Proposed Design Process Research Articles

Metal Additive Manufacturing Process Design based on Physics Constrained Neural Networks and Multi-Objective Bayesian Optimization

The high-dimensionality of the process-structure-property (P-S-P) relationships for metal additive manufacturing (AM) is the major research challenge for process optimization to produce defect-free, structurally sound, and reliable AM parts. The goal of this work is to investigate the feasibility of a hybrid physics-based data-driven process design framework to establish reliable surrogates of process-structure relationships for metal AM process optimization. The process design framework includes a mesoscale multiphysics simulation model to predict microstructure evolution, a physics-constrained neural network to construct the surrogate of the process-structure relationship, and Bayesian optimization for process design. The proposed framework is demonstrated by optimizing the initial temperature and cooling rate for the single dendritic growth of Ti-6Al-4V alloy during rapid solidification in metal AM so that the desired dendritic area and microsegregation level can be achieved. The multi-objective optimization problem is solved with single-objective Bayesian optimization by aggregation. The effects of the aggregation weights on the optimization results are investigated with sensitivity analysis. The results show that the weights of individual objective functions determined from design preferences can help the designer to produce desired microstructure. The Pareto front and processing map for dendritic growth are constructed with the multi-objective Bayesian optimization method. The proposed process design framework is generic and can be potentially applied in materials design and digital twins of metal AM.

A 1 THz Schottky transceiver front‐end based on 5 μm GaAs monolithic membrane

AbstractA Schottky diode‐based 1 THz Schottky transceiver front end is designed, fabricated, and measured. The terahertz mixer and tripler are fabricated with a 5 μm‐thick GaAs monolithic Schottky technology. Compact passive filter and matching network are designed to reduce the loss of transmission route. At 300 K ambient temperature, the measured minimum double‐side band noise temperature and conversion loss of 1 THz subharmonic mixer are <5000 K and 13 dB, respectively. At self‐developed available pump source, the measured maximum output power of 1 THz monolithic tripler is over 70 μW and the average output power from 960 to 1030 GHz is 35 μW. The accomplished 1 THz monolithic circuits have proved the feasibility of the proposed design process, which have certain reference value for higher frequency solid‐state Schottky‐based circuit.

Sustainable production of lignocellulosic bioethanol towards zero waste biorefinery

This study proposes a novel process design for lignocellulosic biomass to ethanol conversion with zero waste generation. In comparison to traditional bioethanol process, the proposed new process not only produces ethanol, but also converts waste streams into high value-added by-products by undergoing multi-stage refinery steps. The feasibility the proposed process design, especially the additional waste processing, has been carried out. The results showed that co-producing by-products could significantly contribute to the profitability by decreasing the ethanol minimum viable sales price from $2.24/gal to $1.78/gal, comparing with traditionally produced bioethanol. It was also found that ethanol minimum sale price is highly sensitive to the lignin price fluctuation. The water pollution can be avoided in the proposed process due to an additional water recycling step, however, there is a trade-off between reduced water pollution and increased CO2 emissions when fossil fuel is used as operation energy. The results showed that, to ensure proposed bioethanol plant have environmental advantage with traditional ethanol refinery plant, the CO2 emission per kWh for all kinds of electricity should not be over 0.11 kg/kWh. Thus, we suggest that the proposed concept of zero-waste bioethanol plants could be established in Countries with access of sufficient renewable electricity supply.

Smart product-service systems design process for socially conscious digitalization

While digitalization has become a key driver for promoting value creation for customers and stakeholders, much attention is being paid to smart product-service systems (PSS) to meet their diversified needs. When designing smart PSS, there is a strong need to consider growing concerns about the social and ethical impacts of digital technologies. Numerous ethical guidelines for digital technologies, such as artificial intelligence, have been developed. However, a more practical methodology for designing smart PSS by taking into account both positive and negative impacts (including social and ethical impacts) of using digital technologies is anticipated. This paper aims to address this issue by integrating value sensitive design into the smart PSS design process. This design process combines participatory and systematic design approaches and integrates methods to extract values and develop the specifications of complex smart PSS in an iterative manner. To demonstrate its efficacy, this paper presents a case study of a monitoring service for seniors using a communication robot. The results demonstrate that the proposed design process can support design consideration for social and ethical values and lead designers and design participants to clarify design requirements and generate a socially conscious design solution.

