Proposed Design Method Research Articles

Optimum Design of Multi-Section Asymmetrical Transdirectional Couplers with Port Impedance Matching up to S Band Frequency

The method of least squares is developed for the optimum design of multi-section asymmetrical transdirectional (ATRD) couplers with arbitrary port impedance matching. Firstly, transmission matrix of a section of coupler is obtained, then the transmission matrix of whole multi-section coupler is determined, from which the scattering matrix of device is obtained. An error function is then constructed by scattering parameters. According to design specifications, error function depends on physical parameters of coupler (such as widths, spacings and lengths of transmission line sections and capacitor values), of which minimum point gives optimum values of it’s dimensions and capacitors. Optimum design is carried out for a specified frequency response and bandwidth. Error minimization is implemented by the combination of genetic algorithm (GA) and conjugate gradient method (CGM). The design is verified by full-wave simulation software, fabrication and measurement. Several 3 dB, 6 dB and 10 dB couplers are designed with different bandwidths and port impedances. Compared to the proposed design method, design of asymmetrical multi-section couplers by full-wave simulation softwares is by trial and error and at best random and almost impossible because of extremely high CPU time due to the large number of parameters of coupler geometrical structure.

Asynchronous Extended Dissipative Filtering for T–S Fuzzy Markov Jump Systems

This article is concerned with the asynchronous reliable extended dissipative filtering problem for a class of continuous-time T–S fuzzy Markov jump systems. The modes of the encountered sensor failures and the designed filter are considered to be asynchronous with the original systems, which can be described by two mutually independent hidden Markov processes. By proposing double variables-based decoupling principle and variable substitution principle, a new condition is presented to guarantee the filtering error system to be stochastically stable and extended dissipative. Compared with the existing works, the proposed method does not impose constraints on Lyapunov variables and slack variables, and some unnecessary constraints on the system structure are removed. These directly lead to less conservative and more general results. An example is provided to illustrate the effectiveness of the proposed design method.

Partition Layout Loading of Frequency Selective Surface Absorbers on the Curved Surfaces for the Significant RCS Reduction

In this article, the significant radar cross section (RCS) reduction of curved surfaces in the low microwave frequency band is reported. The design method of partition layout loading of frequency selective surface (FSS) absorbers to control the surface current is put forward. Comparison of the scattering field intensities of different zones on the curved surface clearly shows that surface current should be suppressed in a large zone to effectively reduce the RCS of the curved surface at these frequencies. FSS absorbers under normal and 45° angle of incidence are designed and placed on the different zones of the curved surface to realize the partition layout loading, and remarkable RCS reduction has been obtained. Specifically, more than 15-dB RCS reduction is achieved in 1.05–1.45 GHz, and absorption above 90% is obtained from 0.95 to 1.5 GHz for TE polarization. The great agreement between the simulated and measured results validates the proposed design method.

2 n -Way Wideband Filtering Power Dividers With Good Isolation Enhanced by a Modified Isolation Network

In this article, a class of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{n}$ </tex-math></inline-formula> -way wideband filtering power dividers (FPDs) is presented and designed with a wide isolation band. It consists of ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{n}-1$ </tex-math></inline-formula> ) two-way power-dividing units and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> three-line coupled lines. The basic two-way power divider is achieved by replacing a simple isolation resistor of the conventional Wilkinson power divider with a modified isolation network, so as to improve the bandwidth of better-than-20-dB isolation band from 40% to 120%. The modified isolation network is composed of one quarter-wavelength coupled line, two quarter-wavelength transmission lines, and one resistor. The three-line coupled line is introduced at each output of the proposed FPD to improve its frequency selectivity and passband bandwidth. Furthermore, after placing one additional isolation resistor on each three-line coupled line, the number of output ports in the proposed power divider could be doubled without introducing more two-way power-dividing units. Finally, a prototype two-way and two prototype four-way wideband FPDs with different occupied sizes are designed and fabricated. The feasibility of the proposed design method is verified by the good agreement between the simulated and measured results.

