Murat Dogruel

Input linearization of nonlinear systems via pulse-width control

In this note, it is shown that a general nonlinear system can be transformed to an affine nonlinear system by virtue of the use of pulsewidth control. Therefore, the combined system from the pulse width control input to the nonlinear system output behaves as an affine (linear-in-control) system. By this way, a cumbersome nonlinear system model can be transformed to a simpler linear-in-control form without increasing the system dimension; this in turn enables simpler control design. Furthermore, using this methodology, some control design methods developed only for affine systems can be adapted to general nonlinear systems.

DESIGN AND CONSTRUCTION OF A COMPUTER CONTROLLED AUTOMATIC SEQUENTIAL RAIN SAMPLER

ABSTRACT The preliminary goal of this study was to design, construct and apply a new automatic sequential precipitation sampling instrument. The proposed sequential sub-event sampler was designed in two sections: mechanical and electronical sections. The mechanical part includes a series of 100 mL sampling bottles on it, and a metallic body. The electronic part is composed of digital and analog sensors, various electronic material and a computer as the main controller of the system. Commands generated by the computer control the system, and the sub-event sampling period and the volume can be adjusted. Besides the volume and time controlled sampling, intelligent control and sampling is possible by developing adequate algorithms. Since the system consists of automatic sensors that can be controlled by the computer, anthropogenic errors in sampling are expected to be kept at minimum. The proposed instrument is open to development and additions can be easily made. The application phase includes collection of sequential precipitation samples, their analysis and an attempt to determine the sources of environmental pollution. The developed equipment was used to collect samples for five rain events that took place on 7 September 2007. The samples were analyzed for Na+, Mg2+, Ca2+ and K+ to obtain the temporal variation of the chemical composition during the precipitation event.

A microcontroller implementation of harmonic control arrays method

Harmonic Control Arrays (HCA) is a method based on adjusting the harmonic components of the control signal to minimize the error signal for systems with periodic references and disturbances. In this study the results of a discrete-time implementation of HCA with a microcontroller as the control unit has been represented. A low-pass filter (LPF) and a nonlinear electronic circuit has chosen as the plant, and a periodic sinusoidal reference signal have been applied on it.

Indirect control of single-phase active power filters using harmonic control arrays

The ever increase of nonlinear loads in electric distribution networks causes many problems due to the high level of harmonic currents. This paper proposes a new technique for controlling a single phase shunt active power filter based on a selective compensation using the newly developed technique of harmonic control arrays. Simulation results confirm the appropriate selective harmonic compensation performance under different operating conditions.