General Design Approach Research Articles

Mo-Doped/Ni-supported ZnIn2S4-wrapped NiMoO4 S-scheme heterojunction photocatalytic reforming of lignin into hydrogen

A novel and general approach for the rational design of a S-scheme heterojunction coupled with doping and co-catalyst modification via a reduction strategy assisted by thermal dissolution for photocatalytic HER.

Using Synthesis and Analysis for Design in Systems Engineering: an Integrated Approach

ABSTRACTThis article presents a complete and general approach for the preliminary design of systems in the framework of systems engineering by relying mainly on synthesis. It is completed by a validation step through analysis to reduce furthermore the space of admissible solutions. This approach focuses on the modeling of design problems in electrical engineering and of their solving by including non‐functional requirements right from the start through a single process. Starting from the specification of the requirements, the proposed approach develops the construction of synthesis models of design problems and their solving using the DEPS problem modeling language and the DEPS Studio environment based on Constraint Programming and Object‐oriented modeling. Concepts related to this approach include in particular the issue of reusability of models, notions of subdefinite systems and of problem, knowledge and solutions spaces.

Crosscutting Multiscale Modeling of Electrolysis Cells for Accelerating Materials R&D

Numerical models are tools that can be used to a) elucidate fundamental phenomena that are difficult to observe/resolve experimentally, and b) observe device performance as a function of materials properties and operating conditions. The latter use is particularly valuable for informing the design of cell components and accelerating their implementation at practical scales. This presentation will discuss multiple modeling approaches for electrochemical cells and the corresponding computational methods used to solve them. We will describe how high-fidelity models can be used to analyze cell components by assessing their performance, lifetime, and reliability.In our approach, a general framework for electrochemical modeling is constructed using principles of conservation of mass, momentum, charge, energy, and species. Then, application-specific, user-defined source terms are implemented which generally account for chemical and electrochemical reactions. These source terms are translated to all the conservation equations mentioned above, which expands the functionality of the computational fluid dynamics software and allows the basic modeling approach to be very flexible. Through the specific mathematical descriptions for the molecular conversion processes, such as H2 production or CO2 electrolysis, the modeling methods can be readily adapted to various electrochemical cell architectures as a general approach for component and device design or performance optimization.After validating to lab-scale experimental data, the models can be used to perform sensitivity studies on the material properties to predict the most impactful avenues for developing a system component. In addition, existing component designs can be compared to determine which is better suited to a particular application. Ranges of operating conditions can be explored in silico to observe their effect on performance at a much faster rate than can be investigated experimentally. Examples of using this approach in the past include: Analyzing the performance of various thin foil LGDL designs for low temperature proton exchange membrane electrolysis cellsStudying the effect of operating conditions on the leakage current phenomena in proton conducting solid oxide electrolysis cellsInvestigating the role of the thickness of the catholyte buffer layer in low temperature CO2 electrolysis cells These diverse applications demonstrate the usefulness of the generalized modeling framework.This presentation will demonstrate how computational modeling can link experimental materials research with the final component or product design and help close the gap between innovation and implementation. Our approach facilitates materials R&D and advances computational tools to support industry and other high technology readiness level efforts. These insights are used to inform the device design and obtain performance, degradation, and life cycle predictions, which are then used to accelerate material implementation into a finalized product.

Flexural–torsional failure and DSM design of fixed-ended cold-formed steel columns at elevated temperatures

Recently, Dinis et al. (2019,2020) reported in-depth numerical investigations showing that the current Direct Strength Method (DSM) global design curve may severely underestimate the flexural–torsional (FT) failure loads of fixed-ended cold-formed steel (CFS) columns with slenderness above 1.5. This finding was based on the analysis of columns exhibiting various cross-section shapes and geometries, and covering wide slenderness ranges. Moreover, these authors used the failure load data gathered to develop, and propose a novel DSM column strength curve set that was shown to improve considerably the FT failure load prediction for those columns. The purpose of this work is to extend the scope of the previous investigations to fixed-ended CFS cold-formed columns failing in FT modes under elevated temperatures (up to 800 °C). The results presented and discussed consist of column FT post-buckling equilibrium paths and failure loads, obtained through geometrically and materially non-linear Ansys shell finite element analyses — to ensure covering wide FT slenderness ranges, several room-temperature yield stresses are considered. The model prescribed in Part 1–2 of Eurocode 3, for cold-formed steel, is adopted to describe the temperature-dependence of the steel material properties. Lastly, the numerical failure loads assembled in this work, together with numerical and experimental ones collected from the literature, are used to propose a modification of the DSM-based FT strength curve set developed by Dinis et al. (2020), making it capable of handling FT failures under elevated temperatures. Since the merit assessment of the modified strength curve set shows a visible improvement in FT failure load prediction quality, it is fair to argue that it constitutes a good starting point to search for an efficient general DSM-based design approach for CFS columns failing in FT modes at elevated temperatures.

