Practical Design Solutions Research Articles

Topology and size optimization of viscous dampers with discrete design variables by outer approximation

This article proposes a novel seismic retrofitting approach for the topology and size optimization of fluid viscous dampers using discrete design variables. The design variables are the damping coefficients of the dampers, and they are chosen from catalogues, leading to practical optimal design solutions. The optimization problems considered are formulated as 0–1 nonlinear programming problems. An algorithm based on outer approximation and that relies on first-order information is proposed to find optimized designs with modest computational resources and time. The effectiveness of the proposed approach is demonstrated through optimal seismic retrofitting of three-dimensional irregular frame structures. In the optimization problem formulation, the retrofitted structures are subjected to realistic seismic ground acceleration records with constraints on inter-storey drifts and total storey accelerations.

High-performance near-substrate heat sink with Tesla-like rotor-wing microchannel for chiplet cooling application

Microchannel heat sink provides a viable solution for enhancing thermal management in high-power chiplets. However, in consideration of cooling efficiency, low pressure drop, cost-effectiveness and reliability, it’s challenging to create an effective heat sink for a million-watt chip. Inspired by Tesla structure, this study introduces a Tesla-like rotor-wing microchannel (TRWM) to boost cooling performance. Due to the features of main channels, branch channels, and micro-islands in TRWM design, fluid in microchannel is effectively mixed and stirred with varied flow patterns, high temperature gradients and significant velocity gradients, which enhances the cooling capacity through precise fluid dynamics adjustment. Three different TRWMs are designed and compared by simulations. And the simulated results show that TRWM of 135° model achieves a maximum heat flux of 1514 W cm−2 @0.1 cm2 under a 60 K temperature rise, improving cooling efficiency by 19.4 % over the traditional channel design with 1221 W cm−2 @0.1 cm2. And then, the TRWM is fabricated using Ultraviolet Lithgraphie Galvanoformung Abformung (UV-LIGA) and bonding processes. Ultimately, the fabricated 135° TRWM sample demonstrated a heat dissipation capacity of up to 1446 W cm-2 @0.1 cm2 with a temperature increase of 60 K, which corresponds well with the simulated results. Moreover, the discrepancy between the actual and simulated values is less than 6.3 % under the same conditions. This performance provides a practical design solution for chiplet cooling and highlights the potential of bioinspired microfluidics.

An improved system design method for cell-based energy storage systems: A combination of a constraint satisfaction problem with an extended Ragone plot

Over the past three decades, advancements in electrical energy storage technologies have substantially enhanced performance and reduced costs, rendering them viable for diverse applications. Cell-based energy storage systems, such as batteries and supercapacitors, are particularly notable for their adaptability and scalable interconnection capabilities. However, the design process for such systems lacks uniform standards, presenting a gap in research for the conceptual system design. This paper introduces an improved system design method (SDM), addressing critical limitations of existing approaches: (a) Shifting from current-based to power-based requirements; (b) Enabling flexible adaptation of operational design points beyond fixed datasheet specifications; (c) Ensuring harmonization of energy storage design with other system components, notably power electronics. Central to our SDM is the novel “extended Ragone plot” (ERP), which maps cell-specific energy–power relations and allows for flexible adjustment of operational limits. Since it can be determined experimentally, the subsequent design method is model-free and can efficiently be executed for different cell types. In the SDM, this ERP is coupled with a constraint satisfaction problem (CSP) to compute a comprehensive design solution space that accommodates all application-specific requirements and component interrelations. It is implemented in a holistic, interactive tool, facilitating mathematical optimization and enabling visual analysis of energy storage system designs. As a proof-of-concept, two case studies on the design of lithium-ion battery systems for stationary grid supply demonstrate the method’s superiority over conventional approaches. While in the first case, an optimal design can be determined immediately, in the second case, there are no valid design solutions based on the cell’s initial operating point. Utilizing the ERP, a practical design solution is achieved by reducing the maximum cell power by approximately 9%, thereby modifying the cell’s available voltage and current limits. This approach provides a possible solution for scenarios where a system design based on data sheets alone is not feasible. A comparative analysis and graphical synthesis of both case studies validate this hypothesis, illustrating the novel system design method’s ability to precalculate and evaluate diverse design scenarios in advance. The source code and data used in this study are openly accessible, offering the SDM as an interactive tool for analyzing and designing energy storage systems.