Proposed Design Methods for Timber Members Subjected to Blast Loads

Proposed Design Methods for Timber Members Subjected to Blast Loads

인공지능 머신러닝을 이용한 카트-펜듈럼 이동제어 시스템 성형입력 설계

The tower crane is widely used in construction and transportation engineering. To improve working efficiency and safety, input shaping methods have been applied. Input shaping is a method of reducing residual vibration of flexible systems by convolving a sequence of impulses with unit step command. However, input shaping is based on the linear system theory in which its control performances are degraded, in case of nonlinearity and unmatched dynamics of the control systems. In this paper, a new optimal reference input shape design method based on minimizing cost function is suggested and applied, to a simple cart-pendulum system which is a simplified model of tower cranes. Since pendulum dynamics is nonlinear, analytic solution does not exist. To overcome this problem, in this paper, a machine learning approach is suggested to find optimal reference input shape for the cart position control. The feasibility of the proposed design method is verified through some simulation examples by using MatLab.

A Semantic Ontology-Based Approach to Support Model-Based Systems Engineering Design for an Aircraft Prognostic Health Management System

The Prognostic and Health Management (PHM) system of an aircraft has complex structures and diverse functions. It is highly coupled with other systems, such as the avionics system and flight management system. The Model-based Systems Engineering (MBSE) method is effective to support the design and verification of the aircraft PHM system. As a powerful semantic web construction method, ontology has been widely used to express design information, such as the concepts and the relationships between them. However, traditional graphical MBSE models have a natural weakness in transforming into ontology. In this paper, a semantic MBSE method is proposed to support the transform of the ontology model. Firstly, according to the design characteristics of the aircraft PHM system, a meta-model library of the aircraft PHM system is developed to support the design and evaluation. An MBSE modeling method based on requirement analysis, function analysis, logical architecture design, and physic architecture design is applied in the PHM design process. Secondly, the semantic system modeling language KARMA based on “graph, object, property, point, relationship, role, and extension” (GOPPRRE) is used to transfer the graphical MBSE model to the semantic MBSE model, which can be easily transformed to an ontology model. Finally, an ontology based on semantic modeling is developed to describe the MBSE entities and to support MBSE design. In this paper, a case study of an aircraft fuel PHM system is carried out to validate the proposed method. Based on the developed meta-model library, a complete MBSE design process for the aircraft PHM system is realized. And then an ontology model supporting PHM system design is generated from the semantic MBSE model. The MBSE ontology provides a shareable capability to help designers communicate effectively. Quantitative analysis based on ontology is also provided to verify the complexity and scale of the MBSE design process. Moreover, logical reasoning ability can also be provided to support the early requirement traceability for MBSE design. In general, the case study results show the feasibility and effectiveness of the proposed method for the aircraft PHM system design.

Culture coding - a method for diversifying artefact associations in design ideation

ABSTRACT It can be claimed that technological systems are, in some ways, reflections of the designers’ way of thinking. These designs affect the behavior of the users and contribute to the reproduction of future designs, thus strengthening the existing human-technology relations. To address these issues critically, there is a need to challenge design ideation processes for generating a larger variety of design proposals that can contribute to varied users and user behavior. For this purpose, we propose a new method- Culture Coding, that can complement design ideation processes where generating, developing, and elaborating ideas is crucial. In this qualitative study, we explore the value of the proposed method in design by using design activities and a research-through-design approach. The experimental setup consists of two Design Cases where study participants contributed by taking part in two co-design workshops. The findings of the study indicate that Culture Coding may help to guide attention to new perspectives and challenge assumptions of the design context.

