Showing papers on "Decoupling (electronics) published in 1989"

Observation of the Temporal Decoupling Effect on the Macroscopic Quantum Tunneling of a Josephson Junction

Abstract: We have measured the Macroscopic Quantum Tunneling (M.Q.T.) rate out of the zero voltage state of a Josephson junction shunted by a delay line terminated by a resistor. As the length of the line is increased in situ, thereby increasing the delay with which the resistor damps the junction, the M.Q.T. rate increases until it almost recovers its value in the absence of damping: This constitutes the temporal decoupling effect. We compare our results to the theoretical predictions.

Electronically controlled automatic transmission

Abstract: An electronically controlled automatic transmission including an automatic gear shift for changing the gear ratio according to the coupling/decoupling of the brake and clutch, a hydraulic switch for controlling a hydraulic pressure exerted on the brake and clutch, a timer for setting a time of coupling/decoupling of the clutch and brake during a shifting period, a detector for detecting vehicle information, a time correcting device for correcting the set time according to the detected vehicle information, and an electronic control device for driving the hydraulic switch and for changing the state of coupling/decoupling. The electronic control device having a temperature detector for detecting the temperature of the working fluid of the hydraulic switch, and a feedback stop device for stopping the correction by the time correcting device when the temperature detector detects that the temperature of the working fluid is below a predetermined temperature.

Short-resistant decoupling capacitor system for semiconductor circuits

Abstract: A decoupling capacitor system for improving the reliability of digital logic circuit boards such as single inline memory modules which use surface-mount decoupling capacitors. The system comprises one or more units of two or more series-connected capacitors connected between the chip supply voltage (Vcc) input and the chip ground (Vss) connection. Given no change in the reliability of the individual capacitors, the reliability of a circuit board can typically be improved by several order of magnitude.

Increased rf power absorption in MR imaging due to rf coupling between body coil and surface coil.

Abstract: Fears have been voiced that excessive tissue heating could occur in the event that first, a surface coil is placed with its axis parallel to the transmitting rffield leading to a maximal coupling of the two coils and second, the decoupling circuit of the surface coil breaks down. To avoid an rf coupling of the transmitting body coil to the receive-only surface coil, conventionally applied surface coils are equipped with an active electronic rf decoupling circuit. In extensive worst-case experiments on phantoms we have shown that no tissue heating occurs for surface coils which are equipped with semiconductor varicap diodes for tuning and matching. These coils should be safe for patient applications even if the decoupling circuit fails. Surface coils equipped with mechanically variable capacitors are generally passively decoupled. To simulate the worst-case situation phantom experiments were performed in which a surface coil of this type having no passive decoupling circuit was coupled to the transmitter coil by its geometric position. Theoretical calculations, in agreement with the experimental results achieved during a 15-min measurement in a 1.5-T MRI whole-body imager, show that a significant rfpower deposition in the tissue underneath the coil wire occurs, leading typically to a local specific absorption rate of 24 W /kg and a local temperature rise of 52°C. © 1989 Academic Press, Inc.

Analysis and reduction of sense-amplifier offset

Abstract: The offset of sense amplifiers used for dynamic RAMs (DRAMs) at the megabit level is investigated. An analytic expression which permits an easy calculation of the different offset contributions is derived. The influence of the transistor size and the effect of decoupling devices between bit lines and amplifier are discussed. The sensitivity can be improved if a preamplifier is used. Here, a circuit that doubles the sense signals by switching two capacitors between bit line and reference line is presented. The performance of the preamplifier has been verified through its realization on a test chip. >

Three reservoir capacitor charge pump circuit

Abstract: A charge pump circuit operates from a voltage provided on an input rail at a first potential relative to a reference potential rail and that provides second and third potentials relative to the reference potential rail on first and second output rails, respectively. The charge pump circuit includes first, second and third charge reservoir capacitors, an oscillator and control logic circuit for providing timing control signals, and a switch network responsive to the timing control signals for coupling the first, second and third capacitors in a plurality of configurations. In transitioning between these configurations, the switch network provides for the decoupling of the first capacitor from between the input rail and the reference potential rail prior to enabling the second configuration and from between the second output rail and the input rail prior to enabling the first configuration, and for the decoupling of the second capacitor from between the first output rail and the reference potential rail prior to enabling the third configuration and from between the reference potential rail and the second output rail prior to enabling the first configuration.

