Speed-sensorless vector torque control of induction machines usinga two-time-scale approach

Conditions for observability of a linearized smooth-airgap induction machine model are examined, and limitations of any speed-sensorless observer scheme based on such a model are discussed. An approach for speed-sensorless flux estimation based on singular perturbation theory is developed. This approach relies on the natural time-scale separation between the electrical and mechanical dynamics of the induction machine. A full-order observer of an induction machine is presented, incorporating a correction term which has an intuitive explanation when one considers steady-state stator currents. Using singular perturbation theory, convergence of the observer is shown for all open-loop stable operating points of the induction machine, with the exception of DC excitation. Sensitivity of the observer to parameter deviations is discussed. Experimental results are presented confirming the validity of the above approach     

A 4-/spl mu/a quiescent-current dual-mode digitally controlled buck converter IC for cellular phone applications

This paper describes a dual-mode digitally controlled buck converter IC for cellular phone applications. An architecture employing internal power management is introduced to ensure voltage compatibility between a single-cell lithium-ion battery voltage and a low-voltage integrated circuit technology. Special purpose analog and digital interface elements are developed. These include a ring-oscillator-based A/D converter (ring-ADC), which is nearly entirely synthesizable, is robust against switching noise, and has flexible resolution control, and a very low power ring-oscillator-multiplexer-based digital pulse-width modulation (PWM) generation module (ring-MUX DPWM). The chip, which includes an output power stage rated for 400 mA, occupies an active area 2 mm/sup 2/ in 0.25-/spl mu/m CMOS. Very high efficiencies are achieved over a load range of 0.1-400 mA. Measured quiescent current in PFM mode is 4 /spl mu/A.     

Linear array of woodpile EBG sectoral horn antennas

A technique is described for creating linear array antennas that conform to the natural stacking sequence of the woodpile electromagnetic bandgap (EBG) material. Each element in the linear array consists of a woodpile EBG sectoral horn antenna. The electromagnetic confinement mechanism within each horn antenna relies wholly on the 3-D EBG of the woodpile material. The array element has a typical sectoral horn pattern with a directional beam in one principal plane and a broader beam in the other. The bandwidth of the sectoral horn is almost equal to that of the defect EBG waveguide. Measured and theoretical results for radiation patterns, impedance bandwidth and gain of a sectoral horn antenna made from alumina are described, and theoretical results for a design made from silicon are presented. It is shown that the layer-by-layer nature of the woodpile EBG material enables sectoral horn antennas to be easily stacked together in the E-plane to create linear arrays. Analysis of the mutual coupling as a function of element separation and its effect on reflection coefficient are presented for a two-element linear array in silicon. Theoretical analyses for fixed and scanned beam linear arrays of silicon woodpile EBG sectoral horns are described and finite-difference time-domain results are compared with array theory. The fixed beam arrays are designed for high directivity while the scanned beam array enables wide angle beam steering through the use of parasitic array elements.     

Isolation and characterization of polymers in heated olestra and an olestra/triglyceride blend

High molecular weight components in thermally oxidized olestra (formerly called sucrose polyesters) and a mixture of olestra and soybean oil were characterized. The high molecular weight components of these oils were separated by preparative size exclusion chromatography and analyzed intact by mass spectrometry, infrared, and nuclear magnetic resonance spectroscopy. The materials isolated from the heated olestra were identified as olestra polymers. Materials isolated from the heated mixed oil (olestra and soybean oil) were identified as polymers of olestra and copolymers of olestra and triglycerides. Polymer linkages identified were identical to those resulting from thermal oxidation of natural vegetable oils of similar fatty acid composition.     

