bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure, Mechanical, and Tribological Characteristics of Heat-Treated AA7075 Composite Reinforced With High-Entropy Alloy Particles
Authors: Verma Pradip Kumar , Singh Alok , Bais Uday Pratap Singh , Kumar Akshay , Malik Nisha 
Published: December 2024

Abstract
This research examines the microstructural, mechanical, and tribological characteristics of an AA7075 alloy composite reinforced with high-entropy alloy (HEA) particulates, synthesized through advanced stir-squeeze casting techniques. To enhance grain refinement and optimize mechanical properties, the composite undergoes T6 heat treatment. Advanced characterization methods, including optical microscopy, scanning electron microscopy (SEM), and optical profilometry, are utilized to investigate microstructural features and worn surface morphology. Microstructural analysis reveals a homogeneous distribution of HEA particles within the AA7075 matrix, promoting a refined grain structure. Mechanical assessments indicate improvements in microhardness and compressive strength with the increasing HEA content. Tribological analysis shows that the wear-rate of the composite decreases with the increase in HEA particles, reaching a maximum reduction with 8 wt% HEA reinforcement. SEM observations of the worn surfaces reveal features such as pronounced grooves, adhesive wear, ploughing effects, wear debris, and microcracking.
Supercritical Carbon Dioxide Lubricated Hybrid Journal Bearing: Computational Fluid Dynamics Analysis and Optimization
Authors: Ali MD Shujan , Shin Dongil , Palazzolo Alan 
Published: December 2024

Abstract
Supercritical CO2 (SCO2) power cycles offer significant advantages in terms of thermal efficiency, cost-effectiveness, and environmental benefits. However, the successful implementation of these cycles depends on the design and analysis of bearings that can operate at high speeds and temperatures. Despite their importance, critical aspects like supporting bearings have received limited attention. This study addresses these gaps by developing sophisticated 3D computational fluid dynamics (CFD) models to accurately predict static characteristics like load capacity and leakage rate of SCO2-lubricated hybrid bearings. These bearings use SCO2 as the lubricating fluid due to the difficulty in maintaining separation between oil and the process fluid in oil-based bearings operating at extreme temperatures and pressures. An optimization tool, response surface optimization along with a 3D CFD model has been utilized to determine the bearing equilibrium point. After validation of the CFD model against available experimental measurements, a parametric study has been conducted to evaluate the effects of various geometric and operating parameters on bearing performance. The hybrid bearing geometry has been optimized based on the findings of the parametric study. The optimized bearing designs achieved a significant boost in load capacity while substantially reducing the leakage rate. This study introduces a new design/optimization process for SCO2-lubricated bearings using a 3D CFD model. The results indicate a strong correlation between load capacity, leakage rate, and variables such as orifice diameter, supply pressure, recess height, and recess length. These insights provide valuable guidance for practical SCO2-lubricated hybrid bearing design and optimization.
Local Calculation of Load-Dependent Gear Power Losses of Cylindrical Gears
Authors: Paschold Constantin , Lohner Thomas , Stahl Karsten 
Published: December 2024

Abstract
The primary design criteria for gearboxes are (i) power density and load capacity; (ii) noise, vibration, and harshness; and (iii) efficiency and heat balance. To meet these design criteria, it is essential to use accurate calculation models throughout the design process. The total power loss can be divided into portions of gears, bearings, seals, and other machine elements, of which the load-dependent gear power loss often makes up the most significant portion. The existing literature provides a number of calculation methods with varying levels of detail for mesh-local models that promise high accuracy; however, these are rarely used, partly due to a lack of validation. This study systematically compares mesh-averaged and mesh-local calculation models using experimental results from a twin-disk tribometer and various cylindrical gears. The study includes a wide range of operating conditions and different gear oils. Three calculation levels I, II, and III are defined. The results show good agreement between the calculated and measured load-dependent gear power losses, with the mesh-local models showing high accuracy. When comparing results for an internal gear, the mesh-local calculation model calculates 30% lower load-dependent gear power losses than the mesh-averaged calculation model, which aligns with initial experimental results. The findings of this study suggest that mesh-local models are viable for wider application.
Microstructure and Friction Characteristics of SiC/Ni60 Coatings by Different Directed Energy Deposition Laser Powers
Authors: Li Wanyang , Liu Weiwei , Ma Zongyu , Liu Huanqiang , Song Jianrong , Li Tao , Wang Fengtao , Zhao Yue , Zhang Hongchao 
Published: December 2024