A Novel Single-Fed Dual-Band Dual-Circularly Polarized Dielectric Resonator Antenna for 5G Sub-6GHz Applications

In this research article, a single-fed dual-band circular polarized (CP) dielectric resonator antenna (DRA) for dual-function communication, such as GPS and WLAN, was made. Initially, the proposed design process was initiated by designing a linearly polarized singly fed-DRA. To attain CP fields, the cross-shape conformal metal strip was optimized to excite the fundamental and the high-order mode in the two frequency bands. The metallic strip (parasitic) was utilized on top of the rectangular DRA to improve and widen the impedance and axial ratio (AR) bandwidth. This step led to a 2.73% improvement on the lower band and an impact of 6.5% on the upper band while on the other side a significant improvement was witnessed in the AR bandwidth in both frequency bands. A prototype was designed and fabricated in order to validate its operations. The measurement outcomes of the proposed antennas authenticated wideband impedance bandwidths of 6.4% and 25.26%, and 3-dB axial ratios (AR) of 21.26% and 27.82% respectively. The prototype is a decent candidate for a global positioning system (GPS) and wireless local area network (WLAN).

Oblique Incidence Optimal Design of Microwave Dielectric-Magnetic Absorbing Composites

The impedance matching equation of a single-layer dielectric-magnetic absorber excited by an oblique incidence plane wave is resolved with an expression providing the optimal thickness and highlighting the composite crucial parameters. The effective propagation constant of the nonuniform refracted plane wave into the absorber is represented by a new formulation as a function of the true refraction angle which is a real number unlike the complex quantity resulting from the Snell’s law, usually applied in the literature. The proposed design process is applied to compute microwave absorption performances of different dielectric-magnetic materials, considering both normal and oblique incidence. Furthermore, the incidence angle effect is investigated.

Variable DC-Link Voltage LLC Resonant DC/DC Converter With Wide Bandgap Power Devices

Application of wide bandgap power devices enables the power electronics system to achieve higher efficiency, improved power density and reduced weight. Wide range <i>LLC</i> resonant dc&#x002F;dc converters are extensively applied in multiple scenarios, such as electric vehicle charger and renewable energy generation. In this article, the design process of a high-frequency wide-range <i>LLC</i> resonant dc&#x002F;dc converter using gallium nitride HEMTs and silicon carbide diodes is demonstrated in details. To increase the operation range, variable dc-link voltage control is utilized and investigated via analyzing the impact of the dc-link voltage on the operation point. The power loss model of the system based on the characterization results is presented and validated via simulation study. A 3.7 kW and 500 kHz experimental prototype is built to verify the proposed design process. The experimental results reveal that variable dc-link voltage control can increase power efficiency of <i>LLC</i> converter in all the operation range.

Lightweight design process considering assembly connection and non-probabilistic uncertainty with its application to machine structural design

Owing to the complexity of machines, lightweight structural design needs to consider the influence of assembly connection and non-probabilistic uncertainty in material properties. This study suggests a novel lightweight design process that incorporates these two factors. In this process, the assembly connection was modelled with the finite element model and validated by experiments. The non-probabilistic uncertainty was described using the multidimensional parallelepiped model, and then the corresponding non-probabilistic reliability-based design optimization method was applied to ensure the safety of structures. The proposed design process was applied to the structural design of the upper beam of a forming machine. The results showed that ignoring the assembly connection and non-probabilistic uncertainty may lead to an unsafe structural design, and thus they should be considered in the lightweight structural design of machines. Moreover, the weight reduction by 30.43% for the upper beam achieved using the proposed method demonstrated its effectiveness.

