Showing papers on "Decoupling (electronics) published in 2012"

Simple and Efficient Decoupling of Compact Arrays With Parasitic Scatterers

Abstract: Compact arrays such as multiple antennas on a mobile terminal suffer from low efficiency and high correlation between antenna signals. In the present paper, a simple and rigorous procedure for decoupling two closely coupled antennas with a parasitic scatterer is proposed. The parasitic scatterer, which can be an additional antenna, acts as a shield between two active antenna elements. In contrast to previous studies involving the use of parasitic scatterer for decoupling antennas, we demonstrate using antenna impedances the underlying decoupling mechanism for two arbitrary antennas. By a proper choice of parameters, perfect matching and decoupling can be obtained for a given antenna spacing without extending the overall area used, and without introducing additional decoupling networks. The price to pay is a reduction of bandwidth relative to that of widely spaced antennas, which is the case for other decoupling methods as well. Simulation and experimental results are used to substantiate the effectiveness of the proposed design approach on a two-monopole array with an antenna spacing of 0.1 wavelength. Finally, several practical considerations of the proposal are also presented, including the extension of the approach for more than two active antennas and its implementation in mobile terminals.

A Compliant Parallel XY Micromotion Stage With Complete Kinematic Decoupling

Abstract: This paper presents a novel compliant parallel XY micromotion stage driven by piezoelectric actuators (PZT). With the purpose to obtain complete kinematic decoupling and good stiffness performance, the stage is designed using a symmetric 4-PP structure in which double four-bar flexure is chosen as the prismatic joint. Matrix method is employed to establish the compliance model of the mechanism. Based on the model, dynamic analysis is investigated after static analysis is carried out. The dimensions of the mechanism are optimized using the particle swarm optimization (PSO) algorithm in order to maximize the natural frequencies. Finite-element analysis (FEA) result indicates that the mechanism has an almost linear force-deflection relationship, high first natural frequency (720.52 Hz), and ideal decoupling property. To cope with the nonlinearities such as hysteresis that exists in the PZT, the control system is constructed by a proportional-integral-derivative (PID) feedback controller with a feedforward compensator based on Preisach model. The fabricated prototype has a 19.2 μm × 8.8 μm rectangular workspace with coupling less than 5%. The result of the closed-loop test shows that the XY stage can achieve positioning, tracking and contouring tasks with small errors.

A Three-port Flyback for PV Microinverter Applications With Power Pulsation Decoupling Capability

Abstract: A novel single-stage photovoltaic (PV) microinverter with power decoupling capability is proposed in this paper The proposed topology is based on three-port flyback with one port dedicated to power decoupling function so as to reduce the decoupling capacitance, thus allowing for long lifetime film capacitor to be used Operation principle is analyzed in details Key design considerations, including key parameter selections, predictive control strategy, and the dc voltage balance control across the power decoupling capacitor, are given in this paper A 100-W microinverter prototype is built to verify the proposed topology Experimental results show the proposed topology can achieve power decoupling, while maintaining good efficiency

Decoupling of ionic transport from segmental relaxation in polymer electrolytes.

Abstract: We present detailed studies of the relationship between ionic conductivity and segmental relaxation in polymer electrolytes. The analysis shows that the ionic conductivity can be decoupled from segmental dynamics and the strength of the decoupling correlates with the fragility but not with the glass transition temperature. These results call for a revision of the current picture of ionic transport in polymer electrolytes. We relate the observed decoupling phenomenon to frustration in packing of rigid polymers, where the loose local structure is also responsible for the increase in their fragility.

Method for assigning structure of 1,2,3-triazoles.

Abstract: 1,4-Disubstituted-1H-1,2,3-triazoles 1 can easily be distinguished from the isomeric 1,5-disubstituted-1H-1,2,3-triazoles 2 by simple one-dimensional 13C NMR spectroscopy using gated decoupling. The C5 signal of 1 appears at δ ∼120 ppm, while the C4 signal of 2 appears at δ ∼133 ppm. Computational studies also predict the upfield shift of C5 of 1 relative to C4 in 2.

