Lucian Nascutiu - Academia.edu (original) (raw)

Papers by Lucian Nascutiu

The resonant behaviour of voice coil actuators driven by fast changing signals limits their appli... more The resonant behaviour of voice coil actuators driven by fast changing signals limits their application in hydraulic servo valves. A very good damping, precision and the ability to dynamically overcome the effects of flow forces are some special requirements. The paper attempts to propose some control strategies and solutions to reduce the effects of raising impedance near the resonant frequency, thus improving the damping, which allows further enhancements in bandwidth. Theoretical models and simulation results are presented and discussed and some recommendations are proposed. The parameters used in simulation correspond to those of an already developed and tested voice coil prototype.

ABSTRACT This paper presents the theoretical fundaments and the numerical simulation for the line... more ABSTRACT This paper presents the theoretical fundaments and the numerical simulation for the linearization of the nonlinear model of the double (single)-rod hydraulic actuator through feedback. The paper presents the hydraulic model, the equivalent hydraulic model, the proposed nonlinear compensator and finally the simulation results

ABSTRACT A new actuator based on voice coil motor (VCM) is proposed in this paper. The actuator, ... more ABSTRACT A new actuator based on voice coil motor (VCM) is proposed in this paper. The actuator, which uses Lorentz principle to generate force, is a new-style direct drive motor with special geometry of the magnetic circuit. A particular arrangement of three coils leads to an improvement of its transient behaviour by decreasing the electrical time constant. The use of magnetic fluids within the electromagnetic circuit yields an increase in the force factor, improves the damping, the thermal behaviour and the linearity. Easy to be controlled, with high acceleration, high speed, high force and fast actuation makes it an alternative replacement for expensive and sensitive actuators. Numerical simulations were performed with dedicated software, in order to complete experimental research and to predict some further developments.

This paper presents a modern actuator type (voice coil actuator), based on a basic electrodynamic... more This paper presents a modern actuator type (voice coil actuator), based on a basic electrodynamics principle, which use ferro fluids, for hydraulic servo valves with short transient response time. The use of ferro fluids within the electromagnetic circuit yields an increase in the force factor, improves the damping behavior and shorten the response time in transient state

Atmospheric Pollution Research, Mar 1, 2015

The study investigates the local characteristics of methane dispersion generated by the Pata Rat ... more The study investigates the local characteristics of methane dispersion generated by the Pata Rat non-compliant municipal solid waste (MSW) landfill located in vicinity of Cluj-Napoca, Romania, using a numerical model developed at The Center for Promoting Entrepreneurship in the Sustainable Development Domain, from Technical University of Cluj-Napoca. The model was applied to the analysis of the methane dispersion emitted from the landfill, in two different weather conditions. In the first case the synoptic scale effects were weak favoring local flow development, while in the second case, the synoptic scale effects were predominant. The numerical model takes into account the local orography and daytime heating. In the studied area, the topography presents substantial variation, which affects the airflow dynamics. The initial conditions are formulated using observational data, recorded at the Meteorological and Aerological Station Cluj-Napoca, as well as the Meteorological Station of Cluj-Napoca International Airport. In the first case, wind direction and intensity present diurnal variations due to the thermally induced local circulations. In air layers near the ground, up to 350-400 m, these variations are more pronounced and significantly influence the dispersion of methane. In the second case, local effects are blurred by a more intense synoptic scale circulation. In these conditions the area affected by methane dispersion is much lower as compared to the previous case. In addition, the time intervals for presence of unpleasant odor due to landfill gases were estimated. Simulation shows that the dispersion is strongly influenced by the weather conditions and local topography. The results indicate the possibility of using the model as a decisional support in assessing the applications and strategies for air pollution control on local scale. An accurate mapping of pollutant dispersion is useful both for urban planning and residential developers.

2006 IEEE International Conference on Automation, Quality and Testing, Robotics, 2006

Cavitation is one of the factors related to the fluid mechanics of mechanical heart valve closure... more Cavitation is one of the factors related to the fluid mechanics of mechanical heart valve closure, which is supposed to be instrumental in valvular prosthetics complications. The basic mechanisms of MHV (mechanical heart valve) cavitation are still unresolved, requiring more detailed research on valve closing dynamics. Such research is very important for optimizing the build of MHVs, and, in the

2006 IEEE International Conference on Automation, Quality and Testing, Robotics, AQTR, 2006

Atmospheric Pollution Research, Mar 1, 2015

2006 IEEE International Conference on Automation, Quality and Testing, Robotics, 2006

2006 IEEE International Conference on Automation, Quality and Testing, Robotics, AQTR, 2006