Cemento y prefabricación

Not availableEl hormigón en prefabricación se caracteriza por un cierto número de particularidades que resultan de la necesidad de realizar rápidamente construcciones de calidad, con un mínimo de mano de obra. El cemento, constituyente noble del hormigón, tiene naturalmente un papel eminente en la adquisición de las calidades que le son exigidas a dicho hormigón

Reduction of the model noise in non-linear reconstruction via an efficient calculation of the incident field: application to a 434 MHz Scanner

Microwave tomography has been drastically boosted by the development of efficient reconstruction algorithms based on an iterative solution of the corresponding non-linear inverse problem. The accuracy of the electric field radiated by the antennas of a microwave scanner, inside the target area, has been shown to play a significant role on the overall image quality. Taking into account the antenna environment is of prime importance, especially when operating at low frequency. For instance, the wall of a 60 cm diameter whole-body microwave scanner cannot be neglected at 434 MHz, even when using the immersion technique consisting of putting the target in water. Indeed, at such a frequency, the attenuation introduced by water is not sufficient to avoid multiple reflections on the scanner boundary walls. Consequently, the method of calculating the incident field constitutes a key factor in iteratively solving non-linear inverse problems. The selected technique must accommodate high accuracy while maintaining acceptable calculation complexity. In this paper, three distinct techniques are analysed. They are based on the use of i) free-space and ii) non free-space Green's function, and iii) a FDTD approach. All these techniques have been firstly investigated for their 2D version, being used in 2D reconstruction algorithms. However, the scattered field data are collected in a 3D scanner. For assessing the validity of the previous 2D techniques, their results have been compared to both experimentally and 3D-FDTD results.Peer ReviewedPostprint (published version

Microwave imaging techniques for biomedical applications

Microwaves have been considered for medical applications involving the detection of organ movements and changes in tissue water content. More particularly cardiopulmonary interrogation via microwaves has resulted in various sensors monitoring ventricular volume change or movement, arterial wall motion, respiratory movements, pulmonary oedema, etc. In all these applications, microwave sensors perform local measurements and need to be displaced for obtaining an image reproducing the spatial variations of a given quantity. Recently, advances in the area of inverse scattering theory and microwave technology have made possible the development of microwave imaging and tomographic instruments. This paper provides a review of such equipment developed at Suplec and UPC Barcelona, within the frame of successive French-Spanish PICASSO cooperation programs. It reports the most significant results and gives some perspectives for future developments. Firstly, a brief historical survey is given. Then, both technological and numerical aspects are considered. The results of preliminary pre-clinical assessments and in-lab experiments allow to illustrate the capabilities of the existing equipment, as well as its difficulty in dealing with clinical situations. Finally, some remarks on the expected development of microwave imaging techniques for biomedical applications are given.Peer ReviewedPostprint (published version

Immunohistochemical detection of aetiological agents of proliferative and necrotizing pneumonia in Italian pigs

Proliferative and necrotizing pneumonia (PNP) is a form of interstitial pneumonia that occurs in weaning and post-weaning pigs. PNP is characterized by hypertrophy and hyperplasia of type II pneumocytes and coagulative necrosis and granular debris within alveolar spaces. Canadian and European studies suggest that the porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are the main causes of the disease, but Aujezsky's disease virus (ADV) and swine influenza virus (SIV) have also been considered as potential aetiological agents. An immunohistochemical study was carried out on the lungs of 28 Italian pigs with PNP in order to evaluate the role of PRRSV, PCV2 and ADV in PNP lesions. PRRSV infection was identified in the lungs of 11 pigs, PCV2 in the lungs of four pigs and coinfection with both viruses in the lungs of eight pigs. Neither virus was detected in the lungs of the remaining five pigs. ADV antigen was not detected in any sample. The principle aetiological agent of PNP in Italy therefore appears to be PRRSV. Coinfection with PRRSV and PCV2 is characterized by more severe microscopical changes in affected lungs

A UWB micro-strip antenna design and simulation

International audienc

Quantitative microwave imaging with a 2.45 GHz planar microwave camera

International audienc