RSS 1.0Engineering and Digital Technology Publications
Browse by
All items in Bradford Scholars are protected by copyright, with all rights reserved.
Recent Submissions
-
Bending performance of SFCBs reinforced UHPC beams prestressed with FRP barsThis study investigates the bending performance of ultra-high-performance concrete (UHPC) beams reinforced with non-prestressed steel-FRP composite bars (SFCBs) and prestressed fiber-reinforced polymer (FRP) bars. The finite element software ABAQUS was used to simulate the strain behaviors of materials, applying a real strain model for concrete and equivalent plastic strain models for reinforcements. Six beams with different concrete types and reinforcements (prestressed or non-prestressed) were simulated and analyzed. These simulations yielded results that closely aligned with the results tested. Based on the validated FE models, a parametric analysis was conducted to examine the effects of mechanical properties of concrete, mechanical property of non-prestressed reinforcement, and the reinforcement ratio of prestressed FRP bars and non-prestressed SFCB on the bending performance of SFCBs reinforced UHPC beams prestressed with FRP bars. The results indicate that, as the concrete strength increases from C35 to UHPC140, both the bearing capacity and ultimate deflection of flexural beams exhibit a gradual increase. Notably, employing UHPC100 as the matrix results in specimens achieving the highest ductility, deformation, and energy absorption. When non-prestressed FRP bars are replaced by SFCBs, the ultimate load of the beams decreases by 8%, but energy absorption increases by 34%. With an increase in the steel ratio of SFCBs, the ductility, deformation, and energy absorption also gradually increase. Moreover, increasing the reinforcement ratio of both prestressed FRP and non-prestressed SFCBs results in an increase in bearing capacity, but a decrease in ultimate deflection, ductility, deformation, and energy absorption capacity. This research can provide valuable technical references for the analysis and design of UHPC beams reinforced with SFCBs and prestressed FRP bars.
-
Bending performance of reactive powder concrete frame beams reinforced with steel-FRP composite BarsTo investigate the bending behavior of Steel-FRP Composite Bars (SFCBs) reinforced Reactive Powder Concrete (RPC) frame beams, both experimental and theoretical study were conducted on five concrete frame beams with different reinforcement ratio, types of concrete and reinforcement. The results indicate that the bending behavior of SFCBs-RPC frame beams progresses through three distinct stages: from loading to the cracking of tensile RPC, from cracking to the yielding of tensile SFCBs, and from yielding to failure. Compared with steel-reinforced RPC frames, the load of SFCBs-RPC frame beam continues to increase with the increase of deformation after the yielding of SFCBs, demonstrating good bearing capacity and ductility. Furthermore, the deformation and crack width of RPC frame beams are obviously lower than those of ordinary concrete frame beams, indicating the excellent deformation control and crack resistance ability of RPC beams. In addition, formulae for flexural stiffness at each stage were derived using the effective moment of inertia method. Taking the design code of reinforced concrete structure for reference and the tensile contribution of steel fibers and the mechanical performance of SFCBs into consideration, and the formulae for crack width of SFCBs-RPC flexural beam were developed. Formulae for the bearing capacity of SFCBs-RPC frame beams were also proposed on the base of simplified materials constitutive models and reasonable basic assumptions. The values predicted by these proposed formulae aligned well with the results tested. The research provides a theoretical support for the design and application of SFCBs-RPC frame beams.
-
Emerging trends in the Circular Economy: Multidimensional perspective in the building sectorThe study is grounded in the Triple Bottom Line theory, which emphasizes three dimensions of accountability: environmental, social, and economic. However, the research on which the study is based argues that developing an effective framework for adopting the Circular Economy (CE) within the building sector requires a balanced consideration across four dimensions - environmental, social and economic, and technical - as the technical dimension plays a crucial role in the advancement of the CE concept. This complements previous research into the understanding of the CE concept in the building sector, further investigating these key dimensions that capture the evolution of CE research. Focusing specifically on the building sector, the research conducted a robust literature review examining the environmental, social, economic, and technical aspects associated with the CE concept . The aim of this was to identify existing barriers and gaps that prevent the successful adoption of a CE in the building sector. Insights derived from the literature review will then serve as the foundation for a new and comprehensive circular framework appropriate for the building sector. The research and study together thus underscore the importance of a four-dimensional, balanced framework for effectively implementing CE principles within the building sector.