Gradient enhanced physics-informed neural network for iterative form-finding of tensile membrane structures by potential energy minimization

Tensile membrane structures (TMS) are overwhelmingly popular as practical design solutions for large roofing structures. The TMS designer, however, has to perform a “form-finding” as the stable configuration of TMS are not known beforehand. Although many form-finding approaches are currently available, most suffer from various implementation complications, particularly with regards to convergence issues stemming from improper hyper-parameter selection, mesh distortion and the choice of initial reference configuration. In this study, a new iterative form-finding methodology is proposed and implemented by the direct minimization of a potential energy functional. A mesh-free approach based on gradient enhanced physics-informed neural network (gPINN) is employed, which expands the applicability to most common TMS types while eliminating the aforementioned issues faced by traditional mesh-based algorithms. Furthermore, a new method for selecting the initial reference configuration using transfinite interpolation is proposed that is significantly better suited to form-finding than conventional approaches. Additionally, approximate distance functions are employed to impose exact boundary conditions. Extensive numerical case studies on frame- and cable-supported TMS, along with multi-dimensional parametric variations, show the efficacy and robustness of the proposed form-finding framework.

Co-Innovating for Integrated Research, Teaching, and Outreach in Sea Level Rise Adaptation

Approximately 680 million people live in low-lying coastal regions susceptible to flooding (IPCC 2019), and architects are positioned to drive wide-scale adoption of practical design solutions to address climate change impacts (AIA 2020). This paper describes innovative pedagogical approaches to integrate climate change into the architectural curricula in conjunction with funded applied research and community outreach to inform future climate change adaptation. The community-engaged scholarship, Envisioning Sea Level Rise Adaptation in Waikīkī, Hawai‘i and its parallel graduate architecture courses resulted in locally tailored architectural renderings, policy guidance, and visions that may inform future design and policy. The replicable research methods describe the processes, individuals, partnerships, and products for knowledge-sharing and coordinating climate change adaptation and resilience through interdisciplinary cocreation within academia and coordinated community input.

Evaluation and continuous improvement of magnetic components material design skills in interdisciplinary switched-mode power supply

The design of switched-mode power supplies (SMPSs) is a material-electrical engineering interdisciplinary problem. The design of magnetic component materials can significantly affect SMPSs’ performances. In engineering education, the design and development of solutions is an important skill for engineering students. However, the traditional engineering experiments curriculum is shown as validation and single-disciplinary experiments as well as one-sided assessment results. To foster open-ended exploration, enhance students’ material design skills, and improve skills adaptation, students must tackle real engineering problems and develop practical design solutions. This paper proposes an exploratory factor analysis and knowledge graph-based method for evaluating and continuously improving magnetic components material design skills in the context of SMPS design tasks. First, we used the multiple imputation method to address the missing data. Each imputed data was analyzed to extract factors through parallel analysis, ordinary least squares estimation, and target rotation. Then, we identified four sub-skills: efficiency design skill, passive device design skill, power magnetic reduction design skill, and power economy design skill. The RMSEA for the four-factor model is 0.042, suggesting a good fit to the data. We established the relationships between these sub-skills and SMPS performance metrics. Furthermore, the average of the factor scores from each of the imputed datasets and the SMPS design constraints were combined to obtain the cut-off scores to evaluate engineering students’ achievements in these sub-skills. Finally, we constructed an SMPS magnetic components material knowledge graph, which could recommend specific experimental tasks, relevant knowledge areas, and SMPS performance metrics, providing personalized guidance to designers.

