Разработка математической модели автономной пневматической подвески сиденья водителя транспортного средства с прямым включением виброзащитного модуля

Предложена нелинейная математическая модель автономной пневматической подвески сиденья водителя транспортного средства с прямым включением виброзащитного модуля. На основании этой модели определены упругая сила и сила демпфирования колебаний автономной виброзащитной системы. Методом численного интегрирования получены переходные процессы (свободные колебания), вызванные кратковременным приложением усилия на сжатие подвески и последующего снятия приложенного усилия. Получено не только качественное, но и количественное согласование теоретических и экспериментальных результатов изменений во времени основных параметров пневматической подвески.The nonlinear mathematical model of an independent pneumatic suspension of the vehicle driver seat with direct inclusion of the vibroprotection module is proposed. On the basis of this model an elastic force and a force of independent vibroprotection system vibrations damping is defined. Transient processes (free vibrations) caused by the short-term action to the suspension compression and further force removal are obtained by the method of numerical integration. Not only qualitative but also quantitative correspondence of theoretical and experimental results of main pneumatic suspension parametres changes is obtained

Evolutions of personal networks and life events

http://www.sciencedirect.com/science/journal/03788733International audienceNetworks of personal relations evolve over time. They reflect and go with processes of socialization. Their history and dynamics contribute to their present structure. The number of people involved in them and their composition change, as does the quality of the links that constitute them. What life events might influence these changes, or possibly even explain them? Drawing on a qualitative survey of a panel of 66 young people living originally in Normandy (France), who were questioned every three years, we attempt here to find a relation between the evolution of their personal networks and the events marking their entry into adult life. Do their networks expand or contract, do they move regularly or in stages? What are the links that appear, disappear or change? What events are likely to influence changes in these links and in the networks as a whole? We begin by examining the changes in the young people's networks during the survey's three waves. We then identify the life events that took place in the intervals, focusing in particular on entry into the labour market, geographical mobility, setting up house with a partner and the birth of children in the household. This enables us to advance some hypotheses about the impact of these events on the evolution of networks and to illustrate our argument with a few significant examples

Transitions vers la vie adulte et origines sociales : une enquête longitudinale en France

Claire Bidart et Daniel Lavenu reviennent sur la notion de transition en questionnant sa borne supérieure : vers quoi avance la jeunesse ? Qu'est-ce que l'entrée dans l'état d'adulte ? Afin de contribuer à éclairer cette fausse évidence, ils ont posé à plusieurs reprises la question à un panel de jeunes Français : seconsidèrent-ils comme adultes, et pourquoi? Ils analysent alors les attributs de ces jeunes, mais surtout les argumentaires qu'ils mobilisent. Les jeunes issus des classes populaires et les jeunesissus des classes supérieures montrent des «manières » différentes de se dire adulte (ou non adulte). Si certains se déclarent adulte «de fait », d'autres attendent d'être adulte «pour soi». Les transitions apparaissent ici souvent partielles et relatives aux situations et aux contextes relationnels. La question de l'individualisation des parcours est discutée à la lumière de ce clivage bien social