A pre-symptomatic incubation model for precision strategies of screening, quarantine, and isolation based on imported COVID-19 cases in Taiwan

Facing the emerging COVID viral variants and the uneven distribution of vaccine worldwide, imported pre-symptomatic COVID-19 cases play a pivotal role in border control strategies. A stochastic disease process and computer simulation experiments with Bayesian underpinning was therefore developed to model pre-symptomatic disease progression during incubation period on which we were based to provide precision strategies for containing the resultant epidemic caused by imported COVID-19 cases. We then applied the proposed model to data on 1051 imported COVID-19 cases among inbound passengers to Taiwan between March 2020 and April 2021. The overall daily rate (per 100,000) of pre-symptomatic COVID-19 cases was estimated as 106 (95% credible interval (CrI): 95–117) in March–June 2020, fell to 37 (95% CrI: 28–47) in July–September 2020 (p < 0.0001), resurged to 141 (95% CrI: 118–164) in October–December 2020 (p < 0.0001), and declined to 90 (95% CrI: 73–108) in January–April 2021 (p = 0.0004). Given the median dwelling time, over 82% cases would progress from pre-symptomatic to symptomatic phase in 5-day quarantine. The time required for quarantine given two real-time polymerase chain reaction (RT-PCR) tests depends on the risk of departing countries, testing and quarantine strategies, and whether the passengers have vaccine jabs. Our proposed four-compartment stochastic process and computer simulation experiments design underpinning Bayesian MCMC algorithm facilitated the development of precision strategies for imported COVID-19 cases.

SCIENTIFIC IMPACT OF ARCHITECTURAL INDOOR AUGMENTED REALITY 3D DIGITAL REPRESENTATIONS

This paper focuses on the scientific impact of 3D digital spatial representations in indoor architectural buildings via Augmented Reality (AR) techniques. These 3D spatial representations refer to both changes of proposed structures, design and collaboration process, guiding visitors experiences, simulations of interdisciplinary information, as well as architectural design, building geometry and modeling process in AR environment. It analyses only the scientific impact of these 3D representations aspects, highlights the innovative representation aspects and quotes main limitations and perspectives.

Conceptual Design Process for LEO Satellite Constellations Based on System Engineering Disciplines

Satellite design process is an interdisciplinary subject in which the need for collaboration among various science and engineering disciplines is evident. Meanwhile, finding an optimal process for conceptual design of a satellite, which can optimize time and cost, is still an important issue. In this paper, based on system engineering approach, an optimal design process is proposed for LEO satellite constellations. In the proposed method, design process, design sequences, and data flow are established. In this regard, the conceptual design process is divided into two levels of mission (or constellation) and system (or satellite) as well as 15 main activities based on the mission profile, previous experiences of the authors, and existing literature. Then, the relationships between these activities have been determined by considering the importance of relationships according to their priority. Finally, these relations are optimized based on design structure matrix (DSM). By utilizing this approach, system design process of a telecommunication satellite constellation in LEO is formulated in conceptual design phase. Performance and capability of the proposed approach in optimal design process of the satellite constellation are investigated by comparing the outcome with existing results in the literature.

Process development and performance assessment of flexible calcium looping biomass gasification for production of renewable gas with adjustable composition

In recent years, the field of biomass gasification as a method of transforming biomass into a more useable gaseous fuel experienced expedited development since it represents a prominent way to achieve sustainability goals and targets set by the Paris accord and, more recently, the European Green Deal. The use of natural gas is projected to reduce with the transition toward exploitation of renewable gas, while a new area of hydrogen applications is also emerging. However, with uncertain production of current processes, and consumption patterns seen on the market, an opportunity for a new flexible process exists. This article investigates a concept process design of sorption-enhanced gasification (SEG) based on calcium looping. Aspen Plus simulation software was used to develop and simulate the process models for flexible production of bio-SNG or bio-H2. The process parameters can be manipulated to either achieve a high-purity bio-H2 (>96 mol%) or high-purity bio-SNG (>95 mol%), as well as any other combination of the two main products. The concept process is based on a low-pressure, low-temperature dual-fluidized bed reactor with steam as a gasifying agent and an additional downstream Sabatier process reactor to achieve high CH4 contents. The simulated process achieves process efficiency of up to 62.2%LHV and 78.0%LHV for H2 and CH4 production, respectively, with production yields reaching 0.112 kg H2/kg BM and 0.23 kg CH4/kg BM. These values were validated and benchmarked against comparable process designs, and the performance of the proposed process was found to be on par or superior. Overall, the proposed process design exhibits clear benefits of calcium looping gasification, with high process efficiency, negligible NOx, SO2, and H2S content, and high flexibility. Therefore, the proposed process addressed and successfully solved some of the key challenges of achieving viability of a gasification plant on a commercial scale.

