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This paper presents a novel leakage model for transformers that includes losses. This new model is physically based (topological) and it is possible to connect it to a topological core model without using any fictitious windings. The methods to calculate its parameters from standard test data and from design data are detailed within the paper. The results show that the new coupled leakage model with losses is able to match exactly the test report, when using standard test data. Preliminary investigations show that the results are very close to measurements, when using design data.

BACKGROUND: The absence of fever in bacteremia in patients who are older is known to delay diagnosis. Our objective was to determine whether atypical presentation was associated to mortality as a result of bacteremia in this patient cohort as well as possible factors associated with this atypical presentation. METHODS: We conducted an observational prospective study in 2 French university hospitals in 2016-2017 including patients ages >/=75 years with bacteremia. Atypical presentation was defined as the absence of a temperature >/=38.3 degrees C or

This two-part paper is intended to clarify definitions in dual transformer modeling that are vague, provide accurate modeling guidelines, clarify misconceptions about numerical instability, provide a unified dual model for a specific type of transformer, and introduce new paths of research to the power systems/electrical machinery community for low-frequency transients. Part I discussed the topology of duality-based models and some important issues, such as the most common approaches to derive dual models and their variety, the equivalence of negative inductance and mutual couplings to represent the leakage inductance of three-winding transformers, and the numerical oscillations caused by the use of nontopological models. This part of the paper discusses and compares white-, gray-, and black-box models. The paper also reviews hysteresis models (static and dynamic) and highlights the differences between the air-core inductance and saturation inductance. The available dual models for the representation of the transformer tank are then presented. A unified and accurate model of a three-phase core-type transformer adequate for all low-frequency transients is presented. Finally, concrete guidelines are presented for the appropriate selection of the model topology and parameters for different low-frequency transient studies.

In this paper, a critical review of existing methods to couple magnetic circuits to electric circuits is provided and explained using a two-port element called mutator. In order to couple magnetic circuits in electromagnetic transients-type programs, a new implementation of mutators is described, which uses the commonly available coupled series R-L branches. The practical case of a single-phase two-winding transformer is studied, and the results show that the new method is equivalent to the dual (inductive) model. However, it is concluded that the new method is more interesting than duality to couple large 3-D topological models (transformers, lines, motors, etc.), because it avoids difficulties of duality associated with nonplanar magnetic circuits.

This paper presents experimental validation of the coupled leakage inductance transformer model. It is shown that the coupled approach yields the same results as the indefinite admittance matrix method of BCTRAN. A topologically correct three-phase shell-type transformer model is proposed. The connection points between the leakage and magnetizing inductances are properly identified, which makes the new model superior to BCTRAN and the hybrid models, by providing physical consistency. Additionally, experimental verification of a method to calculate the short-circuit inductances is presented. New explanations on the division of leakage flux and on the mathematical equivalence between the T- and ⇑-equivalent models are also given.

In this paper, a new method for the calculation of leakage inductances between short-circuited windings is proposed. The main objective is to find an analytical alternative to the finite element method (FEM) for the computation of short-circuit inductances in electromagnetic transients type (EMT-type) programs. Typical EMT-type tools do not provide complex FEM based computation engines for this sole purpose. The new approach is derived from the method of images and uses analytical formulations for magnetic vector potential and energy developed in this work. It is shown that the difference between the inductance calculated with the FEM in 2-D and that computed with the method of images decreases as the number of layers of images increases. Also, it is demonstrated that the classical approach, based on an axial flux distribution, can lead to considerable error if the windings have unequal heights and if they are located far from the core yokes.

