Key Design Criteria Research Articles

Impact of damaged housing on the performance of field aged composite High Voltage Insulators

Composite High Voltage Insulators (HVIs) are lightweight, inexpensive, and offer superior pollution performance. Consequently, they have replaced ceramic HVIs in highly contaminating coastal and desert regions. However, they are prone to degradation in harsh environments. In this paper, we assess the performance of three identical field-aged 380 kV composite HVIs with a service life of twelve years near the western coastal region of the Kingdom of Saudi Arabia. The housing of all the HVIs showed widespread damage, including cracks on sheds and shanks, partially or fully broken sheds, and rusted end fittings. The changes in morphology and material composition were assessed through SEM and EDX. An electrical breakdown test in the presence of steam fog revealed lowered withstand strength. Electric field distribution, a key design criterion for an HVI, was studied using the Finite Element Model (FEM) of the insulator bearing physical defects. The results reveal localized electric field intensification caused by all types of defects, notably smaller and narrower ones. Our findings indicate that while physical defects in HVIs can cause localized electric field intensification, they are not a significant concern unless accompanied by severe hydrophobicity loss, compromised electrical withstand levels, or extensive erosion exposing the fiberglass rod and jeopardizing mechanical stability.

Benchmark of mixed-integer linear programming formulations for district heating network design

Optimal routing and investment decisions are key design criteria to reduce the high investment costs of district heating systems. However, these optimization problems have prohibitively high computational costs for large districts. Four different mixed-integer linear optimization frameworks are benchmarked in this study in order to compare their computational scaling. The frameworks exhibit significant differences in solving times for synthetic benchmarks and real-world urban districts of up to 9587 potential edges. The new open-source framework topotherm, developed for this work, exhibits the best computational performance when only one time step is optimized. The comparison between the models Résimont, DHmin, DHNx, and topotherm shows two main trends. First, fewer integer variables do not necessarily translate to lower solving times, and second, using redundant binary variables, which introduce symmetries into the constraints, leads to higher solving times. None of the considered optimization frameworks is able to solve the largest benchmark problems for five time steps within the allowed time limit and tolerance. These findings highlight the challenges of and pressing need to develop efficient models for simultaneous optimization of district heating network topology, pipe sizing, and operation.

Aluminium-Silicon Lightweight Thermal Management Alloys with Controlled Thermal Expansion

With the ever-growing emphasis on global decarbonization and rapid increases in the power densities of electronics equipment in recent years, new methods and lightweight materials have been developed to manage heat load as well as interfacial stresses associated with coefficient of thermal expansion (CTE) mismatches between components. The Al–Si system provides an attractive combination of CTE performance and high thermal conductivity whilst being a very lightweight option. Such materials are of interest to industries where thermal management is a key design criterion, such as the aerospace, automotive, consumer electronics, defense, EV, and space sectors. This paper will describe the development and manufacture of a family of high-performance hypereutectic Al–Si alloys (AyontEX™) by a powder metallurgy method. These alloys are of particular interest for structural heat sink applications that require high reliability under thermal cycling (CTE of 17 μm/(m·°C)), as well as reflective optics and instrument assemblies that require good thermal and mechanical stability (CTE of 13 μm/(m·°C)). Critical performance relationships are presented, coupled with the microstructural, physical, and mechanical properties of these Al–Si alloys.

An aero-structure-acoustics evaluation framework of wind turbine blade cross-section based on Gradient Boosting regression tree

Under the rapid development of wind turbines, the rotor size has substantially increased in recent years. To meet the key design criteria, finding a trade-off between aerodynamic, structure and noise (ASN) impact becomes a challenging problem. The blade cross-section is the basic element of the blade, its outer contour is the airfoil profile that produces aerodynamic loads as well as noise, and the inner part is the supporting composite material that provides enough stiffness to balance the loads. Modifying local blade sections can adjust the rotors’ overall performance. However, in the work of blade-combined ASN optimization, the iterative process using traditional numerical simulation methods becomes extremely heavy. In this study, a sustainable database is created based on a large number of calculations of aerodynamic, structural and noise attributes at various cross-sections. Then a platform named AFML (Airfoil machine learning) for simultaneously predicting the comprehensive performance of the cross-section is constructed by using the integrated Gradient Boosting Regression Tree algorithm. Results show that the prediction accuracy of AFML is acceptable even for unseen inflow conditions. By calling the pre-trained AFML, ASN data of the cross-section can be immediately obtained, and the blade shape and inner structure can be updated quickly.