Closing the Perception-Reality Gap for Sustainable Fresh Food Plastic Packaging

The global discourse surrounding plastics has been marked by a profound perceptual schism, also for plastic packaging in the fresh food industry. The public opinion expresses mounting concerns in terms of such plastic packaging solutions. However, in many cases the unique material properties and the well-established methodology of Life Cycle Assessment (LCA) actually demonstrate the environmental advantage of plastics for food packaging. This paper delves into the chasm between the two perspectives, leveraging empirical evidence to resolve the divide.While performing both a consumer analysis and LCA, this paper underscores the potential for innovative, yet practical design solutions to harmonise the public opinion with counterintuitive positive environmental impacts. A transformative design solution that centres around the concept of shape and material renewal is proposed. It demonstrates how a simple, yet effective redesign can enhance both the environmental impact and consumer acceptance in the industry for mass-produced fresh food packaging. It emphasises the role of LCE in design, with a focus on the pre-consumer phase. The findings provide a practical approach, emphasising the need to reconcile theory with consumer desires, to forge a sustainable path forward in packaging design.

High Stability of Broadband Photomultiplier Organic Photodetector with metal ion-chelated polymer as an electron tunneling injection dipole layer

Broadband photomultiplier organic photodetectors (PM-OPDs) have tremendous potential for use in a variety of photoimaging, physical health monitoring, and wearable applications. However, the interfacial mismatch between electrodes and organic semiconductors inhibits the long-term working stability and reliability of devices. Here, we devised high-performance and stability PM-OPDs by using Zn2+-chelated ethoxylated-polyethylenimine (denoted as PEIE-Zn) as an electron tunneling injection dipole layer between ITO and P3HT:PC71BM: Y6 (3:20:80) broadband photoactive layer. The specific detectivity of the PEIE-Zn-modified PM-OPDs was higher than 1012 Jones in the whole spectral response range (350–1000 nm) under 10V bias. The external quantum efficiency of the device exceeded 1000 % in the whole spectral response range under −20V bias. The transient photoresponse curve of the device has no obvious peaks and fluctuations, and the photocurrent density drops only 2.34 % and 0.25 % at 10 V and −20 V bias after illumination, respectively. The device exhibited very good stability over the course of a week, with its photocurrent density maintained at more than 98.94 % of the initial photocurrent density in the ambient environment without encapsulation. This work improves interface contact by modifying the ITO electrode with PEIE-Zn, providing a practical design solution for devices with high response and stability for broadband PM-OPDs.

Judicious design solutions for zero energy school buildings in hot climates

The concept of net-zero energy, with its holistic consideration of energy-efficient passive, active, and renewable energy systems, is a critical step toward decarbonizing the built environment. This work aims to assess the feasibility of net-zero energy schools in hot climates and propose practical and realistic design solutions. The design of a net-zero energy school was developed and analyzed using DesignBuilder software in hot-humid, hot-dry, and warm-humid climatic zones in Oman. A multiphase methodology was followed, including data collection, an energy audit, fieldwork measurements, and energy simulation modeling. Integrating judicious passive design strategies such as thermal insulation for walls and roofs besides high-performance windows resulted in moderate potential reductions in energy cost and consumption in all climatic zones. Considering active design strategies like light-emitting diode (LED) lights, lighting control, and variable refrigerant volume/variable refrigerant flow (VRV/VRF) air conditioning systems resulted in additional reductions in energy cost and consumption. For the energy cost, the reductions were estimated at 29.9%, 29.5%, and 25.9% in the hot-humid, hot-dry, and warm-humid climatic zones, respectively. The corresponding reductions in energy consumption reached 28.53%, 27.90%, and 25.14%. Integrating a photovoltaics (PV) system aiming to reach the net-zero energy status supplied the school with demanded energy and managed to export 42.78%, 43.53%, and 45.75% to the national grid in the hot-humid, hot-dry, and warm-humid climatic zones, respectively. Similar reductions were achieved for CO2 emissions and energy costs.

