This article deals with the structural behavior of a multi-bar system which maintains pole pieces in a concentric magnetic gear. Simplified analytic magnetic and mechanical models of the system are ...proposed in order to be integrated in a multi-criteria global optimization for the sizing of a magnetic gear in wind power applications. For this purpose, the reduction of the computation time is taken into account. The geometry of the support bar subsystem is defined and a Q bar structure is proposed. The magnetic study is based on Maxwell’s equations and subdomain method in order to determine variable radial and tangential magnetic loads. The mechanical study is based on a multibody model with different bars stiffnesses which are determined from a one-dimensional model. Variable radial and tangential magneto-mechanical pole pieces loads (magnetic load and weight) are also considered. An example of a magnetic gear with 172 pole pieces (i.e. 6-MW wind turbine) is proposed to analyze the mechanical behavior and also the computation time.
Maintenance of ancient road and railway metallic bridges has become a major concern for governmental agencies in the past few decades. Indeed, since the construction of these structures, between the ...end of the 19th century and the beginning of the 20th century, traffic conditions have evolved, both in weight and frequency. In the purpose to assess the remaining life of old metallic bridges, some critical structural details have been identified and associated to S-N curves in order to be used in damage estimation (using Palmgren-Miner's rule for cumulative damage, for example). These constructional details are described by design rules of several European and North American standards, such as the Eurocode 3, BS 5400 and AASHTO standards. The particularity of ancient bridges is that hot riveted assemblies, commonly used for their construction, are not represented in most construction standards. Further experiences on the matter by numerous research teams have suggested detail category C71 from the Eurocode 3 as appropriate. In this paper, experimental data from double shear assemblies manufactures from three different metallic ancient bridges is used to identify, through a statistical analysis, the S-N curves that best fit this constructional detail. Portuguese and French puddled iron bridges were considered.
We report the case of a 56-year-old HIV-seropositive man who presented a facial Demodex infection developed 2 months after initiation of highly active antiretroviral therapy. The Demodex infection ...was confirmed by scrapings and histopathologic examination and by the dramatic response to antiparasitic treatment with oral ivermectin associated with 5% permethrin cream.
Chronic meningococcemia is an unusual clinical presentation within the spectrum of infections due to Neisseria meningitidis.
We report a 32-year-old man who presented with a 15-day history of fever ...and maculopapular skin rash, in the absence of meningeal irritation or severe sepsis manifestation. Blood culture identified N. meningitidis. Clinical course was uneventful after antibiotic treatment was initiated.
Early diagnosis of chronic meningococcemia is crucial for optimal management of the patient and his/her contacts. Such a diagnosis should be suspected in the presence of the characteristic clinical triad (recurrent fever, skin rash and arthralgia), and this clinical presentation should be distinguished from systemic vasculitis as inadequate prescription of corticosteroids may be deleterious.
Parmi les manifestations cliniques des infections à
Neisseria
meningitidis, la méningococcémie chronique est singulière quant à sa sémiologie et son profil évolutif.
Nous rapportons l’observation ...d’un homme de 32 ans hospitalisé pour exploration d’une fièvre évoluant depuis 15 jours associée à une éruption cutanée maculopapuleuse diffuse et fugace, sans aucun signe de syndrome méningé ou de sepsis sévère. Une hémoculture revenait positive à
N.
meningitidis (sérotype B). L’évolution était favorable sous antibiothérapie.
La reconnaissance précoce de cette entité à partir de ses caractéristiques cliniques est essentielle pour une prise en charge efficace du patient et des sujets contacts. La méningococcémie chronique doit être évoquée devant la triade fièvre, éruption cutanée et arthralgies, et ne doit pas être confondue avec une vascularite systémique car la prescription inadéquate d’une corticothérapie peut engendrer des complications sévères.
Chronic meningococcemia is an unusual clinical presentation within the spectrum of infections due to
Neisseria meningitidis.
We report a 32-year-old man who presented with a 15-day history of fever and maculopapular skin rash, in the absence of meningeal irritation or severe sepsis manifestation. Blood culture identified
N.
meningitidis. Clinical course was uneventful after antibiotic treatment was initiated.
Early diagnosis of chronic meningococcemia is crucial for optimal management of the patient and his/her contacts. Such a diagnosis should be suspected in the presence of the characteristic clinical triad (recurrent fever, skin rash and arthralgia), and this clinical presentation should be distinguished from systemic vasculitis as inadequate prescription of corticosteroids may be deleterious.
Hot riveting was largely used as method of assembly in France during the appearing and expansion of the railway network (1840- 1940). Present in wrought iron and steel constructions, riveted ...connections are commonly found in the French railway heritage.
Conceived as a permanent assembly, these connections work by the shearing of the rivets and the friction between the plates, such friction is caused by the clamping force due to the cooling of the rivet after forging. The mechanical behavior of the assembly will depend on the many parameters involved in the process. However, three main failure modes have been identified: tension on the plates, shearing of the rivet and bearing in the plates (pressure of rivet on the rivet hole).
To understand the influence of friction in the global behavior of the assembly, a comparison between two types of S235 steel specimens is proposed. The first was a set of several hot riveted specimens and in the second one, the rivet was replaced by a martensitic stainless steel axis with a high yield stress that kept the pieces of the connection in place (no clamping force was thus present this time). The behavior of both types of specimens was then studied in tension using 3D Digital Image Correlation to analyze local and global displacements.
The comparison between the relative displacements of the connected plates of the two types of specimens allows identifying the influence of friction in the global behavior. To complete this kinematics investigation, failure scenarios are described through longitudinal cross sections analysis.
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