Abstract
The microstructure and tribological characteristics of SiC/Ni60 composite coatings manufactured using directed energy deposition (DED) technology are investigated. The influence of different laser powers on the composites is studied. The evolution characteristics of the microstructure, the stepped variation pattern of microhardness, and the formation mechanism of wear resistance induced by different laser powers are observed in SiC/Ni60 composite coatings. Laser power variations emerged as crucial factors for improving the structure and performance of the composites. The relationship between microstructure, phase identification, and laser power is clarified using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), electron back-scattered diffraction (EBSD), and X-ray diffractometer (XRD). The best laser power is determined to be 3000 W based on microhardness and tribological characteristics. Additionally, the friction coefficient, wear rate, and wear behavior provide insights into the tribological features. Appropriate laser power parameters can suppress severe abrasive and adhesive wear and reduce the area of oxidative wear, resulting in a 51.99% reduction in wear rate. From the results obtained, it is evident that selecting the appropriate laser power provides a valuable direction for improving the performance of the composite coatings. The present work is expected to be applied to components such as crankshafts, where enhanced wear resistance is required.
Assessment of Tool Condition and Surface Quality Using Hybrid Deep Neural Network: CNN-LSTM-Based Segmentation and Statistical Analysis
Authors: Rao K. Venkata 
Published: December 2024

Abstract
Effective and precise prediction of tool wear plays a key role in improving machining efficiency, and product quality and reducing production cost. The majority of earlier studies have depended on limited experimental data, which may not be sufficient to estimate tool wear and surface quality. Aiming at these issues, the present study proposed a convolutional neural network (CNN)-long short-term memory (LSTM) hybrid deep neural network model that directly utilizes heterogeneous data including timely captured tool images, working conditions, vibration data, surface roughness, flank wear length, and wear depth. First, experiments were conducted on AISI D2 steel at three levels of spindle speed and feed/tooth, and experimental results for wear length, wear depth, surface roughness, and vibration signals were collected. The time domain vibration signals were processed with a fast Fourier transformer and converted to the frequency domain, and 13 and 5 features were extracted from the time and frequency domain, respectively, and integrated with the heterogeneous data. Second, tool images were annotated using Roboflow software, and wear region information was collected using YOLOv8 and added to heterogeneous data. Third, the CNN-LSTM network was trained with heterogeneous data containing spatial and time-dependent features. The performance and accuracy of the proposed methodology were validated using experimental data collected at different working conditions. The results show that the CNN-LSTM model effectively predicted the tool wear length on the flank, with the root mean square error (RMSE) value of 0.219 mm, and the determination coefficient R2 value of 0.974; wear depth with the RMSE value of 0.018 mm and R2 value of 0.943; surface roughness with the RMSE value of 0.216 μm and R2 value of 0.956. The proposed methodology has significance in metal-cutting applications and provides a solution to predict tool conditions and surface quality accurately.
A New Multi-Criteria Decision-Making Tool for Subsea Oil and Gas Asset Decommissioning
Authors: Caprace Jean-David , de Souza Marcelo I. L. , Violante Ferreira Claudio , Ribeiro Nicolosi Eduardo 
Published: December 2024