Methodology of Eco-Design and Software Development for Sustainable Product Design

In the face of the growing social recognition of environmental awareness and emerging regulations in countries where targets include the reduction of the CO2 footprint in the industrial sector, several companies are facing the challenge of introducing environmental impacts as new key design criteria. To successfully launch new products with optimized environmental impact, it is crucial to apply Life Cycle Assessment (LCA) during the design phase. However, the design process of any product is a process where materials, production processes, concepts, and various design factors are constantly changing, which requires an agile LCA calculation for its effective inclusion during the iterative design process. This paper presents an eco-design methodology, based on the adaptation of the LCA method to the changing design environment, through the adaptation of LCA stages to the design process, the customization of environmental databases to the product of the company, and the development of a software tool for its application during the earlier design phases. This methodology assists designers to save efforts during the calculation process, with different integration levels of environmental data, according to LCA phases established by ISO 14040 and ISO 14044. The effectiveness of this methodology will be shown with a real case study.

Advances in 3D Bioprinted Cardiac Tissue Using Stem Cell-Derived Cardiomyocytes.

The ultimate goal of cardiac tissue engineering is to generate new muscle to repair or replace the damaged heart. This requires advances in stem cell technologies to differentiate billions of cardiomyocytes, together with advanced biofabrication approaches such as 3D bioprinting to achieve the requisite structure and contractile function. In this concise review, we cover recent progress in 3D bioprinting of cardiac tissue using pluripotent stem cell-derived cardiomyocytes, key design criteria for engineering aligned cardiac tissues, and ongoing challenges in the field that must be addressed to realize this goal.

Design and Validation of Miniaturized Repetitive Transcranial Magnetic Stimulation (rTMS) Head Coils.

Repetitive transcranial magnetic stimulation (rTMS) is a rapidly developing therapeutic modality for the safe and effective treatment of neuropsychiatric disorders. However, clinical rTMS driving systems and head coils are large, heavy, and expensive, so miniaturized, affordable rTMS devices may facilitate treatment access for patients at home, in underserved areas, in field and mobile hospitals, on ships and submarines, and in space. The central component of a portable rTMS system is a miniaturized, lightweight coil. Such a coil, when mated to lightweight driving circuits, must be able to induce B and E fields of sufficient intensity for medical use. This paper newly identifies and validates salient theoretical considerations specific to the dimensional scaling and miniaturization of coil geometries, particularly figure-8 coils, and delineates novel, key design criteria. In this context, the essential requirement of matching coil inductance with the characteristic resistance of the driver switches is highlighted. Computer simulations predicted E- and B-fields which were validated via benchtop experiments. Using a miniaturized coil with dimensions of 76 mm × 38 mm and weighing only 12.6 g, the peak E-field was 87 V/m at a distance of 1.5 cm. Practical considerations limited the maximum voltage and current to 350 V and 3.1 kA, respectively; nonetheless, this peak E-field value was well within the intensity range, 60-120 V/m, generally held to be therapeutically relevant. The presented parameters and results delineate coil and circuit guidelines for a future miniaturized, power-scalable rTMS system able to generate pulsed E-fields of sufficient amplitude for potential clinical use.

Assessment of cyclic superposition approaches for the cyclic design of monopiles supporting offshore wind turbines

One of the key design criteria for the design of monopiles supporting offshore wind turbines is limiting the permanent rotation accumulated through its lifetime (Igoe et al., 2022). In geotechnical design practice, macro-modelling approaches are often used to assess the cyclic accumulated rotation. They requires 4 key components: (1) a static model, (2) a cyclic model for accumulating rotation for a given load package, (3) a superposition model for accumulating rotation between different load packages (4) an unloading model to assess the final permanent accumulated rotation once unloaded. The majority of literature focuses on the cyclic models. This paper assesses the effect of using different cyclic superposition models. A new superposition approach is proposed which matches well with the results from a high-quality field test from the literature. The paper compares the permanent accumulated rotation from four widely used semi-empirical cyclic models (Hettler, 1981, Solcyp, 2017; Leblanc et al., 2010a, Klinkvort and Hededal, 2013) used in conjunction with four different superposition approaches. The results demonstrate that the choice of superposition approach can be as important as the choice of cyclic model, which is often overlooked in the literature but is critical for the estimation of accumulated permanent rotation.