A general design approach toward covalent organic frameworks for highly efficient electrochemiluminescence

Electrochemiluminescence (ECL) plays a key role in analysis and sensing because of its high sensitivity and low background. Its wide applications are however limited by a lack of highly tunable ECL luminophores. Here we develop a scalable method to design ECL emitters of covalent organic frameworks (COFs) in aqueous medium by simultaneously restricting the donor and acceptor to the COFs’ tight electron configurations and constructing high-speed charge transport networks through olefin linkages. This design allows efficient intramolecular charge transfer for strong ECL, and no exogenous poisonous co-reactants are needed. Olefin-linked donor-acceptor conjugated COFs, systematically synthesized by combining non-ECL active monomers with C2v or C3v symmetry, exhibit strong ECL signals, which can be boosted by increasing the chain length and conjugation of monomers. The present concept demonstrates that the highly efficient COF-based ECL luminophores can be precisely designed, providing a promising direction toward COF-based ECL phosphors.

Nanomaterial-Based Dual-Emission Ratiometric Fluorescent Sensors for Biosensing and Cell Imaging.

Owing to the unique optophysical properties of nanomaterials and their self-calibration characteristics, nanomaterial-based (e.g., polymer dots (Pdots) quantum dots (QDs), silicon nanorods (SiNRs), and gold nanoparticle (AuNPs), etc.) ratiometric fluorescent sensors play an essential role in numerous biosensing and cell imaging applications. The dual-emission ratiometric fluorescence technique has the function of effective internal referencing, thereby avoiding the influence of various analyte-independent confounding factors. The sensitivity and precision of the detection can therefore be greatly improved. In this review, the recent progress in nanomaterial-based dual-emission ratiometric fluorescent biosensors is systematically summarized. First, we introduce two general design approaches for dual-emission ratiometric fluorescent sensors, involving ratiometric fluorescence with changes of one response signal and two reversible signals. Then, some recent typical examples of nanomaterial-based dual-emission ratiometric fluorescent biosensors are illustrated in detail. Finally, probable challenges and future outlooks for dual-emission ratiometric fluorescent nanosensors for biosensing and cell imaging are rationally discussed.

Exploring data-driven building energy-efficient design of envelopes based on their quantified impacts

Building performance design plays a key role in reducing the energy consumption of buildings. However, the widely used simulation-based design is facing several challenges, such as the labor-intensive modeling process and the performance gaps between design stage estimations and operational energy use. For these reasons, artificial intelligent methods are expected by designers to improve the efficiency and reliability of building energy-efficient design. To date, there has not been a practical data-driven design method of envelopes. This study aimed at exploring data-driven building energy-efficient design of envelopes based on their quantified impacts. A feature selection method and a game-theoretic method were applied to quantify the impacts of envelopes on space heating and cooling energy, which were performed on two building datasets, one of which is from the U.S. and the other from China. Random forest classifiers were developed to conduct the study. Based on discovered energy patterns and quantified impacts of envelopes on energy consumption, a rectified linear design method of envelopes was proposed with the idea of improving the performance of high-impact envelopes. Besides, a validation study was conducted on two office buildings in the hot-summer cold-winter region. To design the envelopes of a building, the data-driven analysis was driven by its similar buildings other than the whole dataset. Moreover, a detailed energy simulation was conducted to evaluate the energy performance of different design solutions. The results showed that compared with baseline design solutions, new strategies could save 1.05%–21.2% energy for space heating and cooling for these two case buildings. The proposed method is a general building envelope design approach and allows designers to easily find an energy-efficient configuration of envelopes. This study demonstrated the feasibility and effectiveness of the data-driven energy-efficient design of building envelopes.

