20505 research outputs found
Sort by
Finding a greener, cost-effective and colour-based partial or complete replacement to White Portland Cement for cast stone production using TOPSIS
Get PDFAs per recent research, the use of White Portland Cement (WPC) in the production of cast stone results in significant carbon emissions. This study aims to identify alternatives to WPC that have lower carbon emissions and are cost-effective. A literature review was performed, and data were gathered on WPC and its alternatives. Based on the literature review, five alternatives were identified. An investigation was conducted to determine the most suitable replacement for WPC based on four criteria. Automatically weighted TOPSIS which is a Multi-Criteria Decision Analysis (MCDA) was used to identify the optimal substitute for WPC. The results of the analysis were used to make a final recommendation. Overall, this study provides valuable insights into the potential substitutes for WPC in the production of cast stone, which could help to reduce carbon emissions and promote greater sustainability in the construction industry.SDM-2023 10th International Conference on Sustainable Design and ManufacturingSustainable Design and Manufacturing 202
Design and simulation of eVTOL aircraft Thermal Management System
Get PDFVertical Take-off and Landing (VTOL) aircraft with hybrid or fully-electric propulsion systems are becoming popular for Urban Air Mobility (UAM) applications. However, they face challenges such as limited power and energy density, stringent operating temperature constraints, and the generation of low-grade waste heat. These issues emphasize the need for effective Thermal Management Systems (TMS) design. In light of the above, this paper aims to design the TMS for a parallel hybrid electric XV-15 aircraft, a widely known civil tiltrotor concept. The TMS is integrated into the aircraft system to assess its impact on energy efficiency and emissions at both aircraft and mission levels. This study considers current state of the art technology and expected advancements over the next two decades to identify the benefits of electrification. In the designed TMS, liquid cooling cold plates serve as the main heat acquisition and cooling system for each electric component. An air-coolant heat exchanger is also incorporated to dissipate the accumulated heat load. The study conducts a comparative analysis to determine the optimal TMS design point. It involves a comparison between two design scenarios: one focused on the cruise condition, which constitutes a significant portion of the flight mission, and another designed specifically for peak heat load conditions. This ensures a holistic evaluation of the TMS's performance across various flight phases, balancing efficiency and resilience to peak demands. Finally, the energy efficiency and emission penalty associated with the TMS integration are quantified and discussed in the study.Journal of Engineering for Gas Turbines and Powe
Blockchain-based traceability framework for agri-food supply chain: a proof-of-concept
No full textThis paper outlines the integration of blockchain technology (BCT) into agri-food supply chains (AFSC) and provides a comprehensive framework for organisations interested in adopting Blockchain (BC)-enabled traceability. Collaborating with an agri-food-based use-case organisation and a technology provider, the authors present a use case for the deployment of BCT in honey and coriander powder supply chains. The proof-of-concept (POC) for the BC-based traceability framework was developed with inputs from both the use-case organisation and the technology provider. The findings suggest that the demand for improved traceability may incentivise adoption within specific operations of the agri-food business despite existing challenges. Additionally, the pilot study introduces a cost framework, delving into the developmental and operational costs associated with the developed POC. Furthermore, the paper discusses stakeholders’ perspectives by exploring challenges faced during the implementation phase and highlighting the perceived benefits of adoption. Positioned at the intersection of the agri-food sector, digitalisation, and the growing demand for information and product integrity, this research emphasises the unique potential of BCT. In practical terms, this study can serve as a valuable step-by-step guide for managers seeking to understand the process of BCT implementation in AFSC, offering insights into the operational and strategic aspects of adopting BCT.Ministry of Food Processing Industries (Govt. of India), Grant Number: Q-11/13/2021-R&D.Operations Management Researc
Wind speed probabilistic forecast based wind turbine selection and siting for urban environment