MR examination apparatus comprising a circuit for decoupling the two coil systems of a quadrature coil arrangement

Abstract: An MR examination apparatus has a quadrature coil arrangement which consists of two coil systems and a circuit for decoupling the two coil systems In such an MR examination apparatus the decoupling between the coil systems is improved in that the circuit comprises a variable capacitor which connects one coil system to the other

Three reservoir capacitor

Abstract: A charge pump circuit operates from a voltage provided on an input rail at a first potential relative to a reference potential rail and that provides second and third potentials relative to the reference potential rail on first and second output rails, respectively. The charge pump circuit includes first, second and third charge reservoir capacitors, an oscillator and control logic circuit for providing timing control signals, and a switch network responsive to the timing control signals for coupling the first, second and third capacitors in a plurality of configurations. The switch network also provides for the decoupling of the capacitors from between the input rail and the reference potential rail between transitions of these configurations.

Realization of a control device for a robotic manipulator based on nonlinear decoupling and sliding mode control

Abstract: The realization of a control system for a robotic manipulator is described. The control scheme is subdivided into two hierarchical levels: the inner level performs the output decoupling of the joint dynamics: the outer one computes the desired accelerations. The decoupling, obtained by a simplified compensator and a sliding mode technique, is realized by means of analog circuits, while the tracking of the desired trajectories is performed by a digital computer. The description of measurements and tests is included. >

Apparatus for carrying out decoupling control of a t-die

Abstract: In an apparatus for use in carrying out decoupling control of a T-die which has a pair of lip portions with a gap extended between the lip portions and with the lip portions divided into a plurality of zones individually driven by driving devices, respectively, a processing circuit individually controls the driving devices by the use of a predetermined decoupling control algorithm. The predetermined decoupling algorithm is given by a plurality of desired displacement vectors of the gap for the respective zones and a decoupling control matrix defined by inverse number of products of a command value/driving pressure converting matrix (Kp) and a driving pressure/ displacement converting matrix (Kα). Alternatively, the decoupling control matrix is repeatedly modified with time to decrease a difference between the desired gap displacement (Δy) and the measured gap displacement (Δym). Each command voltage value vector Δu of the command value/driving pressure converting matrix is compensated by the use of a figurative inherent error of the lip structure.

Adaptive decoupling control of mimo systems

Abstract: This paper describes a new adaptive controller for MIMO systems. The resulting closed-loop system will be stable and decoupled. The system to be controlled can be linear, non-minimum phase and/or unstable. The interactor matrix need not be known beforehand. Instead of employing the certainty equivalence principle to design the adaptive controller, a special controller design procedure is used. By using this special scheme, the computation time required for controller design will be drastically reduced. Moreover, the boundedness of the controller parameters is automatically ensured. This is a desired property which is useful in stability analysis. The steady state performance of the controller designed by the proposed method will be the same as that of controllers designed using the certainty equivalence principle. Approximate decoupling can be achieved by underestimating the degree of the decoupling matrix without affecting the stability of the system. To achieve decoupling, we need to specify the denominator of the closed-loop transfer function matrix of the system which is assumed to be in the form T(q−1) = t(q−1)I where the polynomial t(q−1) is assumed to be monic and stable. Global stability of the adaptive system is obtained for deterministic systems. A simulation example is presented to demonstrate this control scheme.

A safety system for machinery having exposed moving parts

Abstract: A safety system for machinery, such as an agricultural baler or tractor, having exposed moving parts, comprises a mechanism (67), for deactivating the drive means and/or (66) for decoupling the machinery from the drive means, at least one sensor device (55, 56) at an exposed location in the vicinity of the moving parts of the machinery and a detector circuit (61, 62, 63, 70, 85) operable to trigger the said deactivation or decoupling means (67, 66) upon actuation of the sensor device (55, 56), the sensor device comprising an exposed housing which can be triggered simply by striking or pressing with the hand or any part of the body. Means (70) may be provided for discriminating between deliberate emergency operation of a sensor (55, 56) and an accidental impact such as may occur during normal use of the machinery.

