E.ON (France)

Two best friends, a duck and a rabbit, play together at the park when a cool cat appears with a Gameboy, leading the curious rabbit to leave their best friend alone.

Unstable charge pumps used as rectifier circuits for triboelectric generators, like the Bennet’s doubler, have been proven to drastically improve the harvested power compared to traditional diode bridges, at the cost of longer starting time. In this work, we propose for the first time a kinetic energy harvesting system based on the Bennet’s doubler, polarizing two triboelectric transducers with antiphasic capacitance variations, instead of just one triboelectric transducer. We show that this configuration reduces the time needed to reach the circuit’s unstable regime compared to its single-transducer counterpart. Consequently, the harvested power is increased.

International audience

The present article proposed a numerical approach to accurately evaluate the size- and shape-dependent effective moduli of engineering heterogeneous materials containing arbitrarily shaped interfaces exhibiting both displacement and normal traction discontinuities. First, boundary condition on a representative volume element (RVE) and the effective moduli of composites involving interfacial discontinuities are precisely defined based on micromechanics. Then, a numerical approach framed within the extended finite element method (XFEM) together with the level set method (LSM) is elaborated to evaluate the averaged physical quantities over a RVE and the effective moduli of composites. Further, the unified scheme in Duan et al. (2007) to evaluate the effective moduli of composites is extended to the materials with physics-based general imperfect interfaces, and a benchmark problem is designated based on the approximated analytic formula of the effective moduli and utilized to test the validity and robustness of the elaborated numerical approach. All predictions show good agreement with the relevant analytic results. Finally, the numerical approach validated is applied to investigate the size- and shape-dependent effective moduli of composites and some concluding remarks are given.

This article examines the promise of market democratization conveyed by consumer rating and review websites in the restaurant industry. Based on interviews with website administrators and data from the main French platforms, we show that review websites contribute to the democratization of restaurant criticism, which first started in the 1970s, both by including a greater variety of restaurants in the reviews, and by broadening participation, opening restaurant reviewing to all. However, this twofold democratic ambition conflicts with the need to produce fair and helpful recommendations, leading review websites to seek compromises between these two dimensions.

Chapter 8 considers the capital problem of heredity. The conservation of genomes over the ages is shown to blatantly contradict the existence of frequent mutations in genomes of somatic cells. This contradiction can be solved only by hypothesizing that genomes are endowed with error-correcting codes. Moreover, the better conservation of very old part of the genome like the HOX genes suggests that the genomic error-correcting code should combine a number of nested component codes which appeared progressively during the evolution process, and can be likened to Barbieri’s organic codes. It is shown that these hypotheses meet reality and explain a number of facts left unexplained by mainstream biology: genomes are immensely redundant, discrete species exist which moreover can be ordered according to a hierarchical taxonomy, and nature proceeds with successive generations. Evolution appears as contingent and saltationist because the genetic information originates in regeneration errors. Even the trend of evolution towards increased complexity , hence towards longer genomes, is explained by the better performance of long error-correcting codes, which thus have been favoured by Darwinian selection. We introduce a very simple model of ‘genomes’ consisting of binary sequences subjected to random errors. They are either left uncoded, or encoded by means of a simple error-correcting code. They are periodically replicated, and regenerated if they have been encoded. The resulting population of ‘genomes’ is referred to as ‘toy living world’. We examine the permanence of such ‘genomes’ in the presence of random symbol errors, with and without error correction. If the genomes are not coded, a chaotic set of ‘genomes’ results where ‘species’, i.e., populations of identical ‘genomes’, are the more fleeting, the longer they are. Only the existence of error correction can account for the permanence of ‘genomes’ of lengths compatible with those of actual genomes and the existence of discrete species. The hypothesized genomic error-correcting codes remain unidentified although some guesses can be made about them, and the means of their regeneration remain unknown.

It is argued in Chap. 9 that information is specific to life. The concept of ‘semantic feedback loops’ is first introduced in order to explain the onset of living structures and their conservation. The basic fact is that certain proteins act as enzymes which catalyze the operations which are needed for their own synthesis: transcription of DNA into messenger or premessenger RNA, splicing out the introns (in the case of eukaryotic cells) and translation as operated by the ribosome, i.e., synthesizing proteins under the control of messenger RNA. This can be interpreted as a set of interwoven feedback loops which all involve the genetic ‘code’ (or mapping). This set of loops acts as a trap since, once closed, it keeps its structure. If any of its parts fails, however, the whole system ceases operating. We refer to it as ‘semantic’ because the genetic mapping consists of a set of semantic rules. Hence, the set of feedback loops implements the semantics which enables the assembly of proteins (and more generally of phenotypes) in terms of the information that DNA bears. This shows how information, as an abstract fundamental entity, controls the assembly of physical structures. ‘Abstract’ should be understood here as opposed to physical, since assuming that information is physical leads to results which contradict its very definition. The set of semantic feedback loops, although each loop is closed, does not prevent the lengthening of genomes by horizontal genetic transfer, hence is compatible with evolution. The last section of this chapter examines the achievements of Nature as an engineer and pleads for a collaboration of engineers and biologists.

Huge dynamic Stark shifts of atomic energy levels in xenon induced by high-intensity laser light have been mesured by a new method based upon multiphoton ionization by a tunable femtosecond laser source. Stark-induced multiphoton resonances appear as identifiable structures in the photoelectron energy spectra1. The change in the structures positions, when the photon energy is tuned, is directly related to the energy change of the atomic levels as a function of intensity. Shifts of the order of the electron-volt have thus been measured in xenon and found to vary linearly with intensity.