Non-iterative Design Research Articles

An Intuitive and Noniterative Design Methodology for CLLC Chargers Employing Simplified Operation Modes Model

This paper mainly focuses on the simplified operation modes (SOM) model and resonant parameter design for the CLLC charger. Based on the mathematical and detailed operation waveform assumptions, the voltage gain model expressions and the operation mode boundaries are calculated directly, providing the high efficiency and high reliability of the CLLC converter. The proposed SOM model is more accurate in depicting the voltage gain compared with the conventional fundamental harmonic approximation (FHA) model. Moreover, the SOM model is more intuitive and has less computational complexity than the complicated and unsolvable time-domain model. As for the parameter design process, the inductance ratio <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k$</tex-math></inline-formula> and characteristic impedance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Z_{0}$</tex-math></inline-formula> are selected instead of specific inductances and capacitances. Relying on the SOM model, a step-by-step parameter design methodology is studied, which avoids repetitive iterations and streamlines the procedure. The voltage gain range, efficiency, soft-switching operation, mode boundaries, and system stability are considered comprehensively and realized in this process. The simulations and experiments validate that the proposed SOM model is accurate, and the design methodology is straightforward through a 1-kW CLLC charger prototype with 97% peak efficiency.

Universal and Non-Iterative Design Method for In-Phase Radiation of Microstrip Traveling-Wave Series-Fed Antenna Arrays

Microstrip traveling-wave series-fed antenna arrays (MTSAAs) have been popularly developed for radar systems in the millimeter-waveband. Because the antennas are connected and fed in series in MTSAA, in-phase radiation of the antenna elements with properly tapered amplitude for achieving a broadside beam with a low sidelobe level (SLL) is challenging. Although the reported series-fed patch and comb-line arrays accomplished the goal, design equations for the optimum distances between antenna elements in the series-fed array do not guarantee in-phase radiation due to the mutual coupling in array structures. Therefore, optimization of the distances in the array using full-wave simulations is inevitable. In this article, we propose the first universal and non-iterative design equation that compensates for the phase offset generated in patch and comb-line MTSAAs and successfully found optimum distances for broadside beams with low SLLs without optimization. Finally, we fabricated both MTSAAs with ten elements operating at 76.5 GHz and demonstrated almost 13 dB boresight gain and low SLLs near −18 dB without a beam tilt.

Multi-loop PID controllers design with reduced loop interactions based on a frequency-domain direct synthesis method

A novel direct synthesis (DS) method for simultaneous and non-iterative design of multi-loop PID controllers for stable multivariable processes is presented in this article. We deal with the specifications of the desired closed-loop dynamics, which is a critical design decision in the DS method, for designing multi-loop controllers. Control loop interactions in multi-loop control systems are usually undesirable but unavoidable due to inter-channel interactions of multivariable processes. The main feature of the method is that the multi-loop control design aims at reducing the interactions among loops. The proposed DS method specifies the design target in terms of the frequency response of the desired closed-loop transfer function (CLTF) and synthesizes the controllers in the frequency domain. We develop an approach to effectively specify the desired closed-loop frequency response to achieve improved control performance by minimizing the sum of the magnitude of the interactive parts in the desired CLTF matrix. With the desired closed-loop frequency response and a process model, the frequency response of an ideal multi-loop controller is synthesized and then approximated to a PID controller. We provide simulation studies of three industrial benchmark processes and a nonlinear quadruple tank system to illustrate the design result and performance of the proposed method and make comparisons with several existing methods. Our results prove the effectiveness of the frequency-domain DS method. The proposed multi-loop PID controllers achieve reduced loop interactions and provide satisfactory overall performance.

A non-iterative design for aileron to rudder interconnect gain

AbstractAileron to Rudder Interconnect (ARI) gain is implemented on most fighter aircraft, primarily to reduce the side slip produced due to adverse yaw from pilot lateral control stick input and to improve the turn rate response. A systematic and non-iterative design procedure for ARI gain is proposed herein based on the evaluation of a transfer function magnitude at the aircraft roll mode frequency. The simplicity of the proposed method makes it useful for real-time flight control law reconfiguration in situations where the aileron control authority is diminished due to damage. This is demonstrated by a simulation example considering an aileron surface damage scenario.

