bluuebunny/crossref_metadata_2025 huggingface dataset:
Advancements in Additive Manufacturing for Copper-Based Alloys and Composites: A Comprehensive Review
Authors: Vahedi Nemani Alireza , Ghaffari Mahya , Sabet Bokati Kazem , Valizade Nima , Afshari Elham , Nasiri Ali
Published: March 2024

Copper-based materials have long been used for their outstanding thermal and electrical conductivities in various applications, such as heat exchangers, induction heat coils, cooling channels, radiators, and electronic connectors. The development of advanced copper alloys has broadened their utilization to include structural applications in harsh service conditions found in industries like oil and gas, marine, power plants, and water treatment, where good corrosion resistance and a combination of high strength, wear, and fatigue tolerance are critical. These advanced multi-component structures often have complex designs and intricate geometries, requiring extensive metallurgical processing routes and the joining of the individual components into a final structure. Additive manufacturing (AM) has revolutionized the way complex structures are designed and manufactured. It has reduced the processing steps, assemblies, and tooling while also eliminating the need for joining processes. However, the high thermal conductivity of copper and its high reflectivity to near-infrared radiation present challenges in the production of copper alloys using fusion-based AM processes, especially with Yb-fiber laser-based techniques. To overcome these difficulties, various solutions have been proposed, such as the use of high-power, low-wavelength laser sources, preheating the build chamber, employing low thermal conductivity building platforms, and adding alloying elements or composite particles to the feedstock material. This article systematically reviews different aspects of AM processing of common industrial copper alloys and composites, including copper-chrome, copper-nickel, tin-bronze, nickel-aluminum bronze, copper-carbon composites, copper-ceramic composites, and copper-metal composites. It focuses on the state-of-the-art AM techniques employed for processing different copper-based materials and the associated technological and metallurgical challenges, optimized processing variables, the impact of post-printing heat treatments, the resulting microstructural features, physical properties, mechanical performance, and corrosion response of the AM-fabricated parts. Where applicable, a comprehensive comparison of the results with those of their conventionally fabricated counterparts is provided.
Study on Assessment of Collision Probability between Ship and Bridge Based on Automatic Identify System Data
Authors: Pan Jin , Wang Yong , Wang Tao , Xu Mingcai
Published: March 2024

With the development of bridge crossings over rivers, the accident of the vessel–bridge collision is increasing as well. It is important to assess probability of bridges colliding with passing ships. Firstly, the AIS (Automatic identify system) data was collected and decoded to obtain the dynamic information of the ships passing the bridge including the distributions of ships position, speed, and yaw angle, which are then compared with the value recommended by the AASHTO (American Association of State Highway and Transportation Officials) specification. The mainly influential parameters of ship–bridge collision obtained from AIS data are used to correct the variables in the risk assessment of AASHTO specification, which intends to improve the assessment accuracy by considering the actual information of passing vessels. The collision probability with and without considering the actual situations of passing ships are compared. It is found that the distribution and transit path of passing ships significantly influence the collision probability. To improve the risk assessment accuracy, it is suggested to use the actual distributions of passing ships from AIS data.
Four New Fungal Species in Forest Ecological System from Southwestern China
Authors: Deng Yinglian , Li Jinfa , Zhao Changlin , Zhao Jian
Published: March 2024

Four new wood-inhabiting fungi were found in Southwestern China within the genera Phanerochaete, Phlebiopsis, Asterostroma, and Vararia of the families Phanerochaetaceae and Peniophoraceae, belonging to the orders Polyporales and Russulales individually. Combined with their morphological characteristics and molecular biological evidence, the present study describes them as new fungal taxa. Asterostroma yunnanense is characterized by the resupinate, membranaceous to pellicular basidiomata with a cream to salmon-buff hymenial surface, hyphal system dimitic bearing simple-septa, thin- to thick-walled, yellowish brown asterosetae with acute tips, and thin-walled, echinulate, amyloid, globose basidiospores. Phanerochaete tongbiguanensis is characterized by the resupinate basidiomata with a white to cream hymenial surface, a monomitic hyphal system with simple-septa generative hyphae, the presence of subclavate cystidia covered with a lot of crystals, and oblong ellipsoid basidiospores (6–9 × 3–4.5 µm). Phlebiopsis fissurata is characterized by the membranaceous, tuberculate basidiomata with a buff to slightly brown hymenial surface, a monomitic hyphal system with simple-septa, conical cystidia, and broadly ellipsoid. Vararia yingjiangensis is characterized by a corky basidiomata with a pinkish buff to cinnamon-buff hymenial surface, cracking, yellowish dichohyphae with slightly curved tips, subulate gloeocystidia, and thick-walled, ellipsoid basidiospores (6.5–11.5 × 5–7 µm). The phylogenetic analyses of ITS + nLSU revealed that the two new species were nested into the genera Phanerochaete and Phlebiopsis within the family Phanerochaetaceae (Polyporales), in which Phanerochaete tongbiguanensis was sister to P. daliensis; Phlebiopsis fissurata was grouped with P. lamprocystidiata. Two new species were clustered into the genera Asterostroma and Vararia within the family Peniophoraceae (Russulales), in which Asterostroma yunnanense was sister to A. cervicolor; Vararia yingjiangensis formed a single branch.
Patient-Generated Health Data (PGHD): Understanding, Requirements, Challenges, and Existing Techniques for Data Security and Privacy
Authors: Khatiwada Pankaj , Yang Bian , Lin Jia-Chun , Blobel Bernd
Published: March 2024