Abstract
The decommissioning of offshore oil and gas (O&G) facilities poses significant challenges due to high costs, operational risks, social impacts, and environmental protection concerns. Multi-criteria decision analysis (MCDA) emerges as a vital tool to navigate these complexities, enabling stakeholders to evaluate diverse decommissioning alternatives against a broad set of criteria. Existing literature lacks extensive documentation on the application of MCDA in decommissioning decisions, particularly in quantitatively evaluating the performance of different decommissioning strategies against a comprehensive set of criteria. This study introduces a novel MCDA model tailored for the decommissioning of subsea O&G assets, aiming to improve decision-making by providing a quantitative ranking of decommissioning alternatives. Employing the Preference Ranking Organization Method for Enrichment Evaluations method, the model considers 37 attributes across six criteria (safety, environment, waste management, technical, social, and economic) to evaluate several decommissioning alternatives for the Brazilian Espadarte Field. Weightings and scenarios are defined through expert consultation, enhancing the model’s adaptability and relevance to real-world contexts. The model’s application demonstrated significant efficacy, with the selected top-ranked decommissioning alternative achieving a performance indicator of 58%, corresponding to the removal of 50% of the pipeline length considered. This result underscores the model’s capacity to identify optimal compromises between competing criteria. The study contributes to the field by filling the gap in the quantitative evaluation of decommissioning alternatives, offering a robust, transparent decision-making tool that accommodates complex, multi-criteria decisions. The model provides a significant advancement in the rationalization of decommissioning strategies for O&G assets.
Validation of a Frequency-Dependent Morison Force Formulation for a Large Monopile in Severe Irregular Seas
Authors: Dadmarzi Fatemeh H. , Bachynski-Polić Erin E. , Pakozdi Csaba , Thys Maxime 
Published: December 2024

Abstract
Motivated by the increased interest in renewable energy and the need for validated hydrodynamic load models, a rigid monopile and a fully flexible large monopile wind turbine have been tested experimentally at a 1:50 model scale in irregular waves. Furthermore, a new engineering load model combining the conventional Morison equation for slender bodies with a frequency-dependent mass coefficient based on the first-order MacCamy and Fuchs solution has been developed and compared to Rainey’s load model and the model test results. Nonlinear wave kinematics based on the results of the nonlinear potential code REEF3D::FNPF have been applied as input to the numerical models. The new model better estimates the response of the monopile in the frequency range relevant for ringing events. The experimentally obtained 90th percentile bending moment response near the first natural frequency of the monopile is estimated within 2% by the new model with frequency-dependent mass coefficient, while a traditional Morison approach or the Rainey model overestimate the response by 47% and 74%, respectively.
Simulation of Rock-Breaking Ability of Polycrystalline Diamond Compact Cutter Based on Rock Mechanics Experiment After Heat Treatment
Authors: Yin Qishuai , Wen Zhiliang , Ren Laiao , Qu Ximo , Li Qianyu , Zhou Bo 
Published: December 2024

Abstract
When drilling in geothermal and deep formations, the rock-breaking mechanism of high-temperature formations is not clear. In this work, mechanical tests of rocks subjected to high temperatures were carried out, and rock-breaking models of bottom hole thermal stress dispersion and polycrystalline diamond compact (PDC) cutter were established. Aiming at efficient rock breaking pursued by drilling in high-temperature formation, rock-breaking simulations of PDC cutters with different front rake angles under the condition of temperature and confining pressure changes were carried out based on critical penetration depth. The mechanism of rock breaking is analyzed from the point of view of stress variation in the process of brittle rock breaking. The study shows that rock plasticity is enhanced after high temperature, and the temperature difference between the drilling fluid and bottom hole will make the outer part of the bottom hole shrink obviously. Under the conditions of this study, the optimal rock-breaking angle of the PDC cutter is 20 deg. The confining pressure of deep high-temperature formation will hinder rock breaking at a lower value range, and rocks under high confining pressure are more prone to brittle fracture. The increase of rotational speed has an obvious promotion stage for efficient rock breaking, and too large rotational speed will result in low brittle rock-breaking efficiency. These works are helpful in understanding the efficient brittle rock-breaking mechanism in high-temperature drilling, and can provide references for tooth design and rotational speed optimization of PDC bits.
Online Measurement of Impedance Spectroscopy of Lithium-Ion Batteries Based on Equalized Current Harmonic Injection
Authors: Chen Long , Chen Haisen , Liao Li , Jiang Jiuchun , Wang Lujun 
Published: December 2024

