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Experimental Studies on Shock-Shock Interactions in Hypersonic Shock TunnelsKhatta, Abhishek January 2016 (has links) (PDF)
Shock-shock interactions are among the most basic gas-dynamic problem, and are almost unavoidable in any high speed light, where shock waves generating from different sources crosses each other paths. These interactions when present very close to the solid surface lead to very high pressure and thermal loads on the surface. The related practical problem is that experienced at the cowl lip of a scramjet engine, where the interfering shock waves leads to high heat transfer rates which may also lead to the damage of the material. The classification by Edney (1968) on the shock-shock interaction patterns based on the visualization has since then served the basis for such studies. Though the problem of high heating on the surface in the vicinity of the shock-shock interactions has been studied at length at supersonic Mach numbers, the study on the topic at the hypersonic Mach numbers is little sparse. Even in the studies at hypersonic Mach numbers, the high speeds are not simulated, which is the measure of the kinetic energy of the ow. Very few experimental studies have addressed this problem by simulating the energy content of the ow. Also, some of the numerical studies on the shock-shock interactions suggest the presence of unsteadiness in the shock-shock interaction patterns as observed by Edney (1968), though this observation is not made very clearly in the experimental studies undertaken so far.
In the present study, experiments are carried out in a conventional shock tunnel at Mach number of 5.62 (total enthalpy of 1.07 MJ/kg; freestream velocity of 1361 m/s), with the objective of mapping the surface pressure distribution and surface convective heat transfer rate distribution on the hemispherical body in the presence of the shock-shock interactions. A shock generator which is basically a wedge of angle = 25 , is placed at some dis-dance in front of the hemispherical body such that the planar oblique shock wave from the shock generator hits the bow shock wave in front of the hemi-spherical body. The relative distance between the wedge tip and the nose of the hemispherical body is allowed to change in di erent experiments to capture the whole realm of shock-shock interaction by making the planar oblique shock wave interact with the bow shock wave at different locations along its trajectory.
The study results in a bulk of data for the surface pressure and heat transfer rates which were obtained by placing 5 kulites pressure transducers, 1 PCB pressure transducer and 21 platinum thin lm gauges along the surface of the hemispherical body in a plane normal to the freestream velocity direction. Along with the measurement of the surface pressure and the surface heat
transfer rates, the schlieren visualization is carried out to capture the shock waves, expansion fans, slip lines, present in a certain shock-shock interaction pattern and the measured values were correlated with the captured schlieren images to evaluate the ow build up and steady and useful test time thereby helping in understanding the ow physics in the presence of the shock-shock interactions.
From the present study it has been observed that in the presence of Edney Type-I and Edney Type-II interaction, the heat transfer rates on the hemi-spherical body are symmetrical about the centerline of the body, with the peak heating at the centerline which drops towards the shoulder. For Edney Type-III, Edney Type-IV, Edney Type-V and Edney Type-VI interaction pattern, the distribution in not symmetrical and shifts in peak heat transfer rates being on the side of the hemispherical from which planar oblique shock wave is incident. Also, it is observed that for the interactions which appear within the sonic circle, Edney Type-III and Edney Type-IV, the heat transfer rates observe an unsteadiness, such that the gauges located close to the interaction region experiencing varying heat transfer rates during the useful test time of the shock tunnel. Few experiments were conducted at Mach 8.36 (total enthalpy of 1.29 MJ/kg; freestream velocity of 1555.25 m/s) and Mach 10.14 (total enthalpy of 2.67 MJ/kg; freestream velocity of 2258.51 m/s) for the con gurations representing Edney Type-III interaction pattern to further evaluate the unsteady nature observed at Mach 5.62 ows. The unsteadiness was evident in both the cases.
It is realized that the short test times in the shock tunnels pose a constraint in the study of unsteady flow fields, and the use of tailored mode operation of shock tunnel can alleviate this constraint. Also, limited number of experiments in the present study, which are carried out in a Free Piston Shock Tunnel, helps to understand the need to conduct such study in high enthalpy test conditions.
