an ideal orthodontic force system should exert continuous light force. thus, many efforts have been made to improve the memory characteristics of elastomeric chains. the aim of this study was to compare elastomeric chains (ecs) claimed by their manufacturers to offer high memory with traditional ones according to their force-extension diagrams.in this in-vitro study, ecs were divided into six g...

Paralysis in man and the domestic fowl caused by "ToCP" (tri-cresyl phosphate, tri-tolyl phosphate or TTP) is reviewed, and the search for a non-toxic plasticizer derived either from TTP or tri-xylenyl phosphate (tri-dimethylphenyl phosphate or TXP) is described. It had been previously shown that the ortho-tolyl esters are toxic but we found that their removal does not make the mixture non-toxi...

A method of actively maintaining voltage margin in field oriented induction machine controllers is proposed. A voltage margin controller is developed that rejects dc link and load disturbances such that current regulation and field orientation is maintained. In addition, the voltage margin controller coupled with rotor flux oriented control is shown to provide maximum torque capability equivale...

The poor quality of voltage and current of a conventional inverter fed induction machine is due to the presence of harmonics and hence there is significant level of energy losses. The nine level inverter is used to reduce the harmonics. The inverters with a large number of steps can generate high quality voltage waveforms. The concept of multilevel inverters, introduced about 20 years ago entai...

This paper presents a predictive torque and flux control algorithm for the synchronous reluctance machine. The algorithm performs a voltage space phasor pre-selection, followed by the computation of the switching instants for the optimum switching space phasors, with the advantages of inherently constant switching frequency and time equidistant implementation on a DSP based system. The criteria...

Power systems are subjected to small–signal oscillations that can be caused by sudden change in the value of large loads. To avoid the dangers of these oscillations, the Power System Stabilizers (PSSs) are used. When the PSSs can not be effective enough, installation of the Thyristor–based compensators to increase the oscillations damping is a suitable method. In this paper, a Static Synchronou...

In the conventional structure of the wind turbines along with the doubly-fed induction generator (DFIG), the stator is directly connected to the power grid. Therefore, voltage changes in the grid result in severe transient conditions in the stator and rotor. In cases where the changes are severe, the generator will be disconnected from the grid and consequently the grid stability will be attenu...

The present paper formulates the state space modeling of doubly fed induction generator (DFIG) based wind turbine system for the purpose of the stability analysis. The objective of this study is to discuss the various modes of operation of the DFIG system under different operating conditions such as voltage sags with reference to variable wind speed and grid connection. The proposed control met...

Conduction spectroscopy measures the current I through a nanosystem as a function of the voltage V between two electrodes. The differential conductance, dI/dV, has peaks that can be assigned to resonance conditions with different electronic levels of the system. Between these increments, the current has roughly constant plateaus. We discuss how measurements of the current vs. voltage can be use...