The evolution of Patient-Generated Health Data (PGHD) represents a major shift in healthcare, fueled by technological progress. The advent of PGHD, with technologies such as wearable devices and home monitoring systems, extends data collection beyond clinical environments, enabling continuous monitoring and patient engagement in their health management. Despite the growing prevalence of PGHD, there is a lack of clear understanding among stakeholders about its meaning, along with concerns about data security, privacy, and accuracy. This article aims to thoroughly review and clarify PGHD by examining its origins, types, technological foundations, and the challenges it faces, especially in terms of privacy and security regulations. The review emphasizes the role of PGHD in transforming healthcare through patient-centric approaches, their understanding, and personalized care, while also exploring emerging technologies and addressing data privacy and security issues, offering a comprehensive perspective on the current state and future directions of PGHD. The methodology employed for this review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Rayyan, AI-Powered Tool for Systematic Literature Reviews. This approach ensures a systematic and comprehensive coverage of the available literature on PGHD, focusing on the various aspects outlined in the objective. The review encompassed 36 peer-reviewed articles from various esteemed publishers and databases, reflecting a diverse range of methodologies, including interviews, regular articles, review articles, and empirical studies to address three RQs exploratory, impact assessment, and solution-oriented questions related to PGHD. Additionally, to address the future-oriented fourth RQ for PGHD not covered in the above review, we have incorporated existing domain knowledge articles. This inclusion aims to provide answers encompassing both basic and advanced security measures for PGHD, thereby enhancing the depth and scope of our analysis.
A Review of Research on Progress in the Theory and Practice of Eco-Product Value Realization
Authors: Liu Jiemin , Su Xuejiao , Liu Yuanmeng , Shui Wei
Published: March 2024

The value realization of ecological products is currently a rapidly evolving research topic; however, the definition of its concept, type, and operation mechanism remains relatively ambiguous. Operating in accordance with the PRISMA guidelines, this review employs keyword retrieval and screening, utilizing VOSviewer and word cloud mapping for analysis, in order to reveal three primary research domains related to ecological product value realization. Based on thorough screening and the analysis of high-quality literature, this study comprehensively accomplished the following objectives: (1) clarifying the fundamental concepts of ecosystem services and ecological products, their interrelationships, and the scope of research on ecological products; (2) clarifying the basic connotation of realizing the value of ecological products; (3) demonstrating government-led approaches, market-driven approaches and collaborative pathways for realizing the value of ecological products; (4) reviewing international cases related to realizing the value of public ecological products, quasi-public ecological products, and operational ecological products. The academic contributions of this study are (1) expanding the theoretical framework for realizing the value of ecological products; (2) providing a Chinese perspective on global research on pathways to realize value from ecological products; and (3) offering a novel approach to revitalizing regional economies and improving local ecological environments. Based on this research, several shortcomings and future directions in this field are identified: (1) insufficient clarity, standardization, and uniformity in evaluation and measurement methods; (2) the absence of comparison between ecological products and urban economic products; (3) inadequate exploration of multi-stakeholder allocation and coordination mechanisms; (4) limited research on the role of capital markets in allocating ecological product resources.
The Moderating Effect of Social Participation on the Relationship between Urban Green Space and the Mental Health of Older Adults: A Case Study in China
Authors: Zheng Yuan , Cheng Bin , Dong Letian , Zheng Tianxiang , Wu Rong
Published: March 2024

China is experiencing unprecedented urbanization and aging. Previous studies mostly ignored the internal mechanism of the effect of urban green space on the mental health of older adults. Consequently, the relationship between social participation in urban green spaces and mental health remains uncertain. Therefore, this study explored the impact of urban green spaces, social participation, and other factors on the mental health of older adults and investigated the mechanisms of these effects. This study used linear regression models and conducted a moderating effect analysis using data from the 2018 China Labor Dynamics Survey, comprising 3501 older adults in 146 cities in China. Furthermore, we analyzed differences between solitary and non-solitary older adults. The results indicated that urban green space, road density, physical health, history of hospitalization, subjective well-being, and economic satisfaction significantly affected mental health. Social participation played a significant positive moderating role in the connection between green spaces and mental health among older adults. For solitary older adults, social participation weakened the positive impact of green spaces on mental health; for non-solitary older adults, social participation enhanced the positive impact of green spaces on mental health. These findings could contribute to the future construction of aging-friendly cities in China and help optimize urban construction and strategies for building healthy environments.
Transformation of Abandoned Railways into Tourist Itineraries/Routes: Model of Revitalization of Marginal Rural Areas
Authors: Ristić Dušan , Vukoičić Danijela , Ivanović Marko , Nikolić Milena , Milentijević Nikola , Mihajlović Ljiljana , Petrović Dragan
Published: March 2024