Cardiovascular and subjective effects of intravenous cocaine administration in humans

Nine volunteer subjects were tested with intravenously administered cocaine hydrochloride in doses ranging from 4 to 32 mg, as well as 10 mg of dextroamphetamine sulfate. Measures of cardiovascular and subjective effects were made. Generally parallel dose-effect functions were obtained for heart rate, blood pressure, Addiction Research Center Inventory scores, Profile of Mood Scales, and subject ratings. A substantial effect on each of these variables was recorded after 8 mg of cocaine. The increase continued and peaked at approximately 16 mg after which it usually leveled off. Ten milligrams of dextroamphetamine generally had an effect comparable to 8 to 16 mg of cocaine.     

Mechanosensitive afferent units in the hypogastric nerve of the cat

1. Recordings have been made from ninety single afferent units in the hypogastric and lumbar splanchnic nerves of the cat. 2. The majority of units examined had properties similar to those previously described in the splanchnic nerve: they were slowly adapting mechanoreceptors with one to six punctate mechanosensitive sites distributed mainly along blood vessels as they approached the viscera in peritoneal ligaments; they had a wide range of mechanical thresholds and conduction velocities in the range 0.5-24 m s-1. 3. Receptive fields were found over the bladder base or its peritoneal ligaments or both, on the uterus or broad ligament or both, on the colon or mesocolon or both, and in association with the ureter, vas deferens, prostate or pelvic fat pads. 4. Discharges from afferent units associated with the bladder were investigated during spontaneous (or reflex) bladder contractions, passive distensions, and tetanic contractions induced by electrical stimulation of the sacral spinal cord. The mean spike rates of the adapted (tonic) discharges, observed during distensions and induced tetani, differed over part of the range of intravesical pressures examined. Their behaviour is discussed in relation to the concept of 'in series' tension receptors within the bladder wall.     

A simple device to obtain a pulsatile flow. Application to the vascular perfusion of dogs isolated intestinal segments

A simple device allowing a pulsatile flow to be obtained in isolated organ perfusion has been developed and applied to the vascular perfusion of isolated canine jejunal segments. The principle of the device consists of superimposing on a constant pressure produced by a roller pump, a pulsatile pressure of which the amplitude, frequency, and shape of the pulses can be adjusted separately and independently of the mean pressure value. The role of the arterial pulse in intestinal vascular perfusion has been studied by comparing the hemodynamic and metabolic behavior during alternate periods of pulsatile and nonpulsatile pumping. While no striking change in vascular resistance was observed, the O2 consumption was significantly increased under pulsatile flow. These results testify to better metabolic conditions and enhanced organ functions under pulsatile pumping and also argue for improved intestinal microcirculation despite the constancy of the vascular resistance.     

Association of hemoglobin Saint Etienne (alpha2beta295F8 His replaced by G1n) with hemoglobins A and F. Synthesis and subunit exchange in vitro

The unstable hemoglobin (Hb) Saint Etienne (alpha2beta295F8 His replaced by G1n) (betaSE) was found in the red blood cells of an 8-year-old boy. The composition of this hemoglobin was 26% Saint Etienne, 52% A, 3% A2 and 19% HbF. Studies of hemoglobin synthesis indicate: a) a balanced synthesis of alpha and non-alpha chains (alpha=betaA + betaSE + gamma), b) an increased pool of free alpha hemoglobin chains, and c) a rapid exchange of alpha chains between this pool and HbSE. The alpha chain pool resulted from the dissociation of HbSE and the greater instability of betaSE chains than alpha chains upon heating. Hemoglobin F is of the fetal type and is heterogeneously distributed among the red cells. Furthermore, two populations of red blood cells could be separated according to their i antigen content. Analysis of the hemoglobins revealed a heterogeneous distribution. Thus, F hemoglobin was preferentially associated with cells having low i antigen level, while Saint Etienne hemoglobin was increased in cells having a high i antigen level. HbF and HbSE were not present in the parents of the propositus. Study of the genetic markers confirmed the filiation. The parents were normal upon clinical and hematological examination; they exhibited a normal pattern and synthesis of hemoglobin. The Hb Saint Etienne case is compared with Hb Istanbul, which in spite of the same amino acid substitution is not associated with increased HbF level.