A user centric approach to the development and testing of a home energy management system

The development and small scale field trial in Flanders of a home energy management system is presented. During the development, a user-centric approach was used to create interaction between developers and possible end-users in a living lab setting. This allowed actively addressing people’s needs and wants in the development process and testing the system in their homes. The preliminary results of the field trial indicate a high usage during the starting week, which gradually slows down over the weeks that follow. Usage of the different elements in the system varies over the weeks but a consistent “top 3” of elements remains. Dynamic pricing is used by a small but consistent part of the participants. They actively adapt their appliance usage to these prices

The euro, five years later : what has happened to prices ?

While both the creation of the Economic and Monetary Union in 1999 and the introduction of the euro banknotes and coins in January 2002 actually went remarkably smooth, the introduction of the euro gave rise to a very lively debate regarding its impact on inflation. Indeed, the vast majority of consumers, both in the euro area as a whole and in Belgium, were, and still are, under the impression that the new currency has led to pronounced price increases. This article analyses both the movement of actual prices over the five years following the changeover to the euro and the trend in inflation perceptions as indicated by the European Commission’s consumer survey. It also considers a number of factors which may have contributed to the breaking of the link between actual and perceived inflation. There is clear evidence that the euro cash changeover led to a severing of the link between actual and perceived inflation. However, the direct impact on inflation was small in 2002. But, as it was concentrated in certain less competitive sectors where isolated goods and services are purchased, it was fairly visible. Since then, inflation has remained relatively low, but there has been greater dispersion in the movement of relative prices. At the microeconomic level, the process of price adjustment, which seems relatively slow, gave rise to a new attractive price structure and an increase in the number of prices used in the economy. Such structural changes probably imply that consumers experience difficulties in getting used to the euro. At the same time, these observations also illustrate indirectly that the process of adjusting prices to the euro is correctly reflected in the data used to measure inflation, so that the HICP is an accurate measure of inflation, even if consumers may see things differently. While the changeover’s role in the development of a persistent perception gap cannot be denied, it is very difficult to identify possible explanatory factors more precisely. The statement that consumers tend to form their perceptions on the basis of the movement in prices of frequently purchased items is not sufficient to explain a persistent perception gap. The socioeconomic characteristics of consumers did not play a dominant role either, while the impact of more psychological factors is difficult to assess. The specific characteristics of the HICP inflation measurement do not appear to have played a significant role in the emergence of the perception gap in the euro area. A similar gap arises when the national CPIs are used as benchmarks instead of the HICP ; the non-inclusion of the costs of owner occupied housing was not a key factor either. The fact that the accuracy and credibility of the HICP per se are not at stake is reassuring from the point of view of monetary policy.euro cash changeover, inflation, perceived inflation

Introducing smart grids in residential contexts : consumers' perception of smart household appliances

A more energy efficient supply and demand in household settings is high on the agenda. Smart grids, smart meters, demand side management and smart appliances play a crucial role in this context. Many stakeholders are involved, but the exact role of the customer is often neglected. More specifically, his opinion, attitude, drivers or barriers towards new ways of energy consumption and energy management. This paper employs a user-centric perspective. It aims at mapping consumers perception of the possibilities of demand side management through smart household appliances. A quantitative survey was conducted among 500 households spread over Flanders, Belgium. In this paper, the results of this survey with regard to the respondents perception of smart appliances are presented. The Technology Acceptance Model was used as the theoretical framework to measure these perceptions

Assessing the Gap between Observed and Perceived Inflation in the Euro Area : Is the Credibility of the HICP at Stake ?

We find strong econometric support for a break in the relationship between perceived and HICP inflation in the euro area, triggered by the introduction of euro notes and coins in January 2002. The break is fairly homogeneous across individuals with different socio-economic characteristics. We found no support for the thesis according to which perceptions are systematically formed by frequently purchased products. A similar break is found when national CPIs instead of HICPs are used as benchmarks. The role of the non-inclusion of owner-occupied housing in the HICP was negligible. Therefore the credibility of the HICP per se is not at stake.inflation, perceived inflation, panel unit roots tests

To Kill but Not Be Killed: A Delicate Balance

Before launching a missile, it is necessary to design an efficient safety net for self-protection. In this issue of Cell, Ellermeier et al. (2006) describe the mechanism underlying a biological safety net for the soil bacterium Bacillus subtilis. This bacterium protects itself from a toxic protein it secretes by upregulating an immunity protein, which it does by sequestering a transcriptional repressor at the plasma membrane

Towards external injection in laser wakefield acceleration

In laser wakefield acceleration (LWA) a plasma wave is driven by a high intensity ultra short laser pulse and the longitudinal electric fields in the plasma wave are used to accelerate electron bunches. Electrons with an appropriate kinetic energy, injected on the right phase of the plasma wave, get trapped by the plasma wave and are accelerated. This thesis investigates experimentally the feasibility of LWA with injected electron bunches produced by a radio frequency photogun. A laser system was developed which is able to focus 3 TW pulses on a spot with a 1/e2 radius of 40 µm and a shot-to-shot position stability of 4 µm. Accelerating distances exceeding the Rayleigh length of the laser are achieved by preforming the plasma density profile to obtain a collimated propagation of the laser pulse through the plasma (guided laser pulse). The laser pulses are guided over centimeter scale distances through a capillary discharge plasma with an on-axis electron density of ~1×1024 m-3. The guiding properties of the plasma channel were investigated. It is found that a second discharge current pulse through the plasma, ~1 µs after the primary discharge, improves the guiding properties considerably. The transmittance is higher (>90%), the guided laser spot is more cylindrically symmetric at the exit of the plasma channel and the time-window for guiding becomes approximately 10 times longer (~600 ns). An RF-photogun had been purpose-built as an injector of electrons into the plasma channel. Different properties of the RF-photogun and the electron bunches produced were measured to determine the optimal settings for LWA. For an electron bunch with 10 pC charge and 3.7 MeV kinetic energy, the energy spread is 0.5% and the transverse emittance is 1.9 µm. After focusing the electron bunch at the entrance of the plasma channel by a pulsed solenoid lens, the focal spot has an RMS radius (standard deviation) of 40 µm with a shot-to-shot position stability of 5 µm. The RMS length of this electron bunch, derived from simulations, is 400 fs at focus. The arrival time jitter between laser pulse and electron bunch at the entrance of the plasma channel was inferred from earlier work to be around 150 fs in the present setup. This implies consistent temporal overlap between the laser wakefield and the injected electron bunch. The shot-to-shot stability and focal spot of the laser pulse and electron bunch at focus shows that there is always good overlap in transverse direction between the injected electron bunch, the laser pulse and the plasma channel. Due to technical difficulties, the energy of the electrons from the RF-photogun was limited to 3.7 MeV. With this energy, the injector can serve for one particular version of laser wakefield acceleration, i.e. injection ahead of the laser pulse. Using the actually measured electron bunch parameters and simulating the injection of a 3.7 MeV electron bunch of 10 pC in front of a 25 TW laser pulse with a waist of 30 µm in a plasma with a density of 0.7×1024 m-3, the maximum accelerated charge was found to be 1.2 pC with a kinetic energy of ~900 MeV and an energy spread of ~5%. These results show that laser wakefield acceleration of electrons injected by an RF photogun is feasible