Design and Development of a Flexure-Based Dual-Stage Nanopositioning System With Minimum Interference Behavior

Abstract: Dual-servo systems (DSSs) are highly desirable in micro-/nanomanipulation when high positioning accuracy, long stroke motion, and high servo bandwidth are required simultaneously. This paper presents the design and development of a new flexure-based dual-stage nanopositioning system. A coarse voice coil motor (VCM) and a fine piezoelectric stack actuator (PSA) are adopted to provide long stroke and quick response, respectively. A new decoupling design is carried out to minimize the interference behavior between the coarse and fine stages by taking into account actuation schemes as well as guiding mechanism implementations. Both analytical results and finite-element model (FEM) results show that the system is capable of over 10 mm traveling, while possessing a compact structure. To verify the decoupling property, a single-input-single-output (SISO) control scheme is realized on a prototype to demonstrate the performance of the DSS without considering the interference behavior. Experimental results not only confirm the superiority of the dual-servo stage over the standalone coarse stage but reveal the effectiveness of the proposed idea of decoupling design.

I/O virtualization

Abstract: Decoupling a logical device from its physical implementation offers many compelling advantages.

Novel Dual-Band Decoupling Network for Two-Element Closely Spaced Array Using Synthesized Microstrip Lines

Abstract: We investigate an innovative decoupling network for dual-band two-element closely spaced arrays in MIMO applications. The new architecture, combining the reactive element decoupling technique and the eigenmode feed network, provides dual-band decoupling with good radiation characteristics and power balance between the modes. The core block of the decoupling network is a dual-mode 180-degree hybrid coupler; it functions as a conventional coupler in one frequency band but can be equivalent to a pair of isolated direct-thru transmission lines in the other band. This unusual dual-mode coupler is realized by synthesized microstrip lines (cells), consisting of line inductors, parallel-plate capacitors, and series LC tanks. A set of design equations, providing a systematic synthesis procedure of the unit cells, is discussed. The scheme of the dual-band decoupling network is illustrated first, followed by the details of the building circuit blocks; the experimental results and discussion are given at the end of the paper.

Attitude Sensing and Dynamic Decoupling Based on Active Magnetic Bearing of MSDGCMG

Abstract: This paper explores the attitude-sensing function of the magnetically suspended double-gimbal control moment gyroscope (MSDGCMG), which can combine the attitude sensing and the attitude control into a single device to achieve a compact lightweight spacecraft design. In this implementation, the two-axis angular velocity of spacecraft is sensed from the control signals in the active-magnetic-bearing control system for a high-speed rotor. Both the current- and displacement-force terms are considered in the proposed scheme in order to achieve a good tracking performance of angular velocity estimation. Furthermore, a dynamic decoupling and static compensation procedure is designed to eliminate the cross-axis angular velocity couplings. The magnetic-force-related parameters which are crucial for the control torque calculations are also experimentally identified. The simulation and experimental results obtained from an originally developed MSDGCMG prototype are used to demonstrate the effectiveness of the presented implementations.

Decoupling control for spatial six-degree-of-freedom electro-hydraulic parallel robot

Abstract: This paper presents a decoupling controller equipped with cross-coupling pre-compensation for an electro-hydraulic parallel robot, in order to weaken system dynamic coupling effects usually ignored on the design of advanced controllers and improve system control performance. The mathematical model of the electro-hydraulic parallel robot is built using the Kane method and a hydromechanics approach, and the kinematical model is established with a closed-form solution and the Newton-Raphson method. The feedback linearization theory is applied to reduce coupling effects stemmed from system dynamics of the parallel robot via incorporating force-velocity control with cross-coupling pre-compensations. The control performance involving stability, accuracy, and robustness of the proposed controller for spatial 6-DOF parallel robot is analyzed in theory and experiment. The experimental results illustrate that the proposed controller can highly improve the control performance by weakening system dynamic coupling effects of the electro-hydraulic parallel robot, especially for trajectory tracking performance.