The objective of this two-part paper is to provide clarity to physical concepts used in the field of transformer modeling, to dispel common misconceptions regarding numerical instabilities, and to present unified modeling techniques for low-frequency transients. This paper focuses on proper modeling of nonlinearities (magnetizing branches) since these components are critical to determine the low-frequency behavior. A good low-frequency model should properly represent: normal operation, inrush currents, open and short circuit, out-of-phase synchronization transient of step-up transformers, geomagnetic-induced currents, ferroresonance, and harmonics. This paper discusses the derivation of electrical dual models from the equivalent (magnetic) reluctance networks and the direct application of the principle of duality. It is shown that different dual models need to be derived for different transformer geometries and the advantages and disadvantages of each method are discussed. This paper also compares double-sided versus single-sided dual models, and shows that the double-sided model is a more general approach. The mathematical equivalency of several leakage models (negative inductance, mutual coupling, and BCTRAN) is demonstrated for three-winding transformers. It is also shown that contrary to common belief, a negative inductance is not the source of numerical oscillations, but they occur due to the use of noncorrect topological models for representing the core.

The reactions occurring between gases/aerosols and silicate ash particles in volcanic eruption plumes remain poorly understood, despite the fact that they are at the origin of a range of volcanic, environmental, atmospheric and health effects. In this study, we apply X-ray photoelectron spectroscopy (XPS), a surface-sensitive technique, to determine the chemical composition of the nearsurface region (2-10 nm) of nine ash samples collected from eight volcanoes. In addition, atomic force microscopy (AFM) is used to image the nanometer-scale surface structure of individual ash particles isolated from three samples. We demonstrate that rapid acid dissolution of ash occurs within eruption plumes. This process is favoured by the presence of fluoride and is believed to supply the cations involved in the deposition of sulphate and halide salts onto ash. AFM imaging also has permitted the detection of extremely thin (< 10 nm) coatings on the surface of ash. This material is probably composed of soluble sulphate and halide salts mixed with sparingly soluble fluoride compounds. The surface approach developed here offers promising aspects for better appraising the role of gas/aerosol-ash interaction in dictating the ability of ash to act as sinks for various volcanic and atmospheric chemical species as well as sources for others. (c) 2007 Elsevier B.V. All rights reserved.

Members of the Mycoplasma mycoides cluster’ represent important livestock pathogens worldwide. Mycoplasma mycoides subsp. mycoides is the etiologic agent of contagious bovine pleuropneumonia (CBPP), which is still endemic in many parts of Africa. We report the genome sequences and annotation of two frequently used challenge strains of Mycoplasma mycoides subsp. mycoides, Afade and B237. The information provided will enable downstream ‘omics’ applications such as proteomics, transcriptomics and reverse vaccinology approaches. Despite the absence of Mycoplasma pneumoniae like cyto-adhesion encoding genes, the two strains showed the presence of protrusions. This phenotype is likely encoded by another set of genes.

L'utilisation d'alliages legers dans le domaine des transports (routiers, aeronautiques et nautiques) ne cesse de croitre dans un interet de gain en masse et par consequent d'economie d'energie. Au cours de leur vie en service, les pieces des vehicules de transport sont en particulier soumises a des chargements cycliques de faible amplitude (i.e. fatigue) et a des chargements severes (i.e. choc). Dans un souci d'ameliorer et renforcer la securite, il est necessaire d'etudier et de comprendre la reponse mecanique des materiaux metalliques sous des conditions severes, telles que les chargements dynamiques, ainsi que l'influence que peut avoir un prechargement de fatigue sur cette reponse. L'objet de ce papier est la presentation de resultats obtenus sur des alliages d'aluminium dans le cadre d'etudes de tenues residuelles en traction par choc suite a un preendommagement de fatigue. Apres une introduction definissant le contexte general de l'etude de cumul de sollicitations demarree au LAMEFIP et donnant quelques resultats issus de la litterature, nous presentons les dispositifs de chargement experimentaux et la geometrie specifique des echantillons. Nous illustrons enfin les campagnes menees sur deux alliages d'aluminium industriels utilise en aeronautique (AA2017A-T3) et dans l'industrie automobile (AA5454-O), avant de discuter des resultats obtenus.