The Role of Microorganisms in the Isolation of Nanocellulose from Plant Biomass

The isolation and bottom-up assembly of nano-cellulose by using microorganisms offers unique advantages that fine-tune and meet the main key design criteria of sustainability, rapid renewability, low toxicity and scalability for several industrial applications. As a biomaterial, several properties are required to maintain the quality and functional period of any product. Thus, researchers nowadays are extensively using microorganisms to enhance the yield and properties of plant nanocellulose. A microbial process requires approximately 20%–50% less energy compared to the chemical isolation process that consumes high energy due to the need for intense mechanical processing and harsh chemical treatments. A microbial process can also reduce production costs by around 30%–50% due to the use of renewable feedstocks, fewer chemical additives, and simplified purification steps. A chemical isolation process is typically more expensive due to the extensive use of chemicals, complex processing steps, and higher energy requirements. A microbial process also offers higher yields of nanocellulose with well-defined and uniform dimensions, leading to improved mechanical properties and enhanced performance in various applications, compared with the chemical isolation process, which may result in a wider range of nanocellulose sizes, potentially leading to variations in properties and performance. The present review discusses the role of different microorganisms (bacteria, yeasts and fungi) in the isolation and production of nanocellulose. The types and properties of nanocellulose from different sources are also discussed to show the main differences among them, showing the use of microorganisms and their products to enhance the yield and properties of nanocellulose isolation. Finally, the challenges and propositions regarding the isolation, production and enhancement the quality of nanocellulose are addressed.

A universal Birkhoff pseudospectral method for solving boundary value problems

Inspired by the well-conditioned spectral collocation method of Wang et al., a new Birkhoff pseudospectral method for solving boundary value problems is proposed. More specifically, we develop new Birkhoff interpolants that jointly satisfy boundary conditions on both the derivatives and values of the dependent variable. This key design criterion obviates the need to generate different Birkhoff matrices for different boundary conditions while maintaining the O(1) condition number with respect to N, where, N2 is the size of the Birkhoff matrix. In addressing the resulting theoretical and numerical problems, we generate computationally efficient and stable formulas for producing the new Birkhoff matrices. Furthermore, by transforming a generic mth order differential equation to its canonical form, we show that the same first-order Birkhoff matrix can be repeatedly used to solve a wide variety of boundary value problems. Illustrative numerical examples demonstrate the generality, simplicity and utility of the new approach.

Ventilated improved pit latrine: a theoretical evaluation of conventional design guidelines, user adaptations and prospects for improvement

The ventilated improved pit latrine has the potential of meeting the sanitation needs of many households in developing countries and enhance the chances of attaining the Sustainable Development Goal (SDG) 6. However, some user adaptations of the technology appear to conflict with conventional design guidelines and may compromise the ventilation rate in the vent pipe. This would negatively affect the odour control function of the technology. This paper seeks to evaluate existing conventional design guidelines that are aimed at controlling odour and fly nuisance in the latrine to highlight their relevance and possible conflicts with existing and emerging user adaptations. It also identifies potential structural modifications that may be adopted to accommodate emerging user preferences without compromising the odour control mechanism. The review shows that, indeed, some construction practices such as provision of windows in multiple sides of the superstructure adversely affect the ventilation rate and could lead to odour problems. However, the effects of some suspected unfavourable user adaptations such as use of closed-top vent caps and ceramic seats with covers have not been investigated. Furthermore, recent studies have demonstrated the possibility of compensating for the negative effect of some user preferences with favourable environmental conditions such as high wind speed and structural modifications using a mathematical model. However, the existing model fails to account for some key design criteria and needs to be improved to make it useful for a wider application.

Standardization of Power-from-Shore Grid Connections for Offshore Oil & Gas Production

Offshore oil and gas (O&G) production is typically powered by local diesel engines or gas turbines. Power-from-shore (PFS) is an alternative that takes advantage of onshore renewable production and reduces greenhouse emissions but is limited to bespoke projects that are tailored to the characteristics of each site. This lack of repetition leads to an increase in the construction risk, delivery time, and lifecycle costs, therefore limiting their large-scale deployment. Furthermore, the absence of standardized designs is also notorious in mature applications such as offshore wind farms (OWF) despite their long-standing track record, with the negative consequences extensively covered in the literature. This research paper addresses offshore transmission standardization in two parts. First, by providing the scientific community with a review of the existing offshore O&G production and substations and secondly, by outlining a lean optioneering algorithm for the cost-optimized and technically feasible selection of the key design criteria. The exercise is centred on the main limiting component of the transmission systems—the cables. As such, it addresses their operational range and the cost to calculate the most effective configuration in terms of voltage and rated power. The end goal, based on the spread of connection proposals, is to cluster the candidates to a limited set of grid connection options, the achievement of which the model has been shown to be adequate.