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Antény pro pásmo milimetrových vln / Antennas for milimeter-wave bandsPítra, Kamil January 2010 (has links)
This thesis describes design and experimental verification of three types of the wideband antenna Bow-tie antenna, Vivaldi antenna and Spiral antenna. The tracked parameters are bandwidth, input impedance, gain and directivity patterns. Next step is design of millimeter-wave horn antennas. Attention is turned to the proper construction of a wideband feeder of the horn. For the final antenna structure, a bow-tie dipole and a Vivaldi antenna were chosen. The antenna construction is aimed to provide a wide bandwidth on one hand and a high gain on the other hand.
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From Dameisho to MeishoPetko, Lukas January 2015 (has links)
Seen from abroad, Tokyo appears as a huge, vibrant metropolis where 21st-century Japan meets the traditional side of the country. Tokyo´s skyline is a diverse jumble of traditional houses and shrines, and modern architecture from skyscrapers of glass to 1970´s living capsules. Since the beginning, Tokyo has had great prerequisites for creating a city with amazing urban environment. Water was the first reason for people to settle down in Tokyo Bay. During Edo period (1603 – 1867), Tokyo was always described as a picturesque city with well-planned hydrology and a harmonic relationship with nature. With its canals full of water, it was a city comparable to Venice. The distribution and exchange relied almost entirely on water transport. With the expansion of the city, the water system had to be upgraded, which led to creating a complex network of waterways. Unlike in Western countries, where the economic, social and cultural life of the city developed around rather formal places as plazas and squares, in Japan, the lifeblood of the city developed in close connection with the water and nature. These places, also known as “meisho” (名所, lit. “famous places”) used to be linear open structures such as streets, river shores and bridges. During the transformation of Tokyo into a modern capital, the city cut many ties with the past. The unused canals suddenly became redundant and started belonging to the “wrong” side of the city. By the 1980s, many of the waterways were so polluted that the government began filling them up or covering them with elevated highways in preparation for the 1964 Tokyo Olympics. The modernization and its transformation also meant that most of the network of “meisho” and greenery have disappeared. “From dameisho to meisho” is inspired by series of woodblock prints “One Hundred Famous Views of Edo” (名所江戸百景, Meisho Edo Hyakkei) completed by the Japanese artist Hiroshige Ando (1797–1858), depicting a matrix of famous public spaces in Tokyo. My project examines the possibilities of recasting “meisho”, a spatial representation in Japanese culture, into a new, modern context via editing different layers of the city and its fabric. It explores linear, thread-like spaces such as Edo waterways, its transformations roads, as well as recently built elevated highways in order to search for contaminations and new collaborations, unexpected conditions and create new, green urban stitches. As one of the tackling tools, the project also looks at demographic trends shaping Japan and benefits from aging society and shrinking Japanese population. Last but not least I investigate ways of graphical reinterpretation of the series of woodblock prints using Tokyo and its new “meisho” spaces as a rolemodel.
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Identifying Fundamental Characteristics of Shock Nonstationarity using MMS Measurements : Identifying and Distinguishing Non-stationary Behaviour Through the Magnetic Field Gradient in Quasi-perpendicular Shocks / Indentifiera fundamentala egenskaper av icke-stationärt beteende i chocker genom MMS mätningar : Använding av magnetfältsgradienten i kvasi-vinkelräta chockar för att identifiera och urskilja icke-stationärt beteendeWik, Hannah January 2023 (has links)
Collisionless shocks are widespread phenomena in the universe, and understanding the mechanisms behind their energy dissipation, with a rare number of collisions between particles, remains a significant unresolved question. The Earth’s bow shock provides an excellent opportunity to study this phenomena in situ. For high Mach number shocks, the shock cannot be sustained without partial reflection of the incoming ions. At higher Mach numbers, the shock surface starts to exhibit non-stationary behaviours, meaning that the shock surface starts evolving. One such behaviour is known as shock reformation, where a new shock forms upstream of an existing one. This study aims to investigate shock reformation using data obtained from NASA’s MMS mission, which offers precise measurements with high spatial and temporal resolutions through its constellation of four spacecraft. Using the MMS shocks database (Lalti et al., 2022), the gradient of the magnetic field magnitude is computed to infer