Optimal Advance Angle for Aided Maximum-Speed-Node Design of Switched Reluctance Machines

In the design processes of Switched Reluctance (SR) Machines that operate in wide constant power speed ranges, the maximum power available at maximum speed must be evaluated for every machine candidate. This is critical to ensure compliance with the power requirement. Important parameters to include in the design routine are the duration of the energizing period and the advance of the turn-on instant, i.e., advance angle. The latter is highly related to the machine geometry and is usually evaluated through time-consuming finite-element-based iterative methods. In this article, a simple, yet novel analytical model is proposed to cater for the torque-maximising advance angle in a closed-form analytical expression, directly from the machine geometry. The goal is to provide a non-iterative design tool that speeds up the design process. Successful validations against finite element analyses and experimental results on an SR machine prototype are reported. The main outcome of this article is shown by the improvement in computation time, without any significant loss of accuracy.

Noniterative design of IIR multiple‐notch filters with improved passband magnitude response

SummaryA noniterative method for the all‐pass–based design of infinite impulse response multiple‐notch filters is proposed. This method ensures that specifications regarding positions of notch, left‐ and right‐hand cutoff frequencies, are exactly met, leading to a symmetric magnitude response about notch frequencies. Passband magnitude response can be improved by increasing the order of the corresponding all‐pass filter.

Design and fabrication of DOEs on multi- freeform surfaces via complex amplitude modulation.

A non-iterative design and precise fabrication method of diffractive optical elements (DOEs) on multiple freeform surfaces is proposed and investigated in this paper. Complex amplitude modulation (CAM) technology is applied to design complicated DOEs. The wave-front for desired DOEs fabrication is interfered with a plane wave and then be encoded to a pure phase hologram. Simulations for different DOEs (binary and gray scales) on freeform surfaces are performed and the relative errors are 0.56% and 0.78%, respectively. Since the reconstructed optical fields generated by spatial light modulator (SLM) can be recorded into light-sensitive materials (photopolymer), the DOEs fabrication is realized by optical exposure. The results show that the proposed method can design and fabricate DOEs on multi-freeform surfaces at one time with high quality. Since the CAM method ensures precise reconstruction without iterations, the fabrication is accurate as well as the design is fast. It is expected that the proposed method could be applied in the precise 3D optical fabrication and processing in the future.

Effective damping and frequencies of viscous damper braced structures considering the supports flexibility

This paper presents a study on the optimal sizing of damping braces of MDOF systems equipped with viscous dampers where, unlike well-established computer-based optimisation methods, the deformability of the elastic supports is integrated by means of a novel non-iterative design tool. Mainstream optimisation methods usually focus on sizing supplemental damping devices neglecting the damper supports’ flexibility and therefore their effect on the overall structural damping and frequencies of vibration. In this work, the damping braces are modelled by way of viscous-elastic assemblies using the Maxwell representation. The equations of motion are formulated in the state-space representation to facilitate the assessment of the viscous-elastic assemblies’ effects. The system solution presented in form of contour plots is then used as a prime tool to select the design parameters for both dampers and supporting braces, while preserving a desired level of added damping. In addition, it is shown how this approach also gives the engineer the flexibility of either fixing a damper size to then determine the required supporting brace stiffness or fixing the supporting brace stiffness to then determine the maximum achievable damping. A case study taken from the literature is presented to illustrate the advantages of the proposed approach.

LCL Filter Design Method for Grid-Connected PWM-VSC

In recent years, several LCL filter design methods for different converter topologies have been published, many of which use analytical expressions to calculate the ideal converter AC voltage harmonic spectrum. This paper presents the LCL filter design methodology but the focus is on presentation and validation of the non-iterative filter design method for a grid-connected three-phase two-level PWM-VSC. The developed method can be adapted for different converter topologies and PWM algorithms. Furthermore, as a starting point for the design procedure, only the range of PWM carrier frequencies is required instead of an exact value. System nonlinearities, usually omitted from analysis have a significant influence on VSC AC voltage harmonic spectrum. In order to achieve better accuracy of the proposed procedure, the system nonlinear model is incorporated into the method. Optimal filter parameters are determined using the novel cost function based on higher frequency losses of the filter. An example of LCL filter design for a 40 kVA grid-connected PWM-VSC has been presented. Obtained results have been used to construct the corresponding laboratory setup and measurements have been performed to verify the proposed method.

