Full-wave electromagnetic modelling of fabrics and composites

In this paper different types of fabrics and composites with conducting yarns are considered. The topology of the fabrics or composites is described using the type of format used in software tools originally developed to model their mechanical properties. The topology is simplified using a special conversion technique in order to allow fast electromagnetic analysis. Different possible approximations of conducting yarns used in the electromagnetic analysis are discussed. The analysis itself consists of the solution of the integral equations for the electric currents flowing on the conducting yarns, using the method of moments (MoM). For plane wave excitation the shielding effectiveness is calculated. The agreement between theory and experiments confirms the validity of the approach.     

Using wireless technology to develop a virtual reality command and control centre

This paper investigates the applicability of wireless communication systems for use in command and control environments. Human positional data is transmitted over a wireless network. This data is then used to update a highly accurately modelled real-time 3D environment of the surroundings, with avatars positioned at the transmitted points. The data is displayed on a stereoscopic 3D screen enabling novel automatic tracking of human movement and allowing for more rapid and informed tactical decision making. The system has applicability in a variety of C4I environments, including the military and emergency services.     

Direct model optimisation for data inversion. Application to ultrasonic characterisation of heterogeneous welds

Numerous multipass welds in austenitic stainless steel are made on the primary circuits of nuclear power stations. The heterogeneous anisotropic nature of these welds causes disturbance to ultrasonic propagation. Simulation is a useful tool when attempting to understand physical phenomena. With this objective, a finite element code called ATHENA was developed. Sufficiently realistic modelling of the material is proposed by the Modelling anIsotropy from Notebook of Arc welding (MINA) model, which determines the orientation of the weld grains. Optimisation by inversion of the MINA model is proposed in this study. The results validate the strategy and open perspectives regarding use on real data.     

Response of scid mice to establishment of Leishmania major infection

The initiation of Leishmania major infection in susceptible BALB/c mice is regulated by interferon-gamma (IFN-gamma). To examine further the mechanisms of IFN-gamma-dependent regulation of the establishment of L. major, we studied the characteristics of the infection in severe combined immunodeficient (scid) mice. In the first 2 weeks of infection, we observed a delay in the development of the lesions in the footpads and lower numbers of parasites in scid compared with BALB/c mice. By week 5 after infection, the size of the leishmanial lesion was similar in both strains of mice, but the number of parasites in scid mice was 100-fold higher than in BALB/c. Treatment with anti-IFN-gamma during the establishment of L. major did not alter the course of infection in scid mice, while it exacerbated lesion development in BALB/c mice. Macrophages from scid mice were unable to kill L. major when stimulated with IFN-gamma in vitro, and produced lower levels of nitric oxide compared with macrophages from susceptible BALB/c or the resistant C57Bl/6 mice. We examined whether delayed lesion development in scid mice was due to their inability to mount appropriate inflammatory responses. While significantly fewer nucleated cells were present in the footpads of scid mice compared with BALB/c, 2 and 3 weeks after infection, no difference in inflammatory response between scid and BALB/c mice was observed in response to L. major antigen in the footpads. In contrast, there was a dramatic increase in the number of cells in the popliteal lymph nodes of BALB/c mice. Decreased inflammatory responses of scid mice in the footpad (at the site of infection) may contribute to slower development of leishmanial lesions during the first 2 weeks of infection.     

Intoxication from Veratrum album

Two new cases of Veratrum poisoning are described. Clinical symptoms occurred quickly, within 30 min. Vomiting, a fall in blood pressure and bradycardia were observed. The outcome was favourable in both cases, producing a cure without sequellae. Examination of the literature showed that such cases are nearly always accidental, resulting from the difficulty in distinguishing Veratrum album and Gentiana.     

Prognostic significance of silent myocardial ischaemia during maximal exercise testing after a first acute myocardial infarction

Clinical, exercise, and angiographic variables, and long-term follow-up were compared in patients, who, during maximal Bruce exercise testing after a first acute myocardial infarction (AMI), had positive responses to exercise testing (n = 116, 38% of 303) with (n = 23, group I) or without (n = 93, group II) angina. Group I patients more often (52 vs 19%, P < 0.001) had a history of pre-infarction angina. Group II had a greater proportion (75 vs 52%, P < 0.05) of inferior wall AMI, whereas group I had a greater proportion (30 vs 19%, P < 0.01) of non-Q wave AMI. Total exercise duration was significantly (P < 0.01) longer in group II (7.6 +/- 3.2 vs 5.5 +/- 3.1 min). Maximal exercise heart rate (144 +/- 22 vs 133 +/- 21, beats.min-1 P < 0.05) was also higher in group II. A greater proportion of group II patients (37 vs 9%, P < 0.05) had single-vessel disease, whereas multivessel disease was more common (91 vs 63%, P < 0.03) in group I. Left ventricular function was similar in both groups. During follow-up (48 +/- 22 months) the incidence of cardiac death (group I, 3.3%, group II, 4.8%), of recurrent infarction (group I, 4.8%, group II 3.3%), and of revascularization procedures (group I, 28.5%, group II, 19.8%) were similar in both groups. Although asymptomatic exercise-induced ischaemia was associated with better exercise performance and less extensive coronary disease than symptomatic ischaemia, it had the same long-term prognostic implications.     

Submarine hull integrity under blast loading

The paper deals with numerical methodologies to model and study the structural resistance of submarine hull against explosions, where fluid and solid phenomena interact. Explosion Crack Starter Tests (ECST), which are a standard procedure to study submarine materials and weldments with respect to blast loading, are modelled using an explicit FE code that solves Fluid/Structure (F/S) interactions within the same computation. The proposed numerical methods aim at computing the structural response of a target subjected to sequential explosions. Numerical results are compared to the corresponding explosion tests (ECST) performed by DGA (French Ministry of Defence).