Distributed adaptive stabilization

In this paper we consider distributed adaptive stabilization for uncertain multivariable linear systems with a time-varying diagonal matrix gain. We show that uncertain multivariable linear systems are stabilizable by diagonal matrix high gains if the system matrix is an H-matrix with positive diagonal entries. Based on matrix measure and stability theory for diagonally dominant systems, we consider two classes of uncertain linear systems, and derive a threshold condition to ensure their exponential stability by a monotonically increasing diagonal gain matrix. When each individual gain function in the matrix gain is updated by state-dependent functions using only local state information, the boundedness and convergence of both system states and adaptive matrix gains are guaranteed. We apply the adaptive distributed stabilization approach to adaptive synchronization control for large-scale complex networks consisting of nonlinear node dynamics and time-varying coupling weights. A unified framework for adaptive synchronization is proposed that includes several general design approaches for adaptive coupling weights to guarantee network synchronization.

A Novel Fe and Cu Bimetallic Mixed Porous Carbon Material for Oxygen Reduction

Non-noble metal electrocatalysts for oxygen reduction reaction are essential for the sustainability and cost reduction of energy conversion devices. However, the performance of non-noble metal catalysts is far inferior to that of platinum-based catalysts. It remains a challenge to synthesize high-performance non-noble metal catalysts using simple methods. Iron and copper are the core elements of hemoglobin and hemocyanin, which are the main components of oxygen carried in animals. Based on the above inspiration, a novel Fe and Cu bimetallic mixed porous carbon material was synthesized by a one-step method. Our catalyst Fe-Cu–N/C-F-1.5 had a porous structure, and its specific surface area is 625 m2 g−1. Fe–Cu–N/C–F-1.5 exhibited an excellent electrochemical characteristic with an initial potential of 0.98 V and a half-wave potential of 0.85 V, which could achieve better electrochemical activity than commercial Pt/C. This work provides a general approach for the rational design of transition metal and heteroatom mixed porous carbon electrocatalysts. A Fe- and Cu-doped carbon catalyst, Fe–Cu–N/C–F-1.5, is prepared from melamine, polytetrafluoroethylene (PTFE), and FeCl3, (CH3COO)2Cu•H2O by a one-pot method. Fe–Cu–N/C–F-1.5 with a porous structure and its specific surface area is 625 m2 g−1. Fe–Cu–N/C–F-1.5 shows good catalytic performance in ORR processes. The ORR half-wave potential of Fe–Cu–N/C–F-1.5 is positively shifted by 35 mV compared with that of commercial Pt/C.

Fast-Turnaround Design and Modeling Techniques for a Fast-Transient Digital Low-Dropout Regulator With 3 mV Ripples

This article presents a low-complexity digital low-dropout regulator (DLDO) design featuring a novel voltage regulation and transient enhancement scheme, and a charge-redistribution-based ripple suppression (CRRS) technique that smooths output by redistribution of excessive energy via a small capacitor. Also proposed is a fast-turnaround general DLDO design approach comprising a hybrid discrete-continuous DLDO model and techniques for modeling nonlinear performance enhancement techniques, with which a DLDO's performances for given specifications can be evaluated in the early design stage to shorten the development time. A DLDO test chip fabricated using 110 nm CMOS technology shows a fast settling time of 67 and 250 ns for light-to-heavy (i.e., 2.5 and 50 mA) and heavy-to-light transient, and an output voltage ripple as low as 3 mV with proposed CRRS. The core occupies only 0.022 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , thanks to the resource-sharing architecture of a proposed digital controller and hardware simplicity. With an input voltage of 1 V and output voltage of 0.85 V, proposed design achieves a peak current efficiency of 99.6% with a 100 MHz operating clock frequency.

Novel concepts for the design of moulds and equipment for expanded polymer bead foams

Metal additive manufacturing is proposed as route for the manufacturing of moulds for expanded polymer parts. The traditional tools used in steam-chest moulding technologies can be replaced by lighter moulds accurately designed and produced by the laser-powder bed fusion technology, with significantly reduced thermal capacity and optimized ability to homogeneously deliver the steam throughout the part volume. The general design approach is described and the performance of the innovative tested solution is presented by the discussion of a case study. The experimental tests carried out on the moulds and moulding equipment prototypes showed remarkable reduction in cycle times and energy consumption when compared to a traditional steam-chest moulding used to print the same product.

