Fundamental Design Research Articles

Developing Practical Catalysts for High‐Current‐Density Water Electrolysis

AbstractHigh‐current‐density water electrolysis is considered a promising technology for industrial‐scale green hydrogen production, which is of significant value to energy decarbonization and numerous sustainable industrial applications. To date, substantial research advancements are achieved in catalyst design for laboratory‐based water electrolysis. While the designed catalysts demonstrate remarkable performance at laboratory‐based low current densities, they suffer from marked deteriorations in both activity and long‐term stability under industrial‐level high‐current‐density operations. To provide a timely assessment that helps bridge the gap between laboratory‐scale fundamental research and industrial‐scale practical water electrolysis technology, here the current advancements in various commercial water electrolyzers are first systematically analyzed, then the key parameters including work temperature, current density, lifetime of stacks, cell efficiency, and capital cost of stacks are critically evaluated. In addition, the impact of high current density on the electrocatalytic behavior of catalysts, including intrinsic activity, long‐term stability, and mass transfer, is discussed to advance the catalyst design. Therefore, by covering a range of critical issues from fundamental material design principles to industrial‐scale performance parameters, here the future research directions in the development of highly efficient and low‐cost catalysts are presented and a procedure for screening laboratory‐designed catalysts for industrial‐scale water electrolysis is outlined.

Design for Circular Manufacturing and Assembly (DfCMA): Synergising Circularity and Modularity in the Building Construction Industry

Modular construction is emerging into the limelight in the construction industry as one of the front-running modern methods of construction, facilitating multiple benefits, including improved productivity. Meanwhile, Circular Economy (CE) principles are also becoming prominent in the Building Construction Industry (BCI), which is infamous for its prodigious resource consumption and waste generation. In essence, the basic concepts of modular construction and CE share some commonalities in their fundamental design principles, such as standardisation, simplification, prefabrication, and mobility. Hence, exploring ways of synergising circularity and modularity in the design stage with a Whole Life Cycle (WLC) of value creation and retention is beneficial. By conducting a thorough literature review, supported by expert interviews and brainstorming sessions, followed by a case study, the concept of Design for Circular Manufacturing and Assembly (DfCMA) was proposed to deliver circularity and modularity synergistically in circularity-oriented modular construction. This novel conceptualisation of DfCMA is envisaged to be a value-adding original theoretical contribution of this paper. Furthermore, the findings are expected to add value to the BCI by proposing a way forward to synergise circularity and modularity to contribute substantially towards an efficient circular built environment.

Breathable and Stretchable Epidermal Electronics for Health Management: Recent Advances and Challenges.

Advanced epidermal electronic devices, capable of real-time monitoring of physical, physiological, and biochemical signals and administering appropriate therapeutics, are revolutionizing personalized healthcare technology. However, conventional portable electronic devices are predominantly constructed from impermeable and rigid materials, which thus leads to the mechanical and biochemical disparities between the devices and human tissues, resulting in skin irritation, tissue damage, compromised signal-to-noise ratio (SNR), and limited operational lifespans. To address these limitations, a new generation of wearable on-skin electronics built on stretchable and porous substrates has emerged. These substrates offer significant advantages including breathability, conformability, biocompatibility, and mechanical robustness, thus providing solutions for the aforementioned challenges. However, given their diverse nature and varying application scenarios, the careful selection and engineering of suitable substrates is paramount when developing high-performance on-skin electronics tailored to specific applications. This comprehensive review begins with an overview of various stretchable porous substrates, specifically focusing on their fundamental design principles, fabrication processes, and practical applications. Subsequently, a concise comparison of various methods is offered to fabricate epidermal electronics by applying these porous substrates. Following these, the latest advancements and applications of these electronics are highlighted. Finally, the current challenges are summarized and potential future directions in this dynamic field are explored.

