Quelques réflexions sur les particularités de l’architecture de Léningrad dans les années 1920­1930

Soviet architectural avant­garde from the 1920s­30s arouses , since a few years, a new interest in Russia , which however does not reflect the state of conservation of these building . In this context , this article proposes to shed light on the avant­garde in Leningrad (St Petersburg ), insisting on its stylistic and conceptual peculiarities, and telling the story of its main architects. Leningrad avant­garde has indeed a very specific importance in Soviet architecture. This reflection allows to better grasp the obvious reasons of its necessary preservation , while the monuments are still threatened and in danger. Doing so, it invites the independent experts, activists from Leningrad and cultural actors to take part in the preservation of these architectural masterpieces.L’architecture soviétique d’avant­garde (années 1920­1930 ) suscite, depuis peu, un vif intérêt en Russie, qui ne coïncide cependant pas avec l’état de conservation de ces bâtiments. Dans ce contexte, cet article propose de mettre la lumière sur l’avant­garde de Léningrad (Saint­Pétersbourg ) en insistant sur ses particularités tant stylistiques que conceptuelles et en revenant sur les principaux architectes de l’époque. En effet, l’avant­garde de Léningrad possède une place particulière dans l’architecture soviétique. Cette réflexion contemporaine permet de mieux saisir les raisons de la nécessaire protection de ces bâtiments, aujourd'hui menacés et en danger, et invite les experts indépendants , les militants léningradois et acteurs culturels à s’investir dans la préservation de ces bijoux architecturaux.Kirikov Boris m. Quelques réflexions sur les particularités de l’architecture de Léningrad dans les années 1920­1930. In: Revue Russe n°53, 2019. Le patrimoine russe et soviétique : construction, déconstruction, reconstruction. pp. 15-23

Pulse micro-surfacing as nonconventional method within the comprehensive technology of the gas-turbine engine recovery

The results of the experimental studies on the choice of optimal surfacing material for a pulse micro-surfacing of the details made of monocrystal nickel superalloys are set out. The microstructure, the microhardness, the adhesion strength and the heat-resistant stability of the built-up zones have been analyzed. The results of the research have been introduced within the elaboration of technological process of recovering working capacity and prolongation of a resource of the first step working blades of gas turbines SGT-800 Siemens, having completed their operating life (~23 000 equivalent hours)

THE PECULIAR DOMAIN STRUCTURE AND ITS UNUSUAL BEHAVIOUR IN THE β-PHASE OF THE FERROELECTRIC NaH3(SeO3)2

On étudie les particularités du comportement de la structure au domaine dans la phase β de NaH3(SeO3)2. Nous montrons que les parois du domaine qui ne sont pas à 180°, et qui sont parallèles au champ appliqué se chargent. Dans ce cas les processus de polarisation du cristal sont le siège d'un état qui n'a jamais été observé à notre connaissance : le remplacement irréversible de pressions chargées pour des parois non chargées et stables perpendiculaires à E. Les particularités des courbes P(E) correspondent au comportement spécifique de la structure au domaine.The peculiarities of the behaviour of the domain structure in β-phase NaH3(SeO3)2 are studied. It is shown that non 180° domain walls being parallel to the applied field become charged. In this case the further process of polarization of the crystal contains the stage, which has not been observed so far : irreversible replacing of charged walls by stable uncharged walls perpendicular to E. The peculiarities of curves P(E) correspond to the specific behaviour of the domain structure

Morphological characteristics of the intermetallic phase of heat resisting nickel alloys

The paper discusses the main stages of the automatic quantitative analysis of parameters of the'-dispersed phase in high-temperature polycrystalline nickel alloys and indicates their main difference from the standard methods of analyzing disconnected phases. We present 4 classes of characteristics of dispersed phase particles. These characteristics include the volume fraction, the dimensional parameters of particles and the spatial distribution parameters. For example, we calculated the parameters of the '-phase of a blade made of a heat resisting nickel alloy In792. The volume fraction and the equivalent diameter of the '-phase disperse particles increase in operation while their concentration decreases. These parameters of the '-phase change with changes in the mechanical properties of the alloy. The shape of the particles and the scatter of '-phase concentration change little in the process of operation