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A Review of Recent Advancements in Heat Pump Systems and Developments in Microchannel Heat Exchangers
Get PDFHeating and cooling are the main concerns across a wide range of sectors, including residential buildings, industrial facilities, transportation and commercial enterprises. This being the case, a continuous rise in the cost of energy demands more effective ways to conserve energy. Heat pump (HP) systems provide the one of the best possible solutions to this problem as they offer an economical and energy-efficient system. In this review, HP systems are overviewed as energy-efficient and cost-effective solutions, focusing on their characteristic properties but also on enhancements, novel techniques and the use of heat exchangers (HXs), and microchannel heat exchangers (MCHEs) in these systems, as well as their development in recent years and their limitations. The main factors contributing to variations in the performance of HP systems are temperature and humidity in the ambient atmosphere. The present study is expected to support numerical and experimental performance analysis, and design miniaturisation via MCHEs. Unique designs or manufacturing techniques in MCHEs; various configurations in HP systems, depending on their load and environmental conditions; various nanofluids; and a comparison of nanofluids with different base metals are presented and discussed. Comparisons between various MCHEs and their respective limitations provide evidence-based guidelines for technology selection and designs for optimised operation at given environmental and load conditions.This work was financially supported by Brunel University of London BRIEF award and RCIF, Royal Society International Exchanges (IES\R3\183069) and Royal Society research grant (RGS\R2\222256)
Deflection Predictions of Tapered Cellular Steel Beams Using Analytical Models and an Artificial Neural Network
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Data will be available on request.Cellular steel beams are primarily used to accommodate electrical and mechanical services within their structural depth, helping to reduce the floor-to-ceiling height in buildings. These beams are often tapered for various reasons, such as connecting members (e.g., beams) of different depths, adjusting stiffness in specific areas, or enhancing architectural design. This paper presents an algorithm developed using MATLAB R2019a and an artificial neural network (ANN) to predict the deflection of tapered cellular steel beams. The approach considers the web I-section variation parameter (α), along with shear and bending effects that contribute to additional deflections. It also accounts for the influence of the stiffness of the upper and lower T-sections at the centreline of the web opening. To validate the model, a total of 1415 finite element models were analysed. The deflections predicted by the analytical and ANN models were compared with finite element results, showing good agreement.This research received no external funding
Influence of Piston Lubricant on the Distribution of Defects in Cold Chamber High Pressure Die Casting
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The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.Acknowledgments:
The technical support from UK site of ESI Group is greatly appreciated for software usage and model application. And the experiment appratus supplied by BCAST, Brunel University London is also acknowledged.In the cold chamber high pressure die casting process (CC-HPDC) for light alloys, the piston lubricants play a key role in protecting the piston tip from wearing and ensure adequate seal with the shot sleeve. However, during the production process, the pouring of overheated aluminum alloy melt into the shot sleeve would lead to evaporation and burning of the lubricants once in contact with the piston tip. The burning products, however, would form gas and non-metallic inclusions in the melt which would be transported and injected into the die area and finally trapped in the castings, all of which would affect the mechanical properties of the as-cast samples and deteriorate the product quality. To further investigate this issue, a pilot scale HPDC machine is used and the lubricant burning issue is studied based on material characterization and numerical modelling. The chemical composition, size, and morphology of the burned products are observed using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). In order to better explore the issue of lubricant combustion discovered in the experiment, a finite element model describing the entire HPDC process is established and the burning, motion, and trapping of the lubricant are calculated. The final distribution of the burned products such as gas and non-metallic inclusions are predicted and their influence on final solidification quality of the as-cast products under various process parameters are analyzed qualitatively. Finally, a slow shot velocity range of 0.4–0.6 m/s and an acceleration profile that ramps up to 0.3 m/s over 0–370 mm of the shot sleeve proved to be the most effective in reducing air entrainment and oxide inclusions to alleviate the burning of lubricant on final product quality.This research was funded by the National Science Foundation of China (52304360) and the Open foundation of the State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, China (K22-07), the Key Research and Development Program of Xiangjiang Laboratory (22XJ01002), and Engineering and Physical Sciences Research Council (EPSRC) and Jaguar Land Rover Ltd. [grant number 11055100]
Development of the E-Portal for the Design of Freeform Varifocal Lenses Using Shiny/R Programming Combined with Additive Manufacturing