Mechanism for the Unfolding of the TOP7 Protein in Steered Molecular Dynamics Simulations as Revealed by Mutual Information Analysis.

We employed mutual information (MI) analysis to detect motions affecting the mechanical resistance of the human-engineered protein Top7. The results are based on the MI analysis of pair contact correlations measured in steered molecular dynamics (SMD) trajectories and their statistical dependence on global unfolding. This study is the first application of the MI analysis to SMD forced unfolding, and we furnish specific SMD recommendations for the utility of parameters and options in the TimeScapes package. The MI analysis provided a global overview of the effect of perturbation on the stability of the protein. We also employed a more conventional trajectory analysis for a detailed description of the mechanical resistance of Top7. Specifically, we investigated 1) the hydropathy of the interactions of structural segments, 2) the H2O concentration near residues relevant for unfolding, and 3) the changing hydrogen bonding patterns and main chain dihedral angles. The results show that the application of MI in the study of protein mechanical resistance can be useful for the engineering of more resistant mutants when combined with conventional analysis. We propose a novel mutation design based on the hydropathy of residues that would stabilize the unfolding region by mimicking its more stable symmetry mate. The proposed design process does not involve the introduction of covalent crosslinks, so it has the potential to preserve the conformational space and unfolding pathway of the protein.

Multi-objective optimization design and Verification of Interior PMSG Based on Finite Element Analysis and Taguchi method

This paper proposes the optimal design process of an Interior permanent magnet synchronous generator (IPMSG) for wind power systems using the finite-element analysis (FEA). A multi-objective optimization design of PM generator based on Taguchi method is proposed. This paper takes the influence of the pole arc angle, magnet inset, magnet thickness, magnet width, stator tooth width and slot depth into consideration as a design parameters. The main characteristics of generator efficiency, torque ripple and output power are taken as optimization objectives. The orthogonal matrix is established according to the number of selected parameters and the level factor of each parameter and FEM is used to solve the experimental matrix. As a result, an improved generator was designed and selected, which had higher maximum output power and efficiency and lower torque ripple. Finally, a prototype IPMSG was manufactured based on analysis results and Taguchi method, and was tested. The experimental tests were conducted to verify the validity of the proposed design process and the effectiveness of the generator and as a result, perfectly cleared the optimization design.

Design Optimization of a Synchronous Reluctance Machine for High-Performance Applications

The article presents a torque ripple minimization process using symmetrical rotor flux barrier shaping for synchronous reluctance (SyncRel) machines. High-performance applications demand stringent torque-speed, torque ripple, noise, and vibration requirements to satisfy the overall system performance. An iterative design approach incorporating electromagnetic, structural, and thermal analyses is presented that led to the design of a SyncRel motor with low torque ripple and minimized second-order vibration mode. The contributions demonstrated that the 30-slot, 4-pole SrncRel machine is a viable option for high-performance and packaging-constrained applications. Global response surface method that has the capability for parallel analysis has been used for the multiobjective optimization problem. A 2D finite element (FE) tool with the HyperStudy optimization routine has been used to implement the proposed design process. A quick and easy-to-use motor parameter-based model along with 2D FE analysis is used to evaluate the performance of the optimized design. Experimental results are provided to validate the iterative and comprehensive design, and design procedure.

Development of an ergonomic design process for smartphone hard key locations

Smartphone hard key locations need to be ergonomically determined to improve grip stability and operational efficiency for users' convenience. The present study proposed an ergonomic design process that determines smartphone hard key locations by statistically analyzing the preferred hard key control areas of users with various hand sizes based on users’ preferred grip postures and hard key control areas. The proposed design process analyzes the characteristics of product design, user, task, and use context, the types of preferred grip posture, the preference distribution of grip posture, and the preference distribution of hard-key area, and then recommends the locations of hard keys by considering the preference distribution of hard-key area and design constraints. The proposed design process was applied to a smartphone with a 5-inch screen, resulting in 77–96 mm from the bottom of the device for a volume key to 20 mm on the left side and 88–97 mm for a power key to 10 mm on the right side. The proposed design process for the determination of smartphone hard-key locations would be of use to determine the locations of various portable product interfaces.