Get PDFWind energy being a free source of energy is becoming popular over the past decades and is being studied extensively. Integration of wind turbines is now being expanded to urban and offshore settings in contrast to the conventional wind farms in relatively open areas. The direct installation of wind turbines poses a potential risk, as it may result in financial losses in scenarios characterized by inadequate wind resource availability. Therefore, wind energy availability analysis in such urban environments is a necessity. This research paper presents an in‐depth investigation conducted to predict the exploitable wind energy at four distinct locations within Nottingham, United Kingdom. Subsequently, the most suitable location, Clifton Campus at Nottingham Trent University, is identified where a comprehensive comparative analysis of power generation from eleven different wind turbine models is performed. The findings derived from this analysis suggest that the QR6 wind turbine emerges as the optimal choice for subsequent experimental investigations to be conducted in partnership with Nottingham Trent University. Furthermore, this study explores the selection of an appropriate probability density function for assessing wind potential considering seven different distributions namely, Gamma, Weibull, Rayleigh, Log‐normal, Genextreme, Gumbel, and Normal. Ultimately, the Weibull probability distribution is selected, and various methodologies are employed to estimate its parameters, which are then ranked using statistical assessments.The project has received funding from the European Union’sHorizon 2020 research and innovation programme underthe Marie Skłodowska-Curie grant agreement No 860101 –zEPHYR and has been supported by CI TASK (Gdansk,Poland).IET Renewable Power Generatio
An aircraft-manipulator system for virtual flight testing of longitudinal flight dynamics
Get PDFA virtual flight test is the process of flying an aircraft model inside a wind tunnel in a manner that replicates free-flight. In this paper, a 3-DOF aircraft-manipulator system is proposed that can be used for longitudinal dynamics virtual flight tests. The system consists of a two rotational degrees-of-freedom manipulator arm with an aircraft wind tunnel model attached to the third joint. This aircraft-manipulator system is constrained to operate for only the longitudinal motion of the aircraft. Thus, the manipulator controls the surge and heave of the aircraft whilst the pitch is free to rotate and can be actively controlled by means of an all-moving tailplane of the aircraft if required. In this initial study, a flight dynamics model of the aircraft is used to obtain dynamic response trajectories of the aircraft in free-flight. A model of the coupled aircraft-manipulator system developed using the Euler method is presented, and PID controllers are used to control the manipulator so that the aircraft follows the free-flight trajectory (with respect to the air). The inverse kinematics are used to produce the reference joint angles for the manipulator. The system is simulated in MATLAB/Simulink and a virtual flight test trajectory is compared with a free-flight test trajectory, demonstrating the potential of the proposed system for virtual flight tests.This research is partly funded by the Tertiary Educational Trust Fund (TETFUND) Nigeria, grant number TETF/ES/UNIV/OGUNSTATE/TSAS/2020.Robotic
A mixed-elastohydrodynamic lubrication model of a capped-T-ring seal with a sectioned multi-material film thickness in landing gear shock absorber applications
Get PDFNumerical investigations of capped T-ring (CTR) seals performance in reciprocating motion for landing gear shock absorber applications are presented. A lubrication model using the Elastohydrodynamic lubrication theory and deformation mechanics is developed in a multi-material contact zone, and a procedure for coupling fluid and deformation mechanics is introduced. By conducting Finite Element Method (FEM) simulations, the static contact pressure is obtained, which subsequently is used within the model developed herein consisting of a modified Reynolds equation and an asperity contact model, to calculate the fluid film pressure, and the deformation of the fluid channel is determined using an elastic deformation model applied to a multi-component multi-mechanical property channel. These computational results are used for estimations of the seal leakage and friction under various conditions. In addition, the influence of asperity orientation is compared with other parameters, such as sealing pressure and piston velocity. A correlation between asperity orientation and leakage was found, and a general trend of reduced leakage with longitudinally oriented asperities was established.This work was conducted under the ATI/Innovate UK (Grant No. 263261) Project: Future Landing Gear 2, with Airbus UK as Industrial Lead. The authors also acknowledge funding from EPSRC (Grant No. 2625870).Fluid
A model development approach based on point cloud reconstruction and mapping texture enhancement
Get PDFTo address the challenge of rapid geometric model development in the digital twin industry, this paper presents a comprehensive pipeline for constructing 3D models from images using monocular vision imaging principles. Firstly, a structure-from-motion (SFM) algorithm generates a 3D point cloud from photographs. The feature detection methods scale-invariant feature transform (SIFT), speeded-up robust features (SURF), and KAZE are compared across six datasets, with SIFT proving the most effective (matching rate higher than 0.12). Using K-nearest-neighbor matching and random sample consensus (RANSAC), refined feature point matching and 3D spatial representation are achieved via antipodal geometry. Then, the Poisson surface reconstruction algorithm converts the point cloud into a mesh model. Additionally, texture images are enhanced by leveraging a visual geometry group (VGG) network-based deep learning approach. Content images from a dataset provide geometric contours via higher-level VGG layers, while textures from style images are extracted using the lower-level layers. These are fused to create texture-transferred images, where the image quality assessment (IQA) metrics SSIM and PSNR are used to evaluate texture-enhanced images. Finally, texture mapping integrates the enhanced textures with the mesh model, improving the scene representation with enhanced texture. The method presented in this paper surpassed a LiDAR-based reconstruction approach by 20% in terms of point cloud density and number of model facets, while the hardware cost was only 1% of that associated with LiDAR.Big Data and Cognitive Computin
