Abstract: Methods and apparatus for controlling a polyphase motor in implantable medical device applications are provided. In one embodiment, the polyphase motor is a brushless DC motor. The back emf of a selected phase of the motor is sampled while a drive voltage or the selected phase is substantially zero. Various embodiments utilize sinusoidal or trapezoidal drive voltages. The sampled back emf provides an error signal indicative of the positional error of the rotor. In one embodiment, the sampled back emf is normalized with respect to a commanded angular velocity of the rotor to provide an error signal proportional only to the positional error of the motor rotor. The error signal is provided as feedback to control a frequency of the drive voltage. A speed control generates a speed control signal corresponding to a difference between a commanded angular velocity and an angular velocity inferred from the frequency of the drive voltage.

Abstract: Methods and apparatus for controlling a polyphase motor in implantable medical device applications are provided. In one embodiment, the polyphase motor is a brushless DC motor. The back emf of a selected phase of the motor is sampled while a drive voltage of the selected phase is substantially zero. Various embodiments utilize sinusoidal or trapezoidal drive voltages. The sampled back emf provides an error signal indicative of the positional error of the rotor. In one embodiment, the sampled back emf is normalized with respect to a commanded angular velocity of the rotor to provide an error signal proportional only to the positional error of the motor rotor. The error signal is provided as feedback to control a frequency of the drive voltage. A speed control generates a speed control signal corresponding to a difference between a commanded angular velocity and an angular velocity inferred from the frequency of the drive voltage.

Abstract: A method for providing files to a remote node including the steps of determining whether bandwidth is available for transmitting across a communications link a file requested by a remote node, reserving bandwidth for the requested file if bandwidth is determined to be available, and opening the requested file for transmission only if bandwidth is reserved. In addition, an apparatus for providing files to a remote node including apparatus for determining whether bandwidth is available for transmitting across a communications link a file requested by a remote node, apparatus for reserving bandwidth for the requested file if bandwidth is determined to be available, and apparatus for opening the requested file for transmission only if bandwidth is reserved.

Abstract: A system and method for regeneration of certain on disk dynamic control blocks for the file system after failure of access to the control blocks improves auxiliary disk storage system robustness. Regeneration of the dynamic control blocks is achieved without persistent replicas of the blocks on disk and thereby adheres to prior art disk formats. The regeneration control blocks are preferably used to support file system operation during backup of the disk, since loss of access to critical sectors for storing control blocks may portend disk storage system failure.

Abstract: A session-oriented network application dependent on reliable transport of messages on a first system communicates in a new form of connectionless, session-oriented communication called Sideband over a network with a second similar application on a second system. Sideband transport is not guaranteed; Some types of messages and those which are lost must be sent on a reliable, non-Sideband transport. The LAN application contains means to track whether Sideband is both available and enabled on its session with the second application. The application determines whether to disable or reenable the Sideband in its session based on network reliability. As Sideband is fast, but unreliable, the application must be selective about which messages to send Sideband. Messages which would change the state of the receiving system if received twice due to retry of an apparently lost message should not be sent Sideband.

Abstract: An improved pulse oximeter for the measurement of oxygen saturation in the blood, which is faster and more accurate than conventional pulse oximeter. Improved speed and accuracy is attached by elimination of normalization and feedback circuitry and the use of analog to digital converting devices having a wide dynamic range along with a sophisticated computer analysis. The instant invention eliminates inaccuracies resulting from channel matching errors, and detects and eliminates aberrant input data.

Abstract: An improved pulse oximeter for the measurement of oxygen saturation in the blood, which is faster and more accurate than conventional pulse oximeters.Improved speed and accuracy is attained by elimination of normalization and feedback circuitry and the use of analog to digital converting devices having a wide dynamic range along with a sophisticated computer analysis. The instant invention eliminates inaccuricies resulting from channel matching errors, and detects and eliminates aberrant input data.

Abstract: An improved pulse oximeter for the measurement of oxygen saturation in the blood, which is faster and more accurate than conventional pulse oximeter. Improved speed and accuracy is attained by elimination of normalization and feedback circuitry and the use of analog to digital converting devices having a wide dynamic range along with a sophisticated computer analysis. The instant invention eliminates inaccurcies resulting from channel matching errors, and detects and eliminates aberrant input data.