Key technologies disclosure for the high-g shock tester based on collision principle and experimental study.

The shock tester based on a three-body, single-level velocity amplifier is especially suitable for high-g shock tests of lightweight and compact pieces. This study focuses on disclosing some key technologies that affect whether the velocity amplifier could achieve a high-g level shock experimental environment. Equations describing the first collision are deduced and some key design criteria are proposed. The key conditions for formation of the opposite collision are proposed for the second collision, which is the most important point, to obtain a high-g shock environment. A test platform was constructed, and experiments were conducted with different shock rods, pulse shapers, and initial velocities. The test results fully demonstrated the powerful ability of the single-level velocity amplifier for high-g shock experiments and tell us that a duralumin alloy or carbon fiber is suitable to design shock rods.

Immersive experience framework: a Delphi approach

ABSTRACT The concept of immersion has been widely used for the design and evaluation of user experiences. Augmented, virtual and mixed-reality environments have further sparked the discussion of immersive user experiences and underlying requirements. However, a clear definition and agreement on design criteria of immersive experiences remains debated, creating challenges to advancing our understanding of immersive experiences and how these can be designed. Based on a multidisciplinary Delphi approach, this study provides a uniform definition of immersive experiences and identifies key criteria for the design and staging thereof. Thematic analysis revealed five key themes – transition into/out of the environment, in-experience user control, environment design, user context relatedness, and user openness and motivation, that emphasise the coherency in the user-environment interaction in the immersive experience. The study proposes an immersive experience framework as a guideline for industry practitioners, outlining key design criteria for four distinct facilitators of immersive experiences – systems, spatial, empathic/social, and narrative/sequential immersion. Further research is proposed using the immersive experience framework to investigate the hierarchy of user senses to optimise experiences that blend physical and digital environments and to study triggered, desired and undesired effects on user attitude and behaviour.

Controlling the interfacial dipole via functionalization of quinoxaline-based small molecules for electron transport layer in organic light emitting diodes

Optoelectronic devices with organic semiconductors, such as organic light-emitting diodes (OLEDs), have received much attention because they offer ease of processing and device flexibility. However, practical application of these devices is still hindered by relatively poor device performance and lack of cost-effective fabrication process, which represent properties largely determined by the molecular dipole moments of the organic molecules. In this study, we designed and prepared novel quinoxaline-phosphine oxide small molecules (QPSMs) as the electron transport layer (ETL) for the solution-processable OLEDs by tuning the end functional group of the aromatic QPSMs. A key design criterion was controlling the dipole moments of QPSMs, which confers (1) convenient deposition on the emission layer without further annealing through solubility in isopropanol and (2) improved electron injection/transport behavior through effective band level matching of the devices. In particular, the optimized OLEDs with (4-(2,3-bis(4-methoxyphenyl)quinoxalin-5-yl)phenyl)diphenylphosphine oxide (MQxTPPO1) exhibit external quantum efficiency (EQE) of 6.12%. Our results demonstrate the potential application of QPSMs as next-generation ETLs in organic semiconductors.

Women’s access to land and the Land Administration Domain Model (LADM): Requirements, modelling and assessment

Beyond international guidelines and agreements, over the last decade the focus of the global development community turned to collaboratively designing technical methodologies and tools to support women’s access to land. The Land Administration Domain Model (LADM) provides a prime example of one of these technical initiatives. Whilst LADM was developed with the aim to support the access to land for women and vulnerable groups as a key design criterion, many other potentially conflicting requirements influenced the developed model. Moreover, after a decade of the standard being in practice and applied in various country contexts, there now exists the impetus and opportunity to assess whether the LADM can support the access to land for women and vulnerable groups in practice, including an assessment of the standard against new international standards and agreements emerging over the previous decade. This paper therefore assesses the gender sensitivity of the LADM, from a technical perspective, which is needed to better understand and therefore support and strengthen the documentation and recordation of women’s land rights through standard based systems, and basic datasets. The research type ‘modelling’ is followed to identify requirements from related land administration literature, and to model and match these with the current Edition I of the LADM. The status of the current version of the LADM with regards to whether, and if how it deals with these requirements was assessed. Potential actions for improvements to the LADM were recorded and some examples illustrate options of people to land relationships considering a women perspective and how the LADM would currently model those people-to-land relationships. The assessment shows that the LADM contains significant functionality to support women’s access to land and hence support the implementation of a gender sensitive land administration system. The potential and importance of standards, such as the LADM, and their role in the recognition of women’s land rights is shown and therefore future developments and uptake of such standards are seen as imperative for the 2030 Agenda for Sustainable Development.

