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Experimental Evaluation of Turning AISI 304 Using Minimum Quantity Lubrication With Vegetable‐Based Green Cutting Fluids
Full text linkCutting fluids play a crucial role in dissipating the heat generated during machining operations, contributing to improved service life and machinability of tools and workpieces. Even though commercially available conventional cutting fluids are effective in serving their intended roles during the machining process, they are non‐biodegradable. Previous researchers have introduced a variety of environmentally friendly alternatives, among which green cutting fluids stand out due to their biodegradability and availability. The present study focuses on a comparative assessment of the machining performance of green cutting fluids, made from oil‐water emulsions derived from coconut oil, sunflower oil, and palm oil, with a conventional cutting fluid (MAK Sherol B) during the turning operation of AISI 304 stainless steel. Tween 20 is used as the emulsifying agent for preparing oil‐water emulsion. The machining performance was investigated by examining the impact of these cutting fluids on cutting speed, feed rate, and depth of cut on tool tip interface temperature, surface roughness, and cutting force during the turning process. Surface roughness values are determined using surface profilometry and Atomic Force Microscopy (AFM). The results indicate that palm oil has rendered the lowest cutting force and cutting temperature with improved surface quality under higher feed rates, cutting speeds, and depths of cut as compared with sunflower oil, coconut oil, and conventional cutting fluid
Experimental Evaluation of Turning AISI 304 Using Minimum Quantity Lubrication With Vegetable‐Based Green Cutting Fluids
Full text linkCutting fluids play a crucial role in dissipating the heat generated during machining operations, contributing to improved service life and machinability of tools and workpieces. Even though commercially available conventional cutting fluids are effective in serving their intended roles during the machining process, they are non‐biodegradable. Previous researchers have introduced a variety of environmentally friendly alternatives, among which green cutting fluids stand out due to their biodegradability and availability. The present study focuses on a comparative assessment of the machining performance of green cutting fluids, made from oil‐water emulsions derived from coconut oil, sunflower oil, and palm oil, with a conventional cutting fluid (MAK Sherol B) during the turning operation of AISI 304 stainless steel. Tween 20 is used as the emulsifying agent for preparing oil‐water emulsion. The machining performance was investigated by examining the impact of these cutting fluids on cutting speed, feed rate, and depth of cut on tool tip interface temperature, surface roughness, and cutting force during the turning process. Surface roughness values are determined using surface profilometry and Atomic Force Microscopy (AFM). The results indicate that palm oil has rendered the lowest cutting force and cutting temperature with improved surface quality under higher feed rates, cutting speeds, and depths of cut as compared with sunflower oil, coconut oil, and conventional cutting fluid
A Study on 3D Printed CFRP-Metal Sandwich Structures for Hydrogen Transportation and Storage in Aerospace and Automotive Systems
Full text linkThis study investigates the mechanical performance of 3Dprinted Carbon Fiber Reinforced Polymer (CFRP)-metal sandwich structures, focusing on infill pattern, infill ratio, and build orientation. The work primarily targets lightweight applications in hydrogen storage for aerospace and automotive sectors. Tensile and flexural tests were first conducted on non-sandwich specimens based on an earlier study [1], considering (i) infill patterns - Gyroid and Triangular and (ii) infill ratios -30%, 40%, and 52%. In tensile tests, strength increased with infill ratio, with Triangular infill consistently outperforming Gyroid, peaking at 863 N (Triangular 52%) versus 777.5 N (Gyroid 52%). Lower displacement in Triangular indicated higher stiffness. Flexural tests on non-sandwich specimens showed Gyroid 40% achieving the highest load (644.85 N), while Triangular 52% exhibited steady strength gains with increasing density. Selected configurations were further tested in sandwich structures (CFRP–stainless steel with nickel coating), where Gyroid 40% demonstrated the highest load-bearing capacity (1008.55 N), followed by Triangular 52% (717.09 N). Notably, Gyroid 52% showed the greatest extension (14.38 mm) despite lower strength, indicating enhanced ductility. Overall, the results highlight a trade-off between stiffness and compliance, suggesting Triangular infill for high-strength, rigid components and Gyroid for balanced flexural performance. Overall, this work provides an impactful study on optimizing CFRP-metal hybrid designs for hydrogen storage system
