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The fatigue life of H-type rigid hangers, crucial components in bridge engineering, is investigated in this study, particularly under the influence of torsional vibrations induced by wind loads. These hangers, integral to the integrity and longevity of bridge structures, are characterized by their high aspect ratio and low torsional stiffness, which predispose them to fatigue under such conditions. The focus of the research is the hangers of Dongping Bridge, located in Foshan, Guangdong. Through the application of theoretical analysis and finite element simulation using ABAQUS, the effects of bolting actions were simulated using connector elements, which enhanced computational efficiency and facilitated the stress analysis at the bolt holes in node plates. Furthermore, fe-safe fatigue analysis software was utilized to evaluate the fatigue life, adhering to established guidelines. The findings reveal that selecting an appropriate stiffness for the connector elements is critical in accurately simulating the bolting action. It was determined that the torsional amplitude at mid-span is a viable indicator for assessing fatigue damage. A torsional vibration control threshold of 6.25° is recommended for hangers measuring 40.212 meters in length.

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Amid growing concerns over global climate change and the need for sustainable infrastructure development, remote communities such as Rigolet in Newfoundland and Labrador (NL), which primarily rely on diesel generators, face unique challenges and opportunities. This study proposes a transition to a hybrid energy system (HES) that integrates wind and solar energy with battery storage and diesel generator backups. The feasibility and implications of this transformation in Rigolet were assessed using HOMER Pro software, contrasting it with the current diesel-centric model. The feasibility, environmental impact, and economic implications of implementing a HES in Rigolet were thoroughly examined. The methodology employed includes a detailed simulation and optimization of the HES configuration suitable for 125 households with a population of 327. The findings reveal that integrating wind and solar electricity with the existing diesel infrastructure, coupled with battery storage, reduced diesel consumption by 352 tons per year and Carbon Dioxide (CO2) emissions by 929 tons per year. Additionally, other pollutants such as Carbon Monoxide (CO), Particulate Matter (PM), Sulfur Dioxide (SO2), and Nitrogen Oxide (NO) were significantly reduced. The proposed system demonstrates a reasonable Net Present Cost (NPC) of \$5.17 million with a Levelized Cost of Energy (LCoE) of \$0.22/kWh. This shift towards a HES not only illustrates significant environmental advantages and an increase in the percentage of renewable energy but also provides economic benefits through cost reductions over the long term compared to the existing diesel-dependent configuration. The proposed system provides a reliable and sustainable energy solution for Rigolet, presenting a replicable and innovative model for other similar remote locations aiming for a greener future.

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This study investigates the impact of economic policy uncertainty (EPU) on the performance of African banks, utilising a panel of 35 publicly listed commercial banks from seven African countries over the period from 2000 to 2022. A fixed-effect estimation model was employed to analyse the data, revealing that EPU has a detrimental effect on bank performance in Africa. Additionally, a significant increase in non-performing loans was observed during periods of heightened EPU. The findings also indicate that bank size negatively impacts performance, whereas adequate capital buffers enhance bank performance during stress periods. These results underscore the importance of management efficiency, risk assessment, and capital adequacy in ensuring the robust performance of African banks. It is recommended that policymakers and regulators bolster the capital levels of African banks to fortify the sector. Moreover, the formulation of stable and non-disruptive economic policies is crucial to mitigate the adverse effects of EPU on the African banking sector.

