Physics

Enhanced widely linear filtering to make quasi-rectilinear signals almost equivalent to rectilinear ones for saic/maic

P.Chevalier , R.Chauvat , J.Delmas


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Widely linear receivers have the capability to perform single antenna interference cancellation of one rectilinear or quasi-rectilinear co-channel interference , a function which is operational in global system for mobile communications handsets in particular. Moreover, SAIC technology for QR signals is still required for voice services over adaptive multi-user channels on one slot standard, a recent evolution of GSM/EDGE standard, to mitigate legacy GSM CCI in particular. It is also required for filter bank multi-carrier offset quadrature amplitude modulation networks, which are candidate for 5G mobile networks, to mitigate inter-carrier interference at reception for frequency selective propagation channels in particular. In this context, the purpose of this paper is twofold. The first one is to get more insights into the existing SAIC technology, and its extension to multiple antenna called MAIC, by showing analytically that, contrary to what is accepted as true in the literature, SAIC/MAIC implemented from standard WL filtering may be less efficient for QR signals than for R ones. From this result, the second purpose of the paper is to propose and to analyze, for QR signals and frequency selective fading channels, a SAIC/MAIC enhancement based on a three-input WL frequency shift receiver, making QR signals always almost equivalent to R ones for WL filtering in the presence of CCI. The results of the paper, completely new, may contribute to develop elsewhere new powerful WL receivers for QR signals and for both VAMOS and FBMC-OQAM networks in particular.

Dna Methylation in Human Epigenomes Depends on Local Topology of CpG Sites

S.K. , D.I. , H.J. , L.C.


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In vertebrates, methylation of cytosine at CpG sequences is implicated in stable and heritable patterns of gene expression. The classical model for inheritance, in which individual CpG sites are independent, provides no explanation for the observed non-random patterns of methylation. We first investigate the exact topology of CpG clustering in the human genome associated to CpG islands. Then, by pooling genomic CpG clusters on the basis of short distances between CpGs within and long distances outside clusters, we show a strong dependence of methylation on the number and density of CpG organization. CpG clusters with fewer, or less densely spaced, CpGs are predominantly hyper-methylated, while larger clusters are predominantly hypo-methylated. Intermediate clusters, however, are either hyper- or hypo-methylated but are rarely found in intermediate methylation states. We develop a model for spatially-dependent collaboration between CpGs, where methylated CpGs recruit methylation enzymes that can act on CpGs over an extended local region, while unmethylated CpGs recruit demethylation enzymes that act more strongly on nearby CpGs. This model can reproduce the effects of CpG clustering on methylation and produces stable and heritable alternative methylation states of CpG clusters, thus providing a coherent model for methylation inheritance and methylation patterning.Cecilia Lövkvist, Ian B. Dodd, Kim Sneppen and Jan O. Haerte

Scaling and dimensional analysis of acoustic streaming jets.

D.Henry , V.Botton , J.Garandet , B.Moudjed , H.Ben-Hadid


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The present paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of governing equations under the form of a non-linear hydrodynamics problem coupled with an acoustic propagation problem is revisited. To do so, a time scale discrimination approach is preferred to the usually invoked amplitude perturbations expansion. This is indeed more consistent with experimental observations of acoustic streaming flows featuring hydrodynamic non-linearities and turbulence. Experimental results are also presented together with a review of former experimental investigations concerning the power-to-velocity relationship for plane ultrasonic transducers in water. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications but a drawback for ultrasonic velocimetry.

High-accuracy measurements on biperiodical circuits

A.D'Elia , M.Rosaria , V.Giorgio


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Coupled resonators in an assembled structure lose their individuality and in co-operation contribute to the generation of structure modes. The resonant frequencies of these modes are the only measurable quantities. In order to predict structural behaviour in a variety of cases, the problem that arises is the extraction of all the parameters characterizing the structure from the measurements mentioned here. If all the modes are confined in a bandwidth that is small with respect to the central frequency, the total coupled resonator system is well represented by a circuit of unknown lumped constants. The structure modes are the solutions of the equation obtained by equating to zero the determinant relevant to the lumped circuit representation. The equation is a polynomial of the squared frequency variable, the degree of which is equal to the number M of circuits. The analysis method described in this paper consists in varying, by an unknown amount, the frequency of a single resonator in the chain. This variation will produce a change in the frequencies of all structure modes. It is possible to find certain invariants linearly dependent on all the unchanged parameters of the circuit. These invariants have an algebraic representation that allows the extraction of the structure parameter values with extremely high accuracy. The proposed method is quite general and, in the present work, we give an example applying the method to the characterization of a side-coupled linac

Towards the improvement of un n.5 test method for the characterization of substances which in contact with water emit flammable gases

G.Marlair , J.Chaineaux , A.Janes , D.Carson


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This paper deals with a sensitivity analysis of main parameters affecting the measurement of the gas flowrate emitted during testing substances for their potential to emit flammables gases in dangerous quantities where in contact with water, according to the UN N. 5 test procedure. UN N. 5 is described in the Manual of Tests and Criteria of United Nations , serving both applications of international transport regulations as well as classifications of dangerous substances according to Globally the Harmonized System and the derived regulation applying in the EU known as 'CLP' Regulation No 1271/2008). The main reason that justifies the present research is that the measurement of emitted gases is highly critical in the final classification resulting from the interpretation of the test results. Moreover, that idea has been raised to adapt the UN N. 5 test protocol for classifying, in the future, substances that by contact with water would emit dangerous quantities of toxic gases. Experiments have been carried out to cover the analysis of the influence of ambient temperature, overall volume of glassware, nature of aqueous media, mass sample and sample-to-liquid mass ratio, since such parameters are not fixed within any defined range in the UN N. 5 test procedure. The influence of the flow rate measuring device was also considered. Results confirm that the above mentioned parameters may play a significant role to such an extent as to finally alter the final classification resulting from the testing. Guiding principles have also been derived from our measurements and observations towards an improved and more robust UN test protocol in the future.
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