Hybridity and Multiscale Compatibility in Landscape Infrastructure for Mountain River Restoration: A Pathway Toward Environmental and Socio-Ecological Sustainability

River rehabilitation has traditionally focused on hard-engineering projects, which often fail to address environmental protection concerns and social-ecological services in a larger territorial context. In particular, mountain rivers pose unique challenges due to their diverse hydrological and morphological conditions, which are often overlooked by traditional restoration methods. Consequently, water quality deteriorates and social-ecological imbalances arise. To address these challenges, we propose a holistic solution that integrates landscape infrastructure (LI), a soft-engineered biophysical structure and process. Our approach combines hydrological analysis, ecological sensitivity assessment, and ecological design solutions to develop an LI framework for the Xiaojiahe basin in the Chongqing Mountain range in southwest China. This framework emphasizes integration across the spatial scale of landscape networks and corridors. Our study reveals the existence of fragmented river systems and limited connectivity among green spaces in the research area. The adoption of a comprehensive Landscape Infrastructure (LI) framework facilitates the execution of culturally sensitive and practical design solutions for Mountain Urban River Restoration (MURR) at different levels. This approach reinstates the multifaceted environmental and socio-ecological benefits of the basin. We believe that our approach can be applied to other cases with similar contexts and challenges.

The Potential of Focusing Acoustic Retroreflectors for Architectural Surface Treatment

How much sound can a building surface reflect to a source, the location of which is not exactly known? This paper considers this question particularly for a planar surface acting as an array of retroreflectors, or of focusing retroreflectors. The question is investigated using finite-difference time-domain acoustic simulation, using ideal retroreflective patches achieved by space-reversal, and focusing achieved by delays. Extensive (7.2 × 7.2 m) and local (2.4 × 2.4 m) ideal planar reflector arrays were investigated at distances of 1.5 to 4 m from sources that were within a 2.4 × 2.4 m square plane. Patch sizes ranged from 0.3 m squares to the full reflector size. Physically realizable non-ideal focusing retroreflectors based on parabolic trihedra were also investigated. With sufficiently large patches, ideal focusing retroreflector arrays consistently outperform non-focusing retroreflector arrays. A large focusing retroreflector array has the potential to provide retroreflected energy levels (speech and A-weighted) from the first reflection to a source at 2 m distance comparable to the diffuse field energy level of acoustically supportive reverberant rooms. A small focusing retroreflector array returns less sound, but still much more than a single reflection from an equivalent specularly reflecting surface. Results from parabolic trihedra demonstrate that retroreflected energy levels similar to those from ideal surfaces can be achieved by architectural form. Challenges in translating these concepts to practical design solutions are discussed.

'Feminine horror' or 'eminent Viennese specialty'? : Vienna's Kunstgewerblerin in Paris, 1925

This article focuses on the Austrian contribution to the 1925 Exposition des Arts D�coratifs et Industriels Modernes in Paris and the role of the modern woman designer (Kunstgewerblerin) in light of the exhibition's focus on the modern female consumer. Tracing how women's contributions were seen as significant only when emphasising the pavilions shortcomings in offering truly modern (meaning practical and functional) design solutions, the article draws on debates about gender and the purpose of modern design, about the luxurious nature of the decorative arts in Vienna, and about the contested figure of the Kunstgewerblerin as a profession and a type of modern femininity. It argues that the 'female factor' in Austria's participation in Paris epitomised a moment when women's contributions to interwar Austrian design were being renegotiated in relation to the social, cultural, and economic concerns after the First World War

Fire dynamics inside a large and open‐plan compartment with exposed timber ceiling and columns: CodeRed #01