Railways that were once utilized by conventional speed trains but now lay technologically outdated and neglected are scarcely in use today, with many lying abandoned. These rail networks sprawl across vast areas, posing a substantial impediment to sustainable land use and management. Our research advocates for the adoption of tourist itinerary/route as a viable model for the transformation of abandoned railways into sustainable and functional systems. This innovative concept involves repurposing abandoned railways into tourist itineraries with the aim of utilizing them for tourism and commercial ventures. Recognizing a knowledge gap, particularly the absence of scientifically grounded models, on a selected case study (abandoned regional railway number 223 in the Toplica District, Serbia), we develop and present a model for the identification and Tourist Evaluation of Abandoned Railways (TEAR model). The defined model comprises a total of 27 sub-indicators categorized into four groups of indicators: natural tourist values (NV), anthropogenic tourist values (AV), tourist attractiveness of the railway (TA), and functional values (FV). The findings from the TEAR model suggest that the abandoned railway holds significant tourism value, with a rating of ≥0.7. Specifically, three sets of indicators—NV, AV, and TA—indicate a high level of tourist values (≥0.7), while FV falls within a moderate range of tourist values (0.4 ≤ V < 0.7). This endeavor not only supports sustainable local and regional development but also contributes to the enhancement of rural landscapes and the revitalization of rural areas. Importantly, this initiative aligns directly and indirectly with several Sustainable Development Goals (SDGs), thus fostering progress towards broader economic, societal, and environmental objectives.
Counteract Soil Consumption through Ecosystem Services and Landscape Restoration for an Efficient Urban Regeneration
Authors: Fazia Celestina , Nahiduzzaman Kh Md , Al-Ramadan Baqer , Aldosary Adel , Moraci Francesca
Published: March 2024

Soil consumption, marked by the expansion of artificial land cover for residential, productive, and infrastructural purposes, is a concerning trend in Italy, as revealed by the Copernicus land monitoring program. The issue is exacerbated by agricultural intensification and urbanization, particularly affecting regions like Lombardia and Piemonte. However, Sicilia, Abruzzo, and Lazio experience notable increases in processes of abandonment and re-naturalization. Data from Ispra highlights the need for in-depth study, especially in regions like Sicilia, where contrasting phenomena occur. This study utilizes Ispra data to monitor and formulate strategies for mitigating soil consumption and safeguarding ecosystem services. The research aligns with objectives related to combating climate change and facilitating the ecological transition of territories. The complexity of land consumption, influenced by interdependent factors, is evident in the achieved results. Effective strategies for containment and re-naturalization involve the implementation of town planning regulations and multi-level behavioral pathways. This study aims to identify contextual actions that can reduce land consumption, promote de-impermeabilization, and encourage re-naturalization, focusing on enhancing ecosystem services in land use activities. Thus, it focuses on understanding the contributions of ecosystem services, landscape restoration and green infrastructure on climate mitigation, and a reduction in land consumption in urban regeneration processes. As well, through open-source systems, it is important to monitor in real time the trend of the quantity of factors and variables and the state of the environment, and the reasons to intervene with systemic strategies and actions constitutes another lens of focus.
Modeling Landscape Influence on Stream Baseflows for Watershed Conservation
Authors: Randhir Timothy O. , Klosterman Kimberly B.
Published: March 2024

Instream flows are vital to the ecology of riverine and riparian systems. The influence of watershed characteristics on these systems is helpful in developing landscape policies to maintain these flows. Watershed characteristics like precipitation, forest cover, impervious cover, soil drainage, and slope affect baseflows. Spatial analysis using GIS and nonlinear regression analysis is used to analyze spatial and temporal information from gauged watersheds in Massachusetts to quantify the relationship between baseflows and watershed metrics. The marginal functions of landscape factors that reflect changes in baseflow are quantified. This information is then applied to watershed policy toward improving base flows. The interactions of three fixed attributes, soil drainage, rainfall incidence, and slope, are analyzed for the manageable landscape attributes of impervious and forest cover. Developing watershed policy to protect baseflows involves evaluating the complex interactions and functional relationships between these landscape factors and their use in watershed conservation planning.
Mediterranean Wildfires’ Effect on Soil Quality and Properties: A Case from Northern Euboea, Greece
Authors: Megremi Ifigeneia , Stathopoulou Eleni , Vorris Efstathios , Kostakis Marios , Karavoltsos Sotirios , Thomaidis Nikolaos , Vasilatos Charalampos
Published: March 2024

