Single-channel laser Doppler vibrometers integrated on silicon-on-insulator (SOI)

Multi-location velocity measurements of a vibrating surface are of interest recently. By scanning the laser beam of a single-point laser Doppler vibrometer (LDV) across the surface of interest, one can realize the multi-location vibration measurement. However, the recovered velocity values of different locations are not obtained at the same time. In many applications, such as measuring the aortic pulse wave velocity, simultaneous velocity measurements for different locations are required. Multi-channel LDVs can be used in this case, in which multiple laser beams are generated and sent to the surface of interest simultaneously. However, the complexity of realizing the multiple interferometers in a bulk LDV system will increase as the number of channels increases, and thus it is very hard to realize a bulk LDV with many channels We propose to use the silicon-on-insulator (SOI) chip as a platform of the multi-channel interferometers. With the help of silicon photonics and CMOS technology, multiple interferometers can be miniaturized and fabricated on SOI chips. Laser beams are sent into or out of the chip through optimized on-chip grating couplers, with the coupling insertion loss of less than 2 dB per coupler. The total footprint of the integrated multiple interferometers can be very small (several square of millimetres) compared to a bulk LDV system. The cost of the chips will be dramatically decreased for mass production. Additionally, the stability of the integrated interferometers is much better than that of the interferometer built with discrete optical components

Continuous cellular automata on irregular tessellations : mimicking steady-state heat flow

Leaving a few exceptions aside, cellular automata (CA) and the intimately related coupled-map lattices (CML), commonly known as continuous cellular automata (CCA), as well as models that are based upon one of these paradigms, employ a regular tessellation of an Euclidean space in spite of the various drawbacks this kind of tessellation entails such as its inability to cover surfaces with an intricate geometry, or the anisotropy it causes in the simulation results. Recently, a CCA-based model describing steady-state heat flow has been proposed as an alternative to Laplace's equation that is, among other things, commonly used to describe this process, yet, also this model suffers from the aforementioned drawbacks since it is based on the classical CCA paradigm. To overcome these problems, we first conceive CCA on irregular tessellations of an Euclidean space after which we show how the presented approach allows a straightforward simulation of steady-state heat flow on surfaces with an intricate geometry, and, as such, constitutes an full-fledged alternative for the commonly used and easy-to-implement finite difference method, and the more intricate finite element method

Tracking uncertainty in a spatially explicit susceptible-infected epidemic model

In this paper we conceive an interval-valued continuous cellular automaton for describing the spatio-temporal dynamics of an epidemic, in which the magnitude of the initial outbreak and/or the epidemic properties are only imprecisely known. In contrast to well-established approaches that rely on probability distributions for keeping track of the uncertainty in spatio-temporal models, we resort to an interval representation of uncertainty. Such an approach lowers the amount of computing power that is needed to run model simulations, and reduces the need for data that are indispensable for constructing the probability distributions upon which other paradigms are based

The Tension Between Privacy and Security

A Review of President’s Review Group on Intelligence and Communications Technologies, Liberty and Security in a Changing World, 2013 and United Nations Office of the High Commissioner, Report of the Special Rapporteur on the Right to Privacy, Joseph A. Cannataci, 2016

A threshold for majority in the context of aggregating partial order relations

We consider a voting problem where voters have expressed their preferences on a single set of objects. These preferences take the shape of strict partial order relations. In order to allow extraction of a unique strict partial order relation corresponding to a social set of preferences, we determine the minimum number of votes a pairwise preference should receive in order to qualify as a social pairwise preference. Transitive closure of the social pairwise preferences will result in the social set of preferences. At the same time, the social set of preferences needs to be cycle-free, and the minimum number of votes should be determined with this constraint in mind. We provide an example application