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The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.This paper presents an interactive online e-portal development and application using Shiny/R version 4.4.0 programming for personalised varifocal lens surface design and manufacturing in an agile and responsive manner. Varifocal lenses are specialised lenses that provide clear vision at both far and near distances. The user interface (UI) of the e-portal application creates an environment for customers to input their eye prescription data and geometric parameters to visualise the result of the designed freeform varifocal lens surface, which includes interactive 2D contour plots and 3D-rendered diagrams for both left and right eyes simultaneously. The e-portal provides a unified interactive platform where users can simultaneously access both the specialised Copilot demo web for lenses and the main Shiny/R version 4.4.0 programming app, ensuring seamless integration and an efficient process flow. Additionally, the data points of the 3D-designed surface are automatically saved. In order to check the performance of the designed varifocal lens before production, it is remodelled in the COMSOL Multiphysics 6.2 modelling and analysis environment. Ray tracing is built in the environment for the lens design assessment and is then integrated with the lens additive manufacturing (AM) using a Formlabs 3D printer (Digital Fabrication Center (DFC), London, UK). The results are then analysed to further validate the e-portal-driven personalised design and manufacturing approach.This research received no external funding
Construct Validity in Cross-Cultural, Developmental Research: Challenges and Strategies for Improvement
Get PDFData Availability Statement: This manuscript does not rely on any data, code or other resources.This is a “preproof” accepted article for Evolutionary Human Sciences. This version may be subject to change during the production process.The recent expansion of cross-cultural research in the social sciences has led to increased discourse on methodological issues involved when studying culturally diverse populations. However, discussions have largely overlooked the challenges of construct validity- ensuring instruments are measuring what they are intended to- in diverse cultural contexts, particularly in developmental research. We contend that cross-cultural developmental research poses distinct problems for ensuring high construct validity, owing to the nuances of working with children and that the standard approach of transporting protocols designed and validated in one population to another risks low construct validity. Drawing upon our own and others’ work, we highlight several challenges to construct validity in the field of cross-cultural developmental research, including 1) lack of cultural and contextual knowledge, 2) dissociating developmental and cultural theory and methods, 3) lack of causal frameworks, 4) superficial and short- term partnerships and collaborations, and 5) culturally inappropriate tools and tests. We provide guidelines to address these challenges, including 1) using ethnographic and observational approaches, 2) developing evidence-based causal frameworks, 3) conducting community-engaged and collaborative research, and 4) culture-specific refinements and training. We discuss the need to balance methodological consistency with culture-specific refinements to improve construct validity in cross-cultural developmental research.This work was supported by a Cultural Evolution Society New Investigator Award and Society for Research in Child Development Early Career Scholars Grant to NJW, as well as a Cultural Evolution Society Workshop Fund to NJW. and BSR. BSR was also supported by a UKRI ESRC New Investigator Grant, number ES/Y005600/1
Navigating assessment challenges: Students’ reflection on preparation for exams, essays, presentations, and reports
Get PDFAssessments play a key role in students’ academic experience in higher education. This study investigates how students prepare for different types of assessments. Survey data collected from 104 BSc Psychology and BSc Psychology (Sport, Health and Exercise) and 90 BSc Biomedical Sciences students showed that there was a wide discrepancy regarding preparation time for assessments. Focus groups were conducted to gain deeper insights into students’ perception and preparation for assessments. Thematic analysis revealed three key themes: (1) the nature of the assessment influences the level of preparation, with multiple-choice exams often perceived as requiring minimal effort, while essays and lab reports demand more extensive critical thinking and preparation time; (2) procrastination is prevalent, especially for tasks that involve complex, in-depth work like
report writing; (3) peer collaboration plays a significant role, particularly in assessments that require structured thinking, such as essays and oral presentations. These findings underscore the need for educators to consider the diversity in student preparation strategies when designing assessments and support systems
High-Precision Satellite Clock Offset Estimated by SRIF Based on Epoch-Wise Updated Orbit
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No new data were created or analyzed in this study. Data sharing is not applicable to this article.High-precision clock offset products directly affect the performance and reliability of precise point positioning (PPP) applications. Currently, real-time clock offset products offered by institutions such as the Centre national d’études spatiales (CNES) rely on ultra-rapid predicted orbits. However, these orbits have limited accuracy and exhibit jumps during updates, constraining the accuracy of real-time clock estimation. To address this issue, we propose an undifferenced ambiguity resolution (UD AR) technique for clock offset estimation based on epoch-wise updated orbits. Clock estimation experiments were performed using both predicted and epoch-wise updated orbits, with square root information filtering (SRIF) applied in three schemes: double-differenced (DD), UD, and float solutions. Compared with predicted orbits, epoch-wise updated orbits provided smoother sequences with higher accuracy, significantly improving clock offset estimation accuracy in all schemes. Moreover, the UD AR solution significantly enhanced clock offset estimation accuracy, and the high-precision epoch-wise updated orbit products increased the narrow-lane fixing rate of the UD solutions. The clock accuracies of BDS-3, Galileo, and GPS reached 0.032 ns, 0.023 ns, and 0.026 ns, respectively, representing improvements of 36%, 34%, and 41% compared with the float solutions and 41%, 30%, 26% compared with the UD solution based on 1 h predicted orbits. Finally, the positioning performance of the proposed method was validated via PPP using 25 stations, showing improvements of 50%, 48%, and 41% in the north, east, and up directions compared with CNES products. Therefore, by combining epoch-wise updated orbit products with the UD AR to improve clock accuracy, this method provides a new approach to generating high-precision clock products, significantly contributing to enhancing PPP services.This work was supported by the Programs of the Fundamental Research Funds for the Central Universities (CHD 300102261301), the Special Fund for Basic Scientific Research of Central Colleges (CHD 300102262715), Natural Science Basic Research Program of Shaanxi (2019JC-20), Key Research and Development Program of Shaanxi (2022KW-09, 2021LLRH-06), Innovation Capability Support Program of Shaanxi (2021TD-03)