-
Solid biomass chain from production to utilization in UKBioenergy stands as the primary contributor within the realm of global renewables, offering energy security to a multitude of individuals while also fostering growth in rural areas. The emergence of fuel pellets derived from diverse feedstocks has brought forth both prospects and obstacles for current technologies. This article delivers an up-to-date examination of the production and application of fuel pellets sourced from biomass. The upcoming discourse will explore the various aspects, both positive and negative, of the production and utilization of fuel pellets obtained from biomass, with a specific focus on the circumstances in the United Kingdom (UK). Through acquiring a thorough understanding of the manufacturing procedures of fuel pellets, coupled with a detailed examination of their benefits and drawbacks, the feasibility of utilizing biomass can be greatly improved, consequently leading to a significant contribution to the progression of a sustainable bioenergy framework.
-
High-durability, low-carbon, and low-cost nano-engineered concrete for marine concrete infrastructuresTraditional concrete fulfills the mechanical requirements for marine infrastructures but lacks durability. This study employed nano-engineering techniques to address the durability challenges in marine concrete infrastructures by enhancing the chloride ions penetration resistance of low- and medium-strength concrete to be comparable to that of high-strength concrete without increasing cement dosage. Meanwhile, nano-engineered concrete is also expected to reduce the cost and CO2 emissions of concrete structures over the life cycle. For this purpose, the effect and mechanisms of nanofillers on the durability and microstructures of concrete were investigated. Moreover, CO2 emission, cost, and sustainability of nano-engineered concrete were evaluated. The results indicated that a small content of nanofillers remarkably inhibited the penetration of chloride ions into concrete, without increasing cement content. The chloride ions diffusion coefficient of concrete with nanofillers is as low as 3.9010-12 m/s, representing a reduction of 62.8% compared to blank concrete. Moreover, nanofillers effectively refine the concrete microstructure by inducing hydration products into short rods, blocks, and lamellae. The thickness of the interfacial transition zones (ITZs) between cement mortar and gravel as well as cement paste and river sand decreases by 40.7%-55.9%/36.1%-47.4%, respectively, while the porosity of ITZs decreases by 8.7%-17.8%, after adding nanofillers. In addition, the cost and CO2 emission of nano-engineered concrete during production are reduced by 18.1%-27.8% and 14.4%-22.2%, respectively, compared to traditional concrete. These findings demonstrate that nano-engineered concrete can serve as a viable construction material with reasonable strength, high durability, low carbon footprint, and low cost for marine concrete infrastructures.
-
Technical Advancements Toward RIS-Assisted NTN-Based THz Communication for 6G and BeyondThe world is experiencing an explosion in demand for ultra-high data rates with far greater expectations in the next few years. These expectations, given the bandwidth-demanding applications such as augmented and virtual reality and other beyond-5G applications, motivate the exploration of higher-frequency communication in the terahertz (THz) bands. However, THz communication is faced with many technical challenges, primarily due to the high susceptibility to blockages that limit its applications. Here, reconfigurable intelligent surfaces (RIS) provide alternative paths to circumvent such blockage effects and ensure reliable, spectral, and energy-efficient communication, thus advancing the THz-RIS technology concept. However, the ambitious targets of ubiquitous and global connectivity can only be satisfied by many technologies extending to multiple domains, from terrestrial networks to non-terrestrial network (NTN) domains. The use of airborne and spaceborne networks is considered a potential solution for addressing these challenges due to their dynamism, coverage, and ability to leverage their altitude for achieving line-of-sight communication for enhanced signal quality and network performance. Therefore, unmanned aerial vehicles, high-altitude platform stations, and satellites are poised to use flying THz-based RISs to improve air-to-ground and space-to-ground communication reliability while exploiting novel RIS architectures, techniques and enablers to address the issues regarding the propagation conditions, hardware limitations, network complexity and system performance. The aim in this paper is to present the discussion and a survey on the technical advances on THz-RIS NTNs, in addition to outlining potential applications, architectural variants, influencing properties, as well as its prospects, associated challenges, open issues and future directions towards high-data rate THz-RIS NTN communication for 6G and beyond.