Optimal Design of Subway Train Cross-Line Operation Scheme Based on Passenger Smart Card Data

The network operation of the subway can reduce the number of passenger transfers and improve subway operation efficiency. Based on the subway smart card data, this paper proposes an optimal design method for the cross-line operation scheme of subway trains. The method firstly calculates the OD matrix between subway stations, the passenger section flow, and the transfer flow according to the passenger smart card data. It then optimizes the design of the subway train cross-line operation plan, including determining the routing type of cross-line operation and the number of trains running. Finally, for the lines with cross-line operation conditions in the urban subway system, we design the cross-line operation schemes under all possible combinations. According to the volume of the cross-line passenger flow that the cross-line trains can carry, the top-ranked operation plans are preferably recommended. Taking the Chengdu subway network as an example, the research results show that, in the Chengdu subway network, the North Railway Station, Xibo City Station, and South Railway Station bear the highest transfer demand. The transfer demands that can be undertaken by cross-line trains are 23,934, 16,710, and 13,024 trips per hour, respectively. This shows that the proposed design method can accurately and reasonably screen out the transfer stations and lines with an urgent need for cross-line trains.

A design method for a novel movable tooth drive with logarithmic spiral conjugated tooth profiles

This paper presents a method for designing a novel type of movable tooth drive characterized by logarithmic spiral conjugated tooth profiles, which are in almost full surface contact owing to such innovative tooth geometry, in comparison with the conventional involute or cycloidal tooth profiles creating a linear contact. Firstly, the existence conditions of the conjugated curve of the logarithmic spiral are researched by establishing the meshing equation, and its geometric and kinematic properties are identified to design the conjugated tooth profiles of the movable tooth and ring gear. Then, wave generator profile, according to the requirement that it should be completely convex and smooth, is designed and modified to ensure the consistency with load capacity of the conjugated tooth profiles. On this basis, dimensional synthesis of the mechanism is performed following the influence analysis of main factors on the force/motion transmission characteristic of the whole machine. Finally, the virtual prototype is developed and the proposed design method is validated by relevant force performance simulation. The outcomes lay a significant foundation for the design of such logarithmic spiral tooth profile transmission.

Lens design for parallel cylindrical anamorphic attachments with finite object distance.

A lens design method for parallel cylindrical anamorphic attachments with finite object distance is provided, which includes paraxial lens design, thin lens design, and thick lens design. The paraxial lens data can be determined from geometric optics. The thin lens design adopts a total of 28 anamorphic aberrations. The anamorphic lens splitting method for each anamorphic lens module is also provided for anamorphic aberration balancing between anamorphic lens modules. With the proposed design method, an anamorphic attachment is designed and manufactured in this paper, which proves the feasibility of the method.

Magnetic integrated LLCL filter with resonant frequency above Nyquist frequency

This paper presents a design technique of magnetic integrated LLCL filters for grid-tied inverters. With the proposed design technique, the LLCL filter's resonant frequency can be higher than the Nyquist frequency. Furthermore, the proposed concept was only reported for the LCL filter in the previous research works. In addition, the modulation process will produce dominant switching harmonics for unipolar PWM H-bridge inverters at the double switching frequency. Thus, putting the resonant frequency beyond the Nyquist frequency will increase the stability zone. The proposed design methods maximize the filter inductors' utilization and resist the grid impedance variations under weak grid conditions, depending on the improved stability zone. Comparative simulation and HIL experimental results are presented to confirm the effectiveness of the proposed magnetic integrated LLCL filter design. The HIL experimental results and the simulation results agree well with each other.

New LADRC scheme for fractional-order systems

Active Disturbance Rejection Control (ADRC) is a very promising recent concept for the design of controllers to control systems with uncertainties. Based on an extended state observer, this control structure allows both external disturbances and modeling uncertainties to be actively rejected. The use of the active rejection control of disturbances is gaining more and more interest among the system control community. This is mainly due to its easy design, undemanding implementation and robustness. In this paper, three solutions using the ARDC structure to control fractional-order system are discussed. Two methods taken from the literature are briefly introduced, namely, the fractional-order dynamics rejection scheme (FODRS) and the fractional linear active disturbance rejection control (FLADRC). The basic ideas and technical formulations of these two are presented. A third method, based on the robustness performance introduced by fractional-order controllers, is also proposed in this paper. The proposed design method of the set-point tracking controller is based on the Bode’s ideal transfer function (Bode’s ITF). This will improve the robustness of the control scheme.

