A novel aproach to active surge control is presented. A centrifugal compressor driven by an electrical motor is studied, and the drive itself is used for surge control, thus elliminating the need for additional actuators. It is shown that by using the rotational speed of the motor as control, previous unstable operating points to the left of the surge line can be made globally exponentially sta...

In this paper, we present a cable mechanism which synthesizes a nonlinear rotational spring from a linear spring. The nonlinearity is realized by winding the cable around a spool which has a varying radius. We show that for a given nonlinear torque profile (synthesis objective) there is an explicit geometric expression of the shape of the spool which synthesizes this profile. We present the geo...

This paper considers power generation control in variable-speed variable-pitch horizontal-axis wind turbines operating at high wind speeds. A dynamic chattering torque control and a proportional integral (PI) pitch control strategy are proposed and validated using the National Renewable Energy Laboratory wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. Valid...

The spin-orbit problem in celestial mechanics describes the motion of an oblate satellite moving on a Keplerian orbit around a primary body. We apply the conjugate points criterion for the nonexistence of rotational invariant tori. We treat both the conservative case and a case including a dissipative effect modeling a tidal torque generated by internal nonrigidity. As a by-product of the conju...

We present the results of the fast electro-optic response of multiwalled carbon nanotubes (MWCNTs)-doped deformed helix ferroelectric liquid crystal (DHFLC). The fastening of the response in MWCNTs-doped DHFLC has been attributed to the decrease in rotational viscosity and increase in anchoring energy. The decrease in the former is due to the experience of the torque both by MWCNTs and DHFLC an...

We consider stochastic rotational dynamics of a macrospin at a constant temperature, in presence of an external magnetic field. Starting from the appropriate Langevin equation which contains multiplicative noise, we calculate entropy production (EP) along stochastic trajectories, and obtain fluctuation theorems. The system remains inherently out of equilibrium due to a spin torque supporting az...

In this contribution we present the novel electro-pneumatic adaptable impedance actuator (EPAIA) consisting of a brushless DC-motor and a rotational pneumatic actuator, applied in series to the gear train. The pneumatic actuator is employed as a pneumatic torsional spring with a continuously adaptable stiffness, controlled by air inflow and pressure control. Thus, a rotary variable stiffness ac...

OBJECTIVE The purpose of this study was to evaluate the influence of 350-rpm rotational speed on the failure incidence of ProFile nickel-titanium rotary instruments (PRI) when used by an experienced operator in conjunction with different motors. STUDY DESIGN Extracted human mandibular and maxillary first and second molars demonstrating curvatures greater than 25 degrees were used. PRI sizes 4...

In this paper a novel rotational actuator with adaptable compliance is presented. First the importance of adaptable compliance for bipedal walking is explained, and then a number of comparable designs are given with their possible drawbacks. The MACCEPA concept and design is described in detail. The formula to calculate the generated torque is derived. It is shown, depending on the design param...

Many patents have suggested that spinning the aircraft wheel before touchdown would lessen tyre wear as indicated by landing smoke and rubber deposites on the runway caused by skidding wheel at the point of impact. In this paper, the required torque to spin the aircraft wheel at approach speed has been calculated using ANSYS Workbench CFX, which is used to determine the wheel aerodynamic forces...