This work attempts to link tribological and adhesion phenomena in fretting conditions. Fretting experiments were carried out in three environmental conditions (air atmosphere, demineralized water and kerosene) and with various couples of industrial materials. Contacting materials and liquids were chosen mainly for their surface properties, in order to have a wide range of surface free energies. The fretting device included a pin-on-plane configuration. The pin (or slider) was fixed and the plane was the moving substrate. The total distance (d T ) covered by the moving substrate was chosen as the tribological parameter representative of the history of an experiment. The distance d T was then compared to surface parameters such as Dupre's work of adhesion between the two substrates in contact (w 12 ) and with three bodies (w 132 ), the index 3 being the liquid medium. In these conditions, d T = f(w 12 ) and d T = f(w 132 ) variations were found to be linear, thus showing a clear link between friction and adhesion.

The mechanisms of the sliding friction of rubber-like materials are studied on a microscale level, by scrutinising phenomena occurring inside contact area between a moving hard transparent spherical asperity and the smooth, flat surface of a soft elastomer sample. We study experimentally the behaviour of the detachment fold or Schallamach waves (Shallamach, A. Wear 197117, 301–312) when the rubber temperature varies between 20 and 42°C. Our analysis is based on the space-time evolution diagrams, composed by superimposition of contact area cross-sections, recorded one after the other. We aimed to demonstrate how the application of this method does permit us to obtain the results in real time.

The structure and mass transfers at Piton de la Fournaise volcano are investigated using new on land and offshore measurements. The structures are defined using 2 and 3D modelling. Short-wavelength positive anomalies to the W and NW of the central area are interpreted as shallow piles of thick, dense lava flows which have filled volcano-tectonic depressions, several hundreds of meters deep. This finding provides a new insight into the evolution of the volcano. Conversely, the currently active central zone is associated with a negative short-wavelength anomaly, explained by the presence of thin, highly vesiculated and fractured lava flows building the Central Cone. Low density formations underlying the Rivieres des Remparts and Langevin areas are tentatively interpreted as breccias related to erosion and/or to southward directed mass-wasting. Topographic offshore highs in the continuation of the SE and NE rift zones of Piton de la Fournaise are characterized by negative gravity anomalies and reversed magnetic anomalies. Their interpretation as hyaloclastites and pillow lavas provides a coherent explanation for both types of signals if we admit that they were primarily constructed during the Alizes stage. Two main deeper, dense structures are also found: the Grand Brule complex, and a complex beneath the Plaine des Sables and the Enclos Fouque. Both are identified as hypovolcanic intrusive complexes. The Grand Brule complex (10 × 18 km in plan view) shows a marked NS-elongated geometry, unlike the other comparable complexes on the island. The Plaine des Sables-Enclos Fouque complex, a more or less circular structure 5 km in diameter, is attributed to the Ancient Shield stage. It is centered on the Enclos fault, suggesting that the paleo-center of the Ancient Shield was located about 1.5 km eastward of the previously proposed location. An apparent contradiction was noted between the seismic and gravity images of the internal structure. In particular, a high velocity cylinder beneath the summit was not detected in the gravity models. This contradiction was resolved by considering the relative sensitivity of each method. Finally, the gravity dataset has allowed us to explore the gravity changes that accompanied the major eruptive and volcano-tectonic crisis of April 2007 (350 m collapse of the summit and emission of ∼ 120 × 106 m3 of lava). The change in the mass distribution of the edifice was large enough to be detected in the survey data collected in the central area before and after the crisis. However, the accuracy was too low for the precise assessment of the mass transfers.

International audience; Electron beam lithography on Langmuir−Blodgett films of alkanethiol-capped gold nanoparticles is shown to be a viable strategy to define nanometer scale structures of such particles. Sub-50 nm wide “nanowires”, the thickness of which is controlled at the single particle level, are created with e-beam doses in the mC/cm 2 range. It is shown that the patterns are formed by radiation-induced cross-linking of the alkyl chains and that they can be contacted and studied electrically.