non-stationary behaviour and identify potential instances of shock reformation and other shock behaviours. Through the analysis of the MMS measurements, some insight into the non-stationary characteristics of shocks is obtained using the gradient of the magnetic field. However, further analysis is needed in order to refine the method of identifying non-stationary behaviour of shocks, for future applications. / Kollisionsfria chocker är ett vanligt fenomen som förekommer i universum, och att förstå hur energidissipation inträffar i chocker med ett fåtal kollisioner mellan partikar är ett olöst problem. Jordens bogchock utger en bra möjlighet att studera detta på plats med mätningar från rymdfarkoster. Detta projekt försöker studera delar av jordens bogchock och undersöka dess dynamic. För chocker med högt machtal, måste en del av jonerna från solvinden reflekteras för att chocken ska skunna upprätthållas. Vid högre machtal kan chockytan visa icke-stationära beteenden, vilket innebär att den börjar förändras. Ett exempel på sådant beteende är chockreformation, där en ny chock formas framför en befintlig chock. Denna studie har som mål att undersöka chockreformation med hjälp av data som erhållits från NASA:s MMS-uppdrag, vilket erbjuder precisa mätningar med hög rumslig och tidsmässig upplösning genom sin konstellation av fyra rymdfarkoster. Genom användning av MMS-shockdatabasen (Lalti et al., 2022) beräknades gradienten av magnetfältets magnitud för att härleda icke-stationärt beteende och identifierade potentiella fall av chockreformation och andra beteenden. Genom analys av MMS-mätningarna erhölls viss insikt i de icke-stationära egenskaperna hos chocker med hjälp av gradienten av magnetfältet, men ytterligare analys krävs för att förbättra metoden för framtida tillämpningar.
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Statistics of Electric and Magnetic Fields at the Earth’s Bow Shock / Statistik över elektriska och magnetiska fält vid jordens bogchockWong-Chan, Tsz-Kiu January 2023 (has links)
The interaction between the solar wind and Earth’s magnetic field creates the Earth’s bow shock. It is an ideal region for space probes like MMS, THEMIS or Clusters to study the collisionless shock phenomenon in space plasma. More specifically the project focuses on the topic of wave-particle interactions in the space plasma environment, which allows irreversible energy dissipation and entropy production at the event of a shock when there are a lack of collisions between particles. Research is still ongoing regarding the topic of wave-particle interactions in plasma and this project aims to contribute to our understanding of this topic. To do this, measurement data of a total of 249 shock crossing events from NASA’s Magnetospheric Multiscale (MMS) mission are used to conduct a statistical study. The study aims to analyse the correlation between the electric- and magnetic field measured close to shock-crossing events, and their respective macroscopic shock parameters in different shock regions, and at three different frequency bands for the attempt of further our understanding of the dynamics of collisionless shocks. Through scatter plots, negative correlations are found between both the electric- and magnetic field power, and the different macroscopic shock parameters at various shock regions and at various frequency ranges. This leads to the suggestion of potential dependencies between the occurrence of electrostatic and electromagnetic waves and those shock parameters. However, there is still room for improvement of the statistical method used for the correlation studies. / Interaktionen mellan solvinden och jordens magnetfält skapar jordens bogchock. Det är en idealisk region för rymdfarkoster som MMS, THEMIS eller Clusters att studera kollisionsfria chocker i rymdplasma. Mer specifikt fokuserar detta projekt på vågpartikelinteraktioner i rymdplasma, vilket möjliggör irreversibel energidissipation och entropiproduktion vid en chock när det råder brist på kollisioner mellan partiklar. Forskning pågår fortfarande inom området vågpartikelinteraktioner i plasma och detta projekt syftar till att bidra till vår förståelse av ämnet. För att göra detta används mätdata från totalt 249 chocker från NASA:s Magnetospheric Multiscale (MMS)-uppdrag för att genomföra en statistisk studie. Studien syftar till att analysera korrelationen mellan de elektriska och magnetiska fälten som mäts nära chocker och deras respektive makroskopiska chockparametrar i olika chockregioner och vid tre olika frekvensband, i ett försök att vidare förstå dynamiken hos kollisionslösa chocker. Genom spridningsdiagram hittas negativa korrelationer både mellan de elektriska och magnetiska fältstyrkan och de olika makroskopiska chockparametrarna vid olika chockregioner och frekvensband. Detta leder till förslaget om potentiella samband mellan förekomsten av elektrostatiska och elektromagnetiska vågor och dessa chockparametrarna. Det finns dock fortfarande utrymme för förbättring av den statistiska metoden som används för korrelationsstudierna.