-
The Evolution of Biometric Authentication: A Deep Dive Into Multi-Modal Facial Recognition: A Review Case StudyThis survey provides an insightful overview of recent advancements in facial recognition technology, mainly focusing on multi-modal face recognition and its applications in security biometrics and identity verification. Central to this study is the Sejong Face Database, among other prominent datasets, which facilitates the exploration of intricate aspects of facial recognition, including hidden and heterogeneous face recognition, cross-modality analysis, and thermal-visible face recognition. This paper delves into the challenges of accurately identifying faces under various conditions and disguises, emphasising its significance in security systems and sensitive sectors like banking. The survey highlights novel contributions such as using Generative Adversarial Networks (GANs) to generate synthetic disguised faces, Convolutional Neural Networks (CNNs) for feature extractions, and Fuzzy Extractors to integrate biometric verification with cryptographic security. The paper also discusses the impact of quantum computing on encryption techniques and the potential of post-quantum cryptographic methods to secure biometric systems. This survey is a critical resource for understanding current research and prospects in biometric authentication, balancing technological advancements with ethical and privacy concerns in an increasingly digital society.
-
Stochastic Expansion planning Model for a coordinated Natural gas and Electricity Networks Coupled with Gas-fired Generators, Power-to-Gas Facilities and Renewable PowerThis paper presents a stochastic expansion planning model for coordinated natural gas and electricity networks, incorporating gas-fired generators, Power-to-Gas facilities, and renewable power sources. The primary objective is to minimize the total cost over the planning horizon, addressing the significant interdependencies between these networks which, if planned independently, can lead to higher overall costs. The originality of this work lies in its comprehensive integration of both systems, leveraging their synergies to optimize infrastructure investment and operational efficiency. Methodologically, the model employs mixed integer linear programming (MILP) within the General Algebraic Modelling System (GAMS), using a Scenario Tree concept to account for the stochastic nature of renewable energy sources (RESs) and load variations. Data from an adapted twenty-node Belgium gas network and a sixteen-bus UK electricity distribution system were utilized. Results demonstrate substantial cost savings and improved system performance with the integrated approach, validating the model's effectiveness.
-
Preparation of flexible polymer sensor material by Spatial Confining Forced Network Assembly Micro Injection MoldingThe development of high-performance flexible pressure-sensing materials necessitates the simultaneous achievement of exceptional flexibility, conductivity, and alignment of micro-nano structures with the mechanical response characteristics inherent to these materials. In this study, we propose a novel method for preparing flexible microneedles as a pressure-sensitive sensor array. Firstly, we obtain conductive composite particles through extrusion granulation, which consists of a compact conductive network with micron-scale filler as the skeleton and nano-filler filling in the gaps within the network. Moreover, by utilizing the ‘volume exclusion’ effect of the microneedle array on the micron-scale filler during injection molding, nanofillers dominate in entering the microneedle. As a result, our molded product exhibits high flexibility and moderate conductivity in its pressure-sensitive area, thereby providing ultra-high-pressure resistance along with desired response characteristics and sensitivity for sensors. Additionally, due to synergistic effects between microscale fillers and nano-fillers in non-pressure sensitive bases, a compact conductive network is formed that imparts sufficient conductivity to sensor materials. The method yields sensors with excellent repeatability, high dimensional accuracy, and good consistency, effectively addressing core application challenges of flexible sensors. The microstructure array flexible sensor fabricated using high-precision injection molding technology offers high efficiency, low cost, and scalability for mass production. Furthermore, the sensitivity of sensors produced by this method is significantly higher—26.6% greater than those made using traditional methods—with a sensitivity as high as 4.71kPa -1 .