A Cryptocurrency Price Forecasting Model by Integrating Empirical Mode Decomposition and LSTM Neural Networks
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The data that support the findings of this study are openly available at https://www.cryptodatadownload.com/.Cryptocurrencies, such as Bitcoin and Ethereum, are digital assets that use cryptographic techniques to enable secure and decentralized transactions over the internet. Cryptocurrency prices exhibit highly nonlinear and non-stationary behavior, influenced by a wide range of financial and nonfinancial factors, including market liquidity, regulatory developments, technological advancements, security incidents, and geopolitical events. The unpredictable nature of these price fluctuations underscores the need for robust predictive models to aid investors in making informed financial decisions. In this paper, we propose EMD-LSTM, a novel hybrid model that integrates empirical mode decomposition (EMD) and long short-term memory (LSTM) networks to enhance the accuracy of cryptocurrency price forecasting. EMD is utilized to decompose raw price signals into intrinsic mode functions (IMFs), which help in handling non-stationarity and extracting meaningful patterns. LSTM, with its capability to capture long-term dependencies, is then applied to the decomposed signals to learn relevant temporal features from high-frequency historical data. Our experimental results demonstrate that the EMD-LSTM model significantly outperforms traditional forecasting methods, achieving superior RMSE and MAE scores. These findings highlight the potential of EMD-LSTM as an effective tool for traders, investors, and researchers seeking reliable cryptocurrency price predictions in volatile market conditions
The Role of BIM 6D and 7D in Enhancing Sustainable Construction Practices: A Qualitative Study
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Data are contained within the article.The construction industry in Kuwait is experiencing a transformative shift with the adoption of Building Information Modeling (BIM) technologies, particularly BIM 6D for sustainability analysis and 7D for facility management. This study investigates the integration of these dimensions to address sustainability challenges in Kuwait’s construction sector, aligning practices with the United Nations’ Sustainable Development Goals (SDGs). Through qualitative interviews with 15 stakeholders—including architects, engineers, and contractors—and analysis of industry reports, policies, and case studies, the research identifies both opportunities for and barriers to BIM adoption. While BIM offers significant potential for lifecycle analysis, waste reduction, and energy efficiency, its adoption remains limited, with only 27% of construction waste recycled. Challenges include high initial costs, a shortage of skilled personnel, and resistance to change. The study highlights actionable strategies, including enhanced regulatory frameworks, university curriculum integration, and professional training programs led by the Kuwait Society of Engineers, to address these barriers. It also emphasizes the critical role of collaboration among government bodies, industry leaders, and institutions like the Kuwait Institute for Scientific Research. Drawing from successful international BIM projects, the findings offer a practical framework for improving sustainability in arid regions, positioning Kuwait’s experience as a model for other Middle Eastern and North African countries. This research underscores the transformative role of BIM technologies in advancing global sustainable construction practices and achieving a more efficient and eco-friendly future.This research received no external funding
Fast Skill Transfer Method for Peg-in-Hole Assembly Tasks Under Varied Visual Conditions
No full textDeep Reinforcement Learning (DRL) has emerged as a transformative approach in robotic assembly, offering unparalleled adaptability and efficiency in automating complex tasks. However, existing DRL methods with weak generalization require retraining of policy when facing new assembly scenarios, which require a significant amount of interaction and may harm the robots or parts. This paper presents a fast skill transfer approach for submillimeter-level assembly tasks. The approach enables rapid adaptation to varying textures and lighting variations, which are commonly encountered in flexible manufacturing environments. The model parameters can be quickly adjusted to facilitate seamless adaptation. Specifically, a concise distance-based encoder model is proposed to extract the latent representation from the low dimensional seam-based image (SBI) and map the extracted feature to the distance space. Then, the fine-tuning strategy is used to align the features of new scenes with those in the source scenes. The transfer strategy necessitates only the retraining of the feature extraction model, obviating the need to retrain the underlying RL policy. Simulation and real-world experiments are conducted to evaluate the proposed method, and the transfer can be finished in a few minutes. The policy trained in the simulation can be transferred to the different real-world assembly scenes with the proposed method with an average success rate of 94.3%, highlighting its potential for practical applications.10.13039/501100012226-Fundamental Research Funds for the Central Universities (Grant Number: 2024ZYGXZR107);
Brunel Research Initiative & Enterprise Fund BRIEF;
GJYC Program of Guangzhou (Grant Number: 2024D03J0005);
National Key R&D Program of China (Grant Number: 2024YFB4709200)
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