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La Furūsiyya des Mamlûks : Une élite sociale à cheval (1250-1517)Carayon, Agnès 26 June 2012 (has links)
Les Mamlûks sont réputés pour avoir porté les arts de la furūsiyya à leur plus haute expression. Cette thèse a pour objectif de cerner à la fois les enjeux de leur dextérité, et ses caractéristiques. La première partie porte sur la littérature de la furūsiyya. Après un bilan historiographique, plusieurs ouvrages de furūsiyya sont analysés et comparés, afin de mieux appréhender les héritages et les apports proprement mamlûks. Un traité anonyme de maniement de dabbūs et de lutte à cheval, contenant également une partie sur les feux de guerre, est édité et traduit. La deuxième partie de cette thèse porte sur la suprématie militaire des Mamlûks. Leur formation très poussée y est décrite, mais la lumière a aussi été mise sur leurs chevaux : leurs races ; leur dressage ; leur nombre ; leur entretien. Un large échantillon d'armes mamlûkes est présenté. Enfin, un chapitre est consacré au problème des procédés de combat, encore très mal connus, qui tend à nuancer la vision d'archers montés que l'on a généralement des Mamlûks. Enfin, la dernière partie relève de l'histoire sociale. Elle a pour ambition de démontrer que la maîtrise de la furūsiyya était perçue par les Mamlûks comme la détention d'un art complexe, un « attribut de distinction » qui les distinguait du vulgum pecus. Ce sont alors les diverses manifestations de cette appartenance sociale qui sont analysées : les « sports » équestres, les lieux de jeu et d'entraînement militaire et les palais-écuries, enfin les institutions et les spectacles.Les annexes contiennent un tableau détaillé des manuscrits de furūsiyya et un glossaire, en plus de quelques planches. / The Mamluks are renowned for bringing the arts of furūsiyya to their highest expression. This thesis aims to identify both the issues of their dexterity, and characteristics.The first part focuses on the literature of furūsiyya. After a historiographical balance, several treatises of furūsiyya are analyzed and compared in order to better understand the legacy and contributions properly Mamluk. An anonymous treatise of handling dabbūs and fight on horseback, also containing some of the fires of war, is edited and translated.The second part of this thesis is on their military supremacy.Their extensive training is described, but the light was also put on their horses : races, training, numbers and maintenance. A wide selection of Mamluk weapons is presented. Finally, a chapter is devoted to the problem of combat methods, very little known, which tends to moderate vision of mounted archers that is generally widespread.The last part focus on social history. It aims to demonstrate that furūsiyya mastery was seen by the Mamluks as the knowledge of a complex art, an "attribute of distinction", which distinguished them from the hoi polloi. Then, the various manifestations of belonging to this social class are analyzed: "sports" riding, gambling venues and military training, and palace-stables, and finally the institutions and the shows.The appendices contain a detailed table of manuscripts of furūsiyya, a glossary and a few plates.
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Extreme-ultraviolet light generation in plasmonic nanostructures / Plasmonic enhancement of high harmonic generation revisitedSivis, Murat 13 November 2013 (has links)
No description available.