How unemployment benefit duration shapes startup motivation and growth

AbstractBusiness creation is economically important, and unemployment precedes the creation of a substantial share of new firms. Yet, most research has focused on analyzing the effects of unemployment insurance policies on re-employment outcomes, ignoring self-employment. In this paper, we analyze how the potential duration of unemployment benefits, a fundamental design choice of unemployment insurance systems, affects whether new firms are founded out of opportunity or necessity and their growth potential. To this end, we construct a comprehensive dataset on German firm founders that links administrative social insurance information with business survey data. Exploiting reform and age-related exogenous variation in the potential duration of unemployment benefits, we find that longer potential benefit duration implies longer actual unemployment and, as a consequence, more necessity entrepreneurship and worse startup outcomes in terms of sales and employment growth. We explain this overall effect of potential benefit duration through a mix of compositional and individual-level duration effects. Our findings underline that new firms started out of unemployment are a highly heterogeneous group and suggest that the (optimal) design of unemployment insurance systems has important externalities on whether innovation- and growth-oriented firms are started out of unemployment.

Reduction of N2 to NH3 using FeP(101)/TiO2 catalysts: A First-principles study

The electrochemical nitrogen reduction reaction offers an eco-friendly and sustainable way for synthesizing ammonia at room temperature, in contrast to the energy-intensive Haber-Bosch process. In this study, we demonstrate that FeP (101) is stabilized by anatase TiO2(101), resulting in the formation of a FeP/TiO2 composite. This composite shows promising potential as a catalyst for N2 electroreduction. All hydrogenation reactions are feasible and occur spontaneously, with the ∗N2-∗N2H step serving as the potential determining step (PDS) with a value of 0.59 V. In comparison to the Ru (0001) surface (1.08 V), which exhibits superior catalytic activity in nitrogen reduction reactions (NRR), the obtained value is significantly lower. FeP/TiO2 exhibits ∼100% selectivity towards ammonia synthesis as compared to the competitive hydrogen evolution process (HER). This study demonstrates that the correlation between N2 activation and the electronic structure will aid in the fundamental comprehension, design, and alteration of NRR catalysts.

Design and Implementation of a Desorption Electro-flow Focusing Sprayer on an Orbitrap Mass Spectrometer for DESI Mass Spectrometry Imaging at High Spatial Resolution and at High Speed.

Since desorption electrospray ionization mass spectrometry (DESI-MS) was first presented in 2004, the fundamental design of the sprayer has undergone relatively minor modifications. This changed in 2022 when Takats and co-workers implemented the desorption electro-flow focusing (DEFFI) sprayer design by modifying the sprayer from a commercial DESI system, leading to significantly improved spatial resolution and robustness compared with the traditional DESI-MSI sprayer design. Here, we present the design of a new DEFFI sprayer that can be built from standard fittings and connectors in combination with an aluminum spray head that can be machined in most mechanic workshops. The new design represents a cost-efficient approach to improved DESI-MSI on mass spectrometers from all vendors, including high-resolution instruments such as Orbitraps and FT-ICR. The new DEFFI sprayer is demonstrated on a QExactive Orbitrap mass spectrometer, resulting in a massively improved ion yield compared with the classic DESI sprayer. The improved ion yield enables DESI-MSI at ion injection times down to 5 ms, allowing for DESI-MSI at a potentially very high speed. More importantly, the DEFFI sprayer delivers a more robust and focused spray, which is easier to use and requires less optimization. It provides high spatial resolution with limited effort compared with previous modifications of the traditional DESI design. Imaging of rat testis was performed at pixel sizes down to 12 μm, suggesting a spatial resolution of approximately 30 μm, which may have potential for further improvement.