Common institutional ownership and corporate carbon emissions
Get PDFThere has been a growing interest in comparative work exploring when and why firms embark on green paths. It has been concluded that in national contexts where inter‐firm ties are stronger, progress has been stronger. In turn, this raises questions about the impact of inter‐firm ties within, rather than between, national contexts, and in settings where progress towards renewables has been uneven and contested. Accordingly, we explore how common institutional ownership may foster collaboration among firms within the same industry against climate change. Using a sample of US‐listed firms from 2006 to 2019, we obtain robust evidence that firms with industrial peers that are owned by the same institutional investors have lower carbon emissions. In addition, we find that a threshold exists for which the impact on carbon emissions holds only when firms are commonly connected with a substantial number of peers. The existence of this threshold suggests potential free‐riding issues and highlights the beneficial role of investors in promoting cross‐industry collaboration. Overall, our results highlight the role played by institutional investors in tackling climate issues, with important implications for both climate‐ and antitrust‐related regulations.National Natural Science Foundation of ChinaBritish Journal of Managemen
‘Shifting gears ain't easy’: Disciplinary resistances to perspective shifts in soil science and how to move forward
Get PDFOver the last decade, the fact that novel perspectives on various aspects of soils have remained strongly controversial long after they emerged, without any kind of consensus being reached about them, raises question about the underlying reasons for this phenomenon. The on‐going debate on the usefulness of aggregates to describe the functions of soils illustrates some of the key aspects of that question. Similar debates on other soil‐related issues also appear stalled, or have been for a long time and are only now moving forward. This might suggest a fundamental aversion to change, which when it gets overcome, only does so slowly. However, at the same time, somewhat surprisingly, researchers appear willing to quickly seize opportunities provided by new idea or novel perspectives on other topics. In that context, the objective of the present article is to analyse in detail what may cause such contrasting reactions to novelty. We consider, then ultimately dismiss, explanations based on how strongly or not novel perspectives have been actively promoted, on how access to suitable technology may impede or only slow down perspective shifts and on whether a recent theory of the ‘slowed canonical progress in large fields of science’ applies to the relatively small soil science community. Then, taking soil aggregates as a case in point, we come to realize that it is the extent to which a novel perspective mandates an interdisciplinary approach that determines whether or not it is adopted quickly. From that standpoint, we envisage a number of practical actions that could be taken to facilitate in the future the emergence in soil science of interdisciplinary research efforts, which we argue are absolutely essential to successfully tackle the enormous complexity of soils and to come up with satisfactory answers to the daunting environmental and food security problems we currently face in their management.European Journal of Soil Scienc
PRobust: a percolation-based robustness optimization model for underwater acoustic sensor networks
Get PDFIn Underwater Acoustic Sensor Networks (UASNs), the robustness of network is greatly affected by complex marine environments when implementing multi-hop data transmission. Factors such as the underwater acoustic channel and dynamic topological changes induced by multi-layered oceanic vortices exacerbate this influence. However, there is currently a research gap in the specific area of robustness optimization for UASNs. Existing studies on robustness optimization are unsuitable for UASNs as they neglect the considerations of the marine environment and node characteristics (e.g., residual energy). In this work, we propose PRobust, a percolation-based robustness optimization model for UASNs. PRobust consists of two distinct phases: percolation modeling and bottleneck optimization. In the percolation modeling phase, we incorporate both node and edge features, considering the physical and topological properties, and introduce a novel approach for calculating link quality. In the bottleneck optimization phase, we devise a graph theory-based method to identify bottlenecks, leveraging the flow information recorded by nodes to improve the accuracy of bottleneck discovery. Moreover, we integrated time slots and a current movement model into the proposed model, allowing its applicability to dynamically changing UASNs. Extensive simulation results indicate that, compared to existing methods, PRobust significantly enhances network robustness and performance with the same overhead after bottleneck optimization.IEEE Transactions on Network and Service Managemen