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A subjetivação da criança escolar : um estudo sobre o tempo de latênciaDrügg, Angela Maria Schneider January 2007 (has links)
A presente pesquisa consiste num estudo sobre o processo de constituição psíquica da criança em idade escolar a partir do conceito tempo de latência, buscando articulá-lo ao processo de escolarização da infância. Situa o conceito no conjunto da obra freudiana desde seus primeiros trabalhos sobre as neuroses e a sexualidade infantil, passa pelo período de formulação da teoria das pulsões, localiza-o no contexto da teoria estrutural e, igualmente, nas reflexões de Freud acerca das relações entre natureza e cultura. Em sucessão, verifica os desdobramentos que o conceito tem na obra de reconhecidos psicanalistas que se dedicaram à análise de crianças, como Melanie Klein, Anna Freud, Donald Winnicott, Charles Sarnoff e Françoise Dolto, culminando com uma leitura do tempo de latência como um tempo lógico a partir do enfoque lacaniano. Enquanto tempo lógico infere que a latência não decorre de um processo natural, desencadeado pelo organismo, e sim pela demanda do Outro. Nesse sentido procura vinculá-lo às transformações culturais da modernidade, entre estas o processo de escolarização da infância. Sustenta que a escolarização favorece a constituição do tempo de latência, na medida em a escola se organiza como o espaço social destinado à criança, distanciando-a do ambiente familiar sem, no entanto, incluí-la no mundo adulto, ao mesmo tempo em que possibilita formas de sublimação. Entendendo o tempo de latência como uma produção do laço social, cogita que novas transformações na cultura podem extingui-lo enquanto tempo constitutivo. Aponta que fraturas na sustentação do trabalho psíquico deste tempo constitutivo aparecem em algumas formações clínicas, como a inibição intelectual e a fobia escolar. / The research consists of a study on the process of psychic constitution of the child in school age from the concept of latency time, searching the education process of infancy. It points out the concept in the set of the Freudian workmanship since the first works on the neuroses and the infantile sexuality, passes for the period of formularization of the drive theory, still locates it in the context of the structural theory and in the reflections of Freud about the relations between nature and culture. To leave of this, it verifies the unfoldings that the concept has in the workmanship of recognized psychoanalysts who had dedicated themselves to analyze of children as Melanie Klein, Anna Freud, Donald Winnicott, Charles Sarnoff and Françoise Dolto, culminating with a reading of the latency time as a logical time from the lacanian approach. While logical time understands that the latency does not elapse of a natural process, unchained for the organism, and yes for the demand of the Other. In this direction it searches to tie it to the cultural transformations of modernity, between these the education process of infancy. It supports that the education favors the constitution of the latency time, in the measure where the school is organized as the social space destined to the child, distancing itself of the familiar environment without, in meanwhile include them in the adult world, at the same time where it makes possible subliming forms. Understanding the latency time as a production of the social bow, it cogitates that new transformations in the culture can extinguish it while constituent time. It points that breakings in the sustentation of the psychic work of the latency appear in some clinical formations as the intellectual inhibition and the pertaining to school phobia.
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A subjetivação da criança escolar : um estudo sobre o tempo de latênciaDrügg, Angela Maria Schneider January 2007 (has links)
A presente pesquisa consiste num estudo sobre o processo de constituição psíquica da criança em idade escolar a partir do conceito tempo de latência, buscando articulá-lo ao processo de escolarização da infância. Situa o conceito no conjunto da obra freudiana desde seus primeiros trabalhos sobre as neuroses e a sexualidade infantil, passa pelo período de formulação da teoria das pulsões, localiza-o no contexto da teoria estrutural e, igualmente, nas reflexões de Freud acerca das relações entre natureza e cultura. Em sucessão, verifica os desdobramentos que o conceito tem na obra de reconhecidos psicanalistas que se dedicaram à análise de crianças, como Melanie Klein, Anna Freud, Donald Winnicott, Charles Sarnoff e Françoise Dolto, culminando com uma leitura do tempo de latência como um tempo lógico a partir do enfoque lacaniano. Enquanto tempo lógico infere que a latência não decorre de um processo natural, desencadeado pelo organismo, e sim pela demanda do Outro. Nesse sentido procura vinculá-lo às transformações culturais da modernidade, entre estas o processo de escolarização da infância. Sustenta que a escolarização favorece a constituição do tempo de latência, na medida em a escola se organiza como o espaço social destinado à criança, distanciando-a do ambiente familiar sem, no entanto, incluí-la no mundo adulto, ao mesmo tempo em que possibilita formas de sublimação. Entendendo o tempo de latência como uma produção do laço social, cogita que novas transformações na cultura podem extingui-lo enquanto tempo constitutivo. Aponta que fraturas na sustentação do trabalho psíquico deste tempo constitutivo aparecem em algumas formações clínicas, como a inibição intelectual e a fobia escolar. / The research consists of a study on the process of psychic constitution of the child in school age from the concept of latency time, searching the education process of infancy. It points out the concept in the set of the Freudian workmanship since the first works on the neuroses and the infantile sexuality, passes for the period of formularization of the drive theory, still locates it in the context of the structural theory and in the reflections of Freud about the relations between nature and culture. To leave of this, it verifies the unfoldings that the concept has in the workmanship of recognized psychoanalysts who had dedicated themselves to analyze of children as Melanie Klein, Anna Freud, Donald Winnicott, Charles Sarnoff and Françoise Dolto, culminating with a reading of the latency time as a logical time from the lacanian approach. While logical time understands that the latency does not elapse of a natural process, unchained for the organism, and yes for the demand of the Other. In this direction it searches to tie it to the cultural transformations of modernity, between these the education process of infancy. It supports that the education favors the constitution of the latency time, in the measure where the school is organized as the social space destined to the child, distancing itself of the familiar environment without, in meanwhile include them in the adult world, at the same time where it makes possible subliming forms. Understanding the latency time as a production of the social bow, it cogitates that new transformations in the culture can extinguish it while constituent time. It points that breakings in the sustentation of the psychic work of the latency appear in some clinical formations as the intellectual inhibition and the pertaining to school phobia.