A radar array expansion design method based on modular subarray layout

Abstract This paper introduces a design method for expandable subarray structures used in phased array radar arrays. Based on the structural characteristics of modular subarray layout for large radar arrays, this paper analyzes the assembly dimension chain tolerance based on subarray expansion. One third of the allowable deviation of the radar array is used as the subarray design tolerance, and the size tolerance of each installation surface of the subarray is designed according to the design tolerance. Finally, the subarray array is assembled into any size of radar array, and the probability of the radar array assembly accuracy meeting the allowable deviation is 99.73%. For large radar arrays, adopting this design method can significantly reduce the tolerance span between the sub array and the area array, greatly reducing the difficulty of design and processing. This paper provides a fundamental design method for the expansion design of radar arrays with similar systems, which has universal applicability.

The RAS Paradigm in Mainframe Systems: A Comprehensive Analysis of Design Principles and Operational Benefits

This article examines the critical role of Reliability, Availability, and Serviceability (RAS) in mainframe computing systems. We explore how RAS principles have become fundamental design features in modern mainframes, enhancing their ability to meet the demanding requirements of enterprise-level data processing. The article provides an in-depth analysis of each RAS component, detailing how reliability is achieved through robust hardware self-checking and extensive software testing, availability is maintained via seamless component failover and layered error recovery, and serviceability is ensured through advanced diagnostic capabilities and modular replacement units. We argue that the holistic integration of RAS principles in mainframe architecture not only maximizes system uptime and operational continuity but also significantly impacts application design and overall system efficiency. Through a comprehensive review of current mainframe technologies and industry practices, this article highlights the enduring importance of RAS in an era of increasing computational complexity and datadriven decision making. Our findings suggest that RAS principles will continue to evolve, playing a crucial role in shaping the future of high-performance, mission-critical computing systems.

Rational Construction of Cyanide-Functionalized D-A-π-D Covalent Organic Frameworkfor Highly Efficient Overall H2O2 Photosynthesis from Air and Water.

Sacrificial-agent-free overall photosynthesis of H2O2 from water and air represents currently a promising route to reform the industrial anthraquinone production manner, but, still blocks by the requirement of pure O2 feedstock, due to the insufficient oxygen supply from water under air. Herein, we report a rational molecule design on COFs (covalent organic frameworks) equiped with cyanide-functionalized D-A-π-D system for highly efficient overall H2O2 production from air and water through photocatalytic oxygen reduction reactions (ORR) and water oxidation reaction (WOR). Without using any sacrificial agent, the as-synthesized D-A-π-D COF is found to enable a H2O2 production rate as high as 4742 μmol h-1 g-1 from water and air and an O2 utilization and conversion rate up to 88%, exceeding the other D-A-π-A COF by respectively 1.9- and 1.3-fold. Such high performance is attributed to the tuned electronic structure and prolonged charge lifetime facilitated by the unique D-A-π-D structure and cyanide groups. This work highlights a fundamental molecule design on advanced photocatalytic COFs with complicated D-A system for low-cost and massive H2O2 production.

Rational Construction of Cyanide‐Functionalized D‐A‐π‐D Covalent Organic Framework for Highly Efficient Overall H2O2 Photosynthesis from Air and Water

Sacrificial‐agent‐free overall photosynthesis of H2O2 from water and air represents currently a promising route to reform the industrial anthraquinone production manner, but, still blocks by the requirement of pure O2 feedstock, due to the insufficient oxygen supply from water under air. Herein, we report a rational molecule design on COFs (covalent organic frameworks) equiped with cyanide‐functionalized D‐A‐π‐D system for highly efficient overall H2O2 production from air and water through photocatalytic oxygen reduction reactions (ORR) and water oxidation reaction (WOR). Without using any sacrificial agent, the as‐synthesized D‐A‐π‐D COF is found to enable a H2O2 production rate as high as 4742 μmol h‐1 g‐1 from water and air and an O2 utilization and conversion rate up to 88%, exceeding the other D‐A‐π‐A COF by respectively 1.9‐ and 1.3‐fold. Such high performance is attributed to the tuned electronic structure and prolonged charge lifetime facilitated by the unique D‐A‐π‐D structure and cyanide groups. This work highlights a fundamental molecule design on advanced photocatalytic COFs with complicated D‐A system for low‐cost and massive H2O2 production.