SummaryThere is an increasing global demand to build from timber as it is a sustainable and attractive material. One of the key challenges associated with timber buildings is their performance in a fire, in particular, for medium‐ and high‐rise buildings and when timber is exposed. Research on this topic to date has been performed in compartments smaller than 84 m2 which does not capture the fire dynamics of large compartments. This paper presents the first in a series of experiments carried out inside a large, purpose‐built, open‐plan compartment with a floor area of 352 m2. The large‐scale compartment had a fully exposed, unloaded, cross‐laminated timber (CLT) ceiling and glued laminated timber (glulam) columns, made with adhesives that have been tested to not exhibit char fall‐off in fire. At 352 m2 floor area, this is currently the largest compartment fire experiment carried out globally. The compartment characteristics and the arrangement of the wood crib mimicked the previous series of experiments in Poland in a non‐combustible compartment by Rackauskaite et al. (2021). The experiment was instrumented with thermocouples measuring the gas temperature in the compartment, and above two of the openings, as well as the temperature within the timber members. Plate thermometers were also included to measure the heat flux to the ceiling and of the external flaming. Additionally, fixed and drone‐mounted cameras captured the fire. A protected steel column was added to calculate the equivalent fire exposure when compared to a standard fire resistance furnace test. The experiment was allowed to burn out without fire‐fighting intervention. Continuous measurements were taken for 48 h. The wood crib was ignited at one end of the compartment. Flames rapidly spread across the timber ceiling to the other end of the compartment with the rest of the wood crib being involved in the fire at 5 min 36 s from ignition. The total duration of the fire was 22 min 30 s, at which time visible flaming ceased. Significant external flaming was observed through the openings in the order of 3 m in height but varied with position as the fire travelled across the compartment. Analysis of the experimental results and camera footage showed that the presence of the timber structure approximately doubled the heat release rate (HRR) compared to the value expected from the wood crib alone. Smouldering combustion of the timber members continued for hours after the cessation of flaming, burning in several hotspots, resulting in holes through the CLT slab. This paper improves the understanding fire dynamics for open‐plan, exposed timber compartments and has shown that issues such as external flaming, smouldering and the increase in HRR need to be considered when deriving practical design solutions.

Benefits of a hygienic, efficient and smart solution for ventilation systems in the era of the “New Normal”

Ventilation with external air is one of the most effective strategies to eliminate pathogens from indoor environments. The Air Handling Unit (AHU) is the heart of the ventilation system in commercial buildings and it is designed to achieve this goal. The guidelines for the reduction of the risk of spreading the Sars-CoV2-19 virus have introduced new operating criteria for ventilation systems, which counterbalance a better healthiness of the air in rooms with a higher energy consumption. Unfortunately, there is no standardized and shared approach to date for the designer to use as a starting point to balance these two different needs. Therefore, engineers should be aware of and pay a greater attention to the identification of practical and effective design solutions. This document proposes a technological solution for AHUs based on three key principles: Hygiene, Energy Saving and Digitization. We propose a complete and integrated architecture for the recovery of energy, humidification, system control and continuous monitoring of operating conditions, capable of ensuring health and safety, on the one hand, in compliance with the main guidelines, such as VDI 6022, and of increasing the overall efficiency of the equipment, on the other hand. The analysis compares this innovative solution with several conventional functional schemes or with systems otherwise linked to the new requirements emerged with the pandemic, and shows the resulting economic benefits, even for different climate conditions. The result shows how the selection of integrated systems for the control of ventilation, energy recovery and humidification is a winning solution that ensures healthy environments, while simultaneously reducing operating costs

Topology optimization design related to size effect using the modified couple stress theory

Traditional topology optimization methods based on classical mechanics can provide practical design solutions for macroscale structural design. However, the rapid development of additive manufacturing, with high-resolution and rapid prototyping characteristics, has promoted their wider application in microscale or nanoscale structures. Furthermore, when the characteristic size of the macroscopic deformation field of the structure is reduced to the microscale or nanoscale, the size effect causes the structure’s mechanical response to be inconsistent with the macroscale structure. Owing to the lack of microscopic characteristic parameters in the constitutive model, the traditional topology optimization framework based on the classical mechanics framework cannot accurately describe the size effect. To solve the topology optimization problem related to the size effect, a general framework that combines the modified couple stress theory with the bi-directional evolutionary structural optimization (BESO) method is constructed to explore the size effect on topology optimization.

Guidelines for Topology Optimization as Concept Design Tool and Their Application for the Mechanical Design of the Inner Frame to Support an Ancient Bronze Statue

