Backstepping design for controlling electrohydraulic servos

The backstepping technique is one of the tools which provides control Lyapunov functions (CLFs) and, therefore, control laws for automatic systems. In this paper, the backstepping design for position and force nonlinear electrohydraulic servos is investigated. Three control laws ensuring the asymptotic stability of references tracking are obtained by constructing CLFs on the errors concerning the state variables and theirs desired values. The possibility of converting a position servo into a force servo, with only minimal hard modification, is proved. An approach based on partitioning the state system into two subsystems—a first one stable, and a second one taken as framework of control synthesis by backstepping technique—was developed and used. Using as reference point a flight controls hydromechanical servo, numerical simulations were reported from viewpoint of servo time constant performance. Certain conjectures, concerning the behaviour of systems mathematical models, in connection with mathematical methodologies of control synthesis operating on them, are finally stressed.     

Higher education reform in Romania

This paper reviews the crisis in Romanian universities since the country's political transition in 1989, and describes the government's strategy for revitalizing the higher education system. Attention is drawn to the expansion of access to higher education, the dramatic increase of enrollments in social science fields, the spontaneous establishment of private higher education institutions, and to the many difficulties institutions are experiencing in coping with these changes especially because of resource constraints. Comprehensive reform of the role of the state in the financing and governance of higher education are proposed. The government's reform strategy involves accreditation of public and private institutions, establishment of open transparent mechanisms for allocating institutional and research funding, as well as changes in the structure of academic employment. Successful implementation will require strengthening the fragile management capacity of the Ministry of Education and the higher education institutions.     

Restless youth: emigration and enterprise in Romania

The political changes in Romania after 1989 were followed by structural changes that affected all areas of social, economic, political, and cultural life. The transition from a ‘closed’ to an ‘open’ society has been difficult for East European countries, as the creation of institutions oriented towards competition and diversity has not led to an instantaneous change in mentalities and social routines. Decades of communist education in the ‘spirit of modesty’ ensured that aspirations did not transgress ideological boundaries, and this is essential to an appreciation of the gap between social aspirations and systemic functionality after 1990.

Extensive economic reorganization has had a direct effect on the education system, with some as yet unnatural changes. New occupations and fields of activity have emerged, for which existing qualifications are proving inadequate. At the same time, relative to the pre‐1989 occupational structure, the importance granted to qualifications has dramatically decreased. If the outlets for expressed ideals and aspirations are insufficient, the surplus of qualifications tends to ‘drain’ towards less socio‐economically closed environments.