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This comprehensive review investigates the ethical implications of artificial intelligence (AI)-driven predictive analytics in healthcare, with a focus on patient privacy, algorithmic bias, equitable access, and transparency. The study further explores the integration of these ethical considerations into educational frameworks to enhance the training and preparedness of healthcare professionals in the responsible use of AI technologies. A systematic literature review was conducted using databases such as PubMed, Scopus, and Google Scholar, employing keywords related to AI, predictive analytics, healthcare, education, and ethics. Articles published from 2017 onwards, discussing the ethical challenges and applications of AI in healthcare and educational settings, were included. Thematic analysis of selected articles revealed significant ethical concerns, including patient privacy, algorithmic bias, and equitable access to AI technologies. Findings underscored the necessity for robust data protection mechanisms, transparent algorithm development, and equitable access policies. The study also highlighted the importance of incorporating AI literacy and ethical training in medical education. An ethical framework was proposed, outlining strategies to address these challenges in both healthcare practice and educational curricula. This framework aims to ensure the responsible use of AI technologies, promote transparency, and mitigate biases in healthcare settings. By addressing a critical gap in understanding the ethical implications of AI-driven predictive analytics in healthcare and its integration into education, the study contributes to the development of guidelines and policies for the equitable and transparent deployment of AI. The proposed ethical framework provides actionable recommendations for stakeholders, aiming to enhance medical education and improve patient outcomes while upholding essential ethical principles.

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To maintain competitiveness and ensure long-term sustainability in the automotive sector, understanding the determinants of profit growth is crucial. This study empirically examines the impact of the Current Ratio (CR) and Net Profit Margin (NPM) on profit growth from 2018 to 2022, focusing on ten automotive companies listed on the Indonesia Stock Exchange. A quantitative methodology, utilizing panel data regression analysis and specifically the Fixed Effects Model (FEM), was employed to uncover significant insights. It was found that the CR positively influences profit growth, whereas the NPM exhibits a negative effect. These empirical findings offer valuable insights into financial management practices within the automotive industry. By understanding the impact of key financial metrics on profitability, investors, managers, and policymakers are better equipped to make informed decisions to optimize financial strategies for profit growth. This study contributes to the existing literature by addressing the relationship between the CR and NPM within the context of the automotive sector, an area where comprehensive analysis has been lacking. These insights are vital for informing strategic financial decisions and supporting the long-term health of the industry in a fiercely competitive global market.

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Studying the success factors of sustainability-focused business incubators is crucial because these incubators support startups that address environmental and social challenges, promoting sustainable development. Understanding these success factors enables incubators to provide targeted support that enhances the viability and impact of sustainable ventures. By optimizing the performance of sustainability incubators business will address global sustainability challenges and contribute to a more sustainable economy. This study aims to identify factors that support the success of a business incubator in a case study at Andalas University. This research used the Analytic Hierarchy Process (AHP) method, identifying ten factors with 49 subfactors supporting the incubator’s success. Impact Factor (I) with a weight of 0.2349, Output (O) with a weight of 0.1978, and Resource Capacity (SD) with a weight of 0.1286 are the three main factors that determine the success of an incubator. The prioritized subfactors are Contribution to Regional Economic Growth (I2) with a weight of 0.1898, Technology and New Products (O3) with a weight of 0.0711, and Cooperation with Industry (EK1) with a weight of 0.0477. These factors are recommended because they are expected to support the success of the Andalas University Business Incubator.

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This study aims to develop energy-efficient and environmentally friendly cooling solutions that are both effective and adaptable to various climates and structural forms. By leveraging computational fluid dynamics (CFD) software ANSYS and simulation software Engineering Equation Solver (EES), an innovative approach was undertaken. The investigation focused on the optimization of external air cooling via adjustable injectors operating at three distinct velocities, across three airflow rates. Concurrently, the adaptability of the cooling flow was enhanced by varying the number of turns in a coil within the heat exchanger's condenser section. This dual-phase method facilitated a comprehensive analysis across 54 scenarios, employing the EES software for the calculation of the coefficient of performance (COP) enhancement metrics. The efficiency of the cooling apparatus was rigorously evaluated by methodically altering the number of cooling tube turns and injection velocities. The apparatus comprised a loop-and-tube heat exchanger with a modifiable structure, where the second phase of the study addressed the thermal impact of air entry velocity and water spray mechanisms, featuring cooling tube adjustments ranging from five to thirteen turns. The initial phase examined the effects of air entry area and water spray techniques through variable injector configurations, with diameters of 15, 24, and 20 cm, and dimensions of 10 cm in height and 25 cm in length, alongside a conduit width of 60 mm. The findings revealed that the thermal dynamics of the heat exchanger and fluid flow are significantly influenced by the apparatus's geometry, particularly the air entry area and water spraying mechanism. Temperature and velocity contours illustrated that the number of loop turns and injections markedly affects system performance. An optimal configuration, consisting of 35 injectors and 13 coil turns, achieved a COP of 4.537 at an inlet velocity of 2.0 m/s, signifying the most effective system design identified within this study.
Open Access
Research article
Modeling Retail Price Volatility of Selected Food Items in Cross River State, Nigeria Using GARCH Models
nkoyo abednego essien ,
chikadibia alfred umah ,
lgbo-anozie uloma amarachi ,
timothy kayode samson
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Available online: 06-27-2024