Suppressed concentration quenching and tunable photoluminescence in Eu2+-activated Rb3Y(PO4)2 phosphors for full-spectrum lighting

Highly efficient inorganic phosphors are desirable for lighting-emitting diode light sources, and increasing the doping concentration of activators is a common approach for enhancing the photoluminescence quantum yield (PLQY). However, the constraint of concentration quenching poses a great challenge for improving the PLQY. Herein, we propose a fundamental design principle by separating activators and prolonging their distance in Eu2+-activated Rb3Y(PO4)2 phosphors to inhibit concentration quenching, in which different quenching rates are controlled by the Eu distribution at various crystallographic sites. The blue-violet-emitting Rb3Y(PO4)2:xEu (x = 0.1%–15%) phosphors, with the occupation of Rb1, Rb2 and Y sites by Eu2+, exhibit rapid luminescence quenching with optimum external PLQY of 10% due to multi-channel energy migration. Interestingly, as the Eu concentration increases above 20%, Eu2+ prefer to occupy the Rb1 and Y sites with separated polyhedra and large interionic distances, resulting in green emission with suppressed concentration quenching, achieving an improved external PLQY of 41%. Our study provides a unique design perspective for elevating the efficiency of Eu2+-activated phosphors toward high-performance inorganic luminescent materials for full-spectrum lighting.

Impact of geometric variables on the functionality of downdraft biomass gasifiers across diverse dimensions

This study offers an extensive examination of the fundamental design parameters that influence the performance of biomass downdraft gasifiers. The impact of design parameters such as reactor dimensions, throat diameter, length of converging and diverging section and ratio of maximum to minimum diameter (dmax/dmin) were analysed using FORTRAN code, which was initially developed for 4 kW Imbert gasifier. Simulation results highlight that the optimal range of hearth loads for gasifier operation is influenced by both the gasifier’s size and the particle size of the feedstock. Increasing gasifier size from 20 mm to 100 mm throat diameter, while maintaining the same superficial air velocity (SAV), escalates hearth load and superficial velocity due to heightened biomass consumption, leading to higher hearth temperature and improved gas calorific value. Similar trends are observed across varying SAV values (0.35 m/s to 1.8 m/s), suggesting a need for lower SAV values in larger gasifiers, possibly with larger particle sizes. Additionally, altering the length of the converging and diverging sections impacts gas quality, with deviations from recommended values affecting ignition and overall performance, while dmax/dmin variations show no significant impact.

On the Fundamental Tracking Performance and Design Considerations of Radio Navigation

On the Fundamental Tracking Performance and Design Considerations of Radio Navigation

Designing activities and tools to support university students' creative and collaborative exploration of physical computing

Today’s digital world requires students to gain skills in collaborative problem solving and digital literacy. One approach is to teach people how to design computational artefacts that require both electronics and programming. Physical computing platforms offer an endless amount of possible opportunities for people to design and develop technological artefacts. However, many times students are overwhelmed when trying to learn both software and hardware simultaneously. The students struggle to be innovative and creative in their projects. Also, they focus on mastering the tool and following instructions for existing projects rather than being able to creatively explore the tool and understand the process of designing and developing new artefacts. For that reason, we aimed to answer the question: What type of tools and activities can be developed to support university students creative exploration of physical computing? Programming and electronics are fundamental design disciplines in today's digital world, and therefore they should be taught through design activities rather than limiting education to textbook readings and laboratory exercises. We introduce our process of designing activities combined with a supportive tool to ease these challenges. The activities and tools were developed iteratively in three phases with a series of workshops with 126 students and teachers. The tool consists of a set of paper cards that provide necessary details (hints) about the electronics and software and help provide structure for the students to conceptualise how their artefact interacts. We additionally, introduced a learning Jigsaw pattern (orchestration script) for the later intervention that enabled individual students in the groups to focus on design, hardware, or software. For evaluation, we used the Creativity Support Index (CSI), which is a psychometric survey designed to assess the support of the creative process. The instrument investigates collaboration, efforts worth the result, exploration, immersion, enjoyment, and expressiveness. The results between the phases showed improvement with the use of the refined versions of the cards and orchestration of the learning activity. This study has demonstrated that design activities can provide a more accessible approach for the introduction of physical computing to students from various majors. Moreover, learning physical computing through design activities allows the learner to develop computational and design thinking skills for collaboratively solving problems.