Speed and efficiency control of induction motors via asymptotic decoupling

Abstract: An attempt is made to control induction motors with high power efficiency as well as high dynamic performance by utilizing recently developed nonlinear feedback control techniques. The controller consists of three subcontrollers: a saturation current controller, a decoupling controller, and a well-known flux simulator. The decoupling controller decouples rotor speed (or motor torque) and rotor flux linearly. The controller does not need the transformation between a d-q synchronously rotating frame and an x-y stator-fixed frame. It is computationally quite simple and does not depend on the rotor resistance, which varies widely with the machine temperature. Performance analysis and simulation results are presented. >

Three-phase converter

Abstract: OF THE DISCLOSURE A method of operating a three-phase converter to produce a signal at an output frequency by decoupling and digitally sampling inverter input signals and load voltage signals and feeding the resultant phase signals back into the inverter. The phase voltages activate switching elements in the inverter to switch signals a plurality of times within one cycle of the output frequency thus changing electrical power at a first frequency, including direct current, to A.C. power at the output frequency.

A method of decoupling a three-phase converter

Abstract: A method of operating a three-phase converter to produce a signal at an output frequency by decoupling and digitally sampling inverter input signals and load voltage signals and feeding the resultant phase signals back into the inverter. The phase voltages activate switching elements in the inverter to switch signals a plurality of times within one cycle of the output frequency thus changing electrical power at a first frequency, including direct current, to A.C. power at the output frequency.

Local coil for NMR tomography - has PIN=diode as separating diode in both upper and lower U=shaped parts for decoupling from whole body antenna in receiving circuit

Abstract: The lower part for special applications is connectable via plug (15-18) couplings to the upper part. Each part contains at least one h.f. coil (6,7;13,14). The lower part has an equalising and tuning circuit (30,31,34) for use by both parts. For decoupling the local coil from a whole body antenna, a PIN-diode (4,9) serving as a separating diode, is provided in the receiving circuit of both parts. A control current for conductive control of the PIN diodes is lead over both of them in series if the upper part is plugged in but only over that (4) of the lower part if not plugged in. ADVANTAGE - Simple control possibility for decoupling local coil whether upper part is plugged in or not.

Differential operational amplifier with common mode feedback

Abstract: A circuit configuration includes a differential operational amplifier having differential input terminals and differential output terminals. A common mode feedback circuit sets a direct voltage operating point of the output terminals. A reference voltage terminal connected to the output terminals supplies a reference voltage. Two pairs of operating point transistors of complementary conductivity types have control terminals and have output circuits connected in series at a respective connection point for each pair. Each of the connection points is connected to a respective one of the output terminals. A reference current source controls the operating point transistors in parallel. First coupling capacitors are each connected between a respective one of the output terminals and a respective one of the control terminals of an associated operating point transistor of one conductivity type. The common mode feedback circuit includes second coupling capacitors and a remainder of the common mode feedback circuit. The second coupling capacitors are each connected between a respective one of the output terminals and a respective one of the control terminals of an associated operating point transistor of a conductivity type complementary to the one conductivity type, for decoupling the first coupling capacitors and the associated operating point transistors from the remainder of the common mode feedback circuit.

Decoupling fuzzy relational systems-an output feedback approach

Abstract: The output feedback decoupling problem for fuzzy relational dynamic systems is considered. The structure of a decoupling controller is proposed, and some results concerning the solution of the decoupling problem are presented in terms of the proposed theorems. The essential difference between decoupling a fuzzy system and a nonfuzzy one is that, in the former, all the variables are characterized by their membership functions. >

Power control experiments using a PWM GTO thyristor converter in a 1 MJ superconducting magnetic energy storage system

Abstract: The outline of a 1 MJ superconducting magnetic energy storage (SMES) system and a p-q (active power-reactive power) control system using a pulse-width modulation (PWM) gate turn-off (GTO) thyristor converter is described. Results of p-q decoupling control experiments are also given. A plan is for investigating the attainment of transient and dynamic stability through the use of simulated transmission lines is described. >