Proposed Design Methodology Research Articles

Mode-dependent delays for dissipative filtering of stochastic semi-Markovian jump for neural networks

This work is concerned with the issue of dissipative filtering for stochastic semi-Markovian jump via neural networks where the time-varying delay is based upon another semi-Markov process. Dissipative performance analysis is employed to solve a mode-dependent filtering problem in a unified way. To achieve this task, we implemented the recently proposed notion of extended dissipativity, which gives an inequality equivalent to the well-known H_{infty }, L_{2}–L_{infty }, and dissipative performances. Different from the existing literature (Arslan et al. in Neural Netw 91:11–21, 2017; Chen et al. in ISA Trans. 101:170–176, 2020) where mostly delay-free filters have been investigated, our filter contains a communication delay. Based upon the delay-dependent conditions, for the analysis of stochastic stability and extended dissipativity for neural networks with time-varying delays, our results are obtained by using a mode-dependent Lyapunov–Krasovskii functional together with a novel integral inequality. Original stochastic filtering conditions are characterized by linear matrix inequalities. A numerical simulation is elaborated to elucidate the feasibility of the proposed design methodology.

Optimal design of a tunable electromagnetic shunt damper for dynamic vibration absorber

Dynamic vibration absorber (DVA) is an effective device for suppressing resonant vibration of noisy machineries and structures. However, the optimum design of DVA requires precise tuning of the damping force in the DVA, which unfortunately is often not practical and prone to changes of working conditions. In this paper, a tunable electromagnetic shunt damper (EMSD) with different opposing magnet pairs configurations is tested for the optimum design of DVA. The optimum magnet pairs configuration is derived to provide the maximum damping force in the DVA. Both simulations and experiments are conducted to verify the damping coefficient variation with the number of magnet pairs in the EMSD. The experimental optimization procedure of the DVA is designed according to the fixed-points theory. The damping force generated by the EMSD can be readily adjusted by varying the external resistance of the EMSD. This is the first experimental implementation report of the optimization procedure described in the fixed-points theory. The proposed tunable EMSD can conveniently allow for onsite optimal tuning of DVA. The proposed design methodology provides fine tuning of the damping coefficient of EMSD to achieve robust optimal DVA performance, even when subject to changes of external parasitic damping.

System Optimization: High-Frequency Buck Converter With 3-D In-Package Air-Core Inductor

In this work, we present the analytical model of buck converter with 3D in-package air-core inductor (150 μm thick). To optimize the power efficiency at a targeted power density, models including 3D inductor and power switches are developed. Compared to 3D EM simulation, the proposed inductor model has a modeling error within 12% for the inductance calculation. With the proposed design methodology, an inductor with Q-factor up to 35 @ 300 MHz is achieved. From the system aspect, the loss breakdown in the integrated power converter is investigated. A 0.5-ratio buck converter can reach 88.5% efficiency @ 1–5W/mm2 based on the optimized inductor designs, with output voltage ranging from 0.7 V to 0.9 V and based on 28 nm CMOS.

Design Methodology Based on Dual Control of a Resonant Dual Active Bridge Converter for Electric Vehicle Battery Charging

In this paper, a detailed design methodology of a Resonant Dual Active Bridge (R-DAB) converter is proposed for battery charging applications. The converter design methodology is tailored to the charging profile of a Li-ion battery and is based on unique operating points (UOPs) that derive from a dual control method analysis. Specifically, both Pulse Frequency Modulation (PFM) and Phase-Shift Modulation (PSM) are adopted, to minimize the switching losses and the reactive power at the resonant tank. A detailed flowchart is presented, considering multiple design parameters and the UOPs, so that the resonant tank parameters are not overestimated. Simulation results of a conventional charger are presented, that validate the control method and design procedure. Finally, a 1kW|30A laboratory prototype charger is designed and evaluated, using a closed loop control system. The analysis of the experimental results proves the significance of the dual control method and verifies the proposed design methodology.

Seismic Performance of a New Type of Coupled Shear Wall with Replaceable Components: Experimental Validation

ABSTRACT This study proposes a new type of reinforced concrete (RC) coupled shear wall with replaceable coupling beams and replaceable corner components (RCCs) installed at the bottom corners of wall piers. To assess the seismic performance of the new coupled shear wall and verify the proposed design methodology, four 1/2-scale specimens including one conventional RC coupled shear wall and three new coupled shear walls were tested under lateral cyclic loading. The test results indicate that compared with conventional RC coupled shear walls the seismic performance of the new coupled shear wall is significantly improved.