An Approach to Formal Verification of Autonomous Vehicle Systems using Threat Analysis
Full text linkThe rapid advancement and deployment of connected and autonomous vehicles (CAVs) present transformative opportunities to enhance safety, efficiency, and convenience within the transportation industry. However, these innovations introduce significant cybersecurity risks due to the complex electronics and continuous connectivity that CAVs depend on. Traditional testing methods, while critical, often fall short in detecting vulnerabilities across the vast range of scenarios these vehicles may encounter. Formal verification, a mathematical approach to system validation, offers a more rigorous and comprehensive solution by ensuring that systems operate as expected to search through all possible execution paths. However, defining appropriate system properties for verification remains a challenge, as a system designer may write properties that fail to address real-world threats effectively. This research addresses this gap by integrating threat analysis into the process of defining security properties, ensuring that the verification process is aligned with actual cybersecurity risks. We leverage Natural Language Processing (NLP) to extract key security details from threat analysis result texts, automating the generation of system properties. This approach simplifies the verification process, with its usability demonstrated through a high-level 5G-V2X design use case scenario
Cyber-Physical Integration and Experimental Validation of Impeller Failures Using IoT-Enabled Digital Twin Framework
Full text linkThis interdisciplinary study investigates impeller failure using a combined digital and experimental approach, establishing a proof of concept for cyber-physical integration. First, a CAD model was developed and its structural integrity is validated using Finite Element Analysis (FEA) to ensure the impeller could withstand operational loads and dynamic stresses, following the methodology outlined in [1]. Next, an IoT-enabled digital twin framework was implemented with Arduino-based sensors (temperature, humidity, vibration) to monitor 3D-printed impellers made from 316L stainless steel and AlSi10Mg aluminium. The sensors were integrated with a custom test rig driven by a motor capable of 10,000 rpm, with data acquired via analog/digital interfaces and visualized in Node-RED, streaming in real time to an IoT cloud platform. Impeller experiments ran for over 80 hours and were tested under two corrosive conditions: (i) engine oil (5W-30) and (ii) saltwater. SEM/EDS analysis revealed carbon deposits on oil-exposed samples and aluminium oxide on saltwater-exposed ones, while further SEM imaging showed pitting and corrosion. Alicona surface roughness tests confirmed degradation under dynamic loads. Preliminary real-time monitoring demonstrated the of predictive maintenance alerts, though fullscale validation remains future work. Overall, the developed framework provides a robust basis for physical testing with digital representation, offering strong potential for predictive maintenance
Large language model-based multiagent collaboration for abstract screening toward automated systematic reviews
Full text linkSystematic reviews (SRs) are essential for evidence-based practice but remain labor-intensive, especially during abstract screening. This study evaluates whether multiple large language models (multi-LLMs) collaboration can improve the efficiency and reduce costs for abstract screening. Abstract screening was framed as a question-answering (QA) task using cost-effective LLMs. Three multi-LLM collaboration strategies were evaluated, including majority voting by averaging opinions of peers, multi-agent debate for answer refinement, and LLM-based adjudication against answers of individual QA baselines. These strategies were evaluated on 28 SRs of the CLEF eHealth 2019 technology-assisted review benchmark using standard performance metrics such as mean average precision (MAP) and work saved over sampling at 95% recall (work saved over sampling WSS@95%). Multi-LLM collaboration significantly outperformed QA baselines. Majority voting was overall the best strategy, achieving the highest MAP 0.462 and 0.341 on subsets of SRs about clinical intervention and diagnostic technology assessment, respectively, with WSS@95% 0.606 and 0.680, enabling in theory up to 68% workload reduction at 95% recall of all relevant studies. Multi-agent debate improved weaker models most. Our own adjudicator-as-a-ranker method was the second strongest approach, surpassing adjudicator-as-a-judge, but at a significantly higher cost than majority voting and debating. Multi-LLM collaboration substantially improves abstract screening efficiency, and the success lies in model diversity. Making the best use of diversity, majority voting stands out in terms of both excellent performance and low cost compared to adjudication. Despite context-dependent gains and diminishing model diversity, multi-agent debate is still a cost-effective strategy and a potential direction of further research