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Food inflation presents a significant challenge in Nigeria. This study examines the volatility of four primary food items—tomatoes, yam, yellow garri, and imported rice—in Cross River State, Nigeria, utilizing data on monthly retail prices per kilogram from January 1997 to November 2023, sourced from the National Bureau of Statistics (NBS). Three asymmetric volatility models were employed: Exponential Generalized Autoregressive Conditional Heteroscedasticity (EGARCH), Threshold Autoregressive Conditional Heteroscedasticity (TARCH), and Power Autoregressive Conditional Heteroscedasticity (PARCH). The parameters of these models were estimated using three distributions of error innovations: Normal, Student's t-distribution, and Generalized Error Distribution (GED). The performance of the models was assessed based on log-likelihood for fitness and Root Mean Square Error (RMSE) for forecasting accuracy. The results indicated that non-Gaussian error innovations outperformed the normal distribution. Notably, higher persistence in volatility was observed for yam and tomatoes compared to yellow garri and imported rice. Tomatoes exhibited the highest volatility persistence among the food items analyzed. Significant Generalized Autoregressive Conditional Heteroscedasticity (GARCH) terms for tomatoes and yam suggested that past volatility has a significant positive impact on their current volatility, whereas this effect was not significant for yellow garri and imported rice (p$<$0.05). The leverage effect was found to be insignificant, indicating that positive and negative shocks in volatility exert similar effects on the volatility of these food items. These findings underscore the urgent need for incentives and adequate security measures to ensure food sufficiency in Cross River State and Nigeria at large.

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The towing limits for self-propelled rail track maintenance equipment (SP-TME) are influenced by a multitude of factors, including the type and weight of the equipment, speed, braking capabilities, track and weather conditions, traction, engine power, driveline performance, coupler/towing link integrity, and safety regulations. This study investigates these variables to determine their impact on the towing limits of SP-TME. Unlike traditional rail vehicles, SP-TME possesses unique operational constraints and specifications, necessitating careful consideration of its independent mobility. An extensive analysis was conducted on the towing usage and overuse of SP-TME during travel mode, examining various scenarios that incorporate different combinations of trailing load, rail track grade, rail curvature, and weather conditions. These scenarios, ranging from normal to worst-case, aim to simulate demanding operational environments. The parameters evaluated include structural strength, traction, engine and driveline performance, wheel rolling and skidding, braking capabilities, trailing load, speed, and track and weather conditions. Results indicate that under normal and moderate conditions, the equipment can tow significantly higher loads than the defined base load. However, in special situations, such as negotiating tighter curves and steeper grades in adverse weather conditions, wheel skidding and locking emerge as limiting factors. Findings related to service and parking brake performance during steep grade descents, particularly when the trailer lacks independent braking capabilities, are also presented. Recommendations and cautions are provided to ensure safe and efficient operation of SP-TME under various conditions.

Open Access
Research article
DNA-Level Enhanced Vigenère Encryption for Securing Color Images
abdelhakim chemlal ,
hassan tabti ,
hamid el bourakkadi ,
rrghout hicham ,
abdellatif jarjar ,
abdellhamid benazzi
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Available online: 06-25-2024

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This study presents the development of a novel method for color image encryption, leveraging an enhanced Vigenère algorithm. The conventional Vigenère cipher is augmented with substantial substitution tables derived from widely used chaotic maps in the cryptography domain, including the logistic map and the A.J. map. These enhancements incorporate new confusion and diffusion functions integrated into the substitution tables. Following the Vigenère encryption process, a transition to deoxyribonucleic acid (DNA) notation is implemented, controlled by a pseudo-random crossover matrix. This matrix facilitates a genetic crossover specifically adapted for image encryption. Simulations conducted on a variety of images of diverse formats and sizes demonstrate the robustness of this approach against differential and frequency-based attacks. The substantial size of the encryption key significantly enhances the system's security, providing strong protection against brute-force attacks.