Signal and artificial noise beamforming for secure simultaneous wireless information and power transfer multiple‐input multiple‐output relaying systems

Simultaneous wireless information and power transfer (SWIPT) is a potential technique to solve the energy scarcity problem in wireless communication networks. Information transmission security is one of the key issues to be addressed in SWIPT. In this study, the authors consider guaranteeing the information transmission security of a multiple-input multiple-output non-regenerative relay system with SWIPT in the physical layer by designing source and relay beamforming to maximise the security rate of the system. The problem is to design the source signal and artificial noise (AN) beamforming and the relay forwarding beamforming jointly, which is highly non-convex. They first propose an alternating optimisation-based algorithm, which designs the beamforming matrices at the source and relay separately and alternately. Next, they propose a joint design algorithm which designs the source signal and AN beamforming and the relay beamforming together. Finally, they propose a non-iterative design algorithm with low complexity. The performances of the proposed design algorithms have been verified by computer simulations.

Non-iterative design method for flexible channels with bends

Flexible linings provide a means of stabilising roadside channels. These linings conform to potential changes in channel shape while maintaining overall lining integrity. The current design method of flexible linings is based on trial and error and typically involves three sets of iterations. The method becomes extremely complex when lining type and channel dimensions are to be modified to satisfy three design criteria: discharge, permissible shear stresses and side slope stability. This paper presents an optimisation model that directly provides the best channel lining subject to the design criteria. The proposed model can handle a large number of constraints, and provides the optimal solution in seconds using the Excel Solver software. The model is developed for riprap, cobble and gravel linings. The user needs to specify available stone sizes, and then the model selects the best size for channel straight and curved segments. The application of the model is illustrated using numerical examples, and sensitivity analysis is performed. The proposed model has been validated by comparing its results with those of the trial method. The proposed model provides efficiency and flexibility in the design of roadside channels, and should be a useful design tool of interest to practitioners and researchers.

Analysis of the Interleaved Isolated Boost Converter With Coupled Inductors

This paper analyzes the interleaved boost with coupled inductors (IBCI) converter, which is an isolated topology that is suitable for high step-up applications. Two main contributions are given: an exhaustive steady-state analysis and an accurate small-signal model. The former allows for deriving a closed-form noniterative design procedure for the power-stage active and passive components. In addition, it reveals an interesting equivalence with an apparently different converter, i.e., the single active bridge. Subsequently, the IBCI converter dynamic behavior is investigated, deriving a nonlinear average model that, under small-signal approximation, can be linearized around a given operating point and used for feedback controller design. A single photovoltaic module interface converter, rated for 300-W output power, is considered as a case study to validate the analysis outcome and the design procedure. Both are fully validated by measurements taken on the laboratory prototype.

High-Precision Parallel Graphic Equalizer

This paper proposes a high-precision graphic equalizer based on second-order parallel filters. Previous graphic equalizers suffer from interaction between adjacent band filters, especially at high gain values, which can lead to substantial errors in the magnitude response. The fixed-pole design of the proposed parallel graphic equalizer avoids this problem, since the parallel second-order filters are optimized jointly. When the number of pole frequencies is twice the number of command points of the graphic equalizer, the proposed non-iterative design matches the target curve with high precision. In the three example cases presented in this paper, the proposed parallel equalizer clearly outperforms other non-iterative graphic equalizer designs, and its maximum global error is as low as 0.00-0.75 dB when compared to the target curve. While the proposed design has superior accuracy, the number of operations in the filter structure is increased only by 23% when compared to the second-order Regalia-Mitra structure. The parallel structure also enables the utilization of parallel computing hardware, which can nowadays easily outperform the traditional serial processing. The proposed graphic equalizer can be widely used in audio signal processing applications.

Transceiver Design Based on Interference Alignment in MIMO Interfering Broadcast Channels

In this paper, we develop a non-iterative transceiver design based on interference alignment (IA) for MIMO interfering broadcast channels with arbitrary number of cells and users per cell. By aligning the interference from other cells efficiently, we show that the proposed transceiver design can achieve the degrees of freedom (DOF) of d per user, i.e. total DOF of equation, where C is the number of cells, K i is the number of users for the i-th cell, and d is the number of streams per user. We also investigate conditions for the antenna configuration in order to attain the total DOF of equation. From simulation results, we demonstrate that the proposed transceiver design can obtain higher DOF than the conventional scheme under equal antenna configuration.