Tuning of state-feedback multi-resonant controllers based on LQR using differential evolution metaheuristic

This paper proposes a generic methodology for tuning state-feedback multi-resonant (SF-MR) controllers in power electronics applications involving L, LC, and LCL filters. The tuning of the controllers is performed using differential evolution metaheuristic in conjunction with the well-known linear-quadratic regulator (LQR) approach. This optimization algorithm avoids the empirical trial-and-error method for adjusting the weighting values of Q and R matrices while minimizing the cost function based on a weighted sum of the total harmonic distortion of the controlled variables, control loop errors, and control signals saturation. Thus, an adequate approach to adjust LQR-SF-MR controllers is achieved, proving useful for controlling active power filters (APF) since non-sinusoidal control references are involved. Furthermore, the proposed tuning method is appropriate for controlling voltage source inverters (VSI) following sinusoidal references and feeding non-linear loads since the high rejection of harmonic disturbances is reached. The effectiveness of the proposed design methodology for controllers' tuning is tested in a current-controlled 3-phase 4-wire (3P4W) shunt-APF, grid-connected through both L and LCL filters, as well as in a voltage-controlled 3P4W VSI connected to non-linear loads with LC filters. The control performances of the systems are extensively evaluated through experimental results.

Design of steel wire loop connection for precast reinforced concrete structural components

Loop connection for precast RC structural components using U-bars is advocated by researchers on the grounds of simple mechanism and strength. However, the system is difficult to materialize on-site, in the lieu of which U-bars may be replaced with steel wire ropes, which offer a more suitable system with regards to convenience during the installation process. However, literature lacks on design requirements and methodology for loop connection. Thus, a theoretical study was undertaken to formulate the design methodology for loop connection formed using steel wire ropes. The behaviour of loop connection is governed by tension and shear, influenced by characteristics of wire ropes, grout and vertical transverse bar. A design example is illustrated for loop connection between precast wall-column, whose validation is demonstrated through numerical analysis and performance compared with monolithic system and U-bar connection. The advantages of the research relates to the systematic design approach considering all the influencing parameters of steel wire loop connection for precast components. It is expected that the proposed design methodology will be useful to practising engineers for designing the loop connection for precast components.

Terahertz beamforming network with a nonuniform contour.

This paper presents a terahertz beamforming network based on a nonlocal lens with a 2D beam-scanning demonstration through leaky-wave antennas. The proposed design methodology is novel, to the best of our knowledge, in the aspect of using unconventional optimization parameters to significantly reduce the phase error associated with this class of beamformers. In this approach, a nonuniform contour defined by Fourier series expansion is used as a new optimization parameter to significantly decrease the phase error over a larger scan-angle than that in the previous works. The proposed system is a good candidate for industrial and security applications such as automotive radar sensors and electromagnetic THz imaging, thanks to its extensive 2D scanning range: -68∘ to 0° in the elevation plane and -45∘ to +45∘ in the azimuth plane over the frequency range of 140-180 GHz.

Effect of Flexibly Attached Secondary Systems on Dynamic Behavior of Light Structures

This paper investigates the effect of flexibly attached secondary systems (FSS) on the dynamic behavior of primary structures (PS) under harmonic and seismic ground excitations. An FSS affects the main structure during ground excitation differently than a secondary system that is rigidly attached to it. Small displacements in the FSS are used to derive the equations of motion that define the behavior of the PS and FSS. The analytical formulation presented is validated by a finite element (FE) study conducted in SAP2000. The influence of mass ratio, tuning frequency ratio, and excitation frequency ratio on the dynamic behavior of the PS is investigated. The results show that the combined system (PS+FSS) behaves as a modified single degree of freedom (SDOF) structure at higher tuning frequency ratios. The dynamic response of the structure is independent of the mass ratio at low tuning frequency ratio of FSS. Under seismic excitations, the flexible structure’s response reduces considerably as the mass ratio increases, compared to a stiff structure at a higher tuning frequency ratio. When the tuning frequency ratio is equal to one, smaller mass ratios of FSS increase the seismic performance of the stiff structure. A design methodology is proposed to measure the spectral acceleration of the primary structure by incorporating the effect of FSS in the design response spectrum. An analysis of the tuning frequency ratio and mass ratio on the modified design spectrum is also presented. Finally, the proposed design methodology is validated with an existing study.