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Effective waste management poses a significant challenge for transitional countries, particularly in the context of limited financial and material resources. In Bosnia and Herzegovina (BiH), the inefficiency of the waste management system at both the entity and national levels exacerbates the difficulty of establishing an integrated system resilient to natural and other hazards. This study introduces a theoretical model of comprehensive waste management (CWM) tailored for crisis situations, aiming to advance the development of a unified system across BiH. Key measures proposed include the involvement of key stakeholders, optimization of material resources, and continuous education to address irresponsible waste disposal practices and non-compliance with regulations. These issues contribute to the proliferation of illegal landfills and heighten the risk of large-scale environmental catastrophes. Specifically, in the Republic of Srpska, one of BiH's two entities, 400,000 tons of municipal waste were generated in 2020, averaging 0.95 kg per person per day, with approximately 40% being organic waste and another 40% packaging waste. Regrettably, only about 5% of this waste is recycled, largely due to an inadequate strategy and systemic approach to waste management, with about 30% of the population still lacking access to waste collection services. The proposed CWM model and the associated measures are crucial for mitigating the impacts of natural hazards, such as floods, on waste management systems.
Open Access
Research article
Calculation of Circumferential Stress in Steel Epoxy Sleeve-Reinforced Pipelines Under Internal Pressure
xinyang zhang ,
haonan liu ,
jiaqin zhang ,
yanke shi ,
leige xu
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Available online: 06-24-2024

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To address the lack of clear formulae for calculating the circumferential stress in steel epoxy sleeve-reinforced pipelines under internal pressure, this study constructs a mechanical model based on the specific stress characteristics of these pipelines. Using stress solution methods and deformation compatibility relationships, theoretical formulas for circumferential stress in the pipeline layer, epoxy resin layer, and sleeve layer under internal pressure are derived. The theoretical formulas are validated through numerical simulations using ANSYS software, which includes models with and without flanges. The calculations were performed for common pipelines with outer diameters of 219mm, 660mm, and 1219mm. The results show that the discrepancies between theoretical and numerical solutions of circumferential stress in all layers of both model types are within 10%. Specifically, the circumferential stress in the pipeline layer of the flanged model is lower than that of the non-flanged model and also lower than the theoretical values. The error between the theoretical and numerical solutions for pipelines of different diameters does not exceed 10%, confirming the validity and applicability of the theoretical formulas. This suggests that using the simplified mechanical model for circumferential stress calculations ensures a conservative approach for the structural assessment of pipelines. The formulas provided herein can serve as a reference for the design and evaluation of steel epoxy sleeve-reinforced pipelines under internal pressure.

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This study investigates the stability of steel columns subjected to axial compression, focusing on square hollow sections (SHS) with both uniform and non-uniform cross-sections. The stability of fixed-free end SHS columns with uniform cross-sections was initially verified using analytical equations. To obtain the critical load and design buckling resistance for each SHS column, Finite Element Analysis (FEA) was employed. The results indicate that while analytical equations can validate the stability of uniform SHS columns, they are insufficient for columns with non-uniform cross-sections. Consequently, the FEA emerges as a robust alternative for analyzing columns with varying cross-sections along their length. This study highlights the necessity of numerical methods for verifying the stability of structurally complex columns, such as those with perforations for mechanical and electrical applications. The finite element model was validated and applied to non-uniform cross-section columns, providing insights into the stability of these columns under practical conditions. This research aims to offer an alternative analytical approach for structural engineering applications where column stability is critical, especially for non-uniform cross-sectional designs that facilitate handling processes in various engineering scenarios.
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