Self-centering rocking dual-core braced frames with buckling-restrained fuses

This paper proposes a self-centering rocking dual-core braced frame system with buckling-restrained fuses (SC-RDC-BRF). While providing low-damage design and improved seismic resilience, the proposed system prevents soft-story failure in steel braced frames. The use of buckling-restrained fuses and post-tensioned (PT) cables in the SC-RDC-BRF system enables the structure to dissipate energy and exhibit self-centering behavior effectively. The proposed rocking system does not require column uplifting and thus preventing demand amplifications on the frame members. The paper also develops a design method for SC-RDC-BRF systems. The design method is based on a preliminary design with a rigid core assumption and a modified response spectrum analysis for the design of the rocking cores (i.e., beams, columns, braces, and ties). Nonlinear static and dynamic analyses are also performed on three-, six-, and nine-story frames to verify and illustrate the design method. Results from nonlinear response history analyses confirm the adequacy of the proposed design method and expected performance of SC-RDC-BRF systems.

Three-dimensional assembled dual-material lattice with tailorable thermal expansion: Design method, modeling, and testing

The lightweight dual-material metal lattice structure with the tailorable coefficient of thermal expansion (CTE) has attracted increasing attention for aerospace applications. However, previous work on these metal structures was mainly directed to theoretical design with the limited experimental demonstration in planar geometries because it is challenging to fabricate three-dimensional (3D) metal lattices with highly complex geometric connections. In this article, we propose a node assembly dual-material lattice design method enabling the experimentally demonstrated 3D designs with the tailorable CTE. A theoretical model of the thermal expansion and mechanical properties is provided to link the thermo-mechanical properties to the configuration and base materials. Based on the proposed design method and the theoretical model, we present three geometrical layouts with experimentally demonstrated CTEs of 34.77ppm/°C, -16.21ppm/°C, and 0.05ppm/°C, respectively. Notably, the achieved CTE of 0.05ppm/°C has never been reported in previous studies. In addition, the proposed assembled lattice can be extended periodically. Based on the demonstrations, we expect that the proposed method is promising for structurally efficient lattices design with high dimensional stability in aerospace engineering.

Constant-Beamwidth Kronecker Product Beamforming With Nonuniform Planar Arrays

In this paper, we address the problem of constant-beamwidth beamforming using nonuniform planar arrays. We propose two techniques for designing planar beamformers that can maintain different beamwidths in the XZ and YZ planes based on constant-beamwidth linear arrays. In the first technique, we utilize Kronecker product beamforming to find the weights, thus eliminating matrix inversion. The second technique provides a closed-form solution that allows for a tradeoff between white noise gain and directivity factor. The second technique is applicable even when only a subset of the sensors is used. Since our techniques are based on linear arrays, we also consider symmetric linear arrays. We present a method that determines where sensors should be placed to maximize the directivity and increase the frequency range over which the beamwidth remains constant, with a minimal number of sensors. Simulations demonstrate the advantages of the proposed design methods compared to the state-of-the-art. Specifically, our method yields a 1000-fold faster runtime than the competing method, while improving the wideband directivity factor by over 8 dB without compromising the wideband white noise gain in the simulated scenario.

A subwavelength sinusoidally-shaped phononic beam structures-based metasurface for flexural wave steering