Physical and chemical soil properties are affected by wildfires. Post-wildfire runoff may contain nutrient loads and particulate matter that negatively impact soil, surface water, and groundwater. According to data from the Copernicus Emergency Management Service, devastating wildfires on Northern Euboea Island, Greece, in August 2021 destroyed more than 50,910 ha. Coniferous and broad-leaved forests mostly covered the affected area, according to CORINE. Topsoil and subsoil samples were collected from burned areas and analyzed for physicochemical parameters: pH, electrical conductivity, and organic carbon. After digestion with aqua regia, the Pb, Zn, Cd, Cu, Mn, Fe, Cr, Ni, Co, and As ‘pseudo total’ contents were determined. Leaching experiments were conducted to evaluate the levels of potentially toxic elements leaching from soils and the impact of environmental conditions. The leachates were analyzed for Pb, Zn, Cd, Cu, Mn, Fe, Cr, Ni, Co, As, Ca, Mg, Na, and K. Overall, most of the concentrations of the studied elements were higher in fire-affected soils than in unburned ones. Similar findings for element concentrations have been confirmed between topsoils and subsoils, with the latter exhibiting lower values. The increased ‘pseudo total’ values of Cr, Ni, Fe, Co, and Mn in all the soil samples, along with the medium to high positive correlations between them, indicate that geogenic factors play a major role in controlling element enrichment. High concentrations of Mn, Ni, and As in soil leachates exceeded the EU maximum permissible limits, indicating a potential ecological risk to natural water quality and, subsequently, to human health. The correlation coefficients between elements in fire-affected and unburned soils suggested that their geogenic origins were mainly associated with the ultramafic rocks and related ores of the study area. The elements’ concentrations in the leachates were significantly lower than their ‘pseudo total’ contents in soil, with no correlation between them. The reducing order of elements leachability did not coincide with the decreasing order of elements ‘pseudo total’ median values in soils. The decreasing order of element abundance in soil leachates coincides with their relative extractability and differs from the decreasing order of their ‘pseudo total’ median values in soils. Neutral to alkaline, soil pH conditions and organic carbon content, which substantially influence the retention and mobility of elements, presented different patterns among the studied elements, with only Mn, Cr, and Co showing correlations. The increased content of organic matter in fire-affected soils suggests that the combustion of vegetation was incomplete.
Long-Term Survivability of Tardigrade Paramacrobiotus experimentalis (Eutardigrada) at Increased Magnesium Perchlorate Levels: Implications for Astrobiological Research
Authors: Wilanowska Paulina , Rzymski Piotr , Kaczmarek Łukasz
Published: March 2024

Perchlorate salts, including magnesium perchlorate, are highly toxic compounds that occur on Mars at levels far surpassing those on Earth and pose a significant challenge to the survival of life on this planet. Tardigrades are commonly known for their extraordinary resistance to extreme environmental conditions and are considered model organisms for space and astrobiological research. However, their long-term tolerance to perchlorate salts has not been the subject of any previous studies. Therefore, the present study aimed to assess whether the tardigrade species Paramacrobiotus experimentalis can survive and grow in an environment contaminated with high levels of magnesium perchlorates (0.10–0.25%, 0.6–1.5 mM ClO4− ions). The survival rate of tardigrades decreased with an increase in the concentration of the perchlorate solutions and varied from 83.3% (0.10% concentration) to 20.8% (0.25% concentration) over the course of 56 days of exposure. Tardigrades exposed to 0.15–0.25% magnesium perchlorate revealed significantly decreased body length. Our study indicates that tardigrades can survive and grow in relatively high concentrations of magnesium perchlorates, largely exceeding perchlorate levels observed naturally on Earth, indicating their potential use in Martian experiments.
Assessing the Natural Source Zone Depletion of a Petroleum-Contaminated Clayey Soil Site in Southern China Combining Concentration Gradient Method and Metagenomics
Authors: Xu Zhe , Zhang Min , Ning Zhuo , He Ze , Zhang Fenge
Published: March 2024

Natural source zone depletion (NSZD) is the main process of LNAPL (Light Non-Aqueous Phase Liquid) removal under natural conditions. The NSZD rates assessed ranged from 0.55 to 11.55 kg·m−2·a−1 (kilograms per square meter per year) in previous studies. However, most of these data were obtained from sandy sites, with few clayey sites. To gain knowledge of NSZD in clayey soil sites, the study assessed the NSZD of a petroleum hydrocarbon-contaminated clayey soil site in China, combining the concentration gradient method with metagenomic sequencing technology. The results show that the abundance of methane-producing key enzyme mcrA gene in the source zone was more abundant than in background areas, which suggests that there was methanogenesis, the key process of NSZD. The concentration gradients of oxygen and carbon dioxide existed only in shallow soil (<0.7 m), which suggests that there was a thin methane oxidation zone in the shallow zone. The calculated NSZD rates range from 0.23 to 1.15 kg·m−2·a−1, which fall within the moderate range compared to previous NSZD sites. This study expands the knowledge of NSZD in clayey soil and enriches the attenuation rate data for contaminated sites, which is of significant importance in managing petroleum contaminants.
A Closed Queueing Networks Approach for an Optimal Heterogeneous Fleet Size of an Inter-Facility Bulk Material Transfer System
Authors: Amjath Mohamed , Kerbache Laoucine , Smith James MacGregor
Published: March 2024