Abstract
Impedance spectroscopy can characterize a variety of states within a battery and shows great potential for application in safety warning and condition assessment, but there is a lack of an effective online monitoring method. Therefore, this article proposes a method for online measurement of impedance spectroscopy based on harmonic injection of equalization currents, which superimposes different frequency sinusoidal perturbation signals on the original equalization currents through process reconstruction and collaborative control, and realizes real-time impedance spectroscopy monitoring at the level of single cell without additional hardware. In order to verify the validity of the method proposed in this article, a hardware experimental platform was constructed. First, a four-switch buck-boost (FSBB) converter is used to perform energy equalization of a six-cell Li-ion battery pack under different working conditions, and the experimental results show that the Li-ion battery pack can be equalized by the active equalization circuit under the states of resting, charging, and discharging in about 60 min, 75 min, and 100 min, respectively. Then, the impedance spectroscopy in the frequency range of 0.2 Hz–800 Hz is achieved through the collaborative control of active equalization and impedance spectroscopy. Finally, in order to verify the reliability of the measured data, the measured impedance spectroscopy data were evaluated by the Kramers–Kronig (K-K) transforms, and the data measured at the initial stage were compared and analyzed with the data measured by a professional electrochemical workstation, which verified the validity of the method proposed in this article.
Microbiome composition and turnover in the face of complex lifecycles and bottlenecks: insights through the study of dung beetles
Authors: Jones Joshua A. , Newton Irene Garcia , Moczek Armin P. 
Published: December 2024

ABSTRACT

Microbiome composition and function often change throughout a host’s life cycle, reflecting shifts in the ecological niche of the host. The mechanisms that establish these relationships are therefore important dimensions of host ecology and evolution; yet, their nature remains poorly understood. Here, we sought to investigate the microbial communities associated with the complex life cycle of the dung beetle
Onthophagus taurus
and the relative contributions of host life stage, sex, and environment in determining microbiome assembly. We find that
O. taurus
plays host to a diverse microbiota that undergo drastic community shifts throughout host development, influenced by host life stage, environmental microbiota, and, to a lesser degree, sex. Contrary to predictions, we found that egg and pupal stages—despite the absence of a digestive tract or defined microbe-storing organs—do not constrain microbial maintenance, while host-constructed environments, such as a maternally derived fecal pellet or the pupal chamber constructed by late larvae, may still serve as complementary microbial refugia for select taxa. Lastly, we identify a small community of putative core microbiota likely to shape host development and fitness. Our results provide important insights into mechanisms employed by solitary organisms to assemble, maintain, and adjust beneficial microbiota to confront life-stage-specific needs and challenges.

IMPORTANCE

As the influence of symbionts on host ecology, evolution, and development has become more apparent so has the importance of understanding how hosts facilitate the reliable maintenance of their interactions with these symbionts. A growing body of work has thus begun to identify diverse behaviors and physiological mechanisms underpinning the selective colonization of beneficial symbionts across a range of host taxa. Yet, how organisms with complex life cycles, such as holometabolous insects, establish and maintain key symbionts remains poorly understood. This is particularly interesting considering the drastic transformations of both internal and external host morphology, and the ecological niche shifts in diet and environment, that are the hallmark of metamorphosis. This work investigates the dynamic changes of the microbiota associated with the complex life cycle and host-constructed environments of the bull-headed dung beetle,
Onthophagus taurus
, a useful model for understanding how organisms may maintain and modulate their microbiota across development.
Chlorine disinfectant significantly changed microfauna habitat, community structure, and colonization mode in wastewater treatment plants
Authors: Zhong Yuening , Zhang Yibo , Meng Qiyue , Zhang Haoyu , Wu Zhenbing , Dang Chenyuan , Fu Jie 
Published: December 2024