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A subjetivação da criança escolar : um estudo sobre o tempo de latênciaDrügg, Angela Maria Schneider January 2007 (has links)
A presente pesquisa consiste num estudo sobre o processo de constituição psíquica da criança em idade escolar a partir do conceito tempo de latência, buscando articulá-lo ao processo de escolarização da infância. Situa o conceito no conjunto da obra freudiana desde seus primeiros trabalhos sobre as neuroses e a sexualidade infantil, passa pelo período de formulação da teoria das pulsões, localiza-o no contexto da teoria estrutural e, igualmente, nas reflexões de Freud acerca das relações entre natureza e cultura. Em sucessão, verifica os desdobramentos que o conceito tem na obra de reconhecidos psicanalistas que se dedicaram à análise de crianças, como Melanie Klein, Anna Freud, Donald Winnicott, Charles Sarnoff e Françoise Dolto, culminando com uma leitura do tempo de latência como um tempo lógico a partir do enfoque lacaniano. Enquanto tempo lógico infere que a latência não decorre de um processo natural, desencadeado pelo organismo, e sim pela demanda do Outro. Nesse sentido procura vinculá-lo às transformações culturais da modernidade, entre estas o processo de escolarização da infância. Sustenta que a escolarização favorece a constituição do tempo de latência, na medida em a escola se organiza como o espaço social destinado à criança, distanciando-a do ambiente familiar sem, no entanto, incluí-la no mundo adulto, ao mesmo tempo em que possibilita formas de sublimação. Entendendo o tempo de latência como uma produção do laço social, cogita que novas transformações na cultura podem extingui-lo enquanto tempo constitutivo. Aponta que fraturas na sustentação do trabalho psíquico deste tempo constitutivo aparecem em algumas formações clínicas, como a inibição intelectual e a fobia escolar. / The research consists of a study on the process of psychic constitution of the child in school age from the concept of latency time, searching the education process of infancy. It points out the concept in the set of the Freudian workmanship since the first works on the neuroses and the infantile sexuality, passes for the period of formularization of the drive theory, still locates it in the context of the structural theory and in the reflections of Freud about the relations between nature and culture. To leave of this, it verifies the unfoldings that the concept has in the workmanship of recognized psychoanalysts who had dedicated themselves to analyze of children as Melanie Klein, Anna Freud, Donald Winnicott, Charles Sarnoff and Françoise Dolto, culminating with a reading of the latency time as a logical time from the lacanian approach. While logical time understands that the latency does not elapse of a natural process, unchained for the organism, and yes for the demand of the Other. In this direction it searches to tie it to the cultural transformations of modernity, between these the education process of infancy. It supports that the education favors the constitution of the latency time, in the measure where the school is organized as the social space destined to the child, distancing itself of the familiar environment without, in meanwhile include them in the adult world, at the same time where it makes possible subliming forms. Understanding the latency time as a production of the social bow, it cogitates that new transformations in the culture can extinguish it while constituent time. It points that breakings in the sustentation of the psychic work of the latency appear in some clinical formations as the intellectual inhibition and the pertaining to school phobia.
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