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A 3D Elastoplastic Constitutive Model Considering Progressive Damage Behavior for Thermoplastic Composites of T700/PEEK
Get PDFData Availability Statement:
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.Due to their excellent mechanical properties, the carbon fiber-reinforced polymer composites (CFRPs) of thermoplastic resins are widely used, and an accurate constitutive model plays a pivotal role in structural design and service safety. A two-parameter three-dimensional (3D) plastic potential was obtained by considering both the deviatoric deformation and the dilatation deformation associated with hydrostatic stress. The Langmuir function was first adopted to model the plastic hardening behavior of composites. The two-parameter 3D plastic potential, connected to the Langmuir function of plastic hardening, was thus proposed to model the constitutive behavior of the CFRPs of thermoplastic resins. Also, T700/PEEK specimens with different off-axis angles were subjected to tensile loading to obtain the corresponding fracture surface angles of specimens and the load–displacement curves. The two unknown plastic parameters in the proposed 3D plastic potential were obtained by using the quasi-Newton algorithm programmed in MATLAB, and the unknown hardening parameters in the Langmuir function were determined by fitting the effective stress-plastic strain curve in different off-axis angles. Meanwhile, the user material subroutine VUMAT, following the proposed constitutive model, was developed in terms of the maximum stress criterion for fiber failure and the LaRC05 criterion for matrix failure to simulate the 3D elastoplastic damage behavior of T700/PEEK. Finally, comparisons between the experimental tests and the numerical analysis were made, and a fairly good agreement was found, which validated the correctness of the proposed constitutive model in this work.Civil Aviation Education and Talent Project of China (MHJY2023012); Project of Science and Technology Department of Sichuan Province (23RCYJ0065)
Improving the Efficiency of Electric Vehicles: Advancements in Hybrid Energy Storage Systems
Get PDFData Availability Statement: The data that support the findings of this study are available from the corresponding authors upon reasonable request.Electric vehicles (EVs) encounter substantial obstacles in effectively managing energy, particularly when faced with varied driving circumstances and surrounding factors. This study aims to evaluate the performance of three different control systems in a fully operational hybrid energy storage system (HESS) installed in the Nissan Leaf. The objective is to improve the performance of EVs by focusing on optimising energy management in response to different global environmental and driving circumstances. This study utilises an analytical strategy by developing a distinct energy management system model using MATLAB/Simulink. This model is specifically designed for optimising the integration and control of batteries and supercapacitors (SCs) in a fully active HESS. This model mimics the performance of the controllers under three different driving cycles—Artemis rural, Artemis motorway, and US06. The findings demonstrate notable progress in managing the battery state of charge (SOC) and the system’s responsiveness, especially when employing the radial basis function (RBF) controller. This study emphasises the capacity of HESSs to enhance the effectiveness and durability of EVs, therefore promoting wider acceptance and progress in electric transportation technology.This research is funded by the National Natural Science Foundation of China (62206062) and the EPSRC Doctoral Training Programme
DAGCN: Distance-based and Aspect-oriented Graph Convolutional Network for Aspect-based Sentiment Analysis
Get PDFAspect-based sentiment analysis (ABSA) is a task that aims to determine the sentiment polarity of aspects by identifying opinion words. Recent advancements have predominantly been rooted either in semantic or syntactic methods. However, both of them tend to interference from local factors such as irrelevant words and edges, hindering the precise identification of opinion words. In this paper, we present Distance-based and Aspect-oriented Graph Convolutional Network (DAGCN) to address the aforementioned issue. Firstly, we introduce the Distance-based Syntactic Weight (DSW). It focuses on the local scope of aspects in the pruned dependency trees, thereby reducing the candidate pool of opinion words. Additionally, we propose Aspect-Fusion Attention (AF) to further filter opinion words within the local context and consider cases where opinion words are distant from the aspect. With the combination of DSW and AF, we achieve precise identification of corresponding opinion words. Extensive experiments on three public datasets demonstrate that the proposed model outperforms state-of-the-art models and verify the effectiveness of the proposed architecture.This work was supported in part by the National Natural Science Foundation of China under Grant 62372300, Grant 62302306, and Grant 62201350, and in part by the National Key Research and Development Program of China under Grant No.2022YFB4501704, and in part by the Research Base of Online Education for Shanghai
Middle and Primary Schools
Filtering Efficiency and Design Properties of Medical- and Non-Medical-Grade Face Masks: A Multiscale Modeling Approach
