Polynomial-Chaos-based Kriging

Computer simulation has become the standard tool in many engineering fields for designing and optimizing systems, as well as for assessing their reliability. To cope with demanding analysis such as optimization and reliability, surrogate models (a.k.a meta-models) have been increasingly investigated in the last decade. Polynomial Chaos Expansions (PCE) and Kriging are two popular non-intrusive meta-modelling techniques. PCE surrogates the computational model with a series of orthonormal polynomials in the input variables where polynomials are chosen in coherency with the probability distributions of those input variables. On the other hand, Kriging assumes that the computer model behaves as a realization of a Gaussian random process whose parameters are estimated from the available computer runs, i.e. input vectors and response values. These two techniques have been developed more or less in parallel so far with little interaction between the researchers in the two fields. In this paper, PC-Kriging is derived as a new non-intrusive meta-modeling approach combining PCE and Kriging. A sparse set of orthonormal polynomials (PCE) approximates the global behavior of the computational model whereas Kriging manages the local variability of the model output. An adaptive algorithm similar to the least angle regression algorithm determines the optimal sparse set of polynomials. PC-Kriging is validated on various benchmark analytical functions which are easy to sample for reference results. From the numerical investigations it is concluded that PC-Kriging performs better than or at least as good as the two distinct meta-modeling techniques. A larger gain in accuracy is obtained when the experimental design has a limited size, which is an asset when dealing with demanding computational models

Measurement-based modeling of RF-EMF exposure in urban environments using artificial intelligence techniques

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Imagining the Body in Pacific Francophone Literature

This article deals with the central position of the body in Polynesian and Kanak imaginary, ancestral myths, and language. In the collective imagination, the body is akin to a particle of the cosmos. The author probes into major primordial images in order to understand the peculiar role of the body in the Oceanic "anthropological structures of the imaginary" (Gilbert Durand’s term) and asks whether the vision proposed by archaic myths finds its way into modern autochthonous Polynesian and Kanak indigenous literature, especially in the writings of Déwé Gorodé, Chantal Spitz, Flora Devatine, and Moetai Brotherson. Indeed, in keeping with the theories of Michel Foucault, the Oceanic body as it appears in modern poetic or novelistic narrations bears witness in its maimed flesh to a collective history and bears the scars of colonialism. Through its transhistorical dimension as well, this brand of francophone literature constitutes an original way to introduce some sort of counter-discourse into narrative strategies shaped by Western colonial history. In reclaiming the body, these writers are also reviving an ancestral voice

A novel method to assess human population exposure induced by a wireless cellular network

<p>This paper presents a new metric to evaluate electromagnetic exposure induced by wireless cellular networks. This metric takes into account the exposure induced by base station antennas as well as exposure induced by wireless devices to evaluate average global exposure of the population in a specific geographical area. The paper first explains the concept and gives the formulation of the Exposure Index (EI). Then, the EI computation is illustrated through simple phone call scenarios (indoor office, in train) and a complete macro urban data long-term evolution scenario showing how, based on simulations, radio-planning predictions, realistic population statistics, user traffic data, and specific absorption rate calculations can be combined to assess the index.</p

Advances in imaging of new targets for pharmacological intervention in stroke: real-time tracking of T-cells in the ischaemic brain

Background and purpose: T‐cells may play a role in the evolution of ischaemic damage and repair, but the ability to image these cells in the living brain after a stroke has been limited. We aim to extend the technique of real‐time in situ brain imaging of T‐cells, previously shown in models of immunological diseases, to models of experimental stroke. Experimental approach: Male C57BL6 mice (6–8 weeks) (n= 3) received a total of 2–5 × 106 carboxyfluorescein diacetate succinimidyl ester (CFSE)‐labelled lymphocytes from donor C57BL6 mice via i.v. injection by adoptive transfer. Twenty‐four hours later, recipient mice underwent permanent left distal middle cerebral artery occlusion (MCAO) by electrocoagulation or by sham surgery under isoflurane anaesthesia. Female hCD2‐green fluorescent protein (GFP) transgenic mice that exhibit GFP‐labelled T‐cells underwent MCAO. At 24 or 48 h post‐MCAO, a sagittal brain slice (1500 µm thick) containing cortical branches of the occluded middle cerebral artery (MCA) was dissected and used for multiphoton laser scanning microscopy (MPLSM). Key results: Our results provide direct observations for the first time of dynamic T‐cell behaviour in living brain tissue in real time and herein proved the feasibility of MPLSM for ex vivo live imaging of immune response after experimental stroke. Conclusions and Implications: It is hoped that these advances in the imaging of immune cells will provide information that can be harnessed to a therapeutic advantage

RF-EMF exposure induced by mobile phones operating in LTE small cells in two different urban cities

With the huge growth in data traffic, the densification of the macro cell (MC) layer with low-powered small cell (SC) base stations (resulting in a heterogeneous network) will improve network performances in terms of radio coverage and capacity. However, this may influence the human exposure to radiofrequency electromagnetic fields (RF-EMFs). Through measurement campaigns in two different urban cities (in France and the Netherlands), the authors characterized the RF-EMF exposure induced by LTE (Long-Term Evolution) MC and SC networks, while considering radio emissions from both base stations (downlink or DL) and user equipment (uplink or UL). For an internet data usage and with respect to an MC connection, results showed that an SC connection may increase the DL exposure while decreasing the UL exposure (with a factor of 5 to 17), mainly due to the lower mobile phone emitted power and depending on whether the throughput is limited or not. Furthermore, the city with a dense network is characterized by low UL exposure and high DL exposure