For the past few decades, topology optimization (TO) has been used as a structural design optimization tool. With the passage of time, this kind of usage of TO has been extended to many application fields and branches, thanks to a better understanding of how manufacturing constraints can achieve a practical design solution. In addition, the advent of additive manufacturing and its subsequent advancements have further increased the applications of TO, raising the chance of competitive manufacturing. Design for additive manufacturing has also promoted the adoption of TO as a concept design tool of structural components. Nevertheless, the most frequent applications are related to lightweight design with or without design for assembly. A general approach to integrate TO in concept designs is still missing. This paper aims to close this gap by proposing guidelines to translate design requirements into TO inputs and to include topology and structural concerns at the early stage of design activity. Guidelines have been applied for the concept design of an inner supporting frame of an ancient bronze statue, with several constraints related to different general design requirements, i.e., lightweight design, minimum displacement, and protection of the statue’s structural weak zones to preserve its structural integrity. Starting from the critical analysis of the list of requirements, a set of concepts is defined through the application of TO with different set-ups (loads, boundary conditions, design and non-design space) and ranked by the main requirements. Finally, a validation of the proposed approach is discussed comparing the achieved results with the ones carried out through a standard iterative concept design.

How the COVID 19 pandemic would change the future of architectural design

PurposeThe purpose of this research is to conduct a comparative analysis of the views of architects and urban designers in the West and the Middle East on whether the COVID-19 pandemic could affect architecture and urban design shortly and what is the future of our home design? A further purpose was to explore and explain how the pandemic will change the future of architecture and urban design by reviewing, analyzing and synthesizing different and related viewpoints to create a grounded theory, hoping to provide some insight for the entire world.Design/methodology/approachDifferent research methods were used to achieve the research purposes including grounded theory, desk reviews, reviewing the limited existing literature and semi-structured interviews.FindingsThis research found that most surveyed architects believed that the COVID-19 pandemic would affect the future of architecture and urban design and help to create new design features. Future concentration will be in living, working, learning, leisure and teaching spaces. All future designs should be independent, self-sufficient in terms of power and water usage and using nonrenewable energy sources. The home design should focus on the interior design, transparency, open to the inside (introverted spaces), quality of life, natural daylighting and ventilation, healthy indoor air quality, use of plants and natural materials, green roof, the relationships between indoor and outdoor spaces and quality of building materials. Additionally, transitional space is an important primary entry point to the home. Moreover, folding furniture may be a solution to enlarge the room when needed and turn it into multifunctional spaces. The home office will no longer be a small desk, chair and lamp located at the small corner anywhere. The future home office should be equipped with all the necessary technology. The open-plan design trend and the concept of flow space will not exist anymore. The pandemic will encourage the use of touchless and smart technologies in design and construction. There is a need to separate heating and ventilation systems in detached houses and multistory buildings to avoid infectious diseases. Social norms have changed over a few weeks of social distancing. Therefore, we can change the system of negative habits, old traditions and society’s bad behaviors.Practical implicationsThis research raises many proactive ideas, and the results are relevant to all actors in the construction sector, as it contains findings of understanding how the interaction of people with the built external or internal environment evolved during the pandemic process. In this sense, it will provide socio and economic benefits for the society in terms of seeking an answer to the question of “how should we design” for possible new bad scenarios to evolve the spaces in the “lockdown” situation. This research discusses how to make our homes comfortable and ready for an extraordinary time, suggested a practical design solution based on construction technologies.Social implicationsThis research links theory to practice, and it facilitates the adaptation to the current situation. It has a high impact on society, as it guides designers to rethink spaces that can help occupants face the COVID-19 pandemic challenges. Therefore, it should create and implement architectural design guidelines for health and safety. The architects should think about how to create and organize multifunctional, flexible, aesthetical, healthy and clean spaces under the new roles of interaction and social distancing. Architects should incorporate technological and innovations from different fields to organize spaces, promote public health and enhance the quality of life.Originality/valueArchitecture and urban design suddenly become medical, and we can use the built environment as a way to control epidemic spread. Additionally, and by reviewing the literature, there is no published qualitative research that has been explored on how the COVID-19 pandemic will change the future of architecture and urban design, but there are some personal viewpoints and short interviews. This topic is a new growing concern and becoming a top social topic and priority for policymaking in the world. The topic is important in terms of design input for designers to create new living spaces, as it includes the views and observations of architects from the east and west to the pandemic process. We have all been encouraged to reimagine the space in which we live, how the place fits our needs, how we use it and enjoy it during the pandemic. Therefore, this paper appeals to an international readership by linking the COVID-19 situation to architectural design.

