Abstract: A power conversion system having a DC power distribution bus includes multiple power converters connected to the DC power distribution bus with modulation frequencies synchronized so that providing phase shifts between the different modulations has the effect of compensating voltage and current ripples, e.g., reducing voltage fluctuations, across the DC bus. Power conversion may be controlled using space vector modulation implemented, for example, by any of a variety of pulse width modulation schemes. Phase shifts in which nulls of the modulation cycles of different converters do not overlap (in the time domain) may be particularly effective for DC bus voltage ripple compensation. The novel method for DC bus voltage ripple compensation may be implemented by programming a digital signal processor to control the power converters.

Abstract: An apparatus configured to facilitate removal of a growing medium and the root structure of a plant surrounded by the growing medium while maintaining the integrity of the growing medium and root structure. The apparatus comprises a U-shaped connector body having a first blade and a second blade extended down there from. The first blade has a first end and a second end to which the first end of the U-shaped connector body is connected. The connection of the first blade to the U-shaped connector body is at an angle causing the first blade to extend downward when the U-shaped connector body is positioned horizontally. The second blade has a first end and a second end to which the second end of the U-shaped connector body is connected. The connection of the second blade to the U-shaped body is at an angle causing the second blade to extend downward when the U-shaped connector body is positioned horizontally.

Abstract: Overspeed protection of sensorless electric drives is needed in the aerospace industry. Methods for overspeed protection may include software implementations, hardware implementations or combinations thereof. Typical high-speed rotating machinery is designed to sustain overspeed operation of up to 50% beyond maximum normal operation. This requirement leads to substantial penalties in weight and volume. The methods of the present invention may allow for an opportunity to reduce this overspeed design to about 5 to 15%, typically about 7%.

Abstract: Overspeed protection of sensorless electric drives is needed in the aerospace industry. Methods for overspeed protection may include software implementations, hardware implementations or combinations thereof. Typical high-speed rotating machinery is designed to sustain overspeed operation of up to 50% beyond maximum normal operation. This requirement leads to substantial penalties in weight and volume. The methods of the present invention may allow for an opportunity to reduce this overspeed design to about 5 to 15%, typically about 7%.

Abstract: A power conversion system having a DC power distribution bus includes multiple power converters connected to the DC power distribution bus with modulation frequencies synchronized so that providing phase shifts between the different modulations has the effect of compensating voltage and current ripples, e.g., reducing voltage fluctuations, across the DC bus. Power conversion may be controlled using space vector modulation implemented, for example, by any of a variety of pulse width modulation schemes. Phase shifts in which nulls of the modulation cycles of different converters do not overlap (in the time domain) may be particularly effective for DC bus voltage ripple compensation. The novel method for DC bus voltage ripple compensation may be implemented by programming a digital signal processor to control the power converters.

Abstract: A motor controller for brushless motors operates an inverter in a current-controlled mode for low motor speeds and in a voltage-controlled mode for high motor speeds. By switching from the current-controlled mode to the voltage-controlled mode at higher speeds, the motor can be designed at maximum efficiency, and minimum weight, cost and volume.

Abstract: A gas turbine engine blade has an abrasive material tip with a fused superalloy matrix and evenly distributed ceramic particulate. The matrix will have a desirable metallurgical structure characterized by fine dendrites and remanants of the original powder metal structure from which it was made. Due to the fusion of the tip, the peripheral edge will tend to be curved. To lessen the effect of thermal strains on such an abrasive tip, a sheath of a superalloy, such as a portion of the turbine blade substrate, extends along the side of the abrasive. The sheath may be present only in the thicker leading edge part of the blade airfoil.

Abstract: a method of ion analysis and detection of weakly dissociated anions or cations in an eluent by first separating such ions on a chromatographic separation medium by ion exclusion chromatography or mobile phase ion exclusion chromatography. The eluent include an acid or base with a co-ion of the same charge as the ions to be separated, such co-ions being in the hydronium or hydroxide form. In one embodiment the effluent from the separation medium is contacted with one side of an ion-exchange membrane having exchangeable ions of opposite charge to the ionic species. The opposite side of the membrane includes a regenerant with salt-forming suppression ions capable of forming a weakly conducting salt with the co-ions. Then the separated ionic species are detected preferably by a conductivity detector. In another embodiment, the membrane is replaced by a resin bed with ion-exchanging sites of opposite charge to the co-ions. There, co-ions form a suppressed salt with the exchangeable ions.

Abstract: Method and apparatus for quantitative analysis of weakly ionized anions (e.g. carboxylates) or cations (e.g., organic amines). For anion analysis, the sample and a strong acid (e.g., HCl) eluent are passed through an ion exclusion chromatography column (cation exchange resin) to resolve the weak anions while eluting the strong anions in the void volume peak. HCl is stripped on an ion exchange stripper column in the silver ion form and the effluent is directed through a conductivity cell and associated readout for detection. For weak cation analysis, the sample and a strong base (e.g., Ba(OH).sub.2) eluent are passed through an ion exclusion chromatography column (anion exchange resin) to resolve the weak cations while eluting the strong cations (e.g., Na.sup.+, K.sup.+) in the void volume peak. Ba(OH).sub.2 is stripped on an ion exchange stripper column in the sulfate ion form and the effluent is directed through a conductivity cell and associated readout for detection.

Abstract: In a liquid chromatography system, the effluent from the chromatographic column is passed through a detector flow cell, which is packed with a stationary phase that is adsorptive of the sample species to be detected. Detection of the sample species adsorbed at the stationary phase is effected by measuring fluorescence emitted from such species in response to electromagnetic radiation incident thereon at the flow cell. The fluorescing species, which are in equilibrium between the stationary phase and the mobile phase in the flow cell when fluorescence is being measured, can be detected at lower concentration thresholds than when the fluorescing species are in equilibrium only with the mobile phase.

Abstract: A device for controlling the rotational speed of a friction welder as a function of the combined length of the pair of parts to be welded, within predetermined tolerances, so as to produce welded pieces of uniform length in spite of minor variations in the lengths of the parts. Logic and sequencing circuitry specially adapted to carry out this function at minimum cost is also described.