General design principle for structured light lasers.

Using custom laser cavities to produce as the output some desired structured light field has seen tremendous advances lately, but there is no universal approach to designing such cavities for arbitrarily defined field structures within the cavity, e.g., at both the output and gain ends. Here we outline a general design approach for structured light from lasers which allows us to specify the required cavity for any selected structured light fields at both ends. We verify the approach by numerical simulation as well as by an unwrapped cavity experiment. The power of this approach is that the cavity can be designed to maximise the overlap with the available pump for higher powers, minimise thermal effects for higher brightness, and at the same time output a desired structured light field that may differ substantially from the gain-end profile. These benefits make this work appeal to the large laser communities interested in cavities for high brightness and/or customized output beams.

Blends of poly(ester urethane)s and polyesters as a general design approach for triple‐shape memory polymers

AbstractPoly(ester urethane)s represent a widely investigated class of thermoplastic polymers that exhibit a thermally triggered dual shape memory effect. This behavior is the result of urethane‐rich hard segments that define the permanent shape, while domains formed by the crystallizable polyester segments act as the memory switch. We show here that blending poly(ester urethane)s with a second polyester having a different melting temperature is a straightforward and possibly general approach to create triple‐shape memory polymers, in which two different temporary shapes can be programmed. To demonstrate this, we blended a poly(ester urethane) containing crystallizable poly(1,4‐butylene adipate) segments with poly(butylene succinate) or poly(hexamethylene dodecanoate). The blends microphase separate and the different polyester segments form separate semicrystalline domains, which serve as switching elements that can be activated at different temperatures. The blends retain attractive mechanical properties and the shape memory characteristics are characterized by high fixities (70%–96%) and recovery rates (82%–94%).

A general isogeometric polar approach for the optimisation of variable stiffness composites: Application to eigenvalue buckling problems

This study presents a general approach for the multi-scale design of variable stiffness composites (VSCs). The first-level problem of the multi-scale two-level optimisation strategy (MS2LOS) is solved to determine the optimal distribution of the VSC stiffness properties at the macroscopic scale satisfying the requirements of the problem at hand. In this phase, the VSC laminate is modelled as an equivalent homogeneous anisotropic plate whose behaviour is described in terms of polar parameters (PPs), which vary locally over the structure. The First-order Shear Deformation Theory is used to take into account the influence of the transverse shear stiffness on the mechanical response of the VSC and Basis Spline (B-Spline) surfaces are employed to represent the PPs fields. In this background, the expression of the gradient of the buckling factor is determined analytically by exploiting the properties of the polar formalism and of the B-Spline surfaces. Moreover, the effect of the discrete variables, involved in the definition of the B-Spline surfaces, on the performances of the optimised solution is investigated. The effectiveness of the approach is proven on two benchmark problems dealing with the maximisation of the first buckling load of a VSC laminate, subject to feasibility and geometric requirements, taken from the literature. The results obtained by means of the MS2LOS based on the polar formalism outperform those reported in the literature, which are obtained through an optimisation strategy based on lamination parameters.

Generalized Design Approach of a Family of Grid-Connected Converters Based on Active Virtual Ground Technique for Single-Phase AC Microgrid Applications

The paper presents the state-of-the-art technique Active Virtual Ground (AVG) in the design of single-phase grid-connected converters which fully covers the entire applications on AC microgrids. Based on the three main components of the microgrid, the presented topologies belonging to the AVG series are divided into three different groups, which are associated with power consumers, renewable energy, and energy storage systems. The whole series of the single-phase converters are also based on the latest AVG technique. Therefore, in each application, a corresponding single-stage AVG converter can be found, which has high efficiency, low leakage current, and continuous grid current. The topology advantages and the working principle of the AVG converter family are demonstrated through the circuit evaluation and are experimentally verified in a set of 650 to 800 W prototypes which shows a good agreement on between both of the experimental results and theoretical finding.