Background: This study addresses optimising fleet size in a system with a heterogeneous truck fleet, aiming to minimise transportation costs in interfacility material transfer operations. Methods: The material transfer process is modelled using a closed queueing network (CQN) that considers heterogeneous nodes and customised service times tailored to the unique characteristics of various truck types and their transported materials. The optimisation problem is formulated as a mixed-integer nonlinear programming (MINLP), falling into the NP-Hard, making exact solution computation challenging. A numerical approximation method, a modified sequential quadratic programming (SQP) method coupled with a mean value analysis (MVA) algorithm, is employed to overcome this challenge. Validation is conducted using a discrete event simulation (DES) model. Results: The proposed analytical model tested within a steel manufacturing plant’s material transfer process. The results showed that the analytical model achieved comparable optimisation of the heterogeneous truck fleet size with significantly reduced response times compared to the simulation method. Furthermore, evaluating performance metrics, encompassing response time, utilisation rate, and cycle time, revealed minimal discrepancies between the analytical and the simulation results, approximately ±8%, ±8%, and ±7%, respectively. Conclusions: These findings affirm the presented analytical approach’s robustness in optimising interfacility material transfer operations with heterogeneous truck fleets, demonstrating real-world applications.
(10E,15Z)-12-(Dimethylsulfonio)-9,13-dihydroxyoctadeca-10,15-dienoate
Authors: Nishino Haruka , Zhang Bo-Tao , Uchida Hajime , Kamio Michiya , Nagai Hiroshi , Satake Masayuki
Published: March 2024

A novel oxylipin, okeanoate (1), was isolated from the Okinawan cyanobacterium Okeania hirsuta. The structure of 1 was elucidated based on spectroscopic data including 1D and 2D NMR, as well as high-resolution mass spectrometry. This is the first oxylipin with a dimethylsulfonium moiety in the middle of the hydrocarbon chain.
Suitability of Polymers for 3D-Printing Laboratory Models for Shaking Table Experiments: Discussion and Indications
Authors: Boroń Paweł , Budzik Grzegorz , Dulińska Joanna Maria , Przeszłowski Łukasz , Tatara Tadeusz
Published: March 2024

This paper presents a comprehensive assessment of the suitability of seven commercially available polymers for crafting laboratory models designed for dynamic shaking-table tests using 3D-printing technology. The objective was to determine whether 3D-printed polymer models are effective for dynamic assessments of structures. The polymers underwent experimental investigations to assess their material properties, i.e., the elastic modulus, the mass density, and the limit of linear-elastic behaviour. The following methodology was applied to obtain the correct values of elasticity moduli and yield points of the polymers: (1) the uniaxial tensile test, (2) the compression test, and (3) the three-point loading test. The filament density was determined as the ratio of sample mass to its volume. The results indicate substantial variations in stiffness, density, and elasticity limits among them. For the similarity analysis, an existing reinforced concrete chimney 120 m high was chosen as a prototype. A geometric similarity scale of 1:120 for a laboratory mock-up was adopted, and a numerical model of the mock-up was created. The similarity scales were calculated for mock-ups made of each filament. Based on these scales, numerical calculations of natural frequencies and dynamic performance under a strong earthquake were carried out for models made of different polymers. Assessment of the polymers’ suitability for laboratory models revealed positive outcomes. The agreement between field experiments, shaking-table tests, and numerical predictions in terms of natural frequencies was observed. Maximum stresses resulting from the earthquake indicated the satisfactory performance of the model below the linear-elastic limit. Despite differences in material properties, the selected polymers were deemed suitable for 3D-printing models for shaking-table tests. However, the discussion raised some important considerations. The upper frequency limit of the shaking-table imposes restrictions on the number of natural frequencies that can be determined. Numerical assessments of natural frequencies are recommended to prevent underestimation and to assess the feasibility of their determination. Additionally, resonance during natural frequency determination may lead to exceeding the linear-elastic limit, affecting filament properties, and making the similarity criteria invalid. Practically, this research contributes insights for planning shaking-table tests, aiding in selecting the most suitable filament and highlighting crucial considerations to ensure reliable and accurate dynamic assessments.
A Study on the Shrinkage and Compressive Strength of GGBFS and Metakaolin Based Geopolymer under Different NaOH Concentrations
Authors: Chen Yen-Chun , Lee Wei-Hao , Cheng Ta-Wui , Li Yeou-Fong
Published: March 2024