-
Shear behavior of FRP-UHPC composite beams enhanced by FRP shear key: Experimental study and theoretical analysisTo investigate the shear behavior of FRP (fiber reinforced polymers)-UHPC (ultra-high performance concrete) composite beams, four-point bending tests were conducted on seven FRP-UHPC specimens and two FRP-NSC (normal strength concrete) specimens, having different width and depth of concrete flange as well as FRP shear key (FSK) spacing. The slip between FRP profiles and concrete flange was controlled by employing FSK and epoxy resin bonded hybrid connection. The failure pattern, load-deflection/strain curves, and sliding response of composite beams were analyzed to study the influence of concrete type, FSK spacing, width and thickness of concrete slab. The results indicate that FRP-UHPC composite beams exhibited shear failure, while FRP-NSC composite beams experienced bending-shear failure. The composite beams demonstrated shear-lag effect, which became more pronounced with the increasing of the concrete slab width. The use of UHPC, reducing FSK spacing, and increasing the size of cross-section of concrete flange can effectively enhance the shear performance and reduce interface sliding. Formulae were developed to predict the shear capacity and deflection, considering shear deformation. The results predicted by the formulae developed match well with the experimental results.
-
Shear performance of poplar LVL beams with a hole in bending-shear spansTo investigate the shear performance of poplar laminated veneer lumber (LVL) beams with holes in bending-shear spans, six specimens were designed and tested by four-point bending tests. Among these, five specimens were provided with a single hole of varying diameter-to-height ratio in the bending-shear span and two of these beams were also reinforced with circumferential carbon fiber reinforced polymer (CFRP) wrap layers. Furthermore, a 3D finite element models for poplar LVL beams with a hole were established, based on the extended finite element method (XFEM) using ABAQUS software. The validated model was utilized to conduct parametric studies on the diameter-to-height ratio, the hole shape, and the vertical eccentricity ratio. A simplified theoretical analysis for predicting the cracking and ultimate loads for LVL beam with a hole was also proposed. The results indicated that beams without a hole failed due to bending, characterized by mid-span tension cracks, whereas beams with a hole exhibited shear failure along the beam's grain direction due to stress concentration around the holes. The maximum normal tensile strain perpendicular to grain around the hole had an angle of 45° or 225° relative to the beam's longitudinal axis, consistent with the crack initiation angle. As the diameter-to-height ratio increased, the cracking and ultimate loads of beams with a hole decreased, indicating more brittle failure characteristics. The circular hole beam showed significant improvements in cracking and ultimate loads compared with the square hole beam with side length equal to the diameter of the circular hole. When the hole center's vertical eccentricity was in the compression zone, an increase in vertical eccentricity led to enhancements in both the cracking load and ultimate loads. Wrapping the beam with CFRP sheet around the hole effectively mitigated crack propagation, enhancing the load-bearing capacity of beams. The simplified formulas provided accurate prediction for the ultimate load, but highly overestimated the cracking and ultimate loads for poplar LVL beams with a hole. The research findings can be provided as a technical support for the design and application of LVL beams with holes.
-
A review on the potential application of ultra-high performance concrete in offshore wind towers: Insights into material properties, mechanisms, and modelsUltra-high performance concrete (UHPC), characterized by its high strength and toughness as well as durability, provides a promising solution for the construction of offshore wind towers (OWTs). This paper comprehensively reviews the durability and the dynamic mechanical properties of UHPC for OWTs under the impacts of the marine environment. Furthermore, the modifying effects of additives, including supplementary cementitious materials (SCMs) and reinforcing fibers, as well as nanofillers on UHPC are explored. Overall, UHPC possesses a dense microstructure that impedes the intrusion of harmful substances, and owing to the incorporation of additives, UHPC exhibits outstanding dynamic mechanical properties, making it an ideal material for applications in OWTs subjected to vibration fatigue and dynamic impact loads. Incorporating SCMs into UHPC can improve the durability and environmental benefits while maintaining similar dynamic mechanical properties concurrently. Nanofillers can serve as a beneficial supplement to steel fibers providing improved durability and dynamic mechanical properties by endowing UHPC dense microstructure and high system energy. Various models of marine environmental and loading actions on UHPC, examining ion transport, matrix degradation, and constitutive models, are concluded to gain insight into the underlying destructive mechanisms. These underlying mechanisms and the theoretical models further deepen the understanding of the service performance of UHPC in marine environments, thus providing the design guidance for the potential applications of UHPC in OWTs.