Concrete-filled and bare 6082-T6 aluminium alloy tubes under in-plane bending: Experiments, finite element analysis and design recommendations

The application of aluminium alloys in structural engineering is growing owing to their high strength-to-weight ratio, aesthetic appearance and excellent resistance to corrosion. However, the low modulus of elasticity of aluminium poses adverse effects on the flexural response of structural members made of aluminium alloys. In case of tubular members, the performance can be improved with the addition of concrete infill. Research on the flexural response of concrete-filled aluminium alloy tubes is still minimal. This study presents experimental and numerical investigations on the behaviour of concrete-filled and bare 6082-T6 aluminium alloy tubular members under in-plane bending. In total 20 beams, including 10 concrete-filled aluminium alloy tubular (CFAT) and 10 bare aluminium alloy tubular (BAT) specimens, were tested. The specimens comprised of square and rectangular hollow sections and were filled with 25 MPa nominal cylinder compressive strength concrete. The experimental results are reported in terms of failure mode, flexural strength, flexural stiffness, ductility and bending moment versus mid-span deflection curve. Compared to the BAT specimens, the counterpart CFAT specimens have shown remarkably improved flexural strength, stiffness and ductility due to the concrete infill and the improvement is more pronounced for the specimens with thinner sections. Finite element models of BAT and CFAT beams were developed by taking into account the nonlinearities in geometry and material and validated against the experimental data. A parametric study considering a broad range of cross-sections and different concrete grades was conducted based on the validated models. The FE results have shown that the flexural strength of the BAT and CFAT members increases with the increase of cross-sectional aspect ratio, wall thickness and concrete grade. The results obtained from experiments and numerical analysis for BAT members were used to assess the flexural capacity predictions and the applicability of the slenderness limits provided in the European standards. It was demonstrated that the slenderness limits provided by Eurocode 9 are conservative for Class A aluminium sections. Hence, revised Class 1, Class 2 and Class 3 limits are proposed which appear to be better applicable to Class A aluminium alloys. In the absence of design specifications for CFAT flexural members, the design rules for concrete-filled steel tubular flexural members provided by Eurocode 4 were adopted and the material properties of steel were replaced with those of aluminium alloy. It was shown that the proposed design methodology is suitable for the design of CFAT flexural members. Moreover, a slenderness limit for compact sections of CFAT flexural members is proposed based on Eurocode 4 framework.

Design Methodology of Free-Positioning Nonoverlapping Wireless Charging for Consumer Electronics Based on Antiparallel Windings

Free positioning wireless charging for consumer electronics allows the devices to be charged at arbitrary positions and angles to improve user experience. However, a user-initiated sudden movement of the device during charging can cause hazards due to the abrupt variation of the coupling coefficient. To solve this issue, the coupling coefficient variation at different positions should be mitigated, which is also good for the design and high-efficiency operation of power electronics converters. This article proposes a design methodology to employ antiparallel windings to smooth the coupling coefficient variation over different positions by reducing the coupling coefficient at central positions and enhancing it at boundary positions. Two optimization methods are proposed: turn-by-turn optimization and winding-by-winding optimization. A design flow is offered. The hexagonal coil is compared with the square coil and proved to achieve better performance than the latter. An experimental prototype is implemented to validate the effectiveness of the proposed design methodology.

Topology optimization to maximize eigenfrequencies of multi-material structures

A multi-material structure that is composed of several different material properties is promising for achieving an ideal functionality that can outperform a single material structure. In particular, increasing the value of the fundamental eigenfrequency is important because it can increase dynamic stability. Since the beginning, Topology optimization (TO) to maximize the fundamental eigenfrequency of a single-material structure has been investigated. However, there are few research papers on multi-material topology optimization (MMTO) for the eigenfrequency maximization problem thus far. Therefore, we propose a novel framework for the MMTO of the eigenfrequency problem. From a theoretical standpoint, two key features are addressed: (i) multi-material level set (MMLS) method is developed. In this method, interfaces between different material phases are represented by iso-surfaces of multiple level set functions. Hence, the optimal solutions have a 1/0 binary structure and are free from greyscale elements; (ii) The proposed design methodology uses a reaction-diffusion equation (RDE) to update the level-set functions based on the topological derivative, allowing new holes to form during the optimization process. The effectiveness of our methodology is demonstrated by benchmark test cases.