Towards a green economy

Abstract: 4th Biennial CSIR Conference: Real problems relevant solutions, CSIR, Pretoria, 9-10 October 2012

The Role of Decoupling Points in Value Chain Management

Abstract: All supply chains are not the same. A key factor that affects the design and management of a value chain is the position of the customer order decoupling point; some products are produced to order (e.g. configured to particular customer needs) while others are produced to stock (typically standard products). The customer order decoupling point (CODP) identifies the point in the material flow where the product is linked to a specific customer. This paper discusses the impact of having the decoupling point at different positions, and the distinguishing features for value chain operations upstream the decoupling point (i.e. towards the supplier) versus those downstream the decoupling point (i.e. towards the ultimate customer). Based on these differences, we explore the implication of the CODP on the modelling of value.

Flexible transceiver array for ultrahigh field human MR imaging.

Abstract: A flexible transceiver array, capable of multiple-purpose imaging applications in vivo at ultrahigh magnetic fields was designed, implemented and tested on a 7 T MR scanner. By alternately placing coil elements with primary and secondary harmonics, improved decoupling among coil elements was accomplished without requiring decoupling circuitry between resonant elements, which is commonly required in high frequency transceiver arrays in order to achieve sufficient element-isolation during RF excitation. This flexible array design is capable of maintaining the required decoupling among resonant elements in different array size and geometry, and is scalable in coil size and number of resonant elements (i.e. number of channels), yielding improved filling factors for various body parts with different geometry and size. To investigate design feasibility, flexibility, and array performance, a multi-channel, 16-element transceiver array was designed and constructed, and in vivo images of the human head, knee, and hand were acquired using a whole-body 7T MR system. 7T parallel imaging with GRAPPA performed using this flexible transceiver array was also presented.

A novel active power decoupling method for single-phase photovoltaic or energy storage applications

Abstract: Conventional single-phase inverters exhibit double line frequency power pulsating, which affects dc sources such as photovoltaic performance and battery lifetime. Bulky dc-link electrolytic capacitors are typically employed as transient energy buffer to decouple the pulsating ac power from constant dc power, but such passive components suffer from temperature and aging concerns. For high reliability and high power density, active power decoupling approach is preferred. This paper presents a novel active power decoupling method by using a six-switch single-phase inverter topology. A small film capacitor is used as pulsating energy buffer in ac side, which not only improves the reliability but also the efficiency. A novel vector PWM for this topology is also proposed to maximize the dc voltage utilization, and to achieve the independent controls of the inverter output power and power decoupling. The simulation results have verified the proposed power decoupling method.

Multi-Channel Microstrip Transceiver Arrays Using Harmonics for High Field MR Imaging in Humans

Abstract: Radio-frequency (RF) transceiver array design using primary and higher order harmonics for in vivo parallel magnetic resonance imaging imaging (MRI) and spectroscopic imaging is proposed. The improved electromagnetic decoupling performance, unique magnetic field distributions and high-frequency operation capabilities of higher-order harmonics of resonators would benefit transceiver arrays for parallel MRI, especially for ultrahigh field parallel MRI. To demonstrate this technique, microstrip transceiver arrays using first and second harmonic resonators were developed for human head parallel imaging at 7T. Phantom and human head images were acquired and evaluated using the GRAPPA reconstruction algorithm. The higher-order harmonic transceiver array design technique was also assessed numerically using FDTD simulation. Compared with regular primary-resonance transceiver designs, the proposed higher-order harmonic technique provided an improved g-factor and increased decoupling among resonant elements without using dedicated decoupling circuits, which would potentially lead to a better parallel imaging performance and ultimately faster and higher quality imaging. The proposed technique is particularly suitable for densely spaced transceiver array design where the increased mutual inductance among the elements becomes problematic. In addition, it also provides a simple approach to readily upgrade the channels of a conventional primary resonator microstrip array to a larger number for faster imaging.

The myth of decoupling

Abstract: The decoupling hypothesis is the idea that business cycles in emerging market economies have become more independent from business cycles in advanced economies in recent years. Decoupling essentially amounts to a structural break in the degree of business cycle interdependence between the two groups of economies, and it can be tested as such. We develop an innovative measure of business cycle interdependence based on the Euclidean distance, available at the annual frequency, which allows for a proper test for a structural break in a graphical setup. We also make use of a standard econometric test. Both approaches point to the same conclusion: there has been no decoupling in recent years. If anything, the degree of business cycle interdependence has become stronger.