-
Natural language processing-driven framework for the early detection of language and cognitive declineNatural Language Processing (NLP) technology has the potential to provide a non-invasive, cost-effective method using a timely intervention for detecting early-stage language and cognitive decline in individuals concerned about their memory. The proposed pre-screening language and cognition assessment model (PST-LCAM) is based on the functional linguistic model Role and Reference Grammar (RRG) to analyse and represent the structure and meaning of utterances, via a set of language production and cognition parameters. The model is trained on a DementiaBank dataset with markers of cognitive decline aligned to the global deterioration scale (GDS). A hybrid approach of qualitative linguistic analysis and assessment is applied, which includes the mapping of participants´ tasks of speech utterances and words to RRG phenomena. It uses a metric-based scoring with resulting quantitative scores and qualitative indicators as pre-screening results. This model is to be deployed in a user-centred conversational assessment platform.
-
Experiment and numerical modelling of a demountable steel connection system for reuseCurrently, steel reuse is only a marginal practice. To facilitate deconstruction and efficient reuse of steel components, an innovative connection system was proposed. This system adopts a ‘Block Shear Connector (BSC)’ that allows beam length to be standardised and suitable for a wide range of different sizes of the supporting members within the same planning grid. This paper presents the experimental and numerical studies of a beam-to-beam connection using BSCs. The BSC used was made from a standard universal HE / UC section and was bolted to the beams by using partial depth end plates. The experimental results provided the shear resistance, momentrotation, failure behaviour, demountability and reusability of the steel components. Further numerical simulation conducted investigated the effect of some key parameters (steel strength, thickness of BSC web, thickness of BSC flange, initial bolt stress) on the behaviour of the connections. The results obtained highlighted the demountability of this innovative bolted connection system and the reusability of structural components.
-
An NLP-based framework for early identification of design reliability issues from heterogeneous automotive lifecycle dataNatural Language Processing is increasingly used in different areas of design and product development with varied objectives, from enhancing productivity to embedding resilience into systems. In this paper, we introduce a framework that draws on NLP algorithms and expert knowledge for the automotive engineering domain, to extract actionable insight for system reliability improvement from data available from the operational phase of the system. Specifically, we are looking at the systematic exploration and exploitation of automotive heterogeneous data sources, including both closed-source (such as warranty records) and open-source (e.g., social networks, chatrooms, recall systems) data, to extract and classify information about faults, with predictive capability for early detection of issues. We present a preliminary NLP-based framework for enhancing system knowledge representation to increase the effectiveness and robustness of information extraction from data, and discuss the temporal alignment of data sources and insight to improve prediction ability. We demonstrate the effectiveness of the proposed framework using real-world automotive data in a recall study for a vehicle lighting system and a particular manufacturer: four recall campaigns were identified leading to corrective actions by the warranty experts.
-
Cavitation in die drawn poly(4-methyl-1-pentene) during second-stage tensile deformationPre-oriented poly (4-methyl-1-pentene) samples were prepared by the die drawing process. The stress whitening phenomenon induced by cavities in the different die drawn P4M1P samples during the second-stage tensile deformation was investigated at temperatures below and above Tg. At 30 °C and 50 °C, the cavitation process near yield point is influenced by the fraction of unoriented crystalline phase in pre-oriented samples. Cavities originate from the fracture of the crystalline skeleton at small strains were observed in the sample with a high fraction of unoriented crystalline phase. At high deformation temperature, the small strain cavities were suppressed and the cavitation processes in all die drawn samples are due to the failure of the highly oriented fibrillar network caused by the breaking of the load-bearing interfibrillar/microfibrillar tie molecule chains.