Multi-objective optimisation of user experience in mobile application design via a grey-fuzzy-based Taguchi approach

User experience is a key quality of mobile application design. It involves all aspects of human–computer interactions, and thus the optimisation of user experience is a multi-objective optimisation problem. User experience is subjective and uncertain; however, very little attention has been directed toward this issue when optimising user experience. In this article, a grey-fuzzy-based Taguchi approach is proposed to optimise user experience in mobile application design. Design analysis is first conducted to determine mobile design patterns and user experience characteristics. Next, a Taguchi experiment is executed, and then the signal-to-noise ratios are computed. After that, the signal-to-noise ratios are transformed into a multi-response performance index via a grey-fuzzy-based analysis. Finally, based on the multi-response performance index, the optimal design is achieved by using statistical analysis. A mobile health application design was employed to illustrate the proposed approach. The results indicate that this approach can effectively manage the subjectivity and uncertainty concerning user experience characteristics, and can be used as a general robust design approach for optimising user experience of mobile application design.

Topology design of general tensegrity with rigid bodies

This study presents a general approach to the topology design of tensegrities with rigid bodies. To the best of the authors’ knowledge, all existing topology design methods of tensegrities focus on tensegrities that only consist of members carrying axial forces, which are referred to herein as classic tensegrities. However, another category of tensegrities, referred to as general tensegrities, contains rigid bodies aside from axially loaded members. The equilibrium and stability conditions of general tensegrities are different from those of classic tensegrities because of the existence of rigid bodies, which makes the existing topology design methods invalid for general tensegrities. In this study, the equilibrium and stability conditions of general tensegrities are first derived. A topology design approach for general tensegrities is then proposed based on a mixed-integer linear programming optimization scheme. The topology (i.e., member connectivities) is treated as a binary variable, and the member forces are treated as continuous variables. Three essential attributes, namely self-equilibrium, unilateral member force, and class-k condition, of a general tensegrity, as well as some other practical requirements, are formulated as constraints. Different objective functions are employed to design different general tensegrities. Some well-known general tensegrities are reproduced, and various numerical examples are presented to verify the effectiveness and versatility of the proposed approach. The proposed topology design method is verified to be a truly general approach for the topology design of tensegrities with or without rigid bodies.

Application of general multilevel factorial design approach in forced convection and subcooled flow boiling heat transfer to CuO/water nanofluids

In this research, heat transfer in forced convection and subcooled flow boiling to CuO/water nanofluids was experimentally and theoretically investigated. The effects of various parameters comprising subcooling temperature, nanoparticle concentration, heat flux, and fluid flow rate on the heat transfer performance of the system were studied. The general multilevel factorial design approach was applied in order to design the experiments and statistically analyze the results. Results showed that all the aforementioned factors were statistically significant. A reduced quadratic model was presented to predict the heat transfer coefficient. The suggested model was in good agreement with the experimental data. It was found the heat transfer coefficient increase as the heat flux and fluid flow rate increase while the trend was reversed for the effect of subcooling temperature. Raising the nanoparticle concentration initially deteriorated the heat transfer coefficient while a further increase in concentration enhanced the heat transfer coefficient.

Generalized Design Approach on Industrial Wireless Chargers

The paper briefly discusses the most important standards and regulations established for high-power wireless power transfer systems and introduces the main issues concerned with the conceptual design process. It analyses the electromagnetic design of the inductive magnetic coupler and proposes key formulas to optimize its electrical parameters for a particular load. The method applies to both the resistive load and the battery charging. It also suggests basic topologies for conceptual design of power electronics and discusses its proper connection to the grid. The proposed design strategy is verified by experimental laboratory measurement including analyses of the leakage magnetic field.

A general approach to minimal mass tensegrity

This work is motivated by the fundamental questions in engineering mechanics: Does continuum guarantee a minimal mass structure? What is a more mass efficient way to design structures? Moreover, what are the fundamental laws of the new approach? This paper provides a general unified approach for the minimal mass design of any solid or hollow bar tensegrity structures with any given external forces subject to the structure equilibrium conditions and the maximum stress constraints of structure members (strings yield, bars yield or buckle) in a compact matrix form. The methodology yields several nonlinear programming problems. Local stability is assured by checking the modes of failure of all the structure members, and global stability is guaranteed by solving a linear matrix inequality with the derived stiffness matrix. To further reduce mass, the choice of the cross-section of bars are also discussed. For practical problems, joint mass is considered as a penalty to the total structure mass. The principles developed in this paper demonstrates a fundamental insight into both materials and structures.