Design optimization and sensitivity analysis of simply supported prestressed concrete girders: A two dimensional non-linear paradigm

This paper presents a practical optimum design solution of prismatic simply supported prestressed concrete girders that are subjected to uniformly distributed static loads. The process is formulated as a nonlinear optimization model while assuming linear elastic behavior and employing the working stresses method. The process produces the optimum values of two design variables, namely the cross-sectional dimensions and the prestressing force. Those optimized values are computed to satisfy either a minimum weight or a minimum cost objective function. To solve the nonlinear programming models, a program named Nonlinear Programming Prestressed Concrete Optimizer (NLPRECO) was coded in MATLAB® programming environment. Some illustrative design problems were solved using NLPRECO, and their results are demonstrated herein. Sensitivity analysis of the optimized design variables, to variations in design parameters, was also investigated, and the results are presented. Results show substantial improvement over the regular un-optimized solutions and moderate improvement over linear programming optimization solutions.

Experimental characterisation of different hermetically sealed horizontal, cylindrical double vessel Integrated Collector Storage Solar Water Heating (ICSSWH) prototypes

Existing Integrated Collector Storage Solar Water Heaters (ICSSWHs) are typically simple and low-cost devices that combine heat collection and storage functions in one unified vessel. However, during non-collection periods they are affected by higher heat loss characteristics when compared to standard solar collector systems. This paper introduces the design evolution of new horizontal cylindrical ICSSWH prototypes developed at Ulster University that use novel, patented double vessel, thermal diode features (to enhance heat retention during non-collection periods) achieved by incorporating a liquid–vapour phase change material (PCM) with a very low pressure annular cavity. The energy performance evaluation and characterisation of different prototype designs under solar simulated experimental conditions has been conducted and the subsequent parametric analysis presented. A balance between performance and physical/operational considerations is necessary to ensure that new and practical design solutions (in materials, fabrication and assembly) can be formulated to improve the performance of the ICSSWHs within the limits of commercial reality. The importance of augmenting heat transfer across the annulus cavity has been demonstrated with improvement of the cold-start daily collection efficiency from around (ηcol) of 20% (no HTF), to > 55% when the annulus is evacuated to remove non-condensable gases and form a liquid–vapour phase change thermal diode. Annulus thermal diode heat transfer coefficients of around (Ufr) 35 W/m2K in forward mode and 2 W/m2K in reverse mode have been demonstrated. Diurnal thermal efficiencies (ηcol24) of 22% have been measured, but values of 39% have been identified as achievable in the longer-term development of presented ICSSWH.

Dynamic properties of fibre reinforced foamed urethane composites in wet and dry conditions

Advanced materials such as plastics and composites have been invented and adopted for bespoke products in railway industry. For instance, they have been employed as railway track sleepers, switches and crossings’ bearers, bridge transom girders, and so on. Railway track sleepers and bearers are essential for operations that enhance safety and reliability of railway turnouts. The degradation mechanism of railway sleepers/bearers is attributable largely to the type of materials used. The utilisation of composite material as turnout bearers, located in railway switches and crossings, has resulted in many questions whether they can experience aggressive environments. In reality, the dynamic properties of bearers play a key role in the serviceability performance of the switches and crossings. Exposed to high-intensity impact loading condition, switches and crossings withstand excessive vibrations, which can disable crawlock or signalling gear systems. Even though such effects are well-known, the influence of environmental variance on the dynamic properties of the bearers has yet been determined thoroughly. The goal of this investigation is to identify the influence of wet and dry conditions for the practical guideline and design solutions using composite materials for railway turnout systems. In this investigation, ‘fibre-reinforced foamed urethane (FFU)’, is emphasized since FFU has been installed in several railway switches and crossings globally. The dynamic properties of the FFU materials will be identified using the instrumented impact hammer testing method. The dynamic damping property of FFU can be calculated by exponential curve fittings, and logarithmic decrements. The results show that FFU on average absorbs less than 5% of water. Interestingly, the water absorption has led to the increment in dynamic moduli in both fibre-grain directions up to 16%.