-
Deformation Temperature Dependency of Microstructure Evolution in Die-Drawn iPP/UHMWPE BlendsUltrahigh molecular weight polyethylene (UHMWPE) is one of the most promising polyolefins, but its processability and consequently applications are limited by its high melt viscosity. An effective method to improve the processability is to introduce another polymer component. Yet it is challenging to deform the sample if the components are not compatible with each other. In this work, we blended the UHMWPE with isotactic polypropylene (iPP) and successfully processed the iPP/UHMWPE samples via die-drawing at temperatures below, near, and above the melting temperature of UHMWPE. It was found that the melting behavior of the die-drawn samples was determined by the deformation temperature. The molecular chain orientation slightly decreased, while the long periods first increased and then decreased with increasing deformation temperature. Three melting peaks observed in the samples deformed at 130 and 140 °C originated from the melting of cooling-induced UHMWPE crystallites, deformation-induced fibrillar UHMWPE crystallites, and deformation-induced fibrillar iPP crystallites, respectively. The melting peak of deformation-induced fibrillar UHMWPE crystallites could not be observed in the sample deformed at 150 °C because it is unlikely for UHMWPE chains to crystallize at such a high temperature. This sample also has the lowest melting point since the UHMWPE lamellae formed during deformation could serve as nucleation sites in the other two samples.
-
Control of extrudate swell and instabilities using a rotating roller dieThermoplastics extruded from dies will always swell and above a critical flow rate display instabilities (sharkskin, stick-spurt or gross melt fracture). Prior research has shown that the best way to suppress these instabilities is to reduce the entry converging angle using a smooth convergence and induce permanent wall slip. In this research we go a step further by allowing the walls to move using a rotating roller die. Thus both extrudate swell and flow instabilities become controllable. This paper presents data to support this claim. The practical benefits are important as stable operation at higher flow rates become permissible. Also, by providing extra control variables, this device becomes a useful tool to help unravel the causes of the various instabilities that arise in polymer melt die extrusion. A first from this research, using this roller die geometry we were able to tease out surface roughness instability with polystyrene hitherto not reported.
-
Evaluation of carbon calculators in construction industry: A parametric studyThe construction industry has high energy demand and emissions, and its devasting impact negatively contributes to climate emergency and climate change. A review of government, professional and scientific literature has recommended multiple strategies, including renewable energy adoptions, alternative non-carbon energy sources, circular economy, net zero carbon policies and calculators. The use of carbon calculators as a tool to estimate carbon emissions has become instrumental in guiding construction professionals in selecting appropriate ‘low carbon’ materials for projects. However, the influx of carbon calculators is very important but creates problems for professionals regarding their effectiveness. Therefore, this study compares two popular carbon calculators (One Click LCA Planetary and IStructE) on a building design to ascertain their efficacy. The criteria for the comparison included formats of calculators, commercialisation of calculators, customisation of data, sustainability certifications, data sources, data entry parameters and results/outputs. The findings show a ‘mixed’ outcome regarding the strengths and weaknesses of the calculators. These criteria are key for becoming the basis of selecting an appropriate carbon calculator for analysis. The discussion shows that data for the carbon calculators from countries considered upper-middle-income and/or below are lacking; carbon calculators should be easier to use; the interoperability of carbon calculators with other digital tools is key for not just making the use of the tools attractive but makes it easier to reduce non-value activities in the construction project.
-
Mapping the barriers of big data process in construction: The perspective of construction professionalsThis study identifies, maps and thematizes the barriers to the big data process in the construction industry from the perspective of construction professionals. Australian construction professionals with varying experiences in the big data process were interviewed. Qualitative data analysis identified forty barriers in the big data process and five themes: people, knowledge, technology, data, and environment. The barriers were further mapped, with some transcending more than one stage in the big data process. Many of the barriers have not been empirically identified in previous studies. By implication, mapping the barriers across the big data process enables professionals/construction firms to visualize the potential lapses before and/or during implementation. Therefore, the study offers professionals/construction firms strategic insights and operational perspectives for planning and deploying big data processes.