Get PDFData Availability Statement: The data presented in this study are available on request from the corresponding author due to privacy and ethical restrictions.Approved medical face masks have been shown to prevent the spread of respiratory droplets associated with coronavirus transmission in specific settings. The primary goal of this study was to develop a new strategy to assess the filtering and transmissibility properties of medical- and non-medical-grade face masks. In this study, we designed and assessed the filtering efficiency of particles through six different masks with a diverse set of fabrics, textures (woven and non-woven), fiber diameters, and porosity. The filtering and transmissibility properties of face mask layers individually and in combination have been assessed using mathematical analyses and new experimental data. The latter provided velocity profiles and filtration efficiencies for which the data were shown to be predictable. The filtration efficacy and pressure drop across each fabric have been tested using an aerosol particle spray and scanning electron microscopy. To assess clinical significance, the temperature and humidity of the masks were tested on a group of healthy volunteers spanning various age ranges (9–79 years old), utilizing an embedded temperature sensor disc. Also, a mask filter model was developed using fluid dynamic simulations (Solidworks Flow) to evaluate the aerodynamic dispersion of respiratory droplets. Overall, the FFP2 and FFP3 masks demonstrated the highest filtration efficiencies, each exceeding 90%, a feature of multi-layered masks that is consistent with simulations demonstrating higher filtering efficiencies for small particles (<5 µm). The velocity and temperature simulations of all six masks revealed a low air velocity (~1 m/s) inside the mask and a temperature variation of approximately 3 °C during the breathing cycle.No funding was received for conducting this study
Secure Downlink Transmission for Integrated Sensing, Energy, and Communication Systems
Get PDFThis paper proposes an integrated sensing, energy, and communication (ISEAC) system that considers secure communication. In this system, the base station (BS) is serving as one legitimate single-antenna information receiver (IR) whose position is known and multiple single-antenna energy receivers (ERs) that are considered as eavesdroppers whose locations are unknown and need to be detected. First, we propose a framework for designing transmitter beamforming to maximize the system secrecy rate under the energy-harvesting constraint and the sensing constraints. Next, we study the beamforming design of the system under imperfect channel status information (CSI). For the non-convex equations in these two cases, we use semidefinite relaxation (SDR) and Taylor expansion to transform the problem to the convex form. Finally, the simulation results verify the effective performance of the proposed optimal beamforming design.10.13039/501100015013-National Mobile Communications Research Laboratory, Southeast University (Grant Number: 2023D03
Influence of Operation Parameters on Thermohydraulic Performance of Supercritical CO<inf>2</inf> in a Printed Circuit Heat Exchanger
Get PDFData Availability: All data used are in the article but if any additional information is required it can be obtained by contacting the corresponding author.The performance of recuperative printed circuit heat exchangers is critical in supercritical CO2 (sCO2) power generation applications. This article presents a three-dimensional numerical model of sCO2 flowing in a printed circuit heat exchanger and investigates its thermohydraulic performance under different operation conditions. The simulations employ the standard k-ε turbulent model, and consider entrance effects, conjugate heat transfer, real gas thermophysical properties and buoyancy effects. The heat exchanger operation parameters cover mass flux from 254.6 to 1273.2 kg/m2s, inlet temperature 50–150 °C and outlet pressure 100–250 bar on the cold side, and 300–500 °C and 75–150 bar on the hot side. Results show that increasing CO2 mass flux leads to a significantly increased heat transfer coefficient, a slight increase in temperature difference between the hot and cold CO2, as well as larger pressure drop and lower friction factor on both sides. Increasing the cold CO2 pressure, decreasing the cold CO2 temperature, and increasing the hot CO2 temperature result in a higher heat transfer rate of the heat exchanger. Increasing the CO2 temperature on each side causes increased pressure drops on both sides. Increasing the CO2 pressure on each side reduces the pressure drop on each side.The work presented in this article was supported by a number of funders as follows: (i) The Engineering and Physical Sciences Research Council (EPSRC) of the UK under research grants EP/P004636/1—OPTEMIN, and EP/V001795/1—SCOTWOHR; (ii) the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 680599—I-ThERM and Grant Agreement No. 101022831—CO2OLHEAT. The authors would like to acknowledge the financial support received from the funders and industry partners
Moral licence and disbelief: How voters look past political misconduct
Get PDFData availability statement: The datasets generated during and/or analysed during the current study are available from the corresponding author upon reasonable request.How do voters respond to a co-partisan political candidate after hearing about a serious scandal? We apply qualitative content analysis to open-ended text responses collected from survey respondents, focusing on 159 respondents who remain willing to vote for a hypothetical male candidate after learning that allegations of sexual harassment against him were settled out of court. We uncover two main strategies by which respondents explained and justified their willingness to look past the misconduct allegations. The dominant strategy was to extend moral licence to the candidate based on his prior good deeds; a second prominent strategy was to disbelieve and reject the allegations. Our findings offer new insights on why some political candidates and careers appear untroubled by even serious allegations of misconduct, and frames new research avenues on which voters might be more likely to extend moral licence and in what circumstances.Brunel University London [grant number RDF Award LBG178]; Royal Holloway University
Cultural dynamics and tenure trajectories: How auditor tenure and culture influence key audit matters in the GCC
Get PDFPurpose:
This study examines the impact of audit partner tenure on Key Audit Matters (KAM) disclosures within Gulf Cooperation Council (GCC) countries. It explores how Hofstede’s cultural dimensions influence this relationship, elucidating the effect of cultural context on auditing practices.