固有振動問題を対象としたマルチマテリアルトポロジー最適化

Multi-material structures consisting of several different material properties are promising for achieving ideal functionality over single-material structures. In particular, increasing the value of the fundamental eigenfrequency is important because it can enhance dynamic stability. Since the beginning, topology optimization (TO) for maximization of the fundamental eigenfrequencies of single-material structures has been studied. However, there have been few research papers on multi-material topology optimization (MMTO) for eigenfrequency maximization problems. Therefore, we propose a new framework for MMTO of eigenfrequency problems. In the proposed method, a multi-material level set (MMLS) method is developed, which represents the interfaces between different material phases by isosurfaces of multiple level set functions. The proposed design methodology uses the reaction-diffusion equation (RDE) to update the level set functions based on topological derivatives, allowing the nucleation of new holes during the optimization process. In addition, the eigenfrequency analysis with ersatz material and that without ersatz material using body-fitted mesh are compared and discussed.

Orbit Design for a Satellite Swarm-Based Motion Induced Synthetic Aperture Radiometer (MISAR) in Low-Earth Orbit for Earth Observation Applications

Soil Moisture and Ocean Salinity mapping by Earth observation satellites has contributed significantly toward a better understanding of the Earth system, such as its hydrosphere or climate. Nevertheless, an increased spatial resolution below 10 km with a radiometric resolution in the range of 2 K–3 K of radiometric data could yield a more complete picture of global hydrological processes and climate change. Operational radiometers, such as SMOS, have already approached prohibitive sizes for spacecraft due to the required large antenna apertures. Therefore, radiometer concepts based on a large number of satellites flying in close proximity (swarms) have been proposed as a possible solution. This article investigates the orbit mechanics of placing a satellite swarm-based motion induced synthetic aperture radiometer (MISAR) in low Earth orbit for Earth observation applications. The aperture synthesis antenna array is formed by a large number of individual antennas on autonomously controlled nanosatellites (deputies) and a correlator antenna in the Y-configuration carried by a chief satellite. The proposed design methodology is based on the optimization of satellite positions within a plane and the subsequent translation of coordinates into initial conditions for general circular orbits (GCOs). This enables a more computationally efficient orbit optimization and ensures the time invariance of the antenna array response. Based on this methodology, simulations have been performed with swarms consisting of up to 96 satellites. Simulations show that the spatial resolution of an aperture synthesis radiometer can be increased to less than 10 km for applications where the requirements on radiometric sensitivity are more relaxed ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta T\sim 3$ </tex-math></inline-formula> K).

Regional T-S Model-based Attitude Tracking Control of a Quadrotor with Input Saturation and External Disturbances

This paper presents a model reference attitude tracking controller design for a quadrotor unmanned aerial vehicle subject to saturated actuators and external disturbances. The dynamical nonlinear model of the quadrotor's attitude is represented by an uncertain-like Takagi-Sugeno model, with exact matching on a compact subset of the state space. The generalized sector condition is employed to deal with the saturated inputs of the quadrotor. LMI conditions are derived for the design of the proposed tracking controller from a quadratic Lyapunov function, together with a performance index used to minimize the L2-norm transfer between the disturbances and the state tracking errors. Because of the input saturation and the validity domain of the Takagi-Sugeno model, the obtained results only hold regionally and an optimization procedure to estimate the closed-loop tracking domain of attraction is proposed. Simulation results are provided to illustrate the effectiveness of the proposed design methodology.

A Novel Design Methodology for a Multioctave GaN-HEMT Power Amplifier Using Clustering Guided Bayesian Optimization

The increasing demand of high-performance power amplifiers (PAs) for modern wireless systems has led the PA structures becoming more complex, thereby resulting in an extremely difficult optimization process for PA design. In this paper, the Bayesian optimization (BO) algorithm with a novel acquisition function, namely clustering guided Gaussian process upper confidence bound (CG-GPUCB) method, is proposed for the optimization of a multi-octave PA. To validate the developed optimization strategy, a high-performance multi-octave PA with a 10-W gallium nitride (GaN) transistor has been successfully implemented. The measured performance of the fabricated PA over the frequency band between 0.6 GHz and 2.8 GHz show that the output power is greater than 40 dBm, the power added efficiency (PAE) is over 62%, and the gain is more than 10 dB. Compared with existing BO based method, the proposed methodology is more efficient, since this method can allow achieving better performance for PAs with less optimization time. A comparison between the achieved results and the performance of other state-of-the-art PAs based on different optimization algorithms has highlighted the validity of the proposed design methodology and the obtained improvement in terms of bandwidth.

