Wireless power and data transfer via a common inductive link using frequency division multiplexing

For wireless power transfer (WPT) systems, communication between the primary side and the pickup side is a challenge because of the large air gap and magnetic interferences. A novel method, which integrates bidirectional data communication into a high-power WPT system, is proposed in this paper. The power and data transfer share the same inductive link between coreless coils. Power/data frequency division multiplexing technique is applied, and the power and data are transmitted by employing different frequency carriers and controlled independently. The circuit model of the multiband system is provided to analyze the transmission gain of the communication channel, as well as the power delivery performance. The crosstalk interference between two carriers is discussed. In addition, the signal-to-noise ratios of the channels are also estimated, which gives a guideline for the design of mod/demod circuits. Finally, a 500-W WPT prototype has been built to demonstrate the effectiveness of the proposed WPT system.

Using alcohol unit-marked glasses enhances capacity to monitor intake:evidence from a mixed-method intervention trial

AIMS: In the UK, people tend to have poor knowledge of government guidelines for alcohol use, and lack the motivation and skills required to use them to monitor their drinking. The study aim was to determine whether using glasses marked with such guidelines would improve knowledge and attitudes, increase frequency of counting units and lower alcohol intake. METHODS: A total of 450 adults in the UK participated in an intervention vs control study with 1-month follow-up. The intervention group was encouraged to use glasses supplied by the researchers that indicated the unit content of drinks of different strengths and volumes, and stated the intake guidelines. Data were collected online. A further more in-depth interview with 13 intervention group participants enquired into their experiences of using the glasses. RESULTS: Analyses adjusted for baseline variables showed that the intervention improved the following: knowledge of unit-based guidelines, ability to estimate the unit content of drinks, attitudes toward the guidelines and frequency of counting unit intake. However, there was no significant difference in alcohol consumption between the groups at follow-up. Interviews suggested that the glasses encouraged people to think about their drinking and to discuss alcohol with other people. The design of the glasses was not appealing to all, and their initial impact did not always persist. CONCLUSION: Use of unit-marked glasses led to changes in people's reported use of unit-based guidelines to monitor their drinking but, in the short term, no change in consumption. Qualitative data suggested that the glasses could have an impact at the individual level (on knowledge and attitudes) and at a broader level (by prompting discussion of alcohol use).