Geopolymers (GPs) are gaining prominence due to their low carbon emissions and sustainable attributes. However, one challenge with GPs, particularly those made with ground granulated blast furnace slag (GGBFS), is their significant shrinkage during the geopolymerization process, limiting its practical applicability. This study focuses on how the substitution ratio of metakaolin (MK) and the concentration of sodium hydroxide (NaOH) in the activator can influence the shrinkage and strength of a GGBFS-based GP. The experimental approach employed a 3 × 3 parameter matrix, which varied MK substitution ratios (0%, 50%, and 100%) and adjusted the NaOH concentration (6 M, 10 M, and 14 M). The results revealed that increasing MK substitution, particularly with 6 M NaOH activation, reduced the GP shrinkage but also diminished compressive strength, requiring higher NaOH concentrations for strength improvement. Statistical tools, including analysis of variance (ANOVA) and second-order response surface methodology (RSM), were employed for analysis. ANOVA results indicated the significant impacts of both the MK content and NaOH concentration on compressive strength, with no observable interaction. However, the shrinkage exhibited a clear interaction between MK content and NaOH concentration. The RSM model accurately predicted compressive strength and shrinkage, demonstrating a high predictive accuracy, for which the coefficients of determination (R2) were 0.99 and 0.98, respectively. The model provides a reliable method for determining the necessary compressive strength and shrinkage for GGBFS-based GP based on MK substitution and NaOH concentration. Within the optimization range, the RSM model compared with experimental results showed a 6.04% error in compressive strength and 0.77% error in shrinkage for one interpolated parameter set. This study establishes an optimized parameter range ensuring a GP performance that is comparable to or surpassing OPC, with a parameter set achieving a compressive strength of 34.9 MPa and shrinkage of 0.287% at 28 days.
Preparation of Antimony-Doped Tin Oxide Fly Ash Antistatic Composite and Its Properties in Filling EVA
Authors: Qiu Ying , Wang Caili , Zhao Chunxue , Yao Guoxin , Wang Zhixue , Yang Runquan
Published: March 2024

As a common coal-based solid waste, fly ash is widely used in material filling. However, due to the high resistivity of fly ash itself, the antistatic performance of the filling material is poor. Therefore, antistatic composite powder was prepared by coating nano-sized antimony-doped tin oxide (ATO) on the surface of fly ash, and its preparation mechanism was discussed. The composite powders were characterized by SEM, EDS, XRD and FTIR. The results show that the interaction between SiO2 and SnO2 appears at the wave number of 727.12 cm−1, and the obvious SnO2 crystal phase appears on the surface of fly ash. The volume resistivity of calcined fly ash is 1.72 × 1012 Ω·cm, and the volume resistivity of ATO fly ash is reduced to 6 × 103 Ω·cm. By analyzing the limiting oxygen index, melt index, tensile strength, elongation at break, cross-section morphology and surface electrical resistivity of EVA, it was found that the addition of antistatic powder to EVA can improve its antistatic performance without deteriorating the mechanical properties of EVA.
Data-Driven Multi-Objective Optimization Approach to Loaded Meshing Transmission Performances for Aerospace Spiral Bevel Gears
Authors: Zhou Zhenyu , Shao Wen , Tang Jinyuan
Published: March 2024

Loaded meshing transmission performance optimization has been an increasingly significant target for the design and manufacturing of aerospace spiral bevel gears with low noise and high strength. An innovative data-driven multi-objective optimization (MOO) method is proposed for the loaded meshing transmission performances of aerospace spiral bevel gears. Data-driven tooth surface modeling is first used to obtain a curvature analysis of loaded contact points. An innovative numerical loaded tooth contact analysis (NLTCA) is applied to develop the data-driven relationships of machine tool settings with respect to loaded meshing transmission performance evaluations. Moreover, the MOO function is solved by using an achievement function approach to accurate machine tool settings output, satisfying the prescribed requirements. Finally, numerical examples are given to verify the proposed methodology. The presented approach can serve as a powerful tool to optimize the loaded meshing transmission performances with higher computational accuracy and efficiency than the conventional methods.
Two-Step PM Procedure for Fabrication of Super-Engineering Plastic Gears
Authors: Aizawa Tatsuhiko , Miyata Tomohiro , Endoh Kiyoyuki
Published: March 2024

The two-step PM (powder metallurgy)-route procedure was proposed to fabricate a super-engineering plastic gear directly from powder feedstock. Its lightweight, fully dense integrity and high-stiffness has been found to be suitable for reducers in robotics and electric vehicles, as they work even in severe environmental conditions. In this study, the green compaction and sinter-forging processes were used to consolidate the polyimide powder feedstock and to sinter forge the solid preform into the final products. To demonstrate the high density of preforms and sinter-forged gears, a hardness measurement and X-ray computer tomography were employed. The gear-grade balancing was also evaluated to describe the effect of fine sinter-forging conditions on the dimensional quality of polyimide gears. High gear grade with JIS-2 class proved that the polyimide was useful as a matrix of lightweight and high-strength gears.
Optimization of Truck–Cargo Online Matching for the Less-Than-Truck-Load Logistics Hub under Real-Time Demand
Authors: Tang Weilin , Chen Xinghan , Lang Maoxiang , Li Shiqi , Liu Yuying , Li Wenyu
Published: March 2024