Numerical study on the effects of tube inclination angle and heat conductive cover plate on freeze plug performance in molten salt reactors

The freeze plug is an important passive safety system used in the molten salt reactors (MSRs). However, although the inclination angle is one of the fundamental design parameters, its influence on the freeze plug performance has not been explored systematically. Multidimensional numerical simulations were hence carried out to analyze the effects of tube inclination on the solidification and melting processes of salt encountered in the freeze plugs of the MSRs in this work. The effects of placing a high thermal conductivity cover plate on the outer wall of the freeze plug were also investigated. In the solidification process, the tube inclination had a significant impact on the equilibrium shape of the frozen salt. A decrease in the inclination angle from the horizontal resulted in a reduction in the plug volume, and closing of the freeze plug became more difficult when the inclination angle was small and the tube diameter was large. In the melting process, natural convection induced in the liquid salt was intensified with a decrease in the inclination angle. This accelerated the melting of solid salt to shorten the opening time significantly. Optimizing the tube inclination angle was hence shown to be of great importance to improve the safety of MSRs. When a copper plate was placed on the freeze plug outer wall to facilitate the heat transfer to the frozen salt, its influence on the solidification process was not noticeable, while melting was accelerated and the opening time was reduced by about 20%.

Technical noise, data quality, and calibration requirements for next-generation gravitational-wave science

Abstract The next generation of ground-based gravitational-wave interferometers is expected to generate a bounty of new astrophysical discoveries, with sensitivities and bandwidths greatly improved compared to current-generation detectors. 
These detectors will allow us to make exceptional advancements in our understanding of fundamental physics, the dynamics of dense matter, and the cosmic history of compact objects. 
The fundamental design aspects of these planned interferometers will enable these new discoveries; 
however, challenges in technical noise, data quality, and calibration have the potential to limit the scientific reach of these instruments.
In this work, we evaluate the requirements of these elements for next-generation gravitational-wave science, focusing on how these areas may impact the proposed Cosmic Explorer observatory.
We highlight multiple aspects of these fields where additional research and development is required to ensure Cosmic Explorer reaches its full potential.

(Invited) Developing Periodically-Aligned Fibrous Structures to Suppress Lithium Dendrites for Anode-Free Batteries

We have developed electrospinning-based manufacturing capability for dendrite-free anode-free and anode-less batteries. Electrospinning is a widely used, feasible manufacturing approach to create nano- and micro-porous layers of functional fibers. By tailoring fiber compositions, the electrospun layers can afford a wide variety of functionalities applicable to biomedical templates, separation membranes, and energy storage. Its manufacturing capability is, however, limited to producing randomly oriented fibrous structures. Topology and tortuosity of the electrospun fibrous layers are poorly controlled, making it difficult to systematically investigate structure-property relationships for any given applications, especially electrochemical systems.In this presentation, we will demonstrate how to improve the controllability of fiber construction geometry by electrospinning. Unlike conventional electrospinning, our approach employs a mobile stage that allows precise alignment of fibers. Produced fibrous structures will be used to construct current collectors of the anode-free batteries, one of the proposed beyond-lithium (Li)-ion battery systems for high energy density. While direct, yet reversible, Li plating and stripping on and from the current collector has proven difficult due to uncontrolled dendrite growth, we found that the flat copper foil reinforced by the three-dimensional fibrous structure can enhance Li storage efficiency over an extended number of cycles, outperforming the planar case. We will discuss the effect of fiber compositions and controlled geometrical configurations on stabilizing Li plating and stripping morphologies to suppress Li dendrite growth and provide a fundamental design principle to construct anode-free and anode-less battery cells. Battery manufacturing advanced by this work will offer a systematic strategy to develop next-generation energy storage systems for a sustainable energy future.