Practical Papers, Articles and Application Notes

RF receivers for airborne applications are critical systems for wireless signal reception and processing. Any unwanted interfering signals received by the receiver have a direct impact on the quality of the intended signals. The first paper, “Improved Complex Receiver System Design Strategies to Overcome EMI/EMC Challenges,” describes the strategies and implementation techniques for a complex receiver system design to meet environmental stress screening (ESS) requirements, especially EMC. The proposed design methodology segregates the various modules and stacks them together tactfully without compromising EMC. By applying these techniques, an actual design with four modules is demonstrated and tested for EMC compliance over an extreme temperature range from -40°C to +71°C.

Compact Multilayered Balanced-to-Balanced Dual- and Tri-Band Diplexers Based on Magnetically Coupled Open-Loop Resonators

Two new compact balanced-to-balanced diplexers composed of two multiband balanced bandpass filters in a multilayer configuration are proposed in this letter to perform dual- and tri-band responses. The balanced bandpass filters are based on the use of magnetically coupled open-loop resonators. The magnetic coupling results in a strong inherent common-mode rejection, greater than 40 dB within all the dual-band diplexer passbands and greater than 30 dB for the tri-band diplexer passbands. All passbands in both diplexers are close to each other and well separated thanks to the presence of several transmission zeroes between them. Operating frequencies have been selected to be within the L band, used for many applications such as mobile services or satellite navigation. Specifically, the dual-band diplexer passbands are located at 1.08/1.58 GHz and 1.3/1.8 GHz with fractional bandwidths of 7/5.2 % and 7.4/5.5 %, while the tri-band diplexer passbands are located at 1.7/2.2/2.79 GHz and 1.97/2.37/2.95 GHz with fractional bandwidths of 4.1/4.6/3.5 % and 5.6/4.6/3.7 %. Measurements of two different prototypes are provided to validate the obtained simulation results, illustrating in this manner the usefulness of the proposed design methodology.

Optimized Parameter Design of the Dual-Loop Control for Grid-Forming VSCs WithLCFilters

This article provides a simple methodology to achieve an optimized parameter design of the dual-loop control for grid-forming voltage source converters (VSCs) with <i>LC</i> filters. The optimized parameter design is conducted for the current inner loop and voltage outer loop independently without any coupling, and the design processes of these two loops are exactly the same. Moreover, in the proposed design, standard analysis and design tools, e.g., pole map and Bode-plot can be directly employed while complex formula solving is needless. Therefore, this methodology is easy to implement for a practical engineering. In addition, contrary to common sense, it has been identified that the proportional controller in the outer loop has a negligible impact on the control bandwidth of typical medium power rating VSCs and thus can be eliminated to further simplify the design process and control structure. The left resonant controller can then be refined to achieve a significantly improved dynamic performance of the output voltage of VSCs. Detailed processes and considerations of the proposed design methodology are introduced and analyzed. Its effectiveness and performance are carefully verified by experimental results from a single-phase scaled-down VSC prototype.

A Youla–Kucera formulation of the controller design from data problem

The Youla–Kucera parametrization is a fundamental result in system theory, very useful when designing model-based controllers. In this paper, this formulation is employed to solve the controller design from data problem, without requiring a process model. It is shown that, given a set of input–output data generated by the plant and a desired closed-loop reference model, it is possible to estimate an stable filter that parametrizes the controller that minimizes the norm between the closed-loop dynamics and the requested behavior. The employed parametrization gives more degrees of freedom in the controller design than previous works in literature, allowing to achieve more stringent closed-loop performances. The proposed design methodology does not imply a plant identification step and it provides an estimate of the model-matching error between the requested and the resulting model as indicator of stability and performance of the derived control loop. The proposed solution is evaluated in regulation problems for non-minimum phase systems through Monte Carlo simulations and in experimental conditions for the regulation of temperature in an ohmic assisted hydrodistillation process.