Reasonable matching of capacity resources and transported cargoes is the key to realizing intelligent scheduling of less-than-truck-load (LTL) logistics. In practice, there are many types and numbers of participating objects involved in LTL logistics, such as customers, orders, trucks, unitized implements, etc. This results in a complex and large number of matching schemes where truck assignments interact with customer order service sequencing. For the truck–cargo online matching problem under real-time demand, it is necessary to comprehensively consider the online matching process of multi-node orders and the scheduling of multi-types of trucks. Combined with the actual operation scenario, a mixed-integer nonlinear programming model is introduced, and an online matching algorithm with a double-layer nested time window is designed to solve it. By solving the model in a small numerical case using Gurobi and the online matching algorithm, the validity of the model and the effectiveness of the algorithm are verified. The results indicate that the online matching algorithm can obtain optimization results with a lower gap while outperforming in terms of computation time. Relying on the realistic large-scale case for empirical analysis, the optimization results in a significant reduction in the number of trips for smaller types of trucks, and the average truck loading efficiency has reached close to 95%. The experimental results demonstrate the general applicability and effectiveness of the algorithm. Thus, it helps to realize the on-demand allocation of capacity resources and the timely response of transportation scheduling of LTL logistics hubs.
Eigenvalue Problem Describing Magnetorotational Instability in Outer Regions of Galaxies
Authors: Mikhailov Evgeny , Khasaeva Tatiana
Published: March 2024

The existence of magnetic fields in spiral galaxies is beyond doubt and is confirmed by both observational data and theoretical models. Their generation occurs due to the dynamo mechanism action associated with the properties of turbulence. Most studies consider magnetic fields at moderate distances to the center of the disk, since the dynamo number is small in the marginal regions, and the field growth should be suppressed. At the same time, the computational results demonstrate the possibility of magnetic field penetration into the marginal regions of galaxies. In addition to the action of the dynamo, magnetorotational instability (MRI) can serve as one of the mechanisms of the field occurrence. This research is devoted to the investigation of MRI impact on galactic magnetic field generation and solving the occurring eigenvalue problems. The problems are formulated assuming that the perturbations may possibly increase. In the present work, we consider the eigenvalue problem, picturing the main field characteristics in the case of MRI occurrence, where the eigenvalues are firmly connected with the average vertical scale of the galaxy, to find out whether MRI takes place in the outer regions of the galaxy. The eigenvalue problem cannot be solved exactly; thus, it is solved using the methods of the perturbation theory for self-adjoint operators, where the eigenvalues are found using the series with elements including parameters characterizing the properties of the interstellar medium. We obtain linear and, as this is not enough, quadratic approximations and compare them with the numerical results. It is shown that they give a proper precision. We have compared the approximation results with those from numerical calculations and they were relatively close for the biggest eigenvalue.
The Role of Data on the Regularity of Solutions to Some Evolution Equations
Authors: Porzio Maria Michaela
Published: March 2024

In this paper, we study the influence of the initial data and the forcing terms on the regularity of solutions to a class of evolution equations including linear and semilinear parabolic equations as the model cases, together with the nonlinear p-Laplacian equation. We focus our study on the regularity (in terms of belonging to appropriate Lebesgue spaces) of the gradient of the solutions. We prove that there are cases where the regularity of the solutions as soon as t>0 is not influenced at all by the initial data. We also derive estimates for the gradient of these solutions that are independent of the initial data and reveal, once again, that for this class of evolution problems, the real “actors of the regularity” are the forcing terms.
Gaussian Mixture Estimation from Lower-Dimensional Data with Application to PET Imaging
Authors: Tafro Azra , Seršić Damir
Published: March 2024

In positron emission tomography (PET), the original points of emission are unknown, and the scanners record pairs of photons emitting from those origins and creating lines of response (LORs) in random directions. This presents a latent variable problem, since at least one dimension of relevant information is lost. This can be solved by a statistical approach to image reconstruction—modeling the image as a Gaussian mixture model (GMM). This allows us to obtain a high-quality continuous model that is not computationally demanding and does not require postprocessing. In this paper, we propose a novel method of GMM estimation in the PET setting, directly from lines of response. This approach utilizes some well-known and convenient properties of the Gaussian distribution and the fact that the random slopes of the lines are independent from the points of origin. The expectation–maximization (EM) algorithm that is most commonly used to estimate GMMs in the traditional setting here is adapted to lower-dimensional data. The proposed estimation method is unbiased, and simulations and experiments show that accurate reconstruction on synthetic data is possible from relatively small samples.
John von Neumann’s Space-Frequency Orthogonal Transforms
Authors: Stefanoiu Dan , Culita Janetta
Published: March 2024

