift of ~ +0.04 keV barn. (2) The WMAP 5-year data now yields a cosmic baryon density with an uncertainty reduced to 2.7%. (3) Observations of metal-poor stars have tested for systematic effects, and have reaped new lithium isotopic data. With these, we now find that the BBN+WMAP predicts 7Li/H = (5.24+0.71-0.67) 10^{-10}. The Li problem remains and indeed is exacerbated; the discrepancy is now a factor 2.4--4.3 or 4.2sigma (from globular cluster stars) to 5.3sigma (from halo field stars). Possible resolutions to the lithium problem are briefly reviewed, and key nuclear, particle, and astronomical measurements highlighted.Comment: 21 pages, 4 figures. Comments welcom