Design/methodology/approach:
Utilizing a sample of 456 non-financial firms in the GCC from 2016 to 2021, the study employs regression analyses to explore audit partner tenure's influence on KAM disclosures and the moderating effects of Hofstede's dimensions of power distance, individualism, masculinity and uncertainty avoidance. This affords a detailed examination of individual and cultural impacts on audit quality.
Findings:
Results reveal a positive relationship between audit partner tenure and KAM disclosures, suggesting that firm-specific knowledge and industry expertise acquired over a long tenure may enhance auditors' ability to identify and report significant matters. Power distance and uncertainty avoidance amplify this effect, whereas individualism diminishes it. Masculinity does not yield significant results.
Research limitations/implications:
This study underscores the need for auditing standards to reflect the complex interplay of auditor tenure and cultural dynamics in the profession's global landscape.
Originality/value:
This research contributes to the literature on audit quality by highlighting the formative role of individual auditors and cultural characteristics in KAM disclosure practices. It is among the first to quantitatively analyse the intersection of audit partner tenure and culture in the GCC. It provides valuable insights for regulators, practitioners and policymakers seeking to enhance audit practices across diverse cultural environments
Prehospital emergency care for trauma victims in Nepal: a mixed-methods study
Get PDFData-sharing statement: All data requests should be submitted to the corresponding author for consideration. Access to anonymised data may be granted following review.Background:
The prehospital care system in Nepal is poorly developed, with multiple providers, limited co-ordination of services and no national coverage. There is little published evidence reporting the prehospital care of patients with trauma, data which are important to inform the development of the prehospital care system.
Objectives:
In order to understand the challenges of providing prehospital care to trauma patients, the study aimed to explore the burden of trauma presenting to prehospital care providers and the experience of providing care to these patients.
Design:
We used a mixed-method study that included secondary data analysis and qualitative semistructured interviews.
Setting:
Nepal (Kathmandu Valley, Chitwan, Pokhara and Butwal).
Participants:
Staff employed by the Nepal Ambulance Service including ambulance drivers, emergency medical technicians, dispatch officers and service managers.
Data sources:
Data describing callouts by the Nepal Ambulance Service over 1 year. Callout data were anonymised and analysed descriptively. Semistructured interviews were audio-recorded, transcribed, translated and analysed using inductive thematic analysis.
Results:
Of 1408 trauma calls received, 48.4% (n = 682) resulted in prehospital care being provided. The most common mechanism of injury was falls (35.8%), followed by road traffic crashes (19.1%) and the commonest types of injuries were fractures (33.1%) and spinal injuries (10.1%). Mean time from call to arrival at hospital was 48 minutes (range 20 minutes–6 hours). Seventeen staff described factors facilitating effective prehospital care, including having adequate resources, systems and training. Barriers to delivering prehospital care included the expectations and behaviour of patients’ relatives and bystanders, a lack of public awareness of the role and provision of prehospital care, and poor road and traffic conditions.
Limitations:
For some data fields, data were missing, limiting the ability to precisely determine patient needs and response times. The qualitative data may have been subject to responder bias if participants felt uncomfortable reporting something that may have reflected badly on their employer.
Conclusions:
Trauma is a major reason for requesting prehospital care, which can be delivered in less than an hour from receiving a call to arrival at the hospital. Multiple factors impede the effective delivery of care which could be addressed through further development across the prehospital care system.
Future work:
Qualitative research to explore the perceptions and experiences of trauma victims, road users, emergency department staff, police officers, members of organisations involved in prehospital care, firefighters, and policy-makers would complement the findings from this study. Specific issues raised, such as the difficulties experienced when handing over patients between prehospital and hospital care providers, warrant further exploration.This article presents independent research funded by the National Institute for Health and Care Research (NIHR) Global Health Research programme as award number 16/137/49 using UK aid from the UK Government to support global health research
Data sources:
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