In this work, we propose a method to design subwavelength metasurfaces for flexural waves in thin plates based on sinusoidally-shaped phononic beam structures. In the proposed method, the effective bending stiffness of sinusoidally-shaped phononic beam structures is tuned, and the effective phase velocity of the flexural waves is modulated subsequently by adjusting two key geometry parameters, namely, the amplitude of the sinusoidal profiles and lattice constants of the phononic beam structures. Compared with the previous methods, which modulate a single design parameter, the proposed method is a two-parameter modulating method. Thus, it not only maintains the functionality of metasurfaces, but also is much more flexible when obtaining a high wave transmittance. In addition, the mass of functional units of metasurfaces designed by the proposed method is not relevant to the design parameters, which is particularly important in weight-critical applications. To validate the feasibility of the proposed design method, the transmission spectra of sinusoidally-shaped phononic beam structures are modeled using the finite element method, and results are compared with experiments of 3D-printed samples. In addition, two representative metasurfaces, refractive and focusing metasurfaces, are designed with an available minimum transmission coefficient of 0.93 for functional units. Numerical evaluation of these metasurfaces’ performances confirms the effectiveness of the proposed method. This work paves a novel way to design elastic metasurfaces to manipulate flexural waves in thin plates and demonstrates a potential new direction to design metasurfaces for other wave types.

Achieving Approximately Zero Ripples in Input Current of Coupled SIDO Boost Converter

This article focuses on the coupled inductor single input dual output (CI-SIDO) boost converter topology. The CI-SIDO boost converter can be used in many practical applications, such as electric vehicles, renewable energy systems, and portable electronic devices. Several applications, such as battery charging, fuel cells, photovoltaic systems, and ultracapacitors, require ripple-free currents, as the lifetime of sources in these applications gets reduced by higher current ripples. However, there is no method in the existing literature to obtain a zero-ripple input current in the CI-SIDO boost converter. This article proposes an approach to design a CI-SIDO boost converter such that the ripple in input current is either zero or less than the maximum specified ripple limit. The analytical proofs of the design method are presented, and the usability analysis is evaluated by taking practical design examples. The effect of variations in the input voltage, CI parameters, and closed-loop control on the proposed design method is analyzed. The proposed design method is verified in experiments by laboratory prototype and in LTspice simulations.

Data-driven affective product design using complete three-dimensional surface data

As the main part of design display and evaluation, product three-dimensional (3D) form is the core object in affective product design. However, previous research has not yet addressed the development of technical models and method involving complete 3D surface data, and thus cannot guarantee the quality of affective product design. By using the techniques of triangular mesh model, spherical harmonic and conditional variational auto-encoder, this paper proposes a data-driven affective product design method composed of several technical models using complete 3D surface data. These models include: mathematical model for quantifying 3D form, recognition model for recognizing customer’s affective responses, and generative model for generating new 3D forms. For affective product design, the mathematical model achieves the acquisition and processing of complete 3D surface data, the recognition model improves the objectivity and accuracy of recognition by integrating the 3D form data into the calculation process of emotion recognition, and the generative model realizes the automatic generation of new 3D forms in response to emotional data based on the recognition results. Each model provides technical support for realizing the acquisition, processing and generation of complete 3D surface data of product form, and ensures the systematicness and completeness of the proposed method for the affective product design involving 3D form innovation. The feasibility of the method is verified by an example of car design, and the results show that it is an effective affective product design method involving 3D form innovation.

Signum-Function-Based Multi-Input Multi-Output Adaptive Homogeneous Finite-Time Control for a Rigid-Body Attitude Tracking

This study is devoted to investigating the robust adaptive finite-time attitude tracking control problem for a rigid body subject to unknown uncertainties. Considering about the nonlinear attitude dynamics for a rigid body, a homogeneous sliding variable is designed by employing the signum-function technique. For the presented homogeneous sliding variable, a real sliding manifold, on which the singularity problem is avoided, could be achieved. Subsequently, a novel signum-function-based MIMO adaptive homogeneous finite-time control (SMAHFTC) algorithm is proposed. Finite-time convergence of the tracking errors to a region around the origin is rigorously proved through the Lyapunov approach. The control gains will not be overestimated, which implies that minimal control gains will be obtained by the adaptation law. Moreover, the controls’ signals are continuous for the SMAHFTC law. Then, by means of the proposed design method, an attitude tracking controller is designed for a rigid body described by the modified Rodrigues parameters’ (MRPs) representation. A comparison simulation is carried out to show the effectiveness and superiority of the proposed method.