A low-power CT 2nd order Delta Sigma modulator using a new design methodology for biomedical applications

This paper presents a low-power second-order continuous-time (CT) Delta-Sigma Modulator (DSM) using a new design methodology for biomedical applications. The proposed design methodology first implements a target block with the highest power consumption at a transistor level before optimizing the DSM coefficients. We are also able to reduce the area usage by appropriate limitations on the DSM range in the proposed design process. The DSM was implemented using the genetic algorithm (GA) and appropriate chopping techniques in our design process. The design was implemented in 0.18um CMOS technology by using a 0.083 mm2 layout, with a maximum SNDR and dynamic range of 94.28 and 100 dB, respectively, for a 2 kHz bandwidth and 32.34uW power consumption.

Design of Ultra-High-Speed Motor for FCEV Air Compressor Considering Mechanical Properties of Rotor Materials

This paper proposes the design process of an ultra-high-speed surface-mounted permanent magnet synchronous motor for a fuel-cell electric vehicle air compressor. Proposed design process enables ultra-high-speed motor design while considering mechanical stresses of the rotor materials according to the temperature. In the rotor design stage, the worst temperature condition of the permanent magnet and retaining sleeve on mechanical stress is investigated and reflected using analytical method. Rotor dimension such as permanent magnet and retaining sleeve thickness is determined considering both electromagnetic performance and mechanical characteristics. Then, from the initially designed model, the eddy current loss according to the shape ratio (SR) and torque density (TD) is analytically derived using proportional equation and finite-element analysis result. Then, SR and TD to reduce the eddy current loss and maximize the efficiency are determined while considering the first bending critical speed. Finally, to verify the proposed design process, the prototype is fabricated and tested. Test results show good agreement with the finite-element analysis results, and it is confirmed that the rotor is operated at the highest rotational speed without mechanical failure.

Integrating uncertainty quantification in reliability, availability, and maintainability (RAM) analysis in the conceptual and preliminary stages of chemical process design

Traditional analysis of a proposed process design uses average input values in the performance assessment model, thereby generating single-point estimates. The resulting estimates ignore reliability, availability, and maintainability (RAM) considerations, or assume a fixed value based on prior experience. As a result, a probabilistic view of the impact of equipment unavailability on process profitability is not considered. Recent works have proposed a financial framework for incorporating safety and sustainability considerations in the analysis of proposed designs. Based on this research, we propose a framework to integrate RAM aspects during the conceptual design stage in a probabilistic manner using Monte Carlo simulation. Subsequently, full distribution profiles of key process performance indicators are generated, including system and section availability, annual net profit, and return on investment (ROI). Probabilistic characterization of equipment availability also facilitates the prediction of potential safety and sustainability issues, as more frequent process upsets may result in increased flaring and other potential negative consequences. A modified availability metric, using restoration instead of repair times, is used in this work to obtain a more accurate view of expected downtime and thus its effects on profitability. A propane dehydrogenation (PDH) process system is used to demonstrate the application and benefits of the framework. The proposed approach allows designers and decision-makers to comprehensively assess the impacts of equipment RAM characteristics on process availability and economic performance.

Chemical product design integrating MCDA: Performance prediction and human preferences modelling

AbstractComputation‐based techniques and modelling of human knowledge and preferences by using multi‐criteria decision aid (MCDA) methods are integrated in a multi‐scale and multi‐disciplinary approach for the chemical product and process design. The proposed methodology has four main stages: (a) construction of a molecular model for predicting product performance, (b) validation of product performance, (c) selection of alternatives integrating preferences of manufacturers and consumers, and (d) process optimization implementing MCDA methods. The methodology is oriented to find new products that can replace components of formulations, whose performance is already known. It was applied to an exploratory study about the use of glycerol as raw material to produce plasticizers for polyvinyl chloride (PVC), replacing 2‐ethylhexyl phthalate (DEHP). The results of the case study and the proposed process design offer promising prospects regarding their application in other chemical products.