Among the invertible orthogonal transforms employed to perform the analysis and synthesis of 2D signals (especially images), the ones defined by means of John von Neumann’s cardinal sinus are extremely interesting. Their definitions rely on transforms similar to those employed to process time-varying 1D signals. This article deals with the extension of John von Neumann’s transforms from 1D to 2D. The approach follows the manner in which the 2D Discrete Fourier Transform was obtained and has the great advantage of preserving the orthogonality property as well as the invertibility. As an important consequence, the numerical procedures to compute the direct and inverse John von Neumann’s 2D transforms can be designed to be efficient thanks to 1D corresponding algorithms. After describing the two numerical procedures, this article focuses on the analysis of their performance after running them on some real-life images. One black and white and one colored image were selected to prove the transforms’ effectiveness. The results show that the 2D John von Neumann’s Transforms are good competitors for other orthogonal transforms in terms of compression intrinsic capacity and image recovery.
Preparation and Gas Separation of Amorphous Silicon Oxycarbide Membrane Supported on Silicon Nitride Membrane
Authors: Jin Hengguo , Xu Xin
Published: March 2024

An amorphous silicon oxycarbide membrane supported on a silicon nitride membrane substrate was prepared. A starting suspension containing polyhydromethylsiloxane (PHMS), tetramethyltetravinyl-cyclotetrasiloxane (TMTVS) and a platinum catalyst was first prepared and spin-coated on a silicon nitride membrane, and then the suspension was cross-linked and cured, followed by pyrolyzing at 1000 °C under a flowing Ar atmosphere. A dense amorphous silicon oxycarbon ceramic membrane with a thickness of about 1.8 µm was strongly bonded to the Si3N4 membrane substrate. The single gas permeation of H2 and CO2 indicated that the ideal permeation selectivity of H2/CO2 was up to 20 at 25 °C and 0.5 MPa with good long-term stability, indicating the potential application of the obtained membrane for hydrogen purification.
Application of the Theory of Critical Distance (TCD) to the Breakage of Cardboard Cutting Blades in Al7075 Alloy
Authors: Morettini Giulia , Landi Luca , Burattini Luca , Stornelli Giulia , Foffi Gianluca , Di Schino Andrea , Cianetti Filippo , Braccesi Claudio
Published: March 2024

The study presented in this paper was undertaken in response to two instances of unexpected blade breakage in the cutting blade used in a Carton Wrap machine (CW). Failure of the Al7075 alloy blade occurred at an indentation during typical operational loading conditions. Subsequent metallographic examinations of the fractured samples confirmed that both cases were attributed to fatigue failure. The main objective of this study is to investigate potential causes of fatigue failure in the CW blade using simplified linear elastic static numerical simulations through Finite Element Analysis (FEA). In this research, we employed the well-established Theory of Critical Distance (TCD), and this case study provided a contextualization at an industrial level. Furthermore, the analysis focused on a second key aspect: proposing a new blade geometry aimed at mitigating the identified issues and eliminating possible causes of failure. In this context, the actual stress concentration at the indentation was determined using the TCD with Line Method (LM). The results from the numerical simulations indicated that the new blade geometry significantly reduced stress concentration, resulting in a risk factor reduction of approximately four compared to the original blade design, even under non-optimal operating conditions. Overall, in conjunction with simple linear static FEA, the proposed numerical approach provided substantial support for designers, especially in fault analysis and when comparing different industrial solutions.
Modified Split Mandrel Method and Equipment to Improve the Fatigue Performance of Structural Components with Fastener Holes
Authors: Maximov Jordan , Duncheva Galya , Anchev Angel , Dunchev Vladimir , Daskalova Petya
Published: March 2024

Fastener holes are among the most common natural stress concentrators in metal structures. The life cycles of various structural elements, such as those in aircraft structures, automobiles, and rail-end bolt joints, are limited by fatigue damage around the holes. An effective approach to delay the formation and growth of fatigue macrocracks is to introduce residual hoop compressive stresses around the holes. Two methods have become established in the prestressing of fastener holes in aircraft components, split sleeve and split mandrel, which implement one-sided processes. The common disadvantage of both methods is the complex procedure due to the need for high accuracy of the initial holes. This article presents a new modified split mandrel method providing the same tightness (interference fit) with a wide tolerance of the pre-drilled hole diameters, reducing the number of technological cycle steps and production costs. To implement the new method, a functionally connected tool and a device with a hydraulic drive were developed. An extensive experimental study of 2024-T3 AA specimens was carried out to evaluate the effectiveness of the method under a high scattering of the pre-drilled holes. The new method provided a deep zone of residual hoop compressive stresses on both faces of the specimens after cold working and after hole final reaming. The removal of a plastically deformed layer around the hole of suitable thickness during the final reaming decreased the axial gradient of residual hoop stress distribution. Fatigue tests on a tensile pulsating cycle verified the effectiveness of the modified split mandrel method to significantly increase the fatigue life by 6.6 times based on 106 cycle fatigue strength compared to the conventional case of machining the holes. The obtained S-N curves for three groups of samples with initial hole diameters of 8.0, 8.1, and 8.2 mm, which were cold worked with the same tightness of 0.32 mm and final reamed, aligned well, indicating that the new method can provide constant fatigue strength for a given stress amplitude.