A simplified power management strategy for a supercapacitor/battery Hybrid Energy Storage System using the Half-Controlled Converter

Abstract: Hybrid Energy Storage Systems (HESS), which is commonly used in Electric Vehicles (EV), is a combination of two energy storage devices. Supercapacitors (SC) due to their high charge/discharge rate, high power density, long lifetime in comparison to batteries, and capability of supporting high stress represent an optimal solution for HESS when combining with batteries. In such HESS configuration dc-dc converter is needed. Half-Controlled Converters (HCC) is an excellent solution due to their low cost and similar efficiency in comparison to the most used types of converters. In this paper, a strategy for power distribution between SC and battery, based on current control and a filter decoupling technique is proposed, along with the method to evaluate the decoupling frequency. The proposed strategy overtakes other approaches, such as fuzzy control or neural network, in terms of a faster and less complex implementation.

Decoupling circuits for filtering a voltage supply of multiple power amplifiers

Abstract: Embodiments for at least one method and apparatus of a voltage supply are disclosed. One voltage supply apparatus includes a voltage supply, a plurality of power amplifier (PA) decoupling circuits, and a plurality of power amplifiers. Each PA decoupling circuit is connected to the voltage supply and provides a filtered voltage supply to a corresponding one of the plurality power amplifiers. Each PA decoupling circuit configured to suppress noise of the provided filtered voltage supply below a threshold at one or more selected frequencies, wherein the suppression is provided by the PA decoupling circuit operating in conjunction with at least one other of the plurality of PA decoupling circuits.

A case study of side-channel analysis using decoupling capacitor power measurement with the OpenADC

Abstract: When capturing power measurements for processing with side-channel analysis, there are many options with regards to both how the measurement is taken, and also how that measurement is digitized. This work concentrates on a new technique which measures the current through a decoupling capacitor, with a probe that can easily be built in any electronics lab. In addition an open-source digitizer board is presented, which is specifically designed to measure the signals required for side-channel analysis. The techniques presented in this work facilitate sharing of repeatable measurement techniques: the measurement environment presented can easily be duplicated at a very low cost.

Multiple decoupling point paradigms in a global supply chain syndrome: a relational analysis

Abstract: A responsive and flexible supply chain in the global product value chain set-up links the manufacturer with various inter-company entities, such as suppliers, distributors, contract manufacturers and customers to deal with volatile demand. It is imperative and prudent to look at the overall product chain rather than focusing on any single supply chain entity. From a supply chain perspective, it is crucial that these individual entities are lean and agile (leagile) themselves, as well as the overall product value chain. As a result of the global nature of the product value chain, the concept of the decoupling point has undergone a paradigm shift. Through the literature review the authors establish three different types of decoupling point existing in product value chains, namely: (1) product structure decoupling point (PSDP), bill of materials decoupling; (2) supply structure decoupling point (SSDP), supply network decoupling; and (3) demand transfer decoupling point (DTDP), associated with information sha...

Flyback type miniature photovoltaic grid connected inverter with power decoupling circuit and control method thereof

Abstract: A purpose of the present invention is disclosing a flyback type miniature photovoltaic grid connected inverter with a power decoupling circuit and a control method thereof The inverter comprises a flyback converter and a power frequency polarity conversion circuit The flyback converter is provided with a power decoupling circuit, a decoupling capacitance voltage grade is higher than output voltage of a solar energy photovoltaic array, decoupling capacitance voltage is allowed to fluctuate in a large range, thus decoupling capacitance capacity is decreased, power decoupling can be realized by only using a non-electrolytic capacitor, using an electrolytic capacitor is avoided, a service life of the miniature photovoltaic grid connected inverter is prolonged, and reliability is raised Through the control method, not only is decoupling of miniature photovoltaic grid connected inverter output power and solar energy photovoltaic array output power realized, but also direct current voltage and current waveform outputted by the solar energy photovoltaic array can maintain smooth, a service life of the solar energy photovoltaic array is guaranteed, and realization of maximum power point tracking (MPPT) is facilitated