In this article we propose a new method for reducing Newtonian noise in laser-interferometric gravitational-wave detectors located on the Earths surface. We show that by excavating meter-scale recesses in the ground around the main test masses of a g
ravitational wave detector it is possible to reduce the coupling of Rayleigh wave driven seismic disturbances to test mass displacement. A discussion of the optimal recess shape is given and we use finite element simulations to derive the scaling of the Newtonian noise suppression with the parameters of the recess as well as the frequency of the seismic excitation. Considering an interferometer similar to an Advance LIGO configuration, our simulations indicate a frequency dependent Newtonian noise suppression factor of 2 to 4 in the relevant frequency range for a recesses of 4m depth and a width and length of 11m and 5m, respectively. Though a retrofit to existing interferometers seems not impossible, the application of our concept to future infrastructures seems to provide a better benefit/cost ratio and therefore a higher feasibility.
In this article we describe our efforts of extending demand-side control concepts to the application in portable electronic devices, such as laptop computers, mobile phones and tablet computers. As these devices feature built-in energy storage (in th
e form of batteries) and the ability to run complex control routines, they are ideal for the implementation of smart charging concepts. We developed a prototype of a smart laptop charger that controls the charging process depending on the locally measured frequency of the electricity grid. If this technique is incorporated into millions of devices in UK households, this will contribute significantly to the stability of the electricity grid, help to mitigate the power production fluctuations from renewable energy sources and avoid the high cost of building and maintaining conventional power plants as standby reserve.