Comparative Study on the Reduction of Tritium Breeding Ratio Caused by Inventory Changes of a Solid-State Tritium Breeding Blanket in a Fusion Demonstration Reactor Using MCNP and FISPACT-II

The self-sufficient supply of tritium in the deuterium-tritium nuclear fusion demonstration reactor (DEMO) is a fundamental design requirement. But, it is hindered by depletion of tritium breeding materials resulting in reduction of tritium breeding ratio (TBR) less than the initial design value especially in the solid-state tritium breeding blanket (TBB) of the DEMO. Unlike the liquid tritium breeding blanket of DEMO, compensation measures of the depleted breeding material in the solid-state TBB will be its substitution depending on the reduction rate of TBR. To estimate the replacement period of the solid-state TBB, it is required to estimate the reduction rate of TBR according to the operation conditions of the DEMO and the physical configuration of a solid-state TBB. In this study, the representative simulation codes, MCNP and FISPACT-II, are used for assessment of the reduction rate of TBR with the benchmarking model which is modified from the one poloidal segment of the TBB in the Korean-DEMO. After 3 full power-year operations with the neutron irradiation with the benchmarking model, the TBR simulated by MCNP is reduced to 96.84% of the initially calculated TBR, but the TBR calculated by FISPACT-II is reduced to 90.57% of the initially calculated TBR.

Design standards for high‐performance liquid‐solid tubular triboelectric nanogenerators

AbstractLiquid‐solid tubular triboelectric nanogenerators (LST‐TENGs) hold significant promise for environmental mechanical energy harvesting due to advantages such as low wear, long service life and simple fabrication. However, the lack of unified standards and norms of design leads the output performance still being lower than that of traditional solid‐solid TENGs. In this study, we first report a comprehensive set of standards for designing high‐performance LST‐TENGs based on several of the most critical factors, including the selection of triboelectric materials, the choice of motion modes, and the determination of structural parameters. Guided by the designing standards, the charge generation capability of LST‐TENGs is optimized and enhanced by over 100‐fold. The transferred charge can reach up to 3.4 μC, which is a new record for all kinds of LST‐TENGs. Notably, the practical application potential of design standards has been demonstrated in the actual harvesting of wave energy. This study establishes a fundamental design standard for designing high‐performance LST‐TENGs and holds excellent potential to accelerate the industrialization of TENGs.

Carbon‐Based Textile‐Structured Triboelectric Nanogenerators for Smart Wearables

Recent advances in wearable electronics have been propelled by the rapid growth of microelectronics and Internet of Things. The proliferation of electronic devices and sensors relies heavily on power sources, predominantly batteries, with significant implications for the environment. To address this concern and to reduce carbon emissions, there is a growing emphasis on renewable energy harvesting technologies, among which textile‐based triboelectric nanogenerators (T‐TENGs) stand out as an innovative and sustainable solution due to having the interesting characteristics like large contact area, lightweight design, flexibility, comfort, scalability, and breathability. T‐TENGs can harness mechanical energy from human movement and convert it into electric energy. However, one of the challenges is low electric power output, which can be addressed by meticulous selection of material pairs with significant differences in work function and optimizing contact areas. The incorporation of carbon‐based nanomaterials, such as carbon nanotubes and graphene, emerges as a key strategy to enhance output. This review delineates recent progress in T‐TENGs incorporating carbonaceous nanofillers, comprehensively addressing fundamental classification, operational mode, structural design, working performance, and potential challenges that are hindering commercialization. By doing this, this review aims to stimulate future investigations into sustainable, high‐performance smart wearables integrated with T‐TENGs.