ABSTRACT

During the coronavirus disease 2019 epidemic, excessive chlorine disinfectants have been used to block the spread of severe acute respiratory syndrome-coronavirus 2, resulting in large amounts of residual disinfectants entering wastewater treatment plants (WWTPs) through sewage systems. So far, no relevant research has been conducted on the impact of chlorine disinfectants on microfauna, an important microbial component in activated sludge treatment systems. This study comprehensively investigated the changes in microfauna habitat, community structure, and colonization mode under the chlorine stress by combining the full-scale WWTP survey and laboratory-scale sequencing batch reactor experiments. The results showed that chlorine disinfectants significantly changed the community structure of microfauna, including decrease in sedentary ciliates and increase in free-living ciliates, amoebas, and flagellates. Besides the disinfection effect of chlorine disinfectants, the microfauna community was also influenced by changes in habitat and bacterial community. The loose structure and excessive extracellular polymeric substance (EPS) of activated sludge caused by chlorination would impact the colonization of sedentary ciliates, while it was conducive to the survival of free-living ciliates due to their predation on EPS as the nutrients. Bacteria in the activated sludge had strong interactions with protozoa, and their changes under chlorine stress directly affected the protozoan community and even indirectly affected the micro-metazoa community through the food chain.

IMPORTANCE
This study revealed that chlorine disinfectant significantly changed microfauna habitat, community structure, and colonization mode in wastewater treatment plants during the coronavirus disease 2019 pandemic. Chlorine disinfectant could destroy the structure and stability of sludge flocs, reduce the abundance of beneficial microfauna in activated sludge, and even affect the colonization of sedentary ciliates on sludge. In addition, chlorine disinfectants might induce environmental and ecological risks related to microfauna, such as elevated suspended solids and release of bacteria and microfauna in the effluents.
Conformational changes in and translocation of small proteins: insights into the ejection mechanism of podophages
Authors: Zheng Jing , Xiao Hao , Pang Hao , Wang Li , Song Jingdong , Chen Wenyuan , Cheng Lingpeng , Liu Hongrong 
Published: December 2024

ABSTRACT

Podophage tails are too short to span the cell envelope during infection. Consequently, podophages initially eject the core proteins within the head for the formation of an elongated trans-envelope channel for DNA ejection. Although the core proteins of bacteriophage T7 have been resolved at near-atomic resolution, the mechanisms of core proteins and DNA ejection remain to be fully elucidated. In this study, we provided improved structures of core proteins in mature T7 and the portal–tail complex in lipopolysaccharide-induced DNA-ejected T7 to resolutions of approximately 3 Å. Using these structures, we identified three small proteins, namely gp14, gp6.7, and gp7.3, and illustrated the conformational changes in and translocation of these proteins from the mature to DNA-ejected states. Our structures indicate that gp6.7, which participates in the assembly of the core and trans-envelope channel, is a core protein, and that gp7.3 serves as a structural scaffold to assist the assembly of the nozzle into the adaptor.

IMPORTANCE
Podophage T7 core proteins form an elongated trans-envelope channel for genomic DNA delivery into the host cell. The structures of the core proteins within the mature T7 and assembled in the periplasmic tunnel form in the DNA-ejected T7 have been resolved previously. Here, we resolved the structures of two new structural proteins (gp6.7 and gp7.3) within mature T7 and receptor-induced DNA-ejected T7. The gp6.7 protein participates in the assembly of the core complex within mature T7 and the trans-envelope channel during T7 infection; therefore, gp6.7 is a core protein. Before T7 infection, gp7.3 plays a role in promoting the assembly of the nozzle into the adaptor.