Relationship among air void microstructural characteristics, stiffness, and fatigue of asphalt concrete mixtures

It is a common sense that the air void content significantly affects the field performance of asphalt mixtures. Thus, this parameter is a key mix design criterion and is also adopted as a quality assurance/control tool. Even though the air voids play a notorious role in the behaviour of asphalt mixtures, the knowledge about their microstructural characteristics is still limited. To overcome this limitation, advanced techniques such as the X-ray micro-computed tomography technology may be pursued as an alternative. This paper uses X-ray micro-computed tomography to identify microstructural parameters of air voids within asphalt mixtures, i.e. distribution, content, type, size, and degree of anisotropy. These microstructural characteristics are compared to the stiffness and the resistance to fatigue cracking of asphalt mixtures. The findings suggest that the air void distribution is strongly correlated with the mixture stiffness and fatigue behaviour, and that the air void heterogeneity should be avoided.

Multi-objective optimisation of a sloped-motion, multibody wave energy converter concept

The WaveTrain device is a wave energy converter concept designed to extend the high performance of buoys that undergo sloped motion into a deep water environment. It achieves this by mechanically interconnecting a series of sloped modules, amongst which restorative forces can be exchanged in order to prevent detrimental pitching motion, whilst sufficiently free motion along the inclined axis is retained. Importantly, this circumvents the requirement of a rigid seabed connection, but introduces a potential vulnerability of operational failure of the rotational joints that link each connecting strut to the adjacent module. In this paper, the impact of considering the fatigue damage accumulating at the joints, in addition to the power extraction, is investigated with regards to the optimal design of the WaveTrain device. A specially-tailored multi-objective genetic algorithm is used to explore the optimal design candidates with two variants of the pair of conflicting objectives (power extraction and fatigue damage). Some key design criteria are then presented, with reference and comparison to the design criteria that are considered optimal when only power extraction is considered.

Hydrogels for Tissue Engineering: Addressing Key Design Needs Toward Clinical Translation.

While the soft mechanics and tunable cell interactions facilitated by hydrogels have attracted significant interest in the development of functional hydrogel-based tissue engineering scaffolds, translating the many positive results observed in the lab into the clinic remains a slow process. In this review, we address the key design criteria in terms of the materials, crosslinkers, and fabrication techniques useful for fabricating translationally-relevant tissue engineering hydrogels, with particular attention to three emerging fabrication techniques that enable simultaneous scaffold fabrication and cell loading: 3D printing, in situ tissue engineering, and cell electrospinning. In particular, we emphasize strategies for manufacturing tissue engineering hydrogels in which both macroporous scaffold fabrication and cell loading can be conducted in a single manufacturing step – electrospinning, 3D printing, and in situ tissue engineering. We suggest that combining such integrated fabrication approaches with the lessons learned from previously successful translational experiences with other hydrogels represents a promising strategy to accelerate the implementation of hydrogels for tissue engineering in the clinic.

Design and analysis of biomass-to-ammonia-to-power as an energy storage method in a renewable multi-generation system

To solve the problem of unevenly distributed renewables and increase their penetration, large-scale energy storage is necessary. Green hydrogen is suitable for bulk energy storage; however, it still faces storage problems. Therefore, green ammonia has been proposed as a substitute for hydrogen. The combination of renewables and green ammonia production can achieve cross-sector decarbonization. However, the potential of green ammonia as an energy carrier requires further investigation. This paper reports the design and analysis of a renewable multi-generation system for electricity, heat, and green ammonia, where biomass-to-ammonia-to-power is used as an energy storage method. This concept combines renewable power generation, biomass chemical-looping ammonia production, and direct ammonia fuel cells. The results indicated that the maximum energy and exergy efficiencies were 60.1% and 56.3%, respectively. The system provides 29,582 t·y-1 ammonia and 3,525,305 t·y-1 hot water and captures 171,550 t·y-1 of carbon dioxide. The optimal proportion of key components and relevant design criteria were also determined through sensitivity analysis as well. Compared to systems involving power-to-ammonia-to-power, the higher efficiency, lower electricity consumption for ammonia production, and carbon dioxide capture make biomass-to-ammonia-to-power a promising energy storage method for multigeneration systems.