Effectiveness of Mandated Approaches to Increasing Board Independence in Achieving Intended Governance Outcomes:Professional Investors’ Perspective
Full text linkDrawing on interviews with 27 professional investors and proceeding from a resource dependence theoretical lens, this study investigates how professional investors perceive the effectiveness of mandated approaches to increasing board independence in achieving intended governance goals in the Nigerian banking sector. We inductively identify three distinct effectiveness categories for board independence approaches: quixotic, symbolic, and practical. We further unpack seven contextual factors that influence these perceptions, namely person-specific utility; board cronyism; loss of independence over time; disconnection with business realities despite their technical competence; non-executive directors’ (NEDs’) concern for business survival; NEDs’ subservience to the major shareholder; and NEDs’ reputational standing. We provide insights that demonstrate that the mandated approaches to increasing board independence are not universally effective in achieving intended governance goals and must instead be evaluated within their institutional and contextual realities
Understanding sickness presenteeism: causes, risks and solutions: guidelines series
No full textWorking while not fully fit is not inherently harmful and can be beneficial, as long as the illness is neither contagious nor overly debilitating. Work benefits wellbeing in many ways, providing structure, purpose and opportunities to build confidence and self-esteem, while also facilitating social interaction and support. Working during recovery from illness or injury can also aid rehabilitation by helping employees gradually ease back into their roles via phased approaches. However, research shows that sickness presenteeism can have significant negative consequences. It can hinder recovery, increase the likelihood of future health issues and lead to higher absenteeism. Sickness presenteeism also raises health and safety concerns, as it can contribute to the spread of contagious disease in the workplace, as well as cause errors, accidents and injuries that affect not only the unwell employee but also their colleagues and the public. On a cultural level, working while sick can also increase pressure for others to do the same, normalizing unhealthy work practices.A recent guide published by the Society of Occupational Health [1] provides professionals in occupational health, human resources and related fields with a comprehensive overview of the causes, risks and management of sickness presenteeism. It examines its prevalence and highlights the key occupational, organizational and personal risk factors, along with how they can interact. The guide also examines the broader implications of working while unwell in on-site and remote work, focusing on employee health, performance and the wellbeing of others. This article summarizes the guide, presenting key points for practitioners on the causes, impact and management of sickness presenteeism. Selected citations are included, with more detailed references available in the guide.W H AT I S SI CK N E SS P R E SE N T E E I S M A ND HOW PR E VA LEN T IS IT ?Sickness presenteeism refers to attending work while unwell, whether due to physical or mental health issues, rather than taking time off to rest and recover. While awareness of its prevalence and impact is growing, sickness presenteeism remains difficult to quantify as it often goes unreported or unnoticed [2]. Reducing sickness absence remains a priority for many organizations, but presenteeism is not only more common but potentially more costly. A recent survey of over 1000 human resource professionals in the UK [3] found 76% had observed presenteeism among office-based workers and 78% among remote staff in the previous 12months. This trend seems particularly pronounced in cases involving mental health issues and other ‘hidden’ conditions [3, 4]. Moreover, the Institute for Public Policy Research [5] has estimated that, on average, 44 days of productivity are lost due to working while unwell, up from 35days in 2018.Increasing recognition of the prevalence and costs associated with sickness presenteeism highlights the importance of understanding the factors that drive people to work while ill and to develop effective strategies for identifying and mitigating this behaviou