증폭 및 전달 릴레이 기반 다중 사용자 피어투피어 통신 시스템에서 강인한 MMSE 필터 설계 방법

In this paper, we propose robust relay and destination filter design methods for the multi-user peer-to-peer amplify-and-forward relaying systems while taking imperfect channel knowledge into consideration. Specifically, the relay and destination filter sets are developed to minimize the sum mean-squared-error (MSE). We first present a robust joint optimum relay and destination filter calculation method with an iterative algorithm. Motivated by the need to reduce computational complexity of the iterative scheme, we then formulate a simplified sum MSE minimization problem using the relay filter decomposability, which lead to two robust sub-optimum non-iterative design methods. Finally, we propose robust modified destination filter design methods which require only local channel state information between relay node and a specific destination node. The analysis and simulation results verify that, compared with the optimum iterative method, the proposed non-iterative schemes suffer a marginal loss in performance while enjoying significantly improved implementation efficiencies. Also it is confirmed that the proposed robust filter design methods provide desired robustness in the presence of channel uncertainty.

A noniterative design procedure for supplemental brace–damper systems in single‐degree‐of‐freedom systems

SUMMARYIn this paper, a method for designing supplemental brace–damper systems in single‐degree‐of‐freedom (SDOF) structures is presented. We include the effects of the supporting brace stiffness in the dynamic response by using a viscoelastic Maxwell model. On the basis of the study of an SDOF under ground excitation, we propose a noniterative design procedure for simultaneously specifying both the damper and the brace while assuring a desired structural performance. It is shown that to increase the damper size beyond the value delivered by the proposed criteria will not provide any improvement but actually worsen the structural response. The design method presented here shows excellent agreement with the FEMA 273 design approach but offers solutions closer to optimality. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Combined Transceiver Optimization for Uplink Multiuser MIMO with Limited CSI

Joint precoder and decoder optimization is considered for uplink multiuser multiple-input multiple-output (MU-MIMO) systems with limited channel state information (CSI) at both the transmitters and receivers. Instead of counting on complex iterative-based algorithms, an efficient and noniterative QR-based linear transceiver pair design is employed. In addition, an equal power distribution (EPD) scheme is applied to adjust transmit power allocation of each mobile station (MS) between its symbols under the total transmit-power constraint. Simulations are conducted to provide a comparative evaluation of the proposed QR-EPD algorithm with other transceiver designs on the sum mean-squared error (SMSE) and the averaged bit-error-rate (BER) performance.

A Mathematical Principle and Application on Design of Planar Six-Bar Mechanism with unto Three-Ordered Intermission at Limit Position(s)

A non-iterative design method about high order intermittent mechanisms is presented. The mathematical principle is that a compound function produced by two basic functions, and then one to three order derivatives of the compound function are all zeroes when one order derivative of each basic function is zero at the same moment. The design method is that a combined mechanism is constructed by six bars; the displacement functions of the front four-bar and back four-bar mechanisms are separately built, let one order derivatives of two displacement functions separately be zero at the same moment, and then get geometrical relationships and solution on the intermittent mechanism. A design example shows that this method is simpler and transmission characteristics are better than optimization method.

Non-dimensional design charts for unbonded, post-tensioned, split precast concrete walls

The Precast Seismic Structural Systems (PRESSS) research proposed five different seismic structural systems made from precast concrete elements. These systems formed various parts of the structural framing in the PRESSS phase III building that was tested at the University of California at San Diego. Based on the PRESSS evaluation, one of the structural systems that has the potential to eliminate residual drift after an earthquake was the unbonded, post-tensioned, split precast concrete wall system. The PRESSS report outlines a dimensional design procedure for the unbonded post-tensioned split precast concrete walls. This procedure is iterative, requiring lengthy calculations to achieve an optimum design. This study developed a set of new nondimensional parameters and procedures for the design of such walls. The goal of this research was to develop a set of nondimensional design charts that require no iterations. Such charts are based on an optimum design of zero residual drift while the moment capacity of the wall is equal to the applied design moment. The results of these studies were used to generate nondimensional design charts. A numerical design example using the conventional iterative PRESSS design procedure and the new noniterative design charts procedure is presented, and the methods are compared.

Design and fabrication of polarization-holographic elements for laser beam shaping

We report on an experimental realization of polarization-holographic optical elements (PHOEs) for laser beam shaping. The PHOEs were written into an azobenzene polymer layer by illumination with linearly polarized, focused light with spatially varying orientation. We propose a noniterative design method for the calculation of PHOEs that transform laser beams into arbitrary rotationally symmetric or separable intensity distributions such as flattop or ring profiles. The experimentally observed intensity distributions are compared with those predicted by numerical simulations based on the Fresnel diffraction approximation. Diffraction efficiencies up to 79% were determined experimentally.